EP0000247B1 - Water-absorbent starch copolymerisates and method for their preparation. - Google Patents

Water-absorbent starch copolymerisates and method for their preparation. Download PDF

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Publication number
EP0000247B1
EP0000247B1 EP78300036A EP78300036A EP0000247B1 EP 0000247 B1 EP0000247 B1 EP 0000247B1 EP 78300036 A EP78300036 A EP 78300036A EP 78300036 A EP78300036 A EP 78300036A EP 0000247 B1 EP0000247 B1 EP 0000247B1
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Prior art keywords
starch
ethylenically unsaturated
water
copolymerised
copolymerisate
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German (de)
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French (fr)
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EP0000247A1 (en
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Austin Harry Young
Frank Verbanac
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Primary Products Ingredients Americas LLC
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Tate and Lyle Ingredients Americas LLC
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F251/00—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof

Definitions

  • This invention relates to water-absorbent starch copolymerisates.
  • water-absorbent starch compositions are also deficient in certain other properties which are essential and desirable for many end-usages (e.g., lack adhesiveness, prefabrication and shaping, film-forming, bonding, coating, etc. properties). This generally restricts their usage to limited areas of application (e.g., separately contained by a water-permeable enclosure or separately added or mixed to another substrate).
  • these water-absorbent starches cannot be effectively used at high-solid coating levels or be readily affixed or bonded to a carrier or substrate or easily provided in a preformed shape.
  • French Patent 2305452 discloses water-absorbent resins which are copolymers of
  • An object of the invention is to provide a simple and reproducible method for preparing water-absorbent starch compositions. Another object is to obtain water-absorbent starch compositions which in comparison to existing water-absorbent starches have improved versatility, utility and functional properties. A further object is to provide a method for applying or affixing water-absorbent starches to carriers or substrates or preparing preformed products and the products thereof.
  • a starch copolymerisate capable of absorbing several times its own weight of water comprising the copolymerisate product of ethylenically unsaturated starch molecules and ethylenically unsaturated monomers with the ethylenically unsaturated monomers forming a connective polymeric linkage between the copolymerised starch molecules characterised in that the copolymerisate is made up of a non-linear lattice of a plurality of starch chains linked together by polymeric linkages represented by the formula: wherein Y represents a starch chain of D-glucose units or a hydrolysed or derivatised starch chain, Z represents an organo group which links the group to the carbon atom of the starch chain by a sulphur atom or an oxygen atom, R is hydrogen or a monovalent organic radical, M represents a plurality of copolymerised ethylenically unsaturated monomers with "p" representing the
  • the water-absorbent starches or their precursors may be prepared by a copolymerisation process which comprises copolymerising:
  • n' integer and the particular "W" or “W” precursors which are used in the copolymerisation process may vary considerably. Some of the monomers will contain "W” or "W” precursors (e.g., n' has a value of 1 to 3) while others may be free from the "W” or "W” precursor moieties (e.g., n' is 0). Similarly, the copolymerised monomers may be essentially comprised of monomers which contain the "W" or "W” precursors.
  • M' may be comprised of an ethylenically unsaturated portion of an organic group of the same chemical composition, or a mixture of different copolymerised monomers in which the M' group differs in composition.
  • the "W” or “W” precursors may be the same or different in type. The amount of "W” monomer or “W” monomer precursors copolymerised with the starch is maintained at a level sufficient to impart water-absorbency to the copolymerised starch product. If "W" precursors are solely used, then it is necessary to convert a sufficient number of precursors to the water attractant form to achieve the desired water-absorbent, starch copolymerisate product.
  • the present starch copolymerisates are more versatile and useful. They may be prefabricated from water-soluble or water-dispersible, modified or hydrolysed starches into high-molecular-weight and cross-linked, water-absorbent starch copolymerisates.
  • the ethylenically unsaturated starches used herein are most typically provided in a water-soluble form or may be easily converted to such a form. This renders the present invention particularly applicable to prefabricating operations wherein water or aqueous systems are used to disperse, dissolve or plasticise the starch.
  • the invention therefore is ideally suited for most prefabricating operations (e.g., coating, moulding, casting, extrusion, drying, sheeting, printing, bonding, encapsulating, gelling, impregnating, laminating, plasticising, etc.) wherein the starch is initially provided in a form most suitable for prefabrication (e.g., liquid, pliable, mouldable, etc.) and then preformed and converted into a solid object.
  • prefabricating operations e.g., coating, moulding, casting, extrusion, drying, sheeting, printing, bonding, encapsulating, gelling, impregnating, laminating, plasticising, etc.
  • the starch portion of the ethylenically unsaturated starch chains may be derived from a variety of starch sources, including cereal, leguminous, tuber starches.
  • Illustrative starches include tapioca, corn, high amylose, sweet potato, waxy maize, canna, arrowroot, wheat, sorghum, waxy sorghum, waxy rice, soya, rice, pea, amylose or amylopectin fractions, combinations thereof and the like.
  • the starch amylose content affects the temperature at which a starch will convert to a water-dispersible or starch paste form.
  • the high amylose starches typically require elevated temperatures and pressures (e.g., extrusion, jet cooking, etc.), for uniform dispersal into aqueous systems.
  • starches of a lower amylose content e.g., 30% by weight amylose or less
  • Prepasted or pregelled starches of an amylose content of less than 30% by weight normally disperse into water at an ambient temperature (e.g., 23°C).
  • starch chain For many prefabricates, it is advantageous to modify or alter the starch chain to achieve a more functional and versatile starch product. This may be accomplished by derivatising the starch chains, so that they contain other substituents (e.g., esters or ethers which may contain cationic, anionic, non- ionic, amphoteric, etc. groups).
  • substituents e.g., esters or ethers which may contain cationic, anionic, non- ionic, amphoteric, etc. groups.
  • the ethylenically unsaturated starches may be provided in the pregelled or prepasted form or hydrolysed (e.g., chemical or enzymatic hydrolysis of granular or non- granular ethylenically unsaturated starches) to improve upon their dispersibility into aqueous systems ethylenically unsaturated dextrins, maltodextrins and other low viscosity imparting ethylenically unsaturated hydrolysates (e.g., D.E. 0.2 to 30), are particularly well suited for coating applications.
  • hydrolysed e.g., chemical or enzymatic hydrolysis of granular or non- granular ethylenically unsaturated starches
  • Such ethylenically unsaturated starch hydrolysates provide a means for achieving a high-solids and low viscosity system which is particularly well suited for aqueous coating and prefabricating applications. Modification, derivatisation or hydrolysis of such starches may be accomplished prior or after its derivatisation to the ethylenically unsaturated form.
  • Ethylenically unsaturated starches which contain hydrophobic substituents may be used but will typically require a dispersant.
  • Water-miscible, organo dispersants such as alkanols (e.g. methyl, ethyl, isopropyl, or butyl-alcohol), polyhydric alcohols (e.g. glycerol, ethylene glycol), ethers, (e.g.
  • emulsifiers e.g., see McCutcheon's Detergents and Emulsifiers-North American Edition-1975
  • hydrophilic starches which will uniformly disperse into water at temperatures above the starch gelation point without the aid of water-miscible organo dispersants or surfactant systems.
  • Hydrophilic starches characterised as yielding a centrifugal starch residue of less than 25% by weight (preferably less than 10% by weight) upon immersion in water (one part by weight ethylenically unsaturated starch/100 pbw water) for one hour at temperatures above their gelation point and centrifugation at 103 g's for 10 minutes are most suitably used to coating and prefabricating applications.
  • Hydrophilic ethylenically unsaturated starches containing pendant ethylenically unsaturated groups with polar moieties or substituents to impart hydrophilicity to the unsaturated portion of the starch molecule are especially useful.
  • the water-dispersible, ethylenically unsaturated starches herein may be prepared by a variety of starch derivatisation processes.
  • Derivatisation processes which may be used to produce appendant, monoethylenically unsaturated groups include reacting alkali metal starch or hydroxyethylated starch salts with an allyl propiolate to provide carboxylated vinyl starch ether; reacting starch with ethylenically unsaturated organic carboxylic anhydrides (e.g., methacrylic anhydride, etc) or organic allyl halides (e.g.
  • allyl bromides allyl chloroformates
  • epoxides e.g., butadiene monoxides, etc.
  • the most suitable monoethylenic unsaturated starches are the starch esters of alpha, beta ethylenically unsaturated carboxylic acids (e.g., acrylate, methacrylate, crotonate, citraconate, itaconate starch esters as well as alkali salts and amides thereof, mixtures thereof and the like); N-allyl carbamate starch esters (e.g., Starch glycidyl methacrylate and glycidyl acrylate starch ethers (e.g., see U.S.
  • allyl starch ethers e.g., allyl, isopropenyl, etc.
  • allyl alkyl starch ethers e.g., ethyl, propyl, butyl, etc. starch ethers
  • allyl alkylene oxide starch ethers e.g., allyloxyalkyl starch ethers (e.g., the allyl oxyethyl, oxypropyl and oxybutyl, etc. starch ethers)
  • allyloxy hydroxyalkyl starch e.g., 3 - allyloxy - 2 - hydroxy-propyl starch, etc.
  • starch acrylamides etc.; combinations thereof and the like.
  • the ethylenically unsaturated starches comprise those starches which will readily and uniformly copolymerise with the bridging comonomers.
  • Ethylenically unsaturated starches which contain polar groups immediately juxtapositional to the unsaturated group and which activate the copolymerisability of the double bonds in the presence of free-radical initiating systems are particularly well suited for this purpose.
  • Such ethylenically unsaturated starches may be represented by Formula III: wherein starch is a starch chain of D-glucose units, E represents an activating polar group juxtapositional to the ethylenic unsaturation, D is sulphur or oxygen, Q is an organo group which divalently joins the D group to the activating polar group, R represents a monovalent group and "a" represents the D.S. (i.e., the number of appendant ethylenic unsaturated groups per anhydroglucose unit of said starch chain).
  • Typical juxtapositional activating polar groups i.e., E
  • Typical juxtapositional activating polar groups include carbonyl thiocarbonyl groups and the like.
  • the ethylenically unsaturated portion of the starch chains are most typically comprised of appendant groups which individually have a molecular weight of less than 500 with those having an appendant molecular weight of greater than 50 but less than 300 (preferably from 75 to 150 M.W.) being most typical.
  • the E group contains a radical
  • R' is a hydrogen atom or a mono-organo group which is joined directly to the nitrogen atom by a monovalent bond.
  • Q may be any divalent organo group which joins the activating radical to the starch chain e.g., linked to D and acrylamide nitrogen atoms via carbon linkages.
  • the starch oxygen or sulphur atom and activating radical may be directly linked together by a single carbon atom or by an organo group which is comprised of a plurality of carbon atoms.
  • the -Q- group may be comprised of substituted or unsubstituted, straight or branched aliphatic groups (e.g.
  • alkylene substituted or unsubstituted, arylene group (e.g., naphthlene, phenylene, etc.) as well as divalent organo groups which contain carbon to non-carbon atom linkages (e.g., organo ethers and thioethers, sulphonyl, N-methylene substituted secondary and tertiary amines (such as a -CH 2 N(H)-Q- radical).
  • the Q group-linking chain may also contain other substituents such as carbonyl, carboxylate, thiocarbonyl, etc.
  • radicals as well as monovalent radicals such as hydroxy, halo (e.g., Br., F., CI and I), alkyl, aryl, hydroxyalkyl, hydroxyaryl, alkoxy, aryloxy, carboxyalkyl, carboxyaryl, amine substituents, combinations thereof and the like.
  • the divalent Q organo group will contain less than 10 carbon atoms and preferably no more than 7 carbon atoms.
  • R' and R may be a mono-organo or hydrogen substituent.
  • the R' and R mono-organo groups may also contain an ester, ether, carboxylic organo acid, alcohol, hydrocarbyl (e.g., alkyl, aryl, phenyl, etc.) as well as divalent organo groups containing non-carbon atoms to carbon chain linkages (e.g., such as oxy, sulphonyl, thio, carbonyl groups, etc. as mentioned above with respect to Q).
  • R' and R are either H or a substituted or unsubstituted mono-organo group containing less than 8 carbon atoms such as a lower alkyl or phenyl group.
  • Illustrative substituted mono-organo groups are halo substituted alkyl and phenyl, alkoxy, aryl, phenoxy, phenol and alkanol and correspondingly thiols, alkanoic, phenoic, tolyl, benzoyl, carboxy, sulphoalkyl, sulpho-phenyl, combinations thereof and the like.
  • R' and R are either hydrogen or a 1-5 carbon alkyl radical (preferably methyl) and "a" has a value of at least 0.002.
  • the most preferred ethylenically unsaturated starches are the starch acrylamides represented by Formula IV: D is as defined above (preferably oxy), Q 1 represents a divalent organo group such as Q as defined above, "a” represents the degree of substitution, R and R' are monovalent groups as defined herein and "na" is 0 or 1.
  • the aforementioned Formula IV starch acrylamides may be prepared by reacting N-methylol acrylamides with starch in the presence of an acid or acid generating catalyst and a polymerisation inhibitor as illustrated by the following etherification equation V: wherein "a" of reactants (A) and (B) represents the number of starch hydroxyl groups of (A) etherified with the N-methylol acrylamide reactants (B), R' and R are mono-organo or hydrogen groups such as defined below, and H + represents an acid or acid generating etherifying catalyst.
  • N-methylol acrylamide reaction V may also be used to prepare a starch acrylamide reaction product (C) wherein Q as illustrated in Formula III contains an alkylene oxy or arylene oxy group by reacting the corresponding hydroxyaryl or hydroxyalkyl starch ethers (e.g., hydroxypropyl and hydroxyethyl starch ethers) with an N-methylol acrylamide wherein R' and R represent a monovalent group.
  • Q as illustrated in Formula III contains an alkylene oxy or arylene oxy group by reacting the corresponding hydroxyaryl or hydroxyalkyl starch ethers (e.g., hydroxypropyl and hydroxyethyl starch ethers) with an N-methylol acrylamide wherein R' and R represent a monovalent group.
  • Substituted acrylamides which contain a reactive N-methylol group linked to the acrylamide nitrogen atoms by intervening divalent Q organo groups and starches containing cationic and anionic or ionic acrylamide substituents may be obtained by etherifying a starch with the appropriate N-methylol acrylamide (e.g. sodium - 2 - N - methylol acrylamido - 2 - methylpropanesulphonate, a N-methylol acrylamide quaternary ammonium halide such as 3 - (N - methylol acrylamido) - 3 - methyl butyl trimethyl ammonium chloride, etc.).
  • N-methylol acrylamide e.g. sodium - 2 - N - methylol acrylamido - 2 - methylpropanesulphonate, a N-methylol acrylamide quaternary ammonium halide such as 3 - (N
  • R' substituents in V above include hydrogen, N-arylol, the N-alkylamines and N-arylamines such as N-methylol; N-ethyl-; N-isopropyl-; N-n-butyl-; N-isobutyl-; N-n-dodecyl-; N-n-octadecyl-; N-cyclohexyl-; N-phenyl; N - (2 - hydroxy - 1,1 - dimethylpropyl)-; N-p-hydroxybenzyl-; N - (3 - hydroxybutyl)-; N - (4 - hydroxy - 3,5 - dimethylbenzyl)-; N - (2 - hydroxy - 1,1 - dimethylethyl)-; N - (2 - hydroxyethyl)-; N - (5 - hydroxy - 1 - naphthyl)-; combinations thereof and the like.
  • Illustrative acrylamide reactants (B) include N-methylol and N-thiomethyl acrylamides such as N - (hydroxymethyl) acrylamide; N - (hydroxymethyl) - N - [(1 - hydroxymethyl)propyl] acrylamide; N - (hydroxymethyl) - 2 - alkyl acrylamides, (e.g., N - (hydroxymethyl) - 2 - (methyl - heptyl) acrylamide; M - [(1 - hydroxymethyl) - 1 - nonyl] - 2 - methyl acrylamide; N - (1 - hydroxymethyl) - 2 - methyl acrylamide; N - (hydroxymethyl) - 2 - propyl acrylamide; etc.); N - (mercaptomethyl) acrylamide; N - methylol - N - isopropyl acrylamide; 3 - (N - methylol acrylamido) - 3 -
  • Reaction V may be suitably conducted in the presence of known acid or acid-generating catalysts (e.g., ammonium chloride or phosphate, mono-ammonium acid phosphate, zinc chloride, etc.), preferably at a temperature from 70°C to 95°C until the desired D.S. level is achieved.
  • acid or acid-generating catalysts e.g., ammonium chloride or phosphate, mono-ammonium acid phosphate, zinc chloride, etc.
  • Conventional polymerisation inhibitors e.g., hydroquinone, its derivatives, 2,5-di-t-butylquinone, etc.
  • the starch acrylamides may be prepared via solution, slurry, dry, semi-dry or other appropriate condensation processes. To prepare a starch-acrylamide having a D.S.
  • Uniform dispersal of the N-methylol-acrylamide reactant, catalyst and polymerisation inhibitor throughout the starch may be effectively accomplished by initially forming a starch slurry or treating the starch with an absorbable dispersant media (e.g., water) in which the acrylamide, catalyst and polymerisation inhibitor are soluble or placed in mobile form and thereafter imbibing or absorbing the dispersant and its solutes into the starch granules.
  • an absorbable dispersant media e.g., water
  • ethylenic unsaturates for optimum water-absorbency will depend upon the starch chain type.
  • An ethylenically unsaturated monoglucoside will typically require at least a D.S. of 2.0 or more, whereas long chain starch chains (e.g., unhydrolysed starch) typically require a considerably lower D.S. level (e.g., 0.0002) to be water-absorbent.
  • D.S. for any given starch chain and the optimum water-absorbency which may be achieved from the starch copolymerisate thereof.
  • a starch copolymerisate which is capable of absorbing several times its own weight can be typically obtained by copolymerising a starch which has an ethylenic unsaturation ranging from 0.002 D.S. to 0.10 D.S. Higher ethylenic unsaturated D.S. levels (e.g, 0.2 or higher) will usually require more carefully controlled copolymerisation conditions with an appropriate proportion of ethylenically unsaturated monomers and type of monomer.
  • Starch copolymerisates which typically absorb more than 10 times their weight in water are obtained from starches having an ethylenic unsaturation ranging from 0.005 D.S. to 0.05 D.S.
  • starch substrates which contain appendant ethylenic unsaturation at a level ranging from 0.005 D.S. to 0.01 D.S.
  • the starch copolymerisate water-absorbency properties are directly related to its lattice (i.e., molecular configuration) and its ionic hydrophilicity.
  • the characteristics of the starch chain and the polymeric linkages formed by the interpolymerised ethylenically unsaturated monomers primarily dictate the copolymerisate lattice structure. Failure to achieve proper polymeric linkage or bridging between starch molecules will adversely affect the water-absorbency properties of the starch copolymerisate. Excessively long polymeric monomer linkages tend to result in an excessively open structure which adversely affects the water-absorbency character of the starch copolymerisate lattice.
  • the copolymerised ethylenic unsaturated monomers i.e., -[M]p ' of Formula I
  • hydrophilic substituents include cationic, anionic, nonionic, ampholytic, zwitterionic, amphoteric moieties, mixtures thereof and the like. As mentioned above, it is unnecessary for each copolymerised monomeric unit to be a water-attractant group.
  • a significant portion of the polymeric chain units may be free from ionic substituents with the balance of the units providing a sufficient level of "W" substitution to render the starch copolymerisate water-absorbent.
  • the degree of "W" substitution necessary to achieve a water-absorbent starch copolymerisate will depend upon a multiplicity of factors. Factors such as the ionic charge and type of ionic substituents, proportions of ethylenically unsaturated starch to monomer, hydrophilicity and polarity of the copolymerised monomer units, etc. affect the required "W" substitution level. For most application, it is advantageous for the starch copolymerisate to contain either anionic or cationic substituents.
  • a variety of conventional ethylenically unsaturated monomers which contain either the water- absorbtive substituents or its precursors may be used to prepare the starch copolymerisates herein.
  • the polymeric linkages may be amphiphilic (i.e., contain both polar water-soluble and hydrophobic water-insoluble groups).
  • Anionic monomers include ethylenically unsaturated monomers which contain acid groups or acid-salt groups or acid-salt precursors.
  • Exemplary anionic substituents include carboxylates, oxalates, benzoates, phosphonates, maleates, malates, phthalates, succinates, sulphate, sulphonates, tartrates, fumarates, mixtures thereof and the like.
  • Illustrative ethylenically unsaturatEd cationic monomers include nitrogen-containing cations such as primary, secondary and tertiary and quaternary ammonium compounds; sulphur containing cations such as sulphonium salts, halides, etc. phosphoros containing cations such as phosphonium salts; mixtures thereof and the like.
  • Typical nitrogen containing cations include monomers represented by the formula: wherein M' represents an ethylenically unsaturated organo group, R a , R b and R c represent at least one hydrogen atom or organo group, and X is an anion (e.g.
  • R a , R b and R c mono-organo groups include substituted and unsubstituted alkyl, mono- heterocyclic (e.g. piperidine, morpholine, etc.), hydroxyalkyl, aralkyl, cycloalkyl groups as well as cyclic and heterocyclic groups divalently bonded to the nitrogen atom (e.g., R a and R b form a cyclic structure).
  • the preferred nitrogen containing ethylenically unsaturated cationic monomers are the water-soluble, monomeric salts such as the lower alkyls of 1-5 carbon atoms (e.g.
  • ethyl, methyl, propyl polyoxyalkylene (e.g. polyoxyethylene and polyoxypropylene), mixtures thereof and the like; alkoxy (e.g. methoxy, ethoxy, propoxy, etc.); hydroxyalkyl and polyhydroxyalkyl (e.g. hydroxyethyl, hydroxypropyl, dihydroxypropyl, dihydroxybutyl); heterocyclic amines (e.g. morpholine); amines and amides bearing monoorganics; mixtures thereof and the like.
  • the sulphur and phosphorus containing cationic monomers are similar to the aforementioned except either the phosphorus atom or sulphur atom replaces the nitrogen atom.
  • the preferred phosphorus and sulphur cations are the phosphonium and sulphonium cationic salts.
  • Representative cationic monomers include the N-methylol acrylamide reactants mentioned above, dimethylaminoethyl methacrylate; t-butylaminoethyl methacrylate; 2 - hydroxy - 3 - methacryloxypropyl trimethyl ammonium chloride; allyl - trimethyl - ammonium chloride; S - allyl - thiuronium bromide, S - methyl(allyl - thiuronium) methosulphate, diallyl - dibutyl - diammonium chloride, diallyl - dimethyl - ammonium methosulphate, dimethallyl - diethyl - ammonium phosphate, diallyl - dimethyl - ammonium nitrate, S - allyl - (allyl - thiuronium) bromide N - methyl(4 - vinylpyridinium) methosulphate, N - methyl(2
  • anionic monomers include vinyl sulphonic acid and vinyl sulphonates (e.g. see U.S. Patent Nos, 3,970,604, by G. Wentworth and 2,859,191 by Turnbull, etc.); allyl sulphosuccinic acid and allyl sulphosuccinates (e.g. see U.S. Patent Nos. 3,219,608 by Ingleby et al.); sulpho esters of alpha-methylene carboxylic acids and salts thereof (e.g. see U.S. Patent No. 3,024,221 by LeFevre et al.); sulpho-organic esters of fumaric and maleic acids and salts thereof (e.g.
  • acrylic acid methacrylic acid, ethacrylic acid, propacrylic acid, butacrylic acid, itaconic acid, monoalkyl esters of itaconic acid, crotonic acid and crotonates, fumaric acid and fumarates, etc.), mixtures thereof and the like.
  • the water-absorbent starches may be prepared by initially copolymerising the starch with ethylenically unsaturated comonomers which contain reactive sites (e.g. polar or unpolymerised ethylenic unsaturation) which are then derivatised to "W" moieties.
  • the ethylenically unsaturated starches herein may be copolymerised with unsaturated precursors and converted to the anionic form such as by saponification to replace the alkyl ester group with a metal salt, and known techniques of derivatising organic compounds to acidic or the neutralised acid-salt form.
  • the starting monomers contain the hydrophilic structure or one which can be directly converted to its "W" form by neutralisation. This will avoid the derivatisation step as well as the possibility of contaminating the copolymerisate with salts and minerals, and the need to wash and refine to remove such contaminants therefrom.
  • the polymeric linkages between copolymerised starch chains may be comprised of interpolymerised ionic monomeric units and monomeric units free from "W" substituents.
  • the interpolymerised monomeric units free from "W” substituents may be selected from a broad range of ethylenically unsaturated monomers. Hydrophilic and/or hydrophobic comonomers may be used for this purpose.
  • Illustrative interpolymerised comonomers include vinyl aromatics (e.g.
  • styrene and styrene derivatives the alkyl esters of alpha, betaethylenically unsaturated acids; the alpha, beta-ethylenically unsaturated nitriles, alpha, betaethylenically unsaturated amides; vinyl halides (e.g. vinyl chloride and bromide), olefins such as mono- and di-olefins; vinylidene halides (e.g. vinylidene chloride and bromide), vinyl esters (e.g. vinyl acetate and derivatives); diesters of alpha beta-ethylenically unsaturated dicarboxylic acids (e.g.
  • alkyl vinyl ethers such as methyl or ethyl vinyl ether, etc.
  • alkyl vinyl ketones e.g. methyl vinyl ketone, etc.
  • the polymeric linkages are advantageously predominantly comprised of polar or water-soluble monomeric units.
  • Illustrative polar or water-soluble comonomers free from "W" substituents which may be copolymerised with the "W" monomers and the starch include the hydroxyalkyl esters of alpha, beta-ethylenically unsaturated carboxylic acids such as hydroxyethyl, hydroxyethoxyethyl, hydroxymethyl, 2,3 - dihydroxypropyl acrylates and methacrylates, di(2,3 - dihydroxypropyl) fumarate, di(hydroxyethyl) itaconate, ethyl hydroxyethylmaleate, hydroxyethyl crotonate, mixtures thereof and the like; the lower alkyl esters of alpha, beta-ethylenically unsaturated carboxylic acids (e.g.
  • C, to C 2 alkyl ester of mono- and di-carboxylic acid such as methyl and ethyl ester of acrylic, methacrylic, itaconic, fumaric, crotonic, maleic, etc.
  • N - (3 - methylamino) propyl methacrylate 1 - butyl - aminoethyl methacrylate; di-methylaminoethyl methacrylate; beta - (5 - butylamino)ethyl acrylate; 2 - (1,1,3,3 - tetramethylbutylamino) ethyl methacrylate, etc.
  • alpha, beta-ethylenically unsaturated nitriles e.g.
  • alpha, beta-ethylenically unsaturated amides e.g.
  • acrylamide and the N-substituted acrylamides such as N-methyl, N-ethyl, N-propyl, N-N-dimethyl and N-N-diethyl, N-butyl, etc.
  • vinyl esters e.g.
  • vinyl acetate, etc. vinyl alcohol and vinyl ethers (e.g. methyl or ethyl vinyl ether, diethylaminoethyl vinyl ether, diethylaminoethyl vinyl sulphide, 5-aminopentyl vinyl ether, 3-aminopropyl vinyl ether, 2-aminoethyl vinylether, N-methylaminoethyl vinyl ether); alkyl vinyl ketones (e.g. methyl vinyl. ketone, etc.); vinyl pyridine, vinyl pyrrolidone, mixtures thereof and the like.
  • vinyl ethers e.g. methyl or ethyl vinyl ether, diethylaminoethyl vinyl ether, diethylaminoethyl vinyl sulphide, 5-aminopentyl vinyl ether, 3-aminopropyl vinyl ether, 2-aminoethyl vinylether, N-methylaminoethyl vinyl ether
  • the proportions of ethylenically unsaturated starch copolymerised with the ethylenically unsaturated monomers should typically be sufficient to provide a starch copolymerisate which is capable of absorbing at least 10 times its dry weight in water.
  • the monomer type and starch type will affect the proportions needed to achieve optimum water-absorbency. In general, the monomer dry weight will usually fall within the range of 5 to 2000 parts by weight for each 100 parts by weight of the ethylenically unsaturated starch.
  • the water-absorbent starch copolymerisates are advantageously prepared under aqueous polymerisation conditions. Homogeneity of the reactants throughout the aqueous phase results in more uniform and reproducible water-absorbent properties. Ethylenically unsaturated starch and ethylenically unsaturated monomer systems which provide homogeneous dispersions essentially free from centrifugal residue and/or supernatent (e.g.
  • a relatively high monomer and starch to water weight ratio (5:1 to 9:1) is typically used.
  • incompatibility of the ethylenic unsaturated monomer starch system can arise. Elevated fabricating temperatures and pressures may be used to improve upon the compatibility of this system.
  • water-miscible solvents in which the ethylenic unsaturated monomers are soluble e.g. such as glycerol
  • emulsifying agents may be effectively utilised to enhance the water- dispersibility of the monomer-starch system into the aqueous phase.
  • a sufficient amount of water (with or without conventional starch plasticisers) to convert the polymerisable mass to a molten plasticised mass at elevated temperatures (e.g. 80° to 250°C) and pressures is used.
  • the molten mass is then extruded through a die orifice into an atmosphere of reduced pressure and temperature maintained below the boiling point (B.P.) to produce void-free extrudates and above its B.P. to produce puffed extrudates.
  • Aqueous coating compositions containing the low viscosity ethylenically unsaturated starch hydrolysates are particularly useful when it is desired to coat substrates at dry binder weight levels of at least 40%.
  • Substrates may be uniformly wetted and coated at solids levels ranging from about 50% to 75% by weight with stability against syneresis, separation and viscosity changes. Such coatings dry easily at nominal evaporation costs.
  • Depolymerisation of the starch to the appropriate short chain length (e.g. Dextrose Equivalent (D.E.) 0.2-100) for coating applications may be accomplished by conventional saccharification and/or thinning techniques (e.g.
  • the starch chains may be depolymerised to the appropriate chain length prior or after the ethylenically unsaturated derivatives are prepared: Starch chains having a degree of polymerisation comparable to that achieved by alpha-amylase hydrolysis of starch to a D.E. ranging from 0.1 to 32 (advantageously from 0.25 to 15 and most preferably less than 10) may be effectively used to coat substrates.
  • the reduced starch chain length will not adversely affect starch coating permanence provided the ethylenically unsaturated D.S. is sufficiently high enough to provide chains which contain multifunctional unsaturation sites.
  • the water content is typically adjusted to a fluidity most suitable to coat the substrate.
  • the starch coating composition viscosity may vary considerably and depends to a large extent upon the type of coating operation employed (e.g. from 0,001 to 40 Pa.S (1 to 40,000 cps) or higher for extrusion coating).
  • the proportions of water, monomer and ethylenic unsaturated starch weight ratios may likewise vary considerably (e.g., 5 to 10,000 parts by weight, i.e. pbw, water and 1 to 5,000 pbw monomer for each 100 pbw ethylenically unsaturated starch).
  • a homogeneous starch coating composition of viscosity greater than 10 cps (0.01 PaS) but less than 5,000 cps (5 PaS) (most typically from 20 cps to 1,000 cps-0.02 PaS to 1 PaS) and containing from 25 to 800 pbw water and 10 to 2,000 pbw ethylenically unsaturated monomer for each 100 pbw ethylenically unsaturated starch.
  • Water-miscible organo solvents or surfactants are desirably incorporated into the coating composition for purposes of achieving homogeneity and a uniform monomer dispersion if the starch coating formulation contains a low amount of water and a high monomer concentration.
  • Starch coating compositions which are adapted for use in high-speed coating operations are typically formulated at a viscosity ranging from 100 cps to 300 cps (0.1 PaS to 0.3 PaS) (with or without fugitive organo solvents or surfactants) at 30 to 500 pbw water and 25 to 1,000 pbw (preferably between 50 to 500 pbw) ethylenically unsaturated monomer for each 100 pbw ethylenically unsaturated starch.
  • starch coating homogeneity is more easily achieved by using less than 3 weight parts ethylenically unsaturated monomer for each 2 weight parts of water and preferably at a weight ratio of less than one part monomer for each water part.
  • the copolymerised ethylenically unsaturated starch consists essentially of an acrylamide starch having a D.S. ranging from 0.005 to 0.05 and a D.E. ranging from 0.25 to 15, and the copolymerisate contains 100 parts by weight copolymerised ethylenically unsaturated starch hydrolysate, from 100 to 750 parts copolymerised ethylenically unsaturated monomer which contains "W" groups and from 0 to 200 parts by weight of copolymerised ethylenically unsaturated monomers devoid of "W" groups.
  • the copolymerisates are copolymerised by conventional polymerisation initiating means.
  • the unpolymerised starch and monomers may be conveniently prefabricated into the desired configuration and then copolymerised in situ via such conventional polymerisation initiating systems.
  • the starch compositions will undergo copolymerisation upon exposure to conventional irradiation processes which generate in situ polymerisation initiators therein (e.g. electron-beam X-ray, alpha-ray, gamma-ray, etc. initiation).
  • free-radical catalysts or free-radical precursors may be uniformly incorporated into the unpolymerised starch composition which will then latently copolymerise upon exposure to appropriate initiating conditions (e.g. photochemical, ultra-violet, heating or microwave techniques, etc.).
  • Conventional free-radical polymerisation initiators at levels sufficient to copolymerise the ethylenic unsaturated starch and monomer (e.g. 0.2% to 20% on a starch-monomer weight basis) which may be incorporated into the starch composition include the organic and inorganic peroxides (e.g.
  • oxidation- reduction initiator systems ammonium, potassium or sodium persulphates or hydrogen peroxide with reducing agents such as sodium bisulphites, sulphites, sulphoxylates, thio-sulphates, hydrazine, etc.
  • azo initiators e.g.
  • tertiary aliphatic azo compounds which undergo homolytic dissociation such as azo di-isobutyronitrile, phenylazotriphenylmethane, 1,1'-azodicyciohexane-carbonitriie, 1,1 - dimethyl - azoethane; diazoamino compounds (e.g. 3,3-dimethyl-1-phenyl-triazene and aryldiazo thioethers) and other free-radical generating catalysts such as certain aromatic ketones (e.g. benzoin methyl ether, benzophenone and its derivatives), chlorinated aromatics as well as other free-radical type of polymerisation initiators.
  • aromatic ketones e.g. benzoin methyl ether, benzophenone and its derivatives
  • chlorinated aromatics as well as other free-radical type of polymerisation initiators.
  • Free-radical initiator systems which require externally applied energy (e.g. thermally, photochemical, etc.) for free-radical generation may be used to provide a latently copolymerised system.
  • the free-radical polymerisation initiators are uniformly dispersed throughout the aqueous phase of the starch composition at levels ranging from 0.3% to 10% (based on polymerisable starch and monomer dry weight).
  • Polymerisation initiation via U.V. and white light sources is particularly useful in high-speed coating operations.
  • white light sources e.g. 200-430 nanometer (nm) range, such as by carbon arc lamps, Xenon lamps, high pressure mercury lamps
  • conventional photosensitisers e.g. triethanol amine-soluble benzophenones, eosin-sulphonates, methylene blue-sulphinate, combinations thereof, etc.
  • active energy transfer may be incorporated into the starch composition to facilitate the copolymerisation initiation reaction.
  • the ultra-violet polymerisation initiating processes are generally suitable for coatings or films of a thickness of less than about 20 mils (preferably less than about 10 mils).
  • Thicker starch polymerisate articles or films normally require higher penetrating irradiation devices (e.g. X-ray, electron-beam, gamma generation, etc.) or thermal induction.
  • the ultra-violet copolymerisation process is particularly effective for high solids starch coating applications (e.g. 55% to 75% dry solids) because it simultaneously dries and copolymerises the starch coating in a single step.
  • Water-dispersible, non- fugitive free-radical initiating systems e.g. catalysts which evaporate or do not leave catalytic residue in the copolymerisate
  • hydrogen peroxide are preferred.
  • the water-absorbent starch copolymerisates have a wide and divergent field of use.
  • a major advantage of the water-absorbent starches of this invention resides in the ability to apply the unpolymerised product to a substrate or prefabricate it into the desired shape or configuration and then convert it to a water-absorbent, starch copolymerisate.
  • the unpolymerised product can be applied to divergent substrates ranging from natural and man-made products and thereafter polymerised in situ to form an integrated product of unitary construction. This advantage is particularly useful for applications wherein it is desirable to permanently affix or impregnate a natural or synthetic substrate (e.g.
  • water-absorbent starches include hygienic pads, bandages, surgical and catamenial tampons, sanitary napkins, diapers, antiperspirant and deodorant pads, sponges, surgical pads, sorptive dental rolls, disinfectants, decorative seedling films, etc.
  • the water-absorbent starch copolymerisates may be admixed with natural and man-made products for such divergent uses as cosmetics, water scavengers, paint removers, solid humectants, pesticides, improving the water-holding capacity of soils, catalysts or chemical carrier, binders, etc.
  • aqueous acrylamidomethyl starch hydrolysate (D.S. 0.009) was prepared employing the following proportions of reagents.
  • the ingredients were mixed and filtered on a Buchner funnel.
  • the starch cake was sucked free of excess aqueous phase and the unwashed cake (with 63 percent retention of non-starch reagents) was air-dried to a ten percent drying loss.
  • the dried reaction premix had the following ratios of reagents (pbw)-250 starch; 7.95 N-methylolacrylamide, 0.025 methyl hydroquinone; 29 water.
  • the powdered reaction premix was layered onto a stainless steel tray and heated for 2 hours in a forced air oven at 75.5°C.
  • the dried product contained 0.10 percent nitrogen (dry basis), which when corrected for the nitrogen in the STA-TAPE 100 starch (0.022 percent) is equivalent to a D.S. of 0.009. Further information on the preparation of the acrylamidomethyl starches may be found in German Offenlegungsschrift 27 18 210.
  • acrylamidomethyl starch (0.77 grams) was homogeneously dispersed into 8.43 grams water (15 minutes at its boiling point) and cooled to ambient temperature in a 50 ml flask.
  • Acrylic acid (0.48 grams) and acrylamide (0.24 grams) were homogeneously dispersed into the acrylamido starch solution followed by the addition of 0.0169 grams (d.s.b.) ammonium persulphate (2.28% aqueous solution) and 0.0076 gram (d.s.b.) of sodium bisulphite (1.04% aqueous solution). Then 0.002 gram (d.s.b.) of ferrous sulphate (0.28 wt.% FeS0 4 .
  • the dispersion (36.84 grams) was further diluted with 55.26 g distilled water to provide a 2% gel solids dispersion.
  • the viscosity of the dispersion respectively after standing for six and twenty-three hours was 0.5 Pa.S (500 cps) and 3.5 Pa.S (3500 cps).
  • the solids was again diluted with 90.52 g of distilled water (1% dry solids dispersion) which after 29 hours standing had a 0.7 Pa.S (700 cps) viscosity (No. 4 spindle at 20 rpm) and after 58 hours a viscosity of 0.71 Pa.S (710 cps).
  • the 1 % gel dispersion was ambiently air-dried (evaporating dish for 11 days).
  • a 0.1526 g sample of the resultant gummy resin was transferred and hydrate with 11.85 grams of distilled water in a 15 ml centrifuge tube. The sample swelled to the 12 ml. volume. The hydrated sample was centrifuged for 15 minutes at 10 3 g's. The supernatant liquid was decanted into a tared aluminum pan. 11.38 grams of the swollen gel was transferred to a 50 ml centrifuge tube and diluted with 11.38 grams of water and allowed to swell for 17 hours followed by centrifugation for 15 minutes at 10 3 g's. The supernatant (pH 6.6) along with the aforementioned supernatant was analysed for water-soluble starch (0.0423 grams or 27.7% by weight via evaporation).
  • the copolymerisate weight swelling ratio was determined by the equation wherein 1, 0 and S respectively represent the weight of swollen insolubles, 9.63 grams; original sample 0.1526 grams and solubles, 0.0423 grams (i.e.,
  • a cationic, water-absorbent starch copolymerisate was prepared by copolymerising (in 34.6 pbw distilled water) 8.5 pbw (0.008 moles) acrylamidomethyl starch (d.s. 0.008), 30.9 pbw (0.0199 moles) and 11.1 pbw acrylamide (0.0241 moles).
  • the copolymerisation reaction was exothermically initiated with 0.1 pbw ammonium persulphate (0.13(NH 4 ) 2 S 2 O 8 +5 pbw water), 0.07 pbw sodium bisulphite (0.07 pbw NaHS0 3 +5 pbw water) and 0.01 pbw FeSO 4 ⁇ 7H 2 O (0.01 pbw FeSO 4 . 7H z 0+4.7 pbw water).
  • the copolymerisation reaction was completed to yield a water-absorbent, hydrated copolymerisate gel. This cationic gel was analysed in accordance with the test procedure of Example I at 25°C.
  • the copolymerisate contained 73% (by weight) insoluble copolymerisate solids and 27% (by weight) solubles and had a 152 WSR.
  • the insoluble copolymerisate absorbed 152 times its dry weight of water at a pH 4.0 and 25°C.
  • a cationic water-absorbent starch copolymerisate was prepared by copolymerising 0.008 moles acrylamidomethyl starch (D.S. 0.008 at 8.45 pbw), 0.0243 moles acrylamide (11.25 pbw) and 0.01673 moles (30.82 pbw) with the exothermic initiating system of Example II.
  • the resultant copolymerisate gel (copolymerisation completed within 150 seconds after initiation) was admixed with 2000 mi. water and allowed to swell for 8 days at 25°C.
  • the decanted supernatent liquid portion thereof contained 20.18% water-solubles.
  • the insoluble copolymerisate (79.82% of the total copolymerisable reactants) absorbed 86 times it weight of water at pH 3.6 and 25°C.
  • This example illustrates a water-absorbent copolymerisable starch coating composition which may be copolymerised in situ to provide a substrate (e.g. textile, papers, etc.) coated with the water-absorbent starch copolymerisate.
  • the copolymerisable coating composition (pH 6.0) consisted of 10 pbw acrylamidomethyl starch (0.01 D.S.) 2 , 47 pbw distilled water, 12 pbw acrylic acid, 12 pbw acrylamide, 9 pbw potassium hydroxide and 10 pbw aqueous hydrogen peroxide (30%).
  • copolymerisable starch composition Five grams of the copolymerisable composition was placed in an aluminium weighing pan (2" or approx. 5 cm I.D.) and irradiated 2.54 cm (an inch) away from a 275 watt sun lamp for 1 minute to give a firm gel. Another portion of copolymerisable starch composition was applied with a No. 40 wire wound rod to a 4"x 12" (10 cmx30.5 cm) glass plate and irradiated 6 passes at 20 ft./min. (6.2 m/min) at 1.5" (3.8 cm) under a Hanovia 679A lamp (Hanovia is a Registered Trade Mark).
  • the copolymerisable starch composition gelled on the first pass (1/6 sec.) and converted to a dry film after the sixth pass through the irradiator (i.e. one second).
  • the WSR for the resultant starch copolymerisates were 150.
  • a 0.056 D.S. acrylamidomethyl starch was used instead of the 0.01 D.S. acrylamidomethyl starch to provide a copolymerisate with a WSR of 30.
  • copolymerisable starch coating compositions passing the coated cotton through the rolls of a Birch Brothers Padder, placing the coated cotton pieces on glass plates and then irradiating the three samples for 4, 6 and 8 passes.
  • the dry coating add-on was 46% by weight.
  • the water swelling ratios were 120 for 4 irradiation passes, 86 for 8 passes and slightly more than 100 for the cloth which was exposed to 6 passes.
  • glucose-containing monomers such as those ranging from a completely hydrolysed starch (e.g. dextrose) to an unhydrolysed starch.
  • the glucose-containing monomers which contain multi-functional ethylenically unsaturated groups provide the necessary structure for the porous lyophilic network.
  • the most appropriate D.S. level for a glucose-containing monomer will depend upon the number of glucose units present in its starch chain.
  • starch copolymerisates as described herein possess a porous structure, their lyophilic properties can be altered via the composition and character of unsaturated starches, monomers and lyophilic groups which are used in their preparation.
  • starch copolymerisates which may be tailor-made to absorb specific solvents, chemicals and/or water-immiscible liquids (e.g. oil) are now possible.
  • lyophilic and amphophilic starch copolymerisates may be obtained by starch copolymerisates which contain both polar water-soluble and hydrophobic, water-insoluble substituents.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Graft Or Block Polymers (AREA)
  • Polysaccharides And Polysaccharide Derivatives (AREA)
  • Macromonomer-Based Addition Polymer (AREA)
  • Polymerisation Methods In General (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
EP78300036A 1977-06-20 1978-06-13 Water-absorbent starch copolymerisates and method for their preparation. Expired EP0000247B1 (en)

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US05/808,482 US4115332A (en) 1976-04-27 1977-06-20 Water-absorbent starch copolymerizates
US808482 1977-06-20

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0405917A1 (en) * 1989-06-26 1991-01-02 Sequa Chemicals Inc. Starch polymer graft
US5055541A (en) * 1989-06-27 1991-10-08 Sequa Chemicals, Inc. Starch polymer graft composition and method of preparation
US6423775B1 (en) 1999-01-25 2002-07-23 WORLéE-CHEMIE GMBH Starch-based graft polymer, process for its preparation, and use thereof in printing inks and overprint varnishes
WO2004085481A1 (en) * 2003-03-26 2004-10-07 Le Groupe Lysac Inc. Starch networks as absorbent or superabsorbent materials and their preparation by extrusion

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5648923B2 (da) * 1972-01-20 1981-11-18
JPS5922376U (ja) * 1982-08-03 1984-02-10 日立造船株式会社 バルブ用部品
JPS59100145A (ja) * 1982-12-01 1984-06-09 Denki Kagaku Kogyo Kk 導電性組成物
JPS60190448A (ja) * 1984-03-12 1985-09-27 Toshiba Chem Corp 耐熱性摺動用成形材料
US20070219521A1 (en) * 2006-03-17 2007-09-20 The Procter & Gamble Company Absorbent article comprising a synthetic polymer derived from a renewable resource and methods of producing said article
JP5852690B2 (ja) * 2013-04-26 2016-02-03 株式会社神戸製鋼所 ホットスタンプ用合金化溶融亜鉛めっき鋼板
CN119683605A (zh) * 2024-12-19 2025-03-25 深圳为方能源科技有限公司 淀粉基硬炭及其制备方法、负极片、钠离子电池和涉电设备

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Publication number Priority date Publication date Assignee Title
JPS51125468A (en) * 1975-03-27 1976-11-01 Sanyo Chem Ind Ltd Method of preparing resins of high water absorbency
US4079025A (en) * 1976-04-27 1978-03-14 A. E. Staley Manufacturing Company Copolymerized starch composition

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Starch & its Derivatives, J.A.Radley, Chapman & Hall 1968, p. 384 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0405917A1 (en) * 1989-06-26 1991-01-02 Sequa Chemicals Inc. Starch polymer graft
US5055541A (en) * 1989-06-27 1991-10-08 Sequa Chemicals, Inc. Starch polymer graft composition and method of preparation
US6423775B1 (en) 1999-01-25 2002-07-23 WORLéE-CHEMIE GMBH Starch-based graft polymer, process for its preparation, and use thereof in printing inks and overprint varnishes
WO2004085481A1 (en) * 2003-03-26 2004-10-07 Le Groupe Lysac Inc. Starch networks as absorbent or superabsorbent materials and their preparation by extrusion

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ES470976A1 (es) 1979-10-01
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IT1105365B (it) 1985-10-28
IT7849921A0 (it) 1978-06-19
DK273378A (da) 1978-12-21
CA1090027A (en) 1980-11-18
DE2861984D1 (en) 1982-09-30
EP0000247A1 (en) 1979-01-10
MX6762E (es) 1986-06-27
NO782126L (no) 1978-12-21

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