CA2240575A1 - Temperature-responsive materials - Google Patents
Temperature-responsive materials Download PDFInfo
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- CA2240575A1 CA2240575A1 CA 2240575 CA2240575A CA2240575A1 CA 2240575 A1 CA2240575 A1 CA 2240575A1 CA 2240575 CA2240575 CA 2240575 CA 2240575 A CA2240575 A CA 2240575A CA 2240575 A1 CA2240575 A1 CA 2240575A1
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- Prior art keywords
- temperature
- responsive polymer
- poly
- intrinsic viscosity
- exhibits
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Classifications
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- 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
- A61L15/62—Compostable, hydrosoluble or hydrodegradable materials
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/15203—Properties of the article, e.g. stiffness or absorbency
- A61F13/15211—Properties of the article, e.g. stiffness or absorbency soluble or disintegratable in liquid
-
- 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
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/15203—Properties of the article, e.g. stiffness or absorbency
- A61F13/15211—Properties of the article, e.g. stiffness or absorbency soluble or disintegratable in liquid
- A61F2013/15235—Properties of the article, e.g. stiffness or absorbency soluble or disintegratable in liquid by its solubility in water
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/15203—Properties of the article, e.g. stiffness or absorbency
- A61F2013/15284—Properties of the article, e.g. stiffness or absorbency characterized by quantifiable properties
- A61F2013/15292—Resistance, i.e. modulus or strength
- A61F2013/153—Resistance, i.e. modulus or strength in dry conditions
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/15203—Properties of the article, e.g. stiffness or absorbency
- A61F2013/15284—Properties of the article, e.g. stiffness or absorbency characterized by quantifiable properties
- A61F2013/15292—Resistance, i.e. modulus or strength
- A61F2013/15308—Resistance, i.e. modulus or strength in wet conditions, i.e. wet strength
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/51—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the outer layers
- A61F13/514—Backsheet, i.e. the impermeable cover or layer furthest from the skin
- A61F13/51401—Backsheet, i.e. the impermeable cover or layer furthest from the skin characterised by the material
- A61F2013/51409—Backsheet, i.e. the impermeable cover or layer furthest from the skin characterised by the material being a film
Landscapes
- Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Epidemiology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Materials Engineering (AREA)
- Hematology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Biomedical Technology (AREA)
- Heart & Thoracic Surgery (AREA)
- Vascular Medicine (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Absorbent Articles And Supports Therefor (AREA)
- Orthopedics, Nursing, And Contraception (AREA)
Abstract
Disclosed is a polymeric film, prepared from a temperature-responsive polymer, which exhibits flushability properties and improved strength properties when immersed in water. The film may be used in a disposable absorbent product to impart flushability properties to the product after the product's use while providing desired strength properties to the product during its use. Also disclosed is a process for preparing temperature-responsive polymers. The process prepares the temperature-responsive polymer in an aqueous solution using a chain transfer agent.
Description
CA 02240~7~ l998-06-2 WO 97/24150 PCT)US96~2f>42 TEMPERATURE-RESPONSIVE MATERIALS
~3ackqround of the Invention Field of the Invenlion The present invention relates to a polymeric fllm, prepared from a temperature-responsive polymer, which exhibits flushability properties and improved strength properties when immersed in water. The film may be used in a disposableabsorbent product to impart flushability properties to the product after the product's use while providing desired strength properties to the produc~ during its use. The present invention also relates to a process for preparing temperature-responsive polymers, The 10 process prepares the temperature-responsive polymer in an aqueous solution using a chain transfer agent.
Descri~tion of the Related Art Disposable absorbent products currently find widespread use in many applications.
15 For example, in the infant and child care areas, diapers and training pants have generally replaced ~eusable cloth absorbent articles. Other typical disposable absorbent products include feminine care products such as sanitary napkins or tampons, adult incontinence products, and health care products such as surgical drapes or wound ~ ssi, l~s. A typical disposable absorbent product generally comprises a composite structure including a 20 topshee~, a backsheet, and an absorbent structure between the topsheet and backsheet.
These products usually include some type of fastening system for fitting the product onto the wearer.
Disposable absorbent products are typically subjected to one or more liquid insults, such as of water, urine, menses, or blood, during use. As such, the outer cover 25 backsheet materials of the disposable absorbent products are typically made of liquid-insoluble and liquid impermeable materials, such as polypropylene films, that exhibit a sufflcient strength and handling capability so that the disposable absorbent product retains CA 02240~7~ 1998-06-2~
its integrity during use by a wearer and does not allow leakage of the liquid insulting the product.
Although current disposable baby diapers and other disposable absorbent productshave been generally accepted by the public, these products still have need of improvement in specific areas. For example, many disposable absorbent products can be difficult to dispose of into an aqueous environment. For example, attempts to flush many disposable absorbent products down a toilet into a sewage system typically lead to blockage of the toilet or pipes connecting the toilet to the sewage system. In particular, the outer cover materials typically used in the disposable absorbent products generally do not disintegrate or disperse when flushed down a toilet so that the disposable absorbent product cannot be disposed of in this way. If the outer cover materials are made very thin in order to reduce the overall bulk of the disposable absorbent product so as to reduce the likelihood of blockage of a toilet or a sewage pipe, then the outer cover material typically will not exhibit su~tcient strength to prevent tearing or ripping as the outer cover material is subjected to the stresses of normal use by a wearer.
As such, there is a need for new materials that are relatively easy to process and may be used in disposable absorbent products that generally retain their integrity and strength during use, but after such use, the materials may be disposed of into an aqueous environment. For example, the disposable absorbent product may be easily and efficiently disposed of by flushing the disposable absorbent product down a toilet. Such a disposable absorbent product would then be capable of being degraded by a iiquidsewage system as compared to having to be disposed of into a landfill or other solid waste disposal system.
Processes known to be useful in preparing temperature-responsive polymers include free-radical solution pol~",eri~alion, inverse suspension pol~ eri~alion, or polymerization in organic solvents. However, such processes have generally been found to result in the temperature-responsive polymer being substantially ulus~liul~ed and/or exhibiting an intrinsic viscosity that is too high so as to prevent the temperature-responsive polymer from being capable of being thermally processable.
As such, there is a need for a process that is relatively easy to use and which process results in a temperature-responsive polymer that may then be thermally processed to prepare a material form that may be used in a disposable absorbent product to impart flushability properties to the product.
CA 02240~7~ l998-06-2 WO 97/24150 PCT~US96J2~421 Summarv of the Inven~ion In one aspect, the present invention concerns a polymeric film, prepared from a temperature-responsive polymer, which exhibits flushability properties and improved strength properties when immersed in water.
In one embodiment of the present inventior" the polymeric film comprises a temperature-responsive polymer exhibiting an intrinsic viscosity less than about 50û cubic centimeters per gram, wherein the film exhibits a dry tensiJe strength of at least about 50 grams of force per 2.54 centimeters of width and a wet tensile strength that is at least about 2 percent of its dry tensile strength.
In another aspect, it is desirable to provide a thin, disposable absorbent product, such as an infant diaper, which product includes a flushable polymeric film as disclosed herein.
In one embodiment, these goals are achieved in a disposable absorbent product comprising a li~uid-permeable topsheet, a backsheet attached to the topsheet, an15 absorbent structure positioned between the topsheet and the backsheet, wherein the backsheet comprises the film of the present invention .
In another embodiment, these goals are achieved in a disposable absorbent product comprising a liquid-permeable topsheet, a backsheet attached to the topsheet, anabsorbent structure positioned between the topsheet and the backsheet, wherein the 20 topsheet comprises fibers bound together with the film of the present invention.
In another aspect, the present invention concerns a process for preparing a temperature-responsive polymer that exhibits an effectively low it~ lsic viscosity such that the temperature-responsive polymer may then be thermally processed to prepare a flushable material.
In one embodiment of the present invention, the process comprises forming a mixture comprising water, an effective amount of a chain l~dn~r~r agent, a monomer capable of being polymerized to prepare a temperature-responsive polymer, and a reaction catalyst, wherein the mixture is prepared under conditions effective to polymerize the monomer to form a temperature-responsive polymer that exhibits an intrinsic viscosity 30 that is at least about 50 percent less than the intrinsic viscosity exhibited by an otherwise substantially identical temperature-responsive polymer that is prepared without using the chain transfer agent.
In another aspect, it is desirable to provide a temperature-responsive polymer that exhibits an effectively low intrinsic viscosity such that the temperature-responsive polymer may then be thermally processed to prepare a flushable material.
CA 02240~7~ 1998-06-2~
In one embodiment, these goals are achieved in a temperature-responsive polymer that exhibits an intrinsic viscosity that is less than about 20Q cubic centimeters per gram.
Detailed DescrirJtion of the Invention In one aspect, the present invention concerns a polymeric film, prepared from a temperature-responsive polymer, which exhibits flushability properties and improved strength properties when immersed in water.
As used herein, the term "temperature-responsive polymer" is meant to represent a polymer whose water-solubility is dependent on temperature such that the polymer will be 10 generally water soluble below a specifc temperature but will be generally water insoluble above the specific temperature. As will be appreciated by those skilled in the art, the speciflc temperature upon which the water-solubility of a polymer is dependent will generally vary from polymer to polymer. For purposes of the present invention, it is generally desired that the temperature upon which the water-solubility of a polymer is 15 dependent will desirably be between about 20~C to about 65~C, suitably between about 20~C to about 35~C, more suitably between about 23~C to about 28~C, and most suitably about 24~C.
EX~IIIPIES of polymers that are temperature-responsive include, but are not limited to, poly(N-substituted acrylalll.dcs) such as poly(N-isopropylacrylamide), poly(N-propylacrylamide), poly(N-ethoxypropylacrylamide), and poly(N,N-diethylacrylamide), and poly(N-substituted methacrylamides) such as poly(N-isopropyl methacrylamide) and poly(N-ethoxypropyl methacrylamide). In addition, copolymers of these materials may also be prepared that is temperature-responsive.
Copolymerization may permit the selection and commingling of advantageous properties of various polymers.
The temperature-responsive polymer useful in the present invention desirably exhibits effective intrinsic viscosity properties. In particular, the temperature-responsive polymer prepared by the process of the present invention exhibits significantly lower3 intrinsic viscosity values as compared to known temperature-responsive polymers.As such, the temperature-responsive polymer of the present invention exhibits anintrinsic viscosity that is beneficially less than about 500 cubic centimeters per gram, suitably less than about 300 cubic centimeters per gram, more suitably less than about 200 cubic centimeters per gram, and most suitably less than about 100 cubic centimeters per gram.
3~ Because the temperature-responsive polymer of the present invention exhibits effective intrinsic viscosity values, the temperature-responsive polymer is capable of being CA 02240~7~ 1998-06-2~
WO 97124~150 PCTJU~96J2~)4211 thermally processed to form such materials as flbers, films, and other thermally processed forms of the temperature-responsive polymer. Such a thermal process may include, for example, thermal extrusion. Those skilled in the art will recogni~e that the intrinsic viscosity may be adjusted according to the particular form in which the temperature-responsive poiymer is used.
When a temperature-responsive polymer of the present invention is to be used in a disposable absorbent product as, for example, in a backsheet corilposile, the temperature-responsive polymer is desirably used in the form of a thin polymeric film.
Desirably, such a thin polymeric film exhibits both effective dry and wet tensile strengths 10 such that the thin polymeric film retains its integrity and strength during use.
A material will often exhibit a different tensile strength when in a dry condition as compared to when the " ,al~l ial is in a wet condition. This is because the liquid saturating the material will often interact with the material and affect the elastic properties of the material. As will be recognized by one skilled in the art, such a difference in the tensile 15 strength values for a ulal~rial when in a dry conclilion as com,ua~d to when the material is in a wet condition will depend on the composition and structure of the material.As will be appreciated by one skilled in the art, a material such as a polymeric film may entrap a relatively minor amount of liquid, such as water, within the material prior to use. For example, such liquid may be absorbed by the polymeric film from humidity in the 20 air. Such a material is still intended to be considered in a dry condition for purposes of the present invention. Thus, as used herein, the "dry" condition of a material is meant to represent that the material comprises an amount of water that is suitably less than about 5 weight percent, more suitably less than about 3 weight percent, and most suitably less than about 1 weight percent, based on the total weight of the material.
As used herein, the "wet" condition of a material is meant to represent that then ,al~rial comprises an amount of water that is about 100 percent of the absolute liquid saturated retention capacity of the material which may be obtained after the material has been allowed to soak in an excess of water until fully hydrated at a temperature about 5~C
above the temperature at which the change in water-solubility of the material is30 dependent.
It is desired that a polymeric film of the present invention, having a thickness of about 0.002 inch, exhibits a dry tensile strength that is beneficially at least about 50 grams of force, suitably at least about 100 grams of force, and more suitably at least about 200 grams of force per 2.54 centimeters of width of the film.
It is also desired that a polymeric film of the present invention, having a thickness of about 0.002 inch, exhibits a wet tensile strength that is beneficially at least about 2 CA 02240~7~ l998-06-2~
percent, suitably at least about 5 percent, more suitably at least about 7 percent, and most suitably at least about 10 percent of the dry tensile strength exhibited by the material. The tensile strengths of a material may be determined using a commercial tensile tester.
The present invention includes a process for preparing a temperature-responsive polymer that exhibits an effectively low intrinsic viscosity such that the temperature-responsive polymer may then be thermally processed to prepare a flushable material.
The process of the present invention generally comprises forming a mixture comprising water, an effective amount of a chain trans~er agent, a monomer capable of being polymerized to prepare a temperature-responsive polymer, and a reaction catalyst, wherein the mixture is prepared under conditions effective to polymerize the monomer to form a temperature-responsive polymer that exhibits an intrinsic viscosity that is at least about 50 percent less than the intrinsic viscosity exhibited by an otherwise substantially identical temperature-responsive polymer that is prepared without using a chain transfer agent such as isopropanol.
The reaction mixture is typically prepared with an aqueous mixture beneficially comprising at least about 30 weight percent water, suitably at least about 50 weight percent water, more suitably at least about 75 weight percent water, and most suitably about 100 weight percent water. When another liquid is employed with the water, such other suitable liquids include methanol, ethanol, and acetone. However, the use or presence of such other non-aqueous liquids may impede the formation of a reaction mixture that results in a temperature-responsive polymer that exhibits an effective i, Illil ,sic viscosity as described herein.
Generally, the order of mixing of the water, chain transfer agent, a reaction catalyst, and monomers capable of undergoing free radical polyl"eri~dlion is not critical in the process of the present invention. However, it may be benehcial to hrst add the chain transfer agent to the water, then add the monomers to the solution, and finally add a reaction catalyst.
A chain transfer agent suitable for use in the present invention includes isopropanol and water-soluble thiols. The chain transfer agent should be used in an amount effective to result in a temperature-responsive polymer that exhibits an effective intrinsic viscosity as described herein. Generally, the chain transfer agent will be used in an amount that is benehcially within the range of greater than 0 volume percent to about 50 volume percent of the reaction mixture, suitably from about 1 volume percent to about 40 volume percent CA 02240~7~ 1998-06-2~
WO 97124150 PCTllJS9~20420 of the reaction mixture, and more suitably from about 5 volume percent to about 30 volume percent o~ the reaction mixture.
A reaction catalyst suitable for use in the present invention includes potassiumpersulfate. The reaction catalyst should be used in an amount effective to result in a 5 temperature-responsive polymer that exhibits an effective intrinsic viscosity as described herein. Generally, the reaction catalyst will be used in an amount that is beneficially within the range of about 0.001 mole percent to about 1 mole percent, suitably from about Q.01 mole percent to about 0.8 mole percent of the reaction mixture, and more suitably from about 0.02 mole percent to about 0.6 mole percent.
The reaction mixture should be prepared under conditions effective to polymerizethe monomer to form a temperature-responsive polymer that exhibits a desired intrinsic viscosity. Thus, the mixture can generally be prepared at any combination of temperature and pressure effective to form the desired temperature-responsive polymer. Generally, such temperatures will beneficially be within the range of from about 1 O~C to about 1 00~C
15 and suitably within the range of from about 20~C to about 80~C.
It has been found that the temperature-responsive polymer prepared by the p,ucess of the present invention, wherein a chain transfer agent such as isop,upanol is used, exhibil~i surprisingiy improved intrinsic viscosity properties. In particular, the temperature-responsive polymer prepared by the process of the present invention exhibits 20 significantly lower intrinsic viscosity values as compared to an otherwise substantially identical temperature-responsive polymer that is prepared without using the chain ll~nsrer agent.
As such, the temperature-responsive polyrner prepared using the process of the present invention exhibits an intrinsic viscosity that is beneficially less than about 200 25 cubic centimeters per gram, suitably less than about 150 cubic centimeters per gram, more suitably less than about 100 cubic centimeters per gram, and most suitably less than about 75 cubic centimeters per gram. In addition, the temperature-responsive polymer of the present invention exhibits an intrinsic viscosity that is beneficially less than about 5û percent, suitably less than about 40 percent, more suitably less than about 30 30 percent, and most suitably less than about 20 percent of the illl,i"sic viscosity exhibited by an otherwise substantially identical temperature-responsive polymer that is prepared without using the chain transfer agent.
As used herein, the term "an otherwise sub~l~nli~lly identical temperature-responsive polymer that is prepared without using a chain transfer agent" or 35 other similar terms are intended to refer to a control temperature-responsive polymer that is prepared using substantially identical materials and a sub~tal,lial;y identical process as CA 02240~7~ 1998-06-2~
WO 97t24150 PCT/US96/20420 compared to a temperature-responsive poiymer of the present invention, except that the control temperature-responsive polymer is prepared by a process that does not use a chain l~ansrer agent as described herein. As a result of not being prepared according to the method of the present invention, the control temperature-responsive polymer 5 generally will not exhibit the improved i"l, il ,sic viscosity properties as described herein.
Because the temperature-responsive polymer of the present invention exhibits improved il ,ll il Isic viscosity values, the temperature-responsive polymer is capable of being thermally processed to form such materials as fibers, films, and other thermally processed forms of the temperature-responsive polymer. Such a thermal process may 10 include, for example, thermal extrusion.
In one embodiment of the present invention, a disposable absorbent product is provided, which disposable absorbent product coll~,~rises a liquid-perl"eable topsheet, a backsheet attached to the topsheet, an absorbent structure positioned between the topsheet and the backsheet, wherein the backsheet comprises a temperature-responsive 15 polymer prepared by the process of the present invention.
Those skilled in the art will recoy~ materials suitable for use as the topsheet and backsheet. Exemplary of materials suitable for use as the topsheet are liquid-permeable le,ials, such as spunbonded polypropylene or polyethylene having a basis weight of from about 15 to about 2~ grams per square meter. Exemplary of materials suitable for 20 use as the backsheet, in addition to the temperature-responsive polymer of the present invention, are liquid-impervious materials, such as polyolefin films, as well as vapor-pervious materials, such as microporous polyolefin films.
The temperature-responsive polymer of the present invention will generally be employed in a disposable absorbent product comprising an absorbent structure. Such an 2~ absorbent structure will generally comprise a fibrous matrix into which an absorbent material such as, for example, a hydrogel-forming polymeric material is dispersed such that the fibrous matrix constrains or entraps the absorbent material.
The fibrous matrix may be formed by air-laying fibers, through a spunbond or meltblown process, a carding process, a wet-laid prucess, or through essentially any other 30 means, known to those skilled in the art, for forming a fibrous matrix.
Methods of incorporating an absorbent material into a fibrous matrix are known to those skilled in the art. Suitable methods include incorporating an absorbent material into the matrix during formation of the matrix, such as by air laying the fibers of the fibrous matrix and the absorbent material at the same time or wet-laying the fibers of the fibrous 3~ matrix and the absorbent material at the same time. Alternatively, it is possible to apply the absorbent material to the fibrous matrix after formation of the fibrous matrix. Other CA 02240~7~ 1998-06-2~
WO 97J2415~ PCT)US96J20420 methods include sandwiching the absorbent material behNeen two sheets of IlldL~ i, at least one of which is fibrous and iiquid permeable. The absorbent material may be generally uniformly located between the two sheets of material or may be located in discrete pockets formed by the two sheets. The absorbent material may be distributed in 5 the individual layers in a generally uniform manner or may be present in the fibrous layers as a layer or other nonuniform distribution.
The fibrous matrix may be in the form of a single, integrally formed layer or of a composite comprising multiple layers. If the fibrous matrix co" ,~,ri ,es multiple layers, the layers are preferably in liquid communication with one another such that a liquid present in 10 one flbrous layer can flow or be transported to the other fibrous layer. For example, the fibrous layers may be separated by cellulosic tissue wrap sheets known to those skilled in the art.
When the fibrous matrix comprises a single, integrally formed layer, the concentration of absorbent material may increase along the thickness of the fibrous matrix 15 in a gradual, nonstepwise fashion or in a more stepwise fashion. Similarly, the density may decrease through the thickness in a nonstepwise manner or in a stepwise manner.
Absorbent structures may generally be of any size or dimension as long as the absu, bent structure exhibits desired absorbent characteristics.
Absorbent structures are generally suited to absorb many liquids, such as water,20 saline, and synthetic urine, and body liquids such as urine, menses, and blood, and are suited for use in disposable absorbent products such as diapers, adult incontinent products, and bed pads; in calarnenial devices such as sanitary napkins, and tampons;
and in other absorbent products such as wipes, bibs, wound dressings, and surgical capes or drapes.
Disposable absorbent products, according to all aspects of the present invention, are generally subjected during use to multiple insults of a body liquid. Accordingly, the disposable absorbent products are desirably capable of absorbing multiple insults of body liquids in quantities to which the absorbent products and structures will be exposed during use. The insults are generally separated from one another by a period of time.
A~ter the disposable absorbent product has been used, it will be desirable to dispose of the disposable absorbent product. If the disposable absorbent product includes the temperature-responsive polymer of the present invention, it may be possible to dispose of t the product directly to a liquid disposal system, such as by disposing of the product into a toilet. When placed into a toilet, an excess of water will generally be present and the 35 temperature of the water will generally be lower than the temperature of the li~uid insulting the product such that the temperature-responsive polymer of the present invention may CA 02240~7~ 1998-06-2~
rapidly disperse into the water. The disposable absorbent product may then be capable of being flushed down the toilet without fear of the disposable absorbent product clogging the piping of the toilet. By this method of disposal, the disposable absorbent product may then be successfully treated and degraded by the sewage system to which the toilet is attached instead of disposing of the disposable absorbent product through a solid waste disposable system. By not having to be disposed of through a solid waste disposable system, the use of the temperature-responsive polymer of the present invention may reduce the amount of solid waste that has to be landfilled, incinerated, or otherwise disposed of.
Test Methods Intrinsic Viscositv Intrinsic viscosity is a parameter which directiy reflects the molecular properties of a dissolved polymer. For a flexible polymer the i, Illil Isic viscosity is related to Ma where M
15 represents the molecular weight of the polymer and 0.50 ~ a < 0.80. Intrinsic viscosity ([tl]) is calculated using the following equations:
(~11]) = lim (1/c) {(~ o3- 1} Equation 1 c~o wherein:
~ = the solution viscosity at a given polymer concentration llo = the solvent viscosity and:
O = t/to Equation 2 wherein:
t = the time for a polymer solution to flow through a viscometer to = the time for a solvent to flow through a viscometer A Canon Fenske viscometer was used to measure the relative viscosity of a polymer solution with respect to viscosity of deionized water, which was used as the solvent.
Viscometer numbers 100 and 150 were used. The flow time for deionized water at room 30 temperature for viscometer number 100 was about 58.5 seconds and that for viscometer number 150 was about 28.5 seconds. Higher viscosity polymer samples, such as poly(N-iospropylacrylamide), were studied using viscometer number 150 and iower viscosity polymer samples were studied using viscometer number 100.
The relative viscosities for a polymer sample were measured at 5 different polymer concentrations. The right hand side of Equation 1 (y-axis) was plotted against polymer CA 02240~7~ l998-06-2 WO 97/24150 PCTJUS96/2~42~
concentration (x-axis). On extrapolation to zero concentration, the intercept on the y-axis yields the intrinsic viscosity for the polymer sample.
Water Solubilitv TemPerature Polymers that are temperature responsive exhibit cloud points wherein the polymer precipitates out of solution on heating the solution above the cloud point. On precipitation the solu$ion turns turbid and the cloud point can be measured. Solutions containing between about 0.2 weight percent to about 1.0 weight percent are used for determining the water solubility temperature for a polymer. The solution was poured into a scintillation 10 vial. A thermometer was dipped into this solution and clamped in position with the help of a laboratory stand. A small magnetic stirrer was used for agitation. The solution in the vial was heated at a temperature increase of about 1~C per minute. The temperature at which the thermometer bulb became invisible due to solution turbidity was recorded as the cloud point.
1~
Pry Tensile Strength Dry tensile strength measurements were performed on a Sintech 1/D tensile testing system. Fiim samples, having a thickness of about 0.002 inch and prepared from apolymer sample, was cut to a width of about 0.75 inch. The distance between the grips of 20 the tensile tester was about 1.5 inch. The stretch rate of the grips was about 3 millimeters per second.
Wet Tensile Strength Wet tensile strength measurements were performed in deionized water using a 25 Vitrodyne V1000 mini-tensile tester with the testing speed of about 3 millimeters per second. The distance between the grips of the tensile tester was about 1.5 inch. Film samples, having a thickness of about 0.002 inch and prepared from a polymer sample, was cut to a width of about 1.0 inch. The wet tensile strength measurements wereperformed in cold water at ambient temperature and in warm water at temperatures about 30 5~C above the water solubility temperature of polymer san"~les. The samples were immersed in water for about 30 seconds before testing in the tensile tester for the binder testing and for about 5 minutes before testing in the tensile tester for the film testing.
CA 02240~7~ 1998-06-2~
Examr les Exam~le 1 To a 0.45 M aqueous solution of N-isopropylacrylamide, available from Eastman Chemical Company, was added 0.4 mole percent potassium persulfate, available from 5 Aldrich Chemical Company, at about room temperature (about 23~C) under a nitrogen atmosphere. The reaction was aliowed to proceed for about 8 hours at about 30~C. The polymer was removed from the reaction mixture by heating the mixture above the cloud point of the polymer so that the polymer could be recovered. The polymer was then washed with warm water and dried under vacuum. The yield of the polymer was about 50 10 percent. The prepared polymer was found to exhibit an intrinsic viscosity of about 437 cubic centimeters per gram. Because of its high intrinsic viscosity, the polymer was not thermally processable.
Exam~le 2 About 22.8 grams (about 0.2 mole) of N-isopropylacrylamide was dissolved in about 200 milliliters of deionized water at about room temperature (about 23~C) under a nitrogen aLI,lospl-ere. The solution was heated to about 55~C and about 0.123 gram (about 0.0004 mole) of potassium persulfate was added to the solution at once. A white precipitate was observed to form immediately in the solution. The reaction was allowed to proceed for 20 about 4 hours at about 55~C. The polymer was then removed from the reaction vessel, washed with warm water, and dried under vacuum at about 50~C to a constant weight.
The yield of the polymer was quantitative. The polymer was placed into water andallowed to stand for about 48 hours at the end of which gel particles of the polymer were still observed. Since the polymer was not completely soluble in water, the polymer was 25 believed to be crosslinked.
Exam~le 3 About 113.1 grams (about 1 mole) of N-isopropylacrylamide was dissolved in a mixture of about 712 milliliters of deionized water and about 38 milliliters of isopropanol 30 (about 5 percent by volume~, available from Mallinchrodt Specialty Chemicals Company, at about room temperature (about 23~C) under a nitrogen atmosphere. The solution was heated to about 52~C and potassium persulfate was added to the solution at once. The solution was observed to become cloudy in a few minutes. The temperature of the mixture increased to about 68~C, believed to be because of the heat generated during the 35 polymerization. The reaction was allowed to proceed for about 4 hours. The polymer was CA 02240~7~ 1998-06-2~
WO 9712d,150 PCT~US96/20420 then removed from the reaction vessel, washed with warm water, and dried under vacuum at about 50OC to a constant weight. The yield of the polymer was quantitative. Th polymer was completely water soluble in water, indicating essentially no .;~ ussl;, Ihi~ ,9 of the polymer. The prepared polymer was found to exhibit an intrinsic viscosity of about 131 cubic centimeters per gram. Fibers with good mechanical strength and clarity were prepared using the polymer in a thermal extrusion process.
Example 4 A process similar to that described in Example 3 was used except that about 10 10 percent by volume of isopropanol was used to prepare the initial mixture with water.
The prepared polymer was found to exhibit an intrinsic viscosity of about 83 cubic centimeters per gram. Fibers with good mechanical strength and clarity were prepared using the polymer in a thermal extrusion process.
15 ExamPle 5 A process similar to that described in Example 3 was used except that about 15 percent by volume of isopropanol was used to prepare the initial mixture with water.
The prepared polymer was found to exhibit an intrinsic viscosity of about 68 cubic centimeters per gram. Fibers with good mechanical strength and clarity were prepared 20 using the polymer in a thermal extrusion process.
F~amPle 6 A process similar to that described in Example 3 was used except that about 20 percent by volume of isopropanol was used to prepare the initial mixture with water.
25 The prepared polymer was found to exhibit an intrinsic viscosity of about ~0 cubic centimeters per gram. Fibers with good mechanical sllenyll, and clarity were prepared using the polymer in a thermal extrusion process.
ExamPle 7 To an about 1 M aqueous solution of N,N-diethylacrylamide was added about 0.2 mole percent potassium persulfate at about room temperature (about 23~C) under a nitrogen atmosphere. The reaction was allowed to proceed for about 24 hours at about 21 .B~C. The polymer was precipitated in warm water, washed with warm water, and dried under vacuum. The prepared polymer was found to exhibit an intrinsic viscosity of about 292 cubic centimeters per gram.
CA 02240~7~ 1998-06-2~
WO 97/24150 PCT/US96/2~)420 ~xam~le 8 About 41.3 grams (about 0.325 mole) of N,N-diethylacrylamide was dissolved in a mixture of about 244 milliliters of deionized water and about 27 milliliters of isopropanol.
5 The solution was purged with nitrogen at about 65~C for about 30 minutes. Potassium persulfate (about 0.18 gram; about 0.00065 mole) was added to the solution at once. The reaction was allowed to proceed for about 3 hours. The polymer was then removed from the reaction vessel, washed with warm water, and dried under vacuum. The prepared polymer was found to exhibit an intrinsic viscosity of about 23 cubic centimeters per gram.
While the invention has been described in detail with respect to speci~lc embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to, variations of, and equivalents to these embodiments. Accordingly, the scope of the present invention 15 should be assessed as that of the appended claims and any equivalents thereto.
~3ackqround of the Invention Field of the Invenlion The present invention relates to a polymeric fllm, prepared from a temperature-responsive polymer, which exhibits flushability properties and improved strength properties when immersed in water. The film may be used in a disposableabsorbent product to impart flushability properties to the product after the product's use while providing desired strength properties to the produc~ during its use. The present invention also relates to a process for preparing temperature-responsive polymers, The 10 process prepares the temperature-responsive polymer in an aqueous solution using a chain transfer agent.
Descri~tion of the Related Art Disposable absorbent products currently find widespread use in many applications.
15 For example, in the infant and child care areas, diapers and training pants have generally replaced ~eusable cloth absorbent articles. Other typical disposable absorbent products include feminine care products such as sanitary napkins or tampons, adult incontinence products, and health care products such as surgical drapes or wound ~ ssi, l~s. A typical disposable absorbent product generally comprises a composite structure including a 20 topshee~, a backsheet, and an absorbent structure between the topsheet and backsheet.
These products usually include some type of fastening system for fitting the product onto the wearer.
Disposable absorbent products are typically subjected to one or more liquid insults, such as of water, urine, menses, or blood, during use. As such, the outer cover 25 backsheet materials of the disposable absorbent products are typically made of liquid-insoluble and liquid impermeable materials, such as polypropylene films, that exhibit a sufflcient strength and handling capability so that the disposable absorbent product retains CA 02240~7~ 1998-06-2~
its integrity during use by a wearer and does not allow leakage of the liquid insulting the product.
Although current disposable baby diapers and other disposable absorbent productshave been generally accepted by the public, these products still have need of improvement in specific areas. For example, many disposable absorbent products can be difficult to dispose of into an aqueous environment. For example, attempts to flush many disposable absorbent products down a toilet into a sewage system typically lead to blockage of the toilet or pipes connecting the toilet to the sewage system. In particular, the outer cover materials typically used in the disposable absorbent products generally do not disintegrate or disperse when flushed down a toilet so that the disposable absorbent product cannot be disposed of in this way. If the outer cover materials are made very thin in order to reduce the overall bulk of the disposable absorbent product so as to reduce the likelihood of blockage of a toilet or a sewage pipe, then the outer cover material typically will not exhibit su~tcient strength to prevent tearing or ripping as the outer cover material is subjected to the stresses of normal use by a wearer.
As such, there is a need for new materials that are relatively easy to process and may be used in disposable absorbent products that generally retain their integrity and strength during use, but after such use, the materials may be disposed of into an aqueous environment. For example, the disposable absorbent product may be easily and efficiently disposed of by flushing the disposable absorbent product down a toilet. Such a disposable absorbent product would then be capable of being degraded by a iiquidsewage system as compared to having to be disposed of into a landfill or other solid waste disposal system.
Processes known to be useful in preparing temperature-responsive polymers include free-radical solution pol~",eri~alion, inverse suspension pol~ eri~alion, or polymerization in organic solvents. However, such processes have generally been found to result in the temperature-responsive polymer being substantially ulus~liul~ed and/or exhibiting an intrinsic viscosity that is too high so as to prevent the temperature-responsive polymer from being capable of being thermally processable.
As such, there is a need for a process that is relatively easy to use and which process results in a temperature-responsive polymer that may then be thermally processed to prepare a material form that may be used in a disposable absorbent product to impart flushability properties to the product.
CA 02240~7~ l998-06-2 WO 97/24150 PCT~US96J2~421 Summarv of the Inven~ion In one aspect, the present invention concerns a polymeric film, prepared from a temperature-responsive polymer, which exhibits flushability properties and improved strength properties when immersed in water.
In one embodiment of the present inventior" the polymeric film comprises a temperature-responsive polymer exhibiting an intrinsic viscosity less than about 50û cubic centimeters per gram, wherein the film exhibits a dry tensiJe strength of at least about 50 grams of force per 2.54 centimeters of width and a wet tensile strength that is at least about 2 percent of its dry tensile strength.
In another aspect, it is desirable to provide a thin, disposable absorbent product, such as an infant diaper, which product includes a flushable polymeric film as disclosed herein.
In one embodiment, these goals are achieved in a disposable absorbent product comprising a li~uid-permeable topsheet, a backsheet attached to the topsheet, an15 absorbent structure positioned between the topsheet and the backsheet, wherein the backsheet comprises the film of the present invention .
In another embodiment, these goals are achieved in a disposable absorbent product comprising a liquid-permeable topsheet, a backsheet attached to the topsheet, anabsorbent structure positioned between the topsheet and the backsheet, wherein the 20 topsheet comprises fibers bound together with the film of the present invention.
In another aspect, the present invention concerns a process for preparing a temperature-responsive polymer that exhibits an effectively low it~ lsic viscosity such that the temperature-responsive polymer may then be thermally processed to prepare a flushable material.
In one embodiment of the present invention, the process comprises forming a mixture comprising water, an effective amount of a chain l~dn~r~r agent, a monomer capable of being polymerized to prepare a temperature-responsive polymer, and a reaction catalyst, wherein the mixture is prepared under conditions effective to polymerize the monomer to form a temperature-responsive polymer that exhibits an intrinsic viscosity 30 that is at least about 50 percent less than the intrinsic viscosity exhibited by an otherwise substantially identical temperature-responsive polymer that is prepared without using the chain transfer agent.
In another aspect, it is desirable to provide a temperature-responsive polymer that exhibits an effectively low intrinsic viscosity such that the temperature-responsive polymer may then be thermally processed to prepare a flushable material.
CA 02240~7~ 1998-06-2~
In one embodiment, these goals are achieved in a temperature-responsive polymer that exhibits an intrinsic viscosity that is less than about 20Q cubic centimeters per gram.
Detailed DescrirJtion of the Invention In one aspect, the present invention concerns a polymeric film, prepared from a temperature-responsive polymer, which exhibits flushability properties and improved strength properties when immersed in water.
As used herein, the term "temperature-responsive polymer" is meant to represent a polymer whose water-solubility is dependent on temperature such that the polymer will be 10 generally water soluble below a specifc temperature but will be generally water insoluble above the specific temperature. As will be appreciated by those skilled in the art, the speciflc temperature upon which the water-solubility of a polymer is dependent will generally vary from polymer to polymer. For purposes of the present invention, it is generally desired that the temperature upon which the water-solubility of a polymer is 15 dependent will desirably be between about 20~C to about 65~C, suitably between about 20~C to about 35~C, more suitably between about 23~C to about 28~C, and most suitably about 24~C.
EX~IIIPIES of polymers that are temperature-responsive include, but are not limited to, poly(N-substituted acrylalll.dcs) such as poly(N-isopropylacrylamide), poly(N-propylacrylamide), poly(N-ethoxypropylacrylamide), and poly(N,N-diethylacrylamide), and poly(N-substituted methacrylamides) such as poly(N-isopropyl methacrylamide) and poly(N-ethoxypropyl methacrylamide). In addition, copolymers of these materials may also be prepared that is temperature-responsive.
Copolymerization may permit the selection and commingling of advantageous properties of various polymers.
The temperature-responsive polymer useful in the present invention desirably exhibits effective intrinsic viscosity properties. In particular, the temperature-responsive polymer prepared by the process of the present invention exhibits significantly lower3 intrinsic viscosity values as compared to known temperature-responsive polymers.As such, the temperature-responsive polymer of the present invention exhibits anintrinsic viscosity that is beneficially less than about 500 cubic centimeters per gram, suitably less than about 300 cubic centimeters per gram, more suitably less than about 200 cubic centimeters per gram, and most suitably less than about 100 cubic centimeters per gram.
3~ Because the temperature-responsive polymer of the present invention exhibits effective intrinsic viscosity values, the temperature-responsive polymer is capable of being CA 02240~7~ 1998-06-2~
WO 97124~150 PCTJU~96J2~)4211 thermally processed to form such materials as flbers, films, and other thermally processed forms of the temperature-responsive polymer. Such a thermal process may include, for example, thermal extrusion. Those skilled in the art will recogni~e that the intrinsic viscosity may be adjusted according to the particular form in which the temperature-responsive poiymer is used.
When a temperature-responsive polymer of the present invention is to be used in a disposable absorbent product as, for example, in a backsheet corilposile, the temperature-responsive polymer is desirably used in the form of a thin polymeric film.
Desirably, such a thin polymeric film exhibits both effective dry and wet tensile strengths 10 such that the thin polymeric film retains its integrity and strength during use.
A material will often exhibit a different tensile strength when in a dry condition as compared to when the " ,al~l ial is in a wet condition. This is because the liquid saturating the material will often interact with the material and affect the elastic properties of the material. As will be recognized by one skilled in the art, such a difference in the tensile 15 strength values for a ulal~rial when in a dry conclilion as com,ua~d to when the material is in a wet condition will depend on the composition and structure of the material.As will be appreciated by one skilled in the art, a material such as a polymeric film may entrap a relatively minor amount of liquid, such as water, within the material prior to use. For example, such liquid may be absorbed by the polymeric film from humidity in the 20 air. Such a material is still intended to be considered in a dry condition for purposes of the present invention. Thus, as used herein, the "dry" condition of a material is meant to represent that the material comprises an amount of water that is suitably less than about 5 weight percent, more suitably less than about 3 weight percent, and most suitably less than about 1 weight percent, based on the total weight of the material.
As used herein, the "wet" condition of a material is meant to represent that then ,al~rial comprises an amount of water that is about 100 percent of the absolute liquid saturated retention capacity of the material which may be obtained after the material has been allowed to soak in an excess of water until fully hydrated at a temperature about 5~C
above the temperature at which the change in water-solubility of the material is30 dependent.
It is desired that a polymeric film of the present invention, having a thickness of about 0.002 inch, exhibits a dry tensile strength that is beneficially at least about 50 grams of force, suitably at least about 100 grams of force, and more suitably at least about 200 grams of force per 2.54 centimeters of width of the film.
It is also desired that a polymeric film of the present invention, having a thickness of about 0.002 inch, exhibits a wet tensile strength that is beneficially at least about 2 CA 02240~7~ l998-06-2~
percent, suitably at least about 5 percent, more suitably at least about 7 percent, and most suitably at least about 10 percent of the dry tensile strength exhibited by the material. The tensile strengths of a material may be determined using a commercial tensile tester.
The present invention includes a process for preparing a temperature-responsive polymer that exhibits an effectively low intrinsic viscosity such that the temperature-responsive polymer may then be thermally processed to prepare a flushable material.
The process of the present invention generally comprises forming a mixture comprising water, an effective amount of a chain trans~er agent, a monomer capable of being polymerized to prepare a temperature-responsive polymer, and a reaction catalyst, wherein the mixture is prepared under conditions effective to polymerize the monomer to form a temperature-responsive polymer that exhibits an intrinsic viscosity that is at least about 50 percent less than the intrinsic viscosity exhibited by an otherwise substantially identical temperature-responsive polymer that is prepared without using a chain transfer agent such as isopropanol.
The reaction mixture is typically prepared with an aqueous mixture beneficially comprising at least about 30 weight percent water, suitably at least about 50 weight percent water, more suitably at least about 75 weight percent water, and most suitably about 100 weight percent water. When another liquid is employed with the water, such other suitable liquids include methanol, ethanol, and acetone. However, the use or presence of such other non-aqueous liquids may impede the formation of a reaction mixture that results in a temperature-responsive polymer that exhibits an effective i, Illil ,sic viscosity as described herein.
Generally, the order of mixing of the water, chain transfer agent, a reaction catalyst, and monomers capable of undergoing free radical polyl"eri~dlion is not critical in the process of the present invention. However, it may be benehcial to hrst add the chain transfer agent to the water, then add the monomers to the solution, and finally add a reaction catalyst.
A chain transfer agent suitable for use in the present invention includes isopropanol and water-soluble thiols. The chain transfer agent should be used in an amount effective to result in a temperature-responsive polymer that exhibits an effective intrinsic viscosity as described herein. Generally, the chain transfer agent will be used in an amount that is benehcially within the range of greater than 0 volume percent to about 50 volume percent of the reaction mixture, suitably from about 1 volume percent to about 40 volume percent CA 02240~7~ 1998-06-2~
WO 97124150 PCTllJS9~20420 of the reaction mixture, and more suitably from about 5 volume percent to about 30 volume percent o~ the reaction mixture.
A reaction catalyst suitable for use in the present invention includes potassiumpersulfate. The reaction catalyst should be used in an amount effective to result in a 5 temperature-responsive polymer that exhibits an effective intrinsic viscosity as described herein. Generally, the reaction catalyst will be used in an amount that is beneficially within the range of about 0.001 mole percent to about 1 mole percent, suitably from about Q.01 mole percent to about 0.8 mole percent of the reaction mixture, and more suitably from about 0.02 mole percent to about 0.6 mole percent.
The reaction mixture should be prepared under conditions effective to polymerizethe monomer to form a temperature-responsive polymer that exhibits a desired intrinsic viscosity. Thus, the mixture can generally be prepared at any combination of temperature and pressure effective to form the desired temperature-responsive polymer. Generally, such temperatures will beneficially be within the range of from about 1 O~C to about 1 00~C
15 and suitably within the range of from about 20~C to about 80~C.
It has been found that the temperature-responsive polymer prepared by the p,ucess of the present invention, wherein a chain transfer agent such as isop,upanol is used, exhibil~i surprisingiy improved intrinsic viscosity properties. In particular, the temperature-responsive polymer prepared by the process of the present invention exhibits 20 significantly lower intrinsic viscosity values as compared to an otherwise substantially identical temperature-responsive polymer that is prepared without using the chain ll~nsrer agent.
As such, the temperature-responsive polyrner prepared using the process of the present invention exhibits an intrinsic viscosity that is beneficially less than about 200 25 cubic centimeters per gram, suitably less than about 150 cubic centimeters per gram, more suitably less than about 100 cubic centimeters per gram, and most suitably less than about 75 cubic centimeters per gram. In addition, the temperature-responsive polymer of the present invention exhibits an intrinsic viscosity that is beneficially less than about 5û percent, suitably less than about 40 percent, more suitably less than about 30 30 percent, and most suitably less than about 20 percent of the illl,i"sic viscosity exhibited by an otherwise substantially identical temperature-responsive polymer that is prepared without using the chain transfer agent.
As used herein, the term "an otherwise sub~l~nli~lly identical temperature-responsive polymer that is prepared without using a chain transfer agent" or 35 other similar terms are intended to refer to a control temperature-responsive polymer that is prepared using substantially identical materials and a sub~tal,lial;y identical process as CA 02240~7~ 1998-06-2~
WO 97t24150 PCT/US96/20420 compared to a temperature-responsive poiymer of the present invention, except that the control temperature-responsive polymer is prepared by a process that does not use a chain l~ansrer agent as described herein. As a result of not being prepared according to the method of the present invention, the control temperature-responsive polymer 5 generally will not exhibit the improved i"l, il ,sic viscosity properties as described herein.
Because the temperature-responsive polymer of the present invention exhibits improved il ,ll il Isic viscosity values, the temperature-responsive polymer is capable of being thermally processed to form such materials as fibers, films, and other thermally processed forms of the temperature-responsive polymer. Such a thermal process may 10 include, for example, thermal extrusion.
In one embodiment of the present invention, a disposable absorbent product is provided, which disposable absorbent product coll~,~rises a liquid-perl"eable topsheet, a backsheet attached to the topsheet, an absorbent structure positioned between the topsheet and the backsheet, wherein the backsheet comprises a temperature-responsive 15 polymer prepared by the process of the present invention.
Those skilled in the art will recoy~ materials suitable for use as the topsheet and backsheet. Exemplary of materials suitable for use as the topsheet are liquid-permeable le,ials, such as spunbonded polypropylene or polyethylene having a basis weight of from about 15 to about 2~ grams per square meter. Exemplary of materials suitable for 20 use as the backsheet, in addition to the temperature-responsive polymer of the present invention, are liquid-impervious materials, such as polyolefin films, as well as vapor-pervious materials, such as microporous polyolefin films.
The temperature-responsive polymer of the present invention will generally be employed in a disposable absorbent product comprising an absorbent structure. Such an 2~ absorbent structure will generally comprise a fibrous matrix into which an absorbent material such as, for example, a hydrogel-forming polymeric material is dispersed such that the fibrous matrix constrains or entraps the absorbent material.
The fibrous matrix may be formed by air-laying fibers, through a spunbond or meltblown process, a carding process, a wet-laid prucess, or through essentially any other 30 means, known to those skilled in the art, for forming a fibrous matrix.
Methods of incorporating an absorbent material into a fibrous matrix are known to those skilled in the art. Suitable methods include incorporating an absorbent material into the matrix during formation of the matrix, such as by air laying the fibers of the fibrous matrix and the absorbent material at the same time or wet-laying the fibers of the fibrous 3~ matrix and the absorbent material at the same time. Alternatively, it is possible to apply the absorbent material to the fibrous matrix after formation of the fibrous matrix. Other CA 02240~7~ 1998-06-2~
WO 97J2415~ PCT)US96J20420 methods include sandwiching the absorbent material behNeen two sheets of IlldL~ i, at least one of which is fibrous and iiquid permeable. The absorbent material may be generally uniformly located between the two sheets of material or may be located in discrete pockets formed by the two sheets. The absorbent material may be distributed in 5 the individual layers in a generally uniform manner or may be present in the fibrous layers as a layer or other nonuniform distribution.
The fibrous matrix may be in the form of a single, integrally formed layer or of a composite comprising multiple layers. If the fibrous matrix co" ,~,ri ,es multiple layers, the layers are preferably in liquid communication with one another such that a liquid present in 10 one flbrous layer can flow or be transported to the other fibrous layer. For example, the fibrous layers may be separated by cellulosic tissue wrap sheets known to those skilled in the art.
When the fibrous matrix comprises a single, integrally formed layer, the concentration of absorbent material may increase along the thickness of the fibrous matrix 15 in a gradual, nonstepwise fashion or in a more stepwise fashion. Similarly, the density may decrease through the thickness in a nonstepwise manner or in a stepwise manner.
Absorbent structures may generally be of any size or dimension as long as the absu, bent structure exhibits desired absorbent characteristics.
Absorbent structures are generally suited to absorb many liquids, such as water,20 saline, and synthetic urine, and body liquids such as urine, menses, and blood, and are suited for use in disposable absorbent products such as diapers, adult incontinent products, and bed pads; in calarnenial devices such as sanitary napkins, and tampons;
and in other absorbent products such as wipes, bibs, wound dressings, and surgical capes or drapes.
Disposable absorbent products, according to all aspects of the present invention, are generally subjected during use to multiple insults of a body liquid. Accordingly, the disposable absorbent products are desirably capable of absorbing multiple insults of body liquids in quantities to which the absorbent products and structures will be exposed during use. The insults are generally separated from one another by a period of time.
A~ter the disposable absorbent product has been used, it will be desirable to dispose of the disposable absorbent product. If the disposable absorbent product includes the temperature-responsive polymer of the present invention, it may be possible to dispose of t the product directly to a liquid disposal system, such as by disposing of the product into a toilet. When placed into a toilet, an excess of water will generally be present and the 35 temperature of the water will generally be lower than the temperature of the li~uid insulting the product such that the temperature-responsive polymer of the present invention may CA 02240~7~ 1998-06-2~
rapidly disperse into the water. The disposable absorbent product may then be capable of being flushed down the toilet without fear of the disposable absorbent product clogging the piping of the toilet. By this method of disposal, the disposable absorbent product may then be successfully treated and degraded by the sewage system to which the toilet is attached instead of disposing of the disposable absorbent product through a solid waste disposable system. By not having to be disposed of through a solid waste disposable system, the use of the temperature-responsive polymer of the present invention may reduce the amount of solid waste that has to be landfilled, incinerated, or otherwise disposed of.
Test Methods Intrinsic Viscositv Intrinsic viscosity is a parameter which directiy reflects the molecular properties of a dissolved polymer. For a flexible polymer the i, Illil Isic viscosity is related to Ma where M
15 represents the molecular weight of the polymer and 0.50 ~ a < 0.80. Intrinsic viscosity ([tl]) is calculated using the following equations:
(~11]) = lim (1/c) {(~ o3- 1} Equation 1 c~o wherein:
~ = the solution viscosity at a given polymer concentration llo = the solvent viscosity and:
O = t/to Equation 2 wherein:
t = the time for a polymer solution to flow through a viscometer to = the time for a solvent to flow through a viscometer A Canon Fenske viscometer was used to measure the relative viscosity of a polymer solution with respect to viscosity of deionized water, which was used as the solvent.
Viscometer numbers 100 and 150 were used. The flow time for deionized water at room 30 temperature for viscometer number 100 was about 58.5 seconds and that for viscometer number 150 was about 28.5 seconds. Higher viscosity polymer samples, such as poly(N-iospropylacrylamide), were studied using viscometer number 150 and iower viscosity polymer samples were studied using viscometer number 100.
The relative viscosities for a polymer sample were measured at 5 different polymer concentrations. The right hand side of Equation 1 (y-axis) was plotted against polymer CA 02240~7~ l998-06-2 WO 97/24150 PCTJUS96/2~42~
concentration (x-axis). On extrapolation to zero concentration, the intercept on the y-axis yields the intrinsic viscosity for the polymer sample.
Water Solubilitv TemPerature Polymers that are temperature responsive exhibit cloud points wherein the polymer precipitates out of solution on heating the solution above the cloud point. On precipitation the solu$ion turns turbid and the cloud point can be measured. Solutions containing between about 0.2 weight percent to about 1.0 weight percent are used for determining the water solubility temperature for a polymer. The solution was poured into a scintillation 10 vial. A thermometer was dipped into this solution and clamped in position with the help of a laboratory stand. A small magnetic stirrer was used for agitation. The solution in the vial was heated at a temperature increase of about 1~C per minute. The temperature at which the thermometer bulb became invisible due to solution turbidity was recorded as the cloud point.
1~
Pry Tensile Strength Dry tensile strength measurements were performed on a Sintech 1/D tensile testing system. Fiim samples, having a thickness of about 0.002 inch and prepared from apolymer sample, was cut to a width of about 0.75 inch. The distance between the grips of 20 the tensile tester was about 1.5 inch. The stretch rate of the grips was about 3 millimeters per second.
Wet Tensile Strength Wet tensile strength measurements were performed in deionized water using a 25 Vitrodyne V1000 mini-tensile tester with the testing speed of about 3 millimeters per second. The distance between the grips of the tensile tester was about 1.5 inch. Film samples, having a thickness of about 0.002 inch and prepared from a polymer sample, was cut to a width of about 1.0 inch. The wet tensile strength measurements wereperformed in cold water at ambient temperature and in warm water at temperatures about 30 5~C above the water solubility temperature of polymer san"~les. The samples were immersed in water for about 30 seconds before testing in the tensile tester for the binder testing and for about 5 minutes before testing in the tensile tester for the film testing.
CA 02240~7~ 1998-06-2~
Examr les Exam~le 1 To a 0.45 M aqueous solution of N-isopropylacrylamide, available from Eastman Chemical Company, was added 0.4 mole percent potassium persulfate, available from 5 Aldrich Chemical Company, at about room temperature (about 23~C) under a nitrogen atmosphere. The reaction was aliowed to proceed for about 8 hours at about 30~C. The polymer was removed from the reaction mixture by heating the mixture above the cloud point of the polymer so that the polymer could be recovered. The polymer was then washed with warm water and dried under vacuum. The yield of the polymer was about 50 10 percent. The prepared polymer was found to exhibit an intrinsic viscosity of about 437 cubic centimeters per gram. Because of its high intrinsic viscosity, the polymer was not thermally processable.
Exam~le 2 About 22.8 grams (about 0.2 mole) of N-isopropylacrylamide was dissolved in about 200 milliliters of deionized water at about room temperature (about 23~C) under a nitrogen aLI,lospl-ere. The solution was heated to about 55~C and about 0.123 gram (about 0.0004 mole) of potassium persulfate was added to the solution at once. A white precipitate was observed to form immediately in the solution. The reaction was allowed to proceed for 20 about 4 hours at about 55~C. The polymer was then removed from the reaction vessel, washed with warm water, and dried under vacuum at about 50~C to a constant weight.
The yield of the polymer was quantitative. The polymer was placed into water andallowed to stand for about 48 hours at the end of which gel particles of the polymer were still observed. Since the polymer was not completely soluble in water, the polymer was 25 believed to be crosslinked.
Exam~le 3 About 113.1 grams (about 1 mole) of N-isopropylacrylamide was dissolved in a mixture of about 712 milliliters of deionized water and about 38 milliliters of isopropanol 30 (about 5 percent by volume~, available from Mallinchrodt Specialty Chemicals Company, at about room temperature (about 23~C) under a nitrogen atmosphere. The solution was heated to about 52~C and potassium persulfate was added to the solution at once. The solution was observed to become cloudy in a few minutes. The temperature of the mixture increased to about 68~C, believed to be because of the heat generated during the 35 polymerization. The reaction was allowed to proceed for about 4 hours. The polymer was CA 02240~7~ 1998-06-2~
WO 9712d,150 PCT~US96/20420 then removed from the reaction vessel, washed with warm water, and dried under vacuum at about 50OC to a constant weight. The yield of the polymer was quantitative. Th polymer was completely water soluble in water, indicating essentially no .;~ ussl;, Ihi~ ,9 of the polymer. The prepared polymer was found to exhibit an intrinsic viscosity of about 131 cubic centimeters per gram. Fibers with good mechanical strength and clarity were prepared using the polymer in a thermal extrusion process.
Example 4 A process similar to that described in Example 3 was used except that about 10 10 percent by volume of isopropanol was used to prepare the initial mixture with water.
The prepared polymer was found to exhibit an intrinsic viscosity of about 83 cubic centimeters per gram. Fibers with good mechanical strength and clarity were prepared using the polymer in a thermal extrusion process.
15 ExamPle 5 A process similar to that described in Example 3 was used except that about 15 percent by volume of isopropanol was used to prepare the initial mixture with water.
The prepared polymer was found to exhibit an intrinsic viscosity of about 68 cubic centimeters per gram. Fibers with good mechanical strength and clarity were prepared 20 using the polymer in a thermal extrusion process.
F~amPle 6 A process similar to that described in Example 3 was used except that about 20 percent by volume of isopropanol was used to prepare the initial mixture with water.
25 The prepared polymer was found to exhibit an intrinsic viscosity of about ~0 cubic centimeters per gram. Fibers with good mechanical sllenyll, and clarity were prepared using the polymer in a thermal extrusion process.
ExamPle 7 To an about 1 M aqueous solution of N,N-diethylacrylamide was added about 0.2 mole percent potassium persulfate at about room temperature (about 23~C) under a nitrogen atmosphere. The reaction was allowed to proceed for about 24 hours at about 21 .B~C. The polymer was precipitated in warm water, washed with warm water, and dried under vacuum. The prepared polymer was found to exhibit an intrinsic viscosity of about 292 cubic centimeters per gram.
CA 02240~7~ 1998-06-2~
WO 97/24150 PCT/US96/2~)420 ~xam~le 8 About 41.3 grams (about 0.325 mole) of N,N-diethylacrylamide was dissolved in a mixture of about 244 milliliters of deionized water and about 27 milliliters of isopropanol.
5 The solution was purged with nitrogen at about 65~C for about 30 minutes. Potassium persulfate (about 0.18 gram; about 0.00065 mole) was added to the solution at once. The reaction was allowed to proceed for about 3 hours. The polymer was then removed from the reaction vessel, washed with warm water, and dried under vacuum. The prepared polymer was found to exhibit an intrinsic viscosity of about 23 cubic centimeters per gram.
While the invention has been described in detail with respect to speci~lc embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to, variations of, and equivalents to these embodiments. Accordingly, the scope of the present invention 15 should be assessed as that of the appended claims and any equivalents thereto.
Claims (26)
1. A polymeric film comprising a temperature-responsive polymer wherein the temperature-responsive polymer exhibits an intrinsic viscosity less than about 500 cubic centimeters per gram, and the polymeric film exhibits a dry tensile strength of at least about 50 grams of force per 2.54 centimeters of width and a wet tensilestrength that is at least about 2 percent of the dry tensile strength.
2. The polymeric film of Claim 1 wherein the temperature-responsive polymer is selected from the group consisting of poly(N-substituted acrylamides), poly(N-substituted methacrylamides, and copolymers thereof.
3. The polymeric film of Claim 2 wherein the temperature-responsive polymer is selected from the group consisting of poly(N-isopropylacrylamide), poly(N-propylacrylamide), poly(N-ethoxypropylacrylamide), poly(N,N-diethylacrylamide), poly(N-isopropyl methacrylamide), poly(N-ethoxypropyl methacrylamide), and copolymers thereof.
4. The polymeric film of Claim 1 wherein the temperature-responsive polymer exhibits an intrinsic viscosity that is less than about 500 cubic centimeters per gram.
5. The polymeric film of Claim 1 wherein the temperature-responsive polymer exhibits an intrinsic viscosity that is less than about 300 cubic centimeters per gram.
6. The polymeric film of Claim 1 wherein the polymeric film exhibits a dry tensile strength that is at least about 100 grams of force.
7. A disposable absorbent product comprising a liquid-permeable topsheet, a backsheet attached to the topsheet, an absorbent structure positioned between the topsheet and the backsheet, wherein the topsheet comprises a polymeric film comprising a temperature-responsive polymer wherein the temperature-responsive polymer exhibits an intrinsic viscosity less than about 500 cubic centimeters per gram, and the polymeric film exhibits a dry tensile strength of at least about 50 grams of force per 2.54 centimeters of width and a wet tensile strength that is at least about 2 percent of the dry tensile strength.
8. A process for preparing a temperature-responsive polymer, the process comprising forming a mixture comprising water, a chain transfer agent, a monomer capable ofbeing polymerized to prepare a temperature-responsive polymer that is soluble in water below a temperature that is between about 20°C to about 65°C, and a reaction catalyst, wherein the mixture is prepared under conditions effective to polymerize the monomer to form a temperature-responsive polymer that exhibits an intrinsic viscosity that is at least about 50 percent less than an intrinsic viscosity exhibited by an otherwise substantially identical temperature-responsive polymer that is prepared without using the chain transfer agent, wherein the conditions comprise using a temperature that is greater than the water-solubility temperature of the temperature-responsive polymer.
9. The process of Claim 8 wherein the temperature-responsive polymer is soluble in water below a temperature that is between about 20°C to about 35°C.
10. The process of Claim 9 wherein the temperature-responsive polymer is soluble in water below a temperature that is suitably between about 20°C to about 35°C.
11. The process of Claim 8 wherein the temperature-responsive polymer is selected from the group consisting of poly(N-substituted acrylamides), poly(N-substitutedmethacrylamides), and copolymers thereof.
12. The process of Claim 11 wherein the temperature-responsive polymer is selected from the group consisting of poly(N-isoprupylacrylamide), poly(N-propylacrylamide), poly(N-ethoxypropylacrylamide), poly(N,N-diethylacrylamide), poly(N-isopropyl methacrylamide), poly(N-ethoxypropyl methacrylamide), and copolymers thereof.
13. The process of Claim 8 wherein the temperature-responsive polymer exhibits an intrinsic viscosity that is less than about 200 cubic centimeters per gram.
14. The process of Claim 13 wherein the temperature-responsive polymer exhibits an intrinsic viscosity that is less than about 150 cubic centimeters per gram
15. The process of Claim 14 wherein the temperature-responsive polymer exhibits an intrinsic viscosity that is less than about 100 cubic centimeters per gram.
16. The process of Claim 8 wherein the temperature-responsive polymer exhibits an intrinsic viscosity that is less than about 40 percent less than an intrinsic viscosity exhibited by an otherwise substantially identical temperature-responsive polymerthat is prepared without using the chain transfer agent.
17. The process of Claim 8 wherein the chain transfer agent is selected from the group consisting of isopropanol and water-soluble thiols.
18. The process of Claim 17 wherein the chain transfer agent is isopropanol.
19. The process of Claim 18 wherein the reaction mixture has a volume and the chain transfer agent is used in an amount that is within the range of greater than 0 volume percent to about 50 volume percent of the reaction mixture.
20. The process of Claim 8 wherein the reaction mixture has a volume and the chain transfer agent is used in an amount that is within the range of about 1 volume percent to about 40 volume percent of the reaction mixture.
21. The process of Claim 8 wherein the reaction catalyst is potassium persulfate.
22. The process of Claim 8 wherein the reaction catalyst is used in an amount that is within the range of about 0.001 mole percent to about 1 mole percent of the reaction mixture.
23. The process of Claim 8 wherein the temperature-responsive polymer is selected from the group consisting of poly(N-substituted acrylamides), poly(N-substitutedmethacrylamides), and copolymers thereof and exhibits an intrinsic viscosity that is less than about 200 cubic centimeters per gram, the chain transfer agent is selected from the group consisting of isopropanol and water-soluble thiols, and the reaction mixture has a volume and the chain transfer agent is used in an amount that is within the range of greater than 0 volume percent to about 50 volume percent of the reaction mixture.
24. The process of Claim 23 wherein the reaction catalyst is potassium persulfate.
25. A temperature-responsive polymer wherein the temperature-responsive polymer is prepared by a process comprising forming a mixture comprising water, a chain transfer agent, a monomer capable of being polymerized to prepare a temperature-responsive polymer that is soluble in water below a temperature that is between about 20°C to about 65°C, and a reaction catalyst, wherein the mixture is prepared under conditions effective to polymerize the monomer to form a temperature-responsive polymer that exhibits an intrinsic viscosity that is at least about 50 percent less than an intrinsic viscosity exhibited by an otherwise substantially identical temperature-responsive polymer that is prepared without using the chain transfer agent, wherein the conditions comprise using a temperature that is greater than the water-solubility temperature of the temperature-responsive polymer.
26. A disposable absorbent product comprising a liquid-permeable topsheet, a backsheet attached to the topsheet, an absorbent structure positioned between the topsheet and the backsheet, wherein the topsheet comprises a temperature-responsive polymer prepared by a process comprising forming a mixture comprising water, a chain transfer agent, a monomer capable of being polymerized to prepare a temperature-responsive polymer that is soluble in waterbelow a temperature that is between about 20°C to about 65°C, and a reaction catalyst, wherein the mixture is prepared under conditions effective to polymerize the monomer to form a temperature-responsive polymer that exhibits an intrinsic viscosity that is at least about 50 percent less than an intrinsic viscosity exhibited by an otherwise substantially identical temperature-responsive polymer that is prepared without using the chain transfer agent, wherein the conditions comprise using a temperature that is greater than the water-solubility temperature of the temperature-responsive polymer.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US953595P | 1995-12-29 | 1995-12-29 | |
| US953695P | 1995-12-29 | 1995-12-29 | |
| US60/009,536 | 1995-12-29 | ||
| US60/009,535 | 1995-12-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2240575A1 true CA2240575A1 (en) | 1997-07-10 |
Family
ID=26679604
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2240575 Abandoned CA2240575A1 (en) | 1995-12-29 | 1996-12-20 | Temperature-responsive materials |
Country Status (4)
| Country | Link |
|---|---|
| AU (1) | AU1466597A (en) |
| CA (1) | CA2240575A1 (en) |
| CO (1) | CO4560581A1 (en) |
| WO (1) | WO1997024150A1 (en) |
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|---|---|---|---|---|
| US5969052A (en) * | 1996-12-31 | 1999-10-19 | Kimberly Clark Worldwide, Inc. | Temperature sensitive polymers and water-dispersible products containing the polymers |
| US6186991B1 (en) | 1998-06-29 | 2001-02-13 | The Procter & Gamble Company | Disposable article having a responsive system including a mechanical actuator |
| US6149636A (en) * | 1998-06-29 | 2000-11-21 | The Procter & Gamble Company | Disposable article having proactive sensors |
| US7772455B1 (en) | 1997-11-14 | 2010-08-10 | The Procter & Gamble Company | Disposable article providing improved management of bodily exudates |
| US6433244B1 (en) | 1998-06-29 | 2002-08-13 | The Procter & Gamble Company | Disposable treatment article having a responsive system |
| US6372951B1 (en) | 1998-06-29 | 2002-04-16 | The Procter & Gamble Company | Disposable article having sensor to detect impending elimination of bodily waste |
| US6160198A (en) * | 1998-06-29 | 2000-12-12 | The Procter & Gamble Company | Disposable article having a discontinuous responsive system |
| WO2000000082A1 (en) | 1998-06-29 | 2000-01-06 | The Procter & Gamble Company | Disposable article having proactive sensor |
| US6359190B1 (en) | 1998-06-29 | 2002-03-19 | The Procter & Gamble Company | Device for measuring the volume of a body cavity |
| EP1091772B1 (en) | 1998-06-29 | 2003-12-03 | The Procter & Gamble Company | Diaper including feces modification agent |
| US6342037B1 (en) | 1998-06-29 | 2002-01-29 | The Procter & Gamble Company | Device having fecal component sensor |
| AU4850599A (en) | 1998-06-29 | 2000-01-17 | Procter & Gamble Company, The | Disposable absorbent article having a responsive system including an electrical actuator |
| DE10024270A1 (en) * | 2000-05-17 | 2001-11-22 | Creavis Tech & Innovation Gmbh | Antimicrobial polymer production, comprises polymerizing optionally substituted acrylamide monomers, used e.g. for coating medical and hygiene articles |
| WO2008069711A1 (en) | 2006-12-08 | 2008-06-12 | Sca Hygiene Products Ab | An absorbent article containing a breathable material layer |
| US20090324693A1 (en) * | 2008-06-30 | 2009-12-31 | Kimberly-Clark Worldwide, Inc. | Delivery Product for Topical Compositions |
| CN112853739B (en) * | 2021-03-02 | 2022-11-04 | 浙江理工大学 | Preparation method of temperature response type Janus nanofiber dressing |
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|---|---|---|---|---|
| US5300358A (en) * | 1992-11-24 | 1994-04-05 | E. I. Du Pont De Nemours And Co. | Degradable absorbant structures |
| CA2093050A1 (en) * | 1992-12-29 | 1994-06-30 | Kimberly-Clark Worldwide, Inc. | Hydrodisintegratable material and products formed thereby |
| CA2128483C (en) * | 1993-12-16 | 2006-12-12 | Richard Swee-Chye Yeo | Flushable compositions |
-
1996
- 1996-12-20 CA CA 2240575 patent/CA2240575A1/en not_active Abandoned
- 1996-12-20 WO PCT/US1996/020420 patent/WO1997024150A1/en active Application Filing
- 1996-12-20 AU AU14665/97A patent/AU1466597A/en not_active Abandoned
- 1996-12-27 CO CO96067986A patent/CO4560581A1/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| AU1466597A (en) | 1997-07-28 |
| CO4560581A1 (en) | 1998-02-10 |
| WO1997024150A1 (en) | 1997-07-10 |
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