Method for manufacturing an object made from cellulosic fibers and object made from cellulosic fibers thus manufactured

Abstract

Title: Method for manufacturing an object based on cellulosic fibers and object based on cellulosic fibers thus manufactured The invention relates to a method for manufacturing an object based on cellulosic fibers and an object based on cellulosic fibers thus manufactured. The manufacturing process 10 is essentially such that it comprises the following steps: Mixing 12, with water, a dry material comprising at least between 80 and 99%, preferably between 90 and 99%, of cellulosic 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 cellulosic fibers with a dry matter concentration by weight of substantially between 10 and 70%, preferably between 20 and 50%. Without drying it, shaping the pulp 14 in a mold of the object to be manufactured. Drying 16, by thermocompression, the shaped pulp in the mold.Figure for the abridged version: Fig. 1.

Description

Title of the invention: Method for manufacturing an object made from cellulosic fibers and object made from cellulosic fibers thus manufactured technical field

[0001] The present invention relates to the manufacture of objects, particularly three-dimensional objects, made from cellulosic fibers. More specifically, the present invention relates to a method for manufacturing an object made from cellulosic fibers and to an object made from cellulosic fibers thus manufactured. STATE OF THE ART

[0002] Faced with environmental concerns and the proliferation of plastic packaging waste, new legislation is being put in place all over the world on single-use packaging, particularly in Europe with the application of the 2018 European directive on the subject.

[0003] New solutions must therefore be found to replace plastics, and these solutions must be just as efficient, but also recyclable, bio-based, and biodegradable. Only cellulose possesses these three properties. However, improvements are needed in the shaping and performance of cellulosic materials. Taking the example of a closure cap, a utensil, or a complex container, all currently prepared by plastic injection molding, the present invention typically aims to provide an alternative based on cellulosic fibers.

[0004] Cellulose fibers are widely used in the packaging industry. Besides paper and cardboard, a wet molded cellulose process has existed for many years, using highly dilute fiber suspensions (0.1-lwt%) that require a compression / suction step to remove some of the water present in the fiber mat. Furthermore, a dry molding process has recently emerged, allowing the production of a simple 3D object from a roll of paper transformed into an airlaid. However, as with the wet molded cellulose process, complex shapes requiring right angles, closed corners, or solid objects cannot be produced using these cellulose-based processes. Moreover, objects produced by dry molded cellulose cannot currently exceed 3 cm in depth.

[0005] Companies such as Nissha® or Paperfoam® offer cellulose injection solutions, which are more like cellulose composites with cellulose content ranging from 20 to 60% in addition to a polymer matrix of the starch or polyvinyl alcohol (PVOH) type and numerous additives.

[0006] There is a need for packaging products made from cellulosic fibers that are recyclable and recycled, bio-based and biodegradable, and whose manufacturing process is itself more environmentally friendly. The present invention aims to meet at least part of this need. SUMMARY

[0007] To achieve this objective, according to a first aspect of the invention, a method for manufacturing an object based on cellulosic fibers is provided, comprising the following steps: - Mix, with water, a dry material comprising at least between 80 and 99%, preferably between 90 and 99%, of cellulosic 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 a long molecular chain, or of a water-retaining polymer, so as to obtain a pulp based on cellulosic fibers with a dry matter concentration by weight of substantially between 10 and 70%, preferably between 20 and 50%, and even more preferably between 20 and 30%, - Without drying it, shape the clay into a 2D or 3D form in a mold of the object to be made. - Drying, by thermocompression, the shaped paste in the mold.

[0008] According to a second aspect of the invention, an object based on cellulosic fibers is provided, comprising or composed of: - cellulose fibres with a dry matter weight concentration between 80 and 99%, preferably between 90 and 99%, and - 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 dry matter weight concentration between 1 and 20%, preferably between 1 and 10%.

[0009] The object according to the second aspect of the invention constitutes, for example, a three-dimensional package. It is advantageously free of starch and / or polyvinyl alcohol (PVOH). BRIEF DESCRIPTION OF THE FIGURES

[0010] The aims, objects, features and advantages of the invention will become clearer from the detailed description of an embodiment thereof, which is illustrated by the following accompanying drawings in which:

[0011] [Fig-1] The [Fig. 1] represents a flowchart of an implementation method of the manufacturing process according to the first aspect of the invention.

[0012] [Fig.2] Fig.2 schematically represents a cross-section in a mode of production of an object based on cellulosic fibers according to the second aspect of the invention, the object taking the form of a container, and more particularly of a yogurt pot.

[0013] The drawings are given by way of example and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications. DETAILED DESCRIPTION

[0014] Before proceeding with a detailed review of embodiments of the invention, optional features that may be used in combination or alternatively are listed below:

[0015] According to an example of the first aspect of the invention, the mixing is carried out in a twin-screw extruder.

[0016] According to an example of the first aspect of the invention, the step of shaping the dough is carried out at room temperature.

[0017] According to an example of the first aspect of the invention, the dry matter to be mixed further comprises cellulose nanocrystals, nanofibrils or microfibrils at a concentration of between 0.01 and 50% by weight of dry matter, preferably from 1 to 20%.

[0018] 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 the manufactured object lighter, allows it to dry faster, and helps stabilize the object's dimensions.

[0019] According to an example of the first aspect of the invention, the step of shaping the dough is carried out by injection.

[0020] According to an alternative example to the previous one, the step of shaping the dough is carried out by transfer molding.

[0021] According to an example of the first aspect of the invention, the cellulosic fibers to be mixed are derived from paper pulp.

[0022] According to the preceding example, the water-soluble polymer, preferably natural, or the water-retaining additive may be chosen from: Cellulose ethers (HPMC, HEC, HPC, CMC) - a synthetic polymer (e.g., polyethylene glycol, polyvinyl alcohol), - guar gum, locust bean gum, xanthan gum, - alginate, agar-agar, carrageenans, - pectins or hemicelluloses, - Functionalized or unfunctionalized cellulose nanocrystals or nanofibrils, and - mixtures thereof.

[0023] By way of example, at least one conventional additive in the field of papermaking and molded cellulose can be added to the formulation, which can, for example, be chosen from: - mineral fillers, - hydrophobic additives such as wax, drying oils or polymer emulsion, for example, - additives for functionalizing cellulose fibers such as AKD (Alkyl Ketene Dimer), rosin resin, or ASA (Alkenyl Succinic Anhydride), for example, - a wet-state resistance agent, and - their mixtures.

[0024] 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.

[0025] 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 escape in the form of water vapor.

[0026] According to an alternative or complementary example to the previous 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 vapor through the perforations of said at least one element.

[0027] According to an example of the first aspect of the invention, the shaping dough is free of starch and / or polyvinyl alcohol (PVOH).

[0028] A paste based on a material A is understood to be a paste comprising that material A and possibly other materials.

[0029] A parameter "approximately equal to / greater than / less than" a given value means that this parameter is equal to / greater than / less than the given value, to within 20% or 10% of that value. A parameter "approximately between" two given values ​​means that this parameter is at least equal to the smaller of the given values, to within 20% or 10% of that value, and at most equal to the larger of the given values, to within 20% or 10% of that value.

[0030] The first aspect of the invention relates to a method for manufacturing 10 an object 1 based on cellulosic fibers is described below with reference to [Fig.1].

[0031] This process is essentially such that it comprises the following steps: - Mix 12, with water, a dry matter comprising at least between 80 and 99%, preferably between 90 and 99%, of cellulosic 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 cellulosic fibers with a dry matter concentration by weight of substantially between 10 and 70%, preferably between 20 and 50%, and even more preferably between 20 and 30%, - Without drying it, shape the dough into a mold (14) of the object to be made. - Dry the shaped paste in the mold by thermocompression.

[0032] The water-soluble polymer, preferably natural, or the water-retaining additive allows the paste from the mixture to be injected or molded by transfer.

[0033] The mixture 12 is preferably made in a twin-screw extruder, to ensure good homogeneity of the paste.

[0034] The step of shaping the dough 14 can advantageously be carried out at room temperature (typically between 20 and 30°C), thus limiting the heat balance of the manufacturing process.

[0035] The fibrous network of the manufactured object 10 can be reinforced by adding cellulose nanocrystals, nanofibrils, or microfibrils to the dry material to be mixed 12 at a concentration of between 0.01 and 50% by weight of dry matter. More specifically, a paste of cellulose nanofibrils or microfibrils at a concentration of between 0.01 and 50% by weight of dry matter can be added to the inlet of the twin-screw extruder, for example, during a second pass of the paste to be mixed 12 through the twin-screw extruder.

[0036] 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 faster and helps stabilize the dimensions of the object.

[0037] The step of shaping the pulp 14 is carried out by injection or transfer molding, i.e., by injection systems which, like the twin-screw extruder, are advantageously already present in industry. Injection or transfer molding of a concentrated cellulose fiber pulp advantageously makes it possible to obtain a much wider range of objects than existing processes. In a non-limiting manner, the manufactured object 10 can, for example, be a pre-formed cellulose container, such as a plate or a yogurt pot (see [Fig. 2]), a pre-formed cellulose utensil, such as cutlery, and a pre-formed cellulose cap, including one with a thread. More specifically, the mixture 12 can be injected into a mold at the outlet of the twin-screw extruder or subsequently by transfer molding.

[0038] The cellulosic fibers to be blended 12 can advantageously be derived from paper pulp or from any other cellulosic sources, in particular bio-based, such as the different types of paper pulp, softwood, hardwood, bleached, unbleached, fibers from annual plants such as flax, hemp, wheat straw but also agro-waste such as seaweed fibers, beet pulp, coffee grounds and / or their mixture.

[0039] 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.

[0040] More specifically, the preferably natural water-soluble polymer or water-retaining additive may be chosen from: Cellulose ethers (HPMC, HEC, HPC, CMC) - a synthetic polymer (e.g., polyethylene glycol, polyvinyl alcohol), - guar gum, locust bean gum, xanthan gum - an alginate, agar-agar, carrageenans, - pectins or hemicelluloses - Functionalized or unfunctionalized cellulose nanocrystals or nanofibrils - mineral fillers, such as water-retaining fillers - hydrophobic additives such as wax, drying oils or emulsion polymer for example - cellulose fiber functionalization additives such as AKD (Alkyl Ketene Dimer), rosin resin, or ASA (Alkenyl Succinic Anhydride), for example, and - their mixtures.

[0041] Specific molds and / or specific use of these molds may be necessary to carry out thermocompression drying.

[0042] 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.

[0043] As an alternative or in addition, the drying step 16 by thermocompression can be carried out using a heat press having at least one perforated element of so as to allow the evacuation of water in the form of vapor through the perforations of said at least one element.

[0044] It may also be necessary to finely control the parameters of the thermocompression. More particularly, 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.

[0045] It follows from the above that the manufactured object 1 can advantageously be entirely bio-based, biodegradable, recyclable and recycled in the paper / cardboard sector.

[0046] The invention is not limited to the embodiments previously described and extends to all embodiments covered by the invention.

Claims

Demands

1. A method for manufacturing (10) an object (1) based on cellulosic fibers comprising the following steps: • Mixing (12), with water, a dry material comprising at least between 80 and 99%, preferably between 90 and 99%, of cellulosic 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 a long molecular chain, or of a water-retaining polymer, so as to obtain a pulp based on cellulosic fibers with a dry matter concentration by weight of substantially between 10 and 70%, preferably between 20 and 50%, and even more preferably between 20 and 30%, • Without drying it, shaping the pulp (14) in 2D or 3D in a mold of the object to be manufactured, • Drying (16), by thermocompression, the dough shaped in the mold.

2. Manufacturing method (10) according to the preceding claim, wherein the mixing (12) is carried out in a twin-screw extruder.

3. A manufacturing process (10) according to any one of the preceding claims, wherein the step of shaping (14) the dough is carried out at room temperature.

4. A manufacturing process (10) according to any one of the preceding claims, wherein 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. A manufacturing process (10) according to any one of the preceding claims, wherein 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. A manufacturing method (10) according to any one of the preceding claims, wherein the step of shaping (14) the dough is carried out by injection.

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

8. A manufacturing process (10) according to any one of the preceding claims, wherein the cellulosic fibers to be mixed (12) are derived from paper pulp.

9. A manufacturing process (10) according to any one of the preceding claims, wherein the water-soluble polymer is natural and water-retaining.

10. A manufacturing process (10) according to the preceding claim, wherein the preferably natural water-soluble polymer or water-retaining additive can be selected from: • Cellulose ethers (HPMC, HEC, HPC, CMC) • a synthetic polymer (e.g., Polyethylene glycol, polyvinyl alcohol), • guar gum, locust bean gum, xanthan gum • alginate, agar-agar, carrageenans, • pectins or hemicelluloses, • functionalized or unfunctionalized cellulose nanocrystals or nanofibrils, and • mixtures thereof.

11. A manufacturing process (10) according to any one of the preceding claims, wherein 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. A manufacturing method (10) according to any one of the preceding claims, wherein the drying step (16) by thermocompression is carried out using a thermopress by opening it, then closing it, at least once, to allow the water to escape in the form of water vapor.

13. A manufacturing method (10) according to any one of the preceding claims, wherein the thermocompression drying step (16) 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.

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