Stock material or miscellaneous articles – Structurally defined web or sheet – Edge feature
Reexamination Certificate
2000-08-23
2004-01-06
Cole, Elizabeth M. (Department: 1771)
Stock material or miscellaneous articles
Structurally defined web or sheet
Edge feature
C428S197000, C442S101000, C002S239000
Reexamination Certificate
active
06673421
ABSTRACT:
The invention relates to a stocking having a seamlessly attached antislip or nonslip coating in the edge region of the upper opening of the stocking, especially an antithrombosis stocking.
Medical stockings are known. Owing to their compressive properties, they improve the rate of flow through the veins. For immobilized patients, stockings are used prophylactically to prevent embolisms or thromboses.
Antislip or nonslip treatments for such stockings are likewise known. In particular, antislip coatings are described for the sole region or the edge region at the opening of the stocking.
In the prior art, these coatings are based on natural and synthetic polymers. In particular, the use of amide, silicone, acrylate, vinyl and styrene compounds, and of rubber and latex as well, is known.
A first disadvantage of these compounds is the low washing resistance at relatively high temperatures or the limited adhesion to the stocking. Secondly, chemically reactive compounds are difficult to prepare or are objectionable in terms of their compatibility, especially in contact with the skin. Furthermore, wash-resistant coatings are hard and fairly unconforming.
Current products on the stockings market include an antislip edge at the upper opening of the stocking, which has been applied separately, often by sewing.
This is disadvantageous not only in terms of costs but also as regards handling in the manufacturing process. Advantages, however, include the flexibility in product design, and the strength of the combined unit. Moreover, this edge, which generally comprises a different material, protects the stocking edge against turning over.
U.S. Pat. No. 3,983,870 discloses a slip-resistant support for limbs, especially a medical stocking. The nonslip coating is produced using, inter alia, acrylates and rubbers. In a further listing of substances, without any indication of a possible teaching, undifferentiated mention is made of thermosetting urethanes, whereas crosslinked oligomeric diols are not disclosed.
A sewn-on grip edge is described in the disclosure.
DE 25 05 923 shows a stocking for medical applications, the antislip strip present on the stocking having been fastened with a Merrow seam.
U.S. Pat. No. 5,412,957 discloses an antislip feature in the sole area of the medical stocking. The required flexural stiffness is not described.
FR 2 609 889 describes a special pattern for an antislip ribbon. There is no description of seamless attachment of an antislip ribbon.
DE 39 16 040 describes a method of applying antislip compositions to articles of clothing, in which the articles of clothing are turned inside out. Subsequently, they are caused to rotate about their longitudinal axis. In this case, reactive silicone rubbers, in particular, are used to form the antislip compositions. Owing to the reactivity the process is very complex, since silicones require curing.
U.S. Pat. No. 3,728,875 describes a stocking having a soft inner portion, where an elastic tape based on urethane is sewn on. The teaching does not disclose whether the compounds in question are crosslinked oligomeric diols. Moreover, the attachment of such a tape is expensive, making it disadvantageous as compared with simple treatment by coating. Likewise, a high flexural stiffness is not described.
WO 97/45081 discloses a stocking for medical purposes, having a special polyurethane thread for generating compression. In addition, a strip is attached on the ankle region. Not shown, in contrast, is the seamless attachment of the strip.
The object of the invention is to provide a stocking which features an antislip coating, is suitable for medical requirements, and does not have the disadvantages known from the prior art.
This object is achieved by means of a stocking as specified in the main claim. The subsidiary claims embrace advantageous variants of the subject-matter of the invention.
The invention accordingly provides a stocking having a seamlessly attached antislip or nonslip coating in the edge region of the upper opening of the stocking, the edge of the stocking producing a compressive pressure of from 3 to 45 mm Hg at an extension of from 10% to 350% and having a width-based flexural stiffness (DIN 53121) of at least 20 cN×mm. Furthermore, in the region of the stocking opening, the bond strength of the coating to the stocking is at least 3 N/cm.
The coating preferably comprises a polyadduct having a phase 1 and a phase 2, the mass fraction of phase 1 being greater than 60% by weight.
Phase 1 is a polyadduct of at least one starting material E1 and at least one starting material E3, starting material E1 comprising an oligomeric diol which has a hydroxyl number of more than 20 mg KOH/g (diol) and starting material E3 comprising a silicone-free, at least bifunctional reactive starting material having a molecular weight of less than 300 g/mol.
Phase 2 is a polyadduct comprising at least one starting material E2 and at least one starting material E3, the starting material E2 having, at least in part, terminal functional groups.
The coating features a molar ratio between the starting materials E3 to be crosslinked and the sum of one or more oligomeric diols (starting material E1) and the fraction of further starting materials E2 of from 0.9 to 1.1.
According to Römpp (Römpp Lexikon Chemie—Version 1.5, Stuttgart/New York: Georg Thieme Verlag 1998) the hydroxyl number describes an index which indicates how many milligrams of potassium hydroxide are equivalent to the amount of acetic acid bound by 1 g of substance in the course of acetylation. The sample is generally boiled with acetic anhydride-pyridine and the acid formed is titrated with KOH solution. The hydroxyl number, which is used to assess reactive resins, waxes, fats, oils, solvents, etc., is related—in Anglo-American investigations, identical—to the acetyl number. Further details may be found in the DIN Standards 53 240 (12/1971) and 53 240-2 (12/1993).
In one preferred embodiment, the ratio of the mass fraction of phase 1 and phase 2 is greater than 1.5. In other advantageous embodiments it is between 1.8 and 100, with particular advantage from 2.0 to 20. More preferably, the mass fraction of phase 1 is between 67% by weight and 98% by weight. Particularly advantageous polyadducts have a weight fraction of from 75% by weight to 95% by weight in phase 1, with particular suitability from 76% by weight to 95% by weight.
A modified functional antislip coating is achieved by the foaming thereof.
The antislip substances to be used are in this case foamed preferably using inert gases such as nitrogen, carbon dioxide, noble gases, hydrocarbons or air, or mixtures thereof. In many cases, foaming additionally by the thermal decomposition of gas-evolving substances such as azo, carbonate and hydrazide compounds has proved to be suitable.
The degree of foaming, i.e. the gas fraction, should be at least approximately 5% by volume and may extend up to approximately 85% by volume. In practice, values of from 10% by volume to 75% by volume, preferably from 20 to 60% by volume, with particular preference from 40 to 60% by volume, have been found to be good. If foaming is carried out at relatively high temperatures of from approximately 100° C. to 240° C. with a comparatively high internal pressure, it is possible for very open-pored antislip foam layers to be obtained, which are particularly permeable to air and water vapour. The advantageous properties of the foamed coating are its good conformity even to uneven surfaces, by virtue of the elasticity and plasticity of the foamed device.
A particularly suitable process for preparing the antislip coating foamed in accordance with the invention operates in accordance with the foam mix system. Here, the thermoplastic antislip composition is reacted under high pressure at a temperature above the softening point (approximately 180° C.) with the intended gases such as, for example, nitrogen, air or carbon dioxide in different volume proportions (from about 10% by volume to 80% by volume) in a stator/rotor system.
While the gas entry p
Andrews Arthur-Hugh
Bodenschatz Stefan
Himmelsbach Peter
Beiersdorf AG
Cole Elizabeth M.
Norris McLaughlin & Marcus P.A.
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