Classifications

• • 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
  • A61F13/53—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 absorbing medium
• • 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
• • 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
  • A61F13/53—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 absorbing medium
  • A61F2013/530481—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 absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials
  • A61F2013/530583—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 absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials characterized by the form
  • A61F2013/530649—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 absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials characterized by the form in sponge or foam
• • 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
  • A61F13/53—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 absorbing medium
  • A61F2013/530481—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 absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials
  • A61F2013/5307—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 absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials characterized by the quantity or ratio of superabsorbent material
• • 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
  • A61F13/53—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 absorbing medium
  • A61F2013/530481—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 absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials
  • A61F2013/530708—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 absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials characterized by the absorbency properties
• • 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
  • A61F13/53—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 absorbing medium
  • A61F2013/530481—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 absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials
  • A61F2013/530708—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 absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials characterized by the absorbency properties
  • A61F2013/530737—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 absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials characterized by the absorbency properties by the absorbent capacity
  • A61F2013/530744—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 absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials characterized by the absorbency properties by the absorbent capacity by the absorbency under load

Definitions

• the present invention refers to an absorbent structure in an absorbent article, such as a diaper, sanitary napkin, incontinence guard, wound dressing, bed protection etc., said structure containing a superabsorbent material possibly in combination with other absorbent and/or carrier materials and where the superabsorbent material has a content of renewable and/or biodegradeable raw material of at least 20 % by weight, calculated on the dry weight of superabsorbent material.
• the superabsorbent material can be in particulate form, e g grains, granules, flakes or fibers, or as a film, a foam or a coating on fibers and has a high capability to absorb liquids, such as waer and body liquids, e g urine and blood while swelling and forming a non water-soluble gel.
• So called superabsorbents are crosslinked polymers having the capability to absorb liquid several times, 10 times or more, their own weight. They further have capability to retain liquid even when they are exerted to an external pressure. They are extensively used in hygiene article such as diapers, incontinence guards, sanitary napkins and the like, at which they are usually present in particulate form such as e g grains, granules, flakes or fibers and are mixed or layered with other absorbent material, usually cellulosic fibers.
• Superabsorbents usually are crosslinked polymers of different chemical composition.
• the performance of a certain superabsorbent in an absorbent article depends on many factors, such as where and how the superabsorbent is mixed into the absorbent structure, particle shape, particle size and physical and chemical properties such as absorption capacity, gel strength and liquid retaining capacity.
• Gelblocking can also negaitvely effect the abso ⁇ tion capacity in for example a fibrous structure containing superabsorbents.
• Gelblocking means that superabsorbent particles when wetted forms a gel which blocks the pores in the fibrous structure or between the particles and by that obstructs liquid transport from the wetting area to the rest of the absorbent article and liquid transport to all particles. This involves a poor utilization of the total abso ⁇ tion capacity of the absorbent body and involves a risk for leakage.
• a high gel strength - cross linking of the superabsorbent involves a decreased risk that gelblocking will occur.
• a too high gel strength however results in a too low abso ⁇ tion capacity.
• gel strength is meant the tendency to gel deformation, which can be defined as the shear modulus of the gel. This is measured in a rheometer and is calculated as the relationship between (a) the shear stress/deformation that is applied to the sample and (b) the relative deformation/shear stress showed by the sample.
• the shear modulus, G' is measured in the unit Pa. This is described in e g EP-B-254 476.
• AUL absorbency under load
• FSC free swell capacity
• CRC centrifuge retention capacaity
• the object and most important features of the invention is to provide .an absorbent structure in an absorbent article of the above mentioned kind where the absorbent structure contains a super- absorbent material wholly or partly based on renewable and/or biodegradeable raw materials and which shows a very good performance in the absorbent structure measured as abso ⁇ tion capacity and acquisition rate.
• the superabsorbent material preferably has a phase angle ⁇ ⁇ 6°, preferably ⁇ 4°and most preferably ⁇ 3 ° .
• the superabsorbent material should preferably have a content of renewable and/or biodegradeable raw material of at least 40, preferably at least 60 and most preferably at least 80% by weight, calculated on the dry weight of the superabsorbent material.
• the superabsorbent material comprises a crosslinked polymer, where the polymer is based on renewable and/or biodegradeable raw material and the crosslinking agent either is renewable and/or biodegradeable or non-renewable/ non-biodegradeable.
• the absorbent structure can according to an embodiment contain a combination of hydrophilic fibers and superabsorbent material, at which the hydrophilic fibers preferably are cellulosic fluff pulp, tissue or hydrophilic synthetic fibers, and the absorbent structure contains between 5 and 80 % by weight superabsorbent material calculated on the total weight of the structure.
• the absorbent structure contains a combination of an absorbent foam material and a superabsorbent material.
• the superabsorbent material can have a relatively low abso ⁇ tion capacity under load (AUL), more precisely no more than 25, preferably no more than 20 and most preferably no more than 18 ml of an acqueous solution containing 0,9 % by weigh of sodium chloride, per g superabsorbent material under a load of 2kPa.
• AUL abso ⁇ tion capacity under load
• the absorbent structure according to the invention is intended to be used in an absorbent article of the kind comprising a liquid pervious cover sheet, a liquid impervious bottom sheet and an absorbent structure applied therebetween.
• the absorbent article can be a diaper, a sanitary napkin, an incontinence guard, a wound dressing, a bed protection etc.
• the shape and construction of the absorbent article is of course completely optional and the invention can be applied to all types of such articles.
• the increasing environmental conciousness has however involved that there is an aim towards replacing the materials in absorbent articles, e g diapers, that are based on non- renewable/non-biodegradeable raw materials with materials that are completely or partly based on renewable and/or biodegradeable raw materials.
• the materials concerned are the liquid impervious bottom sheet in the form of a plastic film, the liquid pervious cover sheet in the form of a nonwoven and the superabsorbent.
• AUL can have very different abso ⁇ tion capacity if they are combined with hydrophilic fibers, usually cellulosic fluff pulp, in an absorbent structure.
• hydrophilic fibers usually cellulosic fluff pulp
• the inventors of the present invention have therfore searched for another parameter showing a clear correlation with the abso ⁇ tion capacity of the superabsorbenten when inco ⁇ orated in an absorbent structure, as it is intended to be in an absorbent article, e g a diaper.
• Rheology is the science of the deformation and and flow properties of materials.
• the term rheology includes all deformation of a material that occurs when it is exerted to forces, both the usual gravitation or if higher forces are needed.
• Rheology deals with the relationship between FORCE, DEFORMATION and TIME.
• VISCOUS In the cases where all deformation energy is spread as heat in the material this is denoted as VISCOUS and one says that the material flows. In the cases where all deformation energy is stored in the material the material is denoted as ELASTIC and no flowing ocurs. A material in which a certain part of the deformation energy is stored and a certain part in spread as heat is denoted as VISCOELASTIC.
• VISCOELASTIC A material in which a certain part of the deformation energy is stored and a certain part in spread as heat.
• the phase shift between deformation and strain is called the phase angle ⁇ . This is 0° for an ideally elastic material and 90° for an ideally viscous material.
• modules G ' and G" have the more elastic and viscous respectively the material is. According to the above mentioned EP-B-254476 it is the module G' that is measured, which according to the invention has proved to be insufficient in order to foresee the function of the superabsorbent in an absorbent structure.
• Those superabsorbents having a value of ⁇ ⁇ 8° show an especially good product function in the form of abso ⁇ tion capacity and acquisition rate. It is especially siuprising that this applies also to superabsorbents having such a low AUL value as lOg/g at 2 kPa, which is evident form table 1 below.
• the rheological measurements are made on a Carri Med CSL 2 100 from TA
• the rheometer is a "controlled stress"- instrument.
• the measurment are performed according to established rheological methods, so that the person skilled in the art should easily be able to repeat the measurments.
• the materials are prepared as samples according to the principle: lg absorbent material to 20 g synthetic urine.
• the mixture sample + synthetic urine is allowed to stand for 2 hours before tested, however within 6 hours from the mixture was prepared
• step one includes a so called "stress- sweep" with which the linear area of the material is defined.
• the linear viscoelastic area area occurs when the deformation is so small that the material only neglectably changes from its equilibrium position. From this linear position the shear stress is chosen, at which the material is to be tested in the coming frequency sweep. From the frequency sweep 0,l-10Hz the quantities G', G" and ⁇ are obtained. All G', G" and ⁇ -values shown in the table below are taken at 1,13 Hz.
• the superabsorbent based on renewable raw material that were tested were a number of test substance based on crosslinked CMC (carboxy methyl cellulose): Al, A2, A3, A4, A5, A6, A7, A8, A9, A10, Al 1, A12, A13 och A14.
• Preparation of superabsorbents based on crosslinked CMC is descrubed in e g EP-B-201 895.
• Some test substances based on crosslinked carboxy methyl starch: Bl, B2 och B3, were also tested, and which can be produced analogously with crosslinked carboxy methyl cellulose (CMC).
• CMC carboxy methyl cellulose
• Sanwet IM 7100 which is a crosslinked sodium polyacrylate and pure cellulosic fluff pulp without admixture of superabsorbent.
• the abso ⁇ tion concept tested consisted of 20 % by weight of a superabsorbent mixed with cellulosic fluff pulp of chemical type.
• the basis weight of the pulp structure was 500 g/m 2 .
• the test liquid was in all cases synthetic urine according to the following recipe : 60 mmol KC1 (4.5 g), 130 mmol NaCl (7.6 g), 3.5 mmol MgSO 4 (0.42 g) , 2.0 mmol CaSO 4 *2H 2 0 (0.34 g), 300 mmol urea (18 g) and 1 g 0.1% triton were dissloved in 1 liter destilled water.
• the measuring methods used for testing the function of the superabsorbent in an absorbent structure according to above were the following:
• the absorption capacity in a sloping plane The sample body was placed in a 30° inclination in order to imitate the position of the diaper during use and the lower portion was in contact with a liquid bath (synthetic urine) and was absorbing liquid by suction. The sample body was weighed before and after liquid abso ⁇ tion and the abso ⁇ tion was noted as g absorbed liquid per g absorbent body.
• the superabsorbent was in the form of particles which were mixed with cellulosic fluff pulp for forming an absorbent body.
• the invention is however not limited to such absorbent bodies, but it would also be possible to apply superabsorbent particles in the form of a layer between layers of cellulosic fluff pulp or other optional hydrophilic fibers, natural or synthetic.
• the superabsorbent can also be applied between layers of soft paper (tissue), nonwoven or other material.
• the superabsorbent can also be present in the form of fibers, as a film or as a coating on another material or as a foam.
• the absorbent body can contain other types of hydrophilic fibers, absorbent foam material or the like.

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• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Vascular Medicine (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Epidemiology (AREA)
• Animal Behavior & Ethology (AREA)
• Veterinary Medicine (AREA)
• Absorbent Articles And Supports Therefor (AREA)
• Materials For Medical Uses (AREA)
• Orthopedics, Nursing, And Contraception (AREA)
• Biological Depolymerization Polymers (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)

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Cited By (6)

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Citations (5)

• 1997
  • 1997-12-29 SE SE9704881A patent/SE514710C2/sv not_active IP Right Cessation
• 1998
  • 1998-12-23 AR ARP980106667A patent/AR011490A1/es not_active Application Discontinuation
  • 1998-12-23 GB GB9828577A patent/GB2332629B/en not_active Expired - Fee Related
  • 1998-12-24 PE PE1998001279A patent/PE20000160A1/es not_active Application Discontinuation
  • 1998-12-25 TN TNTNSN98232A patent/TNSN98232A1/fr unknown
  • 1998-12-28 CO CO98076861A patent/CO5070595A1/es unknown
  • 1998-12-28 ZA ZA9811889A patent/ZA9811889B/xx unknown
  • 1998-12-29 JP JP2000526181A patent/JP2001526954A/ja active Pending
  • 1998-12-29 AU AU20829/99A patent/AU2082999A/en not_active Abandoned
  • 1998-12-29 WO PCT/SE1998/002454 patent/WO1999033420A1/en not_active Application Discontinuation
  • 1998-12-29 PL PL98341425A patent/PL341425A1/xx unknown
  • 1998-12-29 CA CA002315748A patent/CA2315748A1/en not_active Abandoned
  • 1998-12-29 SK SK893-2000A patent/SK8932000A3/sk unknown
  • 1998-12-29 EP EP98965355A patent/EP1043965A1/en not_active Withdrawn
  • 1998-12-29 KR KR1020007007230A patent/KR20010033707A/ko not_active Application Discontinuation
• 1999
  • 1999-03-09 TW TW088103585A patent/TW467738B/zh not_active IP Right Cessation
• 2000
  • 2000-06-28 MX MXPA00006408 patent/MXPA00006408A/es not_active IP Right Cessation

Patent Citations (5)

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