Resin compositions and optical components

Abstract

The present invention provides a resin composition that maintains high heat resistance and light transmittance while improving mechanical strength, and optical components using such a resin composition. [Solution] According to one aspect of the present invention, a resin composition is provided which contains copolymer (A) and copolymer (B) different from copolymer (A), wherein copolymer (A) contains two or more aromatic vinyl monomer units and (meth)acrylic acid ester monomers, copolymer (B) contains one aromatic vinyl monomer unit and (meth)acrylic acid ester monomers, the absolute difference between the content of aromatic vinyl monomer units in copolymer (A) and the content of aromatic vinyl monomer units in copolymer (B) is 25% by mass or less, and the absolute difference between the content of (meth)acrylic acid ester monomers in copolymer (A) and the content of (meth)acrylic acid ester monomers in copolymer (B) is 25% by mass or less.

Description

Technical Field

[0001] The present invention relates to a resin composition and an optical component.

Background Art

[0002] Molded articles of styrene-(meth)methyl acrylate copolymers are excellent in properties such as light transmittance (transparency), low water absorption, low specific gravity (low density), and moldability, and are therefore used in diffuser plates or light guide plates for displays (televisions, monitors), lighting, etc., optical components such as spectacle lenses, and miscellaneous goods such as cosmetic containers and cups. However, since styrene-(meth)methyl acrylate copolymers do not have sufficient heat resistance, their range of use is limited, and furthermore, improvement of heat resistance has been demanded due to the increased output of recent LEDs.

[0003] So far, copolymers excellent in heat resistance, light transmittance, etc. have been developed (see Patent Document 1), and this copolymer contains methyl methacrylate units, styrene units, and α-methylstyrene units in a predetermined ratio. However, although the above copolymer has high heat resistance, since the polymerization property of α-methylstyrene is low, it is difficult to obtain a high molecular weight copolymer with good productivity, and there is room for further improvement in terms of mechanical strength.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In view of the above circumstances, the present invention aims to provide a resin composition having improved mechanical strength while maintaining high heat resistance and light transmittance, and an optical component using such a resin composition.

Means for Solving the Problems

[0006] According to one aspect of the present invention, a resin composition is provided which contains copolymer (A) and copolymer (B) different from copolymer (A), wherein copolymer (A) contains two or more aromatic vinyl monomer units and (meth)acrylic acid ester monomers, and copolymer (B) contains one aromatic vinyl monomer unit and (meth)acrylic acid ester monomer, and the absolute difference between the content of aromatic vinyl monomer units in copolymer (A) and the content of aromatic vinyl monomer units in copolymer (B) is 25% by mass or less, and the absolute difference between the content of (meth)acrylic acid ester monomers in copolymer (A) and the content of (meth)acrylic acid ester monomers in copolymer (B) is 25% by mass or less.

[0007] According to this embodiment, it is possible to improve mechanical strength while maintaining high heat resistance and light transmittance. [Modes for carrying out the invention]

[0008] The following describes embodiments of the resin composition and optical components. The various features shown in the embodiments below can be combined with each other. <Resin composition> The resin composition of this embodiment contains copolymer (A) and copolymer (B) which is different from copolymer (A). Copolymer (A) has the function of imparting high heat resistance and excellent light transmittance (transparency) to the resin composition. On the other hand, copolymer (B) has the function of improving the light transmittance and mechanical strength of the resin composition without reducing the heat resistance imparted by copolymer (A).

[0009] Copolymer (A) contains two or more aromatic vinyl monomer units and a (meth)acrylic acid ester monomer, and copolymer (B) contains one aromatic vinyl monomer unit and a (meth)acrylic acid ester monomer. Furthermore, the absolute value (I) of the difference between the content of aromatic vinyl monomer units in copolymer (A) and the content of aromatic vinyl monomer units in copolymer (B) is approximately 25% by mass or less, and the absolute value (II) of the difference between the content of (meth)acrylic acid ester monomers in copolymer (A) and the content of (meth)acrylic acid ester monomers in copolymer (B) is approximately 25% by mass or less.

[0010] With this configuration, the difference in the content of aromatic vinyl monomer units and (meth)acrylic acid ester monomers between copolymer (A) and copolymer (B) can be reduced, that is, the difference in composition can be reduced. As a result, the compatibility between copolymer (A) and copolymer (B) can be improved, and therefore, the resulting resin composition can improve mechanical strength while maintaining high heat resistance and light transmittance. In this specification, the content (mass%) of each monomer unit in the copolymer is the amount when the entire copolymer is considered to be 100% by mass. Furthermore, in this specification, the content of each monomer unit is determined by preparing a sample by dissolving the copolymer in deuterated chloroform. 13 It is calculated using 1C-NMR, based on the area ratio of the spectral peaks attributable to each monomer unit.

[0011] The absolute value (I) above may be approximately 25% by mass or less, but is preferably approximately 20% by mass or less, more preferably approximately 15% by mass or less, even more preferably approximately 10% by mass or less, particularly preferably approximately 5% by mass or less, and may even be 0% by mass. Furthermore, the absolute value (II) above may be approximately 25% by mass or less, but is preferably approximately 20% by mass or less, more preferably approximately 15% by mass or less, even more preferably approximately 10% by mass or less, particularly preferably approximately 5% by mass or less, and may even be 0% by mass. In these cases, the above effects can be further enhanced. Copolymer (A) and copolymer (B) will be described below.

[0012] <<Copolymer (A)>> As described above, copolymer (A) contains two or more aromatic vinyl monomer units and (meth)acrylic acid ester monomers. Aromatic vinyl monomer units are constituent units of copolymers (A) derived from aromatic vinyl monomers used in copolymerization. Examples of aromatic vinyl monomer units for copolymer (A) include styrene units, o-methylstyrene units, m-methylstyrene units, p-methylstyrene units, 2,4-dimethylstyrene units, ethylstyrene units, p-tert-butylstyrene units, α-methylstyrene units, and α-methyl-p-methylstyrene units. Note that three or more aromatic vinyl monomer units may be used in combination.

[0013] Among these, the aromatic vinyl monomer units of copolymer (A) preferably include styrene units and α-methylstyrene units. By including styrene units as aromatic vinyl monomer units, the specific gravity of copolymer (A) can be reduced (and consequently, the specific gravity of the resin composition can be reduced). Therefore, the molded articles obtained from such resin compositions can be made lighter. Herein, in this specification, the density of the resin composition is a value measured in accordance with JIS K 7112-1:2023 (ISO 1183-1:2019). On the other hand, by including α-methylstyrene units as aromatic vinyl monomer units, the heat resistance of copolymer (A) can be sufficiently enhanced. In other words, copolymer (A) can be made into a so-called heat-resistant MS resin.

[0014] On the other hand, (meth)acrylic acid ester monomer units are constituent units of copolymers (A) derived from (meth)acrylic acid ester monomers used in copolymerization. Examples of (meth)acrylic acid ester monomer units of copolymer (A) include methacrylic acid ester units such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate, as well as acrylic acid ester units such as methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-methylhexyl acrylate, 2-ethylhexyl acrylate, and decyl acrylate. Note that one type of acrylic acid ester monomer unit may be used alone, or two or more types may be used in combination. Among these, the (meth)acrylic acid ester monomer unit of copolymer (A) preferably contains methyl methacrylate units. Including methyl methacrylate units as the (meth)acrylic acid ester monomer unit can enhance copolymerizability with styrene units.

[0015] Therefore, copolymer (A) preferably contains styrene units, methyl methacrylate units, and α-methylstyrene units. The styrene unit is a constituent unit of copolymers (A) derived from styrene used in copolymerization. The styrene unit content in copolymer (A) is preferably 5% to 40% by mass, more preferably 10% to 35% by mass, even more preferably 15% to 30% by mass, and particularly preferably 20% to 25% by mass. Including styrene units in such amounts can improve the rigidity and moldability of copolymer (A). Furthermore, the specific gravity of copolymer (A) can be sufficiently reduced.

[0016] The methyl methacrylate unit is a constituent unit of copolymer (A) derived from methyl methacrylate, which is used in copolymerization. The content of methyl methacrylate units in the copolymer (A) is preferably about 40% by mass or more and 80% by mass or less, more preferably about 45% by mass or more and 70% by mass or less, and even more preferably about 50% by mass or more and 60% by mass or less. By containing methyl methacrylate units in such amounts, the copolymerizability with styrene units can be further improved.

[0017] The α-methylstyrene unit is a structural unit of the copolymer (A) derived from α-methylstyrene used in the copolymerization. The content of α-methylstyrene units in the copolymer (A) is preferably about 5% by mass or more and 35% by mass or less, more preferably about 10% by mass or more and 30% by mass or less, and even more preferably about 15% by mass or more and 25% by mass or less. By containing α-methylstyrene units in such amounts, the heat resistance of the copolymer (A) can be further enhanced.

[0018] The copolymer (A) of the present embodiment may contain other copolymerizable monomer units other than styrene units, methyl methacrylate units, and α-methylstyrene units within a range that does not inhibit the effects of the copolymer (A). Examples of other copolymerizable monomer units include acrylic acid units, acrylonitrile units, methacrylonitrile units, butyl acrylate units, ethyl acrylate units, methyl acrylate units, phenylmaleimide units, cyclohexylmaleimide units, and the like. Note that other copolymerizable monomer units may be used alone or in combination of two or more. The content of other copolymerizable monomer units in the copolymer (A) is preferably about 0% by mass or more and 10% by mass or less, and more preferably about 0% by mass or more and 8% by mass or less.

[0019] In the copolymer (A) of the present embodiment, the total content of styrene units, methyl methacrylate units, and α-methylstyrene units is preferably more than 96% by mass, and more preferably 98% by mass or more. Furthermore, copolymer (A) may consist substantially only of styrene units, methyl methacrylate units, and α-methylstyrene units. Here, "consistently consisting only of styrene units, methyl methacrylate units, and α-methylstyrene units" means that it may contain units derived from other components, but only to the extent that the effects of copolymer (A) are not inhibited by units derived from other components.

[0020] Typically, the total content of styrene units, methyl methacrylate units, and α-methylstyrene units is preferably 99.5% by mass or more and 100% by mass or less. Furthermore, units derived from other components are not limited to those exemplified above as other copolymerizable monomer units. When two or more units derived from other components are used in combination, their content refers to the total amount of units derived from the other components used in combination. Furthermore, even when methacrylic acid monomer units are present, their content is preferably less than 4% by mass, and more preferably less than 2% by mass.

[0021] The weight-average molecular weight (Mw) of copolymer (A) is not particularly limited, but is preferably around 50,000 to 200,000, more preferably around 60,000 to 150,000, and even more preferably around 70,000 to 100,000. By using copolymer (A) having such a weight-average molecular weight, it is possible to achieve both the bending strength of the optical component made using the resin composition and the fluidity of the resin composition. In this specification, the weight-average molecular weight is a polystyrene-based value measured by gel permeation chromatography (GPC).

[0022] <<Copolymer (B)>> Copolymer (B), as described above, contains one type of aromatic vinyl monomer unit and a (meth)acrylic acid ester monomer. In other words, copolymer (B) is an MS resin. Preferably, the content of aromatic vinyl monomer units in copolymer (B) is 10% by mass or more and 90% by mass or less, and the content of (meth)acrylic acid ester monomer units is 10% by mass or more and 90% by mass or less. Copolymer (B), which contains aromatic vinyl monomer units and (meth)acrylic acid ester monomer units within the above range, has high compatibility with copolymer (A), making it easy to uniformly mix copolymer (A) and copolymer (B). Furthermore, the resulting resin composition maintains the high heat resistance and light transmittance provided by copolymer (A), while improving mechanical strength and thermal stability compared to copolymer (A) alone.

[0023] Aromatic vinyl monomer units are constituent units of copolymers (B) derived from aromatic vinyl monomers used in copolymerization. The aromatic vinyl monomer units of copolymer (B) are the same as those described for copolymer (A). Among these, styrene units are preferred. Copolymer (B) using styrene units as aromatic vinyl monomer units can have improved rigidity and moldability. Furthermore, the inclusion of styrene units makes it possible to lower the specific gravity of copolymer (B) (and consequently, the specific gravity of the resin composition). Therefore, the molded articles obtained from such resin compositions can be made lighter. In this embodiment, one type of aromatic vinyl monomer unit is used alone.

[0024] The content of aromatic vinyl monomer units is preferably 10% by mass or more and 90% by mass or less, more preferably 15% by mass or more and 80% by mass or less, even more preferably 20% by mass or more and 70% by mass or less, and particularly preferably 30% by mass or more and 60% by mass or less. By including aromatic vinyl monomer units in such amounts, the rigidity and moldability of copolymer (B) can be sufficiently enhanced.

[0025] (Meth)acrylic acid ester monomer units are constituent units of copolymers (B) derived from (meth)acrylic acid ester monomers used in copolymerization. The (meth)acrylic acid ester monomer units of copolymer (B) are the same units as those described for the (meth)acrylic acid ester monomer units of copolymer (A). Among these, methyl methacrylate units are preferred as the (meth)acrylic acid ester monomers. Copolymer (B) using methyl methacrylate units as the (meth)acrylic acid ester monomer units can improve light transmittance while preventing an increase in manufacturing costs. Furthermore, (meth)acrylic acid ester monomer units may be used individually or in combination of two or more types.

[0026] The content of (meth)acrylic acid ester monomer units is preferably 10% to 90% by mass, more preferably 15% to 80% by mass, even more preferably 20% to 70% by mass, and particularly preferably 30% to 60% by mass. By including (meth)acrylic acid ester monomer units in such amounts, the light transmittance of copolymer (B) can be sufficiently increased. Furthermore, when two or more (meth)acrylic acid ester monomer units are used in combination, the content of (meth)acrylic acid ester monomer units refers to the total amount of (meth)acrylic acid ester monomer units used in combination.

[0027] The copolymer (B) of this embodiment may contain other copolymerizable monomer units other than aromatic vinyl monomer units and (meth)acrylic acid ester monomer units, to the extent that they do not hinder the effects of copolymer (B). Other copolymerizable monomer units include, for example, acrylic acid units, acrylonitrile units, methacrylonitrile units, butyl acrylate units, ethyl acrylate units, methyl acrylate units, phenylmaleimide units, and cyclohexylmaleimide units. These other copolymerizable monomer units may be used individually or in combination of two or more. The content of other copolymerizable monomer units is preferably 0% by mass or more and 10% by mass or less, and more preferably 0% by mass or more and 8% by mass or less.

[0028] In copolymer (B) of this embodiment, the total content of aromatic vinyl monomer units and (meth)acrylic acid ester monomer units is preferably more than 96% by mass, and more preferably 98% by mass or more. Furthermore, copolymer (B) may be substantially composed only of aromatic vinyl monomer units and (meth)acrylic acid ester monomer units. Here, substantially composed only of aromatic vinyl monomer units and (meth)acrylic acid ester monomer units means that it may include units derived from other components, but only to the extent that the effect of copolymer (B) is not inhibited by units derived from other components other than aromatic vinyl monomer units and (meth)acrylic acid ester monomer units.

[0029] Typically, the total content of aromatic vinyl monomer units and (meth)acrylic acid ester monomer units is preferably around 99.5% by mass or more and 100% by mass or less. Furthermore, units derived from other components are not limited to those exemplified above as other copolymerizable monomer units. When two or more units derived from other components are used in combination, their content refers to the total amount of units derived from the other components used in combination. Furthermore, even when methacrylic acid monomer units are present, their content is preferably less than 4% by mass, and more preferably less than 2% by mass.

[0030] The weight-average molecular weight of copolymer (B) is not particularly limited, but is preferably around 70,000 to 300,000, more preferably around 100,000 to 300,000, even more preferably around 140,000 to 260,000, and particularly preferably around 180,000 to 220,000. By using copolymer (B) having such a weight-average molecular weight, it is possible to achieve both the bending strength of the optical component made using the resin composition and the fluidity of the resin composition.

[0031] The polymerization method for producing (synthesizing) copolymer (A) and copolymer (B) is not particularly limited, but radical copolymerization using an organic peroxide is preferred. Furthermore, a bulk continuous polymerization process using a small amount of solvent is preferred as the production process for copolymer (A) and copolymer (B). The bulk continuous polymerization process makes it easy to obtain copolymer (A) and copolymer (B) with high light transmittance. Examples of organic peroxides that can be used include t-butyl peroxybenzoate, t-butyl peroxy-2-ethylhexanoate, 1,1-bis(t-butyl peroxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butyl peroxy)-cyclohexane, 2,2-bis(4,4-di-butyl peroxycyclohexyl)propane, t-butyl peroxyisopropyl monocarbonate, di-t-butyl peroxide, dicumyl peroxide, and ethyl-3,3-di-(t-butyl peroxy)butyrate. The amount of organic peroxide added is preferably 0.001 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the total of two or more monomers.

[0032] As a solvent, at least one selected from, for example, aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane, octane, and isooctane; alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane; and aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene can be used. The amount of solvent added is preferably 5 to 20 parts by mass per 100 parts by mass of the total of two or more monomers. Furthermore, during polymerization, molecular weight modifiers such as 4-methyl-2,4-diphenylpenten-1, t-dodecylmercaptan, and n-dodecylmercaptan may be added. Furthermore, the polymerization temperature is not particularly limited, but is preferably around 80°C to 170°C, and more preferably around 100°C to 160°C.

[0033] In the resin composition of this embodiment, the mixing ratio of copolymer (A) to copolymer (B) is preferably about 20:80 to 80:20 by mass ratio, more preferably about 30:70 to 70:30, and even more preferably about 40:60 to 60:40. By blending copolymer (A) and copolymer (B) in these mass ratios, the light transmittance of the resin composition can be further enhanced. The degree of light transmittance (transparency) of a resin composition can be evaluated by at least one of the total light transmittance and the haze value. Preferably, the resin composition satisfies the following numerical ranges for both the total light transmittance and the haze value. In this specification, the total light transmittance and haze value are values ​​measured in accordance with JIS K 7136:2000 (ISO 14782:1999) for a 2 mm thick sample prepared using a copolymer or resin composition.

[0034] Specifically, the total light transmittance of a 2 mm thick sample made using the resin composition is preferably around 88% or higher, more preferably around 89% or higher, and particularly preferably around 90% or higher. The upper limit of the total light transmittance is usually around 94%. The total light transmittance can be, for example, between 88% and 94%. A resin composition having such a total light transmittance can be evaluated as having excellent light transmittance. Furthermore, the haze value of a 2 mm thick sample prepared using the resin composition is preferably 1% or less, more preferably around 0.6% or less, even more preferably around 0.55% or less, and particularly preferably around 0.5% or less. The lower limit of the haze value is usually around 0.1%. The haze value can be, for example, between 0.1% and 1%. A resin composition having such a haze value can also be evaluated as having excellent light transmittance.

[0035] For dumbbell-shaped samples made using the resin composition, the bending strength measured in accordance with JIS K 7171:2016 (ISO 178:2010) is preferably around 105 MPa or higher, more preferably around 110 MPa or higher, and even more preferably around 115 MPa or higher. The upper limit of the bending strength is usually around 125 MPa. The bending strength can be, for example, between 105 MPa and 125 MPa. A resin composition having such a bending strength can be evaluated as having sufficiently high mechanical strength.

[0036] Furthermore, the temperature at which the resin composition exhibits a 10% mass loss under nitrogen conditions is preferably around 325°C or higher, more preferably between 325°C and 350°C, even more preferably between 330°C and 345°C, and particularly preferably between 330°C and 340°C. In this case, the resin composition can be evaluated as having sufficiently high thermal stability. In this specification, the 10% mass loss temperature is defined as the temperature at which the mass loss of the resin composition becomes 10% relative to the initial mass, as determined by thermogravimetric analysis (TGA).

[0037] The Vicat softening temperature (VST) of the resin composition is preferably between 100°C and 120°C, more preferably between 103°C and 117°C, and even more preferably between 106°C and 114°C. In this case, the resin composition can be evaluated as having sufficiently high heat resistance. In this specification, the Vicat softening temperature is a value measured in accordance with JIS K 7206:2016 (ISO 306:2013).

[0038] The resin composition of this embodiment may optionally contain additives such as antioxidants, lubricants, release agents, plasticizers, pigments, dyes, foaming agents, foaming nucleating agents, inorganic fillers, antistatic agents, and sliding agents. Furthermore, resins such as GP-PS (general-purpose polystyrene), HI-PS (high-impact polystyrene), MBS (methyl methacrylate-butadiene-styrene copolymer) resin, AS (acrylonitrile-styrene copolymer) resin, ABS (acrylonitrile-butadiene-styrene copolymer) resin, PE (polyethylene), PP (polypropylene), and PPO (polyphenylene oxide) may be added to the resin composition.

[0039] The resin compositions described above can be prepared by methods such as uniformly mixing each component in a mixer such as a tumbler or Henschel mixer, and then melt-kneading them in an extruder such as a single-screw extruder or twin-screw extruder. The optical component of this embodiment is composed of the resin composition described above. Such an optical component can have excellent mechanical strength while maintaining high heat resistance and light transmittance. The method for manufacturing the optical component from the resin composition is not particularly limited, but for example, injection molding, press molding, etc., can be used. The optical components are preferably light guide plates, color filters, optical films, lenses, or spectacle lenses. The color filter can be constructed, for example, by dispersing RGB pigments, or by dispersing quantum dots (QDs) for RGB color emission. Furthermore, they may be provided in the following embodiments.

[0040] (1) A resin composition comprising copolymer (A) and copolymer (B) different from copolymer (A), wherein copolymer (A) comprises two or more aromatic vinyl monomer units and (meth)acrylic acid ester monomers, and copolymer (B) comprises one aromatic vinyl monomer unit and (meth)acrylic acid ester monomers, wherein the absolute difference between the content of aromatic vinyl monomer units in copolymer (A) and the content of aromatic vinyl monomer units in copolymer (B) is 25% by mass or less, and the absolute difference between the content of (meth)acrylic acid ester monomers in copolymer (A) and the content of (meth)acrylic acid ester monomers in copolymer (B) is 25% by mass or less.

[0041] (2) A resin composition according to (1) above, wherein the (meth)acrylic acid ester monomer unit of copolymer (A) contains a methyl methacrylate unit, and the aromatic vinyl monomer unit of copolymer (A) contains a styrene unit and an α-methylstyrene unit.

[0042] (3) The resin composition according to (2) above, wherein the content of styrene units in the copolymer (A) is 5% by mass or more and 40% by mass or less, the content of methyl methacrylate units is 40% by mass or more and 80% by mass or less, and the content of α-methylstyrene units is 5% by mass or more and 35% by mass or less.

[0043] (4) A resin composition according to any one of (1) to (3) above, wherein the content of the aromatic vinyl monomer units in the copolymer (B) is 10% by mass or more and 90% by mass or less, and the content of the (meth)acrylic acid ester monomer units is 10% by mass or more and 90% by mass or less.

[0044] (5) A resin composition according to any one of (1) to (4) above, wherein the blending ratio of copolymer (A) to copolymer (B) is 20:80 or more and 80:20 or less by mass ratio.

[0045] (6) A resin composition according to any one of (1) to (5) above, wherein the weight-average molecular weight of the copolymer (B) is 70,000 or more and 300,000 or less.

[0046] (7) A resin composition according to any one of (1) to (6) above, wherein the total light transmittance of a 2 mm thick sample prepared using the resin composition is 88% or more.

[0047] (8) A resin composition according to any one of (1) to (7) above, wherein the bending strength of a dumbbell-shaped sample made using the resin composition, measured in accordance with JIS K 7171:2016, is 105 MPa or more.

[0048] (9) A resin composition according to any one of (1) to (8) above, wherein the haze value of a 2 mm thick sample prepared using the resin composition is 1% or less.

[0049] (10) A resin composition according to any one of (1) to (9) above, wherein the Vicat softening temperature of the resin composition is 100°C or more and 120°C or less.

[0050] (11) A resin composition according to any one of (1) to (10) above, wherein the temperature at which the resin composition loses 10% of its mass in a nitrogen environment is 325°C or higher.

[0051] (12) An optical component comprising the resin composition described in any one of (1) to (11) above.

[0052] (13) An optical component as described in (12) above, wherein the optical component is a light guide plate, a color filter, an optical film, a lens, or a spectacle lens. Of course, this is not always the case.

[0053] Finally, while various embodiments relating to this disclosure have been described, these are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Examples]

[0054] The resin compositions will be described in more detail below using the following examples and comparative examples, but these are not limited to the following examples.

[0055] 1. Preparation of copolymer (A) First, a mixture of 18.5 parts by mass of styrene (hereinafter also referred to as "St"), 56.5 parts by mass of methyl methacrylate (hereinafter also referred to as "MMA"), and 25.1 parts by mass of α-methylstyrene (hereinafter also referred to as "AMS") was further mixed with 0.1 parts by mass of 1,1-bis(t-butylperoxy)-cyclohexane (manufactured by Nippon Oil & Fats Co., Ltd., "Perhexa C") and 0.2 parts by mass of tert-dodecanethiol (manufactured by ARKEMA-France, "tDDM") to prepare a raw material solution.

[0056] Next, this raw material solution was introduced into a fully mixed reactor with a capacity of approximately 20 L, controlled at a rate of 6 kg per hour and a temperature of 125°C. Subsequently, the reaction mixture was continuously withdrawn from the fully mixed reactor. The resulting reaction mixture was added dropwise to hexane and filtered to remove unreacted monomers. The filtrate was vacuum-dried at a controlled temperature of 80°C to obtain copolymer (A).

[0057] 2. Preparation of copolymer (B) ·Copolymer (B-1) MS resin (manufactured by Denka Co., Ltd., "TX-300") was prepared. ·Copolymer (B-2) MS resin (manufactured by Denka Co., Ltd., "TX-800LF") was prepared. ·Copolymer (B-3) MS resin (manufactured by Denka Co., Ltd., "TX-100S") was prepared. ·Copolymer (B-4) MS resin (manufactured by Toyo Styrene Co., Ltd., "MS-750") was prepared.

[0058] 3. Preparation of polymethyl methacrylate (PMMA) PMMA (manufactured by Mitsubishi Chemical Corporation, "VH001") was prepared.

[0059] 4. Preparation of resin composition (Example 1) First, 50 parts by mass of copolymer (A) and 50 parts by mass of copolymer (B-2) were hand-blended. Then, using a single-screw extruder (IKG Corporation, "MS40-32V"), ​​the mixture was melt-kneaded at a cylinder temperature of 180°C to 230°C to form pellets, thereby obtaining a resin composition.

[0060] (Example 2) A resin composition was obtained in the same manner as in Example 1, except that copolymer (B-3) was used instead of copolymer (B-2). (Example 3) A resin composition was obtained in the same manner as in Example 1, except that copolymer (B-4) was used instead of copolymer (B-2).

[0061] (Example 4) A resin composition was obtained in the same manner as in Example 1, except that 80 parts by mass of copolymer (A) and 20 parts by mass of copolymer (B-2) were used. (Example 5) A resin composition was obtained in the same manner as in Example 1, except that 20 parts by mass of copolymer (A) and 80 parts by mass of copolymer (B-2) were used.

[0062] (Comparative Example 1) A resin composition was obtained in the same manner as in Example 1, except that copolymer (B-1) was used instead of copolymer (B-2). (Comparative Example 2) A resin composition was obtained in the same manner as in Example 1, except that PMMA was used instead of copolymer (B-2). (Comparative Example 3) A resin composition was obtained in the same manner as in Example 1, except that the use of copolymer (B-2) was omitted and only copolymer (A) (100 parts by mass) was used.

[0063] (Comparative Example 4) A resin composition was obtained in the same manner as in Comparative Example 2, except that the use of copolymer (A) was omitted and only PMMA (100 parts by mass) was used. (Comparative Example 5) A resin composition was obtained in the same manner as in Example 1, except that copolymer (A) was omitted and only copolymer (B-2) (100 parts by mass) was used.

[0064] 5. Measurement 5-1. Measurement of monomer content Copolymer (A) and copolymers (B-1) to (B-4) were each dissolved in deuterated chloroform to prepare samples. 13 The area ratio of spectral peaks attributable to each monomer unit was calculated using 1C-NMR. 5-2. Measurement of weight-average molecular weight The weight-average molecular weights of copolymer (A), copolymers (B-1) to (B-4), and PMMA were measured by GPC and determined on a polystyrene basis.

[0065] 5-3. Measurement of total light transmittance and haze value Using copolymer (A), copolymers (B-1) to (B-4), PMMA, the resin compositions of Examples 1 to 5, and the resin compositions of Comparative Examples 1 to 5, samples measuring 30 mm × 55 mm and 2 mm thick were prepared using an injection molding machine (Nippon Steel Corporation, "J140AD-180H") under conditions of a molding temperature of 230°C and a mold temperature of 60°C. The total light transmittance and haze value of these samples were measured in accordance with JIS K 7136:2000. Measurement of the 5-4.10% mass loss temperature For each of the resin compositions of Examples 1 to 5 and Comparative Examples 1 to 5, a thermogravimetric analyzer (Hitachi High-Tech Science Corporation, "TG / DTA7200") was used to heat the composition to 500°C at a rate of 20°C / min under nitrogen conditions, and the temperature at which the mass decreased by 10% was measured.

[0066] 5-5. Measurement of Bending Strength Using the resin compositions of Examples 1-5 and Comparative Examples 1-5, dumbbell-shaped samples were prepared using an injection molding machine (Nippon Steel Corporation, "J140AD-180H"). The bending strength of these samples was measured using a bending test machine (Toyo Seiki Co., Ltd., "Bendgraph II") under test conditions of 2 mm / min, in accordance with JIS K 7171:2016. 5-6. Measurement of Vicat softening temperature For each of the resin compositions of Examples 1 to 5 and Comparative Examples 1 to 5, the Vicat softening temperature was measured according to JIS K 7206:2016 using the 50 method (load 50N, heating rate 50°C / hour).

[0067] 5-7. Measurement of Density The density of each of the resin compositions of Examples 1 to 5 and Comparative Examples 1 to 5 was measured using a density gradient tube in accordance with JIS K 7112-1:2023. These results are shown in Tables 1 to 3 below.

[0068] [Table 1]

[0069] [Table 2]

[0070] [Table 3]

[0071] As shown in Table 2, the resin compositions of each example exhibited excellent light transmittance (high total light transmittance and low haze value), and maintained heat resistance, as indicated by the Vicat softening temperature. Furthermore, the resin compositions of each example also had high flexural strength (mechanical strength). In contrast, as shown in Table 3, the resin compositions of Comparative Examples 1 and 2 had sufficient heat resistance and flexural strength, but their light transmittance was poor due to poor compatibility between copolymers or between copolymers and PMMA, which prevented uniform mixing. Furthermore, the resin composition of Comparative Example 3 had poor heat resistance.

[0072] Furthermore, it was confirmed that the density (specific gravity) of the resin composition decreases when copolymer (A) and / or copolymer (B) contain St units. Therefore, if molded articles are manufactured using such resin compositions, the weight of the molded articles can be reduced. Furthermore, if copolymer (A) is produced in which the content of St units is changed in the range of 5% to 40% by mass, the content of MMA units in the range of 40% to 80% by mass, and the content of AMS units in the range of 5% to 35% by mass, and a resin composition is prepared in the same manner as above, the same measurement results as in the above example can be obtained.

[0073] Furthermore, when polymer (B) is produced in which the content of styrene monomer units is changed in the range of 10% by mass or more and 90% by mass or less, and the content of (meth)acrylic acid ester monomer units is changed in the range of 10% by mass or more and 90% by mass or less, and a resin composition is prepared in the same manner as above, the same measurement results as in the above examples can be obtained. Furthermore, the same measurement results as in the above examples can be obtained when the types of styrene monomer units and (meth)acrylic acid ester monomer units are changed, or when the mixing ratio of copolymer (A) and copolymer (B) is changed.

Claims

1. A resin composition, It contains copolymer (A) and copolymer (B) which is different from copolymer (A), The copolymer (A) comprises two or more aromatic vinyl monomer units and a (meth)acrylic acid ester monomer, and the copolymer (B) comprises one aromatic vinyl monomer unit and a (meth)acrylic acid ester monomer. A resin composition in which the absolute difference between the content of the aromatic vinyl monomer units in copolymer (A) and the content of the aromatic vinyl monomer units in copolymer (B) is 25% by mass or less, and the absolute difference between the content of the (meth)acrylic acid ester monomer in copolymer (A) and the content of the (meth)acrylic acid ester monomer in copolymer (B) is 25% by mass or less.

2. In the resin composition according to claim 1, A resin composition wherein the (meth)acrylic acid ester monomer unit of the copolymer (A) contains a methyl methacrylate unit, and the aromatic vinyl monomer unit of the copolymer (A) contains a styrene unit and an α-methylstyrene unit.

3. In the resin composition according to claim 2, A resin composition wherein the copolymer (A) contains 5% by mass or more and 40% by mass or less of styrene units, contains 40% by mass or more and 80% by mass or less of methyl methacrylate units, and contains 5% by mass or more and 35% by mass or less of α-methylstyrene units.

4. In the resin composition according to claim 1, A resin composition wherein the content of the aromatic vinyl monomer units in the copolymer (B) is 10% by mass or more and 90% by mass or less, and the content of the (meth)acrylic acid ester monomer units is 10% by mass or more and 90% by mass or less.

5. In the resin composition according to claim 1, A resin composition in which the mixing ratio of copolymer (A) and copolymer (B) is 20:80 or more and 80:20 or less by mass ratio.

6. In the resin composition according to claim 1, A resin composition wherein the weight-average molecular weight of the copolymer (B) is 70,000 or more and 300,000 or less.

7. In the resin composition according to claim 1, The resin composition wherein the total light transmittance of a 2 mm thick sample prepared using the resin composition is 88% or more.

8. In the resin composition according to claim 1, A resin composition wherein a dumbbell-shaped sample prepared using the aforementioned resin composition exhibits a bending strength of 105 MPa or more, as measured in accordance with JIS K 7171:2016.

9. In the resin composition according to claim 1, A resin composition wherein the haze value of a 2 mm thick sample prepared using the resin composition is 1% or less.

10. In the resin composition according to claim 1, The resin composition wherein the Vicat softening temperature of the resin composition is 100°C or higher and 120°C or lower.

11. In the resin composition according to claim 1, A resin composition wherein the temperature at which the resin composition loses 10% of its mass under a nitrogen environment is 325°C or higher.

12. It is an optical component, An optical component comprising the resin composition described in any one of claims 1 to 11.

13. In the optical component according to claim 12, The optical component is an optical component that is a light guide plate, a color filter, an optical film, a lens, or a spectacle lens.

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