JP5457617B2 - Styrenic resin composition and molded body - Google Patents

Description

  The present invention relates to a styrenic resin composition and a molded body using the same.

  A screen lens such as a transmission screen used for a projection television projects an image on the screen and displays the image. Since this screen lens is desired to be bright and have a wide viewing angle for the observer, it is generally configured to be combined with a lens molding such as a lenticular lens or a Fresnel lens. For these lens molded bodies, methacrylic resins having excellent transparency, light resistance, scratch resistance, molding processability, etc. are widely used. These molded bodies are generally press molded, extruded, cast molded, injection molded. Molded by molding or the like.

  Since the methacrylic resin used for such a screen lens has a high water absorption rate, a molded body made of the methacrylic resin is likely to change in dimensions due to water absorption. In order to solve the problem, a resin obtained by dissolving a styrene-diene copolymer in a mixture of an aromatic vinyl monomer, a (meth) acrylic acid ester monomer, and a polyfunctional unsaturated monomer. A method for obtaining a Fresnel lens by using a lens is disclosed (see Patent Document 1).

  Further, the same problem has also been encountered with liquid crystal TV diffusion plates, lighting covers, lighting signs, optical display devices, and the like using methacrylic resin.

Japanese Patent Laid-Open No. 5-341101

  It is an object of the present invention to provide a styrenic resin composition with improved light resistance and a molded body of the resin composition.

  As a result of intensive studies to solve the above problems, the present inventors have found that a copolymer mainly composed of a styrene monomer unit and a methacrylic acid monomer unit, a specific unmelted compound, a specific light-proofing agent, and The present invention has found that a molded article having excellent light transmittance, dimensional stability, light resistance, and light diffusibility can be obtained by injection molding or extrusion molding a styrene resin composition containing a specific colorant. Has reached

That is, the present invention includes a styrene copolymer comprising a styrene monomer unit and a (meth) acrylic acid ester monomer unit, an unmelted compound, a hindered amine compound, and a benzotriazole compound. The styrene resin composition further includes 0.005 to 0.5 parts by mass of a europium compound in the styrene resin composition, and the europium compound is represented by the following structural formulas (A) to (C). Or a mixture thereof, a styrene resin composition.
(A) Y (PV) O; Eu ³⁺ , (B) (BaMg) Al ₁₁ O _18.5 Eu ³⁺ , (C) (BaMg) Al ₈ O ₁₀ Eu ²⁺
Further, the present invention is an injection molded body or an extruded molded body having a thickness of 1 to 7 mm made of the styrenic resin composition.

  The molded body made of the styrenic resin composition obtained in the present invention is excellent in light resistance, optical characteristics such as light transmittance and light diffusibility, and dimensional stability.

Hereinafter, the present invention will be described in detail.
Examples of the styrenic monomer used in the present invention include styrene, α-methylstyrene, p-methylstyrene, pt-butylstyrene, and the like, and styrene is preferable.

  Examples of the (meth) acrylic acid ester monomer in the present invention include methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-methylhexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, and the like. Is mentioned. These may be used alone or in combination of two or more. Preferably, it is methyl methacrylate, ethyl acrylate, n-butyl acrylate or a mixture thereof.

The styrene copolymer is preferably composed of 30 to 100% by mass of a styrene monomer unit and 70 to 0% by mass of a (meth) acrylic acid ester monomer unit. If the styrene monomer unit is less than 30% by mass, the molded product may be deformed by moisture absorption.

In addition to the above styrene monomer and (meth) acrylic acid ester monomer, the styrene copolymer may contain a vinyl monomer copolymerizable therewith, and the amount thereof is a styrene monomer. 10 mass parts or less are preferable with respect to 100 mass parts of total amounts of a monomer and a (meth) acrylic acid ester monomer. Examples of the copolymerizable vinyl monomer include vinyl cyanide monomers such as acrylonitrile and methacrylonitrile, methacrylic acid, acrylic acid, maleic anhydride, maleic acid, itaconic acid, itaconic anhydride, and the like. Examples thereof include unsaturated carboxylic acid monomers, maleimide monomers such as maleimide, N-methylmaleimide, and N-phenylmaleimide. These may be used alone or in combination of two or more.

The unmelted compound is preferably a compound having a melting point or softening point at 200 ° C. or higher under an atmosphere of 1 atm. When the melting point and softening point are less than 200 ° C., the compound is easily melted at the time of melt-kneading with a styrene-based polymer or at the time of extrusion molding / injection molding of a styrene-based resin composition, and cannot retain excellent optical properties. There is a case. The unmelted compound preferably has a refractive index difference from the styrene copolymer of 0.05 to 0.15 and an average particle diameter of 2 to 10 μm. If the difference in refractive index is less than 0.05, the haze and diffusivity become small and the light diffusibility decreases, and if it exceeds 0.15, the total light transmittance and the light diffusivity may decrease. Further, when the average particle size is less than 2 μm, the haze and diffusivity become small and the light diffusibility decreases, and when it exceeds 10 μm, the total light transmittance and the light diffusivity may decrease. The average particle size of the unmelted compound is a value obtained by measurement using a Coulter Multisizer (manufactured by Beckman Coulter, Inc.).
Moreover, although there is no restriction | limiting in particular in the compounding quantity of an unmelted compound, It is preferable to contain 1-10 mass parts with respect to 100 mass parts of styrene-type copolymers. When the content of the unmelted compound is less than 1 part by mass, the haze and diffusivity become small and the light diffusibility decreases, and when it exceeds 10 parts by mass, the total light transmittance and the light diffusivity may decrease. Although it does not specifically limit as an unmelted compound, The crosslinked copolymer containing methyl methacrylate as a monomer and the crosslinked copolymer containing methyl methacrylate and n-butyl acrylate as a monomer are preferable.

Although there is no restriction | limiting in particular in the compounding quantity of the hindered amine type compound and benzotriazole type compound which are mix | blended with the styrene resin composition of this invention, 0.1-2 mass of hindered amine compounds with respect to 100 mass parts of styrene copolymers. It is preferable to contain 0.1-2 mass parts of benzotriazole type compounds.
When the amount of the hindered amine compound or the benzotriazole compound is less than 0.1 parts by mass, the light resistance may not be sufficient. When the amount exceeds 2 parts by mass, the yellowness of the obtained light diffusion sheet tends to increase.
The hindered amine compound is an amine-based light stability improver, for example, decanoic acid bis (2,2,6,6-tetramethyl-1 (octyloxy) -4-piperidinyl) ester, 1,1- Dimethylethyl hydroperoxide, bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate Bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate, bis (2,2,6,6- Tetramethyl-4-piperidyl) sebacate and the like, and these may be used alone or in combination of two or more.
The benzotriazole-based compound is an ultraviolet absorber, for example, 2- (2H-benzotriazol-2-yl) -p-cresol, 2- (2H-benzotriazol-2-yl) -4-6. -Bis (1-methyl-1-phenylethyl) phenol, 2- [5-chloro (2H) -benzotriazol-2-yl] -4-methyl] -6- (t-butyl) phenol, 2,4- Di-t-butyl-6- (5-chlorobenzotriazol-2-yl) phenol, 2- (2H-benzotriazol-2-yl) -4,6-di-t-pentylphenol, 2- (2H- Benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol and the like may be used, and these may be used alone or in combination of two or more.

The styrene-based resin composition needs to contain 0.005 to 0.5 parts by mass of a europium compound that is a fluorescent pigment with respect to 100 parts by mass of the styrene-based copolymer. If the europium compound is less than 0.005 parts by mass, the yellowness is strong and the appearance defect is not improved. Moreover, there exists a tendency for the value of the total light transmittance of the molded object obtained as a result to fall. When it exceeds 0.5 mass part, the total light transmittance of the resin composition obtained will fall. Further, a fluorescent brightener added for the purpose of suppressing the yellowness of the resin whose yellowness has been increased by an ultraviolet absorber or the like, for example, 2,5-thiophenediyl (5-t-butyl-1,3-benzoxazole) Compared with the case of using this europium compound, the use of this europium compound is also characterized in that the heat resistance of the styrene-based resin composition is less deteriorated.
The europium compound is not particularly limited as long as it is a europium compound having fluorescent properties, but the following structural formulas (A) to (C) are preferable, and even if they are used alone, It may be used in a mixture.
(A) Y (PV) O; Eu ³⁺ , (B) (BaMg) Al ₁₁ O _18.5 Eu ³⁺ , (C) (BaMg) Al ₈ O ₁₀ Eu ²⁺

  Although there is no restriction | limiting in particular in the manufacturing method of the styrene-type copolymer of this invention, The block polymerization method, suspension polymerization method, solution polymerization method, and emulsion polymerization method can be employ | adopted suitably.

  In order to produce a styrene-based resin composition, there is no particular limitation on the method of blending the unmelted compound into the styrene-based copolymer. There is a method of blending with a copolymer.

Even when the styrene copolymer is pelletized and then melted and mixed with the unmelted compound, the mixing method is not particularly limited. For example, after premixing with a known mixing device such as a Henschel mixer or a tumbler mixer By performing melt-kneading using an extruder such as a single-screw extruder or a twin-screw extruder, a styrene resin composition can be produced by uniformly mixing. When melt-mixing an unmelted compound, a hindered amine compound or a benzotriazole compound can be blended at the same time.
Also, a high-concentration mixture in which unmelted compound, hindered amine-based compound, and benzotriazole-based compound are mixed at a high concentration with a styrene copolymer is prepared, and this high-concentration mixture and styrene-based copolymer are mixed during injection / extrusion molding. A material obtained by dry blending the coalesced so that the content of each component has a specified concentration may be used as a raw material.

  An additive can be mix | blended with the styrene resin composition of this invention as needed. For example, a plasticizer, a lubricant, silicone oil or the like can be blended in order to improve fluidity and releasability. Moreover, in order to improve thermal stability, a thermal stabilizer can be mix | blended. Furthermore, an antistatic agent can be blended in order to impart antistatic performance.

As for the thickness of the molded object in this invention, 1-7 mm is preferable. If it is less than 1 mm or exceeds 7 mm, excellent light diffusibility may not be obtained.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples.

Production of Styrene Copolymer (A) A first complete mixing tank with a volume of 5 L and a second complete mixing tank with a capacity of 15 L are connected in series, and further a first devolatilization tank and a second devolatilization tank with a preheater are provided. Two units were connected in series. 15 parts by mass of ethylbenzene, 0.01 parts by mass of t-butylperoxyisopropyl monocarbonate, 2,4-diphenyl-4-l with respect to 100 parts by mass of a monomer solution composed of 20% by mass of styrene and 80% by mass of methyl methacrylate. 0.2 parts by mass of methyl-1-pentene was mixed to obtain a raw material solution. This raw material solution was supplied to the first complete mixing tank controlled at 135 ° C. at 6.0 kg / hour. The conversion rate at the outlet of the first complete mixing tank was 28%. Next, it extracted continuously from the 1st complete mixing tank, and supplied to the 2nd complete mixing tank controlled to 135 degreeC. The conversion rate at the second complete mixing vessel outlet was 63%. Next, it extracted continuously from the 2nd complete mixing tank, heated with the preheater, and introduce | transduced into the 1st devolatilization tank controlled to 67 kPa and 160 degreeC. Furthermore, it extracted continuously from the 1st devolatilization tank, heated with the preheater, and introduce | transduced into the 2nd devolatilization tank controlled to 1.3 kPa and 230 degreeC, and the monomer was removed. This was extruded and cut into strands to obtain a pellet-shaped styrene copolymer (A-1).

A styrene copolymer (A-2) is obtained in the same manner as the styrene copolymer (A-1) except that a monomer solution composed of 55 mass% styrene and 45 mass% methyl methacrylate is used. It was.

The styrene copolymer (A-3) is obtained in the same manner as the styrene copolymer (A-1) except that a monomer solution composed of 80% by mass of styrene and 20% by mass of methyl methacrylate is used. It was.

Except having used the monomer solution comprised by 100 mass% of styrene, it implemented similarly to the styrene-type copolymer (A-1), and obtained the styrene-type copolymer (A-4).

Polyorganosiloxane cross-linked beads which are unmelted compounds (B)
As an unmelted compound, polyorganosiloxane cross-linked beads (average particle size 6 μm, refractive index 1.420, Toshiba Silicone Tospearl 2000B) were used.

Production of unmelted MMA-nBA copolymer crosslinked beads (C) 20 parts by mass of methyl methacrylate, 80 parts by mass of n-butyl acrylate, 5 parts by mass of divinylbenzene as a crosslinking agent, and polymerization initiator as an autoclave with a stirrer 0.2 parts by weight of benzoyl peroxide, 0.001 part by weight of sodium dodecylbenzenesulfonate and 0.5 parts by weight of tribasic calcium phosphate as suspension stabilizers, 200 parts by weight of pure water were charged at a temperature of 95 ° C. for 6 hours. Furthermore, polymerization was performed at a temperature of 130 ° C. for 2 hours. After completion of the reaction, washing, dehydration and drying were performed to obtain crosslinked beads (C). The average particle diameter of the crosslinked beads (C) was 4 μm, and the refractive index was 1.460.

Production of styrene-MMA cross-linked beads (D) as an unmelted compound In an autoclave equipped with a stirrer, 40 parts by mass of styrene, 60 parts by mass of methyl methacrylate, 5 parts by mass of divinylbenzene as a cross-linking agent, benzoyl peroxide 0. 2 parts by mass, as a suspension stabilizer, 0.001 part by mass of sodium dodecylbenzenesulfonate, 0.5 part by mass of tribasic calcium phosphate, and 200 parts by mass of pure water were charged, and the temperature was raised to 95 ° C. for 6 hours and further to 130 ° C. For 2 hours. After completion of the reaction, washing, dehydration and drying were performed to obtain crosslinked beads (D). The average particle diameter of the crosslinked beads was 8 μm, and the refractive index was 1.535.

Production of unmelted PMMA cross-linked beads (E) Autoclave with stirrer 100 parts by weight of methyl methacrylate, 5 parts by weight of divinylbenzene as cross-linking agent, 0.2 parts by weight of benzoyl peroxide as polymerization initiator, stable suspension As an agent, 0.001 part by mass of sodium dodecylbenzenesulfonate, 0.5 part by mass of tribasic calcium phosphate and 200 parts by mass of pure water were charged, and polymerization was performed at a temperature of 95 ° C. for 6 hours and further at a temperature of 130 ° C. for 2 hours. After completion of the reaction, washing, dehydration and drying were performed to obtain crosslinked beads (E-1). The average particle diameter of the crosslinked beads was 8 μm, and the refractive index was 1.494. A crosslinked bead (E-2) having an average particle diameter of 1 μm and a refractive index of 1.494 was obtained by the same production method as E-1, except that 1.5 parts by mass of tricalcium phosphate was used. Further, a crosslinked bead (E-3) having an average particle diameter of 3 μm and a refractive index of 1.494 was obtained by the same production method as E-1, except that 1.0 part by mass of tricalcium phosphate was used. Further, a crosslinked bead (E-4) having an average particle diameter of 13 μm and a refractive index of 1.494 was obtained by the same production method as E-1, except that 0.2 part by mass of tricalcium phosphate was used.

Colorant (F)
As colorants, fluorescent pigment Y (PV) O; Eu ³⁺ (UVR-1 manufactured by Dalian Road Light Source Co., Ltd.) (F-1), (BaMg) Al ₁₁ O _18.5 Eu ³⁺ (Dalian Road Light Source Co., Ltd.) UVG-1) (F-2), (BaMg) Al ₈ O ₁₀ Eu ²⁺ (UVB-1 manufactured by Dalian Road Light Source Co., Ltd.) (F-3), fluorescent brightener 2,5-thiophenediyl ( 5-t-butyl-1,3-benzoxazole) (Ubitex OB manufactured by Ciba Specialty Chemicals) (F-4) was used.

  Styrene copolymers (A-1) to (A-4), crosslinked beads B, C, D, (E-1) to (E-4), bis (2,2,6,6) as hindered amine compounds -Tetramethyl-4-piperidyl) sebacate, 2- (2H-benzotriazol-2-yl) -4,6-di-t-pentylphenol as benzotriazole-based compound and (F-1) to (F -4) was mixed at the compounding ratios shown in Tables 2-3, and kneaded and pelletized at a temperature of 240 ° C. and a screw rotation speed of 100 rpm using a 40 mm diameter single screw extruder. The pellets of styrene resin compositions 1 to 19 were obtained.

Examples 1-8 , Reference Examples 1-12 , Comparative Examples 1-3
Using styrene-based resin compositions 1 to 21, injection molding was performed at a cylinder temperature of 230 ° C. using a 9 ounce in-line screw injection molding machine (manufactured by Niigata Iron Works Co., Ltd.), dimensions 150 mm × 150 mm × 0.5 mm thickness, 150 mm × A molded body having a thickness of 150 mm × 2 mm and a thickness of 150 × 150 × 10 mm was obtained.
The obtained molded articles were evaluated for light resistance, optical characteristics, and dimensional stability (water absorption warpage), and are shown in Tables 4 to 7.
If the color difference ΔE is less than 0.5, it is judged that excellent light resistance is exhibited. When the haze is 99% or more, the total light transmittance is 67% or more, the diffusivity is 20% or more, and the b value is 0.5 or less, it can be said that the balance of optical characteristics is good, but this balance is not limited depending on the application. If the water absorption warpage is 1 mm or less, it is judged that the dimensional stability is excellent, but this may be larger depending on the application.

Example 9
Using the styrene-based resin composition 1, a sheet was prepared with a T-die type extruder. The extruder used was a 65 mmφ full flight screw single screw extruder. Each cylinder temperature in sheeting was operated and molded at 230 ° C. Table 6 shows data of optical properties, light resistance, and water absorption warpage of the obtained extruded sheet.

Each measuring method of the obtained molded body is as follows.
(1) Total light transmittance, haze: Measured according to ASTM D-1003 using a Nippon Denshoku Industries HAZE meter (NDH-2000).
(2) spreading factor: using Nippon Denshoku Industries Co., Ltd. goniophotometer (GC5000L), acceptance angle light transmittance _{I 0} of 0 °, measured receiving angle 70 ° light transmittance _{I 70,} the following equation Calculated.
Diffusion rate (%) = (I ₇₀ / I ₀ ) × 100
(3) b value: According to JIS Z 8722, hues L, a, and b were measured using a color difference meter (Σ-80) manufactured by Nippon Denshoku Industries Co., Ltd.
(4) Light resistance (color difference): Toyo Seiki Seisakusho Co., Ltd. Xenon Weatherometer, Atlas CI65A, the hue of the molded article before and after light irradiation after 400 Hr irradiation was manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS Z8722. Measurement was performed using a color difference meter (Σ-80). Also, the color difference ΔE was obtained by the following equation after measuring the hues L, a, and b, and this was used as a measure for evaluating light resistance.
ΔE = ((L−L ′) ² + (aa ′) ² + (b−b ′) ² ) ^1/2
However, L, a, b are hues before light irradiation, and L ′, a ′, b ′ are hues after light irradiation (after 400 Hr irradiation).
(5) Dimensional stability (water absorption warpage): A molded body cut to a size of 150 mm x 150 mm was left in an atmosphere of 50 ° C and 80% humidity for 7 days. After leaving in this state, the distance from the horizontal surface of the four corners of the molded body placed on the horizontal surface was measured with a caliper, the average value of the four points was determined as the value of water absorption warpage, and this value was used as a measure of dimensional stability. .

Evaluations other than the molded body were performed as follows.
(6) Refractive index: About an unmelted compound, it measured in the atmosphere of wavelength 589nm and 23 degreeC with the Abbe refractometer. Moreover, about the styrene-type copolymer, it measured at the temperature of 25 degreeC using the potassium iodide saturated aqueous solution as a contact liquid using the digital refractometer (Atago RX-2000).
(7) Resin composition of styrene copolymer: FT-NMR (FX-90Q type, manufactured by JEOL Ltd.) was used as a measurement data by dissolving styrene copolymer in deuterated chloroform to prepare a 2% solution. 13C and calculated from the peak areas of styrene and methyl methacrylate.

Claims (4)

And 30 to 100 wt% styrene monomer units and (meth) styrene copolymer 100 parts by mass consisting of 70 to 0% by weight acrylic acid ester monomer units, average particle size of 2 to 10 [mu] m, The refractive index difference with the styrene-based copolymer is 0.05 to 0.15, and includes a cross-linked copolymer containing methyl methacrylate as a monomer, or methyl methacrylate and n-butyl acrylate as monomers. crosslinked polymer 1-10 parts by weight, a hindered amine compound 0.1 to 2 parts by weight, the styrenic resin composition that contains a benzotriazole compound 0.1-2 parts by weight, further europium compound from 0.005 to 0 A molded body made of a styrene-based resin composition containing 5 parts by mass , the thickness of which is 1 to 7 mm . The molded article according to claim 1, wherein the europium compound is a compound represented by the following structural formulas (A) to (C) or a mixture thereof.
(A) Y (PV) O; Eu ³⁺ , (B) (BaMg) Al ₁₁ O _18.5 Eu ³⁺ , (C) (BaMg) Al ₈ O ₁₀ Eu ²⁺ The molded body according to claim 1 or 2 , wherein the molded body is an injection molded body. The molded body according to claim 1 or 2 , wherein the molded body is an extruded molded body.