[Field of invention]

[001] The invention relates to a method of impregnating a fibrous substrate, a liquid composition of polymer-based resin for the implementation of said process of impregnation, and the impregnated substrate obtained by implementing said method impregnation.

[002] More particularly, the invention relates to an industrial process for impregnating a fibrous substrate with a viscous liquid mixture based on methacrylic or acrylic components. Such a method including obtaining three-dimensional parts, e.g., parts or assemblies of mechanical parts used in various fields such as aerospace, automotive, or rail, construction.

[Prior art]

[003] Some parts or some parts of sets such as those mentioned above are sometimes asked to undergo mechanical stress or high mechanical stress. Such parts are therefore largely made of composite materials.

[004] A composite material is a blend of at least two immiscible components. A synergistic effect is obtained with such an assembly, so that the resulting composite material has particular mechanical and / or thermal and each of the initial component does not have or has but to a lesser degree relative to the composite material.

[005] In addition, a composite material is constituted by at least one reinforcing material imparting to said composite material has good mechanical properties, in particular good resistance to mechanical forces applied to the composite material, and a matrix material forming a continuous phase and ensuring the cohesion of the composite material. Among the different types of composites used in industry, composite organic matrix are the most represented. In the case of composite organic matrix, the matrix material is generally a polymer. This polymer may be either a thermosetting polymer or a thermoplastic polymer.

[006] The preparation of the composite material is effected by a mixture of the matrix material and the reinforcing material, or by wetting or impregnating the reinforcing material with the matrix material and then polymerizing the resulting system. In the case of the matrix mixture and a reinforcement, said reinforcement may be formed of reinforcing fillers such as gravel, sand, or glass beads. In the case of wetting or impregnating the reinforcement with the matrix, said reinforcement may be made of varying sizes fibers.

[007] The polymer matrix generally comprises a polymerization initiator to polymerize the polymer matrix impregnating the reinforcement material. This polymerization initiator is often in solid form, and therefore has the drawback of forming a solid deposit in the polymer matrix by decantation. The matrix is ​​therefore highly heterogeneous and subsequent polymerization, s' thereby effecting heterogeneous environment, does not allow to obtain composite materials having good mechanical properties. In addition, an initiator is in solid form can cause an obstruction of the supply lines of an injection molding machine used to synthesize the composite material, thereby causing the blocking, or even its breakage.

[008] A first solution may consist in dissolving the initiator in a solvent such as acetone, ethanol, or a phthalate, but this leads to high costs and the presence of an organic solvent is not desirable in such composite materials manufacturing processes. In addition, the rate of solvent required to solubilize the initiator is generally too high and inconsistent with syrup ratio (meth) acrylic initiator system machines. This is particularly the case with benzoyl peroxide (BPO) for which the syrup ratio (meth) acrylic acid / amount of syrup (meth) acrylic acid and the initiator system is less than or equal to 5%. possible

[009] An alternative solution is to use a liquid initiator. However, the kinetics of reactions implemented in the manufacturing processes of such composite materials is so much lower than in the case of using a solid starter, despite the presence of a polymerization accelerator. Among the liquid initiators, liquid peroxides are commonly used. Another disadvantage inherent in the use of liquid initiators such as peroxides liquids, is the fact that they can not be used in two-component system the first component being syrup

(Meth) acrylic acid and the second component being the initiator system, because the accelerator is stable in either of the two components.

[010] The document US 5,162,280 describes the production of an aqueous dispersion of aromatic diacyl peroxide, said aromatic diacyl peroxide is a polymerization initiator. This aqueous dispersion comprises more than one aromatic diacyl peroxide, a diluent consisting of an alkylene glycol and two suspending agents constituted respectively magnesium aluminum silicate, and a water soluble cellulose ether in water . Thus this document proposes a dispersion having an aromatic diacyl peroxide type initiator in liquid form. However, this document does not disclose the use of such a suspension for the manufacture of composite materials based on polymers.

[011] The document WO2010 / 112534 discloses an aqueous dispersion comprising from 35% to 45% by weight solid diacyl peroxide whose particles have a median diameter D50 between Ιμιτι and ΙΟμπι. The aqueous dispersion also comprises from 0.05% to 1% of dispersant, and an amount of less than 1% organic solvent.

[012] The document WO2014 / 135816 discloses a method of impregnating a fibrous substrate with a syrup (meth) acrylic polymer comprising a (meth) acrylic acid, a (meth) acrylic acid, and fillers selected from particles having a swelling ratio in the (meth) acrylic less than 200%, and the mean diameter D50 is less than 50μιτι. The polymerization of the syrup is carried out by adding an initiator which only the benzoyl peroxide in a slightly wet powder is described. This initiator is solid and is in the form of BPO powder and not an aqueous dispersion of organic peroxide in particular BPO.

[013] The document US 5,300,600 describes the production of an aqueous dispersion of normally solid aromatic peroxide at a temperature of 20 ° C, said aromatic peroxide as a polymerization initiator. This aqueous dispersion comprises other, more of an aromatic peroxide, a dispersing agent consisting of an alcohol made of polyester and an oxidised phenolic resin. However, this document does not disclose the use of such a suspension for the manufacture of composite materials based on polymers. On the other hand, the use of dispersing agent in the presence of normally solid initiator in an aqueous dispersion certainly provides a liquid composition, but the particle size of initiator in the composition is generally such that these particles can still come clog the feed lines of injection machines often necessary for the manufacture of composite materials. Furthermore, this type of liquid composition is generally unstable, which may lead in particular to lack of reproducibility of processes using said liquid composition. It may also be made to WO 2014013028 which the impregnation method has similar disadvantages to those mentioned above.

[Technical problem]

[014] The invention therefore aims to remedy the drawbacks of the prior art by providing a parts manufacturing process or part assembly based polymer composite material may be implemented on machines commonly used for molding said parts and / or parts of said sets of polymer-based composite material, without causing blockage or malfunction of such machines. The invention also aims a method for impregnating a fibrous substrate with a mixture of (meth) acrylic syrup comprising a (meth) acrylic acid and an aqueous dispersion free radical initiator consisting of an organic peroxide, said mixture can be placed implemented on machines commonly used for molding of said parts and / or parts of said sets of polymer-based composite material, without causing blockage or malfunction of such machines. The invention also aims to propose parts obtained by the method also having good mechanical properties.

[Brief description of the invention]

[015] To this end, the invention concerns a method of impregnating a fibrous substrate preferably consisting of long fibers, said method being primarily characterized in that it comprises a step of impregnating said fibrous substrate with a mixing (meth) acrylic liquid comprising:

a syrup (meth) acrylic polymer comprising at least one (meth) acrylic acid, and at least one (meth) acrylic acid, an aqueous dispersion comprising at least one radical initiator consisting of an organic peroxide to start the polymerization of (meth) acrylic, said at least one radical initiator having a particle size such that the median particle diameter by volume (D50) is between 1 and 30 μιτι μιτι, preferably between 2 and 25 μιτι μιτι, even more preferably between 3.5 μιτι and 20 μιτι, preferably between 3.5 and 15 μιτι μιτι, more preferably between 3.5 and 13 μιτι μιτι is even more preferably between 3 and 5μιτι 12μιτι.

[016] According to other optional features of the method of impregnation:

The step of impregnating the fibrous substrate is made in a closed mold,

The radical initiator is chosen from diacyl peroxides, peroxyesters, dialkyl peroxides, peroxyacetals or azo compounds,

The radical initiator comprises benzoyl peroxide (BPO),

The radical initiator content relative to the (meth) acrylic acid or the monomer mixture (meth) acrylic is between 100 and 50,000 ppm by weight, preferably between 200 and 40 000 ppm by weight and preferably between 300 and 30 000 ppm by weight,

The percentage by weight of radical initiator in the aqueous dispersion is between 30% and 80%, preferably between 35% and 70%, and even more preferably is between 35% and 60%,

The percentage by weight of radical initiator in the mixture (meth) acrylic acid is less than 5%, preferably less than 3%, and even more preferably has less than 2.5%,

The percentage by weight of radical initiator in the mixture (meth) acrylic acid is greater than 0.2%, preferably greater than 0.4%, and even more preferably greater than 0.5%,

The aqueous dispersion of radical initiator has a viscosity at 20 ° C of between 50 mPa · s and 1000 mPa * s, preferably 100 mPa · s and 750 mPa * s, and still more preferably 200 mPa * s and 500 mPa * s,

The radical initiator has a particle size such that the D10 diameter of volume particle is less than 20μιτι, preferably less than 15μιτι and even more preferably less than ΙΟμιτι,

The aqueous dispersion of radical initiator preferably comprises an emulsifying agent,

The aqueous dispersion of radical initiator preferably comprises a stabilizer,

Syrup (meth) acrylic liquid has a dynamic viscosity between 10 mPa · s and 10,000 mPa * s, preferably 50 mPa * s and 5000 mPa * s and preferably between 100 mPa.s and 1000 mPa.s, the dynamic viscosity being measured at 25 ° C,

The (meth) acrylic acid is methyl methacrylate homopolymer (MMA) or methyl methacrylate copolymer (MMA) or a mixture thereof,

Methyl methacrylate copolymer (MMA) comprises at least 70%, preferably at least 80%, preferably at least 90% and more preferably at least 95% by weight of methyl methacrylate (MMA),

Methyl methacrylate copolymer (MMA) comprises from 80% to 99.7%, advantageously from 90% to 99.7% and more preferably from 90% to 99.5% by weight methyl methacrylate and 0.3 % to 20%, preferably from 0.3% to 10% and more preferably from 0.5% to 10% by weight of at least one monomer containing at least one ethylenic unsaturation which can copolymerize with methyl methacrylate,

The (meth) acrylic acid in the mixture (meth) acrylic liquid is present in an amount of at least 10% by weight, preferably at least 15%, preferably at least 18% and more preferably at least 20% by weight of the mixture of (meth) acrylic total liquid,

The (meth) acrylic acid in the mixture (meth) acrylic liquid is present in an amount of at most 60% by weight, preferably at most 50%, preferably at most 40% and more preferably not more than 35% by weight of the mixture of (meth) acrylic total liquid,

The (meth) acrylic acid is selected from acrylic acid, methacrylic acid, alkyl acrylate monomers, alkyl methacrylate monomers and mixtures thereof, the alkyl group may be linear, branched or cyclic and containing 1 to 22 carbon atoms, preferably 1 to 12 carbon atoms,

The (meth) acrylic acid is selected from methyl methacrylate, ethyl methacrylate, methyl acrylate, 1 ethyl acrylate, methacrylic acid, acrylic acid, acrylate, n-butyl , acrylate, isobutyl methacrylate, n-butyl, isobutyl methacrylate, 1 'cyclohexyl acrylate, cyclohexyl methacrylate, 1 acrylate isobornyl methacrylate, isobornyl methacrylate and mixtures thereof,

The (meth) acrylic acid is selected from methyl methacrylate, isobornyl acrylate, acrylic acid and mixtures thereof,

50% by weight of (meth) acrylic or (meth) acrylic acid is methyl methacrylate,

Syrup (meth) acrylic acid comprises at least one filler and / or at least one additive such as modifiers of the impact resistance or block copolymers, heat stabilizers, UV stabilizers, flame retardants, lubricants, mold release agents, colorants, or mixtures thereof,

The additives are selected from modifiers of the impact resistance or block copolymers, heat stabilizers, UV stabilizers, flame retardants, lubricants, mold release agents, colorants, or mixtures thereof, and are present in the mixture (meth) acrylic liquid in an amount between 0.01% by mass and 50% by mass so that the dynamic viscosity of the syrup (meth) acrylic acid is between 10 mPa * s and 1000 mPa * s.

The fillers are selected from calcium carbonate (CaCO3), titanium dioxide (T1O2), and silica (S1O2), and are present in the aqueous dispersion in an amount between 0.01% by mass and 40% by mass so that the dynamic viscosity of the syrup (meth) acrylic liquid is between 10 mPa * s and 1000 mPa * s.

The mixture (meth) acrylic acid further comprises an activator in the syrup (meth) acrylic acid,

The activator is selected from tertiary amines such as N, -dimethyl-p-toluidine (DMPT), N, N-dihydroxyethyl-p-toluidine (DHEPT), transition metal catalysts soluble in the organic compounds or mixtures thereof,

The content of the activator relative to the (meth) acrylic syrup (meth) acrylic liquid is from 100 ppm to 10 000 ppm by weight, preferably from 200 ppm to 7000 ppm and preferably 300 ppm to 4000 ppm by weight,

The mixture (meth) acrylic acid comprises between 95% and 99% by weight, preferably between 96% and 98.5% by weight, and even more preferably between 97% and 98% by weight syrup (meth) acrylic acid, and between 1% and 5% by weight, preferably between 1.5% and 4% by weight, and even more preferably between 2% and 3% by weight aqueous dispersion.

[017] The invention further relates to a mixture of (meth) acrylic liquid for the implementation of the method of impregnating a fibrous substrate, said mixture being characterized in that it comprises:

a syrup (meth) acrylic polymer comprising at least one (meth) acrylic acid, and at least one (meth) acrylic acid,

an aqueous dispersion comprising at least one radical initiator consisting of an organic peroxide to start the polymerization of (meth) acrylic acid, said at least one radical initiator having a particle size such that the median particle diameter by volume (D50) is between 1 μιτι and 30 μιτι, preferably between 2 and 25 μιτι μπι and more preferably between 3.5 and 20 μιτι μιτι and advantageously between 3.5 and 15 μιτι μιτι.

[018] The invention further relates to a mechanical part of the manufacturing process or structured elements or articles, said method being primarily characterized in that it comprises the following steps:

a) impregnating a fibrous substrate with a mixture of (meth) acrylic liquid

b) polymerizing the mixture of (meth) acrylic liquid impregnating said fibrous substrate.

[019] According to other optional features of the manufacturing process:

The method further comprises, prior to step a), a mixture preparation stage (meth) acrylic liquid by mixing a syrup (meth) acrylic polymer comprising at least one (meth) acrylic acid, and at least one monomer (meth) acrylic acid and an aqueous dispersion comprising at least one radical of an organic peroxide initiator to start the polymerization of (meth) acrylic acid, said at least one radical initiator having a particle size distribution such that the median particle diameter volume (D50) is between 1 and 30 μιτι μιτι, preferably between 2 and 25 μιτι μιτι and even more preferably between 3.5 and 20 μιτι μιτι and advantageously between 3.5 and 15 μιτι μιτι, more preferably between 3 5 μιτι and 13 μιτι is even more advantageously between 3,5μιτι and 12μπι.

The impregnation of the fibrous substrate in step a) is performed in a closed mold,

Step a) and step b) are performed in the same closed mold,

The method is selected from transfer molding or resin infusion.

[020] The invention further relates to a mechanical or structural composite material part obtained by the manufacturing method. Said part may in particular be an automotive part, a boat room, a train room, a sports article, an airplane or helicopter room, a room or spacecraft rocket, a photovoltaic module piece , a wind turbine room, a piece of furniture, a component or building, room telephone or mobile phone, a computer room or TV room printer or copier

[Detailed description of the invention]

The method for impregnating a fibrous substrate

[021] The impregnation method of a fibrous substrate, comprises a step of impregnating said fibrous substrate with a mixture of (meth) acrylic acid wherein the mixture comprises:

a syrup (meth) acrylic liquid comprising at least a (meth) acrylic acid, and at least one (meth) acrylic acid,

an aqueous dispersion comprising at least one radical initiator. Advantageously, the radical initiator comprises an organic peroxide whose particle size is such that the median particle diameter by volume (D50) is between 1 and 30 μιτι μιτι, preferably between 2 and 25 μιτι μιτι and still more preferably between 3.5 and 20 μιτι μιτι and advantageously between 3.5 and 15 μιτι μιτι, more preferably between 3.5 and 13 μιτι μιτι is even more advantageously between 3,5μιτι and 12μιτι.

[022] The term "mixture of (meth) acrylic" refers to the polymeric matrix as described above. The sirup

(Meth) acrylic this mixture comprises is so named because of its liquid and viscous appearance, and may also be called prepolymer in that it comprises at least one monomer

(Meth) acrylic able to undergo polymerization to form a (meth) acrylic acid.

[023] The term "fibrous substrate" as used relates to fabrics, felts or nonwovens which may be in the form of strips, mats, braids, strands or pieces.

[024] The term "(meth) acrylic" as used refers to any type of acrylic and methacrylic monomers.

[025] The term "monomer" as used refers to a molecule that can undergo polymerization.

[026] The term "polymerization as used refers to the process of converting a monomer or a monomer mixture in a polymer.

[027] The term "composite material" as used refers to a multicomponent material comprising a plurality of different phase areas, including at least one type of phase domain is a continuous phase and wherein at least one component is a polymer .

[028] The term "initiator" as used refers to a chemical species which reacts with a monomer to form an intermediate compound capable of binding successfully to a number of other monomers to form a polymer compound.

[029] The term "D50" and "median diameter" the particle diameter that divides the particle distribution of a substance into two parts of equal areas. In the case of the median diameter D50 by volume, 50% of the total particle volume is the volume of particles of diameter less than D50, and 50% of the total particle volume is the volume of particles of diameter greater than D50.

[030] The term "D10" the particle diameter that divides the particle distribution of a substance into two parts of ratio of area 10% / 90%. In the case of D10 by volume, 10% of the total particle volume is the volume of particles of diameter less than D10, and 90% of the total particle volume is the volume of particles of diameter greater than D10.

The (meth) acrylic

[031] The (meth) acrylic acid can be selected from alkyl methacrylates or alkyl acrylates. According to a preferred embodiment, the (meth) acrylic acid is polymethyl methacrylate (PMMA). It should be therefore understood that polymethyl methacrylate (PMMA) may designate a methyl methacrylate homopolymer (MMA) or a copolymer of MMA or mixtures thereof.

[032] In particular, it may be a mixture of at least two homopolymers of MMA having a different molecular weight, or a mixture of at least two MMA copolymers having a composition identical monomers and different molecular weight, or a mixture of at least two MMA copolymers having a composition different monomers. It can also be a mixture of at least a MMA homopolymer and at least one copolymer of MMA.

[033] According to one embodiment, the copolymer of MMA comprises at least 70%, preferably at least 80%, preferably at least 90% and more preferably at least 95% by weight of methyl methacrylate. MMA copolymer can also comprise from 0.3 to 30% by weight of at least one monomer containing at least one ethylenic unsaturation and being capable of copolymerizing with methyl methacrylate. Among such monomers there may be mentioned: acrylic and methacrylic acids and (meth) acrylates in which the alkyl group contains from 1 to 12 carbon atoms. For example, there may be mentioned methyl acrylate and (meth) acrylate, butyl or 2-ethylhexyl. Preferably the comonomer is an alkyl acrylate wherein the alkyl group contains from 1 to 4 carbon atoms.

[034] According to a preferred embodiment, the methyl methacrylate copolymer (MMA) comprises from 80% to 99.7%, advantageously from 90% to 99.7% and more preferably from 90% to 99.5% by weight methyl methacrylate and 0.3% to 20%, preferably from 0.3% to 10% and more preferably from 0.5% to 10% by weight of at least one monomer containing at least one ethylenic unsaturation which may be copolymerized with methyl methacrylate. Preferably, the comonomer is selected from methyl acrylate or ethyl acrylate or mixtures thereof.

[035] The polymer (meth) acrylic syrup in the (meth) acrylic liquid are present in an amount of at least 10% by weight, preferably at least 15%, preferably at least 18% and more preferably at least 20% by weight of the syrup (meth) acrylic total liquid.

[036] The polymer (meth) acrylic syrup in the (meth) acrylic liquid are present in an amount of at most 60% by weight, preferably at most 50%, preferably at most 40% and more advantageously at most 35% by weight of the syrup (meth) acrylic total liquid.

[037] The average molecular weight of the (meth) acrylic acid is generally high, and can be therefore greater than 50 000 g / mol, preferably greater than 100 000 g / mol.

The average molecular weight can be measured by steric exclusion chromatography (SEC).

The (meth) acrylic

[038] The monomer (s) (meth) acrylic acid (s) included in the syrup (meth) acrylic polymer in addition to the (meth) acrylic acid can (wind) be selected (s) from acrylic acid, methacrylic acid, acrylic monomers alkyl, methacrylic monomers alkyl and mixtures thereof.

[039] Preferably, the (meth) acrylic acid is selected from acrylic acid, methacrylic acid, acrylic monomers alkyl, methacrylic monomers alkyl and mixtures thereof, the alkyl group may be linear, branched or cyclic and containing 1 to 22 carbon atoms, preferably 1 to 12 carbon atoms.

[040] Advantageously, the (meth) acrylic acid is selected from methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, methacrylic acid, acrylic acid, acrylate, n-butyl acrylate, isobutyl

methacrylate, n-butyl, isobutyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl methacrylate, isobornyl and mixtures thereof.

[041] More preferably, the (meth) acrylic acid is selected from methyl methacrylate, isobornyl acrylate or acrylic acid and mixtures thereof.

[042] According to a preferred embodiment, at least 50% by weight, preferably at least 60% by weight of (meth) acrylic or (meth) acrylic acid is methyl methacrylate.

[043] According to one embodiment of more preferred at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight and advantageously at least 80% by weight and even more preferably 90 % by weight of (meth) acrylic acid is methyl methacrylate mixture with isobornyl acrylate and / or acrylic acid.

[044] The (meth) acrylic or (meth) acrylic syrup (meth) acrylic liquid are present in an amount of at least 40% by weight, preferably 50% by weight, preferably 60% by weight and more preferably 65% ​​by weight of the syrup (meth) acrylic total liquid.

The fibrous substrate

[045] With regard to the fibrous substrate, there may be mentioned fabrics, felts or nonwovens which may be in the form of strips, mats, braids, strands or pieces. The fibrous material can have different shapes and sizes, one-dimensional, two-dimensional or three-dimensional. A fibrous substrate comprises an assembly of one or more fibers. When the fibers are continuous, their assembly form tissues.

[046] The one-dimensional shape corresponds to the linear fibers. The fibers can be discontinuous or continuous. The fibers may be arranged randomly or in the form of a continuous filament in parallel to each other. A fiber is defined by its ratio of length, which is the ratio between the length and diameter of the fiber. The fibers used in the present invention are long fibers or continuous fibers. The fibers have an aspect ratio of at least 1000, preferably at least 1500, more preferably at least 2000, preferably at least 3000 and most preferably of at least 5 000.

[047] The two-dimensional shape corresponds to the fibrous mats or nonwoven reinforcement or woven rovings or bundles of fibers, which can also be braided.

[048] The three-dimensional shape corresponds for example fibrous mats or nonwoven reinforcement or bundles of fibers or mixtures thereof, stacked or folded assembly of the two-dimensional shape in the third dimension.

[049] The origins of the fibrous material may be natural or synthetic. As a natural material, there may be mentioned vegetable fibers, wood fibers, animal fibers or mineral fibers.

[050] Natural fibers such as sisal, jute, hemp, flax, cotton, coconut fiber and banana fibers. Animal fibers such as wool or hair.

[051] As a synthetic material, there may be mentioned polymeric fibers selected from thermoset polymer fibers, thermoplastic polymer or mixtures thereof.

[052] The polymer fibers may be made of polyamide (aromatic or aliphatic), polyester, polyvinyl alcohol, polyolefins, polyurethanes, polyvinyl chloride, polyethylene, unsaturated polyesters, epoxy resins and esters vinyl.

[053] The mineral fibers may also be chosen from glass fibers, in particular of type E, R or S2, carbon fibers, boron fibers or silica fibers.

[054] The fibrous substrate of the present invention is selected from vegetable fibers, wood fibers, animal fibers, mineral fibers, synthetic polymeric fibers, glass fibers, carbon fibers or mixtures thereof. Preferably, the fibrous substrate is selected from the inorganic fibers.

The aqueous dispersion

[055] The mixture (meth) acrylic acid comprises an aqueous dispersion comprising at least one initiator for initiating polymerization of the monomer (s) (meth) acrylic acid (s) included in the syrup (meth) acrylic acid and more of the polymer (s) (meth) acrylic acid (s).

[056] The aqueous dispersion comprising at least one initiator for initiating polymerization is not a load, as the initiator responds to start the polymerization.

[057] One can for example mention the initiators or initiator systems that are activated by heat. The initiator activated by heat is preferably a radical initiator. Said free radical initiator may be selected from diacyl peroxides, peroxyesters, dialkyl peroxides, peroxyacetals or azo compounds.

[058] Preferably, the initiator is chosen from carbonate, isopropyl, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, dicumyl peroxide, perbenzoate, tert-butyl per (2- ethylhexanoate), tert-butyl,

1 hydroperoxide, cumyl hydroperoxide, 1, 1-di (tert-butylperoxy) -3, 3, 5-trimethylcyclohexane, peroxy-tert-butyl peracetate, tert-butyl perpivalate, tert-butyl perpivalate d amyl peroctoate, tert-butyl,

1 azobisisobutyronitrile (AIBN), 1 'azobisisobutyramide, 2,2'-azobis (2, 4-dimethylvaleronitrile) or the acid 4, 4-azobis (4-cyanopentanoic). Using a mixture of radical initiators selected from the above list would not be outside the scope of the invention.

[059] Preferably, the initiator is selected from peroxides containing 2 to 20 carbon atoms. More preferably, the initiator is benzoyl peroxide (BPO).

[060] The radical initiator content relative to the (meth) acrylic acid or the monomer mixture (meth) acrylic syrup (meth) acrylic liquid is between 100 and 50 000 ppm by weight (50,000 ppm = 5% by weight), preferably between 200 and 40 000 ppm by weight and preferably between 300 and 30 000 ppm by weight.

[061] The aqueous dispersion preferably comprises between 30% and 80%, preferably between 35% and 70%, and even more preferably between 35% and 60% of radical initiator. Such an aqueous dispersion having a high content of organic peroxide helps to ensure optimal and complete polymerization of the mixture (meth) acrylic acid.

[062] The aqueous dispersion preferably comprises between 0.01% and 10%, preferably between 0.05% and 7%, and even more preferably between 0.1% and 5% of a surfactant.

[063] The aqueous dispersion preferably comprises between 0.01% and 10%, preferably between 0.05% and 7%, and even more preferably between 0.1% and 5% of a stabilizer.

[064] According to one embodiment of the invention, the percentage by mass of the radical initiator in the mixture (meth) acrylic syrup comprising (meth) acrylic acid and the dispersion of radical initiator is less than 5%, preferably less than 3%, and even more preferably less than 2.5%.

[065] The viscosity of the aqueous dispersion of radical initiator is between 50 mPa * s and 1000 mPa * s, preferably 100 mPa · s and 750 mPa * s, and still more preferably 200 mPa * s and 500 mPa · s, said viscosity being measured at 20 ° C, 50 rpm. The viscosity can be measured with a rheometer or viscometer, for example Brookfield type viscometer such as the Brookfield DVII.

[066] Furthermore, the particle size of the initiator of the aqueous dispersion is such that the median particle diameter in volume

(D50) is between 1 and 30 μιτι μιτι, preferably between 2 and 25 μιτι μιτι and even more preferably between 3.5 and 20 μιτι μιτι and advantageously between 3.5 and 15 μιτι μιτι, more preferably between 3 5 μιτι and 13 μιτι is even more advantageously between 3,5μιτι and 12μπι.

[067] Such a particle size allows to obtain a homogeneous dispersion of the initiator in water, thus promoting the impregnation of the fibrous substrate by mixing said dispersion comprising

and aqueous syrup (meth) acrylic acid. The homogeneity of the dispersion also allows an optimum and complete polymerization of the syrup (meth) acrylic acid after impregnating the fibrous substrate with said syrup (meth) acrylic acid.

[068] Such polymerization according to the invention leads to high molecular weight, generally greater than 100 000 g / mol, preferably greater than 500 000 g / mol and even more preferably greater than 1 000 000 g / mol. Such molecular weight values ​​make it possible to obtain a composite material with very good mechanical properties.

[069] Such a particle size also provides an aqueous dispersion of permanent radical initiator so that the initiator is completely soluble in said aqueous dispersion in the mixture and (meth) acrylic syrup obtained after mixing

(Meth) acrylic acid and said aqueous dispersion.

[070] The aqueous dispersion according to the invention, before being mixed with the syrup (meth) acrylic acid to form the mixture

(Meth) acrylic acid, does not obstruct the feeding of the injection machine lines used for the implementation of the method of impregnating the fibrous substrate and / or mechanical parts of the manufacturing process or structured elements or articles made of composite material according to the invention, and is not adapted to obstruct said supply of the injection machine lines.

[071] In addition, after mixing the aqueous dispersion according to the invention with the syrup (meth) acrylic acid to form the mixture

(Meth) acrylic acid, said mixture of (meth) acrylic acid does not obstruct the injection lines of the injection machine used for the implementation of the method of impregnating the fibrous substrate and / or mechanical parts manufacturing process or structured elements or articles made of composite material according to the invention, and is not adapted to obstruct said injection lines of the injection machine.

[072] An advantage of such an aqueous dispersion of radical initiator according to the invention is its good dissolution in the syrup (meth) acrylic acid, to form a mixture of (meth) acrylic homogeneous. It is thus possible to use a static mixer for mixing the aqueous dispersion of radical initiator with syrup (meth) acrylic acid. It is of course possible to use other types of mixers suitable for the realization of such a mixture, such as a mechanical mixer, or a rotating pan mixer.

[073] Another advantage of such an aqueous dispersion of radical initiator according to the invention is to enable a homogeneous polymerization of the mixture (meth) acrylic acid. In particular, the polymerization is uniform throughout the volume of the mold used for the method of impregnating the fibrous substrate and / or to the parts manufacturing process of composite material, thus resulting in the formation of regular pieces having a number of imperfections reduced compared with the composite material parts obtained by a different manufacturing method from that described herein.

[074] The (meth) acrylic acid or the mixture of (meth) acrylic acid as defined above may optionally be accompanied by a suitable inhibitor to prevent said (meth) acrylic acid from polymerizing spontaneously. Such an inhibitor may be incorporated into the syrup (meth) acrylic acid. Suitable inhibitors may be mentioned in particular 1 hydroquinone (HQ), methyl hydroquinone (MEHQ), 2,6-di-tert-butyl-4-methoxyphenol (Topanol 0) and 2, 4-dimethyl-6-tert butylphenol (Topanol A).

[075] The mixture (meth) acrylic acid may further comprise an activator for the polymerization, said enhancer can be incorporated into the syrup (meth) acrylic acid.

[076] The polymerization activator or accelerator is selected from tertiary amines such as N, -dimethyl-p-toluidine

(DMPT), N, -dihydroxyéthyl-p-toluidine (DHEPT), transition metal catalysts soluble in the organic compounds or mixtures thereof.

[077] Advantageously, the syrup (meth) acrylic liquid does not contain catalysts based on metals.

[078] The content of the activator relative to the (meth) acrylic syrup (meth) acrylic liquid is from 100 ppm to 10 000 ppm by weight, preferably from 200 ppm to 7000 ppm and preferably 300 ppm to 4000 ppm by weight.

[079] The presence of activators or accelerators depends upon the final application. When cold cure is required or desired, an accelerator is generally required. Cold cure means that the polymerization takes place at room temperature, or in general at a temperature below 40 ° C. However, for industrial applications, it is possible to heat polymerization at a higher temperature at from 40 ° C.

[080] The mixture (meth) acrylic acid may also comprise a chain-limiting agent in order to regulate the molecular weight of the polymer (s) formed. It may for example γ-terpinene or terpinolene. The content of the limiting agent is generally between 0 and 500 ppm and preferably between 0 and 100 ppm, based on the (meth) acrylic monomer mixture or (meth) acrylic syrup (meth) acrylic acid.

[081] The mixture (meth) acrylic acid may also comprise other additives and fillers. A charge is not considered as an additive in the context of the present invention. Such fillers and additives may be incorporated into the syrup (meth) acrylic acid. In addition, additives and / or fillers may be added to the mixture of (meth) acrylic acid prior to impregnation.

[082] As additives there may be mentioned organic additives such as modifiers of the impact resistance or block copolymers, heat stabilizers, UV stabilizers, lubricants and mixtures thereof.

[083] The modifier of the impact resistance is in the form of fine particles having an elastomer core and at least one thermoplastic shell, the particle size being generally less than 1 μιτι and advantageously between 50 and 300 μιτι. The modifier of the impact strength is prepared by emulsion polymerization. The content of the modifier of the impact resistance in the syrup (meth) acrylic liquid is 0 to 50% by weight, preferably from 0 to 25% by weight and preferably 0 to 20% by weight.

[084] Preferably, the additives are selected from modifiers of the impact resistance or block copolymers, heat stabilizers, UV stabilizers, flame retardants, lubricants, mold release agents, colorants, or mixtures thereof.

[085] The additives are present in the mixture (meth) acrylic acid in an amount between 0.01% by mass and 50% by mass so that the dynamic viscosity of the syrup (meth) acrylic acid is between 10 mPa * s and 1000 mPa * s at 20 ° C.

[086] As fillers, there may be mentioned carbon nanotubes or inorganic fillers, including mineral nanofillers (Ti0 2 , silica).

[087] Preferably, the fillers are selected from calcium carbonate (CaCO3), titanium dioxide (T1O2), and silica (Si0 2 ).

[088] The fillers are present in the aqueous dispersion in an amount between 0.01% by mass and 40% by mass so that the dynamic viscosity of the mixture of (meth) acrylic liquid is between 10 mPa * s and 1000 mPa * s at 20 ° C.

[089] Furthermore, advantageously the mixture of (meth) acrylic acid comprises between 95% and 99% by weight, preferably between 96% and 98.5% by weight, and even more preferably between 97% and 98% by weight of syrup (meth) acrylic acid, and between 1% and 5% by weight, preferably between 1.5% and 4% by weight, and even more preferably between 2% and 3% by weight aqueous dispersion.

The manufacturing process for the production of mechanical parts or structural elements or articles

[090] The method comprises the steps of:

a) impregnating a fibrous substrate with a mixture of (meth) acrylic liquid,

b) polymerizing the mixture of (meth) acrylic liquid impregnating said fibrous substrate.

[091] The impregnation of the fibrous substrate in step a) is preferably carried out in a closed mold. Advantageously, step a) and step b) are carried out in the same mold closed.

[092] The mechanical parts or structural elements or articles made from composite material can be obtained according to various methods. Infusion may be mentioned the vacuum bag molding, the molding pressure bag molding in an autoclave, the resin transfer molding (RTM), injection molding, reaction (RIM), injection molding -réaction reinforced (R-RIM) and its variants, the press molding or compression molding.

[093] The preferred manufacturing processes for the manufacture of mechanical parts or structural elements or articles based composite material are processes wherein the mixture of (meth) acrylic liquid is transferred to the fibrous substrate by impregnating said fibrous substrate in a mold, more preferably in a closed mold.

[094] Advantageously, the manufacturing process is selected from transfer molding or resin infusion.

[095] All methods include the step of impregnating the fibrous substrate with the mixture of (meth) acrylic liquid before the curing step in a mold. The polymerization of the mixture of step (meth) acrylic liquid impregnating said fibrous substrate takes place after the impregnation step in the same mold.

[096] The transfer molding resin is a method using a mold assembly in which two sides form the both surfaces of a composite material. The lower side is a rigid mold. The upper side may be a rigid or flexible mold. Flexible molds can be made from composite materials, silicone or extruded polymeric films such as nylon. The two sides interlock to form a mold cavity. The distinctive characteristic of the transfer molding resin is that the fibrous substrate is placed in this cavity and the mold assembly is closed before the introduction of syrup (meth) acrylic liquid. Transfer molding resin comprises numerous variations which differ in the mechanical introduction of syrup (meth) acrylic liquid at the fibrous substrate in the mold cavity. These variations range from vacuum infusion to the transfer molding resin under vacuum (VARTM). This process can be carried out at ambient or elevated temperature.

[097] With the process of infusion, syrup (meth) acrylic liquid must have the viscosity suitable for the material of the polymer composite preparation process. Syrup (meth) acrylic liquid is sucked into the fibrous substrate present in a special mold by applying a slight vacuum. The fibrous substrate is infused and completely impregnated with the syrup (meth) acrylic liquid.

[098] An advantage of this method is the large amount of fibrous material in the composite.

[099] For the implementation of the impregnation method of the fibrous substrate and / or the piece manufacturing method of composite material, it is possible to use an injection machine having a first input is fed by the syrup ( meth) acrylic acid, and a second input is fed by the dispersion of radical initiator. The syrup and the dispersion are then routed to a mixer where they are mixed to obtain a mixture

(Meth) acrylic substantially homogeneous, and then injected into a mold in which is previously deposited a fibrous substrate. Said fibrous substrate is impregnated with the mixture (meth) acrylic acid, then the obtained polymerization system can form a composite material part.

[0100] Preferably, the output rate, that is to say, the injection rate of the mixture (meth) acrylic into the mold, is less than 4 kg / minute, preferably less than 3.4 kg / minute.

[0101] Regarding the use of mechanical parts or structured elements or articles manufactured, automotive applications can be mentioned, marine applications, railway applications, sports, aerospace and aeronautical applications, applications photovoltaic, computer applications, applications for telecommunications and applications for wind energy.

[0102] The mechanical parts include automotive parts, boat parts, train parts, sporting goods, aircraft or helicopter parts, spacecraft parts or rocket parts photovoltaic module of wind parts, furniture parts, construction or building parts, parts of telephone or cell phone, computer parts or television, printer and photocopier room.

[Examples]

[0103] A syrup (meth) acrylic acid is prepared by dissolving

25 parts by weight of a copolymer (PMMA - ethyl polyacrylate) BS520 of the type in 75 parts by weight of methyl methacrylate stabilized with MEHQ (monomethyl ether of hydroquinone), and 0.5 part by weight of N, -dihydroxyéthyl-p-toluidine (DHEPT). Syrup (meth) acrylate thus obtained is referred to as component A.

[0104] We prepared three different formulations of benzoyl peroxide (BPO), BPO being referred to as component B. The various formulations, designated by 1 BPO BPO 2, BPO and 3, are indicated in Table I below. The viscosity of these formulations was measured using a Brookfield type viscometer at 50 rpm and at 20 ° C. The particle size and the diameter D50 BPO dispersions or suspensions is measured by laser diffraction using a HELOS SUCELL apparatus of the company Sympatec GmbH. The different formulations of BPO are sold under the trademarks Luperox ANS50G, Luperox ® A40FP-EZ9 and Perkadox® L-40RPS, by Arkema.

[0105] Tableau I : formulations de BPO

[0106] The methacrylic syrup (component A) and the different formulations of BPO (component B) mentioned above may be used for the RTM molding method by using the injection machine PatriotTM Pro Thermoplastic Resin Injection System, manufactured by the company Magnum Venus Products, Kent (WA). It is a pneumatic machine running with a maximum compressed air pressure of 7 bar, with loops recirculation and cleaning systems for each component. The output rate up to 3.4 kg per minute, the volume of component B content relative to component A is between 1.0% and 4.5%.

[0107] The mixture of (meth) acrylic liquid syrup comprising (meth) acrylic acid and one of the above formulations is injected into a closed mold comprising a glass fabric as a fibrous substrate, and polymerized at 25 ° C for 40 to 50 minutes. - With the formulation BP01, only two rooms were realized. Thereafter, the machine jammed. The main filter and injection pipes were clogged.

With the formulation BP02, a range of 30 pieces was conducted over several days, requiring no work on the machine.

With the formulation BP03, the filter of the machine is clogged after a few minutes of operation, requiring shutdown and complete cleaning of the machine before restart.

CLAIMS

A method for impregnating a fibrous substrate, said method being characterized in that it comprises a step of impregnating said fibrous substrate with a mixture of (meth) acrylic liquid comprising:

- a syrup (meth) acrylic polymer comprising at least one (meth) acrylic acid, and at least one (meth) acrylic acid,

- an aqueous dispersion comprising at least one radical initiator consisting of an organic peroxide to start the polymerization of (meth) acrylic acid, said at least one radical initiator having a particle size such that the median particle diameter by volume (D50) is between 1 and 30 μιτι μιτι, preferably between 2 and 25 μιτι μιτι and even more preferably between 3.5 and 20 μιτι μιτι and advantageously between 3.5 and 15 μιτι μιτι, more preferably between 3.5 and 13 μιτι μιτι is even more preferably between 3,5μιτι and 12μιτι.

Impregnation method according to claim 1, characterized in that the step of impregnating the fibrous substrate is made in a closed mold.

Impregnation method according to claim 1 or 2, characterized in that the radical initiator is chosen from diacyl peroxides, peroxyesters, dialkyl peroxides, peroxyacetals or azo compounds.

Impregnation process according to any one of claims 1 to 3, characterized in that the radical initiator comprises benzoyl peroxide (BPO).

Impregnation process according to any one of claims 1 to 4, characterized in that the radical initiator content relative to the (meth) acrylic monomer mixture or (meth) acrylic is between 100 and 50 000 ppm weight, preferably between 200 and

40 000 ppm by weight and preferably between 300 and 30 000 ppm by weight.

Impregnation process according to any one of claims 1 to 5, characterized in that the percentage by weight of radical initiator in the aqueous dispersion is between 30% and 80%, preferably between 35% and 70%, and most even more preferably is between 35% and 60%.

Impregnation process according to any one of claims 1 to 6, characterized in that the percentage by weight of radical initiator in the mixture (meth) acrylic acid is less than 5%, preferably less than 3%, and even more less than 2.5% preferred.

Impregnation process according to any one of claims 1 to 7, characterized in that the aqueous dispersion of radical initiator has a viscosity at 20 ° C of between 50 mPa · s and 1000 mPa * s, preferably 100 mPa * s and 750 mPa.s, and even more preferably between 200 mPa.s and 500 mPa.s.

Impregnation process according to any one of claims 1 to 8, characterized in that the (meth) acrylic acid is methyl methacrylate homopolymer (MMA) or methyl methacrylate copolymer (MMA) or a mixture thereof .

Impregnation method according to claim 9, characterized in that the methyl methacrylate copolymer (MMA) comprises at least 70%, preferably at least 80%, preferably at least 90% and more preferably at least 95% by weight methyl methacrylate (MMA).

Impregnation method according to claim 9, characterized in that the methyl methacrylate copolymer (MMA) comprises from 80% to 99.7%, advantageously from 90% to 99.7% and more preferably from 90% to 99, 5% by weight of methyl methacrylate and from 0.3% to 20%, preferably from 0.3% to 10% and more preferably from 0.5% to 10% by weight of at least one monomer containing at least one ethylenic unsaturation which can copolymerize with methyl methacrylate.

Impregnation process according to any one of claims 1 to 11, characterized in that the polymer

(Meth) acrylic acid in the mixture (meth) acrylic liquid is present in an amount of at least 10% by weight, preferably at least 15%, preferably at least 18% and more preferably at least 20% by weight of the mixture

(Meth) acrylic total liquid.

Impregnation process according to any one of claims 1 to 12, characterized in that the polymer

(Meth) acrylic acid in the mixture (meth) acrylic liquid is present in an amount of at most 60% by weight, preferably at most 50%, preferably at most 40% and more preferably at most 35% by weight of the mixture

(Meth) acrylic total liquid.

4. The method for impregnating according to any one of claims 1 to 13, characterized in that the mixture (meth) acrylic comprises further activator.

Impregnation method according to claim 14, characterized in that the activator is selected from tertiary amines such as N, -dimethyl-p-toluidine (DMPT), N, N-dihydroxyethyl-p-toluidine (DHEPT) , transition metal catalysts soluble in the organic compounds or mixtures thereof.

6. The method for impregnating according to claim 14 or 15, characterized in that the content of the activator relative to the (meth) acrylic syrup (meth) acrylic liquid is from 100 ppm to 10,000 ppm (by weight) , preferably from 200 ppm to 7000 ppm by weight and preferably from 300 ppm to 4000 ppm.

Impregnation process according to any one of claims 1 to 16, characterized in that the mixture

(Meth) acrylic acid comprises between 95% and 99% by weight, preferably between 96% and 98.5% by weight, and even more preferably between 97% and 98% by weight syrup

(Meth) acrylic acid, and between 1% and 5% by weight, preferably between 1.5% and 4% by weight, and even more preferably between 2% and 3% by weight aqueous dispersion.

8. Mixture (meth) acrylic liquid for the implementation of the method of impregnating a fibrous substrate according to any one of claims 1 to 17, said mixture (meth) acrylate being characterized in that it comprises:

a syrup (meth) acrylic acid comprising at least one polyme (meth) acrylic acid, and at least one (meth) acrylic acid,

- an aqueous dispersion comprising at least one radical initiator consisting of an organic peroxide to start the polymerization of (meth) acrylic acid, said at least one radical initiator having a particle size such that the median particle diameter by volume (D50) is between 1 and 30 μιτι μιτι, preferably between 2 and 25 μιτι μιτι and even more preferably between 3.5 and 20 μιτι μιτι and advantageously between 3.5 and 15 μιτι μιτι, more preferably between 3.5 and 13 μιτι μιτι is even more preferably between 3,5μιτι and 12μιτι.

9. A method of manufacture of mechanical parts or structural elements or articles, said method being characterized in that it comprises the following steps:

- a) impregnating a fibrous substrate with a mixture of (meth) acrylic liquid Seion any one of claims 1 to 17 with a mixture of (meth) acrylic liquid according to claim 18,

- b) polymerizing the mixture of (meth) acrylic liquid impregnating said fibrous substrate.

A manufacturing method according to claim 19, characterized in that it further comprises, prior to step a), a mixture forming step (meth) acrylic liquid by mixing a syrup (meth) acrylic acid comprising at least a (meth) acrylic acid, and at least one (meth) acrylic acid, and an aqueous dispersion comprising at least one radical of an organic peroxide initiator to start the polymerization of (meth) acrylic acid, said at least one radical initiator having a particle size such that the median particle diameter by volume (D50) is between 1 and 30 μιτι μιτι, preferably between 2 and 25 μιτι μιτι and even more preferably between 3.5 and 20 μιτι μιτι and advantageously between 3.5 and 15 μιτι μπι.

1. A manufacturing method according to claim 19 or 20, characterized in that the impregnation of the fibrous substrate in step a) is performed in a closed mold.

2. The manufacturing method according to any one of claims 19 to 21, characterized in that step a) and step b) are carried out in the same mold closed.

3. The manufacturing method according to any one of claims 19 to 22, characterized in that the method is selected from transfer molding or resin infusion.

4. mechanical or structural composite material part obtained by the manufacturing method according to claims 19 to 23.

5. Part according to claim 24, said part being an automotive part, a boat part, a gear part, a sports article, a part airplane or helicopter, a spaceship or rocket piece , a module piece

photovoltaic, wind a piece, a piece of furniture, a component or building, room telephone or mobile phone, a computer room or TV, printer or photocopier room.