Surgery: splint – brace – or bandage – Bandage structure – Skin laceration or wound cover
Reexamination Certificate
1999-03-05
2001-02-20
Lewis, Kim M. (Department: 3761)
Surgery: splint, brace, or bandage
Bandage structure
Skin laceration or wound cover
C602S041000, C602S042000
Reexamination Certificate
active
06191336
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to adhesive-coated sheet materials, adhesive bandages comprising said adhesive-coated sheet materials, methods for making said sheet materials and methods for making said adhesive bandages. More specifically, the adhesive-coated sheet materials of the invention comprise fabric-film laminates which have been heat sealed in a discontinuous pattern and have had adhesive applied thereto. Even more specifically, the mentioned heat sealing is limited to regions of the sheet material adjacent its periphery. Preferably, the film is water vapor permeable and the fabric is porous so as to permit the relatively unimpeded passage of air and water vapor therethrough. Adhesive bandages according to the invention have improved adhesion to skin.
PRIOR ART
Methods of making vent holes in adhesive bandages in order to allow skin respiration when the adhesive bandages are applied to the skin are well-known. However, skin respiration is reduced in those portions of the bandages which do not have vent holes. Furthermore, such bandages permit an invasion of water through the vent holes, making it difficult for bandage users to conduct daily works such as kitchen work, a bath, etc. while adhering adhesive bandage after it has been contacted by water. Consequently in such cases, users must peel off the adhesive bandage when starting their daily work, and after the work is over a new bandage is applied again. This is laborious and may involve the disposal of still usable bandages. As a measure against these problems, an adhesive bandage comprising a base sheet made of a nonwoven fabric on which a film having water vapor permeability and water proofing property is laminated and an adhesive layer with water vapor permeability has been proposed.
In such an adhesive bandage, water invasion through the surface of the base sheet to a pad covering a wound may be prevented, but water will soak into the pad through a cut section of the nonwoven fiber fabric at the periphery of the bandage. Consequently it is necessary to prevent effectively the water soaking into the pad from the periphery of the bandage. As a measure against this problem, a method of sealing the periphery of the bandage by heating has been proposed in Japanese Laid-open Patent Hei 8-33673. However, even in bandages made by using such method, there is a problem in that the film may peel off the nonwoven fabric.
This invention uses an improved method of heat sealing in order to reduce or eliminate the aforementioned problems. As mentioned above, adhesive bandages in accordance with the invention have improved adhesion to skin.
DETAILED DESCRIPTION OF THE INVENTION
This invention relates to a method of heat sealing an adhesive bandage comprising a base sheet made by laminating a film on a thermoplastic fiber fabric and an adhesive layer set on a surface of the thermoplastic fiber fabric of said base sheet, characterized by said adhesive bandage being pattern-sealed, and more particularly, to a method of heat seal performed under the condition that the film does not melt and preferably only the thermoplastic fiber fabric melts. In the present invention, it is preferred that only the periphery of the adhesive bandage is pattern-sealed. Further it is preferred that the adhesive bandage is a dressing for medical treatment or an adhesive bandage having a pad. More particularly, the present invention relates to a method of heat-sealing an adhesive bandage which comprises laminating a base fabric made of a thermoplastic fiber having gas permeability on a film having water vapor permeability and gas permeability to make a base sheet, and coating an adhesive layer on the surface of the thermoplastic fiber fabric of the base sheet, characterized in that the pattern seal provides said bandage with water proofing property, and it is preferred that the heat seal is performed under the condition that the film does not melt but the thermoplastic fiber fabric melts, in particular, only the periphery of the adhesive bandage is sealed. Further it is preferable that the adhesive bandage has a pad. The present invention further relates to an adhesive bandage which being made by means of the methods described above, particularly an adhesive bandage having a pad which is made by means of the methods described above.
Adhesive bandage refers to a strip of a fabric or the other materials coated uniformly with a pressure-sensitive adhesive on one side of the surface, but an adhesive bandage in the present invention also includes an adhesive bandage having a wound-contacting pad and, further, a dressing for medical treatment to bind up a wound in wide range.
The thermoplastic fiber fabric used in the present invention includes woven fabrics and nonwoven fabrics made of thermoplastic elastomers. The reason the fiber fabric must be made of a thermoplastic elastomer is that the fiber fabric must melt and be pressed by pressure and heat to give the bandage a water-proofing property when heat-sealed. Also such fiber fabric preferably has gas permeability and elasticity.
The thermoplastic elastomer can be, for example, polystyrene type elastomers such as styrene-isoprene-styrene type block copolymer and hydrogenated block copolymers made by hydrogenating said block copolymer, polyurethanes, polyesters, polyolefines such as polyethylene, and mixtures thereof; they are, however, not critical. The fabric of the present invention can be either a woven fabric or a nonwoven fabric, but the nonwoven fabric is preferred because the directional dependency of physical properties such as elasticity is low.
When using a nonwoven fabric as a fiber fabric, the percentage expansion of the nonwoven fabric is preferably 100% or more, and the recovery at 50% expansion is 70% or more.
The weight of the nonwoven fabric of this invention has to be properly selected depending on properties of the nonwoven fabric itself, the laminating film and the adhesive, but cannot particularly be limited. However, the weight is preferably 20 to 200 g/M
2
, more preferably 30 to 100 g/M
2
. A thickness of the nonwoven fabric may be such a thickness that a sufficient stiffness is imparted to the adhesive bandage when laminating a film on the nonwoven fabric. The nonwoven fabric of this invention can be thinner than that of conventional adhesive bandages. The thickness of the nonwoven fabric is about 20 to 1,000 &mgr;m, preferably 50 to 500 &mgr;m. It is preferable to make the film thin so as to ensure high gas permeability and water vapor permeability.
The film to laminate the fiber fabric in this invention is used to impart water proofing property to the adhesive bandage without much decrease in gas permeability and water vapor permeability of the fiber fabric as well as to ensure a suitable balance of properties when an adhesive bandage is made. The material of the film is required to have a water proofing property and to have sufficient water vapor permeability even after being laminated to a fiber fabric. As such films, known films made of polyurethanes, polyvinyl chloride, polyvinylidene chloride, polyolefines such as polyethylene and polypropylene, polyesters, polyamides and so forth can be used. Polyurethane films and polyester films in particular are preferred among them.
As polyester elastomers, for example, polyester elastomer “Hytrel” (Trade Mark of E. I. DUPONT DENEMOUR AND COMPANY), “Fleclone” (Trade Mark of Nichigo Film Kabushiki Kaisha) and so forth are preferred. Since the laminating film must have a sufficient water proofing property, a film obtained by extrusion molding, blow-molding or the like is desirous. A drawn film may also be used. The laminating film can be also a multilayered film formed by laminating films made of different materials.
If the material of the laminating film has a low water vapor permeability, the film has to be thin in order to have the desirable water vapor permeability. If the material of the laminating film has high water vapor permeability, it can be thick, but has to have suitable stiffness when laminated on t
Mashiko Yasushi
Saito Toshikazu
Yoshida Takeshi
LandOfFree
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