MX2007012274A

MX2007012274A - Mixed polymer superabsorbent fibers containing cellulose .

Info

Publication number: MX2007012274A
Application number: MX2007012274A
Authority: MX
Inventors: S Amanda Weerawarna; Su Bing
Original assignee: Weyerhaeuser Co
Priority date: 2006-10-02
Filing date: 2007-10-02
Publication date: 2008-10-28
Also published as: EP1911467A1; KR20080030943A; CA2603476A1

Abstract

A mixed polymer composite fiber including a carboxyalkyl cellulose, a galactomannan polymer or a glucomannan polymer, and cellulose fiber. A method for making mixed polymer composite fibers containing cellulose fibers in which cellulose fibers are dispersed in an aqueous solution comprising a carboxyalkyl cellulose and a galactomannan polymer or a glucomannan polymer in water to provide an aqueous fiber dispersion; the aqueous dispersion treated with a first crosslinking agent to provide a gel; the gel mixed with a water-miscible solvent to provide composite fibers; and the composite fibers treated with a second crosslinking agent to provide crosslinked fibers.

Description

SUPER ABSORBENT FIBERS OF MIXED POLYMER CONTAINING CELLULOSE BACKGROUND OF THE INVENTION Absorbent personal care products, such as infant diapers, adult incontinence guards, and feminine care products, typically contain an absorbent core that includes super absorbent polymer particles distributed within a fibrous matrix. The superabsorbent absorbent materials can be dilated in water, generally insoluble in water, which have a high absorbency capacity of body fluids. The super absorbent polymers (SAPs) in common use are mostly derived from acrylic acid, which are in themselves derived from petroleum oil, a non-renewable raw material. Acrylic acid polymers and SAPs are generally recognized as non-biodegradable. Despite its wide use, some segments of the absorbent product market are concerned about the use of materials derived from non-renewable petroleum oil and their non-biodegradable nature. Acrylic acid based on polymers also comprises a significant portion of the cost structure of diapers and incontinence guards. SAP users are interested in lower cost SAPs. The high costs derive in part from the cost structure of the manufacture of acrylic acid which, in turn, depends on the fluctuating price of the petroleum oil. Also, when diapers are discarded after use, they usually contain considerably less than their theoretical or maximum body fluid content. In other words, in terms of their ability to hold fluids, they are "over designed." This "over design" constitutes an inefficiency in the use of SAPs. The inefficiency results in part from the fact that the SAPs are designed to have a high gel strength (as demonstrated by their high absorbency under load or AUL). The high resistance gel (from the dilation) of SAP particles currently used, helps them retain many of the particles between the empty space, which is useful for quickly capturing the fluid. However, this "empty volume" high, simultaneously results in a lot of interstitial liquid (between particles) in the product in the saturated state. When there is a lot of interstitial fluid the value "wet again" or the "wet feeling" of an absorbent product are compromised. In absorbent personal care products, soft pine pulp from the southern United States is commonly used in conjunction with SAP. This soft pulp is recognized worldwide as the preferred fiber for absorbent products. The preference is based on the advantageous high fiber length of the soft pulps (approximately 2.8 mm) and their relative ease of processing from a pulp sheet of moisture zone to a mesh laid to the air. The soft pulp is also made from biodegradable or renewable cellulose pulp fibers.

Compared to SAPs, these fibers are economical on a per-mass basis, although they tend to be more expensive on a per-unit liquid maintenance basis. These soft pulp fibers, for the most part, absorb into the interstices in the middle of the fibers. For this reason, a fibrous matrix easily releases the fluid acquired during the application of pressure. The tendency to release the purchased liquid can result in significant moisture in the skin during the use of an absorbent product that includes a core formed exclusively of cellulose fibers. Such products also tend to filter the acquired liquid because the liquid that is not effectively retained in said absorbent fibrous core. The super absorbent produced in the form of fiber has a distinct advantage over the particles formed in some applications. Said super absorbent fiber can be elaborated in a cloth form without adding the fiber that is not super absorbent. Said cloths may also be less bulky due to the elimination or reduction of the fiber used that is not super absorbent. The liquid acquisition will be more uniform compared to a fiber cloth with super absorbent particle change. Thus, there is a need for a super absorbent fibrous material that is produced simultaneously, made from a biodegradable renewable resource similar to cellulose that is economical. In this way, the super absorbent material can be used in the designs of absorbent products that are efficient. These and other objects are achieved by the present invention set forth above.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides a mixed polymer composite fiber that includes a carboxyalkylcellulose, a galactomannan polymer or a glucomannan polymer and cellulose fiber. The mixed polymeric composite fibers include a plurality of non-permanent metallic crosslinks between fibers. The present invention also provides a method for making mixed polymeric composite fibers containing cellulose. The method includes the steps of dispersing the cellulose fibers in an aqueous solution comprising a carboxyalkylcellulose and a galactomannan polymer or a glucomannan polymer in water to provide an aqueous fiber dispersion; treating the aqueous dispersion with a first crosslinking agent to provide a gel; mix the gel with a solvent that is mixed with water to provide the composite fibers; and treating the composite fibers with a second crosslinking agent to provide the crosslinked fibers.

BRIEF DESCRIPTION OF THE DRAWINGS The above aspects and many of the advantages that accompany the present invention will be more readily appreciated as they are better understood with reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: Figure 1 is a photograph of the representative mixed polymeric composite fibers of the present invention. Figure 2 is a photograph of the representative mixed polymeric composite fibers of the present invention; and Figure 3 is a digital scanning electron microscope (1000x) photograph representative of the mixed polymeric composite fibers of the present invention (cross section).

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a mixed polymer composite fiber. The present invention provides methods for making the mixed polymer composite fiber. The mixed polymer composite fiber is a fiber comprising a carboxyalkylcellulose, a galactomannan polymer or a glucomannan polymer and cellulose. The carboxyalkylcellulose, which is mainly in the sodium salt form, can be in other forms of salts such as potassium and ammonia forms. The mixed polymer composite fiber is formed by intermolecular crosslinking of the mixed polymer molecules, and is insoluble in water and can be dilated in water. In one aspect, the present invention provides a mixed polymer composite fiber that additionally includes cellulose. As used in the present description, the term "mixed polymeric composite fiber" refers to a fiber that is the compound of at least three different polymers (ie, mixed polymer). The mixed polymer composite fiber is a homogeneous composition that includes two associated water-soluble polymers: (1) a carboxyalkylcellulose and (2) and either a galactomannan polymer or a glucomannan polymer. The carboxyalkylcellulose useful in the preparation of the mixed polymer composite fiber has a degree of substitution of carboxyl group (DS) from about 0.3 to about 2.5. In one embodiment, the carboxyalkylcellulose has a degree of carboxyl group substitution of from about 0.5 to about 1.5. Although a variety of carboxyalkylcelluloses are suitable for use in the manufacture of the mixed polymer composite fiber, in one embodiment, the carboxyalkylcellulose is carboxymethylcellulose. In another embodiment, the carboxyalkylcellulose is carboxyethylcellulose.

The carboxyalkylcellulose is present in the polymeric composite fiber blended in an amount from about 60 to about 99% by weight roasted in the weight of the mixed polymer composite fiber. In one embodiment, the carboxyalkylcellulose is present in an amount from about 80 to about 95% by weight based on the weight of the mixed polymer composite fiber. In addition to carboxyalkylcellulose derived from wood pulp containing a part of carboxyalkylhemicellulose, the carboxyalkylcellulose derived from the non-wood pulp, such as cotton pellets, is suitable for preparing the mixed polymer composite fiber. For the carboxyalkyl cellulose derived from wood products, the mixed polymer fibers include carboxyalkyl hemicellulose in an amount of up to about 20% by weight based on the weight of the mixed polymer composite fiber. The galactomannan polymer useful for the manufacture of the blended polymeric composite fiber of the present invention can include any of a variety of galactomannan polymers. In one embodiment, the galactomannan polymer is guar gum. In another embodiment, the galactomannan polymer is a locust bean gum. In a further embodiment, the galactomannan polymer is tara gum. The glucomannan polymer useful in the manufacture of the blended polymeric composite fiber of the present invention can include any of a variety of glucomannan polymers. In one embodiment, the glucomannan polymer is a Konjac gum. In another embodiment, the galactomannan polymer is locust bean gum. In a further embodiment, the galactomannan polymer is a tara gum. The galactomannan polymer or glucomannan polymer is present in an amount from about 1 to about 20% by weight based on the weight of the mixed polymer composite fiber. In one embodiment, the galactomannan polymer or glucomannan polymer is present in an amount of from about 1 to about 15% by weight based on the weight of the mixed polymer composite fiber. Cellulose is present in an amount from about 2 to about 15% by weight based on the weight of the mixed polymer composite fiber. In one embodiment, the cellulose is present in an amount from about 5 to about 10% by weight based on the weight of the mixed polymer composite fiber. Although available from other sources, suitable cellulose fibers are derived primarily from wood pulp. The wood pulp fibers suitable for use with the present invention can be obtained from well-known chemical processes such as sulfite and Kraft processes, with or without subsequent bleaching. The pulp fibers can also be processed by thermomechanical, chemithermomechanical, or combinations thereof.

A pulp of high alpha cellulose, is also a fiber of suitable wood pulp. The preferred wood pulp fiber is produced by chemical methods. The fibers of ground, recycled or secondary wood pulp fibers and pulp fibers of bleached and unbleached wood can be used. Soft woods and hard woods can be used. Suitable fibers are commercially available from a number of companies, including Weyerhaeuser Company. For example, suitable cellulose fibers produced from southern pine, which can be used with the present invention are available from Weyerhaeuser Company under the designations CF416, NF405, PL416, FR516 and NB416. Other suitable fibers include eucalyptus fibers and soft northern wood. The preparation of the mixed polymer composite fiber is a multi-step process. First, the water-soluble carboxyalkylcellulose and the galactomannan polymer or glucomannan polymer are dissolved in water to provide a polymer solution. The cellulose fiber is then added and dispersed in the polymer solution. Then, the first crosslinking agent is added and mixed to obtain a mixed polymeric composite gel formed by the intermolecular crosslinking of the water soluble polymers intimately associated with the dispersed cellulose fiber. The first suitable crosslinking agents include crosslinking agents that are reactive towards hydroxyl groups and carboxyl groups. Representative crosslinking agents include metal crosslinking agents, such as aluminum (III) compounds, titanium (IV) compounds, bismuth (III) compounds, boron (III) compounds, and zirconium (IV) compounds. The numbers in parentheses in the preceding list of metal crosslinking agents refer to the valence of the metal. The mixed polymer composite fiber is generated by rapid mixing of the polymeric composite gel mixed with a solvent that can be mixed in water. This fiber generated after the first crosslinking has a high level of viscosity when it is hydrated and forms soft gels. Therefore, these fibers can not be used in absorbent applications without additional treatment. The mixed polymer composite fiber thus obtained is further crosslinked (eg, crosslinked surface) by treatment with a second crosslinking agent in a solvent-containing water that can be mixed in water. The solvent composition that can be mixed in water and water, are such that the fiber does not change its fiber shape and returns to the gel state. The second crosslinking agent can be the same as or different from the first crosslinking agent. The blended polymer fibers of the present invention are substantially insoluble in water, while having the ability to absorb water. The fibers of the present invention are presented insoluble in water by virtue of a plurality of metallic cross-links between non-permanent fibers. As used in the present description, the term "non-permanent fiber metal crosslinks" refers to the natural crosslinking occurring within the individual modified fibers of the present invention (ie, between fibers) and between and between of the polymer molecules that make up the fiber. The fibers of the present invention are crosslinked between fibers with metal crosslinks. Metal crosslinks arise as a consequence of an associative interaction (e.g., linkage) between the functional groups in the fiber polymers (e.g., carboxy, carboxylate or hydroxyl groups) and a multivalent metal species. Suitable multivalent metal species include metal ions having a valence of three or greater and having the ability to form associative interactions between the polymer and the functional groups of the polymer (e.g., the reaction towards associative interaction with the carboxy, carboxylate or hydroxyl groups). The polymers are crosslinked when the multivalent metal species form the associative interactions between the polymer and the functional groups in the polymers. A crosslinking may be formed intermolecularly within a polymer or may be formed intermolecularly between two or more polymer molecules within a fiber. The extent of the intermolecular crosslinking affects the water solubility of the composite fibers (ie, greater crosslinking, greater insolubility) and the ability of the fiber to dilate on contact with an aqueous liquid.

The fibers of the present invention include metallic crosslinks between non-permanent fibers, both intermolecularly and intramolecularly in the population of the polymeric molecules. As used herein the term "non-permanent crosslinking" refers to metal crosslinking formed with two or more functional groups of a polymeric molecule (intramolecularly) or formed with two or more functional groups of two or more polymeric molecules ( intermolecularly). It will be appreciated that the process of dissociation and new association (breaking and reforming crosslinks) of multivalent metal ions and polymer molecules is dynamic and also occurs during liquid acquisition. During the acquisition of water, the individual fibers and bundles of fibers that expand and change to gel state. The ability of non-permanent metallic crosslinks to dissociate and associate under the acquisition of water imparts greater freedom to the gels to expand if the gels were cross-linked in a restrictive manner by permanent cross-links that do not have the capacity to disassociate and associate again. Covalent organic crosslinks, such as ether crosslinks, are permanent crosslinks that do not have the ability to dissociate and associate again. The fibers of the present invention have fiber widths from about 2 pm to 50 pm (or greater) and a roughness ranging from smooth to rough.

The representative blended polymer composite fibers of the present invention are illustrated in Figures 1 to 3. Figure 1 is a photograph of the representative blended polymer composite fibers of the present invention. Figure 2 is a photograph of the representative mixed polymeric composite fibers of the present invention. Figure 3 is a digital scanning electron microscope photograph (1000x) of the representative mixed polymeric composite fibers of the present invention (cross sectional view) (Sample 4, of Table 1). The fibers of the present invention are highly absorbent fibers. The fibers have a free expansion capacity from about 30 to about 60 g / g (0.9% saline), a centrifugation retention capacity (CRC) from about 15 to about 35 g / g (0.9% saline) and an absorbency under load (AUL) from about 15 to about 30 g / g (0.9% saline). The fibers of the present invention can be formed into protectors by conventional methods including air-laying techniques to provide fibrous cloths having a variety of liquid absorbency characteristics. For example, the cloths that absorb liquid at an index from approximately 10 mL / second to approximately 0.005 mL / second (application of 10 mL of 0.9% saline solution) The integrity of the cloths can vary from mild to very strong.

The mixed polymeric composite fibers of the present invention are insoluble in water and can be dilated in water. Insolubility in water is imparted to the fiber by intermolecular crosslinking of the mixed polymer molecules and the capacity of expansion in water is imparted to the fiber by the presence of carboxylate anions with the associated cations. The fibers are characterized by having a relatively high liquid absorbency capacity for water (for example, pure water or aqueous solutions, such as saline solutions or biological solutions such as urine). Additionally, because the mixed polymer fiber has the structure of a fiber, the mixed polymer composite fiber also has the ability to actively absorb liquids. The blended polymeric composite fiber of the present invention advantageously has double properties of high liquid absorbency and active liquid absorbency. The mixed polymer fibers that have the capacity to actively absorb fluids, they are useful in medical applications, such as wound dressings and others. Mixed polymer fibers having the ability to rapidly absorb active urine are useful in the applications of personal care absorbent products. The mixed polymer fibers can be prepared having a range of active properties from slow to fast for water and 0.9% aqueous saline solutions.

The blended polymeric composite fibers of the present invention are useful as superabsorbent in personal care absorbent products (e.g., infant diapers, sanitary napkins, and adult incontinence products). Due to their ability to actively absorb liquids and absorb liquids, the blended polymeric composite fibers of the present invention are useful in a variety of applications, including, for example, wound dressings, cable insulation, bags and absorbent sheets, and packaging materials. In one aspect of the present invention, methods for making the mixed polymeric composite fibers are provided. In one embodiment, the method for making the mixed polymeric composite fibers includes the steps of: (a) dissolving the carboxyalkylcellulose (e.g., mostly in salt form, with or without carboxyalkyl hemicellulose) and a galactomannan polymer or a polymer of glucomannan in water to provide an aqueous polymer solution: (b) dispersing the cellulose fibers in the polymer solution to provide an aqueous fiber dispersion; (c) treating the aqueous dispersion with a first crosslinking agent to provide a gel; (d) mixing the gel with a solvent that can be mixed in water to provide the composite fibers; and (e) treating the composite fibers with a second crosslinking agent to provide mixed polymeric composite fibers. The mixed polymeric composite fibers prepared in this manner can be formed into fibers and dried.

In the process, a carboxyalkylcellulose, a galactomannan polymer or a glucomannan polymer, and the cellulose fibers are combined in water to provide an aqueous dispersion of cellulose in an aqueous polymer solution. Suitable carboxyalkylcelluloses have a degree of substitution of the carboxyl group from about 0.3 to about 2.5 and in one embodiment have a degree of substitution of the carboxyl group from about 0.5 to about 1.5. In one embodiment, the carboxyalkylcellulose is carboxymethylcellulose. The aqueous dispersion from about 60 to about 99% by weight of carboxyalkylcellulose based on the weight of the mixed polymer composite fiber. In one embodiment, the aqueous dispersion includes from about 80 to about 95% by weight of carboxyalkylcellulose based on the weight of the mixed polymer composite fiber. The carboxyalkylhemylcellulose can also be present from about 0 to about 20 weight percent based on the weight of the mixed polymeric composite fibers. The aqueous dispersion also includes a galactomannan polymer or a glucomannan polymer. Suitable galactomannan polymers include guar gum, locust bean gum and tara gum. Suitable glucomannan polymers include a Konjac gum. The galactomannan polymer or glucomannan polymer can be from natural sources or can be obtained from genetically modified plants. The aqueous dispersion includes from about 1 to about 20% by weight of galactomannan polymer or glucomannan polymer based on the weight of the mixed polymer composite fiber, and in one embodiment, the aqueous dispersion includes from about 1 to about 15% by weight of galactomannan polymer or glucomannan polymer based on the weight of the mixed polymeric composite fibers. The aqueous dispersion also includes the cellulose fibers, which are added to the aqueous polymer solution. The aqueous dispersion includes from about 2 to about 15% by weight of the cellulosic fibers based on the weight of the mixed polymer composite fiber and, in one embodiment, the aqueous dispersion includes from about 5 to about 10% by weight of cellulose fibers based on the weight of the mixed polymeric composite fibers. In the method, the aqueous dispersion includes the carboxyalkylcellulose, the galactomannan polymer or glucomannan polymer and the cellulosic fibers, are treated with a first crosslinking agent to provide a gel. The first suitable crosslinking agents include crosslinking agents that are reactive towards hydroxyl groups and carboxyl groups. Representative crosslinking agents include metal crosslinking agents, such as aluminum (III) compounds, titanium (IV) compounds, bismuth (III) compounds, boron (III) compounds, and zirconium (IV) compounds. The numbers in the parentheses in the preceding list of metallic crosslinking agents refer to the valence of the metal. Representative metal crosslinking agents include aluminum sulfate; aluminum hydroxide; aluminum dihydroxyacetate (stabilized with boric acid); other aluminum salts of carboxylic acids and inorganic acids; other aluminum complexes, such as Ultrion 8186 from Nalco Company (aluminum chloride hydroxide); boric acid; sodium metaborate; ammonium zirconium carbonate; zirconium compounds containing inorganic ions or organic ions or natural ligands; ammonium citrate of bismuth and other bismuth salts of carboxylic acids and inorganic acids; titanium (IV) compounds, such as titanium bis (triethylamine), bis (isopropoxide) (IV) (commercially available from The Dupont Company under the designation Tyzor TE); and other titanates with alkoxide or carboxylate ligands. The first crosslinking agent is effective to associate and crosslink the carboxyalkylcellulose (with or without carboxyalkylemicellulose) and the galactomannan polymer molecules intimately associated with the cellulose fibers. The first crosslinking agent is applied in an amount from about 0.1 to about 20% by weight based on the total weight of the mixed polymer composite fiber. The amount of the first crosslinking agent applied to the polymers will vary depending on the crosslinking agent. In general, the fibers have an aluminum content of from about 0.04 to about 0.8% by weight based on the weight of the polymeric composite fiber mixed by the crosslinked fibers of aluminum, a titanium content of from about 0.10 to about 1. .5% by weight based on the weight of the composite fiber of the mixed polymer by the aluminum crosslinked fibers, a zirconium content of from about 0.09 to about 2.0% by weight based on the weight of the mixed polymer composite fiber for the zirconium crosslinked fibers, and a bismuth content of from about 0.09 to about 5.0% by weight based on the weight of the mixed polymer composite fiber for the crosslinked fibers of bismuth. The gel formed by treating the aqueous dispersion of the cellulose fibers in the aqueous solution of carboxyalkylcellulose and the galactomannan polymer with a first crosslinking agent is then mixed with a solvent that can be mixed in water to provide the composite fibers. Suitable solvents that can be mixed in water include alcohols and ketones that can be mixed in water. Representative solvents that can be mixed in water include acetone, methanol, ethanol, isopropanol and mixtures thereof. In one embodiment, the solvent that can be mixed in water is ethanol. In another embodiment, the solvent that can be mixed in water is isopropanol.The volume of the solvent that can be mixed in water added to the gel varies from about 1: 1 to about 1: 5 (the volume used for processing the aqueous dispersion of carboxyalkylcellulose, gaiactomannan polymer and cellulose fibers) in the solvent that It can be mixed in water. In the method, mixing the gel with the solvent from which it can be mixed in water includes stirring to provide the composite fibers. The mixing step and the use of the solvent that can be mixed in water control the rate of dehydration and the exchange of solvent under the conditions of mixing to cut and provides the formation of composite fiber. The mixture can be made using a variety of devices including high agitators, Hobart mixers, British disintegrators and mixers. For these mixing devices, the mixer provides more cutting and the high agitator provides the smaller cut. As noted above, the cut formation results from the mixing of the gel cut with the solvent that can be mixed in water and the effects of solvent exchange and generation of composite fiber in the resulting mixed solvent. In one embodiment, mixing the gel with the solvent that can be mixed in water to provide the composite fibers comprises mixing 1 or 2% solids in the water with a tall mixer or stirrer. In another embodiment, mixing the gel with a solvent that can be mixed in water to provide the composite fibers comprises, mixing 4% solids in water with a mixer. For large-scale production, mixing equipment with suitable mixing capabilities is used. The composite fibers formed from the mixing step are treated with a second crosslinking agent to provide the mixed polymeric composite fibers (crosslinked fibers). The second crosslinking agent is effective in the further crosslinking of the composite fibers (e.g., surface crosslinking). Suitable second crosslinking agents include crosslinking agents that are reactive toward hydroxyl groups and carboxyl groups. The second crosslinking agent can be the same as or different from the first crosslinking agent. The second representative crosslinking agents include the metal crosslinking agents noted above useful as the first crosslinking agents. The second crosslinking agent is applied at a relatively higher level than the first crosslinking agent per unit mass of the fiber. This provides a higher degree of crosslinking on the surface of the fiber relative to the interior of the fiber. As described above, the metal crosslinking agents form crosslinks between the carboxylate anions and the metal atoms or hydroxyoxygen cellulose and the metal atoms. These crosslinks can migrate from one oxygen atom to another when the mixed polymer fiber absorbs water and forms a gel. However, they have a higher level of crosslinking on the surface of the fiber relative to the interior that provides a super absorbent fiber with an adequate balance in free expansion, the centrifugal retention capacity and the absorbency under load for the solutions watery and decreases the blocking of the gel that inhibits the transport of the liquid. The second crosslinking agent is applied in an amount from about 0.1 to about 20% by weight based on the total weight of the mixed polymeric composite fibers. The amount of the second crosslinking agent applied to the polymers will vary depending on the crosslinking agent. The fiber products have an aluminum content of from about 0.04 to about 2.0% by weight based on the weight of the mixed polymer composite fiber for the cross-linked aluminum fibers, a titanium content of from about 0.1 to about 4.5%. by weight based on the weight of the mixed polymer composite fiber for the titanium crosslinked fibers, a zirconium content of from about 0.09 to about 6.0% by weight based on the weight of the mixed polymer composite fiber for the zirconium crosslinked fibers and a bismuth content of from about 0.09 to about 5.0% by weight based on the Weight of mixed polymer composite fiber for crosslinked bismuth fibers. A second crosslinking agent can be the same or different from the first crosslinking agent. The mixture of two or more crosslinking agents in different proportions can be used in each crosslinking step. The preparation of the blended polymeric composite fibers of the present invention is described in Examples 1 to 4. The absorbency properties of the representative blended polymer composite fibers are summarized in Table 1. In Table 1, the term "% by weight of total weight, applied" refers to the amount of the first crosslinking agent applied to the total weight of CMC and guar gum.; "second crosslinking agent / 2g" refers to the amount of the second crosslinking agent applied per 2g of the first crosslinked product, "CMC 9H4F" refers to a carboxymethylcellulose commercially available from Hoechst Celanese under the designation; "KL-SW" refers to a CMC made from soft northern wood pulp; the "LV-PN" refers to a CMC made from pine pulp from the west coast; "NB416" refers to the fibers of the southern pine pulp; and "soft PA" refers to the soft wood pulp fibers of the north; "i-PrOH" refers to isopropanol; "EtOH" refers to ethanol; "wash w" refers to washing the treated fibers with 100% ethanol or 100% isopropanol before drying; and "washing wo" refers to the process in which the treated fibers are not washed before drying.

TEST METHODS The capacities of free expansion and retention of centrifugation The materials, procedure and calculations to determine the capacity of free expansion (g / g) and the capacity of retention of centrifugation (CRC) (g / g) were as follows.

Test materials: Japanese pre-made empty tea bags (available from Drugstore.com, TO GET 93 mm x 70 mm polyester tea bags with fold protector) (http: www.mesh.ne.jp/tokiwa/). Balance (precision of 4 decimal places, 0.0001 g for super absorbent polymer air-dried (ADS SPA) and weights of tea bags); chronometer; 1% saline; drip stand with pins (NLM 21.1); and laboratory centrifuge (NLM 21 1, gyro extractor-X turn, model 776S, 3,300 RPM, 120 v).

Test procedure: 1. Determine ADS solids content 2. Pre-weigh the tea bags to the nearest 0.001 g and record. 3. Weigh accurately 0.2025g +/- 0.0025g of test material (SAP), record and place in the bag of preweighed heavy tea (AD) bag weight). (ADS weight + AD bag weight + total dry weight). 4. Fold the edge of the tea bag over the closed bag. 5. Fill a container (at least 7.62 centimeters deep) with at least 5.08 centimeters with 1% saline solution. 6. Hold the tea bag (with the test sample) flat and shake to distribute the test material evenly through the bag. 7. Leave the tea bag on the surface of the saline solution and start the timer. 8. Wet the bags during the specified time (for example, 30 minutes). 9. Remove the tea bags carefully, being careful not to spill the contents of the bags, hold a pin on the drip stand for 3 minutes. 10. Carefully remove each bag, weigh and record (drip weight). 1 1. Place the tea bags on the walls of the centrifuge, being careful not to let them touch and carefully distribute them evenly around the wall. 12. Close the lid and start the stopwatch. Spin for 75 seconds. 13. Uncover and remove the bags. Weigh each bag and record the weight (spin weight).

Calculations: The material of the tea bag has an absorbance determined as follows: Free expansion capacity, factor = 5.78 Centrifugal capacity, factor = 0.50 Z = dry oven SAP weight (g) / air-dry SAP weight ( g) Free capacity (g / g): [(drip weight (g) - dry bag weight (g)) - (weight AD SAP (g))] - (dry bag weight) * 5.78) (weight AD SAP (g) * Z) Centrifugal holding capacity (g / g): [(spin weight (g) - dry bag weight (g)) - (weight AD SAP (g))] (dry bag weight) * 0.50) (weight AD SAP (g) * Z) Absorbency under load (AUL) The materials, procedure, and calculations to determine the AUL were as follows: Test materials: Mettler Toledo PB 3002 balance and BALANCE-LINK software or other compatible scales and software. Software configuration: record the weight of the balance every 30 seconds (this will be a negative number, the software can place each value in an Excel spreadsheet). Configuration of Kontes ULTRA-WARE 90 mm filter with a heat-prepared glass filter (coarse). Subject to stay; a 2 L glass bottle with an outlet tube near the bottom of the bottle; a plastic cap with gas tube through the cap that fits the bottle (air inlet); TYGON pipe, stainless steel rod assembly / Plexiglas plunger (71 mm diameter); weight of stainless steel with through hole drilling to place on the plunger (plunger and weight = 867g); VWR filter paper of 9.0 cm (Qualitative 413 catalog number 28310-048) cut to a size of 80 mm; SCOTCH double grip tape; and 0.9% saline solution.

Test procedure: 1. Level filter configuration with small level. 2. Adjust the height of the filter or filter level in the bottle, in such a way that the glass filter prepared by heat and saline level in the bottle are of the same height. 3. Make sure there are no wrinkles in the pipe or air bubbles in the pipe or under the glass filter plate prepared by heat. 4. Place the filter paper on the filter and place the stainless steel weight on the filter paper. 5. Wait 5 to 10 minutes while the filter paper gets completely wet and reaches the balance with the applied weight. 6. Zero balance 7. While waiting for the filter paper to reach equilibrium, prepare the plunger with double adhesive tape the bottom part. 8. Place the plunger (with the tape) on double graduation and zero graduation. 9. Place the plunger in the dry test material in such a way that a monolayer of material is adhered to the bottom by the double adhesive tape. 10. Weigh the plunger and the test material on the zero graduation and record the weight of the dry test material (dry material weight 0.15 g +/- 0.05 g). eleven . The filter paper must be in equilibrium for now at zero graduation. 12. Start the graduation registration software. 13. Remove the weight and place the plunger and the test material in the filter assembly. 14. Place the weight on the plunger assembly. 15. Wait for the test to complete (30 or 60 minutes) 16. Stop the graduation registration software.

Calculations: A = graduation reading (g) * -1 (weight of saline solution absorbed by the test material) B = Dry weight of test material (This can be corrected for moisture by multiplying the AD weight by% solid). AUL (g / g) = A / B (g of 1% saline solution / 1g of test material) The following examples are provided for the purpose of illustrating, not limiting the present invention.

EXAMPLES EXAMPLE 1 Preparation of representative mixed polymeric composite fibers: crosslinking of aluminum sulfate / aluminum sulfate In this example, the preparation is described as representative mixed polymeric crosslinked fibers with aluminum sulfate and aluminum sulfate is described. A solution of CMC 9H4F (20.0 g OD) in 900 ml of deionized water (DI) was prepared with vigorous stirring to obtain a solution. The guar gum (1.2 g) was dissolved in 50 ml of DI water and well mixed with the CMC solution. The soft pulp (1.0 g NB416) was added and the solution was stirred for one hour to allow complete mixing of the two polymers and the cellulose fiber. The polymer mixture was combined in the mixer for 5 minutes. 1.2 g octadecahydrate of aluminum sulfate was weighed and dissolved in 50 ml of DI water. Transfer the aluminum sulfate solution to the polymer solution and combine for 5 minutes to mix it well. The gel is left at room temperature (25 ° C) for one hour. Transfer the gel to a Waring type mixer with one liter of isopropanol. Mix for one minute at low speed (which produced a softer gel). Transfer the gel to a 19-liter plastic bucket.

Two liters of isopropanol are added and mixed rapidly with the vertical spiral mixer for 30 minutes. Filter and place the fiber in 500 ml of isopropanol and leave it for 5 minutes. The fiber is filtered and dried in an oven at a temperature of 66 ° C for 15 to 30 minutes. 0.32 g of aluminum sulphate octadecahydrate are dissolved in 100 ml of deionized water and mixed with 300 ml of denatured ethanol. To the stirred solution is added 2.0 g of fiber, prepared as described above, and left for 30 minutes at a temperature of 25 ° C. Filter the fiber and press it to remove the excess solution. The fiber product is filtered and dried at a temperature of 66 ° C for 15 minutes in a softened oven. Free dilation (60.6 g / g), centrifugation retention capacity (30.98 g / g), for 0.9% saline.

EXAMPLE 2 The Preparation of Representative Mixed Polymer Compound Fibers: Crosslinking of Aluminum Sulfate / Allominium Phosphate In this example, the preparation of representative mixed polymeric composite fibers crosslinked with aluminum sulfate and aluminum sulfate is described. A solution of CMC 9H4F (40.0 g OD) and 2.4 g of guar gum in 900 ml of deionized water was prepared in a Hobard mixer to obtain a viscous polymer solution in two hours. It mixes initially at speed one and increases the speed to two and finally to three. The soft pulp (4.0 g PA) in 50 ml of water was added and mixed at speed three for one hour. 1.2 g octadecahydrate of aluminum sulfate was dissolved in 50 ml of DI water. Transfer the crosslinked solution to the polymer solution and mix well in the Hobard mixer (initially at speed one and then gradually increase the speed to three as the crosslinked solution was absorbed into the gel (one hour) The gel is transferred to a Waring type mixer with one liter of isopropanol, mixed for two minutes at low speed (which produced a softer gel), two liters of isopropanol are added and combined at low speed and placed Stator power of 70 for one minute.Filter and place the fiber in one liter of isopropanol and in the mixer and combine it at low power and place the power of 70 for one minute.Filter the fiber and dry it in One oven at a temperature of 66 ° C for 15 to 30 minutes, 0.20 g of aluminum sulphate octadecahydrate were dissolved in 100 ml of deionized water and mixed with 300 ml of isopropanol, 2.0 g are added to the stirred solution. of fiber, prepared as described above, and left for 15 minutes at a temperature of 25 ° C. Filter the fiber and press it to remove the excess solution. Filter and dry the fiber at a temperature of 66 ° C for 15 minutes in an oven with softener. Free dilation (52.04 g / g), centrifugal holding capacity (21 .83 g / g), AUL at 0.3 psi (23.73 g / g) for 0.9% saline.

EXAMPLE 3 Preparation of representative mixed polymeric composite fibers: crosslinking of aluminum sulfate / aluminum sulfate In this example, the preparation of the representative mixed polymeric composite fibers crosslinked with aluminum sulfate and aluminum sulfate is described. A mild wood solution Kamloops (DS = 0.94) CMC (20.0 g OD) in 900 ml of deionized water was prepared with vigorous stirring to obtain a solution. The guar gum (1.2 g) was dissolved in 50 ml of DI water and well mixed with the CMC solution. The soft pulp (2.0 g NB416) was added and the mixture was stirred for one hour to allow complete mixing of the two polymers and the cellulose fiber. The mixture was combined in the mixer for 5 minutes. 0.8 g of aluminum sulphate octadecahydrate was weighed and dissolved in 50 ml of DI water. Transfer the aluminum sulphate solution to the polymer solution and combine for 5 minutes to mix well. The gel is left at room temperature (25 ° C) for one hour. The gel is transferred into a Waring type mixer with one liter of denatured ethanol. Mix for two minutes at low speed (which produced a mild gel), then add two liters of ethanol and combine at low power and place the stator power of 70 for one minute. Filter and place the fiber in 500 ml of ethanol and stir for 15 minutes. The fiber is filtered and dried in an oven at a temperature of 66 ° C for 15 minutes. 0.28 g of aluminum sulphate octadecahydrate is dissolved in 50 ml of deionized water and mixed with 150 ml of denatured ethanol. To the stirred solution is added 2.0 g of fiber, prepared as described above, and left for 30 minutes at a temperature of 25 ° C. The fiber is filtered and pressed to remove excess solution. Filter and dry the fiber at a temperature of 66 ° C for 15 minutes in an oven with softener. Free dilation (57.61 g / g), centrifugal holding capacity (25.45 g / g). AUL at 0.3 psi (22.26 g / g) for 0.9% saline.

EXAMPLE 4 The Preparation of Representative Mixed Poiimmer Compound Fibers: Crosslinking Aluminum Sulphate / Air Sufate i ni In this example, the preparation of cross-linked representative poiimeric composite fibers with aluminum sulfate and aluminum sulfate is described. A solution of Longview pine (DS = 0.98) CMC (40.0 g OD) and 2.4 g of guar gum in 900 ml of deionized water was prepared with the gradual increase in mixing speed in a Hobart mixer. The soft pulp (4.0 NB416) in 50 ml of DI water was added and mixed to allow to complete the mixture of the two polymers and the cellulose fiber. 1.2 g of aluminum sulphate octadecahydrate was dissolved in 50 ml of DI water. Transfer the aluminum sulfate solution to the polymer mixture and mix well. Leave the gel at room temperature (25 ° C) for one hour. The gel is transferred to a Waring type mixer with one liter of isopropanol. Mix for two minutes at low speed and place the stator power at 90 (which produced a softer gel), and then add 2 liters of isopropanol and combine at low power and place the stator power of 60 during a minute. Filter and place the fiber in one liter of isopropanol and stir for 15 minutes. Filter the fiber and dry it in an oven at a temperature of 66 ° C for 15 minutes. A small fraction with a size below 300 microns is filtered. 0.22 g of aluminum sulphate octadecahydrate is dissolved in 50 ml of deionized water and mixed with 150 ml of isopropanol. To the stirred solution is added 2.0 g of fiber, prepared as described above and left for 40 minutes at a temperature of 25 ° C. Filter the fiber and press it to remove the excess solution. The fiber is filtered and air dried at a temperature of 25 ° C. Free dilation (56.77 g / g), centrifugal holding capacity (28.95 g / g), AUL at 0.3 psi (22.66 g / g) for 0.9% saline.

TABLE 1. Composition and absorbency properties of super absorbent fiber precipitated from aqueous cross-linked mixtures of CMC, galactomannan and cellulose Sample CMC Gum Guar Cellulose First agent Second agent Solvent Dilation CRC AUL percentage of weight (percentage of crosslinking of free crosslinking (g / g) (g / g) (g / g) of total weight) weight of weight (percentage of / 2g the total fiber) weight of applied weight) 1 CMC 9H4F 5.2 NB416, 4.38% AI2 (S04) 3 2.63% 0.16g AI2 (S04) 3 i-PrOH 60.6 30.98 washing wo 2 CMC 9H4F 5.2 NB416, 4.38% AI2 (S04) 3 2.63% 0.16g AI2 (S04) 3 i-PrOH 46.87 9.68 washing wo 3 CMC 9H4F 5.0 NB416, 8.43% AI2 (S04) 3 1.68% 0.13g AI2 (S04) 3 i-PrOH 39.99 14.42 B (OH ) 3 0.4% wash wo 4 CMC 9H4F 5.0 NB416, 8.47% AI2 (S04) 3 1.69% 0.17g AI2 (SO ") 3 i-PrOH 45.62 13.31 wash wo 5 CMC 9H4F 5.1 PA Soft, 8.5% AI2 (S04) 3 1.27% 0.1 Og AI2 (S04) 3 i-PrOH 52.04 21.83 23.73 washing wo 6 CMC 9H4F 5.1 PA Soft, 8.5% AI2 (S04) 3 1.27% 0.12g AI2 (S04) 3 i-PrOH 38.37 8..08 washing wo 7 KL-SW 5.0 NB416, 8.47% AI2 (S04) 3 0.14g AI2 (S04) 3 i-PrOH 57.61 25.26 22.26 1..69% wash w 8 KL-SW 5.0 NB416, 8.47% AI2 (S04) 3 1.69% 0.16g AI2 (S0 4) 3 EtOH 48.87 19.47 19 wash w 9 KL-SW 5.0 NB416, 8.47% AI2 (S04) 3 1.69% 0.18g AI2 (S04) 3 EtOH 49.14 13.76 wash w 10 KL-SW 5.0 NB416, 8.47% AI2 (S04) 3 1.69% 0.16g AI2 (S04) 3 EtOH 44.4 9.04 wash w 11 KL-SW 5.0 NB416, 8.47% AI2 (SO ") 3 1.69% 0.15g AI2 (S04) 3 EtOH 55.96 20.73 25.26 wash w 12 LV-PN 5.1 PA Soft, 8.5% AI2 (S04) 3 1.27% 0.14g AI2 (S04) 3 -PrOH 49.82 19.41 wash w 13 LV-PN 5.1 PA Soft, 8.5% AI2 (S04) 3 1.27% 0.12g AI2 (S04) 3 i-PrOH 54.48 23.2 wash w 14 LV-PN 5.1 PA Soft, 8.5% AI2 (S04). 1.27% 0.1 Og AI2 (S04) 3 i-PrOH 55.51 27.43 wash w 15 LV-PN 5.1 PA Soft, 8.5% AI2 (S04) 3 1.27% 0.08g AI2 (S04) 3 i-PrOH 57.62 31.2 ilavado w 16 LV- PN 5.1 PA Soft, 8.5% AI2 (S04) 3 1.27% 0.11g AI2 (SO4) 3 i-PrOH wash w Although the illustrative modalities have been illustrated and described, it will be appreciated that various changes may be made therein, without departing from the spirit and scope of the present invention.

Claims

NOVELTY OF THE INVENTION CLAIMS

1 .- A mixed polymeric composite fiber, comprising a carboxyalkylcellulose, a galactomannan polymer or glucomannan polymer and cellulose fiber and further comprising crosslinking of multivalent metal ions between fibers, comprising one or more metal ions selected from the group consisting of aluminum compounds, titanium compounds, bismuth compounds, boron compounds and zirconium compounds.

2. The fiber according to claim 1, further characterized in that the carboxyalkylcellulose is present in an amount from about 60 to about 99 weight percent based on the total weight of the fiber.

3. The fiber according to claim 1, further characterized in that the galactomannan polymer or glucomannan polymer is present in an amount from about 1 to about 20 weight percent based on the total weight of the fiber.

4. The fiber according to claim 1, further characterized in that the cellulose fiber is present in an amount from about 2 to about 15 weight percent based on the total weight of the fiber.

5. - A method for making the fibers of any of the preceding claims, characterized in that it comprises; (a) dispersing the cellulose fibers in an aqueous solution comprising a carboxyalkylcellulose and a galactomannan polymer or a glucomannan polymer in water to provide an aqueous fiber dispersion; (b) treating the dispersion of aqueous water with a first crosslinking agent to provide a gel; (c) mixing the gel with a solvent that can be mixed in water to provide the composite fibers; and (d) treating the composite fibers with a second crosslinking agent to provide the crosslinked fibers, wherein the crosslinking agents are selected from the group consisting of aluminum compounds, titanium compounds, bismuth compounds, boron compounds and compounds of zirconium.

6. - The method according to claim 5, further characterized in that the aqueous dispersion comprises from about 60 to about 99 weight percent carboxyalkylcellulose based on the total weight of the crosslinked fibers.

7. - The method according to claim 5, further characterized in that the aqueous dispersion comprises from about 1 to about 20 weight percent of galactomannan polymer or glucomannan polymer based on the total weight of the crosslinked fibers.

8. - The method according to claim 5, further characterized in that the aqueous dispersion comprises from about 2 to about 15 weight percent of cellulose fibers based on the total weight of the crosslinked fibers.

9. - The method according to any of claims 5 to 8, further characterized in that mixing the gel with the solvent that can be mixed in water comprises agitating them to provide the fibers.

10. - The method according to any of claims 5 to 9, further characterized in that each of the crosslinking agents is present in an amount from about 0.1 to about 20 weight percent based on the total weight of the cross-linked fibers.