EP1866353A2 - Adaptable block copolymer with acid functions and adhesive composition and thermoplastic containing same - Google Patents

Abstract

The invention concerns a linear ethylene copolymer, comprising: at least a first sequence A having a glass transition temperature higher than 20 °C; at least a second sequence B having a glass transition temperature less than 15 °C; at least a third sequence C having a glass transition temperature higher than 20 °C; said first sequence A and third sequence C being identical or different, and at least one of them comprising at least one monomer unit including at least a -CO2H and/or carboxylate-COO function. Said copolymer is used in adhesive compositions and thermoplastic compositions.

Description

COPOLYMER SEQTJENCE WITH MODULABLE ACID FUNCTIONS AND ADHESIVE AND THERMOPLASTIC COMPOSITION CONTAINING SAME

DESCRIPTION

TECHNICAL FIELD

The present invention relates to modulatable block copolymers which can be used, in particular in adhesive compositions, such as hot-melt adhesive pressure-sensitive compositions (also known as HMPSA), and in thermoplastic compositions. Generally, the adhesive compositions, such as hot-melt pressure-sensitive compositions, used in particular in tape and adhesive label applications must have a compromise of properties between their implementation (thermal stability, viscosity level, etc.) and their properties. physical (adhesion, cohesion and temperature resistance ...). It is generally the same for thermoplastic compositions.

It is known, in the field of polymers, that the addition of monomers such as methacrylic acid, acrylic acid, makes it possible to benefit from an ionomeric effect, by neutralization of the acid functions by a base, and thus to control the physical properties of the polymer such as the polymer modulus level and the temperature resistance.

Until now, polymers of this kind have characteristics that make them difficult to incorporate into adhesive compositions, especially adhesive compositions. thermofusibles sensitive to pressure, because of their incompatibility with the ingredients commonly used in these compositions, such as tackifying resins, oils. There is therefore a real need for new polymers whose physical properties

(Such as mechanical, thermomechanical, rheological properties) can be modulated by simple neutralization of acidic functions, and which can easily be incorporated into adhesive or thermoplastic compositions, without resorting to polymer grades to access the desired physical properties for of a given use.

STATEMENT OF THE INVENTION

Thus, the invention relates, according to a first object, to a block copolymer, ethylenic, linear comprising:

at least one first block A having a glass transition temperature greater than 20 ^° C., preferably greater than 60 ^° C.

at least one second block B having a glass transition temperature of less than 15 ^° C., preferably less than -30 ^° C. at least one third C sequence having a glass transition temperature greater than 20 ^° C., preferably greater than 60 ^° C .; said first sequence A and third block C being identical or different and at least one of them comprising at least one monomeric unit comprising at least one -CO ₂ H and / or carboxylate -C00 ^"function .

Such copolymers are particularly advantageous, in the sense that it is easily conceivable with these to modulate their physical properties, such as thermomechanical properties and rheological properties, by controlling the degree of neutralization of the functions -CO ₂ H. Thus, from a copolymer as defined above, it is possible by neutralizing all or part of the acid functions -CO ₂ H to increase the elastic shear modulus and its temperature resistance by giving it more cohesion. In fact, with the ionization of the copolymers, their glass transition temperature increases, and the ionic interactions make it possible to create electrostatic bridges between the polymer chains, which influences their mechanical strength. From the copolymers of the invention, it is also possible by neutralizing all or part of the acid functional groups -CO ₂ H to control the melt viscosity and thus to selectively increase the low shear rate viscosity (for a better creep resistance, for example) while having a much more moderate increase in viscosity for high shear gradients. As a result, the copolymers of the invention are of particular interest for formulations comprising a solvent, since control of the viscosity in these formulations can be crucial (especially for example, to maintain solid particles in stable suspension).

It is thus possible, with the aid of a single copolymer grade of the invention, to see its properties adapt to a given field of application by resorting to a judicious neutralization.

In addition, because of their intrinsic properties (especially the glass transition temperatures of the blocks), the copolymers can be easily incorporated with other ingredients commonly encountered in adhesive and thermoplastic compositions.

The copolymers of the invention are linear block ethylenic copolymers. By ethylenic copolymer is meant a copolymer obtained by polymerization of monomers comprising ethylenic unsaturation.

By block copolymer is meant a copolymer comprising several distinct successive sequences (in this case, in our case, at least three), that is to say of different chemical natures.

The copolymers of the invention are polymers with a linear structure. In contrast, a nonlinearly structured polymer is, for example, a branched, star-shaped, grafted, or other polymer. In particular, all the monomers used to prepare a linear polymer are monofunctional, that is to say have only one polymerizable function.

The polymerization initiators may, for their part, be monofunctional or difunctional. According to the invention, the copolymers comprise respectively a first sequence A and a third sequence C, which are identical or different, both having respectively a glass transition temperature greater than 20 ^° C., at least one of its sequences comprising at least one monomer unit comprising at least one function -CO ₂ H and / or -COO ^". in general, these monomer units are included in the sequence given in a content ranging from 0.5 to 99 mol%, preferably from 3 to 30% more preferably 3 to 20 mol% This means that these sequences are generally derived from several different types of monomers and thus consist of a copolymer, this copolymer constituting the sequence that can be in turn statistical or alternating or gradient the distribution of the monomers within each sequence can therefore be random or controlled depending on the nature and / or the reactivity of the monomers and / or the process. According to the invention, a monomer unit is understood to mean a unit directly derived from a monomer after polymerization thereof.

In said sequence A and / or C, the monomers giving rise, after polymerization, to monomeric units comprising at least one --CO ₂ H function that may be used may be chosen from the monomers corresponding to the following formula (I) :

(I)

in which :

R 1 is a hydrogen atom or a linear or branched hydrocarbon group of type C _p H _{2p +} 1, with p being an integer ranging from 1 to 12;

Z is a divalent group selected from -COO-, -CONH-, -CONCH ₃ -, -OCO- or -O-; preferably -COO- and -CONH-; x is an integer equal to 0 or 1, preferably 1;

R ₂ is a saturated or unsaturated, optionally aromatic, linear, branched or cyclic divalent carbon group comprising from 1 to 30 carbon atoms and may comprise from 1 to 30 heteroatoms chosen from O, N, S, and P;

m is an integer equal to 0 or 1. Advantageously, in formula (I), R 1 is a hydrogen atom or a methyl group, x is equal to 0 and m is equal to 0.

In the group R ₂ , the one or more heteroatoms, when present, may be inserted in the chain of said group R ₂ , or said group R ₂ may be substituted by one or more groups including them, such as a hydroxyl group or amino (NH ₂ , NHR 'or NR' R "with R 'and R", identical or different, representing a linear or branched C 1 -C ₂₂ alkyl group, especially a methyl or ethyl group). In particular R ₂ can be:

an alkylene group such as a methylene, ethylene, propylene, n-butylene, isobutylene, tert-butylene, n-hexylene, n-octylene, n-dodecylene, n-octadecylene, n-tetradecylene, n-docosanylene group;

a phenylene-C ₆ H ₄ - (ortho, meta or para) group optionally substituted with a C 1 -C 12 alkyl group optionally comprising from 1 to 8 heteroatoms chosen from O, N, S, and P; or benzylene -C ₅ H ₄ -CH ₂ - optionally substituted by alkyl, Ci-Ci ₂ optionally comprising 1 to 8 heteroatoms selected from 0, N, S, and P;

a group of formula -CH ₂ -CHOH-, -CH ₂ -CH ₂ -CHOH-, -CH ₂ -CH ₂ -CH (NH ₂ ) -, -CH ₂ -CH (NH ₂ ) -,

-CH ₂ -CH ₂ -CH (NHR ') -, -CH ₂ -CH (NHR') -, -CH ₂ -CH ₂ -CH (NR ¹ R ") -, -CH ₂ -CH (NR ¹ R ") -, -CH ₂ -CH = CH- where R 'and R", identical or different, representing a linear or branched Ci-Ci _8, especially methyl or ethyl Among the monomers capable of giving rise to. monomer units comprising -CO ₂ H functions that are more particularly preferred, mention may be made in particular of acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, and acid. diacrylic acid, dimethylfumaric acid, citraconic acid, vinylbenzoic acid, acrylamidoglycolic acid of formula CH ₂ = CH-CONHCH (OH) COOH, diallyl maleate of formula C ₃ H ₅ -CO ₂ -CH = CH-CO ₂ -C ₃ H ₅ , tert-butyl (meth) acrylate, carboxylic anhydrides bearing a vinyl bond, and their salts, and their mixtures. It is understood that, for the esters mentioned above, these will, after polymerization, be hydrolyzed to give the units carrying -CO ₂ H functions. In said sequence A and / or C, the monomers giving rise, after polymerization, to monomer units comprising at least one carboxylate function which may be used may also be chosen from the monomers corresponding to the following formula (II):

(H) wherein:

Ri, Z, x, R ₂ and m have the same meanings as in formula (I) above;

X ¹⁺ is a divalent group of formula -N ⁺ R ' ₅ R' ₇ with R '6 and RZ ₇ representing, independently of one another,

(i) a hydrogen atom, (ii) a linear, branched or cyclic, optionally aromatic, alkyl group comprising from 1 to 30 carbon atoms, which may comprise from 1 to 8 heteroatoms selected from O, N, S and P; for example a methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl or isobutyl group;

(iii) an alkylene oxide group of formula - (R ' ₈ O) _y R' ₉ with R ' ₈ representing a linear or branched C ₂ -C ₄ alkyl group, R' ₉ representing an atom hydrogen or a linear or branched C 1 -C ₃₀ alkyl group and y is an integer from 1 to 250;

(iv) R ' ₆ and R' 7 may form with the nitrogen atom a saturated or unsaturated, optionally aromatic ring (NR ' ₅ R' ₇ or R ' ₅ NR' ₇ ) comprising in total 5, 6, 7 or 8 atoms, and especially 4, 5, 6 or 7 carbon atoms and / or 2 to 4 heteroatoms selected from 0, S and N; said cycle being fusible with one or more other rings, saturated or unsaturated, optionally aromatic, each comprising 5, 6, 7 or 8 atoms, and in particular 4, 5, 6 or 7 carbon atoms and / or 2 to 4 selected heteroatoms among 0, S and N;

R ₃ is a saturated or unsaturated, optionally aromatic, linear, branched or cyclic divalent carbon group comprising from 1 to 30 carbon atoms, which may comprise from 1 to 18 heteroatoms chosen from O, N, S and P;

n is an integer equal to 0 or 1. In the group R ₃ , the heteroatom (s), when they are present, may be inserted in the chain of said R ₃ group, or said R ₃ group may be substituted by one or several groups including them such as hydroxy or amino; in particular R ₃ can be:

an alkylene group such as a methylene, ethylene, propylene, n-butylene, isobutylene, tert-butylene, n-hexylene, n-octylene, n-dodecylene, n-octadecylene, n-tetradecylene, n-docosanylene group; a phenylene-C ₆ H ₄ - (ortho, meta or para) group optionally substituted with a C 1 -C 12 alkyl group optionally comprising from 1 to 5 heteroatoms chosen from O, N, S, F, Si and P; or benzylene group -C ₆ H ₄ -CH ₂ - optionally substituted by alkyl, Ci-Ci ₂ optionally comprising 1 to 5 heteroatoms selected from 0, N, S and P.

In addition to the monomeric units comprising at least one -CO ₂ H function, the A and / or C sequences may comprise one or more monomer units derived from additional monomers chosen from hydrophilic nonionic monomers, hydrophobic monomers and their mixtures.

These additional monomers may be identical or different from one sequence to another.

This or these additional monomers are ethylenic monomers copolymerizable with the ionic hydrophilic monomer or monomers, whatever their coefficient of reactivity. Preferably, the nonionic hydrophilic monomers may be present in a proportion of from 0 to 98% by weight, relative to the weight of the block, in particular from 2 to 95% by weight, and still more preferably from 3 to 92% by weight, in at least one sequence, or even in each sequence.

Preferably, the hydrophobic monomers may be present in a proportion of from 0 to 98% by weight, relative to the weight of the block, in particular from 2 to 95% by weight, and still more preferably from 3 to 92% by weight, in at least a sequence, even in each sequence. Among the hydrophilic non-ionic or hydrophobic monomers that can be copolymerized with the precursor monomers of monomer units carrying COH 2 functions mentioned above to form the polymers according to the invention, mention may be made, alone or as a mixture, of:

(i) ethylenic hydrocarbons comprising from 2 to 10 carbons, such as ethylene, isoprene or butadiene; - (ϋ) the (meth) acrylates of formula:

R ₂

H ₂ C = C COOR ₃

in which R ₂ is a hydrogen atom or a methyl group (CH ₃ ) and R ₃ represents:

a linear or branched alkyl group comprising from 1 to 30 carbon atoms, in which one or more heteroatoms chosen from O, N, S and P are optionally intercalated; said alkyl group may further be optionally substituted with one or more substituents selected from OH, halogen atoms (Cl, Br, I and F), and -Si (R ' ₄ R' ₅ R 'e and -Si (R ' ₄ R' 5) O, in which R ' ₄ , R' 5 and R '5, which may be identical or different, represent a hydrogen atom, a Ci-C ₆ alkyl group or a group phenyl; in particular R ₃ may be methyl, ethyl, propyl, n-butyl, isobutyl, tert-butyl, hexyl, ethylhexyl, especially ethyl-2-hexyl, octyl, lauryl, isooctyl, isodecyl, dodecyl, cyclohexyl, t-butylcyclohexyl or stearyl; ethyl-2-perfluorohexyl, ethyl-2-perfluorooctyl; or a hydroxyalkyl group in Ci-C ₄ such as 2-hydroxyethyl, 2-hydroxybutyl and 2-hydroxypropyl; or alkoxy (Ci-C ₄₎ alkyl (Ci-C ₄₎ such as methoxyethyl, ethoxyethyl and methoxypropyl,

- cycloalkyl C ₃ to C _2, such as an isobornyl group,

a C ₃ to C ₂₀ aryl group such as phenyl; a C ₄ to C ₃₀ aralkyl group (C 1 to C ₈ alkyl group) such as a 2-phenylethyl, t-butylbenzyl group; or benzyl,

a heterocyclic group comprising from 4 to 12 ring members containing one or more heteroatoms chosen from O, N and S, the ring being aromatic or not,

a heterocycloalkyl (alkyl of 1 to 4 carbon atoms) group, such as a furfurylmethyl or tetrahydrofurfurylmethyl group, said cycloalkyl, aryl, aralkyl, heterocyclic or heterocycloalkyl groups possibly being substituted by one or more substituents chosen from hydroxyl groups, halogen atoms, and alkyl groups Ci-C ₄ linear or branched, in which is (are) optionally intercalated (s) one or more heteroatoms selected from 0, N, s and P, said alkyl groups, in addition, optionally substituted with one or more substituents selected from -OH, halogen atoms (Cl, Br, I and F), and -Si groups (R ' ₄ R' ₅ R'e) and -Si (R ' ₄ R' ₅ ) O, in which R ' ₄ , RZ ₅ and R' ₅ , which are identical or different, represent a hydrogen atom, a C ₁ -C ₅ alkyl group, or a phenyl group,

a group - (OC ₂ H ₄ ) _m -OR '', with m = 5 to 300 and R "= H or C 1 to C ₃₀ alkyl, for example

- (OC ₂ H ₄ ) m-OH, - (OC ₂ H ₄ ) _m -O-methyl or - (OC ₂ H ₄ ) _m -O-behenyl; a group - (OC ₃ H ₅ ) _m -OR '', with m = 5 to 300 and R "= H or C 1 to C ₃₀ alkyl, for example

- (OC ₃ H ₅ ) _m -OH; or a statistical mixture or block of groups (OC ₂ H ₄ ) _m and (OC ₃ H ₅ ) _m .

(iii) (meth) acrylamides of formula:

wherein R ₈ is H or methyl; and R ₇ and R ₅ , which may be identical or different, represent: a hydrogen atom; or

a linear or branched alkyl group comprising from 1 to 30 carbon atoms, in which one or more heteroatoms chosen from O, N, S and P are optionally intercalated; said alkyl group may further be optionally substituted by one or more substituents selected from -OH, halogen atoms (Cl, Br, I and F), and -Si groups;

(R ' ₄ R' ₅ R ' ₅ ) and -Si (R' ₄ R ' ₅ ) O, wherein R' ₄ , R ' ₅ and

R _'5 represent a hydrogen atom, an alkyl group with C ₅ or phenyl; in particular, R ₅ and R ₇ may be methyl, ethyl, propyl, n-butyl, isobutyl, tert-butyl, hexyl, ethylhexyl, octyl, lauryl, isooctyl, isodecyl, dodecyl, cyclohexyl, t-butylcyclohexyl or stearyl; ethyl-2-perfluorohexyl, ethyl-2-perfluorooctyl; or a C1-4 hydroxyalkyl group such as 2-hydroxyethyl, 2-hydroxybutyl and

2-hydroxypropyl; or an alkoxy (C1-4) alkyl group

(C1-4) such as methoxyethyl, ethoxyethyl and methoxypropyl,

- cycloalkyl C ₃ to C _2, such as an isobornyl group,

a C ₃ to C ₂ aryl group such as phenyl,

a C ₄ to C ₃₀ aralkyl group (C 1 to C ₈ alkyl group) such as a 2-phenylethyl, t-butylbenzyl or benzyl group,

a heterocyclic group of 4 to 12 members containing one or more heteroatoms chosen from O, N and S, the ring being aromatic or not,

a heterocycloalkyl (C 1 -C 4) alkyl group, such as a furfurylmethyl or tetrahydrofurfurylmethyl group, said cycloalkyl, aryl, aralkyl, heterocyclic or heterocycloalkyl groups possibly being substituted by one or more substituents chosen from hydroxyl groups, halogen, and linear or branched C ₁ -C ₄ alkyl groups in which one or more heteroatoms selected from O, N, S and P are optionally intercalated, said alkyl groups being furthermore optionally substituted with one or more substituents chosen among -OH, the halogen atoms (Cl, Br, I and F), and the groups -Si (R ' ₄ R' ₅ R ' ₆ ) and -Si (R' ₄ R ' ₅ ) O, in which R '4, R' 5 and R _'5, identical or different, represent a hydrogen atom, an alkyl group -C ₆ or phenyl;

a group - (OC ₂ H ₄ ) _m -OR '', with m = 5 to 300 and R "= H or C 1 to C ₃₀ alkyl, for example - (OC ₂ H ₄ ) _m -

OH, - (OC ₂ H ₄ ) _m -O-methyl or - (OC ₂ H ₄ ) _m -O-behenyl; a group - (OC ₃ H ₆ ) _m -OR ", with m = 5 to 300 and R" = H or C 1 to C ₃₀ alkyl, for example - (OC ₃ H ₅ ) _m -OH, or statistical mixture or block of groups (OC ₂ H ₄ ) _m and

(OC ₃ H ₅ ) _m .

Examples of such additional monomers are (meth) acrylamide, N-ethyl (meth) acrylamide, N-butylacrylamide, N-t-butylacrylamide,

N-isopropylacrylamide, N, N-dimethyl (meth) acrylamide, N, N-dibutylacrylamide, N-octylacrylamide,

N-dodecylacrylamide, N-undecylacrylamide, and N-

(2-hydroxypropylmethacrylamide). (iv) the vinyl compounds of formula:

CH ₂ -CH R ₉ wherein R ₉ is a hydroxyl group; a halogen (Cl or F); an NH ₂ group; a group -OR ₀ wherein Rio represents a phenyl group or an alkyl group Ci-Ci ₂ (the monomer is a vinyl or allylic ether); an acetamide group (NHCOCH ₃ ); OCORn a group wherein Rn represents an alkyl group of 2 to 12 carbons, linear or branched (the monomer is a vinyl ester or allyl), cycloalkyl C ₃ -C ₂ aryl, C ₃ -C ₂₀ or in arallyle C ₄ -C ₃₀ ; or else R ₉ is chosen from: a linear or branched alkyl group comprising from 1 to 30 carbon atoms, in which one or more heteroatoms chosen from O, N, S and P are optionally intercalated; said alkyl group may further be optionally substituted by one or more substituents selected from -OH, halogen atoms (Cl, Br, I and F), and -Si groups;

(R ' ₄ R' ₅ R ' ₆ ) and -Si (R' ₄ R ' ₅ ) O, wherein R' ₄ , R 's and

R '5, identical or different, represent a hydrogen atom, an alkyl group -C ₆ or phenyl;

a C ₃ to C ₁₂ cycloalkyl group such as an isobornyl or cyclohexane group,

a C ₃ to C ₂ aryl group such as a phenyl group,

a C ₄ -C ₃₀ arylalkyl or alkylaryl group (C ₁ -C ₈ alkyl group) such as a 2-phenylethyl or benzyl group,

a heterocyclic group of 4 to 12 members containing one or more heteroatoms chosen from O, N and S, the ring being aromatic or not, such as N-vinylpyrrolidone and N-vinylcaprolactam;

a heterocycloalkyl (alkyl of 1 to 4 carbon atoms) group, such as a furfurylmethyl or tetrahydrofurfurylmethyl group, said cycloalkyl, aryl, aralkyl, heterocyclic or heterocycloalkyl groups possibly being substituted by one or more substituents chosen from hydroxyl groups, halogen atoms, and alkyl groups from 1 to 4 linear or branched carbon atoms in which is optionally intercalated one or more heteroatoms selected from O, N, S and P, said alkyl groups may further be optionally substituted with one or more substituents selected from -OH, the halogen atoms

(Cl, Br, I and F) and the groups -Si (R ' ₄ R' ₅ R ' ₅ ) and -Si

(R ' ₄ R' ₅ ) O, wherein R '4, R' 5 and R '5, which may be identical or different, represent a hydrogen atom, a C ₁ -C ₆ alkyl group, or a phenyl group.

Examples of such additional monomers are vinylcyclohexane, and styrene (hydrophobic); N-vinylpyrrolidone and N-vinylcaprolactam (non-ionic hydrophilic); vinyl acetate, vinyl propionate, vinyl butyrate, vinyl ethylhexanoate, vinyl neononanoate and vinyl neododecanoate (hydrophobic); vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether. (v) the allylic compounds of formula:

CH ₂ = CH-CH ₂ -R ₉ or CH ₂ = C (CH ₃ ) -CH ₂ -R ₉ wherein R ₉ has the same meaning as above.

There may be mentioned in particular allyl methyl ether, 3-allyloxy-1,2-propanediol (CH ₂ = CHCH ₂ OCH ₂ CH (OH) CH ₂ OH) and 2-allyloxyethanol (CH ₂ = CHCH ₂ OC ₂ H ₄ OH ).

(vi) (meth) acrylic monomers,

(meth) acrylamides or vinylic silicones, such as methacryloxypropyltris (trimethylsiloxy) silane or

Acryloxypropylpoly-dimethylsiloxane, or silicone (meth) acrylamides. Among the additional monomers (particularly hydrophilic nonionic) more particularly preferred, mention may be made, alone or as a mixture, of the following monomers for which the Tg is given in parenthesis as an indication:

hydroxyalkyl (meth) acrylates and (meth) acrylamides in which the alkyl group comprises 2 to 4 carbon atoms, in particular 2-hydroxyethyl acrylate (Tg = 15 ^° C.) and 2-hydroxyethyl methacrylate; (55 ^° C.), 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, N- (2-hydroxypropyl) (meth) acrylamide;

- (meth) acrylates and (meth) acrylamides of alkoxy (Cl- ₄₎ alkyl (Cl- ₄₎ such as (meth) acrylates and (meth) acrylamides methoxyethyl, 2-ethoxyethyl, methoxypropyl and di- (2-ethoxyethyl); more particularly 2-ethoxyethyl methacrylate; (meth) acrylamide and N, N-dimethylacrylamide;

(meth) acrylates and (meth) acrylamides having - (OC ₂ H ₄ ) _m -OR 1 'group, with m = 5 to 300 and, R "= H or C 1 to C ₄ alkyl, for example the (meth) acrylates and polyethylene glycol (methoxy- or hydroxy-terminated) (meth) acrylamides, and more particularly hydroxy-terminated polyethylene glycol methacrylate (n = 8, 10, 12, 45, 90 or 200) and polyethylene glycol methacrylate methoxy terminated (n = 8, 10, 12, 45, 90 or 200) (Tg = -55 ⁰ C). vinyllactams such as vinylpyrrolidone and vinylcaprolactam;

vinyl ethers such as vinyl methyl ether (Tg = -34 ^° C.) and vinyl ethyl ether; vinylacetamide, N-vinylpyrrolidone, N-vinylcaprolactam;

polysaccharide (meth) acrylates such as sucrose acrylate and ethylglucoside (meth) acrylate. Mention may also be made, among the additional monomers (in particular hydrophobic) which are more particularly preferred, alone or as a mixture, for the following monomers for which the Tg is given in parenthesis by way of indication: t-butylbenzyl acrylate, acrylate t-butylcyclohexyl, isobornyl acrylate (94 ^° C.), furfuryl acrylate, n-hexyl acrylate (45 ^° C.), t-butyl acrylate (50 ^° C.), and cyclohexyl acrylate (19 ^° C.), hydroxyethyl acrylate (15 ^° C.), methyl acrylate (10 ^° C.), ethyl acrylate

(-24 ⁰ C), isobutyl acrylate (-24 ⁰ C), methoxyethyl acrylate (-33 ⁰ C), n-butyl acrylate (-54 ⁰ C), acrylate ethylhexyl (-50 ^° C.), hexyl acrylate, octyl acrylate, lauryl acrylate, isooctyl acrylate, isodecyl acrylate;

t-butylbenzyl methacrylate, t-butylcyclohexyl methacrylate, isobornyl methacrylate (111 ^° C.) and methyl methacrylate

(100 ^° C.), cyclohexyl methacrylate (83 ^° C.), ethyl methacrylate (65 ^° C.), benzyl methacrylate (54 ^° C.), isobutyl methacrylate (53 ^° C.), butyl methacrylate (20 ^° C.), n-hexyl methacrylate (-5 ^° C.), ethylhexyl methacrylate, octyl methacrylate, lauryl methacrylate, isooctyl methacrylate, isodecyl methacrylate ; styrene (100 ^° C.), vinylcyclohexane, vinyl acetate (23 ^° C.), vinyl methyl ether (-34 ^° C.), vinyl neononanoate, and vinyl neododecanoate;

N-butylacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide, N, N-dibutylacrylamide, N-t-butylacrylamide and N-octylacrylamide.

According to one embodiment of the invention, the B sequence may consist of monomeric units derived from nonionic and / or hydrophobic hydrophilic monomers as defined above. This sequence may also comprise -CO ₂ H functions generally resulting from the synthesis reaction of the block copolymer. According to a preferred embodiment of the invention, the copolymers of the invention are triblock copolymers, generally of ABC type, the sequences A, B and C corresponding to the same definition as that given above. Advantageously, the sequence B is present in a content ranging from 5 to 95% by weight of the copolymer, preferably in a content of greater than 50% by weight of the copolymer.

According to one embodiment, the sequence A and / or C comprises: monomeric units derived from nonionic monomers chosen from:

the vinyl compounds of formula CH ₂ = CH-R ₉ , R ₉ being as defined above, such as styrene;

methacrylate compounds of formula: R ₂

H ₂ C = C COOR ₃ with R ₂ and R ₃ being as defined above, such as methyl methacrylate; and monomeric units bearing at least one -CO ₂ H function derived from monomers chosen from acrylic acid and methacrylic acid.

The monomer units derived from nonionic monomers are present, for example, in a content ranging from 1 to 99.5% relative to the total weight of the sequence.

The monomeric units carrying at least one -CO ₂ H function are present, for example, in a content ranging from 0.5% to 99% relative to the total weight of the sequence.

According to one embodiment, the sequence B comprises monomer units derived from monomers chosen from (meth) acrylates of formula:

R ₂

H ₂ C = C COOR ₃ with R ₂ and R ₃ being as defined above.

Monomers within this definition and can advantageously enter the constitution of sequence B include n-hexyl methacrylate (Tg = -5 ° C), ethyl acrylate (Tg = -24 ° C), isobutyl acrylate (Tg = -24 ° C), n-butyl acrylate (Tg = -54 ° C), ethylhexyl acrylate (Tg = -50 ° C).

In particular, the sequence B may consist of monomeric units derived from n-butyl acrylate.

Triblock copolymers according to the invention may be chosen from poly (styrene-co-methacrylic acid) -b-poly (n-butyl acrylate) -b-poly (styrene-co-methacrylic acid), poly (methacrylate) methyl-co-methacrylic acid) -b- poly (n-butyl acrylate) -b-poly (methyl methacrylate-co-methacrylic acid).

More specifically, a particular poly (styrene-co-methacrylic acid) -b-poly (n-butyl acrylate) -b-poly (styrene-co-methacrylic acid) copolymer is that for which: the poly (acrylate) block n-butyl) represents 70% by weight of the total copolymer;

the poly (styrene-co-methacrylic acid) sequences each comprise monomeric units derived from methacrylic acid in a proportion of 2% by weight of the total copolymer and monomeric units derived from styrene at a rate of 12.5% by weight of the total copolymer;

a weight average molecular weight of 372,000 g. mol. ^1. Poly (methyl methacrylate-co-methacrylic acid) -b-poly (n-butyl acrylate) -b- copolymer poly (methyl methacrylate-co-methacrylic acid) is that for which:

the poly (n-butyl acrylate) block represents 35% by weight of the total copolymer; the poly (methyl methacrylate-co-methacrylic acid) sequences each comprise monomeric units derived from methacrylic acid in a proportion of 3.25% by weight of the total copolymer and of monomeric units derived from methyl methacrylate at 29%; 25% by weight of the total copolymer;

a weight average molecular weight of 150,000 g. mol ^"1 .

Another poly (methyl methacrylate-co-methacrylic acid) -b-poly (n-butyl acrylate) -b-poly (methyl methacrylate-co-methacrylic acid) copolymer is that for which:

the poly (n-butyl acrylate) block represents 65% by weight of the total copolymer;

the poly (methyl methacrylate-co-methacrylic acid) sequences each comprise monomeric units derived from methacrylic acid in a proportion of 1.6% by weight of the total copolymer and of monomeric units derived from methyl methacrylate at a concentration of 9% by weight of the total copolymer; a weight average molecular weight of

95,000 g. mol ^"1 .

The weight average molecular weight Mw of the block copolymer according to the invention is preferably greater than 10,000 g / mol, preferably greater than 50000 g / mol and less than 500 000 g / mol, preferably less than 300 000 g / mol. mol. Advantageously, the weight average molecular weight Mw of each block or block is between 5000 g / mol and 200,000 g / mol, preferably between 10,000 g / mol and 100,000 g / mol.

In order to be able to modulate the physical properties of the copolymers of the invention, it is possible to modify the degree of neutralization of the acid functions of the copolymers of the invention.

For this, the -CO ₂ H acid functions can be neutralized, advantageously, with mineral bases chosen from:

alkali hydroxides, such as LiOH, NaOH, KOH;

alkaline earth metal hydroxides, such as Ca (OH) ₂ ;

hydroxides of metals, such as zinc hydroxide, zinc acetate, iron hydroxide, copper hydroxide;

hydroxides of metalloids such as aluminum hydroxide.

The acid functions can also be neutralized with organic bases such as amines, in particular amines having a boiling point greater than 200 ^° C. under 1 atmosphere. Possible amines include primary, secondary or tertiary alkylamines, especially triethylamine or butylamine. This primary, secondary or tertiary alkylamine may comprise one or more nitrogen and / or oxygen atoms and may therefore for example include one or more alcohol functions; mention may especially be made of 2-amino-methyl-2-propanol, triethanolamine and dimethylamino-2-propanol. We can also mention lysine, 3- (dimethylamino) propylamine, urea.

This neutralization rate can be chosen judiciously according to the desired properties.

The degree of neutralization, corresponding to the ratio between the number of moles of acid function present in one kilogram of the copolymer and the number of moles of basic functions mixed per kilogram of polymer, is advantageously greater than 0.1, preferably greater than at 0.5. Said polymers may be prepared according to methods known to those skilled in the art. Among these methods, mention may be made of anionic polymerization; controlled radical polymerization, for example by xanthans, dithiocarbamates or dithioesters; polymerization using nitroxide precursors; radical transfer polymerization (ATRP); group transfer polymerization.

For example, the block copolymers according to the invention may be obtained by so-called controlled living radical polymerization or pseudo-living polymerization, described in particular in "New Method of Polymer Synthesis", Blackie Academy & Pro fesional, London, 1995, Volume 2, page 1. Controlled radical polymerization refers to polymerizations for which the Secondary reactions that usually lead to the disappearance of propagating species (termination or transfer reaction) are made very unlikely compared to the propagation reaction by a free radical control agent. The imperfection of this mode of polymerization lies in the fact that when the concentrations of free radicals become important with respect to the concentration of monomer, the secondary reactions become again decisive and tend to widen the distribution of the masses.

For the record, we recall that the living or pseudo-living polymerization is a polymerization for which the growth of the polymer chains ceases only with the disappearance of the monomer. The number average mass (Mn) increases with the conversion. Such polymerizations lead to copolymers whose mass dispersity is low, that is to say polymers with a mass polydispersity index (Ip) generally less than 2.

Anionic polymerization is a typical example of living polymerization.

Pseudo-living polymerization is, in turn, associated with controlled radical polymerization. Among the main types of controlled radical polymerization are:

the radical polymerization controlled by nitroxides. It is particularly possible to refer to the patent applications WO96 / 24620 and WO00 / 71501 which describe the tools of this polymerization and their implementation, as well as to the articles published by Fischer (Chemical Reviews, 2001, 101, 3581), by Tordo and Gnanou (J. Am Chem Soc 2000, 122, 5929) and Hawker (J. Am Chem Soc 1999, 121, 3904);

the radical atom transfer polymerization, in particular described in the application

WO96 / 30421 and which proceeds by the reversible insertion on an organometallic complex in a carbon-halogen type bond;

controlled radical polymerization with sulfur derivatives of the xanthate type, dithioesters, trithiocarbonates or carbamates, as described in the applications FR2821620, WO98 / 01478, WO99 / 35177, WO98 / 58974, WO99 / 31144, WO97 / 01478 and in the publication from Rizzardo & al. (Macromolecules, 1998, 31, 5559).

Thanks to these modes of polymerization, the polymer chains of the copolymers grow simultaneously and therefore incorporate at each instant the same ratio of comonomers. All chains therefore have the same structures or similar structures, resulting in low compositional dispersity. These chains also have a low mass polydispersity index.

Thus, the polymerization can be carried out according to the atom transfer technique (Atom Transfer Radical Polymerization or "ATRP", in English), or by reaction with a nitroxide, or even according to the technique of "reversible addition- fragmentation chain transfer "(" RAFT ") or finally by the technique of" reverse ATRP ", known as" reverse ATRP ". The atom transfer radical polymerization technique consists in blocking the growing radical species in the form of a C-halide bond (in the presence of metal / ligand complex). This type of polymerization results in a control of the mass of the polymers formed and a low index of dispersity of the masses. In general, atom transfer radical polymerization is carried out by polymerization of one or more radically polymerizable monomers, in the presence of:

an initiator having at least one transferable halogen atom;

a halogen compound comprising a transition metal capable of participating in a reduction step with one initiator and a "dormant" polymer chain, this will be called a "chain transfer agent"; and

a ligand that can be chosen from compounds comprising a nitrogen atom (N), oxygen

(0), of phosphorus (P) or of sulfur (S), capable of being coordinated by a bond σ to said compound comprising a transition metal, the formation of direct bonds between said compound comprising a transition metal and the polymer in formation being avoided.

The halogen atom is preferably a chlorine or bromine atom.

This process is in particular described in the application WO 97/18247 and in the article of Matyjasezwski et al. published in JACS, 117, page 5614 (1995).

The technique of radical polymerization by reaction with a nitroxide consists in blocking the growing radical species in the form of a CO-NRaR type bond where Ra and Rb can be, independently of one another, an alkyl radical having 2 to 30 carbon atoms or both forming, with the nitrogen atom, a ring having from 4 to 20 carbon atoms, such as for example a 2, 2, 6, 6-tetramethylpiperidinyl ring. This polymerization technique is described in particular in the articles "Living free radical polymerization: a unique technique for preparation of controlled macromolecular architectures" CJ Hawker; Chem. Res. 1997,30,373-82, and "Macromolecular engineering via living free radical polymerizations" published in Macromol. Chem. Phys. 1998, vol. 199, pages 923-935, or else in application WO-A-99/03894. The RAFT polymerization technique

(reversible addition-fragmentation chain transfer) consists in blocking the growing radical species in the form of a CS type bond. Dithio compounds such as dithioesters (-C (S) S-) are used for this purpose, such as dithiobenzoates, dithiocarbamates (-NC (S) S-) or dithiocarbonates (-OC (S) S-) (xanthates). ). These compounds make it possible to control the growth of the chain of a wide range of monomers. However, the dithioesters inhibit the polymerization of the vinyl esters, whereas the dithiocarbamates are very weakly active towards the methacrylates, which limits to a certain extent the application of these compounds. This technique is described in particular in the Rhodia application WO-A-98/58974 and in the article "A more versatile route to block copolymers and other polymers of complex architecture by living radical polymerization: the RAFT process", published in Macromolecules, 1999, vol. 32, pp. 2,071-2,074. WO-A-98/58974 already cited and WO-A-99/31144 of CSIRO relate to the use of dithiocarbamates as "RAFT" reagents. .

By varying the ratio of the monomer concentration to the chain transfer agent concentration, the molecular weight of the polymer can be varied.

The polymerization generally takes place in several steps according to the following general scheme:

a) in a first step, the polymerization of the first monomer or monomer mixture is carried out to form a macroinitiator or precursor;

b) the polymers can be purified by precipitation and then dried under vacuum,

c) in a second step, the polymerization of the second block consisting of a monomer or a mixture of monomers at the end of the macroinitiator is carried out.

Steps b and c are repeated as many times as necessary depending on the number of sequences, which is the case for the production of triblock polymers of ABC type or multiblock (ABC) n with A, B and

C being as defined previously. In the usual way, to produce symmetrical triblock polymers of the ABA or BAB type, a difunctional initiator is generally employed.

The chain transfer agents and solvents may be identical or different in step a) and step b).

The block or block polymers according to the invention can also be obtained by using the conventional radical polymerization technique by sequentially casting the monomers. In this case, only the control of the nature of the sequences is possible (no control of the masses).

It is a question of initially polymerizing a monomer M1 in a polymerization reactor; to follow, for example by kinetics, its consumption over time and then when M1 is consumed at about 95% then to introduce a new monomer M2 into the polymerization reactor. Thus, a block structure polymer of the M1-M2 type is easily obtained.

As mentioned above, the copolymers can have their physical properties (such as modulus of elastic shear, temperature resistance) modulated. It is therefore quite natural that the polymers of the invention find their application in the field of adhesives and the field of thermoplastic compositions.

Thus, the invention also relates to a composition comprising at least 1% by weight, relative to the total weight of the composition, of a copolymer as defined above. In particular, the composition may be an adhesive composition. In this case, the copolymer is present, advantageously, in a content of at least

5% by weight relative to the total weight of the composition.

The adhesive composition may include additives such as tackifying resins, plasticizers, such as oils, in which case it will be a hot melt pressure sensitive adhesive composition (known by the abbreviation HMPSA).

Without wishing to be bound by theory, the glass transition temperature of an HMPSA composition will be controlled by the glass transition temperatures of the soft phase of the copolymer (i.e., in our case, the phase having a Tg less than 15 ⁰ C), resin and oil (fulfilling the function of plasticizer) and their respective mass fractions in the soft phase according to a law of the type:

1 ^W rreess m moouu M

+ ™> mmnoutι W

+ soft oil

Where: w is the fraction by weight of the Tg block less than 15 ⁰ C of the copolymer; The soft fraction is the fraction by weight of resin incorporated in the low Tg phase (less than 20 ^° C.). The soft oil is the fraction by weight of oil incorporated in the low Tg phase (less than 20 ^° C.). Tg res is the glass transition temperature of the resin measured at the stress frequency of 1 Hz

Tg oil is the glass transition temperature of the oil measured at the stress rate of 1 hz on the pure model copolymer;

Soft Tg is the glass transition temperature of the low Tg block (i.e. less than 15 ⁰ C, in our case) of the type measured at the stress frequency of 1 Hz on the pure model copolymer.

In order for the composition to have adhesive properties at room temperature, it will be particularly important that the glass transition temperature be below room temperature.

In the present invention, we have found that neutralization does not alter the glass transition temperature of the copolymer, hence of a final adhesive composition. This makes it possible to control the elastic modulus of the product or formulation without increasing its glass transition temperature, as is most often the case.

By using the neutralization of the copolymer, it will thus be possible to change the modulus of the final adhesive composition and thus its application segments while having essentially used the same raw materials.

Similarly, in adhesive compositions, a very important property relates to the behavior of the adhesive temperature. This behavior is usually characterized by the SAFT test (or PAFT). SAFT measures the ability of a hot melt adhesive to withstand a static force of 500 g (or 100 g) in shear (or peel) under a steady temperature rise of 0.4 ° C / min. It is therefore clear to one skilled in the art that the SAFT of a given composition will be related to its ability to maintain its modulus level, at low deformation rate as encountered in creep, over the temperature range. bigger. Generally, the oils to be used as plasticizers in HPSA compositions are trimellitate type oils, such as trioctyl trimellitate, or even predominantly naphthenic oils such as Catenex N956 from Shell. It is disadvised to use oils of paraffinic type (typically Primol 352 oil, Exxon-Mobil), liquid polybutene type (typically Napvis 10) because, under certain conditions, they are incompatible with the copolymer and exude from the mixture. According to the invention, the tackifying resins are generally resins based on collophanes such as Forai AX, rosin ester such as Forai F85, resins known under the name pure monomer such as Krystallex F85, polyterpenes such as DERCOLYTE A 115 from DRT, hydroxylated polyesters (typically Reagem 5110 from DRT), terpene styrene (typically DERCOLYTE TS 105 from DRT), terpene pentaerythritol (typically DERTOLINE P2L), terpene phenol-based resins (typically Dertophene). T105 from DRT). The composition of the invention can be used as an adhesive, to constitute, for example, strips, labels and adhesive tapes, in various fields, such as hygiene, wood, binding, packaging.

The invention also relates to the use of a copolymer as defined above as a hot melt adhesive.

The compositions of the invention may also be thermoplastic compositions. As additives, such compositions may further comprise one or more thermoplastic polymers, such as polymethyl methacrylate, polystyrene and polyvinyl chloride. By using the copolymers of the present invention, it will be possible to control the level of modulus of a given copolymer by the level of neutralization of the reactive monomers.

This control of the level of the module can be done without increasing the glass transition temperature of the elastomer domains, which will make it possible to retain the impact-enhancing contribution provided by these domains. On the other hand, the use of the present invention will advantageously increase the temperature stability of the thermoplastic phase of the copolymer. This will lead to improved properties when the product is used in applications that expose it to high temperatures, such as in the field of luminaires. In addition, it will also be possible to provide the polymer with improved properties of creep resistance by increasing its low shear rate viscosity. This is a great advantage for parts subjected to long-term stresses such as pipes or pipes.

Thus parts may be injected, molded, rolled, extruded thermoformed which will have excellent mechanical and thermal resistance during their application (glazing, Fresnel lens for projector, composition for uses near a heat source such as a automotive engine).

Whether for adhesive compositions or thermoplastic compositions, they generally comprise a mineral or organic base as defined above, so as to neutralize all or part of the CO ₂ H acid functional groups, with a view to modulating the physical properties. of said composition. The compositions comprising copolymers according to the invention neutralized in whole or in part may be prepared by liquid, in which case the process comprises a step of contacting the copolymer with a mineral or organic base in a liquid medium, or by melting, in which case the process comprises a step of melting the copolymer with a mineral or organic base.

The invention will now be described with reference to the following examples given for illustrative and non-limiting. BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1 to 15 illustrate, in graphic form, the effect of the neutralization of copolymers of the invention on the physical properties thereof.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

In order to expose the examples above, we define the following methods and tests implemented in the context of these examples.

1) Braebander mix

The various mixtures in the molten state which are presented in the examples below are made on a RHEOCORD micromaxer whose mixing chamber is 66 cm ³ . The mixing conditions, temperature and speed, are suitable for mixing and will be specified in the examples. During mixing, it is possible to record the torque provided by the rotors during mixing, a very useful data since it is related to the viscosity of the product under the conditions of the experiment.

2) DMTA measurement (or DMA)

DMTA (or DMA) is a method of analysis that measures the viscoelastic properties (G ', G'', tan d, eta *, ...) of a product as a function of temperature. at the given bias frequency, of 1 Hz in our examples. We specify that the quantities G ', G'', tan d and eta * respectively correspond to the elastic modulus, the loss modulus (in Pa), the ratio (G''/G') and the viscosity (in Pa / s). These measurements are performed on an ARES rheometer of Rheometrics Scientific.

3) Measurement of capillary rheology

The capillary rheology measurements are carried out on a ROSAND RH7 double sheath rheometer by applying the Bagley and Rabinowitch corrections known to those skilled in the art. These measurements made on a product in the molten state make it possible to characterize the behavior of a product at a given temperature at high shear gradients, such as those usually encountered during the use of plastics or adhesive formulations. .

4) Dynamic viscoelasticity measurement

The dynamic viscoelasticity measurements are carried out on an ARES viscoelasticimeter of

Rheometrics Scientific in plane / plane geometry 25 mm. The viscoelastic properties of a product are determined as a function of the dynamic stressing frequency at a given temperature.

5) Tensile measurement

The tensile measurements are carried out at ambient temperature at a traverse speed of 50 mm / min on an ADAMEL LHOMARGY DY 30 machine according to ISO 527-2.

Cutting of the specimens is done using a charly robot driven milling machine on the model of 5A specimens. A minimum of 5 tests is performed for each product.

From the geometry of the sample, the Young's modulus E of the material is determined by taking the slope at the origin of the stress curve = f (strain) on an average of tests per product.

EXAMPLE 1

Preparation of the Poly (styrene-co-methacrylic acid) copolymer b-poly (n-butyl acrylate) -b-poly (styrene-co-methacrylic acid), denoted PRC302.

In a 500 mL reactor equipped with a variable speed stirring motor, inputs for the introduction of reagents, taps for the introduction of inert gases for the removal of oxygen, such as nitrogen, and measurement probes (eg, temperature), a jacket for heating / cooling the reactor contents through the circulation therein, of a coolant, is introduced 136 g of n-butyl acrylate 3.47 g of a solution of 1,6-di [2- (N-tert-butyl-N- (1-diethylphosphono-2,2-dimethylpropyl) -N-oxyl) propionate] hexylene alkoxyamine, noted " DIAMS "of following formula:

to 20% by weight in ethylbenzene and 0.375 g of a solution of N-tert-1-diethyl phosphono-2, 2-dimethylpropyl nitroxide denoted "SGl" of formula:

to 10% by weight in ethylbenzene. The reaction medium is then brought to 114 ^° C., and this temperature is maintained for 6 hours until a conversion of n-butyl acrylate is obtained.

(Abu) of the order of 70%. The residual monomer is then removed at 75 ^° C. under 200-300 mbar. The molecular weights of n-butyl polyacrylate in SEC-equivalent polystyrene equivalents are 90 140 g / mole for the mass at the peak of the distribution (Mp), 57 730 for the number average molecular weight (Mn), 89 650 for the weight average molecular weight (Mw) and a polymolecularity index of 1.6. In a second synthesis step, 133 g of toluene, 35 g of styrene (S) and 6 g of methacrylic acid (AMA) are introduced into the reactor. containing the previously synthesized n-butyl polyacrylate. After degassing with nitrogen, the temperature is adjusted to 12O ⁰ C and maintained for 4 hours. After devolatilization of the residual monomers and solvent, followed by a granulation step, the poly (styrene-co-methacrylic acid) b-poly (n-butyl acrylate) -b-poly (styrene-co-methacrylic acid) copolymer is recovered in the form of granules. The chemical composition of the copolymer obtained, expressed as a percentage by mass, is the following: PAbu / P (S, AMA): 70/30 (86.14). The molecular weights of the copolymer in polymethyl methacrylate equivalent determined by SEC are 372,280 g / mole for the weight average molecular weight (Mw). Characteristics of PRC302 P (S / AMA) -PABu-P (S / AMA): Mw = 372,000 g.mol-1, IP 6.7, Composition: (12.5% S - 2% AMA) - 71% Abu - (12.5 % S - 2% AMA)

EXAMPLE 2 Preparation of the copolymer poly (methyl methacrylate-co-methacrylic acid) -b-poly (n-butyl acrylate) -b-poly (methyl methacrylate-co-methacrylic acid), denoted DC59

In a 20 L reactor equipped with a variable speed stirring motor, inputs for the introduction of reagents, taps for the introduction of inert gases for the removal of oxygen, such as nitrogen, and measurement probes (eg, temperature), a double jacket for heating / cooling the contents of the reactor through the circulation therein, a heat transfer fluid, Introduced 11 kg of n-butyl acrylate, 154 g of 1,6-di [2- (N-tert-butyl-N- (1-diethylphosphono-2,2-dimethylpropyl) -N-oxyl) alkoxyamine. propionate] hexylene denoted "DIAMS" (ARKEMA) and 10.8 g of N-tert-1-diethyl phosphono-2, 2-dimethylpropyl nitroxide noted "SGl" (ARKEMA). The reaction medium is then brought to 117 ^° C., and this temperature is maintained for 6 hours until an n-butyl acrylate conversion level of about 60% is reached. The residual monomer is removed at 75 ^° C. under 200-300 mbar. The n-butyl polyacrylate is then diluted in 5.9 kg of toluene, and the toluene solution is drained from the reactor. The molecular weights of n-butyl polyacrylate in SEC-equivalent polystyrene were 52,726 g / mole for the mass at the peak of the distribution (Mp), 46,100 for the number average molecular weight (Mn), 109 000 for the weight average molecular weight (Mw) and a polymolecularity index of 2.4. In a second synthesis step, 5 kg of toluene toluene solution of previously prepared n-butyl polyacrylate, 4 kg of toluene, 8.01 kg of methyl methacrylate and 0.9 kg of methacrylic acid are introduced into the reactor. After degassing with nitrogen, the temperature was adjusted to 100 ⁰ C for hour 30 minutes, then at 12O ⁰ C for lh30. After devolatilization of the residual monomers and solvent, followed by a granulation step, the copolymer P (MMA / AMA) -PABu-P (MMA / AMA) is recovered in the form of granules. The chemical composition of the copolymer obtained, expressed as a percentage by weight, is as follows: PAbu / P (MMA, AMA): 35/65 (90,10). The molecular weights of the polymethyl methacrylate equivalent copolymer determined by SEC are 123 100 g / mol for the mass at the peak of the distribution (Mp), 75 620 for the number average molecular weight (Mn), 153 300 for the weight average molecular weight (Mw) and a polymolecularity index of 2.0.

Characteristics of DC59 (MMA-AMA) -Abu- (MMA-AMA): Mw = 150,000 g.mol-1, Composition: (29.25% MMA - 3.25% AMA) - 35% ABu - (29.25% MMA - 3.25% AMA)

EXAMPLE 3

Preparation of the copolymer poly (methyl methacrylate-co-methacrylic acid) -b-poly (n-butyl acrylate) -b-poly (methyl methacrylate-co-methacrylic acid), denoted PIL 0407

In a 20 L reactor equipped with a variable speed stirring motor, inputs for the introduction of reagents, taps for the introduction of inert gases for the removal of oxygen, such as nitrogen, and measuring probes (eg, temperature), a double jacket for heating / cooling the reactor contents through the circulation therein, a heat transfer fluid is introduced 11 kg of n-butyl acrylate 154 g of 1,6-di [2- (N-tert-butyl-N- (1-diethylphosphono-2,2-dimethylpropyl) -N-oxyl) propionate] hexylene alkoxyamine labeled "DIAMS" (ARKEMA) and 10 8 g of N-tert-1-diethyl phosphono-2, 2-dimethylpropyl nitroxide noted "SGl" (ARKEMA). The reaction medium is then brought to 117 ^° C., and this temperature maintained for 6 hours until reaching an n-butyl acrylate conversion of the order of 60%. The residual monomer is then removed at 75 ^° C. under 200-300 mbar. The n-butyl polyacrylate is then diluted in 5.9 kg of toluene, and the toluene solution is drained from the reactor. The molecular weights of n-butyl polyacrylate in SEC-equivalent polystyrene were 52,726 g / mole for the mass at the peak of the distribution (Mp), 46,100 for the number average molecular weight (Mn), 109 000 for the weight average molecular weight (Mw) and a polymolecularity index of 2.4.

In a second synthesis step, 5 kg of toluene solution of n-butyl polyacrylate, previously prepared, are introduced into the reactor.

4.78 kg of toluene, 1.87 kg of methyl methacrylate

(MMA) and 0.21 kg of methacrylic acid (AMA). After degassing with nitrogen, the temperature was adjusted to 105 ⁰ C for hour 30 minutes, then at 12O ⁰ C for lh30. After devolatilization of the residual monomers and solvent, followed by a granulation step, the copolymer P (MMA / AMA) -PABu-P (MMA / AMA) is recovered in the form of granules. The chemical composition of the copolymer obtained, expressed as a percentage by weight, is as follows: PAbu / P (MMA, AMA): 73/27 (90.10). The molecular weights of the copolymer in equivalent

Methyl polymethacrylate determined by SEC are

77 030 g / mole for the mass at the peak of the distribution

(Mp), 50,940 for the number average molecular weight (Mn), 95,240 for the molecular weight weight average (Mw) and a polymolecularity index of 1.9.

Characteristics of PIL 0407 PIL 0407 - (MMA-AMA) -Abu- (MMA-AMA): Mw = 95,000 gmol-1, Ip = I, 9, Composition: (15.9% MMA / 1.6% AMA) - 65 % PBA - (15.9% MMA / 1.6% AMA)

EXAMPLE 4

This example illustrates the effect of the solvent neutralization of the PRC 302 copolymer on the level of the elastic shear modulus G '.

The PRC copolymer 302 is dissolved in a solvent, for example THF, by adding a dilute solution of KOH in water so as to introduce an equivalent of OH- per acid functional equivalent of PRC302 (for example, to neutralize the presence of equivalent to 30 g of a copolymer containing 5% AMA, 0.97 g of KOH dissolved in approximately 5 g of water must be introduced). The mixture is stirred at ambient temperature for a few hours and then the solvents are evaporated first at 60 ^° C. and then when the bulk of the solvent is removed by placing the product in a vacuum oven at 120 ^° C. for 1 hour.

A sample of PRC302 is prepared equivalently without the introduction of base to neutralize the product.

The two products are analyzed in DMA as illustrated in FIG. 1, which represents the evolution of the elastic shear modulus G '(Pa) as a function of time ( ⁰ C) and also the evolution of tan d as a function of time. Table 1 below shows the increase of the elastic shear modulus on the neutralized PRC 302 in comparison with the unneutralized product.

In this example, it is clear to those skilled in the art that the level of the module G 'of the copolymer at room temperature has been improved without modifying the glass transition temperature of the low Tg phase. Mechanical strength illustrated by G 'increases without affecting the elastomeric properties of the material. The curves showing the evolution of G ', G''and tan d as a function of the temperature indicate that the resistance of the product in temperature to the low strain rates such as those used for the measurement between the control without neutralization and the product which has been neutralized with potassium hydroxide in solution. EXAMPLE 5

This example illustrates the effect of the solvent neutralization of the PRC 302 copolymer on the viscosity, the elastic shear modulus G ', the Young's modulus, and the low shear rate viscosification.

The PRC 302 copolymer is hot kneaded in Branbaender at the temperature of 18O ⁰ C for one hour with or without the introduction of KOH, the pellets were ground in powder form.

Figure 2 compares the evolution of the mixing torque for the product with KOH and for the control. Table 2 contains the various information on the mixtures used.

V corresponds to the speed of rotation of the rotors in the mixer and Tmax corresponds to the self-heating temperature caused by the shear phenomenon

It is clear to those skilled in the art that the difference in torque level recorded between the product with and without KOH is indeed due to an increase in viscosity following the neutralization by the base and not only to the addition of an additional charge. Figure 3 presents the DMA and the comparison of the elastic shear moduli for these two products.

The table groups the following results:

It can be noted, as on neutralization in solution, that neutralization in the molten state makes it possible to improve the level of the elastic shear modulus of the product at room temperature without modifying the glass transition temperature of the low Tg phase. It is also clear that the temperature resistance of the product has been considerably increased at low strain rates as used for the measurement.

It is also possible to highlight this effect of the neutralization by performing tensile measurements at room temperature on the samples. Figure 4 shows the tensile curve at 50 mm / min of the neutralized product compared to the unneutralized product. Table 4 shows the following results

It can be seen from this table that the increase in the Young's modulus is of the order of a factor of 6 after neutralization.

5 shows the capillary rheology 21O ⁰ C of the two products. Neutralization brings significant viscosification of the product at low shear gradients, but in high shear gradients such as those encountered in implementation the difference is smaller.

Example 6

It is possible to use various bases to carry out this neutralization which makes it possible to modulate the properties of the products of the invention.

Thus, it may be advantageous to use, for example, 2-amino-2-methylpropanol, which is a high-boiling point liquid (160 ^° C.) in place of KOH which is a high-melting solid. . We have also compared the use of zinc acetate.

Table 5 contains information on the various mixtures made.

The mixing torques as a function of time are illustrated in FIG. 6. These results clearly illustrate that the various bases make it possible to neutralize the reactive monomers of the copolymer.

Figure 7 shows the comparative DMAs of the different products and Table 6 illustrates the module increases.

As in the case of KOH, it will be possible to control the level of modulus of a given product without affecting the Tg of its soft phase and increasing its resistance to temperature. This is also illustrated in Figure 8.

Table 7 illustrates the following results.

It shows the evaluation of the tensile properties of the neutralized product with Zinc acetate: as in the case of DMA, there is a slight increase in the modulus of the product but less than in the case of potash.

Example 7

The same principle of being able to modulate the properties of a given copolymer using ionomers can be applied to all the copolymers claimed in the invention containing reactive groups. These may be "all acrylic" copolymers for PSA adhesive applications such as PIL 0407 or "all acrylic" copolymers for thermoplastic applications such as DC59.

Table 8 describes the melt blends made with these two copolymers.

* mix over 10 minutes

The effect of the neutralization on the mixtures with DC 59 is illustrated in FIGS. 9 and 10. FIG. 9 shows the mixing torques as a function of time and FIG. 10 shows the evolution of the material temperature as a function of time. On the mixtures with the bases, it is possible to see that the heating with respect to the target temperature due to the neutralization reaction and the viscosity increase of the product is much greater than that of the product without base. Figure 11 and Table 9 illustrate on PIL 0407 in comparison with the unmixed product the effect of the neutralization on the increase of the mechanical properties of the copolymer.

Table 9 summarizes the following results:

The neutralized copolymer not only has a double modulus at room temperature without having modified the Tg of the soft phase, which for a given HMPSA formulation would make it possible to obtain a product with a double modulus with respect to the same copolymer formulated without neutralization. But, this copolymer after neutralization also has a much better thermal stability as shown by its elastic modulus which varies very little with the temperature compared to the unneutralized product. This last is also found on the evolution of tan delta as a function of temperature: after neutralization, PiI 0407 shows a more elastic and less viscous behavior (tan delta level lower). All of these elements should lead to HMPSA formulations whose temperature resistance (or SAFT) will be improved over the unneutralized product.

In this example, it may also be noted that the neutralization at 18O ⁰ C seems more efficient than at 180 ^° C. (torque level during mixing in Table 8, module level in Table 9, tan d lower in the graph 11): the neutralization temperature may serve as another parameter in order to adapt the thermomechanical properties of a given product.

Example 8

We have seen that it is possible, through neutralization solvent or molten, to adapt the thermomechanical properties of a copolymer claimed in the invention.

It is also advantageous to be able to carry out this neutralization not only at the level of the pure copolymer but also at the level of the formulation of the copolymer.

By being able to achieve the neutralization during the mixing of the various components forming a pressure-sensitive hot melt, the formulator will be free to adapt the properties of its mixture to its application while having to deal with only one raw material . To illustrate this concept, we have chosen to produce a HMPSA formulation from the PRC 302 copolymer used at 70% with 30% of a mixture consisting of 20% of a plasticizer trioctyltrimelittate and 80% of a resin the Forai AX. The properties of a control mixture are compared with those of the same mixture neutralized with 1 equivalent of KOH or with 1 equivalent of 2-amino-2-methylpropanol.

The mixtures are made in Brabaender at 15O ⁰ C: the properties of the three mixtures are recalled in Table 10.

Figure 12 compares the mixture pairs in the Brabaender for the control product and HMPSA neutralized with 2-amino-2-methylpropanol. We have compared the rheological properties of the control formulation and the neutralized product with potash in capillary rheology at 160 ^° C. in Chart 13. The measurements are carried out at 160 ^° C. in capillary rheology with high shear gradients (eta = f ( shear gradient)) and dynamic viscoelasticity at low shear rate (eta * = f (stress frequency)) by applying the Cox-Merz principle well known to those skilled in the art. This example shows that if the viscosity at high shear gradients is slightly affected by the neutralization, the increase in viscosity and elasticity at low shear rate is much greater as shown in Figure 14 which is the ratio for each frequency (or shear rate) of the viscosity or elasticity of the neutralized formulation relative to the control formulation. This is an advantage for all applications where the creep resistance of the product will be brought into play.

The ^thermo¬ mechanical properties of the control formulation and of the formulation neutralized with 2-amino-2-methyl propanol or KOH in DMA were evaluated. The measurements are shown in Figure 15.

Table 11 illustrates the following results.

As shown in Table 11, the neutralization allows a module increase of the formulation whose amplitude can be controlled according to the base used. This increase is sensitive not only at ambient temperature but also at high temperatures, which makes it possible to improve the SAFT properties of a given formulation. This increase is obtained without increasing the Tg of the soft phase.

The neutralization will allow us to reduce the amount of polymer to obtain a formulation of a given module, and thus reduce the overall cost of the product. However, care must be taken to control the level of neutralization of the product: thus, in our example, we have made products that are quite tacky and very cohesive with a large proportion of polymer whose cohesion we have further strengthened by neutralization.

Claims

A linear, ethylenic, linear block copolymer comprising:

at least one first block A having a glass transition temperature greater than 20 ^° C .;

at least one second block B having a glass transition temperature below 15 ^° C .; at least a third C sequence having a glass transition temperature greater than 20 ^° C .; said first sequence A and third block C being identical or different and at least one of them comprising at least one monomeric unit comprising at least one -CO ₂ H and / or carboxylate -COO ^"function .

2. Copolymer according to claim 1, wherein the monomer unit comprising at least one -CO ₂ H and / or -COO ^"function is present in a content ranging from 0.5 to 99 mol%.

3. Copolymer according to claim 2, wherein the monomeric unit comprising at least one -CO ₂ H function is present in a content ranging from 3 to 30 mol%.

4. Copolymer according to any one of the preceding claims, wherein the first sequence A and / or the third sequence C has a glass transition temperature greater than 60 ^° C.

5. Copolymer according to any one of the preceding claims, wherein the second block B has a glass transition temperature below -30 ^° C.

6. Copolymer according to any one of the preceding claims, wherein the monomer unit comprising at least one -CO ₂ H function is derived from a monomer corresponding to the following formula (I):

(I) in which:

R 1 is a hydrogen atom or a linear or branched hydrocarbon group of type C _p H _{2p +} 1, with p being an integer ranging from 1 to 12;

Z is a divalent group selected from - COO-, -CONH-, -CONCH ₃ -, -OCO- or -O-; preferably -

COO- and -CONH-;

- x is 0 or 1;

R ₂ is a divalent carbon, saturated or unsaturated, optionally aromatic, linear, branched or cyclic group, comprising from 1 to 30 carbon atoms, which may comprise from 1 to 30 heteroatoms selected from O, N, S, and P;

m is an integer equal to 0 or 1.

7. Copolymer according to claim 6, wherein, in the formula (I), R 1 is a hydrogen atom or a methyl group, x is 0 and m is 0.

The copolymer of claim 6, wherein R ₂ is:

an alkylene group; - a phenylene group -C ₆ H ₄ - (ortho, meta or para), optionally substituted by alkyl, Ci-Ci ₂ optionally comprising 1 to 8 heteroatoms selected from 0, N, S, and P; or benzylene -C ₅ H ₄ -CH ₂ - optionally substituted by alkyl, Ci-Ci ₂ optionally comprising 1 to 8 heteroatoms selected from 0, N, S, and P;

a group of formula -CH ₂ -CHOH-, -CH ₂ -CH ₂ -CHOH-, -CH ₂ -CH ₂ -CH (NH ₂ ) -, -CH ₂ -CH (NH ₂ ) -, -CH ₂ -CH ₂ -CH (NHR ') -, -CH ₂ -CH (NHR') -, -CH ₂ -CH ₂ -CH (NR ¹ R ") -, -CH ₂ -CH (NR ¹ R") - , -CH ₂ -CH = CH- where R 'and R "representing a linear or branched Ci-Ci _8.

9. Copolymer according to any one of claims 1 to 5, wherein the unit comprising at least one -CO ₂ H function is derived from a monomer selected from acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, diacrylic acid, dimethylfumaric acid, citraconic acid, vinylbenzoic acid, acrylamidoglycolic acid of formula CH ₂ = CH-CONHCH (OH) COOH, diallyl maleate of formula C ₃ H ₅ -CO ₂ -CH = CH-CO ₂ -C ₃ H ₅ , butyl (meth) acrylate, carboxylic anhydrides carrying a vinyl bond, and their salts; and their mixtures.

10. Copolymer according to any one of claims 1 to 5, wherein the monomer unit comprising at least one carboxylate function -COO ^" is derived from an amphoteric monomer of formula (II) below:

(H) wherein:

R 1, Z, x, R ₂ and m have the same meanings as in formula (I) of claim 6;

X ¹⁺ is a divalent group of formula - N ⁺ R ' ₅ R' ₇ with R ' ₆ and RZ ₇ representing, independently of one another,

(i) a hydrogen atom; (ii) a linear, branched or cyclic, optionally aromatic, alkyl group comprising from 1 to 30 carbon atoms, which can comprise from 1 to 8 heteroatoms selected from O, N, S and P;

(iii) an alkylene oxide group of formula - (R ' ₈ O) _y R' ₉ with R ' ₈ representing a linear or branched C ₂ -C ₄ alkyl group, R' ₉ is hydrogen or a group linear or branched C 1 -C ₃₀ alkyl and y is an integer from 1 to 250; (iv) R ' ₅ and R' 7 may form with the nitrogen atom a saturated or unsaturated, optionally aromatic ring (NR ' ₅ R' ₇ or R ' ₅ NR' ₇ ) comprising in total 5, 6, 7 or 8 atoms, and especially 4, 5, 6 or 7 carbon atoms and / or 2 to 4 heteroatoms selected from 0, S and N; said cycle being fusible with one or more other rings, saturated or unsaturated, optionally aromatic, each comprising 5, 6, 7 or 8 atoms, and in particular 4, 5, 6 or 7 carbon atoms and / or 2 to 4 selected heteroatoms among 0, S and N;

R ₃ is a divalent carbon, saturated or unsaturated, optionally aromatic, linear, branched or cyclic group, of 1 to 30 carbon atoms, which can comprise 1 to 18 heteroatoms chosen from O, N, S and P;

- n is 0 or 1.

The copolymer of claim 10, wherein R ₃ is:

an alkylene group;

- a phenylene group -C ₆ H ₄ - (ortho, meta or para), optionally substituted by alkyl, Ci-Ci ₂ optionally comprising 1 to 5 heteroatoms selected from 0, N, S, F, Si and P; or benzylene group -C ₆ H ₄ -CH ₂ - optionally substituted by alkyl, Ci-Ci ₂ optionally comprising 1 to 5 heteroatoms selected from 0, N, S and P.

The copolymer according to any one of the preceding claims, wherein the first sequence A and / or the third block C comprises, in addition, one or more monomer units derived from additional monomers chosen from hydrophilic nonionic monomers, hydrophobic monomers and mixtures thereof.

13. Copolymer according to claim 12, wherein the additional monomer is chosen from, alone or as a mixture: (i) ethylenic hydrocarbons having 2 to 10 carbons;

(ii) (meth) acrylates of formula: R ₂

H ₂ C = C COOR ₃

wherein R ₂ is a hydrogen atom or a methyl group (CH ₃ ); and R ₃ represents:

a linear or branched alkyl group comprising from 1 to 30 carbon atoms, in which one or more heteroatoms chosen from O, N, S and P are optionally intercalated; said alkyl group may further be optionally substituted by one or more substituents selected from OH, halogen atoms (Cl, Br, I and F), and -Si groups;

(R ' ₄ R' ₅ R ' ₆ ) and -Si (R' ₄ R 's) O, in which R' ₄ , R 's and R' 5, which may be identical or different, represent a hydrogen atom, an alkyl group, to C ₆ or a phenyl group;

- cycloalkyl, C ₃ to C _2; a C ₃ to C ₂₀ aryl group;

- a C ₄ -C ₃₀ aralkyl group (alkyl group -C _8);

a heterocyclic group comprising from 4 to 12 ring members containing one or more heteroatoms chosen from O, N and S, the ring being aromatic or not;

a heterocycloalkyl group (alkyl of 1 to 4 carbon atoms); wherein said cycloalkyl, aryl, aralkyl, heterocyclic or heterocycloalkyl groups possibly being optionally substituted by one or more substituents selected from hydroxyl groups, halogen atoms, and alkyl groups The C ₄ linear or branched in which is ( nt) optionally intercalated (s) one or more heteroatoms selected from 0, N, S and P, said alkyl groups may further be optionally substituted with one or more substituents selected from -OH, halogen atoms (Cl, Br, I and F), and the groups -Si (R ' ₄ R' ₅ R'e) and -Si (R ' ₄ R' ₅ ) O, wherein R ' ₄ , R' 5 and R '5, identical or different, represent a hydrogen atom, an alkyl group -C ₆ or phenyl; a group - (OC ₂ H ₄ ) _m -OR '', with m = 5 to 300 and R "= H or C 1 to C ₃₀ alkyl; a group - (OC ₃ H ₅ ) _m -OR '', with m = 5 to 300 and R "= H or C 1 to C ₃₀ alkyl; or a statistical mixture or block of groups (OC ₂ H ₄ ) _m and (OC ₃ H ₆ ) _m ; (iii) (meth) acrylamides of formula: wherein R ₈ is H or methyl; and R ₇ and R _{6, which are} identical or different, represent:

a hydrogen atom; or - a linear or branched alkyl group,

1 to 30 carbon atoms, in which is (are) optionally intercalated (s) one or more heteroatoms selected from 0, N, S and P; said alkyl group may further be optionally substituted by one or more substituents selected from -OH, halogen atoms (Cl, Br, I and F), and -Si groups;

(R ' ₄ R' ₅ R ' ₅ ) and -Si (R' ₄ R ' ₅ ) O, wherein R' ₄ , R ' ₅ and

R _'5 represent a hydrogen atom, an alkyl group with C ₅ or phenyl; a C ₃ -C ₁₂ cycloalkyl group;

- aryl, C ₃ -C ₂ o;

a C ₄ to C ₃₀ aralkyl group (C 1 to C ₈ alkyl group);

a heterocyclic group comprising from 4 to 12 ring members containing one or more heteroatoms chosen from O, N and S, the ring being aromatic or not;

a heterocycloalkyl (C ₁ -C ₄ alkyl) group; said cycloalkyl, aryl, aralkyl, heterocyclic or heterocycloalkyl groups may be optionally substituted with one or more substituents selected from hydroxyl groups, halogen atoms, and linear or branched C ₁ -C ₄ alkyl groups in which one or more heteroatoms selected from O, N, S and P are optionally intercalated, said alkyl groups being in addition, optionally substituted with one or more substituents selected from -OH, halogen atoms (Cl, Br, I and F), and -Si (R ' ₄ R' ₅ R'e) and -Si groups ( R ' ₄ R' ₅ ) O, wherein R '4, R' 5 and R ' ₅ , which may be identical or different, represent a hydrogen atom, a C ₁ -C ₅ alkyl group or a phenyl group;

a group - (OC ₂ H ₄ ) _m -OR '', with m = 5 to 300 and R "= H or C 1 to C ₃₀ alkyl; a group - (OC ₃ H ₅ ) _m -OR '', with m = 5 to 300 and R "= H or C 1 to C ₃₀ alkyl; or a statistical mixture or block of groups (OC ₂ H ₄ ) _m and (OC ₃ H ₅ ) _m ;

(iv) the vinyl compounds of formula:

CH ₂ = CH-R ₉ wherein R ₉ is a hydroxyl group; a halogen (Cl or F); an NH ₂ group; a group -OR ₀ wherein Rio represents a phenyl group or an alkyl group Ci-Ci ₂ (the monomer is a vinyl or allylic ether); an acetamide group (NHCOCH ₃ ); OCORn a group wherein Rn represents an alkyl group of 2 to 12 carbons, linear or branched (the monomer is a vinyl ester or allyl), cycloalkyl C ₃ -C ₂ aryl, C ₃ -C ₂₀ or in arallyle C ₄ -C ₃₀ ; or else R ₉ is chosen from:

a linear or branched alkyl group comprising 1 to 30 carbon atoms, in which one or more heteroatoms chosen from O, N, S and P are optionally intercalated; said group alkyl may further be optionally substituted with one or more substituents selected from -OH, halogen atoms (Cl, Br, I and F), and -Si groups

(R ' ₄ R' ₅ R ' ₆ ) and -Si (R' ₄ R ' ₅ ) O, in which R' ₄ , R '5 and R' 5, which may be identical or different, represent a hydrogen atom, a alkyl group -C ₆ or phenyl;

- cycloalkyl, C ₃ to C _2;

- aryl, C ₃ -C ₂ o; a C ₄ -C ₃₀ arylalkyl or alkylaryl group (C ₁ -C ₈ alkyl group);

a heterocyclic group of 4 to 12 members containing one or more heteroatoms chosen from O, N and S, the ring being aromatic or not; a heterocycloalkyl group (alkyl of 1 to 4 carbon atoms); said cycloalkyl, aryl, aralkyl, heterocyclic or heterocycloalkyl groups being optionally substituted by one or more substituents selected from hydroxyl groups, halogen atoms, and linear or branched alkyl groups of 1 to 4 carbon atoms in which optionally interspersed with one or more heteroatoms selected from O, N, S and P, said alkyl groups being furthermore optionally substituted with one or more substituents selected from -OH, the halogen atoms (Cl , Br, I and F) and the groups -Si (R ' ₄ R' ₅ R ' ₅ ) and -Si (R' ₄ R ' ₅ ) O, wherein R' ₄ , R '5 and R' 5, identical or different, represent a hydrogen atom, an alkyl group -C ₆ or phenyl; (v) the allylic compounds of formula:

CH ₂ = CH-CH ₂ -R ₉ or CH ₂ = C (CH ₃ ) -CH ₂ -R ₉ wherein R ₉ has the same meaning as above;

(vi) (meth) acrylic, (meth) acrylamide or vinylic silicone monomers.

14. Copolymer according to claim 12, in which the additional monomer is chosen from, alone or as a mixture: the (meth) acrylates and the

hydroxyalkyl (meth) acrylamides wherein the alkyl group comprises 2 to 4 carbon atoms;

- (meth) acrylates and (meth) acrylamides of alkoxy (Cl- ₄₎ alkyl (Cl- _4); (meth) acrylamide and N, N-dimethylacrylamide;

(meth) acrylates and (meth) acrylamides having - (OC ₂ H ₄ ) _m -OR 1 'group, with m = 5 to 300 and, R "= H or C ₁ to C ₄ alkyl; vinyllactams;

vinyl ethers;

vinylacetamide, N-vinylpyrrolidone, N-vinylcaprolactam;

polysaccharide (meth) acrylates such as sucrose acrylate and ethylglucoside (meth) acrylate.

The copolymer of claim 12, wherein the additional monomer is selected from, alone or in admixture:

T-butylbenzyl acrylate, t-butylcyclohexyl acrylate and isobornyl acrylate (94 ^° C.),

1 acrylate, furfuryl acrylate, n-hexyl (45 ⁰ C), 1 'acrylate, t-butyl ester (5O ⁰ C), the cyclohexyl acrylate (19 ⁰ C), the hydroxyethyl acrylate ( C ⁰ ), methyl acrylate (100 ^° C.), ethyl acrylate (-24 ^° C.), isobutyl acrylate (-24 ^° C.) and methoxyethyl acrylate (-33 ^° C. ⁰ C), n-butyl acrylate (-54 ^° C.), ethylhexyl acrylate (-50 ^° C.), hexyl acrylate, octyl acrylate and lauryl acrylate. Isooctyl acrylate, isodecyl acrylate; t-butylbenzyl methacrylate, t-butylcyclohexyl methacrylate, isobornyl methacrylate (111 ^° C.) and methyl methacrylate

(100 ^° C.), cyclohexyl methacrylate (83 ^° C.), ethyl methacrylate (65 ^° C.), benzyl methacrylate (54 ^° C.), isobutyl methacrylate (53 ^° C.) and methacrylate. butyl (20 ^° C.), n-hexyl methacrylate (-5 ^° C.), ethylhexyl methacrylate, octyl methacrylate, lauryl methacrylate, isooctyl methacrylate and isodecyl methacrylate; styrene (100 ^° C.), vinylcyclohexane, vinyl acetate (23 ^° C.), vinyl methyl ether (-34 ^° C.), vinyl neononanoate, and vinyl neododecanoate;

N-butylacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide, N, N-dibutylacrylamide, Nt-butylacrylamide, N-octylacrylamide.

16. Copolymer according to any one of the preceding claims, in which the block B comprises monomeric units derived from nonionic and / or hydrophobic hydrophilic monomers as defined above.

17. Copolymer according to any one of the preceding claims, which is a triblock copolymer of type A-B-C.

The copolymer of claim 17, wherein the B block is present in a content of from 5 to 95% by weight of the copolymer.

The copolymer of claim 17, wherein the B block is present at a content of greater than 50% by weight of the copolymer.

20. Copolymer according to any one of claims 17 to 19, wherein the sequence A and / or C comprises: monomer units derived from nonionic monomers chosen from:

the vinyl compounds of formula

CH ₂ = CH-R ₉ , R ₉ being as defined in the claim

13, * methacrylate compounds of formula: R ₂

H ₂ C = C COOR ₃ with R ₂ and R ₃ being as defined in claim 13; and

* mixtures thereof; and monomer units bearing at least one -CO ₂ H function derived from monomers chosen from acrylic acid and methacrylic acid.

21. Copolymer according to claim 20, wherein the monomer units derived from nonionic monomers are present in a content ranging from 1 to 99.5% relative to the total weight of the sequence.

22. Copolymer according to claim 20 or 21, wherein the monomeric units carrying at least one -CO ₂ H function are present in a content ranging from 0.5 to 99% relative to the total weight of the sequence.

23. Copolymer according to any one of claims 20 to 22, wherein the B sequence comprises monomer units derived from monomers chosen by (meth) acrylates of formula:

R ₂

H ₂ C = C COOR ₃ with R ₂ and R ₃ being as defined in claim 13.

24. Copolymer according to claim 23, wherein the (meth) acrylate monomers are chosen from n-hexyl methacrylate (Tg = -5 ° C), ethyl acrylate (Tg = -24 ° C), isobutyl acrylate (Tg = -24 ° C), n-butyl acrylate (Tg = -54 ° C), ethylhexyl acrylate (Tg = -50 ° C).

25. Copolymer according to any one of claims 17 to 24, wherein the triblock copolymer is selected from poly (styrene-co-methacrylic acid) -b-poly (n-butyl acrylate) -b- poly (styrene). co-methacrylic acid), poly (methyl methacrylate-co-methacrylic acid) -b- poly (n-butyl acrylate) -b-poly (methyl methacrylate-co-methacrylic acid).

26. Copolymer according to claim 25, in which the poly (styrene-co-methacrylic acid) -b-poly (n-butyl acrylate) -b-poly (styrene-co-methacrylic acid) copolymer is that for which:

the poly (n-butyl acrylate) block represents 71% by weight of the total copolymer;

the poly (styrene-co-methacrylic acid) sequences each comprise monomeric units derived from methacrylic acid in a proportion of 2% by weight of the total copolymer and monomeric units derived from styrene at a rate of 12.5% by weight of the total copolymer; a weight average molecular weight of

372,000 g. mol ^"1 .

27. Copolymer according to claim 25, in which the poly (methyl methacrylate-methacrylic acid) -b-poly (n-butyl acrylate) -b-poly (methyl methacrylate-co-methacrylic acid) copolymer is the for which :

the poly (n-butyl acrylate) block represents 35% by weight of the total copolymer;

the poly (methyl methacrylate-co-methacrylic acid) sequences each comprise monomeric units derived from methacrylic acid in a proportion of 3.25% by weight of the total copolymer and of monomeric units derived from methyl methacrylate at 29%; 25% by weight of the total copolymer; a weight average molecular weight of

150,000 g. mol ^"1 .

28. The copolymer according to claim 25, wherein the poly (methyl methacrylate-co-methacrylic acid) -b-poly (n-butyl acrylate) -b-poly (methyl methacrylate-co-methacrylic acid) copolymer is the for which :

the poly (n-butyl acrylate) block represents 65% by weight of the total copolymer; the poly (methyl methacrylate-co-methacrylic acid) sequences each comprise monomeric units derived from methacrylic acid in a proportion of 1.6% by weight of the total copolymer and of monomeric units derived from methyl methacrylate at a concentration of 9% by weight of the total copolymer; a weight average molecular weight of

29. Composition comprising at least 1% by weight, relative to the total weight of the composition, of a copolymer as defined according to any one of Claims 1 to 28.

30. The composition of claim 29, wherein the copolymer is neutralized, in whole or in part, with a mineral or organic base.

31. The composition of claim 30, wherein the mineral base is selected from alkali hydroxides, alkaline earth metal hydroxides, metal hydroxides, metalloid hydroxides.

32. The composition of claim 31, wherein the organic base is an amine.

33. Composition according to claim 31, in which the amine is an amine having a boiling point greater than 200 ^° C. under 1 atmosphere.

34. Composition according to any one of claims 30 to 33, wherein the degree of neutralization is greater than 0.1, preferably greater than 0.5.

35. A composition according to any one of 29 to 34, which is an adhesive composition.

36. The composition of claim 35, wherein the copolymer is present in a content of at least 5% by weight relative to the total weight of the composition.

37. The composition of claim 35 or 36, further comprising an additive selected from tackifying resins, plasticizers.

38. Composition according to claim 37, in which the plasticizer is chosen from trimellitate oils and oils that are predominantly naphthenic.

39. Composition according to claim 37, in which the tackifying resin is chosen from resins based on rosin (s), ester of rosin, polyterpene, hydroxylated polyester, terpene styrene, terpene pentaerythritol or terpene phenol. .

40. Tapes, labels and adhesive tapes comprising a composition as defined according to any one of Claims 35 to 39.

41. The composition of any one of claims 29 to 34, which is a thermoplastic composition.

42. The composition of claim 41, further comprising one or more thermoplastic polymers.

43. The composition of claim 42, wherein the thermoplastic polymer is selected from polymethyl methacrylate, polystyrene and polyvinyl chloride.

44. A process for preparing a composition as defined in claim 30, comprising a step of contacting the copolymer with a mineral or organic base in a liquid medium.

45. A process for the preparation of a composition as defined in claim 30, comprising a step of contacting, by melting, the copolymer with a mineral or organic base.

46. Use of a copolymer as defined in any one of claims 1 to 28 as a hot melt adhesive.