Polyamide Composition

Abstract

The present invention primarily relates to a composition comprising 20 to 70 wt. % of a polyamide component comprising an aliphatic semi-crystalline polyamide having an average of at least 7 carbon atoms per nitrogen atom; 30 to 80 wt. % of glass fibers; and 0 to 10 wt. % of additives, the sum of components (a), (b) and (c) adding up to 100%, characterized in that the aliphatic semi-crystalline polyamide has a total acidity of 70 to 180, preferably 100 to 150 μeq / g, as measured by potentiometric titration.

Description

[Technical field]

[0001] This patent application relates to reinforced semi-crystalline aliphatic polyamide compositions having improved dimensional stability and robust mechanical properties in the presence of moisture.

[0002] The invention also relates to a process for its production, to the articles obtained therefrom and to the use of the semicrystalline aliphatic polyamide for producing articles having improved dimensional stability and improved mechanical properties, in particular improved in terms of modulus of elasticity.

[0003] Very high stiffness polyamide compounds are required in the electrical and electronics sector, for example for the manufacture of phone cases or computer chassis. Such compounds may also be advantageous for reducing the weight of electronic devices, since they allow a reduction in the thickness of the components. A common route to obtain high stiffness polyamides is to add reinforcing materials such as glass fibers to form semi-crystalline aliphatic polyamide compounds.

[0004] The mechanical properties of such blends depend firstly on the mechanical properties of the polymer and the glass fibre, and secondly on the ability of the polymer to transmit stress to the fibre-polymer interface. Moisture (humidity) is one of the main external factors that can affect this interface and thus negatively affect the mechanical properties, especially the modulus.

[0005] Given their affinity for water, polyamides, especially semi-crystalline aliphatic polyamides, are particularly susceptible to moisture sorption. The absorbed water has a plasticizing effect on the polyamide, which has several effects on its properties, in particular: - causes expansion that adversely affects the dimensional stability of the part; and - It can reduce the modulus of the material, especially at room temperature.

[0006] Therefore, one way to improve the properties of polyamide compounds, especially their dimensional stability, and to obtain more robust mechanical properties, especially with regard to modulus, is to reduce their moisture sorption.

[0007] Thus, patent FR3043681B1 states that the addition of a semi-crystalline polyamide containing 8 or more carbon atoms per nitrogen atom to an amorphous polyamide compound can improve its dimensional stability by reducing the water absorption at 23°C and 50% RH relative to the expected value calculated from the weighted absorption rates of its components.

[0008] In the case of polyamide compounds reinforced with fillers such as glass fibers, absorbed water can further alter the interactions between the polyamide and the filler.

[0009] Patent application US2017 / 0029621A1 teaches that the use of polyamides with specific chain end groups can limit the increase in molecular weight during injection molding at high temperatures. This document does not mention the issues related to moisture sorption of polyamides, nor does it address polyamides reinforced with fillers. Summary of the Invention

[0010] It is therefore an object of the present invention to provide a semi-crystalline aliphatic polyamide composition reinforced with a filler such as glass fibre, which is robust to moisture and has improved dimensional stability and mechanical properties, in particular in terms of modulus of elasticity.

[0011] Indeed, the present invention is primarily based on the surprising observation that it is possible to limit the moisture sorption of semi-crystalline aliphatic polyamide compositions by adjusting the nature and content of the amine and carboxyl groups at the chain ends. In fact, lower moisture sorption leads to improved dimensional stability as well as improved stability of mechanical properties in humid environments.

[0012] Thus, according to a first aspect, one subject of the invention is a method for producing a medicament for use in a pharmaceutical composition comprising: (a) 20% to 70% by weight of a polyamide component comprising an aliphatic semicrystalline polyamide having an average of at least 7 carbon atoms per nitrogen atom; (b) 30% to 80% by weight glass fibers; and (c) 0 to 10% by weight of additives wherein the sum of components (a), (b) and (c) is 100%, The composition is characterized in that the semi-crystalline aliphatic polyamide has a total acidity, as measured by potentiometric titration, of 70 to 180 μeq / g, preferably 100 to 150 μeq / g.

[0013] Advantageously, the semi-crystalline aliphatic polyamide has a total basicity, measured by potentiometric titration, between 10 and 100 μeq / g.

[0014] Preference is given to aliphatic semicrystalline polyamides of the XY type obtained by polycondensation of at least one diamine, in particular a linear or branched aliphatic diamine having from 5 to 12 carbon atoms, with at least one dicarboxylic acid, in particular a linear or branched aliphatic dicarboxylic acid having from 9 to 18 carbon atoms.

[0015] Alternatively, the aliphatic semicrystalline polyamide may be a polyamide of Z type obtained by polycondensation of at least one aminocarboxylic acid and / or at least one lactam, which may advantageously contain 11 or 12 carbon atoms.

[0016] The aliphatic semicrystalline polyamide may in particular be selected from the group consisting of PA59, PA510, PA69, PA512, PA612, PA109, PA610, PA1010, PA1012, PA11, PA12 and PA1212.

[0017] The glass fibres may in particular be glass fibres of circular or non-circular cross section.

[0018] According to one embodiment, the composition comprises 30% to 65% by weight of glass fibers.

[0019] Advantageously, the semicrystalline polyamide has an intrinsic viscosity ranging from 0.85 to 1.30 dl / g, measured according to the ISO 307:2007 standard but in a 0.5% by weight m-cresol solution at 20°C.

[0020] According to a second aspect, the invention relates to an article obtained from said composition, in particular by injection molding.

[0021] According to a third aspect, the present invention provides a method for producing ... composition comprising the steps of: (i) a) 20% to 70% by weight of a polyamide component comprising an aliphatic semicrystalline polyamide having an average of at least 7 carbon atoms per nitrogen atom and having a total acidity, as measured by potentiometric titration, between 70 and 180 μeq / g; b) 30% to 80% by weight glass fibers; and c) 0 to 10% by weight of additives wherein the sum of components (a), (b) and (c) is 100%; and (ii) optionally shaping the mixture obtained in step (i); The present invention relates to a method for producing said composition, comprising the steps of:

[0022] Finally, according to a fourth aspect, the invention relates to the use of an aliphatic semicrystalline polyamide having an average of at least 7 carbon atoms per nitrogen and a total acidity, measured by potentiometric titration, between 70 and 180 μeq / g, for the preparation of a composition with low water sorption, in particular as a matrix of the compositions described above. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] [Terminology definition] The term "polyamide" is understood to mean a compound containing at least two identical or different repeating units formed by polycondensation of dicarboxylic acids and diamines, diisocyanates and dicarboxylic acids, amino acids, lactams, or mixtures thereof.

[0024] The nomenclature used to define polyamides is described in the ISO16396-1:2015 standard "Plastics - Polyamide (PA) moulding and extrusion materials - Part 1: Basis for designation systems, product marking and specification designation". When polyamides are derived from the polycondensation of carboxylic diacids and diamines, they are represented as (Ca diamine)·(Cb diacid), where a represents the number of carbon atoms in the diamine and b represents the number of carbon atoms in the diacid. Polyamides derived from the condensation of two different monomers are called polyamides of the X·Y type, while polyamides derived from the condensation of a single monomer such as a lactam or amino carboxylic acid are called polyamides of the Z type.

[0025] The polyamide may be a homopolyamide, consisting of identical repeating units, or a copolyamide, comprising several different repeating units. Advantageously, when the polyamide is a copolyamide, it is derived from a monomer mixture consisting of a main monomer and up to 10% by weight, advantageously up to 5% by weight, of additional monomers.

[0026] The term "semicrystalline polyamide" is understood to mean a polyamide having a melting temperature (Tm) in DSC, measured according to the ISO 11357-3 standard of 2011, and a crystallization enthalpy during a cooling step in DSC at a rate of 20 K / min, greater than 30 J / g, preferably greater than 40 J / g, measured according to the ISO 11357-3 standard of 2013.

[0027] The term "aliphatic polyamide" is understood to mean a polyamide resulting from the polycondensation of aliphatic monomers, which are preferably acyclic and more particularly linear.

[0028] The term "viscosity" is understood to mean the intrinsic viscosity, measured according to the ISO 307:2007 standard, but in a 0.5% by weight m-cresol solution at 20° C. using a viscometer equipped with a Micro-Ubbelohde viscometer tube. The intrinsic viscosity is calculated by the following formula: 1 / c * ln(ts / t0), where c: concentration of the solution ts: solution flow time t0: Flow time of solvent only

[0029] The term "melting temperature" is understood to mean the temperature at which an at least partially crystalline polymer passes into a viscous liquid state, measured by differential scanning calorimetry (DSC) according to the NF EN ISO 11357-3 standard at a heating rate of 20°C / min.

[0030] The term "total acidity" of a polyamide is understood to mean the total content of acid functions, in particular acid chain ends, in particular of the formula --COOH, measured by potentiometric titration according to the protocol described below.

[0031] The term "total basicity" of a polyamide is understood to mean the total content of basic functions, in particular basic chain ends, in particular of formula -NH2, measured by potentiometric titration according to the protocol described below.

[0032] According to the present invention, the composition targeted in this application is (a) 20% to 70% by weight of a polyamide component comprising an aliphatic semicrystalline polyamide having an average of at least 7 carbon atoms per nitrogen atom; (b) 30% to 80% by weight glass fibers; and (c) 0 to 10% by weight of additives The sum of components (a), (b) and (c) is 100%, The semi-crystalline aliphatic polyamide is characterized in that it has a total acidity, measured by potentiometric titration, of 70 to 180 μeq / g, preferably 100 to 150 μeq / g.

[0033] In fact, the present invention is primarily based on the surprising observation that it is possible to limit the moisture sorption of semi-crystalline aliphatic polyamide compositions by adjusting the acidity of the polyamide, and in particular the nature and content of the functional groups at the chain ends. In fact, lower moisture sorption leads to improved dimensional stability and also to improved stability of mechanical properties in humid environments.

[0034] Moreover, it was found that in such compositions filled with glass fibres, the mechanical properties were more favourable when the phosphoric acid content of the semi-crystalline aliphatic polyamide was limited, and, without wishing to be bound by this assumption, it is believed at this stage that this effect is due to unfavourable interactions with the glass fibres.

[0035] [Semi-crystalline polyamide] The semi-crystalline aliphatic polyamide, component (a) of the composition of the present invention, is characterized primarily by containing an average of at least 7 carbon atoms per nitrogen atom. As mentioned above, this polyamide may be derived from the polycondensation of dicarboxylic acids and diamines, amino acids, lactams, or mixtures thereof.

[0036] The semi-crystalline aliphatic polyamide is if it is a homopolyamide obtained by polymerization of amino acids or lactams, the number of carbon atoms in said amino acids or lactams is at least equal to 7, advantageously at least equal to 8, preferably 9 or more and in particular 10 or more; or for homopolyamides obtained by polymerization of diacids and diamines and which contain amide units corresponding to the formula (Ca diamine)·(Cb diacid), the sum (a+b) / 2 is greater than or equal to 7, advantageously greater than or equal to 8, preferably greater than or equal to 9 and in particular greater than or equal to 10.

[0037] Thus, PA6.12 is a polyamide containing 9 carbon atoms per nitrogen atom and PA6.13 is a polyamide containing 9.5 carbon atoms.

[0038] The semi-crystalline aliphatic polyamide may be obtained from linear and / or branched monomers. Preferably, it is a polyamide obtained partly or entirely from linear monomers.

[0039] According to a first embodiment, the semicrystalline aliphatic polyamide is a polyamide of Z type obtained by polycondensation of at least one aminocarboxylic acid or of at least one lactam.

[0040] Thus, the semi-crystalline aliphatic polyamide may comprise at least one unit derived from an amino acid chosen from 9-aminononanoic acid, 10-aminodecanoic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid. Advantageously, the polyamide comprises at least one unit derived from 11-aminoundecanoic acid or 12-aminododecanoic acid.

[0041] Alternatively, the semi-crystalline aliphatic polyamide may comprise at least one unit derived from a lactam selected from pyrrolidinone, piperidinone, caprolactam, enantholactam, caprylolactam, pelargolactam, decanolactam, undecanolactam and laurolactam.

[0042] When the semicrystalline aliphatic polyamide is a homopolyamide comprising units derived from lactam, the latter comprises at least 7 carbon atoms and is therefore in particular selected from enantholactam, caprylolactam, pelargolactam, decanolactam, undecanolactam and laurolactam. Advantageously, the polyamide comprises at least one unit derived from undecanolactam or laurolactam.

[0043] Preferably, the semi-crystalline aliphatic polyamide is derived from the polycondensation of monomers containing at least one amino carboxylic acid and / or at least one lactam, containing 11 or 12 carbon atoms.

[0044] Advantageously, the polyamide contains less than 10% by weight, in particular less than 5% by weight and more particularly less than 0.1% by weight of caprolactam-derived units, or no caprolactam-derived units at all.

[0045] According to another embodiment, the semi-crystalline aliphatic polyamide is a polyamide of type XY and comprises at least one unit corresponding to the formula (Ca diamine)·(Cb diacid).

[0046] The Ca diamine may in particular be a linear aliphatic diamine. Similarly, the Cb diacid may in particular be a linear aliphatic diamine.

[0047] Preferentially, when the Ca aliphatic diamine is linear, it is selected from butanediamine (a=4), pentanediamine (a=5), hexanediamine (a=6), heptanediamine (a=7), octanediamine (a=8), nonanediamine (a=9), decanediamine 20 (a=10), undecanediamine (a=11), dodecanediamine (a=12), tridecanediamine (a=13), tetradecanediamine (a=14), hexadecanediamine (a=16), octadecanediamine (a=18), octadecanediamine (a=18), eicosanediamine (a=20), docosanediamine (a=22) and diamines derived from fatty acids.

[0048] Preferably, when the aliphatic diacid is linear, it is selected from succinic acid (b=4), pentanedioic acid (b=5), adipic acid (b=6), heptanedioic acid (b=7), octanedioic acid (b=8), azelaic acid (b=9), sebacic acid (b=10), undecanediic acid (b=11), dodecanediic acid 20 (b=12), brassylic acid (b=13), tetradecanedioic acid (b=14), hexadecanedioic acid (b=16), octadecanediic acid (b=18), octadecenedioic acid (b=18), eicosanedioic acid (b=20), docosanedioic acid (b=22) and fatty acid dimers, in particular those containing 36 carbons.

[0049] The abovementioned fatty acid dimers can be obtained by oligomerization or polymerization of unsaturated monobasic fatty acids with long hydrocarbon chains, such as linoleic acid and oleic acid, as described in particular in document EP 0 471 566.

[0050] However, some or all of the monomers (amino acids, diamines, diacids) used to prepare the semi-crystalline aliphatic polyamides may also be branched. Thus, 2-methyl-1,5-diaminopentane may be used as a branched diamine.

[0051] Advantageously, the aliphatic polyamides of type XY are obtained by polycondensation of at least one linear or branched aliphatic diamine having from 5 to 12 carbon atoms and at least one linear or branched aliphatic dicarboxylic acid having from 9 to 18 carbon atoms.

[0052] Preferably, the monomers used in the preparation of the semi-crystalline aliphatic polyamides are saturated compounds.

[0053] Part of the above-mentioned monomers can be replaced by other monomers. Thus, part of the aliphatic dicarboxylic acids can be replaced by one or more aromatic or cycloaliphatic dicarboxylic acids. Similarly, part of the aliphatic diamines can be replaced by cycloaliphatic and / or aromatic or araliphatic diamines. Preferably, this replacement is carried out in a very limited amount of up to 10% by weight, in particular up to 5% by weight, in particular up to 2.5% by weight of the total monomers.

[0054] The aliphatic semi-crystalline polyamides useful in the polyamide composition may in particular be selected from the group consisting of PA410, PA59, PA510, PA69, PA610, PA512, PA612, PA613, PA614, PA615, PA616, PA618, PA910, PA912, PA913, PA914, PA915, PA916, PA918, PA936, PA109, PA1010, PA1012, PA1013, PA1014, PA11, PA12, PA1210, PA1212, PA1213, PA1214, and copolymers and mixtures thereof.

[0055] Particularly preferred are the aliphatic semicrystalline polyamides PA59, PA510, PA69, PA610, PA512, PA612, PA109, PA1010, PA1012, PA11, PA12 and PA1212, and copolymers and mixtures thereof.

[0056] Advantageously, the polyamide composition does not contain short-chain semi-crystalline polyamides, such as in particular PA6 and PA66, since these polyamides absorb moisture very highly and therefore are unable to achieve the dimensional stability required for the intended application.

[0057] The composition according to the invention may comprise one, two or more different semi-crystalline polyamides. Preferably, the composition comprises one or two different semi-crystalline polyamides.

[0058] The semi-crystalline aliphatic polyamide, component (a), is characterized by having a total acidity, measured by potentiometric titration, between 70 and 180 μeq / g, preferably between 100 and 150 μeq / g.

[0059] According to certain embodiments, the total acidity of the aliphatic semi-crystalline polyamide in the composition is from 70 to 75 μeq / g; or from 75 to 80 μeq / g; or from 80 to 85 μeq / g; or from 85 to 90 μeq / g; or from 90 to 95 μeq / g; or from 95 to 100 μeq / g; or from 100 to 105 μeq / g; or from 105 to 110 μeq / g; or from 110 to 115 μeq / g; or from 115 to 120 μeq / g; or from 120 to 125 μeq / g; or from 125 to 130 μeq / g; or from 130 to 135 μeq / g; or from 135 to 140 μeq / g, or from 145 to 150 μeq / g; or from 150 to 155 μeq / g; or from 155 to 160 μeq / g; or from 160 to 165 μeq / g; or from 165 to 170 μeq / g; or from 170 to 175 μeq / g; or from 175 to 180 μeq / g.

[0060] The total acidity of a semicrystalline polyamide reflects the content of carboxyl groups, especially at the chain ends.

[0061] Polyamides may contain residues of mineral acids, especially phosphoric acid, used as catalysts during their synthesis. These catalysts may contribute to the acidity of the polyamide. Nevertheless, they do not produce the positive effects reported in this application.

[0062] Thus, the aliphatic semicrystalline polyamide is advantageously prepared according to the protocol described below. 31 It has a phosphoric acid content, determined by NMR, of not more than 8000 ppm, advantageously not more than 7000 ppm, in particular not more than 6000 ppm, more in particular not more than 5000 ppm.

[0063] Advantageously, the aliphatic semicrystalline polyamide further has a total basicity, measured by potentiometric titration, of less than 100, in particular from 10 to 100 μeq / g, preferably less than 80, in particular less than 60 μeq / g, in particular less than 40 μeq / g, more in particular from 10 to 30 μeq / g.

[0064] According to certain embodiments, the basicity of the aliphatic semi-crystalline polyamide may vary from 10 to 15 μeq / g; or from 15 to 20 μeq / g; or from 20 to 25 μeq / g; or from 25 to 30 μeq / g; or from 30 to 35 μeq / g; or from 35 to 40 μeq / g; or from 40 to 45 μeq / g; or from 45 to 50 μeq / g; or from 50 to 55 μeq / g; or from 55 to 60 μeq / g; or from 60 to 65 μeq / g; or from 65 to 70 μeq / g; or from 70 to 75 μeq / g; or from 75 to μeq / g; or from 85 to 90 μeq / g; or from 90 to 95 μeq / g; or from 95 to 100 μeq / g.

[0065] The total basicity of a semicrystalline polyamide reflects the content of carboxyl groups neutralized by strong bases such as KOH, particularly amine groups and chain ends.

[0066] The total basicity and total acidity of the polyamide can be controlled by adding a chain limiter during synthesis.

[0067] Advantageously, the polyamide according to the invention is limited by linear aliphatic C2-C18 monocarboxylic acids, linear aliphatic C4-C18 monoamines, linear aliphatic C3-C36 dicarboxylic acids and / or linear aliphatic C4-C18 diamines.

[0068] The acid used as the chain limiter may be selected from acetic acid, propionic acid, lactic acid, valeric acid, caproic acid, capric acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, isobutyric acid, succinic acid, pentanedioic acid, adipic acid, heptanedioic acid, octanedioic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, octadecenedioic acid, eicosane diacid, and docosane diacid.

[0069] Preferably, the polyamide is limited by linear aliphatic C6-C12 monocarboxylic acids and / or linear aliphatic C6-C12 dicarboxylic acids, particularly preferably linear aliphatic C6-C12 dicarboxylic acids. Preferred acids are adipic acid, sebacic acid and lauric acid.

[0070] The amines used as chain limiters may be selected from butylamine, hexylamine, octylamine, decylamine, laurylamine, stearylamine, diethylamine, dipropylamine, dibutylamine, hexanediamine, heptanediamine, octanediamine, nonanediamine, decanediamine, undecanediamine, dodecanediamine.

[0071] Preferably, the polyamide according to the invention is limited by C6-C12 monoamines and / or C6-C12 diamines. Preferably, decane diamine and laurylamine are used.

[0072] As mentioned above, the total basicity of the polyamide can also be increased by neutralizing the carboxyl groups at the chain ends with a strong base such as KOH.

[0073] Advantageously, the semicrystalline polyamide further has an intrinsic viscosity, measured according to the ISO 307:2007 standard, of between 0.85 and 1.30 dl / g, preferably between 0.90 and 1.1 dl / g.

[0074] According to certain embodiments, the intrinsic viscosity of the aliphatic semi-crystalline polyamide in the composition may vary from 0.85 to 0.90 dl / g, or from 0.90 to 0.95 dl / g, or from 0.95 to 1.0 dl / g, or from 1.1 dl / g to 1.15 dl / g, or from 1.15 to 1.2 dl / g, or from 1.2 to 1.25 dl / g, or from 1.25 to 1.3 dl / g.

[0075] According to the invention, the aliphatic semicrystalline polyamide represents from 20% to 70% by weight of the composition.

[0076] According to certain embodiments, the content of aliphatic semicrystalline polyamide in the composition may vary from 20% to 25% by weight; or from 25% to 30% by weight, or from 30% to 35% by weight, or from 35% to 40% by weight, or from 45% to 50% by weight, or from 50% to 55% by weight, or from 55% to 60% by weight, or from 60% to 65% by weight, or from 65% to 70% by weight.

[0077] [Glass fiber] The composition according to the invention further comprises glass fibres as a reinforcing material.

[0078] For the purposes of the present invention, glass fibers are understood to mean any glass fiber described in particular by Frederick T. Wallenberger, James C. Watson and Hong Li, PPG Industries Inc. (ASM Handbook, Vol 21: Composites (#06781G), 2001 ASM International).

[0079] Preferably, the glass fibers are short, having an average length between 2 and 13 mm, preferably 3 to 8 mm, before being incorporated into the composition. Once incorporated into the composition, they preferably have an average length, measured by optical microscopy (e.g. after melting or calcining the matrix), in the range of 50 to 300 μm, in particular 100 to 250 μm.

[0080] The nature of the glass of the glass fibres is in principle of little importance in the practice of the invention, and therefore the glass fibres may be made of any glass, such as E, R, S2, NE or T glass.

[0081] The glass fibres can be solid and / or hollow; advantageously, they are solid.

[0082] Glass fiber is - a circular cross section, preferably with a diameter between 4 μm and 25 μm, in particular from 4 to 15 μm; or it may be either of non-circular cross-section, in particular of elliptical, oval or flat cross-section, preferably with an L / D ratio (L representing the largest dimension of the cross-section of the fibre and D representing the smallest dimension of the cross-section of said fibre) of 2 to 8, in particular of 2 to 4. L and D can be measured by scanning electron microscopy (SEM).

[0083] Additionally, the fibers can have different shapes of non-circular cross-sections, such as star-shaped, flake-shaped, plate-shaped, cross-shaped, polygonal, or ring-shaped.

[0084] The composition of the invention comprises from 30% to 80% by weight, in particular from 30% to 65% by weight, of glass fibres. It may comprise various types of glass fibres and, optionally, in addition to glass fibres, other reinforcing materials such as solid and / or hollow glass beads.

[0085] According to certain embodiments, the content of glass fibers in the composition may vary from 30% to 35% by weight; or from 35% to 40% by weight, or from 40% to 45% by weight; or from 45% to 50% by weight; or from 50% to 55% by weight; or from 55% to 60% by weight; or from 60% to 65% by weight, or from 65% to 70% by weight; or from 70% to 75% by weight; or from 75% to 80% by weight.

[0086] [Additives] The composition according to the invention may also contain one or more additives, which may be chosen in particular from the usual additives such as dyes, stabilizers, surfactants, nucleating agents, brighteners, antioxidants, lubricants, waxes and mixtures thereof.

[0087] The stabilizer can be organic or inorganic stabilizer. The usual stabilizers used with polymers are, for example, phenols, phosphites, UV absorbers, HALS (hindered amine light stabilizers) type stabilizers, or metal iodides. Mention can be made of Irganox® 1010, 245 or 1098 from BASF, Irgafos® 168 or 126 from BASF, Tinuvin® 312 or 770 from BASF, iodide P201 from Ciba, and Nylostab® S-EED from Clariant.

[0088] The lubricant may in particular be a stearate or a wax binder.

[0089] The waxes may be amorphous waxes such as beeswax, silicone waxes, polyethylene waxes, polyethylene oxide waxes, ethylene copolymer waxes, montan waxes and polyether waxes, among others.

[0090] The content of the additives is from 0 to 10% by weight relative to the total weight of the composition.

[0091] According to certain embodiments, the content of the additive in the composition is 0 to 0.5% by weight; or 0.1% to 0.5% by weight; or 0.5% to 1.0% by weight; or 1% to 1.5% by weight; or 1.5% to 2.0% by weight; or 2.0% to 2.5% by weight; or 2.5% to 3.0% by weight; or 3.5% to 4.0% by weight; or 4.0% to 4.5% by weight; or 4. It may vary from 5% to 5.0% by weight; or from 5.0% to 5.5% by weight; or from 5.5% to 6.0% by weight; or from 6.5% to 7.0% by weight; or from 7.0% to 7.5% by weight; or from 7.5% to 8.0% by weight; or from 8.0% to 8.5% by weight; or from 8.5% to 9.0% by weight, or from 9.0% to 9.5% by weight; or from 9.5% to 10.0% by weight.

[0092] The compositions described have excellent dimensional stability in a humid environment and also very good stability of the mechanical properties, especially the modulus of elasticity.

[0093] [Method for producing the composition] According to a second subject, the invention relates to a method for preparing the composition described above.

[0094] This method is (i) a) a polyamide component comprising 20% ​​to 70% by weight of a semi-crystalline aliphatic polyamide having an average of at least 7 carbon atoms per nitrogen atom and having a total acidity, as measured by potentiometric titration, of 70 to 180 μeq / g; b) 30% to 80% by weight glass fibers; and c) 0 to 10% by weight of additives wherein the sum of components (a), (b) and (c) is 100%; and (ii) optionally shaping the mixture obtained in step (i); The process includes the steps of:

[0095] Step (i) may be carried out by any method making it possible to obtain a homogeneous mixture comprising the composition according to the invention and, optionally, other additives, such as melt extrusion, compression or roll milling.

[0096] More specifically, step (i) can be carried out by melt mixing all the components in a "direct" process. The composition according to the invention can also be prepared by dry mixing. Advantageously, the composition can be obtained in granular form, generally by compounding in equipment known to those skilled in the art, such as twin-screw extruders, co-kneaders or internal mixers.

[0097] The compositions according to the invention obtained by the above-mentioned preparation methods can then be converted for further conversions or uses known to those skilled in the art, in particular by injection moulding, calendering or extrusion, preferably by injection moulding. The conversion can be carried out directly, using melt mixing or by dry mixing as described above (step ii).

[0098] The process for preparing the compositions of the present invention may also use a twin screw extruder feeding the extruder without intermediate granulation, or an injection molder with processing equipment known to those skilled in the art.

[0099] [Articles obtained from the composition] The compositions according to the invention are useful for the manufacture of articles, particularly those intended for assembly, whose mechanical properties, such as the modulus of elasticity, do not change significantly when exposed to wet conditions.

[0100] Thus, according to a third subject, the invention relates to an article obtained from the composition described above. It may in particular concern moulded articles, fibres, fabrics, films, sheets, rods or tubes.

[0101] In particular, it may concern mouldings such as parts intended for sporting goods. Among these sporting goods, mention may be made of sports shoes, ice skates, or other articles for winter sports and mountaineering, ski bindings, rackets, sports bats, boards, horseshoes, fins, golf balls and recreational vehicles. In general, mention may also be made of recreational or home improvement items, highway tools or parts of equipment exposed to weather and mechanical attack; protective articles such as helmet visors, glasses, side arms for glasses, etc.

[0102] Mention may also be made of attractive protective components for automotive parts exposed to mechanical and chemical attack, such as headlamp protectors, small parts of all-terrain vehicles, tanks, in particular mopeds, bikes or scooters, screws and bolts, cosmetic articles exposed to mechanical and chemical attack, lipstick containers, pressure gauges, gas bottles, etc.

[0103] Finally, mention may be made in particular of parts for electronic products where lightness is desirable and dimensions must be respected, such as parts for mobile phones, computers, tablets, televisions, digital cameras, digital games consoles, drones or printers.

[0104] [use] According to a fourth object, the present invention relates to the use of the semicrystalline aliphatic polyamides described above for the manufacture of articles having improved stability of their modulus in wet environments.

[0105] According to one embodiment, a semi-crystalline aliphatic polyamide is used as the matrix of the polyamide composition described above.

[0106] The present invention also relates to a method for increasing the stability of the modulus of a composition comprising the semicrystalline polyamide described above. This use is particularly advantageous for very hard compositions having a tensile modulus of more than 7000 MPa, in particular between 10000 MPa and 25000 MPa.

[0107] The invention is explained in more detail in the following examples. EXAMPLES

[0108] The materials used in the exemplified compositions are detailed below. polyamide: PA610:PA610A is obtained by polycondensation of sebacic acid and hexanediamine, charged in an excess of 1.03% by weight with respect to the total amount of monomers in stoichiometric ratio, according to the following process: All monomers are charged in a reactor equipped with an agitator. To improve the heat exchange and promote the melting of the monomers, 15% by weight of water is added with respect to the total amount of monomers. The reactor is then inerted by a vacuum / nitrogen cycle to remove residual oxygen, then heated to a first hold of 160-170°C under 8 bar. After 1 hour, the temperature of the mixture is increased to 240°C at a pressure of 17 bar. The pressure is then reduced to atmospheric pressure, while the temperature is gradually increased to 255°C. At this temperature, the polycondensation reaction is carried out under nitrogen flushing. The reaction is terminated when the target viscosity is reached. The polyamide is then extruded and granulated. The resulting polymer is free of phosphoric acid and has the intrinsic viscosity shown in Table 1 below.

[0109] PA610B is obtained by polycondensation of sebacic acid and hexanediamine, which are charged in 1.24% excess by weight with respect to the total amount of monomers in stoichiometric ratio, together with 3600 ppm KOH, according to the process described above. The polymer obtained is phosphoric acid-free and has the intrinsic viscosity shown in Table 1 below.

[0110] PA610C is obtained by polycondensation of hexanediamine and sebacic acid in stoichiometric ratio with 3600 ppm KOH according to the process described above. The obtained polyamide is phosphoric acid-free and has the intrinsic viscosity shown in Table 1.

[0111] PA11:PA11A is obtained by polycondensation as follows: 11-aminoundecanoic acid, 15% by weight of water and 0.67% by weight of adipic acid (these two amounts are calculated relative to the amount of 11-aminoundecanoic acid) are placed in a reactor, which is then placed under an inert atmosphere. The temperature of the reaction medium is then increased to 235°C, while maintaining the stirring. The reaction medium is maintained at 235°C for 1 hour 30 minutes under a pressure of 20 bar. The pressure is then reduced to 12 bar, while maintaining the temperature at 235°C. This material is then transferred to a polymerizer at 235°C under nitrogen flushing. The temperature is maintained for 1 hour 30 minutes under nitrogen flushing. The material is then extruded in the form of granules. The polyamide obtained is free of phosphoric acid and has an intrinsic viscosity as shown in Table 1.

[0112] PA11B is obtained by polycondensation as described for PA11A, except that adipic acid is replaced by 0.47% by weight of decanediamine relative to the amount of 11-aminoundecanoic acid. The resulting polyamide is phosphoric acid-free and has the intrinsic viscosity shown in Table 1.

[0113] PA11C is obtained by polycondensation as described for PA11A, except that adipic acid is replaced by 0.25% by weight of KOH relative to the amount of 11-aminoundecanoic acid. The resulting polyamide is phosphoric acid-free and has the intrinsic viscosity shown in Table 1.

[0114] [Reinforcement material] GF1: Flat glass fiber with a cross section of 28 μm in long diameter, 7 μm in short diameter, and 3 mm in average length, sold by Nitto Boseki Co., Ltd. under the name CSG3PA-820S; GF2: Glass fiber with a circular cross section, diameter 10 μm, average length 3 mm, sold by Nitto Boseki Co., Ltd. under the name CSX3J451.

[0115] The properties of the polyamide and of the resulting compositions are measured according to the following protocol.

[0116] [Intrinsic viscosity] Intrinsic viscosity is measured according to the ISO 307:2007 standard, except that a 0.5% by weight solution in m-cresol is used and the measurement is performed at 20°C.

[0117] [Phosphate content] The phosphate content of polyamide is measured using the Avance 400NEO console sold by BRUKER. 31 Quantification was carried out by NMR. A quantity of 400 mg of polyamide was solubilized overnight at room temperature in 3 ml of a mixture of HFIP / CD2Cl2 (volume ratio 2:1). Analysis was carried out using the internal standard method (Irgafos 168). 20 mg of Irgafos was added to the previous solution (this makes it possible to know the relationship between the amount of phosphorus and the mass of phosphorus necessary for the calculation of the phosphoric acid content).

[0118] [Total acidity] The acidity is measured according to the following method: 1 g of polyamide is dissolved hot at 130°C in 80 ml of benzyl alcohol. The sample is then cooled to 80°C. It is then analyzed by potentiometric titration with a 0.02 N solution of tetrabutylammonium hydroxide using a Metrohm titrator (model 888) combined with a pH electrode. The volume of titration solution added at the inflection point of the potential of the solution corresponds to the equivalent volume Veq, from which the total acidity is calculated according to the following formula:

number

[0119] [Total basicity] The basicity is measured according to the following method: 1 g of polyamide is dissolved hot at 130°C in 80 ml of meta-cresol. The sample is then cooled to 80°C. It is then analyzed by potentiometric titration with a 0.02N solution of perchloric acid in acetic acid using a Metrohm titrator (model 888) combined with a pH electrode. The volume of titrant solution added at the inflection point of the potential of the solution corresponds to the equivalent volume Veq, from which the total basicity is calculated according to the following formula:

number

[0120] [Water content] From the obtained composition, 100 x 100 x 1 mm pieces were produced by injection molding on an ENGEL VICTORY 500,160T hydraulic press using the following parameters: 3 Sheets were prepared with the following dimensions: - Injection temperature (feed / nozzle): 265℃ / 280℃ - Mold temperature: 100℃ - Hold time: 10 seconds - Material holding pressure: 700 bar - Cooling time: 35 seconds

[0121] These sheets are then dried in an oven at 80° C. until the moisture content is 0.02% by weight. Next, the sheets are weighed and then placed in warm water at 23° C. or in a space adjusted to 23° C. and a relative humidity of 50%.

[0122] Weighing makes it possible to determine the amount of water absorbed by the material by monitoring the weight of the sheet as a function of the time spent in each medium, and the weighing is carried out until three identical measurements are obtained, indicating that water absorption is complete.

[0123] At the end of the experiment, the water was desorbed in an oven at 170°C for 20 minutes, and then the solution was titrated with Hydranal containing the reagent "Solvent E". E The moisture content is checked on a sheet piece of about 1 g by titrating the desorbed moisture according to the Karl Fischer method with a titrator (Metrohm Titrino 795KFT capacity model) using a 1 g titrator.

[0124] Elastic Modulus (E) Dumbbells according to ISO527-2 1A were produced by injection moulding on an ENGEL VICTORY 500,160T hydraulic press using the following parameters: - Injection temperature (feed / nozzle): 285℃ / 295℃ - Mold temperature: 100℃ - Hold time: 10 seconds - Material holding pressure: 700 bar - Cooling time: 15 seconds

[0125] The tensile modulus was measured in the dry state (Edry) and once saturated with water (Esat), i.e. after 1096 hours in water at 70°C and 1272 hours in water at 23°C, respectively. The tensile tests are performed on an MTS 810 machine from MTS Systems equipped with hydraulic jaws. The tensile tests are performed at 23°C at a speed of 1 mm / min for modulus and 5 mm / min for stress measurements. The elastic modulus is calculated according to ISO 527-1 (2012).

[0126] [Break stress (σ B )] The stress at break was determined as the maximum stress observed in the stress-strain curve resulting from a tensile test performed according to the ISO 527-1 (2012) standard.

[0127] Examples 1 to 3 Compositions containing polyamide and glass fibers were prepared in a Coperion ZSK26MC twin screw extruder equipped with a lateral feed path for introducing the glass fibers as indicated in Table 1, using the following parameters: Machine temperature: 270℃ Screw speed: 250 rpm Extruder outlet throughput: 16kg / h The polyamide is fed into the main hopper.

[0128] The results obtained with the compositions of the present invention are shown in Table 1 below. [Table 1] [Table 2]

[0129] Comparative examples C1~C3 Examples 1 to 3 are repeated except that the polyamide in the composition is replaced with that shown in Table 1 above. The compositions obtained were analyzed in terms of moisture absorption and mechanical properties, in particular modulus and stress at break, according to the protocol detailed above.

[0130] All the results, summarized in Tables 1 and 2, demonstrate that for each polyamide studied, the composition according to the invention exhibits lower water absorption.

[0131] Furthermore, the tensile modulus E and breaking stress σ before and after moisture sorption B Studies of mechanical properties such as ΔE and ΔE / ... B is more limited for the compositions according to the invention (32% and 34%) compared to the comparative composition (63%).

[0132] Thus, the examples demonstrate that the semi-crystalline aliphatic polyamide compositions according to the invention also exhibit improved dimensional stability and mechanical properties, particularly with regard to modulus, that are robust to moisture.

[0133] Therefore, by adjusting the nature and content of the amine and carboxyl groups at the chain ends, it is possible to limit the moisture sorption of semi-crystalline aliphatic polyamide compositions, thereby improving their dimensional stability as well as the stability of their mechanical properties in humid environments.

[0134] [References list] US2014 / 0342145A1 US2017 / 0029621A1 JP2017 / 155157

Claims

1. (a) 20% to 70% by weight of a polyamide component comprising an aliphatic semi-crystalline polyamide having an average of at least 7 carbon atoms per nitrogen atom; (b) 30% to 80% by weight glass fibers; and (c) 0 to 10 wt. % of additives wherein the sum of components (a), (b) and (c) equals 100%; 1. A composition characterized in that the semi-crystalline aliphatic polyamide has a total acidity, as measured by potentiometric titration, of 100 to 150 μeq / g and a total basicity, as measured by potentiometric titration, of less than 40 μeq / g.

2. 10. The composition of claim 1, wherein the semi-crystalline aliphatic polyamide has a total basicity between 10 μeq / g and 30 μeq / g as measured by potentiometric titration.

3. 2. The composition according to claim 1, wherein the aliphatic semi-crystalline polyamide is a polyamide of the XY type obtained by polycondensation of at least one diamine with at least one dicarboxylic acid.

4. 4. The composition according to claim 3, wherein the aliphatic semi-crystalline polyamide of XY type is obtained by polycondensation of at least one linear or branched aliphatic diamine having from 5 to 12 carbon atoms with at least one linear or branched aliphatic dicarboxylic acid having from 9 to 18 carbon atoms.

5. 2. The composition according to claim 1, wherein the aliphatic semi-crystalline polyamide is a Z-type polyamide obtained by polycondensation of at least one aminocarboxylic acid and / or at least one lactam.

6. 6. The composition of claim 5, wherein the at least one aminocarboxylic acid and / or the at least one lactam has 11 or 12 carbon atoms.

7. 2. The composition of claim 1, wherein the aliphatic semi-crystalline polyamide is selected from the group consisting of PA59, PA510, PA69, PA512, PA612, PA109, PA610, PA1010, PA1012, PA11, PA12 and PA1212.

8. The composition of claim 1 , wherein the glass fibers are glass fibers of circular or non-circular cross section.

9. The composition of claim 1 comprising 30% to 65% by weight of glass fibers.

10. 2. The composition of claim 1, wherein the semi-crystalline polyamide has an intrinsic viscosity in the range of 0.85 to 1.30 dl / g, measured according to the ISO 307:2007 standard but in a 0.5 wt. % m-cresol solution at 20°C.

11. 11. An article obtainable from the composition according to any one of claims 1 to 10.

12. 12. An article according to claim 11, characterized in that it is obtained by injection.

13. A method for producing a composition according to any one of claims 1 to 10, comprising the steps of: (i) a) 20% to 70% by weight of a polyamide component comprising an aliphatic semi-crystalline polyamide having an average of at least 7 carbon atoms per nitrogen atom and having a total acidity, as measured by potentiometric titration, between 70 and 180 μeq / g; b) 30% to 80% by weight glass fibers; and c) 0 to 10 wt. % of additives wherein the sum of components (a), (b) and (c) is 100%; and (ii) optionally shaping the mixture obtained in step (i). A method comprising:

14. 1. Use of an aliphatic semi-crystalline polyamide having an average of at least 7 carbon atoms per nitrogen atom and having a total acidity, as measured by potentiometric titration, between 70 and 180 μeq / g, to produce an article having improved stability of elastic modulus in a wet environment.

15. 1. Use of an aliphatic semi-crystalline polyamide having an average of at least 7 carbon atoms per nitrogen atom and having a total acidity, as measured by potentiometric titration, between 70 and 180 μeq / g, to produce an article having improved dimensional stability.

16. 16. Use according to claim 14 or 15, wherein an aliphatic semi-crystalline polyamide is used as the matrix of the composition according to any one of claims 1 to 10.