MXPA01002166A - Fire resistant styrene polymer foams with reduced brominated fire retardant - Google Patents

Abstract

Extruded, substantially closed-polystyrene foams that exhibit improved fire resistance yet contain lower levels of brominated fire retardant are disclosed. Methods of preparing the foams, comprising extruding the polystyrene with a novel fire retardant formulation comprising a mixture of a) a phosphate compound, preferably TPP;b) less than about 2.5 percent HBCD based on 100 percent polystyrene;and optionally c) a flow promoter such as dimethyldiphenylbutane, the extrusion process using a blowing agent which is preferably selected from carbon dioxide, mixtures of two or more of carbon dioxide, water, alcohol, ether and hydrocarbons, or a mixture of hydrofluorocarbons, alcohols, and hydrocarbons, are also disclosed. Use of the phosphate compound in the fire retardant formulation allows a reduction in the amount of brominated compound required and a reduction in the foaming temperature, resulting in lower density foams.

Description

FIRE-RESISTANT STYRENE POLYMER FOAMS WITH REDUCED, REDUCED IGNITION RETARDER Field of the Invention The present invention relates to fire-resistant styrene polymer foams or ignition retardants and, in particular, refers to flame retardant or fire retardant styrene polymer foams having a brominated, reduced ignition retardant. .

BACKGROUND OF THE INVENTION During the last decades, polymer foams have become available in a wide variety of ways, either in response to a material industry need or as an expansion of commercialized precursors development. Some of the most popular forms of foamed polymer compositions take the form of films, sheets, plates and profiles. Generally, these products are produced by extrusion methods in which the polymer is converted by heat and pressure into a homogeneous mixture and forced through a nozzle to the desired configuration. To obtain a cellular structure, the plastic normally incorporates a blowing agent that decomposes in the heat of the extrusion process and releases gases that cause the form to expand. It is also possible to inject propellants directly into the fusion. Due to the favorable combination of properties, price and Ease of processing, styrene polymers, especially polystyrene, are widely used in the preparation of foam sheets, films and plates for such divergent terminal uses as packaging, pipe, construction and insulation. For example, expanded styrene polymers, such as polystyrene, are widely used in the insulation of freezers, refrigerators, towing bodies, wagons, crop constructions, roof decks and residential accommodations. Styrene polymer foams are also used as the core material of structural sandwich panels used in refrigerated trailer bodies, mobile homes and recreational vehicles. There is a growing demand to improve the ignition retardant properties of materials used in vehicles, construction materials and consumer goods such as furniture, radio and television booths, household appliances, electric motor housings and electrical sockets. To meet this demand, various steps have been taken to improve the flame-retardant properties of the thermoplastic polymers in order to slow them down to ignition and retard the propagation of the flame. The thermoplastic polymers can become flame retardants by being conformed with flame retardant additives, including halogenated organic compounds and inorganic compounds such as antimony oxide. Brominated organic compounds have been used in both foamed and non-foamed styrene polymer compositions, the polymer foam products being made from styrene more resistant to ignition with a brominated ignition retardant, which optionally includes a radical generator synergist or a flow promoter. Of the various brominated organic compounds, typically only brominated aliphatics are used with vinylaromatic foams, the most common being hexabromocyclododecane (HBCD). Although efficient in the rate of ignition retardation, the incorporation of ignition retardant additives in the thermoplastic polymer compositions can adversely impact the strength of the foam, particularly at higher levels of such additives. In non-foamed polymers, the bromine content is typically quite high, for example, of more than 5 parts of bromine per 100 parts of styrene polymer. However, in foamed styrene polymers, the degree of bromine loading has to be significantly lower to avoid the deleterious impact of the structural qualities and the dermal quality of the foam. For exampleWhen HBCD is used as an ignition retardant in a styrene polymer foam, a high level of HBCD is required in order to meet the flame retardant requirements, particularly the strict European ignition delay tests. Depending on the characteristics of the foam (e.g., density, blowing agents, etc.), the amount of HBCD typically required to meet the flame retardant requirements is from 2.5 percent to 4 percent by weight of the styrene polymer ( the higher the density of the foam, the higher the percentage of HBCD). However, the incorporation of HBCD into the polymer foam of Styrene at these levels can result in 1) a poor dispersion of HBCD in the foam, resulting in non-uniform expansion and poor dermal quality and 2) a high degree of degradation of the styrene polymer and the material swirled in the process of extrusion due to excessive heat, resulting in a reduction in the molecular weight of the styrene polymer foam and the re-styled polymer and a resultant drop in physical properties. Accordingly, there remains a need in the art for ignition retardant styrene polymer foams, which utilize hexabromocyclododecane (HBCD) as the ignition retardant, which meets the flame retardant requirements and which is subject to extrusion processes, but which does not exhibit structural qualities and / or poor dermal qualities. Those needs are met by the present invention. In this manner, the present invention provides foamed styrene, ignition retardant, extruded polymer compositions utilizing hexabromocyclododecane (HBCD) as the ignition retardant, which complies with the flame retardant requirements and which is subject to processes of ignition. extrusion but which does not exhibit structural qualities and / or poor dermal qualities. The extruded, invented, flame retardant, styrene polymer compositions of the present invention utilize an ignition retardant formulation which is comprised of a mixture of hexabromocyclododecane (HBCD) and a phosphorous compound. The use of the phosphorous compound in the ignition retardant formulation allows the use of less than about 2.5 percent of HBCD while maintaining a high level of fire resistance. Because a lower level of HBCD is used, the foams of the present invention do not suffer from poor structural qualities and / or dermal qualities. In addition, the use of such an ignition retarding composition allows a production of polystyrene foam with a lower foam density, thus making appreciable cost savings.

BRIEF DESCRIPTION OF THE PREFERRED MODALITY Thus, in one embodiment of the present invention, there is provided a polymer foam composition comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, of HBCD; and 2) from 0.1 percent to 4.0 percent by weight, based on 100 percent styrene polymer, of a phosphorous compound. In another embodiment, a polymer foam composition is provided comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 1 00 percent styrene polymer, of HBCD; and 2) from 0.1 percent to 4.0 percent by weight, based on 100 percent styrene polymer, of a phosphorous compound; and c) 0.01 percent up to 0.2 weight percent based on 100 percent styrene polymer from a flow promoter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention provides an extruded, retardant, styrene polymer foam, in which the ignition retardant formulation is comprised of a mixture of HBCD and a phosphorous compound. The use of the phosphorous compound in the ignition retardant formulation allows the use of less than about 2.5 percent HBCD while maintaining a high level of fire resistance. Because a lower level of HBCD is used, the HBCD disperses well in the foam and the foam expands uniformly with good dermal quality. In addition, the presence of the phosphorous compound results in a lower density foam. A foam with lower density is formed even when the foaming temperature is lowered to quantify the decrease in glass transition temperature of the styrene polymer (due to the higher solubility of the phosphate compound in the styrene polymer). The foamed polymer, ignition retardant compositions of the present invention comprise: a) a styrene polymer; b) an ignition retardant formulation comprising HBCD and a phosphorous compound; and optionally, c) a flow promoter. Styrene polymers suitable for use in the present invention include polystyrene or a copolymer formed from styrene monomer and unsaturated, ethylenically copolymerizable comonomers. The comonomer content is typically less than about 50 percent and preferably less than about 20 percent based on the weight of the styrene polymer.

Examples of copolymerized compounds include α-methylstyrene, acrylonitrile, acrylic or methacrylic acids having from one to eight carbon atoms, esters of acrylic or methacrylic acid with alcohols having from one to eight carbon atoms, fumaric ethers having one to eight carbon atoms. to eight carbon atoms, maleic anhydride or a small amount of divinyl benzene. The HBCD portion of the ignition retardant formulation is present in the styrene polymer foam in an amount of less than about 2.5 weight percent based on 100 percent of the styrene polymer, with amounts less than 2.0 percent being preferred, more amounts from 1.0 percent to 1.6 percent, and especially an amount of 1.4 percent. The phosphorous compound portion of the ignition retardant formulation can be any organic compound that contains one or more phosphorus atoms and includes, but is not limited to, phosphates of the formula (RO) 3PO wherein each R is independently selected from an aliphatic branched or straight chain element, saturated or unsaturated, substituted or unsubstituted or of a substituted or unsubstituted aromatic element. Suitable phosphates include, but are not limited to, triphenyl phosphate (TPP), tributylphosphate, triethylphosphate, trimethylphosphate, tripropylphosphate, trioctyl phosphate, diphenyl cresylphosphate, diphenyl methyl phosphate, tris- (2-ethylhexyl) phosphate, isodecyl diphenyl phosphate, isooctyl diphenyl phosphate, diphenyl phosphate. of bisphenyl, trichilyl phosphate and triisopropylphenyl phosphate. Other phosphorous compounds suitable for use in the present invention are the phosphites of the formula (RO) 3P, phosphonates of the formula (RO) 2RPO, phosphinates of the formula (RO) R 2 PO, phosphine oxides of the formula R 3 PO, phosphines of the formula R 3 P, and phosphonium salts of the formula R 4 PX, wherein each R is independently selected from aliphatic branched or straight chain elements, saturated or unsaturated, substituted or unsubstituted or substituted or unsubstituted aromatic elements and X is a suitable counter ion, such as chloride or bromide. Of the phosphorous compounds described above, phosphates are preferred and TPP is especially preferred. The phosphorous compound is present in the styrene polymer foam in an amount from 0.1 percent to 4.0 percent by weight based on 100 percent of the styrene polymer, with 0.5 percent being preferred up to 2.0 percent, with 1.0 percent being preferred. percent up to 2.0 percent. The polystyrene ignition retardant formulations of the present invention may optionally include a flow promoter (molten flux modifiers) to aid in the initiation of the decomposition of HBCD. By providing a source of reactive radicals (generated at a temperature below HBCD) that separates protons from the aliphatic portion (s) of HBCD and subsequently releases the bromine radical, the flow promoters are able to help to the degradation of HBCD. In addition, the reactive radicals of the flow promoter are capable of breaking the styrene polymer chain during a fire, thus allowing the foam to be kept separate from the source of the fire. Suitable flow promoters include 2,3- dimethyl-2,3-diphenylbutane (ie, dicumyl or DMDPB); dicumyl peroxide; a, a'-bis-tert-butylperoxydiisopropylbenzene; bis (α-phenylethyl) sulfone; 1,1 '-diphenylbicyclohexyl; 2,2'-dimethyl-2,2'-azobutane; 2,2'-dichloro-2,2'-azobutane; 2,2'-dibromo-2,2'-azobutane; 2,2'-dimethyl-2,2'-azobutane-3,3 ', 4,4'-tetracarboxylic acid; 1,1 '-diphenylbicyclopentyl; 2,5-bis (tribromomethyl) -1,3,4-thiadiazole; 2- (bromophenyl-5-tribromophenyl) -2,3,4-thiadiazole; dioctyl tin maleate; and dibutyl tin maleate. The most preferred flow promoter for use in the present invention is dimethyldiphenylbutane (ie, dicumyl or DMDPB). Typically, when used, the flow promoter is presented in the styrene polymer foam in an amount from 0.01 percent to 0.2 percent by weight based on 100 percent styrene polymer, with 0.02 percent to 0.1 percent preferred. percent and especially prefer 0.03 percent to 0.08 percent. Various additives may also be incorporated into the present foam such as inorganic fillers, pigments, dyes, antioxidants, acid expellers, ultraviolet absorbers, ignition retardants, processing aids, dispersing agents and extrusion aids. Based on the foregoing, the following are typical foaming polymer, flash retardant compositions of the present invention: A polymer foam comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably from 1.0 to 1.6 percent, and more preferably 1.4 percent, of HBCD; and 2) from 0.1 percent to 4.0 percent by weight, based on 1 00 percent styrene polymer, of a phosphorous compound; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably 1.0 to 1.6. one hundred and more preferably 1.4%, of HBCD; and 2) from 0.5 percent to 2.0 percent by weight, based on 100 percent styrene polymer, of a phosphorous compound; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably 1.0 to 1.6. one hundred and more preferably 1.4%, of HBCD; and 2) from 1.0 percent to 2.0 percent by weight, based on 100 percent styrene polymer, of a phosphorous compound; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably from 1.0 to 1.6%, and more preferably 1.4%, of HBCD; and 2) about 1.0 percent by weight, based on 100 percent styrene polymer, of a phosphorous compound; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably 1.0 to 1.6. one hundred and more preferably 1.4%, of HBCD; and 2) from 0.1 percent to 4.0 percent by weight, based on 100 percent styrene polymer, of a phosphorous compound; and c) 0.01 percent up to 0.2 weight percent, based on 100 percent styrene polymer, of a flow promoter; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably 1.0 to 1.6. one hundred and more preferably 1.4%, of HBCD; and 2) from 0.5 percent to 2.0 percent by weight, based on 1 00 percent styrene polymer, of a phosphorous compound; and c) 0.01 percent up to 0.2 weight percent, based on 100 percent styrene polymer, of a flow promoter; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably from 1.0 to 1.6%, and more preferably 1.4%, of HBCD; and 2) from 1.0 percent to 2.0 percent by weight, based on 1 00 percent styrene polymer, of a phosphorous compound; and c) 0.01 percent up to 0.2 weight percent, based on 100 percent styrene polymer, of a flow promoter; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably 1.0 to 1.6. one hundred and more preferably 1.4% of HBCD; and 2) 1.0 percent by weight, based on 100 percent styrene polymer, of a phosphorous compound; and c) 0.01 percent up to 0.2 weight percent, based on 100 percent styrene polymer, of a flow promoter; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably 1.0 to 1.6. one hundred and more preferably 1.4%, of HBCD; and 2) from 0.1 percent to 4.0 percent by weight, based on 100 percent styrene polymer, of TPP; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably from 1.0 to 1.6%, and more preferably 1.4%, of HBCD; and 2) from 0.5 percent to 2.0 percent by weight, based on 100 percent styrene polymer, of TPP; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably 1.0 to 1.6. one hundred and more preferably 1.4%, of HBCD; and 2) from 1.0 percent to 2.0 percent by weight, based on 100 percent styrene polymer, of TPP; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably 1.0 to 1.6. one hundred and more preferably 1.4%, of HBCD; and 2) about 1.0 percent by weight, based on 100 percent styrene polymer, of TPP; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably 1.0 to 1.6. one hundred and more preferably 1.4%, of HBCD; and 2) from 0.1 percent to 4.0 percent by weight, based on 100 percent styrene polymer, of TPP; and c) 0.01 percent to 0.2 percent by weight, based on 100 percent of styrene polymer, from a flow promoter; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably 1.0 to 1.6. one hundred and more preferably 1.4%, of HBCD; and 2) from 0.5 percent to 2.0 percent by weight, based on 100 percent styrene polymer, of TPP; and c) 0.01 percent up to 0.2 weight percent, based on 100 percent styrene polymer, of a flow promoter; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably 1.0 to 1.6 percent, and more preferably 1.4 percent, of HBCD; and 2) from 1.0 percent to 2.0 percent by weight, based on 100 percent styrene polymer, of TPP; and c) 0.01 percent up to 0.2 weight percent, based on 100 percent styrene polymer, of a flow promoter; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably 1.0 to 1.6. one hundred and more preferably 1.4%, of HBCD; and 2) about 1.0 percent by weight, in base at 1 00 percent styrene polymer, TPP; and c) 0.01 percent up to 0.2 weight percent, based on 1 00 percent styrene polymer, of a flow promoter; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably 1.0 to 1.6. one hundred and more preferably 1.4%, of HBCD; and 2) from 0.1 percent to 4.0 percent by weight, based on 100 percent styrene polymer, from TPP; and c) 0.01 percent to 0.2 weight percent, based on 1 00 percent styrene polymer of dimethyldiphenylbutane; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably 1.0 to 1.6. one hundred and more preferably 1.4%, of HBCD; and 2) from 0.5 percent to 2.0 percent by weight, based on 100 percent styrene polymer, of TPP; and c) 0.01 percent up to 0.2 weight percent, based on 100 percent styrene polymer of dimethyldiphenylbutane; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably from 1.0 to 1.6%, and more preferably 1.4%, of HBCD; and 2) from 1.0 percent to 2.0 percent by weight, based on 100 percent styrene polymer, of TPP; and c) 0.01 percent to 0.2 weight percent, based on 1 00 percent styrene polymer of dimethyldiphenylbutane; a polymer foam, comprising: a) a styrene polymer; and b) an ignition retardant formulation comprising: 1) less than about 2.5 weight percent, based on 100 percent styrene polymer, preferably less than 2.0 percent, more preferably 1.0 to 1.6. one hundred and more preferably 1.4%, of HBCD; and 2) about 1.0 percent by weight, based on 100 percent styrene polymer, of TPP; and c) 0.01 percent up to 0.2 weight percent, based on 100 percent styrene polymer of dimethyldiphenylbutane. The foams of the present invention can be prepared by extrusion processes well known to those of ordinary skill in the art. A typical apparatus for making the foam according to an extrusion process is comprised of an extruder, a mixer, a refrigerator and a nozzle in series. Typically, the apparatus is maintained in such a way that the feeding zone is maintained at 120 ° C to 160 ° C, the melting zone is maintained at 150 ° C to 190 ° C, the measuring zone is maintained at 180 ° C up to 220 ° C and the mixing zone is maintained at 180 ° C to 200 ° C. The HBCD ignition retardant is in the form of a powder or as a granulate.

Depending on the physical state of the phosphorous compound (ie, liquid or solid), the phosphorous compound can be injected directly into the mixer or introduced directly into the extruder. Alternatively, the phosphorous compound can be introduced in the form of a styrene polymer concentrate. The flow promoter, due to its low concentration required, is normally used in the form of a styrene polymer concentrate. All solid materials are fed into the extruder, while liquid materials can be injected directly into the mixer. The ignition retardant formulation and the other additives are mixed with the styrene polymer resin in the desired ratio. The blowing agent is then incorporated into the mixed polymer melt at an elevated pressure in the mixer to form a swellable gel. The temperature of the sponge gel is reduced to a suitable foaming temperature (typically about 120 ° C) by reducing the temperature of the cooling zone. The foamable gel is then transported through the nozzle to a region of reduced pressure to form the foam, adjusting the nozzle opening as required and expanding the foam between the substantially parallel forming plates. The structure of the foam is preferably closed cell and has a closed cell content of at least 90 percent according to ASTM D-2856. The structure of the foam preferably has a density of 16 kg / m3 to 80 kg / m3 according to ASTM D-1622. The foam also has an average cell size of 0.05 to 2.4 mm. Blowing agents suitable for use in the present invention can be CO 2 or mixtures of blowing agents in any of the following proportions: C 0 2: from 0 percent to 100 percent of the blowing agent mixture; Alcohol: from 0 percent to 50 percent of the blowing agent mixture; Water: from 0 percent to 50 percent of the blowing agent mixture; Dimethyl ether: from 0 percent to 50 percent of the blowing agent mixture; Hydrocarbon: from 0 percent to 50 percent of the blowing agent mixture; HFC-134a: from 0 percent to 80 percent of the blowing agent mixture; HFC-152a: from 0 percent to 80 percent of the blowing agent mixture; and HFC-134: from 0 percent to 80 percent of the blowing agent mixture, where HFC-1 34 is 1, 1, 2,2-tetrafluoroethane, HFC-1 34a is 1, 1, 1 -2 -tetraf luoroethane and HFC-152a is 1,1-difluoroethane. Preferred blowing agents are 100 percent C02, mixtures of CO2, water, alcohol, dimethyl ether and hydrocarbon and mixtures of HFC-134a, HFC-134 and / or HFC-152a, alcohol and hydrocarbon. The blowing agent is typically used at a concentration of between 0.05 to 0.20 moles / 100 g of polystyrene.

The following are examples of the present invention and should not be considered as limiting. Unless stated otherwise, all percentages, parts or proportions are by weight. Examples 1 to 3 and Comparative Examples A to E Closed cell styrene polymer foams in accordance with the present invention are prepared using a 5.08 cm diameter extruder feeding a slit mixer into which the release agents are injected. blown. The discharge of the slot mixer is passed through heat exchangers. The discharge from the heat exchangers is passed through a static mixer and expanded through a slot die towards a lower pressure region. The styrene polymer is fed into the extruder with an ignition retardant formulation comprising HBCD and optionally dimethyldiphenylbutane (dicumyl) of dicumyl concentrate of 17 percent pure dicumyl and the TPP is injected hot melt directly into the mixer, in accordance with the present invention, in amounts indicated in Table I. The blowing agents were injected into the mixer in amounts also indicated in Table I. The foamable gel was cooled to about 120 ° C and extruded through the nozzle and expands between the substantially parallel forming plates. Table 1 shows the composition and foam properties of the three foams of the present invention (Examples 1 to 3) as well as also five control foams (Comparative Examples A to E) for comparative purposes. The foams of Comparative Examples A to D were produced with only HBCD (HBCD) as the ignition retardant. The amount of HBCD was increased from 1 to more than 2.7 percent of HBCD, in order to achieve a bromine concentration ranging from 0.5 to 2 percent. All other additives remained unchanged. The foam of Comparative Example E was produced with an ignition retardant composed of 5.5 percent triphenyl phosphate and 0.068 percent dicumyl. The percentage of bromine in the foam is determined by the use of the Oxford Lab X1005 X-ray Fluorescence analyzer. The foam is subjected to X-ray radiation from a radioactive source of Cadmium and the X-rays correspond to the energy of the bromine element. By measuring the intensity of the emitted X-rays, it is possible to quantify the bromine element in the sample. The percentage of bromine is obtained from an average measurement of the three foam specimens. The compressive strength is determined with the method ASTM 1621-79.

Table I r The performance of the fire and the performance of the ignition delay are indicated in Table II, where the fire performance is measured according to the Limited Oxygen Index (LOI) and the ignition delay performance is measured according to the German B2 test, French M1 test and Swiss Class V test. The Limited Oxygen Index (LOI) is determined according to test method ASTM-D2863. This is the minimum oxygen concentration, expressed as a volume percent, in a mixture of oxygen and nitrogen that will only withstand the combustion of ignition of a material initially at room temperature under the conditions of this test method. The German test B2 is carried out according to DIN-4102 part 1. Five samples were examined. The lower the average height of the flame, the better the performance of the ignition delay. The burning time should also be as low as possible. If the filter paper below the sample catches fire within 20 seconds, the material is considered to be ignited by flame drops, the number reported in Table II is the number of papers lit during the test. The French M1 test was carried out according to NF-P 92-501/4/5 composed of two tests: persistence of the flame and dripping of the ignition. Three samples were examined. The average time for the flame to self-extinguish should be as low as possible. The percentage of the number of burners with an ignition time above 2 percent as well as the number of drips of lit should be as small as possible. The Swiss test was carried out according to SIA 183 / 2.5. The lower the average weight of the flame, the better the fire retardant performance.

Table As can be seen from Table I and Table II, the formulations according to the present invention showed a lower foam density than the foams of the Comparative Examples, although the formulations were produced at a lower foaming temperature. The foam products, according to the invention, showed good fire performance in the German B2 test, the Swiss and French M1 ignition delay tests. To achieve that performance, very high amounts of HBCD (ie, high percentage of bromine) are required for the comparative foam. The foams of the present invention also exhibited excellent dimensional stability and mechanical properties, such as comparative foams. However, the foams of the present invention exhibited good mechanical properties despite having a lower density. Accordingly, the foams of the present invention are suitable for use in building insulation and building applications.

Claims (20)

1. CLAIMS 1. A foamed polymer composition, ignition retardant, characterized in that it comprises: a) a styrene polymer which is polystyrene or a copolymer of styrene monomer and copolymerizable ethylenically unsaturated comonomer (s), selected from of the group consisting essentially of α-methylstyrene, acrylonitrile, acrylic or methacrylic acids having from one to eight carbon atoms, esters of acrylic or methacrylic acid with alcohols having from one to eight carbon atoms, fumed esters having one to eight carbon atoms, maieic anhydride and a small amount of divinylbenzene, and b) an ignition retardant formulation comprising: 1) hexabromocyclododecane in an amount less than about 2.5% by weight based on 100% styrene polymer and 2) a phosphorous compound in an amount of from about 0.1% to about 4.0% by weight based on 100% polymer of styrene wherein the phosphorous compound is selected from 1) phosphates of the formula (RO) 3PO; 2) phosphonates of the formula (RO) 2RPO; 3) phosphinates of the formula (RO) R 2 PO; 4) oxides of phosphine of the formula R3PO, 5) phosphines of the formula R3P; and 6) phosphonium salts of the formula R4PX, wherein each R is independently selected from aliphatic branched or straight chain elements, saturated or unsaturated, substituted or unsubstituted or substituted or unsubstituted aromatic elements and X is an adequate counter ion.
2. 2. The polymer composition according to claim 1, characterized in that it further includes from about 0.01% to about 0.2% by weight based on 100% styrene polymer of a flow promoter.
3. 3. The polymer composition according to claim 2, characterized in that the flow promoter is selected from dimethyldiphenylbutane, dicumyl peroxide or a, a'-bis-tert-butylperoxydiisopropylbenzene.
4. 4. The polymer composition according to claim 3, characterized in that the flow promoter is dimethyldiphenylbutane.
5. 5. The polymer composition according to any of claims 1 to 4, characterized in that the phosphorous compound is a phosphate of the formula (RO) 3PO wherein each R is independently selected from branched or straight chain aliphatic elements, saturated or unsaturated, substituted or unsubstituted or substituted or unsubstituted aromatic elements
6. 6. The polymer composition according to claim 5, characterized in that the phosphate is selected from triphenyl phosphate, tributylphosphate, triethyl phosphate, trimethyl phosphate, tripropyl phosphate, trioctyl phosphate, diphenyl methyl phosphate, tris- (2-ethylhexyl) phosphate, isodecyl diphenyl phosphate, isooctyl diphenyl phosphate, bisphenyl diphenyl phosphate, trixlyl phosphate and triisopropylphenyl phosphate.
7. 7. The polymer composition according to claim 6, characterized in that the phosphate is triphenyl phosphate.
8. 8. The polymer composition according to any of claims 1 to 7, characterized in that the hexabromocyclododecane is present in an amount of less than about 2.0% by weight based on 100% styrene polymer.
9. 9. The polymer composition according to any of claims 1 to 8, characterized in that the phosphorous compound is present in an amount of from about 0.5% to about 2.0% by weight based on 100% styrene polymer.
10. The polymer composition according to any of claims 1 to 9, characterized in that the flow promoter is present in an amount of from about 0.02% to about 0.1% by weight based on 100% styrene polymer. eleven .
11. The polymer composition according to claim 10, characterized in that the flow promoter is present in an amount of from about 0.03% to about 0.08% by weight based on 100% styrene polymer.
12. 12. The polymer composition according to claim 9 or 10, characterized in that the hexabromocyclododecane is present in a amount from about 1.0% to about 1.6% by weight based on 100% styrene polymer.
13. The polymer composition according to claim 12, characterized in that the hexabromocyclododecane is present in an amount of about 1.4% by weight based on 100% styrene polymer.
14. 14. The polymer composition of any of claims 1 to 13, characterized in that the phosphorous compound is present in an amount of from about 1.0% to about 2.0% by weight based on 100% styrene polymer.
15. 15. The polymer composition according to claim 14, characterized in that the phosphorous compound is present in an amount of about 1.0% by weight based on 100% styrene polymer.
16. 16. The polymer composition according to claim 14, characterized in that the phosphorous compound is present in an amount of about 2.0% by weight based on 100% styrene polymer.
17. The polymer composition according to any of the preceding claims, characterized in that the polymer composition has a closed cell content of at least 90 percent according to ASTM D-2856
18. 18. A foamable gel for making the foamed latex ignition according to any of the preceding claims, characterized in that it comprises the styrene polymer a) and the ignition retardant formulation b) specified in the preceding claims; the optional flow promoter specified in claims 2 to 4; and a blowing agent.
19. 19. The foamable gel according to claim 1 8, characterized in that the blowing agent is a blowing agent mixture comprising up to 50% water.
20. 20. The foamable gel according to claim 18 or 10, characterized in that the blowing agent is a blowing agent mixture comprising up to 80% of HFC-134a (1,1,1-tetrafluoroethane)