KR100878775B1 - Polystrene foam bead improved its incombustibility and polystyrene foam using thereof and method for producing the same - Google Patents

Abstract

The present invention relates to expandable polystyrene beads with improved flame retardancy, polystyrene foams using the same, and a method of manufacturing the same, by adding and mixing 0.5-50 wt% and 1-5 wt% of an adhesive binder to a polymer polystyrene beads. It characterized in that it comprises the step of coating the zinc powder on the polystyrene beads, the polystyrene foam can be obtained greatly improved flame retardancy by the present invention, in particular flame retardant class 3 as defined in KSF 2271, which was not possible in the prior art as well as flame retardant 2 Polystyrene foams with class standards and fire resistance have been obtained.

Polystyrene, flame retardant, fire resistant, zinc powder, sodium silicate, styrofoam, vinyl acetate resin, acrylic resin

Description

Foamed polystyrene beads with improved flame retardancy and polystyrene foams using the same, and methods for preparing the same {Polystrene foam bead improved its incombustibility and polystyrene foam using approximately and method for producing the same}

1 is a photograph of a bead coated with zinc powder according to an embodiment of the present invention.

The present invention relates to foamed polystyrene beads with improved flame retardancy, polystyrene foams using the same, and a method of manufacturing the same.

Molded polystyrene foam (styrofoam) is widely used as a heat insulating material for the insulation of buildings. Molded polystyrene foams have the disadvantage of lacking flame retardancy despite good thermal insulation and workability. Conventionally, halogen-based flame retardant HBCD (HEXA BROMO CYCLO DODECAN, hereinafter referred to as “HBCD”) has been mainly used to improve the flame retardancy.

Recently, the halogen-based flame retardant HBCD is not environmentally friendly and is regulated in various countries around the world, and its use is gradually decreasing in Korea.

For this reason, Korean Patent Laid-Open Publication No. 2001-0080720 provides suitable styrene in suspension with a blowing agent before, during or after polymerization in the presence of 5 to 50% by weight of expanded graphite to impart flame retardancy. A method for producing expanded styrene beads by polymerizing with monomers is disclosed.

However, this technique has a problem in that the foamability of the obtained expanded styrene beads is insufficient, and the adhesion between the foamed particles is insufficient when foaming and molding by inserting the beads into the mold and steam, the graphite particles and the molded body There existed a problem of molding workability, such as sticking. In addition, since the hygroscopicity of the molded article is high, the thermal insulation property is deteriorated with time, the flame retardancy is also insufficient, and there is a problem that a separate flame retardant (takeover) must be used.

On the other hand, foams made from expanded polystyrene beads and used for thermal insulation have a density of at least 30 g / l, which is a density at which the thermal conductivity of the expanded polystyrene foam is minimal. In order to reduce the material, it is preferable to use a foam having a low density, in particular, about 15 to 20 g / L, but in this case, there is a problem that the heat insulating performance is lowered and the value as a heat insulating material is lost. As a conventional technique for solving such a problem, Korean Patent Laid-Open No. 2004-0073277 may be mentioned.

It includes a volatile blowing agent comprising 0.1 to 25 weight percent graphite particles or carbon black particles, and a mixture of 2.2 to 6 weight percent pentane and 1 to 10 weight percent water, based on the expandable styrene polymer beads (EPS beads). Expandable styrene polymer beads having a density in excess of 600 g / l are disclosed. Through this technique, it is possible to obtain a polystyrene foam having a density of 10 to 15 g / l, but which does not significantly lower the thermal insulation performance.

However, this technique also has a problem in that moldability, like the prior art, lacks the effect of improving heat insulation and flame retardancy.

The present invention is to solve the problems described above, it is an object of the present invention to provide a flame retardant polystyrene bead that can produce a polystyrene foam having a flame retardant class 3 or more flame retardant prescribed in KSF 2271. It is still another object of the present invention to provide a polystyrene foam having a significantly improved flame retardancy using such polystyrene beads. Another object of the present invention is to provide a flame retardant polystyrene foam (styrofoam) which is harmless to the environment. Another object of the present invention is to provide a flame retardant polystyrene bead having improved moldability.

The present invention comprises the addition of 0.5 to 50% by weight of zinc powder, more preferably 3 to 15% by weight, to the polymerization product or to the polymerized beads before, during or after the polystyrene polymerization step. If the amount is less than this range, the effect of injecting is insufficient, and if the range is exceeded, a problem occurs in workability.

The method of 'before or during the polymerization step' is disclosed in Korean Patent No. 492199, by adding a peroxide initiator in the presence of zinc powder having an average particle size of 1 to 50 μm together with 15 to 30% by weight of comonomer. The polymerization may be carried out in an aqueous suspension, by adding a blowing agent during the polymerization, before the polymerization.

The 'after polymerization' method uses a two-stage reactor to polymerize styrene monomer in a one-stage reactor to form beads, and then spray zinc powder as it is transferred to the two-stage reactor to surface the semi-melt bead particles. It is a method to coat the zinc powder on. In the former method, the zinc powder is spread evenly over the beads. In the latter method, the zinc powder is concentrated on the surface of the beads.

In addition, the method of 'after the polymerization step' includes a method of coating the zinc powder using an adhesive binder on the surface of the bead is cooled.

Beads obtained in this way are somewhat inferior in thermal insulation compared to beads obtained by the prior art to which graphite or carbon is added, but greatly improve the flame retardancy, especially the durability is remarkably improved.

The method for producing a polystyrene foam of the present invention is subjected to the steps of foaming and molding the beads containing zinc powder in a conventional manner, or coating and drying with a sodium silicate-based binder before molding. The term “silicate binder” refers to a mixture of liquids having improved water resistance by adding sodium silicate alone or sodium silicate and adding calcium compounds and / or potassium compounds.

The content of solids in the liquid mixture is about 35-50% by weight. When the content of solids exceeds this, the viscosity is too high, making coating difficult, and if it is less than this range, the viscosity is too low, which makes coating difficult and at the same time takes a lot of drying time.

The most effective method of containing zinc powder in polystyrene beads is to coat the zinc powder on the surface of the beads. Preferred examples of the method for coating the zinc powder include placing the beads and the zinc powder in a mixer and adding and mixing an adhesive binder in a range of 1-5% by weight of the beads. When the amount of the adhesive binder is less than the above range, the adhesiveness is insufficient, even if the above range is exceeded, there is no further effect of improving the adhesiveness, but rather the physical property decreases and the drying time increases.

The type of mixer is preferably a rotating drum mixer in which the mixer itself rotates, but a screw mixer in which a screw is installed inside the mixer can also be used.

Since zinc powder is highly reactive, adhesive binders can be used without being strong in acidity or alkalinity. Examples of adhesive binders that can be used are those that are water-soluble and adhesive such as acrylic resins, vinyl acetate resins, etc., and have a slightly acidic or weak alkalinity of about 4-5 or 8-10.

Zinc reacts well with acids and alkalis. In case of strong acidity or alkalinity, zinc reacts rapidly with exothermic reactions to form zincate, which is inappropriate for adhesive binders with acidity in the above range. The reaction takes place so that it is strongly electrodeposited with the bead surface. If the zinc powder is not strongly electrodeposited with the surface of the bead, there is a problem that the coated zinc powder is dropped during the foaming process and the conveying process of the high pressure steam is used.

If necessary, pigments such as ferric oxide, ferric oxide, silica sand, titanium and the like may be added. The amount of the pigment used is within 50% by weight of the zinc powder, more preferably within 30% by weight. In the case of exceeding this range, the electrodeposition property is lowered, which causes a problem that the coated zinc powder is dropped during the foaming or conveying process.

When the beads, the zinc powder and the adhesive binder are put into a mixer and mixed, the zinc powder is uniformly coated on the surface of the bead, and after being completely dried, a dark gray shiny coating layer is stably formed (FIG. 1). Reference). In order to promote electrodeposition and drying of the zinc powder, the temperature inside the mixer can be maintained in the range of 40-50 ° C. If it exceeds this range, there is a possibility that the beads will be foamed by vaporization of pentane or butane in the coating.

The beads having the zinc powder coated thereon are obtained as shaped bodies (styrofoam) by undergoing a first pre-expanding step and a second step of foaming in a molding machine as usual. In the case where the coating amount of zinc powder is 3% by weight or more, the obtained molded article has a flame retardant level of flame retardant level 3 on the basis of the Korea Disaster Prevention Test even if it is foam molded according to the conventional method without any treatment. In addition, since the beads coated with zinc powder are very stable, they may be distributed in this state as well as the beads containing zinc powder therein.

The coating of the primary foam of the zinc powder coated beads with a silicic acid-based binder may be performed by placing the beads and the binder in a blender and rotating the blender or by placing the beads and the binder in a blender with agitator. The mixing ratio of beads and binder is 1: 1-4. If it is less than this range, the flame retardance of the obtained molded object will be lacking, and the effect of increasing moldability will also be lacking. When it exceeds this range, not only the coating itself is difficult, but also the density of the obtained molded object increases too much.

The coated beads are dried in a conventional manner and transferred to a flat plate molding machine.

Beads transferred to the flat plate molding machine is foamed and fusion is completed by applying steam as in the usual method to form a molded body (styrofoam). As described above, the molded article made of beads coated with a zinc powder coating and a silicic acid-based binder has fire resistance far exceeding the second flame retardant level recognized as being usable as a building interior material based on the Korean Disaster Prevention Test standard.

An embodiment of the present invention is as follows.

(Example 1)

* Production of beads containing zinc powder 1

2.5Kg of polystyrene (GPPS 158K from BASF) was dissolved in 17Kg of styrene, 180g of zinc powder having an average particle diameter of 10 µm was added, and 60g of dicumyl peroxide and 20g of dibenzoyl peroxide were added and suspended uniformly in the solution.

The organic phase was incorporated into 20 L deionized water in a 50 L stirred vessel and 200 g of pentane was added as a suspension and then heated to 80 ° C. After 150 minutes 3.5 g of emulsifier K 30/40 (Bayer AG) were added.

After 30 minutes additional 1190 g of pentane were added and the polymerization was completed at 135 ° C. The aqueous phase was separated to give gray beads with an average diameter of 0.87 mm.

(Example 2)

* Manufacture of zinc powder containing beads 2

In the same manner as in Example 1, zinc powder was added to 700 g to obtain beads.

(Example 3)

* Production of zinc powder-containing beads 3

In the same manner as in Example 1, zinc powder was added to 950 g to obtain beads.

(Example 4)

* Manufacture of zinc powder coated beads 1

19.5 Kg of polystyrene (GPPS 158K from BASF), 60 g of dicumyl peroxide and 20 g of dibenzoyl peroxide were added to uniformly suspension suspension in solution. The organic phase was incorporated into 20 L deionized water in a 50 L stirred vessel. 200 g of pentane was added to the suspension and then heated to 80 ° C. After 150 minutes 3.5 g of emulsifier K 30/40 (Bayer AG) were added. After 30 minutes, additional 1190 g of pentane was added and the temperature was raised to 135 ° C., and then transferred to another reactor through a rotary transfer furnace before the polymerization was completed, and zinc having the same particle size as that used in Example 1 during the transfer was obtained. Powder was sprayed. The aqueous phase was separated to give gray beads with an average diameter of 0.89 mm. The content of the coated zinc powder was 8.2% by weight.

(Example 5)

* Manufacture of Zinc Powder Coated Beads 2

30 kg of polystyrene beads for panel (Kumho Petrochemical Co., Ltd., product name: N16) and 60 g of vinyl acetate resin (PH4.5 solid content 42% by weight) are put in a screw-type mixer with an adhesive binder and mixed for 10 minutes on the surface of the beads. The adhesive binder was first coated, and then 3 kg of zinc powder used in Example 1 was added, and the mixture was stirred for 10 minutes while maintaining the temperature inside the blender at 40 ° C. to give the shiny light gray beads coated with zinc powder. Obtained (Fig. 1). The coated zinc powder layer was so strong that it did not come out even when rubbed by hand, it was bound to the beads.

(Example 6)

* Manufacturing of molded article 1

The beads obtained in Example 1 were used to complete primary foaming and secondary foaming (molding) using steam in a conventional manner. The bulk density (BULK DENSITY) of the obtained molded body was 14.8 g / l, and the thermal conductivity was 38 mW / m.K as measured at 10 ° C. according to DIN 52612. The flame retardancy was improved considerably compared to the use of conventional beads, but it did not meet the KSF 2271 standard for flame retardancy of the building materials and structure. Also, the adhesion between the beads was somewhat poorer than the conventional beads.

* Flame retardant class 3 standard prescribed in KSF 2271

-Temperature time area (℃ X minutes, after 3 minutes): 350 or less

-Smoke coefficient (CA): 120 or less

Afterglow time (sec): less than 30

-No hazards such as fire hazard: no

-Mouse down time: 9 minutes or more

-Melt disappearance over the whole thickness: no

-Crack width on the back: thickness less than 1/10

(Example 7)

* Manufacturing of molded article 2

The beads obtained according to Example 1 were used, and after the first foaming, the beads were silicic acid-based binders (100 parts by weight of sodium silicate and 2 parts by weight of 30% potassium carbonate aqueous solution) as described in Korean Patent Application No. 10-2005-38061. And a binder added with 1 part by weight of calcium carbonate). The ratio of beads and binder was mixed at a weight ratio of 1: 1 and placed in a rotary stirrer, stirred for 2 minutes, and then coated and dried by passing through a tunnel drying furnace. The dried beads were placed in a flat plate molding machine and foamed and molded in a conventional manner using steam to obtain a molded article having a bulk density of 22.6 g / l.

The thermal conductivity of the obtained molded object was 31 mW / m.K as measured at 10 degreeC according to DIN 52612. Flame retardant passed the standard of flame retardant grade 3. The adhesion between beads is considerably improved over Example 6.

(Example 8)

* Manufacturing of molded article 3

The same procedure as in Example 6 was carried out, but the beads used in Example 2 were used. The thermal conductivity of the obtained molded article was 33 mW / m.K as measured at 10 ° C in accordance with DIN 52612. Flame retardant passed the standard of flame retardant grade 3. The adhesion between the beads was similar to that of Example 6.

(Example 9)

* Manufacturing of molded article 4

In the same manner as in Example 7, the amount of binder was increased three times, and the coating process was also performed twice. That is, the coating was dried once and then slightly dried. The thermal conductivity of the obtained molded article was 31 mW / m.K as measured at 10 ° C in accordance with DIN 52612. The flame retardancy passed the standard of KSF 2271 flame retardant class 2 (semi-combustible material). The adhesion between the beads was also good.

* Flame retardant class 2 standard prescribed in KSF 2271

-Temperature time area (℃ X minutes, after 3 minutes): 100 or less

-Smoke coefficient (CA): 60 or less

-Melt extinction over the entire thickness: no

-Crack width at back side (mm): thickness less than 1/10

-Harmful deformation in fire: no

-Mouse down time: 9 minutes or more

(Example 10)

 * Manufacturing of molded article 5

The same procedure as in Example 9 was carried out except that beads obtained by Example 3 were used. The flame retardance of the obtained beads greatly exceeded the criteria of flame retardant class 2. The surface of the molded body was heated at a temperature of 1050 ° C. for 15 minutes, but the surface of the molded body was damaged by only about 5 mm at the beginning of heating, and at this time, the molded body was not damaged but changed to the surface only by the zinc-ceramic film formed on the surface. In addition, there was no smoke even when heated continuously. This can be interpreted that the obtained molded article has fire resistance.

(Example 11)

* Manufacturing of molded articles6

The beads obtained in Example 4 were coated with a silicic acid-based binder in the same manner as in Example 9 to obtain a molded article, which passed the flame retardant class 2 standard, and the adhesion between the beads was similar to that of Example 9.

(Example 12)

* Manufacturing of shaped bodies7

The beads obtained in Example 5 were subjected to the same procedure as in Example 9 to obtain a molded article. The flame retardance of the obtained molded article had fire resistance as in the molded article obtained in Example 10.

(Comparative Example 1)

The same procedure as in Example 1 was carried out in the same manner as in Example 6, except that beads (BARSF Co., Ltd. product name Neopole) obtained by adding expanded graphite instead of zinc powder were used to obtain a molded article. The bulk density (BULK DENSITY) of the obtained molded body was 13.9 g / l, and the thermal conductivity was 34 mW / m.K as measured at 10 ° C. according to DIN 52612. The flame retardancy was somewhat improved compared to the use of the conventional beads, but was considerably insufficient than the molded article obtained in Example 6. Also, the adhesion between the beads was somewhat poor.

(Comparative Example 2)

The same procedure as in Example 2 was carried out in the same manner as in Example 6 except that beads (Kumho Petrochemical Co., Ltd. trade name Enerpol) obtained using expandable graphite were used instead of zinc powder to obtain a molded article. The bulk density (BULK DENSITY) of the obtained molded body was 13.5 g / l, and the thermal conductivity was 35 mW / m.K as measured at 10 ° C. according to DIN 52612.

The flame retardancy was somewhat improved compared to the use of the conventional beads, but was considerably insufficient than the molded article obtained in Example 6. Also, the adhesion between the beads was somewhat poor.

(Example 12)

* Manufacturing of shaped bodies8

The beads obtained in Example 1 were used, and the beads were coated using a caylic acid solution (solid content 40%). The ratio of beads and binder was mixed at a weight ratio of 1: 1 and placed in a rotary stirrer, stirred for 2 minutes, and then coated and dried by passing through a tunnel drying furnace. The dried beads were placed in a flat plate molding machine and foamed and molded in a conventional manner using steam to obtain a molded article having a bulk density of 22.1 g / l. The thermal conductivity of the obtained molded article was 33 mW / m.K as measured at 10 ° C in accordance with DIN 52612. Flame retardant passed the standard of flame retardant grade 3. The adhesion between the beads was worse than that of Example 7 and Example 8

(Example 13)

* Manufacturing of shaped bodies9

The beads obtained in Example 1 were used, and the beads were coated using a sodium silicate solution (solid content 40%). The ratio of beads and binder was mixed at a weight ratio of 1: 1 and placed in a rotary stirrer, stirred for 2 minutes, and then coated and dried by passing through a tunnel drying furnace. The dried beads were placed in a flat plate molding machine and foamed and molded in a conventional manner using steam to obtain a molded article having a bulk density of 22.0 g / l.

The thermal conductivity of the obtained molded object was 35 mW / m.K as a result of measuring at 10 degreeC according to DIN 52612. Flame retardancy has passed the KSF2271 flame retardant class 3 standard. The adhesion between the beads was less than that of Example 12.

According to the present invention, it is possible to obtain a polystyrene foam having greatly improved flame retardancy, and in particular, to obtain a polystyrene foam having a flame retardant class 3 as well as a flame retardant class 2 standard, and fire resistance, which are conventionally impossible in KSF 2271. Therefore, styrofoam can be effectively used not only for sandwich panels but also as interior materials for buildings. In addition, since the polystyrene molded article having fire resistance and light weight can be obtained by the present invention, it can be widely applied to the construction industry field where light weight and heat insulation are simultaneously required.

Claims (13)

delete delete Adding 0.5-50% by weight and 1-5% by weight of an adhesive binder having an average particle size of 1 to 50 µm to the polymerized polystyrene beads and mixing them so that the zinc powder is coated on the polystyrene beads. Process for producing polystyrene beads The method of claim 3, wherein the adhesive binder has a pH of 4-5 or 8-10. The method for producing polystyrene beads according to claim 3, wherein the temperature at the time of mixing is 40-50 ° C. The method for producing polystyrene beads according to claim 3 or 4, wherein the adhesive binder is one selected from vinyl acetate resin and acrylic resin. delete The polystyrene beads coated with 0.5-50% by weight of zinc powder having an average particle size of 1 to 50 µm are foamed and molded by a conventional method of primary foaming and secondary foaming (molding) with high pressure and high temperature steam. Method of producing a flame retardant polystyrene foam. The method of manufacturing a flame retardant polystyrene foam according to claim 8, wherein after the first foaming, the beads are coated with a sodium silicate-based binder, dried, and then molded. delete delete delete delete

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