EP1202797A1 - Alliage polymere/argile en reseau - Google Patents

Alliage polymere/argile en reseau

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Publication number
EP1202797A1
EP1202797A1 EP00930911A EP00930911A EP1202797A1 EP 1202797 A1 EP1202797 A1 EP 1202797A1 EP 00930911 A EP00930911 A EP 00930911A EP 00930911 A EP00930911 A EP 00930911A EP 1202797 A1 EP1202797 A1 EP 1202797A1
Authority
EP
European Patent Office
Prior art keywords
clay
alloy
monomer
polymer
group
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP00930911A
Other languages
German (de)
English (en)
Inventor
John Payzant
Zhihong Zhou
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Alberta Research Council
Original Assignee
Alberta Research Council
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Filing date
Publication date
Application filed by Alberta Research Council filed Critical Alberta Research Council
Publication of EP1202797A1 publication Critical patent/EP1202797A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D31/00—Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution
    • E02D31/002—Ground foundation measures for protecting the soil or subsoil water, e.g. preventing or counteracting oil pollution
    • E02D31/004—Sealing liners
    • 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
    • A61L15/18—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons containing inorganic materials
    • 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
    • A61L15/22—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons containing macromolecular materials
    • A61L15/24—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/12—Naturally occurring clays or bleaching earth
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
    • B01J20/26—Synthetic macromolecular compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D19/00—Keeping dry foundation sites or other areas in the ground
    • E02D19/06—Restraining of underground water
    • E02D19/12—Restraining of underground water by damming or interrupting the passage of underground water
    • E02D19/18—Restraining of underground water by damming or interrupting the passage of underground water by making use of sealing aprons, e.g. diaphragms made from bituminous or clay material
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2300/00—Materials
    • E02D2300/0004—Synthetics
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2300/00—Materials
    • E02D2300/0037—Clays
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2300/00—Materials
    • E02D2300/0085—Geotextiles
    • E02D2300/009—Geotextiles with multi-layer structure
    • E02D2300/0092—Geotextiles with multi-layer structure including a liquid tight layer
    • E02D2300/0093—Geotextiles with multi-layer structure including a liquid tight layer including bentonite

Definitions

  • the present invention relates to an absorbent polymer and a process for making an absorbent polymer More specifically, the present invention relates to a networked polymer/clay alloy useful for example, without limitation, in containment applications as landfill liners or covers, reservoir liners, underground storage tank liners, secondary containment liners, and man-made bodies of water, or personal care absorbent articles, including diapers, training pants, feminine hygiene products such as sanitary napkins, incontinence devices and the like
  • SAPs Super absorbent polymers
  • SAPs are produced from a variety of components by a variety of processes
  • SAPs are often made from monomers such as acrylamide, acrylic acid and acrylate, which are particularly suitable for application in hygiene products
  • US 4,032,701 (Hughes, June 28, 1977) describes a process for producing polyacrylamide in dry and solid form using a polymerization catalyst selected from a group consisting of an alkali metal and ammonium sulfite, bisulfite and persulfate
  • a polymerization catalyst selected from a group consisting of an alkali metal and ammonium sulfite, bisulfite and persulfate
  • US 4,178,221 (Boutin et al, December 11 , 1979) describes a process for producing water-soluble acrylic polymers using a sequential photopolymenzation technique Photopolymenzation promoters are incorporated in the monomer solution to facilitate polymerization
  • US 4,283,517 Perricone et al, August 11 , 1981
  • US 4,295,987 (Parks, October 20, 1981 ) uses two cross-linking agents to produce a cross-linked sodium polyacrylate absorbent
  • Further examples of the production of SAPs providing improved properties are provided by US
  • the SAP produced by each of the above-noted patents is manufactured from a chemical monomer to produce a synthetic polymer
  • chemical monomers tend to be relatively expensive and therefore, the use of the SAP produced therefrom tends to be limited to applications requiring a relatively small amount of SAP
  • SAP made from chemical monomers tends to be too expensive for use in environmental applications given the large volumes that are typically required
  • the most significant expense in producing SAP is the cost of the chemical monomer
  • these synthetic polymers may be subject to chemical, electromagnetic (radiation) and biological (bacterial) degradation when placed in the surface environment
  • swelling clays may be used to provide water-absorbency to a product With respect to cost, the cost of swelling clays tends to be minimal compared to that of the chemical monomers described above In addition, swelling clays are relatively stable compared to chemical monomers and are not as subject to degradation However, swelling clays have a water absorption capacity significantly less than that of SAP
  • the polymers may be physically mixed into swelling clays to form a composite
  • the monomers may be intercalated in the swelling clays and polymerized into a nanocomposite
  • the incorporation of the swelling clays into the SAP reduces the total cost of the SAP and enhances its resistance to chemical, electromagnetic and biological degradation, while still providing an improved water absorption capacity as compared to that of the swelling clays alone
  • US 4,418,163 (Murakami et al, November 29, 1983) describes a method of making a water absorbing composite that is comprised of an inorganic powder and an absorbent resin covering the surfaces of the individual particles of the inorganic powder
  • the inorganic powder is white carbon, synthetic silicate white carbon, basic magnesium carbonate, ultrafine magnesium silicate, light and heavy calcium carbonate, soft and hard clay, talc, vermiculite, pearlite, barium sulfate (baryte) or mica
  • this patent describes a process for coating an inorganic powder with a polymer Similar processes are described in US 4,889,885 (Usuki et al, December 26, 1989) and US 5,352,287 (Wason et al, October 4, 1994)
  • Chinese Patent No 85-1 -02156-A (January 14, 1987) describes a method of preparing a bentonite-acrylamide based SAP using cobalt-60 ⁇ -ray irradiation Specifically, the Chinese patent uses ⁇ -ray irradiation to initialize polymerization As well, Nagae H et al (Kobunshi Ronbun 47 8 631-638, 1990) describes the preparation of complex composite films by adding acrylamide and water to montmo ⁇ llonite and polymerizing the product using ⁇ -ray irradiation Thus, as with Blumstein, each of these processes requires an irradiation source for polymerization
  • Ogawa M et al (Clay Science 7 243-251 , 1989) describes the preparation of montmo ⁇ llonite-polyacrylamide intercalation compounds by polymerizing the intercalated acrylamide monomers in the interlayer region of the montmo ⁇ llonite using a free radical initiator The polymerization is performed using a relatively complex process involving the use of an organic solvent, namely n-heptane First, the montmo ⁇ llonite is intercalated into an acrylamide aqueous solution The product is then dried and washed with an organic solvent, namely CCI 4 or n-heptane, to remove excess acrylamide Finally, the intercalated acrylamide is polymerized by heating the intercalation compounds with benzoyl peroxide as an initiator in n-heptane
  • Kato, C et al (Clays and Clay Minerals 29 4 294-298, 1981 ) describes the polymerization of intercalation compounds of styrene and ammonium montmo ⁇ llonite Specifically, clay suspensions, namely montmo ⁇ llonite, are mixed with ammonium solutions After washing and drying the resulting product, the dried organoammonium-montmonllonites are immersed in styrene monomer The resulting stearyltrimethylammonium-montmorillonite is dried and polymerized using benzoyl peroxide as an initiator
  • a process for producing a networked polymer/clay alloy comprising the steps of (a) preparing a monomer/clay mixture by mixing at least a monomer, clay particles, a cross-linking agent, and a mixing fluid in a vessel, (b) exposing the monomer/clay mixture to a polymerization initiator means, and (c) polymerizing the monomer/clay mixture so that a networked polymer/clay alloy is formed
  • a networked polymer/clay alloy comprising a chemically integrated composition of polymer and clay, so that, when the alloy is immersed in deionized water, at a temperature in a range of from about 20°C to about 30°C, the alloy swells with substantially no clay separating from the alloy
  • Fig 1 is a scanning electron microscope (SEM) micrograph of a top plan perspective of the reinforcing agent used in Example 3, at a magnification of 140X
  • Fig 2 is an SEM micrograph of a hydrated polymer used for comparison in Example 3, at a magnification of 7000X
  • Fig 3 is an SEM micrograph of a cross-section of a reinforced networked polymer/clay alloy composite produced in Example 3, at a magnification of 50X
  • Fig 4 is an SEM micrograph of a cross-section of a reinforced networked polymer/clay alloy composite produced in Example 3, at a magnification of 270X
  • Fig 5 is an SEM micrograph of a cross-section of a water-swelled reinforced networked polymer/clay alloy composite produced in Example 3, at a magnification of 500X,
  • Fig 6 is an SEM micrograph of a cross-section of a water-swelled reinforced networked polymer/clay alloy composite produced in Example 3, at a magnification of 4500X,
  • Fig 7 is an SEM micrograph of a cross-section of a water-swelled polymer, without clay, at a magnification of 650X,
  • Figs 8A and 8B are drawings based on photographs taken of Sample A in Example 4 prior to immersion (8A) and after 3 hours immersion in deionized water (8B)
  • Figs 9A and 9B are drawings based on photographs taken of Sample B in Example 4 prior to immersion (A) and after 3 hours immersion in deionized water (9B)
  • Figs 8A and 8B are drawings based on photographs taken of Sample A in Example 4 prior to immersion (8A) and after 3 hours immersion in deionized water (9B)
  • Figs 10A and 10B are drawings based on photographs taken of Sample E in Example 4 prior to immersion (10A) and after 3 hours immersion in deionized water (10B)
  • “Monomer” is an organic molecule that can combine with a number of the same or different molecules to form a large molecule having repeating monomeric units, wherein the repeating monomeric units have a similar chemical architecture and atom composition as the monomeric units
  • “Polymer” is a large molecule built from the same or different repeating monomeric units and typically has a molecular weight in a range from about 10,000 to about 20,000,000 Polymer, as used herein, also includes any polymer made from two or more different repeating units, such as copolymers (i e , comprising two different monomeric units), terpolymers (i e , comprising three different monomeric units), tetrapolymers (i e , comprising four different monomeric units) and so on Moreover, the repeating monomeric units can alternate in a sequential pattern (e g , A — B — A — B), block pattern (e g , A — A — B — B), random pattern (A — B — B —
  • “O gomer” is also built from the same or different repeating monomer units but is a smaller molecule than a polymer and typically has a molecular weight in a range of from about 200 up to about 9,000
  • "Polymerization Initiator Means” is a chemical substance, gamma ray irradiation, X-ray irradiation, irradiation by high energy sub-atomic particles, each type of radiation having a wavelength less than about 10 nm, (collectively, high energy irradiation) and combinations thereof that can increase the reactivity of a monomer so that a polymerization or oligome ⁇ zation chain reaction between monomers is initiated and a polymer or ohgomer is formed
  • certain chemical substances become either an ionic or free radical species that can react with a monomer alone to produce an ionic or free radical monomeric species, which can, in turn, react with another monomer, thereby initiating a polymerization reaction
  • high energy irradiation can
  • Networked Polymer is a very large polymer molecule formed by cross-linking multiple oligomers and/or polymers to form an interconnected polymeric network
  • a networked polymer can have cross-linking moieties between oligomers and/or polymers, where the moieties are formed from either the cross-linking agent itself, branches attached to the backbone of each ohgomer and/or polymer or combinations thereof
  • NPC Alloy is a chemically integrated composition of polymer and clay Clay particles form a unique chemical association with the networked polymer as it is formed
  • the chemical association may be, for example, without limitation, through hydrogen bonding, ionic bonding, Van der Waal's/dipole bonding, affinity bonding, covalent bonding and combinations thereof
  • An NPC alloy of the present invention is an absorbent material useful, for example, without limitation, for making fluid barriers, such as landfill liners or covers, reservoir liners, underground storage tank liners, secondary containment liners, and liners for man-made bodies of water, or personal care absorbent articles, including diapers, training pants, feminine hygiene products such as sanitary napkins, incontinence devices and the like
  • the alloy preferably absorbs water to form a barrier, which then has a relatively low permeability to water, oil and other liquids
  • the alloy preferably has a high water absorbency capacity
  • the properties of the NPC alloy can be adjusted depending on the application
  • the NPC alloy of the present invention has improved resistance to chemical, electromagnetic radiation and biological degradation in surface and subsurface conditions
  • improved resistance to chemical degradation we mean that the alloy has improved resistance to, for example, without limitation, salt water and drainage fluids with high heavy metal content and/or acidic pH
  • improved resistance to electromagnetic degradation we mean that the composite has an improved resistance to ultraviolet (UV) and other potentially detrimental electromagnetic radiation
  • UV ultraviolet
  • improved resistance to biological degradation we mean that the NPC alloy would be more resistant to bacterial attack after installation, as compared with a polymer without clay
  • a liner produced with the NPC alloy represents an improvement over a conventional geosynthetic cla"y liner ("GCL”), which typically loses its effectiveness on exposure to salt water
  • polyacrylamide is stable at surface and sub-surface conditions However, it is susceptible to chemical and UV degradation
  • the clay reduces degradation in the NPC alloy by protecting the polymer
  • the NPC alloy is more resistant to biological degradation than, for example, polyacrylic acid alone
  • the NPC alloy When used in barrier applications, the NPC alloy weighs less than a comparably effective clay loading for a conventional GCL per unit area Also, a liner produced with the NPC alloy can be used without pre-hydration, as is often required for conventional GCL's
  • An NPC alloy is produced by mixing a monomer, clay particles, a cross-linking agent and a mixing fluid The monomer/clay mixture is exposed to an initiator means to initiate polymerization to form a networked polymer/clay alloy
  • the polymer and clay in the NPC alloy cooperate physically and chemically (i e , physicochemically) to contribute to the alloy's water absorbency
  • the alloy can swell while only negligible amounts of clay, if any, (i e , substantially no clay) separate from the composite when it is immersed in deionized water at temperatures in a range of from about 1 °C to about 60°C
  • the monomer/clay mixture used in making the NPC alloy includes, without limitation, a monomer, clay particles, a cross-linking agent and a mixing fluid
  • a monomer e.g., a monomer, clay particles, a cross-linking agent and a mixing fluid
  • MCX mixing fluid
  • the monomer is at least partially soluble in the mixing fluid
  • a monomer soluble in the mixing fluid may be mixed with other monomers that are soluble or insoluble in the mixing fluid
  • at least one water-soluble monomer has the following general formula
  • a monomer that can be co-polymerized with a monomer of the above general formula are vinyl esters, such as vinyl acetate Vinyl acetate is readily co-polymerized and may be retained as a vinyl acetate moiety or subsequently hydrolyzed to the corresponding vinyl alcohol
  • the clay particles may be swelling or non-swelling clays Suitable swelling clay particles include, without limitation, montmo ⁇ llonite, saponite, nontronite, laponite, beidelhte, iron-saponite, hectonte, sauconite, stevensite, vermiculite, and combinations thereof
  • Suitable non-swelling clay particles include, without limitation, kaolin minerals (including kaolinite, dickite and nac ⁇ te), serpentine minerals, mica minerals (including ilhte), chlorite minerals, sepiolite, palygorskite, bauxite, silica and combinations thereof
  • the clay is a swelling clay such as, for example, smectite and vermiculite type clays More preferably, the clay is a smectite type clay
  • suitable smectites are, without limitation, montmonllonite (sometimes referred to as bentonite), beidelhte, nontronite, hectonte, saponite, sauconite and laponite
  • Bentonite is an example of a naturally-occurring combination of clay particles Bentonite is a rock rich in montmonllonite and may also comprise other smectites as well as other non- clay mineral constituents Consequently, montmo ⁇ llonites or their mixtures with other smectites are often referred to simply as bentonite
  • Bentonite clays are fine crystals or particles, usually plate-like in shape, with a lateral dimension up to 2 ⁇ m and a thickness in a range of a few to tens of nanometers (nm)
  • Swelling clays have the ability to absorb water and are less expensive than monomer Accordingly, the reinforced networked polymer composite of the present invention is less expensive than one produced without clay Moreover, clay particles are resistant to degradation in long-term environmental applications, while still providing water absorbency for long periods of time Non-swelling clays would provide increased resistance to salt water for the NPC alloy Also, non-swelling clays, like swelling clays, are less expensive than monomer and would reduce an application's cost
  • the weight ratio of clay to monomer in the MCX mixture is in a range of from about 0 05 1 to about 19 1 More preferably, the weight ratio of clay to monomer in the MCX mixture is in a range of from about 0 5 1 to about 3 1
  • Suitable chemical substances for use as cross-linking agents include, without limitation, N,N'- methylene bisacrylamide, phenol formaldehyde, terephthalaldehyde, allylmethacrylate, diethyleneglycol diacrylate, ethoxylated t ⁇ methylolpropane t ⁇ acrylate, ethylene carbonate, ethylene glycol diglycidal ether, tetraallyloxyethane, triallylamine, t ⁇ methylolpropanetriacrylate, and combinations thereof
  • WAC networked polymer's water absorption capacity
  • the weight ratio of the cross-linking agent to the monomer is preferably in a range of from about 0 05 100 to about 1 5 100 More preferably, the weight ratio of the cross-linking agent to the monomer is
  • the mixing fluid is a polar solvent
  • suitable mixing fluids include, without limitation, water, alcohol, oxygen-containing organic solvents, and combinations thereof, in which the monomer can be at least partially dissolved
  • suitable oxygen-containing organic solvents include, without limitation, alcohols, glycols, polyols, sulfoxides, sulfones, ketones and combinations thereof
  • the mixing fluid is water, alcohol or a combination thereof
  • the mixing fluid is water
  • the amount of mixing fluid in the MCX mixture is in a range of from about 30% to about 90% by weight More preferably, the amount of mixing fluid in the MCX mixture is in a range of from about 40% to about 80% by weight Most preferably, the amount of mixing fluid in the MCX mixture is in a range of from about 40% to about 60% by weight
  • the MCX mixture preferably comprises one or more additives Buffering agents and/or neutralizing agents may be used as additives to maintain the pH of the mixture in a predetermined range and/or neutralize acidic and/or basic monomers
  • metal complexing agents may be used as additives to form metal complexes, thereby sequestering metal ions that might otherwise interfere with forming the NPC alloy
  • acrylamide monomer is typically manufactured with cup ⁇ c salts as a stabilizer (e g , to inhibit polymerization during shipment or in storage)
  • a metal complexing agent such as a sodium carbonate or ethylenediaminetetracetic acid (EDTA)
  • EDTA ethylenediaminetetracetic acid
  • some additives can be used to satisfy multiple functions
  • sodium carbonate (Na 2 C0 3 ) and sodium bicarbonate (NaHC0 3 ) could function as both a buffering agent (i e , maintaining pH) and a neutralizing agent (i e , neutralizing acidic monomers), while also working as a metal complexing agent Therefore, it will be apparent to those skilled in the art that one or more additives can be used for forming an NPC alloy depending on the mono
  • buffering agents and/or neutralizing agents include, without limitation, sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, oxylate-containing compounds, sulfate-containing compounds, phosphate-containing compounds, and combinations thereof
  • metal complexing agents include, without limitation, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ethylenediaminetetraacetic acid (EDTA), EDTA salts, orthophosphate, pyrophosphate, metaphosphate, hydrogen phosphate, and combinations thereof
  • each of the components of the MCX mixture may be added in any order Preferably, however, the mixing fluid and monomer are mixed with any other desired component, followed by adding a chemical initiator and then adding the clay Also, caution should be exercised in mixing any mixture components to avoid any significant exotherms Otherwise, any significant exotherm should be allowed to cool A large exotherm from mixing components might otherwise lead to premature polymerization " shortly after the initiator is added, but before the mixture is heated under a controlled condition
  • the MCX mixture forms a slurry type mixture, which should be mixed until it is substantially homogeneous
  • NPC alloy is produced by polymerization of the MCX mixture while the cross-linking agent, acting in concert with the polymerization process, helps to form a networked polymer/clay alloy structure
  • Polymerization of the MCX mixture is initiated by a polymerization initiator means for generating an ionic or free radical monomeric species Initiation may be accomplished by adding a suitable chemical substance to the MCX mixture
  • electromagnetic radiation having a wavelength of 10 nanometers (nm) or less may be used alone or in combination with a chemical initiator
  • Suitable chemical substances for initiating polymerization include, without limitation, free radical initiators, carbanions, carbonium ions, and combinations thereof
  • free radical initiators include, without limitation, thermal initiators, and redox systems, which are typically two or more chemicals, which are added simultaneously as different solutions
  • thermal initiators include, without limitation, (1 ) alkali metal salts of sulfite, bisulfite, persulfate, benzoyl peroxide, and combinations thereof, (2) ammonium salts of sulfite, bisulfite, persulfate, benzoyl peroxide, and combinations thereof, (3) 2,2'-azob ⁇ s(2-am ⁇ d ⁇ no-propane)- dihydrochlonde, (4) 2,2'-azob ⁇ s(4-cyanopentano ⁇ c acid), and combinations thereof
  • the desired polymerization temperature for forming an NPC alloy composite is primarily dependent on the type and concentration of initiator means selected For example, lower polymerization temperatures may be used where a thermal initiator prone to forming free radicals at a lower temperature (e g , about 40°C to about 50°C) is used
  • the reaction is preferably at a temperature in a range of from about 40°C to about 95°C More preferably, however, the reaction temperature is at a temperature in a range of from about 60°C to about 85°C and most preferably, in a range of from about 65°C to about 80°C
  • a high energy radiation source such as gamma ray radiation
  • the polymerization reaction may be conducted as low as about ambient temperature, for example about 20°C
  • the polymerization reaction time is also primarily dependent on the type of initiator means used and its concentration However, other factors affecting the desired reaction time include the type of monomer and its concentration, and the depth of the MCX mixture.
  • a polymerization reaction typically, it will not terminate in response to a sharp temperature drop For example, once the MCX mixture is exposed to the desired initiation temperature, the polymerization reaction will proceed for some time thereafter, depending on the reaction temperature selected and the time period that the MCX mixture is exposed to the selected temperature (i e , heat exposure period)
  • higher initiator concentrations generally produce residual monomer concentrations of about 200 ppm or less However, these higher initiator concentrations are more likely to promote premature polymerization unless the temperature is kept sufficiently below 40°C
  • the time period that the MCX mixture is exposed to the selected reaction temperature may be in a range from as low as about 1 minute to as high as about 24 hours
  • potassium persulfate is used as a thermal initiator and the selected temperature is about
  • the duration of the heat exposure period is preferably in a range of from about 2 minutes to about 60 minutes More preferably, under similar conditions, the heat exposure period is in a range of from about 2 minutes to 45 minutes and, most preferably, in a range from about 3 minutes to about 30 minutes
  • redox systems include, without limitation, persulfate/bisulfite, persulfate/thiosulfate, persulfate/ascorbate, hydrogen peroxide/ascorbate couples, and combinations thereof
  • additional heat is not required when using a redox systems initiator because the reactions are often exothermic, so such systems can work effectively at temperatures in a range of from about the freezing point of the MCX mixture to the boiling point of the mixing fluid Typically, the temperature is ambient, about 20°C
  • polymerization may be initiated by electromagnetic radiation having a wavelength below about 10 nm such as, for example, without limitation, by gamma rays, X-rays, or high energy sub-atomic particles
  • electromagnetic radiation having a wavelength below about 10 nm
  • the polymerization reaction is typically conducted at ambient temperatures
  • the temperature can be higher or lower
  • UV radiation with wavelengths ranging from about 200 nm to 390 nm is not suitable for polymerization initiation of the MCX mixture because the clay will interfere with UV light's ability to penetrate into the sample, and thereby initiate the polymerization reaction, even with a photo-initiator present More specifically, it is believed that the clay preferentially absorbs the UV light, thereby inhibiting the UV light's effectiveness as an initiator means
  • all or a portion of the mixing fluid remaining in the NPC alloy product may be removed, for example by desiccating at room temperature or oven-drying If oven- dried, the composite should be dried at a temperature that does not adversely affect the properties or characteristics of the product, for example, at a temperature less than about 110°C
  • the moisture content of the products made with an NPC alloy is dependent on the application and other factors For example, a higher moisture content product provides greater flexibility and a lower initial permeability But a lower moisture content product can have reduced transportation costs Consequently, the desired moisture content will be determined by the environment in which the product will be used and maximum acceptable transportation costs
  • the moisture content is preferably in a range of from about 25% to about 75% by weight NPC Alloy
  • the NPC alloy swells on contact with water as the alloy absorbs water
  • the composite swells substantially as an integrated unit while only negligible amounts of clay, if any (i e , substantially no clay), separate from the composite when it is immersed in water at a temperature in a range of from about 1 °C to about 60°C, whether the water is saline or not
  • the degree to which the NPC alloy is networked will affect the alloy's capacity to absorb water
  • the NPC alloy may become water soluble under certain conditions and the clay could then substantially separate from the alloy
  • the NPC alloy may be so inflexible that it is unable to absorb sufficient amounts water and thereby reach either the desired fluid permeability and/or water absorption performance
  • a barrier made using the NPC alloy is often under a confining stress due to overburden
  • the flux (i e , the rate water travels at the specified pressure) of the composite is about 10 8 m 3 /m 2 /s or less, as measured by ASTM 5887-95
  • ASTM 5887-95 As the confining stress increases with additional overburden, the hydraulic conductivity of the barrier will decrease because the barrier will become compressed
  • Control and MCX mixtures were left in an oven overnight at 65°C for polymerization After polymerization, the Control and NPC alloys were transferred to glass dishes and dried at 105°C for 48 hours.
  • a projected WAC, WAC pr] , based on the Control WAC and clay content was also calculated according to the following equation.
  • the monomer WAC (WAC m ) was also calculated to determine the water absorption capacity based on the amount of monomer used to produce the polymer/clay alloy sample being tested
  • the WAC m was calculated according to the following equation- (H 2 0 Swollen NPC Alloy Mass - Dried NPC Alloy Mass)
  • the WAC for NPC alloy Samples 1 and 2 is 339 and 332, respectively This means that the NPC alloy absorbs 339 and 332 times its own weight in water for these two samples, respectively, versus a 352 WAC for the clay-free Control Bentonite clay typically has a paste-like consistency up to a water absorption of 5 to 10 times its weight, after which the clay becomes dispersed in water to form a slurry Consequently, because bentonite clay is not known as being highly water-absorbent on a per unit mass basis, as compared with a water-absorbent polymer, the drop in WAC shown in Table 2 with increasing clay to monomer ratio was a surprising and unexpected result For example, at a 1 1 ratio, those skilled in the art might have projected a WAC of just slightly more than 0 5 x the Control's WAC because only half of the NPC alloy is networked polymer So, taking into account the water absorption for clay alone (i e , about 5-10), a 1 1 clay
  • the WAC m of the polymer/clay alloys Samples 1-5 is similar to that of the Control sample As mentioned above, monomers are more costly than clay Thus, the WAC m results demonstrate the economic advantages of the NPC alloy
  • Table 2 demonstrates that good WAC results were obtained for the composition described in Table 1 in a clay to monomer ratio of about 0 3 to about 3 0
  • the optimal clay to monomer ratio will depend on the intended use of the compositions falling within the scope of the claimed invention For instance, beyond adjusting the clay to monomer ratio, as discussed more fully under Example 2, the cross-linking agent to monomer ratio can also be adjusted to increase or decrease the WAC to the desired level
  • a WAC for the NPC alloy when used for making a landfill liner, a WAC for the NPC alloy only needs to be high enough to ensure that the NPC alloy swells sufficiently to occupy any interstitial spaces that were not occupied by NPC alloy when the liner was formed This degree of swelling will ensure that the liner has sufficiently low permeability to water and other fluids
  • the WAC for an NPC alloy used in a landfill liner could be as low as about 5
  • a higher WAC up to about 500 could also be used in a landfill liner
  • a WAC significantly much higher than 50 could reduce the structural integrity of the alloy due to excess water
  • the above data illustrates that the unique polymer/clay alloy can provide effective water absorption
  • the clay component in the NPC alloy provides a cost effective means to make an NPC alloy while delivering the water absorbing and/or permeability property performance desired for the intended use
  • the cross-linking agent to monomer weight ratios ranged from 1 10 x 10 3 to 9 41 x 10 3 in the three MCX mixtures
  • the clay to monomer weight ratio was held constant at about 1 1
  • the clay used in the MCX mixtures was NATURAL GELTM
  • the monomer was a 1 4 (wt) mixture of acrylic acid (Ald ⁇ ch) and acrylamide (Cytec)
  • the MCX mixtures were left in an oven overnight at 65°C for polymerization After polymerization, the NPC alloys were transferred to glass dishes and dried at 105°C for 48 hours
  • the monomer WAC (WAC m ) was also calculated to determine the water absorption capacity based on the amount of monomer used to produce the NPC alloy sample being tested.
  • the NPC alloy's WAC increases as the cross-linking agent to monomer ratio decreases from 9 41 x 10 3 to 3 03 x 10 3
  • a further significant decrease in cross-linking agent to monomer ratio e g , to about 0 10 x
  • An MCX mixture was prepared as shown in Table 5
  • the clay used in the MCX mixture was NATURAL GELTM
  • the monomer was a 1 4 (wt) mixture of acrylic acid (Aldrich) and acrylamide (Cytec)
  • TERRAFIX ® 270R-A geotextile (Terrafix Geosynthetics Inc , Toronto, Ontario, Canada), as a reinforcing agent
  • a polyethylene cover sheet was placed on top of the MCX mixture and a vacuum pressure in a range of from about 16 to about 30 kPa was applied to the sample from the geotextile's opposing/side
  • the MCX mixture was intimately distributed in and on the geotextile material by applying the vacuum
  • the reinforced MCX mixture sample was put under an infrared heater at 80°C for 8 minutes for polymerization to form a reinforced NPC alloy composite
  • the moisture content of the reinforced NPC alloy composite was about 75%
  • the reinforced NPC alloy composite was examined using a JEOL Model No JSM 6301 FXV Scanning Electron Microscope (SEM, Japan Electron Optics Limited, Japan) at the SEM Facility, Department of Earth & Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada Samples were pretreated for SEM examination by placing the samples in a holder and immersing them in liquid nitrogen (i e , about -196°C) Once frozen, the samples were removed from the liquid nitrogen, using pliers or a knife, quickly torn or cut, as indicated below, to obtain a cross- sectional perspective of the sample The samples were then quickly transferred to the SEM vacuum chamber, where they were warmed to -40°C to sublime any surface ice crystals Next, the samples were placed in a coating chamber where a thin layer of gold was applied to the sample to increase electrical conductivity The samples were then returned to the SEM vacuum chamber for examination The samples were maintained at or near liquid nitrogen temperature during the gold coating and subsequent SEM examination This was done so that the structure of the sample
  • the SEM micrographs illustrate that (1 ) clay in the NPC alloy is chemically associated with the polymer, (2) clay does not become dissociated from the NPC alloy when the polymer is swollen, and (3) the reinforced NPC alloy composite can contain a significant amount of occluded water retained from manufacture Table 6
  • the Energy Dispersive X-Ray (EDX) analysis device of the SEM collects signals from an area of 1 ⁇ m x 1 ⁇ m at a penetration depth of about 1 ⁇ m X-ray analysis was conducted at numerous sites on the sample in Fig 6, including the NPC alloy at the center of Fig 6 Consistently at each site, peaks appeared for gold (2 1 , 8 5 keV), silicon (1 74 keV), aluminum (1 49 keV), sodium (1 04 keV), magnesium (1 25 keV), and iron (0 615, 6 40 keV) The gold peak was a result of the gold treatment for the SEM examination The relative strengths and positions of the silicon and aluminum peaks in the EDX spectra were consistent with those expected for bentonite clay All sites examined showed the presence of silicon, aluminum, sodium, magnesium and iron This analysis shows that the NPC alloy is homogeneous throughout the sample, even at the 1 ⁇ m 3 level Accordingly, the clay in the NPC alloy is chemically associated with the polymer
  • An MCX mixture was prepared by mixing 40 51 g acrylic acid with 500 g water 36 6 potassium hydroxide and 0 624 g NBAM were then added with stirring After the potassium hydroxide was in solution, 24 39 g potassium carbonate was dissolved, followed by addition of 160 33 g acrylamide, 4 83 g potassium persulfate and 500 g water 594 07 g of the monomer mixture was blended with 199 79 g bentonite clay in a flood blender to give a creamy suspension
  • the MCX mixture was polymerized by heating in a 75°C oven for 8 minutes
  • the monomer/clay mixture for Comparative Sample C was prepared by mixing 18 7 g acrylic acid, 6 1 g sodium hydroxide, 34 9 g clay and 18 g water to form a viscous paste The paste was then forced into a 2 cm x 2 cm piece of TERRAFIX ® 270R-A
  • the monomer/clay mixture could not be embedded into the geotextile at 100kPa So, one of the inventors, weighing about 80 kg, placed a piece of PLEXIGLASTM on top of the sample and stood on it while rocking back and forth About half of the monomer/clay mixture was forced into the fabric using this method No polymerization initiator or cross-linking agent was added to the monomer/clay mixture
  • the sample was dried in an oven at 75°C for one hour
  • a monomer/clay mixture was prepared by mixing 79 89 g acrylamide, 20 56 g acrylic acid, 0 3 g NBAM as cross-linking agent, 9 995 sodium hydroxide, 9 962 g sodium carbonate, and 1000 g water 552 8 g of the monomer mixture was blended with 100 55 g bentonite clay in a flood blender to give a creamy suspension No polymerization initiator was added to the monomer/clay mixture
  • Comparative Sample E was prepared by mixing 6 5 g pre-formed polyacry c acid, 1 6 g sodium hydroxide, 26 g water and 10 70 g clay The polyacryhc acid, having a molecular weight of 2,000, was obtained from Ald ⁇ ch Chemical Co
  • a layer of the pre-formed ohgomer/clay mixture was poured onto a 2 cm x 2 cm piece of TERRAFIX ® 270R-A geotextile
  • the pre-formed ohgomer/clay mixture was intimately distributed in and on the geotextile material by hand
  • the sample was dried in an oven at 75°C for one hour
  • Comparative Sample F was prepared by mixing 4 74 g pre-formed polyacryhc acid, 1 44 g sodium hydroxide, 96 g water and 11 52 g clay
  • the polyacryhc acid having a molecular weight of 450,000, was obtained from Ald ⁇ ch Chemical Co
  • a layer of the pre-formed polymer/clay mixture was poured onto a 2 cm x 2 cm piece of TERRAFIX ® 270R-A geotextile The mixture was intimately distributed in and on the geotextile material using a wooden rolling pin The sample was dried in an oven at 75°C for one hour
  • Sample A was an NPC alloy.
  • Fig. 8A illustrates the NPC alloy 36 prior to immersion in deionized water.
  • Fig. 8B illustrates the sample after 3 hours immersion in deionized water.
  • the swelled NPC alloy 38 had a puffy appearance. Substantially no clay separated from the composite.
  • Sample B was a reinforced NPC alloy composite
  • Fig 9A illustrates Sample B prior to immersion in deionized water
  • the NPC alloy is in the reinforcing agent 40
  • Fig 9B illustrates the sample after 3 hours immersion in deionized water
  • the swelled NPC alloy 46 had a puffy appearance
  • Fig 10A illustrates Comparative Sample E prior to immersion in deionized water
  • the preformed polymer and clay mixture is in the reinforcing agent 40
  • Fig 10B illustrates the sample after 3 hours immersion in deionized water
  • the polymer had dissolved in water and the clay 44 migrated off the reinforcing agent 40 and dispersed in the water Some settling of the clay 44 is observed at the bottom of the bottle
  • Table 7 and Figs 8B and 9B illustrate how the clay is an integral part of the NPC alloy
  • the results demonstrate how the NPC alloy is an integral part of the composite In all of the comparative samples, clay migrates
  • acrylamide as a monomer for preparing an NPC alloy is the leaching of any residual monomer
  • the FDA limit for leachable acrylamide in polyacrylamide is 0 05% (500 ppm, 500 ⁇ g/g) when the polyacrylamide is used in treatment of potable water and for paper and paperboard for food contact applications (EPA 600/X-85/270 July 1985, PB88-170824)
  • This example provides residual monomer data for a polymer and an NPC alloy
  • the amount of residual monomer is dependent on initiator concentration, reaction time, and reaction temperature
  • residual monomer content generally decreases with increased temperature, increased reaction time and increased initiator concentration
  • a monomer mixture was prepared by mixing 20 g acrylic acid, 80 g acrylamide, 10 g sodium hydroxide, 12 g sodium carbonate, and 0 6 g potassium persulfate in 1000 mL water
  • the monomer mixture was divided into three parts and NBAM was added as a cross-linking agent at 0 1 %, 0 3% and 0 9%, by weight, respectively
  • NBAM was added as a cross-linking agent at 0 1 %, 0 3% and 0 9%, by weight, respectively
  • Each of the three monomer mixtures was sub-divided into three parts Clay was added to some of the mixtures in an amount of about 1 1 monomer to clay or about 1 2 monomer to clay, as shown in Table 8
  • the MCX mixtures were blended in a food blender to produce a smooth, homogeneous mixture Samples of the monomer and MCX mixtures were transferred to plastic beakers and placed in an 80°C oven for one hour for polymerization The samples were removed from the oven

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Abstract

L'invention concerne un alliage polymère/argile produit à partir d'un mélange monomère/argile comprenant un monomère, un agent de réticulation et des particules d'argile. Un amorceur est utilisé pour amorcer la polymérisation du mélange monomère/argile. L'argile est chimiquement intégrée au polymère de manière qu'au contact de l'eau, le gonflement de l'alliage polymère/argile n'entraîne quasiment aucune séparation entre l'argile et l'alliage.
EP00930911A 1999-05-26 2000-05-26 Alliage polymere/argile en reseau Withdrawn EP1202797A1 (fr)

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CA2272965 1999-05-26
CA2272965 1999-05-26
PCT/CA2000/000595 WO2000072958A1 (fr) 1999-05-26 2000-05-26 Alliage polymere/argile en reseau

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DE10013217A1 (de) * 2000-03-17 2001-09-20 Basf Ag Hydrophile, quellfähige Hydrogel-bildende Polymere m it Alumosilikatanteil
KR20050036974A (ko) 2002-08-23 2005-04-20 바스프 악티엔게젤샤프트 초흡수성 중합체 및 그의 제조 방법
US6852813B2 (en) * 2002-09-25 2005-02-08 Amcol International Corporation Polymer-filled sheet material
US6783802B2 (en) 2002-09-25 2004-08-31 Amcol International Corporation Hydraulic barrier
WO2009041870A1 (fr) 2007-09-27 2009-04-02 Sca Hygiene Products Ab Gels à base d'argile réticulée par un polymère
US20100268181A1 (en) 2007-11-15 2010-10-21 Basf Se Superabsorbent Foam with Graphics on the Surface
US8419946B2 (en) 2010-04-13 2013-04-16 King Abdulaziz City For Science And Technology Method for removing heavy metals from contaminated water
US8394739B2 (en) 2010-07-14 2013-03-12 Technology Development Center, King Abdulaziz City For Science And Technology Adsorbent for adsorption of heavy metals in waste water
US9382133B2 (en) 2013-03-21 2016-07-05 King Abdulaziz City for Science and Technology (KACST) Adsorbent composite from natural raw materials to remove heavy metals from water
CN111793162A (zh) * 2020-06-28 2020-10-20 中国石油天然气股份有限公司 一种水驱井治理用双交联颗粒调堵剂
CN113480374B (zh) * 2021-08-16 2023-02-24 青岛农业大学 一种保水缓释复合肥料及其制备方法

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US4500670B1 (en) * 1983-11-22 1994-12-27 Dow Chemical Co Composite mixtures for improving gel strength of water absorbent gels
US4735987A (en) * 1986-03-25 1988-04-05 Osaka Yuki Kagaku Kogyo Kabushiki Kaisha Method for manufacture of high-expansion type absorbent polymer
JPS6328639A (ja) * 1986-07-23 1988-02-06 花王株式会社 吸液性複合体及びその製造方法
FR2614555B1 (fr) * 1987-04-28 1989-06-09 Coatex Sa Composition polymere chargee en matiere minerale pulverulente a haute capacite d'absorption en eau
GB9108942D0 (en) * 1991-04-26 1991-06-12 Courtaulds Plc Fibre
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