Porous non-woven fabric used for making sterilization products

Abstract

Porous nonwoven fabric used for the manufacture of sterilization articles. Porous nonwoven fabric intended for the manufacture of sterilization articles, in particular preformed sterile barrier systems, comprising fibers formed at least partially of metallocene polypropylene, and between 0.1 and 1.4% titanium dioxide by mass relative to the total weight of the nonwoven fabric. Figure for the abbreviation: Fig. 1

Description

Description Title of the invention: Porous non-woven fabric used for the production of sterilization items Technical field

[0001] The present invention relates to non-woven materials used in the manufacture sterilization articles, and more particularly but not exclusively in the production of preformed sterile barrier systems. Prior art

[0002] To sterilize medical equipment (reusable or single-use), it is known to use preformed sterile barrier systems (pre-SBS) that meet certain standards, including ISO11607 (Packaging of medical devices) sterilized at the terminal stage) and NF EN 868, in particular part 9, which describes the requirements and test methods for non-woven materials based on non-polyolefins coated. These preformed sterile barrier systems can consist of a film polymer, in particular multilayer, classically based on Polypropylene (PP) and Polyethylene terephthalate (PET), and a porous non-woven material and implemented by heat sealing. One side of the pre-SBS is not sealed, in order to leave an opening for allow the introduction of the instrument to be sterilized.

[0003] = Once inserted, the preformed sterile barrier system can be sealed to hot at its opening, and the whole thing placed in a sterilization enclosure lization such as an autoclave or a sterilization chamber, where a sterilizing agent- lization is injected. This agent can be water vapor, formaldehyde, hydrogen peroxide (particularly excited by an electromagnetic field - we speak then sterilization by gas-plasma) or ethylene oxide. Sterilization can also be done by irradiation.

[0004] — The porosity of the non-woven fabric thus allows the sterilizing agent to penetrate into the system to sterilize its contents.

[0005] — When the instrument is to be used, the medical staff proceeds to open the system by separation of the non-woven and the polymer film; during this operation, it is desirable that no fibers of the non-woven fabric are lifted, in order to guarantee the asepsis of the packaging system. Indeed, lifting of fibers can lead to a risk of pollution of the operating field.

[0006] The sealing force between the polymer film and the non-woven fabric must therefore be sufficient to ensure the integrity of the sterile contents of the system and to resist under pressure pressure during sterilization cycles, but not too high to avoid a risk of tearing and release of fibers upon opening. Application GB2449418 describes the use of metallocene polypropylene (PP) to manufacture a porous nonwoven suitable for use in sterilizable packaging. No fillers other than fluorinated compounds, antistatic, coloring or antimicrobial agents are provided. Statement of the invention There is a need to further improve porous nonwovens used in the manufacture of sterilization articles, in particular preformed sterile barrier systems, in order to facilitate their opening by peeling while ensuring sufficient sealing force, good quality of the imprint left on the nonwoven and absence of tearing to guarantee asepsis. Summary of the invention The invention aims to meet this need and achieves this by proposing a porous nonwoven intended for the production of sterilization articles, in particular preformed sterile barrier systems, comprising fibers formed at least partially from metallocene polypropylene, and between 0.1 and 1.4% of titanium dioxide by mass relative to the total weight of the nonwoven. Thanks to the invention, the sealing forces can be adjusted. Thus, the peelability and the user's feeling when opening the sterile barrier system can be improved. The opening forces are constant and moderate, which guarantees ease of opening, no tearing of the nonwoven and maintenance of asepsis. The quality of the impression formed on the nonwoven when opening the sterile barrier system is also improved (the impression can be more homogeneous, whiter, without transparent areas (i.e., without transparency), and does not have raised fibers). Surprisingly, the claimed content allows to adapt and improve the sealing performance, while maintaining good mechanical performance and preserving asepsis. Indeed, a content greater than 1.4% by mass of titanium dioxide leads in particular to a significant reduction in tear resistance in the running direction, as well as to a reduction in tensile strength in the running and transverse directions. A content below 0.1% leads to a transparent imprint on the porous nonwoven, especially at sealing temperatures between 150°C and 160°C. In addition, the sealing forces are not adjusted, which can cause tears in the nonwoven, or lifting of fibers when opening the sterile barrier system. The nonwoven according to the invention meets the ISO 11607 and ISO 10993 standards. It also complies with the DIN 58953-6 standards (the latter describes the tests of microbial barrier properties for medical devices requiring sterilization), ASTM F2101 (a measure of bacterial filtration efficiency BFE), and ASTM F1608 (measures the ability of a porous material to prevent bacterial penetration). In the latter method, a completely impermeable control sample (bacterial penetration = 0) is exposed to one million cfu (colony forming units). The number 106 has a log value of 6. If a sample subjected to the same test as the control sample allows the penetration of 10* cfu (log 10 = 1), its LRV (Log Reduction Value) is 5 (6 — 1 = 5). Thus, the higher the LRV value, the more resistant the porous material will be to bacteria and microorganisms. According to one or more advantageous characteristics of the invention, considered in isolation or in combination: the non-woven fabric contains between 0.1 and 1% by mass of titanium dioxide, better between 0.4% and 1% by mass of titanium dioxide, even better between 0.4 and 0.6% by mass of titanium dioxide, the non-woven fabric is of the spunbond type, the non-woven fabric is devoid of any mineral filler other than dioxide titanium, in particular in an amount greater than or equal to 0.1% by mass, titanium dioxide is of average size in number between 100 and 1000 nm, the fibers are formed entirely, with respect to the material(s) polymer(s) which constitute(s) them, of metallocene polypropylene. The invention also relates, according to another of its aspects, to an article, in particular a preformed sterile barrier system, in particular a sterilization pouch, operating field, protective clothing or pocket for transporting active ingredient, comprising a non-woven fabric according to the invention, as defined above. The invention also relates, according to another of its aspects, to a method of closing an article according to the invention, in which the non-woven fabric is heat sealed onto a thermoplastic support. Sealing is preferably carried out at a temperature between 135°C and 165°C, better between 150°C and 160°C. Brief description of the drawings The invention may be better understood by reading the detailed description which follows, non-limiting examples of its implementation, and by examining the attached drawing, in which: [Fig.1] shows a front view, non-woven side, of an example of a pouch of sterilization according to the invention, [Fig.2] is a partial and schematic cross-section of the pouch, [Fig.3] is a table illustrating the mechanical characteristics of nonwovens obtained for different titanium dioxide contents, [Fig.4] is a table illustrating the measured sealing forces and others findings, for different sealing temperatures and different contents in titanium dioxide. Detailed description Figures | and 2 show an example of a sterilization pouch 1 according to the invention, comprising a porous non-woven fabric 2 heat-sealed onto a support film 3 made of non-porous thermoplastic material, based on polypropylene PP and PET. In [Fig. 1], we see the pouch sealed on a welding line 4 extending on three sides only, thus providing an opening 5 for the introduction of an instrument to be sterilized. The non-woven fabric is heat-sealed on the support along a closing line 6 after introduction of the instrument, then the pouch is put to sterilize. The pouch 1 has on the side opposite the opening 5 an area 7 where the non-woven fabric covers the support without being welded to it, so as to allow them to be grasped by the user's hands in order to move them apart when the pouch is opened by peeling. Sterilization of this sterile barrier system can be carried out using different methods: - by moist heat: the sterilizing agent is water vapor (temperature: 121°C — 134°C for 18 — 30 min, under pressure). - by ethylene oxide: temperature between 30 and 60°C, with a relative humidity higher than 30% for 16-18 hours with an ethylene oxide concentration of 200-800 mg / L). Ethylene oxide is a toxic agent, so a desorption period must be observed after sterilization. - by ionizing rays (gamma rays or beta sterilization or electron beam). - by formaldehyde: formaldehyde can appear in the form of gas. - by gas-plasma: use in the form of hydrogen peroxide gas (H,02) diffused in the enclosure and transformed into plasma by an electromagnetic field. Ions, free electrons, and numerous free radicals with very strong bactericidal activity are generated. This method allows sterilization at low temperature, and does not require desorption. PP metallocene For the purposes of the invention, the term "polypropylene" covers a propylene homopolymer, propylene copolymers obtained by copolymerization of propylene with at least one alpha-olefin type comonomer and derivatives of propylene homopolymer or functionalized propylene copolymers, in particular by grafting a reactive function following an interaction with maleic anhydride or acid. acrylic, such as maleated polypropylene. A copolymer can be block or random. Polypropylene (in any form) can be isotactic or syndiotactic. For the purposes of the invention, the term “metallocene PP” means a polypropylene obtained by metallocene catalysis. Polypropylene is made via metallocene catalysis rather than the Ziegler-Natta process (the use of this type of catalysis for the production of polyolefins is well known to those skilled in the art as described in patents US5571619, US5322728 and USS472775). The nonwoven is preferably made from metallocene polypropylene (PP) in accordance with the teaching of patent GB2449418. Metallocene PP has a generally quite narrow molecular weight distribution (MWD), preferably with an MWD value of less than 3, especially less than 2.5, and allows the production of fibers with an average diameter of less than 25 microns, and especially in the 10-20 micron range. The nonwoven obtained is formed by a spun bond technique, in a manner known per se. The formation of the metallocene polypropylene fibers can be carried out as described in application GB2449418 (this process is also described in documents US3821062, US3563838, US 20210301425 and US2019145032). Titanium dioxide (TiO2) is incorporated during the production of the polypropylene fibers, by mixing with the metallocene PP, in particular by dry mixing. The titanium dioxide is preferably in the form of a masterbatch. The PP used can in particular be Metocene HM5625 with a melt flow index equal to 30g / 10° measured at 230°C, under a weight of 2.16kg (according to standard ASTM D1238). According to the invention, the porous nonwoven may be subjected to a calendering step. During this calendering step, several parameters may vary, such as the temperature (typically around 130°C and 160°C), the speed (typically greater than 10m / min) and the pressure (typically greater than 30 bars). The mass content of titanium dioxide in the non-woven fabric is between 0.1 and 1.4%, preferably being around 0.5%. Such a content makes it possible to benefit from advantageous properties for the manufacture of the pouch, as will be detailed with reference to the tables in figures 3 and 4. Nonwoven fibers can have an average diameter ranging from 10 to 25 microns. Titanium dioxide can have a number average size ranging from 100 nm to 1 um. Comparative tests Different samples based on porous non-woven fabric composed of metallocene PP (Metocene HM5625) and TiO, (average diameter equal to 300 nanometers), and a laminated polymer film PET 12y / PP 40y were produced. The non-woven fabric has an average weight of 93 g / m² (measured according to ISO 536). 5 cm x 15 cm strips were prepared for each sample. The PP side of the PET / PP film was heat sealed onto the porous nonwoven. Film (PET / PP) - porous nonwoven pairs were heat sealed with a laboratory heat sealer, the sealing being carried out with the hot jaw against the PET side. Different welding temperatures were tested: 150, 155 and 160°C, at a constant pressure of 5 bars, for a time of 0.3s. The measurement of sealing forces is carried out on 10 samples, being carried out on a dynamometer according to the ASTM F88 / F88M-2021 standard (technique B). Tensile tests are carried out on a dynamometer according to standard ASTM D882-18, on 10 samples. Tear tests are carried out on 10 samples, on a dynamometer according to standard ASTM D1938-19. These film (PET / PP) - porous non-woven pairs sealed on a laboratory heat sealer also made it possible to study the quality of the impression upon opening. Pouches such as those shown in [Fig.1] were also produced on a FFS (“Form-Fill-Seal”) machine. 3 sealing temperatures were used: 150, 155 and 160°C and the speed was set at 15 pouches per minute. These pouches made it possible to evaluate the sensations upon opening as well as the quality of the impression. In the table in [Fig.3], we see that the tear resistance is significantly degraded for tests at contents of 1.5% or more, and that it passes through a relative maximum at 0.5%. In the table in [Fig.4], the sealing forces for different sealing temperatures and different titanium dioxide mass contents were compared. The results are also appreciated in the form of comments in the last 2 columns of the table in [Fig.4] For a content of less than 0.1%, a lack of whiteness of the impression can be observed, and the presence of a transparent appearance, for sealing temperatures equal to 150, 155 and 160°C. We observe an absence of "transparentization" after peeling, a good sensation on opening, while preserving asepsis, for titanium dioxide rates of 0.19, 0.27, 0.5 and 0.8%. The sensations upon opening are poor at a strength of 1.5%. The best results are obtained for contents of 0.27% and 0.5% by weight of titanium dioxide, at 155°C and 160°C. In fact, a very good sensation is observed at the opening as well as a homogeneous and white imprint, preserving asepsis, as well as very good mechanical performances (tear resistance in particular). Of course, the invention is not limited to the examples which have just been described. For example, the nonwoven according to the invention can be used in the manufacture of preformed sterile barrier systems such as sachets, breathable strip bags or hospital packaging sleeves, among other articles. Metallocene PP can be blended with at least one other thermoplastic, for example, polyethylene (low density, or linear low density), grafted or ungrafted, or polybutene, among other possibilities. The proportion of the other polymer(s) in the blend is chosen to maintain the desired properties.

Claims

Claims

1. Porous non-woven fabric intended for the production of sterilization articles, including preformed sterile barrier systems, comprising fibers formed at least partially from metallocene polypropylene, and between 0.1 and 1.4% titanium dioxide by mass relative to weight total non-woven.

2. Nonwoven according to claim 1, comprising between 0.1 and 1% by mass of titanium dioxide.

3. Nonwoven according to claim 1 or 2, comprising between 0.4% and 1% in mass of titanium dioxide.

4. A nonwoven according to any one of claims 1 to 3, comprising between 0.4 and 0.6% by mass of titanium dioxide.

5. A nonwoven according to any preceding claim, being of the spun-bonded type.

6. A nonwoven according to any preceding claim, being devoid of any mineral filler other than titanium dioxide, in particular in an amount greater than or equal to 0.1% by mass.

7. Nonwoven according to any one of the preceding claims, the titanium dioxide being of average size in number between 100 and 1000 nm.

8. A nonwoven according to any preceding claim, the fibers being formed entirely, with respect to the polymer material(s) which constitute(s) them, of polypropylene me- tallocene.

9. Article, in particular preformed sterile barrier system, in particular sterilization pouch, surgical field, protective clothing or pouch for transporting active ingredient, comprising a non-woven fabric according to any one of the preceding claims.

10. A method of closing an article according to claim 9, wherein the nonwoven is heat sealed onto a thermoplastic support.

11. A method according to claim 10, the sealing being carried out at a tem- temperature between 135°C and 165°C, better between 150°C and 160°C.

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