Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08H—DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS
  • C08H99/00—Subject matter not provided for in other groups of this subclass, e.g. flours, kernels
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L101/00—Compositions of unspecified macromolecular compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L99/00—Compositions of natural macromolecular compounds or of derivatives thereof not provided for in groups C08L89/00 - C08L97/00
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2300/00—Characterised by the use of unspecified polymers
  • C08J2300/16—Biodegradable polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
  • C08J2367/04—Polyesters derived from hydroxy carboxylic acids, e.g. lactones
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2399/00—Characterised by the use of natural macromolecular compounds or of derivatives thereof not provided for in groups C08J2301/00 - C08J2307/00 or C08J2389/00 - C08J2397/00
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/05—Alcohols; Metal alcoholates
  • C08K5/053—Polyhydroxylic alcohols

Definitions

• the present invention relates to the field of biodegradability of plastics and relates to the development of composite materials based on polymers and plasticized cereal materials (also called cereal fillers). These biodegradable materials are intended to replace the synthetic plastics used in many fields of activity such as cosmetology, pharmacy, agrifood or agriculture, for example as a packaging product.
• Biodegradable materials capable of being substituted for synthetic plastics are known in the prior art.
• biodegradable is meant in the context of the present invention, any biological degradation, physical and / or chemical nature at the molecular level of substances by the action of environmental factors (in particular enzymes derived from microorganisms metabolism process) .
• biodegradable materials resulting from a mixture between a polymer and a surface-modified starch described for example in US Patents No. 1,485,833, and No. 1,487,050, No. 4,021,388 , No. 4 125 495 and European patent No. 45 621.
• This chemical modification of the surface state of the starch makes it possible to create ether or ester functions or to make the surface of the starch hydrophobic.
• materials formed of a polymer and a destructured starch that is to say having undergone a specific pretreatment with a destructuring agent such as urea, hydroxides of alkali or alkaline earth metals. , as described in European Patent Nos.
• biodegradable materials consisting of starch, polymers other than polypropylene and additives
• additives can be unsaturated chemical compounds such as natural rubber or elastomers as described in European patent No. 363,383, or vegetable materials such as wood flour or cellulose as described in European patent No. 652,910, or a plasticizer such as polyols, glycerol and / or its derivatives - diglycerol, polyglycerol - calcium chloride or ethers as described in European patents No. 473 726, No. 575 349 and US No. 5,393,804.
• polymers envisaged mention may be made of poly (ethylene / vinyl alcohol) and poly (ethylene / acrylic acid) proposed in European patents No. 400 532, No. 413 798 and No. 436 689, or copoly aliphatic erasers and polyesters as proposed in European patent No. 539 541, or polyethylene low density as proposed in PCT patent application No. WO 9115542 and US patent 5,162,392.
• biodegradable materials based on polymer and cereal flour This material, which is the subject of the PCT international patent application published on March 16, 2000 under the number WO00 / 14154, is distinguished from the biodegradable materials of the prior art by the fact that it is obtained from cereal flour and not from starch and that said cereal flour does not undergo any treatment such as total gelatinization, destructuring of the surface of the starches or a modification of this surface.
• the process described in international patent application WO 00/14154 consists in mixing together, in a first step, the cereal flour and the polymer.
• This first step is called “compounding” and is generally carried out by twin-screw extrusion, in the presence of various compatibilizing agents or not.
• FIBERPLAST ® a range of products based on this concept.
• PP polypropylene
• Table 1 materials with new properties.
• Fiberplast PP X means a material containing polypropylene and X% by total weight of corn flour- and obtained according to the process which is the subject of international patent application WO 00/14154.
• cereal flours and the polymers used in the biodegradable materials are too far apart. others at the physico-chemical level and that they have different properties.
• cereal flour is hydrophilic while synthetic thermoplastic polymers are generally lipophilic.
• size of the particles constituting a cereal flour is between 0.1 and 500 ⁇ m while the size of the polymers which can be used is of the order of 2 to 3 mm.
• the rheological and thermal characteristics of cereal flour and polymers in the extrusion processes are too different.
• the Applicant has hypothesized that the quality of the mixture between the cereal flour and the polymer and its stability at the extruder outlet - single and / or twin-screw - are governed by two laws which are: - thermal similarity in solid phase, according to which the homogeneous mixture of chemically incompatible products is conditioned by an equivalent heat transfer in the solid phase, allowing simultaneous fusion during the extrusion processes; - the rheological similarity, according to which the mixing of two products can only be done if their viscosity is similar at a given temperature.
• the Applicant after studying the rheological and thermal behavior of the polymers used, sought to identify a transformation of the cereal material allowing it to approach from the physico-chemical point of view the properties of said polymers with which it is associated in the biodegradable materials.
• Authors have worked on the production of cereal products, mainly based on starch, which can be used for the production of injected parts. They then use different plasticizers, the objective of which is to obtain a melt of starch during the extrusion. Their work constitutes the starting point for the transformations of the cereal material envisaged by the Applicant.
• the work of the Applicant has made it possible, on the one hand, to compare two methods of characterizing a plastic material.
• the first consists in reading a melting index profile (MFI), a routine analysis for plastics professionals.
• MFI melting index profile
• WLF equations viscosity function
• the second, heavier and slower, consists of transforming the material into extrusion and recording the pressure drops by capillary rheometry.
• the treatment of the Navier-Stokes equations for an incompressible fluid in laminar, permanent and established regime makes it possible to obtain the viscosities of the material as a function of the shear.
• the results showed the convergence of the 2 methods: it is possible to predict, from an MFI measurement, what will be the viscosity of the material in extrusion for any temperature, shear and pressure.
• the Applicant sought to prepare a cereal material having a viscosity similar to that of the polymer used during the extrusion. More particularly, it verified that, by prior plasticization of the cereal material, it is possible, during the final extrusion, to compatibilize a polymer with the defined rheology with an adequate cereal material.
• Biodegradable material thus obtained can be used in particular for industrially obtaining biodegradable films 10 ⁇ m thick and exhibits remarkable biodegradability and resistance properties, as described in the examples below.
• the present invention therefore relates to a biodegradable material comprising a mixture of at least one polymer with at least one cereal filler and optionally one or more acceptable additives characterized in that the polymer and the cereal filler are close in their rheological and thermal properties.
• cereal filler any cereal material plasticized by means of a plasticizer.
• cereal material is meant, in the context of the present invention, plant materials derived from cereals the compositions of which, according to the various basic ingredients, are as follows (weight percentages): - water between 0 and 20% ,
• the corn cereal material of the example is a flour obtained following the additional grinding of a coarse corn semolina.
• the grain size of this corn flour is shown in Figure 5.
• starch which is an important element in a flour
• this consists of a mixture of two glucose polymers: amylose and amylopectin.
• the ratio between these two molecules is different according to cereals and varieties for the same cereal.
• amylose / amylopectin ratio can be modified by genetic transformations using the nucleotide sequences of the genes involved in the metabolism of starch or by the use of the natural genetic variability of plant species.
• the biodegradable material of the invention is remarkable in that it comprises all of the constituents of a cereal material and not only of starch.
• polymer in the context of the present invention any plastic material and, more particularly, any thermoplastic material. It is advantageously chosen from the following groups: - synthetic polymers: family of polyolefins (high and low density polyethylene, polyprolylene, with MFIs (melting flow index from 0.1 to
• PVC family of styrenics (standard PS, expanded or shock), ...
• biodegradable polymers family of polylactic acids (PLA), family of butanediol copolyester, adipic and tereph alic acids, family of copolyester - starch composites, family of lactones and polycaprolactones, ...
• PLA polylactic acids
• butanediol copolyester family of butanediol copolyester
• adipic and tereph alic acids family of copolyester - starch composites
• family of lactones and polycaprolactones family of lactones and polycaprolactones
• plasticizer in the context of the present invention is meant a natural or synthetic molecule used to lower the melting temperature of a polymer.
• the plasticizer makes it possible to plasticize the cereal material.
• the plasticizers which can be used in the context of the biodegradable material of the invention are chosen from the group consisting of glycerol and its derivatives such as di or polyglycerol, castor oil, linseed oil, rapeseed oil, sunflower oil, corn oil, polyols, urea, sodium chloride and mixtures thereof.
• acceptable additives in the context of the present invention, more particularly means a natural or synthetic molecule providing a characteristic of appearance to the product, such as color or texture, of rigidity, facilitating the usual plastics processes, such as lecithin serving as a release agent in the injection process, or facilitating the biodegradability of polymers, in particular.
• the rate of plasticization of the cereal load must be between 10 and 40%.
• the polymer used is a biodegradable copolyester and the cereal material of corn flour
• a rate of plasticization by glycerol of between 20 and 30% is advantageously used, while the use of polycaprolactones as polymers requires '' use a higher plasticization rate, centered on 35%.
• Those skilled in the art have sufficient teaching in this document to modify the plasticization rates as a function of the polymers used without demonstrating an inventive effort.
• the present invention also relates to the use of a biodegradable material as defined above for the preparation of plastic films and / or injected plastic parts.
• the present invention relates, on the one hand, to a plastic film made entirely or in part of said biodegradable material and, on the other hand, to an injected plastic object made entirely or in part of said biodegradable material.
• such objects can be cups, bottles, pots, strings, sachets, tubes, etc.
• the biodegradable material which is the subject of the present invention comprises, for the production of plastic films:
• the biodegradable material which is the subject of the present invention comprises, for the production of injected plastic parts:
• the present invention also relates to a method for compatibilizing a polymer with a cereal material in order to produce a biodegradable material as defined above.
• Said method advantageously comprises the following steps: (i) determining the viscosity of the polymer at a working temperature,
• step (ii) adapt the viscosity of the cereal material to that of the polymer determined in step (i) at the same temperature
• step (i) of the present process is carried out by capillary rheometry.
• the work of the Applicant has made it possible to show that the viscosity of a polymer can be evaluated both in the laboratory by evaluation of the melt index and during the process (ie actual measurements) by online recordings. pressure losses by capillary rheometry.
• Step (ii) consists of plasticizing the cereal material using a plasticizer as defined above.
• the adaptation of the viscosity of the cereal material to that of the polymer can also be influenced by the particle size of said cereal material and / or by the physical state of the starch granules in said cereal material.
• a pregelatinization step may be necessary before the step of plasticizing the cereal material.
• the thermal similarity can be assessed in step (iii) by verifying that the polymer and the suitable cereal material exhibit simultaneous melting during the extrusion processes.
• the present invention further relates to a process for the preparation of a biodegradable material, a plastic film or an injected plastic object as defined above.
• a method for the preparation of a biodegradable material, a plastic film or an injected plastic object as defined above comprises a prior step of co-patibilization of the cereal material with the polymer according to a method for compatibilizing a polymer with a cereal material as defined above.
• the process for preparing a biodegradable material, a plastic film or an injected plastic object presents at least one additional stage of production of the desired product according to one of the usual processes of the plastics industry with mixing of the compatibilized cereal material and of the polymer.
• the process for preparing a biodegradable material which is the subject of the present invention is remarkable in that it makes it possible to avoid the physical step of compounding the processes of the prior art.
• FIG. 1 shows the evolution of the stress at the wall ⁇ ⁇ as a function of the apparent shear ⁇ ' a (in log-log);
• - Figure 2 shows the evolution of the viscosity of the biodegradable copolyester as a function of the actual shear;
• - Figure 3 shows the comparison of experimental and calculated viscosities of the biodegradable copolyester;
• FIG. 4 represents the rheogram of the biodegradable copolyester obtained by coupling the MFI values obtained at 150 ° C. under different constraints to the values recorded online;
• FIG. 5 shows the grain size of the corn flour used in the experimental part and obtained following additional grinding of a coarse cornmeal
• FIG. 6 presents an example of configuration of the screws of a twin-screw extruder to prepare a thermo-elastic flour (FTP) capable of replacing up to 50% w / w of biodegradable copolyester;
• FTP thermo-elastic flour
• FIG. 7 shows a diagram of the process for preparing the thermoplastic flour
• FIG. 8 shows the viscosity-shear rheogram of the thermoplastic flour used in the context of the present invention (clear crosses) and compared to that of a pregelatinized flour at the same rate of plasticization (dark crosses);
• FIG. 10 shows the viscosity of FTP obtained at 150 ° C for different shear values
• FIG. 10 represents the evaluation of the overall viscosity of the FTP obtained by coupling the values of MFI obtained at 150 ° C. under different constraints to the values recorded online;
• Figure 11 compares the overall viscosity functions of the biodegradable copolyester and an FTP plasticized to 22% at 150 ° C, over the entire shear range;
• Figure 12 shows the view from two angles (respectively Figure 12A and Figure 12B) of the thermal progression measured for high density polyethylene (black curve) and low density polyethylene
• FIG. 13 shows the comparative spatio-temporal visualization between polyester and 10% and 40% glycerol FTP
• FIG. 14 shows the comparative spatio-temporal visualization between a FTP at 30% corn oil (black curve), polyester (light gray curve) and low density polyethylene (dark gray curve)
• - Figure 15 shows the mechanical properties of the 12 ⁇ m films obtained from FTP.
• FIG. 15A shows the evolution of the longitudinal mechanical characteristics of the films as a function of the% of FTP
• FIG. 15B shows the evolution of the transverse mechanical characteristics of the films as a function of the% of FTP.
• MFI melt index
• the MFI values of the biodegradable copolyester were measured at different temperatures and are collated in Table 2 below (average value of 10 measurements and range (%)).
• the capillary rheometry technique consists in continuously measuring the viscosity of a molten phase ⁇ at the output of a twin-screw extruder through a capillary according to the input parameters: temperature, screw speed, flow rate.
• the pressure drops ⁇ P are measured in this capillary by 2 pressure sensors (upstream and downstream).
• K consistency index (Pa.s m )
• m pseudoplasticity index (m ⁇ l)
• the initial hypotheses for this study are: - an established permanent flow
• Table 4 presents the pressure drop records (bars) for a mass flow range from 20 to 60 kg / h, 2 screw speeds, and a temperature of 150 ° C (lots 05.09.02): Table 4
• FIG. 1 represents the evolution of the stress at the wall ⁇ ⁇ as a function of the apparent shear ⁇ ⁇ (in log-log).
• the slopes indicate the pseudoplasticity indices m.
• the pseudoplasticity index at 100 rpm is 0.4872 and at 160 rpm is 0.5827.
• the behavior of the biodegradable copolyester is very pseudoplastic: decrease in viscosity with shear.
• the differential behavior due to the screw speed can be explained by a slight depolymerization at high speeds: the difference fades with shear.
• FIG. 3 shows that the viscosity of the biodegradable copolyester changes little for a screw speed of between 100 and 130 rpm, at equivalent shear. Using WLF relationships, it is possible to calculate the theoretical viscosities corresponding to the shears encountered in extrusion (Table 5).
• FIG. 4 clearly shows a shear-thinning behavior of the biodegradable copolyester and a correct adequacy between the MFI measurements and those in line, in terms of viscosity continuity.
• the viscosity function of the biodegradable copolyester responds to:
• the first consists in reading a melting index profile (MFI), a routine analysis for plastics professionals.
• MFI melting index profile
• WLF equations The analysis of the rheological behavior allowed us to transform the MFI values into an evaluation of the viscosity function (WLF equations).
• the second, heavier and slower, consists of transforming the material into extrusion and recording the pressure drops by capillary rheometry.
• the processing of Navier-Stokes equations for an incompressible fluid in a laminar, permanent and established regime, allows the viscosities of the material to be obtained as a function of the shear.
• the same approach will now be applied to the processed cereal material.
• the aim will be to produce a vegetable material of viscosity similar to the plastic to be loaded, within a defined shear range.
• glycerol or propanetriol
• the objective is to achieve a homogeneous mixture of corn flour - glycerol in twin-screw extrusion.
• the properties of this mixture will be analyzed later.
• the extruder used consists of two co-rotating screws placed in sheaths surrounded by heating elements. This machine allows among other things to mix and melt different constituents thanks to a thermal contribution induced by heating and by mechanical shearing.
• the mechanical work is provided by modular screw elements which are positioned on the 2 shafts: the set of elements is called
• the size of the flour particles is important: it conditions the heat exchange.
• the particle size distribution corn flour used is shown in the figure
• the extrusion conditions are such that there is a Specific Mechanical Energy (SME) of 100 to 300 W.h / kg and a temperature between 80 and 160 ° C for the material leaving the die.
• SME Specific Mechanical Energy
• the compatibilization of a polymer X and a cereal load must comply with the following protocol: determine by capillary rheometry the viscosity of the polymer to be loaded into the extruder at a working temperature,
• MFI measurements are carried out at 150 ° C. under different constraints.
• the data are collated in Table 8 below (plasticized FTP at 22%).
• FIG. 11 compares the overall viscosity functions of the biodegradable copolyester and of a 22% plasticized FTP at 150 ° C., over the whole shear range.
• Plasticized FTP between 20 and 30% can be used for the production of thin films (15 ⁇ m) with the biodegradable copolyester. Other percentages are being studied with other polymers: for example, the compatibilization of FTP with polycaprolactones (PCL) requires a level of plasticization centered around
• the first part of the study consisted in studying the rheological behavior of a plastic material and in preparing a cereal material compatible with the polymer to be loaded. In this study, only the melted phases are taken into account. However, as indicated in paragraph I.l.l.a, solid granules obtained from FTP products are used. The characterization of the solid - molten phase passage, which intervenes in the extrusion process, is therefore necessary: it involves the equation of the heat transfer in transient regime.
• Figure 12 shows the view from two angles
• FTP can be produced with different plasticizers: di and polyglycerol, glycerol ester, vegetable oils (corn, rapeseed, castor oil, ). Regardless of the rheological constraints, we can compare the thermal flow of an FTP at 30% corn oil with low density polyethylene and polyester. The result of this study is presented in Figure 14. The curves obtained for FTP at 30% corn oil and for low density polyethylene are very similar. Consequently, the thermal compatibility between these two components is closer than that observed between a 30% FTP of corn oil and polyester. Thus, knowing the thermal properties of the plastic resin to be loaded, and by a judicious choice of the plasticizer, it is possible to comply with the 2 “process” constraints that are thermal and rheological identities.
• the measurements are made with a LLOYD LR5K device, in traction mode: 0.1 N preload, traction speed 100 mm / min, on rods of 4 +/- 0.1 mm in diameter, for a basic length of test tube 80 mm.
• the characterization relates to 3 levels of glycerol plasticization; the results are collated in table 12 below.
• the measurements are made with an LLOYD LR5 device, in traction mode: 0.1N preload, traction speed 100 mm / min, for a base length of test tube of 80 mm and a width of 20 mm.
• FIGS. 15A and 15B The results on a 12 ⁇ m film with loading rates of 30 to 50% are presented in FIGS. 15A and 15B (identical inflation parameters, in particular inflation rate).
• Table 13 presents the results observed on a 12 ⁇ m film loaded with 40% FTP.

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