Field of the invention]
[001] The present invention relates to a liquid (meth) acrylic
syrup its method of polymerization and article obtained thereof.
[002] In particular the present invention deals with a liquid
(meth) acrylic syrup comprising an initiation system for
polymerization at low temperature.
[003] More particular present invention relates to a liquid (meth)
acrylic syrup comprising an initiation system for polymerization
at low temperature said initiating system comprises at least one
accelerator, at least one organic aldehyde, at least one peracid
and at least one liquid peroxy compound; an impregnation process
for a fibrous substrate, the liquid (meth) acrylic syrup for
implementing this process and the obtained impregnated fibrous
substrate. The impregnated fibrous substrate is suitable for
manufacturing mechanical or structured parts or articles.
[004] The present invention concerns also the process for
polymerizing a liquid (meth) acrylic syrup comprising an
initiation system for polymerization at low temperature said
initiating system comprises at least one accelerator, at least one
organic aldehyde at least one peracid and at least one liquid
peroxy compound.
[005] 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 .
[Technical problem]
[006] Molded articles can be obtained by polymerizing a liquid
resin comprising a monomer and a compound for starting or
initiating the polymerization and injecting this liquid resin in a
mold. There are initiators or initiating systems that are
activated by heat, meaning that the mold is heated for starting
the polymerization. There are also applications where "cold-cure"
is necessary or wished, an accelerator is usually added
additionally to the liquid resin. Cold cure means that the
polymerization takes place or can start at ambient temperature,
meaning less than 40°C. The mold has not necessarily to be heated,
but could be additionally heated in order to speed up the
kinetics .
[007] Once all the necessary compounds for the polymerization are
together in form of a liquid resin: the monomer, the initiator and
the accelerator; the system is active and the polymerization will
start inevitably after a certain time. This means the liquid resin
has to be used nearly immediately; it has a very limited shelf
life.
[008] Therefore the necessary compounds for the polymerization: the
monomer, the initiator and the accelerator are mixed together in
form of a liquid resin only moments just before the injection.
This is done by using 2 component injection with a mixing head
just before injection machine. The first component might comprise
the monomer and the accelerator while the second component is the
monomer mixed with the initiator. The premature start of the
polymerization is avoided.
[009] However the initiator is often a solid product. It is in form
of a powder that is used, for example benzoyl peroxide. The
benzoyl peroxide is tried to be mixed with the monomer. The
peroxide powder is not completely solubilized meaning no
homogenous solution is obtained. The non solubilized powder might
sink down, a non homogenous mixture is obtained and the quantities
of the peroxide injected are not correct or at least there is a
variation with time. Another problem of solid initiators that are
not correctly solubilized, is their accumulation in the tubing or
the blocking of the tubing by accumulated solids for the injection
of the liquid syrup. The initiator could be solved in a solvent
miscible with the liquid monomer, but the presence of a solvent is
not desirable in the mold, once the polymerization has been taken
place .
[010] The objective of the present invention is to solve the
disadvantages mentioned above.
[Oil] One objective of the present invention is to propose a liquid
(meth) acrylic resin composition for injection molding or
impregnation of a fibrous substrate that polymerizes at low
temperature in a reasonable time.
[012] Another objective of the present invention is to have liquid
(meth) acrylic resin composition for injection molding or
impregnation of a fibrous substrate that can easily prepared in a
one or two component system and mixed homogenously before the
injection or impregnation.
[013] The further objective of the present invention is to have a
liquid (meth) acrylic resin composition for injection molding or
impregnation of a fibrous substrate that does not block the tubing
before the injection or leaves solids coming from not dissolved
solids .
[014] 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.
[015] Still another 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
[BACKGROUND OF THE INVENTION ]Prior art
[016] The document FR1256929 describes an impregnation process
process with a liquid (meth) acrylic syrup and of polymerization
of acrylic monomers especially methacrylic monomers from monomerpolymer
syrups using benzoyl peroxide as initiator.
[017] The document US 3,476,723 describes a process for the
peroxide curing of a monomer-polymer syrup solution containing a
polymer of methyl methacrylate or a copolymer of methyl
methacrylate. The curing system comprises an organic peroxide, a
vanadium based accelerator and an aliphatic aldehyde.
[018] The document US 3,287,155 describes a process for
impregnating glass fiber mat with methyl methacrylate polymer. The
process includes the use a monomer-polymer syrup comprising tin
chloride and copper as accelerators and peroxides as curing
agents .
[019] The document WO2003/008463 describes a method for
polymerising vinyl monomers and/or oligomers comprising at least
one vinyl radical. Therefore the vinyl monomer is mixed with at
least one dioxygen supplying agent, at least one aldehyde and at
least one accelerator.
[Brief description of the invention]
[020] Surprisingly it has been found that a liquid (meth) acrylic
syrup comprising:
a ) a (meth) acrylic polymer,
b ) a (meth) acrylic monomer,
c ) at least one initiating system for starting the
polymerization of the (meth) acrylic monomer,
characterized that said initiating system comprises at least one
accelerator, at least one organic aldehyde and a peroxy compound
and organic peracid characterized that the peroxy compound is a
liquid at least at a temperature range between 0°C and 50°C, can
be injected correctly homogenously without agglomeration in the
injection head or blocking of the tubing, and can be used for the
impregnation of the fibrous substrate and polymerization at low
temperature .
[021] Surprisingly it has also been discovered that an impregnation
liquid (meth) acrylic syrup for implementing the impregnation
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 initiating system for starting the
polymerization of the (meth) acrylic monomer,
said initiating system comprises at least one accelerator, at
least one organic aldehyde and a peroxy compound and organic
peracid characterized that the peroxy compound is a liquid at
least at a temperature range between 0°C and 50°C;
yields to a complete and correct impregnation of the fibrous
substrate .
[022] 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 comprising a (meth) acrylic polymer, a
(meth) acrylic monomer and at least one initiating system for
starting the polymerization of the (meth) acrylic monomer,
characterized that said initiating system comprises at least
one accelerator, at least one organic aldehyde and a peroxy
compound and organic peracid characterized that the peroxy
compound is a liquid at least at a temperature range between
0°C and 50°C
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 .
[023] 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
modulus of at least 15 GPa, has nearly no defects as voids between
the fibrous substrate and the (meth) acrylic polymer.
[Detailed description of the invention]
[024] According to a first aspect, the present invention relates to
a a liquid (meth) acrylic syrup comprising:
a )a (meth) acrylic polymer,
b )a (meth) acrylic monomer,
c )at least one initiating system for starting the
polymerization of the (meth) acrylic monomer,
characterized that said initiating system comprises at least one
accelerator, at least one organic aldehyde and a peroxy compound
and organic peracid characterized that the peroxy compound is a
liquid at least at a temperature range between 0°C and 50 °C.
[025] By the term " (meth) acrylic" as used is denoted all kind of
acrylic and methacrylic monomers.
[026] By the term "PMMA" as used are denoted homo- and copolymers
of methylmethacrylate ( A ), for the copolymer of A the weight
ratio of MMA inside the PMMA is at least 70 wt%.
[027] By the term "monomer" as used is denoted is a molecule which
can under go polymerization.
[028] By the term "polymerization" as used is denoted the process
of converting a monomer or a mixture of monomers into a polymer.
[029] By the term "thermoplastic polymer" as used is denoted a
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.
[030] By 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
monomers into a polymeric compound.
[031] By the term "initiating system" as used is denoted a system
comprising several components capable of staring a polymerization.
[032] By the term "peroxy compound" as used is denoted a compound
comprising at least one group R-O-O-R.
[033] By the term "polymer composite" or "thermoplastic 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 phase and in which at least one component is a
polymer or respectively a thermoplastic polymer.
[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.
[035] 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
(P A ) .
[036] The term "PMMA" denotes a methyl methacrylate ( A )
homopolymer or a copolymer or mixtures thereof.
[037] 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
95% by weight of methyl methacrylate.
[038] 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
of MMA with a different monomer composition.
[039] 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.
[040] These monomers are well known and mention may be made, in
particular of acrylic and methacrylic acids 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
comonomer is an alkyl acrylate in which the alkyl group has from 1
to 4 carbon atoms .
[041] In a preferred embodiment the copolymer of methyl
methacrylate (MMA) comprises from 80% to 99.7% advantageously from
90% to 99.7% and more advantageously from 90% to 99.5% by weight
of methyl methacrylate and from 0.3% to 20% advantageously from
0.3% to 10% 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.
[042] The weight average molecular weight of the (meth) acrylic
polymer should be high, meaning larger than 50 OOOg/mol,
preferably larger than 100 OOOg/mol.
[043] The weight average molecular weight can be measured by size
exclusion chromatography (SEC) .
[044] 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.
[045] Preferably the monomer is chosen from acrylic acid,
methacrylic acid , alkyl acrylic monomers, alkyl methacrylic
monomers and mixtures thereof, the alkyl group having from 1 to 22
carbons, either linear, branched or cyclic; preferably the alkyl
group having from 1 to 12 carbons, either linear, branched or
cyclic .
[046] 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,
isobornyl methacrylate and mixtures thereof.
[047] More advantageously the monomer is chosen (meth) acrylic
monomer is chosen from methyl methacrylate, isobornyl acrylate or
acrylic acid and mixtures thereof.
[048] In a preferred embodiment at least 50wt%, preferably at least
60wt% of the monomer is methyl methacrylate.
[049] In a more preferred embodiment at least 50wt%, preferably at
least 60wt%, more preferably at least 70wt% and advantageously at
least 80wt% and even more advantageously 90wt% of the monomer is a
mixture of methyl methacrylate with isobornyl acrylate and/or
acrylic acid.
[050] With regard to the initiating system for starting the
polymerization of the (meth) acrylic monomer, one could mention
initiators or initiating systems that are activated at low
temperature by an accelerator. The initiator is preferably a
radical initiator for example a peroxy compound.
[051] The presence of activators or accelerators is necessary for
"cold-cure". Cold cure means that the polymerization could start
at ambient temperature, meaning less than 40 °C.
[052] The initiating system according to the invention comprises at
least one accelerator, at least one organic aldehyde, at least one
a peroxy compound and at least one organic peracid. The organic
peroxy and the organic peracid are not considered as the same
compound .
[053] The initiating system according to the invention can be mixed
with the other two compounds (the (meth) acrylic polymer and
(meth) acrylic monomer) in one or several steps.
[054] In a preferred embodiment the (meth) acrylic polymer and at
least a part (meth) acrylic monomer are mixed before adding all or
a at least a part of the compounds of the initiating system.
[055] With regard to the peroxy compound according to the
invention, it is peroxide, preferably organic peroxide. The
peroxide is liquid at least in a temperature range between 0°C and
50°C.
[056] Preferably the peroxide in the initiating system for starting
the polymerization of the (meth) acrylic monomer is chosen from
peroxides comprising from 2 to 30 carbon atoms.
[057] The initiator for initiating system for starting the
polymerization of the (meth) acrylic monomer is chosen from methyl
ethyl ketone peroxide, methyl isobutyl ketone peroxide, acetyl
acetone peroxide, cyclohexanone peroxide, 1,1-di (tertbutylperoxy)
cyclohexanone, tert-butyl peroxybenzoate, tert-butyl
peroxy-2-ethylhexanoate or mixtures therof.
[058] The (meth) acrylic monomer is typically one or more monomers
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 ) .
[059] The inhibitor is present to prevent the monomer from
spontaneously polymerising.
[060] With regard to the accelerator according to the invention, it
comprises a transition metal. The accelerator is an organicsoluble
compound comprising a transition metal.
[061] Preferably the transition metal is chosen from the 4th period
of the periodic system of elements.
[062] Advantageously the transition metal is chosen from Manganese,
Cobalt, Iron or Copper and more advantageously Manganese, Iron,
Copper or mixtures thereof.
[063] With regard to the aldehyde according to the invention, it
has the general formula R1CHO (1) :
0
I I
R H
[064] The group R l in formula (1) is an organic rest comprising
between 1 and 30 carbon atoms. Preferably R l is and hydrocarbon
comprising between 1 and 30 carbon atoms. Advantageously R l is an
aliphatic or aromatic hydrocarbon comprising between 1 and 30
carbon atoms. More advantageously R l is chosen from CI to C24
alkyl and/or C6 to CIO aryl .
[065] The alkyl group can be linear, branched, cyclic or comprise
also carbon-carbon double bonds.
[066] With regard to the peracid according to the invention, it has
the general formula R1COOOH (2) :
[067] The group R l in formula (2) is an organic rest comprising
between 1 and 30 carbon atoms. Preferably R l is and hydrocarbon
comprising between 1 and 30 carbon atoms. Advantageously R l is an
aliphatic or aromatic hydrocarbon comprising between 1 and 30
carbon atoms. More advantageously R l is chosen from CI to C24
alkyl or C6 to CIO aryl.
[068] The alkyl group can be linear, branched, cyclic or comprise
also carbon-carbon double bonds.
[069] Another ingredient in the liquid resin can also be a chainlimiting
agent in order to control the molecular weight, for
example g-terpinene or terpinolene, at contents of between 0 and
500 ppm and preferably between 0 and 100 ppm, with respect to the
monomers of the mixture.
[070] 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.
[071] 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
it.
[072] 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,
a (meth) acrylic polymer and at least the initiating system for
starting the polymerization of the (meth) acrylic monomer.
[073] Advantageously the liquid (meth) acrylic syrup contains no
metal based catalysts. A s metals are considered the metal elements
from the p-block of the periodic table of elements only (including
the groups 13 to 16 and therefore consequently excluding the
alkaline metals, earth alkaline metals and transition metals) . No
metal comprising additives as activators for catalytically
accelerate the polymerization reaction are added to liquid (meth)
acrylic syrup or are brought into contact with the liquid (meth)
acrylic syrup according to the invention. These concerns
especially tin based compounds as tin chloride.
[074] According to the invention the viscosity is increased by
using (meth) acrylic monomer or a mixture of a (meth) acrylic
monomers with dissolved (meth) acrylic polymer or (meth) acrylic
polymers. This solution is commonly referred to as "syrup" or
"prepolymer" .
[075] Advantageously the liquid (meth) acrylic syrup contains no
additionally voluntary added solvent.
[076] The (meth) acrylic polymer is completely soluble in the
(meth) acrylic monomer.
[077] This (meth) acrylic polymer is P A , meaning the homo- or
copolymer of methyl methacrylate ( A ) or a mixture thereof as
defined before.
[078] This (meth) acrylic monomer is the same as defined before.
[079] 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% by weight and more
advantageously 65% by weight of total liquid (meth) acrylic syrup.
[080] The (meth) acrylic polymer or polymers in the liquid (meth)
acrylic syrup present at least 10% by weight, preferable at least
15%, advantageously at least 18% and more advantageously at least
20% by weight of total liquid (meth) acrylic syrup.
[081] 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
35% by weight of total liquid (meth) acrylic syrup.
[082] 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
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 25°C. 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.
[083] If the viscosity of the liquid (meth) acrylic syrup at a
given temperature is too high for the impregnation process, it is
possible to heat the syrup in order to have a more liquid syrup
for the sufficient wetting and correct and complete impregnation
of the fibrous substrate.
[084] With regard to the fibrous substrate, one can mention
fabrics, felts or nonwovens that may be in the form of strips,
laps, braids, locks or pieces. The fibrous material can have
different forms and dimensions either one dimensional, two
dimensional or three dimensional. A fibrous substrate comprises an
assembly of one or more fibres. When the fibres are continuous,
their assembly forms fabrics.
[085] The one dimensional form is linear long fibres. The fibers
may be discontinuous or continuous. The fibers may be arranged
randomly or as a continuous filament parallel to each other. A
fiber is defined by its aspect ratio, which is the ratio between
length and diameter of the fiber. The fibers used in the present
invention are long fibers or continuous fibers.
[086] The fibers have an aspect ratio of at least 1000, preferably
at least 1500, more preferably at least 2000, advantageously at
least 3000, more advantageously at least 5000, even more
advantageously at least 6000, most advantageously at least 7500
and at most advantageously at least 10 000.
[087] The two dimensional form are fibrous mats or non woven
reinforcements or woven roving or bundles of fibers, which can
also be braded. Even if these two dimensional forms have a certain
thickness and therefore in principle a third dimension, they are
considered as two dimensional according to the present invention.
[088] The three dimensional form are for example stacked or folded
fibrous mats or non woven reinforcements or bundles of fibers or
mixtures thereof, an assembly of the two dimensional form in the
third dimension.
[089] The origins of the fibrous material can be a natural or a
synthetic one. A s natural material one can mention vegetable
fibers, wood fibers, animal fibers or mineral fibers.
[090] Natural fibers are for example sisal, jute, hemp, flax,
cotton, coconut fibers, and banana fibers. Animal fibers are for
example wool or hair.
[091] A s synthetic material one can mention polymeric fibers chosen
from fibers of thermosetting polymers, from thermoplastic polymers
or their mixtures.
[092] The polymeric fibers can be made of polyamide (aliphatic or
aromatic) , polyester, polyvinylacohol , polyolefins, polyurethanes ,
polyvinylchloride, polyethylene, unsatured polysters, epoxy resins
and vinylesters .
[093] The mineral fibers can also be chosen from glass fibers
especially of type E , R or S2, carbon fibers, boron fibers or
silica fibers.
[094] The fibrous substrate of the present invention is chosen from
vegetable fibers, wood fibers, animal fibers, mineral fibers,
synthetic polymeric fibers, glass fibers, carbon fibers or
mixtures thereof.
[095] Preferably the fibrous substrate is chosen from mineral
fibers .
[096] The fibres of the fibrous material have a diameter between
0.005 m and I OOm , preferably between I m and 50m , more
preferably between 5m and 30m and advantageously between I Om
and 25m .
[097] Preferably the fibres of the fibrous material of the present
invention are chosen from continuous fibres (meaning that the
aspect ratio does not apply as for long fibres) for the one
dimensional form, or long or continuous fibres forming the two or
three dimensional form of the fibrous substrate.
[098] The quantity of the initiating system is from 2.1 parts by
weight to 26 parts by weight in view of the sum of the
(meth) acrylic monomer and a (meth) acrylic polymer, the last two
together make up 100 parts by weight. The quantities are given in
view of the liquid (meth) acrylic syrup injected or used for
impregnation.
[099] The initiating system according to the invention comprises
From 0.1 to 5 part by weight of peroxy compound,
£ 1 parts by weight of accelerator calculated on the part
the transition metal in the accelerator,
from 1 to 10 parts by weight of at least one organic
aldehyde, and
from 1 to 10 parts by weight of at least one organic
peracide .
[100] Preferably the initiating system comprises:
from 0.5 to 3 part by weight of peroxy compound,
from 0.001-0.5 parts by weight of accelerator
calculated on the part of the transition metal in the
accelerator,
from 2 to 8 parts by weight of at least one organic
aldehyde, and
from 2 to 8 parts by weight of at least one organic
peracide .
[101] A s mentioned before the respective quantities can be prepared
in a two component system in order to avoid the polymerisation
while handling all components during the preparation and waiting
time before injection or impregnation.
[102] Once the application all components can be mixed together a
recipient in order to obtain the liquid (meth) acrylic syrup
according to the invention. Or the components are mixed in a
mixing head or device just a few moments before injection or
impregnation in order to obtain the liquid (meth) acrylic syrup
according to the invention. By a few moments is meant a time less
then 30 minutes preferably less then 10 minutes.
[103] 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 10 to 60 part by weight of (meth) acrylic
polymer,
b ) from 40 to 90 parts by weight of (meth) acrylic
monomer,
c ) from 2.1 to 26 parts by weight of one
initiating system for starting the polymerization
of the (meth) acrylic monomer,
said initiating system comprises at least one accelerator, at
least one organic aldehyde and a peroxy compound and organic
peracid, characterized that the peroxy compound is a liquid at
least at a temperature range between 0°C and 50°C
[104] Another additional aspect according to the present invention
is the impregnation liquid (meth) acrylic syrup for implementing
the impregnation process, said liquid (meth) acrylic syrup
comprises :
a ) a (meth) acrylic polymer,
b ) a (meth) acrylic monomer,
c ) at least one 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
mPa*s and said initiating system comprises at least one
accelerator, at least one organic aldehyde and a peroxy compound
and organic peracid, characterized that the peroxy compound is a
liquid at least at a temperature range between 0°C and 50 °C.
[105] Still another additional aspect according to the present
invention is an impregnation liquid (meth) acrylic syrup
comprising :
a ) from 10 to 60 part by weight of (meth) acrylic
polymer,
b ) from 40 to 90 parts by weight of (meth) acrylic
monomer,
c ) from 2.1 to 26 parts by weight of one
initiating system for starting the polymerization
of the (meth) acrylic monomer,
said initiating system comprises at least one accelerator, at
least one organic aldehyde and a peroxy compound and organic
peracid, characterized that the peroxy compound is a liquid at
least at a temperature range between 0°C and 50°C
[106] 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.
[107] Preferably the impregnation of the fibrous substrate in step
a ) is made in a closed mold.
[108] Advantageously the step a ) and step b ) are made in the same
closed mould.
[109] With regard to manufacturing process for manufacturing
mechanical or structured parts or articles comprising the polymeric
composite material, several methods could be used in order to
prepare three-dimensional mechanical or structured parts. One can
mention infusion, vacuum bag moulding, pressure bag molding,
autoclave molding, resin transfer moulding (R T ), reaction
injection molding (RIM) reinforced reaction injection molding (RRIM)
and variants thereof, press molding or compression molding.
[110] The preferred manufacturing process for manufacturing
mechanical or structured parts or articles comprising the composite
materials are processes were the liquid (meth) acrylic syrup
transferred to the fibrous substrate by impregnating the fibrous
substrate in a mold more preferably in a closed mold.
[Ill] Advantageously the impregnation step of the fibrous material
is made in a closed mold.
[112] 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.
[113] All processes comprise the step of impregnating the fibrous
substrate with the liquid (meth) acrylic syrup according to the
invnetion before the polymerization step in a mold.
[114] The step of polymerising of the liquid (meth) acrylic syrup
impregnating said fibrous substrate takes place after the
impregnation step in the same mold.
[115] Resin transfer molding is a method using a two sided mold set
which forms both surfaces of composite material. The lower side is
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
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
from vacuum infusion to vacuum assisted resin transfer moulding
(VARTM) . This process can be performed at either ambient or
elevated temperature.
[116] 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
mold by application of a slight vacuum. The fibrous substrate is
infused and completely impregnated by the liquid (meth) acrylic
syrup .
[117] One advantage of this method is the high amount of fibrous
material in the composite.
[118] 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.
[119] 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.
[Examples]
[120] Example 1 (comparative) : A syrup is prepared by dissolving 25
parts by weight of the P A (BS520 a copolymer of A comprising
ethyl acrylate as a comonomer) in 75 parts by weight of methyl
methacrylate, which is stabilized with EHQ (hydroquinone
monomethyl ether) . To the 100 parts by weight of the syrup are
added 0.8 parts by weight of benzoyl peroxide (BPO - Luperox A75
from ARKEMA) and 0.3 parts by weight of D PT (N, N-dimethyl-ptoluidine
from Sigma-Aldrich) . The syrup has a dynamic viscosity of
520 mPa*s at 25°C. The powder of benzoyl peroxide is not completely
dissolved on the syrup. Once the agitation is stopped solid particles
are still visible and they settle at the bottom of the recipient.
[121] The syrup is polymerized in a recipient of 100ml of volume at
a surrounding temperature or 25±1°C. The temperature is measured
with aid of a temperature detector put inside the syrup. After 40
minutes the temperature arrives at a peak.
[122] Example 2 (comparative) : The same basic syrup based on MMA
and PMMA as in example 1 is prepared. To the 100 parts by weight
of the syrup are added 1 part by weight of methyl ethyl ketone
peroxide a liquid product (MEKP - Luperox K12 from ARKEMA) and
0.018 parts by weight based on the cobalt of cobalt octoate (from
Sigma Aldrich) . The syrup is transparent.
[123] The syrup is polymerized in a recipient of 100ml of volume at
a surrounding temperature or 25±1°C. The temperature is measured
with aid of a temperature detector put inside the syrup. The
temperature arrives at a peak after more then 24 hours.
[124] Example 3 (comparative) : The same basic syrup based on A
and P A as in example 1 is prepared. To the 100 parts by weight
of the syrup are added 1 part by weight of methyl ethyl ketone
peroxide a liquid product ( EKP - Luperox K12 from ARKEMA) and
0.018 parts by weight based on the cobalt of cobalt octoate (from
Sigma Aldrich) , 2.5 parts by weight of lemarone (from Sigma
Aldrich), 2.5 parts by weight of phenyl acetaldehyde (from Sigma
Aldrich) . The syrup is transparent.
[125] The syrup is polymerized in a recipient of 100ml of volume at
a surrounding temperature or 25±1°C. The temperature is measured
with aid of a temperature detector put inside the syrup. After 97
minutes the temperature arrives at a peak.
[126] Example 4 (according to the invention) : The same basic syrup
based on MMA and PMMA as in example 1 is prepared. To the 100
parts by weight of the syrup are added 1 part by weight of methyl
ethyl ketone peroxide a liquid product (MEKP - Luperox K12 from
ARKEMA) 0.1 parts by weight based on the copper of copper based
activator (Nouryact CF12 from AKZO) , 2.5 parts by weight of
lemarone (from Sigma Aldrich), 2.5 parts by weight of phenyl
acetaldehyde (from Sigma Aldrich) and 5 parts by weight of
peracetic acid (from Sigma Aldrich) . The syrup is transparent.
[127] The syrup is polymerized in a recipient of 100ml of volume at
a surrounding temperature or 25±1°C. The temperature is measured
with aid of a temperature detector put inside the syrup. After 75
minutes the temperature arrives at a peak.

Claims
Liquid (meth) acrylic syrup comprising:
a ) a (meth) acrylic polymer,
b ) a (meth) acrylic monomer,
c ) at least one initiating system for starting the
polymerization of the (meth) acrylic monomer,
characterized that said initiating system comprises at least
one accelerator, at least one organic aldehyde and a peroxy
compound and organic peracid characterized that the peroxy
compound is a liquid at least at a temperature range between
0°C and 50°C.
The liquid (meth) acrylic syrup according to claim 1
comprising :
a ) from 10 to 60 part by weight of (meth) acrylic
polymer,
b ) from 40 to 90 parts by weight of (meth) acrylic
monomer,
c ) from 2.1 to 26 parts by weight of one
initiating system for starting the polymerization
of the (meth) acrylic monomer.
The liquid (meth) acrylic syrup according to claim 1 or 2
characterized that the initiating system is comprising:
from 0.1 to 5 part by weight of peroxy compound,
£ 1 parts by weight of accelerator calculated on the
part of the transition metal in the accelerator,
from 1 to 10 parts by weight of at least one organic
aldehyde, and
from 1 to 10 parts by weight of at least one organic
peracide
in view of the sum of the (meth) acrylic monomer and a
(meth) acrylic polymer, the two together make up 100 parts by
weight
WO 2014/174098 PCT/EP2014/058500
The liquid (meth) acrylic syrup according to any o f claims 1
to 3 characterized that the accelerator comprises a transition
metal compound.
The liquid (meth) acrylic syrup according to claim 4
cchhaarraacctterized that the transition metal is chosen from the 4
period .
6 . The liquid (meth) acrylic syrup according to any o f claims 4
to 5 characterized that the the transition metal is chosen
from Manganese, Cobalt, Iron or Copper and preferably
Manganese, Iron, Copper or mixtures thereof.
The liquid (meth) acrylic syrup according to any claims 1
to 6 characterized that the peroxy compound is organic
peroxide comprising from 2 to 30 carbon atoms.
8 . The liquid (meth) acrylic syrup according to any o f claims 1
to 8 characterized that the organic aldehyde has the general
formula R1CHO characterized that R l is an is an organic rest
comprising between 1 and 3 0 carbon atoms.
9 . The liquid (meth) acrylic syrup according to any o f claims 1
to 8 characterized that the organic peracid has the general
formula R1COOOH characterized that R l i s an i s an organic rest
comprising between 1 and 3 0 carbon atoms.
10. The liquid (meth) acrylic syrup according to any o f claims 1
to 9 characterized that liquid (meth) acrylic syrup has a
dynamic viscosity o f 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, measured at 25°C.
11. A process for polymerizing a liquid (meth) acrylic syrup
comprising:
a ) a (meth) acrylic polymer,
b ) a (meth) acrylic monomer,
c ) at least one initiating system for starting the
polymerization of the (meth) acrylic monomer,
said initiating system comprises at least one accelerator, at
least one organic aldehyde and a peroxy compound and organic
peracid characterized that the peroxy compound is a liquid at
least at a temperature range between 0°C and 50 °C,
characterized by mixing the components of a ) , b ) and c ) a few
moments before injection in a mold or impregnation of a
fibrous substrate.
12. The process according to claim 11, characterized that said
liquid (meth) acrylic syrup comprises:
a ) from 10 to 60 part by weight of (meth) acrylic
polymer,
b ) from 40 to 90 parts by weight of (meth) acrylic
monomer,
c ) from 2.1 to 26 parts by weight of one
initiating system for starting the polymerization
of the (meth) acrylic monomer.
13. 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 initiating system for starting the
polymerization of the (meth) acrylic monomer,
characterized that said initiating system comprises at least
one accelerator, at least one organic aldehyde and a peroxy
compound and organic peracid characterized that the peroxy
compound is a liquid at least at a temperature range between
0°C and 50°C.
14. The impregnation process according to claim 13, characterized
that 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
100 mPa*s to 1000 mPa*s, measured at 25°C.
15. The impregnation process according to claim 13 or 14,
characterized that the (meth) acrylic polymer is a homo- or
copolymer of methyl methacrylate ( A ) or a mixture thereof.
The impregnation process according to any of claims 13 to 15,
characterized that the copolymer of methyl methacrylate (MMA)
comprises from 70% to 99.7% by weight, preferably from 80% to
99.7% by weight, advantageously from 90% to 99.7% by weight
and more advantageously from 90% to 99.5% by weight of methyl
methacrylate and from 0.3 to 30% by weight, preferably from
0.3% to 20% by weight, advantageously from 0.3% to 10% 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.
17. An impregnation liquid (meth) acrylic syrup for implementing
the impregnation process according to any of the preceding
claims, 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 initiating system comprises at least one accelerator, at
least one organic aldehyde and a peroxy compound and organic
peracid characterized that the peroxy compound is a liquid at
least at a temperature range between 0°C and 50°C and
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, measured at 25°C.
18. An impregnation liquid (meth) acrylic syrup according to claim
17, wherein said syrup comprises:
a ) from 10 to 60 part by weight of (meth) acrylic
polymer,
b ) from 40 to 90 parts by weight of (meth) acrylic
monomer,
c ) from 2.1 to 26 parts by weight of one
initiating system for starting the polymerization
of the (meth) acrylic monomer.
19. 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 according to any of claims 1 to 10,
b ) polymerising the liquid (meth) acrylic syrup
impregnating said fibrous substrate.
20. The process according to claim 19, characterized that the
impregnation of the fibrous substrate in step a ) is made in a
closed mold.
21. The process according to any of claims 19 to 20, characterized
that in step a ) and step b ) are made in the same closed mold.
22. The process according to any of claims 19 to 21, characterized
that the process is chosen from resin transfer molding or
infusion .
23. The process according to any of claims 19 to 22, characterized
the temperature of the polymerization is step b ) is below
40°C.
24. Three-dimensional mechanical or structured parts obtained by
the manufacturing process according to claims 19 to 23.
25. Part according to claim 24, which 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.