KR20100110788A

KR20100110788A - Flame-retardant expandable styrene resin particle, and method for production thereof

Info

Publication number: KR20100110788A
Application number: KR1020107013599A
Authority: KR
Inventors: 마사유키 다카노; 요시노리 오자키; 가즈미 야마다
Original assignee: 세키스이가세이힝코교가부시키가이샤
Priority date: 2007-12-28
Filing date: 2008-12-18
Publication date: 2010-10-13
Also published as: TWI428378B; CN101910267B; JPWO2009084456A1; CN101910267A; JP5433422B2; TW200934814A; WO2009084456A1

Abstract

In suspension polymerization of a styrene monomer to obtain styrene resin particles, 0.45 to 2.0 parts by weight of tetrabromo cyclooctane is added to 100 parts by weight of the styrene monomer, and then during suspension polymerization of the styrene monomer. Or a flame-retardant foamable styrene resin particle is obtained by impregnating the styrenic resin particle with the physical blowing agent after the suspension polymerization while adjusting the impregnation temperature to 80-110 ° C. to obtain a flame-retardant foamable styrene resin particle.

Description

Flame retardant foamable styrene resin particles and a method for producing the same {FLAME-RETARDANT EXPANDABLE STYRENE RESIN PARTICLE, AND METHOD FOR PRODUCTION THEREOF}

The present invention relates to a flame retardant foamable styrene resin particle and a method for producing the same. More specifically, the present invention relates to a flame retardant foamable styrene resin particle using tetrabromo cyclooctane as a flame retardant and a method for producing the same.

BACKGROUND ART Conventionally, styrene-based resin foamed molded articles have been widely used in building materials because of their excellent strength and heat insulating properties. Such a styrene resin foamed molded article is subjected to suspension polymerization of a styrene monomer to obtain styrene resin particles, impregnating the obtained styrene resin particles with a physical foaming agent to obtain expandable styrene resin particles, and prefoaming the obtained expandable styrene resin particles. The styrene resin prefoamed particles were obtained, the obtained prefoamed particles were filled into a mold having a desired shape and foamed, and the prefoamed particles were produced by thermal fusion-integrating by their foaming pressure.

On the other hand, the styrene-based resin foamed molded article has a problem that it is easily burned. In particular, when used for building materials, it may cause combustion in case of fire. Therefore, the problem is solved by adding a flame retardant to a styrene resin foam molded object.

As a method of adding a flame retardant, a method of dissolving in a styrene monomer or a method of impregnating a styrene resin particle with the impregnation of a physical blowing agent is known. As the former method, there exist the method of Unexamined-Japanese-Patent No. 2003-335891 (patent document 1) and Unexamined-Japanese-Patent No. 2002-194130 (patent document 2). As the latter method, Unexamined-Japanese-Patent No. 6-18918 (patent document). 3) and Japanese Patent Application Laid-Open No. 2007-246606 (Patent Document 4).

Japanese Patent Laid-Open No. 2003-335891 Japanese Laid-Open Patent Publication No. 2002-194130 Japanese Patent Publication No. 6-18918 Japanese Patent Laid-Open No. 2007-246606

In the former method, hexabromo cyclododecane (HBCD) is mainly used as a flame retardant. HBCD is a substance which is concerned about accumulation in a living body, and it is desired to reduce its use. In the latter method, since the styrene resin particles are impregnated with a flame retardant, the impregnation amount is limited, and it is desired to improve the flame retardancy by impregnating more flame retardants.

Moreover, when a large amount of a flame retardant is contained in styrene resin particle, a flame retardant acts as a nucleating agent and there exists a subject that the bubble diameter of the styrene resin foam obtained becomes too small. This problem particularly adversely affects the latter method. That is, in the latter method, since many flame retardants exist in the vicinity of the surface of the styrene resin particles, bubbles formed in the pre-expanded particles are reduced only in the surface layer portion. As a result, bubbles may not withstand the heat at the time of obtaining a foamed molded object by molding, and melting may occur, which may adversely affect the appearance of the foamed molded article. Moreover, since many flame retardants existed in the vicinity of the surface of a styrene resin particle, what was called a tendency to generate | occur | produce so-called blocking by which the prefoamed particle fuses and couple | bonds at the time of prefoaming with a flame retardant. In addition, the flame retardant caused secondary aggregation in the blowing agent impregnation solution, resulting in uneven dispersion of the flame retardant. As a result, absorption of the flame retardant into the styrene resin particles may be nonuniform. By non-uniform absorption, the particle | grains which absorbed many flame retardants exist in some parts, and the particle becomes inferior to heat resistance. For this reason, it may not be able to withstand the heating at the time of molding a foamed molded article, and may shrink and become hardened particles. The foamed molded article is usually molded by nichrome cut into a predetermined shape, but at that time, nichrome wire is splashed by the hardened particles, and uneven stripes are generated on the nichrome cut surface, which may cause a significant decrease in the value of the product. Moreover, there existed a possibility that sufficient adhesive strength may not be acquired in the use which bonds a foamed molded article and a panel by uneven stripe.

Moreover, there also exists a subject that the thermal fusion property of styrene resin preexpanded particle | grains falls.

The inventors of the present invention, when the specific flame retardant is used in a specific amount, and the impregnation temperature of the physical foaming agent is foamed to a specific temperature, the foamed styrene resin capable of obtaining a foamed molded article having excellent heat fusion properties and excellent flame retardancy between particles It was found that the particles could be provided and the invention was reached.

In this way, according to the present invention, in the suspension polymerization of the styrene monomer to obtain styrene resin particles, 0.45 to 2.0 parts by weight of tetrabromo cyclooctane is added to 100 parts by weight of the styrene monomer, and then The method for producing a flame-retardant foamable styrene resin particle which obtains a flame-retardant foamable styrene resin particle by impregnating the styrenic resin particle with the physical foaming agent during the suspension polymerization or after the suspension polymerization while adjusting the impregnation temperature to 80 to 110 ° C. Is provided.

Moreover, according to this invention, it is equipped with the styrene resin particle, the physical blowing agent contained in the said styrene resin particle, and tetrabromo cyclooctane,

The tetrabromo cyclooctane is contained in the surface layer portion of the styrene resin particles, and the tetrabromo cyclooctane content is a (% by weight), and the tetrabromo cyclooctane content is contained in the entirety of the styrene resin particles. Weight%), the styrene resin particles are contained in the styrene resin particles so as to satisfy the relation

The tetrabromo cyclooctane content rate contained in the said whole styrene resin particle is 0.45-2.00 weight part with respect to 100 weight part of styrene resin particles,

When foamed by 50 times of foaming multiple times, the flame-retardant foamable styrene resin particle which gives the foam of 50-350 micrometers of average bubble diameters is provided.

According to the production method of the present invention, the bubble diameter can be controlled, there is no bubble density at the time of foaming, and flame retardant foamable styrene resin particles having good heat sealability at the time of molding can be provided.

Moreover, the dispersion stability of the monomer mixture droplet of suspension polymerization system can be improved by using surfactant at the time of suspension polymerization.

By including a flame retardant adjuvant in the monomer mixture, the flame retardancy of the expandable styrene resin particles can be improved.

By adjusting the impregnation temperature so that the foamed molded product obtained by foaming the flame retardant foamable styrene resin particles by 50 times has an average bubble diameter of 50 to 350 µm, the foamable styrene resin particles having better heat sealability can be provided.

1 is an electron micrograph of a cross section of preliminary expanded particles of Example 1. FIG.
2 is an electron micrograph of a cross section of the pre-expanded particles of Example 3. FIG.
3 is an electron micrograph of a cross section of preliminary expanded particles of Comparative Example 4. FIG.
4 is an electron micrograph of a cross section of the pre-expanded particles of Comparative Example 5. FIG.
5 is an electron micrograph of a cross section of preliminary expanded particles of Comparative Example 6. FIG.

In the present invention, first, in the suspension polymerization of the styrene monomer to obtain styrene resin particles, tetrabromo cyclooctane (TBCO) and a polymerization initiator are added to the styrene monomer.

Styrene-based monomers include styrene, α-methyl styrene, paramethyl styrene, t-butyl styrene, crawl styrene and the like. You may use these monomers individually or in mixture of 2 or more types. Among these, styrene is particularly preferable. Moreover, esters of acrylic acid and methacrylic acid, such as methyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate and cetyl methacrylate, or monomers such as acrylonitrile, dimethyl fumarate and ethyl fumarate You may copolymerize with a styrene monomer. Moreover, you may copolymerize bifunctional monomers, such as divinylbenzene and alkylene glycol dimethacrylate, with a styrene-type monomer.

TBCO is used in the range of 0.45-2.00 weight part with respect to 100 weight part of styrene monomers. Within this range, flame retardancy and thermal fusion at molding can be ensured, and bubble density can be suppressed.

It does not specifically limit as a polymerization initiator, The polymerization initiator suitable for polymerization temperature can be selected suitably. For example, benzoyl peroxide, lauroyl peroxide, t-butyl perbenzoate, t-butyl perpivalate, t-butyl peroxyisopropyl carbonate, t-butyl peroxyacetate, 2,2-di- t-butyl peroxybutane, t-butyl peroxy-3,3,5-trimethylcyclohexanoate, di-t-butyl peroxyhexahydroterephthalate, 1,1-di-t-butyl peroxy-3 And organic azooxides such as 3,5-trimethylcyclohexane, and azo compounds such as azobis isobutyronitrile and azobis dimethylvaleronitrile. You may use these polymerization initiators individually or in mixture of 2 or more types. A polymerization initiator can be used in 0.05-3.0 weight part with respect to 100 weight part of styrene monomers.

Monomer mixtures are obtained by dissolving TBCO in styrene-based monomers. The monomer mixture may contain a flame retardant aid. Examples of the flame retardant aid include cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane, and the like. A flame retardant adjuvant can use 0.1-0.5 weight part with respect to 100 weight part of styrene monomers.

The monomer mixture is dispersed in an aqueous medium and subjected to suspension polymerization.

Aqueous media include water or a mixture of water and a water soluble organic medium (eg methyl alcohol, ethyl alcohol). The aqueous medium may contain additives such as surfactants and dispersants.

As surfactant, anionic surfactant, cationic surfactant, zwitterionic surfactant, nonionic surfactant is mentioned.

As anionic surfactant, for example, sodium oleate and castor oil Fatty acid oils such as kali, alkyl sulphate ester salts such as sodium lauryl sulfate, ammonium lauryl sulfate, alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate, alkyl naphthalene sulfonates, alkanesulfonates, dialkyl sulfo succinates, alkyls Phosphoric acid ester salt, naphthalene sulfonic acid formalin condensate, polyoxyethylene alkylphenyl ether sulfate ester salt, polyoxyethylene alkyl sulfate ester salt, etc. are mentioned.

Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxysorbitan fatty acid esters, polyoxyethylene alkylamines, and glycerin fatty acid esters. And oxyethylene-oxypropylene block polymers.

As cationic surfactant, alkyl amine salts, such as lauryl amine acetate and stearyl amine acetate, quaternary ammonium salts, such as lauryl trimethyl ammonium chloride, etc. are mentioned, for example.

Examples of amphoteric ionic surfactants include lauryl dimethyl amine oxide and phosphate ester or phosphite ester surfactants.

You may use the said surfactant individually or in combination of 2 or more types. Surfactant can be used in the range of 0.002-1.0 weight part with respect to 100 weight part of aqueous media.

Examples of the dispersant include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, polyvinylpyrrolidone, and polyacrylamide, and pyrophosphoric acid. And poorly soluble inorganic salts such as magnesium, tricalcium phosphate and hydroxyapatite. You may use these dispersing agents individually or in mixture of 2 or more types. The dispersant may be used in the range of 0.2 to 10 parts by weight based on 100 parts by weight of the styrene monomer.

Styrene-based monomers are used for suspension polymerization. Suspension polymerization is normally performed at 50-120 degreeC for 1 to 20 hours. As a result of suspension polymerization, styrene resin particles can be obtained.

In addition, a flame retardant foamable styrene resin particle can be obtained by impregnating a styrenic resin particle with a physical blowing agent during suspension polymerization or after suspension polymerization. Here, the impregnation temperature at the time of impregnation is adjusted to 80-110 degreeC. By adjusting, the bubble diameter can be controlled, there is no bubble density at the time of foaming, and the flame-retardant foamable styrene resin particles which are excellent in heat sealing property at the time of shaping | molding can be provided.

Impregnation of the styrenic resin particles of the physical blowing agent during suspension polymerization can be carried out by press-fitting the physical blowing agent into the aqueous medium. Moreover, when a physical foaming agent is impregnated into styrene resin particle after suspension polymerization, styrene resin particle may be taken out and impregnated from an aqueous medium, and may be impregnated in an aqueous medium.

Physical foaming agent means the foaming agent which has a foaming function as it is, without decomposing, and a so-called volatile foaming agent corresponds. Examples of the physical blowing agent include aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane and hexane. These physical blowing agents can be used alone or in combination of two or more.

The average particle diameter of the obtained flame-retardant foamable styrene resin particles can be 0.3-2.0 mm, for example.

The flame-retardant foamable styrene resin particles become a foamed molded article through a known prefoaming step and a foam molding step. In particular, when foamed at 50 times, the average bubble diameter of the bubbles constituting the foamed molded article can be in the range of 50 to 350 m. If it is this range, the thermal fusion property of the foamed particle which comprises a foamed molded object is favorable.

In this invention, the flame-retardant foamable styrene resin particle obtained by the said method is also provided. When the flame-retardant foamable styrene resin particles have a content of tetrabromo cyclooctane contained in the surface layer portion of the particles as a (% by weight), and a content of tetrabromo cyclooctane contained in the whole particles as b (% by weight), the formula a Tetrabromo cyclooctane is included so as to satisfy the relationship of ≦ 1.1 × b. By satisfying this relationship, it is possible to provide a flame retardant foamable styrene resin particle that satisfies both flame retardancy and heat sealability. More preferably, it is a relationship represented by the formula a≤1.05xb.

Here, since tetrabromo cyclooctane content rate a contained in the surface layer part of particle | grains is difficult to measure directly, it is a value measured by the following method. That is, the test piece of thickness 0.2mm is cut out from the surface of the foamed molded object which foamed flame-retardant foamed styrene resin particle 50 times. Since the surface of a foamed molded object consists of a surface layer of a flame-retardant expanded styrene resin particle, this test piece has shown the state of the surface layer of a flame-retardant expanded styrene resin particle. The tetrabromo cyclooctane content rate a (weight%) contained in the surface layer part of particle | grains is obtained by measuring the amount of tetrabromo cyclooctane in a test piece, and calculating the ratio with respect to the test piece total weight. In addition, the detailed measuring method is described in the Example.

On the other hand, the tetrabromo cyclooctane content rate b contained in the whole particle means the ratio with respect to the styrene monomer of the tetrabromo cyclooctane amount as a raw material at the time of manufacture of flame-retardant expanded styrene resin particle.

Example

Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these Examples. In addition, the measuring methods of the molecular weight, the volume foaming drainage, the foaming drainage, the flame retardancy, the average bubble diameter, and the heat sealability of the styrene resin particles are described below.

(Molecular Weight of Styrene Resin Particles)

The weight average molecular weight (Mw) is measured using gel permeation chromatography (GPC). The measuring method is as follows. In addition, a weight average molecular weight (Mw) means the polystyrene (PS) conversion weight average molecular weight.

50 mg of the sample was dissolved in 10 ml of tetrahydrofuran (THF), filtered through a non-aqueous 0.45 μm chromatographic disk, and measured using a chromatograph. The conditions of the chromatograph are as follows.

Liquid chromatograph: Doso Corporation make, brand name "gel permeation chromatography HLC-8020"

Column: manufactured by Tosoh Corporation, trade name "TSKgel GMH-XL-L" φ 7.8 mm x 30 cm x 2

Column temperature: 40 ℃

Carrier gas: tetrahydrofuran (THF)

Carrier Gas Flow Rate: 1ml / min

Injection and pump temperature: 35 ℃

Detection: RI

Injection volume: 100 μl

Standard polystyrene for calibration curve: Showa Denko Corporation, brand name "shodex" Weight average molecular weight: 1030000 and Tosoh Corporation, weight average molecular weight: 5480000, 3840000, 355000, 102000, 37900, 9100, 2630, 870

(Volume foam drainage)

The volume foaming drainage is naturally calculated by dropping the pre-expanded particles into the measuring cylinder, and then tapping the bottom of the measuring cylinder to make the sample volume constant. Resin specific gravity is 1.0 in the case of styrene resin.

Volume foamed drainage (fold) = sample volume (ml) / sample weight (g) x resin specific gravity in the measuring cylinder

(Foam drainage)

The foamed drainage was measured by measuring the dimensions and weight of the test piece (Example 50 x 50 x 25 mm) of the foamed molded article to be at least three significant figures and calculated by the following equation. Resin specific gravity is 1.0 in the case of styrene resin.

Foam drainage (fold) = Test piece volume (cm ³ ) / Test piece weight (g) x resin specific gravity

(Flame retardant)

Five pieces of thickness 10 mm, length 200 mm, and width 25 mm are cut out from the foamed molded product as test pieces, and the fire limit leader and the burn limit leader specified in the test piece are attached. The specimen is burned with a candle for fire, to the ignition limit indicator, and the flame is retracted, and the time (seconds) from that moment until the flame disappears is measured. The time until the flame disappears does not exceed 3 second in the average of the number of the test 5, and it passes with that no one burned beyond the combustion limit leader line. In the case of normal burning, when the wick is about 10 mm in length, the flame is used to have a flame length of 50 mm or more and a thickness of about 7 mm or more.

(Average bubble diameter)

The foamed molded product is cut, and the inside of 1/10 to 9/10 or more is enlarged by a scanning electron microscope (S-3000N manufactured by Hitachi, Ltd.) 100 times from the cut surface outside of the cut surface and photographed. The photographed image is printed on the A4 sheet by four images, and the average spot t of bubbles is calculated from the number of bubbles in any straight line (length 60 mm) by the following equation. However, arbitrary straight lines should not allow bubbles to come in contact only at the contact point (when they are in contact, they are included in the number of bubbles). The measurement is made into six places.

Average spot t = 60 / (magnification of bubble number X photograph)

And bubble diameter D is computed by following Formula.

D = t / 0.616

(Thermal adhesion)

After molding, the foamed molded product is dried at 70 ° C. for 48 hours, and the vicinity of the center in the thickness direction is cut to a thickness of about 50 mm using a nichrome slicer, and the cut 350 × 450 × 50 mm plate-shaped molded product is broken in half at the center in the longitudinal direction. . Of all the particles present at the fracture surface, the foamed particles themselves calculate the percentage (%) of all the particles broken. The fusion rate of 80% or more is ◎, the fusion rate of less than 60 to 80% is ○, the fusion rate of less than 40 to 60% is △, the fusion rate of less than 40% is X.

Example 1

Tetrabromocyclo in 40 kg of ion-exchanged water containing 0.8 g of sodium dodecylbenzene sulfonate as a dispersant in a 100-liter autoclave as 60 g of tricalcium phosphate (TCP-10, manufactured by Ohira Chemical Co., Ltd.) and a suspension stabilizer (surfactant). 200 g of octane (Pigard FR-200 manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.), 120 g of dicumyl peroxide, 140 g of benzoyl peroxide (75% purity), and 40 kg of styrene monomer dissolved in 30 g of t-butyl peroxybenzoate were mixed. , Dissolved and dispersed under stirring to form a suspension.

Next, under the stirring of 70 rpm, the styrene monomer was polymerized at 90 ° C for 6 hours and further at 110 ° C for 4 hours. 6 g of tricalcium phosphate (TCP-10, manufactured by Ohira Chemical Co., Ltd.) was further added to the suspension at 2 and 3 hours of the 90 ° C. reaction. After the completion of the reaction, the mixture was cooled to room temperature (25 ° C), the contents were taken out from the autoclave, treated in a centrifugation step, and dried to obtain styrene resin particles.

The obtained styrene resin particles were classified into particles of 0.6 to 0.7 mm.

2000 g of water, 9 g of magnesium pyrophosphate, and 0.3 g of sodium dodecylbenzene sulfonate were charged into a 5 L autoclave to obtain an aqueous medium, and 2000 g of the particles were added thereto, followed by stirring at 300 rpm.

Then, the temperature was raised to 95 ° C, 180 g of butane was pressed in while maintaining the temperature, the particles were impregnated with the particles for 3 hours, and then cooled to obtain expandable styrene resin particles. The resulting expandable styrene resin particles were left to age for 4 days at 15 ° C and aged, and then treated in a preliminary foaming step. The conditions of the pre-expanding step were introduced into the pre-expanded foaming styrene resin particles, and pre-expanded using water vapor. By this prefoaming, prefoamed particles having a volume expansion multiple of 50 times were obtained. The cross-sectional SEM photograph (scanning electron microscope) of the obtained prefoamed particle is shown in FIG. From Example 1, it turns out that the prefoamed particle in which the density of foam was suppressed is obtained in Example 1.

In addition, the prefoamed particles are left to mature at room temperature for 24 hours, aged, filled into a well-known steam molding machine for expanded polystyrene, heated with 0.6 kg / cm ² G of steam for 30 seconds, and cooled by water for 20 seconds. A block-like foamed molded product having a foaming multiple of 50 times the foam size of 450 x 100 mm was obtained.

Table 1 shows the flame retardancy, average bubble diameter, and heat sealability of the obtained block-shaped foam molded article.

Example 2

A foamed molded article was obtained in the same manner as in Example 1 except that the tetrabromo cyclooctane amount was 400 g.

Example 3

A foamed molded article was obtained in the same manner as in Example 1 except that the tetrabromo cyclooctane amount was 600 g. The cross-sectional SEM photograph of the obtained prefoamed particle is shown in FIG. From Example 2, it turns out that the prefoamed particle in which the density of foam was suppressed is obtained in Example 3.

Example 4

A foamed molded article was obtained in the same manner as in Example 1 except that the tetrabromo cyclooctane amount was 800 g.

Example 5

A foamed molded article was obtained in the same manner as in Example 2 except that the impregnation temperature was changed to 80 ° C.

Example 6

A foamed molded article was obtained in the same manner as in Example 2 except that the impregnation temperature was changed to 100 ° C.

Example 7

A foamed molded article was obtained in the same manner as in Example 2 except that the impregnation temperature was changed to 110 ° C.

Example 8

A foam molded article was obtained in the same manner as in Example 3 except that no dicumyl peroxide was added.

Example 9

A foamed molded article was obtained in the same manner as in Example 5 except that 2.2 g of α-olefin sulfonate was used instead of sodium dodecylbenzene sulfonate.

Example 10

A foamed molded article was obtained in the same manner as in Example 9 except that the impregnation temperature was 110 ° C.

Example 11

A foam molded article was obtained in the same manner as in Example 2 except that the tricalcium phosphate was changed from TCP-10 manufactured by Ohira Chemical Co., Ltd. to C13-09 manufactured by Budenheim Co., Ltd ..

Example 12

A foamed molded article was obtained in the same manner as in Example 2, except that 85 g of magnesium pyrophosphate was used without using tricalcium phosphate.

Example 13

A foamed molded article was obtained in the same manner as in Example 3, except that 85 g of magnesium pyrophosphate was used without using tricalcium phosphate.

Comparative Example 1

A foamed molded article was obtained in the same manner as in Example 1 except that the tetrabromo cyclooctane amount was 80 g.

Comparative Example 2

A foamed molded article was obtained in the same manner as in Example 1 except that the tetrabromo cyclooctane amount was 160 g.

Comparative Example 3

A foam molded article was obtained in the same manner as in Example 2 except that the impregnation temperature was 115 ° C.

Comparative Example 4

A foamed molded article was obtained in the same manner as in Example 1 except that the tetrabromo cyclooctane amount was 1200 g. The SEM photograph of the cross section of the obtained preexpanded particle | grains is shown in FIG. It can be seen from FIG. 3 that in Comparative Example 4, since the amount of the flame retardant used is large, bubbles are decreasing.

Comparative Example 5

Styrene resin particles were obtained in the same manner as in Example 1 except that tetrabromo cyclooctane was not added. The obtained styrene resin particles were classified into particles of 0.6 to 0.7 mm.

A foamed molded article was obtained in the same manner as in Example 1 except that 10 g of tetrabromo cyclooctane was added to the aqueous medium under stirring at 300 rpm. The SEM photograph of the cross section of the obtained prefoamed particle is shown in FIG. 4 shows that since many flame retardants are present in the surface layer portion, the bubbles in the surface layer portion are small, the bubbles in the center are large, and the bubbles are dense.

Comparative Example 6

A foamed molded article was obtained in the same manner as in Example 1 except that 30 g of tetrabromo cyclooctane was added to the aqueous medium under stirring at 300 rpm. The cross-sectional SEM photograph of the obtained prefoamed particle is shown in FIG. 5 shows that since many flame retardants are present in the surface layer portion, bubbles in the surface layer portion are small, bubbles in the center are large, and denseness is generated in the bubbles.

Table 1 shows the flame retardancy, average bubble diameter, and heat sealability of the block-shaped foamed molded articles obtained in Examples 2 to 13 and Comparative Examples 1 to 6.

TBCO Department Dispersant Surfactants Impregnation temperature
℃ Molecular Weight
M _W Flame retardant
second Average bubble diameter
Μm Heat
Adhesion Example One 0.5 TCP-10 Dodecylbenzene Sodium Sulfonate 95 265000 1.7 pass 280 ◎ 2 1.0 TCP-10 Dodecylbenzene Sodium Sulfonate 95 256000 1.1 pass 290 ◎ 3 1.5 TCP-10 Dodecylbenzene Sodium Sulfonate 95 246000 0.3 pass 170 ○ 4 2.0 TCP-10 Dodecylbenzene Sodium Sulfonate 95 228000 0.3 pass 180 ○ 5 1.0 TCP-10 Dodecylbenzene Sodium Sulfonate 80 268000 0.6 pass 340 ◎ 6 1.0 TCP-10 Dodecylbenzene Sodium Sulfonate 100 247000 0.9 pass 180 ○ 7 1.0 TCP-10 Dodecylbenzene Sodium Sulfonate 110 241000 1.0 pass 73 ○ 8 1.5 TCP-10 Dodecylbenzene Sodium Sulfonate 95 252000 0.6 pass 210 ○ 9 1.0 TCP-10 α-olefin sulfonates 90 239000 0.5 pass 190 ○ 10 1.0 TCP-10 α-olefin sulfonates 110 237000 0.3 pass 110 ○ 11 1.0 C13-09 Dodecylbenzene Sodium Sulfonate 95 252000 0.6 pass 220 ○ 12 1.0 Pyrophosphate Mg Dodecylbenzene Sodium Sulfonate 95 248000 0.4 pass 270 ◎ 13 1.5 Pyrophosphate Mg Dodecylbenzene Sodium Sulfonate 95 251000 0.3 pass 250 ○ Comparative example One 0.2 TCP-10 Dodecylbenzene Sodium Sulfonate 95 283000 Combustion fail 450 ◎ 2 0.4 TCP-10 Dodecylbenzene Sodium Sulfonate 95 281000 3.7 fail 350 ◎ 3 1.0 TCP-10 Dodecylbenzene Sodium Sulfonate 115 223000 1.3 pass 41 × 4 3.0 TCP-10 Dodecylbenzene Sodium Sulfonate 95 191000 0.3 pass 35 × 5 0.5 TCP-10 Dodecylbenzene Sodium Sulfonate 95 262000 3.3 fail 320 ○ 6 1.5 TCP-10 Dodecylbenzene Sodium Sulfonate 95 224000 0.8 pass 150 ×

From the above Table 1, when the specific flame retardant is used in a specific amount, and the impregnation temperature of the physical foaming agent is foamed, the foamed styrene resin particles can be obtained a foamed molded article having excellent thermal fusion properties and excellent flame retardancy between particles. It can be seen that can provide.

The tetracyclo bromooctane content rate of the surface layer part and the whole particle | grain of the expandable styrene resin particle obtained in Examples 1-13 and Comparative Examples 1-6 was measured with the following method, and the result was described in Table 1.

(Tetracyclo bromooctane content rate measuring method)

The surface part of 50 times foamed molded article is sliced by thickness 0.2mm, length 20cm, and width 20cm with the slicer (FK-4N by Fujishima Koki company), and this is treated as a flame-retardant foamable styrene resin particle surface layer part. The tetracyclo bromooctane content rate of the sliced surface part is measured. The tetracyclo bromooctane content rate is measured by an order analysis method (thin film method) using a fluorescence X-ray analyzer (RIX-2100 manufactured by Rigaku Co., Ltd.). That is, 2-3 g of the sliced surface portion is hot pressed at 200 to 230 ° C. to produce a film having a thickness of 0.1 to 1 mm, a length of 5 cm, and a width of 5 cm. After measuring the weight of the film, calculating the basis weight and to balance the component as C ₈ H _8, and calculates the order analysis by the amount Br in the X-ray intensity. Since the ratio of Br contained in tetrabromo cyclooctane is 75%, the amount of tetrabromo cyclooctane in a film is computed from the amount of Br obtained. The calculation result is taken as the tetracyclo bromooctane content rate contained in the surface layer part of a flame-retardant foamable styrene resin particle.

The tetrabromo cyclooctane content rate contained in the flame-retardant foamable styrene resin whole particle | grains is made to be the same as the preparation amount at the time of tetrabromo cyclooctane impregnation.

Table 2 shows the ratio of the tetracyclo bromooctane content rate contained in the surface layer part of a flame-retardant foamable styrene resin particle, the whole, and the tetracyclo bromooctane content rate contained in the surface layer part with respect to the tetracyclo bromooctane content rate contained in the whole.

Overall TBCO content b
(wt%) Superficial
TBCO content a
(wt%) Of TBCO content
Surface layer / total ratio b × 1.1 Example 1 0.50 0.49 0.98 0.55 Example 2 1.00 1.01 1.01 1.1 Example 3 1.50 1.52 1.01 1.65 Example 4 2.00 2.01 1.01 2.2 Example 5 1.00 0.99 0.99 1.1 Example 6 1.00 1.03 1.03 1.1 Example 7 1.00 1.01 1.01 1.1 Example 8 1.50 1.50 1.00 1.65 Example 9 1.00 1.01 1.01 1.1 Example 10 1.00 1.00 1.00 1.1 Example 11 1.00 1.00 1.00 1.1 Example 12 1.00 0.99 0.99 1.1 Example 13 1.50 1.55 1.03 1.65 Comparative Example 1 0.20 0.20 1.00 0.22 Comparative Example 2 0.40 0.41 1.01 0.44 Comparative Example 3 1.00 1.01 1.01 1.1 Comparative Example 4 3.00 2.95 0.98 3.3 Comparative Example 5 0.50 0.56 1.12 0.55 Comparative Example 6 1.50 1.71 1.14 1.65

It is understood from Table 2 that in the examples satisfying the formula a ≦ 1.1 × b, foamable styrene resin particles capable of providing a foamed molded article having excellent flame resistance and excellent flame resistance when foamed can be obtained can be provided. Can be. On the other hand, it is understood that Comparative Examples 5 and 6, which are not satisfactory, are inferior in thermal fusion and / or flame retardancy of the foamed molded article.

Claims

In suspension polymerization of a styrene monomer to obtain styrene resin particles, 0.45 to 2.0 parts by weight of tetrabromo cyclooctane is added to 100 parts by weight of the styrene monomer, and then during suspension polymerization of the styrene monomer. Or the method of manufacturing a flame-retardant foamable styrene resin particle which obtains a flame-retardant foamable styrene resin particle by impregnating the styrene resin particle after adjusting suspension impregnation temperature to 80-110 degreeC after a suspension polymerization.

The method according to claim 1,
A method for producing a flame retardant foamable styrene resin particle wherein the suspension polymerization is carried out in the presence of a surfactant.

The method according to claim 1,
A method for producing a flame retardant foamable styrene resin particle further comprising a flame retardant aid in the styrene monomer.

The method according to claim 3,
The flame retardant aid is a method for producing a flame retardant foamable styrene resin particle selected from cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane.

The method according to claim 3 or 4,
A method for producing a flame retardant foamable styrene resin particle wherein the flame retardant aid is used in an amount of 0.1 to 0.5 parts by weight based on 100 parts by weight of a styrene monomer.

The method according to any one of claims 1 to 5,
The impregnation temperature is a method for producing a flame-retardant foamable styrene resin particles is adjusted so that the foamed molded product of the foaming multiple 50 times obtained by foaming the flame-retardant foamable styrene resin particles have an average bubble diameter of 50 ~ 350㎛.

The method according to any one of claims 1 to 6,
A method for producing a flame retardant foamable styrene resin particle wherein the styrene monomer is selected from styrene, α-methyl styrene, paramethyl styrene, t-butyl styrene, and crawl styrene.

Equipped with styrene resin particles and the physical blowing agent and tetrabromo cyclooctane contained in the styrene resin particles,
The tetrabromo cyclooctane is contained in the surface layer portion of the styrene resin particles, and the tetrabromo cyclooctane content is a (% by weight), and the tetrabromo cyclooctane content is contained in the entirety of the styrene resin particles. Weight%), the styrene-based resin particles are contained in the styrene resin particles so as to satisfy the relationship
The tetrabromo cyclooctane content rate contained in the said whole styrene resin particle is 0.45-2.00 weight part with respect to 100 weight part of styrene resin particles,
A flame-retardant foamable styrene resin particle which provides a foam having an average bubble diameter of 50 to 350 µm when foamed at a foaming multiple of 50 times.