EP0987089B1 - Method for making shaped objects from a vegetable raw material by pressing - Google Patents

Abstract

For the production of biodegradable, compostable and recycling products, the material is a cake of sunflower or rape seed with an oil content of ≤ 20% and a protein content of ≥ 15%. It is wetted to give a moisture content of 5-55%. The cake is shaped in a press, with a mold of the product design. The molded material is heat dried, to stabilize it. The moisture content of the material is 10-25%, for heat shaping by pressure of 15-25 MPa at a temp. of 130-200 degrees C. The sunflower or rape seed material is initially given a mechanical treatment to break it down into homogenized granules with a mean diameter of 0.1-1.0 mm. The oil in the material is extracted partially, to give an oil content of ≤ 10% after drainage by trituration. The processed material is passed as a paste through a twin-screw extruder with, upstream to downstream, a chopper (8), a scraper (9), and if required, a bleed (11,12) for the liquid phase, and at least a reverse pitch module (10) to impose an axial compression on the solid matter, and an outlet (14). The twin-screw extruder has water injection (6,7) to set the moisture content of the material. The cake of sunflower or rape seed can be augmented by vegetable fibers.

Description

The invention relates to a method of manufacturing objects from vegetable raw material. It aims to make objects such as containers, packaging, panels or plates, in particular for the construction or furnishings, which, while benefiting from durability and stability compatible with their function, are biodegradable, compostable and recyclable. By "biodegradable" is meant that said object is likely to be degraded at least for the most part by microorganisms natural when put in the right conditions, without release of toxic products for the ecosystem, and at the scale of a few weeks to months. By "compostable" is meant an object which, divided, homogenized and mixed with organic matter and / or soil, provides a nutritious non-toxic substrate for plants. By "recyclable" is meant an object whose material can be reused to form an object of the same range.

Environmental constraints are growing severe, in particular for disposable products (in particular packaging) and packaging, and we are trying to manufacture these products by giving them a biodegradable and / or compostable and / or recyclable in order to prevent them become pollution or require expensive disposal treatments. Synthetic plastics generally meet the latter requirement but their recycling is expensive and requires prior sorting to separate the various types of materials, sorting which are not very compatible with the current lifestyle.

To limit these drawbacks, numerous studies have proposed to make objects using various plant materials such as wood fiber, sunflower hull, pulp and by combining these materials with binders, texturizers, synthetic glues or chemical reagents to obtain objects of good cohesion (US-5,593,625, US-5,663,221, Pat. Abstracts of Japan flight. 098 N004; JP 09327684). This solution does not fully resolve the problem of destruction of objects after use, due to the presence synthetic or other additives. In addition, synthetic binders and glues most common fail to release toxic products, or gradually over time (urea-formaldehyde, phenol-formaldehyde), either during manufacture or recycling (isocyanates). In some cases it is possible to make small common objects but the resistance properties obtained do not allow manufacture large objects or objects called to undergo significant constraints.

In addition, some publications have proposed replace synthetic binders with natural binders, especially gelatin (WO-96/14361). This type of process consists in mixing a vegetable load (essentially fibrous) and the natural binder to form a paste, and to be heated this in order to ensure the diffusion of the binder in the mass and the shaping of the product. The main shortcoming of this technique is its cost from essentially the cost of raw materials, which constitute extracted, finished or semi-finished products. In addition, the mechanical performance of materials made so far by this type of technique are poor (mechanical resistance comparable to that of cardboard).

In addition, certain lignocellulosic residues from oil extraction processes have been heat pressed to give them a cohesion and a certain mechanical resistance, but this remains poor, in particular the flexural strength of the products obtained.

The present invention proposes to overcome the disadvantages of known methods and to indicate a new method allowing to make a biodegradable, compostable and recyclable object in remarkable saving conditions.

Another object of the invention is to manufacture an object which has good flexural strength compatible with uses in construction, furniture, packaging, packaging ...

To this end, the manufacturing process according to the invention consists in (a) using a sunflower or rapeseed meal having a content weight by oil of less than 20% and a protein content by weight greater than 15%, hydrated so as to present a weight rate of hydration substantially between 5% and 55%, (b) press forming said cake in a shape adapted to that of the desired object and (c) to produce a heat treatment or drying treatment to ensure stiffening of the shaped object.

"Sunflower or rapeseed meal" means usual way the solid residue from oil extraction from sunflower seeds or whole or shelled rapeseed, whatever the means of extraction (pressing, solvent extraction ...), this oil extraction can be total or partial but lowering the oil content by weight of the product below a threshold generally around 20%; the meal may or may not have been the subject of a preliminary partial extraction of protein, its protein content by weight however, remaining above 15%. (All weight contents are expressed as a percentage relative to the weight of dry matter; the rate of hydration is expressed in relation to the total matter).

Experiments have shown that from of a raw material consisting of sunflower meal or brown crab rapeseed, suitably prepared to meet the conditions previously defined, it was possible to achieve, by a conventional forming process or thermoforming, shaped products, with excellent cohesion and remarkable resistance quality without the need to add a any adjuvant. Thus, the process of the invention is very economical since it is implemented from a natural raw raw material, very abundant, without the addition of finished or semi-finished, synthetic or natural products. It is completely unexpected that such a vegetable residue from sunflower or rapeseed, very heterogeneous and currently considered a low-value by-product (used only in animal feed to ensure a low intake energy value), allows to implement under conditions satisfactory a forming or thermoforming process for manufacturing an object of equivalent quality to that of thermoformed plastic objects synthetic. This remarkable result is explained a posteriori by the inventors by the composition of sunflower or rapeseed meal, which contains fibers and proteins, the latter having a suitable nature and content to diffuse and associate the fibers until constituting with them a matrix ready for forming. The hydration water of the oil cake used has a solvation of these proteins, the chains of which deploy to interact with fibers.

The method of the invention can be implemented by operating thermoforming of the cake, consisting of bringing it, during pressing, to a temperature substantially between 130 ° C and 200 ° C. In this case, we pre-adjust the hydration rate of the meal to a value between 5% and 25%. This value range allows good thermal transfers, a satisfactory deployment of protein chains, without excessive degassing likely to locally weaken the material. Preferably thermoforming is carried out at a pressure substantially between 15 and 25 megapascals. A such thermoforming process is faster than forming cold (discussed later) and leads to better mechanical resistance.

To further improve the cohesion and resistance of thermoformed objects and facilitate the implementation of thermoforming, oil cake sunflower or rapeseed is preferably subjected to a treatment mechanics of division and homogenization to give it a distribution particle size such that the median diameter of the particles D50 is substantially between 0.1 mm and 1 mm. By "median diameter D50", we means a diameter such that 50% of the particles by weight pass through a sieve vibrating with a mesh side equal to said diameter. (All measures particle size are carried out on the dry matter).

It is thus possible to produce, by thermoforming sunflower meal or rapeseed meal, panels usable in the construction, mainly consisting of plant fibers linked by proteins, having a flexural strength substantially between 10 and 25 megapascals.

According to another mode of implementation, the meal, previously subjected to a mechanical division treatment and homogenization to give it a particle size distribution such as median particle diameter D50 is less than 1mm, is hydrated, by a addition of water, at a hydration rate substantially between 25% and 50% in order to obtain a plastic paste which is then cold formed by pressing before being dried until hardening. The forming pressure can advantageously be adjusted between 1 and 5 megapascals. Such an implementation leads to a dough suitable for very easy modeling (modeling qualities equivalent to that of a plasticine) and allows to realize at very low price objects of very varied forms. However, the mechanical resistance of the objects obtained is lower than in the case of an implementation by thermoforming as previously mentioned.

Furthermore, it could be noted that the residual oil from the oil cake has an unfavorable effect on the forming and qualities of objects obtained, and an oil cake is advantageously used at least partially deoiled, with an oil content by weight of less than 10%. We can, the case if necessary, use an oil-depleted oil cake from the crushing of sunflower or rapeseed. (We generally mean by "exhausted cake in oil "a cake containing at most 2% oil). We limit or delete thus the hydrophobic repulsive forces which tend to oppose fiber / protein association.

The meal can in particular be divided and homogenized, and possibly at least partially de-oiled, by passing through a twin-screw device comprising, from upstream to downstream, shearing means, means crushing, means for withdrawing the liquid phase, at least one module not inverted to achieve axial compression of the solid materials, and a solids outlet, said twin-screw device being furthermore equipped with means water injection to adjust the hydration rate of the meal. Such treatment refines the texture of the meal and allows the association of fibers and proteins to be generated under optimal conditions during forming. In in addition, it makes it possible, if necessary, to provide additional deoiling of the meal.

Sunflower or rapeseed meal may if necessary be enriched with vegetable fibers in order to further lower the cost price of objects obtained. This method of implementation which makes it possible to value stocks existing low-value vegetable fibers (straw, sunflower shell) will be especially used when using a meal containing all its proteins original (without partial extraction) or when the object sought is not submitted to severe mechanical strength requirements.

The method of the invention makes it possible to manufacture objects of very diverse type: flat objects such as panels, plates, supports, spacers ..., hollow objects such as containers, packaging ...

The following examples are intended to illustrate the process of the invention.

• la figure 1 est une représentation longitudinale symbolique dudit dispositif bi-vis,
• la figure 2 en est une coupe transversale par un plan A,
• les figures 3, 4 et 5 sont des coupes verticales des dispositifs de moulage utilisés respectivement dans les exemples 1, 2 et 3.

In Example 1, the cake after deoiling by pressing of the traditional type is subjected to a preliminary preparation treatment in a twin-screw device; this twin-screw device and the molding devices for carrying out the forming or thermoforming in the examples are shown schematically in the accompanying drawings; on these drawings:

• FIG. 1 is a symbolic longitudinal representation of said twin-screw device,
• FIG. 2 is a cross section thereof through a plane A,
• FIGS. 3, 4 and 5 are vertical sections of the molding devices used respectively in Examples 1, 2 and 3.

The twin-screw device shown diagrammatically in Figures 1 and 2 is used to carry out the prior preparation of the cakes in Example 1; these measures is obtained from modules sold by the company "CLEXTRAL" (registered trademark) under the general reference "BC45". Each module includes a double-walled tubular enclosure 1 and 2 which allows thermal regulation from the heart of the enclosure where the active organs are housed. Some modules are type comprising two identical co-penetrating screws, others of the type comprising shear mixers composed of two-lobed discs. The various modules are rotated in synchronism by an electric motor 3 allowing obtain a speed of rotation of its output shaft which can reach 700tr / min. In the examples, the speed of rotation chosen is 100 rpm.

• une zone de convoyage et mise en pression Z₁, comprenant une trémie 4 d'alimentation en tourteaux, des modules de bi-vis à pas direct décroissants tels que 5, et un conduit 6 doté d'une pompe 7 pour l'injection d'eau,
• une zone de cisaillement Z₂ comprenant un ou des malaxeurs à disques bilobes tels que 8,
• une zone d'écrasement et mise en pression Z₃, combinant des modules d'écrasement constitués par des modules de bi-vis à pas direct tels que 9 avec un pas décroissant d'amont vers l'aval, et un module de bi-vis à pas inversé 10 pour réaliser une compression axiale des matières,
• des moyens de soutirage de la phase liquide situés au niveau de la zone Z₃ et combinant un filtre 11 et une sortie de liquide 12 (mis en service dans le cas où un déshuilage complémentaire des tourteaux est recherché),
• et une zone terminale de recueil des matières solides Z₄, comprenant un module de bi-vis à pas direct 13 et une sortie 14 des matières (tourteaux prêts au formage).

The system essentially includes the following functional areas (from upstream to downstream):

• a conveying and pressurizing zone Z ₁ , comprising a hopper 4 for supplying cake, decreasing twin-screw modules with direct pitch such as 5, and a conduit 6 provided with a pump 7 for the injection of 'water,
• a shear zone Z ₂ comprising one or more two-lobe disc mixers such as 8,
• a crushing and pressurizing zone Z ₃ , combining crushing modules constituted by twin-screw modules with direct pitch such as 9 with a decreasing pitch from upstream to downstream, and a bi-module inverted pitch screw 10 to achieve axial compression of the materials,
• means for withdrawing the liquid phase situated at the level of zone Z ₃ and combining a filter 11 and a liquid outlet 12 (put into service in the case where additional oil removal from the oil cakes is sought),
• and a terminal zone for collecting the solid materials Z ₄ , comprising a twin-screw module with direct pitch 13 and an outlet 14 for the materials (oil cakes ready for forming).

The conventional type mold shown diagrammatically in FIG. 3 is intended to carry out a cold forming as described in Example 1. This mold comprises, on the one hand, a hollow form 17, in the frustoconical example, fixed on a press plate 18 and having a removable bottom 19 to facilitate the demoulding, on the other hand, a conjugate counterform 20 fixed on the other plate 21 of the press. Correct positioning of the form and counter-form is ensured by a centering pin 22. Molding and demolding are carried out cold.

The conventional type mold shown diagrammatically in FIG. 4 is intended to carry out a thermoforming as described in Example 2, in order to obtain a hollow object of the same shape as in Example 1. This mold is similar to that of Figure 3, except that the inner wall of the hollow form is equipped with a grid 23 for evacuating steam and the bottom of a frit 24 connected to a duct 25 steam outlet. These forms and counter-forms are arranged in a heating press (not shown). During the thermoforming, a weak play about 1 mm is preserved above the hollow form to allow steam evacuation.

The conventional type mold shown diagrammatically in FIG. 5 is intended to carry out thermoforming of a panel as described in Example 3. This mold comprises, first of all, a form 26 combined with that of the panels desired, the bottom of which consists of a removable base 27 fitted with a sinter 28 connected to a water vapor discharge duct 29. The mold comprises also a counter-form 30 for closing off the form 26, this counter-form being equipped with a frit 31 connected to a steam evacuation duct 32. These shapes and counterforms are placed in a heating press.

EXAMPLE 1 : Composition of the raw material used

In this example, sunflower meal spent in oil, from the crushing of sunflower seeds, is used; the oil extraction was carried out by pressing and an extraction with hexane. After extraction, the composition of the meal is as follows: % Hydration rate % Minerals % Proteins % Fat % Cellulose % Lignin % Hemicellulose % Phenolic compounds 10.0 7.0 35.6 1.0 22.3 5.2 18.5 5.7

The median diameter D50 of the particles of the raw material is equal to 0.65 mm (dry measurement).

Mechanical preparation and hydration of the material in sight of obtaining a plastic paste.

Hydration, homogenization and division of matter are produced using the twin-screw device of FIGS. 1 and 2 already described. (The oil cake being completely de-oiled, the liquid outlet is not used).

The screw rotation speed is equal to 100 revolutions per minute and the device temperature is regulated and maintained at 30 ° C. The flow of cake injected at the head is close to 32 kg / h. About 32 l / h of water are inj ected.

The hydrated matter produced has a final weight rate hydration of 47% and a median diameter D50 of 0.4 mm (dry measurement). She is in the form of a homogeneous plastic paste and easily moldable.

Dough forming :

100 g of dough are placed in the mold of Figure 3. A pressure of 4 megapascals is exerted between form and counter-form. The demoulding is carried out cold. After demolding, the part retains its shape.

Drying of the molded part :

In this example, the part was dried in an oven ventilated at 60 ° C overnight. The part hardens and a shrinkage of approximately 1% can be seen. The hollow part obtained can be filled with soil or gravel without deformation.

Grinding and rehydration of the part allows reform a clean plastic paste to undergo a new forming.

EXAMPLE 2 : Composition of the raw material used

In this example, we use oil-exhausted cake from the crushing of sunflower seeds, the composition and granulometry in the raw state are identical to the cake used in Example 1.

Mechanical preparation and hydration :

The cake is first homogenized by grinding (grinder hammer fitted with a 0.5 mm grid). The D50 is reduced to 0.35 mm.

The cake is then mixed with water in proportions allowing a weight hydration rate equal to 38% to be obtained. The mixing is carried out in a "Perrier" kneader for 10 min, at temperature room.

Thermoforming :

100 g of material are placed in the mold of FIG. 4. The press is heated to 160 ° C. A pressure of 5 megapascals is exerted to adjust form and counter-form.

The mold is maintained at 160 ° C for about 1 min after the release of water vapor. The part is then removed from the mold. She is dry and rigid. No measurable shrinkage is observed. The room does not require further conditioning. Crushed and buried, the part degrades then disappears in a few weeks.

EXAMPLE 3 : Composition of the raw material

In this example, we use oil-exhausted cake from the crushing of sunflower seeds, the composition and granulometry in the raw state are identical to the cake of the previous examples.

Mechanical preparation :

The raw material is homogenized by grinding (hammer mill fitted with a 0.5mm grid). The D50 is reduced to 0.35mm.

The initial hydration rate of the meal is retained (10%).

Thermoforming :

30g of material are placed in the mold of Figure 5. The sintered were previously coated with a release agent. The temperature of the press lower plate is fixed at 150 ° C, that of the upper plate at 180 ° C. A pressure of 20.4 megapascals is applied and maintained for one minute after rebalancing the temperature of the press platens.

The part can then be removed from the mold. It is dry, flat and rigid. Once cooled, it does not require any special conditioning. Its mechanical characteristics are presented in the table below. They were measured on an XTRAD texturometer according to standard NF EN 310. E (mm) Rf (Mpa) Em (Mpa) Density (g / cm ³ ) 3.67 18.2 2545 1.00 E: thickness of test piece
Rf: resistance to breaking in bending
Em: modulus of elasticity

Placed in a saturated humidity environment, the room is covered with mold and begins to degrade after a few weeks.

Claims (12)

1. Method for production of an object which is biodegradable and can be composted and recycled, characterised in that it consists of (a) using a sunflower or rapeseed cake with an oil content by weight of less than 20% and a protein content by weight greater than 15% relative to the weight of dry material, which cake is hydrated such as to have a hydration level by weight of between 5% and 55% relative to the total material, (b) carrying out forming by pressing of the said cake in a mould with a shape suitable for that of the desired object, and (c) performing heat treatment or drying treatment in order to assure stiffening of the moulded object.
2. Production method according to claim 1, wherein a cake with a hydration level of between 10% and 25% relative to the total material is used, and in that thermal compression moulding of the said cake is carried out by bringing it up to a temperature of between 130°C and 200°C during pressing.
3. Production method according to claim 2, wherein the thermal compression moulding is performed at a pressure of between substantially 15 and 25 megapascals.
4. Production method according to one of claims 1, 2 or 3, wherein the sunflower or rapeseed cake is previously subjected to mechanical treatment of division and homogenisation, in order to provide it with granulometric distribution such that the equivalent median diameter of the particles D50 is between 0.1 mm and 1 mm.
5. Production method according to any one of claims 1 to 4, wherein a sunflower or rapeseed cake is used, from which the oil has been at least partially removed, with an oil content by weight of less than 10%.
6. Production method according to claim 5, wherein a sunflower cake from which all the oil has been extracted is used, and which is obtained by grinding of sunflower seeds or rapeseed.
7. Production method according to claim 5, wherein a cake is used which is divided and homogenised, and optionally has the oil removed from it by being passed into a double-screw screw device comprising, from upstream in the downstream direction, means for shearing (8), means for crushing (9), optionally means for drawing off a liquid phase (11, 12), at least one inverted-pitch module (10) in order to carry out axial compression of the solid materials, and an outlet (14) for the said solid materials, the said double-screw device being equipped with means for injection of water (6,7) in order to adjust the level of hydration of the cake obtained.
8. Method for production according to one of claims 1 to 7, wherein a sunflower or rapeseed cake enriched with vegetable fibres is used.
9. Method according to claim 1 for production of an object in cold conditions, wherein the sunflower or rapeseed cake is subjected to mechanical processing of division and homogenisation in order to provide it with granulometric distribution such that the equivalent median diameter of the particles, D50, is less than 1 mm, the said cake is hydrated to a hydration level of between 25% and 50% in order to obtain a resilient paste, the said paste is cold formed, and it is dried until it hardens.
10. Method according to claim 9, wherein the forming is performed at a pressure of between 1 and 5 megapascals.
11. Method according to any one of claims 1 to 10 for production of flat objects such as panels or slabs.
12. Method according to any one of claims 1 to 10 for production of hollow objects such as containers or packaging.

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