TW202244065A - Copolymer, resin composition for injection molding, molded article, and method for producing copolymer - Google Patents

Abstract

The present invention provides: a copolymer which comprises an aromatic vinyl monomer unit and a cyano monomer unit, and which has excellent strength, chemical resistance, hue, and translucency when made into a molded article; and a resin for injection molding which comprises said copolymer. Provided is a copolymer comprising an aromatic vinyl monomer unit and a cyano monomer unit, wherein the difference between the maximum value and the minimum value of P(UV)/P(RI) is not more than 0.15, where P(UV) is the peak strength detected for UV 254 nm in the half width of the peak of the weight average molecular weight MwRI of the copolymer as found by a differential refractive index detector in gel permeation chromatography, and P(RI) is the peak strength detected by the differential refractive index detector in the half width of the peak of the MwRI.

Description

Copolymer, resin composition for injection molding, molded article, method for producing copolymer

The present invention relates to a copolymer containing an aromatic vinyl monomer unit and a cyano monomer unit, a resin composition for injection molding containing the copolymer, and a molded article obtained by molding the resin composition.

Copolymers containing aromatic vinyl monomer units and cyano-based monomer units are widely used in various fields due to their excellent properties such as chemical resistance, rigidity, and moldability. As a method for producing these copolymers, various polymerization methods such as emulsion polymerization, suspension polymerization, bulk polymerization, and solution polymerization can be employed. However, since an emulsifier is used in the emulsion polymerization and a dispersant is used in the suspension polymerization, there are problems in the appearance quality of the polymerization product such as transparency and discoloration. Therefore, in consideration of quality, cost, environment, etc., non-aqueous bulk polymerization or solution polymerization is mostly used.

On an industrial production scale, when bulk polymerization or solution polymerization is carried out continuously, the latent heat of evaporation is used, that is, the heat dissipation caused by the evaporation of the gas phase part and the gas-liquid interface of the polymerization liquid is used, or the condenser outside the reaction tank is used to cool the evaporation as needed. The solvent and unreacted monomer are cooled and refluxed into the reaction tank to effectively dissipate heat, so high conversion rate polymerization can be achieved, and it is often used as a polymer method on an industrial production scale.

The methods that have been disclosed include: adjusting the concentration of the condensate returned from the condenser of the polymerizer, and spraying it back to the gas phase part of the polymerizer (Patent Document 1); In the upper gas phase portion of the tank, the condensate returned from the condenser and the raw material liquid are mixed and supplied to the polymerizer (Patent Document 2). [Prior art literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2000-226417 [Patent Document 2] Japanese Unexamined Patent Publication No. 2004-262987

[Problem to be solved by the invention]

In recent years, physical properties including transparency, strength, and hue have been improved, and it is required to reduce the occurrence rate of defective products from this point of view. However, satisfactory results cannot be obtained with copolymers obtained by the above-mentioned techniques.

Therefore, the object of the present invention is to provide a copolymer containing an aromatic vinyl monomer unit and a cyano monomer unit and a resin for injection molding containing the copolymer, which have excellent strength, chemical resistance, And it was excellent in hue and transparency. [means to solve the problem]

The inventors of the present invention conducted intensive studies to solve the above-mentioned problems, and found that when the molecular weight distribution of a copolymer containing an aromatic vinyl monomer unit and a cyano-based monomer unit satisfies the following constitution, the resulting molded product The strength, chemical resistance, hue, and transparency are excellent, and the present invention has been completed. That is, the present invention relates to the following matters. (1) A copolymer comprising an aromatic vinyl monomer unit and a cyano monomer unit, the half-width of the weight-average molecular weight MwRI of the copolymer obtained by gel permeation chromatography using a differential refraction detector When the peak intensity detected by UV254nm is set as P(UV), and the peak intensity detected by the differential refractive index detector in the half width of MwRI is set as P(RI), the ratio of P(UV)/P(RI) The difference between the maximum value and the minimum value is 0.15 or less. (2) The copolymer as described in (1), wherein, when the total of the aromatic vinyl monomer unit and the cyano monomer unit is 100% by mass, the aromatic vinyl monomer unit 50 ~90% by mass and 10~50% by mass of the cyano-based monomer unit. (3) The copolymer according to (1) or (2), wherein the aromatic vinyl monomer unit is a styrene monomer unit, and the cyano-based monomer unit is an acrylonitrile monomer unit. (4) A resin composition for injection molding containing the copolymer described in any one of (1) to (3). (5) A molded article obtained by molding the resin composition for injection molding according to (4). (6) A method for producing a copolymer containing an aromatic vinyl monomer unit and a cyano-based monomer unit, the production method comprising: supplying an aromatic vinyl monomer and a cyano-based monomer a step of supplying liquid to the liquid phase of the polymerization liquid in the reaction tank; and condensing the evaporated gas generated in the reaction tank using a heat exchanger outside the reaction tank, and returning the obtained condensate to the reaction tank Liquid phase steps. [Invention effect]

According to the present invention, there is provided a copolymer excellent in strength, chemical resistance, hue, and transparency when molded. The resin composition according to the present invention can be applied to miscellaneous goods such as containers such as cosmetics and stationery that require high designability.

＜Regulations on molecular weight distribution of copolymers＞ For the copolymer containing an aromatic vinyl monomer unit and a cyano monomer unit according to the present embodiment, Gel Permeation Chromatography (hereinafter sometimes abbreviated as "GPC") is used to determine When the peak intensity detected with UV254nm in the half-width of the weight-average molecular weight MwRI of MwRI is set as P(UV), and the peak intensity detected by a differential refraction detector in the half-width of MwRI is set as P(RI), P( The difference between the maximum value and the minimum value of UV)/P(RI) is 0.15 or less, preferably 0.10 or less. Specifically, it is, for example, 0.15 or less, 0.13 or less, 0.11 or less, 0.10 or less, 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, or 0.05 or less. If the difference between the maximum value and the minimum value of P(UV)/P(RI) exceeds 0.15, the hue of the molded product may be deteriorated. A copolymer having a difference between the maximum value and the minimum value of P(UV)/P(RI) of 0.15 or less can be obtained, for example, by the production method described below, but is not limited thereto.

In the GPC measurement, tetrahydrofuran (hereinafter sometimes abbreviated as "THF") can be used as a mobile phase. MwRI is a value in terms of polystyrene, and can be measured under the following conditions. Device name: SYSTEM-21 Shodex (manufactured by Showa Denko Co., Ltd.) Column: 3 PL gel MIXED-B (manufactured by Polymer Laboratories Ltd.) connected in series Temperature: 40°C Solvent: THF Concentration: 0.4% by mass Standard curve: drawn using standard polystyrene (PS) (manufactured by Polymer Laboratories Ltd.)

In the GPC measurement of the present embodiment, a GPC apparatus having a differential refractive index detector and an absorbance detector and capable of simultaneously performing measurement using these detectors is used. The absorbance detector is configured to be able to measure absorbance at a wavelength of 254 nm. In the molecular weight distribution obtained by GPC measurement, the concentration of each component contained in each molecular weight in the distribution was measured using a differential refractometer, and the absorbance (measurement wavelength: 254 nm) of each molecular weight component was measured using an absorbance detector. It should be noted that the measurement wavelength of 254 nm is derived from the structure of the benzene ring. The absorbance detector may be a detector for measuring ultraviolet light absorption at a specific wavelength, or a detector for spectroscopically measuring ultraviolet light absorption at a specific range of wavelengths.

The half-peak width of the weight-average molecular weight MwRI refers to: use the value measured by the differential refractive index detector to draw a chromatogram, use the dissolution time showing the maximum peak intensity value in the chromatogram as the peak, and give half of the maximum peak intensity value The width of the dissolution time before and after the peak in the dissolution time of the value. In addition, even when the peak is multimodal, the dissolution time showing the maximum peak intensity value is used as a reference. In addition, there may be more than two dissolution times giving a value half of the maximum peak intensity value, and in this case, it refers to the width of dissolution times before and after the farthest peak among such dissolution times.

The peak intensities P(RI) and P(UV) represent the following peak intensities: with respect to the molecular weight of the resin converted from the GPC dissolution capacity, the values measured by the differential refraction detector and the values measured by the absorbance detector (determined Wavelength 254 nm) The peak intensity in the above-mentioned half-width range in each chromatogram plotted from the measured value.

<Copolymer containing aromatic vinyl monomer unit and cyano monomer unit> The copolymer according to this embodiment contains an aromatic vinyl monomer unit and a cyano monomer unit. In addition, monomer units other than the aromatic vinyl monomer unit and the cyano monomer unit may be contained within the range that does not inhibit the effect of the present invention. The monomer units constituting the copolymer containing an aromatic vinyl monomer unit and a cyano-based monomer unit according to the present embodiment will be described below.

＜Aromatic vinyl monomer unit＞ The monomer providing the aromatic vinyl monomer unit contained in the copolymer according to the present embodiment is not particularly limited, and examples thereof include styrene, α-methylstyrene, p-methylstyrene, 3, 5 - Dimethylstyrene, 4-methoxystyrene, 2-hydroxystyrene and other substituted styrenes, alpha-bromostyrene, 2, 4-dichlorostyrene and other halogenated styrenes, 1 -Vinyl naphthalene etc. Among them, styrene is preferable from the viewpoints of polymerizability, moldability, and mechanical properties.

＜Cyano-based monomer unit＞ There are no particular limitations on the monomer providing the cyano-based monomer unit contained in the copolymer according to the present embodiment. Acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethacrylonitrile, etc. are mentioned. Among them, acrylonitrile is preferable from the viewpoint of polymerizability, mechanical properties, and the like.

The content ratio of the aromatic vinyl monomer unit and the cyano-based monomer unit in the copolymer in this embodiment can be selected arbitrarily, and the amount of the aromatic vinyl monomer unit contained in 100% by mass of the copolymer is preferably 50 % by mass to 90% by mass, more preferably 55% by mass to 88% by mass, further preferably 60% by mass to 85% by mass. Specifically, for example, 50% by mass, 55% by mass, 60% by mass, 65% by mass, 70% by mass, 75% by mass, 80% by mass, 85% by mass, or 90% by mass, or any two numerical values exemplified here in the range between. The amount of the vinyl cyanide-based monomer contained in 100% by mass of the copolymer is preferably 10% by mass to 50% by mass, more preferably 12% by mass to 45% by mass, even more preferably 15% by mass to 40% by mass. Specifically, for example, it is 10 mass %, 15 mass %, 20 mass %, 25 mass %, 30 mass %, 35 mass %, 40 mass %, 45 mass %, or 50 mass %, or any two numerical values exemplified here in the range between. If each monomer is outside the above-mentioned composition range, it may be difficult to achieve the object of the present invention: the appearance of the molded article, chemical resistance, transparency, mechanical properties, and the like.

<Monomer units other than aromatic vinyl monomer units and cyano-based monomer units> The copolymer in this embodiment may also be copolymerized with a copolymerizable monomer other than vinyl cyanide-based monomers and aromatic vinyl monomers within a range that does not inhibit the effects of the present invention. Examples of other vinyl compounds that can be copolymerized with vinyl cyanide-based monomers and aromatic vinyl monomers include methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, Acrylic esters such as esters, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride and itaconic acid or their anhydrides, N-phenylmaleimide, N-cyclohexylmaleimide and other horses As imide compounds and the like, ethyl acrylate and butyl acrylate are particularly preferred, and two or more of these may be used in combination.

When the total of monomer units derived from vinyl cyanide-based monomer units, aromatic vinyl monomer units, and monomers copolymerizable with them is 100% by mass, the copolymer contained in the present embodiment The content of these monomer units is 0% by mass to 20% by mass, preferably 0% by mass to 5% by mass.

＜Resin composition＞ The resin composition in this embodiment is a resin composition containing a copolymer containing an aromatic vinyl monomer unit and a cyano monomer unit. The content of the copolymer of the aromatic vinyl monomer unit and the cyano monomer unit in 100% by mass of the resin composition is, for example, 50% by mass or more. In one aspect, the content of the copolymer in the resin composition is preferably 80% by mass or more, more preferably 90% by mass or more. Specifically, for example, it is 50, 55, 60, 65, 70, 75, 80, 85, or 90% by mass or more. In one embodiment, the resin composition may consist substantially only of a copolymer containing an aromatic vinyl monomer unit and a cyano-based monomer unit.

The resin composition in this embodiment may contain mineral oil in the range which does not inhibit the effect of this invention. In addition, internal lubricants such as stearic acid and ethylenebisstearamide, phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, lactone antioxidants, ultraviolet absorbers, hindered amine antioxidants, etc. may also be included. Stabilizer, antistatic agent, external lubricant and other additives. The method of adding these additives includes a method of adding and mixing in a polymerization step, a devolatilization step, and a granulation step; or a method of adding and mixing using an extruder, an injection molding machine, etc. during molding, and the like, and is not particularly limited.

The ultraviolet absorber is an additive that has a function of suppressing deterioration and coloring due to ultraviolet rays, and examples thereof include benzophenone-based, benzotriazole-based, triazine-based, benzoate-based, salicylate-based, Cyanoacrylate-based, oxalylaniline-based, malonate-based, formamidine-based, and other ultraviolet absorbers. These may be used alone or in combination of two or more, and may be used in combination with light stabilizers such as hindered amines.

In order to express various designs, the resin composition in this embodiment may further contain various dyes and pigments within the range that does not hinder the effects of the present invention. Examples include coumarin-based fluorescent dyes, benzopyran-based fluorescent dyes, perylene-based fluorescent dyes, anthraquinone-based fluorescent dyes, thioindigo-based fluorescent dyes, xanthene-based fluorescent dyes, oxa Anthrone-based fluorescent dyes, thioxanthene-based fluorescent dyes, thioxanthone-based fluorescent dyes, thiazine-based fluorescent dyes, diaminostilbene-based fluorescent dyes, and the like. Based on a total of 100 parts by mass of additives such as antioxidants in the resin composition, the content of the dye and pigment is preferably 0.00001 to 1 part by mass, more preferably 0.00003 to 0.3 part by mass.

<Method for producing a copolymer containing an aromatic vinyl monomer unit and a cyano monomer unit> As a method for producing a copolymer containing an aromatic vinyl monomer unit and a cyano-based monomer unit in this embodiment, a suspension polymerization method, a solution polymerization method, a bulk polymerization method, etc. can be used to prevent the dispersant from being mixed into the resin. In view of the purpose, it is preferable to use a solution polymerization method or a bulk polymerization method.

＜Polymerization device＞ The polymerization device used in this embodiment is a complete mixing tank type polymerizer (I) having a heat exchanger for condensing the steam in the gas phase; or the polymerizer (I) and one or more polymerizers connected thereto (II) Composition. As the polymerizer (II), a complete mixing tank type polymerizer, a pipe type polymerizer, an extruder type polymerizer, a kneader type polymerizer, etc. can be used.

Embodiments for making the polymerization liquid in the polymerizer (I) substantially uniform are not particularly limited, except that ribbon-type stirring blades such as helical ribbon blades, turbine-type stirring blades, helical-type stirring blades, anchor blades, and inclined paddles are used. In addition to stirring and mixing with paddle blades such as blades or flat blades, FULL ZONE blades (trade name), Maxblend blades (trade name) or SANMELER blades (trade name), for example, stirring and mixing can also be combined with the use of equipment Combination of circulatory mixing by pumps etc. outside the polymerizer (I) is carried out.

As a heat exchanger used in this embodiment, a spray condenser, a shell-and-tube condenser, etc. are mentioned, for example.

The solvent used in this embodiment is an inactive polymerization solvent usually used in radical polymerization, and examples thereof include ethylbenzene, toluene, xylene, o-xylene, m-xylene, p-xylene, cumene, and n-propylbenzene , cumene and other aromatic hydrocarbons; 2-butanone, methyl isobutyl ketone and other ketones; N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone isoamide compounds. Among these solvents, ethylbenzene is preferable from the viewpoint of devolatilization and economic efficiency.

The usage-amount of a solvent is preferably 5-40 mass parts with respect to 100 mass parts of monomer mixture liquids, More preferably, it is 10-35 mass parts. Since the viscosity of a polymerization liquid becomes high when it is less than 5 mass parts, a polymerization rate cannot fully be improved, and productivity is insufficient. On the other hand, if it exceeds 40 parts by mass, the amount of the devolatilized solvent will increase, resulting in poor economic efficiency.

As the polymerization initiator added in this embodiment, known polymerization initiators can be used, for example, ketone peroxides such as methyl ethyl ketone peroxide, 1,1-bis(t-butylperoxy)3,3,5-tris Peroxyketals such as methylcyclohexane, 2,2-bis(4,4-di-tert-butylperoxycyclohexyl)propane, hydroperoxides such as cumene hydroperoxide, diisopropyl peroxide Dialkyl peroxides such as propylbenzene, diacyl peroxides such as benzoyl peroxide, peroxydicarbonates such as diisopropyl peroxydicarbonate, t-butyl peroxyisopropyl carbonate Peroxyesters, 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile) and other azonitriles, allyl tert-butyl peroxy Organic peroxides such as carbonate, trimethyl(tert-butylperoxy)silane, 3,3',4,4'-tetrakis(tert-butylperoxycarbonyl)benzophenone, etc. Among these polymerization initiators, tert-butyl peroxyisopropyl carbonate is preferable from the viewpoint of hue and economical efficiency. These polymerization initiators may be used individually or in mixture of 2 or more types.

As long as the amount of the polymerization initiator used is within the range capable of controlling the removal of the reaction heat in the polymerization apparatus, it is advantageous that the larger the amount is, the faster the reaction rate will be. However, if the reaction rate is too fast, disadvantages such as coloring may occur. The practical amount used varies depending on the type of polymerization initiator and the polymerization temperature, but is preferably 0.005 to 0.5 parts by mass, more preferably 0.01 to 0.4 parts by mass, based on 100 parts by mass of the total amount of monomers.

In the production of the copolymer according to this embodiment, as the chain transfer agent, for example, t-dodecyl mercaptan, n-dodecyl mercaptan, unsaturated dimer of α-methylstyrene, terpene Pinolene, octyl thioglycolate, etc.

The amount of the chain transfer agent used varies depending on the type of the chain transfer agent, and is preferably 5 parts by mass or less, more preferably greater than 0 and 3 parts by mass or less, and even more preferably 1 to 3 parts by mass relative to 100 parts by mass of the total monomers 0.001 parts by mass. If it is more than 5 parts by mass, the molecular weight of the copolymer of the aromatic vinyl monomer unit and the cyano-based monomer unit will be too small, and there will be problems such as being unable to express practical strength.

Polymerization of the copolymer according to the present embodiment is carried out, for example, as follows.

＜Preparation of supply solution＞ First, a supply liquid containing a solvent, a polymerizable monomer, a polymerization initiator, a chain transfer agent, and the like in predetermined proportions is prepared.

<Supplying the supply liquid to the reaction tank> The supply liquid is supplied to the reaction tank by continuously supplying the supply liquid to the liquid phase of the polymerization liquid. The supply rate at the time of supplying the supply liquid to the liquid phase of the polymerization liquid also depends on the temperature described later and the controlled polymerization rate, and is preferably adjusted so that the residence time in the polymerization tank becomes 2 to 6 hours. If the residence time is too short, the hue may deteriorate, and if the residence time is too long, productivity may be poor.

＜Polymerization of monomer＞ Polymerization is carried out by maintaining the polymerization temperature within a predetermined range. The polymerization temperature varies depending on the type of initiator used, but is preferably 120 to 180°C. When the polymerization temperature is adjusted to this range, the polymerization can be easily controlled, and the deterioration of the hue can be suppressed while increasing the polymerization rate.

＜Controlling the filling rate of the reaction solution＞ The filling rate of the reaction liquid was maintained within a predetermined range, and the reaction liquid was continuously withdrawn in an amount equivalent to the supply liquid. The filling rate of the reaction liquid in the reaction tank is preferably 50 to 100 vol%. By carrying out polymerization in this range, the productivity is excellent.

＜Evaporative gas condensation＞ The evaporated gas generated in the reaction tank enters the heat exchanger outside the reaction tank through the steam pipe, where it is condensed into condensate. This condensate is returned to the liquid phase of the reaction tank via the supply pipe.

＜Copolymer recycling＞ The extracted reaction liquid is degassed to recover unreacted monomers and organic solvents, and the copolymer is recovered in the form of particles.

The copolymer in this embodiment is produced by, for example, the above-mentioned production method, and the peak intensity detected at UV254nm in the half width of the weight average molecular weight MwRI is defined as P(UV), and the half width of MwRI is used When the peak intensity detected by the differential refractive index detector is P(RI), the difference between the maximum and minimum values of P(UV)/P(RI) is 0.15 or less.

The difference between the maximum value and the minimum value of P(UV)/P(RI) indicates the composition distribution of the aromatic vinyl monomer unit and the cyano monomer unit in the resin. For P(UV) detected by absorbance (measurement wavelength: 254 nm), the peak intensity changes according to the concentration of the monomer having a benzene ring, that is, the aromatic vinyl monomer unit. On the other hand, P(RI) depends on the concentration of the entire molecule, so P(UV)/P(RI) shows a constant value regardless of the molecular weight, indicating that there is no difference in the composition distribution even if the molecular weight changes.

The mechanism by which the difference between the maximum value and the minimum value of the P(UV)/P(RI) of the copolymer is less than 0.15 by this production method is not very clear. Therefore, the composition distribution of the copolymer will be generated, but in the production method according to this embodiment, the supply liquid is supplied to the liquid phase of the polymerization liquid and the condensate is returned to the liquid phase of the reaction tank, so there is no department supply. Therefore, the composition distribution of the copolymer is reduced, and even if the molecular weight of the copolymer is changed, the difference in composition distribution is reduced.

<Method for producing a resin composition containing a copolymer comprising an aromatic vinyl monomer unit and a cyano-based monomer unit> Mineral oil, additives, dyes, and the like are added as necessary to the copolymer of the aromatic vinyl monomer unit and the cyano-based monomer unit obtained as described above to obtain a resin composition. Addition of additives includes a method of adding and mixing in a polymerization step, a devolatilization step, and a granulation step, or a method of adding and mixing using an extruder or an injection molding machine during molding, but is not limited thereto.

The molded article obtained by molding the resin composition according to this embodiment can be processed into miscellaneous goods such as stationery, cosmetic containers, home appliance casings, etc., which require high design. In addition, the resin composition according to the present embodiment may be used alone, or may be suitably mixed with other resins such as ABS resin and PC resin to be used as a mixed resin. [Example]

The details are described below using examples, but the present invention is not limited to the following examples.

<Example 1> The supply solution supplied to the 50L reaction tank was prepared as 70 parts by mass of styrene, 15 parts by mass of acrylonitrile, 15 parts by mass of ethylbenzene, 0.02 parts by mass of tert-butyl peroxyisopropyl carbonate as a polymerization initiator, and 0.02 parts by mass of tert-butyl peroxyisopropyl carbonate as a chain transfer agent. 0.01 parts by mass of n-dodecylmercaptan. Nitrogen gas was bubbled through the supply liquid, and after passing through the mixer, it was continuously supplied to the liquid phase of the polymerization liquid at a rate of 10.8 L/hour and supplied to the reaction tank. The polymerization temperature was 145° C. The reaction liquid was used so that the filling rate of the reaction liquid in the reaction tank could be maintained at 70 vol%. It should be noted that the evaporated gas generated in the reaction tank is condensed in the heat exchanger outside the reaction tank, and the condensate is returned to the liquid phase of the reaction tank. The withdrawn reaction solution was introduced into a volatile component removal device maintained at 250°C and a high vacuum of 10 mmHg to degas and recover unreacted monomers and organic solvents, and recover the copolymer in the form of particles.

<Example 2> The supply solution supplied to the 50L reaction tank was prepared as 58 parts by mass of styrene, 22 parts by mass of acrylonitrile, 20 parts by mass of ethylbenzene, 0.02 parts by mass of tert-butyl peroxyisopropyl carbonate as a polymerization initiator, and 0.02 parts by mass of tert-butyl peroxyisopropyl carbonate as a chain transfer agent. 0.04 parts by mass of n-dodecylmercaptan. Nitrogen gas was bubbled through the supply liquid, and after passing through the mixer, it was continuously supplied to the liquid phase of the polymerization liquid at a rate of 8 L/hour and supplied to the reaction tank. liquid so that the filling rate of the reaction liquid in the reaction tank can be maintained at 60vol%. It should be noted that the evaporated gas generated in the reaction tank is condensed in the heat exchanger outside the reaction tank, and the condensate is returned to the liquid phase of the reaction tank. The extracted reaction solution was introduced into a volatile component removal device under the same conditions as in Example 1, unreacted monomers and organic solvents were degassed and recovered, and the copolymer was recovered in the form of particles.

<Example 3> The feed solution supplied to the 50L reaction tank was prepared as 49 parts by mass of styrene, 29 parts by mass of acrylonitrile, 23 parts by mass of ethylbenzene, 0.02 parts by mass of tert-butyl peroxyisopropyl carbonate as a polymerization initiator, and 0.02 parts by mass of tert-butyl peroxyisopropyl carbonate as a chain transfer agent. 0.12 parts by mass of n-dodecylmercaptan. Nitrogen gas was bubbled to the supply liquid, and after passing through the mixer, it was continuously supplied to the liquid phase of the polymerization liquid at a rate of 9.8 L/hour and then supplied to the reaction tank. The polymerization temperature was 145° C. The reaction liquid was used so that the filling rate of the reaction liquid in the reaction tank could be maintained at 80 vol%. It should be noted that the evaporated gas generated in the reaction tank is condensed in the heat exchanger outside the reaction tank, and the condensate is returned to the liquid phase of the reaction tank. The extracted reaction solution was introduced into a volatile component removal device under the same conditions as in Example 1, unreacted monomers and organic solvents were degassed and recovered, and the copolymer was recovered in the form of particles.

<Example 4> The feed solution supplied to a 50L reaction tank was prepared as 78 parts by mass of styrene, 7 parts by mass of acrylonitrile, 15 parts by mass of ethylbenzene, 0.02 parts by mass of tert-butyl peroxyisopropyl carbonate as a polymerization initiator, and 0.02 parts by mass of tert-butyl peroxyisopropyl carbonate as a chain transfer agent. 0.01 parts by mass of n-dodecylmercaptan. Nitrogen gas was bubbled through the supply liquid, and after passing through the mixer, it was continuously supplied to the liquid phase of the polymerization liquid at a rate of 10.8 L/hour and supplied to the reaction tank. The polymerization temperature was 145° C. The reaction liquid was used so that the filling rate of the reaction liquid in the reaction tank could be maintained at 70 vol%. It should be noted that the evaporated gas generated in the reaction tank is condensed in the heat exchanger outside the reaction tank, and the condensate is returned to the liquid phase of the reaction tank. The extracted reaction solution was introduced into a volatile component removal device under the same conditions as in Example 1, unreacted monomers and organic solvents were degassed and recovered, and the copolymer was recovered in the form of particles.

＜Comparative example 1＞ Resin pellets were obtained in the same manner as in Example 1 except that the supply liquid was continuously introduced from the gas phase of the polymerization liquid.

＜Comparative example 2＞ Resin pellets were obtained in the same manner as in Example 1 except that the evaporated gas generated in the reaction tank was condensed in the heat exchanger outside the reaction tank, and the condensate was returned to the gaseous phase of the reaction tank.

＜Comparative example 3＞ Resin pellets were obtained in the same manner as in Example 1 except that the supply liquid was continuously sprayed from the gas phase of the polymerization liquid and the supply liquid was introduced from the liquid phase.

＜Comparative example 4＞ Resin pellets were obtained in the same manner as in Example 1 except that the supply liquid was only styrene.

＜GPC measurement＞ After running continuously for 360 hours under the conditions described in the Examples and Comparative Examples, the particles were collected, and GPC was carried out under the above conditions to determine the maximum and minimum values of P(UV)/P(RI) and the difference between the two.

<GPC measurement conditions> Device name: SYSTEM-21 Shodex (manufactured by Showa Denko Co., Ltd.) Column: 3 PL gel MIXED-B (manufactured by Polymer Laboratories Ltd.) connected in series Temperature: 40°C Solvent: THF Concentration: 0.4% by mass Standard curve: drawn using standard polystyrene (PS) (manufactured by Polymer Laboratories Ltd.)

＜Preparation of samples＞ 60 mg of the copolymer was dissolved in 15 mL of THF (tetrahydrofuran) at room temperature, and filtered through a 0.45 μm syringe filter to prepare a sample. It should be noted that the injection volume was 10 μL.

＜Measurement of peak intensity P(RI) and P(UV)＞ Relative to the molecular weight of the resin converted from the GPC dissolution capacity in the above-mentioned GPC measurement, use the value measured by the differential refraction detector and the value measured by the absorbance detector (measurement wavelength 254m) respectively to draw a chromatogram, and The peak intensities in the above half-width ranges in each chromatogram were taken as P(RI) and P(UV), respectively.

＜Preparation of resin composition test pieces＞ After continuous operation for 360 hours under the conditions described in Examples and Comparative Examples, 100% by mass of the collected particles was mixed with the antioxidant 4,4',4''-(1-methacryl-3-ylidene ) tris(6-tert-butyl-m-cresol) (ADEKASTAB AO-30 manufactured by ADEKA Corporation) 0.15% by mass, tris(2,4-di-tert-butylphenyl) phosphite (ADEKASTAB 2112 manufactured by ADEKA Corporation) ) 0.05% by mass, extruded and granulated using a single-screw extruder (MS-40 manufactured by IKG Co., Ltd.). The pellets were used to produce test pieces with an injection molding machine, and various physical property values were measured.

＜Charpy Impact Strength＞ Using the obtained pellets, the measurement was performed at a relative humidity of 50% and an ambient temperature of 23° C. using an unnotched test piece in accordance with JIS K-7111 and using edgewise in the striking direction. It should be noted that a digital impact tester manufactured by Toyo Seiki Seisakusho was used as a measuring device.

＜Transmittance, YI value＞ Using the obtained pellets, a plate-like molded product with a thickness of 127×127×3 mm was molded at a molding temperature of 230° C. using an injection molding machine (J140AD-180H, manufactured by Nippon Steel Corporation). A test piece having a thickness of 115×85×3 mm was cut out from the plate-shaped molded product, and the end surface was polished and ground to obtain a plate-shaped molded product having a mirror surface on the end surface. Using a UV-Vis spectrophotometer V-670 manufactured by JASCO Co., Ltd. to measure the polished plate-shaped molded product under incident light with a size of 20×1.6mm and a divergence angle of 0°, the 350nm~800nm when the optical path length is 115mm is measured. According to JIS K7105, calculate the YI value under the wavelength C light source and the field of view of 2°. In addition, the transmittance represents the total light transmittance in the range of 430 to 700 nm. The results are shown in Table 1.

＜Haze＞ Based on ASTM D-1003, it measured using the haze meter (NDH-2000) manufactured by Nippon Denshoku Kogyo Co., Ltd. using the 127*127*3 mm thick plate-shaped molded article molded under the said conditions.

＜Chemical Resistance＞ In order to exclude the influence of molding strain, each pellet was press-molded at 260° C. to a thickness of 4 mm, and a 50 mm×50 mm square was cut out to manufacture a test piece. After 14 days of immersion in each chemical reagent set at 40°C, the samples were classified according to the following criteria based on weight change and appearance change. Chemical reagents use salad oil. ◎: Almost no influence of weight change, appearance change, etc. was observed ○: Slight turbidity or discoloration observed △: Slight cracks or cracks appear ×: Dissolved or greatly affected

[Table 1]

Examples 1 to 4, in which the difference between the maximum value and the minimum value of P(UV)/P(RI) was small, were excellent in strength, and excellent in transparency, YI value, and Haze (haze) value. Comparative Examples 1 to 3 in which the difference between the maximum and minimum values of P(UV)/P(RI) was large had low intensity, high YI value, and poor hue. [industrial availability]

The resin composition containing the copolymer of the present invention and the molded article molded from the resin composition are excellent in strength and chemical resistance, and excellent in hue and transparency, so they are suitable for applications requiring high designability. Specifically, it can be applied to containers for cosmetics and other miscellaneous goods such as stationery.

Claims (6)

A copolymer comprising an aromatic vinyl monomer unit and a cyano-based monomer unit, Let the peak intensity detected at UV254nm in the half-width of the weight-average molecular weight MwRI of the copolymer obtained by gel permeation chromatography using a differential refractive index detector be P(UV), and the half-width of MwRI using differential When the peak intensity detected by the refraction detector is P(RI), the difference between the maximum and minimum values of P(UV)/P(RI) is 0.15 or less. The copolymer as claimed in item 1, wherein, When the total of the aromatic vinyl monomer unit and the cyano-based monomer unit is 100% by mass, the aromatic vinyl monomer unit is 50-90% by mass and the cyano-based monomer unit is 10-90% by mass. 50% by mass. The copolymer as claimed in item 1 or 2, wherein, The aromatic vinyl monomer unit is a styrene monomer unit, and the cyano-based monomer unit is an acrylonitrile monomer unit. A resin composition for injection molding, which contains the copolymer described in any one of claims 1 to 3. A molded article obtained by molding the resin composition for injection molding according to claim 4. A kind of manufacture method of copolymer, described copolymer contains aromatic vinyl monomer unit and cyano system monomer unit, described manufacture method comprises: a step of supplying a supply liquid containing an aromatic vinyl monomer and a cyano-based monomer to a liquid phase of a polymerization liquid in a reaction tank; and A step of condensing the evaporated gas generated in the reaction tank using a heat exchanger outside the reaction tank, and returning the obtained condensate to the liquid phase of the reaction tank.