KR102538844B1 - Method for preparing vinyl aromatic compound-vinylcyan compound copolymer and method for preparing thermoplastic resin composition comprising the copolymer - Google Patents

Abstract

The present invention relates to a method for preparing an aromatic vinyl compound-vinyl cyan compound copolymer and a method for preparing a thermoplastic resin composition comprising the same, and more particularly, to a method for preparing an aromatic vinyl compound and a vinyl cyan compound having an average particle diameter of 75 μm or less during suspension polymerization. By adding aromatic vinyl compound-vinyl cyan compound fine particles to increase the viscosity of the reactant, and by adding a dispersing agent and a dispersing aid in a specific ratio, droplets are stabilized and fine droplets are effectively reduced to improve particle size distribution. It relates to a method for preparing an aromatic vinyl compound-vinyl cyan compound copolymer capable of obtaining a high molecular weight aromatic vinyl compound-vinyl cyan compound copolymer and a method for preparing a thermoplastic resin composition comprising the same.

Description

A method for preparing an aromatic vinyl compound-vinyl cyan compound copolymer and a method for preparing a thermoplastic resin composition comprising the same

The present invention relates to a method for preparing an aromatic vinyl compound-vinyl cyan compound copolymer and a method for preparing a thermoplastic resin composition comprising the same, and more particularly, during suspension polymerization of an aromatic vinyl compound and a vinyl cyan compound, droplets are formed. Method for preparing an aromatic vinyl compound-vinyl cyan compound copolymer capable of obtaining a high molecular weight aromatic vinyl compound-vinyl cyan compound copolymer having an improved particle size distribution by stabilizing and effectively reducing fine droplets, and preparation of a thermoplastic resin composition comprising the same It's about how.

Aromatic vinyl compound-vinyl cyan compound copolymer, represented by styrene-acrylonitrile copolymer (SAN resin), is widely used in various fields such as electric and electronic products and automobile parts because of its excellent transparency, chemical resistance and rigidity. It is also used for purposes such as improving the moldability of ABS resin or reinforcing heat resistance due to its excellent compatibility with resin.

As described above, it is preferable to prepare the SAN resin used for compounding with the ABS resin to have an average particle diameter similar to that of the ABS resin in terms of securing physical property balance and improving moldability.

Conventional SAN resins are produced by methods such as bulk polymerization, suspension polymerization, and emulsion polymerization. In the case of manufacturing SAN resins by bulk polymerization, productivity is high in a continuous process and polymerization is possible without additives, so the copolymer has an advantage of high purity. However, since the viscosity of the reactants is very high, the degree of polymerization is relatively low and it is difficult to control the heat of reaction.

In addition, when SAN resin is prepared by emulsion polymerization, since water is used as a solvent, it is easy to control the reaction heat and is advantageous in controlling the particle size. As the emulsifier was added, impurities were generated and the purity was low, and there were problems such as deterioration of physical properties due to the residual emulsifier.

In order to compensate for the above problems, a method for preparing a SAN resin through suspension polymerization has been proposed. However, suspension polymerization is a method of preparing a polymer by dispersing an insoluble monomer present in a water-soluble dispersion medium with vigorous stirring through physical stirring, and as the reaction proceeds, the viscosity of the reactant increases rapidly, resulting in relatively poor polymerization stability. As droplets with various particle size characteristics are formed and, as a result, fine particles or coarse particles are formed together, the particle size distribution is large, and physical properties are not uniform. For this reason, excessive addition of a dispersant was inevitable during suspension polymerization in order to improve polymerization stability and lower particle size distribution.

Therefore, when preparing a SAN resin for compounding with an ABS resin by suspension polymerization, a technology capable of improving polymerization stability and finally providing a high molecular weight SAN resin having a high degree of polymerization and an improved particle size distribution is required.

Korean registered patent 1996-0003648 B1

In order to solve the problems of the prior art as described above, the object of the present invention is to provide a method for preparing a high molecular weight aromatic vinyl compound-vinyl cyan compound copolymer having a high degree of polymerization and an improved particle size distribution while improving polymerization stability through suspension polymerization. And furthermore, an object of the present invention is to provide a method for producing a thermoplastic resin composition comprising the copolymer prepared as described above.

In addition, an object of the present invention is to provide a high-quality aromatic vinyl compound-vinyl cyan compound copolymer with high productivity.

The above and other objects of the present invention can all be achieved by the present invention described below.

In order to achieve the above object, the present invention provides an aromatic vinyl compound-vinyl cyan compound copolymer having an average particle diameter of 75 μm or less by suspension polymerization of an aromatic vinyl compound and a vinyl cyan compound to prepare an aromatic vinyl compound-vinyl cyan compound pine (fine) particles, a dispersing agent and a dispersing agent are added, and the fine particles are added in an amount of 3 to 17 parts by weight based on a total of 100 parts by weight of the aromatic vinyl compound and the vinyl cyan compound, and the weight ratio of the dispersing agent to the dispersing agent is 60 to 450 It provides a method for producing an aromatic vinyl compound-vinyl cyan compound copolymer, characterized in that.

In addition, the present invention is a thermoplastic comprising the steps of kneading and extruding the aromatic vinyl compound-vinyl cyan compound copolymer and the aromatic vinyl compound-conjugated diene rubber-vinyl cyan compound copolymer prepared according to the above production method. A method for preparing a resin composition is provided.

According to the present invention, during suspension polymerization, aromatic vinyl compound-vinyl cyan compound fine particles having an average particle diameter of 75 μm or less are added to increase the viscosity of the reactant, and droplets are formed by adding a dispersant and a dispersing aid in a specific ratio. There is an effect of providing a high molecular weight aromatic vinyl compound-vinyl cyan compound copolymer having an improved particle size distribution with high productivity by stabilizing and effectively reducing fine droplets.

In addition, according to the present invention, a high polymerization stability is provided even when a small amount of a dispersant and a dispersing aid is used.

In addition, the aromatic vinyl compound-vinyl cyan compound copolymer according to the present invention is compounded with an aromatic vinyl compound-conjugated diene rubber-vinyl cyan compound copolymer to be used in manufacturing various molded articles, thereby contributing to product productivity and quality improvement.

1 is a photograph showing the stability of droplets dispersed in a suspension prepared according to an embodiment of the present invention.
Figure 2 is a photograph showing the stability of the droplets dispersed in the suspension prepared according to Comparative Examples 1 to 6.
Figure 3 is a result of measuring the suspension prepared in Examples and Comparative Examples with an optical microscope.
4 is a graph showing the results of particle size distribution analysis of SAN beads prepared in Examples and Comparative Examples.
5 is a photograph showing that agglomerates are generated due to disruption of dispersion stability of droplets when suspension polymerization is performed according to Comparative Example 4.
6 is a photograph showing the stability of droplets dispersed in suspensions prepared according to Reference Examples 1 to 3.
Figure 7 is a photograph showing the stability of the droplets dispersed in the suspension according to the type of dispersion aid.

Hereinafter, a method for preparing the aromatic vinyl compound-vinyl cyan compound copolymer of the present disclosure and a method for preparing a thermoplastic resin composition including the same will be described in detail.

When preparing a styrene-acrylonitrile copolymer through suspension polymerization, the present inventors add styrene-acrylonitrile fine particles having an average particle diameter of 75 μm or less and dissolve them in a suspension polymerization reaction solution to increase the viscosity of the reactant, and to obtain a dispersant and When suspension polymerization is performed by adding a dispersing agent in a specific ratio, fine droplets are reduced and stabilized, so the particle size distribution can be improved. After confirming the points that could be secured, based on this, further efforts were made to complete the present invention.

The method for producing an aromatic vinyl compound-vinyl cyan compound copolymer of the present invention, for example, in preparing an aromatic vinyl compound-vinyl cyan compound copolymer by suspension polymerization of an aromatic vinyl compound and a vinyl cyan compound, having an average particle diameter of 75 μm or less Aromatic vinyl compound-vinyl cyan compound fine particles, a dispersing agent and a dispersing agent are added, and the fine particles are added in an amount of 3 to 17 parts by weight based on the total of 100 parts by weight of the aromatic vinyl compound and vinyl cyan compound, It may be characterized in that the weight ratio of the dispersant to 60 to 450, in this case, the high molecular weight aromatic vinyl compound-vinyl cyan compound copolymer having an improved particle size distribution by stabilizing droplets and effectively reducing fine droplets with high productivity can provide

Hereinafter, a method for preparing the aromatic vinyl compound-vinyl cyan compound copolymer of the present disclosure will be described in detail.

The method for preparing the copolymer is characterized in that, during suspension polymerization of an aromatic vinyl compound and a vinyl cyan compound, aromatic vinyl compound-vinyl cyan compound fine particles having an average particle diameter of 75 μm or less are added. It dissolves in the vinyl cyan compound to increase the viscosity of the suspension polymerization reaction product, thereby reducing the generation of fine droplets in the suspension polymerization reaction product, thereby providing an effect of uniformizing the particle size distribution of the final resin by forming droplets of uniform size.

The aromatic vinyl compound-vinyl cyan compound fine particles may have an average particle diameter of, for example, 75 μm or less, 20 to 75 μm, and preferably 30 to 70 μm or 40 to 60 μm. In this case, the monomer An aromatic vinyl compound-vinyl cyan compound copolymer having excellent dissolution efficiency for the compound and excellent polymerization stability, and a small particle size distribution can be provided with high productivity.

Unless otherwise specified, the average particle diameter of polymers including aromatic vinyl compound-vinyl cyan compound fine particles in the present description is obtained by diluting the polymer in deionized water at 1% by weight to prepare a sample, and then using laser diffraction. It is an average particle diameter (based on weight average) measured in a wet mode using a particle size analyzer (Sympatec's HELOS particle size analyzer).

The fine particles may be included in an amount of 3 to 17 parts by weight, 5 to 15 parts by weight, or 7 to 15 parts by weight, preferably 10 to 15 parts by weight, based on 100 parts by weight of the total of the aromatic vinyl compound and the vinyl cyan compound. There is an advantage in that the stability of the droplet is improved without reducing the process efficiency because the rate of dissolution in the monomer is excellent within this range. In particular, when the fine particles are added in excess of 20 parts by weight, it takes a considerable amount of time to completely dissolve the fine particles, which is not suitable for the polymerization process, and mixing stability may be lowered if the initial viscosity is too high.

The fine particles may have a weight average molecular weight of, for example, 300,000 to 400,000 g / mol or greater than 300,000 g / mol to less than 400,000 g / mol, preferably 350,000 to 400,000 g / mol, within this range within this range Polymerization stability is excellent, and the finally obtained aromatic vinyl compound-vinyl cyan compound copolymer has an even and uniform average particle diameter.

Unless otherwise specified, the weight average molecular weight of the fine particles in this description is a value measured by gel permeation chromatography (model name: PL GPC220, manufacturer: Agilent Technologies), specifically, fine particles in tetrahydrofuran (THF) After melting and preparing, the measurement was performed at 40° C., and polystyrene was used as a standard material.

The dispersant is used for the purpose of stably dispersing the droplets by adsorbing on the surface of the droplets in the suspension polymerization reactant, and preventing particles from aggregating to form agglomerates as the reaction proceeds.

The dispersant may be added in an amount of, for example, 0.1 to 5.0 parts by weight or 0.5 to 3.0 parts by weight, based on 100 parts by weight of the total of the aromatic vinyl compound and the vinyl cyan compound, and preferably 0.5 to 2.0 parts by weight, 0.5 to 1.5 parts by weight, or It may be added in an amount of 1 to 2.0 parts by weight, and within this range, an aromatic vinyl compound-vinyl cyan compound copolymer having a desired size and a small particle size distribution can be obtained.

The dispersant may be, for example, at least one selected from among phosphate-based dispersants and carbonate-based dispersants, and preferably may be phosphate-based dispersants, and in this case, polymerization stability is excellent.

In a specific example, the phosphate-based dispersant may be at least one selected from tricalcium phosphate, calcium hydrogen phosphate, calcium dihydrogen phosphate, hydroxyapatite, trimagnesium phosphate, aluminum phosphate, and zinc phosphate, and the carbonate-based dispersant is calcium It may be at least one selected from carbonate and magnesium carbonate, and a particularly preferred dispersing agent among them may be tricalcium phosphate.

The dispersing aid is adsorbed on the surface of the dispersant to further stabilize the droplets, and serves to prevent particles from aggregating to form agglomerates as the reaction proceeds.

The dispersion aid may be added in an amount of, for example, 0.001 to 0.1 parts by weight, 0.005 to 0.05 parts by weight, preferably 0.005 to 0.03 parts by weight, 0.007 to 0.015 parts by weight, based on 100 parts by weight of the aromatic vinyl compound and vinyl cyan compound in total. It may be added in an amount of 0.01 to 0.02 parts by weight, and within this range, the dispersion stability of the droplets is excellent and the particle size distribution can be improved.

The dispersion aid may be, for example, a phosphate-based dispersion aid, and in this case, there is an advantage in that the dispersion stability of the liquid droplets is excellent.

As an example, the phosphate-based dispersion aid may be polyoxyalkylene alkyl ether phosphate, and as a specific example, may be polyoxyethylene alkyl ether phosphate. In this case, the dispersion stability of droplets is excellent and the particle size distribution is improved. there is.

The weight ratio (y/x) of the dispersing agent (y) to the dispersing aid (x) may be, for example, 60 to 450 or 80 to 300, preferably 90 to 250 or 100 to 200, within this range. A copolymer having excellent polymerization stability and a desired average particle size can be obtained. When the weight ratio of the dispersing agent to the dispersing agent is less than 60, there is a problem in that dispersion stability is very low and agglomerates are formed. There may be a problem in that the yield decreases due to the generation of a large amount of particles.

The aromatic vinyl compound may be, for example, at least one selected from styrene, α-methylstyrene, p-methylstyrene, t-butyl styrene, halogen-substituted styrene, dimethylstyrene, ethyl styrene, and the like, and preferably styrene and α-methyl It may be at least one selected from styrene.

The vinyl cyanide compound may be, for example, at least one selected from acrylonitrile, methacrylonitrile, ethacrylonitrile, and the like, and preferably includes acrylonitrile.

The weight ratio of the aromatic vinyl compound and the vinyl cyan compound may be, for example, 20:80 to 80:20 or 30:70 to 70:30, preferably 60:40 to 80:20 or 65:35 to 75:25. Within this range, the finally obtained copolymer has excellent physical property balance, and provides advantages such as excellent moldability when compounding with the aromatic vinyl compound-conjugated diene rubber-vinyl cyan compound copolymer.

As a specific example, the suspension polymerization is performed by stirring a suspension polymerization reaction product including an aromatic vinyl compound and a vinyl cyan compound, an aromatic vinyl compound-vinyl cyan compound fine particles having an average particle diameter of 75 μm or less, a dispersing agent, a dispersing aid, and an initiator in water. forming droplets, and raising the temperature to perform suspension polymerization.

The stirring may be performed at, for example, 200 to 600 rpm, 300 to 500 rpm, or 400 to 600 rpm, and in this case, a copolymer having a desired average particle diameter and a uniform particle size can be obtained.

The suspension polymerization may be carried out at a temperature of, for example, 80 to 130 °C, 90 to 110 °C or 80 to 90 °C, and in this case, the polymerization stability is excellent and the polymerization efficiency is advantageous. The suspension polymerization temperature may vary depending on the type of initiator used, and for example, it is advantageous in terms of reaction efficiency to perform the polymerization at a temperature about 5 to 10° C. above the 10-hour half-life temperature of the initiator.

The initiator is not particularly limited as long as it is a type commonly used in the art and may be appropriately selected, preferably benzoyl peroxide, dipentyl peroxide, di-3,5,5-trimethyl hexanoyl peroxide, t-butylper Benzoate, lauryl peroxide, dicumyl peroxide, t-butylperoxy pivalate, 1,1,3,3-tetramethylbutylperoxy neodecanoate, t-butylperoxy neodecanoate, 1, 1-di(t-butylperoxy)cyclohexane; It may be one or more selected from among.

The initiator may be added in an amount of 0.01 to 0.7 parts by weight or 0.03 to 0.5 parts by weight, for example, based on 100 parts by weight of the aromatic vinyl compound and vinyl cyan compound in total, and within this range, the polymerization efficiency is excellent and the particle size distribution is uniform. to provide.

During the suspension polymerization, additives such as polymerization regulators, chain transfer agents, pH regulators, scale inhibitors, electrolytes, etc. may be optionally added as needed in addition to the above-mentioned active ingredients, the types and contents of which are not particularly limited and are known in the art. It can be used in conventional types and contents known in

The aromatic vinyl compound-vinyl cyan compound copolymer prepared as described above may have an average particle diameter of, for example, 80 to 300 μm or 85 to 200 μm, and preferably 90 to 150 μm. In this case, the aromatic vinyl compound By compounding with the compound-conjugated diene rubber-vinyl cyan compound copolymer, a resin composition excellent in physical property balance and moldability can be provided.

The copolymer prepared according to the method for preparing the aromatic vinyl compound-vinyl cyan compound copolymer of the present disclosure may be provided as a thermoplastic resin composition by compounding with an aromatic vinyl compound-conjugated diene rubber-vinyl cyan compound copolymer. A method for producing the thermoplastic resin composition of the substrate will be described.

The method for preparing the thermoplastic resin composition includes, for example, the steps of kneading and extruding the aromatic vinyl compound-vinyl cyan compound copolymer and the aromatic vinyl compound-conjugated diene rubber-vinyl cyan compound copolymer prepared as described above. It is characterized by, and in this case, it provides excellent advantages such as impact resistance and formability.

The aromatic vinyl compound and vinyl cyan compound of the aromatic vinyl compound-conjugated diene rubber-vinyl cyan compound copolymer may be, for example, the same as the aromatic vinyl compound and vinyl cyan compound included in the aromatic vinyl compound-vinyl cyan compound copolymer. there is.

The conjugated diene rubber may be, for example, at least one selected from butadiene polymers, butadiene-styrene copolymers, butadiene-acrylonitrile copolymers, ethylene-propylene copolymers, etc., and preferred examples are butadiene polymers or butadiene-styrene copolymers. can

For example, the composition may contain 20 to 80% by weight or 30 to 70% by weight of an aromatic vinyl compound-vinyl cyan compound copolymer; and 20 to 80 wt% or 30 to 70 wt% of the aromatic vinyl compound-conjugated diene rubber-vinyl cyan compound copolymer, and within this range, excellent physical property balance and moldability are provided.

The kneading and extruding is not particularly limited as long as it is a method and condition commonly used in the art, and may be preferably carried out at 150 to 300 ° C. and 100 to 500 rpm or 200 to 300 ° C. and 200 to 300 rpm. It is not limited.

Hereinafter, preferred embodiments are presented to aid understanding of the present invention, but the following examples are merely illustrative of the present invention, and various changes and modifications are possible within the scope and spirit of the present invention. It is obvious to those skilled in the art, It goes without saying that these variations and modifications fall within the scope of the appended claims.

[Example]

Example 1

In the reactor, 140 parts by weight of ion-exchanged water, 70 parts by weight of styrene, 30 parts by weight of acrylonitrile, 0.035 parts by weight of 1,1-di(t-butylperoxy)cyclohexane as an initiator and 0.025 parts by weight of dicumyl peroxide as a suspending agent 0.7 parts by weight of tricalcium phosphate, 0.007 parts by weight of polyoxyethylene alkyl ether phosphate (RS-710) as a dispersing aid, and 0.08 parts by weight of t-dodecyl mercaptan as a molecular weight modifier were added. After raising the temperature of the reactor to 95 ℃, polymerization was carried out for 4 hours. At this time, the polymerization conversion rate was about 80% or more, and the temperature was raised to 130 ° C., and polymerization was further conducted for 2 hours including the temperature increase time. After the polymerization was completed, after cooling the temperature inside the reactor to room temperature, formic acid was added to the reactor so that the pH of the polymerization slurry was less than 2.7, and then the SAN copolymer in the form of beads was prepared by dehydration and drying.

Examples 2 to 12

The experiment was performed in the same manner as in Example 1 except that the ratio of the dispersant/dispersion aid or the amount of fine particles injected in Example 1 was changed as shown in Table 1 below.

Comparative Examples 1 to 8

The experiment was performed in the same manner as in Example 1 except that the ratio of the dispersant/dispersion aid or the amount of fine particles injected in Example 1 was changed as shown in Table 1 below.

Example 1

29 parts by weight of ABS resin (DP270E product of LG Chem) and 61 parts by weight of bulk polymerized SAN resin (97HC product of LG Chem) were mixed with 10 parts by weight of the SAN beads prepared in Example 2, and they were kneaded and extruded to form pellets. A thermoplastic resin composition was prepared, and the pellet was injected to prepare a specimen for measuring physical properties.

[Test Example]

The properties of the beads prepared in the above Examples and Comparative Examples were measured by the following method, and the results are shown in Table 1 and Figures 1 to 4 below.

Specifically, Table 1 shows the types and contents of the dispersing agent and dispersing aid added in Examples 1 to 3 and Comparative Examples 1 to 5, the content of fine particles, the viscosity of the suspension, and the average particle diameter and particle size distribution of the final polymer.

Figure 1 is a photograph showing the stability of the suspension prepared in Examples and Comparative Examples, Figure 2 is the result of measuring the suspension prepared in Examples and Comparative Examples with an optical microscope, Figure 3 is prepared in Examples and Comparative Examples FIG. 4 is a graph showing the results of particle size distribution analysis of SAN beads, and FIG. 4 is a photograph showing that agglomerates are generated due to the stability of the suspension being destroyed when suspension polymerization is performed according to Comparative Example 4.

*Viscosity measurement

The viscosity of the suspension was measured using a Brookfield viscometer, and specifically, the viscosity was measured at 12 rpm using a Brookfield DV2T LV TJ0 model equipment at 25 °C.

*Average particle diameter and particle size distribution measurement

After preparing a sample by diluting the polymer to 1% by weight in deionized water, average particle diameter (based on weight average) and span value in wet mode using a particle size analyzer (Sympatec's HELOS particle size analyzer) through laser diffraction was measured. The span value is a value indicating the width of the particle size distribution, and the larger the particle size distribution width, the larger the span value.

* Droplet stability evaluation

A portion of the initial polymerization suspension was stirred with a shaker for 20 minutes, and after 5 minutes, the state of the droplets was visually observed and evaluated according to the following criteria.

○ (Stable): When the droplets remain uniformly dispersed even after 5 minutes after stirring

△ (partially stable): When the dispersion state of the droplets is partially maintained and complete layer separation does not occur, but the dispersion stability of the droplets is low and the droplets are large in size and some monomer layers are separated.

Χ (unstable): When the droplets do not maintain a dispersed state within 5 minutes and the layer separation occurs into a transparent monomer layer and a white droplet

*Optical microscope measurement

In order to more specifically confirm the state of the droplets, a portion of the initial polymerization suspension was taken and the droplets were observed under an optical microscope.

dispersant dosage
[parts by weight] Amount of dispersing aid [parts by weight] Dispersant/dispersion aid ratio Fine particle dosage [parts by weight] Viscosity [cP] droplet
stability Average particle size [㎛] span value Example 1 0.7 0.007 100 10 45 ○ 130.11 0.74 Example 2 1.3 0.013 100 10 45 ○ 115.97 0.79 Example 3 2.0 0.020 100 10 45 ○ 96.69 0.77 Example 4 1.3 0.015 87 10 45 ○ 160.18 0.80 Example 5 1.3 0.009 144 10 45 ○ 109.87 0.78 Example 6 1.3 0.006 217 10 45 ○ 100.54 0.79 Example 7 1.3 0.005 260 10 45 ○ 94.78 0.82 Example 8 1.3 0.004 325 10 45 ○ 85.65 0.85 Example 9 1.3 0.003 433 10 45 ○ 92.28 0.87 Example 10 1.3 0.013 100 5 10.8 ○ 110.25 0.79 Example 11 1.3 0.013 100 15 62.5 ○ 183.59 0.81 Example 12 1.3 0.013 100 3 6.2 ○ 102.44 0.85 Comparative Example 1 0.7 0.007 100 0 1.95 Χ 118.19 0.89 Comparative Example 2 1.3 0.013 100 0 1.95 Χ 100.08 0.90 Comparative Example 3 2.0 0.020 100 0 1.95 ○ 78.45 0.91 Comparative Example 4 1.3 0.025 52 0 1.95 Χ - - Comparative Example 5 1.3 0.025 52 10 45 △ 550.76 0.88 Comparative Example 6 1.3 0.003 433 0 1.95 ○ 87.55 0.92 Comparative Example 7 1.3 0.013 100 20 89.6 △ 221.57 0.83 Comparative Example 8 1.3 0.013 100 One 2.12 ○ 100.75 0.89

(In Table 1, each of the input amounts of the dispersant, dispersant aid, and fine particles is based on the total of 100 parts by weight of styrene and acrylonitrile added during suspension polymerization.)

As shown in Table 1, in the case of Examples 1 to 12 according to the present invention, the ratio of the dispersing agent and the dispersing aid is controlled and added within a specific range, and the fine particles are dissolved in the monomer to increase the viscosity of the suspension. It can be seen that the droplet stability is excellent, the average particle diameter of the SAN beads obtained according to the present invention is appropriate, and the particle size distribution is improved.

In particular, when the fine particles were added in an amount of 5 to 10 parts by weight and the ratio of the dispersant/dispersion aid was 100 to 200, the stability of the droplet was more excellent, and SAN beads having a desired average particle diameter could be obtained, and the particle size distribution was further improved, confirming that it could greatly contribute to productivity improvement.

On the other hand, the other conditions were tested in the same manner as in Examples, but in the case of Comparative Example 8 in which fine particles were added at 1 part by weight, it was confirmed that the effect of increasing the viscosity of the suspension was low and the particle size distribution was not improved, and the fine particles were In the case of Comparative Example 7 added at 20 parts by weight, it was difficult to mix the reactants because the initial viscosity was too high, and it took a considerable amount of time to completely dissolve the fine particles, reducing process efficiency and confirming that it was not suitable for the purpose of the present invention .

On the other hand, in the case of Comparative Examples 1 to 3 in which the addition of the fine particles was omitted, the polymerization stability was poor even though the ratio of the dispersant/dispersion aid was within the range of the present application, and the average particle diameter was relatively small and the particle size distribution was wide compared to the examples. .

In addition, when the addition of the fine particles is omitted and the ratio of the dispersant/dispersion aid is as low as 52 (Comparative Example 4), an excessive amount of the dispersant is added and the layer inversion phenomenon occurs, that is, the monomer droplets are dispersed in water. Suspension polymerization could not be carried out because water droplets of an unformed aqueous phase component were formed.

In addition, even if the fine particles are introduced within the range of the present application, when the ratio of the dispersant/dispersion aid is as low as 52 (Comparative Example 5), the stability of the droplets is lower than that of Examples, the average particle diameter of the beads is quite large, and the effect of improving the particle size distribution is somewhat I was able to confirm what was missing.

In addition, in the case of Comparative Example 6 where the experiment was performed under the same conditions as in Example 9, but the introduction of fine particles was omitted, the dispersion stability of the droplets was excellent, but the particle size distribution was not improved due to the large span value. .

1 and 2 are photographs showing the state of droplets 5 minutes after taking a portion of the initial polymerization suspension and stirring under the same conditions to evaluate the stability of droplets prepared according to Examples and Comparative Examples, respectively. 3 is an optical microscope measurement result of taking the suspensions of Example 1 and Comparative Example 1 in order to more accurately observe the state of the droplet. The left side is the optical microscope measurement result for Example 1 and the right side is Comparative Example 1. Figure 4 shows the average particle diameter and particle size distribution analysis results of Example 1 and Comparative Example 1.

1 to 4, in the case of the present invention, the particle size distribution of the droplets is relatively small compared to the comparative example, and as a result, the particle size distribution is significantly improved compared to the comparative example. .

In addition, in the case of Comparative Example 4, which was tested in the same way as in Example 2, except that the amount of the dispersing agent was increased to 0.025 parts by weight (the ratio of the dispersing agent / dispersing agent was 52), the dispersion stability of the droplets was very low to obtain SAN beads. Couldn't. In this regard, referring to FIG. 5, when the ratio of the dispersant/dispersion aid is as low as 52, as in Comparative Example 4, it was confirmed that agglomerates were formed due to the destruction of the dispersion stability of the droplets.

On the other hand, when fine particles are not introduced and the ratio of dispersant/dispersion aid is increased to 400 or more (Comparative Example 6), the dispersion stability of droplets is good, but it was confirmed that fine fine droplets are generated in excess, and fine particles The average particle diameter of the SAN beads is low compared to Example 9, in which the other conditions are equivalent except for input, does not contribute to improving the particle size distribution, and the yield of SAN beads having the desired average particle diameter is very low due to excessive collection of fine particles confirmed that

Summarizing the above experimental results, when SAN fine particles are added during suspension polymerization and the ratio of the dispersant/dispersion aid is adjusted and added within a specific range, the monomer droplets in the suspension are stably dispersed and this stability can be maintained for a long time, Ultimately, it was confirmed that SAN beads of the desired size can be provided with high productivity and can greatly contribute to improving the particle size distribution.

In addition, the present inventors prepared a resin composition by compounding the SAN beads prepared in Example 2 with conventional bulk polymerization SAN resin and ABS resin (Use Example 2), which is bulk polymerization SAN without mixing and applying SAN beads Resin composition prepared by compounding with resin and ABS resin and impact strength (43 kgfcm/cm ² level when the specimen thickness is 1/8"), tensile strength (480 MPa or more), tensile elongation (33% or more), flexural strength ( 780 MPa or more) and glossiness (45° measurement, 89 GU or more) were confirmed to be at the same level.

Unless otherwise specified in this description, impact strength is a value measured at room temperature according to ASTM D256, tensile strength and tensile elongation are values measured according to ASTM D638, flexural strength is a specific value according to ASTM D790, and gloss The figure is measured at an angle of 45° using a glossmeter.

[Reference example]

In order to confirm the stability of droplets with or without the addition of a dispersion aid and SAN fine particles, the following test was performed. Each of Reference Examples 1 to 3 is a suspension prepared in the same manner as in the above Example, except that a dispersing agent, a dispersing aid and fine particles were added under the conditions shown in Table 2 below. The droplet stability evaluation results for Reference Examples 1 to 3 are shown in FIG. 6 .

dispersant dosage
[parts by weight] Amount of dispersing aid [parts by weight] Fine particle dosage [parts by weight] Reference Example 1 1.3 0.005 - Reference Example 2 1.3 - - Reference Example 3 1.3 0.005 10

In FIG. 6, ① is a photograph immediately after stirring (200 rpm) the suspension prepared in Reference Example 1 for 30 minutes, ② is a photograph after stirring (200 rpm) the suspension prepared in Reference Example 2 for 30 minutes, A photograph after lapse of minutes, ③ is a photograph after stirring (200 rpm) of the suspension of Reference Example 1 for 30 minutes, and a photograph after 5 minutes have elapsed, ④ is a photograph after stirring (200 rpm) of the suspension of Reference Example 3 for 30 minutes , This is a picture after 5 minutes have elapsed.

Referring to FIG. 6, when the introduction of the dispersing aid was omitted (see ②), it was confirmed that the dispersion stability of the droplets was somewhat lowered and foam was formed. In addition, referring to ③ and ④ in FIG. 5, when a dispersing agent and a dispersing aid are added in a specific ratio and fine particles are added, it can be confirmed that the dispersion stability of the droplets is improved due to the viscosity improvement.

In order to evaluate the stability of the suspension according to the type of dispersion aid, the following additional tests were conducted, and the results are shown in FIG. 7 . In FIG. 7, Ref is a suspension without adding a dispersing aid, SLS is a dispersing aid with sodium lauryl sulfate added, SDBS is a dispersing aid with sodium dodecyl benzene sulfonate added, and RS-710 is a dispersing aid. This is a photograph immediately after stirring at 200 rpm for 30 minutes after preparation of the suspension.

Referring to FIG. 7, when sodium lauryl sulfate or sodium dodecyl benzene sulfonate is added as a dispersing aid, the dispersion stability of droplets is lowered compared to the addition of a phosphate-based dispersing agent, and an excessive amount of foam is formed. confirmed that it is. This foam remains on the inner wall of the reactor to form scale, which causes problems in productivity and process efficiency.

Claims (10)

In preparing an aromatic vinyl compound-vinyl cyan compound copolymer by suspension polymerization of an aromatic vinyl compound and a vinyl cyan compound,
During the suspension polymerization, aromatic vinyl compound-vinyl cyan compound fine particles having an average particle diameter of 75 μm or less, a dispersing agent and a dispersing aid are added,
Adding the fine particles in an amount of 3 to 17 parts by weight based on a total of 100 parts by weight of the aromatic vinyl compound and the vinyl cyan compound,
The weight ratio of the dispersing agent to the dispersing aid is 60 to 450,
The aromatic vinyl compound-vinyl cyan compound copolymer is characterized in that the average particle diameter is 85 to 200㎛
A method for producing an aromatic vinyl compound-vinyl cyan compound copolymer. According to claim 1,
The fine particles are characterized in that the weight average molecular weight of 300,000 to 400,000g / mol
A method for producing an aromatic vinyl compound-vinyl cyan compound copolymer. delete According to claim 1,
The dispersant is characterized in that the phosphate-based dispersant
A method for producing an aromatic vinyl compound-vinyl cyan compound copolymer. According to claim 1,
Characterized in that the dispersant is added in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the aromatic vinyl compound and the vinyl cyan compound in total.
A method for producing an aromatic vinyl compound-vinyl cyan compound copolymer. According to claim 1,
Characterized in that the dispersion aid is a phosphate-based dispersion aid
A method for producing an aromatic vinyl compound-vinyl cyan compound copolymer. According to claim 6,
Characterized in that the phosphate-based dispersing aid is polyoxyalkylene alkyl ether phosphate
A method for producing an aromatic vinyl compound-vinyl cyan compound copolymer. According to claim 1,
Characterized in that the dispersion aid is added in an amount of 0.001 to 0.1 parts by weight based on 100 parts by weight of the aromatic vinyl compound and vinyl cyan compound in total.
A method for producing an aromatic vinyl compound-vinyl cyan compound copolymer. According to claim 1,
Characterized in that the weight ratio of the aromatic vinyl compound and the vinyl cyan compound is 20:80 to 80:20
A method for producing an aromatic vinyl compound-vinyl cyan compound copolymer. An aromatic vinyl compound-vinyl cyan compound copolymer and an aromatic vinyl compound-conjugated diene rubber-vinyl cyan compound copolymer prepared according to any one of claims 1 to 2 or 4 to 9, characterized in that it comprises the steps of kneading and extruding
A method for producing a thermoplastic resin composition.

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