JPH1067825A - Maleimide copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a maleimide copolymer having excellent heat resistance and impact resistance and good melt moldability. SOLUTION: This copolymer comprises 80.0-40.0wt.% units (A) derived from an aromatic vinyl monomer, 20.0-60.0wt.% units (B) derived from a maleimide monomer and units (C) derived from monomers copolymerizable therewith (the total amount of units A, B and C being 100.0wt.%) and contains at least 95wt.% molecules each of which has a unit B content in the range of the average value ±10%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a maleimide copolymer having high heat resistance and impact resistance, excellent heat stability, and excellent processability. More specifically, the present invention relates to a maleimide-based copolymer having a homogeneous copolymer composition and effective as a molding material or as a material for improving various properties such as heat resistance by being mixed with a thermoplastic resin.

[0002]

2. Description of the Related Art It is known that a maleimide copolymer obtained by copolymerizing a maleimide monomer and an aromatic vinyl monomer is a thermoplastic resin having a high heat deformation temperature and a high thermal decomposition temperature. Have been. When a radical polymerization of a maleimide-based monomer and an aromatic vinyl-based monomer is performed, the molar ratio of the maleimide-based monomer unit to the aromatic vinyl-based monomer unit is 1: 1 because of high alternating copolymerizability. The alternating copolymer of 1 is preferentially obtained, and thereafter, a homopolymer of an excessive monomer is obtained. Since the 1: 1 alternating copolymer has a high heat distortion temperature, it requires a very high temperature for melt molding and has a drawback of being brittle. Further, a heterogeneous copolymer in which a 1: 1 alternating copolymer and a homopolymer are mixed has a drawback that the toughness is poor.

Until now, various efforts have been made to obtain a copolymer having a homogeneous composition. For example, in U.S. Pat. No. 2,971,939, after a vinyl monomer is charged into a reaction system and polymerization is started, a maleimide monomer is uniformly added to the polymerization system at a rate lower than the polymerization rate of the vinyl monomer. A way to do that has been proposed. Further, Japanese Patent Application Laid-Open No. 58-1
According to Japanese Patent No. 62616, a maleimide monomer is supplied at a rate lower than the consumption rate of the vinyl monomer to a polymerization system charged with a vinyl monomer mainly composed of an aromatic vinyl monomer. , A method of copolymerizing has been proposed. Further, according to JP-A-2-51514, in order to obtain a specific maleimide-based copolymer, a charge ratio to a polymerization system, a use ratio of a solvent, a polymerization conversion rate, and the like are controlled within a specific range and a maleimide-based copolymer is obtained. A method of providing an aging step after completion of the dropping of the system monomer is disclosed.

[0004]

According to these methods, it is difficult to obtain a copolymer containing a maleimide monomer unit and an aromatic vinyl monomer unit in a molar ratio of 1: 1. The content of the maleimide monomer unit in the copolymer changes with the progress of the reaction, and eventually the content of the maleimide monomer unit increases from the molecule rich in the aromatic vinyl monomer unit. Thus, a copolymer having a wide distribution up to a certain molecule is obtained, and the ratio of the molecule in which the content of the maleimide monomer unit is almost equal to the average value is extremely low. Such a copolymer does not satisfy all of heat resistance, moldability and impact resistance.

Accordingly, an object of the present invention is to provide a maleimide-based copolymer which is excellent in heat resistance and impact resistance and has good melt moldability.

[0006]

In order to solve the above problems, the present invention provides an aromatic vinyl monomer unit (A) 8
0.0-40.0wt%, maleimide monomer unit (B)
20.0 to 60.0 wt%, and 0 to 30.0 wt% of monomer units (C) copolymerizable therewith (provided that
(Total amount of (A), (B) and (C) 100.0 wt%)
And at least 95 wt% of a molecule having a maleimide monomer unit (B) content of not more than 10% above and below the average value.

In the maleimide copolymer, the aromatic vinyl monomer unit (A) is composed of the aromatic vinyl monomer (a) and the maleimide monomer unit (B) is composed of the maleimide monomer. From (b), the monomer unit (C) is derived from the monomer (c) copolymerizable with the monomers (a) and (b), respectively. The ratio of the monomer units (A), (B) and (C) is such that the monomer unit (A) is 80.0 to 40.0 wt% and the monomer unit (B) is 20.0 to 60.0 wt%. , Monomer unit (C)
0 to 30.0 wt% (however, monomer units (A) to (C)
(A total amount of 100.0 wt%). When the ratio of the monomer unit (A) exceeds the above range, there is a problem that heat resistance is lowered and compatibility when blended with the thermoplastic resin is lowered. If the ratio is lower than the above range, processability and impact resistance are lowered. There is a problem. When the ratio of the monomer unit (B) is more than the above range, there is a problem that the molding processability is deteriorated and the impact resistance is lowered. When the ratio is less than the above, the maleimide-based copolymer has sufficient heat resistance to the resin composition. There is a problem that it cannot be given. When the ratio of the monomer unit (C) exceeds 30.0% by weight, there is a problem that it is difficult to obtain a balance of physical properties such as workability and impact resistance.

The maleimide copolymer of the present invention has a maleimide monomer unit (B) content of 45.0.
It is also possible to use a compound containing 95% by weight or more of a molecule in the range of ６60.0% by weight and within 10% of the average value. The sequence of the monomer units (A), (B) and (C) may be random or may contain a block portion.

In the maleimide-based copolymer of the present invention, the content of the maleimide-based monomer unit (B) is 10% above and below the average value.
% Or less of 95% by weight of molecules. If it is less than 95% by weight, all of heat resistance, moldability and impact resistance cannot be satisfied. The content of such a specific molecule may be determined directly by measurement, or indirectly as follows. For example, during the period from the start of the polymerization of the copolymer to the steady state until the end thereof, every minute time, the molar ratio of the aromatic vinyl monomer and the maleimide monomer in the reaction system was measured. The molar ratio of the aromatic vinyl monomer / maleimide monomer is from 2 to 200 at each time interval.
And the content of the maleimide monomer unit (B) in the produced copolymer is measured so as to fall within the range of 20% above and below the expected value. When the content of the system monomer unit (B) is 20.0 to 60.0
By gradually supplying the total amount of the maleimide-based monomer and the remaining amount of the aromatic vinyl-based monomer to the reaction system so as to be within the range of wt% and within 10% of the average value. The obtained maleimide-based copolymer can be regarded as containing 95% by weight or more of molecules in which the content of the maleimide-based monomer unit (B) is within 10% above and below the average value. When a maleimide-based copolymer having a maleimide-based monomer unit (B) content of 20.0 to 55.0% by weight is prepared, the molar ratio of aromatic vinyl monomer / maleimide-based monomer is as follows. , 2 to 200, and more preferably 10% or less of the expected value. Here, the minute time interval means, for example, a time for producing 1% of the maleimide-based copolymer, which varies depending on the reaction conditions.
It is sufficient to confirm the change in composition at this interval.However, in the present invention, the reaction is performed so that the monomer concentration ratio and the polymerization temperature are kept substantially constant from the start to the end of the polymerization. Since the conditions can be determined, it can be replaced at 0.5 to 1 hour intervals. Then, once the reaction conditions are set at such time intervals, the reaction may be performed so as to maintain the set reaction conditions without measuring the content each time. Molecules occupying less than 5% by weight of the copolymer may have a maleimide monomer unit (B) content of more than 10% above and below the average value. Here, the term “gradual supply” refers to, for example, continuous or intermittent supply of the supplied material, instead of supplying the entire amount at once, and usually means dropping.

The maleimide copolymer of the present invention generally has a weight average molecular weight of 50,000 to 1,000,000, a number average molecular weight of 20,000 to 300,000, and a viscosity at a temperature of 240 ° C. of 20,000 to 20,000.
1,000,000 cps, glass transition temperature 130-2
It has physical properties of 10 ° C and a glass transition temperature range of 5 to 15 ° C. The glass transition temperature range is defined, for example, as follows. The glass transition temperature (Tg) of the copolymer was measured by DSC (differential scanning calorimetry), and as shown in FIG. 3, two glass transition temperatures determined before and after Tg by shifting the baselines D and E of the differential heat curve. When the temperature at which the tangent F of the curve at the midpoint between the base line (parallel or non-parallel) intersects is Tg ₁ , Tg ₂ (° C.) (where Tg ₁
> Tg ₂ ), and the glass transition temperature range is Tg ₁ −Tg
₂ (° C). Among these physical properties, the fact that the glass transition temperature width is in the narrow range as described above indicates that the maleimide-based copolymer of the present invention has a much narrower composition distribution than the conventional one.

The maleimide monomer (b) used in the present invention is:

[0012]

Embedded image

A compound represented by, for example, maleimide, N-methylmaleimide, N-ethylmaleimide,
N-propylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-isobutylmaleimide, N-tert-butylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-chlorophenylmaleimide, N-methylphenylmaleimide,
N-bromophenylmaleimide, N-naphthylmaleimide, N-laurylmaleimide, 2-hydroxyethylmaleimide, N-hydroxyphenylmaleimide, N-methoxyphenylmaleimide, N-carboxyphenylmaleimide, N-nitrophenylmaleimide, and the like. And one or more of these can be used.

The aromatic vinyl monomer (a) used in the present invention is:

[0015]

Embedded image

A compound represented by the following formula: styrene; o-methylstyrene, m-methylstyrene, p-methylstyrene;
Methylstyrene (o-, m-, p-methylstyrene is also called vinyltoluene), 1,3-dimethylstyrene,
2,4-dimethylstyrene, ethylstyrene, p-third
Alkylstyrenes such as normal butylstyrene; α-methylstyrene, α-ethylstyrene, α-methyl-p-methylstyrene; vinylnaphthalene; o-chlorostyrene;
halogenated styrenes such as m-chlorostyrene, p-chlorostyrene, and 2,4-dibromostyrene; halogenated alkylstyrenes such as 2-methyl-4-chlorostyrene, and the like. The above can be used. From the viewpoint of the balance between productivity and physical properties, particularly, styrene, vinyltoluene and α-
It is desirable to use at least one selected from the group consisting of methylstyrene. Note that, if an aliphatic vinyl monomer is used without using an aromatic vinyl monomer, the reactivity of the monomer is low, and the heat resistance of the obtained copolymer is low,
In addition, there is a problem that hygroscopicity is large.

The monomer (c) is a compound having an ethylenically unsaturated bond other than the aromatic vinyl monomer (a) and the maleimide monomer (b). It is used for the purpose of improving solvent resistance and compatibility. Examples of the monomer (c) include unsaturated nitriles such as acrylonitrile, methacrylonitrile, ethacrylonitrile, and phenylacrylonitrile; and an alkyl group having 1 to 18 carbon atoms including a cycloalkyl group and a benzyl group ( (Meth) acrylic acid esters (eg, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, tertiary butyl (meth) acrylate,
Amyl (meth) acrylate, isoamyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate,
Lauryl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate); olefins such as ethylene, propylene, isobutylene and diisobutylene; dienes such as butadiene and isoprene; vinyl chloride, vinylidene chloride; Vinyl halides such as vinyl bromide and vinyl fluoride; vinyl ethers such as methyl vinyl ether and butyl vinyl ether; vinyl acetate;
Vinyl esters of saturated monocarboxylic acids such as vinyl propionate; allyl esters or methallyl esters of saturated aliphatic monocarboxylic acids such as allyl acetate and allyl propionate; ethylene glycol di (meth) acrylate, diethylene glycol di (meth) Acrylate, divinylbenzene, diallyl phthalate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, di (meth) acrylate of bisphenol A ethylene oxide or propylene oxide adduct Di (meth) acrylate of ethylene oxide or propylene oxide adduct of halogenated bisphenol A, tri (meth) acrylate of isocyanurate (Meth) acrylates such as di- or tri (meth) acrylates of ethylene oxide or propylene oxide adducts of polyisocyanate and isocyanurate; polyvalent acrylates such as triallyl isocyanurate; glycidyl (meth) acrylate; allyl glycidyl Ether, (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid or their half-esterified compounds and the like are used. One or more kinds are used depending on the purpose. The selection may be made without departing from the object of the invention. The amount of the monomer (c) to be used is preferably 0 to 30% by weight, more preferably 0 to 20% by weight, based on the total amount of the monomers used. Monomer (c)
If the amount used is more than the above range, the amount remaining as unreacted components may increase.

In order to obtain the maleimide copolymer of the present invention, 10 to 80% by weight of the total amount of the aromatic vinyl monomer is charged into the reaction system in advance, and the aromatic content in the reaction system after the initiation of the polymerization is measured. The maleimide monomer is added to the reaction system such that the molar ratio of the group III vinyl monomer / maleimide monomer is in the range of 2 to 200 and within 20% of the expected value. It is preferable to carry out the polymerization while gradually supplying the whole amount and the remaining amount of the aromatic vinyl monomer.

That is, the polymerization is preferably carried out as follows. 10 to 80% by weight of the total amount of the aromatic vinyl monomer (a) used in the reaction system such as a reaction vessel is charged. The total amount of the maleimide monomer (b) and the remaining amount of the aromatic vinyl monomer (a) are gradually supplied to the reaction system. At this time, the molar ratio of the aromatic vinyl monomer (a) / maleimide monomer (b) in the reaction system is in the range of 2 to 200, and is always within 20% of the expected value. It supplies like this. As a result, the desired maleimide-based copolymer can be obtained. The molar ratio (a) / (b) is different from the composition of the obtained copolymer due to the copolymerizability of the aromatic vinyl monomer (a) and the maleimide monomer (b) under the reaction conditions. Has a molar ratio (a) / (b) of 2
When the molecular weight is smaller than the above, an alternating copolymer is easily obtained. When the molecular weight exceeds 200, the content of the maleimide monomer unit (B) in the copolymer becomes too low to obtain the desired copolymer. I can't. The amount of the aromatic vinyl monomer (a) charged into the reaction system before the start of polymerization is 10% by weight of the total amount.
If it is less than 3, the molar ratio (a) / (b) tends to be smaller than 2 because the ratio of the unreacted aromatic vinyl monomer is too low. Since the concentration of the unreacted aromatic vinyl monomer in the reaction system increases as the initial charge amount of the aromatic vinyl monomer (a) increases, the supply rate of the maleimide monomer (b) Can be operated to maintain the value of the molar ratio (a) / (b) at 200 or less, but the initial charge of the aromatic vinyl monomer (a) is 80 wt% of the total amount. When the amount exceeds the above, the proportion of the maleimide-based monomer (b) in the dropping solution becomes large and the supply speed of the maleimide-based monomer (b) becomes too fast, so that the calorific value in the initial polymerization becomes large. . For this reason, in industrial production, an excessive cooling capacity is required, and the adjustment of the internal temperature at the start of polymerization becomes complicated.

In this polymerization step, the value of the molar ratio (a) / (b) is 2 to 2 at each minute time interval, as described above, after the start of the polymerization, that is, from the steady state to the end. It is controlled so as to be within the range of 200 and within 20% of the expected value. If it exceeds 20%, the composition of the obtained copolymer fluctuates with time, the composition distribution and the molecular weight distribution are widened, and the heat resistance, moldability and impact resistance are undesirably reduced.

The above-mentioned steady state means that, for example, the concentration of the maleimide monomer in the reaction system gradually increases after the initiation of polymerization,
It refers to the point in time when the fluctuation in the concentration shows a substantially constant tendency, preferably the point in time when it maintains a substantially constant value. Therefore, in the present invention, the composition of the formed copolymer is analyzed by sampling every minute time as described above, and the result is indicated by the time when the average value becomes ± 10%. Although such time varies depending on the reaction conditions, for example, after the start of monomer supply such as dropping, the polymerization conversion rate is 2 to 5 times.
%.

In the present invention, the polymerization is carried out in the presence of an organic solvent in the reaction system, and the polymerization is carried out in a boiling state. Is good. For example, while monitoring the temperature of the reaction system, the rate of dropping at least one of the aromatic vinyl monomer, the organic solvent, and the maleimide monomer can be more controlled. By changing the pressure of the reaction system, the boiling point can be maintained. Further, heat removal is facilitated, and a runaway reaction is prevented. Here, the boiling point is the boiling point of the mixture in the reaction system. However, since the aromatic vinyl monomer and the organic solvent used as required are predominantly present, the aromatic vinyl monomer It can be regarded as the azeotropic point between the body and the organic solvent.

The desired value of the molar ratio (a) / (b) in the present invention can be predicted from the maleimide copolymer and the copolymerizability ratio of each monomer, but is preferably at each polymerization condition. Will be confirmed. In the reaction system, only the aromatic vinyl monomer (a) may be charged, or the monomer (a) and an organic solvent may be charged as needed. In this case, the amount of the organic solvent is, for example, 0.5 to 20 times the weight of the aromatic vinyl monomer.

The method of dropping the aromatic vinyl monomer and the maleimide monomer is not particularly limited. For example, the maleimide monomer and the aromatic vinyl monomer may be dropped separately or mixed. Alternatively, a method of dissolving or dispersing a maleimide-based monomer in an aromatic vinyl-based monomer or an organic solvent and dropping it may be used. The ratio of the aromatic vinyl monomer to the maleimide monomer to be dropped is, for example, 80 to 20 wt% of the aromatic vinyl monomer and 80 to 20 wt% of the maleimide monomer. When an organic solvent is used, the amount of the organic solvent is, for example, 0 to 50% by weight based on the weight of all the monomers in the dropping solution.

In order to obtain a maleimide copolymer having a maleimide monomer unit (B) content of 45.0 to 60.0 wt%, an organic solvent / (organic solvent + aromatic solvent) in the reaction system is required. (Vinyl-based monomer) is 0.40 to 0.9.
It is preferable to add an organic solvent so as to give a value of 8. If the weight ratio is less than 0.40, the solution viscosity of the reaction system may increase, or the composition distribution may be widened due to poor stirring. Since the ratio becomes low, the reaction rate may decrease.

As the organic solvent, for example, toluene,
Aromatic solvents such as xylene and ethylbenzene; ketones such as methyl ethyl ketone (abbreviated as MEK), methyl isobutyl ketone and cyclohexanone; and polar solvents such as dimethylformamide, dimethylacetamide and dimethylsulfoxide are used. The use of organic solvents
For example, it is carried out for the purpose of increasing the solubility of the maleimide-based copolymer, and preventing the viscosity of the reaction solution from decreasing and the gel effect during the polymerization.

In the present invention, the addition of the copolymerizable monomer (c) may be carried out if the ratio of the concentration of the maleimide monomer to the aromatic vinyl monomer in the reaction system is kept constant. The method is not particularly limited. If the allocation between the initial preparation and the dropping is set in consideration of the copolymerizability of the monomer (c) to be used, it can be uniformly present in the copolymer. In the present invention, a polymerization initiator, a chain transfer agent and the like may be present in the reaction system. As the polymerization initiator, for example, 1,
1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, di-t-butyl peroxide, benzoyl peroxide, lauroyl peroxide, t-butylperoxyacetate, t-butylperoxyisobuty Peroxides such as tert-butylperoxypivalate, t-butylperoxy-2-ethylhexanoate, t-butylperoxylaurate, t-butylperoxybenzoate, and t-butylperoxyisopropyl carbonate Azobisisobutyronitrile, azobisdimethylvaleronitrile, azobis-
A compound usually used for polymerization of a maleimide monomer and an aromatic vinyl monomer, such as an azo compound such as 1-cyclohexanecarbonitrile, is used in a usual amount. The polymerization initiator may be charged in its entirety in the reaction system in advance, or may be supplied during the reaction.

The present invention can employ, for example, polymerization methods such as solution polymerization, bulk polymerization and emulsion polymerization, and are particularly effective in solution polymerization. The polymerization is carried out, for example, at a temperature of 60 to 200 ° C. for 1 to 20 hours. The polymerization conversion of all the monomers put in the reaction system is, for example, 50 to 100.
It is preferable that the content be wt%. After the completion of the dropping, that is, immediately after the completion of the polymerization, the mixture is cooled immediately, the reaction solution is added to a solvent such as methanol to precipitate a polymer, and after filtration and separation, the solvent and the like are removed by vacuum drying or the like. Can be obtained.

The maleimide copolymer of the present invention has good moldability and excellent heat resistance and impact resistance. Further, the ABS resin (acrylonitrile-butadiene-styrene resin) and MBS resin (methyl methacrylate-butadiene- It is also excellent in miscibility with rubber-modified resins such as styrene resins. Therefore, by blending the maleimide-based copolymer of the present invention with a rubber-modified resin, a heat-resistant impact-resistant resin having a high heat deformation temperature and a high impact resistance can be produced. When blending the maleimide-based copolymer of the present invention with a rubber-modified resin, using a device such as a twin-screw extruder, under normal operating conditions, the maleimide-based copolymer is 10 to 100 parts by weight based on 100 parts by weight of the rubber-modified resin. Blend in parts by weight. Further, the maleimide-based copolymer of the present invention has high heat resistance and excellent moldability (fluidity), and thus can be used as a modifier. For example, methyl methacrylate resin, methyl methacrylate-styrene resin, polycarbonate resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyphenylene oxide resin, vinyl chloride resin, chlorinated vinyl chloride resin, acrylonitrile-styrene resin, acrylonitrile-methyl methacrylate resin, styrene −
When used as a modifier such as a methacrylic acid resin, a styrene-methacrylic acid-acrylonitrile resin, and an unsaturated polyester resin, heat resistance is improved. In particular, it has excellent miscibility with crystalline resins such as polyamide resin, polyethylene terephthalate resin, and polybutylene terephthalate resin, and has improved heat resistance without impairing the characteristics of these resins, and can also improve moldability. preferable. When used as a modifier as described above, using a device such as a twin-screw extruder under normal operating conditions, 100 parts by weight of the above-described modified resin and maleimide copolymer 10
-100 parts by weight.

[0030]

[Function] The copolymerization of an aromatic vinyl monomer and a maleimide monomer proceeds very quickly, and has a strong alternating copolymerizability, so that a maleimide copolymer having an arbitrary composition can be obtained. Requires a large excess of an aromatic vinyl monomer. However, in such a method, the dripping of the maleimide-based monomer causes a large change in the concentration of the aromatic vinyl-based monomer, and the composition and the molecular weight distribution are likely to be wide. Accordingly, the maleimide monomer and the remaining aromatic vinyl monomer are gradually supplied to the reaction system in which the aromatic vinyl monomer is present at a specific ratio (or concentration), whereby the supplied maleimide monomer is supplied. Most of the monomer is consumed for copolymerization with the aromatic vinyl monomer, and the maleimide monomer is constantly present at a low concentration,
The consumed aromatic vinyl monomer is replenished. Thereby, the ratio in the reaction system of the aromatic vinyl monomer and the maleimide monomer can be set within the above specific range.

A maleimide-based copolymer containing 95% by weight or more of a molecule in which the content of the maleimide-based monomer unit (B) is within 10% above and below the average value is a glass transition temperature (Tg) which is an index of heat resistance. In addition, the melt flow rate (MFR), which is an index of workability, is improved.

[0032]

EXAMPLES Specific examples and comparative examples of the present invention will be shown below, but the present invention is not limited to the following examples.
In the following, "parts" means "parts by weight" and "%" means "wt%".
Respectively. Tables 1 and 2 collectively show the raw material compositions, the charging ratio of styrene, the polymerization temperature, and the polymerization time of Examples 1 to 8 and Comparative Examples 1 to 4. The charge ratio of styrene is the weight percentage of the amount charged to the reaction system with respect to the total amount of styrene.

Example 1 A polymerization vessel equipped with a condenser, a stirrer and a dropping funnel was charged with the initially charged raw material mixture having the composition shown in Table 1.
It was sufficiently dissolved and the inside was replaced with nitrogen. The temperature inside the polymerization vessel was raised to 80 ° C., and a dropping raw material mixture having the composition shown in Table 1 was dropped uniformly over 4 hours. The polymerization initiator is t-
Butylperoxy-2-ethylhexanoate
9 parts by weight were used. During the dropping, the reaction solution was sampled every 5 minutes, the amounts of unreacted styrene and unreacted maleimide in the reaction solution were analyzed by gas chromatography, and the molar ratio of unreacted styrene / unreacted maleimide (a) / (b) )
I asked. This molar ratio (a) / (b) is the expected value (18
The dropping speed or the dropping amount was adjusted so as to be within 20% (148 to 222) above and below 5). That is, the same dropping amount and dropping speed were maintained except that the dropping rate of the monomer was reduced when the molar ratio approached the lower limit of this range, and the dropping rate was increased when approaching the upper limit. After completion of the dropwise addition, the mixture was immediately cooled to obtain a pale yellow viscous final reaction solution. The final reaction solution was dropped into a large amount of methanol, and the precipitated solid was separated by filtration, washed, and dried to obtain a white copolymer.
The glass transition temperature width of this polymer was 9 ° C.

The polymerization rates of styrene and phenylmaleimide are 51.2% and 94.7%, respectively, based on the total amount.
The average content of styrene units and phenylmaleimide units in the copolymer determined by elemental analysis was 75.
5% and 24.5%. FIG. 1 shows the fluctuation of the molar ratio of unreacted styrene / unreacted phenylmaleimide every 5 minutes from the start of the dropping to the end of the dropping. In FIG. 1, M ₁ is a desired value of the molar ratio, M ₂ is a value 20% below the desired value, and M ₃ is a value 20% above the desired value. FIG. 2 shows the variation in the content of the maleimide monomer unit (B) in the copolymer obtained at each sampling. The ratio of the maleimide-based monomer units (B) in the copolymer formed during the minute time interval (here, 5 minutes) depends on the supply amount of each monomer up to the time of sampling and each monomer at the time of sampling. Of each monomer from the difference from the abundance of Y (a), Y (b)
And the consumption of each monomer after 5 minutes obtained in the same manner as Y ′ (a) and Y ′ (b),

[0035]

(Equation 1)

Is represented by Time to steady-state reaction is 10
The amount of the copolymer formed until the steady state reaction was reached was 3.4% of the total. Examples 2 and 3 In Example 1, the raw material composition, the polymerization temperature and the polymerization time were changed as shown in Table 1, and the expected values of the molar ratio (a) / (b) are shown in Table 3. The polymerization was carried out in the same manner as in Example 1, except that the reaction liquid was sampled every hour instead of every 5 minutes during the dropping, to obtain a copolymer.

Example 4 In Example 1, the raw material composition, the polymerization temperature and the polymerization time were changed as shown in Table 1, and the expected values of the molar ratio (a) / (b) are shown in Table 3. Polymerization was carried out in the same manner as in Example 1 except that the polymerization temperature was changed to the boiling point (90 ° C.) of the mixture in the reaction system, and the amount of dropwise addition was adjusted. A polymer was obtained. When the temperature of the reaction solution was measured continuously using a platinum resistor during the dropping, the temperature change was ± 0.5 ° C. or less.

Examples 5 to 7 In Example 4, the raw material composition, the polymerization temperature and the polymerization time were changed as shown in Tables 1 and 2, and the desired molar ratio (a) / (b) was obtained. Polymerization was carried out in the same manner as in Example 4 except that the values were changed as shown in Tables 3 and 4, to obtain a copolymer. However, in Example 6, the polymerization initiator was 0.1 g of t-butyl peroxyisopropyl carbonate.
Polymerization was carried out by changing to 04 parts by weight. The glass transition temperature range of the polymer obtained in Example 7 was 9 ° C.

Comparative Example 1 In Example 1, the raw material composition, the polymerization temperature and the polymerization time were changed as shown in Table 2, and the molar ratio (a) /
Except that the expected value of (b) was changed as shown in Table 4,
Polymerization was carried out in the same manner as in Example 1 to obtain a copolymer. The glass transition temperature width of this polymer was 17 ° C. FIG. 1 shows the fluctuation of the molar ratio (a) / (b) of unreacted styrene / unreacted phenylmaleimide every 5 minutes from the start of the dropping to the end of the dropping. In FIG. 1, N ₁ is the expected value of the molar ratio, N ₂ is the value 20% below the expected value, and N ₃ is 2% above the expected value.
The value is 0%. FIG. 2 shows the variation of the maleimide monomer unit in the copolymer obtained at each sampling. As is clear from FIG. 2, the concentration of each monomer in the reaction system continued to change, and there was no time that could be regarded as a steady state.

Comparative Examples 2 and 3 In Example 1, the raw material composition, the polymerization temperature and the polymerization time were changed as shown in Table 2, and the expected values of the molar ratio (a) / (b) were as shown in Table 4. In the same manner as in Example 1, except that the reaction liquid was sampled every hour instead of every 5 minutes during the dropping, and that the dropping rate and the dropping amount were not adjusted during the dropping, The polymerization was carried out to obtain a copolymer.

Comparative Example 4 The procedure of Example 4 was repeated, except that the bath temperature was kept at 95 ° C. after the completion of the dropwise addition, and the polymerization was further carried out for 1 hour.
Polymerization was carried out in the same manner as in the above to obtain a copolymer. In the above Examples and Comparative Examples, the molar ratio of unreacted styrene / unreacted phenylmaleimide every hour from the start of the dropping (a)
/ (B), the desired value of the molar ratio and the upper and lower
% Are shown in Tables 3 and 4, and the content of the maleimide monomer unit (B) in the copolymer produced per unit time and the polymerization conversion per hour are shown in Tables 5 and 6. .

The unreacted styrene, unreacted phenylmaleimide, unreacted acrylonitrile, and solvent in each final reaction solution in the above Examples and Comparative Examples were examined by gas chromatography, and the composition of the copolymer was determined by elemental analysis. . The results are shown in Tables 7 and 8. The average content of each monomer unit of each maleimide-based copolymer obtained in the above Examples and Comparative Examples, and the content of the maleimide-based monomer unit within 10% above and below the average value of the molecules The contents are shown in Tables 7 and 8. Table 9 shows the time required to reach the steady state and the proportion of the copolymer formed during this time to the total formed copolymer.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

[Table 4]

[0047]

[Table 5]

[0048]

[Table 6]

[0049]

[Table 7]

[0050]

[Table 8]

[0051]

[Table 9]

As can be seen from Tables 1 to 9, the copolymers of the examples were uniform with little change in the maleimide monomer unit in each sampling during the polymerization reaction. In contrast,
During the polymerization reaction, the copolymer of the comparative example had a monomer molar ratio (a)
/ (B) changed greatly, and the copolymer composition was non-uniform. Weight average molecular weight and number average molecular weight of the copolymers obtained in the above Examples and Comparative Examples, glass transition temperature, M
The FR was examined, and the results are shown in Table 10.

The weight average molecular weight and number average molecular weight were calculated from an elution curve of gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent, based on a standard polymer of polystyrene. The glass transition temperature was measured using DSC-8230 manufactured by Rigaku Denki Co., Ltd. under a nitrogen stream and using α-alumina as a reference.
Inflection point determined by the tangent method from the DSC curve measured in minutes.

The MFR was measured at a temperature shown in Table 10 using a Shimadzu flow tester CFT-500 according to JIS-K7210.

[0055]

[Table 10]

As shown in Table 10, the copolymers of the examples had a high glass transition temperature and a high MFR. On the other hand, the copolymer of the comparative example had a low glass transition temperature and a low MFR for the constituent ratio of the maleimide-based monomer. -Reference Examples 1 to 12- The maleimide-based copolymers and polyamide resins (Amilan 1071 manufactured by Toray Industries, Inc.) obtained in Examples 1 to 7 and Comparative Examples 1 to 4 were sufficiently mixed in the composition shown in Table 10. After kneading, a molded plate is prepared from this kneaded material, and the heat deformation temperature,
The impact resistance and moldability were examined, and the results are shown in Table 11.

The heat distortion temperature was measured under a load of 18.5 kgf / cm ² based on JIS-K7207. Impact resistance is J
The Izod impact strength was measured using a 40 kgf · cm hammer based on IS-K7110. The moldability was evaluated by visually observing the fluidity of the obtained composition and the appearance of the molded article. The evaluation criteria are as follows:
× indicates failure.

A: There is surface gloss. …: Slight sink marks (circular depressions, also referred to as sync marks). Δ: There are many sink marks. X: A molded body cannot be formed.

[0059]

[Table 11]

As shown in Table 11, when the copolymers of the examples were used, the balance between the heat distortion temperature, the impact resistance and the moldability was excellent. On the other hand, when the copolymer of Comparative Example was used, the balance between the heat resistance and the impact resistance was poor, and the moldability was reduced.

[0061]

According to the present invention, a maleimide copolymer having excellent heat resistance and impact resistance and good melt moldability is provided.

[Brief description of the drawings]

FIG. 1 is a graph showing the variation of the monomer molar ratio (a) / (b) in a reaction solution with the lapse of polymerization time in Example 1 and Comparative Example 1.

FIG. 2 is a graph showing the variation of the content of a maleimide monomer unit in a maleimide copolymer produced every 5 minutes with the lapse of polymerization time in Example 1 and Comparative Example 1.

FIG. 3 is a differential thermal curve of the copolymer by DSC.

[Explanation of symbols]

M ₁ expected value of molar ratio M ₂ value of 20% below expected value M ₃ value of 20% above expected value

Claims (2)

[Claims] 1. An aromatic vinyl monomer unit (A)
0-40.0 wt%, maleimide monomer unit (B) 2
0.0 to 60.0 wt%, and 0 to 30.0 wt% of monomer units (C) copolymerizable therewith (provided that (A),
(B) and (C) in a total amount of 100.0% by weight), and a maleimide-based copolymer containing 95% by weight or more of molecules having a maleimide-based monomer unit (B) content within 10% above and below the average value. Coalescing. 2. The maleimide copolymer according to claim 1, wherein the content of the maleimide monomer unit (B) is 45.0 to 60.0 wt%.