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
  • 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
  • A61L15/28—Polysaccharides or their derivatives
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/001—Modification of pulp properties
  • D21C9/002—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives
  • D21C9/004—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives inorganic compounds
• • 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
  • A61F13/534—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 an inhomogeneous composition through the thickness of the pad
  • A61F13/537—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 an inhomogeneous composition through the thickness of the pad characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer
• • 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
  • A61F2013/15406—Basis weight
• • 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
  • A61F2013/15463—Absorbency

Definitions

• This invention relates to absorbent pulps; more specifically this invention relates to wet-laid pulp sheets which are convertible to an end product without the added steps of disintegrating a pulp sheet to make a fluff pulp and then air-laying the pulp to make a sheet that is then cut up into appropriate sizes to obtain the desired product. Still further, this invention relates to the method of preparing a wet laid pulp sheet from cold caustic extracted pulp.
• absorbent devices such as baby diapers, incontinence and catamenial devices and wound dressings, (i.e., absorption intensive devices)
• these products are made by first making a pulp sheet of a dense, board-like nature.
• these sheets are made by wet-laying the pulp and with the aid of vacuum suction, and drying, making a rolled up bale of pulp.
• Such rolled-up bales of pulp are then sent to the customer who disintegrates the stiff, board-like sheet with a special device to make a “fluff” pulp.
• the fluff pulp is then air-laid either directly on an appropriately sized wire screen; or, more typically, the pulp is air-laid on a tissue sheet on a wire and then an air-laid sheet is formed. Subsequently, the air-laid sheet is cut up into the desired product shape such as a baby diaper and like.
• the desired product shape such as a baby diaper and like.
• Pad Integrity is a measure of the strength of an absorbent core. The pad integrity value is measured as the maximum force required to push a 13 ⁇ 4′′ piston through the pad. Normal pad integrity fluff pads have a basis weight of 500 g/m 2 and a density near 0.05 g/cm′′. Samples F-1, J-1 and K-1 had a basis weight comparable to routine Rayfloc-J fluff sheet previously identified above. The novel samples showed an increase in pad integrity of approximately 40%. All the novel samples had higher pad integrity values than routinely measured for Rayfloc-J® fluff. Pad integrity test results are listed in Table I-4.
• GATS Grammetric Absorbency Testing System testing measures the absorbency characteristics of an absorbent core.
• the GATS test was performed with M/K Mark II GATS test equipment. The test measures the quantity of deionized water absorbed into the test sample through a 2 mm diameter hole. The test is controlled so that there is no pressure head on the liquid. When the pad is saturated, it is adjusted so that there is a one inch height differential between the test piece (higher) and the liquid reservoir (lower). This allows loosely retained liquid to drain back into the test reservoir. The retention value is the amount of liquid absorbed after draining is completed. The dry pad height is measured as absorption begins and the wet pad height after draining is completed.
• the GATS test also measures the change in pad height as liquid is being absorbed (Table I-6).
• the novel unpressed sheets maintained approximately 70% of their height, compared to about 45% for conventional fluff pads.
• the pressed sheets swell with absorption and increase about 130% in caliper.
• the acquisition layer test was done with the unfluffed wet laid pulp sheets. This test is also done on absorbent products to evaluate their performance. This test simulates the performance of the sheet as an absorbent core.
• the sample is cut to 7 cm ⁇ 17 cm and placed on a stack of 7 blotter sheets.
• the blotter sheets would simulate a layer of a superabsorbent polymer (SAP) under the pad.
• a piece of non-woven cover stock is placed on top of the sample.
• a 50 ml “insult” of synthetic urine is introduced to the pad via 2′′ diameter tube centered over the sample. The time for the synthetic urine to completely penetrate the cover stock is recorded.
• a stack of five blotter sheets is placed on the sample 90 seconds after the synthetic urine is absorbed.
• a weight applying 1 psi of pressure to the sample is placed on the blotter stock. After 120 seconds the weight and blotter sheets are removed. The amount of synthetic urine absorbed by the blotter sheets is the rewet value.
• CCE cold caustic extracted
• Ethenier-F-UHV® Ultrahigh Viscosity Sulfite Southern Pine pulp produced by Rayonier Inc. wet laid pulp sheets were tested in a manner similar to Example I for use as an absorbent core without fluffing.
• the first series was treated with an 18% cold caustic extraction (CCE) and the second was treated with a 15% CCE.
• Each series contained samples at 650 g/m 2 (basis weight) that were conventionally pressed, and 1000 g/m 2 and 500 g/m 2 sheets that were not pressed. Some of the unpressed sheets were air dried and others were dried in a tunnel drier.
• Table II-1 summarizes the properties of the wet laid sheets. Density and caliper results are listed in Table II-2. The density was not affected by the type of drying or by changes in the basis weight. It appears that the density is primarily a function of the pressing. These results are similar to those observed with Porosanier-J-HP® (mercerized kraft Southern Pine pulp produced by Rayonier Inc.).
• Pad integrity test results are listed in Table II-3.
• Pad integrity is a measure of the strength of an absorbent core.
• Normal pad integrity fluff pads have a basis weight of 500 g/m 2 and a density near 0.05 g/cm 3 .
• CCE samples at a basis weight comparable to Rayfloc-J® fluff showed an increase in pad integrity of approximately 6%.
• the CCE samples were slightly higher in density than Rayfloc-J®.
• Pad integrity for the CCE wet laid sheets appears to be proportional to the basis weight, as the higher basis weight sheets were higher in pad integrity. Pressed sheets had greater pad integrity values.
• GATS Grammetric Absorbency Testing System testing measures the absorbency characteristics of an absorbent core. GATS test results are shown in Tables II-4 and II-5. Each sample was cut to a square weighing 1 gram (fluff samples are prepared in a 2-inch diameter cylinder and weigh 1 gram). The steady state absorption rates of the unpressed wet-laid sheets were greater than what was observed for Porosanier-J-HP® and Rayfloc-J®. All the wet-laid sheets reached their absorption capacity in about 20 seconds. This is approximately twice as fast as fluffed pads. The retention for the unpressed sheets was approximately 60% of that of fluffed pads. The pressed sheets had even lower liquid retention.
• the GATS test also measures the change in pad height as liquid is being absorbed. The results are shown in Table II-5.
• the unpressed sheets maintained approximately 70% of their height, compared to about 45% for fluff pads. Because the unpressed sheets have less wet collapse, their absorption rate is higher than regular fluff pads. The pressed sheets swell with absorption and increase in caliper about 170%.
• Unpressed CCE Ethenier-F-HV® (a sulfite chemical Southern Pine pulp produced by Rayonier Inc.) pulpsheets according to the invention exhibit excellent absorption and pad integrity. Their performance is equivalent to diapers without a special acquisition layer fiber. There also appears to be less wet pad collapse in the wet-laid pulp sheets compared to fluff pads.
• TABLE II-1 WET LAID PULPSHEET PROPERTIES CAUSTIC BASIS SAMPLE TREATMENT WEIGHT DRYING NO.
• a composite of CCE pulp and conventional fluff pulp is formed by mixing the pulps in a 50/50 CCE to conventional pulp ratio.
• the resultant composite would exhibit properties approximate to the average of the properties for the individual CCE and conventional pulps. For example, the values for absorption rate, absorption time and liquid retention of the composite pulp would be expected to be between the corresponding values for the individual pulp materials. Intermediate results would be achieved with a mixture of CCE pulp with amount of CCE pulp being as low as 10% by weight. Such composites would be useful for designing materials with specific properties for use in adsorptive devices.
• the method as described herein and the products obtained accordingly have substantial advantages over the conventionally produced products, i.e., products obtained by disintegration (fluffing) and air-laying the fluffed pulp.
• the strength of the material measured in terms of pad integrity, is at least equal to and often exceeds that of conventionally produced products of the same basis weight. As the pad integrity is often improved, the present product is stronger despite its softness.
• the disclosed method Based on the extensive data concerning absorption rates and absorption capacity, the disclosed method produces pulps for the disclosed devices of much improved properties with absorption rates that have been improved from about 37% to 98% based on comparable conventionally produced product.

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• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Veterinary Medicine (AREA)
• Public Health (AREA)
• General Health & Medical Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• Epidemiology (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Vascular Medicine (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Wood Science & Technology (AREA)
• General Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Hematology (AREA)
• Materials Engineering (AREA)
• Absorbent Articles And Supports Therefor (AREA)
• Paper (AREA)

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Cited By (6)

Citations (40)

• 1996
  • 1996-07-16 WO PCT/US1996/011774 patent/WO1997004162A2/fr not_active Ceased
• 2002
  • 2002-05-28 US US10/156,256 patent/US20030070776A1/en not_active Abandoned

Patent Citations (43)

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