WO2005103145A1

WO2005103145A1 - Hybrid transparent polyamide/polyacryl materials exhibiting thermomechanical performances and improved chemical resistance

Info

Publication number: WO2005103145A1
Application number: PCT/FR2005/000862
Authority: WO
Inventors: Ludwik Leibler; Ilias Iliopoulos; Mathilde Freluche; Jean-Jacques Flat; Anthony Bonnet
Original assignee: Arkema France; Centre National De La Recherche Scientifique (Cnrs)
Priority date: 2004-04-09
Filing date: 2005-04-08
Publication date: 2005-11-03
Also published as: FR2868785A1; FR2868785B1

Abstract

The invention relates to a material obtainable by reacting a functional PMMA carrier comprising a carrier group of at least one acid, acid salt, anhydride or epoxy function with a polyamide ended by a primary amine or acid function whose mean molecular mass value ranges from 1000 to 10000 g/mol. The inventive material exhibits an excellent transparency, high thermomechanical performances and chemical resistance.

Description

TRANSPARENT POLYAMIDE / POLYACRYLIC HYBRID MATERIALS WITH THERMOMECHANICAL PERFORMANCE AND IMPROVED CHEMICAL RESISTANCE

The present invention relates to graft copolymer consisting of a PMMA trunk and polyamide grafts of lower average molecular weight of between 1000 and 10,000 g / mol. This graft copolymer is obtained by the reaction of a functional PMMA with a low-mass polyamide with amino or acid termination. A material is obtained which has good transparency as well as good thermomechanical properties and good chemical resistance.

Polymethyl methacrylate (PMMA) is a material appreciated for its excellent optical properties. It is however limited in terms of thermomechanical behavior because its glass transition temperature (denoted T _g ) is 105 ° C. (for a PMMA obtained by radical polymerization). It is also limited in terms of resistance to stress cracking. Research has found a number of solutions to improve this performance. Thus, the copolymerization of methyl methacrylate (MAM) with methacrylic acid (AMA) can give copolymers having higher thermomechanical strengths, it is for example the grade Oroglas HT121 of the applicant. One can also cite the process of imidization of PMMA by reactive extrusion with an amine to give the materials known under the name KAMAX® of the company Rohm and Haas. However, these solutions have limitations which exclude these methacrylic materials from particularly demanding applications from a chemical and / or thermal point of view.

The Applicant has found that a material comprising a graft copolymer consisting of a PMMA trunk and polyamide grafts of number average molecular weight between 1000 and 10,000 g / mol has good transparency and good thermomechanical and chemical resistance.

[Prior art] EP 0 500 361 A2 describes the PMMA / PA alloys produced using a graft copolymer obtained by reaction in the molten state of a PMMA carrying glutaric anhydride functions and of a polyamide terminated by an amine function as compatibilizer of a mixture PMMA and PA. The graft copolymer can be prepared in situ during the manufacture of the alloy.

EP 0 438 239 A2 describes the use as a compatibilizing agent of a graft copolymer obtained by reaction in the molten state of a PMMA carrying glutaric anhydride functions and of a polyamide.

EP 0 537 767 A1 describes a material obtained by the reaction of a PMMA carrying glutaric anhydride functions, a thermoplastic resin which may be a polyamide and a copolymer carrying epoxy functions.

None of these documents mentions the advantage of using a polyamide of number average molecular mass of between 1000 and 10,000 g / mol to obtain a new material having both transparency and thermomechanical and chemical resistance.

[Brief description of the invention]

A first subject of the invention relates to a graft copolymer consisting of a trunk mainly comprising MAM and polyamide grafts which have a number average molecular weight of between 1000 and 10,000 g / mol.

Another subject of the invention relates to the process for preparing the graft copolymer which consists in reacting a functional PMMA comprising at least one group carrying at least one acid, acid salt, anhydride or epoxide function, with a polyamide terminated by a primary or acidic amino function, of number-average molecular mass between 1000 and 10000 g / mol. Preferably, the functional PMMA comprises at least one group carrying at least one acid and / or anhydride function.

Another subject of the invention relates to a material comprising the graft copolymer according to the invention.

[Figures]

Figures 1a, 1b and 1c are TEM microscopy pictures of the sample E2 obtained from a polyamide terminated by a primary amine function -NH ₂ of average molecular mass in number 2500 g / mol.

Figures 2a, 2b and 2c are TEM microscopy pictures of the comparative sample CE9 obtained from a polyamide terminated by a primary amine function -NH of average molecular mass in number 15000 g / mol.

[Detailed description]

As regards functional PMMA, this is a copolymer of MMA comprising by weight from 0.5 to 30%, advantageously from 0.5 to 20%, preferably from 0.5 to 10%, even more preferably from 0 , 5 to 5%, of at least one group carrying at least one acid function, acid salt, anhydride or epoxide.

The functional PMMA may also optionally comprise a comonomer A having at least one double bond C = C, copolymerizable with MAM and which does not carry an acid, anhydride or epoxide function. The comonomer which can be copolymerized with MMA is chosen, for example, from the following monomers: • acrylic monomers of formula CH2 = CH-C (= 0) -O-Rι where Ri denotes an alkyl group in linear, cyclic or branched CrC ₄₀ optionally substituted by a halogen atom, a hydroxy, alkoxy or cyano group, such as for example methylacrylate, ethyl, propyl, n-butyl, isobutyl, tert-butyl, 2-ethylhexyl, hydroxyalkyl acrylates, acrylonitrile; • methacrylic monomers of formula

where R ₂ denotes a linear, cyclic or branched C ₂ -C ₄ o alkyl group optionally substituted by a halogen atom, a hydroxy, alkoxy, cyano, amino or epoxy group such as, for example, ethyl methacrylate, propyl, n-butyl, isobutyl, tert-butyl, 2-ethylhexyl, hydroxyalkyl methacrylates, methacrylonitrile; • vinyl aromatic monomers such as, for example, styrene, substituted styrenes such as alpha-methylstyrene, monochlorostyrene, tert-butyl styrene.

Advantageously, the comonomer A contains only one double bond C = C. Preferably, the comonomer A is an acrylic monomer CH ₂ = CH- C (= O) -O-Rι in which Ri is a C ₁ -C ₈ alkyl such as, for example, methyl, ethyl or propyl acrylate, butyl, 2-ethyl hexyl or a methacrylic monomer CH ₂ = C (CH3) -C (= O) -O-R2 in which R ₂ is a C ₂ -C ₈ alkyl such as ethyl methacrylate , propyl, butyl, 2-ethyl hexyl.

The functional PMMA comprises: • from 70 to 99.5% of MAM, • from 0 to 20% of a comonomer A having at least one double bond C = C, copolymerizable with MAM and which does not carry an acid, anhydride or epoxide function, • from 0.5 to 30% of at least one group carrying at least one acid, acid salt, anhydride or epoxide function.

Advantageously, it includes: • 80 to 99.5% of MAM, • from 0 to 10% of a comonomer A having at least one double bond C = C, copolymerizable with MAM and which does not carry an acid, anhydride or epoxide function, • from 0.5 to 20% at least one group carrying at least one acid, acid salt, anhydride or epoxide function.

Preferably, it comprises: • from 90 to 99.5% of MAM, • from 0 to 5% of a comonomer A having at least one double bond C = C, copolymerizable with MAM and which is not a carrier of 'an acid, anhydride or epoxide function, • from 0.5 to 10% of at least one group carrying at least one acid, acid salt, anhydride or epoxide function.

The group carrying at least one acid, acid salt, anhydride or epoxide function can be: • a monomer comprising a double bond C = C, copolymerizable with MAM and carrying at least one acid function, salt of acid, anhydride or epoxide; and / or • a glutaric anhydride group of formula:

in which R ₃ and R ₄ denote H or a methyl radical.

In the case where the group is a monomer comprising a double bond C = C, copolymerizable with MAM and carrying at least one acid, acid salt, anhydride or epoxide function, the latter copolymerizes with MAM by a mechanism radical. By way of example of a monomer carrying at least one acid function, mention may be made of 2-acrylamido-2-methylpropane sulfonic acid, vinyl sulfonic acid, styrene sulfonic acid, 1-allyloxy acid 2-hydroxypropane sulfonic, alkyl allyl sulfosuccinic acid, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid.

Preferably, it is acrylic acid or methacrylic acid because these two monomers copolymerize very well with MMA. Methacrylic acid is most particularly preferred. In fact, when the copolymerization is carried out in an aqueous dispersed medium, the acrylic acid remains largely dissolved in water, which is not the case with methacrylic acid. The groups carrying an acid function are then the following:

^< Λ ΛΛ (H -

OH OH From an acid function, the acid salt function can be obtained by known techniques. A monomer carrying at least one acid salt function is therefore derived from a monomer carrying at least one acid function by a neutralization reaction. A monomer carrying at least one acid salt function is derived from a monomer carrying at least one acid function from the preceding list. The cation of the acid salt can be for example Li ⁺ , Na ⁺ , K ⁺ , a quaternary ammonium salt.

By way of example of a monomer carrying at least one anhydride function, mention may be made of maleic anhydride, itaconic anhydride, citraconic anhydride.

By way of example of a monomer carrying at least one epoxide function, mention may be made of aliphatic glycidyl esters or aliphatic glycidyl ethers such as allyl glycidyl ether, vinyl glycidyl ether, glycidyl maleate and itaconate, acrylate and glycidyl methacrylate, esters of alicyclic glycidyl or alicyclic glycidyl ethers such as 2-cyclohexene-1-glycidylether, cyclohexene-4,5-diglycidylcarboxylate, cyclohexene-4-glycidyl carboxylate, 5-norbornene-2-methyl-2-glycidyl carboxylate and rendocis-bicyclo (2,2,1) -5-heptene-2,3-diglycidyl dicarboxylate. Glycidyl methacrylate is a preferred monomer because, like MAM, it is a methacrylic ester and therefore it effectively copolymerizes with MAM.

The functional PMMA is obtained by the copolymerization of MAM with at least one monomer carrying at least one acid function, acid salt, anhydride or epoxide, optionally in the presence of a comonomer A having at least one double bond C = C , copolymerizable with MAM and which does not carry an acid, anhydride or epoxy function. The copolymerization can take place in bulk, in solution in a solvent, or else in a dispersed medium (suspension, emulsion, microemulsion). The copolymerization is initiated using one or more radical initiator (s) known to those skilled in the art chosen from diacyl peroxides, peroxyesters, dialkyl peroxides, peroxyacetals, azo compounds. Radical initiators which may be suitable are for example isopropyl carbonate, benzoyl, lauroyie, caproyie, dicumyl peroxide, tert-butyl perbenzoate, tert-butyl 2-ethyl perhexanoate, cumyl hydroperoxide, 1, 1-di (tert-butylperoxy) -3,3,5- trimethylcyclohexane, tert-butyl peroxyisobutyrate, tert-butyl peracetate, tert-butyl perpivalate, amyl perpivalate, tert-butyl peroctoate, azodiisobutyronitrile, azodiisobutyramide, 2,2'-azo-bis (2,4-dimethylvaleronitrile), 4,4'-azo-bis (4-cyanopentanoic). It would not be departing from the scope of the invention to use a mixture of radical initiators chosen from the list above The preferred radical initiator is azodiisobutyronitrile. The functional PMMA can also include glutaric anhydride groups represented by the formula:

in which R ₃ and R denote H or a methyl radical. These are obtained by an intramolecular reaction between two joined functions, for example between two acid functions, between an acid function and an ester function or between two ester functions. This type of group is particularly appreciated because of their high reactivity with respect to the primary amine functions of the polyamide.

When the functional PMMA comprising glutaric anhydride groups is prepared from acrylic or methacrylic acid, the transformation of the acid functions into glutaric anhydride functions is often incomplete. The functional PMMA therefore comprises both glutaric anhydride groups and acrylic or methacrylic acid groups (which have not reacted to give glutaric anhydride functions). This type of functional PMMA is very particularly preferred since the glutaric anhydride groups are very reactive, especially with the primary amine functions. In addition, glutaric anhydride groups are more easily introduced into functional PMMA than by direct copolymerization of MMA with maleic anhydride or with another monomer carrying an anhydride group.

The relative proportion of the acid functions and of the glutaric anhydride functions depends on the content of initial acid functions and on the conditions of the dehydration (temperature, reaction time, pressure, presence or absence of a catalyst, etc.). The overall content of the acid functions and of the glutaric anhydride functions is between 0.5 and 30%, advantageously between 0.5 and 20%, preferably between 0.5 and 10%, even more preferably between 0.5 and 5% . The relative proportion (by weight) of glutaric anhydride functions relative to the glutaric anhydride functions and the acid functions (that is to say the percentage by weight of the glutaric anhydride functions / (glutaric anhydride functions + acid functions)) is between 1 and 100%, preferably between 10 and 90%.

To obtain a functional PMMA carrying glutaric anhydride groups, one of the methods described in documents EP 0318197 B1, Japanese Kokai 60/231756, Japanese Kokai 61/254608 or Japanese Kokai 61/43604, GB can be used. 1437176, US 4789709. According to the method described in EP 0 318 197, a homopolymer or copolymer PMMA is reacted with a secondary amine. The reaction allowing the glutaric anhydride groups to be obtained is carried out at a temperature above 150 ° C, preferably between 200 and 280 ° C, optionally in the presence of a reduced pressure of less than 1 bar and optionally in the presence of a catalyst. acidic or basic. It can be carried out in an extruder having a degassing well or else in a devolatilizer.

The weight average molecular weight (M _w ) of functional PMMA is generally between 10,000 and 500,000 g / mol. Preferably, M _w is between 50,000 and 200,000 g / mol because on the one hand the very low masses are likely to affect the glass transition temperature (T _g ) of the polymer while the very high masses affect its fluidity and makes its transformation in the difficult molten state. A person skilled in the art knows how to adjust the average molecular weight by weight, for example by introducing a transfer agent and / or using the polymerization temperature parameter.

As regards the polyamide, this can be a homopolyamide or a copolyamide terminated by a primary amino function or an acid function. Preferably, it is a primary amino function, which has good reactivity towards acid functions, acid salts, anhydride or epoxide. The primary amine function is very reactive with respect to the acid or anhydride functions.

Advantageously, in order to provide thermomechanical resistance to the material according to the invention, the polyamide has a melting temperature between 100 and 300 ° C, preferably between 140 and 250 ° C

Homopolyamide is understood to mean the condensation products of a lactam (or of the corresponding amino acid) or of a diacid with a diamine (or their salts). The chain limiter, which may be a diacid, a monoacid, a diamine or a monoamine in the case of lactams, and another diacid or another diamine in the case of polyamides resulting from the condensation of a diamine with a diacid. The term “copolyamide” is understood to mean the preceding ones in which there is at least one more monomer than necessary, for example two lactams or a diamine and two acids or else a diamine, a diacid and a lactam.

The polyamide is chosen from PA 6, PA 6-6, PA 11, PA 12 and their co-polymers. Preferably, it is PA 6 because this polyamide provides good resistance to the solvent by its crystallinity as well as good thermomechanical resistance.

According to a first type, the copolyamide results from the condensation of at least two alpha-omega aminocarboxylic acids or of at least two lactams having 6 to 12 carbon atoms or of a lactam and an aminocarboxylic acid not having the same number of carbon atoms. The copolyamide of this first type can also comprise units which are residues of diamines and dicarboxylic acids. As an example of a dicarboxylic acid, mention may be made of diacids such as isophthalic, terephthalic, adipic, azelaic, suberic, sebacic, nonanedioic acid and dodecanedioic acid.

As an example of a diamine, mention may be made of hexamethylene diamine, dodecamethylenediamine, metaxylylenediamine, bis-p aminocyclohexylmethane and trimethylhexamethylene diamine.

By way of example of alpha-omega aminocarboxylic acid, mention may be made of aminocaproic acid, aminoundecanoic acid and aminododecanoic acid.

By way of example of lactam, mention may be made of caprolactam, oenantholactam and laurolactam.

According to a second type, the copolyamide results from the condensation of at least one alpha-omega aminocarboxylic acid (or a lactam), at least one diamine and at least one dicarboxylic acid. The alpha-omega aminocarboxylic acid, the lactam and the dicarboxylic acid can be chosen from those mentioned above. The diamine can be a branched aliphatic diamine, linear or cyclic or even aryl. Examples include hexamethylenediamine, piperazine, isophorone diamine (IPD), methyl pentamethylenediamine (MPDM), bis (aminocyclohexyl) methane (BACM), bis (3-methyl-4 aminocyclohexyl) methane (BMACM).

So that the polyamide ends with a primary amine function, a chain limiter of the formula: R ₅ - NH can be used

R ₆ in which R ₅ is hydrogen or a linear or branched alkyl group containing up to 20 carbon atoms, Rβ is a group having up to 20 linear or branched alkyl or alkenyl carbon atoms, a limiting cycloaliphatic radical can for example be laurylamine or oleylamine. The polyamide terminated with a primary or acidic amine function has a number average molecular mass (M _n ) of between 1000 and 10,000 g / mol, rather between 1000 and 7000 g / mol, advantageously between 1000 and 5000 g / mol, preferably between 1000 and 3000 g / mol. This average molecular weight is determined using steric exclusion chromatography calibrated using PMMA samples. M _n is therefore given in PMMA equivalents.

The preferred monofunctional polymerization limiters are laurylamine and oleylamine. The polyamides can be manufactured according to methods known to those skilled in the art, for example by autoclave polycondensation. The polycondensation is carried out at a temperature generally between 200 and 300 ° C., under vacuum or under an inert atmosphere, with stirring of the reaction mixture. The average chain length of the polyamide is determined by the initial molar ratio between the polycondensable monomer or the lactam and the chain limiter. For the calculation of the average chain length, there is usually one chain limiter molecule for an oligomer chain.

Graft copolymer

The graft copolymer according to the invention is obtained by the reaction of functional PMMA and of polyamide terminated with a primary or acidic amine function. If the polyamide is terminated with a primary amine function, the functional PMMA preferably carries acid, acid salt, anhydride or epoxide functions. If the polyamide is terminated with an acid function, the functional PMMA preferably carries epoxy functions.

During the reaction of the functional PMMA and the polyamide terminated with a primary or acidic amine function, a graft copolymer is formed, noted PMMA (g) PA, consisting of a trunk which comes from functional PMMA and polyamide grafts (for more details on the grafted copolymers, one can refer to Kirk-Othmer, Encyclopaedia of Chemical Technology, 3 ^rd edition, Volume 6, page 798). The grafted copolymer therefore consists of a trunk mainly comprising MAM and polyamide grafts which have a number average molecular weight of between 1000 and 10,000 g / mol. The trunk comprises from 70 to 99.5%, advantageously from 80 to 99.5%, preferably from 90 to 99.5%, of MAM.

Depending on the nature of the functional PMMA, the quantities of functional PMMA and of polyamide which are introduced as well as the reaction conditions, it is possible to obtain a graft copolymer more or less rich in grafts. On average, there are for a trunk from 1 to 100, preferably from 1 to 50, polyamide grafts.

The reaction can be carried out in solution in a solvent or else in the molten state. Preferably, the reaction is carried out in the molten state since this makes it possible to avoid the use of solvent which must then be eliminated once the reaction is complete. The molten state also makes it possible to accelerate the speed of the reaction. Any mixing tool suitable for thermoplastics can be used. A twin-screw extruder, in particular a corotative twin-screw, is entirely suitable because it allows the mixture to be produced in the molten state, can operate continuously and ensures good homogenization of the functional PMMA and of the polyamide. The reaction is carried out at a temperature between 180 and 320 ° C, preferably between 180 and 280 ° C. The average residence time of the molten material in the extruder can be between 1 second and 15 minutes, rather between 1 second and 10 minutes, preferably between 1 second and 5 minutes. If an extruder is used, granules are collected at the exit of the extruder. These granules can then be put into the desired form (film, injected part, molded part, plate, etc.) using a thermoplastic transformation tool known to those skilled in the art, for example an extruder. For the reaction, from 5 to 90%, rather from 10 to 50%, advantageously from 20 to 40%, of polyamide terminated with a primary amine or acid function is used, for respectively from 10 to 95%, rather from 50 to 90%. , advantageously from 60 to 80%, of functional PMMA. The reaction of 20 to 40% of polyamide terminated by a primary or acidic amine function and from 60 to 80% of functional PMMA makes it possible to obtain a material having good transparency.

Depending on the initial amounts of functional PMMA and polyamide, as well as the reaction conditions (for example contact time, temperature), functional PMMA and / or unreacted polyamide may remain. The reaction therefore leads to a material consisting of: - the PMMA (g) PA graft copolymer; - unreacted functional PMMA; - of polyamide terminated by an unreacted primary amine or acid function.

More specifically, the material consists of: - from 20 to 98% of graft copolymer; - from 1 to 50% of unreacted functional PMMA; - from 1 to 50% of polyamide terminated by an unreacted primary amine or acid function, the total making 100%.

Preferably, the material consists of: - from 20 to 80% of graft copolymer; - from 5 to 50% of unreacted functional PMMA; - from 5 to 50% of polyamide terminated by a primary amine or unreacted acid function, the total making 100%. The presence of functional PMMA and / or unreacted polyamide is not necessarily detrimental to the final properties of the material, it can even improve some of its properties. The functional PMMA which has not reacted has a strong affinity with the backbone of the graft copolymer, the polyamide which has not reacted has a strong affinity with the grafts of the graft copolymer. We can therefore observe a phenomenon of swelling of the trunk and grafts of the grafted copolymer which has already been observed for other types of grafted copolymers (see on this subject the following article: F. Court, Nature Mater. 2002, Vol .1, page 54).

The Applicant has found that when the polyamide has a low number average molecular weight of between 1000 and 10000 g / mol, the grafted copolymer is organized into nanodomains, that is to say into domains whose average size is smaller at 100 nm. This organization makes it possible to obtain a homogeneous material having all of the properties described above.

Impact additives A core-shell impact modifier (more commonly called core-shell) can be added to the material in order to improve its impact resistance. This impact modifier is in the form of fine particles having an elastomer core and at least one thermoplastic shell, the particle size generally being less than μm and advantageously between 50 and 300 nm. The impact modifier is prepared using emulsion polymerization. 0 to 20%, preferably 0 to 10%, of impact modifier of core-shell type relative to the material is added to the material.

The core can consist, for example: • of a homopolymer of isoprene or butadiene or • of copolymers of isoprene with at most 30 mol% of a vinyl monomer or • butadiene copolymers with at most 30 mol% of a vinyl monomer.

The vinyl monomer can be styrene, an alkylstyrene, acrylonitrile or an alkyl (meth) acrylate.

The core can also consist of: • a homopolymer of an alkyl (meth) acrylate or • copolymers of an alkyl (meth) acrylate with at most 30 mol% of a monomer chosen from a other alkyl (meth) acrylate and a vinyl monomer.

The alkyl (meth) acrylate is advantageously butyl acrylate. The vinyl monomer can be styrene, an alkylstyrene, acrylonitrile, butadiene or isoprene.

The heart can be advantageously crosslinked in whole or in part. It suffices to add at least difunctional monomers during the preparation of the core, these monomers can be chosen from poly (meth) acrylic esters of polyols such as butylene di (meth) acrylate and trimethylol propane trimethacrylate. Other difunctional monomers are for example divinylbenzene, trivinylbenzene, vinyl acrylate and vinyl methacrylate. The heart can also be crosslinked by introducing therein, by grafting or as a comonomer during the polymerization, unsaturated functional monomers such as anhydrides of unsaturated carboxylic acids, unsaturated carboxylic acids and unsaturated epoxides. By way of example, mention may be made of maleic anhydride, (meth) acrylic acid and glycidyl methacrylate.

The bark or barks consist of a homopolymer of styrene, of an alkylstyrene or of methyl methacrylate or of copolymers comprising at least 70 mol% of one of these preceding monomers and at least one comonomer chosen from other previous monomers, another alkyl (meth) acrylate, vinyl acetate and acrylonitrile. The bark can be functionalized by introducing therein, by grafting or as a comonomer during the polymerization, unsaturated functional monomers such as anhydrides of unsaturated carboxylic acids, unsaturated carboxylic acids and unsaturated epoxides. By way of example, mention may be made of maleic anhydride, (meth) acrylic acid and glycidyl methacrylate.

By way of example of impact modifier, mention may be made of heart-bark co-polymers having a polystyrene bark and heart-bark co-polymers having a PMMA bark. There are also heart-bark co-polymers with two barks, one made of polystyrene and the other outside of PMMA. Examples of impact modifiers, as well as their preparation process, are described in the following patents: US 4,180,494, US 3,808,180, US 4,096,202, US 4,260,693, US 3,287,443, US 3,657,391, US 4,299,928, US 3,985,704, US 5,773,520.

Advantageously, the heart represents, by weight, 70 to 90% of the impact modifier and the bark from 30 to 10%.

The impact modifier can be of the soft / hard type. As an example of a soft / hard type impact modifier, mention may be made of: (i) from 75 to 80 parts of a core comprising at least 93% of butadiene, 5% of styrene and 0.5 with 1% of divinylbenzene and (ii) from 25 to 20 parts of two barks essentially of the same weight, one inside made of polystyrene and the other outside made of PMMA.

Another example of a soft / hard type impact modifier, that which may be mentioned is that having a core of poly (butyl acrylate) or of a copolymer of butyl acrylate and butadiene and a shell of PMMA.

The impact modifier can also be of the hard / soft / hard type, that is to say it contains in order a hard core, a soft bark and a hard bark. The hard parts can consist of polymers from the bark of soft / hard previous and the soft part can be made of the polymers of the core of the previous soft / hard.

As an example of an impact modifier of the hard / soft / hard type, it can be cited that consisting of: (i) a core made of a copolymer of methyl methacrylate and ethyl acrylate, (ii) a layer made of a copolymer of butyl acrylate and styrene, (iii) of a shell made of a copolymer of methyl methacrylate and ethyl acrylate.

The impact modifier can also be of the hard (heart) / soft / semi-hard type. In this case, the "semi-hard" outer bark consists of two barks: one intermediate and the other outer. The intermediate shell is a copolymer of methyl methacrylate, styrene and at least one monomer chosen from alkyl acrylates, butadiene and isoprene. The outer shell is a homopolymer or copolymer PMMA.

An example of a hard / soft / semi-hard impact modifier is that constituted in this order: (i) of a core made of a copolymer of methyl methacrylate and of ethyl acrylate, (ii) of a shell of a copolymer butyl acrylate and styrene, (iii) a bark in a copolymer of methyl methacrylate, butyl acrylate and styrene, (iv) a bark in a copolymer of methyl methacrylate and l 'ethyl acrylate.

The impact modifier and the material according to the invention are mixed using a mixing tool suitable for thermoplastics, for example an extruder. additives

Other additives can also be added to the material. It can be anti-UV additive (s), antioxidant (s), mold release agent (s), lubricating agent (s), etc. As an example of additives anti-UV, mention may be made of those described in US Pat. No. 5,256,472. Benzotriazoles and benzophenones are advantageously used. By way of example, it is possible to use Tinuvin® 213 or Tinuvin® 109 and preferably Tinuvin® 234 from the company Ciba Specialty Chemicals.

Material Uses

The material according to the invention can be used in the form of films, blown extruded parts, injected parts. It can also be in the form of extruded plates which are used for sanitary applications (manufacture of baths, sinks, shower tubs, ...). In the sanitary field, the chemical resistance and the resistance to cracking of the material are two appreciated properties.

The material according to the invention can also be transformed into organic panes, window frames, pipes, air ducts, seals, etc. In the field of transport for example, it can be used to manufacture decorative panels in automobiles , trucks, trains and planes. In the field of sport, it can be used as parts injected into sports shoes, in golf clubs, ... It can also find applications in fibers for example as coatings for optical fibers, but also in parts for medical use, in the field of electrical and electronic applications, and more generally as technical polymers without excluding applications in packaging.

The material according to the invention can also serve as a compatibilization agent for obtaining an alloy based on a polyamide and on a polymer chosen from PMMA, PVDF, PVC and acrylic polymers. We can for example use a corotative extruder to make the mixture. Preferably, the polymer of the alloy is PMMA or PVDF.

The polyamide can be a PA 6, PA 6-6, PA 11 or PA 12. The polyamide of the alloy is of the same nature as the polyamide terminated by a primary amine or acid function which serves to obtain the grafts. Thus, for example, for the compatibilization of a polyamide 12 with PMMA, the grafts are made of polyamide 12.

PMMA denotes a homo- or copolymer of MAM comprising more than 50% by weight of MAM. In the case where the PMMA is a copolymer, the MMA is copolymerized with at least one comonomer chosen from: • the acrylic monomers of formula CH ₂ = CH-C (= O) -O-Rι where Ri denotes a C alkyl group -ι-C o linear, cyclic or branched optionally substituted by a halogen atom, a hydroxy group, alkoxy, cyano, such as for example methyl acrylate, ethyl, propyl, n-butyl, d isobutyl, tert-butyl, 2-ethylhexyl, hydroxyalkyl acrylates, acrylonitrile; • methacrylic monomers of formula CH ₂ = C (CH ₃ ) -C (= O) -0-R ₂ where R ₂ denotes a linear, cyclic or branched C ₂ -C ₀ alkyl group optionally substituted by an atom of halogen, a hydroxy, alkoxy, cyano, amino or epoxy group such as, for example, ethyl, propyl, n-butyl, isobutyl, tert-butyl or 2-ethylhexyl methacrylate, hydroxyalkyl methacrylates, methacrylonitrile; • vinyl aromatic monomers such as, for example, styrene, substituted styrenes such as alpha-methylstyrene, monochlorostyrene, tert-butyl styrene.

PVDF denotes a homo- or copolymer of vinylidene fluoride (VF ₂ ) comprising more than 50% by weight of VF. In the case where the PVDF is a copolymer, the VF ₂ is copolymerized with at least one chosen comonomer among the compounds containing a vinyl group capable of opening to polymerize and which contains, directly attached to this vinyl group, at least one fluorine atom, a fluoroalkyl group or a fluoroalkoxy group. By way of example of a comonomer, mention may be made of vinyl fluoride; trifluoroethylene; chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro (alkyl vinyl) ethers such as perfluoro (methyl vinyl) ether (PMVE), perfluoro (ethyl vinyl) ether (PEVE) and perfluoro (propyl vinyl) ether (PPVE); perfluoro (1, 3-dioxole); perfluoro (2,2-dimethyl-1,3-dioxole) (PDD); the product of formula CF ₂ = CFOCF2CF (CF ₃ ) OCF ₂ CF2X in which X is S0 ₂ F, CO ₂ H, CH ₂ OH, CH ₂ OCN or CH ₂ OPO ₃ H; the product of formula CF ₂ = CFOCF ₂ CF ₂ SO ₂ F; the formula product

where n is 1, 2, 3, 4 or 5; the product of formula R ₇ CH2θCF = CF2 in which R is hydrogen or F (CF ₂ ) _Z and z is 1, 2, 3 or 4; the product of formula R ₈ OCF = CH ₂ in which R ₈ is F (CF ₂ ) _Z - and z is 1, 2, 3 or 4; perfluorobutyl ethylene (PFBE); 3,3,3-trifluoropropene and 2-trifluoromethyl-3, 3, 3 -trifluoro-1-propene.

The alloy comprises: • from 2 to 20% of the material according to the invention; • from 10 to 90% of a polyamide which can be chosen from PA 6, PA 6- 6, PA 11 or PA 12; • from 10 to 90% of a polymer chosen from PMMA, PVDF, PVC and acrylic polymers.

The material according to the invention can also serve as a coextrusion binder in a multilayer structure based on polyamide and on a polymer chosen from PMMA, PVDF, PVC and acrylic polymers. The multilayer structure is therefore composed in the order of the following layers: - a layer d of polyamide; - a layer c2 of the material according to the invention; a layer c3 of a polymer chosen from PMMA, PVDF, PVC and acrylic polymers; the layers adhering to each other.

The definitions of the terms polyamide, PMMA and PVDF have been given previously.

The multilayer structure may for example be in the form of a film, a plate, a tube or a hollow body. In the case of a multilayer structure in the form of a film, each layer d, c2 and c3 may have a thickness of between 2 and 300 μm, advantageously between 5 and 200 μm, preferably between 10 and 100 μm. In the case of a multilayer structure in the form of a plate, a tube or a hollow body, the layer c2 of the material according to the invention has a thickness of between 2 and 300 μm, preferably between 2 and 100 μm. The other layers d and c3 have a thickness greater than 100 μm, rather between 0.1 and 100 mm.

[Examples]

The following examples illustrate the invention without limiting its scope.

Preparation conditions The materials were prepared by reactive extrusion on a DACA micro-extruder with a capacity of 5 g at 220 ° C. for 10 minutes at a rotational speed of 60 revolutions / minute under a nitrogen atmosphere.

To observe the stability of the products, the samples were subjected to thermal annealing for 20 hours at 225 ° C.

Polymers used

PMMA1: it is a copolymer of MAM and methacrylic acid containing glutaric anhydride groups. The molar proportions are: 92.1% of MMA, 2.2% of methacrylic acid and 5.7% of glutaric anhydride groups. This copolymer has a molecular weight by weight M _w of 84,000 g / mol, a molecular weight by number M _n of 42,000 g / mol. PMMA2: this is OROGLAS HT121, which is a copolymer of MAM and methacrylic acid containing glutaric anhydride groups. The molar proportions are: 95.5% of MMA, 4% of methacrylic acid and 0.5% of glutaric anhydride groups. This copolymer has a molecular weight by weight M _w of 102,000 g / mol, a molecular weight by number M _n of 48,000 g / mol.

PA1: it is a mono-amino PA6 of M _n 2500 g / mol having an amine index of 0.4 meq / g.

PA2: it is a mono-amino PA6 of M _n 6000 g / mol having an amine index of 0.17 meq / g.

PA3: it is a PA6 (Domamid 27 from the company DOMO) of M _n 15,000 g / mol having an amine index of 0.045 meq / g.

characterizations

Thermomechanical behavior: measurement of the elastic modulus (E ') as a function of the temperature in Dynamic Mechanical Analysis (DMA) at a frequency of 1 Hz.

Chemical resistance: the test consists in observing the resistance of a rod placed in chloroform for three days at room temperature (the rod represents 3% by weight relative to chloroform). The appreciation of the resistance is qualitative and consists in seeing if the rod retains its shape or disintegrates in contact with the solvent. If the rod disintegrates, the chemical resistance is very bad (noted ---) while if the rod retains its shape, the chemical resistance is very good (noted ++++). Transparency: transparency is assessed qualitatively and also by measuring the haze according to standard ASTM D1003 on a film 100 μm thick.

Analysis under a microscope: the samples were observed under a transmission microscope (TEM) after cutting the sample at the microtome and treatment with phosphotungstic acid. In these pictures, the polyamide appears in contrast in black.

In the table below, the signs - and + represent a rating scale going from very bad (---) to very good (+++). The percentages are given by weight%.

Results obtained Examples E2 to E7 are according to the invention. Example CE 9 is a comparative example according to the prior art.

It is found that with a polyamide terminated by an amine function of M _n greater than 10,000 g / mol, the resistance to chloroform is less good. In addition, the value of E 'is also reduced compared to the tests in the presence of. lower amine terminated polyamides.

We can also see that the haze is less good for the CE9 example. Figures 1a and 1b correspond to the sample E2 before annealing, Figure 1c corresponds to the sample E2 after annealing. Figures 2a and 2b correspond to the sample CE9 before annealing, Figure 2c corresponds to the sample CE2 after annealing. It is noted that the sample E2 has polyamide domains (in black on the photographs) whose size is less than 100 nm, or even less than 50 nm. The CE9 sample has polyamide domains of larger size, some exceeding 1 μm. This is also visible if we compare Figures 1c and 2c, that is to say for the samples after annealing.

Claims

1. Grafted copolymer consisting of a trunk mainly comprising MAM and polyamide grafts of average molecular weight between 1,000 and 10,000 g / mol, rather between 1,000 and 7,000 g / mol, advantageously between 1,000 and 5,000 g / mol, preferably between 1000 and 3000 g / mol.

2. graft copolymer according to claim 1 wherein the trunk comprises from 70 to 99.5%, advantageously from 80 to 99.5%, preferably from 90 to 99.5% of MMA.

3. graft copolymer according to one of claims 1 or 2 wherein the grafts are in PA 6, PA 6-6, PA 11, PA 12 and their copoiymers.

4. graft copolymer according to claim 3 wherein the polyamide has a melting temperature between 100 and 300 ° C, preferably between 140 and 250 ° C.

5. graft copolymer according to one of the preceding claims, in which there are, on average, from 1 to 100, preferably from 1 to 50, polyamide grafts.

6. Process for the preparation of graft copolymer consisting in reacting a functional PMMA with a polyamide terminated by a primary amine or acid function of number average molecular weight of between 1000 and 10,000 g / mol, rather between 1000 and 7000 g / mol , advantageously between 1000 and 5000 g / mol, preferably between 1000 and 3000 g / mol.

7. The method of claim 6 wherein the functional PMMA is a copolymer of MAM comprising by weight from 0.5 to 30%, advantageously from 0.5 to 20%, preferably 0.5 to 10%, even more preferably 0.5 to 5%, of at least one group carrying at least one acid, acid salt, anhydride or epoxide.

8. The method of claim 6 or 7 wherein the functional PMMA comprises a comonomer A having at least one double bond C = C, copolymerizable with MAM and which does not carry an acid, anhydride or epoxide function

9. The method of claim 8 wherein the comonomer A is chosen for example from the following monomers: • the acrylic monomers of formula CH ₂ = CH-C (= 0) -O-Rι where Ri denotes an alkyl group in CrC ₀ linear, cyclic or branched optionally substituted by a halogen atom, a hydroxy, alkoxy or cyano group; • methacrylic monomers of formula CH2 = C (CH ₃ ) -C (= 0) -0-R ₂ where R ₂ denotes a linear, cyclic or branched C ₂ -C ₄₀ alkyl group optionally substituted by a halogen atom , a hydroxy, alkoxy, cyano, amino or epoxy group; • vinyl aromatic monomers.

10. Method according to one of claims 6 to 9 wherein the functional PMMA comprises: • from 70 to 99.5% of MAM, • from 0 to 20% of a comonomer A having at least one double bond C = C , copolymerizable with MAM and which does not carry an acid, anhydride or epoxide function, • from 0.5 to 30% of at least one group carrying at least one acid function, acid salt, anhydride or epoxide.

11. Method according to one of claims 6 to 10 in which the functional PMMA comprises: • from 80 to 99.5% of MAM, • from 0 to 10% of a comonomer A having at least one double bond C = C, copolymerizable with MAM and which does not carry an acid, anhydride function or epoxide, “from 0.5 to 20% of at least one group carrying at least one acid, acid salt, anhydride or epoxide function.

12. Method according to one of claims 6 to 11 wherein the functional PMMA comprises: • from 90 to 99.5% of MAM, • from 0 to 5% of a comonomer A having at least one double bond C = C , copolymerizable with MAM and which does not carry an acid, anhydride or epoxide function, • from 0.5 to 10% of at least one group carrying at least one acid function, acid salt, anhydride or epoxide.

13. Method according to one of claims 6 to 12 wherein the group carrying at least one acid function, acid salt, anhydride or epoxide is: • a monomer comprising a double bond C = C, copolymerizable with MAM and carrying at least one acid, acid salt, anhydride or epoxide function; and / or • a glutaric anhydride group of formula:

in which R ₃ and R denote H or a methyl radical.

14. The method of claim 13 wherein the functional PMMA comprises glutaric anhydride groups and acrylic or methacrylic acid groups.

15. Method according to one of claims 6 to 14 wherein the polyamide is chosen from PA 6, PA 6-6, PA 11, PA 12 and their co-polymers.

16. The method of claim 15 wherein the polyamide has a melting temperature between 100 and 300 ° C, preferably between 140 and 250 ° C.

17. Material consisting of: - from 20 to 98% of graft copolymer according to one of claims 1 to 5; - from 1 to 50% of unreacted functional PMMA; - from 1 to 50% of polyamide terminated by an unreacted primary amine or acid function, the total making 100%.

18. The material as claimed in claim 17, in which 0 to 20%, preferably 0 to 10%, of impact modifier of core-shell type is added with respect to the material.

19. Use of the material according to one of claims 17 or 18 in the form of films, blown extruded parts, injected parts or extruded plates.

20. Use of the material according to claims 17 or 18 as a compatibilizing agent for obtaining an alloy based on a polyamide and on a polymer chosen from PMMA, PVDF, PVC and acrylic polymers.

21. Use of the material according to claims 17 or 18 as a coextrusion binder of a multi-layer structure based on polyamide and of a polymer chosen from PMMA, PVDF, PVC and acrylic polymers, having the order of the layers following: - a layer d of polyamide; - a layer c2 of the material; a layer c3 of a polymer chosen from PMMA, PVDF, PVC and acrylic polymers; the layers adhering to each other.