Styrene-based copolymer

Abstract

To provide a styrene-based copolymer that achieves stabilization against thermal oxidative degradation.SOLUTION: A styrene-based copolymer comprises a copolymer composition including (A) 69 to 99.99 wt.% of a styrene-based monomer, (B) 0.01 to 1 wt.% of a phenothiazine derivative compound monomer represented by general formula (where R1 denotes a monovalent aliphatic hydrocarbon group having 1-10 carbon atoms and R2 denotes a hydrogen atom or a methyl group), and (C) 0 to 30 wt.% of at least one monomer selected from alkyl (meth)acrylate monomers, aralkyl (meth)acrylate monomers, α,β-ethylenically unsaturated carboxylic acid monomers, and nitrile group-containing polymerizable unsaturated monomers.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to styrenic copolymers, and more particularly to styrenic copolymers stabilized against thermo-oxidative degradation. [Background technology]

[0002] Polystyrene resins are excellent in transparency, gloss, and weather resistance, and are lightweight and inexpensive, and are therefore used in a wide range of applications including the automotive, home appliance, and daily necessities fields.

[0003] Antioxidants are used to prevent oxidative degradation of styrene resins during their production and processing, and during the use of molded products thereof. Commonly used antioxidants include phenolic antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants.

[0004] In the process for producing styrene-based resins, after polymerization of raw material monomers, an antioxidant or the like is added to the polymerization solution to prevent deterioration of the polymerized product due to the heat history in post-treatment processes such as unreacted monomer recovery, desolvation, drying, and pelletization.

[0005] Furthermore, to prevent oxidative deterioration of styrene resins due to oxygen or ozone during molding and processing and during use, an antioxidant or the like is added as needed.

[0006] However, there are concerns about styrene-based resins, such as poor appearance due to migration of the antioxidant to the surface, volatilization of the antioxidant due to exposure to high temperatures, and extraction of the antioxidant by water, oils, organic solvents, etc. These factors can cause the antioxidant in the molded product to be lost over time, reducing its original antioxidant function. As a result, the molded product's lifespan can be shortened due to problems such as reduced mechanical properties and poor appearance due to oxidative degradation.

[0007] To solve these problems, several methods have been disclosed in which an antioxidant having a polymerizable unsaturated group is copolymerized with a polymerizable unsaturated monomer and the antioxidant component is chemically bonded to a polymer chain (Non-Patent Document 1). However, conventional diphenylamine derivative compounds and hindered phenol derivative compounds having a polymerizable unsaturated group contain active hydrogen that inactivates peroxy radicals, which can conversely inhibit the initiation reaction of radical polymerization or anionic polymerization in the polymerization process. Furthermore, the disclosed antioxidants having a methacryloyl group or acryloyl group as the polymerizable unsaturated group may have difficulty in anionic copolymerization with aromatic vinyl monomers such as styrene.

[0008] For example, radical polymerization of 2-ethenyl-10H-phenothiazine has been disclosed (Non-Patent Document 2). However, a high molecular weight homopolymer was not obtained, which is presumed to be due to the radical polymerization inhibitory effect of the hydrogen atom at the 10-position of the phenothiazine moiety. [Prior art documents] [Non-patent literature]

[0009] [Non-Patent Document 1] Rubber Chem.Technol., Vol. 46, p. 106 (1973) [Non-patent document 2] Russian Journal of Applied Chemistry, Vol. 76, p. 1327 (2003) [Non-patent document 3] Organic Letters, Vol. 23, p. 4564 (2021) [Non-patent document 4] Energy Environ.Sci., Vol. 10, pp. 2334-2341 (2017) Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made in view of the above-mentioned problems, and has as its object to provide a styrene copolymer that is stabilized against thermo-oxidative degradation. [Means for solving the problem]

[0011] The object of the present invention is to provide a polymerizable composition comprising (A) 69 to 99.99% by weight of a styrene-based monomer, (B) a polymerizable composition having the general formula TIFF2025121817000001.tif25129 (where R 1 is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and R 2 is a hydrogen atom or a methyl group) and (C) 0 to 30% by weight of a monomer consisting of at least one of an alkyl (meth)acrylate monomer, an aralkyl (meth)acrylate monomer, an α,β-ethylenically unsaturated carboxylic acid monomer, and a nitrile group-containing polymerizable unsaturated monomer. [Effects of the Invention]

[0012] The styrene copolymer of the present invention is stabilized against thermal oxidative degradation by itself, and therefore, it is possible to prevent oxidative degradation during the copolymer production process without adding an antioxidant. Specifically, it has the excellent effect of suppressing yellowing of the copolymer and changes in melt flow rate during degassing, drying, and extrusion processes after polymerization.

[0013] Furthermore, when a part obtained by molding the styrene-based copolymer of the present invention is used, the poor appearance caused by migration of the antioxidant to the surface is improved, and the volatilization of the antioxidant due to heat or the extraction of the antioxidant by a liquid medium such as water, oils and fats, or an organic solvent is suppressed. This prevents the resin from changing in hue or decreasing in mechanical properties under various usage environments, thereby enabling the molded part to be used safely and with a longer life. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention relates to a styrene-based copolymer, which comprises (A) a styrene-based monomer and (B) a copolymer represented by the general formula TIFF2025121817000002.tif25129 (where R 1 is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and R 2 is a hydrogen atom or a methyl group).

[0015] (B) In the phenothiazine derivative compound [I], R 1 Specific examples of the alkyl group include secondary hydrocarbon groups such as a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, an isopropyl group, a 2-butyl group, a 2-pentyl group, a 3-pentyl group, a 2-hexyl group, a 3-hexyl group, a 2-heptyl group, a 3-heptyl group, a 4-heptyl group, a 2-octyl group, a 3-octyl group, and a 4-octyl group; tertiary hydrocarbon groups such as a tertiary butyl group, a 1,1-dimethyl-1-propyl group, a 1,1-dimethyl-1-butyl group, a 1,1-dimethyl-1-pentyl group, a 1,1-dimethyl-1-hexyl group, a 3-methyl-3-pentyl group, a 3-ethyl-3-pentyl group, and a 3-methyl-3-hexyl group; alicyclic hydrocarbon groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a 1-methyl-1-cyclopentyl group, and a 1-methyl-1-cyclohexyl group; Examples include a 1-adamantyl group.

[0016] Specific examples of the phenothiazine derivative compound [I] include 2-ethenyl-10-methyl-10H-phenothiazine, 2-(1-methylethenyl)-10-methyl-10H-phenothiazine, 3-ethenyl-10-methyl-10H-phenothiazine, and 3-(1-methylethenyl)-10-methyl-10H-phenothiazine. There are no particular limitations on the method for producing such phenothiazine derivative compound [I], and it can be produced using inexpensive diphenylamine or 10H-phenothiazine as a starting material. For example, Non-Patent Documents 3 and 4 describe methods for producing 2-(1-methylethenyl)-10-methyl-10H-phenothiazine and 3-ethenyl-10-methyl-10H-phenothiazine, respectively.

[0017] The phenothiazine derivative compound [I] is essentially different from, for example, 2-ethenyl-10H-phenothiazine described in Non-Patent Document 2 in that the hydrogen atom at the 10-position is substituted with an aliphatic hydrocarbon group. This prevents hydrogen abstraction by radical species in radical polymerization, thereby suppressing the radical polymerization inhibitory effect specific to phenothiazine.

[0018] In anionic polymerization, for the same reason, hydrogen abstraction reactions by basic compounds such as alkyllithium compounds are substantially avoided, and therefore, the activity of the anionic polymerization initiating species can be prevented from decreasing.

[0019] Furthermore, in cationic polymerization and coordination polymerization, the activity of the cationic polymerization catalyst and coordination polymerization catalyst is prevented from decreasing for the same reason.

[0020] For these reasons, the phenothiazine derivative compound [I] can be radically copolymerized, anionicly copolymerized, cationicly copolymerized and coordinately copolymerized with various polymerizable unsaturated monomers including styrene-based monomers.

[0021] (A) Examples of styrene-based monomers include styrene, α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-ethylstyrene, and 4-tert-butylstyrene, and styrene is preferred from the viewpoint of practicality.

[0022] In addition, (C) alkyl (meth)acrylate monomers, aralkyl (meth)acrylate monomers, α,β-ethylenically unsaturated carboxylic acid monomers, or nitrile group-containing polymerizable unsaturated monomers can be copolymerized alone or in combination of two or more types in a proportion of 30% by weight or less, for example, 1 to 30% by weight, based on the total weight of the copolymer. Here, (meth)acrylate refers to acrylate or methacrylate.

[0023] Examples of the alkyl (meth)acrylate monomer that can be used include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, cyclohexyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, and n-octadecyl (meth)acrylate.

[0024] Examples of the aralkyl (meth)acrylate monomer include benzyl (meth)acrylate.

[0025] Examples of the α,β-ethylenically unsaturated carboxylic acid monomer include monobasic α,β-ethylenically unsaturated carboxylic acid monomers and dibasic α,β-ethylenically unsaturated carboxylic acid monomers, and specific examples thereof include acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid.

[0026] The nitrile group-containing polymerizable unsaturated monomer may be acrylonitrile.

[0027] In copolymerizing (A) a styrene-based monomer, (B) a phenothiazine derivative compound [I], and (C) other polymerizable unsaturated monomers, the compound [I] is used in an amount of about 0.01 to 1.0% by weight, preferably about 0.01 to 0.2% by weight, per 100 parts by weight of the monomer mixture. If the compound [I] is used in an amount less than this, a sufficient antioxidant effect cannot be expected, while if the compound is used in an amount greater than this, an improvement in the antioxidant effect cannot be expected, and this is uneconomical.

[0028] As a method for producing a styrene copolymer, a radical polymerization method, an anionic polymerization method, a cationic polymerization method, a coordination polymerization method, or the like can be used from the viewpoint of the active species in the polymerization reaction, and a solution polymerization method, a bulk polymerization method, an emulsion polymerization method, a suspension polymerization method, a gas phase polymerization method, or the like can be used from the viewpoint of the phase state of the polymerization reaction, and various polymerization methods are appropriately used depending on the type and application of the styrene copolymer.

[0029] In bulk polymerization by radical polymerization, an organic peroxide is used as a polymerization initiator at a polymerization temperature of 80 to 160°C. Examples of organic peroxides include peroxyketals such as 2,2-bis(tert-butylperoxy)butane, 2,2-bis(tert-butylperoxy)octane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, and n-butyl-4,4-bis(tert-butylperoxy)valerate; dialkyl peroxides such as di-tert-butyl peroxide, tert-butylcumyl peroxide, dicumyl peroxide, and α,α'-bis(tert-butylperoxyisopropyl)benzene; acetyl peroxide; and isobutyryl peroxide. peroxydicarbonates such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and di-n-propyl peroxydicarbonate; peroxyesters such as tert-butyl peroxyacetate and tert-butyl peroxyisobutyrate; ketone peroxides such as acetylacetone peroxide and methyl ethyl ketone peroxide; and hydroperoxides such as tert-butyl hydroperoxide, cumene hydroperoxide, and diisopropylbenzene hydroperoxide.

[0030] Further, diazo compounds such as azobisisobutyronitrile and azobisisovaleronitrile can also be used.

[0031] Furthermore, if necessary, the polymerization can be carried out in the presence of a chain transfer agent such as α-methylstyrene dimer, n-dodecyl mercaptan, or tertiary dodecyl mercaptan.

[0032] In solution polymerization using the radical polymerization method, the same polymerization initiator as in bulk polymerization is used. Toluene, ethylbenzene, xylene, etc. are used as polymerization solvents. The polymerization temperature is in the range of 80 to 160°C.

[0033] In solution polymerization using an anionic polymerization method, an alkyllithium compound is used as a polymerization initiator. Specific examples include n-butyllithium and sec-butyllithium. Toluene, cyclohexane, benzene, etc. are used as the polymerization solvent. The polymerization temperature is in the range of -80 to 100°C.

[0034] The melt flow rate of the styrene copolymer of the present invention is not particularly limited, but is preferably from 1 to 20. The melt flow rate is a value measured at 200° C. under a load of 5 kg.

[0035] Furthermore, the weight average molecular weight (Mw) of the styrene resin is not particularly limited, but when produced by radical polymerization, it is preferably 100,000 to 500,000, and the ratio (Mz / Mw) of the Z average molecular weight (Mz) to the weight average molecular weight (Mw) is 2.0 to 5.5.

[0036] When produced by anionic polymerization, the weight average molecular weight (Mw) is 100,000 to 500,000, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 1.0 to 3.0. [Example]

[0037] The present invention will now be described in detail with reference to examples, although the present invention, including its effects, is not limited to these examples.

[0038] Reference example 1 -Production of phenothiazine derivative compound [IA]- TIFF2025121817000003.tif25170

[0039] [1st process] [PTZ] → (a): A 5-L five-neck flask equipped with a stirrer, thermometer, dropping funnel, nitrogen gas inlet, and outlet tube was charged with 2.0 L of thoroughly dehydrated N,N-dimethylformamide. The system was cooled to below 10°C under a nitrogen atmosphere. 103.4 g (2.59 mol) of sodium hydride (60% purity) was added and stirred for 10 minutes. After this, 401 g (2.01 mol) of phenothiazine (PTZ) was added in several portions and reacted for 30 minutes while maintaining the system temperature below 10°C. 312.3 g (2.20 mol) of iodomethane was added dropwise while maintaining the system temperature below 10°C, and the reaction was continued for an additional hour. After the reaction was complete, the reaction mixture was added to 4 L of 10% aqueous sodium chloride solution. The colorless solid precipitated was filtered and then washed with 4 L of distilled water. The resulting solid was dissolved in 2.5 L of ethyl acetate at approximately 50°C, and the lower layer (aqueous layer) was separated. The upper layer (organic layer) was dried over anhydrous magnesium sulfate, and then insoluble matter was filtered off. Volatile components were removed from the filtrate by distillation under reduced pressure to obtain 451.4 g of a crude product (crude yield 105%). This was washed (defatted) with 0.7 L of isooctane to obtain 421.2 g of 10-methyl-10H-phenothiazine (a) as a slightly grayish crystalline solid (yield 98.2%). TIFF2025121817000004.tif25129 1 H NMR (400MHz, Acetone-d6, δ ppm): 3.39 (s, 3H, NC H 3) 6.91-6.98 (m, 4H, Ar) 7.14 (dd, J=7.6Hz, J=1.6Hz, 2H, Ar) 7.21 (td, J=7.6Hz, J=1.6Hz, 2H, Ar)

[0040] [Second step] (a)→(b): A 3 L five-neck flask equipped with a stirrer, dropping funnel, thermometer, gas inlet, gas outlet, and reflux condenser was charged with 0.7 L of thoroughly dehydrated N,N-dimethylformamide. Under a nitrogen atmosphere, 509 g (3.32 mol) of phosphoryl chloride was added dropwise while maintaining the internal temperature of the system below 10°C, and the reaction was continued for an additional 30 minutes. Next, 291.2 g (1.37 mol) of 10-methyl-10H-phenothiazine (a) obtained in the first step above was added, and the reaction was continued at 60°C for 17 hours. After the reaction was completed, the contents were poured into 2.3 kg of 50% aqueous sodium acetate solution cooled in an ice-water bath, and 194 g of sodium hydroxide was added to adjust the pH to 6 or higher. The resulting solution was allowed to stand for 2 hours while cooled in an ice-water bath. The precipitated solid was filtered off and washed with 3 L of distilled water to dissolve the inorganic electrolytes. The remaining brown solid was dissolved in 1.5 L of warm ethyl acetate at approximately 50°C. The lower layer (aqueous layer) was separated, and the organic layer was dried over anhydrous magnesium sulfate. After filtering off the insoluble matter, the volatile components were removed from the filtrate by distillation under reduced pressure, yielding 329.0 g of crude product (crude yield 99.9%) as a reddish-brown oil. The crude product was dissolved in approximately 1 L of ethyl acetate and passed through a silica gel (carrier: Wakogel C300) column to remove low-Rf components. The volatile components were removed from the eluate by distillation under reduced pressure, yielding 321.6 g of a yellow solid (yield 97.6%). Further recrystallization using 320 mL of ethyl acetate yielded 308.2 g of 10-methyl-10H-phenothiazine-3-carbaldehyde (b) as yellow crystals (yield 93.6%). TIFF2025121817000005.tif26128 1 H NMR (400MHz, Acetone d6, δ ppm): 3.49 (s, 3H, NC H 3) 7.00-7.06 (m, 2H, Ar) 7.10 (d, J=8.4Hz, 1H, Ar) 7.15-7.19 (m, 1H, Ar) 7.22-7.28 (m, 1H, Ar) 7.61 (d, J=1.6Hz, 1H, Ar) 7.75 (dd, J=8.4Hz, J=1.6Hz, 1H, Ar) 9.85 (s, 1H, -C H O)

[0041] [3rd step] (b) → [IA]: A 5-L five-neck flask equipped with a stirrer, magnetic stirrer, thermometer, gas inlet, and outlet tubes was charged with 2.3 L of tetrahydrofuran. The reaction vessel was cooled to below 10°C while purging with nitrogen. 175.0 g (1.56 mol) of potassium tert-butoxide was added, followed by 557.3 g (1.56 mol) of methyltriphenylphosphonium bromide, and the reaction was carried out for 30 minutes. 313.7 g (1.30 mol) of compound (b) was added and the reaction was carried out at -10 to 40°C for 1 hour to obtain a reaction mixture. The reaction mixture was then added to 1.7 L of 10% aqueous sodium chloride solution to terminate the reaction. The organic layer was recovered, while the aqueous layer was extracted with ethyl acetate and mixed with the organic layer. 0.35 g of p-methoxyphenol was added to the mixture, which was then dried over anhydrous magnesium sulfate. After filtering off insoluble materials, the filtrate was evaporated under reduced pressure to obtain 718.4 g of a pale yellow solid. This was crushed in a mortar to obtain a powder. The powdery pale yellow solid was dissolved in 2.1 L of ethanol, and a small amount of insoluble matter was filtered off. The filtrate was then left overnight at 5°C or below to crystallize [IA]. The precipitated yellow crystals weighed 286.3 g (yield 92.0%). The same procedure was repeated using 3.3 L of ethanol with 286.3 g of the precipitated yellow crystals to obtain 259.2 g of [IA] as pale yellow crystals (yield 83.3%). TIFF2025121817000006.tif25129 Melting point: 102°C 1 H NMR (400MHz, CDCl3, δ ppm): 3.37 (s, 3H, NC H 3) 5.14 (d, J=10.8Hz, 1H, C H 2=CH-PTZ (trans to the phenothiazine group) 5.61 (d, J=17.6Hz, 1H, C H 2=CH-PTZ (cis to the phenothiazine group) 6.59 (dd, J=10.8Hz, 17.6Hz, 1H, CH2=C H -PTZ) 6.75 (d, J=8.4Hz, 1H, Ar) 6.81 (d, J=9.2Hz, 1H, Ar) 6.92 (td, J=7.6Hz, 1.2Hz, 1H, Ar) 7.11-7.23 (m, 4H, Ar)

[0042] Reference example 2 -Production of phenothiazine derivative compound [IB]- TIFF2025121817000007.tif40155

[0043] [1st process] (A-PTZ) → (c): A 1 L four-neck flask equipped with a magnetic stirrer, thermometer, nitrogen gas inlet, outlet, and reflux condenser was charged with 16.4 g (68.0 mmol) of 2-acetylphenothiazine (A-PTZ), 400 mL of toluene, 36 g of ethylene glycol, and 0.70 g of p-toluenesulfonic acid monohydrate, and refluxed under a nitrogen atmosphere for 10 hours. The reaction mixture was added to 600 mL of 10% aqueous sodium chloride solution. This was extracted with ethyl acetate, and the organic layer was dried over anhydrous magnesium sulfate. Insoluble matter was then filtered off. Volatile components were removed from the filtrate by distillation under reduced pressure, yielding 16.3 g (84% crude yield) of compound (c) as a brown solid. TIFF2025121817000008.tif25128

[0044] [Second step] (c)→(d): A 500 mL four-neck flask equipped with a magnetic stirrer, thermometer, dropping funnel, nitrogen gas inlet, and outlet tube was charged with 200 mL of thoroughly dehydrated N,N-dimethylformamide. The system was cooled to below 10°C under a nitrogen atmosphere. 4.6 g (115 mmol) of sodium hydride (60% purity) was added and stirred for 10 minutes. After stirring, 16.3 g (57.1 mmol) of compound (c) was added while maintaining the system temperature below 10°C, and the reaction was continued for 30 minutes. While maintaining the system temperature below 10°C, 12.2 g (86 mmol) of iodomethane was added dropwise, and the reaction was continued for an additional hour. After the reaction was complete, the reaction mixture was added to 600 mL of 10% aqueous sodium chloride solution. After extraction with ethyl acetate, the upper layer (organic layer) was dried over anhydrous magnesium sulfate, and insoluble matter was then filtered off. Volatile components were distilled off from the filtrate under reduced pressure to obtain 17.2 g of compound (d) as a yellow solid (crude yield from compound (c) 101%). TIFF2025121817000009.tif25128

[0045] [3rd step] (d)→(e): 17.2 g of compound (d), 40 ml of distilled water, and 160 ml of acetic acid were placed in a 500 ml four-neck flask equipped with a magnetic stirrer and thermometer, and the reaction was carried out at 90°C for 2 hours. The reaction mixture was added to 600 ml of 10% aqueous sodium chloride solution. This was extracted with ethyl acetate, and the organic layer was dried over anhydrous magnesium sulfate. Insoluble matter was then filtered off. Volatile components were removed from the filtrate under reduced pressure, yielding 15.4 g of compound (e) as a brown liquid (crude yield from compound (c) 106%). TIFF2025121817000010.tif25128

[0046] [4th step] (e) → [IB]: A 500 mL four-neck flask equipped with a magnetic stirrer, thermometer, gas inlet, and outlet tubes was charged with 150 mL of tetrahydrofuran. The reaction vessel was cooled to below 10°C while purging with nitrogen. 8.3 g (74.0 mmol) of potassium tert-butoxide was added, followed by 25.6 g (74.2 mmol) of methyltriphenylphosphonium bromide, and the reaction was allowed to proceed for 30 minutes. 15.4 g (approximately 57.1 mmol) of compound (e) was then added and the reaction was allowed to proceed for 1 hour at temperatures ranging from -10 to 40°C. The reaction mixture was then quenched by adding 700 mL of 10% aqueous sodium chloride solution. The organic layer was then recovered, while the aqueous layer was extracted with ethyl acetate and mixed with the organic layer. 0.02 g of p-methoxyphenol was added to the resulting mixture, which was then dried over anhydrous magnesium sulfate and filtered to remove any insoluble material. Volatile components were removed from the filtrate under reduced pressure, yielding 32.2 g of a brown liquid. This was subjected twice to column chromatography (stationary phase: Wakogel C300, φ60 mm, L=80 mm) using dichloromethane as an eluent to remove triphenylphosphine oxide. Volatile components were then distilled off from the eluate under reduced pressure to obtain 13.0 g of compound [IB] as a pale yellow solid (yield from compound (c) 90%). TIFF2025121817000011.tif25129 1 H NMR (400MHz, acetone-d6, δ ppm): 2.13 (s, 3H, CH2=C(C H 3)-PTZ) 3.42 (s, 3H, NC H 3) 5.08 (m, 1H, C H 2=C(CH3)-PTZ (trans to the phenothiazine group) 5.41 (m, 1H, C H 2=C(CH3)-PTZ (cis to the phenothiazine group) 6.91-7.23 (m, 7H, Ar)

[0047] Example 1 A 200 ml flask was charged with 30 g of styrene, 30 mg of compound [IA], and 90 mg of azobisisobutyronitrile. After three cycles of freeze-degassing, the polymerization reaction was carried out at 80°C for 24 hours. The contents were slightly yellow at the beginning of the polymerization, but became a colorless solid at the end of the polymerization. This was dissolved in toluene and removed from the reaction vessel. The conversion rate was 96% based on the evaporation-to-dryness method. The toluene solution of the copolymer was heated on a hot plate at 150°C for 1 hour to remove volatile components. Further drying under reduced pressure at 100°C for 1.5 hours yielded a resinous styrene-compound [IA] copolymer.

[0048] A portion of the toluene solution of the copolymer removed from the reaction vessel was added to methanol to precipitate the copolymer, which was then dried under reduced pressure at 60°C for 3 hours. 1 H-NMR and GPC analysis.

[0049] The mole fraction composition of the copolymer is l From the H-NMR (400 MHz, CDCl3, δ ppm) analysis, the content of the compound [IA] was calculated from the following formula, and the content of styrene was found to be 0.040 mol % and 99.960 mol %. α: Integrated value of the signal between 3.1 and 3.4 ppm β: Integrated value of the signal between 5.9 and 7.7 ppm Compound [IA] (mol%) = 500 × α / (5α + 3β) Styrene (mol%) = 100 - Compound [IA]

[0050] The weight fraction composition was calculated from the following formula, and was found to be 0.09% by weight of compound [IA] and 99.91% by weight of styrene. Compound [IA] (wt%) = (Compound [IA] (mol%) × 239.34 × 100) / [Compound [IA] (mol%) × 239.34 + Styrene (mol%) × 104.1] Styrene (wt%) = 100 - Compound [IA] (wt%)

[0051] The weight-average molecular weight (Mw) and Z-average molecular weight (Mz) were measured by gel permeation chromatography (GPC) under the following conditions: Mw: 3.56 × 10 5 , Mz is 1.84 x 10 6 and Mz / Mw was 5.2. Equipment: Shimadzu HPLC system 20A Column: Shodex GPC KF-807L x 4 Detector: RI Measurement temperature: 40℃ Sample concentration: 0.2% THF solution Carrier (THF) flow rate: 1.0 ml / min

[0052] Example 2 In Example 1, the amount of compound [IA] was changed to 15 mg, and a resinous styrene-compound [IA] copolymer was obtained. The polymerization rate was 95%, and the weight fraction composition was 0.05% by weight of compound [IA] and 99.95% by weight of styrene. The Mw was 2.55 × 10 5 , Mz is 1.06 x 10 6 and Mz / Mw was 4.2.

[0053] Example 3 In Example 1, the same amount (30 mg) of compound [IB] was used instead of compound [IA] to obtain a resinous styrene-compound [IB] copolymer. The conversion was 96% and the Mw was 3.33 × 10 5 , Mz is 1.64 x 10 6 and Mz / Mw was 4.9.

[0054] In addition, lAttempts to determine the amount of compound [IB] in the resulting copolymer using H-NMR (400 MHz, CDCl3, δ ppm) from the following equation were impossible because no signal was detected at 3.1-3.4 ppm. This is presumably due to the loss of methyl groups on the nitrogen atoms due to thermal history. However, judging from the weight fraction composition of the amounts of styrene and compound [IB] added, the weight fraction of compound [IB] in the copolymer is presumed to be in the range of 0.05-0.10 wt%. α: Integrated value of the signal between 3.1 and 3.4 ppm β: Integrated value of the signal between 5.9 and 7.7 ppm Compound [IB] (mol%) = 500 × α / (5α + 3β) Styrene (mol%) = 100 - Compound [IB]

[0055] Comparative Example 1 In Example 1, the compound [IA] was not used, and a resinous styrene homopolymer was obtained. The polymerization rate was 96%, and the Mw was 3.36×10 5 , Mz is 1.67 x 10 6 and Mz / Mw was 5.0.

[0056] Comparative Example 2 To the toluene solution of the styrene homopolymer obtained in Comparative Example 1, 0.1 parts by weight of 2,6-di-tert-butyl-4-methylphenol (BHT: a product of Tokyo Chemical Industry Co., Ltd.), a phenolic antioxidant, was added per 100 parts by weight of solid content, and then the volatile components were removed and the mixture was dried under reduced pressure under the same conditions as in Example 1 to obtain a styrene resin composition.

[0057] Comparative Example 3 In Comparative Example 2, the same amount (0.1 parts by weight) of Irganox 1010, a product of BASF, was used as the phenolic antioxidant in place of 2,6-di-tert-butyl-4-methylphenol to obtain a styrene resin composition.

[0058] Comparative Example 4 To the toluene solution of the styrene homopolymer obtained in Comparative Example 1, 0.1 parts by weight of compound [IA] was added per 100 parts by weight of solid content, and then the volatile components were removed and the mixture was dried under reduced pressure under the same conditions as in Example 1 to obtain a styrene resin composition.

[0059] Comparative Example 5 To the toluene solution of the styrene homopolymer obtained in Comparative Example 1, 0.1 parts by weight of compound (a) of Reference Example 1 was added per 100 parts by weight of solid content, and then volatile components were removed and the mixture was dried under reduced pressure under the same conditions as in Example 1 to obtain a styrene resin composition.

[0060] Example 4 In Example 1, the amount of styrene was changed to 28.5 g, and 1.5 g of methyl methacrylate was further used to obtain a resinous styrene-methyl methacrylate-compound [IA] copolymer. The polymerization rate was 96%, the weight fraction composition was 95.15 wt% styrene and 4.85 wt% methyl methacrylate, and the Mw was 3.10 × 10 5 , Mz is 1.40 x 10 6 The Mz / Mw ratio was 4.5. Note that the signal at 3.1-3.4 ppm derived from compound [IA] overlapped with the signal derived from methyl methacrylate, so the weight fraction of compound [IA] could not be determined.

[0061] Comparative Example 6 In Example 4, compound [IA] was not used, and a resinous styrene-methyl methacrylate copolymer was obtained. The polymerization rate was 93%, the weight fraction composition was 94.83% by weight of styrene and 5.17% by weight of methyl methacrylate, and the Mw was 3.20 × 10 5 , Mz is 1.47 x 10 6 and Mz / Mw was 4.6.

[0062] Example 5 In Example 4, the amount of styrene was changed to 27.0 g and the amount of methyl methacrylate to 3.0 g, respectively, to obtain a resinous styrene-methyl methacrylate-compound [IA] copolymer. The polymerization rate was 94%, the weight fraction composition was 90.63 wt% styrene and 9.37 wt% methyl methacrylate, and the Mw was 2.57 × 10 5 , Mz is 9.48 x 10 5 and Mz / Mw was 3.7. For the same reason as in Example 4, it was not possible to determine the weight fraction of compound [IA].

[0063] Comparative Example 7 In Example 5, compound [IA] was not used, and a resinous styrene-methyl methacrylate copolymer was obtained. The polymerization rate was 95%, the weight fraction composition was 90.63% by weight of styrene and 9.37% by weight of methyl methacrylate, and the Mw was 2.56 × 10 5 , Mz is 9.96 x 10 5 and Mz / Mw was 3.9.

[0064] Example 6 In Example 4, the amount of styrene was changed to 28.5 g, and 1.5 g of acrylonitrile was used instead of methyl methacrylate to obtain a resinous styrene-acrylonitrile-compound [IA] copolymer. The polymerization rate was 94%, and the weight fraction composition was 95.13 wt% styrene, 4.82 wt% acrylonitrile, and 0.05 wt% compound [IA]. The Mw was 3.60 × 10 5 , Mz is 1.91 x 10 6 and Mz / Mw was 5.3.

[0065] Comparative Example 8 In Example 6, compound [IA] was not used, and a resinous styrene-acrylonitrile copolymer was obtained. The polymerization rate was 91%, the weight fraction composition was 95.06% by weight of styrene and 4.94% by weight of acrylonitrile, and the Mw was 3.65 × 10 5 , Mz is 1.75 x 10 6 and Mz / Mw was 4.8.

[0066] Example 7 In Example 6, the amount of styrene was changed to 27.0 g and the amount of acrylonitrile to 3.0 g, respectively, to obtain a resinous styrene-acrylonitrile-compound [IA] copolymer. The polymerization rate was 94%, and the weight fraction composition was 89.97 wt% styrene, 9.94 wt% acrylonitrile, and 0.09 wt% compound [IA]. The Mw was 3.75 × 10 5 , Mz is 2.04 x 10 6 and Mz / Mw was 5.4.

[0067] Comparative Example 9 In Example 7, compound [IA] was not used, and a resinous styrene-acrylonitrile copolymer was obtained. The polymerization rate was 91%, the weight fraction composition was 90.23% by weight of styrene and 9.77% by weight of acrylonitrile, and the Mw was 3.90 × 10 5 , Mz is 1.77 x 10 6 and Mz / Mw was 4.55.

[0068] Example 8 In Example 1, the amount of styrene was changed to 29.4 g, and 0.6 g of methacrylic acid was further added to obtain a resinous copolymer of styrene, methacrylic acid, and compound [IA]. The polymerization rate was 87%, and the weight fraction composition was 98.12 wt% styrene, 1.78 wt% methacrylic acid, and 0.10 wt% compound [IA]. The Mw was 4.96 x 10 5 , Mz is 2.14 x 10 6 and Mz / Mw was 4.3.

[0069] Comparative Example 10 In Example 8, compound [IA] was not used, and a resinous copolymer of styrene and methacrylic acid was obtained. The polymerization rate was 91%, the weight fraction composition was 98.06% by weight of styrene and 1.94% by weight of methacrylic acid, and the Mw was 4.06×10 5 , Mz is 1.85 x 10 6 and Mz / Mw was 4.5.

[0070] Example 9 A 300 ml four-neck flask equipped with a magnetic stirrer, thermometer, condenser, nitrogen gas inlet, and outlet tubes was charged with 30 g of styrene, 30 mg of compound [IA], 60 ml of cyclohexane, and 1 ml of tetrahydrofuran. 0.2 ml of sec-butyllithium (1.3 M) was added to initiate the polymerization reaction under a nitrogen atmosphere, and the temperature of the contents rose from 5°C to 70°C. One hour after the start of the polymerization reaction, 0.5 ml of methanol was added to terminate the polymerization, and the polymerized solution was added to methanol to coagulate the copolymer. The mixture was then dried under reduced pressure at 100°C for 2 hours, yielding 30 g of a colorless resinous styrene-compound [IA] copolymer.

[0071] The weight fraction composition of the copolymer was determined in the same manner as in Example 1, and it was found that the compound [IA] was 0.09% by weight and styrene was 99.91% by weight. The number average molecular weight (Mn) was 2.20 × 10 5 , weight average molecular weight (Mw) is 2.54 × 10 5 and Mw / Mn was 1.15.

[0072] Comparative Example 11 In Example 9, the compound [IA] was not used, and 30 g of a resinous styrene homopolymer was obtained. Mn was 2.49 × 10 5 , Mw is 2.96 x 10 5 and Mw / Mn was 1.19.

[0073] The resins or resin compositions obtained in each of the Examples and Comparative Examples were used to measure the melt flow rate (MFR), yellowness index (YI) and thermal stability. MFR: JIS K 7210-1 compliant, measured at 200°C and a load of 5.0 kg (However, in Example 8 and Comparative Example 10, measurements were taken with a load of 7.2 kg.) YI: A 30mm x 50mm, 1mm thick plate is placed in an air-circulating oven at 150°C. After heating for 1 hour, the color was measured using a Nippon Denshoku Industrial Co., Ltd. colorimeter ZE6000 in accordance with ASTM D1925. Measurement Thermal stability: The top edge of a circular plate with a diameter of 30 mm and a thickness of 2 mm is clamped with a clip (scissors The specimens were heated in an air-circulating oven at 140°C. As the test progresses, the test piece gradually melts and deforms, and the time it takes for the test piece to come off the clip and fall is measured. fixed

[0074] The above results are shown in the following Tables 1 to 3. Table 1 Measurement items Fruit 1 Fruit 2 Fruit 3 ratio 1 ratio 2 ratio 3 ratio 4 ratio 5 MFR (g / 10 min) 8.6 14.9 8.9 23.8 10.2 11.2 10.2 19.1 YI Before heating test -2.7 -3.7 -0.3 -2.7 -3.3 -2.7 -3.2 3.3 After heating test 1 day 0.5 -0.7 0.7 9.6 0.6 0.4 9.0 0.1 2nd -3.2 -1.0 1.5 17.0 -2.4 -1.3 16.6 3.2 3 days 1.1 1.4 3.6 30.0 1.9 1.8 20.9 2.8 4 days 1.6 1.8 4.4 36.4 2.4 0.4 22.5 5.1 5th -2.7 -2.9 0.2 46.7 -0.4 -2.2 24.8 6.6 6th 0.9 -0.3 2.3 56.5 3.9 0.0 27.8 6.2 Thermal stability (hours) 280 260 170 20 240 200 180 200 Table 2 Measurement items Fruit 4 ratio 6 Fruit 5 ratio 7 Fruit 6 ratio 8 Fruit 7 ratio 9 Fruit 8 ratio 10 MFR (g / 10 min) 9.4 24.7 9.0 22.6 18.6 23.2 13.7 21.1 10.9 * 18.5 * YI Before heating test 0.8 -1.7 -0.9 -2.0 -1.7 -1.0 -3.4 -1.5 -6.8 -2.2 After heating test 1 day 0.4 8.2 0.6 6.7 3.0 22.5 0.4 32.1 -3.7 13.6 2nd -1.2 13.6 -0.4 13.7 -1.8 34.4 3.0 48.0 -3.3 35.8 3 days -0.7 20.9 0.0 18.5 3.3 44.2 3.1 55.9 2.5 52.7 4 days 2.9 23.7 2.1 23.2 1.3 44.1 5.8 60.3 6.8 66.1 5 days 4.0 33.1 3.9 35.4 2.8 60.2 8.1 64.0 3.3 65.4 6th 3.2 46.6 3.8 42.2 6.0 65.3 6.3 81.9 6.1 110.9 Thermal stability (hours) 180 10 70 20 150 20 120 20 500 ** 80 *Measured with a 7.2kg load **Over 500 hours Table 3 Measurement items Fruit 9 ratio 11 MFR (g / 10 min) 3.7 2.3 YI Before heating test 0.8 1.4 After heating test 5th 1.3 12.4 10th 3.3 25.6

[0075] From the above results, the following can be said: (1) In Examples 1 to 8, copolymerization of the phenothiazine derivative compound [I] by radical polymerization makes it possible to suppress the decrease in melt viscosity (increase in MFR) of the resinous polymer caused by the thermal history in the post-treatment process. Moreover, under thermal oxidation degradation conditions, yellowing of the resinous molded product is suppressed and its thermal stability is improved. (2) When the phenothiazine derivative compound [I] was added to a polystyrene resin (Comparative Example 4), the effect of suppressing the increase in MFR was observed, but the yellowing of the resin due to heat was significant. (3) When the phenothiazine compound (a) was added to the polystyrene resin (Comparative Example 5), the effect of suppressing the increase in MFR was poor. (4) Example 9 shows that the phenothiazine derivative compound [I] can be easily copolymerized with styrene by anionic polymerization. Furthermore, copolymerization of the phenothiazine derivative compound [I] can suppress yellowing of styrene resin molded articles under thermal oxidative degradation conditions.

Claims

1. (A) 69 to 99.99% by weight of a styrene-based monomer, (B) a compound of the general formula (where R 1 is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and R 2 is a hydrogen atom or a methyl group) and (C) 0 to 30% by weight of a monomer consisting of at least one of an alkyl (meth)acrylate monomer, an aralkyl (meth)acrylate monomer, an α,β-ethylenically unsaturated carboxylic acid monomer, and a nitrile group-containing polymerizable unsaturated monomer.

2. 2. The styrenic copolymer according to claim 1, wherein the styrenic monomer (A) is styrene.

3. 3. The styrene copolymer according to claim 2, which does not contain the monomer (C).

4. 3. The styrene copolymer according to claim 2, wherein the monomer (C) is methyl methacrylate.

5. 3. The styrene copolymer according to claim 2, wherein the monomer (C) is acrylonitrile.

6. 3. The styrene copolymer according to claim 2, wherein the monomer (C) is methacrylic acid.

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