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CN1546371A - Process for producing orthophosphorous acid from high boiling byproducts of dialkyl ester phosphite - Google Patents

Process for producing orthophosphorous acid from high boiling byproducts of dialkyl ester phosphite Download PDF

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Publication number
CN1546371A
CN1546371A CNA2003101090952A CN200310109095A CN1546371A CN 1546371 A CN1546371 A CN 1546371A CN A2003101090952 A CNA2003101090952 A CN A2003101090952A CN 200310109095 A CN200310109095 A CN 200310109095A CN 1546371 A CN1546371 A CN 1546371A
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phosphorous acid
acid
high boiling
reaction
dialkyl phosphite
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CN1288074C (en
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伟 王
王伟
周曙光
钟连发
王群孝
郑红朝
江东
杨访成
屠明海
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Zhejiang Xinan Chemical Industrial Group Co Ltd
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Zhejiang Xinan Chemical Industrial Group Co Ltd
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Abstract

The invention provides a novel method for disposing high boiling fraction produced in the procedure of phosphorous acid dialkyl ester production, wherein the molecular structural formula of the phosphorous acid dialkyl ester is (RO)2P(OH), R is C1-3 alkyl. The method includes charging halogen acid or letting in hydrogen halide into the high boiling fraction, thus producing acid hydrolysis reaction between phosphorous acid alkyl ester and polymer in the high boiling fraction to creat phosphorous acid, the alkoxy on the phosphono is acid hydrolyzed into halogenated hydrocarbon, wherein the outcome yield is the water solution of phosphorous acid, and the phosphorous acid crystallization is obtained from the water solution of phosphorous acid through condensation and crystallization.

Description

Method for producing phosphorous acid by using dialkyl phosphite byproduct high-boiling residue
One, the technical field
The invention relates to an improvement of a treatment process of a high-boiling residue generated in a dialkyl phosphite production process, in particular to a method for producing phosphorous acid and byproduct halohydrocarbon by using the high-boiling residue.
Second, background Art
Dialkyl phosphite of the molecular formula (RO)2P (OH), wherein R is alkyl with 1-3 carbon atoms, especially dimethyl phosphite and diethyl phosphite are important chemical raw materials and intermediates, and are widely applied to the preparation industries of organic phosphate type corrosion inhibitors, synthetic plastic additives, dye additives, flame retardants and pesticides. The water quality corrosion and scale inhibitor of organic phosphoric acid type and organic phosphonic acid-carboxylic acid type prepared by it is widely used for industrial and chemical circulating water treatment; the phosphite compounds prepared by the method are widely used as phosphorus additives with different functions in the plastic industry and additives in the dye industry and oil products; meanwhile, it is also an important intermediate for preparing organophosphorus pesticides such as trichlorphon, dichlorvos, fenoxanil, omethoate, glyphosate and the like. The domestic yield of dialkyl phosphite ester reaches 20 million tons. The production method is generally that corresponding alcohol (methanol, ethanol and the like) and phosphorus trichloride are directly reacted to prepare the compound, and the reaction equation is as follows:
(RO)3the acidolysis of P in the presence of hydrogen chloride to dialkyl phosphite:
in actual production, since hydrogen chloride generated in the moment of reaction is difficult to rapidly remove from the system, the following side reactions often occur:
therefore, during the production of dialkyl phosphite, considerable amount of monoalkyl phosphite and phosphorous acid is often generated and dissolved in the reaction product, which results in low yield of the main reaction, for example, the continuous solvent-free dimethyl phosphite process modification (No. 30, No. 11, 859-862 of petrochemical engineering, 2001) discloses that the yield of the process is 90%, which is the best technical level in China. The monoalkyl phosphite and phosphorous acid produced during the purification of the product (by rectification) at high temperature (100 ℃C. and 170 ℃ C.) form a polymer containing P-O-P bonds, which are collectively referred to as high boiling point by-products (hereinafter referred to as high boiling substances) in the present invention. In the prior art, this is produced in an amount of about 8-20% of the total product, and consists of: 10-70% of monoalkyl phosphite, 10-50% of phosphorous acid, 0.1-20% of polymer and 1-20% of dialkyl phosphite.
The invention patent with the application number of 97122386.1 discloses a method for producing industrial phosphorous acid by dimethyl phosphite wastewater, and the technical scheme is that the high-boiling-point substance is filtered to remove impurities, then reacts with water at 70-100 ℃, and is subjected to vacuum concentration and crystallization. The method changes the discarded byproducts into valuables, and obtains certain economic and social benefits, but because the hydrolysis reaction speed is very slow, the reaction time is very long, the equipment utilization rate is low, the energy consumption is high, and the recovered low-concentration methanol (20-80%) has poor quality and low added value.
Phosphorous acid has wide application, is a raw material for producing phosphite, synthetic fiber, organic phosphorus pesticide and the like, and is mainly prepared by using phosphorus trichloride as a main raw material through hydrolysis, dehydrochlorination and crystallization, wherein the chemical reaction formula is as follows:
however, the phosphorous acid production process using phosphorus trichloride as a raw material has high cost and poor market competitiveness.
Third, the invention
The invention aims to provide anovel process for converting high-boiling point byproducts generated in the dialkyl phosphite production process into industrial grade phosphorous acid and alkyl halide with high yield, so as to solve the problems of environmental pollution and insufficient utilization rate of high-boiling point substances in the dialkyl phosphite production in the prior art. Therefore, the invention adopts the following technical scheme:
a process for preparing phosphorous acid from the by-product high-boiling substance of dialkyl phosphite whose molecular structure formula is (RO)2And P (OH), wherein R is alkyl with 1-3 carbon atoms, and is a byproduct alkyl halide generated in the reaction process by reacting the high-boiling-point substance with halogen acid to generate phosphorous acid. The alkyl phosphite and polymer in the high boiling residue can be converted into phosphorous acid, the alkoxy on the phosphono group can be acidolyzed into halohydrocarbon, after the reaction is completed, the active carbon is used for decoloring, the product is concentrated and crystallized to obtain phosphorous acid crystal, and the mother liquor can be circularly used. Or adjusting the content of the phosphorous acid aqueous solution by supplementing water and concentrating without crystallization to obtain the phosphorous acid aqueous solution with the content of 40-85%.
The dialkyl phosphite in the above method is preferably dimethyl phosphite; the halogen acid is hydrochloric acid or hydrogen chloride gas.
The method for producing the phosphorous acid by utilizing the byproduct high-boiling residue of the dialkyl phosphite comprises the following steps of: the halogen acid is added into each ton of high-boiling residues, and the halogen acid contains 3-15 kmol of hydrogen halide. In order to convert alkoxy into alkyl halide with maximum yield, the hydrohalic acid can be added into the reaction kettle in excess, more preferably, the added hydrohalic acid (or hydrogen halide) is 5-10 kmol calculated by hydrogen halide per ton of high-boiling-point substance, the added hydrohalic acid can ensure that all esters in the high-boiling-point substance are hydrolyzed, but because the reaction temperature is higher, more hydrogen halide escapes in the reaction process, and the added hydrohalic acid needs to be in excess. The escaped hydrogen halide needs to be absorbed and recycled. If the amount of the halogen acid is insufficient, the reaction is incomplete, a small amount of phosphite is mixed in the phosphorous acid, which affects the quality, and naturally, by prolonging the reaction time, the phosphite reacts with water in the system to be hydrolyzed into phosphorous acid and alcohol, but the process is slow, and the yield of the alkyl halide is affected due to the insufficient amount of the halogen acid. If the addition amount of the halogen acid is too much, a large amount of halide ions still exist in the system after the reaction is finished, and the quality of the phosphorous acid is also influenced.
The method for producing the phosphorous acid by using the high-boiling residue byproduct of the dialkyl phosphite is characterized in that the reaction temperature of the high-boiling residue and the halogen acid is 60-120 ℃. The acidolysis reaction of the monoalkyl phosphite requires a relatively high temperature, and the reaction is heated until the reaction is completed. The reaction temperature is preferably 60 ℃ to 120 ℃, the reaction temperature is too low and too slow, and because more water exists in the system, when the reaction temperature exceeds 100 ℃, a large amount of water is vaporized, the temperature rises very slowly, the temperature gradually rises along with the reduction of the water content in the system, and when the phosphorous acid content in the system reaches 70-85 percent and no halogenated alkane is generated in the system, the reaction is considered to reach the end point.
The method for producing the phosphorous acid by using the byproduct high-boiling residue of the dialkyl phosphite, which comprises the following steps of concentrating, crystallizing and filtering phosphorous acid aqueous solution generated after reaction to obtain phosphorous acid crystals, wherein the concentration temperature of the phosphorous acid aqueous solution is 80-180 ℃, the vacuum degree is 0-0.099MPa, and the phosphorous acid is easy to oxidize, so that the content of phosphate radical in the product can be controlled, the following technical scheme can be adopted, namely ① reaction and concentration temperature do not exceed 180 ℃, and the phosphorous acid can be subjected to disproportionation reaction to produce the phosphoric acid and the phosphine when the temperature reaches 180 ℃ under normal pressure:
② reducing the oxygen content of the system is also effective in preventing oxidation of phosphorous acid to phosphoric acid.
The high boiling residue also contains some solid impurities, which must be removed by filtration, either before acidolysis or after the reaction, by filter press, simple suction filtration, high speed centrifugation, etc. The 20-200 mesh active carbon is added for decolorization before filtration, and the added active carbon has obvious filtration assisting effect and can improve the filtration efficiency.
The acidolysis reaction of the high boiling residues can be completed in a conventional kettle type reactor, and can also be continuously reacted by adopting a tower type reactor, a tubular type reactor and other reactors.
The method for producing the phosphorous acid by utilizing the byproduct high-boiling residue of the dialkyl phosphite further comprises the steps of absorbing tail gas generated in the reaction by using halogen acid to recycle hydrogen halide, and performing alkali washing and drying treatment to obtain the alkyl halide. And tail gas generated by the reaction is absorbed by halogen acid to recover hydrogen halide, and is subjected to alkali washing and drying treatment to obtain the alkyl halide. The tail gas generated in the reaction process mainly contains hydrogen halide, alkyl halide, water and a small amount of alcohol, and the hydrogen halide in the tail gas is recovered by an acid absorption tower and then dried to obtain the alkyl halide. The invention is characterized in that the tail gas generated by the reaction is absorbed by hydrochloric acid to recover hydrogen chloride, and is subjected to alkali washing and drying treatment to obtain the chloroalkyl, while the existing dialkyl phosphite production process is often provided with a recovery system for byproduct haloalkane and hydrogen halide. When the high-boiling residue byproduct of dimethyl phosphite is used for producing phosphorous acid, tail gas generated in the reaction is absorbed by hydrochloric acid to recover hydrogen chloride, and is subjected to alkali washing and drying treatment to obtain methyl chloride.
The new process for producing phosphorous acid and byproduct alkyl halide by using the dialkyl phosphite high-boiling point byproduct as the raw material has the beneficial effects that:
1. the method is used for treating the byproduct high-boiling residues to obtain industrial-grade phosphorous acid and methyl chloride, so that the utilization rate of raw materials for producing the dimethyl phosphite is very high, and the byproduct methyl chloride can be used for producing the methyl chlorosilane, thereby changing waste into valuable and creating remarkable economic and social benefits.
2. Solves the problem of dialkyl phosphite waste liquid pollution and realizes clean production.
3. The process is simple, the tail gas can be recycled to be halogenated hydrocarbon and also can be merged into the existing recycling operation system, the investment is low, and the effect is quick.
Fourthly, the attached figure 1 is a process flow chart of the invention.
Fifth, detailed description of the invention
Embodiments of the invention are further described below with reference to the accompanying drawings:
the practice of the present invention will be specifically described below by taking the by-produced high boiling product of dimethyl phosphite as an example, but the method and the technical parameters in the scheme are not to be construed as limiting the present invention.
Example 1
200g of filtered dimethyl phosphite byproduct high-boiling residue is added into a four-neck flask with a reflux condenser, 160g of hydrochloric acid is added, the content of the added hydrochloric acid is 20%, heating reaction is carried out, the highest reaction temperature is controlled to be 110 ℃, the concentration temperature is controlled to be 120 ℃, the concentration time is 20min, the concentration vacuum degree is 0.08MP, the reaction time is 162min, (the reaction end point is when no bubble escapes from an alkali washing bottle), and the tail gas is emptied after water washing and alkali washing. The phosphorous acid content was analyzed by reduction and the amount of methyl chloride produced was calculated by chlorine balance (analysis of chloride ion content in reactants, products, wash solution, loss of part to methyl chloride).
Example 2
200g of filtered dimethyl phosphite byproduct high-boiling residue is added into a four-neck flask with a reflux condenser, 160g of hydrochloric acid is added, the content of the added hydrochloric acid is 30%, heating reaction is carried out, the highest reaction temperature is controlled to be 110 ℃, the concentration time is 20min, the concentration vacuum degree is 0.08MP, the reaction time is 102min (the reaction end point is when no bubble escapes from an alkali washing bottle), and the tail gas is subjected to water washing and alkali washing and then is discharged. The phosphorous acid content was analyzed by reduction and the amount of methyl chloride produced was calculated by chlorine balance (analysis of chloride ion content in reactants, products, wash solution, loss of part to methyl chloride).
Example 3
200g of filtered dimethyl phosphite byproduct high-boiling residue is added into a four-neck flask with a reflux condenser, 160g of hydrochloric acid is added, the content of the added hydrochloric acid is 36%, heating reaction is carried out, the highest reaction temperature is controlled to be 110 ℃, the concentration temperature is controlled to be 120 ℃, the concentration time is 20min, the concentration vacuum degree is 0.08MP, the reaction time is 95min (the reaction end point is when no bubble escapes from an alkali washing bottle), and the tail gas is subjected to water washing and alkali washing and then is discharged. The phosphorous acid content was analyzed by reduction and the amount of methyl chloride produced was calculated by chlorine balance (analysis of chloride ion content in reactants, products, wash solution, loss of part to methyl chloride).
Example 4
200g of filtered dimethyl phosphite byproduct high-boiling residue was charged into a four-neck flask equipped with a reflux condenser, and 160g of distilled water was added. And introducing metered hydrogen chloride gas, heating, controlling the highest reaction temperature to be 120 ℃, the concentration temperature to be 120 ℃ and the concentration vacuum degree to be 0.08 MP. The reaction time is 90min (the end point of the reaction is when no air bubbles escape from the alkaline washing bottle), and the concentration time is 20 min. And (4) washing the tail gas with water and alkali, and then emptying. The phosphorous acid content was analyzed by reduction and the amount of methyl chloride produced was calculated by chlorine balance (analysis of chloride ion content in reactants, products, wash solution, loss of part to methyl chloride).
Example 5
200g of filtered dimethyl phosphite byproduct high-boiling residue is added into a four-neck flask with a reflux condenser, 200g of hydrochloric acid is added, the content of the added hydrochloric acid is respectively 13.7 percent, heating reaction is carried out, the reaction temperature is controlled to be 110 ℃, the concentration temperature is controlled to be 120 ℃, and the concentration vacuum degree is 0.08 MP. The reaction time is 181min (the end point of the reaction is when no air bubbles escape from the alkaline washing bottle), and the concentration time is 20 min. And (4) washing the tail gas with water and alkali, and then emptying. The phosphorous acid content was analyzed by reduction and the amount of methyl chloride produced was calculated by chlorine balance (analysis of chloride ion content in reactants, products, wash solution, loss of part to methyl chloride).
Example 6
Example 6 is a comparative example, with 160g of water instead of hydrochloric acid, the maximum reaction temperature being 110 ℃, the maximum concentration temperature being 120 ℃ and the concentration vacuum being 0.08 MP. The reaction time was 4 hours, the concentration time was 20min, and the other operations were the same as in example 1.
Table 1 shows the experimental results of examples 1-5 and comparative examples:
TABLE 1
Serial number Weight of high boiling residue (g) Phosphorous acid is folded into hundred weight (g) Methyl chloride (g) Phosphorous acid yield (ton/ton high boiling) Chloromethane yield (kg/ton high boiling)
1 200 164 40.4 0.820 197.0
2 200 171 58.7 0.855 293.5
3 200 173 69.8 0.865 324.0
4 200 171 70.2 0.855 351.0
5 200 162 27.0 0.810 135.0
Comparative example 6 200 157 0 0.785 0

Claims (9)

1. A process for preparing phosphorous acid from the by-product high-boiling substance of dialkyl phosphite whose molecular structure formula is (RO)2And P (OH), wherein R is alkyl with 1-3 carbon atoms, and is characterized in that the high-boiling-point substance reacts with halogen acid to generate phosphorous acid, and tail gas generated in the reaction process contains a byproduct alkyl halide.
2. The method for producing phosphorous acid from a high boiling by-product of dialkyl phosphite as set forth in claim 1, wherein said dialkyl phosphite is dimethyl phosphite.
3. The method for producing phosphorous acid from a high boiling by-product of dialkyl phosphite as set forth in claim 2, wherein said hydrohalic acid is hydrochloric acid or hydrogen chloride gas, and said by-product alkyl halide is methyl chloride.
4. The method for producing phosphorous acid from the byproduct high boiling substance of dialkyl phosphite as set forth in any of claims 1-3, wherein the ratio of halogen acid to high boiling substance is: the halogen acid is added into each ton of high-boiling residues, and the halogen acid contains 3-15 kmol of hydrogen halide.
5. The method for producing phosphorous acid from the byproduct high boiling substance of dialkyl phosphite as set forth in claim 4, wherein the reaction temperature of the reaction between the high boiling substance and halogen acid is 60-120 ℃.
6. The method for producing phosphorous acid from a high boiling by-product of dialkyl phosphite as set forth in claim 4, wherein said method further comprises concentrating, crystallizing and filtering the aqueous solution of phosphorous acid to obtain crystals of phosphorous acid.
7. The method for producing phosphorous acid from the byproduct high boiling substance of dialkyl phosphite as set forth in claim 6, wherein the concentration temperature of the aqueous solution of phosphorous acid is 80-180 ℃ and the vacuum degree is 0-0.099 MPa.
8. The method for producing phosphorous acid from the byproduct high boiling substance of dialkyl phosphite as claimed in claim 4, further comprising recovering hydrogen halide from the tail gas generated by the reaction through halogen acid absorption, and performing alkali washing and drying treatment to obtain alkyl halide.
9. The method for producing phosphorous acid by using the byproduct high boiling residue of dialkyl phosphite as set forth in claim 8, wherein said dialkyl phosphite is dimethyl phosphite, and said method further comprises the steps of absorbing the tail gas generated by the reaction with hydrochloric acid to recover hydrogen chloride, and performing alkali washing and drying treatment to obtain methyl chloride.
CN 200310109095 2003-12-02 2003-12-02 Process for producing orthophosphorous acid from high boiling byproducts of dialkyl ester phosphite Expired - Lifetime CN1288074C (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102633241A (en) * 2012-04-15 2012-08-15 湖北泰盛化工有限公司 Method for recovering phosphorous acid by acidolysis of dimethyl phosphite distillation residual liquid
CN105753899A (en) * 2016-03-19 2016-07-13 安徽东至广信农化有限公司 Recovery method of rectification residual liquid of dimethyl phosphite
WO2022077813A1 (en) * 2020-10-12 2022-04-21 江苏利思德新材料有限公司 Poly/mono-hypophosphite hydrogen diphosphite compound, and preparation and use thereof

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102633241A (en) * 2012-04-15 2012-08-15 湖北泰盛化工有限公司 Method for recovering phosphorous acid by acidolysis of dimethyl phosphite distillation residual liquid
CN105753899A (en) * 2016-03-19 2016-07-13 安徽东至广信农化有限公司 Recovery method of rectification residual liquid of dimethyl phosphite
WO2022077813A1 (en) * 2020-10-12 2022-04-21 江苏利思德新材料有限公司 Poly/mono-hypophosphite hydrogen diphosphite compound, and preparation and use thereof
US12180351B2 (en) 2020-10-12 2024-12-31 Jiangsu Liside New Material Co., Ltd. Condensate of poly/mono-phosphorous acid and aluminum hydrogen phosphate, preparation and application thereof

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