[001] The present invention relates to a liquid (meth) acrylic composition comprising a (meth) acrylic monomer, a (meth) acrylic polymer and a multistage polymer.

[002] In particular the present invention it relates to liquid composition comprising a (meth) acrylic monomer, a (meth) acrylic polymer and a multistage polymer that can be used as a syrup and especially as a syrup for impregnation.

[003] More particularly the present invention relates also to a process for preparing a liquid composition comprising a

(meth) acrylic monomer, a (meth) acrylic polymer and a multistage polymer .

[Technical problem]

[004] Impact modifiers are widely used to improve the impact strength for polymeric compositions with the aim to compensate their inherent brittleness or the embrittlement that occurs at ambient temperature but also and especially sub zero temperatures, notch sensitivity and crack propagation. So an impact modified polymer is a polymeric material whose impact resistance and toughness have been increased by the incorporation of phase micro domains of a rubbery material.

[005] This is usually done due to the introduction of microscopic rubber particles into the polymer matrix that can absorb the energy of an impact or dissipate it. One possibility is to introduce the rubber particles in form of core-shell particles. These core-shell particles that possess very generally a rubber core and a polymeric shell, having the advantage of a proper particle size of the rubber core for effective toughening and the grafted shell in order to have the adhesion and compatibility with the thermoplastic matrix.

[006] The performance of the impact modification is a function of the particles size, especially of the rubber part of the particle, and its quantity. There is an optimal average particle size m order to have the highest impact strength for a given quantity of added impact modifier particles.

[007] These primary impact modifier particles are usually added in form of powder particles to the polymeric material. These powder particles are agglomerated primary impact modifier particles. During the blending of the thermoplastic material with the powder particles the primary impact modifier particles are regained and are dispersed more or less homogenously dispersed in the thermoplastic material .

[008] While the particle size of the impact modifier particles in the range of nanometers, the range of the agglomerated powder particles is in the range of micrometers. Latter is much easier for handling.

[009] For many polymers, thermoplastic or thermoset polymers it is very difficult or nearly impossible to disperse correctly these multistage polymer in form of core shell particles as agglomerated dry powders. An ideal homogenous dispersion of the core-shell particle has no agglomerates after the dispersion in the thermoplastic material also called matrix.

[010] This is even more difficult if the multistage polymers should be homogenously distributed in a polymeric matrix which comprises also a fibrous substrate as for example fibre reinforced polymeric composites .

[011] The fibrous substrate is usually impregnated by a liquid composition, either a molten polymer or a liquid composition comprising monomers, oligomers and/or polymers.

[012] The objective of the present invention is to obtain liquid composition comprising a (meth) acrylic monomer, a (meth) acrylic polymer and a multistage polymer, with a homogenous dispersion of the multistage polymer.

[013] An objective of the present invention is also to have a liquid composition comprising a (meth) acrylic monomer, a

(meth) acrylic polymer and a multistage polymer, with a homogenous dispersion of the multistage polymer, that can be used in a polymerization process.

[014] Another objective of the present invention is to avoid or reduce significantly the agglomeration of multistage polymer.

[015] Still an additional objective is having a process for preparing a liquid composition comprising a (meth) acrylic monomer, a (meth) acrylic polymer and a multistage polymer, with a homogenous dispersion of the multistage polymer.

[016] Still a further objective is the use of the composition comprising comprising a monomer, a (meth) acrylic polymer for the impact modification of polymers.

[017] Still a further objective is to obtain liquid composition comprising a (meth) acrylic monomer, a (meth) acrylic polymer and a multistage polymer, with a homogenous dispersion of the multistage polymer as impregnation liquid for a fibrous substrate or the use the liquid composition in an impregnation process for impregnating a fibrous substrate.

[018] Still another objective of the present invention is to wet completely, correctly and in a homogenous way a fibrous substrate during impregnation with a liquid composition comprising a multistage polymer.

[BACKGROUND OF THE INVENTION ]Pr±or art

[019] The document WO2014/013028 discloses an impregnation process for a fibrous substrate, a liquid (meth) acrylic syrup for the impregnation process, its method of polymerization and structured article obtained thereof. The syrup comprises a (meth) acrylic monomer, a (meth) acrylic polymer and optionally impact modifier in the form of fine particles.

[020] The document WO2014/135815 discloses a viscous liquid (meth) acrylic syrup mainly containing methacrylic or acrylic components and an impact-modifying additive for reinforcing the impact strength of a thermoplastic material obtained after polymerization of the syrup. The impact-modifying additive is based on elastomeric domains consisting of macromolecular blocks of flexible nature. A multi stage polymer especially in form of core/shell particles is not disclosed.

[021] The document WO2014/135816 discloses a viscous liquid (meth) acrylic syrup mainly containing methacrylic or acrylic components and organic or mineral fillers intended to reduce the proportion of residual monomer after polymerization of the (meth) acrylic syrup. The organic filler is chosen from crosslinked PMMA beads. A multi stage polymer especially in form of core/shell particles is not disclosed.

[022] None of the prior art documents discloses a composition as claimed or a process for obtaining it or its use.

[Brief description of the invention]

[023] Surprisingly it has been found that a liquid composition comprising

a) a (meth) acrylic polymer (PI),

b) a multi stage polymer and

c) a (meth) acrylic monomer (Ml)

wherein the multistage polymer to monomer (Ml) ratio by weight in the liquid composition is between 1/99 and 25/75, is less viscous than a composition not comprising the (meth) acrylic polymer (PI) .

[024] Surprisingly it has also been found that a liquid composition comprising

a) a (meth) acrylic polymer (PI),

b) a multi stage polymer and

c) a (meth) acrylic monomer (Ml)

wherein the multistage polymer to monomer (Ml) ratio by weight in the liquid composition is between 1/99 and 25/75, possesses a better dispersion of the multistage polymer than a composition not comprising the (meth) acrylic polymer (PI) .

[025] Surprisingly it has also been found that a liquid composition comprising

a) a (meth) acrylic polymer (PI),

b) a multi stage polymer and

c) a (meth) acrylic monomer (Ml)

wherein the multistage polymer to monomer (Ml) ratio by weight in the liquid composition is between 1/99 and 25/75, can be used to prepare a better dispersion of the multistage polymer in the monomer (Ml) than a composition not comprising the (meth) acrylic polymer (PI) .

[026] Surprisingly it has also been found that a process for manufacturing a liquid composition comprising the steps of

a) preparing a composition comprising a the (meth) acrylic polymer (PI) and a multi stage polymer

b) mixing the composition of previous step with a (meth) acrylic monomer (Ml)

wherein the multistage polymer to monomer (Ml) ratio by weight in the liquid composition is between 1/99 and 25/75, yields to a liquid composition that is less viscous than a composition not comprising the (meth) acrylic polymer (PI) .

[027] Surprisingly it has also been found that a process for manufacturing a liquid composition comprising the steps of

a) preparing a composition comprising a the (meth) acrylic polymer (PI) and a multi stage polymer

b) mixing the composition of previous step with a (meth) acrylic monomer (Ml)

wherein the multistage polymer to monomer (Ml) ratio by weight in the liquid composition is between 1/99 and 25/75, yields to a impregnation liquid in form of a (meth) acrylic syrup.

[028] Surprisingly it has also been found that a liquid composition comprising

a) a (meth) acrylic polymer (PI),

b) a multi stage polymer and

c) a (meth) acrylic monomer (Ml)

wherein the multistage polymer to monomer ratio by weight in the liquid composition is between 1/99 and 25/75, can be used for impregnating a fibrous substrate.

[029] Surprisingly it has also been found that a liquid composition comprising

a) a (meth) acrylic polymer (PI),

b) a multi stage polymer and

c) a (meth) acrylic monomer (Ml)

wherein the multistage polymer to monomer ratio by weight in the liquid composition is between 1/99 and 25/75, can be used in impregnation process for impregnating a fibrous substrate, wherein said fibrous substrate is made of long fibres.

[Detailed description of the invention]

[030] According to a first aspect, the present invention relates to a liquid composition comprising

a) a (meth) acrylic polymer (PI),

b) a multi stage polymer and

c) a (meth) acrylic monomer (Ml)

wherein the multistage polymer to monomer ratio by weight in the liquid composition is between 1/99 and 25/75.

[031] According to a second aspect, the present invention relates to a process for manufacturing a liquid composition comprising the steps of

a) preparing a composition comprising a the (meth) acrylic polymer (PI) and a multi stage polymer

b) mixing the composition of previous step with a (meth) acrylic monomer (Ml)

wherein the multistage polymer to monomer ratio by weight in the liquid composition is between 1/99 and 25/75.

[032] In a third aspect the present invention relates to the use a liquid composition comprising

a) a (meth) acrylic polymer (PI),

b) a multi stage polymer and

c) a (meth) acrylic monomer (Ml)

wherein the multistage polymer to monomer ratio by weight in the liquid composition is between 1/99 and 25/75, for impregnating a fibrous substrate.

[033] In a forth aspect the present invention relates to the use a liquid composition comprising

a) a (meth) acrylic polymer (PI),

b) a multi stage polymer and

c) a (meth) acrylic monomer (Ml)

wherein the multistage polymer to monomer ratio by weight in the liquid composition is between 1/99 and 25/75, in an impregnation process for impregnating a fibrous substrate, wherein said fibrous substrate is made of long fibres.

[034] By the term "polymer powder" as used is denoted a polymer comprising powder grain in the range of at least 1 micrometer (μιτι) obtained by agglomeration of primary polymer comprising particles in the nanometer range.

[035] By the term "primary particle" as used is denoted a spherical polymer comprising particle in the nanometer range. Preferably the primary particle has a weight average particle size between 20nm and 800nm.

[036] By the term "particle size" as used is denoted the volume average diameter of a particle considered as spherical.

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

[038] By "multistage polymer" as used is denoted a polymer formed in sequential fashion by a multi-stage polymerization process. One preferred process is a multi-stage emulsion polymerization process in which the first polymer is a first-stage polymer and the second polymer is a second-stage polymer, i.e., the second polymer is formed by emulsion polymerization in the presence of the first emulsion polymer.

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

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

[041] By the term "epoxy resin" as used is understood any organic compound having at least two functional groups of oxirane type which can be polymerized by ring opening.

[042] By the term " (meth) acrylic resin" as used is understood adhesives based on acrylic and methacrylic monomers.

[043] By the term "masterbatch" as used is understood composition that comprises an additive in high concentration in a carrier material. The additive is dispersed in the carrier material.

[044] By the term "impact modifier" as used is understood a material that once incorporated in a polymeric material increases the impact resistance and toughness of that polymeric material by phase micro domains of a rubbery material or rubber polymer.

[045] By the term "rubber" as used is denoted to the thermodynamic state of the polymer above its glass transition.

[046] By the term "rubber polymer" as used is denoted a polymer that has a glass transition temperature (Tg) below 0°C.

[047] The liquid composition of the invention comprises at least three components a) a (meth) acrylic polymer (PI), b) a multi stage polymer, c) a (meth) acrylic monomer (Ml), wherein the multistage polymer to monomer ratio by weight in the liquid composition is between 1/99 and 25/75, in the liquid composition comprising the three compounds .

[048] Preferably the multistage polymer to monomer (Ml) ratio by weight in the liquid composition is between 2/98 and 24/76, more preferably between 3/97 and 23/77, still more preferably between 4/96 and 22/78 and advantageously between 5/95 and 20/80.

[049] The dynamic viscosity of the liquid composition according to the invention is in a range from 10 mPa*s to 1 000 000 mPa*s, preferably from 10 mPa*s to 500 000 mPa*s and advantageously from

50 mPa*s to 300 000 mPa*s. The viscosity of the liquid composition (sometimes also called syrup) can be easily measured with a

Rheometer with a shear rate between O.ls-1 and lOOs-1. The dynamic viscosity is measured at 25°C. If there is a shear thinning the viscosity is measured at a shear rate of ls-1.

[050] With regard to the (meth) acrylic polymer (Pi), it has a mass average molecular weight Mw of less than 100 OOOg/mol, preferably less than 90 OOOg/mol, more preferably less than 80 OOOg/mol, still more preferably less than 70 OOOg/mol, advantageously less than 60 000 g/mol, more advantageously less than 50 000 g/mol and still more advantageously less than 40 000 g/mol.

[051] The (meth) acrylic polymer (PI), it has a mass average molecular weight Mw above 2 OOOg/mol, preferably above 3000g/mol, more preferably above 4000g/mol, still more preferably above 5 OOOg/mol, advantageously above 6 000 g/mol, more advantageously above 6 500 g/mol and still more advantageously above 7 000 g/mol and most advantageously above 10 000 g/mol.

[052] The mass average molecular weight Mw of (meth) acrylic polymer (PI) is between 2 OOOg/mol and 100 OOOg/mol, preferable between

3 000 g/mol and 90 000 g/mol and more preferably between

4 OOOg/mol and 80 OOOg/mol advantageously between 5000g/mol and 70 OOOg/mol, more advantageously between 6 OOOg/mol and 50 OOOg/mol and most advantageously between 10 OOOg/mol and 40 OOOg/mol .

[053] Preferably the (meth) acrylic polymer (PI) is a copolymer comprising (meth) acrylic monomers. More preferably the (meth) acrylic polymer (PI) is a (meth) acrylic polymer. Still more preferably the (meth) acrylic polymer (PI) comprises at least 50wt% monomers chosen from CI to C12 alkyl (meth) acrylates . Advantageously preferably the (meth) acrylic polymer (PI) comprises at least 50 wt% of monomers chosen from CI to C4 alkyl methacrylate and CI to C8 alkyl acrylate monomers and mixtures thereof .

[054] Preferably the glass transition temperature Tg of the (meth) acrylic polymer (PI) is between 30°C and 150°C. The glass transition temperature of the (meth) acrylic polymer (PI) is more preferably between 40°C and 150°C, advantageously between 45°C and 150°C and more advantageously between 50°C and 150°C.

[055] Preferably the polymer (meth) acrylic polymer (PI) is not crosslinked .

[056] Preferably the polymer (meth) acrylic polymer (PI) is not grafted on any other polymer or polymers.

[057] In a first preferred embodiment the (meth) acrylic polymer (PI) comprises from 50wt% to 100wt% methyl methacrylate, preferably from 80wt% to 100wt% methyl methacrylate, still more preferably from 80wt% to 99.8wt% methyl methacrylate and from 0.2wt% to 20wt% of an CI to C8 alkyl acrylate monomer. Advantageously the CI to C8 alkyl acrylate monomer is chosen from methyl acrylate, ethyl acrylate or butyl acrylate.

[058] In a second preferred embodiment the (meth) acrylic polymer (PI) comprises between 0wt% and 50wt% of a functional monomer. Preferably the (meth) acrylic polymer (PI) comprises between 0wt% and 30wt% of the functional monomer, more preferably between lwt% and 30wt%, still more preferably between 2wt% and 30wt%, advantageously between 3wt% and 30wt%, more advantageously between 5wt% and 30wt% and most advantageously between 5wt% and 30wt%.

[059] Preferably the functional monomer of the second preferred embodiment is a (meth) acrylic monomer. The functional monomer has the formula (1) or (2) :

[060] wherein in both formulas (1) and (2) Ri is chosen from H or CH3; and in formula (1) Y is 0, R5 is H or an aliphatic or aromatic radical having at least one atom that is not C or H; and in formula (2) Y is N and R4 and/or R3 is H or an aliphatic or aromatic radical.

[061] Preferably the functional monomer (1) or (2) is chosen from glycidyl (meth) acrylate, acrylic or methacrylic acid, the amides derived from these acids, such as, for example, dimethylacrylamide, 2-methoxyethyl acrylate or methacrylate, 2-aminoethyl acrylates or methacrylates are optionally quaternized, acrylate or methacrylate monomers comprising a phosphonate or phosphate group, alkyl imidazolidinone (meth) acrylates, polyethylene glycol (meth) acrylates. Preferably the polyethylene glycol group of polyethylene glycol (meth) acrylates has a molecular weight ranging from 400g/mol to 10 000 g/mol

[062] The multistage polymer according to the invention has at least two stages that are different in its polymer composition.

[063] The multistage polymer is preferably in form of polymer particles considered as spherical particles. These particles are also called core shell particles. The first stage forms the core, the second or all following stages the respective shells. Such a multistage polymer which is also called core/shell particle is preferred.

[064] With regard to the polymeric particle according to the invention, which is the primary particle, it has a weight average particle size (diameter) between 15nm and 900nm. Preferably the weight average particle size of the polymer is between 20nm and 800nm, more preferably between, more preferably between 25nm and 600nm, still more preferably between 30nm and 550nm, again still more preferably between 35nm and 500nm, advantageously between 40nm and 400nm, even more advantageously between 75nm and 350nm and advantageously between 80nm and 300nm. The primary polymer particles can be agglomerated giving a polymer powder comprising either the multi stage polymer or the (meth) acrylic polymer (PI) and the multi stage polymer.

[065] The polymer particle is obtained by a multistage process such as a process comprising two, three or more stages.

[066] The polymer particle has a multilayer structure comprising at least one layer (A) comprising a polymer (Al) having a glass transition temperature below 0°C and another layer (B) comprising a polymer (Bl) having a glass transition temperature over 30°C.

[067] In a first preferred embodiment the polymer (Bl) having a glass transition temperature of at least 30°C is the external layer of the polymer particle having the multilayer structure.

[068] In a second preferred embodiment the polymer (Bl) having a glass transition temperature of at least 30°C is an intermediate layer of the polymer particle having the multilayer structure, before the multistage polymer is brought into contact with the monomer (Ml) .

[069] Preferably the stage (A) is the first stage and the stage (B) comprising polymer (Bl) is grafted on stage (A) comprising polymer (Al) or another intermediate layer. By first stage is meant that the stage (A) comprising polymer (Al) is made before the stage (B) comprising polymer (Bl) .

[070] The polymer (Al) having a glass transition temperature below 0°C in the layer (A) is never made during the last stage of the multistage process. This means that the polymer (Al) is never in the external layer of the particle with the multilayer structure. The polymer (Al) having a glass transition temperature below 0°C in the layer (A) is either in the core of the polymer particle or one of the inner layers.

[071] Preferably the polymer (Al) having a glass transition temperature below 0°C in the layer (A) is made in the first stage of the multistage process forming the core for the polymer particle having the multilayer structure and/or before the polymer (Bl) having a glass transition temperature over 60°C. Preferably the polymer (Al) is having a glass transition temperature below -5°C, more preferably below -15°C, advantageously below -25°C.

[072] In a first preferred embodiment the polymer (Bl) having a glass transition temperature over 60 °C is made in the last stage of the multistage process forming the external layer of the polymer particle having the multilayer structure.

[073] In a second preferred embodiment the polymer (Bl) having a glass transition temperature of at least 30°C is an intermediate layer of the polymer particle having the multilayer structure, is made in a stage after the stage for forming the polymer (Al) of the multistage process.

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

[075] The glass transition temperature Tg of the respective polymers can be estimated for example by dynamic methods as thermo mechanical analysis.

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

[077] With regard to the polymer (Al) , in a first embodiment it is a (meth) acrylic polymer comprising at least 50wt% of monomers from alkyl acrylates .

[078] More preferably the polymer (Al) comprises a comonomer or comonomers which are copolymerizable with alkyl acrylate, as long as polymer (Al) is having a glass transition temperature of less than 0°C.

[079] The comonomer or comonomers in polymer (Al) are preferably chosen from (meth) acrylic monomers and/or vinyl monomers.

[080] The (meth) acrylic comonomer in polymer (Al) comprises monomers chosen from CI to C12 alkyl (meth) acrylates . Still more preferably (meth) acrylic comonomer in polymer (Al) comprises monomers of CI to C4 alkyl methacrylate and/or CI to C8 alkyl acrylate monomers.

[081] Most preferably the acrylic or methacrylic comonomers of the polymer (Al) are chosen from methyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, tert-butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and mixtures thereof, as long as polymer (Al) is having a glass transition temperature of less than 0°C.

[082] Preferably the polymer (Al) is crosslinked. This means that a crosslinker is added to the other monomer or monomers. A crosslinker comprises at least two groups that can be polymerized.

[083] In one specific embodiment polymer (Al) is a homopolymer of butyl acrylate.

[084] In another specific embodiment polymer (Al) is a copolymer of butyl acrylate and at least one crosslinker. The crosslinker presents less than 5wt% of this copolymer.

[085] More preferably the glass transition temperature Tg of the polymer (Al) of the first embodiment is between -100°C and 0°C, even more preferably between -100°C and -5°C, advantageously between -90°C and -15°C and more advantageously between -90°C and -25°C.

[086] With regard to the polymer (Al) , in a second embodiment the polymer (Al) is a silicone rubber based polymer. The silicone rubber for example is polydimethyl siloxane. More preferably the glass transition temperature Tg of the polymer (Al) of the second embodiment is between -150°C and 0°C, even more preferably between -145°C and -5°C, advantageously between -140°C and -15°C and more advantageously between -135°C and -25°C.

[087] With regard to the polymer (Al) , in a third embodiment the polymer (Al) having a glass transition temperature below 0°C comprises at least 50wt% of polymeric units coming from isoprene or butadiene and the stage (A) is the most inner layer of the polymer particle having the multilayer structure. In other words the stage (A) comprising the polymer (Al) is the core of the polymer particle.

[088] By way of example, the polymer (Al) of the core of the second embodiment, mention may be made of isoprene homopolymers or butadiene homopolymers, isoprene-butadiene copolymers, copolymers of isoprene with at most 98wt% of a vinyl monomer and copolymers of butadiene with at most 98wt% of a vinyl monomer. The vinyl monomer may be styrene, an alkylstyrene, acrylonitrile, an alkyl (meth) acrylate, or butadiene or isoprene. In one embodiment the core is a butadiene homopolymer.

[089] More preferably the glass transition temperature Tg of the polymer (Al) of the third embodiment comprising at least 50wt% of polymeric units coming from isoprene or butadiene is between -100°C and 0°C, even more preferably between -100°C and -5°C, advantageously between -90 °C and -15 °C and even more advantageously between -90°C and -25°C.

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

[091] Preferably the polymer (Bl) comprises at least 70wt% monomers chosen from CI to C12 alkyl (meth) acrylates . Still more preferably the polymer (Bl) comprises at least 80wt% of monomers CI to C4 alkyl methacrylate and/or CI to C8 alkyl acrylate monomers.

[092] The polymer (Bl) can be crosslinked.

[093] Most preferably the acrylic or methacrylic monomers of the polymer (Bl) are chosen from methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and mixtures thereof, as long as polymer (Bl) is having a glass transition temperature of at least 30°C.

[094] Advantageously the polymer (Bl) comprises at least 50wt%, more advantageously at least 60wt% and even more advantageously at least 70wt% of monomer units coming from methyl methacrylate.

[095] Preferably the glass transition temperature Tg of the polymer (Bl) is between 30°C and 150°C. The glass transition temperature of the polymer (Bl) is more preferably between 50°C and 150°C, still more preferably between 70°C and 150°C, advantageously between 90°C and 150°C and more advantageously between 90°C and 130°C.

[096] In another embodiment the multi stage polymer as described previously, has an additional stage, which is the (meth) acrylic polymer (PI) . The primary polymer particle according to this embodiment of the invention has a multilayer structure comprising at least one stage (A) comprising a polymer (Al) having a glass transition temperature below 0°C, at least one stage (B) comprising a polymer (Bl) having a glass transition temperature over 30°C and at least one stage (P) comprising the (meth) acrylic polymer (PI) having a glass transition temperature between 30°C and 150°C.

[097] Preferably the (meth) acrylic polymer (PI) is not grafted on any of the polymers (Al) or (Bl) .

[098] With regard to the process for manufacturing the multistage polymer according to the invention it comprises the steps of

a) polymerizing by emulsion polymerization of a monomer or monomer mixture (Am) to obtain at least one layer (A) comprising polymer (Al) having a glass transition temperature of less than 0°C

b) polymerizing by emulsion polymerization of a monomer or monomer mixture (Bm) to obtain layer (B) comprising a polymer (Bl) having a glass transition temperature of at least 30°C

the monomer or monomer mixture (Am) and the monomer or monomer mixture (Bm) are chosen from monomers according to the composition for polymer (Al) and polymer (Bl) given earlier.

[099] Preferably the step a) is made before step b) . More preferably step b) is performed in presence of the polymer (Al) obtained in step a), if there are only two stages.

[0100] Advantageously the process for for manufacturing the multistage polymer composition according to the invention is a multistep process comprises the steps one after the other of

a) polymerizing by emulsion polymerization of a monomer or monomer mixture (Am) to obtain one layer (A) comprising polymer (Al) having a glass transition temperature of less than 0°C

b) polymerizing by emulsion polymerization of a monomer or monomer mixture (Bm) to obtain layer (B) comprising a polymer (Bl) having a glass transition temperature of at least 30°C.

[0101] The respective monomers or monomer mixtures (Am) and (Bm) for forming the layers (A) and (B) respectively comprising the polymers (Al) and (Bl) respectively and the characteristics of the respective polymers (Al) and (Bl) are the same as defined before .

[0102] The process for manufacturing the multistage polymer can comprise additional steps for additional stages between the steps a) and b) .

[0103] The process for manufacturing the multistage polymer can also comprise additional steps for additional stages before the steps a) and b) . A seed could be used for polymerizing by emulsion polymerization the monomer or monomers mixture (Am) to obtain the layer (A) comprising polymer (Al) having a glass transition temperature of less than 0°C. The seed is preferably a thermoplastic polymer having a glass transition temperature of at least 20°C.

[0104] The multistage polymer is obtained as an aqueous dispersion of the polymer particles. The solid content of the dispersion is between 10wt% and 65wt%.

[0105] With regard to the process for manufacturing the (meth) acrylic polymer (Pi) according to the invention is comprises the step of polymerizing the respective (meth) acrylic monomers (Plm) . The respective (meth) acrylic monomers (Plm) are the same as defined before for the the (meth) acrylic polymer (PI) and two preferred embodiments the (meth) acrylic polymer (PI) .

[0106] The (meth) acrylic homo or copolymer (PI) could be made in batch or semi-continuous process:

for the batch process, the mixture of monomers is introduced in one shot just before or after introduction of one or part of the initiator system

for the semi-continuous process, the monomer mixture is added in multiple shots or continuously in parallel to the initiator addition (the initiator is also added in multiple shots or continuously) during a defined period of addition which could be in the range 30 to 500min.

[0107] The process for preparing the polymer composition comprising the (meth) acrylic polymer (PI) and the multi stage polymer has two preferred embodiments.

[0108] In a first preferred embodiment of the process, the (meth) acrylic polymer (PI) is polymerized in the presence of the multistage polymer. The (meth) acrylic polymer (PI) is made as an additional stage of the multistage polymer.

[0109] In a second preferred embodiment of the process, the (meth) acrylic polymer (PI) is polymerized apart and mixed or blended with the multistage polymer.

[0110] With regard to the process according to the first preferred embodiment for preparing the polymer composition comprising the (meth) acrylic polymer (PI) and the multi stage polymer, it comprises the steps of

a) polymerizing by emulsion polymerization of a monomer or monomer mixture (Am) to obtain one layer in stage (A) comprising polymer (Al) having a glass transition temperature of less than 0°C

b) polymerizing by emulsion polymerization of a monomer or monomer mixture (Bm) to obtain layer in stage (B) comprising a polymer (Bl) having a glass transition temperature of at least 30°C

c) polymerizing by emulsion polymerization of a monomer or monomer mixture (Plm) to obtain a layer in this additional stage comprising the (meth) acrylic polymer (PI) having a glass transition temperature of at least 30°C

characterized that the (meth) acrylic polymer (PI) has a mass average molecular weight Mw of less than 100 OOOg/mol.

[0111] Preferably the step a) is made before step b) .

[0112] More preferably step b) is performed in presence of the polymer (Al) obtained in step a) .

[0113] Advantageously the method for for manufacturing the polymer composition comprising the (meth) acrylic polymer (PI) and the multi stage polymer is a multistep process and comprises the steps one after the other of

a) polymerizing by emulsion polymerization of a monomer or monomer mixture (Am) to obtain one layer in stage (A) comprising polymer (Al) having a glass transition temperature of less than 0°C

b) polymerizing by emulsion polymerization of a monomer or monomer mixture (Bm) to obtain layer in stage (B) comprising a polymer (Bl) having a glass transition temperature of at least 30°C

c) polymerizing by emulsion polymerization of a monomer or monomer mixture (Plm) to obtain a layer in this additional stage comprising the (meth) acrylic polymer (PI) having a glass transition temperature of at least 30°C

characterized that the (meth) acrylic polymer (PI) has a mass average molecular weight Mw of less than 100 OOOg/mol.

[0114] The respective monomers or monomer mixtures (Am) , (Bm) and (Plm) for forming the layers (A) , (B) and additional stage respectively comprising the polymers (Al), (Bl) and (PI) respectively, are the same as defined before. The characteristics of the polymers (Al), (Bl) and (PI) respectively, are the same as defined before.

[0115] Preferably the method for manufacturing the polymer composition comprising the (meth) acrylic polymer (PI) and the multi stage polymer comprises the additional step d) of recovering of this polymer composition.

[0116] By recovering is meant partial or separation between the aqueous and solid phase, latter comprises the polymer composition.

[0117] More preferably according to the invention the recovering of the polymer composition is made by coagulation or by spray-drying.

[0118] Spray drying is the preferred method for the recovering and/or drying for the manufacturing method for a polymer powder composition if the polymer (Al) having a glass transition temperature below 0°C comprises at least 50wt% of polymeric units coming from alkyl acrylate and the stage (A) is the most inner layer of the polymer particle having the multilayer structure.

[0119] Coagulation is the preferred method for the recovering and/or drying for the manufacturing method for a polymer powder composition according to the present invention if the polymer (Al) having a glass transition temperature below 10 °C comprises at least 50wt% of polymeric units coming from isoprene or butadiene and the stage (A) is the most inner layer of the polymer particle having the multilayer structure.

[0120] The method for manufacturing the polymer composition according to the invention can comprise optionally the additional step e) of drying of the polymer composition.

[0121] Preferably the drying step e) is made if the step d) of recovering of the polymer composition is made by coagulation. [0122] Preferably after the drying step an e) the polymer composition comprises less than 3 t%, more preferably less than 1.5wt% advantageously less than 1% of humidity or water.

[0123] The humidity of a polymer composition can be measure with a thermo balance.

[0124] The drying of the polymer can be made in an oven or vacuum oven with heating of the composition for 48hours at 50°C.

[0125] With regard to the process according to the second preferred embodiment for preparing the polymer composition comprising the (meth) acrylic polymer (PI) and the multi stage polymer, it comprises the steps of

a) mixing of the (meth) acrylic polymer (PI) and the multi stage polymer

b) recovering the obtained mixture of previous step in form of a polymer powder

wherein the (meth) acrylic polymer (PI) and the multi stage polymer in step a) are in form of a dispersion in aqueous phase.

[0126] The quantities of the aqueous dispersion of the (meth) acrylic polymer (PI) and the aqueous dispersion of the multi stage polymer are chosen in a way that the weight ratio of the multi stage polymer based on solid part only in the obtained mixture is at least 5wt%, preferably at least 10wt%, more preferably at least 20wt% and advantageously at least 50wt%.

Claims

A liquid composition comprising

a) a (meth) acrylic polymer (PI),

b) a multistage polymer and

c) a (meth) acrylic monomer (Ml)

wherein the multistage polymer to monomer ratio by weight in the liquid composition is between 1/99 and 25/75.

The composition according to claim 1, characterized that the (meth) acrylic polymer (PI) has a mass average molecular weight Mw of less than 100 OOOg/mol.

The composition according to claim 1, characterized that the (meth) acrylic polymer (PI) has a mass average molecular weight Mw of less than 50 000 g/mol.

The composition according to characterized that the (meth) acrylic polymer (PI) mass average molecular weight Mw above 5 OOOg/mol.

The composition according to claim 1, characterized that the (meth) acrylic polymer (PI) has a mass average molecular weight Mw between 5 OOOg/mol and 70 OOOg/mol, more advantageously between 6 OOOg/mol and 50 OOOg/mol.

the multistage polymer to monomer ratio by weight in the liquid composition is between 2/98 and 24/76, more preferably between 3/97 and 23/77, still more preferably between 4/96 and 22/78 and advantageously between 5/95 and 20/80.

The composition according to claim 1 or 2, characterized that the (meth) acrylic polymer (PI) is soluble in the (meth) acrylic monomer (Ml) .

The composition according to any of claims 1 to 7, characterized that the monomer (Ml) is chosen from acrylic acid, methacrylic acid, alkyl acrylic monomers, alkyl methacrylic monomers and mixtures thereof, the alkyl group having from 1 to 22 carbons, either linear, branched or cyclic; preferably the alkyl group having from 1 to 12 carbons, either linear, branched or cyclic.

9. The composition according to any of claims 1 to 7, characterized that the monomer (Ml) is chosen is chosen from methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, methacrylic acid, acrylic acid, n-butyl acrylate, iso-butyl acrylate, n- butyl methacrylate, iso-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate and mixtures thereof .

10. The composition according to any of claims 1 to 9, characterized that the multi stage polymer comprises

a) one stage (A) comprising a polymer (Al) having a glass transition temperature of less than 0°C

b) , one stage (B) comprising a polymer (Bl) having a glass transition temperature of at least 30°C.

11. The composition according to claim 10, characterized that the stage (A) is the first stage and that stage (B) comprising polymer (Bl) is grafted on stage (A) comprising polymer (Al) .

12. The composition according to any of claims 10 to 11 characterized that the polymers (Al) and (Bl) are acrylic or methacrylic polymers.

13. The composition according to any of claims 10 to 11 characterized that the polymer (Al) comprises at least 50 t% of polymeric units coming from isoprene or butadiene.

14. The composition according to any of claims 1 to 13 characterized that the (meth) acrylic polymer (PI) comprises at least 50 t% monomers chosen from CI to C12 alkyl (meth) acrylates .

15. The composition according to any of claims 1 to 13 characterized that the (meth) acrylic polymer (PI) comprises from 50wt% to 100wt% methyl methacrylate, preferably from 80wt% to 100wt% methyl methacrylate, still more preferably from 80wt% to 99.8 t% methyl methacrylate and from 0.2 t% to 20wt% of an CI to C8 alkyl acrylate monomer.

16. The composition according to any of claims 1 to 13 characterized that the (meth) acrylic polymer (PI) comprises between 0wt% and 50wt% of a functional monomer.

17. The composition according to any of claims 1 to 13 characterized that the (meth) acrylic polymer (PI) comprises between lwt% and 30wt% of a functional monomer.

18. The composition according to claim 12 or 13, characterized that the functional comonomer is chosen from glycidyl (meth) acrylate, acrylic or methacrylic acid, the amides derived from these acids, such as, for example, dimethylacrylamide, 2-methoxyethyl acrylate or methacrylate, 2-aminoethyl acrylates or methacrylates are optionally quaternized, acrylate or methacrylate monomers comprising a phosphonate or phosphate group, alkyl imidazolidinone (meth) acrylates, polyethylene glycol (meth) acrylates. Preferably the polyethylene glycol group of polyethylene glycol (meth) acrylates has a molecular weight ranging from 400g/mol to 10 000 g/mol.

19. A process for manufacturing a liquid composition according to any of claims 1 to 18 comprising the steps of

a) preparing a composition comprising a (meth) acrylic polymer (PI) and a multi stage polymer

b) mixing the composition of previous step with a (meth) acrylic monomer (Ml)

wherein the multistage polymer to monomer ratio in the liquid composition is between 1/99 and 25/75.

20. The process according to claim 19, characterized that the (meth) acrylic polymer (PI) has a mass average molecular weight Mw of less than 100 OOOg/mol.

The process according to claim 19, characterized that the (meth) acrylic polymer (PI) has a mass average molecular weight Mw of has a mass average molecular weight Mw between 5 OOOg/mol and 70 OOOg/mol.

22. The process according to claim 19, characterized that the (meth) acrylic polymer (PI) has a mass average molecular weight Mw between 6 OOOg/mol and 50 OOOg/mol.

23. An impregnation process for impregnating a fibrous substrate, wherein said fibrous substrate comprises long fibres and said process comprises a step of impregnating said fibrous substrate with a liquid composition comprising:

a) a (meth) acrylic polymer (PI),

b) a multistage polymer and

c) a (meth) acrylic monomer (Ml)

wherein the multistage polymer to monomer ratio by weight in the liquid composition is between 1/99 and 25/75.

24. The impregnation process according to claim 23, characterized that the (meth) acrylic polymer (PI) has a mass average molecular weight Mw of less than 100 OOOg/mol.

25. The impregnation process according to claim 23, characterized that the (meth) acrylic polymer (PI) has a mass average molecular weight Mw between 5 OOOg/mol and 70 OOOg/mol.

26. The impregnation process according to claim 23, characterized that the (meth) acrylic polymer (PI) has a mass average molecular weight Mw between 6 OOOg/mol and 50 OOOg/mol.

27. Use of the of the liquid composition according to any of claims 1 to 18 or obtained by the process according to any of claims 19 to 26 to prepare a better dispersion of the multistage polymer in the monomer (Ml) .

28. Use of the of the liquid composition according to any of claims 1 to 18 or obtained by the process according to any of claims 19 to 26 for the preparation of impact modified polymers .

29. Use of the of the liquid composition according to any of claims 1 to 18 or obtained by the process according to any of claims 19 to 26 as an impregnation liquid (meth) acrylic syrup, preferably for a fibrous substrate.

30. Use of the of the liquid composition according to any of claims 1 to 18 or obtained by the process according to any of claims 19 to 26 in an impregnation process for impregnating a fibrous substrate.