JP2592332B2 - Maleimide copolymer and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a novel maleimide-based copolymer having excellent heat resistance, transparency, chemical resistance, impact resistance, and moldability. The present invention relates to the manufacturing method.

[Conventional technology]

Recently, applications of transparent molding materials have been expanding. For example, there are an optical information recording carrier such as a video disk and an audio disk, a camera, a lens such as an optical pickup, a head lamp of an automobile, and the like. For these uses, there is an increasing demand for materials having high heat resistance and impact resistance.

Up to now, polycarbonate resin has been mainly used as a transparent heat-resistant molding material. Polycarbonate resin is a transparent resin having excellent heat resistance and impact resistance. But,
There are some disadvantages for the applications described above. First, they are relatively expensive, and are inferior in chemical resistance, moldability and the like. These disadvantages limit their use.

Various copolymers of a maleimide-based monomer and another vinyl-based monomer have been proposed as resins having excellent heat resistance (JP-A-58-162616, JP-A-61-276807, JP-A-60-79019). However, the maleimide copolymers proposed therein are not satisfactory for the above-mentioned applications. In particular, there is hardly any literature characterized by improvement of coloring (reduction of yellowness) which is essential for transparent molding materials. In the polymerization using a maleimide-based monomer, there are many examples of emulsion polymerization and suspension polymerization. However, coloring by an emulsifier and other auxiliaries is not an appropriate method. Also, in the case of bulk polymerization or solution polymerization, if the polymerization is carried out with care, only a copolymer having a wide molecular weight distribution and a poor transparency can be obtained.

[Problems to be solved by the invention]

Since the maleimide-based copolymer aimed at by the present invention requires heat resistance equivalent to that of a polycarbonate resin, the maleimide-based monomer requires a specific amount or more. Inferiority, fluidity etc. will be inferior. The charged composition including other vinyl monomers must be within a specific range.

In order to improve transparency and other properties, bulk polymerization or solution polymerization is preferred, but maleimide-based monomers have a very fast polymerization rate, and are easy to homopolymerize, and have a wide molecular weight distribution and composition distribution. It tends to have poor properties such as impact resistance. Further, if an unreacted maleimide-based monomer is present in the copolymer, transparency is poor and coloring is remarkable. For this reason, sufficient study is required for the polymerization method and the subsequent devolatilization of the unreacted monomer and the organic solvent.

The present inventors have studied these problems diligently, and as a result, in performing the polymerization of the maleimide-based copolymer, a specific monomer mixing ratio and a specific mixing ratio with a specific organic solvent are determined by a specific method. The present inventors have found that a desired maleimide-based copolymer can be obtained by continuous polymerization and devolatilization of an unreacted monomer and an organic solvent in a devolatilization apparatus, and have reached the present invention.

[Means for solving the problem]

That is, the gist of the present invention is that the maleimide monomer unit (a) exceeds 28% by weight and 65% by weight or less, and is selected from the group consisting of an aromatic vinyl monomer and a methacrylate monomer. At least one monomer unit (b) 16
At least 72% by weight and 0 to 25% by weight of the other vinyl monomer unit (c) (however, the total amount of the unit components (a) to (c) is 100% by weight). (1) the content of the residual maleimide-based monomer in the copolymer is 0.1% by weight or less, and the total volatile content other than the maleimide-based monomer is 0.5% by weight or less; 2) The ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn in the copolymer is 3 or less; (3) the yellow index of the copolymer is 30 or less; The first maleimide copolymer having a viscosity of 0.3 to 1.5 (dl / g).
And at least one monomer selected from the group consisting of an aromatic vinyl monomer and a methacrylate ester monomer in an amount of more than 28% by weight and not more than 65% by weight of a maleimide monomer unit (a) Body unit (b) 16% by weight or more and less than 72% by weight and other vinyl monomer units (c) 0 to 25% by weight (however, (a) to
(C) a group consisting of a maleimide-based monomer, an aromatic vinyl-based monomer and a methacrylate-based monomer when producing a maleimide-based copolymer composed of a total amount of unit components of 100% by weight); At least one monomer selected from the group consisting of an organic solvent and a weight ratio of the monomer and the organic solvent of 3: 2
The copolymerization reaction is continued by continuously supplying dropwise to the complete mixed polymerization reactor so as to be in the range of 9: 1, and the polymerization conversion rate of all monomers charged in the reaction system is 30 to 70% by weight. Steady state by continuously taking out the polymerization reactant containing unreacted monomer and organic solvent from the complete mixed polymerization reactor so that the monomer composition and the concentration of the polymerization reactant are always kept constant within the range of The resulting maleimide is characterized in that continuous polymerization under the above conditions is continued, the polymerization reaction product obtained thereafter is transferred to a devolatilizer, and the unreacted monomers and organic solvent are devolatilized under reduced pressure. The content of the residual maleimide-based monomer in the copolymer is 0.1% by weight or less, and the total volatile content other than the maleimide-based monomer is 0.5% by weight or less, the weight average molecular weight Mw and the number average molecular weight Mn The ratio Mw / Mn is 3 or less, and the yellow index is 30 or less. , And the and in the second invention the intrinsic viscosity is the manufacturing method of the maleimide copolymer is 0.3 to 1.5.

The maleimide monomer (a) in the present invention is represented by the following formula (I): (In the formula, R represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a cyclohexyl group, an aryl group or a substituted aryl group.) For example, maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N- Isopropyl maleimide, N-cyclohexyl maleimide, N-
Phenylmaleimide, N-tolylmaleimide, N-xylylmaleimide, N-naphthylmaleimide, Nt
-Butylmaleimide, N-orthochlorophenylmaleimide, N-orthomethoxyphenylmaleimide and the like. Of these, N-cyclohexylmaleimide, N
-Phenylmaleimide, N-orthochlorophenylmaleimide and N-orthomethoxyphenylmaleimide are preferred, with N-cyclohexylmaleimide and N-phenylmaleimide being particularly preferred. These maleimide monomers can be used alone or in combination of two or more.

The content of the maleimide-based monomer unit (a) in the maleimide-based copolymer of the present invention is in the range of more than 28% by weight and 65% by weight or less, preferably in the range of more than 28% by weight and 55% by weight or less. It is necessary. If the content is 28% by weight or less, the heat resistance of the maleimide-based copolymer is low, which is not preferable because it is inferior to polycarbonate resins. Also 65
A content exceeding the weight% is not preferable because the maleimide-based copolymer becomes inferior in impact resistance and fluidity.

Examples of the aromatic vinyl monomer (b) in the present invention include styrene, α-methylstyrene, paramethylstyrene, t-butylstyrene, crossstyrene, vinyltoluene and the like, and styrene and α-methylstyrene are preferred. Things.

Further, as the methacrylate monomer (b) in the present invention, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, phenyl methacrylate, isobornyl methacrylate, benzyl methacrylate, trifluoroethyl methacrylate, etc. And methyl methacrylate is preferred.

In the present invention, as the component (b), at least one monomer selected from the group consisting of the above-mentioned aromatic vinyl monomers and methacrylic acid ester monomers is used, and the maleimide copolymer of the present invention is used. At least one of such an aromatic vinyl monomer and a methacrylate ester monomer
The content of the kind of monomer unit (b) is 16% by weight or more and 72% by weight
It is necessary to be within the range of less than 29% by weight, preferably less than 29% by weight. If the content is less than 16% by weight, the moldability of the maleimide-based copolymer will be low.
On the other hand, when the content is 72% by weight or more, the content of the maleimide-based monomer unit is decreased, and the heat resistance of the obtained maleimide-based copolymer is undesirably low.

Further, other vinyl monomers (C) used as optional components in the present invention include vinyl cyanide monomers, acrylate monomers, unsaturated dicarboxylic anhydrides and vinyl carboxylic acid monomers. Body and the like.
Examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, fumaronitrile and the like, and acrylonitrile is preferred. Examples of the acrylate monomer include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and cyclohexyl acrylate. Further, as the unsaturated dicarboxylic anhydride, anhydrides such as maleic acid, itaconic acid and citraconic acid can be mentioned, and maleic anhydride is preferable. Further, examples of the vinyl carboxylic acid monomer include acrylic acid and methacrylic acid. Acrylonitrile, maleic anhydride and methacrylic acid are preferably used. These other vinyl monomers (C) can be used alone or in combination of two or more, but they need not necessarily be used.

The content of the unit (C) based on such another vinyl monomer in the maleimide-based copolymer of the present invention is in the range of 0 to 25% by weight, preferably 0 to 19% by weight, more preferably 0 to 25% by weight.
It is in the range of 16% by weight. If the content exceeds 25% by weight, the properties of the obtained maleimide-based copolymer deviate from the object of the present invention, which is not preferable.

The maleimide-based copolymer of the present invention comprises at least one monomer unit selected from the group consisting of the maleimide-based monomer unit (a), an aromatic vinyl-based monomer and a methacrylate-based monomer ( The total amount of b) and the content of the other vinyl monomer units (c) is adjusted to be 100% by weight. As the other vinyl monomers, vinyl cyanide monomers, especially In the case of using acrylonitrile, the composition ratio (% by weight) of the unit component (a), the unit component (b) and the unit component (c) is shown by the triangle coordinates (a) / (b) in FIG.
/ (C) = 28/64/8 (A), (a) / (b) /
(C) = Point (B) where 65/16/19, (a) / (b) /
(C) = points (C) = 28/72/0 and (a) / (b) /
(C) = four points (A) of point (D) with 65/35/0,
A range surrounded by a quadrilateral having vertices of (B), (C) and (D), and (a) /
(A) where (b) / (c) = 30/69/9, (a) /
(B) / (c) = 55/29/16 (B ′), (a) /
(B) / (c) = 30/70/0 (C ′) and (a)
/ (B) / (c) = 55/45/0 A quadrilateral with the vertices of the four points (A '), (B'), (C ') and (D') of the point (D ') Heat resistance, transparency,
It is particularly preferable because it can be a maleimide copolymer excellent in fluidity and the like.

Further, the maleimide-based copolymer of the present invention has a content of residual maleimide-based monomer in the copolymer of 0.1% by weight or less, preferably 0.05% by weight or less, and a total volatilization other than the maleimide-based monomer. It must be less than 0.5% by weight, preferably less than 0.4% by weight. When the content of the residual maleimide-based monomer exceeds 0.1% by weight, the coloring of the copolymer is remarkable, and the transparency often deteriorates, and disadvantages such as poor weather resistance and easy thermal coloring occur. Absent. Furthermore, when molding is performed using the copolymer, bleed-out occurs and a good molded product may not be obtained, which is not preferable. The total volatile components other than the maleimide-based monomer include the constituent monomers and the organic solvent.
When it is present in an amount exceeding 0.5% by weight, the heat resistance of the maleimide-based copolymer is inferior, and silver streaks occur when molded at a high temperature using the copolymer, and a good molded product is obtained. It is not preferred.

Also, the weight average molecular weight of the maleimide copolymer of the present invention.
The ratio Mw / Mn of Mw to the number average molecular weight Mn is 3 or less, preferably 2.8
Below, it is more preferable that it is 2.5 or less. The ratio of Mw / Mn is widely used as a measure of the spread of the molecular weight distribution, but if this value is larger than 3, the impact resistance and transparency of the maleimide-based copolymer will be poor. Not preferred. In the present invention, the weight average molecular weight Mw and the number average molecular weight Mn can be determined by converting an elution curve determined by gel permeation chromatography (GPC) into standard polystyrene.

Furthermore, the maleimide copolymer of the present invention must have a yellow index (yellowness, YI) of 30 or less, preferably 25 or less. Yellow index refers to the value measured as a value of a molded plate molded using the obtained maleimide-based copolymer, the amount of residual maleimide-based monomer in the maleimide-based copolymer and other vinyl When a vinyl cyanide monomer is used as the monomer, there is a close relationship with the amount of the residual monomer. If the yellow index is more than 30, the composition distribution of the maleimide-based copolymer contains a structural factor that is likely to cause thermal coloring when molded widely, so that the transparency and impact resistance are deteriorated, which is not preferable. .

Furthermore, the intrinsic viscosity of the maleimide-based copolymer of the present invention is 0.1.
It needs to be in the range of 3 to 1.5 (dl / g), preferably 0.5 to 1.2 (dl / g). The intrinsic viscosity is a value obtained by dissolving a maleimide-based copolymer in N, N-dimethylformamide and measuring the resultant at 25 ° C. with an Ubbelohde viscometer. A maleimide copolymer having an intrinsic viscosity of less than 0.3 (dl / g) has low impact resistance,
A maleimide copolymer having an intrinsic viscosity of more than 1.5 (dl / g) has high impact resistance, but has poor fluidity, making molding difficult and impractical.

The maleimide-based copolymer of the present invention satisfies all the conditions of the residual maleimide-based monomer amount, the total volatile content other than the maleimide-based monomer, the Mw / Mn ratio, the yellow index and the intrinsic viscosity as described above. It is necessary.

The method for producing the maleimide-based copolymer of the present invention is basically bulk polymerization, but the addition of an organic solvent into the reaction system is essential. That is, first maleimide monomer,
At least one monomer selected from the group consisting of an aromatic vinyl monomer and a methacrylic acid ester monomer, and optionally another maleimide monomer and an organic solvent, and optionally a polymerization initiator, Copolymerization by continuous drop-wise feeding to a complete mixing polymerization reactor so that the weight ratio of the monomer and the organic solvent is in the range of 3: 2 to 9: 1, preferably 3: 2 to 8: 2. It is necessary to continue the reaction. In the region where the amount of the organic solvent is smaller than the amount of the monomer than the range of the weight ratio of the monomer and the organic solvent, the viscosity of the reaction system becomes high during the polymerization and the stirring becomes difficult. Also, it is difficult to take out the polymerization reaction product from the reaction mixture. In addition, when the viscosity increases, heat transfer becomes poor, causing temperature non-uniformity in the reaction system, which causes the molecular weight distribution and the composition distribution to spread. On the other hand, in a region where the amount of the organic solvent is larger than the amount of the monomer, the polymerization rate becomes slower, and it is difficult to remove the organic solvent in the devolatilization step, thereby lowering the productivity.

In practicing the present invention, the aforementioned maleimide-based monomers, aromatic vinyl-based monomers, methacrylate-based monomers, and other vinyl-based monomers can be used.

Since these monomers have different polymerization activities, when obtaining a copolymer having the above composition, the composition of the charged monomer mixture is appropriately selected depending on their polymerization activities. A preferred composition of the charged monomer mixture is a maleimide monomer 7 to
50 parts by weight, 40 to 90 parts by weight of an aromatic vinyl monomer and a methacrylic acid ester monomer, and 0 to 30 parts by weight of another vinyl monomer optionally added (however, (a) to (c) )
(The total amount of the monomers is 100 parts by weight).

Further, the organic solvent that can be used in carrying out the present invention does not itself polymerize, does not hinder the polymerization of the above monomers, and can dissolve the maleimide copolymer of the present invention. It is necessary. Specific examples of such organic solvents include methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, acetophenone, benzene, toluene, ethylbenzene, xylene, tetrahydrofuran, N, N-dimethylformamide and the like.

Further, in carrying out the polymerization in the practice of the present invention, a polymerization initiator can be added as required. As the polymerization initiator, generally known organic peroxides and azo compounds can be used. Ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxyesters, peroxydicarbonates, etc. are used as the organic peroxides. Period temperature is 80 ~
Those in the range of 140 ° C. are preferred. Specific examples of the organic peroxide include methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, methylcyclohexanone peroxide, acetylacetone peroxide, 1,1-dibutylperoxy-3,3,5-trimethylcyclohexane, and 1,1-dibutyl. Peroxycyclohexane, 2,2-di-t-butylperoxybutane, 2,2,4-trimethylpentyl-2-hydroperoxide, dicumyl peroxide, 2,5-dimethyl-2,5-di- ( t-
Butylperoxy) hexane, t-butylcumyl peroxide, di-t-butylperoxide, tris-
(T-butylperoxy) triazine, di-t-butylperoxyhexahydroterephthalate, di-t-butylperoxyazelate, t-butylperoxyacetate, t-butylperoxybenzoate, t-butylperoxylau Rate, t-butyl peroxyisopropyl carbonate and the like. Specific examples of azide compounds include 1,1'-azobis (cyclohexane-
1-carbonitrile), 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 2,2'-azobis (2,4,4-trimethylpentane) and the like.

As described above, the method for producing a maleimide-based copolymer according to the present invention is to continuously carry out the polymerization reaction from the reaction system after continuing the copolymerization reaction under a specific range of the weight ratio of the monomer and the organic solvent. What is important is that the monomer and the organic solvent are continuously supplied to the reaction system and the so-called continuous polymerization is carried out. This makes it possible to produce a maleimide copolymer having a narrow composition distribution and molecular weight distribution.

That is, the weight ratio of the monomer and the organic solvent is 3: 2 as described above.
The copolymerization reaction is continued by continuously dropping the mixture into a complete mixed polymerization reactor so as to be in the range of ~ 9: 1, and the polymerization conversion rate of all the monomers charged in the reaction system is 30 to 70%. The polymerization reaction product containing the unreacted monomer and the organic solvent is always mixed from the complete polymerization reactor so that the monomer composition and the concentration of the polymerization reaction product and the concentration of the polymerization initiator as required are kept constant within the range. It is important to continue continuous polymerization under a steady state by taking out continuously. Polymerization conversion rate is 30
%, It is not preferable because it is difficult to remove unreacted monomers in a devolatilizing apparatus described later. Further, when the polymerization conversion is increased in a second polymerization reactor provided as required, which will be described later, the molecular weight distribution and the composition distribution are widened, and the impact resistance and the transparency are deteriorated. On the other hand, if the polymerization is carried out to a state where the polymerization conversion rate exceeds 70%, the viscosity of the reaction system becomes high, stirring becomes difficult, and it becomes difficult to take out the polymerization reaction product. In addition, the molecular weight distribution and the composition distribution are widened and the impact resistance and the transparency are deteriorated, which is not preferable.

In the present invention, at least the unreacted maleimide-based monomer is polymerized in a second polymerization reactor provided with a polymerization reaction product taken out after such an operation as required, and then the obtained polymerization reaction product is devolatilized. It is necessary to transfer to an apparatus and devolatilize unreacted monomers and organic solvents under reduced pressure.

The polymerization conversion can be further increased in the second polymerization reactor. However, it is not preferable to increase the degree of polymerization so much in the present polymerization reactor in which the monomer is not continuously supplied. However, before reaching the subsequent devolatilization step, the unreacted maleimide-based monomer in the polymerization reaction product must be polymerized. If devolatilization is carried out in the presence of unreacted maleimide-based monomers, the resulting maleimide-based copolymer becomes extremely colored, which is not preferable.

As the devolatilizing device, a multi-vent type devolatilizing extruder, a flash type devolatilizing device, a thin film type devolatilizing device and the like are preferably used.
Further, a device obtained by combining a plurality of these devices can also be used.

In the present invention, the content of the residual maleimide-based monomer in the obtained maleimide-based copolymer is 0.1% by weight or less, and the total volatile components other than the maleimide-based monomer are obtained through the above-described various processes. Is 0.5% by weight or less,
The ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn is 3 or less, the yellow index is 30 or less, and the intrinsic viscosity is 0.3 to 1.5 (dl / g).

The maleimide copolymer according to the present invention can be used in the same manner as ordinary thermoplastic resins for injection molding, extrusion molding and the like. Further, since it has better chemical resistance than polycarbonate resin, it can be used for coating. Furthermore, since it is suitable for surface treatment such as plating, vapor deposition, and sputtering, it can be used for a wider range of applications than conventional transparent heat-resistant materials.

[Examples] Hereinafter, the present invention will be specifically described with reference to Examples. In the following description, “parts” means “parts by weight”. Various measuring methods were performed according to the following methods.

The amount of the polymer in the polymerization reaction solution was calculated from the weight of the polymer obtained by diluting the polymerization reaction product with methyl ethyl ketone and reprecipitating with methanol. Using the reprecipitated polymer, composition analysis, intrinsic viscosity, GPC measurement, and the like were performed.

The amounts of unreacted monomers and residual monomers after devolatilization in the polymerization reaction solution were measured by gas chromatography.

The composition of each monomer unit of the polymer was calculated from the absorption of each characteristic group in infrared absorption spectrum measurement.

The intrinsic viscosity [η] of the polymer was determined at 25 ° C. using an Ubbelohde viscometer after dissolving the polymer in N, N-dimethylformamide.

Weight average molecular weight (Mw) and number average molecular weight (Mn) of polymer
The ratio Mw / Mn was calculated from the elution curve of GPC by the ratio of Mw to Mn calculated based on a standard polymer of polystyrene.

Melt flow index (MI) was determined by ASTM D-1238 as a discharge amount (g) for 10 minutes at 230 ° C. under a load of 10 kg.

The polymer was also heated to cylinder temperature on a 1 ounce injection molding machine.
Using a test piece molded at 260 ° C., Izod impact strength, Rockwell hardness, bicut softening temperature, yellow index (YI) total light transmittance, and haze were measured by the following methods.

Izod impact strength: ASTM D-256 (with 1/4 "notch) Rockwell hardness: ASTM D-785 (unit: M scale) Vikat softening temperature: ASTM D-1525 (5kg load) Yellow Index (YI): ASTM D- 1925 (measured on a 3 mm thick molded plate) Total light transmittance: ASTM D-1003 (measured on a 3 mm thick molded plate) Haze: ASTM D-1003 Examples 1 to 5 Maleimide using the production apparatus shown in FIG. Production of a system copolymer was carried out.

First, air in the first polymerization reactor (completely mixed polymerization reactor) 1 was removed by a vacuum pump, and then nitrogen gas was introduced into the reactor to form a nitrogen atmosphere. This operation was repeated one more time to completely replace the inside of the vessel with a nitrogen atmosphere, and then a polymerization experiment was performed.

That is, the mixed liquid A and the mixed liquid B in the ratios shown in Table 1 were continuously dropped and supplied to the first polymerization reactor 1 from separate pipes,
A copolymerization reaction was carried out under the conditions of polymerization temperature and residence time shown in Table 1, and the amount equal to the total amount of the charged monomers when the polymerization conversion of the charged monomers reached the value shown in Table 1. Was continuously extracted from the bottom of the reactor with the gear pump 2 to perform a continuous operation. The polymerization reaction liquid exiting the first polymerization reactor 1 was transferred to a second polymerization reactor 3 of an extrusion flow type by a gear pump 2. In the second polymerization reactor 3, the polymerization was further advanced in the operation temperature range shown in Table 2 to greatly reduce the amount of the remaining maleimide-based monomer. Thereafter, the polymerization reaction product was supplied from the second polymerization reactor 3 to the devolatilizing extruder 5 by the gear pump 4. Table 2 shows the composition of the polymerization reaction solution at the outlet of the second polymerization reactor.
It was shown to. The devolatilizing extruder 5 at this time is a twin vent extruder of a two vent type (V ₁ and V ₂ in FIG. ₂ ). After removing the residual monomer, organic solvent, and the like in the devolatilizing extruder 5, the mixture was pelletized by a pelletizer 6 to obtain a transparent pellet.
Table 3 shows the operating conditions of the devolatilizing extruder 5 and the contents of the residues and monomer units in the obtained various maleimide-based copolymers. Table 4 shows various physical property values of the obtained maleimide-based copolymers.

Comparative Example 1 A maleimide copolymer was prepared under the same polymerization recipe and polymerization conditions as in Example 1 except that the barrel temperature in the devolatilizing extruder 5 and the degree of vacuum in the vent portion (V ₂ ) were set to the conditions shown in Table 3. A coalescence was obtained.
The total volatile content in the maleimide-based copolymer showed a high value of 1.02% by weight. Various production conditions and physical properties are shown in Tables 1 to 4.

Comparative Example 2 (Production of Maleimide Copolymer by Emulsion Polymerization Method) A glass reactor with a stirrer of No. 5 was charged with the following composition.

Pure water 200 parts Sodium dodecylbenzenesulfonate 2 parts Rongalit 0.5 parts Ferrous sulfate 0.005 parts Disodium ethylenediaminetetraacetate 0.01 parts Heat the charge to 60 ° C, and mix the following mixture with the internal temperature of 60 ° C
, And continuously dropped over 3 hours. After completion of the dropwise addition, the mixture was kept at 60 ° C. for 1 hour and then cooled.

Acrylonitrile 15 parts Styrene 55 parts N-phenylmaleimide 30 parts Cumene hydroperoxide 0.5 parts The obtained maleimide-based copolymer latex is coagulated with magnesium sulfate, dehydrated and dried to obtain a white powdered maleimide-based copolymer. Obtained. Tables 3 and 4 show the results of measuring various physical properties.

Comparative Example 3 Without using the second polymerization reactor 3, the polymerization reaction product was directly supplied from the outlet of the first polymerization reactor to the devolatilization extruder 5 via the gear pump 2, and the vent in the devolatilization extruder 5 was used. A maleimide-based copolymer was obtained under the same polymerization recipe and conditions as in Example 1 except that the degree of vacuum in part (V ₂ ) was changed to the conditions shown in Table 3.
Various production conditions and physical properties are shown in Tables 1 to 4. A residual maleimide-based copolymer was obtained.
Was lower than that of the maleimide-based copolymer obtained in (1). In addition, a large amount of silver streaks occurred on the molded plate during molding.

Comparative Example 4 A maleimide-based copolymer was obtained under the same polymerization recipe and polymerization conditions as in Example 1, except that a mixture obtained by further adding 0.3 parts of tertiary decyl mercaptan as a chain transfer agent to mixture A was used. Table 1 shows various production conditions and physical property values.
The results are shown in Table 4. In particular, the intrinsic viscosity was low, and the Izod impact strength was low.

Comparative Example 5 As shown in Table 1, a maleimide-based copolymer was obtained under the same polymerization recipe and under the same polymerization conditions as in Example 1 except that the experiment was performed under the condition that the ratio of methyl ethyl ketone was higher than that in Example 1. Various production conditions and physical properties are shown in Tables 1 to 4.
Methyl ethyl ketone was not completely removed in the devolatilization step, and the heat resistance was low.

Comparative Example 6 As shown in Table 1, a polymerization reaction was carried out under the same polymerization recipe and polymerization conditions as in Example 1 except that the ratio of methyl ethyl ketone was lower than that in Example 1. With the progress of the reaction, the viscosity in the reactor increased and stirring became impossible, so the polymerization was stopped.

Comparative Example 7 As shown in Table 1, a polymerization reaction was carried out with the same formulation as in Example 1 under the condition that the amount of N-phenylmaleimide charged was small to obtain a maleimide-based copolymer. Various production conditions and physical properties are shown in Tables 1 to 4.

[Effect of the Invention] The maleimide copolymer of the present invention is excellent in heat resistance, transparency, chemical resistance, impact resistance, molding workability, etc. by having the above-described composition content and various physical properties, Furthermore, the method for producing a maleimide-based copolymer of the present invention can produce a maleimide-based copolymer having various excellent properties by employing the special bulk polymerization method as described above, and has excellent effects. .

[Brief description of the drawings]

FIG. 1 shows triangular coordinates of a preferable composition range of the maleimide-based copolymer according to the present invention, and FIG. 2 shows an example of a production apparatus for carrying out the present invention. In FIG. 1, 1 is a first polymerization reactor. (Completely mixed polymerization reactor), 2 and 4 are gear pumps, 3 is the second
A polymerization reactor, 5 indicates a devolatilizing extruder, and 6 indicates a pelletizer.

Claims (2)

(57) [Claims] 1. A maleimide monomer unit (a) comprising more than 28% by weight and not more than 65% by weight of at least one monomer selected from the group consisting of an aromatic vinyl monomer and a methacrylate monomer. Monomer unit (b) from 16% by weight to less than 72% by weight and other vinyl monomer units (c) from 0 to 25% by weight (provided that the total amount of unit components (a) to (c) is 100% by weight) (1) The content of the residual maleimide-based monomer in the copolymer is 0.1% by weight or less, and the total volatile content other than the maleimide-based monomer is 0.5%. (2) weight average molecular weight Mw and number average molecular weight of the copolymer
The ratio Mw / Mn of Mn is 3 or less, (3) the yellow index of the copolymer is 30 or less, and (4) the intrinsic viscosity of the copolymer is 0.3 to 1.5 (dl / g). A maleimide-based copolymer, characterized in that: 2. A maleimide monomer unit (a) comprising more than 28% by weight and not more than 65% by weight of at least one monomer selected from the group consisting of aromatic vinyl monomers and methacrylate monomers. Monomer unit (b) from 16% by weight to less than 72% by weight and other vinyl monomer units (c) from 0 to 25% by weight (provided that the total amount of unit components (a) to (c) is 100% by weight) In producing the maleimide-based copolymer, at least one selected from the group consisting of a maleimide-based monomer, an aromatic vinyl-based monomer, and a methacrylate-based monomer.
The seed monomers and the organic solvent are co-dispersed by continuously dropping the monomers and the organic solvent to the complete mixed polymerization reactor so that the weight ratio of the monomers and the organic solvent is in the range of 3: 2 to 9: 1. The polymerization reaction is continued, and the unreacted monomer is maintained so that the polymerization conversion of all the charged monomers in the reaction system is always in the range of 30 to 70% by weight and the monomer composition and the concentration of the polymerization reaction product are kept constant. The polymerization reaction containing the monomer and the organic solvent is continuously taken out from the complete mixed polymerization reactor to continue the continuous polymerization under a steady state, and then the polymerization reaction product obtained is transferred to a devolatilization apparatus. The reaction monomer and the organic solvent are devolatilized under reduced pressure, wherein the content of the residual maleimide monomer in the obtained maleimide copolymer is 0.1% by weight or less, and The total volatile content other than the monomer is 0.5% by weight or less, and the weight average molecular weight Mw and the number average The ratio Mw / Mn of the molecular weight Mn of 3
The method for producing a maleimide-based copolymer having a yellow index of 30 or less and an intrinsic viscosity of 0.3 to 1.5 (dl / g).