JPH06166714A - Production of methacrylic resin containing methacrylimide unit - Google Patents

Abstract

PURPOSE:To obtain the subject resin maintaining transparency, heat discoloration resistance, strength and processability, having high heat resistance by dissolving a resin mainly comprising methyl methacrylate unit, having a low dimer content in a mixed solvent and reacting with an amine. CONSTITUTION:A resin mainly comprising a methyl methacrylate unit as a main constituent unit, having <=1,000ppm dimer content is supplied from a pellet storage tank 8 to a resin dissolving tank 10, dissolved in a mixed solvent fed from a solvent storage tank 1, this solution is sent to an imidating tank 20, reacted with an imidating agent comprising an amine of the formula R<2>NH2 (R<1> is H, 1-20C aliphatic, alicyclic or aromatic hydrocarbon) fed from an imidating agent storage tank 18, the reaction product is sent through a discharge line 25, a pump 26 and a line 27 to a volatile substance separator 28. A volatile component is removed and the resulting substance is discharged from a polymer outlet 29 to give a methacrylic resin containing a methacrylimide unit of the formula.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a methacrylic resin containing a methacrylimide unit.

[0002]

2. Description of the Related Art Polymers composed of methacrylic acid esters such as methyl methacrylate (hereinafter referred to as methacrylic resin) are excellent in mechanical properties and weather resistance as well as transparency, and therefore have high performance. It is used as a plastic light-transmitting fiber, a decorative material, and the like. In recent years, the use of the light-transmitting fiber has been developed in the fields of short-distance optical communication and optical sensors. However, the methacrylic resin has insufficient heat resistance such that the heat deformation temperature of polymethylmethacrylate is around 100 ° C., so that there are many fields in which application development is restricted, and there is a strong demand for improvement in heat resistance.

As a means for improving the heat resistance of methacrylic resin, for example, a polymer made of methyl methacrylate is
Method of reacting with a primary amine (US Pat. No. 2,146,2)
No. 09, West German Patent No. 1,077,872, and No. 1,242,369) have been proposed.

Also, a method of reacting a polymer from a methacrylic acid ester with a water-soluble ammonium salt or an N-alkylammonium salt (US Pat. No. 3,244,679)
US Pat. No. 3,2), a method of reacting a polymer using a methacrylic acid ester with a primary amine in an aqueous system.
84,425) and the like have been proposed. Furthermore, a method of reacting a polymer from a methacrylic acid ester with ammonia or a primary amine using an extruder (US Pat. No. 4,246,374) has been proposed.

[0005]

However, the methacrylimide unit-containing methacryl resin obtained by the above method (hereinafter sometimes abbreviated as methacrylimide resin) has improved heat resistance, but is inferior in transparency. Or, since the molecular weight of the methacrylic resin is substantially reduced or the imidization is non-uniform, it is inferior in mechanical properties, optical properties, coloration and molding processability and cannot be put to practical use. Is the current situation. Especially in the field where a high degree of transparency is required, a methacrylimide resin that can be put to practical use could not be obtained.

For example, in the method described in US Pat. No. 2,146,209, a single solvent or no solvent is used in the imidization reaction. Therefore, according to this method, a methacrylimide resin having improved heat resistance can be obtained, but a methacrylimide resin excellent in transparency and coloration (heat resistant coloring) cannot be obtained.

US Pat. No. 4,246,374 shows the imidization of molten methacrylic resin with a gaseous low molecular weight imidizing agent such as ammonia, methylamine, etc. in an extruder. There is. However, in this method, a low-viscosity, that is, gaseous imidizing agent is added to the molten high-viscosity system, and imidization becomes nonuniform. Further, since an extruder is used, the time used for imidization is insufficient, and the molecular weight of the methacrylic resin is further reduced. If the imidization is not uniform and the imidization time is insufficient, a methacrylimide resin excellent in transparency and coloration cannot be obtained.

An object of the present invention is to provide a method for producing a methacrylimide resin which is excellent in heat resistance while maintaining the original excellent optical properties, chromatic properties, mechanical properties, weather resistance and moldability of methacrylic resin. To provide.

[0009]

[Means for Solving the Problems] That is, the present invention provides a resin containing a methyl methacrylate unit as a main constituent unit and having a methyl methacrylate dimer content of 1,000 ppm or less in a solvent mixture for the resin. Formula (I) when dissolved in

[0010]

Embedded image An amine represented by R ¹ NH ₂ (I) (wherein R ¹ is a hydrogen atom or an aliphatic, alicyclic or aromatic hydrocarbon group having 1 to 20 carbon atoms). The general formula (I
I)

[0011]

[Chemical 4] The present invention relates to a method for producing a methacrylimide unit-containing methacrylic resin represented by the formula (wherein R ¹ is as defined above).

In the present invention, the methacrylimide unit-containing methacryl resin means a polymer in which a methacrylimide segment is introduced into the polymer main chain of the methacryl resin.

The methacrylimide resin obtained by the method of the present invention has a yellowness (YIs) in a solution of a heating resin of 3 or less, preferably 0.1 to 1, and a yellowness (YIp) in a molded plate. It is 2.7 or less, preferably 0.2 to 1.5, and the total light transmittance is 89 to 95%, preferably 90 to 92%. Also, the intrinsic viscosity measured at 25 ° C. in dimethylformamide is in the range of about 0.01 dl / g to 3.0 dl / g.

The methyl methacrylate dimer as referred to in the present invention is a compound produced from two molecules of methyl methacrylate monomer, which is a by-product when producing a polymer having a methyl methacrylate unit as a main constituent unit. . The content of this methyl methacrylate dimer is 1000 ppm or less, preferably 25
Methacrylic resin of 0 ppm or less and the above general formula (I)
The methacrylimide unit-containing methacrylic resin obtained by reacting the amine represented by the formula (1) with the above-mentioned solvent mixture under specific conditions is excellent in transparency, especially in heat coloration.

When producing a methacrylimide unit-containing resin from a methacrylic resin, it is preferable that the imidization ratio is 45% or more from the viewpoint of generally improving the heat resistance of the resin, and the productivity is also taken into consideration. Then, the above general formula (I
The methacrylimide unit represented by I) is 45 to 98.5.
It is highly desirable to include wt%. However, in the method of the prior art, the yellowness (YIs) in the solution of the heating resin and the yellowness (YIp) in the molded plate are used for the resin having a methacrylimide unit content, that is, an imidization ratio exceeding 45%. No resin having a value of within the above range was obtained.

In a polymer containing a methyl methacrylate unit as a main constitutional unit, a dimer of methyl methacrylate is 1.0
When it is contained in excess of 00 ppm, this dimer reacts with an amine in the reaction step described later to form a coloring substance composed of a low molecular weight amide, and this coloring substance is a methacrylic acid in the step of separating a volatile substance. It is extremely difficult to separate it from the imide resin. Therefore, in order to produce a highly transparent and less colored methacrylimide resin, which is the object of the present invention, it is necessary to reduce the content of the methyl methacrylate dimer in the methacryl resin before reacting with the amine as much as possible. It's important.

In the method for producing a methacrylimide resin of the present invention, for example, 5 to 80 parts by weight of the methacrylic resin described above is added to a solvent mixture consisting of 19 to 94 parts by weight of an aromatic hydrocarbon and 1 to 76 parts by weight of an aliphatic alcohol. In a dissolved state (the total amount of the methacrylic resin and the solvent mixture is 100 parts by weight), the amine (one kind or more) may be added at a temperature of 100 ° C. or higher and lower than 350 ° C. and mixed with stirring. Then, volatile substances are separated from the obtained reaction product. Especially when the solvent mixture is not used, the methacrylimide resin having low yellowness as described above cannot be obtained.

The methacrylic resin used in the present invention generally has an intrinsic viscosity of 0.01 to 3.0 dl / g (25 ° C.,
Methylmethacrylate homopolymer which is measured in dimethylformamide), or methylmethacrylate and acrylic acid ester, other methacrylic acid ester, acrylic acid,
A copolymer with other copolymerizable monomers such as methacrylic acid and styrene. In this case, the amount of the other copolymerizable monomer used is preferably 75% by weight or less of the monomer mixture with methyl methacrylate. Acrylic acid esters include, for example, methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, benzyl acrylate, and methacrylic acid esters include ethyl methacrylate, butyl methacrylate, and methacrylic acid. Cyclohexyl, benzyl methacrylate and the like can be used. Two or more kinds of these monomers may be used in combination.

In the methacrylic resin used in the present invention, when other copolymerizable monomers such as those mentioned above are used in addition to methyl methacrylate, the methacrylimide resin obtained is usually represented by the above-mentioned general formula. In addition to the methacrylimide unit represented by (II), general formula (III)

[0020]

[Chemical 5] (In the formula, R ² is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a benzyl group or a cyclohexyl group, and R ³ is a hydrogen atom or a methyl group).
Methacrylic acid or ester units thereof and / or general formula (IV)

[0021]

[Chemical 6] It is preferable that the aromatic vinyl monomer unit represented by the formula (1) is contained, and the amount thereof is 90% by weight or less in the total amount of one or both of the general formula (III) and the general formula (IV).

In the method for producing a methacrylimide resin of the present invention, a step of separating volatile substances is involved after the above-mentioned reaction step. In the reaction step, methacrylic resin and the above general formula (I) are used.
Is a step of causing a condensation reaction between the side chains of the methacrylic resin by reacting with the amine represented by. The volatile substance separation step is a step of separating a volatile substance containing a solvent mixture as a main component from a reaction product containing the imidized methacrylic resin produced in the reaction step. In the reaction step, the amine represented by the general formula (I) is dissolved and reacted in a solution in which the methacrylic resin is dissolved in the solvent mixture.

The solvent does not inhibit the imidization reaction, which is a condensation reaction between polymer side chains, and, in the case of the partial imidization reaction, does not change the methyl methacrylate or methacrylate ester segment portion. It is necessary.

Examples of such a solvent include alcohols, especially methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol,
Examples include a mixture of aliphatic alcohols such as isobutyl alcohol, aromatic hydrocarbons such as benzene, toluene and xylene, ketones such as methyl ethyl ketone, tetrahydrofuran and dioxane, and ether compounds. Mixtures of benzene, toluene or xylene with methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol and the like are preferable.

In order to obtain a methacrylimide resin having excellent transparency, it is preferable to use these solvents after filtering and purifying with a porous membrane.

A small amount of the solvent mixture is preferable from the viewpoint of production, but if it is too small, the effect of the solvent mixture is lowered, so that the polymer concentration is 5 to 80% by weight, preferably 20 to 80% by weight. The range is good.

Excellent transparency, yellowness (YIs, YIp)
In order to obtain a methacrylimide resin having a low content, it is necessary to carry out the imidization reaction in the presence of a solvent that dissolves the raw material methacrylic resin, the amine represented by the general formula (I), and the methacrylimide resin formed. When the imidization reaction is carried out in an insoluble state or in the absence of a solvent, a part of the raw material methacrylic resin is imidized, and the other remaining part is not imidized, that is, as a mixture of the raw material methacrylic resin and the methacrylimide resin. Obtained,
A resin with excellent transparency cannot be obtained.

Further, when only a solvent in which only the raw material methacrylic resin is easily dissolved, for example, aromatic hydrocarbons such as benzene, toluene and xylene, is used, the methacrylimide resin as a product is not dissolved and high imidization is achieved. It is not possible to uniformly obtain a methacrylimide resin having a specific ratio. Methanol, which is a poor solvent for the raw material methacrylic resin,
Alternatively, when only an aliphatic alcohol, which is not as good as an aromatic hydrocarbon, is used as a solvent, not only the imidization reaction does not proceed in a uniform state, but also the imidization reaction does not complete, so that the yellowness is high and it is colored. A methacrylimide resin is produced.

On the other hand, the use of a solvent mixture prepared by mixing at least two kinds of solvents as described above solves the above problems and makes it possible to obtain a desired methacrylimide resin having excellent transparency and coloration.

Among the amines represented by the general formula (I) used in the production method of the present invention, examples of amines in which R ¹ is an aliphatic hydrocarbon group include methylamine, ethylamine, propylamine and the like. It is also possible to use compounds such as 1,3-dimethylurea, 1,3-diethylurea, 1,3-dipropylurea which generate these amines upon heating, ammonia and urea.

Examples of amines in which R ¹ is an aromatic hydrocarbon group include aniline, toluidine, trichloroaniline and the like. Examples of the amine in which R ¹ is an alicyclic hydrocarbon group include cyclohexylamine and the like.

The amount of these compounds used is determined by the formula (I
At least 10 methacrylimide units represented by I)
Although the content is such that it is contained by weight%, it can be used, for example, in the range of 0.05 to 20 mol per mol of the methyl methacrylate monomer unit of the methacrylic resin.

The reaction between the methacrylic resin and the amine in the reactor is 100 ° C or higher and 350 ° C or lower, preferably 150 ° C.
It can be performed at a temperature of not less than 0 ° C and not more than 300 ° C. If the reaction temperature is lower than 100 ° C, the imidization reaction is slow, and if it exceeds 350 ° C, the decomposition reaction of the raw material methacrylic resin occurs simultaneously. The reaction time is not particularly limited and is preferably short from the viewpoint of productivity, but is preferably 30 minutes to 5 hours. The reaction pressure is determined according to the type of amine used, the reaction temperature, and the imidization ratio.

The reactor used in the method for producing the methacrylimide resin of the present invention may be any one as long as it does not impair the object of the present invention, but the imidization is carried out uniformly and a uniform methacrylimide unit is used. In order to obtain the contained polymer, it is preferable to use a tank-type reactor equipped with a supply port, a discharge port and a stirring device and having a mixing function in the entire reactor.

In the step of separating the volatile substance, most of the volatile substance is separated and removed from the reaction product of the methacrylic resin and the imidizing agent. The content of the residual volatile substance in the obtained methacrylimide resin is finally 1% by weight or less, preferably 0.1% by weight or less. Removal of volatile substances
Use a general vent extruder, depolizer, etc., or use another method, for example, a method in which the reaction product is diluted with a solvent, precipitated and filtered in a large amount of insoluble medium, and then dried. You can

In the production method of the present invention, it is preferable to add a small amount of an antioxidant in order to prevent a decrease in molecular weight due to radical depolymerization of the methacrylic resin as a raw material under a high temperature reaction. As used herein, antioxidants include tricresyl phosphite, cresyl phenyl phosphite, trioctyl phosphite, phosphite-based phosphite antioxidants such as tributoxyethyl phosphite, hydroquinone, cresol. Specific examples thereof include hindered phenol antioxidants of phenol derivatives, naphthylamine, phenylenediamine, amine antioxidants of hydroquinoline derivatives, and alkyl mercaptans and dialkyl sulfide derivatives.

Further, other additives such as a plasticizer, a lubricant, an ultraviolet absorber, a colorant and a pigment may be added and used depending on the requirements of the performance of the product.

A typical apparatus used in the process for preparing the methacrylimide resin of the present invention will now be described with reference to FIG. 1: An inert solvent mixture is passed from solvent reservoir 1 through line 2 and pump 3 into solvent. The antioxidant that is sent to the supply tank 4 and added as necessary is supplied from the antioxidant storage tank 5 to the line 6
After that, it is supplied to the solvent supply tank 4 and dissolved therein, and then sent to the resin dissolution tank 10. On the other hand, the resin is supplied from the pellet storage tank 8 to the resin dissolution tank 10 via the line 9. Resin dissolution tank 10
Is equipped with a stirrer 11 and a jacket 12 in which a heat medium flows through openings 13 and 14. Dissolved resin in the resin dissolution tank 10 is discharged line 15, pump 1
6, sent to the reaction tank 20 via the line 17, and reacted in the reaction tank 20 with the imidizing agent supplied from the imidizing agent storage tank 18 via the line 19. The reaction tank 20 includes a spiral ribbon stirrer 21 and a jacket 22, and a heat medium flows through the openings 23 and 24 in the jacket. The reaction product in the reaction tank 20 is discharged through the discharge line 25,
It is sent to a volatile substance separator 28 through a pump 26 and a line 27, where volatile components are removed, and a polymer outlet 29
Emitted from. Volatile substance separator 28 is screw 3
0, vent 31, and means 32 for heating.

[0039]

EXAMPLES The present invention will be described in more detail below with reference to examples and examples. Parts and% used in the following description are parts by weight and% by weight, unless otherwise specified, except for the total light transmittance. The apparatus system of FIG. 1 has the following specifications: Resin dissolution tank 500 liters Reaction tank 40 liters Volatile substance separation device Single screw vent type extruder Screw: 30 mm φ × 720 mm length Vent length: 60 mm In the examples The method for measuring the characteristics of the raw material polymer and the produced resin was as follows. (1) The infrared absorption spectrum was measured by the KBr disk method using an infrared spectrophotometer (Model 285, manufactured by Hitachi, Ltd.): (2) The intrinsic viscosity of the polymer was measured by Dero Bishop (Dee).
The flow time (ts) of a dimethylformamide solution having a sample polymer concentration of 0.5% by weight and the flow time (t) of dimethylformamide were measured by a relax-Bischoff viscometer.
o) was measured at a temperature of 25 ± 0.1 ° C., and the relative viscosity η _{rel of the} polymer was determined from the ts / to value, and then calculated from the following equation: Intrinsic viscosity = (ln η _rel / C) c → o (In the formula, C represents the number of grams of the polymer per 100 ml of the solvent.) (3) The heat distortion temperature was measured based on ASTM D648. (4) The melt index of the polymer is ASTM D1.
238 (230 ° C., grams for 10 minutes at a load of 3.8 kg). (5) The imidization ratio (%) of the polymer was measured by an elemental analysis value (measuring machine CNH coder (MT-3), manufactured by Yanagimoto Seisakusho).
Content of Nitrogen and Proton NMR JNM-FX-10
0 (JEOL) spectrometer 100 MHz, and the ratio of the imide ring unit to the total amount of the imide ring unit and the monomer unit constituting the methacrylic resin is shown in% (in the table, mol% is shown. Exist). (6) Transparency was measured according to ASTM D-1003-61 after heat-press molding the obtained resin to a thickness of 2 mm. (7) Yellowness (YIs) of solution of heated resin is JIS-K-
7103 was measured. That is, the obtained pellets of methacrylimide resin were heated and kept at 150 ° C. for 15 days in an air atmosphere, then made into a 15% by weight methylene chloride solution, and the degree of yellowness (YIs) measured by transmitted light was measured by the above method, and the pellet was heated. The degree of yellowness was set. YIs was calculated by the following formula: X, Y, Z: Tristimulus value of test sample or test piece under standard light In addition, the molded plate obtained in (6) was used and heated at 150 ° C. for 15 days in the same manner as above, and then molded. The coloration of the plate due to heating was visually evaluated: Almost no change ○ Slightly yellowish color △ Yellowish color × (8) Yellowness (YIp) in the molded plate was 5 ounce injection molded from the obtained polymer pellets. Machine (Meiki Co., Ltd., SA
V-30) after flat plate molding to a thickness of 2 mm and 80 x 80 mm,
It was measured by the transmitted light of a flat plate: Molding conditions Cylinder temperature 290 ° C. Molding cycle 60 seconds YIp was calculated by the following formula: X, Y, Z: Tristimulus value of test sample or test piece under standard light (9) Method for measuring methyl methacrylate dimer A methacrylic resin containing methyl methacrylate as a main component is dissolved in an acetone solvent for gas chromatography. It was measured by the graphic method. The measurement column temperature was 150 ° C.

Reference Example Method for Preparing Methacrylic Resin Containing Methyl Methacrylate Dimer: A typical apparatus used for producing various methyl methacrylate polymers will be described with reference to FIG.

100 parts of methyl methacrylate monomer, 0.0-di-tert-butyl peroxide as a polymerization initiator
A mixture of 017 parts, dodecyl mercaptan 0.25 part, and in some cases 0 to 50 parts of non-polymerizable solvent (for example, toluene) was charged into the storage tank 40 through the line 41 through the pump 41 and 3 kg / hour from the pump 42 (display of monomer content). Was supplied to the polymerization reaction tank 43 at a flow rate of. At this time, if necessary, additives such as antioxidants were supplied from the additive storage tank 44 to the reaction tank 43 via the line 45. The reaction tank 43 was equipped with a spiral ribbon stirrer 46 and a jacket 47, and the heat medium was circulated through the openings 48 and 49 in the jacket.
This reaction vessel had an internal volume of 25 liters and was variable in the range of the polymerization reaction temperature of 60 ° C to 190 ° C. The polymerization conversion rate at this time was variable in the range of 40% to 70%. The methyl methacrylate polymer syrup produced in the polymerization reaction tank 43 passes through a line 50, a pump 51 and a line 52,
It was heated to 200 to 240 ° C. through the syrup heater 53. The syrup is then sent via line 54 to a volatiles separator 55 where volatiles such as unreacted methyl methacrylate monomer, and in some cases non-polymerizable solvents such as toluene and methyl methacrylate dimer are included. The temperature of the vent part was 190 to 250 ° C., and the degree of vacuum was 3 to 500 mmHg. The methyl methacrylate dimer here is produced as a side reaction in the polymerization reaction tank 43, the syrup heater 53, or the like. The produced methyl methacrylate polymer is obtained in a strand form from the polymer outlet 59, and is processed into a pellet form by a cutting machine or the like. Volatile substance separator 55 is screw 5
6, a vent 57 and means 58 for heating.

The volatile substance separating apparatus used herein has the following specifications: Single screw screw vent type extruder Screw: 30 mmφ, 720 mm length Vent length: 60 mm The methacrylic resin thus obtained contains methacrylic acid. Although the methyl dimer is contained, this amount is variable depending on the polymerization conditions (for example, the amount of solvent used, the polymerization temperature, the reaction conversion rate, etc.), the syrup heating temperature, and the ability to separate volatile substances. The content of the methyl methacrylate dimer in the following Examples and Comparative Examples uses the analytical value.

Example 1 10 fully dried methyl methacrylate polymer (methyl methacrylate dimer 30 ppm, intrinsic viscosity 0.51 dl / g) 10
Toluene 90 was produced by dehydrating and drying 0 part of the product, and filtering and purifying with 0.1 μm fluoropore (Sumitomo Electric Industries, Ltd.).
Parts, dehydrated and dried, and then placed in a 500 liter dissolution tank together with 10 parts of methanol filtered and purified with 0.1 μm fluoropore, and the polymer was dissolved under stirring at 200 ° C.

Next, this solution was continuously supplied to the reaction tank at a supply rate of 5 kg / hour (indicated by resin content), and the temperature in the tank was set to 230 while the mixing speed was 90 rpm and sufficient mixing was performed.
The temperature was adjusted to ° C. After that, dry methylamine was added to 0.1 μm.
After filtration and purification with fluoropore, it was continuously fed into the reaction vessel at a rate of 20 mol / hour to adjust the internal pressure to 45 kg / cm ² (gauge pressure). The temperature in the reaction tank was maintained at 230 ° C. during the reaction, and the average residence time was 4.5 hours. The reaction product taken out of this reaction tank was put into a 20 liter aging tank (not shown in FIG. 1) by a pump, and the average residence time was 2.0 hours and the aging tank temperature was 230 ° C. Aged under stirring. The aged reactant was continuously fed to the vent extruder to separate volatiles. The temperature of the vent extruder was 230 ° C. in the vent section, 230 ° C. in the extrusion section, and the degree of vacuum in the vent section was 9 mmHg abs'.

The strand extruded from the die was cooled with water and then cut to obtain a pellet-shaped resin composition having good transparency.

On the other hand, toluene, methanol and unreacted amine discharged from the vent were cooled and recovered. When the infrared absorption spectrum of the resin composition thus obtained was measured, absorptions peculiar to the methylmethacrylimide polymer were observed at wave numbers of 1720 cm ^-1 , 1663 cm ^-1 and 750 cm ^-1 .

The nuclear magnetic resonance spectrum showed a signal showing this structure. 8.3 in elemental analysis
It showed a nitrogen content of 100% (imidization amount of 100%), and was confirmed to be almost completely an N-methylmethacrylimide polymer. In addition, when the physical properties of the obtained resin were evaluated, the following properties were exhibited: Intrinsic viscosity 0.48 Melt index 1.5 Heat distortion temperature 175 ° C. Refractive index n _D (25 ° C.) 1.530 (Abbe 5 ounce injection molding machine (Meiki Seisakusho S Co., Ltd.) using the obtained pellet resin
AV-30) was used to mold a 2 mm-thick 80 × 80 mm flat plate, and the transparency was measured: Total light transmittance 91% Parallel light transmittance 90% Haze value 1.0% Using the obtained pellet-shaped resin Yellowness (YIs) was measured after heating at 150 ° C. for 15 days under air atmosphere. The following initial value YI is the value when the obtained pellet-shaped resin was measured in the same manner with a 15 wt% methylene chloride solution without heating: initial value YI = 0.15 after heating YIs = 0.4. YIp = 0.6 of molded plate Heated coloring degree of molded plate By the above measurement, it is understood that the methacrylimide resin of this example has good transparency and little change with heating.

Examples 2 to 23 Various methacrylimide resins were produced in the same manner as in Example 1 using the methacrylic resins and amines shown in Tables 1 and 2.

The internal pressure of the reaction tank was 20 to 80 kg / cm ² gauge pressure. Tables 1 and 2 show the reaction conditions and the evaluation results of the characteristics of the obtained resin.

[0050]

[Table 1]

[0051]

[Table 2] * 1 Methyl methacrylate polymer (intrinsic viscosity = 0.5
6) * 2 Methyl methacrylate-methacrylic acid copolymer (weight ratio = 95/5, intrinsic viscosity = 0.7) * 3 Methyl methacrylate-methyl acrylate copolymer (weight ratio = 95/5, intrinsic viscosity) = 0.35) * 4 Methyl methacrylate-acrylic acid copolymer (weight ratio = 95/5, intrinsic viscosity = 0.6) * 5 Methyl methacrylate-butyl acrylate copolymer (weight ratio = 90/10 , Intrinsic viscosity = 1.0) * 6 Methyl methacrylate-butyl methacrylate-methacrylic acid copolymer (weight ratio = 90/5/5, intrinsic viscosity = 0.65) * 7 Methyl methacrylate-acrylic acid tert- Butyl-tert-butyl methacrylate copolymer (weight ratio = 90 /
5/5, intrinsic viscosity = 1.05) * 8 Methyl methacrylate-tert-butyl acrylate copolymer (weight ratio = 95/5, intrinsic viscosity = 0.55) * 9 Methyl methacrylate-cyclohexyl methacrylate copolymer Polymer (weight ratio = 90/10, intrinsic viscosity = 0.
6) * 10 Those used in Example 1 Examples 24 to 28 Various methacrylimide resins were produced in the same manner as in Example 1 using the methacrylic resins, amines and solvents shown in Table 3.

The internal pressure of the reaction vessel was 40 to 80 kg / cm ² gauge pressure, and the solvent was purified in the same manner as in Example 1. Table 3 shows the reaction conditions and the evaluation results of the characteristics of the obtained resin.

[0053]

[Table 3] Comparative Examples 1 to 6 The same method as in Example 1 was repeated except that the content of the methyl methacrylate dimer in the methacrylic resin and the solvent were as shown in Table 4. Table 4 shows the measurement results of the characteristic values of the obtained methacrylimide resin. When the amount of methyl methacrylate dimer was large and when a single solvent was used, the degree of coloring of the resin by heating was remarkable.

[0054]

[Table 4]

[0055]

EFFECTS OF THE INVENTION According to the production method of the present invention, a methacrylimide resin which can easily control the imidization reaction and is excellent in quality can be industrially advantageously produced. In addition, the obtained methacrylimide resin is excellent in transparency, heat resistance, and heat tint resistance, so that it is required in such fields as CR.
T-filters, TV filters, fluorescent tube filters, liquid crystal filters, meters, or displays related to digital display boards, lighting optics, automobile headlight covers, electrical parts, optical fiber core materials, etc. It can be used and has extremely high industrial value.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a reaction device used in a method for producing a methacrylimide resin of the present invention.

FIG. 2 is a schematic explanatory view of an apparatus for producing a methacrylic resin.

[Explanation of symbols]

 1 solvent storage tank 8 pellet storage tank 10 resin dissolution tank 18 imidizing agent storage tank 20 imidization reaction tank 28 volatile substance separator 40 methyl methacrylate monomer storage tank 43 methyl methacrylate polymerization reaction tank 44 additive storage tank 53 syrup heating machine 55 Volatile substance separator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koji Nishida 20-1 Miyuki-cho, Otake-shi, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. (72) Inventor Masaru Morimoto 20-1 Miyuki-cho, Otake-shi, Hiroshima Mitsubishi Rayon Within the corporation

Claims (5)

[Claims] 1. A methyl methacrylate unit as a main constituent unit, and a methyl methacrylate dimer content of 1,0.
A resin having a concentration of 00 ppm or less is dissolved in a solvent mixture for the resin to give a compound of the general formula (I): R ¹ NH ₂ (I) (wherein R ¹ is a hydrogen atom or a carbon atom having 1 to 1 carbon atoms). A general formula (I) characterized by reacting with an amine represented by 20 aliphatic, alicyclic or aromatic hydrocarbon groups.
I) [Chemical 2] (In the formula, R ¹ is as defined above) A method for producing a methacrylic resin containing a methacrylimide unit. 2. The method for producing a methacrylic resin containing a methacrylimide unit according to claim 1, wherein the content of the methyl methacrylate dimer is 250 ppm or less. 3. The method for producing a methacrylic resin containing a methacrylimide unit according to claim 1, wherein the solvent mixture is a mixture of at least one of benzene, toluene and xylene and an aliphatic alcohol. 4. 5 to 80 parts by weight of a resin containing the above-mentioned methyl methacrylate unit as a main constituent unit, 19 to 94 parts by weight of at least one kind of benzene, toluene and xylene, and 1 to 76 parts by weight of an aliphatic alcohol. The method for producing a methacrylic resin containing methacrylimide units according to claim 1, 2 or 3, wherein a mixture consisting of 100 parts by weight is reacted with the amine. 5. The aliphatic alcohol is methyl alcohol,
The method for producing a methacrylic resin containing a methacrylimide unit according to claim 3 or 4, which is ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol or isobutyl alcohol.