JP2013082932A - Foamed molding of flame-retardant expandable styrenic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foamed molding of a flame-retardant expandable styrenic resin, which can be recycled, and has high flame retardancy and thermal stability with a small addition amount of a bromine-containing organic compound-based flame retardant.SOLUTION: The foamed molding is obtained by extrusion-foaming a flame-retardant expandable styrenic resin composition containing (A) a styrenic resin, (B) a bromine-containing organic compound, and (F) a foaming agent. The bromine-containing organic compound (B) is a mixture of (a) a bromine-containing organic compound having a 2,3-dibromopropyl group and (b) a bromine-containing organic compound having 2,3-dibromo-2-alkylpropyl group. The bromine-containing organic compound (B) is contained in an amount of 0.5 to 10 pts.wt. per 100 pts.wt. of the styrenic resin (A).

Description

  The present invention relates to a flame-retardant foamed styrene resin composition and a foamed molded product thereof.

  Since the styrene resin foam is lightweight, it is used in various fields such as heat insulation applications such as home appliances and building materials and civil engineering applications such as embankment methods.

  Styrenic resin is made of only carbon and hydrogen, and once ignited, it emits black smoke and burns violently. Therefore, depending on the application, it is necessary to add a flame retardant to make it flame retardant. As such a flame retardant, bromine-containing compounds are widely used, and in order to impart high flame retardancy with a small addition amount, all bromine atoms such as hexabromocyclododecane (HBCD) are aliphatic carbon. Although flame retardants bonded to the flame retardant are effective, these flame retardants have low thermal stability and cause problems such as deterioration of the resin, coloring of the resin, and corrosion of the apparatus due to generation of hydrogen bromide gas.

  On the other hand, tetrabromobisphenol-A-bis (2,3-dibromopropyl ether) is also known as a flame retardant having excellent thermal stability, but these are flame retardant compared to flame retardants such as HBCD. Since the effect is low, it is necessary to greatly increase the amount of addition. Therefore, there is a problem that not only the physical properties of the styrene resin foam deteriorate, but also the cost of the styrene resin foam increases significantly.

  Styrenic resin foams are manufactured through the steps of heat melting, adding a foaming agent, cooling, and extrusion foaming under low pressure conditions. However, in the styrene resin foam using a flame retardant having poor thermal stability such as the HBCD, the molecular weight of the styrene resin is reduced or coloring occurs. Therefore, as a method for solving this, it has been reported that various heat stabilizers are used in combination (for example, JP-A-2006-316251), and a styrene resin foam using these flame retardants can be produced. It became so.

  By the way, in recent years, it has been required to use a used styrene resin foam again as a raw material due to an increase in environmental awareness. In the production of such a regenerated styrene resin foam, since the styrene resin foam that has already undergone the heat-melting process at the time of the previous production is used by further heat-melting, more thermal stability than ever is required, Sufficient thermal stability cannot be obtained only by using the thermal stabilizer alone.

  Therefore, in JP-A-2005-139356, tetrabromobisphenol A-bis (2-methylallyl ether) or tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether) is used as a flame retardant. Describes that a styrene resin foam excellent in recyclability can be obtained. However, it has been found that these styrenic resin foams do not have sufficient thermal stability.

JP 2006-316251 A JP 2005-139356 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a foamed styrene resin composition that is excellent in flame retardancy and thermal stability and is suitable for recycling.

The present invention includes (A) a styrenic resin, (B) a bromine-containing organic compound, and (F) a blowing agent.
The bromine-containing organic compound (B) is a mixture of (a) a bromine-containing organic compound having a 2,3-dibromopropyl group and (b) a bromine-containing organic compound having a 2,3-dibromo-2-alkylpropyl group A flame retardant foamed styrene resin composition characterized by containing 0.5 to 10 parts by weight of a bromine-containing organic compound (B) per 100 parts by weight of the styrene resin (A).

  According to the present invention, by using together a bromine-containing organic compound having a 2,3-dibromopropyl group and a bromine-containing organic compound having a 2,3-dibromo-2-alkylpropyl group as a flame retardant, the total is small. A foamed styrenic resin having high flame retardancy in addition amount and high thermal stability that can be recycled can be obtained.

  The (A) styrene resin of the present invention is, for example, a styrene homopolymer, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, pt -Butyl styrene, α-methyl styrene, α-methyl-p-methyl styrene, 1,1-diphenylethylene, p- (N, N-diethylaminoethyl) styrene, p- (N, N-diethylaminomethyl) styrene and the like And a mixture thereof, preferably those containing 50% by weight or more of styrene monomer, typically polystyrene.

  Furthermore, you may mix | blend a rubber-like polymer with the said styrene resin. Examples of the rubber-like polymer include polybutadiene, polyisoprene, styrene-butadiene copolymer, styrene-isoprene copolymer, acrylonitrile-butadiene copolymer, styrene-isobutylene-butadiene copolymer, and butadiene- (meth) acryl. Acid ester copolymer, styrene-butadiene block copolymer, styrene-isoprene block copolymer, butyl rubber, ethylene-α-olefin copolymer (ethylene-propylene rubber), ethylene-α-olefin-polyene copolymer (Ethylene-propylene-diene rubber), silicone rubber, acrylic rubber, hydrogenated diene rubber (hydrogenated styrene-butadiene block copolymer, hydrogenated butadiene polymer, etc.) and the like. These rubbery polymers can be used alone or in admixture of two or more. The amount used is preferably 30% by weight or less, more preferably 20% by weight or less in the monomer component.

  The (B) bromine-containing organic compound of the present invention includes B (a), a bromine-containing organic compound having a 2,3-dibromopropyl structure, and a B (b) 2,3-dibromo-2-alkylpropyl structure. And a bromine organic compound.

  Examples of the bromine-containing organic compound B (a) of the present invention include tetrabromobisphenol-A-bis (2,3-dibromopropyl ether), tetrabromobisphenol-S-bis (2,3-dibromopropyl ether), tetra Examples thereof include bromobisphenol-F-bis (2,3-dibromopropyl ether), tris (2,3-dibromopropyl) isocyanurate and tris (2,3-dibromopropyl) cyanurate.

  The bromine-containing organic compound B (b) of the present invention has a 2,3-dibromo-2-alkylpropyl structure. Examples of such a bromine-containing organic compound B (b) include tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-S-bis (2,3-dibromo). 2-methylpropyl ether), tetrabromobisphenol-F-bis (2,3-dibromo-2-methylpropyl ether) and the like.

  The blending ratio of the bromine-containing organic compound B (a) and the bromine-containing organic compound B (b) is preferably 10/90 to 90/10, and 20/80 to 80/20, based on weight. It is more preferable, and it is still more preferable that it is 30 / 70-80 / 20. By setting it within the above range, higher thermal stability can be imparted.

  The flame-retardant styrene resin foam composition of the present invention contains 0.5 to 10 parts by weight of (B) a bromine-containing organic compound per 100 parts by weight of (A) styrene resin on a weight basis. And preferably 0.5 to 6 parts by weight. By setting it within the above range, high flame retardancy and high thermal stability can be imparted.

  The flame retardant styrene resin foam composition of the present invention may further contain (C) a heat stabilizer. (C) Thermal stability can be further improved by blending a thermal stabilizer. Examples of such (C) heat stabilizer include phosphite compounds, thioether compounds, hindered phenol compounds, and the like.

  Examples of the phosphite compound include tris (2,4-di-t-butylphenyl) phosphite, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, bis [2,4-bis (1,1-Dimethylethyl) -6-methylphenyl] ethyl ester phosphorous acid, tetrakis (2,4-di-t-butylphenyl) [1,1-biphenyl] -4,4′-diylbisphospho Knight, bis (nonylphenyl) pentaerythritol diphosphite, bisstearyl pentaerythritol diphosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, 2,2'-methylenebis (4,6-di-t-butyl-1-phenyloxy) (2-ethylhexyloxy) phosphorus, tetra (tridecyl)- , 4'-Butylidene-bis (2-t-butyl-5-methylphenyl) diphosphite, hexatridecyl-1,1,3-tris (3-t-butyl-6-methyl-4-oxyphenyl) -3 -Methylpropane triphosphite, mono (dinonylphenyl) mono-p-nonylphenyl phosphite, tris (monononylphenyl) phosphite, tetraalkyl (C = 12-16) -4,4'-isopropylidene- (bis Phenyl) diphosphite, phosphorous mono- or diphenyl mono- or dialkyl (or alkoxyalkyl, C = 8-13), diphenylisodecyl phosphite, trisdecyl phosphite, triphenyl phosphite and the like.

  Examples of the thioether compound include dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, pentaerythritol tetrakis (3 -Laurylthiopropionate), ditridecyl-3,3'-thiodipropionate, 2-mercaptobenzimidazole and the like.

  Examples of the hindered phenol compound include 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3- t-butyl-5-methyl-4-hydroxyphenyl) propionate], glycerol tris [3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate], pentaerythritol tetrakis [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, thiodiethylenebis [3- (3,5-di -T-butyl-4-hydroxyphenyl) propionate], N, N′-hexane-1,6-diylbis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionamide], 2,4-dimethyl-6- (1-methylpentadecyl) phenol, diethyl [[3,5-bis (1,1 -Dimethylethyl) -4-hydroxyphenyl] methyl] phosphonate, calcium diethylbis [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] phosphonate, 3,3 ', 3 ", 5,5 ′, 5 ″ -hexa-t-butyl-a, a ′, a ″-(mesitylene-2,4,6-triyl) tri-p-cresol, 4,6-bis (octylthiomethyl)- o-cresol, ethylenebis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate], hexamethylenebis [3- (3,5-di-tert-butyl) -4-hydroxyphenyl) propionate], 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6 (1H, 3H , 5H) -trione, 1,3,5-tris [(4-tert-butyl-3-hydroxy-2,6-xylyl) methyl] -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 2,6-di-t-butyl-4- (4,6-bis (octylthio) -1,3,5-triazin-2-ylamino) phenol, and the like.

  (C) It is preferable that the addition amount in the case of using a heat stabilizer is 0.01-0.5 weight part per 100 weight part of (A) styrene resin.

  In addition, the flame retardant styrene resin foam composition of the present invention may further contain (D) a flame retardant aid. (D) By mix | blending a flame retardant adjuvant, the flame retardant effect of (B) a bromine containing organic compound can be improved more. Examples of such flame retardant aid (D) include antimony trioxide, antimony pentoxide, zinc borate, hydrated aluminum oxide, molybdenum oxide and the like. (D) It is preferable that the addition amount in the case of using a flame retardant aid is 0.01 to 5 parts by weight per 100 parts by weight of (A) styrene resin.

  It is known that the flame retardant effect of a brominated flame retardant is enhanced by (E) a radical generator or a phthalocyanine metal complex. Examples of such radical generators are cumene peroxide, cumene hydroperoxide, di-t-butyl peroxide, di-t-hexyl peroxide, 2,5-dimethyl-2,5-di (t-butyl). Peroxy) -hexyne-3, dicumyl peroxide, 2,3-dimethyl-2,3-diphenylbutane, and examples of phthalocyanine metal complexes include phthalocyanine iron, phthalocyanine manganese, phthalocyanine cobalt, and the like. Dicumyl peroxide, 2,3-dimethyl-2,3-diphenylbutane and iron phthalocyanine are preferred.

  The flame retardant foamed styrene resin composition of the present invention can be formed into a foamed molded article by extrusion foaming or bead foaming. In the case of the extrusion foaming method, the brominated flame retardant (B) and other additives are melt-mixed in the extruder with the styrene resin (A), and after the foaming agent (F) is press-fitted into the atmosphere from the extruder die. Foam molding is performed by extrusion. In the case of the bead foaming method, styrene resin beads obtained by suspension polymerization are impregnated with an emulsified dispersion of other additives except brominated flame retardant (B) and foaming agent (F), and then in an autoclave. The beads obtained by press-fitting and impregnating a foaming agent and separating water are pre-foamed with water vapor at 100 ° C., and then molded by heating and foaming with hot pressurized steam in a mold.

  Here, as the blowing agent (F), for example, propane, butane, isobutane, pentane, cyclopentane, hexane, cyclohexane, 1-chloro-1,1-difluoroethane, monochlorodifluoromethane, monochloro-1,2,2, 2-tetrafluoroethane, 1,1-difluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,3,3,3-pentafluoropropane, dichloromethane, 1,2-dichloroethane, dimethyl ether, diethyl ether And volatile organic foaming agents such as ethyl methyl ether, inorganic foaming agents such as water, nitrogen and carbon dioxide, and chemical foaming agents such as azo compounds. These can be used alone or in combination of two or more. The blending amount of the foaming agent (F) is not limited because it varies depending on the required foam performance and molding method, but preferably 0.01 to 0.5 moles with respect to 100 parts by weight of the polystyrene resin, More preferably, it is 0.05-0.3 mol.

  Moreover, when manufacturing the flame-retardant styrene-type resin foam molding of this invention, in addition to a foaming agent (F), a foaming nucleating agent can also be mix | blended. Examples of such a foam nucleating agent include talc, bentonite, kaolin, mica, silica, clay, diatomaceous earth, and the like. When the foam nucleating agent is used, the amount used is preferably 0.01 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the polystyrene resin.

  In the flame-retardant foamed styrene resin composition of the present invention, a bromine-containing organic compound other than (B (a)) and (B (b)), phosphate ester, Silicone compounds and hydrated metal compounds may be used in combination.

  In addition, the flame retardant foamed styrene resin composition of the present invention includes a light stabilizer, an ultraviolet absorber, an ultraviolet stabilizer, a heavy metal deactivator, and an impact modifier within a range not impairing the effects of the present invention. In addition, known resin additives such as colorants, lubricants, anti-dripping agents, crystal nucleating agents, antistatic agents and compatibilizers can be blended.

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited thereto.
The raw materials used in Examples and Comparative Examples are as follows.
(A) Styrenic resin (A1)
GP-PS; PSJ polystyrene G9305 (manufactured by PS Japan Co., Ltd.)
(A2)
Styrene resin beads (produced by the following method)
Into a 5L autoclave with a stirrer, 2000g of ion-exchanged water, 4g of tricalcium phosphate and 0.5g of sodium laurylbenzenesulfonate were charged, and 6g of benzoyl peroxide (BPO) previously dissolved as a catalyst was stirred while stirring. In addition to 2000 g of monomer, suspension polymerization was carried out at 100 ° C. for 8 hours. The obtained polystyrene resin beads are separated by filtration, washed with distilled water, dried, further classified with a sieve, and sorted into a particle size range of 0.3 to 1.0 mm to obtain styrene resin beads (A2 ) The weight average molecular weight (Mw) in GPC analysis was 290,000.
(B) Bromine-containing organic compound (B (a) -1)
Tetrabromobisphenol-A-bis (2,3-dibromopropyl) ether; Pyroguard SR-720 (Daiichi Kogyo Seiyaku Co., Ltd.)
(B (a) -2)
Tetrabromobisphenol-S-bis (2,3-dibromopropyl) ether; Nonene PR-2 (manufactured by Maruhishi Oil Chemical Co., Ltd.)
(B (a) -3)
Tris (2,3-dibromopropyl) isocyanurate; TAIC-6B (manufactured by Nippon Kasei Co., Ltd.)
(B (b) -1)
Tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl) ether; Pyroguard SR-130 (Daiichi Kogyo Seiyaku Co., Ltd.)
(C) Thermal stabilizer Mixture of tris (2,4-di-t-butylphenyl) phosphite and pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]; IRGANOX B 225 (Ciba Specialty Chemicals Co., Ltd.)
(E) Flame retardant enhancer 2,3-dimethyl-2,3-diphenylbutane; NOFMER BC-90 (manufactured by NOF Corporation)
(F) Foaming agent Isobutane (foaming nucleating agent)
Talc MS (Nippon Talc Industry Co., Ltd.)
(Additive)
(Additive 1)
Dioctyl adipate; DOA (manufactured by Daihachi Chemical Co., Ltd.)
<Test specimen preparation method>
(Extruded foam molding)
The raw materials shown in Tables 1 and 2 except for the foaming agent are charged into an extruder having a diameter of 65 mm of a two-stage extruder connected in series from a diameter of 65 mm to a diameter of 90 mm, and heated to 200 ° C. to be melted, plasticized, and kneaded. By doing so, a styrene resin composition was obtained. Subsequently, a predetermined amount of foaming agent is press-fitted in a separate line at the tip of the 65 mm extruder (opposite to the die of the 90 mm diameter extruder), and the resin temperature is cooled to 120 ° C. with a 90 mm diameter extruder, and the diameter is 90 mm. An extruded foam molded body of a rectangular parallelepiped styrenic resin was obtained by extruding into the atmosphere from a die lip having a rectangular cross section with a thickness direction of 2.5 mm and a width direction of 45 mm provided at the tip of the extruder.
(Bead method foam molding)
In an autoclave equipped with a stirrer, 100 parts by weight of distilled water and the raw materials listed in Table 3 excluding styrene resin beads and a foaming agent are charged with a predetermined amount of a heat stabilizer and a compounding agent, and stirred at room temperature to be blended. After emulsifying and dispersing the agent, 100 g of classified polystyrene resin beads were added, and stirring was continued at a temperature of 100 ° C. for 5 hours to impregnate the compounding agent. 10 g of a foaming agent was injected into this and impregnated with the foaming agent at 115 ° C. for 8 hours. Polystyrene resin beads obtained by separating water are heated with steam at 100 ° C. and pre-foamed, and then the foam is placed in a mold and heat-fused with pressurized steam at 115 ° C. to form a cubic shape. A foamed molded product was obtained.
The foamed molded product was evaluated by the following method.
<Moldability>
The state of the foamed molded product was visually evaluated as follows.
A: A good foam was stably obtained without cracks, cracks and voids.
X: Gas is ejected from the die, and a foam cannot be obtained stably. Further, the foam had cracks, cracks, voids and the like.
<Flame retardance>
The oxygen index was measured according to JIS K-7201.
○: Oxygen index is 26 or more ×: Oxygen index is less than 26 <Molecular weight reduction rate>
The molecular weights of the styrene resin before foam molding and the flame retardant styrene resin foam molding were measured by GPC analysis, and the reduction rate (%) of the weight average molecular weight (Mw) before and after molding of the polystyrene resin was calculated.
<Recyclability>
In Example 8, Comparative Example 10 and Comparative Example 11, reheating was performed assuming recyclability, and the molecular weight reduction of the polystyrene resin was determined.
The cube formed in the example was sliced with a cutter to form a board, and the board was compressed with a biaxial roll and then roughly crushed with a pulverizer. The roughly crushed recovered resin was put into a lab plast mill, kneaded at 200 ° C., taken out after 5 minutes, cooled, and subjected to GPC analysis to obtain a weight average molecular weight, and a reduction rate of the molecular weight was calculated.
○: Retention rate of weight average molecular weight is 70% or more ×: Retention rate of weight average molecular weight is less than 70%

As is clear from Table 1, it can be seen that the extruded foamed articles of Examples 1 to 7 are excellent in any of the items of moldability, flame retardancy, and thermal stability.
On the other hand, as in Comparative Examples 1 to 6 described in Table 2, an extruded foam molded body using only one kind of bromine-containing organic compound can satisfy the flame retardancy, moldability, and thermal stability. I couldn't. Moreover, even when two kinds of bromine-containing organic compounds having no 2,3-dibromo-2-alkylpropyl structure are used in combination as in Comparative Examples 7 to 9, all of flame retardancy, moldability, and thermal stability are satisfied. I didn't get anything to do.

As is clear from Table 3, it can be seen that the bead-method foamed molded article of Example 8 is excellent in all items of moldability, flame retardancy, and thermal stability.
On the other hand, as in Comparative Examples 10 and 11, in the bead method foamed molding using only one kind of bromine-containing organic compound, those satisfying all of the flame stability, moldability, and thermal stability assuming recycling are obtained. I couldn't.

  The foamed styrene resin foam composition of the present invention can provide a styrene resin foam having high flame retardancy and high thermal stability suitable for recycling even if the amount of flame retardant added is small. it can. Therefore, it can be used for various applications including heat insulation applications such as home appliances and building materials and civil engineering applications such as embankment methods.

Claims (4)

A foam molded article obtained by extrusion foaming a flame retardant foamed styrene resin composition containing (A) a styrene resin, (B) a bromine-containing organic compound and (F) a foaming agent,
Bromine-containing organic compound (B)
(A) a mixture of a bromine-containing organic compound having a 2,3-dibromopropyl group and (b) a bromine-containing organic compound having a 2,3-dibromo-2-alkylpropyl group,
A flame-retardant foamed styrene-based resin foam molded article comprising 0.5 to 10 parts by weight of a bromine-containing organic compound (B) per 100 parts by weight of a styrene-based resin (A).   The bromine-containing organic compound (B) a is tetrabromobisphenol A, tetrabromobisphenol S or tetrabromobisphenol F bis (2,3-dibromopropyl) ether, tris (2,3-dibromopropyl) isocyanurate, or The flame-retardant foamed styrene resin foam molded article according to claim 1, selected from tris (2,3-dibromopropyl) cyanurate.   The flame retardant according to claim 1, wherein the bromine-containing organic compound (B) b is selected from bis (2,3-dibromo-2-methylpropyl) ether of tetrabromobisphenol A, tetrabromobisphenol B or tetrabromobisphenol F. Foamed styrenic resin foam.   4. The flame-retardant foam according to claim 1, wherein the ratio of (B) a / (B) b in the bromine-containing organic compound (B) is 10/90 to 90/10 on a weight basis. Styrenic resin foam molding.