Patent Description:
The present invention relates to a polycarbonate resin composition having excellent transparency and color stability, and low ultraviolet transmittance, and an optical molded article composed thereof.

Polycarbonate resins are prepared by condensation-polymerization of an aromatic diol such as bisphenol A with a carbonate precursor such as phosgene, and have excellent impact strength, dimensional stability, heat resistance, transparency, etc. Thus, the polycarbonate resins have applicability for a wide range of uses, such as exterior materials of electrical and electronic products, automobile parts, building materials, optical components, etc..

On the other hand, optical lenses used in eyeglasses or sunglasses are required to have transmittance to such an extent that no glare from exterior light sources occurs while not affecting the visual field. Further, it is necessary to protect the eyes from harmful rays of a specific wavelength such as UV. To apply polycarbonate resins having excellent optical properties as well as mechanical properties to optical lenses for outdoor activities such as eyeglasses or sunglasses, a variety of technologies have been developed.

However, polycarbonate resins exhibit low transmittance in a range of about <NUM> or less in the ultraviolet region, but there is a problem in that the transmittance increases in a region above <NUM>. To improve this problem, various additives are used together to control the physical properties of the polycarbonate resins. However, there is a problem in that when any one of physical properties thereof is improved, other physical properties generally deteriorate.

<CIT> discloses a technique to increase a visible light-shielding property by using the polycarbonate resin in combination with a dye and a pigment, but the technique does not simultaneously realize physical properties such as a proper shielding property in the ultraviolet region and transparency. <CIT> relates to crates made out of a transparent or translucent material absorbing UV radiation and part of the visible light. The crate is made out of a thermoplastic material (polycarbonate, Mw <NUM>-<NUM>/mol) further comprising a dye and/or UV absorbers.

The present invention provides a polycarbonate resin composition having excellent transparency and color stability, and low ultraviolet transmittance.

Further, the present invention provides an optical molded article including the polycarbonate resin composition.

To solve the above problem, the present invention provides a polycarbonate resin composition including a polycarbonate resin, a black colorant, a yellow colorant, and at least one ultraviolet absorber selected from the group consisting of a benzotriazole-based compound, a benzophenone-based compound, and a triazine-based compound, each including at least one hydroxyl group, wherein the yellow colorant is included in an amount of <NUM> ppmw to <NUM> ppmw with respect to the total dry weight of the composition, and wherein an average transmittance in a wavelength region of <NUM> to <NUM> is <NUM> % to <NUM> %, as measured in accordance with ASTM D1003.

The polycarbonate resin is a resin prepared by condensation-polymerization of an aromatic diol such as bisphenol A with a carbonate precursor such as phosgene. The polycarbonate resin in itself has excellent mechanical and optical properties, but is required to satisfy many physical properties at the same time according to its application fields. When the polycarbonate resin is used in articles such as lenses for outdoor activities, it is necessary to reduce the transmittance in the ultraviolet region. To improve this, various techniques have been developed, but there has been a problem in that when any one of physical properties thereof is improved, other physical properties generally deteriorate.

Accordingly, in order to realize low ultraviolet transmittance and excellent transparency and color stability at the same time, the present inventors developed a polycarbonate resin composition using an additive having high light absorption in a specific wavelength region and a combination of specific colorants.

The polycarbonate resin composition according to the present invention includes a specific ultraviolet absorber and a specific combination of colorants to satisfy an average transmittance of <NUM> % to <NUM> % in a wavelength region of <NUM> to <NUM>, as measured in accordance with ASTM D1003. The resin composition meeting the above range may exhibit low ultraviolet transmittance and excellent transparency and color stability at the same time. The average transmittance of the above range may preferably be <NUM> % to <NUM> %. When meeting the above range, the resin composition may become excellent in the above-described physical properties, and therefore, it may be easily applied to optical molded articles, particularly lenses for eyeglasses, sunglasses, etc..

In the present invention, the average transmittance is measured in accordance with ASTM D1003, and is obtained by calculating an average value (T380-<NUM>) of transmittances which are measured from <NUM> to <NUM> at <NUM> wavelength intervals. In detail, the polycarbonate resin composition of the present invention is prepared as pellets with a twin-screw extruder (L/D=<NUM>, Φ=<NUM>, barrel temperature <NUM>) at a rate of <NUM> per hour, and the pellets are injection-molded without residence time at a cylinder temperature of about <NUM> using an injection molding machine to prepare a specimen (width/length/thickness = <NUM>/<NUM>/<NUM>), and transmittance was measured in accordance with ASTM D1003 using UltraScan PRO equipment (manufactured by HunterLab).

The polycarbonate resin composition according to the present invention includes at least one ultraviolet absorber selected from the group consisting of a benzotriazole-based compound, a benzophenone-based compound, and a triazine-based compound, each including at least one hydroxyl group. These ultraviolet absorbers may be used together with a specific combination of colorants described below, thereby realizing low ultraviolet transmittance and excellent transparency and color stability at the same time.

Specifically, the ultraviolet absorber is a compound having high light absorption in the UV region of longer than about <NUM>, particularly, at about <NUM>, and may be used together with a specific combination of colorants, thereby improving UV absorption of the polycarbonate resin composition in the corresponding region.

The benzotriazole-based compound includes at least one hydroxyl group in the molecule, and specifically, it may be a compound represented by the following Chemical Formula <NUM>:
<CHM>.

The benzophenone-based compound includes at least one hydroxyl group in the molecule, and specifically, it may be a compound represented by the following Chemical Formula <NUM>:
<CHM>.

The triazine-based compound includes at least one hydroxyl group in the molecule, and specifically, it may be a compound represented by the following Chemical Formula <NUM>:
<CHM>
<CHM>.

In the present invention, the ultraviolet absorber may be included in an amount of <NUM> ppmw to <NUM>,<NUM> ppmw, preferably <NUM> ppmw to <NUM>,<NUM> ppmw, or <NUM> ppmw to <NUM> ppmw with respect to the total dry weight of the composition. The ultraviolet absorber may be included in the above range of the content and used in combination with colorants described below, thereby realizing the desired effects of the present invention.

The polycarbonate resin composition according to the present invention includes a black colorant and a yellow colorant at the same time, which are used together with the above-described specific ultraviolet absorber, thereby realizing low ultraviolet transmittance and excellent transparency and color stability at the same time.

In particular, when the black colorant and the yellow colorant are used in combination, it is possible to solve a problem of color stability deterioration which may be generated when the yellow colorant is used alone. Further, due to the synergistic effect thereof, it is possible to realize low light transmittance in the UV region, particularly at <NUM>, and excellent color stability at the same time.

The black colorant may be at least one selected from the group consisting of an anthraquinone-based compound, an azophenyl-based compound, an acetamide-based compound, and a carbon-based compound, and preferably, an anthraquinone-based compound or a carbon-based compound.

A commercially available black colorant may include Nigrosine Black G of BASF, Nigrosin BASE BA of Bayer, Nubian Black PC-<NUM> of Orient Chemical, ABCOL Nigrosine Z1630 of Abbey Color, etc..

In the present invention, the black colorant may be included in an amount of <NUM> ppmw to <NUM> ppmw, preferably <NUM> ppmw to <NUM> ppmw, or <NUM> ppmw to <NUM> ppmw with respect to the total dry weight of the composition. The black colorant may be included in the above range of the content and used in combination with the ultraviolet absorber of the present invention, thereby realizing the desired effects of the present invention.

The yellow colorant may be at least one selected from the group consisting of a quinoline-based compound, a pyrazole-based compound, and a naphthalene-based compound, and preferably, a quinoline-based compound or a pyrazole-based compound.

A commercially available yellow colorant may include Macrolex Yellow G of Bayer, Sandoplast Yellow <NUM> of Clariant, Transparent Yellow <NUM> of Yabang, Kenawax Yellow BGP of Albion Colours, Solvent Yellow <NUM> (<NPL>), etc..

In the present invention, the yellow colorant is included in an amount of <NUM> ppmw to <NUM> ppmw, preferably <NUM> ppmw to <NUM> ppmw, or <NUM> ppmw to <NUM> ppmw with respect to the total dry weight of the composition. The yellow colorant may be included in the above range of the content and used in combination with the ultraviolet absorber of the present invention, thereby realizing the desired effects of the present invention.

In the present invention, a mixing ratio of the yellow colorant and the black colorant is controlled, thereby efficiently improving optical properties of the polycarbonate resin composition. The mixing ratio of the yellow colorant and the black colorant may be <NUM>:<NUM> to <NUM>:<NUM>. The mixing ratio may be preferably <NUM>:<NUM> to <NUM>:<NUM>, and more preferably <NUM>:<NUM> to <NUM>:<NUM>.

The polycarbonate resin according to the present invention is a resin prepared by condensation-polymerization of an aromatic diol such as bisphenol A with a carbonate precursor such as phosgene, and preferably, the polycarbonate resin includes a repeating unit represented by the following Chemical Formula <NUM>:
<CHM>.

Preferably, R'<NUM> to R'<NUM> are each independently hydrogen, methyl, chloro, or bromo.

Further, Z' is preferably a linear or branched C<NUM>-<NUM> alkylene unsubstituted or substituted with a phenyl, and more preferably, methylene, ethane-<NUM>,<NUM>-diyl, propane-<NUM>,<NUM>-diyl, butane-<NUM>,<NUM>-diyl, <NUM>-phenylethane-<NUM>,<NUM>-diyl, or diphenylmethylene. Further, Z is preferably cyclohexane-<NUM>,<NUM>-diyl, O, S, SO, SO<NUM>, or CO.

The repeating unit represented by Chemical Formula <NUM> is formed by reaction of an aromatic diol compound with a carbonate precursor.

Preferably, the repeating unit represented by Chemical Formula <NUM> may be derived from any one or more aromatic diol compounds selected from the group consisting of bis(<NUM>-hydroxyphenyl)methane, bis(<NUM>-hydroxyphenyl)ether, bis(<NUM>-hydroxyphenyl)sulfone, bis(<NUM>-hydroxyphenyl)sulfoxide, bis(<NUM>-hydroxyphenyl)sulfide, bis(<NUM>-hydroxyphenyl)ketone, <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)ethane, bisphenol A, <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)butane, <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)cyclohexane, <NUM>,<NUM>-bis(<NUM>-hydroxy-<NUM>,<NUM>-dibromophenyl)propane, <NUM>,<NUM>-bis(<NUM>-hydroxy-<NUM>,<NUM>-dichlorophenyl)propane, <NUM>,<NUM>-bis(<NUM>-hydroxy-<NUM>-bromophenyl)propane, <NUM>,<NUM>-bis(<NUM>-hydroxy-<NUM>-chlorophenyl)propane, <NUM>,<NUM>-bis(<NUM>-hydroxy-<NUM>-methylphenyl)propane, <NUM>,<NUM>-bis(<NUM>-hydroxy-<NUM>,<NUM>-dimethylphenyl)propane, <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)-<NUM>-phenylethane, bis(<NUM>-hydroxyphenyl)diphenylmethane, and α,ω-bis[<NUM>-(o-hydroxyphenyl)propyl]polydimethylsiloxane.

The phrase 'derived from an aromatic diol compound' means that the repeating unit represented by Chemical Formula <NUM> is formed by reaction of a hydroxyl group of the aromatic diol compound and a carbonate precursor.

For example, when bisphenol A as the aromatic diol compound is polymerized with triphosgene as the carbonate precursor, the first repeating unit is represented by the following Chemical Formula <NUM>-<NUM>:
<CHM>.

The carbonate precursor may be one or more selected from the group consisting of dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl)carbonate, di-m-cresyl carbonate, dinaphthyl carbonate, bis(diphenyl) carbonate, phosgene, triphosgene, diphosgene, bromo phosgene, and bishaloformate. Preferably, triphosgene or phosgene may be used.

The polycarbonate resin according to the present invention may have a weight average molecular weight of <NUM>/mol to <NUM>,<NUM>/mol, and preferably <NUM>,<NUM>/mol to <NUM>,<NUM>/mol.

More preferably, the weight average molecular weight may be <NUM>,<NUM>/mol or more, <NUM>,<NUM>/mol or more, <NUM>,<NUM>/mol or more, <NUM>,<NUM>/mol or more, <NUM>,<NUM>/mol or more, <NUM>,<NUM>/mol or more, <NUM>,<NUM>/mol or more, <NUM>,<NUM>/mol or more, or <NUM>,<NUM>/mol or more. Further, the weight average molecular weight may be <NUM>,<NUM>/mol or less, <NUM>,<NUM>/mol or less, or <NUM>,<NUM>/mol or less.

The polycarbonate resin composition according to the present invention may include the above-described polycarbonate resin, black colorant, yellow colorant, and ultraviolet absorber, and may realize excellent transparency and color stability and low ultraviolet transmittance due to the synergistic effect of the combination of the components. In particular, by meeting the average transmittance value in the above-described specific wavelength region, the polycarbonate resin composition may preferably realize excellent physical properties when applied to desired products (particularly, optical molded articles).

The resin composition according to the present invention may further include one or more additives selected from the group consisting of an antioxidant, a heat stabilizer, a plasticizer, an antistatic agent, a nucleating agent, a flame retardant, a lubricant, an impact modifier, a fluorescent brightener, and a radiosorbent, which are commonly used in the art, as needed.

The resin composition according to the present invention may be prepared by mixing a polycarbonate, a cyclic phosphite ester compound, a linear phosphite ester compound, a vinyl-based polymer containing (meth)acrylate repeating units containing an epoxy functional group, and a photoreactive compound containing a phenylene functional group, and optionally, an additive. As described below, the resin composition is preferably prepared as pellets by melt-kneading in order to produce an optical molded article.

The melt-kneading may be performed by methods commonly used in the art, for example, methods using a ribbon blender, a Henschel mixer, a Banbury mixer, a drum tumbler, a single screw extruder, a twin screw extruder, a co-kneader, a multi-screw extruder, etc. The temperature of the melt-kneading may be adjusted appropriately as needed, and for example, the temperature may be adjusted to <NUM> to <NUM>.

Further, the present invention provides an optical molded article including the resin composition. Preferably, the optical molded article may be an optical lens requiring ultraviolet protection, such as a lens for eyeglasses, a lens for sunglasses, etc. The resin composition according to the present invention may have excellent transparency and color stability, and low ultraviolet transmittance, thereby being usefully applied to optical molded articles.

A method of producing the molded article may be a method that is commonly used in the art. For example, a melt-kneaded mixture or pellet of the resin composition according to the present invention as a raw material may be applied to molding methods such as an injection molding method, an injection compression molding method, an extrusion molding method, a vacuum molding method, a blow molding method, a press molding method, a pressure forming method, a foam molding method, a thermal bending molding method, a compression molding method, a calender molding method, a rotational molding method, etc..

The size or thickness of the molded article may be appropriately adjusted in accordance with the purpose of use, and the molded article may have a flat plate or curved shape in accordance with the purpose of use.

As descried above, a polycarbonate resin composition according to the present invention has excellent transparency and color stability, and low ultraviolet transmittance, by using an additive having high light absorption in a specific wavelength region and a combination of specific colorants.

<FIG> is an image showing appearance evaluation criteria of examples and comparative examples.

Hereinafter, preferred embodiments will be provided for better understanding of the present invention. However, the following embodiments are for illustrative purposes only, and the present invention is not intended to be limited thereby.

The following materials were used in the examples and comparative examples.

The respective components were mixed in a content as described in Table <NUM> below, and pellets were produced at a rate of <NUM> per hour with a twin-screw extruder (LID = <NUM>, Φ = <NUM>, barrel temperature: <NUM>).

In Table <NUM>, the content of the polycarbonate resin (A) refers to an amount excluding the contents of the remaining colorant (B) and ultraviolet absorber (C) from a total of <NUM> wt% of the composition.

The respective resin pellets prepared in the examples and comparative examples were injection-molded without residence time at a cylinder temperature of <NUM> using an injection molding machine N-20C (manufactured by JSW, Ltd. ) to prepare a specimen (width/length/thickness = <NUM>/ <NUM>/ <NUM>), while transmittance (T) was measured using UltraScan PRO equipment (manufactured by HunterLab) (instrument setting: <NUM> to <NUM>) in accordance with ASTM D1003, and the results are shown in the following Table <NUM>.

Further, transmittance (T<NUM>) at <NUM> was measured, and transmittances from <NUM> to <NUM> were also measured at <NUM> wavelength intervals, and an average value thereof (T<NUM>-<NUM>) is shown in the following Table <NUM>.

The color stability was evaluated by combining the following evaluation results of yellowness index and appearance. Higher YI values negatively influence deterioration of color stability, but resins with a YI value of up to about <NUM> may be applied to products. However, even if the YI value is <NUM> or less, color stability is considered to be lowered, when a yellow color is observed with the naked eye.

The respective resin pellets prepared in the examples and comparative examples were injection-molded without residence time at a cylinder temperature of <NUM> using an injection molding machine N-20C (manufactured by JSW, Ltd. ) to prepare a specimen (width/length/thickness = <NUM>/ <NUM>/ <NUM>), while YI values were measured using UltraScan PRO equipment (manufactured by HunterLab) in accordance with ASTM D1925, and the results are shown in the following Table <NUM>.

The respective resin pellets prepared in the examples and comparative examples were injection-molded without residence time at a cylinder temperature of <NUM> using an injection molding machine N-20C (manufactured by JSW, Ltd. ) to prepare a specimen (width/length/thickness = <NUM>/ <NUM>/ <NUM>), and yellowness of the specimen was observed with the naked eye. ∘, △, and X were determined by relative evaluation between the subject specimens.

As shown in Table <NUM>, examples of the present invention were confirmed to have excellent transparency and low UV transmittance at <NUM> at the same time by using the additive having high light absorption in a specific wavelength region and a combination of the specific colorants. Further, when the samples were observed with the naked eye, they showed almost no yellow color, and their YI values were <NUM> or less, indicating excellent color stability.

Comparative examples not using the ultraviolet absorber and colorants showed very high <NUM>-<NUM> average transmittance, and most of the samples showed a dark yellow color. In particular, it was confirmed that Comparative Examples <NUM> to <NUM> using different materials which are conventionally used as ultraviolet absorbers showed overall excellent average transmittance, but remarkably high transmittance at <NUM>, as compared with the examples.

Claim 1:
A polycarbonate resin composition comprising a polycarbonate resin, a black colorant, a yellow colorant, and at least one ultraviolet absorber selected from the group consisting of a benzotriazole-based compound, a benzophenone-based compound, and a triazine-based compound,
wherein the yellow colorant is included in an amount of <NUM> ppmw to <NUM> ppmw with respect to the total dry weight of the composition, and
wherein an average transmittance in a wavelength region of <NUM> to <NUM> is <NUM> % to <NUM> %, as measured in accordance with ASTM D1003.