EP1885774A2

EP1885774A2 - Use of a particular composition for producing parts by filament winding

Info

Publication number: EP1885774A2
Application number: EP06764705A
Authority: EP
Inventors: Laurent Gervat; Nicolas Passade-Boupat
Original assignee: Arkema France SA
Current assignee: Arkema France SA
Priority date: 2005-06-01
Filing date: 2006-05-31
Publication date: 2008-02-13
Also published as: CN101223214A; WO2006129014A2; FR2886644B1; US20080308214A1; JP2008542493A; FR2886644A1; WO2006129014A3; KR20080019030A

Abstract

The invention relates to the use of a composition for producing parts by filament winding, which comprises at least one type of resin formulation containing at least one type of thermosetting resin, at least one type of miscible rheology regulating agent which provides the composition with a viscosity difference whose factor is equal to or greater than 100 between a high-temperature state at a C1 shear rate and a low temperature state at a C2 shear rate, wherein the difference in temperature between the high-temperature and low-temperature states is equal to or greater than 30 °C, the C1 shear rate is greater than the C2 shear rate and the composition exhibits a Newtonian behaviour in the high-temperature state thereof.

Description

USE OF A PARTICULAR COMPOSITION FOR THE MANUFACTURE OF PARTS THROUGH FILAMENT WINDING

DESCRIPTION TECHNICAL FIELD

The present invention relates to the use of a composition comprising the combination of a thermosetting resin and a particular polymer for producing composite materials by filament winding.

The present invention also relates to a method for preparing parts by filament winding from said composition.

The general field of the invention is therefore that of composite materials.

The composite materials result from the intimate association:

a reinforcement, which constitutes the reinforcement or the skeleton, ensuring the mechanical strength of the material, this reinforcement being filamentary in nature (mineral or organic fibers); and a matrix, which binds the reinforcing fibers, distributes the forces (resistance to bending or compression) and provides chemical protection, in addition giving the shape of the produced product, this matrix comprising an organic resin. The two elements (reinforcement and matrix) have qualities that combine with synergy.

By playing on the nature of the reinforcement and the matrix, one can thus access materials presenting a very great diversity of mechanical and chemical properties.

This is the reason why composite materials find a very large number of applications in many fields, such as aeronautics, the automotive industry, the shipbuilding industry, and construction. STATE OF THE PRIOR ART

To manufacture composite parts, dozens of techniques are now known among which can be mentioned, among others: contact molding, projection molding, autoclave draping, low pressure molding ... etc.

In a number of cases, especially when it is desired to obtain hollow and large pieces, it may be advantageous to work directly with rolled fibers. These fibers can be used in pre-impregnated form with a resin. However, these fibers are expensive and have a limited life, given the difficulty of conservation of these fibers, without a phenomenon of polymerization of the resin does not intervene. This is why it may be interesting, to make hollow parts, to implement the technique of filament winding, which uses, initially, dry fibers.

More specifically, the technique of filament winding consists in first passing the dry fibers through a bath comprising a resin and then, in a second step, winding them on a mandrel of shape adapted to the workpiece. to manufacture. The piece thus obtained by winding is cured during a final step, for example, by heating.

The difficulty of this technique lies in the step of impregnating the dry fibers. Indeed, for a satisfactory impregnation, it is necessary that the composition is sufficiently liquid to properly impregnate the fiber without causing sagging during the bath exit of the fiber.

The compositions used up to now do not prevent this phenomenon of sagging. This phenomenon is responsible for a significant loss of composition, inhomogeneous deposits on the surface of the fibers and soiling of the tools.

There is therefore a real need for compositions that do not have the following drawbacks.

The inventors have discovered, surprisingly, that by incorporating, in a composition comprising a resin formulation, a polymer having particular rheological characteristics, it was possible to overcome the disadvantages of the compositions of the prior art used to make parts. by filament winding. SUMMARY OF THE INVENTION

Thus, the invention relates, according to a first object, to the use of a composition for making filament winding parts, said composition comprising: at least one resin formulation comprising at least one thermosetting resin;

at least one rheology regulator miscible in said formulation such that it confers on the composition a viscosity difference of at least a factor of 100 between a high temperature state with a shear rate Ci and a low temperature gradient state. shear C ₂ , the temperature difference between the high temperature state and the low temperature state being at least 30 ⁰ C and the shear rate Ci being greater than the shear rate C ₂ ; and

- that the composition has a Newtonian behavior in the high temperature state. It is specified that, according to the invention, the shearing gradient Ci results from the speed of passage of the fiber to be impregnated in the bath comprising the composition while the high temperature state corresponds to the temperature prevailing in the bath, this temperature ranging from , generally from 40 to 150 ^° C., for example from 80 to 100 ^° C.

It is specified that the shear gradient C ₂ results from the residual slip of the composition deposited on the fiber, outside the composition bath, this gradient being therefore much lower than Ci, while the "low temperature" state qualifies the temperature prevailing outside the bath when the fiber is fed from the bath to the mandrel.

Due to a significant difference in viscosity between the high temperature state and the low temperature state of the composition, the flow phenomena at the outlet of the bath with fibers coated with this composition are markedly reduced, as well as the soiling on the surfaces. various elements of the process. The deposit thus remains uniform on the fibers. It follows after winding the fibers on a mandrel and hardening,. a uniform distribution of the mechanical and physical properties of the resulting composite material.

In addition, because the compositions of the invention have a Newtonian character in the "high temperature" state, that is to say that their viscosity does not vary substantially with the speed of solicitation of the mixture, it is possible obtaining fibers coated in an equivalent manner (i.e. with a substantially identical amount of composition and a uniform distribution of the composition) regardless of the rate of passage of the fiber into the bath comprising the composition. Finally, since the abovementioned rheological characteristics (viscosity, Newtonian character) are induced mainly by the addition of the rheology regulating agent as defined above in the solution, this allows a greater freedom of choice. of the resin formulation. Advantageously, the rheology regulating agent induces a viscosity difference between the high temperature state and the low temperature state by a factor of at least 500, and not generally exceeding 10 ⁵ , for example, for a difference in temperature between the high temperature state and the low temperature state of at least 60 ° C.

By way of example, the abovementioned compositions have a viscosity of less than 1 Pa.s at 100 ^° C. (composition bath temperature) and a viscosity of about 1000 Pa.s at room temperature (the ambient temperature corresponding to the temperature of the room in which the filament winding process takes place).

The rheology regulators may be polymers, for example, linear or branched.

In particular, the rheology control agents may be block copolymers, at least one of which blocks is incompatible with said resin formulation.

According to a particular embodiment of the invention, polymers conferring on the compositions the above-mentioned rheological characteristics may be block copolymers comprising:

at least one block M miscible with said resin formulation;

at least one block B incompatible with said resin formulation and said block M-. Block M is a polymer miscible with the resin formulation.

M may be a homopolymer of methyl methacrylate. M can also be a copolymer of methyl methacrylate.

For example, M may be a copolymer of methyl methacrylate and at least one water-soluble monomer. This -copolymer may comprise at least 20% by weight of methyl methacrylate, preferably at least 50% by weight of methyl methacrylate and a water-soluble monomer.

By way of example of water-soluble monomers, mention may be made of acrylic or methacrylic acid, amides derived from these acids such as, for example, dimethylacrylamide, 2-methoxyethyl (meth) acrylate, and 2-aminoethyl (meth) acrylates. optionally quaternized, (meth) acrylates of polyethylene glycol (PEG), water-soluble vinyl monomers such as N-vinylpyrrolidone or any other monomer soluble in water.

Advantageously, the polyethylene glycol group of polyethylene glycol (meth) acrylates has a mass ranging from 400 g / mol to 10,000 g / mol.

Preferably, the water-soluble monomer is dimethylacrylamide.

The proportion of methyl methacrylate may be in moles of 10 to 95%, preferably 60 to 90%, for 90 to 5%, preferably 40 to 10%, of water-soluble monomer.

In addition, the block M may comprise other monomers, such as acrylic monomers or not, reactive or not. By reactive monomer is meant: a chemical group capable of reacting with the oxirane functions of the epoxy molecules or with the chemical groups of the hardener. By way of non-limiting examples of reactive functional groups, mention may be made of: oxirane functions, amine functional groups and carboxy functional groups. The reactive monomer may be (meth) acrylic acid or any other hydrolysable monomer leading to these acids. Among the other monomers that can constitute the M block, mention may be made, by way of nonlimiting examples, of glycidyl methacrylate or tert-butyl methacrylate, n-butyl acrylate.

Block B is a polymer incompatible with the resin formulation and with block M. Advantageously the Tg of B is less than 0 ^° C. and preferably less than -40 ^° C. The monomer used to synthesize block B can be a diene selected from butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-phenyl-1,3-butadiene. B is advantageously chosen from poly (dienes), especially poly (butadiene), poly (isoprene) and their random copolymers, or else from partially or completely hydrogenated poly (dienes). Among the polybutadienes, it is advantageous to use those with the lowest Tg, for example 1,4-polybutadiene of Tg (around -80 ^° C.), lower than that of polybutadiene-1,2 (around 0 ^° C.). Blocks B can also be hydrogenated. This hydrogenation is carried out according to the usual techniques. The monomer used to synthesize block B can also be a

alkyl (meth) acrylate (in other words, block B may be an alkyl poly (meth) acrylate) such as

Ethyl acrylate (Tg = -24 ° C), n-butyl acrylate (Tg = -45 ° C), 2-ethylhexyl acrylate (Tg = -60 ° C), n-octyl acrylate (Tg = -62 ° C), I ¹ hydroxyethyl acrylate (Tg = -15 ° C) and 2-ethylhexyl methacrylate (Tg = -10 ° C). Advantageously, n-butyl acrylate is used. The acrylates are different from those of the M block to meet the requirement of incompatible B and M. Preferably, the blocks B consist mainly of polybutadiene-1, 4. B is incompatible with the thermosetting resin and with the block M. According to a particular embodiment, the rheology regulating agent is a triblock copolymer MBM, B and M being blocks as defined above.

The two blocks M of the triblock copolymer M-B-M may be identical or different. When they are different, they may be different by the nature of the monomers constituting them or different by their molar mass but consisting of the same monomers.

The triblock copolymer MBM has a number-average molar mass which may be between 10,000 g / mol and 500,000 g / mol, preferably between 20000 and 200000 g / mol. Advantageously, the MBM triblock has the following compositions in M and B, expressed in mass fraction, the total being 100%: M: between 10% and 80%, preferably between 15 and 70%; B: between 90 and 20% and preferably between 85% and 30%.

A particular M-B-M triblock copolymer is a copolymer in which: the M blocks represent a copolymer comprising the methyl methacrylate monomer and the dimethylacrylamide monomer;

block B is a homopolymer consisting of the n-butyl acrylate monomer, the M blocks possibly also comprising the n-butyl acrylate monomer.

Another suitable M-B-M triblock copolymer is a copolymer in which: the M blocks represent a polymer comprising the methyl methacrylate monomer;

The copolymers used as rheology control agent may comprise, in addition to the blocks B and M, an S block incompatible with said resin formulation and the B block. S is incompatible with the thermosetting resin and with the block B. The Tg or Tf of S is advantageously greater than the Tg of B and at 23 ^° C. and preferably greater than 50 ° C. Examples of blocks S include those derived from vinylaromatic compounds such as styrene, α-methyl styrene, vinyltoluene, and those derived from alkyl esters of acrylic and / or methacrylic acids having 1 to 18 carbon atoms in the alkyl chain. Preferably, the block S is a polystyrene.

According to a particular embodiment of the invention, the rheology regulating agent is a triblock copolymer S-B-M, S, B and M being blocks as defined above. The triblock copolymer S-B-M has a number-average molar mass which may be between 10,000 g / mol and 500,000 g / mol, preferably between 20000 and 200000 g / mol. Advantageously, the triblock copolymer S-B-M has the following compositions in S, M and B, expressed in mass fraction, the total being 100%:

M: between 10% and 80%, preferably between 15 and 70%; B: between 2 and 80% and preferably between 5% and 70%; S: between 10 and 88% and preferably between 15 and 85%.

According to the invention, part of the S-B-M can be replaced by an S-B diblock. This portion may represent up to 70% by weight of the copolymer.

A particular SBM triblock copolymer is a copolymer comprising: a block S consisting of a homopolymer consisting of the styrene monomer;

a block B consisting of a homopolymer consisting of the 1,4-butadiene monomer; a block M consisting of a homopolymer consisting of the methyl methacrylate monomer.

According to another embodiment of the invention, the polymers which can be used as a rheology regulator and which confer on the compositions containing them the above-mentioned rheological characteristics may be block copolymers comprising:

at least one block B incompatible with said resin formulation;

at least one block S incompatible with said resin formulation and block B.

Blocks S and B may be as defined above.

In particular, these copolymers can be diblock copolymers S-B, in which: the block S consists of a homopolymer consisting of the styrene monomer; - Block B consists of a homopolymer consisting of 1,4-butadiene monomer.

The compositions used according to the invention comprise a resin formulation comprising at least one thermosetting resin. Preferred thermosetting resins are epoxy resins.

By epoxy resin, hereinafter denoted by E, is meant any organic compound having at least two functions of oxirane type, polymerizable by ring opening. The term "epoxy resins" refers to all the usual epoxy resins that are liquid at room temperature (23 ^° C.) or at a higher temperature. These epoxy resins can be monomeric or polymeric on the one hand, aliphatic, cycloaliphatic, heterocyclic or aromatic on the other hand. By way of examples of such epoxy resins, mention may be made of diglycidyl ether of resorcinol, diglycidyl ether of bisphenol A, triglycidyl p-amino phenol, diglycidyl ether of bromo-bisphenol F, triglycidyl ether of m-amino phenol, tetraglycidyl methylene dianiline, triglycidyl ether

(trihydroxyphenyl) methane, novolac phenol-formaldehyde polyglycidyl ethers, orthocresol novolac polyglycidyl ethers and tetraphenyl ethane tetraglycidyl ethers. Mixtures of at least two of these resins may also be used.

Epoxy resins having at least 1.5 oxirane functions per molecule and more particularly epoxy resins containing between 2 and 4 oxirane functions per molecule are preferred. Epoxy resins having at least one aromatic ring, such as diglycidyl ethers of bisphenol A, are also preferred.

The resin formulation generally comprises a hardener. With regard to the hardener, mention may be made of:

acid anhydrides, among which mention may be made of succinic anhydride; aromatic or aliphatic polyamines, among which mention may be made of diamino diphenyl sulphone (DDS), methylene dianiline, 4,4 '-Methylenebis- (3-chloro-2,6-diethylaniline) (MCDEA), 4 4'-methylenebis (2,6-diethylaniline) (MDEA); dicyandiamide and its derivatives;

imidazoles;

polycarboxylic acids;

polyphenols.

It would not be outside the scope of the invention to add in the composition conventional additives, such as thermoplastics such as polyethersulfones, polysulfones, polyetherimides, polyphenylene ethers, liquid elastomers or impact modifiers of the heart-bark type. .

The composition of the invention may be prepared by mixing the resin formulation and the rheology regulator with any conventional mixing techniques. It will be possible to use all the thermoplastic techniques making it possible to achieve a homogeneous mixture between the two parts of the thermosetting resin and the control agent such as extrusion. With regard to the proportion of the resin formulation and the regulating agent of rheology, the proportion of the agent is preferably from 5 to 20% by weight for 95 to 80% by weight of the resin formulation. Preferably, the content of the agent is preferably 5 to 15% by weight for 95 to 85% by weight of the resin formulation.

As mentioned above, the compositions described are used for the preparation of parts by filament winding. Thus, the invention relates, according to a second object, to a method of manufacturing a workpiece by filament winding comprising successively:

a step of passing fibers intended to constitute the reinforcement of the part in a bath comprising a composition comprising at least one resin formulation comprising a thermosetting resin;

a step of winding the fibers thus coated onto a mandrel of suitable shape; a step of hardening the wound fibers, characterized in that the composition further comprises at least one rheology regulator miscible with said formulation such that it confers on the composition a difference in viscosity of a factor of at least 100 between a high temperature state with a shear rate C ₁ and a low temperature state with a shear rate C ₂ , the temperature difference between the high temperature state and the low temperature state being at least 30 ^° C. and the shear rate Ci being greater than the shear rate C ₂ ; and - that the composition has a Newtonian behavior in the high temperature state.

The rheology regulator is as defined above.

Thus, according to one particular embodiment of the invention, the rheology regulating agent may be a block copolymer comprising:

at least one block M miscible with said resin formulation;

at least one block B incompatible with said resin formulation and said block M.

Blocks M and B are as defined above. According to another embodiment, the rheology regulating agent may be a block copolymer comprising:

at least one block B incompatible with said resin formulation; at least one block S incompatible with said resin formulation and block B.

Blocks B and S are as defined above.

The fibers intended to constitute the reinforcement of the part may be glass fibers, carbon fibers or even aramid fibers.

In the first instance, these fibers are conveyed from a reeling creel to an impregnation bath, where they are coated with the composition described above. _{± η} - _ _^

In a second step, they are conveyed by a guidance system to the aforementioned mandrel and then deposited thereon.

Once the deposition operation is complete, the coated fibers are subjected to a hardening step, which can take place:

at room temperature; by heating, for example, in an oven; or by induction by ultraviolet or infrared radiation.

The hardening step will depend mainly on the nature of the hardener introduced into the composition.

The composition used according to the invention can be applied for the manufacture of parts in a very large number of areas. Thus, the invention relates to parts obtained by the aforementioned method, said parts can be intended for aeronautics, the shipbuilding industry, construction, the manufacture of wind turbines, the manufacture of tubes for the transport of fluids, for example, in factories in the chemical industry or for the transport of hydrocarbons.

Finally, the invention relates to a composition for the manufacture of parts by filament winding, the composition being as defined above. Thus, according to one particular embodiment of the invention, the rheology regulating agent may be a block copolymer comprising:

at least one block M miscible with said resin formulation;

at least one block B incompatible with said resin formulation and said block M.

Blocks B and S are as defined above.

The invention will now be described with respect to the following examples given for illustrative and not limiting.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 represents a graph illustrating the evolution of the Eta * viscosity (in Pa · s) at a loading frequency of 6.28 rad.s ^-1 as a function of the temperature (in C ⁰ ) d a composition as illustrated in Example 1. FIG. 2 represents a graph illustrating the evolution of the Eta * viscosity (in Pa · s) as a function of the loading frequency (in rad.s ^" ^τ ) at 80 ^° C. and 100 ^° C. of a composition such as illustrated in Example 1.

FIG. 3 represents a graph illustrating the evolution of the Eta * viscosity (in Pa · s) as a function of the loading frequency (in rad.s ^" ^x ) at 20 ° C. and 30 ^° C. of a composition such as illustrated in Example 1.

FIG. 4 represents a graph illustrating the evolution of the Eta * viscosity (in Pa · s) at a loading frequency of 6.28 rad.s ^-1 as a function of the temperature (in ^O C) of a composition such as as illustrated in Example 2.

FIG. 5 represents a graph illustrating the evolution of the Eta * viscosity (in Pa · s) as a function of the loading frequency (in rad.s ^' ^x ) at 80 ^° C. and 100 ^° C. of a composition such as illustrated in Example 2.

FIG. 6 represents a graph illustrating the evolution of the Eta * viscosity (in Pa · s) as a function of the stress frequency (in rad.s ^" ^• * ^• ) at 20 ^° C. and 30 ^° C. of a composition as illustrated in Example 2. FIG. 7 represents a graph illustrating the evolution of the Eta * viscosity (in Pa · s) at a loading frequency of 6.28 rad.s ^-1 as a function of the temperature (in ^O C) of a composition such as as illustrated in Example 3.

FIG. 8 represents a graph illustrating the evolution of the Eta * viscosity (in Pa · s) as a function of the loading frequency (in rad.s ^" ^x ) at 90 ^° C. and HO ⁰ C of a composition such as illustrated in Example 3.

FIG. 9 represents a graph illustrating the evolution of the Eta * viscosity (in Pa · s) as a function of the loading frequency (in rad.s ^" ^α ) at 20 ^° C. and 30 ° C. of a composition such that illustrated in Example 3.

FIG. 10 represents a graph illustrating the evolution of the Eta * viscosity (in Pa · s) at a loading frequency of 6.28 rad.s ^-1 as a function of the temperature (in ^° C.) of two resins such as illustrated in Example 3.

FIG. 11 represents a graph illustrating the evolution of the Eta * viscosity (in Pa · s) as a function of the stress frequency (in rad.s ^" ^{x '} ) at 25 ^° C. of two resins as illustrated in FIG. example 3. ^ _χ

FIG. 12 represents a graph illustrating the evolution of the Eta * viscosity (in Pa · s) as a function of the stress frequency (in rad.s ^"

¹ ) at 85 ^° C. of two resins as illustrated in Example 3.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

EXAMPLE 1

In this example, the copolymer used is an SBM triblock copolymer in which:

the block S is a homopolymer consisting of the styrene monomer; block B is a homopolymer consisting of 1,4-butadiene monomer;

the block M is a homopolymer consisting of the monomer methyl methacrylate.

More specifically, this copolymer has the molecular characteristics:

* S block content: 55% by total weight of ^'copolymer; * Block content B: 15% of the total weight of the copolymer;

* Block content M: 30% of the total weight of the copolymer;

* Weight average molecular weight Mw of block S: 20150 *% by weight of the SB polymer relative to SBM: 36% by weight relative to the total weight of the copolymer.

This copolymer is present in the composition at a content of 15% by weight relative to the total weight of the composition.

The tested composition further comprises: - bisphenol diglycidyl ether resin

A (DER 332® sold by Dow) is a 4,4'-methylenebis (2,6-diethylaniline) amine (MDEA) sold by the company Lonza under the trade name LONZACURE, the resin and the amine being present at a temperature of 85% by weight of the total weight of the composition.

The protocol for producing the composition is the following: Dow's DER 332 resin is stirred at

16O ⁰ C in a capacity;

as soon as the temperature is stabilized, the resin is degassed by evacuation;

after degassing, the evacuation is stopped and the SBM copolymer is introduced in powder form;

when all the SBM is dissolved in the epoxy resin, the mixture is degassed by evacuation; after degassing, the temperature is lowered to 120 ° C. and the evacuation is stopped; the amine MDEA is introduced in stoichiometric quantity with respect to the epoxy resin, ie with a ratio r = (amine mass / resin mass) = 0.445.

This composition is perfectly adapted to be used according to the filament winding method, as illustrated in FIG. 1, which shows the evolution of the viscosity of this composition as a function of temperature.

Thus, the composition shows a viscosity of 1.5 Pa. S at 80 ⁰ C and 0.4 Pa. S at 100 ⁰ C. This viscosity range, within this temperature window is perfectly adapted to the coating of a carbon or glass fiber according to the filament winding method.

Moreover, in this temperature window the mixture has a Newtonian character, that is to say that its viscosity does not vary with the speed of stressing of the mixture, as illustrated in FIG. 2.

This behavior is an important advantage since, at all speeds of travel of the fiber in the bath of the product, it will produce an equivalent coating.

Advantageously, this composition also shows a very significant change in viscosity with temperature, unlike the compositions of the prior art, which are maintained with a relatively low viscosity when leaving the bath. It follows that, when the coated fiber leaves the bath, coulure phenomena can occur, which will be the cause of change in the amount of product deposited on the fiber but also possible soil on the various elements of the process.

In the case of the composition of this example, these types of problems will not occur since the viscosity of the composition increases sharply when the temperature drops.

Very advantageously, the composition also changes rheological behavior when the temperature drops, having a pseudoplastic character at low temperature. The pseudoplastic character of the composition results in a marked increase in viscosity, when the shear gradient decreases, which is the case of the fiber coated with the composition at the outlet of the bath, insofar as the gradient of Shearing is only due to the weight of the composition.

FIG. 3 shows this pseudoplastic character on the measurements at 20 ^° C. and 30 ^° C.

Thus, at 20 ^° C., the composition of this example has a viscosity of more than 1000 Pa.s at a loading frequency of 6.28 rad.s ^-1 .

EXAMPLE 2

In this example, the copolymer used is a MBM copolymer in which: the blocks M represent a copolymer comprising the monomer methyl methacrylate and the monomer dimethylacrylamide;

block B is a homopolymer consisting of the n-butyl acrylate monomer.

More specifically, this copolymer has the following molecular characteristics:

* Content of n-butyl acrylate: 53% by weight of the total weight of the copolymer;

^ Content of methyl methacrylate: 31%

* Dimethylacrylamide content: 16%

* Average molecular weight in number Mn of block B: 23780

* Ip polydispersity index of block B: 1.4

This copolymer is present in the composition at a content of 5% by weight relative to the total weight of the composition.

The composition used comprises, in addition:

an RTMβ epoxy resin from Hexcel; the resin being present at a content of 95% by weight of the total weight of the composition.

The protocol for producing the composition is as follows: the RTMβ resin of Hexcel is stirred at 100 ^° C. in a capacity;

as soon as the temperature is stabilized, the resin is degassed by evacuation; after degassing, the evacuation is stopped and the copolymer is introduced in powder form;

when all the copolymer is dissolved in the epoxy resin, the mixture is degassed by evacuation.

This composition is perfectly adapted to be used according to the filament winding method, as illustrated in FIG. 4, which shows the evolution of the viscosity of this composition as a function of temperature.

Thus, the composition shows a viscosity of 1.8 Pa.s at 80 ° C. and 0.6 Pa.s at 100 ^° C. This range of viscosity in this temperature window is perfectly adapted to the coating of a carbon or glass fiber according to the filament winding method.

Moreover, in this temperature window the mixture has a Newtonian character, that is to say that its viscosity does not vary with the speed of stressing of the mixture, as illustrated in FIG. 5.

This behavior is an important advantage since, at all speeds of scrolling fiber in the bath of the product, it will produce an equivalent coating.

Very advantageously, this composition also shows a very significant change in viscosity with temperature, unlike the compositions of the prior art, which are maintained with a relatively low viscosity when leaving the bath. It follows that, when the coated fiber leaves the bath, coulure phenomena can occur, which will be the cause of change in the amount of product deposited on the fiber but also possible soil on the various elements of the process.

In the case of the composition of this example, these types of problems will not occur since the viscosity of the composition increases sharply when the temperature drops and the composition changes rheological behavior, having a pseudo-plastic character at low temperature. .

The pseudo-plastic nature of the composition results in a marked increase in viscosity, when the shear gradient decreases, which is precisely the case of the fiber coated with the composition at the outlet of the bath, since the gradient shear is only due to the weight of the composition. FIG. 6 shows this pseudoplastic character on the measurements at 20 ^° C. and 30 ^° C. At 20 ° C., the composition of this example has a viscosity of more than 1000 Pa.s at a loading frequency of 6.28 rad.s ^-1 .

EXAMPLE 3

In this example, the copolymer used is an M-B-M copolymer in which: the M blocks represent a polymer comprising the methyl methacrylate monomer; and

block B is a homopolymer consisting of the n-butyl acrylate monomer.

More specifically, this copolymer has the following molecular characteristics:

* Content of n-butyl acrylate: 42% by weight of the total weight of the copolymer;

* Content of methyl methacrylate: 58%

* Average molecular weight in number Mn of block B: 21200

* Polydispersity index Ip of block B: 1.3.

This copolymer is present in the composition at a content of 10% by weight relative to the total weight of the composition.

The composition used comprises, in addition: an epoxy resin RTM6 from Hexcel, the resin being present at a content of 90% by weight of the total weight of the composition.

The protocol for producing the composition is as follows:

the RTMβ resin of Hexcel is stirred at 100 ^° C. in a capacity;

as soon as the temperature is stabilized, the resin is degassed by evacuation;

after degassing, the evacuation is stopped and the copolymer is introduced in powder form;

This composition is perfectly adapted to be used according to the filament winding method, as illustrated in FIG. 7, which shows the evolution of the viscosity of this composition as a function of temperature.

Thus, the composition shows a viscosity of 2.3 Pa. S at 90 ⁰ C and 0.8 Pa. S to 110 ⁰ C. This viscosity range, within this temperature window is perfectly adapted to the coating of a carbon or glass fiber according to the filament winding method. Moreover, in this temperature window the mixture has a Newtonian character, that is to say that its viscosity does not vary with the speed of stressing of the mixture, as illustrated in FIG.

In the case of the composition of this example, these types of problems will not occur since the viscosity of the composition increases dramatically when the temperature drops and the composition changes of rheological behavior, having a character ^at low pseudoplastic temperature. The pseudoplastic character of the composition results in a marked increase in viscosity when the shear rate ^"decreases, which is the case of the coated fiber of the composition at the outlet of the bath, insofar as the shear gradient is only due to the weight of the composition.

FIG. 9 shows this pseudoplastic character on the measurements at 20 ^° C. and at 30 ^° C. At 30 ^° C., the composition of this example has a viscosity of more than 1000 Pa · s at a loading frequency of 6.28 rad. .s ^{' 1} .

FIG. 10 shows the evolution of the viscosity as a function of temperature for the resin DER 332 as well as for the RTMβ. Figure 11 shows viscosities at 25 ° C and Figure 12 at 85 ° C for both resins. They are outside the range best suited for a filament winding process and have a Newtonian behavior, even at low temperature. The above table illustrates the viscosity values at 25 ^° C. and 85 ° C. for these two resins.

Claims

Use of a composition for making filament winding parts, said composition comprising: at least one resin formulation comprising at least one thermosetting resin;

at least one rheology regulator miscible in said formulation such that it confers on the composition a difference in viscosity of at least 100 between a high temperature state with a shear rate Ci and a low temperature state with shear rate C ₂ , the temperature difference between the high temperature state and the low temperature state being at least 30 ^° C. and the shearing gradient Ci being greater than the shear gradient C ₂ ; and

- that the composition has a Newtonian behavior in the high temperature state.

2. Use of a composition according to claim 1, wherein the temperature difference between the high temperature state and the low temperature state is at least 60 ^° C.

3. Use of a composition according to claim 1 or 2, wherein the difference in viscosity is at least a factor of 500.

4. Use of a composition according to any one of claims 1 to 3, wherein the rheology regulating agent is a block copolymer, at least one of which blocks is incompatible with said resin formulation.

5. Use of a composition for making filament winding parts, said composition comprising: at least one resin formulation comprising at least one thermosetting resin; and

at least one rheology regulating agent chosen from block copolymers comprising:

at least one block M miscible with said resin formulation; and

at least one block B incompatible with said resin formulation and said block M.

6. Use of a composition according to claim 5, wherein M is a homopolymer of methyl methacrylate or a copolymer of methyl methacrylate.

7. Use of a composition according to claim 5 or 6, wherein M is a copolymer of methyl methacrylate and at least one water-soluble monomer.

8. Use of a composition according to claim 1, wherein in M, the molar proportion of methyl methacrylate is 10 to 95% for 90 to 5% of water-soluble monomer.

9. Use of a composition according to claim 7 or 8, wherein the molar proportion of methyl methacrylate is from 60 to 90% to 40 to 10% of water-soluble monomer.

Use of a composition according to any of claims 7 to 9, wherein the water-soluble monomer is dimethylacrylamide.

11. Use of a composition according to any one of claims 5 to 10, wherein the block B is selected from alkyl poly ((meth) acrylates) and polydienes.

12. Use of a composition according to any one of claims 5 to 11, wherein the B block is a n-butyl polyacrylate block.

13. Use of a composition according to any of claims 5 to 12, wherein the rheology regulator is a M-B-M triblock copolymer.

14. Use of a composition according to claim 13, wherein the copolymer is an M-B-M copolymer in which:

the blocks M represent a copolymer comprising the monomer methyl methacrylate and the monomer dimethylacrylamide; block B is a homopolymer consisting of the n-butyl acrylate monomer, the M blocks possibly also comprising the n-butyl acrylate monomer.

15. Use of a composition according to claim 13, wherein the copolymer is an M-B-M copolymer in which: the M blocks represent a polymer comprising the monomer methyl methacrylate;

16. Use of a composition according to any one of claims 5 to 12, wherein the block copolymer further comprises an S block incompatible with said resin formulation and block B.

17. Use of a composition according to claim 16, wherein the S block is a polystyrene.

18. Use of a composition according to claim 16 or 17, wherein the copolymer is an S-B-M copolymer comprising:

a block S consisting of a homopolymer consisting of the styrene monomer; a block B consisting of a homopolymer consisting of the 1,4-butadiene monomer;

a block M consisting of a homopolymer consisting of the methyl methacrylate monomer.

19. Use of a composition for making filament winding parts, said composition comprising: at least one resin formulation comprising at least one thermosetting resin; and

at least one rheology regulating agent chosen from block copolymers comprising:

at least one block B incompatible with said resin formulation; and * at least one S block incompatible with said resin formulation and block B.

Use of a composition according to claim 19, wherein the rheology regulator is a diblock copolymer S-B, wherein: the S block is a homopolymer consisting of the styrene monomer; Block B consists of a homopolymer consisting of 1,4-butadiene monomer.

21. Use of a composition according to any one of claims 1 to 20, wherein the thermosetting resin is an epoxy resin.

22. Use of a composition according to claim 21, wherein the epoxy resin is chosen from resorcinol diglycidyl ether, bisphenol A diglycidyl ether, triglycidyl p-amino phenol, bromo-bisphenol F diglycidyl ether, triglycidyl ether m-aminophenol, tetraglycidyl methylene dianiline, triglycidyl ether

(trihydroxyphenyl) methane, novolac phenol-formaldehyde polyglycidyl ethers, orthocresol novolac polyglycidyl ethers and tetraphenylethane tetraglycidyl ethers.

23. Use of a composition according to any one of claims 1 to 22, wherein the resin formulation comprises a hardener.

24. Use of a composition according to claim 23, wherein the hardener is selected from acid anhydrides, aromatic or aliphatic polyamines, diacyandiamide, imidazoles, polycarboxylic acids, polyphenols.

25. A method of manufacturing a piece by filament winding comprising successively:

a step of passing fibers intended to constitute the reinforcement of the part in a bath comprising a composition comprising at least one resin formulation comprising a thermosetting resin; a step of winding the fibers thus coated onto a mandrel of suitable shape; a step of hardening the wound fibers, characterized in that the composition further comprises at least one rheology regulator miscible in said formulation such that it gives the composition a difference in viscosity of a factor of from minus 100 between a high temperature state with a shear rate Ci and a low temperature state with a shear rate C ₂ , the temperature difference between the high temperature state and the low temperature state being at least 30 ^° C. and the shear gradient

C _α being greater than the shear rate C ₂ ; and - the composition has a Newtonian behavior in the high temperature state.

26. A method of manufacturing a filament winding part comprising successively: - a fiber passage step for constituting the reinforcement of the piece in a bath comprising a composition comprising at least one resin formulation comprising a thermosetting resin; a step of winding the fibers thus coated onto a mandrel of suitable shape; a step of hardening the wound fibers, characterized in that the composition further comprises at least one rheology control agent selected from block copolymers comprising: at least one block M miscible with said resin formulation;

at least one block B incompatible with said resin formulation and said block M.

27. A method of manufacturing a piece by filament winding comprising successively:

a step of winding the fibers thus coated onto a mandrel of suitable shape; a step of hardening the wound fibers, characterized in that the composition further comprises at least one rheology control agent chosen from block copolymers comprising: at least one block B incompatible with said resin formulation; and

at least one block S incompatible with said resin formulation and block B.

28. A process according to any one of claims 25 to 27, wherein the fibers are selected from glass fibers, carbon fibers, aramid fibers and mixtures thereof.

29. Part obtained by a process as defined in any one of claims 25 to 28.

30. Part according to claim 29, which is a part for aeronautics.

31. Part according to claim 29, which is a tube for transporting fluids.

32. A composition for the manufacture of filament winding parts comprising: at least one resin formulation comprising at least one thermosetting resin; and at least one rheology regulator miscible in said formulation such that it gives the composition a viscosity difference of at least 100 between a high temperature state with a shear rate Ci and a low temperature state at a shear rate C ₂ , the temperature difference between the high temperature state and the low temperature state being at least 30 ^° C. and the shearing gradient Ci being greater than the shear gradient C ₂ ; and - the composition has a Newtonian behavior in the high temperature state.

33. A composition for the manufacture of filament winding parts comprising: at least one resin formulation comprising at least one thermosetting resin; and at least one rheology regulating agent chosen from block copolymers comprising:

at least one block M miscible with said resin formulation; and * at least one block B incompatible with said resin formulation and said block M.

34. A composition for the manufacture of filament winding parts comprising: - at least one resin formulation comprising at least one thermosetting resin; and

at least one rheology regulating agent chosen from block copolymers comprising:

at least one block B incompatible with said resin formulation; and

at least one block S incompatible with said resin formulation and block B.