Methyl methacrylate-based copolymer and optical grade molding composition comprising same

Abstract

The present invention relates to copolymers based on methyl methacrylate and norbornene-type monomers, which have improved heat resistance, high transparency and low haze values. Furthermore, the invention relates to molding compositions comprising the copolymers according to the invention and to a method for easily producing the copolymers according to the invention by free-radical polymerization. The molding compositions of the present invention are well suited for the manufacture of molded articles which can be used as optical elements in various optical devices, for example as light guides or lampshades.

Description

Technical Field

[0001] This invention relates to copolymers based on methyl methacrylate and norbornene monomers, which exhibit improved heat resistance, high transparency, and low haze values. Furthermore, this invention relates to molding compositions comprising the copolymers of this invention and methods for readily producing the copolymers of this invention via free radical polymerization. The molding compositions of this invention are ideally suited for manufacturing molded articles, which can be used as optical elements in various optical devices, such as light guides or lampshades. Background Technology

[0002] Copolymers containing repeating units derived from methyl methacrylate (MMA) (often referred to as polymethyl methacrylate (PMMA) for simplicity) are typically transparent materials with high weather resistance, particularly high resistance to solar UV radiation. The weather resistance of PMMA can be further improved by adding UV absorbers, stabilizers, and inhibitors if desired. Therefore, PMMA is commonly used in applications requiring high transparency, low haze, and high weather resistance.

[0003] The demand for polymers with exceptionally high heat resistance for optical applications is also growing. These applications include, for example, light sources for indoor and outdoor use, including high-power LEDs, where such polymers are used as light guides, optical lenses, etc. To increase the light output of LEDs, optical components are positioned very close to the LED. The operating temperature of LED surfaces, especially that of so-called white high-power LEDs, often exceeds 100°C or sometimes even exceeds 130°C. Therefore, it is important that materials used in these applications have high transparency and exceptionally low haze values, as well as high thermal stability. Additionally, the material should have high weather resistance and show virtually no signs of yellowing after long-term exposure to solar radiation.

[0004] Several copolymers containing methyl methacrylate (MMA) with improved thermal stability are described in the prior art. For example, WO 2022 / 122806 A1 describes copolymers of methyl methacrylate, (meth)acrylic acid, and optional comonomers, and methods for their production, wherein the copolymers and molding compositions comprising them should have high heat resistance and low glutaric anhydride unit content. Furthermore, documents WO 2021 / 219738 and WO 2017 / 097979 A1 describe copolymers of MMA and methacrylic acid, and methods for their production. These copolymers typically exhibit a Vicat temperature of approximately 116°C. To increase the Vicat temperature of these copolymers up to 120°C and higher, the amount of methacrylic acid units must be increased. However, higher amounts of methacrylic acid units result in insufficient processability and higher water absorption. Typically, water absorption lowers the Vicat softening temperature of the polymer.

[0005] Furthermore, copolymers of MMA, maleic anhydride, and styrene are known in the prior art. For example, WO 2005 / 108486 A1 and WO 2020 / 126722 A1 describe such copolymers and blends containing said copolymers. The transparency of these copolymers and blends is often insufficient for a variety of optical applications. Another disadvantage is that the presence of styrene typically impairs weather resistance.

[0006] Imidinated alkyl poly(meth)acrylates, such as polymethylmethacrylimide (PMMI), are also known in the prior art (e.g., WO 2009 / 135703 A1). Typically, PMMI exhibits high heat resistance, including around 120°C and higher Vicat temperatures; however, the production of these imidized polymers is delicate and expensive, and their optical properties, such as transmittance and yellowness, are often insufficient for a variety of optical applications requiring high standards. Additionally, PMMI is highly hygroscopic due to the methacrylimide groups, and typically, polymers or polymer blends with high moisture content have lower Vicat temperatures.

[0007] It is known from the prior art that the free radical copolymerization of norbornene and alkyl (meth)acrylate involves several difficulties. It has been reported that the free radical copolymerization of norbornene with methyl acrylate can be carried out in solution polymerization using a long reaction time of 20 hours (see Comparative Example 1, KR 2009 / 0020344 A). Furthermore, in Copolymers of norbornene and its derivatives with acrylates-Promising materials for optoelectronics (drop Copolymers of borneol and its derivatives with acrylates – promising materials for optoelectronics. Bykov, VI, et al., *Doklady Chemistry*, 2011, Vol. 439, Part 2, pp. 227-229, describes the free radical copolymerization of norbornene and acrylate monomers (e.g., methyl acrylate, tert-butyl acrylate, and acrylic acid) using benzoyl peroxide as an initiator. Reference RU 2 456 304 C2 describes the free radical copolymerization of acrylate monomers (particularly methyl acrylate) and norbornene. For example, this copolymer can be prepared by polymerizing a monomer mixture with a norbornene:methyl acrylate monomer ratio of 3:1 to 1:1 mol / mol at a temperature of 25 to 30 °C in the presence of a free radical initiator (e.g., benzoyl peroxide). Conversely, the free radical copolymerization of norbornene with methyl methacrylate (MMA) is described not to result in the incorporation of NB into the polymer chain (see Comparative Example 2, JP H04 63810 A), particularly due to the steric hindrance of the α-methyl group.

[0008] The publication Yeh An-Chi, "Free Radical-Induced Copolymerization of Norbornene and Methacrylate," December 31, 2008 (URL: https: / / www.jofamericanscience.org / journals / am-sci / 0401 / 13_0401_yeh_am.pdf), describes the preparation of a norbornene-methacrylate copolymer formed by free radical polymerization using an N,N'-azobisisobutyronitrile (AIBN) initiator. The copolymer exhibits a relatively low molecular weight of less than 30,000 g / mol and can be used to prepare thin, optically transparent films.

[0009] It is known that norbornene can undergo radical copolymerization with electron-deficient monomers, such as maleic anhydride, for example, as described by Hiroshi Ito et al. "Fundamental Aspects of Norbornene-Maleic-Anhydride Co and Terpolymers for 193 nm Lithography: Polymerization Chemistry and Polymer Properties (Basic aspects of norbornene-maleic anhydride copolymers and terpolymers for 193 nm photolithography: Polymerization) (Combined chemical and polymer properties) In the *Journal of Photopolymer Science and Technology*, 2000, pp. 559-589, further, free radical terpolymers of norbornene, maleic anhydride, and methacrylic acid monomers such as tert-butyl acrylate or methacrylic acid are described in Hiroshi Ito et al. For example, terpolymers of MMA, norbornene, and electron-deficient comonomers (e.g., maleic anhydride, maleimide, or N-cyclohexylmaleimide or vinyl chloride) and their synthesis via free radical polymerization are described in WO 2021 / 259965 A1, JP H04 63810 A; and FR2699540A1. However, such terpolymers including, for example, maleic anhydride generally exhibit undesirable high water absorption and often show significant yellowing. Therefore, such terpolymers are often unsuitable for high-standard optical applications, especially at elevated temperatures up to 100°C.

[0010] Another approach to obtaining copolymers of olefin monomers (e.g., ethylene or norbornene) and alkyl methacrylate monomers (e.g., methyl acrylate and methyl methacrylate) involves coordination polymerization (or also known as insertion polymerization) using transition metal complex catalysts (particularly palladium-based ones) (e.g., KR 2021 / 0019282A). The publication TANAKARYO et al., “Synthesis of high-molecular weight block copolymers of norbornene and propylene with methyl methacrylate initiated by a fluorenylamido titanium complex,” POLYMER CHEMISTRY, Vol. 4, No. 14, (2013-01-01), pp. 3974-3980, describes the preparation of norbornene / propylene / MMA copolymers using coordination-insertion polymerization with titanium complexes.

[0011] Furthermore, it is known in the prior art that alkyl (meth)acrylate / norbornene copolymers are produced by metal-catalyzed polymerization. For example, document US 2007 / 0255027 A1 relates to a method for preparing an olefin-acrylate-norbornene terpolymer by free radical polymerization in the presence of a Lewis acid, such as a metal halide or metal oxide. Document KR2009 / 0020344 A also relates to free radical polymerization in the presence of a metal compound acting as a Lewis acid. The copolymer comprises 0.1 to 30 mol% of a cyclic olefin monomer (e.g., norbornene), 10 to 99 mol% of an acrylate monomer (e.g., methyl acrylate), and 0.1 to 50 mol% of an unsaturated organic acid monomer (e.g., methacrylic acid). The use of metal catalysts necessitates special filtration processes to remove the catalyst, which increases production costs. Undesirable metal residues in the polymer impair, for example, weather stability and often increase haze.

[0012] There is a great need for new copolymers based on (meth)acrylate alkyl esters, particularly MMA, which exhibit improved heat resistance, carbon content, high transparency and good processability, as well as limited hygroscopicity and low metal content. Summary of the Invention

[0013] Purpose of the invention

[0014] In view of the above-mentioned drawbacks, one object of the present invention is to provide a copolymer that possesses excellent optical properties, particularly low haze, and combined with high thermal stability, such as a Vicat temperature of at least 105°C. These properties would allow the polymer to be used with light sources (e.g., high-power white LEDs) with high operating temperatures on its surface. Furthermore, the polymer needs to be suitable for long-term use when exposed to ultraviolet light and / or elevated temperatures, and needs to have limited water absorption and excellent weather resistance, particularly high stability to solar radiation.

[0015] Another object of the present invention is to provide a method for manufacturing such copolymers on an industrial scale in a cost-effective and quality-efficient manner. For example, the use of metal-based catalysts that need to be removed from the polymer product should be avoided. Invention Overview

[0017] Surprisingly, it has been found that a transparent copolymer of methyl methacrylate (MMA) and 2-norbornene (NB) can be obtained by free radical polymerization at a reaction temperature above 100°C, preferably above 120°C, more preferably above 130°C, wherein the starting monomer mixture or monomer feed contains at least 20 mol%, preferably at least 25 mol%, of norbornene monomer based on the total amount of monomers in the starting monomer mixture. The copolymer of the present invention obtained by the method of the present invention contains at least 70.0 mol% MMA, 1.0 to 30 mol% NB, and optionally selected comonomer c), wherein the weight-average molecular weight M of the copolymer is... w The concentration is 40,000 to 300,000 g / mol, and the sum of repeating units derived from methyl methacrylate, NB and optional comonomer c) is at least 95.0 mol%, preferably at least 98.0 mol%.

[0018] Another aspect of the invention relates to a method for producing the copolymer of the invention, comprising: free radical copolymerization of a monomer mixture comprising MMA, a norbornene compound of formula (I) and optionally at least one comonomer c) and / or d) to form the copolymer of the invention, which is generally in the form of a copolymer solution, a copolymer dispersion or a copolymer suspension, wherein the reaction temperature in copolymerization step (a) is above 100°C, and the monomer mixture comprises at least 10 mol% of a norbornene compound of formula (I).

[0019] Another aspect of the invention relates to a molding composition comprising the copolymer of the invention and optionally one or more known polymer additives. In particular, the molding compositions of the invention exhibit excellent high thermal stability and low haze. Specifically, when the molding composition does not contain colorants or scattering agents, the Vicat temperature (according to ISO 306-B50 (2014)) of the molding compositions of the invention is at least 105°C, and the haze (according to ASTM D1003 (2013), 3.0 mm) of the molding compositions is typically less than 3%. Invention Details

[0021] This invention relates to a copolymer comprising (all amounts given in mol% are based on the total copolymer):

[0022] a) 70.0 to 99.0 mol%, preferably 75.0 to 99.0 mol%, more preferably 80.0 to 98.5 mol% of repeating units derived from methyl methacrylate;

[0023] b) 1.0 to 30.0 mol%, preferably 1.0 to 25.0 mol%, more preferably 1.5 to 20.0 mol%, of repeating units of the compound represented by the derived free formula (I).

[0024] (I)

[0025] Wherein the substituent R 1 R 2 R 2a R 3 and R 3a Hydrocarbon groups that independently represent hydrogen atoms and have 1 to 12 carbon atoms; hydroxyl (-OH); hydroxyalkyl; carboxyl (-C(O)OH); -C(=O)-NH2; -C(=O)-R x ;-C(=O)-OR x ;where R x It is a C1-12-alkyl or C6-12-cycloalkyl; or R 2 and R 3 Together they can form a ring-shaped structure; and

[0026] c) 0.0 to 15.0 mol%, preferably 0.0 to 10.0 mol%, of repeating units derived from at least one optional comonomer c) selected from acrylic acid, methacrylic acid, vinyl aromatic monomers, alkyl acrylates and alkyl methacrylates other than methyl methacrylate;

[0027] The weight-average molecular weight M of the copolymer, as determined by GPC, is... wThe concentration is 40,000 to 300,000 g / mol, preferably 50,000 to 200,000 g / mol;

[0028] And wherein, based on the total copolymer, the sum of a) repeating units derived from methyl methacrylate, b) repeating units derived from the compound represented by formula (I) and c) repeating units derived from optional comonomer c) is at least 95.0 mol%, preferably at least 98.0 mol%.

[0029] As used herein, the term "(meth)acrylate" refers to methacrylates, such as methyl methacrylate, ethyl methacrylate, etc., and acrylates, such as methyl acrylate, ethyl acrylate, etc., and mixtures thereof. As used herein, the term "(meth)acrylate alkyl ester" may represent a single alkyl ester of (meth)acrylate or a mixture of different alkyl esters of (meth)acrylate.

[0030] Preferably, the copolymers of the present invention are obtained by free radical polymerization. According to the present invention, the term "free radical polymerization" or equivalent terms, such as "free radical polymeric," are understood to refer to a chain polymerization reaction, wherein chain initiation involves the dissociation of free radical polymerization initiator molecules (e.g., commonly known organic initiators selected from organic peroxides and azo compounds) into free radicals via heat and / or light. In particular, free radical polymerization does not involve the use of any metal catalyst or metal compound directly involved in the polymerization. The term "free radical polymerization" is commonly known to those skilled in the art and generally includes the fact that the concentration of free radicals is not constant during polymerization and that chain termination occurs, especially increasing at high conversion rates. Therefore, this free radical polymerization differs from commonly known controlled free radical polymerization. Furthermore, free radical polymerization as a chain polymerization reaction differs from coordination polymerization (or also called insertion polymerization) which typically uses transition metal complex catalysts.

[0031] According to a preferred embodiment, the copolymers of the present invention are obtained by free radical polymerization, preferably without the use of any metal or metal compound as an initiator and / or catalyst.

[0032] Preferably, the copolymer of the present invention comprises, based on the total copolymer and calculated by metal, less than 50 ppm, preferably less than 10 ppm, more preferably less than 5 ppm, and even more preferably less than 3 ppm of a metal or metal compound, and relates to a metal selected from transition metals and aluminum (Al), more preferably to one or all metals selected from aluminum (Al), iron (Fe), and nickel (Ni). The amounts given above may refer to the amount of a specific metal or metal compound present in the copolymer of the present invention or the sum of all metals and metal compounds.

[0033] Preferably, the copolymer of the present invention is a statistical copolymer or a random copolymer. Typically, in a statistical copolymer, the sequence of repeating units along the copolymer chain follows statistical rules.

[0034] Typically, in random copolymers, the molar ratio of repeating units in a specific segment of the chain is equal to the molar ratio of repeating units in the entire copolymer. In this document, the copolymers of the present invention are generally not block copolymers, alternating copolymers, or graft copolymers.

[0035] More preferably, the copolymer of the present invention contains, based on the total copolymer and calculated by metal, less than 50 ppm, preferably less than 10 ppm, more preferably less than 5 ppm, and even more preferably less than 3 ppm of a metal or metal compound, and refers to the sum of all metals present in the copolymer of the present invention. More preferably, the copolymer of the present invention is free from any transition metals, aluminum, and their compounds. Generally, according to the present invention, the term "free from" or any corresponding term is understood to mean that one or more of the mentioned compounds are absent or present at levels below the detection limit, which relates to commonly known polymer analysis techniques, such as atomic absorption spectrometry (AAS) typically after digestion; NMR techniques; wet chemical analysis (e.g., titration methods).

[0036] Unless otherwise specified, the term “ppm” as used herein refers to weight ppm (e.g., mg / kg).

[0037] In a preferred embodiment, based on the total copolymer, the sum of a) repeating units derived from a) methyl methacrylate, b) repeating units derived from the compound represented by formula (I), and c) repeating units derived from optional comonomer c) is at least 99.0 mol%, more preferably at least 99.9 mol%. It is also preferred that the copolymer is entirely composed of repeating units derived from a) methyl methacrylate, b) repeating units derived from the compound represented by formula (I), and c) repeating units derived from optional comonomer c). It is also preferred that the copolymer is entirely composed of repeating units derived from a) methyl methacrylate, b) repeating units derived from the compound represented by formula (I), and optionally c) repeating units derived from comonomer c), said comonomer c) being selected from alkyl acrylates, such as methyl acrylate and ethyl acrylate. The term "entirely composed of..." means that, based on the total amount of monomer repeating units in the copolymer, the sum of the mentioned repeating units is 100.0 mol%. As is known to those skilled in the art, such copolymers may contain small amounts of groups generated by free radical polymerization initiator molecules and / or chain transfer agents.

[0038] According to a preferred embodiment, in the copolymer of the present invention, the content p of repeating units of the compound represented by the derivative free formula (I) in the copolymer, expressed in mol% b This can be described by the following relation:

[0039] 0.01 p a ≤ p b ≤ 0.4 p a ,

[0040] More preferably, it can be described by the following relation:

[0041] 0.04 p a ≤ p b ≤ 0.3 p a ,

[0042] Where p a It is the content of repeating units derived from methyl methacrylate in the copolymer, expressed in mol% (%).

[0043] Preferably, the copolymer of the present invention has a Vicat softening temperature of at least 105°C, more preferably at least 110°C, and even more preferably at least 115°C, according to ISO 306-B50 (2014). More preferably, the copolymer of the present invention has a Vicat softening temperature in the range of 105°C to 135°C, and even more preferably in the range of 110°C to 130°C.

[0044] In particular, the copolymer of the present invention has a haze of less than 3.0%, preferably less than 2.0%, and more preferably less than 1.5%, wherein the haze is measured at 23°C on an injection-molded specimen with a thickness of 3.0 mm prepared from the copolymer of the present invention, according to standard ASTM D1003 (2013). It is also preferred that the haze of the copolymer is in the range of 0.01% to 2.9%, particularly preferably in the range of 0.1% to 1.4%.

[0045] Furthermore, according to DIN 5033-7 (2014), the light transmittance T of the copolymer of the present invention was measured at 23°C on an injection-molded specimen with a thickness of 3.0 mm prepared from the copolymer of the present invention. D65 Within the range of 85% to 93%, more preferably within the range of 87% to 92.5%.

[0046] In a particularly preferred embodiment, the copolymer of the present invention comprises, based on the total copolymer and calculated by metal, less than 50 ppm, preferably less than 10 ppm, more preferably less than 5 ppm, and even more preferably less than 3 ppm of a metal or metal compound, and relating to the sum of all metals present in the copolymer; wherein the haze of the copolymer of the present invention is less than 3.0%, preferably less than 2.0%, more preferably less than 1.5%, wherein the haze is measured at 23°C on an injection-molded specimen with a thickness of 3.0 mm prepared from the copolymer of the present invention according to standard ASTM D1003 (2013); and wherein the light transmittance T of the copolymer of the present invention is measured at 23°C on an injection-molded specimen with a thickness of 3.0 mm prepared from the copolymer of the present invention according to DIN 5033-7 (2014). D65 Within the range of 85% to 93%, more preferably within the range of 87% to 92.5%.

[0047] Surprisingly, it was found that low levels of metal ions improved the transparency and transmittance of the copolymer.

[0048] Compound of formula (I) (monomer b)

[0049] The copolymer of the present invention comprises 1.0 to 30.0 mol%, preferably 1.0 to 25.0 mol%, more preferably 1.5 to 20.0 mol%, and even more preferably 1.5 to 15.0 mol% of repeating units of a compound represented by derivative free formula (I).

[0050] (I)

[0051] Substituent R 1 R 2 R 2a R 3 and R 3a Hydrocarbon groups that independently represent hydrogen atoms and have 1 to 12 carbon atoms; hydroxyl (-OH); hydroxyalkyl; carboxyl (-C(O)OH); -C(=O)-NH2; -C(=O)-R x ;-C(=O)-OR x ;where R x It is a C1-12-alkyl or C6-12-cycloalkyl; or R 2 and R 3 They can together form a ring-shaped structure.

[0052] According to a preferred embodiment, the substituent R 1 A hydrocarbon group representing a hydrogen atom and having 1 to 12 carbon atoms, preferably 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms. More preferably, the substituent R... 1 Represents a hydrogen atom or a C1-C4 alkyl group. Most preferably, the substituent R1 Represents a hydrogen atom or a methyl group. More preferably, the substituent R 1 It represents a hydrogen atom.

[0053] For example, R 2 and R 3 These components can together form a cyclic structure portion, wherein the cyclic structure portion is preferably a 5- to 7-membered ring (including carbon atoms of the norbornene structure), and preferably includes one or more heteroatoms selected from N and O. Preferably, the cyclic structure portion is...

[0054] i) The dicarboxyimide structure represented by formula (Ia)

[0055] (Ia)

[0056] Where Ry represents a hydrogen atom, a hydrocarbon group having 1 to 12 carbon atoms, a hydroxyl group (-OH), or a hydroxyalkyl group; or

[0057] ii) The structure of dicarboxylic anhydrides represented by formula (Ib)

[0058] (Ib)

[0059] Typically, a hydroxyalkyl group is a straight-chain or branched C1-C12 alkyl group substituted with one or more, preferably one or two, hydroxyl groups, provided that if two or more hydroxyl groups are present, they are not two or more hydroxyl groups on the same carbon atom. Preferably, the hydroxyalkyl group is composed of -R x -OH indicates that R x As defined above. Examples of hydroxyalkyl groups are hydroxymethyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 1-(hydroxymethyl)-2-methylpropyl, 2-hydroxybutyl, 3-hydroxybutyl, 4-hydroxybutyl, 2,3-dihydroxypropyl, 1-(hydroxymethyl)-2-hydroxyethyl, 2,3-dihydroxybutyl, 3,4-dihydroxybutyl, and 2-(hydroxymethyl)-3-hydroxypropyl.

[0060] As used herein, the term "hydrocarbon group" includes alkyl, cycloalkyl, aryl, aralkyl, and alkylaryl groups. These groups may be branched or straight-chain. Furthermore, these groups may have one or more substituents. Substituents are, for example, straight-chain and branched alkyl groups having 1 to 12, preferably 1 to 6, carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, 2-methylbutyl, hexyl, or 2-ethylhexyl; cycloalkyl groups, such as cyclopentyl and cyclohexyl; and aryl groups, such as phenyl or naphthyl.

[0061] Preferred alkyl groups include methyl, ethyl, propyl, isopropyl, 1-butyl, 2-butyl, 2-methylpropyl, tert-butyl, isobutyl, pentyl, 2-methylbutyl, 1,1-dimethylpropyl, hexyl, heptyl, octyl, 1,1,3,3-tetramethylbutyl, nonyl, 1-decyl, 2-decyl, undecyl, and dodecyl. Preferred cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl, each optionally substituted with one or more branched or straight-chain alkyl groups. Preferred aryl groups according to the invention may be derived from phenyl, naphthyl, and biphenyl, each optionally substituted with one or more branched or straight-chain alkyl groups.

[0062] Substituent R 2 R 2a R 3 and R 3a Each can be independently configured as either exo- or endo-. In R 2a and R 3a In the case of hydrogen, the substituent R 2 and R 3 They can also be in cis or trans configurations relative to each other.

[0063] For example, the compound of formula (I) is selected from one or more of the following: 2-norbornene (2-NB); 5-norbornene-2,3-dicarboxylic anhydride; 3-methyl-5-norbornene-2,3-dicarboxylic anhydride; 5-methyl-5-norbornene-2,3-dicarboxylic anhydride; 2-carboxylic acid-5-norbornene; 2,3-dicarboxylic acid-5-norbornene; 2(2-hydroxyethyl)-2-carboxylic acid-5-norbornene; 2(2-hydroxyethyl)-3-carboxylic acid-5-norbornene; 2-carboxylic acid- 2-tert-butyl-5-norbornene; 2-carboxylic acid-3-tert-butyl-5-norbornene; 2,3-dimethyl-2,3-dicarboxylic acid-5-norbornene; 5-norbornene-2-ol; 5-norbornene-2,2-diethanol; 5-norbornene-2,3-diethanol; 2-acetyl-5-norbornene; methyl 5-norbornene-2-carboxylate; 2-carboxylate-2-ethyl-5-norbornene; 2-carboxylate-3-ethyl-5-norbornene; 5-norbornene-2-formamide; N -(2-ethylhexyl)-5-norbornene-2,3-dicarboximide; and N -Hydroxy-5-norbornene-2,3-dicarboximide.

[0064] According to a preferred embodiment, the compound represented by formula (I) (monomer b) is 2-norbornene (2-NB). In particular, the use of 2-NB has been shown to provide a copolymer with excellent optical properties and high thermal stability.

[0065] Optional comonomer c)

[0066] In addition to repeating units derived from MMA and repeating units derived from compounds of formula (I), the copolymers of the present invention may further comprise (in each case, based on the total copolymer) 0.0 to 15.0 mol%, preferably 0.0 to 10.0 mol%, more preferably 0.0 to 7.0 mol% of repeating units derived from at least one optional comonomer c), said comonomer c) selected from acrylic acid, methacrylic acid, vinyl aromatic monomers, alkyl acrylates, and alkyl methacrylates other than methyl methacrylate. Preferably, the copolymer may comprise 0.01 to 10.0 mol%, more preferably 0.1 to 5.0 mol% of repeating units derived from at least one optional comonomer c), said comonomer c) preferably selected from acrylic acid, methacrylic acid, methyl acrylate, and ethyl acrylate.

[0067] Preferably, the optional comonomer c) is at least one monomer selected from methacrylic acid, acrylic acid, methyl acrylate and ethyl acrylate.

[0068] For the purposes of this invention, C1-C (meth)acrylic acid is preferred. 18 Alkyl esters, advantageously (meth)acrylic acid C1-C 10 Alkyl esters, particularly C1-C4 alkyl esters of (meth)acrylate. Most preferred alkyl methacrylates other than methyl methacrylate (MMA) include ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, n-heptyl methacrylate, n-octyl methacrylate, n-isooctyl methacrylate, and n-ethylhexyl methacrylate, n-nonyl methacrylate, n-decyl methacrylate, as well as cycloalkyl methacrylates, such as cyclohexyl methacrylate, isobornyl methacrylate, or ethylcyclohexyl methacrylate. Preferred alkyl acrylates include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate, isooctyl acrylate, n-nonyl acrylate, n-decyl acrylate, and n-ethylhexyl acrylate, as well as cycloalkyl acrylates, such as cyclohexyl acrylate, isobornyl acrylate, or ethylcyclohexyl acrylate.

[0069] Examples of suitable aromatic vinyl monomers include styrene; mono- or polyalkyl styrene, such as o-methylstyrene, m-methylstyrene, p-methylstyrene, o-, p-dimethylstyrene, o-ethylstyrene, m-ethylstyrene, and p-ethylstyrene; functionalized styrene derivatives, such as methoxystyrene, ethoxystyrene, vinylbenzoic acid, methyl vinylbenzoate, vinyl benzyl acetate, hydroxystyrene, o-chlorostyrene, p-chlorostyrene, and divinylbenzene; 3-phenylpropene, 4-phenylbutene, and α-methylstyrene. Styrene is the most preferred.

[0070] Using alkyl acrylates, methacrylic acid, and acrylic acid as optional comonomers (c) results in even better flowability of the copolymer, wherein the preferred alkyl acrylates are selected from methyl acrylate, ethyl acrylate, butyl acrylate, hexyl acrylate, isobornyl acrylate, and ethylhexyl acrylate. Additionally, isobornyl methacrylate, norbornyl methacrylate, tert-butyl methacrylate, and α-methylstyrene can also be used as optional comonomers (c). For the best balance between optical properties and high thermal stability, the at least one optional comonomer (c) is preferably selected from methacrylic acid, acrylic acid, methyl acrylate, and ethyl acrylate.

[0071] If further improvements to the flowability and / or particularly low water absorption of the copolymers of the present invention are required, styrene or methacrylates such as butyl methacrylate, ethylhexyl methacrylate, or aliphatic methacrylates of fatty acids such as octyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, methacrylate palmitate, and other aliphatic C4 esters may also be used. 12 -C 24 Methacrylate is used as an optional comonomer (c).

[0072] According to a preferred embodiment, the copolymer of the present invention comprises one or two optional comonomers selected from methacrylic acid, acrylic acid, methyl acrylate, and ethyl acrylate. More preferably, the copolymer of the present invention may comprise an optional comonomer selected from methacrylic acid and acrylic acid, and an optional comonomer selected from methyl acrylate and ethyl acrylate.

[0073] Optional comonomer d)

[0074] In addition to repeating units derived from MMA (monomer a), repeating units derived from the compound of formula (I) (monomer b), and repeating units derived from optional comonomer c), the copolymers of the present invention may also contain 0.0 to 5.0 mol%, preferably 0.0 to 2.0 mol%, more preferably 0.0 to 1.0 mol% of repeating units derived from another optional comonomer d), which is different from monomers a), b), and c) and can be radically copolymerized with methyl methacrylate (monomer a) and / or the compound of formula (I) (monomer b) and / or optional comonomer c).

[0075] For example, optional comonomer d) is selected from (meth)acrylonitrile, maleic anhydride (MAH), maleimide, methylmaleimide, N -Phenylanimide and N -One or more monomers of cyclohexylmaleimide.

[0076] According to a preferred embodiment, the copolymer of the present invention is free from derivatives selected from maleic anhydride (MAH), maleimide, methylmaleimide, N -Phenylanimide and N -Any repeating unit of the monomer of cyclohexylmaleimide.

[0077] Furthermore, the optional comonomer d) may be one or more monomers selected from crosslinking monomers, wherein the crosslinking monomer has two or more polymerizable double bonds in its molecule. The crosslinking monomer may be selected from difunctional (meth)acrylates, trifunctional or polyfunctional (meth)acrylates, and other known crosslinking agents. For example, the crosslinking monomer may be selected from allyl (meth)acrylate; (meth)acrylic anhydride; 1,2-butanediol-di-(meth)acrylate; ethylene glycol dimethyl (meth)acrylate; trimethylolpropane-tri(meth)acrylate; 1,12-dodecanediol-di(meth)acrylate; and divinylbenzene. For example, difunctional (meth)acrylates are diesters of (meth)acrylic acid and polyfunctional alcohols, such as di(meth)acrylates of propylene glycol, butanediol, hexanediol, octyl glycol, nonanediol, decanediol, eicosanediol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dodecyl (ethylene glycol), tetradecyl (ethylene glycol), propylene glycol, dipropylene glycol, and tetradecyl (propylene glycol). For example, trifunctional or polyfunctional (meth)acrylates are triesters or polyesters of (meth)acrylic acid and polyfunctional alcohols, such as trimethylolpropane tri(meth)acrylate and pentaerythritol tetra(meth)acrylate. Suitable crosslinking monomers are described, for example, in WO 02 / 20634 and EP 0 522 351. Typically, at least one optional monomer (d) selected from the crosslinking monomers described above may be present in an amount from 0.001 to 1.0 mol% based on the total copolymer. Preferably, the amount of crosslinking monomer is adjusted so that the copolymer can be processed by any known thermoplastic method, such as extrusion and injection molding.

[0078] Preparation of copolymers

[0079] Another aspect of the invention relates to a method for producing the copolymer of the invention as described above, comprising:

[0080] (a) A copolymerization step, comprising a monomer mixture including MMA, a monomer of formula (I), and optionally at least one optional comonomer (c) undergoing free radical copolymerization to form a copolymer, typically in the form of a copolymer solution, wherein the reaction temperature in copolymerization step (a) is above 100°C, preferably above 120°C, more preferably above 130°C, and wherein the monomer mixture comprises at least 10 mol%, preferably at least 20 mol%, more preferably at least 30 mol% of at least one monomer represented by formula (I) based on the total monomer mixture.

[0081] (I)

[0082] Wherein the substituent R 1 R 2 R 2a R 3 and R 3aHydrocarbon groups that independently represent hydrogen atoms and have 1 to 12 carbon atoms; hydroxyl (-OH); hydroxyalkyl; carboxyl (-C(O)OH); -C(=O)-NH2; -C(=O)-R x ;-C(=O)-OR x ;where R x It is a C1-12-alkyl or C6-12-cycloalkyl; or R 2 and R 3 They can together form a ring-shaped structure.

[0083] Preferred embodiments of the norbornene monomers and optional comonomers c) of formula (I) as described above are accordingly applicable to the method of the present invention.

[0084] copolymerization step (a)

[0085] Radical copolymerization of monomer mixtures containing MMA is well known in the art. The copolymerization in step (a) can be carried out in a state containing the monomer mixture, a radical polymerization initiator, and optionally a chain transfer agent, and substantially no solvent (bulk polymerization). Alternatively, a solvent capable of dissolving the copolymer can be present or added during polymerization (solution polymerization).

[0086] In a preferred embodiment, the copolymerization in step (a) is carried out by bulk polymerization. In particular, for the purposes of this invention, bulk polymerization refers to a monomer mixture comprising (preferably composed of) monomers a), b) and optionally c) and / or d), a free radical polymerization initiator and optionally a chain transfer agent, and other components, such as solvents described below, not more than 5% by weight, preferably not more than 2% by weight, based on the total monomer mixture.

[0087] According to a preferred embodiment, a method for producing the copolymer of the present invention includes a copolymerization step in which a monomer mixture comprising MMA, a monomer of formula (I), optionally at least one optional comonomer (c), and at least one free radical polymerization initiator selected from organic peroxides and azo compounds undergoes free radical copolymerization to form a copolymer. Preferably, the reaction mixture contains no or only low amounts of transition metals and aluminum (Al) and their compounds as described below, more preferably metals selected from aluminum (Al), iron (Fe), and nickel (Ni) and their compounds. Also preferably, based on the total amount of the reaction mixture and the sum of all metals present in the reaction mixture, the reaction mixture contains less than 100 ppm, preferably less than 50 ppm, more preferably less than 10 ppm of metals and metal compounds. Also preferably, based on the total amount of monomers in the reaction mixture and the sum of all metals present in the reaction mixture, the reaction mixture contains less than 200 ppm, preferably less than 100 ppm, more preferably less than 50 ppm of metals and metal compounds.

[0088] For example, the free radical polymerization initiator can be one or more compounds selected from organic peroxides and azo compounds. Preferably, the free radical polymerization initiator is at least one compound selected from organic peroxides. For example, suitable organic peroxides may be selected from tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl peroxylaurate, tert-butyl peroxyisopropyl monocarbonate, tert-hexyl peroxyisopropyl monocarbonate, tert-butyl peracetate, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, tert-butyl peroxy-2-ethylhexanoate (TBPEH), and tert-butyl peroxyisobutyrate. Ester, di-tert-pentyl peroxide, didecyl peroxide, tert-pentyl peroxide-2-ethylhexyl carbonate, tert-hexyl peroxide-2-ethylhexanoate, di-tert-butyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, lauroyl peroxide, benzoyl peroxide, tert-butyl peroxide-neodecanate, tert-butyl peroxypentanoate, tert-butyl peroxide-2-ethylhexanoate, tert-butyl peroxide-benzoate, and diisopropylbenzene peroxide. For example, suitable azo compounds may be selected from 2-(carbamoylazo)-isobutyronitrile, 1,1'-azobis(1-cyclohexanecarboxylonitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), dimethyl 2,2'-azobisisobutyrate, 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane), 2,2'-azobis-4-methoxy-2,4-dimethylpentanitrile, and 2,2'-azobis-2,4-dimethylpentanitrile.

[0089] Preferably, the reaction temperature in copolymerization step (a) is in the range of 100°C to 200°C, more preferably 120°C to 180°C, and even more preferably 130°C to 180°C. Preferably, copolymerization step (a) is carried out at a pressure in the range of 1 bar to 50 bar.

[0090] Preferably, based on the total amount of polymerizable components or more preferably based on the total monomer mixture (e.g. in the case of bulk polymerization), the monomer mixture (e.g., the total monomer feed in continuous or quasi-continuous polymerization) contains 10.0 to 70.0 mol%, preferably 20.0 to 60.0 mol%, more preferably 30.0 to 50.0 mol% of at least one monomer represented by formula (I), preferably 2-norbornene.

[0091] In a preferred embodiment, the content m of compound (monomer b) represented by formula (I) in the total monomer mixture during copolymerization step (a) (e.g., in the total monomer feed of a continuous polymerization process) is expressed in mol% as m. b This can be described by the following relation:

[0092] 0.2 m a ≤ m b ≤ 2.0 m a

[0093] More preferably, it can be described by the following relation:

[0094] 0.25 m a ≤ m b ≤ 1.5 m a

[0095] Where m a It is the content of methyl methacrylate (monomer a) in the monomer mixture, expressed in mole percent.

[0096] Preferably, based on the total amount of polymerizable components or more preferably based on the total monomer mixture, the monomer mixture (e.g., total monomer feed) in copolymerization step (a) comprises (preferably) the following substances:

[0097] a) 30.0 to 90.0 mol%, preferably 40.0 to 80.0 mol%, more preferably 49.9 to 70.0 mol% of methyl methacrylate;

[0098] b) 10.0 to 70.0 mol%, preferably 20.0 to 60 mol%, more preferably 30.0 to 50.0 mol%, of the compound represented by formula (I), more preferably 2-norbornene; and

[0099] c) 0.0 to 15.0 mol%, preferably 0.0 to 10 mol%, more preferably 0.01 to 10 mol%, of at least one optional comonomer c), selected from acrylic acid, methacrylic acid, vinyl aromatic monomers, alkyl acrylates and alkyl methacrylates other than methyl methacrylate; more preferably selected from methacrylic acid, acrylic acid, methyl acrylate and ethyl acrylate.

[0100] For example, based on the total amount of polymerizable components or preferably based on the total monomer mixture, the monomer mixture (e.g., the total monomer feed) in copolymerization step (a) comprises (preferably) the following substances:

[0101] a) 30.0 to 80.0 mol%, preferably 49.9 to 75.0 mol% of methyl methacrylate;

[0102] b) 20.0 to 60.0 mol%, preferably 25.0 to 50 mol%, of the compound represented by formula (I), preferably 2-norbornene;

[0103] c) 0.0 to 10.0 mol%, preferably 0.1 to 8 mol%, of at least optional comonomer c), selected from acrylic acid, methacrylic acid, vinyl aromatic monomers, alkyl acrylates, and alkyl methacrylates other than methyl methacrylate; preferably selected from methacrylic acid, acrylic acid, methyl acrylate, and ethyl acrylate; and

[0104] d) 0.0 to 5.0 mol%, preferably 0.0 to 1.0 mol%, of at least one optional comonomer.

[0105] Typically, the conversion rate in copolymerization step (a) is at least 40%, preferably at least 45%. As used herein, the term "conversion rate" refers to the average weight ratio of the copolymer formed in copolymerization step (a) to the total monomer feed.

[0106] Preferably, the reaction time or total average residence time of the copolymerization step (a) is in the range of 10 minutes to 10 hours, more preferably 15 minutes to 6 hours, for example 20 minutes to 4 hours.

[0107] Typically, in the case of batch polymerization, the reaction time of copolymerization step (a) can be in the range of 1 to 30 hours, preferably 4 to 24 hours.

[0108] The copolymerization step (a) can be carried out in a discontinuous (batch) or semi-batch reactor type, wherein a free radical polymerization initiator, monomer, and, if present, solvent or any combination of these are optionally supplied during the copolymerization step (a). Alternatively, the copolymerization step (a) can be carried out by continuous polymerization, such as in a stirred tank reactor (CSTR), a tubular reactor or a combination thereof, a kneader, or a disc-ring reactor.

[0109] In some embodiments, the polymer reaction mixture from the outlet of the first CSTR can be successively and continuously supplied to a second and / or third reaction unit, such as an additional CSTR or tubular reactor, to improve conversion.

[0110] Discontinuous reactors (batch), semi-batch reactors, and CSTRs can be equipped with any type of mixing element to homogenize the reaction mixture in the reactor. These reactors are also referred to as backmixing reactors in the literature (Octave Levenspiel, Chemical Reaction Engineering, 3rd Edition, Wiley 1998). In a further embodiment, the discontinuous reactor (batch) does not contain a mixing element. The copolymerization step can be carried out additionally on cast sheets.

[0111] There are no particular restrictions on the design of discontinuous reactors (batch), semi-batch reactors, and CSTRs. A typical example is a vessel equipped with an agitator bearing mixing elements such as paddles, blades, anchors, or helical mixing elements. The polymerization vessel optionally contains a heating or cooling jacket with circulating hot oil, water, or steam to heat or cool the reaction mixture during polymerization. Another effective method of heat removal is to cool the reaction mixture by supplying monomers and / or solvents at temperatures below the polymerization temperature. Alternatively, the heat of polymerization can be removed by boiling the reaction mixture.

[0112] The copolymerization step (a) can also be carried out in a continuous tubular reactor. A continuous tubular reactor contains at least one inlet for the monomer or prepolymer reaction mixture and at least one outlet for the polymer reaction mixture. The tubular reactor can also be a bundled tube reactor, where polymerization takes place, for example, in one or more parallel tubes. Alternative tubular reactors can also be plate heat exchangers. Unlike CSTRs, tubular reactors do not contain a reaction mixture that is adequately mixed or homogenized throughout the entire reaction volume. As defined in the literature (Octave Levenspiel, Chemical Reaction Engineering, 3rd Edition, Wiley 1998), a typical tubular reactor contains a large concentration gradient between the inlet and outlet areas. The tubular reactor may optionally contain static mixing elements or agitators to homogenize the reaction mixture in the radial direction. Examples of static mixing elements include SMX and SMR type Sulzer tubular mixers, Kenics static mixers, Toray tubular mixers, etc. Alternatively, the tubular reactor may not contain any mixing elements. Heat removal from polymerization in the tubular reactor can optionally be achieved by a jacket filled with water or hot oil. Alternatively, the heat of polymerization can be removed by boiling and cooling the reaction mixture.

[0113] Those skilled in the art can readily adjust the conversion rate by adaptively modifying the average residence time of the reaction mixture in the reactor, the polymerization temperature, the reactivity and amount of the free radical polymerization initiator used, and the monomer concentration in the reactor feed. For example, if CSTR is used, the average residence time is preferably selected in the range of 10 minutes to 10 hours, more preferably 15 minutes to 6 hours, and for example, 20 minutes to 4 hours. If the average residence time is less than 20 minutes, the amount of free radical polymerization initiator must be increased, making it difficult to control the polymerization reaction. Average residence times of more than 7 hours are generally disadvantageous in terms of productivity and cost efficiency.

[0114] There are no particular restrictions on the polymerization vessel used as CSTR in step (a), as long as the reaction mixture is thoroughly mixed during copolymerization step (a).

[0115] In one embodiment of the invention, the copolymerization step (a) is carried out in a continuous stirred tank reactor (CSTR), and the composition and temperature of the reaction mixture can be kept substantially homogeneous by means of a suitable stirrer installed in the polymerization vessel. Typically, a CSTR-type reactor equipped with a stirrer having stirring blades capable of keeping the solution in the vessel substantially completely mixed is used.

[0116] The shape of the agitator blades can be any known shape. For example, double-helix blades, paddle blades, turbine blades, propeller blades, brumagin blades, multi-stage blades, anchor blades, max blend blades, puddle blades, MIG blades, full-zone blades, and Logborn blades manufactured by Kobelco Eco-Solutions Co., Ltd. are all suitable for this purpose. In particular, double-helix blades are especially preferred due to their high mixing efficiency. Furthermore, baffles are preferably installed in the polymerization vessel to enhance the mixing effect.

[0117] If solution polymerization is used, there are no particular restrictions on the solvent used in step (a), as long as it can dissolve the copolymer at the polymerization temperature described above and does not interfere with the polymerization process except for a small amount of chain transfer. One or more solvents selected from aromatic hydrocarbons, ketones, ethers, esters, amides, and alcohols can be used. Examples of solvents that can be used include, but are not limited to, well-known organic solvents such as toluene, xylene, 2,5-dimethylfuran, acetone, methyl ethyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, ethyl isobutyl ketone, tetrahydrofuran, dioxane, butyl acetate, ethyl acetate, dimethylformamide, diethylformamide, dimethylacetamide, diethylacetamide, etc. N -Methylpyrrolidone, methanol, ethanol, isopropanol, ethylene glycol, propylene glycol, 2-methoxy-2-propanol, and tetraethylene glycol dimethyl ether, or any mixture thereof. If the copolymerization step (a) is carried out in a solvent, the solvent content in the reaction mixture is typically between 3.0% by weight and 60% by weight, more preferably between 5.0% by weight and 45% by weight, based on the total weight of the reaction mixture.

[0118] Preferably, the copolymerization step (a) is carried out as a bulk polymerization or in the presence of a solvent, preferably selected from toluene, xylene, butyl acetate, ethyl acetate, dimethyl furan, methyl ethyl ketone or any mixture thereof, preferably as a bulk polymerization.

[0119] Heating step (b)

[0120] According to the invention, the copolymer solution obtained in polymerization step (a) may optionally be continuously supplied to a step (heating step (b)) in which the copolymer solution is heated to a temperature of 100°C to 300°C. Typically, the optional heating step may be carried out in a heat exchange apparatus of generally known type.

[0121] De-volatile step (c)

[0122] Subsequently, the material can be supplied to the devolatification unit in a subsequent devolatification step to separate and remove unreacted monomers or mixtures of unreacted monomers and solvents (if present) (devolatification step (c)).

[0123] In the devolatilization step, the temperature of the copolymer solution or the melt temperature of the copolymer is typically below 300°C, more preferably 150°C to 300°C, and even more preferably 170°C to 280°C. The preferred pressure in the final devolatilization zone of the devolatilization step is typically below 950 mbar, preferably below 500 mbar, and more preferably below 200 mbar. There is no lower limit to the absolute pressure in the devolatilization step, but for technical reasons, it is typically at least 10 mbar or higher. If the pressure in the devolatilization step is above 500 mbar, even if the devolatilization is carried out within the stated temperature range, the non-reactive monomers or mixtures consisting of non-reactive monomers and polymerization solvents cannot be effectively separated or removed. This is detrimental in terms of the thermal stability, mechanical properties, and optical properties of the resulting copolymer.

[0124] As an apparatus for performing such volatilization, a single-screw or twin-screw extruder, a flash chamber, a degassing kneader, or a combination thereof can be used. One embodiment uses an apparatus having a cylindrical container and an agitator having multiple stirring elements attached to a rotating shaft, and the apparatus having at least one or more vents at the top of the cylindrical portion, a supply port at one end of the cylindrical portion for supplying the copolymer solution, and a discharge port at the other end for removing the copolymer after volatilization. The number of rotating shafts is not limited, but is typically 1 to 5, preferably 1 or 2, and more preferably an apparatus with two rotating shafts. In particular, vented continuous single-screw or twin-screw extruders (kneading devices and intermittent melt kneading devices) are preferred; references can be made to single-screw extruders, twin-screw extruders, twin-screw / single-screw combined continuous kneading extruders, and three-screw extruders, respectively, having one or more "Unimelt" type screws, as well as continuous or intermittent kneaders. In particular, it is preferable to use a vented single-screw or twin-screw extruder or a continuous twin-screw reactor with multiple convex lens-type and / or elliptical blades.

[0125] Furthermore, the devolatileization step in the production method of the present invention can be carried out by using two or more devolatileization devices arranged in series, which is advantageous because it can further reduce the residual volatile components in the copolymer obtained after devolatileization.

[0126] The degassed unreacted monomers and solvents may optionally be recycled and reused in the copolymerization step (a), either alone or with new monomers and optionally new solvents.

[0127] Molding composition

[0128] Another aspect of the invention relates to a molding composition comprising the copolymer of the invention and optionally at least one additive selected from ultraviolet absorbers, ultraviolet stabilizers, antioxidants, colorants, flow improvers, antistatic agents, lubricants and release agents, scattering particles, scratch improvers, etc.

[0129] The preferred embodiments and scope defined for the copolymers of the present invention are accordingly applied to the molding compositions of the present invention. In particular, the amounts of metals or metal compounds as defined above for the copolymers of the present invention, preferably transition metals and aluminum (Al), and more preferably metals selected from aluminum (Al), iron (Fe) and nickel (Ni), are also applicable to the molding compositions of the present invention.

[0130] In particular, the molding compositions of the present invention exhibit excellent high thermal stability. Preferably, the Vicat softening temperature of the molding compositions of the present invention, as measured according to ISO 306-B50 (2014), is at least 105°C, more preferably at least 110°C, even more preferably 115°C, and even more preferably in the range of 105 to 135°C, and even more preferably in the range of 110 to 130°C.

[0131] The molding compositions of the present invention exhibit excellent transparency and a transparent, substantially non-cloudy appearance. In particular, preferably without color additives, pigments, or scattering agents, the haze of the molding composition is less than 5.0%, more preferably less than 4.0%, more preferably less than 3.0%, and even more preferably less than 1.0%, wherein the haze is measured at 23°C on an injection-molded specimen with a thickness of 3.0 mm according to standard ASTM D1003 (2013). It is also preferably that the haze of the molding composition is in the range of 0.01% to 2.9%, particularly preferably in the range of 0.1% to 1.4%.

[0132] Furthermore, preferably when the molding composition does not contain color additives, coloring pigments, or scattering agents, the molding composition of the present invention preferably exhibits a light transmittance T in the range of 85% to 93%, more preferably in the range of 87% to 92.5%. D65 It is measured at 23°C on an injection-molded specimen with a thickness of 3.0 mm, according to DIN 5033-7 (2014).

[0133] Further findings indicate that molded articles with higher thickness and excellent transparency, such as optical conductors, can be prepared from the copolymers of the present invention. In this paper, measured at 23°C on injection-molded specimens with a thickness of 150.0 mm according to DIN 5033-7 (2014), the molding compositions of the present invention exhibit a light transmittance T in the range of 75% to 93%, more preferably in the range of 80.0% to 92.5%. D65 .

[0134] The yellowness index of the molding composition of the present invention, preferably less than 5, more preferably less than 3, and more preferably less than 2, when the molding composition does not contain color additives, coloring pigments or scattering agents, according to DIN 6167 (1980) (Light Source D) 65 The measurement was taken at 23°C on an injection-molded specimen with a thickness of 3.0 mm at a 10° angle.

[0135] The yellowness index of the molding composition of the present invention, preferably less than 12, and more preferably less than 8, should be determined in the absence of color additives, pigments, or scattering agents in the molding composition, according to DIN 6167 (1980) (Light Source D). 65 The measurement was taken at 23°C on an injection-molded specimen with a thickness of 150.0 mm at a 10° angle over a 3.0 mm layer thickness.

[0136] Specifically, the ranges given above regarding haze, transmittance, and / or yellowness index apply to molding compositions that do not contain any colorants and / or scattering agents. In particular, such scattering agents also include unwanted impurities, such as metal salts and agglomerated metal salts.

[0137] Due to their advantageous rheological properties, such as the melt volumetric flow rate (MVR) measured according to ISO 1133 (2012), the molding compositions of the present invention are well-suited for manufacturing optical elements by means of injection molding.

[0138] The molding composition may contain at least one common polymer additive, provided that the latter does not adversely affect the optical properties of the copolymer of the present invention. Various polymer additives are well known to those skilled in the art and include, in particular, ultraviolet absorbers, ultraviolet stabilizers, light stabilizers, antioxidants, colorants, flow modifiers, flame retardants, lubricants and release agents, scattering particles, etc. The thermal stability of the resulting molding composition should not be excessively impaired by these additives.

[0139] UV absorbers, UV stabilizers, and light stabilizers used in this invention are well known and described in detail, for example, in Hans Zweifel, *Plastics Additives Handbook*, Hanser Publishing, 5th edition, 2001, page 141 and subsequent pages. UV stabilizers are understood to include both UV stabilizers and free radical scavengers. Free radical scavengers are, for example, sterically hindered phenols, such as, but not limited to, octadecyl 3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate, pentaerythritol tetra[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate. UV absorbers may, for example, be derived from substituted benzophenones, salicylates, cinnamic acid esters, oxaloyl aniline, benzo[…]. Phosphine, hydroxyphenylbenzotriazole, benzotriazole, triazine, or benzylmalonate. The total content of the UV absorber in the molding composition is typically from 0.01% to 1.0% by weight, particularly from 0.01% to 0.5% by weight, and especially from 0.02% to 0.2% by weight, based on the weight of the molding composition.

[0140] Ultraviolet absorbers can be present in molding compositions as low molecular weight compounds. However, ultraviolet-absorbing groups in the matrix polymer molecules can also be covalently bonded after copolymerization with polymerizable ultraviolet-absorbing compounds (e.g., acrylic, methacrylic, or allyl derivatives of benzotriazole or benzophenone derivatives). As those skilled in the art will readily appreciate, mixtures of chemically different ultraviolet absorbers, such as combinations of benzotriazole and triazine, can also be used.

[0141] The most well-known representatives of UV stabilizers / free radical scavengers are hydroxyphenylbenzotriazoles or sterically hindered amines (hindered amine light stabilizers, HALS). Examples of suitable free radical scavengers / UV stabilizers include, in particular, sterically hindered phenols and sterically hindered amines, which are referred to as HALS (hindered amine light stabilizers). The tetramethylpiperidine group present in HALS compounds is responsible for their stabilizing effect. These compounds can be unsubstituted or substituted with an alkyl or acyl group on the piperidine nitrogen. Stericly hindered amines do not absorb in the UV range. An example of hydroxyphenylbenzotriazole is 2-(2H-benzotriazole-2-yl)-p-cresol, which is marketed as Tinuvin® P or Drometrizole. They capture the free radicals formed, which again cannot be done by UV absorbers. The free radical scavenger / UV stabilizer is used in the composition according to the invention in an amount of 0.01% to 1.5% by weight, particularly 0.02% to 1.0% by weight, especially 0.02% to 0.5% by weight, based on the weight of the molding composition. Combinations of UV stabilizers / absorbers, light stabilizers, and antioxidants are also possible.

[0142] Lubricants and release agents that can reduce or completely prevent the molding composition from adhering to the injection mold are important for the injection molding process and can also be used. For example, lubricants selected from saturated fatty acids, esters, or inorganic salts having fewer than C20, preferably C16 to C18 carbon atoms, or saturated fatty alcohols having fewer than C20, preferably C16 to C18 carbon atoms, can be present as additives. Examples include stearic acid, stearyl alcohol, palmitic acid, palmitol, lauric acid, lactic acid, glyceryl monostearate, pentaerythritol, and industrial mixtures of stearic acid and palmitic acid. Also suitable are n-hexadecyl alcohol, n-octadecyl alcohol, and industrial mixtures of n-hexadecyl alcohol and n-octadecyl alcohol with glyceryl monostearate. A particularly preferred lubricant or release agent is stearyl alcohol. Based on the weight of the molding composition, the lubricant is typically used in an amount not exceeding 1.0% by weight, for example, from 0.05% to 0.25% by weight.

[0143] Uses of molding compositions and molded articles

[0144] The molding composition of the present invention can be processed into molded articles under normal processing conditions by any known common thermoplastic method, such as injection molding or extrusion. Injection molding of the composition can be carried out in a known manner at a temperature (melt temperature) in the range of 220°C to 280°C and preferably at a mold temperature of 60°C to 120°C. Extrusion is preferably carried out at a temperature of 220°C to 280°C.

[0145] Due to their high thermal stability and low haze, molding compositions and molded articles made from them are ideal for optical applications, such as lighting and mounting glass. Such applications include light guides, lenses, and mounting glass, such as glass covers for motor vehicle lamps (i.e., headlights or taillights); automotive lamp covers; and other diverse lighting applications for interior and / or exterior lighting of buildings, which must meet particularly high requirements regarding vandalism, thermal stability, and good processability.

[0146] The molding compositions of the present invention can be further advantageously used in optical discs or lenses, in communication devices, especially PDAs, mobile phones, preferably smartphones, for display or lighting components; tablet computers; TV devices; kitchen appliances and other electronic devices.

[0147] This invention relates to molded articles produced from the molding compositions of the present invention. In particular, the invention relates to molded articles produced from the molding compositions of the present invention as described above, wherein the molded articles are selected from display components (e.g., for communication devices, such as mobile phones, smartphones, tablets, TV devices, kitchen appliances); lighting components (e.g., light guides or lampshades, preferably for interior lighting systems or automotive lighting devices); automotive exterior components (e.g., lighting applications, sensor covers, design elements, black pillar trim, automotive lampshades); automotive interior components (e.g., lighting applications, sensor covers, design elements, instrument panels, automotive lampshades); optoelectronic device components (e.g., light-emitting diode (LED) components); optical sensor components; solar cell components; optical elements (e.g., optical lenses); and medical devices having a light source.

[0148] The invention is illustrated in more detail by the following embodiments. However, the invention is not intended to be limited to these embodiments. Detailed Implementation

[0149] Example

[0150] 1. Preparation of copolymer A

[0151] 1.1 Materials

[0152] Use the following starting materials:

[0153] MMA (methyl methacrylate), purity > 99.6%, from Röhm GmbH, Darmstadt, Germany.

[0154] Methyl acrylate (MA), purity > 99%, from Sigma Aldrich, St. Louis, USA.

[0155] 2-NB 2-norbornene, purity > 99.9%, from VWR International Merck

[0156] MAA methacrylic acid, purity > 99.6%, from Röhm GmbH, Darmstadt, Germany.

[0157] DDM n-dodecyl mercaptan, 98% purity, from Dr. Spiess Chemische Fabrik GmbH, Karlbach Jr., Germany.

[0158] Di-tert-amyl peroxide DTA, Luperox® DTA, from Sigma Aldrich, St. Louis, USA

[0159] 1.2 Copolymerization method and preparation of molding composition

[0160] Examples 1-5 (the present invention) and Example 6 (comparative) were carried out in an industrial-scale CSTR comprising a stirred stainless steel vessel. The polymerization was conducted at a predetermined temperature and a pressure above 10 bar. The polymerization conditions are summarized in Table 1 below.

[0161] Dodecyl mercaptan (DDM) was used as the chain transfer agent, and di-tert-amyl peroxide (DTA) was used as the free radical polymerization initiator. The composition of the reactor feed is described in Table 1 below. The component amounts given in Table 1 in weight % and mole % are based on the total molar amount of monomers.

[0162] To ensure steady-state operation, the reactor was run for approximately 6 hours before material samples were removed.

[0163] Table 1. Reactor feed composition and polymerization conditions for Examples 1-6

[0164]

[0165] Comparative Example

[0166] Total molarity based on monomers

[0167] The continuous copolymer solution from the CSTR is heated to 210°C in a heat exchanger downstream of the reactor, and then devolatile and granulated in a single-screw extruder to obtain copolymer granules.

[0168] 2. Test Results

[0169] The resulting granules were injection molded into 3 mm thick sheets at 250°C for the study of optical properties and the Vicat softening temperature (VST) B50, °C according to ISO 306. For all other tests, the granules were used directly.

[0170] The properties and composition of the resulting copolymers are summarized in Table 2 below. The composition of the copolymers is described below through... 1 Obtained by H-NMR.

[0171] Table 2 provides the amount of monomer units based on the total amount of copolymer.

[0172] Table 2: Composition and properties of copolymers in Examples 1-6

[0173]

[0174] Comparative Example

[0175] Al, Fe or Ni content

[0176] 3. Testing Methods

[0177] GPC Measurement Conditions

[0178] Molecular weight, Mw (weight-average molecular weight), Mn (number-average molecular weight), molecular weight distribution, and dispersion D (Mw / Mn) were determined using gel permeation chromatography (GPC) under the following test conditions.

[0179] Eluent: THF (HPLC grade) + 0.2 v / v TFA

[0180] Flow rate: 1 ml / min

[0181] Injection volume: 100 µl

[0182] Testing: RI HPS

[0183] Sample solution concentration: 2 g / L

[0184] Standard product: PMMA

[0185] Product properties

[0186] 3.0 mm thick specimens were prepared by injection molding at 250 °C and then stored at 23 °C and 50% relative humidity for 72 hours before measurement.

[0187] Haze (in [%)) was determined using a BYK Gardner Hazegard-plus haze meter according to ASTM D 1003 (1997). Optical transmittance (T, in [%)) was measured using a Varian Cary 5000 spectrophotometer according to ISO 13468-2 (2006). Yellowness index (YI) was measured using a Varian Cary 5000 spectrophotometer according to DIN 6167 (1980) (light source D65, 10° at a 3.0 mm layer thickness).

[0188] According to ISO 306-B50 (2014), the Vicat softening temperature (VST, in [°C]) is measured using a 3.0 mm thick specimen that has been stored at 105°C for 16 hours prior to measurement.

[0189] According to ISO 1133 (2011), the melt flow rate (MVR, in [ml / 10min]) is determined at 230 °C under a load of 3.8 kg.

[0190] copolymer composition

[0191] Recorded using a 400 MHz NMR spectrometer from Bruker 1 The composition of the copolymer was determined by H-NMR spectroscopy.

[0192] The determination of MAA units in the copolymer was performed by titration as described in WO 2022 / 122806 A1. The final copolymer contained less than 1% by weight of glutaric anhydride units, and this amount was included in the value of the MMA units.

[0193] After digestion of the copolymer, the contents of aluminum (Al), iron (Fe), and nickel (Ni) in the copolymer were determined by atomic absorption spectrometry (AAS). The content of each metal (Al, Fe, Ni) was less than 5 µg / g (=5 ppm) (copolymer).

Claims

1. A copolymer comprising a) 70.0 to 99.0 mol% of repeating units derived from methyl methacrylate; b) 1.0 to 30.0 mol% of repeating units of compounds represented by derivative free formula (I). (I) Wherein the substituent R 1 R 2 R 2a R 3 and R 3a Hydrocarbon groups that independently represent a hydrogen atom and have 1 to 12 carbon atoms; hydroxyl group; hydroxyalkyl group; carboxyl group; -C(=O)-NH2 group; -C(=O)-R group x ;-C(=O)-OR x ;where R x It is a C1-12-alkyl or C6-12-cycloalkyl; or R 2 and R 3 Together they can form a ring-shaped structure; and c) 0.0 to 15.0 mol% of repeating units derived from at least one optional comonomer c) selected from acrylic acid, methacrylic acid, vinyl aromatic monomers, alkyl acrylates and alkyl methacrylates other than methyl methacrylate; The weight-average molecular weight M of the copolymer, as determined by GPC, is... w The concentration is 40,000 to 300,000 g / mol, preferably 50,000 to 200,000 g / mol; Furthermore, based on the total copolymer, the sum of repeating units derived from methyl methacrylate, the compound represented by formula (I), and optional comonomer c) is at least 95.0 mol%, preferably at least 98.0 mol%.

2. The copolymer of claim 1, wherein the copolymer is obtained by free radical polymerization.

3. The copolymer according to claim 1 or 2, wherein the copolymer comprises less than 50 ppm, preferably less than 10 ppm, of a metal or metal compound based on the total copolymer and calculated by metal content, and involves a metal selected from transition metals and aluminum.

4. The copolymer according to any one of claims 1 to 3, wherein the copolymer contains less than 50 ppm, preferably less than 10 ppm, of a metal or metal compound based on the total copolymer and calculated by metal content, and relates to the sum of all metals present in the copolymer of the present invention.

5. The copolymer according to any one of claims 1 to 4, wherein the copolymer of the present invention comprises, based on the total copolymer and calculated by metal, less than 50 ppm, preferably less than 10 ppm, of a metal or metal compound, and relating to the sum of all metals present in the copolymer; wherein the copolymer of the present invention has a haze of less than 5.0%, preferably less than 3.0%, wherein the haze is measured at 23°C on an injection-molded specimen with a thickness of 3.0 mm prepared from the copolymer of the present invention according to standard ASTM D1003 (2013); and wherein the light transmittance T of the copolymer of the present invention is measured at 23°C on an injection-molded specimen with a thickness of 3.0 mm prepared from the copolymer of the present invention according to DIN 5033-7 (2014). D65 Within the range of 85% to 93%, more preferably within the range of 87% to 92.5%.

6. The copolymer according to any one of claims 1 to 5, wherein the compound represented by formula (I) is 2-norbornene.

7. The copolymer according to any one of claims 1 to 6, wherein the optional comonomer c) is at least one monomer selected from methacrylic acid, acrylic acid, methyl acrylate and ethyl acrylate.

8. The copolymer according to any one of claims 1 to 7, wherein the copolymer has a Vicat softening temperature of at least 105°C, preferably at least 110°C, according to ISO 306-B50 (2014).

9. The copolymer according to any one of claims 1 to 8, wherein the copolymer is a statistical copolymer or a random copolymer.

10. A method for producing the copolymer according to any one of claims 1 to 9, comprising: (a) A copolymerization step, comprising a monomer mixture including MMA, a monomer of formula (I), and optionally at least one optional comonomer (c) undergoing free radical copolymerization to form a copolymer, wherein the reaction temperature in copolymerization step (a) is above 100°C, preferably above 120°C, and wherein the monomer mixture comprises at least 10 mol%, preferably at least 20 mol%, of at least one monomer represented by formula (I) based on the total monomer mixture. (I) Wherein the substituent R 1 R 2 R 2a R 3 and R 3a Hydrocarbon groups that independently represent a hydrogen atom and have 1 to 12 carbon atoms; hydroxyl group; hydroxyalkyl group; carboxyl group; -C(=O)-NH2 group; -C(=O)-R group x ;-C(=O)-OR x ;where R x It is a C1-12-alkyl or C6-12-cycloalkyl; or R 2 and R 3 They can together form a ring-shaped structure.

11. The method according to claim 10, wherein the reaction temperature in copolymerization step (a) is in the range of 100°C to 200°C, preferably 120°C to 180°C.

12. The method according to claim 10 or 11, wherein the monomer mixture comprises at least one monomer represented by formula (I) in an amount of 10 to 70 mol% based on the total amount of polymerizable components, preferably 20.0 to 60.0 mol%.

13. The method according to any one of claims 10 to 12, wherein the monomer mixture in the copolymerization step (a), based on the total amount of polymerizable components, has the following composition: a) 30.0 to 90.0 mol%, preferably 40.0 to 80.0 mol% of methyl methacrylate; b) 10.0 to 70.0 mol%, preferably 20.0 to 60 mol%, of the compound represented by formula (I); and c) 0.0 to 15.0 mol%, preferably 0.0 to 10 mol%, of at least one optional comonomer c), selected from acrylic acid, methacrylic acid, vinyl aromatic monomers, alkyl acrylates and alkyl methacrylates other than methyl methacrylate.

14. The method according to any one of claims 10 to 13, wherein the copolymerization step (a) is performed as a bulk polymerization.

15. The method according to any one of claims 10 to 14, wherein the copolymerization step (a) is followed by (b) The step of heating the copolymer solution obtained in polymerization step (a) to a temperature of 100°C to 300°C, and (c) The step of removing volatile components in a degassing unit.

16. A molding composition comprising a copolymer according to any one of claims 1 to 9 and at least one additive selected from ultraviolet absorbers, ultraviolet stabilizers, antioxidants, colorants, flow improvers, scattering aids, lubricants, release agents, or any combination thereof.

17. A molded article produced from the molding composition of claim 16, wherein the molded article is selected from display components; lighting components; automotive exterior components; automotive interior components; optoelectronic device components; optical sensor components; solar cell components; optical elements; and medical device components having a light source.

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