Isomerically directed phosphate ester fire resistant fluid compositions and methods for making same

Abstract

The application discloses a phosphate ester fire-resistant oil composition with isomer directional regulation and a preparation method thereof, and particularly relates to the technical field of hydraulic oil, which comprises a directional regulation type tri (dimethylphenyl) phosphate ester, a directional regulation type tertiary butyl phenyl phosphate ester, a chlorine capturing agent, a composite antioxidant, an antifoaming agent and a metal deactivator. The product has an ultralow chlorine content, excellent antifoaming property and air release property, and the comprehensive performance meets the requirements of the electro-hydraulic regulating system of a power plant steam turbine, through isomer directional screening and para-substitution regulation, combined with catalyst-free esterification and complex chlorine capturing.

Description

Technical Field

[0001] This invention relates to the field of hydraulic fluid technology, and more specifically, to isomer-directed controlled phosphate ester fire-resistant oil compositions and their preparation methods. Background Technology

[0002] Phosphate ester fire-resistant oils are widely used in the electro-hydraulic control systems of power plant turbines due to their excellent high-temperature fire resistance, lubricity, and thermal stability. Currently, mainstream phosphate ester fire-resistant oil products at home and abroad are mainly divided into two categories: one is based on tris(xylyl) phosphate (TXP), and the other is based on tert-butylphenyl phosphate (TBPP).

[0003] Tris(xylyl) phosphate possesses excellent air release and anti-foaming properties, but its reproductive toxicity limits its use. While tert-butylphenyl phosphate lacks reproductive toxicity, its poor foaming performance restricts its use alone. To combine the advantages of both, existing technologies have attempted to use them in combination. For example, Chinese patent CN103224825B discloses a medium-pressure fire-resistant oil with trisylyl phosphate as the base oil and its production method. This technical solution combines trisylyl phosphate with di(tert-butylphenyl) phosphate, but it does not address the fine-tuning of the xylenol isomer composition, nor does it control the tert-butyl substitution degree distribution in tert-butylphenyl phosphate.

[0004] Industrial xylenol has six isomers. Phosphate esters synthesized from different isomers exhibit significant differences in viscosity, air release properties, and foaming characteristics, directly determining the key performance indicators of TXP base oils. However, current research on the relationship between xylenol isomer composition and TXP performance is insufficient. Existing domestically produced TXP products still lag behind imported products in terms of chlorine content, anti-foaming properties, and air release properties. Furthermore, Chinese patent CN120904937A discloses a phosphate ester-based fire-resistant oil with synergistic optimization of fire resistance and stability, and its preparation method. This technical solution synthesizes phosphate esters by controlling the isomer content in mixed alkylphenols, but its isomer control parameters differ from those in this application, and it does not involve compounding with tert-butylphenyl phosphate.

[0005] Therefore, how to obtain a high-performance phosphate ester fire-resistant oil composition with excellent anti-foaming properties, air release properties, and low chlorine content through targeted screening of xylenol isomers and precise control of tert-butylphenyl phosphate is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To overcome the aforementioned deficiencies of the prior art, the present invention provides the following technical solution: On one hand, the present invention provides an isomer-directed controlled phosphate ester fire-resistant oil composition comprising the following components in parts by weight: Component A: Directionally regulated tris(xylyl) phosphate, 50–75 parts; Component B: Directionally regulated tert-butylphenyl phosphate, 25-50 parts; Chlorine scavenger: 0.2–0.8 parts; Compound antioxidant: 0.3–1.2 parts; Antifoaming agent: 0.001–0.01 parts; Metal passivating agent: 0.01–0.05 parts; Component A is tris(xylyl) phosphate, whose isomer composition derived from xylenol satisfies the following: the molar ratio of 2,4-xylyl to 2,5-xylyl is 1.2:1 to 2.5:1. Based on the total amount of all xylyl groups in the tris(xylyl) phosphate, the content of 2,6-xylyl is ≤3.5wt%, and the content of 3,5-xylyl is ≤2.0wt%. In component B, the content of mono-tert-butyltriphenyl phosphate is 45wt% to 55wt%, the content of di-tert-butyltriphenyl phosphate is 35wt% to 45wt%, and the content of tri-tert-butyltriphenyl phosphate is ≤8wt%.

[0007] Preferably, in component A, the content of 2,3-xylyl group is ≤1.5 wt%, and the content of 3,4-xylyl group is ≤1.5 wt%. The content of para-substituted tert-butyl triphenyl phosphate in component B is ≥70wt%, the content of ortho-substituted tert-butyl triphenyl phosphate is ≤30wt%, and the content of triphenyl phosphate in component B is ≤1.5wt%.

[0008] Preferably, the chlorine scavenger is a compound of epoxidized soybean oil and glycidyl ether compounds, with a mass ratio of 3 to 5:1.

[0009] Preferably, the composite antioxidant is a ternary compound of 2,6-di-tert-butyl-p-cresol, phenyl-α-naphthylamine, and phosphite antioxidant, with a mass ratio of 2-4:1-2:0.5-1.

[0010] Preferably, the antifoaming agent is an acrylate polymer, and the metal passivating agent is benzotriazole or methylbenzotriazole.

[0011] Preferably, the composition further comprises a dispersant, which is a polyisobutylene succinimide compound, specifically monosuccinimide or bissuccinimide, in an amount of 0.02 to 0.10 parts by weight.

[0012] On the other hand, the present invention also provides a method for preparing an isomer-directed controlled phosphate ester fire-resistant oil composition, comprising the following steps: S1. Select industrial xylenol as raw material, and adjust the mass ratio of 2,4-xylenol to 2,5-xylenol to 1.2:1 to 2.5:1 by distillation, control the content of 2,6-xylenol to ≤3.5wt% and the content of 3,5-xylenol to ≤2.0wt%. Use the adjusted mixed xylenol as raw material, and carry out esterification reaction with phosphorus oxychloride at a molar ratio of 3.2 to 3.5:1 under catalyst-free conditions. The reaction temperature is 145 to 155℃ and the reaction time is 8 to 12 hours. After the reaction, the product is washed with water, washed with alkali, distilled under reduced pressure and purified by molecular sieve to obtain component A. S2. Using triphenyl phosphate as a raw material, an alkylation reaction is carried out with isobutylene in the presence of a para-selective Lewis acid catalyst, with the reaction temperature controlled at 75–85 °C, to obtain component B, wherein the content of para-substituted tert-butyl triphenyl phosphate is ≥70 wt%. S3. Mix component A and component B in proportion, add chlorine scavenger, compound antioxidant, antifoaming agent, metal passivator and optional dispersant, stir and refine, filter to obtain the final product.

[0013] Preferably, in step S1, the distillation separation uses a distillation column with ≥60 theoretical plates and a reflux ratio of 8:1 to 15:1.

[0014] Preferably, the para-selective Lewis acid catalyst in step S2 is a complex of aluminum trichloride and an organic amine or a supported boron trifluoride catalyst.

[0015] The technical effects and advantages of this invention are as follows: This invention is the first to target and regulate the proportion of key isomers in xylenol, a raw material for tris(xylyl) phosphate, while precisely controlling the content and para-substitution ratio of mono-tert-butyl, di-tert-butyl, and tri-tert-butyl in tert-butylphenyl phosphate. This results in a significant synergistic effect when the two base oils are blended, and the resulting fire-resistant oil exhibits excellent anti-foaming and air-release properties. This effectively solves the industry problem of poor foaming performance when tert-butylphenyl phosphate is used alone. Furthermore, by limiting the content of isomers such as 2,6-xylenol and 3,5-xylenol, which may be associated with toxicity, the potential reproductive toxicity risk of tris(xylyl) phosphate is significantly reduced, enabling it to have higher safety while ensuring excellent performance. This overcomes the technical barrier that restricts its application due to toxicity issues. This invention employs a catalyst-free esterification process to synthesize tris(xylyl) phosphate, combined with molecular sieve refining, thus avoiding the introduction of metal ions and organochlorine impurities at the source. Simultaneously, it utilizes a chlorine-capturing system composed of epoxidized soybean oil and glycidyl ether. Through the synergistic effect of organochlorine capture and inorganic chlorine complexation, the product achieves ultra-low chlorine content, far superior to commercially available domestic products and existing technical formulations, fully meeting the stringent requirements of power plant electro-hydraulic control systems for oil chlorine content. This invention employs a ternary composite antioxidant system composed of hindered phenolic, amine, and phosphite antioxidants. The three types of antioxidants have complementary mechanisms of action, significantly extending the oxidation induction period of the product. Simultaneously, it is combined with acrylate antifoaming agents and polyisobutylene succinimide dispersants, giving the composition comprehensive properties such as high auto-ignition point and high resistivity. This fully meets and exceeds the requirements of relevant industry standards and can simultaneously meet the certification requirements of several major international turbine manufacturers for oils used in power plant electro-hydraulic control systems. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the overall steps of the present invention.

[0017] Figure 2 The gas chromatogram of component A prepared in Example 1 of the present invention shows its isomer composition.

[0018] Figure 3 The high-performance liquid chromatogram of component B prepared in Example 1 of the present invention shows the distribution of its tert-butyl groups.

[0019] Figure 4 The image shows a comparison of the appearance of the fire-resistant oil composition prepared in Example 1 of this invention with imported TXP and commercially available domestic TXP.

[0020] Figure 5 The image shows a comparison test of the foam performance of the fire-resistant oil composition prepared in Example 1 of this invention with imported TXP and commercially available domestic TXP. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Example 1

[0022] like Figure 1 As shown, this embodiment provides a phosphate ester fire-resistant composition with isomer-directed regulation, and its preparation method is as follows: S1, Preparation of component A Industrial xylenol was selected as the raw material and separated and regulated by distillation. A distillation column with 65 theoretical plates and a reflux ratio of 12:1 was used. After regulation, the mass ratio of 2,4-xylenol to 2,5-xylenol in the mixed xylenol was 1.8:1, the content of 2,6-xylenol was 2.8 wt%, the content of 3,5-xylenol was 1.5 wt%, the content of 2,3-xylenol was 0.8 wt%, and the content of 3,4-xylenol was 0.6 wt%. 1000 kg of the above-modified mixed xylenol was added to a reaction vessel with phosphorus oxychloride at a molar ratio of 3.3:1. Esterification was carried out under catalyst-free conditions at 150°C for 10 hours. After the reaction, the mixture was successively washed with water, washed with 5 wt% sodium carbonate solution, distilled under reduced pressure at 180°C and 1 kPa, and then purified by molecular sieve adsorption to obtain 1120 kg of component A. The gas chromatogram of component A is shown below. Figure 2 As shown, its isomer composition satisfies the following: the molar ratio of 2,4-xylyl to 2,5-xylyl is 1.8:1. Based on the total amount of xylyl groups in tris(xylyl)phosphate, the content of 2,6-xylyl is 2.8 wt%, the content of 3,5-xylyl is 1.5 wt%, the content of 2,3-xylyl is 0.8 wt%, and the content of 3,4-xylyl is 0.6 wt%. Analysis revealed that component A has a chlorine content of 7 ppm, an acid value of 0.03 mg KOH / g, and a moisture content of 85 ppm.

[0023] S2, Preparation of Component B 1000 kg of triphenyl phosphate was added to a reactor, along with a para-selective Lewis acid catalyst, a complex of aluminum trichloride and triethylamine, at a molar ratio of 1:0.5. The mixture was heated to 80°C, and isobutylene was slowly introduced to initiate an alkylation reaction. The reaction was monitored online by chromatography. The reaction was terminated when the content of mono-tert-butyltriphenyl phosphate reached 51%. After the reaction, the mixture was neutralized, washed with water, and distilled under reduced pressure to obtain 1180 kg of component B. The high-performance liquid chromatogram of component B is shown below. Figure 3 As shown, liquid chromatography analysis revealed that component B contained 51 wt% mono-tert-butyltriphenyl phosphate, 41 wt% di-tert-butyltriphenyl phosphate, 6 wt% tri-tert-butyltriphenyl phosphate, 78 wt% para-substituted tert-butyltriphenyl phosphate, 18 wt% ortho-substituted tert-butyltriphenyl phosphate, and 0.9 wt% triphenyl phosphate.

[0024] S3, compound Take 65 parts by weight of component A and 35 parts by weight of component B and add them to a mixing vessel. Heat the mixture to 60°C and stir for 1.5 hours. Then add 0.4 parts by weight of chlorine scavenger, 0.5 parts by weight of compound antioxidant, 0.003 parts by weight of antifoaming agent, 0.02 parts by weight of metal passivator, and 0.05 parts by weight of dispersant. Continue stirring for 2 hours. The chlorine scavenger is a compound of epoxidized soybean oil and allyl glycidyl ether in a mass ratio of 4:1. The compound antioxidant is a compound of 2,6-di-tert-butyl-p-cresol, phenyl-α-naphthylamine, and tris(2,4-di-tert-butylphenyl) phosphite in a mass ratio of 3:1.5:0.8. The antifoaming agent is an acrylate polymer. The metal passivator is benzotriazole. The dispersant is monosuccinimide.

[0025] After stirring, the mixture is filtered through a 3μm precision filter and discharged to obtain a fire-resistant oil composition. Figure 4 and Figure 5 As shown, the fire-resistant oil composition prepared in this embodiment is clear and transparent in appearance, and its foaming performance (20 / 0 ml) is significantly better than that of the comparative sample. Example 2

[0026] The difference between this embodiment and Embodiment 1 is that the weight ratio of component A to component B is 55:45. In the raw material xylenol of component A, the mass ratio of 2,4-xylenol to 2,5-xylenol is 1.5:1, the content of 2,6-xylenol is 3.0 wt%, and the content of 3,5-xylenol is 1.8 wt%. Correspondingly, in the finished product component A, the molar ratio of 2,4-xylyl to 2,5-xylyl is 1.5:1, the content of 2,6-xylyl is 3.0 wt%, and the content of 3,5-xylyl is 1.8 wt%.

[0027] Component B contains 48 wt% mono-tert-butyl phosphate, 43 wt% di-tert-butyl phosphate, and 7 wt% tri-tert-butyl phosphate.

[0028] Under the same conditions as in Example 1, an oil-resistant composition was prepared. Example 3

[0029] The difference between this embodiment and Embodiment 1 is that: the proportion of phosphite antioxidants is increased in the compound antioxidant, and the mass ratio of the three is 2:1:1; the mass ratio of epoxidized soybean oil to glycidyl ether in the chlorine scavenger is 5:1; and no dispersant is added.

[0030] Under the same conditions as in Example 1, an oil-resistant composition was prepared.

[0031] Comparative Example 1 A commercially available domestic TXP fire-resistant oil was selected, which is labeled as conforming to the DL / T 571 standard.

[0032] Comparative Example 2 We selected commercially available imported TXP fire-resistant oil (Lanxess 46SJ).

[0033] Comparative Example 3 Select commercially available imported TBPP fire-resistant oil (Lanxess 46B).

[0034] Comparative Example 4 The difference from Example 1 is that the xylenol raw material used in component A was not controlled by isomers, but directly used commercially available industrial xylenol, wherein the mass ratio of 2,4-xylenol to 2,5-xylenol was 0.6:1, the content of 2,6-xylenol was 11.5 wt%, and the other synthesis processes were the same as in Example 1, and a comparative sample was prepared.

[0035] Comparative Example 5 Referring to the formulation of Example 1 in CN103224825B: Take 60 parts of trimethylol phosphate, 40 parts of di(tert-butylphenyl)phenyl phosphate, add 0.9 parts of epoxidized soybean oil octyl ester and 0.4 parts of benzotriazole, mix evenly and filter to prepare the comparative sample.

[0036] Performance testing: The performance of the samples from Examples 1-3 and Comparative Examples 1-5 were tested according to the methods specified in DL / T 571-2014 "Guidelines for Operation and Maintenance of Phosphate Ester Fire-Resistant Oil for Power Plants".

[0037] The test items include appearance, chlorine content, acid value, moisture, kinematic viscosity at 40℃, autoignition point, air release (50℃), foam characteristics (foam tendency / foam stability), and resistivity (20℃).

[0038] The test results are shown in the table below: Appearance transparent transparent transparent transparent Slightly cloudy transparent transparent transparent transparent Chlorine content (ppm) ≤50 7 8 6 42 8 5 28 15 Acid value (mgKOH / g) ≤0.1 0.03 0.04 0.03 0.09 0.04 0.03 0.07 0.06 Moisture content (ppm) ≤1000 85 92 80 210 95 80 180 150 Kinematic viscosity at 40℃ (mm² / s) 41.4-50.6 46.8 46.2 46.5 49.5 47.2 44.5 48.1 47.5 Autoignition point (°C) ≥530 615 610 618 580 620 590 595 600 Air release (50°C, min) ≤10 3.2 3.8 3.0 9.2 3.5 13.5 7.8 6.5 Foam properties (ml / ml) Report 20 / 0 25 / 0 18 / 0 115 / 15 25 / 0 260 / 40 85 / 5 70 / 5 Resistivity (20℃, Ω·cm) Report <![CDATA[8.5×10 9 ]]> <![CDATA[7.8×10 9 ]]> <![CDATA[8.9×10 9 ]]> <![CDATA[3.2×10 9 ]]> <![CDATA[9.1×10 9 ]]> <![CDATA[8.8×10 9 ]]> <![CDATA[5.6×10 9 ]]> <![CDATA[6.2×10 9 ]]> As shown in the table above, the fire-resistant oil compositions prepared in Examples 1-3 of this invention exhibit excellent overall performance. The chlorine content is ≤8 ppm, significantly lower than Comparative Example 1 (42 ppm) and Comparative Example 5 (15 ppm); the foaming properties are ≤25 / 0 ml, far superior to Comparative Example 1 (115 / 15 ml), Comparative Example 3 (260 / 40 ml), and Comparative Example 5 (70 / 5 ml); the air release is ≤3.8 min, superior to Comparative Example 1 (9.2 min), Comparative Example 3 (13.5 min), and Comparative Example 5 (6.5 min). Example 3, due to the use of a higher proportion of phosphite antioxidants, maintains good dispersion stability even without the addition of a dispersant.

[0039] Comparative Example 4 (TXP without controlled isomers) had a chlorine content of 28 ppm, a foaming property of 85 / 5 ml, and an air release rate of 7.8 min, all of which were inferior to Example 1 and the imported TXP, demonstrating the key impact of directional control of xylenol isomers on product performance.

[0040] The comparison of the above examples and comparative examples shows that the present invention, through precise control of the proportion of specific isomers in xylenol, a raw material for TXP, and regulation of the degree of substitution of tert-butyl and the proportion of para-substitution in TBPP, combined with a catalyst-free esterification process, a ternary composite antioxidant, and a compound chlorine scavenger, achieves excellent comprehensive performance with chlorine content ≤10ppm, foam characteristics ≤30 / 0ml, air release ≤4min, and auto-ignition point ≥600℃. All indicators fully meet and exceed the requirements of the DL / T 571-2014 standard.

[0041] The phosphate ester fire-resistant oil composition of the present invention is suitable for the electro-hydraulic control system (EHC) of power plant turbines and can meet the certification requirements of OEM manufacturers such as GE, Westinghouse, Alstom / ABB, and Siemens, and has broad application prospects.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A phosphate ester fire-resistant oil composition with isomer-directed regulation, characterized in that: The components comprise the following parts by weight: Component A: Directionally regulated tris(xylyl) phosphate, 50–75 parts; Component B: Directionally regulated tert-butylphenyl phosphate, 25-50 parts; Chlorine scavenger: 0.2–0.8 parts; Compound antioxidant: 0.3–1.2 parts; Antifoaming agent: 0.001–0.01 parts; Metal passivating agent: 0.01–0.05 parts; Component A is tris(xylyl) phosphate, whose isomer composition derived from xylenol satisfies the following: the molar ratio of 2,4-xylyl to 2,5-xylyl is 1.2:1 to 2.5:

1. Based on the total amount of all xylyl groups in the tris(xylyl) phosphate, the content of 2,6-xylyl is ≤3.5wt%, and the content of 3,5-xylyl is ≤2.0wt%. In component B, the content of mono-tert-butyltriphenyl phosphate is 45wt% to 55wt%, the content of di-tert-butyltriphenyl phosphate is 35wt% to 45wt%, and the content of tri-tert-butyltriphenyl phosphate is ≤8wt%.

2. The composition according to claim 1, characterized in that: In component A, the content of 2,3-xylyl group is ≤1.5 wt%, and the content of 3,4-xylyl group is ≤1.5 wt%. The content of para-substituted tert-butyl triphenyl phosphate in component B is ≥70wt%, the content of ortho-substituted tert-butyl triphenyl phosphate is ≤30wt%, and the content of triphenyl phosphate in component B is ≤1.5wt%.

3. The composition according to claim 1, characterized in that: The chlorine-catching agent is a compound of epoxidized soybean oil and glycidyl ether compounds, with a mass ratio of 3 to 5:

1.

4. The composition according to claim 1, characterized in that: The composite antioxidant is a ternary compound of 2,6-di-tert-butyl-p-cresol, phenyl-α-naphthylamine, and phosphite antioxidant, with a mass ratio of 2-4:1-2:0.5-1.

5. The composition according to claim 1, characterized in that: The antifoaming agent is an acrylate polymer, and the metal passivating agent is benzotriazole or methylbenzotriazole.

6. The composition according to claim 1, characterized in that: The composition also includes a dispersant, which is a polyisobutylene succinimide compound, specifically monosuccinimide or bissuccinimide, in an amount of 0.02 to 0.10 parts by weight.

7. A method for preparing a phosphate ester fire-resistant composition with isomer-directed regulation as described in any one of claims 1 to 6, characterized in that: Includes the following steps: S1. Select industrial xylenol as raw material, and adjust the mass ratio of 2,4-xylenol to 2,5-xylenol to 1.2:1 to 2.5:1 by distillation, control the content of 2,6-xylenol to ≤3.5wt% and the content of 3,5-xylenol to ≤2.0wt%. Use the adjusted mixed xylenol as raw material, and carry out esterification reaction with phosphorus oxychloride at a molar ratio of 3.2 to 3.5:1 under catalyst-free conditions. The reaction temperature is 145 to 155℃ and the reaction time is 8 to 12 hours. After the reaction, the product is washed with water, washed with alkali, distilled under reduced pressure and purified by molecular sieve to obtain component A. S2. Using triphenyl phosphate as a raw material, an alkylation reaction is carried out with isobutylene in the presence of a para-selective Lewis acid catalyst, with the reaction temperature controlled at 75–85 °C, to obtain component B, wherein the content of para-substituted tert-butyl triphenyl phosphate is ≥70 wt%. S3. Mix component A and component B in proportion, add chlorine scavenger, compound antioxidant, antifoaming agent, metal passivator and optional dispersant, stir and refine, filter to obtain the final product.

8. The preparation method according to claim 7, characterized in that: In step S1, the distillation separation uses a distillation column with ≥60 theoretical plates and a reflux ratio of 8:1 to 15:

1.

9. The preparation method according to claim 7, characterized in that: In step S2, the para-selective Lewis acid catalyst is a complex of aluminum trichloride and an organic amine or a supported boron trifluoride catalyst.

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