Multilayer acrylic film with improved optical and mechanical properties
Multilayer acrylic film comprising: a layer (A) made from a thermoplastic acrylic composition comprising from 75 to 95% of a metliacrylic (co)polymer containing mostly methyl methacrylate units and from 5 to 25% of an impact modifier a layer (B) made from either a composition comprising a methacrylic (co)polymer and an impact modifying compound, or a composition prepared by sequential polymerization in aqueous emulsion of acrylate-based monomer systems, or a composition comprising, a block copolymer, and a layer (C) made from a thermoplastic acrylic composition comprising from 75 to 95% of a methacrylic (co)polymer containing mostly methyl methacrylate units and from 5 to 25% of an impact modifier. Use of the film for coating a substrate (thermoplastic resin, thermosetting resin, etc.).
1 . Multilayer acrylic film having a thickness between 40 and 300 μm, comprising in this order:
a layer A made from a thermoplastic acrylic composition (A) comprising from 75 to 95% of a methacrylic (co)polymer containing mostly methyl methacrylate units and from 5 to 25% of an impact modifier;
a layer B1 made from a composition (B1) comprising from 10 to 50% of a methacrylic (co)polymer containing mostly methyl methacrylate units and from 50 to 90% of an impact modifying compound;
a layer C made from a thermoplastic acrylic composition (A) comprising from 75 to 95% of a methacrylic (co)polymer containing mostly methyl methacrylate units and from 5 to 25% of an impact modifier;
the layers A, B1 and C being joined together in their respective contact zones and the ratio of the thickness of layer B1 to the total thickness of the multilayer film being between 85 and 99%, preferably between 88 and 95%, and more preferably between 88 and 92%.
2 . Film according to claim 1 , characterized in that the ratio of the thickness of layer B1 to the total thickness of the multilayer film is between 88 and 95%.
3 . Film according to claim 1 , characterized in that composition (B1) comprises from 30 to 50% of a methacrylic (co)polymer, and from 50 to 70% of an impact modifier.
4 . Film according to claim 1 , characterized in that the impact modifier comprises a polymeric substance having a multilayer structure.
5 . Film according to claim 4 , characterized in that the impact modifier has a “soft-hard” morphology.
6 . (canceled)
7 . Multilayer acrylic film having a thickness between 40 and 300 μm, comprising in this order:
a layer A made from a thermoplastic acrylic composition (A) comprising from 75 to 95% of a methacrylic (co)polymer containing mostly methyl methacrylate units and fi-on 5 to 25% of an impact modifier:
a layer B2 made from a composition (B2) that can be obtained by the method comprising:
1) preparation by sequential polymerization in aqueous emulsion:
a) of a first copolymer, by reaction of a system of monomers comprising:
from 75 to 99.8% of at least one acrylate of an alkyl radical comprising from 1 to 8 carbon atoms, and
from 0.1 to 5% of a crosslinking agent selected from the polyacrylic and polymethacrylic esters of polyols, the di- or trivinyl benzenes or the vinyl esters, and
from 0.1 to 20% of at least one grafting agent selected from the allylic, methallylic or crotonic esters of an α,β-unsaturated monocarboxylic or dicarboxylic acid; then
b) of a second copolymer, in the presence of the aqueous system resulting from stage a), by reaction of a system of monomers comprising:
from 10 to 90% of at least one first acrylate of an alkyl radical containing from 1 to 8 carbon atoms, and
from 9 to 89.9% of at least one second acrylate of an alkyl radical containing from 1 to 8 carbon atoms, different from the first one, and
0.1 to 1% of at least one crafting agent selected from the allylic, methallylic or crotonic esters of an α,β-unsaturated monocarboxylic or dicarboxylic acid; then
c) of a third copolymer, in the presence of the aqueous system resulting from stage b), by reaction of a system of monomers comprising:
from 5 to 40% of at least one acrylate of an alkyl radical containing from 1 to 8 carbon atoms, and
from 60 to 95% of at least one second acrylate of an alkyl radical containing from 1 to 8 carbon atoms, different from the first one; then
d) of a fourth polymer, in the presence of the aqueous system resulting from stage c), by reaction of a system of monomers comprising:
from 80 to 100% of at least one acrylate of an alkyl radical containing from 1 to 8 carbon atoms, and
from 0 to 20% of at least one second acrylate of an alkyl radical containing from 1 to 8 carbon atoms, different from the first one;
it being stipulated that:
the weight of the copolymer obtained in stage a) represents from 10 to 75%, and
the total weight of the copolymers introduced in stages b), c) and d) represents from 25 to 90%, relative to the total weight of the composition comprising the 4 copolymers obtained after stage d); then
2) drying of the aqueous emulsion thus obtained; then
3) optionally, granulation of the product thus dried;
optionally a layer C made from a thermoplastic acrylic composition (C) comprising from 75 to 95% of a methacrylic (co)polymer containing mostly methyl methacrylate units and from 5 to 25% of an impact modifier;
the layers A, B2 and optionally C being joined together in their respective contact zones.
8 . Film according to claim 7 , characterized in that the ratio of the thickness of layer B2 to the total thickness of the multilayer film is between 85 and 99%,.
9 . Multilayer acrylic film having a thickness between 40 and 300 μm, comprising in this order:
a layer A made from a thermoplastic acrylic composition (A) comprising from 75 to 95% of a methiacrylic (co)polymer containing mostly methyl methacrylate units and from 5 to 25% of an impact modifier:
a layer B3 made from a composition (B3) comprising from 0 to 5 wt % of at least one polymer A and from 95 to 100 wt % of at least one block copolymer of formula B(-A) n composed of a block B and n blocks A obtained by radical polymerization controlled by means of an alkoxyamine of formula I(-T) n in which I denotes a multivalent group, T denotes a nitroxide and n denotes an integer greater than or equal to 2;
optionally a layer C made from a thermoplastic acrylic composition (A) comprising from 75 to 95% of a methacrylic (co)polyiner containing mostly methyl methacrylate units and from 5 to 25% of an impact modifier;
layers A, B3 and optionally C being joined together in their respective contact zones.
10 . Film according to claim 9 , characterized in that the ratio of the thickness of layer B3 to the total thickness of the multilayer film is between 85 and 99%.
11 . Film according to claim 10 , characterized in that block B is obtained by polymerization of a monomer mixture B 0 comprising:
from 60 to 100 wt % of at least one (meth)acrylic monomer b 1 of fornula CH 2 ═CH—C(═O)—O—R 1 or CH 2 ═C(CH 3 )—C(═O)—O—R 1 where R 1 denotes a hydrogen atom, a linear, cyclic or branched C 1 -C 40 alkyl group optionally substituted by a halogen atom, a hydroxy, alkoxy, cyano, amino or epoxy group;
from 0 to 40 wt % of at least one other monomer b 2 selected from monomers that are polymerizable by the radical route such as ethylenic, vinylaromatic and similar monomers.
12 . Film according to claim 9 , characterized in that block B has a glass transition temperature below 0° C. a weight-average molecular weight between 40000 and 200000 g/mol and an index of polymolecularity between 1.1 and 2.5,
13 . Film according to claim 9 , characterized in that block A is obtained by the polymerization of a monomer mixture A 0 comprising:
from 60 to 100 wt % of at least one (meth)acrylic monomer a 1 of formula CH 2 ═CH—C(═O)—O—R 1 or CH 2 ═C(CH 3 )—C(═O)—O—R 1 where R 1 denotes a hydrogen atom, a lineal-, cyclic or branched C 1 -C 40 alkyl group optionally substituted by a halogen atom, a hydroxy, alkoxy, cyano, amino or epoxy group;
from 0 to 40 wt % of at least one monomer a 2 selected from the anhydrides such as maleic anhydride or vinylaromatic monomers such as styrene or its derivatives, in particular alpha-methylstyrene.
14 . Film according to claim 9 , characterized in that block A has a glass transition temperature above 50° C.
15 . Film according to claim 9 , characterized in that I is an organic group conforming to one of the following formula:
in which:
Ar denotes a substituted aromatic group,
Z is a polyfunctional organic radical with molar mass greater than or equal to 14, and
n is an integer greater than or equal to 2.
16 . Film according to claim 9 , characterized in that the alkoxyamine is selected from the compounds conforming to one of the following formula:
in which:
Ar denotes a substituted aromatic group,
Z is a polyfunctional organic radical with molar mass greater than or equal to 14, and
n is an integer greater than or equal to 2.
17 . Film according to claim 9 , in which T denotes a nitroxide of formula
with R a and R b denoting identical or different alkyl groups having from 1 to 40 carbon atoms, optionally joined together so as to form a ring and optionally substituted by hydroxy, alkoxy or amino groups,
and R L denoting a monovalent group of molar mass greater than 16 g/mol,
18 . Film according to claim 17 , characterized in that the nitroxide T conforms to the formula:
19 . Film according to claim 1 , characterized in that the methacrylic (co)polymer used for the manufacture of layers (A) and optionally (C), as well as for composition (B1) of layer B, comprises from 51 to 100% of methyl methacrylate units and from 0 to 49% of ethylenically unsaturated comonomer units copolymerizable with methyl methacrylate.
20 . Film according to claim 1 , characterized in that the same methacrylic (co)polymer is used for layers A and C.
21 . Film according to claim 1 , characterized in that the acrylic copolymer comprises from 80 to 99 wt % of methyl methacrylate units and from 1 to 20% of (meth)acrylic acid or of the corresponding ester with an alkyl radical containing from 1 to 4 carbon atoms.
22 . An in-mould decorated article comprising a thermoplastic resin and the film of claim 1 .
23 . (canceled)
24 . A coated substrate comprising a substrate coated with the film of claim 1 .
25 . The coated substrate according to claim 24 , characterized in that the substrate is a thermoplastic resin.
26 . The coated substrate according to claim 24 , characterized in that the substrate is a thermosetting resin.
27 . The coated substrate according to claim 24 , characterized in that the substrate is of wood, compreg, a cellulosic material, steel, aluminium, wood coated with a layer of melamine, melamine-formaldehyde or melamine-phenolic resin.
28 . The coated substrate according to claim 24 characterized in that an adhesive is arranged between the substrate and the film.
29 . The multiplayer acrylic film of claim 1 , having a thickness between 70 and 100 μm.
30 . The multiplayer acrylic film of claim 7 , having a thickness between 70 and 100 μm.
31 . The multiplayer acrylic film of claim 9 , having a thickness between 70 and 100 μm.
32 . The multiplayer film of claim 1 , wherein the ration of the thickness of layer B1 to the total thickness of the multiplayer film is between 88 and 92%.
33 . Film according to claim 12 , characterized in that block B has an index of polymolecularity between 1.1 and 2.0.
34 . Film according to claim 9 wherein R L denotes a monovalent group of molar mass greater than 30 g/mol.