POLYAMIDE-BASED COMPOSITION, ARTICLE OBTAINED THEREFROM, AND USES THEREOF

Abstract

The invention relates to a composition comprising at least one first polyamide, conforming to the formula MXD.10 or MXD.10/Z and having a melting temperature Tf.sub.1, and at least one second polyamide.

Said at least second polyamide has a melting temperature Tf.sub.2 such that Tf.sub.140 C.Tf.sub.2<Tf.sub.1+20 C.

The invention likewise relates to an article obtained from such a composition, to a method of shaping such an article, and to the use of such a composition and of such an article.

Claims

1. A composition comprising: at least one first polyamide represented by formula MXD.10, resulting from a condensation of (a) meta-xylylenediamine (MXD) or a mixture of MXD and para-xylylenediamine (PXD) and (b) sebacic acid, wherein the MXD is predominant in the mixture of MXD and para-xylylenediamine (PXD), and said at least first polyamide has a melting temperature Tf.sub.1, and at least one second polyamide having a melting point Tf.sub.2, for which Tf.sub.140 C.Tf.sub.2, wherein said at least one second polyamide is PA11, wherein said at least one second polyamide is present in a proportion by weight of between 0.1% and 20% with respect to total weight of the first and second polyamides in the composition.

2. The composition of claim 1, characterized in that the melting temperature Tf.sub.2 is Tf.sub.130 C.Tf.sub.2Tf.sub.1+10 C.

3-6. (canceled)

7. The composition of claim 1, further comprising reinforcements, advantageously fibers, preferably glass fibers and/or carbon fibers.

8. The composition of claim 7, characterized in that the composition comprises said reinforcements in a proportion by weight of between 0% (excluded) to 70%, advantageously between 15% and 65%, and preferably between 20% and 60%, relative to total weight of the composition.

9. The composition of claim 1, further comprising at least one additive selected from the group consisting of fillers, dyes, stabilizers, plasticizers, impact modifiers, surfactants, nucleating agents, pigments, brighteners, antioxidants, lubricants, flame retardants, natural waxes, and mixtures thereof.

10. The composition of claim 9, characterized in that the composition comprises the nucleating agent or agents in a proportion by weight of between 0% (excluded) to 5%, and advantageously between 0.3% and 4%, relative to total weight of the composition.

11. The composition of claim 9, characterized in that the composition comprises the flame retardant or retardants in a proportion by weight of between 0% (excluded) to 35%, advantageously between 10% and 30%, and preferably between 15% and 25%, relative to total weight of the composition.

12. A monolayer structure or at least one layer of a multilayer structure, comprising the composition of claim 1.

13. The structure of claim 12, characterized in that a form of the structure is a fiber, a film, a tube, a hollow body or an injection molding.

14. An article obtained from the composition of claim 1.

15. A method of shaping the article of claim 14, comprising a step of injection molding.

16. An automotive, construction, household, electrical, electronics, medical or sports product, comprising the article of claim 14.

Description

[0052] In the example to be described hereinbelow, it has even been found that a composition according to the invention crystallized much more effectively in the presence of the second polyamide as defined in the context of the present invention than did a similar composition in which the second polyamide is a crystalline polyamide (PA6.10) having a melting temperature of 220 C., in other words greater by more than 20 C. relative to the melting temperature of approximately 193 C. of MXD.10.

[0053] In one advantageous version of the invention, this second polyamide is selected from PA11, PA12, PA10.10, and PA10.12.

[0054] It is of course possible to contemplate the use of two, or more, second polyamides each having a melting temperature Tf.sub.2 such that Tf.sub.140 C.Tf.sub.2<Tf.sub.1+20 C., where Tf.sub.1 is the melting temperature of the first polyamide MXD.10 or MXD.10/Z.

[0055] With more particular preference the second polyamide is PA11.

[0056] The composition according to the invention comprises said at least second polyamide in a proportion by weight of between 0.1% to 20%, and advantageously between 1% to 10%, relative to the total weight of the first and second polyamides.

[0057] The first and/or second polyamides of the composition may be wholly or partly biobasedthat is, may comprise organic carbon obtained from biomass and determined in accordance with standard ASTF D6866. In such a case, the composition according to the invention may be considered to be itself partly biobased, this having an advantage relative to compositions based on polyamide(s) obtained from fossil raw materials.

[0058] In particular, the sebacic acid of the unit MXD.10 and/or the unit Z may be biobased. Similarly, the second polyamide may be biobased, as in the specific case in which the second polyamide is PA11, a polyamide originating from castor oil.

[0059] According to one advantageous version of the invention, the composition may further comprise reinforcements.

[0060] The addition of reinforcements to the composition of the invention makes it possible to reinforce some of the mechanical properties, particularly the modulus, of the material obtained from this composition. The nature and amount of reinforcements are adapted to the target value for the modulus, which may thus attain values which are very markedly more than 3 GPa, being, for example, of the order of 20 GPa in the case of glass fibers.

[0061] By reinforcements are meant beads, long or short fibers, woven or non-woven continuous fibers, a woven or non-woven mat, or else ground materials, flours, which allow the modulus to be increased when they are combined with polymeric matrices.

[0062] The reinforcements may be selected, for example, from glass beads, fibers, which may be glass fibers, carbon fibers, polymeric fibers, natural fibers (for example, vegetable or animal fibers), and mixtures thereof.

[0063] Advantageously it will be possible for the reinforcements to be biobased, in other words to comprise organic carbon obtained from biomass and determined in accordance with standard ASTF D6866.

[0064] The biobased reinforcements which may be used in the context of the present invention are as follows: [0065] plant fibers, comprising fibers originating from the seminal hairs of seeds (cotton, kapok), bast fibers extracted from plant stems (flax, hemp, jute, ramie, etc), hard fibers extracted from leaves (sisal, abaca, etc.), from trunks (Manilla hemp, wood in general), from husks of fruits (coconut, etc.), [0066] animal fibers which originate from hairs, such as animal fleece, and secretions such as silk, [0067] carbon fibers or carbon nanotubes obtained from biobased raw materials, [0068] polymeric fibers obtained from biobased raw materials, [0069] ground materials from barks, peels or pips (hazelnuts, nuts, etc.), from animal carapaces (crabs, etc.), from grains (rice, etc.).

[0070] It is pointed out that the conversion temperature of the composition according to the invention allows a greater selection of reinforcements, of certain plant fibers, for example, and that this is of real economic and technical advantage, particularly because the material or article obtained from a composition comprising such plant fibers has the advantage of being lighter than that obtained from a composition comprising certain other reinforcements, owing to the lower density of these plant fibers by comparison with that of these other reinforcements.

[0071] In one particular variant of the invention, the reinforcements are advantageously fibers, preferably glass fibers and/or carbon fibers.

[0072] The proportion by weight of said reinforcements is preferably between 0% to 70%, advantageously between 15% and 65%, and more preferably between 20% and 60%, relative to the total weight of the composition according to the invention.

[0073] According to another advantageous version of the invention, the composition may further comprise at least one additive commonly used in polyamide-based compositions.

[0074] The selection of such additives is wider than for the compositions based on PPA or MXD.6, owing to the lowering of the conversion temperature of the composition according to the invention.

[0075] Advantageously, it will be possible for the additive or additives to be biobased, in other words to comprise organic carbon obtained from biomass and determined in accordance with the standard ASTF D6866.

[0076] The amount and nature of this or these additive(s) which may be introduced into the compositions of the invention will be dependent, of course, on the desired effect or effects.

[0077] Without limitation, mention may be made of at least one additive selected from fillers, dyes, stabilizers, especially UV stabilizers, plasticizers, impact modifiers, surfactants, nucleating agents, pigments, brighteners, antioxidants, lubricants, flame retardants, natural waxes, and mixtures thereof.

[0078] The fillers include silica, kaolin, magnesia, slags and/or titanium oxide.

[0079] Mention may also be made of conductive fillers such as carbon black, graphite or else carbon nanotubes. Fillers of this kind allow the composition of the invention, and therefore the material to be obtained from said composition, to be endowed with antistatic properties.

[0080] The additives also include nucleating agents known to the skilled person, such as talc, for example. Although not indispensable for allowing crystallization of the composition according to the invention, they may nevertheless be introduced into said composition.

[0081] Advantageously, the proportion by weight of said nucleating agent or agents is between 0% to 5%, and advantageously between 0.3% and 4%, relative to the total weight of the composition according to the invention.

[0082] The composition may further comprise one or more flame retardants such as, for example, Mg(OH).sub.2, melamine pyrophosphates, melamine cyanurates, ammonium polyphosphates, metal salts of phosphinic acid or diphosphinic acid, or else polymers containing at least one metal salt of phosphinic acid or diphosphinic acid.

[0083] The salt may be selected, for example, from aluminum methylethylphosphinate and aluminum diethylphosphinate. Mixtures containing such metal salts are sold by Clariant under the trade name Exolit OP1311, OP1312, OP1230 and OP1314.

[0084] It is specified that the conversion temperature of the composition according to the invention allows a wider selection of flame retardants, and this is of real economic and technical advantage.

[0085] The proportion by weight of the flame retardant or retardants is preferably between 0% and 35%, advantageously between 10% and 30%, and preferably between 15% and 25%, relative to the total weight of the composition according to the invention.

[0086] A composition which is advantageous in the sense of the invention may comprise the following proportions by weight of the various compounds below: [0087] from 10% to 100% of a first polyamide MXD.10/Z, preferably of MXD.10, and of a second polyamide, preferably PA11, the proportion by weight of the second polyamide representing from 0.1% to 20% of the first and second polyamides, [0088] from 0% to 70% of carbon and/or glass fibers, [0089] from 0% to 5% of a nucleating agent, such as talc, [0090] from 0% to 35% of a flame retardant.

[0091] The composition according to the invention may be used to produce a structure.

[0092] This structure may be a monolayer structure, when formed only of the composition according to the invention.

[0093] This structure may also be a multilayer structure, when it comprises at least two layers and when at least one of the different layers forming the structure is formed of the composition according to the invention.

[0094] The structure, whether monolayer or multilayer, may take the form in particular of fibers, a film, a tube, a hollow body or an injection molding. The invention is particularly appropriate to the production of an item or article obtained by an injection molding process.

[0095] The invention likewise provides a process for preparing a composition of the invention as defined above.

[0096] According to the invention, the composition may be prepared by any method which allows homogeneous mixing of the polymers and any additives and/or other reinforcements forming part of the composition according to the invention.

[0097] These methods include, in particular, extrusion in the melt state, compacting or else roll milling.

[0098] More particularly, the composition according to the invention is prepared by mixing in the melt state of all of the polymers and any additives and fibers, and is then converted, in the form of granules, for example, by compounding on an apparatus known to the skilled person, such as a twin-screw extruder, a co-grinder or a mixer.

[0099] The composition according to the invention, obtained by the preparation process described above, may be subsequently converted for use or a subsequent transformation as known to the skilled person, particularly by means of devices such as an injection press or an extruder.

[0100] The composition according to the invention may also be introduced into a twin-screw extruder which, in the absence of an intermediate pelletizing step, supplies an injection press or an extruder in accordance with an implementation device known to the skilled person.

[0101] The invention is directed in particular to a method of shaping an article obtained from the composition as defined above, said method comprising a step of injection molding.

[0102] An article of this kind may be obtained by injection, by extrusion, by co-extrusion or by multiple injection, starting from at least one composition as defined above.

[0103] The invention provides, lastly, an article obtained from the composition of the invention, and also the use of said article.

[0104] Such an article may advantageously be used in the automotive or construction fields or in the household, electrical, electronics, medical or sports segments.

[0105] Given that the composition according to the invention has a lower density than compositions based on PPA or MXD.6, an article obtained from such a composition is lighter for the same volume.

[0106] The composition according to the invention may advantageously be contemplated for the production of all or part of elements of electrical and electronic goods, such as encapsulated solenoids, pumps, telephones, computers, printers, photocopiers, modems, monitors, remote control units, cameras, circuit breakers, sheaths of electrical cables, optical fibers, switches, and multimedia systems. These elements of electrical and electronic goods cover not only the structural parts of such goods (casings, housings, etc.) but also their possible associated accessories (earpieces, connecting elements, cables, etc.).

[0107] The composition may also be used for producing all or part of automotive equipment such as tube connectors, pumps, underhood injection moldings, injection moldings in the form of bumpers, floorboards, and door trim.

[0108] The composition may also be used for producing all or parts of medical or surgical equipment, of packaging or else of sports or leisure articles, such as cycle equipment (saddle, pedals), or to form rigid elements of footwear, for example.

[0109] The composition may further be used for producing all or part of elements of household equipment (air conditioner) or kitchen electricals (coffee maker, oven, washing machine, dishwasher).

[0110] The present invention will now be described in the examples below, such examples being given solely by way of illustration, and obviously without limitation.

Third Part

[0111] Preparation of Compositions 1.1 to 1.5, 2.1 to 2.6, and 3

[0112] The compositions were prepared from the following products: [0113] PA MXD.10: homopolyamide obtained by polycondensation of 1,3-xylylenediamine and decanedioic acid (sebacic acid), comprising 57% of biobased carbon (Arkema) and having a melting temperature of 193 C. [0114] PA 11: homopolyamide obtained by polycondensation of 11-aminoundecanedioic acid, containing 100% of biobased carbon (Arkema) and having a melting temperature of 185 C. [0115] PA 6.10: homopolyamide obtained by polycondensation of hexanediamine and decanedioic acid (Arkema) and having a melting temperature of 220 C. [0116] Steamic OOS DG Talc: nucleating agent (Luzenac) [0117] Glass fibers: reinforcement sold as CT FT 692 (ASAHI) [0118] Irganox 1010: antioxidant (CIBA) [0119] Calcium stearate and Wax E: lubricant/mold release agent (BASF and CECA, respectively)

[0120] In a first part of the study, compositions containing no glass fibers are prepared by mixing the various constituents (compounding) using a Haake co-rotating twin-screw extruder, at a setpoint temperature of 260 C.

[0121] The various constituents of these compositions, in the respective proportions by weight as reported in table 1, are introduced via the feed hopper in the 1st barrel.

TABLE-US-00001 TABLE 1 Composition 1.1 1.2 1.3 1.4 1.5 comp. comp. comp. inv. inv. PA MXD.10 100 89.6 98.6 89.6 88.6 PA 6.10 10 Talc 1 1 PA 11 10 10 IRGANOX 1010 0.4 0.4 0.4 0.4

[0122] Compositions 1.1, 1.2, and 1.3 are comparative (comp.) compositions, whereas compositions 1.4 and 1.5 are compositions in accordance with the invention (inv.). In particular, composition 1.2 comp. is in accordance with the composition taught by document EP 0 272 503 A1.

[0123] In a second part of the study, compositions containing glass fibers are prepared by mixing the various constituents (compounding) using an MC26 co-rotating twin-screw extruder, at a setpoint temperature of 260 C.

[0124] The various constituents of these compositions, in the respective proportions by weight as reported in table 2, are introduced via the feed hopper at the 1st barrel, with the exception of the glass fibers, which are introduced in a side feed.

TABLE-US-00002 TABLE 2 Composition 2.1 2.2 2.3 2.4 2.5 2.6 comp. comp. comp. inv. comp. inv. PA MXD.10 49.4 49 44.08 44.08 43.59 43.59 PA 6.10 4.92 4.92 Talc 0.49 0.49 PA 11 4.92 4.92 Glass fibers 50 50 50 50 50 50 Wax E 0.3 0.3 0.3 0.3 0.3 0.3 Calcium stearate 0.3 0.3 0.3 0.3 0.3 0.3 Irganox 1010 0.4 0.4 0.4 0.4 0.4

[0125] Compositions 2.1 to 2.3 and 2.5 are comparative (comp.) compositions, whereas compositions 2.4 and 2.6 are compositions in accordance with the invention (inv.). In particular, composition 2.3 comp. is in accordance with a composition taught by document EP 0 272 503 A1.

[0126] In a third part of the study, a composition 3 in accordance with the invention and containing glass fibers is prepared by mixing (compounding) using a Werner 40 co-rotating twin-screw extruder, at a conversion temperature of 260 C.

[0127] The various constituents of this composition, in the respective proportions by weight as reported in table 3, are introduced via the feed hopper at the 1st barrel, with the exception of the glass fibers, which are introduced as a side feed.

[0128] It will be noted that the various constituents of composition 3 are the same as those of composition 2.6 featuring in table 2.

TABLE-US-00003 TABLE 3 Composition 3 inv. PA MXD.10 43.59 PA 11 4.92 Glass fibers 50 Irganox 1010 0.4 Wax E 0.3 Calcium stearate 0.3 Steamic OOS DG talc 0.49

[0129] Injection of Compositions 1.1 to 1.5, 2.1 to 2.6, and 3

[0130] With the exception of the mold temperature, which is variable, the various compositions 1.1 to 1.5, 2.1 to 2.6, and 3 are subsequently injected under the following conditions: [0131] die feed temperature: 240/260 C. [0132] mold temperature: 35 C. or 90 C. or 130 C. [0133] Flow rate: 27 cm.sup.3/s [0134] Cycle time: 60 s (corresponding to a hold time of 20 s and a cooling time of 40 s)

[0135] Characterization of the Materials

[0136] A Study of the Crystallization of Compositions 1.1 to 1.5 by DSC Analysis:

[0137] 80104 mm.sup.3 bars are prepared from compositions 1.1 to 1.5 by injection in a mold at 90 C. with water as heat-transfer fluid. A sample is taken of these bars for DSC analysis. The analytical protocol used is as follows:

[0138] temperature equilibration at 20 C.,

[0139] 1st heating to 280 C. at a heating rate of 20 C./min.

[0140] During the 1st heating, the energy supplied to the system causes crystallization of the part of the composition that has not crystallized during the conversion step, in this case injection. The enthalpy of crystallization measured at this point (J/g) allows the phenomenon to be quantified.

[0141] Subsequently, at the melting temperature, the composition is melted-specifically, the part of the composition which crystallized during the injection step and the part of the composition which crystallized during the 1st heating are melted. The enthalpy of fusion measured at this point (J/g) allows the phenomenon to be quantified.

[0142] The enthalpy of crystallization (measured during the 1st heating of the DSC analysis)/enthalpy of fusion (measured during the 1st heating of the DSC analysis) ratio allows quantification of the capacity of the system to crystallize readily during the step of conversion by injection.

[0143] The lower this ratio, the more readily the system crystallizes during the conversion step, this being the desired objective in the context of the present invention.

[0144] The results of the DSC analyses are reported in table 4 below.

TABLE-US-00004 TABLE 4 Composition 1.1 1.2 1.3 1.4 1.5 comp. comp. comp. inv. inv. Enthalpy of crystallization 35.3 33.8 21.8 11.3 8.3 (J/g) Enthalpy of fusion (J/g) 39.2 39.0 40.5 41.9 40.8 Enthalpy of crystallization/ 0.90 0.87 0.54 0.27 0.20 enthalpy of fusion ratio

[0145] It is seen that compositions 1.4 and 1.5 according to the invention have an enthalpy of crystallization/enthalpy of fusion ratio which is lower than that of comparative compositions 1.1, 1.2, and 1.3. This means that compositions 1.4 and 1.5 according to the invention crystallize more readily than the comparative compositions 1.1, 1.2., and 1.3 during the step of conversion by injection.

[0146] More particularly, comparing the ratios obtained for compositions 1.2 and 1.4, it is observed that PA11, which has a melting temperature of 185 C., has a greater nucleating power than PA6.10 with a melting temperature of 220 C. This observation goes against the teaching of document EP 0 275 503 A1, which advised introducing a crystalline polyamide having a melting temperature at least 20 C. greater than that of MXD.10.

[0147] Comparing, moreover, the ratios obtained for compositions 1.3 and 1.4, it is observed that PA11 also has a greater nucleating power than talc. It will be noted, lastly, that composition 1.5, comprising both PA11 and talc, gives the best value for enthalpy of crystallization/enthalpy of fusion ratio.

[0148] B Study of the Crystallization of Compositions 2.1 to 2.6 by DSC Analysis:

[0149] Tensile test specimens 2 mm in thickness were injection-molded from compositions 2.1 to 2.6 in accordance with the protocol of standard ISO 527 1 BA, in a mold at 95 C., the cycle time, the time allowing said test specimens to be obtained, being 15 s.

[0150] Samples were then taken for DSC analysis. The analytical protocol used is the same as that described above for the DSC analysis of the bars formed from compositions 1.1 to 1.5.

[0151] The results of the DSC analyses are reported in table 5 below.

TABLE-US-00005 TABLE 5 Composition 2.1 2.2 2.3 2.4 2.5 2.6 comp. comp. comp. inv. comp. inv. Enthalpy of 16.4 17.8 13.4 7.6 9.0 4.3 crystallization (J/g) Enthalpy of 25.6 24.7 25 23.5 24.6 21.8 fusion (J/g) Enthalpy of 0.64 0.72 0.54 0.32 0.37 0.20 crystallization/ enthalpy of fusion ratio

[0152] Here again it is found that compositions 2.4 and 2.6 according to the invention have an enthalpy of crystallization/enthalpy of fusion ratio [0153] which is lower than comparative compositions 2.1 and 2.2, which do not contain a second polyamide, and [0154] which is also lower than the respective comparative compositions 2.3 and 2.5, which comprise PA6.10 as second polyamide, and, where appropriate, talc.

[0155] Compositions 2.4 and 2.6 according to the invention crystallize more readily than comparative compositions 2.1, 2.2, 2.3, and 2.5 during the injection molding step.

[0156] Comparing the ratios obtained for compositions 2.3 and 2.4, it is noted that the nucleating power of PA11 still remains much higher than that of PA6.10, even in the presence of glass fibers.

[0157] This observation remains true even when talc is added as a nucleating agent to the compositions; indeed, the ratio obtained for composition 2.6 according to the invention is lower than that for comparative composition 2.5.

[0158] It will be noted, lastly, that composition 2.6, comprising both PA11 and talc, gives the best enthalpy of crystallization/enthalpy of fusion ratio value.

[0159] C Study of Mechanical Properties on Composition 3:

[0160] Tensile Modulus:

[0161] Tensile test specimens 4 mm in thickness are prepared from composition 3 by injection in a mold at different temperatures (35 C., 90 C., and 130 C.), in accordance with the protocol of standard ISO 527 1A, the cycle timethe time allowing said test specimens to be obtainedbeing 40 s.

[0162] These test specimens are tested dry without conditioning or else are conditioned for 15 days in a controlled aTfosphere (at 23 C. and 50% relative humidity).

[0163] These test specimens are evaluated in accordance with said standard ISO 527. Accordingly, the tensile modulus is measured (GPa).

[0164] Charpy Impact:

[0165] 80104 mm.sup.3 bars are prepared from composition 3 by injection in a mold at different temperatures (35 C., 90 C., and 130 C.).

[0166] These bars are evaluated dry without conditioning or else are conditioned for 15 days in a controlled aTfosphere (at 23 and 50% relative humidity).

[0167] They are tested in the Charpy pendulum impact test in accordance with standard ISO 179-1eU, with a pendulum of 7.5 joules. Hence a measurement is made of the energy absorbed by the bars, expressed in kJ/m.sup.2.

[0168] Reported in tables 6 and 7 below are the results of the measurements of tensile modulus and Charpy impact, as a function of the injection-mold temperature. Table 6 reports measurements made on the test specimens and bars tested under dry conditions, without conditioning. Table 7 reports measurements made on test specimens and bars tested after conditioning for 15 days in a controlled atmosphere (at 23 C. and 50% relative humidity).

TABLE-US-00006 TABLE 6 Composition 3 Temperature of injection mold 35 C. 90 C. 130 C. Tensile modulus (GPa) dry 20 22 22 Notched Charpy impact dry 10 10 9.5 at 23 C. (kJ/m.sup.2)

TABLE-US-00007 TABLE 7 Composition 3 Temperature of injection mold 35 C. 90 C. 130 C. Tensile modulus (GPa) conditioned 20 22 22 Notched Charpy impact at conditioned 10 10 9.5 23 C. (kJ/m.sup.2)

[0169] It is noted that composition 3 according to the invention possesses mechanical properties which are similar and optimum, irrespective of the temperature of the injection mold used and the conditioning.

[0170] The compositions of the invention therefore offer the advantage of being able to use molds regulated either by oil or by water.