Patent Description:
Superabsorbent polymers (SAPs) can absorb and retain extremely large amounts of a liquid relative to their own mass. Such water-absorbing polymers, that are classified as hydrogels when cross-linked, absorb aqueous solutions through hydrogen bonding with water molecules. A SAP's ability to absorb water depends on the ionic concentration of the aqueous solution. SAP materials used in manufacturing diapers are characterized of having a free absorbency to distillate water higher than <NUM>/g.

A particular class of SAP used in manufacture of diapers is represented by those materials characterized by a high rate of free absorbency and a value of absorbency under load (AUL) higher than <NUM>/g in salt solutions of <NUM> % NaCl at a pressure of <NUM>. Absorbency Under Load (AUL) characterization of SAP type materials are discussed in Bucholtz et al.

Biodegradable SAP materials belong to the following classes: a) materials consisting only of crosslinked biopolymers; b) materials consisting only of crosslinked synthetic polymers and c) composite materials consisting of synthetic polymers and biopolymers in certain variations: in inter crosslinking type connection without chemical agents; in crosslinking type connection with chemical agents; graft type; intercomplexate type and interpenetrate type. [ Hoffman (<NUM>)].

Copolymers such as for example styrene maleic acid are known in the art as SAP materials and various methods of copolymerization are known as well.

Von Bonin in <CIT> shows that maleic anhydride, which melts at <NUM>° C, may be used as polymerization medium itself at temperatures above its melting point, in particular for copolymerization with methacrylic acid and derivatives thereof, without any uncontrollable reactions taking place which would result in unreproducible and unusable products. In the course of polymerization, maleic acid anhydride is built into the polymers and at the same time polymerization is controlled so that the polymers obtained are stirrable at temperatures below <NUM>° C. This effect is enhanced in particular by the addition of so-called regulators. The following quantities are used, based on the total quantity of monomers put into the process, including also the maleic acid anhydride which initially serves as reaction medium: <NUM> to <NUM>% by weight, preferably <NUM> to <NUM>% by weight, of maleic acid anhydride and <NUM> to <NUM>% by weight, preferably <NUM> to <NUM>% by weight, of comonomers, at least <NUM>% by weight, preferably <NUM>% by weight of this quantity of comonomers.

In the method employed for polymerization, the molten maleic acid anhydride initially constitutes the polymerization medium. As polymerization progresses and most of the maleic acid anhydride initially present has been used up by copolymerization, the function of polymerization medium may be taken over by the polymer melt. Unreacted maleic acid anhydride may either be left in the product or removed by extraction or distillation. The same principle of synthesis is found in <CIT>; <CIT>; <CIT> or <CIT>.

A disadvantage of the copolymerization of maleic anhydride with other monomers when the maleic anhydride it is also a reaction medium refers to the fact that the chemical process occurs at temperature higher than <NUM> and at high pressure conditions which in general generates polymers with low molecular mass.

The bulk copolymerization of maleic anhydride with different vinyl monomers inclusive styrene is accompanied by intense exothermic phenomena. Referring to this aspect, Sahibi Belkhiria et al (<NUM>) show that the intensity of exothermic phenomenon can be diminished if the molar fraction of the styrene in the mass of reaction is smaller than <NUM>, when also the styrene conversion to polymer is advanced (in the same conditions it can be obtained a conversion of styrene to polymer higher than <NUM>%). The same principles are mentioned in: Z. Florjanczyk et al. (<NUM>); D. Comissiong et al. (<NUM>), <CIT> ; <CIT>.

Bucevschi et al in <CIT> shows the preparation of styrene maleic acid copolymer based on the method which uses an excess of maleic anhydride as reaction medium with a ratio of styrene: maleic anhydride between <NUM>:<NUM> and <NUM>:<NUM> by weight, in which the styrene maleic anhydride polymer is soluble and then the polymer of maleic anhydride type is converted in acid type by its hydrolysis with water. Disadvantages of the synthesis procedure consists in : a) the exothermic process is controlled only through the intensity of heat transfer obtained by cooling the mass of reactants; b) a high consumption of water used to purify the polymer; c) efficiency of conversion of raw materials into the styrene maleic acid polymer is low.

Exothermic phenomena which occurs in the polymerization and copolymerization process is known in art. The control of this phenomenon is achieved by using inhibitors and retardants. Middle, et al (<NUM>); Roman Geier et al (<NUM>); Nedal Y et al (<NUM>); S. Rowe (<NUM>) and <CIT>; <CIT>; <CIT>; <CIT> or Z. Florjanczyk et al. (<NUM>)"; Zbigniew Florjanczyk et al.

Preparation of SAP materials made of styrene maleic acid copolymers in the form of hydrogels and using carboxylate synthetic material is known in art. The chemical principles for their preparation refers in most cases to crosslinking of these polymers with different chemical agents from the category mentioned in <CIT>, and as an example for the use of absorbent polymeric materials can be seen the following: <CIT>; <CIT> ; <CIT>; <CIT>; <CIT>; <CIT>; <CIT> ;<CIT> ; <CIT> <CIT>, <CIT>; <CIT>, <CIT>; <CIT>, <CIT>; <CIT> ; <CIT>; <CIT> ; <CIT>, <CIT> ; <CIT>, <CIT> ; <CIT> ; <CIT> or <CIT> and Hossein Hosseinzadeh (<NUM>) ; Z. Florjanczyk et al. (<NUM>) ; Zbigniew Florjanczyk et al. In the same class of materials are included and those resulted from carboxylate polymers, cross-linked with different polymers from which result composite polymeric materials as in: <CIT>; <CIT>; <CIT> or C. Demitri et al. (<NUM>) ; S. Rowe (<NUM>) ; Deniz Aydemir et al.

<CIT> presents the preparation of a polymeric composite made from styrene maleic acid copolymer as salt with monovalent cations and gelatin which after drying is thermally cross-linked in two steps. After the second step of thermal crosslinking, an increase of water absorbency and swelling velocity is obtained in aqueous media.

The degree of crosslinking affects the absorbent capacity and gel strength of a SAP material. Absorbent capacity is a measure of the amount of fluid which a given amount of superabsorbent polymer will absorb. Gel strength indicates the tendency of the hydrogel once formed to deform under an applied stress. Polymers exhibiting inadequate gel strength will form a hydrogel which deforms and fills the void space in an absorbent article, inhibiting absorbent capacity and fluid distribution throughout the article. Polymers having low absorbent capacity are incapable of absorbing a sufficient amount of the fluid encountered in use of a diaper or other absorbent article. A polymer having a high gel strength generally possesses a low absorption capacity, and a polymer having a high absorption capacity typically possesses a low absorption rate because of gel blocking phenomenon or low gel strength after absorption. Another characteristic that a superabsorbent polymer must possess is an acceptable level of extractable polymer remaining within the SAP. The extractable polymer can leach out of a hydrogel when fluids contact the superabsorbent. The extractables that leach out of the superabsorbent apparently lower the absorption speed and capacity of the superabsorbent, resulting in leakage of the fluid from an absorbent article.

Most of the methods found in art discuss the surface cross-linking of polymeric materials which have three dimensional structure generated before the surface treatment and these can be seen in: <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>, <CIT>; <CIT>; <CIT>; <CIT>; <CIT> and respectively Enas M. Ahmed et al. (<NUM>) ; Mohammad J. Zohuriaan-Mehr et al (<NUM>) ; Steffen Jockusch et al.

A technical issue related to SAP material production which require AUL is referred to the products' granulometry and requires a particle size of polymer particles higher than <NUM> microns in the final product. The term "particle size" in the context of SAP materials that have particles of different geometrical forms, refers to an average diameter.

Biodegradable SAP materials are known, as can be seen in Raphael M. Ottenbrite et al. (<NUM>) ; Enas M. Ahmed et al. (<NUM>) ; Abraham J. Domb et al. (<NUM>) ; Rajiv Dabhi1 et al. (<NUM>) ; Fidelia N. Nnadi (<NUM>); Alessandro Sannino et al (<NUM>) ; Francesco F. Montesano et al. (<NUM>); Fidelia Nnadi et al(<NUM>) and <CIT>; <CIT>; <CIT>; <CIT> ; <CIT>. Regarding the biodegradability of material that include substance as styrene see: Rakesh Singh et al (<NUM>); P. Galgali et al (<NUM>); Niall D. O'Leary et al (<NUM>).

SAP materials obtained from styrene -maleic anhydride copolymers and biopolymers such as gelatin are known in art as: <CIT>; <CIT>; <CIT> at which the biodegradation is evaluated versus the enzyme from the gastrointestinal tract.

The invention discloses a new and improved method for production of superabsorbent polymers (SAP) used in the manufacture of diapers that are biodegradable and have a high absorbency under load (AUL).

The invention also discloses a method for the production of a composite polymeric material based on synthetic polymer and natural polymer, the composite having a 3D macromolecular configuration. The composite material may be either crosslinked or non-crosslinked. When non-crosslinked, the polymeric composite material (usually in granular form) may be treated with coating agents and subsequently exposed to thermal treatment (in one step or two or more steps) that lead to conversion of non-crosslinked polymeric composite to a crosslinked polymeric composite with a three dimensional macromolecular configuration and high absorbency under load.

In a preferred embodiment, the polymeric composite material is biodegradable. In another preferred embodiment the method generates as end product a single solid phase with granulometric size characteristic for using in diapers. Granulometric size refers to the average diameter of grains in SAP.

Alternatively, two solid phases are obtained: a small solid phase (SSP), with particles size not higher than <NUM> microns, that can be recycled; and a large solid phase (LSP) with particle size higher than <NUM> microns, preferably between <NUM> and <NUM> microns.

In a preferred embodiment the SAP material is made of styrene maleic anhydride copolymer (SMA) by bulk copolymerization using an excess of maleic anhydride to styrene, whereas maleic anhydride functions as a solvent for the resulted polymer.

In a further aspect the invention provides a biodegradable polymeric composite represented by the formula:
[SMAC(-)D(+)B]S]}W, wherein:.

In a preferred embodiment B is gelatin and D is selected from Li(+), Na(+), K(+),and NH<NUM> (+).

In another preferred embodiment the amount of B relative to SMAC in the composite is at least <NUM>-<NUM> % (dry basis), preferably at least <NUM>-<NUM> % (dry basis) and more preferably the amount of B relative to SMAC in the composite is at least <NUM>-<NUM> % (dry basis).

In another aspect the invention provides a method of preparing a biodegradable polymeric composite having an absorbency under load (AUL) that is higher than <NUM>/g in aqueous solution of <NUM>% NaCl, comprising:.

In another aspect the invention provides a biodegradable polymeric composite represented by the formula:
{[VMAC(-)D(+)B]S]}W, wherein:.

The invention will now be described with reference to the drawings, wherein.

This invention presents a method for production of a biodegradable superabsorbent composite polymer with high absorbency under load (AUL). The composite polymer of the invention comprises a synthetic hydrophobic polymer and a natural biopolymer. More specifically, the composite polymer comprises styrene maleic acid copolymer and a biopolymer of animal or vegetal origin in conformity with the technological flow chart presented in <FIG>. Styrene maleic acid copolymer is preferably in salt form, more preferably in the form of monovalent cation salt.

Alternatively, the styrene moiety in the synthetic polymer can be replaced by other hydrophobic moieties. Exemplary synthetic polymers are: poly(maleic anhydride-co-methyl vinyl ether) (Gantrez), poly(vinyl chloride-co-maleic acid) and poly[(maleic anhydride)-alt-(vinyl acetate).

The term "composite" as herein used refers to a polymeric substance that a) is formed from at least two polymers with different macromolecular chemical structure; and b) the resulting composite is a unique entity that does not separate spontaneously to its components during application. It is understood that the term "composite" may include other substances such as drugs, stimulators, inhibitors, odorants, emollients, plasticizer and others.

The term "anionic" refers to a polymeric composite generating in aqueous media a negative electrochemical potential as the result of the presence in its structure of some free acid functional groups capable of dissociating into anions.

In an embodiment of the invention described in <FIG>, the production process starts with the synthesis of copolymer (styrene-alt-maleic anhydride) by bulk co-polymerization using an excess of about <NUM>-<NUM>% of maleic anhydride relative to styrene, whereas maleic anhydride works also as a solvent (operation <NUM>).

Copolymerization is executed in Sigma-type mixer machines named Hermetic machines in order to be able to work at high pressures e.g. not exceeding <NUM> bar or in vacuum conditions (less than 10mbar) with double mantle as well with arms equipped with a heating - cooling system.

The copolymerization process for the production of a superabsorbent polymer uses styrene monomer stabilized with organic compounds that inhibit the process of homopolymerization during storage and transportation. Such inhibitors are for example substances such as : amino derivatives, thiols derivatives, and hydroxyl derivates as for example (<NUM>-hydroxypropyl)-ethylene diamine compounds, <NUM>-tert-butylcatechol and others) being preferred <NUM>-tert-butylcatechol in proportion of <NUM>- <NUM>% to the monomer, more preferably is <NUM>- <NUM>% to the styrene and most preferably <NUM>-<NUM>% to the styrene and the molar fraction of styrene in the reaction mass is <NUM>-<NUM>, preferably <NUM>-<NUM> and more preferably <NUM>-<NUM>.

The copolymerization also contains maleic anhydride that is either fresh maleic anhydride MAnh or recovered maleic anhydride MAnh-R that is recycled from a previous batch as schematically showed in <FIG>. and the amount of fresh maleic anhydride MAnh relative to recovered maleic anhydride MAnh-R is about <NUM> - <NUM>% (dry basis).

For copolymerization are used customary agents as peroxides, azo compounds etc., which form free radicals by thermal decomposition, while the quantity of initiator is <NUM>-<NUM> %, preferably <NUM>-<NUM>% and most preferably <NUM>-<NUM>% to a double quantity of styrene adopted for copolymerization.

Next, it follows the conversion of styrene-alt maleic anhydride copolymer to styrene-alt maleic acid copolymer by hydrolysis with water (process <NUM>) which is done in the same equipment where copolymerization has been made.

Conversion of styrene-alt maleic anhydride copolymer to styrene-alt maleic acid copolymer by hydrolysis using a quantity of water higher than the one stoichiometrical required for total hydrolysis (Ws) with an excess which represents <NUM>-<NUM>% versus to the stoichiometrical value, preferably in excess of <NUM>-<NUM>% to the stoichiometrical water and most preferably <NUM>-<NUM>% in excess to the stoichiometrical water.

The total quantity of water necessary to styrene and maleic anhydride copolymer's hydrolysis is inserted in the mass of reaction in two steps from which <NUM>% is in the form of <NUM>. 005N hydrochloric acid solution and the rest as non-acidulated water.

The acidulated water is inserted into the reaction mass in two portions at a mass reaction's temperature that not exceeding <NUM> at15 minutes intervals between each dosage, and the quantity of non-acidulated water is inserted into the mass of reaction also in two portions, from which the first is after <NUM> minutes from the last portion of acidulated water, then is inserted the last portion of non-acidulated water and mixing of reaction mass for <NUM>-<NUM> minutes in cooling conditions of <NUM>-<NUM>.

Reaction mass resulted after hydrolysis is a wet solid in form of a powdery mass of white color with a value of bulk density of <NUM>-<NUM>/cm<NUM>.

Further , mass of reaction that resulted after copolymerization and hydrolysis (which is a blend of styrene maleic acid copolymer - SMAC and free maleic acid -MAC, which contains traces amounts of non-reacted styrene and stabilizer for styrene as well as traces of hydrochloric acid) is transferred to perform the purification process of styrene maleic acid copolymer (process <NUM>).

The purification process which represents the extraction of free maleic acid fraction from SMAC polymer mass is done in an equipment as tank-type with mixing in which over reaction mass resulted after hydrolysis of synthetic copolymer is added a quantity of deionized water for purification [Wp] that represents a quantity correlated to the wet mass of reactions (RM) in accordance with the relationship Wp= <NUM> * RM or Wp= <NUM> * RM, preferably Wp= <NUM> * RM.

Purification consists of <NUM>-<NUM> extraction stages followed each time by filtration. The number of extraction and filtration operations are established so that the content of the free carboxylic groups found in polymer of SMAC to be between <NUM>-<NUM> mole/gram, preferably between <NUM>-<NUM> mole/gram and most preferably between <NUM>-<NUM> mole/gram.

The extraction in fact occurs at temperature of <NUM> for <NUM> minutes and each filtration (process <NUM>) is done with known equipment as press filter or Nuce filter. All solutions resulted from filtering are collected into a tank of supernatant in order to process the maleic acid which it contain.

Processing of maleic acid water solution to recovery of maleic anhydride consists of the following operations:.

The purified filtrate of SMAC polymer is collected in an equipment as Sigma mixer type in order to be processed with biopolymers to obtain the water soluble composite polymer containing synthetic SMAC polymer and biopolymer [WSPC] (process <NUM>).

The preparation process of polymeric composite [WSPC] containing SMAC and a biopolymer of animal or vegetal origin is preceded by other operations as follows:.

The amount of biopolymer relative to copolymer in composite is <NUM>-<NUM> % (dry basis), preferably <NUM>-<NUM> % (dry basis) and most preferably <NUM>-<NUM> % (dry basis).

The blending of the composite mass continues during <NUM>-<NUM> hours until the polymeric mass is transformed from the viscous solution into a partially dried granular mass with a moisture content not higher than <NUM>%.

This partially dried polymeric composite material WSPC in granular form is subjected to supplementary drying (process <NUM>) at temperatures of <NUM>-<NUM> on conveyor belt type or Rotary type in order to obtain final drying of until the moisture content is less than <NUM>%, preferably less than <NUM>% and most preferably less than <NUM>%.

Further steps of drying, grinding and sieving are carried (process <NUM> + process <NUM>) to obtain two types of solid phases called herein large solid phase (LSP) with granulometric distribution higher than <NUM> microns, preferably of <NUM> -<NUM> microns that corresponds to be used in the manufacture of diapers and a small solid phase (SSF) with granulometric distribution up to <NUM> microns. The small solid phase SSF is re-used in the preparation of the next new batch of SAP who attended the process <NUM>.

Further, the large solid phase LSP is exposed to post-treatment surface coating process using known chemical substances as: glycerin ethylene glycol, propylene glycol or polyether hydroxyl with properties of biodegradability. Examples of preferred coating materials are hydroxyl polyether, more preferably polyethylene glycol - PEG <NUM> used at a rate of <NUM>-<NUM>% by weight (dry basis) to LSP, preferably at a rate of <NUM>-<NUM>% by weight and most preferably at a rate of <NUM>-<NUM>% by weight to LSP.

Surface coating is made in equipments as powder coating machines type at temperature of <NUM>-<NUM>, preferably at temperatures of <NUM>-<NUM> and most preferably at temperatures of <NUM>-<NUM> for <NUM> -<NUM> minutes, preferably for <NUM>-<NUM> minutes and most preferably for <NUM>-<NUM> minutes. As a result of this process is resulted the material called Polymer Composite Coated Treated- PCC (operation <NUM>).

The obtained material after surface coating (Polymer Composite Coated) is subdue to a thermal treatment called first thermal treatment (TT1) (operation <NUM>) consisting in warming of particles mass in hot air with temperature of <NUM>-<NUM> for <NUM>-<NUM> minutes, preferably with temperatures of <NUM>-<NUM> for <NUM>-<NUM> minutes and most preferably by bulk thermal crosslinking at temperatures of <NUM>-<NUM>, for <NUM>-<NUM> minute. using equipment of conveyor belt type or shaking rotary type when is resulted an intermediary material called Polymer Composite Coated first crosslinked (PCC-CL-<NUM>).

The material PCC-CL-<NUM> is subdue to a new thermal treatment (TT2) (operation <NUM>) in hot air with temperature of <NUM>-<NUM> for <NUM>-<NUM> minutes, preferably at temperatures of <NUM>-<NUM> for <NUM>-<NUM> minutes and most preferably to temperature of <NUM>-<NUM> for <NUM>-<NUM> minute in the same type of equipment used for TT1 and is obtained the Polymer Composite Coated second crosslinked (PCC-CL-<NUM>).

The material (PCC-CL-<NUM>) is then conditioned for <NUM> hours in an atmosphere in which the air has a moisture content of <NUM>% and temperature of <NUM> and then is packaged in sealed polyethylene bags (operation <NUM>).

The material resulted after conditioning is a biodegradable SAP with AUL higher than <NUM>/g in aqueous solution of <NUM>% NaCl at pressure of <NUM> psi, which represents the end product of the manufacturing process which is the object of the present invention.

This example shows a representative variant for production of <NUM> biodegradable SAP with high AUL which is within the object of the present invention.

In a Sigma mixer (<NUM>) connected to vacuum, with a heating-cooling mantle, thermometer, and dosing funnel for liquids is inserted <NUM> of maleic anhydride technical grade (MAnh) and <NUM> recovered maleic anhydride (MAnh-R) from a previous batch. The solid mass is heated at temperature of <NUM> under mixing conditions until a homogenous transparent liquid is obtained which represents melted maleic anhydride. Then, <NUM> of styrene containing <NUM> of <NUM>-tert-butylcatechol as stabilizer and <NUM> of benzoyl peroxide (BPO) as initiator (prepared in advance) are added in the mixer by using a dosing funnel at temperature of <NUM>. After about <NUM> minutes from the styrene dosing, the reaction mass returns to a temperature of <NUM>. After about <NUM> minutes at the same temperature begin the process of copolymerization, noted by increase of the temperature of the reaction mass with a speed of <NUM>. 2degree/minute. When the mass of reaction reaches the temperature of <NUM>, the reaction mass is cooled, by using a cooling agent with temperature of -<NUM>, after about <NUM> minutes the reaction mass reaches the temperature of <NUM> and then begins to decrease. In this moment the cooling is stopped and when the reaction mass reaches a temperature of <NUM>, a heating aid is inserted in the mixer's mantle to maintain the temperature of reaction mass at <NUM> for <NUM> minutes. The reaction mass is then cooled to a temperature of <NUM>. From this moment begins the developing of hydrolysis process of the maleic anhydride included in the polymer of SMA and also the free maleic anhydride, both being converted to maleic acid. The hydrolysis process occurs also in Sigma mixer by addition of <NUM> of water in total, from which <NUM> as <NUM>. 05N hydrochloric acid solution in two equal servings at <NUM> minutes interval and the rest of <NUM> as deionized water which does not contain hydrochloric acid, inserted also in two servings at <NUM> minutes interval.

Variation in time of some properties and the aspect of the reaction mass from the moment when begins the copolymerization and to the end of the hydrolysis of the maleic anhydride free and linked to the copolymer SMAC are presented in <FIG>.

Further the whole quantity of wet solid obtained after copolymerization and hydrolysis which represents <NUM> is subdue to a process of separation of the copolymer styrene-alt maleic acid SMAC and its purification by successive extractions and filtrations using a Nuce filter with stirrer. For this purpose, over the quantity of <NUM> of wet reaction mass obtained in Sigma mixer is added <NUM> of deionized water. The washing process occurs at temperature of <NUM> for <NUM> minutes, then the resulted suspension is filtered under pressure of <NUM> atm. It resulted <NUM> of supernatant and <NUM> filtrate. The filtrate as wet solid is subdue to a new extractions with <NUM> of deionized water, the suspensions resulted is mixed at <NUM> for <NUM> minutes. After this second filtration are obtained <NUM> filtrate and <NUM> of supernatant.

Whole quantity of <NUM> supernatant shall be further processed for recovery of maleic acid which it contains and then its converting in maleic anhydride necessary to the new batch of synthetic polymer. After the concentration of supernatant by reverse osmosis from <NUM>% to <NUM>% , further is subdue to atomization to obtain the maleic acid. In the end by thermal dehydration under vacuum (by modifying the method described in <CIT>) are obtained <NUM> of recovered maleic anhydride (MAnh-R].

The wet solid mass of <NUM> that represents the filtrate is transferred in Sigma mixer to prepare the polymeric composite following addition of the biopolymer. This process occurs as follow: in Sigma mixer over <NUM> of wet SMAC is added <NUM>. L of NaOH solution of <NUM>% concentration, and is obtained a quantity of <NUM> of viscous mass that represents styrene maleic acid copolymer as sodium salt of <NUM> % concentration.

Separately in a reaction vessel with stirrer and heating -cooling mantle, <NUM> of gelatin Type A ( Bloom <NUM>) solution of <NUM>% concentration is prepared.

Finally in Sigma mixer is mixed at a temperature of <NUM> for <NUM> hours <NUM> solution of synthetic polymer with <NUM> of gelatin solution to which is added also <NUM> of small solid phase of SAP resulted from a previous batch. Further the homogenous mass from mixer is dehydrating under vacuum of <NUM> mbar for <NUM> hours when its humidity content reaches <NUM> % and the mass has a granular aspect called WSPC (water soluble polymer composite).

Instead of poly(styrene-maleic acid) copolymer, other synthetic polymers are used, for example poly(maleic anhydride-co-methyl vinyl ether) (Gantrez), poly(vinyl chloride-co-maleic acid) and poly[(maleic anhydride)-alt-(vinyl acetate).

The polymeric material WSPC that results after preparation is subdue to a supplementary drying. In this sense occurs the transport of granular mass of partial dried composite to a dryer with pre-heated air at temperature of <NUM>-<NUM> as rotary type and is dried until the humidity content will be less than <NUM>%.

Further the WSPC supplementary dried is grinded and sieved in several steps so in the end are obtained two types of solid phases called big solid phase BSF and small solid phase SSF (with the biggest particle under <NUM> microns). By grinding with conical mills are obtained <NUM> SSF and <NUM> of LSP with the granulometric distribution presented in Table-<NUM>.

The <NUM> of LSP are coated with <NUM> of PEG -<NUM> solution during <NUM> minutes at temperature of <NUM>.

The coated product is subdue to a thermal treatment at temperature of <NUM> during <NUM> minutes (TT1), when is obtained the material PCC-CL-<NUM> which is let to cool until it reaches a temperature of <NUM>. Then is subdue to a second thermal treatment which occurs at temperature of <NUM> for <NUM> minutes. After cooling and conditioning at room temperature are obtained <NUM> SAP.

According to the production process presented in this example has been done <NUM> batches to test the reproducibility of the technology. The results of the technical characteristics of SAP materials resulted in conformity with the present invention are shown in Table-<NUM>.

The test methods are in conformity with ISO <NUM>-<NUM>.

This example presents the biodegradation test of SAP material obtained in Example -<NUM> by using as biodegradation medium the municipal compost.

The objective of this experiment is to evaluate the biodegradability of the two polymers - SAP material obtained by the method of the present invention as disclosed in Example <NUM> and just for ease of comparison, referring in this example and in <FIG> as to EBS and commercial SAP material polyacrylate based. The test will be based on the proposed new guideline by the Organization for Economic Cooperation and Development (OECD <NUM>) and on the US EPA OPPTS guideline <NUM>. The test, CO<NUM> in sealed vessels (headspace test), is suitable for testing insoluble substances [Organization for Economic Cooperation and Development (OECD) (October <NUM>): Proposal for a new guideline <NUM> for Testing of Chemicals: Ready biodegradability - CO<NUM> in sealed vessels (Headspace test).

When testing for the ultimate biodegradability of insoluble substances or substances for which a homogenous solution cannot be obtained, the methods of choice are the respirometric methods where CO<NUM> evolution or O<NUM> consumption are measured. The present test is based on measurement of CO<NUM> produced during the ultimate biodegradation of the tested substances. The test substance, at approximately 20mgC/L, as the sole source of carbon and energy, is incubated in a buffer-mineral salts medium which has been inoculated with a mixed population of microorganisms. The test is performed in sealed bottles with a headspace of air, which provides a reservoir of oxygen for aerobic biodegradation. The CO<NUM> evolution, resulting from the ultimate aerobic biodegradation of the test substance, is determined in the test bottles in excess of the CO<NUM> produced in the blank vessels containing inoculated medium only. The CO<NUM> values are translated to equivalent inorganic carbon (IC) produced and the extent of biodegradation is expressed as the percentage of the maximum theoretical IC (ThIC) production, based on the quantity of test substance (as organic carbon) added initially. A few controls are run in parallel: (<NUM>) Blank control, containing inoculum and mineral medium, but no test compound, (<NUM>) Procedure control , containing a reference biodegradable substance (sodium benzoate) and, (<NUM>) Inhibition controls, containing both the test and reference substances, in order to check possible inhibition to the microorganisms, and (<NUM>) abiotic controls, where the inoculum is poisoned by mercuric chloride (HgCl<NUM>).

The test is normally run for a period of <NUM> days but may be prolonged if degradation has begun by day <NUM>. Biodegradation of > <NUM>% ThIC within a '<NUM>-d window' (the <NUM> days following the attainment of <NUM>% biodegradation) in the test, demonstrates that the test substance is readily biodegradable under aerobic conditions.

The substances to be tested are the two super absorbent polymers Experimental Bio SAP (EBS) and commercial polyacrylate superabsorbent polymer (SAP). Elemental analysis of the polymers will be performed in order to determine carbon content.

The substances to be tested are the two super absorbent polymers EBS that is the composite polymer of the present invention and commercial SAP. Elemental analysis of the polymers will be performed in order to determine carbon content.

In order to check the functional capability of the activated sludge and the possible inhibitory effect of the polymers, a control with a reference substance will be run in parallel. The reference substance that will be used is sodium benzoate (C<NUM>H<NUM>NaO<NUM>). Water for dilutions will be prepared by sparging overnight distilled water at pH <NUM> with CO<NUM> free air. The CO<NUM> free air will be prepared by passing air through soda lime pellets.

Mineral medium will be prepared from the stock solutions (a), (b), (c), (d).

The inoculum will consist of activated sludge collected at a Haifa Municipal Wastewater Treatment Plant. In order to reduce CO<NUM> background levels, the sludge will be aerated for a few days (no longer than <NUM> days) before using it for the test.

Aliquots of <NUM> inoculated medium will be dispensed into replicate bottles of <NUM>-ml capacity, leaving a headspace of <NUM>. The number of bottles in each set will be such that at each sampling time, three bottles can be sacrificed.

Following acidification of the medium (<NUM>. <NUM>), a sample of <NUM> will be withdrawn from the headspace and injected into the gas chromatograph (GC) for the determination of CO<NUM> concentration. The sampling schedule will depend on the lag period and rate of biodegradation of the test substance. Three bottles will be sacrificed for analysis on each day of sampling, which will be approximately once every <NUM> days. The test should normally run for <NUM> days but might be prolonged if degradation has begun by day <NUM>. Bottles representing the inhibition and abiotic controls will be sampled only on day <NUM> and <NUM> (or last day).

Assuming <NUM>% mineralization of the test substance to CO<NUM>, the maximum IC production (ThIC) in excess of blank production equals the amount of total organic carbon (TOC) contributed by the test substance added to each bottle. The total mass of inorganic carbon (TIC) in each bottle is the summation of the mass in the liquid and the mass in the headspace. Since the standards were prepared from defined IC solutions that were acidified and treated like the test samples, each standard represents a specific carbon concentration in solution after equilibration with gaseous phase. Consequently, the TIC mass in the reaction mixtures equals the carbon concentration value obtained by the GC analysis multiplied by the liquid volume.

The percentage of biodegradation (%D) is given by the following equation: <MAT> where:.

The results from the first five days of the test are presented in Table <NUM>. In the procedure control, a net <NUM>% of carbon was released as CO<NUM>. In the EBS test, <NUM>% of carbon was released as CO<NUM> while in the SAP test there was not net release of CO<NUM>. It should be mentioned that at this point, the amount of CO<NUM> released in the SAP samples was less than the amount released by the blank control where the background CO<NUM> production by the inoculum was measured.

ThIC concentrations are calculated from average weight of polymers introduced in the bottles sacrificed at the specific time points - Average production of CO<NUM> from the same sacrificed bottles was translated to IC according to calculations Percent degradation was calculated after deduction of blank. NA - not applicable.

The evolution in time of the biodegradation test is presented in the images shown in <FIG>.

This example presents a biodegradation test of SAP prepared as in example-<NUM> except that the gelatin content is <NUM>% and the biodegradation medium used are the soils extract.

We have tested the biodegradability of the heteropolymer polystyrene-maleic anhydride-gelatine (SMA-G) after incubation with <NUM> bacterial cultures.

a) Biodegradation of gelatine
b) The data in Table <NUM> shows that the major part of the gelatine was degraded by the bacteria after <NUM> week. Only trace amounts of protein could be detected after <NUM> weeks.

The data in Table <NUM> shows that more than <NUM>% of the polymer was degraded by the bacteria after incubation of <NUM> weeks.

This example presents a test of biodegradation for SMA-sodium salt using Pseudomonas bacteria which is very abundant in the nature. There has been prepared a solution of SMA-sodium salt in which has been inoculated Pseudomonas bacteria using the experimental protocol from Niall D. O'Leary et al (<NUM>). The solution has been maintained during <NUM> days without agitation in the presence of air and light to mimic an environmental phenomenon. It has been taken samples from this solution and studied in time by spectrophotometry UV-VIS. The results are presented in <FIG>. It can be seen a band on UV zone below of <NUM> which is attributed to an aromatic ring as phenyl acetic acid. The intensity it goes up with the increase in time. The phenylacetic acid is not an aggressive substance to both the environment and humans. In <FIG> is presented the scheme of the biodegradation mechanism.

Claim 1:
A biodegradable polymeric composite represented by the formula:<MAT> wherein:
SMAC- represents a styrene maleic acid copolymer in acid form and/or anionic with a neutralization of the SMAC copolymer of <NUM>-<NUM> % and leading to a solution of the copolymer salt with a concentration higher than <NUM>%;
D represents a counterion when SMAC is in anionic form;
B represents a biopolymer selected from a protein, soybean protein, collagen, collagenic biopolymer, gelatin, collagen hydrolysate, albumin, guar or starch and casein,
S represents coating agent selected from glycerin, ethylene glycol, propylene glycol, polyethylene glycol or polyether hydroxyl
W represents water bonded to the composite;
the polymeric composite having an absorbency under load (AUL) that is higher than <NUM>/g in aqueous solution of <NUM>% NaCl at pressure of <NUM> psi (<NUM> Pa).