JPH0656921A - Production of imidized copolymer - Google Patents

Abstract

PURPOSE:To produce an imidized copolymer having a high impact resistance without decreasing the mol.wt. in the imidizing step by mixing a precursor of the copolymer with an imidizing agent under a specified shear rate in addition to the conventional imidizing conditions. CONSTITUTION:An imidized copolymer is produced in two steps: the first step wherein a precursor obtd. from maleic anhydride, a vinylarom. compd., and, if necessary, another ethylenically unsatd. compd. is imidized by mixing it with an imidizing agent in a mixing zone under a pressure of 10kg/cm<2> or higher, at 200-270 deg.C, and with a shear rate of 10-150sec<-1> for 2-5min; and the second step wherein the resulting product is transported from the mixing zone to an adjacent removal zone, where low-mol.-wt. impurities are removed under a reduced pressure.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION The present invention relates to a process for producing an imidized copolymer comprising maleimide or N-substituted maleimide, a vinyl aromatic compound, and optionally one or more other unsaturated compounds. Regarding

[0002]

2. Description of the Related Art Copolymers of maleic anhydride, vinyl aromatic compounds and other unsaturated compounds, especially maleic anhydride-styrene-acrylonitrile copolymer (SM
A resin) has a high heat distortion temperature and exhibits good heat resistance, and SMA resin is a styrene-acrylonitrile copolymer (AS resin) or a styrene-acrylonitrile-rubber elastic body graft copolymer (ABS resin). ) And the like have excellent compatibility. Therefore, the SMA resin is blended with the AS resin and / or the ABS resin and the like to improve the heat resistance and solvent resistance of the AS resin and the like. However, a blend resin of an SMA resin and an AS resin and / or an ABS resin, etc. causes coloring and foaming when heated at a high temperature, particularly at 230 ° C. or higher, and also exhibits a weight reduction and a crosslinking reaction. It is difficult to use as an injection molding material that needs to be heated to 230 ° C or higher. On the other hand, as a means for solving the above-mentioned problems, the present inventors have already kneaded the raw material copolymer with the imidizing agent under a high pressure for a predetermined time to imidize, thereby improving heat resistance and A method has been proposed for continuously and economically producing a high-molecular-weight imidized copolymer having high-temperature resistance stability in a single step in a non-aqueous system (Japanese Patent Laid-Open No. HEI-2).
-4806).

[0003]

[Outline of Invention]

[0004]

Means for Solving the Problems As a result of various test studies to solve the above-mentioned problems, the present inventors have found that in addition to the conditions described in the above-mentioned proposal (JP-A-2-4806),
When the kneading of the raw material copolymer and the imidizing agent was carried out while giving a shear rate of 10 sec ^-1 or more, it was found that the object of the present invention was effective, and the present invention was completed. .

<Summary> That is, the method for producing an imidized copolymer according to the present invention is characterized by carrying out the following first step and second step. First step: 10 kg / cm ^{2 of an} imidized precursor copolymer consisting of maleic anhydride, a vinyl aromatic compound and optionally other ethylenically unsaturated compound in a kneading zone.
The above pressure, the temperature of 200 ~ 270 ℃, 10 ~ 250 s
Kneading with an imidizing agent under a shear rate of ec ^-1 and a condition of 2 to 5 minutes to imidize the imidized precursor copolymer. Second step: a step of feeding the product of the first step to a removal zone communicating with the kneading zone to remove low-molecular contaminants under reduced pressure.

<Effect> According to the present invention, a high-molecular-weight imidized copolymer having heat resistance and high-temperature stability can be continuously and economically produced in a single step in a non-aqueous system, and the imidization ratio can be improved. It can be manufactured in a uniform and high state.

[Detailed Description of the Invention] <Imidized Precursor Copolymer> The precursor of the imidized copolymer to be imidized by the method according to the present invention includes maleic anhydride, a vinyl aromatic compound, and if necessary. And another ethylenically unsaturated compound. That is, the precursor copolymer to be imidized in the present invention is a copolymer of maleic anhydride and thus the "imide" is maleimide or N-substituted maleimide.

The comonomer of this precursor copolymer for maleic anhydride is a vinyl aromatic compound. The vinyl aromatic compound is typically styrene having a nucleus and / or a side chain substituted or unsubstituted. In this case, the substituent may be a lower alkyl group, a halogen atom, a lower alkoxy group, or the like. Such vinyl aromatic compounds include styrene, alpha-methylstyrene, vinyltoluene, ethylstyrene, isopropylstyrene, and mixtures thereof. The preferred vinyl aromatic compound in the present invention is styrene. This precursor copolymer may be a copolymer of, in addition to the above-mentioned two essential monomers, an ethylenically unsaturated monomer copolymerizable therewith. Such ethylenically unsaturated monomers include those other than the above-mentioned two kinds, for example, (meth) acrylic acid ester, (meth) acrylonitrile, vinyl ester, vinyl halide, and the like.

In the present invention, the imidized precursor copolymer to be imidized has a maleic anhydride content of 10% by weight or more.
The range of 40% by weight is preferable. If it is less than 10% by weight, one having high heat resistance cannot be expected, and if the raw material copolymer of less than 10% by weight does not have poor high-temperature stability, it has little meaning to imidize. When it exceeds, the heating and melting of the imidization precursor copolymer requires a considerably high temperature (in some cases, it becomes difficult in the temperature range of 200 ° C to 270 ° C), and an imidized product having a good color tone cannot be obtained. In addition, the imidization efficiency also decreases. The vinyl aromatic compound content is usually 90 to 60% by weight, preferably 90 to 70% by weight. When it is copolymerized, the content of the ethylenically unsaturated monomer used as necessary is usually 1 to 30% by weight, preferably 3 to 25% by weight. This copolymer is a solution, suspension, or emulsion polymerization of all or part of each monomer by a suitable polymerization initiation means such as decomposition of a radical polymerization initiator (thermal decomposition or redox decomposition). It can be manufactured according to the method.

<Imidizing Agent> The “imidizing agent” in the present invention is a compound which acts on the acid anhydride residue of maleic anhydride to convert it into an imide bond, which is ammonia or primary Or it is a secondary amine. The substituent forming a primary or secondary amine is an aliphatic (including alicyclic) or aromatic hydrocarbon residue or a derivative of these hydrocarbon residues having a substituent that does not hinder the imidization reaction. There is. The aliphatic hydrocarbon residue has 1 to 1 carbon atoms.
About 10 and preferably about 3 to 8 are common, and as the aromatic hydrocarbon residue, those having 6 to 12 carbon atoms, particularly preferably about 6 to 8 are common, which hinders the imidization reaction. As a substituent that does not affect, a halogen atom,
A nitro group, an alkoxy group, preferably a lower alkoxy group,
There are others.

Specific examples of imidizing agents suitable for use in the present invention include (a) ammonia, (b) aliphatic amines such as methylamine, ethylamine, n-propylamine, isopropylamine, butylamine, isobutyl. Amine, s-butylamine, 1,2-dimethylpropylamine, hexylamine, cyclohexylamine,
(C) aromatic amines such as octylamine and stearylamine, such as aniline, orthotoluidine, 2,4
There are 6-trichloroaniline, 4-nitro-2-toluidine, α-naphthylamine, β-naphthylamine, 2-methoxyaniline, 4-methoxyaniline, 2-ethoxyaniline, 4-ethoxyaniline and the like. These can be used in combination within each group and / or between groups, and can be used in the imidization reaction in the form of gas, solution such as aqueous solution or the like. When the imidizing agent is an amine, the resulting imide is an N-substituted imide.

[0012] These imidizing agents are
Maleic anhydride can be converted to the corresponding imide under the condition of applying pressure-shearing force, but an imidization catalyst can also be used if necessary. As the imidization catalyst,
Although any compound capable of promoting the reaction of converting an acid anhydride into the corresponding imide can be used, a representative group of such imidization catalysts are tertiary amines. Tertiary amines useful as imidization catalysts include trimethylamine, triethylamine, tripropylamine, N, N-
Examples include dimethylaniline and pyridine.

<Imidization (No. 1)> The imidization according to the present invention is carried out under the conditions of heating, pressurization and application of shearing force. Then, after this step (referred to as the first step), the imidization reaction product is subjected to reduced pressure conditions, and low molecular inclusions such as the imidizing agent used, the solvent or dispersion medium used, the by-product, and the like, Is carried out (second step).
In the first step of the present invention, the pressure for imidizing the imidization precursor copolymer is maintained at 10 kg / cm ² or more. In order to maintain the pressure within a predetermined value or range, the screw element is configured so that a pressure of 10 kg / cm ² or more is applied to the kneading zone of the extruder, and the pressure of charging the imidizing agent into this kneading zone. Should be maintained above 10 kg / cm ² . When the pressure is less than 10 kg / cm ² , the imidizing agent is vaporized in the kneading region and does not enter the molten precursor copolymer,
This is because the kneading efficiency is lowered and the desired imidization efficiency is not achieved.

In the first step of the present invention, the temperature at which the raw material copolymer is imidized is selected from the range of 200 ° C to 270 ° C. When the reaction temperature exceeds 270 ° C,
This is because the decrease in the molecular weight of the precursor copolymer becomes remarkable, and since the imidization reaction is reversible, the ratio of the reverse reaction increases, and the imidization efficiency decreases on the contrary. on the other hand,
If the temperature is lower than 200 ° C., the precursor copolymer may be insufficiently heated and melted, or even if melted, the viscosity is high and the kneading efficiency with the imidizing agent is lowered, and thus the desired imidization efficiency is lowered. Is not achieved.

In the first step of the present invention, the kneading conditions for imidizing the precursor copolymer are 10 sec ^-1 or more and 2
It is selected from the shear rate range of 50 sec ^-1 or less. When the raw material copolymer is melt-kneaded together with the imidizing agent in a state where the given shear rate does not reach 10 sec ^-1 , both are not uniformly kneaded, and thus the imidized copolymerized product is uniformly imidized. It is unavoidable that a part of the copolymer having a low imidization ratio is contained without obtaining a coalescence. The portion where imidization is not sufficiently performed naturally undergoes a decrease in molecular weight due to heat history during melt-kneading, so the resulting imidized copolymer cannot have a high uniform molecular weight, It contains a fairly low molecular weight copolymer moiety. The low imidization ratio / low molecular weight copolymer partially contained does not affect the high temperature resistance stability, but has a large effect on the impact strength of the blend resin with the ABS resin or the like. Therefore, it is difficult for the imidized copolymer imidized under a low shear rate condition to give a blend resin with an ABS resin or the like having high impact resistance. On the other hand, a shear rate of more than 250 sec ^-1 is also not preferable because it causes a decrease in the molecular weight of the copolymer due to the local heat generation by shearing. It is understood that having a high uniform molecular weight and an imide content is a particularly desirable property of the imidized copolymer according to the present invention and could not be achieved by conventional methods.
That is, in the imidized copolymer obtained by the present invention, most of the copolymer molecules have the same molecular weight and imide content, and as a result, a blended resin thereof with an ABS resin, In addition to high heat resistance and high temperature stability, it can also have high impact resistance. Also, the molecular weight of the imidized copolymer according to the present invention is very close to that of its precursor, maleic anhydride copolymer, which is a great advantage as compared with the conventional method that causes a decrease in the molecular weight. Is.

Another reaction condition for imidization according to the present invention, that is, a heating and kneading time is limited to 2 minutes or more and 5 minutes or less. If it exceeds 5 minutes, the molecular weight of the copolymer will decrease at a high temperature of 200 ° C. or more, and the production efficiency will decrease, while if it is less than 2 minutes, the kneading efficiency will decrease and a high imidization efficiency will not be achieved. The imidizing agent is used in an amount of 0.8 to 1 mol per maleic anhydride in the copolymer.
It is preferably 1.5 mol. In addition, during the imidization reaction or during the kneading in the rapid charging zone that is carried out as the preceding step (details of special mention), coloring or molecular weight reduction of the imidized copolymer produced or its precursor copolymer, etc. In order to prevent the deterioration of the above, a phenol-based stabilizer, a phosphorus-based stabilizer, and / or a sulfur-based stabilizer or the like can be used in combination as an antioxidant.

In the imidization according to the present invention, the precursor copolymer is imidized in the first step, and then the low molecular impurities are removed from the imidized copolymer in the second step. The method for removing the low-molecular contaminants can be carried out by using a usual technique depending on the types of byproducts, unreacted substances, etc. contained in the imidized copolymer. For example, it can be carried out by bringing the imidized copolymer into a molten state by a conventional venting method, applying a reduced pressure (including a vacuum) thereto, and further heating at the same time. When a vacuum is applied, the degree of vacuum can be set to, for example, 50 to 200 Torr.

<Imidization (No. 2)> FIG. 1 schematically shows an apparatus for carrying out the continuous process for producing an imidized copolymer according to the present invention. This device 1 is a co-rotating complete meshing twin-screw extruder, has a supply port 5 for an imidized precursor copolymer, and a premixing zone 6, and a kneading zone 3 contains an imidizing agent. Press-fitting pump 7
And an imidizing agent supply port 8 connected to the pump 7, and further, a desired imide is provided between the charging zone 2 and the kneading zone 3 and between the kneading zone 3 and the removal zone 4. Sealing elements 13 and 14 are provided for maintaining the activation pressure. The removal zone 4 has vent ports 9 and 1
0 is provided, and the vent port is connected to the vacuum pump 12 via the trap 11. A nozzle port (die) 15 is provided at the outlet of the removal zone 4.

In the imidization carried out by using such an apparatus, the imidized precursor copolymer is continuously or intermittently charged into a charging zone communicating with the kneading zone, and the charging zone is charged with the charging zone. Continuously or intermittently from the above to the kneading zone, kneading with the imidizing agent, and feeding the imidization reaction product thus obtained continuously or intermittently to the removal zone. It is usually done by a method.
The present invention can be implemented using various devices other than the above continuous device examples. For example, various extruders such as single-screw extruders, meshing twin-screw extruders, non-meshing twin-screw extruders, deforming screws and barrel type co-kneaders or non-screw type ram extruders, etc. And various batch-type devices. A preferred workable device is a co-rotating full mesh twin screw extruder. This is because the kneading effect is high, there is no stagnation (high self-cleaning property), uniform kneading is possible, and pressure is easily generated or maintained in the kneading region. The imidization according to the present invention can also be carried out by an apparatus in which the charging zone is omitted in the apparatus shown in FIG. That is, the imidization precursor copolymer is supplied to the kneading zone 3 separately from or together with the imidizing agent.

[0020]

EXAMPLES The following examples and comparative examples serve to explain the present invention more specifically. The present invention is not limited to the following examples unless it exceeds the gist.

Example 1 A total of 100 parts by weight of 88.9% by weight of styrene, 4.0% by weight of methyl methacrylate and 7.1% by weight of methyl ethyl ketone was placed in a completely mixed stirring reactor having an internal volume of 2 liters. , Di-tert-butylperoxyacetate 0.
The mixed solution added with 011 parts by weight was continuously fed at a rate of 2.0 kg / HR. At the same time, the same reactor was continuously fed with maleic anhydride monomer heated to about 70 ° C. at a rate of 0.4 kg / HR. The polymerization temperature was set to 150 ° C., the polymerization was allowed to proceed to a polymerization conversion rate of 65% by weight, and the polymerization reaction liquid was continuously taken out.

The polymerization reaction liquid continuously taken out was immediately sent to a devolatilization apparatus at 200 ° C./50 Torr to separate unreacted monomer and solvent and pelletized. As a result of analysis, the obtained pellets were a terpolymer of 69/26/5 with a composition of styrene / maleic anhydride / methyl methacrylate in wt%. As shown in FIG. 1, a 30 mm co-rotating, completely meshing twin screw extruder was used, and the imidization precursor copolymerization, which was the terpolymer obtained as described above, was added thereto at 5 kg / Supplied at a rate of HR. Most of the kneading zone of this extruder is composed of a kneading disk, and seal elements are attached to both ends thereof. The imidization extrusion conditions are a temperature of 250 ° C. and a shear rate of 50 s.
It was set so that ec ⁻¹ and the average residence time in the kneading zone were about 3 minutes.

The shear rate (S) here was determined according to the following equation. S = πDN / h D: Screw diameter N: Screw rotation speed h: Screw groove depth The average residence time in the kneading zone was measured by the method shown below. While extruding the raw material copolymer under a certain extrusion condition, a black or red colorant masterbatch was added from the supply port 5 of the copolymer pellets, and the imidizing agent supply port 8 and the first Observe the change in color of the molten polymer at the vent 9. The time at which coloring begins at each location and the time at which color development by the colorant completely disappears is T (8-start), T (8-end), T (9-
The average residence time R as
Calculate T. RT = {(T (9-start) -T (8-start)) + (T (9-
End) -T (8-end))} / 2

Aniline was used as the imidizing agent, and this was fed to the kneading zone from its feed port at a rate of 1.2 kg / HR. The discharge pressure of the aniline charging pump at this time is 12
It was kg / cm ² . A reduced pressure of about 100 torr was applied to both vents, and by-product water and unreacted aniline from the vents were separated and collected in a trap. The molten resin was extruded into a strand form from a nozzle, and this strand was cooled in a water tank and cut with a cutter to form a pellet. The obtained imidized copolymer had a 90% imidization yield as a result of quantitative analysis with an infrared spectrophotometer. The physical properties of the obtained imidized copolymer were as shown in Table 1. The resulting imidized copolymer and ABS resin with high impact resistance ("Tflex 710" manufactured by Monsanto Kasei Co., Ltd.)
(Acrylonitrile: 24%, butadiene: 21%, styrene: 55%, MFR: 8 g / 10 minutes (240 ° C / 1
0 kgf), VICAT: 90 ° C.)) in a weight ratio of 1/1 and compounded using a kneading 30 m / m co-rotating complete meshing twin screw extruder to give a heat resistant resin composition. Obtained. The physical properties of the above resin composition are
It was as shown in the table.

Example 2 An imide was prepared in the same manner as in Example ¹ except that the temperature was changed to 270 ° C. and the shear rate was changed to 30 sec ⁻¹ in the imidization extrusion conditions. A chemical copolymer and a heat resistant resin composition were produced. The imidized copolymer obtained had an imidization yield of 80%.
The physical properties of the obtained imidized copolymer are shown in Table 1, and the physical properties of the heat resistant resin composition are shown in Table 2.

Example 3 In the example described in Example 1, the shear rate was changed to 15 sec ^-1 in the imidization extrusion conditions, and aniline (the same amount as in the same example) was used as the imidizing agent, as well as imide. 0.5 part by weight (based on the maleic anhydride residue in the precursor copolymer) of N, N-dimethyldodecylamine (D
Except that MDA) is used,
An imidized copolymer and a heat resistant resin composition were produced.
The imidized copolymer obtained had an imidization yield of 95%. The physical properties of the imidized copolymer and heat-resistant resin composition obtained were as shown in Tables 1 and 2.

Comparative Example 1 In the example described in Example ¹ , except that the shear rate was changed to 8 sec ^-1 in the imidization extrusion conditions of the raw material copolymer.
An imidized copolymer and a heat resistant resin composition were produced in the same manner as in the same example. The imidized copolymer obtained had an imidization yield of 88%. Table 1 shows the physical properties of the imidized copolymer, and Table 2 shows the physical properties of the heat-resistant resin composition.
Shown in the table.

Comparative Example 2 In the example described in Example 2, the imidization copolymer and the heat resistance were the same as in the same example except that the shear rate was changed to 8 sec ^-1 in the imidization extrusion conditions. A resin composition was produced. The imidized copolymer obtained had an imidization yield of 81%. Table 1 shows the physical properties of the imidized copolymer, and Table 2 shows the physical properties of the heat resistant resin composition.

Comparative Example 3 In the example described in Example 3, except that the shear rate was changed to 8 sec ^-1 in the imidization extrusion conditions, the imidization copolymer and the heat resistance were the same as in the same example. A resin composition was produced. The imidized copolymer obtained had an imidization yield of 92%. Table 1 shows the physical properties of the imidized copolymer, and Table 2 shows the physical properties of the heat resistant resin composition.

[0030]

[Table 1]

[0031]

[Table 2]

As can be seen from Table 1, the imidized copolymer obtained by the production method of the present invention and the imidized copolymer obtained by the comparative example have physical properties as an imidized copolymer ( (Imidization yield, molecular weight, heat resistance) Almost no difference is observed. However, as can be seen from Table 2, the blended resin composition of the imidized copolymer and the ABS resin obtained by the production method of the present invention shows an excellent balance of physical properties, and particularly, in terms of IZOD impact strength and FDI. As described above, the blended resin composition of the imidized copolymer and the ABS resin obtained in Comparative Example is significantly inferior in impact resistance, while having high impact resistance.

The physical properties shown in Tables 1 and 2 were measured according to the following methods. 1) Molecular weight (weight average): gel permeation
Chromatography 2) VICAT (Vicat softening point): JIS K-7
206 3) Tensile strength: JIS K-7113 4) Tensile elongation: JIS K-7113 5) Bending strength: JIS K-7203 6) Bending modulus: JIS K-7203 7) IZOD impact strength: JIS K-7110 8) FDI (fall weight impact strength): JIS K-72119 9) HDTUL (heat distortion temperature / load deflection temperature): JI
SK-7202 10) MFR (melt flow rate): JIS K-7
210

[0034]

Industrial Applicability According to the present invention, a high-molecular-weight imidized copolymer having heat resistance and high temperature stability can be continuously and economically produced in one non-aqueous system.
As described above in the section “Summary of Invention”.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of an apparatus that can be used in the manufacturing method according to the present invention.

[Explanation of symbols]

 1 Equipment 2 Charge Zone 3 Kneading Zone 4 Removal Zone 5 Raw Material Copolymer Supply Port 6 Premixing Zone 7 Pump 7 8 Imidizing Agent Supply Port 9 Vent Port 10 Vent Port 11 Trap 13 Seal Element 14 Seal Element 15 Nozzle Port (Die)

Claims (3)

[Claims] 1. A method for producing an imidized copolymer, which comprises carrying out the following first step and second step. First step: 10 kg / cm ^{2 of an} imidized precursor copolymer consisting of maleic anhydride, a vinyl aromatic compound and optionally other ethylenically unsaturated compound in a kneading zone.
The above pressure, the temperature of 200 ~ 270 ℃, 10 ~ 250 s
Kneading with an imidizing agent under a shear rate of ec ^-1 and a condition of 2 to 5 minutes to imidize the imidized precursor copolymer. Second step: a step of feeding the product of the first step to a removal zone communicating with the kneading zone to remove low-molecular contaminants under reduced pressure. 2. An imidized precursor copolymer is continuously or intermittently charged into a charging zone communicating with the kneading zone, and this is continuously or intermittently fed to the kneading zone from the charging zone. The method for producing an imidized copolymer according to claim 1, wherein the imidized copolymer is fed and kneaded with the imidizing agent. 3. The method for producing an imidized copolymer according to claim 1, wherein the kneading in the kneading zone is performed by a co-rotating complete meshing twin screw extruder.