Method for manufacturing an object based on cellulosic fibres and object based on cellulosic fibres thus manufactured

Abstract

The invention relates to a method for manufacturing an object based on cellulosic fibres and to an object based on cellulosic fibres thus manufactured. The manufacturing method 10 is essentially such that it comprises the following steps: • mixing 12, with water, solids comprising at least 80 to 99%, preferably 90 to 99%, of cellulosic fibres, and 1 to 20%, preferably 1 to 10%, of a preferably natural water-soluble polymer or of a water-retaining additive so as to obtain a pulp based on cellulosic fibres with a solids concentration by weight of substantially 10 to 70%, preferably 20 to 50%; • without drying it, shaping the pulp 14 in a mould of the object to be manufactured; and • drying 16 the pulp shaped in the mould by thermocompression.

Description

[0001]

[0002] “Process for manufacturing an object based on cellulose fibers and object based on cellulose fibers thus manufactured”

[0003] TECHNICAL FIELD OF THE INVENTION

[0004] The present invention relates to the manufacture of objects, in particular three-dimensional objects, based on cellulose fibers. More particularly, the present invention relates to a method for manufacturing an object based on cellulose fibers and an object based on cellulose fibers thus manufactured.

[0005] STATE OF THE ART

[0006] Faced with environmental concerns and the proliferation of plastic packaging waste, new legislation is being put in place around the world on single-use packaging, particularly in Europe with the application of the 2018 European directive on the subject.

[0007] New solutions must therefore be found to replace plastics, and these solutions must be as efficient, but also recyclable, bio-sourced, and biodegradable. Only cellulose possesses these three properties. However, progress must be made in the shaping and performance of cellulosic materials. Taking the example of a closure cap, a utensil, or a complex container, all currently prepared using plastic injection molding, the present invention typically aims to provide an alternative based on cellulosic fibers.

[0008] Cellulosic fibers are widely used in the packaging industry. In addition to paper and cardboard, a wet molded cellulose process has existed for many years, using very dilute fiber suspensions (0.1-1 wt%) requiring a compression / suction step to remove some of the water present in the fiber mat. Furthermore, a dry molding process has recently been introduced, making it possible to obtain a simple 3D object from a roll of paper transformed into airlaid. However, just like the molded cellulose process, complex shapes requiring right angles, closed angles, or solid objects cannot be produced using cellulose using these processes. Furthermore, objects produced using dry molded cellulose cannot currently exceed 3 cm in depth.

[0009] Companies such as Nissha® or Paperfoam® offer cellulose injection solutions, which are cellulose composites with cellulose contents ranging from 20 to 60% in addition to a polymer matrix such as starch or polyvinyl alcohol (PVOH) and numerous additives.

[0010] There is a need to provide cellulosic fiber-based packaging products that are recyclable and recycled, bio-sourced and biodegradable, and whose manufacturing process itself would be more environmentally friendly. The present invention aims to meet at least part of this need.

[0011] SUMMARY OF THE INVENTION

[0012] To achieve this objective, according to a first aspect of the invention, a method of manufacturing an object based on cellulose fibers is provided, comprising the following steps:

[0013] - Mixing, with water, a dry matter comprising at least between 80 and 99%, preferably between 90 and 99%, of cellulose fibers and between 1 and 20%, preferably between 1 and 10%, of a water-soluble polymer, preferably natural and cold-soluble, and even more preferably of long molecular chain, or of a water-retaining polymer so as to obtain a pulp based on cellulose fibers at a concentration by weight of dry matter substantially between 10 and 70%, preferably between 20 and 50%, and even more preferably between 20 and 30%,

[0014] - Without drying it, put the dough in 2D or 3D shape in a mold of the object to be made,

[0015] - Dry the dough shaped in the mold by thermocompression.

[0016] According to a second aspect of the invention, there is provided an object based on cellulose fibers comprising or composed of:

[0017] - cellulosic fibers at a concentration by weight of dry matter of between 80 and 99%, preferably between 90 and 99%, and

[0018] - a water-soluble polymer, preferably natural and cold-soluble, and even more preferably of long molecular chain, or a water-retaining polymer and / or additive at a concentration by weight of dry matter of between 1 and 20%, preferably between 1 and 10%.

[0019] The object according to the second aspect of the invention constitutes, for example, a three-dimensional packaging. It is advantageously free of starch and / or polyvinyl alcohol (PVOH).

[0020] BRIEF DESCRIPTION OF THE FIGURES

[0021] The aims, objects, as well as the characteristics and advantages of the invention will emerge more clearly from the detailed description of an embodiment thereof which is illustrated by the following accompanying drawings in which:

[0022] Figure 1 represents a flowchart of an embodiment of the manufacturing method according to the first aspect of the invention.

[0023] Figure 2 schematically represents a section in an embodiment of an object based on cellulose fibers according to the second aspect of the invention, the object taking the form of a container, and more particularly of a yogurt pot.

[0024] The drawings are given by way of example and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily to the scale of practical applications.

[0025] DETAILED DESCRIPTION OF THE INVENTION

[0026] Before commencing a detailed review of embodiments of the invention, optional features which may optionally be used in combination or alternatively are set out below:

[0027] According to an example of the first aspect of the invention, the mixing is carried out in a twin-screw extruder.

[0028] According to an example of the first aspect of the invention, the step of shaping the dough is carried out at room temperature.

[0029] According to an example of the first aspect of the invention, the dry material to be mixed further comprises cellulose nanocrystals, nanofibrils or microfibrils at a concentration of between 0.01 and 50% by weight of dry material, preferably from 1 to 20%. According to an example of the first aspect of the invention, the dry material to be mixed further comprises at least one surfactant-type foaming agent at a concentration of between 0.01 and 10% by weight of dry material. Advantageously, this foaming agent makes it possible to make the manufactured object lighter, allows it to dry more quickly and makes it possible to stabilize the dimensions of the object.

[0030] According to an example of the first aspect of the invention, the step of shaping the dough is carried out by injection.

[0031] In an alternative example to the previous one, the step of shaping the dough is carried out by transfer molding.

[0032] According to an example of the first aspect of the invention, the cellulosic fibers to be mixed are derived from a paper pulp.

[0033] According to the previous example, the water-soluble polymer, preferably natural, or the water-retaining additive can be chosen from:

[0034] - cellulose ethers (HPMC, HEC, HPC, CMC)

[0035] - a synthetic polymer (e.g. Poly ethylene glycol, polyvinyl alcohol),

[0036] - guar gum, carob gum, xanthan gum,

[0037] - an alginate, agar-agar, carrageenan,

[0038] - pectins or hemicelluloses,

[0039] - functionalized or non-functionalized cellulose nanocrystals or nanofibrils, and

[0040] - their mixtures.

[0041] According to one example, at least one conventional additive in the field of papermaking and molded cellulose may be added to the formulation which may for example be chosen from:

[0042] - mineral fillers,

[0043] - hydrophobizing additives such as wax, drying oils or polymer emulsion, for example,

[0044] - cellulose fiber functionalization additives such as AKD (Alkyl Ketene Dimer), rosin resin, or ASA (Alkenyl Succinic Anhydride) for example,

[0045] - a wet strength agent, and

[0046] - their mixtures.

[0047] According to an example of the first aspect of the invention, the thermocompression drying step is carried out at a temperature substantially between 100 and 200°C, preferably substantially between 120 and 180°C, and / or at a pressure substantially between 1 and 40 MPa. According to an example of the first aspect of the invention, the thermocompression drying step is carried out using a thermopress by opening it, then closing it, at least once, to allow the water to be evacuated in the form of water vapor.

[0048] According to an alternative example to, or complementary to, the preceding one, the thermocompression drying step is carried out using a thermopress having at least one perforated element so as to allow the evacuation of water in the form of steam through the perforations of said at least one element.

[0049] According to an example of the first aspect of the invention, the shaping paste is free of starch and / or polyvinyl alcohol (PVOH).

[0050] A paste based on a material A means a paste comprising this material A and possibly other materials.

[0051] A parameter that is "substantially equal to / greater than / less than" a given value means that this parameter is equal to / greater than / less than the given value, within plus or minus 20% or even 10% of this value. A parameter that is "substantially between" two given values ​​means that this parameter is at least equal to the smallest given value, within plus or minus 20% or even 10% of this value, and at most equal to the largest given value, within plus or minus 20% or even 10% of this value.

[0052] The first aspect of the invention relating to a method 10 for manufacturing an object 1 based on cellulosic fibers is described below with reference to FIG. 1.

[0053] This process is essentially as it includes the following steps:

[0054] - Mixing 12, with water, a dry matter comprising at least between 80 and 99%, preferably between 90 and 99%, of cellulose fibers and between 1 and 20%, preferably between 1 and 10%, of a water-soluble polymer, preferably natural, or of a water-retaining additive so as to obtain a pulp based on cellulose fibers at a concentration by weight of dry matter substantially between 10 and 70%, preferably between 20 and 50%, and even more preferably between 20 and 30%,

[0055] - Without drying it, put the dough in shape 14 in a mold of the object to be made,

[0056] - Dry 16, by thermocompression, the dough shaped in the mold.

[0057] The preferably natural water-soluble polymer or water-retaining additive has the effect of enabling injection or transfer molding of the paste from the mixture 12.

[0058] The mixture 12 is preferably carried out in a twin-screw extruder, to ensure good homogeneity of the dough. The step of shaping 14 the dough can advantageously be carried out at room temperature (typically between 20 and 30°C), thus limiting the heat balance of the manufacturing.

[0059] The fibrous network of the manufactured object 10 can be reinforced by adding, to the dry material to be mixed 12, cellulose nanocrystals, nanofibrils or microfibrils at a concentration of between 0.01 and 50% by weight of dry material. More particularly, a paste of cellulose nanofibrils or microfibrils at a concentration of between 0.01 and 50% by weight of dry material can be added at the inlet of the twin-screw extruder, for example during a second pass of the paste to be mixed 12 in the twin-screw extruder.

[0060] In addition or as an alternative, the dry material to be mixed 12 may further comprise at least one surfactant-type foaming agent at a concentration of between 0.01 and 10% by weight of dry material. Advantageously, this foaming agent makes the manufactured object lighter, allows it to dry more quickly and makes it possible to stabilize the dimensions of the object.

[0061] The step of shaping 14 the paste is carried out by injection or by transfer molding, i.e. by injection systems, which, like the twin-screw extruder, are advantageously already present in industries. The injection or transfer molding of a paste of concentrated cellulose fibers advantageously makes it possible to obtain a much wider range of objects than existing methods. In a non-limiting manner, the manufactured object 10 may for example constitute a preformed cellulosic container, such as a plate or a yogurt pot (see figure 2), a preformed cellulosic utensil, such as cutlery, and a preformed cellulosic cap, including one having a thread. More particularly, the mixture 12 may be injected into a mold at the outlet of the twin-screw extruder or subsequently by transfer molding.

[0062] The cellulosic fibers to be mixed 12 can advantageously come from a paper pulp or from any other cellulosic sources, in particular bio-sourced, such as different types of paper pulp, softwood, hardwood, bleached, unbleached, fibers from annual plants such as flax, hemp, wheat straw but also from agro-waste such as algae fibers, beet pulp, coffee grounds and / or their mixture.

[0063] Advantageously, the water-soluble polymer is natural and water-retaining. More specifically, it can be a natural water-retaining additive with lubricating properties. It can be derived from natural and renewable resources, or even from waste.

[0064] More particularly, the preferably natural water-soluble polymer or the water-retaining additive can be chosen from: - cellulose ethers (HPMC, HEC, HPC, CMC)

[0065] - a synthetic polymer (e.g. Poly ethylene glycol, polyvinyl alcohol),

[0066] - guar gum, carob gum, xanthan gum

[0067] - an alginate, agar-agar, carrageenan,

[0068] - pectins or hemicelluloses

[0069] - functionalized or non-functionalized cellulose nanocrystals or nanofibrils

[0070] - mineral fillers, such as water-retaining fillers

[0071] - hydrophobizing additives such as wax, drying oils or polymer emulsion for example

[0072] - cellulose fiber functionalization additives such as AKD (Alkyl Ketene Dimer), rosin resin, or ASA (Alkenyl Succinic Anhydride) for example, and

[0073] - their mixtures.

[0074] Specific molds and / or specific use of these molds may be necessary to carry out thermocompression drying.

[0075] For example, the drying step 16 by thermocompression can be carried out using a heat press by opening it, then closing it, at least once, to allow the water to escape in the form of water vapor.

[0076] Alternatively or in addition, the drying step 16 by thermocompression can be carried out using a heat press having at least one perforated element so as to allow the evacuation of water in the form of vapor through the perforations of said at least one element.

[0077] It may also be necessary to finely control the thermocompression parameters. More particularly, the thermocompression drying step 16 is carried out at a temperature substantially between 100 and 200°C, preferably substantially between 120 and 180°C, and / or at a pressure substantially between 1 and 40 MPa.

[0078] It is clear from the above that the manufactured object 1 can advantageously be entirely bio-sourced, biodegradable, recyclable and recycled in the paper / cardboard sector.

[0079] The invention is not limited to the embodiments previously described and extends to all embodiments covered by the invention.

Claims

CLAIMS 1. Method of manufacturing (10) an object (1) based on cellulose fibers comprising the following steps: • Mixing (12), with water, a dry matter comprising at least between 80 and 99%, preferably between 90 and 99%, of cellulose fibers and between 1 and 20%, preferably between 1 and 10%, of a water-soluble polymer, preferably natural and cold-soluble, and even more preferably of long molecular chain, or of a water-retaining polymer so as to obtain a pulp based on cellulose fibers at a concentration by weight of dry matter substantially between 10 and 70%, preferably between 20 and 50%, and even more preferably between 20 and 30%, • Without drying it, put the dough in a 2D or 3D shape (14) in a mold of the object to be made, • Dry (16), by thermocompression, the dough shaped in the mold.

2. Manufacturing method (10) according to the preceding claim, in which the mixture (12) is produced in a twin-screw extruder.

3. Manufacturing method (10) according to any one of the preceding claims, in which the step of shaping (14) the dough is carried out at room temperature.

4. Manufacturing method (10) according to any one of the preceding claims, in which the dry material to be mixed (12) further comprises cellulose nanocrystals, nanofibrils or microfibrils at a concentration of between 0.01 and 50% by weight of dry material, preferably from 1 to 20%.

5. Manufacturing method (10) according to any one of the preceding claims, in which the dry material to be mixed (12) further comprises at least one surfactant-type foaming agent at a concentration of between 0.01 and 10% by weight of dry material.

6. Manufacturing method (10) according to any one of the preceding claims, in which the step of shaping (14) the dough is carried out by injection.

7. Manufacturing method (10) according to any one of claims 1 to 5, in which the step of shaping (14) the dough is carried out by transfer molding.

8. Manufacturing method (10) according to any one of the preceding claims, in which the cellulosic fibers to be mixed (12) come from a paper pulp.

9. A manufacturing method (10) according to any preceding claim, wherein the water-soluble polymer is natural and water-retaining.

10. Manufacturing method (10) according to the preceding claim, in which the water-soluble polymer, preferably natural, or the water-retaining additive can be chosen from: • Cellulose ethers (HPMC, HEC, HPC, CMC) • a synthetic polymer (e.g. Poly ethylene glycol, polyvinyl alcohol), • guar gum, carob gum, xanthan gum • alginate, agar-agar, carrageenans, • pectins or hemicelluloses, • functionalized or non-functionalized cellulose nanocrystals or nanofibrils, and • their mixtures.

11. Manufacturing method (10) according to any one of the preceding claims, in which the drying step (16) by thermocompression is carried out at a temperature substantially between 100 and 200°C, preferably substantially between 120 and 180°C, and / or at a pressure substantially between 1 and 40 MPa.

12. Manufacturing method (10) according to any one of the preceding claims, in which the drying step (16) by thermocompression is carried out using a thermopress by opening it, then closing it, at least once, to allow the evacuation of the water in the form of water vapor.

13. Manufacturing method (10) according to any one of the preceding claims, in which the drying step (16) by thermocompression is carried out using a thermopress having at least one perforated element so as to allow the evacuation of water in the form of vapor through the perforations of said at least one element.

14. Object (1) based on cellulose fibers comprising or composed of: • cellulose fibers at a concentration by weight of dry matter of between 80 and 99%, preferably between 90 and 99%, and • a water-soluble polymer, preferably natural and cold-soluble, or a water-retaining polymer and / or additive at a concentration by weight of dry matter of between 1 and 20%, preferably between 1 and 10%.

15. Object (1) according to the preceding claim constituting a three-dimensional packaging.

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