Stock material or miscellaneous articles – Composite – Of polyamidoester
Reexamination Certificate
1999-12-07
2002-04-02
Tarazano, D.. Lawrence (Department: 1773)
Stock material or miscellaneous articles
Composite
Of polyamidoester
C428S423900, C428S424200, C428S424800, C428S409000, C428S500000, C428S515000, C428S516000, C428S517000, C428S520000, C428S522000, C002S161700, C002S168000, C128S918000, C604S168010, C604S349000
Reexamination Certificate
active
06365278
ABSTRACT:
The present invention relates to multilayer elastomer films (multilayer material) comprising at least one continuous layer carrying active chemical substance (such as corrosion inhibitors, lubricants or alternatively biocides with a medical use) inserted between inert elastomer barrier layers; it also relates to the processes for the preparation and to the various applications of these films.
The various elastomer materials commonly used in the medical or paramedical field can be modified so as to be combined with active chemical substances having a protective effect during the use of these materials (gloves, fingerstalls, condoms, and the like), as illustrated in European Patent 306,389 or International Application WO 95/17453, on behalf of the Applicant Company, which describe elastomer films enclosing a dispersion of at least one active chemical substance, which dispersion being either in the liquid form (International Application WO 95/17453) or contained in microcapsules, the walls of which are ruptured under the effect of frictional or shear forces (European Patent 306,389).
However, the preparation of elastomer films according to the methods described in the above-mentioned applications and patents exhibits a number of disadvantages, which relate either to the product itself, that is to say the film, or to the process for obtaining the film.
disadvantages related to the product:
the major disadvantage of the films according to either of the two abovementioned methods is the non-homogeneity of the distribution of the active chemical substances within the polymeric material, due to the fact that the chemical substance is dispersed in the polymeric material in the form of droplets or microcapsules.
This non-uniformity in the distribution of the active chemical substances is reflected by gaps in active chemical substance, which constitute a risk in the context of the desired protection, even if this risk is statistically very low;
the microcapsules contained in the elastomer films according to European Patent 306,389 can exhibit difficulties in rupturing, to release their active substances, during the perforation of the said films;
the elastomer films containing liquid inclusions according to International Application WO 95/17453 involve macromolecular stabilizers of grafted or sequenced copolymer (block copolymer) type which are relatively expensive.
disadvantages related to the process:
in the case of International Application WO 95/17453, the preparation of films from a dispersion of active chemical substance is conditioned by the stability of the bath containing the dispersion, itself a function of the active substance (virucide, for example) content, which constitutes a limiting factor;
likewise, in U.S. Pat. No. 306,389, the production of microcapsules, of controlled size, requires the use of a complex process, particularly as regards controlling the thickness and porosity of the wall;
the preparation of films according to either of the two methods is accompanied, in all cases, by emission of organic vapours; indeed, the elastomers are always used in more or less concentrated solution form in organic solvents.
Consequently, on continuing its research, the Applicant Company has set itself the aim of developing a new type of elastomer material corresponding better to practical requirements than the array of elastomers of the prior art, in particular in that it includes at least one active chemical substance, in the desired proportions, in the form of a continuous layer and not of a dispersion or of an emulsion, which makes it possible to avoid the problems related to the dispersion and/or emulsification stage (stability of the emulsion bath, expense of the stabilizing polymers, presence of gaps), and in that it makes it possible to obtain a flexible and elastic multilayer material which is particularly well suited to the preparation of gloves, fingerstalls or condoms from which the active substance x is only released in the event of the material tearing.
Moreover, the process for the preparation of the material according to the present invention can be carried out entirely or partially in aqueous medium.
The subject of the present invention is a multilayer polymeric film (multilayer material), characterized in that it comprises at least one layer A composed of a gel which is reversible or non-reversible, as a function of the temperature, and which carries at least one active chemical substance x, and at least two barrier layers E comprising a synthetic elastomer e, the said layers being held together by a polymeric bonding agent y incorporated in at least one of the said layers A or E and/or by an independent bonding layer Z comprising a polymer z and/or by chemical or physical treatment of at least one of the said layers A or E.
Chemical treatment is understood to mean either a grafting or a chemical attack using an acid, for example sulfuric acid, and physical treatment is understood to mean a bombardment of the surface of the film with ions or electrons: corona or plasma treatment, or photons: ultraviolet treatment.
Gels which are non-reversible, as a function of the temperature, are formed chemically, that is to say by crosslinking by covalent bonding, which takes place by addition of a crosslinking agent ic (irreversible crosslinking agent) and/or by thermal or photochemical activation, such as, for example, under the effect of ultraviolet radiation, whereas gels which are reversible as a function of the temperature are formed either physically, that is to say by interaction of hydrogen bond, Van der Waals or dipole-dipole type or by formation of crystalline domains or complexes. Such reversible gels can also, in certain cases, involve a crosslinking agent rc (reversible crosslinking agent).
In the case of reversible gels, a transition takes place at a critical temperature (Ttrans) at which the physical interactions disappear; the gel-liquid transformation corresponds to this temperature.
According to an advantageous embodiment of the said layer A, when it is composed of a reversible gel, the latter essentially comprises a structuring polymer c, at least one active chemical substance x and a solvent s
a
; in addition, it can contain a bonding agent y and a reversible crosslinking agent rc. The combination forms a flexible and elastic layer A.
In certain cases, the structuring polymer c also acts as solvent s
a
.
According to an advantageous arrangement of this embodiment, the said reversible gel exhibits a gel-liquid transition temperature (Ttrans) of between 0° C. and 120° C., preferably of between 20° C. and 85° C. and more particularly between 20° C. and 700° C.
According to another advantageous arrangement of this embodiment, the structuring polymer c of the layer A is a polymer which is immiscible with the elastomer e, preferably of hydrophilic type and compatible with the active chemical substance, alone or in solution in a solvent s
a
.
According to an advantageous form of this arrangement, the structuring polymer c is selected from the group consisting of synthetic polymers of acrylic or vinyl type, such as poly(acrylic acid) and polyvinyl alcohol, or of natural origin, such as gelatin, gums, pectin, alginates, polypeptides, polyureas, heparinoids and poly(gluconic acid), as well as certain cellulose derivatives, such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and carboxymethyl cellulose, or certain starch derivatives and crystallizable or partially crystallizable polymers, such as, for example, polyethers.
According to another advantageous arrangement of this embodiment, the crosslinking agent rc is selected from the group consisting of (i) certain boron derivatives, such as boric acid or borax, (ii) certain divalent metals, such as zinc or calcium, and (iii) certain trivalent metals, such as aluminium, in alumina hydrate, aluminium sulphate or certain aluminium hydroxides, or chromium, in chromium oxide; it is used as crosslinking agent for the structuring polymer c preferably containing hydroxyl functional groups, such as polyv
Busnel Rene Guy
Cheymol Andre
Hoerner Pierre
Riess Gerard
Hutchinson
Morrison & Foerster / LLP
Tarazano D.. Lawrence
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