KR20130071864A - Manufacturing method of expandable polystyrene particles - Google Patents

Abstract

PURPOSE: A manufacturing method of a polystyrene foam is provided to provide a polystyrene foam without loss of foam performance, heat resistance, and fusing, by introducing an excess of brome-based flame retardant when polymerizing polystyrene foam particles. CONSTITUTION: A manufacturing method of a polystyrene foam comprises a step of manufacturing a seed with a pellet or polystyrene particle containing graphite; a step of conduct polymerization of the seed in an aqueous phase, along with an excess of a brome-based flame retardant. The oxygen index of the polystyrene foam is 35%. The use amount of the brome-based flame retardant is 2-20 parts by weight. The size of the graphite is 1-50 micron.

Description

Manufacturing method of expandable polystyrene particles

The present invention relates to a process for producing expandable polystyrene particles for providing a polystyrene foam having an oxygen index of at least 35%. Expandable polystyrene particles to provide polystyrene foam having an oxygen index of 35% or more are prepared from polystyrene particles or pellets containing graphite, and the seed is polymerized in an aqueous phase with an excess of bromine-based flame retardant, and at the same time a blowing agent is introduced. It is done through the steps.

Expanded polystyrene is widely used as a building material due to its excellent heat insulation performance and easy construction, but has a disadvantage in that flame retardancy is lowered than that of inorganic insulation such as fiberglass or gypsum board.

In general, flame retardants used in polystyrene foams are treated with hexabromocyclododecane (HBCD) as the best material because of its high bromine content and excellent flame retardancy and high thermal stability.

Specifically, 0.5 to 1 part by weight of hexabromocyclododecane is used as a cell control agent for improving flame retardancy and controlling bubble size when preparing expandable polystyrene particles, based on expandable polystyrene particles. Polystyrene foam, which is provided by foaming and molding polystyrene particles, has an oxygen index of 26% flame retardancy.

Korean Patent Laid-Open Publication No. 2000-0003097 provides a foamed styrene polymer resin bead having a uniform cell structure by adding a bromine-based flame retardant at an appropriate time during the polymerization reaction, and improving the fusion state, surface shrinkage, heat resistance and strength. The flame retardant is added to 0.05 to 1.0% by weight, and if the amount is less than 0.05% by weight, the flame retardant effect is reduced, and when the content exceeds 1.0% by weight, the heat resistance and other physical properties of the resin beads are mentioned. have.

As such, such a bromine-based flame retardant interferes with particle formation during suspension polymerization, and acts as a factor that inhibits physical properties including bubble size, thereby increasing the amount of introduction.

Accordingly, it is an object of the present invention to provide a novel method for producing expandable polystyrene particles for providing polystyrene foam having an oxygen index of 35% or more by introducing an excessive amount of bromine flame retardant when polymerizing expandable polystyrene particles.

Another object of the present invention is to provide a novel method for producing expandable polystyrene particles to provide a polystyrene foam having no physical deterioration such as foamability, heat resistance and fusion, even when an excessive amount of bromine-based flame retardant is introduced during polymerization of the expandable polystyrene particles.

In the present invention, polystyrene particles or pellets containing graphite are prepared, and foamed polystyrene particles are prepared to provide a polystyrene foam having an oxygen index of 35% or more by polymerizing the seeds in an aqueous phase with an excess of bromine-based flame retardant. It was.

Unlike the general suspension polymerization, the production method of the present invention has no difficulty in forming the particles, the final foamable polystyrene particles including foamability and molecular weight of 300,000 or more, there was no degradation in heat resistance, it was confirmed that the fusion and appearance quality is excellent.

The present invention relates to a process for producing expandable polystyrene particles for providing a polystyrene foam having an oxygen index of at least 35%. Expandable polystyrene particles to provide polystyrene foam having an oxygen index of 35% or more are prepared from polystyrene particles or pellets containing graphite, and the seed is polymerized in an aqueous phase with an excess of bromine-based flame retardant, and at the same time a blowing agent is introduced. It is done through the steps.

In the practice of the present invention, the seed in the form of polystyrene particles or pellets containing graphite may be prepared by an extrusion method using conventional suspension polymerization or underwater cutting.

In the practice of the present invention, the graphite contained in the seed in the form of polystyrene particles or pellets may use natural graphite or synthetic graphite, and the particle size is preferably 1 to 50 microns, particularly preferably 2 to 10 microns. In the present invention, the content of graphite is preferably used 0.05 to 20 parts by weight, more preferably 0.5 to 10 parts by weight based on the expandable polystyrene particles.

In the practice of the present invention, the bromine flame retardant is hexabromocyclododecane, pentabromomonochlorocyclohexane, pentabromophenyl allyl ether, tetrabromocyclooctane, tetrabromo vinylcyclohexane, 2,2 ' Bromine type flame retardants, such as-(4-allyloxy-3,5-dibromophenyl) propane and tribromophenyl allyl ether, can be used, Preferably it is hexabromo cyclododecane. The content of the flame retardant may be 2 to 20 parts by weight based on the expandable polystyrene particles, preferably 3 to 10 parts by weight, when the content of the flame retardant is less than 2 parts by weight, it is difficult to secure an oxygen index of at least 35%, 20 If more than parts by weight, economical efficiency is low.

In the practice of the present invention, the blowing agent is a conventional blowing agent used for the expandable polystyrene particles, and suitable blowing agents may be aliphatic hydrocarbons having 4 to 6 carbon atoms, preferably butane and pentane. The content of the blowing agent may be 3 to 10 parts by weight based on the expandable polystyrene particles, preferably 5 to 8 parts by weight.

In the practice of the invention, conventional suspension stabilizers, peroxide initiators, foaming aids, flame retardant aids and nucleating agents may be added in suspension polymerization.

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

<Example 1> using a graphite-containing oxide, and 3 parts by weight of a flame retardant based on the introduction of the expandable polystyrene particles Width

40 kg of water, 0.2 kg of sodium pyrophosphate (Youngjin Industrial Co., Ltd.) and 0.5 kg of magnesium chloride (CMC, 30% aqueous solution) were added to a 100L reactor, followed by stirring and pellet-containing seeds (Kumho Petrochemical; MP20G). 20 kg was added. After that, the reactor temperature was raised to 70 ° C, 1.3 kg of flame retardant (hexabromocyclododecane; GLC; CD75P ^TM ) and 5 kg of low-temperature initiator (benzoyl peroxide; Hansol Chemical) in 5 kg of styrene monomer (Styrene Monomer; SK) , 0.03 kg of high temperature reagent (t-butyl peroxy benzoneate; Hosung Chemex) was dissolved and added for 2 hours. After the reactor inlet was closed and 15 kg of styrene monomer was slowly added while heating the temperature from 70 ° C. to 115 ° C. for 3.5 hours to proceed with polymerization. After this was completed, 3 kg of blowing agent (pentane; SK) was introduced into the reactor at 115 ° C. under nitrogen pressure, and impregnation was performed for 5 hours while maintaining the final reactor pressure of 13 kgf / cm ² . After cooling below 30 ℃ and the product was discharged to the reactor. The product was washed with water, dried, and applied to a blending agent used for preparing conventional expandable polystyrene particles, and subjected to foaming, molding, and physical property evaluation. The results are shown in Table 1.

< Example 2 > 7 parts by weight of flame retardant introduced based on expandable polystyrene particles using graphite-containing seeds

Example 1 was repeated in the same manner except using 3 kg of flame retardant.

< Comparative Example 1 > 1 part by weight of flame retardant introduced on the basis of expandable polystyrene particles using a general suspension polymerization method

40 kg of water and 0.2 kg of tricalcium phosphate (Dubon emulsification) were added to a 100L reactor and stirred, and 0.4 kg of a flame retardant (hexabromocyclododecane; GLC; CD75P ^TM ) was added to 40 kg of styrene monomer (SK). 0.14 kg of (benzoyl peroxide; Hansol Chemical) and 0.06 kg of a high temperature initiator (t-butyl peroxy benzoate; Hosung Chemicals) were dissolved and added. Then, the temperature was raised to 90 ° C. and maintained for 6.5 hours. After the inlet of the reactor was closed, the temperature was slowly increased from 90 ° C. to 115 ° C. for 1 hour and 30 minutes. At 115 ° C., 3 kg of blowing agent (pentane; SK) was added to the reactor under nitrogen pressure, and the final reactor pressure was 13 kgf / cm ² . Impregnation was performed for 5 hours while maintaining. After cooling below 30 ℃ and the product was discharged to the reactor. The product was washed with water, dried, and applied to a blending agent used for preparing conventional expandable polystyrene particles, and subjected to foaming, molding, and physical property evaluation. The results are shown in Table 1.

< Comparative Example 2 > 3 parts by weight of flame retardant introduced on the basis of expandable polystyrene particles using a general suspension polymerization method

Comparative Example 1 was repeated in the same manner except that 1.3 kg of flame retardant was used.

< Comparative Example 3 > 7 parts by weight of flame retardant introduced on the basis of expandable polystyrene particles using a general suspension polymerization method

Comparative Example 1 was repeated in the same manner except using 3 kg of flame retardant.

< Comparative Example 4 > A product in which 3 parts by weight of a flame retardant is introduced on the basis of expandable polystyrene particles using a general suspension polymerization method, and a low temperature initiator is adjusted to increase the molecular weight.

Comparative Example 1 was repeated in the same manner except that 1.3 kg of flame retardant was used and 0.09 kg of low temperature initiator.

Property Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Graphite content
(weight%) 4 4 - - - - Flame retardant dosage
(Parts by weight) 3 7 One 3 7 3 Molecular weight (only) 35 34 26 24 During polymerization
particle
Unformed 30 Effervescent (pear) 65 65 65 60 35 Appearance quality Good Good Good Shrink Good Fusion (%) 70 or more 70 or more 70 or more 30 70 or more Oxygen Index (%) 36 40 26 34 33

In Table 1, the graphite content, flame retardant injection amount, molecular weight, foamability, fusion and oxygen index were carried out specifically as follows.

1) Graphite content: dissolved in THF (tetrahydrofuran) solvent and filtered (wet method)

2) Flame retardant dosage: Calculate the dosage based on the expandable polystyrene particles

3) Molecular weight: measured by GPC (Gel Permeation Chromatography)

4) Foamability: Foamed drainage when foamed for 5 minutes at 0.3K steam pressure

5) Fusion: It shows the state in which the foamed granules of the molded products are in close contact with each other, and the percentage of the breakage of the foamed granules among the fractured surfaces of the molded product (%)

6) Oxygen index: measured by standard method of KS M ISO 4589-2: 2006

From the results of Table 1, when polymerizing in an aqueous phase with an excessive flame retardant using a polystyrene seed containing graphite, it is not disturbed by particle formation due to dispersion instability, without deterioration in appearance quality and fusion due to foamability, heat resistance degradation Oxygen index was able to secure excellent flame resistance of more than 35%.

Looking at the comparative examples, using a typical suspension polymerization, when introducing 1 part by weight of the flame retardant based on the expandable polystyrene particles, the oxygen index is lowered, when 3 parts by weight of the flame retardant is introduced when the bubble size (Cell Size) is too fine As a result, the appearance of the molded product was constricted, the fusion was lowered, and when 7 parts by weight of the flame retardant was introduced, particles were not formed due to dispersion instability. In addition, when 3 parts by weight of the flame retardant was introduced as in Comparative Example 4, and the molecular weight was increased to improve the heat resistance, the appearance shrinkage and fusion of the molded article were improved, but the foamability due to the high molecular weight was reduced.

As a result, the introduction of graphite, seed polymerization, and excessive introduction of flame retardant did not lead to dispersion instability, deterioration in appearance quality and fusion caused by deterioration of heat resistance, and surprisingly, the molecular weight was about 350,000, but there was no deterioration in foamability.

Although the present invention has been described in detail in the above embodiments, the above embodiments are not described to limit the scope of the present invention, but are described for illustrative purposes only.

Those skilled in the art will recognize that modifications of the invention are possible without departing from the scope and spirit of the invention, and the scope of the invention is determined by the claims that follow.

Claims (5)

A method of producing expandable polystyrene particles comprising preparing a seed in the form of polystyrene particles or pellets containing graphite, polymerizing the seed with an excess of a brominated flame retardant in an aqueous phase, and introducing a blowing agent.       The method according to claim 1, wherein the oxygen index of the polystyrene foam made of the expandable polystyrene particles is 35% or more.       The method of claim 1, wherein the brominated flame retardant is used in an amount of 2 to 20 parts by weight based on 100 parts by weight of the expandable polystyrene particles.       The method of claim 1, wherein the size of the graphite is 1 to 50 microns. The method of claim 4, wherein the graphite is 0.05 to 25 parts by weight based on 100 parts by weight of expandable polystyrene particles.