Patent Description:
The packages of the present disclosure are intended to be sterilized by suitable means, in particular and without limitation, steam, ethylene oxide, formaldehyde and/or gamma rays.

Two types of sterilizable packaging are available for the most part, especially at hospitals.

First of all, there are boxes or rigid containers made of metal. Due to their metallic nature, they can be particularly robust. However, these boxes have the drawback of their weight and they need to be washed regularly prior to use. Thus, this leads to a substantial handling of them, not to mention that the box eventually becomes worn out and develops leaks. The containers then need to be repaired, which leads to not insignificant costs.

There has been an effort to replace these boxes with disposable flexible packages of the pouch or sheet type. It is clear that these packages are easier to use on account of their weight and their disposable nature. However, they can have inadequate mechanical strength in regard to certain medical devices being sterilized. Furthermore, they are often manufactured from non-renewable resources, which is especially the case with the majority of those manufactured from polypropylene.

Document <CIT> describes a portable and disposable tray for surgical instruments. The tray is obtained by thermoforming of pulp. In practice, the instrument is stored in a sterilization bag and then positioned within the tray prior to the actual sterilization procedure. The properties of the tray make it permeable to the means of sterilization in the same way as the sterilization bag. The drawback of this system is thus the need for two elements, namely, a tray and a bag, which significantly increases the cost.

Document <CIT> describes a cellulose-based paper with a weight between <NUM> and <NUM>/m<NUM>. The paper is reinforced on one of its surfaces and has a sealing layer on the other surface, allowing the package to be closed by means of a film of polypropylene for example, after inserting the instrument to be sterilized. Thus, in this case there is no intermediate bag. The proposed paper has the major shortcoming of being excessively pliant, making it vulnerable when the instruments being sterilized have sharp edges.

Document <CIT> describes a sheet of calendered spunbond type, composed of fibers of polypropylene, thus not being biosourced and not being biodegradable.

Documents <CIT> and <CIT> disclose a sterilizable paper package for medical applications, comprising cellulosic fibers. These documents are silent about the maximum size of the pores of said fibrous structures.

To the knowledge of the Applicant, no disposable packaging rigid enough to make into trays, for example, has yet been proposed in hospitals for the sterilization of medical equipment.

Consequently, a problem which the present disclosure proposes to solve is to provide a rigid disposable packaging which is resistant to tearing, in particular, and which is ideally obtained from renewable and/or compostable components.

More precisely, an objective of the present disclosure is to provide a rigid disposable material which enables the sterilizing of instruments which are intended to be sterilized without having a risk of infection with microorganisms. Thus, it needs to be both permeable to the sterilization agent, which is in practice, for example, steam, ethylene oxide, formaldehyde, and gamma rays, and a barrier to bacteria.

Another objective of the present disclosure is to provide a rigid disposable material which complies with the standard ISO <NUM>-<NUM>.

To accomplish this, the Applicant has succeeded in producing a cardboard whose characteristics allow it to achieve at least partially the objectives of the aforementioned standard and whose weight allows it to be transformed into trays or any other rigid receptacle.

More precisely, the present disclosure relates to a sterilizable fibrous material for the packaging of medical devices intended to be sterilized. The sterilizable fibrous material is characterized in that: it is in the form of a cardboard having a basis weight of at least <NUM>/m<NUM>, advantageously at least <NUM>/m<NUM>; and it comprises a mixture of fibers containing at least <NUM>% by weight of natural cellulose fibers, the length of which is less than <NUM>; and it has a permeability to air of at least <NUM>, preferably at least <NUM>, advantageously strictly greater than <NUM>/Pa. s (µm per Pascal second) at a pressure of <NUM> kPa, measured according to the ISO <NUM>-<NUM> standard.

The greater the weight of the cardboard, the more rigid and easily transformable it is.

Thus, for example, the basis weight of the cardboard is advantageously at least <NUM>/m<NUM>, rendering it easily transformable, especially by thermoforming.

As previously mentioned, a major difficulty is to provide a sufficiently rigid material which is both permeable to the sterilization agent, such as steam, and barrier to bacteria.

In the present application, when reference is made to a standard, the applicable version is the one in force on the filing date of the priority application.

The Applicant has ascertained that particularly interesting performance is achieved in this regard when the mixture of fibers comprises: between <NUM>% and <NUM>% by weight of natural long cellulose fibers, the length of which is between <NUM> and <NUM>; and between <NUM>% and <NUM>% by weight of natural short cellulose fibers, the length of which is less than <NUM>.

The cellulose fibers are chosen, for example, from the group comprising pulp (short fibers and long fibers) and the fibers of annual plants, such as abaca, cotton, flax, and hemp.

Preferably, the long fibers have a length between <NUM> and <NUM> and preferably between <NUM> and <NUM> and the short fibers have a length between <NUM> and <NUM>, preferably between <NUM> and <NUM>.

In one particular embodiment, a portion of the cellulose fibers, preferably between <NUM> and <NUM>% by weight, is treated with soda in order to form mercerized cellulose fibers.

The performance of the material according to the present disclosure can be further improved when the mixture contains long fibers and short fibers, the ratio of long fibers to short fibers being between <NUM> and <NUM>.

In one preferred embodiment, the mixture of fibers contains between <NUM> and <NUM>% of long fibers and between <NUM> and <NUM>% of short cellulose fibers.

In order to increase the proportion of biosourced ingredients of the material of the present disclosure, the cellulose fibers represent at least <NUM>% by weight, preferably at least <NUM>% by weight, more preferably <NUM>% by weight and even more preferably at least <NUM>% by weight or even <NUM>% by weight of the weight of the material.

In one particular embodiment, the mixture of fibers further comprises between at least <NUM>% by weight, advantageously between <NUM> and <NUM>% by weight, of chemical fibers.

In practice, the chemical fibers have a titer between <NUM> and <NUM> dtex and a length between <NUM> and <NUM>, preferably between <NUM> and <NUM>.

When present, the chemical fibers are advantageously chosen from the group comprising artificial fibers such as Lyocell and rayon, and synthetic fibers such as biopolymers like polylactic acid, polyhydroxyalcanoate, polybutylene succinates, polybutylene succinate co-adipates, polycaprolactones, polybutyrate adipate terephthalate, poly(hydroxybutyrate-co-hydroxyvalerate) or their copolymers.

The Applicant has observed that the selection of a mixture of lyocell fibers, of preferably <NUM> dtex and <NUM> and/or of rayon, in particular Danufil (<NUM> dtex, <NUM> or <NUM>) made it possible to improve the permeability of the material.

Advantageously, the mixture of fibers is biosourced and/or recyclable and/or biodegradable.

Preferably, the material according to the present disclosure is biodegradable to a degree of <NUM>%, or even <NUM>%. Thus, the material meets the requirements of biodegradation of the standard EN <NUM>.

According to another characteristic and in certain embodiments, the material of the present disclosure has pores having a maximum pore diameter less than <NUM>, measured according to appendix C of standard EN <NUM>-<NUM>. The material may also have a mean pore diameter also known as average pore diameter less than <NUM>, preferably between <NUM> and <NUM>, measured according to appendix C of standard EN <NUM>-<NUM>. These characteristics thus allow it to comply with standard ISO <NUM>-<NUM>. The material can likewise comply with the standards of series EN <NUM>. It is noted that when tested in accordance with Annex C of standard EN <NUM>-<NUM>, the average of the pore diameters of the ten test pieces should be lower than or equal to <NUM>, and no pore diameter should be greater than <NUM>.

In practice, the material according to the present disclosure further comprises a wet strength agent, representing between <NUM> and <NUM>% by dry weight with respect to the dry weight of cellulose, preferably on the order of <NUM>%.

According to the present disclosure, the wet strength agent is chosen from the group comprising polyamine epichlorhydrin (PAE), glyoxalated resins, such as glyoxalated polyamide (GPAM), formaldehyde-based resin.

Preferably, the material according to the present disclosure further comprises a sizing agent representing preferably between <NUM> and <NUM>% by dry weight in relation to the dry weight of cellulose, preferably on the order of <NUM>%.

In practice, the sizing agent is chosen from the group comprising alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), and rosin-based resin.

In one preferred embodiment, the material further comprises cationic starch representing less than <NUM>% by dry weight in relation to the dry weight of cellulose, preferably on the order of <NUM>%.

According to the present disclosure, the material has hydrophobic properties, preferably measured according to the standard ISO <NUM> using a COBB test at <NUM> seconds, of less than <NUM>/m<NUM>.

Advantageously, it complies with the standard DIN <NUM>-<NUM> sections <NUM> and <NUM> in terms of bacterial barrier. The bacterial barrier properties can also be evaluated per the standard ASTM F2101. Thus, the material advantageously has a bacteria filtration efficacy (BFE) in a single layer greater than <NUM>%, preferably greater than <NUM>%, and more preferably greater than <NUM>%.

As previously mentioned, it advantageously complies with the standard ISO <NUM>-<NUM>.

According to another characteristic, the material has a thickness of at least <NUM>, preferably <NUM>, in order to give it optimal rigidity.

To render it heat-sealable, in particular when it is intended to be molded into a tray covered with a heat-sealable medical plastic film, said material further comprises a coating layer, the composition of which is able to render it heat-sealable.

The coating layer further allows limiting the surface roughness of the material and thus helps with the peelability of the film once it has been heat-sealed.

Advantageously, the coating contains at least one component chosen from among starch, polyvinylic alcohol (PVA), alkyl ketene dimer (AKD). The coating may further contain other components, such as bonding agents of the acrylic type, for example, or cross-linking agents, such as salts of zirconium and polyamine epichlorhydrin (PAE), for example.

In practice, the coating is applied at a rate of <NUM> to <NUM>/m<NUM>, preferably around <NUM>/m<NUM>.

In order to further improve the heat sealability, the material is calendered after the coating.

The present disclosure also relates to a tray or an equivalent receptacle obtained from the material described above.

The present disclosure also relates to the use of the previously described material for the fabrication of a tray.

Preferably, the tray is obtained by thermoforming.

In order to improve the thermoforming ability of the material of the present disclosure, it has a moisture level of at least <NUM>% by weight.

In order to avoid the risks of tearing during the thermoforming, the elongation of the material in the machine direction (MD) and the cross-machine direction (CD), preferably determined according to the standard ISO <NUM>-<NUM>, is at least <NUM>%.

The present disclosure also relates to a packaging for medical sterilization, comprising: a tray as previously described, or any equivalent means; and a means of tight sterilizable closure of the tray, such as a medical film of PET, PP or any other heat-sealable or gluable means.

The exemplary embodiments disclosed herein are illustrative of advantageous sterilizable packages, and systems of the present disclosure and methods/techniques thereof. It should be understood, however, that the disclosed embodiments are merely exemplary of the present disclosure, which may be embodied in various forms. Therefore, details disclosed herein with reference to exemplary sterilizable packages and associated processes/techniques of assembly and use are not to be interpreted as limiting, but merely as the basis for teaching one skilled in the art how to make and use the advantageous sterilizable packages and/or alternative sterilizable packages of the present disclosure.

Four samples were fabricated, the compositions of which are given in Table <NUM>:.

This was a spunbond composed of fibers of polypropylene and polyolefin with a basis weight of <NUM>/m<NUM> marketed by AMCOR <NUM> under the brand name ULTRA®.

The major characteristics of the different samples are given in Table <NUM>.

Samples <NUM> to <NUM> were compliant with the standard ISO <NUM>-<NUM>.

Sample <NUM> was calendered (<NUM> kN/m at <NUM>) and subjected to a heat sealing test with a medical film using Brugger clamps at <NUM>° C with a force of <NUM> bars for <NUM> seconds. No tear-off of fibers was observed and the seal showed a value greater than <NUM> N/<NUM>.

Sample <NUM> was thermoformed to produce a tray. The tray was sealed with a medical film for sterilization by steam or ethylene oxide made of PP/PET. An aqueous solution with a blue dye and a surfactant was injected in the tray. The colored solution was moved to the area of the sealing points on each side and maintained for <NUM> seconds each time, for a total duration of <NUM> seconds per the standard ASTM F <NUM>. No leak was observed (see <FIG>). Following the standard EN <NUM>-<NUM>, calendered sample <NUM> was subjected to a heat sealing test as with a medical film using Brugger clamps at <NUM> with a force of <NUM> bars for respectively <NUM>, <NUM>, <NUM> and <NUM> seconds. All samples had a peel strength greater than <NUM> N/<NUM> but remained less than <NUM> N/<NUM>. This showed that a tray according to the present disclosure can be properly sealed with a medical film and be opened without significant effort and without fibers tearing. As shown in <FIG>, the tray extends from a first end to a second end (from left to right), and extends from a first side to a second side (from the top of <FIG> to the bottom of <FIG>). The first end includes a first end wall, and the second end includes a second end wall. The first side includes a first side wall, and the second side includes a second side wall. The first and second end walls and the first and second side walls define a recess or cavity within the internal boundaries of the first and second end walls and the first and second side walls (e.g., with the recess/cavity housing the dye mixture), with a bottom wall at the bottom of the recess/cavity.

Sample <NUM> was thermoformed to produce a tray. The tray was then sealed with a medical film for sterilization by steam or ethylene oxide made of PP/PET, and then sterilized with steam for <NUM> at <NUM>° C. An aqueous solution with a blue dye and a surfactant was then injected in the tray. The colored solution was moved to the area of the sealing points on each side and maintained for <NUM> seconds each time, for a total duration of <NUM> seconds per the standard ASTM F <NUM>. No leak was observed (see <FIG>).

The purpose of this test was to show the ability of the material of the present disclosure to let the sterilizing steam pass through it, thus allowing a sterilization of the elements contained in it.

To do this, a tray was fabricated from sample <NUM>. On this tray was arranged <NUM> metallic pieces contaminated with microorganisms contained in saliva. The tray was then heat sealed with a film for sterilization by steam or ethylene oxide made of PP/PET. The tray was then sterilized with steam at <NUM> for <NUM> minutes. The tray was stored under normal conditions of pressure and temperature for <NUM> days prior to microbial analysis of <NUM> metallic pieces, chosen at random from the <NUM> pieces.

The microbial contamination was evaluated by the method ISO <NUM>-<NUM> and was based on a counting of bacteria and fungi. The medium used to culture the bacteria was Tryptic Soy Agar with an incubation of <NUM> at <NUM>. The medium used to culture the fungi was PDA with an incubation of <NUM> days at <NUM>.

The results show that, after sterilization, the metallic pieces are no longer contaminated, which proves that the material of the present disclosure is permeable to the sterilizing steam and remains sterile after a storage at room temperature for <NUM> days. This test also showed the mechanical strength of the tray (see <FIG>). In fact, it was possible to sterilize <NUM> metallic pieces weighing more than <NUM> and store them in sterile manner without any tearing or opening.

The test was performed on the <NUM> samples (samples <NUM>-<NUM>) according to the present disclosure and one comparison sample under the conditions of the standard DIN <NUM>-<NUM>, section <NUM>. Basically, the test involved sterilizing each sample with steam at <NUM> for <NUM> minutes. Each sample was then inoculated with <NUM>µL of the microbe S. epidermidis on one surface. After drying, the opposite surface of the sample was placed in contact with a culture medium and incubated for <NUM> at <NUM>. The two surfaces of each sample were tested.

No colony was found on any of the samples of the present disclosure or the comparison sample. The test for bacteria resistance in humid conditions according to standard DIN <NUM>-<NUM>, section <NUM> was thus validated.

The test was performed on <NUM> samples (samples <NUM>-<NUM>) according to the present disclosure and one comparison sample under the conditions of the standard DIN <NUM>-<NUM>, section <NUM>. Basically, the test involved sterilizing each sample with steam at <NUM> for <NUM> minutes. Each sample was then inoculated with <NUM> of sand contaminated with endospores of B. Incubations were then done at <NUM> and <NUM> to create a flow of air through the contaminated sand and the sample as far as the agar plate. The samples were then incubated for <NUM> at <NUM>. The <NUM> surfaces of each sample were tested.

As expected, no colony was found on any of the samples of the present disclosure or the comparison sample. This was expected, inasmuch as the test in humid environment according to standard DIN <NUM>-<NUM> section <NUM> is challenging, water serving as the vector of contamination. The test for bacteria resistance under dry conditions according to standard DIN <NUM>-<NUM>, section <NUM> was thus validated.

This test was performed according to the standard ASTM F2101, using an aerosol of Staphylococcus aureus. This test expresses the ratio of the number of bacteria arrested per sample, divided by the number of bacteria sprayed onto the sample tested.

As shown by Table <NUM>, sample <NUM> has a BFE of <NUM>% as compared to the comparison sample, which has a BFE of <NUM>% for a packaging of <NUM> sheet and <NUM>% for a packaging of <NUM> sheets. The sample according to the present disclosure presents a more tortuous pathway for the microorganisms and thus minimizes the risks of contamination.

Breathability is the ability of a material to allow water vapor to pass through it while preventing liquid water from passing through it, and is expressed interchangeably as "water vapor transmission rate" (WVTR), or "moisture vapor transmission rate" (MVTR). Accordingly, the material of the present disclosure has an overall water vapor transmission rate (WVTR) of at least <NUM>/m<NUM>/day, preferably at least <NUM>/m<NUM>/day, and more preferably at least <NUM>/m<NUM>/day at <NUM> and <NUM> % relative humidity and as determined by the ISO <NUM> standard.

The WVTR of sample <NUM> and comparative samples were measured according to the ISO <NUM> standard, and the results are summarized in Table <NUM>.

The samples were measured following the ISO <NUM> standard and at <NUM> and <NUM>% relative humidity. The data shows that sample <NUM> has comparable WVTR to the comparative sample, while the basis weight of sample <NUM> is more than triple of the comparative sample. The material according to the present disclosure can thus be efficiently sterilized.

In order to verify the uniformity and efficiency of the vapor penetration, sample <NUM> was thermoformed into a tray and a Bowie and Dick test kit was placed in the tray. The tray was then sealed with a medical film and was subjected to a sterilization cycle (Bowie and Dick cycle: <NUM> minutes at <NUM>). After sterilization, the Bowie and Dick kit test showed efficient and uniform steam penetration.

Two of each sample <NUM> (second from top row, and bottom row of <FIG>) and comparative samples (top row, and one above the bottom row of <FIG>) were placed in frame and were introduced in a home composter. The samples were then visually inspected after one, two weeks and four weeks. As it can be seen in <FIG>, sample <NUM> has almost completely biodegraded after four weeks, whereas the comparative samples remained intact.

In order to form a rigid tray, the material according to the present disclosure had a higher stiffness compared to other sterilization materials such as pouches or sterilization wraps. The rigidity or stiffness of a material may be measured by determining the resistance to bending of the material following ISO <NUM>-<NUM> - Paper and Board - Determination of resistance to bending - part <NUM> : Taber Type tester Standard. The material according to the present disclosure may have a resistance to bending of at least <NUM> mN in MD and CD directions, preferably at least <NUM> mN and even more preferably at least <NUM> mN.

The resistance to bending of Sample <NUM> and comparative sample were measured in the machine direction (MD) and the cross-machine direction (CD) (see Table <NUM>, below) following the ISO <NUM>-<NUM> standard.

Claim 1:
A sterilizable fibrous material for the packaging of medical devices intended to be sterilized, characterized in that:
the sterilizable fibrous material is in the form of a cardboard having a basis weight of at least <NUM>/m<NUM>, advantageously at least <NUM>/m<NUM>; and
the sterilizable fibrous material comprises a mixture of fibers containing at least <NUM>% by weight of natural cellulose fibers, the length of which is less than <NUM>; and
the sterilizable fibrous material has a permeability to air of at least <NUM>, preferably at least <NUM>, advantageously strictly greater than <NUM>/Pa.s at a pressure of <NUM> kPa, measured according to the ISO <NUM>-<NUM> standard; and
the sterilizable fibrous material has pores having a maximum pore diameter less than <NUM>, measured according to appendix C of standard EN <NUM>-<NUM>.