KR20090028644A - Flame retardant extruded polystyrene foam compositions - Google Patents

Abstract

Extrudable polystyrene foam compositions having flame retardant properties, flame retardant extruded polystyrene foams, methods of making such foams, and products comprising such compositions and foams are provided. A flame-retarded extruded polystyrene foam contains a flame retardant compound having the structure.: Formula (I)

Description

Flame retardant extruded polystyrene foam composition {FLAME RETARDANT EXTRUDED POLYSTYRENE FOAM COMPOSITIONS}

The present invention relates to a flame retardant composition and an extruded polystyrene foam formed therefrom.

Styrene polymer compositions and foams, such as extruded polystyrene foam, are widely used in the manufacture of molded articles, paints, film coatings, and sundries. Extruded polystyrene foam is characterized by a fully closed cell that provides good insulation and high compressive strength.

Extruded polystyrene foam is typically prepared by combining a styrene polymer, a flame retardant compound and a blowing agent and extruding the resulting mixture through a die to form a foam. When used as an insulating material, it is important to avoid forming spaces or air passages in the cell structure.

For some product applications, it may be desirable to reduce the flammability of such compositions and foams. Flame retardant compounds for use in extruded polystyrene foams require several requirements including thermal stability, significant miscibility in polystyrene, and high flame retardancy. Flame retardant compounds should also not interfere with the foaming process. For example, if brominated flame retardants exhibit off-gassing of HBr due to flame retardant decomposition, it may be difficult to maintain a consistently closed cell structure. Therefore, the flame retardant should exhibit low thermal HBr release under extrusion and foaming conditions. Moreover, significant HBr gas emissions due to flame retardant decomposition can reduce the molecular weight of polystyrene. While not wishing to be bound by theory, it is believed that HBr forms bromine radicals that cause the cleavage of polystyrene chains.

It has been proposed to use halogenated flame retardant compounds in various polymers. For example, US Pat. No. 3,784,509, each of which is incorporated by reference in its entirety; 3,868,388; 3,868,388; 3,903,109; 3,903,109; 3,915,930; And 3,953,397. The compound is typically aliphatic, cycloaliphatic or aromatic. Aliphatic halogenated compounds are known to be more efficient because they break more easily. At the same time, the compounds are less resistant to temperature than aromatic halogenated flame retardants. Therefore, the use of aliphatic halogenated flame retardants is often limited only to very low processing temperatures. Mack, AG, Kirk Othmer Chemical Encyclopedia, Flame Retardants , Halogenated Section 4 , Online Posting Date: September 17, 2004. However, whether a compound is suitable for a given use depends on the polymer and the method of blending. Troitzsch, JH, Overview of Flame Retardants: Fire and Fire Safety, Markets and Applications, Mode of Action and Main Families, Role in Fire Gases and Residues, Chimica Ogi / Chemistry Today , Vol. 16, Jan / Feb 1998].

Despite the limitations associated with aliphatic and cycloaliphatic brominated compounds, it may be desirable to use such compounds. Unlike many aromatic brominated compounds that are too hard to decompose at the desired temperature, aliphatic and cycloaliphatic brominated compounds are effective at the desired temperature. In addition, polymer foams typically cannot withstand the high loads required to achieve the desired effect.

Accordingly, there is a need for flame retardant compounds containing aliphatic and / or cycloaliphatic bromines suitable for use in extruded polystyrene foams that achieve the desired efficacy at high processing temperatures without adversely affecting the polystyrene or the resulting foam.

There is a need for flame retardant compounds containing aliphatic and / or cycloaliphatic bromines suitable for use in extruded polystyrene foams that achieve the desired efficacy at high processing temperatures without adversely affecting the polystyrene or the resulting foams.

The present invention relates generally to flame retardant extruded polystyrene foam. According to one aspect of the invention, the polystyrene foam contains a flame retardant compound having the structure:

In one aspect of the invention, the flame retardant compound is present in an amount from about 0.1 to about 10 weight percent of the foam. In another aspect, the flame retardant compound is present in an amount of about 0.5 to about 7 weight percent of the foam. In another aspect, the flame retardant compound is present in an amount of about 1 to about 5 weight percent of the foam. In yet another aspect, the flame retardant compound is present in an amount from about 3 to about 4 weight percent of the foam.

The foam may be formed from a composition in which the initial shear viscosity decreases to less than about 15% after about 32 minutes at 19O <0> C. In one aspect, the foam may be formed from a composition where the initial shear viscosity decreases to less than about 10% after about 32 minutes at 175 ° C.

The foam may be formed from a composition wherein the molecular weight (M _w ) of the polystyrene is at least about 90% of the polystyrene in the same composition without the flame retardant compound. In another aspect, the foam may be formed from a composition wherein the molecular weight (M _w ) of the polystyrene is at least about 95% of the polystyrene in the same composition without the flame retardant compound.

The foam may have a ΔE of about 1 to about 3 as compared to the same polystyrene foam that does not contain a flame retardant compound. In another aspect, the foam may have a ΔE of about 1 as compared to the same polystyrene that does not contain a flame retardant compound.

Extruded polystyrene foam can be used to form articles of manufacture. For example, extruded polystyrene foam can be used to form thermal insulation.

According to another aspect of the invention, the flame retardant extruded polystyrene foam contains a flame retardant compound, wherein the foam has one or more of the following features:

(a) the foam is formed from a composition in which the initial shear viscosity decreases to less than about 15% after about 32 minutes at 19O <0> C;

(b) the foam is formed from a composition in which the initial shear viscosity decreases to less than about 10% after about 32 minutes at 175 ° C .;

(c) the foam is formed from a composition wherein the molecular weight (M _w ) of the polystyrene is at least about 90% of the polystyrene in the same composition without the flame retardant compound; or

(d) The foam has a ΔE of about 1 to about 3 when compared to the same polystyrene foam containing no flame retardant compound.

The flame retardant compound may be an aliphatic brominated compound, an alicyclic compound or a combination thereof. For example, the flame retardant compound can be:

.

.

The present invention also contemplated an extruded polystyrene foam containing a flame retardant compound having the following structure, wherein the foam is substantially free of antimony trioxide:

.

.

The present invention further contemplated a process for preparing a flame retardant extruded polystyrene foam that is substantially free of antimony trioxide, the process comprising providing a molten polystyrene resin, from about 0.1% to about 10% by weight of a flame retardant compound having the structure Melt blending with molten polystyrene, adding a blowing agent to the molten polystyrene to form a flame retardant polystyrene composition and extruding the flame retardant polystyrene composition through a die:

.

.

Detailed description of the invention

The present invention generally relates to extrudable polystyrene foam compositions having flame retardancy, flame retardant extruded polystyrene foam, methods of making the foam, and articles comprising the composition and foam. According to one aspect of the invention, the flame retardant extruded polystyrene foam composition comprises polystyrene and one or more flame retardant compounds. Optionally, the composition may comprise one or more synergists, stabilizers, or various other additives.

Flame retardant compounds of the invention are compounds having the following structure, tautomers, stereoisomers, and polymorphs thereof (collectively referred to as "compound (I)"):

.

.

It has been found that the use of compound (I) to form a flame retardant composition results in a thermally stable and effective polystyrene foam. Compound (I) is easily melt blended into a molten polystyrene resin to form a flame retardant composition. Unlike other compounds that are easy to decompose during processing and degrade foam quality, compound (I) is stable during processing and does not adversely affect the formation of polystyrene foam.

According to one aspect of the invention, the flame retardant composition has an initial shear viscosity that decreases to less than about 15% after about 32 minutes at 19O &lt; 0 &gt; C. In another aspect, the foam may be formed from a composition where the initial shear viscosity decreases to less than about 10% after about 32 minutes at 175 ° C.

The foam may be formed from a composition wherein the molecular weight (M _w ) of the polystyrene is at least about 90% of the polystyrene in the same composition without the flame retardant compound. In one aspect, the foam is formed from a composition wherein the molecular weight (M _w ) of the polystyrene is at least about 95% of the polystyrene in the same composition without the flame retardant compound.

In addition, the color of the foam does not change significantly due to the presence of the flame retardant compound (I). When compared to polymers without flame retardant compounds, the foam may have a ΔE of about 0 to about 10. In one aspect, the foam has a ΔE of about 0 to about 5. In another aspect, the foam has a ΔE of about 0 to about 3. In another aspect, the foam has a ΔE of about 1 to about 3. In another aspect the foam has a ΔE of about 1 compared to the same polystyrene foam that does not contain a flame retardant compound.

The flame retardant compound is typically present in the composition in an amount of about 0.1 to about 10 weight percent of the composition. In one aspect, the flame retardant compound is present in an amount from about 0.3 to about 8 weight percent of the composition. In another aspect, the flame retardant compound is present in an amount of about 0.5 to about 7 weight percent of the polymeric material. In another aspect, the flame retardant compound is present in an amount of about 1 to about 5 weight percent of the composition. In another aspect, the flame retardant compound is present in an amount of about 3 to about 4 weight percent of the composition. While various example ranges are given here, it will be understood that the exact amount of flame retardant compound used will depend upon the degree of flame retardancy desired, the specific polymer used, and the end use of the resulting product.

The extruded foam of the present invention is formed from styrene polymers. Styrene polymers that can be used according to the invention include homopolymers and copolymers of vinyl aromatic monomers, ie monomers having unsaturated and aromatic moieties.

According to one aspect of the invention, the vinyl aromatic monomer has the formula:

[In the meal,

R is hydrogen or an alkyl group having 1 to 4 carbon atoms, and Ar is an aromatic group having about 6 to about 10 carbon atoms (including various alkyl and halo-ring-substituted aromatic units). Examples of such vinyl aromatic monomers include, but are not limited to, styrene, alpha-methylstyrene, ortho-methylstyrene, meta-methylstyrene, para-methylstyrene, para-ethylstyrene, isopropenyltoluene, isopropenyl Naphthalene, vinyl toluene, vinyl naphthalene, vinyl biphenyl, vinyl anthracene, dimethylstyrene, t-butylstyrene, some chlorostyrenes (eg mono- and dichloro-modifiers), and some bromostyrenes (eg mono-, di Bromo- and tribromo-variants).

According to one aspect of the invention, the monomer is styrene. Polystyrene is readily prepared by bulk or bulk, solution, suspension or emulsion polymerization techniques known in the art. The polymerization can be carried out with free radical, cationic or anionic initiators such as di-t-butyl peroxide, azo-bis (isobutyronitrile), di-benzoyl peroxide, t-butyl perbenzoate, dicumyl peroxide, potassium Persulfate, aluminum trichloride, boron trifluoride, etherate complex, titanium tetrachloride, n-butyllithium, t-butyllithium, cumyl potassium, 1,3-tririthiocyclohexane, etc. . Further details regarding the polymerization of styrene either alone or in the presence of one or more monomers copolymerizable with styrene are well known and are not described here in detail.

Polystyrene typically has a molecular weight of at least about 1,000. According to one aspect of the invention, the polystyrene has a molecular weight of at least about 50,000. According to another aspect of the invention, the polystyrene has a molecular weight of about 150,000 to about 500,000. However, it will be understood that if appropriate or desired, polystyrenes having a higher molecular weight can be used.

The flame retardant composition of the present invention may optionally comprise a synergist. The synergist may generally be present in an amount from about 0.01 to about 5 weight percent of the composition. In one aspect, the synergist is present in an amount from about 0.05 to about 3 weight percent of the composition. In another aspect, the synergist is present in an amount from about 0.1 to about 1 weight percent of the composition. In another aspect, the synergist is present in an amount from about 0.1 to about 0.5 weight percent of the composition. In another aspect, the synergist is present in an amount of about 0.4% by weight of the composition.

The ratio of the total amount of synergist to the total amount of flame retardant compounds can be from about 1: 1 to about 1: 7. According to one aspect of the invention, the ratio of the total amount of synergist to the total amount of flame retardant compounds is from about 1: 2 to about 1: 4. Examples of synergists that may be suitable for use in accordance with the present invention include, but are not limited to, dicumyl peroxide, iron (II) oxide, zinc oxide, zinc borate, and oxides of group V elements, for example, Oxides of bismuth, arsenic, phosphorus and antimony. According to one aspect of the invention, the synergist is dicumyl.

However, while the use of synergists has been described herein, it will be appreciated that no synergists are required to obtain effective flame retardant compositions. Thus, according to one aspect of the invention, the flame retardant composition is substantially free of synergists. According to another aspect of the invention, the flame retardant composition is substantially free of antimony compounds. According to another aspect of the invention, the composition comprises a synergist but is substantially free of antimony trioxide.

Flame retardant foams of the invention optionally comprise a heat stabilizer. Examples of heat stabilizers include, but are not limited to, zeolites; Hydrotalcite; Talc; Organotin stabilizers such as butyl tin, octyl tin, and methyl tin mercaptide, butyl tin carboxylate, octyl tin maleate, dibutyl tin maleate; Epoxy derivatives; Polymeric acrylic binders; Metal oxides such as ZnO, CaO and MgO; Mixed metal stabilizers such as zinc, calcium / zinc, magnesium / zinc, barium / zinc and barium / calcium / zinc stabilizers; Metal carboxylates such as zinc, calcium, barium stearate or other long chain carboxylates; Metal phosphates such as sodium, calcium, magnesium, or zinc; Or any combination thereof.

The heat stabilizer may generally be present in an amount from about 0.01 to about 10 weight percent of the flame retardant compound. In one aspect, the heat stabilizer is present in an amount from about 0.3 to about 10 weight percent of the flame retardant compound. In another aspect, the heat stabilizer is present in an amount from about 0.5 to about 5 weight percent of the flame retardant compound. In another aspect, the heat stabilizer is present in an amount from about 1 to about 5 weight percent of the flame retardant compound. In another aspect, the heat stabilizer is present in an amount of about 2% by weight of the flame retardant compound.

Other additives that may be used in the compositions and foams of the present invention include, for example, extrusion aids (eg, barium stearate or calcium stearate), or dicumyl compounds and derivatives, dyes, pigments, fillers, heat stabilizers , Antioxidants, antistatic agents, reinforcing agents, metal scavengers or deactivators, impact modifiers, processing aids, mold release agents, lubricants, antiblocking agents, other flame retardants, other thermal stabilizers , Antioxidants, UV stabilizers, plasticizers, flow aids, and similar materials. If desired, nucleating agents (eg, talc, calcium silicate, or indigo) can be included in the polystyrene composition to control cell size.

The flame retardant compositions of the invention can be used to form flame retardant polystyrene foams, for example extruded polystyrene foams. Flame retardant polystyrene foam can be prepared by any suitable process known in the art. Such foams can be used for a number of purposes, including but not limited to thermal insulation.

One example procedure involves melting the polystyrene resin in the extruder. The molten resin is then transferred to a mixer, for example a rotary mixer surrounded by a studded rotor in a housing having a studded inner surface with the rotor phase studs engaged. Molten resin and volatile foaming agent or blowing agent are fed to the inlet end of the mixer and discharged from the outlet end, generally flowing axially. From the mixer, the gel is passed through a cooler, which is passed through a die, which generally extrudes a rectangular plate. This procedure is described, for example, in US Pat. No. 5,011,866, which is incorporated by reference in its entirety. Other procedures, such as those described in US Pat. Nos. 3,704,083 and 5,011,866, each of which is incorporated by reference in its entirety, include the use of systems in which foams are extruded and foamed under subatmospheric, atmospheric and superatmospheric conditions. . Other examples of suitable foaming processes are described, for example, in US Pat. Nos. 2,450,436, each of which is incorporated by reference in its entirety; 2,669,751; 2,740,157; 2,740,157; 2,769,804; 2,769,804; 3,072,584; 3,072,584; And 3,215,647.

Various foaming or blowing agents can be used to make the flame retardant extruded polystyrene foam of the present invention. Examples of suitable materials are provided in US Pat. No. 3,960,792, which is incorporated herein by reference in its entirety. Aliphatic hydrocarbons including, for example, ethane, ethylene, propane, propylene, butane, butylene, isobutane, pentane, neopentane, isopentane, hexane, heptane, and any mixtures thereof; Volatile halocarbons and / or halohydrocarbons such as methyl chloride, chlorofluoromethane, bromochlorodifluoromethane, 1,1,1-trifluoroethane, 1,1,1,2-tetrafluoro Roethane, dichlorofluoromethane, dichlorodifluoromethane, chlorotrifluoromethane, trichlorofluoromethane, sym-tetrachlorodifluoroethane, 1,2,2-trichloro-1,1 , 2-trifluoroethane, sym-dichlorotetrafluoroethane; Volatile tetraalkylsilanes such as tetramethylsilane, ethyltrimethylsilane, isopropyltrimethylsilane, and n-propyltrimethylsilane, and any mixtures thereof, are widely used for this purpose. . One example of a fluorine-containing blowing agent is 1,1-difluoroethane provided under the trade name HFC-152a (FORMACEL Z-2, E.I. duPont de Nemours and Co.). Water-containing vegetable materials, such as finely divided corncobs, may also be used as blowing agents. Such vegetable materials can also be used as fillers, as described in US Pat. No. 4,559,367, which is hereby incorporated by reference in its entirety. Carbon dioxide can also be used as blowing agent or as a component thereof. Methods of using carbon dioxide as a blowing agent include, for example, US Pat. No. 5,006,566, each of which is incorporated herein by reference in its entirety; 5,189,071; 5,189,071; 5,189,072; 5,189,072; And 5,380,767. Other examples of blowing agents and blowing agent mixtures include water with or without nitrogen, argon, or carbon dioxide. If desired, such blowing agents or mixtures of blowing agents can be mixed with ethers, hydrocarbons or alcohols with suitable volatility. See, for example, US Pat. No. 6,420,442, which is incorporated herein by reference in its entirety.

Extruded polystyrene foam can typically include various components and additives in the relative amounts described above with respect to the composition used to form the foam. Thus, for example, the extruded polystyrene foam of the present invention may contain a flame retardant compound in an amount of about 0.1 to about 10 weight percent of the foam. In one aspect, the flame retardant compound is present in an amount from about 0.3 to about 8 weight percent of the foam. In another aspect, the flame retardant compound is present in an amount of about 0.5 to about 7 weight percent of the foam. In another aspect, the flame retardant compound is present in an amount from about 1 to about 5 weight percent of the foam. In another aspect, the flame retardant compound is present in an amount of about 3 to about 4 weight percent of the foam. While specific ranges and amounts are described herein, it will be understood that other relative amounts of constituents in the foam are contemplated by the present invention.

The invention is further illustrated by the following examples, which should not be construed as limiting the scope of the invention in any way. Rather, it will be apparent that after reading the disclosure herein various other aspects, embodiments, modifications, and equivalents thereof may be used that may be suggested to one skilled in the art without departing from the spirit of the invention and the scope of the appended claims.

Example 1

N, 2-3-dibromopropyl-4,5-dibromohexahydrophthalimide ("Compound (I)") was prepared according to the following typical procedure. Other procedures are known in the art and are not discussed herein.

A four-necked 5 L jacketed flask equipped with a nitrogen flow and water-cooled reflux condenser was charged with 900 g of xylene and 1 kg (6.57 mol) of tetrahydrophthalic anhydride (THPA, 95-96%). . To the stirred (250 rpm) slurry, allylamine (413 g, 7.23 mol) was added via an addition funnel for 45 minutes. The reaction was exothermic, and the temperature was maintained at 50 to 80 ° C. using a circulating bath fluid set at 30 ° C. After the allylamine addition was completed, the bath temperature was raised to 165 ° C. and maintained for 2 hours (complete reaction by GC). The circulating bath fluid temperature was lowered to 150 ° C. and the solvent was removed using a vacuum inhaler (˜3 ”Hg; Rxn T = 138 to 140 ° C.). After most of the xylene was removed, the bath temperature was 65 ° C. (Rxn T = 56 Reduced to 500 ° C. and 500 g of BCM (bromochloromethane) were added prior to washing with base detergent Aqueous solution (1,260 g water, 50 g Na ₂ CO ₃ ) was added, stirred and then phase separated. Dark red / brown organic phase (1,907 g: ˜500 g BCM, ˜1256 g product (65.8 wt.%), ˜200 g xylene) was separated from the orange aqueous phase (1,332 g) GC analysis was caustic. After completion of reaction, ~ 100 area% product was shown.

N-allyl- Tetrahydrophthalimide :

A four neck 5 L jacketed flask equipped with a nitrogen flow was charged with about 500 g of BCM, about 20 g of aqueous HBr and about 20 g of ethanol, and the circulation bath temperature was about 2 to 3 ° C. (reaction T = 5 ° C. first). ). In a stirred (300 rpm) solvent, about 2,209 g (13.8 mol, 2.1 to 2.2 eq) of bromine solution and THPAI (1,907 g) of BCM / xylene solution were added from the opposite side of the flask through an addition funnel for about 2.5 hours. On the surface, it was fed jointly. Reaction temperature was made into less than 33 degreeC. The solution is stirred for an additional 30 minutes and an aqueous solution of Na ₂ SO ₃ (20 g, 0.16 mol, FW = 126), Na ₂ CO ₃ (90 g, 0.85 mol, FW = 106), water (1450 g) is added. The organic phase was washed (aqueous phase pH = 8-9). Methanol (1.7 kg) was added to the reactor at 45 ° C. and the reaction temperature was raised to about 50 ° C. (bath T was about 68 ° C.). Another 1 kg of methanol was added while cooling the reactor to room temperature. The powder was filtered, rinsed with methanol and then dried at about 65 ° C. in an air circulation oven for about 2.5 hours to yield 2625 g of white powder product (76% yield). Mp 104-118 ° C.

Brominated N-allyl-tetrahydrophthalimide (62.6 wt.% Br):

Example 2

To illustrate flame retardant efficacy, various compositions containing N, 2-3-dibromopropyl-4,5-dibromohexahydrophthalimide ("Compound (I)") are prepared, which are typically Applied to ASTM Standard Test Method D 2863-87, referred to as Limit Oxygen Index (LOI) test. In this test, the higher the LOI value, the greater the flame retardancy of the composition.

After forming the concentrate (10 wt% compound I), the concentrate was placed in the pure resin at a ratio of about 35 wt% concentrate to about 65 wt% PS-168 neat resin and injected with carbon dioxide Sample A was prepared by extrusion molding a low density foam. PS-168 is a versatile non-flame retardant grade of non-reinforced crystalline polystyrene sold by Dow Chemical Company. The weight average molecular weight is about 172,000 Daltons, and the number average molecular weight is about 110,000 Daltons (measured by GPC). Molecular weight analysis was determined in THF with a Modular Waters HPLC system equipped with a Waters 410 differential refractometer and a Precision Detector model PD-2000 light scattering intensity detector. The column used to perform the separation was a 2 PL Gel Mixed Bed B column (Polymer Labs). Polymer Labs' polystyrene standards were used as calibration standards in the determination of molecular weight values.

The concentrate comprises about 10% by weight of compound (I), about 0.5% by weight of hydrotalcite heat stabilizer, about 4.3% by weight of Mistron Vapor Talc, about 1.5% by weight of calcium stearate, and about 83.7% by weight of Dow It contained PS-168. The concentrate was prepared on a Werner & Phleiderer ZSK-30 co-rotating twin screw extruder at a melt temperature of about 175 ° C. A standard dispersive mixing screw profile was used at a feed rate of about 250 rpm and about 8 kg / hour. The PS-168 resin was supplied via a single screw gravimetric feeder, premixed powder additives and supplied using a biaxial screw powder feeder.

The foam was then prepared by mixing the concentrate into pure Dow polystyrene PS-168 at a ratio of about 35% by weight to about 65% by weight of polystyrene, using the same twin screw extruder, under the following conditions: 1 Zone temperature (about 175 ° C), zone 2 temperature (about 160 ° C), zone 3 temperature (about 1300 ° C) and zone 4 temperature (about 1300 ° C), about 145 ° C die temperature, about 60 rpm screw speed, about 3.2 kg Per hour feed rate, 40/80/150 screen pack, about 290 to about 310 psig carbon dioxide pressure, about 160 ° C. melt temperature, about 63 to about 70% torque, and about 2 to about 3 ft / min leap ( takeoff) speed.

The foam contained about 1.5 wt% talc and about 3.5 wt% flame retardant (about 2.2 wt% bromine) as the nucleating agent for the foaming process. DHT4A hydrotalcite was also used to stabilize the flame retardant during the extrusion and foam-forming process in an amount of about 5 weight in the flame retardant compound. The foam was produced using a standard two-hole stranding die (holes 1/8 inch in diameter) with one hole closed. The resulting 5/8 inch diameter foam rod had a very thin skin (less than 0.005 inch) and a fine closed cell structure. Carbon dioxide gas was injected into barrel # 8 (ZSK-30 is a 9-barrel extruder). The rod was foamed with carbon dioxide at a density of about 9.0 lbs / ft ³ (0.14 specific gravity).

Control sample K was prepared as sample A, except the concentrate contained about 9% SAYTEX® HP900SG stabilized hexabromocyclododecane (HBCD).

The evaluation results are shown in Table 1 below.

The results indicate that N, 2-3-dibromopropyl-4,5-dibromohexahydrophthalimide is a high potency flame retardant comparable to HBCD on the market.

Example 3

The thermal stability of N, 2-3-dibromopropyl-4,5-dibromohexahydrophthalimide ("Compound (I)") used according to the invention was evaluated using a thermal HBR measurement test.

First, about 0.5 to about 1.0 g of a flame retardant sample was weighed and placed in a three neck 50 mL round bottom flask. Teflon tubing was then attached to one of the openings in the flask. Nitrogen was fed into the flask through a Teflon tube at a flow rate of about 0.5 SCFH. A small reflux condenser was attached to another opening on the flask. The third opening was closed. A solution of about 50% by volume of glycol in water was flowed through the reflux condenser at a temperature of about 85 ° C. Viton tubing was attached to the top of the condenser and gas scrubbing vessels. Two other containers were attached to the first one in series. All three bottles had about 90 mL of about 0.1 N NaOH solution. After the instrument was assembled, nitrogen was purged through the system for about 2 minutes. The round bottom flask was then placed into the oil bath at about 22O <0> C and the sample was heated for about 15 minutes. The flask was then removed from the oil bath and purged with nitrogen for about 2 minutes. The contents of three gas cleaning vessels were transferred to a 600 mL beaker. The vessel and the viton tube were rinsed off with a beaker. The contents were then acidified with about 1: 1 HNO ₃ and titrated with about 0.01 N AgNO ₃ . The sample was run twice to record the average of both measurements. Lower thermal HBr values are preferred for heat stable flame retardants in extruded polystyrene foam or extruded polystyrene foam.

SAYTEX® HP-900 was also evaluated as described above. SAYTEX® HP-900 is a HBCD marketed by Albemarle Corporation.

The evaluation results are shown in Table 2 below.

The results of the evaluation indicate that the flame retardant described herein is thermally stable not to decompose to excessive release of heat cut HBr upon heating to the typical operating temperature used in the extruded polystyrene foam.

Example 4

Melt stability of N, 2-3-dibromopropyl-4,5-dibromohexahydrophthalimide ("Compound (I)") in polystyrene was also evaluated. Samples were prepared and subjected to ASTM standard test method D 3835-90, commonly referred to as melt stability test.

Various samples containing about 10% by weight of the compound (I) concentrate in polystyrene were heated in the barrel and extruded over time. Dynisco-Kayeness Polymer Test Systems LCR 6052 Flowmeter (Model D6052M-115, Serial No. 9708-454) / WinKARS instrument / software package was used to measure viscosity as a function of time in a heated barrel. For a dwell time of about 6.5, 13, 9.5, 25.9 and 32.4 minutes, the evaluation was carried out at a shear rate of 500 sec ^{- 1} using a 9.55 mm barrel diameter and 20/1 L / d tungsten carbide die. . For thermally stable materials, the viscosity should not change substantially over time.

Samples A and K were described above in Example 2. The control sample, PS-168, is PS-168 polystyrene resin (no flame retardant compound).

About 13% by weight of the following Compound (II), about 0.5% by weight of hydrotalcite heat stabilizer, about 4.3% by weight of Mistron Vapor Talc, about 1.5% by weight of calcium stearate and about 80.7% by weight of Dow PS-168 Comparative Sample L was prepared by preparing a PS-168 resin concentrate containing.

The concentrate was prepared on a Werner & Phleiderer ZSK-30 idle twin screw extruder at a melt temperature of about 175 ° C. A standard dispersion kneading screw profile was used at a feed rate of about 250 rpm and about 8 kg / hour. The PS-168 resin concentrate and powder additives were premixed and fed through a single screw gravimetric feeder. The concentrate flowed insufficiently and turned dark orange over time. Gas emissions occurred with loss of resin melt strength. Stretching was not possible about 10 minutes after extrusion.

About 12.5% by weight of the following Compound (III), about 0.5% by weight of hydrotalcite heat stabilizer, about 4.3% by weight of Mistron Vapor Talc, about 1.5% by weight of calcium stearate, and about 81.2% by weight of Dow PS- Comparative Sample M was prepared by preparing a PS-168 resin concentrate containing 168.

The concentrate was prepared on a Werner & Phleiderer ZSK-30 co-rotating twin screw extruder at a melt temperature of about 175 ° C. A standard dispersion kneading screw profile was used at a feed rate of about 250 rpm and about 8 kg / hour. The PS-168 resin concentrate and powder additives were premixed and fed through a single screw gravimetric feeder. The concentrate flowed moderately in that the melt strength was maintained and the drawing was good, but the material turned dark red orange from the beginning. Initial gas evolution was stable after about 5 to 10 minutes.

The evaluation results are shown in Tables 3 and 4 below.

The shear viscosity of the sample A-concentrate at 175 ° C. was stable at 175 ° C. (within its initial value of 5%). Sample A-concentrate began to show some less instability at 20O &lt; 0 &gt; C, indicating a decrease of about 13% in shear viscosity.

In the shear viscosity of the sample L-concentrate, it began to show instability at 175 ° C at the end of the evaluation, as the initial value thereof fell over 15%. The shear viscosity of the sample M-concentrate was stable in its flow characteristics for a residence time of 32-minutes throughout the test, and its shear viscosity was stable (within 5% of the initial value) throughout the measurement. The shear viscosity of the sample L-concentrate and the M-concentrate at 19 ° C. was not measured.

Example 5

The impact of extrusion on the molecular weight of the various flame retardant concentrates and foams was determined by evaluating the samples using GPC before and after extrusion.

Samples A and K are described in Example 2. Samples L, M, N and PS-168 were described in Example 4. Sample N was prepared as in Example 2, except that 30 wt.% Of the following compound (IV) was used in place of compound (I).

The concentrate contained about 30% by weight (1.11 kg) of compound (IV) and about 70% by weight (2.59 kg) of PS-168. The concentrate was prepared on a Leistritz / Haake Micro 18 counter-rotating twin screw extruder at a melt temperature of about 17O <0> C. A standard dispersion kneading screw profile was used at a feed rate of about 100 rpm and about 3 kg / hour. The polystyrene resin concentrate and powder additives were premixed and fed using a single-screw gravimetric feeder. Extruded strands exhibited weak foaming and odor, suggesting heat release of HBr.

The results indicate that compound (I) is highly stable, causing degradation of polystyrene, if any, to a minimum. In contrast, compounds (II) and (IV) significantly degrade polystyrene and are therefore not suitable for producing flame retardant extruded polystyrene foams.

Example 6

The Hunter Lab ColorQUEST spectroscopic colorimeter (diffusion geometry) is delta E (ΔE) for various flame retardant concentrates according to ASTM D6290-98 "Standard Test Method for Color Determination of Plastic Pellets". ) Was used to measure.

Samples A, K, L, M, N and PS-168 were described above. The results are shown in Table 6 below.

The results show that compound (I) is very suitable for use in forming polystyrene foams. The lack of color change demonstrates high thermal stability with little or no polymer degradation. Sample L-foams and M-foams have significant coloration that makes flame retardant compounds (II) and (III) inadequate for the formation of extruded polystyrene foam.

The foregoing description has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise examples or embodiments disclosed. Obvious modifications or variations are possible in light of the above teachings. Choosing and describing an embodiment or an embodiment discussed, provides the best explanation of the principles of the present invention and its practical uses, various modifications of which are possible in various respects and to the particular applications contemplated, thereby allowing the present invention to be modified by those skilled in the art. Made available. All such modifications and variations are within the spirit of the invention, as determined by the appended claims, when interpreted according to the scope in which they are clearly and legally entitled.

In the following claims, the present tense (“comprises”, “comprises”, etc.) may refer to materials, components and / or components, all in accordance with the teachings of the present invention, one or more other materials, components Reference to a component and / or a substance, component or component as it is if it is not formed in solution, as it is present immediately before contacting, blending or mixing with, or as formed in solution. If performed in accordance with the present disclosure, it is not a problem that a substance, component or component may lose its original identity through chemical reactions or modifications during the process of contacting, blending, mixing, or in situ formation. Do not.

Claims (1)

A flame retardant extruded polystyrene foam containing N, 2,3-dibromopropyl-4,5-dibromohexahydrophthalimide (CAS. No. 93202-89-2) as a flame retardant, wherein the flame retardant extruded polystyrene The foam is a flame retardant extruded polystyrene foam having a ΔE of 0 to 10 when compared to the extruded foam made from polystyrene without flame retardant.