CN112358213A - Water permeable material and application thereof - Google Patents
Water permeable material and application thereof Download PDFInfo
- Publication number
- CN112358213A CN112358213A CN202011242186.3A CN202011242186A CN112358213A CN 112358213 A CN112358213 A CN 112358213A CN 202011242186 A CN202011242186 A CN 202011242186A CN 112358213 A CN112358213 A CN 112358213A
- Authority
- CN
- China
- Prior art keywords
- water
- permeable material
- water permeable
- sand particles
- permeable
- 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.)
- Pending
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/10—Coating or impregnating
- C04B20/1018—Coating or impregnating with organic materials
- C04B20/1029—Macromolecular compounds
- C04B20/1037—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/02—Treatment
- C04B20/04—Heat treatment
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C11/00—Details of pavings
- E01C11/22—Gutters; Kerbs ; Surface drainage of streets, roads or like traffic areas
- E01C11/224—Surface drainage of streets
- E01C11/225—Paving specially adapted for through-the-surfacing drainage, e.g. perforated, porous; Preformed paving elements comprising, or adapted to form, passageways for carrying off drainage
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Structural Engineering (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Road Paving Structures (AREA)
Abstract
The invention provides a water permeable material which is characterized by comprising silica sand particles, wherein the silica sand particles are uniformly coated with an adhesive to form precoated sand, and the dense stacking pores of the precoated sand particles are smaller than 100 mu m. The permeable material is used for preparing permeable prefabricated parts or directly paved into permeable pavements. After the water permeable material is prepared into a water permeable prefabricated part such as a water permeable brick or a water permeable pavement, the gap structure among particles is smooth and soft, and the water permeable material has certain anti-blocking performance; meanwhile, the accumulated pores are small, so that the pollutants SS (solid suspended matters) of the outburst road runoff can be intercepted.
Description
Technical Field
The invention relates to a building material, in particular to a water permeable material and application thereof.
Background
In order to realize the coordinated development of urbanization and natural resource environment, protect urban water ecosystem, reduce rainwater disasters and develop rainwater resources, urban roads and square pavements have certain water permeability so as to play roles in infiltration, detention, storage and purification of rainwater, so that the research on water permeable materials in building materials is always promising.
The existing permeable materials such as ceramic-based or cement-based permeable materials have rough gaps after forming building materials such as permeable bricks, and are easy to intercept suspended particles so as to block, and finally influence the water permeability of the permeable bricks.
Disclosure of Invention
In view of the above, it is an object of the present invention to provide a new water permeable material and its use, which is capable of achieving a better balance between suspended particles retention and drainage.
The invention provides a water permeable material which comprises silica sand particles, wherein the silica sand particles are uniformly coated with an adhesive to form precoated sand, and the dense stacking pores of the precoated sand particles are smaller than 100 mu m.
The size of the dense stacking pores of the precoated sand particles is less than 85 microns.
The pore size of the densely packed grain size of the precoated sand particles is less than 75 μm.
The dense packing particle size of the precoated sand particles is larger than 15 mu m.
The effective porosity of the water permeable material prepared into the water permeable block is 15-35%. Effective porosity refers to the effective pore volume/apparent volume of the water permeable block. The effective pores are communicated pores which can effectively permeate water. Unlike void pores (non-through pores), the high proportion of void pores contributes to the water permeability of the material.
The effective porosity of the permeable material prepared into the permeable block is about 21.5-22.5%.
The particle size range of the silica sand particles is 0.1mm-1 mm.
And roasting the precoated sand particles at high temperature.
The coated sand particles are roasted for 2-4 hours at the temperature of 750-1000 ℃.
The precoated sand particles have smooth surfaces and no protruding edges.
The adhesive is hydrophilic. The hydrophilic binder may be a hydrophilic substance known to those skilled in the art to function as a binder, for example a hydrophilic resin such as a hydrophilic epoxy resin and/or a hydrophilic polyurethane resin.
The invention also provides the application of the permeable material, and the permeable material is used for preparing the permeable prefabricated member or directly paved into a permeable pavement.
Has the advantages that:
after the permeable material is prepared into a permeable prefabricated part such as a permeable brick or a permeable pavement, the gap structure among the particles is smooth and soft, and has certain anti-blocking performance; meanwhile, the accumulated pores are small, so that the pollutants SS (solid suspended matters) of the outburst road runoff can be intercepted.
Drawings
FIG. 1 is a microscope comparison of raw sand and precoated sand;
FIG. 2 is a SEM comparison of the pores of the water permeable bricks;
FIG. 3 is a graph of the frequency of road dust in four seasons in Beijing urban area;
FIG. 4 is a graph of accumulated frequency of road dust in four seasons of Beijing urban area;
FIG. 5 is a graph of the average removal rate of suspensions with different particle diameters from a coated sand surface layer and a common concrete base layer composite water permeable brick;
fig. 6 is a picture of average removal rate of suspensions with different particle sizes from a common concrete water permeable brick.
Detailed Description
The structure and features of the present invention will be described in detail below with reference to the accompanying drawings and examples. It should be noted that various modifications can be made to the embodiments disclosed herein, and therefore, the embodiments disclosed in the specification should not be construed as limiting the present invention, but merely as exemplifications of embodiments thereof, which are intended to make the features of the present invention obvious.
The invention provides a water permeable material which comprises silica sand particles, wherein the silica sand particles are uniformly coated with an adhesive to form precoated sand, and the dense stacking pores of the precoated sand particles are smaller than 100 mu m. The silica sand can be aeolian sand, and the main component is silicon dioxide. Silica sand particles wrap the adhesive to form precoated sand, and the surface of the precoated sand needs to be smooth and has no protruding edges.
In order to ensure that the permeable material has better strength performance after being prepared into a permeable product, the coated sand particles are roasted for 2-4 hours at the temperature of 750-1000 ℃.
In order to further adjust the dense packing pores of the precoated sand particles, the particle size range of the silica sand particles is set to 0.1mm to 1 mm.
The preferred range of silica sand particle size is 0.1-0.5 mm. The size of the dense packed pores of the precoated sand particles is in the range of 15-85 μm.
The effective porosity of the water permeable material prepared into the water permeable block is 15-35%. Effective porosity refers to the effective pore volume/apparent volume of the water permeable block. The effective pores are communicated pores which can effectively permeate water. Unlike void pores (non-through pores), the high proportion of void pores contributes to the water permeability of the material.
The adhesive uniformly coated on the silica sand particles is organic material modified cement.
Example 1 comparative strength test of precoated sand
(1) Carrying out strength comparison on the silica sand particles and the precoated sand:
the results of the breaking rate of the silica sand particles (raw sand) and precoated sand at 28MPa and the dry-wet strength (prepared according to the water permeable brick resin curing agent test standard) of the cylindrical sample block prepared by bonding the silica sand particles with a water permeable adhesive are shown in the following table.
TABLE 1 precoated sand particle Strength
As can be seen from the above table, after the silica sand wraps the adhesive to form the precoated sand, the overall strength is improved, the dry strength is improved by 9.7% after the silica sand is bonded into a sample block by the water-permeable adhesive, the wet strength is improved by more than 50%, and the strength after the silica sand particles are bonded with the water-permeable adhesive and the water resistance of the formed material can be obviously improved by the modification of the adhesive interface.
(2) The precoated sand obtained more strength after high-temperature roasting, and the results are shown in the following table.
TABLE 1 influence of roasting on precoated sand test block strength
Example 2 pore Structure comparison test of precoated sand
(1) Morphological contrast analysis
The surface of the silica sand particles is uniformly coated with a layer of transparent adhesive to form precoated sand, the appearance form is shown in comparison in figure 1, figure 1(a) is a microscopic picture of the silica sand particles (raw sand), figure 1(b) is a microscopic picture of the precoated sand, and the surface of the precoated sand is smoother and has no protruding edges and corners.
(2) Comparative analysis of pore structure
Because the precoated sand has smooth surface and no protruding edges and corners, when the precoated sand is prepared into a water permeable prefabricated part such as a water permeable brick, the pores of the water permeable brick are smooth, the adhesive is biased to be non-polar, the adhesive is not easy to adsorb polar substances, and when pollutant particles are smaller than the pores, the pore interception rate is low, and the blockage is not easy. As shown in the SEM comparison graph of fig. 2, the cement water permeable brick, the ceramic-based water permeable brick, and the coated sand water permeable brick are prepared using the same preparation method and adhesive, fig. 2(a) is the cement-based water permeable brick, fig. 2(b) is the ceramic-based water permeable brick, and fig. 2(c) is the coated sand water permeable brick. The pore of the precoated sand permeable brick is smoother and softer, while the pore of the traditional permeable brick is irregular and has more edges and corners. Angular pores are more likely to be clogged by the particles, thereby reducing the water permeability.
(3) Correlation analysis of silica sand particle size and precoated sand stacking pores
As shown in the table below, the smaller the particle size of the silica sand particles, the smaller the pores, and the smaller the particle size of the entrapable suspended particulate matter.
TABLE 2 silica Sand particle size, pore size and particle size range for entrapping particulate matter
By controlling the particle size of the silica sand particles, the coated sand accumulated pores are controlled, so that the coated sand permeable material can obtain other performances such as pollution resistance and the like. Because the porous material has a larger specific surface area when the pore diameter is small, the material begins to exhibit other functions, such as absorption, adsorption, catalysis (e.g., doping with some components such as photocatalyst, etc.), biological attachment, contact reaction surface, etc. The properties directly increase the anti-pollution property of the precoated sand permeable material (such as basically non-sticky to chewing gum), so that the product can be maintained easily, and the properties of keeping the product permeable and intercepting pollutants can be maintained for a long time.
(4) Analysis of pollutant interception performance of water permeable material
Because the main application scene of the permeable material is to prepare the permeable pavement (including the prefabricated permeable bricks), the following analysis mainly aims at intercepting the runoff pollutants of the pavement, but the water permeability, the pollutant interception and other water permeability performances of the permeable material are communicated in different application scenes, so the analysis is also suitable for other application scenes of the permeable material.
Rainwater falling to the ground contains not only dust in the air and atmospheric pollutants due to the leaching of the atmosphere. When the rain falls to the ground, the ground is washed to form runoff, and the rain runoff on the road surface can take away a large amount of pollutants such as metal, hydrocarbon, rubber, fuel oil and the like which are formed on the road surface due to the abrasion of motor vehicles and have great harm to the environment due to the washing of the road surface on the road. Meanwhile, most pollutants in road traffic accident pollutants, spraying, overflowing, dripping and leaking of toxic and harmful chemicals in road transportation and automobile exhaust gas finally migrate to the water environment under the action of natural sedimentation or rainwater leaching. The road runoff contaminant composition and source are shown in the following table.
TABLE 3 road runoff contamination composition and sources
The main pollutant indexes of the road runoff are SS (in suspended solids, the suspended solids with the particle size of 0.1-1.0 mu m are called finely dispersed suspended solids, and the suspended solids with the particle size of more than 1.0 mu m are called coarsely dispersed suspended solids). For the permeable material, the concentration of the SS has the greatest influence on the water permeability of the permeable brick, and the SS is easily prepared into the required concentration, so that a water sample with a certain SS concentration can be selected as a target water sample for testing.
According to the relevant data, the particle size distribution curve of the four-season road dust sample in Beijing urban area is shown in the figure 3-4, and as can be seen from the figure, the particle size of the four-season road dust sample in Beijing urban area is 52.42-94.40% mainly with the particle size larger than 63 μm, 5.6-47.16% with the particle size of 4-63 μm, and 4.15% with the particle size smaller than 4 μm. According to the distribution of the particle size of the dust on the road in Beijing, kaolin (with stable chemical property and easy dispersion and suspension in water) with the particle size of 100-140 meshes, 140-170 meshes, 170-200 meshes, 200-400 meshes, 400-700 meshes and >700 meshes is adopted to prepare a simulated water sample to carry out a filtration test on the water permeable material.
The maximum daily rainfall in ten years in Beijing is used as the design rainfall, and the catchment area is the upper surface area of the test block: the rainfall intensity was the limiting rainfall intensity, 0.0042m2, 6cm × 7 cm: one decade of rainfall per minute. The water content and solute (kaolin) content of the simulated water samples are shown in table 5.
TABLE 4 Water volume and solute (Kaolin) amount of the simulated Water sample of the prepared Water sample
| Recurrence period (a) | Rainfall deviceVolume (mm) | Water sample volume (L) | Amount of solute (Kaolin) (g) |
| 10 | 201 | 0.8442 | 0.6196 |
A water filtering test of suspensions with different particle sizes of 100-140 meshes, 140-170 meshes, 170-200 meshes, 200-400 meshes, 400-700 meshes and more than 700 meshes is carried out by adopting the coated sand surface layer common concrete base layer composite water permeable brick and the common concrete water permeable brick. The test results are shown in FIGS. 5-6. The average removal rate of the coated sand surface layer common concrete base layer composite water permeable brick on suspensions SS with different particle sizes is generally higher than that of the common concrete water permeable brick, but the removal effect of the common concrete water permeable brick is better within the range of the suspensions with particle sizes of 200-400 meshes. The reason for this may be that suspended particles in this size range are more likely to form a denser filter layer on the surface of the ordinary concrete permeable brick, thereby increasing the removal rate.
(5) Analysis of Water Permeability of Water permeable Material
The porosity of the precoated sand permeable brick is controlled to be 15-35% so as to ensure that the precoated sand permeable brick has good water permeability, including water retention rate, water permeability speed and the like.
The composite brick is prepared, the surface layer is a precoated sand layer, the thickness of the precoated sand layer is about 0.5cm, the porosity is controlled to be about 21.5-22.5%, the base layer is a common concrete layer, and the water permeability performance such as water retention rate weight, water retention rate volume, water permeability rate and the like of the composite brick are tested, so that the requirements of national related water permeable bricks are met, and the performance is excellent as shown in the following table.
TABLE 5 summary of Sand-based Water-permeable Material Properties
Porosity is the pore volume/brick appearance volume
Final water retention-weight-water weight/dry brick weight
Final water retention-volume-water retention volume/brick appearance volume
The invention also provides the application of the permeable material, and the permeable material is used for preparing the permeable prefabricated member or directly paved into a permeable pavement.
Finally, it should be noted that: the above-mentioned embodiments are only used for illustrating the technical solution of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. The permeable material is characterized by comprising silica sand particles, wherein the silica sand particles are uniformly coated with an adhesive to form precoated sand, and the dense stacking pores of the precoated sand particles are smaller than 100 mu m.
2. The water permeable material of claim 1, wherein the coated sand particles have a close packed pore size of less than 85 μm.
3. The water permeable material of claim 1, wherein the coated sand particles have a close-packed particle size pore size of less than 75 μm.
4. The water permeable material of any one of claims 1-3, wherein the coated sand particles have a close-packed particle size of greater than 15 μm.
5. The water permeable material of claim 4, wherein the water permeable material is prepared as a water permeable block having an effective porosity of 15% to 35%.
6. The water permeable material of claim 5, wherein the water permeable material is prepared as a water permeable block having an effective porosity of about 21.5-22.5%.
7. The water permeable material of any one of claims 1-4, wherein the silica sand particles have a particle size in the range of 0.1mm to 1 mm.
8. The water permeable material of any one of claims 1-4, wherein the coated sand particles are calcined at high temperature.
9. The water-permeable material of claim 8, wherein the coated sand particles are calcined at 1000 ℃ for 2-4 hours at 750-.
10. Use of a water-permeable material according to claims 1-9 for the production of water-permeable prefabricated parts or for direct laying as water-permeable road surfaces.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2020106056773 | 2020-06-29 | ||
| CN202010605677 | 2020-06-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112358213A true CN112358213A (en) | 2021-02-12 |
Family
ID=74509077
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011242186.3A Pending CN112358213A (en) | 2020-06-29 | 2020-11-09 | Water permeable material and application thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112358213A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115259745A (en) * | 2022-05-23 | 2022-11-01 | 浙江玖隆新材料科技有限公司 | Manufacturing process and formula of water permeable brick |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100920962B1 (en) * | 2009-04-10 | 2009-10-09 | (주)에프씨코리아랜드 | Seepage paving-material and its paving method using the same in road pavement |
| CN105014007A (en) * | 2015-08-21 | 2015-11-04 | 广东富华铸锻有限公司 | Application method of roughing sand calcination technology to casting and sand core |
| CN105967729A (en) * | 2016-05-17 | 2016-09-28 | 重庆路投科技有限公司 | Novel pavement water-permeable composite material and preparation method thereof |
| CN106587791A (en) * | 2016-08-29 | 2017-04-26 | 中国十七冶集团有限公司 | Superfine iron tailing sand based anti-blocking cement water-permeable mortar pavement |
| CN109592936A (en) * | 2018-11-01 | 2019-04-09 | 仁创生态环保科技股份有限公司 | A kind of inorganic water-permeable brick and its preparation process |
| CN111039595A (en) * | 2018-10-12 | 2020-04-21 | 仁创生态环保科技股份有限公司 | Novel water permeable material and preparation method thereof |
-
2020
- 2020-11-09 CN CN202011242186.3A patent/CN112358213A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100920962B1 (en) * | 2009-04-10 | 2009-10-09 | (주)에프씨코리아랜드 | Seepage paving-material and its paving method using the same in road pavement |
| CN105014007A (en) * | 2015-08-21 | 2015-11-04 | 广东富华铸锻有限公司 | Application method of roughing sand calcination technology to casting and sand core |
| CN105967729A (en) * | 2016-05-17 | 2016-09-28 | 重庆路投科技有限公司 | Novel pavement water-permeable composite material and preparation method thereof |
| CN106587791A (en) * | 2016-08-29 | 2017-04-26 | 中国十七冶集团有限公司 | Superfine iron tailing sand based anti-blocking cement water-permeable mortar pavement |
| CN111039595A (en) * | 2018-10-12 | 2020-04-21 | 仁创生态环保科技股份有限公司 | Novel water permeable material and preparation method thereof |
| CN109592936A (en) * | 2018-11-01 | 2019-04-09 | 仁创生态环保科技股份有限公司 | A kind of inorganic water-permeable brick and its preparation process |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115259745A (en) * | 2022-05-23 | 2022-11-01 | 浙江玖隆新材料科技有限公司 | Manufacturing process and formula of water permeable brick |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8673393B2 (en) | Hydrophobic materials made by vapor deposition coating and applications thereof | |
| Bakr | Diatomite: its characterization, modifications and applications | |
| CN103174076B (en) | A kind of road drainage filter structure | |
| CN113024162A (en) | Red mud modified porous asphalt pavement material and application thereof | |
| WO2021129020A1 (en) | Preparation and construction method of porous coral aggregate permeable purified concrete | |
| CN103572586A (en) | Environment-friendly material capable of purifying air as well as preparation method thereof | |
| CN112250348B (en) | Porous red mud asphalt pavement material for purifying runoff pollutants and preparation and application thereof | |
| CN108889280A (en) | A kind of preparation method of flyash-chitosan composite particle adsorbent material | |
| CN112358213A (en) | Water permeable material and application thereof | |
| CN103172299A (en) | Oil-water separation material and preparation method thereof | |
| CN113230911A (en) | Preparation method of amphiphobic polytetrafluoroethylene membrane | |
| CN113480242B (en) | Geopolymer water permeable brick and preparation method and application thereof | |
| KR101173213B1 (en) | Method for manufacturing functional materials for adsorption of polluant and functional materials manufactured by the same | |
| CN105502827B (en) | Tandem rainwater ecological filters and clean catch device | |
| CN106277673A (en) | Preparation method that deposit Endogenous Phosphorus spatial load forecasting bed mud is material modified and application | |
| CN110683834B (en) | Water permeable brick capable of removing various pollutants and preparation method thereof | |
| CN113105160A (en) | Asphalt pavement material for purifying road runoff pollution and preparation method and application thereof | |
| CN112250358A (en) | Pervious concrete and preparation method thereof | |
| JP2019534774A (en) | Carbon fiber composites, media incorporating carbon fiber composites, and methods related thereto | |
| KR102201653B1 (en) | Eco-friendly system for management of storm water using porous concrete base carrier | |
| CN211713549U (en) | Adsorption water purification type water seepage brick | |
| KR20220046723A (en) | Air purification aggregate coated with zeolite and coconut shell powder activated carbon, method of the same and concrete water permeable block by using the same | |
| CN107829517A (en) | A kind of external wall brick based on blade biomimetic features, its application and lay the dust and subtract haze method | |
| CN111992177B (en) | Non-thermal activation red mud particle adsorbent and preparation method thereof | |
| CN108101416A (en) | A kind of environmentally protective water-permeable brick for purifying air and preparation method thereof |
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 | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210212 |