JP7184793B2 - Methacrylic resin, methacrylic resin composition and molded article - Google Patents

Description

The present invention relates to methacrylic resins. More specifically, the present invention relates to a methacrylic resin having high thermal decomposition resistance, less foaming during molding, and high heat resistance.

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

A methacrylic resin has high transparency and is useful as a material for moldings used for optical members, lighting members, signboard members, decorative members, and the like. A methacrylic resin composition having improved thermal decomposition resistance, heat resistance and moldability is known (Patent Document 1). By using the resin composition, a molded article having high surface smoothness and relatively high heat resistance can be obtained without foaming during molding. However, it cannot be said that the heat resistance is sufficient for applications that require heat resistance, such as in-vehicle displays.

JP 2017-48344 A

The present invention has been made in view of the above background, and its object is to provide a methacrylic resin, a methacrylic resin composition, and a molded article having high thermal decomposition resistance, less foaming during molding, and heat resistance. is to provide

The present invention provides the following methacrylic resin, methacrylic resin composition and molded article.
[1]
99% by mass to 100% by mass of a structural unit derived from methyl methacrylate and 0% by mass to 1% by mass of a structural unit derived from an acrylic ester,
The syndiotacticity (rr) in triad notation is X%, the weight average molecular weight is Y, the amount of residual methyl methacrylate in the methacrylic resin (A) is Z% by mass, and the remaining chains A methacrylic resin in which the value calculated by the formula: X·Y/(10000·Z·W) is 20 or more and 30 or less when the amount of the transfer agent is W ppm in the methacrylic resin (A).
[2]
The syndiotacticity (rr) in triad notation is 55 to 58%, the amount of residual methyl methacrylate in the methacrylic resin (A) is 0.7% by mass or less, and the residual methyl methacrylate dimer is 1000 ppm or less in methacrylic resin (A), the amount of residual methyl methacrylate trimer is 300 ppm or less in methacrylic resin (A), and the amount of residual chain transfer agent is 200 ppm in methacrylic resin (A). The methacrylic resin according to [1], wherein the glass transition temperature (Tg) satisfies the following formula.
Tg (°C) ≥ 121 when Mw ≥ 70,000
Tg (°C) ≥ 131-(700000/Mw) when Mw < 70,000
[3]
The methacrylic resin according to [1] or [2], which has a thermogravimetric retention of 90% or more measured in an air atmosphere at a constant temperature of 290°C for 10 minutes.
[4]
The methacrylic resin according to any one of [1] to [3], wherein the methyl methacrylate structural unit is 100% by mass.
[5]
The methacrylic resin according to any one of [1] to [4], which has a weight average molecular weight of 50,000 to 150,000.
[6]
A methacrylic resin composition further containing 5 to 50 parts by mass of a crosslinked rubber per 100 parts by mass of the methacrylic resin according to any one of [1] to [5].
[7]
A methacrylic resin composition further containing 0.0001 to 0.1 parts by mass of light diffusing particles per 100 parts by mass of the methacrylic resin according to any one of [1] to [5].
[8]
A molded article comprising the methacrylic resin according to any one of [1] to [5], the methacrylic resin composition according to [6], or the methacrylic resin composition according to [7].
[9]
The molded article according to [8], wherein the molded article is a film.
[10]
The method for producing a methacrylic resin according to any one of [1] to [5], including the step of polymerizing by a radical polymerization method at 90°C to 110°C.
[11]
The method for producing a methacrylic resin according to any one of [1] to [5], comprising a step of polymerizing by a continuous bulk polymerization method.
[12]
A molded article comprising a step of extruding the methacrylic resin according to any one of [1] to [5] or the methacrylic resin composition according to [6] or the methacrylic resin composition according to [7] from a die. Production method.

According to the present invention, it is possible to provide a methacrylic resin, a methacrylic resin composition, and a molded article having high thermal decomposition resistance, little foaming during molding, and heat resistance.

[Methacrylic resin (A)]
The methacrylic resin (A) of the present invention contains 99% by mass or more of structural units derived from methyl methacrylate. In the methacrylic resin (A), the content of structural units derived from methyl methacrylate is preferably 99.5% by mass or more, more preferably 100% by mass.
Here, the "structural unit" is derived from the monomer, and the calculation of the proportion of each structural unit does not include components other than the monomer such as chain transfer agents and polymerization initiators. In addition, the ratio of "structural units" is calculated based on the tetramer or higher methacrylic resin, and raw material monomers, dimers, and trimers such as methyl methacrylate and acrylic esters are not taken into account in the calculation.

Examples of structural units other than those derived from methyl methacrylate include methyl acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and 2-ethyl (meth)acrylate. (meth)acrylic acid alkyl esters such as hexyl; acrylate aryl esters such as phenyl acrylate; cycloalkyl acrylates such as cyclohexyl acrylate and norbornenyl acrylate; aromatic vinyls such as styrene and α-methylstyrene Acrylamide; methacrylamide; acrylonitrile; methacrylonitrile; Among these, the structural unit of (meth)acrylic acid ester is preferable because it is easy to copolymerize and a resin having high transparency can be obtained. As used herein, "acrylic acid ester" includes acrylic acid alkyl esters, acrylic acid aryl esters, and acrylic acid cycloalkyl esters.

The content of structural units other than those derived from methyl methacrylate is preferably 1% by mass or less, more preferably 0.5% by mass or less, and most preferably 0.1% by mass or less.

In particular, the content of structural units derived from acrylic acid ester is 0% by mass to 1% by mass. Preferably, it is 0% by mass, that is, it is not contained. When the content of the structural unit derived from acrylic acid ester exceeds 1% by mass, the acid value of the methacrylic resin (A) tends to increase.

The methacrylic resin (A) of the present invention has a triad syndiotacticity (rr) of X%, a weight average molecular weight of Y, and an amount of residual methyl methacrylate in the methacrylic resin (A). When the amount of the remaining chain transfer agent is W ppm or less in the methacrylic resin (A), the value calculated by the formula: X Y / (10000 Z W) is 20 30 or less, preferably 21 or more and 29 or less. When the value calculated by the formula: X·Y/(10000·Z·W) is small, the heat resistance tends to be low, and the resulting film tends to have low impact resistance and toughness. When the value calculated by the formula: X·Y/(10000·Z·W) is large, the moldability tends to be poor and the thermal decomposition resistance tends to be low.

The methacrylic resin (A) of the present invention has a triad syndiotacticity (rr) of 55% to 60%, preferably 56% to 59% or 55% to 58%. When the syndiotacticity is more than 60%, the glass transition temperature of the methacrylic resin is increased, but the thermal decomposition is decreased, and foaming is likely to occur because the molding temperature must be set high. On the other hand, if the syndiotacticity is less than 55%, the resin will have a low glass transition temperature and low heat resistance.

Here, the syndiotacticity (rr) of the triplet representation will be described. In a chain (diad) of structural units in a polymer molecule, those having the same configuration are called meso, and those having the opposite configuration are called racemo, which are denoted by m and r, respectively. The proportion of two chains (diad) in a chain of three consecutive structural units (triad) is racemo (denoted as rr) is the syndiotacticity of the triad representation. city (rr) (hereinafter simply referred to as "syndiotacticity (rr)").

The syndiotacticity (rr) (%) in triad notation is 0.6 when ^{the 1} H-NMR spectrum is measured in deuterated chloroform at 30° C. and TMS is set to 0 ppm from the spectrum. The area (P) of the region of ~0.95 ppm and the area (Q) of the region of 0.6 to 1.35 ppm are measured, and the value is calculated by the formula: (P/Q) x 100.

The methacrylic resin (A) of the present invention preferably has a weight average molecular weight (hereinafter referred to as “Mw”) of 50,000 to 150,000, more preferably 55,000 to 120,000, and even more preferably 57,000 to 100,000. When the Mw is 50,000 or more, the resulting film tends to be excellent in impact resistance and toughness. When it is 150,000 or less, the moldability of the methacrylic resin is enhanced, so that the resulting film tends to have a uniform thickness and excellent surface smoothness. Further, when the methacrylic resin (A) is produced by continuous bulk polymerization, Mw is preferably 100,000 or less from the viewpoint of ease of control of polymerization.

In the methacrylic resin (A) of the present invention, the ratio of Mw to the number average molecular weight (hereinafter referred to as "Mn") (Mw/Mn: this value is hereinafter referred to as "molecular weight distribution") is preferably 1.2. ~2.5, more preferably 1.5 to 2.0. When the molecular weight distribution is 1.2 or more, the fluidity of the methacrylic resin is improved, and the obtained film tends to have excellent surface smoothness. tend to be better. Mw and Mn are values obtained by converting the chromatogram measured by gel permeation chromatography (GPC) into the molecular weight of standard polystyrene.

The methacrylic resin (A) of the present invention has a melt flow rate of preferably 0.1 g/10 min or more, more preferably 0, measured under conditions of 230° C. and a load of 3.8 kg in accordance with JIS K7210. .5 to 30 g/10 min, more preferably 1.0 to 20 g/10 min, most preferably 1.1 to 5 g/10 min.

In one preferred embodiment of the present invention, the glass transition temperature of the methacrylic resin (A) satisfies the following formula.

Tg (°C) ≥ 121 when Mw ≥ 70,000
Tg (° C.)≧131−(700000/Mw) when Mw<70,000.

In another preferred embodiment of the present invention, the glass transition temperature of the methacrylic resin (A) is preferably 120°C or higher, more preferably 121°C or higher, even more preferably 122°C or higher. The upper limit of the glass transition temperature of the methacrylic resin is usually 125°C or lower, preferably 124°C or lower, more preferably 123°C or lower. The glass transition temperature can be controlled by adjusting the molecular weight and syndiotacticity (rr). When the glass transition temperature is within this range, deformation such as heat shrinkage of the obtained film is unlikely to occur, and thermal decomposition of the resin during molding of a molded article such as a film is easily suppressed.

The acetic acid-equivalent acid value of the methacrylic resin (A) of the present invention is 40 ppm or less, preferably 30 ppm or less, more preferably 20 ppm or less from the viewpoint of good thermal decomposition resistance. If the acid value in terms of acetic acid is too high, not only is the thermal decomposition resistance inferior, but also it reacts with other compounds during molding to generate gels and the like, which may cause defects in the molded product, which is not preferable.

Evaluation of the acid value is a value calculated as the amount of acetic acid contained with respect to the weight of the methacrylic resin (A) after converting the acid value of JIS K 0070:1992 into the amount of acetic acid instead of converting it into KOH. Specifically, it may be measured by the method described in Examples.

The thermogravimetric retention rate of the methacrylic resin (A) of the present invention measured in an air atmosphere at a constant temperature of 290°C for 10 minutes is preferably 90% or more, more preferably 91% or more, and more preferably 92%, from the viewpoint of thermal decomposition resistance. The above is most preferable.

The thermogravimetric retention rate is measured using a thermogravimetric analyzer (TGA, manufactured by Shimadzu Corporation), and the methacrylic resin (A) is heated from 50°C to 290°C under an air atmosphere at a dry air flow rate of 50 ml/min. After raising the temperature at 20° C./min, the thermogravimetric loss can be measured under the condition of holding at 290° C. for 10 minutes in an air atmosphere. For example, based on the weight (X1) at 50°C (100% retention rate) and the weight (X2) when held at 290°C for 10 minutes, the thermal decomposition resistance can be evaluated by the following formula. It can be said that the higher the thermogravimetric retention, the higher the thermal decomposition resistance.

Thermal weight retention (%) = (X2/X1) x 100 (%)
The method for producing the methacrylic resin (A) is preferably a radical polymerization method from the viewpoints of little coloration, small acid value, good thermal decomposition resistance, and good productivity.

The radical polymerization method is preferably continuous bulk polymerization performed without a solvent from the viewpoint of obtaining a methacrylic resin (A) with a low impurity concentration. From the viewpoint of suppressing the generation of silver or coloring in the molded article, it is preferable to carry out the polymerization reaction with a low dissolved oxygen content. Moreover, the polymerization reaction is preferably carried out in an inert gas atmosphere such as nitrogen gas.

The polymerization initiator used in the radical polymerization method for producing the methacrylic resin (A) is not particularly limited as long as it generates reactive radicals. For example, t-hexylperoxyisopropyl monocarbonate, t-hexylperoxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, t-butyl peroxypivalate , t-hexyl peroxypivalate, t-butyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, 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. Among 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 60 to 140°C, more preferably 80 to 120°C. In addition, the polymerization initiator used for producing the methacrylic resin (A) has a hydrogen abstraction ability of preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less. Such polymerization initiators can be used singly or in combination of two or more. The amount of the polymerization initiator 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 monomers subjected to the polymerization reaction. is 0.005 to 0.007 parts by mass.

The hydrogen abstraction ability can be known from the technical data of the polymerization initiator manufacturer (for example, technical data of NOF Co., Ltd. "Hydrogen abstraction ability and initiator efficiency of organic peroxide" (created in April 2003)). . It can also be measured by a radical trapping method using α-methylstyrene dimer, that is, an α-methylstyrene dimer trapping method. The measurement is generally performed as follows. First, the polymerization initiator is cleaved in the coexistence of α-methylstyrene dimer as a radical trapping agent to generate radical fragments. Of the generated radical fragments, radical fragments with low hydrogen abstraction ability are added to the double bond of the α-methylstyrene dimer and captured. On the other hand, a radical fragment with a high hydrogen abstraction ability abstracts hydrogen from cyclohexane to generate a cyclohexyl radical, which is captured by addition to the double bond of α-methylstyrene dimer to generate a cyclohexane capture product. Therefore, the ratio (molar fraction) of radical fragments with high hydrogen abstraction ability to the theoretical amount of radical fragments generated, which is obtained by quantifying cyclohexane or cyclohexane-scavenging products, is defined as hydrogen abstraction ability.

Chain transfer agents used in the radical polymerization method for producing the methacrylic resin (A) include n-octylmercaptan, n-dodecylmercaptan, t-dodecylmercaptan, 1,4-butanedithiol, and 1,6-hexanedithiol. , ethylene glycol bisthiopropionate, butanediol bisthioglycolate, butanediol bisthiopropionate, hexanediol bisthioglycolate, hexanediol bisthiopropionate, trimethylolpropane tris-(β-thiopropionate Alkyl mercaptans such as pentaerythritol tetrakisthiopropionate and the like. Among these, monofunctional alkylmercaptans such as n-octylmercaptan and n-dodecylmercaptan are preferred. These chain transfer agents can be used singly or in combination of two or more.

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, and still more preferably 0 part by mass with respect to 100 parts by mass of the monomers subjected to the polymerization reaction. .2 to 0.6 parts by weight, most preferably 0.2 to 0.5 parts by weight. 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 used is within the above range, the obtained methacrylic resin (A) tends to have good moldability and high mechanical strength.

The temperature during the polymerization reaction is preferably 80 to 115°C, more preferably 90 to 110°C, still more preferably 95 to 105°C. When the polymerization temperature is 80° C. or higher, the productivity tends to improve due to the improvement of the polymerization rate and the low viscosity of the polymerization liquid. Further, when the polymerization temperature is 115° C. or lower, the polymerization rate can be easily controlled, the formation of by-products can be suppressed, and a methacrylic resin having a desired glass transition temperature can be obtained. The temperature during the polymerization reaction can be controlled by the jacket temperature of the reactor and the polymerization rate.

The polymerization reaction time is preferably 0.5 to 4 hours, more preferably 1.5 to 3.5 hours, still more preferably 1.5 to 3 hours. In the case of a continuous flow reactor, the polymerization reaction time is the average residence time in the reactor. When the polymerization reaction temperature and the polymerization reaction time are within the above ranges, a highly transparent methacrylic resin (A) can be produced with high efficiency.

The polymerization conversion rate in the radical polymerization method for producing the methacrylic resin (A) is preferably 20 to 70% by mass, more preferably 30 to 60% by mass, still more preferably 35 to 55% by mass. When the polymerization conversion rate is 20% by mass or more, it becomes easy to remove the remaining unreacted monomers in the case where a volatile matter removal step is provided, and the resulting methacrylic resin is less likely to foam, resulting in a molded product. appearance tends to be good. When the polymerization conversion rate is 70% by mass or less, the viscosity of the polymerization liquid tends to be low and the productivity tends to be improved.

Radical polymerization may be carried out using a batch reactor, but is preferably carried out using a continuous flow reactor from the viewpoint of productivity. In the continuous flow reaction, for example, a polymerization reaction raw material (a mixed solution containing a monomer, a polymerization initiator, a chain transfer agent, etc.) is prepared under a nitrogen atmosphere, etc., and supplied to the reactor at a constant flow rate. The liquid in the reactor is withdrawn at a flow rate corresponding to the amount. As the reactor, a tubular reactor that can be brought to close to plug flow and/or a tank reactor that can be brought to 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 stirring device. Stirring devices include static stirring devices and dynamic stirring devices. Examples of the dynamic stirring device include a Maxblend stirring device, a stirring device having grid-shaped blades rotating around a central vertical rotating shaft, a propeller stirring device, a screw stirring device, and the like. Among these, a Maxblend stirring device is preferably used from the viewpoint of uniform mixing.

After completion of the polymerization, volatile matter such as monomers, dimers, trimers and chain transfer agents is removed, if necessary. The removal method is not particularly limited, but heating devolatilization is preferred. The devolatilization method includes an equilibrium flash method and an adiabatic flash method. The devolatilization temperature by the adiabatic flash method is preferably 200 to 270°C, more preferably 220 to 260°C. 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, still more preferably 0.5 to 2 minutes. Devolatization in such a temperature range and heating time makes it easy to obtain a methacrylic resin (A) with little coloration and a low acid value. The removed unreacted monomers can be recovered and reused in the polymerization reaction. The yellow index of the recovered monomer may be increased by the heat applied during the recovery operation. The recovered monomer is preferably purified by an appropriate method such as distillation or adsorption purification using a column to reduce the acid value and yellow index.

Further, the polymer obtained after the polymerization and a resin mixture containing volatile components such as monomers, dimers, trimers, and chain transfer agents are transferred from the reactor to a twin-screw extruder equipped with a vent. It can be transferred continuously. This can be followed by an equilibrium or adiabatic flash through the twin screw extruder inlet, followed by devolatilization through the twin screw extruder vent.

In the adiabatic flashing, the pressure of the resin melt immediately before flashing is preferably 1.5 to 3.0 MPa, more preferably 2.0 to 2.5 MPa. If the pressure is less than 1.5 MPa, flashing becomes insufficient and residual monomer tends to increase. Conversely, if it exceeds 3.0 MPa, it tends to be difficult to obtain stable production.

The twin-screw extruder used in the present invention preferably has a vent. Preferably the vent is a vacuum vent or an open vent. At least one vent is provided downstream of the polymer inlet. The pressure in the vacuum vent is preferably 30 Torr or less, more preferably 15 Torr or less, still more preferably 9 Torr or less, and most preferably 6 Torr or less. If the pressure in the vacuum vent is within the above range, the devolatilization efficiency is good, and monomers, dimers, trimers, chain transfer agents, etc. remaining in the methacrylic resin (A) can be reduced. .

The screws of the twin screw extruder are preferably co-rotating twin screws. Compared to the uniaxial case, the shear energy given to the resin is large, and the degree of surface renewal is large, so devolatilization can be performed efficiently, so the remaining unreacted monomers, dimers, trimers, etc. can be reduced. . Moreover, the screw structure preferably has a kneading segment portion of 5% or more of the total length of the screw. The kneading segments include rotor segments, forward kneading discs, reverse kneading discs, and mixing gears.

The cylinder heating temperature of the twin-screw extruder is preferably 200 to 270°C, more preferably 220 to 260°C, even more preferably 230 to 250°C. If the temperature is lower than 210°C, it takes time to devolatilize, and devolatilization tends to be insufficient. Insufficient devolatilization may cause appearance defects such as silver in the molded product. Conversely, if the temperature exceeds 270° C., the amount of terminal double bonds in the methacrylic resin (A) increases and the acid value increases, making it difficult to ensure thermal decomposition resistance. There may also be increased formation of the aforementioned dimers and trimers.

The methacrylic resin (A) of the present invention preferably consists of only methacrylic resin, but when actually obtained as methacrylic resin (A), other optional components due to production conditions are present in trace amounts. There is Other components resulting from the manufacturing conditions include unreacted monomers, dimers, trimers, chain transfer agents, and the like. In this specification, for the sake of convenience, resins containing these other components are also referred to as methacrylic resins (A).

In the methacrylic resin (A) of the present invention, the content of the other components is preferably 1% by mass or less in the methacrylic resin (A). When the content of the other component is within this range, the decrease in glass transition temperature is reduced.

In the methacrylic resin (A) of the present invention, among the remaining unreacted monomers, the amount of residual methyl methacrylate in the methacrylic resin (A) is preferably 0.7% by mass or less, more preferably 0.6% by mass. % by mass or less, more preferably 0.5% by mass or less.

In the methacrylic resin (A) of the present invention, the amount of residual methyl methacrylate dimer in the methacrylic resin (A) is preferably 1000 ppm or less, more preferably 500 ppm or less, still more preferably 300 ppm or less.

In the methacrylic resin (A) of the present invention, the amount of residual methyl methacrylate trimer in the methacrylic resin (A) is preferably 300 ppm or less, more preferably 200 ppm or less, still more preferably 100 ppm or less, particularly 0 ppm.

In the methacrylic resin (A) of the present invention, the amount of residual chain transfer agent in the methacrylic resin (A) is preferably 200 ppm or less, more preferably 150 ppm or less, still more preferably 100 ppm or less.

[Methacrylic resin composition (B)]
The methacrylic resin (A) of the present invention can be used as a methacrylic resin composition (B) by adding ultraviolet absorbers, polycarbonate resins, phenoxy resins, crosslinked rubbers, light diffusion particles, and the like.

In one preferred embodiment, the methacrylic resin (A) of the present invention can be used as a methacrylic resin composition (B) by adding an ultraviolet absorber. That is, the methacrylic resin composition (B) can contain the methacrylic resin (A) and an ultraviolet absorber.

The ultraviolet absorber used in the present invention is a known ultraviolet absorber that may be blended with thermoplastic resins. If the molecular weight of the ultraviolet absorber is 200 or less, problems such as foaming may occur when molding the methacrylic resin composition (B), so the lower limit of the molecular weight of the ultraviolet absorber is preferably 300. or more, more preferably 500 or more, still more preferably 600 or more.

The amount of the ultraviolet absorber that can be contained in the methacrylic resin composition (B) of the present invention is preferably 0.1 to 5 parts by mass, preferably 0.5 to 3 parts by mass, with respect to 100 parts by mass of the methacrylic resin (A). parts by mass, and more preferably 1 to 2 parts by mass.

In general, UV absorbers are compounds that have the ability to absorb UV light. A UV absorber is a compound that is said to have the function of mainly converting light energy into heat energy.

Examples of UV absorbers include benzophenones, benzotriazoles, triazines, benzoates, salicylates, cyanoacrylates, oxalic acid anilides, malonic acid esters, formamidines and the like. These may be used individually by 1 type, or may be used in combination of 2 or more type. Among these, benzotriazoles (compounds having a benzotriazole skeleton) and triazines (compounds having a triazine skeleton) are preferred. Benzotriazoles or triazines are highly effective in suppressing deterioration (eg, yellowing) of resins due to ultraviolet rays.

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-tert-octylphenol] (ADEKA; LA-31), 2-(5-octylthio-2H-benzotriazol-2-yl)-6-tert-butyl-4-methylphenol, etc. be able to.

Triazines include 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine (ADEKA; LA-F70) and analogues thereof. Certain hydroxyphenyltriazine-based UV absorbers (manufactured by BASF; CGL777, TINUVIN460, TINUVIN479, etc.), 2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine, etc. can be mentioned.

The methacrylic resin (A) of the present invention can be used as a methacrylic resin composition (B) by adding a polycarbonate resin or a phenoxy resin. By containing a polycarbonate resin or a phenoxy resin, it is possible to obtain a methacrylic resin composition (B) whose retardation can be easily adjusted. The amount of the polycarbonate resin or phenoxy resin is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 7 parts by mass, and still more preferably 0.8 to 4 parts by mass with respect to 100 parts by mass of the methacrylic resin (A). part by mass.

The methacrylic resin (A) of the present invention can be used as a methacrylic resin composition (B) by adding a crosslinked rubber. That is, the methacrylic resin composition (B) can contain the methacrylic resin (A) and the crosslinked rubber.

By containing the crosslinked rubber, a molded article such as a film having high impact resistance can be obtained. The content of the crosslinked rubber in the methacrylic resin composition (B) is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, still more preferably 15 to 30 parts by mass, relative to 100 parts by mass of the methacrylic resin (A). part by mass.

The crosslinked rubber used in the present invention is a polymer exhibiting rubber elasticity in which polymer chains are crosslinked by structural units derived from a crosslinkable monomer. In addition, a crosslinkable monomer has two or more polymerizable functional groups in one monomer.

Examples of crosslinked rubbers include acrylic crosslinked rubbers and diene crosslinked rubbers. Copolymer rubbers, copolymer rubbers of conjugated diene monomers, crosslinkable monomers and other vinyl monomers, acrylic acid alkyl ester monomers, conjugated diene monomers and crosslinkable monomers Examples include copolymer rubbers of monomers and other vinyl monomers.

In the present invention, the crosslinked rubber is preferably contained in the methacrylic resin composition in the form of particles.

The crosslinked rubber particles may be single-layered particles consisting of only crosslinked rubber, or may be multi-layered particles consisting of crosslinked rubber and another polymer. Core-shell type particles comprising a core of crosslinked rubber and a shell of a polymer other than the crosslinked rubber are preferred as the form of the multilayered particles composed of crosslinked rubber and other polymer.

The volume-based average particle size of the crosslinked rubber particles used in the present invention is preferably 0.02 to 1 μm, more preferably 0.05 to 0.5 μm, still more preferably 0.1 to 0.3 μm.

By using the crosslinked rubber particle component having such a volume-based average particle size, defects in appearance of the molded article can be remarkably reduced. The volume-based average particle size in this specification is a value calculated based on electron microscope observation of the methacrylic resin composition (B) containing crosslinked rubber particles.

The methacrylic resin (A) of the present invention can be used as a methacrylic resin composition (B) by adding light diffusion particles. That is, the methacrylic resin composition (B) can contain the methacrylic resin (A) and light diffusion particles.

By containing the light diffusing particles, when the methacrylic resin composition (B) is made into a sheet, when light is introduced from a light source to one end surface of the sheet, the light is scattered in the thickness direction of the sheet while the other Light can be guided in the surface direction of the sheet toward the end face. In the embodiment in which the light diffusing particles are contained in the sheet, it is possible to provide a sheet with excellent light guiding performance at low cost without the need to separately provide a light diffusing layer by printing, surface unevenness processing, or the like.
The content of the light diffusion particles in the methacrylic resin composition (B) is preferably 0.0001 to 0.1 parts by mass, more preferably 0.0002 to 0.01 parts by mass, based on 100 parts by mass of the methacrylic resin (A). part by mass.

The light diffusion particles used in the present invention are particles that have a refractive index different from that of the methacrylic resin (A) and scatter light. Light diffusing particles as described in WO2010/113422 are preferred.

The volume average particle size (volume average diameter) d of the light diffusing particles is preferably 0.5 to 5 μm, more preferably 0.75 to 4 μm, and particularly preferably 1 to 3 μm. If the volume average particle diameter d of the light diffusing particles is less than 0.5 μm, a difference in color may occur between the vicinity of the light incident end surface of the molded body and the position away from it. If the volume average particle diameter d of the light diffusing particles is more than 5 μm, the light diffusing particles with relatively large particle diameters may become bright spots when the light source is turned on, which may impair the appearance. The volume-average particle diameter d in the present specification is a particle diameter obtained by photographing an electron micrograph of primary particles and using image analysis type particle size distribution measurement software.

In the methacrylic resin composition (B), the refractive index difference (Δn) between the methacrylic resin (A) and the light diffusion particles is preferably 0.3-3. If the refractive index difference (Δn) is less than 0.3, light cannot be extracted efficiently, and transparency may be inferior in spite of the brightness when the light source is turned on. More preferably, the refractive index difference (Δn) is 0.4 or more. On the other hand, when the refractive index difference (Δn) is greater than 3, the scattered light is predominantly backscattered, so the light cannot be extracted efficiently, and the transparency is inferior for the brightness when the light source is lit. Sometimes.

As the light diffusing particles, inorganic compound particles having a large refractive index difference with respect to the methacrylic resin (A) are preferably used. For example, titanium oxide and zinc oxide are preferably used.

If the volume-average particle size d of the light diffusing particles is too small, a change in color such as coloring may occur due to the Rayleigh scattering phenomenon. In addition, when the refractive index difference (Δn) is too small, a change in color such as coloring, which is thought to be caused by the Rayleigh scattering phenomenon, may occur. Specifically, the scattered light may be bluish near the light source and yellowish at a distance from the light source.

In order to suppress changes in color such as coloring that are thought to be caused by the Rayleigh scattering phenomenon, the product of the volume average particle size d (μm) of the light diffusing particles and the absolute value of the refractive index difference (Δn) (|Δn|・d ) is preferably 0.1 μm or more.

The methacrylic resin composition (B) of the present invention may contain other polymers in addition to the methacrylic resin (A), ultraviolet absorber, polycarbonate resin, phenoxy resin, crosslinked rubber and light diffusion particles.

Other polymers include polyolefin resins such as polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1, and polynorbornene; ethylene-based ionomers; polystyrene, styrene-maleic anhydride copolymers, high-impact polystyrene, Styrene-based resins such as AS resin, ABS resin, AES resin, AAS resin, ACS resin, and MBS resin; methyl methacrylate-based polymer, methyl methacrylate-styrene copolymer; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; , nylon 66, polyamide such as polyamide elastomer; polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyacetal, polyvinylidene fluoride, polyurethane, modified polyphenylene ether, polyphenylene sulfide, silicone modified resin; silicone rubber , acrylic thermoplastic elastomers; styrene thermoplastic elastomers such as SEPS, SEBS and SIS; olefin rubbers such as IR, EPR and EPDM. The amount of the other polymer that can be contained in the methacrylic resin composition (B) of the present invention is preferably 10% by mass or less, more preferably 5% by mass or less, and most preferably 1% by mass or less.

In addition to the ultraviolet absorber, the methacrylic resin composition (B) according to the present invention contains a filler, an antioxidant, a heat deterioration inhibitor, a light stabilizer, a lubricant, a release agent, a polymer processing aid, and an antistatic agent. Additives that are often blended in ordinary resins, such as agents, flame retardants, dyes and pigments, light diffusing agents, organic dyes, matting agents, and phosphors, may be included.

Examples of fillers include calcium carbonate, talc, carbon black, titanium oxide, silica, clay, barium sulfate, and magnesium carbonate. The amount of filler that can be contained in the methacrylic resin composition of the present invention is preferably 3% by mass or less, more preferably 1.5% by mass or less, and still more preferably 0% by mass.

Antioxidants are effective by themselves to prevent oxidation deterioration of resins in the presence of oxygen. Examples thereof include phosphorus antioxidants, hindered phenol antioxidants, thioether antioxidants, and the like. These antioxidants may be used alone or in combination of two or more. Among them, from the viewpoint of the effect of preventing deterioration of optical properties due to coloring, phosphorus antioxidants and hindered phenol antioxidants are preferable, and combined use of phosphorus antioxidants and hindered phenol antioxidants is more preferable.

When a phosphorus-based antioxidant and a hindered phenol-based antioxidant are used in combination, the amount of phosphorus-based antioxidant used: the amount of hindered phenol-based antioxidant used is in a mass ratio of 1:5 to 2: 1 is preferred, and 1:2 to 1:1 is more preferred.

Phosphorus-based antioxidants include 2,2-methylenebis(4,6-di-t-butylphenyl)octylphosphite (manufactured by ADEKA; trade name: ADEKA STAB HP-10), tris(2,4-di-t- Butylphenyl)phosphite (manufactured by BASF; trade name: IRGAFOS168), 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa 3,9 -Diphosphaspiro[5.5]undecane (manufactured by ADEKA; trade name: ADEKA STAB PEP-36) and the like are preferred.

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-t-butyl-4-hydroxyphenyl)propionate (manufactured by BASF; trade name IRGANOX1076) is preferred.

Thermal degradation inhibitors can prevent thermal degradation of resins by scavenging polymer radicals generated when exposed to high heat under substantially oxygen-free conditions.

Examples of the heat deterioration inhibitor include 2-t-butyl-6-(3′-t-butyl-5′-methyl-hydroxybenzyl)-4-methylphenyl acrylate (manufactured by Sumitomo Chemical; trade name Sumilizer GM), 2,4-di-t-amyl-6-(3′,5′-di-t-amyl-2′-hydroxy-α-methylbenzyl)phenyl acrylate (manufactured by Sumitomo Chemical; trade name Sumilizer GS) is preferred.

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

Lubricants include, for example, stearic acid, behenic acid, stearamic acid, methylenebisstearamide, hydroxystearic acid triglyceride, paraffin wax, ketone wax, octyl alcohol, hardened oil and the like.

Examples of release agents include higher alcohols such as cetyl alcohol and stearyl alcohol; and glycerin higher fatty acid esters such as stearic acid monoglyceride and stearic acid diglyceride. In the present invention, it is preferable to use higher alcohols and glycerin fatty acid monoester in combination as the release agent. When higher alcohols and glycerin fatty acid monoesters are used in combination, the ratio is not particularly limited, but the amount of higher alcohols used: the amount of glycerin fatty acid monoesters used is in a mass ratio of 2.5:1 to 3.5. 5:1 is preferred, and 2.8:1 to 3.2:1 is more preferred.

The polymer processing aid is a polymer compound having an average degree of polymerization of 3,000 to 40,000, and preferably contains 60% by mass or more of methyl methacrylate units and 40% by mass of vinyl-based monomer units copolymerizable therewith. % or less. Incidentally, the average degree of polymerization of the polymer processing aid can be measured at 20° C. using an automatic dilution capillary viscometer (Ubbelohde type) using chloroform as a solvent, and calculated as a degree of polymerization converted to PMMA.

As the polymer processing aid, polymer particles having a particle size of 0.05 to 0.5 μm, which can be usually produced by an emulsion polymerization method, can be used. The polymer particles may be monolayer particles composed of a polymer having a single composition ratio and a single intrinsic viscosity, or may be multilayer particles composed of two or more polymers having different composition ratios or intrinsic viscosities. may Among these, particles having a two-layer structure having an inner layer of a polymer layer having a low intrinsic viscosity and an outer layer of a polymer layer having a high intrinsic viscosity of 5 dl/g or more are preferred. The polymeric processing aid preferably has a limiting viscosity of 3 to 6 dl/g. If the intrinsic viscosity is too low, the moldability-improving effect tends to be low. If the intrinsic viscosity is too high, the moldability of the methacrylic resin composition tends to deteriorate. Specifically, METABLEN-P series manufactured by Mitsubishi Rayon Co., Ltd. and Paralloid series manufactured by Dow Chemical Co., Ltd. can be mentioned.

Examples of flame retardants include organic halogen flame retardants such as tetrabromobisphenol A, decabromodiphenyl oxide and brominated polycarbonate; non-halogen flame retardants such as antimony oxide, aluminum hydroxide, zinc borate and tricresyl phosphate. etc.

Antistatic agents include, for example, stearamidopropyldimethyl-β-hydroxyethylammonium nitrate.

Examples of dyes and pigments include titanium oxide and red iron oxide.

A compound having a function of converting ultraviolet light into visible light is preferably used as the organic dye.

Examples of light diffusing agents and matting agents include fine glass particles, polysiloxane-based crosslinked fine particles, crosslinked polymer fine particles, talc, calcium carbonate, barium sulfate, and the like.

Examples of phosphors include fluorescent pigments, fluorescent dyes, fluorescent white dyes, fluorescent whitening agents, and fluorescent bleaching agents.

Antioxidants, heat deterioration inhibitors, light stabilizers, lubricants, release agents, polymer processing aids, antistatic agents, flame retardants, dyes and pigments, which may be contained in the methacrylic resin composition (B) of the present invention, The total amount of the light diffusing agent, organic dye, matting agent, and phosphor is preferably 7% by mass or less, more preferably 5% by mass or less, still more preferably 4% by mass or less, and most preferably 1% by mass or less. be.

The methacrylic resin composition (B) of the present invention preferably contains 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more of the methacrylic resin (A) of the present invention.

The methacrylic resin (A) or methacrylic resin composition (B) of the present invention has a haze of 3.2 mm thickness of preferably 3.0% or less, more preferably 2.0% or less, and 1.5% or less. More preferred.

The methacrylic resin (A) or methacrylic resin composition (B) of the present invention can be in the form of pellets or the like in order to improve convenience during storage, transportation, or molding.

The methacrylic resin (A) or methacrylic resin composition (B) of the present invention can be polymerized by a known method. Examples of polymer reactions include imidization reactions described in JP-A-2008-273140, JP-A-2008-274187, JP-A-2010-254742 and JP-A-2010-261025, and grafting described in JP-A-2012-201831. reaction.

The methacrylic resin (A) or methacrylic resin composition (B) of the present invention can be formed into a molded article by a known molding method. Examples of molding methods include T-die method (laminate method, co-extrusion method, etc.), inflation method (co-extrusion method, etc.), compression molding method, blow molding method, calendar molding method, vacuum molding method, injection molding method (insert method, two-color method, press method, core-back method, sandwich method, etc.) and solution casting method.

In these molding methods, a molding die is generally used to mold the resin. For example, sheet molding rolls, film forming rolls, compression molding dies, blow molding dies, calender rolls, vacuum molding dies, injection molding dies, cast polymerization casting reactors, etc. type can be mentioned. Molds are often made of metal, but there are also non-metal molds such as rubber rolls and tempered glass.

The shape of the molded article of the present invention is arbitrary and not particularly limited, and may be, for example, a film, a sheet, a plate, or the like.

Applications of the molded product of the present invention include, for example, billboard parts such as advertising towers, stand signboards, sleeve signboards, transom signboards, and rooftop signboards; display parts such as showcases, partitions, and store displays; fluorescent lamp covers, and mood lighting. Lighting parts such as covers, lampshades, light ceilings, light walls, and chandeliers; interior parts such as pendants and mirrors; architecture such as doors, domes, safety window glass, partitions, stair wainscots, balcony wainscots, roofs of leisure buildings, etc. Airplane windshields, pilot visors, motorcycles, motorboat windshields, light shielding plates for buses, side visors for automobiles, rear visors, head wings, headlight covers, glazing materials, sunroofs, head-up displays, and other transportation related parts; acoustics Electronic device parts such as video nameplates, stereo covers, TV protective masks, display covers for vending machines; Medical device parts such as incubators and X-ray parts; Machine covers, instrument covers, laboratory equipment, rulers, dials, observation windows Equipment-related parts such as; light guide plate and film for front light of display device, light guide plate and film for backlight, liquid crystal protection plate, Fresnel lens, lenticular lens, front plate of various displays, diffusion plate, optical related parts such as reflector Parts: Traffic-related parts such as road signs, information boards, curved mirrors, and soundproof walls; Surface materials for automotive interiors, mobile phone surfaces, marking films, and other film materials; Canopy materials and control panels for washing machines, rice cookers Household appliance members such as top panels; Others include greenhouses, large water tanks, box water tanks, clock panels, bathtubs, sanitary items, desk mats, game parts, toys, face protection masks during welding, and the like.

Since the molded article of the present invention is excellent in weather resistance, it can be used for optical equipment such as various covers, various terminal boards, printed wiring boards, speakers, microscopes, binoculars, cameras, clocks, etc., and video/optical recording.・Components related to optical communication and information equipment such as cameras, VTRs, projection TVs, filters, prisms, Fresnel lenses, optical discs (VD, CD, DVD, MD, LD, etc.) board protection films, optical switches, optical connectors , liquid crystal display, light guide film/sheet for liquid crystal display, flat panel display, light guide film/sheet for flat panel display, plasma display, light guide film/sheet for plasma display, light guide film/sheet for electronic paper, retardation Film/sheet, polarizing film/sheet, polarizing plate protective film/sheet, polarizer protective film/sheet, wave plate, light diffusion film/sheet, prism film/sheet, reflective film/sheet, anti-reflection film/sheet, viewing angle Enlargement films/sheets, antiglare films/sheets, brightness enhancement films/sheets, display element substrates for liquid crystal and electroluminescence applications, touch panels, light guide films/sheets for touch panels, spacers between various front panels and various modules, etc. It is particularly suitable for optical applications.

Specifically, for example, mobile phones, digital information terminals, pagers, navigation systems, in-vehicle liquid crystal displays, liquid crystal monitors, light control panels, displays for OA equipment, displays for AV equipment, etc. Various liquid crystal display elements and electroluminescence displays It can be used for elements, touch panels, and the like. In addition, from the viewpoint of excellent weather resistance, for example, interior and exterior building members, curtain walls, roof members, roofing materials, window members, rain gutters, exteriors, wall materials, floor materials, building materials, It is particularly suitably applicable to known building material applications such as road construction members, retroreflective films and sheets, agricultural films and sheets, lighting covers, signboards, translucent sound insulation walls, and the like.

The molded article of the present invention can also be applied to solar cell surface protective films, solar cell satirical films, solar cell back surface protective films, solar cell base films, gas barrier film substrates, protective films for gas barrier films, and the like. It is possible.

The film of the present invention, which is one form of molded article, is not particularly limited by its manufacturing method. The film of the present invention can be produced, for example, by subjecting the methacrylic resin (A) or methacrylic resin composition (B) to a known method such as a solution casting method, a melt casting method, an extrusion molding method, an inflation molding method, or a blow molding method. It can be obtained by forming a film by Among these, the extrusion molding method is preferred. Extrusion can provide films with improved toughness, good handleability, and a good balance of toughness, surface hardness and stiffness. The temperature of the methacrylic resin (A) or methacrylic resin composition (B) discharged from the extruder is preferably set to 160 to 270°C, more preferably 220 to 260°C.

When forming a film by these known methods, it is preferable to perform filtration with a polymer filter before supplying the methacrylic resin (A) or the methacrylic resin composition (B) to the die plate. Foreign matter can be effectively removed by installing a polymer filter at the tip of the extruder. The polymer filter preferably has a filtration accuracy of 1 μm or more and 10 μm or less, more preferably 1 μm or more and 5 μm or less, and still more preferably 2 μm or more and 3 μm or less. As the polymer filter, a known one such as a leaf disk type or a candle type can be used. In the case of a methacrylic resin that is easily thermally decomposed, the heat generated during filtering through a polymer filter causes thermal decomposition, which may cause foaming and impair the quality of the film.

Among the extrusion molding methods, the methacrylic resin (A) or the methacrylic resin composition (B) is extruded from a T-die in a molten state from the viewpoint of obtaining a film with good surface smoothness, good specular gloss, and low haze. and then sandwiching it between two or more mirrored rolls or mirrored belts for molding. The mirror roll or mirror belt is preferably made of metal. The linear pressure between a pair of mirror-finished rolls or mirror-finished belts is preferably 2 N/mm or more, more preferably 10 N/mm or more, and even more preferably 30 N/mm or more.

Moreover, it is preferable that the surface temperature of both the mirror surface roll and the mirror surface belt is 130° C. or less. Moreover, it is preferable that at least one of the pair of mirror-finished rolls or mirror-finished belts has a surface temperature of 60° C. or higher. By setting the surface temperature to such a value, the methacrylic resin (A) or methacrylic resin composition (B) discharged from the extruder can be cooled at a faster rate than natural cooling, resulting in excellent surface smoothness and It is easy to produce a film with low haze.

The film of the present invention may be stretched. The stretching treatment increases the mechanical strength and makes it possible to obtain a film that is less likely to crack. The stretching method is not particularly limited, and examples thereof include a uniaxial stretching method, a simultaneous biaxial stretching method, a sequential biaxial stretching method, and a tubular stretching method. The temperature during stretching is preferably 100 to 200° C., more preferably 120 to 160° C., from the viewpoint that the film can be stretched uniformly and a high-strength film can be obtained. Stretching is usually carried out at 100 to 5000%/min based on length. Stretching is preferably carried out so that the area ratio is 1.5 to 8 times. A film with less heat shrinkage can be obtained by heat setting after stretching.

The thickness of the film of the present invention is not particularly limited, but when used as an optical film, the thickness is preferably 1 to 300 μm, more preferably 10 to 50 μm, still more preferably 15 to 40 μm.

The film of the present invention preferably has a haze of 0.2% or less, more preferably 0.1% or less at a thickness of 40 μm. Thereby, it is excellent in surface gloss and transparency. Moreover, in optical applications such as a liquid crystal protective film and a light guide film, it is preferable because the utilization efficiency of the light source increases. Furthermore, it is preferable because it is excellent in shaping accuracy when performing surface shaping.

The film of the present invention has high thermal decomposition resistance, little foaming during molding, and has heat resistance. display window protective films, light guide films, transparent conductive films coated with silver nanowires or carbon nanotubes on the surface, front panels of various displays, and the like. In particular, the film of the present invention is suitable for a polarizer protective film because it can reduce the retardation.

The film of the present invention has transparency and heat resistance. It can be used for sheets, front sheets for flexible solar cells, shrink films, and films for in-mold labels.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to the following examples. Measurements of physical properties and the like were carried out by the following methods.

(Polymerization conversion rate)
A GL Sciences Inc. column was used in a gas chromatograph GC-14A manufactured by Shimadzu Corporation. Inert CAP 1 (df = 0.4 μm, 0.25 mm ID × 60 m) was connected, the injection temperature was raised to 180 ° C., the detector temperature was raised to 180 ° C., and the column temperature was raised from 60 ° C. (held for 5 minutes). The temperature was raised to 200°C at a temperature rate of 10°C/min, and the temperature was maintained for 10 minutes.

(Weight average molecular weight (Mw), number average molecular weight (Mn), molecular weight distribution)
A chromatogram was measured by gel permeation chromatography (GPC) under the following conditions, and a value converted to the molecular weight of standard polystyrene was calculated. The baseline is the point where the slope of the high molecular weight peak on the GPC chart changes from zero to positive when viewed from the early retention time, and the point where the slope of the low molecular weight peak changes from negative to zero when viewed from the early retention time. A line connecting the points where
GPC device: HLC-8320 manufactured by Tosoh Corporation
Detector: Differential refractive index detector Column: Two TSKgel SuperMultipore HZM-M manufactured by Tosoh Corporation and SuperHZ4000 connected in series were used.
Eluent: Tetrahydrofuran Eluent flow rate: 0.35 ml/min Column temperature: 40°C
Calibration curve: Created using 10 standard polystyrene data

(Syndiotacticity (rr) in triplets)
^{The 1} H-NMR spectrum of the methacrylic resin was measured using a nuclear magnetic resonance spectrometer (ULTRA SHIELD 400 PLUS manufactured by Bruker) using deuterated chloroform as a solvent at room temperature and 64 times of integration. From the spectrum, the area (X) of the region of 0.6 to 0.95 ppm when TMS is 0 ppm and the area (Y) of the region of 0.6 to 1.35 ppm are measured. The indicated syndiotacticity (rr) was calculated by the formula: (X/Y)×100.

(residual monomer, dimer, trimer, chain transfer agent)
A GL Sciences Inc. column was used in a gas chromatograph GC-14A manufactured by Shimadzu Corporation. INERT CAP 1 (df=0.4 μm, 0.25 mm I.D.×60 m) was connected, analysis was performed under the following analysis conditions, and calculation was performed based thereon. Contained volatile matter can be measured for each type based on the retention time.
<Analysis conditions>
Injection temperature: 250°C
Detector temperature: 250°C
Column temperature conditions:
Initial temperature: 60°C
Initial temperature retention time: 5 minutes Heating rate: 10°C/min Maximum temperature: 250°C
Maximum temperature retention time: 10 minutes

(Glass transition temperature Tg)
A methacrylic resin and a methacrylic resin composition were first heated to 230°C using a differential scanning calorimeter (DSC-50 (manufactured by Shimadzu Corporation) (product number)) in accordance with JIS K7121, and then to room temperature. After that, the DSC curve was measured under the condition of raising the temperature from room temperature to 230°C at a rate of 10°C/min for the second time. The midpoint glass transition temperature obtained from the DSC curve measured during the second heating was taken as the glass transition temperature in the present invention.

(MFR)
The melt flow rate (MFR) of the resin sample was measured at 230° C. under a load of 3.8 kg according to JIS K7210.

(Evaluation of thermal decomposition resistance by thermal weight retention)
Using a thermogravimetry device (manufactured by Shimadzu Corporation, TGA-50 (product number)), the resin sample was heated from 50°C to 290°C at a rate of 20°C/min in an air atmosphere at a dry air flow rate of 50ml/min. After heating, the thermogravimetric loss was measured under the condition of holding at 290° C. for 10 minutes in an air atmosphere. Based on the weight (X1) at 50°C (100% retention rate) and the weight (X2) when held at 290°C for 10 minutes, the thermal decomposition resistance was evaluated by the following formula.
Thermal weight retention (%) = (X2/X1) x 100 (%)

(Acid value converted to acetic acid)
A resin sample is dissolved in chloroform, and the acid value is measured by titration with an aqueous potassium hydroxide solution according to the method described in JIS-K0070-1992. and
Using the following formula (I), the value obtained by converting the obtained acid value into acetic acid equivalent was used.
Acid value in terms of acetic acid (ppm) = (acid value/1000) x (60/56) x 1000000 (I)
In addition, the meaning of the numerical value in Formula (I) is as follows.
1000: Convert milligrams to grams 60: Molecular weight of acetic acid 56: Molecular weight of KOH 1000000: Convert to ppm units

(Heat shrink temperature)
A test piece having a length of 20 mm, a width of 5 mm and a thickness of 40 μm was cut from the biaxially stretched film. Here, the longitudinal direction of the test piece was parallel to the width direction (TD side) of the original film. Both ends of the test piece in the longitudinal direction (5 mm from both ends) were gripped with a pair of film chucks. At this time, the distance between the pair of film chucks was set to 10 mm. A tensile load of 2 g was applied to the biaxially stretched film by a pair of film chucks, and the film was attached to a stress/strain controlled thermomechanical analyzer (TMA). With the test piece set as described above, the temperature of the test piece was raised from 25° C. to 120° C. at a rate of 2° C./min. The temperature at which the biaxially stretched film starts to shrink was defined as the heat shrink temperature.

(Comprehensive evaluation)
Based on the criteria that a molded product with excellent heat resistance (glass transition temperature of the resin) can be obtained, comprehensive evaluation as a molding material was performed from the results such as acid value and thermal decomposition resistance, which are indicators of foaming during molding.
The evaluation was performed in three stages of A, B, and C.

(Example 1) (Production of methacrylic resin [A-1])
The inside of the autoclave equipped with a stirrer and sampling tube was purged with nitrogen. To this, 100 parts by mass of purified methyl methacrylate (MMA), 2,2′-azobis(2-methylpropionitrile) (hydrogen abstraction capacity: 1%, 1-hour half-life temperature: 83° C.) 0.012 Parts by mass and 0.45 parts by mass of n-octylmercaptan were added and stirred to obtain a raw material liquid. Nitrogen was sent into the raw material liquid to remove dissolved oxygen in the raw material liquid.

A tank-type reactor connected to the autoclave by piping was filled with the raw material liquid up to 2/3 of its capacity. The temperature was maintained at 100° C. and the polymerization reaction was first initiated in a batch mode. When the polymerization conversion rate reaches 55% by mass, the raw material solution is supplied from the autoclave to the tank reactor at a flow rate that gives an average residence time of 120 minutes, and the reaction solution is supplied at a flow rate corresponding to the supply flow rate of the raw material solution. The temperature was maintained at 100° C., and the reactor was switched to a continuous flow polymerization reaction. After switching, the polymerization conversion rate in the steady state was 45 mass %.

The reaction liquid extracted from the tank reactor in a steady state was supplied to a shell and tube heat exchanger having an internal temperature of 230° C. at a flow rate that gave an average residence time of 2 minutes, and was heated. Then, the heated reaction liquid was introduced into a flash evaporator to remove volatile matter mainly composed of unreacted monomers to obtain a molten resin. The molten resin from which the volatile matter was removed was supplied to a twin-screw extruder having an internal temperature of 230° C., extruded in the form of strands, and cut with a pelletizer to obtain a methacrylic resin [A-1].

After drying the methacrylic resin composition [A-1] at 80° C. for 12 hours, it was melt-kneaded at a discharge rate of 30 kg/hr using a 50 mmΦ vented single-screw extruder with an L/D of 34. After melt-kneading, the mixture is passed through a leaf disk filter with a filtration area of 0.75 m ² and a filtration accuracy of 5 μm using a gear pump, extruded at a temperature of 270° C. through a T-die with a width of 130 mm, and formed into a film on a metal mirror surface roll at 90° C. It was molded and taken out at a speed of 20 m/min to form a resin monolayer film having a thickness of 160 μm.

The unstretched film with a thickness of 160 μm obtained by the above method is cut into small pieces of 100 mm × 100 mm so that two sides are parallel to the extrusion direction, and a pantograph type biaxial stretching tester (manufactured by Toyo Seiki Co., Ltd. ), the glass transition temperature + 10 ° C., the stretching speed of 150% / min in one direction, the stretching ratio of 2 times in one direction, the direction parallel to the extrusion direction first, and then the direction perpendicular to the extrusion direction sequentially biaxial stretching (4 times the area ratio), stretched under the condition of holding for 10 seconds, then taken out at room temperature and quenched to obtain a biaxially stretched film with a thickness of 40 μm. Table 1 shows the measurement results of the obtained methacrylic resin [A-1] and the biaxially stretched film.

(Example 2) (Production of methacrylic resin [A-2])
Methacrylic resin [A-2] and two An axially stretched film was obtained. Table 1 shows the evaluation results.

(Example 3) (Production of methacrylic resin [A-3])
Methacrylic resin [A-3] and two An axially stretched film was obtained. Table 1 shows the evaluation results.

(Comparative Example 1) (Production of methacrylic resin [A-4])
0.0075 parts by mass of 2,2'-azobis(2-methylpropionitrile), 0.428 parts by mass of n-octylmercaptan, and a methacrylic resin [ A-4] and a biaxially stretched film were obtained. Table 1 shows the evaluation results.

(Comparative Example 2) (Production of methacrylic resin [A-5])
Methacrylic resin [A-5] and dimethacrylic resin [A-5] and two An axially stretched film was obtained. Table 1 shows the evaluation results.

(Comparative Example 3) (Production of methacrylic resin [A-6])
Methacrylic resin [A-6] and two An axially stretched film was obtained. Table 1 shows the evaluation results.

(Comparative Example 4) (Production of methacrylic resin [A-7])
0.0071 parts by mass of 2,2′-azobis(2-methylpropionitrile), 0.285 parts by mass of n-octylmercaptan, and a methacrylic resin [ A-7] and a biaxially stretched film were obtained. Table 1 shows the evaluation results. At 110° C., the biaxially stretched film had 10% shrinkage compared to Example 2, which had a comparable melt flow rate.

(Comparative Example 5) (Production of methacrylic resin [A-8])
100 parts by mass of methyl methacrylate, 8 parts by mass of methyl acrylate (MA), 0.0065 parts by mass of 2,2'-azobis(2-methylpropionitrile), 0.13 parts by mass of n-octyl mercaptan, polymerization temperature A methacrylic resin [A-8] and a biaxially stretched film were obtained in the same manner as in Comparative Example 1 except that the temperature was changed to 150°C. The MMA content and MA content were confirmed by ¹ H-NMR. Table 1 shows the evaluation results.

(Comparative Example 6) (Production of methacrylic resin [A-9])
Except for changing to 100 parts by mass of methyl methacrylate, 1.1 parts by mass of methyl acrylate, 0.0068 parts by mass of 2,2'-azobis(2-methylpropionitrile), and 0.235 parts by mass of n-octyl mercaptan A methacrylic resin [A-9] and a biaxially stretched film were obtained in the same manner as in Comparative Example 1. The MMA content and MA content were confirmed by ¹ H-NMR. Table 1 shows the evaluation results.

(Comparative Example 7) (Production of methacrylic resin [A-10])
To 100 parts by mass of methyl methacrylate, 0.451 parts by mass of 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) and 0.2 parts by mass of n-octylmercaptan were added and dissolved to form a raw material solution. Obtained. A mixture was obtained by mixing 150 parts by mass of ion-exchanged water, 0.03 parts by mass of sodium sulfate and 0.46 parts by mass of a suspension dispersant. A pressure-resistant polymerization tank was charged with the mixed solution and the raw material solution, and the temperature was raised to 35° C. while stirring in a nitrogen atmosphere to initiate a polymerization reaction. After 3 hours from the start of the polymerization reaction, the temperature was raised to 90° C., and stirring was continued for 1 hour to obtain a dispersion in which bead-like fine particles were dispersed. The resulting dispersion was filtered, and the fine particles were washed with ion-exchanged water and dried under reduced pressure of 100 Pa at 80° C. for 4 hours to obtain bead-like methacrylic resin [A-10]. The obtained methacrylic resin [A-10] is supplied to a twin-screw extruder controlled at 230° C. to separate and remove volatile components such as unreacted monomers, and then the resin component is extruded into strands. did. The strand was cut with a pelletizer to obtain a pellet-shaped compact. Film formation and biaxial stretching of the methacrylic resin [A-10] were carried out in the same manner as in Example 1. Table 1 shows the evaluation results.

Claims (10)

99% by mass to 100% by mass of a structural unit derived from methyl methacrylate and 0% by mass to 1% by mass of a structural unit derived from an acrylic ester,
The syndiotacticity (rr) in triad notation is X%, the weight average molecular weight (Mw) is Y, the amount of residual methyl methacrylate in the methacrylic resin (A) is Z% by mass, When the amount of the remaining chain transfer agent is W ppm in the methacrylic resin (A), the value calculated by the formula: X Y / (10000 Z W) is 20 or more and 30 or less,
It has a triad syndiotacticity (rr) of 56 to 58 %, a weight average molecular weight (Mw) of 57,000 to 100,000, and an amount of residual methyl methacrylate in the methacrylic resin (A) of 0.5%. 5% by mass or less, the amount of the remaining methyl methacrylate dimer in the methacrylic resin (A) is 500 ppm or less, and the amount of the remaining methyl methacrylate trimer in the methacrylic resin (A) is 10 ppm or less, the amount of the remaining chain transfer agent in the methacrylic resin (A) is 150 ppm or less, and the glass transition temperature (Tg) satisfies the following formula.
Tg (°C) ≥ 121 when Mw ≥ 70,000
Tg (°C) ≥ 131-(700000/Mw) when Mw < 70,000 2. The methacrylic resin according to claim 1, which has a thermogravimetric retention of 90% or more measured in an air atmosphere at a constant temperature of 290° C. for 10 minutes. 3. The methacrylic resin according to claim 1, wherein the methyl methacrylate structural unit is 100% by mass. A methacrylic resin composition further containing 5 to 50 parts by mass of a crosslinked rubber per 100 parts by mass of the methacrylic resin according to any one of claims 1 to 3. A methacrylic resin composition further comprising 0.0001 to 0.1 parts by mass of light diffusing particles per 100 parts by mass of the methacrylic resin according to any one of claims 1 to 3. A molded article comprising the methacrylic resin according to any one of claims 1 to 3, the methacrylic resin composition according to claim 4, or the methacrylic resin composition according to claim 5. The molded article according to claim 6, wherein the molded article is a film. The method for producing a methacrylic resin according to any one of claims 1 to 3, comprising a step of polymerizing by a radical polymerization method at 90°C to 110°C. The method for producing a methacrylic resin according to any one of claims 1 to 3, comprising a step of polymerizing by a continuous bulk polymerization method. A method for producing a molded article, comprising a step of extruding the methacrylic resin according to any one of claims 1 to 3, the methacrylic resin composition according to claim 4, or the methacrylic resin composition according to claim 5 from a die. .