JP2009517538A - Tulipaline copolymer - Google Patents

Abstract

  Copolymers comprising structural units derived from α-methylene-γ-butyrolactone, styrene, methyl methacrylate, and optionally acrylonitrile can be used as a protective layer in multilayer articles comprising UV sensitive substrate materials. The multilayer article may include a silicone hard coat.

Description

(background)
The present invention relates generally to copolymers of α-methylene-γ-butyrolactone with methyl methacrylate, styrene, and optionally acrylonitrile, and articles made therefrom.

  Tulipalin, a polymer made from α-methylene-γ-butyrolactone (MBL), has been known for over 50 years (US 2,624,723).

MBL is called tulipaline because it is present in white tulips at a relatively high concentration. The homopolymer is a brittle glassy material with a glass transition temperature (T _g ) of 195 ° C. (Macromolecules 12,546 (1979)). The monomer can be viewed as a cyclic analog of methyl methacrylate, and the reactivity in free radical polymerization is comparable to or exceeding that of methyl methacrylate (Akkapeddi et.al, Journal of Polymer Science: Polymer Chemistry Edition, v20, 2819, (1982), and Polymer, vol20, 1215, (1979)). The high free radical reactivity is probably due to molecular ring strain.

MBL readily copolymerizes with styrene and (meth) acrylate monomers, and copolymers with (meth) acrylate esters, acrylonitrile and styrene have been reported (Journal of Polymer Science: Polymer Chemistry Edition, v20, 2819 (1982)). ). JP90333736 discloses a transparent heat resistant resin comprising a copolymer of MBL and a (meth) acrylate monomer. US 5,880,235 discloses MBL copolymers for producing cast glass and heat dimensionally stable molding materials. US 6,642,346 discloses compositions comprising MBL copolymers for automotive clearcoats and clearcoat finishes. This patent discloses that the introduction of exomethylene lactone or lactam improves finish scratching and scratch resistance (column 1, lines 63-65). US 6,723,790 discloses blends of MBL copolymers with other polymers. US 6,841,627 discloses MBL graft copolymers and blends of the copolymers with thermoplastic resins to obtain good optical properties and heat and weather resistance. US 2003/0130414 describes compositions of MBL copolymers filled with alumina trihydrate for decorative sheets and articles. This composition has heat resistance, hardness, scratch and scratch resistance, antibacterial properties, a low coefficient of thermal expansion, a high refractive index and a high degree of transparency. There are no references describing copolymers of MBL with styrene and methyl methacrylate (MMA) with high T _g , weatherability and solvent resistance.

(easy explanation)
It was unexpectedly discovered that a copolymer of MBL with styrene and methyl methacrylate and a copolymer of MBL with styrene, methyl methacrylate and acrylonitrile have excellent weather resistance and significantly improved solvent resistance. The T _g is significantly higher than the corresponding polymers made with styrene and acrylonitrile alone (SAN) or with styrene, acrylonitrile and methyl methacrylate (MMA-SAN). High weather resistant multilayer articles can be constructed therefrom.

  Accordingly, in some embodiments, the present invention relates to copolymers comprising structural units derived from α-methylene-γ-butyrolactone, styrene, methyl methacrylate, and optionally acrylonitrile. The copolymer has a glass transition temperature in the range of about 110 ° C to about 175 ° C, preferably about 120 ° C to about 150 ° C.

  In another aspect, the present invention relates to a multilayer article comprising at least one protective layer disposed on a substrate. The protective layer comprises a UV absorber; and an MBL copolymer comprising structural units derived from MBL, styrene, methyl methacrylate, and optionally acrylonitrile, and the substrate comprises a UV sensitive material.

  In yet another aspect, the present invention relates to a multilayer article comprising a silicone hard coat; at least one protective layer comprising MBL copolymer, and a substrate comprising a UV sensitive material.

(Detailed explanation)
In one embodiment, the present invention is derived from α-methylene-γ-butyrolactone, a copolymer comprising structural units derived from styrene and methyl methacrylate, and derived from α-methylene-γ-butyrolactone, styrene, methyl methacrylate and acrylonitrile. The present invention relates to a copolymer containing the structural unit. These copolymers typically have a glass transition temperature in the range of about 110 ° C to about 175 ° C, particularly about 120 ° C to about 150 ° C. In the MBL copolymer, the amount of structural units derived from α-methylene-γ-butyrolactone is from about 10% to about 75%, especially from about 20% to about 50%, even from about 20% to about It is in the range of 35% by weight. The amount of structural units derived from styrene ranges from about 20% to about 80%, in particular from about 20% to about 50%, and even from about 25% to about 40% by weight. The amount of structural units derived from methyl methacrylate ranges from about 5% to about 50%, in particular from about 10% to about 45%, and even from about 15% to about 45%. In copolymers comprising structural units derived from acrylonitrile, the amount of such units is from 5% to about 40% by weight, in particular from about 5% to about 35% by weight. For all copolymers, where the amount is expressed in weight percent, the amount is based on the total weight of the copolymer. The introduction of MBL in MMA-SAN polymer, typically improves weatherability, increases at the same time T _g, improved chemical resistance, does not become yellow during melt processing.

  Any of the known methods for polymerizing styrene and / or (meth) acrylate monomers can be used to prepare the α-MBL copolymer. However, bulk polymerization methods and solution polymerization methods using solvents such as γ-butyrolactone, toluene, NMP, DMF and DMSO are particularly suitable.

  In another aspect, the invention relates to a multilayer article comprising a protective layer disposed on a substrate. The protective layer comprises a copolymer of α-methylene-γ-butyrolactone and methyl methacrylate, styrene and / or acrylonitrile, in particular the MBL copolymer as described above. The protective layer is typically placed directly on the substrate, but it may be desirable to laminate the protective layer to the substrate using an adhesive or primer layer.

  Protective layers include fillers (clay, talc, etc.), reinforcing agents (glass fibers), impact modifiers, plasticizers, glidants, lubricants and other processing aids, stabilizers, antioxidants, electrification Additives such as inhibitors, colorants, mold release agents, flame retardants, antioxidants, hindered amine light stabilizers, and / or UV absorbers (UVA) may be included. Suitable UVAs include hydroxybenzophenone, hydroxyphenylbenzotriazole, hydroxyphenyltriazine, cyanoacrylate, oxanilide, benzoxazinone; and particulate inorganic materials such as titanium oxide, cerium oxide, and zinc oxide having a particle size of less than about 100 nm. It is done. Known in the art, “Plastics Additives Handbook”, 5th edition, H.C. Other UVAs disclosed in standard references such as Zweifel, Hanser Publishers can also be used. Mixtures of UVA are particularly effective, in particular mixtures of said substances. In a particular embodiment, UVA is 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- 5 sold as TINUVIN (R) 1577 by CIBA (R). Hexyloxy-phenol.

  The amount of UVA used in the protective layer is from about 0.0005% to about 10% by weight, in particular from about 0.001% to about 10% by weight, based on the total weight of the polymer in the protective layer, and more preferably about 0.000. It ranges from 1% to about 5% by weight. The thickness of the protective layer in the multilayer article is typically from about 2μ to about 2500μ, preferably from about 10μ to about 500μ, most preferably from about 50μ to about 250μ.

  The substrate used in the multilayer article in the various aspects of the present invention is a material that is sensitive to UV radiation, i.e., exhibits some undesirable change upon exposure to UV. Undesirable changes are typically color changes, but the chemical and mechanical properties of the substrate can also be affected. UV photosensitive materials include thermoplastic and thermosetting polymers and copolymers, and blends thereof. Suitable thermoplastic polymers include polycarbonates, in particular aromatic polycarbonates, polyacetals, polyarylates, polyarylene ethers such as polyphenylene ether, polyarylene sulfides such as polyphenylene sulfide, polyimides such as polyamideimide, polyetherimides, Polyether ketones such as polyaryl ether ketones, polyether ether ketones, polyether ketone ketones, polyamides, polyesters such as liquid crystalline polyesters, polyether esters, polyether amides, polyester amides, and polyester carbonates, aliphatic olefins and functionalities Olefin polymers (eg, polyethylene, polypropylene, thermoplastic polyolefin (TPO), ethylene-pro Such as lencopolymers, polyvinyl chloride, poly (vinyl chloride-co-vinylidene chloride), polyvinyl fluoride, polyvinylidene fluoride, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyacrylonitrile, polymethyl methacrylate (PMMA) ( (Meth) acrylate polymers and copolymers), and polymers and copolymers of vinyl aromatic monomers such as acrylonitrile-butadiene-styrene copolymers (ABS) and acrylonitrile-styrene (ASA). In particular, the substrate may be one or more homo- or co-polycarbonates, or blends of polycarbonates, or blends of polycarbonate and other polymers, such as blends of polycarbonate and polyesters, ABS copolymers or ASA copolymers. It may be. Although other thermoplastic polymers may be present there, the aforementioned polymers or blends typically constitute the major part thereof.

  Suitable polycarbonates include homo and copolycarbonates containing structural units of the formula

In the formula, each A ¹ and A ² is a monocyclic divalent aryl group, Z is a bridging group, and one or more carbon atoms thereof separate A ¹ and A ² . In particular, A ¹ and A ² may be unsubstituted phenylene or substituted derivatives thereof, and the bridging group Z may be methylene, cyclohexylidene or isopropylidene. More particularly, the polycarbonate may be bisphenyl A polycarbonate. The polycarbonate may be a copolyester carbonate. Such polymers, in addition to the carbonate units, -A ¹ -Z-A ² which, such as isophthalate and / or terephthalate, bonded to aromatic dicarboxylate groups - containing ester unit having a partial. Suitable polyesters include poly (alkylene dicarboxylates), particularly poly (ethylene terephthalate) (PET), poly (1,4-butylene terephthalate) (PBT), poly (trimethylene terephthalate) (PTT), poly ( Ethylene naphthalate) (PEN), poly (butylene naphthalate) (PBN), poly (cyclohexanedimethanol terephthalate), poly (cyclohexanedimethanol-co-ethylene terephthalate) (PETG) and poly (1,4-cyclohexanedimethyl-) 1,4-cyclohexanedicarboxylate) (PCCD).

  Suitable polyarylates include structural units derived from aromatic dihydroxy compounds and aromatic dicarboxylic acid compounds, in particular structural units derived from terephthalate and / or isophthalate structural units in combination with bisphenol A and / or resorcinol. . Suitable polyetherimides are described in US Pat. Nos. 3,803,085 and 3,905,942.

  Blends of any of the above polymers can also be used. These include blends of thermosetting polymers with thermoplastic polymers such as polyphenylene ether, polyphenylene sulfide, polysulfone, polyetherimide or polyester. The thermoplastic polymer is typically combined with a thermosetting monomer mixture prior to curing. Also included are blends of cellulosic materials with thermosetting and / or thermoplastic polymers.

  Substrates containing polymer materials are silicate, zeolite, titanium dioxide, stone powder, glass fiber or sphere, carbon fiber, carbon black, graphite, calcium carbonate, talc, mica, lithopone, zinc oxide, zirconium silicate, oxidation Fillers such as iron, diatomaceous earth, calcium carbonate, magnesium oxide, chromium oxide, zirconium oxide, aluminum oxide, ground quartz, calcined clay, talc, kaolin, asbestos, cellulose, wood flour, coke, cotton and synthetic textile fibers, especially Reinforcing fillers such as glass fibers and carbon fibers, and colorants such as metal flakes, glass flakes and beads, ceramic particles, other polymer particles, and dyes and pigments that may be organic, inorganic or organometallic , May be mixed.

  Multilayer articles can be prepared by a variety of known methods such as solvent coating, film lamination, profile extrusion, sheet extrusion, coextrusion, extrusion blow molding and thermoforming, and injection molding. For example, a multilayer article may be formed by coextruding the protective layer and the substrate.

  In some embodiments, the multilayer article may further comprise a silicone hard coat disposed over the protective layer. In this case, MBL copolymer may be used as a primer for the silicone hard coat. MBL copolymers used with silicone hardcoats contain structural units derived from other vinyl monomers in addition to structures derived from MBL. Suitable vinyl monomers include methyl methacrylate, ethyl acrylate, butyl acrylate, hydroxyethyl methacrylate, acrylonitrile, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, acrylic acid. Methyl, ethyl acrylate, n-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, acrylamide or methacrylamide, acrylic acid (Meth) acrylic acid such as dimethylaminoethyl and dimethylaminoethyl methacrylate, glycidyl acrylate and glycidyl methacrylate and Derivatives of al, as well as styrene, vinyl toluene, aromatic vinyl compounds such as α- methylstyrene and t- butyl styrene. In particular, copolymers of MBL with methyl methacrylate, styrene, and / or acrylonitrile, including those such as those described above, can be used.

There are no restrictions on the type of silicone hardcoat that may be used other than adhering to the protective layer / primer. Thus, coatings prepared from basic, neutral or acidic colloidal silica may be used. Examples of the silicone hard coat that can be used when the MBL copolymer is used as a protective layer / primer include, for example, colloidal silica and a formula: RSi (OR) ₃₇ (wherein each R independently represents a carbon number of 1 to 3). Or a mixture of trialkoxysilanes or a mixture of trialkoxysilanes, which is prepared by hydrolyzing an aqueous dispersion of the alkyl group, or a substituted or unsubstituted aromatic group, preferably a methyl group. The hard coat may include conventional additives such as compatible UV absorbers and polysiloxane polyether copolymers. Other additives such as thickeners, pigments and dyes may also be included for conventional purposes. A description of the preparation of suitable silicone hardcoats can be found in US Pat. S. 4,373,061.

(Definition)
In the context of the present invention, alkyl is intended to include linear, branched or cyclic hydrocarbon structures and combinations thereof, such as lower alkyl and higher alkyl. Preferred alkyl groups are those having C ₂₀ or less. Lower alkyl means an alkyl group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, and includes methyl, ethyl, n-propyl, isopropyl, and n-, s- and t-butyl. Higher alkyl means an alkyl group having 7 or more carbon atoms, preferably 7 to 20, and includes n-, s- and t-heptyl, octyl and dodecyl. Cycloalkyl is a subordinate concept of alkyl, and examples thereof include cyclic hydrocarbon groups having 3 to 8 carbon atoms. Cycloalkyl groups include, for example, cyclopropyl, cyclobutyl, cyclopentyl and norbornyl.

  Aryl and heteroaryl are 5- or 6-membered aromatic or heteroaromatic rings containing 0 to 3 heteroatoms selected from nitrogen, oxygen or sulfur; 0 to 3 selected from nitrogen, oxygen or sulfur A 9- or 10-membered aromatic or heteroaromatic ring system containing 1 heteroatom; or a 13- or 14-membered aromatic containing 0-3 heteroatoms selected from nitrogen, oxygen or sulfur or Means a heteroaromatic ring system. Aromatic 6- to 14-membered carbocyclic rings include, for example, benzene, naphthalene, indane, tetralin and fluorene; and 5- to 10-membered aromatic heterocyclic rings include, for example, imidazole, pyridine, indole Thiophene, benzopyranone, thiazole, furan, benzimidazole, quinoline, isoquinoline, quinoxaline, pyrimidine, pyrazine, tetrazole and pyrazole.

  Arylalkyl means an alkyl residue appended to an aryl ring. Examples are benzyl and phenethyl. Heteroarylalkyl means an alkyl residue appended to a heteroaryl ring. Examples include pyridinylmethyl and pyrimidinylethyl. Alkylaryl means an aryl group having one or more appended alkyl groups. Examples are tolyl and mesityl.

  Alkoxy or alkoxyl means a group having 1 to 8 carbon atoms that is linear, branched, cyclic, and combinations thereof appended to the parent structure through oxygen. Examples are methoxy, ethoxy, propoxy, isopropoxy, cyclopropyloxy, and cyclohexyloxy. Lower alkoxy means a group having 1 to 4 carbon atoms.

  Acyl means a group having 1 to 8 carbon atoms, linear, branched, cyclic, saturated, unsaturated and aromatic and combinations thereof, which is added to the parent structure via a carbonyl group. To do. As long as the point of addition to the parent compound remains carbonyl, one or more carbons of the acyl group may be replaced with nitrogen, oxygen or sulfur. Examples are acetyl, benzoyl, propionyl, isobutyryl, t-butoxycarbonyl, and benzyloxycarbonyl. Lower acyl means a group having 1 to 4 carbon atoms.

  Heterocycle means a cycloalkyl or aryl residue in which 1 to 3 carbons are substituted with a heteroatom such as oxygen, nitrogen or sulfur. Heteroaryls falling within the scope of the present invention include pyrrolidine, pyrazole, pyrrole, indole, quinoline, isoquinoline, tetrahydroisoquinoline, benzofuran, benzodioxane, benzodioxole (when present as a substituent, generally methylenedioxy (Referred to as phenol), tetrazole, morpholine, thiazole, pyridine, pyridazine, pyrimidine, thiophene, furan, oxazole, oxazoline, isoxazole, dioxane, and tetrahydrofuran, triazole, benzotriazole, and triazine.

Substituent means a structural unit such as, but not limited to, alkyl, alkylaryl, aryl, arylalkyl and heteroaryl; wherein up to three H atoms in the residue are lower alkyl, substituted alkyl, Aryl, substituted aryl, haloalkyl, alkoxy, carbonyl, carboxy, carboxyalkoxy, carboxyamide, acyloxy, amidino, nitro, halo, hydroxy, OCH (COOH) ₂ , cyano, primary amino, secondary amino, acylamino, alkylthio, sulfoxide , Sulfone, phenyl, benzyl, phenoxy, benzyloxy, heteroaryl or heteroaryloxy; each of said phenyl, benzyl, phenoxy, benzyloxy, heteroaryl and heteroaryloxy is optional , Lower alkyl, alkenyl, alkynyl, halogen, hydroxy, haloalkyl, alkoxy, cyano, phenyl, benzyl, benzyloxy, carboxamide, heteroaryl, heteroaryloxy, nitro or —NRR (where R is independently H, lower Alkyl or cycloalkyl, -RR is fused to form a cyclic ring with nitrogen, and is substituted with 1 to 3 substituents.

Haloalkyl means an alkyl group in which one or more H atoms are replaced by halogen atoms, and the term haloalkyl includes perhaloalkyl. Examples of haloalkyl groups that fall within the scope of the present invention include CH ₂ F, CHF ₂ and CF ₃ .

  Any numerical value used here includes all values of one unit from a low value to a high value, but there is at least 2 units of opening between any low value and high value. For example, if the amount of a component or the value of a process variable such as, for example, temperature, pressure and time is stated to be 1-90, preferably 20-80, more preferably 30-70, this specification In the book, values such as 15-85, 22-68, 43-51, and 30-32 should be clearly listed. For values less than 1, one unit is considered 0.0001, 0.001, 0.01 or 0.1 as appropriate. These are only examples specifically shown, and all possible combinations of numerical values between the lowest and highest values listed should be considered as clearly stated in this application as well. It is.

(Example)
<Example 1: Copolymer synthesis>
Materials: α-methylene-γ-butyrolactone was obtained from TCI, and methyl methacrylate, styrene and acrylonitrile were all obtained from Aldrich. All were purified from prohibited substances using a basic alumina column just prior to use.

General polymerization procedure: A vacuum flask was charged with the required amount of styrene, acrylonitrile, α-methylene-γ-butyrolactone, methyl methacrylate based on the intended composition, with γ-butyrolactone as the solvent. AIBN was added as a radical initiator. If necessary, chain transfer agents can be added. The concentration was kept below 50%, preferably 30% to avoid reaction exotherm. The flask was degassed twice by a freeze-thaw cycle with a nitrogen purge upon thawing. The oil bath temperature for heating was maintained at 65-70 ° C. for 4 hours and then cooled to room temperature. The polymer sample was precipitated twice in methanol and dried overnight in a low temperature vacuum oven. The polymer composition was determined by quantitative C ₁₃ analysis.

  Poly (styrene-co-acrylonitrile-co-methyl methacrylate-co-α-methylene-γ-butyrolactone) with Mw of 30-220 kDaltons was made in different ratios. The composition and molecular weight are shown in Table 1.

  Molecular weight and polydispersity were maintained at Polymer Laboratories size exclusion column (PLgel 5 μm MIXED-C, 300 × 7.5 mm, 40 ° C.) using chloroform with 3.6% (v / v) isopropanol as mobile phase. ) With a Perkin Elmer Series 200 GPC.

T _g was measured on a Perkin-Elmer DSC-7 using Pyris software. Typical DSC sample size was 5-10 mg and DSC heating and cooling rate was 20 ° C./min. The results are shown in Table 1. The T _g of the polymer containing about 20-30 mol% α-methylene-γ-butyrolactone was increased by about 20-30% over the composition without α-methylene-γ-butyrolactone.

  TGA samples (3.5-7.0 mg) were tested in air using a Perkin Elmer TGA 7 while scanning the temperature at a heating rate of 10 ° C./min. TGA analysis also showed that the copolymer was thermally stable up to at least 350 ° C.

<Example 2: Determination of weather resistance>
In a Carver press, a polymer powder sample was compression molded into a film about 100 microns thick using Teflon-coated aluminum foil as a shim at a temperature of about 160 ° C. and a pressure of 4000 psi. The film was placed on an aluminum frame and exposed in an Atlas Ci4000 xenon arc weatherometer. The xenon arc lamp had a CIRA (IR-reflective quartz) inner filter and a soda lime glass outer filter to optimize sunlight. Samples were continuously irradiated at 340 nm with a dose of 0.75 W / m ² / nm (excluding the spray period). At a relative humidity of 30%, the black panel temperature was 55 ° C and the air temperature was 35 ° C. Samples received a 30 minute water spray once a week.

  Color measurements were made in transfer mode using a GretagMacbeth ColorEye 7000A spectrometer. The color is reported as a yellow index according to ASTM D-1925. The results are shown in FIG. All of the MBL copolymers did not turn yellower than commercial SAN or MMASAN.

<Example 3: Solvent resistance>
Films were tested for resistance to strong bases and organic solvents compared to SAN and MMASAN. The MBL copolymer film was prepared using the procedure shown in Example 2. The film was placed in a crystallization dish and a drop (25 μL) of the test chemical was placed on the film surface with a dispensing pipette. The dish containing the sample was placed in a 65 ° C. oven for 1 hour. Pass or fail observations were made as to whether the film was visually damaged. The results are shown in Table 2. The MBL copolymer showed improved chemical resistance.

<Example 4: Multilayer article>
Preparation: For MMASAN 530, PMMA, SAN581 and MBL (# 33, # 38 and # 41) samples, 2.0 g caplayer polymer in 9 mL chloroform and TINUVIN® 1577 UV absorber (Ciba Specialty Chemicals product) ) A solution was made from 0.02 g. The composition is shown in Table 3.

The solution was poured onto a glass plate and stretched using a 10 mil doctor blade to evaporate the solvent. The film was floated from the glass with water and further dried at 65 ° C. for 2 hours in a forced air oven. The final film was about 40 microns thick. A portion of the film was laminated onto 2 1/2 ^" x 2 1/2 ^" x 1/8 "plaque of Lexan® 140 polycarbonate resin containing 2% titanium dioxide pigment. In a heating press at 165 ° C. for 3 1/2 minutes at a contact pressure followed by 1 minute at 4000 psi and 1/2 minute at 6000 psi The cap layer was firmly adhered to the polycarbonate resin. The sample without the cap layer was a non-laminated Lexan polycarbonate plaque.

<Example 5: Toluene resistance>
A drop of toluene was placed on the surface of the sample for 1 or 2 minutes at room temperature and then wiped off with a cotton swab. The surface was visually assessed for damage and judged as none, negligible, slight, severe, or very bad. The results are shown in Table 4. The results show that the tulipaline-containing sample has good to excellent resistance to toluene and the copolymer of styrene, acrylonitrile and methyl methacrylate is very poor.

Example 6: Enhanced weather resistance of multilayer article
Samples were exposed in an Atlas Ci35a xenon arc weatherometer at the conditions shown in Table 5. Samples were removed after an exposure period of 2785 kJ / m ² / nm measured at 340 nm. This amount of exposure is equivalent to about a year in Miami, Florida. The change in color was measured with a Macbeth Colorey 7000A spectrometer as the change in yellowing index (ΔYI) defined by ASTM D 1925. The results are shown in Table 4. These indicate that laminates made from tulipaline-containing copolymers have less color change than non-laminated polycarbonate, SAN laminates and are superior or comparable to MMASAN copolymers.

  While only certain features of the invention have been shown and described herein, many modifications and changes will occur to those skilled in the art. Accordingly, the appended claims should be construed to include all such modifications and changes as fall within the true spirit of the invention.

2 is a graph showing the weather resistance of MBL copolymers compared to styrene-acrylonitrile copolymers or copolymers of styrene, acrylonitrile and methyl methacrylate.

Claims (12)

  A copolymer comprising structural units derived from α-methylene-γ-butyrolactone, styrene, methyl methacrylate, and optionally acrylonitrile.   The copolymer of claim 1 comprising structural units derived from acrylonitrile.   The amount of structural units derived from α-methylene-γ-butyrolactone ranges from about 10 wt% to about 75 wt%, preferably from about 20 wt% to about 35 wt%, based on the total weight. The copolymer according to 1.   The amount of structural units derived from styrene is from about 20% to about 80%, preferably from about 20% to about 50%, more preferably from about 20% to about 40%, based on the total weight. The copolymer of claim 1 in the range of%.   The amount of structural units derived from methyl methacrylate is from about 5% to about 50%, preferably from about 10% to about 45%, more preferably from about 15% to about 5%, based on the total weight. The copolymer of claim 1 in the range of 45 wt%.   The copolymer of claim 1 wherein the amount of structural units derived from acrylonitrile ranges from about 0 wt% to about 40 wt%, preferably from about 10 wt% to about 35 wt%, based on the total weight.   A substrate and at least one protective layer disposed thereon, the at least one protective layer comprising an α-methylene-γ-butyrolactone copolymer, and optionally at least one UV absorber, preferably 2- ( 4,6-diphenyl-1,3,5-triazin-2-yl) -5-hexyloxy-phenol, wherein the α-methylene-γ-butyrolactone copolymer is α-methylene-γ A multilayer article comprising structural units derived from butyrolactone, styrene, methyl methacrylate, and optionally acrylonitrile, wherein the substrate comprises a UV sensitive material.   The multilayer article according to claim 1, further comprising a silicone hard coat disposed on the protective layer. Silicone hard coat,
Copolymer comprising structural units derived from α-methylene-γ-butyrolactone, and optionally at least one UV absorber, preferably 2- (4,6-diphenyl-1,3,5-triazin-2-yl) At least one protective layer comprising -5-hexyloxy-phenol;
A multilayer article comprising a substrate comprising a UV sensitive material.   The multilayer article of claim 9, wherein the copolymer further comprises structural units derived from methyl methacrylate.   The multilayer article of claim 9, wherein the copolymer further comprises structural units derived from styrene.   The multilayer article of claim 9, wherein the copolymer further comprises structural units derived from acrylonitrile.

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