JP7015116B2 - A methacrylic resin composition, a method for producing the methacrylic resin composition, pellets, and a molded product. - Google Patents

Description

The present invention relates to a methacrylic resin composition having a low content of minute foreign substances, a method for producing the methacrylic resin composition, and pellets and molded products containing the methacrylic resin composition.

In recent years, with the expansion of the display market, there is an increasing demand for clearer images, and there is a demand for optical materials having higher optical properties in addition to transparency, heat resistance, and strength.

As the optical material, an acrylic resin ((meth) acrylic acid ester polymer) has been attracting attention from the viewpoint of transparency, surface hardness, optical properties and the like. Further, in recent years, with the progress of flat displays such as liquid crystal displays, plasma displays, organic EL displays, infrared sensors, optical wave guides, etc. and the expansion of demand for optical members for in-vehicle applications, the heat resistance of transparent polymer materials for optics. As the demand for the acrylic resin is increasing, high heat resistance is also required for the acrylic resin.

The heat-resistant acrylic resin (hereinafter referred to as “heat-resistant acrylic resin”) is a lactone ring-containing polymer obtained by subjecting a polymer having a hydroxyl group and an ester group in the molecular chain to a lactone cyclization condensation reaction. (See, for example, Patent Documents 1, 2, 3, and 4), a maleimide-based copolymer copolymerized with maleimides (see, for example, Patent Document 5), and a polymer containing a glutaric acid anhydride skeleton (for example, patent). Reference 6) is known. Then, when producing these heat-resistant acrylic resins or heat-resistant acrylic resin compositions, when extruding them into a film or a sheet, an extruder is widely used.

However, since the extrusion temperature of the heat-resistant acrylic resin is higher than the extrusion temperature of a general acrylic resin and is close to the temperature at which the resin decomposes, many black foreign substances such as carbides and brown foreign substances are generated due to the deterioration of the resin. There is a tendency. When a heat-resistant acrylic resin or a heat-resistant acrylic resin composition is used in an injection molded product or a film, it is required to reduce foreign substances.

Therefore, there is disclosed a technique for removing foreign substances in a heat-resistant acrylic resin or a heat-resistant acrylic resin composition by using a filter such as a leaf disk type polymer filter when manufacturing an optical film (for example). , Patent Document 7).

Japanese Unexamined Patent Publication No. 2000-230016 Japanese Unexamined Patent Publication No. 2001-151814 Japanese Unexamined Patent Publication No. 2002-120326 Japanese Unexamined Patent Publication No. 2002-254544 Japanese Unexamined Patent Publication No. 09-324016 Japanese Unexamined Patent Publication No. 2006-241197 Japanese Unexamined Patent Publication No. 2012-25968

However, the technique disclosed in Patent Document 7 has a problem that large foreign matter can be generally removed by installing a polymer filter, but it is difficult to remove minute foreign matter smaller than the filter diameter.

With respect to this problem, it is possible to remove minute foreign substances to some extent by reducing the filter diameter. However, if the filter diameter is reduced, the resin pressure at the time of extrusion increases, so that the discharge amount must be reduced in order to keep the resin pressure low. As a result, there arises the problem of reduced productivity.

It is also conceivable to increase the frequency of filter replacement in order to reduce the content of minute foreign matter. However, there are problems such as an increase in burnt foreign matter due to deterioration of the resin due to retention in the extruder at the time of filter replacement, and a decrease in productivity due to production suspension.

During long-term operation, the resin composition is held for a long period of time while the inside of the extruder is held at a relatively high resin pressure, so that the resin-deteriorated foreign matter such as black foreign matter and brown foreign matter once captured by the filter is crushed. As a result, it becomes a minute foreign substance and passes through the filter, and there is also a problem that the content of the minute foreign substance increases while the apparently large foreign substance decreases. Therefore, it is required to suppress the generation of minute foreign substances as much as possible and improve the production stability (that is, continuous productivity) in long-term operation.

In view of the above-mentioned problems of the prior art, in the present invention, a methacrylic resin composition, which is excellent in continuous productivity, has a low content of foreign substances, and can produce a molded product having excellent physical properties and appearance. It is an object of the present invention to provide a method for producing the methacrylic resin composition, and pellets and molded products containing the methacrylic resin composition.

The present inventors have completed the present invention as a result of repeated diligent studies to solve the above-mentioned problems of the prior art.
That is, the present invention is as follows.

[1]
It contains 50% by mass or more of the methacrylic acid ester monomer unit (A), and has a maleimide-based structural unit (B-1), a glutaric acid anhydride-based structural unit (B-2), and a glutaric acid-based structural unit (B-). 3), and a methacrylic resin containing a structural unit (B) having a ring structure in at least one main chain selected from the group consisting of the lactone ring structural unit (B-4) .
The glass transition temperature is 110-160 ° C.
The weight loss rate when heated at 280 ° C. for 1 hour in a nitrogen atmosphere as measured by thermogravimetric analysis is 5% or less.
Measured with a particle counter, it contains 100 or less foreign substances having a particle size of 10 μm or more and less than 20 μm per 1 g , and contains 100 or less foreign substances having a particle size of 20 μm or more per 1 g .
A methacrylic resin composition characterized by this.
[2]
The methacrylic resin composition according to [1], wherein the weight loss rate when heated at 280 ° C. for 0.5 hours in air, which is measured by thermogravimetric analysis, is 20% or less.
[ 3 ]
The methacrylic resin composition according to [1] or [2] , wherein the number of bubbles having a major axis of 100 μm or more contained in 100 cm ² of the film formed by an extruder having a set temperature of 290 ° C. is less than five. thing.
[ 4 ]
The methacrylic resin composition according to any one of [1] to [ 3 ], which contains 95% by mass or more of the methacrylic resin.
[ 5 ]
With respect to 100 parts by mass of the methacrylic resin, 0.01 to 2 parts by mass of a hindered phenol-based antioxidant is contained, and a total of 0.01 to 2 parts of a phosphorus-based antioxidant and / or a sulfur-based antioxidant is contained. The methacrylic resin composition according to any one of [1] to [ 4 ], which comprises a part by mass.
[ 6 ]
The methacrylic resin composition according to any one of [1] to [ 5 ], wherein the glass transition temperature of the methacrylic resin is 110 ° C. or higher and 160 ° C. or lower.
[ 7 ]
The methacrylic resin contains the (A) monomer unit: 50 to 97% by mass, the structural unit (B) having a ring structure in the main chain: 3 to 30% by mass, and the methacrylic acid ester monomer. The methacrylic resin composition according to any one of [1] to [ 6 ], which comprises another polymerizable vinyl-based monomer unit (C): 0 to 20% by mass.
[ 8 ]
The (C) monomer unit is an aromatic vinyl-based monomer unit (C-1), an acrylic acid ester monomer unit (C-2), and a vinyl cyanide-based monomer unit (C-3). The methacrylic resin composition according to [ 7 ], which comprises at least one monomer unit selected from the group consisting of).
[ 9 ]
The methacrylic system according to [ 8 ], wherein the (C) monomer unit contains at least one monomer unit selected from the group consisting of a methyl acrylate unit, an ethyl acrylate unit, a styrene unit, and an acrylonitrile unit. Resin composition.
[ 10 ]
The methacrylic resin composition according to any one of [1] to [9], which contains 0.01 to 5 parts by mass of an ultraviolet absorber with respect to 100 parts by mass of the methacrylic resin.

[ 11 ]
A pellet comprising the methacrylic resin composition according to any one of [1] to [ 10 ].
[ 12 ]
It contains 50% by mass or more of the methacrylic acid ester monomer unit (A), and has a maleimide-based structural unit (B-1), a glutaric acid anhydride-based structural unit (B-2), and a glutaric acid-based structural unit (B-). It contains a methacrylic resin containing a structural unit (B) having a ring structure in at least one main chain selected from the group consisting of 3) and a lactone ring structural unit (B-4), and has a glass transition temperature of 110 to 160. A method for producing a methacrylic resin composition at ° C.
Including the step of extruding a methacrylic resin composition from a die using an extruder equipped with a feeder, a vent port and a pleated filter .
When extruding with the extruder, the discharge amount (discharge amount / number of holes) of the methacrylic resin composition per hour per hole of the die is 5 kg / (hr / piece) or more and 30 kg / (hr / piece). A method for producing a methacrylic resin composition, which comprises the following.
[ 13 ]
A molded product comprising the methacrylic resin composition according to any one of [1] to [ 10 ].
[ 14 ]
The molded product according to [ 13 ], which is an optical component.
[ 15 ]
The molded product according to [ 13 ], which is an optical film.
[ 16 ]
The molded body according to [ 13 ], which is a member for a vehicle.

According to the present invention, a methacrylic resin composition and a method for producing the methacrylic resin composition, which are excellent in continuous productivity, have a low content of foreign substances, and can produce a molded product having excellent physical properties and appearance. , And pellets and molded articles containing the methacrylic resin composition can be provided.

It is a figure which shows the outline of the elution curve when the methacrylic resin used for the methacrylic resin composition of this embodiment is measured by gel permeation chromatography (GPC).

Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail, but the present invention is not limited to the following description and is within the scope of the gist thereof. It can be modified in various ways.
In the following, the structural unit constituting the polymer constituting the methacrylic resin contained in the methacrylic resin composition of the present embodiment is referred to as "-monomer unit" and / or a plurality of the "-single". It is called "-structural unit" including "metric unit".
Further, the constituent material of the "-monomer unit" may be simply described as "-monomer" by omitting the "unit".

(Methyl resin)
The methacrylic resin contained in the methacrylic resin composition of the present embodiment contains 50% by mass or more of the methacrylic acid ester monomer unit (A) and has a ring structure in the main chain.

The monomer unit and / or the structural unit contained in the methacrylic resin is not particularly limited except that it contains 50% by mass or more of the methacrylic ester monomer unit (A), but the methacrylic ester monomer unit. (A): 50 to 97% by mass, structural unit having a ring structure in the main chain (B): 3 to 30% by mass, and other vinyl-based monomer units copolymerizable with the methacrylic acid ester monomer. (C): It is preferable to contain 0 to 20% by mass.

Hereinafter, the monomer unit and the structural unit contained in the methacrylic resin will be described in detail.

((Methacrylic acid ester monomer unit (A)))
The methacrylic acid ester monomer unit (A) (hereinafter, may be referred to as (A) monomer unit) constituting the methacrylic resin is a monomer represented by the following general formula (1). The unit is preferably used.

In the general formula (1), R ¹ represents a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and the alkyl group may be substituted with, for example, a hydroxyl group. R ¹ is preferably a methyl group.
R ² represents a group having 1 to 12 carbon atoms, preferably a hydrocarbon group having 1 to 12 carbon atoms, and the hydrocarbon group may be substituted with, for example, a hydroxyl group. ^R2 is preferably a group having 1 to 8 carbon atoms.

The monomer forming the methacrylic acid ester monomer unit (A) represented by the general formula (1) is not particularly limited, but the methacrylic acid ester monomer represented by the following general formula (2) can be used. It is preferable to use it.

In the general formula (2), R ¹ represents a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and the alkyl group may be substituted with, for example, a hydroxyl group. R ¹ is preferably a methyl group.
R ² represents a group having 1 to 12 carbon atoms, preferably a hydrocarbon group having 1 to 12 carbon atoms, and the hydrocarbon group may be substituted with, for example, a hydroxyl group. ^R2 is preferably a group having 1 to 8 carbon atoms.

Specific examples of such monomers include butyl methacrylate, ethyl methacrylate, methyl methacrylate, propyl methacrylate, isopropyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, methacrylic acid (2-ethylhexyl), and methacrylic acid (t). -Butylcyclohexyl), benzyl methacrylate, methacrylic acid (2,2,2-trifluoroethyl), etc., from the viewpoint of heat resistance, handleability, and optical properties, methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, etc. , Methacrylic acid phenyl and benzyl methacrylate are preferable, and methyl methacrylate is preferable from the viewpoint of availability and the like.
The methacrylic acid ester monomer may be used alone or in combination of two or more.

The methacrylic acid ester monomer unit (A) of the methacrylic resin is the methacrylic resin composition of the present embodiment and the molded product of the present embodiment by the structural unit (B) having a ring structure in the main chain described later. From the viewpoint of sufficiently imparting heat resistance to the resin, the methacrylic resin contains 50 to 97% by mass, preferably 55 to 96.5% by mass, more preferably 55 to 95% by mass, and even more preferably 60 to 60% by mass. It is contained in an amount of 93% by mass, more preferably 60 to 90% by mass.

((Structural unit (B) having a ring structure in the main chain))
The structural unit (B) having a ring structure in the main chain (hereinafter, may be referred to as (B) structural unit) constituting the methacrylic resin is a maleimide-based structural unit (B) from the viewpoint of heat resistance. -1), at least one structural unit selected from the group consisting of a glutaric acid anhydride-based structural unit (B-2), a glutarimide-based structural unit (B-3), and a lactone ring structural unit (B-4). It is preferable to include it.
As the structural unit (B) having a ring structure in the main chain, only one type may be used alone, or two or more types may be combined.

[Maleimide-based structural unit (B-1)]
As the maleimide-based structural unit (B-1) constituting the methacrylic resin, the structural unit represented by the following general formula (3) is preferably used.

In the general formula (3), R ¹ has a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, and a carbon number of carbon atoms. It represents any one selected from the group consisting of 6 to 12 aryl groups, and the alkyl group, alkoxy group, cycloalkyl group, and aryl group may have a substituent on the carbon atom.

The monomer for forming the maleimide-based structural unit (B-1) is not particularly limited, but for example, maleimide; N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide and the like. -Alkyl group substituted maleimide; N-phenylmaleimide, N-methylphenylmaleimide, N-ethylphenylmaleimide, N-butylphenylmaleimide, N-dimethylphenylmaleimide, N-hydroxyphenylmaleimide, N-methoxyphenylmaleimide, N- ( Examples thereof include N-aryl group-substituted maleimides such as o-chlorophenyl) maleimide, N- (m-chlorophenyl) maleimide, and N- (p-chlorophenyl) maleimide.
The above-mentioned monomer is preferably N-cyclohexylmaleimide, N-phenylmaleimide, N-methylphenylmaleimide, N- (o-chlorophenyl) maleimide, N- (m-chlorophenyl) from the viewpoint of imparting heat resistance and moisture heat resistance. ) Maleimide, N- (p-chlorophenyl) maleimide, more preferably N-cyclohexylmaleimide, N-phenylmaleimide, still more preferably N-phenyl, from the viewpoint of easy availability and imparting heat resistance. Maleimide can be mentioned.
As the maleimide-based structural unit (B-1) described above, only one type may be used alone, or two or more types may be used in combination.

[Glutaric acid anhydride-based structural unit (B-2)]
The glutaric acid anhydride-based structural unit (B-2) constituting the methacrylic acid-based resin may be formed after the resin polymerization.
(B-2) As the structural unit, the structural unit represented by the following general formula (4) is preferably used.

In the general formula (4), R ¹ and R ² each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and the alkyl group is, for example, a hydroxyl group. It may be replaced.
As the above-mentioned glutaric anhydride-based structural unit (B-2), only one type may be used alone, or two or more types may be used in combination.

The method for forming the glutaric anhydride-based structural unit (B-2) is not particularly limited, but for example, a monomer having a structure represented by the following general formula (5) can be used as the above-mentioned methacrylic acid ester monomer unit. Examples thereof include a method of copolymerizing with the monomer forming (A) and then cyclizing by heat treatment in the presence / absence of a catalyst.

In the general formula (5), R ¹ represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and the alkyl group may be substituted with, for example, a hydroxyl group.
R ² represents a hydrogen atom or t-butyl.

Further, as long as the effect of the present invention can be exhibited, the monomer having the structure represented by the general formula (5) may remain unreacted in the methacrylic resin.

[Glutarimide-based structural unit (B-3)]
The glutarimide-based structural unit (B-3) constituting the methacrylic resin may be formed after the resin polymerization.
(B-3) As the structural unit, the structural unit represented by the following general formula (6) is preferably used.

In the general formula (6), R ¹ and R ² each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and the alkyl group is, for example, a hydroxyl group. It may be replaced.
Further, R ³ represents any one selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 18 carbon atoms. ..
Particularly preferably, R ¹ , R ² and R ³ are all methyl groups.
As the above-mentioned glutarimide-based structural unit (B-3), only one type may be used alone, or two or more types may be used in combination.

The content of the glutarimide-based structural unit (B-3) is not particularly limited, and can be appropriately determined in consideration of heat resistance, molding processability, optical properties, and the like.
The content of the glutarimide-based structural unit (B-3) is preferably 1 to 60% by mass, more preferably 3 to 50% by mass, and particularly preferably 3 with the methacrylic resin as 100% by mass. It is ~ 25% by mass.
The content of the glutarimide-based structural unit (B-3) can be calculated, for example, by the method described in [0136] to [0137] of International Publication No. 2015/098096.

The acid value of the resin containing the glutarimide-based structural unit (B-3) is preferably 0.50 mmol / g or less, more preferably 0, in consideration of the balance between the physical properties of the resin, the moldability, the color tone, and the like. It is .45 mmol / g or less.
The acid value can be calculated by, for example, the titration method described in JP-A-2005-23272.

Glutalimide-based structural unit (B-3) is a method of copolymerizing a methacrylic acid ester and / or methacrylic acid and then reacting ammonia or an amine with urea or an unsubstituted urea, methyl methacrylate-methacrylic acid. It can be obtained by a known method such as a method of reacting an acid-styrene copolymer or a methyl methacrylate-styrene copolymer with ammonia or an amine, a method of reacting a polymethacrylic acid anhydride with ammonia or an amine, or the like.
Specific examples thereof include the method described in US Pat. No. 4,246,374 of RM Kopcik.

Further, by imidizing an acid anhydride such as maleic anhydride, a half ester of the acid anhydride and a linear or branched alcohol having 1 to 20 carbon atoms, and an α, β-ethylenically unsaturated carboxylic acid. Also, the above-mentioned glutarimide-based structural unit (B-3) can be formed.

Further, as another preferable preparation method, a (meth) acrylic acid ester and, if necessary, an aromatic vinyl monomer or another vinyl monomer are polymerized, and then an imidization reaction is carried out to carry out the above-mentioned glutar. A method for obtaining a resin containing an imide-based structural unit (B-3) can also be mentioned.
In the step of the imidization reaction, an imidizing agent may be used, and if necessary, a ring closure accelerator may be added. Here, as the imidizing agent, ammonia or a primary amine can be used. As the primary amine, methylamine, ethylamine, n-propylamine, cyclohexylamine and the like can be preferably used.
The method for carrying out the imidization reaction is not particularly limited, and conventionally known methods can be used, and examples thereof include a method using an extruder, a horizontal twin-screw reactor, and a batch reaction tank. The extruder is not particularly limited, and a single-screw extruder, a twin-screw extruder or a multi-screw extruder can be preferably used. More preferably, a tandem type reaction extruder in which two twin-screw extruders are arranged in series can be used.
Further, in producing the above resin, in addition to the step of imidization reaction, an esterification step of treating with an esterifying agent can be included. By including the esterification step, the carboxyl group contained in the resin produced as a by-product during the imidization step can be converted into an ester group, and the acid value of the resin can be adjusted to a desired range. Here, the esterifying agent is not particularly limited as long as the effects of the present application can be exhibited, but dimethyl carbonate and trimethyl acetate can be preferably used. The amount of the esterifying agent used is not particularly limited, but is preferably 0 to 12 parts by mass with respect to 100 parts by mass of the resin. Further, in addition to the esterifying agent, an aliphatic tertiary amine such as trimethylamine, triethylamine, or tributylamine can be used in combination as a catalyst.

[Lactone ring structure unit (B-4)]
The lactone ring structural unit (B-4) constituting the methacrylic resin may be formed after the resin polymerization.
(B-4) As the structural unit, the structural unit represented by the following general formula (7) is preferably used.

In the general formula (7), R ¹ , R ² , and R ³ independently represent a hydrogen atom or an organic group having 1 to 20 carbon atoms. The organic group may contain an oxygen atom.
As the above-mentioned lactone ring structural unit (B-4), only one type may be used alone, or two or more types may be used in combination.

The method for forming the polymer containing the lactone ring structural unit (B-4) is not particularly limited, but a monomer having a hydroxyl group in the side chain, for example, a single amount having a structure represented by the following general formula (8). The obtained copolymer is obtained after copolymerizing a monomer having a compound (2- (hydroxymethyl) methyl acrylate, etc.) and an ester group such as the above-mentioned methacrylic acid ester-based monomer (A). , A method of producing by introducing a lactone ring structure into a polymer by heat treatment in the presence / absence of a predetermined catalyst can be mentioned.

In the general formula (8), R ¹ represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and the alkyl group may be substituted with, for example, a hydroxyl group.
R ² represents a group having 1 to 12 carbon atoms, preferably a hydrocarbon group having 1 to 12 carbon atoms, and the hydrocarbon group may be substituted with, for example, a hydroxyl group.
Particularly preferably, R ¹ is a hydrogen atom and R ² is a methyl group.

Further, as long as the effect of the present invention can be exhibited, the monomer having the structure represented by the general formula (8) may remain unreacted in the methacrylic resin.

The structural units (B) contained in the methacrylic resins described so far include maleimide-based structural units (B-1) and glutarimide-based structural units (B-3) in terms of thermal stability and moldability. It is preferable to include at least one structural unit selected from the group, and more preferably to include a maleimide-based structural unit (B-1).
Among the maleimide-based structural units (B-1), in consideration of availability, it is preferably an N-cyclohexylmaleimide-based structural unit and / or an N-aryl-substituted maleimide-based structural unit, with a small amount of addition. Considering the effect of imparting heat resistance, the N-aryl substituted maleimide-based structural unit is more preferable, and the N-phenylmaleimide-based structural unit is more preferable.

The structural unit (B) having a ring structure in the main chain is contained in the methacrylic resin in an amount of 3 to 30% by mass from the viewpoint of heat resistance, thermal stability, strength and fluidity of the methacrylic resin composition of the present embodiment. It has been. The content of the structural unit (B) having a ring structure in the main chain in the methacrylic resin is preferably 5% by mass or more from the viewpoint of imparting heat resistance and thermal stability to the methacrylic resin composition of the present embodiment. It is more preferably 7% by mass or more, further preferably 8% by mass or more, and particularly preferably 10% by mass or more. Further, from the viewpoint of maintaining the strength and fluidity required for the molded product (particularly the film) in a well-balanced manner, the content of the structural unit (B) having a ring structure in the main chain in the methacrylic resin is preferably 28 mass. % Or less, more preferably 25% by mass or less, still more preferably 22% by mass or less, still more preferably 20% by mass or less, still more preferably 18% by mass or less, and particularly preferably less than 15% by mass.

By including (B) a structural unit having a ring structure in the main chain in the methacrylic resin, thermal decomposition is suppressed and the amount of volatile components generated is reduced when the methacrylic resin is placed in a high temperature environment. Can be done. As a result, the effect of improving the thermal stability of the methacrylic resin can be obtained.

((Other vinyl-based monomer unit (C) copolymerizable with methacrylic acid ester monomer))
As another vinyl-based monomer unit (C) (hereinafter, may be referred to as (C) monomer unit) that can be copolymerized with the methacrylic acid ester monomer constituting the methacrylic resin. , Aromatic vinyl-based monomer unit (C-1), acrylic acid ester monomer unit (C-2), vinyl cyanide-based monomer unit (C-3), and other monomer units ( C-4) can be mentioned.
As the other vinyl-based monomer unit (C) copolymerizable with the methacrylic acid ester monomer, only one type may be used alone, or two or more types may be combined.

The material of the (C) monomer unit can be appropriately selected according to the properties required for the methacrylic resin, but properties such as thermal stability, fluidity, mechanical properties, and chemical resistance are particularly required. If this is the case, select from the group consisting of an aromatic vinyl-based monomer unit (C-1), an acrylic acid ester monomer unit (C-2), and a cyanide vinyl-based monomer unit (C-3). At least one of these is suitable.

[Aromatic vinyl-based monomer unit (C-1)]
In the methacrylic resin, as the (C) monomer unit, a resin having further excellent fluidity can be obtained, and the content of unreacted monomers contained in the methacrylic resin is reduced. A dimer unit (C-1) is preferable.
The monomer forming the aromatic vinyl-based monomer unit (C-1) constituting the methacrylic resin is not particularly limited, but the aromatic vinyl represented by the following general formula (9) is not particularly limited. System monomers are preferred.

In the general formula (9), R ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and the alkyl group may be substituted with, for example, a hydroxyl group.
^R2 is a group consisting of a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 6 to 8 carbon atoms, and an aryloxy group having 6 to 8 carbon atoms. ^R2 may be all the same group or different groups. Further, a ring structure may be formed between R ^2s .
n represents an integer of 0 to 5.

Specific examples of the monomer represented by the above general formula (9) are not particularly limited, but are styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, and 2,4-dimethyl. Styrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, о-ethylstyrene, p-tert-butylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 1,1-diphenylethylene, isopropenylbenzene (α-methylstyrene), isopropenyltoluene, isopropenylethylbenzene, isopropenylpropylbenzene, isopropenylbutylbenzene, isopropenylpentylbenzene, isopropenylhexylbenzene, Examples thereof include isopropenyl octylbenzene.
Among the above, styrene and isopropenylbenzene are preferable, and styrene is more preferable from the viewpoint of imparting fluidity and reducing unreacted monomers by improving the polymerization conversion rate.
These may be appropriately selected depending on the required properties in the methacrylic resin composition of the present embodiment.

When the aromatic vinyl-based monomer unit (C-1) is used, the content is (A) monomer unit and (B) in consideration of the balance between heat resistance, reduction of residual monomer species, and fluidity. When the total amount with the structural unit is 100% by mass, it is preferably 23% by mass or less, more preferably 20% by mass or less, still more preferably 18% by mass or less, still more preferably 15% by mass or less. Even more preferably, it is 10% by mass or less.

When the aromatic vinyl-based monomer unit (C-1) is used in combination with the maleimide-based structural unit (B-1) described above, the (C-1) monomer with respect to the content of the (B-1) structural unit As the ratio (mass ratio) of the content of the unit (that is, (C-1) content / (B-1) content), the processing fluidity at the time of molding the molded body (particularly the film) and the residual From the viewpoint of the effect of reducing silver streaks due to the reduction of monomers, the ratio is preferably 0.3 to 5.
Here, from the viewpoint of maintaining good color tone and heat resistance, the upper limit value is preferably 5, more preferably 3, and even more preferably 1. Further, from the viewpoint of reducing the residual monomer, the lower limit value is preferably 0.3, more preferably 0.4.
As the above-mentioned aromatic vinyl-based monomer (C-1), only one kind may be used alone, or two or more kinds may be used in combination.

[Acrylic acid ester monomer unit (C-2)]
In the methacrylic resin, as the (C) monomer unit, the acrylic acid ester monomer unit (C-2) is preferable from the viewpoint of obtaining a resin having further excellent weather resistance, fluidity, and thermal stability. ..
The monomer forming the acrylic acid ester monomer unit (C-2) constituting the methacrylic acid resin is not particularly limited, but is represented by the following general formula (10). A monomer is preferred.

In the general formula (10), R ¹ represents a hydrogen atom or an alkoxy group having 1 to 12 carbon atoms, and R ² is an alkyl group having 1 to 18 carbon atoms and a cycloalkyl having 1 to 18 carbon atoms. A group represents an aryl group having 1 to 18 carbon atoms.

As the monomer for forming the acrylic acid ester monomer unit (C-2), the methacrylic resin for the molded product of the present embodiment has weather resistance, heat resistance, fluidity, and thermal stability. From the viewpoint of enhancing, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, sec-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate and the like are preferable, and more preferable. , Methyl acrylate, ethyl acrylate, n-butyl acrylate, and from the viewpoint of availability, methyl acrylate and ethyl acrylate are more preferable.
As the acrylic acid ester monomer unit (C-2), only one type may be used alone, or two or more types may be used in combination.

When the acrylic acid ester monomer unit (C-2) is used, the total content of the (A) monomer unit and (B) structural unit is 100 from the viewpoint of heat resistance and thermal stability. In terms of mass%, it is preferably 5% by mass or less, and more preferably 3% by mass or less.

[Vinyl cyanide monomer unit (C-3)]
In the methacrylic resin, the vinyl cyanide-based monomer unit (C-3) is preferable as the (C) monomer unit from the viewpoint of easily obtaining and obtaining a resin having further excellent chemical resistance. ..
The monomer forming the vinyl cyanide-based monomer unit (C-3) constituting the methacrylic resin is not particularly limited, and for example, acrylonitrile, methacrylonitrile, vinylidene cyanide, and the like can be used. Among them, acrylonitrile is preferable from the viewpoint of easy availability and imparting chemical resistance.
As the vinyl cyanide-based monomer unit (C-3), only one type may be used alone, or two or more types may be used in combination.

When the vinyl cyanide-based monomer unit (C-3) is used, the content is the total amount of (A) monomer unit and (B) structural unit from the viewpoint of solvent resistance and heat resistance retention. When is 100% by mass, it is preferably 15% by mass or less, more preferably 12% by mass or less, and further preferably 10% by mass or less.

[Monomer units (C-4) other than (C-1) to (C-3)]
The monomer forming the monomer unit (C-4) other than (C-1) to (C-3) constituting the methacrylic resin is not particularly limited, but for example, acrylamide. Amids such as methacrylic amide; ethylene glycol such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate or both terminal hydroxyl groups of the oligomer. Was esterified with acrylic acid or methacrylic acid; the hydroxyl groups of two alcohols such as neopentyl glycol di (meth) acrylate and di (meth) acrylate were esterified with acrylic acid or methacrylic acid; trimerol propane, Polyhydric alcohol derivatives such as pentaerythritol esterified with acrylic acid or methacrylic acid; polyfunctional monomers such as divinylbenzene and the like can be mentioned.

Among the monomers constituting the above-mentioned (C) monomer unit, at least one selected from the group consisting of methyl acrylate, ethyl acrylate, styrene, and acrylonitrile is preferable from the viewpoint of availability. ..

The content of the other vinyl-based monomer unit (C) copolymerizable with the methacrylic acid ester monomer is 100% by mass of the methacrylic acid-based resin from the viewpoint of enhancing the effect of imparting heat resistance by the structural unit (B). It is preferably 0 to 20% by mass, preferably 0 to 18% by mass, and more preferably 0 to 15% by mass.
In particular, when a crosslinkable polyfunctional (meth) acrylate having a plurality of reactive double bonds is used as the (C) monomer unit, the content of the (C) monomer unit is the fluidity of the polymer. From the viewpoint of the above, it is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and further preferably 0.2% by mass or less.

In particular, from the viewpoint of heat resistance and optical properties of the methacrylic resin, when the total amount of (B) structural unit and (C) monomer unit is 100% by mass, the content of (B) structural unit is It is 45 to 100% by mass. At this time, the content of (C) the structural unit is 0 to 55% by mass. The content of the structural unit (B) is preferably 50 to 100% by mass, more preferably 50 to 90% by mass, and further preferably 50 to 80% by mass.

Hereinafter, the characteristics of the methacrylic resin will be described.

<Glass transition temperature>
The glass transition temperature of the methacrylic resin is not particularly limited, but is preferably 110 ° C. or higher, more preferably 115 ° C. or higher, still more preferably 117 ° C. or higher, and even more preferably 117 ° C. or higher from the viewpoint of sufficiently obtaining heat resistance. Is 120 ° C. or higher, particularly preferably 125 ° C. or higher. Further, it is preferable that the glass transition temperature of the methacrylic resin is high, but if it is too high, it is necessary to raise the molding processing temperature, and if this is the case, bubbles are likely to be generated due to the decomposition of the resin due to heating. The temperature is preferably 160 ° C. or lower, more preferably 155 ° C. or lower, still more preferably 150 ° C. or lower, still more preferably 145 ° C. or lower, and particularly preferably 140 ° C. or lower.
The glass transition temperature can be measured by the midpoint method according to ASTM-D-3418.

<Weight average molecular weight, molecular weight distribution>
The weight average molecular weight (Mw) of the methacrylic resin is preferably 65,000 to 300,000 from the viewpoint of obtaining a methacrylic resin having further excellent mechanical strength, solvent resistance, and fluidity.
By setting the weight average molecular weight of the methacrylic resin in the above range, the methacrylic resin and the methacrylic resin composition of the present embodiment are excellent in mechanical strength such as Charpy impact strength and fluidity. From the viewpoint of maintaining mechanical strength, the weight average molecular weight is preferably 65,000 or more, more preferably 70,000 or more, still more preferably 80,000 or more, still more preferably 100,000 or more. The weight average molecular weight is preferably 250,000 or less, more preferably 230,000 or less, still more preferably 220,000 or less, still more preferably 200,000 or less, and particularly preferably 200,000 or less, from the viewpoint of ensuring fluidity during molding. It is preferably 180,000 or less, and particularly preferably 170,000 or less.
The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the methacrylic resin is preferably 1.5 to 5 in consideration of the balance between fluidity, mechanical strength, and solvent resistance. .. It is more preferably 1.5 to 4.5, still more preferably 1.6 to 4, even more preferably 1.6 to 3, and even more preferably 1.6 to 2.5.
The weight average molecular weight (Mw) and the number average molecular weight (Mn) can be measured by gel permeation chromatography (GPC). Specifically, a standard methacrylic resin whose monodisperse weight average molecular weight, number average molecular weight and peak molecular weight are known in advance and can be obtained as a reagent, and an analytical gel column in which the high molecular weight component is first eluted are used, and the elution time and weight average are used. Create a calibration line from the molecular weight. Next, the weight average molecular weight and the number average molecular weight of the methacrylic resin sample to be measured can be obtained from the obtained calibration curve. Specifically, it can be measured by the method described in Examples described later.

<Ratio of components in a specific molecular weight range>
In the methacrylic resin, the content of the component having a weight average molecular weight of 10,000 or less measured by gel permeation chromatography (GPC) improves the processing fluidity and silver-like marks called silver streaks during molding. From the viewpoint of reducing the appearance defects of the molded product such as, etc., and preventing sticking to the roll during film formation, the content is preferably 0.1 to 5.0% by mass.
By setting the content to 0.1% by mass or more, the processing fluidity can be improved. The lower limit is preferably 0.2% by mass, more preferably 0.5% by mass, and even more preferably 0.6% by mass. Further, by setting the content to 5% by mass or less, it is possible to reduce appearance defects such as reduction of silver streaks during molding, and further to improve mold separation during molding. It is possible to suppress the sticking property to the roll at the time of film formation and suppress the occurrence of cracks when sandwiching the film at the time of stretching. The upper limit is more preferably 4.0% by mass, still more preferably 3.0% by mass, and particularly preferably 2.0% by mass.
The content of the component having a weight average molecular weight of 10,000 or less can be obtained from, for example, the area area ratio obtained from the GPC elution curve. Specifically, in FIG. 1, the starting point of the elution curve is A. When the end point is B, the point on the baseline at the elution time at which the weight average molecular weight is 10,000 is X, and the point on the GPC elution curve is Y, the curve BY, the line segment BX, and the line segment XY are surrounded. The ratio of the area to the area area in the GPC elution curve can be obtained as the content (% by mass) of the component having a weight average molecular weight of 10,000 or less.

In the methacrylic resin, the content of the component having a weight average molecular weight of more than 10,000 and 50,000 or less is preferably 10.0 to 25.0% by mass.
By setting the content to 10.0 to 25.0% by mass, it is possible to suppress the occurrence of streak unevenness during film forming and improve the sticking property to the roll during film forming. The lower limit is more preferably 12.0% by mass, still more preferably 13. It is 0% by mass, and the upper limit is more preferably 24.0% by mass.
The content of the component having a weight average molecular weight of more than 10,000 and 50,000 or less can be determined in the same manner as the content of the component having a weight average molecular weight of 10,000 or less.

In the methacrylic resin, the ratio (b / a) of the content (b) of the component having a weight average molecular weight of more than 50,000 to the content (a) of the component having a weight average molecular weight of more than 10,000 and 50,000 or less. ) Is preferably 2.5 to 8.5 from the viewpoint of improving the balance between thermal stability and processability.
Looking at the abundance ratio of high molecular weight and low molecular weight, if the ratio of low molecular weight is high due to the influence of the viscosity difference between the high molecular weight and low molecular weight during heat processing, the processing fluidity will be affected. Although it is excellent, it tends to have high adhesiveness to the roll during film processing, while when the high molecular weight body ratio is high, streak unevenness tends to occur easily during film processing.
If it is desired to improve the stickability after imparting the characteristics of both in a well-balanced manner, the above ratio is preferably 3.0 or more, more preferably 3.5 or more. On the other hand, when it is desired to further improve the streak unevenness during film processing, the above ratio is preferably 8.0 or less, more preferably 7.5 or less.

The methacrylic resin contains the above-mentioned (A) monomer, (B) monomer constituting a structural unit, (C) a dimer and a trimer obtained by any combination of monomers, and the like. The total content of the specific components is preferably 0.01 to 0.40% by mass from the viewpoint of preventing sticking to the mold or roll during molding and suppressing foaming during film formation.
When the total content of the above components is within this range, the stickability to the mold or the film roll during the molding process can be suppressed, and the formability is improved. Further, if it is less than 0.01% by mass, the process becomes complicated, which is not preferable.
The total content of the above components can be determined by gas chromatography / mass spectrometry (GC / MS) measurement.
As the column preferably used in GC / MS measurement, a non-polar or slightly polar column is preferable, and a column having (5% phenyl) -95% methylpolysiloxane as a stationary phase is more preferable. Specifically, 007-2, CP-Sil 8CB, DB-5, DB-5.625, DB-5ht, HP-5, HP-5ms, OV®-5, PTE-5, PTE- 5QTM, PAS-5, RSL-200, Rtx®-5, Rtx®-5ms, SAC-5, SE®-54, SPB®-5, ULTRA-2, Examples thereof include XTI-5, SE (registered trademark) -52, BP-5, PE-2, ZB-5, AT (registered trademark) -5, EC (registered trademark) -5 and the like.
Examples of the carrier gas preferably used include helium gas. The gas flow rate is preferably about 1 mL / min, and is preferably controlled so as to be constant during the measurement.
The injection amount of the sample is preferably about 1 μL.
When octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate is used as the internal standard, for example, when the peak of the internal standard is detected at a retention time of about 20 minutes, the monomer used. Peaks of components containing seed dimers, trimers and the like are detected at a retention time longer than the retention time of the internal standard. Here, the total content of the above components shall be calculated from the area ratio of both peaks (that is, their abundance ratio) between the detection of the peak of the internal standard substance and the detection of the peak of the above components. Can be done.

(Manufacturing method of methacrylic resin)
The method for producing the methacrylic resin is not particularly limited as long as the above-mentioned methacrylic resin can be obtained.
The methacrylic resin can be copolymerized with the methacrylic ester monomer unit (A), the structural unit (B) having a ring structure in the main chain, and, if necessary, the methacrylic ester monomer described above. Each monomer for forming the other vinyl-based monomer unit (C) can be produced by a bulk polymerization method, a solution polymerization method, a suspension polymerization method, a precipitation polymerization method, or an emulsion polymerization method. For the production of the methacrylic resin, a bulk polymerization method or a solution polymerization method is preferably used, and a solution polymerization method is more preferably used.
Further, the methacrylic resin may be produced by a continuous type or a batch type.
Then, in the method for producing a methacrylic resin, it is preferable to polymerize the monomer by radical polymerization.

Hereinafter, as an example of a method for producing a methacrylic resin, a case of producing by radical polymerization in a batch system using a solution polymerization method will be specifically described.
An example of a method for producing a methacrylic resin is a compounding step in which a monomer and an organic solvent are added to the reactor, and a polymerization initiator is added to the reactor to carry out a polymerization reaction of the monomer. It comprises a polymerization step to be carried out and, if necessary, a devolatile step of removing an organic solvent and unreacted monomers.

((Mixing process))
In an example of the method for producing a methacrylic resin, first, a monomer that can form a methacrylic acid ester monomer unit (A) and a single amount that can form a structural unit (B) having a ring structure in the main chain. The body, if necessary, further prepares a monomer that can form another vinyl-based monomer unit (C) copolymerizable with the methacrylic acid ester monomer, and an organic solvent in a reactor (preparation). Process).

-Monomer-
The monomer is as described for each of the monomer units (A) to (C) in the methacrylic resin.
A polymerization inhibitor may remain in the monomer used as long as it does not excessively interfere with the polymerization reaction, and the content of the remaining polymerization inhibitor is determined from the viewpoint of polymerization reactivity and handleability. The total amount of the monomers is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less.

-Organic solvent-
The organic solvent used arbitrarily is preferably a good solvent for the methacrylic resin in consideration of the removal efficiency in the devolatilization step (described later) for removing the monomer remaining in the methacrylic resin. ..
The solubility parameter δ of the organic solvent is preferably 7.0 to 12.0 (cal / cm ³ ) ^1/2 , more preferably 8 in consideration of the solubility of the copolymer constituting the methacrylic resin. It is 0.0 to 11.0 (cal / cm ³ ) ^1/2 , more preferably 8.2 to 10.5 (cal / cm ³ ) ^1/2 .
The method for determining the value of the solubility parameter δ is described in, for example, P76-P118 in the non-patent document "Journal of Paint Technology Vol. 42, No. 541, February 1970". L. Hoy, "New Values of the Solubility Parameters From Vapor Pressure Data", J. Mol. Brandrup et al., "Polymer Handbook Fourth Edition" P-VII / 675-P714 and the like can be referred to.
In addition, 1 (cal / cm ³ ) ^1/2 is about 0.489 (MPa) ^1/2 .
Specific examples of the organic solvent include aromatic hydrocarbons such as toluene, xylene, ethylbenzene and mesitylene; alicyclic hydrocarbons such as cyclohexane, methylcyclohexane and decalin; and ketone solvents such as methylethylketone and methylisobutylketone. ..

Further, as the organic solvent, an organic solvent recovered in the devolatile step after polymerization can also be used.
If the recovered organic solvent contains an unreacted monomer component, analyze the content of the unreacted monomer contained in the organic solvent, and then analyze the required amount of the unreacted monomer component. Formulations can also be made by adding bodies.

The amount of the organic solvent used in the polymerization step of the methacrylic resin is preferably an amount that can be easily removed without causing precipitation of the copolymer or the used monomer during the production due to the progress of the polymerization.
When the methacrylic resin is polymerized by the solution polymerization method, the amount of the organic solvent to be blended is specifically 10 to 200 parts by mass when the total amount of all the monomers to be blended is 100 parts by mass. Is preferable. It is more preferably 25 to 200 parts by mass, still more preferably 50 to 200 parts by mass, and even more preferably 50 to 150 parts by mass.

-Reactor-
The reactor may be appropriately selected in consideration of the amount of material and the size required from the viewpoint of heat removal.
The L / D of the reactor is preferably 0.5 to 50, more preferably 1 to 25, and even more preferably 1 to 10 from the viewpoint of the stirring efficiency of the polymerization reaction solution.

Further, the amount of the monomer and / or the organic solvent to be provided to the reactor is not particularly problematic as long as the heat can be sufficiently removed, and the polymerization may be carried out with a full liquid, and 50 to 99% of the amount in the reactor is charged. It may be polymerized in an amount. Further, it may be refluxed at the time of polymerization.

It is preferable that the reactor is equipped with a stirrer, and examples of the stirrer to be used include inclined paddle blades, flat paddle blades, propeller blades, anchor blades, Faudler blades (retreat blades), and turbine blades. , Bull margin wing, Max blend wing, Full zone wing, Ribbon wing, Super mix wing, Intermig wing, Special wing, Axial flow wing, etc. Full zone blades are preferably used.

The stirring speed at the time of polymerization depends on the type of stirring device used, the stirring efficiency of the stirring blade, the capacity of the polymerization tank, etc., but both the low viscosity state at the initial stage of polymerization and the high viscosity state at the late stage of polymerization are sufficiently stirred and mixed. The speed may be as long as possible, and in consideration of polymerization stability, it is preferably about 1 to 500 rpm.

The method for introducing each monomer into the reactor is not particularly limited as long as the effects of the present invention can be obtained, and even if they are mixed in advance and introduced into the reactor, they are separately introduced into the reactor. May be good. Considering productivity and handleability, it is preferable to mix some or all of the monomers in advance and then introduce them into the reactor.
In particular, when mixing in advance, some or all of the organic solvents that can be used in the polymerization can be mixed at the same time. When using an organic solvent, it is preferable to use one that can dissolve the monomer to be polymerized, and the solubility parameter δ of the organic solvent is 7.0 to 12.0 (cal / cm ³ ). It is preferably ^1/2 .

In the compounding step, as long as the effect of the present invention can be exhibited, a molecular weight adjusting agent and other additives (also used in the polymerization step described later) are added in addition to the monomer and the organic solvent, if necessary. , Can be added in advance.

((Polymerization step))
In one example of the method for producing a methacrylic resin, a polymerization initiator,, if necessary, a molecular weight modifier, other additives, and additional monomers are then added to the reactor after the compounding step. Polymerization reaction of the polymer is carried out (polymerization step).

In this step, the polymerization reaction of the monomer is started by the start of addition of the polymerization initiator.
The polymerization initiator may be added to the reactor after being dissolved in an additional monomer and / or an additional organic solvent.

-Initiator-
The polymerization initiator may be any as long as it decomposes at the polymerization temperature to generate active radicals, but it is necessary to achieve the required polymerization conversion rate within the residence time, and the half-life at the polymerization temperature is 0. A polymerization initiator is selected that satisfies .6 to 60 minutes, preferably 1 to 30 minutes. However, even for an initiator having a half-life of more than 60 minutes at the polymerization temperature, it can be used as a polymerization initiator that generates an amount of active radicals suitable for the present embodiment by adding a predetermined amount in a batch or in a time of about 10 minutes. can do. In order to achieve the required polymerization conversion rate in that case, a polymerization initiator having a half-life of 60 to 1800 minutes, preferably 260 to 900 minutes at the polymerization temperature is selected.
The polymerization initiator preferably used can be appropriately selected in consideration of the polymerization temperature and the polymerization time. For example, Nippon Oil & Fats Co., Ltd. "Organic Peroxide" Material 13th Edition, Atchem Yoshitomi Co., Ltd. Technical Data And the initiator described in "Azo Polymerization Initiators" of Wako Pure Chemical Industries, Ltd. and the like can be preferably used, and the above-mentioned half-life can be easily determined by the various constants described.
The polymerization initiator is not limited to the following when radical polymerization is performed, and for example, di-t-butyl peroxide, lauroyl peroxide, stearyl peroxide, benzoyl peroxide, and t-butyl peroxide. Oxyneodecanate, t-butylperoxypivalate, dilauroyl peroxide, dicumyl peroxide, t-butylperoxy-2-ethylhexanoate, 1,1-bis (t-butylperoxy) -3 , 3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane (eg, perhexa® C), acetyl peroxide, capriel peroxide, 2,4-dichlorobenzoyl peroxide , Isobutyl peroxide, acetylcyclohexylsulfonyl peroxide, t-butylperoxyvipalate, t-butylperoxy-2-ethylhexanoate, iso-propylperoxydicarbonate, iso-butylperoxydicarbonate, sec- Butyl peroxydicarbonate, n-butylperoxydicarbonate, 2-ethylhexyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, t-amylperoxy-2-ethylhexanoate, 1 , 1,3,3-Tetramethylbutylperoxyethyl hexanoate, 1,1,2-trimethylpropylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di (t-butyl) Peroxy) hexane (eg, Perhexa® 25B), t-butylperoxyisopropyl monocarbonate, t-amylperoxyisopropyl monocarbonate, 1,1,3,3-tetramethylbutylperoxyisopropyl monocarbonate, 1,1,2-trimethylpropylperoxyisopropyl monocarbonate, 1,1,3,3-tetramethylbutylperoxyisononaate, 1,1,2-trimethylpropylperoxy-isononaate, t-butylperoxybenzoate Organic peroxides such as azobisisobutyronitrile, azobisisovaleronitrile, azobisdimethylvaleronitrile, azobiscyclohexanenitrile, 1,1-azobis (1-cyclohexanecarbonitrile), 2,2'- Azobis-4-methoxy-2,4-azobisisobutyronitrile, 2,2'-azobis -2,4-dimethylvaleronitrile, 2,2'-azobis-2-methylbutyronitrile, 1,1'-azobis (1-acetoxy-1-phenylethane), dimethyl-2,2'-azobisiso Examples thereof include general radical polymerization initiators such as azo compounds such as butyrate and 4,4'-azobis-4-cyanovaleric acid.
A combination of these radical polymerization initiators and an appropriate reducing agent may be used as a redox-based initiator.
These polymerization initiators can be used alone or in combination of two or more.

The polymerization initiator may be added in an amount necessary for obtaining a desired polymerization rate in the polymerization reactor.
In the polymerization reaction, the degree of polymerization can be increased by increasing the supply amount of the polymerization initiator, but by using a large amount of the initiator, the overall molecular weight tends to decrease and the calorific value during polymerization increases. Therefore, the polymerization stability may decrease due to overheating.
From the viewpoint of facilitating the acquisition of a desired molecular weight and ensuring polymerization stability, the polymerization initiator is preferably used in the range of 0 to 1 part by mass with respect to 100 parts by mass of the total amount of all the monomers used. , More preferably 0.001 to 0.8 parts by mass, and more preferably 0.01 to 0.5 parts by mass. The amount of the polymerization initiator added can be appropriately selected in consideration of the temperature at which the polymerization is carried out and the half-life of the initiator.

In the method for producing a methacrylic resin, (a) from the viewpoint of suppressing the amount of oligomers (for example, dimers and trimers) and low molecular weight (for example, 500 to 10,000 by weight average molecular weight) produced in the late stage of polymerization. Optimal amount of radicals in the polymerization reaction system from the viewpoints of (b) increasing the polymerization conversion rate, (c) increasing the molecular weight of the obtained methacrylic resin, and (d) stabilizing the polymerization by suppressing overheating during polymerization. Is preferable.
More specifically, the type of initiator, the amount of initiator, and the polymerization temperature so that the ratio of the total amount of radicals generated by the polymerization initiator to the total amount of unreacted monomers remaining in the reaction system is always equal to or less than a certain value. Etc. are preferably selected as appropriate.

Hereinafter, a method for adding a suitable polymerization initiator in the polymerization step will be described.
According to such a method, by controlling the amount of radicals generated during polymerization, the total amount of components in the methacrylic resin and the amount of components having a weight average molecular weight of 10,000 or less can be set in a desired range.

In the method for producing a methacrylic resin, the total time from the start of addition of the polymerization initiator to the end of addition is defined as B time, and the polymerization initiator is at least once within 0.5 × B hours from the start of addition of the polymerization initiator. It is preferable that the addition amount per unit time is smaller than the addition amount per unit time at the start of addition (condition (i)).

Here, in particular, from the viewpoint of optimizing the radical concentration, it is preferable to gradually reduce the addition rate.

Further, in the method for producing a methacrylic resin, in addition to the above condition (i), per unit time of the polymerization initiator is between 0.01 × B and 0.3 × B hours from the start of addition of the polymerization initiator. The addition amount of is preferably 70% or less (condition (ii)) of the addition amount per unit time at the start of addition, more preferably 60% or less, still more preferably 50% or less. , 40% or less is particularly preferable.
For example, when the addition rate (addition amount per unit time) of the polymerization initiator at the start of polymerization is 100 ppm / hour, and the B time, which is the total time from the start of addition of the polymerization initiator to the end of addition, is 10 hours. In addition, the addition rate (addition amount per unit time) is preferably 70 ppm / hour or less within 0.1 to 3 hours from the start of addition of the polymerization initiator.
When a fixed amount of the polymerization initiator is added at the start of the polymerization and then the quantitative feed is performed, the above condition (ii) is not satisfied. For example, if 1/3 of the required initiator is added all at once and then the remaining 2/3 is added over a certain period of time (for example, 3 hours), the polymerization initiator is added from the start. The addition amount is changed in 0 hours, and the above condition (ii) is not satisfied.

More preferably, in the method for producing a methacrylic resin, in addition to the above, the amount of the polymerization initiator per unit time between 0.01 × B and 0.3 × B hours from the start of addition of the polymerization initiator. The average amount of the polymerization initiator added is preferably 70% or less, preferably 60% or less, of the average amount of the polymerization initiator added per unit time from the start of addition of the polymerization initiator to 0.01 × B hours. It is more preferably 50% or less, and particularly preferably 40% or less.

In the method for producing a methacrylic resin, in addition to the above condition (i), the amount of the polymerization initiator per unit time is between 0.7 × B and 1.0 × B hours from the start of addition of the polymerization initiator. The addition amount is preferably 25% or less per unit time at the start of addition (condition (iii)), more preferably 20% or less, still more preferably 18% or less.
For example, when the addition rate (addition amount per unit time) of the polymerization initiator at the start of polymerization is 100 ppm / hour, and the B time, which is the total time from the start of addition of the polymerization initiator to the end of addition, is 10 hours. In addition, the addition rate (addition amount per unit time) is preferably 25 ppm / hour or less within 7 to 10 hours from the start of addition of the polymerization initiator.

More preferably, in the method for producing a methacrylic resin, in addition to the above, the amount of the polymerization initiator added per unit time between 0.7 × B and 1.0 × B hours from the start of addition of the polymerization initiator. The average of the above is preferably 25% or less, preferably 20% or less, which is 25% or less of the average amount of the polymerization initiator added per unit time from the start of addition of the polymerization initiator to 0.01 × B hours. It is more preferably 18% or less, further preferably 18% or less.

It is more preferable that the above condition (ii) and the condition (iii) are adopted in combination.

Further, in the method for producing a methacrylic resin, in addition to the above condition (i), the amount of the polymerization initiator added during the period of 0.5 × B to 1.0 × B from the start of the addition of the polymerization initiator is set. The total amount of the initiator added is preferably 20 to 80% by mass (condition (iv)), more preferably 20 to 70% by mass, and 20 to 60% by mass. More preferred.

Further, in the method for producing a methacrylic resin, in addition to the above condition (i), the polymerization reaction time for carrying out the polymerization reaction of the monomer is set to 1.0 × B to 5.0 × B time (condition (condition (condition)). v)) is preferable, 1.0 × B to 4.5 × B time is more preferable, and 1.0 × B to 4.0 × B time is further preferable.

It is more preferable that the above condition (iv) and the condition (v) are adopted in combination.

In any of the above cases (i) to (v), as a method of supplying the polymerization initiator, it is previously dissolved in the monomer and / or the organic solvent used in the polymerization reaction from the viewpoint of supply stability. It is preferable to supply the mixture after allowing it to be supplied. The monomer and / or organic solvent used is preferably the same as that used in the polymerization reaction. Further, from the viewpoint of avoiding blockage in the polymerization pipe, it is more preferable that the polymerization initiator is dissolved in an organic solvent and supplied.

-Molecular weight adjuster-
Examples of the molecular weight adjusting agent used arbitrarily include a chain transfer agent, an inifata, and the like.
In the process for producing a methacrylic resin contained in the methacrylic resin composition of the present embodiment, the molecular weight of the polymer to be produced can be controlled within a range that does not impair the object of the present invention.
As the chain transfer agent and the inifata, for example, a chain transfer agent such as alkyl mercaptans, dimethylacetamide, dimethylformamide, triethylamine, etc.; Control can be performed, and further, the molecular weight can be controlled by adjusting the amount of these chain transfer agents and inifatas added.

When these chain transfer agents and inifatas are used, alkyl mercaptans are preferably used from the viewpoint of handleability and stability, and are not limited to the following, for example, n-butyl mercaptan and n-octyl mercaptan. , N-dodecyl mercaptan, t-dodecyl mercaptan, n-tetradecyl mercaptan, n-octadecyl mercaptan, 2-ethylhexyl thioglycolate, ethylene glycol dithioglycolate, trimethylol propanthris (thioglycolate), pentaerythritol tetrakis (thioglycolate) ) Etc. can be mentioned.
These molecular weight adjusting agents can be appropriately added according to the required molecular weight, but generally, they are in the range of 0.001 to 3 parts by mass with respect to 100 parts by mass of the total amount of all the monomers used. Used.
In addition, other methods for controlling the molecular weight include a method of changing the polymerization method, a method of adjusting the amount of the polymerization initiator, a method of changing the polymerization temperature, and the like.
As these molecular weight control methods, only one kind of method may be used alone, or two or more kinds of methods may be used in combination.

In the methacrylic resin, a chain transfer agent (molecular weight adjuster) may be used for the purpose of adjusting the molecular weight or improving the thermal stability of the polymer, and the chain transfer agent to be used may be used. The type and method of use are not limited as long as the effects of the present invention can be exhibited.
In the methacrylic resin, it is necessary to control the total amount of the components including the dimer and the trimer to an appropriate amount, and from the viewpoint of controlling the amount of the component having a weight average molecular weight of 10,000 or less to an appropriate amount, the polymerization reaction system. It is preferable to select a method so that the amount of the remaining chain transfer agent does not become excessive with respect to the amount of the remaining monomer.
Examples of the method for supplying the chain transfer agent include a method in which the chain transfer agent is dissolved in a monomer in advance, a method in which the chain transfer agent is added all at once and / or sequentially at a stage where the degree of polymerization is 50% or less, and a method in which the degree of polymerization is up to 90%. A method such as a method of gradually reducing the amount of the chain transfer agent to be added can be preferably used by a method of adding the chain transfer agent in a batch and / or continuously.

-Other additives-
Other additives used arbitrarily are not particularly limited as long as the effects of the present invention can be exhibited, and may be appropriately selected depending on the intended purpose.

The dissolved oxygen concentration in the polymerization solution in the polymerization step is not particularly limited, but is preferably 10 ppm or less.
The dissolved oxygen concentration can be measured using, for example, a dissolved oxygen meter DO meter B-505 (manufactured by Iijima Denshi Kogyo Co., Ltd.).
As a method for reducing the dissolved oxygen concentration, the method of bubbling the inert gas in the polymerization solution and the operation of pressurizing the inside of the container containing the polymerization solution with the inert gas to about 0.2 MPa and then releasing the pressure are repeated before the polymerization. Examples thereof include a method and a method of passing an inert gas into a container containing a polymerization solution.

When the methacrylic resin is produced by solution polymerization, the polymerization temperature is not particularly limited as long as the polymerization proceeds, but from the viewpoint of productivity, it is preferably 50 to 200 ° C., more preferably 80 to 200 ° C. ° C., more preferably 80 to 180 ° C., even more preferably 80 to 160 ° C., and particularly preferably 90 to 160 ° C.

The polymerization reaction time is not particularly limited as long as the required degree of polymerization can be obtained, but is preferably 0.5 to 15 hours, more preferably 1 to 12 hours from the viewpoint of productivity and the like. It is time, more preferably 1 to 10 hours.
The polymerization reaction time is the time from the start of addition of the polymerization initiator to the termination of the polymerization reaction, or from the start of addition of the polymerization initiator to the start of removal of the polymerization reaction solution from the reactor. Say time.

As a method for terminating the polymerization reaction of the monomer in the polymerization step, a known method may be appropriately selected according to the reaction system.

((Devolatile process))
From the polymerization reaction product extracted from the polymerization reactor, the organic solvent and the unreacted monomer can be removed by using a devolatilizer. The removed solvent may be reused in the polymerization reaction after performing a rectification operation.
The devolatilization device that can be preferably used may be any device that can heat-treat the polymerization reaction product at a temperature of 150 to 320 ° C. and separate and recover the volatile matter.
Examples thereof include an extruder having one or a plurality of vent openings, an SC processor, a KRC kneader, a vacuum decompression tank with a gear pump, a thin film evaporator for high viscosity EXEVA, a flash drum and the like.
The above-mentioned devolatilization device can be used alone or in combination of two or more kinds of devices.
In the devolatile step, the total amount of residual volatile content contained in the devolatile resin is preferably 1% by mass or less.

The methacrylic resin can be produced by the production method described above.

(Methyl methacrylic resin composition)
The methacrylic resin composition of the present embodiment is characterized by containing the above-mentioned methacrylic resin, and in addition to this, optionally, other rubbery polymers and resins other than the methacrylic resin described later. It may contain a resin, an additive, or the like. Further, it may contain 100% by mass of the above-mentioned methacrylic resin without containing these optional components, that is, it may consist of only the methacrylic resin. The methacrylic resin composition of the present embodiment is not particularly limited, but from the viewpoint of improving various physical properties described later, the above-mentioned methacrylic resin is preferably 95% by mass or more, more preferably 97% by mass or more, still more preferable. Contains 99% by mass or more, particularly preferably 99.5% by mass or more.
Further, the methacrylic resin composition of the present embodiment is characterized in that it has a glass transition temperature of 110 to 160 ° C. and contains 100 or less foreign substances having a particle size of 10 μm or more and less than 20 μm as measured by a particle counter. And.

-Rubber polymer-
The rubbery polymer may be contained in the methacrylic resin composition of the present embodiment in a range not exceeding 3.5 parts by mass with respect to 100 parts by mass of the methacrylic resin. By containing a rubbery polymer of preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 1.5 parts by mass or more, the film suppresses sticking to the roll during film molding. The effect of rubber is obtained. By containing a rubbery polymer of 3.5 parts by mass or less, preferably 3.0 parts by mass or less, the optical properties of the resin can be maintained.

The rubbery polymer is not particularly limited as long as it can exhibit the above effects, and known materials can be used.
For example, rubber particles having a multilayer structure such as general butadiene-based ABS rubber, acrylic-based, polyolefin-based, silicone-based, and fluororubber can be used.
When high transparency is required in the molded product of the present embodiment, a rubbery polymer having a refractive index close to that of the above-mentioned methacrylic resin can be preferably used, and an acrylic rubbery polymer is particularly preferable. Can be used.

The rubbery polymer preferably used in the present embodiment is not limited to the following, but for example, the acrylic rubbery polymers proposed in Examples 1 to 3 below may be applied. Can be done.

-Example 1: Rubber polymer disclosed in Japanese Patent Publication No. 60-17406-
The rubbery polymer of Example 1 is a multilayer structure particle produced by the following steps (A) to (C).
(A) Step: A dispersion liquid of a polymer mainly composed of methyl methacrylate having a glass transition point of 25 ° C. or higher by emulsion polymerization of methyl methacrylate alone or a mixture of methyl methacrylate and a monomer copolymerizable therewith. First layer forming step to obtain.
Step (B): An alkyl acrylate that forms a copolymer having a glass transition point of 25 ° C. or lower when polymerized on the product obtained by the step (A), and a monomer copolymerizable with the alkyl acrylate. A second layer step in which a mixture containing a polyfunctional cross-linking agent and a polyfunctional grafting agent in an amount of 0.1 to 5% by mass based on the total weight of the mixture is added and emulsified and polymerized.
Step (C): A chain of methyl methacrylate or a monomer mixture mainly composed of methyl methacrylate, which forms a polymer having a glass transition point of 25 ° C. or higher when polymerized on the product obtained by the step (B). A third layer forming step in which the transferant is gradually increased and emulsion-polymerized in multiple stages.
The multilayer structure particles are multilayer structure particles made of acrylic rubber in which the molecular weight of the third layer gradually decreases from the inside to the outside.

-Example 2: Rubber polymer disclosed in JP-A-8-245854-
The rubbery polymer of Example 2 is the following acrylic multilayer structure polymer powder.
In this acrylic multilayer structure polymer powder, the melting start temperature of the polymer is 235 ° C. or higher. The inner layer contains a polymer having a glass transition temperature Tg of 25 ° C. or lower when polymerized alone, and the inner layer is at least one soft polymer layer. The outermost layer is a hard polymer layer containing a polymer having a Tg of 50 ° C. or higher when polymerized alone.
The rubber polymer of Example 2 is an acrylic multilayer structure polymer powder containing a coagulation powder obtained by coagulating an emulsified latex of an acrylic multilayer structure polymer, and is a fine powder having a particle size of 212 μm or less of the coagulated powder after drying. The ratio is 40% by mass, and the void volume having a pore size of 5 μm or less as measured by the mercury intrusion method of the coagulated powder after drying is 0.7 cc or less per unit area.

-Example 3: A rubbery polymer disclosed in Japanese Patent Publication No. 7-6318-
The rubbery polymer of Example 3 is a multilayer structure acrylic polymer satisfying the following requirements (a) to (g).
That is, the multilayer structure acrylic polymer is
(A) Methyl methacrylate 90 to 99% by mass, an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms to 1 to 10% by mass, and an α, β-unsaturated carboxylic acid copolymerizable with these, allyl, methallyl, or clothi. 25-45 mass of innermost hard layer polymer obtained by polymerizing a monomer mixture consisting of 0.01 to 0.3% by mass of a graft-binding monomer composed of at least one selected from the group consisting of ruesters. %When,
(B) In the presence of the innermost hard layer polymer, n-butyl acrylate 70 to 90% by mass, styrene 10 to 30% by mass, and α, β-unsaturated carboxylic acids allyl and metharyl that can be copolymerized with these. Alternatively, the soft layer polymer obtained by polymerizing a monomer mixture consisting of 1.5 to 3.0% by mass of a graft-binding monomer composed of at least one selected from the group consisting of crotyl esters is 35 to 45 mass by mass. %When,
(C) In the presence of the innermost hard layer polymer and the soft layer polymer, 90 to 99% by mass of methyl methacrylate and 1 to 10% by mass of a monomer having an alkyl group having 1 to 8 carbon atoms. It is composed of 20 to 30% by mass of the outermost hard layer polymer obtained by polymerizing the mixture.
(D) The weight ratio of the soft layer polymer / (innermost hard layer polymer + soft layer polymer) is 0.45 to 0.57.
(E) A multi-layer acrylic polymer having an average particle size of 0.2 to 0.3 μm, and the multi-layer acrylic polymer is further separated by acetone.
(F) The graft ratio is 20 to 40% by mass, and the graft ratio is 20 to 40% by mass.
(G) A multi-layer acrylic polymer having a tensile elastic modulus of 1000 to 4000 kg / cm ² of the acetone-insoluble portion.

Other examples of the rubbery polymer include the following particles.
For example, Japanese Patent Publication No. 55-27576, Japanese Patent Publication No. 58-1694, Japanese Patent Publication No. 59-36645, Japanese Patent Publication No. 59-36646, Japanese Patent Publication No. 62-41241, Japanese Patent Application Laid-Open No. 59-20221. , JP-A-63-27516, JP-A-51-129449, JP-A-52-56150, JP-A-50-124647, etc., Acrylic rubber having a 3- to 4-layer structure. Particles and the like can also be used.

The rubbery polymer contained in the methacrylic resin composition of the present embodiment preferably has a multilayer structure.
When the rubbery polymer has a multi-layer structure, the larger the number of layers of the rubbery polymer, the more the elasticity can be controlled in a suitable range, but the rubbery polymer is contained. Considering the color tone of the molded product in the case, the particles having a three-layer structure or more are preferable, and the acrylic rubber particles having a three-layer structure or more are more preferable.
By using the rubber particles having the above three-layer structure or more as the rubber polymer, heat deterioration during the molding process of the molded product of the present embodiment and deformation of the rubber polymer due to heating are suppressed, and the heat resistance of the molded product is suppressed. There is a tendency for sex and transparency to be maintained.

A rubbery polymer having a three-layer structure or more refers to rubber particles having a structure in which a soft layer made of a rubber-like polymer and a hard layer made of a glassy polymer are laminated, and is a hard layer (first layer) -soft layer from the inside. Preferred examples include particles having a three-layer structure formed in the order of (second layer) -hard layer (third layer).
Having a hard layer in the innermost layer and the outermost layer tends to suppress deformation of the rubbery polymer, and having a soft component in the central layer tends to impart good toughness.

The rubbery polymer composed of three layers can be formed, for example, by a multilayer structure graft copolymer. The multilayer structure graft copolymer can be produced, for example, by using methyl methacrylate and a monomer copolymerizable with the methyl methacrylate.
The monomer copolymerizable with the methyl methacrylate is not limited to the following, and for example, known (meth) acrylic acid, (meth) acrylate other than methyl methacrylate, styrene, α-methyl styrene and the like. Monofunctional monomer, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, triallyl Examples thereof include polyfunctional monomers such as isocyanurate, diallyl maleate, and divinylbenzene.
The above-mentioned monomers may be used alone or in combination of two or more, if necessary.

Specifically, when the rubbery polymer has a three-layer structure, the copolymer forming the innermost layer has 65 to 90% by mass of methyl methacrylate and other copolymerizable properties thereof. It is preferably a copolymer using 10 to 35% by mass of the monomer.
From the viewpoint of appropriately controlling the refractive index of the copolymer, the other copolymerizable monomer copolymerizable with the methyl methacrylate is 0.1 to 5% by mass of the acrylic acid ester monomer. , 5 to 35% by mass of the aromatic vinyl compound monomer and 0.01 to 5% by mass of the copolymerizable polyfunctional monomer are preferable.
The acrylic acid ester monomer (forming the innermost layer in the copolymer) is not particularly limited, but for example, n-butyl acrylate and 2-hexyl acrylate are preferable.
As the aromatic vinyl compound monomer, the same monomer as that used for the methacrylic resin can be used, but preferably, the refractive index of the innermost layer is adjusted to adjust the refractive index of the innermost layer to form the molded product of the present embodiment. Styrene or a derivative thereof is used from the viewpoint of improving the transparency of the material.
The copolymerizable polyfunctional monomer is not particularly limited, but is preferably ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1, Examples thereof include 4-butanediol di (meth) acrylate, allyl (meth) acrylate, triallyl isocyanurate, diallyl maleate, and divinylbenzene. These may be used alone or in combination of two or more. Of these, allyl (meth) acrylate is more preferred.

The second layer of the rubbery polymer composed of three layers, that is, the soft layer, is a rubber-like copolymer exhibiting rubber elasticity and is important for imparting excellent impact strength to the molded product.
The second layer is preferably formed from, for example, a copolymer of an alkyl acrylate and a monomer copolymerizable with the alkyl acrylate, or a polymer of a copolymerizable polyfunctional monomer.
The alkyl acrylate is not particularly limited, and examples thereof include methyl acrylate, ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate. These can be used alone or in combination of two or more, and in particular, n-butyl acrylate and 2-ethylhexyl acrylate are preferable.
Further, the other monomer copolymerizable with these alkyl acrylates is not particularly limited, and a general monomer can be used, but the refractive index of the second layer is adjusted to adjust the refractive index of the methacrylic resin. Styrene or a derivative thereof is preferably used from the viewpoint of improving the transparency by adjusting to the above.
The copolymerizable polyfunctional monomer is not particularly limited, but is preferably ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1, Examples thereof include 4-butanediol di (meth) acrylate, allyl (meth) acrylate, triallyl isocyanurate, diallyl maleate, and divinylbenzene. These may be used alone or in combination of two or more.

When the rubbery polymer has a three-layer structure, the outermost layer contains 70 to 100% by mass of methyl methacrylate and 0 to 30% by mass of another copolymerizable monomer copolymerizable therewith. It is preferably formed of a copolymer.
The other copolymerizable monomer copolymerizable with the methyl methacrylate forming the outermost layer is not particularly limited, and examples thereof include n-butyl acrylate and 2-hexyl acrylate. ..

When the rubbery polymer is composed of three layers, the rubbery polymer may contain a rubbery polymer having a crosslinked structure, and the rubbery polymer having the crosslinked structure is contained in the second layer. It is preferable that the rubber is used.
The rubber-like polymer is obtained by copolymerizing a polyfunctional monomer, and a crosslinked structure can be formed in the polymer. The crosslinked structure in the rubbery polymer imparts appropriate rubber elasticity and can retain its form in a dispersed state without being dissolved in the monomer mixture.
As the polyfunctional monomer for forming the crosslinked structure, a compound copolymerizable with methyl methacrylate and methyl acrylate can be used.
The amount of the polyfunctional monomer used is preferably 0.1 to 5% by mass with respect to the entire second layer. When the amount used is 0.1% by mass or more, a sufficient cross-linking effect can be obtained, and when it is 5% by mass or less, an appropriate cross-linking strength and an excellent rubber elastic effect can be obtained. Further, when the amount of the polyfunctional monomer used is 0.1% by mass or more, the rubber-like polymer does not melt or swell even when the cast polymerization step is carried out, and the form of the rubber-like elastic body is formed. Can be retained.

Further, for the second layer, it is preferable to use a polyfunctional graft agent for forming a graft bond that makes the affinity with the polymer of the third layer described later close.
The polyfunctional graft agent is a polyfunctional monomer having a different functional group, and is not limited to the following, and examples thereof include allyl esters such as acrylic acid, methacrylic acid, maleic acid, and fumaric acid. Of these, allyl acrylates and allyl methacrylates are preferable.
The amount of the polyfunctional grafting agent used is preferably in the range of 0.1 to 3% by mass with respect to the entire second layer. When the amount of the polyfunctional grafting agent used is 0.1% by mass or more, a sufficient grafting effect can be obtained, and when it is 3% by mass or less, a decrease in rubber elasticity can be prevented.

In the polymerization of the third layer (outermost layer), the molecular weight can be adjusted by using a chain transfer agent in order to improve the affinity with the methacrylic resin.

Further, in order to improve the transparency of the molded product of the present embodiment, it is necessary to match the refractive indexes of the dispersed rubber polymer and the methacrylic resin. However, as described above, when alkyl acrylate is used as a main component in the second layer, it is extremely difficult to completely match the refractive index of the second layer with the methacrylic resin. In order to match the refractive index, for example, when the alkyl acrylate and styrene or a derivative thereof are copolymerized in the second layer, the refractive index becomes substantially equal in a certain temperature region and the transparency is improved, but when the temperature is changed, The refractive index shifts and the transparency deteriorates.
As a means for avoiding this, there is a method of providing a first layer having a refractive index almost the same as that of the methacrylic resin. Further, reducing the thickness of the second layer is also an effective method for preventing the deterioration of the transparency of the molded product of the present embodiment.

The average particle size of the rubbery polymer is 0.03 to 1 μm from the viewpoint of imparting impact strength to the molded product of the present embodiment, from the viewpoint of surface smoothness, and from the viewpoint of obtaining a desired film thickness of the molded product. It is preferably 0.05 to 0.7 μm, still more preferably 0.05 to 0.5 μm, even more preferably 0.05 to 0.4 μm, and even more preferably 0.05 to 0. It is 3 μm.
When the average particle size of the rubbery polymer is 0.03 μm or more, sufficient impact strength tends to be obtained in the molded product of the present embodiment, and when it is 1 μm or less, the surface of the molded product of the present embodiment tends to be obtained. Mirror surface properties can be obtained by preventing the appearance of fine ripple-like defects, and in the case of heat molding, deterioration of surface gloss can be suppressed in the stretched portion, and transparency can be ensured.

As a method for measuring the average particle size of the rubbery polymer, a conventionally known method can be used, and examples thereof include the methods shown in the following (1) and (2).
(1) After cutting out a part of the molded body of the methacrylic resin composition with a round saw, a sample for observation by the _RuO4 (ruthenium acid) -stained ultrathin section method was prepared, and manufactured by Hitachi, Ltd. The cross section of the stained rubber particles is observed using a transmission electron microscope (model: H-600 type), and then an image is taken. The average particle diameter of the rubber particles is obtained by measuring the diameters of 20 typical particles printed at high magnification on a scale and obtaining the average value of the particle diameters.
(2) The emulsion of the rubbery polymer was sampled, diluted with water so as to have a solid content of 500 ppm, and the absorbance at a wavelength of 550 nm was measured using a UV1200V spectrophotometer (manufactured by Shimadzu Corporation). From this value, the average particle size of a sample whose particle size has been measured from a transmission electron micrograph is obtained using a calibration curve prepared by measuring the absorbance in the same manner.
In both of the above-mentioned measurement methods (1) and (2), substantially the same particle size measurement value can be obtained.

The difference between the refractive index of the methacrylic resin and the refractive index of the rubbery polymer shall be 0.03 or less from the viewpoint of transparency and the temperature dependence of transparency in the molded product of the present embodiment. Is preferable, more preferably 0.025 or less, still more preferably 0.02 or less.

Examples of the method for producing a rubbery polymer include emulsion polymerization.
Specifically, as described above, when the rubbery polymer is composed of three layers, the first layer of the monomer mixture is first added in the presence of the emulsifier and the polymerization initiator to complete the polymerization. Next, by adding the second layer monomer mixture to complete the polymerization, and then adding the third layer monomer mixture to complete the polymerization, the rubbery polymer (particles) can be easily latexed. Can be obtained as.
This rubbery polymer can be recovered as a powder from latex by a known method such as salting out, spray drying, and freeze drying.
When the rubbery polymer is a polymer composed of three layers, it is possible to avoid agglomeration of particles of the rubbery polymer by providing a hard layer in the third layer.

-Other resins-
The methacrylic resin composition of the present embodiment may contain a combination of other resins in addition to the above-mentioned methacrylic resin and rubbery polymer.
As the other resin, a known thermoplastic resin can be used as long as it can exhibit the characteristics required for the methacrylic resin composition of the present embodiment.
The thermoplastic resin is not limited to the following, but is not limited to, for example, polyethylene-based resin, polypropylene-based resin, polystyrene-based resin, syndiotactic polystyrene-based resin, polycarbonate-based resin, ABS resin, acrylic-based resin, AS. Resin, BAAS resin, MBS resin, AAS resin, biodegradable resin, polycarbonate-ABS resin alloy, polyalkylene allylate resin (polybutylene terephthalate, polyethylene terephthalate, polypropylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, etc.) , Polyene-based resin, polyphenylene ether-based resin, polyphenylene sulfide-based resin, phenol-based resin and the like.
In particular, AS resin and BAAS resin are preferable from the viewpoint of improving fluidity, ABS resin and MBS resin are preferable from the viewpoint of improving impact resistance, and polyester resin is preferable from the viewpoint of improving chemical resistance. Further, polyphenylene ether-based resin, polyphenylene sulfide-based resin, phenol-based resin and the like are preferable from the viewpoint of improving flame retardancy. Polycarbonate-based resins are preferable when it is necessary to impart heat resistance, impact resistance, or adjust optical characteristics. Further, the acrylic resin has good compatibility with the above-mentioned methacrylic resin, and is preferable when the properties such as fluidity and impact resistance are adjusted while maintaining the transparency.
As the various thermoplastic resins, only one kind may be used alone, or two or more kinds of resins may be used in combination.

In the methacrylic resin composition of the present embodiment, when the above-mentioned methacrylic resin and the other resin are used in combination, the effect of the present invention may be exhibited as long as the effect of the present invention can be exhibited, but the effect of imparting the characteristic can be obtained. In consideration, the blending ratio of the other resin is 95% by mass or less when the general-purpose acrylic resin is blended as the other resin with respect to the total amount of 100% by mass of the above-mentioned methacrylic resin and the other resin. It is more preferably 85% by mass or less, further preferably 80% by mass or less, still more preferably 75% by mass or less; and when a resin other than the acrylic resin is blended as another resin. The total amount of the above-mentioned methacrylic resin and other resins is preferably 50% by mass or less, more preferably 45% by mass, still more preferably 40% by mass or less, still more. It is preferably 30% by mass or less, and even more preferably 20% by mass or less.
Further, in consideration of the effect of imparting characteristics when blending other resins, the lower limit of the blending amount when blending other resins is preferably 0.1% by mass or more, more preferably 1% by mass or more, and further. It is preferably 2% by mass or more, still more preferably 3% by mass or more, and even more preferably 5% by mass or more.
The type and content of the other resin can be appropriately selected according to the expected effect when used in combination with the other resin.

-Additive-
A predetermined additive may be added to the methacrylic resin composition of the present embodiment in order to impart various properties such as rigidity and dimensional stability.
The additive is not limited to the following, but is, for example, various stabilizers such as an ultraviolet absorber, a heat stabilizer, and a light stabilizer; a plasticizer (paraffin-based process oil, naphthen-based process oil, aromatic-based). Process oil, paraffin, organic polysiloxane, mineral oil); flame retardant (eg, organic phosphorus compound, red phosphorus, phosphorus such as inorganic phosphate, halogen, silica, silicone, etc.); flame retardant aid (For example, antimonides oxide, metal oxides, metal hydroxides, etc.); Hardeners (diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, diethylaminopropylamine, 3,9-bis (3-aminopropyl) ) -2,4,8,10-Tetraoxaspiro [5,5] Undecane, Mensendiamine, Isophoronediamine, N-Aminoethylpiperazin, m-Xylenediamine, m-Fehyrendamine, Diaminophenylmethane, Diaminodiphenyl Aminates such as sulfone, dicyandiamide and adipic acid dihydrazide, phenolic resins such as phenol novolak resin and cresol novolak resin, polymercaptan such as liquid polymercaptan and polysulfide, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, Methyltetrahydrochloride phthalic acid, methylhexahydroanhydride, methylnadic acid anhydride, pyromellitic anhydride, methylcyclohexenetetracarboxylic acid anhydride, succinic anhydride, trimellitic anhydride, chlorendic acid anhydride, benzophenonetetracarboxylic acid Acid anhydrides, acid anhydrides such as ethylene glycol bis (anhydrotrimate), etc.); Hardening accelerators (2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2) -Imidazoles such as undecylimidazole, 2-heptadecylimidazole, 2-phenyl-4-methylimidazole, organic phosphines such as triphenylphosphine and tributylphosphine, benzyldimethylamine, 2-dimethylaminomethyl) phenol, 2, Tertiary amines such as 4,6-tris (diaminomethyl) phenol and tetramethylhexanediamine, boron salts such as triphenylphosfine tetraphenylborate, tetraphenylphosphonium tetraphenylborate, and triethylamine tetraphenylborate, 1,4- Benzo Kinoid compounds such as quinone, 1,4-naphthoquinone, 2,3-dimethyl-1,4-benzoquinone, 2,6-dimethylbenzoquinone, 2,3-dimethoxy-1,4-benzoquinone); antistatic agents (eg, , Polypolymer elastomer, quaternary ammonium salt system, pyridine derivative, aliphatic sulfonate, aromatic sulfonate, aromatic sulfonate copolymer, sulfate ester salt, polyhydric alcohol partial ester, alkyl diethanolamine, alkyl diethanolamide , Polyalkylene glycol derivatives, betaine-based, imidazoline derivatives, etc.); Conductivity-imparting agents; Stress relievers; Mold release agents (alcohols and esters of alcohols and fatty acids, esters of alcohols and dicarboxylic acids, silicone oils, etc.); Crystallization accelerator; Hydrolysis inhibitor; Lubricants (eg, higher fatty acids such as stearate, behenic acid, zinc stearate, calcium stearate, magnesium stearate, and metal salts thereof, higher fatty acids such as ethylene bisstearoamide) (Amids, etc.); Impact-imparting agents; Sliding improvers (hydrogen-based materials such as low-molecular-weight polyethylene, higher alcohols, polyhydric alcohols, polyglycols, polyglycerols, higher fatty acids, higher fatty acid metal salts, fatty acid amides, fatty acids, etc. Esters with aliphatic alcohols, full or partial esters of fatty acids and polyhydric alcohols, full or partial esters of fatty acids and polyglycols, silicones, fluororesins, etc.); compatibilizers; nucleating agents; fillers, etc. Reinforcement agent; Flow conditioner; Dyes (nitroso dye, nitro dye, azo dye, stillben azo dye, ketoimine dye, triphenylmethane dye, xanthene dye, aclysine dye, quinoline dye, methine / polymethine dye, thiazole dye, indamine / Indophenol dyes, azine dyes, oxazine dyes, thiazine dyes, sulfurized dyes, aminoketone / oxyketone dyes, anthraquinone dyes, indigoid dyes, phthalocyanine dyes and other dyes); sensitizers; colorants (titanium oxide, carbon black, titanium yellow, etc.) Inorganic pigments such as iron oxide pigments, ultramarine, cobalt blue, chromium oxide, spinel green, lead chromate pigments, cadmium pigments, azolake pigments, benzimidazolone pigments, dialilide pigments, condensed azo pigments and other azo pigments, Phthalocyanin-based pigments such as phthalicyanin blue and phthalocyanine green, isoindolinone pigments, quinophthalone pigments, kinaku Organic pigments such as lidone pigments, perylene pigments, anthraquinone pigments, perinone pigments, condensed polycyclic pigments such as dioxazine violet, flaky aluminum metallic pigments, spherical pigments used to improve weld appearance. Aluminum pigments, mica powder for pearl-like metallic pigments, and other metallic pigments such as polyhedron particles of inorganic substances such as glass coated with metal plating or sputtering); thickeners; anti-settling agents; anti-sagging agents; fillers (Fibrous reinforcing agents such as glass fibers and carbon fibers, as well as glass beads, calcium carbonate, talc, clay, etc.); Antifoaming agent, etc.); Coupling agent; Light-diffusing fine particles; Anti-rust agent; Antibacterial / antifungal agent; Antifouling agent; Conductive polymer and the like.

－－Light diffusing fine particles －－
The light diffusing fine particles are not limited to the following, but are, for example, inorganic fine particles such as alumina, titanium oxide, calcium carbonate, barium sulfate, silicon dioxide, and glass beads, styrene crosslinked beads, MS crosslinked beads, and siloxane. Examples thereof include organic fine particles such as system-crosslinked beads. Further, hollow crosslinked fine particles made of a highly transparent resin material such as an acrylic resin, a polycarbonate resin, an MS resin, and a cyclic olefin resin, hollow fine particles made of glass, and the like can also be used as light diffusing fine particles.
As the inorganic fine particles, alumina, titanium oxide and the like are more preferable from the viewpoint of diffusibility and availability.
Further, as the light diffusing fine particles, only one kind may be used alone, or two or more kinds may be used in combination.

Here, the refractive index of the light diffusing fine particles is preferably 1.3 to 3.0, more preferably 1.3 to 2.5, and even more preferably 1.3 to 2.0. When the refractive index is 1.3 or more, practically sufficient scattering property is obtained in the molded body of the present embodiment, and when it is 3.0 or less, the molded body of the present embodiment is used for the member near the lamp. When this is done, it is possible to suppress scattering in the vicinity of the lamp and effectively prevent the occurrence of uneven brightness and uneven emission light color tone.
The refractive index is a value at a temperature of 20 ° C. based on the D line (589 nm). As a method for measuring the refractive index of the light-diffusing fine particles, for example, the light-diffusing fine particles are immersed in a liquid whose refractive index can be changed little by little, and the interface of the light-diffusing fine particles is observed while changing the refractive index of the liquid. However, there is a method of measuring the refractive index of the liquid when the interface of the light diffusing fine particles becomes unclear. An Abbe refractometer or the like can be used to measure the refractive index of the liquid.

The average particle size of the light diffusing fine particles is preferably 0.1 to 20 μm, more preferably 0.2 to 15 μm, still more preferably 0.3 to 10 μm, and even more preferably 0.4 to 5 μm. ..
When the average particle size is 20 μm or less, light loss due to backward reflection or the like is suppressed, and the incoming light can be efficiently diffused to the light emitting surface side, which is preferable. Further, when the average particle size is 0.1 μm or more, the emitted light can be diffused, and the desired surface emission luminance and diffusivity can be obtained, which is preferable.

Further, the content of the light diffusing fine particles in the methacrylic resin composition of the present embodiment is 0 with respect to 100 parts by mass of the methacrylic resin from the viewpoint of the expression of the light diffusing effect and the uniformity of surface emission. It is preferably .0001 to 0.03 parts by mass, and more preferably 0.0001 to 0.01 parts by mass.

--Heat stabilizer ---
Examples of the heat stabilizer include, but are not limited to, hindered phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and the like. The methacrylic resin of the present embodiment is suitably used in various applications such as melt extrusion, injection molding, and film molding. The heat history received during processing varies depending on the processing method, but it ranges from several tens of seconds like an extruder to tens of minutes to several hours of heat history such as thick-walled molding and sheet molding. There are various.
When receiving a long heat history, it is necessary to increase the amount of the heat stabilizer added in order to obtain the desired heat stability. From the viewpoint of suppressing the bleed-out of the heat stabilizer and preventing the film from sticking to the roll during film formation, it is preferable to use a plurality of types of heat stabilizers in combination, for example, a phosphorus-based antioxidant and a sulfur-based antioxidant. It is preferable to use at least one selected from the agents in combination with a hindered phenol-based antioxidant.
These antioxidants may be used alone or in combination of two or more.

As the thermal stabilizer, from the viewpoint of further excellent thermal stability in the air, a binary system using a hindered phenol-based antioxidant and a sulfur-based antioxidant, or a hindered phenol-based antioxidant and phosphorus. A binary system using a system-based antioxidant is preferable, and a hindered phenol-based antioxidant, a phosphorus-based antioxidant, and a sulfur-based antioxidant are used, especially from the viewpoint of excellent thermal stability in air for a short period and a long period of time. A ternary system using the above three types is more preferable.

The heat stabilizer is not limited to the following, but is, for example, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], thiodiethylenebis [3-( 3,5-Di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 3,3', 3'', 5 , 5', 5''-Hexa-tert-butyl-a, a', a''-(methitylen-2,4,6-triyl) tri-p-cresol, 4,6-bis (octylthiomethyl) -O-cresol, 4,6-bis (dodecylthiomethyl) -o-cresol, ethylene bis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate], hexamethylene Bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) -1,3 , 5-Triazine-2,4,6 (1H, 3H, 5H) -trione, 1,3,5-tris [(4-tert-butyl-3-hydroxy-2,6-xylin) methyl] -1, 3,5-Triazine-2,4,6 (1H, 3H, 5H) -trione, 2,6-di-tert-butyl-4- (4,6-bis (octylthio) -1,3,5-triazine -2-Ilamine) phenol, 2-[1- (2-hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl, 2-tert-acrylic acid Examples thereof include butyl-4-methyl-6- (2-hydroxy-3-tert-butyl-5-methylbenzyl) phenyl.
In particular, pentaerythritol terakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2- [1- (2-Hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl is preferred.

Further, as the hindered phenol-based antioxidant as the heat stabilizer, a commercially available phenol-based antioxidant may be used, and such a commercially available phenol-based antioxidant is limited to the following. However, for example, Irganox (registered trademark) 1010 (Irganox 1010: pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], manufactured by BASF), Irganox 1076. (Irganox 1076: octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, manufactured by BASF), Irganox 1330 (Irganox 1330: 3,3', 3'', 5,5 ', 5''-Hexa-t-butyl-a, a', a''-(methicylene-2,4,6-triyl) tri-p-cresol, manufactured by BASF), Irganox 3114: 1,3,5-Tris (3,5-di-t-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trion, manufactured by BASF ), Irganox 3125 (Irganox 3125, manufactured by BASF), Adecastab (registered trademark) AO-60 (pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], ADEKA). Made), Adecastab AO-80 (3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionylxyoxy] -1,1-dimethylethyl} -2, 4,8,10-Tetraoxaspiro [5.5] Undecane, manufactured by ADEKA), Sumilyzer (registered trademark) BHT (Sumilizer BHT, manufactured by Sumitomo Chemical), Cyanox (registered trademark) 1790 (Cyanox 1790, manufactured by Cytec), Sumilizer GA-80 (Sumilizer GA-80, manufactured by Sumitomo Chemical Co., Ltd.), Sumilizer GS (Sumilizer GS: 2- [1- (2-hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4,6 -Di-tert-pentylphenyl, manufactured by Sumitomo Chemical Co., Ltd., Sumilizer GM (2-tert-butyl-4-methyl-6- (2-hydroxy-3-tert-butyl-5-methylbenzyl) phenyl acrylate) , Sumitomo Chemical Co., Ltd.), Vitamin E (manufactured by Esai), etc. ..
Among these commercially available hindered phenolic antioxidants, Irganox 1010, Adecastab AO-60, Adecastab AO-80, Irganox 1076, Sumilyzer GS and the like are preferable from the viewpoint of the effect of imparting thermal stability with the resin. ..
These may be used alone or in combination of two or more.

The phosphorus-based antioxidant as the heat stabilizer is not limited to the following, but is not limited to, for example, tris (2,4-di-t-butylphenyl) phosphite and bis (2,4-). Bis (1,1-dimethylethyl) -6-methylphenyl) ethyl ester phosphite, tetrakis (2,4-di-t-butylphenyl) (1,1-biphenyl) -4,4'-diylbisphos Phonite, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,4) -Dicumylphenyl) pentaerythritol-diphosphite, tetrakis (2,4-t-butylphenyl) (1,1-biphenyl) -4,4'-diylbisphosphonite, di-t-butyl-m-cresyl- Phosphonite, 4- [3-[(2,4,8,10-tetra-tert-butyldibenzo [d, f] [1,3,2] dioxaphosphepine) -6-yloxy] propyl] -2 -Methyl-6-tert-butylphenol and the like can be mentioned.
Further, a commercially available phosphorus-based antioxidant may be used as the phosphorus-based antioxidant, and such a commercially available phosphorus-based antioxidant is not limited to the following, but is, for example, Irgafos (registered). Trademarks) 168 (Irgafos 168: Tris (2,4-di-t-butylphenyl) phosphite, manufactured by BASF), Irgafos 12: Tris [2-[[2,4,8,10-tetra-t) -Butyldibenzo [d, f] [1,3,2] dioxaphosfefin-6-yl] oxy] ethyl] amine, manufactured by BASF, Irgafos 38: bis (2,4-bis (1) , 1-dimethylethyl) -6-methylphenyl) ethyl ester phosphite, made by BASF), ADEKA STAB 329K (ADK STAB-329K, made by ADEKA), ADEKA STAB PEP-36 (ADK STAB PEP-36, made by ADEKA), ADEKA STAB PEP-36A (ADK STAB PEP-36A, made by ADEKA), ADEKA STAB PEP-8 (ADK STAB PEP-8, ADEKA), ADEKA STAB HP-10 (ADK STAB HP-10, ADEKA), ADEKA STAB 2112 , ADEKA), ADEKA STAB 1178 (ADKA STAB 1178, ADEKA), ADEKA STAB 1500 (ADK STAB 1500, ADEKA) Sandstab P-EPQ (Clariant), Weston 618 (Weston 618, GE), Weston6 619G, manufactured by GE), Ultranox 626 (manufactured by Ultranox 626, manufactured by GE), Sumilizer GP: 4- [3-[(2,4,8,10-tetra-tert-butyldibenzo [d, f]] [ 1,3,2] dioxaphosphepine) -6-yloxy] propyl] -2-methyl-6-tert-butylphenol, manufactured by Sumitomo Chemical Co., Ltd.), HCA (9,10-dihydro-9-oxa-10-phos) Fafenantren-10-oxide, manufactured by Sanko Co., Ltd.) and the like.
Among these commercially available phosphorus-based antioxidants, Irgafos 168, Adecastab PEP-36, Adecastab PEP-36A, Adecastab HP from the viewpoint of the effect of imparting thermal stability in the resin and the effect of combined use with various antioxidants. -10, Adecastab 1178 are preferable, and Adecastab PEP-36A and Adecastab PEP-36 are particularly preferable.
These phosphorus-based antioxidants may be used alone or in combination of two or more.

The sulfur-based antioxidant as the heat stabilizer is not limited to the following, but is, for example, 2,4-bis (dodecylthiomethyl) -6-methylphenol (Irganox 1726, BASF). , 2,4-Bis (octylthiomethyl) -6-methylphenol (Irganox 1520L, manufactured by BASF), 2,2-bis {[3- (dodecylthio) -1-oxoporopoxy] methyl} propane-1 , 3-Diylbis [3-Dodecylthio] Propionate] (ADEKA STAB AO-412S, manufactured by ADEKA), 2,2-Bis {[3- (Dodecylthio) -1-oxoporopoxy] Methyl} Propane-1,3-Diylbis [3 -Dodecylthio] propionate] (Cheminox PLS, manufactured by Chemipro Kasei Co., Ltd.), di (tridecyl) 3,3'-thiodipropionate (AO-503, manufactured by ADEKA) and the like.
Among these commercially available sulfur antioxidants, Adecastab AO-412S and Cheminox PLS are preferable from the viewpoints of the effect of imparting thermal stability in the resin, the effect of being used in combination with various antioxidants, and the viewpoint of handleability.
These sulfur-based antioxidants may be used alone or in combination of two or more.

The content of the heat stabilizer may be any amount as long as it has the effect of improving the heat stability, and if the content is excessive, problems such as bleeding out during processing may occur. It is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, further preferably 1 part by mass or less, still more preferably 0.8 parts by mass or less, still more preferably, with respect to 100 parts by mass of the based resin. It is preferably 0.01 to 0.8 parts by mass, and particularly preferably 0.01 to 0.5 parts by mass.
Further, from the viewpoint of suppressing the thermal decomposition of the resin, suppressing the deterioration of the color tone of the obtained molded body, suppressing the volatilization of the heat stabilizer, and suppressing the generation of silver streaks during the molding process, the methacrylic resin is described. It contains 0.01 to 2 parts by mass (preferably 0.02 to 1 part by mass) of a hindered phenol-based antioxidant with respect to 100 parts by mass, and contains a phosphorus-based antioxidant and a sulfur-based antioxidant in total. It preferably contains 0.01 to 2 parts by mass (preferably 0.01 to 1 part by mass).

--lubricant--
Examples of the lubricant include, but are not limited to, fatty acid esters, fatty acid amides, fatty acid metal salts, hydrocarbon-based lubricants, alcohol-based lubricants and the like.

The fatty acid ester that can be used as the lubricant is not particularly limited, and conventionally known fatty acid esters can be used.
Examples of the fatty acid ester include fatty acids having 12 to 32 carbon atoms such as lauric acid, palmitic acid, heptadecanoic acid, stearic acid, oleic acid, araquinic acid and behenic acid, and monovalent fatty acids such as palmityl alcohol, stearyl alcohol and behenyl alcohol. Ester compounds with fatty alcohols and polyvalent fatty alcohols such as glycerin, pentaerythritol, dipentaerythritol and sorbitan, and composite esters of fatty acids, polybasic organic acids and monovalent fatty alcohols or polyhydric fatty alcohols. Compounds and the like can be used. Examples of such fatty acid ester-based lubricants include cetyl palmitate, butyl stearate, stearyl stearate, stearyl citrate, glycerin monocaprilate, glycerin monocaplate, glycerin monolaurate, glycerin monopalmitate, and glycerin dipalmi. Tate, glycerin monostearate, glycerin distearate, glycerin tristearate, glycerin monooleate, glycerin dioleate, glycerin trioleate, glycerin monolinoleate, glycerin monobehenate, glycerin mono12-hydroxystearate, glycerin Di12-hydroxystearate, glycerintri 12-hydroxystearate, glycerin diacet monostearate, glycerin quinic acid fatty acid ester, pentaerythritol adipic acid stearic acid ester, montanic acid partially saponified ester, pentaerythritol tetrastearate, dipenta Examples thereof include erythritol hexastearate and sorbitan tristearate.
These fatty acid ester-based lubricants can be used alone or in combination of two or more.
Examples of commercially available products include Riken Vitamin's Rikemar (registered trademark) series, Poem (registered trademark) series, Riquester (registered trademark) series, Riquemaster (registered trademark) series, and Kao's Exel (registered trademark) series. Leodor (registered trademark) series, Exepearl (registered trademark) series, Coconard (registered trademark) series can be mentioned, and more specifically, Rikemar S-100, Rikemar H-100, Poem V-100, Rikemar B-100, Rikemar. Examples thereof include HC-100, Rikemar S-200, Poem B-200, Rikestar EW-200, Rikestar EW-400, Exel S-95, and Leodor MS-50.

The fatty acid amide-based lubricant is not particularly limited, and conventionally known lubricants can be used.
Examples of the fatty acid amide-based lubricant include saturated fatty acid amides such as lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide; Fatty acid amide; substituted amides such as N-stearyl stearyl amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stealic acid amide, N-stearyl erucate amide, N-oleyl palmitate amide; methylol Methylolamides such as stearate amides and methylolbechenic acid amides; methylene bisstearic acid amides, ethylene biscapric acid amides, ethylene bislauric acid amides, ethylene bisstearic acid amides (ethylene bisstearyl amides), ethylene bisisostearic acid amides, ethylene. Bishydroxystearic acid amide, ethylene bisbechenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbechenic acid amide, hexamethylene bishydroxystearic acid amide, N, N'-dystearyl adipic acid amide, N, N'- Saturated fatty acid bisamides such as distearyl sevacinic acid amide; unsaturated fatty acids such as ethylene bisoleic acid amides, hexamethylene bisoleic acid amides, N, N'-diorail adipic acid amides, N, N'-diorail sevacinic acid amides. Bisamides; aromatic bisamides such as m-xylylene bisstearic acid amides and N, N'-distearylisophthalic acid amides can be mentioned.
These fatty acid amide-based lubricants can be used alone or in combination of two or more.
Commercially available products include, for example, Diamid (registered trademark) series (manufactured by Nihon Kasei), Amide series (manufactured by Nihon Kasei), Nikka Amide (registered trademark) series (manufactured by Nihon Kasei), Methylol amide series, and Bisamide. Series, Slipax (registered trademark) series (manufactured by Nihon Kasei), Kao wax series (manufactured by Kao), fatty acid amide series (manufactured by Kao), ethylene bisstearic acid amides (manufactured by Dainichi Chemical Industry Co., Ltd.), etc. Be done.

The fatty acid metal salt refers to a metal salt of a higher fatty acid, for example, lithium stearate, magnesium stearate, calcium stearate, calcium laurate, calcium ricinolate, strontium stearate, barium stearate, barium laurate, barium ricinolate, etc. Zinc stearate, zinc laurate, zinc ricinolate, zinc 2-ethylhexoate, lead stearate, lead dibasic stearate, lead naphthenate, calcium 12-hydroxystearate, lithium 12-hydroxystearate and the like can be mentioned. Among them, calcium stearate, magnesium stearate, and zinc stearate are particularly preferable because the obtained transparent resin composition has excellent processability and extremely excellent transparency.
Examples of commercially available products include SZ series, SC series, SM series, and SA series manufactured by Sakai Chemical Industry Co., Ltd.
When the fatty acid metal salt is used, the blending amount is preferably 0.2% by mass or less from the viewpoint of maintaining transparency.

The above-mentioned lubricant may be used alone or in combination of two or more.

The lubricant used is preferably one having a decomposition start temperature of 200 ° C. or higher. The decomposition start temperature can be measured by the 1% weight loss temperature by TGA.

The content of the lubricant may be any amount as long as the effect as a lubricant can be obtained, and if the content is excessive, problems such as bleed-out occurrence during processing and extrusion failure due to screw slip may occur. Therefore, it is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, still more preferably 1 part by mass or less, still more preferably 0.8 parts by mass or less with respect to 100 parts by mass of the methacrylic resin. It is even more preferably 0.01 to 0.8 parts by mass, and particularly preferably 0.01 to 0.5 parts by mass. When added in an amount in the above range, the decrease in transparency due to the addition of the lubricant is suppressed, the adhesion to the metal roll tends to be suppressed during film formation, and the secondary to the film such as primer coating is suppressed. It is preferable because problems such as peeling are unlikely to occur in a long-term reliability test after processing.

－－UV absorber －－
The ultraviolet absorber is not limited to the following, and is, for example, a benzotriazole-based compound, a benzotriazine-based compound, a benzoate-based compound, a benzophenone-based compound, an oxybenzophenone-based compound, a phenol-based compound, and an oxazole-based compound. Examples thereof include malon acid ester compounds, cyanoacrylate compounds, lactone compounds, salicylic acid ester compounds, and benzoxadinone compounds.

Examples of benzotriazole compounds include 2,2'-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazole-2-yl) phenol], 2- (3). 5-Di-tert-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazole-2-yl) -p-cresol, 2- (2H-benzotriazole-2-yl)- 4,6-bis (1-methyl-1-phenylethyl) phenol, 2-benzotriazole-2-yl-4,6-di-tert-butylphenol, 2- [5-chloro (2H) -benzotriazole-2 -Il] -4-Methyl-6-t-butylphenol, 2- (2H-benzotriazole-2-yl) -4,6-di-t-butylphenol, 2- (2H-benzotriazole-2-yl)- 4- (1,1,3,3-tetramethylbutyl) phenol, 2- (2H-benzotriazole-2-yl) -4-methyl-6- (3,4,5,6-tetrahydrophthalimidylmethyl) ) Phenol, methyl 3- (3- (2H-benzotriazole-2-yl) -5-t-butyl-4-hydroxyphenyl) propionate / reaction product of polyethylene glycol 300, 2- (2H-benzotriazole-2) -Il) -6- (Linear and side chain dodecyl) -4-methylphenol, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α,) α-dimethylbenzyl) phenyl] -2H-benzotriazole, 3- (2H-benzotriazole-2-yl) -5- (1,1-dimethylethyl) -4-hydroxy-C7-9 side chain and linear alkyl Esther can be mentioned.

Examples of benzotriazine compounds include 2-mono (hydroxyphenyl) -1,3,5-triazine compounds, 2,4-bis (hydroxyphenyl) -1,3,5-triazine compounds, and 2,4,6-tris. Examples thereof include (hydroxyphenyl) -1,3,5-triazine compounds, specifically 2,4-diphenyl-6- (2-hydroxy-4-methoxyphenyl) -1,3,5-triazine, 2 , 4-Diphenyl-6- (2-hydroxy-4-ethoxyphenyl) -1,3,5-triazine, 2,4-diphenyl- (2-hydroxy-4-propoxyphenyl) -1,3,5-triazine , 2,4-Diphenyl- (2-hydroxy-4-butoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxyphenyl) -1,3,5 -Triazine, 2,4-diphenyl-6- (2-hydroxy-4-hexyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-octyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-dodecyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy- 4-benzyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxyethoxy) -1,3,5-triazine, 2,4-bis (2-) Hydroxy-4-butoxyphenyl) -6- (2,4-dibutoxyphenyl) -1,3-5-triazine, 2,4,6-tris (2-hydroxy-4-methoxyphenyl) -1,3, 5-Triazine, 2,4,6-Tris (2-hydroxy-4-ethoxyphenyl) -1,3,5-Triazine, 2,4,6-Tris (2-hydroxy-4-propoxyphenyl) -1, 3,5-Triazine, 2,4,6-Tris (2-hydroxy-4-butoxyphenyl) -1,3,5-Triazine, 2,4,6-Tris (2-hydroxy-4-butoxyphenyl)- 1,3,5-Triazine, 2,4,6-Tris (2-hydroxy-4-hexyloxyphenyl) -1,3,5-Triazine, 2,4,6-Tris (2-hydroxy-4-octyl) Oxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-dodecyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2,4,6-tris) 2-Hydroxy-4-benzyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-ethoxyethoxyphenyl) -1,3,5-triazine, 2,4 6-Tris (2-hydroxy-4-butoxyethoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-propoxyethoxyphenyl) -1,3,5-triazine, 2,4,6-Tris (2-hydroxy-4-methoxycarbonylpropyloxyphenyl) -1,3,5-triazine, 2,4,6-Tris (2-hydroxy-4-ethoxycarbonylethyloxyphenyl)- 1,3,5-triazine, 2,4,6-tris (2-hydroxy-4- (1- (2-ethoxyhexyloxy) -1-oxopropan-2-yloxy) phenyl) -1,3,5 -Triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-methoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4) -Ethoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-propoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-Hydroxy-3-methyl-4-butoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-butoxyphenyl) -1,3,5 -Triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-hexyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl- 4-octyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-dodecyloxyphenyl) -1,3,5-triazine, 2,4 6-Tris (2-hydroxy-3-methyl-4-benzyloxyphenyl) -1,3,5-triazine, 2,4,6-Tris (2-hydroxy-3-methyl-4-ethoxyethoxyphenyl)- 1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-butoxyethoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy) -3-Methyl-4-propoxyethoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-methoxycarbonylpropyloxy) Phenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-ethoxycarbonylethyloxyphenyl) -1,3,5-triazine, 2,4,6- Tris (2-hydroxy-3-methyl-4- (1- (2-ethoxyhexyloxy) -1-oxopropan-2-yloxy) phenyl) -1,3,5-triazine and the like can be mentioned.
Among them, 2,4-bis (2,4-dimethylphenyl) -6- [2-hydroxy-4. -(3-Alkyloxy-2-hydroxypropyloxy) -5-α-cumylphenyl] -s-triazine skeleton ("alkyloxy" means long-chain alkyloxy groups such as octyloxy, nonyloxy, and decyloxy). Examples thereof include an ultraviolet absorber having.

As the ultraviolet absorber, benzotriazole-based compounds and benzotriazine-based compounds are particularly preferable from the viewpoint of compatibility with the resin and volatilization during heating, and decomposition of the ultraviolet absorber itself is suppressed by heating during extrusion processing. From the viewpoint, benzotriazine compounds are preferable.

Only one kind of these ultraviolet absorbers may be used alone, or two or more kinds thereof may be used in combination.

Ultraviolet absorbers are usually added to absorb ultraviolet light and suppress transmission of 200 to 380 nm, but it is necessary to add a large amount for thin films and the like, and only one type of ultraviolet absorber is effective. Permeation cannot be suppressed. In order to efficiently suppress transmission with a small amount, it is preferable to use two kinds of a compound having an absorption maximum at a wavelength of 200 to 315 nm and a compound having an absorption maximum at a wavelength of 315 to 380 nm in combination. For example, 2- (4,6-diphenyl-1,3,5-triazine-2-yl) -5- [2- (2-ethylhexanoyloxy) ethoxy] phenol (with an absorption maximum of 280-300 nm). ADEKA Co., Ltd., LA-46) or hydroxyphenyltriazine-based tinubin (registered trademark) 405 (BASF) and 2,4-bis [2-hydroxy-4-] having an absorption maximum of 350 to 380 nm. Butoxyphenyl] -6- (2,4-dibutoxyphenyl) 1,3,5-triazine (BASF, Tinubin 460), hydroxyphenyltriazine-based Tinubin 477 (BASF), and 2,4,6 -It is preferable to use in combination with at least one selected from the group consisting of tris (2-hydroxy-4-hexyloxy-3-methylphenyl) -1,3,5-triazine (manufactured by ADEKA Co., Ltd., LA-F70).

The melting point (Tm) of the ultraviolet absorber is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, further preferably 130 ° C. or higher, and further preferably 160 ° C. or higher. More preferred.
The weight loss rate of the ultraviolet absorber when the temperature is raised from 23 ° C. to 260 ° C. at a rate of 20 ° C./min is preferably 50% or less, more preferably 30% or less, and more preferably 15% or less. Is even more preferably, 10% or less is even more preferable, and 5% or less is even more preferable.

The blending amount of the ultraviolet absorber may be an amount that does not impair heat resistance, moisture heat resistance, thermal stability, and moldability and exhibits the effect of the present invention, but if a large amount is added, it may be added. Since problems such as bleed-out may occur during processing, the amount is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and further preferably 2. It is 5 parts by mass or less, more preferably 2 parts by mass or less, still more preferably 1.8 parts by mass or less, and more preferably 0.01 parts by mass or more.

Hereinafter, the characteristics of the methacrylic resin composition of the present embodiment will be described in detail.

<Contents of foreign matter (number of foreign matter)>
The methacrylic resin composition of the present embodiment is measured with a particle counter from the viewpoint of continuous productivity, from the viewpoint of not causing turbidity of the long light path molded piece, and from the viewpoint of suppressing breakage during film formation of the stretched film. The content of foreign matter having a diameter of 10 μm or more and less than 20 μm needs to be 100 or less per 1 g, preferably 80 or less per 1 g, and more preferably 50 or less per 1 g. Further, when the content of the minute foreign matter is within the above range, the color tone of the molded product, particularly the whiteness, can be improved.
Here, the "foreign substance" refers to carbides such as black and brown that are generated due to thermal deterioration of the resin in the resin composition. In the present specification, a foreign substance having a particle size of 10 μm or more and less than 20 μm as measured by a particle counter is also referred to as a minute foreign substance.
Further, the methacrylic resin composition of the present embodiment has a content of foreign matter having a particle size of 20 μm or more per 1 g as measured by a particle counter from the viewpoint of continuous productivity, physical properties and appearance of the molded body. The number is preferably 100 or less, more preferably 80 or less per 1 g, and further preferably 50 or less per 1 g.
The content of foreign matter in the methacrylic resin composition is measured by a particle counter, and specifically, it can be measured by the method described in Examples described later.

<Glass transition temperature>
The glass transition temperature of the methacrylic resin composition of the present embodiment is 110 ° C. or higher, preferably 115 ° C. or higher, more preferably 117 ° C. or higher, still more preferably 120 ° C. or higher, from the viewpoint of heat resistance during actual use. Particularly preferably, it is 125 ° C. or higher.
The glass transition temperature is preferably high, but the glass transition temperature is 160 ° C. or lower, preferably 155 ° C. or lower, more preferably 150 ° C. from the viewpoint of suppressing the generation of bubbles due to the decomposition of the resin during processing. Below, it is more preferably 145 ° C. or lower, and particularly preferably 140 ° C. or lower.
The glass transition temperature can be measured by the midpoint method according to ASTM-D-3418, and specifically, can be measured by the method described in Examples described later.

<Weight average molecular weight, molecular weight distribution>
The weight average molecular weight (Mw) of the methacrylic resin composition of the present embodiment is 65,000 to 300,000 from the viewpoint of further improving mechanical strength such as Charpy impact strength, solvent resistance and fluidity. Is preferable.
From the viewpoint of maintaining mechanical strength, the weight average molecular weight is preferably 65,000 or more, more preferably 70,000 or more, still more preferably 80,000 or more, still more preferably 100,000 or more. The weight average molecular weight is preferably 250,000 or less, more preferably 230,000 or less, still more preferably 220,000 or less, still more preferably 200,000 or less, and particularly preferably 200,000 or less, from the viewpoint of ensuring fluidity during molding. It is preferably 180,000 or less, and particularly preferably 170,000 or less.
Further, the molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the methacrylic resin composition of the present embodiment is 1.5 to 5 in consideration of the balance between fluidity, mechanical strength and solvent resistance. It is preferably 5. It is more preferably 1.5 to 4.5, still more preferably 1.6 to 4, even more preferably 1.6 to 3, and even more preferably 1.6 to 2.5.
The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the methacrylic resin composition of the present embodiment can be measured by gel permeation chromatography (GPC) in the same manner as in the case of the above methacrylic resin. can. More specifically, it can be measured by the method described in Examples described later.

<Thermal stability>
When a molded product is manufactured using the methacrylic resin composition of the present embodiment, the resin may stay in a molten state in the molding machine. At that time, since the resin material stays at a high temperature for a long time, it is required that the resin material is not easily thermally decomposed, that is, thermal stability is required.
Further, when it is necessary to make the molded body of the present embodiment thin, it is necessary to perform molding at a high temperature, and high thermal stability is required.
As an index of thermal stability, a weight loss rate when the body is held at a predetermined temperature for a predetermined time and a temperature (thermal decomposition start temperature) when the weight is reduced by a predetermined rate can be used.
The methacrylic resin composition of the present embodiment may raise the resin temperature during processing, and in consideration of thermal stability during high-temperature processing, it is measured by thermogravimetric analysis (TGA) in a nitrogen atmosphere, 280. The weight loss rate when heated at ° C. for 1 hour is preferably 5% or less, more preferably 4% or less, still more preferably 3% or less, still more preferably 2% or less, and particularly preferably 1.5% or less. Is. When the weight reduction rate is 5% or less, the heat resistance and thermal stability are further excellent.
Here, the methacrylic resin is generally easily depolymerized by heat, and although the depolymerization by heat can be suppressed by copolymerizing with the acrylic acid ester-based monomer, the heat resistance is lowered. There is. Further, the heat resistance is improved by copolymerizing with a monomer having a ring structure in the main chain, but the mechanical strength may be lowered. In recent years, there has been a demand for a resin having excellent heat resistance and thermal stability.
Further, in the molding and extrusion of a resin composition, the resin is formed when it stays for a long time under high temperature heating or when it is molded by introducing nitrogen to remove oxygen to some extent. It may deteriorate to form a low molecular weight substance, the sheet may stick to the roll when it is formed into a sheet, or the resin may stick to the mold at the time of molding. The methacrylic resin composition of the present embodiment is excellent in thermal stability because the formation of low molecular weight substances is suppressed when the weight loss rate when heated at 280 ° C. for 1 hour in a nitrogen atmosphere is 5% or less. In addition, it suppresses the sticking of the sheet to the roll and suppresses the sticking to the mold, so that it has excellent molding processability.
In this specification, the weight loss rate measured by thermogravimetric analysis can be measured by the method described in Examples described later. The weight loss rate when heated at 280 ° C. for 1 hour can be adjusted, for example, by gradually reducing the amount of the initiator added during polymerization in order to maintain the component content having a molecular weight of 10,000 or less at an appropriate amount. ..
In heat-resistant acrylic resin, it may be necessary to raise the resin temperature during processing, and considering the thermal stability during high-temperature processing, it is measured by thermogravimetric analysis (TGA) at 290 ° C in a nitrogen atmosphere. The weight loss rate when heated for 0.5 hours is 5% or less, preferably 4% or less, and more preferably 3% or less. When the weight reduction rate is 5% or less, heat resistance and thermal stability are excellent.

The methacrylic resin composition of the present embodiment has a weight loss rate of 20% or less, preferably 15% or less, as measured by thermogravimetric analysis, when heated at 280 ° C. for 0.5 hours. It is preferably 10% or less, more preferably 7% or less, and particularly preferably 5% or less. When the weight reduction rate is 20% or less, the thermal stability is excellent.
Here, if a trouble or the like occurs while the molding machine or the extruder is being used and the machine is stopped for a long period of time, the amount of resin supplied into the device may be reduced. In this case, the heated resin comes into contact with air and easily deteriorates. The resin tends to deteriorate in an environment containing oxygen such as in the air, and foreign substances such as black foreign matter and brown foreign matter may be generated due to the decomposition of the resin. The methacrylic resin composition of the present embodiment has a weight loss rate of 20% or less when heated at 280 ° C. for 0.5 hours in air, and the resin is not easily decomposed even in high temperature air, so that black foreign matter or brown foreign matter or brown foreign matter is not easily decomposed. It is possible to suppress the generation of foreign substances such as, and it is possible to obtain a molded product having a good color tone regardless of whether the residence time is long or short.
The weight loss rate when heated at 280 ° C. for 0.5 hours is adjusted by, for example, adjusting the amount of low molecular weight body contained in the resin, that is, the content of components of more than 10,000 to 50,000 or less as an appropriate amount. be able to.

The thermal decomposition start temperature (temperature when the weight is reduced by 1%) (° C.) of the methacrylic resin composition of the present embodiment is preferably 290 ° C. or higher. It is more preferably 300 ° C. or higher, still more preferably 310 ° C. or higher, even more preferably 320 ° C. or higher, and even more preferably 325 ° C. or higher.
The thermal decomposition start temperature may be, for example, a 1% weight loss temperature (thermal decomposition start temperature), which is a temperature at which the weight is reduced by 1% when the temperature is raised. Specifically, the difference used for thermal weight measurement. After holding at a predetermined temperature for a predetermined time (for example, 100 ° C. for 5 minutes) using a heat balance or the like, the temperature is raised to a predetermined temperature (for example, 400 ° C. at 10 ° C./min) at a predetermined temperature rise rate. However, the point at which the 1% weight is reduced can be set as the thermal decomposition start temperature (1% weight loss temperature).

The methacrylic resin composition of the present embodiment has a YI value of a test piece having a thickness of 2 mm, a width of 100 mm, and a length of 100 mm, which is produced by an injection molding machine under the conditions of a molding temperature of 280 ° C. and a mold temperature of 60 ° C. , It is preferably 10 or less, more preferably 8 or less, still more preferably 5 or less, regardless of the injection molding cycle time (injection time + cooling time).
Further, the difference (degree of change in YI value) between the YI value of (a) 45 seconds and the YI value of (b) 270 seconds of the injection molding cycle time is preferably 2.5 or less, more preferably. It is 2 or less, more preferably 1.5 or less, and particularly preferably 1 or less.
The YI value can be measured according to JIS K 7105 using, for example, a colorimeter (manufactured by Tokyo Denshoku Co., Ltd., TC-8600A, light source: 10-C). The degree of change in the YI value was determined by measuring the YI value for each of the plurality of test pieces obtained in the cycle times (a) and (b) using the test pieces after the molding became stable, and the cycle time (a). The average value of the YI values of the test pieces of (b) and the average value of the YI values of the test pieces of the cycle time (b) are obtained, and YI is used as the average value of the YI values of (b)-(a). The degree of change in the value can be calculated.

The methacrylic resin composition of the present embodiment is prepared by filling a melt indexer specified in JIS K 7210 with the methacrylic resin composition, holding the methacrylic resin composition in a cylinder at 270 ° C. for 10 minutes, and then holding the piston under a load of 2.16 kg. The methacrylic resin composition is extruded into a strand shape from the upper marked line to the lower marked line, and the number of bubbles having a major axis of 2 to 50 μm present in the strand extruded between the upper marked line and the lower marked line is the thermal stability. From the viewpoint of appearance after molding and molding processability, the number is preferably 20 or less per gram, more preferably 15 or less, still more preferably 10 or less, still more preferably 8 or less, and particularly preferably. Is 5 or less.
Here, the resin containing the methacrylic acid ester monomer unit may be depolymerized by heat and decomposed into monomer components. In order to improve heat resistance, when a copolymer containing other monomer units in addition to the methacrylic ester monomer unit is used, the melting temperature becomes higher and the processing temperature becomes higher, and further during processing. The melt viscosity of the resin will increase.
For example, in order to remove foreign substances in the methacrylic resin, a polymer filter may be introduced into the extruder during processing. However, the use of polymer filters exposes the resin to high temperatures for a relatively long period of time. When heat of about 250 to 300 ° C. is received for a long period of time, fine bubbles are likely to be generated due to decomposition of the resin or the like. Microbubbles having a fine bubble volume tend to stay in the resin for a long period of time as compared with large bubbles. Large bubbles exceeding 50 μm may be released to the outside of the resin when exiting from the extruder die or the nozzle of the molding machine, but the fine bubbles remain and tend to become bright spot foreign substances in the molded body. Further, when forming a thin film sheet, there is an influence that it is easily broken at the time of film formation, and in order to improve the stability of the manufacturing process, it is preferable that the number of microbubbles is a certain amount or less.
According to the methacrylic resin of the present embodiment, the number of bubbles having a major axis of 2 to 50 μm present in the strands extruded under the above conditions can be 20 or less per 1 g, so that there are few fine bubbles and bright spots in the molded product. Foreign matter is less likely to occur.
In the present specification, the microbubbles may have a size within a range that can be observed with a microscope or the like, but the microbubbles in the present embodiment refer to bubbles having a major axis of 2 μm or more.

The methacrylic resin composition of the present embodiment has, for example, the number of bubbles having a major axis of 100 μm or more contained in 100 cm ² of a film when a film formed by an extruder having a set temperature of 290 ° C. is formed to a thickness of about 100 μm. However, the number is preferably less than 5, more preferably less than 3, still more preferably less than 2, still more preferably less than 1, and particularly preferably 0.8 or less. When the number of bubbles in the film is within the above range, a molded product having excellent appearance can be obtained.
A resin containing a methacrylic acid ester as a main component is easily depolymerized by heat to form a monomer component. If a monomer unit having a group having a ring structure is introduced in order to impart heat resistance to the resin, the processing temperature will increase and the melt viscosity of the resin during processing will increase. According to the methacrylic resin composition of the present embodiment, since the number of bubbles in the film produced under the above conditions is in the above range, it is possible to obtain a molded product having few bubbles and excellent appearance.
The number of bubbles in the film can be evaluated by calculating the number of bubbles using an optical microscope and using the number of bubbles. Specifically, it can be measured by the method described in Examples described later.

In the molding process of the molded body of the present embodiment, in order to prevent thermal decomposition and to have excellent thermal stability in practical use, the methacrylic resin contained in the molded body of the present embodiment has a main chain. It is effective to increase the proportion of the structural unit (B) having a ring structure and relatively decrease the amount of the methacrylic acid ester-based monomer unit (A) to be copolymerized. However, if the ratio of the (B) structural unit to the (A) monomer unit is too high, the characteristics such as molding fluidity and surface hardness required for the molded product may not be obtained. Therefore, it is necessary to determine the ratio of (A) monomer unit and (B) structural unit in consideration of the balance of these characteristics.
Further, increasing the copolymerization ratio of the structural unit (B) having a ring structure in the main chain is effective in suppressing the decomposition reaction due to depolymerization when exposed to a high temperature, and (B) the structural unit. By increasing the ratio of (A) to the monomer unit, sufficient thermal stability can be imparted even if the amount of the thermal stabilizer is reduced. On the other hand, when the proportion of the methacrylic acid ester-based monomer unit (A) is relatively large, the amount of thermal decomposition in a high temperature environment increases. Here, a heat stabilizer may be added from the viewpoint of suppressing thermal decomposition, but if it is added in a large amount, the heat resistance may be lowered and problems such as bleed-out may occur during molding.

Then, as described above, a heat stabilizer may be included in the methacrylic resin composition in order to obtain the properties required for the molded product.

At this time, in the present embodiment, the content of the heat stabilizer is Y (content with respect to 100 parts by mass of methacrylic resin (parts by mass)), the content of the methacrylic acid ester-based monomer unit (A) is P, and the main content is When the content of the structural unit (B) having a ring structure in the chain is Q (both refer to the content (% by mass) with respect to 100% by mass of the methacrylic resin), thermal decomposition suppression at high temperature, From the viewpoint of the balance between moldability and heat resistance, the content Y (part by mass) is preferably 0.053 × P / Q −0.4 or more, and more preferably 0.053 × P / Q. -0.35 or more, still more preferably 0.053 x P / Q-0.3 or more, still more preferably 0.053 x P / Q-0.27 or more, still more preferable. Is 0.053 × P / Q-0.25 or more.

<Continuous productivity>
The methacrylic resin composition of the present embodiment is excellent in production stability in long-term operation, that is, continuous productivity. As the index of continuous productivity, the above-mentioned foreign matter content and extrusion stability can be used. Extrusion stability can be evaluated, for example, by the rate of increase in resin pressure, the particle size distribution of the manufactured pellets, and the like.

In the method for producing a methacrylic resin composition of the present embodiment, a filter such as a polymer filter can be suitably used for an extruder or the like, as will be described later, from the viewpoint of reducing the content of foreign substances. In the manufacturing method using a polymer filter, if the rate of increase in resin pressure in the extruder during long-term operation is large, the foreign matter once trapped in the polymer filter breaks into minute foreign matter and slips through the polymer filter. As a result, for the purpose of removing minute foreign matter, it becomes necessary to reduce the filter diameter to reduce the discharge amount of the extruder and to increase the filter replacement frequency, resulting in a decrease in continuous productivity. When the rate of increase in the resin pressure is small, it is possible to prevent the generation of minute foreign substances and the slip-through of the polymer filter, and it is possible to improve the continuous productivity. Further, when the rate of increase in the resin pressure is small, the pressure at the time of extrusion and the discharge amount are kept substantially constant, and the extrusion stability is excellent.
The rate of increase in the resin pressure varies depending on the interval at which the resin pressure is measured. For example, from the viewpoint of continuous productivity, the rate of increase in resin pressure is 10 when the resin pressure (P ₀ ) 1 hour after the start of extrusion is used as the reference and the resin pressure after 48 hours is (P). % Or less, more preferably 8% or less, and particularly preferably 5% or less. The rate of increase in the resin pressure can be calculated from the following formula.
Resin pressure increase rate (%) = (PP ₀ ) / P ₀ × 100
Specifically, it can be measured by the method described in Examples described later.
By using a pleated filter among the polymer filters, the rate of increase in resin pressure can be further reduced.

Extrusion stability and thus continuous productivity can also be evaluated by the pellet particle size distribution. The narrow particle size distribution of the manufactured pellets, that is, the high uniformity of the pellet size means that the pressure and the discharge amount at the time of extrusion are kept constant, and it can be seen that the extrusion stability is excellent. .. When the extrusion stability is excellent, the frequency of adjusting the extrusion conditions over time can be reduced, and the continuous productivity is excellent.
Regarding the pellet particle size distribution, from the viewpoint of extrusion stability, for example, the proportion of pellets that do not pass through a sieve having a mesh size of 2.36 mm (8 mesh) is preferably 97% by mass or more, preferably 98% by mass or more. More preferably, it is more preferably 99% by mass or more.
Further, from the viewpoint of handleability when processing the obtained pellets into a molded body and suppression of defects such as silver streaks, discoloration, and bubbles during molding, the pellet particle size distribution is narrower, that is, the pellet size is uniform. Higher sex is preferred. For example, it is preferable that the amount of pellets having a size that passes through a sieve having a mesh size of 3.35 mm (6 mesh) and does not pass through a sieve having a mesh size of 2.36 mm (8 mesh) is 75% by mass or more, preferably 85. It is by mass or more, more preferably 90% by mass or more, still more preferably 94% by mass or more, still more preferably 97% by mass or more, and particularly preferably more than 97% by mass.
Here, the pellet particle size distribution (also referred to as "pellet particle size distribution") is evaluated, for example, by calculating the pellet weight ratio remaining on the sieve when sieving according to JIS Z 8801. Can be done. Specifically, it can be measured by the method described in Examples described later.

<Color tone>
The methacrylic resin composition of the present embodiment has a high whiteness because the content of foreign substances is small. Here, the whiteness refers to the hunter whiteness (W) defined by JIS-P8123, and can be calculated by the following formula.
W = 100-√ [(100-L) ² + (a ² + b ² )]
In applications such as a light guide, it is necessary that the whiteness is maintained high even in a long optical path, and the whiteness (W) when viewed in a 220 mm long optical path is preferably 40 or more. It is more preferably 50 or more, still more preferably 60 or more.

(Manufacturing method of methacrylic resin composition)
In the methacrylic resin composition of the present embodiment, the above-mentioned methacrylic resin, a rubbery polymer optionally added, other resins other than the methacrylic resin, and additives are melt-kneaded and extruded. It can be prepared by. Hereinafter, a more specific description will be given.

((Melting and kneading process))
Examples of the method for producing the methacrylic resin composition of the present embodiment include a method of kneading using a kneader such as an extruder, a heating roll, a kneader, a roller mixer, and a Banbury mixer. It can be produced by melt-kneading and extrusion using the conditions shown below as appropriate. Of these, melt-kneading and extrusion using an extruder are preferable in terms of productivity.

-Extruder-
In the production of the methacrylic resin composition of the present embodiment, for example, a general extruder such as a single-screw extruder, a simultaneous twin-screw extruder, a different-direction twin-screw extruder, or a multi-screw extruder can be used. .. A particularly preferable extruder is a device having a large kneading effect, such as a twin-screw kneading extruder.
As an example of the screw configuration of the extruder, a transport section for transporting the raw material and the kneaded material of the resin composition, and a screw segment in which the kneading zone and the molten resin are fed in the opposite directions (screw segments in which the spiral winding direction is opposite). For example, those having a kneading portion for kneading the raw materials of the resin composition. Further, a transport section for transporting the kneaded product of the resin composition to a die section or the like may be further provided behind the kneading section.
The kneading temperature may be in accordance with the preferable processing temperature of the polymer constituting the methacrylic resin and other resins to be mixed, and is in the range of 140 to 300 ° C., preferably 180 to 280 ° C. as a guide.
Further, it is preferable that the extruder is provided with a feeder for controlling the supply amount of the raw material and a vent port for removing volatile components that may be generated during melt-kneading.
The feeder used is suitable for both heavy weight type and capacitive type. From the viewpoint of stabilizing the supply amount, a heavy-duty feeder can be particularly preferably used.

－－L / D－－
The L / D of the extruder is preferably 10 or more, more preferably 15 or more, still more preferably 20 or more, from the viewpoint of sufficiently plasticizing the thermoplastic resin to obtain a good kneaded state. Further, the L / D of the extruder is preferably 100 or less, more preferably 80 or less, still more preferably 60, from the viewpoint of suppressing thermal decomposition of the polymer in the resin composition due to excessive shearing. It is as follows.
Here, L means the effective length of the barrel, and D means the inner diameter of the barrel.

－－Cylinder temperature of raw material transfer part －－
It is desirable that the cylinder temperature of the raw material transfer section of the extruder is set lower than the cylinder temperature of the kneading section.
Here, the "raw material transport section" refers to a portion on the raw material supply side of the kneading section where the raw material of the resin composition is kneaded, and the cylinder temperature of the raw material transport section is an average value of the cylinder set temperature of the raw material transport section. Point to.
Among the raw material transport parts, the cylinder temperature closest to the raw material supply hopper (hereinafter also referred to as "hopper horizontal cylinder temperature") is continuous by suppressing the increase in resin pressure from the viewpoint of suppressing hopper clogging due to resin fusion. From the viewpoint of improving productivity, it is preferable to set the temperature lower than the cylinder temperature of other transport units. Specifically, the temperature of the nearest cylinder of the raw material supply hopper is preferably 5 ° C. or higher, more preferably 10 ° C. or higher, lower than the cylinder temperature of the raw material transport section.

－－Cylinder temperature of kneading part －－
The cylinder temperature of the kneaded portion of the extruder is set within the range of (glass transition temperature of resin composition + 100 ° C.) or more (glass transition temperature of resin composition + 160 ° C.) or less from the viewpoint of melt extrudability and productivity. It is more preferable that the temperature is in the range of (glass transition temperature of the resin composition + 100 ° C.) or more (glass transition temperature of the resin composition + 150 ° C.), more preferably (glass transition temperature of the resin composition + 110 ° C.). It is within the above range (glass transition temperature of resin composition + 140 ° C.) or less. The specific preferred temperature range is 210 ° C to 280 ° C, preferably 220 ° C to 280 ° C, and particularly preferably 230 ° C to 280 ° C. When the cylinder temperature of the kneading portion is within the above temperature range, a resin composition having a better appearance can be obtained.
Here, the "kneading portion" refers to a portion where the resin composition is sheared, such as a kneading zone or a portion having a screw segment in which the feed direction of the molten resin is opposite (screw segment in which the winding direction of the spiral is opposite). .. The cylinder temperature of the kneading portion means the average set temperature of the cylinder temperature of the kneading portion.
From the viewpoint of the appearance of the obtained molded product and the viewpoint of suppressing the increase in resin pressure to improve the continuous productivity, it is preferable to set the cylinder temperature of the kneaded portion higher than the cylinder temperature of the raw material transport portion. .. Specifically, the cylinder temperature of the kneading section is preferably 5 ° C. or higher, more preferably 10 ° C. or higher, higher than the cylinder temperature of the raw material transport section. The upper limit of the difference between the cylinder temperature of the kneading section and the cylinder temperature of the raw material transport section is not particularly limited as long as the pressure of the methacrylic resin composition is not excessively high or low, and is 40 ° C. or lower. It is preferably 30 ° C. or lower, more preferably 30 ° C. or lower.

--Cylinder temperature of the kneaded material carrier ---
The cylinder temperature of the kneaded material transport section can be appropriately set and is not particularly limited. For example, it may be the same temperature as the cylinder temperature of the kneading portion, or it may be the same temperature as the resin temperature of the die head portion described later.
Here, the "kneaded material transport section" refers to a portion that transports the resin composition kneaded in the kneaded section from the kneaded section to the die head section, and the cylinder temperature of the kneaded material transport section is the cylinder of the kneaded material transport section. It means the average set temperature of the temperature.

--Screw rotation speed (Ns) ---
The screw rotation speed (Ns) of the extruder is preferably 50 rpm or more and 800 rpm or less from the viewpoint of suppressing the residence time in the extruder. When a twin-screw extruder is used, the screw rotation speed (Ns) is more preferably 100 rpm or more and 600 rpm or less, more preferably 150 rpm or more and 600 rpm or less, and particularly preferably 200 rpm or more and 600 rpm or less, from the viewpoint of kneading property. be.

((Extrusion process))
The methacrylic resin composition of the present embodiment can be obtained by appropriately extruding the methacrylic resin composition prepared by melt-kneading as described above using the extrusion conditions exemplified below.

－－Discharge amount (Q) －－
The optimum amount of the discharge amount (Q) of the extruder varies depending on the size of the extruder, but it is preferably 10 kg / hr or more and 1000 kg / hr or less from the viewpoint of suppressing the residence time in the extruder and productivity. When a twin-screw extruder is used, the discharge rate (Q) is more preferably 10 kg / hr or more and 1000 kg / hr or less, more preferably 50 kg, from the viewpoints of kneadability, suppression of residence time in the extruder, and productivity. It is more preferably / hr or more and 900 kg / hr or less, and particularly preferably 100 kg / hr or more and 900 kg / hr or less, and 180 kg / hr or more and 800 kg / hr.

－－Discharge amount (Q) / Screw rotation speed (Ns) －－
The ratio (Q / Ns) of the discharge amount (Q) of the extruder to the screw rotation speed (Ns) is sufficiently filled with the resin in the melt extruder from the viewpoint of color tone and thermal stability without starvation. It is desirable to set it within the appropriate range. Specifically, it is preferably 0.1 to 50 kg / (hr · rpm). When a twin-screw extruder is used, the Q / Ns is more preferably 0.1 to 5 kg / (hr · rpm), further preferably 0.2 to 2 kg / (hr · rpm). , 0.4 to 1.5 kg / (hr · rpm) is particularly preferable.

-Resin pressure-
The methacrylic resin composition containing the heat resistant unit tends to generate so-called burnt foreign matter (carbide) more easily than the methacrylic resin composition having no heat resistant unit. The carbide can be removed by passing through a filter after melt-kneading.
The inside of the extruder is held at a certain pressure from the viewpoint of extrusion stability. However, when the resin composition is continuously produced and operated at a high resin pressure for a long period of time, the carbides captured by the filter may be crushed by the pressure to become fine foreign substances and be contained in the resin composition. Therefore, from the viewpoint of suppressing the content of fine foreign substances, it is preferable to set the resin pressure within a certain range.
The resin pressure is preferably kept at 12 MPa or less, more preferably 11 MPa or less, still more preferably 10 MPa or less, from the viewpoint of preventing the discolored resin once collected in the filter from being crushed and passing through the filter during long-term operation. be. When pellets are obtained via an extruder, the resin pressure is preferably 2 MPa or more, more preferably, from the viewpoint of pellet size stability, and when film is formed on a sheet or film, from the viewpoint of thickness accuracy. Is 5 MPa or more, more preferably 6 MPa or more.

-Polymer filter-
A polymer filter can be used as the filter used to remove foreign matter during extrusion. Examples of the polymer filter that can be used include a depth filter, a pleated filter, a candle filter, and a back filter. From the viewpoint of suppressing the content of fine foreign matter, it is preferable to select the optimum filter to be used. Among them, the pleated filter can suppress the increase rate of the resin pressure, suppress the foreign matter captured by the filter from being crushed by the high resin pressure into fine foreign matter, and can also suppress the decrease in the molecular weight due to the decomposition of the resin. ,preferable.
Hereinafter, a pleated filter preferably used will be described in detail.

The filter element of the pleated filter is a filter medium processed into a pleated shape, which is wound around the outer circumference of a support material (retainer) which is cylindrical and has a plurality of holes to form a cylindrical shape. It has a structure with an opening at the end.
The filter is used in the form of a unit in which the filter element is housed (in some cases, a plurality) in a predetermined housing. The closed portion of the filter element is arranged on the upstream side in the housing. The molten resin that has flowed into the filter unit is filled in the gap between the housing and the surface of the filter medium, then passes through the surface of the filter medium, flows into the inside of the cylindrical support, and flows out of the filter unit from the open end of the filter element. ..
This pleated cylindrical filter element can increase the dust collection area per volume as compared with the conventional cylindrical filter element. As a result, it is possible to keep the pressure loss low while maintaining the required dust collection capacity, and the productivity is not impaired. In addition, since the volume occupied by the filter element can be reduced, not only the effect of reducing minute foreign matters but also the size of the filter device itself can be reduced, and the manufacturing cost, installation cost, operating cost, etc. can be reduced. can.

The material of the filter medium of the pleated filter is not particularly limited, and those generally used as the material of the filter medium of the polymer filter can be used. For example, a material made of sintered metal fiber non-woven fabric, a material made of sintered metal powder, a material made of wire mesh, and the like can be mentioned, and among them, a material made of sintered metal fiber non-woven fabric is preferable.

The filtration accuracy of the pleated filter is preferably in the range of 1 μm or more and 25 μm or less, more preferably 3 μm or more and 20 μm or less, and further preferably 5 μm or more and 15 μm or less. From the viewpoint of reducing foreign matter, the filtration accuracy is preferably 25 μm or less. Further, by setting the filtration accuracy to 1 μm or more, the residence time in the filter can be shortened, and it is possible to prevent the resin composition from being thermally deteriorated and increasing foreign substances.
Further, if the flow rate of the resin composition is increased for the purpose of shortening the residence time in the filter in order to prevent thermal deterioration of the resin composition, the resin pressure at the inlet of the filter increases and foreign substances larger than the filtration accuracy are crushed. It becomes easier to pass through the filter medium. In order to prevent this, it is preferable to control the flow rate in the above pressure range.

By using a filter unit in which a plurality of filter elements are housed in one housing as a pleated filter, the filtration area can be increased and the pressure loss can be reduced. The number of elements is preferably 3 to 7, more preferably 3 to 4.
The length of the filter element can be appropriately selected depending on the amount of resin processed per hour, but is preferably in the range of 300 to 1200 mm, more preferably 300 to 600 mm, and further preferably 400 to 600 mm. When the element length is 300 mm or more, the filtration area is not too small and the amount of resin processed per hour is not too small, so that productivity can be improved and the content of foreign substances can be reduced. When the element length is 1200 mm or less, the residence time in the filter is not too long, so that it is possible to prevent the resin composition from being thermally deteriorated and increasing foreign substances.

-dice-
The number of holes in the die of the extruder is not particularly limited, and can be appropriately selected in consideration of the hole diameter of the die, the discharge amount (Q) of the resin composition, and other conditions.
From the viewpoint of extrusion stability and the viewpoint of making the obtained pellet sizes uniform, the discharge amount (discharge amount / number of holes) of the methacrylic resin composition per hour per hole of the die at the time of extrusion is 5 kg. It is preferably / (hr / piece) or more and 30 kg / (hr / piece) or less. More preferably 6.5 kg / (hr · piece) or more, further preferably 8 kg / (hr · piece) or more, particularly preferably 10 kg / (hr · piece) or more, particularly preferably over 10 kg / (hr · piece). be.
Further, from the viewpoint of suppressing vent-up and resin pressure during extrusion, the discharge amount / number of holes is more preferably 25 kg / (hr · piece) or less, still more preferably 20 kg / (hr · piece) or less, and particularly preferably. It is 18 kg / (hr / piece) or less.
The hole diameter of the die may be appropriately selected to have a size necessary for obtaining a desired pellet size, and can be appropriately selected in the range of usually φ2.5 mm to φ6.5 mm. From the viewpoint of handleability when granulating pellets, it is preferably φ2.5 mm to φ6 mm, more preferably φ2.5 mm to φ5 mm, and particularly preferably φ3 mm to φ5 mm.
As described above, by setting the discharge amount / number of holes within a predetermined range and appropriately selecting the hole diameter of the die, a methacrylic resin composition having a low foreign matter content and excellent physical properties and appearance can be produced in an excellent continuous manner. Can be manufactured by sex.

-Dice temperature-
The die temperature of the extruder can be appropriately set and is not particularly limited. For example, it may be set to the same temperature as the cylinder temperature of the kneaded material transport section, or may be set to the same temperature as the resin temperature of the die head section described later.
Here, the "dice temperature" means the average set temperature of the dice.

-Temperature of methacrylic resin composition in the die head part-
The temperature of the methacrylic resin composition at the die head portion of the extruder (hereinafter, also referred to as resin temperature) is preferably [glass transition temperature (Tg) + 100 ° C. of the methacrylic resin] or higher, and more preferably Tg + 110 ° C. Above, more preferably Tg + 120 ° C. or higher, and particularly preferably Tg + 130 ° C. or higher. At the above resin temperature, the dispersibility of the methacrylic resin composition becomes good, and when molded into a molded product, the surface condition becomes good and the appearance becomes good. In particular, when producing a film-shaped molded product, die lines are reduced and a film having a good appearance can be obtained. The specific resin temperature is, for example, 250 ° C. or higher, more preferably 260 ° C. or higher, and particularly preferably 270 ° C. or higher. Further, from the viewpoint of suppressing the decomposition of the resin, it is preferable to appropriately set the conditions so that the resin temperature is 310 ° C. or lower.

(pellet)
The pellet of the present embodiment is characterized by containing the above-mentioned methacrylic resin composition of the present embodiment.

The pellets of the present embodiment can be suitably used as a molded body to be described later used as an optical component such as an optical film, or as a raw material for injection molding applications such as an in-vehicle component, a lens, and a light guide rod.

(Pellet manufacturing method)
The pellets of the present embodiment can be produced by extruding the methacrylic resin composition through a die having a plurality of holes equipped in an extruder and granulating it in the extrusion process for producing the methacrylic resin composition. can.

For the manufactured pellets, the pellet particle size distribution can be evaluated as described above. Specifically, the pellet particle size distribution can be evaluated by the method described in Examples described later.

(Molded body)
The molded product of the present embodiment is characterized by containing the above-mentioned methacrylic resin composition of the present embodiment.

The molded product of this embodiment is preferably used as an optical component such as an optical film. The molded product of the present embodiment is preferably a film.

The thickness of the molded product of the present embodiment is 0.01 to 1 mm from the viewpoint of excellent handleability and strength, and from the viewpoint of excellent optical characteristics when the molded product of the present embodiment is used as an optical component. preferable.
When the molded product of the present embodiment is used as a film, it may be in the range of 5 to 200 μm. If the thickness is 5 μm or more, sufficient strength can be secured for practical use, and it is difficult to break easily during handling. Further, when the thickness is 200 μm or less, a good balance is obtained in the phase difference (Re, Rth) and the folding resistance described later.
When used as a polarizing element protective film, the thickness of the molded product of the present embodiment may be 5 to 100 μm, 10 to 80 μm, or 10 to 60 μm.
When used as a transparent plastic substrate, the thickness of the molded product of the present embodiment may be 20 to 180 μm, 20 to 160 μm, or 30 to 160 μm.

Hereinafter, the characteristics of the molded product of this embodiment will be described.

<In-plane phase difference Re>
In the molded product of the present embodiment, the absolute value of the in-plane direction difference Re is preferably 30 nm or less. However, here, the in-plane direction phase difference Re is a value obtained by converting to a thickness of 100 μm.
The absolute value of the in-plane direction phase difference Re is more preferably 20 nm or less, further preferably 15 nm or less, and particularly preferably 11 nm or less.
In general, the absolute value of the in-plane directional phase difference Re is an index indicating the magnitude of birefringence. The molded body according to the present embodiment is sufficiently small with respect to the birefringence of existing resins (for example, PMMA, PC, triacetyl cellulose resin, cyclic olefin resin, etc.), and requires low birefringence or zero birefringence as an optical material. It is suitable for applications such as optical components (for example, optical films).
On the other hand, when the absolute value of the in-plane direction difference Re exceeds 30 nm, it means that the refractive index anisotropy is high, and it cannot be used for applications requiring low birefringence or zero birefringence as optical components. be. In addition, stretching may be performed to improve the mechanical strength of optical components (for example, films, sheets, etc.), but if the absolute value of the in-plane directional phase difference Re after stretching exceeds 30 nm, It does not mean that a low birefringence or zero birefringence material has been obtained.

<Thickness direction phase difference Rth>
In the molded product of the present embodiment, the absolute value of the phase difference Rth in the thickness direction is preferably 30 nm or less. However, here, the phase difference Rth in the thickness direction is a value obtained by converting to a thickness of 100 μm.
The absolute value of the thickness direction retardation Rth is more preferably 20 nm or less, further preferably 15 nm or less, and particularly preferably 11 nm or less.
This thickness direction phase difference Rth is an index that correlates with the viewing angle characteristics of the display device incorporating the optical film when it is used as an optical component, particularly an optical film. Specifically, the smaller the absolute value of the thickness direction phase difference Rth, the better the viewing angle characteristic, and the smaller the change in color tone of the display color and the smaller decrease in contrast depending on the viewing angle.
The molded product according to the present embodiment has a feature that the absolute value of the phase difference Rth in the thickness direction is very small as compared with existing resins (for example, PMMA, PC, triacetyl cellulose resin, cyclic olefin resin, etc.).

<Photoelastic coefficient>
In the molded product of the present embodiment, the absolute value of the photoelastic coefficient _CR is preferably 3.0 × ^10-12 Pa ^-1 or less, and preferably 2.0 × ^10-12 Pa ^-1 or less. More preferably, it is 1.0 × 10 ^-12 Pa ^-1 or less.
Photoelastic coefficients are described in various documents (see, for example, Review Articles of Chemistry, No. 39, 1998 (published by the Society Publishing Center)) and are defined by the following formulas (ia) and (ib). Is. It can be seen that the closer the value of the photoelasticity coefficient _CR is to zero, the smaller the birefringence change due to the external force.
_CR = | Δn | / σ _R ... (i-a)
| Δn | = nx-ny ... (i-b)
(In the equation, _{CR is the photoelastic coefficient, σ R is} the elongation stress, | Δn | is the absolute value of birefringence, nx is the refractive index in the extension direction, and ny is perpendicular to the extension direction in the plane. The refractive index in each direction is shown.)
The photoelastic coefficient _CR of the molded product of the present embodiment is sufficiently smaller than that of existing resins (for example, PMMA, PC, triacetyl cellulose resin, cyclic olefin resin, etc.). Therefore, since the (photoelastic) birefringence caused by the external force is not generated, the birefringence change is less likely to occur. Further, since birefringence (photoelasticity) due to residual stress during molding is unlikely to occur, the birefringence distribution in the molding body is also small.

Hereinafter, the relationship between the birefringence Δn and the draw ratio S will be described.
When the characteristics of the molded product of the present embodiment are evaluated as a uniaxially stretched film, the value of the inclination K is as follows in the least squares approximate linear relational expression (ii-a) between the birefringence Δn (S) and the stretching ratio S. It is preferable to satisfy the formula (ii-b).
Δn (S) = K × S + C ... (ii-a)
| K | ≤ 0.30 x ^10-5 ... (ii-b)
(In the formula, Δn (S) indicates birefringence, S indicates the stretching ratio, and here, the birefringence Δn (S) is a value measured as a film (value obtained by the above formula (i-b)). Is a value obtained by converting to 100 μm thickness, C is a constant, and indicates birefringence when unstretched.)
The absolute value (| K |) of the slope K is more preferably 0.15 × ^10-5 or less, and further preferably 0.10 × ^10-5 or less.
Here, the value of K is a value when the glass transition temperature (Tg) is measured by DSC measurement of the film and uniaxial stretching is performed at a stretching temperature of (Tg + 20) ° C. and a stretching speed of 500 mm / min. ..
It is generally known that the amount of increase in birefringence decreases as the stretching speed is reduced. As the value of K, for example, the value of birefringence (Δn (S)) expressed by the uniaxially stretched film obtained by stretching with the stretching ratio (S) set to 100%, 200%, and 300% is measured. Then, these values can be calculated by plotting them against the stretching ratio and approximating the least squares method. Further, the stretching ratio (S) is a value expressed by the following equation, where L ₀ is the distance between chucks before stretching and L ₁ is the distance between chucks after stretching.
S = {(L ₁ -L ₀ ) / L ₀ } x 100 (%)
A film-shaped or sheet-shaped molded product may be stretched for the purpose of increasing mechanical strength. In the above relational expression, the value of the slope K represents the magnitude of the change in the birefringence (Δn (S)) with respect to the stretching ratio (S), and the larger K is, the larger the amount of change in the birefringence with respect to stretching is. The smaller the value, the smaller the amount of change in birefringence with respect to stretching.
In the molded product of the present embodiment, the value of the inclination K is sufficiently smaller than that of the existing resin (for example, PMMA, PC, triacetyl cellulose resin, cyclic olefin resin, etc.). Therefore, the existing resin has a feature that the birefringence increases due to the stretching orientation during the stretching process, whereas the birefringence does not easily increase even after the stretching process.

<Refractive index>
The refractive index _dblend of the molded product of the present embodiment is preferably in the range of 1.48 to 1.53. In particular, when the obtained film is used as an optical film, it is more preferable that the refractive index _dblend is in the range of 1.48 to 1.51. If the refractive index d _blend is within this range, it can be suitably used as a polarizing plate material used in a liquid crystal television. The refractive index of the conventional polarizing plate material is, for example, 1.49 to 1.53 for the polyvinyl alcohol resin, 1.49 for the triacetyl cellulose resin, and 1. 53.

<Transparency>
The total light transmittance can be used as an index of transparency.
The total light transmittance of the molded product of the present embodiment may be appropriately optimized according to the application, but when it is used in an application where transparency is required, the total light transmittance at a thickness of 100 μm is considered from the viewpoint of visibility. The rate is preferably 80% or more. It is more preferably 85% or more, further preferably 88% or more, and particularly preferably 90% or more.
It is preferable that the total light transmittance is high, but practically, even if it is 94% or less, sufficient visibility can be ensured.
The total light transmittance can be measured according to, for example, the ISO13468-1 standard.

The molded product of this embodiment is expected to be used outdoors or in a liquid crystal television, and may be exposed to ultraviolet rays depending on the application. At this time, the transparency may decrease due to yellowing due to ultraviolet rays, and a method of adding an ultraviolet absorber to the molded product to suppress it may be used.
In that case, the light transmittance at 380 nm at a thickness of 100 μm is preferably 15% or less, more preferably 10% or less, still more preferably 8% or less.
Similarly, the light transmittance at 280 nm at a thickness of 100 μm is preferably 15% or less, more preferably 10% or less, still more preferably 8% or less.
The light transmittance of 380 nm and the light transmittance of 280 nm can be obtained by measuring the light having a wavelength of 380 nm or a wavelength of 280 nm by the same method as the measurement of the total light transmittance.

<Moldability>
The moldability can be evaluated by, for example, the difficulty of sticking to a roll for winding a film.

<Appearance>
The appearance can be evaluated, for example, by the presence or absence of air bubbles or streak unevenness in the film-formed film, or the presence or absence of silver streaks in the test piece injection-molded after being dried at 80 ° C. for 24 hours. For example, the presence or absence of air bubbles in the film can be specifically evaluated by the method described in Examples described later.

(Manufacturing method of molded product)
The molded product of the present embodiment can be manufactured by molding using the methacrylic resin composition of the present embodiment.

As a method for manufacturing the molded body, known methods such as injection molding, sheet molding, blow molding, injection blow molding, inflation molding, T-die molding, press molding, extrusion molding, foam molding, cast molding and the like can be applied. Secondary processing molding methods such as pressure forming and vacuum forming can also be used.
Further, a methacrylic resin (composition) is kneaded and manufactured using a kneader such as a heating roll, a kneader, a Banbury mixer, or an extruder, then cooled and pulverized, and further molded by transfer molding, injection molding, compression molding, or the like. Can also be mentioned as an example of a method for manufacturing a molded product.

The molded product (for example, a film) after molding may be stretched by a known method.
The molded body may be vertically uniaxially stretched in the mechanical flow direction (MD direction), laterally uniaxially stretched in the direction orthogonal to the mechanical flow direction (TD direction), or sequentially biaxially in which roll stretching and tenter stretching. Biaxial stretching may be performed by stretching by simultaneous biaxial stretching by tenter stretching, biaxial stretching by tubular stretching, inflation stretching, sequential biaxial stretching by the tenter method, or the like. By stretching, the strength of the molded product (for example, a film) can be improved.
In particular, describing the tenter method sequential biaxial stretching, in such a method, for example, a raw material resin is supplied to a single-screw or twin-screw extruder, melt-kneaded, and then a sheet extruded from a T-die is placed on a cast roll. Lead to solidify. Subsequently, the extruded sheet is introduced into the roll type longitudinal stretching machine and stretched in the mechanical flow direction (MD direction), and then the longitudinally stretched sheet is introduced into the tenter type transverse stretching machine and orthogonal to the mechanical flow direction. Stretch in the direction (TD direction). According to this tenter method sequential biaxial stretching, the stretching ratio can be easily controlled, and a molded product having a well-balanced orientation in the MD direction and the TD direction can be obtained.

The final draw ratio can be determined from the heat shrinkage rate of the obtained molded / stretched body. The draw ratio is preferably 0.1 to 400%, more preferably 10 to 400%, and even more preferably 50 to 350% in at least one direction. If it is less than the lower limit, the folding resistance tends to be insufficient, and if it exceeds the upper limit, breakage or tearing occurs frequently in the process of producing the film as a molded product, and the film tends to be continuously and stably produced. By designing within this range, it is possible to obtain a stretch-molded article that is preferable in terms of birefringence, heat resistance, and strength.

The stretching temperature is preferably Tg-30 ° C to Tg + 50 ° C. Here, the Tg (glass transition point) refers to a resin composition constituting a molded product. In order to obtain good surface properties in the obtained molded product, the lower limit of the stretching temperature is preferably (Tg-20 ° C.) or higher, more preferably (Tg-10 ° C.) or higher, still more preferably Tg or higher. It is particularly preferably (Tg + 5 ° C.) or higher, and particularly preferably (Tg + 7 ° C.) or higher. The upper limit of the stretching temperature is preferably Tg + 45 ° C. or lower, more preferably (Tg + 40 ° C.) or lower.

When the molded product of the present embodiment is used as an optical film, it is preferable to perform heat treatment (annealing) or the like after the stretching treatment in order to stabilize its optical isotropic properties and mechanical properties. The heat treatment conditions may be appropriately selected in the same manner as the heat treatment conditions performed on the conventionally known stretched film, and are not particularly limited.

Here, when the molded product of the present embodiment is used as an optical film, the target film and the film and the non-adhesive resin are co-extruded with a multilayer die, and then the non-adhesive resin layer is formed. A method of removing and obtaining only the target film can be preferably used.
This method is preferable from the viewpoints of the following (a) to (c).
(A) The film-forming stability can be improved by the heat insulating effect of the non-adhesive resin layer and the effect of improving the film strength.
(B) The effect of preventing dust, suspended matter, dust, vaporized substances such as additives, and other foreign substances in the air from adhering to the film during film formation.
(C) The effect of preventing scratches on the film surface during handling after film formation and preventing the adhesion of foreign substances such as dust.
Even if the non-adhesive resin is applied to only one side of the acrylic thermoplastic resin and co-extruded, the above effects (a) to (c) can be obtained, but both sides of the acrylic thermoplastic resin are non-adhesive. A higher effect can be obtained by sandwiching it with the resin of the above and co-extruding it.
If the solubility parameter value of the non-adhesive resin co-extruded with the multilayer die is close to the solubility parameter value of the resin constituting the film, the compatibility between the two resins becomes good and they are mixed when blended. It tends to be easy, and the resin layers that come into contact with each other when co-extruded during film formation tend to adhere to each other. Therefore, when selecting a non-adhesive resin, it is preferable to select a resin having a polarity different from that of the resin constituting the film and having a large difference in the value of the solubility parameter.
Further, at the time of co-extrusion, if the temperatures and viscosities of the two types of resins that come into contact with each other are significantly different, the layers tend to be disturbed at the interface of the resins that come into contact with each other, and a film having good transparency tends to be difficult to obtain. Therefore, when selecting a resin that is non-adhesive to the acrylic thermoplastic resin that is the main component of the film, the acrylic thermoplastic resin is used at a temperature close to the temperature of the acrylic thermoplastic resin in the die. It is preferable to select a resin having a viscosity close to that of the viscosity.
As the non-adhesive resin, a wide variety of thermoplastic resins can be used as long as the above conditions are satisfied, and preferred examples thereof include polyolefin-based resins, styrene-based resins, nylon-based resins, and fluorine-containing resins. A polyolefin-based resin is preferable, and a polypropylene-based resin is particularly preferable.

The methacrylic resin composition of the present embodiment can be suitably used as a material for various molded bodies such as optical parts such as optical films.
Applications of the molded body include, for example, household goods, OA equipment, AV equipment, battery electrical equipment, lighting equipment, tail lamps, meter covers, head lamps, light guide rods, lenses and other vehicle parts, housing applications, sanitary ware. Light guide plate, diffuser plate, polarizing plate protective film, 1/4 wavelength plate, 1/2 used for sanitary applications such as alternatives and displays such as liquid crystal displays, plasma displays, organic EL displays, field emission displays, and rear projection televisions. Examples thereof include a wavelength plate, a viewing angle control film, a retardation film such as a liquid crystal optical compensation film, a display front plate, a display substrate, a lens, a touch panel, and the like, and can be suitably used for a transparent substrate used for a solar cell and the like. .. In addition, in the fields of optical communication systems, optical exchange systems, and optical measurement systems, it can also be used for waveguides, lenses, optical fibers, optical fiber coating materials, LED lenses, lens covers, and the like. It can also be used as a modifier for other resins.

Various molded products such as films using the methacrylic resin composition of the present embodiment may be further subjected to surface functionalization treatments such as antireflection treatment, transparent conductive treatment, electromagnetic wave shielding treatment, and gas barrier treatment.

Hereinafter, specific examples and comparative examples will be described, but the present invention is not limited thereto.

[material]
The raw materials used in Examples and Comparative Examples described later are shown below.
[[Monomers constituting methacrylic resin]]
-Methyl methacrylate (MMA)
2.5 ppm of 2,4-dimethyl-6-t-butylphenol (2,4-di-methyl-6-tert-butylphenyl) manufactured by Asahi Kasei Corporation (2,4-dimethyl-6-t-butylphenol) manufactured by Chugai Trading Co., Ltd. as a polymerization inhibitor was added. What is)
-N-Phenylmaleimide (N-PMI): manufactured by Nippon Shokubai Co., Ltd.-N-cyclohexylmaleimide (N-CMI): manufactured by Nippon Shokubai Co., Ltd.-Methyl 2- (hydroxymethyl) acrylate (MHMA): manufactured by Combi Bloks

[[Organic solvent]]
・ Metaxylene: Mitsui Chemicals, Inc. ・ Toluene

[[others]]
-N-octylmercaptan (NOM): Manufactured by NOF CORPORATION, used as a chain transfer agent.
-Perhexa C-75 (EB): manufactured by NOF CORPORATION, with a purity of 75% (containing 25% ethylbenzene), used as a polymerization initiator.
Stearyl Phosphate / Distearyl Phosphate Mixture: Phoslex A-18, manufactured by Sakai Chemicals, used as a catalyst for cyclization condensation.

[[Additive]]
-ADEKA STUB PEP-36: Made by ADEKA CORPORATION, used as a phosphorus-based antioxidant.
-Irganox 1010: Made by BASF, used as a hindered phenolic antioxidant.
-Irgafos 168: Made by BASF, used as a phosphorus-based antioxidant.

Hereinafter, a method for measuring the characteristics of the methacrylic resin and the methacrylic resin composition will be described.

(I. Measurement of weight average molecular weight of methacrylic resin)
The weight average molecular weight (Mw) of the methacrylic resin produced in the production examples described below and used in the production of the methacrylic resin composition in the examples and comparative examples described later was measured with the following equipment and conditions.
-Measuring device: Gel Permeation Chromatography (HLC-8320GPC) manufactured by Tosoh Corporation
·Measurement condition:
Columns: One TSKguardcolum SuperH-H, two TSKgel SuperHM-M, and one TSKgel SuperH2500 were connected in series and used. In this column, the high molecular weight elutes quickly and the low molecular weight elutes late.
The developing solvent: tetrahydrofuran, the flow rate; 0.6 mL / min, and 0.1 g / L of 2,6-di-t-butyl-4-methylphenol (BHT) was added as an internal standard.
Detector: RI (differential refractometer) detector Detection sensitivity: 3.0 mV / min Column temperature: 40 ° C
Sample: 0.02 g Tetrahydrofuran 20 mL solution of methacrylic resin Injection amount: 10 μL
Standard sample for calibration curve: Weight peak of monodisperse The following 10 types of methyl methacrylate (PMMA Calibration Kit M-10 manufactured by Polymer Laboratories, manufactured by Polymer Laboratories) having a known molecular weight and different molecular weights were used.
Weight peak molecular weight (Mp)
Standard sample 1 1,916,000
Standard sample 2 625,500
Standard sample 3 298,900
Standard sample 4 138,600
Standard sample 5 60, 150
Standard sample 6 27,600
Standard sample 7 10,290
Standard sample 8 5,000
Standard sample 9 2,810
Standard sample 10 850
Under the above conditions, the RI detection intensity with respect to the elution time of the methacrylic resin was measured.
The weight average molecular weight (Mw) of the methacrylic resin was determined based on the area area on the GPC elution curve and the calibration curve of the cubic approximation formula.

(II. Measurement of composition of monomer unit)
For the methacrylic resin produced in the production example described later, NMR and FT-IR measurements were carried out, and the composition of the monomer unit and the structural unit was confirmed.
NMR: JNM-ECA500 manufactured by JEOL Ltd.
FT-IR: manufactured by JASCO Corporation, IR-410, ATR method (Dura Scope (ATR crystal: diamond / ZnSe), resolution: 4 cm ^-1 ) was used.

(III. Measurement of glass transition temperature)
The methacrylic resin produced in the production example described later was measured in accordance with ASTM-D-3418 using a thermal analyzer (Diamond DSC manufactured by PerkinElmer), and the glass transition temperature (° C.) was measured by the midpoint method. ) Was calculated.

Hereinafter, a method for evaluating the characteristics of the methacrylic resin composition, pellets, and film will be described.

<1. Weight average molecular weight>
The weight average molecular weight of the methacrylic resin compositions of Examples and Comparative Examples described later was determined in the same manner as in the above-mentioned method for measuring the weight average molecular weight of the methacrylic resin. The results are shown in Table 1.

<2. Measurement of glass transition temperature>
The glass transition temperature of the methacrylic resin composition of Examples and Comparative Examples described later was calculated in the same manner as the method for measuring the glass transition temperature of the methacrylic resin described above. The results are shown in Table 1.

<3. Content of the number of foreign substances>
After granulating 5 tons of pellets of the methacrylic resin composition of Examples and Comparative Examples described later, a pellet sample is collected, and the particle size contained in 1 gram of the pellet is 10 μm or more and less than 20 μm under the following measuring equipment and measurement conditions. The number of foreign substances and the number of foreign substances having a particle diameter of 20 μm or more were measured.
Measuring equipment: Particle counter SVSS-C for liquid manufactured by PAMAS, Germany
Sensor specifications: Model HCB-LD-50 / 50 (particle size range 1.0-450 μm)
Sample flow rate: 10 mL / min
Sample volume: 10 mL
Reference capacity: 10 mL
Sample concentration: 0.05 g / mL
Sample preparation: Dissolve 12.5 g of pellets in 250 mL of chloroform Number of repetitions: 2 times (The first data was deleted and the average value of the second and third data was adopted).
The measurement results of the number of foreign substances were evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1.
(Evaluation criteria)
〇: The number of foreign substances contained in 1 gram of pellets is 50 or less Δ: The number of foreign substances contained in 1 gram of pellets is more than 50 and 100 or less ×: The number of foreign substances contained in 1 gram of pellets is more than 100

<4. Thermal stability evaluation>
(4-a) Weight loss rate when held at 280 ° C. for 0.5 hours (Air atmosphere)
The methacrylic resin compositions obtained in Examples and Comparative Examples described later were weighed under the following setting conditions, and the weight loss rate (%) when held at about 280 ° C. for 30 minutes was calculated. The evaluation results are shown in Table 1.
Measuring device: Differential thermal balance Thermo plus EVO II TG8120 (manufactured by Rigaku Co., Ltd.)
Sample amount: Approximately 10 mg
Measurement atmosphere: air (100 mL / min)
Measurement conditions: Hold at 50 ° C for 2 minutes, raise the temperature to 200 ° C at 20 ° C / min, raise the temperature to 250 ° C at 10 ° C / min, raise the temperature to the set temperature of 275 ° C at 10 ° C / min, and raise the temperature to 275 ° C. The temperature was maintained at ° C. for 30 minutes, and the weight loss rate (%) after 30 minutes from the start of holding was calculated. When the set temperature was 275 ° C, the measured temperature was about 280 ° C.

(4-b) Weight loss rate when held at 280 ° C. for 1 hour (nitrogen atmosphere)
The methacrylic resin compositions obtained in Examples and Comparative Examples described later were weighed under the following setting conditions, and the weight loss rate (%) when held at about 280 ° C. for 60 minutes was calculated. The evaluation results are shown in Table 1.
Measuring device: Differential thermal balance Thermo plus EVO II TG8120 (manufactured by Rigaku Co., Ltd.)
Sample amount: Approximately 10 mg
Measurement atmosphere: Nitrogen (100 mL / min)
Measurement conditions: Hold at 50 ° C for 2 minutes, raise the temperature to 200 ° C at 20 ° C / min, raise the temperature to 250 ° C at 10 ° C / min, raise the temperature to the set temperature of 275 ° C at 10 ° C / min, and raise the temperature to 275 ° C. The temperature was maintained at ° C. for 60 minutes, and the weight loss rate (%) after 60 minutes from the start of holding was calculated. When the set temperature was 275 ° C, the measured temperature was about 280 ° C.

<5. Continuous productivity>
(5-a) Extrusion stability (rate of pressure increase after 48 hours)
When the methacrylic resin composition was produced by an extruder in Examples and Comparative Examples described later, the pressures 1 hour and 48 hours after the start of extrusion were measured, respectively, and the pressure increase rate was calculated. The calculated pressure increase rate was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1.
(Evaluation criteria)
⊚: Pressure increase rate is 5% or less ○: Pressure increase rate is more than 5% and 8% or less △: Pressure increase rate is more than 8% and less than 10% ×: Pressure increase rate is 10% or more

(5-b) Pellet particle size distribution (weight ratio of 8 mesh residual pellets)
Pellets were sieved under the following setting conditions using an electric vibrating sieve. As the sieve, a standard sieve manufactured by Tokyo Screen conforming to JIS Z8801 was used. As for the sieve, the ones with large openings were installed one by one at the top, and the ones with small ones were installed at the bottom, and the saucer was used at the bottom.
The weight remaining on the 2.36 mm mesh sieve was divided by the weight used for measurement to calculate the pellet weight ratio (%) remaining on the 2.36 mm sieve, and the pellet particle size distribution was evaluated. The evaluation results are shown in Table 1.
Equipment used: Electric vibrating sieve Manufacturer: Mitamura RIKEN INDUSTRY CO., LTD.
Model name: SIEVE SHAKER
Vibration force scale (0 to 100): 60
Vibration time: 10 minutes Number of sieve stages: 5 stages Used sieve mesh opening: 3.35 mm (6 mesh), 2.36 mm (8 mesh), 1.70 mm (10 mesh), 1.18 mm (14 mesh), saucer measurement amount : Approximately 100g

<6. Color: Whiteness>
The methacrylic resin composition obtained in Examples and Comparative Examples described later was subjected to an injection molding machine (EC-100SX, manufactured by Toshiba Machine Co., Ltd.) under the conditions of a molding temperature of 280 ° C. and a mold temperature of 60 ° C. to a thickness. A test piece having a size of 3 mm, a width of 20 mm, and a length of 220 mm was formed. As the test piece, 4 shots after discarding 20 shots from the resin switching were used for measurement.
Using a color difference meter TC-8600A manufactured by Nippon Denshoku Industries Co., Ltd., four test pieces were stacked and the whiteness W in the length direction of 220 mm was measured in accordance with JIS-P8123. The measurement result of whiteness W was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1.
(Evaluation criteria)
⊚: Whiteness W is 50 or more ○: Whiteness W is 40 or more and less than 50 ×: Whiteness W is less than 40

<7. Appearance: Number of bubbles in the film>
Using the methacrylic resin compositions obtained in Examples and Comparative Examples described later, an extruder (manufactured by Plastic Engineering Laboratory, φ32 mm single-screw extruder) (L / D = 32, number of vents: 1) was used. A film having a thickness of about 100 μm and a width of about 12 cm was produced at a set temperature: 290 ° C. and a roll temperature: (glass transition temperature −10 ° C.). The resin and the resin composition used were previously dried in an oven set at 105 ° C. for 24 hours.
About 5 minutes after the temperature became stable, a total of 10 films of about 20 cm were cut out from the produced film. Then, the surface of each film was observed using an optical microscope, the number of bubbles having a major axis of 100 μm or more contained in 100 cm ² of the film was counted for each film, and the average value of the 10 sheets was calculated. The evaluation results are shown in Table 1.

Hereinafter, production examples of the methacrylic resin will be described.

[Manufacturing Example 1]
432.3 kg of methyl methacrylate (MMA), 33.0 kg of N-phenylmaleimide (N) in a 1.25 m ³ reaction kettle equipped with a stirrer equipped with paddle wings, a temperature sensor, a cooling tube, and a nitrogen introduction tube. -PMI), 84.7 kg of N-cyclohexylmaleimide (N-CMI), 450.0 kg of metaxylene, and 0.28 kg of n-octyl mercaptan were charged and dissolved to prepare a raw material solution. The temperature was raised to 125 ° C. with stirring while passing nitrogen through it.
Separately, an initiator feed solution was prepared by mixing 0.23 kg of perhexa C-75 and 1.82 kg of metaxylene.
When the raw material solution reached 127 ° C., the feed (addition) of the initiator feed solution (polymerization initiator mixture) was started with the profiles (1) to (6).
(1) 0.0 to 0.5 hours: Feed rate 1.00 kg / hour (2) 0.5 to 1.0 hours: Feed rate 0.50 kg / hour (3) 1.0 to 2.0 hours: Feed rate 0.42 kg / hour (4) 2.0 to 3.0 hours: Feed rate 0.35 kg / hour (5) 3.0 to 4.0 hours: Feed rate 0.14 kg / hour (6) 4. 0 to 7.0 hours: Feed rate 0.13 kg / hour After feeding the initiator for a total of 7 hours (B time = 7 hours), the reaction was continued for another 1 hour, and 8 hours from the start of addition of the initiator. The polymerization reaction was carried out until later.
During the polymerization reaction, the internal temperature was controlled at 127 ± 2 ° C. When the polymerization conversion rate of the obtained polymerization solution was measured, it was MMA unit: 93.7% by mass, N-PMI unit: 95.5% by mass, and N-CMI unit: 91.2% by mass. Overall, the polymerization conversion was 93%.
The polymer solution obtained above was subjected to a volatilization treatment at 140 rpm and 10 kg / hour in terms of resin amount using a φ42 mm devolatilization extruder with 4 fore vents and 1 back vent to obtain resin pellets.
The weight average molecular weight of the obtained pellets was 150,000, and the glass transition temperature was 135 ° C.
The composition determined by NMR was MMA unit: 79% by mass, N-PMI unit: 6% by mass, and N-CMI unit: 15% by mass.

[Manufacturing Example 2]
41.0 kg of methyl methacrylate (MMA) and 10.0 kg of methyl 2- (hydroxymethyl) acrylate in a 200 L reaction kettle equipped with a stirrer equipped with paddle wings, a temperature sensor, a condenser, and a nitrogen introduction tube. (Manufactured by Combi Blocks), 50.0 kg of toluene was charged to prepare a raw material solution. The liquid temperature was raised to 107 ° C. with stirring while passing nitrogen through it.
Separately, an initiator feed solution was prepared by mixing 0.05 kg of Perhexa C-75 and 0.36 kg of toluene.
When the temperature of the raw material solution reached 107 ° C., the feed of the initiator feed solution was started with the profiles (1) to (4).
(1) 0.0 to 0.5 hours: Feed rate 0.20 kg / hour (2) 0.5 to 1.0 hours: Feed rate 0.10 kg / hour (3) 1.0 to 3.0 hours: Feed rate 0.075 kg / hour (4) 3.0 to 7.0 hours: Feed rate 0.028 kg / hour After feeding the initiator for a total of 7 hours (B time = 7 hours), react for another 1 hour. The polymerization reaction was completed over a total of 8 hours.
During the polymerization reaction, the internal temperature was controlled at 107 ± 2 ° C. To the obtained polymer solution, 51 g of a stearyl phosphate / distearyl phosphate mixture was added, and a cyclization condensation reaction was carried out under reflux (about 90 to 110 ° C.) for 5 hours.
The obtained polymer solution was subjected to a cyclization condensation reaction and a volatilization treatment at 140 rpm and 10 kg / hour in terms of resin amount using a φ42 mm twin-screw devolatilization extruder with 4 fore vents and 1 back vent to prepare resin pellets. Obtained. The composition of the obtained resin was MMA unit: 82% by mass, lactone ring structure unit: 17% by mass, MHMA unit: 1% by mass, a weight average molecular weight of 130,000, and a glass transition temperature of 129 ° C.

A methacrylic resin composition and a film were produced using the methacrylic resin produced according to each of the above-mentioned production examples.

(Example 1)
PEP-36: 0.1 part by mass and Irganox 1010: 0.1 part by mass are blended with 100 parts by mass of the resin obtained in Production Example 1, and a screw with a vent (3 places) manufactured by Toshiba Machine Co., Ltd. A pleated filter manufactured by Fuji Filter Co., Ltd. equipped on the extruder by melt-kneading with a twin-screw extruder TEM-48SS (L / D = 32) with a diameter of Φ48 mm at a discharge rate of 180 kg / hour and a screw rotation speed of 300 rpm. Foreign matter is removed through (element quantity: 4, element diameter: φ60 mm × 500 mm, filtration accuracy: 15 μm) and extruded through a 16-hole die (die temperature: 260 ° C.) to form a pellet-shaped methacrylic resin composition (hereinafter, Resin composition pellets) were obtained. The temperature of the resin coming out of the hole of the die was measured with a resin thermometer and shown in Table 1 as the resin temperature (resin temperature: 280 ° C.).
The above physical property evaluation was carried out using the resin composition pellets thus obtained and the film formed by using the pellets.
Table 1 shows the details of the blending amount of the methacrylic resin and the additive, the conditions such as melt-kneading and extrusion, and the evaluation results.

(Examples 2 to 5, Comparative Examples 1 to 6)
Using the conditions of the resin and additives shown in Table 1, melt kneading, extrusion, etc., resin composition pellets and films were obtained in the same manner as in Example 1, and the above physical property evaluation was carried out. The evaluation results are shown in Table 1.
As shown in Table 1, the polymer filter was not used in Comparative Examples 2 and 3, and in Comparative Examples 4 to 6, a leaf disk filter (manufactured by Fuji Filter Co., Ltd., element quantity: 40 sheets) was used instead of the pleated filter. , Element diameter: 8.8 inches, filtration accuracy: 15 μm) was used.

As shown in Table 1, the methacrylic resin compositions of Examples, which contain the methacrylic resin specified in the present application, have a glass transition temperature within a predetermined range, and are produced under suitable melt extrusion conditions using a pleated filter, are: The content of minute foreign substances with a particle size of 10 μm or more and less than 20 μm is very small, and the content of relatively large foreign substances with a particle size of 20 μm or more is also very small. You can see that the appearance is also excellent. It is also found that the use of the pleated filter suppresses the decomposition of the resin and prevents the decrease in the weight average molecular weight.

INDUSTRIAL APPLICABILITY The present invention comprises a methacrylic resin composition, a method for producing the methacrylic resin composition, and a method for producing the methacrylic resin composition, which are excellent in continuous productivity, have a low content of foreign substances, and can produce a molded product having excellent physical properties and appearance. Pellets and molded products containing the methacrylic resin composition can be provided.
The present invention relates to household goods, OA equipment, AV equipment, battery electrical equipment, lighting equipment, tail lamps, meter covers, head lamps, light guide rods, lenses and other vehicle member applications, housing applications, sanitary ceramic substitutes and other sanitary applications. Light guide plate, diffuser plate, polarizing plate protective film, 1/4 wavelength plate, 1/2 wavelength plate, viewing angle used for displays such as liquid crystal displays, plasma displays, organic EL displays, field emission displays, and rear projection televisions. Phase difference films such as control films and liquid crystal optical compensation films, transparent substrates such as display front panels, display substrates, lenses and touch panels, transparent substrates used for decorative films and solar cells, optical communication systems, optical exchange systems, etc. In the field of optical measurement systems, it has industrial potential as a waveguide, a lens, an optical fiber, a coating material for an optical fiber, an LED lens, a lens cover, and the like.

Claims (16)

It contains 50% by mass or more of the methacrylic acid ester monomer unit (A), and has a maleimide-based structural unit (B-1), a glutaric acid anhydride-based structural unit (B-2), and a glutaric acid-based structural unit (B-). 3), and a methacrylic resin containing a structural unit (B) having a ring structure in at least one main chain selected from the group consisting of the lactone ring structural unit (B-4) .
The glass transition temperature is 110-160 ° C.
The weight loss rate when heated at 280 ° C. for 1 hour in a nitrogen atmosphere as measured by thermogravimetric analysis is 5% or less.
Measured with a particle counter, it contains 100 or less foreign substances having a particle size of 10 μm or more and less than 20 μm per 1 g , and contains 100 or less foreign substances having a particle size of 20 μm or more per 1 g .
A methacrylic resin composition characterized by this. The methacrylic resin composition according to claim 1, wherein the weight loss rate when heated at 280 ° C. for 0.5 hours in air, which is measured by thermogravimetric analysis, is 20% or less. The methacrylic resin composition according to claim 1 or 2 , wherein the number of bubbles having a major axis of 100 μm or more contained in 100 cm ² of the film formed by an extruder having a set temperature of 290 ° C. is less than five. The methacrylic resin composition according to any one of claims 1 to 3 , which contains 95% by mass or more of the methacrylic resin. With respect to 100 parts by mass of the methacrylic resin, 0.01 to 2 parts by mass of a hindered phenol-based antioxidant is contained, and a total of 0.01 to 2 parts of a phosphorus-based antioxidant and / or a sulfur-based antioxidant is contained. The methacrylic resin composition according to any one of claims 1 to 4 , which comprises a part by mass. The methacrylic resin composition according to any one of claims 1 to 5 , wherein the glass transition temperature of the methacrylic resin is 110 ° C. or higher and 160 ° C. or lower. The methacrylic resin has the (A) monomer unit: 50 to 97% by mass, the structural unit (B) having a ring structure in the main chain: 3 to 30% by mass, and the methacrylic ester monomer. The methacrylic resin composition according to any one of claims 1 to 6 , which comprises another polymerizable vinyl-based monomer unit (C): 0 to 20% by mass. The (C) monomer unit is an aromatic vinyl-based monomer unit (C-1), an acrylic acid ester monomer unit (C-2), and a vinyl cyanide-based monomer unit (C-3). The methacrylic resin composition according to claim 7 , which comprises at least one monomer unit selected from the group consisting of). The methacrylic system according to claim 8 , wherein the (C) monomer unit contains at least one monomer unit selected from the group consisting of a methyl acrylate unit, an ethyl acrylate unit, a styrene unit, and an acrylonitrile unit. Resin composition. The methacrylic resin composition according to any one of claims 1 to 9 , which contains 0.01 to 5 parts by mass of an ultraviolet absorber with respect to 100 parts by mass of the methacrylic resin. A pellet comprising the methacrylic resin composition according to any one of claims 1 to 10 . It contains 50% by mass or more of the methacrylic acid ester monomer unit (A), and has a maleimide-based structural unit (B-1), a glutaric acid anhydride-based structural unit (B-2), and a glutaric acid-based structural unit (B-). It contains a methacrylic resin containing a structural unit (B) having a ring structure in at least one main chain selected from the group consisting of 3) and a lactone ring structural unit (B-4), and has a glass transition temperature of 110 to 160. A method for producing a methacrylic resin composition at ° C.
Including the step of extruding a methacrylic resin composition from a die using an extruder equipped with a feeder, a vent port and a pleated filter .
When extruding with the extruder, the discharge amount (discharge amount / number of holes) of the methacrylic resin composition per hour per hole of the die is 5 kg / (hr / piece) or more and 30 kg / (hr / piece). A method for producing a methacrylic resin composition, which comprises the following. A molded product comprising the methacrylic resin composition according to any one of claims 1 to 10 . The molded product according to claim 13 , which is an optical component. The molded product according to claim 13 , which is an optical film. The molded body according to claim 13 , which is a member for a vehicle.

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