JP2020012072A - Methacrylic resin and molding thereof - Google Patents

Abstract

To provide a methacrylic resin having excellent flowability, and excellent heat resistance and surface hardness.SOLUTION: A methacrylic resin has a repeating unit derived from methyl methacrylate of 98.0 mass% or more and 99.9 mass% or less and a repeating unit derived from a monomer excluding methyl methacrylate of 0.1 mass% or more and 2.0 mass% or less. The proportion of a molecular weight component of 1/5 or less of a peak molecular weight obtained from an elution curve by gel permeation chromatography is less than 7%.SELECTED DRAWING: None

Description

The present invention relates to a methacrylic resin and a molded article thereof.

  In general, methyl methacrylate-based methacrylic resins are used, for example, for tail lamp covers, head lamp covers, and instrument panel covers, especially for automotive applications, such as tail lamp covers, due to their excellent weather resistance and excellent transparency. It is used in various fields such as members (hereinafter, referred to as “vehicle members”), signboards, ornaments, and miscellaneous goods.

  In recent years, there has been an increasing demand for vehicle members to be thinner and larger to improve fuel efficiency, and methacrylic resins are required to have excellent fluidity.

As a technique for improving the fluidity of a methacrylic resin, Patent Literatures 1 to 3 disclose a methacrylic resin containing a high molecular weight substance and a low molecular weight substance.
Patent Literature 4 proposes a methacrylic resin plate having excellent transparency, particularly excellent ultraviolet transmittance.
Patent Documents 5 to 7 propose a thermoplastic resin composition and a molded article containing a surface hardness improver composed of a methyl methacrylate resin.

Patent No. 5395027 WO2017 / 010323 WO2015 / 199038 JP 2017-87664 A JP-A-2006-0440387 JP 2014-111799 A JP 2010-116501 A

  However, the methacrylic resins proposed in Patent Literatures 1 to 3 describe physical properties such as fluidity, solvent resistance, and bending strength, but none of them describe surface hardness. Patent Document 4 does not describe the surface hardness of a methacrylic resin plate. Patent Documents 5 to 7 describe that a methacrylate-based copolymer having a specific mass average molecular weight is useful as a surface hardness improver, but there is no description on its fluidity and heat resistance.

  Therefore, an object of the present invention is to provide a methacrylic resin having excellent fluidity, excellent heat resistance, and excellent surface hardness.

  According to the present invention, the above object is achieved by the following aspects.

[1] containing 98.0% by mass or more and 99.9% by mass or less of a repeating unit derived from methyl methacrylate, and 0.1% by mass or more and 2.0% by mass or less of a repeating unit derived from a monomer other than methyl methacrylate; A methacrylic resin in which the ratio of a molecular weight component having 1/5 or less of a peak molecular weight obtained from an elution curve by gel permeation chromatography is less than 7%.
[2] The methacrylic resin is obtained by mixing two or more polymers having different peak molecular weights, and the polymer having the highest molecular weight has a peak molecular weight of 110,000 or more and less than 180,000; The methacrylic resin according to [1], wherein the polymer has at least one polymer having a peak molecular weight of 36,000 or more and less than 110,000 and a repeating unit derived from methyl methacrylate of 99.9% by mass or more.
[3] The methacrylic resin according to [1] or [2], comprising a polymer containing 99.9% by mass or more of a repeating unit derived from methyl methacrylate by 60% to 90% by mass.
[4] The methacrylic resin according to any one of [1] to [3], which is used for injection molding.
[5] The methacrylic resin according to any one of [1] to [4], which is used for a vehicle.
[6] A molded article obtained from the methacrylic resin according to any one of [1] to [5].

  The methacrylic resin of the present invention has excellent fluidity, heat resistance and surface hardness.

FIG. 2 is a diagram derived from an elution curve of the methacrylic resin produced in Example 1 by gel permeation chromatography. The vertical axis indicates the RI detection intensity, and the horizontal axis indicates the logarithm of the molecular weight (M).

(Methacrylic resin)
In the methacrylic resin of the present invention, the total content of repeating units derived from methyl methacrylate is preferably from 98.0% by mass to 99.9% by mass, more preferably from 98.5% by mass to 99.9% by mass, Most preferably, it is 99.0% by mass or more and 99.9% by mass or less.
In order to improve the processing fluidity during molding of the methacrylic resin, and to obtain good heat resistance and surface hardness of the molded article, the amount of the molecular weight component which is 1/5 or less of the peak molecular weight (Mp) of the methacrylic resin is required. Preferably it is less than 7%.
In addition, the abundance of the molecular weight component of 1/5 or less of the peak molecular weight (Mp) is determined by the ratio of the area obtained from the GPC elution curve.
When a plurality of peaks are present in the GPC elution curve, the peak indicates the peak indicated by the molecular weight having the highest abundance.
When the total content of the repeating units derived from methyl methacrylate in the methacrylic resin is 98.0% or more, and the abundance of the molecular weight component of 1/5 or less of the peak molecular weight (Mp) of the methacrylic resin is less than 7%. If so, the methacrylic resin is excellent in heat resistance and surface hardness.

Examples of monomers other than methyl methacrylate include methacrylates, acrylates, and non-ester vinyl monomers having only one polymerizable carbon-carbon double bond in one molecule.
Examples of the methacrylate include alkyl methacrylates other than methyl methacrylate such as ethyl methacrylate and butyl methacrylate; aryl methacrylates such as phenyl methacrylate; cycloalkyl methacrylates such as cyclohexyl methacrylate and norbornenyl methacrylate.
Examples of the acrylate include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate and 2-ethylhexyl acrylate; aryl acrylates such as phenyl acrylate; cycloalkyl acrylates such as cyclohexyl acrylate and norbornenyl acrylate And the like. Of these, methyl acrylate is preferred.
Non-ester vinyl monomers having only one polymerizable carbon-carbon double bond in one molecule include aromatic vinyl compounds such as styrene and α-methylstyrene; acrylamide; methacrylamide; acrylonitrile; Nitrile; and the like.
The methacrylic resin of the present invention may be composed of only one kind of polymer, but is preferably a composition containing two or more kinds of polymers, and more preferably each polymer has a different peak molecular weight.

  The methacrylic resin has a molecular weight Mp (also referred to as a peak molecular weight) in terms of polymethyl methacrylate corresponding to a retention time showing a maximum intensity value in a chromatogram obtained by gel permeation chromatography, and is preferably 30,000 or more and 100,000 or less. , More preferably 40,000 or more and 95,000 or less, still more preferably 50,000 or more and 90,000 or less.

The measurement by gel permeation chromatography can be performed as follows. As an eluent, tetrahydrofuran is used, and as a column, two TSKgelSuperMultipore HZM-M manufactured by Tosoh Corporation and SuperHZ4000 are used in series. As an analyzer, HLC-8320 (product number) manufactured by Tosoh Corporation equipped with a differential refractive index detector (RI detector) is used. A test target solution is prepared by dissolving a resin material to be tested, that is, methacrylic resin or 4 mg of methacrylic resin in 5 ml of tetrahydrofuran and further filtering through a 0.1 μm filter. The temperature of the column oven is set at 40 ° C., and 20 μl of the solution to be tested is injected at an eluent flow rate of 0.35 ml / min, and the chromatogram is measured.
The chromatogram is a chart in which the electric signal value (intensity Y) derived from the difference in the refractive index between the solution to be tested and the reference solution is plotted against the retention time X.

  A standard polymethyl methacrylate having a molecular weight in the range of 1,000 to 2,200,000 was measured by gel permeation chromatography, and a calibration curve showing the relationship between retention time and molecular weight was created. The line connecting the point where the slope on the high molecular weight side of the chromatogram changes from zero to plus and the point where the slope of the peak on the low molecular weight side changes from minus to zero was defined as the baseline. If the chromatogram shows multiple peaks, draw a line connecting the point where the slope of the peak with the highest molecular weight changes from zero to plus and the point where the slope of the peak with the lowest molecular weight changes from minus to zero. The baseline was set.

  The methacrylic resin of the present invention may contain two or more polymers having different peak molecular weights, preferably two to four polymers, and more preferably three polymers. The peak molecular weight (Mpa) of the polymer [a] on the highest molecular weight side is 110,000 or more and less than 180,000, and the peak molecular weight (Mpb) of the polymer [b] on the lowest molecular weight side is 36,000 or more and less than 110,000. Preferably, there is.

The methacrylic resin of the present invention has better fluidity and heat resistance when it contains three kinds of polymers having mutually different peak molecular weights. The highest molecular weight polymer [a] has a peak molecular weight (Mpa) of 110,000 or more and less than 180,000, and the intermediate molecular weight polymer [c] has a peak molecular weight (Mpc) of 65,000 or more and less than 110,000. The peak molecular weight (Mpb) of the polymer [b] on the low molecular weight side is preferably 36,000 or more and less than 65,000. Each polymer contained in the methacrylic resin contains a repeating unit derived from methyl methacrylate.
In one preferred embodiment, the methacrylic resin of the present invention mixed with polymers having different peak molecular weights has a single peak molecular weight.

  It is preferable that at least one polymer contained in the methacrylic resin of the present invention contains 99.9% by mass or more of a repeating unit derived from methyl methacrylate.

  In order for the methacrylic resin of the present invention to have excellent heat resistance and surface hardness, the content of the methacrylic resin containing 99.9% by mass or more of the repeating unit derived from methyl methacrylate should be 60% by mass or more and 90% by mass or less. Preferably, it is 70% by mass or more and 87% by mass or less, more preferably 75% by mass or more and 85% by mass or less.

  In order for the methacrylic resin of the present invention to have excellent fluidity, heat resistance and surface hardness, the polymer containing 99.9% by mass or more of a repeating unit derived from methyl methacrylate is a polymer [c] having an intermediate molecular weight. Is most preferred.

  The methacrylic resin of the present invention may be prepared by individually polymerizing two or more types of polymers having mutually different peak molecular weights, and then kneading the two or more types of polymers in an extruder.

  Further, using a multi-stage polymerization, for example, after polymerizing a monomer component capable of forming another polymer in the presence of a composition (syrup) containing one polymer, the syrup is kneaded in an extruder. You may.

  Each polymer contained in the methacrylic resin may be obtained by any manufacturing method, from the viewpoint of productivity, in the radical polymerization method, polymerization temperature, polymerization time, the type and amount of the chain transfer agent, Those produced by adjusting the type and amount of the polymerization initiator are preferred. Examples thereof include an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, and a solution polymerization method.

  The polymerization initiator used in the radical polymerization method for producing each polymer contained in the methacrylic resin is not particularly limited as long as it generates a reactive radical. For example, t-hexylperoxyisopropyl monocarbonate, t-hexylperoxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, t-butylperoxypivalate , T-hexyl peroxypivalate, t-butyl peroxy neodecanoate, t-hexyl peroxy neodecanoate, 1,1,3,3-tetramethylbutyl peroxy neodecanoate, 1,1 -Bis (t-hexylperoxy) cyclohexane, benzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, lauroyl peroxide, 2,2'-azobis (2-methylpropionitrile), 2,2 ' -Azobis (2-methylbutyronitrile), dimethyl 2,2'-azobis (2 -Methylpropionate) and the like. Of these, t-hexylperoxy 2-ethylhexanoate, 1,1-bis (t-hexylperoxy) cyclohexane, and dimethyl 2,2'-azobis (2-methylpropionate) are preferred.

  The one-hour half-life temperature of such a polymerization initiator is preferably from 60 to 140 ° C, more preferably from 80 to 120 ° C. Further, the polymerization initiator used for the production of each polymer contained in the methacrylic resin has a hydrogen abstracting ability of preferably 20% or less, more preferably 10% or less, and further preferably 5% or less. Such polymerization initiators can be used alone or in combination of two or more. The amount of the polymerization initiator to be used is preferably 0.0001 to 0.02 parts by mass, more preferably 0.001 to 0.01 parts by mass, and still more preferably 100 parts by mass of the monomer subjected to the polymerization reaction. Is 0.005 to 0.007 parts by mass.

  In addition, the hydrogen abstraction ability can be known from the technical data of the polymerization initiator manufacturer (for example, Nippon Oil & Fats Co., Ltd. technical data "Hydrogen abstraction ability and initiator efficiency of organic peroxide" (prepared in April, 2003)). . Further, it can be measured by a radical trapping method using an α-methylstyrene dimer, that is, an α-methylstyrene dimer trapping method. The measurement is generally performed as follows. First, a polymerization initiator is cleaved in the presence of α-methylstyrene dimer as a radical trapping agent to generate radical fragments. Among the generated radical fragments, those having low hydrogen abstracting ability are trapped by adding to the double bond of α-methylstyrene dimer. On the other hand, a radical fragment having a high hydrogen abstracting ability abstracts hydrogen from cyclohexane to generate a cyclohexyl radical, and the cyclohexyl radical is added to the double bond of the α-methylstyrene dimer and trapped to generate a cyclohexane trapped product. Therefore, the ratio (molar fraction) of a radical fragment having a high hydrogen abstraction ability to the theoretical radical fragment generation amount, which is determined by quantifying cyclohexane or a cyclohexane capture product, is defined as the hydrogen abstraction ability.

  As the chain transfer agent used in the radical polymerization method for producing each polymer contained in the methacrylic resin, n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, 1,4-butanedithiol, 1,6- Hexanedithiol, ethylene glycol bisthiopropionate, butanediol bisthioglycolate, butanediol bisthiopropionate, hexanediol bisthioglycolate, hexanediol bisthiopropionate, trimethylolpropane tris- (β-thio Alkyl mercaptans such as propionate) and pentaerythritol tetrakisthiopropionate. Of these, monofunctional alkyl mercaptans such as n-octyl mercaptan and n-dodecyl mercaptan are preferred. One of these chain transfer agents can be used alone, or two or more can be used in combination.

  The amount of the chain transfer agent to be used is preferably 0.1 to 1 part by mass, more preferably 0.15 to 0.8 part by mass, further preferably 0 to 100 parts by mass for the monomer subjected to the polymerization reaction. 0.2 to 0.6 parts by mass, most preferably 0.2 to 0.5 parts by mass. The amount of the chain transfer agent to be used is preferably 2500 to 10000 parts by mass, more preferably 3000 to 9000 parts by mass, and still more preferably 3500 to 6000 parts by mass with respect to 100 parts by mass of the polymerization initiator. When the amount of the chain transfer agent is in the above range, the obtained methacrylic resin tends to have good moldability and high mechanical strength.

  The solvent used in the case of solution polymerization in the radical polymerization method for the production of each polymer contained in the methacrylic resin is not limited as long as it can dissolve the monomer and the polymer, but aromatic solvents such as benzene, toluene, and ethylbenzene can be used. Group hydrocarbons are preferred. These solvents can be used alone or in combination of two or more. The amount of the solvent used can be appropriately set from the viewpoint of the viscosity of the reaction solution and the productivity. The amount of the solvent to be used is, for example, preferably 100 parts by mass or less, more preferably 90 parts by mass or less, based on 100 parts by mass of the polymerization reaction raw material.

  The temperature during the polymerization reaction is preferably 100 to 200C, more preferably 110 to 180C. When the polymerization temperature is 100 ° C. or higher, productivity tends to be improved due to an increase in polymerization rate and a decrease in viscosity of the polymerization solution. Further, when the polymerization temperature is 200 ° C. or lower, the control of the polymerization rate becomes easy, and the generation of by-products is suppressed, so that the coloring of the methacrylic resin of the present invention can be suppressed. The time of the polymerization reaction is preferably 0.5 to 4 hours, more preferably 1.5 to 3.5 hours, and still more preferably 1.5 to 3 hours. In the case of a continuous flow reactor, the time for such a polymerization reaction is the average residence time in the reactor. When the temperature at the time of the polymerization reaction and the time of the polymerization reaction are within the above ranges, a methacrylic resin having excellent transparency can be produced with high efficiency.

  The polymerization conversion in the radical polymerization method for producing each polymer contained in the methacrylic resin is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and further preferably 35 to 65% by mass. When the polymerization conversion rate is 20% by mass or more, removal of the remaining unreacted monomer becomes easy, and the appearance of a molded article made of a methacrylic resin tends to be improved. When the polymerization conversion is 70% by mass or less, the viscosity of the polymerization liquid tends to be low, and the productivity tends to be improved.

  The radical polymerization may be performed using a batch reactor, but is preferably performed using a continuous flow reactor from the viewpoint of productivity. In a continuous flow type reaction, for example, a polymerization reaction raw material (mixed liquid containing a monomer, a polymerization initiator, a chain transfer agent, and the like) is prepared under a nitrogen atmosphere or the like, and is supplied to the reactor at a constant flow rate. Withdraw the liquid in the reactor at a flow rate corresponding to the amount. As the reactor, a tubular reactor that can be brought into a state close to a plug flow and / or a tank reactor that can be brought into a state close to complete mixing can be used. Further, continuous flow polymerization may be performed in one reactor, or continuous flow polymerization may be performed by connecting two or more reactors. In the present invention, it is preferable to employ at least one continuous flow tank reactor. The amount of liquid in the tank reactor during the polymerization reaction is preferably 1/4 to 3/4, more preferably 1/3 to 2/3, of the volume of the tank reactor. The reactor is usually equipped with a stirrer. Examples of the stirring device include a static stirring device and a dynamic stirring device. Examples of the dynamic stirrer include a max blend stirrer, a stirrer having a lattice-like blade rotating around a vertical rotary shaft arranged in the center, a propeller stirrer, a screw stirrer, and the like. . Of these, a Max Blend stirrer is preferably used from the viewpoint of uniform mixing.

  After the completion of the polymerization, if necessary, volatile components such as unreacted monomers are removed. The removal method is not particularly limited, but heat devolatilization is preferred. Examples of the devolatilization method include an equilibrium flash method and an adiabatic flash method. The devolatilization temperature by the adiabatic flash method is preferably 200 to 280C, more preferably 220 to 260C. The time for heating the resin by the adiabatic flash method is preferably 0.3 to 5 minutes, more preferably 0.4 to 3 minutes, and still more preferably 0.5 to 2 minutes. When devolatilization is performed in such a temperature range and heating time, a methacrylic resin with less coloring is easily obtained. The removed unreacted monomer can be recovered and used again for the polymerization reaction. The yellow index of the recovered monomer may be increased by heat applied during the recovery operation or the like. The recovered monomer is preferably purified by an appropriate method to reduce the yellow index.

  The methacrylic resin of the present invention can be in the form of pellets or the like in order to enhance convenience during storage, transportation, or molding. In order to obtain a molded article containing the methacrylic resin of the present invention, molding may be performed plural times. For example, after the methacrylic resin of the present invention is molded to obtain a pellet-shaped molded product, the pellet-shaped molded product can be further molded to obtain a molded product having a desired shape.

In the methacrylic resin of the present invention, if necessary, an antioxidant, a thermal deterioration inhibitor, an ultraviolet absorber, a light stabilizer, a lubricant, a mold release agent, a polymer processing aid, an antistatic agent, a flame retardant, a dye / pigment Various additives such as a light diffusing agent, an organic dye, a matting agent, and a phosphor may be added. The amount of such various additives is preferably 7% by mass or less, more preferably 5% by mass or less, and still more preferably 4% by mass or less, based on the methacrylic resin of the present invention.
Various additives may be added to the polymerization reaction liquid at the time of producing the methacrylic resin, may be added to the methacrylic resin produced by the polymerization reaction, may be added at the time of the production of the molded body .

The antioxidant alone is effective in preventing the resin from being oxidized and degraded in the presence of oxygen. For example, phosphorus-based antioxidants, hindered phenol-based antioxidants, thioether-based antioxidants and the like can be mentioned. One of these antioxidants may be used alone, or two or more thereof may be used in combination. Among them, a phosphorus-based antioxidant and a hindered phenol-based antioxidant are preferable from the viewpoint of an effect of preventing deterioration of optical characteristics due to coloring, and a combined use of a phosphorus-based antioxidant and a hindered phenol-based antioxidant is more preferable.
When a phosphorus-based antioxidant and a hindered phenol-based antioxidant are used in combination, the amount of the phosphorus-based antioxidant: the amount of the hindered phenol-based antioxidant is 1: 5 to 2: 1 is preferable, and 1: 2 to 1: 1 is more preferable.

  Examples of the phosphorus-based antioxidant include 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite (manufactured by ADEKA; trade name: ADK STAB HP-10) and tris (2,4-di-t). -Butylphenyl) phosphite (manufactured by BASF; trade name: IRGAFOS168), 3,9-bis (2,6-di-t-butyl-4-methylphenoxy) -2,4,8,10-tetraoxa-3 , 9-diphosphaspiro [5.5] undecane (made by ADEKA; trade name: ADK STAB PEP-36) and the like are preferable.

  Hindered phenolic antioxidants include pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (manufactured by BASF; trade name IRGANOX1010), octadecyl-3- (3,5-Di-tert-butyl-4-hydroxyphenyl) propionate (manufactured by BASF; trade name IRGANOX1076) is preferred.

The thermal degradation inhibitor is capable of preventing thermal degradation of a resin by capturing polymer radicals generated when exposed to high heat under a substantially oxygen-free state.
Examples of the thermal deterioration inhibitor include 2-t-butyl-6- (3′-t-butyl-5′-methyl-hydroxybenzyl) -4-methylphenyl acrylate (Sumitomo Chemical Co .; trade name Sumilizer GM); 2,4-di-t-amyl-6- (3 ′, 5′-di-t-amyl-2′-hydroxy-α-methylbenzyl) phenyl acrylate (Sumitomo Chemical; trade name Sumilizer GS) and the like. preferable.

An ultraviolet absorber is a compound having the ability to absorb ultraviolet light, and is said to have a function of mainly converting light energy to heat energy.
Examples of the ultraviolet absorber include benzophenones, benzotriazoles, triazines, benzoates, salicylates, cyanoacrylates, oxalic anilides, malonic esters, and formamidines. These may be used alone or in combination of two or more.

  Benzotriazoles are highly effective as an ultraviolet absorber when the film of the present invention is applied to optical applications because it has a high effect of suppressing deterioration of optical properties such as coloring due to ultraviolet irradiation. Examples of benzotriazoles include 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol (manufactured by BASF; trade name TINUVIN329), 2- (2H- Benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol (manufactured by BASF; trade name TINUVIN234), 2,2′-methylenebis [6- (2H-benzotriazole-2) -Yl) -4-t-octylphenol] (manufactured by ADEKA; LA-31), 2- (5-octylthio-2H-benzotriazol-2-yl) -6-tert-butyl-4-methylphenol and the like are preferable. .

  Further, as a triazine ultraviolet absorber, 2,4,6-tris (2-hydroxy-4-hexyloxy-3-methylphenyl) -1,3,5-triazine (ADEKA; LA-F70) And hydroxyphenyltriazine-based ultraviolet absorbers (manufactured by BASF; TINUVIN477 and TINUVIN460), and 2,4-diphenyl-6- (2-hydroxy-4-hexyloxyphenyl) -1,3,5- Triazine and the like can be mentioned.

  Furthermore, when it is desired to particularly effectively absorb light having a wavelength of 380 to 400 nm, WO 2011/089794, WO 2012/124395, JP 2012-012476 A, JP 2013-023461 A, JP-A-2013-112790, JP-A-2013-194037, JP-A-2014-62228, JP-A-2014-88542, JP-A-2014-88543, and the like. It is preferable to use a metal complex having a ligand as an ultraviolet absorber.

  A light stabilizer is a compound that is said to have a function of capturing radicals generated mainly by oxidation by light. Suitable light stabilizers include hindered amines such as compounds having a 2,2,6,6-tetraalkylpiperidine skeleton.

  Examples of the lubricant include stearic acid, behenic acid, stearamic acid, methylenebisstearamide, hydroxystearic acid triglyceride, paraffin wax, ketone wax, octyl alcohol, and hardened oil.

  Examples of the release agent include higher alcohols such as cetyl alcohol and stearyl alcohol; and higher glycerin fatty acid esters such as monoglyceride stearate and diglyceride stearate. In the present invention, it is preferable to use a higher alcohol and a glycerin fatty acid monoester in combination as a release agent. When a higher alcohol and a glycerin fatty acid monoester are used in combination, the ratio is not particularly limited, but the amount of the higher alcohol used: the amount of the glycerin fatty acid monoester is 2.5: 1 to 3. 5: 1 is preferred, and 2.8: 1 to 3.2: 1 is more preferred.

As the polymer processing aid, generally, polymer particles having a particle diameter of 0.05 to 0.5 μm, which can be produced by an emulsion polymerization method, are used. The polymer particles may be monolayer particles composed of polymers having a single composition ratio and a single intrinsic viscosity, or multilayer particles composed of two or more polymers having different composition ratios or intrinsic viscosities. You may. Among these, particles having a two-layer structure having a polymer layer having a low intrinsic viscosity in the inner layer and a polymer layer having a high intrinsic viscosity of 5 dl / g or more in the outer layer are preferred. The polymer processing aid preferably has an intrinsic viscosity of 3 to 6 dl / g. If the intrinsic viscosity is too small, the effect of improving the moldability tends to be low. If the intrinsic viscosity is too large, the molding processability of the copolymer tends to decrease.
Examples of antistatic agents include sodium heptylsulfonate, sodium octylsulfonate, sodium nonylsulfonate, sodium decylsulfonate, sodium dodecylsulfonate, sodium cetylsulfonate, sodium octadecylsulfonate, sodium diheptylsulfonate, heptylsulfonate Potassium, potassium octyl sulfonate, potassium nonyl sulfonate, potassium decyl sulfonate, potassium dodecyl sulfonate, potassium cetyl sulfonate, potassium octadecyl sulfonate, potassium diheptyl sulfonate, lithium heptyl sulfonate, lithium octyl sulfonate, nonyl sulfone Lithium oxide, lithium decyl sulfonate, lithium dodecyl sulfonate, lithium cetyl sulfonate, octadecyl sulfone Lithium, alkyl sulfonates lithium diheptyl acid and the like, and the like.
Examples of the flame retardant include magnesium hydroxide, aluminum hydroxide, hydrated aluminum silicate, hydrated magnesium silicate, metal hydrate having a hydroxyl group or water of crystallization such as hydrotalcite, and phosphoric acid such as amine polyphosphate and phosphate ester. Compounds, silicon compounds, etc., such as trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, tricyclohexyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, and dimethylethyl. Phosphate ester-based flame retardants such as phosphate, methyl dibutyl phosphate, ethyl dipropyl phosphate, and hydroxyphenyl diphenyl phosphate are preferred.

  As dyes and pigments, red organic pigments such as para red, fire red, pyrazolone red, thioindico red and perylene red; blue organic pigments such as cyanine blue and indanthrene blue; and green organic pigments such as cyanine green and naphthol green Pigments, and one or more of these can be used.

  As the organic dye, a compound having a function of converting ultraviolet light into visible light is preferably used. Examples of the phosphor include a fluorescent pigment, a fluorescent dye, a fluorescent white dye, a fluorescent brightener, and a fluorescent bleach.

  Examples of the light diffusing agent and the matting agent include glass fine particles, polysiloxane-based crosslinked fine particles, crosslinked polymer fine particles, talc, calcium carbonate, barium sulfate, and the like. It is preferable that the copolymer of the present invention does not contain an acid generator.

Examples of uses of the methacrylic resin of the present invention include signboard members such as advertising towers, stand signboards, sleeve signboards, transom signboards, and rooftop signboards; display parts such as showcases, partition boards, and store displays; fluorescent light covers, mood lighting covers, and the like. Lighting parts such as, lamp shades, light ceilings, light walls, chandeliers; interior parts such as pendants, mirrors, doors, domes, safety windows, partitions, stairs, stairs, balconies, roofs for leisure buildings, etc. Parts; Transportation parts such as aircraft windshield, pilot visor, motorcycle, motorboat windshield, bus light shield, automobile side visor, rear visor, head wing, headlight cover, tail lamp cover, etc .; Audio visual nameplate, stereo cover, TV Protective mask, vending machine display Electronic equipment parts such as cover, medical equipment parts such as incubators and X-ray parts; equipment-related parts such as machine covers, instrument covers, laboratory equipment, rulers, dials, observation windows, etc .; LCD protective plates, light guide plates, light guide films , Optical parts such as Fresnel lens, lenticular lens, front panel and diffuser of various displays; traffic related parts such as road signs, guide boards, curve mirrors, soundproof walls; surface materials for automobile interiors, surface materials for mobile phones, Film materials such as marking films; materials for home appliances such as washing machine canopies and control panels, rice cooker top panels; and others, greenhouses, large water tanks, box water tanks, clock panels, bathtubs, sanitaries, desk mats, games Examples include parts, toys, and masks for protecting the face during welding.
Examples of the vehicle applications include motorcycles, motorboat windshields, light-shielding plates for buses, side visors for vehicles, rear visors, head wings, headlight covers, tail lamp covers, meter panel covers, and surface materials for automobile interiors.

  Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. The measurement of physical properties and the like was performed by the following methods.

(Chromatogram measurement by GPC and determination of molecular weight distribution etc. based on the chromatogram)
4 mg of a resin material to be tested was dissolved in 5 ml of tetrahydrofuran, and the solution was further filtered through a 0.1 μm filter to prepare a solution to be tested.
A solution to be tested is applied to a GPC device (manufactured by Tosoh Corporation, HLC-8320) in which a column in which two TSKgelSuperMultipore HZM-M manufactured by Tosoh Corporation and SuperHZ4000 are connected in series and the detection unit is a differential refractive index detector is used. 20 μl was injected and the chromatogram was measured. Tetrahydrofuran was flowed as an eluent at a flow rate of 0.35 ml / min, and the column temperature was set at 40 ° C.
A calibration curve was prepared using data of 11 standard poly (methyl methacrylate) s. Standard polymethyl methacrylate having a molecular weight in the range of 1,000 to 2,200,000 was measured by gel permeation chromatography, and a calibration curve showing the relationship between retention time and molecular weight was created. The line connecting the point where the slope on the high molecular weight side of the chromatogram changes from zero to plus and the point where the slope of the peak on the low molecular weight side changes from minus to zero was defined as the baseline. If the chromatogram shows multiple peaks, draw a line connecting the point where the slope of the peak with the highest molecular weight changes from zero to plus and the point where the slope of the peak with the lowest molecular weight changes from minus to zero. The baseline was set.

The molecular weight M 1 in terms of polymethyl methacrylate corresponding to the retention time showing the maximum intensity value in the chromatogram was calculated from the calibration curve.
Further, the weight average molecular weight Mw and the number average molecular weight Mn in terms of polymethyl methacrylate were calculated from the chromatogram by a known calculation method.
The abundance of the molecular weight component equal to or less than 1/5 of the peak top molecular weight (Mp) was determined from the ratio of the area of the region surrounded by the chromatogram and the baseline.

(Melt viscosity)
The melt viscosity of the methacrylic resin at 250 ° C. and a shear rate of 2400 / sec was determined using a Capillograph (Model 1D, manufactured by Toyo Seiki Seisaku-sho, Ltd.) at 250 ° C. from a capillary having a diameter of 1 mmΦ and a length of 10 mm at a piston speed of 10 mm / min. And extruded at a speed of, and a numerical value evaluated from the shear stress generated at that time.

(Glass transition temperature [Tg])
The midpoint glass transition temperature determined from the DSC curve was defined as the glass transition temperature. The DSC curve was obtained by raising the temperature of the resin to be measured to 230 ° C. using a differential scanning calorimeter (DSC-50 (product number) manufactured by Shimadzu Corporation) in accordance with JIS K7121, and then cooling to room temperature. When the temperature was raised from room temperature to 230 ° C. at a rate of 10 ° C./min, it was obtained by differential scanning calorimetry at the second temperature rise.

(Scratch resistance evaluation / scratch test)
The methacrylic resin in the form of a pellet was hot-pressed at 230 ° C. to produce a flat plate having a thickness of 3 mm. This plate was conditioned at a temperature of 23 ° C. and a humidity of 50% RH for 24 hours, and then subjected to a scratch test using a scratch needle of R = 0.1 mm while changing the load in units of 10 g, and visually formed. The load (g) at which the product surface was scratched was measured.

  The following were prepared as methacrylic resins used in Examples and Comparative Examples.

・ Polymer [1]; 95.5% by mass of methyl methacrylate (MMA), 4.5% by mass of methyl acrylate (MA), Mp = 143,600, Mw / Mn = 2.16, prepared by suspension polymerization 2]; 100.0% by mass of methyl methacrylate (MMA), Mp = 76,000, Mw / Mn = 1.85, prepared by bulk polymerization. Polymer [3]: 95.0% by mass of methyl methacrylate (MMA), methyl Acrylate (MA) 5% by mass, Mp = 54,600, Mw / Mn = 1.90, prepared by bulk polymerization. Polymer [4]: 95.0% by mass of methyl methacrylate (MMA), 5% by mass of methyl acrylate (MA) %, Mp = 51,500, Mw / Mn = 1.93, prepared by bulk polymerization

(Example 1)
10 parts by mass of the polymer [1], 80 parts by mass of the polymer [2], and 10 parts by mass of the polymer [3] are mixed, melt-kneaded at 230 ° C. for 3 minutes in a Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.), and methacrylic. Resin [A-1] was produced.

(Example 2)
10 parts by mass of the polymer [1], 80 parts by mass of the polymer [2], and 10 parts by mass of the polymer [4] are mixed, and melt-kneaded at 230 ° C. for 3 minutes in a Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.) to give methacryl. Resin [A-2] was produced.

(Comparative Example 1)
70 parts by mass of the polymer [1] and 30 parts by mass of the polymer [3] are mixed and melt-kneaded at 230 ° C. for 3 minutes in a Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.) to produce a methacrylic resin [B-1]. did.

(Comparative Example 2)
10 parts by mass of the polymer [1], 40 parts by mass of the polymer [2], and 50 parts by mass of the polymer [3] are mixed, melt-kneaded at 230 ° C. for 3 minutes in a Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.), and methacrylic. Resin [B-2] was produced.

(Comparative Example 3)
30 parts by weight of the polymer [1] and 70 parts by weight of the polymer [3] are mixed and melt-kneaded at 230 ° C. for 3 minutes in a Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.) to produce a methacrylic resin [B-3]. did.
(Comparative Example 4)
100 parts by mass of the polymer [1] was melt-kneaded at 230 ° C. for 3 minutes in a Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.) to produce a methacrylic resin [B-4].

"Comprehensive evaluation as a molding material" in Table 1 was performed according to the following criteria.
A: excellent as a molding material B: slightly inferior as a molding material C: inferior as a molding material As shown in Table 1, the proportion of a molecular weight component having an MMA unit content of 98% or more and 1/5 or less of the peak top molecular weight. Is less than 7%, a molded body having a high glass transition temperature and a high surface hardness can be obtained. In addition, it can be seen from Examples and Comparative Example 4 that the fluidity is improved and the glass transition temperature is higher than that of a conventional material having the same surface hardness. As described above, the methacrylic resin of the present invention can provide a molded article having excellent fluidity, heat resistance, and surface hardness. That is, when the methacrylic resin of the present invention is used, a thin molded product having excellent heat resistance and surface hardness can be obtained with high production efficiency.

Claims (6)

  Gel permeation containing 98.0% by mass or more and 99.9% by mass or less of a repeating unit derived from methyl methacrylate, and 0.1% by mass or more and 2.0% by mass or less of a monomer other than methyl methacrylate. A methacrylic resin in which the proportion of a molecular weight component having 1/5 or less of the peak molecular weight obtained from an elution curve obtained by chromatography is less than 7%.   The methacrylic resin is obtained by mixing two or more kinds of polymers having different peak molecular weights, and the polymer having the highest molecular weight has a peak molecular weight of 110,000 or more and less than 180,000, and the polymer having the lowest molecular weight has a peak molecular weight of less than 180,000. 2. The methacrylic resin according to claim 1, wherein the methacrylic resin has a peak molecular weight of 36,000 or more and less than 110,000, and contains at least one polymer having 99.9% by mass or more of repeating units derived from methyl methacrylate.   The methacrylic resin according to claim 1 or 2, wherein a polymer containing 99.9% by mass or more of a repeating unit derived from methyl methacrylate is contained by 60% to 90% by mass.   The methacrylic resin according to any one of claims 1 to 3, which is used for injection molding.   The methacrylic resin according to any one of claims 1 to 4, wherein the methacrylic resin is used for a vehicle.   A molded article obtained from the methacrylic resin according to claim 1.