JPH0368043B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an efficient and novel method for producing maleimide copolymers having high heat distortion temperatures and high thermal decomposition temperatures. Maleimide copolymers have attracted attention for their high heat distortion temperature and excellent heat resistance, but the synthesis method for maleimide monomers such as N-phenylmaleimide used as starting materials is difficult. Since it is complicated and requires a dehydrating agent, a catalyst, a co-catalyst, etc. during synthesis, it has the disadvantage that it is difficult to obtain the desired maleimide copolymer at a low cost. In response to this, studies have been conducted on a method for producing maleimide copolymers without using maleimide monomers as starting materials, and
-39651 and JP-A-57-55901 disclose a method for producing a maleimide copolymer by reacting a copolymer containing maleic anhydride with ammonia or a primary amine. Proposed. However, since this method consists of a ring-opening reaction of maleic anhydride units and an imide ring-closing reaction, it not only takes a long time for the reaction but also makes it difficult to complete the imide ring-closing. There is a drawback that thermal stability during molding cannot be fully satisfied. Therefore, the present inventors conducted intensive studies with the aim of efficiently producing a maleimide copolymer having a high heat distortion temperature and thermal decomposition temperature. By reacting acid ester compounds,
The inventors have discovered that the above object can be effectively achieved and have arrived at the present invention. That is, in the present invention, a vinyl copolymer or a rubber-modified vinyl copolymer containing 5 to 50 mol% of maleic anhydride is prepared in a non-aqueous organic solvent.
The present invention provides a method for producing a maleimide copolymer, which comprises imidizing the copolymer by reacting it with an isocyanate ester compound in an amount equivalent to or more than the maleic anhydride contained in the copolymer. The vinyl copolymer or rubber-modified vinyl copolymer (hereinafter abbreviated as copolymer (A)) containing maleic anhydride used as a starting material in the present invention refers to maleic anhydride and a copolymer thereof. A copolymer obtained by copolymerizing other possible vinyl monomers or copolymerizing in the presence of a rubbery polymer, and containing maleic anhydride units of the following formula [] It is something to do. Other vinyl monomers that can be copolymerized with maleic anhydride include aromatic vinyl monomers such as styrene and α-methylstyrene, and (meth)acrylic acids such as methyl methacrylate and methyl acrylate. Examples include ester monomers and vinyl cyanide monomers such as acrylonitrile and methacrylonitrile, and two or more of these can be used in combination. In addition, as rubber-like polymers for modification, polybutadiene rubber, acronitrile
Diene rubbers such as butadiene copolymer rubber (NBR), styrene-butadiene copolymer rubber (SBR),
Examples include acrylic rubbers such as polybutyl acrylate and polypropyl acrylate, and ethylene-propylene-diene rubber (EPDM). These copolymers (A) are produced by conventional solution polymerization or bulk polymerization, and the copolymerized amount of maleic anhydride should be selected within the range of 5 to 50 mol%.
If the copolymerized amount of maleic anhydride is less than 5 mol%, the heat distortion temperature of the resulting maleimide copolymer will be insufficient, and if it exceeds 50 mol%, the heat distortion temperature of the maleimide copolymer will be too high. This is not preferable because it makes melt molding difficult. copolymer
The composition ratio of the vinyl copolymer and the rubbery polymer other than maleic anhydride (A) is not particularly limited and can be arbitrarily selected. The isocyanate ester compound used for imidizing the copolymer (A) in the present invention has the following formula []
It is a compound represented by the formula, and R in the formula has 1 carbon number.
~20 hydrocarbons. R-N=C=O...[] These compounds include methyl isocyanate, ethyl isocyanate, propyl isocyanate, butyl isocyanate, phenyl isocyanate, naphthyl isocyanate, etc., and these are copolymers. It is used in an amount of at least an equivalent, preferably at least 1.02 equivalents, relative to the maleic anhydride contained in (A). The reaction for forming the maleimide copolymer according to the present invention proceeds through the following reaction. That is, a maleimide unit and carbon dioxide are produced from a maleic anhydride unit and an isocyanate ester compound. This reaction forms the maleimide copolymer (B) that is the object of the present invention. It is important that the reaction of the present invention is carried out in a non-aqueous state. This is because, in the presence of water, the isocyanate compound reacts with water to produce primary amines and carbon dioxide. Therefore, it is necessary to pay attention to the moisture content of the isocyanate ester compound and the organic solvent. The reaction of the present invention is generally carried out in a non-aqueous organic solvent, and the organic solvent used here is one that can uniformly disperse the copolymer (A) and does not interfere with the reaction with the isocyanate ester compound. There are no particular limitations, and for example, ketones such as acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone, and amides such as dimethylformamide can be selected. The reaction temperature of the present invention is 0 to 350°C, especially room temperature to
250°C is preferable; below 0°C, the reaction rate is slow;
Moreover, if the temperature exceeds 350°C, thermal decomposition of copolymers (A) and (B) will occur, which is not preferable. The reaction time can be appropriately set depending on the reaction temperature, but from the viewpoint of productivity, it is preferably 5 to 5000 seconds, particularly 30 to 3000 seconds. The reaction pressure is preferably in the range of normal pressure to 5 atm. The apparatus for carrying out the reaction of the present invention is not particularly limited, and any apparatus may be used as long as it has the functions of mixing the reaction system, regulating the temperature, and removing the generated carbon dioxide, such as a normal polymerization tank or a vent. It is also possible to use an extruder with an attached extruder. Thus, according to the present invention, a maleimide-based copolymer having high heat distortion temperature and thermal decomposition temperature and excellent heat resistance can be efficiently obtained using a copolymer containing maleic anhydride as a starting material. Furthermore, the maleimide copolymer obtained in the present invention is
It has excellent miscibility with rubber-modified resins known as ABS resin, AES resin, MBS resin, etc., and can be used as a modifier to impart excellent heat resistance to these resins. That is, diene rubbers such as polybutadiene rubber, acrylonitrile-butadiene copolymer rubber (NBR), styrene-butadiene copolymer rubber (SBR), acrylic rubbers such as polybutyl acrylate and polypropyl acrylate, and ethylene-propylene rubber. The present invention is applied to a rubber modified resin obtained by graft copolymerizing at least one of an aromatic vinyl monomer, a (meth)acrylic acid ester monomer, and a vinyl cyanide monomer to a diene rubber (EPDM), etc. By mixing the maleimide copolymer obtained in the above, it is possible to produce an impact-resistant resin composition that has a high heat distortion temperature, a high thermal decomposition temperature, and a high impact strength. In this case, there is no particular restriction on the mixing ratio of the maleimide copolymer and the above-mentioned rubber-modified resin, and the ratio of the rubber-like polymer and the vinyl monomer to be graft-polymerized in the above-mentioned rubber-modified resin is subject to particular technical restrictions. There are no restrictions. If desired, vinyl copolymers such as styrene-acrylonitrile copolymer and α-methylstyrene-acrylonitrile copolymer, polyamide copolymers such as nylon, polyethylene terephthalate, polybutylene terephthalate, etc. It is also possible to simultaneously mix other polymers such as polyester polymers such as . The mixing method is not limited to any conventional means, and it is also possible to add stabilizers, lubricants, fibrous reinforcing agents, colorants, flame retardants, conductive materials, etc. during mixing. The effects of the present invention will be further explained below with reference to Examples and Comparative Examples. In Examples and Comparative Examples, the heat distortion temperature was measured in accordance with ASTMD-648-56, and the Izod impact value was measured in accordance with ASTMD-256-56Method A. The pyrolysis temperature was determined by increasing the temperature at a rate of 10°C/min under a nitrogen stream using a thermogravimetric analyzer, measuring the change in weight of the sample, and determining the pyrolysis temperature as the temperature at which the sample weight decreased by 3%. . Further, the number of parts represents parts by weight. Example 1 [Production of copolymer (a)] 5 kg of styrene and 2.5 kg of methyl ethyl ketone benzoyl peroxide (initiator) were placed in a polymerization tank with an internal volume of 20 equipped with a reflux condenser, a stirrer, and a dropping funnel.
35g was charged and sufficiently dissolved. Separately, a 40% by weight solution of maleic anhydride in methyl ethyl ketone was prepared and charged into the dropping funnel. Next, a maleic anhydride-methyl ethyl ketone solution was added from the dropping funnel at a rate of 833 g/hr for 3 hours while maintaining the temperature inside the polymerization tank at 75° C. and stirring, and was maintained for 1 hour after the addition was completed. At this time, the polymerization rate had reached 94%. Next, 1240 g of phenyl isocyanate was added to the reaction system, and stirring was continued for 2 hours while maintaining the temperature at 75°C. Next, a large amount of toluene was added to the reaction system to remove methyl ethyl ketone and unreacted monomers, and then dried to obtain 6.8 kg of a pale and colored copolymer (a). When the infrared absorption spectrum of this copolymer (a) was measured, it was the same as that of styrene-N-phenylmaleimide copolymer. Example 2 [Production of copolymer (b)] In the same polymerization tank as in Example 1, 3.8 kg of styrene, 1.2 kg of acrylonitrile, 3.7 kg of methyl ethyl ketone, and 1 kg of polybutadiene rubber with a gel content of 90% were charged and sufficiently dissolved. Meanwhile, 9 g of azobisisobutyronitrile,
A solution of 2 kg of maleic anhydride dissolved in 5 kg of methyl ethyl ketone was charged into the dropping funnel. Next, the polymerization tank was heated to 80 °C, and the above maleic anhydride-methyl ethyl ketone solution was added dropwise at a rate of 875 g/hr.
It was held for 2 hours after the completion of dropping. After that, 30 g of diphenylisodecyl phosphite and 3.5 g of diphenylisodecyl phosphite were added to the reaction solution.
40 g of -di-t-butylhydroxytoluene was added as an antioxidant, and while the temperature inside the polymerization tank was maintained at 80°C, 2500 g of butyl isocyanate was added and stirring was continued for 3 hours. Then, put the reaction solution into the tray.
It was dried in a vacuum oven at 110° C. for 8 hours to remove the solvent and residual monomers, and 3.8 kg of copolymer (b) was obtained. When the infrared absorption spectrum of this copolymer (b) was measured, it was found that styrene-acrylonitrile-N
The infrared absorption spectrum was the same as that of -butylmaleimide-butadiene copolymer. Comparative Example 1 [Production of copolymer (c)] In the same polymerization tank as in Example 1, 5 kg of styrene, 2.5 kg of methyl ethyl ketone, and benzoyl peroxide (initiator) were added.
35g was charged and sufficiently dissolved. Separately, a 40% by weight solution of maleic anhydride in methyl ethyl ketone was prepared and charged into the dropping funnel. Next, while maintaining the temperature inside the polymerization tank at 75℃ and stirring, the maleic anhydride-methyl ethyl ketone solution was added from the dropping funnel.
Added at a rate of 833 g/hr for 3 hours, and after addition
Holds time. Thereafter, when the temperature inside the polymerization tank was cooled to 30°C, a colorless and transparent viscous liquid was obtained, and the polymerization rate was 94%. Next, the reaction solution was added to a large amount of petroleum benzine, methyl ethyl ketone and unreacted monomers were removed, and then dried to obtain a white styrene-maleic anhydride copolymer (c).
5.6Kg was obtained. Example 3 The heat distortion temperature and thermal decomposition temperature of copolymers (a) to (c) obtained in Examples 1 and 2 and Comparative Example 1 were measured, and the results were as shown in Table 1.

[Table] As is clear from Table 1, the copolymer (c) containing maleic anhydride has a low thermal decomposition temperature and insufficient thermal stability. On the other hand, the copolymer produced by the method of the present invention
(a) and (b) have high heat distortion temperatures and high thermal decomposition temperatures, and have extremely excellent heat resistance. Example 4 Copolymers (a) and (b) obtained in Examples 1 and 2 and copolymer (c) obtained in Comparative Example 1, 70 parts and styrene-acrylonitrile with a rubber content of 60% by weight - Blending 30 parts of butadiene copolymer (ABS) or styrene-acrylonitrile copolymer (SAN),
The physical properties of test pieces obtained by melt extrusion and injection molding using an extruder were measured. The measurement results of heat distortion temperature, thermal decomposition temperature and Izod impact strength are shown in Table 2 along with the blending ratio.

[Table] As is clear from the results in Table 2, the composition containing copolymers (a) and (b) obtained by the method of the present invention has a high thermal distortion temperature, thermal decomposition temperature, and Izod impact strength. On the other hand, the composition containing the maleic anhydride-containing copolymer (c) has a low thermal decomposition temperature and insufficient thermal stability.

Claims (1)

[Claims] 1. A vinyl copolymer or a rubber-modified vinyl copolymer containing 5 to 50 mol% of maleic anhydride is added in a non-aqueous organic solvent in an amount equivalent to or more than the maleic anhydride contained in the copolymer. 1. A method for producing a maleimide copolymer, which comprises reacting with an isocyanate ester compound and imidizing the maleimide copolymer.