Method for reducing color number of high-color-number yellowed trioctyl trimellitate

Abstract

The invention relates to the technical field of fine chemical decolorization, and particularly discloses a method for reducing the color number of high-color-number yellowed trioctyl trimellitate, which comprises the following steps: S1, adding high-color-number yellowed trioctyl trimellitate into a reaction kettle, stirring and heating; s2, slowly adding a hydrogen peroxide solution for decolorization reaction, stirring, heating and preserving heat; s3, after heat preservation is finished, slowly adding a dilute alkali solution, stirring and preserving heat; s4, transferring the reaction liquid to a separating funnel after neutralization, and standing for layering to obtain an upper organic phase; s5, carrying out negative pressure rectification on the upper organic phase to remove water and light components; and S6, after dehydration, adding activated carbon and decolorizing resin, stirring and decolorizing, and filtering while hot to obtain a low-color-number trioctyl trimellitate product. According to the method, the color number of the high-color-number yellowed trioctyl trimellitate can be effectively reduced from high color number 140-180 to low color number 60-70, waste is turned into wealth, the utilization rate of resources is increased, and trioctyl trimellitate with various indexes meeting industrial indexes can be obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fine chemical decolorization, and particularly relates to a method for reducing the color number of high-color-number yellowish trimellitic acid trioctyl ester. BACKGROUND

[0002] Trimellitic acid trioctyl ester is a heat-resistant and durable main plasticizer, which has the advantages of polyester plasticizer and monomer plasticizer, and has better compatibility, processability, low temperature resistance and electrical properties than polyester plasticizer, and is mainly used in 105 DEG C heat-resistant wire and cable materials and other products requiring heat resistance and durability, such as sheets, sheets, sealing pads, etc., and is also suitable for various plastics such as chlorovinyl copolymer, nitrocellulose, ethyl cellulose, polymethyl methacrylate, etc. With the increasingly stringent safety standards of building and automobile wire and cable heat resistance in China in the future, trioctyl ester will gradually replace phthalate plasticizer, and its demand will grow at an average annual rate of 8%, so its development prospect is very good.

[0003] In industry, trimellitic acid trioctyl ester is synthesized by direct esterification of octanol and trimellitic anhydride, which makes the reaction smooth and fast, and the process is mature. However, the instability of trimellitic anhydride can cause the color of the produced trimellitic acid trioctyl ester to turn yellow, and during storage in the warehouse, due to improper storage, the trimellitic acid trioctyl ester is oxidized, causing the color to become darker, such as yellow, which affects the use of the product.

[0004] Therefore, it is of great practical significance to develop a high-efficiency, environmentally friendly and non-harmful high-color-number trimellitic acid trioctyl ester decolorization method. SUMMARY

[0005] The purpose of the present application is to provide a method for reducing the color number of high-color-number yellowish trimellitic acid trioctyl ester, which can effectively reduce the color number of high-color-number yellowish trimellitic acid trioctyl ester from 140-180 to 60-80. The present application is environmentally friendly, waste is turned into treasure, the utilization rate of resources is improved, and low-color-number trimellitic acid trioctyl ester meeting the industry standards in all aspects can be obtained. By controlling the concentration of hydrogen peroxide, the degradation of the color-developing group is promoted while avoiding affecting the trimellitic acid trioctyl ester, thereby ensuring the quality of the low-color-number trimellitic acid trioctyl ester.

[0006] To solve the above technical problems, the present application provides a method for reducing the color number of high-color-number yellowish trimellitic acid trioctyl ester, which comprises the following steps:

[0007] S1, high-color-number yellowish trimellitic acid trioctyl ester is added to a reaction kettle, and stirred and heated to 65-75 DEG C;

[0008] S2, hydrogen peroxide solution is slowly added for decolorization reaction, and stirred and heated to 65-75 DEG C, and kept for 1.5 h.

[0009] S3, after the end of the heat preservation, slowly add dilute alkali solution, stirring and heat preservation 0.5h;

[0010] S4, after the completion of the reaction liquid is transferred to the separatory funnel, static stratification 1h, separation of the lower water phase, the upper organic phase is obtained;

[0011] S5, the upper organic phase is removed by vacuum distillation of water and light components, temperature control in 100-130℃;

[0012] S6, after the end of the dehydration, add activated carbon, decoloring resin stirring decolorization, hot filtration, get low color number trioctyl trimellitate product.

[0013] Preferably, the weight ratio of each component in the above reaction liquid is:

[0014] high color number yellow trioctyl trimellitate: 100%

[0015] Hydrogen peroxide: 0.5-2%

[0016] Activated carbon: 0.5-2%

[0017] Decoloring resin: 0.5-1%

[0018] Dilute alkali solution: 0.5-2%.

[0019] Preferably, the concentration of hydrogen peroxide in S2 is 5-15%.

[0020] Preferably, the hydrogen peroxide in S2 is slowly added by peristaltic pump.

[0021] Preferably, the S2 decolorization reaction involves the following chemical reaction equation:

[0022] Q-O-O-Q+H2O2→2Q-OH+O2↑

[0023] Q-OH+H2O2→Q-(COOH)n+H2O.

[0024] Preferably, the dilute alkali solution in S3 is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate.

[0025] Preferably, the solution PH in S3 is adjusted to 6.5-7.5, and the heat preservation temperature is 65-75℃.

[0026] Preferably, the concentration of dilute alkali solution in S3 is 0.5-1%.

[0027] Preferably, the vacuum degree in S5 is controlled at 500-1000Pa.

[0028] Preferably, the removing time in S5 is 0.3-1h.

[0029] The beneficial effects of the present application are:

[0030] The method for reducing the color number of high-color-number yellowish trimellitic acid trioctyl ester can effectively reduce the color number of high-color-number yellowish trimellitic acid trioctyl ester from 140-180 to 60-70, is environment-friendly, turns waste into treasure, improves the utilization rate of resources, and can obtain trimellitic acid trioctyl ester meeting the industry indexes in all aspects; by controlling the concentration of hydrogen peroxide, the degradation of the color-developing groups is promoted while the influence on the trimellitic acid trioctyl ester is avoided, the quality of the low-color-number trimellitic acid trioctyl ester is ensured, the decolorization reaction of hydrogen peroxide and quinone derivatives in the high-color-number yellowish trimellitic acid trioctyl ester is carried out, the conjugated system is oxidatively destroyed, carboxylic acid or hydroxylated products are generated, and thus the color-developing groups are eliminated;

[0031] The present application carries out three times of decolorization on the high-color-number yellowish trimellitic acid trioctyl ester by adopting hydrogen peroxide, activated carbon and decolorization resin, the color number of the trimellitic acid trioctyl ester is effectively reduced while the yellowing is removed, the concentration of hydrogen peroxide is controlled in the decolorization process, the reaction can effectively promote the decomposition of hydrogen peroxide into hydroxyl radicals, the color-developing groups are effectively degraded, the residual hydrogen peroxide is neutralized by adding a dilute alkali solution, the generation of by-products is avoided, the water and light components in the reaction solution are removed under the conditions of negative pressure and 100-130 DEG C, and thus the esterification rate and quality indexes of the low-color-number trimellitic acid trioctyl ester are ensured. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the description of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0033] The method for reducing the color number of high-color-number yellowish trimellitic acid trioctyl ester comprises the following steps:

[0034] S1, 1000g of high-color-number yellowish trimellitic acid trioctyl ester is added into a reaction kettle, and stirring and heating to 65 DEG C are carried out;

[0035] S2, 15g of 10% hydrogen peroxide solution is slowly added by using a peristaltic pump for decolorization reaction, stirring and heating to 70 DEG C are carried out, and 1.5h of heat preservation is carried out;

[0036] S3, after the heat preservation is completed, 8g of 1% dilute alkali solution is slowly added, stirring and heat preservation are carried out for 0.5h;

[0037] S4, after neutralization, the reaction solution was transferred to a separatory funnel, and the lower aqueous phase was separated after standing for 1 h to obtain 986 g of the upper organic phase;

[0038] S5, 986 g of the organic phase was added to the reaction kettle, and the temperature was raised to 120°C. The water and light components in the reaction solution were removed under a negative pressure of 900 Pa at 120°C to obtain 970 g of the reaction solution;

[0039] S6, after dehydration, 1.2 g of activated carbon and 0.6 g of decolorizing resin were added, and the mixture was stirred at 100-130°C for decolorization. The product, 963 g of trioctyl trimellitate, was obtained by hot filtration.

[0040] The present application utilizes the decolorization reaction of the quinone derivative derived from the high color number yellow trioctyl trimellitate and hydrogen peroxide to oxidatively destroy the conjugated system and generate carboxylic acid or hydroxylated products, thereby eliminating the color-forming groups. For general quinones (Q-O-O-Q structure), the oxidative decolorization reaction of hydrogen peroxide can be simplified as:

[0041] Q-O-O-Q + H2O2→ 2Q-OH + O2↑

[0042] Q-OH + H2O2→ Q-(COOH)n + H2O.

[0043] In this example, the comparison of trioctyl trimellitate in three parallel experiments is as follows:

[0044]

[0045] Note: The product gas phase analysis uses the trioctyl trimellitate product detection method.

[0046] In the above table, the trioctyl trimellitate in three parallel experiments is compared with comparison 1 (original high color number trioctyl trimellitate). It is found that the color number in comparison 1 is 160, and the color number of the other three groups of experiments is reduced to 65-70 after the operation of the present application. The color number of the trioctyl trimellitate is effectively reduced, and the ester content, moisture, acid value, and other indicators of the low color number trioctyl trimellitate all meet the industry indicators.

[0047] By controlling the concentration of hydrogen peroxide, excessive oxidation of the ester group of trioctyl trimellitate is avoided, thereby affecting the product quality. The above gas phase analysis shows that the use of 10% hydrogen peroxide solution for decolorization does not significantly affect the content of the product trioctyl trimellitate. And through other experiments, it is found that by controlling the concentration of hydrogen peroxide to be 5-15%, the color number of high color number yellow trioctyl trimellitate can be effectively reduced from 140-180 to low color number 60-70, and the trioctyl trimellitate will not be affected, ensuring the quality of the trioctyl trimellitate.

[0048] The present application carries out three times of decolorization on high color number and yellowish trimellitic acid trioctyl ester by adopting hydrogen peroxide, activated carbon and decolorizing resin, removes yellow and simultaneously efficiently reduces the color number of trimellitic acid trioctyl ester, controls the concentration of hydrogen peroxide in the decolorization process, makes the reaction effectively promote the decomposition of hydrogen peroxide into hydroxyl radicals, efficiently degrades the chromophoric groups, adds dilute alkali solution to neutralize the residual hydrogen peroxide, avoids the generation of by-products, removes water and light components in the reaction liquid under the condition of negative pressure 100-130 DEG C, thereby ensuring the esterification rate and quality index of low color number trimellitic acid trioctyl ester.

[0049] The above only discloses preferred embodiments of the present application, and of course cannot limit the scope of the present application, therefore equivalent changes made according to the claims of the present application still fall within the scope of the present application.

Claims

1. A method of reducing the color number of high color number yellowing isosorbide trioctyl ester, characterized by, The method comprises the following steps: S1, add high color number yellow tri octyl trimellitate into the reaction kettle, and stir to warm up; S2, slowly add hydrogen peroxide solution for decolorization reaction, stir to warm up to 65-75℃, and keep warm for 1.5h; S3, after keeping warm, slowly add dilute alkali solution, stir and keep warm for 0.5h; S4, after neutralization, transfer the reaction liquid to a separatory funnel, stand for 1h, separate the lower water phase, and obtain the upper organic phase; S5, remove water and light components from the upper organic phase by negative pressure rectification, and control the temperature at 100-130℃; S6, after dehydration, add activated carbon and decolorizing resin, stir to decolorize, filter while hot, and obtain low color number tri octyl trimellitate product.

2. The method of reducing the color number of high color number yellowing triphenylate trioctyl ester according to claim 1, characterized in that, The weight ratio of each component in the above reaction liquid is: High color number yellow tri octyl trimellitate: 100% Hydrogen peroxide: 0.5-2% Activated carbon: 0.5-2% Decolorizing resin: 0.5-1% Dilute alkali solution: 0.5-2%.

3. The method of reducing the color number of high color number yellowing triphenylate trioctyl ester according to claim 1, characterized in that, The concentration of hydrogen peroxide in S2 is 5-15%.

4. The method of reducing the color number of high color number yellowing triphenylate trioctyl ester according to claim 1, characterized in that, The hydrogen peroxide in S2 is slowly added by peristaltic pump.

5. The method of reducing the color of high color yellow triisodecyl trimellitate according to claim 1, characterized in that, The chemical reaction equation involved in the decolorization reaction in S2 is: Q-O-O-Q+H2O2→2Q-OH+O2↑ Q-OH+H2O2→Q-(COOH)n+H2O.

6. The method of reducing the color of high color yellow triisodecyl trimellitate according to claim 1, wherein, The dilute alkali solution in S3 is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate.

7. The method of reducing the color of high color yellow triisodecyl trimellitate according to claim 1, wherein The solution PH in S3 is adjusted to 6.5-7.5, and kept warm at 65-75℃.

8. The method of reducing the color of high color yellow triisodecyl trimellitate according to claim 1, characterized in that, The concentration of dilute alkali solution in S3 is 0.5-1%.

9. The method of reducing the color of high color yellow triisodecyl trimellitate according to claim 1, characterized in that, The vacuum degree in S5 is controlled at 500-1000Pa.

10. The method of reducing the color of high color yellow triisodecyl trimellitate according to claim 1, wherein, The removal time in S5 is 0.3-1h.

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