This invention pertains to the field of coating of articles made of thermoplastic or thermo-hardening resins, by using an acrylic film. It is particularly meant for a multilayer acrylic film to be used in decorative techniques in the course of moulding as well as for moulded objects that are coated.
So many objects made in resin or in thermoplastic material or thermo-hardened are found in the daily life of the consumer. These resins such as ABS (Acrylonitrile Butadiene Styrene), PVC (Polyvinyl Chloride), PC (Polycarbonate), PP (Polypropylene) and its mixtures have been widely used for a long time to manufacture objects and moulded pieces that are found in the inside and outside of cars, material used in caravans or trailers, and in parts of appliances commonly found in households. Their excellent mechanical properties as well as their large-scale manufacturing which lowers their sales price lead to their popularity among consumers.
However, the consumer would also like to see the outer aspect of this equipment improved so that the technical functionality of the equipment matches the aesthetical part. In this regard, one would like to hide the exterior aspect of an object made from thermoplastic resin, which is generally considered not very attractive to look at, by a coloured coating in acrylic resin, which is more pleasing to the eye. One may also like to see that an object made from thermoplastic resin that appears artificial, be made more natural and traditional looking, such as wood or leather.
Acrylic resins are thermoplastic polymers, which are widely used due to their exceptional optical properties. Also worth mentioning are their properties like shiny look, high level of transparency, having at least 90% of light transmission, their hardness, their ability for thermoforming, their resistance to ageing, in particular to atmospheric agents (particularly UV) and their ease in shaping.
It is for these technical as well as aesthetic reasons that objects made out of thermoplastic resins or thermo-hardened are frequently covered by a film of acrylic
resin. This film allows a protective cover over the substrate against atmospheric agents and thus improves the durability of the objects or of the corresponding parts.
Among the suitable techniques of shaping is the decoration technique during the moulding stage, also known as the "in-mould decoration".
According to this technique, an acrylic film, preferably stocked in a roll, is in the first stage of the process pre-shaped according to the required measurements so as to fit the internal surface of the mould, which shall be used to shape the required object. (This is preceded by continuously hot sticking with another film cover or thermoplastic substrate in another stage called roll bonding.) In the second stage, the melted thermoplastic resin will be poured into the mould so that the film comes in contact and sticks to the surface of the object that has been formed.
One form of manufacturing technique that is used includes the simultaneous starting of the 2 stages, described above, by a suitable device. This form of manufacturing is known as the Film Insert Moulding or FIM.
Acrylic films, in this technique, can be used as they are, i.e. retaining their transparency. They can also be coloured and remain shiny. They can also, through printing, have a drawing, a pattern, a picture, letters, text or a logo that imparts specific information to the consumer. Any drawing, which renders the physical appearance of wood or of leather, can be an example of printing.
The drawings or patterns printed on the transparent acrylic film cover can be applied on the surface of the thermoplastic resin object by the FIM method. The printed film improves the durability of the coated object. Moreover, the film, which has the pattern or the printed drawing on the two surfaces in contact with the substrate, also protects the pattern from atmospheric agents. It also adds a raised pattern to the drawing that is rather pleasing.
[Previous article]
The US 6147162 patent applies to a mono-layered acrylic film made out of a mixture comprising 50% to 95% of a particular acrylic resin and 5% to 50% of a multi-layered acrylic polymer containing an electrometric layer. The aforesaid polymer, (also known in the trade as impact modifier), is dispersed into the acrylic resin. This film is suited to the FIM technique and gives a good surface hardness to the coated object.
The EP 1000978 patent applies also to an acrylic film made out of a mixture comprising 50% to 95% of a particular acrylic resin and 5% to 50% of the impact modifier suitable for surface covering through the FIM technique and having an improved surface hardness. This document also mentions about a laminated film (multilayer film) and more specifically a bi-layer film with an internal layer made out of the previously described mixture and an external layer made of an acrylic resin with an impact modifier. This bi-layer film, having an excellent surface hardness can also be shaped into a roll.
The US 6444298 Bl patent applies to a laminated acrylic film (or even a multi-layer film) comprising of a layer containing acrylic resin and acrylic elastomer particles (corresponding to an impact modifier), known as flexible layer and a layer containing acrylic resin without an impact modifier, known as surface layer. A three-layer system is also revealed in which two surface layers are separately stuck on the two surfaces of the flexible layer. Such a multi-layer film allows a better colour treatment (particularly by water immersion), avoiding bleaching and the weakening of the resin colouring linked to the impact modifiers. This patent advises that the percentage of flexible layer thickness over the total film thickness be more than 50% or preferably be even 60%.
The US 2002/0136853 AI application applies to a multi-layer acrylic film (bi- or tri-layer). The tri-layer film comprises of a flexible layer composed of an acrylic resin, acrylic elastomer particles and of two surface layers composed of acrylic resin or
acrylic elastomer particles. It is advisable that the percentage of thickness of the flexible layer over the total film thickness exceeds 50%, preferably higher than 80%.
Moreover, the previously mentioned printing techniques on the acrylic film require that under a highly automated industrial procedure, the progression of the film in the rotary press undergo very high traction levels. In order to resist, it must undergo a high elongation before rupture (measured at surrounding temperature level), which should, for instance, exceed 50% or should be preferably 55%.
The path of the film between the cylinders of the printing device and its capacity to coil itself in a roll so as to continuously supply such devices also require a very high degree of flexibility, corresponding to an elastic traction module (or Young module) lying between 500 and 1800 MPa or preferably between 700 and 1200 MPa.
However such a high Young module often leads to an excessively supple film, which negatively affects the resistance of the film against scratches or lines due to a decreased hardness. The appearance of lines is to be avoided not only for aesthetic reasons but also because the substrate then gets exposed to atmospheric agents such as UV radiation and is likely to be less durable.
This invention is designed to obtain an acrylic film, which, while maintaining its transparency, also has an excellent surface hardness enabling it to be more resistant to scratches and lines. It also has a very high level of elongation prior to rupture (enabling greater resistance in the printing machinery) combined with an elastic module having a very high order of flexibility required to stock the film in roll form. This objective has been attained, fully or partly, by the multi-layer acrylic film that is described henceforth. In the following text, all the indicated percentages are, in the absence of any further specification, to be deemed as weight percentage.
[DESCRIPTION]
This invention has been designed to obtain a multi-layer acrylic film with a thickness lying between 40 and 300 im, preferably between 70 and 100 im, comprising the following and in the order given below:
14. layer A made out of an acrylic thermoplastic mixture (A) comprising of a
methacrylic (co) polymer consisting mainly of methyl methacrylate patterns.
15. layer Bl made out of a (BI) mixture comprising of 10% to 50% of a
methacrylic (co) polymer consisting mainly of methyl methacrylate patterns and 50%
to 90 % of a composite impact modifier;
16. layer C made out of a (C) acrylic thermoplastic mixture comprising of a
methacrylic (co) polymer consisting mainly of methyl methacrylate patterns;
The A, BI and C layers being interlinked through their respective contact zones and the proportion of Bl thickness on the total multi-layer film thickness lying between 85% and 99 %, preferably between 88% and 95% and even better being between 88% and 92%.
As per variant, the invention is designed for a multi-layer acrylic film, having a thickness between 40 and 300 im, preferably between 70 and 100 im, comprising the following and in the order given below:
- layer A made from an (A) acrylic thermoplastic mixture consisting of a
methacrylic (co) polymer containing mainly methyl methacrylate patterns. ;
- layer B2 made from a (B2) mixture likely to be obtained through a procedure
consisting of:
1) Preparation by sequential polymerisation in aqueous emulsion: a) of an initial copolymer, in reaction to the monomers system comprising:
- 75% to 99.8 % of, as a minimum, an acrylate of an alkyl group containing
between 1 to 8 carbon atoms, and
- 0.1% to 5% of a cross linking agent selected from polyacrylic esters and
polymethacrylic polyols, the di or trivinyl benzenes or vinylic esters,
- 0.1% to 20% of, as a minimum, a grafting agent selected from the allelic
esters, methallylic or crotonic of monocarboxylique acid or unsaturated dicarboxilic a,
a-; then
b) of a second copolymer, in presence of an aqueous system as the result of
stage a), as reaction to a monomers system consisting of:
- 10% to 90% of, as a minimum, an initial acrylate of an alkyl group
containing between 1 to 8 carbon atoms, and
- 9% to 89.9% of, at least a second acrylate of an alkyl group containing
between 1 to 8 carbon atoms, separate from the first, and
- 0.1% to 1% of, at least a grafting agent selected from among the allylic
esters, methallylic, crotonic of monocarboxylic acid or unsaturated dicarboxylic a, a;
then
c) of a third copolymer, in presence of an aqueous system as the result of
stage b), as a reaction to the monomers system consisting of:
- 5% to 40% of at least an acrylate of an alkyl group containing between 1
to 8 carbon atoms, and
- 60% to 95% of at least a second acrylate of an alkyl group containing
between 1 to 8 carbon atoms, separate from the first; then
d) of a fourth polymer, in presence of an aqueous system as the result of
stage c), as a reaction to the monomers system consisting of:
- 80% to 100 % of at least an acrylate of an alkyl group containing between
1 to 8 carbon atoms and
- 0% to 20% of at least a second acrylate of an alkyl group containing
between 1 to 8 carbon atoms, separate from the first;
knowing that:
- The weight of the copolymer obtained at stage a) is between 10% to 75 %, and
- The total weight of copolymers introduced in the course of stages b), c), d) are
between 25% to 90%, in comparison to the total weight of the mixture comprising of
4 copolymers obtained after stage d); then
2) drying of the aqueous emulsion so obtained; then
3) if required, the shaping of granules of the dried product;
- if required layer C made from an acrylic thermoplastic mixture (C)
consisting of a methacrylic (co) polymer containing mainly of methyl methacrylate
patterns ;
Layers A, B2 and possibly C being interlinked through their respective contact zones and the ratio of the thickness of layer B2 over the total thickness of the multi-layer film falls between 85% and 99%. It could preferably be between 88% and 95%, and even better between 88% and 92%.
According to another variant, this invention has been designed to obtain a multi-layer acrylic film with a thickness between 40 and 300 µm, or preferably between 70 and 100 µm, comprising the following in the order mentioned below:
- layer A made from an (A) acrylic thermoplastic mixture consisting of a
methacrylic (co)polymer containing mainly methyl methacrylate patterns;
- layer B3 made out of a (B3) mixture comprising of 0% to 5% by weight of
at least one A polymer and of 95% to 100% by weight of at least one copolymer of
formula block B(-A)n composed of a B block and of n number of blocks A obtained
by radical polymerization controlled through a formula alcoxyamine I(-T)n in which
I designates a multivalent group, T a nitroxide and n an upper integer or equal to 2 ;
- if required layer C made out of a composition of acrylic thermoplastic (C)
comprising of a methacrylic (co)polymer consisting mainly of methyl
methacrylate patterns ;
The layers A, B3 and finally C being interlinked through their respective contact zones and the ratio of thickness of B3 to the total thickness of multi-layer film falls between 85% to 99%, preferably between 88% and 95% and even better between 88% and 92%.
The layer C is compulsory when layer B is made from (Bl), and optional when layer B is made from (B2) or from (B3).
It appears to be very important to properly adjust the thickness of layer Bl (or B2 or B3) as compared to the total thickness, so as to allow enough flexibility of the acrylic multi-layer film while retaining simultaneously an elongation prior to the rupture. The film, due to this invention, can thus be coiled and later on used in the rotary press. It has a good resistance level against the formation of lines and also a good transparency. The applicant found that a compromise of properties is obtained when the ratio of the thickness of the layer Bl (or B2 or B3) over the total thickness lies between 85% and 99%, preferably between 88% and 95 %, and even better if its between 88% and 92%.
Because of a combination of qualities like surface hardness, elongation prior to rupture and modulus of elasticity, the multi-layer acrylic film described under its three variants possesses a special adaptability for resin coating applications for a diverse range of objects, particularly by the industrial technique of moulding decoration. Due to its high level of transparency, combined with its properties of elongation prior to rupture, the film is also suitable for design or pattern printing by high-speed industrial printing methods, where the designs are clearly visible after the objects are coated by the thermoplastic resin film. This imparts a relief effect and is also visually pleasing to the consumer.
[Detailed Description]
The methacrylic (co)polymer of layer A and finally those of C, and also for (Bl) composition of layer B consists mainly of methyl methacrylate patterns. This methacrylic (co)polymer, thus defined, is also known as "acrylic matrix". It contains between 51% to 100% of methyl methacrylate patterns and 0% to 49% of ethylenic unsaturated copolymerizable co monomer patterns with methyl methacrylate.
The ethylene unsaturated copolymerizable monomer along with methyl methacrylate are selected from among:
14. The acrylic monomers of formula CH2=CH-C(=O)-O-R1 where R, designates a hydrogen atom, a linear, cyclical or ramified C1-C40 alky I group,
possibly substituted by an atom of halogen, a hydroxyl, alcoxy, cyano, amino •or epoxy group. It could, for instance, be acrylic acid, methyl acrylate, ethyl, propyl, n-butyl, isobutyl, tertiobutyl, 2-ethylhexyl, glycidyl, acrylates hydroxyalkyl, acrylonitrile ;
15. The methacrylic monomers of formula CH2=C(CH3)-C(=O)-O-R2 where
R2 designates a hydrogen atom, a linear, cyclical or ramified C1-C40 alkyl
group, possibly substituted by an atom of halogen, a hydroxyl, alcoxy, cyano,
amino or epoxy group. It could, for instance, be methacrylic acid, methyl
methacrylate, ethyl, propyl, n-butyl, isobutyl, tertiobutyl, 2-ethylhexyl,
glycidyl, hydroxyalkyl methacrylate, methacrylonitrile ;
16. Aromatic vinyl monomers. It could, for instance, be styrene, substituted
styrenes such as alpha-methylstyrene, monochlorostyrene, tertbutyl styrene.
The acrylic matrix used for the manufacturing of film layers by the invention is generally obtained in the form of pearls or granules. The pearls are obtained by the well-known polymerization technique in an aqueous suspension of monomers, in the presence of a solvent initiator in the monomers and of a suspension agent. The granules can be extracted from the pearls, which have been melted in an extruder to form bands, which are afterwards cut. The granules can also be prepared by a mass polymerization process, a well-known technique that consists of polymerizing the monomers or dissolved pre-polymer syrup in the monomers, in the presence of an initiator and of a chain transfer agent so as to control the molecular mass of the polymer. The polymer obtained, is forced at the end of line, in a die in order to obtain an extruded string, which can later be cut into granules.
Layer A, layer Bl made from composition (Bl), and, if need be, layer C of the multilayer film according to the invention, are prepared from the acrylic matrix as described earlier, knowing that the nature of the aforementioned matrix may be identical or different to the related layers of a same multi-layer film. For logical industrial reasons, one generally prefers using the same acrylic matrix for layers A and C. Layer C is optional in case layer B2 or B3 is used.
Preferably, an acrylic matrix is used for the manufacturing of composition (Bl) of layer B1, and/or for the manufacturing of layer A and/or C, a copolymer consisting of 80% to 99% by weight of methyl methacrylate pattern, and of 1% to 20% of (meth) acrylic acid or an ester corresponding to an alkyl group consisting between 1 to 4 carbon atoms. According to a preferred variant, the comonomers associated with methyl methacrylate pattern are acrylic acid, methyl acrylate or ethyl acrylate. Ideally, it is ethyl acrylate.
As per a preferred variant, Bl layer, as defined previously, is used. Apart from the acrylic matrix, it contains at least one impact modifier.
A composition (Bl) consisting of 30% to 50% of the acrylic matrix and of 50% to 70% of impact modifier is generally preferred. The impact modifier has a many-layered structure, at least one of them being composed of an elastomer phase. Considering that it is this elastomer phase in the modifier that leads to shock resistance, this additional component is added to the acrylic matrix so as to obtain a suitable proportion of the elastomer.
The impact modifier that is being used in the invention can be composed of a sequenced copolymer consisting of at least one elastomer sequence as a result of the polymerization of monomers such as butadiene, substituted or not, alkyl acrylates or aralkyle. It could be more specifically a bi-sequenced copolymer such as poly (butadiene-block-methyl methacrylate) or a tri-sequenced copolymer such as poly (styrene-block-butadiene-block-methyl methacrylate) in which the elastomer polybutadiene phase represents upto 50% by weight of the mass of sequenced copolymer. The butadiene sequence may be non-hydrogenized, partially or totally hydrogenized. It can also be a poly (methyl methacrylate-block-butyle acrylate-block-methyl methacrylate), copolyetheresteramides with polyamide sequences and polyethers, copolymers with polyesters sequences and polyethers.
The impact modifier may also be a polymer substance with a many-layered structure, consisting of at least one elastomer phase. These polymer substances can thus be
particles obtained by coagulation or by drying (in particular by pulverization or atomisation) of elastomer latex. The manufacture of such latex, used as reinforcement against thermoplastic matrix shock, is a well-known procedure. It is a well-known fact that by modifying the manufacturing conditions of latex, it is possible to change their morphology and subsequently, their capability to improve their shock resistance and their capability of maintaining the optical properties of the acrylic matrix that needs to be reinforced. The size of these many layered structures lies generally between 60 and 5000 nm, preferably between 80 and 300 nm.
The various morphologies of elastomer latex, which have been discovered to date, can be safely used within the framework of this invention. In particular, one may use a latex of "soft-hard" morphology in which the first phase (or core) is elastomer and in which the last "hard" phase (or external layer) is a rigid thermoplastic. The term rigid thermoplastic means a (co) polymer in which the glass transition temperature or Tg is above or equal to 25 °C.
The latex may be obtained in the following two stages:
- in the first stage, through emulsion polymerization, in an aqueous milieu, in
presence of an initiator generating free radicals and an emulsifying agent of at least
one monomer (called "soft" i.e. a monomer leading to a polymer which has a glass
transition temperature below 25°C) which will form the elastomer phase, selected
from monomers like butadiene, substituted or not, alkyl acrylate or aralkyl in which
the alkyl group contains between 4 to 15 carbon atoms, then
- in the second stage, again through emulsion polymerization in an aqueous
milieu, in the presence of the first stage polymer, of at least one monomer which will
form the "hard" phase compatible with the acrylic matrix that needs to be more shock
resistant. This or these monomers (termed as "hard", i.e. leading to a polymer after
polymerization, with a glass transition temperature above or equal to 25°C) can be
selected from among the alkyl methacrylate within which the alkyl group contains
between 1 to 4 carbon atoms, aromatic vinyl monomer such as styrene and substitute
styrenes, acrylonitrile monomers and methacrylonitrile.
The "hard" phase can also be obtained from a mixture of previous hard monomers (in high proportion) and of ethylenic unsaturated comonomers, such as a lowered alkyl acrylate or (meth)acrylical acid.
The polymerization of monomers which do not form part of the final "hard" phase must be done in presence of crosslinking monomers and possibly in front of graft monomers. These crosslinking and graft monomers are multi-functional ethylenic unsaturated copolymerizable monomers along with the monomers that do no form part of the "hard" phase.
The copolymer comprising the final "hard" phase must therefore, be formed in presence of a crosslinking monomer. The commonly used crosslinking monomers are the polycrylates and polymethacrylates of polyols, such as diacrylates and alkylene glycol dimethacrylates.
If needed the graft monomers that may be used are allyl esters such as acrylate and allyl methacrylate.
One particular manner of manufacturing a "soft-hard" impact modifier composition is done in the following way. The elastomer phase is prepared from a mixture containing at least 50% alkyl acrylate or aralkyl within which the alkyl group contains as many as 4 to 15 carbon atoms, between 0.05% to 5.0 % of crosslinking monomer, between 0.05% to 5% of graft monomers, between 0% to 10% of hydrophilic monomer (such as amides and hydroxy alkylic esters of methacrylic acid, (meth)acrylic acid) and the remaining portion being composed of other ethylenic unsaturated copolymerizable monomers (such as styrene). The final rigid thermoplastic phase, polymerized in presence of the elastomer phase, can be obtained from a mixture made of monomers comprising of at least 50% alkyl methacrylate by weight. The elastomer phase and the thermoplastic phase allow nearly 20% minimal degree of chemical linking.
Another impact modifier component that can be incorporated into the (Bl) composition is the "hard-soft-hard" morphology-type latex. In such a structure, the
first phase (or core), non-elastomer is polymerized by monomers, which may form the acrylic matrix, to be reinforced or the final "hard" phase, as defined previously. As also defined earlier, the intermediate phase is elastomer and obtained from the so-called "soft" monomers. Finally, the last phase is formed also from the usable monomers for the first phase.
A latex such as the one described in the US 3793402 patent is suitable and is formed by:
(1) a non elastomer core, composed of a copolymer obtained from:
- 80% to 100% of at least one "hard" monomer like alkyl methacrylate (alkyl
in C1-C4), styrene, (meth)acrylonitrile possibly linked (to the level of 0% to 30%) to
one or many ethylenic unsaturated comonomers such as lower alkyl (meth)acrylate
(alkyl in C1-C4) and (meth)acrylic acid,
- 0% to 10% by weight of crosslinking multifunctional monomer and
- 0% to 10% by weight of graft monomer, such as those previously
mentioned,
(2) mid-level elastomer layer, formed in presence of polymer (1), from
- 50% to 99.9% of butadiene monomers, substituted or not, and/or alkyl
acrylate within which the alkyl group contains between 1 to 8 carbon atoms,
- 0% to 49.9% of ethylenic unsaturated comonomers such as the lower alkyl
(meth)acrylates (alkyle in C1-C4), (meth)acrylic acid and and styrene,
- 0% to 5% by weight of a crosslinking multifunctional monomer and of
- 0.05% to 5% by weight of graft monomers, such as those previously
mentioned,
(3) an external layer called "hard" or formed by compatibilization, in
presence of polymers (1) and (2), from "hard" monomers (alkyl methacrylate in C1-
C4, styrene, (meth)acrylonitrile) possibly linked to (at the rate of 0% to 30%)
ethylenic non saturation comonomers such as lower alkyl (meth)acrylate (alkyl in C1-
C4). In particular, the various phases, core (1), middle layer (2) and external layer (3)
respectively represent, in weight terms, 10% to 40%, 20% to 60% and 10% to 70% of
the total mass of the copolymer of the tri-layered or tri-phase composite.
Finally it is possible to incorporate in the composition (Bl) a product of so ft-hard-soft-hard morphology as has been described in the EP-B-270865 document which consists of (1) a central core based upon a crosslinking elastomer thoroughly mixed to a thermoplastic methacrylic (co)polymer resin, (2) a first layer of the mentioned resin grafted to the central core, (3) a second layer of crosslinking elastomer grafted to the above mentioned first layer or the above mentioned core and (4) a third layer of resin grafted on the above mentioned second layer of crosslinking elastomer.
Other usable morphologies are the more complex ones described in patents US-A-4052525 and FR-A-2446296.
The impact modifier incorporated in the composition (Bl) shows itself, to its advantage, under the form of a polymeric substance with a multi-layered structure. An impact modifier compound of "soft-hard" morphology is more specifically preferred.
The impact modifier DURASTRENGTH D320 from the Company ATOF1NA is particularly appreciated.
According to another variant, the layer (B2) is used such as defined earlier. We refer to the patent US 4141935 as regards the procedure to obtain the composition (B2).
In step (1) of the procedure described in the patent US 4141935, we prefer to use as a monomer in step (a) a radical alkyl acrylate containing from 4 to 8 atoms of carbon. As regards the crosslinking agents that we may add to the system of monomers, we may quote as examples polyacrylic and polymethacrylic esters of polyols : the di(meth)acrylate of butanediol, the tri(meth)acrylate of trimethylolpropane, and as an example of vinyl esters, vinyl acrylate.
As regards step (b), according to a preferred variation we use :
14. 10 to 90% of at least a first radical alkyl acrylate containing 1 to 4
atoms of carbon, and
15. 9 to 89.9% of at least a second radical alkyl acrylate containing 4 to 8
atoms of carbon, distinct from the first one.
According to another preferred variation of this step (b), whether taken in combination with the first one or not, we can add to the system of monomers from 0 to 5% of a crosslinking agent such as previously defined for step (a).
As regards, step (c), we prefer to use as a system of monomers :
16. atleast from 5 to 40% of a radical alkyl acrylate containing 4 to 8 atoms
of carbon, and
17. atleast from 60 to 95% of a second radical alkyl acrylate containing 1
to 4 atoms of carbon, distinct from the first one.
According to another preferred variant, whether or not taken in combination with the first one, we may add to the system of monomers, 0 to 5% of a crosslinking agent, and 0 to 1 % at least, a grafting agent such as previously defined for step (a), as well as 0 to 5% of a chain-limiting agent chosen from amongst the alkylmercaptans having 1 to 20 atoms of carbon.
As regards step (d), we prefer to use as a system of monomers :
18. at least 80 to 100% of one radical alkyl acrylate containing 4 to 8
atoms of carbon, and
19. at least 0 to 20% of a second radical alkyl acrylate containing 1 to 4
atoms of carbon, distinct from the first one.
According to another preferred variant of this same step (d), whether or not taken in combination with the previous one, we add to the systems of monomers being used, 0 to 5% of a crosslinking agent, 0 to 1% at least of a grafting agent, and 0 to 5% of a chain limiting agent such as previously defined for step (c), and 0 to 5% of (meth)acrylic acid.
According to another preferred variant of step (1) of the process to obtain the composition (B2), we use an alkylene diacrylate as a crosslinking agent, and an allyl (meth)acrylate of as a grafting agent.
Step (2) of the preparation of the composition (B2) consists of drying out the aqueous emulsion obtained at the end of step (1) by any means known to the people of the trade, specially coagulation or atomisation.
According to yet another variation, the B3 layer is manufactured from the composition (B3) which contains at least 0 to 5% in weight of a polymer A, and at least 95 to 100% in weight of a copolymer with B(-A)n blocks prepared by a controlled radical polymerization. The preparation of this polymer with blocks consists of:
- polymerizing to a temperature between 60 to 150°C a mix of B0 monomers in the
presence of an alkoxyamine with formula I(-T) n upto a 90% conversion rate, then
- eliminating a part of or all the B0 monomers that have not reacted, then
- adding and polymerizing a mix of A0 monomers, then
- eliminating a part of all the A0 monomers that have not reacted, and collecting the
copolymer B(-A)n.
The B block present in the copolymer with blocks included in the composition (B3) presents a glass transition temperature (Tg) of less then 0°C, an average mass in weight (Mw) of between 40,000 and 200,000 g/mol, and a polydispersity index (Ip) of between 1.1 and 2.5, and preferably between 1.1 and 2.0. This B block is obtained by the polymerisation of a mix of B0 monomers containing :
20. at least 60 to 100% in weight of a b] (meth)acrylic monomer with
formula CH2=CH-C(=O)-O-R, or CH2=C(CH3)-C(=O)-O-R, where R,
stands for a hydrogen atom, an alkyl grouping in linear, cyclical or
branched C1-C40, eventually / possibly substituted by a halogen atom, a
hydroxy, alcoxy, cyano, amino or epoxy grouping. This may be, for
example, acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, n-
butyl acrylate, isobutyl acrylate, tertiobutyl acrylate, 2-ethylhexyl acrylate,
glycidyl acrylate, hydroxyalkyl acrylates, acrylonitrile acrylates. We may
notably mention butyl acrylate, octyl acrylate, nonyl acrylate, 2-ethyl hexyl
acrylate, polyethylene glygol acrylate or acrylonitrile acrylate.
21. At least 0 to 40% in weight of another b2 monomer chosen from
amongst the polymerisable monomers by radical means such as the
ethylenic, vinylaromatic monomers and other such similar ones. This may
For a monomer(s) entering into the constitution of the B block, we prefer to use butyl acrylate and styrene.
Block A present in the copolymer with blocks comprised in the composition (B3) presents a glass transition temperature (Tg) greater than 50°C. Block A is obtained by the polymerization of a mix of A0 monomers containing :
22. at least 60 to 100% in weight of an a, (meth)acrylic monomer with
formula CH2=CH-C(=O)-O-R, or CH2=C(CH3)-C(=O)-O-R, where R,
stands for a hydrogen atom, an alkyl grouping in linear, cyclical or
branched C1-C40, eventually / possibly substituted by a halogen atom, a
hydroxy, alcoxy, cyano, amino or epoxy grouping. This may be, for
example, acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, n-
butyl acrylate, isobutyl acrylate, tertiobutyl acrylate, 2-ethylhexyl acrylate,
glycidyl acrylate, hydroxyalkyl acrylates, acrylonitrile acrylates. We may
notably mention butyl acrylate, octyl acrylate, nonyl acrylate, 2-ethyl hexyl
acrylate, polyethylene glygol acrylate or acrylonitrile acrylate.
23. At least 0 to 40% in weight of an a2 monomer chosen from among the
anhydrides such as maleic anhydride or vinylaromatic monomers such as
styrene or its derivatives, in particular alpha-methyl styrene.
As a monomer entering into the constitution of Block A, we prefer to use a mix of methyl methacrylate and butyl acrylate.
The alkoxyamine used has an I(-T)n formula wherein I is an organic grouping corresponding to one of the following formulae :
(Formula Removed)
where:
24. Ar stands for a substituted aromatic group;
25. Z is a multifunctional organic radical with molar mas greater than or
equal to 14, and
26. N is an integer greater than or equal to 12.
As possible definitions of Z, we may quote the following radicals or groupings :
27. a polyalcoxy grouping in particular dialcoxy, such as the radicals
OCH2CH2O-, -OCH2CH2CH2O-, -O(CH2)4O-, -O(CH2)5O, -O(CH2)6O-,
l,3,5-tris(2-ethoxy) cyanuric acid,
28. a polyaminoamine such as the polyethylene amines, l,3,5-tris(2-
ethylamino) cyanuric acid;
29. a polythioxy, phosphonate or polyphosphonate.
In the formula I(-T)n, n represents the functionality of the alcoxyamine, ie. The number of T nitroxide radicals that may be freed by the alcoxyamine according to the mechanism :
(Formula Removed)
This reaction is activated by the temperature. In the presence of monomer(s), the activated alcoxyamine energizes a polymerization. The diagram below shows the preparation of a copolymer A-B-A (or B(-A)2) from an alcoxyamine for which n=2. The mix of B0 monomers is first polymerized after activation of the alcoxyamine to give Block B, then once block B has been terminated, the mix of A0 monomers is then polymerized to give both blocks A. B is a polymer block directly related to I by a covalent relation, and which is obtained by the polymerization of a mix of B0 monomers. A is a polymer block linked directly to Block B by a covalent relation and which is obtained by the polymerization of a mix of A0 monomers :
(Formula Removed)
BlockA BlockB BlockC The principle of the preparation of polymers with blocks remains valid for n>2.
T stands for a nitroxide with formula :
(Formula Removed)
where Ra and Rb stands for identical or different alkyl groupings possessing 1 to 40 atoms of carbon, eventually linked amongst themselves so as to form a cycle, and eventually / possibly substituted by hydroxy, alcoxy or amino groupings;
and RL stands for a monovalent grouping with molar mass greater than 16 g/mol, and preferably greater than 30 g/mol. The RL grouping may have, for example, a molar mass comprised between 40 and 450 g/mol. This is preferably a phosphorous grouping with a general formula :
(Formula Removed)
where X and Y, being identical or different, may be chosen from among the alkyl, cycloalkyl, alkoxyl, aryloxyl, aryl, aralkyloxyl, perfluoroalkyl, aralkyl radicals, and may contain 1 to 20 atoms of carbon; X and/or Y may also be a halogen atom like a chlorine, bromine or fluorine atom.
In an advantageous manner, RL is a phosphonate grouping with formula :
(Formula Removed)
The RL grouping may also contain at least one aromatic cycle such as the phenyl radical or the naphtyl radical, substituted for example by one or more alkyl radicals containing 1 to 10 atoms of carbon.
The T nitroxide preferably used corresponds to the following formula :
(Formula Removed)
Or the following nitroxide :
(Formula Removed)
Preferably, the alcoxyamine is chosen from among the compounds corresponding to one of the following formulae :
(Formula Removed)
where Z and Ar are such as previously defined.
The following alcoxyamines are most specifically preferred :
(Formula Removed)
During the formation of the Block A, there may be a loss of control over the polymerization, notably on account of the mechanism described below, which corresponds to a transfer reaction to the nitroxide :
(Formula Removed)
During the formation of the Block A, the loss of control may cause formation of the polymer A. Hence we find in the composition (B3) 0 to 5% in weight of the polymer A for 95 to 100% of the copolymer with blocks B(-A)n.
The I grouping present in the copolymer with blocks comprised in the composition (B3) corresponds to one of the general formulae la, Ib or Ic such as previously
deftned. These compounds are received from the thermal decomposition of the alcoxyamine corresponding to the formula (IIa), (IIb) or (IIe). The radical Z included in the general formulae la, Ib or Ic is associated with n functions of acryl type in the formula la, to n functions of methacryl type in the formula Ib, and to n functions of styryl in Ic.
The average molecular mass in weight (Mw) of the copolymer with blocks B(-A)n is comprised between 80,000 g/mol and 300,000 g/mol with polydispersity between 1.5 and 2.5.
Given that the monomers received from Block B may enter into the composition of Block K, so as to describe completely the copolymer, it helps to specify its global content in monomers specific to Block B and the ratio between BlockB and Block A. These two rations are not necessarily equal. The copolymer B(-A)n contains between 60% and 10% in weight of the monomers of Block B and preferably between 50 and 25%. The proportion of Block b in the copolymer with blocks is comprised between 10 and 50%, preferably between 20 and 50%.
As an example of a copolymer with blocks B(-A)n we may quote the following tri-
block polymers (in this case n=2) :
PMMA-b-polyacrylate of n-butyl-b-PMMA
PMMA-b-poly(acrylate of n-butyl-c-styrene)-b-PMMA
PMMA-b-poly(acrylate of isobutyl-co-styrene)-b-PMMA
poly(methacrylate of methyl-co-acrylate of n-butyl)-b-poly(acrylate of n-butyl-co-
styrene)-b-poly(methacrylate of methyl-co-acrylate of n-butyl).
As regards the multilayered acrylic film, this is manufactured by coextrusion according to a standard technique in the field of thermoplastics. The compositions intended for the manufacture of A, B1-3 and if necessary C layers, films according to the invention / finding are generally presented in the form of granules. According to this technique, the materials corresponding to the different layers is forced (introduced
The association of the melted materials forms the multilayered film which is cooled by means of passing it over rollers with controlled temperatures. In adjusting the speed of the rollers placed longitudinally and / or in transversal manner, we can cause longitudinal and/or transversal stretching, according to the geometry used for the holes allows us to control the thickness of the different layers.
The thermoplastic compositions previously described to manufacture the different layers of multi-layered film (A, B1-3, C) may each contain the usual additives such as lubricant, UV stabiliser, antistatic, colour, antioxydant, minerals in a quantity of 0 to 5% weight as against the composition.
The present invention / finding is also intended for the use of multilayered acrylic film such as previously described for the decolouring technique during moulding of articles in thermoplastic resin, and more specifically for the technique of moulding with the simultaneous insertion of film.
According to the invention / finding, the film may also be used to recoat a substratum. As regards the substratum being recoated by the multi-layered acrylic film of the invention, this may be a substratum in thermoplastic resin. The thermoplastic resin may be :
30. a polyolefin such as that of polyethylene (eg. PEHD, metallocenic PE,
PELD, PELDL), of polypropylene, or an ethylene-propylene copolymer;
31. a chlorinated resin such as PVC, plastified PVC, chlorinated
polyethylene;
32. polycarbonate;
33. an acrylonitrile-butadiene-styrene resin (ABS);
34. a polymer or copolymer containing styrene such as polystyrene, SAN;
35. a saturated polyester (PET, PBT...);
36. a polymer of ethylene and of vinyl acetate (EVA) or of ethylene and
alkyl acrylate, eventually / possibly in the presence of a termonomer eg.
Maleic anhydride;
37. a polyamide or copolyamide;
38. a polyesteramide;
39. a copolymer of ethylene and of vinyl alcohol (EVOH);
40. a polyurethane.
We would not leave the context of the present invention in mixing a number of thermoplastic resins. Eg. A mix of two polyolefins, of polycarbonate and ABS.
The substratum may also be in a thermoset resin. This may be, for example :
41. phenolic resin;
42. epoxy resin;
43. melamine resin;
44. melamine-formaldehyde resin;
45. melamine-phenol resin;
46. urea formaldehyde resin.
A list of possible resins is provided in Ullman 's Encyclopaedia of Industrial Chemistry, 5th edition, Vol. A20, "Plastics, General Survey", p. 549-552.
The substratum may also be in wood / board, fibre building board, a cellulosic material, steel, aluminium, board recoated with melamine, melamine-formaldehyde or melamine phenol resin. Preferably, the acrylic film is used to recoat a thermoplastic resin, eg. according to the FIM technique.
The acrylic film of the invention may recoat the substratum and we hence obtain a 'multilayered structure of type :
Substratum / layer C / layer Bl / layer A
Substratum / layer C / layer B2 / layer A
Substratum / layer B2 / layer A
Substratum / layer C / layer B3 / layer A
Substratum / layer B3 / layer A.
An adhesive agent may eventually / possibly be used to ensure adhesion of the film on the substratum. The adhesive agent is hence placed between the substratum and the acrylic film. The following structures are hence obtained :
Substratum / adhesive agent / layer C / layer Bl / layer A
Substratum / adhesive agent / layer C / layer B2 / layer A
Substratum / adhesive agent / layer B2 / layer A
Substratum / adhesive agent / layer C / layer B3 / layer A
Substratum / adhesive agent / layer B3 / layer A.
The adhesive agent may be made of a glue or a polymer film allowing to ensure adhesion between the substratum and the layer of acrylic film in contact with the substratum.
[Example]
The following example is being given on a purely illustrative basis, and should not in any case be considered limitative.
The methods for evaluation of the multilayered film are the following :
47. degree of transparency (or Haze) : ASTM D1003
48. elongation upon break, and elastic module : ASTM D882
49. hardness of the surface : ASTM D3363-00
50. shine (or gloss) : ASTM D523
Layers A and C :
We use a copolymer containing 95% of methyl methacrylate patterns and 5% acrylate of ethyl, which is commercially available in the form of granules (Altuglass® V044 from the company ATOGLAS).
Layer B:
As an acrylic matrix, we use a copolymer containing 75% in weight of methyl methacrylic patterns and 25% of acrylate of ethyl, in the form of granules.
As an impact modifier, we use a bi-layer system SOFT/HARD where the soft core is a copolymer of butadiene and of acrylate of butyl, and the hard skin is a homopolymer of methyl methacrylate which is commercially available under the
name Durastrength® D320 with the company Atofina.
We mix the impact modifier the granules of the acrylic matrix, so as to have 60% impact modifier content in weight. The mixture is effected at approx. 200 degrees C in a twin-screw extruder, resulting in a number of extruded trims which are then cut in the form of granules.
The granules meant for layer B are introduced into a single-screw extruder of 30mm diameter and the granules meant for layers A and C are introduced into 2 single-screw extruders of 20mm diameter. These three extruders input a coextrusion cavity of annular shape and 50mm diameter, heated to 240 degrees C. The adhesion between the three layers is then effected in the melted state.
The 3 layer film in the form of a cylinder is formed contiguously, stretched towards the top by an adapted device and inflated by air introduced from the interior of the cavity in annular shape. The sleeve of film hence formed is also cooled from the outside, by means of jets of air issued by a ring concentric to the annular cavity.
The sleeve of film is then cut according to a profiling plate, and the trilayer film is rolled onto a roll.
By microscopic optics, we measure the thickness of the 3 layers :
Thickness of layer A 7 µm
Thickness of layer B • 80 µm
Thickness of layer C 3 µm
The implementation of the previously identified evaluation methods, leads to the following results:
haze =1.7%
elongation at rupture — 57%
elastic module = 730 Mpa
hardness (pencil test) = 2H
gloss (measured at 60°)
The ratio between the thickness of the flexible layer against the total thickness is 88.9%. The total thickness is approximately 90 µm. The trilayer film hence obtained offers excellent flexibility and may be easily manipulated while preserving hardness and transparency.
Table I
(Table Removed)

WE CLAIM:
1. Acrylic multilayered film of a thickness between 40 and 300 µm, preferably between 70 and 100 µm, in the following order:
- layer A manufactured from a thermoplastic acrylic compound (A) consisting
of a methacrylic (Co)polymer mainly containing methyl methacrylate patterns;
- layer Bl manufactured from a compound (Bl) consisting of 10 to 50% of
methacrylic (co)polymer mainly containing methyl methacrylate patterns and 50 to
90% of a shock modifier ;
- layer C manufactured from an acrylic thermoplastic compound (C)
consisting of a methacrylic (co)polymer mainly containing methyl methacrylate
patterns;
the layers A, B1 and C are linked with each other in their respective contact zones and the thickness ration of layer B1 to the total thickness of the multilayered film comprises between 85 to 99%, preferably between 88 and 95% and still more preferably between 88 to 92%.
2. Film according to claim 1 in which the compound (Bl) consists of 30
to 50% of a methacrylic (co) polymer and of 50 to 70% of a shock modifier.
3. Film according to claim 2 in which the shock modifier is in the form of
a polymer substance having a structure composed of several layers.
4. Film according to claim 3 in which the shock modifier has a "soft-
hard" morphology.
5. Film according to claim 4 in which the shock modifier is
DURASTRENGTH 320.
6. Acrylic multilayered film having a thickness between 40 and 300 µm,
preferably between 70 and 100 µm, in the following order :
- layer A manufactured from a thermoplastic acrylic compound (A) consisting
of a methacrylic (co)polymer mainly containing methyl methacrylate patterns;
- layer B2 manufactured from a compound (B2) susceptible of being obtained
through a process consisting of :
1) the preparation of a block polymerization in an aqueous emulsion : a) of a first copolymer, by reaction of a monomer system comprising of :
- at least 75 to 99.8 % of an acrylate of an alkyl group containing between 1 to
8 carbon atoms,
- 0.1 to 5% of a crosslinking agent chosen from among polyhydric alcohol
polyacrylic and poly methacrylic esters, di or trivinyl benzenes or vinylic esters
- at least 0.1 to 20 % of a grafting agent chosen from amongst allylic or
methallylic esters or unsaturated a, a mono carbolic or di carbolic acid croton ; then
b) of a second copolymer, in the presence of an aqueous system resulting
from stage a), by reaction of a monomer system consisting of:
- at least 10 to 90 % of a first acrylate of an alkyl group containing between
1 to 8 carbon atoms, and
- at least 9 to 89.9 % of a second acrylate of an alkyl group containing
between 1 to 8 carbon atoms different from the first group, and
- at least 0.1 to 1 % of a grafting agent chosen from among amongst allylic
or methallylic esters or unsaturated a, a mono carbolic or di carbolic acid croton ; then
c) of a third copolymer, in the presence of an aqueous system resulting from
stage b), by reaction of a monomer system consisting of:
- at least 5 to 40 % of an acrylate of an alkyl group containing between 1 to
8 carbon atoms, and
- at least 60 to 95 % of a second acrylate of an alkyl group containing
between 1 to 8 carbon atoms different from the first group; then
d) of a fourth copolymer, in the presence of an aqueous system resulting
from stage c), by reaction of a monomer system consisting of:
- at least 80 to 100 % of an acrylate of an alkyl group containing between 1
to 8 carbon atoms, and
- at least 0 to 20 % of a second acrylate of an alkyl group containing between 1 to 8 carbon atoms different from the first group; it being made clear that: :
- the weight of the copolymer obtained in stage a) represents 10 to 75%, and
- the total weight of the copolymers introduced in stages b), c), d) represents 25 to
90 %, in ratio to the total weight of the compound comprising of the 4 copolymers
obtained after stage d); then

2) the drying of the aqueous emulsion thus obtained ; then
3) eventual putting into granular form of the product thus dried ;
- eventually a layer C manufactured from an acrylic thermoplastic compound
(C) consisting of a methacrylic (co)polymer mainly containing methyl methacrylate
patterns;
the layers A, B2 and C are linked with each other in their respective contact zones and the thickness ration of layer B2 to the total thickness of the multilayered film comprises between 85 to 99%, preferably between 88 and 95% and still more preferably between 88 to 92%.
7. Acrylic multilayered film having a thickness between 40 and 300 µm, preferably between 70 and µm, in the following order:
- layer A manufactured from a thermoplastic acrylic compound (A) consisting
of a methacrylic (co)polymer mainly containing methyl methacrylate patterns;
- layer B3 manufactured from a composition (B3) containing 0 to 5% in
weight of at least a polymer A and 95 to 100% in weight of at least a copolymer in
blocks having the formula B(-A)n composed of a block B and of n blocks of A
obtained by the radical polymerization controlled with the help of an alcoxyamine
having the formula I(-T)n in which I refers to an organic cluster, t a nittroyde and n an
integer greater than or equal to 2;
- eventually layer C manufactured from an acrylic thermoplastic compound
(C) consisting of a methacrylic (co)polymer mainly containing methyl methacrylate
patterns;
the layers A, B3 and C are linked with each other in their respective contact zones and the thickness ration of layer B2 to the total thickness of the multilayered film comprises between 85 to 99%, preferably between 88 and 95% and still more preferably between 88 to 92%.
14. Film according to claim 7 in which block B is obtained by the
polymerization of a monomer mix B0 consisitng of :
At least 60 to 100 % in weigh of a (meth) acrylic monomer bl having the formula CH2=CH-C(=O)-O-R, or CH2=C(CH3)-C(=O)-O-R1 where R, refers to a hydrogen atom, a linear, cyclic or ramified alkyl cluster in C1-C40 eventually susbstituted by a halogen atom, a caprolic alcohol alcoxy, cyano, amino or epoxy cluster:;
At least 0 to 40 % in weight of another monomer b2 chosen from among the monomers polymerized radically such as ethyl, vinyl aromatic or similar polymers.
9. Film according to claims 7 or 8 in which block B has a glass transition
temperature lower than 0°C, an average mass weighing between 40000 and
200000 g/mol and a polymolecularity index between 1.1 and 2.5, preferably
between 1.1 and 2.0.
10. Film according to claims 7 to 9 in which Block A is obtained by
polymerization of a monomer mix A0 comprising of
At least 60 to 100 % in weight of a (meth) acrylic monomer b, having the formula CH2=CH-C(=O)-O-R1 or CH2=C(CH3)-C(=O)-O-R, where R, refers to a hydrogen atom, a linear, cyclic or ramified alkyl cluster in C1-C40 eventually susbstituted by a halogen atom, a caprolic alcohol alcoxy, cyano, amino or epoxy cluster:;
15. At least 0 to 40 % in weight of a monomer, chosen from amongst the
anhydrides such as maleic anhydride or vinyl aromatic monomers such as
styrene or its derivatives, especially alphamethyl styrene.
11. Film according to claims between 7 to 10, in which block A represents
a glass transition temperature higher than 50°C.
12. Film according to claims between 7 to 11, in which I is an organic
cluster having one of the following formulae:
(Formula Removed)
in which:
- Ar refers to a substitued aromatic group,
- Z is a polyfunctional organic radical whose molar weight is greater
than or equal to 14 and
- n is an integer greater than or equal to 2.
14. Film according to claims between 7 to 12 in which the alcoxyamine is
chosen from among the compounds having one of the following formulae :
(Formula Removed)
in which :
- Ar refers to a substitued aromatic group,
- Z is a polyfunctional organic radical whose molar weight is greater than or
equal to 14 and
- n is an integer greater than or equal to 2.
14. Film according to claims 7 to 12, in which T refers to a nitro-oxide
formula
(Formula Removed)
with Ra and Rb referring to identical or different alkyl clusters, having between 1 to 40 carbon atoms, eventually linked to each other so as to form a cycle and eventually substituted by hydroxyl, alcoxyl or amino clusters.
and R, refers to a monovalent group with a molar mass greater than 16g/mol, preferably greater than 30 g/mol.
15. Film according to claim 14 in which nitroxide T corresponds to the
formula:
(Formula Removed)
16. Film according to claims between 1 to 15, in which the methacrylic
(co)polymer used in the manufacture of layers (A) and eventually (C), as well as for t
compoind (Bl) of layer B, consists of 51 to 100% of methyl methacrylate and 0 to
49% of co monomer patterns of unsaturated co polymerisable ethly with methyl
methacrylate.
17. Film according to one of the claims between 1 to 16 in which the same
methacrylic (co) polymer is used for layers A and C.
18. Film according to one of the claims between 1 to 17 in which the
acrylic copolymer has between 80 to 99% in weight of methyl methacrylate and I to
20% of (meth)acrylic acid or corresponding ester with an alkyl group containing Ito 4
carbon atoms.
20. Use according to claim 19 for molding technique with simultaneous
insertion of film.
21. The film is used to coat a substrate as defined in one of the claims
between 1 to 20.
22. The film is used according to claim 21 in which the substrate is a
thermoplastic resin
23. The film is used according to claim 21 in which the substrate is a
thermosetting resin.
24. The film is used according to claim 21 in which the substrate is made
of wood, cork wood, a cellulosic material, steel, alumunium, wood coated with a layer
of melamine, melamine-formol or melamine-phenol resin.
25. The film is used according to one of the claims between 19 to 24 in
which and adhesive agent is placed between the substrate and the acrylic film.
26. Acrylic multilayered film, substantially as hereinbefore described with
reference to the foregoing examples.