CA2092620A1 - Composite articles made of flame-resistant polymerizates - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
The invention relates to objects made of a mixture comprising 70 to 99.9 parts by weight of a polymerizate A, containing 20 to 100% by weight of styrene units with 0.1 to 30 parts by weight of a flame retardant B, which is compatible with A, as the core material, which is provided with a coating of a poly(meth)acrylate C, which is compatible with the mixture made of A and B and which contains 10 to 100% by weight of monomers of the formula I

where R1 stands for hydrogen or methyl and R2 stands for an optionally alkyl-substituted cycloalkyl group having 5 to 8 carbon atoms or for a non-aromatic, ring carbon containing heterocycle having 4 to 12 rings atoms and at least 2 heteroatoms X = O. S, NH, where the heteroatoms may not stand next to each other, wherein the polymerizate A
exhibits less than 10% by weight of polar monomers selected from the group (meth)acrylonitrile, maleic acid anhydride and maleic acid imides.

Description

TITLE OF THE INVENTION:

COMPOSITE ARTICLES MADE OF FLAME-RESISTANT POLYMERIZATES

BACKGROUND OF THE INVENTION
Field of the Invention:
The invention relates to styrene containing polymerizates with good flame resistance, and composite articles made thereof. The flame resistant polymerizate mixture is surprisingly compatible with a poly(meth)acrylate coating, so that the article may be both weather resistant and exhibit high transparency.

Discussion of the Background:
As a rule, different polymer species are considered to be incompatible. That is, different polymer species generally do not mix to form a homogeneous phase, even down to the smallest percentages of a component. Such a mixture would be characterized by total miscibility of the components.
Certain narrow exceptions are known. Fsr instance, under some conditions, copolymerizates comprising styrene and maleic acid anhydride or styrene and acrylonitrile are compatible with polymethyl methacrylate (PMMA). The conditions are described in DE-A 20 24 940, where the improved functional properties of these molding compositions are emphasized. Copolymerization comprising ' ' '- ~' ' ' ' ,' '':. ' : ~
, o styrene and monomers containing hydroxyl groups, which enable the formation of hydrogen bonds, are also compatible in specific proportions with polymethacrylates. Examples include copolymarizates comprising styrene and p-~2-hydroxylhexafluoro-isopropyl)styrene (B.I. Min and E.N. Pierce, Organic Coatings and Plastics Chemistry 45, pages 58 to 64, 1981) and copolymerizates comprising styrene and allyl alcohol (F. Cangelosi and M.T. Shaw, Polymer Preprints, Am. Chem. Soc. Div. Polym. Chem. 24, pages 258, 259, 1983.
More recent studies concerning styrene-containing "polymer blends" and their possible application are reported by L.M. Robeson in Polym. Eng. Sci. 24 (8), pages 587 to 597 (1984). Polystyrene and other styrene-containing polymerizates are still considered to be incompatible with PMMA. Similarly, other polymethacrylates and polyacrylates are incompatible with polystyrene. This applies, for example, to polybutyl methacrylate, polyisobutyl methacrylatP, polyneopentyl methacrylate, polyhexyl methacrylate and many others (cf. to this end also R.H. Somani and M.T. Shaw~ Macromolecules 14, pages 1549 to 1554, 1981).
Nechanical mixtures of polymerizates ("polyblends") have in specific cases and in specific fields of the plastic industry resulted in plastic products with improved properties (cf. Kirk-Othmer, 3rd. ed. vol~ 18, page~ 443 ~ '~ ` , : ' ' , , to 478, J. Wiley, 1982). The physical properties of these polyblends usually represent a compromise, meaning essentially that there may be only some improvement over the properties of the individual polymerizates. In any event, multiphase polymer blends have gained a disproportionately greater commercial significance than the compatible mixtures (cf. Kirk-Othmer, loc. cit., page 449).
EP-A 268 Q40 (corresponding to U.S. Pat. Nos.
4,898,912 and 5,047,481) describes compatible polymer blends comprising a first polymerizate component containing -~ a cyclohexyl~meth)acrylate as the monomer, and a second polymerizate component containing styrene as the monomer.
The cited polymer blends are transparent, exhibit a uniform glass transition temperature and a lower critical solution 15 temperature (LCST; see D~-A 34 36 476 and DE-A 34 36 477).
These polymer blends are used preferably as extruded or injection molded articles, data storage plates, optical gradient fibers, protective thermotropic glazing or dispersion films.
In US 4,906,699, an impact modifier for plastics i5 described. The composition contains a phase~separated elastomer which exhibits a glass transition temperature < 10C, and a grafted copolymerizate comprising methyl methacrylate and (meth)acrylic acid esters, which contain optionally substituted cycloalkyl units as ester substituents.

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~3~) In EP-A 451 809, compatible polymer blends comprising a first polymer component having cyclopentyl(meth)acrylate as the monomer, and a second polymer component, having styrene as the monomer are described. Industrial applications are taught.
EP-A 455 272 describes articles which are formed from a polymer containing styrene as the monomer. The article is provided with a coating comprising a polymer containing cyclohexyl(meth)acrylate as the monomer. The polymerizate forming the coating may or may not contain an ultraviolet absorber, which can also be polymerized. Contemplated articles are, for example, injection molded or extruded articles, data storage plates or optical gradient fibers.
Moving now into a different field, flame resistant polymerizates are needed for a number of applications~
These applications include housing and airplane construction, the automobile sector, and machine housing construction~ In these cases especially, flame resistant polymerizates are desired that simultaneously exhibit high transparency and weathering resistance. Such a composition might include polymers which have a high percentage of aromatic structures, and have a low percentage of readily oxidizable subgroups/ and which would exhibit a relatively high flame resistance (cf. to this end Kirk Othmer, Encyclopedia of Chemical Technology, 3rd. ed. vol. 10, pages 348 - 355, J. Wiley, 1980).

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Febr.26~1993 ~C~ }-- Aromatic poly~midas have excellent flame resistance, however they show poor weathering resistance and poor thermoplastic processability. styrene-containing polymerizates such as polystyrene, impact modified polystyrenes or acrylonitrile-butadiene-styrene-terpolymerizates (ABS), which are often used for the aforementioned applications, also exhibit a high percentage of aromatic structures, but have to be stabilized with flame retardants owing to their high percentage of readily oxidizable groups (Kirk-Othmer, loc. cit., page 350).
Normally up to 30% by wt. of a flame retardant are added to the styrene-containing polymerizate (Kirk-Othmer, loc.
cit., page 382). An addition of flame retardant in this magnitude chanqes substantially the polymerizate properties, whereby in many cases the flame retardant has to be custom-made. The aforementioned styrene-containing polymerizates are highly unstable to the weathering-induced action of light, in particular ultraviolet radiation, which manifests itself in an undesired strong yellowing.

SUMMARY OF THE INVENTION
The present invention surprisingly solves the problem of manufacturing styrene-containing polymerizates with good flame resistance and good weathering resistance. The invention provides articles made of a mixture comprising 70 25 to 99.9 parts by weight o~ a polymerizate A, containing 20 - , ~ . . ~

to 100% by weight o~ styrene and 0 to ~0% by weight of other monomers that can be copolymerized with styrene, and 0.1 to 30 parts by weight of a flame rstardant B.
An important characteristic of the mixture is that polymerizate A is compatible with flame retardant B. The mixture A and B provides the core material for the final article, the core being coated with a coating of a poly(meth)acrylate C. Poly(meth)acrylate C, which is compatible with the mixture made of A and B, contains 10 to 100% by weight of monomers of the formula I
CH2 = C ~ 0 - R2 (I) wherein Rl stands for hydrogen or methyl and ~ stands for an optionally alkyl-substituted cycloalkyl group having 5 to 8 carbon atoms or for a non-aromatic, ring carbon-containing heterocycle having 4 to 12 rings atoms and at least 2 heteroatoms X = 0, S, NH, where the heteroatoms may not be adjacent. Polystyrene A can contain up to 10% by weight, pre~erably no more than 5%, even more preferably less than 1%, of polar monomers selected from the group (meth)-acxylonitrile, maleic acid anhydride and maleic acid imides. Furthermore, weathering resistant objects are envisioned wherein the poly(meth)acrylate C
contains 0.1 to 20% by weight, preferably 1 to 18%, more preferably 3 to 15, still more preferably 5 to 12% of ultraviolet absorber, which may or may not be polymerized.

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Accordingly, one object of the present invention is to provide a composite that has surprisingly good flame resistance. The composite is formed of a core substrate, comprising polymerizate A and flame retardant B, with a cover layer comprising poly(meth)acrylate C. Despite poly(meth)acrylate coating, the flame resistance of the composite corresponds to the flame resistance of the core.
Another object is to provide a more effective weathering protection of the substrate, in particular against ultraviolet-induced negative effects. The substrate may contain ultraviolet unstable polymerizates A
such as polystyrenes or mixtures of polystyrenes and polyphenylene ethers. The optical properties would be expected to degenerate quickly over time. In the present invention, the cover layer comprising polymerizate C is provided with ultraviolet absorbers (which can be polymerized or mixed in low molecular form). This is especially important with transparent substrate materials such as transparent, flame-resistant polystyrene.
A further object of the present invention is to provide a composite having improved light transmission.
When formed as a plate wherein the substrate exhibits a higher refraction index than the cover layer (e.g., poly(meth)acrylate layers on flame resistant polystyrene), the composite has lmproved light transmission with respect to the uncoated substrate. This is highly unexpected.

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An especially interesting application i~ the use of these composites in multi-coated hollow-core multi-panes.
They are used, for example, in greenhouses for glazing. In the case of multiple coatings the light transmission can be significantly improved (cf. to this and, for example, German utility model G 85 14 365.0).
Still further, the present invention provides a scratch and corrosion-resistant composite. The core substrate materials (such as polystyrene) have a low scratch resistance and/or low corrosion resistance. The composite has better scratch resistance and modified corrosion properties, provided by the poly(meth)acrylate C.
Additionally, a major problem with previous manufacturing processes of plastic composites is the disposal of scraps. The scraps are heterogeneously coated and thus cannot readily be reused. This problem is avoided in the present invention, since plastic scraps can be freely mixed in with other materials, owing to the good compatibility of the various ingredients.
Polymerizate A, flame retardant B and poly(meth)-acrylate C have clearly different compositions, as set forth herein. According to the state of the art, complete compatibility in the present ternary system is not expected. In spite o~ this, the compatibility of mixtures formed by A, B and C is so good that in some cases there is no separation at 200C and above.

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DESCRIPTION OF THE PREFERRED EMB~DIMENTS
Polymerizate A
The styrene content of polymerizate A is at least 20%
by weight, preferably at leas~ 50% by weight, more preferably at leas~ 90% by weight, even more preferably at least 99% by weigh, and still more preferably at least 99.9% by weight. The styrene in polymerizate A can be substituted by p-methyl styrene at a few % by weight, e.g.
10~ by weight. Furthermore, to a certain degree an exchange of the styrene with other alkyl-substituted styrenes is possible. In particular, Cl-C4 or more particularly Cl or C4 substituted styrenes, such as m-methyl styrene or p-tert-butyl-styrene, may be used. Similarly, styrene can be partially replaced by esters of acrylic acid and of the methacrylic acid. Particularly preferred are esters of Cl to Cla alcohols, more preferably by alcohols having 1 to 8 carbon atoms. Furthermore, the styrene can be replaced in subordinate quantities by other vinyl compounds, in particular vinyl esters, such as vinyl acetates and vinyl propionate. Although th~ polymerization component A can be extensively modified with other hydrophobic vinyl compounds, the content of very polar monomers, such as (meth)acrylonitrile, maleic acid anhydride, maleic acid imides, p-(2-hydroxylhexa-fluoroisopropyl)styrene or allyl alcohol, is very limited.These polar monomers are preferably present below 10% by , .

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weight, more preferably below 5% by weight, of polystyrene A. Especially preferred are such polymerizates A, which contain less than 0.1% by weight of these polar monomers, most preferably 0% by weight. Furthermore, toughened polystyrenes such as styrene-butadiene-copolymerizates, elastomer-modified copolymers made of styrene and methyl methacrylate or other high impact polystyrene (HIPS) types can be used, for example, as polymerizate A (cf. to this end Kirk-Othmar, Encyclopedia of Chemical Technology, 3rd.
ed., vol. 21, pages 801 to 847, J. ~iley, 1983).
Preferably the aforementioned polymeriæates A are transparent, such as polystyrene or styrene-butadiene-styrenes (SBS)-triblock copolymers.

Flame retardant B
Flame retardants B can be divided into three main classes: inorganic compounds, organic halogen-containing compounds and phosphorous-containing compounds. These flame retardants are per se known in the art, as disclosed in Kirk-Othmer, 3rd ed. vol. 10, pages 348 to 419, J.
Wiley, 1980, hereby incorporated by reference. Any flame retardant disclosed therein may be used in the present invention. Preferred retardants B for styrene-containing polymerizates A include combinations of antimony trioxide and halogen-containing additives, aIuminum trihydrate, hexabromocyclododecane, tris-(2-chloroethyl)phosphate, , . :
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tris-(1,3-dichloro-2-propyl)phosphate or tris-(2,3-dibromo-1-propyl)phosphateO Especially preferred with transparent styrene-containing polymerizates A are flame retardants B which do not significantly reduce the light transmission following mixing, such as the combination of polystyrene (A~ and hexabromocyclododecane (B). The flame r~tardants B are incorporated into the polymerizate A, for example, by means of melt mixing in the kneader or extruder, by coating or by means of copolymerization (methods per sa ~nown in the art; cf.
Kirk-Othmer, loc. cit., page 349).

The polymerizate C
The coating of poly(meth)acrylate C, based on formula (I) above is as menti~ned previously, surprisingly compatible with the mixture of A and B.
Preferably used as monomers for (I) are cyclohexylmethacrylate, cyclohexylacrylate, cyclopentylmethacrylate and/or 2,2-dimethyl-1,3-dioxolane-4-yl-methyl-methacrylate. Most preferable are cyclohexylmethacrylate and cyclohexylacrylate.
In the case of copolymerizates, comonomers in the polymerizate C can be present in proportions ranging from 0 to 90% by weight, preferably from 10 to 80% by weight, more preferably from 30 to 70% by weight, most preferably from 40 to 60% by weight. Suitable comonomers are acrylic- or , .

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methacrylic acid esters, such as methyl methacrylate.
Preferable esters are those with non-alicyclic alcohols having l to 12 carbon atoms. More preferable are those with alkanols. The ratio of the monomers of formula I to the content of polymerizate C ranges as a rule from ~00 to 10% by weight, preferably from 90 to 20% by weight, even more preferably from 70 to 30% by weight, and still more preferably from 60 to 40% by weight. Pre~erably the polymerizates C are copolymerizates comprising 50 to 75% by weight of methyl methacrylate, 20 to 50% by weight of `` cyclohexylmethacrylate, 0.5 to 5% by weight acrylic acid esters of cyclic and/or non-alicyclic alcohols having 1 to 12 carbon atoms. Optionally, other methacrylic acid esters of non-alicyclic alcohols having 3 to 18 carbon atoms may be used, up to 20% by weight.
The polymerizates C can also contain flame retardants and may or may not be impact modified with elastomer Febr.26~1993 polymerizates ~C~ hases. Impact modified tmeth)acrylate ~ are manufactured by methods known in the art (for example, DE-A
38 42 796).
Preferably the polymerizate C should contain 0.1 to 20% by weight (based on polymerizate C) of at least one ultraviolet absorber, which is prefarably copolymerized, in expedient distribution. Usable ultraviolet absorbers are those known per se in the art. For example, see Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd ed., : : :

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vol. 23, pages 615 to 627, J. Wiley 1983; R. Gachter and H.
Muller, Handbook of Plastic Additives, pages 90 to 143, Carl Hanser, 1979, Ullmann's Encyclopadie der Technischen Chemie, vol. 15, pages 256 to 260, 4th ed., Verlag Chemie.
These references are hereby incorporated by reference.

Preparation of polymerizates A and C
The polymerizates A and C can be prepared according to the known rules of polymerization a~d according to known methods.
~ 10 The polymerizates of type A can be prepared, for example, according to Houben-Weyl, Methoden der Organischen Chemie, 4th ed., vol. XIVt1, pages 761 to 841, Georg Thieme Verlag, 1961. Radical polymerization or ionic polymerization processes can be used. They are also commercially available in the suitable form. The average molecular weight (Mw; weight average) of the polymerizates A used according to the inven~ion are as a rule above 3,000, preferably starting from or above 5,000, more preferably in the range of 5,000 to 106, still more preferably between 2 x 104 and 5 x 105 Dalton (determined by light scattering). At the same time it is stressed that the average molecular weights (Mw) do not, by itself, seem to have the most critical effect on the suitability of the polymerizates ~. This applies both to the homopolymerizates and also to the copolymerizates of types A and C.

2~o ~14-The tacticity of the polymers is important to a certain degree for the compatibility of polymerizate A and polymerizate C. As a rule, especially preferred is a polymerizate C with a low percentage of isotactic triads (as obtained, for example, through radical polymerization) with respect to polymerizates with high isotactic content, as generated by specific ionic polymerization.
Homo~ or copolymerizates C are prepared according to known methods (cf. to this end H. ~auch-Puntigam, Th.
Volker, Acrylic and methacrylic compounds, Springer Verlag, `` 1967). A preparation by means of anionic or group transfer polymerization is possible (see to this end O.W. Webster et al., J. Am. Chem. Soc., vol. 105, 5706 (1983)), but the radical polymerization is still the preferred method o~
preparation. The average molecular weights (Mw) of polymerizates C are as a rule above 3,000, pr~ferably above 5,000, more preferably in the range of 104 to 106, even more preferably in the range of 2 x 104 to 5 x 105, still more preferably in the range of 2 x 104 to 3 x 105 Dalton (determined by light scattering). When selecting the monomer components, which are to be added as the comonomers for the polymerizate C, caution must be taken that the glass transition temperature of the resulting polymerizate C does not have a limiting effect on the commercial application.

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2 ~) The coatlnq of the mixture formed by A and B with polymerizate C.
The poly(meth)acrylates C according to the present invention are excellent coatings for the substrate materials comprising mixtures of polymerizate A and flame retardant B, due to their good adhesion. The coatings form polymer blends, in accordance with the criteria of the uniform glass transition temperature or the "optical method" (i.e., clarity of a film poured from a homogeneous solution of the polymer mixture, cf. ~randrup, Immergut, Polymer Handbook, 2nd ed. III; page 211, J. Wiley, 1975), which are compatible with the mixtures formed by A and B~
The occurrence of the lower critical solution temperature (LCST) is used as another test for the miscibility (cf. to this end US Patent Nos. 3,253,060 and 3,458,291). The occurrence of the LCST is based on the following behavior:
upon heating a clear, homogeneous polymer blend, the composition separates into phases and, in so doing, becomes cloudy to turbid. According to what is known from the literature, this behavior is proof for the fact that the original polymer blend had comprised a single homogeneous phase in thermodynamic equilibrium.
The polymer blends, comprising A, B, and C, are surprisingly homogenous and exhibit separating temperatures of > 120C, preferably > 150C. The turbidity point (turbidity temperature = phase transition from homogeneous .

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to heterogeneous) is determined by experiment, for example, on the Kofler heating bench (Chem. Ing. Technik, 1950, page 289).
Tha cover layer, comprising poly(meth)acrylate C, exhibits excellent adhesion on the substrate, comprising polymerizate A and flame retardant B, due to its compatibility. The cover layer C is applied by otherwise known methods, e.g., by coextrusion or paint film, in layer thicknesses ranging from 1 to 500 ~m, preferably from 1 to 200 ~m, more particularly from 1 up to about 1oo ~m.
Multiple coatings may be applied, as mentioned previously, and more than one side of the core A ~ B may be coated.
With the extrusion method, for example, known multi-component slit dies are used. The extrusion takes place, for example, at temperatures ranging from 150 to 3000C. With the paint film method, for example, halogenated solvents such as chloroform or halogen-free solvents such as l-methoxypropanol-2 can be used.
Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustxation only and are not intended to be limiting unless otherwise specified.

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The flame resistance is determined in accordance with DIN 4102. The weathering resistance is determined in the xenotest in accordance with DIN 53 387. The light transmission TD65 is determined in accordance with DIN
5033/5036.

Synthesis of polY(methlacrylate C
The monomers are polymerized in the water bath, for example, with the addition of 0.4 parts by weight tbased on the monomers) of tert-butyl perpivalate, 0.1 parts by weight of 2,2'-azobisisobutyronitrile and 0.4 parts by weight of dilauroyl peroxide as polymerization initiators and 0.5 parts by weight of dodecylmercaptan as molecular weight controller in the film bubble for 3 hours a 55C and 16 hours at 50OC. For the final polymerization the mixture is tempered in the oven at 110C for threa hours. The polymerizate is colorless and transparent. The average molecular weights (Mw) range from 8 x 104 to 1.2 x 105 Dalton depending on the monomer composition. Finally the polymerizates prepared in such a manner are ground.

Example 1 Coating of a flame resistant polystyrene - hollow core double pane with poly(meth)acrylate C

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A monomer mixture comprising methyl methacryla~e, cyclohexyl methacrylate, methacrylate and 2-(2'-hydroxyphenyl)-5- methacrylamido-benzotriazole (HPMAB) was polymerized according to the above instructions and then ground. The composition of the poly(math)acrylate C is:
58~ by weight methyl methacrylate 35~ by weight cyclohexyl methacrylate 5% by weight HPMAB
2% by weight methylacrylate The polymerizate C is ground and pelletized following extrusion and monomer degassing.
The formulation obtained by such a method is applied in coextrusion in an extrusion tool by means of a multi-channel die on the hollow-core double panes (SnP), comprising a fire proof polystyrene (Polystyrol. 158 KWU~, BASF, Bl-flame resistance in accordance with DIN 4102).

The thickness of the coextrusion layer ranges from 20 Febr.26,1993 ~C~ ( ~ 100 ~, the thickness over the flanges being generally at the lower limit.

Example 2 Weathering of the hollow-core double panes coated according to Example 1 Hollow-core double panes coated according to Example 1 show after 5,000 hours of the xeno test no significant ~' ' .' '.

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yellowing or turbidity. Uncoated substrate material has already a noticeable yellow tinge and is dull after 500 hours.

Example 3 Flame resistance test using the hollow core double panes coated according to Example 1.
Hollow core double panes coa~ed according to Example 1 exhibit Bl flame resistance according to DIN ~102, just like the uncoated substrate-hollow core double panes.

Exam~le 4 Transparency of the hollow core double panes coated according to Example 1 The degree of transmission TD65/lo at the upper flange of the coated hollow core double pane is according to DIN
15 5033/5036 90.6% with an upper flange thickness o~ 1.8 mm.
In comparison, the TD6~/to at the upper flange of an uncoated hollow core double pane is 90.5%, of course with a decreased upper flange thickness of 1.5 mm.

Example 5 Reprocessing potential of wastes of the hollow core double panes coated according to Example 1 Polystyrene is mixed to the melt at 20% by weight with ground pane scraps of the coatad hollow core double pane , :
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sections and pelletized. This mixture is extruded into a hollow core double pan~ and coated according to Example 1.
The properties of the hollow core double panes obtained thus correspond to those coated hollow core double panes obtained according to Example 1.
Obviously, numerous modifications and variations of the present invantion are possible in light of the above teachings. It is therefor to he understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

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Claims (20)

1. A composite article including a first layer comprising 70 to 99.9 parts by weight of a polymerizate A
and 0.1 to 30 parts by weight of a flame retardant B, and a second layer comprising a poly(meth)acrylate C, said polymerizate A containing 20 to 100% by weight of styrene monomer units, said poly(meth)acrylate C containing 10 to 100% by weight of monomers of formula (I):

(1) wherein R1 is selected from the group consisting of hydrogen and methyl;
R2 is selected from the group consisting of cycloalkyl groups having 5 to 8 carbon atoms, alkyl-substituted cycloalkyl groups having 5 to 8 carbon atoms, and non-aromatic, ring carbon-containing heterocycles having 4 to 12 rings atoms and at least 2 heteroatoms selected from at least one of the group consisting of O, S, and NH, wherein the heteroatoms are non-adjacent; and wherein A, B, and C are compatible.

2. The composite article according to Claim 1, wherein polymerizate A includes from 0.01% to 10% by weight of monomers selected from the group consisting of (meth)acrylonitrile, maleic acid anhdydride, and maleic acid imides.

3. Weathering resistant articles comprising the composite according to Claim 1, wherein the poly(meth)acrylate C contains 0.1 to 20% by weight, based on C, of at least one ultraviolet absorber.

4. The article according to Claim 3, wherein at least one ultraviolet absorber is polymerized.

5. The article according to Claim 3, made by injection molding.

6. The article according to Claim 3, made by extrusion.

7. A hollow core multi-pane comprising the article according to Claim 1.

8. A hollow core multi-pane comprising the article according to Claim 4.

9. A hollow-core multi-pane comprising the article of Claim 6.

10. The article according to Claim 1, wherein said second layer has a thickness from l to 200 µm.

11. The article according to Claim 1, wherein said second layer contains a flame retardant.

12. The article according to Claim 1, having at least a third layer of poly(meth)acrylate C.

13. The article according to Claim 1, wherein A, B, and C together exhibit a separation temperature of at least 120°C.

14. The article according to Claim 1 wherein poly(meth)acrylate C is obtained through radical polymerization.

15. The article according to Claim 1, wherein poly(meth)acrylate C is a copolymerizate comprising 50 to 75% by weight methyl methacrylate, 20 to 50% by weight of cyclohexylmethacrylate, and 0.5 to 50% by weight of acrylic acid esters of C1-C12 alcohols.

16. The article according to Claim 1, wherein flame retardant B is hexabromocyclodecane.

17. The article acccording to Claim 1, made by a process comprising preparing at least a first composite according to Claim 1, including at least one step of generating scraps of said first composite, and then adding the scraps to a composition comprising polymerizate A or poly(meth)acrylate C, and then preparing said article from the composition including the added scraps.

18. An article comprising a core with at least one coating, wherein said core is a compatible mixture of:
70 to 99.9 parts by weight of a polymerizate A, said polymerizate A comprising 20 to 100% by weight of styrene monomer units and 0.1 to 30 parts by weight of a flame retardant B; and wherein said at least one coating is a poly(meth)acrylate C containing 10 to 100% by weight of monomers of formula (I):
(I) wherein R1 is selected from the group consisting of hydrogen and methyl;
R2 is selected from the group consisting of cycloalkyl groups having 5 to 8 carbon atoms, alkyl-substituted cycloalkyl groups having 5 to 8 carbon atoms, and non-aromatic, ring carbon-containing heterocycles having 4 to 12 rings atoms and at least 2 heteroatoms selected from at least one of the group consisting of O, S, and NH, wherein the heteroatoms are non-adjacent; and wherein A, B, and C are compatible.

19. The article according to Claim 17, wherein said coating has a thickness from about 1 to 200 µm.

20. A homogeneous polymer blend comprising polymerizate A, flame retardant B, and poly(meth)acrylate C
as claimed in Claim 1, which exhibits a separation temperature greater than or equal to 120°C.