Acid-functionalized methyl methacrylate copolymers and acrylic resin compositions based thereon

Abstract

Articles are manufactured using acid-functionalized methyl methacrylate copolymers with high glass transition temperature and molecular weight. These articles have high light transmittance, low haze, high heat resistance, and high environmental stability, and can be used as optical protective films, zero-zero optical retardation films and compensation films, as well as illumination tubes and optical imaging lenses.

Description

Invention Field

[0001] This invention relates to high molecular weight, acid-functionalized methyl methacrylate copolymers having a desired combination of properties, including high heat resistance, high transparency, low haze, tunable optical phase retardation, high environmental stability, and / or low hygroscopicity.

[0002] Discussion of related technologies

[0003] Cellulose triacetate (TAC) films are commonly used in laminates containing I2-dyed PVA (polyvinyl alcohol) absorbing polarizers. However, fabricating TAC / PVA-I2 / TAC laminates containing optical polarizers and meeting the requirements for high-temperature and high-humidity conditions (e.g., 85°C and 85% relative humidity) or for use with thinner optical polarizers presents challenges. Furthermore, TAC films exhibit a higher inherent effective negative optical retardation along their thickness and bevel directions, making them unsuitable for coplanar conversion (IPS) and / or edging field switching (FFS) liquid crystal (LCD) applications.

[0004] Therefore, there is a need for materials that can be used to manufacture improved films with tunable birefringence / optical phase retardation properties. Such films can be used as optical protective films, zero-zero retardation films, and optical compensation films in optical polarizers used in organic light-emitting diode (OLED), FFS, and IPS LCD devices, such as smartphones, tablets, laptops, and LCD televisions with LED light-emitting units. Furthermore, related acrylic materials can also be used in LED light-emitting diodes, light guide plates, optical imaging lenses, and other types of products. Invention Overview

[0005] This invention provides acrylic copolymers (including trimers and tetramers) containing acid functional groups that have high glass transition temperatures (e.g., T). g For the agreement 115With a temperature range of -145°C and a sufficiently high molecular weight (MW), high-Tg acrylic materials can be used to produce optical-grade products such as optical films, long-path light-emitting diodes, thin light guides, and optical imaging lenses. High-Tg acrylic materials can be designed to meet one or more of the following requirements: high heat resistance, high light transmittance, low haze, lower hygroscopicity, excellent dimensional stability, excellent mechanical properties, and optionally, excellent UV resistance. These acrylic copolymers can have a refractive index of 1.45-1.53 ​​at a wavelength of 589 nm. Acrylic copolymers can be synthesized using methods such as bulk polymerization, melt polymerization, emulsion polymerization, solution polymerization, and even suspension polymerization. The weight-average molecular weight of the acrylic copolymers is higher than 60,000 g / mol, preferably higher than 80,000 g / mol, more preferably higher than 90,000 g / mol, and even more preferably higher than 100,000 g / mol. The Tg value of the acrylic copolymers is higher than... 115 The temperature is preferably above 120°C, more preferably above 130°C. Furthermore, selected antioxidants can be combined with acrylic copolymers to provide acrylic resin compositions with improved thermal stability at high temperatures (e.g., 250-280°C), such that the acrylic copolymers do not exhibit significant yellowing or bubbling under these conditions. The antioxidant content in the final resin formulation can range from 0.01% to 4% by weight. A UV stabilizer at a content of 0.1-5% by weight can be used to further improve the UV resistance of the acrylic copolymers without significant loss of optical properties. Toughening agents, such as core-shell toughening agents and / or block copolymer toughening agents, can also be blended with high-Tg acrylic copolymers to provide acrylic resin compositions with improved mechanical toughness. 3.2 mm thick sheets prepared using the acrylic copolymers and acrylic resin compositions of the present invention can have a transmittance value higher than 89% (preferably higher than 91%) (measured according to ASTM D1003) and / or exhibit an optical haze value of less than 10% (preferably less than 2%).

[0006] Various non-limiting aspects of the present invention can be summarized as follows:

[0007] Aspect 1: A copolymer of methyl methacrylate, methacrylic acid and optionally at least one additional comonomer having a weight-average molecular weight of at least 60,000 g / mol and a glass transition temperature of at least 115 °C.

[0008] Aspect 2: The copolymer described in aspect 1, having a weight-average molecular weight of at least 80,000 g / mol.

[0009] Aspect 3: The copolymer described in aspect 1, having a weight-average molecular weight of at least 90,000 g / mol.

[0010] Aspect 4: The copolymer described in aspect 1, having a weight-average molecular weight of at least 100,000 g / mol.

[0011] Aspect 5: The copolymer described in any one of Aspects 1-4, having a glass transition temperature of at least 120°C.

[0012] Aspect 6: The copolymer described in any one of Aspects 1-5, having a glass transition temperature of at least 130°C.

[0013] Aspect 7: The copolymer described in any one of Aspects 1-6 has a refractive index of 1.45-1.53 ​​at a wavelength of 589 nm.

[0014] Aspect 8: The copolymer of any one of Aspects 1-7, wherein the at least one additional comonomer is selected from the group consisting of: ethyl acrylate, methyl acrylate, styrene, α-methylstyrene, cycloaliphatic unsaturated anhydride, phenyl methacrylate, cyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, tert-butyl methacrylate, and combinations thereof.

[0015] Aspect 9: The copolymers described in any one of Aspects 1-8, wherein the copolymers are selected from the group consisting of: methyl methacrylate / methacrylic acid copolymers, methyl methacrylate / methacrylic acid / ethyl acrylate copolymers, methyl methacrylate / methacrylic acid / methyl acrylate copolymers, methyl methacrylate / methacrylic acid / tert-butylcyclohexyl methacrylate copolymers, methyl methacrylate / methacrylic acid / isobornyl methacrylate copolymers, methyl methacrylate / methacrylic acid / styrene copolymers, methyl methacrylate / methacrylic acid / styrene / maleic anhydride copolymers, methyl methacrylate / methacrylic acid / maleic anhydride / α-methylstyrene copolymers, methyl methacrylate / methacrylic acid / tert-butylcyclohexyl methacrylate copolymers / isobornyl methacrylate copolymers, methyl methacrylate / methacrylic acid / isobornyl methacrylate / phenyl methacrylate copolymers, methyl methacrylate / methacrylic acid / phenyl methacrylate / tert-butylcyclohexyl methacrylate copolymers, methyl methacrylate / methacrylic acid / tert-butylcyclohexyl methacrylate / tert-butyl methacrylate copolymers, and combinations thereof.

[0016] Aspect 10: The copolymer of any one of Aspects 1-9, wherein the copolymer contains about 1-7% by weight of methacrylic acid.

[0017] Aspect 11: The copolymer of any one of Aspects 1-10, wherein the copolymer contains about 70-99% by weight of methyl methacrylate.

[0018] Aspect 12: The copolymer of any one of Aspects 1-10, wherein the copolymer comprises about 79-99% by weight of methyl methacrylate, about 1-7% by weight of methacrylic acid and a total of 0-about 20% by weight of at least one additional comonomer.

[0019] Aspect 13: The copolymer described in any one of Aspects 1-12, wherein, when measured on a 3.2 mm thick sheet according to ASTM D1003, the copolymer has a light transmittance of at least about 88% and a haze of less than 10%.

[0020] Aspect 14: The copolymer described in any one of Aspects 1-12, wherein, when measured on a 3.2 mm thick sheet according to ASTM D1003, the copolymer has at least about 90% light transmittance and less than 5% haze.

[0021] Aspect 15: The copolymer of any one of Aspects 1-14, wherein the copolymer has a melt flow rate of about 0.3-2.5 g / 10 min at 230°C and 3.8 kg measurement conditions.

[0022] Aspect 16: An acrylic resin composition comprising at least one copolymer according to any one of aspects 1-15 and at least one antioxidant.

[0023] Aspect 17: An acrylic resin composition comprising at least one copolymer according to any one of aspects 1-16 and at least one antioxidant selected from the group consisting of: phosphite / ester antioxidants, phosphate / ester antioxidants, phosphonate / ester antioxidants, phosphine antioxidants, phenolic antioxidants, triazine trione antioxidants, and combinations thereof.

[0024] Aspect 18: An acrylic resin composition comprising at least one copolymer according to any one of aspects 1-17 and at least one UV stabilizer.

[0025] Aspect 19: An acrylic resin composition comprising at least one copolymer according to any one of aspects 1-18 and at least one UV stabilizer selected from the group consisting of: benzophenone UV stabilizer, benzotriazole UV stabilizer, hydroxyphenylbenzotriazole UV stabilizer, hydroxyphenyltriazine UV stabilizer, benzoxazinone UV stabilizer, and combinations thereof.

[0026] Aspect 20: An acrylic resin composition comprising at least one copolymer according to any one of aspects 1-19 and at least one toughening agent.

[0027] Aspect 21: The acrylic resin composition of aspect 20, wherein the at least one toughening agent comprises at least one toughening agent selected from the group consisting of: block copolymer toughening agents (specifically block copolymer toughening agents selected from the group consisting of: diblock and triblock copolymers containing polyacrylate soft blocks and one or two polymethyl methacrylate and / or polystyrene hard blocks) and core-shell toughening agents.

[0028] Aspect 22: An acrylic resin composition comprising at least one copolymer according to any one of aspects 1-21 and at least one additional polymer selected from the group consisting of: copolymers of methyl methacrylate and one or more C1-C4 alkyl acrylates.

[0029] Aspect 23: The acrylic resin composition of aspect 22, wherein the at least one additional polymer is a copolymer of methyl methacrylate and at least one comonomer selected from ethyl acrylate or methyl acrylate.

[0030] Aspect 24: The acrylic resin composition of aspect 22 or 23, wherein, based on the total weight of the copolymer and the additional polymer, the acrylic resin comprises about 25% to about 99.9% by weight of the copolymer and 0.1% to about 75% by weight of the additional polymer.

[0031] Aspect 25: An acrylic resin composition according to any one of Aspects 22-24, wherein the at least one additional polymer has a weight-average molecular weight of at least 100,000 g / mol.

[0032] Aspect 26: An acrylic resin composition according to any one of Aspects 22-24, wherein the at least one additional polymer has a weight-average molecular weight of at least 120,000 g / mol.

[0033] Aspect 27: An acrylic resin composition comprising at least one copolymer according to any one of aspects 1-26, wherein an anhydride ring structure is present.

[0034] Aspect 28: The acrylic resin composition of aspect 27, comprising according to 13 The anhydride ring structure of 0.5-2 wt% was determined by C NMR.

[0035] Detailed description of certain embodiments of the present invention

[0036] The acid-functionalized acrylic copolymers of the present invention can be used to prepare acrylic resin compositions having a Tg of at least about 115°C (in other embodiments, at least 115°C, at least 120°C, at least 125°C, or at least 130°C; in some embodiments, the Tg of the acrylic resin composition is not greater than 140°C or not greater than 135°C) and a weight-average molecular weight of at least about 60,000 g / mol (in other embodiments, at least about 60,000 g / mol, at least about 70,000 g / mol, at least about 80,000 g / mol, at least about 90,000 g / mol, at least about 95,000 g / mol, or at least about 100,000 g / mol). In other embodiments, the acrylic resin composition has a weight-average molecular weight of not more than 250,000 g / mol or not more than 200,000 g / mol. Such acrylic resin compositions may comprise: a) a copolymer of at least one methyl methacrylate, methacrylic acid, and optionally at least one additional comonomer (hereinafter referred to as "methyl methacrylate and methacrylic acid copolymer" or "acid-functionalized acrylic copolymer") and optionally b) at least one additional polymer selected from the group consisting of: methyl methacrylate and one or more C1-C4 alkyl acrylates (hereinafter referred to as "optional additional polymer"). Acrylic resin compositions prepared with acid-functionalized acrylic copolymers may have at least about 88% or at least about 90% transmittance and less than about 10% or less than about 5% haze (measured according to ASTM D1003 on a 3.2 mm thick acrylic resin composition sheet), making them particularly suitable for manufacturing optical films, light guides, etc. The acrylic resin composition may additionally contain at least one antioxidant, such as antioxidants selected from the group consisting of: phosphite / ester antioxidants, phosphate / ester antioxidants, phosphonate / ester antioxidants, phosphine antioxidants, phenolic antioxidants, triazine trione antioxidants, and combinations thereof.

[0037] Analysis and testing methods

[0038] The examples describe test methods for measuring parameters and properties of the copolymer and acrylic resin composition according to the present invention, including, for example, glass transition temperature (Tg), weight-average molecular weight, % transmittance, and % haze.

[0039] A copolymer of methyl methacrylate and methacrylic acid (acid-functionalized acrylic copolymer)

[0040] As described above, one aspect of the present invention provides at least one copolymer of methyl methacrylate, methacrylic acid, and optionally at least one additional comonomer (hereinafter referred to as a "polymer of methyl methacrylate and methacrylic acid" or an "acid-functionalized acrylic copolymer"). In a preferred embodiment of the invention, the copolymer of methyl methacrylate and methacrylic acid is random (statistical copolymer). In another preferred embodiment, the copolymer of methyl methacrylate and methacrylic acid is linear (unbranched) copolymer.

[0041] Preferably, the at least one copolymer of methyl methacrylate and methacrylic acid is selected from the group consisting of: methyl methacrylate / methacrylic acid copolymer, methyl methacrylate / methacrylic acid / ethyl acrylate copolymer, methyl methacrylate / methacrylic acid / methyl acrylate copolymer, methyl methacrylate / methacrylic acid / tert-butylcyclohexyl methacrylate copolymer, methyl methacrylate / methacrylic acid / isobornyl methacrylate, methyl methacrylate / methacrylic acid / styrene copolymer, methyl methacrylate / methacrylic acid / styrene / maleic anhydride copolymer, methyl methacrylate / methacrylic acid / maleic anhydride / α-methylstyrene copolymer, methyl methacrylate / methacrylic acid / ethyl acrylate / methacrylic acid Benzyl acrylate copolymers, methyl methacrylate / methacrylic acid / benzyl methacrylate / tert-butylcyclohexyl methacrylate copolymers, methyl methacrylate / methacrylic acid / tert-butylcyclohexyl methacrylate copolymers / isoborneol methacrylate copolymers, methyl methacrylate / methacrylic acid / benzyl methacrylate / isoborneol methacrylate copolymers, methyl methacrylate / methacrylic acid / α-methylstyrene / n-butyl acrylate copolymers, methyl methacrylate / methacrylic acid / styrene / α-methylstyrene copolymers, methyl methacrylate / methacrylic acid / tert-butylcyclohexyl methacrylate / benzyl methacrylate copolymers, methyl methacrylate / methacrylic acid / isoborneol methacrylate / tert-butyl methacrylate copolymers, and combinations thereof.

[0042] In some embodiments, methacrylic acid (i.e., repeating units obtained by polymerizing methacrylic acid) may comprise at least about 0.5% by weight and / or no more than about 10% by weight of the copolymer, for example, about 1-7% by weight of the copolymer. According to other embodiments, methyl methacrylate (i.e., repeating units obtained by polymerizing methyl methacrylate) may comprise at least about 50% by weight and / or no more than about 99.5% by weight of the copolymer, for example, about 80-99% by weight. In various embodiments of the invention, the copolymer comprises about 79-99% by weight of methyl methacrylate, about 1-7% by weight of methacrylic acid, and a total of 0-about 20% by weight of at least one additional comonomer.

[0043] One or more optional additional comonomers used to prepare the copolymer can be any monomer capable of copolymerizing with methyl methacrylate and methacrylic acid, but in a preferred embodiment, they are vinyl aromatic monomers and / or (meth)acrylate monomers, such as (but not limited to) methyl acrylate, ethyl acrylate, styrene, cycloaliphatic unsaturated anhydrides (such as maleic anhydride), α-methylstyrene, cyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, tert-butyl methacrylate, n-butyl acrylate, phenyl methacrylate, and combinations thereof. Acrylic acid and other α-β-unsaturated carboxylic acid monomers may also be used. Other available comonomers include vinyl esters, such as neodecanoate and neovinyl nonanoate. Generally, it is desirable to utilize additional comonomers containing only a single polymerizable group (e.g., a carbon-carbon double bond) per molecule.

[0044] Specific examples of acid-functionalized acrylic copolymers according to the present invention include the following copolymers:

[0045] A copolymer composed of methyl methacrylate (92-98.5% by weight) and methacrylic acid (1.5-8% by weight);

[0046] A copolymer composed of methyl methacrylate (70-80% by weight), methacrylic acid (1-3% by weight), α-methylstyrene (20-25% by weight) and n-butyl acrylate (0.5-2% by weight);

[0047] A copolymer composed of methyl methacrylate (94-98 wt%, e.g., 96 wt%), methacrylic acid (1.0-4.5 wt%, e.g., 3 wt%) and parabens (0.5-4 wt%, e.g., 1 wt%).

[0048] A copolymer composed of methyl methacrylate (84-94 wt%), methacrylic acid (2-6 wt%), and styrene (2-10 wt%);

[0049] A copolymer consisting of methyl methacrylate (92-96 wt%, e.g., 94 wt%), methacrylic acid (2-4 wt%, e.g., 3 wt%), styrene (1-3 wt%) and optional α-methylstyrene (0-2 wt%);

[0050] A copolymer consisting of methyl methacrylate (92-96 wt%, e.g., 94 wt%), methacrylic acid (2-4 wt%, e.g., 3 wt%), optional ethyl acrylate (0-1 wt%) and optional isobornyl methacrylate (0-5 wt%).

[0051] A copolymer consisting of methyl methacrylate (92-96 wt%, e.g., 94 wt%), methacrylic acid (1-4 wt%, e.g., 3 wt%), optional ethyl acrylate (0-1 wt%) and optional tert-butylcyclohexyl methacrylate (0-5 wt%).

[0052] A copolymer consisting of methyl methacrylate (92-96 wt%, e.g., 94 wt%), methacrylic acid (1-4 wt%, e.g., 3 wt%), optional ethyl acrylate (0-1 wt%) and optional tert-butyl methacrylate (0-5 wt%).

[0053] Acid-functionalized acrylic copolymers can be prepared by adapting any technique known in the polymer field for copolymerizing acrylic monomers and other olefinically unsaturated monomers, such as bulk polymerization, melt polymerization, emulsion polymerization, solution polymerization, and suspension polymerization. For example, in bulk polymerization, a monomer mixture containing methyl methacrylate, methacrylic acid, and any other comonomers desired to be incorporated as part of the target acid-functionalized acrylic copolymer can be charged into a suitable polymerization reactor and the polymerization reaction initiated with a suitable initiator or combination of initiators such as a free radical initiator (e.g., a peroxide). One or more chain transfer agents, such as thiols and / or disulfides, may be additionally present. The polymerization reaction mixture is then heated at a temperature and time sufficient to achieve the desired degree of conversion, and any unreacted monomers are removed from the copolymer by any suitable means, such as evaporation.

[0054] The resulting copolymer can be compounded with one or more other components (e.g., additional polymers, toughening agents (e.g., block copolymer toughening agents, core-shell toughening agents), UV stabilizers and / or antioxidants) using any suitable method (e.g., extrusion) to obtain an acrylic resin composition.

[0055] Acrylic resin composition

[0056] Acrylic resin compositions containing copolymers of methyl methacrylate and methacrylic acid constitute other aspects of the present invention. Suitable acrylic resin compositions may, in addition to containing one or more copolymers of methyl methacrylate and methacrylic acid, contain one or more additional components of the following types: additive polymers, antioxidants, toughening agents (such as block copolymers and core-shell toughening agents), and / or UV stabilizers.

[0057] Optional additional polymers

[0058] As described above, in some embodiments of the invention, in addition to acid-functionalized acrylic copolymers, the acrylic resin composition contains at least one additional polymer. The additional polymer may be selected from the group consisting of copolymers of methyl methacrylate and one or more C1-C4 alkyl esters of acrylic acid. The additional polymer differs from the copolymer of methyl methacrylate and methacrylic acid in that it does not contain methacrylic acid. Therefore, the additional polymer may consist essentially of, or be composed of, polymeric units of methyl methacrylate and one or more C1-C4 alkyl esters of acrylic acid (C1-C4 alkyl esters of acrylic acid). In a preferred embodiment of the invention, the additional polymer is a random (statistical copolymer). In another preferred embodiment, the additional polymer is a linear (unbranched) copolymer.

[0059] For example, the at least one additional polymer may be a copolymer of methyl methacrylate and at least one comonomer selected from ethyl acrylate or methyl acrylate.

[0060] In a preferred embodiment of the invention, the at least one additional polymer may have a weight-average molecular weight of at least 100,000 g / mol, at least 110,000 g / mol, at least 120,000 g / mol, or at least 130,000 g / mol. In some embodiments, the weight-average molecular weight of the at least one additional polymer is not greater than 250,000 g / mol or not greater than 200,000 g / mol.

[0061] The additional polymer can be obtained by any polymerization method known in the art, such as melt polymerization, emulsion polymerization, emulsion polymerization or even suspension polymerization.

[0062] The additional polymer is not an essential component in the acrylic resin composition of the present invention. Therefore, in some embodiments of the present invention, based on the total weight of a) and b), the acrylic resin composition comprises about 25-100% by weight of a copolymer of methyl methacrylate and methacrylic acid and 0-about 75% by weight of the additional polymer.

[0063] In a preferred embodiment, one or more polymers used in the acrylic resin composition are selected to provide an acrylic resin composition having a melt flow rate of about 3-25 g / 10 min at 240°C and 10 kg.

[0064] In some embodiments of the present invention, the acrylic resin composition contains an anhydride ring structure. For example, the acrylic resin composition may contain, according to... 13The anhydride ring structure was determined by C18 NMR at 0.5–2% by weight. This anhydride ring structure can be incorporated into copolymers of methyl methacrylate and methacrylic acid, into additional polymers, or simultaneously into both, by using one or more comonomers containing anhydrides (especially anhydride-functionalized monomers containing carbon-carbon double bonds, such as maleic anhydride) during polymerization. The anhydride ring structure can also be incorporated post-polymerization by grafting or other polymer-derived methods known in the art.

[0065] antioxidants

[0066] Acrylic resin compositions may contain one or more antioxidants. In one embodiment, when the weight-average molecular weight of the polymer component of the acrylic resin composition is less than 90,000 g / mol, at least one antioxidant is present in the acrylic resin composition. Suitable antioxidants include those selected from the group consisting of: phosphite / ester antioxidants, phosphate / ester antioxidants, phosphonate / ester antioxidants, phosphine antioxidants, phenolic antioxidants (particularly sterically hindered phenolic antioxidants), triazine trione antioxidants, and combinations thereof.

[0067] Suitable examples of sterically hindered phenolic antioxidants include, but are not limited to, pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (produced by BASF under the trade name Irganox). ® 1010 sold), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (produced by BASF under the trade name Irganox) ® 1076 (sold) and triethylene glycol di(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate (produced by BASF under the trade name Irganox) ® 245 sales). Suitable examples of phosphites include, but are not limited to, pentaerythritol diphosphite, such as those described in U.S. Patent Nos. 5,364,895 and 5,438,086 (the contents of each of the disclosures are incorporated herein by reference in their entirety); pentaerythritol di(2,4-di-tert-butylphenol) diphosphite (produced by BASF under the trade name Irgafos). ® 126 sold), tris(2,4-di-tert-butylphenyl) phosphite (produced by BASF under the trade name Irgafos) ® 168 (sold) and pentaerythritol di(2,4-dicumylphenyl) bisphosphate [produced by Dover Chemical Corporation under the trade name DoverPhos] ® S-9228 sales).

[0068] In various embodiments of the present invention, the acrylic resin composition contains a total of about 150-4500 ppm or about 0.015-0.45% by weight of an antioxidant.

[0069] Other additives:

[0070] In addition to the various components mentioned above, acrylic resin compositions may optionally contain one or more additives. Suitable types of additional optional additives include, but are not limited to, fillers, colorants, pigments, lubricants, processing aids, toughening agents, and antistatic agents, provided that the amount of such additives does not interfere with the ability to obtain acrylic resin compositions with the desired transparency, clarity, and heat resistance properties.

[0071] In one embodiment, the acrylic resin composition additionally comprises at least one UV stabilizer. For example, suitable UV stabilizers may be selected from the group consisting of: benzophenone UV stabilizers, benzotriazole UV stabilizers, hydroxyphenylbenzotriazole UV stabilizers, hydroxyphenyl triazine UV stabilizers, benzoxazinone UV stabilizers, and combinations thereof. Specific examples of suitable UV stabilizers include, but are not limited to, 2-(2H-benzotriazole-2-yl)-4,6-di(1-methyl-1-phenylethyl)phenol (trade name Tinuvin by BASF). ® 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]phenol (sold by BASF under the trade name Tinuvin) ® 1577 (sold) and 2,2'-methylenebis(6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl))phenol (sold by BASF under the trade name Tinuvin) ® (360 sales) and combinations thereof. In some embodiments, the acrylic resin composition contains a total of about 0.1-5% by weight of UV stabilizer.

[0072] In another embodiment, the acrylic resin composition additionally includes at least one toughening agent (sometimes also referred to as an impact modifier). The choice of toughening agent is not limited and may include block copolymers and core-shell toughening agents. For example, suitable block copolymer toughening agents include block copolymers selected from the group consisting of diblock and triblock copolymers containing polyacrylate soft blocks and one or two polymethyl methacrylate and / or polystyrene hard blocks. Such block copolymers typically contain about 20-40% by weight of polybutyl acrylate blocks. Block copolymer toughening agents suitable for use in this invention may be obtained, for example, from Arkema under the brand name "Nanostrength".

[0073] Any core-shell toughening agent of any type known in the art can be used. The core-shell toughening agent can be in the form of fine particles having an elastomeric core and at least one thermoplastic shell, with a particle size generally less than 1 micrometer, preferably between 50-500 nm, and more preferably 100-450 nm. The core-shell toughening agent is typically a copolymer, which can be monodisperse or polydisperse. For example, for the core, isoprene homopolymers or butadiene homopolymers, copolymers of isoprene with up to 3 mol% of vinyl monomers, and copolymers of butadiene with up to 35 mol% and preferably 30 mol% or less of vinyl monomers can be mentioned. The vinyl monomers can be styrene, alkylstyrene, acrylonitrile, or alkyl (meth)acrylates. Another series of cores consists of homopolymers of alkyl (meth)acrylates and copolymers of alkyl (meth)acrylates with up to 35 mol% and preferably 30 mol% or less of vinyl monomers. Preferably, the alkyl (meth)acrylate is butyl acrylate. The vinyl monomer can be styrene, alkylstyrene, acrylonitrile, butadiene, or isoprene. The copolymer core can be fully or partially crosslinked. A requirement is that at least a bifunctional monomer is added during the preparation of the core; these monomers can be selected from poly(meth)acrylates of polyols, such as dibutyl(meth)acrylate and trimethylolpropane trimethacrylate. Other bifunctional monomers can be, for example, divinylbenzene, trivinylbenzene, vinyl acrylate, and vinyl methacrylate. Unsaturated functional monomers can also be introduced during polymerization by grafting or as comonomers, thereby crosslinking the core. These unsaturated functional monomers include, for example, anhydrides of unsaturated carboxylic acids, unsaturated carboxylic acids, and unsaturated epoxides. For example, maleic anhydride, (meth)acrylic acid, and glycidyl methacrylate may be mentioned.

[0074] For example, the shell can be a styrene homopolymer, an alkylstyrene homopolymer, or a methyl methacrylate homopolymer, or a copolymer comprising at least 70 mol% of one of the aforementioned monomers and at least one comonomer selected from the other monomers, vinyl acetate, and acrylonitrile. Unsaturated functional monomers can be introduced during polymerization by grafting or as comonomers, thereby crosslinking the shell. These unsaturated functional monomers include, for example, anhydrides of unsaturated carboxylic acids, unsaturated carboxylic acids, and unsaturated epoxides. Maleic anhydride, (meth)acrylic acid, and glycidyl methacrylate are examples. For example, a core-shell copolymer (A) having a polystyrene shell and a core-shell copolymer (A) having a PMMA shell are examples. The shell may also contain functional groups or hydrophilic groups to aid dispersion and compatibility with different polymer phases. A core-shell copolymer (A) having two shells also exists, one formed of polystyrene and the other, on the outside, formed of PMMA. Preferably, the core comprises 70-90% by weight of the core-shell polymer, and the shell comprises 30-10% by weight.

[0075] If a toughening agent is added to the acrylic resin composition, it is preferable that the toughening agent is selected to provide an acrylic resin composition having high optical transparency, high impact resistance and / or high mechanical toughness / ductility.

[0076] Uses of acid-functionalized acrylic copolymers and acrylic resin compositions

[0077] Although acid-functionalized acrylic copolymers and acrylic resin compositions containing such acid-functionalized acrylic copolymers are generally suitable for any end application employing thermoplastic materials, they are particularly well-suited for the manufacture of films, as described in more detail below.

[0078] Articles prepared from compositions of acrylic copolymers and acrylic resins

[0079] The acid-functionalized acrylic copolymers and acrylic resin compositions of the present invention are thermoplastic materials that can be formed or shaped into articles of any desired geometry using any suitable technique known in the field of plastics, including, for example, sheets, rods, tubes, films, molded parts, laminates, etc.

[0080] The membrane prepared using the acid-functionalized acrylic copolymer and acrylic resin composition of the present invention can be formulated and manufactured to have a transmittance of at least about 88% and a haze of less than about 10%. In other preferred embodiments, the membrane has a transmittance of at least 95%, at least 92%, or even higher. In other embodiments, the membrane has a haze of less than 0.5%, or less than 0.2%.

[0081] Stretched films, particularly biaxial and / or uniaxial stretched films, can be prepared using the acid-functionalized acrylic copolymers and acrylic resin compositions of the present invention. Prior to biaxial stretching, the film may have a thickness of, for example, about 60-500 micrometers. After biaxial stretching, the film may have a thickness of, for example, about 10-200 micrometers or 15-80 micrometers.

[0082] The optical film may have a glass transition temperature greater than or equal to 120°C (measured by DSC in N2 at a heating rate of 10°C / min) or a Tg greater than or equal to 125°C. The refractive index at a wavelength of 589 nm can be controlled within the range of 1.49-1.53. The in-plane and out-of-plane retardation values ​​of the zero-zero retardation film are controlled to be 10 nm / equivalent 100 μm or less. The tensile strength and modulus are higher than 70 MPa and 3 GPa, respectively, while the tensile elongation is preferably greater than 7%, more preferably greater than 10%. The film does not exhibit significant stress whitening during lamination. This optical film has better moisture resistance and environmental stability. Furthermore, the acid-functionalized acrylic copolymer and acrylic resin composition of the present invention has other potential applications in lighting tubes, optical imaging lenses, optical compensation films, etc.

[0083] The optical imaging lens and illumination tube can be prepared in an injection molding apparatus [such as an injection molding apparatus manufactured by Sumitomo Corporation], wherein the acid-functionalized acrylic copolymer and acrylic resin composition of the present invention are heated at a barrel temperature of 220-260°C, optionally under N2 protection. The light guide plate can be produced by melt extrusion or injection molding at elevated temperatures. Prior to melt processing, the resin is preferably thoroughly dried in a drying oven at a temperature approximately 20°C lower than the resin's Tg.

[0084] Methods of manufacturing products

[0085] Suitable methods for forming the compositions of the present invention into useful articles include, but are not limited to, extrusion, injection molding, blow molding, compression molding, vacuum forming, rotational molding, solution casting, and combinations thereof.

[0086] In some embodiments of the invention, films are manufactured from acid-functionalized acrylic copolymers or acrylic resin compositions by extrusion (melt casting) or solution casting.

[0087] In the first step of the film-forming extrusion process, the aforementioned acrylic resin composition can be fed into an extruder, such as a small-scale casting film production line, operating at a set temperature, extruder screw speed, extruder die clearance setting, and extruder back pressure sufficient to convert the loaded material from a solid (e.g., granular or pellet) state to a molten state. The extrusion process is typically carried out at a temperature in the range of 240-280°C, preferably in an inert gas such as nitrogen. Adding one or more antioxidants to the acrylic resin composition is recommended to prevent material degradation at higher processing temperatures.

[0088] Subsequently, molten material is transferred to a film-forming die, for example, by a gear pump, and extruded from the die onto a support. This die can be any conventional film-forming die, such as a "T-die" or a "coat hanger die." The film is then cooled and shaped by solidifying the cast material on the support, preferably made of a material capable of withstanding the temperature of the cast melt without deformation or damage due to chemical changes. Once the solidification process has progressed to the point where the film is self-supporting, it can be peeled off the support for further processing. Specifically, the film is preferably subjected to subsequent film orientation treatment by mechanical stretching under the conditions given below. Mechanical stretching can be performed before or after the cooling process is complete during film formation.

[0089] After extrusion or casting, the resulting film can be uniaxially or biaxially stretched. For example, the film can be stretched in a stretching step, whereby it can be uniaxially stretched in the longitudinal or transverse direction, or biaxially stretched in both directions. In the case of biaxial stretching, the film can be stretched simultaneously in both directions, or sequentially in both directions, i.e., first longitudinally then transversely, or vice versa. Unidirectional (e.g., longitudinal) orientation produces a uniaxially oriented film. Similarly, orientation in two directions (e.g., longitudinal and transverse) produces a biaxially oriented film, regardless of whether the orientation in these two directions is performed simultaneously or in two separate steps.

[0090] Uniaxial or biaxial stretching can be performed using conventional tenter frames, such as pin tenters, clip tenters, or biaxial stretching tenters. If the film is on a support, the support must be flexible enough to allow for effective stretching while maintaining the mechanical stretching operation without breaking.

[0091] For example, stretching can be done at T g -20℃ to T g It is carried out at temperatures within the range of +40°C, for example at T g -10℃ to T g Within the range of +35℃, or within T g -5℃ to T g Within the range of +30℃, where T g The glass transition temperature refers to the temperature of the resin composition used to prepare the membrane.

[0092] The stretch ratio is defined as the proportion L s / L0, where L s L0 represents the length of the film in the stretching direction after stretching, while L0 is defined as the length of the film in the stretching direction before stretching. The stretching ratio is preferably in the range of 1.05 to 6.0 times, or 1.1 to 4.0 times, or 1.25 to 3.0 times.

[0093] Membrane stretching rate refers to the percentage of elongation (L) in the longitudinal or transverse direction per unit time. s -L0) / L0 x100%, which can be, for example, 0.01% / second to 200% / second, 0.1% / second to 50% / second, or 0.5% / second to 10% / second.

[0094] The stretching can be performed in a single step or in multiple steps, wherein the stretching conditions of each step can be the same or different, but in any case fall within the range of conditions specified above for each individual step. Each stretching step may optionally further include a heat setting step, wherein the stretched film is held under tension for a period of time, for example, in the range of 1 second to 3 minutes, at a temperature, for example, close to or above the glass transition temperature of the copolymer or acrylic resin composition.

[0095] In another embodiment, the membrane can be produced by solution casting or coating. Such methods are particularly suitable for forming thinner membranes, i.e., membranes with a thickness less than that easily achievable by extrusion / biaxial stretching techniques. Any solution casting or coating methods known in the art can be adapted for use in this invention. For example, an acrylic resin composition can be dissolved in a suitable volatile solvent or a combination of several volatile solvents, and the resulting solution can then be applied as a layer to the surface of a suitable substrate. The applied layer can then undergo a drying step, wherein the solvent is removed by suitable methods such as heating and / or applying a vacuum. The resulting membrane can then be separated from the substrate (and optionally stretched as described above) or remain on the substrate, depending on suitability for the specific desired end product.

[0096] Applications of molded products

[0097] Articles prepared using the copolymer and acrylic resin composition of the present invention can be found in many industrial fields, including, for example, the optical industry, transportation industry, electronics industry, machinery industry, electrical appliance industry, container industry, construction industry, medical and health industry, sports and leisure industry, cable industry, etc., especially the various properties of the copolymer and acrylic resin composition (e.g., high heat resistance, high transparency, low haze, adjustable optical phase retardation, high environmental stability and / or low moisture absorption) are considered desirable or advantageous for end applications.

[0098] For example, films prepared from the acid-functionalized acrylic copolymers or acrylic resin compositions of the present invention can be used to produce optical-grade products for which high transparency is required and which are maintained under mechanical stress over a wide temperature range.

[0099] Films containing acid-functionalized acrylic copolymers or acrylic resin compositions, whether “unoriented” or “oriented”, obtained by solution casting, melt casting or any other film-forming method, can be further laminated onto other optical films to form composite film structures. Specific examples of these film structures include, but are not limited to, polarizers, positive biaxial plates, negative biaxial plates, positive C plates, negative C plates and negative wavelength dispersive half-plates.

[0100] The resulting films are amorphous, highly transparent, and have low haze, exhibiting tunable birefringence / phase retardation properties, long-term durability, good mechanical stability, and compatibility with other commonly used materials for manufacturing optical components. Therefore, they are considered suitable for optical compensation in the production of optical components with controllable light polarization states.

[0101] Therefore, the film prepared from the acid-functionalized acrylic copolymer or acrylic resin composition of the present invention can be used in a polarizing plate, the polarizing plate comprising a polarizer and two transparent protective films disposed on both sides of the polarizer, wherein at least one of the protective films is a film comprising the acid-functionalized acrylic copolymer or acrylic resin composition.

[0102] Polarizers can be, for example, iodine-based polarizers, dye-based polarizers using dichroic dyes, or polyene-based polarizers. Iodine-based or dye-based polarizers are typically produced using PVA-based films, wherein the production process includes doping the PVA-based film, biaxially stretching the film, optionally fixing it, and drying it. PVA-based films are generally obtained by casting a solution or melt containing a polymer, wherein the polymer is obtained prior to the polymerization of a vinyl ester monomer (possibly using other olefinically unsaturated compounds as comonomers), followed by saponification of the ester functional groups. The film is doped before, during, or after biaxial stretching. Doping can be achieved, for example, by immersing the PVA-based film in a solution containing iodine-potassium iodide and / or a dichroic dye, which absorbs the iodine-potassium iodide and / or the dichroic dye, or by co-blending these dopants during the film casting stage. Uniaxial stretching can be performed as a wet process, in which the film is stretched in a warm or hot (30-90°C) aqueous bath, which may be a solution containing the aforementioned dopants; or as a dry process, in which the film is stretched in an air or inert gas atmosphere at a temperature, for example, in the range of 50-180°C. The stretching ratio is typically at least 4.0 times. Mechanical stretching imparts a unidirectional orientation to the iodine-doped PVA-based film, which gives the film a polarizing effect. Typically, the polarizer has a thickness in the range of 10-40 µm or 15-30 µm after stretching. In the fixation process, the material used to form the film is crosslinked; for example, this can be done by contacting the film with a boric acid solution. Drying of the polarizer is typically performed at a temperature, for example, in the range of 30-150°C.

[0103] The polarizing plate may include a transparent protective film other than an optical retardation film, which comprises the acid-functionalized acrylic copolymer or acrylic resin composition of the present invention. Such other transparent protective films are not particularly limited; for example, they may be cellulose acrylate films, such as TAC films, which are commercially available. The method of applying the film comprising the acid-functionalized acrylic copolymer or acrylic resin composition of the present invention and / or other transparent protective films to the polarizer to form the polarizing plate is not particularly limited. For example, they may be directly laminated or bonded to the polarizer.

[0104] Optionally, additional functional films may be applied between or on top of one or both of the polarizer and the protective film, wherein one or both of the protective films may be films comprising the acid-functionalized acrylic copolymers or acrylic resin compositions of the present invention. Other functional films may include, but are not limited to, antireflective films, light scattering films, transparent hard coatings, antistatic films, adhesive films, UV absorption films, or polarizing films.

[0105] If necessary, adhesives (especially pressure-sensitive or hot-melt adhesives) or bonding layers can be used to promote bonding between any two of the aforementioned films [i.e., polarizers, protective films (which may be films containing the acid-functionalized acrylic copolymers or acrylic resin compositions of the present invention), and one of the other functional films]. Preferably, during the in-line film lamination process, a UV-curable acrylic adhesive containing a polyfunctional acrylic urethane and a blend of it with other polyfunctional acrylic resins (which typically contain multiple (meth)acrylate functional groups that are reactive / polymerizable upon exposure to UV light) is used to laminate the PVA film onto the acrylic optical film.

[0106] Such films, or polarizing plates comprising at least one such film, can be used in LCD display devices. In one aspect, the present invention therefore relates to a liquid crystal display or forming apparatus comprising a film containing the acid-functionalized acrylic copolymer or acrylic resin composition of the present invention described above. Such a liquid crystal display typically comprises a liquid crystal cell and two polarizing plates, one polarizing plate disposed on each side of the liquid crystal cell, wherein at least one polarizing plate comprises at least one film containing the acid-functionalized acrylic copolymer or acrylic resin composition of the present invention. For example, a film containing the acid-functionalized acrylic copolymer or acrylic resin composition of the present invention can be used on the side of the polarizing plate facing the liquid crystal. Acrylic optical phase retardation films include zero-zero retardation films, C-plates, quarter-wavelength plates, and half-wavelength plates.

[0107] Other suitable end uses of the acid-functionalized acrylic copolymers or acrylic resin compositions of the present invention include, but are not limited to, DVD production, insert molding, use as outer layers for flat panel displays or LEDs, membrane switches, decals or transfer films, instrument panels, and smart cards. In one embodiment, a graphic design can be printed onto a film containing the acid-functionalized acrylic copolymer or acrylic resin composition of the present invention or made therefrom, and then the printed film can be applied to a substrate. For example, a film containing the acid-functionalized acrylic copolymer or acrylic resin composition of the present invention can be applied to a substrate surface by lamination or by using an adhesive or binding layer. Films containing acid-functionalized acrylic polymers can provide better adhesion for PVA layers.

[0108] Various embodiments have been described in this specification in a manner that allows for clear and concise writing; however, it should be understood that the various embodiments are intended to be combined or separated in various ways without departing from the invention. For example, it should be understood that all preferred features described herein apply to all aspects of the invention described herein.

[0109] In some embodiments, the invention described herein can be understood to exclude any elements that do not materially affect the essential novelty of the acid-functionalized acrylic copolymers or acrylic resin compositions of the present invention. Furthermore, in some embodiments, the invention can be interpreted to exclude any elements not specified herein.

[0110] While the invention has been illustrated and described herein with reference to specific embodiments, it is not intended to be limited to the details shown. Rather, various changes in detail may be made within the scope of the equivalents of the claims without departing from the invention.

[0111] Example

[0112] Test method:

[0113] Melt flow rate (MFR) measurement: The melt flow rate of the polymer was measured using an Instron Ceast MF30 instrument. Unless otherwise specified, the die temperature was controlled at 230°C, and the load unit weight was 3.8 kg. (The last sentence appears to be incomplete and possibly refers to a different measurement.) g Use dried pellets for 8 hours at a temperature close to 20°C below the minimum.

[0114] Gel permeation chromatography (GPC): Polymer molecular weight was measured using a Waters Alliance 2695 and a Waters differential refractometer 2410. The column was based on two PL gel-coated C-columns and a guard column (7.8 mm inner diameter × 30 cm, 5 µm). THF (HPLC grade) was selected as the solvent. The temperature was controlled at 35 °C. Calibration was performed using 10 polymethyl methacrylate standards. p The peak molecular weight is in the range of 550-1,677,000 g / mol.

[0115] Differential Scanning Calorimetry (DSC): During the second heating, the glass transition temperature of the acrylic polymers was measured in N2 at a heating rate of 10 °C / min using a TA instrument Q2000 DSC. The first heating was used to heat the sample to 170 °C at a rate of 10 °C / min, followed by cooling the sample to 0 °C at a rate of 10 °C / min. The sample weight was controlled within 5-10 mg.

[0116] Thermogravimetric analysis (TGA): The thermal decomposition temperature of acrylic polymers was measured using a TA instrument Q5000 TGA in N2 at a heating rate of 10 °C / min. The sample weight was controlled between 5 and 10 mg. The sample was pre-dried in a vacuum oven at 100 °C for 16 hours. Isothermal TGA measurements were performed using a TA instrument Q5000 TGA at a heating rate of 10-50 °C / min in N2 or air for a certain duration, such as 30-60 minutes, until the selected isothermal temperature was reached.

[0117] Total transmittance: The total transmittance of the film and / or plate samples was measured in transmission mode using a Perkin Elmer Lambda 950 equipped with a 150 mm integrating sphere. The selected UV / visible wavelength range was 200–800 nm in the UV / visible region.

[0118] Haze: The optical haze of the transparent film and / or plate samples was measured using BYK HazeGard Plus.

[0119] Tensile strength and elongation: The tensile strength, modulus, and elongation of the tensile specimens were evaluated using an Instrand 4202 crosshead at a crosshead speed of 5 mm / min. The tensile specimens were 6 inches long and 0.50 inches wide. The specimen thickness was 0.125 inches.

[0120] Biaxial stretching: 4-inch x 4-inch film samples were stretched using a Bruckner at a rate of 0.05% / s to 50% / s. The biaxial stretching temperature was close to the glass transition temperature or Tg-20℃ to Tg+35℃. The film thickness was controlled between 100-500µm.

[0121] In-plane and out-of-plane delay: The in-plane delay of the optical film was measured by transmission using an ellipsometry [JA Woollam Inc.] at a selected wavelength of 560 nm or the entire visible light wavelength range, while the out-of-plane delay was obtained at the same selected wavelength of 560 nm or the entire visible light wavelength range.

[0122] Example 1

[0123] This example illustrates the preparation of a high molecular weight copolymer of methyl methacrylate and methacrylic acid (pMMA-MAA, 94 / 6w / w). 9260g of methyl methacrylate and 700g of methacrylic acid were charged into a reaction vessel at approximately 0°C under N2 atmosphere, with mechanical stirring at 100 rpm. Additionally, 1.6g of Luperox... ®531 (from Arkema) was used as the initiator, and 38 g of n-dodecyl mercaptan [n-DDM, from Aldrich] was used as the chain transfer agent. The polymerization reaction occurred at 150 °C for 5 hours. When the conversion reached approximately 55%, residual monomers were removed by venting during the extrusion process. The resulting polymer was extruded through a single-screw extruder at a die temperature of 230 °C and a barrel temperature of 230–250 °C. Prior to granulation, the melt flow was passed through a water bath. The polymer was then granulated into resin pellets of 3–4 mm length and dried in a 100 °C oven for 8 hours. The melt flow rate of the polymer was measured to be 1.4 g / 10 min at 230 °C and 3.8 kg. The refractive index of the resulting polymer at 589 nm was measured to be 1.496.

[0124] 1 ¹H NMR confirmed that the obtained polymer had a pMMA / MAA (94 / 6 w / w) composition. The glass transition temperature of the resin was 127 °C, measured by DSC in N₂ at a heating rate of 10 °C / min. GPC determined the weight-average molecular weight (Mw) to be 88,500 g / mol and the Mw / Mn (polydispersity) to be 2.0. The transmittance at 560 nm was 91.6% measured using a Lambda 950, and the haze was 0.6% measured using a haze meter (BYK's Haze Gard Plus). The tensile modulus of the polymer was determined to be 3.4 GPa, with a tensile strength of 76 MPa and an elongation of 9%.

[0125] Example 2

[0126] This example illustrates the preparation of a high molecular weight copolymer of methyl methacrylate and methacrylic acid (pMMA-MAA, 98 / 2w / w). 9780g of methyl methacrylate and 200g of methacrylic acid were charged into a reaction vessel at approximately 0°C under N2 conditions, with mechanical stirring at 100 rpm. Additionally, 1.6g of Luperox... ® 531 (from Arkema) was used as the initiator, and 18 g of n-dodecyl mercaptan [n-DDM, from Aldrich] was used as the chain transfer agent. The polymerization reaction occurred at 150 °C for 5 hours. When the conversion reached 50%, residual monomers were removed through the venting system. The resulting polymer was extruded through a single-screw extruder at a die temperature of 230 °C and a barrel temperature of 230-250 °C. The melt flow was passed through a water bath before granulation. The polymer was then granulated into resin pellets of 3-4 mm in length and dried in a 100 °C oven for 8 hours. The melt flow rate of the polymer was measured to be 0.46 g / 10 min at 230 °C and 3.8 kg. The refractive index of the resulting polymer at 589 nm was measured to be 1.493.

[0127] 1 ¹H NMR confirmed that the obtained polymer had a pMMA / MAA (98 / 2 w / w) composition. The glass transition temperature of the resin was 122 °C, measured by DSC in N₂ at a heating rate of 10 °C / min. GPC determined the weight-average molecular weight (Mw) to be 145,000 g / mol and the Mw / Mn (polydispersity) value to be 2.2. The transmittance at 560 nm was 91.8% measured using a Lambda 950, and the haze was 0.7% measured using a haze meter (BYK's Haze Gard Plus). The tensile modulus of the test sample was 3.1 GPa, the tensile strength was 71 MPa, and the elongation was 10%.

[0128] Example 3

[0129] This example illustrates the preparation of a resin comprising a high molecular weight copolymer of methyl methacrylate and methacrylic acid (pMMA-MAA, 98 / 2 w / w) and an antioxidant (AO). 6 g of Irganox was extruded using a twin-screw extruder with a vacuum pump system. ® Main antioxidant and 3g Irgafos ® The secondary antioxidant was incorporated into 3000g of pMMA-MAA resin prepared according to Example 2. The die temperature was 230°C, the barrel temperature was 260°C, and the flow rate was 25kg / hour. Before granulation, the melt flow was passed through a water bath. The melt flow rate (MFR) of the dried resin was measured to be 0.45 g / 10min at 230°C and 3.8kg. The refractive index of the resulting polymer at 589nm was measured to be 1.493.

[0130] The glass transition temperature of the resin was measured to be 121 °C using DSC in N2 at a heating rate of 10 °C / min. The weight-average molecular weight (Mw) was 146,000 g / mol, and the Mw / Mn (polydispersity) ratio was 2.3, as determined by GPC. The transmittance at 560 nm was 91.5% using Lambda 950, and the haze was 1.1% using a haze meter (BYK's Haze Gard Plus). The resin had a tensile modulus of 3.2 GPa, a tensile strength of 74 MPa, and an elongation at break of 12%.

[0131] Example 4

[0132] This embodiment represents a preferred embodiment of the present invention, illustrating the preparation of a copolymer (pMMA-α-methylstyrene-MAA-BA) of methyl methacrylate, α-methylstyrene, methacrylic acid and n-butyl acrylate by emulsion polymerization, with a Tg of approximately 140°C.

[0133] A mixture of 440 g α-methylstyrene, 40 g methacrylic acid, 20 g n-butyl acrylate, 1500 g methyl methacrylate, and 8 g n-dodecyl mercaptan was prepared. Then, 2 g sodium dioctyl sulfosuccinate was dissolved in the monomer mixture. Under mechanical stirring, 3000 g deionized water and 3 g sodium dodecylbenzene sulfonate were added to a suitable reactor. The mixture in the reactor was heated to 70 °C and degassed with nitrogen for 30 minutes. 300 g of the monomer mixture was charged into a reactor, followed by the addition of 15 g of 2% sodium formaldehyde sulfoxylate. After 5 minutes, 15 g of 2% tert-butyl hydroperoxide was added to initiate the seed latex.

[0134] After the mixture reached 8% solids content (90% conversion), the remaining 1710g of monomer mixture was added to the reactor over 4 hours. Also over 4 hours, 85.5g of 2% tert-butyl hydroperoxide and 85.5g of 2% sodium formaldehyde sulfoxylate were added separately. After the monomers were added, the latex was cured at 70°C for 1 hour, then cooled, filtered, and freeze-dried before compounding. Compounding was performed using an 18mm twin-screw extruder at a die temperature of 230°C. The polymer was then granulated into resins with lengths of 3-4 mm and dried in a 110°C oven for 8 hours. The melt flow rate of the polymer was measured to be 0.35 g / 10min at 230°C and 3.8kg. The refractive index of the resulting polymer at 589nm was measured to be 1.521.

[0135] 1 ¹H NMR confirmed that the obtained polymer had a composition of pMMA / MAA / α-styrene / BA (75 / 2 / 22 / 1 w / w / w / w). The glass transition temperature of the resin was 138 °C, measured by DSC in N₂ at a heating rate of 10 °C / min. The weight-average molecular weight (Mw) of the resin was 144,000 g / mol, and the Mw / Mn (polydispersity) ratio was 2.6, determined by GPC. The transmittance was 90.4% at 560 nm using a Lambda 950 microscope, and the haze was 1.5% measured by a haze meter (BYK's Haze Gard Plus).

[0136] Example 5

[0137] Using a hot melt compounding process, 4500 g of pMMA-MAA (95 / 5) (a copolymer of 97 wt% methyl methacrylate and 3 wt% ethyl acrylate, with a weight-average molecular weight Mw of 145,000-150,000 g / mol) was blended with 1000 g of poly(MMA / α-methylstyrene / MAA / BA) prepared according to Example 4 and 4500 g of high MW pMMA / EA (97 / 3) (a copolymer of 97 wt% methyl methacrylate and 3 wt% ethyl acrylate, with a weight-average molecular weight Mw of 145,000-150,000 g / mol) at high temperature to further improve heat resistance, mechanical properties, and moisture resistance. Compounding was performed using a twin-screw extruder equipped with a venting system, with a die temperature of 230°C and a barrel temperature of 245°C, and a speed of 25 kg / h. The polymer was then granulated into resin pellets 3-4 mm long and dried in a 100°C oven for 8 hours. The melt flow rate of the polymer was measured to be 1.3 g / 10 min at 230°C and 3.8 kg. The refractive index of the obtained polymer at 589 nm was measured to be 1.496.

[0138] The glass transition temperature of the blended resin was measured to be 120 °C using DSC in N2 at a heating rate of 10 °C / min. The weight-average molecular weight (Mw) of the resin was 108,000 g / mol, and the Mw / Mn (polydispersity) ratio was 2.1, as determined by GPC. The transmittance at 560 nm was 90.5% using a Lambda 950 microscope, and the haze was 0.8% using a haze meter (BYK's Haze Gard Plus). The resin had a tensile modulus of 3.3 GPa, a tensile strength of 72 MPa, and an elongation at break of 8%.

Claims

1. An acrylic resin composition comprising: a) At least one copolymer of methyl methacrylate and methacrylic acid, said at least one copolymer having a weight-average molecular weight of at least 70,000 g / mol and a glass transition temperature of at least 120°C, and said at least one copolymer containing about 70-99% by weight of methyl methacrylate; b) At least one additional polymer having a weight-average molecular weight of at least 130,000 g / mol and selected from the group consisting of the following: A copolymer of methyl methacrylate and one or more C1-C4 alkyl acrylates, and c) An acrylic copolymer containing a styrene-based comonomer and a comonomer having acid functional groups, wherein the acrylic copolymer has a weight-average molecular weight of at least 140,000 g / mol. When measured on a 3.2 mm thick sheet according to ASTM D1003, the at least one copolymer has a light transmittance of at least about 90% and a haze value of less than 5%.

2. The acrylic resin composition according to claim 1, having a refractive index of 1.45-1.53 ​​at a wavelength of 589 nm.

3. The acrylic resin composition according to claim 1, further comprising at least one additional comonomer selected from the group consisting of: Ethyl acrylate, methyl acrylate, styrene, α-methylstyrene, cycloaliphatic unsaturated acid anhydrides, cyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, tert-butyl methacrylate, vinyl esters, vinyl decanoate, vinyl nonanoate, and combinations thereof.

4. The acrylic resin composition according to claim 1, wherein the at least one copolymer is selected from the group consisting of the following: methyl methacrylate / methacrylic acid / ethyl acrylate copolymers, methyl methacrylate / methacrylic acid / methyl acrylate copolymers and combinations thereof.

5. The acrylic resin composition according to claim 1, wherein the at least one copolymer contains about 1-7% by weight of methacrylic acid.

6. The acrylic resin composition according to claim 1, wherein the at least one copolymer comprises about 1-7% by weight of methacrylic acid and a total of 0-20% by weight of at least one additional comonomer.

7. The acrylic resin composition according to claim 1, wherein the at least one copolymer has a melt flow rate of about 0.3-2.5 g / 10 min under the conditions of 230°C and 3.8 kg measurement.

8. The acrylic resin composition according to claim 1, further comprising at least one antioxidant selected from the group consisting of: Phosphite / ester antioxidants, phosphate / ester antioxidants, phosphonate / ester antioxidants, phosphine antioxidants, phenolic antioxidants, triazine trione antioxidants, and combinations thereof.

9. The acrylic resin composition according to claim 1, further comprising at least one UV stabilizer.

10. The acrylic resin composition according to claim 9, wherein the at least one UV stabilizer is selected from the group consisting of the following: Benzyl ketone UV stabilizer, benzotriazole UV stabilizer, hydroxyphenylbenzotriazole UV stabilizer, hydroxyphenyltriazine UV stabilizer, benzoxazinone UV stabilizer, and combinations thereof.

11. The acrylic resin composition according to claim 1, wherein the at least one additional polymer is a copolymer of methyl methacrylate and at least one comonomer selected from ethyl acrylate or methyl acrylate.

12. The acrylic resin composition of claim 1, wherein the acrylic resin comprises about 25% to about 99.9% by weight of the at least one copolymer and 0.1% to about 75% by weight of the at least one additional polymer.

13. The acrylic resin composition according to claim 1, wherein an anhydride ring is present.

14. The acrylic resin composition according to claim 13, comprising, according to 13 0.5-2% by weight of acid anhydride ring as determined by C NMR.

15. The acrylic resin composition according to claim 1, wherein the acrylic polymer is selected from the group consisting of the following: methyl methacrylate / methacrylic acid / tert-butylcyclohexyl methacrylate copolymer, methyl methacrylate / methacrylic acid / isobornyl methacrylate copolymer, methyl methacrylate / methacrylic acid / styrene copolymer, methyl methacrylate / methacrylic acid / styrene / maleic anhydride copolymer, methyl methacrylate / methacrylic acid / maleic anhydride / α-methylstyrene copolymer, methyl methacrylate / methacrylic acid / ethyl acrylate / tert-butyl methacrylate copolymer and combinations thereof.