EP1470188A1

EP1470188A1 - Antistatic styrenic polymer composition

Info

Publication number: EP1470188A1
Application number: EP02701371A
Authority: EP
Inventors: Martin Baumert; Christophe Lacroix
Original assignee: Atofina SA
Current assignee: LACROIX, CHRISTOPHE; Arkema France SA
Priority date: 2002-01-31
Filing date: 2002-01-31
Publication date: 2004-10-27
Also published as: US20050020772A1; CN1622976A; JP2005517756A; AU2002234708A1; WO2003068860A1; CA2474551A1

Abstract

The invention relates to a composition comprising, for 100 parts by weight, 99-60 parts of a styrenic polymer (A), 1 - 40 parts of (B) + (C), (B) being a polyamide block and polyether block copolymer essentially comprising ethylene oxide patterns (C2H4-O)-, (C) being a compatibilizer chosen from block copolymers comprising at least one polymerized block comprising styrene and at elast one polymerized block comprising methyl methacrylate, (B)/(C) ranging from 2 to10.

Description

ANTISTATIC STYRENIC POLYMER COMPOSITIONS

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The invention relates to antistatic styrene polymer compositions and more specifically a composition comprising a styrene polymer (A), a copolymer (B) with polyamide blocks and polyether blocks essentially comprising ethylene oxide units - (C2H4— O) ~ and a compatibilizer (C).

This is to give the styrene polymer (A) antistatic properties. The formation and retention of static electricity charges on the surface of most plastics is known. The presence of static electricity on thermoplastic films leads for example these films to stick to each other making their separation difficult. The presence of static electricity on packaging films can cause the accumulation of dust on the objects to be packaged and thus hinder their use. Styrene resins such as for example polystyrene or ABS are used to make cases for computers, telephones, televisions, photocopiers as well as many objects. Static electricity causes the accumulation of dust but above all can also damage the microprocessors or the components of the electronic circuits contained in these objects. For these applications, we generally seek compositions based on styrene resin having a surface resistivity measured according to standard IEC93 less than 5.10 ¹³ Ω / D or a volume resistivity measured according to standard IEC93 less than 5.10 ¹⁶ Ω.cm (we choose the type of resistivity depending on the application, it being understood that these two types of resistivity evolve in the same direction anyway). It is indeed considered that such resistivities provide sufficient antistatic properties for certain applications in the field of polymer materials in contact with electronic components.

The prior art has described antistatic agents such as ionic surfactants of the ethoxylated amino or sulfonate type which are added to polymers. However, the antistatic properties of the polymers depend on the ambient humidity and they are not permanent since these agents migrate to the surface of the polymers and disappear. It was then proposed as antistatic agents copolymers with polyamide blocks and hydrophilic polyether blocks, these agents have the advantage of not migrating and therefore to give permanent antistatic properties and more independent of ambient humidity.

Japanese patent application JP 60 170 646 A published on September 4, 1985 describes compositions consisting of 0.01 to 50 parts of polyether block amide and 100 parts of polystyrene, they are useful for making sliding parts and resistant parts to wear. Antistatic properties are not mentioned.

Patent application EP 167 824 published on January 15, 1986 describes compositions similar to the previous ones and according to one form of the invention, the polystyrene can be mixed with a polystyrene functionalized with an unsaturated carboxylic anhydride. These compositions are useful for making injected parts. Antistatic properties are not mentioned.

Japanese patent application JP 60 023 435 A published on February 6

1985 describes antistatic compositions comprising 5 to 80% of polyetheresteramide and 95 to 20% of a thermoplastic resin chosen among others from polystyrene, ABS and PMMA, this resin being functionalized with acrylic acid or maleic anhydride . The amount of polyetheresteramide in the examples is 30% by weight of the compositions. Patent EP 242 158 describes antistatic compositions comprising 1 to 40% of polyetheresteramide and 99 to 60% of a thermoplastic resin chosen from styrene resins, PPO and polycarbonate. According to a preferred form, the compositions also comprise a vinyl polymer functionalized with a carboxylic acid which may for example be a polystyrene modified with methacrylic acid.

International patent application PCT / FR00 / 02140 teaches the use of copolymers of styrene and an unsaturated carboxylic acid anhydride, copolymers of ethylene and an unsaturated carboxylic acid anhydride, copolymers of ethylene and of an unsaturated epoxide, of SBS or SIS block copolymers grafted with a carboxylic acid or an unsaturated carboxylic acid anhydride as compatibilizer between a styrene resin and a copolymer with polyamide blocks and polyether blocks. As documents of the prior art, mention may also be made of: EP 927727, - J. Polym. Sci, Part C: Polym. Lett. (1989), 27 (12), 481

J. Polym. Sci, Part B, Polym. Phys. (1996), 34 (7), 1289 - JAPS, (1995), 58 (4), 753 JP 04370156 JP 04239045 JP 02014232 JP 11060855 JP 11060856 - JP 09249780

JP 08239530 JP08143780 The prior art shows either mixtures (i) of styrene resin and polyetheresteramide without compatibilizer, or mixtures (ii) of polyetheresteramide and functionalized styrene resin or mixtures (iii) of polyetheresteramide, non-styrene resin functionalized and functionalized styrene resin.

The mixtures (i) are antistatic if the polyetheresteramide is well chosen but have poor mechanical properties, in particular the elongation at break is much less than that of styrene resin alone. As for mixtures (ii) and (iii), it is necessary to have a functionalized styrene resin, which is complicated and expensive. The object of the invention is to make the ordinary styrene resins used to make the objects mentioned above antistatic, these resins not being functionalized. It has now been found that by using specific compatibilizers one can obtain styrene resin compositions comprising a styrene resin and a copolymer with polyamide blocks and polyether blocks, having an excellent elongation at break, an excellent stress at break and an excellent impact resistance (notched charpy), compared to the same composition without compatibilizer. The present invention relates to a composition comprising per 100 parts by weight: - 99 to 60 parts by weight of a styrene polymer (A), - 1 to 40 parts by weight of (B) + (C), (B) being a polyamide block and polyether block copolymer essentially comprising ethylene oxide units - (C2H4 - O) -, (C) being a compatibilizer chosen from block copolymers comprising at least one polymerized block comprising styrene and at least one polymerized block comprising methyl methacrylate, the mass ratio (B) / (C) being between 2 and 10.

By way of example of a styrene polymer (A), mention may be made of polystyrene, polystyrene modified with elastomers, random or block copolymers of styrene and dienes such as butadiene, copolymers of styrene and acrylonitrile (SAN), the SAN modified by elastomers in particular ABS which is obtained for example by grafting (graft-polymerization) of styrene and ^" acrylonitrile on a trunk of polybutadiene or butadiene-acrylonitrile copolymer, mixtures of SAN and ABS. The elastomers mentioned above may for example be EPR (abbreviation of ethylene-propylene-rubber or ethylene-propylene elastomer), EPDM (abbreviation of ethylene -propylene-diene rubber or ethylene-propylene-diene elastomer), polybutadipne, acrylonitrile-butadiene copolymer, polyisoprene, isoprene-acrylonitrile copolymer. In particular, A may be an impact polystyrene comprising a polystyrene matrix surrounding rubber nodules generally comprising polybutadiene.

In the polymers (A) which have just been mentioned, part of the styrene can be replaced by unsaturated monomers copolymerizable with styrene, by way of example, we may mention alpha-methylstyrene and (meth) acrylic esters. In this case, A can comprise a styrene copolymer, styrene-alpha-methylstyrene copolymers, styrene-chlorostyrene copolymers, styrene-propylene copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene copolymers which may be mentioned -vinyl chloride, styrene-vinyl acetate copolymers, styrene-alkyl acrylate copolymers (methyl, ethyl, butyl, octyl, phenyl acrylate), styrene-alkyl methacrylate copolymers ( methyl, ethyl, butyl, phenyl methacrylate), styrene - methyl chloroacrylate copolymers and styrene - acrylonitrile - alkyl acrylate copolymers. In these copolymers, the comonomer content generally ranges up to 20% by weight. The present invention also relates to metallocene polystyrenes with a high melting point!

It would not be departing from the scope of the invention if (A) were a mixture of two or more of the preceding polymers.

The styrene polymer A preferably comprises more than 50% by weight of styrene. In the case where the styrene polymer is SAN, it preferably contains more than 75% by weight of styrene.

The polymers (B) containing polyamide blocks and polyether blocks result from the copolycondensation of polyamide blocks with reactive ends with polyether blocks with reactive ends, such as, inter alia: 1) Polyamide sequences with diamine chain ends with polyoxyalkylene sequences with dicarboxylic chain ends.

2) Polyamide sequences at the ends of dicarboxylic chains with polyoxyalkylene sequences at the ends of diamine chains obtained by cyanoethylation and hydrogenation of polyoxyalkylene alpha-omega dihydroxylated aliphatic sequences called polyetherdiols.

3) Polyamide sequences at the ends of dicarboxylic chains with polyetherdiols, the products obtained being, in this particular case, polyetheresteramides. The copolymers (B) are advantageously of this type.

The polyamide sequences with dicarboxylic chain ends originate, for example, from the condensation of alpha-omega aminocarboxylic acids, lactams or dicarboxylic acids and diamines in the presence of a chain-limiting dicarboxylic acid.

The number-average molar mass Mn of the polyamide blocks is between 300 and 15,000 and preferably between 600 and 5,000. The mass Mn of the polyether blocks is between 100 and 6,000 and preferably between 200 and 3,000. polyamide blocks and polyether blocks can also comprise randomly distributed patterns. These polymers can be prepared by the simultaneous reaction of polyether and precursors of polyamide blocks.

For example, polyetherdiol, a lactam (or an alpha-omega amino acid) and a chain-limiting diacid can be reacted in the presence of a little water. A polymer is obtained which essentially has polyether blocks, polyamide blocks of very variable length, but also the various reactants which have reacted randomly which are distributed statistically along the polymer chain. These polymers containing polyamide blocks and polyether blocks, whether they originate from the copolycondensation of polyamide and polyether blocks prepared beforehand or from a reaction in one step, exhibit, for example, shore D hardnesses which may be between 20 and 75 and advantageously between 30 and 70 and an intrinsic viscosity between 0.8 and 2.5 measured in metacresol at 250 ° C for an initial concentration of 0.8 g / 100 ml. The MFIs can be between 5 and 50 (235 ° C under a load of 1 kg). The polyetherdiol blocks are either used as such and copolycondensed with polyamide blocks with carboxylic ends, or they are aminated to be transformed into polyether diamines and condensed with polyamide blocks with carboxylic ends. They can also be mixed with polyamide precursors and a chain limiter to make polymers with polyamide blocks and polyether blocks having randomly distributed units.

Polymers containing polyamide and polyether blocks are described in patents US 4,331,786, US 4,115,475, US 4 195015, US 4839441, US 4 864 014, US 4230838 and US 4332920.

According to a first form of the invention The polyamide sequences with dicarboxylic chain ends originate, for example, from the condensation of alpha-omega aminocarboxylic acids, lactams or dicarboxylic acids and diamines in the presence of a chain-limiting dicarboxylic acid. . As an example of alpha omega aminocarboxylic acids, there may be mentioned aminoundecanoic acid, as an example of a lactam, there may be mentioned caprolactam and lauryllactam, as an example of dicarboxylic acid, there may be mentioned adipic acid. , decanedioic acid and dodecanedioic acid, by way of example of a diamine, mention may be made of hexamethylene diamine. Advantageously, the polyamide blocks are made of polyamide 12 or of polyamide 6. The melting temperature of these polyamide blocks which is also that of the copolymer (B) is generally 10 to 15 ° C. below that of PA 12 or PA 6. According to the nature of (A) it may be useful to use a copolymer (B) having a lower melting temperature so as not to degrade (A) during the incorporation of (B), this is what is the subject of the second and third forms of the invention below.

According to a second form of the invention, the polyamide sequences result from the condensation of one or more alpha omega aminocarboxylic acids and / or of one or more lactams having from 6 to 12 carbon atoms in the presence of a dicarboxylic acid having 4 to 12 carbon atoms and are of low mass, that is to say Mn from 400 to 1000. By way of example of alpha omega aminocarboxylic acid, mention may be made of aminoundecanoic acid and aminododecanoic acid. By way of example of dicarboxylic acid, mention may be made of adipic acid, sebacic acid, isophthalic acid, butanedioic acid, 1,4 cyclohexyldicarboxylic acid, terephthalic acid, sodium salt or lithium acid sulphoisophthalic, dimerized fatty acids (these dimerized fatty acids have a dimer content of at least 98% and are preferably hydrogenated) and dodecanedioic acid HOOC- (CH2) ιo-COOH.

By way of example of a lactam, mention may be made of caprolactam and lauryl lactam.

Caprolactam should be avoided unless the polyamide is purified from the monomeric caprolactam which remains dissolved therein.

Polyamide sequences obtained by condensation of lauryllactam in the presence of adipic acid or dodecanedioic acid and of mass Mn 750 have a melting temperature of 127-130 ° C.

According to a third form of the invention, the polyamide sequences result 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 an aliphatic diamine having from 6 to 12 atoms, it can be arylic and / or cyclic saturated.

Examples include hexamethylenediamine, piperazine, 1-aminoethylpiperazine, bisaminopropylpiperazine, tetramethylene diamine, octamethylene diamine, decamethylene diamine, dodecamethylene diamine, 1.5 diaminohexane, 2.2, 4-trimethyl, 6-diamino-hexane, polyols diamine, isophorone diamine (IPD), methyl pentamethylenediamine (MPDM), bis (aminocyclohexyl) methane (BACM), bis (3-methyl-4 aminocyclohexyl) methane (BMACM). In the second and third forms of the invention, the various constituents of the polyamide block and their proportion are chosen to obtain a melting temperature below 150 ° C. and advantageously between 90 and 135 ° C. Copolyamides at low melting temperature are described in US Patents 4,483,975, DE 3,730,504, US 5,459,230. The same proportions of the constituents are used for the polyamide blocks of (B). (B) can also be the copolymers described in US 5489

667.

The polyether blocks can represent 5 to 85% by weight of (B). The polyether blocks can contain other units than the ethylene oxide units such as, for example, propyiene oxide or polytetrahydrofuran (which leads to polytetramethylene glycol sequences). PEG blocks can also be used simultaneously, ie those made up of ethylene oxide units, PPG blocks, ie those consisting of propyiene oxide units and PTMG blocks, ie those consisting of tetramethylene glycol units also called polytetrahydrofuran. Advantageously, PEG blocks or blocks obtained by oxyethylation of bisphenols, such as for example bisphenol A, are used. These latter products are described in patent EP 613919. The quantity of polyether blocks in (B) is advantageously from 10 to 50%. by weight of (B) and preferably from 35 to 50%.

The copolymers of the invention can be prepared by any means allowing the polyamide blocks and the polyether blocks to be attached. In practice, essentially two methods are used, one said in 2 steps, the other in one step.

The 2-step process consists first of all in preparing the polyamide blocks with carboxylic ends by condensation of the polyamide precursors in the presence of a chain-limiting dicarboxylic acid, then in a second step in adding the polyether and a catalyst. If the polyamide precursors are only lactams or alpha omega aminocarboxylic acids, a dicarboxylic acid is added. If the precursors already comprise a dicarboxylic acid, it is used in excess relative to the stoichiometry of the diamines. The reaction is usually carried out between 180 and 300 ° C, preferably 200 to 260 ° C, the pressure in the reactor is established between 5 and 30 bars, it is maintained for approximately 2 hours. The pressure is slowly reduced by putting the reactor into the atmosphere and then the excess water is distilled, for example an hour or two.

The polyamide with carboxylic acid ends having been prepared, the polyether and a catalyst are then added. The polyether can be added one or more times, as can the catalyst. According to an advantageous form, the polyether is first added, the reaction of the OH ends of the polyether and of the COOH ends of the polyamide begins with ester bond formations and elimination of water; Water is removed as much as possible from the reaction medium by distillation and then the catalyst is introduced to complete the bonding of the polyamide blocks and of the polyether blocks. This second step is carried out with stirring preferably under a vacuum of at least 5 mm Hg (650 Pa) at a temperature such that the reagents and the copolymers obtained are in the molten state. By way of example, this temperature can be between 100 and 400 ° C. and most often 200 and 300 ° C. The reaction is followed by measuring the torsional torque exerted by the molten polymer on the agitator or by measuring the electric power consumed by the agitator. The end of the reaction is determined by the value of the torque or the power target. The catalyst is defined as being any product making it possible to facilitate the bonding of the polyamide blocks and of the polyether blocks by esterification. The catalyst is advantageously a derivative of a metal (M) chosen from the group formed by titanium, zirconium and hafnium. By way of example of a derivative, mention may be made of tetraalkoxides which correspond to the general formula M (OR) 4, in which M represents titanium, zirconium or hafnium and the Rs, identical or different, denote alkyl radicals, linear or branched, having from 1 to 24 carbon atoms. C- alkyl radicals | to C24 from which are chosen the radicals R of the tetraalkoxides used as catalysts in the process according to the invention are for example such as methyl, ethyl, propyl, isopropyl, butyl, ethylhexyl, decyl, dodecyl, hexadodecyl. The preferred catalysts are the tetraalkoxides for which the radicals R, which are identical or different, are C 1 to C 6 alkyl radicals. Examples of such catalysts are in particular Z _r (OC2H5) 4, Z _r (O-isoC3H7) 4, _r ( OC4Hg) 4,

Z _r (OC ₅ H ₁₁ ) 4 _I Z _r (OC ₆ H ₁ 3) 4, H _f (OC ₂ H ₅ ) 4, H _f (OC ₄ H9) 4, H _f (O-isoC ₃ H ₇ ) ₄ .

The catalyst used in this process according to the invention can consist solely of one or more of the tetraalkoxides of formula M (OR) 4 defined above. It can also be formed by the association of one or more of these tetraalkoxides with one or more alkaline or alkaline-earth alcoholates of formula (Rj O) pY in which Rj denotes a hydrocarbon residue, advantageously an C1 to C24 alkyl residue , and preferably in Cj to Cβ, Y represents an alkali or alkaline earth metal and p is the valence of Y. The amounts of alkali or alkaline earth alcoholate and of zirconium or hafnium tetraalkoxides which are combined for constitute the mixed catalyst can vary within wide limits. However, it is preferred to use amounts of alcoholate and tetraalkoxides such that the molar proportion of alcoholate is substantially equal to the molar proportion of tetraalkoxide.

The proportion by weight of catalyst, that is to say of the tetraalkoxide (s) when the catalyst does not contain alkali or alkaline earth alcoholate or of all of the tetraalkoxide (s) and of alkaline or alkaline alcoholate (s) earthy when the catalyst is formed by the association of these two types of compounds, advantageously varies from 0.01 to 5% of the weight of the mixture of the polyamide dicarboxylic with the polyoxyalkylene glycol, and is preferably between 0.05 and 2% of this weight. By way of example of other derivatives, mention may also be made of the salts of the metal (M) in particular the salts of (M) and of an organic acid and the complex salts between the oxide of (M) and / or l hydroxide of (M) and an organic acid. Advantageously, the organic acid can be formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauryac acid, acid myristic, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, cyclohexane carboxylic acid, phenylacetic acid, benzoic acid, salicylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, phthalic acid and crotonic acid. Acetic and propionic acids are particularly preferred. Advantageously M is, zirconium. These salts can be called zirconyl salts. The Applicant, without being bound by this explanation, believes that these zirconium and organic acid salts or the complex salts mentioned above release ZrO ⁺⁺ during the process. The product sold under the name of zirconyl acetate is used. The quantity to be used is the same as for the derivatives M (OR) 4.

This process and these catalysts are described in US patents 4,332,920, US 4,230,838, US 4,331,786, US 4,252,920, JP 07145368A, JP 06287547A, and EP 613919.

With regard to the one-step process, all the reagents used in the two-step process are mixed. that is to say the polyamide precursors, the chain-limiting dicarboxylic acid, the polyether and the catalyst. These are the same reagents and the same catalyst as in the two-step process described above. If the polyamide precursors are only lactams, it is advantageous to add a little water.

The copolymer has essentially the same polyether blocks, the same polyamide blocks, but also a small part of the various reactants which have reacted randomly which are distributed statistically along the polymer chain.

The reactor is closed and heated with stirring as in the first step of the two-step process described above. The pressure is established between 5 and 30 bars. When it no longer evolves, the reactor is placed under reduced pressure while maintaining vigorous stirring of the molten reactants. The reaction is followed as above for the two-step process. The catalyst used in the one-step process is preferably a salt of the metal (M) and an organic acid or a complex salt between the oxide of (M) and / or the hydroxide of (M) and an acid organic. The ingredient (B) can also be a polyetheresteramide (B) having polyamide blocks comprising sulfonates of dicarboxylic acids either as chain limiters of the polyamide block or associated with a diamine as one of the constituent monomers of the polyamide block and having polyether blocks essentially consisting of alkylene oxide units, as described in international application PCT / FR00 / 02889.

As regards compatibilizer C, it can be any block copolymer comprising at least one polymerized block comprising styrene and at least one polymerized block comprising methyl methacrylate. The polymerized block comprising styrene is generally present in C at a rate of 20 to 80% by weight.

The polymerized block comprising methyl methacrylate is generally present in C in an amount of 20 to 80% by weight.

The polymerized block comprising styrene generally has a glass transition temperature greater than 100 ° C. and preferably comprises at least 50% by weight of styrene. The polymerized block comprising styrene can also comprise an unsaturated epoxide (obtained by copolymerization), the latter preferably being glycidyl methacrylate. The unsaturated epoxide can be present in an amount of 0.01% to 5% by weight in the polymerized block comprising styrene.

The polymerized block comprising methyl methacrylate generally has a glass transition temperature above 100 ° C. and preferably comprises more than 50% by weight of methyl methacrylate. The polymerized block comprising methyl methacrylate can also comprise an unsaturated epoxide (obtained by copolymerization), the latter preferably being glycidyl methacrylate. The unsaturated epoxide can be present in an amount of 0.01% to 5% by weight in the polymerized block comprising methyl methacrylate.

The block copolymer comprising at least one polymerized block comprising styrene and at least one polymerized block comprising methyl methacrylate can also be grafted with an unsaturated epoxide, preferably glycidyl methacrylate.

By way of example of unsaturated epoxides, there may be mentioned: aliphatic glycidyl esters and ethers such as allyl glycidyl ether, vinyl glycidyl ether, glycidyl maleate and itaconate,

(meth) glycidyl acrylate, and - alicyclic glycidyl esters and ethers such as 2-cyclohexene-1-glycidyl ether, cyclohexene-4,5-diglycidyl carboxylate, cyclohexene-4-glycidyl carboxylate, 5-norbomene- 2-methyl-2-glycidyl carboxylate and endo cis-bicyclo (2,2,1) -5-heptene-2,3-diglycidyl dicarboxylate.

In the block comprising styrene, part of the styrene can be replaced by unsaturated monomers copolymerizable with styrene, by way of example, Palpha-methylstyrene and the esters may be mentioned

(Meth) acrylic. In this case, the block comprising styrene is a styrene copolymer which may be cited as an example, styrene-alpha-methylstyrene copolymers, styrene-chlorostyrene copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene copolymers -vinyl chloride, styrene-vinyl acetate copolymers, styrene-alkyl acrylate copolymers (methyl, ethyl, butyl, octyl, phenyl acrylate), styrene-alkyl methacrylate copolymers ( (methyl, ethyl, butyl, phenyl methacrylate), styrene - methyl chloroacrylate copolymers and styrene - acrylpnitrile - alkyl acrylate copolymers.

In particular, C can be: a diblock copolymer comprising a block of a polymer of styrene and a block of a polymer of methyl methacrylate; a diblock copolymer comprising a block of a styrene polymer and a block of poly (methyl methacrylate-glycidyl co-methacrylate); a diblock polymer copolymer of styrene-polymer of methyl methacrylate, said copolymer being grafted with glycidyl methacrylate; a diblock copolymer comprising a homopolystyrene block and a methyl homopolymethacrylate block; a diblock copolymer comprising a homopolystyrene block and a poly (methyl methacrylate-co-glycidyl methacrylate) block; - a homopolystyrene-methyl homopolymethacrylate diblock copolymer, said copolymer being grafted with glycidyl methacrylate; a diblock copolymer comprising a block of polystyrene-glycidyl co-methacrylate and a block of polymethyl methacrylate; a diblock copolymer comprising a block of polystyrene-glycidyl co methacrylate and a block of poly (methyl methacrylate-glycidyl co-methacrylate); Furthermore, C can also be a triblock copolymer SBM, S representing the polymerized block comprising styrene, M representing the polymerized block comprising methyl methacrylate, B representing an elastomeric block having a glass transition temperature (Tg) of less than 5 °. C, preferably less than 0 ° C and more preferably less than -40 ° C.

The monomer used to synthesize the elastomeric block B can be a diene chosen from butadiene, isoprene, 2,3-dimethylM, 3-butadiene, 1, 3-pentadiene, 2-phenyl-1,3-butadiene . B is advantageously chosen from poly (dienes), in particular poly (butadiene), poly (isoprene) and their random copolymers, or also from poly (dienes) partially or completely hydrogenated. Among the polybutadienes, those with the lowest Tg are advantageously used, for example 1,4-polybutadiene with Tg (around -90 ° C.) lower than that of 1,2-polybutadiene. (around 0 ° C). B blocks can also be hydrogenated. This hydrogenation is carried out according to the usual techniques.

The monomer used to synthesize the elastomeric block B can also be an alkyl (meth) acrylate, the following Tg are obtained in parentheses according to the name of the acrylate: ethyl pacrylate (-24 ° C), butyl pacrylate , (-54 ° C), 2-ethylhexyl acrylate (-85 ° C), hydroxyethyl acrylate (-15 ° C) and 2-ethylhexyl methacrylate (-10 ° C). Advantageously, butyl acrylate is used.

Preferably, the blocks B consist mainly of polybutadiene-1, 4.

Thus, C can be: - a triblock copolymer S-B-M in which S is a block of a polymer of styrene, B is a block of polybutadiene, and M is a block of a polymer of methyl methacrylate; a triblock copolymer S-B-M in which S is a block of homopolystyrene, B is a block of polybutadiene, and M is a block of methyl homopolymethacrylate;

It would not go beyond the scope of the invention to use one or more compatibilizers C. The compatibilizer C can in particular be prepared by controlled radical polymerization techniques in the presence of a stable free radical (generally a nitroxide) on the principle of the teaching of EP 927727. SBM can be obtained by anionic route.

Anti-statism increases with the proportion of (B) and for equal amounts of (B) with the proportion of ethylene oxide units contained in (B).

Depending on the application, it may be preferable to include a proportion of (B) sufficient for obtaining, at the level of the final composition, a surface resistivity measured according to standard IEC93 Less than 5.10 ¹³ Ω / D. Depending on the application, it may be preferable to include a proportion of (B) in sufficient proportion so that the final composition has a volume resistivity measured according to the IEC93 standard less than 5.10 ¹⁶ Ω.cm. The amount of (B) + (C) is advantageously from 5 to 30 parts for

95 to 70 parts of (A) and preferably 10 to 20 for 90 to 80 parts of (A). The ratio (B) / (C) is advantageously between 4 and 10. The amount of C in the composition can range from 0.5 to 5 parts by weight per 100 parts by weight of composition. We would not go beyond the scope of the invention by adding mineral fillers (talc, CasCO, kaolin, etc.), reinforcements (fiberglass, mineral fiber, carbon fiber, etc.), stabilizers (thermal, UV), flame retardants and dyes.

The compositions of the invention are prepared by the usual techniques of thermoplastics such as for example by extrusion or using twin-screw mixers.

The present invention also relates to objects manufactured with the preceding compositions; these are, for example, films, tubes, plates, packaging, computer, fax or telephone cases.

In the following examples, the following abbreviations are used: GMA: glycidyl methacrylate; MAM: methyl methacrylate; MS: polystyrene-block-polymethyl methacrylate; - SM / GMA: polystyrene-polymethyl methacrylate block grafted / copolymerized with glycidyl methacrylate; PEG: polyethylene glycol; PMMA: polymethyl methacrylate; Mw: mass average molecular weight; Mn: average molecular mass in number; Mw / Mn: polydispersity - Rv: volume resistivity (Ω.cm)

Rs: surface resistivity (Ω / D)

HO-TEMPO: 4-hydroxy ~ 2,2,6,6-tetramethyl-1 ~ ρiperidinyloxy usually sold under the name 4-hydroxy TEMPO; SEC: size exclusion chromatography; - LAC: liquid adsorption chromatography;

GPC: gel permeation chromatography; NMR: nuclear magnetic resonance; TEM: transmission electron microscopy; In the following examples, the following ingredients are used: - PS 4241: styrene - butadiene copolymer. This copolymer has a melt index at 200 ° C under 5 kg of between 3 and 5 g / 10 min (standard ISO 1133: 91) It is also characterized by a Vicat temperature of 97 ° C (standard ISO 306A50). This copolymer has a styrene content of approximately 95% by weight. This copolymer is marketed by the company ATOFINA under the brand Lacqrene.

MH1657: copolyether-block amide having polyamide 6 blocks of average molar mass in number 1500 and PEG blocks of average molar mass in number 1500; the melting point is 204 ° C. This copolymer is marketed by the company ATOFINA under the brand Pebax MH1657.

MS: this is a polystyrene-block- (polymethyl methacrylate) block copolymer prepared by controlled radical polymerization with an M _w = 106,000 and a polydispersity of 2.1. The rate of styrene is 61% by weight. - SM / GMA: this is a polystyrene-block copolymer

(methyl methacrylate-glycidyl co-methacrylate) prepared by controlled radical polymerization with an M _w = 108,700 and a polydispersity of 2.0. The rate of styrene is 65% by weight and it contains 0.4% by weight of GMA. In the following examples, the following characterization techniques were used:

Mechanical properties : The compositions obtained are injected on a press at temperatures of 220 to 240 ° C in the form of dumbbells, bars or plates. The dumbbells make it possible to carry out the tensile tests of standard ISO R527 and the bars are used for the Charpy impact notched according to standard ISO 179: 93 1eA.

Antistatic properties: Plates with the following dimensions 100x100x2 mm ³ are injection molded and allow the resistivity measurement tests to be carried out according to the IEC-93 standard.

In the tables, the volume resistivity measured in ohm.cm is given, the surface resistivity measured in ohm / D; the properties obtained in tension are also given.

All tests are carried out at 23 ° C. The plates are conditioned at 50% humidity for 15 days before being tested for the measurement of surface resistivity. EXAMPLES 1 TO 6 a) preparation of compatibilizers C (Description of the procedure for the synthesis of SM and SM / GMA) Two steel jackets are used in cascade.

The reactors are connected by a thermally insulated piping and wound with heating cord preventing any cooling during the casting.

Styrene, solvent, initiator and OH-TEMPO (from the family of nitroxides) are introduced into the reactor under atmospheric pressure, then heated to 140 ° C. A kinetic study is carried out on the reaction mixture and this is why samples are taken from the

- time when the temperature of the reaction mixture reaches approximately 130 ° C.

All these samples are flashed (at 170 ° C. in a vacuum chamber) in order to determine the rate of conversion of styrene to polystyrene. After approximately 60-70% conversion to polystyrene, methyl methacrylate previously heated in the top reactor is added in a single addition.

100 ° C.

The reaction mixture is brought to approximately 140 ° C. for approximately 3 hours and then subjected to devolatilization so as to remove the volatile species. The copolymer is recovered in the form of granules.

The following table presents the quantities of reagents used in the first stage of the synthesis for these two tests.

Experimental conditions:

Oil bath temperature: 160 ° C, Condenser temperature: - 20 ° C. The origin of the times for the conversion of styrene is chosen when the temperature of the polymerization medium reaches 130 ° C.

The quantity of MAM (or MAM / GMA mixture is preheated to boiling before being added to the reaction mixture. The temperature of the oil bath is left constant at 160 ° C. The condenser valve is in the closed position. stabilizes by increasing the pressure in the reactor (P = 1.5 bar) at 120 ° C. The product is then recovered in the form of granules. The product is analyzed in LAC, GPC and NMR as well as in TEM. after having carried out a film by slow evaporation in chloroform. In addition to these SEC analyzes, quantitative LAC analyzes were carried out. With this technique, it was then possible to quantify the homopolystyrene and homoPMMA levels present in the reaction mixture. , then to determine the mass composition of polystyrene and PMMA of the copolymers. Finally, an NMR analysis of the reaction mixture also allowed us to determine the triad rates MMM, SMS and MMS representative of cop block or statistical olymer (MMM = three units of neighboring MAM, SMS = unit of styrene followed by MAM which is followed by S, and MMS ≈ unit of MAM followed by MAM which is followed by styrene). The determination of this rate makes it possible to characterize the structuring of the block copolymer. A percentage of 100% MMM triad means perfect structuring.

All the results are provided in the following table:

All of these results show that the products obtained are rich in block copolymers since both the homopolystyrene level is close to 30%, that there is no PMMA homopolymer and that finally the MMM triad rate is over 70%. In addition, TEM analyzes of these products show lamellar structures. Whatever the test, the structure obtained is always of the lamellar type throughout the space. It can be noted that the polystyrene lamellae are swollen with homopolystyrene since the thicknesses of these lamellae are greater than those of PMMA although the composition of the copolymer is of the order of 50/50. The polystyrene-block-PMMA block copolymer has a content

_ in styrene of 45% by weight and an MMA content of 55% by weight. b) preparation of compositions by mixing in an extruder. A Werner and Pfleiderer twin screw extruder with a diameter of 30mm is used with a total throughput of 20 kg / h. This flow represents the sum of the flows of the ingredients used. The target temperatures for the sleeves are 230 to 250 ° C. The rods from the machine are cooled in a water tank and are transformed into granules. These granules are injected in the form of plates, bars or dumbbells at similar temperatures (230 to 250 ° C). The results reported in the table above make it possible to demonstrate the compatible action of the block copolymer SM and SM / GMA. The block copolymers were used as obtained without separation from the homopolystyrene which was mixed with it. This homopolystyrene can be considered to be a styrene resin (A). In the results table below, the amounts of SM and SM / GMA indicated correspond to amounts of pure copolymer. The amounts of homopolystyrene provided during the addition of block copolymer are reported in the second row of the table.

Indeed, the elongation at break and the stress at break are improved while the impact properties of the matrix are preserved and the composition is made antistatic.

The influence of block copolymers is also visible in terms of particle size. For test 1, the particle size is of the order of

1 μm whereas for examples 5 and 6, this is reduced by half (0.5 μm). The reduction in particle size is generally accompanied by

15 of a better compatibilizing action of the block copolymer.

Claims

1. composition comprising per 100 parts by weight: - 99 to 60 parts by weight of a styrene polymer (A),

- 1 to 40 parts by weight of (B) + (C), (B) being a copolymer with polyamide blocks and polyether blocks essentially comprising ethylene oxide units - (C2H4— O) -, (C) being a compatibilizer chosen from block copolymers comprising at least one polymerized block comprising styrene and at least one polymerized block comprising methyl methacrylate, the mass ratio (B) / (C) being between 2 and 10.

2 Composition according to claim 1 in which (B) is in sufficient proportion so that the final composition has a surface resistivity measured according to standard IEC93 Less than 5.10 ¹³ Ω / D.

3 Composition according to one of the preceding claims in which (B) is in sufficient proportion so that the final composition has a volume resistivity measured according to standard IEC93 less than 5.10 ¹⁶ Ω.cm. 4 Composition according to one of the preceding claims in which (A) comprises more than 50% of styrene.

5 Composition according to one of the preceding claims, characterized in that the amount of (C) ranges from 0.5 to 5 parts by weight in

100 parts by weight of composition. 6 Composition according to one of the preceding claims, characterized in that the polymerized block comprising styrene is present in C at a rate of 20 to 80% by weight.

7 Composition according to one of the preceding claims, characterized in that the polymerized block comprising methyl methacrylate is present in C at a rate of 20 to 80% by weight.

8 Composition according to one of the preceding claims, characterized in that the polymerized block comprising styrene comprises at least 50% by weight of styrene.

9 The polymerized block comprising styrene includes glycidyl methacrylate.

10 Composition according to one of the preceding claims, characterized in that the polymerized block comprising methyl methacrylate comprises more than 50% by weight of methyl methacrylate. 11 Composition according to one of the preceding claims, characterized in that the polymerized block comprising methyl methacrylate comprises glycidyl methacrylate.

12 Composition according to one of the preceding claims, characterized in that the block copolymer comprising at least one polymerized block comprising styrene and at least one polymerized block comprising methyl methacrylate is grafted with glycidyl methacrylate.

13 Composition according to one of the preceding claims, characterized in that (A) is a styrene-butadiene copolymer.

14 Composition according to one of the preceding claims in which the amount of (B) + (C) is from 5 to 30 parts per 95 to 70 parts of (A).

15 Composition according to the preceding claim in which the amount of (B) + (C) is from 10 to 20 for 90 to 80 parts of (A).

16 Composition according to one of the preceding claims, characterized in that (C) is an SBM triblock copolymer, S representing the polymerized block comprising styrene, M representing the polymerized block comprising methyl methacrylate, B representing an elastomeric block having a temperature glass transition (Tg) less than 5 ° C.

17 Objects made in a composition according to one of the preceding claims.

18 Use of the subject of the preceding claim to come into contact with electronic components.