Patent Description:
In particular the present invention it relates to impact modified transparent polyamide composition comprising a multistage polymer.

More particularly the present invention relates to the use of multistage polymer as impact modifier in a transparent polyamide composition.

Among high-performances polymers, transparent polyamides are particularly advantageous as they exhibit numerous mechanical properties, such as impact strength, tensile strength and/or compressive strength, high resistance to external attack (such as heat, chemicals, UV radiation, and the like), as well as transparency. The arrival has consequently been seen of objects based on polyamides, such as, for example, spectacle frames, various housings, motor vehicle accessories, surgical materials, packaging or sporting goods.

In the field of transparent polyamides with high light-permeability, two types of polymer are known, amorphous ones which have only a glass transition temperature and microcrystalline ones which have a glass transition temperature and a melting point.

Amorphous polyamides and microcrystalline polyamides have an improved transparency but have usually a notched impact strength according to Charpy that does not go beyond the range of 14kJ/m2 to <NUM> kJ/m2 at <NUM>.

One objective of the present invention is to propose transparent polyamide polymer composition with increased impact resistance.

Another objective of the present invention is to propose a transparent polyamide polymer composition with increased impact resistance, while keeping still acceptable the optical properties of said composition. Optical properties relates in particular to minimising the opacity (haze) and maximising the light transmission of moulded articles produced from the impact modified polyamide composition by moulding.

Another objective of the present invention is also to provide a transparent polyamide polymer composition with increased impact resistance, while keeping still acceptable the other mechanical properties. Other mechanical property relates in particular to avoid an important decrease in the modulus while improving the impact resistance of a moulded articles produced from the impact modified transparent polyamide composition.

The document <CIT> discloses transparent colourless amorphous polyamide and moulded articles. The notched impact resistance at <NUM> is only 12kJ/m2. The composition comprises no impact modifier.

The document <CIT> discloses transparent polyamide moulding materials having improved transparency, resistance to chemicals and high permanent fatigue strength. The moulding can comprises an impact modifier such as terpolymers made of ethylene glycidyl methacrylate or maleic anhydride grafted polyethylene or propylene.

The document <CIT> discloses a transparent polyamide molding compositon. The molding composition comprises at least one transparent homopolyamide and/or copolyamide and a polyesteramide for increasing impact strength. As one of the comparative examples a core-shell impact modifier is used.

The document <CIT> discloses polyamide moulding compounds for varnish free, tough casings with high gloss surface. The moulding compound contains two amorphous copolyamides and at least one impact modifier. A preferred impact modifier is a core-shell impact modifier based on metacrylates, butadiene and styrene (MBS copolymer).

The document <CIT> discloses a polyamide moulding compound and moulded articles produced there from. The polyamides moulding compound comprises a functionalized blockcopolymer as impact modifier. Core-shell polymers are used between others polymeric materials as impact modifiers in the comparative examples only.

Surprisingly it has been found that a polymer composition comprising.

characterized that the composition fulfills the following formula <MAT> wherein k represents the ratio in mol% of aromatic groups in the polyamide PA, l represents the ratio in mol% of aromatic groups in the multistage polymer and the parameter t is at most <NUM>, is having an impact strength increase while having a light transmission of at least <NUM>% (for a sheet of <NUM> thickness).

Surprisingly it has also been found that a polymer composition comprising.

characterized that the composition fulfills the following formula <MAT> wherein k represents the ratio in mol% of aromatic groups in the polyamide PA, l represents the ratio in mol% of aromatic groups in the multistage polymer and the parameter t is at most <NUM>, is having an impact strength increase while still having a haze below <NUM>% (for a sheet of <NUM> thickness).

Surprisingly it has additionally been found that a polymer composition comprising.

characterized that the composition fulfills the following formula <MAT> wherein k represents the ratio in mol% of aromatic groups in the polyamide PA, l represents the ratio in mol% of aromatic groups in the multistage polymer and the parameter t is at most <NUM>, is having an impact strength increase while still having a haze below <NUM>% and a light transmission of at least <NUM>% (for a sheet of <NUM> thickness).

Surprisingly it has also been found that a method for manufacturing a polymer composition comprising the step of blending a transparent polyamide PA and a multistage polymer in form of core shell particles characterized that the composition fulfils the following formula <MAT> wherein k represents the ratio in mol% of aromatic groups in the polyamide PA, l represents the ratio in mol% of aromatic groups in the multistage polymer and the parameter t is at most <NUM>, yields to a polymer composition having an impact strength increase while having a light transmission of at least <NUM>% and still having a haze below <NUM>% (for a sheet of <NUM> thickness) in comparison to the same composition without multistage polymer.

According to a first aspect, the present invention relates to a polyamide polymer composition comprising.

characterized that the composition fulfills the following formula <MAT> wherein k represents the ratio in mol% of aromatic groups in the polyamide PA, l represents the ratio in mol% of aromatic groups in the multistage polymer and the parameter t is at most <NUM>, and characterized that the polyamide is amorphous or microcrystalline and the polyamide is transparent by having light transmission of a sheet of <NUM> thickness that is least <NUM>% measured at <NUM> (ISO <NUM>-<NUM>/<NUM>.

According to a second aspect, the present invention relates to a polyamide polymer composition comprising.

In a third aspect the present invention relates to a method for manufacturing a polymer composition comprising the step of blending a transparent polyamide PA and a multistage polymer in form of core shell particles characterized that the composition fulfils the following formula <MAT> wherein k represents the ratio in mol% of aromatic groups in the polyamide PA, l represents the ratio in mol% of aromatic groups in the multistage polymer and the parameter t is at most <NUM>, and characterized that the polyamide is amorphous or microcrystalline and the polyamide is transparent by having light transmission of a sheet of <NUM> thickness that is least <NUM>% measured at <NUM> (ISO <NUM>-<NUM>/<NUM>.

By the term "transparent" as used is understood a light transmission of at least <NUM>% measured on a plate of <NUM> thickness at <NUM> (ISO <NUM>-<NUM>/<NUM>).

By the term "copolymer" as used is denoted that the polymer consists of at least two different monomers.

By "multistage polymer" as used is denoted a polymer formed in sequential fashion by a multi-stage polymerization process. Preferred is a multi-stage emulsion polymerization process in which the first polymer is a first-stage polymer and the second polymer is a second-stage polymer, i.e., the second polymer is formed by emulsion polymerization in the presence of the first emulsion polymer, with at least two stages that are different in composition.

By the term "(meth)acrylic" as used is denoted all kind of acrylic and methacrylic monomers.

By the term "(meth)acrylic polymer" as used is denoted that the (meth)acrylic polymer comprises essentially polymers comprising (meth)acrylic monomers that make up 50wt% or more of the (meth)acrylic polymer.

With regard to the polyamide of the composition of the present invention, it is an amorphous or microcrystalline polyamide.

Polyamides are termed as amorphous, if they show in dynamic differential calorimetry (differential scanning calorimetry, DSC) according to ISO <NUM>-<NUM>/<NUM> at a heating rate of <NUM>/min, a melting enthalpy ΔH of at most <NUM> J/g, preferably 3J/g and more preferably at most <NUM> J/g.

Polyamides are termed as microcrystalline, if they show in dynamic differential calorimetry (differential scanning calorimetry, DSC) a glass transition temperature Tg and a melting point with a melting enthalpy ΔH of at least <NUM> J/g and if they are transparent.

The polyamide of the composition according to the invention has a glass transition temperature Tg of at least <NUM>. The Tg is measured with dynamic differential calorimetry (differential scanning calorimetry, DSC) to according to ISO <NUM>-<NUM>/<NUM>. The glass transition temperature Tg of the polyamide measured according ISO <NUM>-<NUM>/<NUM> is preferably from <NUM> to <NUM> and more preferably from <NUM> to <NUM>.

The polyamide of the composition according to the invention is transparent. By transparent is meant that the light transmission of a sheet of <NUM> thickness is least <NUM>% measured at <NUM> (ISO <NUM>-<NUM>/<NUM>), advantageously at least <NUM>% and particularly preferred at least <NUM>%.

The polyamide (PA) of the composition of the present invention is chosen from a homopolyamide or a copolyamide.

The homopolyamide of the composition of the present invention is not made from a lactam or an aminocarboxylic acid. The homopolyamide of the present invention is made from a diamine and a dicarboxylic acid. The general formula (<NUM>) of this homopolyamide is.

wherein XX represents a diamine and YY represent a dicarboxylic acid also simply called diacid.

Diamines XX are aliphatic diamines linear or not, or cycloaliphatic diamines, or diamines with partially aromatic structures. Preferably the diamine is aliphatic branched or cycloaliphatic.

The XX diamine can be a cycloaliphatic diamine. Among cycloaliphatic diamines, those comprising two rings are preferred. They correspond in particular to the following general formula :
<CHM>
in which :
R1 to R4 represent identical or different groups chosen from a hydrogen atom or alkyl groups of <NUM> to <NUM> carbon atoms and X represents either a single bond or a divalent group composed:.

More preferably, the cycloaliphatic diamine of the polyamide according to the invention is chosen from bis(<NUM>,<NUM>-dialkyl-<NUM>-aminocyclohexyl) methane, bis(<NUM>,<NUM>-dialkyl-<NUM>-aminocyclohexyl)ethane, bis(<NUM>,<NUM>-dialkyl-<NUM>-aminocyclohexyl)propane, bis(<NUM>,<NUM>-dialkyl-<NUM>-aminocyclohexyl)butane, bis(<NUM>-methyl-<NUM>-aminocyclohexyl)methane (BMACM or MACM), p-bis(aminocyclohexyl)methane (PACM) and isopropylidenedi(cyclohexylamine) (PACP).

A non-exhaustive list of cycloaliphatic diamines can be found in the article "<NPL>).

More preferably still, and with a view to obtaining a transparent copolyamide, the cycloaliphatic diamine is chosen from bis(<NUM>-methyl-<NUM>-aminocyclohexyl)methane (BMACM or MACM) p-bis(aminocyclohexyl)methane (PACM) and isopropylidenedi(cyclohexylamine) (PACP).

The XX diamine can have a partially aromatic structure. Mention may be made, among arylaromatic diamines, of <NUM>,<NUM>-xylylenediamine (also known as meta-xylylenediamine or MXDA), <NUM>,<NUM>-xylylenediamine (also known as para-xylylenediamine or PXDA) and their mixtures.

The XX diamine of formula (<NUM>) can be aliphatic and linear, and has the general formula H<NUM>N-(CH<NUM>)a-NH<NUM>. Preferably, the XX diamine is chosen among butanediamine (a=<NUM>), pentanediamine (a=<NUM>), hexanediamine (a=<NUM>), heptanediamine (a=<NUM>), octanediamine (a=<NUM>), nonanediamine (a=<NUM>), decanediamine (a=<NUM>), undecanediamine (a=<NUM>), dodecanediamine (a=<NUM>), tridecanediamine (a=<NUM>), tetradecanediamine (a=<NUM>), hexadecanediamine (a=<NUM>), octadecanediamine (a=<NUM>), octadecenediamine (a=<NUM>), eicosanediamine (a=<NUM>), docosanediamine (a=<NUM>), and diamines obtained from dimmer fatty diacids.

The XX diamine of formula (<NUM>) can be aliphatic and branched. Preferably, the XX diamine is chosen among <NUM>-methyl-<NUM>,<NUM>-pentamethylenediamine, trimethyl-<NUM>,<NUM>-hexanediamine, <NUM>-methylnonamethylenediamine, and their isomers or mixtures thereof.

Diacids YY of formula (<NUM>) are aliphatic dicarboxylic acids, or aromatic dicarboxylic acids, or cycloaliphatic acids.

The YY dicarboxylic acid could be aliphatic and linear, and has the general formula HOOC-(CH<NUM>)b-COOH. Preferably, it has from <NUM> to <NUM> carbon atoms. More preferably, it can be chosen among sebacic acid (b=<NUM>, <NUM> carbon atoms ), dodecanedioic acid (b=<NUM>, <NUM> carbon atoms), tetradecanedioic acid (b=<NUM>, <NUM> carbon atoms), octadecanedioic acid (b=<NUM>, <NUM> carbon atoms), and dimer fatty diacids with b=<NUM> (<NUM> carbon atoms).

The dimer fatty acids mentioned above are dimerized fatty acids obtained by oligomerization or polymerization of unsaturated monobasic fatty acids comprising a long hydrocarbon chain (such as linoleic acid and oleic acid), as described in particular in the document <CIT>.

The YY dicarboxylic acid could be aromatic. Preferably, it is chosen among terephthalic acid, isophthalic acid, substituted aromatic dicarboxylic acid, for example <NUM>,<NUM>-naphtalene dicarboxylic acid and <NUM>-t-butylisophthalic acid.

The YY dicarboxylic acid could be cycloaliphatic, with at least one cyclohexane ring. Preferably, this cycloaliphatic diacid is <NUM>,<NUM>-cyclohexanedicarboxylic acid, or <NUM>,<NUM>-cyclohexanedicarboxylic acid.

The molar proportions of XX diamine and of YY diacid of the formula (<NUM>) are preferably stoichiometric.

Among the combinations which can be envisaged for a homopolyamide according to formula (<NUM>), symbolizing bis(<NUM>-methyl-<NUM>-aminocyclohexyl)methane (BMACM) by the letter B, p-bis(aminocyclohexyl)methane (PACM) by the letter P, <NUM>-methyl-<NUM>,<NUM>-pentamethylenediamine by the letters MPMD, trimethyl-<NUM>,<NUM>-hexanediamine by the letters TMD as diamins XX; and isophthalic acid by the letter I as diacid or the diacid YY with general formula HOOC-(CH<NUM>)y-COOH comprising y methylene groups by the number y+<NUM> for the carbon atoms of the diacid, the following homopolyamides are of particularly pronounced interest: TMD. <NUM>, TMD. <NUM>, TMD. <NUM>, TMD. <NUM>, MPMD. <NUM>, MPMD. <NUM>, MPMD. <NUM>, MPDM. Preferably the homopolyamide is chosen from TMD. <NUM>, and P. <NUM>, and more preferably from TMD. <NUM>, and P.

The copolyamide also called copolymer polyamide of the composition of the present invention comprises at least two distinct repeat units, these distinct units being formed from the two corresponding monomers or comonomers. Copolyamides are thus prepared from two or more monomers or comonomers chosen from an amino acid, a lactam, a dicarboxylic acid and a diamine.

The copolyamide according to the invention comprises at least two units (respectively represented "Z" and "XX. YY") and corresponds to (that is to say, comprises at least) the following general formula (<NUM>):.

wherein Z represents a lactam L and/or an amino acid A, and XX represents a diamine and YY represents a dicarboxylic acid.

Diamines are aliphatic diamines linear or not, or cycloaliphatic diamines, or diamines with partially aromatic structures. Preferably the diamines are aliphatic branched or cycloaliphatic.

Diacids are aliphatic dicarboxylic acids, or aromatic dicarboxylic acids, or cycloaliphatic acids.

Preferably the copolyamide according to formula (<NUM>) in the composition of the of the invention, has molar content of Z is from <NUM> mol% to <NUM> mol%, the molar content of diamine XX being from <NUM> mol % to <NUM> mol% and the molar content of diacid YY also being from <NUM> mol% to <NUM> mol%. More preferably the molar content of Z is from <NUM> mol % to <NUM> mol%, the molar content of diamine XX being from <NUM> mol % to <NUM> mol% and the molar content of diacid YY also being from <NUM> mol% to <NUM> mol%.

The choice of such molar contents makes it possible to obtain, in the majority of cases, a copolyamide with a high light transmission.

The lactam L is chosen from γ-pyrrolidone (lactame <NUM>), piperidinone (lactam <NUM>), ε-caprolactam (lactam <NUM>), enantholactam (lactam <NUM>), caprylolactame (lactam <NUM>), pelargolactam (lactam <NUM>), decanolactam (lactam <NUM>) undecanolactam (lactam <NUM>) and laurolactam (lactam <NUM>) and preferably from laurolactam.

The aminocarboxylic acid A is chosen among <NUM>-aminononanoic acid, <NUM>-aminodecanoic acid, <NUM>-aminododecanoic acid and <NUM>-aminoundecanoic acid and its derivatives, in particular N-heptyl-<NUM>-aminoundecanoic acid, and preferably from <NUM>-aminododecanoic acid and <NUM>-aminoundecanoic acid.

In place of one amino acid A or lactam L, it might also be possible to envisage a mixture of two, three or more amino acids and/or lactams. However, the copolyamides formed would then comprise three, four or more units respectively. It is specified that the specific case of such a copolyamide comprising three or more distinct units is described by the formula (<NUM>).

The XX diamine of formula (<NUM>) is chosen among the same diamine as the diamine given for formula (<NUM>).

The YY diacid of formula (<NUM>) is chosen among the same diacids as the diacids given for formula (<NUM>).

Among the combinations which can be envisaged for the copolyamide of general formula (<NUM>), the unit resulting from <NUM>-aminoundecanoic acid being symbolized by the number <NUM>, the unit resulting from laurolactam symbolized by the number <NUM>, the unit resulting from terephthalic acid symbolized by the letter T, the following copolyamides are of particularly pronounced interest: <NUM>/B. I, <NUM>/B. T, <NUM>/B. I, <NUM>/B. T, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/P. <NUM>, and <NUM>/P.

Preferably the copolyamide of formula (<NUM>) is chosen from <NUM>/B. I, <NUM>/B. T, <NUM>/B. I, <NUM>/B. T, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM> and <NUM>/B. <NUM>, more preferably from <NUM>/B. I, <NUM>/B. I, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/B. <NUM>, <NUM>/B.

According to a third alternative form of the polyamide of the composition of the invention, the (co)monomer or unit Z in the general formula (<NUM>) of the copolyamide PA Z/ XX. YY is a unit corresponding to the formula (3a) :.

Diamines are aliphatic diamines linear or not, or cycloaliphatic diamines, or diamines with partially aromatic structures.

Very clearly, the specific cases for which the XX. WW comonomers or units are strictly identical, are excluded in formulas (3a) and (3b), as this would be already the homopolyamide of formula (<NUM>).

The VV diamine can be a cycloaliphatic diamine. Reference will be made to that which was described above as cycloaliphatic diamine for the diamine of the XX. YY comonomer or unit.

The VV diamine can have a partially aromatic structure. Reference will be made to that which was described above as partially aromatic diamine for the diamine of the XX. YY comonomer or unit.

The VV diamine can be aliphatic and linear, and has the general formula H<NUM>N-(CH<NUM>)a-NH<NUM>. Preferably, the XX diamine is chosen among butanediamine (a=<NUM>), pentanediamine (a=<NUM>), hexanediamine (a=<NUM>), l'heptanediamine (a=<NUM>), octanediamine (a=<NUM>), nonanediamine (a=<NUM>), decanediamine (a=<NUM>), undecanediamine (a=<NUM>), dodecanediamine (a=<NUM>), tridecanediamine (a=<NUM>), tetradecanediamine (a=<NUM>), hexadecanediamine (a=<NUM>), octadecanediamine (a=<NUM>), octadecenediamine (a=<NUM>), eicosanediamine (a=<NUM>), docosanediamine (a=<NUM>), and diamines obtained from dimmer fatty diacids.

The VV diamine can be aliphatic and branched. Preferably, the VV diamine is chosen among <NUM>-methyl-<NUM>,<NUM>-pentamethylenediamine, trimethyl-<NUM>,<NUM>-hexanediamine, <NUM>-methylnonamethylenediamine, and their isomers or mixtures thereof.

The WW dicarboxylic acid could be aliphatic and linear, and has the general formula HOOC-(CH<NUM>)b-COOH. Preferably, it has from <NUM> to <NUM> carbon atoms. More preferably, it can be chosen among sebacic acid (b=<NUM>, <NUM> carbon atoms ), dodecanedioic acid (b=<NUM>, <NUM> carbon atoms), tetradecanedioic acid (b=<NUM>, <NUM> carbon atoms), octadecanedioic acid (b=<NUM>, <NUM> carbon atoms), and dimer fatty diacids with b=<NUM> (<NUM> carbon atoms).

The WW dicarboxylic acid could be aromatic. Preferably, it is chosen among terephthalique acid, isophthalique acid, substituted aromatic dicarboxylic acid, for example <NUM>,<NUM>-naphtalene dicarboxylic acid and <NUM>-t-butylisophthalic acid.

The WW dicarboxylic acid could be cycloaliphatic, with at least one cyclohexane ring. Preferably, this cycloaliphatic diacid is <NUM>,<NUM>-cyclohexanedicarboxylic acid, or <NUM>,<NUM>-cyclohexanedicarboxylic acid.

For the preferred choice of the WW diacid of the VV. WW comonomer or unit in the formula (3a), reference will be made to that which was described above as preferred diacid for the YY diacid of the XX. YY comonomer or unit described in formula (<NUM>).

The molar proportions of VV diamine and of WW diacid of the formulas (3a) and (3b) are preferably stoichiometric.

Among the combinations which can be envisaged for the copolyamide of composition VV. YY, the WW diacid comprising w carbon atoms by the number w, the choice will in particular be made of the copolyamides corresponding to one of the formulae chosen from <NUM>/B. I, <NUM>/B. T, <NUM>/B. I, <NUM>/B. T, <NUM>/B. I, <NUM>/B. T, <NUM>/B. I, <NUM>/B. T, <NUM>/P. I, <NUM>/P. T, <NUM>/P. I, <NUM>/P. T, <NUM>/P. I, <NUM>/P. T, <NUM>/P. I, <NUM>/P. T, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, and B. <NUM>, more preferably B. <NUM>, <NUM>/B. I, <NUM>/B. I, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/B. <NUM>, <NUM>/B. <NUM>, and <NUM>/P. <NUM> preferably <NUM>/B. I, <NUM>/B. T, <NUM>/B. I, <NUM>/B. T, <NUM>/P. I, <NUM>/P. T, <NUM>/P. I, <NUM>/P. T, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/B. <NUM>, and <NUM>/B. <NUM>, more preferably <NUM>/B. I, <NUM>/B. I, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM> and <NUM>/B.

According to an additional aspect of the invention, the copolyamide described by the general formula (<NUM>) and/or formula (<NUM>) additionally comprises at least one third unit which is represented below as UU. TT in the formula (<NUM>) :.

wherein UU represents a diamine and TT represents a dicarboxylic acid and Z represents a lactam L and /or an amino acid A.

The diamines UU of formula (<NUM>) are aliphatic diamines linear or not, or cycloaliphatic diamines, or diamines with partially aromatic structures. Preferably, diamines UU are aliphatic branched or cycloaliphatic.

The diacids TT are aliphatic dicarboxylic acids, or aromatic dicarboxylic acids, or cycloaliphatic acids. Preferably at least one of the diacid YY or TT in formula (<NUM>) is a aromatic dicarboxylic acid.

The lactam L and/or an amino acid A for the Z in formula (<NUM>) are the same as defined before.

Very clearly, the specific cases for which the XX. TT comonomers or units are strictly identical, are excluded.

In an advantageous version of the invention, the molar content of Z is from <NUM> mol% to <NUM> mol%, the molar content of diamine mixture XX+UU being from <NUM> mol% to <NUM> mol% and the molar content of diacid mixture YY+TT also being from <NUM> mol% to <NUM> mol%.

In preferred version of the invention, the molar content of Z is from <NUM> mol% to <NUM> mol%, the molar content of diamine XX being from <NUM> mol% to <NUM> mol% and the molar content of diacid YY also being from <NUM> mol% to <NUM> mol%.

The molar proportions of UU diamine and of TT diacid of the formula (<NUM>) are preferably stoichiometric.

In the present description of the formula (<NUM>) and (<NUM>), the term "at least" means that the copolyamide according to the invention comprises the formula which has been made explicit, respectively having <NUM> and having <NUM> units comprising the first <NUM> units, but this formula of <NUM> units or of <NUM> units can be included in a formula of a copolyamide additionally comprising yet other different units. A copolyamide according to the invention can thus exhibit <NUM>, <NUM>, or <NUM> etc. different units, provided that they comprise at least the <NUM> units Z/ XX. YY or the <NUM> units Z/ XX.

Among the combinations which can be envisaged for the copolyamide of composition Z/ XX. TT , the TT diacid comprising t carbon atoms by the number t, the choice will in particular be made of the copolyamides corresponding to one of the formula chosen from <NUM>/B. T, <NUM>/B. T, <NUM>/P. T, <NUM>/P. T, <NUM>/B. I, <NUM>/B. T, <NUM>/B. I, <NUM>/B. T, <NUM>/B. I, <NUM>/B. T, <NUM>/B. I, <NUM>/B. T, <NUM>/P. I, <NUM>/P. T, <NUM>/P. I, <NUM>/P. T, <NUM>/P. I, <NUM>/P. T, <NUM>/P. I, <NUM>/P. T, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, <NUM>/P. <NUM>, and <NUM>/P. <NUM>, preferably <NUM>/B. T, <NUM>/B. T, <NUM>/P. T, <NUM>/P. T, <NUM>/B. I, <NUM>/B. I, <NUM>/B. T, <NUM>/B. T, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/B. <NUM>, <NUM>/P. <NUM>, <NUM>/P. T, <NUM>/P. I, <NUM>/P. I, and <NUM>/P. T, more preferably <NUM>/B. T, <NUM>/B. T, <NUM>/P. T, <NUM>/P. T, <NUM>/B. I, <NUM>/B. I, <NUM>/B. T, and <NUM>/B.

In one preferred embodiment the transparent PA in accordance with the formula (<NUM>), or formula (<NUM>) and/or formula (3b), or formula (<NUM>) comprises not aromatic functions.

A composition of a transparent PA in accordance with the formula (<NUM>), or formula (<NUM>) and/or formula (3b), or formula (<NUM>), can additionally comprise at least one second polymer.

Advantageously, this second polymer can be chosen from a semicrystalline polyamide, an amorphous polyamide, a semicrystalline copolyamide, an amorphous copolyamide, a polyetheramide, a polyesteramide and their blends.

The multistage polymer of the composition according to the invention has at least two stages that are different in its polymer composition. The multistage polymer comprises between <NUM> and <NUM> wt% of monomers comprising an aromatic group.

The multistage polymer is in form of spherical polymer particles. These particles are also called core shell particles or core shell polymers. The first stage forms the core, the second or all following stages the respective shells.

With regard to the spherical polymer particle, it has a weight average particle size between <NUM> and <NUM>. Preferably the weight average particle size of the polymer is between <NUM> and <NUM>, more preferably between <NUM> and <NUM> and advantageously between <NUM> and <NUM>.

The polymer particle has a multilayer structure comprising at least one layer (A) comprising a polymer (A1) having a glass transition temperature below <NUM> and another layer (B) comprising a polymer (B1) having a glass transition temperature over <NUM>. Preferably the polymer (B1) having a glass transition temperature over <NUM> is the external layer of the polymer particle having the multilayer structure.

The polymer particle according to the invention is obtained by a multistage process, such as two or three stages or more stages.

Preferably the polymer (A1) having a glass transition temperature below <NUM> in the layer (A) is made in the first stage of the multistage process forming the core for the polymer particle having the multilayer structure. Preferably the polymer (A1) is having a glass transition temperature below -<NUM>, more preferably below -<NUM>, advantageously below -<NUM>.

Preferably the polymer (B1) having a glass transition temperature over <NUM> is made in the last stage of the multistage process forming the external layer of the polymer particle having the multilayer structure.

There could be additional intermediate layer or layers obtained by an intermediate stage or intermediate stages.

The glass transition temperature Tg of the multistage polymer can be estimated for example by dynamic methods as thermo mechanical analysis.

The polymer (A1) and the layer (A) comprises from 0wt% to less than 50wt% of monomers with aromatic groups. The polymer (B1) and the layer (B) from 0wt% to less than 50wt% of monomers with aromatic groups.

In one embodiment the polymer (B1) and the layer (B) comprises no monomers with aromatic groups.

With regard to the polymer (A1) having a glass transition temperature below <NUM>, it comprises at least 50wt% of polymeric units coming from isoprene or butadiene and the stage (A) is the most inner layer of the polymer particle having the multilayer structure. In other words the stage (A) comprising the polymer (A1) is the core of the polymer particle.

By way of example, the polymer (A1) of the core mention may be made of isoprene homopolymers or butadiene homopolymers, isoprene-butadiene copolymers, copolymers of isoprene with at most 98wt% of another vinyl monomer or monomers and copolymers of butadiene with at most <NUM> wt% of another vinyl monomer or monomers. The vinyl monomer may be styrene, an alkylstyrene, acrylonitrile, an alkyl (meth)acrylate, or butadiene or isoprene or mixtures thereof as long as the polymer (A1) comprises less than 50wt% of monomers with aromatic groups.

The polymer (A1) can be crosslinked. Cross-linking monomers or agents useful in the present invention include, but are not limited to aromatic polyfunctional vinyl compounds such as divinylbenzene and divinyltoluene, polyhydric alcohols such as ethylene glycol dimethacrylate and <NUM>,<NUM>-butanediol diacrylate, trimethacrylates, triacrylates, allyl carboxylates such as allyl acrylate and allyl methacrylate, and di and tri-allyl compounds such as diallyl phthalate, diallyl sebacate, and triallyltriazine.

In one embodiment the core made of polymer (A1) is a butadiene homopolymer.

In another embodiment the core made of polymer (A1) is a butadiene-styrene copolymer.

In one preferably embodiment the polymer (A1) comprises no styrene or other aromatic monomer latter excluding the crosslinking agents.

More preferably the glass transition temperature Tg of the polymer (A1) comprising at least 50wt% of polymeric units coming from isoprene or butadiene is between -<NUM> and <NUM>, even more preferably between -<NUM> and <NUM> and advantageously between -<NUM> and -<NUM>.

With regard to the polymer (B1), mention may be made of homopolymers and copolymers comprising monomers with double bonds and/or vinyl monomers. Preferably the polymer (B1) is a (meth) acrylic polymer.

Preferably the polymer (B1) comprises at least 70wt% monomers chosen from C1 to C12 alkyl (meth)acrylates. Still more preferably the polymer (B1) comprises at least <NUM> wt% of monomers C1 to C4 alkyl methacrylate and/or C1 to C8 alkyl acrylate monomers.

Most preferably the acrylic or methacrylic monomers of the polymer (B1) are chosen from methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and mixtures thereof, as long as polymer (B1) is having a glass transition temperature of at least <NUM>.

The polymer (B1) can comprise functional monomers chosen from glycidyl (meth)acrylate, acrylic or methacrylic acid, the amides derived from these acids, such as, for example, dimethylacrylamide, <NUM>-methoxyethyl acrylate or methacrylate, <NUM>-aminoethyl acrylates or methacrylates and mixtures thereof.

The polymer (B1) can be crosslinked. Cross-linking monomers or agents useful in the present invention include, but are not limited to aromatic polyfunctional vinyl compounds such as divinylbenzene and divinyltoluene, polyhydric alcohols such as ethylene glycol dimethacrylate and <NUM>,<NUM>-butanediol diacrylate, trimethacrylates, triacrylates, allyl carboxylates such as allyl acrylate and allyl methacrylate, and di and tri-allyl compounds such as diallyl phthalate, diallyl sebacate, and triallyltriazine.

Advantageously the polymer (B1) comprises at least 70wt% of monomer units coming from methyl methacrylate.

In one preferred embodiment the polymer (B1) comprises no styrene or other aromatic monomer latter excluding the crosslinking agents.

Preferably the glass transition temperature Tg of the polymer (B1) is between <NUM> and <NUM>. The glass transition temperature of the polymer (B1) is more preferably between <NUM> and <NUM>, advantageously between <NUM> and <NUM> and more advantageously between <NUM> and <NUM>.

Preferably the polymer (B1) is grafted on the polymer made in the previous stage.

In certain embodiments the polymer (B1) is crosslinked.

The multistage polymer in the composition according to the invention is obtained by a multistage process comprising at least two stages. Such a process is for example described in the documents <CIT> or <CIT>.

Preferably the polymer (A1) having a glass transition temperature below <NUM> made during the stage (A), is the first stage of the multistage process.

Preferably the polymer (B1) having a glass transition temperature over <NUM> made during the stage (B) is made after the stage (A) of the multistage process.

More preferably the polymer (B1) having a glass transition temperature over <NUM> made during the stage (B) is the external layer of the polymer particle having the multilayer structure.

There could be additional intermediate stages between stage (A) and stage (B).

In order to obtain a sample of the respective polymers (A1) and (B1) they can be prepared alone, and not by a multistage process, for estimating and measuring more easily the glass transition temperature Tg individually of the respective polymers of the respective stages.

The weight ratio rb of the polymer (A1) of the layer comprised in stage (A) in relation to the complete multi stage polymer is at least 60wt%, preferably at least 70wt%, more preferably at least 75wt%.

The weight ratio rb of the polymer (B1) of the external layer comprised in stage (B) in relation to the complete multi stage polymer is at least 5wt%, preferably at least 6wt%, more preferably at least 7wt%.

According to the invention the ratio rb of the external stage (B) comprising polymer (B1) in relation to the complete multi stage polymer is at most 30w%.

Preferably the ratio of polymer (B1) in view of the complete multi stage polymer is between 5wt% and 30wt%.

A further aspect of the present invention is the use of a multistage polymer as described above as an impact modifier for a transparent polyamide.

With regard to the polyamide polymer composition according to the invention, it comprises.

characterized that the composition fulfills the following formula <MAT> wherein k represents the ratio in mol% of aromatic groups in the polyamide PA, l represents the ratio in mol% of aromatic groups in the multistage polymer and the parameter t is at most <NUM>.

Preferably t is at most <NUM> and advantageously at most <NUM>.

The polyamide polymer composition according to the invention comprises between 1wt% and 80wt%, preferably between 2wt% and 70wt%, more preferably between 3wt% and 50wt%, advantageously between 3wt% and 30wt% and more advantageously between 3wt% and 25wt% of the multistage polymer.

The transparent polyamide is chosen in accordance with the formula (<NUM>), or formula (<NUM>) and/or formula (3b), or formula (<NUM>).

Preferably the polyamide polymer composition according to the invention comprises.

The multistage polymer comprising one stage (A) comprising a polymer (A1) having a glass transition temperature of less than <NUM> and one stage (B) comprising a polymer (B1) having a glass transition temperature of at least <NUM> is obtained by a multistage process.

The preferred and advantageously variants of the multistage polymer and the method for manufacturing the polymer obtained by the multistage process are the same as defined before.

The respective stages (A) and (B) comprising the polymers (A1) and (B1) respectively are the same as defined before.

The polyamide polymer composition according to the invention has a notched impact strength according to Charpy at <NUM> of at least 30kJ/m<NUM>, preferably at least 40kJ/m<NUM> and more preferably at least 50kJ/m<NUM>.

The polyamide polymer composition according to the invention has a light transmission at <NUM> for a sheet of <NUM> thickness of at least <NUM>%, preferably at least <NUM>% and more preferably at least <NUM>%.

The polyamide polymer composition according to the invention has a haze for a sheet of <NUM> thickness of at most <NUM>%, preferably at most <NUM>% and more preferably at most <NUM>%.

Another aspect of the present invention is a method for manufacturing a polymer composition comprising the step of blending a transparent polyamide PA and a multistage polymer in form of core shell particles characterized that the composition fulfils the following formula <MAT> wherein k represents the ratio in mol% of aromatic groups in the polyamide PA, l represents the ratio in mol% of aromatic groups in the multistage polymer and the parameter t is at most <NUM>.

The polymer composition manufactured according to the method of the invention comprises between 1wt% and 80wt%, preferably between 2wt% and 70wt%, more preferably between 3wt% and 50wt%, advantageously between 3wt% and 30wt% and more advantageously between 3wt% and 25wt% of the multistage polymer obtained by the multistage process.

The polyamide polymer compositions according to the invention are not restricted. Rather all current additives for polyamide compositions can be added. Preferably, the additives are selected from the group consisting of inorganic and organic stabilisers, in particular antioxidants, antiozonants, light protection agents, UV stabilisers, UV absorbers or UV blockers, lubricants, colorants, marking agents, pigments, carbon black, graphite, titanium dioxide, zinc sulphide, zinc oxide, barium sulphate, carbon fibers, glass fibers, glass beads, carbon nanotubes, photochromic agents, antistatic agents, mould-release agents, optical brighteners, halogen-containing flame retardants, halogen-free flame retardants, natural layer silicates, synthetic layer silicates and mixtures thereof.

A further aspect of the present invention is the use of the polyamide polymer composition for producing transparent articles.

A still further aspect of the present invention is the use of the polyamide polymer composition for injection impact modified moulding compounds.

An additional aspect of the present invention is a transparent article with at least one region or one layer composed of a polyamide polymer composition as described above. This is particularly preferably a moulding, a foil, a profile, a tube, a hollow body, or an optically variable filter, or an optical lens, preferably an ophthalmic lens, particularly preferably an element with spectral filter effect, e. in the form of spectacle lens, sun lens, corrective lens, optical filter, inspection glasses, sport goggles or ski goggles, visor, safety spectacles, photo-recording, throughflow meters, bursting discs, display, optical data storage, housing or housing parts, especially for shaving apparatus, depilating appliances, measuring devices, or window in buildings or in vehicles, or is a decorative element or a structural element, e. in the form of a spectacle frame or spectacles earpieces, toy, or in the form of part of a sports shoe, or golf equipment especially a golf ball, or cover, in particular in the form of a mobile-telephone casing, a part of electronic equipment, memory media, infrared keys, transportable playback devices, personal digital assistants, smartphones, a coating, in particular of packaging, of decorative items, or of sports equipment, or cladding, preferably in the automobile sector.

The article can have a color, in particular a color gradient, an antireflective coating, a scratch-resistant coating, an optical-filter coating, a polarizing coating, an oxygen-barrier coating, or a combination of these coatings.

The present invention also provides a process for preparation of a polyamide polymer composition as described above. The process is in particular one which comprises mixing the homopolyamide and/or copolyamide in the form of pellets, and also the multistage polymer in the form of powder, granules, compacted powder or masterbatch and moulding them in an extruder with melt temperatures in the range from <NUM> to <NUM> to give an extrudate and chopping with suitable pelletizers to give pellets, preferably using a melt filter on the extruder to remove contamination from moulding compositions for transparent mouldings, suitable melt filters being those that can be constructed from sieves in sheet form or in the form of candle filters, with the possibility, during the compounding process, of adding additives which are desirable for modification of the moulding composition, e. processing stabilizers, color pigments, UV absorbers, heat stabilizers, flame retardants, other transparent polyamides.

The present invention also provides a process for preparation of a polyamide polymer composition as described above.

For the production of the polyamide moulding compound, the components are mixed on normal compounding machines, such as e.g. single- or twin-screw extruders or screw kneaders. The components are thereby metered individually into the feed or supplied in the form of a dry blend. The process is in particular one which comprises mixing the homopolyamide and/or copolyamide in the form of pellets, and also the multistage polymer in the form of powder, granules, compacted powder or masterbatch.

The additives can be used directly or in the form of a masterbatch. The carrier material of the masterbatch concerns preferably a polyolefin or a polyamide. Amongst the polyamides, there are suitable in particular PA <NUM>, PA <NUM>, PA11, or polyamide or copolyamide described in the present invention.

For the dry blend production, the dried granulates and/or possibly further additives are mixed together. This mixture is homogenised by means of a tumble mixer, drum hoop mixer or tumble drier for <NUM>-<NUM> minutes. In order to avoid absorption of moisture, this can be realized under dried protective gas.

The compounding is realized at set cylinder temperatures of <NUM> to <NUM> on a twin-screw extruder COPERION ZSK <NUM> MC. In front of the nozzle, a vacuum could be applied or degassing can take place at atmosphere. The melt is extruded, cooled and chopped with suitable pelletizers, preferably using a melt filter on the extruder to remove contamination from moulding compositions for transparent mouldings, suitable melt filters being those that can be constructed from sieves in sheet form or in the form of candle filters. The granulate is dried for <NUM>-<NUM> hours at <NUM> to <NUM> under nitrogen or in a vacuum to reach a water content of below <NUM> percent by weight.

The present invention further provides a process for production of an article as described above, which comprises moulding a polyamide moulding composition as described above in an extrusion process, in an injection blow-molding process, in an injection-molding process, or in an in-mold-coating process, to give the article.

The tests samples, from polyamide polymer composition described in the present invention, were produced on an injection moulding machine ENGEL VC <NUM>/<NUM> TECH. Cylinders temperatures of <NUM> to <NUM> were used. The mould temperature was <NUM>. In the case of plates used for the measurement of the light transmission and of the haze, a polished mold was used.

The glass transition temperature Tg of polyamide were measured on pellets by using a TA Q2000 apparatus, according to the ISO <NUM>-<NUM>/<NUM> standard at a heating rate of <NUM>/min.

The glass transitions (Tg) of the multistage polymers is measured with equipment able to realize a thermo mechanical analysis. A RDAII "RHEOMETRICS DYNAMIC ANALYSER" proposed by the Rheometrics Company has been used. The thermo mechanical analysis measures precisely the visco-elastics changes of a sample in function of the temperature, the strain or the deformation applied. The apparatus records continuously, the sample deformation, keeping the stain fixed, during a controlled program of temperature variation. The results are obtained by drawing, in function of the temperature, the elastic modulus (G'), the loss modulus and the tan delta. The Tg is higher temperature value read in the tan delta curve, when the derived of tan delta is equal to zero.

Tensile modulus of polyamide compositions were measured following the ISO <NUM>-<NUM>/<NUM> standard on ISO test piece : ISO/CD <NUM>, type A1, 170x20/10x4 mm, at a temperature of <NUM>.

Notch impact strength according to Charpy was measured following the ISO <NUM>-<NUM>/<NUM>/*eA standard, on ISO test piece : ISO/CD <NUM>, type B1, 80x10x4 mm, at a temperature of <NUM> and - <NUM>.

Light transmissions were measured on a spectrophotocolorimeter Konica-Minolta CM-3610A, following the standard ASTM D <NUM>/<NUM>, on plates 100x100 mm with a <NUM> thickness, with illuminant D65 at <NUM>. The light transmissions are indicated in % of the irradiated light quantity.

Haze values were measured on a spectrophotocolorimeter Konica-Minolta CM-3610A, following the standard ASTM D <NUM>/<NUM> with CIE standard illuminant Type C, on plates 100x100 mm with a <NUM> thickness. The haze values are indicated in % of the irradiated light quantity.

PA1 is copolyamide PA <NUM>/B. <NUM> based on formula (<NUM>) with molar ratio <NUM>/<NUM> and having a Tg of <NUM>. PA1 contains no aromatic unit.

PA2 is a copolyamide PA <NUM>/B. T having a Tg of <NUM>, based on formula (<NUM>) with molar ratio <NUM>/<NUM>/<NUM>.

The multistage impact modifier (IM) can be synthesized according to <CIT> or <CIT>.

A first multistage impact modifier of the examples <NUM> and <NUM> is made according to the synthesis described in <CIT>. A multistage polymer is synthesized according to example <NUM> of <CIT> as first stage and example <NUM> as second stage, for obtaining a multistage polymer MBS1, comprising no styrene or aromatic monomer unit.

A second multistage impact modifier of the examples is made according to <CIT> for obtaining a multistage polymer MBS2, comprising about 33wt% styrene or aromatic monomer unit.

Comparative example <NUM> is a non impact modified copolyamide PA1.

Example <NUM> is a compound comprising 5wt% of MBS1 in PA1.

Example <NUM> is a compound comprising 10wt% of MBS1 in PA1.

Example <NUM> is a compound comprising 15wt% of MBS1 in PA1.

Comparative example <NUM> is a non impact modified copolyamide PA2.

Example <NUM> is a compound comprising 5wt% of MBS2 in PA2.

Example <NUM> is a compound comprising 10wt% of MBS2 in PA2.

Example <NUM> is a compound comprising 15wt% of MBS2 in PA2.

The impact resistance of examples <NUM>, <NUM> and <NUM> according to the invention is increased considerably, while the decrease of the modulus, light transmission and haze is acceptable.

Claim 1:
Polyamide polymer composition comprising
a) a transparent polyamide PA and
b) a multistage polymer in form of core shell particles
characterized that the composition fulfils the following formula <MAT> wherein k represents the ratio in mol% of aromatic groups in the polyamide PA, l represents the ratio in mol% of aromatic monomers in the multistage polymer and the parameter t is at most <NUM>
and characterized that the polyamide is amorphous or microcrystalline and the polyamide is transparent by having light transmission of a sheet of <NUM> thickness that is least <NUM>% measured at <NUM> (ISO <NUM>-<NUM>/<NUM>).