JP3189155B2 - Method for producing graft copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a graft polymer having excellent heat resistance, rigidity and impact resistance.

[0002]

2. Description of the Related Art Various studies have been conducted on maleimide copolymers because of their high heat resistance. For example, a method of copolymerizing N-aromatic substituted maleimide with methyl methacrylate is disclosed in JP-B-43-9753, JP-A-61-14.
JP-A-17-6891, JP-A-61-171708 and JP-A-62-109811 disclose a method of copolymerizing an N-aromatic substituted maleimide with a styrene resin. It is disclosed in JP-A-61-76512 and JP-A-61-276807.

[0003] However, the resin obtained by this method is N-
As the content of the aromatic-substituted maleimide increases, the heat resistance becomes better, but there are problems such as very brittleness, poor processability, and coloring, and a small amount as a heat resistance improver for acrylonitrile / butadiene / styrene (ABS) resin. It is merely used to be added.

On the other hand, N-alkyl-substituted maleimide-olefin copolymers are interesting polymers having properties such as excellent heat resistance, high rigidity and practical mechanical strength, but further improvement in impact strength is desired. It is rare.

Japanese Patent Publication No. 49-12576 discloses a resin composition of a maleimide copolymer and rubber, but has little effect on improving bending strength and impact strength.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a graft copolymer having excellent heat resistance, rigidity and impact resistance.

[0007]

Means for Solving the Problems The present inventors have made intensive studies in view of this problem, and as a result, have found that the above object can be achieved by polymerizing an N-alkyl-substituted maleimide compound and an olefin with a radical initiator in the presence of a rubber compound. The present inventors have found that a graft copolymer satisfying the above condition can be produced, and have completed the present invention.

That is, the present invention is characterized in that a monomer mixture comprising a maleimide compound (I) and an olefin (II) shown below is copolymerized with a radical initiator in the presence of a diene rubber compound. And a method for producing a graft copolymer.

[0009]

Embedded image (Where R ₁ represents an alkyl group having 1 to 18 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms)

[0010]

Embedded image (Here, R ₂ , R ₃ and R ₄ each represent hydrogen or an alkyl group having 1 to 8 carbon atoms.) Examples of the maleimide compound include N-methylmaleimide, N-ethylmaleimide, and Nn-propylmaleimide. , Ni-propylmaleimide, Nn-butylmaleimide, Ni-butylmaleimide, Ns-butylmaleimide, Nt-butylmaleimide, Nn-pentylmaleimide, Nn-
Hexylmaleimide, Nn-heptylmaleimide, N
-N-octylmaleimide, N-laurylmaleimide,
N-alkyl-substituted maleimides such as N-stearylmaleimide, N-cyclopropylmaleimide, N-cyclobutylmaleimide, N-cyclohexylmaleimide, and the like. Are preferably maleimides having a cycloalkyl group of 3 to 6, especially N-methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide and N-
Cyclohexylmaleimide is preferred. These can be used alone or in combination of two or more.

The olefins include ethylene, isobutene, 2-methyl-1-butene, 2-methyl-1-
Pentene, 2-methyl-1-hexene, 1-methyl-1
-Heptene, 1-isooctene, 2-methyl-1-octene, 2-ethyl-1-pentene, 2-methyl-2-butene, 2-methyl-2-pentene, 2-methyl-2-hexene and the like. From the viewpoint of heat resistance and mechanical properties, 1,1-disubstituted olefins, particularly isobutene, are preferred. These can be used alone or in combination of two or more.

Further, if necessary, other vinyl monomers can be copolymerized as long as the object of the present invention is not impaired. Other vinyl monomers include styrene, α-methylstyrene, vinyltoluene, 1,3-
Butadiene, isoprene and their halogen-substituted derivatives, methacrylates such as methacrylic acid, methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, hydroxyethyl methacrylate, methyl acrylate, acrylic acid Acrylic esters such as ethyl, butyl acrylate, cyclohexyl acrylate, phenyl acrylate and benzyl acrylate; vinyl esters such as vinyl acetate and vinyl benzoate; methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether;
One or more compounds selected from monomers such as vinyl ethers such as butyl vinyl ether, vinyl chloride, vinylidene chloride, N-phenylmaleimide, and acrylonitrile.

The rubbery compound used in the production method of the present invention means an elastic or viscous substance having a glass transition temperature of 10 ° C. or lower, preferably 0 ° C. or lower, more preferably -20 ° C. or lower.

These rubbery compounds include diene rubbers such as polybutadiene, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl methacrylate / butadiene copolymer, polyisoprene, polychloroprene, and hydrogenated products thereof. , Polyethylene, ethylene / propylene / ethylidene norbornene copolymer,
Olefinic elastomers such as butyl rubber, ethylene / vinyl acetate copolymer, ethylene / methyl acrylate copolymer, and acrylic acid such as ethyl acrylate / butyl acrylate copolymer, ethyl acrylate / allyl acrylate copolymer Ethyl-based acrylic rubber, silicones, fluorine-based rubber, urethane-based rubber, ester-based rubber,
Amide rubbers and the like can be mentioned.

The molecular weight of these rubbery compounds is not particularly limited, but the molecular weight is more than 1000, especially 1000
It is preferably 0 or more, and these rubber compounds may be cross-linked, or the characteristics may be improved by forming a structure such as a core-shell.

Further, it is preferable that these rubber compounds have a double bond, a halogen group, a thiol group, and the like for producing a graft polymer.

By selecting a rubber-like compound, the obtained graft polymer can have properties such as low-temperature impact resistance, oil resistance, moldability, and weather resistance. Among them, diene-based elastomers have excellent low-temperature impact resistance and olefins. Elastomers and acrylic elastomers are preferred examples having particularly excellent weather resistance and impact resistance.

The proportion of the maleimide compound, olefins and rubber compound used in the method for producing the graft copolymer of the present invention is not particularly limited. For example, in the presence of 100 parts by weight of the rubber compound, the maleimide compound 25 to
The heat resistance, bending strength and impact are obtained by charging a maleimide compound and an olefin so that the ratio of the olefin / maleimide compound is at least 0.02 (molar ratio) and 1900 parts by weight, and copolymerizing with a radical polymerization initiator. The trunk having excellent strength is a rubber compound, the branch is a maleimide / olefin copolymer, and the ratio of the trunk to the branch is 5 to 80/95 to
20% by weight of the graft copolymer are obtained.

In this case, the amount of the maleimide compound used is 100 to 1900 parts by weight, and 150 to 9 parts by weight.
When the content is 00 parts by weight, the above-mentioned physical properties of the obtained graft copolymer are further improved, so that it is preferable.

Further, maleimide /
The composition ratio of maleimide units / olefin units in the olefin copolymer is preferably 30 to 98/70 to 2 mol%, more preferably 40 to 85/60 to 15 mol%, and particularly preferably 50 to 80/50 to 50 mol%. 20 mol% is preferred.
When the amount of the maleimide unit is more than 98 mol%, the mechanical strength of the resulting graft copolymer may be reduced.
If it is less than 0 mol%, the heat resistance of the graft copolymer tends to decrease.

The graft ratio of the copolymer can be determined by solvent extraction or the like. According to the production method of the present invention, (the charged rubber amount−the unreacted rubber amount) / the charged rubber amount × 10
The graft ratio indicated by 0 is 5% or more, preferably 50%.
% Or more, particularly preferably 80% or more, and an unreacted rubber component may be present. Further, a maleimide / olefin copolymer may be added to the obtained graft copolymer.

The obtained graft copolymer has a shear rate of 10 ³ s at a temperature of heat distortion temperature + (100 to 200 ° C.).
Those having a melt viscosity at ec ^-1 of 10 to 1,000,000 poise, particularly 100 to 100,000 poise are preferred.

For the polymerization of these graft copolymers, any of known polymerization methods such as bulk polymerization, bulk-suspension polymerization, solution polymerization, suspension polymerization and emulsion polymerization can be employed.

The reactor used for the polymerization is not particularly limited, but known devices such as various autoclaves and melt kneaders can be used alone or in combination. There is no particular limitation on the material of the reactor, glass, stainless steel,
Titanium, Hastelloy or the like is used.

Examples of the polymerization initiator include benzoyl peroxide, lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-tert-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, and t-butyl peroxyacetate.
Or an organic peroxide such as t-butylperoxybenzoate, or 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-butyronitrile), 2,2 ′ -Azobisisobutyronitrile, dimethyl-2,2'-azobisisobutyrate, 1,1'-
An azo initiator such as azobis (cyclohexane-1-carbonitrile) is exemplified.

Solvents usable in the solution polymerization method include benzene, toluene, xylene, ethylbenzene,
Cyclohexane, dioxane, tetrahydrofuran, acetone, methyl ethyl ketone, dimethylformamide,
Isopropyl alcohol, butyl alcohol and the like can be mentioned.

The emulsion polymerization can be carried out, for example, by introducing a maleimide compound, an olefin, an initiator and the like in the presence of a rubbery latex.

The polymerization temperature can be appropriately set in accordance with the decomposition temperature of the initiator, but is generally preferably in the range of 40 to 300 ° C.

In the resin obtained in the present invention, if necessary, polyethylene, polypropylene, polyvinyl chloride, polystyrene, styrene / acrylonitrile copolymer, styrene / maleic anhydride copolymer, acrylic resin, imidized acrylic Resin, polyamide, polyester, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyethersulfone, polyamideimide,
Polyimide, silicone resin, fluorine resin, phenol resin, epoxy resin, diene rubber, olefin rubber,
Homopolymer such as acrylic rubber, random, block,
A graft copolymer and a mixture or a modified product thereof can also be mixed.

Further, various dyes, glass fibers, carbon fibers,
Potassium titanate, asbestos, silicon carbide, ceramic fiber, metal fiber, silicon nitride, barium sulfate, calcium sulfate, kaolin, clay, pyroferrite, zeolite, mica, mica, talc, ferrite, calcium silicate, calcium carbonate, magnesium carbonate Heat stabilizers such as inorganic and organic fillers such as antimony trioxide, zinc oxide, titanium oxide, iron oxide, glass balloon, and aramid fiber, hindered phenol, and organic phosphoric acid ester; benzotriazole; An ultraviolet stabilizer such as a hindered amine type, a flame retardant, a flame retardant auxiliary, a foaming agent, an antistatic agent, various lubricants and the like may be added. These additives can be used in various combinations.

The resin obtained in the present invention can be formed into various molded articles, sheets, films, fibers, and the like by known injection molding, extrusion molding, blow molding, foam molding, vacuum molding, and the like. it can. Further, the obtained molded body can be subjected to a treatment such as plating, painting, printing and the like.

[0032]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the examples.

The produced polymer was confirmed by IR measurement and elemental analysis. The molecular weight of the obtained polymer was
Meation chromatography (HLC-8 manufactured by Tosoh Corporation)
02A) in terms of polystyrene.

The obtained sample was heated at 240 to 320 ° C. using a twin screw extruder (Laboplast Mill (manufactured by Toyo Seiki)).
Into pellets, and pelletize the obtained pellets using an injection molding machine (Panajection (Matsushita Electric Industrial Co., Ltd.)).
Injection molding was performed at a temperature of 240 to 350 ° C and a mold temperature of 60 to 120 ° C to obtain a sample for measuring physical properties.

The heat distortion temperature of the obtained sample is ASTM
D648 (18.5 kg / cm ² load), flexural strength and flexural modulus were measured according to ASTM D790, and notched impact strength was measured according to ASTM D256.

Example 1 208 g of polybutadiene (BR01; manufactured by Nippon Synthetic Rubber) and toluene 1 were placed in a 30-liter autoclave equipped with a stirrer, a nitrogen inlet tube, an isobutene inlet tube, a thermometer and a degassing tube.
After charging 0 l and dissolving polybutadiene, 5 l of a toluene solution of 785 g of N-methylmaleimide and 25 g of benzyl peroxide (BPO) were charged and purged several times with nitrogen, and then 5.7 l of liquefied isobutene.
And polymerized at 70 ° C. for 10 hours.

The reaction content was poured into an excess of methanol to precipitate a polymer, and the polymer was separated by centrifugation.
It dried at 60 degreeC under reduced pressure for 24 hours. The yield was 1350 g.

A part of the obtained polymer was taken out and subjected to Soxhlet extraction using toluene as a solvent. The extraction residue was 98%, and IR analysis of the extraction residue confirmed characteristic absorption derived from polybutadiene and characteristic absorption derived from imide groups, and confirmed that a graft copolymer was formed.

The obtained sample was pelletized using a twin screw extruder, and a test piece was prepared by injection molding. Table 1 shows the characteristic evaluation results.

REFERENCE EXAMPLE 1 N-methylmaleimide 118 was added to the reactor described in Example 1.
After charging 0 g, 8.5 g of perbutyl neodecaneate and 15 l of a mixed solvent of toluene / methanol (1/1 by volume) and purging with nitrogen several times, the ratio of N-methylmaleimide to isobutene was determined. Liquefied isobutene was charged in the same manner as in 1, and polymerization was carried out at 60 ° C. for 10 hours.

After polymerization, the polymer was obtained as a particulate solid. The polymer particles and the solvent were separated by centrifugation. It dried at 60 degreeC under reduced pressure for 24 hours. The average particle size of the obtained polymer particles was 350 μm, and the yield was 1800 g.

The weight average molecular weight of the obtained polymer was 24.
From the results of elemental analysis of the sample purified by reprecipitation, the number of maleimide units in the produced polymer was 50.
Mol%.

Since the polymerization was carried out at the same monomer charge ratio as in Example 1, it can be assumed that the ratio of N-methylmaleimide to isobutene in the polymer obtained in Example 1 is also the same. Several batch polymerizations were performed under the same conditions to prepare samples.

Example 2 Using the same reactor as in Example 1, polybutadiene 29
4 g and 785 g of N-methylmaleimide in toluene 1
Dissolved in 5 l, charged with 25 g of BPO, purged several times with nitrogen, charged with 5.7 l of liquefied isobutene,
For 12 hours.

The reaction content was poured into ethanol and the polymer
Was precipitated. After centrifugation, it was dried at 60 ° C. under reduced pressure for 24 hours. The yield was 1400 g. The characteristics were evaluated in the same manner as in Example 1. Table 1 shows the obtained results.

Example 3 Using the same reactor as in Example 1, polybutadiene 29
4 g and 392 g of N-methylmaleimide in toluene 1
Dissolved in 5 l, charged with 12.5 g of BPO, purged several times with nitrogen, and charged with 2.9 l of liquefied isobutene.
The reaction was performed at 0 ° C. for 12 hours.

The reaction content was poured into ethanol and the polymer
Was precipitated. After centrifugation, it was dried at 60 ° C. under reduced pressure for 24 hours. The yield was 880 g.

To the obtained sample, 590 g of the N-methylmaleimide / isobutene copolymer prepared in Reference Example 1 was added.
In addition, pellets were formed using a twin screw extruder, and test pieces were prepared by injection molding. Table 1 shows the results of the characteristic evaluation.

Comparative Example 1 850 g of the sample prepared in Reference Example 1 was uniformly dispersed in a toluene solution of 150 g of polybutadiene, and the polymer was precipitated with an excess of methanol.
After separation and drying, pelletization and injection molding were performed in the same manner, and the characteristics were evaluated. Table 1 shows the obtained results.

Comparative Example 2 Similarly to Comparative Example 1, the sample 800 obtained in Reference Example 1 was obtained.
g and a sample composed of 200 g of polybutadiene were prepared and evaluated for characteristics. Table 1 shows the obtained results.

Comparative Example 3 800 g of pellets obtained by extruding the sample obtained in Reference Example 1 using a twin-screw kneader and 200 g of ethylene propylene rubber pellets (EPR941P manufactured by Nippon Synthetic Rubber) were similarly subjected to a twin-screw kneading extruder. Pellets were formed and test pieces were prepared by injection molding. Table 1 shows the results of the characteristic evaluation.

[0052]

[Table 1]

[0053]

As is clear from the examples, the samples obtained by the production method of the present invention have excellent properties such as excellent heat resistance, impact resistance, and rigidity, and are therefore excellent in automobiles, It is extremely useful in a wide range of applications such as electrical and electronic, precision machinery, housing, food, and medical fields.

Claims (1)

(57) [Claims] 1. A diene-based monomer mixture comprising a maleimide compound (I) and an olefin (II) shown below:
A method for producing a graft copolymer, comprising copolymerizing with a radical initiator in the presence of a rubber compound of the formula (1). Embedded image (Where R ₁ represents an alkyl group having 1 to 18 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms) (Where R ₂ , R ₃ and R ₄ each represent hydrogen or an alkyl group having 1 to 8 carbon atoms)