KR20160056126A - Method for producing expandable polystyrene small beads with large seed particles - Google Patents

Abstract

The present invention relates to a method for producing small expandable polystyrene beads using large seed particles. More specifically, the method comprises the steps of: (1) preparing an aqueous dispersion which selectively contains large polystyrene-type seed particles, a dispersant, and a surfactant; (2) adding thereto a styrene-type monomer in which an initiator and a chain transfer agent are dissolved, to expand the large seed particles; (3) performing polymerization of the monomer while splitting the large seed particle into two or more small particles; and (4) adding a blowing agent thereto, to obtain a spherical particle smaller than the large seed particle. The method for producing small expandable polystyrene beads further utilizes a chain transfer agent in addition to the conventional seed polymerization methods, thereby splitting the large seed particle into smaller ones while controlling the speed of polymerization in the polymerization step to successfully provide a novel method for producing a bead which is smaller than a seed particle.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for producing expandable polystyrene small particles,

The present invention relates to a method for producing expandable polystyrene fine particles using an allergen seed. More particularly, the present invention relates to a method for producing expandable polystyrene fine particles which is characterized by obtaining spherical small particles smaller than raw seed particles.

As a method for producing expandable polystyrene particles, a suspension polymerization method, an extrusion method and a seed polymerization method are widely known.

The suspension polymerization method is a method of producing polymer particles by using water as a dispersion medium and using water-insoluble monomers in the presence of a dispersion stabilizer such as a dispersant or a surfactant. However, since this polymerization is performed by dispersing the monomers present in the aqueous phase by mechanical force, the obtained polymer particles have a very wide distribution of 0.1 to 1000 mu m in size, and thus the generation of non-ionic grades and outbreaks , Which requires a stepwise fractionation operation through a separator to obtain a genuine product. In order to overcome such disadvantages, Korean Unexamined Patent Application Publication No. 1993-0010062 and Korean Unexamined Patent Publication No. 2000-0008971 disclose a method for producing expandable polystyrene particles having a narrow particle size distribution.

Korean Unexamined Patent Publication No. 2005-0024330 discloses another method of producing expandable polystyrene particles by an extrusion method so as to have a uniform particle size according to the hole size of a die. However, in the process where polystyrene contains a blowing agent, it is necessary to control the dispersion and generation heat of the melt, which may lead to problems such as a decrease in molecular weight upon extrusion, degradation of additives, and deterioration in quality including foaming of the final product. In order to overcome such a problem, Korean Patent No. 703828 and Korean Patent No. 801275 disclose a method of impregnating a blowing agent in a separate reactor after extruding polystyrene or impregnating extruded pellets simultaneously with seed polymerization.

As another method, Korean Patent Publication No. 2002-0000556 and Korean Patent Publication No. 2003-0070951 disclose a seed polymerization method. In the seed polymerization method, a bead having a narrow particle size distribution is fractionated by fractionation of beads obtained by the suspension polymerization method, or pellets or particles of a uniform cylindrical pellet are extruded into a suspension using a seed, and the monomer is gradually added It is the process of obtaining seed particles of desired size by growing the seed size. However, such a seed polymerization method has a complicated manufacturing process in two steps, and since it is a polymerization method in which seeds of the fine particles are grown as major particles, particles smaller than the seed can not be obtained.

Korean Patent Registration No. 11099028 discloses a method for producing expandable polystyrene beads using an allergen seed. However, this method regulates the amount of monomers injected in the swelling step to induce sub-fraction due to over swelling of the allergic seed, And the amount of the monomer to be added is the same or larger than the amount of the seed.

It is an object of the present invention to provide an efficient new method for producing expandable polystyrene beads smaller than the seed.

It is still another object of the present invention to provide a novel method for producing expandable polystyrene fine particles which has the same swelling step as the conventional seed polymerization method and has no limitation on the amount of monomers to be added relative to the seed amount.

In the present invention, unlike the conventional seed polymerization method in which fine particles are grown as major particles, a chain transfer agent is introduced to control the polymerization rate in the polymerization step, and a step of subdividing the allergen seed is introduced to produce a novel small- ≪ / RTI >

The method for producing expandable polystyrene beads using the allergen seed according to the present invention enables efficient production of expandable polystyrene beads smaller than the seed. The present invention also shows the effect of enabling the production of expandable polystyrene beads having the same seed swelling step and swelling step as the conventional seed swelling method and having no limitation on the amount of monomers to be added relative to the seed amount.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a temperature step and a main step of a method for producing expandable polystyrene fine particles using an allergen seed according to an embodiment of the present invention. FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments and comparative examples of the present invention will be described in detail with reference to the accompanying drawings. It is to be understood that the same is by way of illustration and example only and is not to be construed as limiting the present invention But does not mean that the technical idea and scope of the present invention are limited.

The present invention relates to a method for producing expandable polystyrene fine particles using an allergen seed. More particularly, the present invention relates to a method for producing an aqueous dispersion comprising the steps of: (1) forming an aqueous dispersion comprising a polystyrene-based opponent seed, a dispersant, and a surfactant; (2) adding an initiator and a styrene- (3) dividing the major particle seed into two or more minor particles while performing the polymerization of the monomers, and (4) introducing a foaming agent to obtain small spherical particles smaller than the major particle seed.

In the practice of the present invention, (1) in the step of forming an aqueous dispersion optionally comprising a polystyrene major particle seed, a dispersant, and a surfactant, the major particle seed may be selected from the group consisting of conventional cylindrical pellets, spherical beads, .

The above-mentioned allergic seeds can be produced by selectively introducing various additives such as graphite, carbon black, carbon nanotubes, and flame retardants, or by using functional resin seeds such as high impact and high heat resistance to provide a wide variety of heat insulation performance, antistatic ability, Functionality can be given.

The dispersing agent may be prepared by using any dispersing agent commonly used in conventional expandable polystyrene polymerization. Examples thereof include inorganic dispersing agents; Tricalcium phosphate, magnesium pyrophosphate, organic dispersant; Polyvinyl alcohol, methylcellulose, polyvinylpyrrolidone, and the like. In the present invention, 0.3 to 1.0 part by weight of tricalcium phosphate is used relative to 100 parts by weight of the expandable polystyrene fine particles.

       As the surfactant, sodium laurylsulfonate, sodium alkylbenzenesulfonate, sodium oleylsulfonate and the like are used. In the present invention, 0.01 to 0.2 parts by weight of sodium alkylbenzenesulfonate is used relative to 100 parts by weight of expandable polystyrene fine particles.

In the practice of the present invention, in the step of swelling allele seeds by adding a styrenic monomer having dissolved therein an initiator and a chain extender, two types of initiators having different initiation temperatures were used as the initiator. In general, in the expandable polystyrene polymerization In the practice of the present invention, two kinds of initiators such as benzoyl peroxide (BPO) and t-butyl peroxybenzoate (TBPB) may be added in an amount of 0.1 to 100 parts by weight based on 100 parts by weight of the styrene- 0.5 part by weight.

The chain transfer agent is generally used for controlling the molecular weight upon radical chain polymerization, and mercaptans having a high transfer constant when polymerizing styrene monomer can be used. In the practice of the present invention, t-dodecylmercaptan TDM) is used in an amount of 0.01 to 0.5 parts by weight, preferably 0.1 to 0.2 parts by weight, based on 100 parts by weight of the styrene-based monomer. If the chain transfer agent is used in an amount of 0.01 part by weight or less, the effect of particle subdivision is small. If the chain transfer agent is used in an amount of 0.5 part by weight or more, the molecular weight is excessively lowered.

In the practice of the present invention, an additive that imparts various properties of the polymer can be added. Specifically, a flame retardant, a solvent, a bubble regulator, and the like can be used.

In the practice of the present invention, in the step of adding a foaming agent to obtain a spherical small particle smaller than an allergic seed, the foaming agent may be blowing agents C4 to C6 used for producing general expandable polystyrene, for example, butane, i- Butane, n-pentane, i-pentane, neo-pentane, cyclopentane and halogenated hydrocarbons. The foaming agent preferred in the present invention is n-pentane or i- 15 parts by weight.

In the practice of the present invention, a method for producing expandable polystyrene fine particles using an allele seed is as follows.

Ultrapure water, major particle seed, dispersant, and surfactant are fed into the reactor to maintain dispersion. When this process is completed, the temperature of the reactor is maintained between 60 DEG C and 80 DEG C, and a certain amount of the styrene monomer is slowly added thereto for 2 hours with the initiator and chain transfer agent to swell the allele seed. Thereafter, the inlet of the reactor is closed, and the temperature is raised to 100 to 130 ° C for 2 to 5 hours, and the remaining styrene monomer is added to proceed the polymerization. At this time, the particles are subdivided by the side glass of the reactor Can be confirmed. Subsequently, a blowing agent is added and kept at a temperature of 100 ° C to 130 ° C for 3 to 6 hours to prepare expandable polystyrene fine particles.

In the present invention, the expandable polystyrene beads are prepared by the steps of: (1) forming an aqueous dispersion optionally containing a polystyrene-based opponent seed, a dispersant and a surfactant; (2) adding an initiator, a styrene- (3) separating the major particle seed into two or more minor particles while polymerizing the monomer, and (4) injecting a foaming agent to obtain a spherical minor particle smaller than the major particle seed . The foaming and forming of the obtained expandable polystyrene fine particles may be carried out under usual foaming and molding conditions, and there is no particular limitation.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples.

≪ Example 1 >

(Preparation of Expandable Polystyrene Small Particles) (100 parts by weight of expandable polystyrene fine particles were prepared from 50 parts by weight of an allergic seed and 50 parts by weight of a styrene monomer)

Polystyrene pellets (GP 150K) having a length of 2 to 3 mm and a width of 1 to 2 mm were used as the styrene-based resin allele seeds. 0.2 kg of a dispersant (tricalcium phosphate; Duvorn oil) and 0.04 g of a surfactant (alkylbenzene sulfonate; LGH Health) were added to 40 kg of ultrapure water in a 100 L reactor, and 20 kg of the resin particle seed was added thereto. Thereafter, the reactor temperature was raised to 60 DEG C, and 0.05 kg of a low-temperature initiator (benzoyl peroxide; Hansol Chemical Co., Ltd.), 0.03 of a high-temperature initiator (t-butyl peroxybenzone; kg, and 0.1 kg of a chain transfer agent (t-dodecylmercaptan, diisocyanate) were dissolved and then charged for 2 hours. Subsequently, the reactor inlet was closed, and 15 kg of the styrene monomer was slowly added thereto while heating the temperature from 60 ° C to 125 ° C for 3.5 hours to proceed the polymerization. After this was completed, 3 kg of blowing agent (pentane; SK) was introduced into the reactor at a pressure of nitrogen at 125 DEG C and the impregnation was carried out for 5 hours while maintaining the final reactor pressure at 13 kgf / cm < 2 >. Thereafter, the mixture was cooled to 30 DEG C or lower and the product was discharged to the reactor. The product was washed, dried, and size and distribution were measured.

≪ Example 2 >

(100 parts by weight of expandable polystyrene fine particles were prepared from 50 parts by weight of an opaque seed having graphite introduced therein and 50 parts by weight of a styrene monomer)

10 kg of graphite (HCN-905) was added to 100 kg of polystyrene (Kumho Petrochemical GP 150), and the mixture was melted at 230 ° C in a twin-screw extruder, and underwater cutting To obtain uniform resin particles containing graphite having an average diameter of 1.2 mm. 0.2 kg of a dispersant (tricalcium phosphate; Duvorn oil) and 0.04 g of a surfactant (alkylbenzenesulfonate; LG Household Health) were added to 40 kg of ultrapure water in a 100 L reactor, and 20 kg of the resin particle seed was added. Thereafter, the reactor was heated to 60 DEG C, and 0.05 kg of a low temperature initiator (benzoyl peroxide; Hansol Chemical) and 0.03 kg of a high temperature initiator (t-butyl peroxy benzoate; Hosung Chemex) were added to 5 kg of a styrene monomer , 0.02 kg of a chain transfer agent (t-dodecylmercaptan, isomerization) were dissolved and the mixture was added for 2 hours. Subsequently, the reactor inlet was closed, and 15 kg of the styrene monomer was slowly added thereto while heating the temperature from 60 ° C to 125 ° C for 3.5 hours to proceed the polymerization. After this was completed, 3 kg of blowing agent (pentane; SK) was introduced into the reactor at a pressure of nitrogen at 125 ° C. and impregnation was carried out for 5 hours while maintaining the final reactor pressure at 13 kgf / cm 2. Thereafter, the mixture was cooled to 30 DEG C or lower and the product was discharged to the reactor. The product was washed, dried, and size and distribution were measured.

≪ Example 3 >

(100 parts by weight of expandable polystyrene fine particles were prepared from 60 parts by weight of an opaque seed in which graphite was introduced and 40 parts by weight of a styrene monomer)

10 kg of graphite (HCN-905) was added to 100 kg of polystyrene (Kumho Petrochemical GP 150), and the mixture was melted at 230 ° C in a twin-screw extruder, and underwater cutting To obtain uniform resin particles containing graphite having an average diameter of 1.2 mm. 0.2 kg of a dispersant (tricalcium phosphate; Duvorn oil emulsion) and 0.04 g of a surfactant (alkylbenzenesulfonate; LGH Health) were added to 40 kg of ultrapure water in a 100 L reactor, and 24 kg of the resin particle seed was added thereto. Thereafter, the temperature of the reactor was raised to 60 DEG C, 0.04 kg of a low-temperature initiator (benzoyl peroxide; Hansol Chemical), 0.02 kg of a high-temperature initiator (t-butyl peroxybenzone; kg, and 0.02 kg of a chain transfer agent (t-dodecylmercaptan, isomerization) were added and the mixture was added for 2 hours. Subsequently, the inlet of the reactor was closed, and 11 kg of the styrene monomer was slowly added thereto while heating the temperature from 60 ° C to 125 ° C for 3.5 hours to proceed the polymerization. After this was completed, 3 kg of blowing agent (pentane; SK) was introduced into the reactor at a pressure of nitrogen at 125 DEG C and the impregnation was carried out for 5 hours while maintaining the final reactor pressure at 13 kgf / cm < 2 >. Thereafter, the mixture was cooled to 30 DEG C or lower and the product was discharged to the reactor. The product was washed, dried, and size and distribution were measured.

≪ Comparative Example 1 &

(Preparation of Expandable Polystyrene Particles by Seed Polymerization (100 parts by weight of expandable polystyrene particles were prepared from 50 parts by weight of graphite-introduced seed and 50 parts by weight of styrene monomer)

10 kg of graphite (HCN-905) was added to 100 kg of polystyrene (Kumho Petrochemical GP 150), and the mixture was melted at 230 ° C in a twin-screw extruder, and underwater cutting To obtain uniform resin particles containing graphite having an average diameter of 1.2 mm. 0.2 kg of a dispersant (tricalcium phosphate; Duvorn oil) and 0.04 g of a surfactant (alkylbenzenesulfonate; LG Household Health) were added to 40 kg of ultrapure water in a 100 L reactor, and 20 kg of the resin particle seed was added. Thereafter, the reactor temperature was raised to 60 DEG C, and 0.05 kg of a low-temperature initiator (benzoyl peroxide; Hansol Chemical Co., Ltd.), 0.03 of a high temperature initiator (t-butyl peroxybenzone; kg was dissolved and added for 2 hours. Subsequently, the reactor inlet was closed, and 15 kg of the styrene monomer was slowly added thereto while heating the temperature from 60 ° C to 125 ° C for 3.5 hours to proceed the polymerization. After this was completed, 3 kg of blowing agent (pentane; SK) was introduced into the reactor at a pressure of nitrogen at 125 ° C. and impregnation was carried out for 5 hours while maintaining the final reactor pressure at 13 kgf / cm 2. Thereafter, the mixture was cooled to 30 DEG C or lower and the product was discharged to the reactor. The product was washed, dried, and size and distribution were measured.

Property table Item Example 1 Example 2 Example 3 Comparative Example 1
Particle size (mm) and particle size distribution (%)
1.7mm or more - - - 2.9% 1.4 to 1.7 mm 0.4% 0.3% 0.1% 91.3% 1.2 to 1.4 mm 32.9% 6.4% 8.4% 5.8% 1.0 to 1.2 mm 39.5% 27.9% 60.2% 0.8 to 1.0 mm 23.4% 56.4% 23.9% 0.6 to 0.8 mm 1.7% 3.7% 2.9% 0.4 to 0.6 mm 1.5% 3.1% 2.5% 0.4 mm or less 0.6% 2.2% 2.0%

The method for evaluating the particle size and the distribution in the above Table 1 was specifically carried out as follows.

1) Particle size distribution: Measurement of the content after vibration for 5 minutes using a shaker equipped with a standard body

From the results shown in the above Table 1, it was possible to obtain the expandable polystyrene beads smaller than the seed even though the seeds of the same size to the same size or larger were used as compared with the existing seed polymerization of the < Comparative Example 1 >. Further, in Example 2 and Example 3, graphite was introduced into the alligator seed for the purpose of improving the heat insulating performance of the final product, whereby the expandable polystyrene beads having uniformly distributed graphite in the particle could be obtained, >, But relatively small expandable polystyrene beads could be obtained. Particularly, in Example 3, it was confirmed that the particles were subdivided in the polymerization step by using the chain transfer agent even though the amount of the seed was larger than that of the styrene monomer and the seed swelling was small.

Claims (6)

(1) forming an aqueous dispersion containing a polystyrene-based opponent seed, a dispersant, and a surfactant; (2) swelling the allergic seed by adding a styrene-based monomer dissolved in the initiator and the chain transfer agent; Separating the major particle seed into two or more minor particles while polymerizing the monomer, and (4) introducing a foaming agent to obtain a spherical minor particle smaller than the major particle seed.
The method of claim 1, wherein the alligator seed comprises an additive selected from the group consisting of graphite, carbon black, carbon nanotubes, and flame retardants.
The method according to claim 1, wherein the all major seed is a high-impact or high-heat-resistant functional resin seed.
The method according to claim 1, wherein the weight ratio of the allergic seed and the styrenic monomer is 10-90: 90-10.
The method according to claim 1, wherein the impregnation is carried out by introducing a foaming agent, and the foaming agent is used in an amount of 4 to 15 parts by weight based on 100 parts by weight of the expandable polystyrene fine particles.
The method according to claim 1, wherein the swelling step (2) proceeds at 60 ° C to 80 ° C, and the polymerization step (3) proceeds at 100 to 130 ° C.

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