TW202106732A - Methacrylic copolymer and shaped product - Google Patents

Abstract

A methacrylic copolymer comprising 85.0 to 95.0 % by mass of a monomer unit derived from methyl methacrylate and 5.0 to 15.0 % by mass of a monomer unit derived from an acrylic acid ester, wherein the copolymer has a weight average monomer weight Mw of 48000 to 59000, a ratio Mw/Mn of the weight average monomer weight Mw relative to a number average monomer weight Mn of not more than 2.1, and a ratio Tg/R of a glass transition temperature Tg relative to a melt flow rate R as measured at condition of 230 °C and 3.8 kg-load of 5.0 to 1.5 °C･10min/g.

Description

Methacrylic acid copolymer and molded products

The present invention relates to methacrylic acid copolymers and molded products. More specifically, the present invention relates to a methacrylic acid copolymer having excellent fluidity during thermoforming and less mold contamination, and a molded product having high heat resistance and high mechanical strength.

Methacrylic resin has high transparency and is useful as a material for molded articles such as optical members, lighting members, sign members, and decorative members. In several fields where methacrylic resin molded products are used, there is a demand for lighter or thinner molded products. In order to obtain a thin molded product, it is necessary for the methacrylic resin to have high fluidity when it is melted. As a method for improving the fluidity of resins, generally known: lowering the softening temperature or glass transition temperature, lowering the molecular weight, broadening the molecular weight distribution, and the like. However, if these methods are applied to methacrylic resins, it will cause a decrease in heat resistance, a decrease in mechanical strength, and the like. Considering such a situation, Citations 1 to 3 propose various methacrylic resins and their production methods. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] WO 2013/161265 A1 [Patent Document 2] JP 2017/178975 A [Patent Document 3] WO 2017/146169 A1

[The problem to be solved by the invention]

The subject of the present invention is to provide a methacrylic acid copolymer with excellent fluidity during thermoforming and less mold contamination, and a molded product with high heat resistance and high mechanical strength. [Means to solve the problem]

In order to solve the above-mentioned problems, it has been repeatedly discussed, and as a result, the present invention including the following aspects has been completed.

[1] A methacrylic acid copolymer comprising 85.0-95.0% by mass of monomer units derived from methyl methacrylate and 5.0-15.0% by mass of monomer units derived from acrylate, The weight average molecular weight Mw is 48000～59000, The ratio Mw/Mn of the weight average molecular weight Mw to the number average molecular weight Mn is 2.1 or less, and The ratio Tg/R of the glass transition temperature Tg to the melt flow rate R under the conditions of 230°C and a load of 3.8 kg is 5.0 to 1.5°C·10 min/g. [2] The methacrylic acid copolymer as described in [1], wherein the amount of bonded sulfur atoms relative to the monomer unit derived from methyl methacrylate is 0.4 mol% or less, and the melt flow rate R is 25 g/10 minutes or more.

[3] A thermoplastic resin composition containing the methacrylic acid copolymer as described in [1] or [2] and acrylic rubber particles. [4] The thermoplastic resin composition as described in [3], which further contains an acrylic block copolymer. [5] The thermoplastic resin composition according to [3] or [4], wherein the acetone-insoluble component contained in the thermoplastic resin composition is 59% by mass or less, and The acetone-soluble component contained in the thermoplastic resin composition has a ratio Tg/R of the glass transition temperature Tg to the melt flow rate R under the conditions of 230°C and a 3.8 kg load of 6.0 to 1.5°C·10 min/g.

[6] A pellet-shaped molding material comprising the methacrylic acid copolymer as described in [1] or [2]. [7] A molded article containing the methacrylic acid copolymer as described in [1] or [2]. [8] The molded product as described in [7], which has a plate shape with a thickness of 0.5 mm or less. [9] A housing for a mobile phone terminal, which contains the methacrylic acid copolymer as described in [1] or [2]. [10] A housing for a mobile phone terminal, which has a portion containing the methacrylic acid copolymer as described in [1] or [2] with a thickness of 0.8 mm or less. [11] An optical member containing the methacrylic acid copolymer as described in [1] or [2].

[12] A method for producing a methacrylic acid copolymer, which is the method for producing a methacrylic acid copolymer as described in [1] or [2], comprising: making a monomer containing methyl methacrylate and acrylate The body is polymerized by the bulk polymerization method.

[13] A method of manufacturing a methacrylic acid copolymer, comprising: 100 parts by mass of monomers containing at least 81.0-94.2% by mass of methyl methacrylate and 5.8-19.0% by mass of acrylate, 0.42 to 0.52 parts by mass of chain transfer agent, and polymerization initiator with an average residence time of 1.5-3 hours It is supplied to a continuous flow-through reactor without using a solvent at a temperature of 110 to 140°C, and is polymerized at a polymerization conversion rate of 35 to 65%, Secondly, heating at 220～260℃ to remove unreacted monomers; The methacrylic acid copolymer series: containing 85-95.0% by mass of structural units derived from methyl methacrylate and 5.0-15.0% by mass of structural units derived from acrylate, The weight average molecular weight Mw is 48000～59000, The ratio Mw/Mn of the weight average molecular weight Mw to the number average molecular weight Mn is 2.1 or less, and A methacrylic acid copolymer whose glass transition temperature Tg is a methacrylic acid copolymer whose ratio Tg/R to the melt flow rate R under the conditions of 230°C and a load of 3.8 kg is 5.0 to 1.5°C·10 min/g. [Effects of Invention]

The methacrylic acid copolymer of the present invention has excellent fluidity and is not prone to forming defects such as silver streaks, cracks, sink marks, flow marks, resin burnt, gas pollution, and coloring. The molding material containing the methacrylic acid copolymer of the present invention is suitable for injection molding. The molding material containing the methacrylic acid copolymer of the present invention is suitable for obtaining a thin molded product, for example, a plate having a thickness of 0.5 mm or less. The molded product containing the methacrylic acid copolymer of the present invention has high heat resistance and mechanical strength, and has no appearance defects such as coloring. The molding material containing the methacrylic acid copolymer of the present invention has low heat generation due to shearing force, and an injection molded product with good appearance can be obtained even at a low temperature and a high injection pressure.

[Form to implement the invention]

The methacrylic acid copolymer of this invention contains the monomer unit derived from methyl methacrylate and the monomer unit derived from acrylate. The content of the monomer unit derived from methyl methacrylate is 85.0-95.0% by mass, preferably 85.0-93.5% by mass, more preferably 87.5-93.5% by mass, and still more preferably 88-93.5% by mass. The content of the monomer unit derived from acrylate is 5.0 to 15.0% by mass, preferably 6.5 to 15.0% by mass, more preferably 6.5 to 12.5% by mass, and still more preferably 6.5 to 12% by mass. In the methacrylic acid copolymer of the present invention, the total of monomer units derived from methyl methacrylate and monomer units derived from acrylate is preferably 99% by mass or more, and more preferably 100% by mass.

Examples of acrylates include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, pentyl acrylate, hexyl acrylate, octyl acrylate, tetradecyl acrylate, dodecyl acrylate, and hexadecyl acrylate. Acrylate, octadecyl acrylate, behenyl acrylate and other linear alkyl acrylates; isopropyl acrylate, isobutyl acrylate, tertiary butyl acrylate, 2-ethylhexyl acrylate and other branched alkyl acrylates ; Cyclic alkyl acrylates such as cyclohexyl acrylate; aryl acrylates such as phenyl acrylate; aralkyl acrylates such as benzyl acrylate and the like. Among these, the linear, branched or cyclic alkyl acrylate is preferred, and the linear alkyl acrylate is more preferred. The alkyl group in the alkyl acrylate preferably has a carbon number of 1-18, more preferably 1 or 2, and even more preferably 1.

The methacrylic acid copolymer of the present invention may have monomer units derived from methyl methacrylate and monomer units other than monomer units derived from acrylate. Examples of such monomers include: ethyl methacrylate Acyclic C2 or higher methacrylic acid alkyl esters such as butyl methacrylate, hexyl methacrylate, heptyl methacrylate, etc., preferably methacrylic acid acyclic C2 or higher C7 or lower alkyl ester; Bicyclo[3.2.1]octyl acrylate, tricyclo[3.2.1.0 ^2,7 ]octyl methacrylate, tricyclo[5.2.1.0 ^2,6 ]decyl methacrylate, 3,9 methacrylate: Cyclic alkyl methacrylates such as 8,10-dimethyl bridge tricyclo[4.2.1.1 ^2,5 ]decyl ester; aromatic vinyl groups such as styrene and methyl styrene, etc. The content of these monomer units is preferably 1% by mass or less. In addition, "C2 or more and C7 or less" means that the number of carbon atoms constituting the alkyl group is 2 or more and 7 or less.

From the viewpoint of toughness, surface hardness, etc., the weight average molecular weight Mw of the methacrylic acid copolymer of the present invention and the ratio Mw/Mn of the weight average molecular weight Mw to the number average molecular weight Mn are both in the following ranges. That is, the weight average molecular weight Mw of the methacrylic acid copolymer of the present invention is 48,000 to 59,000, preferably 48,000 to 55,000, more preferably 49,000 to 53,000, and the ratio of the weight average molecular weight Mw to the number average molecular weight Mn Mw/Mn It is 2.1 or less, preferably 1.7 or more and 2.0 or less. The weight average molecular weight Mw and the number average molecular weight Mn are values calculated by converting a chart measured by gel permeation chromatography into the molecular weight of standard polystyrene.

The ratio of the glass transition temperature Tg of the methacrylic acid copolymer of the present invention to the melt flow rate R under the conditions of 230°C and a load of 3.8 kg, Tg/R is 5.0 to 1.5°C·10 min/g, preferably 4.0 ～1.5℃・10min/g, more preferably 3.5～1.5℃・10min/g, still more preferably 3.3～1.5℃・10min/g. The glass transition temperature is based on JIS K7121, using a differential scanning calorimetry device (made by Shimadzu Corporation, DSC-50 (model)). The temperature is raised to 230°C at one degree, then cooled to room temperature, and then heated from room temperature at 10°C/min. Measure the DSC curve at 230°C. It is based on the intermediate point glass transition temperature (Tmg) determined by the DSC curve measured during the second heating. The melt flow rate is a value measured under the conditions of 230°C, a load of 3.8 kg, and 10 minutes in accordance with JIS K7210.

The lower limit of the melt flow rate R of the methacrylic acid copolymer of the present invention measured at 230°C under a load of 3.8 kg is preferably 15 g/10 min, more preferably 25 g/from the viewpoints of formability, toughness, etc. 10 points, the upper limit is preferably 60 g/10 points.

In the methacrylic acid copolymer of the present invention, the amount of bonded sulfur atoms relative to the monomer unit derived from methyl methacrylate is preferably 0.4 mol% or less, more preferably 0.3 to 0.38 mol%, and still more preferably It is 0.31～0.36mol%. The amount of sulfur bonding is related to imparting good moldability, less mold contamination, and high fluidity to the methacrylic acid copolymer. An amount of a sulfur atom bonded to the lines of the embodiment are as follows as the decision value S _p. The methacrylic acid copolymer was dissolved in chloroform to obtain a solution. This solution was added to n-hexane to obtain a precipitate. The precipitate was dried under vacuum at 80°C for more than 12 hours. The obtained dried product is accurately weighed and installed in a sulfur combustion device, decomposed by a reaction furnace at a temperature of 400°C, and the generated gas is passed through a furnace at a temperature of 900°C, followed by absorption with 0.3% hydrogen peroxide water. The obtained liquid (decomposition gas aqueous solution) is appropriately diluted with pure water, and sulfuric acid ions are quantified by ion chromatography (ICS-1500 manufactured by DIONEX, column: AS12A). The amount of bonded sulfur atoms (mol %) relative to the monomer unit derived from methyl methacrylate was calculated from _{the mass W p} (mass %) of sulfur atoms per mass of the dried product.

The manufacturing method of the methacrylic acid copolymer of the present invention is not particularly limited. For example, it can be produced by a well-known polymerization reaction such as a radical polymerization reaction and an anionic polymerization reaction. In the present invention, radical polymerization is preferred. The polymerization reaction can be carried out by a suspension polymerization method, a bulk polymerization method, a solution polymerization method, or an emulsion polymerization method. Among these polymerization methods, in view of less mixing of impurities, the bulk polymerization method is preferred. In the bulk polymerization method, it is preferable to set the polymerization conversion rate to 35 to 65%. The bulk polymerization method is preferably carried out by a continuous flow method. In the continuous flow-through block polymerization method, it is preferable to set the average residence time of the reactor to 1.5 to 3 hours.

The preferred production method of the methacrylic acid copolymer of the present invention includes: polymerizing monomers containing methyl methacrylate and acrylate by a block polymerization method, preferably at least 81.0 to methyl methacrylate. 94.2% by mass and 5.8-19.0% by mass of acrylate monomers are polymerized by the bulk polymerization method, and more preferably, the monomers containing 81.0-91.9% by mass of methyl methacrylate and 8.1-19.0% by mass of acrylate are polymerized as a block Shape polymerization method to polymerize. Acrylic esters are related to imparting high fluidity and high melt flow rate R to the methacrylic acid copolymer. In addition to methyl methacrylate and acrylate, the monomers supplied to the polymerization may also include: methacrylic acid acyclic C2 or higher alkyl ester (preferably methacrylic acid acyclic C2 or more C7 alkyl ester) , Cyclic alkyl methacrylate; aromatic vinyl such as styrene, methyl styrene, etc. The content of these monomers other than methyl methacrylate and acrylate is preferably 1% by mass or less. In the production method of the present invention, the total of methyl methacrylate and acrylate contained in the monomer supplied to polymerization is preferably 99% by mass or more, and more preferably 100% by mass.

The polymerization reaction is carried out using a polymerization initiator, a predetermined monomer, and a chain transfer agent as needed. The temperature during the polymerization is preferably 100 to 150°C, more preferably 110 to 140°C, and still more preferably 120 to 140°C. There is a tendency that the lower the polymerization temperature, the higher the heat resistance of the methacrylic acid copolymer of the present invention.

The polymerization initiator used in the present invention is not particularly limited. Examples include azo-based polymerization initiators such as azobisisobutyronitrile; peroxide-based polymerization initiators such as tertiary hexyl isopropyl peroxymonocarbonate. The polymerization initiator used in the present invention preferably has a temperature half-life of 1 second to 1 minute at the time of polymerization. If the amount of polymerization initiator used is reduced, the methacrylic acid copolymer of the present invention tends to reduce mold contamination. From the standpoint of reducing mold contamination, for example, azobisisobutyronitrile may be preferably 0.02 parts by mass or less, more preferably 0.002 parts by mass or more with respect to 100 parts by mass of the total monomers supplied for polymerization. Use 0.01 parts by mass or less.

The chain transfer agent used in the present invention is not particularly limited. For example, thiol-based chain transfer agents such as n-octyl mercaptan and n-dodecyl mercaptan; α-methylstyrene dimer; terpinolene and the like can be cited. The amount of the chain transfer agent used is preferably 0.42 to 0.52 parts by mass relative to 100 parts by mass of the total monomers supplied to the polymerization. The more the thiol chain transfer agent is used, the more the amount of bonded sulfur atoms relative to the monomer unit derived from methyl methacrylate. From the viewpoint of good injection moldability, less mold contamination, and improved fluidity, for example, relative to the total 100 parts by mass of the monomers to be polymerized, the n-octyl mercaptan can be preferably 0.3 parts by mass or more 0.6 parts by mass or less, more preferably 0.41 parts by mass or more and 0.50 parts by mass or less.

After the polymerization reaction, it is preferable to remove the unreacted monomer from the reaction product. The removal of unreacted monomers is preferably carried out by a heating devolatile method at a temperature of 220 to 260°C. In the heating devolatile method, it can be ideally used: a device for heating the liquid containing the reaction product discharged from the reactor, such as a heat exchanger, and a device for removing volatile components from a liquid heated to a predetermined temperature by a heating device It has an extruder with vent holes. Extruders with vent holes usually include a cylinder and a screw. The cylinder is provided with a hopper (introduction port for the liquid containing the reaction product), a rear vent is provided on the upstream side of the hopper, a front vent is provided on the downstream side of the hopper, and a polymer drain is provided at the lowest flow. Export etc. Moreover, it is preferable to set the temperature and pressure in the hopper and the cylinder by flashing the heated liquid in the hopper. The removed volatile components are discharged from the rear vent and the front vent. Furthermore, it is preferable to add volatile components discharged by inert gas such as nitrogen to the rear vent and/or the front vent after passing through the rear vent and/or the front vent. In addition, the screw may be either a single-shaft type or a double-shaft type. The screw can be configured to release pressure at a portion corresponding to the front vent hole. For example, the shaft diameter of the screw in this part can be made smaller than the shaft diameter of the screw in other parts. In addition, it can be installed: a valve mechanism with a power valve currently installed in the front vent, a left-hand threaded part on the current screw of the front vent, and a bypass mechanism connecting the bypass before and after the front vent in the cylinder.

The thermoplastic resin composition of the present invention contains the methacrylic acid copolymer of the present invention and acrylic rubber particles.

Examples of acrylic rubber particles include: an outer layer composed of a thermoplastic polymer (P) and an inner layer composed of a crosslinked elastomer that is in contact with the outer layer and covered, and the inner layer and the outer layer are formed to form the core And the shell is better. The inner layer contains a core and an inner shell. The acrylic rubber particles include, for example, a two-layer polymer in which the core (inner layer) is a cross-linked rubber polymer (Q)-the outer layer (outer layer) is a thermoplastic polymer (P), and the core (inner layer) is a cross-linked polymer (R)-Inner shell (inner layer) is a cross-linked rubber polymer (Q)-Outer shell (outer layer) is a 3-layer polymer of thermoplastic polymer (P), and the core (inner layer) is a cross-linked rubber polymer (Q) )-The first inner shell (inner layer) is a cross-linked polymer (R)-The second inner shell (inner layer) is a cross-linked rubber polymer (Q)-The outer shell (outer layer) is a thermoplastic polymer (P) 4 Layer polymer, etc.

From the viewpoint of transparency, it is preferable to select the polymer contained in each layer so that the difference in refractive index between adjacent layers is preferably less than 0.005, more preferably less than 0.004, and still more preferably less than 0.003.

The quality ratio of the inner layer and the outer layer in the acrylic rubber particles is preferably 60/40 to 95/5, more preferably 70/30 to 90/10. In the inner layer, the ratio of the layer containing the crosslinked rubber polymer (Q) is preferably 20 to 70% by mass, more preferably 30 to 50% by mass.

The average particle diameter of the acrylic rubber particles is preferably 0.05 to 3 μm, more preferably 0.1 to 1 μm, and still more preferably 0.15 to 0.2 μm. By having an average particle size in such a range, especially having an average particle size of 0.15 to 0.2 μm, a small amount of blending can be used to express toughness, so rigidity and surface hardness are not impaired. In addition, the average particle diameter in this specification is the average value of the volume-based particle diameter distribution measured by the light scattering method.

The thermoplastic polymer (P) is a polymer containing an alkyl methacrylate unit having an alkyl group having 1 to 8 carbon atoms and, if necessary, a monofunctional monomer unit other than the alkyl methacrylate. The thermoplastic polymer (P) preferably does not contain a multifunctional monomer unit.

Relative to the mass of the thermoplastic polymer (P), the amount of the alkyl methacrylate unit having a C 1-8 alkyl group constituting the thermoplastic polymer (P) is preferably 80-100% by mass, More preferably, it is 85 to 95% by mass.

As an alkyl methacrylate having an alkyl group having 1 to 8 carbon atoms (hereinafter sometimes referred to as C1-8 alkyl methacrylate), for example, methyl methacrylate is preferred.

Relative to the mass of the thermoplastic polymer (P), the amount of monofunctional monomer units other than the C1-8 alkyl methacrylate constituting the thermoplastic polymer (P) is preferably 0-20% by mass, and more Preferably, it is 5 to 15% by mass. Examples of monofunctional monomers other than C1-8 alkyl methacrylate include acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and propyl acrylate; styrene, etc. Aromatic vinyl compounds.

Relative to the acrylic rubber particles, the amount of the thermoplastic polymer (P) is preferably 40 to 75% by mass, more preferably 45 to 70% by mass, and still more preferably 50 to 65% by mass.

The cross-linked elastomer layer of the inner layer has an intermediate layer composed of a cross-linked rubber polymer (Q), and an inner layer composed of a cross-linked polymer (R) and connected to and covered with the aforementioned intermediate layer.

The crosslinked polymer (R) contains methyl methacrylate units, monofunctional monomer units other than methyl methacrylate, and polyfunctional monomer units.

The amount of methyl methacrylate units constituting the crosslinked polymer (R) is preferably 40-98.5% by mass, more preferably 45-95% by mass relative to the mass of the crosslinked polymer (R).

Relative to the mass of the crosslinked polymer (R), the amount of monofunctional monomer units other than methyl methacrylate constituting the crosslinked polymer (R) is 1 to 59.5% by mass, preferably 5 to 55 quality%. Examples of monofunctional monomers other than methyl methacrylate include acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and propyl acrylate; aromatic vinyl groups such as styrene Compound.

The amount of the multifunctional monomer unit constituting the crosslinked polymer (R) is preferably 0.05 to 0.4% by mass, and more preferably 0.1 to 0.3% by mass relative to the mass of the crosslinked polymer (R). Examples of multifunctional monomers include ethylene glycol dimethacrylate, propylene glycol dimethacrylate, triethylene glycol dimethacrylate, hexanediol dimethacrylate, and ethylene glycol diacrylate. , Propylene glycol diacrylate, triethylene glycol diacrylate, allyl methacrylate, triallyl isocyanate, etc.

With respect to the acrylic rubber particles, the amount of the crosslinked polymer (R) is preferably from 5 to 40% by mass, more preferably from 7 to 35% by mass, and still more preferably from 10 to 30% by mass.

The crosslinked rubber polymer (Q) contains an alkyl acrylate unit and/or a conjugated diene unit having an alkyl group having 1 to 8 carbon atoms, and a multifunctional monomer unit.

Relative to the mass of the cross-linked rubber polymer (Q), the amount of alkyl acrylate units and/or conjugated diene units having a C 1-8 alkyl group constituting the cross-linked rubber polymer (Q) The content is preferably from 85 to 99% by mass, more preferably from 95 to 98% by mass.

Examples of the alkyl acrylate having an alkyl group having 1 to 8 carbon atoms include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and propyl acrylate.

Relative to the mass of the crosslinked rubber polymer (Q), the amount of the multifunctional monomer unit constituting the crosslinked rubber polymer (Q) is preferably 1 to 1.7% by mass, more preferably 1.2 to 1.6% by mass , More preferably 1.3 to 1.5% by mass. Examples of the polyfunctional monomer include those exemplified in the crosslinked polymer (R).

From the viewpoint of improving the bending resistance, the quality of the multifunctional monomer unit in the crosslinked polymer (R) is better than the quality of the multifunctional monomer unit in the crosslinked rubber polymer (Q). 0.05 to 0.25, more preferably 0.1 to 0.2. The glass transition temperature of the crosslinked rubber polymer (Q) is preferably lower than the glass transition temperature of the crosslinked polymer (R).

With respect to the amount of acrylic rubber particles, the amount of the crosslinked rubber polymer (Q) is preferably 20 to 55% by mass, more preferably 25 to 45% by mass, and still more preferably 30 to 40% by mass.

The average diameter of the inner layer of acrylic rubber particles is preferably 60 to 110 nm, more preferably 65 to 105 nm, and still more preferably 70 to 100 nm. The average diameter of the inner layer can be determined as follows. Using a hydraulic pressure forming machine, when the mold size is 50mm×120mm, the pressure temperature is 250°C, the preheating time is 3 minutes, the pressure pressure is 50kg/cm ² , the pressure time is 30 seconds, the cooling temperature is 20°C, and when cooling Under the conditions of a pressure of 50 kg/cm ² and a cooling time of 10 minutes, the resin composition containing acrylic rubber particles was molded into a flat plate with a thickness of 3 mm. Using a microtome, the obtained flat plate was cut in a direction parallel to the long side at -100°C to obtain a sheet with a thickness of 40 nm, and the sheet was dyed with ruthenium. The stained sheet was observed and photographed with a scanning transmission electron microscope (JSM7600F manufactured by JEOL Ltd.) at an acceleration voltage of 25 kV. Measure the short and long diameters of the ruthenium-stained part (the exposed section of the cross-linked elastomer layer), use (short diameter + long diameter)/2 as the diameter of the inner layer, measure 20 or more, and calculate the number Average (average diameter).

The acrylic rubber particles are not particularly limited due to the production method. For example, emulsification polymerization etc. are mentioned. In the case of emulsion polymerization, for example, the monomer (r) used to form the crosslinked polymer (R) can be subjected to emulsion polymerization to obtain a latex containing the crosslinked polymer (R), which is added to form a crosslinked rubber polymer ( Q) For the monomer (q) used, the monomer (q) is subjected to nucleus emulsion polymerization to obtain a latex containing the crosslinked polymer (R) and the crosslinked rubber polymer (q), which is added to form a thermoplastic polymer ( P) The used monomer (p), the monomer (p) is subjected to nucleus emulsion polymerization to obtain a latex containing acrylic rubber particles. In addition, emulsion polymerization is a well-known method used in order to obtain polymer-containing latex. Nucleus seed emulsion polymerization is a method of polymerizing monomers on the surface of seed particles. In order to obtain core-shell structure polymer particles, core seed emulsion polymerization is ideally used.

The thermoplastic resin composition of the present invention may further contain an acrylic block copolymer.

The acrylic block copolymer preferably contains a polymer block (b1) mainly containing methacrylate units and a polymer block (b2) mainly containing acrylate units. The number of polymer blocks (b1) in one molecule of the acrylic block copolymer may be 1, or may be 2 or more. In addition, the number of polymer blocks (b2) in one molecule of the acrylic block copolymer may be 1, or may be 2 or more.

The amount of methacrylate units contained in the polymer block (b1) is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and still more preferably 98% by mass or more. As the methacrylate, for example, methyl methacrylate is preferred. The methacrylate can be used for the polymer block (b1) alone or in combination of two or more.

From the viewpoints of transparency, flexibility, bending resistance, impact resistance, flexibility, molding processability, surface smoothness, etc., the amount of polymer block (b1) contained in the acrylic block copolymer It is preferably 40% by mass or more and 90% by mass or less, and more preferably 45% by mass or more and 80% by mass or less.

The glass transition temperature of the polymer block (b2) is preferably 20°C or lower, more preferably -20°C or lower.

The amount of acrylate units contained in the polymer block (b2) is preferably 90% by mass or more. As acrylate, n-butyl acrylate, benzyl acrylate, etc. are mentioned, for example. These acrylates can be used for the polymer block (b2) alone or in combination of two or more.

As long as the purpose and effects of the present invention are not hindered, the polymer block (b2) may contain monomer units other than acrylate.

From the viewpoint of transparency and the like, the polymer block (b2) preferably contains an alkyl acrylate unit and an aromatic (meth)acrylate unit. The quality ratio of the alkyl acrylate unit/(meth)acrylic acid aromatic ester is preferably 50/50 to 90/10, more preferably 60/40 to 80/20.

The bonding form of the polymer block (b1) and the polymer block (b2) contained in the acrylic block copolymer is not particularly limited. Preferably, for example: one end of the polymer block (b2) is connected to one end of the polymer block (b1) (b1-b2 diblock copolymer); at both ends of the polymer block (b2) Respectively connect one end of the polymer block (b1) (b1-b2-b1 triblock copolymer).

The weight average molecular weight of the acrylic block copolymer is preferably 52,000 or more and 400,000 or less, more preferably 60,000 or more and 300,000 or less. In addition, the ratio of the acrylic block copolymer-based weight average molecular weight to the number average molecular weight is preferably 1.01 or more and 2.00 or less, more preferably 1.05 or more and 1.60 or less. From the viewpoints of moldability, tensile strength, appearance, etc., the weight average molecular weight and number average molecular weight of the acrylic block copolymer can be appropriately set. The weight average molecular weight and the number average molecular weight are the standard polystyrene conversion values measured by GPC (gel permeation chromatography).

The acrylic block copolymer is not particularly limited due to its production method, and it can be obtained by a well-known method. For example, it is usually used: a method including living polymerization of the monomers constituting each polymer block. As a living polymerization method, from the viewpoints of the ease of molecular weight control, composition ratio, production cost, and purity of the obtained acrylic block copolymer, anion is carried out in the presence of an organic alkali metal compound and an organic aluminum compound. The method of polymerization is preferred.

The amount of the acetone insoluble component contained in the thermoplastic resin composition of the present invention is preferably 59% by mass or less, more preferably 50% by mass or less, and still more preferably 45% by mass.

The amount of the acetone insoluble component contained in the thermoplastic resin composition is determined as follows. 2 g (w0) of the thermoplastic resin composition weighed accurately was added to 50 ml of acetone and stirred at room temperature for 24 hours. The obtained liquid was put into a centrifuge tube, and centrifugal separation was performed at 0°C and 20000 rpm for 180 minutes. Secondly, the supernatant was removed by decantation. Add acetone to the centrifuge tube and stir. Centrifugal separation was performed at 5°C and 20000 rpm for 120 minutes. Secondly, the supernatant was removed by decantation. Take out the centrifuged substance from the bottom of the centrifuge tube, dry it at 50°C under reduced pressure, and measure its mass w1. The amount (percentage) of acetone insoluble components is calculated by the formula: 100×w1/w0. The amount (percentage) of acetone soluble components is calculated by the formula: 100×(w0-w1)/w0.

The acetone-soluble component contained in the thermoplastic resin composition of the present invention can be obtained by drying the above-mentioned supernatant liquid at 50°C under reduced pressure. The acetone-soluble component is the ratio of the glass transition temperature Tg to the melt flow rate R under the conditions of 230°C and a load of 3.8 kg. Tg/R is preferably 6.0 to 1.5°C·10 min/g, more preferably 5.6 to 2.0 ℃・10min/g.

The glass transition temperature of the acetone-soluble component contained in the thermoplastic resin composition of the present invention is preferably 90-115°C, more preferably 95-110°C.

The melt flow rate R of the acetone-soluble component contained in the thermoplastic resin composition of the present invention at 230° C. and a load of 3.8 kg is preferably 15-60 g/10 min, more preferably 20-55 g/10 min.

The molding material of the present invention contains the methacrylic acid copolymer (or thermoplastic resin composition) of the present invention. The molding material of the present invention can further contain antioxidants, anti-heat degradation agents, ultraviolet absorbers, light stabilizers, lubricants, mold release agents, polymer processing aids, and anti-oxidants within a range that does not impair the effects of the present invention. Additives such as electrostatic agents, flame retardants, dyes and pigments, light diffusers, organic pigments, matting agents, impact-resistant modifiers, phosphors, etc.

Antioxidant is in the presence of oxygen, which alone has the effect of preventing oxidative degradation of the resin. For example, phosphorus antioxidants, hindered phenol antioxidants, thioether antioxidants, etc. are mentioned. Among these, from the viewpoint of the effect of preventing the deterioration of optical properties due to coloring, phosphorus antioxidants and hindered phenol antioxidants are preferred, and phosphorus antioxidants and hindered phenol antioxidants are used in combination. For better. When phosphorus antioxidants and hindered phenol antioxidants are used in combination, it is preferable to use phosphorus antioxidants/hindered phenol antioxidants in a mass ratio of 0.2/1 to 2/1, and 0.5/1 to 1/1 It is better to use.

Examples of phosphorus-based antioxidants include 2,2-methylene bis(4,6-ditributylphenyl) octyl phosphite (manufactured by ADEKA; trade name: ADK STAB HP-10), Ginseng phosphate (2,4-di-tertiary butyl phenyl) ester (manufactured by BASF; trade name: IRUGAFOS 168), 3,9-bis(2,6-di-tertiary butyl-4-methylphenoxy) Base)-2,4,8,10-tetraoxo-3,9-diphosphaspiro[5.5]undecane (manufactured by ADEKA; trade name: ADK STAB PEP-36) and the like.

As a hindered phenol-based antioxidant, pentaerythritol-tetra[3-(3,5-di-tertiarybutyl-4-hydroxyphenyl) propionate] (manufactured by BASF; trade name IRGANOX 1010), propionic acid ten Octayl-3-(3,5-di-tertiarybutyl-4-hydroxyphenyl) ester (manufactured by BASF Corporation; trade name IRGANOX 1076) and the like are preferred.

As a thermal degradation agent, it can prevent the thermal degradation of the resin by capturing polymer radicals generated when exposed to high heat in a substantially oxygen-free state. As the thermal deterioration resistance agent, acrylic acid 2-tertiary butyl-6-(3'-tertiary butyl-5'-methyl-hydroxybenzyl)-4-methylphenyl ester (manufactured by Sumitomo Chemical Co., Ltd.) ; Trade name SUMILIZER GM), 2,4-ditertiary pentyl-6-(3',5'-ditertiary pentyl-2'-hydroxy-α-methylbenzyl) phenyl acrylate (Sumitomo Chemical Company system; trade name SUMILIZER GS) etc. are preferred.

Ultraviolet absorbers are compounds that have the ability to absorb ultraviolet rays, and are mainly said to have the function of converting light energy into heat energy. Examples of ultraviolet absorbers include diphenyl ketones, benzotriazoles, triazoles, benzoates, salicates, cyanoacrylates, glycerides, and malonates. Class, formamidine, etc. Among these, benzotriazoles, triazoles, or ultraviolet absorbers having a _{maximum molar absorption coefficient ε max} ^{of 100 dm 3} ·mol ^-1 cm ^-1 or less at a wavelength of 380 to 450 nm are preferred.

Benzotriazoles have a high effect of suppressing the decrease in optical properties such as coloration caused by ultraviolet radiation, and therefore, the ultraviolet absorber used when the molded article of the present invention is applied to optical applications is preferable. As benzotriazoles, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (manufactured by BASF Corporation; trade name TINUVIN 329), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (manufactured by BASF; trade name TINUVIN 234), 2, 2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-t-octylphenol] (manufactured by ADEKA; LA-31) and the like are preferred.

_{In addition, an ultraviolet absorber having a maximum molar absorption coefficient ε max} of 1200 dm ³ ·mol ^-1 cm ^-1 or less at a wavelength of 380 to 450 nm can suppress the discoloration of the resulting molded article. As such an ultraviolet absorber, 2-ethyl-2'-ethoxy- glufosinate (made by CLARIANT JAPAN company; brand name SANDUVOR VSU) etc. are mentioned. Among these ultraviolet absorbers, benzotriazoles can be preferably used from the viewpoint of suppressing degradation of the resin due to ultraviolet irradiation.

In addition, when it is desired to efficiently absorb short wavelengths below 380 nm, it is ideal to use a triple-type ultraviolet absorber. Examples of such ultraviolet absorbers include 2,4,6-ginseng (2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-tris (manufactured by ADEKA; LA -F70), its analogs, hydroxyphenyl tris-based ultraviolet absorbers (manufactured by BASF; TINUVIN 477, TINUVIN 460) and the like.

_{In addition, the maximum value ε max} of the molar absorption coefficient of the ultraviolet absorber is measured in the following manner. 10.00 mg of ultraviolet absorber was added to 1 L of cyclohexane, and it was made to melt|dissolve so that there may be no undissolved matter by visual observation. This solution was poured into a quartz glass tank of 1 cm × 1 cm × 3 cm, and the absorbance at a wavelength of 380 to 450 nm and an optical path length of 1 cm was measured using a U-3410 spectrometer manufactured by Hitachi, Ltd. From the molecular weight (M _UV ) of the ultraviolet absorber and the maximum value (A _max ) of the measured absorbance, calculated by the following formula to calculate the maximum value of the molar absorption coefficient ε _max . ε _max ＝[A _max /(10×10 ^-3 )]×M _UV

Light stabilizers are mainly said to be compounds with the function of capturing free radicals generated by light-induced oxidation. Examples of ideal light stabilizers include hindered amines such as compounds having a 2,2,6,6-tetraalkylpiperidine skeleton.

As the lubricant, for example, stearic acid, behenic acid, stearic acid, methylene distearic acid, hydroxystearic acid triglyceride, paraffin wax, ketone wax, octanol, hardened Oil etc. If the amount of lubricant used is increased, there is a tendency to increase the melt flow rate R of the molding material of the present invention and improve the fluidity.

As a mold release agent, it is a compound having a function of facilitating separation of the molded product from the mold. Examples of mold release agents include higher alcohols such as cetyl alcohol and stearyl alcohol; glycerol higher fatty acid esters such as stearic acid monoglyceride and stearic acid diglyceride. In the present invention, as a mold release agent, it is preferable to use higher alcohols and glycerol fatty acid monoester in combination. When higher alcohols and glycerol fatty acid monoesters are used in combination, the mass ratio of higher alcohols/glycerol fatty acid monoesters is preferably used in the range of 2.5/1 to 3.5/1, in the range of 2.8/1 to 3.2/1 It is better to use.

As the polymer processing aid, for example, polymer particles having a particle diameter of 0.05 to 0.5 μm can be used. The polymer particles may be single-layer particles including polymers with a single composition ratio and a single limiting viscosity, or multilayer particles including two or more polymers with different composition ratios or limiting viscosities. Among these particles, a two-layer structure including a polymer layer with a low limiting viscosity in the inner layer and a polymer layer with a high limiting viscosity of 5 dl/g or more in the outer layer is preferable. The polymer processing aids preferably have an ultimate viscosity of 3 to 6 dl/g. Specifically, the METABLEN P series manufactured by MITSUBISHI RAYON and the PARALOID series manufactured by DOW CHEMICAL can be cited. The amount of the polymer processing aid used is preferably 0.1 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the methacrylic acid copolymer. If the use amount of the polymer processing aid is 0.1 parts by mass or more, good processing characteristics can be obtained, and if the use amount of the polymer processing aid is 5 parts by mass or less, the surface smoothness is good.

Examples of the impact-resistant modifier include: a core-shell type modifier containing acrylic rubber or diene rubber as a core layer component; a modifier containing a plurality of rubber particles, and the like. As an organic pigment, it can be ideally used: a compound that has the function of converting ultraviolet rays, which are harmful to the resin, into visible light. Examples of light diffusing agents and matting agents include glass microparticles, polysiloxane-based crosslinked microparticles, crosslinked polymer microparticles, talc, calcium carbonate, barium sulfate, and the like. As the fluorescent substance, fluorescent pigments, fluorescent dyes, fluorescent white dyes, fluorescent whitening agents, fluorescent bleaches, etc. can be cited.

These additives can be used individually by 1 type or in combination of 2 or more types. These additives can be added when the methacrylic acid copolymer is manufactured, or can be added to the manufactured methacrylic acid copolymer. From the viewpoint of suppressing the appearance defects of the molded product, the total amount of the additives contained in the methacrylic acid copolymer of the present invention is preferably 1% by mass or less, and more preferably, relative to the methacrylic acid copolymer resin. 0.8% by mass or less, more preferably 0.5% by mass or less.

The methacrylic acid copolymer or thermoplastic resin composition of the present invention can be used as a molding material in any form such as pellets, granules, powders, etc., in order to improve the convenience of transportation and storage.

The molded article of the present invention can be obtained by molding the methacrylic acid copolymer (or thermoplastic resin composition or molding material) of the present invention. The molding can be performed by a well-known method such as an injection molding method, a compression molding method, an extrusion molding method, a vacuum molding method, and a casting molding method. Among these, the injection molding method is preferred. The methacrylic acid copolymer of the present invention can provide a thin and wide-area molded product with little residual warpage and almost no coloring with high production efficiency even in the case of injection molding with a high injection pressure at a low cylinder temperature. The maximum value of the ratio of the resin flow length to the thickness of the mold that can be used for injection molding of the methacrylic acid copolymer of the present invention is preferably 450 or more. If the maximum value of the ratio of the resin flow length to the thickness is as large as described above, the methacrylic acid copolymer of the present invention is suitable for producing thin molded products. The molded product of the ideal form of the present invention is a plate shape, and its thickness is preferably 0.5 mm or less, more preferably 0.45 mm or less, still more preferably 0.4 mm or less, and still more preferably 0.35 mm or less.

The methacrylic acid copolymer (or thermoplastic resin composition or molding material) of the present invention is suitable for manufacturing the housing of a mobile phone terminal. A mobile phone terminal is a terminal used in a telephone service (ie, a mobile phone) that can talk while moving. The mobile phone terminal at least includes: an antenna, a speaker, a microphone, an input/output device, a display device, an electronic circuit and a power supply, and a housing for accommodating these. Mobile phone terminals are highly required to be miniaturized and lightweight. Therefore, the casing for mobile phone terminals is required to be thinner to ensure a practical level of strength.

The methacrylic copolymer (or thermoplastic resin composition or molding material) of the present invention can ensure a practical level of strength even if it is thinned. The housing for the mobile phone terminal of the present invention is formed by containing the methacrylic acid copolymer (or thermoplastic resin composition or molding material) of the present invention, for example, the thickness is preferably 0.8 mm or less, more preferably 0.7 mm or less, and more preferably The part of 0.6 mm or less contains the methacrylic acid copolymer (or thermoplastic resin composition or molding material) of this invention.

Examples of the molded article of the present invention include: advertising towers, advertising stand, side-hung signboards, frontal signboards, roof signboards, and other signboard parts; display cabinets, partitions, shop displays, and other display parts; fluorescent lamp covers (covers) , Atmosphere lighting lampshades, lamp shades, luminous ceilings, light walls, chandeliers and other lighting parts; chandeliers, mirrors and other interior decoration parts; doors, domes, safety windows, partitions, stair guards, balconies Architectural parts such as guards, roofs of recreational buildings; aircraft windshields, pilot sun visors, locomotives, motor boats windshields, bus sun visors, automobile side sun visors, rear sun visors, front wings, Transporter-related parts such as headlights and lampshades; audio and video nameplates, stereo nets, TV protection covers, vending machines and other electronic equipment parts; incubators, X-ray imaging parts and other medical equipment parts; mechanical covers, measuring instrument covers, experiments Device, ruler, dial, observation window and other machine-related parts; LCD protection plate, light guide plate, light guide film, Fresnel lens, cylindrical lens, various display front panels, diffuser, polarizer protective film, polarizer protection Optical-related parts such as films, retardation films, and mobile phone housings; traffic-related parts such as road signs, indicator boards, curve mirrors, soundproof walls, etc.; surface materials for automobile interiors, surface materials for mobile phones, marking films, etc. Film components; components used in household appliances such as the top cover of washing machine, control panel, and top panel of cooking utensils; in addition, examples include greenhouses, large sinks, tank sinks, clock panels, bathtubs, bathroom equipment, desk mats, entertainment machines Parts, toys, face protection masks during welding, etc. Among these, the methacrylic copolymer of the present invention is suitable for optical components, and among the optical components, it is suitable for light guides and housings for mobile phones.

The light guide is used, for example, as a member of the backlight of the liquid crystal display element. It is the one that guides the light from the light source on the side or the back and can radiate light uniformly from the entire panel. Sometimes micron-sized irregularities are provided on the surface of the light guide to uniformly radiate light. If the methacrylic acid copolymer of the present invention is used, a thin (0.5 mm or less) and wide-area light guide can be obtained. In addition, if the methacrylic acid copolymer of the present invention is used, the micron-sized irregularities engraved on the mold stamper can be faithfully reproduced on the surface of the molded article.

Examples are shown below to explain the present invention more specifically. In addition, the present invention is not limited by the embodiment.

Examples 1 to 7 and Comparative Examples 1 to 4 In the sterilizer equipped with a mixer, put in refined methyl methacrylate (MMA), methyl acrylate (MA), and 2,2'-azobis(2-methylpropionitrile) in the proportions listed in Table 1. ) (AIBN) and n-octyl mercaptan (n-OM), uniformly dissolve them to obtain polymerization raw materials. The polymerization raw materials were continuously supplied from the sterilizer at 1.5 kg/hr to a tank reactor whose temperature was controlled at 140°C, and the polymerization reaction was carried out by the block polymerization method with an average residence time of 120 minutes. From the tank reactor The liquid containing the methacrylic acid copolymer is continuously discharged. The polymerization conversion rate was 57% by mass. Next, the liquid discharged from the reactor was heated to 230°C and supplied to a twin-shaft extruder controlled at 240°C. In this biaxial extruder, the volatile components mainly composed of unreacted monomers are separated and removed, and the methacrylic acid copolymer is extruded as strands. The strand was cut with a pelletizer to obtain a pellet-like methacrylic acid copolymer.

The measurement of the physical properties of the methacrylic acid copolymer is performed by the following method. The results are shown in Table 1. In addition, in the present example and the comparative example, the amount of the MMA-derived unit is the amount of the unit other than the MA unit, so the description in the table is omitted.

(Proportion of units derived from methyl acrylate (MA units)) Dissolve 1 g of resin particles in 40 ml of dichloromethane. Take 25 μl of the resulting solution to a platinum plate. Removal of methylene chloride is based on the use of a pyrolysis gas chromatograph (GC-14A manufactured by Shimadzu Corporation, thermal decomposition furnace temperature: 500°C, column: SGE BPX-5, temperature conditions: maintaining at 40°C for 5 minutes → Calculate the ratio of MA units with the recorded chromatograms at 5°C/min (up to 280°C).

(Polymerization conversion rate, residual volatile components) Gas chromatograph GC-14A manufactured by Shimadzu Corporation was connected to INERTCAP 1 manufactured by GL Sciences Inc. (df=0.4μm, 0.25mmI.D.×60m) as a column, and the analysis was performed under the following conditions. Figure out. Injection temperature = 250℃ Detector temperature = 250℃ Temperature conditions: maintain at 60°C for 5 minutes → increase temperature at 10°C/min to 250°C → maintain at 250°C for 10 minutes

(Molecular weight distribution Mw/Mn) From the chromatogram measured by GPC (Gel Permeation Chromatography), the value corresponding to the molecular weight of standard polystyrene was used as the molecular weight of the copolymer. Device: GPC device HLC-8320 manufactured by TOSOH Separation column: TSKguardcolum SuperHZ-H, TSKgel HZM-M and TSKgel SuperHZ4000 manufactured by TOSOH are connected in series Eluent: Tetrahydrofuran Eluent flow rate: 0.35ml/min Column temperature: 40℃ Detection method: Differential refractive index (RI)

(The amount of bonded sulfur atoms (bonded S)) The amount of bonded sulfur atoms of the methacrylic acid copolymer is a value determined in the following manner. The methacrylic acid copolymer was dissolved in chloroform to obtain a solution. This solution was added to n-hexane to obtain a precipitate. The precipitate was dried under vacuum at 80°C for more than 12 hours. The obtained dried product is accurately weighed and installed in a sulfur combustion device, decomposed by a reaction furnace at a temperature of 400°C, and the generated gas is passed through a furnace at a temperature of 900°C, followed by absorption with 0.3% hydrogen peroxide water. The obtained liquid (decomposition gas aqueous solution) is appropriately diluted with pure water, and sulfuric acid ions are quantified by ion chromatography (ICS-1500 manufactured by DIONEX, column: AS12A). _{Calculate the mass W p} (mass %) of sulfur atoms per mass of the dried product. Using the mass of the structural unit derived from methyl methacrylate relative to the methacrylic acid copolymer W _MMA (mass%), the following formula is used to calculate the bond relative to the structural unit derived from methyl methacrylate The amount of sulfur atoms S _p (mol %). S _p ＝W _p ×(100/32)/(W _MMA /100)

2 g of the test sample was put into 50 mL of acetone and stirred at room temperature for 24 hours. The whole amount of the obtained liquid was centrifuged using a centrifuge (manufactured by Hitachi Koki Co., Ltd., CR20GIII) under the conditions of a rotation speed of 20000 rpm, a temperature of 0°C, and 180 minutes. The supernatant liquid and the precipitate were respectively collected and dried at 50°C under vacuum for 8 hours to obtain the acetone insoluble component (A) and the acetone soluble component (B).

(Melt flow rate R) According to JIS K7210, it is measured under the conditions of 230°C, 3.8 kg load, and 10 minutes.

(Glass transition temperature Tg) The acetone insoluble components of the methacrylic acid copolymer and the thermoplastic resin obtained in the examples were heated to 250°C at one degree using a differential scanning calorimetry device (made by Shimadzu Corporation, DSC-50 (model)) in accordance with JIS K7121. After cooling to room temperature, the DSC curve was measured under the condition of heating from room temperature to 200°C at 10°C/min. The glass transition temperature at the intermediate point obtained from the DSC curve measured during the second heating is used as the glass transition temperature in the present invention.

(Bending strength) The bending strength of the methacrylic acid copolymer obtained in the examples and comparative examples. Using this test piece, it measured in accordance with JIS K7171 with a test piece thickness of 4 mm.

(Injection moldability) Using an injection molding machine (manufactured by Sumitomo Heavy Industries Co., Ltd.: SE-180DU-HP), injection molding is performed at a cylinder temperature of 280°C, a mold temperature of 75°C, and a molding cycle of 1 minute. The long side is 205mm, the short side is 160mm, and the thickness is 0.4mm flat S. The ratio of the resin flow length to the thickness of the plate S from the die inlet is 475 (=190mm/0.4mm). The appearance of the plate S was observed and evaluated by the following indexes. A: There are no cracks or sink marks. B: There are sink marks. C: Cracked.

(Mold contamination) Using the "M-100C" injection molding machine made by Meiki Seisakusho, using a flat mold (molded product size: 40mm×200mm×2mm) at a molding temperature of 260°C, a mold temperature of 60°C, a molding cycle of 26 seconds, and no holding pressure Under the condition of (short shot), 40 shots are used for injection molding. Investigate the contamination of the mold surface and evaluate it with the following indicators. A: No mold contamination. C: Mold contamination.

(fluidity) In the SE-180DU-HP molding machine manufactured by Sumitomo Heavy Industries, under the conditions of a mold temperature of 50°C, a molding temperature of 300°C, an injection speed of 100mm/sec, and a filling pressure of 150MPa, in a swirl mold (product thickness 0.4mm, width 10mm) for injection molding. Measure the swirl flow length at this time, and evaluate the fluidity using the following indicators. A: Above 125mm B: 115mm above and less than 125mm C: less than 115mm

Table 1 Example 1 2 3 4 Polymerization raw materials MMA[pts.] 91.8 90.4 88.0 85.5 MA[pts.] 8.2 9.6 12.0 14.5 n-0M[pts.] 0.47 0.47 0.46 0.44 AIBN[pts.] 0.007 0.007 0.007 0.007 Methacrylic acid copolymer (1) (2) (3) (4) Monomer unit composition MA unit [%] 6.5 7.9 9.3 11.1 Mw 49k 50k 51k 53k Mw/Mn 2.0 2.0 2.0 2.0 The amount of bonding S [mol%] 0.33 0.33 0.33 0.33 R[g/10min] 35 41 49 58 Tg[℃] 106 103 99 96 Tg/R[℃･10min/g] 3.0 2.5 2.0 1.7 Flexural strength [MPa] 60 65 65 70 Injection moldability A A A A Mold contamination A A A A fluidity A A A A

Table 1 (continued from above) Example 5 6 7 Polymerization raw materials MMA[pts.] 94.2 92.0 94.2 MA[pts.] 5.8 8.0 5.8 n-0M[pts.] 0.43 0.45 0.47 AIBN[pts.] 0.007 0.007 0.007 Methacrylic acid copolymer (5) (6) (7) Monomer unit composition MA unit [%] 5.0 6.0 4.9 Mw 55k 52k 49k Mw/Mn 1.8 1.8 2.0 The amount of bonding S [mol%] 0.30 0.31 0.32 R[g/10min] twenty two 30 29 Tg[℃] 108 104 106 Tg/R[℃･10min/g] 4.9 3.4 3.6 Flexural strength [MPa] 80 68 60 Injection moldability A A A Mold contamination A A A fluidity B B B

Table 1 (continued from above) Comparative example 1 2 3 4 Polymerization raw materials MMA[pts.] 90.5 91.8 80.0 94.0 MA[pts.] 9.5 8.2 20.0 6.0 n-0M[pts.] 0.39 0.53 0.43 0.34 AIBN[pts.] 0.007 0.007 0.007 0.007 Methacrylic acid copolymer (8) (9) (10) (11) Monomer unit composition MA unit [%] 7.7 6.5 16.0 4.5 Mw 60k 45k 55k 64k Mw/Mn 1.9 1.9 1.9 1.8 The amount of bonding S [mol%] 0.29 0.35 0.34 0.34 R[g/10min] 20 40 65 10 Tg[℃] 103 106 88 11 Tg/R[℃･10min/g] 5.2 2.7 1.4 1.1 Flexural strength [MPa] 125 55 85 100 Injection moldability B C B A Mold contamination A C C A fluidity C A A C

As shown by the above results, the methacrylic copolymer of the present invention has high fluidity, excellent injection moldability, and is less likely to cause mold contamination.

Production example 1 (acrylic rubber particles) Into a reactor equipped with a stirrer, a thermometer, a nitrogen introduction tube, a monomer introduction tube and a reflux condenser, put 1050 parts by mass of ion exchange water, 0.44 parts by mass of polyoxyethylene tridecyl ether sodium acetate and 0.7 parts by mass of sodium carbonate. The inside of the vessel is replaced with nitrogen. Next, the internal temperature was set to 80°C. 0.25 parts by mass of potassium persulfate was added thereto, and stirred for 5 minutes. To this, 245 parts by mass of a monomer mixture containing 95.4% by mass of methyl methacrylate, 4.4% by mass of methyl acrylate, and 0.2% by mass of allyl methacrylate were continuously dropped into it for 60 minutes. After the dripping, the polymerization reaction was further performed for 30 minutes so that the polymerization conversion rate became 98% or more. Next, in the same reactor, 0.32 parts by mass of potassium persulfate was added and stirred for 5 minutes. After that, 315 parts by mass of a monomer mixture containing 80.5% by mass of butyl acrylate, 17.5% by mass of styrene, and 2% by mass of allyl methacrylate were dropped continuously over 60 minutes. After the dripping, the polymerization reaction was further performed for 30 minutes so that the polymerization conversion rate became 98% or more. Next, in the same reactor, 0.14 parts by mass of potassium persulfate was added and stirred for 5 minutes. After that, 140 parts by mass of a monomer mixture containing 95.2% by mass of methyl methacrylate, 4.4% by mass of methyl acrylate, and 0.4% by mass of n-octyl mercaptan was continuously dropped in 30 minutes. After the dripping, the polymerization reaction was further performed for 60 minutes so that the polymerization conversion rate became 98% or more. Through the above operations, a latex containing acrylic rubber particles is obtained. The latex is frozen and solidified. Next, water washing and drying are performed to obtain acrylic rubber particles. The average particle size of the acrylic rubber particles is 0.2 μm.

Production Example 2 (Acrylic Block Copolymer) According to the usual method, it contains [methyl methacrylate (MMA) polymer block (b1-1)]-[n-butyl acrylate (BA) polymer block (b2)]-[methyl methacrylate (MMA) polymer block (b1-2)], the weight average molecular weight (Mw) is 65,000, and the total mass ratio of the polymer block (b1-1): (c2): (b1-2) is 15:70 : 15, the mass ratio of each monomer (MMA: BA) = (30: 70) triblock copolymer.

Examples 8-13 and Comparative Examples 5-7 The methacrylic copolymer, acrylic rubber particles, and acrylic block copolymer were mixed in the proportions described in Table 2, and they were melt-kneaded and extruded at 250°C using a biaxial extruder with a shaft diameter of 20 mm. Thermoplastic resin composition.

The measurement of the physical properties of the thermoplastic resin composition and the like is carried out by the following method. The results are shown in Table 2.

(Transparency) Using an injection molding machine (manufactured by Meiji Seisakusho Co., Ltd., M-100C), the thermoplastic resin compositions obtained in the examples and comparative examples were combined under the conditions of a cylinder temperature of 260°C, a mold temperature of 50°C, and an injection speed of 50 mm/sec. By injection molding, a square injection molded sheet with a thickness of 3 mm and a side of 50 mm was obtained. The total light transmittance Tt and the haze H of each test piece were measured using a spectrophotometer SE5000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with the method described in JIS K7361-1, and evaluated using the following indexes. A: Tt is 90% or more and H is 5% or less B: Tt is 80% or more and less than 90% or H is 10% or less C: Tt is less than 80% or H is greater than 10%

(Surface hardness) Using an injection molding machine (manufactured by Meiji Seisakusho Co., Ltd., M-100C), the thermoplastic resin compositions obtained in the examples and comparative examples were combined under the conditions of a cylinder temperature of 260°C, a mold temperature of 50°C, and an injection speed of 50 mm/sec. By injection molding, a square injection molded sheet with a thickness of 3 mm and a side of 50 mm was obtained. Using a desk-moving pencil scratch tester (model P) (manufactured by Toyo Seiki Co., Ltd.), confirm while pressing the pencil lead at an angle of 45 degrees and a load of 750 g on the surface of the thermoplastic resin composition side of the injection molded sheet. Whether there are scratches or scratches. The hardness of the pencil core increases sequentially, and the hardness of the core that is softer than the time point when the scar is generated is regarded as the pencil hardness, and the obtained pencil hardness is evaluated by the following index. A: Pencil hardness is 2H or more B: Pencil hardness is more than F and less than 2H C: Pencil hardness is less than F

(Impact resistance) Using an injection molding machine (M-100C manufactured by Meiji Seisakusho Co., Ltd.), the examples and comparative examples were obtained under the conditions of a cylinder temperature of 260°C, a mold temperature of 50°C, and an injection speed of 50mm/sec. The thermoplastic resin composition was injection molded to obtain a long injection molded sheet with a thickness of 4 mm, a long side of 80 mm, and a short side of 10 mm. Each test piece was subjected to a Charpy impact test according to the method described in ISO179-1, and the measurement was carried out. The flatwise method and the Charpy impact strength without dents were used as the Charpy impact strength, and the obtained Charpy impact strength was evaluated by the following index. A: Charpy impact strength of 60kJ / m ² or more B: Charpy impact strength of 40kJ / m ² or more is less than 60kJ / m ² C: Charpy impact strength is less than 40kJ / m ²

(fluidity) Using an injection molding machine (manufactured by Meiji Seisakusho Co., Ltd., M-100C), under the conditions of a mold temperature of 50°C, a molding temperature of 250°C, an injection speed of 100mm/sec, and a filling pressure of 100MPa, in a swirl mold (product thickness 1mm, width 10mm) for injection molding. Measure the swirl flow length at this time, and evaluate the fluidity using the following indicators. A: Swirl length is more than 350mm B: Swirl length is more than 300mm and less than 350mm C: Swirl length is less than 300mm

Table 2 Example Comparative example 8 9 10 11 12 13 5 6 7 Resin composition [pts.] Methacrylic acid copolymer (4) 35 55 30 Methacrylic acid copolymer (2) 14 Methacrylic acid copolymer (5) 70 twenty one 15 63 20 30 60 14 Methacrylic acid copolymer (10) 28 20 58 40 Acrylic rubber particles 30 44 30 27 40 28 20 28 60 Acrylic block copolymer 10 10 Physical properties Acetone insoluble ingredients content[%] 29 42 29 26 38 27 19 27 57 Acetone soluble ingredients content[%] 71 58 71 74 62 73 81 73 43 Tg[℃] 108 101 99 109 104 104 110 111 110 R[g/10min] twenty two 44 50 20 37 32 11 10 11 Tg/R 4.9 2.3 2.0 5.6 2.8 3.2 10.5 10.2 10.2 Molded product Tt[%] 92 91 91 87 84 92 92 92 92 H[%] 2.8 3.6 2.8 6.3 8.2 3.4 2.1 3.2 1.8 Transparency A A A B B A A A A Pencil hardness 2H F H H F 2H 2H 2H F Surface hardness A B B B B A A A B Charpy impact strength [kJ/m ² ] 52 77 40 73 102 56 35 62 98 Impact resistance B A B A A B C A A Swirl length [mm] 330 310 365 350 335 325 345 295 270 fluidity B B A A B B B C C

As shown by the above results, the thermoplastic resin composition of the present invention can provide a thin molded body excellent in transparency, surface hardness, and impact resistance.

no.

no.

no.

Claims (13)

A methacrylic acid copolymer comprising 85.0-95.0% by mass of monomer units derived from methyl methacrylate and 5.0-15.0% by mass of monomer units derived from acrylate, The weight average molecular weight Mw is 48000～59000, The ratio Mw/Mn of the weight average molecular weight Mw to the number average molecular weight Mn is 2.1 or less, and The ratio Tg/R of the glass transition temperature Tg to the melt flow rate R under the conditions of 230°C and a load of 3.8 kg is 5.0 to 1.5°C·10 min/g. The methacrylic acid copolymer of claim 1, wherein the amount of bonded sulfur atoms relative to the monomer unit derived from methyl methacrylate is 0.4 mol% or less, and the melt flow rate R is 25 g/10 Points or more. A thermoplastic resin composition containing the methacrylic acid copolymer of claim 1 and acrylic rubber particles. Such as the thermoplastic resin composition of claim 3, which further contains an acrylic block copolymer. The thermoplastic resin composition of claim 3 or 4, wherein the acetone-insoluble component contained in the thermoplastic resin composition is 59% by mass or less, and The acetone-soluble component contained in the thermoplastic resin composition has a ratio Tg/R of the glass transition temperature Tg to the melt flow rate R under the conditions of 230°C and a 3.8 kg load of 6.0 to 1.5°C·10 min/g. A pellet-shaped molding material comprising the methacrylic acid copolymer as claimed in claim 1 or 2. A molded product containing the methacrylic acid copolymer as claimed in claim 1 or 2. Such as the molded product of claim 7, which is a plate with a thickness of 0.5 mm or less. A housing for a mobile phone terminal, which contains the methacrylic acid copolymer as claimed in claim 1 or 2. A housing for a mobile phone terminal, which has a part with a thickness of 0.8 mm or less containing the methacrylic acid copolymer of claim 1 or 2. An optical member containing the methacrylic acid copolymer as claimed in claim 1 or 2. A method for producing a methacrylic acid copolymer, which is the method for producing a methacrylic acid copolymer according to claim 1 or 2, which comprises: polymerizing monomers containing methyl methacrylate and acrylate by a bulk polymerization method Carry out the polymerization reaction. A method of manufacturing a methacrylic acid copolymer, which comprises: 100 parts by mass of monomers containing at least 81.0-94.2% by mass of methyl methacrylate and 5.8-19.0% by mass of acrylate, 0.42 to 0.52 parts by mass of chain transfer agent, and polymerization initiator with an average residence time of 1.5-3 hours It is supplied to a continuous flow-through reactor without using a solvent at a temperature of 110-140°C, and polymerized at a polymerization conversion rate of 35-65%, Secondly, heating at 220～260℃ to remove unreacted monomers; The methacrylic acid copolymer series: containing 85-95.0% by mass of structural units derived from methyl methacrylate and 5.0-15.0% by mass of structural units derived from acrylate, The weight average molecular weight Mw is 48000～59000, The ratio Mw/Mn of the weight average molecular weight Mw to the number average molecular weight Mn is 2.1 or less, and A methacrylic acid copolymer whose glass transition temperature Tg is a methacrylic acid copolymer whose ratio Tg/R to the melt flow rate R under the conditions of 230°C and a load of 3.8 kg is 5.0 to 1.5°C·10 min/g.