Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Coated or impregnated woven – knit – or nonwoven fabric which... – Coating or impregnation intended to function as an adhesive...
Reexamination Certificate
2002-06-03
2004-11-02
Zirker, Daniel (Department: 1771)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Coated or impregnated woven, knit, or nonwoven fabric which...
Coating or impregnation intended to function as an adhesive...
C442S150000, C428S343000, C428S3550BL, C525S098000
Reexamination Certificate
active
06812170
ABSTRACT:
The invention relates to a backing material coated on at least one side with a latex-free, cohesive adhesive—i.e., cold seal—composition for medical uses as for example bandages, dressings or dressing materials, in which the individual plies or turns of the dressing stick reliably only to themselves, with little or no sticking to other substrates, particularly the skin, hair or clothes.
Backing materials for medical use with a cohesive coating are known; they are available commercially under the name Elohaft® or Gazofix® from Beiersdorf. These products are normally made using a cold seal composition based on natural rubber.
For certain medical indications, sticking to the skin is not a necessity. In such cases it is advantageous if the product sticks only to itself and not to the skin, hair or clothing. These product properties promote painless, residueless removal of the bandage.
A disadvantage with these products, besides the limited light, temperature, and aging stability, is the presence of proteins and peptides, which can in some cases lead to allergies. Moreover, these systems are not processed as 100% systems, and it is therefore necessary to remove auxiliaries from the cold seal composition after it has been applied to the backing. Systems without a carrier matrix—that is, systems without common organic or inorganic solvents or dispersion media—are referred to as 100% systems. They are processed in the elastic or thermoplastic state. One common mode of processing is that of the melt.
DE U 86 24 190 describes a cohesive dressing material consisting of a backing material and a coating based on an acrylic resin dispersion. Disadvantageous features of this system include the poor shear properties and the removal of the auxiliary on application.
DE A 688 430 discloses a bandage which is impregnated with natural latex and undergoes an aftertreatment with acetic acid. Bandages of this kind, however, are disadvantageous in terms of their flexibility and textile resemblance. Further, this process is not advantageous owing to the additional workstep of aftertreatment.
U.S. Pat. No. 2,238,878 describes a dressing which is coated with a natural latex.
U.S. Pat. No. 3,575,782 discloses a method of producing elastic covering materials comprising nonwoven fibrous webs and highly elastic rubber or polyurethane yarns. The binders of the nonwoven material that are used give it a pressure-sensitively adhesive quality.
EP 0 885 942 A1 discloses an adhesive composition which has a high UV stability. For the blend, block copolymers based on SEPS diblock copolymers and SEBS triblock copolymers may be used. A cold seal composition is not described. The values for bond strength to skin and to the backing material, and the tack, show that cold seal adhesion is not achieved.
EP 0 443 263 discloses an adhesive composition possessing low tack. No description is given of its use for medical products.
A further adhesive dressing is described in DE-A 29 12 129, and is produced by ultrafine distribution of a rubber dispersion.
U.S. Pat. No. 5,692,937 describes a stretchable cohesive bandage coated with a polyurethane dispersion.
DE 196 31 422 discloses a backing material with a self-adhesive coating on at least one side, the self-adhesive composition being a pressure-sensitive hotmelt composition which at a frequency of 0.1 rad/s has a dynamic-complex glass transition temperature of less than −3° C., preferably from −6° C. to −30° C., with very particular preference from −9°C. to −25° C. According to the disclosure therein, the ratio of the loss modulus (viscous component) to the storage modulus (elastic component) of the pressure-sensitive hotmelt composition, at a frequency of 100 rad/s and 25° C., is greater than 0.7. With further preference, the ratio of the loss modulus (viscous component) to the storage modulus (elastic component) of the pressure-sensitive hotmelt composition, at a frequency of 0.1 rad/s and 25° C., is less than 0.40. Backings coated with an adhesive composition of this kind, however, do not exhibit cohesive properties. Instead, very high bond strengths are to be set when the bandage is bonded to the skin.
It is an object of the invention to produce a pressure-sensitively adhesively coated backing material which in particular is free from latex and natural rubber, which sticks only to itself, and which may be removed without residue from the skin.
The invention accordingly provides a backing material for medical use with a pressure-sensitively adhesive coating on at least one side, having an ultimate tensile stress strength of at least 800 cN/cm and a bond strength to the reverse of the backing of not less than 10 cN/cm, the latex-free, cold seal composition applied to the backing material
comprising one or more block copolymers having a styrene content of less than 65% by weight and
having a tan &dgr; of less than 0.4 at a temperature of 25° C. and a frequency of 100 rad/s.
The high shear strength of the cold seal composition is achieved through the cohesive nature of the polymer.
The cold seal composition is preferably a hotmelt cold seal composition, which if desired may have been doped. The softening point of the hotmelt cold seal composition is higher than 50° C., since the coat application temperature is generally at least 70° C., preferably between 90° C. and 190° C., with very particular preference from 75° C. to 140° C. If desired, a postcrosslinking by means of UV or electron beam irradiation may be appropriate, depending on the specific structure of the parent polymer or its additives.
For systems which stick with particular strength, the cold seal composition is based preferably on A-B or A-B-A block copolymers or mixtures thereof. The hard phase A is principally polystyrene or its derivatives and the soft phase B is ethylene, propylene, butylene, butadiene, isoprene or mixtures thereof, with particular preference ethylene, propylene and butylene or mixtures thereof.
The chain of phase B may also include sections of a different kind, such as isoprene, butadiene or similar substances, for example. It is also possible for polystyrene blocks to be present in the soft phase B, in amounts of up to 20% by weight. The overall styrene content is always lower than 65% by weight, preferably less than 40% by weight, with particular preference from 3 to 35% by weight. Preference is given to styrene contents of between 3% by weight and 35% by weight, since a lower styrene content makes the cold seal composition more conforming.
The sum of the weight fractions of the block copolymers in the cold seal composition is preferably more than 20% by weight, more preferably more than 30% by weight, with particular preference from 30 to 70% by weight, and most preferably from 50 to 70% by weight. The controlled blending of diblock and triblock copolymers is especially advantageous, preference being given to a diblock copolymer content of less than 80% by weight.
Very particularly, the blend of block copolymers based on SEPS and SEBS is notable for its diverse possibilities for variation. Particular variations of the two polymer types are advantageous in a ratio of from 1:100 to 100:1, preferably from 1:10 to 10:1, with particular preference from 1:3 to 3:1. By way of example, different A/B diblock copolymers of the SEBS may be combined with different A/B/A triblock copolymers of the SEPS. A combination of different A/B diblock copolymers of the SEPS with different A/B/A triblock copolymers of the SEBS is likewise possible. Also possible, furthermore, is the combination of different A/B/A triblock copolymers of the SEPS with different A/B/A triblock copolymers of the SEBS. For some applications, advantages have been found from compounding A/B diblock copolymers of SEBS and of SEPS. In a first advantageous embodiment, the cold seal composition comprises one or more A/B diblock copolymer types based on SEPS and at least one A/B/A triblock copolymer type based on SEBS. In a further advantageous embodiment, the cold seal composition comprises one or more A/B diblo
Himmelsbach Peter
Kummer Andreas B.
Meyer-Ingold Wolfgang
Beiersdorf AG
Norris & McLaughlin & Marcus
Zirker Daniel
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