FR2784046A1 - PROCESS FOR MOLDING AN OBJECT BY INJECTION FROM PLANT RAW MATERIAL - Google Patents

Abstract

The injection molding process, using a material which is primarily of vegetable origin, initially heats it to a viscous liquid state or a pulp, to be injected under pressure into the mold. The primary material is an oilcake of sunflower or rape seed which has oil extracted so that the oil content is ≤ 25 wt.%. The moisture content is set at 2-40%. The granules have an average dia. of 0.1-1.2 mm, and the protein content of the fibers is evenly distributed. The oilcake has a max. 2 wt.% of oil, as a result of the attrition of the sunflower or rape seeds. The material has a hydration of 2-15%, to be heated to a temp. of 110-200 degrees C, to be pressed into a cold mold or at a mold temp. of ≤ 65 degrees C. Where the material has a hydration of 20-40%, it is heated to a temp. of 30-100 degrees C and pressed into a hot mold with a temp. of 90-140 degrees C. The sunflower or rape seeds are used without husks. The oilcake is enriched with vegetable proteins. The granules have an average dia. of 0.2-0.7 mm with a cut dia. of 0.8 mm. The material is homogenized and oil extracted partially in a twin-screw extruder. The extruder, from upstream to downstream, has an injector (6,7) for water and/or an alcohol solvent, a crushing zone (Z2) with at least one kneading crusher (8), a zone of crushing pressure (Z3), a bleed (11,12) for the liquid phase, at least one reverse pitch module (10) to apply an axial compression to the solid material, and an extrusion opening (14) for the solid matter.

Description

-I_ i 2784046

  METHOD OF MOLDING AN OBJECT BY INJECTION FROM

OF PLANT RAW MATERIAL

  The invention relates to a method of molding an object by injection of the type in which a raw material is brought by heating to the state of a viscous or pasty liquid, this is injected under pressure into a mold and a release is carried out. hardened material. The invention aims to take advantage of the performance of these injection processes (high rates, no handling, various forms obtained) to manufacture objects 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 capable of being degraded at least in its major part by natural microorganisms when it is put under the appropriate conditions, and this, without release of products toxic to the ecosystem , and on a 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 seek 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 by injection objects of composite material by using vegetable fibers such as wood, flax and hemp fibers, and by incorporating these fibers in a thermoplastic synthetic matrix to obtain

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  objects of good cohesion (GB-2 265 150). This solution does not entirely solve the problem of destruction of objects after use, due

  the presence of the plastic matrix.

  In addition, some publications have proposed injecting purified extracts of plant material, in particular soy protein extracts (US-5,523,293, "Schilling, Mechanical properties of biodegradable soy-protein plastics, J. Mater Res. Vol. 10, n 9, Sept. 1995, p.2197-2202 "). The essential shortcoming of this type of technique lies in its high cost, which comes essentially from the cost of obtaining purified extracts (cost of extracting o0 proteins for the examples of previous documents cited above). To the knowledge of the inventors, such techniques have never been used industrially because the proteins extracted have much more interesting outlets in other applications (in particular food) which allow better recovery than the manufacture of packaging or

packaging.

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

  remarkable savings conditions.

  Another objective of the invention is to manufacture an object which has good mechanical strength, compatible with common uses (small packages or packaging such as cups, pots, small

  containers, small objects of everyday life ...).

  To this end, the injection molding process targeted by the invention consists in heating a raw material to bring it to the state of a viscous or pasty liquid, in injecting it under pressure into a mold and in removing the mold from hardened material. According to the present invention, a raw material of sunflower or rapeseed meal having the following characteristics is used as the raw material for the injection: the said meal is at least partially deoiled so that its oil content by weight is less than 25%,

3,2784046

  - said cake is hydrated so as to have a hydration rate substantially between 2% and 40%, - said cake has a particle size distribution such that the median diameter Ds50 of its particles is between 0.1 mm and 1.2 mm, - the particles of the protein and fibrous constituents

  of said cake are dispersed in a substantially homogeneous manner.

  "Sunflower or rapeseed meal" means the solid residue from the extraction of oil from whole or shelled sunflower or rapeseed seeds, whatever the means of extraction (pressing, solvent extraction, etc.). ), this oil extraction can be total or partial but lowering

  the oil content by weight of the product below the above-mentioned threshold of 25%.

  By "median diameter D50" is meant a diameter such that% of the particles by weight pass through a vibrating screen having a mesh of side equal to said diameter. (All particle size measurements are made on dry matter). (All weight contents are expressed as a percentage relative to the weight of dry matter; the hydration rate is expressed relative to

total matter).

  Experiments have shown that from a raw material consisting of sunflower meal or rapeseed meal prepared appropriately to meet the conditions defined above, it was possible to achieve, by a conventional injection process , products of various forms, benefiting from excellent cohesion and quality of resistance of the order of that of common objects such as small containers, pots, cups, packaging, packaging ..., without the need for '' add any adjuvant. Thus, the process of the invention makes it possible to benefit from the high rates of injection processes and their flexibility of implementation in order to obtain very inexpensive objects from a natural raw material, abundant, without the addition of extracts, finished or semi-finished products, 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 food

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  animal to provide a low energy value), allows to implement under satisfactory conditions an injection process to manufacture an object of equivalent quality to that of objects injected in synthetic plastic. This remarkable result is explained a posteriori by the inventors by the composition of the sunflower or rapeseed meal, which contain proteins which lend themselves satisfactorily to injection and fibers which prove capable of forming a homogeneous whole with the protein matrix (without interfacial discontinuity despite the difference in chemical nature of these constituents). The water of hydration of the cake seems necessary to favor the transition to the viscous or pasty state of the raw material under thermal action. Furthermore, it has been found that the residual oil from the cake has a rather unfavorable effect. on the qualities of the objects obtained, in particular on their mechanical properties, and use is advantageously made of a sunflower or rapeseed meal exhausted in oil, that is to say containing at most 15% oil, derived in particular from trituration and solvent extraction of sunflower seeds or rapeseed seeds. This limits or suppresses the hydrophobic repulsive forces which tend to oppose the fiber / protein association. According to a first mode of implementation, called hot mold injection, a cake is used having a hydration rate substantially between 20% and 40%, and before injection, said cake is heated to a temperature between 30 C and 100 C, then is sent to a mold heated to a temperature between 90 C and 140 C. This mode of injection is relatively slow to implement and its optimization requires a high rate of hydration, to achieve at low temperature to obtain a viscous or pasty state of the cake allowing its injection into the mold under good conditions. According to another mode of implementation, known as cold mold injection, an oil cake having a hydration rate substantially between 2% and 15% is used, and, before injection, said oil cake is heated to a temperature between 1 10 C and 200 C, then sent under pressure in a cold mold or with a temperature below 65 C. This mode of injection

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  is commonly used for synthetic plastics and allows very high rates. Tests have shown that, in this cold mold injection, a cake hydration rate appreciably between 5% and 15% gives good results, in particular avoiding the formation of vapor pockets and reducing shrinkage of material. cooling, which leads to

more precise shapes.

  If one seeks to increase the mechanical performance of the objects obtained, it is possible to use a meal of shelled sunflower or rapeseed seeds, which naturally contains a higher proportion of o0 proteins. Of course, it is also possible, in certain applications, to use a sunflower or rapeseed meal enriched with vegetable proteins by addition in order to further increase these mechanical performances at the cost of a

cost increase.

  In the process of the invention, the sunflower or rapeseed meal is subjected beforehand to a mechanical treatment of division and homogenization to give it the particle size distribution previously defined; preferably, this treatment is carried out so that the median diameter D50 of the particles is substantially between 0.2 mm and 0.7 mm, and the cut-off diameter D95 is less than or equal to 0.8 mm. By "cut-off diameter D95" is meant a diameter such that 5% of the particles by weight are

  stopped by a vibrating sieve having a mesh side equal to said diameter.

  Such a distribution can in particular be obtained by passing the cake through a twin-screw device which ensures a division, a homogenization and if necessary a partial or complete deoiling thereof, capable of leading to a better quality of the objects injected (better

  mechanical resistance, less defects and shrinkage of material). The bi-

  screw can optionally be chosen to ensure complete oil removal from oil cakes (without any other oil extraction operation) or, on the contrary, be coupled downstream of a conventional extraction press ensuring oil removal or part of

this one.

  The method of the invention makes it possible to manufacture biodegradable, compostable and recyclable shaped objects, essentially consisting

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  of a protein matrix reinforced by vegetable fibers oriented in one or more preferred directions and having a resistance to bending substantially

  between 3 and 30 megapascals.

  The examples which follow are intended to illustrate the process of the invention. In Examples 1 and 3, the cake after oil removal by twin-screw or traditional pressing is subjected to a preliminary preparation treatment in a twin-screw device of specific configuration; this twin-screw device and the injection device enabling the injection to then be carried out are shown diagrammatically in the attached drawings; in these drawings: FIG. 1 is a symbolic longitudinal representation of said twin-screw device, FIG. 2 is a cross section through a plane A, FIG. 3 is a symbolic diagram of the press

  inject used in the examples.

  The twin-screw device shown diagrammatically in FIGS. 1 and 2 is used to carry out the prior preparation of the cake after oil removal; this device is obtained from modules sold by the company "CLEXTRAL" (registered trademark) under the general reference "BC45". Each module includes a double wall tubular enclosure 1 and 2 which allows a

  thermal regulation of the heart of the enclosure where the active organs are housed.

  Some modules are of the type comprising two identical co-penetrating screws, others of the type comprising shear mixers composed of bilobe discs or kneader 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 700 rpm. In the examples,

  the rotational speed chosen varies from 100 rpm to 200 rpm.

  The device essentially comprises the following functional zones (from upstream to downstream): - a zone for conveying and pressurizing ZI, comprising a hopper 4 for supplying oil cakes, twin-screw modules with decreasing direct pitch such as 5 , and a conduit 6 provided with a pump 7 for injection

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  of water and / or an alcoholic solvent, - a shear zone Z2, comprising one or more mixers with bi-lobed discs such as 8, - a crushing and pressurizing zone Z3, combining crushing modules constituted by twin-screw modules with direct pitch such as 9, with a decreasing pitch from upstream to downstream, one or more twin-screw modules with inverted pitch 10 to achieve axial compression of the materials, - means for withdrawal of 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 from the oil cakes is sought), - and a terminal area for collecting solid materials Z4, including direct screw twin screw modules 13 and material outlet 14

(oil cakes ready for injection).

  The injection molding machine symbolized in FIG. 3 is a 90 t press, comprising a cake feed hopper 15, a conveyor and pressurizing auger 16, a pressure injection nose 17 and a

  mold 18 of known type, with opening by jacks.

Example 1:

  Composition of the raw material used In this example, two-screw sunflower meal is used, the composition of which is as follows

%%%%%%%%%

  mineral levels protein / lipids / cellulose / lignin / hemicel- hydra compounds / MS MS MS MS MS lulose / MS phenolics / MS ration

10.8 5.2 26.7 25 16.7 3.9 14.9 4. 3

  Preparation of the material: The hydration and the homogenization of the material are

  made using the twin-screw device described (Figures 1 and 2).

  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 100 C. The flow rate

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  of raw material injected at the head is close to 24 kg / h.

  About 9 I / h of water are injected through line 6 at the level

of the ZI zone.

  The hydrated material produced has a final moisture content of 24%, an equivalent median diameter D50 of 0.35 mm (dry measurement) and a cut-off diameter D95 of 0.8 mm. It comes in the form of a paste

homogeneous friable.

  Injection: The injection is carried out using the injection press described

o0 figure 3.

  The injection and molding parameters are as follows: the maximum temperature in the screw 16 (Tv), the mold temperature (Tm), the injection limit pressure (Pli), 15. the holding pressures (Pml, Pm2) , the duration of the holding pressures (tl, t2),

the solidification time (ts).

  For the example treated, the value of these parameters is given in the following table: Tm (C) Tv (C) Pli (b) Pml (b) Pm2 (b) tl (s) t2 (s) ts (s)

103 50 40 30 30 25 50 90

  The pieces formed are standard test pieces of the dumbbell type lA (ISO 527) used for the measurement of tensile strength, rectangular pieces 60 × 10 × 4 mm used for the resistance measurements in

  bending and 90mm diameter discs.

  The maturation is carried out at 50 C for 12 hours.

  The shrinkage observed during maturation is 1.4% over

  the large dimension of the rectangular part.

  The mechanical characteristics of the parts, measured on a TAXT2 Texturometer (Rhéo) after conditioning at 25 C and 60% humidity for 24 h are presented in the following table

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  Flexion (Mpa) Traction (Mpa) Young Module Resistance Young Module Resistance

  3.5 + 0.5 497 + 40 1.2 + 0.17 110 + 3

Example 2:

  Composition of the raw material In this example, bi-screw expression cake is used, the composition of which is as follows:

%%%%%%%%%

  mineral levels protein / lipids / cellulose / lignin / hemicel- hydra compounds / MS MS MS MS MS lulose / MS phenolics / MS ration

10.8 5.2 26.7 25 16.7 3.9 14.9 4. 3

  Preparation of the material In this example, the material does not undergo additional hydration or homogenization. It has a humidity rate of 9%, a Ds50 of

  1o 0.35 mm and a D95 of 0.8 mm. It comes in a powder form.

  Injection Shaping is carried out using the injection press

described (Figure 3).

  For the example treated, the value of the injection parameters is given in the following table: Tm (C) Tv (C) Pli (b) Pml (b) Pm2 (b) t (s), t2 (s), ts (s)

190 30 30 20 35

  The parts formed are the same as those described in example 1. The maturation is done in the same way as in example 1. The shrinkage during maturation is very low and cannot be evaluated in a reliable manner. 2784046 . The bending resistance of the parts, measured on a TAXT2 texturometer (Rhéo) after conditioning at 25 C and 60% humidity is presented in the following table Resistance (MPa) Young's modulus (MPa)

5.12 1147

Example 3

  Composition of the raw material In this example, oil-exhausted oil cake from the crushing of sunflower seeds is used, the composition of which is as follows%%%%%% d%% mineral protein / lipid / cellulose / lignin / hemicel- hydra compounds / MS MS MS MS MS lulose / MS phenolic / MS tation

10.0 7.0 35.6 1.0 22.3 5.2 18.5 5.7

  The D50 of the material is equal to 0.65 and its D95 to 2.

  Mechanical preparation and hydration of matter Hydration, homogenization and division of matter

  are made using a twin-screw device with the profile illustrated in Figures 1 and 2.

  The screw rotation speed is equal to 200 revolutions per minute and the temperature of the device is regulated and maintained at 100 C. The flow rate

  of raw material injected at the head is close to 23 kg / h.

  About 3 1 / h of water is injected into line 6 at the level

of zone Z1.

  The hydrated material produced has a final moisture content of% and, when dry, a D50 of 0.4 mm and a D95 of 0.7mm. It is presented under the

form of a crumbly paste.

  Injection: The shaping is carried out using the injection press

described.

  -it 2784046 For the example treated, the value of the injection molding parameters is given in the following table: Tm (C) Tv (C) Fold (b) Pml (b) t l (s) ts (s)

115 110 100 5 13

  The parts formed are similar to those described in Example 1. The maturation is done in the same way as in

Example 1.

  The shrinkage observed during maturation is 1.7% over

  the length of the rectangular part and 3% across its width.

  The mechanical flexural characteristics measured on TAXT2 Texturometer (Rhéo) after conditioning at 25 C and 60% humidity for 24 h are presented in the following table: Resistance (MPa) Young's modulus (MPa)

14.1 2156

Example 4:

  Composition of the raw material: In this example, oil-exhausted oil cake from the crushing of sunflower seeds is used, the composition of which is as follows:

%%% /%% /%%%

  mineral levels protein / lipids / cellulose / lignin / hemicel- hydra compounds / MS MS MS MS MS lulose / MS phenolics / MS ration

  10.0 7.0 35.6 1.0 22.3 5.2 18.5 5. 7

  The D50 of the material is equal to 0.65 and its D95 to 2.

  Mechanical preparation of matter Hydration, homogenization and division of matter

  are made using a twin-screw device with the profile illustrated in Figures 1 and 2.

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  The screw rotation speed is equal to 200 revolutions per minute and the temperature of the device is regulated and maintained at 100 C. The flow rate

  of raw material injected at the head is close to 25 kg / h.

  About 0.5 l / h of water is injected into line 6 at the level of zone Z1. The material produced has a final moisture content of 2% and, when dry, a D50 of 0.4 mm and a D95 of 0.7mm. It comes in the form of a

crumbly dough.

  Injection The shaping is carried out using the injection molding machine described. For the example treated, the value of the injection molding parameters is given in the following table: Tm (C) Tv (C) Fold (b) Pml (b) tl (s) ts (s)

56 115 110 40 5 13

  The formed parts are similar to those described in

Example 1.

  Maturation is done in the same way as in

Example 1.

  The shrinkage observed during maturation is 2.9% over

  the length of the rectangular part and 3.8% across its width.

  The mechanical flexural characteristics measured on TAXT2 Texturometer (Rhéo) after conditioning at 25 C and 60% humidity for 24 h are presented in the following table: Resistance (MPa) Young's modulus (MPa)

21.3 2531

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Claims (6)

  1 / - Process for molding an object by injection, in which a raw material is brought by heating to the state of viscous or pasty liquid, this is injected under pressure into a mold and the material is removed from the mold hardened, characterized in that a raw material of sunflower or rapeseed meal having the following characteristics is used: - said meal is at least partially oiled so that its oil content by weight is less than 25%, - said meal is hydrated so as to have a hydration rate substantially between 2% and 40%, - said cake has a particle size distribution such that the median diameter D50 of its particles is between 0.1 mm and 1.2 mm, - particles of protein and fibrous constituents   of said cake are dispersed in a substantially homogeneous manner.   2 / - Injection method according to claim 1, characterized in that one uses a sunflower meal or rapeseed oil exhausted, containing at most 2% oil, in particular from the crushing of sunflower seeds or rapeseed.   3 / - Injection method according to one of claims 1 or   2, characterized in that one uses a cake having a hydration rate substantially between 2% and 15%, said cake being heated to a temperature between 110 C and 200 C and sent under pressure in a cold mold or having a temperature below 65 C.   4 / - Injection method according to one of claims 1 or   2, characterized in that one uses a cake having a hydration rate substantially between 20% and 40%, said cake being heated to a temperature between 30 C and 100 C and sent under pressure in a mold heated to a temperature between 90 C and 140 C. 14 2784046   / - Injection method according to one of claims 1, 2,   3 or 4, characterized in that a meal of shelled sunflower or rapeseed seeds is used.   6 / - Injection method according to one of claims 1, 2,   3 or 4, characterized in that a sunflower or rapeseed meal enriched with vegetable proteins.   7 / - Method according to one of the preceding claims,   characterized in that one uses a cake having a particle size distribution such that the median diameter D50 of its particles is between 0.2 mm and 0.7 mm, and the cut-off diameter D95 is less than or equal to 0.8 mm . 8 / - Method according to claim 7, characterized in that one uses a divided cake, homogenized and at least partially deoiled   by passing sunflower or rapeseed seeds through a twin-screw device.   1 5 9 / - Method according to claim 8, in which a twin-screw device is used comprising, from upstream to downstream, where appropriate means (6, 7) for injecting water and / or a alcoholic solvent, a shear zone (Z2) comprising at least one shear mixer (8), a crushing and pressurization zone (Z3), means (11, 12) for withdrawing the liquid phase, at least an inverted step module (10) for achieving axial compression of the   solids, and a solids outlet (14).   / - Molded biodegradable, compostable and recyclable object, capable of being manufactured by implementing an injection process   according to one of claims 1 to 9, characterized in that it is   essentially consisting of a protein matrix reinforced by plant fibers oriented in one or more preferred directions and in that it has   a flexural strength substantially between 3 and 30 megapascals.