KR0181523B1 - Process for preparation of nitryl copolymers having good polymeric stabilities - Google Patents

Abstract

The present invention relates to a method for producing a copolymer composed of an unsaturated nitrile compound and an aromatic vinyl compound.

An object of the present invention is to produce a copolymer having a high content of unsaturated nitrile compound and a uniform particle size and composition.

The present invention is used to prepare a nitrile copolymer having an unsaturated nitrile compound monomer content in the range of 33 to 80% by weight and an aromatic vinyl monomer in the range of 20 to 67% by weight by hydropolymerization. 0.005-2.5 parts by weight of an inorganic suspending agent, 0.0005-.01 parts by weight of a carboxyxin anionic surfactant, and 0.0005-0.05 parts by weight of a phosphorus ester dispersant based on 100 parts by weight of the monomer compound It is characterized by using in combination with the range.

Description

[Name of invention]

Process for producing nitrile copolymer having excellent polymerization stability

Detailed description of the invention

The present invention relates to a method for preparing a copolymer composed of an unsaturated nitrile compound and an aromatic vinyl compound. Particularly, a copolymer having a high content of unsaturated nitrile in an underwater suspension polymerization is uniform in composition and particle size distribution due to good polymerization stability. It relates to a method for producing good chemical resistance, gas barrier properties and color tone.

Copolymers containing unsaturated nitrile compound components, in particular styrene-acrylonitrile copolymers, are widely used commercially due to their excellent transparency, thermal stability and mechanical properties. Among these copolymers, styrene-acrylonitrile copolymers containing a high proportion of acrylonitrile have extremely excellent properties in gas barrier properties and chemical resistance, in addition to the above characteristics. It is used for matrix resin of commercial materials.

Commercially used suspension, emulsification, solution, and bulk polymerization can be used for the preparation of these copolymers. However, suspension polymerization, which is inexpensive in manufacturing cost and easy to control and separate, is generally used.

In this polymerization, the ratio of monomers necessary to prepare a copolymer having a desired nitrile content until the end of the reaction, considering that the ratio of the nitrile component is high and the reactivity of the aromatic vinyl monomer and the unsaturated nitrile monomer is different in order to uniformly polymerize the composition. Action should be taken to keep it constant.

To this end, in general, a method of supplying a part of the monomer having a high reactivity is continuously or intermittently supplied into the reaction system in proportion to the reaction rate. When such a method is applied to the suspension polymerization method for preparing the copolymer, when the inorganic dispersing agent, organic polymer dispersing agent, or surfactants, which are generally used alone, are used alone, the air is deteriorated during the polymerization reaction. The problem is that the distribution of particles in the coalescence is uneven, that very large particles or agglomerations are generated, and that the composition of the copolymer is also uneven, resulting in poor transparency, color tone, and physical properties.

In addition, even in the case of using a specific suspension aid combination to improve the suspension performance of the inorganic suspending agent, as in Japanese Patent Publication No. 53-126094, the increase in the unsaturated nitrile compound component in the monomer component and the continuous supply during the polymerization reaction. Due to the monomers, the suspension state is greatly worsened after the reaction, which results in the same results as when the suspension is used alone.

Therefore, a copolymer having an unsaturated nitrile compound component of the final copolymer having a content of 30% by weight or more is polymerized by in-water suspension to prepare a copolymer having excellent transparency and color tone due to uniform particle size distribution and uniform composition. In spite of the increase in the amount of unsaturated nitrile monomers dissolved in the mixture and the further supply of monomers to the reaction system during the reaction, the suspension can form a stronger protective layer so that the suspension can be stably maintained until the end of the polymerization reaction. A combination of agents is necessary.

The present inventors have studied to solve the above problems, and as a result, in order to prepare a copolymer having a high content of unsaturated nitrile compound and uniform particle size and composition by water suspension polymerization, the inorganic suspending agent and the inorganic suspending agent act on the surface of the inorganic When anionic surfactants of carboxylic acid which increase the dispersibility of the suspension in water and phosphate esters dispersants which increase the adsorption power between the inorganic and dispersed monomer droplets are used in a combination of specific contents It turned out that it was possible.

Detailed description of the invention

1. Copolymerization Components

The high nitrile copolymer produced in the present invention has a content of 33-80% by weight of the unsaturated nitrile monomer component in the resulting copolymer and a content of 20-67% by weight of the aromatic vinyl monomer component. Preferably, the content of the unsaturated nitrile monomer component is in the range of 35 to 70% by weight and the content of the aromatic vinyl monomer component is in the range of 30 to 65% by weight.

If the content of the unsaturated nitrile monomer component is less than 33% by weight, the gas barrier property and chemical resistance of the copolymer are insufficient, and if the content of the unsaturated nitrile monomer component is more than 80% by weight, the moldability of the copolymer and the thermal stability during molding processing This is significantly worse and not practical.

The unsaturated nitrile monomer in the raw material monomer of the copolymer of the present invention may be one of acrylonitrile and methacrylonitrile or a mixture thereof, and as the aromatic vinyl monomer, styrene, α-methylstyrene, p-methystyrene, It is preferable that it is one of t-butylstyrene, styrene halide, or a mixture thereof.

In addition to the raw monomers described above, some of the aromatic vinyl monomer components (up to 10% by weight, usually up to 5% by weight) may be replaced with a small amount of one or more ethylenically unsaturated monomers in order to modify the properties of the copolymer. Examples of these are monomers such as acrylic acid esters, methacrylic acid esters, maleimides, and N-phenylmaleimide. In addition, rubber components such as polybutadiene, acrylonitrile-butadiene copolymer, butyl polyacrylate, and antioxidants such as di-t-butyl paracresol, and porous modifiers such as butyl stearate may be used before or after the copolymerization reaction. Can be added to.

2. Polymerization initiator

Examples of the initiator used in the present invention include peroxides such as lauryl peroxide, di-t-butyl peroxide, 2,2'-azobisisobutyronitrile, 1-t-butylazo-1-cyanocyclohexane, and the like. Azo compounds of are preferred. The polymerization initiator can be added to the reaction system all at once or continuously.

The amount and method of addition vary depending on the polymerization conditions such as the continuous supply time of the aromatic vinyl compound in the polymerization step, the polymerization start temperature and the composition ratio of the monomers.

The polymerization initiator used in the present invention is generally in the range of 0.01 to 0.8 parts by weight based on 100 parts by weight of the total used monomers, and preferably in the range of 0.05 to 0.5 parts by weight.

3. Suspension

As the inorganic suspending agent used in the present invention, various compounds such as tricalcium phosphate, calcium hydroxy apatite, barium sulfate, talc, bentonite, and the like, which are generally known, may be used. Phosphates that are insoluble in water, such as tricalcium phosphate and calcium hydroxy apatite, which can be easily dissolved and removed from the back, are particularly preferred.

The amount of these inorganic suspending agents varies depending on the type of monomer, the continuous supply time of the aromatic vinyl compound, the composition ratio of the monomer, the ratio of the total monomers to water, the polymerization conditions, and the like. About 2.5 parts by weight is preferred. This amount should also increase as the ratio of unsaturated nitrile monomers in the total monomers increases, and as the ratio of water to total monomers increases.

The inorganic suspending agent is characterized by an increase in the amount of unsaturated nitrile monomers dissolved in water due to an increase in the proportion of unsaturated nitrile compound components in the reaction mixture and due to the aromatic vinyl monomers which are continuously supplied to the reaction system to prepare a copolymer of uniform composition. Above the conversion rate, the suspension begins to deteriorate rapidly.

As a result, the final polymer may have an extremely wide particle size distribution and a large amount of fairly large particles, or in severe cases, all or a part of the reaction mixture may agglomerate and stick to the reactor wall and the stirring rod. In addition, the composition of the resulting copolymer becomes nonuniform, resulting in poor hue, transparency, and physical properties. In order to prevent such a decrease in suspension efficiency, the following two compounds are used.

First, it is a carboxylic acid-based anionic surfactant, which acts on the surface of the inorganic suspending agent to increase the protection of the dispersant, increase the dispersibility of the inorganic suspending agent in water, and reduce the content of unsaturated nitrile monomer dissolved in water. Do it.

The amount of this compound is also dependent on the polymerization conditions and should be increased when the ratio of water to total monomers and the proportion of unsaturated nitrile components in the monomer components increases, but the appropriate amount should be 0.0005-0.1 for 100 parts by weight of the total monomers used. It is about a weight part. If the amount is less than 0.0005 parts by weight, the effect on the inorganic suspending agent is weak, and the effect is small. If the amount is more than 0.1 parts by weight, the particle size distribution of the produced copolymer is widened, resulting in the production of large and extremely fine particles larger than the desired particle size. It is undesirably lowered and the loss rate in the post-treatment process is increased.

The second is a Phosphate Esters-based dispersant which increases the adsorption between the inorganic dispersant and the dispersed monomer droplets, and introduces and diffuses some of the monomers dissolved in water and the monomers continuously supplied to the reaction system into the suspended droplets. It helps to become a person. Such compounds include polyoxyethylene alkyl ether phosphate esters, polyoxyethylene alkyl aryl ether phosphate esters, and the like, and those of HLB 6-16 are mainly used.

The amount of the compound used also depends on the polymerization conditions, but is more influenced by the amount of monomer dissolved in water and the unit hourly supply and the feed time of the monomer continuously supplied to the reaction system, rather than the ratio of water to the total monomers used. . A proper amount of this compound is 0.0005-0.5 parts by weight based on 100 parts by weight of the total monomers used. If it is less than 0.0005 parts by weight, the action at the interface between the inorganic dispersant and the droplets is weak, and if it is used in excess of 0.05 parts by weight, it is not good because it causes undesirable adverse reactions and makes the particle size distribution of the resulting copolymer uneven.

Combinations and suitable combinations of the above inorganic suspensions, carboxylic acid anionic surfactants and phosphate ester compounds solve the problems arising from the suspension state instability during polymerization described above, resulting in a uniform particle size and composition of the resulting polymer, The color, transparency, physical properties, etc. are excellent characteristics.

3. Copolymerization Process

In the present invention, the polymerization method of the nitrile-based resin copolymer is not significantly different from the ordinary water suspension polymerization except for the combination and the content of the suspending agent. However, since the reactivity of the unsaturated nitrile monomer and the aromatic vinyl monomer is different from each other, the composition of the monomer in the reaction system is changed as the higher reactivity monomer is consumed faster and the reaction proceeds, so that the composition of the monomer is different. It needs to be kept constant.

As is well known, the composition of the produced copolymer depends on the monomer composition ratio and monomer reactivity ratio in the reaction system, and when the copolymerization reaction is carried out in the reaction system of a certain monomer composition ratio, the composition ratio of the monomer is azotrope composition. Except for the composition ratio of the unreacted monomer and the copolymer produced therefrom, the composition ratio of the unreacted monomer is changed with the progress of the air rice reaction.

For example, in the copolymerization of styrene and acrylonitrile by the water suspension method, when the ratio of acrylonitrile in the initial monomer exceeds 24% by weight, unreacted acryl with the progress of the copolymerization reaction from the relationship with the monomer reactivity ratio The ratio of the amount of unreacted styrene to the amount of ronitrile decreases gradually, so that the copolymer produced at the end of the copolymerization has a very high acrylonitrile content and the composition distribution of the copolymer obtained by the series of copolymerization reactions becomes very wide. .

Such a copolymer having a wide compositional distribution has poor transparency due to poor compatibility between components, and problems such as coloring of the copolymer and deterioration of thermal stability occur due to nonuniformity of components.

Therefore, in order to prepare a copolymer having a desired composition having a uniform composition and excellent quality, a monomer is prepared by initiating a copolymerization reaction at an initial monomer compound composition ratio suitable for the monomer reactivity ratio, and then a monomer having a rapid reaction consumption rate in accordance with the progress of the copolymerization reaction is employed. By continuous or intermittent addition to the solution, the monomer compound composition ratio of the copolymerization reaction system should be kept substantially constant until the copolymerization reaction is terminated.

In addition, the amount of water used as the reaction medium may be 50-500 parts by weight based on 100 parts by weight of the total monomers. If it is less than 50 parts by weight, it is difficult to disperse and remove the dispersing characteristics and heat of reaction, and if it is more than 500 parts by weight, it will adversely affect the dispersion state and require more dispersant, and it will be dispersed during the reaction due to the increase of the amount of unsaturated nitrile monomer dissolved in water. This results in deterioration of the state and a decrease in the content of the nitrile component in the final copolymer and a decrease in the molecular weight. It also leads to particle size non-uniformity and productivity degradation.

The polymerization temperature is usually about 60-110 ° C., and air polymerization is carried out at a pressure of 0.1-5 kg / cm 2 for 2.5-6 hours. Even after the polymerization is almost finished, in the polymerization contents, about 5-20% by weight of the total monomers in which the unreacted monomers are used remain. In addition, since some of the active radicals that do not stop the reaction and residual initiators that did not initiate the reaction remain in the polymerization contents, the unreacted monomers are recovered immediately after the end of the polymerization. The polymerization is carried out in order to prevent unreacted monomers before the recovery of unreacted monomers. If necessary, the polymerization content obtained in the copolymerization process is based on amines, nitrites and quinones. In addition, one or more polymerization inhibitors and / or polymerization delaying agents selected from phenothiazine-based, sulfide-based or carbamate-based may be used.

After completion of the polymerization, the polymer slurry is transferred to the reactor and / or to another separate unreacted monomer recovery device, which is unreacted through a single step or a multi-step process by conventional stripping or recovery. Recover the monomer.

At this time, the stripping temperature is preferably higher than the boiling point of the monomer to be recovered, in particular, above the azeotropy temperature of the water and the monomer, and then vaporized to condense and recovered in the condenser. It is good to keep it short. Usually this time is about 30 minutes-5 hours. Miban is dehydrated, washed and dried in accordance with a conventional method to recover the monomer content is obtained as a granular copolymer.

The copolymer of the aromatic vinyl / unsaturated nitrile compound prepared according to the present invention as described above has a uniform composition and contains a high proportion of saturated nitrile component, so that not only normal mechanical quality but also color stability, transparency, gas barrier property, It is excellent in chemical resistance, thermal stability, etc. and can be used for the production of various molded products, packaging containers, etc. by injection, compression, extrusion molding, and the like.

The nitrile copolymer prepared according to the present invention may be added with a heat stabilizer, an antioxidant, an ultraviolet stabilizer, a flame retardant, an antistatic agent, a colorant, an inorganic filler, and the like, and may include a small amount of other resins as necessary.

In the following Examples, the present invention is described in more detail, but the present invention is not limited to the following Examples unless the gist of the present invention.

Example 1

Inner volume 300 1 A high pressure reactor made of stainless steel with a baffle plate and a stirring device attached to a heating jacket was subjected to the initial introduction of each component in the following formulation and stirred to uniformly suspend the reaction system. The total amount of monomers introduced was 100 kg. The amount of each component added was expressed in parts by weight when the total amount of monomers was 100 parts by weight.

Subsequently, after nitrogen-substituting the reactor, the temperature of the reaction system was raised to 65 ° C, and 0.35 parts by weight of 2,2'-azobisisobutyronitrile dissolved in a small amount of styrene while stirring the reaction system was pressurized with nitrogen to copolymerize the reaction. Was initiated. Immediately after the start of the copolymerization, continuous supply of styrene was started to the reaction system, and 39.8 parts by weight of styrene was continuously supplied for 4.5 hours at a rate proportional to the copolymerization reaction rate. In the meantime, reaction temperature heated up to 85 degreeC. Suspension observed visually through the sight glass attached to the top of the reactor during the reaction was very good.

After continually adding styrene to the reaction system, the unreacted monomer recovery was performed, and then 85 kg of a copolymer was obtained through filtration, washing, and drying which are normal post-treatment steps. The particle size of the obtained copolymer was fairly uniform and the color tone was also good.

This copolymer was processed and evaluated by the method described later. Particle size distribution of the copolymer, after processing the copolymer into pellets (pellets) through the extruder, the physical property test results and other properties as shown in Table 1 as shown in Table 1.

Example 2

Into the same reactor as used in Example 1, the raw materials of the following formulation were initially charged and the reaction system was uniformly suspended. The total amount of added monomer was 100 kg.

Subsequently, after nitrogen-substituting the reactor, the temperature of the reaction system was raised to 65 ° C., and 0.48 parts by weight of 2,2′-azobisisobutyronitrile dissolved in a small amount of styrene while stirring the reaction system was pressurized with nitrogen to carry out a copolymerization reaction. Started. Immediately after the start of the copolymerization, styrene was continuously supplied to the reaction system, and 24.6 parts by weight of styrene was continuously supplied for 4 hours at a rate proportional to the copolymerization reaction rate. In the meantime, reaction temperature heated up to 85 degreeC. Suspension observed visually through the sight glass attached to the top of the reactor during the reaction was very good.

After continually adding styrene to the reaction system, 83 kg of the copolymer was obtained by treating in the same manner as in Example 1). The particle size of the obtained copolymer was fairly uniform and the color tone was also good. The evaluation was performed as in Example 1 and the results are shown in Table 1.

Comparative Example 1

The polymerization was carried out in the same manner as in Example 1 except that the phosphate ester-based dispersant in the initial preparation was omitted and the content of the suspending agent was changed. Initial prescription is as follows.

During the reaction, the suspended state visually observed through the sight glass attached to the upper part of the reactor became worse as the reaction progressed and the conversion rate increased.In the later stages of the reaction, the viscosity of the reaction system increased greatly, resulting in a state of porridge. Was stagnated and agglomerated in the blockage area.

This phenomenon was slightly improved at the end of the continuous supply of styrene and at the end of the reaction. Immediately after completion of the reaction, 83 kg of a copolymer was obtained through an unreacted monomer recovery step and a post-treatment step. The particle size of the copolymer obtained was quite heterogeneous, some of the copolymer was in the form of a very large mass, and the color tone was pale yellowish brown. Evaluation similar to Example 1 was performed and the result is shown in Table 1. FIG.

Comparative Example 2

The polymerization was carried out in the same manner as in Example 2 except that the carboxylic acid anionic surfactant in the initial dosage formulation was omitted and the type and content of the suspending agent were changed. Initial prescription is as follows.

Suspended state visually observed through the sight glass attached to the upper part of the reactor during the reaction became worse as the reaction progressed and the conversion rate increased.In the late stage of the reaction, the viscosity of the reaction system increased greatly, resulting in a dark cream state at the top of the reaction contents. A considerable amount of stagnation was caused by the blockages gathering together.

This phenomenon is only slightly improved at the end of the continuous supply of styrene and at the end of the reaction. Immediately after completion of the reaction, 82 kg of a copolymer was obtained through an unreacted monomer recovery step and a post-treatment step. The particle size of the obtained copolymer was quite uneven, some of the copolymer was in the form of a very large lump, and the color tone was pale yellow brown. Evaluation similar to Example 1 was performed and the result is shown in Table 1. FIG.

Comparative Example 3

The polymerization was carried out in the same manner as in Example 1, except that 0.2 parts by weight of hydroxyethyl cellulose alone was used as a dispersant in the initial dosage formulation. The suspended state during the reaction was similar to that of Comparative Example 2), and 83 kg of the copolymer was obtained after workup. The particle size and appearance of the obtained copolymer were similar to those of Comparative Example 2). Evaluation similar to Example 1 was performed and the result is shown in Table 1. FIG.

[Comparative Example 4]

The polymerization was carried out in the same manner as in Example 1, except that 2.0 parts by weight of calcium hydroxy apatite was used alone as a dispersant in the initial dosage regimen. The suspended state during the reaction deteriorated rapidly as the reaction proceeded, and a considerable amount of the reactor wall and agitation were carried out. Agglomerates stuck to the wings of the rods. The partially obtained copolymer was worked up to obtain 50 kg. Evaluation similar to Example 1 was performed and the result is shown in Table 1. FIG.

Preparation and Characteristic Evaluation of Pearllet Test Specimen

The copolymers obtained in each of the above examples were pellets after the volatiles were removed from the vent section using a single screw extruder. The pellets were prepared using a injection molding machine at 220 ° C. to test the physical properties. Tensile strength, Izod impact strength, heat deflection temperature, fluidity (M.I.), yellowness index and haze were measured for the copolymer and the physical specimen.

In addition, the strength of the AN-AN-AN- triad and SM-SM-SM triad of the copolymer was analyzed using a nuclear magnetic resonance apparatus to confirm the uniformity of the composition distribution. In addition, the particle size distribution of the copolymer was confirmed by sieve test.

Analysis method

Tensile Strength: ASTM D-638

Izod impact strength: ASTM D-256 (notched), 1/4 specimen

Heat Deflection Temperature: ASTM D-648

Flowability (M.L): ASTM D-1238 (220 ℃, 10㎏f)

Yellowness (Y.L): Nihon Densoku Industrial Co., Ltd. Σ 80 type color difference meter, measured according to JIS K 7103

Haze: Nihon Densoku Industrial Co., Ltd. Σ 80 type color difference meter, measured according to JIS K 7105

Composition Analysis: AN-AN-AN and SM-SM-SM Triad Analysis of Copolymers Using Bruker AC-2000MHz ¹³ C NMR

Particle size analysis (Sieve test): 100g of sample was separated by particle size by ultrasonic vibration for 5 minutes using Endagoncott's Octagon 200 sieve analyzer.

Note 4) The result of the particle size distribution analysis is not significant because the comparative example 4) is the result of analysis of the copolymer obtained in some particle state.

Judging from the above Table 1, in the present invention using a combination of an inorganic suspending agent, a carboxylic acid anionic surfactant, and a phosphate ester dispersant as a suspending agent, a styrene-acrylonitrile copolymer having a high content of an unsaturated nitrile compound Suspension stability during the reaction is greatly improved during manufacture, resulting in uniform particle size distribution and composition (reduced components of the AN-AN-AN and SM-SM-SM combinations of the copolymer) and greatly in yellowness, turbidity and other physical properties. It can be seen that the improvement.

As can be seen from the above examples and comparative examples, in the present invention, in preparing a nitrile copolymer having a high content of an unsaturated nitrile compound, the suspending agent used in the polymerization reaction is an inorganic suspending agent or a carboxylic acid anionic surfactant. And the particle size distribution and composition of the copolymer obtained by using a combination of a phosphate ester-based dispersant can be uniform, and yellowness, turbidity, and other physical properties can be greatly improved.

Therefore, by using the method of the present invention, it is possible to extend the use to thermoplastic resins which are excellent in chemical resistance and require stability of color and transparency. In particular, the present invention can be applied to food packaging containers requiring gas barrier properties and applications as matrix resins on refrigerator interiors requiring good quality resistance.

Claims (3)

In preparing a nitrile copolymer having an unsaturated nitrile compound monomer content in the copolymer of 33-80% by weight and an aromatic vinyl monomer content of 20-67% by weight in the suspension polymerization method, 0.005 to 2.5 parts by weight of an inorganic suspending agent, 0.0005 to 0.1 parts by weight of a carboxylic acid anionic surfactant, and 0.0005 to 0.05 parts by weight of a phosphate ester dispersant, based on 100 parts by weight of A method for producing a nitrile copolymer having excellent polymerization stability, characterized in that it is used. The method for producing a nitrile copolymer having excellent polymerization stability according to claim 1, wherein the inorganic suspending agent is tricalcium phosphate or calcium hydroxyapatite. The method for producing a nitrile copolymer having excellent polymerization stability according to claim 1, wherein the phosphate ester dispersant is polyoxyethylene alkyl ether phosphate ester or polyoxyethylene alkyl aryl ether phosphate ester.