JP2013256657A - Method for producing methacrylic resin, methacrylic resin and molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing a methacrylic resin having high heat resistance, and excellent color, transparency and moist heat resistance while keeping high productivity and polymerization stability.SOLUTION: There is provided a method for producing a methacrylic resin, including a polymerization step of copolymerizing 50-99 mass% of a methacrylic ester-based monomer (A), 1-30 mass% of a maleimide-based monomer (B) and 0-20 mass% of other vinylic monomers (C) in a reaction vessel, and satisfying the following conditions (1) to (3): (1) the maleimide-based monomer (B) is solid at 25°C; (2) the maleimide-based monomer (B) in a state of being dispersed in water is fed into the reaction vessel; and (3) the maleimide-based monomer (B) has a content of ≤10 mass% of components having particle diameters of ≤0.15 mm.

Description

  The present invention relates to a method for producing a methacrylic resin, a methacrylic resin, and a molded body.

Methacrylic resins typified by polymethyl methacrylate (PMMA) are widely used in the fields of optical materials, lenses, household goods, OA equipment, lighting equipment, and vehicle members because of their high transparency.
In particular, in recent years, use in optical materials such as light guide plates and liquid crystal display films has progressed, and it has also been developed for use assuming high temperature use, and higher heat resistance and optical properties are required. .

Conventionally, as a method for improving the heat resistance of PMMA, a method of introducing a maleimide monomer into a PMMA polymerization system has been proposed (for example, see Patent Documents 1 and 2).
In general, since maleimide monomers are often solid at room temperature, when the PMMA is polymerized by bulk polymerization or suspension polymerization, the maleimide monomer is a monomer other than the maleimide monomer. The solution is often subjected to a polymerization system after being dissolved in the seed. However, since it takes a long time to dissolve the maleimide monomer in the monomer species, there is a problem that the productivity is poor.
As a method of introducing the maleimide monomer into the PMMA polymerization system without dissolving it, a method of supplying the maleimide monomer as an aqueous dispersion to the polymerization system has been proposed (for example, see Patent Document 3). ). In addition, a method is also disclosed in which a maleimide monomer is directly charged into a reaction vessel and then finely dispersed in the reaction vessel and then subjected to the reaction (see, for example, Patent Document 4).

JP 61-252211 JP-A-63-304013 JP-A-62-68805 Japanese Patent Laid-Open No. 01-153707

However, in the production methods described in Patent Documents 1 and 2, a maleimide monomer is dissolved in another monomer species to obtain a solution, and the solution is supplied to a reaction vessel so that the polymerization system contains maleimide. Since monomeric monomers are introduced, maleimide monomers are difficult to dissolve in other monomer species, especially in low-temperature environments such as in winter. There is a problem that there is room.
In addition, in the production method described in Patent Document 3, maleimide monomer is dispersed in water and continuously fed as a maleimide slurry. In order to improve dispersibility, Since the particle diameter is made as small as possible, the surface area of the particle is increased, the contact area with water is increased, the maleimide is easily hydrolyzed, and the polymerization stability is lowered due to the acidic component produced. In addition, there is a problem that desired characteristics may not be obtained. Further, since continuous feeding is performed in a slurry state for a long time, the process becomes complicated and there is a problem in productivity.
In the production method described in Patent Document 4, maleimide powder is supplied to a reaction vessel and then subjected to a reaction after finely dispersing maleimide as a solid solution at a high temperature. Since it is easy to cause decomposition, the polymerization stability may be lowered. Moreover, the color tone of the obtained resin is not taken into consideration, and a production method capable of obtaining a resin having a better color tone is desired.
In view of the above-mentioned problems of the prior art, PMMA has a high productivity and a high color tone with reduced contact time between water and maleimide monomer particles in order to suppress maleimide hydrolysis. There is a need for a polymerization method.
Therefore, in the present invention, there is provided a method for efficiently producing a methacrylic resin having high heat resistance, excellent color tone and transparency, and excellent wet heat resistance while maintaining high productivity and polymerization stability. This is the issue.

As a result of intensive studies to solve the above-described problems of the prior art, the present inventors have completed the present invention.
That is, the present invention is as follows.

[1]
Methacrylic acid ester monomer (A): 50 to 99% by mass,
Maleimide monomer (B) 1-30% by mass,
And other vinyl monomer (C): having a polymerization step of copolymerizing 0 to 20% by mass in a reaction vessel,
A method for producing a methacrylic resin that satisfies the following conditions (1) to (3).
(1) The maleimide monomer (B) is solid at 25 ° C. (2) The maleimide monomer (B) is supplied to the reaction vessel in a state dispersed in water.
(3) In the maleimide monomer (B), the content of a particle size component of 0.15 mm or less is 10% by mass or less.
[2]
The methacrylic acid according to [1], wherein the aqueous dispersion of the maleimide monomer (B) is supplied into the reaction vessel at a temperature 20 ° C. or more lower than the melting point of the maleimide monomer (B). Method for production of resin.
[3]
Polymerization monomers other than the maleimide monomer (B),
The methacrylic resin according to [1] or [2], wherein the reaction vessel is fed into the reaction vessel under a condition that the temperature is lower by 20 ° C. or more than the melting point of the maleimide monomer (B). Manufacturing method.
[4]
The methacrylic resin according to any one of [1] to [3], wherein the maleimide monomer (B) is at least one selected from the group consisting of N-phenylmaleimide and N-cyclohexylmaleimide. Production method.
[5]
The method for producing a methacrylic resin according to any one of [1] to [4], wherein the polymerization step is performed by a suspension polymerization method.
[6]
The method for producing a methacrylic resin according to any one of [1] to [5], wherein the temperature of water in which the maleimide monomer (B) is dispersed is 0 ° C. or higher and 80 ° C. or lower.
[7]
The method for producing a methacrylic resin according to any one of [1] to [6], wherein a content of a particle size component of 9.5 mm or more of the maleimide monomer (B) is 10% by mass or less. .
[8]
The method for producing a methacrylic resin according to any one of [1] to [7], wherein the maleimide monomer (B) has an average particle size of 0.2 mm or more and 9 mm or less.
[9]
In the polymerization step, the polymerization initiator is supplied to the reaction tank together with the methacrylic ester monomer (A) and the other vinyl monomer (C). ] The manufacturing method of the methacrylic resin as described in any one of.
[10]
A methacrylic resin obtained by the method for producing a methacrylic resin according to any one of [1] to [9].
[11]
The molded object containing the methacrylic resin as described in said [10].

  According to the present invention, it is possible to provide a method for efficiently producing a methacrylic resin having high heat resistance and excellent color tone, transparency, and moist heat resistance while maintaining high productivity and polymerization stability. it can.

Hereinafter, although the form for implementing this invention (henceforth "this embodiment") is demonstrated in detail, this invention is not limited to the following description, In the range of the summary Various modifications can be made.
In the following, the monomer component before polymerization is referred to as “˜monomer”, and “monomer” may be omitted. Moreover, the structural unit which comprises a polymer is called "-monomer unit."

[Method for producing methacrylic resin]
In the method for producing a methacrylic resin of this embodiment,
Methacrylic acid ester monomer (A): 50 to 99% by mass,
Maleimide monomer (B) 1-30% by mass,
And the other vinyl-type monomer (C) copolymerizable with said (A) and (B): It has a polymerization process which copolymerizes 0-20 mass% in a reaction tank,
A method for producing a methacrylic resin that satisfies the following conditions (1) to (3).
(1) The maleimide monomer (B) is solid at 25 ° C. (2) The maleimide monomer (B) is supplied to the reaction vessel in a state dispersed in water.
(3) In the maleimide monomer (B), the content of a particle size component of 0.15 mm or less is 10% by mass or less.

In the production method of the present embodiment, the methacrylic acid ester monomer (A): 50 to 99% by mass, the maleimide monomer (B): 1 to 30% by mass, and the above (A) and (B) Other monomer (C) which can superpose | polymerize: A methacrylic resin is manufactured using a monomer component by the mass ratio of 0-20 mass%.
The details of each monomer component are described below.

(Methacrylic acid ester monomer (A))
As the methacrylic acid ester monomer (A) (hereinafter referred to as component (A), sometimes referred to as (A)), a monomer represented by the following general formula (1) is preferably used.

In the general formula (1), R ₁ represents 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 may have a hydroxyl group on the carbon.

Examples of the methacrylic acid ester monomer represented by the general formula (1) include, but are not limited to, butyl methacrylate, ethyl methacrylate, methyl methacrylate, propyl methacrylate, isopropyl methacrylate, Examples include cyclohexyl methacrylate, phenyl methacrylate, methacrylic acid (2-ethylhexyl), methacrylic acid (t-butylcyclohexyl), benzyl methacrylate, methacrylic acid (2,2,2-trifluoroethyl), and the like. Methyl methacrylate is preferable from the standpoint of stability.
The said methacrylic acid ester monomer may be used individually by 1 type, and may use 2 or more types together.
The methacrylic acid ester monomer (A) is 50 from the viewpoint of the effect of imparting heat resistance by the maleimide monomer (B) described later in all the monomer components used in the method for producing a methacrylic resin of this embodiment. To 99% by mass, preferably 60 to 95% by mass, more preferably 70 to 95% by mass, still more preferably 75 to 95% by mass, and even more preferably 78 to 90% by mass. .

(Maleimide monomer (B))
From the viewpoint of imparting heat resistance to the methacrylic resin, in the present embodiment, a maleimide monomer (B) (hereinafter sometimes referred to as (B) component or (B)) is used. As the system monomer, a solid monomer at 25 ° C. is used. Preferred maleimide monomers (B) include monomers represented by the following general formula (2).

R ₃ in the general formula (2) is selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, and an aryl group having 6 to 12 carbon atoms. Which may have a substituent on a carbon atom.

Examples of the maleimide monomer (B) include, but are not limited to, maleimide, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N- (o- Chlorophenyl) maleimide, N- (m-chlorophenyl) maleimide, N- (p-chlorophenyl) maleimide and the like.
Preferable examples include N-cyclohexylmaleimide, N-phenylmaleimide, N- (o-chlorophenyl) maleimide, N- (m-chlorophenyl) maleimide, N- (p-chlorophenyl) maleimide. From the viewpoint of imparting sex, more preferred are N-cyclohexylmaleimide and N-phenylmaleimide, and more preferred is N-phenylmaleimide.
The maleimide monomer (B) described above may be used alone or in combination of two or more.

In the method for producing a methacrylic resin of this embodiment, the maleimide monomer (B) is characterized in that it is dispersed in water to prepare a dispersion, and the dispersion is supplied to the reaction vessel.
By supplying the maleimide monomer (B) to the reaction vessel as an aqueous dispersion, the production time of the methacrylic resin can be shortened while maintaining good polymerization stability. The resin is excellent in color tone stability.

The average particle size of the maleimide monomer (B) is preferably 0.2 mm or more and 9 mm or less from the viewpoint of handling workability and polymerization stability during suspension polymerization of a methacrylic resin. More preferably, it is 8 mm. More preferably, it is 0.5 mm-8 mm, More preferably, it is 1 mm-5 mm.
A method for measuring the average particle size of the maleimide monomer (B) is shown below.
For example, a sieve based on JIS-Z8801, JTS-200-45-16 (mesh opening 9.5 mm), JTS-200-45-19 (mesh opening 5.6 mm), 21 (mesh opening 4.0 mm) manufactured by Tokyo Screen , 23 (aperture 2.8 mm), 25 (aperture 2.0 mm), 32 (aperture 0.6 mm), 38 (aperture 150 μm), 61 (a saucer), and sieving tester TSK B- 1 can be used to measure the particle diameter of 50% by mass using the measured value of the average particle diameter when sieving with vibration force MAX for 10 minutes.
In the method for producing a methacrylic resin of the present embodiment, as described later, the maleimide monomer (B) has a content of a particle size component of 0.15 mm or less of 10% by mass or less. The component content of 0.15 mm or less can be obtained by dividing the mass of the maleimide monomer (B) remaining in the tray by the mass of the entire sample used for the measurement.

Further, when the maleimide monomer (B) is brought into contact with water, it may ring-open to produce a maleamic acid. This causes problems such as a decrease in polymerization stability and coloring. Therefore, it is better that the number of fine particles having a large specific surface area is small.
From this point of view, in the method for producing a methacrylic resin of the present embodiment, as described above, specifically, the content of a particle size component of 0.15 mm or less is 10% by mass or less. Preferably it is 5 mass% or less, More preferably, it is 3 mass% or less.

Furthermore, in the polymerization step of copolymerizing the polymerization monomer component constituting the methacrylic resin, in order to increase the polymerization stability, after introducing other monomer species other than the maleimide monomer (B), It is preferable that the maleimide monomer (B) is rapidly dissolved in the other monomer species.
Specifically, the maleimide monomer (B) in a water-dispersed state is first charged into the reaction vessel, and then another liquid monomer species is charged, and the maleimide monomer (B) is converted into the other monomer species. When making it melt | dissolve, it is preferable that content of the component of 9.5 mm or more contained in a maleimide-type monomer (B) is 10 mass% or less from a viewpoint of improving the solubility of a maleimide monomer (B). . More preferably, it is 8 mass% or less, More preferably, it is 5 mass% or less.

In addition, from the viewpoint of preventing metal corrosion and polymerization stability in the case of aqueous suspension polymerization, the acid value of the maleimide monomer (B) is preferably 2.0 or less. More preferably, it is 1.5 or less, More preferably, it is 1.0 or less.
The acid value of the maleimide monomer (B) can be measured by the method of JIS-K-2501-2003.
From the viewpoint of heat resistance of the methacrylic resin, the maleimide monomer (B) is included in 1 to 30% by mass in all monomers used in the method for producing a methacrylic resin of the present embodiment, Preferably it is 1 to 25% by mass, more preferably 3 to 25% by mass, still more preferably 5 to 25% by mass, and even more preferably 5 to 20% by mass.

(Other vinyl monomers copolymerizable with (A) and (B) (C))
In the method for producing a methacrylic resin of the present embodiment, other vinyl monomers (C) (hereinafter referred to as “copolymers”) that can be copolymerized with the component (A) and the component (B) as long as the effects of the present invention are not impaired. Other vinyl monomers (C), (C) component, and (C) may be described) may be used.
The content in the case of using other vinyl monomer units (C) copolymerizable with the component (A) and the component (B) is different depending on the vinyl monomer used, For example, from the viewpoint of reducing the amount of residual monomers and imparting solvent resistance, it is 20% by mass or less, preferably 18% by mass or less, more preferably 15% by mass or less, and still more preferably 12% by mass in all monomer components. Hereinafter, it is particularly preferably 10% by mass or less.
In addition to the desired properties, the content of component (C) is 0.1% by mass or more based on the total monomers from the viewpoint of appropriately imparting desired properties such as chemical resistance, thermal stability, and reactivity. Is preferably 0.5% by mass or more, and more preferably 1% by mass or more.

  The component (C) is not limited to the following, but, for example, an aromatic vinyl monomer represented by the following general formula (3) or acrylic acid represented by the general formula (4) Ester monomers, vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) Ethylene glycol such as acrylate, tetraethylene glycol di (meth) acrylate or the like, esterified with hydroxyl groups at both terminals of acrylic acid or methacrylic acid; 2 such as neopentyl glycol di (meth) acrylate, di (meth) acrylate, etc. The hydroxyl group of each alcohol Those that have been esterified with methacrylic acid; trimethylolpropane, those polyhydric alcohol derivatives such as pentaerythritol was esterified with acrylic acid or methacrylic acid; polyfunctional monomers such as divinylbenzene, and the like.

In the general formula (3), R ₄ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and may have a hydroxyl group on the alkyl group.
n represents an integer of 0 to 5.
R ₅ 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 1 to 8 carbon atoms, and an aryl group having 1 to 8 carbon atoms. R ₅ may be the same group or different groups.
Further, R ₅ may form a ring structure.

In the general formula (4), R ₆ is a hydrogen atom, and R ₇ is an alkyl group having 1 to 18 carbon atoms.

  The component (C) can be used as appropriate according to the required properties. However, when properties such as thermal stability, fluidity, mechanical properties, and chemical resistance are particularly required, an aromatic vinyl-based single component can be used. A monomer (C-1), an acrylate monomer (C-2), and a vinyl cyanide monomer (C-3) can be suitably selected and used suitably.

<Aromatic vinyl monomer (C-1)>
Examples of the aromatic vinyl monomer include, but are not limited to, 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-butylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 1,1-diphenylethylene, isopropenylbenzene (α-methylstyrene), isopropenyltoluene, isopropenylethylbenzene, isopropenylpropylbenzene, isopropenylbutylbenzene, isopropenylpentylbenzene, isopropenylhexylbenzene, isopropenyloctylbenzene, etc. Is mentioned.
These are appropriately selected according to the required characteristics in the final methacrylic resin. Among these, 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.
As a blending ratio (mass ratio) of the aromatic vinyl monomer unit (C-1) and the maleimide monomer (B) when the aromatic vinyl monomer unit (C-1) is used. From the viewpoint of processing fluidity at the time of molding and the effect of reducing silver streaks by reducing the residual monomer, it is preferable to satisfy the following formula.
0.3 ≦ (C-1) / (B) ≦ 5
From the viewpoint of maintaining good color tone and heat resistance, the upper limit value is preferably 5 or less, more preferably 3 or less, and even more preferably 1 or less.
Moreover, it is preferable that it is 0.3 or more from a viewpoint of reducing the remaining maleimide-type monomer (B), More preferably, it is 0.35 or more, More preferably, it is 0.4 or more.
The aromatic vinyl monomer (C-1) described above may be used alone or in combination of two or more.

<Acrylic acid ester monomer (C-2)>
Examples of the acrylate monomer include a compound in which the substituent R ₇ is an alkyl group having 1 to 18 carbon atoms in the general formula (4) as described above. In the methacrylic resin obtained by the production method, from the viewpoint of enhancing weather resistance, heat resistance, fluidity, and thermal stability, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, sec sec acrylate -Butyl, 2-ethylhexyl acrylate, and the like are preferable, and methyl acrylate, ethyl acrylate, and n-butyl acrylate are more preferable, and methyl acrylate is more preferable from the viewpoint of availability.
The content in the case of using the acrylate monomer (C-2) is (A), (A), (A), from the viewpoint of maintaining the heat resistance imparting effect by the maleimide monomer (B) and imparting thermal stability. When the total of B) and (C) components is 100 parts by mass, it is preferably 5 parts by mass or less, more preferably 3 parts by mass or less.
The acrylic ester monomer (C-2) may be used alone or in combination of two or more.

<Vinyl cyanide compound (C-3)>
The vinyl cyanide compound is not particularly limited, and examples thereof include acrylonitrile, methacrylonitrile, vinylidene cyanide, and acrylonitrile is preferably used.
The content in the case of using the vinyl cyanide compound (C-2) is (A), (B) from the viewpoint of maintaining the heat resistance imparting effect by the maleimide monomer (B) and imparting solvent resistance. ), When the total of the components (C) is 100 parts by mass, it is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, still more preferably 12 parts by mass or less, and particularly preferably 10 parts by mass or less. It is.

(Production process of methacrylic resin)
Next, although the method to manufacture a methacrylic resin using the monomer component mentioned above is demonstrated, the manufacturing method of the methacrylic resin of this embodiment is not limited to the method shown below.
The maleimide monomer (B) used in the polymerization step in the method for producing a methacrylic resin of this embodiment is solid at 25 ° C., and is dissolved or finely dispersed in a slurry using a predetermined dispersion medium. Instead, it is put into a reaction vessel in which the polymerization step is carried out in a state dispersed in water, dissolved in another monomer, and used for the reaction. The maleimide monomer (B) is dissolved in the reaction vessel by other monomers such as the methacrylic acid ester monomer (A).
Conventionally, a maleimide monomer (B), which is a solid raw material, is previously dissolved in a monomer species to be copolymerized therewith or in a solvent capable of dissolving the maleimide monomer (B). It was put in and reacted.
However, the solubility of the solid maleimide monomer (B) in the methacrylic acid ester monomer (A) to be copolymerized is low. If necessary, a considerable amount of time is required to dissolve the maleimide monomer (B), and much energy is required by stirring and dissolving for a long time. Also, by setting the temperature higher than normal temperature, the solubility is improved and the dissolution time is shortened, but when the reactive monomer is placed at a high temperature, it is polymerized during dissolution, and in the dissolution tank, Since it becomes easy to solidify by a transfer pipe from the dissolution tank to the reaction tank, continuous productivity is lowered, which is not preferable.
In this embodiment, the maleimide monomer (B) is dissolved by directly supplying the reaction solution in a water-dispersed state without dissolving the solid maleimide monomer (B). Dissolution time can be shortened, and a methacrylic resin can be produced stably.

The methacrylic resin includes a methacrylic acid ester monomer (A), a maleimide monomer (B), and other vinyl-based monomers copolymerizable with the above-described (A) and (B) as necessary. Using the body (C), it can be produced by a suspension polymerization method, a precipitation polymerization method or an emulsion polymerization method, which can be polymerized in an aqueous system.
A suspension polymerization method and an emulsion polymerization method are preferably used, and a suspension polymerization method is more preferably used.
When the polymerization process is carried out by suspension polymerization, when a solid raw material is put into a reaction vessel, if the surface area of the solid raw material is large, hydrolysis occurs due to contact with water, and polymerization proceeds. In some cases, the polymerization state becomes unstable and solidification may be difficult at the end of the polymerization. Moreover, when the obtained resin is exposed to high-temperature and high-humidity conditions, the color tone may deteriorate.
In the method for producing a methacrylic resin of the present embodiment, in view of the stability of the polymerization state, the content of a particle size component of 0.15 mm or less contained in the maleimide monomer (B) is 10% by mass or less. did. Thus, even if the solid maleimide monomer (B) is not dissolved but dispersed in water and charged into the reaction vessel and reacted, the maleimide monomer (B) powder having a large surface area Can be effectively prevented from hydrolyzing by ring contact with water, ring-opening, becoming acidic and destabilizing the polymerization system, while maintaining polymerization stability and shortening the polymerization time. In addition, it can be stably produced, and the production of by-products such as amines derived from hydrolysis of the maleimide monomer (B) is also suppressed.

<Production method by suspension polymerization method>
Hereinafter, in the method for producing a methacrylic resin of the present embodiment, a suspension polymerization method that can be particularly preferably used will be described as an example, but the method is not limited to the suspension polymerization method.
When producing by suspension polymerization such as organic suspension polymerization method or inorganic suspension polymerization method, maleimide monomer (B) dispersion step, polymerization step using stirring device described later, washing step, dehydration step Through a drying process, a particulate methacrylic resin can be produced. Usually, an aqueous suspension polymerization method using water as a medium is preferably used.

<Dispersing process>
In the method for producing a methacrylic resin of this embodiment, the maleimide monomer (B) is first dispersed in water in a predetermined dispersion tank, and then charged into a reaction tank in which polymerization is performed.
The type of water to be dispersed is not particularly specified as long as the effects of the present invention are not impaired. For example, ion exchange water, deionized water, pure water, distilled water and the like can be mentioned.
When the maleimide monomer (B) is brought into contact with water, the ring-opening tends to generate N-substituted maleamic acid, further primary amine, maleic acid, and the like. Etc. tend to deteriorate.
In this embodiment, when the maleimide monomer (B) is dispersed in water in the dispersion tank, it is preferable that the temperature be such that the maleimide monomer hardly melts.
When the maleimide monomer (B) is dispersed in water and added, the temperature of the water used for the use is determined by the addition of the maleimide monomer (B) due to the melting of the maleimide monomer (B). From the viewpoints of suppressing decomposition, production efficiency, and improving the color tone of the resulting methacrylic resin, the temperature is preferably 20 ° C. or more lower than the melting point of the maleimide monomer (B). Preferably, the temperature is 25 ° C. or more lower than the melting point, more preferably 30 ° C. or lower than the melting point.
Specifically, it is preferably 80 ° C. or less, more preferably 70 ° C. or less, further preferably less than 60 ° C., and even more preferably 55 ° C. or less. The minimum temperature preferred for the charging is preferably a temperature at which water to be used does not solidify, and is preferably 0 ° C. or higher. More preferably, it is 5 degreeC or more, More preferably, it is 10 degreeC or more.

The pH of the water to be used is preferably 5 to 10, more preferably 5 to 8, more preferably 5 to 7.5, from the viewpoint of inhibiting hydrolysis of the maleimide monomer (B). Particularly preferred is 5.5 to 7.5.
The amount of water to be dispersed may be an amount that does not exceed the total amount required for the polymerization reaction.
The preferable amount of water for dispersing the maleimide monomer (B) is preferably selected in the range of 10 to 100% when the total amount of water used in the polymerization reaction is 100%.
After the maleimide monomer (B) dispersed in water is transferred to the reaction tank, the maleimide monomer (B) remaining in the dispersion tank and the piping is washed and further transferred to the reaction tank. Since the maleimide monomer (B) can be introduced into the reaction vessel, the amount of water used for initially dispersing the maleimide monomer (B) in the dispersion vessel is the total amount of water used in the polymerization reaction. Is preferably 10 to 99%, more preferably 20 to 95%, still more preferably 30 to 95%, and particularly preferably 50 to 90%.

The time for dispersing the maleimide monomer (B) in water may be a time for uniformly dispersing the maleimide monomer (B), generally 1 to 60 minutes, preferably 3 It is -45 minutes, More preferably, it is 5-40 minutes, More preferably, it is 5-30 minutes, More preferably, it is 10-30 minutes.
As a dispersion tank suitably used in the dispersion step, a known container with a stirrer, a so-called stirrer, is used. Stirring devices with stirring blades such as blades (retracted blades), turbine blades, bull margin blades, max blend blades, full zone blades, ribbon blades, squid blades, supermix blades, intermig blades, special blades, axial flow blades, etc. And a known stirring device such as a stirring device having a shovel blade, a stirring device having a chopper blade inside, a stirring device having a disk type, a notch disk type or a screw type inside.
The stirring speed at the time of dispersion depends on the type of the stirring device used, the stirring efficiency of the stirring blade, the capacity of the polymerization tank, etc., but may be any speed that can be quickly dispersed, specifically 1 to 500 revolutions / minute. It is preferable that it is a grade.

After the above dispersion is carried out and the aqueous dispersion of the maleimide monomer (B) is transferred to the reaction tank, the number of times of washing the dispersion tank and further transferring it to the reaction tank is the remaining maleimide monomer (B). Although it can select suitably by quantity, when considering production efficiency, it is preferable that it is 0-5 times. More preferably, it is 0-3 times, More preferably, it is 1-3 times.
The temperature of the washing water when washing and transferring may be the same temperature as the maleimide monomer (B) or a different temperature, and can be appropriately selected within the range of the water temperature.

<Polymerization process>
In the polymerization step, the above-mentioned methacrylic acid ester monomer (A), maleimide monomer (B), and other vinyl monomers (C) as necessary, in a predetermined reaction vessel, Copolymerize.
The predetermined reaction tank is not limited to the following, but for example, a vessel with a stirrer, that is, a stirrer can be used, and a monomer, a suspending agent, which is an appropriate raw material in the stirrer, Polymerization is performed by supplying a polymerization initiator, a chain transfer agent, and other additives as necessary to obtain a methacrylic resin slurry.
During the polymerization, a suspending agent, an aqueous dispersion of maleimide monomer (B), a methacrylic acid ester monomer (A), and other polymerizable vinyl monomers (C ), An additive such as a polymerization initiator, and water as necessary, but the order of addition is not particularly limited as long as the effect of the present invention can be obtained. It is preferable to supply the polymerization initiator together with the methacrylic acid ester monomer (A) and other vinyl monomers (C) for ease of handling.

  In addition, first, when an aqueous dispersion of the maleimide monomer (B) is charged into the reaction vessel, and then another monomer is added, the aqueous dispersion of the maleimide monomer (B) is charged. The stirring time from the start to the addition of another monomer is not particularly limited, but is preferably 1 to 60 minutes, more preferably 3 to 45 minutes, further preferably 5 in consideration of work efficiency. -40 minutes, particularly preferably 5-30 minutes.

The reaction vessel used in the polymerization process for obtaining a methacrylic resin by suspension polymerization, specifically a stirring device which is a container equipped with a stirrer, includes an inclined paddle blade, a flat paddle blade, a propeller blade, an anchor blade , Stirrers with stirring blades such as fouller blades (retreating blades), turbine blades, bull margin blades, max blend blades, full zone blades, ribbon blades, squid blades, supermix blades, intermig blades, special blades, and axial flow blades And a known stirring device such as a stirring device having a shovel blade inside, a stirring device having a chopper blade inside, and a stirring device having a disk-type, notched disk-type or screw-type rotating disk inside.
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 it is possible to obtain an appropriate particle size, and a component having a particle size of less than 0.15 mm Considering that the amount can be reduced, polymerization stability and the like, it is preferably about 1 to 500 revolutions / minute.

The temperature in the reaction vessel when the raw material other than the maleimide monomer (B) constituting the methacrylic resin is supplied to the reaction vessel may be within a range in which the effect of the present invention can be exhibited. And from the viewpoint of color tone stability of the resulting resin, it is preferably 0 ° C. or higher and 20 ° C. or lower than the melting point of the maleimide monomer (B).
The temperature is more preferably 25 ° C. or more, and further preferably 30 ° C. or more.
Specifically, the temperature is preferably 80 ° C. or lower, more preferably 70 ° C. or lower, still more preferably less than 60 ° C., and still more preferably 55 ° C. or lower. The minimum temperature preferred for the charging is preferably a temperature at which water used for solidification does not solidify, and more preferably 0 ° C. or higher. More preferably, it is 5 degreeC or more, More preferably, it is 10 degreeC or more.

The temperature of the aqueous dispersion of the maleimide monomer (B) when supplying the aqueous dispersion of the maleimide monomer (B) to the reaction vessel is due to the melting of the maleimide monomer (B). From the viewpoint of suppressing hydrolysis of the maleimide monomer (B), production efficiency, and improving the color tone of the resulting methacrylic resin, the temperature should be 20 ° C. or more lower than the melting point of the maleimide monomer (B). preferable. Preferably, the temperature is 25 ° C. or more lower than the melting point, more preferably 30 ° C. or lower than the melting point.
Specifically, it is preferably 80 ° C. or less, more preferably 70 ° C. or less, further preferably less than 60 ° C., and even more preferably 55 ° C. or less. The minimum temperature preferred for the charging is preferably a temperature at which water to be used does not solidify, and is preferably 0 ° C. or higher. More preferably, it is 5 degreeC or more, More preferably, it is 10 degreeC or more.
If the temperature is higher than the “temperature lower by 20 ° C. or more than the melting point”, the maleimide partially melts in the aqueous dispersion, so that hydrolysis is accelerated, the pH in the reaction system is lowered, the polymerization stability is lowered, and the aggregation is reduced. Aggregation and maleimide degradation products tend to increase.

The polymerization temperature in the suspension polymerization step is preferably 40 ° C. or higher and 90 ° C. or lower in consideration of productivity and the amount of aggregates produced. More preferably, it is 50 degreeC or more and 85 degrees C or less, More preferably, it is 60 degreeC or more and 85 degrees C or less, More preferably, it is 65 degreeC or more and 83 degrees C or less.
When manufacturing by suspension polymerization, the time (polymerization time) from the introduction of the monomer component containing the methacrylic ester monomer (A) to the exothermic peak effectively suppresses the exotherm during the polymerization. From the viewpoint of enhancing the polymerization stability, it is preferably 30 minutes or longer and 240 minutes or shorter. More preferably, it is 45 minutes or more and 210 minutes or less, More preferably, it is 60 minutes or more and 210 minutes or less, More preferably, it is 60 minutes or more and 180 minutes or less, More preferably, it is 90 minutes or more and 180 minutes or less.

Further, from the viewpoint of reducing the residual monomer, it is preferable to raise the temperature to a temperature higher than the polymerization temperature after the polymerization step and hold it for a certain time. Since the temperature at the time of holding | maintenance can raise a polymerization degree, it is preferable that it is temperature higher than polymerization temperature, and it is preferable to heat up 5 degreeC or more from polymerization temperature. When raising temperature, it is preferable that it is below the glass transition temperature of the methacrylic resin obtained from a viewpoint of preventing aggregation of the polymer obtained. Specifically, it is 120 ° C. or lower, preferably 100 ° C. or lower, more preferably 80 ° C. or higher and 100 ° C. or lower, still more preferably 85 ° C. or higher and 100 ° C. or lower, even more preferably 88 ° C. or higher and 100 ° C. or lower. Preferably they are 90 degreeC or more and 100 degrees C or less.
The time for maintaining the temperature after the temperature rise is preferably 15 minutes or more and 360 minutes or less, more preferably 30 minutes or more and 240 minutes or less, more preferably 30 minutes or more and 180 minutes, in consideration of the reduction efficiency of the residual monomer. Hereinafter, it is still more preferably 30 minutes or longer and 150 minutes or shorter. If it is the said range, it is possible to reduce the amount of residual monomers effectively.
By carrying out the polymerization according to the polymerization temperature and holding time described above, methacrylic resin particles having a small amount of residual monomer and a small angle of repose can be produced after a drying step described later.

<Washing process>
The methacrylic resin slurry obtained through the above polymerization step is preferably subjected to operations such as acid washing, water washing, and alkali washing in order to remove the suspending agent.
What is necessary is just to select the optimal frequency | count from the work efficiency and the removal efficiency of a suspension agent as the frequency | count of performing these washing | cleaning operation, and you may repeat once or several times.
What is necessary is just to select the optimal temperature in consideration of the removal efficiency of a suspension agent, the coloring degree of the copolymer obtained, etc. as temperature at the time of washing | cleaning, and it is preferable that it is 20-100 degreeC. More preferably, it is 30-95 degreeC, More preferably, it is 40-95 degreeC.
Moreover, it is preferable that the washing | cleaning time per time at the time of washing | cleaning is 10 to 180 minutes from a viewpoint of washing | cleaning efficiency, a repose angle reduction effect, and the simplicity of a process, More preferably, it is 20 to 150 minutes.
The pH of the cleaning solution used at the time of the cleaning may be within a range where the suspension can be removed, but is preferably pH 1-12. The pH for acid washing is preferably pH 1-5, more preferably pH 1.2-4, from the viewpoint of the removal efficiency of the suspending agent and the color tone of the resulting copolymer. The acid used at that time is not particularly limited as long as it can remove the suspending agent. Conventionally known inorganic acids and organic acids can be used. As an example of the acid that is preferably used, the inorganic acid includes hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, boric acid and the like, and each may be used in a diluted solution diluted with water or the like. Examples of the organic acid include those having a carboxyl group, a sulfo group, a hydroxy group, a thiol group, or an enol. Considering the effect of removing the suspending agent and the color tone of the resulting resin, more preferred are nitric acid, sulfuric acid, and organic acids having a carboxyl group.
After the acid cleaning, it is preferable to further perform water washing or alkali washing from the viewpoint of reducing the color tone and angle of repose of the polymer obtained.
The pH of the alkaline solution when performing alkali cleaning is preferably pH 7.1 to 12, more preferably pH 7.5 to 11, and still more preferably 7.5 to 10.5.
As the alkaline component used for alkali cleaning, tetraalkylammonium hydroxide, alkali metal hydroxide, alkaline earth metal hydroxide and the like are preferably used. Alkali metal hydroxides and alkaline earth metal hydroxides are more preferable, and lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, magnesium hydroxide, hydroxide are more preferable. Calcium and barium hydroxide are more preferable, lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide and calcium hydroxide are more preferable, and sodium hydroxide and potassium hydroxide are still more preferable.
These alkaline components can be used by adjusting the pH by diluting with water or the like.

<Dehydration process>
As a method for separating the polymer particles from the polymer slurry of the obtained methacrylic resin, a conventionally known method can be applied.
For example, a dehydration method using a centrifuge that shakes off water using centrifugal force, a method of separating water by sucking and removing water on a porous belt or a filtration membrane, and the like can be mentioned.

<Drying process>
The water-containing polymer obtained through the above-described dehydration step can be recovered by performing a drying treatment by a known method.
For example, hot air drying for drying by sending hot air into the tank from a hot air blower or blow heater, etc., vacuum drying for drying by heating as necessary after reducing the pressure inside the system, and the obtained polymer For example, barrel drying for removing moisture by rotating the container in a container, spin drying for drying using centrifugal force, and the like. These methods may be used alone or in combination.
The water content of the obtained methacrylic resin is preferably 0.01% by mass to 1% by mass, more preferably 0.05% by mass to 1% by mass, considering the handleability, color tone, and the like of the obtained resin. %, More preferably 0.1% by mass to 1% by mass, and still more preferably 0.27% by mass to 1% by mass. The water content of the resulting methacrylic resin can be measured using the Karl Fischer method.

When a methacrylic resin is produced using the suspension polymerization method described above, the resulting methacrylic resin is usually substantially spherical, but some aggregates may be formed.
The aggregate refers to a residue remaining on the sieve when the obtained polymer is passed through a 1.68 mm mesh sieve.
When the aggregate remains in the methacrylic resin, the color tone of the obtained methacrylic resin tends to decrease. The amount of aggregates in the methacrylic resin is preferably 1.2% by mass or less, and more preferably 1.0% by mass or less.
The agglomerate content was passed through a 1.68 mm mesh sieve, and the weight of what was left on the sieve was dried in a drying oven at 80 ° C. for 12 hours. The resulting weight was the total amount of raw materials The aggregate production amount (mass%) can be calculated by dividing the above.

The average particle diameter of the methacrylic resin obtained using the suspension polymerization method described above is preferably 0.1 mm or more in consideration of workability during molding and extrusion, etc., and a molded piece obtained by molding In consideration of the color tone, the thickness is more preferably from 0.1 mm to 1 mm, further preferably from 0.1 mm to 0.5 mm, and still more preferably from 0.1 mm to 0.4 mm.
The average particle diameter is, for example, a sieve (Tokyo Screen JTS-200-45-44 (aperture 500 μm), 34 (aperture 425 μm), 35 (aperture 355 μm), 36 (aperture 300 μm) based on JIS-Z8801. ), 37 (aperture 250 μm), 38 (aperture 150 μm), 61 (a saucer)), and each sieve when subjected to a vibration force MAX for 10 minutes using a screening tester TSK B-1. It is possible to measure by measuring the particle mass remaining in the sample and determining the particle diameter when the mass is 50%.
The smaller the content of amines in the obtained methacrylic resin, the better. From the viewpoint of color tone stability, it is preferably 0.12% or less, more preferably 0.1% or less, further preferably 0.08% or less, and still more preferably 0.06% or less.
From the viewpoint of color tone stability, the content of amines is preferably as low as possible and more preferably not included. That is, 0% is preferable. However, it may be contained in a small amount, may be contained in 0.0001% or more, and further may be contained in 0.0005% or more, as long as the effect on the characteristics is within a practical range. It may be contained 0.001% or more.
Here, the amines contained in the methacrylic resin refer to primary amines derived from the maleimide used. For example, when N-phenylmaleimide is used, it means aniline, and when N-cyclohexylmaleimide is used, it means cyclohexylamine.
The content of amines can be measured using a conventionally known method and can be quantified using gas chromatography.

In this embodiment, when a methacrylic resin is produced by a suspension polymerization method, a conventionally known suspending agent can be suitably used.
As for the suspending agent, water may be added to the reaction tank, and then the maleimide monomer (B) or other monomer species may be added, or after the maleimide monomer (B) is added. The suspending agent may be added before or after adding other monomer species after adding water.
The addition amount of the suspending agent can be appropriately selected depending on the polymerization stability during suspension polymerization and the particle size required for the resulting methacrylic resin particles. The total amount of monomer species used for the polymerization is 100 parts by mass. When it is, it is preferable that they are 0.01 mass part or more and 2 mass parts or less. More preferably, they are 0.02 mass parts or more and 1.5 mass parts or less, More preferably, they are 0.03 mass parts or more and 1.2 mass parts or less. When the amount exceeds 2 parts by mass, a large amount of fine particles having a small particle diameter are generated, and problems are likely to occur in the post-treatment process. On the other hand, when the amount is less than 0.01 parts by mass, the particles are too large and the polymerization stability tends to be lowered.
Examples of the suspension include, but are not limited to, for example, tricalcium phosphate, hydroxyapatite, magnesium pyrophosphate, magnesium phosphate, aluminum hydroxide, ferric hydroxide, titanium hydroxide, water Particulate inorganic suspensions such as magnesium oxide, barium phosphate, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, talc, kaolin, bentonite, ethyl cellulose, hydroxypropyl methylcellulose, polyvinyl alcohol and polyacetic acid An organic suspending agent such as a partially saponified vinyl product can be used. These suspending agents may be used alone or in combination of two or more.

In the method for producing a methacrylic resin of the present embodiment, in addition to the suspension polymerization method described above, the polymerization degree of the polymer to be produced is adjusted in various polymerization methods, that is, the polymerization step in the bulk polymerization method and the emulsion polymerization method. For the purpose, a polymerization initiator may be used.
When using a polymerization initiator, the method of mixing and using in a solution containing a methacrylic ester monomer (A) and other vinyl monomers (C) is preferable.
As a polymerization initiator, when performing radical polymerization, a 10-hour half-life temperature is 40 to 120 degreeC. The polymerization initiator is not limited to the following examples. For example, di-t-butyl peroxide, lauroyl peroxide, stearyl peroxide, benzoyl peroxide, t-butyl peroxyneodecanate, t- Butyl peroxypivalate, dilauroyl peroxide, dicumyl peroxide, t-butylperoxy-2-ethylhexanoate, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane Organic peroxides such as 1,1-bis (t-butylperoxy) cyclohexane, azobisisobutyronitrile, azobisisovaleronitrile, 1,1-azobis (1-cyclohexanecarbonitrile), 2, 2'-azobis-4-methoxy-2,4-azobisisobutyronitrile, 2,2'- Zobisu-2,4-dimethylvaleronitrile, mention may be made of conventional radical polymerization initiator azo such as 2,2'-azobis-2-methylbutyronitrile.
These may be used alone or in combination of two or more.
A combination of these radical polymerization initiators and an appropriate reducing agent may be used as a redox initiator.
These polymerization initiators are generally used in the range of 0 to 1 part by mass with respect to 100 parts by mass of the total amount of all monomers used, taking into consideration the polymerization temperature and the half-life of the initiator. Can be selected as appropriate.
When selecting bulk polymerization method, cast polymerization method, suspension polymerization method, from the viewpoint of preventing coloring of methacrylic resin, peroxide initiators lauroyl peroxide, decanoyl peroxide, and t-butylperoxy- 2-ethylhexanoate and the like can be particularly preferably used, and lauroyl peroxide is particularly preferably used.

In the method for producing a methacrylic resin of this 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.
For example, the molecular weight can be controlled by using chain transfer agents such as alkyl mercaptans, dimethylacetamide, dimethylformamide, triethylamine, etc., dithiocarbamates, triphenylmethylazobenzene, iniferters such as tetraphenylethane derivatives, etc. It is possible to adjust the molecular weight by adjusting the amount of these added.
When these additives are used, alkyl mercaptans are preferably used from the viewpoint of handleability and stability. For example, n-butyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-tetra Examples include decyl mercaptan, n-octadecyl mercaptan, 2-ethylhexyl thioglycolate, ethylene glycol dithioglycolate, trimethylolpropane tris (thioglycolate), pentaerythritol tetrakis (thioglycolate) and the like.
These can be appropriately added according to the required molecular weight, but generally used in the range of 0.001 to 3 parts by mass with respect to 100 parts by mass of the total amount of all monomers used. .
Other molecular weight control methods include a method of changing the polymerization method, a method of adjusting the amount of the polymerization initiator, and a method of changing the polymerization temperature.
As these molecular weight control methods, only one type of method may be used alone, or two or more types may be used in combination.

[Methacrylic resin]
According to the manufacturing method of this embodiment mentioned above, methacrylic acid ester monomer unit (A): 50-99 mass%, maleimide-type monomer unit (B): 1-30 mass%, said (A) and Other monomer units (C) copolymerizable with (B): A methacrylic resin containing 0 to 20% by mass is obtained.

(Methacrylic resin weight average molecular weight, number average molecular weight)
The methacrylic resin produced by the methacrylic resin production method of the present embodiment preferably has a weight average molecular weight of 60,000 to 300,000. A methacrylic resin in this range is excellent in mechanical strength, solvent resistance and fluidity. More preferably, it is 60,000-250,000, More preferably, it is 70,000-230,000.
The molecular weight distribution (weight average molecular weight / number average molecular weight: Mw / Mn) is preferably 1.5 or more and 5 or less in consideration of the balance between fluidity, mechanical strength, and solvent resistance. More preferably, it is 1.5 or more and 4.5 or less, More preferably, it is 1.6 or more and 3 or less, More preferably, it is 1.6 or more and 2.5 or less.
The weight average molecular weight, number average molecular weight, and peak molecular weight of the methacrylic resin produced by the methacrylic resin production method of the present embodiment are measured by gel permeation chromatography (GPC).
Specifically, using a standard methacrylic resin that is known in advance as a reagent and has a monodispersed weight average molecular weight, number average molecular weight, and peak molecular weight, and an analytical gel column that elutes a high molecular weight component first, elution time and Create a calibration curve from the weight average molecular weight.
Next, from the obtained calibration curve, the weight average molecular weight, number average molecular weight, and peak molecular weight of the sample of the methacrylic resin to be measured can be obtained.

(Methacrylic resin composition)
The methacrylic resin produced according to the present embodiment can be made into a methacrylic resin composition by combining with a predetermined other resin and a predetermined additive described later.

<Other resins>
Other resins to be combined with the methacrylic resin are not particularly limited as long as the characteristics required for the methacrylic resin can be exhibited, and known thermoplastic resins can be used.
Examples of other resins include, but are not limited to, polypropylene resins, polyethylene resins, polystyrene resins, syndiotactic polystyrene resins, ABS resins, methacrylic resins, AS resins, BAAS. Resin, MBS resin, AAS resin, biodegradable resin, polycarbonate-ABS resin alloy, polybutylene terephthalate, polyethylene terephthalate, polypropylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate and other polyalkylene arylate resins; polyamide resin , Polyphenylene ether resins, polyphenylene sulfide resins, phenol resins and the like.
In particular, AS resin and BAAS resin are preferable for improving fluidity, ABS resin and MBS resin are preferable for improving impact resistance, and polyester resin is preferable for improving chemical resistance.
In addition, polyphenylene ether resins, polyphenylene sulfide resins, phenol resins, and the like can be expected to have an effect of improving flame retardancy.
These resins may be used alone or in combination of two or more.

<Additives>
In order to impart various properties such as rigidity and dimensional stability to the methacrylic resin obtained by the production method of the present embodiment, a predetermined additive may be added.
Additives are not limited to the following, but include, for example, various stabilizers such as antioxidants, ultraviolet absorbers, heat stabilizers, light stabilizers; plasticizers (paraffinic process oils, naphthenic process oils). , Aromatic process oils, paraffins, organic polysiloxanes, mineral oils), flame retardants (eg, phosphorus compounds such as organic phosphorus compounds, red phosphorus, inorganic phosphates, halogens, silicas, silicones, etc.), Flame retardant aids (for example, antimony oxides, metal oxides, metal hydroxides, etc.), curing agents (diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, diethylaminopropylamine, 3,9-bis ( 3-aminopropyl) -2,4,8,10-tetraoxaspiro [5,5] undecane, mensendiamy , Amines such as isophoronediamine, N-aminoethylpiperazine, m-xylenediamine, m-phenylenediamine, diaminophenylmethane, diaminodiphenylsulfone, dicyandiamide, adipic acid dihydrazide, and phenols such as phenol novolac resin and cresol novolac resin Resins, polymercaptans such as liquid polymercaptan, polysulfide, maleic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, anhydrous Pyromellitic acid, methylcyclohexene tetracarboxylic anhydride, dodecyl succinic anhydride, trimellitic anhydride, chlorendic acid anhydride, benzophenone tetracarboxylic acid Water, acid anhydrides such as ethylene glycol bis (anhydrotrimate)), curing accelerators (2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2- Undecylimidazole, 2-heptadecylimidazole, imidazoles such as 2-phenyl-4-methylimidazole, organic phosphines such as triphenylphosphine and tributylphosphine, benzyldimethylamine, 2-dimethylaminomethyl) phenol, 2,4 , 6-tris (diaminomethyl) phenol, tertiary amines such as tetramethylhexanediamine, triphenylphosphine tetraphenylborate, tetraphenylphosphonium tetraphenylborate, triethylaminetetraphenylborate, etc. Quinoid compounds such as boron salt, 1,4-benzoquinone, 1,4-naphthoquinone, 2,3-dimethyl-1,4-benzoquinone, 2,6-dimethylbenzoquinone, 2,3-dimethoxy-1,4-benzoquinone, etc. ), Antistatic agent (for example, polyamide elastomer, quaternary ammonium salt, pyridine derivative, aliphatic sulfonate, aromatic sulfonate, aromatic sulfonate copolymer, sulfate ester salt, polyhydric alcohol partial ester , Alkyldiethanolamine, alkyldiethanolamide, polyalkylene glycol derivatives, betaines, imidazoline derivatives, etc.), conductivity imparting agents, stress relieving agents, mold release agents (alcohols, esters of alcohols and fatty acids, alcohols and dicarboxylic acids Ester, silicone oil, etc.), crystallization accelerator, additive Decomposition inhibitors, lubricants (eg, higher fatty acids such as stearic acid, behenic acid, zinc stearate, calcium stearate, magnesium stearate, and metal salts thereof, higher fatty acid amides such as ethylene bisstearamide), impact Giving agent, sliding property improver (hydrocarbon such as low molecular weight polyethylene, higher alcohol, polyhydric alcohol, polyglycol, polyglycerol, higher fatty acid, higher fatty acid metal salt, fatty acid amide, ester of fatty acid and aliphatic alcohol , Full esters or partial esters of fatty acids and polyhydric alcohols, full esters or partial esters of fatty acids and polyglycols, silicones, fluororesins, etc.), compatibilizers, nucleating agents, reinforcing agents, flow control agents, dyes (Nitroso dye, nitro dye, azo dye, stilbene azo dye, ketoimi Dye, triphenylmethane dye, xanthene dye, acridine dye, quinoline dye, methine / polymethine dye, thiazole dye, indamine / indophenol dye, azine dye, oxazine dye, thiazine dye, sulfur dye, aminoketone / oxyketone dye, anthraquinone dye , Indigoid dyes, phthalocyanine dyes, etc.), sensitizers, colorants (titanium oxide, carbon black, titanium yellow, iron oxide pigments, ultramarine, cobalt blue, chromium oxide, spinel green, lead chromate pigments, cadmium Inorganic pigments such as azo pigments, azo lake pigments, benzimidazolone pigments, diazolide pigments, azo pigments such as condensed azo pigments, phthalocyanine pigments such as phthalicyanine blue and phthalocyanine green, isoindolinone pigments, quinophthalo Organic pigments such as pigments, quinacridone pigments, perylene pigments, anthraquinone pigments, perinone pigments, condensed polycyclic pigments such as dioxazine violet, scaly aluminum metallic pigments, used to improve weld appearance Spherical aluminum pigments, mica powders for pearl-like metallic pigments, other metallic pigments such as glass coated with inorganic polyhedral particles such as glass, etc.), thickeners, anti-settling agents, anti-sagging agents, Fillers (glass fibers, fibrous reinforcing agents such as carbon fibers, glass beads, calcium carbonate, talc, clay, etc.), antifoaming agents (silicone antifoaming agents, surfactants, polyethers, higher alcohols, etc.) Organic antifoaming agent, etc.), coupling agent, light diffusing fine particles, rust preventive agent, antibacterial / antifungal agent, antifouling agent, conductive polymer And the like.

Examples of the light diffusing fine particles include inorganic fine particles such as alumina, titanium oxide, calcium carbonate, barium sulfate, silicon dioxide, and glass beads, and organic fine particles such as styrene crosslinked beads, MS crosslinked beads, and siloxane crosslinked beads.
Further, hollow crosslinked fine particles made of a highly transparent resin material such as acrylic resin, polycarbonate resin, MS resin, and cyclic olefin resin, hollow fine particles made of glass, and the like are also included.
In the inorganic fine particles, alumina, titanium oxide and the like are more preferable.
The light diffusing fine particles may be used alone or in combination, and is not limited at all.
Here, the refractive index of the light diffusing fine particles is preferably 1.7 to 3.0, more preferably 1.7 to 2.5, and still more preferably 1.7 to 2.0. If the refractive index is less than 1.7, the scattering property becomes too weak. On the other hand, if it exceeds 3.0, the scattering in the vicinity of the lamp becomes too strong, and as a result, uneven brightness and unevenness in emitted light color tone are likely to occur. Absent.
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 fine particles, for example, the fine particles are immersed in a liquid whose refractive index can be changed little by little, and the fine particle interface is observed while changing the refractive index of the liquid. The method of measuring the refractive index of the liquid at the time is mentioned. An Abbe refractometer or the like can be used to measure the refractive index of the liquid.
The average particle diameter 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 still more preferably 0.4 to 5 μm. An average particle diameter of 20 μm or less is preferable because light loss due to back reflection or the like is suppressed and incident light can be efficiently diffused to the light emitting surface side. In addition, it is preferable that the average particle diameter is 0.1 μm or more because emitted light can be diffused and desired surface emission luminance and diffusibility can be obtained.
Further, the content of the light diffusing fine particles in the methacrylic resin composition is 0.0001 to 0.03 mass 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. Parts, preferably 0.0001 to 0.01 parts by weight.

Examples of the heat stabilizer include, but are not limited to, phosphorus antioxidants such as hindered phenol antioxidants and phosphorus processing stabilizers. Inhibitors are preferred.
Examples of the hindered phenol antioxidant include, but are not limited to, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], thiodiethylene bis [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 ″-(mesitylene-2,4,6-triyl) tri-p-cresol, 4,6-bis ( Octylthiomethyl) -o-cresol, 4,6-bis (dodecylthiomethyl) -o-cresol, ethylenebis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) ) Propionate], hexamethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,3,5-tris (3,5-di-tert-butyl-4-hydroxy Benzyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 1,3,5-tris [(4-tert-butyl-3-hydroxy-2,6-xyline ) 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-triazin-2-ylamine) phenol and the like. In particular, pentaerythritol terakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] is preferable.
Commercially available phenolic antioxidants may be used as hindered phenolic antioxidants. Examples of such commercially available phenolic antioxidants include, but are not limited to, Knox 1010 (Irganox 1010: pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], manufactured by Ciba Specialty Chemicals), Irganox 1076 (Irganox 1076: octadecyl-3) -(3,5-di-t-butyl-4-hydroxyphenyl) propionate, manufactured by Ciba Specialty Chemicals), Irganox 1330 (Irganox 1330: 3, 3 ', 3 ", 5, 5', 5) '' -Hexa-t-butyl-a, a ', a''-(mesitylene-2, 4,6-triyl) tri-p-cresol, manufactured by Ciba Specialty Chemicals, Irganox 3114: 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl ) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, manufactured by Ciba Specialty Chemicals), Irganox 3125 (Irganox 3125, manufactured by Ciba Specialty Chemicals), Sumilizer BHT (Sumilizer BHT, manufactured by Sumitomo Chemical), Cyanox 1790 (Cyanox 1790, manufactured by Cytec), Sumilizer GA-80 (Sumilizer GA-80, manufactured by Sumitomo Chemical), Sumitizer GS (Sumilizer GS, manufactured by Sumitomo Chemical), (Vitamin E) (Eisai) And the like. Among these also, especially Irganox 1010, Irganox 1076, also be used preferably used Sumilizer GS, and the like. They only singly or in combination of two or more.
Moreover, as a phosphorus antioxidant, although not limited to the following, for example, tris (2,4-di-t-butylphenyl) phosphite, bis (2,4-bis (1,1- Dimethylethyl) -6-methylphenyl) ethyl ester phosphorous acid, tetrakis (2,4-di-t-butylphenyl) (1,1-biphenyl) -4,4′-diylbisphosphonite, bis (2 , 4-Di-t-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,4-dicumylphenyl) penta Erythritol diphosphite, tetrakis (2,4-t-butylphenyl) (1,1-biphenyl) -4,4′-diylbisphosphonite, di-t-butyl- - cresyl - phosphonite, and the like.
Furthermore, a commercially available phosphorus antioxidant may be used as the phosphorus antioxidant. Examples of such commercially available phosphorus antioxidants are not limited to the following, but include Irgaphos 168 ( Irgafos 168: Tris (2,4-di-t-butylphenyl) phosphite, manufactured by Ciba Specialty Chemicals, Irgafos 12 (Irgafos 12: Tris [2-[[2,4,8,10-tetra- t-butyldibenzo [d, f] [1,3,2] dioxaphosphine-6-yl] oxy] ethyl] amine, manufactured by Ciba Specialty Chemicals, Irgafos 38 (Irgafos 38: Bis (2 , 4-Bis (1,1-dimethylethyl) -6-methylphenyl) ethyl ester phosphorous acid, manufactured by Ciba Specialty Chemicals) ADK STAB 329K (ADK STAB 329K, manufactured by Asahi Denka), ADK STAB PEP36 (ADK STAB PEP36, manufactured by Asahi Denka), ADK STAB PEP-8 (ADK STAB PEP-8, manufactured by Asahi Denka), Sandstab P-EPQ (manufactured by Clariant), Weston 618 (manufactured by Weston 618, manufactured by GE), Weston 619G (manufactured by Weston 619G, manufactured by GE), Ultranox 626 (manufactured by Ultranox 626, manufactured by GE), Sumilizer GP (manufactured by Sumitizer GP, manufactured by Sumitomo Chemical), and the like. These may be used alone or in combination of two or more.
The amount of the heat stabilizer mentioned above may be an amount that exhibits the effect of the present invention, and if it is excessively added, a problem 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, still more preferably 1 part by mass or less, still more preferably 0.8 parts by mass or less, and still more preferably 0.8 parts by mass or less with respect to 100 parts by mass of the resin. 01 parts by mass or more and 0.8 parts by mass or less.

Examples of the ultraviolet absorber include, but are not limited to, for example, benzotriazole compounds, benzotriazine compounds, benzoate compounds, benzophenone compounds, oxybenzophenone compounds, phenol compounds, oxazole compounds, Examples include malonic acid ester compounds, cyanoacrylate compounds, lactone compounds, salicylic acid ester compounds, and benzoxazinone compounds. In particular, benzotriazole compounds and benzotriazine compounds are preferable. These may be used alone or in combination of two or more.
From the viewpoint of ensuring good moldability of the methacrylic resin composition, the ultraviolet absorber preferably has a vapor pressure (P) at 20 ° C. of 1.0 × 10 ⁻⁴ Pa or less. It is more preferably 10 ⁻⁶ Pa or less, and further preferably 1.0 × 10 ⁻⁸ Pa or less.
Here, the favorable moldability of the methacrylic resin composition means, for example, that the low-molecular compound adheres less to the roll when it is molded as a film. When it adheres to the roll, it reattaches to the surface, which causes the appearance to deteriorate and the optical characteristics to deteriorate.
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 even more preferably 160 ° C. or higher. preferable.
The ultraviolet absorber preferably has a weight reduction rate of 50% or less, more preferably 30% or less, and more preferably 15% or less when the temperature is increased from 23 ° C. to 260 ° C. at a rate of 20 ° C./min. More preferably, it is more preferably 10% or less, still more preferably 5% or less.
The blending amount of the ultraviolet absorber may be an amount that exhibits the effect of the present invention, but if it is excessively added, a problem such as bleeding out at the time of processing may occur. The amount 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, and still more preferably 0.01 parts by mass with respect to 100 parts by mass. It is not less than 0.8 parts by mass.

(Processing of methacrylic resin and methacrylic resin composition)
Examples of a method for processing a methacrylic resin, or mixing various additives of the methacrylic resin and other resins to process a methacrylic resin composition include, for example, an extruder, a heating roll, a kneader, and a roller mixer. And a kneading method using a kneading machine such as a Banbury mixer.
Among these, kneading with an extruder is preferable in terms of productivity.
The kneading temperature may be in accordance with the preferred processing temperature of the polymer constituting the methacrylic resin and other resins to be mixed, and is generally in the range of 140 to 300 ° C, preferably in the range of 180 to 280 ° C.

[Molded body]
The molded body of the present embodiment includes the methacrylic resin described above, and is obtained by molding the above methacrylic resin alone or a resin composition including the methacrylic resin.
As a manufacturing method of the molded body, it can be molded by known methods such as injection molding, sheet molding, blow molding, injection blow molding, inflation molding, T-die molding, press molding, extrusion molding, foam molding, Secondary workability system methods such as pressure forming and vacuum forming can also be used.
Another example is a method in which a resin composition is kneaded and manufactured using a kneader such as a heating roll, kneader, Banbury mixer, extruder, etc., then cooled, pulverized, and further molded by transfer molding, injection molding, compression molding, or the like. Can be mentioned.

[Characteristics of methacrylic resin and molded product]
In the methacrylic resin obtained by the method for producing a methacrylic resin of the present embodiment, and in the methacrylic resin composition using the methacrylic resin, high heat resistance and transparency, and further, distortion under high temperature and high humidity conditions Has excellent moisture and heat resistance.
Further, when it is assumed that an instrument cover, for example, an instrument cover for a vehicle, is produced by molding the methacrylic resin of this embodiment, a polarizing plate is passed through when a material having high birefringence is used during molding. Since the polarized light is seen at the time, when viewed through a polarizing plate such as sunglasses, the visibility is not preferable. In order to solve such a problem, it is necessary to suppress polarization by increasing the molding processing temperature and improve visibility, and further, it is necessary that defects such as silver do not occur even at a high molding processing temperature. For this reason, it is necessary to have excellent thermal stability during molding, and the molded body must have high heat resistance and transparency.

(Heat-resistant)
The methacrylic resin of this embodiment preferably has a VICAT softening temperature of 105 ° C. or higher. More preferably, it is 110 degreeC or more, More preferably, it is 115 degreeC or more, More preferably, it is 117 degreeC or more, Most preferably, it is 120 degreeC or more.
The VICAT softening temperature can be measured according to ISO 306 B50.

(transparency)
From the viewpoint of visibility, the methacrylic resin of this embodiment preferably has a total light transmittance of 70% or more in a molded product having a thickness of 3 mm. More preferably, it is 75% or more, More preferably, it is 80% or more.
Although it is preferable that the total light transmittance is high, practically sufficient visibility can be secured even at 94% or less.
Transparency can be measured by the method described in Examples described later.

(Molding processability)
In the methacrylic resin of this embodiment, it is preferable that defects such as silver do not occur even when the molding temperature is raised and the melt viscosity is lowered to perform the molding process. Specifically, even when 50 shots are continuously formed at a barrel temperature of 290 ° C. and a mold temperature of 60 ° C., it is preferable that almost no molding defects such as silver streaks are observed.

[Use]
The methacrylic resin produced by the production method of the present embodiment and the methacrylic resin composition using the methacrylic resin can be suitably used as materials for various molded products.
Applications of the molded body include, for example, household goods, OA equipment, AV equipment, battery electrical equipment, lighting equipment, housing use, sanitary use, elastic play equipment use, head lamp cover, rear lamp cover, rear combination lamp cover, visor, Vehicle parts such as bug guards, instrument covers, and meter panels, parts for vehicle head-up displays, liquid crystal displays, plasma displays, organic EL displays, field emission displays, rear projection televisions, light guide plates, diffuser plates, Examples include polarizing plate protective films, quarter-wave plates, half-wave plates, viewing angle control films, retardation films such as liquid crystal optical compensation films, display front plates, display substrates, lenses, touch panels, and the like. Used for batteries It can be suitably used in that the transparent base and the like. In addition, in the fields of optical communication systems, optical switching systems, and optical measurement systems, they 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.
The molded body using the methacrylic resin and the resin composition of the present embodiment can be subjected to surface functionalization treatment such as antireflection treatment, transparent conductive treatment, electromagnetic wave shielding treatment, and gas barrier treatment.

  Hereinafter, although a specific Example and a comparative example are given and demonstrated, this invention is not limited to these.

〔material〕
It shows below about the raw material used in the Example and comparative example which are mentioned later.
((A) component: methyl methacrylate (MMA))
: Asahi Kasei Chemicals Co., Ltd. (2.5 ppm of 2,4-di-6-tert-butylphenol as a polymerization inhibitor, manufactured by Chugai Trading Co., Ltd.) Added)
((B) component: maleimide monomer)
(B-1): N-phenylmaleimide (N-PMI)
: Nippon Shokubai Co., Ltd., Imirex (registered trademark) -P, melting point 89 ° C., average particle size of 4 mm, component content of 0.15 mm or less particle size is 0.5 mass%, 9.5 mm or more A particle size component content of 0.00 mass% and an acid value of 0.6 is used.
(B-2): N-phenylmaleimide (N-PMI)
: Nippon Shokubai Co., Ltd., Imirex (registered trademark) -P, melting point 89 ° C., obtained by pulverizing the above (B-1), and having an average particle size of 0.9 mm and a component content of 0.15 mm or less is 16 A material having a mass content of 0.00% by mass with a particle size of 9.5 mm or more is used.
(B-3): N-cyclohexylmaleimide (N-CyMI)
: Made by Nippon Shokubai Co., Ltd., Imirex (registered trademark) -C, melting point 89 ° C., average particle size is 3 mm, component content of particle size of 0.15 mm or less is 0.7 mass%, 9.5 mm or more A component having a particle size component content of 0.00 mass% and an acid value of 0.5 is used.
<Measurement Method of (B) Component Average Content, Component Content of Particle Size of 0.15 mm or Less, and Component Content of Particle Size of 9.5 mm or More>
Sieve based on JIS-Z8801, JTS-200-45-16 (mesh opening 9.5 mm), JTS-200-45-19 (mesh opening 5.6 mm), 21 (mesh opening 4.0 mm), 23, manufactured by Tokyo Screen (Aperture 2.8 mm), 25 (aperture 2.0 mm), 32 (aperture 0.6 mm), 38 (aperture 150 μm), 61 (a saucer) and sieving tester TSK B-1 Using the measured value of the average particle size when sieving with vibration force MAX for 10 minutes, the particle size of 50% by mass was measured to determine the average particle size.
In addition, the content of components having a particle size of 0.15 mm or less was obtained by dividing the mass remaining in the tray by the sample mass used for the measurement.
The component content of 9.5 mm or more was obtained by dividing the mass remaining on the sieve having an opening of 9.5 mm by the sample mass used for the measurement.
<Method for Measuring Acid Value of Component (B)>
The acid value was measured according to JIS-K-2501-2003.
((C) component: other vinyl monomers)
(C-1): Styrene (St)
: Asahi Kasei Chemicals Corporation (C-2-1): Methyl acrylate (MA)
: Mitsubishi Chemical Corporation (C-2-2): Ethyl acrylate (EA)
: Made by Mitsubishi Chemical Corporation (C-3): Acrylonitrile (AN)
: Asahi Kasei Chemicals Corporation

(N-octylmercaptan (NOM)): Arkema Co., Ltd., used as a chain transfer agent (lauroyl peroxide (LPO)): Nippon Oil & Fats Co., Ltd., as a polymerization initiator Use (calcium phosphate): Nihon Kagaku Kogyo Co., Ltd., used as a suspending agent (Calcium carbonate): Shiraishi Kogyo Co., Ltd., used as a suspending agent (Lauryl sulfate) Sodium (sodium lauryl sulfate): Wako Pure Chemical Industries, Ltd., used as a suspension aid

〔Measuring method〕
(I. Measurement of weight average molecular weight)
Based on the area area in the GPC elution curve and the calibration curve, the weight average molecular weight (Mw) of the methacrylic resin was determined.
The following 10 methacrylic resins (manufactured by EasiCal PM-1 Polymer Laboratories) having different molecular weights and known monodispersed weight average molecular weights were used as standard samples for calibration curves.
Weight average molecular weight Standard sample 1 1,900,000
Standard sample 2 790,000
Standard sample 3 281,700
Standard sample 4 144,000
Standard sample 5 59,800
Standard sample 6 28,900
Standard sample 7 13,300
Standard sample 8 5,720
Standard sample 9 1,936
Standard sample 10 1,020
(II. Time required for polymerization)
<1. Dissolution method>
Polymerization required at the time when mixing was started to dissolve the maleimide monomer (B), the methacrylic acid ester monomer (A), and other vinyl monomers (C) as required. At the start of time measurement, the solution was put into the reaction vessel to start the polymerization, and the time until the polymerization was completed was measured.
<2. Water dispersion powder injection method>
In the water dispersion powder charging method, water and maleimide monomer (B) are brought into contact with each other in a predetermined dispersion tank different from the reaction tank to prepare a dispersion, and the dispersion is charged into the reaction tank. Then, polymerization was performed.
In the water dispersion powder charging method, the time from the contact of water and the maleimide monomer (B) in the dispersion tank to the completion of polymerization was measured.

(III. Aggregate generation amount, polymerization stability)
Aggregates remaining on the sieve when the polymerization reaction solution is passed through a 1.68 mm mesh sieve are collected, and the mass of the aggregates after drying at 85 ° C. for 12 hours is divided by the monomer weight used in the reaction. The aggregate generation rate (%) was calculated and used as an index of polymerization stability.
Evaluation was made with “◯” for less than 1.0%, “Δ” for 1.0% or more and less than 2%, and “x” for 2% or more.

(IV. Productivity evaluation)
Measured in the above <dissolution method> and <water-dispersed powder input method>, those having a polymerization time of more than 300 minutes have a poor productivity evaluation “x”, those having a polymerization time of 300 minutes or less have a good productivity evaluation “ "".

(V. Transparency; measurement of total light transmittance)
Based on the ISO 13468-1 standard, the total light transmittance was measured using a 3 mm-thick test piece, and used as an index of transparency.

(VI. Color tone; YI measurement)
<Evaluation of yellowness difference>
Test pieces having a thickness of 4 mm, a width of 40 mm, and a length of 60 mm were molded using the methacrylic resin particles produced in Examples and Comparative Examples described later.
After using the color difference meter 300A of Nippon Denshoku Industries Co., Ltd. for 192 hours in a constant temperature and humidity chamber set to the YI value (i) of the test piece and the set temperature 80 ° C. and set humidity 95% Rh The YI value (ii) was measured, and the degree of change in the YI value was measured.
When the difference between the above (ii) and the above (i) was 1 or more, the evaluation was made as “bad”: “x”, and “less”: less than 1: “◯”.

(VII. Moist heat resistance test)
Using a IS-100EN injection molding machine manufactured by Toshiba Machine Co., Ltd., a test piece having a thickness of 3 mm, a width of 100 mm and a length of 100 mm was produced at a molding temperature of 270 ° C. and a mold temperature of 60 ° C., and a temperature of 90 ° C. and a humidity of 95 The shape of the test piece after observing it for 500 hours in a constant temperature and humidity chamber set to% is observed. “X” indicates that the deformation such as distortion is observed, “△” indicates that the deformation is slightly observed, Evaluation was made as “◯” when almost no deformation was observed.

(VIII. Measurement of residual amine amount)
The amount of residual amine contained in the methacrylic resin was measured under the following conditions and equipment.
Measuring device: Agilent MSD5975C
Column used: DB-1 30 m × 0.25 mm i. d. Liquid phase thickness 0.25μm
Carrier gas: helium Split ratio: (1:10)
Column temperature: 40 ° C (5 min hold) ⇒ 20 ° C / min temperature rise ⇒ 320 ° C (11 min hold)
I / F temperature: 320 ° C
Inlet temperature: 320 ° C
Injection volume: 1.0 μL
i) Quantification of the amount of aniline A sample of 40 mg was measured at a constant volume of 2 mL using chloroform. Quantification was performed from a calibration curve prepared from an aniline standard solution.
ii) Determination of the amount of cyclohexylamine To 10 mg of a sample, 0.5 mL of N-methyl-bis (trifluoroacetamide) was added and reacted at room temperature for 2 hours, and then the volume was adjusted to 2 mL using methylene chloride and measured. . The cyclohexylamine standard solution was also quantified by preparing a calibration curve after derivatization in the same manner.
In Table 2 below, “residual amine amount” is the total amount of aniline and cyclohexylamine determined as described above.

Hereinafter, a method for producing a methacrylic resin will be described.
The blending amounts are shown in Table 1 below.
Table 2 below shows the monomer charge composition, the measurement results of the weight average molecular weight, and the polymerization conditions.

[Example 1]
2 kg of water, 65 g of tricalcium phosphate, 39 g of calcium carbonate, and 0.39 g of sodium lauryl sulfate were charged into a container having a stirrer equipped with four inclined paddle blades to obtain a mixed solution (a).
Separately, in a container (dispersion tank) that requires a stirrer equipped with four inclined paddle blades, the amount of N-phenylmaleimide shown in Table 1 below is added, and then 21 kg of ion-exchanged water at 50 ° C. is added and stirred for 10 minutes. Dispersion was performed to prepare a dispersion. The pH of the ion exchange water used was 6.1.
Next, the dispersion was transferred at a rate of 10 kg / min to a 60 L reactor (reaction tank) having a stirrer equipped with three receding blades. In order to wash away the N-phenylmaleimide remaining in the dispersion tank and the pipe, 5 kg of hot water at 50 ° C. was introduced into the dispersion tank and transferred again.
Subsequently, the mixed solution (a) was added, and further a raw material mixture other than N-phenylmaleimide was added in the amount shown in Table 1 below.
Thereafter, the temperature was raised to about 75 ° C. and suspension polymerization was carried out while maintaining the temperature at about 75 ° C., and an exothermic peak was observed about 125 minutes after the starting material mixture other than the N-phenylmaleimide was added.
Thereafter, the temperature was raised to about 93 ° C. at a rate of 1 ° C./min, and then a aging reaction was carried out at a temperature of 93 to 98 ° C. for 120 minutes to substantially complete the polymerization reaction. The time from the contact of water and the maleimide monomer (B) in the dispersion tank to the completion of the polymerization was 290 minutes.
Next, in order to cool to 50 ° C. and dissolve the suspending agent, 20 mass% sulfuric acid was added.
Next, the polymerization reaction solution is passed through a 1.68 mm mesh sieve to remove aggregates, the water is filtered off, the resulting slurry is dehydrated to obtain a bead polymer, and the resulting bead polymer is After washing with water, it was dehydrated in the same manner as described above, and further washed with ion-exchanged water and repeated dehydration to obtain polymer particles.
The obtained polymer particles were dried in a hot air drying oven at 85 ° C. for 12 hours, then melt-kneaded in a φ30 mm twin screw extruder set at a barrel temperature of 240 ° C., and the strands were cooled and cut to obtain resin pellets. . The extrusion workability at that time was good. Using the obtained pellets, an injection molded article was produced and evaluated as described above.

[Example 2]
Polymerization and evaluation were carried out in the same manner as in Example 1 except that the preparation of the dispersion of the maleimide monomer (B) and the transfer method were changed to the following methods.
That is, the dispersion is charged in a container (dispersion tank) that requires a stirrer equipped with four inclined paddle blades, and after adding N-phenylmaleimide in an amount shown in Table 1 below, 18 kg of 45 ° C. warm water is added. Prepared by stirring and dispersing for minutes.
Next, the dispersion was transferred at a rate of 10 kg / min to a 60 L reactor (reaction tank) having a stirrer equipped with three receding blades. In order to wash away the N-phenylmaleimide remaining in the dispersion tank and the pipe, 5 kg of ion exchange water at 50 ° C. was introduced into the dispersion tank and transferred again. Further, 3 kg of ion exchange water at 55 ° C. was added and transferred to the reaction vessel.
The evaluation results are shown in Table 2 below.

[Examples 3 to 10]
The monomer and its blending amount were changed as shown in Table 1.
Further, the supply temperature of the component (B) to the reaction tank, the number of post-washes, the post-wash water temperature, and the supply temperature of monomers other than the component (B) to the reaction tank were changed as shown in Table 2.
Polymerization was performed in the same manner as in Example 1 under other conditions. The evaluation results are shown in Table 2 below.

[Comparative Example 1]
2 kg of water, 65 g of tricalcium phosphate, 39 g of calcium carbonate, and 0.39 g of sodium lauryl sulfate were charged into a container having a stirrer equipped with four inclined paddle blades to obtain a mixed solution (a).
N-phenylmaleimide and other raw material mixtures were mixed and dissolved at 10 ° C. in the blending amounts shown in Table 1 below to obtain a solution (b).
It took 2 hours until the N-phenylmaleimide particles could hardly be visually confirmed.
Next, water (26 kg) was charged into a 60 L reactor (reaction tank) having a stirrer equipped with three retreating blades, the temperature was raised to 75 ° C., and then the mixed solution (a) was charged. (B) was charged.
Thereafter, suspension polymerization was carried out while maintaining the temperature at about 80 ° C., and an exothermic peak was observed about 120 minutes after the starting material mixture was added.
Thereafter, the temperature was raised to 93 ° C. at a rate of 1 ° C./min and then aged for 120 minutes to substantially complete the polymerization reaction.
After starting mixing to dissolve the maleimide monomer (B), the methacrylic acid ester monomer (A), and other vinyl monomers (C) as necessary, the reaction The time until the polymerization was completed after being charged into the tank was 365 minutes.
Next, in order to cool to 50 ° C. and dissolve the suspending agent, 20 mass% sulfuric acid was added.
Next, the polymerization reaction solution is passed through a 1.68 mm mesh sieve to remove aggregates, the water is filtered off, the resulting slurry is dehydrated to obtain a bead polymer, and the resulting bead polymer is After washing with water, it was dehydrated in the same manner as described above, and further washed with ion-exchanged water and repeated dehydration to obtain polymer particles.
The obtained polymer particles were dried in a hot air drying oven at 85 ° C. for 12 hours, then melt-kneaded in a φ30 mm twin screw extruder set at a barrel temperature of 240 ° C., and the strands were cooled and cut to obtain resin pellets. . The extrusion workability at that time was good. Using the obtained pellets, an injection molded article was produced and evaluated as described above.

[Comparative Example 2]
(B-2) was used as a maleimide monomer, and according to the compositions shown in Tables 1 and 2, polymerization was carried out under the same conditions as in Example 1 and the above evaluations were performed.

[Comparative Example 3]
N-phenylmaleimide and other raw material mixtures were mixed at 10 ° C. in the blending amounts shown in Table 1 below.
Stirring was performed for 3 hours, and dissolution was attempted. However, since a large amount of undissolved N-phenylmaleimide was observed, the mixture was heated to 50 ° C. and further stirred for 30 minutes, and N-phenylmaleimide particles could hardly be visually confirmed. Until dissolved to obtain a dissolved solution (dissolved solution (b)). The other conditions were the same as in Comparative Example 1, and the above evaluation was performed.

In Examples 1 to 10, it can be seen that, compared with the method of dissolving N-phenylmaleimide as in Comparative Example 1, it is possible to significantly shorten the production time while maintaining the polymerization stability. It was. The obtained methacrylic resin also had good characteristics.
Further, as in Examples 1 to 10, maleimide monomers (B-1: containing 0.5% by mass) and (B-3: containing 0.7% by mass) with less components of 0.15 mm or less are used. When compared with the case of using a maleimide monomer having many components of 0.15 mm or less as in Comparative Example 2 (B-2: containing 16% by mass), it is not supplied in a state dissolved in another monomer. Further, it was found that even when a method of supplying to a reaction vessel in a state of being dispersed in water can maintain high polymerization stability, it is excellent in color tone stability.
Looking at Comparative Example 3, when the amount of maleimide monomer is large, even if it is stirred for a long time, it does not completely dissolve in the raw material mixture, and it must be dissolved by heating, resulting in low productivity. Met.

  The methacrylic resin obtained by the production method of the present invention is used for household goods, OA equipment, AV equipment, battery electrical equipment, lighting equipment, housing use, sanitary use, elastic play equipment use, head lamp cover, rear lamp cover, rear combination lamp. Light guide plate, diffuser plate, polarizing plate protective film used for displays such as covers, visors, bug guards, instrument covers, meter panels and other vehicle parts, liquid crystal displays, plasma displays, organic EL displays, field emission displays, rear projection TVs, etc. , 1/4 wavelength plates, 1/2 wavelength plates, viewing angle control films, retardation films such as liquid crystal optical compensation films, display front plates, display substrates, lenses, touch panels, etc., and also used for solar cells Good for transparent bases It can be used for. In addition, in the fields of optical communication systems, optical switching systems, and optical measurement systems, as waveguides, lenses, optical fibers, optical fiber coating materials, LED lenses, lens covers, and other resin modifiers, There is a possibility of use.

Claims (11)

Methacrylic acid ester monomer (A): 50 to 99% by mass,
Maleimide monomer (B) 1-30% by mass,
And other vinyl monomer (C): having a polymerization step of copolymerizing 0 to 20% by mass in a reaction vessel,
A method for producing a methacrylic resin that satisfies the following conditions (1) to (3).
(1) The maleimide monomer (B) is solid at 25 ° C. (2) The maleimide monomer (B) is supplied to the reaction vessel in a state dispersed in water.
(3) In the maleimide monomer (B), the content of a particle size component of 0.15 mm or less is 10% by mass or less.   2. The methacrylic monomer according to claim 1, wherein the aqueous dispersion of the maleimide monomer (B) is supplied into the reaction vessel at a temperature that is 20 ° C. or more lower than the melting point of the maleimide monomer (B). Manufacturing method of resin. Polymerization monomers other than the maleimide monomer (B),
The method for producing a methacrylic resin according to claim 1 or 2, wherein the reaction vessel is supplied into the reaction vessel under a condition that the temperature is 20 ° C or more lower than the melting point of the maleimide monomer (B). .   The method for producing a methacrylic resin according to any one of claims 1 to 3, wherein the maleimide monomer (B) is at least one selected from the group consisting of N-phenylmaleimide and N-cyclohexylmaleimide. .   The method for producing a methacrylic resin according to any one of claims 1 to 4, wherein the polymerization step is performed by a suspension polymerization method.   The method for producing a methacrylic resin according to any one of claims 1 to 5, wherein a temperature of water in which the maleimide monomer (B) is dispersed is 0 ° C or higher and 80 ° C or lower.   The manufacturing method of the methacrylic resin as described in any one of Claims 1 thru | or 6 whose content of the particle diameter component of 9.5 mm or more of the said maleimide-type monomer (B) is 10 mass% or less.   The method for producing a methacrylic resin according to any one of claims 1 to 7, wherein an average particle diameter of the maleimide monomer (B) is 0.2 mm or more and 9 mm or less.   In the said superposition | polymerization process, a polymerization initiator is supplied to the said reaction tank with the said methacrylic ester monomer (A) and the said other vinyl monomer (C). A method for producing a methacrylic resin according to claim 1.   A methacrylic resin obtained by the method for producing a methacrylic resin according to any one of claims 1 to 9.   The molded object containing the methacrylic resin of Claim 10.