FR3039409A1 - DRESSING COMPRISING A SUPPORT AND A HYDROPHOBIC ELASTOMERIC MATRIX - Google Patents

Abstract

The present invention relates to a new dressing comprising a support and a hydrophobic elastomeric matrix coating said support, said matrix comprising an elastomer of SEPS, SEBS or SEEPS type, consisting of a combination of polystyrene blocks and polyolefin blocks, said elastomer having a weight molecular weight less than or equal to 290,000 Dalton measured by gel permeation chromatography, the total elastomer fraction being strictly less than 3.0% of the total weight of said elastomeric matrix.

Description

DRESSING COMPRISING A SUPPORT AND A HYDROPHOBIC ELASTOMERIC MATRIX

The present invention relates to a new dressing comprising a support and a hydrophobic elastomeric matrix coating said support, said matrix comprising an elastomer of SEPS, SEBS or SEEPS type, consisting of a combination of polystyrene blocks and polyolefin blocks, said elastomer having a molecular weight less than or equal to 290,000 Dalton measured by gel permeation chromatography, the total elastomer fraction being strictly less than 3.0% of the total weight of said elastomeric matrix. In particular, the invention relates to a dressing comprising a support and a matrix based on an elastomeric polymer, which matrix constitutes a contact layer with the wound.

Fat-containing dressings have been successfully used for years for the local treatment of traumatic wounds such as cuts or abrasions and chronic wounds such as pressure ulcers, varicose ulcers, or burns in humans. 'animal.

A tulle impregnated with a fat marketed under the name Lomatuell H, by the company Lohmann & Rauscher is one of the products used for the medical care of skin wounds. This product, which is formed of a large mesh cotton fabric impregnated with a fatty substance based on petroleum jelly, has the drawback of releasing too much fat, thus making the product little or not cohesive.

Indeed, during the contact with the wound, vaseline softens due to the temperature increase and tends to be pushed to the periphery of the dressing.

This phenomenon frequently results in exposure of the support and direct contact with the wound. The adhesion of the support to the wound often results in traumatic (bleeding) dressing changes, painful, and discomfort in the healing process. Other commercially available products, for example the bandage of Johnson & Johnson ADAPTIC, which is a viscose knit impregnated with an oil-in-water emulsion or the product JELONET brand (Smith & Nephew Company) which is a paraffin-soaked cotton gauze, have the same objective as the Lomatuell H product. but also present an unfavorable behavior with regard to the loss of fatty substances, and therefore the cohesion of the dressing as a whole.

During the management of a wound, and more particularly of a wound resulting from an ulcer, the peri-lesional skin has a whitish appearance between the first and the fiftieth day after the start of the treatment, in particular because of the that exudate flows from the wound are poorly controlled. However, this peri-lesional skin needs to be taken care of just like the wound itself. It is therefore essential to affix on the wound and its periphery a dressing combining both oil exudation properties sufficient to allow good protection of the peri-lesional skin, but also cohesive properties to avoid the exposure of the support and consequently the direct contact of the latter with the wound, which can lead to a traumatic removal of the dressing which would then hinder the good progress of healing by tearing granulation buds.

It is important to note that successful completion of a dressing comprising a carrier coated with a hydrophobic elastomeric matrix whose oil release levels would be higher than the interface dressings marketed and currently known and which would also maintain a good level of cohesion invoice is a complex process, the conciliation of these two types of antinomic properties within the same product appearing delicate.

The Lohmann & Rauscher EP 2,524,706 describes in particular in its example 1, a nonabsorbent hydrophobic elastomeric matrix intended to come into contact with the wound. This matrix has a total elastomer share relative to the total weight of the matrix of 2.6%. The elastomer chosen in this example is a Septon 4055® SEEPS triblock elastomer and having a molecular weight ranging from 308 to 310 kDalton measured by gel permeation chromatography. However, such a product suffers from certain limitations. Indeed, this product and more specifically the elastomeric matrix constituting part of it does not release a sufficiently large amount of oil, making it not optimal for a sufficiently protective and tolerable application for peri-lesional skin.

In parallel, the patent of the company Urgo Laboratories EP 1 272 229 describes an interface dressing comprising an elastomeric mass consisting of 3 to 8% relative to the total weight of the matrix of a Kraton G® 1651 brand elastomer having a molecular weight. 240,000 daltons measured by gel permeation chromatography. This product, although cohesive, has a level of oil release that needs to be further improved in order to optimally optimize the protection of the peri-lesional skin and the tolerance of this dressing by the latter. Thus, quite surprisingly, a new interface dressing has been developed which combines optimum oil release and cohesion properties, making the latter particularly suitable for efficient wound application. also at the level of the perilesional skin circumscribing it.

Thus, the object of the present invention resides in a dressing comprising a support and a hydrophobic elastomeric matrix coating said support, said matrix comprising an elastomer of SEPS, SEBS or SEEPS type, consisting of a combination of polystyrene blocks and polyolefin blocks, said elastomer having a molecular weight less than or equal to 290,000 Dalton measured by gel permeation chromatography, the total elastomer fraction being strictly less than 3.0% of the total weight of said elastomeric matrix.

Elastomeric matrix

To obtain a hydrophobic elastomeric matrix according to the invention, a triblock elastomer of the polystyrene-b-poly (ethylene-butylene) -fa- polystyrene (S-EB-S) or polystyrene-b-poly (ethylene-propylene) type is used. ) -b-polystyrene (S-EP-S), or polystyrene-b-poly (ethylene-ethylene / propylene) -b-polystyrene (S-EEP-S) with a molecular weight less than or equal to 290000 Dalton.

In the present description, the term "molecular weight" refers to the weight average molecular weight.

The weight average molecular weight of each elastomer (Mw) is determined according to the same method as that disclosed in patent EP 0 640 115. Thus, this determination is made by gel permeation chromatography (GPC) under the following conditions:

- Solvent: THF for HPLC - Flow rate: 1.33 ml / min - Temperature: Ambient - Volume injected: 200 microliters - Sample concentration: 0.05% - International standard: phenyl-hexane - Detector: Detector differential refractive index - Columns: to the numbers of two, 60 cm from Polymer Labs., mixed gel 10 microns - Data exploitation: Calibration software from Polymer labs.

Samples (100 mg) are carefully weighed and dissolved in 40 ml of THF in 50 ml flasks. Then 50 microliters of label are added when the polymer is dissolved and the solutions are made up to the 50 ml mark. Finally, they are filtered through a 0.2 μΜ pressure filter and injected into the GPC. Four separate solutions of different mixtures of polystyrene standards are prepared in volumetric glass flasks and a known volume of label is added.

The marker is used to correct flow variations. The software creates a calibration curve from the standard mixtures using a third-order polynomial fit.

The values obtained for various elastomers that are suitable for carrying out the subject of the invention are listed in the following table:

It is important to note that other methods of measuring the molecular weight of these elastomers can induce a margin of error causing a more or less significant fluctuation in the result obtained.

According to a preferred embodiment of the present invention, the elastomeric matrix comprises a triblock type elastomer, as described above, having a molecular weight of between 200,000 and 29,000 Dalton, and preferably between 2,300,000 and 29,000 Dalton measured by permeation chromatography. of gel.

Advantageously, a hydrogenated elastomer of polystyrene-b-poly (ethylene-butylene) -b-polystyrene type (S-EB-S, for example Kraton G 1651 EU) is used.

Alternatively, a matrix comprising an elastomer of the Septon brand such as the Septon® 2005 elastomer or another elastomer of the Septon or Kraton® brand listed in the preceding table or else any elastomer having the molecular weight properties. mentioned above but being not listed in the previous table is contemplated by this embodiment.

According to an alternative embodiment of the present invention, the elastomeric matrix may comprise a diblock type elastomer having properties in terms of molecular weights similar to those of the elastomers described above.

According to a preferred embodiment of the invention, the elastomeric hydrophobic matrix comprises strictly less than 3.0% of elastomers relative to the total weight of the matrix, preferably between 1.5 and 2.6%, and so even more preferred 2.6%.

In addition to the elastomer, the hydrophobic elastomeric matrix also comprises at least one oily plasticizer, preferably constituting the majority by weight of the elastomeric hydrophobic matrix.

The oily plasticizer may in particular be constituted by a plasticizing oil and / or petroleum jelly. Due to the combination of a high proportion of oily plasticizer with a small proportion of triblock elastomer, the matrix has a very good compatibility with the tissues and very good properties of non-adhesion to the wound but also of protection and tolerance perilesional skin.

Among the oily plasticizers suitable for forming the hydrophobic matrix according to this embodiment, that is to say allowing the plasticization of the elastomer, there may be mentioned paraffin oils, medicinal white oils, mineral oils, petrolatum, paraffins of balm, silicone oils, vegetable oils, waxes or mixtures thereof.

Preferably, the plasticizer will consist of a liquid or liquid mixture compatible with the saturated polyolefin core sequence of the triblock elastomer used.

Among the plasticizer compounds that may be used for this purpose, mention may be made in particular of mineralizing plastic oils, whatever the nature of the central block. Mention may also be made of polybutenes, for example the products marketed by LIPO Chemicals under the name INDOPOL® or else phthalate derivatives such as dioctylphthalate or dioctyladipate, when the central block is unsaturated.

Alternatively, it is also possible to use synthetic products based on liquid mixtures of saturated hydrocarbons, for example the products sold by the company TOTAL under the name GEMSEAL and in particular the product d) GEMSEAL 60 which is an isoparaffinic mixture derived from a completely hydrogenated petroleum cut. These products will preferably be used with a triblock copolymer comprising a saturated central block.

In the context of the present invention, it is preferable to use plasticizing oils and in particular mineral oils formed of compounds of paraffinic, naphthenic nature or of their mixtures in variable proportions.

Among the plasticizing oils that are particularly suitable, mention may be made of the products marketed by SHELL under the names ONDINA® and RISELLA® which consist of mixtures based on naphthenic and paraffinic compounds. In a particularly preferred manner, use will be made of a mineral plasticizing oil chosen from the products sold under the names ONDINA®963, ONDINA®917 and ONDINA®919.

According to other alternatives, it is possible to use other plasticizing oils such as Pionier® 2076P or 2071 N oils marketed by Hansen & Rosenthal, Puretol® 9D oil marketed by Petro Canada, and Marcol 82 oil marketed by Exxon.

According to a preferred embodiment of the invention, the plasticizing oil is present at a level of from 20 to 85% by weight relative to the total weight of the elastomeric matrix, preferably from 50 to 80%, and even more preferably from 70 to 80%.

According to a particular embodiment, a quantity of oil chosen may be substituted in whole or in part by an equivalent amount of petrolatum, in particular of the Codex A® vaseline marketed by Aiglon®.

According to another particular embodiment, a quantity of petrolatum may simply be added to the quantity of oil chosen within the hydrophobic elastomeric matrix.

According to a preferred embodiment of the present invention, the petrolatum represents from 0 to 18% of the total weight of the elastomeric matrix.

The matrix may also contain antioxidants. Suitable antioxidants that may be mentioned include phenolic antioxidants, for example the products sold under the name IRGANOX® 1010, IRGANOX® 565 and IRGANOX® 1035 by the company BASF.

In the context of the present invention, the compound IRGANOX® 1010 is preferred.

According to a particular embodiment of the invention, the antioxidant is present in an amount of from 0.05 to 5%, preferably from 0.1 to 3% by weight relative to the total weight of the elastomeric matrix.

The hydrophobic elastomeric matrix according to a particular embodiment of the invention may further comprise an additive selected from the group consisting of stabilizing agents, extrusion aids, fillers, pigments, dyes, crosslinking agents. , anti-odorants, adhesion promoters, compatibilizers and combinations thereof.

In addition, said matrix may comprise at least one type of hydrophilic organic or inorganic water-binding particles such as hydrocolloids or superabsorbent polymers. Suitable hydrocolloids include, for example, pectin, alginates, natural vegetable gums such as, in particular, Karaya gum, cellulose derivatives such as carboxymethylcelluloses and their alkali metal salts, such as sodium or calcium salts. as well as synthetic polymers based on salts of acrylic acid, known under the name "superabsorbents", for example the products sold by BASF under the name LUQUASORB® 1003 or by BASF under the name SALCARE ® SC91 as well as mixtures of these compounds.

The hydrocolloids preferred in the context of the present invention are the alkali metal salts of carboxymethylcellulose, and in particular sodium carboxymethylcellulose (CMC) known under the reference Blanose® 7H4XF PH. The size of the hydrocolloid particles is for example between 50 and 100 microns, in particular of the order of 80 microns.

The amount of hydrocolloids incorporated in the elastomer composition will advantageously be of the order of 2 to 20% by weight, preferably 5 to 18% by weight, more preferably 8 to 18% by weight, based on the total weight of the composition. elastomeric composition.

An active agent can also be added within this matrix. This active agent may be a cicatrizing agent, an anti-viral agent, antifungal agent, an anti-pain agent, an anti-bacterial agent, an anti-inflammatory agent, a keratolytic agent, an immunomodulating agent, a chelating agent a modifying agent, an agent of the extracellular matrix.

For the purposes of the present invention, the term "healing promoting agent" is intended to mean any compound chosen from the non-limiting list consisting of retinol, vitamin A, vitamin E and its derivatives, N-acetylhydroxyproline, extracts of Centella Asiatica, Papain, Hyaluronic acid, synthetic polysulfated oligosaccharides having 1 to 4 units of osteos, their salts and complexes, such as, for example, the alkaline salts of sucrose octasulfate (among which are found inter alia sucrose octasulfate potassium salt or sucrose octasulfate sodium salt), sucralfate, sucrose octasulfate amino acid salts, or sucrose octasulfate silver salt, allantoin, and metformin.

For the purposes of the present invention, the term "anti-viral agent" is intended to mean any compound chosen from the nonlimiting list consisting of acyclovir, famciclovir and ritonavir.

For the purpose of the present invention, the term "antifungal agent" is intended to mean any compound chosen from the nonlimiting list consisting of nystatin, amphotericin B, natamycin, miconazole, ketoconazole, clotrimazole, econazole, bifonazole, butoconazole, fenticonazole, isoconazole, oxiconazole, sertaconazole, sulconazole, thiabendazole, tioconazole, fluconazole, itraconazole, ravuconazole, posaconazole, voriconazole, allylamine, terbinafine, amorolfine, naftifine, and butenafine.

For the purpose of the present invention, the term "pain-relieving agent" is intended to mean any compound chosen from the nonlimiting list consisting of paracetamol, codeine, dextropropoxyphene, tramadol, morphine and its derivatives and corticosteroids and its derivatives. derivatives.

For the purposes of the present invention, the term "anti-bacterial agent" is intended to mean any compound chosen from the non-limiting list consisting of salts or complexes of silver (such as silver sulphates, silver nitrates, sulphonamides of silver, silver sulfadiazine or silver-based zeolites), zinc or copper salts, metronidazole, neomycin, penicillins, clavulanic acid, tetracyclines, mynocycline, chlorotetracycline, aminoglycosides , amikacin, gentamicin, or probiotics.

For the purpose of the present invention, the term "anti-inflammatory agent" is intended to mean any compound chosen from the non-limiting list consisting of non-steroidal anti-inflammatory drugs (NSAIDs), aspirin or acetylsalicylic acid, ibuprofen, ketoprofen, flurbiprofen, diclofenac, aceclophenac, ketorolac, meloxicam, piroxicam, tenoxicam, naproxen, indomethacin, naproxcinod, nimesulid, celecoxib, etoricoxib, parecoxib, rofecoxib, valdecoxib, phenylbutazone, niflumic acid, and mefenamic acid.

For the purpose of the present invention, the term "keratolytic agent" is intended to mean any compound chosen from the non-limiting list consisting of salicylic acid, zinc salicylate, ascorbic acid and alpha-hydroxylated acids (such as glycolic acid, lactic acid, malic acid, citric acid, tartaric acid), extracts of Silver Maple, Griottier, or Tamarinier, urea, Keratinol (marketed by Sederma), and papain.

Finally, "immunomodulatory agent" is understood to mean beta-glucan, "chelating agent" means ethylene diamine tetraacetic acid (EDTA) and hydroxamic acids, "pH-modifying agent" means bicarbonate. sodium, and by "extracellular matrix agent" is meant glycosaminoglycans, hyaluronic acid, dermatan sulfate, heparan sulfate, elastins, and laminin.

Preferably, a biguanide, such as polyhexamethylene biguanide. (PHMB), or hydrophobic PHMB stearate is added to said matrix.

According to a particular embodiment of the invention, the active agent is present in an amount of 1 to 7.5%, preferably 5%, by weight relative to the total weight of the elastomeric matrix.

In addition, the elastomeric matrix may include, if necessary, a release agent such as the MONTANOX® 80 PHA PREMIUM surfactant which is a polysorbate 80 or the SEPINOV® EMT 10 polymer both marketed by SEPPIC to optimize the gelation rate. , the wettability or the release of assets possibly present in the composition.

According to a particular embodiment of the invention, the salting agent is present in an amount of 1 to 15% by weight relative to the total weight of the elastomeric matrix.

If it is desired that the elastomeric matrix is micro-adherent, the hydrophobic elastomeric matrix may contain a tackifier product. The tackifying products that may be used in the context of the present invention may be chosen from tackifying resins, polyisobutylenes of low molecular weight, or mixtures thereof.

By hydrophobic "microadherent" elastomeric matrix is meant any dressing matrix having an adhesive strength on a steel plate of between 0.5 and 100 cN / cm, preferably between 5 and 40 cN / cm. This adhesive power is measured according to the method EN 1939 in which a dressing sample of 20 mm wide and 150 mm long is placed on a steel plate and in which the adhesive power is measured after 10 minutes. a dynamometer at a pulling speed of 100 mm / min at an angle of 90 °.

Among the tackifying resins that may be used according to the invention, mention may be made of modified polyterpene or terpenes resins, rosin resins, hydrocarbon resins, mixtures of cyclic, aromatic and aliphatic resins, or mixtures of these resins.

Such products are marketed for example: by the company ARAKAWA Chemical Industries under the name ARKON® P which are hydrogenated polycyclopentadiene resins; by the company EXXON Chemical under the name ESCOREZ and in particular the series of resins 5000 which are hydrogenated. by CRAY VALLEY under the name WINGTACK®, and in particular WINGTACK® 86 which is a synthetic resin formed of C5 / C9 or WINGTACK® 10 copolymers which is a synthetic polyterpene-based resin; by the company Eastman under the name KRISTALEX® and in particular KRISTALEX® 3085 which is a resin based on alpha-methylstyrene; by Kolon Industries under the name Sukorez® grades: SU-90; SU-100; SU-100S.

In general, in order to avoid the problems of coloration and stability of the unsaturated resins, the use of hydrogenated resins will be preferred, in particular with saturated central block triblock copolymers because they are much more compatible with them than the resins. unsaturated WINGTACK® type which is used essentially with unsaturated central block triblock copolymers.

Among the latter, it is preferable to use ESCOREZ® resins of the 5000 series and most particularly the ESCOREZ® 5380 resin.

Tackifying resins may be used alone or in admixture with other tackifying agents, preferably in a proportion of 5 to 50% by weight, and more particularly from 15 to 40% by weight, relative to the total weight of the composition.

Among the low molecular weight polyisobutylenes which may be used as tackifying products, mention may be made of polyisobutylenes having a molecular weight of the order of 40,000 to 80,000 daltons, for example the products sold by BASF under the name OPPANOL. and in particular the products sold under the names OPPANOL®B12 and OPPANOL®B15 or by the company EXXON Chemical under the name Vistanex and in particular the LM-MH grade.

These polyisobutylenes can be used alone or in admixture with other tackifiers in combination with the unsaturated central block triblock copolymer. Their proportion may vary in this case between 5 to 30% by weight, and more particularly from 8 to 15% by weight, based on the total weight of the composition.

The matrix of the dressing according to the invention can be defined as being a nonabsorbent elastomeric hydrophobic matrix.

The term hydrophobic elastomeric matrix "non-absorbent" means any hydrophobic elastomeric matrix as described above and which absorbs less than 35% of a saline solution (0.8% NaCl solution) in 24 hours relative to the dry weight of the matrix.

Support

The support of the dressing according to the invention advantageously has through holes. In general, this support can be in the form of an open wide mesh fabric and can be obtained by weaving or knitting processes to form open meshes of regular size, rectangular, square or polygonal. In the case of weaving, the stitches can be fixed by means of turn threads in order to obtain a good dimensional stability. The mesh size is such that the unit area of the openings is of the order of 0.5 to 10 mm 2, preferably 0.5 to 3 mm 2, the rate of opening of the fabric (ratio of the open area to the total area ) being of the order of 50 to 90%. In general, the yarn used to make the fabric consists of continuous or non-continuous filaments, extensible or non-extensible and elastic or non-elastic. This yarn is preferably a continuous yarn with filaments, which is not very extensible and inelastic, the extensibility or elongation being less than 35%. By continuous filament yarn is meant a yarn formed of one or more long, stranded filaments; the choice of long filaments makes it possible to avoid short fibers which may become detached from the support and disperse near the contact surface with the wound.

For the same reason, the constituent material of the yarns is preferably of the hydrophobic type, of artificial or synthetic nature; these constituents, such as, for example, polyesters, polyamides, cellulose acetates make it possible to obtain long filaments and yarns with considerably fewer fibrils than the yarns obtained from short fibers, for example. The choice of certain synthetic materials such as polyesters also gives the possibility of heat setting the wide mesh structure of the support. The wide-meshed fabric is preferably made with yarns of the same kind, but it is also possible to use fabrics made for example with warp yarns and weft yarns which would be of a different nature. Finally, another advantage of very little extensible and non-elastic materials, such as polyesters, is an easier implementation during the method of covering the yarns of the fabric with the hydrophobic elastomeric matrix.

According to a preferred embodiment of the invention, the hydrophobic elastomeric mass is applied to the wide-meshed fabric so as to coat the yarns of the fabric leaving a majority of the stitches unobstructed.

As indicated previously, a woven or knitted support is used having rectangular, square or polygonal wide meshes whose opening corresponds substantially to 4 to 20 meshes per cm, the fabric having an open ratio (ratio of the open surfaces to the surface total) of 50 to 90%. The yarn used to obtain the support is preferably a continuous filament yarn, and in order to carry out the preferred examples of the invention, yarns made of artificial or synthetic material with a hydrophobic nature and an extensibility of less than 35% are chosen.

The nature of the yarn is, for example, a polyethylene terephthalate type polyester, a polyamide or a cellulose acetate; it is preferable to use a wide-knit, thermofixed fabric made of polyester (Tergal or polyethylene terephthalate) continuous yarns, for example fabrics marketed under the name of marquisette, which weights about 30 to 80 g / m 2. These fabrics which are practically non-extensible in the warp or weft directions have the advantage of being easier to work than elastic fabrics and a more even coating of the threads is obtained.

This type of support formed of a yarn fabric of flexible material and very little extensible and inelastic is described in particular in the patent application WO 00/16725.

Alternatively, the fabric constituting the support may be a thermofixed knit with screened yarns, said threads being non-elastic filament continuous yarns, which has in the transverse direction an extensibility measured according to standard NF EN 13726-4 between 0.01 and 0.5 N / cm, preferably between 0.05 to 0.3 N / cm, and more preferably between 0.08 to 0.15 N / cm.

According to a preferred version of the present invention, this knit will present in the longitudinal direction an extensibility measured according to the same standard of between 15 and 30 N / cm and preferably between 20 and 25 N / cm. Such extensibility in the longitudinal direction indeed allows an easier and more regular coating of the knitted fabric by the hydrophobic elastomeric matrix from the industrial point of view.

In general, this knit is made with screened yarns, and will be manufactured in particular according to the technology called "knit stitches".

In addition, this knit is heat-set. This thermofixation makes it possible to stabilize the structure of the knitted fabric after knitting by thermal effect. This thermofixation operation is commonly used by those skilled in the art during the manufacture of a knit which is wanted to freeze the three-dimensional structure. It can be implemented using different technologies either by passing the knit in a series of thermoregulated furnaces, or by passing the knit in an autoclave, or by passing the knit between one or more heated cylinders. In the context of the present invention, it will be preferred to carry out this heat-setting operation by passing the knit between two heated rolls.

According to the invention, this knit is made using continuous filaments with non-elastic filaments. By continuous filament yarn is meant a yarn formed of one or more long, stranded filaments.

This yarn will preferably be chosen from 33 to 115 dtex yarns comprising 12 to 36 filaments.

The constituent material of the yarns is preferably of a synthetic and hydrophobic nature. This material is advantageously chosen from polyesters and polyamides.

According to the preferred version of the invention, use will be made of a knit with heat-fixed screen yarns based on continuous yarns of 50 dtex polyester comprising 24 filaments.

This knit may have a grammage of between 20 to 40 g / m 2 and preferably between 24 to 32 g / m 2.

This knit may have rectangular, square or polygonal meshes.

These meshes will advantageously have openings whose unit area before coating is of the order of 0.5 to 3 mm 2 and preferably between 0.85 and 1.25 mm 2.

According to a preferred embodiment, use will be made of a knit that has trapezoidal meshes.

According to a preferred version of the present invention, use will be made of a knit that has trapezoidal meshes. A knit with such a mesh is schematically illustrated in FIG. 1. The angle a is defined as the average connection angle of the rows (1) and columns (2) of the knit.

According to the preferred version of the present invention, this knit has an average mesh surface of the order of 0.95 mm 2 and an angle a as described in FIG. 1 between 75 and 85 degrees. The coating of the hydrophobic elastomeric matrix in the molten state on the knit defined according to this first embodiment is carried out in such a way as to leave the stitches essentially unsealed, according to the techniques known to those skilled in the art and in such a manner as to to obtain a coating weight which varies from 100 to 160 g / m2 and preferably from 125 to 145 g / m2.

In the context of the present invention, to achieve this coating it will be preferred to implement the method described in patent application WO 00/16725.

Figure 1 attached schematically shows a mesh of the fabric of a dressing according to a preferred embodiment of the invention.

According to a second alternative embodiment, it is possible to use another type of support formed of an open-meshed fabric consisting of little extensible and not very elastic threads. These son are preferably polyester. They are woven multi-filament yarns with a diameter of between 10 and 20 μm and preferably around 16 μm. The mesh size is between 1 and 1.1 mm 2 and preferably about 1.05 mm 2. This support preferably comprises a number of 7 threads per cm taken in its longitudinal direction, and a number of 8 threads per cm taken in its transverse direction. The basis weight of this support is between 40 and 45 g / cm 2 and is preferably about 43 g / cm 2. Finally, its extensibility at 20% was measured according to standard NF EN 13726-4. The latter is between 20 and 30 N / cm in the longitudinal direction, and is preferably 24 N / cm. In the same way, this extensibility in the transverse direction is between 1 and 5 N / cm and is preferably 3 N / cm.

According to a third alternative embodiment, it is possible to use a woven or knitted support having rectangular, square or polygonal wide meshes whose opening corresponds substantially to 4 to 20 meshes per cm, the fabric having an open ratio (ratio of open surfaces on the total area) from 50 to 90%. The yarn used to obtain the support is preferably a continuous filament yarn, and yarns made of artificial or synthetic material with a hydrophobic nature and an extensibility of less than 35% are chosen. The nature of the yarn is, for example, a polyester of polyethyl terephthalate type, a polyamide or a cellulose acetate; it is preferable to use a wide-knit, thermofixed polyester continuous filament yarn (Tergal or polyethyl terephthalate), for example fabrics marketed under the name of marquisette, having a basis weight of between 30 and 80 g / m 2. These fabrics which are practically non-extensible in the warp or weft directions have the advantage of being easier to work than elastic fabrics and a more even coating of the threads is obtained.

Pad

According to a preferred embodiment of the present invention, the textile support is coated with the hydrophobic elastomeric matrix.

This coating is carried out by passing through an elastomeric matrix bath which is in the molten state at 110-145 ° C., then the excess is removed by passing between two fixed rolls, the difference of which is predetermined according to the basis weight. desired coating. The support is then cooled by an upward cold air flow. The amount of elastomeric matrix in the molten state deposited on the yarns of the fabric is between 50 and 300 g / m 2, preferably between 100 and 150 g / m 2. The basis weight of the overall dressing (support and elastomeric matrix) is between 80 and 380 g / m 2, and preferably between 100 and 300 g / m 2.

According to a very particular embodiment of the present invention, this dressing or this elastomeric matrix can serve as an envelope for a cavitary wound filling material in negative pressure therapy as described in patent applications WO2009 / 071928 and US Pat. W02009 / 071938 of Smith and Nephew or in the Urgo Laboratories application filed under number FR 13 63162.

Examples

The present invention is further illustrated in the following non-limiting examples.

Example 1: Realization of a dressing according to the subject of the invention

The elastomeric matrix is prepared using a vertical mixer at approximately 140 ° C. by mixing 15.2 kg of paraffin oil (ONDINA 919 marketed by SHELL), ie a total of approximately 75% of the mass of the matrix. and 3.04 kg (about 15% of the total weight of the final elastomeric matrix) of sodium carboxymethylcellulose (Blanose ref.7H4XF PH sold by Ashland). When sodium carboxymethylcellulose is dispersed in the oil, 1.2 kg (ie approximately 5% of the mass of the matrix) of petrolatum (quality in accordance with the French Pharmacopoeia or Codex) is added. After melting of the petrolatum, 0.535 kg (ie approximately 2.6% relative to the weight of the final elastomeric matrix) of a Kraton G 1651 EU type elastomer and 25 g of antioxidant (IRGANOX 1010) are added. After 45 to 60 minutes of mixing, the elastomeric matrix which is in the molten state can be used to coat the yarns of the fabric. The fabric used is a marquisette heat-fixed polyester yarn (polyethyl terephthalate), 33 decitex warp and weft, having square mesh whose opening is about 0.8 to 1 mm 2; the basis weight of the fabric is approximately 45 g / m2 (this fabric is manufactured by TEXINOV). The fabric is coated with an elastomeric matrix layer by passing through an elastomeric matrix bath in the molten state at 110-145 ° C., then the excess is removed by passing between two fixed rolls whose difference is predetermined in depending on the desired coating weight. The coated textile support is then cooled by a rising cold air stream. The amount of elastomeric matrix deposited on the yarns of the fabric is about 130 g / m 2. The coated textile support is complexed with a protective film of polyester thickness 23 μπι on each of its faces, then cut into sheets to form compresses, each packaged in a sealed pouch and sterilized under β radiation.

EXAMPLE 2 Comparative Oil Release Measurements of Different Elastomeric Matrixes for Dressings

The measurement method consists of several steps, namely:

The production of a 4 mm thick mass plate using a heating press at 100 ° C.

The cutting of a mass sample of 4x4 cm in the plate using a punch The placement of said sample obtained in the previous step between two paper towels for a few seconds The weighing of said sample

Placing said sample on a 500 μm sieve

The repetition of each of the preceding steps for the other mass samples to be tested The placement of a silicone polyester film on the various samples tested

The placement of a rigid plate on the silicone polyester film covering the tested samples on which is placed a weight of 750 g, for the purpose of distributing the best weight over the entire test device The oven setting of the set at 37 ° C The output of each sample tested at different predefined times, the placement of each test sample taken out of the oven between two paper towels for a few seconds and the weighing of each sample.

The tested samples are:

The elastomeric dressing matrix as described in Example 1 of Patent EP 2,524,706. This example discloses an elastomeric dressing matrix comprising a Septon 4055 type elastomer, the elastomer portion being 2.6% by weight. total of the matrix.

The elastomeric matrix for dressing as described in patent EP 1 272 229. The elastomeric matrix described may comprise 3% by weight of a Kraton G 1651 type elastomer, relative to the total weight of the matrix.

The elastomeric matrix according to Example 1 of the present invention.

The results of the oil loss measurements of the various samples tested are given in the following table:

Matrix time Matrix Matrix elastomeric elastomeric elastomer produced product of the product of the product tested on according to the according to the paper example 1 description example EP absorbent EP 1 of patent 2,524,706 1,272,229 discloses 0 minute 000 199 0.80 0.80 0.80 minutes 1385 2.4 1.8 2.8 minutes 2832 4.1 3.4 4.6 minutes

The values given are expressed in% of quantity of oil released from the mass

It is found that the matrix used in the composition of the product according to Example 1 of the present invention has oil loss levels substantially higher than those used in the composition of the comparative products concerned. This seems to be due to a surprising and synergistic effect of the percentage of the elastomer introduced into the elastomeric matrix and to the choice of said elastomer having certain properties of desired molecular weight.

The exhaustive trends in the results presented in this table are confirmed by tests carried out over longer periods, the differences in% of the amount of oil released being significantly more important.

Example 3 Comparative Integrity Measurements of Different Elastomer Matrixes for Dressings

The method of measuring integrity values of a mass comprises several steps, namely:

The initial weighing of any of the samples of Example 2 after the oil release measurement performed in said previous example and after placing said sample between two absorbent papers for a few seconds - Placing the sample in a jar - The addition of 50 mL of physiological saline solution (NaCl solution at a concentration of 9.0 g / 1) - The setting of the whole stirring tangential for 18 hours at 100 shakes per minute - Cutting a piece 6x6 cm aluminum foil and its weighing - The withdrawal of the test sample after 18 hours of agitation - The placement of the sample obtained in the previous step between two paper towels for a few seconds - The installation of the sample on said piece of aluminum - The placement of the previously described assembly in an oven at 70 ° C for 24 hours - The removal of the entire oven and the conditioning of said sample during 1 hour, at a temperature of 21 ° C and at a moisture level of 60% - The placement of said sample obtained in the previous step between two absorbent papers for a few seconds - The final weighing of the tested sample placed on paper aluminum

The samples tested in this example are the same as those tested previously, namely:

The elastomeric dressing matrix as described in Example 1 of Patent EP 2,524,706. This example discloses an elastomeric dressing matrix comprising a Septon 4055 type elastomer, the elastomer portion being 2.6% by weight. total of the matrix.

The elastomeric matrix for dressing as described in patent EP 1 272 229. The elastomeric matrix described may comprise 3% by weight of a Kraton G 1651 type elastomer, relative to the total weight of the matrix.

The elastomeric matrix according to Example 1 of the present invention.

The results of the integrity measurements of the different samples tested are given in the following table:

The calculation of the integrity values is done according to the following mathematical formula:

Integrity = 100 x (mass of the sample obtained during the final weighing - mass of the piece of alumininum paper of size 6x6 cm) / (mass of the sample obtained during the initial weighing)

The value of each of the integrity measurements is obtained as a percentage of the weight of the starting sample.

Thus values greater than 99.5% demonstrate perfect cohesion of the elastomeric matrix subjected to said integrity test.

The elastomeric matrices obtained according to Example 1 of the present invention demonstrate as strong cohesion as the comparative matrices tested.

Claims (11)

A dressing comprising a support and a hydrophobic elastomeric matrix coating said support, said matrix comprising an elastomer of SEPS, SEBS or SEEPS type, consisting of a combination of polystyrene blocks and polyolefin blocks, said elastomer having a molecular weight of less than or equal to at 290000 Dalton measured by gel permeation chromatography, the total elastomer fraction being strictly less than 3.0% of the total weight of said elastomeric matrix. 2. Dressing according to claim 1, characterized in that the elastomer has a molecular weight between 200000 and 290000 Dalton measured by gel permeation chromatography. 3. Dressing according to claim 1 or 2, characterized in that the total elastomer share is between 1.5 and 2.6% of the total weight of the elastomeric matrix. 4. Dressing according to any one of the preceding claims, characterized in that the elastomeric matrix comprises at least one plasticizing oil, preferably of naphthenic and / or paraffinic nature. 5. Dressing according to the preceding claim characterized in that the plasticizing oil represents from 20 to 85%, preferably from 50 to 80%, and more preferably from 70 to 80%, of the total weight of said elastomeric matrix. 6. Dressing according to any one of the preceding claims, characterized in that the elastomeric matrix comprises petroleum jelly. 7. Dressing according to the preceding claim characterized in that the petrolatum represents from 0 to 18% of the total weight of the elastomeric matrix. 8. Dressing according to any one of the preceding claims, characterized in that the elastomeric matrix comprises at least one hydrocolloid representing 2 to 20% of the total weight of the elastomeric matrix. 9. Dressing according to any one of the preceding claims, characterized in that the elastomeric matrix further comprises an active agent. 10. Dressing according to the preceding claim, characterized in that the active agent is hydrophobic polyhexamethylene biguanide stearate, said agent representing from 1 to 7.5% of the total weight of the elastomeric matrix. 11. Dressing according to any one of the preceding claims, characterized in that the support is a textile formed by a son assembly consisting of continuous or non-continuous filaments, said filaments being extensible or non-extensible and elastic or non-elastic.