KR20020048587A - Method of Preparing Expandable Styrene Resin Having Narrow Particle Size Distribution - Google Patents

Abstract

PURPOSE: Provided is a method for preparing a foam styrene resin having an excellent particle size distribution, which reduce the production cost by using a little suspension stabilizer. CONSTITUTION: The method comprises introducing magnesium phosphate obtained by reacting magnesium chloride(MgCl2) and sodium phosphate(Na4(P2O7)2) during suspension polymerization of styrene monomer, sodium polyacrylate which is a water soluble, interface-adsorbing polymer, formaldehyde condensate of sodium alkylnaphthalene sulfonate which is a fat-soluble surfactant, and an electrolyte to obtain 99% or more of particles having a size of 0.5-1.2 mm. The electrolyte is selected from the group consisting of nitrate, sulfate, carbonate, and benzoate.

Description

Method for preparing expandable styrene resin with excellent particle size distribution {Method of Preparing Expandable Styrene Resin Having Narrow Particle Size Distribution}

Field of invention

The present invention relates to a method for producing an expandable styrene resin having excellent particle size distribution. More specifically, the present invention relates to a production method for obtaining 99% or more of expandable styrene resin particles having a particle size of 0.5 to 1.2 mm by suspension polymerization method.

Background of the Invention

Generally, the size of the expandable styrene resin particles produced by the suspension polymerization method is 0.1 to 2.0 mm, of which resin particles having a particle diameter of 0.5 to 1.2 mm are mainly used in the final product. This is because in the case of expandable styrene resin particles of 0.5 mm or less or 1.2 mm or more, volatilization of the impregnated blowing agent is too fast or too late so that control of foaming and molding properties is not easy.

As described above, the suspension polymerization method used in the present invention is a method of obtaining a polymer by adding a dispersion medium and a monomer under vigorous stirring and then adding an appropriate suspension stabilizer to obtain a final product having a particle size of approximately 0.1 to 2.0 mm. It is distinguished from emulsion polymerization and dispersion polymerization by the size of the obtained product.

The main role of the suspension stabilizer used during the suspension polymerization to produce the expanded styrene resin particles is to prevent the coalescence or abnormal aggregation of the polymer residues and to smoothly process the heat of polymerization, but from the viewpoint of controlling the particle size, It controls the unity rate and cleavage rate of.

In other words, the conventional suspension polymerization method is a method of producing the final polymer particles of the desired size through the growth of the sum of the polymer residues using the suspension stabilizer during the polymerization process, and the particle size distribution is very wide as the particles grow. It is done.

Therefore, various suspension stabilizers are used to produce the final polymer particles of the desired size in order to overcome such a problem, such conventional techniques are US Patent No. 4,036,794, US Patent No. 5,086,079, US Patent No. 5,290,819 And Japanese Patent Application Laid-Open No. Hei 4-320403, Japanese Patent Application Laid-Open No. Hei 5-214152, and Japanese Patent Application Laid-open No. Hei 4-339806.

As mentioned above, the prior art relates to a method of producing final polymer particles of a desired size using the growth of coalescing polymer residues during the polymerization process by commercialized conventional suspension polymerization method. Various suspending stabilizers such as tricalcium phosphate, calcium carbonate, aluminum hydroxide, hydroxyethyl cellulose and polyvinyl alcohol are used in combination to suit the cleavage behavior. However, as the polymerization progresses in general, the particle size distribution of oil droplets is wider, and the particle size distribution of the final product is generally 0.5 to 1.2 mm in size of 90% or less. The amount of the suspension stabilizer used to suppress coalescence due to the increase in viscosity of oil residues is too high, which causes a problem of requiring an appropriate suspension stabilizer combination for commercial application.

That is, in the case of the cleavage and coalescence behavior of general polymer residues in the prior art, the monomer monomer added under vigorous stirring is separated into respective droplets in a dispersion medium such as water and proceeds in the form of bulk polymerization. These monomer sites collide in the system where agitation is performed, which causes the sites to coalesce and split. This collision proceeds with the unification and splitting of the ruins simultaneously at the early stage of the low viscosity polymerization, but in the middle or late stage of the high viscosity of the ruins, the coalescence caused by the collision is larger than the split, leading to the agglomeration of the ruins, which is impossible to remove the polymerization heat Until it occurs. The cleavage behavior of these growth-oriented polymer particles is suppressed by the suspension stabilizer during the polymerization process, and growth is inhibited, but growth continues until the end of the polymerization. Therefore, the conventional technology has a problem in that an excessive suspension stabilizer is required to produce the final polymer particles of a desired size, and thus the manufacturing cost is high, and the final particle size distribution is also relatively wide, resulting in a low production yield.

Suspension polymerization is most widely known as a method for producing commercially available expandable styrene resin particles using a combination of a fine solid powder and a highly viscous polymer as a suspension stabilizer. This method acts as a mechanism for adsorbing on the surface of oil droplets in the case of solid fine powders such as tricalcium phosphate and suppressing coalescence due to collision.In the case of highly viscous polymers, by increasing the viscosity of the continuous phase, the suspension stability effect is expressed. Since the viscosity of a dispersion medium becomes high and the removal time of a continuous liquid film is extended, coalescence is suppressed.

In contrast, in order to remedy the above-mentioned problems, the present inventors have formed a strong dispersant layer on the particle surface which prevents unity of particles during polymerization through a new suspension stabilizer combination, so that the cleavage and formation of the polymer remains is polymerized. This resulted in the cleavage and coalescence behavior of the new polymer remains that were initially completed, which resulted in very low amounts of suspension stabilizers used, resulting in high yields of final yields with excellent control of particle size distribution at low manufacturing costs. It has begun to develop a method for producing an expandable styrene resin having an excellent size distribution.

An object of the present invention is to provide a method for producing an expandable styrene resin having an excellent particle size distribution for obtaining at least 99% of an expandable styrene resin having a particle size of 0.5 to 1.2 mm by suspension polymerization.

Another object of the present invention is to use a new suspension stabilizer combination, and through the chemical action of each material constituting the suspension stabilizer combination, the cleavage and formation of polymer residues is completed at the beginning of the polymerization to provide an excellent styrene foam having excellent particle size distribution. It is to provide a manufacturing method.

Still another object of the present invention is to provide a method for producing a foamed styrene resin having excellent particle size distribution which has a cost reduction effect due to a small amount of suspension stabilizer during suspension polymerization.

The above and other objects of the present invention can be achieved by the following description. Hereinafter, with reference to the accompanying drawings will be described in detail the contents of the present invention.

Figure 1 shows the particle size distribution of the expandable styrene resin produced by the process of the present invention.

Magnesium phosphate (Mg (P ₂ O ₇ ) ₂ ) prepared by reacting magnesium chloride (MgCl ₂ ) and sodium phosphate (Na ₄ (P ₂ O ₇ ) ₂ ) during the polymerization during suspension polymerization of the styrene monomer Sodium polyacrylate, a water-soluble anionic interfacial adsorbent polymer, formaldehyde condensate of sodium alkylnaphthalene solfunate and an electrolyte material of sodium alkylnaphthalene sulfonate, a fat-soluble surfactant, were added. The present invention relates to a method for producing an expandable styrene resin having an excellent particle size distribution, characterized by obtaining 99% or more of particles having a size.

The method for producing an expandable styrene resin having excellent particle size distribution of the present invention includes using a new suspension stabilizer, which will be described in detail below.

The combination of the new suspension stabilizers is magnesium phosphate (Mg (P ₂ O ₇ ) ₂ ), sodium polyacrylate, which is a water-soluble anionic surfactant, and sodium alkylnaphthalene solfunate, an oil-soluble surfactant. ) Formaldehyde condensate and electrolyte material.

The magnesium phosphate (Mg (P ₂ O ₇ ) ₂ ) used in the production method of the present invention is the polymerization of magnesium chloride (MgCl ₂ ) and sodium phosphate (Na ₄ (P ₂ O ₇ ) ₂ ) during the polymerization It is obtained by the reaction and used in the form of solid fine powder.

2MgCl ₂ + Na ₄ (P ₂ O ₇ ) ₂ → 2Mg (P ₂ O ₇ ) ₂ )

Magnesium phosphate (Mg (P ₂ O ₇ ) ₂ ) prepared as described above is a very fine and uniform solid fine powder. It is an essential material for manufacturing.

In addition, sodium polyacrylate, the water-soluble anionic interfacial adsorbent polymer, is used after dissolving in a dispersion medium, and a formaldehyde condensate of Sodium Alkylnaphthalene solfunate is a monomer. It is used in addition to a styrene monomer. A feature of this technique is that the mixing effect by the chemical action of Miscelle is expressed by adding a water soluble anionic surfactant to the dispersion medium and adding a fat soluble surfactant to the organic phase. At this time, the interface of the relics is surface-activated to generate repulsion between the relics, and this effect does not occur between particles.

The electrolyte materials used in the present invention include nitrates, sulfates, carbonates and benzoates, among which benzoate is most preferred. Therefore, sodium benzoate (Na-benzoate) is used for such an electrolyte material, and it is preferable to use 0.10 to 0.50 parts by weight based on 100 parts by weight of styrene monomer. In the case of using 0.10 to 0.50 parts by weight of sodium benzoate, the surface activity of the polymer remains optimizes the mixing effect and the volume limiting effect by the polymer chain adsorbed at the interface, which is the electrolyte material. It is maintained until the polymerization is completed and forms a very stable suspension polymerization method in which the growth of particles does not occur even if the collision between the oil droplets is continuously performed. Thus, 99% or more of the expanded styrene resin particles having a particle size of 0.5 to 1.2 mm in the final product are obtained. It can be obtained in yield.

The present invention relates to a method for producing an expandable styrene resin having excellent particle size distribution by suspension polymerization of a styrene monomer, the styrene monomer having a styrene monomer or an acrylonitrile or α-methylstyrene mainly composed of styrene monomers. Mixture.

The expandable styrene resin particles having a particle size of 0.5 to 1.2 mm prepared according to the manufacturing method of the present invention are subjected to the processing of foaming and molding, and to agricultural and marine product packaging materials such as building insulation, apple boxes, fish boxes, TVs and VTRs. It is variously used as a packaging buffer for home appliances.

The invention can be better understood by the following examples, which are intended for the purpose of illustration of the invention and are not intended to limit the scope of protection defined by the appended claims.

Example

Example 1

10 kg of styrene monomer was added to the pre-dissolution tank 1, and 40 g of polyethylene wax was added thereto while stirring at 110 rpm. The temperature was raised to 70 ° C. and maintained for 60 minutes to dissolve the wax, which was then cooled to room temperature.

In pre-dissolution tank 2, 139 g of benzoyl peroxide and 50 g of t-butylperbenzoate are added to 30 kg of styrene monomer and dissolved for 30 minutes, and then a formaldehyde condensate of sodium soluble sodium alkylnaphthalene sulfonate is used. 1.2 g of sodium alkylnaphthalene solfunate) was added thereto, dissolved, and then dissolved in a solution prepared in pre-dissolution tank 1, followed by stirring for 30 minutes to prepare a dispersion.

Separately, add 40 kg of pure water in a 100 L pressure vessel, add 160 g of magnesium chloride, 240 g of sodium phosphate, 3 g of sodium acrylate, and 80 g of benzoate as a dispersant. After preparing the suspension was added to the dispersion prepared in pre-dissolution tank 2 and stirred at 110 rpm for 60 minutes. Thereafter, the polymerization was carried out until the polymerization rate reached 95% while maintaining the temperature of the reactor at 90 ° C.

Thereafter, the reactor was sealed and 3500 g of pentane was added at a rate of 1 g / min, while the temperature was raised to 110 ° C. When the addition was completed and the temperature reached 110 ℃ was maintained for 6 hours to the content of unreacted styrene monomer up to 3000 ppm or less.

In this case, the introduced blowing agent is impregnated into the glass transition polystyrene resin particles to be made into expandable styrene resin particles. After cooling to 45 ° C. or below, the residual blowing agent was vented. At this time, when the pressure of the reactor drops to normal pressure, it can be discharged to obtain expandable styrene resin particles in a slurry state.

The obtained polymer was separated from the water by dehydration, and then the water on the surface of the particle was removed to 0.3% or less through fluid bed drying, and then screened by particle size.

Based on the final results thus obtained, the effects of particle size adjustment for each suspension dispersion system were compared.

Comparative Example 1

Proceed in the same manner as in Example 1, but instead of adding 160 g of magnesium chloride and 240 g of sodium phosphate as a dispersant, 150 g of tricalcium phosphate was added to control particles of magnesium phosphate, which is a solid fine powder prepared of magnesium chloride and sodium phosphate, and Relative comparison of particle size distribution

Comparative Example 2

The same procedure as in Example 1 was carried out except that 1.2 g of a formaldehyde condensate of sodium alkylnaphthalene solfunate of sodium alkylnaphthalene sulfonate as an oil-soluble surfactant was not added.

Comparative Example 3

It carried out similarly to Example 1 except not adding 3.0 g of sodium polyacrylate which is a water-soluble surfactant.

Comparative Example 4

The suspension was prepared in the same manner as in Example 1 except that 150 g of tricalcium phosphate, 120 g of hydroxycellulose, and 30 g of polyvinyl alcohol were used as suspension stabilizers.

Comparative Example 5

The preparation was carried out in the same manner as in Example 1 except that 150 g of tricalcium phosphate, 240 g of hydroxycellulose, and 30 g of polyvinyl alcohol were used as suspension stabilizers.

Table 1 below shows the contents of each component used in Example 1 and Comparative Examples 1 to 5.

Component (parts by weight) Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Magnesium Chloride (MgCl ₂ ) 0.6500 0.6500 0.6500 - - Sodium Phosphate (Na ₄ (P ₂ O ₇ ) ₂ ) 0.6000 0.6000 0.6000 - - Water soluble surfactant 0.0075 0.0075 0.0075 - - - Fat-soluble surfactant 0.0030 0.0030 - 0.0030 - - Tricalcium phosphate 0.3750 - - 0.3750 0.3750 Benzoate (Na-benzoate) 0.2000 0.2000 0.2000 0.2000 - - Hydroxyethylcellulose - - 0.3000 0.6000 Polyvinyl alcohol - - 0.0750 0.0750

Table 2 below shows the particle size distribution of the expandable styrene resins prepared in Example 1 and Comparative Examples 1 to 5 and the yield of the final product having a particle size of 0.50 to 1.20 mm.

division Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Particle Size Distribution (%) 2.00 mm or more - 0.05 0.99 44.75 0.36 0.01 1.20 mm or more 0.01 0.78 4.26 51.08 3.65 0.42 1.10 mm or more 0.36 2.02 7.87 3.41 4.90 2.25 0.90 mm or more 18.05 20.37 14.59 0.76 15.26 13.54 0.70 mm or more 61.99 57.59 42.00 - 46.49 49.12 0.50 mm or more 20.28 17.63 20.17 - 19.12 26.31 0.30 mm or more 0.30 1.01 6.37 - 5.75 6.03 pass 0.01 0.5 3.75 - 4.47 2.32 Yield (%) between 0.50 and 1.20 mm 99.68 97.61 84.63 4.17 85.77 91.22

As can be seen in Example 1 and Comparative Examples 1 to 5 of Table 2 above, as a result of the preferred combination of the suspension stabilizers according to the present invention, 99% or more of an expandable styrene resin having a particle size of 0.5 to 1.2 mm was obtained. .

The method for producing an expanded styrene resin having excellent particle size distribution according to the present invention utilizes a new suspension stabilizer combination, and through the chemical action of each material constituting the suspension stabilizer combination, cleavage and formation of polymer droplets are completed at the beginning of the polymerization. Excellent particle size distribution, less suspension stabilizer requirements during suspension polymerization, has a cost-effective effect.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (4)

In suspension polymerization of styrene monomer, magnesium phosphate (Mg (P ₂ O ₇ ) ₂ ), water-soluble anion, prepared by reacting magnesium chloride (MgCl ₂ ) and sodium phosphate (Na ₄ (P ₂ O ₇ ) ₂ ) during polymerization 0.5 to 1.2 mm in size, by adding sodium polyacrylate as an interfacial adsorptive polymer, formaldehyde condensate of sodium alkylnaphthalene solfunate as an oil-soluble surfactant, and an electrolyte material A method for producing an expandable styrene resin having excellent particle size distribution, characterized in that 99% or more of particles are obtained. The method of claim 1, wherein the electrolyte material is selected from the group consisting of nitrates, sulfates, carbonates, and benzoates. The method of claim 1, wherein the benzoate is used in an amount of 0.10 to 0.50 parts by weight based on 100 parts by weight of the styrene monomer. The method according to claim 1, wherein the styrene monomer is a styrene monomer or a mixture with acrylonitrile or α-methylstyrene mainly composed of styrene monomers.