[Field of the invention]
[001]The present invention relates to an impregnation process for
a fibrous substrate, a liquid composition for implementing this
process and the obtained impregnated fibrous substrate. The
impregnated fibrous substrate is suitable for manufacturing
10 mechanical or structured parts or articles.
[002] In particular the present invention deals with an industrial
process for impregnating a fibrous substrate or long fibers with a
viscous liquid composition containing mainly methacrylic or
acrylic components. This viscous composition is called hereafter
15 liquid (meth) acrylic syrup. The invention concerns also a fibrous
substrate pre-impregnated with said syrup which is useful for
manufacturing mechanical or structured parts or articles.
[003]More particular the impregnation of fibrous substrate with
the (meth) acrylic syrup is achieved in a closed mould.
20 [004]The present invention concerns also manufacturing process for
manufacturing mechanical or structured parts or articles and threedimensional
mechanical or structured parts obtained by this
process.
2 5 [Technical problem]
[005]Mechanical or structured parts or articles that have to
absorb high stresses during their use are widely manufactured from
composite materials. A composite material is a macroscopic
combination of two ore more non miscible materials. The composite
30 material constitutes at least of a matrix material that forms a
continuous phase for the cohesion of the structure and a
reinforcing material with various architectures for the mechanical
properties.
[006]The aim in using composite materials is to achieve a
35 performance from the composite material that is not available from
its separate constituents if used alone. Consequently composite
materials are widely used in several industrial sectors as for
example building, automotive, aerospace, transport, leisure,
electronics, and sport notably due to their better mechanical
performance (higher tensile strength, higher tensile modulus,
higher fracture toughness) in comparison with homogenous materials
5 and their low density.
[007]The most important class in view of volume in commercial
industrial scale, are composites with organic matrices, where the
matrix material is a generally polymer. The principal matrix or
continuous phase of a polymeric composite material is either a
10 thermoplastic polymer or a thermosetting polymer.
[008]Thermosetting polymers consist of crosslinked three
dimensional structures. The crosslinking is obtained by curing
reactive groups inside the so called prepolymer. Curing for
15 example can be obtained by heating the polymer chains in order to
crosslink and harden the material permanently.
[009]In order to prepare the polymeric composite material the
prepolymer is mixed with the other component such as glass beads
or fibres or the other component which is wetted or impregnated
20 and cured afterwards. Example for prepolymers or matrix material
for thermoset polymers are unsatured polyesters, vinylesters,
epoxy or phenolic ones.
[010] A major disadvantage of a thermoset polymer matrix is its
rigidity. The matrix cannot be easily shaped in other forms. Once
25 the polymer has been cured the form is fixed. This makes also
difficult the recycling of the thermoset composite material and
manufactured mechanical or structured parts or articles comprising
said thermoset composite material, which are burned in a cement
plant or thrown into a waste dump.
3 0
[Oll]Thermoplastic polymers consist of linear or branched
polymers, which are not crosslinked. The thermoplastic polymers
are heated in order to mix the constituents necessary for
producing the composite material and to be cooled for setting. The
35 limit in using thermoplastic polymers for the fabrication of
composite materials is their high viscosity in the molten state in
order to hornogenously impregnating for example a fibrous
substrate. The wetting or correct impregnation of the fibers by
the thermoplastic polymer can only be achieved, if the
thermoplastic resin is sufficiently fluid. In order to have a low
viscosity or sufficient fluidity of the thermoplastic polymer the
5 chain length or molecular mass shall be reduced. However a too low
molecular weight has a negative impact on the performance of the
composite material and on the mechanical or structured parts
especially their mechanical properties as the deformation modulus.
[012] Another way to reduce the viscosity in an important way of
10 the thermoplastic polymer is to increase the temperature.
Consequently the continuous working temperature is relatively
high, above 2 0 0 " ~in~c reasing the economics costs of the composite
material and mechanical or structured parts due to implication of
high energy costs. Additionally thermoplastic polymers tend to
15 degrade if the temperature is too high, which is especially true
for semicrystalline thermoplastic polymers that have high melting
points as for example polyamides such as PA6.6, polyethersulfon
(PES) , polyetherimid ( P E I ) , polyetheretherketon (PEEK) or
polyphenylene sulfide (PPS) . This thermoinduced degradation yields
20 to a decreasing molecular welght of the polymer matrix on the
fibrous substrate important for the cohesion of the composite
material and the mechanical or structured parts.
[013] Another way for impregnating the fibrous substrate is to
dissolve the thermoplastic polymer in an organic solvent. However
25 this method requires a lot of solvent that has to be evaporated.
There are environmental issues in using large quantities of
solvent in term of energy and pollution.
[014]These are the limits or disadvantages for the preparation of
thermoplastic composite materials especially wlth fibrous
30 reinforcements, the impregnation process for a fibrous substrate
and the manufactured mechanical or structured parts or articles
comprising said thermoplastic composite material.
I0151 The objective of the present invention is to solve the
35 disadvantages mentioned above.
[016]One objective of the present invention is to have a
structural part comprising a thermoplastic composite material with
satisfying mechanical properties such as high stiffness and a
young modulus of at least 15 GPa.
5
[017] Another objective of the present invention is to have a
structural part comprising a thermoplastic composite material with
a satisfying W resistance.
10 [018] The further objective of the present invention is to have a
structural part comprising a thermoplastic composite material that
can be transformed and shaped into form due to a certain
flexibility.
15 [019] Still another objective of the present invention is to wet
completely, correctly and in a homogenous way the fibrous
substrate during impregnation. Any defects of fiber wetting for
example by bubbles and voids decrease the mechanical performance
of the structural part.
2 0
[020] Another objective of the present invention is the recycling
of the structural part including the composite material or
structural parts that do not meet quality standards or worn-out
structural parts. Under recycling 1s understood to recover at
25 least a part of the used raw materials. This means grinding and
reusing the thermoplastic polymer. This means also for example
that the monomer from the thermoplastic matrix of the composite
material can be recovered.
30 [021] Another objective of the present invention is to provide a
process which can be carried out at low cost and is capable of
large-scale manufacturing, to produce the structural parts
comprising the thermoplastic composite material of the invention.
In addition, the process should be easy and simple to carry out
35 using commercially available components. Also the manufacturing of
parts should be reproducible and fast meaning short cycle times.
[BACKGROUND OF THE INVENTION ]Prior art
[022]The document FR1374046 describes a process of polymerization
of acrylic monomers especially methacrylic monomers from monomer-
5 polymer syrups using a metal catalyst based on tin. Glass fibres
are impregnated with a methanol solution of the tin calatyst.
Afterwards the fibres are impregnated with a monomer-polymer syrup
and then the composition is polymerized. The process uses a metal
catalyst and the impregnation and polymerization are not made in a
10 closed mold or the same closed mold.
[023] The document JP9085841 describes the preparation of a fabric
base composite thermoplastic plastic member. A thermoplastic
polymer is dissolved in a volatile solvent and mixed with the
15 fabric base material. The solvent is evaporated and the prepreg is
cut into shapes, then it is coated again with the solution of
thermoplastic polymer in a solvent and cured by evaporation of the
solvent. In the example a polymethylmethacrylate as thermoplastic
polymer is dissolved at 15wt't; in a solvent mixture consisting of
20 methanol, xylene, tetrahydrofyran in order to impregnate the
fibrous material. This preparation method uses a lot of solvent
that evaporates.
[024] The document EP0796873 discloses a (meth) acrylic syrup, a
25 process for for preparing the syrup and a process for preparing
molding material containing the (meth)acrylic syrup. The main
objective is having a syrup with excellent storage stability. The
molding material might include a reinforcing material in form of
fibres. However the mixing of the reinforcing material and the syrup
30 is not made by impregnation process in a closed mold.
[025] In the prior no impregnation process for impregnating a
fibrous substrate is described where the fibrous substrate and the
liquid (meth) acrylic syrup are brought into contact before the
35 polymerization according to the present invention.
[026] In the prior no manufacturing process for manufacturing
mechanical or structured parts or articles is described including the
impregnation process for impregnating a fibrous substrate with a
liquid (meth) acrylic syrup and polymerization according to the
5 present invention.
[Brief description of the invention]
[027]Surprisingly it has been found that an impregnation process
for impregnating a fibrous substrate, wherein said fibrous
substrate is made of long fibres and said process comprises a step
of impregnating said fibrous substrate with a liquid (meth)
acrylic syrup comprising:
a) a (meth) acrylic polymer,
b) a (meth) acrylic monomer,
c) at least one initiator or initiating system for
starting the polymerization of the (meth) acrylic monomer,
said liquid (meth)acrylic syrup has a dynamic viscosity of a value
In the range from 10 mPa*s to 10000 mPaxs, preferably from 50
mPa*s to 5000 rnPaXs and advantageously from 100 mPa*s to 1000
mPa*s yields to a complete and correct impregnation of the fibrous
substrate.
[028]Surprisingly it has also been discovered that an impregnation
liquld (meth) acrylic syrup for implementing the impregnation
25 process for a fibrous substrate, said liquid (meth) acrylic syrup
comprises:
a) a (meth) acrylic polymer,
b) a (meth) acrylic monomer,
c) at least one initiator or initiating system for
starting the polymerization of the (meth) acrylic
monomer,
said liquid (meth)acrylic syrup has a dynamic viscosity of a value
in the range from 10 mPa*s to 10000 mPa*s, preferably from 50
mPa*s to 5000 mPa*s and advantageously from 100 mPa*s to 1000
35 mPa*s yields to a complete and correct impregnation of the fibrous
substrate.
[029] Surprisingly it has also been discovered that a manufacturing
process for manufacturing mechanical or structured parts or articles
comprising following steps:
a) impregnating a fibrous substrate with a liquid (meth)
acrylic syrup,
b) polymerising the liquid (meth) acrylic syrup impregnating
said fibrous substrate
yields to manufactured mechanical or structured parts or articles having
satisfying mechanical properties by possessing a high stiffness
and a young modulus of at least 15 GPa.
[030]Additionally it has also been discovered that a threedimensional
mechanical or structured parts obtained by the
manufacturing process possessing a high stiffness and a young
15 modulus of at least 15 GPa, has nearly no defects as voids between
the fibrous substrate and the (meth)acrylic polymer.
[Detailed description o f the invention]
[031] According to a first aspect, the present invention relates to
20 an impregnation process for impregnating a fibrous substrate,
wherein said fibrous substrate is made of long fibres and said
process comprises a step of impregnating said fibrous substrate
with a liquid (meth) acrylic syrup comprising:
a) a (meth) acrylic polymer,
b) a (meth)acrylic monomer,
c) at least one initiator or initiating system for
starting the polymerization of the (meth) acrylic monomer,
said liquid (meth)acrylic syrup has a dynamic viscosity of a value
in the range from 10 mPa*s to 1OOOO mPaxs, preferably from 50
30 mPa*s to 5000 mPa*s and advantageously from 100 mPa*s to 1000
mPa* s .
[032] According to another aspect the impregnation process of the
fibrous substrate of the present invention is made in a closed
35 mold.
[033]According to still another aspect the impregnation process of
the fibrous substrate of the present invention is made with a
liquid (meth) acrylic syrup that comprises a (meth)acrylic polymer
which is a homo- or copolymer of methyl methacrylate (MMA) or a
5 mixture thereof.
[034]By the term "fibrous substrate" as used are denoted fabrics,
felts or nonwovens that may be in the form of strips, laps,
braids, locks or pieces.
10 [035] By the term "(meth)acrylic" as used is denoted all kind of
acrylic and methacrylic monomers.
[036] By the term "PMMA" as used are denoted homo- and copolymers
of methylmethacrylate (MMA), for the copolymer of MMA the weight
ratio of MMA inslde the PMMA is at least 70 wt%.
15 [037] By the term "monomer" as used is denoted is a molecule which
can under go polymerization.
[038] By the term "polymerization" as used is denoted the process
of converting a monomer or a mixture of monomers into a polymer.
[039] By the term "thermoplastic polymer" as used is denoted a
20 polymer that turns to a liquid or becomes more liquid or less
viscous when heated and that can take on new shapes by the
application of heat and pressure.
[040]By the term "thermosetting polymer" as used is denoted a
prepolymer in a soft, solid or viscous state that changes
25 irreversibly into an infusible, insoluble polymer network by
curing.
[041]By the term "polymer composite" as used is denoted a
multicomponent material comprising multiple different phase
domains in which at least one type of phase domain is a continuous
30 phase and in which at least one component is a polymer.
[042]Ey the term "initiator" as used is denoted a chemical species
that's reacts with a monomer to form an intermediate compound
capable of linking successively with a large number of other
rnonorners into a polymeric cornpound.
3 5
[043]With regard to structured part or article this concerns a
panel, a cover or a hull made of composite material or parts for
aircrafts, for boats (hull and deck), rail cars (hatch, partition,
body), and automotive parts (car body, hood, door. )
5
[044]With regard to the (metha)acrylic polymer, one could mention
poly alkyl methacrylates or poly alkyl acrylates. In a preferred
embodiment the (meth)acrylic polymer is poly methyl methacrylate
(PMMA) .
10 [045] The term "PMMA" denotes a methyl methacrylate (MMA)
homopolymer or a copolymer or mixtures thereof.
[046]In one embodiment the homo- or copolymer of methyl
methacrylate (MMA) comprises at least 70%, preferably at least
80%, advantageously at least 90% and more advantageously at least
15 95% by weight of methyl methacrylate.
[047] In another embodiment the PMMA is a mixture of at least one
homopolymer and at least one copolymer of MMA, or a mixture of at
least two homopolymers or two copolymers of MMA with a different
average molecular weight or a mixture of at least two copolymers
20 of MMA with a different monomer composition.
[048] The copolymer of methyl methacrylate (MMA) comprises from 70%
to 99.7% by weight of methyl methacrylate and from 0.3 to 30% by
weight of at least one monomer having at least one ethylenic
unsaturation that can copolymerize with methyl methacrylate.
25 [049]These monomers are well known and mention may be made, in
particular of acrylic and methacrylic aclds and alkyl-
(meth)acrylates In which the alkyl group has from 1 to 12 carbon
atoms. As examples, mention may be made of methyl acrylate and
ethyl., butyl or 2-ethylhexyl (meth)acrylate. Preferably the
30 comonomer is an alkyl acrylate in which the alkyl group has from 1
to 4 carbon atoms.
[050] In a preferred embodiment the copolymer of methyl
methacrylate (MMA) comprises from 708 to 99.7%, preferably from
809 to 99.72 advantageously from 90% to 99.7% and more
35 advantageously from 90% to 99.5% by weight of methyl methacrylate
and from 0.3% to 30%, preferably from 0.3% to 20% advantageously
from 0.3% to 108 and more advantageously from 0.5% to 10% by
weight of at least one monomer having at least one ethylenic
unsaturation that can copolymerize with methyl methacrylate.
Preferably the comonomer is chosen from methyl acrylate or ethyl
acrylate or mixtures thereof.
5 [051] The weight average molecular weight of the (meth) acrylic
polymer should be high, meaning larger than 50 000g/mol,
preferably larger than 100 000g/mol.
[052] The weight average molecular weight can be measured by size
exclusion chromatography (SEC).
10
[053] With regard to the (meth) acrylic monomer, the monomer is
chosen from acrylic acid, methacrylic acid, alkyl acrylic
monomers, alkyl methacrylic monomers and mixtures thereof.
[054] Preferably the monomer is chosen from acrylic acid,
15 methacrylic acid , alkyl acrylic monomers, alkyl methacrylic
monomers and mixtures thereof, the alkyl group having from 1 to 22
carbons, either linear, branched or cyclic; preferably the alkyl
group having from 1 to 12 carbons, either linear, branched or
cyclic.
20 [055]Advantageously the meth)acrylic monomer is chosen from methyl
methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate,
methacrylic acid, acrylic acid, n-butyl acrylate, iso-butyl
acrylate, n- butyl methacrylate, iso-butyl methacrylate,
cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate,
25 isobornyl methacrylate and mixtures thereof.
[056]More advantageously the monomer is chosen (meth)acrylic
monomer is chosen from methyl methacrylate, isobornyl acrylate or
acrylic acid and mixtures thereof.
[057]In a preferred embodiment at least 50wt%, preferably at least
30 60wt% of the monomer is methyl methacrylate.
[058] In a more preferred embodiment at least 50wt%, preferably at
least 6Owt%, more preferably at least 70wt% and advantageously at
least 80wt% and even more advantageously 90wtB of the monomer is a
mixture of methyl methacrylate with isobornyl acrylate and/or
35 acrylic acid.
[059]With regard to the f i b r o u s s u b s t r a t e , one can mentlon
f a b r i c s , f e l t s or nonwovens t h a t may be i n t h e form of s t r i p s ,
l a p s , b r a i d s , locks or p i e c e s . The f i b r o u s m a t e r i a l can have
d i f f e r e n t forms and dimensions e i t h e r one dimensional, two
5 dimensional o r t h r e e dimensional. A f i b r o u s s u b s t r a t e comprises an
assembly of one o r more f i b r e s . When t h e f i b r e s a r e continuous,
t h e i r assembly forms f a b r i c s .
[060] The one dimensional form is l i n e a r long f i b r e s . The f i b e r s
may be discontinuous or continuous. The f i b e r s may be arranged
10 randomly o r a s a continuous f i l a m e n t p a r a l l e l t o each o t h e r . A
f i b e r i s defined by l t s aspect r a t i o , which is t h e r a t i o between
l e n g t h and diameter of t h e f i b e r . The f i b e r s used i n t h e p r e s e n t
invention a r e long f i b e r s o r continuous f i b e r s . The f i b e r s have an
a s p e c t r a t i o of a t l e a s t 1000, p r e f e r a b l y a t l e a s t 1500, more
15 p r e f e r a b l y a t l e a s t 2000, advantageously at l e a s t 3000 and most
advantageously a t l e a s t 5000.
[061] The two dimensional form a r e f i b r o u s mats o r non woven
reinforcements or woven roving o r bundles of f i b e r s , whlch can
a l s o be braded.
20 [062] The t h r e e dimensional form a r e f o r example s t a c k e d o r folded
f i b r o u s mats or non woven reinforcements o r bundles of f i b e r s o r
mixtures t h e r e o f , an assembly of t h e two dimensional form i n t h e
t h i r d dimension.
[063] The o r i g i n s of the fibrous m a t e r i a l can be a n a t u r a l o r a
25 s y n t h e t i c one. As n a t u r a l m a t e r i a l one can mention vegetable
f i b e r s , wood f i b e r s , animal f i b e r s o r mineral f i b e r s .
[O64] Natural f i b e r s a r e f o r example s i s a l , j u t e , hemp, f l a x ,
c o t t o n , coconut f i b e r s , and banana f i b e r s . Animal f i b e r s a r e f o r
example wool or h a l r .
30 [065]As synthetic material one can mention polymeric f i b e r s chosen
from f i b e r s of thermosetting polymers, from t h e r m o p l a s t i c polymers
or t h e i r mixtures.
[066] The polymeric f i b e r s can be made of polyamide ( a l i p h a t i c o r
aromatic}, p o l y e s t e r , polyvinylacohol, p o l y o l e f i n s , p o l y u r e t h a n e s ,
35 p o l y v i n y l c h l o r i d e , polyethylene, unsatured p o l y s t e r s , epoxy r e s i n s
and v i n y l e s t e r s .
[067] The mineral f i b e r s can a l s o be chosen from g l a s s f i b e r s
e s p e c i a l l y of type E, R o r 52, carbon f i b e r s , boron f i b e r s o r
s i l i c a f i b e r s .
[068]The f i b r o u s s u b s t r a t e of t h e p r e s e n t i n v e n t i o n is chosen from
5 vegetable f i b e r s , wood f i b e r s , animal f i b e r s , mineral f i b e r s ,
s y n t h e t i c polymeric f i b e r s , g l a s s f i b e r s , carbon f i b e r s o r
mixtures t h e r e o f .
[069] Preferably the f i b r o u s s u b s t r a t e is chosen from mineral
f i b e r s .
[070]With regard t o the i n i t i a t o r o r i n i t i a t i n g system f o r
s t a r t i n g t h e polymerization of t h e (meth) a c r y l i c monomer, one
could mention i n i t i a t o r s or i n i t i a t i n g systems t h a t a r e a c t i v a t e d
by heat.
15 [071] The heat a c t i v a t e d i n i t i a t o r i s p r e f e r a b l y a r a d i c a l
i n i t i a t o r .
[072]With regard t o t h e radical i n i t i a t o r , t h e y can be chosen from
d i a c y l peroxides, peroxy e s t e r s , d l a l k y l p e r o x i d e s , p e r o x y a c e t a l s
o r azo compounds.
20 [073] The i n i t i a t o r o r i n i t i a t i n g system f o r s t a r t i n g t h e
polymerization o f the (meth) a c r y l i c monomer is chosen from
isopropyl carbonate, benzoyl peroxide, l a u r o y l peroxide, caproyl
peroxide, dicumyl peroxide, t e r t - b u t y l perbenzoate, t e r t - b u t y l
per (2-ethylhexanoate), cumyl hydroperoxide, 1 , l - d i (tert-
25 butylperoxy) -3,3,5-trimethylcyclohexane, t e r t - b u t y l
peroxyisobutyrate, t e r t - b u t y l p e r a c e t a t e , t e r t - b u t y l p e r p i v a l a t e ,
amyl p e r p i v a l a t e , t e r t - b u t y l p e r o c t o a t e , a z o b i s l s o b u t y r o n i t r i l e
(AIBN) r a z o b ~ s i s o b u t y r a m i d e , 2 , Z r - a z o b i s (2,4-
d i m e t h y l v a l e r o n i t r i l e ) o r 4,4'-azobis(4-cyanopentanoic) . It would
30 not be d e p a r t i n g from t h e scope of t h e i n v e n t i o n t o use a mixture
of r a d i c a l initiators chosen from t h e above l i s t .
[074] Preferably the i n i t i a t o r or I n i t i a t i n g system f o r s t a r t i n g
t h e polymerization of t h e (meth) a c r y l i c monomer i s chosen from
peroxides having 2 t o 20 carbon atoms
35 [075] The content of r a d i c a l i n i t i a t o r w i t h r e s p e c t t o t h e
( m e t h ) a c r y l i c monomer of t h e a l i q u i d (meth) a c r y l i c syrup i s from
100 to 50000 ppm by weight (50000ppm=5wt4), p r e f e r a b l y between 200
and 40000 ppm by weight and advantageously between 300 and 30000
PP" -
[076] The (meth)acrylic monomer is typically one or more monomers
5 as defined above with, optionally, a suitable inhibitor such as
hydroquinone (HQ) , methyl hydroquinone (MEHQ) , 2,6-di-tertiarybutyl-
4-methoxyphenol (Topanol 0) and 2,4-dimethyl-6-tertiarybutyl
phenol (Topanol A) .
[077] The inhibitor is present to prevent the monomer from
10 spontaneously polymerising.
10781 The liquid (meth) acrylic syrup comprises optionally also an
activator for the polymerization.
[079] Polymerisation activator or accelerator is chosen from
tertiary amines such as N, N-dimethyl-p-toluidine (DMPT) , N, N-
15 dihydroxyethyl-p-toluidine (DHEPT), organic-soluble transition
metal catalysts or mixtures thereof.
[080]Advantageously the liquid (meth) acrylic syrup contains no
metal based catalysts. No metal comprising additives as activators
for catalytically accelerate the polymerization reaction are added
20 to liquid (meth) acrylic syrup the liquid (meth) acrylic syrup
according to the invention. These concerns especially tin based
compounds as tin chloride.
[081] The content of the activator with respect to the to the
25 (meth)acrylic monomer of the liquid (meth) acrylic syrup is from
100ppm to 10000 ppm (by weight), preferably from 200ppm to
7000 ppm by weight and advantageously from 300ppm to 4000 ppm.
[082] The presence of activators or accelerators depends upon the
30 final application. Where "cold-cure" is necessary or wished, an
accelerator is usually necessary. Cold cure means that the
polymerization takes place at ambient temperature, meaning less
than 50°C or preferably less than 40'~.
35 [083] However, for industrial applications the use of heat in
"heat-cure" systems is also possible.
10841 Another ingredient in the liquid resin can also be a chainlimiting
agent in order to control the molecular weight, for
example y-terpinene or terpinolene, at contents of between 0 and
500 ppm and preferably between 0 and 100 ppm, with respect to the
5 monomers of the mixture.
[085]The impregnation process according to the invention for
impregnating a fibrous substrate comprises a step of impregnating
the fibrous substrate with a liquid (meth)acrylic syrup.
10 10861 A simple (meth) acrylic monomer or a (meth) acrylic monomer
mixture as liquid (meth)acrylic syrup is too liquid for the
impregnation process of the present invention, especially for the
correct and complete wetting and impregnation of the fibrous
substrate. Therefore the viscosity has to be adapted by increasing
15 it.
10871 With regard to the liquid (meth) acrylic syrup according to
the invention that impregnates the fibrous substrate, it comprises
a (meth)acrylic monomer or a mixture of a (meth)acrylic monomers,
20 a (meth)acrylic polymer and at least one initiator or initiating
system for starting the polymerization of the (rneth) acrylic
monomer.
[088]According to the invention the viscosity is increased by
using (meth)acrylic monomer or a mixture of a (meth)acrylic
25 monomers with dissolved (meth) acrylic polymer or (meth) acrylic
polymers. This solution is commonly referred to as "syrup" or
"prepolymer" .
[089]Advantageously the liquid (meth) acrylic syrup contains no
additionally voluntary added solvent.
30 [090]The (rneth)acrylic polymer is completely soluble in the
(meth)acrylic monomer.
[091] This (meth)acrylic polymer is PMMA, meaning the homo- or
copolymer of methyl methacrylate (MMA) or a mixture thereof as
defined before.
35 [092]This (meth)acrylic monomer is the same as defined before.
10931 The (meth) acrylic monomer or the (meth) acrylic monomers in
the liquid (meth) acrylic syrup present at least 40% by weight,
preferably 50% by weight, advantageously 60-y weight and more
advantageously 65% by weight of total liquid (meth) acrylic syrup
5 in view of (meth) acrylic monomer and (meth) acrylic polymer.
[OW] The (meth)a crylic monomer or the (meth)a crylic monomers in
the liquid (meth) acrylic syrup present at most 90% by weight,
preferably at most 85% by weight, advantageously at most 82% by
weight and more advantageously at most 80% by weight of total
10 liquid syrup in view of (meth)acrylic monomer and (meth)acrylic
polymer.
[095]The (meth)acrylic polymer or polymers in the liquid (meth)
acrylic syrup present at least 104 by weight, preferable at least
15%, advantageously at least 18% and more advantageously at least
15 20% by weight of total liquid (meth) acrylic syrup in view of
(meth) acrylic monomer and (meth) acrylic polymer.
[096] The (meth)acrylic polymer or polymers in the liquid (meth)
acrylic syrup present at most 60% by weight, preferable at most
50%, advantageously at most 40% and more advantageously at most
20 35% by weight of total liquid (meth) acrylic syrup.
[097] The (meth) acrylic monomer or the (meth) acrylic monomers in
the liquid (meth) acrylic syrup presents from 40% to 90% by
weight, preferably from 50% to 90% by weight, advantageously from
55% to 85% by weight and more advantageously from 60% to 80% by
25 weight of total liquid syrup in view of (meth)acrylic monomer and
(meth) acrylic polymer.
[098] Accordingly (meth) acrylic polymer or polymers in the liquid
(meth) acrylic syrup presents from 60% to 10% by weight,
preferably from 50% to 103, by weight, advantageously from 15% to
30 45% by weight and more advantageously from 20% to 40% by weight of
total liquid syrup in view of (meth)acrylic monomer and
(meth)acrylic polymer.
[099] The dynamic viscosity of the liquid (meth) acrylic syrup is
in a range from 10 mPa*s to 10000 mPa*s, preferably from 50 mPa*s
35 to 5000 mPa*s and advantageously from 100 mPa*s to 1000 mPa*s. The
viscosity of the syrup can be easily measured with a Rheometer or
viscosimeter. The dynamic viscosity is measured at 25OC. The
liquid (meth) acrylic syrup has a Newtonian behaviour, meaning no
shear thinning, so that the dynamic viscosity is independent of
the shearing in a rheometer or the speed of the mobile in a
viscosimeter.
5 [loo] If the viscosity of the liquid (meth) acrylic syrup at a
given temperature is too high for the impregnation process and for
the correct impregnation, it is possible to heat the syrup in
order to have a more liquid syrup within the before mentioned
dynamic viscosity interval at the respective temperature during
10 which the impregnation takes place for the sufficient wetting and
correct and complete impregnation of the fibrous substrate.
[loll The liquid syrup according to the present invention does not
contain any additional solvent voluntary added.
15 [I021 The liquid (meth) acrylic syrup may comprise also other
additives and fillers. A filler in the scope of the present
invention is not considered as an additive.
[103]All the additives and fillers can be added to the liquid
(meth) acrylic syrup before the impregnation.
20 [I041 As additives one can mention organic additives as impact
modifiers or block copolymers, thermal stabilizers, UV
stabilizers, lubricants and mixtures thereof.
[lo51 The impact modifier is in the form of fine particles having
an elastomeric core and at least one thermoplastic shell, the size
25 of the particles being in general less than 1 pm and
advantageously between 50 and 300 nm. The impact modifier is
prepared by emulsion polymerization. The impact modifier content
in the liquid (meth) acrylic syrup 1s from 0 to 50wt%, preferably
from 0 to 25wt?, and advantageously from 0 to 20% by weight.
30 [lo61 4s flllers one can mention carbon nanotubes or mineral
charges including mineral nano charges (Ti02, silica).
[107]The f~ller content in the liquid (meth) acrylic syrup is from
0 to 20 wt8.
35 [108]An additional aspect according to the present invention is
the impregnation process, for impregnating a fibrous substrate,
wherein said fibrous substrate is made of long fibres and said
process comprises a step of impregnating said fibrous substrate
with a liquid (meth) acrylic syrup comprising:
a) from 10wtg to 59.99wtg (meth)a crylic polymer,
b) from 40wt% to 89.99wtg (meth) acrylic monomer,
c) from O.Olwt% to 5wt% one initiator or initiating
system for starting the polymerization of the
(meth) acrylic monomer,
d) from Owt% to lwt% activator,
e) from Owtk to 20wt% filler,
10 f) from Owt to 20wtS additives.
[log] Another additional aspect according to the present invention
is the impregnation liquid (meth) acrylic syrup for implementing
the impregnation process according to any of the preceding claims,
15 said liquid (meth) acrylic syrup comprises
a) a (meth) acrylic polymer,
b) a (meth) acrylic monomer,
C) at least one initiator or initiating system for
starting the polymerization of the (meth)
2 0 acrylic monomer,
said liquid (meth)acrylic syrup has a dynamic viscosity of a value
in the range from 10 mPa*s to 10000 mPa*s, preferably from 50
mPa*s to 5000 mPa*s and advantageously from 100 mPa*s to 1000
mPa* s .
2 5
[110]Still another additional aspect according to the present
invention is an impregnation liquid (rneth) acrylic syrup
comprising:
from lOwtB to 59.99wt% (meth)acrylic polymer,
3 0 from 40wt% to 89.99wtB(meth)acryllc monomer,
from O.Olwt% to 5wth one initiator or initiating
system for starting the polymerization of the
(meth) acrylic monomer,
from Owt% to lwt% activator,
from Owt% to 20wt5 fillers,
from Owt to 20wt% additives.
[Ill] Still another aspect of the present invention is a
manufacturing process for manufacturing mechanical or structured parts
or articles comprising following steps:
a) impregnating a fibrous substrate with a liquid (meth)
acrylic syrup,
b) polymerising the liquid (meth) acrylic syrup
impregnating said fibrous substrate.
[I121 Preferably the impregnation of the fibrous substrate in step
a) is made in a closed mold.
10 [I131 Advantageously the step a) and step b) are made in the same
closed mould.
[114]The mold is opaque towards visible and ultraviolet radiation
at least on one side
[I151 closed mold will amongst other things avoid and reduce the
15 evaporation of the monomer and protect the environment.
[I161 Using the same closed mold will avoid the transfer of the
material after impregnation and polymerizing in a closed mold will
guarantee a good distribution of the heat, having a satisfying
yield of polymerization and eventually evaporation of the
20 monomer (s) .
[I171 No metals are present in manufactured mechanical or structured
parts or articles such as tin are present corning from accelerators
added for the polymerization step.
25 [I181 The manufactured mechanical or structured parts or articles do not
contain any additional solvent voluntary added, since the syrup
did not contain any additional solvent for the impregnation step.
[I191 With regard to the manufactured mechanical or structured parts or
30 artlcles of the present invention, it comprises at least 20% by
weight of fibrous substrate, preferable at least 40% by weight of
fibrous material advantageously at least 50% by weight of fibrous
material and advantageously at least 55% by weight of fibrous
material based on the total composition.
35 [I201 The manufactured mechanical or structured parts or articles of the
present lnventlon, it comprises at most 99% by weight of fibrous
material, preferable at most 95% by weight of fibrous material
advantageously a t most 904 by weight of f i b r o u s m a t e r i a l and
advantageously a t most 806 by weight of f i b r o u s m a t e r i a l based on
t h e t o t a l composition.
5 [I211 Due to the manufacturing process f o r manufacturing mechanical or
structured parts or a r t l c l e s according to the invention a complete,
c o r r e c t and homogenous w e t t i n g o f t h e f i b r o u s s u b s t r a t e during
impregnation takes place. There a r e no d e f e c t s of f i b e r w e t t i n g
during impregnation f o r example by bubbles and voids t h a t decrease
10 t h e mechanical performance of the manufacturing mechanical or
structured parts or a r t i c l e s .
[I221 The manufactured mechanical or s t r u c t u r e d p a r t s o r a r t i c l e s
according t o t h e invention do n o t comprise e s s e n t i a l l y any p o r e s .
By pore is meant a s p h e r i c a l void with a diameter of a t l e a s t 1pm
15 o r l a r g e r o r an elongated e l l i p s o i d a l v o i d i n form of an o b l a t e
with a s m a l l e s t p r i n c i p a l axe of a t least 0.5pm or l a r g e r . By
"comprising e s s e n t i a l l y no pores" is meant t h a t t h e pores
r e p r e s e n t l e s s then 1 vol%, p r e f e r a b l y less then 0 . 5 ~ 0 1 %a nd more
p r e f e r a b l y l e s s then 0 . 2 ~ 0 1 % of t h e t o t a l volume of t h e
20 manufactured mechanical or structured parts or a r t i c l e s .
[123]With regard t o manufacturing p r o c e s s f o r manufacturing
mechanical or structured parts or a r t i c l e s comprising t h e polymeric
composite m a t e r i a l , s e v e r a l methods could be used i n order t o
25 p r e p a r e three-dimensional mechanical or s t r u c t u r e d p a r t s . One can
mention i n f u s i o n , vacuum bag moulding, p r e s s u r e bag molding,
autoclave molding, r e s i n t r a n s f e r moulding (RTM), r e a c t i o n
i n j e c t i o n molding (RIM) r e i n f o r c e d r e a c t i o n i n j e c t i o n molding (RRIM)
and v a r i a n t s t h e r e o f , press molding o r compression molding.
3 0
[I241 The p r e f e r r e d manufacturing p r o c e s s f o r manufacturing
mechanical or structured parts or a r t i c l e s comprising t h e composite
m a t e r i a l s a r e processes were t h e l i q u i d (meth) a c r y l i c syrup
t r a n s f e r r e d t o the f i b r o u s s u b s t r a t e by impregnating t h e f i b r o u s
35 s u b s t r a t e i n a mold more p r e f e r a b l y i n a c l o s e d mold.
[I251 Advantageously the impregnation s t e p of t h e f i b r o u s m a t e r i a l
is made i n a closed mold.
[126]Most advantageously the manufacturing process for
manufacturing mechanical or structured parts or articles comprising the
polymeric composite material is chosen from resin transfer molding
or infusion.
5
[I271 All processes comprise the step of impregnating the fibrous
substrate with the liquid (meth) acrylic syrup before the
polymerization step in a mold.
[I281 The step of polymerising of the liquid (meth) acrylic syrup
10 impregnating said fibrous substrate takes place after the
impregnation step in the same mold.
[129]Resin transfer molding is a method using a two sided mold set
which forms both surfaces of composite material. The lower side is
15 a rigid mould. The upper side can be a rigid or flexible mould.
Flexible moulds can be made from composite materials, silicone or
extruded polymer films such as nylon. The two sides fit together
to produce a mould cavity. The distinguishing feature of resin
transfer moulding is that the fibrous substrate is placed into
20 this cavity and the mould set is closed prior to the introduction
of the liquid (meth) acrylic syrup. Resin transfer moulding
includes numerous varieties which differ in the mechanics of how
the liquid (meth) acrylic syrup is introduced to the fibrous
substrate in the mould cavity. These variations include everything
25 from vacuum infusion to vacuum assisted resin transfer moulding
(VARTM). This process can be performed at either ambient or
elevated temperature. Ambient temperature means between 10°C and
50°C. Elevated temperature means up to 200°C. Preferably elevated
temperature 1s from 50°C up to 160°C.
3 0
[I301 With the infusion method the liquid (meth) acrylic syrup does
have to have the adapted viscosity towards this preparation method
of the polymeric composite material. The liquid (meth) acrylic
syrup is aspired into the fibrous substrate present in a special
35 mold by application of a slight vacuum. The fibrous substrate is
infused and completely impregnated by the liquid (meth) acrylic
syrup.
[I311 One advantage of this method is the high amount of fibrous
material in the composite.
[I321 With regard to the use of manufactured mechanical or structured
parts or articles, one can mention automotive applications, nautical
applications, railroad applications, sport, aeronautic and
aerospace applications, photovoltaic applications, computer
related applications, telecommunication applications and wind
energy applications.
[I331 Particularly the three-dimensional mechanical or structured
part is a automobile part, boat part, train part, sport article,
plane or helicopter part, space ship or rocket part, photovoltaic
module part, wind turbine part, furniture part, construction or
building part, telephone or cell phone part, computer or
television part, printer and photocopy part.
[134]With regard to the recycling of the structured part,
comprising the thermoplastic composite material it can be made by
grinding or depolymerization of the thermoplastic polymer.
[I351 Grinding is made mechanically in order to obtain smaller
parts of pieces. As the structured part compromises thermoplastic
polymer, this polymer can be heated, and the pieces again
transformed in a certain limit in order to obtain a recycled
object.
[136]Preferably the structured part comprising the thermoplastic
composite is heated for making a pyrolysis or thermal
decomposition of the PMMA and recovering the methyl methacrylate
as monomer.
[137]Advantageously at least 50 w t h f the MMA present in the
polymer are recovered by thermal decomposition.
[I381 The structured part is heated at a temperature of at least
200°C and no more than 400°C.
(1391 So, a final subject of the present invention relates to the
use of the impregnation process or of the manufacturing process
according to the invention, particularly when the said methacrylic
polymer is an homopolymer or/and a copolymer of methyl
rnethacrylate, i n t h e manufacture of mechanical and/or s t r u c t u r a l
p a r t s which a r e r e c y c l a b l e by t h e r m a l depolymerisation (by means
of p y r o l y s i s ) , p r e f e r a b l y with a t l e a s t 50% of the monomers,
p a r t i c u l a r l y o f methyl rnethacrylate (MMA)recovered.
5
[Examples]
[140]Example 1: A syrup is prepared by d i s s o l v i n g 25 p a r t s by
weight of t h e PMMA (BS520 a copolymer of MMA comprising e t h y l
a c r y l a t e a s a comonomer) i n 75 p a r t s by weight of methyl
10 m e t h a c r y l a t e , which is s t a b i l i z e d with MEHQ (hydroquinone
monomethyl e t h e r ) . To t h e 100 p a r t s by weight of t h e syrup a r e
added 2 p a r t s by weight of benzoyl peroxide (BPO - Luperox A75
from ARKEMA) and 0.2 p a r t s by weight o f DMPT (N,N-dimethyl-pt
o l u i d i n e from Sigma-Aldrich). The syrup has a dynamic v i s c o s i t y of
15 520 mPaks a t 2 5 ° C . The syrup is i n j e c t e d i n a closed mould
comprising a g l a s s f a b r i c a s f i b r o u s s u b s t r a t e and polymerized a t
2 5 ' ~ during 80 minutes.
[I411 A s t r u c t u r a l p a r t i n form of a s h e e t i s obtained from t h e
mould.
20 11421 The sheet has a good adherence of t h e t h e r m o p l a s t i c polymer
t o t h e f i b r o u s s u b s t r a t e .
[143]The s h e e t p o s s e s s e s a l s o s a t i s f y i n g mechanical p r o p e r t i e s .
[144]After u t i l i s a t i o n t h e s t r u c t u r a l p a r t i n form of a s h e e t can
be recycled by h e a t i n g and d e p o l y m e r i s a t i o n .
We Claim:
1. An impregnation process for impregnating a fibrous substrate,
wherein said fibrous substrate is made of long fibres and said
5 process comprises a step of impregnating said fibrous
substrate with a liquid (meth) acrylic syrup comprising:
a) a (meth)acrylic polymer,
b) a (meth) acrylic monomer,
C) at least one initiator or initiating system for
starting the polymerization of the (meth)
acrylic monomer,
said liquid (meth)acrylic syrup has a dynamic viscosity of a
value in the range from 10 mPa*s to 10000 mPa*s, preferably
from 50 mPa*s to 5000 mPa*s and advantageously from 100 mPa*s
15 to 1000 mPaxs.
2. The impregnation process according to claim 1, characterized
that the step of impregnation of said fibrous substrate is
made in a closed mold.
2 0
3. The impregnation process according to claim 1 or 2,
characterized that the (meth)acrylic polymer is a homo- or
copolymer of methyl methacrylate (MMA) or a mixture thereof.
25 4. The impregnation process according to any of claims 1 to 3,
characterized that the copolymer of methyl methacrylate (MMA)
comprises at least 709, preferably at least 802,
advantageously at least 908 and more advantageously at least
95% by weight of methyl methacrylate (MMA) .
3 0
5. The impregnation process according to any of claims 1 to 4,
characterized that the copolymer of methyl methacrylate (MMA)
comprises from 70% to 99.7% by weight, preferably from 805 to
99.7% by weight, advantageously from 90% to 99.79 by weight
3 5 and more advantageously from 90% to 99.55 by weight of methyl
methacrylate and from 0.3 to 30% by weight, preferably from
0.3% to 208 by weight, advantageously from 0.3% to 10% and
more advantageously from 0.5% t o 108 by weight of a t l e a s t one
monomer having a t l e a s t one e t h y l e n i c u n s a t u r a t i o n t h a t can
copolymerize with methyl methacrylate.
5 6. The impregnation p r o c e s s according t o any o f claims 1 t o 5,
c h a r a c t e r i z e d t h a t t h e ( m e t h ) a c r y l i c polymer comprises a
comonorner, s a i d comonomer is an a l k y l a c r y l a t e having an a l k y l
group from 1 t o 12 carbon atoms.
10 7 . The impregnation p r o c e s s according t o claim 6, c h a r a c t e r i z e d
t h a t t h e comonomer is chosen from methyl a c r y l a t e o r e t h y l
a c r y l a t e and a mixture t h e r o f .
8. The impregnation p r o c e s s according t o any of claims 1 t o 7,
c h a r a c t e r i z e d t h a t the ( m e t h ) a c r y l i c monomer is chosen from
a c r y l i c a c i d , methacrylic a c i d , a l k y l a c r y l i c monomers, a l k y l
m e t h a c r y l i c monomers and mixtures t h e r e o f , the a l k y l group
having from 1 t o 22 carbons, e i t h e r l i n e a r , branched o r
c y c l i c ; p r e f e r a b l y t h e a l k y l group having from 1 to 12
carbons, e i t h e r l i n e a r , branched o r c y c l i c .
The impregnation process according t o any o f claims 1 to 8,
c h a r a c t e r i z e d t h a t the ( m e t h l a c r y l i c monomer is chosen from
methyl m e t h a c r y l a t e , e t h y l methacrylate, methyl a c r y l a t e ,
e t h y l a c r y l a t e , methacrylic a c i d , a c r y l i c acid, n-butyl
a c r y l a t e , i s o - b u t y l a c r y l a t e , n- b u t y l m e t h a c r y l a t e , i s o - b u t y l
m e t h a c r y l a t e , cyclohexyl a c r y l a t e , cyclohexyl methacrylate,
i s o b o r n y l a c r y l a t e , isobornyl methacrylate and mixtures
t h e r e o f .
The impregnation p r o c e s s according t o any of claims 1 t o 9,
c h a r a c t e r i z e d t h a t the ( m e t h l a c r y l i c monomer is chosen from
methyl m e t h a c r y l a t e , i s o b o r n y l a c r y l a t e o r a c r y l i c acid and
mixtures t h e r e o f .
11. The impregnation process according to any of claims 1 to 10,
characterized that 50wt% of the (methlacrylic monomer is
methyl methacrylate.
5 12. The impregnation process according to any of claims 1 to 11,
characterized that initiator or initiating system for starting
the polymerization of the (meth) acrylic monomer is generating
radicals.
10 13. The impregnation process according to any of claims 1 to 12,
characterized that initiator or initiating system for starting
the polymerization of the (meth) acrylic monomer is chosen
from diacyl peroxides, peroxy esters, dialkyl peroxides,
peroxyacetals, azo compounds or mixtures therof.
15
14. The impregnation process according to any of claims 1 to 13,
characterized that initiator or initiating system for starting
the polymerization of the (meth) acrylic monomer is chosen
from isopropyl carbonate, benzoyl peroxide, lauroyl peroxide,
caproyl peroxide, dicumyl peroxide, tert-butyl perbenzoate,
tert-butyl per(2-ethylhexanoate), cumyl hydroperoxide, 1,ldi(
tert-buty1peroxy)-3,3,5-trimethylcyclohexane, tert-butyl
peroxyisobutyrate, tert-butyl peracet ate, tert-butyl
perpivalate, amyl perpivalate, tert-butyl peroctoate, azobisisobutyronitrile
(AIBN) , azobisisobutyramide, 2,2' -azobis (2,4-
dimethylvaleronitrile) or 4,4'-azobis(4-cyanopentanoic).
15. The impregnation process according to any of claims 1 to 14,
characterized that initiator or initiating system for starting
the polymerization of the (meth) acrylic monomer is chosen
from peroxides having 2 to 20 carbon atoms.
16. The impregnation process according to any of claims 1 to 15,
characterized that initiator or initiating system for starting
the polymerization of the (meth) acrylic monomer represents
from 100 to 50000 ppm by weight, preferably from 200 to
40000 ppm by weight and advantageously from 300 to 30000 ppm
with respect to the (meth)acrylic monomer.
17. The impregnation process according to any of claims 1 to 16,
5 characterized that the liquid (meth) acrylic syrup comprises
also an activator.
18. The impregnation process according to any of claims 1 to 17,
characterized that the liquid (meth) acrylic syrup comprises
also an activator, said activator is chosen from tertiary
arnines such as N, N-dimethyl-p-toluidine (DMPT) , N, Ndihydroxyethyl-
p-toluidine (DHEPT), organic-soluble transition
metal catalysts or mixtures thereof.
15 19. The impregnation process according to any of claims 1 to 18,
characterized that the liquid (meth) acrylic syrup comprises
also an activator, said activator represents from 100 to
10000 ppm (by weight), preferably between 200 and 7000 ppm by
weight and advantageously between 300 and 4000 ppm with
respect to the (meth) acrylic monomer.
20. The impregnation process according to any of claims 1 to 19,
characterized that the (meth)acrylic polymer in the liquid
(meth) acrylic syrup present at least 10% by weight,
preferable at least 158, advantageously at least 18% and more
advantageously at least 208 by weight of total liquid (meth)
acrylic syrup.
21. The impregnation process according to any of claims 1 to 20,
characterized that the (meth)acrylic polymer in the liquid
(meth) acrylic syrup present at most 60% by weight, preferable
at most 508, advantageously at most 40% and more
advantageously at most 358 by weight of total liquid (meth)
acrylic syrup.
3 5
22. The impregnation process according to any of claims 1 to 21,
characterized that the (meth)acrylic monomer in the liquid
(meth) acrylic syrup present at least 406 by weight,
preferably 50% by weight, advantageously 60% by weight and
more advantageously 65% by weight of total liquid (meth)
acrylic syrup.
5
23. The impregnation process according to any of claims 1 to 22,
characterized that the liquid (meth) acrylic syrup comprises
also a filler and/or an additive such as impact modifiers or
block copolymers, thermal stabilizers, W stabilizers, flame
10 retardants, lubricants and mixtures thereof.
24. The impregnation process according to any of claims 1 to 23,
characterized that the liquid (meth) acrylic syrup comprises:
a) from 10wt% to 59.99wt% (meth)acrylic polymer,
15 b) from 40wt% to 89.99wt% (meth) acrylic monomer,
c) from O.Olwt% to 5wt% one initiator or initiating
system for starting the polymerization of the
(meth) acrylic monomer,
d) from Owt% to lwt% activator,
e) from Owt% to 20wtt filler,
f) from Owt to 20wt% additives.
25. An impregnation liquid (meth) acrylic syrup for implementing
the impregnation process according to any of the preceding
2 5 claims, said liquid (meth) acrylic syrup comprises:
a) a (meth)a crylic polymer,
b) a (meth)a crylic monomer,
C) at least one initiator or initiating system for
starting the polymerization of the (meth)
3 0 acrylic monomer,
said liquid (meth)acrylic syrup has a dynamic viscosity of a
value in the range from 10 rnPa*s to 10000 mPa*s, preferably
from 50 mPa*s to 5000 mPa*s and advantageously from 100 mPa*s
to 1000 mPa*s.
3 5
26. An impregnation liquid (meth) acrylic syrup according to claim
25, wherein said syrup comprises:
a) from 10wt% to 59.99wt% (meth) a c r y l i c polymer,
b) from 40wt% to 89.99wt% (meth) a c r y l i c monomer,
C) from O.Olwt% t o 5wt% one i n i t i a t o r or i n i t i a t i n g
system f o r s t a r t i n g the polymerization of the
(meth) a c r y l i c monomer,
d) from Owt% t o l w t % a c t i v a t o r ,
e) from Owt% t o 20wtZ f i l l e r s ,
f ) from Owt t o 20wt% a d d i t i v e s .
10 2 7 . A manufacturing process for manufacturing mechanical o r structured
parts or articles comprising following s t e p s :
a) impregnating a fibrous s u b s t r a t e w i t h a l i q u i d (meth)
a c r y l i c syrup according t o any of claims 1 t o 24,
b)polymerising t h e l i q u i d (meth) a c r y l i c syrup
impregnating s a i d f i b r o u s s u b s t r a t e .
28. The process according t o claim 27, characterized t h a t the
impregnation of the f i b r o u s s u b s t r a t e i n s t e p a) is made i n a
closed mold.
2 0
29. The process according t o any of claims 27 t o 28, characterized
that in step a) and s t e p b) are made i n the same closed mold.
30. The process according t o any of claims 27 t o 29, characterized
2 5 t h a t the process is chosen from resin t r a n s f e r molding or
infusion.
31. The process according t o any of claims 27 t o 30, characterized
the temperature of the polymerization is s t e p b) is below
3 0 40°C.
32. Three-dimensional mechanical or s t r u c t u r e d p a r t s obtained by
the manufacturing process according t o claims 27 t o 31.
35 33. Part according to claim 32, which i s a automobile p a r t , boat
p a r t , t r a i n p a r t , s p o r t a r t i c l e , plane or h e l i c o p t e r p a r t ,
space ship or rocket p a r t , photovoltaic module p a r t , wind
turbine part, furniture part, construction or building part,
telephone or cell phone part, computer or television part,
printer and photocopy part.
5 34. Use of the impregnation process according to any one of claims
1 to 24 or of the manufacturing process according to any one
of claims 27 to 31, in the manufacture of recyclable
mechanical and/or structural parts, which are recyclable by
thermal depolymerisation, preferably with at least 50% of the
10 monomers, particularly of methyl methacrylate (MMA) recovered.