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KR-20260066164-A - Methyl methacrylate-based copolymer and optical-grade molding composition containing the same

KR20260066164AKR 20260066164 AKR20260066164 AKR 20260066164AKR-20260066164-A

Abstract

The present invention relates to a copolymer based on methyl methacrylate and norbornene-type monomers with improved heat resistance, transparency, and haze value. Furthermore, the present invention relates to a molding composition comprising said copolymer and an easy method for manufacturing said copolymer through radical polymerization. The molding composition of the present invention is highly suitable for manufacturing molded articles that can be used as optical elements of various optical devices, for example, as light guides or lamp covers.

Inventors

  • 칼로프 뤼디거

Assignees

  • 룀 게엠베하

Dates

Publication Date
20260512
Application Date
20240910
Priority Date
20230920

Claims (17)

  1. Copolymer comprising the following: a) 70.0 to 99.0 mol% of repeating units derived from methyl methacrylate; b) 1.0 to 30.0 mol% of repeating units derived from the compound represented by the following chemical formula (I) [In the formula, substituents R1 , R2 , R2a , R3 , and R3a are independently represented by a hydrogen atom, a hydrocarbon group having 1 to 12 carbon atoms; a hydroxyl group; a hydroxyalkyl group; a carboxyl group; -C(=O) -NH2 ; -C(=O) -Rx ; -C(=O) -ORx (in the formula, Rx is a C1-12 -alkyl or C6-12 -cycloalkyl); or R2 and R3 may together form a cyclic portion]; and c) 0.0 to 15.0 mol% of repeating units derived from one or more optional comonomers selected from acrylic acid, methacrylic acid, vinyl aromatic monomers, alkyl acrylates, and alkyl methacrylates different from methyl methacrylate; Here, the weight-average molecular weight Mw of the copolymer measured by GPC is 40,000 to 300,000 g/mol, preferably 50,000 to 200,000 g/mol; And the sum of the repeating unit derived from methyl methacrylate, the repeating unit derived from the compound represented by chemical formula (I), and the repeating unit derived from an optional comonomer c) is 95.0 mol% or more, preferably 98.0 mol% or more, based on the total copolymer.
  2. In claim 1, the copolymer is a copolymer obtained by free radical polymerization.
  3. A 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 when calculated as metal, based on the total copolymer, for a metal selected from transition metals and aluminum.
  4. A copolymer according to any one of claims 1 to 3, wherein the copolymer comprises a metal or metal compound of less than 50 ppm, preferably less than 10 ppm, when calculated as metals based on the total copolymer and the sum of all metals present in the copolymer of the present invention.
  5. A copolymer according to any one of claims 1 to 4, wherein the copolymer of the present invention comprises, based on the total copolymer, a metal or metal compound of less than 50 ppm, preferably less than 10 ppm, when calculated as metals with respect to the sum of all metals present in the copolymer, and the haze of the copolymer of the present invention is less than 5.0%, preferably less than 3.0%, and the haze is measured at 23°C in an injection-molded specimen of 3.0 mm thickness made from the copolymer of the present invention according to the ASTM D1003 (2013) standard, and the light transmittance T D65 of the copolymer of the present invention is in the range of 85 to 93%, more preferably 87 to 92.5%, when measured at 23°C in an injection-molded specimen of 3.0 mm thickness made from the copolymer of the present invention according to the DIN 5033-7 (2014) standard.
  6. A copolymer according to any one of claims 1 to 5, wherein the compound represented by chemical formula (I) is 2-norbornene.
  7. A copolymer according to any one of claims 1 to 6, wherein optional comonomer c) is one or more monomers selected from methacrylic acid, acrylic acid, methyl acrylate, and ethyl acrylate.
  8. A copolymer according to any one of claims 1 to 7, wherein the copolymer has a Vicat softening temperature of 105°C or higher, preferably 110°C or higher, according to ISO 306-B50 (2014).
  9. A copolymer in which the copolymer is a statistical copolymer or a random copolymer, in any one of claims 1 to 8.
  10. A method for manufacturing a copolymer according to any one of claims 1 to 9, comprising the following steps: (a) a copolymerization step of forming a copolymer through radical copolymerization of a monomer mixture comprising MMA, a monomer of the following formula (I), and optionally one or more optional comonomers c); in the copolymerization step (a), the reaction temperature is greater than 100 °C, preferably greater than 120 °C, and the monomer mixture comprises at least 10 mol%, preferably at least 20 mol%, of one or more monomers represented by formula (I) based on the total monomer mixture. [In the formula, substituents R1 , R2 , R2a , R3 , and R3a are independently represented by a hydrogen atom, a hydrocarbon group having 1 to 12 carbon atoms; a hydroxyl group; a hydroxyalkyl group; a carboxyl group; -C(=O) -NH2 ; -C(=O) -Rx ; -C(=O) -ORx (in the formula, Rx is a C1-12 -alkyl or C6-12 -cycloalkyl); or R2 and R3 may together form a cyclic portion].
  11. A method according to claim 10, wherein the reaction temperature of the copolymerization step (a) is in the range of 100 ℃ to 200 ℃, preferably 120 ℃ to 180 ℃.
  12. A method according to claim 10 or 11, wherein the monomer mixture comprises one or more monomers represented by formula (I) in an amount of 10 to 70 mol%, preferably 20.0 to 60.0 mol%, based on the total amount of polymerizable components.
  13. A method according to any one of claims 10 to 12, wherein the monomer mixture in the copolymerization step (a) has the following composition based on the total amount of polymerizable components: a) 30.0 to 90.0 mol% methyl methacrylate, preferably 40.0 to 80.0 mol%; b) 10.0 to 70.0 mol% of a compound represented by chemical formula (I), preferably 20.0 to 60 mol%; and c) 0.0 to 15.0 mol%, preferably 0.0 to 10 mol%, of one or more optional comonomers selected from acrylic acid, methacrylic acid, vinyl aromatic monomers, alkyl acrylates, methyl methacrylates, and other alkyl methacrylates.
  14. A method according to any one of claims 10 to 13, wherein the copolymerization step (a) is performed by bulk polymerization.
  15. A method according to any one of claims 10 to 14, wherein, after the copolymerization step (a), the following step is performed: (b) a step of heating the copolymer solution obtained in the polymerization step (a) to a temperature of 100 °C to 300 °C, and (c) Step of removing volatile components in a degassing device.
  16. A molding composition comprising a copolymer according to any one of claims 1 to 9 and one or more additives selected from a UV absorber, a UV stabilizer, an antioxidant, a colorant, a flow improver, a scattering aid, a lubricant, a demolding aid, or a combination thereof.
  17. A molded article manufactured from a molding composition according to claim 16, selected from display parts; lighting parts; automotive exterior parts; automotive interior parts; parts for optoelectronic devices; parts for optical sensors; parts for solar cells; optical elements; and parts for medical devices having a light source.

Description

Methyl methacrylate-based copolymer and optical-grade molding composition containing the same The present invention relates to a copolymer based on methyl methacrylate and norbornene-type monomers with improved heat resistance, transparency, and haze value. Furthermore, the present invention relates to a molding composition comprising said copolymer and an easy method for manufacturing said copolymer through radical polymerization. The molding composition of the present invention is highly suitable for manufacturing molded articles that can be used as optical elements of various optical devices, for example, as light guides or lamp covers. A copolymer composed of repeating units derived from methyl methacrylate (hereinafter MMA) is also referred to for convenience as polymethyl methacrylate (hereinafter PMMA), and is generally a transparent material with high weather resistance, particularly high resistance to solar ultraviolet rays. If necessary, the weather resistance of PMMA can be further improved by adding UV absorbers, stabilizers, and inhibitors. Therefore, PMMA is widely used in fields requiring high transparency, low turbidity, and excellent weather resistance. There is an increasing demand for polymers with particularly excellent heat resistance in optical applications. These applications include high-power LED light sources for indoor and outdoor use, where such polymers are utilized as light guides and optical lenses. To increase the light output of LEDs, optical elements are positioned very close to the LEDs. The operating temperature of the LED surface, particularly for so-called white high-power LEDs, can exceed 100°C or even reach 130°C. Therefore, it is important for materials used in these applications to possess high transparency, particularly low haze values, and high thermal stability. Furthermore, these materials must have excellent weather resistance and exhibit minimal yellowing even after prolonged exposure to solar radiation. Several copolymers containing methyl methacrylate (MMA) with enhanced thermal stability are described in the art. For example, WO 2022/122806 A1 describes copolymers of methyl methacrylate, (meth)acrylic acid, and optional comonomers and methods for their preparation, wherein these copolymers and molding compositions containing them must possess high heat resistance and low glutaric anhydride content. Additionally, WO 2021/219738 and WO 2017/097979 A1 describe copolymers of MMA and methacrylic acid and methods for their preparation. These copolymers generally exhibit a Vicat temperature of approximately 116 °C. To raise the Vicat temperature of these copolymers above 120 °C, the amount of methacrylic acid units must be increased. However, increasing the amount of methacrylic acid units leads to reduced processability and increased water absorption. Generally, moisture absorption lowers the Vicat softening temperature of polymers. In addition, 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 these copolymers and blends containing said copolymers. The transparency of these copolymers and blends is often insufficient for various optical applications. Another disadvantage is reduced weather resistance due to the presence of styrene. Imidated polyalkyl (meth)acrylates, such as polymethylmethacrylimide (PMMI), are known in the field of technology (e.g., WO 2009/135703 A1). Generally, PMMI exhibits high heat resistance, including a Vicat temperature of approximately 120°C or higher; however, the manufacturing process of these imidized polymers is complex and costly, and they are often unsuitable for various optical applications requiring high standards for optical properties such as transmittance and yellowing. Additionally, a disadvantage is that PMMI has a high water absorption rate due to the methacrylimide groups, which lowers the Vicat temperature of polymers or polymer blends with high moisture content. Radical copolymerization of norbornene and alkyl (meth)acrylates is known to present various difficulties. It has been reported that radical copolymerization of norbornene and methyl acrylate can be carried out by a solution polymerization method with a long reaction time of 20 hours (see Comparative Example 1, KR 2009/0020344 A). Additionally, radical copolymerization of norbornene and acrylate monomers such as methyl acrylate, tert-butyl acrylate, and acrylic acid using benzoyl peroxide as an initiator is described in the literature ["Copolymers of norbornene and its derivatives with acrylates-Promising materials for optoelectronics", Bykov, V. I. et al, Doklady Chemistry, 2011, Vol. 439, Part 2, pp. 227-229]. Literature RU 2 456 304 C2 describes the radical copolymerization of acrylate monomers, in particular methyl acrylate and norbornene. For example, a copolymer can be prepared by polymerizing a monomer mixture in which the ratio of norbornene to methyl acrylate monom