KR20110065707A - Expandable polystyrene bead comprising silicone and expanded vermiculite, and method for preparing the same - Google Patents

Abstract

PURPOSE: Expandable polystyrene beads are provided to ensure excellent fire retardant characteristic while preventing the deterioration of a foaming property. CONSTITUTION: Expandable polystyrene beads are such that a flame retardant is dispersed within a styrene polymer, wherein the flame retardant comprises a silicon-based powder and an expandable vermiculite powder. A method for preparing the expandable polystyrene beads comprises the steps of: dispersing a flame retardant including the silicon-based powder and the expandable vermiculite powder into the styrene polymer particles; and mixing a blowing agent within the styrene polymer particles.

Description

Expandable polystyrene beads containing silicon and expanded vermiculite and a method for manufacturing the same {EXPANDABLE POLYSTYRENE BEAD COMPRISING SILICONE AND EXPANDED VERMICULITE, AND METHOD FOR PREPARING THE SAME}

The present invention relates to flame retardant expandable polystyrene beads and a method for producing the same.

Polystyrene foam moldings can be obtained by foaming and molding expandable polystyrene beads, and they are widely used as building materials due to their excellent heat insulating properties.

By the way, the polystyrene foam molded article has a disadvantage of being excellent in heat insulation and workability, but poor in flame retardancy, and thus has been difficult to be widely used as a building material.

Thus, various efforts have been made to improve the flame retardancy of polystyrene foam moldings, one of which has been to provide expandable polystyrene beads containing a flame retardant.

Conventionally, halogen-based flame retardants, phosphorus-based flame retardants, expanded graphite powders and the like have been mainly used as flame retardants contained in expandable polystyrene beads.

For example, U. S. Patent No. 6,444, 714 describes a method for producing expandable styrene polymer bead-type particles by polymerizing styrene in a suspension solution, optionally with at least one comonomer. Carrying out the polymerization in the presence of from about 50% by weight of "expanded graphite" and from 2 to 20% of a phosphorus-based flame retardant, and at least one aliphatic hydrocarbon blowing agent having from 4 to 6 carbon atoms prior to the polymerization. A method of providing expandable styrene bead-shaped particles is disclosed which includes adding to, during, or after, and wherein the average diameter is from 0.2 to 2.0 mm.

U. S. Patent No. 6,444, 714 also discloses polymers of styrene and optionally at least one comonomer; 5 to 50% by weight of expanded graphite as a uniformly dispersed flame retardant; And at least one aliphatic hydrocarbon blowing agent having 4 to 6 carbon atoms; wherein the expanded graphite has an average particle size of 20 to 100 μm, and the styrene polymer particles are 0.2 to 2.0 mm A foamable styrene polymer particle powder having an average diameter of is disclosed.

As described above, the conventional flame retardant foamable polystyrene beads mainly used a flame retardant material such as halogen flame retardant, phosphorus flame retardant, expanded graphite powder, vermiculite powder and the like.

However, halogen-based flame retardants have a tendency to be limited by environmental regulations.

In addition, the phosphorus-based flame retardant, expanded graphite powder, vermiculite powder, etc. may cause a problem that the growth of the foaming cell is inhibited during foaming as the amount of the flame-retardant, expanded graphite powder, vermiculite powder, etc. is increased.

As described above, it is not easy to find an effective flame retardant that does not inhibit physical properties such as foamability of the foamed polystyrene beads and allows the foamed polystyrene beads to exhibit excellent flame retardancy.

Accordingly, the present invention is to provide a foamed polystyrene bead and a method for producing the polystyrene foam molded article exhibiting improved flame retardancy and excellent thermal insulation by dispersing and mixing the silicon-based powder and expanded vermiculite powder in a styrene polymer.

The present invention has been made to solve the above problems of the prior art,

In the expandable polystyrene beads in which the flame retardant is dispersed in the styrene-based polymer, the flame retardant includes the silicon-based powder and the expanded vermiculite powder.

Further comprising dispersing a flame retardant comprising silicon-based powder and expanded vermiculite powder in the styrene polymer particles, and incorporating a blowing agent in the styrene polymer particles;

Dispersing the flame retardant is melting and kneading the styrene polymer and the flame retardant;

It provides a method for producing expandable polystyrene beads.

Also provided is a foam molding foamed with the expandable polystyrene beads of the present invention.

The expandable polystyrene beads of the present invention have an effect of showing excellent flame retardancy without deteriorating physical properties such as foamability.

Hereinafter, the present invention will be described in detail.

Expandable polystyrene beads of the present invention,

In the expandable polystyrene beads in which the flame retardant is dispersed in the styrene-based polymer, the flame retardant is characterized in that it comprises a silicon-based powder and expanded vermiculite powder.

The styrene-based polymer may be polystyrene. Alternatively, the styrenic polymer may be made of a polymer of styrene and at least one comonomer. Examples of the comonomer include ethylenically unsaturated monomers, alkylstyrenes, divinylbenzenes, acrylonitrile, alphamethylstyrene, and methylmethacryl. At least one compound selected from methyl methacrylate and vinyl acrylate monomers may be used.

The styrenic polymer preferably has a physical property such that the density of the entire foamed particles after foaming can be in the range of about 5 g / l to about 20 g / l. In this case, the foamed styrene-based polymer can exhibit more excellent thermal insulation. As the styrenic polymer having a physical property in which the density of the whole particle may be in the range of about 5 g / l to about 20 g / l after foaming, specific examples include polystyrene having a weight average molecular weight of about 100,000 to about 400,000. Can be.

In addition to the shape and size of the styrene-based polymer is not particularly limited. Typically, the average particle size of the styrene-based polymer may be about 0.3 to about 3 mm. In addition, the styrenic polymer may typically be in the form of spherical or elliptical particles.

In the expandable polystyrene beads of the present invention, the silicon-based powder is included as a flame retardant and is dispersed in the styrene-based polymer.

The silicon-based powder is not limited in average particle size, but is preferably about 30 to about 150 μm, more preferably about 40 to about 50 μm in terms of kneading with the styrenic polymer.

Although the type of the silicon-based powder is not particularly limited, the silicon-based powder is, in terms of compatibility with the styrene-based polymer, dimethylsiloxane having a dimethylvinyl group at the terminal, and silica surface-treated with methacryloxypropyltrimethoxysilane It is preferable to include. In particular, silica has a strong inorganic properties, and may be somewhat less compatible with the polymer, it can be improved by treating the surface with methacryloxypropyl trimethoxysilane.

The silicon-based powder is preferably contained 2 to 20 parts by weight based on 100 parts by weight of the styrene-based polymer, in particular, the dimethylsiloxane having a dimethylvinyl group at the terminal, and methacryloxypropyltrimethoxysilane In the case of containing the surface-treated silica, based on 100 parts by weight of the silicon-based powder, 30 to 70 parts by weight of dimethylsiloxane having a dimethylvinyl group at the end, and 30 to 70 silicas treated with methacryloxypropyltrimethoxysilane It is suitable to include parts by weight. If the silica is included more than the above range than the siloxane, it may be undesirable in terms of compatibility of the silicon-based powder and the styrene-based polymer, and if less silica is included than the siloxane, the flame retardant performance is improved It may be insignificant and may be undesirable.

Expanded vermiculite powder is included as a flame retardant and is dispersed in the styrene-based polymer.

Expanded vermiculite, which is used as a main flame retardant in the expandable polystyrene beads of the present invention, is a clay mineral having an inset layered structure, and generally refers to a hydrous mica that is a modified product of gold mica and biotite. Also known as vermiculite. When the vermiculite is expanded by heat treatment, it expands by about 6 to 20 times depending on the condition of the heat treatment and the properties of the raw material. Thus, the expanded and expanded vermiculite is "expanded vermiculite". Expanded vermiculite has low specific gravity, excellent heat insulating properties and sound insulation, and is used as a heat insulating material, aggregate of lightweight concrete, sound absorbing material and the like.

If the particle size of the expanded vermiculite powder is too small, it may be difficult to obtain satisfactory levels of insulation and flame retardancy because of poor absorption and ion exchange capacity. In addition, during foaming of the expandable polystyrene beads, a decrease in strength and dimensional stability due to shrinkage of the product may occur.

On the other hand, if the particle size of the expanded vermiculite powder is too large, the vermiculite may not be smoothly introduced into the styrenic polymer, the styrene-based polymer may not contain an appropriate amount of blowing agent, and the shape of the polystyrene particles may not be round. have. In this case, foaming of the expandable polystyrene beads may not be easy, and even if foamed, workability, strength, dimensional stability, and the like may be reduced.

Thus, for example, the average particle size of the expanded vermiculite powder is preferably about 30 to about 150 μm, more preferably about 40 to about 50 μm.

If the content of the expanded vermiculite powder is too small, the effect of improving the flame retardancy may be weak. In addition, the strength and dimensional stability of the core material may be reduced after molding, and the flame retardancy may be insufficient because it does not automatically perform the role of extinguishing fire.

On the other hand, if the content of the expanded vermiculite powder is too large, the size of the polymerized polystyrene particles may be excessively small when preparing expandable polystyrene beads by suspension polymerization in the presence of the expanded vermiculite powder. In addition, the polymerized polystyrene particles have the form of needles having a high aspect ratio, and in severe cases, the polymerization itself may fail. In addition, during foaming, the adhesion between the foamed polystyrene beads may be excessively lowered. In this case, the polystyrene foam molded article suffers from shrinkage due to low fusion, not only to maintain the original shape of the product, but also to agglomerate of expanded vermiculite powder, resulting in a very poor quality of the polystyrene foam molded article.

Thus, for example, the content of the expanded vermiculite powder is preferably about 2 to about 20 parts by weight based on 100 parts by weight of the styrenic polymer.

In the expandable polystyrene beads of the present invention, the styrene-based polymer may further include a blowing agent.

The blowing agent is impregnated in the styrene-based polymer, and in a later foaming process, serves to promote foaming of the styrene-based polymer.

Although a blowing agent is not specifically limited, It is preferable to use a flame retardant and nonflammable compound whenever possible. That is, although the blowing agent included in the expandable polystyrene beads may be used an aliphatic hydrocarbon compound having 4 to 6 carbon atoms (for example, butane and pentane) commonly used, the polystyrene beads of the present invention are flame retardant and non-flammable in order to maximize flame retardancy It is preferred to use the compound as blowing agent. As examples of blowing agents that can be preferably used in the present invention, very reactive non-flammable, inert gas (inert gas) and the like can be used, and specifically, one or more selected from carbon dioxide, nitrogen, helium, neon, and argon can be used. Can be. The incombustible, inert gas is also highly desirable in terms of the foaming stability of styrene.

The content of the blowing agent may be, for example, about 3 to about 8 parts by weight based on 100 parts by weight of the styrenic polymer. Preferably, the content of blowing agent may be adjusted such that the foamed styrenic polymer has a density in the range of about 5 g / l to about 20 g / l.

In addition, the expandable polystyrene beads of the present invention may further include other additives such as auxiliary flame retardants and inorganic additives. Auxiliary flame retardants are used to further enhance the flame retardant effect of silicon-based powders and expanded vermiculite powders.

As the auxiliary flame retardant, conventionally used flame retardants can be used without limitation. For example, phosphorus flame retardants, bromine flame retardants, expanded graphite, or a combination thereof may be used.

As the phosphorus flame retardant, for example, inorganic or organic phosphates, phosphites or phosphonates, or red phosphorus, or a combination thereof can be used. Specific examples of the phosphorus flame retardant include diphenyl phosphate, triphenyl phosphate, diphenyl cresyl phosphate, ammonium polyphosphate, resorcinol diphenyl phosphate, melamine phosphate, dimethyl phenyl phosphonate and dimethyl methyl phosphonate. One or more compounds may be used. As the bromine flame retardant, for example, hexabromocyclododecane (HBCD), decabromo diphenyloxide (DBDPO), or a combination thereof may be used.

Another embodiment of the expandable polystyrene beads of the present invention may further comprise an inorganic filler. Through the additional use of inorganic fillers, the strength and dimensional safety of foamed polystyrene foam molded articles can be further improved.

As the inorganic filler, for example, talc, aluminum hydroxide, magnesium hydroxide, calcium carbonate, graphite, metal powder (eg, spherical or plate aluminum powder), or a combination thereof can be used.

If the content of the inorganic filler is too small, the addition effect may be weak. If the content of the inorganic filler is too excessive, the adhesion may be reduced during the foam molding process of the styrene beads. For example, the content of the inorganic filler is preferably about 0.1 to about 30 parts by weight, more preferably about 1 to about 10 parts by weight based on 100 parts by weight of the styrene polymer.

In addition, the method for producing the expandable polystyrene beads of the present invention,

Dispersing a flame retardant comprising silicon-based powder and expanded vermiculite powder in the styrene polymer particles, and incorporating a blowing agent in the styrene polymer particles;

Dispersing the flame retardant is melting and kneading the styrene polymer and the flame retardant;

It is characterized by.

In the past, a flame retardant was added before or during styrene monomer suspension polymerization. In this case, when an excessive amount of flame retardant is added, there is a limit to the uniform dispersion of the flame retardant and the suspension polymerization itself does not proceed smoothly. There was this. Accordingly, the method for preparing expandable polystyrene beads of the present invention is to disperse the flame retardant in the polymerized styrene polymer without adding a flame retardant before suspension polymerization or polymerization of the styrene monomer. In this way, the excess flame retardant can be dispersed in the styrene polymer regardless of polymerization.

In particular, when the flame retardant is dispersed in the styrene polymer, the styrene polymer and the flame retardant may be melted and kneaded. Although not necessarily limited thereto, melting and kneading of the styrene polymer and the flame retardant can be easily performed by an extruder. The extruder may use a conventional extruder widely used in the art and is not particularly limited.

Hereinafter, the expandable polystyrene beads of the present invention and the manufacturing method of the present invention will be described in more detail with reference to Examples. It is apparent that the following examples are intended for more detailed description of the invention and are not intended to limit the scope thereby.

Example

2 kg of polystyrene (LG Chemical GPPS 25SPE) and 2.0 kg of silicon-based powder (including dimethylsiloxane having a dimethylvinyl group at the end, and methacryloxypropyltrimethoxysilane in 1: 1 weight ratio) and 1.0 kg of expanded vermiculite was mixed at room temperature, and then a mixture pellet in which silicon-based powder and expanded vermiculite was uniformly mixed in a styrene polymer resin was prepared using a twin screw extruder. The prepared pellet was introduced into a foaming extruder and then kneaded by injecting a carbon dioxide blowing agent while heating and melting at a temperature of 210 ° C. A flame retardant foam was obtained while slowly cooling the composition in the molten state to 135 ° C. The foamability was excellent and the density of the foam was about 0.06 g / cm 3.

Comparative example  One

A flame retardant foam was obtained in the same manner as in Example 1, except that 3 kg of silicone powder was used alone as a flame retardant in 20.0 kg of polystyrene. The foamability was excellent and the density of the foam was about 0.06 g / cm 3.

Comparative example  2

A flame retardant foam was obtained in the same manner as in Example 1 except that 3 kg of expanded vermiculite powder was used alone as a flame retardant in 20.0 kg of polystyrene. The foamability was excellent and the density of the foam was about 0.06 g / cm 3.

Comparative example  3

A flame-retardant foam was obtained in the same manner as in Example 1 except that 20 kg of polystyrene was used alone without adding a flame retardant. The foamability was excellent and the density of the foam was about 0.06 g / cm 3.

Experimental Example  -[Flame Retardant Test]

The flame retardancy test was done about the said Example and Comparative Examples 1-3. The flame retardancy test was carried out in a manner of measuring the combustion time, and the mold holding time, the test conditions were as follows, the results were as shown in Table 1.

Test condition

After the flame was ignited by the methane gas supply, the flame size was fixed to 20 mm. The flame temperature took 44 ± 2 seconds to rise to 700 ± 3 ° C. The specimens of Examples and Comparative Examples were prepared in the form of strands having a diameter of 8 mm and a length of 100 mm, and the specimens were fixed in clamps, and then the flame was heated for 5 seconds, and the combustion time and the mold holding time were measured.

The combustion time is the time taken for the sample to burn out, and the mold holding time is defined as the time taken for the sample to melt and separate without maintaining the mold. In other words, the longer the combustion time and the mold holding time, the less likely to burn.

Burning time (s / 10㎝) Mold holding time (s) Example 61.6 18.3 Comparative Example 1 44.3 19.7 Comparative Example 2 63.0 9.7 Comparative Example 3 48.7 6.7

In the case of using only silicon powder (Comparative Example 1), the mold holding time value was high, but the combustion time value was somewhat low. This indicates a high possibility of ignition and is not good in terms of flame retardancy.

In contrast, in the case of using only expanded vermiculite (Comparative Example 2), the combustion time value was high, but the mold holding time value was low. This is rather poor in terms of flame retardancy because the possibility of ignition is somewhat low, but the expanded polystyrene molded body cannot have a rigid structure by heat.

In the case where no flame retardant was added (Comparative Example 3), both the combustion time and the mold holding time were low, indicating very low flame retardancy.

In contrast to the comparative examples, in the case of the embodiment, both the combustion time and the mold holding time were excellently measured, indicating that the flame retardancy was very high.

Claims (10)

An expandable polystyrene bead in which a flame retardant is dispersed in a styrenic polymer, wherein the flame retardant comprises silicon powder and expanded vermiculite powder. According to claim 1, The silicone-based powder, expandable polystyrene beads, characterized in that contained 2 to 20 parts by weight based on 100 parts by weight of the styrene-based polymer. 2. The expandable polystyrene bead according to claim 1, wherein the silicon-based powder comprises dimethylsiloxane having a dimethylvinyl group at its end, and silica which has been surface treated with methacryloxypropyltrimethoxysilane. 4. The expandable polystyrene beads according to claim 3, wherein the silicon powder comprises 30 to 70 parts by weight of dimethyl siloxane and 30 to 70 parts by weight of methacryloxypropyltrimethoxysilane, based on 100 parts by weight of the silicon powder. . The expanded polystyrene bead according to claim 1, wherein the expanded vermiculite powder is included in an amount of 2 to 20 parts by weight based on 100 parts by weight of the styrene-based polymer. The foamable polystyrene bead of claim 1, wherein the styrene-based polymer further comprises a blowing agent. 7. The expandable polystyrene beads according to claim 6, wherein the blowing agent is at least one selected from carbon dioxide, nitrogen, helium, neon, and argon. Dispersing a flame retardant comprising silicon-based powder and expanded vermiculite powder in the styrene polymer particles, and incorporating a blowing agent in the styrene polymer particles; Dispersing the flame retardant is melting and kneading the styrene polymer and the flame retardant; Method for producing expandable polystyrene beads, characterized in that. The method for producing expandable polystyrene beads according to claim 8, wherein the styrene polymer and the flame retardant are melted and kneaded by an extruder. Foam moldings foamed with the expandable polystyrene beads of claim 1.