TWI788600B - Polymethacrylate composition and optical device made therefrom, and display apparatus - Google Patents

Abstract

A polymethacrylate composition, an optical device made therefrom, and a display apparatus are provided. The polymethacrylate composition includes 50 to 85 parts by weight of methacrylate series polymer, 15 to 50 parts by weight of styrene series-maleic anhydride series copolymer, and an aromatic compound with phosphite group. The methacrylate series polymer includes methacrylate series monomer unit and acrylate series monomer unit, and has weight average molecular weight (Mw) of 20,000 to 200,000. The styrene series-maleic anhydride series copolymer includes from 65wt% to 85wt% of styrene series monomer unit, from 15wt% to 35wt% of maleic anhydride series monomer unit, and from 0 to 20wt% of second copolymerizable monomer unit. The content range of the aromatic compound with phosphite group is from 200ppm to 900ppm based on 100 parts by weight of the methacrylate series polymer and the styrene series-maleic anhydride series copolymer.

Description

Polymethacrylate composition and its formed optical element and display device

The present invention relates to a polymer composition, and in particular to a polymethacrylate composition, an optical element and a display device formed therefrom.

Polymethacrylate (polymethacrylate) is a polymer with a wide range of uses. It has good evaluations in terms of processability, physical properties and mechanical properties. Its light transmittance is equivalent to that of glass, and its molded products have a good appearance. Therefore, it has become the most One of the excellent polymer transparent materials, and is often used in various optical components or consumer goods, such as camera lenses, lenses, optical films, car taillights, billboards, etc.

In recent years, with the development of thin and lightweight notebook computers, the requirements for thinner and higher performance optical components in display devices such as liquid crystal display devices have also increased. Moreover, as the application environments of liquid crystal display devices become more extensive, the optical elements are also required to have durability properties such as heat resistance in high-temperature environments and moisture resistance in high-humidity environments.

Although polymethacrylate has excellent optical properties and processability, it is somewhat insufficient in heat resistance. Therefore, how to make polymethacrylate both have good optical properties and heat resistance is a subject that needs to be improved in this field. In addition, during subsequent processing and molding, high-temperature thermal processes are likely to cause polymethacrylate compositions to produce Deterioration or yellowing, or even appearance defects, will make the polymethacrylate composition unable to fully display its original good optical properties.

The present invention provides a polymethacrylate composition and an optical element formed from the aforementioned composition, which can combine the heat resistance and optical properties of the polymethacrylate composition and a display device with the aforementioned optical element.

The polymethacrylate composition of the present invention comprises 50 to 85 parts by weight of methacrylate polymers, 15 to 50 parts by weight of styrene-maleic anhydride copolymers and phosphite group Aromatic compounds. The methacrylate polymer includes methacrylate monomer units and acrylate monomer units, and has a weight average molecular weight (Mw) of 20,000 to 200,000. The styrene-maleic anhydride copolymer comprises 65wt%~85wt% of styrene monomer units, 15wt%~35wt% of maleic anhydride monomer units and 0~20wt% of the second copolymerizable single unit. The total amount of the methacrylate polymer and the styrene-maleic anhydride copolymer is 100 parts by weight, and the content of the aromatic compound with a phosphite group is in the range of 200ppm to 900ppm .

In one embodiment of the present invention, the methacrylate polymer comprises 92wt%~99wt% of the methacrylate monomer unit, 1wt%~8wt% of the acrylate monomer unit and 0~7wt% of the first copolymerizable monomer unit, and the weight average molecular weight (Mw) of the methacrylate polymer is 50,000 to 150,000.

In an embodiment of the present invention, the ratio of the weight percent of styrene-based monomer units to the weight percent of maleic anhydride-based monomer units of the above-mentioned styrene-maleic anhydride-based copolymer is 1-8.5.

In an embodiment of the present invention, the weight average molecular weight (Mw) of the styrene-maleic anhydride copolymer is 60,000 to 100,000.

In an embodiment of the present invention, the molecular weight distribution index (PDI) of the styrene-maleic anhydride copolymer ranges from 1.5 to 2.05.

In an embodiment of the present invention, the polymethacrylate composition is also antioxidant, wherein the content ratio of the antioxidant to the aromatic compound with phosphite groups is in the range of 1.1-10.

In an embodiment of the present invention, the polymethacrylate composition may further include 500 ppm to 2000 ppm of antioxidant.

In an embodiment of the present invention, the polymethacrylate composition may further include 500 ppm to 2000 ppm of heat stabilizer.

In an embodiment of the present invention, the above-mentioned polymethacrylate composition may further include a UV absorber, wherein the content ratio of the UV absorber to the aromatic compound with phosphite groups ranges from 10 to 300.

In an embodiment of the present invention, the above-mentioned polymethacrylate composition may further include 10000 ppm to 50000 ppm of an ultraviolet absorber, and the flash point of the ultraviolet absorber is ≧240°C.

In one embodiment of the present invention, the above-mentioned ultraviolet absorber is selected from 2-(4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)- 5-octyloxyphenol, 2,2'-methylenebis[6-(benzotriazol-2-yl)-4-tert-octylphenol], 2-(4,6-diphenyl-1 ,3,5-Triazin-2-yl)-5-[(hexyl)oxy]-phenol, 2,2',4,4'-tetrahydroxybenzophenone, 3-[(2-cyano -3,3-diphenylacryloyl)oxy]-2,2-bis{[(2-cyano-3,3-diphenylacryloyl)oxy]methyl}propyl 2-cyano-3 ,3-diphenylacrylate, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol, 2-(2'-hydroxy-3',5'- At least one of the group consisting of dipentylphenyl)benzotriazole. The optical element of the present invention is formed of the above-mentioned polymethacrylate composition.

In an embodiment of the present invention, the optical element is at least one selected from the group consisting of an optical plate, an optical sheet, and an optical film.

The display device of the present invention includes the above-mentioned optical element, and the display device is selected from a TV, a digital camera, a digital video camera, a digital photo frame, a mobile phone, a notebook personal computer, a mobile computer, a screen for a computer, etc. , a portable game machine, a portable information terminal, an audio reproduction device, a game machine, and a vehicle display at least one of the group.

Based on the above, the polymethacrylate composition of the present invention has a specific composition and these compositions have a specific ratio, so it can have excellent heat resistance, thermal stability and optical properties at the same time, so it can be applied to optical elements and has low fog Excellent optical properties with low yellowness and low yellowness. A display device having the above-mentioned optical element also has an excellent display effect.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific examples are given and described in detail as follows.

Hereinafter, embodiments of the present invention will be described in detail. However, these embodiments are illustrative, and the present disclosure is not limited thereto.

In one embodiment of the present invention, the polymethacrylate composition includes 50 to 85 parts by weight of methacrylate polymer, 15 to 50 parts by weight of styrene-maleic anhydride copolymer and Aromatic compounds with phosphate groups. The methacrylate polymer includes methacrylate monomer units and acrylate monomer units and has a weight average molecular weight (Mw) of 20,000 to 200,000. The styrene-maleic anhydride copolymer comprises 65wt%~85wt% of styrene monomer units, 15wt%~35wt% of maleic anhydride monomer units and 0~20wt% of the second copolymerizable single unit. The content of the aromatic compound with phosphite groups ranges from 200ppm to 900ppm.

Methacrylate polymer

Methacrylate polymers are mainly polymerized from monomer mixtures mainly composed of methacrylate monomers. In one embodiment, the methacrylate polymer is polymerized from a mixture of methacrylate monomers and acrylate monomers, and its weight average molecular weight (Mw) is 20,000 to 200,000. For example, it is 50,000 to 150,000, or 70,000 to 110,000; preferably, the methacrylate polymer is composed of a methacrylate monomer, an acrylate monomer and a first copolymerizable monomer. aggregated from a mixture of bodies.

Specific examples of methacrylate monomers include, but are not limited to: methyl methacrylate (methyl methacrylate), ethyl methacrylate, propyl methacrylate, n-butyl methacrylate (n-butyl methacrylate), Amyl methacrylate, cyclohexyl methacrylate, heptyl methacrylate, n-octyl methacrylate, octadecyl methacrylate, phenyl methacrylate, methacrylic acid Benzyl ester or 2-ethylhexyl methacrylate (2-ethylhexyl methacrylate), etc., and the above monomers can be used alone or in combination.

Specific examples of acrylate monomers include, but are not limited to: methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, heptyl acrylate, dodecyl acrylate Base ester, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate (2-ethylhexyl acrylate), octadecyl acrylate, etc. The above-mentioned monomers may be used alone or in combination.

Specific examples of the first copolymerizable monomer include, but are not limited to: (1) unsaturated carboxylic acid monomers, such as but not limited to acrylic acid, methacrylic acid, maleic acid, itaconic acid, citric acid citraconic acid, or aconitic acid, etc.; (2) maleimide-based monomers, such as but not limited to maleimide, nitrogen-methylmaleimide, nitrogen-isopropyl arylmaleimide, nitrogen-butylmaleimide, nitrogen-hexylmaleimide, nitrogen-octylmaleimide, nitrogen-dodecylmaleimide, nitrogen-cyclic Hexylmaleimide, nitrogen-phenylmaleimide, nitrogen-2,3-tolylmaleimide, nitrogen-2,4-tolylmaleimide, nitrogen-2,3 -Ethylphenylmaleimide, nitrogen-2,4-ethylphenylmaleimide, nitrogen-2,3-butylphenylmaleimide, nitrogen-2,4-butylphenylmaleimide Nitrogenimide, Nitrogen-2,6-Tolylmaleimide, Nitrogen-2,3-Chlorophenylmaleimide, Nitrogen-2,4-Chlorophenylmaleimide, Nitrogen -2,3-bromophenylmaleimide, nitrogen-2,4-bromophenylmaleimide, etc.; (3) propenyl-containing compound monomers, such as but not limited to acrylamide ), acrylonitrile, α-methacrylonitrile, allyl glycidyl ether or glycidyl (meth)acrylate; (4) containing Vinyl compound monomers, such as but not limited to vinyl acetate or chloroethene; (5) styrenic monomers, such as but not limited to styrene, 2-chlorostyrene, 4-chloro Styrene, bromostyrene, vinyl toluene, α-methylstyrene, p-tert-butylstyrene, p-methylstyrene, o-methylstyrene, m-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, etc. The above-mentioned monomers may be used alone or in combination.

Preferably, the methacrylate polymer includes a methacrylate monomer unit, an acrylate monomer unit and a first copolymerizable monomer unit. The term "monomer unit" here refers to the repeating structure formed by the polymerization reaction of the aforementioned methacrylate monomer, acrylate monomer or first copolymerizable monomer.

In one embodiment, the methacrylate polymer contains 92% by weight (wt%)-99wt% of methacrylate-based monomer units and 1wt%-8wt% of acrylate-based monomer units. In addition, the methacrylate polymer may optionally include 0-7 wt% of the first copolymerizable monomer unit.

In another embodiment, the content of the acrylate monomer unit of the methacrylate polymer is 2wt%~6wt%, such as 3wt%~6wt%, 3.5wt%~5.5wt%, or 4wt% %~5.5wt%.

In one embodiment, the weight average molecular weight (Mw) of the methacrylate polymer is 50,000 to 150,000, such as 60,000 to 140,000 or 70,000 to 130,000.

In another embodiment, the weight average molecular weight (Mw) of the methacrylate polymer is 70,000-95,000, such as 75,000-95,000, 80,000-95,000, 85,000-95,000.

The methacrylate polymer can be prepared by a solution or block polymerization method, and the polymerization reaction is preferably carried out in the presence of a solvent to avoid difficult control of the polymerization reaction due to the increase in the viscosity of the crude polymer. The viscosity of the methacrylate polymer is usually represented by the solid content, and the amount of solvent used should be adjusted so that the solid content of the crude polymer is lower than 50 wt%, or preferably lower than 40 wt%.

If the boiling point of the above-mentioned solvent is close to that of the main monomer to be polymerized, the mixture formed by the solvent and the monomer will have a narrower boiling point range, thereby reducing the chance of contamination in the recycled mixture, and at the same time The step of intermediate fractionation for the recycled monomer and solvent mixture is eliminated. For example, a solvent with a boiling point close to that of the methacrylate monomer can be selected. Preferably, the solvent has a boiling point of 40°C to 225°C; more preferably, it has a boiling point of 60°C to 150°C boiling point. Specific examples of the above-mentioned solvents include, but are not limited to: hexane, heptane, octane, benzene, toluene, p-xylene, o-xylene, m-xylene, ethylbenzene, cyclohexane, cyclodecane, isooctane, Or various low boiling hydrocarbon or aromatic hydrocarbon solvents. The aforementioned solvents may be used alone or in combination.

The polymerization reaction of the methacrylate polymer is initiated by a free radical initiator, and the free radical initiator is not particularly limited, and specific examples include but are not limited to: (1) Azo compounds: such as 2, 2'-Azobisisobutyronitrile [2,2'-azobis- (isobutyronitrile), referred to as AIBN], 2,2'-azobis (2-methylbutyronitrile) [2,2'-azobis- (2-methylbutyronitrile), referred to as AMBN], 2,2'- azobis (2,4-dimethylvaleronitrile) [2,2'-azobis-(2,4-dimethylvaleronitrile), referred to as ADVN] etc.; (2) diacyl peroxides compounds: such as dilauroyl peroxide, decanoyl peroxide, dibenzoyl peroxide (BPO for short) ), etc.; (3) dialkyl peroxides compounds: such as 2,5-dimethyl-2,5-tertiary butylperoxyhexane [2,5-dimethyl-2,5-di -(t-butylperoxy)hexane], dicumyl peroxide (dicumyl peroxide), 1,3-bis(tertiary butylperoxyisopropyl) benzene[1,3-bis-(t-butyl peroxy isopropyl ) benzene], etc.; (4) peroxyesters compounds: such as t-butylperoxypivalate (t-butylperoxypivalate), 2,5-dimethyl-2,5-bis(2- Ethylhexyl peroxy) hexane [2,5-dimethyl-2,5-di(2-ethyl hexanoylperoxy) hexane], etc.; (5) peroxycarbonates (peroxycarbonates) compounds: such as 2-ethylhexyl Tert-amylperoxy 2-ethylhexyl carbonate, 2-ethylhexyl tert-butyl peroxycarbonate (tert-butylperoxy 2-ethylhexyl carbonate), etc.; (6) peroxydicarbonate (peroxydicarbonates) compounds: such as dimyristyl peroxydicarbonate (dimyristyl peroxydicarbonate), di(4-tert-butylcyclohexyl) peroxydicarbonate [di(4-tert-butylcyclohexyl peroxydicarbonate)], etc.; (7) peroxyketal Alcohol (peroxyketal) compounds: such as 1,1-di(tert-butylperoxy) 3,3,5-trimethylcyclohexane [1,1-di(tert-butylperoxy)-3,3,5 -trimethylcyclohexane], 2,2-bis(4,4-bis(tert-butyl peroxy)cyclohexyl) propane [2,2-di(4,4-di(tert-butyl peroxy)cyclohexyl) propane], etc. ; (8) Hydroperoxides: such as t-butyl hydroperoxide, isopropylcumyl hydroperoxide, etc.; (9) Others: 2 ,3-Dimethyl-2,3-diphenylbutane (2,3-dimethyl-2,3-diphenyl-butane), potassium persulfate (potassium persulfate), sodium persulfate (sodium persulfate), persulfate Ammonium (ammonium persulfate), etc. Preferably, the free radical initiator is 2,2'-azobisisobutylnitrile. Based on 100 parts by weight of the total amount of the monomer mixture fed in, the usage amount of the free radical initiator can be 0.01 to 1 part by weight, preferably 0.03 to 0.5 parts by weight, more preferably 0.07 to 0.07 parts by weight. 0.1 parts by weight.

The polymerization reaction for preparing methacrylate polymer can be carried out at normal temperature, but in order to increase the polymerization speed, the reaction system can be heated. The general reaction temperature is about 5°C to 200°C, the preferred reaction temperature is 20°C to 130°C, and the more preferred reaction temperature is 30°C to 100°C. During the polymerization reaction, a chain transfer agent can be added as needed to facilitate the control of molecular weight; the chain transfer agent is for example but not limited to: n-dodecyl mercaptan (n-dodecyl mercaptan, NDM for short), stearyl Mercaptan (stearyl mercaptan), t-dodecyl mercaptan (t-dodecyl mercaptan, TDM for short), n-propyl mercaptan, n-octyl mercaptan, third-octyl mercaptan, third - Nonylmercaptan or terpinolene, etc.

Styrene - Maleic anhydride copolymer

A styrenic-maleic anhydride copolymer is any polymer comprising a styrenic monomer, a maleic anhydride monomer, and a second copolymerizable monomer, such as linear or branched random copolymers compounds, linear or branched block copolymers, or mixtures thereof.

In one embodiment, the styrene-maleic anhydride copolymer is polymerized from a mixture comprising a styrene monomer, a maleic anhydride monomer, and a second copolymerizable monomer.

The above-mentioned maleic anhydride-based monomers can be used alone or in combination, and the maleic anhydride-based monomers are, for example but not limited to, maleic anhydride, itaconic anhydride, citraconic anhydride, or aconitic anhydride. Preferably, the maleic anhydride-based monomer is maleic anhydride.

The above-mentioned styrenic monomers can be used alone or in combination, and styrenic monomers such as but not limited to styrene, (1) halogen-substituted styrene such as but not limited to 2-chlorostyrene, 4-chlorostyrene or Bromostyrene, etc.; (2) Alkyl-substituted styrenes such as but not limited to vinyl toluene (vinyl toluene), α-methylstyrene (α-methylstyrene), p-tertiary butylstyrene, p- -Methylstyrene, o-methylstyrene, m-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, etc. In one embodiment, the styrenic monomer is at least one selected from the group consisting of styrene, halogen-substituted styrene, and alkyl-substituted styrene. In one embodiment, the styrenic monomer is at least one selected from the group consisting of styrene and α-methylstyrene.

The second copolymerizable monomers for polymerizing styrene-maleic anhydride copolymers can be used alone or in combination, and the second copolymerizable monomers are, for example but not limited to, selected from the group as described above for methacrylate The methacrylate-based monomer and the acrylate-based monomer of the polymer constitute a group, so details will not be repeated here.

Preferably, the styrene-maleic anhydride copolymer includes styrene monomer units, maleic anhydride monomer units and a second copolymerizable monomer unit. The term "monomer unit" here refers to the repeating structure formed by the polymerization reaction of the aforementioned styrene-based monomer, maleic anhydride-based monomer or the second copolymerizable monomer. Accordingly, the styrenic monomer unit is derived from the above-mentioned styrene-based monomer, the maleic anhydride-based monomer unit is derived from the above-mentioned maleic anhydride-based monomer, and the second copolymerizable monomer unit is derived from the above-mentioned second copolymerizable monomer unit. monomer.

In one embodiment, the styrene-maleic anhydride copolymer comprises 65wt%~85wt% of styrene monomer units, 15wt%~35wt% of maleic anhydride monomer units and 0~20wt% of Two copolymerizable monomer units.

In another embodiment, the content of the styrene monomer unit in the styrene-maleic anhydride copolymer is 65wt%~85wt%; preferably 65wt%~81wt%; more preferably 66wt% ~ 77wt%, when the content of styrene-based monomer units is higher than 65wt%, it will make the polymethacrylate composition of styrene-maleic anhydride copolymers containing such styrene-based monomer units The product has good light transmittance (T%), haze (HAZE) and yellowness (YI) performance; when the content of styrene monomer units is below 85wt%, it will make styrene-maleic anhydride The content of maleic anhydride monomer unit in the copolymer is more than 15wt%, therefore, the polymethacrylate composition that contains this kind of styrene-maleic anhydride copolymer can have good heat resistance (glass transition temperature , Tg).

In one embodiment, the content range of the styrene monomer unit in the styrene-maleic anhydride copolymer is 65wt%~81wt% and the content range of the maleic anhydride monomer unit is 19wt%~ 35wt%, polymethacrylate compositions containing such a proportion of styrene-maleic anhydride copolymers can be used in optical elements with high heat resistance requirements, preferably, such a proportion of styrene-maleic anhydride -The molecular weight distribution index (PDI) of maleic anhydride copolymers ranges from 1.5 to 2.05, which can maintain good light transmittance (T%), haze (HAZE) and yellowness (YI) while maintaining high performance Heat resistant performance.

In one embodiment, the weight percent ratio of styrene-based monomer units to maleic anhydride-based monomer units in the styrene-maleic anhydride copolymer is between 1 and 8.5; preferably between 1.3 and 8 Between; more preferably 1.5~7.

In one embodiment, the weight average molecular weight (Mw) of the styrene-maleic anhydride copolymer is 60,000-100,000, preferably 65,000-95,000, more preferably 65,000-90,000.

In one embodiment, the number average molecular weight (Mn) of the styrene-maleic anhydride copolymer is 30,000-55,000, preferably 35,000-50,000, more preferably 37,000-48,000.

In one embodiment, the range of molecular weight distribution index (PDI) of styrene-maleic anhydride copolymer is 1.5~2.05, preferably 1.7~2.0, more preferably 1.7~1.9, when styrene-maleic anhydride copolymer When the molecular weight distribution index (PDI) of the maleic anhydride-based copolymer is greater than 2.05, the optical properties (low haze) of the polymethacrylate composition containing the styrene-maleic anhydride-based copolymer of this molecular weight distribution index will be reduced. and low yellowness) worse.

The polymerization method of the styrene-maleic anhydride copolymer is not particularly limited, and may be free radical polymerization using a free radical initiator. Sufficient transparency may not be obtained by the method obtained by suspension polymerization and emulsion polymerization. The free radical initiator used is, for example but not limited to, selected from the free radical initiators used for methacrylate polymers mentioned above, so details are not repeated here.

Based on 100 parts by weight of monomers in total, the addition amount of the radical initiator is preferably 0.001 to 5 parts by weight. A small amount of solvent can also be used during polymerization, such as aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane, octane, and isooctane; cyclopentane, methylcyclopentane, cyclohexane Alicyclic hydrocarbons such as alkane, methylcyclohexane, ethylcyclohexane, etc.; or aromatic hydrocarbons such as benzene, toluene, ethylbenzene, xylene, etc. In addition, known molecular weight modifiers such as 4-methyl-2,4-diphenylpent-1-ene, tert-dodecylmercaptan, and n-dodecylmercaptan may be added during polymerization. The polymerization temperature is preferably 80°C to 170°C, more preferably 100°C to 160°C.

With phosphite group aromatic compounds

The use of aromatic compounds with phosphite groups can prevent the maleic anhydride ring-opening of the styrene-maleic anhydride copolymer in the high-temperature process, which will change the composition of the polymethacrylate composition and affect the composition. Heat resistance (lower Tg), thermal stability (lower Td) and optical properties (haze and yellowness) of the product.

Aromatic compounds with phosphite groups, specific examples include but are not limited to: tris(2,4-di-tert-butylphenyl) phosphite, bis[2,4-bis(1,1 -Dimethylethyl)-6-methylphenyl]ethyl ester, tetrakis(2,4-di-tert-butylphenol)-4,4'-biphenyl diphosphite, bis(2,4 -di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2,4-dicumyl phenyl) pentaerythritol diphosphite, di-tert-butyl m-tolyl phosphite, etc., and the above compounds can be used alone or in combination.

式(1)In one embodiment, the aromatic compound having a phosphite group is preferably a heterocyclic aromatic phosphite compound containing a pentaerythritol diphosphite group, such as a structure having the following formula (1).

Formula 1)

In the above formula, R ₁ and R ₂ each independently represent hydrogen or C1-C10 straight-chain alkyl, branched-chain alkyl, cyclic alkyl or a combination thereof. For example, it is selected from hydrogen, methyl or tert-butyl. Specific examples of aromatic compounds with phosphite groups include, but are not limited to: bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl -4-methylphenyl) pentaerythritol diphosphite, bis(2,4-dicumylphenyl) pentaerythritol diphosphite.

If the total amount of the methacrylate polymer and the styrene-maleic anhydride copolymer is 100 parts by weight, the aromatic phosphite group in the polymethacrylate composition The content of the compound is 200ppm to 900ppm; preferably 250ppm to 800ppm; more preferably 300ppm to 800ppm. When the content of the aromatic compound with phosphite group is within this range, the polymethacrylate composition containing the aromatic compound with phosphite group can have high Tg (good heat resistance), high Td (good thermal stability) and better optical performance (low yellowness and low haze). The content of the aforementioned aromatic compounds with phosphite groups is generally measured when the total amount of polymers in the polymethacrylate composition is 100 parts by weight, that is, the methacrylate polymer and the The total amount of the styrene-maleic anhydride copolymer is 100 parts by weight.

In addition, any additives may be mixed according to various purposes within a range not significantly impairing the effect of the present invention. The types of these additives are not particularly limited, as long as they are generally used in resin compositions or rubber compositions, for example: antioxidants, heat stabilizers, ultraviolet absorbers, slip agents, processing aids, fillers, reinforcing agents, Colorant, antistatic agent, or other additives, etc., the above-mentioned additives are not limited to be added during the polymerization reaction, after the polymerization reaction, or during extrusion kneading. The content of additives is generally calculated when the total amount of polymers in the polymethacrylate composition is 100 parts by weight, that is, based on the amount of methacrylate polymers and styrene-maleic anhydride copolymers The total amount is 100 parts by weight.

Antioxidants

Antioxidants are additives other than the aforementioned aromatic compounds with phosphite groups. Specific examples include but are not limited to: pentaerythritol tetrakis [3-(3,5-di-tertiary-butyl-4-hydroxyphenyl) propionate], octadecyl-3-(3,5-di-tertiary-butyl-4-hydroxyphenyl)propionate, β-(3,5-di-tert-butyl-4- Hydroxyphenyl)propionate isooctyl, triethylene glycol ether-di(3-tert-butyl-4-hydroxy-5-methylphenyl)propanoic acid, 3,5-di-tert-butyl-4 -Hydroxycinnamic acid, 3,9-bis(1,1-dimethyl-2-hydroxyethyl-2,4,8,10-tetraoxaspiro(5,5)undecane, 3,9- Bis(2-(3-(3-tertiary-butyl-4-hydroxy-5-methylphenyl)propionyloxy)-1,1-dimethylethyl)-2,4,8, 10-tetraoxaspiro(5,5)undecane, etc., and the above antioxidants can be used alone or in combination.

式(2)In one embodiment, the antioxidant is preferably a phenolic compound having a 2,4,8,10-tetraoxaspiro(5,5)undecyl group, such as a compound having the structure of the following formula (2).

Formula (2)

In the above formula, R _a and R _b each independently represent a C6~C12 alkyl group, an ether group, an ester group or a combination thereof; _R3 and _R4 each independently represent hydrogen or a straight chain of C1~C10, Branched or cyclic alkyl. Specific examples of antioxidants include, but are not limited to: 3,9-bis(2-(3-(3-tertiary-butyl-4-hydroxy-5-methylphenyl)propionyloxy)-1,1 -Dimethylethyl)-2,4,8,10-tetraoxaspiro(5,5)undecane.

The antioxidant content in the polymethacrylate composition ranges from 500 ppm to 2000 ppm, such as 700 ppm to 1700 ppm or 850 ppm to 1600 ppm. In one embodiment, when the polymethacrylate composition has antioxidants and aromatic compounds with phosphite groups at the same time, and the content ratio of the antioxidants to aromatic compounds with phosphite groups ranges from 1.1 to 10. For example, when it is 1.2~8.5 or 1.5~8, the polymethacrylate composition can not only have good heat resistance (high Tg) and good thermal stability (high Td), but also can make it have low fog degree of optical performance. In one embodiment, the polymethacrylate composition contains 500 ppm to 2000 ppm of antioxidant and 200 ppm to 900 ppm of aromatic compound with phosphite groups.

heat stabilizer

式(3)In one embodiment, the present invention can use general heat stabilizers. In another embodiment, the present invention can use a heat stabilizer represented by the following formula (3).

Formula (3)

In the above formula, R ₅ and R ₈ each independently represent hydrogen or a methyl group, and R ₆ and R ₇ each independently represent a C1-C9 linear, branched or cyclic alkyl group. R ₆ is, for example, selected from tertiary butyl or tertiary pentyl; R ₇ is, for example, selected from tertiary butyl, tertiary pentyl or tertiary octyl.

The heat stabilizer added in the polymethacrylate composition ranges from 500ppm to 2000ppm, within this range, thermal stability, processability and production cost can be controlled. In one embodiment, the added amount of the heat stabilizer in the polymethacrylate composition ranges from 700ppm to 1800ppm; in another embodiment, the added amount of the heat stabilizer in the polymethacrylate composition ranges from 900ppm to 1600ppm.

UV absorber

The UV absorber can be chosen to have a flash point higher than the processing temperature, for example, a UV absorber with a flash point greater than or equal to 240°C, so as to avoid the precipitation of the UV absorber during the high-temperature molding process of processing and forming optical components, which will cause severe damage. Dirt problem.

Specific examples of UV absorbers include, but are not limited to: 2-(4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-octyloxy 2-(4,6-Bis-(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-(octyloxy)-phenol), 2,2'-methylene Bis[6-(benzotriazol-2-yl)-4-tert-octylphenol] (2,2'-Methylenebis [6-(benzotriazol-2-yl)-4-tert-octylphenol]), 2- (4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol (2-(4,6-diphenyl-1,3,5- triazin-2-yl)- 5-[(hexyl)oxy]-phenol), 2,2',4,4'-tetrahydroxybenzophenone (2,2',4,4'- Tetrahydroxybenzophenone), 3 -[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis{[(2-cyano-3,3-diphenylacryloyl)oxy]methyl}propane 2-cyano-3,3-diphenylacryloyl (3-[(2-Cyano-3,3-diphenylacryloyl)oxy]-2,2-bis{[(2-cyano-3,3-diphenylacryloyl) oxy]methyl}propyl 2-cyano-3,3-diphenylacrylate, uvinul 3030), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (2-( 2H-Benzotriazol-2-yl)-6-dodecyl-4-methylphenol), 2-(2'-hydroxy-3',5'-dipentylphenyl)benzotriazole (2-(2'-Hydroxy -3',5'-dipentylphenyl)benzotriazole), etc., and the above ultraviolet absorbers can be used alone or in combination.

The content of the UV absorber in the polymethacrylate composition ranges from 10000ppm to 50000ppm, for example, 15000ppm to 40000ppm or 20000ppm to 35000ppm. In this range, the UV absorber can be mixed evenly with the composition, and the subsequent The heat processing process causes the ultraviolet absorber to precipitate out to produce mold contamination, and can make the composition have good ultraviolet light stability. In one embodiment, when the polymethacrylate composition contains an ultraviolet absorber and an aromatic compound with a phosphite group at the same time, and the content ratio of the ultraviolet absorber to the aromatic compound with a phosphite group is in the range of 10~300, such as 15~200 or 20~180, the polymethacrylate composition not only has good heat resistance (high Tg) and good thermal stability (high Td), but also can make it have Optical performance with low yellowness. In one embodiment, the polymethacrylate composition contains 10000 ppm to 50000 ppm of UV absorber and 200 ppm to 900 ppm of aromatic compound with phosphite groups.

lubricant

Specific examples of slip agents include, but are not limited to: metal soaps such as calcium stearate, magnesium stearate, and lithium stearate, ethylene distearamide, methylene distearamide, palmitamide, Butyl stearate, palmityl stearate, polypropionyl tristearate, n-docosanoic acid, stearic acid, stearyl alcohol and other compounds, polyethylene wax, octacosanoic acid wax, Carnuba wax, petroleum wax, etc., and the above slip agents may be used alone or in combination.

In the polymethacrylate composition, the amount of slip agent added is, for example, 300 ppm to 50000 ppm.

Processing aids

Specific examples of processing aids include but are not limited to: core-shell acrylate-based processing aids with a weight average molecular weight (Mw) of more than 500,000 to improve extrusion moldability and thermoformability.

antistatic agent

Specific examples of antistatic agents include, but are not limited to: low-molecular compounds such as tertiary amine compounds, quaternary ammonium salt compounds, or polyamide polyethers, such as 3-chloro-1,2-propylene oxide The permanent electrification prevention polymer system material of the body. The aforementioned antistatic agents can be used alone or in combination.

filler

Specific examples of fillers include, but are not limited to: calcium carbonate, silica, mica, etc., and the aforementioned fillers can be used alone or in combination.

enhancer

Specific examples of reinforcing agents include, but are not limited to: glass fibers, carbon fibers, various whiskers, etc., and the aforementioned reinforcing agents can be used alone or in combination.

Colorant

Specific examples of colorants include, but are not limited to: titanium oxide, iron oxide, graphite, phthalocyanine dyes, etc., and the aforementioned colorants can be used alone or in combination.

The use of the polymethacrylate composition of the present invention is not particularly limited, and it can be applied to molding such as injection molding, compression molding, extrusion molding, blow molding, thermoforming, vacuum forming, and hollow molding. Method, it can be made, for example: press board, film molding, etc., can be formulated according to the formula to achieve high fluidity, high thermal stability and other requirements.

The polymethacrylate composition can be obtained by general mixing and kneading machines such as Brabender Plastometer, Banbury kneading machine, kneader-mixer, rolling machine, single-shaft or twin-shaft extruder. Usually, after mixing and kneading by extruder, the extrudate is cooled and granulated. The polymethacrylate composition is generally kneaded at 160°C~280°C, preferably at 180°C~250°C. In addition, there is no particular restriction on the order of mixing and kneading of the components.

The optical element of another embodiment of the present invention is formed of the above-mentioned polymethacrylate composition, and has excellent optical properties of low haze and low yellowness. In one embodiment, the optical element may be an optical material with a planar structure, such as an optical plate, an optical sheet, or an optical film. In one embodiment, the preparation method of the planar optical material is not particularly limited here, the polymethacrylate composition can be melted through an extruder, and then extruded into a plate, sheet or film Shaped unstretched optical plate, optical sheet or optical film. In another embodiment, the aforementioned unstretched optical plate, optical sheet or optical film may also be stretched horizontally or biaxially at a temperature above its glass transition temperature by using a tenter.

In one embodiment, the optical element is, for example, an optical plate with a planar structure, which includes a sheet-shaped body, and the body includes a plane. Wherein, the body has a rectangular shape and is composed of the aforementioned polymethacrylate composition.

In another embodiment, the optical element is, for example, an optical plate with microstructures. Please refer to FIG. 1A , which is an optical plate 10 with a microstructure. The optical plate has a body 12 , the body includes a surface 122 , and a plurality of first microstructures 132 are disposed on the surface 122 . As shown in FIG. 1A , each first microstructure 132 in this embodiment is a pit structure, but the present invention is not limited thereto. In other embodiments, each first microstructure 132 can be a bump structure or a structure with other shapes.

Please refer to FIG. 1B, which illustrates another embodiment of an optical element, except for the first microstructure 132 of FIG. The side surface 126 of the surface 122 can also be provided with a second microstructure 134 , for example, a lens structure is provided on the surface 124 . Each of the second microstructures 134 in this embodiment is semi-circular, but the present invention is not limited thereto. In other embodiments, each second microstructure 134 can be a protruding structure with a suitable shape such as a prism or a corner column. In addition, the optical element can also be an optical plate with the second microstructure 134 alone.

In some embodiments, the optical element can be applied to various display devices. As the display device, TV sets (also known as televisions or television receivers) (as shown in Figure 2A), digital cameras (as shown in Figure 2B), digital video cameras (as shown in Figure 2C), digital photo frames (as shown in Figure 2D), mobile Telephones (as shown in Figure 2E), notebook personal computers, mobile computers, screens for computers, etc., portable game consoles, portable information terminals, audio reproduction devices, game consoles, and car displays.

The polymethacrylate composition of the present invention will be described in more detail below with reference to several experiments. Although the following experiments are described, materials used, their amounts and ratios, details of treatments, procedures of treatments, and the like can be appropriately changed without departing from the scope of the present invention. Therefore, the present invention should not be limitedly interpreted on the basis of the experiments described hereinafter.

>Raw materials used in Examples and Comparative Examples>

Preparation of methacrylate polymer 1:

First, mix 95 parts by weight of methyl methacrylate, 5 parts by weight of methyl acrylate, 0.4 parts by weight of n-dodecyl mercaptan, 0.08 parts by weight of 2,2'-azobisisobutyronitrile, and 66 parts by weight of toluene Afterwards, it is continuously sent to a reaction tank for continuous solution polymerization. The above-mentioned reaction tank is a sandwich structure with heat medium oil circulation, and the reaction temperature is maintained at 100°C and the pressure is 600 torr. Thoroughly stir the components in the reaction tank to make them evenly mixed, and after heating the obtained polymer solution to 265°C, the above-mentioned polymer solution is devolatilized by a continuous devolatilization device under reduced pressure, and then produced by extrusion equipment. into strips. After cooling and pelletizing, polymethyl methacrylate plastic particles are obtained. The polymethyl methacrylate plastic particles contain 97 wt% of methyl methacrylate monomer units and 3 wt% of methyl acrylate monomer units. The weight average molecular weight (Mw) of the polymethyl methacrylate plastic particles measured by GPC and using polystyrene as a standard is 100,000, and the melt flow rate (MVR) (230°C×3.8kg)=1.9.

Preparation of methacrylate polymer 2:

First, mix 94 parts by weight of methyl methacrylate, 6 parts by weight of methyl acrylate, 0.5 parts by weight of n-dodecyl mercaptan, 0.1 parts by weight of 2,2'-azobisisobutyronitrile, and 66 parts by weight of toluene Afterwards, it is continuously sent to a reaction tank for continuous solution polymerization. The above-mentioned reaction tank is a sandwich structure with heat medium oil circulation, and the reaction temperature is maintained at 100°C and the pressure is 600 torr. Thoroughly stir the components in the reaction tank to make them evenly mixed, and after heating the obtained polymer solution to 265°C, the above-mentioned polymer solution is devolatilized by a continuous devolatilization device under reduced pressure, and then produced by extrusion equipment. into strips. After cooling and pelletizing, polymethyl methacrylate plastic particles are obtained. The polymethyl methacrylate plastic particles contain 95.5 wt% of methyl methacrylate monomer units and 4.5 wt% of methyl acrylate monomer units. The weight average molecular weight (Mw) of the polymethyl methacrylate plastic particles measured by GPC and using polystyrene as a standard is 90,000, and the melt flow rate (MVR) (230°C×3.8kg)=3.0.

The preparation of styrene-maleic anhydride copolymer 1:

In a 40 L stirred reactor, 7440 g of maleic anhydride was added after being purged with nitrogen gas for 10 minutes, and the temperature was raised to 130° C., and then kept constant for 30 minutes. Then the temperature was still kept at 130°C, and a mixed solution containing 22,560g of styrene and 12g of 2,2'-azobisisobutyronitrile was continuously added within 1 hour, and then the temperature was lowered to 110°C after the feeding was completed, and the reaction was performed at constant temperature After 4 hours, the unreacted maleic anhydride was washed away with acetone, and the unreacted styrene was removed in a vacuum oven at 80°C to obtain a block-shaped styrene-maleic anhydride copolymer. The styrene-maleic anhydride copolymer contained 76.8 wt % of styrene-based monomer units and 23.2 wt % of maleic anhydride-based monomer units. Using GPC and using polystyrene as a standard, the number average molecular weight (Mn) was 37916, the weight average molecular weight (Mw) was 67250, and PDI=1.77.

The preparation of styrene-maleic anhydride copolymer 2:

In a 40 L stirred reactor, 9570 g of maleic anhydride was added after being purged with nitrogen gas for 10 minutes, and the temperature was raised to 130° C., and then kept constant for 30 minutes. Then the temperature was still kept at 130°C, and a mixed solution containing 20430g of styrene and 12g of 2,2'-azobisisobutyronitrile was continuously added within 1 hour, and then the temperature was lowered to 110°C after the feeding was completed, and the reaction was carried out at constant temperature After 4 hours, the unreacted maleic anhydride was washed away with acetone, and the unreacted styrene was removed in a vacuum oven at 80°C to obtain a block-shaped styrene-maleic anhydride copolymer. The styrene-maleic anhydride copolymer contained 67.9 wt% of styrene-based monomer units and 32.1 wt% of maleic anhydride-based monomer units. Using GPC and using polystyrene as a standard, the number average molecular weight (Mn) was 36560, the weight average molecular weight (Mw) was 65810, and PDI=1.80.

The preparation of styrene-maleic anhydride copolymer 3:

In a 40 L stirred reactor, 8190 g of maleic anhydride was added after being purged with nitrogen gas for 10 minutes, and the temperature was raised to 130° C., and then kept constant for 30 minutes. Then the temperature is still kept at 130°C, and the mixed solution containing 21810 styrene and 14g 2,2'-azobisisobutyronitrile is continuously added within 1 hour, and then the temperature is lowered to 110°C after the feeding is completed, and the constant temperature reaction After 4 hours, the unreacted maleic anhydride was washed away with acetone, and the unreacted styrene was removed in a vacuum oven at 80°C to obtain a block-shaped styrene-maleic anhydride copolymer. The styrene-maleic anhydride copolymer contained 73.2 wt % of styrene monomer units and 26.8 wt % of maleic anhydride monomer units. Using GPC and using polystyrene as a standard, the number average molecular weight (Mn) was 37260, the weight average molecular weight (Mw) was 65228, and PDI=1.75.

Aromatic compounds with phosphite groups: bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite.

Heat stabilizer: In formula (3), R ₅ is methyl, R ₆ and R ₇ are both tertiary pentyl, R ₈ is hydrogen.

Antioxidant: 3,9-bis(2-(3-(3-tertiary-butyl-4-hydroxy-5-methylphenyl)propionyloxy)-1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro(5,5)undecane.

UV absorber: 2,2'-methylenebis[6-(benzotriazol-2-yl)-4-tert-octylphenol, flash point is 420.5±35.7℃.

[evaluation item]

Transmittance (T%): After making the polymethacrylate composition of Examples 1 to 4 and Comparative Example 1 into a disk test piece with a diameter of 5.5 cm and a thickness of 3 mm, a haze meter (Haze Meter NDH 2000N) to measure it, unit: %. According to the requirements of commercially available optical components, it is generally expected to have a transmittance greater than 90%.

Haze (HAZE): After making the polymethacrylate composition of Examples 1 to 4 and Comparative Example 1 into a disc test piece with a diameter of 5.5 cm and a thickness of 3 mm, a haze meter (Haze Meter NDH 2000N) Measure it, unit: %. According to the requirements of commercially available optical components, it is generally expected to have a haze of less than 1.5.

Yellowness (yellow index, YI value): After the polymethacrylate compositions of Examples 1 to 4 and Comparative Example 1 were made into disc test pieces with a diameter of 5.5 cm and a thickness of 3 mm, the computer spectroscopic formula of Nippon Denshoku Color difference meter SA-2000 measurement.

Glass transition temperature (Glass transition temperature, Tg): The polymethacrylate compositions of Examples 1 to 4 and Comparative Example 1 were measured with a differential scanning calorimeter (DSC). Unit: °C.

Thermal cracking temperature (5% thermogravimetric loss temperature, Td): get 5 milligrams of the polymethyl methacrylate resin composition of embodiment 1 to 4 and comparative example 1 as sample, place thermogravimetric analyzer (Thermal Gravimetric Analysis, referred to as TGA), the analysis conditions are as follows: in the nitrogen environment, the temperature is raised from 100°C to 600°C at a heating rate of 20°C/min, and the temperature at 5% weight loss is measured.

Example 1 to 4

Embodiments 1 to 2 are to mix methacrylate polymer 1 with styrene-maleic anhydride copolymer 1 according to the ratio listed in Table 1, wherein methacrylate polymer 1 and styrene- Maleic anhydride-based copolymer 1 is 100 parts by weight in total; Embodiment 3 is to mix methacrylate-based polymer 1 with styrene-maleic anhydride-based copolymer 2 according to the ratio listed in Table 1, wherein methyl Acrylate polymer 1 and styrene-maleic anhydride copolymer 2 add up to 100 parts by weight; embodiment 4 is that methacrylate polymer 2 and styrene-maleic anhydride copolymer 3 are based on The ratio listed in Table 1 was mixed, wherein the total of methacrylate polymer 2 and styrene-maleic anhydride copolymer 4 was 100 parts by weight. Then add an aromatic compound with phosphite group, a heat stabilizer, an antioxidant and an ultraviolet absorber, mix and extrude the polymethacrylate composition by an extruder at 240° C. and granulate. The content values of aromatic compounds with phosphite groups, heat stabilizers, antioxidants and ultraviolet absorbers listed in Table 2 are the polymethacrylate compositions of Examples 1 to 4 in a high-efficiency liquid phase The actual content value measured after chromatography (HPLC) analysis. The detection results of the haze (HAZE), yellowness (YI), light transmittance (T%), glass transition temperature (Tg), and thermal cracking temperature (Td) of the polymethacrylate composition of Examples 1 to 4 It is also described in Table 2.

comparative example 1

Comparative example 1 is that methacrylate polymer 1 is mixed with styrene-maleic anhydride copolymer 1 according to the ratio listed in Table 1, wherein methacrylate polymer 1 and styrene-maleic anhydride The acid anhydride-based copolymer 1 is 100 parts by weight in total, and a polymethacrylate composition is prepared in the same manner as in Examples 1-2. The content values of heat stabilizer, antioxidant and ultraviolet absorber listed in Table 2 are the actual content measured after analyzing the polymethacrylate composition of Comparative Example 1 with high performance liquid chromatography (HPLC) Numerical values The test results of haze (HAZE), yellowness (YI), light transmittance (T%), glass transition temperature (Tg) and thermal cracking temperature (Td) are also recorded in Table 2.

Table 1

Table 2

It can be obtained from Table 2 that, compared with Comparative Example 1, Examples 1 to 4 containing 200ppm to 900ppm of aromatic compounds with phosphite groups can have comparative Good thermal stability (higher Td), which means that the composition can have both high pyrolysis temperature and high heat resistance. In addition, Examples 1-4 containing 200ppm to 900ppm of aromatic compounds with phosphite groups and 10000ppm to 50000ppm of UV absorbers also have better yellowness (YI) performance than Comparative Example 1.

In addition, it can also be seen from Table 2 that in addition to containing 200ppm to 900ppm of aromatic compounds with phosphite groups in Examples 1 to 4, they can maintain better heat resistance (higher Tg) and better heat resistance. In addition to the stability (higher Td), because it also contains 500ppm to 2000ppm of antioxidants, it has better haze performance than Comparative Example 1 under the action of aromatic compounds with phosphite groups and antioxidants. , the penetration is also higher.

Although the present invention has been disclosed above with the embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field may make some changes and modifications without departing from the spirit and scope of the present invention. The scope of protection of the present invention should be defined by the scope of the appended patent application.

10, 10': optical board 12: Ontology 122, 124: surface 126: side surface 132: The first microstructure 134:Second Microstructure

FIG. 1A is a schematic cross-sectional view of an optical element according to an embodiment of the present invention. FIG. 1B is a schematic cross-sectional view of an optical element according to another embodiment of the present invention. 2A to 2E are schematic diagrams of display devices according to various embodiments of the present invention.

10: Optical board

12: Ontology

122: surface

132: The first microstructure

Claims (13)

A polymethacrylate composition, comprising: 50 to 85 parts by weight of a methacrylate polymer, including a methacrylate monomer unit and an acrylate monomer unit, and its weight average molecular weight (Mw) is 20,000 to 200,000; 15 to 50 parts by weight of styrene-maleic anhydride copolymers, including: 65wt%~85wt% styrene monomer units, 15wt%~35wt% maleic anhydride monomers unit and 0~20wt% of the second copolymerizable monomer unit; aromatic compound with phosphite group; and 10000ppm to 50000ppm of ultraviolet absorber, the flash point of the ultraviolet absorber ≧240 ℃, wherein The ratio of the content of the ultraviolet absorber to the aromatic compound with phosphite groups ranges from 10 to 300, wherein the methacrylate polymer is copolymerized with the styrene-maleic anhydride The total amount of the compound is 100 parts by weight, and the content of the aromatic compound with phosphite group in the polymethacrylate composition is 200 ppm to 900 ppm. The polymethacrylate composition as described in item 1 of the scope of the patent application, wherein the methacrylate polymer includes: 92wt%~99wt% of the methacrylate monomer unit, 1wt%~ 8wt% of the acrylate monomer unit and 0-7wt% of the first copolymerizable monomer unit, and the weight average molecular weight (Mw) of the methacrylate polymer is 50,000-150,000. The polymethacrylate composition as described in item 1 of the scope of the patent application, wherein the styrene-based monomer unit of the styrene-maleic anhydride copolymer The ratio of the weight percentage to the weight percentage of the maleic anhydride monomer unit is 1-8.5. The polymethacrylate composition as described in item 1 of the scope of the patent application, wherein the weight average molecular weight (Mw) of the styrene-maleic anhydride copolymer is 60,000 to 100,000. The polymethacrylate composition as described in item 1 of the scope of the patent application, wherein the molecular weight distribution index (PDI) of the styrene-maleic anhydride copolymer is in the range of 1.5 to 2.05. The polymethacrylate composition described in item 1 of the scope of the patent application further includes an antioxidant, wherein the ratio of the content of the antioxidant to the aromatic compound with phosphite groups ranges from 1.1 to 10. The polymethacrylate composition as described in item 1 of the scope of the patent application further includes 500ppm to 2000ppm of antioxidant. The polymethacrylate composition as described in Item 1 of the scope of the patent application further includes 500ppm to 2000ppm of heat stabilizer. The polymethacrylate composition described in item 1 of the scope of the patent application, wherein the ratio of the content of the ultraviolet absorber to the aromatic compound with phosphite groups ranges from 15 to 200. The polymethacrylate composition as described in item 1 of the scope of the patent application, wherein the ultraviolet absorber is selected from 2-(4,6-bis-(2,4-dimethylphenyl)-1,3 ,5-triazin-2-yl)-5-octyloxyphenol, 2,2'-methylenebis[6-(benzotriazol-2-yl)-4-tert-octylphenol], 2 -(4,6-Diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol, 2,2',4,4'-tetrahydroxydiphenyl Ketone, 3-[(2-cyano-3,3-diphenylacryl)oxy]-2,2-bis{[(2-cyano-3,3-diphenylacryl)oxy] Methyl}propyl 2-cyano -3,3-diphenylacrylate, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol, 2-(2'-hydroxy-3',5 At least one of the group consisting of '-dipentylphenyl) benzotriazole. An optical element is formed of the polymethacrylate composition described in any one of the first to tenth items of the patent application. The optical element as described in claim 11 of the patent application, wherein the optical element is at least one selected from the group consisting of an optical plate, an optical sheet, and an optical film. A display device, comprising: the optical element as described in item 11 of the scope of the patent application, wherein the display device is selected from a television, a digital camera, a digital video camera, a digital photo frame, a mobile phone, a notebook personal computer, a mobile computer, At least one of the group consisting of a monitor for a computer, a portable game machine, a portable information terminal, an audio reproduction device, a game machine, and a display for a car.

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