FR2784047A1 - METHOD FOR MANUFACTURING OBJECTS FROM VEGETABLE RAW MATERIAL BY FORMING OR THERMOFORMING - 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

PROCESS FOR MANUFACTURING OBJECTS FROM MATERIAL

  FIRST PLANT BY FORMING OR THERMOFORMING

  The invention relates to a method of manufacturing objects from vegetable raw material. It aims to make it possible to manufacture objects such as containers, packaging, panels or plates, in particular for construction or furniture, which, while benefiting from durability and stability characteristics compatible with their function, are biodegradable, compostable and recyclable . By "biodegradable" is meant that said object is

  likely to be degraded at least in large part by micro-

  natural organisms when put under the appropriate conditions, and this without release of toxic products for the ecosystem, and on the scale of a few weeks to a few months. By "compostable" is meant an object which, divided, homogenized and mixed with organic matter and / or soil, provides a non-toxic nutritious 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 becoming more and more 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 character in order to avoid that 'they

  become pollution or require expensive disposal treatments.

  Synthetic plastics generally meet the latter requirement, but recycling is expensive and requires prior sorting to separate the various types of materials, which are not very compatible with the

current lifestyle.

  To limit these drawbacks, numerous studies have proposed making objects using various plant materials such as wood fiber, sunflower shell, and combining these materials with synthetic binders or glues to obtain objects of good cohesion (US- 5,593,625, US-S 663,221). This solution does not entirely solve the problem of the destruction of objects after use, due to the presence of synthetic materials. In addition, the most common synthetic binders and glues have the

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  failure to release toxic products, either gradually over time (urea-formaldehyde, phenol-formaldehyde), or during manufacture or recycling (isocyanates). Furthermore, some publications have proposed replacing synthetic binders with natural binders, in particular gelatin (WO-96/14361). This type of process consists in mixing a vegetable load (essentially fibrous) and the natural binder to constitute a paste, and in heating the latter in order to ensure the diffusion of the binder in the mass and the shaping of the product. The essential defect of this technique resides in its cost coming o0 essentially from the cost of raw materials, which constitute extracted, finished or semi-finished products. In addition, the mechanical performances of the materials produced so far by this type of technique are poor.

  (mechanical resistance comparable to that of cardboard).

  The present invention proposes to overcome the drawbacks of known methods and to indicate a new method for manufacturing a biodegradable, compostable and recyclable object in

  remarkable saving conditions.

  Another objective 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 an oil content by weight of less than 20% and a protein content by weight of more than 15%, hydrated so to present a weight rate of hydration appreciably between 5% and 55%, (b) to form by pressing said cake in a shape adapted to that of the desired object and (c) to carry out a heat treatment or a drying treatment to ensure

stiffening of the shaped object.

  By "sunflower or rapeseed meal" is meant in the usual way the solid residue from the extraction of whole or shelled sunflower or rapeseed oil, whatever the means of extraction (pressing, solvent extraction ...), this oil extraction can be total or partial

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  but lowering the oil content by weight of the product below a threshold generally of the order of 20%; the meal may or may not have been the subject of a preliminary partial protein extraction, its protein content by weight however remaining greater than 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 a raw material consisting of sunflower meal or rapeseed meal, prepared in an appropriate manner to satisfy the conditions previously defined, it was possible to produce, by a conventional process of forming or thermoforming, shaped products, benefiting from excellent cohesion and remarkable quality of resistance, without the need to add 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 as a by-product of little value (used only in animal feed to ensure a contribution of low energy value), allows implement under satisfactory conditions a forming or thermoforming process to manufacture an object of equivalent quality to that of thermoformed objects made of synthetic plastic. This remarkable result is explained a posteriori by the inventors by the composition of sunflower or rapeseed meal, which contain fibers and proteins, the latter having a nature and a content suitable for diffusing and associating the fibers until constituting with those -this a matrix suitable for forming. The water of hydration of the cake used has a solvating action on these proteins, the chains of which unfold to interact with the fibers. The process of the invention can be implemented by thermoforming the cake, which consists in bringing it, during pressing, to a temperature substantially between 130 ° C. and 200 ° C. In this case, the rate is adjusted beforehand hydration of the meal to a value included

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  between 5% and 25%. This range of values allows good heat transfers, satisfactory deployment of the protein chains, without excessive degassing liable to locally weaken the material. Preferably, the thermoforming is carried out at a pressure substantially between 15 and 25 megapascals. Such a 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, the sunflower or rapeseed meal is preferably subjected beforehand to a mechanical treatment of division and homogenization to give it a particle size distribution such that the median diameter of the particles D50 is substantially between 0.1 mm and 1 mm. By "median diameter D50" is meant a diameter such that 50% of the particles by weight pass through a vibrating screen having a mesh of 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 construction, essentially consisting of vegetable fibers bound by proteins, having a flexural strength substantially between 10

and 25 megapascals.

  According to another mode of implementation, the cake, previously subjected to a mechanical treatment of division and homogenization to give it a particle size distribution such that the median diameter of the particles D50 is less than 1 mm, is hydrated, by a 2s 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 those of a modeling dough) and allows objects of very varied shapes to be produced at very low prices. However, the mechanical resistance of the objects obtained is lower than in the case of implementation by thermoforming

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as previously mentioned.

  Furthermore, it has been found that the residual oil from the oil cake has an unfavorable effect on the forming and the qualities of the objects obtained, and an oil cake at least partially deoiled is advantageously used, having an oil content by weight of less than 10%. . It is possible, if necessary, to use a meal exhausted in oil, resulting from the crushing of sunflower seeds or rapeseed seeds. (Generally, "oil-exhausted oil cake" means oil cake containing at most 2% oil). This limits or suppresses the hydrophobic repulsive forces which tend to oppose

  o10 the fiber / protein association.

  The meal can in particular be divided and homogenized,

  and possibly at least partially de-oiled, by passing through a two-part device

  screw comprising, from upstream to downstream, shearing means, crushing means, means for drawing off the liquid phase, at least one inverted pitch module for achieving axial compression of the solid materials, and an outlet for the materials solids, said twin-screw device being further equipped with water injection means in order to adjust the hydration rate of the cake. Such a treatment refines the texture of the meal and allows the association of fibers and proteins to be generated in optimal conditions during the forrnage. In addition, it allows, if necessary, to provide additional oil removal from the cake. The sunflower or rapeseed meal can if necessary be enriched with vegetable fibers in order to further lower the cost price of the objects obtained. This mode of implementation which makes it possible to exploit existing stocks of vegetable fibers of low value (straw, sunflower shell) will be used in particular when using a cake containing all its original proteins (without partial extraction) or when the object sought is not subject

  to severe mechanical strength requirements.

  The process 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

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of the invention.

  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; in these drawings: FIG. 1 is a symbolic longitudinal representation of said bi-screw device, FIG. 2 is a cross section through a plane A, 10. 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 FIGS. 1 and 2 is used to carry out the prior preparation of the oil cakes in Example 1; this device is obtained from modules sold by the company "CLEXTRAL" (registered trademark) under the general reference "BC45". Each module includes a tubular double-walled enclosure 1 and 2 which allows thermal regulation of the core of the enclosure where the active members are housed. Some modules are of the type comprising two identical co-penetrating screws, others of the type comprising shear mixers composed of bi-lobed discs. The various modules are rotated in synchronism by an electric motor 3 making it possible to obtain a speed of rotation of its output shaft which can reach

  700rpm. In the examples, the speed of rotation chosen is 10Otr / min.

  The device essentially comprises the following functional zones (from upstream to downstream): - a zone for conveying and pressurizing Z., comprising a hopper 4 for feeding oil cakes, twin-screw modules with decreasing direct pitch such as 5, and a conduit 6 provided with a pump 7 for the injection of water, - a shear zone Z2, comprising one or more kneaders with bilobed discs such as 8, - a crushing and pressurizing zone Z3 , combining crushing modules made up of twin screw modules

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  direct such as 9 with a decreasing step from upstream to downstream, and a bi-

  inverted pitch screw 10 to achieve axial compression of the materials, means for drawing off the liquid phase located at the zone Z3 and combining a filter 11 and a liquid outlet 12 (put into service in the case where additional oil removal is carried out oil cake is sought), - and a terminal zone for collecting solid materials Z4, comprising a twin-screw module with direct pitch 13 and an outlet 14 for the materials

(oil cakes ready for forming).

  The mold of the conventional type shown diagrammatically in FIG. 3 is intended to carry out 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 demolding, 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 thermoforming as described in Example 2, with a view to obtaining a hollow object of the same shape as in Example 1. This mold is similar to that in FIG. 3, except that the internal wall of the hollow form is equipped with a grid 23 for discharging steam and the bottom of a frit 24 connected to a duct 25 for discharging steam. These forms and counter-forms are arranged in a heating press (not shown). During thermoforming, a small clearance of about 1 mm is preserved above the hollow form to allow

steam evacuation.

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

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  counterforms are placed in a heating press.

EXAMPLE 1:

  Composition of the raw material used In this example, sunflower meal exhausted in oil is used, resulting from the crushing of sunflower seeds; the oil extraction was carried out by pressing and an extraction with hexane. After extraction, the composition of the meal is as follows:

%%%%%%%%%

  Minerals Proteins Lipids Cellulose Lignin Hemi- Phenolic hydracellulose 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 the material are carried out 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 speed of rotation of the screws is equal to 100 revolutions per minute and the temperature of the device is regulated and maintained at 30 C. The flow rate of cake injected at the head is close to 32 kg / h. About 32 I / h of water are injected. The hydrated matter produced has a final weight rate of hydration of 47% and a median diameter D50 of 0.4 mm (dry measurement). It comes in the form of a homogeneous and easily moldable plastic paste. Forming of the dough: 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

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  an oven ventilated at 60 C overnight. The part hardens and a shrinkage of around 1% can be seen. The hollow part obtained can be filled with soil or

gravel without deformation.

  Grinding and rehydration of the part makes it possible to reform a plastic paste suitable for undergoing a new forming.

EXAMPLE 2:

  Composition of the raw material used In this example, oil-exhausted oil cake from the crushing of sunflower seeds is used, 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 room temperature. Thermoforming:

  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 approximately 1 min after the end of the evolution of water vapor. The part is then removed from the mold. It is dry and rigid. No measurable shrinkage is observed. The part 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, oil-exhausted oil cake from the crushing of sunflower seeds is used, the composition and

  granulometry in the raw state are identical to the cake of the previous examples.

Mechanical preparation

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  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: g of material are placed in the mold of FIG. 5. The frits were previously coated with a release agent. The temperature of the lower plate of the press is fixed at 150 C, that of the upper plate at 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 / cm3)

3.67 18.2 2545 1.00

  E: thickness of the test piece Rf: resistance to flexural rupture Em: modulus of elasticity Placed in a medium saturated with humidity, the part is covered with

  mold and begins to degrade after a few weeks.

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Claims (9)

  1 / - Process for manufacturing a biodegradable, compostable and recyclable object, characterized in that it consists (a) of using a sunflower or rapeseed meal having an oil content by weight of less than 20% and a weight content of proteins greater than 15%, hydrated so as to present a weighted rate of hydration appreciably between 5% and 55%, (b) forming by pressing said cake in a shape adapted to that of the desired object and ( c) to carry out a heat treatment or a treatment of   drying in order to stiffen the shaped object.   2 / - The manufacturing method according to claim 1, wherein one uses a cake having a hydration rate substantially between 10% and 25% and in that one operates a thermoforming of said cake by carrying it during pressing to a temperature substantially between 130 C and C. 3 / - Manufacturing process according to claim 2, wherein the thermoforming is carried out at a pressure substantially between and 25 megapascals.   4 / - Manufacturing method according to one of claims 1,   2 or 3, in which the sunflower or rapeseed meal is subjected beforehand to a mechanical treatment of division and homogenization to give it a particle size distribution such that the equivalent median diameter of the   D50 particles is substantially between 0.1 mm and 1 mm.   / - Manufacturing method according to one of claims   1 to 4, in which at least one sunflower or rapeseed meal is used   partially deoiled, having an oil content of less than 10% by weight.   6 / - The manufacturing method according to claim 5, wherein one uses a sunflower meal exhausted in oil, from the trituration of sunflower or rapeseed seeds.   7 / - The manufacturing method according to claim 5, wherein a cake is divided and homogenized and optionally deoiled by passage through a twin-screw device comprising, from upstream to downstream, shearing means (8), means d 'crushing (9), if necessary, of the means of 12 2784047   drawing off a liquid phase (11, 12), at least one module with inverted steps (10) for carrying out an axial compression of the solid materials, and an outlet (14) for the said solid materials, the said twin-screw device being equipped with means   water injection (6, 7) in order to adjust the hydration rate of the cake obtained.   8 / - Manufacturing process according to one of claims 1   to 7, in which a sunflower or rapeseed meal enriched with vegetable fibers is used. 9 / - Process according to claim 1 for the cold manufacture of an object, in which the sunflower or rapeseed meal is subjected to a mechanical division and homogenization treatment to give it a particle size distribution such that the equivalent median diameter particles D50 is less than 1 mm, said cake is hydrated at a hydration rate substantially between 25% and 50% in order to obtain a plastic paste, a cold forming of said paste is carried out, and drying is carried out of this until hardening.   / - Method according to claim 9, wherein the forming is carried out at a pressure substantially between 1 and 5 megapascals.   11 / - Method according to one of claims 1 to 10 for the   manufacture of flat objects such as panels or plates.   12 / - Method according to one of claims 1 to 10 for the   manufacture of hollow objects such as containers or packaging.   13 / - Thermoformed panel usable in particular in construction, manufactured by implementing the method according to claim 2, characterized in that it essentially consists of vegetable fibers bound by proteins and in that it has resistance at bending substantially   between 10 and 25 megapascals.