Flame-retardant polyurethane and uses thereof

Abstract

A flame-retardant polyurethane obtained by reacting a polyol and an isocyanate in the presence of a flame retardant comprising a phosphinic acid ester of formula (I): wherein R1 is a hydrocarbyl group selected from C1-C12 alkyl groups and C6-C20 aryl groups; and wherein R2 and R3, identical or different, independently represent H or a C1-C12 alkyl group.

Description

(19) State Intellectual Property Office (12) Invention Patent Application (10) Application Publication Number (43) Application Publication Date (21) Application Number 202480034487.7 (22) Application Date 2024.03.25 (66) Domestic Priority Data 202310599807.0 2023.05.25 CN PCT / CN2023 / 115548 2023.08.29 CN (85) PCT International Application Entering National Phase Date 2025.11.24 (86) PCT International Application Application Data PCT / CN2024 / 083608 2024.03.25 (87) PCT International Application Publication Data WO2024 / 239791 EN 2024.11.28 (71) Applicant Clariant International Ltd. Address: Switzerland Applicant: F. F. Klaussen, O. Hornstein, Zhang Hua, Wang Xintai, Li Zhou, Liu Hu (74) Patent Agency: China Council for the Promotion of International Trade Patent & Trademark Office Co., Ltd. 11038 Patent Attorney: Mi Xia (51) Int.Cl. C07F 9 / 30 (2006.01) C08K 5 / 5313 (2006.01) (54) Invention Title: Flame-retardant polyurethane and its use (57) Abstract: A flame-retardant polyurethane obtained by reacting a polyol and an isocyanate in the presence of a flame retardant comprising a phosphonate of formula (I): wherein R1 is a hydrocarbon group selected from C1-C12 alkyl and C6-C20 aryl; and wherein R2 and R3, the same or different, independently represent H or C1-C12 alkyl. Claims (2 pages), Description (12 pages), CN 121219302 A, 2025.12.26, CN 1 21 21 93 02 A 1. A flame-retardant polyurethane obtained by reacting a polyol and an isocyanate in the presence of a flame retardant comprising a phosphonate of formula (I): wherein R1 is a hydrocarbon group selected from C1-C12 alkyl and C6-C20 aryl; and wherein R2 and R3, whether the same or different, independently represent H or C1-C12 alkyl. 2. The flame-retardant polyurethane according to claim 1, wherein R1 is selected from C1-C6 alkyl, preferably from C2-C4 alkyl. 3. The flame-retardant polyurethane according to claim 1 or 2, wherein R2 and R3 are not both H. 4. The flame-retardant polyurethane according to claim 3, wherein one of R2 and R3 is H or an ethyl, and the other is a C1-C6 alkyl. 5. The flame-retardant polyurethane of claim 3, wherein one of R2 and R3 is methyl, and the other is H or C1-C4 alkyl. 6. The flame-retardant polyurethane of claim 1, wherein R1 is ethyl, one of R2 and R3 is methyl, and the other is ethyl. 7. The flame-retardant polyurethane of claim 1, wherein R1 is butyl.8. One of R2 and R3 is methyl, and the other is H. 9. The flame-retardant polyurethane of claim 1, wherein R1 is butyl, and one of R2 and R3 is methyl, and the other is butyl. 10. A flame-retardant polyurethane foam obtained by reacting a polyol and an isocyanate in the presence of a flame retardant as defined in any one of claims 1-8, further in the presence of a foaming agent, a foaming catalyst, and a foam stabilizer. 11. The flame-retardant polyurethane foam of claim 9, wherein the polyurethane foam is a flexible foam. 12. The flame-retardant polyurethane foam of claim 9, wherein the polyurethane foam is a rigid foam. 12. Use of flame-retardant polyurethane according to any one of claims 1-8 or flame-retardant polyurethane foam according to any one of claims 9-11 in the manufacture of door liners, headliners, seat covers, high-resilience foam seats, high-resilience foam mattresses, rigid foam insulation panels, viscoelastic foam mattresses, potting foams for battery applications, microcellular foam sealants or gaskets, durable elastomer wheels or tires, automotive suspension bushings, electro-encapsulation compounds, high-performance adhesives, surface coatings or sealants, synthetic fibers, carpet backings, or rigid plastic parts or hoses. 13. A method of manufacturing flame-retardant polyurethane according to any one of claims 1-8, comprising: preparing a mixture comprising a polyol and the flame retardant; and adding an isocyanate compound to the mixture. 14. Use of a phosphonate of formula (I) as a flame retardant for polyurethane, wherein R1 is a hydrocarbon group selected from C1-C12 alkyl and C6-C20 aryl; and wherein R2 and R3, whether the same or different, independently represent H or C1-C12 alkyl. 15. A flame-retardant polyurethane composition comprising a phosphonate of formula (I) as a flame retardant. Claim 1 / 2 page 2 CN 121219302 A Wherein R1 is a hydrocarbon group selected from C1-C12 alkyl and C6-C20 aryl; and wherein R2 and R3, the same or different, independently represent H or C1-C12 alkyl. Claim 2 / 2 page 3 CN 121219302 A Flame-retardant polyurethane and its use Technical Field

[0001] The present invention relates to flame-retardant polyurethanes containing specific types of phosphonate flame retardants, methods of manufacturing thereof, and their use in industry. Background Art

[0002] To achieve the flame retardancy required for industrial applications, flame-retardant modified polyurethanes are typically combined with at least one type of flame retardant substance. In these applications, liquid flame retardants are often preferred over their solid counterparts. This preference stems from several advantageous properties: compared to solid flame retardants, liquid flame retardants can be more easily and uniformly dispersed or even dissolved within the polymer during blending, thereby providing a consistent flame-retardant effect overall. In addition, liquid flame retardants can often be processed at lower temperatures than solids.This mitigates the potential polymer degradation problem associated with higher temperatures. Because of their larger surface area for interaction, these liquid additives can be incorporated into resin mixtures more quickly than solids. Furthermore, liquid flame retardants are generally easier to manipulate during blending with polyols, allowing for precise dosage control and seamless integration with polymer formulations.

[0003] One popular liquid flame retardant widely used in industry is TCPP (tris(1-chloro-2-propyl) phosphate), which is frequently incorporated into polyurethane foams in consumer products, household insulation, and electronics. However, despite providing effective flame retardancy, TCPP has been found to leach into the environment over time, causing negative toxicological and ecotoxicological effects due to its halogenated nature. Furthermore, the leaching of TCPP flame retardants leads to a decrease in overall flame retardant effectiveness over time.

[0004] US 9,631,144 B2 describes a different liquid flame retardant composition comprising one or more halogenated flame retardants obtained by reacting tetrabromobisphenol A with epichlorohydrin, resulting in a brominated epoxide. This particular liquid flame retardant is said to provide stable incorporation into rigid polyurethane foam and exhibit good flame retardancy. However, it is worth noting that in the operational examples provided in US 9 631 144 B2, the brominated epoxide is obtained in the form of a resin with a high softening point, which necessitates further processing at high temperatures. Furthermore, the resulting liquid flame retardant composition is characterized in particular by a high bromine content of at least 30% by weight.

[0005] Given the growing concern about the use of halogenated flame retardants due to environmental protection, efforts have been made to find alternative halogen-free liquid flame retardants for polymers and polymer foams.

[0006] US 4 458 035 A describes a low polyphosphate flame retardant for polyurethane foam, and the phosphate has the following formula (1), wherein

[0007] n is 0 to 10,

[0008] R is a C1-C10 (halogenated) alkyl group and

[0009] R1 and R2 are hydrogen atoms or C1-C10 (halogenated) alkyl groups.

[0010] Specification 1 / 12 pages 4 CN 121219302 A

[0011] US 7 288 577 B1 describes a blend of two different phosphate ester flame retardants for polyurethane, which is basically composed of the following substances:

[0012] (a) 50% by weight of butylated triphenyl phosphate of the blend, and

[0013] (b) 50% by weight of poly(ethyl ethylene oxy) phosphate of the blend.

[0014] Although the above patent publications may have mentioned some effective liquid phosphorus-based flame retardants, it has been found that some of them are prone to hydrolysis under humid conditions, which in turn leads to adverse effects on the polymerization process or the final polymer properties. In particular, it is known that the acid formed by hydrolysis may deactivate the polymerization catalyst during the foaming process.And further break the covalent bonds in the polymer foam product, thereby destroying the desired 3-D foam network.

[0015] Several liquid phosphorus-based flame retardant products are available, including Antiblaze® 1045 (from Albemarle), a cyclic phosphonate compound commonly used in polymers such as PET and PBT. The chemical structure of this cyclic phosphonate is shown by the following formula (2).

[0016]

[0017] Antiblaze® 1045 has a high viscosity, typically 500,000 mPa·s or higher at 25°C. Therefore, its effective use may involve careful impregnation onto a carrier material or meticulous application as an aqueous solution to the surface of polymer fibers. In the latter case, subsequent heating is required to soften the fibers and dissolve the cyclic phosphonate to obtain the desired results. Summary of the Invention

[0018] Summary of the Invention

[0019] The object of the present invention is to provide a novel halogen-free flame retardant for polyurethane, particularly polyurethane foam. The halogen-free flame retardant is in liquid form at room temperature and under conventional polyurethane manufacturing conditions, has a suitably low viscosity for easy processing and handling, exhibits excellent hydrolytic stability even under humid conditions, and provides polyurethane materials with equal or enhanced flame retardancy levels compared to existing commercial standards.

[0020] The present invention aims to provide a flame-retardant polyurethane, particularly polyurethane foam, which achieves superior flame retardancy efficiency by incorporating the above-mentioned halogen-free flame retardant.

[0021] The present invention provides the use of phosphonates of formula (I) as flame retardants for polyurethanes

[0022]

[0023] wherein R1 is a hydrocarbon group selected from C1-C12 alkyl and C6-C20 aryl;

[0024] and wherein R2 and R3, the same or different, independently represent H or C1-C12 alkyl. Specification 2 / 12 Page 5 CN 121219302 A

[0025] The present invention further provides a flame-retardant polyurethane obtained by reacting a polyol and an isocyanate in the presence of a flame retardant comprising a phosphonate of formula (I).

[0026] Detailed Description of the Invention

[0027] Unless otherwise stated, the term “hydrocarbon” as used herein means an aliphatic, aromatic, or alicyclic group, which may be saturated or unsaturated, straight or branched, and optionally substituted with heteroatoms (e.g., O, N, S).

[0028] Preferably, R1 is selected from C1-C6 alkyl, more preferably from C2-C4 alkyl.

[0029] Also preferably, R2 and R3 are not both H.

[0030] In a preferred embodiment of the invention, one of R2 and R3 is H or ethyl, and the other is C1-C6 alkyl.

[0031] In another preferred embodiment of the invention, one of R2 and R3 is methyl, and the other is H or C1-C4 alkyl.

[0032] In a particularly preferred embodiment, R1 is ethyl,One of R2 and R3 is methyl, and the other is ethyl.

[0033] In another particularly preferred embodiment, R1 is butyl, one of R2 and R3 is methyl, and the other is H.

[0034] In yet another particularly preferred embodiment, R1 is butyl, one of R2 and R3 is methyl, and the other is butyl.

[0035] Due to its chemical properties, the phosphonate flame retardant according to the invention is in liquid form at room temperature and under conventional polyurethane manufacturing conditions. Advantageously, the liquid form of the phosphonate flame retardant is further characterized by a low viscosity of less than 100 mPa·s at a temperature of 25°C, preferably less than 50 mPa·s, more preferably less than 10 mPa·s. The viscosity can be measured by DIN 51398. As mentioned above, the advantageous property of low viscosity may play an important role in the practical application of liquid flame retardants used in the manufacture of flame-retardant polyurethanes. The use of viscous liquid flame retardants presents challenges because they typically require heating of containers, feed lines, and discharge lines involved in the storage or transport of the liquid. Furthermore, uniformly incorporating high-viscosity flame retardant liquids into polymer compositions often requires additional effort, especially in large-scale industrial processes used for the production of chemicals in large quantities.

[0036] Phosphinates of Formula (I) can be prepared by various methods. One approach is to react α-monoolefins with (alkyl)phosphinates in the presence of a free radical generator, as described in US 39 14 345 A, EP 23 73 666 A1, US 87 35 477 B2, and EP 23 67 834 A1.

[0037]

[0038] Phosphinates of Formula (I) can also be prepared from their corresponding phosphites via a catalytic rearrangement reaction. For example, one corresponding phosphite has the following structure (II):

[0039]

[0040] As illustrated in Synthesis Example 1, this preparation method can be achieved in two steps. In the first step, a corresponding phosphite of the desired hypophosphite product is produced as an intermediate, and in the second step, this intermediate is subjected to a catalytic rearrangement reaction to obtain the hypophosphite of formula (I). Alternatively, if the corresponding phosphite is readily available from the chemical market, the preparation method can be simplified to a one-step reaction.

[0041] The rearrangement catalyst in this preparation method can be an iodine-containing catalyst and a Lewis acid catalyst, such as iodine, alkyl iodide (especially potassium iodide), as described in CN 104693238A. Alternatively, the rearrangement catalyst can be sodium iodide as described in CN 109400643A.

[0042] Advantageously, the rearrangement catalyst can be a small organic molecule sulfonate.More advantageously selected are diethyl sulfate, ethyl ethanesulfonate, methyl p-toluenesulfonate, ethyl p-toluenesulfonate, methyl p-chlorobenzenesulfonate, and ethyl p-chlorobenzenesulfonate. The benefits of using a small organic molecule sulfonate rearrangement catalyst in this preparation method include cost-effectiveness and simplified catalyst recovery.

[0043] When R2 or R3 is H, the hypophosphite of formula (I) can be prepared, as illustrated in Synthetic Example 2, by reacting an alkyl dichlorophosphine with an alcohol at a moderate temperature. This reaction, known as alcoholysis, is known to result in partial oxidation of the phosphine, leading to the formation of the corresponding alkyl hypophosphite, while simultaneously generating a P-H bond.

[0044] An exemplary example of this chemistry is given in CN 113493478A, in which methyl dichlorophosphine is reacted with n-butanol at room temperature. This reaction produces n-butyl methyl hypophosphite as the desired product, with hydrogen chloride and n-butyl chloride forming as byproducts.

[0045] The present invention also provides a flame-retardant polymer obtained by reacting monomers under polymerization conditions in the presence of a flame retardant containing a phosphonate of formula (I).

[0046] The flame-retardant polyurethane (PUR) of the present invention is a polyurethane composition containing a phosphonate of formula (I) as a flame retardant. In one embodiment of the polyurethane composition, the phosphonate of formula (I) is present in an amount of 0.5% to 30% by weight relative to the weight of the polyurethane. Preferably, the phosphonate of formula (I) is present in an amount of 0.5% to 20% by weight relative to the weight of the polyurethane.

[0047] The flame-retardant polyurethane of the present invention is preferably obtained by reacting a polyol and an isocyanate in the presence of a flame retardant containing a phosphonate of formula (I), optionally in the presence of a polymerization catalyst. Suitable polymerization catalysts for the production of flame-retardant polyurethanes can be selected from aliphatic tertiary amines (e.g., triethylamine, tetramethylbutanediamine), alicyclic tertiary amines (e.g., 1,4-diaza(2,2,2)bicyclooctane), aliphatic amino ethers (e.g., dimethylaminoethyl ether and N,N,N-trimethyl-N-hydroxyethyl-diaminoethyl ether), alicyclic amino ethers (e.g., N-ethylmorpholine), aliphatic amidines, alicyclic amidines, ureas, urea derivatives (e.g., aminoalkyl ureas, see, for example, EP-A 0 176 013, particularly (3-dimethylaminopropylamine)urea), and tin catalysts (e.g., dibutyltin oxide, dibutyltin dilaurate, tin octoate).

[0048] A significant advantage of using phosphonates of formula (I) as flame retardants for polyurethanes is their high compatibility with polyols (i.e., an essential starting material for polyurethanes). The phosphonates of formula (I) can be readily dissolved in polyols, thereby forming a homogeneous solution that remains stable over a prolonged period during storage or transportation. This homogeneous solution serves as a beneficial starting material for polymerization, thereby ensuring that the resulting polyurethane product has a uniformly distributed flame retardancy.

[0049] The present invention provides a method for manufacturing flame-retardant polyurethane.It includes preparing a mixture comprising a polyol and a flame retardant, said flame retardant comprising a phosphonate of formula (I); and adding an isocyanate compound to said mixture.

[0050] For the purposes of this invention, the term "polyol" refers to a compound having at least two hydrogen atoms capable of reacting with an isocyanate. These are compounds having amino, thio, or carboxyl groups, preferably having hydroxyl groups, particularly compounds with 2 to 8 hydroxyl groups.

[0051] Suitable polyols for the present invention include those with a molecular weight (Mw) of 400 to 10,000, particularly those with a molecular weight of 1,000 to 6,000, preferably 2,000 to 6,000, and are generally dihydroxy to octahydroxy, preferably dihydroxy to hexahydroxy polyethers or polyesters, or polycarbonates or polyesteramides, as those known per se for the production of homogeneous or porous polyurethanes, and as described, for example, in DE-A 28 32 253.

[0052] Preferred polyester polyols are obtained by polycondensation of polyols such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, methylpentanediol, 1,6-hexanediol, trimethylolpropane, glycerol, pentaerythritol, diglycerol, glucose, and / or sorbitols (see page 4 / 12 of CN 121219302 A for specifications) with diacids such as oxalic acid, malonic acid, succinic acid, tartaric acid, adipic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, and / or terephthalic acid. These polyester polyols can be used alone or in combination.

[0053] For the production of thermosetting flame-retardant polyurethanes, another group of preferred polyester polyols are those having two, three, or four hydroxyl groups, including ethylene glycol, propylene glycol, trimethylolpropane, and pentaerythritol.

[0054] Preferred polyether polyols include, but are not limited to, triols such as glycerol, trimethylolethane (i.e., 1,1,1-tri(hydroxymethyl)ethane) and trimethylolpropane (i.e., 1,1,1-tri(hydroxymethyl)propane); tetraols such as pentaerythritol; pentaneols such as glucose; hexaols such as dipentaerythritol and sorbitol; or alkoxylated derivatives of all the above polyols, such as preferably ethoxylated and propoxylated derivatives thereof.

[0055] Particularly preferred polyether polyols are polyoxypropylene triols.

[0056] For the purposes of this invention, other suitable polyols include those with low molecular weights of 30 to 400, preferably compounds having hydroxyl and / or amino groups and acting as chain extenders or crosslinking agents. These compounds typically have 2 to 8, preferably 2 to 4, hydrogen atoms capable of reacting with isocyanates.

[0057] Suitable isocyanates for producing the flame-retardant polyurethane of the present invention may be selected from, for example, aliphatic, alicyclic, aryliphatic, aromatic or heterocyclic polyisocyanates (see, for example, W. Siefken, in Justus Liebigs Annalen der Chemie, 562, pp. 75-136).For example, those of the formula Q(NCO)r, where r is 2 to 4, preferably 2 to 3, and Q is an aliphatic hydrocarbon group having 2 to 18 carbon atoms, preferably 6 to 10 carbon atoms, an alicyclic hydrocarbon group having 4 to 15 carbon atoms, preferably 5 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 15 carbon atoms, preferably 6 to 13 carbon atoms, or an aryl-aliphatic hydrocarbon group having 8 to 15 carbon atoms, preferably 8 to 13 carbon atoms.

[0058] Suitable polyisocyanates for the present invention are aromatic, alicyclic and / or aliphatic polyisocyanates and mixtures thereof having at least two isocyanate groups. Preferred are aromatic polyisocyanates, such as toluene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, phenyl dimethylene diisocyanate, tris(4-isocyanate phenyl)methane and polymethylene-polyphenyl diisocyanate; alicyclic polyisocyanates, such as diphenylmethane diisocyanate and toluene diisocyanate; alicyclic polyisocyanates and hexamethylene diisocyanate, isophorone diisocyanate, dimeryl diisocyanate, 1,1-methylene bis(4-isocyanate cyclohexane-4,4'-diisocyanate dicyclohexylmethane (met) and mixtures of isomers, 1,4-cyclohexyl diisocyanate and lysine diisocyanate and mixtures thereof.

[0059] Typically, industrially available polyisocyanates, such as 2,4- and 2,6-toluene diisocyanates, and diphenylmethane isocyanate (MDI) or their polymeric forms (pMDI), are particularly preferred.

[0060] For the purposes of this invention, the flame-retardant polyurethane can be a linear PUR, for example produced by diols and diisocyanates, or a crosslinked PUR, for example produced by converting a triisocyanate-diisocyanate mixture with a triol-diol mixture. The properties of the flame-retardant polyurethane can vary over a wide range. Depending on the degree of crosslinking and / or the isocyanate or OH component used, thermosetting materials, thermoplastic materials, or elastomers are obtained.

[0061] The flame-retardant polyurethane of this invention can be used as a flexible or rigid foam, or as a molding compound for molding, as a casting resin (isocyanate resin), as an elastic fiber (textile), as a polyurethane coating, and as a flame-retardant polyurethane foam for use as a polyurethane adhesive.

[0062] The present invention also provides a flame-retardant polyurethane foam, which is obtained by reacting a polyol and an isocyanate in the presence of a flame retardant comprising a phosphonate of formula (I), and further in the presence of a foaming agent, a foaming catalyst, a foam stabilizer, and optionally other additives.

[0063] In a preferred embodiment of the present invention, the flame-retardant polyurethane foam of the present invention is a flexible foam.

[0064] In another preferred embodiment of the present invention, the flame-retardant polyurethane foam of the present invention is a rigid foam. Specification 5 / 12 pages 8 CN 121219302 A

[0065] For the purposes of the present invention,The term "foaming agent" refers to a substance capable of providing gas and producing foam with a porous (cellular) structure in a polyol-isocyanate reaction. Any conventional foaming agent used in the production of polyurethane foam is applicable here, including physical and chemical foaming agents. Examples of physical foaming agents include butane and carbon dioxide, which expand under reduced pressure, as well as short-chain (C5-C6) aliphatic molecules such as pentane or cyclopentane, and various hydrofluoroolefins such as 1,3,3,3-tetrafluoropropylene, which are low-boiling liquids. Examples of chemical foaming agents include water and carboxylic acids, which release gas upon reaction with isocyanates. A particularly preferred foaming agent is water.

[0066] For the purposes of this invention, suitable foaming catalysts for producing the flame-retardant polyurethane foam of this invention are preferably selected from amine catalysts (e.g., tertiary amines) and organometallic compounds (e.g., stannous octoate, stannous acetate, dibutyltin diacetate, etc.).

[0067] For the purposes of this invention, suitable foam stabilizers for producing the flame-retardant polyurethane foam can be any conventional stabilizers used to control and stabilize polyurethane foam. As a preferred example, the stabilizer may be selected from silicone surfactants.

[0068] To produce the flame-retardant polyurethane foam according to the invention, other additives, including fillers, pigments, light stabilizers, and processing aids, may be added to the reactant mixture.

[0069] The invention also relates to the use of the flame-retardant polyurethane or flame-retardant polyurethane foam as described above in the manufacture of door liners, headliners, seat covers, high-resilience foam seats, high-resilience foam mattresses, rigid foam insulation panels, viscoelastic foam mattresses, potting foams for battery applications, microcellular foam sealants and gaskets, durable elastomer wheels and tires, automotive suspension bushings, electro-encapsulation compounds, high-performance adhesives, surface coatings and sealants, synthetic fibers, carpet padding, rigid plastic parts, and hoses.

[0070] The present invention also relates to the use of flame-retardant polyurethane or flame-retardant polyurethane foam in the manufacture of electrical switch components, components in automotive construction, electrical engineering or electronic devices, printed circuit boards, prepreg preforms, potting compounds for electronic components, for marine and rotor blade construction, for outdoor GFRP applications, household and sanitary applications, and in engineering materials. Detailed Description

[0071] Examples

[0072] The invention is described in more detail and specifically below with reference to examples; however, these examples are not intended to limit the invention.

[0073] 1. Components used:

[0074] Flame retardant:

[0075] FR-1: Ethyl (methyl)phosphine ethyl ester (MEPE) product of Synthesis Example 1

[0076] FR-2: Butyl methylphosphine butyl ester product of Synthesis Example 2

[0077] FR-3: Butyl (methyl)phosphine butyl ester (MUPU) product of Synthesis Example 3

[0078] Ref-1: Fyrol® PCF obtained from ICL Industrial Products,TCPP (tris(1-chloro-2-propyl) phosphate), a halophosphate ester

[0079] Ref-2: Exolit® OP 550 from Clariant International Ltd, a halogen-free polymeric phosphorus polyol specifically designed for flexible polyurethane foams, which is a phosphate ester with hydroxyalkyl groups.

[0080] Polyols:

[0081] Polyether polyols (P1): Arcol® 1104 or 1108 from Covestro AG, medium molecular weight polyoxypropylene triol with an OH value of 56 mg KOH / g

[0082] Polyester polyols (P2): Terate® HT 5510, aromatic polyester polyol from Stepan Company, its specification page 6 / 12, 9 CN 121219302 A, with a hydroxyl value of 257 mg KOH / g

[0083] Polymerization catalysts:

[0084] Cat 1: Kosmos® EF from Evonik Industries, stannous catalyst

[0085] Cat 2: Kosmos® 29 from Evonik Industries, stannous octoate catalyst

[0086] Cat 3: Niax® from Momentive Performance Materials Inc. A1, Amine catalyst based on bis(2-dimethylaminoethyl) ether

[0087] Cat 4: Tegoamin® 33 from Evonik Industries, an amine catalyst based on triethylenediamine

[0088] Cat 5: JEFFCAT® ZF-10 from Huntsman, an amine catalyst based on N,N,N'-trimethyl-N'-hydroxyethyl bisaminoethyl ether

[0089] Cat 6: Polycat 5 from Evonik Industries, an amine catalyst based on bis(2-dimethylaminoethyl) methylamine

[0090] Cat 7: Kosmos 75 MEG from Evonik Industries, a foam catalyst based on low-viscosity potassium octanoate

[0091] Foam stabilizer:

[0092] S1: Tegostab® B 8232 from Evonik Industries, an organosilicon surfactant

[0093] S2: Tegostab® B from Evonik Industries 8522, Organosilicon Surfactant

[0094] TDI (Toluene Diisocyanate):

[0095] T80: Desmodur® T80, 2,4- and 2,6-toluene diisocyanate, obtained from Covestro AG.80 / 20 isomer mixture

[0096] MDI (diphenylmethane diisocyanate):

[0097] MDI1: Desmodur® 44 V 70 L from Covestro AG, which is a mixture of diphenylmethane-4,4'-diisocyanate (MDI) with isomers and homologues with higher functionality (PMDI).

[0098] 2. Synthesis examples of flame retardants FR-1, FR-2 and FR-3 of the present invention

[0099] 2.1 Synthesis example 1: Preparation of FR-1

[0100] Step 1: Preparation of diethyl methylphosphonite

[0101] In a 25 L autoclave equipped with a thermometer and a condenser, a mixture of 5280 g of petroleum ether, 413 g of anhydrous ethanol and 1100 g of triethylamine was added. The reaction system was purged three times with nitrogen, and then 501 g of a solution of methyldichlorophosphane was added dropwise at 25°C. Once the addition was complete, the temperature was maintained at 25°C for 30 minutes.

[0102] The resulting reaction mixture was then filtered to remove the generated NEt3·HCl. The resulting filter cake was washed with 1000 mL of petroleum ether. Subsequently, the filtrate, weighing 6590 g, was distilled to recover the petroleum ether and obtain crude diethyl methylphosphonate.

[0103] Finally, 557.8 g of diethyl methylphosphonate was obtained by distillation. The purity was 98.5% as determined by gas chromatography (GC), yielding a yield of 96.1%.

[0104] Step 2: Preparation of ethyl(methyl)phosphonate (FR-1)

[0105] In a 1L three-necked flask equipped with a thermometer and a condenser, 557.0 g of a mixture of diethyl methylphosphonate and 27.50 g of p-toluenesulfonate was added. The flask was then purged with N2. The temperature was gradually increased, and the reaction mixture was vigorously stirred and refluxed. The oil temperature was slowly increased from 120°C to 170°C before insulation. After 9 hours, no significant reflux was observed (the raw material was less than 0.5% as detected by GC), indicating that the reaction was complete.

[0106] Finally, 535.0 g of FR-1 with a viscosity of 3.5 mPa·s was obtained by vacuum distillation (2 to 3 kPa, 101°C). The purity of the product determined by GC was 98%, and a yield of 98% was obtained.

[0107]

[0108] 2.2 Synthesis Example 2: Preparation of FR-2

[0109] Methyldichlorophosphine was continuously fed into the vaporizer at a flow rate of 119.39 g / h. Then, using a nitrogen stream, the vaporized methyldichlorophosphine was transferred to a tower-type continuous reactor at a rate of 80 mL / min.

[0110] Meanwhile,99.5% n-Butanol was introduced into another vaporizer at a rate of 243 g / h. The vaporized butanol was also purged into a column reactor using a nitrogen stream at a rate of 80 mL / min. Subsequently, the vaporized methyl dichlorophosphine and n-butanol were rapidly reacted in the column reactor.

[0111] The resulting light fraction of chlorobutane produced by the rapid reaction was condensed and collected in a low-boiling-point receiving flask. The heavy fraction of crude methyl phosphine butyl ester produced during the reaction process was collected in a separate receiving flask and subsequently neutralized with triethylamine.

[0112] After neutralization, n-butanol was removed by vacuum distillation. This method yielded 96.0% methyl phosphine butyl ester with a viscosity of 3.4 mPa·s and a purity of 98.5% obtained by distillation.

[0113] 2.3 Synthesis Example 3: Preparation of FR-3

[0114] Step 1: Preparation of dibutyl methylphosphonite

[0115] In a 25 L autoclave equipped with a thermometer and a condenser, a mixture of 6200 g of petroleum ether, 674 g of anhydrous n-butanol and 910 g of triethylamine was added. The reaction system was purged three times with nitrogen, and then a solution of 507 g of methyldichlorophosphine was added dropwise at -10 °C. Once the addition was complete, the temperature was maintained at 0 °C for 30 minutes.

[0116] The resulting reaction mixture was then pressure filtered to remove the generated NEt3·HCl. The resulting filter cake was washed with 1000 mL of petroleum ether. Subsequently, the filtrate of 7506 g was distilled to recover the petroleum ether and obtain crude dibutyl methylphosphonite.

[0117] Finally, 756.7 g of dibutyl methylphosphonite was obtained by distillation. The purity, as determined by gas chromatography (GC), was 95%, yielding an 88% yield.

[0118] Step 2: Preparation of Butyl(methyl)phosphonate (FR-3)

[0119] In a 1L three-necked flask equipped with a thermometer and a condenser, 600 g of a mixture of dibutyl methylphosphonate and 30 g of p-toluenesulfonate was added. The flask was then purged with N2. The temperature was gradually increased while the reaction mixture was vigorously stirred and gently refluxed. The oil temperature was slowly increased from 150°C to 180°C before insulation. After 6 hours, the raw material concentration detected by GC was less than 0.5%, indicating the completion of the reaction.

[0120] Finally, 571 g of FR-3 product with a viscosity of 6.4 mPa·s was obtained by vacuum distillation (0.2~0.3 kPa, 86°C). The purity of the product, as determined by GC, was 98%, yielding a 98.0% yield.

[0121] 3. Hydrolytic Stability Comparison Test

[0122] The hydrolytic stability provided by different flame retardants was compared by measuring the acid value of polyol blends containing flame retardants and water over time during storage at elevated temperatures. For this purpose,90 g of polyol, 9 g of flame retardant, and 4.5 g of water were homogenized by stirring at 1500 rpm for 2 minutes. The acid value was then determined using a 3:1 (v / v) isopropanol / water mixture as the solvent and 0.1 N NaOH (water) solution as the titrant. The samples were then stored at 40 °C, and the acid values ​​were determined after 11, 17, and 28 days. The samples were homogenized by stirring at 1500 rpm for 2 minutes prior to analysis. The acid value development of the polyol-water blend without added flame retardant was also determined after 11 and 28 days, as shown in Table 1.

[0123] Table 1 Comparison of hydrolytic stability: Acid value assessment of polyol blends containing flame retardant and water over time during storage at 40°C. (Page 8 / 12, CN 121219302 A)

[0124] Compared to a reference without flame retardant, Example FR-1 of the present invention did not cause a significant increase in the acid value of its polyol blends during and after storage at 40°C for the entire 28-day period. This indicates the high hydrolytic stability of FR-1 during storage in the polyol blends, i.e., the hydrolysis of FR-1 is zero to negligible. In contrast, under the same storage conditions, the acid value of the polyol blends containing Ref-2 increased significantly after only 11 days, which can only be explained by the hydrolysis of Ref-2.

[0125]

[0126] 4. Comparison of viscosity of polyol-flame retardant mixtures

[0127] As mentioned above, the viscosity of the liquid flame retardant of the present invention is advantageously low, which facilitates easy processing and handling in industrial applications. In the provided synthetic examples, measured by DIN 51398, FR-1 and FR-2 both have a viscosity of less than 5 mPa·s at room temperature, FR-3 has a viscosity of less than 7 mPa·s, while TCPP (Ref-1) typically has a viscosity ten times higher (60-70 mPa·s).

[0128] Table 2 below compares the viscosities of pure polyol (P2) and mixtures of polyol (P2) with flame retardants (FR-1, FR-2, FR-3, or Ref-1). The polyol-flame retardant mixture was prepared by combining polyol P2 with a specific flame retardant (FR-1, FR-2, FR-3, or Ref-1) at a weight ratio of 89.5:10.5 at room temperature. The mixture was thoroughly mixed at 1000 rpm for 1 minute using a mechanical stirrer to ensure homogeneity. The dynamic viscosity of the pure polyol and the polyol-flame retardant mixture was then measured according to DIN 51398.

[0129] Table 2: Viscosity of pure polyols and polyol-flame retardant mixtures at room temperature

[0130] As can be seen from the data in Table 2, the liquid flame retardant of the present invention is superior to conventional liquid flame retardants in effectively reducing the viscosity of polyol-flame retardant mixtures during the blending process.Additional advantages of TCPP (Ref-1). This advantageous property can further enhance overall processability when used in polymer manufacturing.

[0131] 5. Formulation and performance testing of flexible polyurethane (PUR) foam

[0132] The stannous catalyst, polyol, flame retardant, water, foam stabilizer and amine catalyst were weighed into a dry beaker in this order and premixed for 60 seconds at 500 rpm (for polyether polyol formulations) or 1000 rpm (for polyester polyol formulations). After adding TDI, the mixture was stirred at 2500 rpm for 7 seconds. The resulting material was quickly poured into a paper liner box mold (page 9 / 12, CN 121219302 A, 25*26*26 cm). The rise time and further observations were recorded during the foaming process. The foam was cured at room temperature for about 16 hours, and then cut and collected from each comparative example (C1-C3) or example of the present invention (I1-I2) for further evaluation.

[0133] In each case, the selection of polymerization catalyst, foam stabilizer, and TDI for each foam embodiment was guided by existing experience on optimal foamability, details of which are listed in Table 3 below.

[0134]

[0135] Table 3: Polyols, Flame Retardants, Catalysts, Foam Stabilizers & TDI for Each PUR Foam Embodiment

[0136] Evaluation of Flame Retardancy of Flexible Foam (FMVSS 302)

[0137] As described in Federal Motor Vehicle Safety Standard 302 (FMVSS 302), the efficiency of the flame retardant was evaluated by testing the combustion behavior of a flexible polyurethane foam sample containing the flame retardant at a target density of 30 kg / m3 in a horizontal burning test. The foam density in the embodiment was measured according to DIN 53420. According to this standard, if the flame did not travel beyond the 38 mm mark on the specimen but extinguished within that distance, the sample was assigned the highest rating (SE, "self-extinguishing"). Lower grades include SE / NBR (Self-extinguishing / Non-burning rate), SE / B (Self-extinguishing / burning rate), and B (burning rate). Five sample specimens were cut from each foam and this test was performed. The lowest-rated specimen determined the overall grade of the foam.

[0138] The flame retardancy of the tested flexible foam examples is compared in Table 4.

[0139] Table 4: Performance data of flexible polyurethane polyether (P1) foam formulations

[0140] *The amounts of all components are given in parts per 100 parts by weight of polyol (php).

[0141] As indicated by the performance data listed in Table 4,Comparative Example C1 (polyether polyurethane foam without flame retardant additives, page 10 / 12, CN 121219302 A) did not meet the required flame retardancy standard. Using 12 php of the halogenated reference flame retardant TCPP (Ref-1), Comparative Example C2 provided a polyether polyurethane foam that met the required flame retardancy. When attempting to reduce the amount of flame retardant to 8 php TCPP, as shown in Comparative Example C3, it was found that the amount of flame retardant was insufficient, and the resulting foam did not achieve optimal flame retardancy (SE).

[0142] Example I1 of the present invention demonstrates the effectiveness of the halogen-free flame retardant (FR-1) of the present invention in achieving the optimal flame retardancy standard for polyether polyurethane foam, even at a low loading of only 4 php.

[0143] Example I2 of the present invention, a polyether polyurethane foam having 4 php of the halogen-free flame retardant (FR-2) of the present invention, exhibited the same excellent flame retardancy rating as I1.

[0144] 6. Formulation and Performance Testing of Rigid Polyisocyanurate (PIR) Foam

[0145] Octyl ester catalyst, polyol, flame retardant, water, foam stabilizer and amine catalyst were weighed into a dry beaker in this order and premixed at 1000 rpm for 50 seconds. After adding n-pentane, the mixture was stirred at 1000 rpm for 10 seconds to incorporate it into the mixture. MDI was then added to the mixture and the liquid was mixed at 2500 rpm for 7 seconds. The resulting material was quickly poured into a paper liner mold (25*26*26 cm). The rise time and further observations were recorded during the foaming process. The foam was cured at room temperature for approximately 16 hours, and then cut and collected from each comparative example (C4-C6) or example of the present invention (I3-I4) for further evaluation.

[0146] The selection of polymerization catalyst, foam stabilizer and MDI for each rigid foam example was guided by existing experience on optimal foamability in each case, details of which are listed in Table 5 below.

[0147] Table 5: Polyols, Flame Retardants, Catalysts, Foam Stabilizers and MDI Used in PIR Foam Examples

[0148] Flame Retardancy Assessment Method for Rigid Foams (DIN4102-1)

[0149] DIN4102-1 classifies building materials according to their flammability. This effective standard distinguishes between two fire ratings. “A” represents non-flammable material and “B” represents flammable material. Rating B is associated with polyurethane foams, such as PIR-insulation boards. It is then subdivided into the following levels: B1 = low flammability; B2 = normal flammability; B3 = high flammability. For reference, most building foam systems in spray cans sold in Germany correspond to building material rating B2. The main grading criterion for flammability rating B2 is the flame height in a vertical burning test, which needs to be kept below a maximum value of 150 mm.This is an ideal criterion for benchmark testing of the flame retardancy of building materials.

[0150] The flame retardancy of different rigid PIR foam samples was evaluated using DIN4102-1, as listed in Table 6 below.

[0151] Table 6: Performance data of rigid polyisocyanurate polyester (P2) foam formulation, 11 / 12 pages, 14 CN 121219302 A

[0152] *The amounts of all components are given in parts per 100 parts by weight of polyol (php).

[0153] As the performance data listed in Table 6 indicate, Comparative Example C4 (PIR foam without flame retardant additives) failed to meet the required flame retardancy standard rating of B2. By introducing 15 php of the halogenated reference flame retardant TCPP (Ref-1), Comparative Example C5 represents a rigid PIR foam with the required flame retardancy rating. However, when attempts were made to reduce the amount of this halogenated flame retardant to 12 php TCPP, as demonstrated in Comparative Example C6, it was observed that this reduced flame retardant content was insufficient, resulting in the foam failing to achieve the desired flame retardancy rating.

[0154] Example I3 of the present invention demonstrates the excellent flame retardancy achieved by introducing the same amount of 12 php of the halogen-free flame retardant FR-1 of the present invention into rigid PIR foam, meeting the optimal flame retardancy criteria.

[0155] Similarly, Examples I4 and I5 of the present invention achieve the same excellent flame retardancy rating by replacing FR-1 with the same amount of FR-2 or FR-3 as in I3, respectively. This further highlights the effectiveness of the halogen-free flame retardant of the present invention in achieving the desired level of flame retardancy in rigid foam. Specification 12 / 12 pages 15 CN 121219302 A,

Claims

1. A flame-retardant polyurethane obtained by reacting a polyol and an isocyanate in the presence of a flame retardant comprising a phosphonate of formula (I): wherein R1is a hydrocarbon radical selected from the group consisting of C1-C 12 alkyl and C6-C 20 aryl hydrocarbyl groups; and wherein R2and R3, the same or different, independently represent H or C1-C 12 alkyl.

2. The flame-retardant polyurethane according to claim 1, wherein R1 is selected from C1-C6 alkyl, preferably from C2-C4 alkyl.

3. The flame-retardant polyurethane according to claim 1 or 2, wherein R2 and R3 are not simultaneously H.

4. The flame-retardant polyurethane according to claim 3, wherein one of R2 and R3 is H or ethyl and the other is C1-C6 alkyl.

5. The flame-retardant polyurethane according to claim 3, wherein one of R2 and R3 is methyl and the other is H or C1-C4 alkyl.

6. The flame-retardant polyurethane according to claim 1, wherein R1 is ethyl, one of R2 and R3 is methyl and the other is ethyl.

7. The flame-retardant polyurethane according to claim 1, wherein R1 is butyl, one of R2 and R3 is methyl and the other is H.

8. The flame-retardant polyurethane according to claim 1, wherein R1 is butyl, one of R2 and R3 is methyl and the other is butyl.

9. A flame-retardant polyurethane foam obtained by reacting a polyol and an isocyanate in the presence of a flame retardant as defined in any one of claims 1-8, further in the presence of a blowing agent, a blowing catalyst and a foam stabilizer.

10. The flame-retardant polyurethane foam according to claim 9, wherein the polyurethane foam is a flexible foam.

11. The flame-retardant polyurethane foam according to claim 9, wherein the polyurethane foam is a rigid foam.

12. Use of the flame-retardant polyurethane according to any one of claims 1-8 or the flame-retardant polyurethane foam according to any one of claims 9-11 for the manufacture of door linings, headliner linings, seat covers, high resilience foam seats, high resilience foam mattresses, rigid foam insulation panels, visco-elastic foam mattresses, potting foams for battery applications, microcellular foam seals or gaskets, durable elastomeric vehicle wheels or tires, automotive suspension bushings, electrical potting compounds, high performance adhesives, surface coatings or sealants, synthetic fibers, carpet underlays or rigid or flexible plastic parts or hoses.

13. A method of manufacturing the flame-retardant polyurethane according to any one of claims 1-8, comprising: preparing a mixture comprising a polyol and the flame retardant; and adding an isocyanate compound to the mixture.

14. Use of a phosphinic acid ester of formula (I) as flame retardant for polyurethanes wherein R1is a hydrocarbon radical selected from the group consisting of C1-C 12 alkyl and C6-C 20 aryl hydrocarbyl groups; and wherein R2and R3, the same or different, independently represent H or C1-C 12 alkyl.

15. A flame-retardant polyurethane composition comprising a phosphinate ester of formula (I) as a flame retardant ###0002### (I) wherein R1is a hydrocarbon radical selected from the group consisting of C1-C 12 alkyl and C6-C 20 aryl hydrocarbyl; and wherein R2and R3, the same or different, independently represent H or C1-C 12 alkyl.