CN102381973A - Production process of ultra-high purity (electronic grade) lactate product - Google Patents

Abstract

A production process of electronic-grade lactate products, which is composed of a flash system-lightening rectification system and a semi-finished product rectification system-activated carbon decolorization system-ion exchange system. The whole recovery rate of lactate is greater than 98%. The purity of lactate is as high as 99.9999%, the metal ion content is less than 3ppb, and it is colorless. Fully meet the high requirements of the electronics industry. The light components in the process of the invention are returned to the flash evaporator for reprocessing, and the heavy components in the second tower are treated centrally, which greatly improves the yield of finished products, reduces the discharge of residues, and improves the economy and treatment cost of the process.

Description

A kind of production technology of ultra-high purity (electronic grade) lactate products

technical field

The invention relates to a production process of ultra-high-purity (electronic grade) lactate products.

Background technique

Lactic acid esters mainly refer to methyl lactate, ethyl lactate and butyl lactate, which are the products of lactic acid produced by fermentation of lactose, starch and other sugars with methanol, ethanol and butanol respectively. Lactic acid esters are a class of biodegradable and non-toxic solvents, which are very capable of replacing some traditional solvents because they have many excellent physical and chemical properties, such as: (1) for resins (nitrocellulose, acrylic resins, polyesters, etc.) Urethane, polyester, alkyd resin, epoxy resin, etc.) have excellent solubility; (2) Relatively high solubility in water and good solubility in most organic solvents; (3) Relatively high solubility in water Low volatility makes it effective for surface treatment; (4) Relatively high boiling point makes it effective for high temperature environments. Lactic acid esters can be used alone or as a cleaning solvent formulation for cleaning various precision machinery and cleaning before surface coating. As a cleaning agent, lactic acid ester has the advantages of low loss during use, good economy, no adverse effect on the object to be cleaned, non-toxic, and easy biodegradation. It is a new alternative to ODS (Ozone Depleting Substances) solvent-based cleaning agents. agent. It is widely used in the electronics industry, and can be used to clean various optical discs, liquid crystal displays, magnetic heads, chips, circuit board substrates, and modules; it can also be used to clean optical lenses, printing screens, inks, and metals.

At present, domestic lactic acid esters can only be used as additives in food and other industries. The lactic acid by-products present in lactic acid esters are difficult to separate from the lactic acid esters, and the color of the lactic acid esters obtained by distillation cannot meet the requirements for use. Other impurities such as pyruvate are also difficult to separate by ordinary distillation and difficult to resolve by activated carbon. Lactate esters will be contaminated by metal ions and non-metal ions during the preparation process. According to different preparation methods, the maximum can reach 500pm. However, electronic-grade lactic acid esters require unique high purity (more than 99.5% by mass) and extremely low metal content (below 10ppb) to meet the high-quality requirements of the semiconductor industry. Therefore, in practical applications, it is very important to produce high-quality and stable lactate products.

In view of this, it is necessary to develop a new technology for ultra-high purification of lactic acid esters.

Contents of the invention

The object of the present invention is to provide a new technology for purifying lactate products, i.e. methyl lactate, ethyl lactate and butyl lactate, to obtain its ultra-high-purity electronic grade lactate product, with a purity higher than 99.9999%. The content of metal ions is less than 3ppb, which can provide high-quality solvents and cleaning agents for the semiconductor industry.

In order to achieve the above object, the technical scheme of the present invention is as follows:

A production process for electronic-grade lactate products, which is composed of a flash evaporation system-light removal and semi-finished product rectification system-activated carbon decolorization system-ion exchange system. The process is shown in Figure 1, which includes the following steps:

(1) Add food-grade lactic acid esters with a purity of more than 99.0% containing complex impurity components into the flash evaporator, and through decompression flash operation, part of the water and low boiling substances such as alcohols contained in the raw materials will be converted into gaseous Evaporated from the top of the flash evaporator, condensed by the top condenser and discharged, the liquid phase material in the flash evaporator is discharged from the bottom of the flash evaporator, and sent to the light removal tower for further distillation and separation. The operating pressure of the flash evaporator is controlled at 5~100KPa , preferably 10~60KPa; the operating temperature is 68~142°C, preferably 80~130°C;

The lactate crude product described in the process of the present invention is operated through a flash evaporator, and the purpose is to remove 15% to 65% of the moisture and alcohols and other low boilers contained in the lactate crude product, and to remove moisture and alcohols 20~45% of the total amount of low boilers is excellent. This not only reduces the processing load of the light removal tower, reduces the equipment investment of the light removal tower and its accessories, but also greatly reduces the energy consumption of the whole process;

(2) The lactic acid ester after decompression flashing enters the light removal tower. In the light removal tower, almost all the remaining water and alcohol and other low boilers in the material are removed and distilled from the top of the tower. Because it contains Lactate, so it will be sent to the flash evaporator for recycling and separation again, while the material discharged from the bottom of the light removal tower will be sent to the refining tower for further refining;

The above-mentioned light removal tower is generally a packed tower, or a combined tower of a packed tower and a plate tower. The material is mainly stainless steel. In special cases, ceramics, tetrafluoroethylene, etc. can also be used. The number of theoretical plates is 20 to 200, preferably 30. ~120 blocks, the operating pressure at the top of the light removal tower is 5~60KPa, preferably 10~40KPa; the operating temperature is 34~102°C, preferably 50~90°C; the reflux ratio of the light removal tower is 10~100, Preferably 13~55;

(3) The material discharged from the bottom of the light removal tower is rectified in the refining tower, and the remaining traces of water, alcohol and other light components in the material are extracted from the top of the tower, and the super high Pure lactate semi-finished products (its purity is above 99.99992%). The ultra-high-purity lactate semi-finished product is sent to the activated carbon decolorization system for further processing;

What is extracted from the bottom of the refining tower is a small amount of lactic acid ester and lactic acid, as well as all concentrated high boilers, solids, mechanical impurities and other impurities that have not been removed by vaporization brought in by the crude lactic acid ester product. It will be discharged from the tower kettle and sent to the residual liquid storage tank for storage and centralized treatment;

The said refining tower is generally also a packed tower, or a combined tower of a packed tower and a plate tower, and the material is mainly stainless steel. In special cases, ceramics, tetrafluoroethylene, etc. can also be used. The number of theoretical plates is 30 to 200, preferably 40~150 blocks, the operating pressure at the top of the refining tower is 5~60KPa, preferably 10~40KPa; the operating temperature is 70~137°C, preferably 80~120°C; the reflux ratio of the refining tower is 0.05~3.0, Preferably 0.3~1.5;

When the ultra-high-purity lactate semi-product is extracted from the upper side line of the refining tower, the extraction method can be either vapor phase or liquid phase, and the liquid phase extraction is the best, and the theoretical plate number from the extraction position to the top of the tower is 5~ 20 pieces, preferably 6~15 pieces;

(4) The ultra-high-purity lactic acid ester semi-finished product extracted from the upper side of the refining tower enters the activated carbon decolorization system to remove pigment impurities or other impurity components, so that the color of the product meets the requirements. The activated carbon used is preferably coconut shell activated carbon, or other activated carbon with a specific surface area equivalent to 1000-3000m ² /g;

(5) After decolorization, the ultra-high-purity lactate semi-finished product enters the ion exchange system to remove cations (metal ions, etc.) and anions (chloride ions, etc.), or other neutral impurities containing metal ions. In the exchange system, the metal ions, chloride ions and other neutral impurities containing metal ions in the material are basically removed. The ion exchange system is a system composed of cations, anions and non-anion and non-cation exchange columns; the described The three ion exchange columns are filled with Amberlite IR120 Na type cation exchange resin, Amberlite IRA402 Cl type anion exchange resin and Amberlite ^TM XAD4 type macroporous adsorption resin or other ion exchange resins and adsorption resins with equivalent performance. The lactate product output by the system is a colorless electronic grade lactate product with a purity higher than 99.9999%, a metal ion content of less than 3ppb.

In the above-mentioned production process, the raw material storage tanks and product storage tanks in the production process need to be filled with nitrogen for protection. All equipment is well sealed and must not leak air during negative pressure operation. It must be pickled, alkali washed, washed with high-purity water (water to remove anions and cations), and then dried by clean hot air before use.

The above-mentioned production process requires a dust-free workshop, which is designed and certified by GMP; the finished product is sealed and stored by dust-free filling.

The production process and device of the electronic grade lactic acid ester products of the present invention use food-grade lactic acid esters with a purity of more than 99.0% or other grades of equivalent purity as raw materials to obtain a product with a purity higher than 99.9999% and a metal ion content lower than 3ppb. And colorless (≤5 color scale) electronic grade lactate.

The present invention is characterized in that it adopts integrated technologies such as flash evaporation-two-tower rectification-activated carbon decolorization-ion exchange and dust-free filling and storage to produce ultra-high purity (such as electronic grade) lactic acid ester products. The whole recovery rate of lactate is greater than 98%. The purity of lactate is as high as 99.9999%, the metal ion content is less than 3ppb, and it is colorless. Fully meet the high requirements of the electronics industry. The light components in the process of the invention are returned to the flash evaporator for reprocessing, and the heavy components in the second tower are treated centrally, which greatly improves the yield of finished products, reduces the discharge of residues, and improves the economy and treatment cost of the process.

Description of drawings

Fig. 1 is the production process schematic diagram of a kind of electronic grade lactic acid ester product of the present invention, wherein: 1-flash evaporator; , 7- collecting tank; 8, 9, 10- condenser; 12, 15- tower bottom reboiler; 14- high-purity lactate semi-finished product extraction outlet; 16- residue outlet; 17- decolorization column; 18- cation exchange Column; 19-anion exchange column; 20-non-anion and non-cation exchange column; 21-ultra-high purity lactate product export.

Detailed ways

The present invention is described in detail by the following examples, but it should not be understood as a limitation to the scope of patent protection of the present invention.

Example 1

(1) Send the crude methyl lactate into the flash evaporator at a rate of 150kg/h, which contains 4200 mg/kg of methanol, 3060 mg/kg of water, 1290 mg/kg of lactic acid, and a mass content of 99.1% of methyl lactate , the content of metal ions and heavy component impurities is 450 mg/kg. The operating pressure of the flasher is 10KPa, and the operating temperature is about 84°C. In the flash evaporator, about 65% of the water and methanol and other low boilers in the crude methyl lactate are removed. The solution at the bottom of the flash evaporator is pumped into the middle of the light removal tower at a flow rate of 118.95kg/h. The light removal tower is equipped with SS304 stainless steel wire mesh structured packing, the number of theoretical plates is 92, the inner diameter of the tower is 0.13m, the operating pressure at the top of the tower is 10KPa, and the temperature is about 46°C. Low boilers such as water and methanol are distilled from the top of the tower, and the reflux ratio is 25.0. Methyl lactate, heavy components, etc. are discharged from the tank of the light removal tower at a flow rate of 118.45kg/h, and are pumped to the feed port of the refining tower.

(2) The internal parts of the refining tower adopt SS316L stainless steel wire mesh structured packing, the number of theoretical plates is 135, the inner diameter of the tower is 0.30m, the operating pressure at the top of the tower is 10KPa, and the temperature is 87°C. Methyl lactate containing a small amount of water and low boilers such as methanol is extracted from the top of the refining tower, which is sent to the flash evaporator for recycling and separation, and the operating reflux ratio is 3.0. Ultra-high purity methyl lactate (mass content 99.999956%) is extracted from the side line liquid phase at the upper part of the tower at a flow rate of 118.02kg/h (the theoretical plate number from the extraction outlet to the top of the tower is 16), and then sent to the activated carbon decolorization system discoloration. The activated carbon decolorization system is a fixed bed decolorization column with a column height of 2 meters, an activated carbon filling height of 1.6 meters, and a diameter of 0.5 meters. Activated carbon is coconut shell activated carbon with a specific surface area of 2800m ² /g. After decolorization, the material is a colorless liquid (≤5 color scale).

After that, the material is sent to the ion exchange system, and after being treated with anion, cation, non-anion and non-cation exchange resins respectively, more than 99.999981% of electronic grade methyl lactate products can be obtained (wherein the water content is less than 3.5mg/kg, methanol The content is less than 1.4mg/kg, the lactic acid content is less than 7.6 mg/kg, and the metal ion content is less than 2.5μg/kg). Anion, cation, and non-anion and non-cation exchange columns have a column height of 2 meters and a diameter of 0.53 meters. The resins filled respectively are Amberlite IR120 Na type cation exchange resin, Amberlite IRA402 Cl type anion exchange resin and Amberlite ^TM XAD4 type macropore Absorbent resin.

The still residual liquid is discharged from the tower kettle at a flow rate of 0.43kg/h, and is sent to the residual liquid storage tank to be accumulated to a certain amount before centralized treatment.

Qualified products are sent to product storage tanks with nitrogen seals, and are shipped out after dust-free filling and sealing by automatic filling machines.

Example 2

(1) Send the crude ethyl lactate into the flash evaporator at a rate of 100kg/h, which contains 3070mg/kg of ethanol, 2130mg/kg of water, 1420mg/kg of lactic acid, 99.3% of the mass content of ethyl lactate, and metal ions And the heavy component impurity content is 380mg/kg. The operating pressure of the flasher is 5KPa, and the operating temperature is about 68°C. About 15% of water and low boiling substances such as ethanol in the crude ethyl lactate can be removed. The solution at the bottom of the flash evaporator is pumped into the middle of the light removal tower at a flow rate of 91.41kg/h. SS304 stainless steel wire mesh structured packing is installed in the light removal tower, the number of theoretical plates is 20, the inner diameter of the tower is 0.1m, the operating pressure at the top of the tower is 5KPa, and the temperature is about 34°C. Low boilers such as water and ethanol are distilled from the top of the tower, and the reflux ratio is 75.0. Ethyl lactate and heavy components are discharged from the tank of the light removal tower at a flow rate of 90.91kg/h, and are pumped to the feed port of the refining tower.

(2) The internal parts of the refining tower adopt SS316L stainless steel wire mesh structured packing, the number of theoretical plates is 30, the inner diameter of the tower is 0.26m, the operating pressure at the top of the tower is 5KPa, and the temperature is 70°C. Ethyl lactate containing a small amount of water and low boilers such as ethanol is extracted from the top of the refining tower, which is sent to the flash evaporator for recycling and separation, and the operating reflux ratio is 0.8. Ultra-high purity ethyl lactate (mass content 99.99994%) is extracted from the side line liquid phase at the upper part of the tower at a flow rate of 90.40kg/h (the theoretical plate number from the extraction outlet to the top of the tower is 5), and then sent to the activated carbon decolorization system discoloration. The activated carbon decolorization system is a fixed bed decolorization column with a column height of 2 meters, an activated carbon filling height of 1.6 meters, and a diameter of 0.41 meters. Activated carbon is coconut shell activated carbon with a specific surface area of 2800m ² /g. After decolorization, the material is a colorless liquid (≤5 color scale).

After that, the material is sent to the ion exchange system, and after being treated with anion, cation, and non-anion and non-cation exchange resins, more than 99.999950% of electronic grade ethyl lactate products can be obtained (wherein the water content is less than 30.3mg/kg, ethanol The content is less than 10.1 mg/kg, the lactic acid content is less than 5.1 mg/kg, and the metal ion content is less than 2.7 μg/kg). Anion, cation, and non-anion and non-cation exchange columns have a column height of 2 meters and a diameter of 0.43 meters. The resins filled are Amberlite IR120 Na type cation exchange resin, Amberlite IRA402 Cl type anion exchange resin and Amberlite ^TM XAD4 type macropore Absorbent resin.

The still residual liquid is discharged from the tower kettle at a flow rate of 0.51kg/h, and is sent to the residual liquid storage tank to be accumulated to a certain amount before centralized treatment.

Qualified products are sent to product storage tanks with nitrogen seals, and are shipped out after dust-free filling and sealing by automatic filling machines.

Example 3

(1) Send the crude methyl lactate into the flash evaporator at a rate of 1500kg/h, which contains 2620 mg/kg of methanol, 3170 mg/kg of water, 2760 mg/kg of lactic acid, and a mass content of 99.1% of methyl lactate , the content of metal ions and heavy component impurities is 450 mg/kg. The operating pressure of the flasher is 100KPa, and the operating temperature is about 142°C. About 33% of water and low boiling substances such as methanol in the crude methyl lactate can be removed. The solution at the bottom of the flash evaporator is pumped into the middle of the light removal tower at a flow rate of 1376.33kg/h. The light removal tower is equipped with SS304 stainless steel wire mesh structured packing, the number of theoretical plates is 90, the inner diameter of the tower is 0.37m, the operating pressure at the top of the tower is 10KPa, and the temperature is 47°C. Low boilers such as water and methanol are distilled from the top of the tower, and the reflux ratio is 55.0. Methyl lactate and heavy components are discharged from the tank of the light removal tower at a flow rate of 1366.33 kg/h, and are pumped to the feed port of the refining tower.

(2) The internal parts of the refining tower adopt SS316L stainless steel wire mesh structured packing, the number of theoretical plates is 160, the inner diameter of the tower is 0.82m, the operating pressure at the top of the tower is 10KPa, and the temperature is 87°C. Methyl lactate containing a small amount of water and low boilers such as methanol is extracted from the top of the refining tower, which is sent to the flasher for recycling and separation, and the operating reflux ratio is 0.05. Ultra-high purity ethyl lactate (mass content 99.999937%) is extracted from the side line liquid phase at the upper part of the tower at a flow rate of 1360.21kg/h (the number of theoretical plates from the extraction outlet to the top of the tower is 12), and then sent to the activated carbon decolorization system discoloration. The activated carbon decolorization system is a fixed bed decolorization column with a column height of 4 meters, an activated carbon filling height of 3.2 meters, and a diameter of 1.5 meters. Activated carbon is coconut shell activated carbon with a specific surface area of 2800m ² /g. After decolorization, the material is a colorless liquid (≤5 color scale).

Afterwards, the material is sent to the ion exchange system, and after being treated with anion, cation, and non-anion and non-cation exchange resins respectively, an electronic grade ethyl lactate product of more than 99.999943% can be obtained (wherein the water content is less than 31mg/kg, and the ethanol content less than 10 mg/kg, lactic acid less than 16 mg/kg, metal ion less than 1.9 μg/kg). Anion, cation, non-anion and non-cation exchange columns have a column height of 4 meters and a diameter of 1.5 meters. The resins filled are Amberlite IR120 Na type cation exchange resin, Amberlite IRA402 Cl type anion exchange resin and Amberlite ^TM XAD4 type macropore Absorbent resin.

The still residual liquid is discharged from the tower kettle at a flow rate of 6.12kg/h, and is sent to the residual liquid storage tank to be accumulated to a certain amount before centralized treatment.

Qualified products are sent to product storage tanks with nitrogen seals, and are shipped out after dust-free filling and sealing by automatic filling machines.

Example 4

(1) Send the crude butyl lactate into the flash evaporator at a rate of 1500kg/h, which contains 3120 mg/kg of butanol, 1880 mg/kg of water, 2510 mg/kg of lactic acid, and a mass content of 99.1% of butyl lactate %, the impurity content of metal ions and heavy components is 1490 mg/kg. The operating pressure of the flasher is 23.5KPa, and the operating temperature is about 108°C. About 30% of the water and low boiling substances such as butanol in the crude butyl lactate can be removed. The solution at the bottom of the flash evaporator is pumped into the middle of the light removal tower at a flow rate of 1372.74kg/h. The light removal tower is equipped with SS304 stainless steel wire mesh structured packing, the number of theoretical plates is 200, the inner diameter of the tower is 0.53m, the operating pressure at the top of the tower is 24KPa, and the temperature is about 69°C. Low boilers such as water and butanol are distilled from the top of the tower, and the reflux ratio is 100.0. Butyl lactate and heavy components are discharged from the tank of the light removal tower at a flow rate of 1356.74kg/h, and are pumped to the feed port of the refining tower.

(2) The internal parts of the refining tower adopt SS316L stainless steel wire mesh structured packing, the number of theoretical plates is 200, the inner diameter of the tower is 0.81m, the operating pressure at the top of the tower is 25KPa, and the temperature is 111°C. The top of the refining tower produces butyl lactate containing a small amount of water and low boilers such as butanol, which is sent to the flash evaporator for recycling and separation, and the operating reflux ratio is 0.5.

Ultra-high purity butyl lactate (mass content 99.999926%) is extracted from the upper side line liquid phase of the tower at a flow rate of 1350.1kg/h (theoretical plate number from the extraction outlet to the top of the tower is 20), and then sent to the activated carbon decolorization system discoloration. The activated carbon decolorization system is a fixed bed decolorization column with a column height of 4 meters, an activated carbon filling height of 3.2 meters, and a diameter of 1.5 meters. Activated carbon is coconut shell activated carbon with a specific surface area of 2800m ² /g. After decolorization, the material is a colorless liquid (≤5 color scale).

After that, the material is sent to the ion exchange system, and after being treated with anion, cation, and non-anion and non-cation exchange resins, more than 99.999941% of electronic-grade butyl lactate products can be obtained (wherein the water content is less than 1mg/kg, butanol The content is less than 53.7 mg/kg, the lactic acid content is less than 3 mg/kg, and the metal ion content is less than 2.3 μg/kg). Anion, cation, non-anion and non-cation exchange columns have a column height of 4 meters and a diameter of 1.5 meters. The resins filled are Amberlite IR120 Na type cation exchange resin, Amberlite IRA402 Cl type anion exchange resin and Amberlite ^TM XAD4 type macropore Absorbent resin.

The still residual liquid is discharged from the tower kettle at a flow rate of 6.74kg/h, and is sent to the residual liquid storage tank for centralized treatment after accumulating to a certain amount.

Qualified products are sent to product storage tanks with nitrogen seals, and are shipped out after dust-free filling and sealing by automatic filling machines.

Example 5

(1) Send the crude butyl lactate into the flash evaporator at a rate of 150kg/h, which contains 2970mg/kg of butanol, 2870mg/kg of water, 3470mg/kg of lactic acid, 99.0% of the mass content of butyl lactate, metal The impurity content of ions and heavy components is 430mg/kg. The operating pressure of the flasher is 24KPa, and the operating temperature is about 108°C. About 31% of water and low boiling substances such as butanol in the crude butyl lactate can be removed. The solution at the bottom of the flash evaporator is pumped into the middle of the light removal tower at a flow rate of 136.14kg/h. SS304 stainless steel wire mesh structured packing is installed in the light removal tower, the number of theoretical plates is 150, the inner diameter of the tower is 0.15m, the operating pressure at the top of the tower is 25KPa, and the temperature is 111°C. Low boilers such as water and butanol are distilled from the top of the tower, and the reflux ratio is 50.0. Butyl lactate and heavy components are discharged from the tank of the light removal tower at a flow rate of 135.15kg/h, and are pumped to the feed port of the refining tower.

(2) The internal parts of the refining tower adopt SS316L stainless steel wire mesh structured packing, the number of theoretical plates is 120, the inner diameter of the tower is 0.26m, the operating pressure at the top of the tower is 25KPa, and the temperature is 111°C. The top of the refining tower produces ethyl lactate containing a small amount of water and low boilers such as butanol, which is sent to the flasher for recycling and separation, and the operating reflux ratio is 0.5. Ultra-high purity butyl lactate (mass content 99.999946%) is extracted from the side line liquid phase at the upper part of the tower at a flow rate of 134.12kg/h (the number of theoretical plates from the extraction outlet to the top of the tower is 12), and then sent to the activated carbon decolorization system discoloration. The activated carbon decolorization system is a fixed bed decolorization column with a column height of 2 meters, an activated carbon filling height of 1.6 meters, and a diameter of 0.5 meters. Activated carbon is coconut shell activated carbon with a specific surface area of 2800m ² /g. After decolorization, the material is a colorless liquid (≤5 color scale).

After that, the material is sent to the ion exchange system, and after being treated with anion, cation, and non-anion and non-cation exchange resins respectively, more than 99.999970% of electronic-grade butyl lactate products can be obtained (wherein the water content is less than 1mg/kg, butanol The content is less than 23.3 mg/kg, the lactic acid content is less than 2 mg/kg, and the metal ion content is less than 1.5 μg/kg). Anion, cation, and non-anion and non-cation exchange columns have a column height of 2 meters and a diameter of 0.5 meters. The resins filled are Amberlite IR120 Na type cation exchange resin, Amberlite IRA402 Cl type anion exchange resin and Amberlite ^TM XAD4 type macropore Absorbent resin.

The still residual liquid is discharged from the tower kettle at a flow rate of 1.03kg/h, and is sent to the residual liquid storage tank to be accumulated to a certain amount before centralized treatment.

Qualified products are sent to product storage tanks with nitrogen seals, and are shipped out after dust-free filling and sealing by automatic filling machines.

Example 6

(1) Send the crude ethyl lactate into the flasher at a rate of 1500kg/h, which contains 3130 mg/kg of ethanol, 1970 mg/kg of water, 2020 mg/kg of lactic acid, and a mass content of 99.2% of ethyl lactate. The impurity content of metal ions and heavy components is 980 mg/kg. The operating pressure of the flasher is 68KPa, and the operating temperature is about 140°C. About 65% of the water and low boiling substances such as ethanol in the crude ethyl lactate can be removed. The solution at the bottom of the flash evaporator is pumped into the middle of the light removal tower at a flow rate of 1173.41kg/h. SS304 stainless steel wire mesh structured packing is installed in the light removal tower, the number of theoretical plates is 30, the inner diameter of the tower is 0.13m, the operating pressure at the top of the tower is 60KPa, and the temperature is about 102°C. Low boilers such as water and ethanol are distilled from the top of the tower, and the reflux ratio is 10.0. Ethyl lactate and heavy components are discharged from the tank of the light removal tower at a flow rate of 1153.40kg/h, and are pumped to the feed port of the refining tower.

(2) The internal parts of the refining tower adopt SS316L stainless steel wire mesh structured packing, the number of theoretical plates is 150, the inner diameter of the tower is 0.33m, the operating pressure at the top of the tower is 60KPa, and the temperature is 137°C. The top of the refining tower produces ethyl lactate containing a small amount of water and low boilers such as ethanol, which is sent to the flash evaporator for recycling and separation, and the operating reflux ratio is 3.0. Ultra-high purity ethyl lactate (mass content 99.999938%) is extracted from the side line liquid phase at the upper part of the tower at a flow rate of 1145.40kg/h (the theoretical plate number from the extraction outlet to the top of the tower is 15), and then sent to the activated carbon decolorization system discoloration. The activated carbon decolorization system is a fixed bed decolorization column with a column height of 4 meters, an activated carbon filling height of 3.2 meters, and a diameter of 1.5 meters. Activated carbon is coconut shell activated carbon with a specific surface area of 2800m ² /g. After decolorization, the material is a colorless liquid (≤5 color scale).

After that, the material is sent to the ion exchange system, and after being treated with anion, cation, and non-anion and non-cation exchange resins respectively, more than 99.999965% of electronic grade ethyl lactate products can be obtained (wherein the water content is lower than 19.3mg/kg, ethanol The content is less than 7.8mg/kg, the lactic acid content is less than 4.7mg/kg, and the metal ion content is less than 2.4μg/kg). Anion, cation, non-anion and non-cation exchange columns have a column height of 4 meters and a diameter of 1.5 meters. The resins filled are Amberlite IR120 Na type cation exchange resin, Amberlite IRA402 Cl type anion exchange resin and Amberlite ^TM XAD4 type macropore Absorbent resin.

The still residual liquid is discharged from the tower kettle at a flow rate of 8.00kg/h, and is sent to the residual liquid storage tank to be accumulated to a certain amount before centralized treatment.

Qualified products are sent to product storage tanks with nitrogen seals, and are shipped out after dust-free filling and sealing by automatic filling machines.

Claims (6)

1. the production technique of an electronic-grade lactic acid ester product is characterized in that it may further comprise the steps:

Step 1. adds food grade or other suitable other lactate of level (hereinafter to be referred as the lactate bullion) of purity of 99.0% above purity in the flasher (1); Operate through vacuum flashing; Low-boiling-point substance such as contained 15% ~ 65% moisture content and alcohols will go out from flasher (1) evaporated on top with gaseous state in the solvent; After the evaporator overhead condenser condensation, discharge; Liquid phase material in the flasher (1) is discharged from flasher (1) bottom, and is sent to further processing of lightness-removing column (2), and the working pressure of flasher (1) is controlled at 5 ~ 100KPa; Service temperature is 68 ~ 142 ℃;

Step 2. is in lightness-removing column (2), and low-boiling-point substances such as remaining moisture content and alcohols obtain removing basically in the material, and distillate from cat head; Owing to wherein contain lactate,, send into then from the material of lightness-removing column (2) bottom discharge that treating tower (3) is further to be made with extra care so it is sent to flasher (1) separations that circulate once more; Described lightness-removing column (2) is a packing tower; Or the combined column of packing tower and tray column, theoretical plate number is 20 ~ 200, the cat head working pressure is 5 ~ 60KPa; The cat head service temperature is 34 ~ 102 ℃, and the trim the top of column ratio is 10.0 ~ 100.0;

Step 3. is in treating tower (3); The low-boiling-point substances such as denier moisture content and alcohol that remain in the material will be turned back in the flasher by extraction and circulation at cat head; Treating tower (3) but the lactate work in-process of then extraction ultra-high purity of top side line; The extraction position is 5 ~ 20 apart from the theoretical plate number of cat head, and it is sent to the activated carbon decolorizing system and further handles; The extraction of treating tower (3) bottom be a small amount of lactate with lactic acid and by the lactate bullion bring into by various impurity that are not vaporized removal such as spissated metals ion, whole high boiling material, solid substance, mechanical impuritys; Described treating tower (3) is a packing tower, or the combined column of packing tower and tray column, and theoretical plate number is 30 ~ 200, and the cat head working pressure is 5 ~ 60KPa, and the cat head service temperature is 70 ~ 137 ℃, and the trim the top of column ratio is 0.05 ~ 3.0;

The lactate work in-process of step 4. ultra-high purity of side line extraction on treating tower top; Prompt delivery deactivation carbon decoloring system (17) further handles; To remove pigment impurity or other impurity component wherein; Make the colourity of product reach requirement, used gac is a cocoanut active charcoal, or other specific surface area is equivalent to 1000-3000m ²The gac of/g;

Step 5. is through the lactate work in-process of the ultra-high purity after the decolouring; Get into ion exchange system again; Remove positively charged ion and negatively charged ion respectively; Or the neutral impurity of other metal ion; At last, by the lactate product of ion exchange system output be that purity is higher than more than 99.9999%, metal ion content is lower than 3ppb, colourless electronic-grade lactate product, described three ion exchange columns (18,19 and 20) are loaded Amberlite IR120 Na type Zeo-karb, Amberlite IRA402 Cl type anionite-exchange resin and AmberliteTM XAD4 type macroporous adsorbent resin respectively.

2. the production technique of electronic-grade lactic acid ester product according to claim 1 is characterized in that: the working pressure of the described flasher of step 1 (1) is 10 ~ 60KPa; Service temperature is 80 ~ 130 ℃.

3. the production technique of electronic-grade lactic acid ester product according to claim 1 is characterized in that: the theoretical plate number of the described lightness-removing column of step 2 is 30 ~ 120; Lightness-removing column cat head working pressure is 10 ~ 40KPa; Service temperature is 50 ~ 90 ℃; The reflux ratio of lightness-removing column is 0.3 ~ 1.5.

4. the production technique of electronic-grade lactic acid ester product according to claim 1 is characterized in that: the theoretical plate number of the described treating tower of step 3 is 40 ~ 150; Treating tower cat head working pressure is for being 10 ~ 40KPa; Service temperature is 80 ~ 120 ℃; The reflux ratio of treating tower is 0.3 ~ 1.5; The extraction position is 6 ~ 15 apart from the theoretical plate number of cat head.

5. the production technique of electronic-grade lactic acid ester product according to claim 1 is characterized in that: sepn process, comprise all storage tanks, and in nitrogen protection, adopt decompression operation; The all devices good seal must not leak gas when negative-pressure operation, necessary first pickling before the equipment internal surface feeds intake after manufacturing processed and installation finish and produces, and alkali cleaning, after high purity water cleans, for use behind the hot-air dry that cleans again.

6. the production technique of electronic-grade lactic acid ester product according to claim 1 is characterized in that: production plant is a dust-free workshop, through GMP design and authentication; Finished product is through dustless filling and sealing and storage.

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