JPS6210565B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a graft copolymer obtained by graft copolymerizing a polymerizable monomer onto a rubber-like polymer. More particularly, it relates to a dispersant used in a method for polymerizing a polymerizable monomer in an aqueous suspension in the presence of a shredded rubbery polymer. Conventionally, attempts have been made to blend rubber-like polymers into resins with the aim of improving the impact resistance of resins.
In order to improve the impact resistance of a blended composition, a method is known in which a resin-forming monomer is graft-copolymerized to a rubbery polymer in advance. Furthermore, it has been proposed to graft copolymerize various polymerizable monomers onto rubber-like polymers for the purpose of improving properties such as tackiness, adhesion, and oil resistance of rubber. Various methods are known for producing graft copolymers of these rubbery polymers, but
An advantageous method for producing graft copolymers with relatively high rubbery polymer concentrations is the polymerization of polymerizable monomers in aqueous suspension in the presence of shredded rubbery polymers. It has been known. When producing a graft copolymer using this method, the purpose is to prevent rubber particles swollen with polymerizable monomers from agglomerating and forming blocks during polymerization, and to maintain a stable dispersion state. As such, dispersants such as polyvinyl alcohol, alkyl cellulose, and hydroxyalkyl cellulose are used.
However, when producing a graft copolymer using this method, in addition to the desired graft copolymer, the polymerizable monomer is not impregnated into the shredded rubber particles and polymerizes alone outside the rubber particles. There was a problem in that a large amount of polymerized products (hereinafter referred to as by-product polymerized products) were simultaneously produced. The production of this large amount of by-product polymers not only causes a decrease in the monomer unit consumption, but also removes the by-product polymers, which adhere to the reaction vessel or the stirring blades of the reactor. The drawback was that it required a lot of effort and time. In addition, the graft copolymer produced has a low grafting rate, and furthermore, the graft copolymer contains
Since it contains a large amount of rubbery polymer that is not graft-bonded, it was not always possible to obtain satisfactory physical properties. As a result of intensive research in order to improve these drawbacks, the present inventors found that in a method of graft copolymerizing a polymerizable monomer in an aqueous suspension in the presence of a shredded rubbery polymer, the general formula HO (C ₂ H ₄ O) _a (C ₃ H ₆ O) _b (C ₂ H ₄ O) _c H (where a, b, and c each represent a number from 10 to 1000) By using an ether compound as a dispersant, by-product polymers can be
It has been discovered that it is possible to produce a graft copolymer of extremely excellent quality in which almost no copolymer is produced, the graft ratio is high, and the amount of ungrafted rubbery polymer is significantly reduced, and the present invention has been achieved. Rubbery polymers used in the present invention include ethylene-α-monoolefin copolymer, ethylene-α-monoolefin-nonconjugated diene terpolymer, styrene-butadiene copolymer, polybutadiene, and polyisoprene. , natural rubber, acrylonitrile-butadiene copolymer, ethylene-vinyl acetate copolymer, acrylic rubber, etc. Examples of the polymerizable monomer used in the present invention include aromatic compounds such as styrene, halogenated styrene, α-methylstyrene, and P-methylstyrene, unsaturated nitrites such as acrylonitrile and methacrylonitrile, acrylic acid, and methacryl It is one type or a mixture of two or more of vinyl fatty acids such as acids, acrylic acids such as methyl acrylate and methyl methacrylate, alkyl esters of methacrylic acid, and vinyl chloride. In the present invention, the ratio of the rubbery polymer to the polymerizable monomer varies depending on the type of monomer or the desired properties of the graft copolymer to be produced, but in general, it is based on 100 parts by weight of the rubbery polymer. Monomer 1~
It is 900 parts by weight. The monomer may be added in its entirety before the start of polymerization, or a part of it may be added before the start of polymerization,
The remainder may be added continuously or batchwise as the polymerization progresses. In the present invention, the amount of water used is not particularly limited as long as the rubber particles remain in a stable aqueous suspension, but generally the total weight of the rubbery polymer and polymerizable monomer is 100%. 50 to 1000 parts by weight per part is appropriate. In the present invention, the amount of the block type polyether compound used as a dispersant is not particularly limited, but if it is too small, it will be impossible to maintain a stable suspension state, and the resulting graft copolymer will be If the amount is too large, foaming during polymerization will be severe, which is not preferable. A suitable amount is 0.01 to 1 part by weight per 100 parts by weight of water. In the present invention, known monomer-soluble polymerization catalysts are used for graft polymerization. For example, organic peroxides such as benzoyl peroxide, lauroyl peroxide, t-butyl peroxypivalate, t-butyl hydroperoxide, dicumyl peroxide, azobisisobutyronitrile,
Azo compounds such as azobisdimethylvaleronitrile are used. The polymerization catalyst may be added dissolved in the monomer, or may be added alone.
Further, the entire amount of the polymerization catalyst may be added before the start of the polymerization, or it is also possible to add a part of the catalyst before the start of the polymerization and add the rest in portions during the polymerization. Furthermore, when carrying out the method of the present invention, it is also possible to add known oxidation stabilizers, ultraviolet absorbers, etc. as necessary.Furthermore, depending on the use of the graft copolymer, lubricants, Additives such as plasticizers can be used. According to the present invention, there is almost no formation of by-product polymers when producing a graft copolymer, almost no polymer is observed to adhere to the reaction vessel after the reaction is completed, and the yield of the graft copolymer is also reduced. It is characterized by an increase in In addition, in order to obtain a uniform graft copolymer,
It is necessary to uniformly impregnate the shredded rubbery polymer with a polymerizable monomer, and for this purpose conventionally the monomer is added to rubber particles suspended in water and then polymerized. A long impregnation time was required before the reaction started, but according to the method of the present invention, rubber particles are impregnated with a monomer extremely quickly, and almost no impregnation time is required. These things make it possible to improve the raw material consumption rate, reduce the amount of labor and time required to remove by-product polymers attached to the reaction vessel, and improve productivity by shortening the impregnation time. Its industrial value is extremely large. Furthermore, the graft copolymer obtained by the method of the present invention has a high grafting rate and is further characterized in that the amount of non-grafted rubber components in the product is significantly reduced. Therefore, when the graft copolymer obtained by the method of the present invention is blended with other resins as an impact modifier, the compatibility between the resin component and the rubber component is improved, and the resulting composition is improved. It has extremely excellent impact resistance. The reason why these effects are obtained by using a specific dispersant is not clear, but it is presumed to be as follows. When monomers are added to an aqueous suspension, some of the monomers are not impregnated into the shredded rubbery polymer but are emulsified by the dispersant and left outside of the rubber particles. When a by-product polymer is generated by suspension polymerization of this residual monomer alone, when a block type polyether compound is used as a dispersant, the emulsifying effect of the monomer is It is thought that the above effect is obtained because the impregnation rate of the monomer into the rubber particles is weak and the rate of impregnation of the monomer into the rubber particles is fast, and suspension polymerization of residual monomers that are not impregnated into the rubber particles is difficult to occur. Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples or the above reasoning. Example 1 In a 5 autoclave equipped with a stirrer, 1.5 g of Pluronic F68 (average molecular weight 8350, polyethylene glycol content 80%) manufactured by Asahi Denka Co., Ltd. as a block type polyether dispersant was dissolved in 1950 pure water.
ml, and 300 g of ethylene-propylene-ethylidene norbornene ternary copolymer rubber (iodine value 21.1, Mooney viscosity at 100°C 76, propylene content 46.0% by weight) shredded into 4 to 6 meshes and stirred to suspend. Ta. Next, as a polymerization initiator, t-
Butyl peroxypivalate 9g and p-quinone
A monomer mixture of 120 g of acrylonitrile containing 0.15 g and 225 g of styrene is added, and immediately steam is blown into the autoclave jacket to start raising the temperature. After 20 minutes, the temperature reached 100°C, and the temperature was kept at 100°C for 1 hour to carry out the polymerization reaction. There was no by-product polymer in the suspension after the completion of the reaction, and there was also no by-product polymer adhering to the reaction vessel and the stirring blade. The resulting granular graft copolymer was washed with water and then vacuum-dried at 80°C. The yield of graft copolymer was 593 g. 3 g of the product was immersed in a mixed solution of 50 ml of tetrahydrofuran and 110 ml of acetone for 24 hours to extract the non-grafted acrylonitrile-styrene copolymer in the graft copolymer. The extraction amount was 13.4%. Here, if the graft ratio is defined as the amount of graft-bonded acrylonitrile-styrene copolymer divided by the amount of rubber component in the graft copolymer, the value is 71%. Then, 3 g of the product was boiled in n-hexane under reflux.
It was immersed in 300 ml for 40 hours to extract non-grafted rubber components in the graft copolymer.
The extraction amount was 10.6%. Here, if the amount of ungrafted rubber is defined as the amount of rubber not graft bonded/the amount of rubber component of the graft copolymer, the value is 21%. Furthermore, in order to examine the performance of the product as an impact resistance imparting agent for resins, it was blended with an acrylonitrile-styrene copolymer resin (manufactured by Daicel Corporation, Sevian No. 50 hereinafter referred to as AS resin). The blending ratio was adjusted so that the amount of rubber component in the final blended composition was 26% by weight. The notched Izot impact strength of the blended composition is 83
It was Kg・cm/ ^cm2 . Comparative Example 1 Polyvinyl alcohol as a dispersant (polymerization degree
2400, saponification degree 89%), and after adding the monomer, continue stirring at 40℃ for 1 hour to impregnate the rubber particles with the monomer, and then raise the temperature to 100℃ to initiate the polymerization reaction. A graft copolymer was produced in the same manner as in Example 1, except that A large amount of fine by-product polymers precipitates or floats in the suspension after the reaction, and the by-product polymers form a layer of about 1 mm in the reaction vessel and stirring blade. It was attached. The total yield of these by-product polymers was 76 g,
The yield of graft copolymer was 508 g. The grafting rate of the graft copolymer is 37%, the amount of ungrafted rubber is 49%, and the notched isot impact strength of the blended composition with AS resin is 55Kg・cm/cm ²
It was hot. Comparative Examples 2 to 5 Hydroxypropyl methyl cellulose as a dispersant (19 to 24% methoxy groups, 4 to 12% hydroxypropoxy groups, viscosity of 2% aqueous solution at 20°C)
100cp), and the impregnation time at 40℃ from the time of monomer addition until the start of temperature rise was 0, 1, 3,
A graft copolymer was produced in exactly the same manner as in Example 1, except that the heating time was 6 hours.

[Table] Examples 2 and 3 Pluronic F-88 (average molecular weight 11500, polyethylene glycol content 80%) and Pluronic L-44 as block type polyether dispersants
(Average molecular weight 2750, polyethylene glycol content 40
A graft copolymer was produced in the same manner as in Example 1 except that %) was used. On this day, a small amount of by-product polymer floating in the suspension water was produced, but almost no adhesion to the reaction vessel etc. was observed.

[Table] Example 4 As a rubber component, ethylene-propylene-dicyclopentadiene terpolymer (iodine value 16.3,
A graft copolymer was produced in the same manner as in Example 1, except that a polymer having a Mooney viscosity of 87 at 100°C and a propylene content of 29% by weight was used. Comparative Example 6 A graft copolymer was produced in the same manner as in Example 4, except that hydroxypropyl methylcellulose was used as a dispersant and the impregnation time at 40°C after monomer addition was 1 hour. .

【table】

Claims (1)

[Claims] 1. A method of graft copolymerizing a polymerizable monomer to a shredded rubbery polymer in an aqueous suspension,
As a dispersant, the general formula HO (C ₂ H ₄ O) _a (C ₃ H ₆ O) _b (C ₂ H ₄ O) _c H (where a, b, and c each represent a number from 10 to 1000) 1. A method for producing a graft copolymer, which comprises using a block polyether compound represented by: 2. The method according to claim 1, wherein the rubbery polymer is an ethylene-α-monoolefin copolymer rubber or an ethylene-α-monoolefin-nonconjugated diene terpolymer rubber. 3. The method according to claim 1, wherein the polymerizable monomer is a mixed monomer of acrylonitrile and styrene.