JPS62156115A - Heat-resistant resin, production thereof and optical element composed therewith - Google Patents

Abstract

PURPOSE:To obtain the titled resin having excellent transparency and heat- resistance by coplymerizing methyl methacrylate and a specific N-substituted maleimide. CONSTITUTION:The objective heat-resistant resin is a copolymer of (A) 70-99(wt)% methyl methacrylate and (B) 1-30% N-cyclohexylmaleimide and/or N-t-butylmaleimide. The intrinsic viscosity of the copolymer is 0.3-1.0dl/g (measured in chloroform at 25 deg.C), the amount of residual methyl methacrylate in the copolymer is <=1.0% and the amount of residual N-t-butylmaleimide is <=0.3%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat-resistant resin, a method for producing the same, and an optical element. More specifically, it relates to a methacrylic copolymer resin with excellent transparency and heat resistance, such as a copolymer made of methyl methacrylate and a specific N-substituted maleimide, a method for producing the same, and an optical element made of the same resin. .

[Conventional technology]

Methyl methacrylate-based methacrylic resin has excellent optical properties and weather resistance, as well as mechanical properties and
It has relatively well-balanced performance in terms of thermal properties and moldability, so these properties can be used to create products such as signboards, lighting covers, nameplates, automobile parts, electrical equipment parts, decorations, and miscellaneous goods. It is widely used in many fields, and further applications are being developed.

However, the heat deformation temperature of the negative side is around 100°C, which means that the heat resistance is not sufficient, which limits its application in many fields, and there is a deep-rooted demand for improved heat resistance.

Many proposals have already been made regarding methods for improving the heat resistance of methacrylic resins. For example, a method of copolymerizing methyl methacrylate and α-methylstyrene, a method of copolymerizing methyl methacrylate, α-methylstyrene, and maleic anhydride (Japanese Patent Publication No. 49-10156
No.), a method for copolymerizing methyl methacrylate, α-methylstyrene and maleimide, a method of copolymerizing methyl methacrylate and methacrylic acid in the presence of a crosslinked polymer using a polyfunctional monomer. A method of copolymerizing, a method of copolymerizing methyl methacrylate, α-methylstyrene, and acrylonitrile, etc. have been proposed. However, although the above proposed method improves heat resistance to some extent, the polymerization rate is extremely low, resulting in extremely low productivity, poor mechanical properties, weather resistance, and optical properties, and molded products still exhibit significant coloration. At present, many problems remain in practical application, such as poor molding processability due to the narrow molding area.

Also, methyl methacrylate and N-aryl maleimir
A method of copolymerizing methacrylic wax (Japanese Patent Publication No. 43-9753) has also been proposed, but the resin obtained by this method loses the excellent mechanical properties and weather resistance that methacrylic wax originally has, and is still , due to the different copolymerizability of the monomers, there is a large amount of residual monomer, resulting in poor moldability and poor appearance.
Only colored products are obtained. Furthermore, depending on the polymerization method, the original transparency of the methacrylic resin may be significantly impaired.

In the end, all of the previously proposed methods lack practicality,
Particularly in the case of optical applications, the current situation is that it has not yet been adopted.

[Problem that the invention seeks to solve]

The object of the present invention is to develop an acrylic resin that not only has excellent optical properties, mechanical properties, weather resistance, and moldability comparable to polymethyl methacrylate resin, but also has excellent heat resistance and productivity. The present invention provides a resin, a method for producing the resin, and an optical element made of the resin.

[Means for solving problems]

The heat-resistant resin according to the present invention is methyl methacrylate 99
A copolymer consisting of ~70% by weight and 1-30% by weight of N-cyclohexylmaleimide and/or N-t-butylmaleimide, having an intrinsic viscosity of 0.3-1.0 d4/ as measured in chloroform at 25°C. g, and the amount of residual methyl methacrylate in the copolymer is 1.0% by weight or less, and the total amount of residual N-cyclohexylmaleimide and/or N-t-butylmaleimide is 0.3% by weight or less. shall be.

The method for producing a heat-resistant resin as described above includes 99 to 70% by weight of methyl methacrylate and 1 to 30% of N-cyclohexylmaleimide and/or Nt-butylmaleimide.
The monomer mixture consisting of the following (A) and (B) weight%
It is characterized by carrying out suspension polymerization in the presence of the three components (B) and (C), or the two components (B) and (C).

(A) (,) Acrylic acid alkyl ester and/or methacrylic acid alkyl ester having an alkyl group having 1 to 12 carbon atoms (I) 0 to 60 gb lithium, sodium, potassium acrylic acid and/or methacrylic acid and an acrylic acid and/or methacrylic acid salt (II) selected from the group consisting of ammonium salts.
(B) (a) an acrylic acid alkyl ester having an alkyl group having 1 to 12 carbon atoms;
or methacrylic acid alkyl ester (■) 0 to 60 weight ratio; and (c) at least one acrylic acid and/or methacrylic acid selected from the group consisting of lithium, sodium, potassium, and ammonium salts of acrylic acid and/or methacrylic acid. Acid salt (■) 0 to 20 weight and (c) general formula, where R, R', R"=H or CH3, 〒H3 X=-O-, -book- or -N-1 M=H , Li, Na, K or NI (4, n=
A water-soluble polymer obtained by combining an acrylic acid derivative or a methacrylic acid visiting conductor (I [I) represented by an integer of 1 to 3 with a weight ratio of 100 to 20, (C) an electrolyte having a -valent cation.

In the heat-resistant copolymer resin of the present invention, in order to maintain the excellent mechanical properties and weather resistance of the methacrylic resin,
It is necessary that the methyl methacrylate units it in the copolymer be present in a predominant amount relative to the amount of N-cyclohexylmaleimide and/or Nt-butylmaleimide units.

Also, N-cyclohexylmaleimide and/or N
- t-butylmaleimide is dissolved in the monomer mixture,
In order to stabilize the polymerization, a monomer mixture consisting of 99 to 70% by weight of methyl methacrylate and 1 to 30% by weight of N-cyclohexylmaleimide and/or N-t-butylmaleimide is copolymerized. It is necessary. If the amount of methyl methacrylate exceeds 99% by weight, the effect of improving heat resistance will be small. Note that methyl methacrylate and N-
It is also possible to copolymerize a small proportion of a monomer copolymerizable with cyclohexylmaleimide and/or Nt-butylmaleimide.

The heat-resistant copolymer resin of the present invention must have an intrinsic viscosity value of 0.3 to 1 dt/9 when measured in chloroform at 25°C in order to obtain desirable fluidity as a molding material. , a range of 0.4 to 0.7 dt/g is preferred. In particular, to obtain injection molded products with little distortion and good appearance for optical applications, a range of 0.35 to 0.60 dt/17 is optimal, and in the case of extrusion molding, 0.60
It is desirable to be in the range of ~0.80 dl/F.

In order for the heat-resistant copolymer resin of the present invention to have an excellent appearance with little coloring, it is generally necessary that the amount of residual monomer in the copolymer is 1.5% by weight or less, preferably 1% by weight. .0% by weight or less. More details L< words, tba,
Residual N-cyclohexylmaleimide and N-t-butylmaleimide are particularly likely to cause coloring and should be kept at 0.3% by weight or less, preferably 0.2% by weight or less. be. Residual methyl methacrylate is the main cause of deterioration of the appearance due to volatilization during heat processing such as silver and foaming, and should be at least 1.0% by weight or less, preferably at most 0.9% by weight.

In the present invention, by using a specific N-substituted maleimide, a heat-resistant resin with less coloring and excellent optical properties is made. A specific N-substituted maleimide is N
-t-butylmaleimide and N-cyclohexylmaleimide.

When N-methylmaleimide or N-ethylmaleimide, which is an N-alkylmaleimide with a smaller number of carbon atoms, is used, the heat resistance can be higher than that of the present invention, but the water absorption is large, and the optical element obtained therefrom is Dimensional accuracy tends to decrease. On the other hand, when an N-alkylamide having a larger number of carbon atoms is used, it tends to cause a decrease in copolymerizability, a decrease in the effect of improving heat resistance, and a decrease in fluidity. In addition, N-cycloalkylmaleimides other than N-cyclohexylmaleimide are not suitable; for example, when N-cyclopentylmaleimide or N-cyclooctylmaleimide is used, by-product particles generally increase, which tends to cause discoloration. .

Copolymers of methyl methacrylate and N-cyclohexylmaleimide and/or Nt-butylmaleimide can be produced in principle by bulk, solution emulsion or suspension polymerization. However, it is the object of the present invention. Particularly comparable to polymethyl methacrylate resin. In order to produce a resin having excellent optical properties with stable productivity (p-<), it is desirable to produce it by suspension polymerization.

Wave polymerization requires special reactors and devolatilizers, and reaction control is complicated. Solution polymerization has the same drawbacks as bulk polymerization and is inferior in productivity compared to bulk polymerization. The sheet polymerization method, in which a monomer mixture or a partially polymerized mixture is injected into opposing cells and polymerized, is also a type of bulk polymerization method, but it has low productivity and requires crushing and recycling in order to use it as a molding material. It is not adopted because it requires a process such as shaping.

Emulsion and suspension polymerization are more advantageous than the above methods in controlling equipment and polymerization conditions. However, emulsion polymerization requires a large amount of emulsifier to emulsify the monomer mixture, and as a result, the copolymer produces dust and is inferior in transparency compared to suspension polymerization. In addition, there are problems with the stability of the polymerization system, and depending on the composition, polymerization often occurs during the reaction. Therefore, the heat-resistant copolymer resin of the present invention is preferably produced by suspension polymerization.

During polymerization, the reaction system is stably dispersed and the particle size is uniform. Making rimmer beads is particularly important on an industrial scale. It is equally important that the copolymer is not colored or contaminated by the compound used. For this purpose, it is important to carry out suspension polymerization in the presence of the following three components (4), (B) and (C), or two components (B) and (c).

(A) (a) 0 to 60% by weight of an acrylic acid alkyl ester and/or methacrylic ester (■) having an alkyl group having 1 to 12 carbon atoms, and lithium, sodium, potassium and acrylic acid and/or methacrylic acid and Salt of acrylic acid and/or methacrylic acid selected from the group consisting of ammonium salts (n) 100~
Water-soluble polymer obtained by polymerizing 40% by weight, (B) (,) Acrylic acid alkyl ester and/or methacrylic acid ester having an alkyl group having 1 to 12 carbon atoms (I) 0 to 60 (b) lithium, sodium acrylic acid and/or methacrylic acid;
At least one type of acrylic acid and/or methacrylic acid selected from the group consisting of potassium and ammonium salts (■) 0 to 20% by weight and (C) general formula, where RtR'#R'=H or CH ,, CH3 X=-0-, -NH- or -N-1 M=HtLi, Na, ni'Bj or NH4, n=1
A water-soluble polymer obtained by combining 100 to 20% by weight of an acrylic acid derivative or methacrylic acid derivative represented by an integer of 3 to 3. (C) An electrolyte having a -valent cation.

Examples of the acrylic acid or methacrylic acid derivative (2) represented by the general formula (1), which is one component constituting the water-soluble polymer (B), include sodium salt of 2-sulfoethyl methacrylate, methacrylic acid Examples include the sodium salt of 2-sulfoglovir and the potassium salt of 2-acrylamido-2-methylpropanesulfonic acid.

Examples of the electrolyte (C) having a -valent cation include lithium, sodium, potassium, and ammonium salts of inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid; lower carbon atoms having 1 to 4 carbon atoms; lithium, sodium,
Potassium and ammonium salts; and lithium, sodium, potassium and ammonium salts of aliphatic and aromatic sulfonic acids.

The ratios of the above (6), (B), and (C) are: ■ O to iz parts by weight, ■
) 0.002 to 1.0 parts by weight, (C) 0.05 to 10
Parts by weight are preferred. Although the stability of the reaction system can be maintained even if (b) is not used in combination, it is preferable to use it in combination in order to reduce the amount of polymer adhering to the wall and giant particles and to make the particle size uniform. A more preferable usage ratio of (B) is 0.003 to 1.0 parts by weight; if it is less than 0.001 parts by weight, the dispersion effect will be insufficient, and if the amount exceeds 1 part by weight, the suspension polymerization itself will be inhibited. Although this can be done smoothly, the diversification effect does not increase much and it is not economically advisable. (C)
A more preferable proportion is in the range of 0.1 to 5 parts by weight,
If the amount of this electrolyte added is too small, it will become an undesirable amorphous powder in addition to the normal spherical particles). IJ Mama
The amount of derivation increases, and conversely, if the amount is too large, the particle size tends to become too large, which eventually leads to solidification.

Among other known suspension methods, for example, a method in which polymerization is carried out using an alkaline dispersion system with - of the reaction system exceeding 8 can not be adopted because the dispersion system becomes unstable as the reaction progresses and tends to solidify. Systems using CMC (carboxymethyl cellulose) have poor dispersibility, and when POVAL is used, it tends to solidify, and cloudiness remains in the copolymer, resulting in optically inferior products.

Another effective suspension polymerization method is to polymerize a poorly soluble material (for example, calcium hydrogen phosphate, tertiary calcium phosphate, etc.) with an anionic surfactant as a dispersant, but the stability of the dispersion system is limited. It may be bad depending on the mass composition,
Furthermore, the nine copolymers, which require acid washing, have the disadvantage that it is difficult to avoid staining and coloring caused by dispersants.

In the method of the present invention, suspension using a dispersing agent consisting of the three components (1) and (C) or the two components (1) and (C) may be carried out in a conventional manner.

For example, in one reactor, water, a dispersing agent consisting of components (4), (■), and (C), a polymerization initiator, a chain transfer agent, and if desired, auxiliary agents such as dyes and pigments are added. # The (mixed) monomers are charged and polymerized in a dispersed state while stirring. The monomer and polymerization initiator may be charged in their entirety into the reactor before polymerization, or -@5 may be added at the beginning, and the monomer or polymerization initiator may be added continuously or intermittently as the polymerization progresses. It's okay.

Furthermore, when producing the resin of the present invention, a chain transfer agent such as mercaptan can be used for the purpose of adjusting the molecule t. Examples of mercaptans used are primary, secondary, tertiary mercaptans having alkyl groups or substituted alkyl groups; for example n-butyl mercaptan, isobutyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, aec-butyl mercaptan%5
ee-dodecylmercaptan, tertbutylmercaptan, tert,-dodecylmercaptan; aromatic mercaptans, such as phenylmercaptan, thiocresol, 4-tert,-butyl-O-thiocresol; thioglycolic acid and its esters; ethylene glycol, etc. Examples include mercaptans having 3 to 18 carbon atoms. These can be used alone or in combination of two or more. Among these mercaptans, terL
-butyl mercaptan, n-butyl mercaptan, n-
Preferred are octyl mercaptan, n-dodecyl mercaptan and jerL-dodecyl mercaptan. When using mercaptan, the amount used is 1% per monomer.
It is less than molti. If it exceeds 1 molty, the molecular weight becomes small and the physical properties deteriorate.

As the polymerization initiator added to the monomer, known oil-soluble ones can be used, such as acetyl peroxide, gropionyl peroxide, butyryl peroxide, py, cadrylyl peroxide, octanoyl peroxide, benzoyl peroxide, Diacylsk such as lauroyl peroxide, stearoyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, etc.
oxide; -butyl peracetate, t-butyl A-
peresters such as bivalate, t-butyl peroctanoate, t-butylperpe/soate; 212'-azobisisobutyronitrile, 2,2'-azobis-2,
Examples include azobis compounds such as 4-dimethylvaleronitrile.

The polymerization temperature during suspension polymerization varies depending on the type and amount of the polymerization initiator used, the type of monomer, etc., but in the case of the present invention, it is within the range of 50 to 150°C [2 Further, the weight ratio of the oil phase to the aqueous phase during suspension polymerization is within the range of oil phase/aqueous phase = 1/10 to 1/1, preferably 1/1.2 to 1/3. is within the range of

The polymer beads obtained by the production method of the present invention can be devolatilized and extruded by a known method and shaped into a four-let shape. In this case, it is desirable that the residual N-substituted maleimide in the polymer beads be 1 weight or less in order to suppress coloring of the resin.

This residual monomer removal is achieved by washing with 100 parts by weight or more of a -rimerpeas-insoluble solvent per 100 parts by weight of the polymer beads. If the amount of solvent is less than 100 parts by weight, the cleaning effect will be small, and if the amount exceeds 1000'21E parts, cleaning is possible, but the cleaning effect will not be improved and this is economically disadvantageous. The washing temperature range is from normal humidity to 100°C, and preferably from 35 to 70°C. Examples of solvents include methanol, ethanol, hexane, and the like. In particular, it is preferable to use methanol.

In the resin of the present invention, depending on the product type and quality requirements, small amounts of other comonomers may be used in combination, plasticizers,
A crosslinking agent, a heat stabilizer, a coloring agent, an ultraviolet absorber, a mold release agent, etc. may also be added. [Examples] The present invention will be further explained in detail below with reference to Examples. In the examples, parts indicate parts by weight, and 1% indicates weight %. In addition, (Al and (11) dispersants were synthesized as follows.

Synthesis example (A-1) of dispersant (capacitor component) Methyl methacrylate 30S, potassium methacrylate 70g, deionized water 4009 and 2000M
Ammonium persulfate O,1,!, dissolved in 10 g of deionized water, was heated to 70°C with stirring under a nitrogen atmosphere in a flask of i+ was added and the temperature was raised to 80°C. The mixture was diluted by adding 490.9 g of water after 6 hours and cooled to obtain a cloudy white solution with a polymer concentration of about 10% and a viscosity of about 370 cp (25° C.).

(A-2) Ethyl acrylate 35! ? , except for using 659ft of ammonium methacrylate (A-1)
In the same manner as above, a cloudy white solution with a viscosity of about 260 ep was obtained.

(A-3) A white cloudy solution with a viscosity of about 190 cp was obtained in the same manner as in (A-1) except that 25μ of tutyl acrylate and 75g of potassium methacrylate were used.Dispersant (B) Synthesis example of components (B-1) Sodium salt of 2-sulfonityl methacrylate 100f Deionized water 900. ! i” is the internal volume 2
The mixture was heated to 50°C in a 000rrL flask with stirring under a nitrogen atmosphere, and 0.1 g of ammonium persulfate was added and heated to 60°C. After cooling for 6 hours, the viscosity is approximately 840.
A clear solution with cp f was obtained.

(B-2) A slightly cloudy solution with a viscosity of about 670 cp was obtained in the same manner as in (B-1) except that sodium salt of 2-sulfonityl methacrylate 8011 and methyl methacrylate 20y were used.

(B-3) Except for using 60y1 of sodium salt of 2-sulfonityl methacrylate, 10g of potassium methacrylate, and 30.1% of ethyl methacrylate, all <' (B-1)
In the same manner as above, a cloudy white solution with a viscosity of about 800 cp was obtained.

Evaluations of the properties in Examples were conducted in accordance with the following standards.

vSP (Vickert Softness) ASTM D
1525HDT (heat deformation temperature) AST
M D648 Total ray M pass rate ASTM D1003 Parallel light transmittance ASTM D1003 Haze value ASTM D1003 MFR (flowability, 230℃, load 10kg) ASTM
D1238 tensile strength AST
M D638 tensile elongation AST
M D638 Izot impact strength AST
M D256 Example 1 Contents 270 (l) of deionized water and dispersant components of B-1,0,54,9 and sodium sulfate were charged in a 3500 Qml flask, and methyl methacrylate 80
1,800.9 parts of a monomer solution consisting of 20 parts of N-cyclohexylmaleimide, 0.23 parts of n-octyl mercaptan, and 0.1 part of azobisisobutyronitrile was heated at 35 Orpm in a substantially oxygen-free state. Suspension polymerization was carried out by heating at 80° C. for 2 hours while stirring.

The polymerization system remained stable until the end of the polymerization, and there were almost no giant particles, no polymer particles adhering to the flask wall, no polymer beads floating above the water surface, and the particle size was uniform with an average diameter of 0.28 cm. Polymer beads were obtained. After dehydration and drying, the polymer beads contained 1.4% of methyl methacrylate and N-
Cyclohexyl? +/Imide 0.9% is processed by gas chromatography using conventional methods! ] has been established.

500 parts of methanol was added to 100 parts of the polymer beads, stirred, heated to 40°C for 30 minutes, passed through the mouth, and dried. No particular secondary aggregation was observed. The remaining moa/mar was less than 0.2 inch. 0 parts of distearyl stearate in 100 parts of this polymer bead.
．． 2 parts were added and extruded at 250°C using a small twin-screw extruder equipped with 2 pents, shaped, and used for physical property evaluation. The intrinsic viscosity of this pellet measured in chloroform at 25°C is 0.55 dl.
VSP 211/bit (DT
are respectively 135℃.

The temperature was 119°C. Liquidity MFR is 3.1. It was molded at 250° C. for 10 minutes and the optical properties and mechanical properties were measured, and the following values were obtained.

Total light transmittance 91.9 Haze value 0.9% Plate thickness 2■ Tensile strength 569 to 97 cm Tensile elongation
1.8% Izot impact strength 1.3 kgcm 7c
It is clear that the physical properties as a diacrylic molding material are maintained and the heat resistance is significantly improved compared to M (miltosoch). In addition, the water extraction rate was at a lower level than that of the acrylic molding material ACRIVERA VH (Mitsubishi Rayon Chikara), and there was little deformation due to water absorption, so it could be advantageously used as an optical element.

Using this pellet, a lens with a center wall thickness of 3 mm was molded. Refractive index no == 1.798, dispersion νD = 54.2
It was transparent, had no coloration, had almost no optical distortion, had good mold reversibility, and was sufficiently usable even at 100°C.

Example 2 and Comparative Examples 1 to 4 Using the same equipment as in Example 1, all the dispersant components shown in Table 1 were charged, and the monomer phase contained 80 parts of methyl methacrylate, 20 parts of N-t-butylmaleimide, and n- Octyl mercaptan 0.24 parts, azobisisobutyronitrile 0.
Suspension polymerization was carried out in the same manner as in Example 1, except that 1 part was used, and the results shown in Table 1 were obtained.

The industrial production advantages of the process according to the invention are clear.

υ1~;-de1 White The polymers of Example 2 and Comparative Example 4 were evaluated in the same manner as in Example 1, and the results of Comparative Example 2 were obtained.

Table-2 (Before cleaning) Section) (After cleaning) Section MFR (II/10 minutes) 6.0 6
．． 4 Intrinsic viscosity Cd1l&) 0.57
0.57VSP (C1132130 'HDT (C1116113 tensile strength Ckg/α2) 607 53
4 Tensile elongation Part 1 1.9 1.
6 Izot W$'j'ja (k? ・cm/cm
) 1.31.2 (mild notch) ゛Also, using this pellet, 2 mm (t)
Injection molded a sample of 110 Kaku, manufactured by Takubo Sayaki HD-30.
Grindability was evaluated using a W handrail machine. No polymer adhesion was observed, excellent grindability was obtained, and lens processing was also possible by grinding. It should be noted that the acrylic resin used for comparison (Acrivet VH manufactured by Mitsubishi Rayon Co., Ltd.) had polymer adhesion.

Examples 3 to 5 and Comparative Examples 5 and 6 Using a pressure-resistant polymerization pot with an internal volume of 50 tons, 30 kg of deionized water and all of the various dispersion components shown in Table 3 were charged, and the monomer phase composition was also prepared in the proportions shown in Table 2. 15 to 9, and while stirring at 180 rpm, 110t/nitrogen was added.
Fl! 80℃ after bubbling for 20 minutes at a flow rate of 11.
The mixture was heated for 2 hours to undergo suspension polymerization, then heated to 105°C, kept for 15 minutes, post-treated, cooled, and dried. The resulting polymer piece was washed with methanol in the same manner as in Example 1, filtered and dried, and then pressed and molded in the same manner as in Example 1 to obtain a hardlet. Comparative Example 5 (The heat treatment and methanol washing after the combination were omitted, and the rest was the same as that of Example 5.
Pellets were obtained by carrying out exactly the same treatment as above.

Table 4 shows the results of physical property evaluation of the obtained polymer.

In Comparative Example 6, the same method as in Example 5 was repeated except that N-phenylmaleimide was used instead of N-t-butylmaleimide, and the degree of coloring of the polymer was determined by AST.
Y, I by M-D-1925.

It was determined as a first shift (yellowness index) and compared.

In Comparative Example 6, the polymer was colored yellow, and Y, 1.
The value was 14, while in Examples 3 to 5, it was colorless and transparent, Y, 1. All values are 3.5 or less, and compared to Comparative Example 6, υ
It was excellent.

pJ, C total; P Compared with Example 5, Comparative Example 5 was significantly inferior in heat resistance, mechanical properties, and optical properties.〇 2 mmt injection molding of Example 3 Temperature: 60℃, carbon arc lamp, 1 hour a, C using a manufactured weather resistance tester
A 1,000-hour accelerated exposure test was carried out under a 12-minute rainstorm, but there was almost no change in appearance and the product had excellent weather resistance.

The 3 mm thick injection molded specimen of Example 3 was immersed in pure water at 100° C. for 4 hours and the degree of whitening was visually judged. As a result, no particular change was observed and the boiling resistance was good.

From the above, it can be confirmed that the resin composition of the present invention has sufficient characteristics as an acrylic resin.

〔Effect of the invention〕

The resin of the present invention has excellent optical properties (mechanical properties, weather resistance, and moldability) almost comparable to polymethyl methacrylate, and has excellent heat resistance and productivity.

Since the resin of the present invention has the above-mentioned properties, it is useful for the following uses.

It is useful in fields where acrylic resin is used, such as signboards, lighting covers, nameplates, automobile parts, electrical equipment parts, decorations, and miscellaneous goods. In particular, it can be used in fields that require high heat resistance.

It is also used in the field of optical elements, especially for lenses.
, has a refractive index of <<, has high heat resistance, low moisture absorption, and has excellent surface properties and processability necessary for lenses, so it has excellent morphological stability and can be used in a wide range of environments compared to acrylic resin. (Examples include pickup lenses, lenses for glasses, lenses for cameras, Fresnel lenses for projectors, etc.) It is also used as a substrate for optical disks and as a core or sheath material for optically transmitting fibers.

Claims (1)

[Claims] 1. 99 to 70% by weight of methyl methacrylate and N-
A copolymer consisting of 1 to 30% by weight of cyclohexylmaleimide and/or Nt-butylmaleimide, and having an intrinsic viscosity of 0.3 to 30% by weight as measured in chloroform at 25°C.
1.0 dl/g, the amount of residual methyl methacrylate in the copolymer is 1.0% by weight or less, and the amount of residual N-cyclohexylmaleimide and/or N-t-butylmaleimide is 0.3% by weight or less. A heat-resistant resin characterized by: 2. 90-70% by weight of methyl methacrylate and N-
A monomer mixture consisting of 1 to 30% by weight of cyclohexylmaleimide and/or Nt-butylmaleimide,
The following three components (A), (B) and (C), or (B
) and (C), suspension polymerization is carried out in the presence of two components, 2
The intrinsic viscosity measured in chloroform at 5°C is 0.3 to 1.
0 dl/g, the amount of residual methyl methacrylate in the copolymer is 1.0% by weight or less, and the total amount of residual N-cyclohexylmaleimide and/or N-t-butylmaleimide is 0.3% by weight or less. A method for producing a heat-resistant resin, characterized by obtaining a polymer. (A) (a) 0 to 60% by weight of an acrylic acid alkyl ester and/or methacrylic acid alkyl ester (I) having an alkyl group having 1 to 12 carbon atoms, and lithium and sodium acrylic acid and/or methacrylic acid;
Salt of acrylic acid and/or methacrylic acid selected from the group consisting of potassium and ammonium salts (II) 10
Water-soluble polymer obtained by polymerizing 0 to 40% by weight, (B) (a) Acrylic acid alkyl ester and/or methacrylic acid alkyl ester having an alkyl group having 1 to 12 carbon atoms (I) 0 to 60 (b) at least one salt of acrylic acid and/or methacrylic acid selected from the group consisting of lithium, sodium, potassium and ammonium salts of acrylic acid and/or methacrylic acid (II) 0 to 20% by weight; and (c) General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼...(1) However, R, R', R''=H or CH_3, X=-O
-, -NH- or ▲Mathematical formulas, chemical formulas, tables, etc.▼
, M=H, Li, Na, K or NH_4, a water-soluble polymer obtained by polymerizing 100 to 20% by weight of an acrylic acid derivative or methacrylic acid derivative (III) represented by an integer of n=1 to 3. , (C) an electrolyte having a monovalent cation. 3. The method for producing a copolymer resin according to claim 2, wherein 100 parts by weight of polymer beads obtained by suspension polymerization are washed with 100 parts by weight or more of a polymer-insoluble solvent. 4. 99-70% by weight of methyl methacrylate and N-
A copolymer consisting of 1 to 30% by weight of cyclohexylmaleimide and/or Nt-butylmaleimide, and having an intrinsic viscosity of 0.3 to 30% by weight as measured in chloroform at 25°C.
1.0 dl/g, the amount of residual methyl methacrylate in the copolymer is 1.0% by weight or less, and the total amount of residual N-cyclohexylmaleimide and/or N-t-butylmaleimide is 0.3% by weight or less. An optical element characterized by being made of a certain heat-resistant resin.