ES2242358T3 - MOLDING PROCEDURE OF AN OBJECT BY INJECTION FROM VEGETABLE 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

Molding procedure of an object by injection from plant raw material.

The present invention relates to a process of molding an object by injection of the type in the which is taken by heating a raw material to the state of viscous or pasty liquid, it is injected under pressure in a mold and demolding of hardened matter is carried out. The invention envisages taking advantage of some features of these procedures of injection (high rates, lack of support, forms varied obtained) to manufacture objects that, taking advantage of durability and stability features compatible with your function, be biodegradable, compostable and recyclable. By "biodegradable" means that said object is susceptible to be degraded at least for the most part by natural microorganisms when put in the conditions appropriate, and this, without release of toxic products for the ecosystem, and on the scale of a few weeks to a few months. By "compostable" means an object that, divided, homogenized and mixed with organic matter and / or a soil, It provides a non-toxic nutrient substrate for plants. By "recyclable" means an object whose material can be reused to form an object of the same range.

Environmental obligations are increasingly severe, in particular for disposable products (in particular packaging and conditioning), and seeks to manufacture these products giving them a biodegradable and / or compostable character and / or recyclable in order to prevent them from becoming a pollution or needing Onerous removal treatments. Plastic materials Synthetics generally satisfy the last requirement but their Recycling is a high cost and needs some previous selections to separate the various types of materials, selections that are little compatible with the current way of life.

To limit these inconveniences, numerous studies have proposed to manufacture by injection some objects of composite material using plant fibers such as fibers of wood, linen and hemp, and incorporating these fibers in a thermoplastic synthetic matrix to obtain good objects cohesion (GB-2 265 150). This solution does not solve completely the problem of destruction of objects after of use, due to the presence of the material matrix synthetic.

Some publications have proposed to inject some purified extracts of plant material, in particular extracts Soy Protein (US-5 523 293, "Schilling, Mechanical properties of biodegradable soy-protein plastics, J. Mater Res. Vol. 10, nº 9 Sept. 1995, p. 2197-2202 "). The essential defect of this type of techniques lies in its high cost that comes essentially from cost of obtaining purified extracts (extraction cost of proteins for the examples in the previous documents cited above). These techniques have never been, according to the knowledge of the inventors, used industrially due to that the proteins extracted some more interesting outputs in other applications (particularly food) that allow a better recovery than the manufacture of packaging or conditioning.

On the other hand, it should also be noted that some lignocellulosic residues from procedures oil extraction have been heat pressed to give them a cohesion and a certain resistance.

The present invention aims to avoid drawbacks of known procedures and indicate a new procedure that allows an object to be manufactured by injection biodegradable, compostable and recyclable in remarkable conditions of Economy.

Another object of the invention is to manufacture a object that benefits from good mechanical strength, compatible with current uses (small conditioning or packaging such as glasses, boats, small containers, small objects of ordinary life ...).

To this end, the molding process by injection provided by the invention consists in heating a matter premium to take it to the viscous or pasty liquid state, in to inject it under pressure in a mold and to unmold the hardened matter. According to the present invention, it is used as raw material to make the injection a sunflower cake or Rapeseed that has the following characteristics:

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bliss cake is at least partially uncoupled so that your weight content of oil is less than 25%,

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bliss cake is hydrated so that it presents a percentage of hydration significantly between 2% and 40%,

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Bliss cake has a particle size distribution such that the diameter D50 medium of its particles is between 0.1 mm and 1.2 mm

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the particles of the protein and fibrous constituents of said cake they are dispersed in a substantially homogeneous way.

By "sunflower or rapeseed cake", it understands the solid residue of grain oil extraction from sunflower or rapeseed whole or bark, whatever the Extraction medium (pressing, solvent extraction ...), this oil extraction can be total or partial but lowering the weight content of the product's oil below of the above threshold of 25%.

By "average diameter D 50", it is understood a diameter such that 50% of the particles by weight pass through a vibrating sieve that has a side mesh equal to the diameter. (All granulometric measurements are made on the subject dry). (All the weighted contents are expressed in percentage with respect to the weight of dry matter; the percentage of hydration is expressed with respect to the total matter).

Experiments have allowed us to verify that from a raw material consisting of sunflower cake or cake of properly prepared rapeseed to meet the conditions previously defined, it was possible to perform, by a classic injection process, a variety of products, which they benefit from excellent cohesion and resistance quality of the order of that of ordinary objects such as small containers, boats, glasses, packaging, packaging ..., and this, without the need to add any adjuvant. Thus, the procedure of the invention allows to take advantage of the cadences high levels of injection procedures and their flexibility of use to obtain very economical objects from a natural raw material, abundant, without the addition of extracts, finished or semi-finished products, synthetic or natural products. It is totally unexpected that said sunflower or vegetable waste Rapeseed, very heterogeneous and currently considered as a byproduct of little value (used only in animal feed for ensure a contribution of low energy value), allow to make under satisfactory conditions an injection procedure to manufacture an object of equivalent quality to that of the objects injected in synthetic plastic material. This remarkable result it is explained a posteriori by the inventors by the composition of sunflower or rapeseed cakes, which contain some proteins that lend successfully to the injection and fibers that are suitable to form a homogeneous assembly with the protein matrix (without interfacial discontinuity despite the difference of chemical nature of these constituents). Water Hydration of the cake seemed necessary to favor the passage to the viscous or pasty state of the raw material under the action thermal

On the other hand, it has been found that the residual cake oil has a rather unfavorable effect on the qualities of the objects obtained, in particular on its mechanical properties, and a cake of advantageously is used sunflower or rapeseed oil depleted, that is, it contains as maximum 2% oil, in particular from crushing and solvent extraction of sunflower seeds or rapeseed grains. The hydrophobic repulsive forces that are limited or suppressed are thus suppressed. They tend to oppose the fiber / protein association.

According to a first embodiment, called hot mold injection, a cake representing a percentage of hydration substantially between 20% and 40%, and before injection, said cake is heated to a temperature between 30ºC and 100ºC, and then it is sent to a mold heated to a temperature between 90 ° C and 140 ° C. This injection mode is relatively slow and its optimization requires a high percentage of hydration, to reach low temperature to obtain a viscous or pasty state of the cake that allows its injection into the mold in good terms.

According to another embodiment, called cold mold injection, a cake is used that has a percentage of hydration substantially between 2% and 15%, and, before injection, said cake is heated to a temperature between 110ºC and 200ºC, and then sent under pressure to a cold mold or that has a temperature below 65ºC. This way Injection is currently used for materials synthetic plastics and allows very high rates. The trials have shown that, in this cold mold injection, a cake hydration percentage significantly understood between 5% and 15% give good results, avoiding in particular the formation of steam bags and reducing contractions of material when cooled, which leads to more precise shapes.

If it is sought to increase the mechanical characteristics of the objects obtained, it is possible to use a cake of barked sunflower or rapeseed grains, which naturally contains a higher proportion of proteins. Of course, it is also possible, in certain applications, to use a sunflower or rapeseed cake enriched with vegetable proteins by addition in order to still increase these mechanical characteristics at the price of an increase in
cost.

In the process of the invention, the cake of Sunflower or rapeseed is previously subjected to mechanical treatment of division and homogenization to confer the distribution granulometric previously defined; preferably this treatment is carried out so that the average diameter D 50 of the particles are substantially between 0.2 mm and 0.7 mm, and the cutting diameter D 95 is less than or equal to 0.8 mm. By "cutting diameter D 95", such a diameter is understood that 5% of the particles by weight are stopped by a vibrating screen which has a side mesh equal to said diameter.

Said distribution may in particular be obtained by passing the cake through a bitornillo device that ensures a division, a homogenization and if necessary a partial or complete unwanted of this, appropriate to lead to better quality of injected objects (better assistance mechanical, less defects and material contraction). The device bitornillo can eventually be chosen to ensure the complete unwanted cakes (without other extraction operation oil) or, conversely, be coupled downstream of a classic extraction press that ensures the unwanted or a part of this.

The process of the invention allows manufacturing biodegradable, compostable and recyclable molded objects, essentially constituted by a protein matrix reinforced by plant fibers oriented in one or some directions privileged and have a flexural strength substantially between 3 and 30 megapascals.

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

In examples 1 and 3, the cake, after unleashed by bitornillo or traditional pressing, is subjected to a pre-preparation treatment in a bitornillo device specific configuration; this bitornillo device and the injection device that allows you to perform the Injection are schematized in the attached drawings; in these blueprints:

\ cdot Figure 1 is a representation symbolic longitudinal of said bitornillo device,

Figure 2 is a cross section by a plane A,

Figure 3 is a symbolic scheme of the injection press used in the examples.

The schematic bitornillo device in the Figures 1 and 2 is used to carry out the previous preparation of the cakes after the unwanted; this device is obtained at from modules marketed by the Company "CLEXTRAL" (registered trademark) under the general reference "BC45". Every module comprises a double wall tubular enclosure 1 and 2 that allows a thermal regulation of the core of the enclosure where they are housed the active organs. Some modules are of the type that includes two identical copenetrating screws, others of the type comprising shear malaxers composed of bilobular discs or by malaxador discs. The various modules are dragged into rotation in synchronism by an electric motor 3 that allows to obtain a rotation speed of its output shaft that can reach 700 laps / min. In the examples, the chosen rotation speed varies from 100 laps / min to 200 laps / min.

The device essentially comprises the zones following functional (upstream downstream):

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a transport and pressure zone Z_ {1}, comprising a 4 cakes feed hopper, of the drainage modules with decreasing direct passage such as 5, and a conduit 6 provided with a pump 7 for the injection of water and / or a solvent alcoholic,

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a shear zone Z2, which comprises one or more malaxers of bilobed discs such as 8,

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a crushing and pressing zone Z_ {3}, which combines some crush modules consisting of a bit module with direct passage such as 9, with a decreasing current step upstream downstream, one or a few modules with steps inverted 10 to perform axial compression of the materials,

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some liquid phase extraction means located at the level of the area Z_ {3} and that combine a filter 11 and a liquid outlet 12 (put into service in the event that a deaf person is sought complementary to the cakes),

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and one terminal zone for collecting solid materials Z4, which It comprises a direct passage screwdriver modules 13 and an outlet 14 of the materials (cakes prepared for injection).

The injecting press symbolized in figure 3 it is a 90 t press, which comprises a feed hopper of cakes 15, an endless screw for transport and pressure 16, a pressure injection nose 17 and a module 18 of type known, opening by cats.

Example 1 Composition of the raw material used

In this example, sunflower cake is used bitornillo expression whose composition is as follows:

% percentage % % % % % % % compounds from minerals / proteins / lipids / cellulose/ lignin / hemicellulose / phenolics / hydration MS MS MS MS MS MS MS 10.8 5.2 26.7 25 16.7 3.9 14.9 4.3

Material Preparation

Hydration and homogenization of the material are performed with the help of the described screw device (Figures 1 and 2).

The speed of rotation of the screws is equal to 100 turns per minute and the temperature of the device is regulated and maintained at 100 ° C. The flow of raw material injected in the head is close to 24 kg / h.

Approximately 9 l / h of water are injected by the conduit 6 at the level of the zone Z_ {1}.

The hydrated material produced has a final moisture percentage of 24%, an equivalent average diameter D 50 of 0.35 mm (measured dry) and a cutting diameter D 95 0.8 mm. It comes in the form of a friable paste homogeneous

Injection

The injection is done with the help of the press of injecting described in figure 3. The injection parameters and Molding are as follows:

\ cdot

the maximum screw temperature 16 (TV),

\ cdot

mold temperature (Tm),

\ cdot

injection limit pressure (Pli),

\ cdot

the maintenance pressure (Pm1, Pm2),

\ cdot

the duration of the pressures of maintenance (t1, t2),

\ cdot

solidification duration (ts).

For the example treated, the value of these parameters are given in the following table:

Tm (ºC) Tv (ºC) Pli (b) Pm1 (b) Pm2 (b) t1 (s) t2 (s) ts (s) 103 fifty 40 30 30 25 fifty 90

The pieces formed are test pieces standardized type IA (ISO 527) used for the Tensile strength measurement, rectangular pieces of 60x10x4 mm used for flexural strength measurements and 90 mm diameter discs.

Maturation is performed at 50 ° C for 12 h.

The contraction observed in the course of the Maturation is 1.4% in the largest dimension of the piece rectangular.

The mechanical characteristics of the pieces, measurements on the TAXT2 Texturometer (Rhéo) after conditioning at 25 ° C and 60% humidity for 24 h is presented in the table next:

Flexion (Mpa) Traction (Mpa) Resistance Module Young Resistance Young's module 3.5 ± 0.5 497 ± 40 1.2 ± 0.17 110 ± 3

Example 2 Composition of the raw material

In this example, expression cake is used bottle whose composition is as follows:

% percentage % % % % % % % compounds from minerals / proteins / lipids / cellulose/ lignin / hemicellulose / phenolics / hydration MS MS MS MS MS MS MS 10.8 5.2 26.7 25 16.7 3.9 14.9 4.3

Material Preparation

In this example, the material does not suffer or complementary hydration or homogenization. He has a moisture percentage of 9%, a D 50 of 0.35 mm and a D 95 0.8 mm. It comes in a powdery form.

Injection

The conformation is done with the help of the Injection press described (Figure 3).

For the treated example, the value of the Injection parameters are given in the following table:

Tm (ºC) Tv (ºC) Pli (b) Pm1 (b) Pm2 (b) t1 (s), t2 (s), ts (s) 40 190 30 30 twenty 35

The pieces formed are the same as the described in example 1. Maturation is carried out in the same so as in example 1. The contraction in the course of the Maturation is very low and cannot be reliably evaluated.

The flexural strength of the pieces, measured in the TAXT2 Texturometer (Rhéo) after conditioning at 25 ° C and 60% humidity is presented in the following table:

Resistance (MPa) Young's module (MPa) 5.12 1147

Example 3 Composition of the raw material

In this example, spent cake is used in oil from the crushing sunflower seeds, whose Composition is as follows:

% percentage % % % % % % % compounds from minerals / proteins / lipids / cellulose/ lignin / hemicellulose / phenolics / hydration MS MS MS MS MS MS MS 10.0 7.0 35.6 1.0 22.3 5.2 18.5 5.7

The D_ {50} of the material is equal to 0.65 and its D 95 to 2.

Mechanical preparation and hydration of the material

Hydration, homogenization and division of the material are made with the help of the bitornillo device equipped with the profile illustrated in figures 1 and 2.

The speed of rotation of the screws is equal to 200 turns per minute and the device temperature is regulated and maintained at 100 ° C. The flow of raw material injected in the head is close to 23 kg / h.

Approximately 3 l / h of water are injected into the conduit 6 at the level of the zone Z_ {1}.

The hydrated material produced has a final moisture percentage of 5% and, dry, a D 50 of 0.4 mm and a D95 of 0.7 mm. It comes in the form of a paste friable.

Injection

The conformation is done with the help of the Injection press described.

For the treated example, the value of the Injection molding parameters are given in the following table:

Tm (ºC) Tv (ºC) Pli (b) Pm1 (b) t1 (s) ts (s) 65 115 110 100 5 13

The pieces formed are similar to those described in example 1.

Maturation is done in the same way as in example 1.

The contraction observed in the course of the Maturation is 1.7% of the length of the rectangular piece and 3% of its width

The mechanical flexural characteristics measured in the TAXT2 Texturometer (Rhéo) after conditioning 25ºC and 60% humidity for 24 h are represented in the table next:

Resistance (MPa) Young's module (MPa) 14.1 2156

Example 4 Composition of the raw material

In this example, an exhausted cake is used in oil from the crushing sunflower seeds, whose Composition is as follows:

% percentage % % % % % % % compounds from minerals / proteins / lipids / cellulose/ lignin / hemicellulose / phenolics / hydration MS MS MS MS MS MS MS 10.0 7.0 35.6 1.0 22.3 5.2 18.5 5.7

The D_ {50} of the material is equal to 0.65 and its D 95 to 2.

Mechanical preparation of the material

Hydration, homogenization and division of the material are made with the help of the bitornillo device equipped with the profile illustrated in figures 1 and 2.

The speed of rotation of the screws is equal to 200 turns per minute and the device temperature is regulated and maintained at 100 ° C. The flow of raw material injected in the head is close to 25 kg / h.

Approximately 0.5 l / h of water are injected into the conduit 6 at the level of the zone Z_ {1}.

The material produced has a final percentage of humidity of 2% and, dry, a D 50 of 0.4 mm and a D 95 of 0.7 mm It comes in the form of a friable paste.

Injection

The conformation is done with the help of the Injection press described.

For the treated example, the value of the molding injection parameters is given in the table next:

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Tm (ºC) Tv (ºC) Pli (b) Pm1 (b) t1 (s) ts (s) 56 115 110 40 5 13

The shaped pieces are similar to those described in example 1.

Maturation is done in the same way as in example 1.

The contraction observed in the course of the Maturation is 2.9% in the length of the rectangular piece and of 3.8% in width.

The mechanical flexural characteristics measured in the TAXT2 Texturometer (Rhéo) after conditioning at 25 ° C and 60% humidity are

Resistance (MPa) Young's module (MPa) 21.3 2531

Claims (10)

1. Molding process of an object by injection, in which a raw material is brought to the viscous or pasty liquid state by heating, it is injected under pressure into a mold and a hardening of the hardened material is carried out, characterized in that it is used, As raw material, a sunflower or rapeseed cake that has the following characteristics:

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bliss cake is at least partially unleashed so that your Weight content of oil is less than 25%,

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bliss cake is hydrated so that it presents a percentage of hydration significantly between 2% and 40%,

-

bliss cake has a particle size distribution such that the diameter D50 medium of its particles is between 0.1 mm and 1.2 mm

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the particles of the protein and fibrous constituents of said cake they are dispersed in a substantially homogeneous way.

2. Injection method according to claim 1, characterized in that an oil-depleted sunflower or rapeseed cake is used, which contains a maximum of 2% of oil, in particular the crushing of sunflower or rapeseed grains. 3. Injection process according to one of claims 1 or 2, characterized in that a cake is used which has a percentage of hydration substantially between 2% and 15%, said cake being heated to a temperature between 110 ° C and 200 ° C and sent to pressure to a cold mold or having a temperature below 65 ° C. 4. Injection method according to one of claims 1 or 2, characterized in that a cake is used which has a percentage of hydration substantially between 20% and 40%, said cake being heated to a temperature between 30 ° C and 100 ° C and sent to pressure to a heated mold at a temperature between 90 ° C and 140 ° C. 5. Injection method according to one of claims 1, 2, 3 or 4, characterized in that a cake of barked sunflower kernels or rapeseed is used. 6. Injection method according to one of claims 1, 2, 3 or 4, characterized in that a sunflower or rapeseed cake enriched with vegetable proteins is used. Method according to one of the preceding claims, characterized in that a cake is used that has a particle size distribution such that the average diameter D 50 of its particles is between 0.2 mm and 0.7 mm, and the diameter of cut D 95 is less than or equal to 0.8 mm. A method according to claim 7, characterized in that a divided, homogenized and at least partially desalted cake is used by passing the sunflower or rapeseed grains through a bitornillo device. 9. Method according to claim 8, in the which is used a bitornillo device comprising, of upstream downstream, if necessary means (6, 7) water injection and / or an alcoholic solvent, an area of shear (Z2) comprising at least one malaxador of shear (8), an area of crushing and pressing (Z 3), means (11, 12) for extracting the liquid phase, at least one module with inverted steps (10) to perform a axial compression of solid materials, and an outlet (14) of the solid matters. 10. Biodegradable, compostable and recyclable molded object, capable of being manufactured by application of the injection procedure according to claims 1 to 9, characterized in that it is essentially constituted by a protein matrix reinforced by vegetable fibers oriented according to one or a privileged directions and because it has a flexural resistance substantially between 3 and 30 megapascals.