EP4048603A1

EP4048603A1 - Biodegradable stretch film

Info

Publication number: EP4048603A1
Application number: EP20807086.2A
Authority: EP
Inventors: Raphaël HAUMONT; Olesya STUKANOVA
Original assignee: Centre National de la Recherche Scientifique CNRS; Universite Paris Saclay
Current assignee: Centre National de la Recherche Scientifique CNRS; Universite Paris Saclay
Priority date: 2019-10-23
Filing date: 2020-10-23
Publication date: 2022-08-31
Also published as: FR3102485A1; JP2022553982A; CA3155945A1; FR3102485B1; US20240058258A1; WO2021079076A1

Abstract

The present invention relates to the field of stretch films used in the cosmetic and agri-food packaging sectors. More specifically, the present invention relates to a stretch film comprising konjac and carrageenan in a mass ratio of between 20/80 and 60/40. A stretch film according to the invention has advantageous properties for use as a biodegradable stretch cling film and cosmetic mask.

Description

BIODEGRADABLE STRETCH FILM

The present invention relates to the field of stretch films used in the field of cosmetics and food packaging. It relates more particularly to a stretch film based on konjac and carrageenan in a mass ratio of 20/80 and 60/40. A stretch film according to the invention exhibits advantageous properties for use as a cosmetic mask and biodegradable stretch food film.

State of the art

Various types of stretch film are known from the state of the art. The article by Brenner T. et al. (Rheology and synergy of / r-carrageenan / locust bean gum / konjac glucomannan gels; Carbohydrate Polymers 98 (2013) 754-760) describes different gels, some of which contain Konjac and carrageenans, and compares their rheology. In the Konjac and carrageenan gels studied, the carrageenan powder contains 14% KCI; these salts influence the properties of the gel.

Patent CN101298507 describes the preparation of a packaging film composed of material derived from biomass. The raw materials for making the film are KGM [(C20H32O16) n], carrageenan (C12H16SO10) n], glycerin (C3H803), sucrose fatty acid ester (C30O12H56) and water (H20 ).

CN108559276 describes an edible soluble film with added soybean fiber. This film consists of soybean fiber as the main raw material, to which sodium carboxymethylcellulose, glycerin, konjac gum, and carrageenan are added to the solution. This film contains between 0.5 and 0.8% by mass fraction of konjac gum and 0.5 and 0.6% by mass fraction of carrageenan.

Patent FR2963888A1 describes a particular cosmetic hydrogel comprising a gelling and thickening complex based on carrageenan, glucomannan and galactomannan. The hydrogel composition according to the invention optimally comprises between 0.2 and 2% of carrageenan by hydrated weight of the hydrogel composition, between 0.2 and 2% of glucommanan by hydrated weight of said composition, and between 0.2 and 2% of galactomannan by hydrous weight of said composition.

Among the stretch films described previously, some are used to make cosmetic masks. For example, document WO2006 / 053333 describes a cosmetic mask comprising an insoluble support and a gelled composition. The gelled composition is composed of two separate gels, one comprising a polymeric, water-soluble gelling agent and the other comprising a strengthening agent.

There are also 100% natural cosmetic masks based on bio-cellulose. However, cellulose is a very modified molecule, to which chains are added. in order to make it water soluble. Cellulose is therefore a transformed product and not completely natural.

At present, there is no 100% natural and biodegradable stretch film which has good elasticity and resistance properties.

Disclosure of the invention

The inventors have shown that the combination of konjacet with carrageenan makes it possible to obtain a gel with very advantageous properties in terms of elasticity and resistance, which can be stretched in the form of a film. These unique properties reflect the synergistic effect specific to the combination of konjac and carrageenan in proportions between 20/80 and 60/40.

Thus, the invention relates to a composition of biodegradable stretch film type comprising konjac and carrageenans in which:

- the konjac / carrageenan mass ratio is between 20/80 and 60/40 and

- the total mass percentage of konjac and carrageenans is between 0.5% and 2%.

The invention also relates to the use of this composition for the preparation of a patch for topical use as well as kits for topical use comprising such a stretch film composition.

The invention also relates to the use of this composition for the preparation of a biodegradable stretchable food film, as well as kits for the preparation of such a film.

Finally, the invention relates to a process for preparing a stretch film as defined above.

Advantages of the invention

The stretch film according to the invention has the advantage of being prepared only from unprocessed bio-based ingredients. The carrageenans coming from an alga, the konjac from a tuber, and the products not being transformed, the proposed film is 100% natural and free from any toxic product. It is fully biodegradable and compostable.

This stretchable film exhibits novel properties which are particularly suitable for use as a cosmetic mask or patch. These properties are achieved only through the combination of konjac and carrageenans in a defined ratio. In other words, no other component is necessary to obtain these properties, unlike the compositions generally known from the prior art. It can be used alone for its anti-drying properties and its freshness effect. Advantageously, a cosmetic composition is placed between the film and the skin.

The film constitutes a physical barrier vis-à-vis the outside world. Thus, the cosmetic composition deposited on the film is protected from oxidation during the time of contact with the skin. Vitamins or other molecules sensitive to oxygen can act optimally on the skin. The mask can be applied for several hours without drying out.

One of the problems which arises when a composition is applied to the skin is that it dries up during the dwell time, inducing unpleasant sensations of tightness and difficulties during removal. When the cosmetic composition is protected by the stretch film serving as a mask support, then it does not dry and the whole remains comfortable. An advantage associated with this configuration is that the amount of cosmetic composition can be reduced compared to a conventional application, which is economical. This is all the more true since the film does not absorb the cosmetic composition, unlike certain fabric mask supports.

Another advantage of the film is that it adapts perfectly to the morphology of the surface to which it is applied. It can be the shape of the face in the case of a cosmetic mask but also any other part of the body on which you want to apply a patch: ankle, knee, hand ... This adaptability results from a combined high elasticity good resistance to breakage. The properties of this film give it a "second skin" effect. Thus, the film exerts a certain surface pressure on the skin conducive to the diffusion of the active principles through the superficial layers of the skin.

Surprisingly, the film produces a persistent freshness effect. This effect is highly valued in many cosmetic and wellness applications. The freshness effect is interesting for a cosmetic mask, in particular for its decongestant effect (under the eyes for example), but also for well-being applications on sunburns, to calm the sensations of heavy legs ...

The properties of this film are also very advantageous for producing stretchable food films. Such films are intended to replace plastic films (polypropylene). Like the latter, the stretch films according to the invention form a film used to preserve foodstuffs against oxidation and thus to preserve their organoleptic properties.

It is therefore a biopolymer film for biodegradable and compostable food use, in other words a plant cover, as well as kits for preparing such a film.

These stretchable food films can be applied by resting on the edges of a container containing food or directly in contact with food. Being made of edible raw materials, they do not present any danger to health, even after prolonged direct contact with food. The advantages described above for cosmetic applications can also be used in the food industry. Indeed, thanks to its great stretchability, the film adapts perfectly to the shape of the food to be protected. It protects them from oxidation and dehydration for at least 24 hours, if not longer. It is easy to prepare and handle. Remember that it is compostable and biodegradable, like food waste.

The stretch film according to the invention can be in different forms. A presentation in powder form allows you to make the film yourself; the preparation does not present any difficulty. Indeed, it suffices to dilute a powder comprising a mixture of Konjac and carrageenans in an aqueous solution. The stretch film can also be presented directly in the form of a ready-to-use stretch film. Finally, the stretch film can be dehydrated and provided as a sheet to be hydrated in an aqueous solution at the time of use.

DETAILED DESCRIPTION OF THE INVENTION

A first subject of the invention relates to a composition of biodegradable stretch film type comprising konjac and carrageenans in which:

- the konjac / carrageenan mass ratio is between 20/80 and 60/40 and

- the total mass percentage of konjac and carrageenans is between 0.5% and 2%.

In a particular embodiment, the mass ratio between konjac and carrageenans is between 25/75 and 50/50; this ratio makes it possible to reconcile good elasticity and good resistance to stretching.

From the point of view of properties, the 35/65 ratio provides maximum synergy but this ratio can be modulated according to the applications.

Advantageously, a ratio of between 30/70 and 55/45, or even between 35/65 and 55/45, makes it possible to obtain properties suitable for an application as a stretch film.

For mask application, a ratio between 40/60 and 45/55, and each of these two ratios are particularly advantageous.

In a particular embodiment, a 60/40 ratio is possible when the solvent is distilled water.

For the purposes of the invention, the term “konjac” means a powder of Amorphophalus konjac, a vegetable in the form of a tuber cultivated in South-East Asia. It can be a whole flour obtained by grinding the tuber or glucomannan purified from konjac. Advantageously, the carrageenans used are Kappa or k-carrageenans carrageenans.

The physical properties of the film are based solely on the synergistic effect observed thanks to the mixture of konjac and carrageenan.

Thus, in a particular embodiment, the invention relates to a composition of biodegradable stretch film type containing konjac and carrageenans in which:

- the konjac / carrageenan mass ratio is between 20/80 and 60/40 and

- the total mass percentage of konjac and carrageenans is between 0.5% and 2%.

Other components can be added to the stretch film composition to impart additional properties to it without altering the elasticity and strength properties. Such components are for example maltodextrin, glycerin, a preservative, etc. In a particular embodiment, glycerin, an agent frequently used for its emollient, moisturizing and texturizing properties, in particular in cosmetics and in pharmacy, is added to the composition.

A stretch film composition according to the invention can be obtained by dissolving a powder comprising a mixture of konjac and carrageenans in the proportions defined above in an aqueous solution so that the total mass percentage of konjac and carrageenans is between 0.5 and 2%. Preferably, the total mass percentage of konjac and carrageenans is 1%.

By “aqueous solution” within the meaning of the invention, is meant for example water, in particular distilled water, a floral solution, an infusion of plants and / or fruits, but also sea water. .

In a particular embodiment of the invention, the aqueous solution is sea water. This variant makes it possible to prepare cosmetic masks and patches by benefiting from the richness in minerals, sought for example in thalassotherapy centers and products. derivatives.

The stretch film composition can be in a dehydrated form.

By “stretch film composition in dehydrated form” is meant, in the context of the present invention, a dry composition obtained by dehydration of a film exhibiting elasticity and resistance properties as defined above.

A stretch film composition in dehydrated form can more particularly be obtained by subjecting a stretch film comprising carrageenans and konjac as defined above to a dehydration process. Various dehydration processes are well known to those skilled in the art, namely for example drying at room temperature, heating, etc.

Such a dehydrated composition is intended to be rehydrated before use, for example by soaking in an aqueous solution. A second subject of the invention relates to the use of a composition as defined above as a patch for topical use.

The mechanical properties of this gel are quite suitable for application to the skin.

Used alone as a patch or mask, this film provides a feeling of freshness and hydration.

Used in combination with a cosmetic or well-being composition, it allows a “second skin” type application while preventing the composition from drying out and oxidizing. The feeling of tightness is avoided, the active ingredients are preserved and maintained in contact with the skin. In this case, the film can be considered as a support for topical application of a cosmetic or well-being composition.

A third subject of the invention relates to a kit for topical use comprising a composition as defined above and at least one ingredient for cosmetic use.

In a particular embodiment, the invention relates to a ready-to-use kit comprising a stretchable film, in hydrated or dehydrated form, and at least one ingredient for cosmetic or wellness use.

The ingredient for cosmetic or wellness use can be one or more ingredients to be diluted in a solution or be a cosmetic composition. The cosmetic or well-being ingredient or composition can be chosen from those known to those skilled in the art for their interest in cosmetics or for the well-being, such as a moisturizing agent, a vitamin, a vegetable oil, an essential oil. .... or any combination of these.

In practice, the user must first prepare the film and then spread the active principles thereon, for example using a brush.

A “well-being composition” can for example contain essential oils with soothing or stimulating properties, Bach Flowers or any other ingredient or composition which can act on physical or mental well-being.

When the kit contains a mask or a patch in dehydrated form, the kit may also include an aqueous solution for rehydrating the stretch film.

A fourth subject of the invention relates to the use of a composition as defined above as a biodegradable stretchable food film.

This involves using a composition according to the invention to prepare a stretchable food film.

A fifth object of the invention relates to a kit for the preparation of a biodegradable stretch food film. In a particular embodiment, the ready-to-use kit comprises a stretchable film, in hydrated or dehydrated form. When the kit contains a film in dehydrated form, it can also comprise an aqueous solution for rehydrating the stretch film and optionally a mold for casting the film.

A fifth subject of the invention relates to a process for preparing a composition as defined above, this process consisting in diluting a powder comprising at least one mixture of konjac and carrageenans in an aqueous solution, the konjac / carrageenan mass ratio being between 20/80 and 60/40 and the total mass percentage of konjac and carrageenans being between 0.5% and 2%.

The present invention will be better understood on reading the examples which follow, provided by way of illustration and should in no way be considered as limiting the scope of the present invention.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1. Example of experimental penetrometry curves obtained on Kj-K gels.

Figure 2. Evolution of the maximum penetration force as a function of the konjac fraction of the gel.

Figure 3. Evolution of the Young's modulus as a function of the konjac fraction of the gel.

Figure 4. Evolution of the elongation at break as a function of the konjac fraction of the gel.

Figure 5. Evolution of the maximum penetration force as a function of the konjac fraction of a gel containing 2% glycerin.

Figure 6. Protective effect against oxidation of a food film according to the invention deposited on the surface of the flesh of an avocado at t0, lh20, 2h50, 11h and 16h.

EXAMPLES

EXAMPLE 1: PREPARATION OF KONJAC / CARRAGHENANE GELS

The gels were made with distilled water or sea water (salinity of 30 g / L).

Various mixtures of konjac gum (Kj) and kappa carrageenan (K) were tested. We worked at 1% by total mass of texturizers. The ratio x = Kj / (Kj + K), - also called “fraction of konjac” hereafter - varies from 0 to 1.

Texturizers are dispersed in the water. The mixture is brought to 90 ° C. for 30 s with stirring. The gel is cast and then cooled at 8 ° C. for 12 h. The physical measurements are carried out at room temperature. EXAMPLE 2: GEL CHARACTERIZATION METHODS

In order to characterize the gels, texturometry measurements were carried out.

The physical measurements are carried out on an AmetekTA texturometer. The probe is a 12.6 mm diameter cylinder. The measurements are carried out in compression, up to 60% of the initial height of the sample.

The elastic modulus (Young's modulus), the maximum penetrating force as well as the elongation at break (if observed) are measured. Young's modulus and maximum force are expressed in gram-force (gf). The elongation at break is expressed in% relative to the initial length.

An example of a curve obtained is shown in Figure 1. The physical quantities extracted from the curves are indicated. Note: the dotted lines indicate parts of the curves that cannot be used (probe artefacts following sample breakage).

EXAMPLE 3: MECHANICAL PROPERTIES OF KONJAC / CARRAGHENANE GELS

Figures 2 and 3 show the maximum force and Young's modulus of the different gels as a function of the konjac fraction. a - Synergy of the Konjac-carrageenan mixture

The addition of konjac in a carrageenan gel greatly increases the mechanical properties. Indeed, it is observed that the Young's modulus doubles with an addition of only 10% Konjac gum. This underlines the synergistic character of the Konjac-carrageenan blend.

The synergy is also noticed by the non-linearity of the measurements. Young's modulus and elongation force increase when x <0.35, then decrease beyond this critical value. There is no proportionality between x and the physical quantities over the whole range 0 <x <1.

There is an estimated optimum value of x ~ 0.35 (distilled water) and x ~ 0.25-0.3 (sea water) for which the physical quantities go through maxima. This means that the synergistic effect is the most important and that the gels are the most elastic and resistant around this critical ratio.

The konjac-carrageenan synergy is very strong and particularly remarkable: a carrageenan gel containing 35% konjac (x = 0.35) is more than 10 times more resistant than a pure carrageenan gel (the Young's modulus goes from 5.7 to 65.1 with the addition of konjac). The force required to deform the gel is multiplied by more than 25 at this concentration range (90 vs 2400). Salt (NaCl), present in seawater, seems to decrease the physical properties of gels, even if the gels nevertheless have remarkable properties. The maximum synergy is slightly lowered towards low concentrations of konjac. b - Elongation at break of gels

Figure 4 shows the elongation at break of the gels.

While a pure carrageenan gel is “brittle” (elongation at break observed at approximately 20%) and not very resistant (low Young's modulus and low breaking force), the addition of konjac greatly increases this elongation: at -beyond the threshold value x ~ 0.35, the gel does not break (in the range of measurements carried out) and retains very high elasticity. We can associate this absence of rupture with "summerability". This underlines a very strong cohesion of the konjac-carrageenan chains under mechanical stress. The x ~ 0.35 value, again noted on this graph, once again demonstrates a maximum of synergy for this particular mixture. c - Properties of gels comprising glycerin

Glycerin was added to the composition in an amount of 2%.

The properties of this gel have been studied. The results are shown in Figure 5.

The optimum value is estimated at x = 0.30, that is to say at a value similar to that estimated for the gels prepared without glycerin. This result attests to the fact that the addition of an additional ingredient has only little influence on the properties of the gels and that the synergistic effect is therefore very specific for the konjac / carrageenan combination. d - Conclusion

When x changes from 0 to 1, gels with very diverse properties are obtained. These properties are easily modulated according to the value of x. Even if seawater or the addition of an ingredient such as glycerin alters these properties and displaces the maximum resistance, it is very easy to adapt the desired properties with x depending on the application medium:

• Low values of x: brittle, fragile, weak gel. This is characteristic of a carrageenan gel (but also gelatin gel, agar-agar etc ...)

• For 0.2 <x <0.6, the gels are very elastic, resistant and stretchable. A maximum of properties is observed around x ~ 0.35 in distilled water and x ~ 0.25-0.3 in sea water. The chemical konjac-carrageenan synergy explains these non-linear properties and the high values of the properties. measured physical quantities.

• High values of x: the gel is “sticky”, or even no longer forms beyond x ~ 0.7-0.8. A very viscous solution is obtained. This is characteristic of a pure solution of konjac gum (non-gelling thickener, just like, - but on a smaller scale - locust bean gum, guar gum, arabic gum etc ...)

EXAMPLE 4: THERMAL PROPERTIES OF GELS

In order to test their heat resistance and reversibility, konjac-carrageenan gels (with x = 0.3 and x = 0.5) were heated at 121 ° C, HOkPa for 35 min. The properties of the gels before heating and after heating / cooling were compared.

This experiment has shown that the properties of elasticity and resistance are recovered after cooling. It is therefore possible to sterilize the gels before packaging in order to allow their storage in a protected atmosphere.

EXAMPLE 5: FRESH EFFECT OF GELS

It has been observed that, deposited on the skin, the films described above provide a fresh effect, which persists for several tens of minutes. This feeling of cool / cold is independent of the temperature of the film since the film is initially at room temperature and at the temperature of the skin at the end of the experiment. The feeling of cool / cold is not related to excess humidity or water exuding from the gel by syneresis (water that vaporizes on the surface of the skin as a phenomenon known when a body comes out water for example). By comparison, pure gels of carrageenan, agar-agar, or even gelatin gels exhibit a much less marked and more ephemeral cooling effect.

EXAMPLE 6: PROTECTIVE EFFECT AGAINST OXIDATION

An avocado was cut into 2. On one of the halves, a 1mm thick carrageenan / konjac film (x = 0.4) was deposited, in direct contact with the flesh of the vegetable.

The oxidation reaction (polyphenol oxidases which react with oxygen to lead to brown pigments) has been observed over time.

The result of this experiment is shown in Figure 6.

We note that the chair is preserved from oxidation reactions for at least 16 hours. The oxidation reaction is therefore greatly slowed down in the presence of the film, which shows that the gel prevents the diffusion of oxygen. This is of major interest both in food and in cosmetics (where many organic active ingredients are unstable in air).

In addition, as observed in the photos of Figure 6, dehydration is considerably slowed down on the vegetable covered with the film. The initial volume (1/2 avocado) is preserved throughout the duration of the experiment (16h) for the part covered with the vegetable film, while for the part left in the open air, we notice a gradual decrease in volume and a "Stunting" of chairs. The film, rich in water, prevents the migration of water from the vegetable.

This experiment, carried out on an avocado, can be generalized to all foods (fruits, vegetables, fish, meat, etc.). Tests were also carried out using the film as a cover (use analogous to current plastic-based stretch films): the film is not in contact with the food but is stretched on the surface of a container containing the food. . The film dries over time in the refrigerator, but the food itself remains preserved from oxidation and dehydration for several tens of hours. Once removed, the film is compostable.

In conclusion, this experiment shows that the film makes it possible to preserve the freshness of food, in particular by avoiding surface oxidation and dehydration. Thus the film acts as a physical barrier making it possible to isolate, here a food, but in a cosmetic application, the surface of the skin, from the drying and oxidizing effects of the surrounding air.

Claims

1. A biodegradable stretch film type composition comprising konjac and carrageenans in which:

- the konjac / carrageenan mass ratio is between 20/80 and 60/40 and

- the total mass percentage of konjac and carrageenans is between 0.5% and 2%.

2. Composition according to claim 1 further comprising a component selected from maltodextrin, glycerin or a preservative.

3. Composition according to one of claims 1 or 2 in dehydrated form.

4. Use of a composition as defined in one of claims 1 to 3 as a patch for topical use.

5. Use of a composition according to one of claims 1 to 3 as biodegradable stretchable food film.

6. Kit for topical use comprising a composition according to one of claims 1 to 3 and at least one ingredient for cosmetic use.

7. Kit according to claim 6 wherein said at least one ingredient is chosen from a moisturizing agent, a vitamin, a vegetable oil and an essential oil.

8. Kit for the preparation of a biodegradable stretchable food film comprising a composition according to one of claims 1 to 3.

9. Kit according to one of claims 6 or 7 further comprising an aqueous solution for rehydrating said composition when the latter is in dehydrated form.

10. Process for preparing a composition as defined in one of claims 1 to 3 consisting in diluting a powder comprising at least one mixture of konjac and of carrageenans in an aqueous solution, the konjac / carrageenan mass ratio being between 20/80 and 60/40 and the total mass percentage of konjac and carrageenans being between 0.5% and 2%.