EP1950765A1 - Multi-layer elastomer material charged with radiation attenuator compounds, preparation method and uses of same - Google Patents

Abstract

The material has two outer layers (L1, L3) imprisoning an intermediate layer (L2) which is constituted by an elastomer matrix. The matrix has a dispersion of droplets of liquid or gelled compositions enclosing a radio-opaque substance that is in a form of solid particles. A voluminous fraction of the radio-opaque substance within the intermediate layer is higher or equal to 20 percent. The composition in the form of the droplets encloses diluents which are chosen from glycerine, ethylene glycol, polyethylene glycol liquides.

Description

The present invention relates to a multilayer elastomer material having the property of attenuating radiation such as, for example, X and gamma radiation, to its preparation process, as well as to its use for the manufacture of protective articles against radiation, in particular X and / or gamma radiation.

In the space of a century, diagnostic radiology, nuclear medicine and radiotherapy have developed considerably to the point of becoming essential and essential tools in all medical specialties. Although the properties inherent in ionizing radiation, especially X and gamma (y), have many advantages, the increasing use of such techniques exposes the general population to increasing doses. This exposure particularly affects medical personnel whose almost daily exposure to radiation leads to cumulative doses that are not without danger to their health. This is particularly the case in interventional surgery where medical personnel are brought to work in the X-ray field. Repeated exposure to these radiations, even at low doses, leads to long-term detrimental effects such as dermatitis, or even in some cases, cancers. Medical personnel operating directly in the X-ray field, or using equipment generating X-rays, therefore require special protection against these radiations in order to limit or attenuate the doses received.

Devices for protecting sensitive areas of the body or areas highly exposed to such radiation are well known. They include aprons, gloves, thyroid protectors and gonad shields, comprising a polymer matrix in which have been incorporated radio-opaque substances to mitigate radiation.

The radio-opaque substances used in the prior art are mainly based on lead in metallic form, oxides (PbO ₂ ) or salts. For example, such substances have been described in the patents US 3,185,751 and US 3,883,749 for the production, by dipping process, of surgical gloves made of natural latex and polyurethane respectively. The use of a mixture of lead and mercury has also been described, in particular in the patent GB 954 593 for the production of multilayer protection materials against ionizing radiation. According to this patent GB 954 593 , the materials including in particular a continuous layer consisting of an intimate mixture of a lead / mercury amalgam and neoprene said layer further comprising a dispersion of mercury droplets. But the use of lead-based particles is known to accelerate the vulcanization phenomena in mixtures formulated natural latex and thus significantly reduces the duration of use of these mixtures. Thus, at a relatively high content of lead, a mixture of natural latex deteriorates too rapidly and becomes unusable for the manufacture of radiation-attenuator gloves in a quenching process. In addition, the use of lead more generally poses an environmental problem requiring specific sectors of waste disposal from the manufacturing process but also for finished products.

More recently, lead has been replaced in favor of elements with comparable X-ray attenuation efficiencies in the energy domains generally considered in interventional surgery (between 60 and 120 kV), such as bismuth and tungsten. For example, in the patent application US 2004/0262546 the bismuth element is used in the form of oxide dispersed in a natural rubber matrix for producing surgical gloves. Similarly, the use of the tungsten element is described in the patents US5,215,701 and US5,548.125 for making surgical or medical gloves made of natural rubber or based on ethylene propylene diene monomer (EPDM).

The substitution of lead by bismuth or tungsten provides undeniable advantages in terms of the stability of the mixtures involved in the glove manufacturing processes, but especially in terms of the lack of toxic effect recognized for the health of people and for the environment.

The effectiveness of these X-ray attenuators depends directly on the amount incorporated in the polymer matrix, or more exactly, the volume fraction of charge in the matrix and the thickness of that matrix. Thus, the surgical gloves based on bismuth and tungsten oxide described in the patent application US 2004/0262546 have relatively low X-ray attenuation rates, ranging from 23% at 100 kV to 58% at 60 kV, ie these levels are at most equivalent to a lead thickness of 0 02 mm. This low efficiency is explained by a relatively small volume fraction (s) radio-attenuator (s) in the polymer matrix and a reduced thickness of the gloves of the order of 0.3 mm so as not to penalize too much the flexibility and comfort of the glove. Indeed, it is well known that the incorporation of solid particles in the form of charges in a polymer matrix causes a significant increase in its low-elongation modules, and consequently leads to a significant loss in terms of flexibility and comfort gloves. This is particularly the case of the gloves described in the patent US5,548.125 which are heavily loaded with tungsten particles (40% by volume) whose efficiency is certainly better, greater than 0.1 mm in lead equivalent, but whose stiffness and the resulting discomfort make them unusable for the exercise of surgery.

It emerges from these few examples that, a priori, the efficiency to attenuate X-rays is incompatible with the criteria of comfort and flexibility; a soft and comfortable glove will be ineffective because it is not loaded with radio attenuator element (s), conversely, an effective glove (≥ 0.1 mm in lead equivalent) will be unusable in interventional surgery because of its stiffness because too much charge.

For these reasons, because they are too inefficient in terms of their cost and / or too uncomfortable to wear, the protective devices currently on the market, and first and foremost the radioprotective surgical gloves, are used very little. , exposing personnel working directly in the field or exposed to the X-ray secondary beam to the risk of serious trauma. Faced with the increasing use of these medical and surgical techniques using X-rays, it seems necessary to provide an uncompromising response to the criteria of effectiveness of attenuation and comfort, the only guarantee of a good end use products, and therefore the protection of the staff concerned.

The inventors have therefore set themselves the goal of providing a multilayer elastomeric material containing at least one radio-opaque substance, particularly suitable for use in the medical or paramedical field for the manufacture of protective devices having improved performance with respect to the attenuation of X-rays and the flexibility and comfort of said device compared with similar materials of the prior art.

On this occasion, the Applicant has discovered that, so surprisingly, it was possible to incorporate a large amount of radio-attenuator element (s) in an elastomer film that provides high X-ray attenuation, which can be greater than or equal to 0.1 mm in lead equivalent, while retaining the initial flexibility of said film when said substance is present in a dispersed phase in the form of liquid droplets within an elastomeric layer. Indeed, according to the invention, to avoid the phenomenon of stiffening inherent in the incorporation of fillers in an elastomeric material, the radio-opaque substance or substances are incorporated into liquid droplets themselves evenly dispersed in an elastomer film . The disappearance of the interface between the said charges and the matrix, as well as the mobile nature of the liquid dispersed phase largely eliminates the stiffening effect of the charges that cause poor performance in terms of product flexibility and comfort. existing.

The present invention therefore has for its first object a multilayer elastomer material comprising at least two external layers L1 and L3 trapping at least one intermediate layer L2, said intermediate layer being constituted by an elastomeric matrix comprising at least one dispersion of droplets of at least one composition containing at least one radio-opaque substance, said material being characterized in that the volume fraction φv of the radio-opaque substance (s) within layer L2 is greater than or equal to 20% and in that said composition is liquid or gelled and that said radio-opaque substance is in the form of solid particles.

In the material according to the present invention, the disappearance of the interface between said charges and the matrix, as well as the mobile nature of the liquid dispersed phase, largely eliminates the stiffening effect of the charges which cause the poor performances. in terms of flexibility and comfort of existing products. Thus, thanks to its particular constitution, said material has a modulus of elasticity at 100% elongation (M100) of between 0.2 and 1 MPa. According to a preferred embodiment of the invention, this module is between 0.2 and 0.7 MPa.

According to the invention, the term "radiopaque" substance is understood to mean any substance having a protective effect with respect in particular to exposure to X-rays, to ionizing radiation such as gamma and beta rays or to radiation used in radiotherapy, in particular for the treatment of cancers and any other radiation that has an adverse effect on the health of an organism that is exposed to it (radiation caused by the use of nuclear weapons, for example). Also within the meaning of the present invention, or by "protective effect" any reduction or suppression of the harmful effects caused by said radiation by reducing the amount of radiation transmitted in the energy field considered.

The material according to the present invention can be represented according to the scheme of the Figure 1A appended on which the layers L1 and L3 are the outer layers and L2 represents the intermediate layer containing the radio-opaque substance or substances dispersed in the form of droplets of a liquid composition.

In the material according to the present invention, the liquid containing the radio-opaque substance (s) is dispersed in a uniform and stable manner in the form of a droplet and thus makes it possible to offer a uniform attenuation of the radiation over the entire surface of the film.

According to this invention, the effectiveness of the multilayer material in attenuating radiation depends essentially on the characteristics of the layer L2, namely the droplet filling ratio, the droplet fraction brought back to the matrix of the L2 layer and the thickness of the L2 layer. The mechanical properties (tensile strength, elastic constant) of the material taken as a whole depend essentially on the intrinsic characteristics of the L1 and L3 layers, namely their mechanical characteristics (tensile stress and elastic constant) and dimensional characteristics (thickness).

The material according to the invention preferably has a radiation attenuation capacity, expressed in lead equivalent, greater than 0.02 mm.

According to the invention, the elastomeric material preferably has a total thickness of between 300 μm and 3000 μm inclusive.

The thickness of each of the layers L1, L2 and L3 of said material, which are identical or different, preferably varies between 50 and 2500 μm.

According to a preferred embodiment of the invention, the average diameter of the composition droplets containing the radio-opaque substance (s). is between 1 and 100 microns inclusive, and even more preferably between 1 and 10 microns inclusive.

According to the invention, the elastomer (s) constituting the outer layers L1 and L3 as well as the intermediate layer L2, are preferably chosen from natural rubber, polybutadiene, polyisoprene, polychloroprene, polyurethane, acrylic polymers or copolymers, silicone elastomers, copolymers SBR (Styrene Butadiene Rubber), SBS (Styrene Butadiene Styrene), isobutene-isoprene such as butyl rubber, NBR ( Nitrile Butadiene Rubber ), x-NBR ( Carboxylated Nitrile Butadiene Rubber ), SIS ( Styrene Isoprene) Styrene ), SEBS ( Styrene Ethylene Butylene Styrene ) and mixtures thereof; it being understood that the nature of the elastomer (s) constituting each of said layers may be identical or different from one layer to another.

The characteristics of the elastomers (molecular weight, crosslinking density (chemical and / or physical)) are of course selected according to the final characteristics desired for the material taken as a whole which must meet the constraints mentioned above. Thus, according to a preferred embodiment of the invention, the elastomer or elastomers are selected from SIS and SEBS.

In addition to the elastomers defined above, at least one of the layers L1 and L3, and / or the intermediate layer L2, may further contain one or more plasticizing agent (s) or flexibilizer (s) whose Chemical nature and content are compatible with the material characteristics defined previously.

When used, these plasticizers are preferably selected from mineral oils including paraffinic oils, naphthenic or aromatic oils and mixtures of these products.

When used, the plasticizer (s) preferably represent from 5 to 500 parts per 100 parts of elastomer constituting the layer in which they are present.

It should be noted that the chemical nature, the composition or the thickness of the L1 layer is not necessarily equivalent to that of the L3 layer.

Finally, each layer L1 or L3 may alternatively result from the superposition of two or more layers of chemical natures equivalent or not. In this case, the intrinsic characteristics of each of the L1 and L3 layers will be then those measured on each complete layer.

The intermediate layer L2 serves as a matrix for the droplets of composition containing the radio-opaque substance (s) used.

According to the invention, the nature of this radio-opaque substance may be chosen according to the characteristics of the radiation (X, gamma, beta, energy) that it is desired to attenuate. These substances will preferably be chosen from high atomic number chemical elements, more particularly from elements having an atomic number greater than or equal to 40, while avoiding toxic elements such as lead or mercury. Thus, according to a preferred embodiment of the invention, said material is free of lead and mercury. These elements include bismuth, tungsten, barium, iodine, tin and mixtures thereof, said elements being in the form of metal particles, oxide or salts. The particle size of the radio-opaque substance is preferably between 0.5 and 50 μm inclusive, and even more preferably between 0.5 and 5 μm inclusive.

In addition to the radiopaque substance (s), the droplet composition further contains one or more diluents. These diluents make it possible to improve the dispersion of said radio-opaque substance or substances.

This diluent may be chosen from polyols and preferably from glycerin, ethylene glycol, polyethylene glycols which are liquid at room temperature or at a temperature in the region of room temperature (between approximately 20 and 30 ° C.) and with a molar mass of between 62 (ethylene glycol) and 750 Daltons inclusive (polyethylene glycol: PEG 750) and mixtures thereof, as well as any other compound compatible with the radio-opaque substance (s) used.

In addition, the composition in the form of droplets containing the radio-opaque substance or substances may also contain one or more additives for adjusting the final characteristics of the mixture such as surfactants, dispersing agents or thickening agents.

The composition in the form of droplets containing the radio-opaque substance (s) may be in liquid (in the form of an emulsion) or gelled form. When it is in gelled form, said composition then contains at least one gelling agent preferably selected from gelatin and semi-crystalline poly (ethylene oxide). The gelation of this composition makes it possible to freeze the particles of the radio-opaque substance (s) inside the droplets and to prevent them from coming out of the droplets because of their very high relative density.

According to a particular embodiment of the invention, the intermediate layer L2 may be formed of a superposition of two or more intermediate sublayers each comprising a dispersion of droplets, the nature of the radio-opaque substances contained in each of said sub-layers. layers being the same or different from one underlayer to another. In this case, the intrinsic characteristics of the layer L2 will then be those measured on the complete layer.

According to another particular embodiment of the invention, the intermediate layer L2 is formed by a single layer containing a dispersion of droplets containing radio-opaque substances different from one droplet to another.

According to another particular embodiment of the invention, and in order to improve the performance of the material with respect to the attenuation of radiation, the radio-opaque substance or substances may be dispersed, in addition to the droplets, directly in the matrix of the L2 layer, for little, of course, that the characteristics of the material taken as a whole remain in accordance with the invention.

Each of the layers constituting the multilayer elastomeric material according to the invention may contain, in addition, other adjuvants conventionally employed in the polymer industry, such as, for example, antistats, lubricants, antioxidants, dyes, setting agents and the like. implement or adhesion promoters according to the particular properties that it is desired to provide so far, of course, that its adjuvants are compatible with each other and with the intrinsic characteristics of said material as defined above.

According to a variant of the invention, the multilayer elastomeric material may be reinforced by an elastic textile web of natural or synthetic organic fibers then serving as a support for one of the two or two L1 and L3 layers. When the textile weft is adjacent only to the L1 layer, this type of multilayer material can be represented by the diagram of the Figure 1B appended on which the layers L1 and L3 are the outer layers and L2 represents the intermediate layer containing the radio-opaque substance or substances dispersed in the form of droplets of a liquid composition, said layer L1 being surmounted by a textile frame.

The link between the various constituent layers of the material according to the invention may, optionally, be provided by a bonding agent or by a chemical or physico-chemical modification of any one of the layers. Such treatment, however, has no influence on the final characteristics of the material.

According to the invention, the term chemical modification means either a grafting or a chemical attack, and by physico-chemical modification a bombardment of the surface of the film with ions, electrons or photons.

Due to the presence of the radio-opaque substance (s), the multilayer elastomeric material according to the invention can be used for the manufacture of elastomeric articles for protection against radiation, in particular against X-rays, ionizing rays such as gamma and beta rays, as well as against radiation used in radiotherapy, especially cancer radiotherapy. According to a preferred embodiment of the invention, said material is used for the manufacture of elastomeric articles protecting against X-rays and / or gamma.

Although any form of presentation may be considered, these items are generally in the form of aprons, gloves, finger cots, thyroid protectors or even gonad guards.

• soit à préparer une émulsion stable formée par les gouttelettes d'une composition liquide renfermant la ou les substances radio-opaques dans une dissolution d'élastomère dans un solvant volatile par analogie à ce qui est décrit notamment dans le brevet EP 0 981 573 B1 ;
• soit à préparer une dispersion desdites gouttelettes sous forme gélifiées, ou cristallisées (microsphères) dans une dissolution de l'élastomère dans un solvant volatile par analogie à ce qui est décrit dans le brevet EP 0 771 837 B1 ;
• soit à déposer les gouttelettes, par exemple sous forme de microsphères ou de microcapsules sur la couche L1 et/ou L3, puis à recouvrir lesdites gouttelettes par un élastomère, soit sous forme d'une solution de celui-ci dans un solvant organique, soit sous forme d'une dispersion aqueuse (latex), soit sous forme solide.

The manufacture of the multilayer material as defined above can be carried out according to a coating process on a textile support for example, or alternatively by a process of successive quenching and evaporation of a shape corresponding to the intended use. in organic solutions or aqueous dispersions (latex) of the elastomer or elastomers chosen so as to successively form the layers L1, L2 and L3, the formation of the layer L2 being for example carried out according to one of the following methods:

• to prepare a stable emulsion formed by the droplets of a liquid composition containing the radio-opaque substance (s) in an elastomer solution in a volatile solvent by analogy to that described in particular in the patent EP 0 981 573 B1 ;
• either to prepare a dispersion of said droplets in gelled or crystallized form (microspheres) in a dissolution of the elastomer in a volatile solvent by analogy with that described in the patent EP 0 771 837 B1 ;
• either to deposit the droplets, for example in the form of microspheres or microcapsules on the layer L1 and / or L3, then to cover said droplets with an elastomer, either in the form of a solution thereof in an organic solvent, or in the form of an aqueous dispersion (latex), either in solid form.

During this process, each quench is followed by an evaporation period, usually in a thermostatically controlled oven, during which the solvent or water is removed.

• la figure 1A représente un matériau conforme à l'invention constitué de deux couches externes L1 et L3 et d'une couche intermédiaire L2 contenant la ou les substances radio-opaques dispersées sous la forme de gouttelettes d'une composition liquide ;
• la figure 1B représente un matériau conforme à l'invention et tel que représenté sur la figure 1A, mais dans lequel la couche L1 est en plus surmontée d'une trame textile.

In addition to the foregoing, the invention also comprises other arrangements which will emerge from the description which follows, which refers to examples of preparation of the radiopaque intermediate layer L2 and to an example of preparation of multilayer elastomeric materials. according to the invention can be in the form of protective gloves against X-rays as well as figure 1 annexed to which:

• the Figure 1A represents a material according to the invention consisting of two outer layers L1 and L3 and an intermediate layer L2 containing the radio-opaque substance or substances dispersed in the form of droplets of a liquid composition;
• the Figure 1B represents a material according to the invention and as represented on the Figure 1A but in which the layer L1 is additionally surmounted by a textile frame.

EXAMPLE 1 PREPARATION OF AN ELASTOMER BATH FOR THE PRODUCTION OF A RADIO OPAQUE INTERMEDIATE L2.

• Copolymère SEBS vendu sous la dénomination commerciale
  Kraton ® G1652 par la société Kraton Polymers 41,0 g
• Huile minérale blanche vendue sous la dénomination commerciale
  Primol ® 352 par la société Esso (agent plastifiant) 29,0 g
• Cyclohexane (Total) 200,0 g
• Substance radio-opaque : trioxyde de bismuth (Bi₂O₃) 318,0 g
• Diluant de la phase dispersée de l'émulsion : polyéthylèneglycol
  (PEG 200) 79,0 g

An elastomer bath B1 was prepared which can be used for producing a radiopaque intermediate layer L2, said bath having the following composition:

• SEBS copolymer sold under the trade name
  Kraton ® G1652 by Kraton Polymers 41.0 g
• White mineral oil sold under the trade name
  Primol ® 352 by Esso (plasticizer) 29.0 g
• Cyclohexane (Total) 200.0 g
• Radio-opaque substance: bismuth trioxide (Bi ₂ O ₃ ) 318.0 g
• Diluent of the disperse phase of the emulsion: polyethylene glycol
  (PEG 200) 79.0 g

The continuous phase of the emulsion consisted of about 13% by weight of a mixture of Kraton® G 1652 copolymer and Primol® 352 mineral oil used as a plasticizer. Within this mixture, the elastomer / plasticizer mass proportions were 100/70. The plasticized elastomer was left in contact with the solvent (cyclohexane) for 1 hour and 30 minutes in order to allow the dissolution of the copolymer / agent mixture. plasticizer.

This continuous phase contained a dispersed phase of radiopaque substance droplets formed of Bi ₂ O ₃ and PEG 200 in 80: 20 mass proportions. The dispersed phase was homogenized with the deflocculator for 10 minutes at 2500 rpm.

The dispersion of the radiopaque phase in the continuous phase was made using an Ultra-Turrax homogenizer disperser for 10 minutes at 15000 rpm or deflocculating for 20 minutes at 2500 rpm.

EXAMPLE 2 PREPARATION OF AN ELASTOMER BATH FOR REALIZING A RADIO OPAQUE INTERLAYER L2.

• Kraton ® G1652 28,0 g
• Primol ® 352 29,0 g
• Cyclohexane 224,0 g
• O-xylène 28,0 g
• Bi₂O₃ 256,0 g
• Diluant de la phase dispersée de l'émulsion : gélatine / eau / PEG 200 64,0 g

An elastomer bath B2 was prepared which can be used for producing a radiopaque intermediate layer L2, said bath having the following composition:

• Kraton ® G1652 28.0 g
• Primol ® 352 29.0 g
• Cyclohexane 224.0 g
• O-xylene 28.0 g
• Bi ₂ O ₃ 256.0 g
• Diluent of the disperse phase of the emulsion: gelatin / water / PEG 200 64.0 g

The continuous phase of the emulsion consisted of about 10% weight of a mixture of Kraton ® G1652 copolymer and Primol ® 352 mineral oil used as a plasticizer. Within this mixture, the elastomer / plasticizer mass proportions were 100 / 100. The plasticized elastomer was left in contact with the solvent for 1 hour and 30 minutes in order to allow the dissolution of the copolymer / plasticizer mixture. The solvent consisted of a mixture of cyclohexane (Total company) and ortho-xylene (Total company) in mass proportions 88:12.

This continuous phase contained a dispersed phase of radio-opaque substance droplets formed of Bi ₂ O ₃ dissolved in a mixture of gelatin, water and PEG 200, in 80: 20 mass proportions. This is homogenized with the deflocculator for 10 minutes at 2500 rpm.

The gelatin / water / PEG 200 mixture was prepared beforehand by dissolving the constituents for 2 hours in an oven at 60 ° C., in the respective proportions by mass 4: 86: 10.

The dispersion of the radiopaque phase in the continuous phase was made using an Ultra-Turrax homogenizer disperser for 10 minutes at 15000 rpm or deflocculating for 20 minutes at 2500 rpm.

EXAMPLE 3 PREPARATION OF AN ELASTOMERIC BATH FOR THE PRODUCTION OF A RADIOOPAQUE INTERMEDIATE LAYER CONTAINING BISMUTH TRIOXIDE IN THE TWO PHASES OF THE EMULSION.

• Kraton ® G1652 40,0 g
• Primol ® 352 28,0 g
• Cyclohexane 210,0 g
• Bi₂O₃ 724,0 g
• Diluant de la phase dispersée de l'émulsion : PEG 200 72,0 g

A bath of B3 elastomer used for the production of a radiopaque intermediate layer L 2 was prepared, said bath having the following composition:

• Kraton ® G1652 40.0 g
• Primol ® 352 28.0 g
• Cyclohexane 210.0 g
• Bi ₂ O ₃ 724.0 g
• Diluent of the disperse phase of the emulsion: PEG 200 72.0 g

The continuous phase of the emulsion consisted of a mixture (approximately 8% by weight relative to the solids) of Kraton® G 1652 copolymer and of the mineral oil Primol ® 352 used as a plasticizer. Within this mixture, the elastomer / plasticizer mass proportions were 100/70. The plasticized elastomer was left in contact with the solvent for 1 hour and 30 minutes to allow dissolution of the copolymer / plasticizer mixture. The solvent used was cyclohexane (Total company). About 450 g (45% by weight relative to the dry extract) of Bi ₂ O ₃ were added to the continuous phase of the emulsion. This was homogenized using an Ultra-Turrax homogenizer disperser for 5 minutes at a speed of 15,000 rpm.

This continuous phase contained a dispersed phase of radiopaque substance droplets consisting of Bi ₂ O ₃ dissolved in PEG 200 and in proportions by weight 80:20. This was homogenized with the deflocculator for 10 minutes at 2500 rpm.

The dispersion of the radiopaque phase in the continuous phase was made using an Ultra-Turrax homogenizer disperser for 10 minutes at 15000 rpm or deflocculating for 20 minutes at 2500 rpm.

EXAMPLE 4 PREPARATION OF MULTILAYER MATERIALS INTEGRATING AN INTERMEDIATE LAYER L2 RADIO-OPAQUES.

This example describes the preparation of a multilayer elastomer material in the form of a glove, said material being made from synthetic elastomer in a solvent medium.

A first elastomer bath was prepared in a solvent (cyclohexane) consisting of 20% by weight (relative to the solids content) of a mixture of SEBS copolymer sold under the trade name Kraton® G1652, by Kraton Polymers and a mineral oil (Primol® 352, Esso company) used as a plasticizer. Within this mixture, the elastomer / plasticizer mass proportions were 100: 30. This bath was used to make the barrier layers L1 and L3.

Furthermore, and according to each of the processes described in Examples 1 to 3, the three elastomer baths containing a dispersion of radiopaque substance droplets (baths B1, B2 and B3 respectively corresponding to Examples 1, 2 and 3 are prepared. previously detailed).

1. 1) formation de la couche barrière L1 : deux trempes successives dans le premier bain d'élastomère ;
2. 2) formation de la couche intermédiaire L2 : deux trempes successives dans le second bain d'élastomère (bains B1, B2 ou B3) contenant la dispersion de la substance radio-opaque ; puis
3. 3) formation de la couche barrière L3 : deux trempes successives dans le premier bain d'élastomère ;

étant entendu que chaque étape de trempe a été immédiatement suivie d'une étape d'évaporation des solvants, d'abord à l'air libre, puis dans une étuve à 40°C, et ce jusqu'à évaporation complète du solvant.The multilayer elastomeric material was then prepared by successive quenching of a porcelain mold having the shape of a hand as follows:

1. 1) formation of the barrier layer L1: two successive quenchings in the first elastomer bath;
2. 2) formation of the intermediate layer L2: two successive quenchings in the second elastomer bath (baths B1, B2 or B3) containing the dispersion of the radio-opaque substance; then
3. 3) formation of the barrier layer L3: two successive quenchings in the first elastomer bath;

it being understood that each quenching stage was immediately followed by a step of evaporation of the solvents, first in the open air, then in an oven at 40 ° C., until complete evaporation of the solvent.

The characteristics of the materials M1, M2 and M3 thus obtained respectively by implementing a quenching step in the elastomer baths B1, B2 and B3 containing the dispersion of the radio-opaque substance to form an intermediate layer L2 are reported in the Tables I to III below: <b> TABLE I (Material M1 / Bath B1) </ b> Thickness (mm) Module M 100 (MPa) Volume fraction of Bi ₂ O ₃ in the L 2 layer (%) Mitigation 60 kV 80 kV 100 kV 120 kV 0.4 0.35 20 52% 48% 45% 37% Thickness (mm) M100 module (MPa) Volume fraction of Bi ₂ O ₃ in the L 2 layer (%) Mitigation 60 kV 80 kV 100 kV 120 kV 0.5 0.40 20 63% 57% 52% 46% Thickness (mm) M100 module (MPa) Volume fraction of Bi ₂ O ₃ in the L 2 layer (%) Mitigation 60 kV 80 kV 100 kV 120 kV 0.48 0.34 36 78% 70% 64% 60%

These materials in the form of gloves can then be directly used for hand protection against X-rays.

Claims (26)

Multilayer elastomeric material comprising at least two outer layers L1 and L3 trapping at least one intermediate layer L2, said intermediate layer being constituted by an elastomeric matrix comprising at least one dispersion of droplets of at least one composition containing at least one radio-opaque substance , said material being characterized in that the volume fraction φv of the radiopaque substance (s) within layer L2 is greater than or equal to 20% and in that said composition is liquid or gelled and that said radio substance -opaque is in the form of solid particles .. Material according to Claim 1, characterized in that it has a total thickness of between 300 μm and 3000 μm inclusive. Material according to Claim 1 or 2, characterized in that the thickness of each of the identical or different layers L1, L2 and L3 varies from 50 to 2500 μm. Material according to any one of the preceding claims, characterized in that the average diameter of the droplets of the composition containing the radio-opaque substance (s) is between 1 and 100 μm inclusive. Material according to claim 4, characterized in that the average diameter of the droplets of the composition containing the radio-opaque substance (s) is between 1 and 10 μm inclusive. Material according to any one of the preceding claims, characterized in that the elastomer (s) constituting the outer layers L1 and L3 as well as the intermediate layer L2, are preferably chosen from natural rubber, polybutadiene, polyisoprene and polychloroprene. polyurethanes, acrylic polymers or copolymers, silicone elastomers, SBR (Styrene Butadiene Rubber) copolymers , SBS (Styrene Butadiene Styrene), isobutene-isoprene copolymers such as butyl rubber, NBR ( Nitrile Butadiene Rubber ), x-NBR ( Carboxylated Nitrile Butadiene Rubber ), SIS ( Styrene Isoprene Styrene ), SEBS ( Styrene Ethylene Butylene Styrene ) and mixtures thereof; it being understood that the nature of the elastomer (s) constituting each of said layers may be identical or different from one layer to another. Material according to Claim 6, characterized in that the said elastomers are chosen from SIS (Styrene Isoprene Styrene) and SEBS (Styrene Ethylene Butylene Styrene). Material according to any one of the preceding claims, characterized in that at least one of the barrier layers L1 and L3 and / or the intermediate layer L2 contains, in addition, one or more plasticizing agent (s) or flexibilizer (s). Material according to Claim 8, characterized in that the plasticizing agent or agents represent from 5 to 500 parts per 100 parts of elastomer constituting the layer in which they are present. Material according to any one of the preceding claims, characterized in that each layer L1 or L3 results from the superposition of two or more sublayers of chemical nature, equivalent or otherwise. Material according to any one of the preceding claims, characterized in that the radio-opaque substance or substances are chosen from elements having an atomic number greater than or equal to 40. Material according to Claim 11, characterized in that the elements are chosen from bismuth, tungsten, barium, iodine, tin and their mixtures, said elements being in the form of metal particles, oxide or of salts. Material according to Claim 12, characterized in that the particle size of the radio-opaque substance or substances is between 0.5 and 50 μm inclusive. Material according to Claim 13, characterized in that the particle size of the radio-opaque substance or substances is between 0.5 and 5 μm inclusive. Material according to any one of the preceding claims, characterized in that the composition in the form of droplets further contains one or more diluents. Material according to Claim 15, characterized in that the diluent is chosen from glycerine, ethylene glycol and polyethylene glycols. liquid at room temperature or at a temperature in the region of room temperature and with a molar mass of between 62 and 750 Daltons inclusive. Material according to any one of the preceding claims, characterized in that the composition in the form of droplets containing the radio-opaque substance (s) is in gelled form and contains at least one gelling agent chosen from gelatin and polyesters. (ethylene oxide) semi-crystalline. Material according to any one of the preceding claims, characterized in that the intermediate layer L2 is formed of a superposition of two or more intermediate sub-layers each comprising a dispersion of droplets, the nature of the radio-opaque substances contained in each said sub-layers being identical or different from one sub-layer to another. Material according to any one of claims 1 to 17, characterized in that the intermediate layer L2 is formed by a single layer containing a dispersion of droplets containing radio-opaque substances different from one droplet to another. Material according to any one of the preceding claims, characterized in that the radio-opaque substance (s) can furthermore be directly dispersed, in addition to the droplets, in the matrix of the layer L2. Material according to any one of the preceding claims, characterized in that it is reinforced by an elastic textile web of natural or synthetic organic fibers serving as a support for one or both of the L1 and L3 layers. Material according to any one of the preceding claims, characterized in that it is in the form of aprons, gloves, finger cots, thyroid protectors or gonad guards. Use of at least one multilayer elastomeric material as defined in any one of the preceding claims for the manufacture of elastomeric radiation protection articles. Use according to claim 23, against X-rays, ionizing radiation and radiation used in radiotherapy. Use according to claim 23, against X and / or gamma rays. Use of at least one material as defined in any one of claims 1 to 22, for the manufacture of aprons, gloves, finger cots, thyroid protectors or gonad guards.

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