Phosphoric esters having very low triphenyl phosphate content

Abstract

The compositions include phosphates, such as alkyl and aryl phosphates, which have very low or no triphenyl phosphate (TPP) content. Methods of synthesizing phosphates are also disclosed, which target a control of TPP to below 0.1%, substantially reducing the potential toxicity of the products including the phosphates.

Description

Cross-reference to related applications

[0001] This application claims priority to U.S. Provisional Application No. 63 / 620943, filed January 15, 2024, which is incorporated herein by reference. Background Technology

[0002] Phosphate esters are widely used due to their flame-retardant properties, primarily as additives in wire and cable formulations. Phosphate esters can be non-halogenated, and these types are gradually replacing brominated flame retardants.

[0003] Triphenyl phosphate (CAS No. 115-86-6) is a well-known phosphate flame retardant, but it faces increasingly stringent regulations. European regulators added a risk assessment in 2017. In May 2023, France published its conclusions, stating that triphenyl phosphate (TPP) should be classified as an endocrine disruptor in Group 1 and recommending its addition to the SVHC (Substances of Very High Concern) list. This was a first step towards restricting the commercial use of this substance. In early November 2024, European authorities officially added TPP to the SVHC list.

[0004] Even if unintentionally added, TPP is a byproduct of the synthesis of other phosphate esters. It is difficult or impossible to remove it using techniques employed after synthesis. Summary of the Invention

[0005] The following is a brief overview of the topics covered in more detail herein. This overview is not intended to limit the scope of the claims.

[0006] This document discloses a composition comprising phosphate esters, such as alkyl phosphate esters and aryl phosphate esters, with very low or no TPP content. A method for synthesizing the phosphate esters is also disclosed, aiming to control the TPP content to below 0.1%, significantly reducing the potential toxicity of these products.

[0007] In some aspects, the techniques described herein relate to a composition comprising: phosphate ester compounds of formulas 1, 2, and 3. (1) (2) (3) R1 and R2 are independently selected from C4-C18 branched or straight-chain alkyl, C4-C18 branched or straight-chain alkenyl, C4-C18 branched or straight-chain alkoxy, C4-C18 branched or straight-chain hydroxyalkyl, branched or straight-chain C4-C18 alkyl ether, or mixtures thereof; wherein the weight of Formula 1 accounts for 75% or more of the total weight of all phosphate esters in the composition; and the weight of Formula 3 is less than 0.1% of the total weight of all phosphate esters in the composition; or the composition comprises phosphate ester compounds of Formula 4, Formula 5 and Formula 3; (4) (5) R3 and R4 are independently selected from C1-C10 branched or straight-chain alkyl, C1-C10 branched or straight-chain alkenyl, C1-C10 branched or straight-chain alkoxy, C1-C10 branched or straight-chain hydroxyalkyl, branched or straight-chain C1-C10 alkyl ether, or mixtures thereof, and the weight of Formula 3 is less than 0.1% of the total weight of all phosphate esters in the composition.

[0008] In some aspects, the technology described herein relates to a composition wherein R1 and R2 are independently selected from branched or straight-chain C4-C18 alkyl or branched or straight-chain C4-C18 alkyl ether groups; or wherein R4 and R5 are independently selected from branched or straight-chain C4-C18 alkyl or branched or straight-chain C4-C18 alkyl ether groups.

[0009] In some respects, the technology described herein relates to a composition wherein R1 and R2 are 2-ethylhexyl.

[0010] In some respects, the technology described herein relates to a composition wherein R1 and R2 are straight-chain or branched C10 alkyl groups.

[0011] In some respects, the technology described herein relates to a composition wherein R1 and R2 are independently selected from linear or branched C-chain compounds. 10 H 21 -C 12 H 25 -C 14 H 29 or -C 16 H 33 Group.

[0012] In some respects, the technology described herein relates to a composition in which the structure of Formula 2 is present at 20% to 1% by weight of all phosphate esters in the composition.

[0013] In some respects, the techniques described herein relate to a composition in which the structure of Formula 3 is present at 0.01% to 0.05% by weight of the total compound.

[0014] In some respects, the technology described herein relates to a composition wherein R3 and / or R4 are tert-butyl.

[0015] In some aspects, the technology described herein relates to a polymer composition comprising: (a) a polymer selected from polyvinyl chloride (PVC), polyurethane, polyvinyl acetate, polyvinyl butyral, polystyrene, nitrocellulose, nitrile rubber, ABS, polycarbonate, polyamide, polyester, epoxy resin, and combinations thereof; and (b) a phosphate ester composition comprising phosphate ester compounds of formulas 1, 2, and 3 as listed above, wherein R1 and R2 are independently selected from C4-C18 branched or straight-chain alkyl groups, C The phosphate ester composition comprises 4-C18 branched or straight-chain alkenyl, C4-C18 branched or straight-chain alkoxy, C4-C18 branched or straight-chain hydroxyalkyl, branched or straight-chain C4-C18 alkyl ether, or a mixture thereof; wherein the weight of Formula 1 accounts for 75% of the total weight of all phosphate esters in the composition; and the weight of Formula 3 is less than 0.1% of the total weight of all phosphate esters in the composition; or the phosphate ester composition comprises or is as described above a phosphate ester compound of Formula 4, Formula 5 and Formula 3, wherein the weight of Formula 3 is less than 0.1% of the total weight of all phosphate esters in the composition.

[0016] In some respects, the technology described herein relates to a composition in which the polymer is selected from PVC and polyurethane.

[0017] In some aspects, the technology described herein relates to a composition wherein R1 and R2 are independently selected from branched or straight-chain C4-C18 alkyl or branched or straight-chain C4-C18 alkyl ether groups; or wherein R4 and R5 are independently selected from branched or straight-chain C1-C10 alkyl or branched or straight-chain C1-C10 alkyl ether groups.

[0018] In some respects, the technology described herein relates to a composition wherein R1 and R2 are independently selected from 2-ethylhexyl, straight-chain or branched-C 10 H 21 -C 12 H 25 -C 14 H 29 or -C 16 H 33 Group; or R3 and / or R4 are tert-butyl groups.

[0019] In some aspects, the technology described herein relates to a method for preparing a phosphate ester having a low triphenyl phosphate content, the method comprising: reacting an alcohol of formula R0OH with POCl3 to produce a reaction mixture containing an intermediate; wherein the molar ratio of the alcohol of formula R0OH to POCl3 is provided in a ratio of ≥1.10 to 1; wherein R0 is an alkyl group selected from the group consisting of C4-C18 branched or straight-chain alkyl, C4-C18 branched or straight-chain alkenyl, C4-C18 branched or straight-chain alkoxy, C4-C18 branched or straight-chain hydroxyalkyl, branched or straight-chain C4-C18 alkyl ether, or a mixture thereof; reacting the intermediate with an intermediate... The phenol is reacted with a phenolic compound to form a composition comprising a phosphate monoester, the phosphate monoester comprising an alkyl group corresponding to R0; or a substituted phenol is reacted with POCl3, wherein the phenol is substituted by a substituent group R3 and / or R4; wherein the substituted phenol is provided at a molar ratio of the substituted phenol to POCl3 ≥ 1.65:1; wherein R3 and R4 are independently selected from C1-C10 branched or straight-chain alkyl, C1-C10 branched or straight-chain alkenyl, C1-C10 branched or straight-chain alkoxy, C1-C10 branched or straight-chain hydroxyalkyl, branched or straight-chain C1-C10 alkyl ether, or mixtures thereof.

[0020] In some aspects, the technology described herein relates to a method for preparing a phosphate ester with low triphenyl phosphate content, the method comprising: reacting an alcohol of formula R0OH with POCl3 to produce a reaction mixture containing an intermediate; wherein the alcohol having formula R0OH is provided in a POCl3 molar ratio of ≥1.10 to 1; wherein R0 is an alkyl group selected from: C4-C18 branched or straight-chain alkyl, C4-C18 branched or straight-chain alkenyl, C4-C18 branched or straight-chain alkoxy, C4-C18 branched or straight-chain hydroxyalkyl, branched or straight-chain C4-C18 alkyl ether, or a mixture thereof; reacting the intermediate... Reaction with a phenolic compound to form a composition comprising a phosphate monoester, said phosphate monoester comprising an alkyl group corresponding to R0; or reaction of a substituted phenol with POCl3, wherein the phenol is substituted by a substituent group R3 and / or R4; wherein said substituted phenol is provided at a molar ratio of said substituted phenol to POCl3 ≥ 1.65:1; wherein R3 and R4 are independently selected from C1-C10 branched or straight-chain alkyl, C1-C10 branched or straight-chain alkenyl, C1-C10 branched or straight-chain alkoxy, C1-C10 branched or straight-chain hydroxyalkyl, branched or straight-chain C1-C10 alkyl ether, or mixtures thereof.

[0021] In some respects, the techniques described herein relate to a method in which the composition comprises less than 0.1% by weight of triphenyl phosphate of the total weight of the phosphate ester.

[0022] In some respects, the techniques described herein relate to a method in which, after the step of reacting an alcohol of the formula R0OH with POCl3, the reaction is maintained for more than 15 minutes after all the alcohol and POCl3 have been added, and then the step of reacting the intermediate with the phenolic compound is continued.

[0023] In some respects, the techniques described herein relate to a method in which, after the step of reacting an alcohol of the formula R0OH with POCl3, the reaction is maintained at a temperature of 1°C to 20°C.

[0024] In some respects, the techniques described herein relate to a method in which the temperature is maintained between 1 and 20 °C during the step of reacting an alcohol of the formula R0OH with POCl3.

[0025] In some respects, the techniques described herein relate to a method in which the step of reacting an alcohol of formula R0OH with POCl3 is carried out under partial vacuum, or under partial vacuum after the addition of a substituted phenol.

[0026] In some aspects, the technology described herein relates to a method in which the phosphate ester composition comprises phosphate ester compounds of formula 1, 2, and 3, wherein R1 and R2 are independently selected from C4-C18 branched or straight-chain alkyl, C4-C18 branched or straight-chain alkenyl, C4-C118 branched or straight-chain alkoxy, C4-C18 branched or straight-chain hydroxyalkyl, branched or straight-chain C4-C18 alkyl ether, or mixtures thereof; wherein the weight of formula 1 accounts for 75% of the total weight of the phosphate ester compounds in the composition; and the weight of formula 3 is less than 0.1% of the total weight of the phosphate ester compounds in the composition; or the phosphate ester composition comprises the phosphate ester compounds of formula 4, 5, and 3, wherein the weight of formula 3 is less than 0.1% of the total weight of the phosphate ester compounds in the composition.

[0027] In some respects, the techniques described herein relate to a method in which a substituted phenol reacts with POCl3 in a molar ratio of substituted phenol to POCl3 of 1.75:1 to 2.5:1; the order of addition is that the substituted phenol is added to POCl3.

[0028] The foregoing summary provides a simplified overview to offer a basic understanding of some aspects of the systems and / or methods discussed herein. This summary is not a comprehensive overview of the systems and / or methods discussed herein. It is not intended to identify key / important elements or describe the scope of such systems and / or methods. Its sole purpose is to present some concepts in a simplified form as a prelude to a more detailed description later. Detailed Implementation

[0029] Various techniques relating to triphenyl phosphate containing very low levels of triphenyl phosphate (TPP) are now described. In the following description, numerous specific details are set forth for illustrative purposes in order to provide a thorough understanding of one or more aspects. However, it will be apparent that these aspects can be practiced without these specific details.

[0030] As used herein, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless otherwise stated or the context clearly indicates otherwise, the phrase “X uses A or B” is intended to mean any natural inclusive arrangement. Specifically, the phrase “X uses A or B” satisfies any of the following: X uses A; X uses B; or X uses both A and B. Furthermore, “a” and “an” as used in this application and the appended claims should generally be interpreted as “one or more” unless otherwise stated or clearly indicated from the context as a singular form.

[0031] If a molecular weight is provided, such as the molecular weight of a polymer, the molecular weight should be understood as the average molecular weight, unless otherwise stated or understood from the context.

[0032] Triphenyl phosphate (TPP) is a byproduct of most commercial alkylaryl phosphates and triaryl phosphates. This paper describes the testing of several commercial products using gas chromatography to determine the TPP percentage content. The TPP content in commercially available products ranges from 40% to 1%. Given that the TPP percentage already meets the criteria for inclusion in the SVHC list, it was determined that a reduction in the TPP percentage in alkylaryl phosphates and triaryl phosphates is necessary.

[0033] The phosphate ester compositions disclosed herein may include various alkylaryl phosphate esters. In one embodiment, the phosphate ester includes one or more compounds of structures 1 and 2. Structure 1 Structure 2 Structure 3 (TPP)

[0034] In structures 1 and 2, R1 and R2 are independently selected from C4-C18 branched or straight-chain alkyl, C4-C18 branched or straight-chain alkenyl, C4-C18 branched or straight-chain alkoxy, C4-C18 branched or straight-chain hydroxyalkyl, branched or straight-chain C4-C18 alkyl ether, or mixtures thereof. The C4-C18 alkyl, C4-C18 alkenyl, C4-C18 alkoxy, and C4-C18 hydroxyalkyl can be selected from, for example, C5-C16, C6-C14, or C8-C12.

[0035] In certain embodiments, R1 and R2 are independently selected from C4-C18 alkyl or C4-C18 alkyl ether groups. In other embodiments, R1 and R2 are independently selected from straight-chain or branched C8 groups, such as 2-ethylhexyl, or C10 groups, such as isodecanol. In other embodiments, R1 and R2 are independently selected from straight-chain or branched C12, C14, or C16 groups, or R1 and R2 are independently selected from 2-ethylhexyl, straight-chain or branched -C 10 H 21 -C 12 H 25 -C 14 H 29 or -C 16 H 33 Group; or R3 and / or R4 are tert-butyl groups.

[0036] Specific examples of phosphate esters corresponding to structure 1 are 2-ethylhexyl diphenyl phosphate (CAS No. 1241-94-7), isodecyl diphenyl phosphate (CAS No. 29761-21-5), and C. 12 -C 16 Alkyl diphenyl phosphate.

[0037] In one embodiment, the phosphate ester is non-halogenated, such as non-brominated and non-chlorinated. In one embodiment, the molecular weight of the phosphate ester is from 650 g / mol to 325 g / mol, for example from 520 g / mol to 350 g / mol, or from 480 g / mol to 390 g / mol.

[0038] In one embodiment, the weight content of structure 1 in the phosphate ester composition is ≥75% of the total weight of formulas 1, 2, and 3 (or the total weight of the composition), for example, structure 1 accounts for 76% to 99.9%, 80% to 95%, or 85% to 90%. Structure 2 may be present at a weight of 24.999% to 0.0001% of the total weight of formulas 1, 2, and 3 (or the total weight of the composition), for example, 20% to 1%, or 15% to 5%.

[0039] In one embodiment, the phosphate ester comprises one or more substituted triphenyl phosphate compounds with structures 4 and 5, wherein one or both phenyl groups are substituted with substituents R3, R4. Structure 4 Structure 5

[0040] In structures 4 and 5, substituents R3 and R4 are independently selected from C1-C10 branched or straight-chain alkyl, C1-C10 branched or straight-chain alkenyl, C1-C10 branched or straight-chain alkoxy, C1-C10 branched or straight-chain hydroxyalkyl, branched or straight-chain C1-C10 alkyl ether, or mixtures thereof. The number of carbon atoms in the C1-C10 alkyl, C1-C10 alkenyl, C1-C10 alkoxy, and / or C1-C10 hydroxyalkyl can be selected, for example, from C2 to C9, C3 to C7, or C4 to C6. In a particular embodiment, R3 and / or R4 is tert-butyl.

[0041] In one embodiment, the substituted triphosphate compound is non-halogenated, non-brominated, or non-chlorinated. In one embodiment, the molecular weight of the phosphate ester is from 700 g / mol to 375 g / mol, for example from 620 g / mol to 400 g / mol, or from 450 g / mol to 420 g / mol.

[0042] In one embodiment, the weight content of structure 4 in the substituted triphenyl phosphate composition is ≥40% of the total weight of formulas 4, 5 and 3, i.e., the total weight of all phosphate esters (or the total weight of the composition), for example, structure 4 accounts for 55% to 85%, 60% to 80% or 65% to 75% by weight. Structure 5 may be present in an amount of 60% to 0.0001%, for example, 50% to 1% or 40% to 5%.

[0043] In compositions containing structures 1 and 2 or structures 4 and 5, the phosphate ester composition conventionally has a content of structure 3 (TPP) of 0.5% to 3%. In contrast, the total TPP weight percentage of the phosphate ester compositions disclosed herein is less than 0.1% (as expressed as the weight of TPP / total weight of phosphate ester (such as each of formulas 1-5, or the total weight of the composition), such as 0.0001% to 0.09%, 0.001% to 0.08%, 0.01% to 0.05%, or 0.015% to 0.045%).

[0044] The phosphate ester composition may also contain very small amounts of phenol and water, for example, 1 to 500 ppm, such as 10 to 300 ppm respectively.

[0045] Some consumer and industrial products may include phosphate ester compositions as components. For example, flame-retardant materials use phosphate esters as flame retardants, and polymer materials can use phosphate esters as plasticizers. In some applications, phosphate esters function as both plasticizers and flame retardants.

[0046] In particular, non-halogenated phosphate esters are highly valuable in flame-retardant materials. The working principle of phosphate esters is to create a covering or extinguishing effect within the solid phase of the burning material. When exposed to the heat generated by a fire, the phosphate ester reacts to form a polymeric form of phosphorous acid. The thermally activated polymeric phosphorous acid creates a char layer on the burning material, preventing it from contacting oxygen. This slows down or stops the combustion reaction.

[0047] Phosphate esters can be used in polymer compositions such as polyvinyl chloride (PVC), polyurethane, polyvinyl acetate, polyvinyl butyral, polystyrene, nitrocellulose, nitrile rubber, ABS, polycarbonate, polyamide, polyester, epoxy resin, and combinations thereof. Phosphate esters provide plasticizing effects and can also be used to improve the fire resistance and / or smoke suppression of materials. Plasticizers can be used to improve the processing characteristics and final properties of materials. Materials such as wires, cables, flooring, textiles (polymer-coated fabrics), belts, hoses, structural foams, paints, coatings, oils, and lubricants may benefit from the phosphate ester compositions disclosed herein.

[0048] In one embodiment, the phosphate ester composition comprises a material in which the total weight percentage of TPP is less than 0.1% (TPP weight / total phosphate ester weight), for example, 0.0001% to 0.09%, 0.001% to 0.08%, or 0.01% to 0.05% (TPP weight / total phosphate ester weight). Furthermore, the polymer material contains a polymeric material with a total weight percentage of TPP of less than 0.1% (TPP weight / total material weight), for example, 0.0001% to 0.09%, 0.001% to 0.08%, or 0.01% to 0.05% (TPP weight / total material weight).

[0049] In one embodiment, 2-ethylhexyl diphenyl phosphate is synthesized via a three-step reaction. The first step begins with POCl3 and 2-ethylhexanol as starting materials. These fluids are mixed together, providing more than 10% or more of 2-ethylhexanol. The stoichiometric ratio of 2-ethylhexanol to POCl3 is ≥1.10, for example, 1.10 to 2, or 1.11 to 1.5, or 1.2 to 1.3. In one embodiment, the reaction is cooled to below room temperature, for example, 1 to 22°C, such as 5 to 15°C, or 8 to 12°C. Cooling and / or metering of reactants can be performed during the reaction to maintain a low reaction temperature, for example, 1 to 20°C, such as 8 to 18°C, or 12 to 16°C. A partial vacuum, for example, a pressure of 10 to 75 mmHg, such as 20 to 60 mmHg or 30 to 50 mmHg, can also be applied to the reaction flask as the reaction proceeds.

[0050] In existing methods for preparing this compound, the ratio is equal or slightly excess, for example, 1.0–1.05. Surprisingly, small variations in these component ratios resulted in unexpected improvements in reducing TPP byproducts to below 0.1 wt.%.

[0051] Another unexpected process improvement was extending the holding time at the end of step 1 to ≥15 minutes. This contrasts sharply with previous practices, which lasted only 0-5 minutes. Holding time refers to the time after all reactants have been added. Holding may also include mixing or stirring. By extending this step, a reduction in TPP content was observed. After mixing the two components, the reaction can be held for ≥15 minutes, such as 15.5 to 60 minutes, 16 to 25 minutes, or 17.5 to 22.5 minutes. During the holding time of the reaction mixture, its temperature can be controlled, for example, at 1 to 20°C, such as 5 to 15°C or 8 to 12°C. Extending the holding time allows as many POCl3 molecules as possible to react with the alcohol. This reaction is advantageous at lower temperatures, such as 8 to 18°C ​​or 12 to 16°C. Once the POCl3 is reduced to a very small amount, the TPP% can be controlled below 0.1%. This is because the POCl3 entering step 3 is considered to be the chemical substance that reacts to generate TPP.

[0052] In some embodiments, the reaction mixture may be maintained for a further period of time, such as 15.5 to 60 minutes, 16 to 25 minutes, or 17.5 to 22.5 minutes, and / or may be further maintained under partial vacuum and heated to, for example, 28 to 45°C, such as 30 to 40°C or 33 to 38°C. This step is to further complete the reaction between all the starting materials. At this stage, the monoester between POCl3 and the alcohol is the dominant species. Due to the excess of alcohol, there is a small amount of diester. This part is at a relatively high temperature to use up all the starting materials before proceeding to step 3.

[0053] Step 1 is as shown in reaction scheme (Ia). (Ia)

[0054] In step 1, a sufficient excess of alcohol should be provided, the holding time at the end of step 1 should be long enough, and the temperature should be low enough to allow the POCl3 molecules to react with the alcohol and form a monoester. Without being bound by theory, it is believed that these reaction conditions help remove unreacted POCl3 molecules, preventing them from proceeding to step 3, where they might react with sodium phenolate. Any unreacted POCl3 molecules may react in step 3 to become TPP.

[0055] If the reaction is heated to a higher temperature too early at the end of step 1, the already formed monoesters (i.e., dichloroesters) can further react with the free alcohol and consume all of the free alcohol. This deprives the remaining POCl3 molecules of the opportunity to become monoesters and increases the chance of TPP formation in step 3.

[0056] Step 2 is described in reaction scheme (Ib). Sodium hydroxide (NaOH) is added to phenol. This produces an intermediate product, a sodium phenolate compound, and water. (Ib)

[0057] For example, the reaction can be cooled to below 50°C, such as from 45°C to 35°C, or from 42°C to 38°C.

[0058] Step 3 is as shown in reaction scheme (Ic). The intermediate sodium phenoxide compound from step 2 is combined with the intermediate product from step 1, namely 2-ethylhexyl dichlorophosphate (Ic). The molar ratio of sodium phenoxide to 2-ethylhexyl dichlorophosphate is 2:1. This produces the final product 2-ethylhexyl diphenyl phosphate and a sodium chloride salt. When carried out under the conditions described above regarding excess alcohol and / or a long holding time after step 1, very little TPP is generated in the final product through these steps 1-3 and reaction schemes (Ia, Ib, Ic). (Ic)

[0059] In one embodiment, water and alkali can be mixed and cooled to 20°C before the addition of phenol, thereby controlling the temperature of the reaction in step 3, for example, keeping it below 50°C, such as 45°C to 35°C, or 42°C to 38°C.

[0060] In one embodiment, at the end of the reaction in step 3, water may be added, followed by HCl to adjust the pH of the system to, for example, 9 to 12, such as 9.5 to 11.5, or 10 to 11.

[0061] In one embodiment, isodecanyl diphenyl phosphate is similarly prepared via a three-step reaction. The same temperature range for the reaction steps listed above for the 2-ethylhexyl diphenyl phosphate embodiment is applicable to the isodecanyl diphenyl phosphate embodiment.

[0062] The first step involves using POCl3 and isodecanol as starting materials. These fluids are mixed together to provide more than 10% isodecanol. The stoichiometric ratio of isodecanol to POCl3 is ≥1.10, for example, 1.10 to 2, or 1.11 to 1.5, or 1.2 to 1.3.

[0063] In previous methods for preparing this compound, the ratios were equal or slightly excess (1.0–1.05). Surprisingly, these small changes in component ratios yielded an unexpected improvement in reducing TPP byproducts to below 0.1% by weight. HCl was the major byproduct.

[0064] After mixing the two components, the reaction is maintained for ≥15 minutes, such as 15.5 to 60 minutes, 16 to 25 minutes, or 17.5 to 22.5 minutes. During the maintenance of the reaction mixture, its temperature can be controlled, for example, at 1 to 20°C, such as 5 to 18°C, or 12 to 15°C. This produces the first intermediate product. Step 1 is described in reaction scheme (IIa). (IIa)

[0065] Similar to reaction scheme Ia, this method was improved by extending the hold time at the end of step 1 to ≥15 minutes. Extending this step resulted in a further reduction in TPP content.

[0066] In step 1, a sufficient excess of alcohol should be provided, the holding time at the end of step 1 should be long enough, and the temperature should be low enough to allow POCl3 to react with the alcohol and form a monoester. Without being bound by theory, these reaction conditions are believed to help remove unreacted POCl3 molecules, preventing them from proceeding to step 3 (where they might react with sodium phenoxide). Any unreacted POCl3 molecules may react in step 3 to become TPP.

[0067] If the reaction is heated to a higher temperature too early at the end of step 1, the already formed monoesters (i.e., dichloroesters) can further react with the free alcohol and consume all of the free alcohol. As with the reactions described above, this is believed to deprive the remaining POCl3 molecules of the opportunity to become monoesters and increase the formation of TPP in step 3.

[0068] Step 2 is the same as in reaction scheme (IIb) described above, as in Ib. Sodium hydroxide (NaOH) is added to the phenol. This produces sodium phenolate compound and water. (IIb)

[0069] Step 3, as shown in reaction scheme (IIc), involves mixing the sodium phenolate compound from step 2 with the product of step 1, isodex dichlorophosphate, (IIc). This produces the isodex diphenyl phosphate final product and a sodium chloride salt. When carried out under the conditions described above regarding excess alcohol and / or prolonged maintenance after step 1, very little TPP is generated in the final product through these steps 1-3 and reaction schemes (IIa, IIb, IIc). (IIc)

[0070] The process steps for the specific phosphate ester final product described above can be applied to other embodiments, wherein in step 1, the alcohol is added at a molar ratio of 1.10 to 1 or other ratios described above. The alcohol (ROOH) may have an RO group selected from C4-C18 branched or straight-chain alkyl, C4-C18 branched or straight-chain alkenyl, C4-C18 branched or straight-chain alkoxy, C4-C18 branched or straight-chain hydroxyalkyl, branched or straight-chain C4-C18 alkyl ether, or mixtures thereof. The C4-C18 alkyl, C4-C18 alkenyl, C4-C18 alkoxy, and C4-C18 hydroxyalkyl groups may be selected from, for example, C5-C16, C6-C14, or C8 to C12.

[0071] To continue the synthesis, steps 2 and 3 are performed as described above, with the intermediate product from step 1 added to the phenol intermediate product from step 2 as described above in step 3. A base other than NaOH, such as KOH, can be used.

[0072] In each of the above synthesis steps, the reaction mixture after step 3 undergoes separation (removal of the oily product layer) and purification steps (e.g., washing) to obtain the phosphate ester composition.

[0073] In one embodiment, the substituted triphenyl phosphate is synthesized in a two-step single-vessel reaction as shown in reaction scheme (III). (III)

[0074] In the first step, the starting materials are POCl3, aluminum chloride (AlCl3), and p-tert-butylphenol (PTBP). POCl3 / AlCl3 is initially present in the reaction vessel, followed by the addition of additional PTBP, preferably heated to, for example, 50 to 95°C, such as 55 to 85°C or 65 to 75°C. Aluminum chloride acts as a catalyst and can be provided in small quantities, for example, at a molar ratio to POCl3 of 1:100 to 1:10, such as 1:80 to 1:20 or 1:40 to 1:60.

[0075] The POCl3 / AlCl3 mixture is then heated at a second temperature for a period of time, such as 30 minutes to 24 hours, 1 hour to 4 hours, or 1.5 hours to 3 hours. The second temperature can be 100 to 200°C, such as 110 to 150°C, or 115 to 135°C.

[0076] Following this further heating, phenol is added to the mixture at a second temperature, and this second temperature is maintained for a period of time, such as 1 to 5 hours, 2 to 4 hours, or 2.5 to 3.5 hours. After this period, a partial vacuum can be applied to the reaction flask during the second period, for example, at a pressure of 20 to 85 mmHg, 30 to 70 mmHg, or 40 to 60 mmHg. The second period can be, for example, 0.25 to 2 hours, 0.5 to 1.5 hours, or 0.4 to 0.75 hours. The second temperature can be maintained during the second period. After the second period, the reaction is cooled to a temperature below the second temperature, for example, 25 to 100°C, 40 to 90°C, or 50 to 85°C.

[0077] Then, in the second step, more reactants are added. First, a caustic alkali, such as NaOH or KOH, is added. This alkali can be diluted in water and functions to neutralize the aluminum chloride catalyst. Then, optionally, an organic acid, such as gluconic acid, can be added to adjust the pH to near neutral 7, for example, 6.8 to 7.2. The reaction can proceed for a third time, with the temperature controlled at elevated levels, such as 40°C to 95°C, 50°C to 90°C, or 60°C to 80°C. The third time period can be, for example, 0.5 to 24 hours, for example, 0.75 to 5 hours, or 1 to 3 hours.

[0078] Subsequently, the reaction mixture undergoes separation (removal of the oily product layer) and purification steps (e.g., washing) to obtain the substituted triphenyl phosphate composition. Commercially viable yields of 75% or higher, such as 80 to 98% or 85 to 95%, can be achieved.

[0079] The stoichiometric ratio of p-tert-butylphenol to POCl3 used in this process is ≥1.65:1, for example, 1.75:1 to 2.5:1, 1.85:1 to 2.1:1, or 1.9:1 to 2.0:1. As shown in the examples, this molar ratio, as well as the order of addition of alkyl-substituted phenol and POCl3, affects the final product to control TPP.

[0080] It should be understood that other substituted phenols may be used instead of p-tert-butylphenol in this method. These include phenols substituted with groups R3 and / or R4 as defined above. That is, these groups may be independently selected from C1-C10 branched or straight-chain alkyl, C1-C10 branched or straight-chain alkenyl, C1-C10 branched or straight-chain alkoxy, C1-C10 branched or straight-chain hydroxyalkyl, branched or straight-chain C1-C10 alkyl ether, or mixtures thereof. C1-C10 alkyl, C1-C10 alkenyl, C1-C10 alkoxy, and C1-C10 hydroxyalkyl may be selected, for example, from C2-C9, C3-C7, or C4 to C6.

[0081] Example

[0082] Examples 1 and 2 and Comparative Examples 1 and 2

[0083] In Example 1, the first 2-ethylhexyl diphenyl phosphate was synthesized as follows.

[0084] Step I.

[0085] Phosphorus oxychloride (153.3 g, 1.00 mol) was charged into a 1-liter flask and cooled to 10°C. Under vacuum, 2-ethylhexanol (143.3 g, 1.10 mol) was added to the flask at a rate maintaining the temperature below 15°C. The mixture was held and stirred under a vacuum of 30–50 mmHg for 30 minutes to allow the 2-ethylhexanol and phosphorus oxychloride to react fully at <=15°C, then heated to 35°C and held under vacuum for 1.5 hours. The vacuum was released, and the dichloroester was transferred to a feeding funnel.

[0086] Steps II / III.

[0087] In another 1-liter flask, water (167 g) and 50% sodium hydroxide (166.4 g, 2.08 mol) were mixed and cooled to 20°C. Phenol (189.2 g, 2.01 mol) was added to this alkaline solution, keeping the temperature below 40°C. After cooling the resulting sodium phenolate solution to 20°C, the above-mentioned dichloroester (254 g) was added while maintaining the temperature at 25°C. This addition should take 30 minutes. The mixture was stirred at 22-25°C for 45 minutes.

[0088] Initial separation.

[0089] Dilute the reaction mixture with water and adjust the pH to 10-11 by adding 38% HCl (16g). After stirring at 25°C for 5 minutes, allow the mixture to precipitate and separate the phases: the lower layer is aqueous; the upper layer is the product. Remove the lower aqueous layer to obtain the upper product layer.

[0090] Washing steps.

[0091] The oily product was then subjected to a series of six washes, the second of which was an alkaline wash using sodium hydroxide (170 g), and the remainder were water washes. After each stage, the mixture was allowed to settle and the aqueous layer was removed.

[0092] Steam stripping process.

[0093] In a 1-liter flask, the washed oil was steam-stripped at 120-130°C under a vacuum of 80-110 mmHg for 15 minutes. Then the steam was turned off, and the contents were dried at 120-130°C under a vacuum of 30-50 mmHg for 5 minutes. After cooling the contents to 80°C, the vacuum was released. 329 g of product was obtained.

[0094] Analysis of the product composition showed that 2-ethylhexyl diphenyl phosphate accounted for 90.96% and triphenyl phosphate accounted for 0.022%, which is much lower than 0.1%.

[0095] Using the same process steps outlined in Example 1, another example (Example 2) and a comparative example (Comparative Example 1) were attempted. The table below summarizes the product composition (by GC) of these reactions and the commercially available product prepared on-site (Comparative Example 2).

[0096] Table 1 shows the reaction conditions, yields, product distribution determined by GC area method, and TPP content in Examples 1 and 2, as well as Comparative Examples 1 and 2.

[0097] Table 1

[0098] In Comparative Example 1, where the molar ratio of 2-ethylhexanol to POCl3 was 1.05, the holding time at the end of step 1 was 30 minutes, and the final composition had a TPP% of 0.200%, which is above the threshold of 0.1%. This indicates that simply increasing the holding time to 30 minutes and the molar ratio of alcohol to POCl3 to 1.05 at the end of step 1 is insufficient to reduce the TPP% to <0.1%.

[0099] In Comparative Example 2, a production sample including Santicizer® 141 (2-ethylhexyl diphenyl phosphate) was used, with an alcohol to POCl3 molar ratio of 1.02 and a holding time of 4 minutes at the end of step 1. Under these conditions, the percentage of TPP was 0.705%, well above the threshold of 0.1%.

[0100] Example 3 and Comparative Examples 3 and 4

[0101] In Example 3, the first isodecyl diphenyl phosphate was synthesized as follows.

[0102] Step I.

[0103] Add phosphorus oxychloride (140.0 g, 0.913 mol) to a 1-liter flask and cool to 10°C. Under vacuum, add isodecanol (160.0 g, 1.004 mol) to the flask at a rate that keeps the temperature below 15°C. Maintain and stir the mixture under a vacuum of 30–50 mmHg for 30 minutes to allow the isodecanol and phosphorus oxychloride to react fully, then heat to 35°C over 30 minutes and maintain at 35°C for 1.5 hours. Remove the vacuum and transfer the dichloroester to a feeding funnel.

[0104] Steps II / III.

[0105] In another 1-liter flask, water (152 g) and 50% sodium hydroxide (152.0 g, 1.900 mol) were mixed and cooled to 20°C. Phenol (172.7 g, 1.835 mol) was added to this alkaline solution, keeping the temperature below 40°C. After cooling the resulting sodium phenolate solution to 20°C, the aforementioned dichloroester (254 g) was added while maintaining the temperature at 25°C. This addition took 27 minutes. The mixture was stirred at 22-25°C for 45 minutes.

[0106] Initial separation.

[0107] Dilute the reactants with water (200g) and adjust the pH to 10-11 by adding 38% HCl (16g). After stirring at 25°C for 5 minutes, allow the mixture to precipitate and separate the phases: the lower layer is aqueous; the upper layer is the product. Remove the bottom aqueous layer to obtain the product layer.

[0108] Washing steps.

[0109] The oily product underwent six washes, the second being an alkaline wash using sodium hydroxide, with all other washes being water washes. During each wash, the mixture was allowed to settle and separate into phases. The aqueous layer was then removed.

[0110] Steam stripping.

[0111] In a 1-liter flask, the washed oil was steam-stripped at 120-130°C under a vacuum of 80-110 mmHg for 15 minutes. Then the steam was turned off, and the contents were dried at 120-130°C under a vacuum of 30-50 mmHg for 5 minutes. After cooling the contents to 80°C, the vacuum was released. 321 g of product was obtained.

[0112] The product's TPP percentage was tested to be 0.0287% (287 ppm), which is far below the threshold of 0.1%.

[0113] The same process steps outlined in Example 3 were used to attempt the comparative examples (Comparative Example 3). The following table summarizes the product compositions of these reactions (by GC) and the commercially available products prepared at the production site (Comparative Example 4):

[0114] Table 2 shows the reaction conditions, yields, and product distribution by GC area for Example 3, Comparative Example 3, and Comparative Example 4 (production samples).

[0115] Table 2

[0116] In Comparative Example 3, the molar ratio of alcohol to POCl3 was 1.10. However, at approximately 15°C, the hold time at the end of step 1 was only 4 minutes. The percentage of TPP was 0.4%, still well above the 0.1% threshold. On the other hand, the production sample of Santicizer® 148 (isodecyl diphenyl phosphate) showed a ratio of 1.05 at the end of reaction 1, a hold time of 4 minutes, and a TPP content of 0.673%. This indicates that an alcohol to POCl3 ratio >= 1.10 and a prolonged hold time at approximately 15°C provide sufficient time for POCl3 molecules to become monoesters (i.e., dichloroesters).

[0117] Example 4 and Comparative Examples 5 and 6

[0118] Under a vacuum of 50 to 250 torr, an alcohol (a mixture of lauryl alcohol and tetradecyl alcohol) (164.0 g) was added to phosphorus oxychloride (120.0 g) at 10-15°C. The mixture was stirred at 15°C for 30 minutes under a vacuum of 30-50 torr, and then at 35°C for 1.5 hours to obtain a liquid intermediate. While maintaining the temperature at 20 to 25°C, this intermediate was added to a phenol salt solution prepared according to step 2 of Example 1 using 25% NaOH (262 g) and phenol (147.3 g). The mixture was stirred at 22 to 25°C for 45 minutes under conditions where pH > 13.

[0119] The reactants were diluted with water (180 g), and the product oil (375 g) was separated and subjected to a series of washes, including alkaline washing, two washes with dilute HCl, and one wash with water. The washed oil (346 g) was steam stripped and dried under vacuum at 120–130 °C to give 316 g of C12-C16 alkyl diphenyl phosphate. The yield was 95.5%, the color was 1 APHA, and the acidity was 6.135 meq. / 100 g. The total GC area of ​​all products was 99.39%, with triphenyl phosphate accounting for 0.034%.

[0120] In Comparative Example 5, at the end of step 1, the molar ratio of the starting alcohol to POCl3 was 1.02, and the holding time was 30 minutes.

[0121] Comparative Example 6, a production sample of Santicizer® 2148, is chemically a C12-C16 alkyl diphenyl phosphate. When the molar ratio of alcohol to POCl3 was 1.05 and the holding time was 4 minutes, the TPP% was 0.278%.

[0122] Table 3 shows the reaction conditions, yields, and product distribution by GC area for Examples 4 and Comparative Examples 4 and 5.

[0123] Table 3

[0124] Data show that increasing the molar ratio and increasing the holding time at the end of step 1 can effectively reduce TPP% to <0.1%.

[0125] Example 5

[0126] In Example 5, alkyl-substituted triphenyl phosphate was synthesized as follows.

[0127] In a mixture of phosphorus oxychloride (153.3 g) and aluminum chloride (3.0 g) heated to 70 °C, p-tert-butylphenol (262.9 g) was added in portions at 70–95 °C. After further heating the mixture at 125 °C for 2 hours, phenol (117.6 g) was added in portions to the same reactor at 120–125 °C. The mixture was then heated at 125 °C under normal pressure for 3 hours, followed by heating under vacuum (approximately 50 Torr) for 30 minutes. The HCl gas produced by the reaction was absorbed by water.

[0128] The reaction was cooled to 80°C and then treated at 75°C with dilute alkali (430 g, prepared with 400 g water and 30 g 50% NaOH) and gluconic acid (8.0 g) for 1.5 hours.

[0129] Separate the phases and wash the oil layer three times with water until the final pH value reaches 8.

[0130] The washed oil (462 g) was steam stripped and vacuum dried at 120-130 °C to obtain 390 g of the expected product.

[0131] The product yield was 91.9%, with a color of 55 APHA and an acidity of 0.076 meq. / 100g. GC analysis of the product components showed that the TPP content was 0.075%, below the 0.1% threshold. Other product components included p-tert-butylphenyl diphenyl phosphate, di(p-tert-butylphenyl) phosphate, and some tri(p-tert-butylphenyl) phosphate.

[0132] Comparative Example 7

[0133] Partially added p-tert-butylphenol (225.3 g) was added to a mixture of phosphorus oxychloride (153.3 g) and aluminum chloride (3.0 g) heated to 70 °C. After further heating the mixture at 125 °C for 2 hours, phenol (141.2 g) was added in portions at a temperature between 120 and 125 °C. The mixture was then heated at 125 °C under normal pressure for 3 hours, followed by heating under vacuum (approximately 50 Torr) for 30 minutes. The HCl gas produced by the reaction was absorbed by water.

[0134] The reaction was cooled to 80°C and then treated at 72°C with dilute alkali (500 g, prepared with 460 g water and 40 g 50% NaOH) and gluconic acid (8.0 g) for 1.5 hours.

[0135] Separate the phases and wash the oil layer three times with water until the final pH value reaches 9.

[0136] The washed oil (450 g) was steam stripped and vacuum dried at 120 to 130 °C to obtain 393 g of the expected product.

[0137] The product yield was 95.8%, with a color of 8 APHA and an acidity of 0.019 meq. / 100g. GC analysis showed that the TPP content was 0.15%, slightly above the threshold of 0.1%.

[0138] Comparative Example 8

[0139] To a mixture of phosphorus oxychloride (153.3 g) and aluminum chloride (3.0 g) heated to 50 °C, p-tert-butylphenol (180.3 g) was added in portions at temperatures ranging from 50 to 95 °C. The mixture was further heated at 125 °C for 1.5 hours, followed by the addition of phenol (169.4 g) in portions at 120–125 °C. The mixture was then heated at 125 °C under normal pressure for 2.5 hours, followed by heating under vacuum (approximately 50 Torr) for 30 minutes. The HCl gas produced by the reaction was absorbed by water.

[0140] The reaction was cooled to 80°C and then treated at 72°C with a dilute caustic soda (500 g, prepared with 460 g water and 40 g 50% NaOH) and gluconic acid (8.0 g) for 1.5 hours.

[0141] Separate the phases and wash the oil layer three times with water until the final pH value reaches 9.

[0142] The washed oil (404 g) was steam stripped and vacuum dried at 120-130 °C to obtain 368 g of the expected product.

[0143] Yield: 93.5%. Color: 10 APHA. Acidity: 0.040 meq. / 100g. GC analysis showed that the TPP content was 1.31%, far exceeding the threshold of 0.1%.

[0144] Comparative Example 9

[0145] Phosphorus trichloride (153.3 g) was slowly added to a mixture of p-tert-butylphenol (225.3 g) and aluminum chloride (3.0 g) heated to 105 °C at 105 °C, between 105 and 112 °C. After further heating the mixture at 115 °C for 1 hour, phenol (141.2 g) was added in portions. The mixture was then heated at 125 °C under normal pressure for 3 hours, followed by heating under vacuum (approximately 50 Torr) for 30 minutes. The HCl gas produced by the reaction was absorbed by water.

[0146] The reaction was cooled to 80°C and then treated at 70°C with a dilute caustic soda (500 g, prepared with 460 g water and 40 g 50% NaOH) and gluconic acid (8.0 g) for 1.5 hours.

[0147] Separate the phases and wash the oil layer three times with water until the final pH value reaches 9.

[0148] The washed oil (423 g) was steam stripped and vacuum dried at 120-130 °C to obtain 398 g of the expected product.

[0149] The product yield was 97.0%, with a color of 55 APHA and an acidity of 0.014 meq. / 100g. GC analysis showed that the TPP content was 8.46%, significantly higher than the previous two comparative samples.

[0150] All results for Example 5 and Comparative Examples 7-9 are summarized in Table 4 below.

[0151] Table 4

[0152] The results above show that to achieve <0.1% TPP in the desired product, the initial molar ratio of PTBP to POCl3 should be ≥1.65, for example ≥1.75, and the order of addition should be PTBP to POCl3. This synergistically maximizes the chance that each POCl3 molecule will first react with PTBP to form a monoester. In step 2 of the reaction in the same reactor, the amount of unreacted POCl3 is significantly reduced upon the addition of phenol. It is believed that POCl3 reacts with phenol to generate TPP, and in this way, the percentage of TPP in the final product is controlled to <0.1%.

[0153] The foregoing includes examples of one or more embodiments. It is certainly impossible to describe every possible modification and alteration of the above-described apparatus or method in order to describe the foregoing aspects, but those skilled in the art will recognize that many further modifications and arrangements of the aspects are possible. Therefore, the described aspects are intended to cover all such changes, modifications, and variations that fall within the spirit and scope of the appended claims. Furthermore, if the word “comprising” is used in the specific embodiment or claims, the term is intended to be interpreted in a manner similar to the inclusion interpreted as the term “comprising” when used as a transitional word in a claim. The term “consistently comprising” as used herein refers to the specified material or step, and the material or method that does not materially affect the basic and novel characteristics of the material or method. If not specified above, the performance mentioned herein may be determined by applicable ASTM standards, or, if no ASTM standard exists, by the most commonly used standard known to those skilled in the art. Unless the context otherwise requires, the articles “a,” “an,” and “the” shall be interpreted as “one or more.”

Claims

1. A composition comprising: Phosphate ester compounds of formulas 1, 2 and 3 (1) (2) (3) R1 and R2 are independently selected from C4-C18 branched or straight-chain alkyl, C4-C18 branched or straight-chain alkenyl, C4-C18 branched or straight-chain alkoxy, C4-C18 branched or straight-chain hydroxyalkyl, branched or straight-chain C4-C18 alkyl ether or a mixture thereof. The weight of Formula 1 accounts for 75% or more of the total weight of all phosphate esters in the composition; and the weight of Formula 3 is less than 0.1% of the total weight of all phosphate esters in the composition. or Phosphate ester compounds of formulas 4, 5 and 3; (4) (5) R3 and R4 are independently selected from C1-C10 branched or straight-chain alkyl, C1-C10 branched or straight-chain alkenyl, C1-C10 branched or straight-chain alkoxy, C1-C10 branched or straight-chain hydroxyalkyl, branched or straight-chain C1-C10 alkyl ether, or mixtures thereof, and wherein the weight of Formula 3 accounts for less than 0.1% of the total weight of all phosphate esters in the composition.

2. The composition according to claim 1, wherein R1 and R2 are independently selected from branched or straight-chain C4-C18 alkyl or branched or straight-chain C4-C18 alkyl ether groups; or R4 and R5 are independently selected from branched or straight-chain C4-C18 alkyl or branched or straight-chain C4-C18 alkyl ether groups.

3. The composition according to claim 1, wherein R1 and R2 are 2-ethylhexyl.

4. The composition according to claim 1, wherein R1 and R2 are straight-chain or branched C. 10 alkyl.

5. The composition according to claim 1, wherein R1 and R2 are independently selected from linear or branched C-chain compounds. 10 H 21 -C 12 H 25 -C 14 H 29 or -C 16 H 33 Group.

6. The composition according to claim 1, wherein the structure of formula 2 is present at 20% to 1% by weight of all phosphate esters in the composition.

7. The composition according to claim 1, wherein the structure of formula 3 is present at 0.01% to 0.05% by weight of the total compound.

8. The composition according to claim 1, wherein R3 and / or R4 are tert-butyl.

9. A polymer composition comprising: (a) Polymers selected from polyvinyl chloride (PVC), polyurethane, polyvinyl acetate, polyvinyl butyral, polystyrene, nitrocellulose, nitrile rubber, ABS, polycarbonate, polyamide, polyester, epoxy resin, and combinations thereof; and (b) A phosphate ester composition comprising Phosphate ester compounds of formulas 1, 2 and 3 (1) (2) (3) R1 and R2 are independently selected from C4-C18 branched or straight-chain alkyl, C4-C18 branched or straight-chain alkenyl, C4-C18 branched or straight-chain alkoxy, C4-C18 branched or straight-chain hydroxyalkyl, branched or straight-chain C4-C18 alkyl ether or a mixture thereof. Formula 1 comprises 75% of the total weight of all phosphate esters in the composition; and Formula 3 comprises less than 0.1% of the total weight of all phosphate esters in the composition. or Phosphate ester compounds of formulas 4, 5 and 3; (4) (5) R3 and R4 are independently selected from C1-C10 branched or straight-chain alkyl, C1-C10 branched or straight-chain alkenyl, C1-C10 branched or straight-chain alkoxy, C1-C10 branched or straight-chain hydroxyalkyl, branched or straight-chain C1-C10 alkyl ether, or mixtures thereof, wherein the weight of Formula 3 is less than 0.1% of the total weight of all phosphate esters in the composition.

10. The composition according to claim 9, wherein the polymer is selected from PVC and polyurethane.

11. The composition according to claim 9, wherein R1 and R2 are independently selected from straight-chain or branched C4-C18 alkyl or branched or straight-chain C4-C18 alkyl ether groups; or R4 and R5 are independently selected from branched or straight-chain C1-C10 alkyl or branched or straight-chain C1-C10 alkyl ether groups.

12. The composition according to claim 9, wherein R1 and R2 are independently selected from 2-ethylhexyl, straight-chain or branched-C 10 H 21 -C 12 H 25 -C 14 H 29 or -C 16 H 33 Group; or R3 and / or R4 are tert-butyl groups.

13. A method for preparing a phosphate ester with a low triphenyl phosphate content, the method comprising: An alcohol having the formula R0OH is reacted with POCl3 to produce a reaction mixture containing an intermediate; The alcohol having the formula R0OH is provided with POCl3 in a molar ratio of ≥1.10 to 1; Wherein R0 is selected from the following alkyl groups: C4-C18 branched or straight-chain alkyl, C4-C18 branched or straight-chain alkenyl, C4-C18 branched or straight-chain alkoxy, C4-C18 branched or straight-chain hydroxyalkyl, branched or straight-chain C4-C18 alkyl ether, or a mixture thereof. An intermediate is reacted with a phenolic compound to form a composition comprising a phosphate monoester, said phosphate monoester comprising an alkyl group corresponding to R0; or The substituted phenol is reacted with POCl3, wherein the phenol is substituted by substituent groups R3 and / or R4; The substituted phenol is provided with POCl3 in a molar ratio of ≥1.65:1; R3 and R4 are independently selected from C1-C10 branched or straight-chain alkyl, C1-C10 branched or straight-chain alkenyl, C1-C10 branched or straight-chain alkoxy, C1-C10 branched or straight-chain hydroxyalkyl, branched or straight-chain C1-C10 alkyl ether, or mixtures thereof.

14. The method of claim 13, wherein the composition comprises less than 0.1% by weight of triphenyl phosphate of the total phosphate ester.

15. The method according to claim 13, wherein after the step of reacting the alcohol having the formula R0OH with POCl3, the reaction is maintained for 15 minutes after adding all the alcohol and POCl3, and then the step of reacting the intermediate with the phenolic compound is continued.

16. The method according to claim 13, wherein after the step of reacting the alcohol having the formula R0OH with POCl3, the reaction is maintained at a temperature of 1°C to 20°C.

17. The method according to claim 13, wherein in the step of reacting an alcohol having the formula R0OH with POCl3, the temperature of the step is maintained at 1 to 20°C.

18. The method of claim 13, wherein the step of reacting the alcohol of formula R0OH with POCl3 is carried out under partial vacuum, or under partial vacuum after the addition of the substituted phenol.

19. The method according to claim 13, wherein the phosphate composition comprises a phosphate compound of formula 1, formula 2 and formula 3. (1) (2) (3) R1 and R2 are independently selected from C4-C18 branched or straight-chain alkyl, C4-C18 branched or straight-chain alkenyl, C4-C18 branched or straight-chain alkoxy, C4-C18 branched or straight-chain hydroxyalkyl, branched or straight-chain C4-C18 alkyl ether or a mixture thereof. The weight of Formula 1 is 75% of the total weight of the phosphate ester compounds in the composition; and the weight of Formula 3 is less than 0.1% of the total weight of the phosphate ester compounds in the composition. or Phosphate ester compounds of formulas 4, 5 and 3; (4) (5) The weight of Formula 3 is less than 0.1% of the total weight of the phosphate ester compound in the composition.

20. The method according to claim 13, wherein the substituted phenol reacts with POCl3, and the molar ratio of the substituted phenol to POCl3 is 1.75:1 to 2.5:1; and The order of addition is to add the substituted phenol to POCl3.

Images