Epoxy resin refining method

Abstract

The invention belongs to the technical field of epoxy resin production, and particularly relates to an epoxy resin refining method. The preparation method comprises the following steps: mixing crude epoxy resin, an organic solvent and water, and sequentially washing and standing for layering to obtain an organic solution of the crude epoxy resin; the organic solution of the crude epoxy resin and a refining reaction reagent are mixed for a refining reaction, a refined reaction solution is obtained, and the refining reaction reagent comprises a catalyst and an inorganic strong alkali aqueous solution; standing and layering the refined reaction liquid to obtain a lower-layer water phase, a middle-layer middle phase and an upper-layer epoxy resin organic solution; and removing the solvent from the upper layer epoxy resin organic solution to obtain the epoxy resin. By reasonably arranging the steps of washing, refining and desolventizing the crude epoxy resin, TOC in the epoxy resin production wastewater can be effectively reduced, the wastewater treatment cost is saved, and cost-saving, consumption-reducing and green production of the epoxy resin is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of epoxy resin production, and particularly relates to a method for refining epoxy resin. Background Art

[0002] At present, in the one-step epoxy resin production process, the crude resin is directly refined by reaction. An organic catalyst needs to be added during the reaction. After the refining reaction, the wastewater containing salt and organic matter dissolved in the resin is the epoxy resin production wastewater. The epoxy resin production wastewater is a high-salt wastewater, and its components can be roughly divided into three categories: volatile organic matter, such as unreacted monomer epichlorohydrin (ECH), solvent benzene, toluene, volatile phenols and other substances; water-soluble organic matter and inorganic salts, such as incompletely reacted raw materials, organic chlorides, by-product sodium chloride, etc.; oligomers, aged resins, reaction by-products, etc.

[0003] Epoxy resin production wastewater has high treatment costs due to its large water volume and relatively high total organic carbon (TOC) concentration, which has become a serious obstacle to the development of epoxy resin. Summary of the invention

[0004] The object of the present invention is to provide a method for refining epoxy resin. The refining method provided by the present invention can reduce the TOC in the wastewater produced by epoxy resin production, save the cost of wastewater treatment, and realize cost-saving and consumption-reducing and green production of epoxy resin.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a method for refining an epoxy resin, comprising the following steps:

[0007] The crude epoxy resin, the organic solvent and water are mixed and washed and allowed to stand for stratification in sequence to obtain an organic solution of the crude epoxy resin;

[0008] The organic solution of the crude epoxy resin and a refining reaction reagent are mixed for refining reaction to obtain a refining reaction liquid, wherein the refining reaction reagent comprises a catalyst and an inorganic strong alkali aqueous solution;

[0009] The refined reaction solution is allowed to stand for stratification to obtain a lower aqueous phase, an intermediate phase, and an upper epoxy resin organic solution;

[0010] The upper epoxy resin organic solution is desolventized to obtain epoxy resin.

[0011] Preferably, after obtaining the lower aqueous phase, the method further comprises: sequentially concentrating and solid-liquid separating the lower aqueous phase to obtain a recovered liquid, and using the recovered liquid as part of the refined reaction reagent.

[0012] Preferably, the organic solvent is toluene, and the mass of the organic solvent accounts for 50-52% of the mass of the crude epoxy resin.

[0013] Preferably, the mass of the water accounts for 70-75% of the mass of the crude epoxy resin.

[0014] Preferably, the washing temperature is 75-80° C. and the insulation time is 10-15 minutes.

[0015] Preferably, the catalyst is PEG 200; the mass of the catalyst is 2300-2500 ppm of the mass of the crude epoxy resin.

[0016] Preferably, the inorganic strong alkali aqueous solution is a sodium hydroxide aqueous solution; the mass percentage of the inorganic strong alkali aqueous solution is 30-32%; the mass of the inorganic strong alkali aqueous solution accounts for 6-7.5% of the mass of the crude epoxy resin.

[0017] Preferably, the temperature of the refining reaction is 88-95° C., and the insulation time is 60-65 min.

[0018] Preferably, the desolvation temperature is 130-140° C., the pressure is 1-2 kPa, and the time is 50-60 min.

[0019] Preferably, the concentration is flash evaporation; the temperature of the flash evaporation is 70-95° C., the pressure is 14-15 kPa, and the time is 5-10 min.

[0020] The present invention provides a method for refining epoxy resin, comprising the following steps: mixing crude epoxy resin, organic solvent and water, washing and standing for stratification in sequence, to obtain an organic solution of crude epoxy resin; mixing the organic solution of crude epoxy resin and a refining reaction reagent for refining reaction, to obtain a refining reaction liquid, wherein the refining reaction reagent comprises a catalyst and an inorganic strong alkali aqueous solution; standing for stratification of the refining reaction liquid, to obtain a lower aqueous phase, an intermediate phase and an upper epoxy resin organic solution; desolventizing the upper epoxy resin organic solution, to obtain epoxy resin. The present invention can effectively reduce the TOC in epoxy resin production wastewater by reasonably setting the steps of washing, refining and desolventizing the crude epoxy resin, saving the cost of wastewater treatment, and realizing cost saving and consumption reduction and green production of epoxy resin. It can be seen from the results of the embodiment that the refining method provided by the present invention can reduce the TOC of epoxy resin production wastewater by 800 to 1000 ppm compared with the traditional refining method, reducing the cost of treating high-salt wastewater, less pollution, environmentally friendly, and reducing the cost of epoxy resin production.

[0021] Furthermore, in the present invention, after obtaining the lower aqueous phase, the process further includes: sequentially concentrating and solid-liquid separating the lower aqueous phase to obtain a recovered liquid, and applying the recovered liquid as part of the refining reaction reagent. The present invention can realize the reuse of the catalyst and the inorganic strong base in the refining reaction process by recovering and applying the lower aqueous phase after the refining reaction, thereby saving costs and reducing consumption in the production of epoxy resin.

[0022] In summary, the epoxy resin refining method provided by the present invention reduces the cost of using the catalyst and reduces the cost of treating high-salt wastewater. The inorganic strong base and catalyst in the refining reaction can be appropriately recovered for secondary use, which greatly reduces the production cost of the epoxy resin. DETAILED DESCRIPTION

[0023] The present invention provides a method for refining an epoxy resin, comprising the following steps:

[0024] The crude epoxy resin, the organic solvent and water are mixed and washed and allowed to stand for stratification in sequence to obtain an organic solution of the crude epoxy resin;

[0025] The organic solution of the crude epoxy resin and a refining reaction reagent are mixed for refining reaction to obtain a refining reaction liquid, wherein the refining reaction reagent comprises a catalyst and an inorganic strong alkali aqueous solution;

[0026] The refined reaction solution is allowed to stand for stratification to obtain a lower aqueous phase, an intermediate phase, and an upper epoxy resin organic solution;

[0027] The upper epoxy resin organic solution is desolventized to obtain epoxy resin.

[0028] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0029] The present invention sequentially washes and decomposes the crude epoxy resin with a mixture of a crude epoxy resin, an organic solvent and water (hereinafter referred to as the first decomposition), to obtain an organic solution of the crude epoxy resin. In a specific embodiment of the present invention, the hydrolysis chlorine of the crude epoxy resin is 19200ppm. The organic solvent is preferably toluene, and the mass of the organic solvent is preferably 50-52% of the mass of the crude epoxy resin, and specifically 50% in the embodiment. The mass of the water is preferably 70-75% of the mass of the crude epoxy resin, and specifically 75% in the embodiment. The washing is carried out under stirring, the washing temperature is preferably 75-80°C, and the insulation time is preferably 10-15min. After the washing is completed, the present invention preferably pours the solution obtained after washing into a separating funnel while hot for the first decomposition. The time of the first decomposition is preferably 10-5min. The first decomposition obtains an organic solution of a high-salt water layer, an intermediate layer and a crude epoxy resin.

[0030] After obtaining the organic solution of the crude epoxy resin, the present invention mixes the organic solution of the crude epoxy resin with a refining reaction reagent for refining reaction to obtain a refining reaction liquid, wherein the refining reaction reagent includes a catalyst and an inorganic strong alkali aqueous solution. In the present invention, the catalyst is preferably PEG 200. The mass of the catalyst is preferably 2300 to 2500 ppm of the mass of the crude epoxy resin, and specifically 2500 ppm in the embodiment. The inorganic strong alkali aqueous solution is preferably a sodium hydroxide aqueous solution. The mass percentage of the inorganic strong alkali aqueous solution is preferably 30 to 32%. The mass of the inorganic strong alkali aqueous solution as a percentage of the mass of the crude epoxy resin is preferably 6 to 7.5%, and specifically 6.6% or 7.5% in the embodiment.

[0031] In the present invention, when the refining reaction reagent is not used for recycling, the mixing of the organic solution of the crude epoxy resin and the refining reaction reagent includes the following steps: heating the organic solution of the crude epoxy resin to the temperature of the refining reaction and stirring and mixing with the catalyst to obtain a mixed solution; adding the inorganic strong alkali aqueous solution to the mixed solution under stirring. The dropping speed is preferably 7 to 12 g / min. The temperature of the refining reaction is preferably 88 to 95°C, specifically 90°C or 92°C in the embodiment; the insulation time of the refining reaction is preferably 60 to 65 minutes. The insulation time of the refining reaction is calculated from the completion of the dropwise addition.

[0032] After obtaining the refined reaction liquid, the present invention allows the refined reaction liquid to stand for stratification (hereinafter referred to as the second standing stratification) to obtain a lower aqueous phase, an intermediate intermediate phase, and an upper epoxy resin organic solution. In the present invention, the second standing stratification is preferably performed in a separating funnel. The time for the second standing stratification is preferably 10 to 15 minutes.

[0033] After obtaining the upper epoxy resin organic solution, the present invention removes the solvent from the upper epoxy resin organic solution to obtain epoxy resin. In the present invention, the temperature of the desolvation is preferably 130 to 140° C., the pressure is preferably 1 to 2 kPa, and the time is preferably 50 to 60 minutes. The desolvation is carried out under stirring.

[0034] In the present invention, after obtaining the lower aqueous phase, the present invention preferably further comprises: sequentially concentrating and solid-liquid separating the lower aqueous phase to obtain a recovered liquid, and applying the recovered liquid as part of the refined reaction reagent. In the present invention, the concentration is preferably flash evaporation; the temperature of the flash evaporation is preferably 70 to 95°C, the pressure is preferably 14 to 15 kPa, and the time is preferably 5 to 10 min. The solid-liquid separation is preferably filtration. The present invention preferably recovers part of the water in the lower aqueous phase by concentration. The present invention removes part of the salt and insoluble impurities in the concentrated liquid obtained by the concentration by the solid-liquid separation. After obtaining the recovered liquid, the present invention preferably detects the catalyst concentration and the inorganic strong base concentration in the recovered liquid.

[0035] In the present invention, when the recovery liquid is used as part of the purified reaction reagent, the recovery liquid is used as a catalyst for the purified reaction reagent and part of the inorganic strong alkali aqueous solution.

[0036] In the present invention, when the recovered liquid is used as part of the refined reaction reagent, the specific method of using preferably includes: mixing the organic solution of the crude epoxy resin, the recovered liquid and the additional inorganic strong alkali aqueous solution for refining reaction. The mass percentage of the catalyst in the recovered liquid is preferably 18%. The mass percentage of the inorganic strong alkali in the recovered liquid is preferably 22%. The mass ratio of the recovered liquid to the additional inorganic strong alkali aqueous solution is preferably 8.2:38.

[0037] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0038] The crude resin used in the following examples and comparative examples is the same batch of crude epoxy resin. The hydrolyzed chlorine content of the crude epoxy resin is 19200 ppm. The hydrolyzed chlorine content of the finished epoxy resin is qualified if it is ≤300 ppm.

[0039] Comparative Example 1

[0040] The method for refining the crude epoxy resin provided in this comparative example specifically comprises the following steps:

[0041] Take 600g crude resin and 300g toluene and place them in a 2000mL reaction bottle, start stirring and heat to 92°C, add 1.5g catalyst (PEG 200), drip 39.5g of 32% sodium hydroxide aqueous solution, drip for 5min, keep warm for 60min after the dripping, add 450g of clean water and stir for 10min after the insulation. After the end, pour it into a separatory funnel and let it stand for 10min to separate the high salt water, the middle phase and the resin toluene solution. The resin toluene solution is placed in a 2000mL reaction bottle, 250g toluene, 200g clean water and 0.5g sodium dihydrogen phosphate are added, stirred, heated to 80°C, and kept warm for 15min. After the insulation is completed, pour it into a separatory funnel while hot and let it stand for 10min to separate the low salt water, the middle phase and the resin toluene solution. The resin toluene solution was placed in a 1000mL desolventizing bottle, stirred, heated to 140°C, the desolventizing pressure was 1kPa, the desolventizing time was 60min, and the epoxy resin product was taken after the desolventizing was completed. The TOC test result of the high-salt wastewater (i.e. the high-salt water separated above) was 2980ppm, and the quality of the epoxy resin product was qualified (hydrolyzed chlorine was 223ppm).

[0042] Example 1

[0043] Take 800g crude resin, 600g water and 400g toluene and place them in a 2000mL reaction bottle, start stirring, heat to 80℃ and keep warm for 15min. After the insulation is completed, pour it into a separatory funnel while hot and let it stand for 10min to separate the high brine, the middle phase and the crude resin toluene solution. Take the crude resin toluene solution and place it in a 2000mL reaction bottle, start stirring and heat it to 90℃, add 2g of catalyst (PEG 200), drip 53g of 32% sodium hydroxide aqueous solution, the dripping time is 5min, and the dripping is completed. After the reaction is completed, pour it into a separatory funnel and let it stand for 10min to separate the recovered liquid, the middle phase and the resin toluene solution. The resin toluene solution is placed in a 1000mL desolventizing bottle, stirred, heated to 140℃, the desolventizing pressure is 1kPa, the desolventizing time is 60min, and the desolventizing is completed to take the epoxy resin finished product. The recovered liquid was placed in a 500mL desolventizing bottle, stirred, heated to 70°C, and stopped heating after the pressure was turned on (15kPa), flashed for 5 minutes, and the remaining recovered liquid was filtered after the flashing was completed. The TOC test result of the high-salt wastewater (i.e. the high-salt water separated above) was 2100ppm (880ppm lower than the traditional process), and the quality of the finished epoxy resin was qualified (hydrolyzed chlorine was 183ppm).

[0044] Example 2

[0045] Take 600g crude resin, 450g water and 300g toluene and place them in a 2000mL reaction bottle, start stirring, heat to 80℃ and keep warm for 15min. After the insulation is completed, pour it into a separatory funnel while hot and let it stand for 10min to separate the high brine, the middle phase and the crude resin toluene solution. Take the crude resin toluene solution and place it in a 2000mL reaction bottle, start stirring and heat it to 92℃, add 1.5g of catalyst (PEG 200), drip 39.5g of 32% sodium hydroxide aqueous solution, the dripping time is 5min, and the dripping is completed and kept warm for 60min. After the reaction is completed, pour it into a separatory funnel and let it stand for 10min to separate the recovered liquid, the middle phase and the resin toluene solution. The resin toluene solution is placed in a 1000mL desolventizing bottle, stirred, heated to 140℃, the desolventizing pressure is 1kPa, the desolventizing time is 60min, and the desolventizing is completed to take the epoxy resin finished product. The recovered liquid was placed in a 500mL desolventizing bottle, stirred, heated to 70°C, and stopped heating after the pressure was turned on (15kPa), flashed for 5 minutes, and the remaining recovered liquid was filtered after the flashing was completed. The TOC test result of the high-salt wastewater was 1950ppm (1030ppm lower than the traditional process), and the quality of the epoxy resin finished product was qualified (hydrolyzed chlorine was 212ppm).

[0046] Example 3

[0047] Take 600g crude resin, 450g water and 300g toluene and place them in a 2000mL reaction bottle, start stirring, heat to 80℃ and keep warm for 15min. After the insulation is completed, pour it into a separatory funnel while hot and let it stand for 10min to separate the high brine, the middle phase and the crude resin toluene solution. Take the crude resin toluene solution and place it in a 2000mL reaction bottle, start stirring and heat it to 92℃, add 8.2g of recovery liquid (1.48g of catalyst, 1.8g of sodium hydroxide), add 38g of sodium hydroxide aqueous solution, add for 5min, and keep warm for 60min after the addition. After the reaction is completed, pour it into a separatory funnel and let it stand for 10min to separate the recovery liquid, the middle phase and the resin toluene solution. The resin toluene solution is placed in a 1000mL desolventizing bottle, stirred, heated to 140℃, the desolventizing pressure is 1kPa, the desolventizing time is 60min, and the epoxy resin product is taken after the desolventizing. The recovered liquid was placed in a 500mL desolventizing bottle, stirred, heated to 70°C, and stopped heating after the pressure was turned on (15kPa), flashed for 5 minutes, and the remaining recovered liquid was filtered after the flashing was completed. The TOC test result of the high-salt wastewater was 2010ppm (970ppm lower than the traditional process), and the quality of the epoxy resin finished product was qualified (hydrolyzed chlorine was 287ppm).

[0048] The data of the high brine and epoxy resin products produced in Examples 1 to 3 and Comparative Example 1 are shown in Table 1.

[0049] Table 1 Data of high brine and epoxy resin products produced in Examples 1 to 3 and Comparative Example 1

[0050] Serial number Reaction process type Catalyst type High salt water TOC / ppm Epoxy resin hydrolysis chlorine / ppm Comparative Example 1 Traditional production methods new 2980 223 Example 1 Production method of the present invention new 2100 183 Example 2 Production method of the present invention new 1950 212 Example 3 Production method of the present invention Recycle 2010 287

[0051] It can be seen from the above embodiments that, compared with the prior art, the characteristics and beneficial effects of the present invention are:

[0052] By reasonably arranging the steps of washing and refining reaction, the present invention can reduce the TOC of high-salt wastewater by 800-1000ppm compared with the traditional refining process (Comparative Example 1), and the catalyst can be recycled and reused, with less pollution and environmental friendliness. The cost of using the catalyst is reduced while the cost of treating the high-salt wastewater is reduced. The sodium hydroxide in the refining reaction can also be appropriately recycled for secondary use, which greatly reduces the production cost of the epoxy resin.

[0053] It can be seen from this that the epoxy resin refining method provided by the present invention can not only reduce the TOC in high-salt wastewater and save wastewater treatment costs, but also enable the recovered catalyst and sodium hydroxide to be reused, providing a new direction for enterprises to save costs and reduce consumption and achieve green development.

[0054] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for refining epoxy resin, characterized in that: The following steps are involved: The crude epoxy resin, the organic solvent and water are mixed and washed and allowed to stand for stratification in sequence to obtain an organic solution of the crude epoxy resin; The organic solution of the crude epoxy resin and a refining reaction reagent are mixed for refining reaction to obtain a refining reaction liquid, wherein the refining reaction reagent comprises a catalyst and an inorganic strong alkali aqueous solution; The refined reaction solution is allowed to stand for separation to obtain a lower aqueous phase, a middle intermediate phase and an upper epoxy resin organic solution; The upper epoxy resin organic solution is desolventized to obtain epoxy resin.

2. The epoxy resin refining method according to claim 1, characterized in that: After obtaining the lower aqueous phase, the method further comprises: sequentially concentrating and solid-liquid separating the lower aqueous phase to obtain a recovered liquid, and using the recovered liquid as part of the refined reaction reagent.

3. The epoxy resin refining method according to claim 1, characterized in that: The organic solvent is toluene, and the mass of the organic solvent accounts for 50-52% of the mass of the crude epoxy resin.

4. The epoxy resin refining method according to claim 1, characterized in that: The mass of the water accounts for 70-75% of the mass of the crude epoxy resin.

5. The method for refining epoxy resin according to claim 1, 3 or 4, characterized in that: The washing temperature is 75-80° C. and the heat preservation time is 10-15 minutes.

6. The epoxy resin purification method according to claim 1, characterized in that: The catalyst is PEG 200; the mass of the catalyst is 2300-2500 ppm of the mass of the crude epoxy resin.

7. The method for refining epoxy resin according to claim 1, characterized in that: The inorganic strong alkali aqueous solution is a sodium hydroxide aqueous solution; the mass percentage of the inorganic strong alkali aqueous solution is 30-32%; the mass of the inorganic strong alkali aqueous solution accounts for 6-7.5% of the mass of the crude epoxy resin.

8. The method for refining epoxy resin according to claim 1, 6 or 7, characterized in that: The temperature of the refining reaction is 88-95° C., and the insulation time is 60-65 minutes.

9. The method for refining epoxy resin according to claim 1 or 3, characterized in that: The desolventizing process is carried out at a temperature of 130 to 140° C., a pressure of 1 to 2 kPa, and a time of 50 to 60 minutes.

10. The method for refining epoxy resin according to claim 2, characterized in that: The concentration is flash evaporation; the temperature of the flash evaporation is 70-95°C, the pressure is 14-15 kPa, and the time is 5-10 minutes.