Flame retardant additive and applications thereof

Abstract

Flame retardant additives are disclosed for enhancing the flame retardant properties of synthetic polymers. The flame retardant additives can be obtained using diphenyl chlorophosphate as a raw material. The flame retardant additives preferably comprise at least one hydroxyl group.

Description

[0001] Flame retardant additive and applications thereof

[0002] The invention relates to flame retardant additives for enhancing the flame retardant properties of synthetic polymers. The invention also relates to applications of these flame retardant additives in the production of synthetic polymers, e.g. in the production of polymer foams.

[0003] The use of flame retardants in synthetic polymers is known. US2019 / 0233574A1 describes the use of flame retardant additives in the production of polyisocyanurate foams. Triethyl phosphate (TEP) andtris(2-chloroisopropyl) phosphate (TCPP) are listed in US2019 / 0233574A1 as flame retardant additives that can be used in the production of polyisocyanurate foams.

[0004] W02020 / 076529A1 discloses rigid polyurethane foam formulations comprising tris(2-chloroisopropyl) phosphate (TCPP) as flame retardant additive.

[0005] W02020 / 076539A1 discloses rigid polyurethane foam formulations comprising tris(2-chloroisopropyl) phosphate (TCPP) or triethyl phosphate (TEP) as flame retardant additive.

[0006] Health concerns have been raised for triethyl phosphate (TEP) and tris(2-chloroisopropyl) phosphate (TCPP). The health concerns may restrict the use of these flame retardants additives.

[0007] Therefore, it is an object of the invention to provide alternative flame retardant additives that overcome problems of the prior art.

[0008] It is an object of the invention to provide alternative flame retardant additives that when used in thermally insulation foams provide better properties of the insulation foams.The object of the invention is - according to the first aspect of the invention - achieved by a flame retardant additive for enhancing the flame retardant properties of synthetic polymers. The flame retardant additive of the first aspect of the invention is a flame retardant additive according to any one of the following four options.

[0009] According to the first option, the flame retardant additive comprises or consists of an alkyl diaryl phosphate comprising at least one - preferably primary - hydroxyl group on the alkyl group.

[0010] According to the second option, the flame retardant additive comprises or consists of an isocyanurate based alkyl diaryl phosphate, comprising at least one and preferably two phosphate groups, optionally wherein the alkyl group comprises a - preferably primary - hydroxyl group. Such embodiments have the benefit that thermal stability of synthetic polymers comprising the flame retardant additive is increased, leading to further increased flame retardancy and increased strength of the synthetic polymer.

[0011] In preferred embodiments according to the second option, the isocyanurate group is substituted with one or more substituents, wherein at least one - and preferably at least two - of the substituents comprise a hydroxyl group, preferably a primary hydroxyl group.

[0012] According to the third option the flame retardant additive comprises or consists of an alkyl diaryl phosphoramidate comprising at least one hydroxyl group on the alkyl group, wherein the alkyl diaryl phosphoramidate is represented by formula 1 :

[0013]

[0014] wherein n represents an integer higher than or equal to 1. The integer n can preferably be 1, 2 or 3.R1 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted independently from R2 and R3.

[0015] R2 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted independently from R1 and R2.

[0016] R3 is selected from alkyl, alkenyl, alkynyl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S. N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be substituted; independently from R1 and R2.

[0017] Each of the substitutions Rl, R2, R3 can be made independently from each other.

[0018] Each of the two phenyl groups of the alkyl diaryl phosphoramidate can be substituted more than once, with the same or with different substituents.The alkyl group of the alkyl diaryl phosphoramidate of formula 1 preferably comprises at least one primary hydroxyl group, and more preferably at least two primary hydroxyl groups.

[0019] According to the fourth option, the flame retardant additive comprises or consists an alkyl diaryl phosphoramidate represented by formula 2:

[0020]

[0021] wherein n and m independently represent an integer higher than or equal to 1. The integers n and m preferably equal 1, 2 or 3. More preferably, n and m equal 1.

[0022] R1 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted independently from R2, R3 and R4.

[0023] R2 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted independently from Rl, R3 and R4.R3 is selected from alkyl, alkenyl, alkynyl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S. N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be substituted; independently from Rl, R2 and R4.

[0024] R4 is selected from alkyl, alkenyl, alkynyl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S. N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be substituted; independently from Rl, R2 and R3.

[0025] In a preferred embodiment, R3 is equal to R4.

[0026] Each of the two phenyl groups of the molecule represented by formula 2 can be substituted more than once, with the same or with different substituents.

[0027] The flame retardants of the different options of the invention have the benefit that when used in an insulation foam formulation, the insulation foam produced has better insulation properties (as expressed in a lower heat conductivity value, lambda, expressed in W / (m*K)). Furthermore, the flame retardant is less prone to leaching, resulting in a higher durability of the flame retardant properties of the insulation foam and in even lower toxicity of the synthetic polymer comprising the flame retardant additive. The flame retardant additives according to the invention comprising hydroxyl groups provide the opportunity for being incorporated via covalent bonds in a polymer matrix, improving the durability of the flame retardant effect provided to the synthetic polymers. Such benefit is more present when the flame retardant additive comprises primary hydroxylgroups, even more when the molecule of the flame retardant additive comprises more than one primary hydroxyl group.

[0028] The flame retardant additives of the four options can all be made using diphenyl chlorophosphate as a raw material, whether or not with substitutions on one or on both phenyl groups of the diphenyl chlorophosphate.

[0029] A preferred example of a flame retardant additive according to the fourth option is provided by the following formula 3 :

[0030]

[0031] This flame retardant has the benefit that the flame retardant additive molecule comprises two primary hydroxyl groups, which can form covalent bonds in the production of synthetic polymers. The hydroxyl groups can e.g. react with isocyanate groups in the production of polyurethane or polyisocyanurate. The flame retardant additive of formula 3 is even less prone to leaching when incorporated in a synthetic polymer.

[0032] Preferred embodiments of isocyanurate based alkyl diaryl phosphates according to the second option, comprising at least one and preferably two phosphate groups are given by the following formulas:

[0033]

[0034] u .

[0035] 5 R1 and R2 can be independently from each other selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more ofthe carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted.

[0036] Each of the phenyl groups of the isocyanurate based alkyl diaryl phosphates can be substituted more than once, with the same or with different substituents.

[0037] In more preferred examples of isocyanurate based alkyl diaryl phosphates, R1 and R2 equal H. Therefore, preferred examples of isocyanurate based alkyl diaryl phosphates are provided by the molecules of the following formulas:

[0038]

[0039] (ormua ) <

[0040]

[0041] (formula 12)

[0042] In preferred embodiments wherein the flame retardant additive comprises or consists of an isocyanurate based alkyl diaryl phosphate, the isocyanurate group comprises a substituent comprising at least one - preferably primary - hydroxyl group. More preferably, the isocyanurate group comprises two substituents, preferably each comprising at least one - preferably primary - hydroxyl group.

[0043] In embodiments of the flame retardant additive according to the first option, the alkyl diaryl phosphate is a molecule or molecules represented by formula 7:

[0044]

[0045] wherein n represents an integer higher than or equal to 1. Preferred values for n are 1, 2 and 3.

[0046] R1 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenylgroup, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted.

[0047] R2 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted.

[0048] R1 and R2 can be identical or can be different.

[0049] R3 is selected from alkyl, alkenyl, alkynyl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S. N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be substituted.

[0050] The substituents Rl, R2 and R3 can be selected independently from each other.

[0051] Each of the phenyl groups of the alkyl diaryl phosphate of formula 7 can be substituted more than once with substituents different from H, with the same or with different substituents.

[0052] In preferred embodiments from the flame retardant additive of formula 7, Rl and R2 equal H.

[0053] In preferred embodiments from the flame retardant additive of formula 7, Rl and R2 equal H; and R3 is a Cl, C2, C3 or C4 alkyl.In preferred embodiments of the flame retardant additive of the first option, the alkyl diaryl phosphate is a molecule or molecules represented by formula 8:

[0054]

[0055] an integer higher than or equal to 1. Preferred values for n are 1, 2 and 3.

[0056] R1 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted.

[0057] R2 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted.

[0058] R1 and R2 can be identical or can be different.

[0059] R3 is selected from alkyl, alkenyl, alkynyl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be replaced bya heteroatom independently selected from O, S. N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be substituted.

[0060] The substituents Rl, R2 and R3 can be selected independently from each other.

[0061] Each of the phenyl groups of the alkyl diaryl phosphate of formula 8 can be substituted more than once with substituents different from H, with the same or with different substituents.

[0062] In preferred embodiments from the flame retardant additive of formula 8, Rl and R2 equal H.

[0063] In preferred embodiments from the flame retardant additive of formula 8, Rl and R2 equal H; and R3 is a Cl, C2, C3 or C4 alkyl.

[0064] A more preferred flame retardant additive according to the invention comprises or consists of a molecule or combination of molecules represented by formula 9:

[0065]

[0066] wherein n represents an integer equal to or greater than 1, preferably between 1 and 9, more preferably between 1 and 6, even more preferably between 1 and 3.

[0067] Rl is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenylgroup, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted.

[0068] R2 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted.

[0069] R1 and R2 can be identical or can be different.

[0070] Each of the phenyl groups of the alkyl diaryl phosphate represented by formula 9 can comprise more than one substituent, which may be the same or different.

[0071] In more preferred embodiments of flame retardant additives according to formula 9, n equals 1, 2 or 3; and preferably R1 and R2 equal H

[0072] The embodiment with n = 1 (and more preferably with R1 and R2 equal to H) is particularly preferred, as the flame retardant can be manufactured using mono ethylene glycol (MEG) as a raw material.

[0073] The embodiment with n = 2 (and more preferably with R1 and R2 equal to H) is particularly preferred, as the flame retardant can be manufactured using di ethylene glycol (DEG) as a raw material.

[0074] The second aspect of the invention is the use of a flame retardant additive as in any embodiment of flame retardant additive of the first aspect of the invention in the production of a synthetic polymer.In a preferred embodiment, the flame retardant additive is used in the production of polyurethane, polyisocyanurate, polyvinyl chloride, ethyl vinyl acetate (EVA), polyester or phenolics, e.g. phenolic foams.

[0075] Such use is beneficial, as hydroxyl groups of the flame retardant additives can react in the production of the synthetic polymer, resulting in bonds - preferably covalent bonds - between the hydroxyl groups of the flame retardant additive and the polymer molecules. It is a benefit that leaching of the flame retardant additive is prevented, resulting in more durable flame retardant properties of the synthetic polymer.

[0076] The use of the flame retardant additives of the first aspect of the invention in the production of polyurethane (e.g. in the production of polyurethane foams) and in the production of polyisocyanurate (e.g. in the production of polyisocyanurate foams) is particularly preferred, as the hydroxyl group(s) of the flame retardant additive can react in the same way as the hydroxyl groups of the polyol used in the production of the polyurethane or polyisocyanurate with the isocyanate being used. Consequently, the flame retardant additive is bonded via covalent bonds in the polyurethane or polyisocyanurate polymer which is produced. The bonds avoid the flame retardant additive from leaching from the synthetic polymer that has been made.

[0077] The third aspect of the invention is a polyol composition for use in the production of polyurethane or polyisocyanurate, wherein the polyol composition comprises at least one polyol, a flame retardant additive as in any embodiment of the first aspect of the invention; and optionally at least one blowing agent, optionally at least a surfactant (preferably a silicone surfactant) and optionally a catalyst.

[0078] The polyol composition can be used in the production of polyurethane or polyisocyanurate for providing the polyurethane or polyisocyanurate with excellent and durable flame retardant properties. Insulation foams made with such polyols have shown to have excellent insulation properties, as evidenced by low values for the heat transfer coefficient (lambda value, as measured according to ISO 8301:1991), expressed in W / (m*K).The polyol can be a polyether polyol or a polyester polyol, or combinations thereof.

[0079] The fourth aspect of the invention is a polyurethane foam formulation or a polyisocyanurate foam formulation comprising

[0080] - a polyol, preferably a polyester polyol or a polyether polyol or combinations thereof; - a flame retardant additive as in any embodiment of the first aspect of the invention; - an isocyanate or a polyisocyanate component, preferably comprising at least one polyisocyanate,

[0081] - at least a blowing agent,

[0082] - at least a surfactant, preferably at least a silicone surfactant,

[0083] - at least a catalyst.

[0084] A preferred polyurethane or the polyisocyanurate foam formulation is characterized in that it comprises a polyol composition. The polyol composition comprises the polyol and the flame retardant additive; and optionally the at least a blowing agent, optionally the at least a surfactant, and optionally the at least a catalyst. In such embodiments, the polyol composition is preferably a polyol composition as in the third aspect of the invention.

[0085] The polyol composition and the isocyanate or the polyisocyanate component can be mixed, preferably just before the foam formation process.

[0086] Adding the flame retardant additive to the polyol composition - and not to the isocyanate or the polyisocyanate - has the benefit that blending the foam formulation for performing the foam production process is facilitated. Furthermore, adding the flame retardant additive to the isocyanate or the polyisocyanate could create premature chemical reactions between the flame retardant additive and the isocyanate or the polyisocyanate.

[0087] The polyisocyanate can comprise or consist of polymeric methylene diphenyl diisocyanate (pMDI).

[0088] The isocyanate can comprise of consist of toluene diisocyanate (TDI).The fifth aspect of the invention is a polyurethane foam or a polyisocyanurate foam obtained from a foam formulation according to the fourth aspect of the invention.

[0089] A preferred polyurethane foam or a preferred polyisocyanurate foam is characterized in that the foam formulation comprises a flame retardant additive as in any embodiment of the first aspect of the invention, wherein the flame retardant additive comprises at least one - preferably primary - hydroxyl group, wherein the at least one hydroxyl group has reacted with the isocyanate or the polyisocyanate in the foam formation process when reacting the polyol composition with the isocyanate or the polyisocyanate.

[0090] The reaction of the at least one hydroxyl group with the isocyanate or the polyisocyanate can result in the formation of a urethane group linking the flame retardant additive in the polyurethane foam or in the polyisocyanurate foam. As a consequence, the flame retardant additive is less prone to leaching from the polyurethane foam or from the polyisocyanurate foam.

[0091] A flame retardant additive comprising at least one primary hydroxyl group in the alkyl group is preferred, as primary hydroxyl groups have high reactivity with isocyanate groups, higher reactivity than secondary hydroxyl groups. Therefore, the presence of primary hydroxyl groups results in foam products wherein the flame retardant additive is even less prone to leaching.

[0092] The sixth aspect of the invention is a thermal insulation product comprising a foam obtained by reacting a polyurethane foam formulation or a polyisocyanurate foam formulation according to any embodiment of the fourth aspect of the invention; and / or comprising a polyurethane foam or a polyisocyanurate foam as in any embodiment of the fifth aspect of the invention.

[0093] Preferably, the flame retardant additive is added to the polyol, preferably with other additives such as surfactants and catalysts; and the isocyanate or the polyisocyanate is then added for the chemical reaction between the polyol on the one hand and on the otherhand the isocyanate or the polyisocyanate to take place in the process of forming the foam product.

[0094] The invention will now be illustrated by a number of non-limiting examples. A number of polyisocyanurate laboratory foam samples have been prepared with a flame retardant additive according to the invention, tested and compared with reference samples. The reference sample has for each of the samples tested been produced and tested at the same time and under the same conditions as the specific sample that has been made and tested, in order to avoid influences from other more uncontrollable parameters in the comparative test results.

[0095] A first example of a flame retardant additive according to the invention has been made by providing 1 equivalent diphenyl chlorophosphate (CAS 2524-64-3), 1 equivalent diethylene glycol (DEG, CAS 111-46-6) and 1.5 equivalents triethylamine (CAS 121-44-8).

[0096] A mixture of the diethylene glycol, the triethylamine and chloroform (CAS 67-66-3) as solvent is placed in a water / ice bath. The concentration of diethylene glycol in the mixture is between 1 and 1.5 mol / 1. The diphenyl chlorophosphate is added dropwise to the mixture. The temperature of the solution is kept below 40°C, by controlling the rate of the dropwise addition of the diphenyl chlorophosphate. After complete addition of the diphenyl chlorophosphate, the mixture is stirred during 1 hour in the water / ice bath. Stirring is then performed during an additional 16 hours at room temperature. The formed white solid, which is triethylamine hydrochloride salt, is filtered off. The mixture is washed with a 0.1 mol sodium hydroxide solution until the acid value is below 3 mg KOH / gram. The solvent (chloroform) is removed, either via distillation or via rotary evaporation, and the flame retardant additive is obtained as provided by the chemical structure (yield 80%) :

[0097]

[0098] (formula 13)

[0099] The flame retardant additive is a low viscous slightly orange liquid.

[0100] The method described in the first example is a non-exhaustive example of how to produce the flame retardant obtained in the first example.

[0101] Using the flame retardant (FR) additive of the first example, a rigid isocyanurate foam panel has been produced. To 100 parts by weight of a polyester polyol, 15 parts by weight of the flame retardant additive have been added. Other additives - known in the production of rigid isocyanurate foam panels have been added: catalysts and surfactants.

[0102] 190 parts by weight of a polymeric methylene diphenyl diisocyanate (pMDI) is added, and the rigid isocyanurate foam has been made. The properties of the rigid isocyanurate foam prepared with the flame retardant additive of the first example have been compared with a reference sample made in the similar way but adding 15 parts by weight of tris(2-chloroisopropyl) phosphate (TCPP) to the 100 parts of polyol instead of the flame retardant additive obtained in the first example.

[0103] The results are listed in the table. The table lists the density, the thermal insulation value lambda (measured according to ISO 8301:1991), the compression strength in the foam rise direction (Compr R) and in counter foam rise direction (Compr CR) and the initial flame height (B2 initial) measured according to DIN 4102-1:1998 “Fire behaviour of building materials and elements - Classification of building materials - Requirements and testing”.

[0104]

[0105] The results show that rigid isocyanurate foams of good quality can be made with the flame retardant additive of the first example.

[0106] A second example of a flame retardant additive according to the invention has been made by providing 1 equivalent diphenyl chlorophosphate (CAS 2524-64-3), 1 equivalent monoethylene glycol (MEG, CAS 107-21-1) and 1.5 equivalents triethylamine (CAS 121-44-8).

[0107] A mixture of the monoethylene glycol, the triethylamine and chloroform (CAS 67-66-3) as solvent is placed in a water / ice bath. The concentration of monoethylene glycol in the mixture is between 1 and 1.5 mol / 1. The diphenyl chlorophosphate is added dropwise to the mixture. The temperature is kept below 40°C, by controlling the rate of the dropwise addition of the diphenyl chlorophosphate. After complete addition of the diphenyl chlorophosphate, the mixture is stirred during 1 hour in the water / ice bath. Stirring is then performed during an additional 16 hours at room temperature. During the reaction, the mixture turned green / teal. The mixture obtained is washed with a 0.1 mol sodium hydroxide solution until the acid value is below 3 mg KOH / gram. The color changed to brown during and remained brown after the extraction. Following this, the mixture is washed with a brine solution. Lastly, the solvent (chloroform) is removed either via distillation or rotary evaporation and the flame retardant additive is obtained provided by the chemical structure, as a brown colored liquid (yield 84.4%):

[0108]

[0109] (formula 14)

[0110] Using the flame retardant (FR) additive of the second example, a rigid isocyanurate foam panel has been produced. To 100 parts by weight of a polyester polyol, 15 parts by weight of the flame retardant additive of the second example have been added. Other additives - known in the production of rigid isocyanurate foam panels have been added: catalysts and surfactants. 190 parts by weight of a polymeric methylene diphenyl diisocyanate (pMDI) is added, and the rigid isocyanurate foam has been made. The properties of the rigid isocyanurate foam prepared with the flame retardant additive of the second example have been compared with a reference sample made in the similar way but adding 15 parts by weight of tris(2-chloroisopropyl) phosphate (TCPP) to the 100 parts of polyol instead of the flame retardant additive obtained in the first example.

[0111] The results are listed in the table. The table lists the density, thermal insulation value lambda, the compression strength in the foam rise direction (Compr R) and in counter foam rise direction (Compr CR) and the initial flame height (B2 initial) measured according to DIN 4102-1:1998 “Fire behaviour of building materials and elements -Classification of building materials - Requirements and testing”.

[0112]

[0113] The results show that rigid isocyanurate foams of good quality can be made with the flame retardant additive of the second example.

[0114] A third example of a flame retardant additive according to the invention has been made by providing 2 equivalents diphenyl chlorophosphate (CAS 2524-64-3), 1 equivalent triethanolamine (CAS 102-71-6) and 3 equivalents triethylamine (CAS 121-44-8). A mixture of the triethanolamine, triethylamine and chloroform (CAS 67-66-3) as solvent is placed in a water / ice bath. The concentration of triethanolamine in the mixture is between 0.5 and 1 mol / 1. The diphenyl chlorophosphate is added dropwise to the mixture. The temperature is kept below 40°C, by controlling the rate of the dropwise addition of the diphenyl chlorophosphate. After complete addition of the diphenyl chlorophosphate, the mixture is stirred during 1 hour in the water / ice bath. Stirring is the performed during an additional 16 hours at room temperature. The formed tri ethylamine hydrochloride salt (a white solid) is filtered off. The remaining product is washed with a 0.1 mol sodium hydroxide solution until the acid value is below 3 mg KOH / gram. The solvent (chloroform) is removed, either via distillation or rotary evaporation; and the flame retardant additive is obtained comprising molecules as shown in the chemical structure of formula 15, as a highly viscous dark brown liquid (yield 83.5 %):

[0115]

[0116] (formula 15)

[0117] Using the flame retardant (FR) additive of the third example, a rigid isocyanurate foam panel has been produced. To 100 parts by weight of a polyester polyol, 15 parts by weight of the flame retardant additive of the second example have been added. Other additives - known in the production of rigid isocyanurate foam panels have been added: catalysts and surfactants. 190 parts by weight of a polymeric methylene diphenyl diisocyanate(pMDI) is added, and the rigid isocyanurate foam has been made. The properties of the rigid isocyanurate foam prepared with the flame retardant additive of the third example have been compared with a reference sample made in the similar way but adding 15 parts by weight of tris(2-chloroisopropyl) phosphate (TCPP) to the 100 parts of polyol instead of the flame retardant additive obtained in the first example.

[0118] The results are listed in the table. The table lists the density, thermal insulation value lambda, the compression strength in the foam rise direction (Compr R) and in counter foam rise direction (Compr CR) and the initial flame height (B2 initial) measured according to DIN 4102-1:1998 “Fire behaviour of building materials and elements -Classification of building materials - Requirements and testing”.

[0119]

[0120] The results show that rigid isocyanurate foams of sufficient quality can be made with the flame retardant additive of the second example.

[0121] A fourth example of a flame retardant additive according to the invention has been made by providing 2 equivalents diphenyl chlorophosphate (CAS 2524-64-3), 1 equivalent (tris (2-hydroxyethyl) isocyanurate (THEIC, CAS 839-90-7) and 3 equivalents tri ethylamine (CAS 121-44-8).

[0122] A suspension of the THEIC (as THEIC did not fully dissolve in THF), the triethylamine and tetrahydrofuran (THF, CAS 109-99-6) is made. The concentration of THEIC in the suspension is between 0.5 and 1 mol / 1. The diphenyl chlorophosphate is added dropwise to the mixture. After complete addition, the mixture is heated to reflux for 6 hours. Thereaction mixture is cooled and the formed triethylamine hydrochloride salt (a white solid) is filtered off. Additional triethylamine is added to reduce the acid value and capture any residual formed HC1. The resulting formed white solid is filtered off once more. Following this, the solvent and remaining triethylamine is removed (either via distillation or rotary evaporation). A highly viscous transparent liquid (yield 78.4 %) is obtained as flame retardant additive, comprising molecules having the molecular structure shown in formula 16:

[0123]

[0124] (formula 16)

[0125] A fifth example of a flame retardant additive according to the invention has been made by providing 1 equivalent diphenyl chlorophosphate (CAS 2524-64-3), 1 equivalent (tris (2 -hydroxyethyl) isocyanurate (THEIC, CAS 839-90-7) and 1.5 equivalents triethylamine (CAS 121-44-8).

[0126] A suspension of the THEIC (as it does not fully dissolve in THF), triethylamine and tetrahydrofuran (THF, CAS 109-99-6) is made. The concentration of THEIC in the suspension is between 0.5 and 1 mol / 1. The diphenyl chlorophosphate is added dropwise to the mixture. After complete addition, the mixture is heated to reflux for 6 hours. The reaction mixture is cooled and the formed triethylamine hydrochloride salt (a white solid) is filtered off. Additional triethylamine is added to reduce the acid value and capture any residual formed HC1. The resulting formed white solid is filtered off once more. Following this, the solvent and remaining triethylamine is removed (either via distillationor rotary evaporation). A highly viscous transparent liquid (yield 70.2 %) is obtained as flame retardant additive, having molecular structure:

[0127]

[0128] (formula 17)

[0129] The examples show the use of the flame retardant additives in the production of polyisocyanurate. However, the same flame retardant additives can be used in the production of other synthetic polymers, e.g. in the production of polyurethane as well as in the production of polyvinyl chloride, ethyl vinyl acetate (EVA), polyester and phenolics, e.g. in the production of phenolic foams.

[0130] The present invention is in no way limited to the embodiments described as examples, on the contrary it can be realized in various forms and dimensions, without leaving the scope of the invention.

Claims

Claims1 Flame retardant additive for enhancing the flame retardant properties of synthetic polymers, wherein the flame retardant additive is a flame retardant additive according to anyone of the following four options:- option 1: an alkyl diaryl phosphate comprising at least one - preferably primary - hydroxyl group on the alkyl group;- option 2: an isocyanurate based alkyl diaryl phosphate, comprising at least one and preferably two phosphate groups, optionally wherein the alkyl group comprises at least one - preferably primary - hydroxyl group;- option 3: an alkyl diaryl phosphoramidate comprising at least one - preferably primary - hydroxyl group on the alkyl group, wherein the alkyl diaryl phosphoramidate is represented by formula 1 :wherein n represents an integer higher than or equal to 1; preferably wherein n equals 1, 2 or 3;wherein R1 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted independently from R2 and R3;wherein R2 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl orpolymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted independently from R1 and R2;wherein R3 is selected from alkyl, alkenyl, alkynyl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S. N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be substituted; independently from R1 and R2;- option 4: an alkyl diaryl phosphoramidate represented by formula 2:wherein n and m independently represent an integer higher than or equal to 1 ; preferably wherein the integers n and m are equal 1, 2 or 3;wherein R1 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted independently from R2, R3 and R4;wherein R2 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or thearylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted independently from Rl, R3 and R4;wherein R3 is selected from alkyl, alkenyl, alkynyl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S. N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be substituted; independently from Rl, R2 and R4;wherein R4 is selected from alkyl, alkenyl, alkynyl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S. N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be substituted; independently from Rl, R2 and R3.2.- A flame retardant additive according to claim 1, characterized in that the flame retardant additive is represented by formula 3:3.- Flame retardant additive as in claim 1, characterized in that the flame retardant additive is an isocyanurate based alkyl diaryl phosphate comprising at least one and preferably two phosphate groups, and that the flame retardant additive is a molecule or a combination of molecules according to the following formulas:; 5wherein R1 and R2 can be independently from each other selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted.4.- Flame retardant additive as in claim 3, characterized in that R1 equals H and that R2 equals H.5.- Flame retardant additive as in claims 1, 3 or 4, characterized in that the flame retardant additive comprises or consists of an isocyanurate based alkyl diaryl phosphate and that the isocyanurate group comprises a substituent comprising at least one - preferably primary - hydroxyl group.6.- A flame retardant additive as in claim 1, characterized in that the flame retardant additive is an alkyl diaryl phosphate comprising at least one - preferably primary - hydroxyl group on the alkyl group, wherein the alkyl diaryl phosphate is a molecule or a combination of molecules represented by formula 7:wherein n represents an integer higher than or equal to 1, preferably n equals 1, 2 or 3; wherein R1 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkylgroup may be substituted;wherein R2 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted;wherein R3 is selected from alkyl, alkenyl, alkynyl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S. N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be substituted; independently from R1 and R2.7.- A flame retardant additive as in claim 1, characterized in that the flame retardant additive is an alkyl diaryl phosphate comprising at least one - preferably primary -hydroxyl group on the alkyl group, wherein the alkyl diaryl phosphate is a molecule or a combination of molecules represented by a molecule or molecules represented by formula 8:wherein n represents an integer higher than or equal to 1, preferably n equals 1, 2 or 3; wherein R1 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, thealkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted;wherein R2 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted;wherein R3 is selected from alkyl, alkenyl, alkynyl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S. N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the cycloalkyl group or the arylalkyl group may be substituted; independently from R1 and R2.8.- A flame retardant additive as in claim 6, characterized in that the flame retardant additive is a molecule or combination of molecules represented by formula 9:wherein n represents an integer from 1 to 9, more preferably 1 to 6 most preferably 1 to 3;wherein R1 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkylgroup may be substituted;wherein R2 is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, arylalkyl or polymeric groups, wherein one or wherein one or more of the carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be replaced by a heteroatom independently selected from O, S, N and Si and / or may comprise a functional group; and / or wherein the alkyl group, the alkenyl group, the alkynyl group, the aryl group, the cycloalkyl group or the arylalkyl group may be substituted.9.- Use of a flame retardant additive as in any of the preceding claims in the production of a synthetic polymer, preferably in the production of polyurethane, polyisocyanurate, polyvinyl chloride, ethyl vinyl acetate (EVA), polyester or phenolics, e.g. in the production of phenolic foams.10.- Polyol composition for use in the production of polyurethane or polyisocyanurate, wherein the polyol composition comprises at least one polyol, and a flame retardant additive as in any of the preceding claims 1 - 8; and optionally a surfactant, and optionally at least one blowing agent.11.- A polyurethane foam formulation or a polyisocyanurate foam formulation comprising- a polyol, preferably a polyester polyol or a polyether polyol or combinations thereof; - a flame retardant additive as in any of the preceding claims 1 - 8;- an isocyanate or polyisocyanate component, preferably comprising at least one polyisocyanate;- at least a blowing agent;- at least a surfactant, preferably at least a silicone surfactant;- at least a catalyst.12.- A polyurethane foam formulation or a polyisocyanurate foam formulation as in claim 11, characterized in that the foam composition comprises a polyol composition,wherein the polyol composition comprises the polyol and the flame retardant additive; preferably wherein the polyol composition is a polyol composition as in claim 10.13.- A polyurethane foam or a polyisocyanurate foam obtained from a foam formulation according to claim 11 or 12.14.- A polyurethane foam or a polyisocyanurate foam as in claim 13, characterized in that the foam formulation comprises a flame retardant additive as in any of the preceding claims 1 - 8, wherein the flame retardant additive comprises at least one - preferably primary - hydroxyl group, wherein the at least one hydroxyl group has reacted with the isocyanate or the polyisocyanate in the foam formation process when reacting the polyol composition with the isocyanate or with the polyisocyanate.15.- A thermal insulation product comprising a foam obtained by reacting a polyurethane foam formulation or a polyisocyanurate foam formulation as in any of the preceding claims 11 - 12; and / or comprising a polyurethane foam or a polyisocyanurate foam as in claims 13 or 14.

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