JP2014181315A - Transparent styrene-based thermoplastic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent styrene-based thermoplastic resin composition excellent in balance of shock resistance and flowability and having high level transparency.SOLUTION: There is provided a transparent styrene-based thermoplastic resin composition containing a graft copolymer (A) obtained by graft-polymerizing a monomer mixture containing at least an aromatic vinyl monomer (a1), a (meth)acrylic ester monomer (s2) and a vinyl cyanide monomer (a3) in a presence of a rubbery polymer, and a vinyl copolymer (B) obtained by copolymerizing a monomer mixture (b) containing at least an aromatic vinyl monomer (b1), a (meth)acrylic ester monomer (b2) and a vinyl cyanide monomer (b3), and having transmittance of a light having a wavelength of 700 nm by a spectrophotometer measurement of 88% or more and transmittance of a light having a wavelength of 450 nm satisfying the following formula (1): 450 nm transmittance=(%)≥90-0.5×R, where R represents rubbery polymer percent content in the transparent styrene-based thermoplastic resin composition (wt.%).

Description

  The present invention relates to a transparent styrenic thermoplastic resin composition having an excellent balance between impact resistance and fluidity, and particularly having high transparency.

  Rubber polymers such as diene rubber, aromatic vinyl compounds such as styrene and α-methylstyrene, vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, and unsaturated carboxylic acid alkyl esters such as methyl methacrylate and methyl acrylate Transparent ABS resin containing a graft copolymer copolymerized with a compound is excellent in mechanical strength balance such as transparency, impact resistance, rigidity, molding processability, and cost performance. Widely used in related equipment and general goods.

  Until now, the transparent expression technique of transparent ABS resin makes the difference in refractive index between the acetone insoluble part and the acetone soluble part of the rubber-reinforced styrene resin less than 0.02, as in Patent Document 1 and Patent Document 2. Method, using polybutadiene rubber as in Patent Document 3, adjusting the refractive index of acetone-soluble component of butadiene rubber reinforced resin to 1.514 to 1.520, and further adjusting the refractive index of acetone-soluble component and acetone-insoluble component The difference in refractive index between the rubbery polymer component and the acetone-soluble component of the thermoplastic resin composition is adjusted to 0.03 or less as described in Patent Document 4, A method has been proposed in which the difference in refractive index between the crystalline polymer and the graft component is 0.03 or less. However, in any of the methods, there are cases where the application to be used is limited due to insufficient transparency using the transmittances of 700 nm and 450 nm in the spectrophotometer measurement as an index.

JP 2002-128848 A JP 2003-277454 A JP 2002-3548 A JP 2002-212369 A

  The present invention aims to solve the above-described problems in the prior art, that is, a transparent styrene-based thermoplastic resin composition having a particularly high degree of transparency while having a good balance between impact resistance and fluidity. It is intended to provide.

  As a result of diligent studies to achieve the above object, the present inventors have found that a thermoplastic copolymer in which a rubbery polymer-containing graft copolymer is dispersed in a vinyl copolymer obtained by copolymerizing a vinyl monomer mixture. When adjusting the resin composition, it has been found that when specific conditions are satisfied, a transparent styrene-based thermoplastic resin composition having an excellent balance of impact resistance, fluidity, and color tone and particularly high transparency can be obtained. The present invention has been reached.

That is, the transparent styrenic thermoplastic resin composition of the present invention comprises at least an aromatic vinyl monomer (meth) acrylate monomer and a vinyl cyanide monomer in the presence of a rubbery polymer. A graft copolymer (A) obtained by graft polymerization of a monomer mixture containing a monomer, and a monomer containing at least an aromatic vinyl monomer, a (meth) acrylic acid ester monomer, and a vinyl cyanide monomer It contains a vinyl copolymer (B) obtained by copolymerizing a monomer mixture (b), and has a transmittance of light of 700 nm or more and a transmittance of light of 450 nm or more as measured by a spectrophotometer. 450 nm transmittance (%) ≧ 90−0.5 × R, wherein the rate satisfies the following formula (1): Formula (1)
R: Rubber polymer content (% by weight) in the transparent styrene-based thermoplastic resin composition.

  According to the present invention, it is possible to obtain a transparent styrenic thermoplastic resin composition having particularly high transparency while being excellent in the balance between impact resistance and fluidity.

The transparent styrenic thermoplastic resin composition of the present invention has a difference between the refractive index of the rubbery polymer and the refractive index of the vinyl copolymer (B), the refractive index of the rubbery polymer and the vinyl in the rubbery polymer. The difference between the refractive index of the acetone-soluble component (non-grafting component) of the graft copolymer (A) obtained by graft copolymerization of the monomeric monomer mixture, the refractive index of the rubbery polymer and the rubbery polymer The difference between the refractive index of the vinyl copolymer (graft component) contained in the acetone-insoluble matter of the graft copolymer (A) obtained by graft copolymerization of the monomer mixture is the same or slightly different from each other. High transparency that cannot be achieved by the styrene-based thermoplastic resin composition, specifically, the transmittance of light at a wavelength of 700 nm as measured by a spectrophotometer is 88% or more, and the transmittance of light at a wavelength of 450 nm is expressed by the following formula (1 ) Level of transparency It is obtained.
450 nm transmittance (%) ≧ 90−0.5 × R Formula (1)
R: Rubber polymer content (% by weight) in the transparent styrene-based thermoplastic resin composition.

  With respect to the above formula (1), the right side of the formula (1) means that the transparency of the resin composition decreases as the rubber polymer content of the resin composition increases, and satisfies the formula (1). This means that the transmittance of the resin composition does not decrease more than the influence that the transmittance of light having a wavelength of 450 nm of the resin composition decreases by blending the rubbery polymer.

  The R value in the above formula (1) is the weight ratio of the rubber polymer to the total weight of the resin component of the transparent styrene thermoplastic resin composition. For example, the graft copolymer (A) and the vinyl copolymer In the case of the combination (B), the weight ratio of the rubber polymer to the weight of the components (A) and (B) is obtained. The R value is preferably in the range of 5 to 25, more preferably 8 to 20. If the R value is less than 5, impact resistance may be reduced. On the other hand, if it exceeds 25, the transmittance of light having a wavelength of 450 nm may be reduced, which may impair high transparency. .

  The details of the transparent styrenic thermoplastic resin composition will be described below.

  The transparent styrenic thermoplastic resin composition of the present invention comprises at least an aromatic vinyl monomer (a1), a (meth) acrylate monomer (a2), and a vinyl cyanide monomer in the presence of a rubbery polymer. Graft copolymer (A) obtained by graft polymerization of monomer mixture (a) containing monomer (a3), and at least aromatic vinyl monomer (b1), (meth) acrylic acid ester It contains a vinyl copolymer (B) obtained by copolymerizing a monomer mixture (b) containing a monomer (b2) and a vinyl cyanide monomer (b3).

  The rubbery polymer used for the graft copolymer (A) is not particularly limited, and examples thereof include polybutadiene, polyisoprene, natural rubber, styrene-butadiene copolymer, and acrylonitrile-butadiene copolymer. Diene rubbery polymers such as polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer are preferred, and polybutadiene is more preferred.

  The weight average particle diameter of the rubbery polymer is preferably 0.2 to 0.4 μm, more preferably 0.25 to 0.35 μm. When the weight average particle diameter of the rubbery polymer used for the graft copolymer (A) is less than 0.2 μm, the impact resistance of the transparent styrenic thermoplastic resin composition may be lowered. On the other hand, when the weight average particle diameter of the rubbery polymer used for the graft copolymer (A) exceeds 0.4 μm, the transparency of the transparent styrene-based thermoplastic resin composition may be lowered. .

  Although there is no restriction | limiting in the gel content rate of a rubber-like polymer, In order to improve impact resistance and transparency, Preferably it is 80 weight% or more.

  The monomer mixture (a) used for the graft copolymer contains at least an aromatic vinyl monomer (a1), an unsaturated carboxylic acid alkyl ester monomer (a2), and a vinyl cyanide monomer. (A3) is included, but other monomers (a4) copolymerizable with these monomers may be included as long as the transparency is not impaired.

  Examples of the aromatic vinyl monomer (a1) include styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, vinyltoluene, and t-butylstyrene. preferable. These can be used alone or in combination of two or more.

  Examples of the unsaturated carboxylic acid alkyl ester monomer (a2) include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, (meth ) T-butyl acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, chloromethyl (meth) acrylate, and the like, and methyl (meth) acrylate is preferred. These can be used alone or in combination of two or more.

  Examples of the vinyl cyanide monomer (a3) include acrylonitrile, methacrylo, tolyl, ethacrylonitrile and the like, and acrylonitrile is preferred. These can be used alone or in combination of two or more.

  Examples of the other monomer (a4) include unsaturated fatty acids such as itaconic acid, maleic acid, fumaric acid, acrylic acid and methacrylic acid, and acrylamide monomers such as acrylamide, methacrylamide and N-methylacrylamide, Use of maleimide monomers such as N-methylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-hexylmaleimide, N-octylmaleimide, N-dodecylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, etc. Can do. These can be used alone or in combination of two or more.

  The graft copolymer (A) is obtained by graft polymerization of the monomer mixture (a) in the presence of a rubbery polymer. As a ratio of the rubbery polymer and the monomer mixture (a), the rubbery polymer is preferably 30 to 70% by weight, more preferably 40 to 60% by weight, and the monomer mixture (a) is preferably 70%. -30% by weight, more preferably 60-40% by weight. When the rubbery polymer is less than 30% by weight and the monomer mixture is more than 70% by weight, the productivity can be lowered and the cost can be increased. On the other hand, when the rubbery polymer exceeds 70% by weight and the monomer mixture is less than 30% by weight, the dispersibility of the rubbery polymer is lowered and the impact resistance may be lowered.

  The graft copolymer (A) includes a rubber polymer in which a copolymer of the vinyl monomer mixture (a) is graft-bonded and a rubber polymer in which the vinyl monomer mixture (a) is copolymerized. Including those in which the polymer is not graft-bonded, the component containing the rubber polymer is acetone-insoluble, and the copolymer of the vinyl monomer mixture (a) not graft-bonded to the rubber polymer is acetone. Can be classified as a soluble component (hereinafter referred to as “non-grafted component”).

  The graft ratio of the graft copolymer (A) is not particularly limited, but is preferably 5 to 150%, more preferably 30 to 100% from the viewpoint of impact resistance.

  The difference in refractive index between the rubbery polymer and the non-graft component in the graft copolymer (A) and the difference in refractive index between the rubbery polymer and the graft component are each preferably within 0.001. When the difference in refractive index exceeds 0.001, there is a possibility that the transmittance of 450 nm and 700 nm as measured by a spectrophotometer or any one of them may be lowered.

  The refractive index of the rubbery polymer is a value obtained by measuring a rubbery polymer processed into a film using an Abbe refractometer.

The refractive index (nD) of the graft component and the non-graft component can be calculated by the formula (2) described below after quantifying the composition from the following peak appearing in the FT-IR chart.
Aromatic vinyl monomer (a1): peak at 1605 cm ⁻¹ attributed to vibration of the benzene nucleus Unsaturated carboxylic acid alkyl ester monomer (a2): C═O stretching vibration of ester carbonyl group 1730 cm ⁻¹ peak attributed to ## STR4 ## Vinyl cyanide monomer: -C≡N 2240 cm −1 peak refractive index (nD) = 1.510 · MA + 1.595 · MS + 1.490 · MM formula (2)
ND: refractive index of copolymer, MA: acrylonitrile content (% by weight), MS: styrene content (% by weight), MM: methyl methacrylate content (% by weight).

  The monomer ratio of the vinyl monomer mixture (a) used for the graft copolymer (A) is not particularly limited as long as the difference in refractive index is satisfied, but the aromatic vinyl monomer unit is not limited. Monomer (a1) 20-30 wt%, unsaturated carboxylic acid alkyl ester monomer (a2) 65-75 wt%, vinyl cyanide monomer (a3) 3-10 wt%, copolymerizable The other monomer (a4) is preferably 0 to 10% by weight.

  Although there is no restriction | limiting in particular in the manufacturing method of a graft copolymer (A), Since the particle diameter adjustment of a rubber-like polymer is easy, it is preferable.

  In the emulsion polymerization of the graft copolymer (A), the monomer charging method is not particularly limited. However, in order to control the refractive index of the graft component and the non-graft component, a vinyl-based monomer as in the examples is used. A method of changing the charged composition ratio of the body mixture (a) during the polymerization is preferably used. When the composition of the monomer mixture is always constant, the refractive index of the graft component and the non-graft component may be different.

  The polymerization initiator used for the emulsion polymerization of the graft copolymerization (A) is not particularly limited, and a peroxide or an azo compound and water-soluble potassium persulfate are used. These initiators can also be used in redox systems.

  In the emulsion polymerization of the graft copolymer (A), a chain transfer agent may be used for the purpose of adjusting the molecular weight and the graft ratio. As the chain transfer agent, mercaptans, terpenes, and the like can be used, and n-octyl mercaptan and t-dodecyl mercaptan are particularly preferably used.

  There is no particular limitation on the emulsifier used for emulsion polymerization of the graft copolymer (A), and various surfactants can be used, and alkali fatty acid salts are particularly preferably used.

  The graft copolymer latex produced by emulsion polymerization is then added with a coagulant to recover the graft copolymer (A) as a powdery solid. An acid or a water-soluble salt can be used as the coagulant. However, as a method of reducing the residual amount of the emulsifier and obtaining a highly transparent resin, the solid is obtained after neutralization by acid neutralization after acid coagulation, and then washed. And drying to obtain the graft copolymer (A).

  The vinyl copolymer (B) of the present invention comprises at least an aromatic vinyl monomer (b1), an unsaturated carboxylic acid alkyl ester monomer (b2), and a vinyl cyanide monomer (b3). Although it is characterized by including, it may contain the other monomer (b4) copolymerizable with these monomers in the range which does not impair transparency.

  Examples of the aromatic vinyl monomer (b1) include styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, vinyltoluene, and t-butylstyrene. preferable. These can be used alone or in combination of two or more.

  Examples of the unsaturated carboxylic acid alkyl ester monomer (b2) include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, (meth ) T-butyl acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, chloromethyl (meth) acrylate, and the like, and methyl (meth) acrylate is preferred. These can be used alone or in combination of two or more.

  Examples of the vinyl cyanide monomer (b3) include acrylonitrile, methacrylo, tolyl, and ethacrylonitrile, with acrylonitrile being preferred. These can be used alone or in combination of two or more.

  Examples of the other monomer (b4) include unsaturated fatty acids such as itaconic acid, maleic acid, fumaric acid, acrylic acid and methacrylic acid, and acrylamide monomers such as acrylamide, methacrylamide and N-methylacrylamide, Use of maleimide monomers such as N-methylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-hexylmaleimide, N-octylmaleimide, N-dodecylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, etc. Can do. These can be used alone or in combination of two or more.

  The difference in refractive index between the vinyl copolymer (B) and the rubbery polymer is preferably within 0.001. The refractive index of the vinyl copolymer (B) is calculated by the formula (2) by quantifying the composition from the following peak appearing on the FT-IR chart in the same manner as the refractive index of the graft copolymer (A). be able to. When the difference in refractive index between the vinyl copolymer (B) and the rubbery polymer exceeds 0.001, there is a possibility that the transmittance of 450 nm and 700 nm or any one of them may be lowered by spectrophotometer measurement. There is.

  The monomer ratio of the vinyl monomer mixture (b) used for the vinyl copolymer (B) is not particularly limited as long as the difference in refractive index is satisfied, but the aromatic vinyl type is not limited. Monomer (b1) 20-30% by weight, unsaturated carboxylic acid alkyl ester monomer (b2) 65-75%, vinyl cyanide monomer (b3) 3-10% by weight, copolymerizable The other monomer (b4) is preferably 0 to 10% by weight.

  Although there is no restriction | limiting in particular in the manufacturing method of a vinyl type copolymer (B), Continuous bulk polymerization or continuous solution polymerization is preferable from the point of the transparency of the thermoplastic resin composition obtained and color stability.

  In the present invention, the method for performing continuous bulk polymerization or the continuous polymerization method is not particularly limited, and any method can be employed. Can do.

  As the polymerization tank, in addition to a mixing type polymerization tank having various stirring blades and various tower reactors, a multi-tube reactor, a kneader reactor, a twin screw extruder, etc. should be used as the polymerization reactor. (See, for example, Assessment of Polymer Production Process 10 “Assessment of High Impact Polystyrene” Polymer Society, January 26, 1989). These polymerization tanks (reactors) can be used in combination of one (tank) or two (tank) or more, but one tank type stirring blade mixing type in that the composition distribution of the vinyl copolymer can be narrowed. The polymerization tank is preferred. The reaction mixture obtained by polymerization in these polymerization tanks or reactors is usually subjected to a demonomer process, and the monomer, solvent and other volatile components are removed. As a method for removing monomer, a uniaxial or biaxial extruder having a vent is used to remove volatile components from a vent hole under normal pressure or reduced pressure, and a plate fin type heater such as a centrifugal type is incorporated in the drum. A method of removing volatile components with an evaporator, a method of removing volatile components with a thin film evaporator such as a centrifugal type, etc., using a multi-tubular heat exchanger, preheating, foaming and flushing to a vacuum chamber to remove volatile components There are methods, and any of these methods can be used. In particular, a single or twin screw extruder having a vent is preferably used.

  In continuous bulk polymerization or continuous solution polymerization of the vinyl copolymer (B), thermal polymerization without using an initiator, initial polymerization using an initiator, thermal polymerization and initiator polymerization can be further performed. It can also be used in combination. The initiator to be used is not particularly limited, but a peroxide or an azo compound is used, and 1,1'-azobiscyclohexane-1-carbonitrile is particularly preferably used.

  In the continuous bulk polymerization or continuous solution polymerization of the vinyl copolymer (B), a chain transfer agent may be used for the purpose of adjusting the molecular weight. As the chain transfer agent, mercaptans, terpenes, and the like can be used, and n-octyl mercaptan and t-dodecyl mercaptan are particularly preferably used.

  The weight average molecular weight of the vinyl copolymer (B) is preferably 70,000 to 300,000, and more preferably 80,000 to 250,000. If the weight average molecular weight of the vinyl copolymer (B) is less than 70,000, the mechanical strength may decrease, and if it exceeds 300,000, the fluidity tends to decrease.

  When the vinyl copolymer (B) is produced by a continuous solution polymerization method, the amount of the solvent is not particularly limited, but from the viewpoint of productivity, it is preferably 30% by weight or less, more preferably, based on the polymerization solution. A solvent amount of 20% by weight or less is used. The solvent to be used is not particularly limited, but ethylbenzene or methyl ethyl ketone is preferable from the viewpoint of polymerization stability, and ethylbenzene is particularly preferable.

  The transparent styrenic plastic resin composition of the present invention is produced by melt-kneading the graft copolymer (A) and the vinyl copolymer (B) with a Banbury mixer, roll, extruder, kneader, or the like. be able to. From the viewpoint of balance of physical properties such as impact resistance, rigidity, and transparency, it is preferable to mix 10-50 parts by weight of the graft copolymer (A) and 90-50 parts by weight of the vinyl copolymer (B). The graft copolymer (A) is preferably 15 to 40 parts by weight and the vinyl copolymer (B) is 85 to 60 parts by weight.

  The transparent styrene-based thermoplastic resin composition of the present invention includes hindered phenol-based, sulfur-containing organic compound-based, phosphorus-containing organic compound-based antioxidants, phenol-based compounds, etc. within a range not impairing the effects of the present invention. Various stabilizers such as acrylate-based heat stabilizers, benzotriazole-based, benzophenone-based, salicylate-based UV absorbers, organic nickel-based, hindered amine-based light stabilizers, higher fatty acid metal salts, higher fatty acid amides Lubricants such as phthalates, phosphates, plasticizers, polybromodiphenyl ether, tetrabromobisphenol-A, brominated epoxy oligomers, brominated polycarbonate oligomers and other halogen-containing compounds, phosphorus compounds, trioxide Flame retardants and flame retardants such as antimony, antistatic agents, carbon black, oxide Emissions, pigments and dyes, water and silicone oil, can be added to a liquid such as liquid paraffin. There is no restriction | limiting in particular about the addition method of these additives, A various method can be used.

  Thus, the transparent styrene-based thermoplastic resin composition of the present invention has an excellent balance between impact resistance and fluidity, and is widely used in fields of application such as home appliances, communication-related equipment and general miscellaneous goods that require particularly high transparency. can do.

  EXAMPLES Hereinafter, although an Example is given and this invention is further explained in full detail, this invention is not limited to these Examples. In Examples and Comparative Examples, “parts” represents “parts by weight” and “%” represents “% by weight” unless otherwise specified.

(1) Weight average particle diameter of rubbery polymer The rubbery polymer latex is diluted and dispersed in an aqueous medium, and the weight average particle is measured by a laser scattering diffraction particle size distribution analyzer “LS 13 320” (Beckman Coulter, Inc.). The diameter was measured.

(2) Gel content of rubbery polymer 100 ml of toluene was added to a predetermined amount (m) [unit: g (about 1 g)] of a rubbery polymer which had been vacuum-dried at 60 ° C. for 5 hours, and the mixture was stirred at room temperature for 24 hours. Left for hours. The toluene solution was filtered through a 100-mesh sieve, the residue was vacuum-dried at 60 ° C. for 5 hours, the weight (n) [unit: g] was measured, and the gel content was calculated from the following formula.
Gel content (%) = (n) / (m) × 100.

(3) Graft ratio of graft copolymer (A) 80 ml of acetone was added to a predetermined amount (m) [unit: g (about 1 g)] of the graft copolymer (A) which was vacuum-dried at 80 ° C. for 4 hours. The solution was refluxed in a hot water bath at 70 ° C. for 3 hours, and the solution was centrifuged at 8800 r / min (10000 G) for 40 minutes. Acetone insoluble matter was filtered, vacuum dried at 80 ° C. for 4 hours, and the weight (n) [unit: g] of acetone insoluble matter was measured by weight measurement, and the graft ratio was calculated from the following formula. Here, L is the rubbery polymer content [unit:% by weight] of the graft copolymer (A).
Graft rate (%) = {[(n) − (m) × L] / [(m) × L]} × 100.

(4) Refractive Index Measurement (4-1) Refractive Index Measurement of Rubber Polymer A rubber polymer latex was placed in a 3 cm square container and dried to prepare a film with a thickness of 30 ± 5 μm. Using this film as a sample, the refractive index was measured using an Abbe refractometer.

(4-2) Refractive index of non-grafted component of graft copolymer (A) 80 ml of acetone was added to about 1 g of the graft copolymer (A), and the mixture was refluxed in a hot water bath at 70 ° C. for 3 hours. / Min (10000 G) for 40 minutes. After the acetone insoluble matter was filtered, the filtrate was concentrated with a rotary evaporator, and the precipitate was vacuum-dried at 80 ° C. for 4 hours to obtain a sample of non-grafted components. An area of each peak appearing on a chart obtained by analyzing a film sample of a non-graft component adjusted to a thickness of 30 ± 5 μm with a heating press set at 220 ° C. and analyzing this film as a sample by FT-IR From this, the monomer composition was determined. The correspondence between each monomer and peak is as follows.
Methyl methacrylate monomer unit: peak of 3460 cm −1 which is a harmonic overtone peak of 1730 cm −1 attributed to C═O stretching vibration of carbonyl group of ester,
Styrene monomer unit: peak at 1605 cm −1 attributed to vibration of the benzene nucleus,
Acrylonitrile monomer unit: peak at 2240 cm −1 attributed to —C≡N stretching.
Furthermore, the refractive index (nD) was calculated | required by following formula (2) from these copolymer compositions.
Refractive index (nD) = 1.510 · MA + 1.595 · MS + 1.490 · MM Formula (2)
However, the values in the formula are as follows.
nD: refractive index of copolymer, MA: acrylonitrile content (% by weight), MS: styrene content (% by weight), MM: methyl methacrylate content (% by weight).

(4-3) Refractive Index of Graft Component of Graft Copolymer (A) 80 ml of acetone was added to about 1 g of the graft copolymer (A) and refluxed in a 70 ° C. hot water bath for 3 hours. Centrifugation was performed for 40 minutes at min (10000 G). Acetone insoluble matter was filtered, vacuum dried at 80 ° C. for 4 hours, and then a film-like sample of acetone insoluble matter adjusted to a thickness of 30 ± 5 μm with a heating press set at 220 ° C. was prepared. Using this film as a sample, the monomer composition by FT-IR was determined by the same operation as in (3-2) above, and then the refractive index (nD) was determined by equation (2).

(4-4) Refractive index measurement of vinyl copolymer (B) Using vinyl copolymer (B) that was vacuum-dried at 80 ° C. for 4 hours, a film was prepared in the same manner as (3-2) above. After preparing a sample and determining the monomer composition by FT-IR, the refractive index (nD) was determined by equation (2).

(5) Transparency (haze value, total light transmittance)
An injection molding machine (“Promat” (registered trademark) 40/25 manufactured by Sumitomo Heavy Industries, Ltd.) in which pellets of a transparent styrenic thermoplastic resin composition dried in an 80 ° C. hot air dryer for 3 hours were set to a cylinder temperature of 230 ° C. ) And the haze value (%) and total light transmittance (%) of the square plate molded product (thickness 3 mm) filled and injection molded were measured using a direct reading haze meter manufactured by Toyo Seiki Co., Ltd.

(6) Transmittance of light with wavelengths of 700 nm and 450 nm as measured by a spectrophotometer A spectrophotometer V capable of measuring a transmittance of 1100 to 200 nm using the square plate molded product (thickness 3 mm) described in (5) above. Using -600 (manufactured by JASCO Corporation), the transmittances at 700 nm and 450 nm were measured.
The transmittance at 700 nm was evaluated according to the following criteria.
○: Transmittance is 88% or more ×; Transmittance is less than 88% The 450 nm transmittance was evaluated according to the following criteria after comparison with the calculation result of the following formula (1).
450 nm transmittance (%) ≧ 90−0.5 × R Formula (1)
However, R: Rubber polymer content (parts by weight) in the transparent styrene-based thermoplastic resin composition
◯: Expression (1) is satisfied ×: Expression (1) is not satisfied

(7) Charpy impact strength A transparent styrene-based thermoplastic resin composition was injection molded, and Charpy impact strength was measured by a method based on ISO179.

(8) Melt flow rate The melt flow rate of the transparent styrene-based thermoplastic resin composition was measured by a method based on ISO1133. The measurement temperature was 220 ° C. and the weight was 98N.

(Reference Example 1) Graft copolymer (A-1)
In a four-necked flask with an internal volume of 5 liters equipped with a stirring blade, 50 parts of polybutadiene latex (rubber polymerization average particle diameter 0.30 μm, gel content 85%, refractive index 1.516) (solid content conversion), pure water 130 Part, 0.4 part of sodium laurate, 0.2 part of glucose, 0.2 part of sodium pyrophosphate, 0.01 part of ferrous sulfate were charged into the reaction vessel, and after nitrogen substitution, the temperature was adjusted to 60 ° C. and stirred. A monomer mixture of 3.2 parts of lower styrene, 1.2 parts of acrylonitrile, 10.7 parts of methyl methacrylate and 0.15 part of t-dodecyl mercaptan was initially added over 45 minutes. Next, an initiator mixture of cumene hydroperoxide 0.3 parts, sodium laurate 1.6 parts and pure water 25 parts was started to initiate polymerization. The initiator mixture was continuously dropped over 5 hours, and simultaneously, a mixture of 2.3 parts of styrene, 0.8 part of acrylonitrile, 7.8 parts of methyl methacrylate, and 0.11 part of t-dodecyl mercaptan was 1 The monomer mixture was continuously added dropwise over time, and then a mixed solution of 6.5 parts of styrene, 17.5 parts of methyl methacrylate and 0.26 parts of t-dodecyl mercaptan was continuously added dropwise over 4 hours. After the monomer mixture was dropped, only the initiator mixture was continuously dropped for 1 hour to complete the polymerization. The latex after the polymerization was coagulated with 1.5% sulfuric acid, then neutralized with sodium hydroxide, washed, centrifuged and dried to obtain a powdered graft copolymer (A-1) (single amount) Body weight ratio: styrene 24%, acrylonitrile 4%, methyl methacrylate 72%). The refractive index of the graft component of the obtained graft copolymer (A-1) is 1.516, the refractive index difference from the rubbery polymer is 0.000, and the refractive index of the non-graft component is 1.516. The difference in refractive index from the rubber polymer was 0.000. The graft ratio was 47%.

(Reference Example 2) Graft copolymer (A-2)
In a four-necked flask with an internal volume of 5 liters equipped with a stirring blade, 50 parts of polybutadiene latex (rubber polymerization average particle diameter 0.30 μm, gel content 85%, refractive index 1.516) (solid content conversion), pure water 130 Part, 0.4 part of sodium laurate, 0.2 part of glucose, 0.2 part of sodium pyrophosphate, 0.01 part of ferrous sulfate were charged into the reaction vessel, and after nitrogen substitution, the temperature was adjusted to 60 ° C. and stirred. A monomer mixture of 3.6 parts of lower styrene, 0.6 part of acrylonitrile, 10.8 parts of methyl methacrylate and 0.13 part of t-dodecyl mercaptan was initially added over 45 minutes. Next, an initiator mixture of cumene hydroperoxide 0.3 part, emulsifier sodium laurate 1.6 part and pure water 25 part was started to initiate polymerization. The initiator mixture was continuously dropped over 5 hours, and simultaneously, a mixture of 8.4 parts of styrene, 1.4 parts of acrylonitrile, 25.2 parts of methyl methacrylate and 0.39 parts of t-dodecyl mercaptan was added in parallel. The monomer mixture was continuously added dropwise over time. After the monomer mixture was dropped, only the initiator mixture was continuously dropped for 1 hour to complete the polymerization. The latex after polymerization was coagulated with 1.5% sulfuric acid, then neutralized with sodium hydroxide, washed, centrifuged and dried to obtain a powdered graft copolymer (A-2) (single amount) Body weight ratio: styrene 24%, acrylonitrile 4%, methyl methacrylate 72%). The graft copolymer (A-2) thus obtained has a graft component refractive index of 1.518, a refractive index difference of 0.002 from the rubber polymer, and a non-graft component refractive index of 1.513. The difference in refractive index from the rubber polymer was 0.003. The graft ratio was 44%.

Reference Example 3 Vinyl copolymer (B-1)
A 2m ³ fully mixed polymerization tank with a condenser for monomer vapor reflux and a helical ribbon blade, a single-screw extruder preheater, and a barrel that is 1/3 long from the tip of the twin-screw extruder demonomer Polymerization and resin mixing were carried out using a continuous bulk polymerization apparatus comprising a twin-screw extruder type feeder having a heating device connected in tandem at the part.

  First, a monomer mixture comprising 23.5 parts of styrene, 4.5 parts of acrylonitrile, 72.0 parts of methyl methacrylate, 0.15 part of n-octyl mercaptan and 0.01 part of di-t-butyl peroxide, The polymer was continuously supplied to the polymerization tank at 150 kg / hour, and continuous bulk polymerization was performed while maintaining the polymerization temperature at 130 ° C. and the internal pressure of 0.08 MPa. The polymerization rate of the polymerization reaction mixture at the exit from the polymerization vessel was controlled between 74 and 76%.

  The polymerization reaction mixture is preheated by a single-screw extruder type preheater, and then unreacted monomers are evaporated and recovered from the vent port under reduced pressure by a twin-screw extruder type demonomer. The mixture was continuously refluxed to the polymerization tank. The polymer discharged in a strand form from the monomer removal machine was cooled and cut with a pelletizer to obtain a pellet-shaped vinyl copolymer (B-1). The resulting vinyl copolymer (B-1) had a refractive index of 1.516, and the difference in refractive index from the rubbery polymer used in Reference Examples 1 and 2 was 0.000.

Reference Example 4 Vinyl copolymer (B-2)
A pellet-like vinyl copolymer was produced in the same manner as in Reference Example 3 except that the composition of the monomer mixture was 21.5 parts of styrene, 4.5 parts of acrylonitrile, and 74 parts of methyl methacrylate. (B-2) was obtained. The resulting vinyl copolymer (B-2) had a refractive index of 1.514, and the difference in refractive index from the rubbery polymer used in Reference Examples 1 and 2 was 0.002.

Reference Example 5 Vinyl copolymer (B-3)
A pellet-like vinyl copolymer was produced in the same manner as in Reference Example 3 except that the composition of the monomer mixture was 25.5 parts of styrene, 4.5 parts of acrylonitrile, and 70 parts of methyl methacrylate. (B-3) was obtained. The obtained vinyl copolymer (B-3) had a refractive index of 1.518, and the difference in refractive index from the rubbery polymer used in Reference Examples 1 and 2 was 0.002.

Example 1
Using a twin screw extruder, 25 parts of the graft copolymer (A-1) obtained in Reference Example 1 and 75 parts of the vinyl copolymer (B-1) obtained in Reference Example 3 were used at 220 ° C. The polymer which was melt-kneaded and discharged in the form of a strand was cooled and then cut to obtain a pellet-like transparent styrene thermoplastic resin composition. The evaluation results of the resin properties are shown in Table 1.

(Example 2)
A transparent styrenic thermoplastic resin composition was obtained in the same manner as in Example 1 except that 35 parts of the graft copolymer (A-1) and 65 parts of the vinyl copolymer (B-1) were used. The evaluation results of the resin properties are shown in Table 1.

(Comparative Examples 1-5)
A transparent styrene thermoplastic resin composition was obtained in the same manner as in Example 1 except that the types of the graft copolymer (A) and the vinyl copolymer (B) were changed as shown in Table 1. The evaluation results of the resin properties are shown in Table 1.

(Comparative Examples 6-8)
A transparent styrene thermoplastic resin composition was obtained in the same manner as in Example 2 except that the types of the graft copolymer (A) and the vinyl copolymer (B) were changed as shown in Table 1. The evaluation results of the resin properties are shown in Table 1.

  As in Examples 1 and 2, the transparent styrenic thermoplastic resin composition of the present invention was excellent in the balance between impact resistance and fluidity, and particularly high transparency was obtained. However, the resin compositions obtained in Comparative Examples 1 to 8 had a transmittance of 450 nm and / or 700 nm measured with a spectrophotometer outside the scope of the present invention, and were inferior in transparency.

  The transparent styrenic thermoplastic resin composition obtained in the present invention has an excellent balance between impact resistance and fluidity, and has particularly high transparency. Therefore, taking advantage of these characteristics, home appliances, communication-related equipment, and general miscellaneous goods. It can be used widely in application fields such as.

Claims (8)

Monomer mixture containing at least an aromatic vinyl monomer (a1), a (meth) acrylic acid ester monomer (a2) and a vinyl cyanide monomer (a3) in the presence of a rubbery polymer Graft copolymer (A) obtained by graft polymerization of (a), at least aromatic vinyl monomer (b1), (meth) acrylate monomer (b2), vinyl cyanide monomer A transparent styrenic thermoplastic resin composition containing a vinyl copolymer (B) obtained by copolymerizing a monomer mixture (b) containing a body (b3), and having a wavelength of 700 nm as measured by a spectrophotometer The transparent styrene-type thermoplastic resin composition characterized by the transmittance | permeability of 88% or more satisfy | filling the transmittance | permeability of light with a wavelength of 450 nm of following formula (1).
450 nm transmittance (%) ≧ 90−0.5 × R Formula (1)
However, R: Rubber polymer content rate (weight%) in a transparent styrene-type thermoplastic resin composition   2. The transparent styrenic thermoplastic resin composition according to claim 1, wherein the rubber-like polymer has a weight average particle diameter of 0.2 to 0.4 [mu] m.   The transparent styrenic thermoplastic resin composition according to claim 1 or 2, comprising 10 to 50 parts by weight of the graft copolymer (A) and 50 to 90 parts by weight of the vinyl copolymer (B).   The graft copolymer (A) contains at least an aromatic vinyl monomer, a (meth) acrylic acid ester monomer, and a vinyl cyanide monomer in the presence of 30 to 70% by weight of a rubbery polymer. The transparent styrenic thermoplastic resin composition according to any one of claims 1 to 3, which is obtained by graft polymerization of 70 to 30% by weight of the monomer mixture (a).   The difference between the refractive index of the rubbery polymer constituting the graft copolymer (A) and the refractive index of the vinyl copolymer (B) is within 0.001. The transparent styrenic thermoplastic resin composition according to any one of the above.   The difference between the refractive index of the rubbery polymer constituting the graft copolymer (A) and the refractive index of the non-graft component of the graft copolymer (A) is within 0.001. The transparent styrene-type thermoplastic resin composition in any one of 1-5.   The difference between the refractive index of the rubbery polymer constituting the graft copolymer (A) and the refractive index of the graft component of the graft copolymer (A) is within 0.001. The transparent styrene-type thermoplastic resin composition in any one of -6.   A molded article formed by molding the transparent styrene-based thermoplastic resin composition according to claim 1.