MXPA01000101A - Polyphosphate salt of a 1,3,5-triazine compound with a high degree of condensation and its use as flame retardant in polymer compositions - Google Patents

Abstract

Salt of a 1,3,5-triazine compound with polyphosphoric acid with a virtually linear structure, with the number average degree of condensation n being higher than 20, the content of the 1,3,5-triazine compound being higher than 1.1 mole per mole of phosphorus atom and the pH of a 10%slurry in water being higher than 4.5. Further, a process for the preparation of the polyphosphate salt of a 1,3, 5-triazine compound with a number average degree of condensation n that is higher than 20, by converting a 1,3,5-triazine compound with orthophosphoric acid at room temperature into the phosphate of the 1,3,5-triazine compound, after which this salt is converted at elevatedtemperature into a polyphosphate of the 1,3,5-triazine compound, and further flame retardant polymer compositions comprising the polyphosphate salt of a 1,3,5-triazine compound with a number average degree of condensation n higher than 20.

Description

POLIFOSPHATE SALT OF A COMPOUND OF 1,3,5-TRIAZINE WITH A HIGH DEGREE OF CONDENSATION, A PROCEDURE FOR ITS PREPARATION AND USE AS A RETARDANT OF FLAME IN POLYMER COMPOSITIONS DESCRIPTIVE MEMORY The invention relates to a polyphosphate salt of a 1,3-triazine compound, a process for its preparation, and use of the resulting salt as a flame retardant in polymer compositions. The polyphosphate of a 1,3-triazine compound can be represented by the general formula: wherein M represents a 1,3-triazine compound and n is an integer greater than 3 which represents a measure of the average degree of condensation in number. For high values of n, the polyphosphate of a 1,3-triazine compound can be better represented by the formula (MHP03) n. Theoretically, the structure is substantially linear if the M / P ratio (triazine / phosphorus) is almost exactly 1.0. Similarly, if the M / P ratio is less than 1, this indicates that the product includes some entanglement and, if the M / P ratio is less than 0.4, this indicates that the degree of entanglement is sufficient for the product to form a network structure. Melamine polyphosphate and a process for preparing melamine polyphosphate are described, inter alia, in WO 97/44377. According to this reference, melamine polyphosphate having a solubility of 0.01 to 0.10 g per 100 ml of water at 25 ° C, a pH between 2.5 and 4.5, and a molar ratio of melamine / phosphorus between 1.0 and 1.1, can be obtained as a 10% by weight aqueous suspension at 25 ° C. WO 97/44377 also describes a two-step process for preparing the described melamine polyphosphate suspension. In the first step the melamine, urea, and an aqueous orthophosphoric acid solution (containing at least 40% by weight orthophosphoric acid), are mixed to produce a reaction mixture with a melamine / orthophosphoric acid molar ratio between 1.0 and 1.5. moles and a urea / orthophosphoric acid molar ratio between 0.1 and 1.5 at a temperature between 0 and 140 ° C. The resulting reaction mixture is subsequently stirred at a temperature between 0 and 140 ° C and dehydrated to produce a pulverized product comprising a double salt of orthophosphoric acid with melamine and urea. This pulverized product is subsequently heated between 240 and 340 ° C and maintained at this temperature scale for 0.1 and 30 hours while avoiding agglomeration to obtain melamine polyphosphate. A drawback of melamine polyphosphate having a melamine / phosphorus molar ratio between 1.0 and 1.1 such as those prepared in accordance with WO 97/44377, in its general instability to be used as a flame retardant in polymers. This is particularly the case for polymers such as nylons and polyesters that are typically processed at elevated temperatures, at which temperatures the salts do not exhibit sufficient thermal stability. In addition, the pH of said salts is relatively low, a property that tends to adversely affect the mechanical properties of the polymer such as impact resistance, tensile strength, and resistance to rupture. However, it has been found that the salts of 1,3,5-triazine compounds with polyphosphoric acid having n-values greater than 20, and preferably greater than 40, and M / P ratios of at least 1.1, and preferably at minus 1.2, do not present these drawbacks when combined with polymers. Further, according to the present invention, the value n of said salts should generally be between 20 and 200, preferably 40 and 150, and the M / P ratio should be between 1.1 and 2.0, preferably between 1.2 and 1.8. In addition, the pH gives an aqueous suspension at 10% by weight of salts prepared according to the present invention will generally be greater than 4.5 and preferably at least 5.0. The mentioned pH value is determined by introducing 25 g of the salt and 225 g of pure water, at 25 ° C in a 300 ml beaker, stirring the resulting aqueous suspension for 30 minutes, and then measuring the pH. The value of n mentioned, the average degree of condensation in number, can be determined by means of NMR with solid P31. From J.R. van Wazer, C.F. Callis, J. Shoolery and R. Jones, J. Am. Chem. Soc, 78, 5715, 1956, in number of neighboring phosphate groups is known to provide a unique "chemical shift", which makes it possible to clearly distinguish between orthophosphates, pyrophosphates and polyphosphates. In addition, a process for the preparation of the desired polyphosphate salt of a 1,3,5-triazine compound having an n-value of at least 20, and preferably at least 40, and an M / P ratio of at least 1.1. This process involves the conversion of a 1,3-triazine compound with orthophosphoric acid into its orthophosphate salt, followed by dehydration and heat treatment to convert the orthophosphate salt into a polyphosphate of the compound of 3,5- triazine. This heat treatment is preferably carried out at a temperature of at least 300 ° C, and preferably at least 310 ° C. In addition to the orthophosphates of compounds 1, 3,5-triazine, other 1,3,5-triazine phosphates can be used, including, for example, a mixture of orthophosphates and pyrophosphates. The orthophosphate of the 1,3-triazine compound can be prepared in a variety of procedures. The preferred process involves adding a 1,3-triazine compound to an aqueous solution of orthophosphoric acid. An alternative procedure involves adding orthophosphoric acid to an aqueous suspension of the 1,3-triazine compound. The process according to the present invention can also be carried out in the presence of a catalyst. As a result, the final product has better electrical properties as indicated by the comparative alignment index (CTI) known from the literature, measured in accordance with the IEC 695-2-1 standard. Although any hydroxide can be used as a catalyst, alkali metal hydroxides, and alkaline earth metal hydroxides are preferred. The boric acid salts, for example zinc, borate, can also be used as a catalyst. If used, the amount of the catalyst used will generally be between 0.1% by weight and 10% by weight. The reaction time required for satisfactory production of the desired polyphosphate of the 1,3,5-triazine compound is generally at least 2 minutes, and more generally at least 5 minutes, and generally less than 24 hours. A polyphosphate of the 1,3,5-triazine derivative according to the present invention must contain less than 1% by weight of water-soluble material, and preferably less than 0.1% by weight. This low content of water-soluble material indicates that the product consists mainly of the desired polyphosphate. It has also been found that the polyphosphate salts of 1,3,5-triazine compounds according to the present invention are particularly suitable as flame retardants in polymer compositions. When used in this way, the amount of flame retardant used in a polymer composition generally ranges from 15 to 45% by weight, and more generally from 20 to 40% by weight. It is believed that the adaptability of these particular 1, 3,5-triazine polyphosphate salts of compounds gives ____________________! ___ as a result the increased thermal stability and the increased pH achieved by compounds according to the present invention when compared to other flame retardants, such as halogen compounds, melamine, etc. The flame retardant polymer compositions according to the present invention preferably comprise the following components: 35-55% by weight of polymer 15-45% by weight of polyphosphate salt of a compound of 1,3,5-triazine with a degree Condensation average in number n greater than 20 0-50% by weight of fiber for reinforcement 0-20% by weight of carbon-forming compound 0-10% of a catalyst that promotes the formation of carbon The compounds of 1, 3, Suitable 5-triazine include 2,4,6-tramin-1, 3,5-triazine (melamine), melam, melem, melon, amelin, amelide, 2-ureidomelamine, acetoguanamine, benzoguanamine, diaminphenyltriazine or mixtures thereof. Melamine, melam, melem, melon or mixtures thereof are preferred, and melamine in particular is preferred. The polymers and polymer compositions to which polyphosphate salts of 1,3,5-triazine compounds prepared in accordance with the present invention are to be added, to improve the properties of the flame retardant include the following: 1.- Polymers of mono and diolefins, for example, polypropylene (PP), polyisobutylene, polybutylene-1, polymethylpentene-1, polyisoprene or polybutadiene; polyethylenes (optionally entangled) including, for example, high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), or mixtures of these polymers. 2. Copolymers of mono and diolefins, which optionally include other vinyl monomers such as, for example, ethylene-propylene copolymers, linear low density polyethylene, and mixtures thereof with low density polyethylene, as well as ethylene terpolymers with propylene and a diene such as hexadiene, dicyclopentadiene or ethylideneomer; furthermore, mixtures of said copolymers with the polymers named in number 1 such as, for example, polypropylene / ethylene-propylene copolymers. 3.- Polystyrene, poly- (p-methyl-styrene), poly- (α-methylstyrene) and copolymers of styrene or α-methylstyrene with dienes or acrylic derivatives, such as, for example, styrene-butadiene, styrene-acrylonitrile , styrene-alkyl methacrylate, styrene-butadiene-alkyl acrylate, styrene-anhydridemaleic acid and styrene-acrylonitrile-methylacrylate. 4.- Polyphenylene oxide and polyphenylene sulfide and their mixtures with styrene polymers or with polyamides.

. - Polyurethanes derived from polyethers, polyesters and polybutadiene with terminal hydroxy groups on the one hand and aliphatic or aromatic polyisocyanates on the other, as well as their precursors. 6.- Polyamides and copolyamides derived from diamines and dicarboxylic acids and / or corresponding aminocarboxylic acids or lactams, such as polyamide 4, polyamide 6, polyamide 6/6, 6/10, 6/9, 6/12, 4 / 6, 66/6, 6/66, polyamide 11, polyamide 12, aromatic polyamides based on an aromatic diamine and adipic acid; polyamides prepared from hexamethylenediamine and iso- and / or terephthalic acid and optionally an elastomer as a modifier, for example poly-2,4,4-trimethylhexamethylene-trichlolamide, poly-m-phenylene isophthalamide. 7. Polyesters derived from dicarboxylic acids and dialcohols and / or hydroxycarboxylic acids or the corresponding lactones such as polyethylene terephthalate, polybutylene terephthalate, poly-1,4-dimethylolcyclohexane terephthalate and polyhydroxybenzoates. 8. Thermosetting resins include, for example, unsaturated polyesters, saturated polyesters, alkyd resins, polyacrylate or polyether or compassions containing one or more of these polymers and a crosslinking agent. If reinforcing materials are used in a polymer composition according to the invention, their content may vary within wide limits depending to a large extent on the desired or necessary level of one or more mechanical properties, as well as on aesthetic, manufacturing or economic In general, however, the amount of reinforcing materials will be between 5 and 50% by weight, and more preferably, between 15 and 35% by weight. The reinforcement material can be chosen from the group of inorganic reinforcing materials such as, for example, mica, clay or glass fibers; or aramid fibers and / or carbon fibers, or combinations thereof. However, in general, glass fibers are preferred. The flame retardant action of the polyphosphate salt of a 1,3-triazine compound can be improved by the presence of a compound with a synergistic effect for the flame retardant, particularly a so-called carbon-forming compound, optionally in the combination with a catalyst that promotes the formation of carbon. In general, the presence of a carbon-forming compound, with or without a catalyst, makes it possible to reduce the content of polyphosphate derived from triazine without reducing the flame retardant properties of the resulting polymer composition. A number of substances are known to enhance the flame retardant action of the triazine-derived polyphosphate and can be included in the polymer composition as a carbon-forming compound. These substances include, for example, phenol resins, epoxy resins, melamine resins, alkyd resins, allyl resins, unsaturated polyester resins, silicon resins, urethane resins, acrylate resins, starch, glucose, and compounds with at least two hydroxy groups. Examples of compounds with at least two hydroxy groups include various alcohols such as pentaerythritol, dipentaerythritol, tripentaerythritol, and mixtures thereof. The concentration of said carbon-forming compounds in the polymer composition is typically less than 20% by weight, and preferably between 5 and 15% by weight. A variety of catalysts can also be incorporated to promote carbon formation. These catalysts include, among others, metal salts of tungstic acid, acid oxides in tungsten complex with a metalloid, tin oxide salts, ammonium sulfamate and / or its dimers. The metal salts of tungstic acid are preferably alkali metal salts, and in particular sodium tungstate. It is understood that an acid oxide in tungsten complex with a metalloid is an acid oxide complex formed from a metalloid such as silicon or phosphorus and tungsten. The amount of catalyst used in the polymer composition is generally 0.1-5% by weight, and preferably 0.1-2.5% by weight. If polyolefins such as polyethylene, polypropylene, or mixtures thereof are used in the flame retardant polymer composition, it is also preferred to include a carbon-forming compound and / or a catalyst to promote carbon formation. The flame retardant action of the polyphosphate salt of the 1,3-triazine compound can also be improved by the addition of a second flame retardant component. In principle any other known flame retardant can be used as the second component _-_ --- _____ 1É ____ flame retardant. Examples include antimony oxides, for example antimony trioxide; alkaline earth metal oxides, for example magnesium oxide; other metal oxides, for example alumina, silica, zinc oxide, iron oxide and manganese oxide; metal hydroxides, for example, magnesium hydroxide and aluminum hydroxide; metal borates, for example hydrated or unhydrated zinc borate; and phosphorus-containing compounds. Examples of phosphorus-containing compounds are zinc phosphate, ammonium phosphate, ammonium pyrophosphate, ammonium polyphosphate, ethylenediamine phosphate, piperazine phosphate, piperazine pyrophosphate, melamine phosphate, dimelamine phosphate, melamine pyrophosphate, guanidine phosphate. , dicyanodiamide phosphate and / or urea phosphate. Phosphonates and phosphate esters can also be used. Their content may vary within wide limits but generally does not exceed the content of polyphosphate derived from triazine. The polymer composition can also contain the other customary additives, for example stabilizers, release agents, flow agents, dispersants, colorants and / or pigments, and amounts that are generally applicable. The additive content of the polymer compositions is generally selected to ensure that the desired properties remain within acceptable limits, limits which, of course, will vary with the composition of the polymer and the intended application (s). The polymer compositions according to the present invention can be prepared using most conventional techniques, including dry mixing of all or a number of components in a stirring mixer followed by melting in a molten material mixer, for example a Brabender mixer, a screw extruder, or preferably, a twin screw extruder. The components of the polymer composition of the invention can be fed together in the throat of the extruder or can be fed into the extruder individually or in sub-combinations through a plurality of inlets. If the fiberglass reinforcement has to be included in the composition, it is preferably avoided to add the glass fibers to the composition in the throat of the extruder to minimize breakage of the glass fiber. A number of components, for example dyes, stabilizers, and other additives, can be added to the polymer as a masterbatch. The resulting polymer composition can then be processed into a variety of semi-manufactured products and finished products using a variety of techniques known to those skilled in the art, for example injection molding. The invention will be clarified in relation to the following examples: Comparative Example A 50 liter reactor equipped with a stirrer was charged with 29. 25 liters of pure water. While stirring, 8,619 kg of orthophosphoric acid was added at room temperature (85% by weight of H3PO). Due to the exothermic reaction, the temperature of the phosphoric acid solution ____________ &______ diluted was raised, and kept at 50 ° C for 10 minutes. While still stirring, 9,419 kg of melamine (to avoid lumping) was slowly added to the solution. After the melamine was added, the reactor pressure was reduced and the temperature increased to evaporate the water and obtain a product with a moisture content of less than 0.1% by weight. The resulting melamine phosphate, with an M / P ratio of 1.0, was subsequently heated to a temperature of 310 ° C and converted to melamine phosphate with an M / P ratio of 0.94. A 10% by weight aqueous suspension of the resulting melamine polyphosphate at 25 ° C had a pH of less than 5. A mixture consisting of 25% by weight of the resulting melamine polyphosphate, 20% by weight of the glass fiber (PPG) 3545 of PPG Industries) and 55% by weight of polyamide 6.6 (Bayer Durethan A31) was prepared and extruded as a granulated material. The test bars were subsequently prepared from the resulting granular material and the following properties were determined: Flame retardation: V-1 in accordance with UL-94 VB 1.6 mm. Tension resistance: 140 MPa in accordance with ISO 527. Elongation at break: 1.5% in accordance with ISO 527. Slot impact value, Charpy: 37 KJ / m2 in accordance with ISO 179-1 E-A / U. Modulus of elasticity: 11 GPa in accordance with ISO 527.

EXAMPLE A 50 liter reactor equipped with an agitator was charged with 29.25 liters of pure water. While stirring, 8,619 kg of orthophosphoric acid was added at room temperature (85% by weight of H3PO4) to the water. Due to the exothermic reaction, the temperature of the diluted phosphoric acid solution was raised and maintained at 50 ° C for 10 minutes. While it was still stirring, 12,245 kg of melamine were subsequently added slowly (to avoid the formation of lumps). After the melamine was added, the reactor pressure was slowly reduced and the temperature increased to evaporate the water and obtain a product with a moisture content of less than 0.1% by weight. The resulting melamine phosphate, with an M / P ratio of 1.3, was subsequently heated to a temperature of 310 ° C and converted to a melamine polyphosphate with an M / P ratio of 1.26. A 10% by weight aqueous solution of polyphosphate salt had a pH greater than 5. A mixture consisting of 25% by weight of the resulting melamine polyphosphate according to the present invention, 20% by weight of glass fiber (PPG) 3545 by PPG Industries) and 55% by weight of polyamide 6.6 (Bayer Durethan A31) was prepared and extruded as a granulated material. As with the polymer composition prepared in the comparative example, the test bars were subsequently made from the granulated material and the following properties were determined: Flame delay: V-0 in accordance with UL-94 VB 1.6 mm. Resistance to tension: 153 MPa in accordance with ISO 527. Elongation at break: 2.1% in accordance with ISO 527. Value of impact of groove, Charpy: 48 KJ / m2 in accordance 1 E-A / U. Eslasticity module: 12 GPa in accordance with ISO 527. ______ i _____ É_l ___ i

Claims (10)

NOVELTY OF THE INVENTION CLAIMS

1. - Polyphosphate salt of a 1,3-triazine compound, characterized in that the average degree of condensation in number of n is greater than 20, the melamine content is greater than 1.1 mole of melamine per mole of phosphorus atom and the pH of a 10% suspension of salt in water is greater than or equal to 5.

2. The polyphosphate salt according to claim 1, further characterized in that the average degree of condensation in number of n is greater than 40.

3. The polyphosphate salt of the 1,3-triazine compound, further characterized in that the melamine content is greater than 1.2 moles of melamine per mole of phosphorus atom.

4. Process for the preparation of polyphosphate salt of a compound of 3,5-triazine with an average degree of condensation in number of n that is greater than 20 when converting a compound of 1,3,5-triazine with orthophosphoric acid at room temperature in the phosphate of compound 1, 3,5-triazine, after which this salt is converted into the polyphosphate of the 1,3-triazine compound, by means of a heat treatment.

5. The process according to claim 4, further characterized in that the phosphate of the compound of 1,3,5-triazine is ! ________________ becomes a polyphosphate of the compound 1, 3,5-triazine at a temperature greater than or equal to 300 ° C.

6. The process according to claim 5, further characterized in that the phosphate of the 1,3-triazine compound is converted to the polyphosphate of the 1,3-triazine compound at a temperature greater than or equal to 310 ° C.

7. The process according to claims 4-6, further characterized in that an average degree of condensation in number greater than 40 is obtained.

8. The composition of flame retardant polymer, further characterized in that the polyphosphate of a compound of 1, 3,5-triazine with an average degree of condensation in number greater than 20, the melamine content is greater than 1.1 moles of melamine per mole of phosphorus atom and the pH of a 10% suspension of the salt in water is greater than or equal to 5, it is used as a flame retardant component.

9. The flame retardant polymer composition according to claim 8, further characterized in that melamine, melam, melem, melon or mixtures of these are used as 1,3-triazine compounds.

10. The flame retardant polymer composition according to claim 9, further characterized in that the melamine is used as the 1,3-triazine compound.