WO2015004324A1

WO2015004324A1 - Method for producing a water soluble film and uses of the film

Info

Publication number: WO2015004324A1
Application number: PCT/FI2014/050553
Authority: WO
Inventors: Jari Vartiainen; Timo KALJUNEN; Harri SETÄLÄ
Original assignee: Teknologian Tutkimuskeskus Vtt
Priority date: 2013-07-09
Filing date: 2014-07-04
Publication date: 2015-01-15
Also published as: FI20135755L

Abstract

The present invention concerns production of water soluble xylan films in a large scale, where a mixture of xylan, glycerin and water is prepared by dissolving xylan in water, glycerin is added, and the mixture is cast on a moving web, the cast xylan film is dried, and the dried xylan film is separated from the moving web. Especially the invention concerns production of modified xylan films that are heat sealable for producing packages. The invention also concerns use of hydroxyalkylated xylan films for producing heat sealable packages.

Description

Method for producing a water soluble film and uses of the film

Technical Field

The present invention concerns production of water soluble xylan films in a large scale. Especially the invention concerns production of modified xylan films that are heat sealable for producing packages.

The invention also concerns use of hydroxyalkylated xylan films for producing heat sealable packages.

Background

Water soluble films have been used in the market for various purposes. Water soluble films may be used as packaging materials in portioning very precise dosages of any kind of dry powders, tablets or even non-polar liquids such as oils fats and greases. The package can be used for controlling the release of its contents at desired moment or place as release can be triggered by applying water on the package material. The pre-packed content is not in direct contact with skin during handling or the contact will is delayed until the film has dissolved in water. These types of water soluble pouches and encapsules can be found in detergent, food and pharmaceutical industry. Water soluble detergent pouches are probably the most widely known use of this technology. Water soluble films presently in use are e.g. polyvinyl alcohol (PVA) and ethylene vinyl alcohol (EVA). PVA is prepared by hydrolysis of polyvinyl acetate to remove acetate groups.

The water soluble film should be safe to user, environmentally safe and easy to form to packages. Biobased materials have such properties and provide several advantages as packaging material. Summary of Invention

At the moment biobased water soluble packaging materials have not been produced in large industrial scale. It would be beneficial to provide a method for producing thin films of biobased material that is water soluble and can be used for example in packaging. In a first aspect, the invention relates to a method producing a biobased water soluble film.

One embodiment of the invention relates to producing a water soluble film that is heat sealable.

According to other aspects and embodiments of the present invention, the invention provides method for producing a water soluble, heat sealable film of modified hydroxyalkylated xylan. According to one further aspect of the invention, modified xylan, is such as hydroxyl propylated xylan (HPX), butylated xylan (XI 5B) or 3-butoxy-2-hydroxypropyl xylan (BHPX).

According to further one aspect of the invention, the invention provides a method for producing a film from a modified xylan dissolved in water. The invention is based on casting a mixture of modified xylan and water on a moving web, drying the cast xylan film and separating the dried xylan film from the moving web.

According to one embodiment, the moving web is preferably a polypropylene film or alternatively some other synthetic plastic film with similar surface properties (such as polyethylene, polyethylene terephtiiaiate etc.). According to one embodiment of the invention, the polypropylene film is was pre-activated using physical activation.

According to one embodiment of the invention, the physical activation method is such as plasma, corona or UV.

According to one embodiment of the invention, the xylan film is separated from the polypropylene film by peeling and both films are wound on separate rolls.

The invention provides essential benefits. Xylan is one of the most abundant naturally occurring carbohydrates, but it has not been used in industrial applications. Xylan can be isolated from many agricultural by-products of forest and food industry. The production of xylan is based on renewable natural resources and therefore using xylan decreases demand of non-renewable resources like oil. By chemical modification the film forming properties and technical properties of xylan may be improved and tailored to meet various specific requirements. By the invention modified xylan solution can be easily formed into large scale films with varying thickness (10 - 100 μιη). The film, for example a film having thickness of about 100 μιη, can be heat sealed fast at about 100 °C. Seal strength (cold tack) may be as high as 800 N/m. Separate pouches can be easily produced from the films and pouches disintegrate and completely dissolve in water in less than 60 seconds. The films dissolve in water faster and more complete as compared for example to PVA films with the same thickness. The material is non-toxic and safe to handle by users and its environmental stress is low.

Other objects and features of the invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are intended solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims.

Description of Drawing

Fig. 1 shows an arrangement for producing a film according to the invention.

Description of embodiments Production of xylan films Methods Modified xylan, such as hydroxyl propylated xylan (HPX) or butylated xylan (XI 5B) or 3- butoxy-2-hydroxypropyl xylan (BHPX), was dissolved in water. The solids content of the mixture is 10 - 20 % of dry matter in solution, for example. Glycerin was added as plasticizer. For example, for HPX the HPX:glyserin ration can be 4: 1. Solution was homogenized with gentle mixing at ambient conditions to minimize the amounts of air bubbles. Solution was cast onto moving web, cast-polypropylene film (cPP) which was pre-activated using physical activation, atmospheric Ar/N2-plasma (100 W/m²/min). Well-controlled application of solution was performed with a feeding head where xylan formed an even and uniform layer with controlled thickness. Spreading and adhesion between the cPP and the aqueous film forming solution was fixed by adjusting physical pre-activation parameters such as activation time and power. After drying, the self-standing xylan film was finally delaminated from the cPP film and rewound into rolls.

The above described method can be carried out by an apparatus shown diagrammatically in Figure 1. The first step is to unwind a casting support that is made of cPP. The cPP film may be supported by any suitable rigid support, such a s cardboard layer, if needed. Unwinder is shown in drawing as section A. Downstream from unwinding follows section B where physical pre-activation of the cPP layer or film is made. Preferred activation method is plasma treatment, but corona discharge treatment may be used also. Spreading of the aqueous solution is performed on the following section, C. In this embodiment the spreading of the solution is made by casting solution on the cPP film . It can be contemplated that the spreading is performed by using methods known from paper industry or other coating applications, for example a by a film transfer coater or a short dwell time coater or even spray. Next the cPP film with a wet xylan layer is guided to dryer section D. In this embodiment air dryers are used, but any conventional that doesn't damage the supporting film can be used. After drying the cPP film with a solid xylan layer is guided to a delaminating section E wherein the xylan film is separated from the cPP film. The cPP film and xylan film may be wound on separate rolls and the cPP film can possibly be used again, or the xylan film and cPP film may be wound on a single roll so that the cPP film is used to protect the xylan film during storage and transport.

Examples:

Samples of xylan films were produced according to Table 1. Table 1. Production parameters of Xylan films

Results:

Production of xylan films according to the invention could be carried out with good quality.

Thus, while there have been shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the method and device may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same results are within the scope of the invention. Substitutions of the elements from one described embodiment to another are also fully intended and contemplated. It is also to be understood that the drawings are not necessarily drawn to scale but they are merely conceptual in nature. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.

Claims

1. Method for producing water soluble biobased film characterized by

- preparing a mixture of xylan, plasticizer such as glycerin and water by dissolving xylan in water, and adding glycerin

- casting the mixture of xylan, glycerin and water on a moving web,

- drying the cast xylan film, and

- separating the dried xylan film from the moving web.

2. Method according to the claim 1, characterized in that the moving web is a polypropylene film.

3. Method according to one of the claims 1 - 2, characterized in that the polypropylene film is was pre-activated before casting using physical activation.

4. Method according to one of the claims 1 - 3, characterized in that the polypropylene film is was pre-activated before casting using physical activation by atmospheric Ar/N₂ plasma.

5. Method according to one of the claims 1 - 3, characterized in that the polypropylene film is was pre-activated before casting using physical activation by corona or UV treatment.

6. Method according to one of the claims 1 - 5, characterized in that the xylan film is separated from the polypropylene film by peeling and both films are wound on separate rolls.

7. Method according to one of the claims 1 - 6, characterized in that the xylan that is dissolved in the water is modified hydroxyalkylated xylan.

8. Method according to one of the claims 1 - 6, characterized in that the xylan that is dissolved in the water is chosen from group of hydroxyl propylated xylan (HPX), butylated xylan (XI 5B) or 3-butoxy-2-hydroxypropyl xylan (BHPX).

9. Use of a hydroxyalkylated xylan films for producing heat sealable packages and water soluble packages.

10. Use of a hydroxyalkylated xylan films prepared from a group of hydroxyl propylated xylan (HPX), butylated xylan (XI 5B) or 3-butoxy-2-hydroxypropyl xylan (BHPX) for producing heat sealable packages and water soluble packages.