CN108409941B - Clean production process of solid epoxy resin - Google Patents
Clean production process of solid epoxy resin Download PDFInfo
- Publication number
- CN108409941B CN108409941B CN201810240701.0A CN201810240701A CN108409941B CN 108409941 B CN108409941 B CN 108409941B CN 201810240701 A CN201810240701 A CN 201810240701A CN 108409941 B CN108409941 B CN 108409941B
- Authority
- CN
- China
- Prior art keywords
- lignin
- epoxy resin
- production process
- cardanol
- clean production
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/02—Polycondensates containing more than one epoxy group per molecule
- C08G59/04—Polycondensates containing more than one epoxy group per molecule of polyhydroxy compounds with epihalohydrins or precursors thereof
- C08G59/06—Polycondensates containing more than one epoxy group per molecule of polyhydroxy compounds with epihalohydrins or precursors thereof of polyhydric phenols
- C08G59/063—Polycondensates containing more than one epoxy group per molecule of polyhydroxy compounds with epihalohydrins or precursors thereof of polyhydric phenols with epihalohydrins
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08H—DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS
- C08H6/00—Macromolecular compounds derived from lignin, e.g. tannins, humic acids
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Engineering & Computer Science (AREA)
- Biochemistry (AREA)
- Materials Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Epoxy Resins (AREA)
- Epoxy Compounds (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
The invention belongs to the technical field of chemical industry, and particularly relates to a clean production process of solid epoxy resin. The method comprises the following steps: extracting lignin from the papermaking black liquor by using an acid extraction and alcohol precipitation method; and then modifying the lignin into hydroxymethylated lignin by using a formaldehyde aqueous solution, and further modifying the lignin into cardanol modified lignin by using cardanol. Adding the cardanol modified lignin, epichlorohydrin and a phase transfer catalyst into a reaction kettle, and adding alkali liquor while stirring for reaction. And (3) adjusting the obtained solution to be neutral by using alkene hydrochloric acid, removing excessive epichlorohydrin by reduced pressure distillation, washing the solution to be neutral by using water, and drying the solution in vacuum to obtain solid powdery epoxy resin. The method takes the waste liquid of paper making industry and cardanol as raw materials, is nontoxic and degradable, saves energy and protects environment, simultaneously solves the problem of insufficient toughness of the epoxy resin, and has the advantages that the yield of the prepared epoxy resin is up to more than 99 percent and the epoxy value also reaches a more ideal state.
Description
Technical Field
The invention belongs to the technical field of chemical industry, and particularly relates to a clean production process of solid epoxy resin.
Background
The epoxy resin has excellent chemical and chemical properties: low shrinkage, high bonding strength, high mechanical strength, good electrical insulation and the like, and is widely applied to various fields of production and life. However, most of the production raw materials are derived from petrochemical engineering, and the bisphenol A type epoxy resin has high dependence on petroleum and the widest application range, and is toxic, pollutes the environment and is harmful to human health. Therefore, the preparation of high-performance epoxy resins by using new materials is the focus of research.
Lignin is the only non-petroleum resource in nature which can provide renewable aromatic compounds, widely exists in higher plants, and forms the main structure of the plants together with cellulose and hemicellulose, the quantity of the lignin is only equal to that of the cellulose, and the lignin is the second organic matter in the world. With the increasing exhaustion of petroleum resources on the earth, people pay more attention to the development and utilization of renewable lignin. The lignin contains a large amount of active groups such as phenolic hydroxyl, alcoholic hydroxyl, methoxyl, carboxyl and the like, and obviously can play an important role in the synthesis of epoxy resin.
Meanwhile, a large amount of lignin exists in black liquor generated in the paper making industry, namely alkaline black liquor left after cellulose used for paper making in plants is extracted and separated. In the past concept, the black liquor is generally considered to be waste liquor, is directly incinerated, wastes a large amount of energy and causes secondary pollution to the environment. If this part of lignin is extracted and used for synthesizing epoxy resin, it has many advantages.
At present, lignin is utilized to synthesize epoxy resin, and two ways are mainly adopted. One is to synthesize epoxy resin by directly using lignin, but the epoxy value is generally low. The other is to modify lignin in various ways and then synthesize epoxy resin by using the modified lignin, but the other has the problems of low chemical activity of lignin, insufficient toughness of the synthesized epoxy resin and the like. Therefore, it is of great practical significance to develop a new technical scheme for the method for synthesizing the epoxy resin by taking the lignin as the raw material.
Disclosure of Invention
The invention aims to provide a clean production process of solid epoxy resin.
In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows: a clean production process of solid epoxy resin comprises the following steps:
(1) extracting lignin from the papermaking black liquor, uniformly mixing the papermaking black liquor and absolute ethyl alcohol according to the volume ratio of 1: 1-1: 1.5, carrying out primary water bath for 1-3 h at the temperature of 45-75 ℃, standing for layering, and taking supernatant; evaporating the supernatant to remove ethanol, slowly adding concentrated sulfuric acid or concentrated nitric acid with the pH value of 2, heating the solution in a water bath at 45-75 ℃ for 6-7 hours again until no more precipitate is generated in the solution, centrifuging the solution and the precipitate, drying and centrifuging the obtained solid to obtain lignin;
(2) the cardanol modified lignin is prepared by uniformly mixing the lignin obtained in the step (1) with 35% formaldehyde aqueous solution according to the mass ratio of 1:1, adjusting the pH value to 12 by using sodium hydroxide, and stirring and reacting at 95 ℃ for 3 hours to obtain hydroxymethylated lignin;
adding cardanol with the mass being half of that of the lignin, stirring at 95 ℃ for reaction, adjusting the pH value of the solution to be 2 by using dilute hydrochloric acid after the reaction is completed, and precipitating to obtain cardanol modified lignin;
(3) adding cardanol modified lignin and epoxy chloropropane into a reaction kettle according to the mass ratio of 1: 6-20, stirring and heating to 50-100 ℃, and adding a phase transfer catalyst with the mass being 5% of that of the cardanol modified lignin; and then adding alkali liquor while stirring, adding 1-10 ml of alkali liquor into 1g of cardanol modified lignin, preserving heat for 1-5 hours, adjusting the obtained solution to be neutral by using dilute hydrochloric acid, carrying out reduced pressure distillation to remove excessive epoxy chloropropane, washing the distillation concentrate to be neutral, and carrying out vacuum drying to obtain the solid powdery epoxy resin.
Preferably, the volume ratio of the papermaking black liquor to the absolute ethyl alcohol in the step (1) is 1:1, the primary water bath temperature and the secondary water bath temperature are both 75 ℃, and the primary water bath time and the secondary water bath time are both 3 h.
Preferably, the alkali liquor in the step (3) is 10% sodium hydroxide.
Preferably, the phase transfer catalyst in step (3) is one of tetramethylammonium chloride, hexadecyltributyl phosphonium bromide and benzyltrimethylammonium chloride.
Preferably, the phase transfer catalyst in step (3) is hexadecyl tributyl phosphonium bromide.
Preferably, the mass ratio of the cardanol modified lignin to the epichlorohydrin in the step (3) is 1:6 or 1: 10.
Preferably, when the mass ratio of the cardanol modified lignin to the epichlorohydrin is 1:6, the temperature rise temperature is 95 ℃, and the addition amount of the alkali liquor is as follows: adding 2ml of alkali liquor into 1g of cardanol modified lignin, and keeping the temperature for 2 hours.
Preferably, when the mass ratio of the cardanol modified lignin to the epichlorohydrin is 1:10, the temperature rise temperature is 70 ℃, and the addition amount of the alkali liquor is as follows: 1ml of alkali liquor is added into 1g of cardanol modified lignin, and the heat preservation time is 4 hours.
Correspondingly, the novel solid epoxy resin is prepared by using the clean production process.
The invention has the following beneficial effects:
1. the lignin extracted from the waste liquor of the paper making industry is used as a raw material to replace bisphenol A in the traditional process, so that a large amount of energy is saved, and the lignin is non-toxic, biodegradable, environment-friendly and green.
2. The method creatively utilizes cardanol to modify lignin, wherein the cardanol comes from cashew shells in the cashew nut production process and belongs to waste reutilization; meanwhile, the problem of insufficient toughness of the epoxy resin is effectively solved.
3. The solid epoxy resin production process provided by the invention has the advantages that the yield of the epoxy resin is up to more than 99%, and the epoxy value also reaches a relatively ideal state.
4. During the production of epoxy resin, epoxy chloropropane is required to be used in excess by multiple times, and the excess epoxy chloropropane cannot be completely collected for reuse, so that a large amount of waste is caused, and the environment can be polluted. Under the specific technical scheme provided by the invention, the effect of using a plurality of times of excess epichlorohydrin can be achieved by using a lower amount of epichlorohydrin.
Detailed Description
The operation steps of the invention are as follows:
1. acid extraction and alcohol precipitation method, extracting lignin from papermaking black liquor.
Uniformly mixing commercially available papermaking black liquor and absolute ethyl alcohol according to the volume ratio of 1: 1-1: 1.5, carrying out water bath for 1-3 h at the temperature of 45-75 ℃, standing for layering, and taking supernatant. Evaporating the supernatant to remove ethanol (recycling the ethanol) to obtain an alcohol-free solution, slowly adding concentrated sulfuric acid or concentrated nitric acid into the solution while stirring until the pH value is 2, and then heating the solution in a water bath at 45-75 ℃ for 6-7 h again until lignin is basically separated and precipitated. When no more precipitate is generated in the solution, centrifuging the solution and the precipitate at 10000r/min, and drying the solid obtained by centrifuging to obtain the lignin required by the invention.
2. The cardanol is used for modifying lignin.
(1) Uniformly mixing the lignin obtained in the step 1 and 35% formaldehyde aqueous solution according to the mass ratio of 1:1, adjusting the pH value to 12 by using sodium hydroxide, and stirring and reacting for 3 hours at 95 ℃ to obtain hydroxymethylated lignin.
(2) And (2) adding a certain amount of cardanol into the solution containing hydroxymethylated lignin obtained in the step (1), wherein the addition amount of cardanol is half of the mass of the lignin added in the step (1), stirring and reacting for 3 hours at 95 ℃, adjusting the pH value of the solution to be 2 by using dilute hydrochloric acid after the reaction is completed, and precipitating to obtain cardanol modified lignin.
3. Synthesizing epoxy resin by using cardanol modified lignin.
Adding the cardanol modified lignin and epoxy chloropropane into a reaction kettle according to the mass ratio of 1: 6-20, stirring, heating to 50-100 ℃, and adding a phase transfer catalyst (tetramethylammonium chloride, hexadecyltributyl phosphorus bromide and benzyltrimethylammonium chloride), wherein the mass of the catalyst is 5% of that of the cardanol modified lignin.
Stirring, adding alkali liquor (10% of sodium hydroxide) while stirring, adding 1-10 ml of alkali liquor into 1g of lignin, keeping the temperature for 1-5 h, adjusting the obtained solution to be neutral by using 0.1mol/L hydrochloric acid, carrying out reduced pressure distillation to remove excessive epichlorohydrin, washing the distillation concentrate to be neutral, and carrying out vacuum drying to obtain the solid powdery epoxy resin.
Example 1: selection of parameters for extraction of lignin
(1) The lignin was extracted using step 1 of the above procedure, and the specific parameters of each group are shown in table 1.
TABLE 1 detailed parameter table for each group
(2) The average yield of lignin in each group was 86%, with the highest yield of group 4, reaching 97%. Thus, the parameters of group 4 are selected for subsequent operations.
Example 2: parameter selection for synthesizing epoxy resin by using cardanol modified lignin
(1) Lignin was extracted using the method of example 1, group 4, using step 2 of the procedure, the extracted lignin was cardanol modified.
(2) Using step 3 of the procedure, epoxy resins were synthesized, with specific parameters for each group as shown in table 2.
TABLE 2 detailed parameter table for each group
(3) Analysis of results
The epoxy resin yield and epoxy amount of each group are shown in table 3.
TABLE 3 results of each group
| Group of | Yield of epoxy resin | Cyclic oxygen amount (mol/100g) |
| 1 | 99.2％ | 0.47 |
| 2 | 99.0％ | 0.45 |
| 3 | 99.2％ | 0.43 |
| 4 | 85.9％ | 0.31 |
| 5 | 93.3％ | 0.40 |
| 6 | 93.2％ | 0.25 |
| 7 | 95.1％ | 0.30 |
| 8 | 98.1％ | 0.27 |
| 9 | 98.3％ | 0.29 |
| 10 | 98.2％ | 0.31 |
| 11 | 98.3％ | 0.31 |
| 12 | 99.0％ | 0.27 |
| 13 | 84.0％ | 0.23 |
| 14 | 84.5％ | 0.25 |
| 15 | 97.7％ | 0.38 |
| 16 | 99.2％ | 0.47 |
| 17 | 99.3％ | 0.47 |
(1) As shown in the table, when the addition amount of the epichlorohydrin is 10 times that of the cardanol modified lignin, the maximum yield of the epoxy resin can be achieved, the amount of the epichlorohydrin is continuously increased, and the yield cannot be continuously increased. Meanwhile, the epoxy value also shows a trend of decreasing with the increase of the dosage of the epoxy chloropropane.
(2) Groups 1 and 13-16 show that the yield is close to the limit when the reaction is carried out for 4 hours, and the yield can not be increased continuously when the time is increased.
(3) The yield and epoxy value are the best results with the parameters of group 1. However, the applicant finds that, when operating under the technical scheme of the invention, under the parameters of the group 17, the amount of the epichlorohydrin is small, and the heat preservation time is shorter, but the effect similar to or even slightly superior to that of the group 1 can still be achieved. This may be a specific property of the cardanol-modified lignin, and may also be an unknown effect occurring between specific amounts of components.
Claims (9)
1. A clean production process of solid epoxy resin is characterized by comprising the following steps: the method comprises the following steps:
(1) extracting lignin from the papermaking black liquor, uniformly mixing the papermaking black liquor and absolute ethyl alcohol according to the volume ratio of 1: 1-1: 1.5, carrying out primary water bath for 1-3 h at the temperature of 45-75 ℃, standing for layering, and taking supernatant; evaporating the supernatant to remove ethanol, slowly adding concentrated sulfuric acid or concentrated nitric acid until the pH value is 2, heating the solution in a water bath at 45-75 ℃ for 6-7 hours again until no more precipitate is generated in the solution, centrifuging the solution and the precipitate, and drying and centrifuging the obtained solid to obtain lignin;
(2) the cardanol modified lignin is prepared by uniformly mixing the lignin obtained in the step (1) with 35% formaldehyde aqueous solution according to the mass ratio of 1:1, adjusting the pH value to 12 by using sodium hydroxide, and stirring and reacting at 95 ℃ for 3 hours to obtain hydroxymethylated lignin;
adding cardanol with the mass being half of that of the lignin, stirring at 95 ℃ for reaction, adjusting the pH value of the solution to 2 by using dilute hydrochloric acid after the reaction is completed, and precipitating to obtain cardanol modified lignin;
(3) adding cardanol modified lignin and epoxy chloropropane into a reaction kettle according to the mass ratio of 1: 6-20, stirring and heating to 50-100 ℃, and adding a phase transfer catalyst with the mass being 5% of that of the cardanol modified lignin; and then adding alkali liquor while stirring, adding 1-10 ml of alkali liquor into 1g of cardanol modified lignin, preserving heat for 1-5 hours, adjusting the obtained solution to be neutral by using dilute hydrochloric acid, carrying out reduced pressure distillation to remove excessive epoxy chloropropane, washing the distillation concentrate to be neutral, and carrying out vacuum drying to obtain the solid powdery epoxy resin.
2. The clean production process of the solid epoxy resin according to claim 1, characterized in that: the volume ratio of the papermaking black liquor to the absolute ethyl alcohol in the step (1) is 1:1, the primary water bath temperature and the secondary water bath temperature are both 75 ℃, and the primary water bath time is 3 hours.
3. The clean production process of the solid epoxy resin according to claim 1, characterized in that: the alkali liquor in the step (3) is 10% of sodium hydroxide.
4. The clean production process of the solid epoxy resin according to claim 1, characterized in that: the phase transfer catalyst in the step (3) is one of tetramethylammonium chloride, hexadecyl tributyl phosphonium bromide and benzyl trimethyl ammonium chloride.
5. The clean production process of the solid epoxy resin according to claim 1, characterized in that: the phase transfer catalyst in the step (3) is hexadecyl tributyl phosphonium bromide.
6. The clean production process of the solid epoxy resin according to claim 1, characterized in that: the mass ratio of the cardanol modified lignin to the epichlorohydrin in the step (3) is 1:6 or 1: 10.
7. The clean production process of the solid epoxy resin according to claim 6, characterized in that: when the mass ratio of the cardanol modified lignin to the epichlorohydrin is 1:6, the temperature rise temperature is 95 ℃, and the addition amount of the alkali liquor is as follows: adding 2ml of alkali liquor into 1g of cardanol modified lignin, and keeping the temperature for 2 hours.
8. The clean production process of the solid epoxy resin according to claim 6, characterized in that: when the mass ratio of the cardanol modified lignin to the epichlorohydrin is 1:10, the temperature rise is 70 ℃, and the addition amount of the alkali liquor is as follows: 1ml of alkali liquor is added into 1g of cardanol modified lignin, and the heat preservation time is 4 hours.
9. A solid epoxy resin characterized by: prepared by using the clean production process of claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810240701.0A CN108409941B (en) | 2018-03-22 | 2018-03-22 | Clean production process of solid epoxy resin |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810240701.0A CN108409941B (en) | 2018-03-22 | 2018-03-22 | Clean production process of solid epoxy resin |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108409941A CN108409941A (en) | 2018-08-17 |
| CN108409941B true CN108409941B (en) | 2020-03-24 |
Family
ID=63132370
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810240701.0A Active CN108409941B (en) | 2018-03-22 | 2018-03-22 | Clean production process of solid epoxy resin |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108409941B (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102675592A (en) * | 2012-06-08 | 2012-09-19 | 吉林大学 | Synthesizing method of epoxy resin by autocatalysis of lignin |
| CN102775568A (en) * | 2012-07-27 | 2012-11-14 | 山东圣泉化工股份有限公司 | Preparation method of modified phenolic resin |
| CN103756060A (en) * | 2013-12-16 | 2014-04-30 | 华南理工大学 | Rubber composite material filled by cardanol modified lignin and preparation method thereof |
| CN106750067A (en) * | 2016-12-16 | 2017-05-31 | 沙县宏盛塑料有限公司 | A kind of preparation method of lignin Cardanol Modified PF Resin |
-
2018
- 2018-03-22 CN CN201810240701.0A patent/CN108409941B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102675592A (en) * | 2012-06-08 | 2012-09-19 | 吉林大学 | Synthesizing method of epoxy resin by autocatalysis of lignin |
| CN102775568A (en) * | 2012-07-27 | 2012-11-14 | 山东圣泉化工股份有限公司 | Preparation method of modified phenolic resin |
| CN103756060A (en) * | 2013-12-16 | 2014-04-30 | 华南理工大学 | Rubber composite material filled by cardanol modified lignin and preparation method thereof |
| CN106750067A (en) * | 2016-12-16 | 2017-05-31 | 沙县宏盛塑料有限公司 | A kind of preparation method of lignin Cardanol Modified PF Resin |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108409941A (en) | 2018-08-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101348558B (en) | Enzymatic hydrolysis lignin epoxide resin and preparation thereof | |
| CN110241644B (en) | Method for separating and comprehensively utilizing all components of crop straws | |
| CN100528926C (en) | Enzymatic hydrolysis lignin epoxy resin material formula and its preparation method | |
| CN101864683A (en) | Pretreatment method of wood fiber raw materials | |
| CN106750179B (en) | A kind of preparation method of enzymolysis xylogen base epoxy | |
| CN105754114A (en) | Method for separating and extracting straw lignin by using eutectic ionic liquid | |
| CN101279722A (en) | Extraction liquid and extraction method for sulphuric acid in sulfuric acid hydrolysate prepared with plant fibre | |
| CN102690423B (en) | Method for producing sodium lignosulphonate by utilizing residues obtained by producing ethanol with crop straws as raw materials | |
| CN102864672A (en) | Method for extracting lignin | |
| CN105713050B (en) | A kind of method that degradation selectivity corncob hemicellulose improves xylose yield | |
| CN103031762B (en) | Method for preparing material rich in cellulose in degradable ionic liquid solvent | |
| CN109082251B (en) | Preparation method of environment-friendly urea-formaldehyde resin adhesive | |
| CN106750360A (en) | A kind of method of the reverse solution system separating lignin of utilization alkali ionic liquid | |
| CN108409941B (en) | Clean production process of solid epoxy resin | |
| CN101058628A (en) | Lignin modified phenol furfural resin for moulding material and preparation method thereof | |
| CN101323632A (en) | Microwave radiation preparation of acetic acid lignin | |
| CN114108350B (en) | Method for quickly separating main components of wood biomass by using eutectic solvent | |
| CN104293258B (en) | A kind of method of papermaking wastewater recycling and the adhesive that adopts the method to produce | |
| CN113698625B (en) | Pretreatment method of lignocellulose raw material | |
| CN113441115B (en) | Preparation method and application of lignin-based heavy metal adsorption and soil improvement repairing agent | |
| CN114105739B (en) | Green alkali lignin micromolecule separation method and product | |
| JP6274478B2 (en) | Method for producing lignin degradation product | |
| CN109467675A (en) | A kind of preparation method of epoxyn | |
| CN105220552B (en) | Using the method for the asymmetric Gemini ionic liquid extracts cellulose of imidazoles | |
| CN101274946A (en) | Method for extracting lignose from crops leftovers |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| CB02 | Change of applicant information |
Address after: 245900 Changsheng Road, Yao Cun village, Yansi Town, Huizhou District, Huangshan City, Anhui, 9 Applicant after: Mount Huangshan Wuhuan Technology Co., Ltd. Address before: 245900 Changsheng Road, Circular Economy Park, Huizhou District, Huangshan City, Anhui 9 Applicant before: Huangshan City Huizhou Wuhuan Chemical Industry Co., Ltd. |
|
| CB02 | Change of applicant information | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |