Classifications

• • 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
  • C08F2/00—Processes of polymerisation
  • C08F2/46—Polymerisation initiated by wave energy or particle radiation
  • C08F2/54—Polymerisation initiated by wave energy or particle radiation by X-rays or electrons
• • 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
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/04—Acids; Metal salts or ammonium salts thereof
  • C08F220/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
  • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
  • A61L15/42—Use of materials characterised by their function or physical properties
  • A61L15/60—Liquid-swellable gel-forming materials, e.g. super-absorbents
• • 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
  • C08F2/00—Processes of polymerisation
  • C08F2/46—Polymerisation initiated by wave energy or particle radiation

Definitions

• U.S. Patent 4,062,817 discloses polymers of unsaturated copolymerizable carboxylic acids, at least one alkyl acrylate or methacrylate wherein the alkyl group has 10 to 30 carbon atoms and another alkyl acrylate or methacrylate wherein the alkyl group has 1 to 8 carbons. This composition alleviated many of the deficiencies of the earlier compositions. Further improvements in the hydrophilic properties were obtained by compositions disclosed in U.S. Patent 4,066,583.
• This patent discloses a composition
• a composition comprising (1) a copolymer of the type disclosed in the '817 patent, except that after copolymerization 30 to 90 percent of the carboxylic groups were neutralized with an alkali metal or ammonia and (2) an aliphatic glycol, a plasticizer which is important in facilitating extrusion of the polymer.
• a method for preparing an interpolymer from a mixture of monomers comprising 50 to 90 weight percent of acrylic acid, 60 to 100% of. the carboxylic groups of said acid having been neutralized prior to polymerization with an alkaline metal hydroxide, 2 to 20 weight percent of an alkyl acrylate or methacrylate wherein the alkyl group has 10 to 30 carbon atoms, 5 to 30 weight percent of an alkyl acrylate wherein the alkyl group has 1 to 9 carbon atoms by exposing said mixture to an electron beam source of sufficient intensity to cause said monomers to polymerize.
• the monomers can be polymerized in any desired form, including films and fibers which would be most useful for absorption of water and body fluids, such as urine or blood.
• This invention is directed to a method of producing interpolymers which have outstanding absorption and retention properties of water and ionic solutions such as urine or blood by the use of electron beam radiation. More specifically, the invention deals with a method of producing polymers from a monomer mixture comprising a) 50 to 90 weight percent of acrylic acid, 60 to 100 percent and most preferably 80 to 100 percent of the carboxylic groups having been neutralized with an alkali metal hydroxide or ammonia base prior to polymerization, b) 2 to 25 weight percent of a higher acrylic ester monomer of the formula and wherein R' is hydrogen, methyl or ethyl and R is an alkyl group of 10 to 30 carbon atoms, c) 5 to 30 weight percent of a lower acryiic ester monomer of the formula
• R" is a lower alkyl group having 1 to 8 carbon atoms, 0 to 50 percent of said lower acrylic ester being replaced by acrylic or methacrylic nitrile or amide; said method comprising subjecting said monomers to electron beam radiation of sufficient intensity to cause said monomers to polymerize.
• the higher acrylic ester monomers are those which have a long chain aliphatic group and may be represented by the formula
• R is an alkyl group having from 10 to 30 carbon atoms, preferably 10 to 18 carbon atoms and R' is hydrogen, methyl or ethyl group.
• Representative higher alkyl acrylic esters are decyl acrylate, isodecyl acrylate, lauryl acrylate, stearyl acrylate, behenyl acrylate and melissyl acrylate and the corresponding alkacrylates including methacrylates for example.
• Mixtures of two or three or more long chain acrylic esters may be successfully polymerized with one of the carboxylic monomers to provide useful thickening resins of this invention.
• Particularly useful are those acrylates and methacrylates where the alkyl group contains 10 to 18 carbon atoms present preferably in amounts of about 5 to 20 weight percent of the total monomers.
• Outstanding polymers have been made with 15 + 5 weight percent isodecyl methacrylate, 10 + 3 weight percent lauryl methacrylate, 7 + 3 weight percent stearyl methacrylate.
• the lower acrylic esters can be represented by the formula
• R is an alkyl, alkoxy, haloalkyl, cyanoalkyl, hydroxyalkyl and like groups having from 1 to 8 carbon atoms and R' is hydrogen, methyl or ethyl group.
• R' is hydrogen or methyl and R is alkyl, most preferably methyl, and the lower ester is present in the amount of from 5 to 20 and most preferably 7 to 17 weight percent.
• acrylates include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, methyl methacrylate, methyl ethacrylate, ethyl methacrylate, octyl acrylate, heptyl acrylate, octyl methacrylate, isopropyl methacrylate, 2-ethyl-hexyl acrylate, nonyl acrylate, hexyl acrylate, n-hexyl methacrylate, hydroxy ethyl methacrylate, dimethylamino ethylmethacrylate.
• ⁇ , ⁇ - olefinically unsaturated nitriles preferably the monoolefinically unsaturated nitriles having from 3 to 10 carbon atoms such as acrylonitxile, methacrylonitrile, ethacrylonitrile, chloroacrylonitrile, and the like. Most preferred nitriles are acrylonitriles and methacrylonitrile.
• Another useful class of additional monomers which may be incorporated in the interpolymers of this invention is monoethylenically unsaturated amides which have at least one hydrogen on the amide nitrogen and the olefinic unsaturation is alpha-beta to the carbonyl group.
• the preferred amides have the structure wherein R 3 is a member of the group consisting of hydrogen and an alkyl group having from 1 to 4 carbon atoms and R 4 is a member of the group consisting of hydrogen and an alkyl group having from 1 to 6 carbon atoms.
• amides include acrylamide, methacrylamide, N-methyl acrylamide, N-t-butyl acrylamide, N-cyclohexyl acrylamide, N-ethyl acrylamide and others. Of the amides most preferred are acrylamide and methacrylamide.
• acrylic amides include N-alkylol amides of ⁇ , ⁇ -olefinically unsaturated carboxylic acids including those having from 4 to 10 carbon atoms such as N- methylol acrylamide, N-ethanol acrylamide, N-propanol acrylamide, and the like.
• the preferred monomers of the N-alkylol amide type are the N-alkylol amides of ⁇ , ⁇ - monoolefinically unsaturated monocarboxylic acids and the most preferred is N-methylol acrylamide.
• N-alkoxymethyl acrylamides which have the structure
• R 5 is selected from the group consisting of hydrogen and methyl
• R 6 is an alkyl group having from 1 to 8 carbon atoms.
• acrylamide includes "methacrylamide” within its meaning.
• the preferred alkoxymethyl acrylamides are those wherein R 6 is an alkyl group containing from 2 to 5 carbon atoms, and especially useful is N-butoxymethyl acrylamide.
• the monomer mixtures are prepared as aqueous dispersions which eliminates the need for organic solvents. This avoids the pollution problems caused by the removal of organic solvents or the cost associated with the removal of the pollutants.
• the aqueous dispersions contain 0.01 to 5%, and preferably 0.1 to 1%, of a surface active agent such as an anionic, amphoteric, or nonionic dispersing agent or a mixture of dispersants.
• a surface active agent such as an anionic, amphoteric, or nonionic dispersing agent or a mixture of dispersants.
• useful anionic dispersing agents include alkali metal or ammonium salts of the sulfates of alcohols having from 8 to 18 carbon atoms such as sodium lauryl sulfate; ethanolamine lauryl sulfate, ethylamine lauryl sulfate; alkali metal and ammonium salts of sulfonated petroleum and paraffin oils; sodium salts of aromatic sulfonic acids such as dodecane-l-sulfonic acid and octadecane-l-sulfonic acid; aralkyl sulfonates such as sodium isopropyl benzene sulfonate, sodium dodecyl benzene sulfonate and sodium isobutyl naphthalene sulfonate; alkali metal and ammonium salts of sulfonated dicarboxylic acid esters such as sodium dioctyl sulfosuccinate, disodium
• Nonionic dispersants such as octyl- or nonylphenyl polyethoxyethanol as well as the PLURONIC and the TRITON dispersants may also be used. Also useful are amphoteric dispersants such as dicarboxylic coconut derivatives (MIRANOL). Further examples of useful dispersants are those disclosed beginning on page 102 in J. Van Alphen's "Rubber Chemicals", Elsevier Publishing Co., 1956.
• cross-linking agents are not required to obtain useful, highly absorbent compositions of this invention, it may be desirable to incorporate a cross linking agent since films prepared from compositions containing a cross-linking agent tend to have greater gel strength and an improved ability for the copolymers to swell under a confining pressure.
• Cross-linking agents may be used in the concentration of about 0 to about 15% by weight based on the total weight of the monomers, and preferably about 1 to about 10%.
• Other crosslinking monomers include for example, diallyl esters, dimethallyl ethers, allyl or methallyl acrylates and acrylamides, tetraallyl tin, tetravinyl silane, polyalkenyl methanes, diacrylates and dimethacrylates, divinyl compounds as divinyl benzene, polyallyl phosphate, diallyloxy compounds and phosphite esters and the like.
• Typical agents are allyl pentaerythritol, allyl sucrose, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, pentaerythritol triacrylate, tetramethylene dimethyacrylate, tetra methylene diacrylate, ethylene diacrylate, ethylene dimethacrylate, triethylene glycol dimethacrylate, triallyl cyanurate, triallyl isocyanurate, diallyl itaconate, polyethylene glycol acrylates and methacrylates and the like.
• polymers from the above discussed monomers are prepared by subjecting said monomers to electron beam radiation of sufficient intensity to cause said monomers to polymerize substantially completely.
• the amount and the intensity of radiation required will depend on the thickness of the film, the specific monomers employed, and the speed and the degree of polymerization desired. Generally, for the applications for which the resulting polymers are especially useful films, sheets or fibers in the range from 0.5 to 5 mils are most desirable. Therefore, relatively low intensity electron beam sources, generally less than 200 KV, would be sufficient to effect polymerization. Generally for the type of monomer systems employed in this invention from 1 to 15 M rads of radiation is required. However, it should be pointed out that the amount and intensity of radiation must be optimized for each system taking all variables into consideration, i.e., the monomers employed, the thickness of the film, the desired speed of polymerization, the desired degree of polymerization and the rate of radiation.
• the copolymers of this invention can be radiation polymerized in any form, the film form being the most practical one.
• the resulting film is an elastic, flexible material that has an appreciable degree of strength. If a fine, flaky form is desired, the film can be converted to such a form by drying and then pulverizing or grinding it in standard equipment.
• these polymers find many uses in film, fiber, fabric and similar forms. They are of particular utility in the disposable nonwoven industry where there is need for polymers which will absorb and retain water and ionic physiological fluids. An important feature of these polymers is their enhanced thickening property even in the presence of a salt. Specific applications include disposable diapers, medical-surgical supplies and personal care products. Such applications require a polymer which must imbibe the liquid to be absorbed rapidly and be a polymer that will not dissolve. Further, the fluid must be immobilized or congealed in some way to be retained.
• the materials may also be used as suitable additives to greatly increase the absorptive power of conventional absorbents such as cotton, wood pulp and other cellulosic absorbents used in applications such as wiping cloths, surgical sponges, catamenial devices, and the like.
• a disposable diaper there is an inner layer of a soft absorbent nonwoven material that absorbs and passes urine to an inner layer of fluffy fibrous absorbent material, wherein during the construction of this nonwoven fiber agglomerates or fibers of the polymers of this invention may be included and an additional impervious plastic later, as polyethylene.
• a film of the copolymers of this invention may be used between the outer plastic layer and the inner fluffy absorbent layer.
• the instant copolymers can also be used as flocculants in water treatment, in metallurgical processes, in ore beneficiation and flotation, in agricultural applications such as in soil treatment or seed coating or in any applications where the inherent properties of the polymer are desirable, such as its thickening property in an aqueous medium.
• the monomer mixture can be prepared by following one of two simple procedures. One method is to dissolve a previously prepared and dried alkali metal or ammonium acrylate in water to which is then added a dispersant. To the aqueous solution is then added a mixture of acrylate esters. Another method is to prepare the acrylate salt in situ by adding acrylic acid to the proper amount of cold aqueous base (e.g. KOH, NaOH or NH 4 OH) with cooling. To the aqueous solution is then added a mixture of the acrylate esters. The dispersant can be added at any time.
• a dispersant e.g. KOH, NaOH or NH 4 OH
• aqueous monomer dispersion is spread to a desired thickness (e.g. by the use of Boston-Bradley adjustable blade, by spraying or other known means) on a suitable substrate (e.g. Mylar, polyethylene, paper, etc.).
• a suitable substrate e.g. Mylar, polyethylene, paper, etc.
• This film can be dried in an oven at about 50oC for 1 to 15 min. After drying the film may still retain some flexibility or become brittle and flaky, depending on the length of drying.
• the monomer mixture was prepared following the above described procedure using the following components: 83 g. acrylic acid
• a test diaper is constructed from a 4 inch diameter pad (10.16 cm.) using materials from a commercial diaper.
• a film prepared from a polymer to be tested for absorbency is placed in the center of the test diaper between two layers of fluff (wood pulp).
• a diaper without the polymer film is used as a blank.
• the demand-wettability apparatus is a burette filled with the test fluid and firmly stoppered at the top, with an air bleed on the side, and a delivery orifice on the bottom connected by a flexible tube to the sample holder.
• the sample holder has an opening in the center which is connected to the flexible tube that leads to the delivery orifice. of the burette.
• the sample holder is level with the air bleed opening in the burette. With this closed-system arrangement the fluid in the flexible tube that comes up to the opening in the sample holder is at zero pressure.
• test diaper when the test diaper is placed on the sample holder over the opening it will absorb the fluid on its own through wicking action.
• the sample's own absorbent powder will determine the rate and amount of fluid that will be withdrawn from the burette. The amount of fluid withdrawn at any given time can be easily read from the burette calibration.
• absorbency can be measured against a range of pressures that can be obtained by placing various weights on top of the test diaper. Such pressures are intended to simulate the pressures applied on a diaper in actual use.

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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)
• Engineering & Computer Science (AREA)
• Hematology (AREA)
• Dispersion Chemistry (AREA)
• Materials Engineering (AREA)
• Epidemiology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Absorbent Articles And Supports Therefor (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Applications Claiming Priority (2)

Publications (2)

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• 1980
  • 1980-08-18 WO PCT/US1980/001068 patent/WO1981000714A1/en not_active Application Discontinuation
  • 1980-08-18 BR BR8008821A patent/BR8008821A/pt unknown
  • 1980-08-18 JP JP50210380A patent/JPS56501091A/ja active Pending
  • 1980-09-01 GR GR62779A patent/GR70006B/el unknown
  • 1980-09-09 IT IT24562/80A patent/IT1132723B/it active
  • 1980-09-09 BE BE0/202047A patent/BE885157A/fr unknown
  • 1980-09-09 KR KR1019800003555A patent/KR840000370B1/ko active
  • 1980-09-11 ES ES494976A patent/ES494976A0/es active Granted
• 1981
  • 1981-03-23 EP EP80901781A patent/EP0035538A1/de not_active Withdrawn
  • 1981-05-08 DK DK206081A patent/DK206081A/da not_active Application Discontinuation

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