JP2019077866A - Methacrylic resin composition, and molded body - Google Patents

Abstract

To provide a methacrylic resin composition which has good infrared absorption ability, and is excellent in long-term stability, long-term heat-resistant stability, and long-term wet heat stability, to outdoor environment that is exposed to ultraviolet rays, and a molded body.SOLUTION: A methacrylic resin composition contains a methacrylic resin (A) having a weight average molecular weight Mw of 70,000 to 200,000, an ultraviolet absorber (B), a phosphoric acid stabilizer (C), a hindered phenol stabilizer (D) and an infrared absorber (E).SELECTED DRAWING: None

Description

  The present invention relates to a methacrylic resin composition.

  A methacrylic resin composition is characterized in that it has higher light transmittance, weatherability and rigidity as a transparent resin than other plastic transparent resins, and conventionally, members for electric and electronic devices, members for batteries, members for vehicles, lighting It is used in a wide range of applications such as fixtures, building materials, signs, nameplates, pictures, windows of display devices, etc. Among them, due to high light transmittance, high appearance, and good weather resistance, they are often used as members for electric and electronic parts, parts for vehicles, and lighting fixtures.

  Light in the infrared region contained in sunlight or light from light sources such as fluorescent lamps and lamps as protective materials for roofs such as buildings, cars, trains, and buses, and lighting devices and billboards (hereinafter referred to as “heat ray” There is a demand for a resin molded product having a property (hereinafter abbreviated as “heat ray shielding property”) for blocking “abbreviated as“ (hereinafter abbreviated as “heat ray shielding property”) and having a high total light transmittance in the visible light region. Moreover, it is requested | required of the resin molding that it is excellent in the weather resistance at the time of outdoor use. However, if the infrared absorber that secures the heat ray shielding property is exposed to heat for a long time, exposed to direct sunlight for a long time, or exposed to heat containing humidity near practical conditions for a long time, the infrared absorber There is a problem that it denatures and the effect can not be exhibited sufficiently.

Further, in recent years, as a new effect brought about by heat ray shielding, there is an antifogging effect in a vehicle lamp and the like. In a molded body having a space inside when members such as a vehicle lamp are combined, water vapor is released from the moisture-absorbed methacrylic resin, and the water vapor is cooled by some external factor to cause dew condensation to occur. The problem is that the inside looks cloudy when you look at the
In order to solve this problem, a technique for preventing fogging by applying an antifogging paint to the inside of a molded body as in Patent Document 1 has been proposed, but if the amount of released water vapor is large, condensation may occur. There is a problem that the mark from which the water droplet drips remains and the appearance becomes poor. Moreover, when the anti-fog coating material is apply | coated depending on the methacrylic resin composition to be used, the component contained in the methacrylic resin composition bleeds out, and the subject that an appearance defect was produced occurred. Therefore, development of the methacrylic resin composition which exhibits an antifogging effect without appearance defect is desired.
In order to solve this problem, a vehicle lamp using a methacrylic resin composition containing an infrared absorber as in Patent Document 2 has been proposed, but it may be exposed to heat for a long time, or may be exposed to direct sunlight for a long time When exposed or exposed to heat containing humidity close to practical conditions for a long time, the problem remains that the infrared absorber is denatured and the effect can not be sufficiently exerted.

Patent Document 3 discloses a heat absorbing polymer composition comprising a transparent thermoplastic synthetic material containing tungsten oxide doped with cesium as an inorganic IR absorber and a phosphine stabilizer. In the examples, a sheet made of a polycarbonate resin containing tungsten oxide doped with cesium is disclosed. However, in the polycarbonate resin plate described in Patent Document 3, since the injection molding to the polycarbonate resin plate is performed at a high temperature of 300 ° C., the tungsten oxide particles doped with cesium are thermally decomposed to have the heat absorption characteristics of the resin plate and all The light transmittance decreases and turns yellow. Moreover, since it is a resin board which consists of polycarbonate resin, its weather resistance is also inadequate.
Patent document 4 discloses that an antioxidant such as a phosphite, a hindered phenol, an aromatic, an aliphatic or mixed phosphine, a lactone, a thioether, for improving processing stability to a naphthalocyanine or phthalocyanine contained in a polycarbonate resin. And that it can contain hindered amines etc., but since the melting and kneading of the organic IR absorber to the polycarbonate resin are performed at a high temperature of 300.degree. C., the organic IR absorber is thermally decomposed and the heat absorption characteristics of the resin plate or The total light transmittance decreases. Moreover, since it is a resin board which consists of polycarbonate resin, its weather resistance is also inadequate.
Patent Document 5 discloses a (meth) acrylic resin composition having high total light transmittance and heat ray shielding properties and good machinability. Although a (meth) acrylic resin composition is used to improve the weather resistance, the weather resistance is not sufficient, and when exposed to ultraviolet light for a long period of time, the infrared absorber is denatured, The total light transmittance is greatly reduced. In addition, the long-term characteristics of the infrared absorber against moist heat were not sufficient.

Japanese Patent Application Laid-Open No. 2003-7105 JP-A-2016-162637 Patent No. 579 5326 Japanese Patent Publication No. 2003-508615 JP-A-2017-122176

  Therefore, the present invention is to provide a methacrylic resin composition and a molded article which are excellent in infrared absorptivity, long-term stability to an outdoor environment exposed to ultraviolet light, long-term heat stability and long-term moist heat stability. With the goal.

  As a result of intensive studies to solve the problems of the prior art described above, the present inventors find that the problems of the prior art can be solved in a methacrylic resin composition having a specific composition, and complete the present invention It came to

That is, the present invention is as follows.
[1]
Methacrylic resin (A) having a weight average molecular weight Mw of 70,000 to 200,000, ultraviolet absorber (B), phosphoric acid stabilizer (C), hindered phenol stabilizer (D), and infrared absorption The methacrylic resin composition containing an agent (E).
[2]
The infrared absorber (E) is tungsten oxide and / or lanthanum hexaboride,
The methacrylic resin composition [3] according to [1], wherein the content of the infrared absorber (E) is 0.002 to 0.05 parts by mass with respect to 100 parts by mass of the methacrylic resin (A) ]
0.01 to 0.3 parts by mass of the ultraviolet absorber (B) and 0.03 to 0.5 parts by mass of the phosphoric acid stabilizer (C) relative to 100 parts by mass of the methacrylic resin (A) The methacrylic resin composition according to [1] or [2], which contains 0.03 to 0.5 parts by mass of the hindered phenol stabilizer (D).
[4]
In any one of [1] to [3], the melting point of the ultraviolet absorber (B), the phosphoric acid stabilizer (C), and the hindered phenol stabilizer (D) is 90 ° C. or higher The methacrylic resin composition as described in a statement.
[5]
The methacrylic resin composition according to any one of [1] to [4], wherein the hindered phenol stabilizer (D) has at least one ring structure containing an oxygen atom or a nitrogen atom in the molecule. .
[6]
The molded object characterized by including the methacrylic resin composition in any one of [1]-[5].
[7]
The molded object as described in [6] used for the member for construction, the member for electric / electronics, the member for vehicles, and the member for illumination.
[8]
The molded object as described in [7] used for the member for vehicle lamps.

  According to the present invention, it is possible to obtain a methacrylic resin composition and a molded article which are excellent in infrared absorptivity, long-term stability to an outdoor environment exposed to ultraviolet light, long-term heat stability and long-term wet heat stability.

Hereinafter, a mode 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 within the scope of the gist thereof Various modifications are possible.
In the following, the constituent unit constituting the polymer forming the methacrylic resin of the present embodiment will be referred to as "--monomer unit" and / or a plurality of "--monomer units". It is called "structural unit".
Moreover, the thing of the constituent material of this "-monomer unit" may abbreviate | omit a "unit", and may only describe it as "-monomer."

<Methacrylic resin composition>
The methacrylic resin composition of the present embodiment is a methacrylic resin (A) having a weight average molecular weight Mw of 70,000 to 200,000, an ultraviolet light absorber (B), a phosphoric acid stabilizer (C), and a hindered resin. It is characterized by containing a phenolic stabilizer (D) and an infrared absorber (E).

<Methacrylic resin (A)>
The methacrylic resin (A) contained in the methacrylic resin composition of the present embodiment contains 80 to 99.9% by mass of a methacrylic acid ester monomer unit and a vinyl monomer capable of being copolymerized with the methacrylic acid ester monomer. It is preferable to contain 0.1 to 20% by mass of vinyl monomer units consisting of a body.
The methacrylic resin (A) may be a single methacrylic resin, or may be a combination of two or more methacrylic resins.

Examples of the methacrylic acid ester monomer constituting the methacrylic acid ester monomer unit contained in the methacrylic resin (A) include, but are not limited to, butyl methacrylate, ethyl methacrylate, and methacrylic acid. Methyl, propyl methacrylate, isopropyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, methacrylic acid (2-ethylhexyl), methacrylic acid (t-butylcyclohexyl), benzyl methacrylate, methacrylic acid (2,2,2-trifluoro) Ethyl) and the like. From the viewpoint of availability and price, methyl methacrylate and ethyl methacrylate are preferred.
The methacrylic acid ester monomers may be used alone or in combination of two or more.

  The content of the methacrylic acid ester monomer unit is preferably 80 to 99.9% by mass, and more preferably 82 to 99.8% by mass, based on the methacrylic resin (A). More preferably, it is 99.5% by mass. When the content of the methacrylic acid ester monomer unit is 99.9% by mass or less, decomposition of the resin at the time of molding can be prevented, and generation of a methacrylic acid ester monomer as a volatile component or molding failure called silver is caused. Can be effectively prevented. In addition, when the methacrylic acid ester monomer unit is 80% by mass or more, the heat resistance generally required for a molded article can be secured. By having sufficient heat resistance, rigidity can also be ensured, and strength generally required as a molded article can be ensured.

The vinyl monomer copolymerizable with the methacrylic acid ester monomer contained in the methacrylic resin (A) is not limited to the following, for example, methyl acrylate, ethyl acrylate, acrylic acid An acrylic acid ester monomer having one acrylate group such as n-propyl, n-butyl acrylate, sec-butyl acrylate, 2-ethylhexyl acrylate and the like can be mentioned.
In addition, ethylene glycol such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate having two or more (meth) acrylate groups Or those obtained by esterifying both terminal hydroxyl groups of the oligomer with acrylic acid or methacrylic acid; hydroxyl groups of two alcohols such as neopentyl glycol di (meth) acrylate and di (meth) acrylate esterified with acrylic acid or methacrylic acid And acrylic acid ester monomers such as those obtained by esterifying polyhydric alcohol derivatives such as trimethylolpropane and pentaerythritol with acrylic acid or methacrylic acid.
In particular, methyl acrylate, ethyl acrylate and n-butyl acrylate are preferable, and methyl acrylate and ethyl acrylate are more preferable from the viewpoint of availability.
One of these may be used alone, or two or more may be used in combination.

The content of the vinyl monomer unit composed of a vinyl monomer copolymerizable with the methacrylic acid ester monomer is preferably 0.1 to 20% by mass with respect to the methacrylic resin (A), 0 It is more preferable that it is 2.2-18 mass%, and it is further more preferable that it is 0.5-16 mass%. By being 0.1 mass% or more, decomposition of the resin at the time of molding can be prevented, and generation of a methacrylic acid ester monomer which is a volatile component and molding defects called silver can be effectively prevented. Moreover, the heat resistance generally required for a molded article can be ensured by a vinyl monomer unit being 20 mass% or less.
In addition, the content of the vinyl monomer unit is 0.4 mass, particularly when a monomer having two (meth) acrylate groups is used with respect to the methacrylic resin (A) (100 mass%). % Or less, when using a monomer having three (meth) acrylate groups, use at 0.25% by mass or less uses a monomer having four or more (meth) acrylate groups In the case of use, the use of 0.15% by mass or less is preferable from the viewpoint of securing the flowability during injection molding and maintaining the transparency.

  Moreover, as vinyl monomers other than acrylic acid ester monomers copolymerizable with the above-mentioned methacrylic acid ester monomer, although it is not limited to the following, for example, acrylic acid, methacrylic acid, etc. Α, β-unsaturated acids of the following: unsaturated group-containing divalent carboxylic acids such as maleic acid, fumaric acid, itaconic acid, cinnamic acid and their alkyl esters; styrene, o-methylstyrene, m-methylstyrene, p- Methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, о-ethylstyrene, p-tert- Styrene-based monomers such as butylstyrene and isopropenylbenzene (α-methylstyrene); 1-vinylnaphthalene, 2-vinylnaphthalene, Aromatic vinyl compounds such as 1,1-diphenylethylene, isopropenyltoluene, isopropenylethylbenzene, isopropenylpropylbenzene, isopropenylbutylbenzene, isopropenylpentylbenzene, isopropenylhexylbenzene, isopropenyloctylbenzene, etc .; acrylonitrile, methacrylonitrile Vinyl cyanide compounds such as: unsaturated carboxylic acid anhydrides such as maleic anhydride and itaconic anhydride; maleimide, N-methyl maleimide, N-ethyl maleimide, N-phenyl maleimide, N-cyclohexyl maleimide and the like N- Examples thereof include substituted maleimides; amides such as acrylamide and methacrylamide; and polyfunctional monomers such as divinylbenzene.

In the methacrylic resin (A), for the purpose of improving the properties such as heat resistance and molding processability, vinyl monomers other than the above exemplified vinyl monomers may be appropriately added and copolymerized. Good.
The acrylic acid ester monomer copolymerizable with the above-mentioned methacrylic acid ester monomer, and vinyl monomers other than the exemplified acrylic acid ester monomer may be used alone or in combination. It may be used in combination of species or more.

<Weight-average molecular weight of methacrylic resin (A)>
The weight average molecular weight (Mw) of the methacrylic resin (A) contained in the methacrylic resin composition of the present embodiment will be described.
The methacrylic resin (A) has a weight average molecular weight (Mw) of 70,000 to 200,000 as measured by GPC (gel permeation chromatography).
In order to obtain excellent mechanical strength and solvent resistance, the lower limit of the weight average molecular weight (Mw) of the methacrylic resin (A) is preferably 75,000 or more, more preferably 80,000 or more, 85,000 The above is more preferable.
Moreover, in order that a methacrylic resin composition may show favorable fluidity | liquidity, 198,000 or less is preferable and, as for the upper limit of the weight average molecular weight (Mw) of methacrylic resin (A), 195,000 or less is more preferable, 190,000 or less is even more preferred.
When the weight average molecular weight (Mw) of the methacrylic resin (A) is in the range of 70,000 to 200,000, it is possible to balance the flowability, the mechanical strength and the solvent resistance, which is favorable. Molding processability is maintained.

The molecular weight distribution (Mw / Mn) of the methacrylic resin (A) contained in the methacrylic resin composition of the present embodiment is preferably 1.0 to 6.0, and is 1.0 to 5.5. Is more preferably 1.0 to 5.0. When the molecular weight distribution (Mw / Mn) of the methacrylic resin (A) is 1.0 to 6.0, the physical properties developed by the methacrylic resin (A) are stabilized.
Here, Mw represents a weight average molecular weight, and Mn represents a number average molecular weight.
The weight-average molecular weight (Mw) and the number-average molecular weight (Mn) of the methacrylic resin (A) can be measured by GPC, and specifically, they can be measured by the method described in the following Examples. it can.
Specifically, a calibration curve is prepared from elution time and weight average molecular weight using a standard methacrylic resin which is known as a monodispersed weight average molecular weight in advance and available as a reagent, and an analysis gel column in which high molecular weight components are eluted first. Keep it. Subsequently, based on the calibration curve obtained, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the predetermined methacrylic resin (A) to be measured can be determined, whereby the molecular weight distribution (Mw / Mn) Can be calculated. The number average molecular weight (Mn) is the average of the molecular weight per simple molecule, and is defined by the total weight of the system / the number of molecules in the system. The weight average molecular weight (Mw) is defined as the average of the molecular weight by weight fraction.

<Content of methacrylic resin (A)>
The content of the methacrylic resin (A) is preferably 75 to 99.9% by mass, and more preferably 80 to 99.8% by mass, with respect to 100% by mass of the methacrylic resin composition. It is further more preferable that it is-99.7 mass%.

<Method for producing methacrylic resin (A)>
The methacrylic resin (A) contained in the methacrylic resin composition of the present embodiment can be produced by a solution polymerization method, a bulk polymerization method, a cast polymerization method, a suspension polymerization method, but in the case of being limited to these methods Absent. Preferred is bulk polymerization, solution polymerization, suspension polymerization, and more preferred is suspension polymerization. By selecting the suspension polymerization, small spherical polymers of 0.5 μm to 5 mm can be obtained, and when the resin composition is produced as in the present invention, the additives can be well dispersed.
The polymerization temperature may be appropriately selected according to the polymerization method, but is preferably 50 ° C. or more and 100 ° C. or less, and more preferably 60 ° C. or more and 90 ° C. or less.

When manufacturing methacrylic resin (A), you may use a polymerization initiator. The polymerization initiator is not limited to the following, but when radical polymerization is carried out, for example, di-t-butyl peroxide, lauroyl peroxide, stearyl peroxide, benzoyl peroxide, t-butyl peroxy Neodecanate, t-butylperoxypivalate, dilauroyl peroxide, dicumyl peroxide, t-butylperoxy-2-ethylhexanoate, 1,1-bis (t-butylperoxy) -3, Organic peroxides such as 3,5-trimethylcyclohexane and 1,1-bis (t-butylperoxy) cyclohexane, azobisisobutyronitrile, azobisisovaleronitrile, 1,1-azobis (1-cyclohexane Carbonitrile), 2,2'-azobis-4-methoxy-2,4-azobis General radical polymerization initiators of azo type such as isobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 2,2'-azobis-2-methylbutyronitrile and the like can be mentioned. One of these may be used alone, or two or more of them may be used in combination. These radical polymerization initiators and a suitable reducing agent may be combined and used as a redox initiator.
These radical polymerization initiators and / or redox initiators are used in a range of 0 to 1 parts by mass with respect to 100 parts by mass of the total amount of all monomers used in the polymerization of the methacrylic resin (A). In general, the temperature can be selected appropriately in consideration of the temperature at which the polymerization is performed and the half life of the polymerization initiator.

When a bulk polymerization method, a cast polymerization method, or a suspension polymerization method is selected as a polymerization method of the methacrylic resin (A), from the viewpoint of preventing the coloring of the methacrylic resin (A), the peroxide polymerization start It is preferable to polymerize using an agent.
Examples of the peroxide-based polymerization initiator include, but are not limited to, lauroyl peroxide, decanoyl peroxide, and t-butylperoxy-2-ethylhexanoate. Peroxide is more preferred.
When the methacrylic resin (A) is polymerized by solution polymerization at a high temperature of 90 ° C. or higher, a peroxide having a 10-hour half-life temperature of 80 ° C. or higher and being soluble in the organic solvent used It is preferable to use an azobis initiator or the like as a polymerization initiator.
Examples of the peroxide and azobis initiator include, but are not limited to, for example, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, cyclohexane peroxide, 2 Examples include 5-dimethyl-2,5-di (benzoylperoxy) hexane, 1,1-azobis (1-cyclohexanecarbonitrile), 2- (carbamoylazo) isobutyronitrile and the like.

When manufacturing a methacrylic resin (A), you may control the molecular weight of methacrylic resin (A) in the range which does not impair the objective of this invention. The method for controlling the molecular weight of the methacrylic resin (A) is not limited to the following. For example, a chain transfer agent such as alkylmercaptans, dimethylacetamide, dimethylformamide, triethylamine, dithiocarbamates, triphenyl There is a method of controlling molecular weight by using an iniferter such as methylazobenzene or tetraphenylethane derivative. Moreover, it is also possible to adjust molecular weight by adjusting the addition amount of these.
As the chain transfer agent, alkyl mercaptans are preferable from the viewpoint of handleability and stability, and the alkyl mercaptans 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 dithio glycolate, trimethylol propane tris (thioglycoat), pentaerythritol tetrakis (thio glycolate) Etc.).
These can be added as appropriate according to the molecular weight of the target methacrylic resin, but generally, it is 0 based on 100 parts by weight of the total amount of all monomers used in polymerization of the methacrylic resin. It is used in the range of .001 parts by mass to 5 parts by mass.
Further, as other molecular weight control methods, methods of changing polymerization methods, methods of adjusting polymerization initiator, amount of chain transfer agent, iniferter, etc. described above, methods of changing various polymerization conditions such as polymerization temperature, etc. may be mentioned. .
These molecular weight control methods may use only one type of method, or two or more types of methods may be used in combination.

<Ultraviolet absorber (B)>
The methacrylic resin composition of the present embodiment contains a UV absorber (B).
Examples of the ultraviolet absorber (B) include, but are not limited to, benzotriazole compounds, benzotriazine compounds, benzoate compounds, benzophenone compounds, oxybenzophenone compounds, phenol compounds, and oxazole compounds. Compounds, malonic acid ester compounds, cyanoacrylate compounds, lactone compounds, salicylic acid ester compounds, benzoxazinone compounds and the like can be mentioned, with preference given to benzotriazole compounds and benzotriazine compounds. Examples of product names include Tinuvin P manufactured by BASF, Tinuvin 234, Tinuvin 326, Tinuvin 329, Tinuvin 213, Tinuvin 571 and the like.
One of these may be used alone, or two or more may be used in combination.

The melting point (Tm) of the ultraviolet absorber (B) is preferably 90 ° C. or more, more preferably 100 ° C. or more, still more preferably 130 ° C. or more, from the viewpoint of obtaining excellent molding processability and bleeding out. Even more preferably, the temperature is 160 ° C. or higher.
Here, “excellent molding processability” means that adhesion of the ultraviolet absorber (B) to the surface of the mold is small, for example, at the time of injection molding.

<Content of UV absorber (B)>
The content of the ultraviolet absorber (B) is at least 0.01 parts by mass with respect to 100 parts by mass of the methacrylic resin (A) in order to effectively absorb ultraviolet rays and prevent the denaturation of the infrared absorber (E). Is more preferably 0.02 parts by mass or more, still more preferably 0.03 parts by mass or more, still more preferably 0.04 parts by mass or more, and particularly preferably 0.05 parts by mass or more . Moreover, in order to suppress the bleed out at the time of shaping | molding, it is preferable that content of a ultraviolet absorber (B) is 0.5 mass part or less with respect to 100 mass parts of methacrylic resin (A), and more preferable. Is 0.3 parts by mass or less, more preferably 0.2 parts by mass or less, and still more preferably 0.15 parts by mass or less.

<Phosphate stabilizer (C)>
The methacrylic resin composition of the present embodiment contains a phosphoric acid based stabilizer (C).
As a phosphoric acid stabilizer (C), although it is not limited to the following, For example, CAS No. 1 31570-04-4, 3806-34-6, 26741-53-7, 119345-01-6, 203255-81-6, 145650-60-8, 52664-24-1, 80693-00-1, 126050- 54-2, 80410-33-9, 154862-43-8, and the like.
The phosphate stabilizer (C) of this embodiment has two or more aromatic rings directly bonded to an oxygen atom, and two or more aromatic rings directly bonded to an oxygen atom are It is preferred to use one which is bonded directly or via-(CH ₂ ) _n- (n is an integer of 1 to 4, preferably 1 to ₂ ). When such a phosphoric acid stabilizer (C) is used in combination with the hindered phenol stabilizer (D), the effect of suppressing the oxidative deterioration of the infrared absorber (E) becomes remarkable, and the hindered stabilizer is also hindered. Oxidative degradation of the phenolic stabilizer (D) can be suppressed, and even if exposed to high temperature environment or high temperature and humidity environment for a long time, modification of the infrared absorber (E) is suppressed and infrared absorption ability is maintained. I can do it.
The aromatic ring includes an aromatic hydrocarbon group having 3 to 16 carbon atoms, preferably 3 to 6 carbon atoms, or a heteroaromatic group, and specific examples thereof include a phenyl group, a naphthyl group, a pyrenyl group and a phenanthrenyl group. Groups, aromatic hydrocarbon groups such as anthracenyl group; and heteroaromatic groups such as imidazole group, pyrazole group, oxazole group, thiazole group, pyrazine group, pyridyl group, quinoline group, and isoquinoline group.
As a phosphoric acid stabilizer (C), it has two or more aromatic rings directly bonded to an oxygen atom, and two or more aromatic rings directly bonded to an oxygen atom are directly or Specific product names of those bonded via CH ₂ ) _n- (n is an integer of 1 to 4) are, for example, Adekastab HP-10 manufactured by Adeka, Sumilyizer GP manufactured by Sumitomo Chemical, Irgafos 12 manufactured by BASF, Sanko HCA etc. are mentioned.

  The melting point (Tm) of the phosphoric acid stabilizer (C) is preferably 90 ° C. or more, more preferably 93 ° C. or more, still more preferably 96 ° C. or more, and still more preferably, from the viewpoint of achieving good dispersibility. Is 100 ° C. or higher.

<Content of phosphoric acid stabilizer (C)>
The content of the phosphoric acid stabilizer (C) is 0.03 parts by mass or more with respect to 100 parts by mass of the methacrylic resin (A) in order to effectively prevent the modification of the infrared absorber (E) Is more preferably 0.05 parts by mass or more, still more preferably 0.06 parts by mass or more, and still more preferably 0.08 parts by mass or more. Further, in order to prevent mold contamination due to bleed out, the content of the phosphoric acid based stabilizer (C) is preferably 0.5 parts by mass or less with respect to 100 parts by mass of the methacrylic resin (A). It is more preferably 0.45 parts by mass or less, still more preferably 0.4 parts by mass or less, and still more preferably 0.35 parts by mass or less.

<Hindered phenolic stabilizer (D)>
The methacrylic resin composition of the present embodiment contains a hindered phenol stabilizer (D).
The hindered phenol-based stabilizer (D) is not limited to the following. 96-69-5, 6683-19, 2082-79-3, 90498-90-1, 79-74-3, 1879-09-0, 85-60-9, 119-47-1, 36443- 68-2, 68610-51-5, 61167-58-6, 123968-25-2, 991-84-4, 40601-76-1, 27676-62-6, 1709-70-2, 32687-78- 8, 41484-35-9, 23128-74-7, 35074-77-2, 35958-30-6 and the like.
The hindered phenol-based stabilizer (D) has a ring structure (5-membered ring, 6-membered ring, etc.) containing 1 to 3 and preferably 2 to 3 heteroatoms such as oxygen atom or nitrogen atom in the molecule It is preferable to use one having at least one). When such a hindered phenol-based stabilizer (D) is used in combination with a phosphoric acid-based stabilizer (C), the effect of suppressing the oxidative deterioration of the phosphoric acid-based stabilizer (C) becomes remarkable, and the high temperature environment Even when exposed to a lower temperature or a high temperature and humidity environment for a long time, denaturation of the infrared absorber (E) can be suppressed, and the infrared absorbing ability can be maintained. As a specific product name of the hindered phenol type stabilizer (D) having at least one ring structure containing a heteroatom such as oxygen atom or nitrogen atom in the molecule, for example, Sumyzer GA-80 manufactured by Sumitomo Chemical Co., Ltd. Adeka Stub AO-80 manufactured by Adeka, Adeka Stub AO-20 manufactured by Adeka, Irganox 565 manufactured by BASF, SONGNOX 1790 manufactured by SONGON, SONGNOX 3114 manufactured by SONGON, and the like.

  The melting point (Tm) of the hindered phenol stabilizer (D) is preferably 90 ° C. or more, more preferably 93 ° C. or more, still more preferably 96 ° C. or more, from the viewpoint of achieving good dispersibility. Preferably it is 100 degreeC or more.

<Content of hindered phenol stabilizer (D)>
The content of the hindered phenol stabilizer (D) is a methacrylic resin (A) 100 in order to effectively suppress the deterioration of the phosphoric acid stabilizer (C) and the deterioration of the infrared absorber (E). The amount is preferably 0.03 parts by mass or more, more preferably 0.05 parts by mass or more, still more preferably 0.06 parts by mass or more, and still more preferably 0.08 parts by mass or more with respect to the mass parts. Moreover, in order to suppress coloring of a resin composition, it is preferable that it is 0.5 mass part or less with respect to 100 mass parts of methacrylic resin (A), More preferably, it is 0.4 mass part or less, More preferably, 0 0.3 parts by mass or less, still more preferably 0.2 parts by mass or less.

Melting point of UV absorber (B), phosphoric acid stabilizer (C), and hindered phenol stabilizer (D)>
The melting point (Tm) of the ultraviolet absorber (B), the phosphoric acid stabilizer (C), and the hindered phenol stabilizer (D) is from the viewpoint of suppressing the modification of the infrared absorber (E) in the present embodiment. It is preferable that all are 90 degreeC or more. When the melting point of the ultraviolet light absorber (B), the phosphoric acid stabilizer (C), and the hindered phenol stabilizer (D) is 90 ° C. or more, the methacrylic resin is produced by heat melting in the production of the methacrylic resin composition When the other components are dispersed in (A), the viscosity is not lowered more than necessary, and good dispersibility can be achieved, and the deterioration of the infrared absorber (E) can be more effectively suppressed. Because it can be From this viewpoint, the melting point of the ultraviolet light absorber (B), the phosphoric acid stabilizer (C), and the hindered phenol stabilizer (D) is more preferably 93 ° C. or higher, still more preferably 96 ° C. or higher, and 100 ° C. The above is even more preferable.

<Infrared absorber (E)>
The methacrylic resin composition of the present embodiment contains an infrared absorber (E).
The infrared absorber (E) may be a compound having an absorption maximum wavelength in the infrared region while suppressing a decrease in visible light transmittance, and it is preferable to have maximum absorption in the range of 700 to 2000 nm, and 1000 to 1700 nm It is more preferable to have it in the range.
The infrared absorber (E) is not limited to the following, but specifically, inorganic tungsten oxide, lanthanum boride, complex tin oxide, inorganic compounds such as titanium oxide, perylene dye, cyanine dye, Organic compounds such as quaterylene dyes, phthalocyanine dyes, naphthalocyanine compounds, nickel dithiolene compounds, squalium dyes, quinone compounds, diimmonium compounds and azo compounds can be mentioned.
Phthalocyanine compounds, tungsten oxide compounds, lanthanum boride and diimmonium dyes are more preferable from the viewpoint of weatherability, and tungsten oxide compounds and lanthanum boride are more preferable. By employing a tungsten oxide-based compound (for example, cesium-doped tungsten oxide) or lanthanum boride (for example, lanthanum hexaboride), the shielding ratio at around 800 nm can be improved. Furthermore, by employing a tungsten oxide compound or lanthanum boride, the finally obtained methacrylic resin composition can be hardened, thermal movement can be appropriately suppressed, oxygen can be blocked, and high light resistance And heat resistance can be achieved. This effect is significantly and effectively exhibited when using tungsten oxide into which cesium is introduced.
When inorganic particles are used, the diameter (Sheller diameter) of particles calculated by the Scheller method in order to effectively absorb infrared rays is preferably 10 nm or more. In addition, from the viewpoint of securing the transparency of the methacrylic resin composition, the diameter of the particles calculated by the Scherrer method is preferably 100 nm or less. The particle size is more preferably 15 to 80 nm, further preferably 20 to 60 nm, still more preferably 30 to 50 nm, and still more preferably 35 to 45 nm.

When inorganic particles are selected as the infrared absorber (E), a dispersant may be coated on the surface of the inorganic particles in order to improve the compatibility with the methacrylic resin (A) and ensure good dispersibility. preferable. Preferred as dispersants are polyacrylates, polyethers and polyester-based polymers, in which case polyacrylates such as polymethyl methacrylate and polyesters are particularly preferred as dispersants which are stable even at high temperatures. Mixtures of these polymers or acrylate copolymers can also be used.
Dispersants suitable for this embodiment are commercially available. In particular, dispersants based on polyacrylates are suitable. Such suitable dispersants are available, for example, from Ciba Specialty Chemicals under the tradenames EFKA®, EFKA® 4500, and EFKA® 4530. Polyester-containing dispersants are likewise suitable. They are available, for example, from Avecia under the trade names Solsperse®, Solsperse® 20000, 24000 Sc, 26000, 27000. In addition, polyether-containing dispersants are also known and are available, for example, under the trade names Disparlon® DA234 and DA325 manufactured by Kusumoto Chemical. Systems based on polyurethanes are also suitable. Polyurethane based systems are available from Ciba Specialty Chemicals under the trade names EFKA® 4046, EFKA® 4047. Texaphor® P60 and P63 are the corresponding trade names of Cognis.

<Content of infrared absorber (E)>
The content of the infrared absorber (E) is at least 0.002 parts by mass with respect to 100 parts by mass of the methacrylic resin (A) when an infrared absorber of an organic compound is used to effectively absorb infrared rays. Is preferred. The amount is more preferably 0.003 parts by mass or more, still more preferably 0.005 parts by mass or more, and still more preferably 0.008 parts by mass or more. Also, from the viewpoint of maintaining the transparency and high appearance of the methacrylic resin composition, the content of the infrared absorber (E) is 100 mass of the methacrylic resin (A) when using the infrared absorber (E) of an organic compound. It is preferable that it is 0.5 mass part or less with respect to part, 0.1 mass part or less is more preferable, 0.07 mass part or less is more preferable, 0.05 mass part or less is still more preferable, 0.02 Particularly preferred are parts by weight or less.

When using an infrared absorber of an inorganic compound as the infrared absorber (E), in order to effectively absorb infrared rays, it is 0.002 parts by mass or more with respect to 100 parts by mass of the methacrylic resin (A) The content is preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, still more preferably 0.012 parts by mass or more, and particularly preferably 0.015 parts by mass or more. Further, from the viewpoint of maintaining the transparency and high appearance of the acrylic resin, the content in the case of using the infrared absorber (E) of the inorganic compound is 0.1 parts by mass or less with respect to 100 parts by mass of the methacrylic resin (A). Is preferable, 0.07 parts by mass or less is more preferable, 0.05 parts by mass or less is more preferable, and 0.035 parts by mass or less is still more preferable.
If the content of the infrared absorber (E) is within the above-mentioned range, the methacrylic resin composition of the present embodiment may be appropriately selected in accordance with the infrared absorbing ability required for the application.
In addition, content of the infrared rays absorber (E) in this embodiment is content in the active ingredient except surface treatment agents, such as a dispersing agent.

<Other components that can be mixed with the methacrylic resin composition>
<< Other resin >>
In the methacrylic resin composition of the present embodiment, other conventionally known resins can be mixed as long as the effects of the present invention are not impaired.
The other resins are not particularly limited, and known curable resins and thermoplastic resins are preferably used.
The thermoplastic resin is not limited to the following. For example, polypropylene resin, polyethylene resin, polystyrene resin, syndiotactic polystyrene resin, ABS resin, methacrylic resin, AS resin, BAAS -Based resin, MBS resin, AAS resin, biodegradable resin, alloy of polycarbonate-ABS resin, polybutylene terephthalate, polyethylene terephthalate, polypropylene terephthalate, polytrimethylene terephthalate, polyalkylene arylate resin such as polyethylene naphthalate, polyamide resin And polyphenylene ether resins, polyphenylene sulfide resins, and phenol resins.
In particular, AS resin and BAAS resin are preferable in order to improve flowability, and ABS resin and MBS resin are preferable in order to improve impact resistance, and polyester resin is preferable in order to improve chemical resistance.
In addition, polyphenylene ether resins, polyphenylene sulfide resins, phenol resins and the like can obtain the effect of improving the flame retardancy.
The curable resin is not limited to the following. For example, unsaturated polyester resin, vinyl ester resin, diallyl phthalate resin, epoxy resin, cyanate resin, xylene resin, triazine resin, urea resin, melamine resin And benzoguanamine resin, urethane resin, oxetane resin, ketone resin, alkyd resin, furan resin, styrylpyridine resin, silicone resin, synthetic rubber and the like.
One of these resins may be used alone, or two or more resins may be used in combination.

"Additive"
Various additives may be mixed with the methacrylic resin composition of the present embodiment as long as the effects of the present invention are not impaired in order to impart predetermined various characteristics such as rigidity and dimensional stability.
Examples of the additive include, but are not limited to, plasticizers such as phthalic acid esters, fatty acid esters, trimellitic esters, phosphoric esters, polyesters, etc .; higher fatty acids, higher fatty acid esters , Release agents such as mono-, di-, or triglycerides of higher fatty acids; Antistatic agents such as polyethers, polyetheresters, polyetheresteramides, alkyl sulfonates, alkylbenzene sulfonates, phosphines Agents, stabilizers such as light stabilizers; flame retardants, flame retardant aids, curing agents, curing accelerators, conductivity imparting agents, stress relaxation agents, crystallization accelerators, dyes, hydrolysis inhibitors, lubricants, resistance Impact modifiers, slide improvers, compatibilizers, nucleating agents, tougheners, reinforcements, flow control agents, sensitizers, pigments for coloring, rubbery polymers, thickeners, anti-settling agents, Les agents, fillers, antifoaming agents, coupling agents, rust inhibitors, antibacterial and antifungal, antifouling agent, a conductive polymer, carbon black and the like.

The content of the other resins and additives described above in the methacrylic resin composition for obtaining the molded article of the methacrylic resin composition of the present embodiment maintains the transparency of the methacrylic resin composition, and bleeds out. 0 to 40% by mass, preferably 0.01 to 30% by mass, and more preferably 0.02 to 25% by mass with respect to 100% by mass of the methacrylic resin composition in order to prevent molding defects such as .
By containing in the said numerical range, the function of each material can be exhibited.

<Transmittance of 1000-nm wavelength of methacrylic resin composition>
A large amount of light is contained in sunlight at a wavelength of 1000 nm, and it is important to efficiently absorb light at a wavelength of 1000 nm. If the transmittance of the methacrylic resin composition at a wavelength of 1000 nm is 60% or less within the above range of the content of the infrared absorber (E), the methacrylic resin composition has a good infrared absorbing ability I can say that. The transmittance of the methacrylic resin composition at a wavelength of 1000 nm is preferably 50% or less, more preferably 40% or less, and still more preferably 38% or less.
In the present disclosure, the transmittance at a wavelength of 1000 nm is a value measured by the procedure described in the section of “Example” described later.

<Method of Producing Methacrylic Resin Composition>
The methacrylic resin composition comprises a methacrylic resin (A), an ultraviolet light absorber (B), a phosphoric acid based stabilizer (C), a hindered phenol based stabilizer (D), and an infrared light absorber (E). In accordance with the above, it is obtained by mixing and kneading the various additives described above and other resins.
For example, it can manufacture by knead | mixing using kneading machines, such as an extruder, a heating roll, a kneader, a roller mixer, and a Banbury mixer.
In particular, kneading using an extruder is preferable from the viewpoint of productivity.
The kneading temperature is preferably 170 ° C. or more, more preferably 180 ° C. or more, and still more preferably 200 ° C. or more from the viewpoint of productivity. The temperature is preferably 290 ° C. or less, more preferably 280 ° C. or less, and still more preferably 270 ° C. or less from the viewpoint of preventing deterioration of the methacrylic resin (A) and the infrared absorber (E) and evaporation of various additives.

<Molded body>
The molded article of the present embodiment is characterized by containing the methacrylic resin composition of the present embodiment described above.

<Method of manufacturing molded body>
The molded body of the present embodiment can be manufactured by a known molding method. Examples of known molding methods include, but are not limited to, injection molding, extrusion molding, blow (hollow) molding, vacuum molding, compression molding, calendar molding, inflation molding, and the like. In particular, molding by injection molding is preferable from the viewpoint of productivity.
The molding temperature is preferably 170 ° C. or more, more preferably 190 ° C. or more, and still more preferably 200 ° C. or more from the viewpoint of productivity. The temperature is preferably 290 ° C. or less, more preferably 280 ° C. or less, still more preferably 270 ° C. or less, from the viewpoint of deterioration of the methacrylic resin (A) or the infrared absorber (E) and volatilization of various additives.

<Use of molded body>
The molded article containing the methacrylic resin composition of the present embodiment is excellent in heat blocking property, antifogging property, infrared absorbing ability, long-term stability against outdoor environment where ultraviolet rays are applied, long-term heat stability, long-term moist heat Since a resin molded product excellent in stability can be obtained, it can be suitably used as a member for construction, a member for vehicles, a member for electric and electronic parts, a member for illumination and the like. Specifically, the application of the molded body of the present embodiment is, for example, a roofing material used for a building, an automobile, a train or a bus, a protective material used for a light, a signboard, and a meter, a member for a vehicle lamp It is a member for lamps of ships, a protective cover for batteries, etc.
It is particularly preferable to be used as a member for a vehicle lamp, since it becomes possible to develop antifogging properties and to maintain antifogging properties for a long time.

  Hereinafter, the present embodiment will be specifically described by way of examples, but the present embodiment is not limited to the examples described later.

Raw materials used in Examples and Comparative Examples
Raw Material of Methacrylic Resin (A)
The raw materials of the methacrylic resin (A) used for manufacture of a methacrylic resin composition are as follows.
-Methyl methacrylate (MMA): manufactured by Asahi Kasei Chemicals (in which 2.5 ppm of 2,4-dimethyl-6-t-butylphenol manufactured by Chugai Foreign Trade Co., Ltd. is added as a polymerization inhibitor)
・ Methyl acrylate (MA): manufactured by Mitsubishi Chemical (as a polymerization inhibitor, 14 ppm of 4-methoxyphenol (4-methoxyphenol) is added)
· Ethyl acrylate (EA): manufactured by Mitsubishi Chemical · n-octylmercaptan: manufactured by Arkema · lauroyl peroxide: manufactured by NOF Corp. · calcium phosphate tribasic: manufactured by Nippon Chemical Industries, used as a suspending agent · calcium carbonate: manufactured by Shiraishi Kogyo, Used as a suspending agent-Sodium lauryl sulfate: manufactured by Wako Pure Chemical Industries, used as a suspending aid

<Ultraviolet absorber (B)>
(B-1) Tinuvin P: manufactured by BASF Melting point 128 ° C.
(B-2) Tinuvin 234: made by BASF Melting point 137 ° C.

<Phosphate stabilizer (C)>
(C-1) Adeka Stub 2112: Made of Adeka Melting point 180 ° C.
(C-2) Adekastab HP-10: Made of Adeka Melting point 146 ° C.
(C-3) Sumilyzer GP: made by Sumitomo Chemical Melting point 115 ° C.
(C-4) Adekastab PEP-8: Made of Adeka Melting point 50 ° C.

<Hindered phenolic stabilizer (D)>
(D-1) Adekastab AO-80: Made by Adeka 110 ° C.
(D-2) Irganox 1010: manufactured by BASF Melting point 110 ° C.
(D-3) Irganox 565: made by BASF Melting point 91 ° C.

<Infrared absorber (E)>
(E-1) YMDS 874: Cesium-doped tungsten oxide manufactured by Sumitomo Metal Mining Co., Ltd. (effective component ratio 23 mass%, Scherrer diameter 32 nm)
(E-2) YMDS 874 BT: cesium-doped tungsten oxide manufactured by Sumitomo Metal Mining Co., Ltd. (effective component ratio 23 mass%, Scherrer diameter 36 nm)
(E-3) FDN-006: Yamada Chemical Industries Phthalocyanine-based dye (E-4) KHDS 06: Sumitomo Metal Mining Co., Ltd. Lanthanum hexaboride (active ingredient ratio 21.5 mass%, Scherrer diameter 86 nm)

<Other additives>
(Additive 1) Tri-o-tolyl phosphine: Tokyo Chemical Industry Co., Ltd. Melting point 124 ° C.
(Additive 2) Triphenylphosphine: manufactured by Tokyo Chemical Industry, melting point 81 ° C.

[Measurement, evaluation method]
<I. Molecular weight measurement of methacrylic resin (A)>
The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) (Mn is a number average molecular weight) of the methacrylic resin (A) were measured using the following apparatus and conditions.
-Measuring device: gel permeation chromatography (HLC-8320 GPC) manufactured by Tosoh Corporation
·Measurement condition:
Column: One TSKguard column SuperH-H, two TSKgel SuperHM-M, and one TSKgel SuperH2500 were sequentially connected in series and used. In this column, high molecular weight elutes quickly, and low molecular weight elutes slowly.
Detector: RI (differential refraction) detector Detection sensitivity: 3.0 mV / min
Column temperature: 40 ° C
Sample: 0.02 g of methacrylic resin in tetrahydrofuran 20 mL solution Injection amount: 10 μL
Developing solvent: tetrahydrofuran, flow rate: 0.6 mL / min, 0.1 g / L of 2,6-di-t-butyl-4-methylphenol (BHT) was added as an internal standard.
As a standard sample for calibration curve, the following 10 polymethyl methacrylates (manufactured by Polymer Laboratories; PMMA Calibration Kit M-M-10) having known monodispersed peak molecular weights and different molecular weights were used.
In addition, since polymethyl methacrylate of the standard sample used for the standard sample for calibration curve is a thing of a single peak, respectively, the peak corresponding to each was described with the weight peak molecular weight Mp. This point was distinguished from the peak top molecular weight calculated when there are a plurality of peaks for one sample.
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 document 10 850
The RI detection intensity with respect to the elution time of the methacrylic resin (A) was measured under the above conditions.
The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) of the methacrylic resin (A) were determined based on the area area in the GPC elution curve and the calibration curve of the third approximation formula.

<II. Analysis of Methacrylic resin (A) structural unit>
^The structural unit was identified by ¹ H-NMR measurement, and its abundance (mass%) was calculated.
The measurement conditions of ¹ H-NMR measurement are as follows.
Device: JEOL-ECA 500
Solvent: CDCl ₃ -d ₁ (deuterated chloroform)
Sample: 15 mg of component (A) was dissolved in 0.75 mL of CDCl ₃ -d _{1 to} prepare a measurement sample.

<III. Infrared absorption ability>
The transmittance (%) at a wavelength of 1000 nm of flat plate samples prepared in Examples and Comparative Examples described later was measured using UV-3100PC manufactured by Shimadzu Corporation. If the transmittance at a wavelength of 1000 nm is 60% or less, it can be said that it has good infrared absorptivity.

<IV. Long-term heat stability>
The change in transmittance (%) at a wavelength of 1000 nm before and after standing for 1000 hours at 100 ° C. in a circulating hot air oven for flat plate samples prepared in Examples and Comparative Examples described later It measured using 3100PC. ◎ (excellent) if the change in transmittance at a wavelength of 1000 nm is 15% or less, ((good) if it is more than 15% and 18% or less, Δ (acceptable) if it is more than 18% and 21% If it is, it was considered as x (impossible). If the change in transmittance is within 21%, it can be said that it has long-term heat stability sufficient for practical use.

<V. Long-term moist heat stability>
Transmittances at a wavelength of 1000 nm before and after standing for 1000 hours in an environment at a temperature of 80 ° C. and a humidity of 95% using flat plates prepared in Examples and Comparative Examples to be described later using ESPEC Co., Ltd. The change of (%) was measured using Shimadzu UV-3100PC. ◎ (excellent) if the change in transmittance at a wavelength of 1000 nm is within 9.0%, 〇 (good) if it is over 9.0% and within 10.0%, and within 10.0% and 11.0% If there is, it is regarded as △ (Possible), and if it is more than 11.0%, it is regarded as x (Poor). If the change in the transmittance is less than 11.0%, it can be said that it has long-term moist heat stability sufficient for practical use.

<VI. Long-term stability to outdoor environments exposed to ultraviolet light>
For flat plate samples prepared in Examples and Comparative Examples to be described later, irradiation in a Sunshine Weather Meter (SWOM) made by Suga Test Instruments for 4 hours at 63 ° C., and wetting (condensation) in 40 ° C. for 4 hours continuously for 1000 hours Changes in the total light transmittance (%) of the tested flat plate samples were measured using Nippon Denshoku 1001DP. Moreover, the change of the transmittance | permeability (%) in wavelength 1000nm was measured using Shimadzu Corporation UV-3100PC.
変 化 (excellent) if the change in total light transmittance is within 2.0%, ((good) if it is over 2.0% and 2.5% or less, Δ if it is over 2.5% and 3.5% Yes), more than 3.5% was considered as x (impossible).
In addition, if the change in transmittance at a wavelength of 1000 nm is 6% or less, ((excellent), if 6% or more and 7% or less, ((good), if 7% or more and 8% or less For example.
If the change of the total light transmittance is within 3.5% and the change of the transmittance at a wavelength of 1000 nm is within 8%, it can be said that it has practically sufficient long-term stability against the outdoor environment to which ultraviolet rays are applied.

[Methacryl-based resin composition]
The methacrylic resin (A) used as a component of the methacrylic resin composition in Examples and Comparative Examples described later will be described below.

(Methacrylic resin (A))
As methacrylic resin (A), the methacrylic resin of (A-1)-(A-3) manufactured by following manufacture example A1-A3 was used.

<Production Example A1 (Production of Methacrylic Resin (A-1))>
In a container equipped with a stirrer, 2 kg of ion exchange water, 65 g of tribasic calcium phosphate, 39 g of calcium carbonate: 39 g, and 0.39 g of sodium lauryl sulfate: 0.39 g were obtained to obtain a liquid mixture (a).
Next, 26 kg of ion exchanged water is charged into a 60 L reactor and the temperature is raised to 80 ° C., and the mixed solution (a), methyl methacrylate: 21.2 kg, methyl acrylate: 0.43 kg, lauroyl peroxide: 27 g and 62 g of n-octyl mercaptan were charged.
Thereafter, suspension polymerization was carried out while maintaining about 80 ° C., and after observing the exothermic peak, the temperature was raised to 92 ° C. at a rate of 1 ° C./min, and aging was carried out for 60 minutes to substantially complete the polymerization reaction.
Next, in order to cool to 50 ° C. to dissolve the suspending agent, 20 mass% sulfuric acid was added, and then the polymerization reaction solution was sieved through a 1.68 mm mesh screen to remove aggregates, and the resulting beaded polymer was obtained Washing, dehydration and drying were carried out to obtain polymer fine particles [methacrylic resin (A-1)].
The weight average molecular weight of the obtained resin was 10.20, and the molecular weight distribution (Mw / Mn) was 1.85. Moreover, the structural unit was MMA / MA = 98/2 mass%.

<Production Example A2 (Production of Methacrylic Resin (A-2))>
In a container equipped with a stirrer, 2 kg of ion exchange water, 65 g of tribasic calcium phosphate, 39 g of calcium carbonate: 39 g, and 0.39 g of sodium lauryl sulfate: 0.39 g were obtained to obtain a mixed solution (b).
Next, 26 kg of ion exchanged water is charged into a 60 L reactor, and the temperature is raised to 80 ° C., and the mixed solution (b), methyl methacrylate: 20.5 kg, ethyl acrylate: 1.32 kg, lauroyl peroxide: 33 g And n-octyl mercaptan: 27.5 g was charged.
Thereafter, suspension polymerization was performed while maintaining about 80 ° C., and after observing an exothermic peak, the temperature was raised to 92 ° C. at a rate of 1 ° C./min.
Thereafter, it was aged for 60 minutes to substantially complete the polymerization reaction.
Next, in order to cool to 50 ° C. to dissolve the suspending agent, 20 mass% sulfuric acid was added, and then the polymerization reaction solution was sieved through a 1.68 mm mesh screen to remove aggregates, and the resulting beaded polymer was obtained Washing, dehydration and drying were carried out to obtain polymer fine particles [methacrylic resin (A-2)].
The weight average molecular weight of the obtained resin was 189,000, and the molecular weight distribution (Mw / Mn) was 1.85. Moreover, the structural unit was MMA / EA = 94/6 mass%.

<Production Example A3 (Production of Methacrylic Resin (A-3))>
In a container equipped with a stirrer, 2 kg of ion exchange water, 65 g of tribasic calcium phosphate, 39 g of calcium carbonate, and 0.39 g of sodium lauryl sulfate were charged to obtain a mixed solution (c).
Next, 26 kg of ion exchanged water is charged into a 60 L reactor and the temperature is raised to 80 ° C., and the mixed solution (c), methyl methacrylate: 21.2 kg, methyl acrylate: 0.43 kg, lauroyl peroxide: 27 g and 88 g of n-octyl mercaptan were charged.
Thereafter, suspension polymerization was carried out while maintaining about 80 ° C., and after observing the exothermic peak, the temperature was raised to 92 ° C. at a rate of 1 ° C./min, and aging was carried out for 60 minutes to substantially complete the polymerization reaction.
Next, in order to cool to 50 ° C. to dissolve the suspending agent, 20 mass% sulfuric acid was added, and then the polymerization reaction solution was sieved through a 1.68 mm mesh screen to remove aggregates, and the resulting beaded polymer was obtained Washing, dehydration and drying were carried out to obtain polymer fine particles [methacrylic resin (A-3)].
The weight average molecular weight of the obtained resin was 73,000, and the molecular weight distribution (Mw / Mn) was 1.85. Moreover, the structural unit was MMA / MA = 98/2 mass%.

[Examples 1 to 18] [Comparative Examples 1 to 5]
Methacrylic resin (A), UV absorber (B), phosphoric acid stabilizer (C), hindered phenol stabilizer (D), infrared absorber (E) so as to achieve the blending ratio described in Table 1 After weighing each of the other additives, it was introduced into a Henschel mixer, and they were mixed by stirring. After mixing by sufficient stirring, the mixed raw materials are charged into a φ26 mm twin-screw extruder, melt-kneaded (compounded) to form a strand, the strand is cooled in a water bath, and cut by a pelletizer to obtain pellets I got In compounding, a vacuum line was connected to the vent part of the extruder, and volatile components such as water and monomer components were removed under the condition of -0.06 MPa. Thus, a methacrylic resin composition was obtained. In addition, the resin temperature of the resin composition at the time of compounding was 250-270 degreeC.
The numerical values in Table 1 represent the number of parts (parts by mass) when the mass of the methacrylic resin (A) as the base material is 100 parts by mass.

[Plate sample]
(injection molding)
Pellets of the obtained methacrylic resin composition were charged into an injection molding machine, and formed into a flat plate (100 mm × 100 mm × 2 mm) to obtain a flat plate sample for evaluation. The mold used was one whose mold surface (the inner surface of the mold cavity) was polished with a polishing number 8000. Then, the surface of the molded product to which the mold surface of the side polished by the polishing number 8000 is transferred is used as the test surface of this flat plate sample.
In addition, the molding conditions of this flat plate sample for evaluation were set as follows.
Resin temperature: 220 ° C to 250 ° C
Mold temperature: 70 ° C
In addition, it is important to keep the temperature of the mold at the time of injection molding higher in order to enhance the transferability of the surface of the mold polished with a polishing number 8000. However, since the glass transition temperature of the methacrylic resin (A) is around 110 ° C., even if it is too high, the cooling time will be too long, which is not practical. The temperature range which makes them good is 60 ° C. or more and 100 ° C. or less, more preferably 70 ° C. or more and 90 ° C. or less, still more preferably 70 ° C. or more and 85 ° C. or less.

Good infrared absorptivity was able to be achieved in Examples 1 to 18 and Comparative Examples 1 to 5. However, in Comparative Example 1, although the long-term outdoor environmental stability was good, the long-term heat stability and the long-term moist heat stability were not good because the hindered phenol stabilizer (D) was not added. . In Comparative Example 2, since the phosphoric acid-based stabilizer (C) was not added, none of the long-term heat stability, the long-term moist heat stability, and the long-term outdoor environment stability was good. In Comparative Example 3, although the long-term heat resistance stability was good, the ultraviolet absorber (B), the hindered phenol stabilizer (D), and the phosphoric acid stabilizer (C) were not added, so the long-term stability was long. Humid heat stability, long-term outdoor environmental stability was not good. In Comparative Example 4, although the long-term outdoor environmental stability was good, the hindered phenol-based stabilizer (D) and the phosphoric acid-based stabilizer (C) were not added, so the long-term heat stability and long-term moist heat were obtained. The stability was not good. In Comparative Example 5, although it had long-term outdoor environmental stability sufficient for practical use, the long-term heat resistance stability and long-term moist heat stability were not good because the hindered phenol stabilizer (D) was not added. The
In Example 10, although practically sufficient, long-term outdoor environmental stability was slightly inferior to Examples 1-9, 11, 12, 14-18.
In Example 13, although practically sufficient, the long-term outdoor environment stability and the long-term moist heat stability were slightly inferior to Examples 1 to 9, 11, 12, 14, and 16 to 18.
In Example 15, although it was practically sufficient, the long-term wet heat characteristics were slightly inferior to Examples 1-12, 14, and 16-18.

  According to the methacrylic resin composition of the present invention, it is possible to obtain a resin molded article having good infrared absorptivity and excellent in long-term stability, long-term heat resistance stability and long-term moist heat stability against an outdoor environment exposed to ultraviolet light. Therefore, for example, roofing materials used in buildings, automobiles, trains or buses, protective materials used in lighting and billboards, meters, members for vehicle lamps, members for lamps for ships, protective covers for batteries, etc. Has the above availability.

Claims (8)

  Methacrylic resin (A) having a weight average molecular weight Mw of 70,000 to 200,000, ultraviolet absorber (B), phosphoric acid stabilizer (C), hindered phenol stabilizer (D), and infrared absorption The methacrylic resin composition containing an agent (E). The infrared absorber (E) is tungsten oxide and / or lanthanum hexaboride,
The methacrylic resin composition according to claim 1, wherein the content of the infrared absorber (E) is 0.002 to 0.05 parts by mass with respect to 100 parts by mass of the methacrylic resin (A).   0.01 to 0.3 parts by mass of the ultraviolet absorber (B) and 0.03 to 0.5 parts by mass of the phosphoric acid stabilizer (C) relative to 100 parts by mass of the methacrylic resin (A) The methacrylic resin composition according to claim 1, wherein the hindered phenol stabilizer (D) is contained in an amount of 0.03 to 0.5 parts by mass.   The melting point of the ultraviolet absorber (B), the phosphoric acid stabilizer (C), and the hindered phenol stabilizer (D) is 90 ° C. or higher. The methacrylic resin composition as described in a statement.   The methacrylic resin composition according to any one of claims 1 to 4, wherein the hindered phenol stabilizer (D) has at least one ring structure containing an oxygen atom or a nitrogen atom in the molecule. .   The molded object characterized by including the methacrylic resin composition as described in any one of Claims 1-5.   The molded object of Claim 6 used for the member for construction, the member for electric / electronics, the member for vehicles, and the member for illumination.   The molded object of Claim 7 used for the member for vehicle lamps.