FR2861081A1 - Formed composite comprising a polymer component and non-woven fabric made from annual or perennial plant fibre such as hemp, used e.g. in motor vehicles, fancy leather goods, building and furniture - Google Patents

Abstract

A formed composition (I) comprising (A) natural vegetable fibres from annual or perennial plants and (B) polar or non-polar polymers with melting points below 250[deg]C distributed on and/or in the fibres in a discrete or continuous manner, in which the fibres (A) are in the form of non-woven fabric with a fibre length of more than 30 mm. Independent claims are also included for (1) a method (M1) for the production of (I) by adding (A) to (B), fixing (B) on and/or in (B) by heating and possibly calendering at below 250[deg]C, forming the resulting sheet by compression at 100-250[deg]C and 50-1000 bar for 10 seconds to 5 minutes, and finishing by cold-pressing (2) unformed (possibly calendered) composite sheet (II) with the composition described for (I) (3) a method (M2) for the production of (II) by mixing (A) and (B) and fixing by heating (and optionally calendering) as in M1 (4) a method (M3) for the production of a composite composition by forming a sheet by compression as in M1.

Description

2861081 1

  COMPOSITION FORMED BASED ON MATERIALS OF VEGETABLE ORIGIN AND POLYMERS.

Field of the invention

  The present invention relates to formed compositions comprising raw materials of plant origin and polymers, their method of preparation and their applications.

  Prior art and technical problem.

  The compositions based on materials of natural plant origin have been the subject of many works in the world since the 1940s. In order to promote the materials that are the plants, they are integrated especially in the form of fibers in Polymer matrices that are used to produce composite finished products to replace metals in a wide variety of industrial uses.

  A major critical problem is to obtain the best possible adhesion to the fiber-matrix interface of these composites.

  This necessitates modifying, most often chemically, natural plant fibers which are by nature hydrophilic in order to make them compatible with the polymeric matrices used which are by nature hydrophobic (Natural Fiber Polymer Composites: a review; D.NABI SAHEB and JPJOG in Advances in Polymer Technology Vol 18, No. 4, 351-363, 1999) In US 2001/051242, there is disclosed the production of a composite composition comprising wood fibers and a composition of the invention. .doc 2861081 2 grafted polypropylene polymer. The fiber used is previously desiccated to less than 5000 ppm of water so that the grafted polypropylene (maleated polypropylene), the chemical modification agent of the fiber, is not deactivated by hydrolysis.

  Moreover, it is known from EP 319589 that thermoplastic composite compositions based solely on wood fillers such as those derived from wood fibers and not chemically modified, have the disadvantage of resulting in structures whose dispersion quality of fibers are not uniform and are difficult to implement. One way to remedy this is, according to EP 319589, to add to the wood fiber modified by drying, up to 50% of dried hemp fiber.

  In EP 1163093 there is disclosed in a very general manner parts consisting of recyclable raw material fibers bonded by a resin consisting of polyamides 11 or 12 or the corresponding copolyamides.

  WO 98/36024 also describes mixtures of 5 to 60% of flax fibers whose size has been reduced to less than 30 mm in biopolymer and polyamide matrices in order to obtain sustainable and ecologically recyclable materials by processes Injection molding. But these materials have limited mechanical strength.

  There is therefore a need for new composite materials at least as effective as current thermoplastic composites, including improved mechanical strength.

  SUMMARY OF THE INVENTION

  We have now found a composition which once formed has improved mechanical properties; this composition comprises natural fibers in the form of a nonwoven of fibers having a size greater than 30 mm and polymers whose melting points are lower than 250 C, said polymers being distributed on and / or in the fibers of discreet or continuous way.

  The object of the invention is to propose a composition formed comprising natural plant fibers derived from annual or multi-annual plants and polar or apolar polymers, whose melting points are lower than 250 ° C., said polymers being distributed on and / or in the fibers discretely or continuously, said composition being characterized in that the fibers are in the form of a nonwoven of fibers having a size greater than 30 mm.

  According to one embodiment, the nonwoven formed composition has a density of between 300 and 3000 g / m 2. Preferably, the natural fibers are chosen from hemp, flax, sisal, kenaf and jute.

  According to one embodiment, the weight percent of fibers in the nonwoven formed composition is in the range of 50% to 90%, preferably 70% to 95%.

  According to one embodiment, the polar polymer of the nonwoven formed composition is chosen from polymers or copolymers of polyamide 11, polyamide 12, polyamide 6 and 66 polymer blends of which the melting points are less than 250 ° C., the functionalized polypropylene polymers or their mixtures.

  According to another embodiment, the polar polymer is a copolymer of polyamide 11 and 12 optionally comprising mixed functionalized polypropylene polymers.

  In another variant, the polar polymer comprises a blend of polyamide 11 and 12 copolymer and maleized polypropylene polymer.

  According to another object, the invention relates to a thermoplastic formed composition having the characteristics described above, preferably whose flexural modulus are between 1000 and 10000 MPa.

  According to one embodiment, the composition formed comprises several thermoplastic zones, each zone having a flexural modulus different from that of the adjacent zone, the differences in modulus being in the range of 70 to 1500 MPa.

  Another subject of the invention relates to the process for preparing a composite composition having the characteristics described above comprising the steps of.

  contacting the natural fibers with the polymer; fixing the polymer to and / or in the fibers by heating and optionally calendering at a temperature below 250 C; R: \ Patents \ 21300 \ 21340. forming the sheet obtained in step b) by compression at a temperature between 100 ° C. and 250 ° C., at a pressure of between 50 bar and 1000 bar for a time of between 10 seconds and 5 minutes; and finishing by cold pressing.

  According to a variant of the process, the natural fibers are undried.

  According to another variant, in the step of contacting the natural fibers with the polymer of the above process, the polymer is dispersed on the fibers in the form of powder, particles or granules.

  According to one embodiment, the method comprises an additional step of integrating the powder polymer into the mesh formed by the fibers by an electric field, after the step of bringing the natural fibers into contact with the polymer.

  According to another object, the invention relates to the use of the compositions formed described above in the fields of automotive, leather goods, building, furniture.

  According to yet another object, the invention relates to an optionally unmolded composite sheet comprising natural plant fibers derived from annual or multi-annual plants and polar or apolar polymers, whose melting points are less than 250 C, said polymers being distributed on and / or in the fibers in a discrete or continuous manner, said sheet being characterized in that the fibers are: in the form of a nonwoven of fibers having a size greater than 30 mm.

  In other embodiments, the unformed composite sheet above is provided with the features of the compositions described above.

  According to another object, the invention relates to a process for preparing an unformulated composite sheet optionally calendered as described above comprising the steps of; Contacting the natural fibers with the polymer; Fixing the polymer on and / or in the fibers by heating and possibly calendering at a temperature below 250 C.

  According to other variants, the process for preparing the unformed composite sheet optionally calendered above has the characteristics described in the variants of the process for preparing the composite composition described above.

  According to another object the invention relates to the use of an unformed composite sheet optionally calendered as described above for the preparation of a composition formed as described above.

  According to another object the invention relates to the process for preparing a composite composition comprising the steps of; forming an unformed, optionally calendered composite sheet as described above by compression at a temperature of between 100 ° C. and 250 ° C., at a pressure of between 50 bar and 1000 bar for a period of from 30 ° C. to 250 ° C. d o c 2861081 7 duration between 10 seconds and 5 minutes; and finishing by cold pressing.

Detailed description of the invention.

  The fibers used in the invention are all natural plant fibers derived exclusively from annual or bi-annual plants such as flax, hemp, sisal, kenaf, jute, etc.

  The preferred fibers are those from hemp.

  These fibers do not undergo any particular treatment before they come into contact with the polymers and are therefore naturally in the form of long fibers, the size of which is greater than 30 mm, in particular 30 to 150 mm.

  Long fibers with a size between 50 and 150 mm or more are preferred.

  It is not necessary within the scope of the invention to reduce the initial water content of the fibers to levels below 5000 ppm as described in the prior art.

  On the contrary, the fibers are used with their initial water content which is between 10 and 15% to prevent their alteration and in particular the shortening of their size.

  The natural fibers according to the invention are in the form of a so-called non-woven structure.

  The nonwoven is in particular a manufactured sheet, consisting of directionally oriented or randomly oriented fiber fleece or web bound by friction and / or cohesion and / or adhesion, excluding paper and products obtained by weaving, knitting, tufting stitching incorporating binding yarns or filaments or felts by wet embossing whether or not they are R: \ Patents \ 21300 \ 21340. d oc 2861081 8 needles (from The Great Terminology Dictionary).

  The density of the nonwoven used is between 5 200g / m2 and 3000g / m2, preferably 1000 to 2000g / m2.

  The polymers used for the invention have a melting point of less than 250 ° C. in order to respect the thermal stability limits of the fibers.

  The polymers may be polar or apolar type. The apolar polymers are selected from different grades of polypropylene.

  The polar polymers are selected from the following different compounds; polymers of polyamide 11 (PA11) or of polyamide 12 (PA12) whose melting points are at about 175 ° C. to 185 ° C., as well as the various corresponding PA11 & 12 copolymers whose melting points are in the range of 85 ° C. C to 160 C and whose fluidities (MFI) in the molten state can vary from 1 to 60 according to the molecular weights obtained.

  Preferred polar or apolar polymers have fluidity indices (MFI) ranging from 4 to 50.

  Polyamide polar copolymers 11 and 12, particularly those referenced under codes H106 or 2513 of the ATOFINA copolyamide range, will be preferred.

  It is also possible to use mixtures of polymers of polyamides 6 and 66 whose melting points are less than 200 ° C., in contrast to pure PA6 or PA66 polymers whose melting points are greater than 240 ° C. For example, a PA6 / copolymer may be mentioned. 66 such as the CAPRON CA 73 ZP from HONEYWELL.

  In another embodiment, the polar polymer may comprise a functionalized polypropylene polymer.

  A type of functionalized polymer such as maleized polypropylene (PP-ma) is conventionally obtained by grafting 0.03 to 5% by weight of maleic acid onto polypropylene. Grafting rates of 0.1 to 4% by weight will be preferred. As a preferred product, mention may be made of Atofina's reference product 18732P.

  The polymers and copolymers mentioned above may be used alone or in mixtures in all proportions in binary or ternary formulas.

  According to a preferred embodiment, the polar polymer is a mixture of copolymer of polyamide 11 and 12 and maleized polypropylene polymer (PP-ma). Indeed, the PP-ma, because of its greater melt viscosity than that of the copolymers of polyamides mentioned, reinforces the fiber coatings by the more fluid polyamide polymers. Thus we obtain a better adhesion between the fibers which ensures a good cohesion in the mass of the interstitial polymers. The overall mechanical strength of the composite compositions obtained (stiffness, resistance to deformation) is thus improved.

  Polymeric polymers containing 50% to 70% of polyamide 11 and 12 copolymers and 30% to 50% of maleicized polypropylene polymer will preferably be used.

  According to one embodiment, the fibers represent in the final formed composition more than 50% by weight R: \ Patents \ 21300 \ 21340. total and preferably 50 to 90%, or from 70 to 95% of the total weight of the composition. Depending on the respective proportions of the blend of copolymers of polyamide 11 and 12 and maleized polypropylene polymer (PP-ma), and the percentage of fibers used, the density of the sheets of composite materials obtained and their rigidity can be modulated (see FIG. results tables I).

  The (co) polymers used may be in dry form such as particles, powders or granules whose sizes may preferably be less than 200 microns to allow a good distribution on and in the nonwoven.

  They may also be in the form of fibrils incorporated with the fibers, or in the form of spraying liquids above the nonwovens.

  Depending on the dry or liquid physical form of the polymer, the dosage of the polymeric formulation used, the distribution of the polymer on or in the fibers of the nonwoven may be either discrete or continuous.

  With a discrete distribution of the polymers, for example in the form of granules on the nonwoven, one will finally obtain a composition formed porous or aerated.

  With a continuous distribution of the polymers in the form of powder, a sealed formed composition will be obtained.

  On the other hand, by varying the viscosity of the polymers used, it will be possible to modulate the concentration gradient of the polymers within the nonwoven fiber network.

  In all the cases mentioned above, it will be possible to modulate and optimize the flexural strength properties of R: \ Brev ets \ 21300 \ 21340. The process for preparing the composition formed comprises, first of all, the step a) of bringing the natural fibers into contact with a polymer. whose melting point is less than or equal to 250 c; the contacting is performed on the nonwoven structure by dusting or distribution of the polymer on each of the nonwoven surfaces.

  After each distribution, it is possible to carry out a step of integrating the polymer into the cells of the nonwoven fabric by known methods such as electric field methods such as the Fibrolin method.

  The next step b) is to fix the polymer on and / or in the fibers by heating and possibly calendering.

  The calendering is carried out by techniques known to those skilled in the art such as calender with two cylinders cooled or with three cylinders for heating and cooling the product in a single pass.

  The heating can be carried out by various techniques by blowing hot air or infrared ramps or by passing through a hot band press.

  The heating temperature, below 250 ° C., is that which makes it possible to melt the polymer on or in the fibers while respecting the stability limits of the natural fibers. Depending on the fluidity of the polymer, it may be maintained at the surface or also spread between the fibers of the nonwoven fabric.

  Thus, this process step makes it possible not to degrade the fibers from the manufacture of the powder and fiber mixtures with the sticky and hot masses of the polymers.

  At this stage of the process, there is obtained a non-formed composite sheet optionally calendered stable and not thermally degraded as an intermediate product, another object of the invention, to obtain the composition formed as the final product.

  To obtain the final product of the invention, the process then comprises a step c) of compression forming of the calendered sheet obtained in the preceding step, at a temperature of between 100 ° C. and 250 ° C., at a pressure comprised between 50 and 1000 bar for a period of between 10 seconds and 5 minutes; According to a preferred embodiment, the compression step is carried out at a temperature suitable for the complete melting of the polymers, by compression between 20 and 40 bar for 2 to 5 minutes or else by compression between 100 and 275 bar for 30 seconds at 1 minute.

  Step c) is followed by a finishing step d) by cold pressing to remove the calories and allow the manipulation of the resulting formed composition. This step is preferably carried out at the same pressure as in the preceding step c) for a period of between 2 and 5 minutes.

  The compositions formed according to the invention are recyclable. For example, the pieces formed at the end of the life cycle or the scrapes resulting from the forming can be R: \ Brev ets121300 \ 21340. d oc 2861081 13 again transformed into granules which are reincorporated into the preparation of new types of composite materials.

  The formed compositions obtained may be in the form of sheets or plates of varying thickness and surface and very varied depending on the chosen applications such as interiors of car doors, luggage rack backboards, trunk supports, transport seats or light and rigid furniture.

  Depending on the parameters of temperature, pressure and compression time, several different zones can be obtained on the same sheet or plate, each zone having a modulus of flexion or stiffness different from that of the adjacent zone, the module difference being able to vary. from 70 MPa to 1500 MPa or from 500 to 1500 MPa for the same polymer formulation.

  The compositions formed according to the invention can be used in the fields of automobile, leather goods, building, interior or exterior furnishing such as garden furniture, indoor furniture, light and rigid furniture, preformed cabinets.

  In particular, when the composite material has both areas of different plasticity or rigidity, it can be used to prepare seamless, one-piece luggage or shoes.

  The unformed, optionally calendered composite sheet is an intermediate product which is in the form of a flexible sheet which can be stored before being converted into final product in various forms, for example in the form of rolls.

Examples.

  The following examples illustrate the present invention without however limiting its scope.

  On non-woven hemp sheets having a density of 500 g / m 2, by dusting at a rate of 10% or 15% on each side, 20% or 30% by weight of polar polymer powders consisting of different% PAll & 12 are added. (1 / H106) mixed with maleicized PP whose grafting rate is 0.15% by weight (2 / 18732P). The respective melting points are 110 C for (1) and 125 C for (2) (see Table I).

  After each dusting, an infrared fixing then makes it possible to fix the powders to the hemp fibers by slight melting without pressure or degradation. The adjustment of the melting calendering is done by visual observation by obtaining the melting of the powders or the polymer grains without the decomposition of the hemp fibers (release of burnt odors and blackening).

  Then, the plates are compressed under 50 bar pressure at 180 C for 5 minutes and then under cold pressure for finishing.

  The plates (350 × 350 mm 2 of variable thickness) are then tested in apparent density, flexural modulus (see the results in Table I): R: \ Patents \ 21300 \ 21340.doc 2861081 15 The three-point bending measurements were made from bars 100X10Xep. mm3 die-cut on the plates. The measurements were made on ZWICK 1465 robotic dynamometer by setting the supports at 16X average thickness, ie about 32 mm of range. The speed has been chosen at 1 mm.min-1 (thickness / 2). The method is therefore related to ISO 178 but can not completely replace it.

  Density measurements were made by simple weighing of a 50 mm diameter disc cut on the die plate.

  The results are reported in Table I.

Table I

  Conditions 100 Bar & 160 C 275 Bar & 180 C (1) (2) Flexion Density Flexion Density PA PP-ma MPa MPa H106 18732 Addition 20% in weight of polymers 0% 100% 73 0.53 1078 0.76 30% 70% 69 0.57 1461 0.94 50% 50% 47 0.53 1211 0.82 70% 30% 646 0.95 1231 0.84 100% 0% 487 0.90 1072 0.85 Addition 30% in weight of polymers 0% 100% 99 0.57 1208 0.74 30% 70% 100 0.51 1261 0.85 50 % 50% 70 0.57 1347 0.92 70% 30% 84 0.74 1333 0.93 100% 0% 332 0.59 973 0.76 R: \ B Coated \ 21300 \ 21340. doc

Claims (1)

16 Claims.   1. Composition formed comprising natural plant fibers derived from annual or multi-annual plants and polar or apolar polymers, whose melting points are below 250 ° C., said polymers being distributed on and / or in the fibers in a discrete or continuous manner said composition being characterized in that the fibers are in the form of a nonwoven of fibers having a size greater than 30 mm.   The composition formed according to claim 1 wherein the nonwoven form has a density of between 300 and 3000 g / m 2.   3. A composition formed according to claim 1 or 2 wherein the natural fibers are selected from hemp, flax, sisal, kenaf, jute.   4. Composition according to one of claims 1 to 3 wherein the weight percentage of fibers in the composition is in the range of 50% to 90%, preferably 70% to 95%.   5. Composition according to one of claims 1 to 4 wherein the polar polymer is selected from polymers or copolymers of polyamide 11, polyamide 12, polyamide polymer blends 6 and 66 whose melting points are less than 250. C, functionalized polypropylene polymers or mixtures thereof.   6. A composition formed according to one of claims 1 to wherein the polar polymer is a polyamide copolymer 11 and 12 optionally comprising mixed functionalized polypropylene polymers.   7. Composition formed according to one of claims 1 to 6 wherein the polar polymer comprises a mixture of copolymer of polyamide 11 and 12 and maleated polypropylene polymer.   A thermoplastic formed composition according to any one of claims 1 to 7.   9. Thermoplastic formed composition according to claim 8, wherein the flexural modulus are between 1000 and 10000 MPa.   10. A composition formed according to one of claims 8 or 9 comprising a plurality of thermoplastic zones, each zone having a flexural modulus different from that of the adjacent zone, the differences in modulus being in the range of 70 to 1500 MPa.   A process for preparing a composite composition according to any one of claims 1 to 10 comprising the steps of; a) contacting the natural fibers with the polymer; b) fixing the polymer on and / or in the fibers by heating and optionally calendering at a temperature below 250 C; (C) forming the sheet obtained in step b) by compression at a temperature of between 100 ° C. and 250 ° C., at a pressure of between 50 bar and 1000 bar for a period of time between 100 ° C. and 250 ° C. duration of between 10 seconds and 5 minutes; and d) cold pressure finishing.   The method of claim 11 wherein the natural fibers are undried.   13. Method according to one of claims 11 or 12 wherein in step a) the polymer is dispersed on the fibers in the form of powder, particles or granules.   The method of any one of claims 11 to 13 including a further step of integrating the powdered polymer into the fiber mesh after step a).   15. Use of the compositions formed according to any one of claims 1 to 10 in the fields of automotive, leather goods, building, furniture.   16. Unformulated sheet optionally calendered comprising natural plant fibers from annual or multi-annual plants and polar or apolar polymers, whose melting points are lower than 250 C, said polymers being distributed on and / or in the fibers of discrete or continuous manner, said sheet being characterized in that R: \ Patents \ 21300 \ 21340. that the fibers are in the form of a nonwoven of fibers having a size greater than 30 mm.   17. Sheet according to claim 16 which has the features according to one of claims 2 to 10.   18. A process for preparing an unformulated composite sheet optionally calendered according to claim 16 or 17 comprising the steps of; a) contacting the natural fibers with the polymer; b) fixing the polymer on and / or in the fibers by heating and possibly calendering at a temperature below 250 C. 19. The method of claim 18, which has the characteristics according to one of claims 12 to 14.   20. Use of a non-shaped optionally calendered composite sheet according to claim 16 or 17 for the preparation of a composition formed according to one of claims 1 to 10.   A process for preparing a composite composition according to any one of claims 1 to 10 comprising the steps of; forming a sheet according to claim 16 or 17 by compression at a temperature of between 100 ° C. and 250 ° C., at a pressure of between 50 bar and 1000 bar for a period of time between 10 ° C. and 250 ° C. 2861081 20 seconds and 5 minutes; and finishing by cold pressing. R: \ Patent \ 21300 \ 21340.doc