阅读说明：本技术 一种铝及铝合金下沉孔阳极氧化前的遮蔽方法 (Shielding method before anodic oxidation of aluminum and aluminum alloy sunken hole ) 是由 张宽 杨彬 于 2019-08-28 设计创作，主要内容包括：本发明公开了一种铝及铝合金下沉孔阳极氧化前的遮蔽方法,所述方法是先对下沉孔待遮蔽区域依次进行脱脂、碱洗、一次水洗、酸洗、二次水洗及干燥,之后对下沉孔底面及侧壁打磨,然后在下沉孔底面上贴胶带,最后在涂抹密封防腐蚀胶,即完成遮蔽。本发明通过固体胶加液体胶双重密封,解决下沉孔的遮蔽问题,在水、酸、碱等液体中浸泡24小时均不会产生脱落,20MPa高压水枪冲洗10min也不会产生脱落,不仅保证了阳极质量,且返修率也降为0,大大提高了产品生产效率。(The invention discloses a shielding method before anodic oxidation of aluminum and aluminum alloy sunken holes, which comprises the steps of sequentially degreasing, alkali washing, primary water washing, acid washing, secondary water washing and drying a to-be-shielded area of a lower sunken hole, polishing the bottom surface and the side wall of the lower sunken hole, then pasting an adhesive tape on the bottom surface of the lower sunken hole, and finally smearing a sealing anti-corrosion adhesive to finish shielding. The invention solves the problem of shielding the lower counter bore by double sealing of solid glue and liquid glue, does not fall off after being soaked in water, acid, alkali and other liquids for 24 hours, does not fall off after being washed by a high-pressure water gun with the pressure of 20MPa for 10min, not only ensures the anode quality, but also reduces the repair rate to 0, and greatly improves the production efficiency of products.)

1. A shielding method before anodic oxidation of aluminum and aluminum alloy sunken holes is characterized in that firstly, degreasing, alkali washing, primary water washing, acid washing, secondary water washing and drying are sequentially carried out on to-be-shielded areas of lower sunken holes, then the bottom surfaces and the side walls of the sunken holes are polished, adhesive tapes are pasted on the bottom surfaces of the lower sunken holes, and finally, sealing anti-corrosion glue is smeared, so that shielding is finished.

2. The method for shielding the aluminum and aluminum alloy lower counter bore before anodic oxidation as recited in claim 1, wherein the degreasing is performed by using a degreasing agent solution with the temperature of 58-60 ℃ and the mass fraction of 3-4% for cleaning for 1-5 min.

3. The method for shielding the aluminum and aluminum alloy lower counter bore before anodic oxidation as recited in claim 1, wherein the alkaline washing is carried out for 5-10min by adopting a sodium hydroxide solution with the temperature of 20-40 ℃ and the mass fraction of 0.5-2%.

4. The method for shielding the aluminum and aluminum alloy lower counter bore before anodic oxidation as recited in claim 1, wherein the acid washing is performed by neutralization for 5-10min by using a nitric acid solution with the temperature of 34-36 ℃ and the mass fraction of 15-30%.

5. The method for masking the aluminum or aluminum alloy lower counterbore before anodizing as recited in claim 1, wherein the polishing is performed by manually polishing the bottom surface and the sidewall of the lower counterbore to be smooth and without protruding points with waterproof abrasive paper.

6. The method as claimed in claim 5, wherein the polishing further comprises purging impurities in the abrasive powder by compressed air, and then polishing the bottom surface and the side wall of the lower counterbore by sponge sand paper absorbing absolute ethanol.

7. The method for masking the aluminum or aluminum alloy lower counterbore before anodizing as recited in claim 6, further comprising scrubbing the bottom surface and the sidewalls of the lower counterbore after sanding with sponge sand paper with a clean cloth for absorbing absolute ethanol.

8. The method for shielding the aluminum and aluminum alloy counterbores before anodic oxidation as recited in claim 1, wherein the distance from the four sides of the adhesive tape to the side walls of the counterbores is 1-2mm, and a hot air gun is used for blowing the surface of the adhesive tape when the adhesive tape is attached, and a scraper is used for scraping the attached surface.

9. The method for shielding the aluminum and aluminum alloy lower counter bore before anodic oxidation according to claim 1, wherein the anti-corrosion sealant comprises the following components in percentage by weight: 18-22% of naphtha, 55-65% of toluene, 15-20% of talcum powder and 2-4% of chrome yellow.

10. The method for shielding the aluminum and aluminum alloy lower counter bore before anodic oxidation according to claim 1, wherein the method for applying the anti-corrosion sealant comprises the steps of firstly pouring the sealant to the middle part of the bottom surface of the lower counter bore, then using the tip of the bamboo stick to apply the sealant flowing to the edge part of the bottom surface of the lower counter bore, cutting off the sealant at the periphery of the bottom surface of the lower counter bore after drying, and then using the tip of the bamboo stick to dip the anti-corrosion sealant to apply the anti-corrosion sealant to the periphery for sealing.

Technical Field

The invention belongs to the technical field of shielding of aluminum and aluminum alloy products, and particularly relates to a shielding method before anodic oxidation of aluminum and aluminum alloy sunken holes.

Background

In order to overcome the defects of surface hardness, wear resistance and the like of the aluminum alloy and prolong the service life, a surface treatment technology is an indispensable ring in the use of the aluminum alloy, and an anodic oxidation technology is the most widely applied and successful at present. Under the action of corresponding electrolyte and specific technological conditions and the action of applied current, aluminium and its alloy can form an oxide film on the aluminium product, i.e. the product must be soaked in specific solution for a certain period of time.

The CVD related products are aluminum and aluminum alloy products at present, not all areas need to be subjected to anode in the production and regeneration processes, some areas need to be electrified and are shielded before the anode, a sunken hole exists in one product, the bottom of the product does not need to be plated with an anode film, but the periphery of the product needs to be plated with the anode film, the traditional method is difficult to process, the currently shielded areas are soaked in water or electrolyte for a long time and then washed by a high-pressure water gun with the pressure of 20MPa, the holes are easy to fall off, the hole walls are directly sealed by some holes, the anode films cannot be generated on the hole walls, the repair rate of the holes is 100%, and the quality and the production efficiency of the product anode are.

Disclosure of Invention

The invention aims to solve the technical problems in the prior art. Therefore, the invention provides a shielding method for aluminum and aluminum alloy sunken holes before anodic oxidation, and aims to facilitate shielding of the bottoms of the sunken holes.

In order to achieve the purpose, the invention adopts the technical scheme that:

a shielding method before anodic oxidation of aluminum and aluminum alloy sunken holes comprises the steps of sequentially carrying out degreasing, alkali washing, primary water washing, acid washing, secondary water washing and drying on to-be-shielded areas of lower sunken holes, polishing the bottom surfaces and the side walls of the sunken holes, then pasting adhesive tapes on the bottom surfaces of the lower sunken holes, and finally smearing sealing anti-corrosion adhesives to finish shielding.

The degreasing is carried out for 1-5min by adopting a degreasing agent solution with the temperature of 58-60 ℃ and the mass fraction of 3-4%.

The alkaline washing is carried out by stripping for 5-10min by adopting sodium hydroxide solution with the temperature of 20-40 ℃ and the mass fraction of 0.5-2%.

The acid washing is carried out for neutralization for 5-10min by adopting nitric acid solution with the temperature of 34-36 ℃ and the mass fraction of 15-30%.

And the polishing is to manually polish the bottom surface and the side wall of the lower counter bore to be smooth and without convex points by adopting waterproof abrasive paper.

And the polishing also comprises the steps of blowing the impurities of the grinding powder through compressed air, and then polishing the bottom surface and the side wall of the lower counter bore by adopting sponge sand paper absorbing absolute ethyl alcohol.

The method also comprises the step of scrubbing the bottom surface and the side wall of the sinking hole polished by the sponge abrasive paper by using clean cloth absorbing absolute ethyl alcohol.

The distance from the four edges of the adhesive tape to the side wall of the lower counter bore is 1-2mm, a hot air gun is adopted to blow the surface of the adhesive tape when the adhesive tape is pasted, and a scraper blade is used for scraping the pasting surface.

The anti-corrosion sealant comprises the following components in percentage by weight: 18-22% of naphtha, 55-65% of toluene, 15-20% of talcum powder and 2-4% of chrome yellow.

The method for coating the anti-corrosion sealant comprises the steps of firstly removing the sealant and pouring the sealant to the middle part of the bottom surface of the sunken hole, then coating the sealant which flows to the edge part of the bottom surface of the sunken hole flatly by using the tip of the bamboo stick, drying the sealant, cutting off the sealant on the periphery of the bottom surface of the sunken hole, and then coating the periphery with the anti-corrosion sealant by dipping the tip of the bamboo stick.

The invention has the beneficial effects that: the invention solves the problem of shielding the lower counter bore by double sealing of solid glue and liquid glue, does not fall off after being soaked in water, acid, alkali and other liquids for 24 hours, does not fall off after being washed by a high-pressure water gun with the pressure of 20MPa for 10min, not only ensures the anode quality, but also reduces the repair rate to 0, and greatly improves the production efficiency of products.

Drawings

The description includes the following figures, the contents shown are respectively:

fig. 1 is a schematic structural view of the present invention.

Labeled as:

1. a lower counter bore, 2, an adhesive tape, 3, an anti-corrosion sealant, 4, a cut-off and then sealed area.

Detailed Description

The following detailed description of the embodiments of the present invention will be given with reference to the accompanying drawings for a purpose of helping those skilled in the art to more fully, accurately and deeply understand the concept and technical solution of the present invention and to facilitate its implementation.

As shown in figure 1, the shielding method before anodic oxidation of the aluminum and aluminum alloy sunken hole comprises the steps of sequentially degreasing, alkali washing, primary water washing, acid washing, secondary water washing and drying the to-be-shielded area of the lower sunken hole 1 of a product, polishing the bottom surface and the side wall of the sunken hole, then pasting an adhesive tape 2 on the bottom surface of the lower sunken hole, and finally smearing a sealing anti-corrosion adhesive 3 to finish shielding.

Preferably, degreasing is carried out for 1-5min by adopting a degreasing agent solution with the temperature of 58-60 ℃ and the mass fraction of 3-4%. The main components of the degreasing agent are sodium tetraborate and pentasodium triphosphate, wherein the mass percent of the sodium tetraborate is 70-80%, and the mass percent of the pentasodium triphosphate is 1-10%. The alkali washing is carried out by stripping for 5-10min by using sodium hydroxide solution with the mass fraction of 0.5-2% and the temperature of 20-40 ℃. The acid washing is carried out by neutralizing for 5-10min by nitric acid solution with the temperature of 34-36 ℃ and the mass fraction of 15-30%. And the polishing is to manually polish the bottom surface and the side wall of the lower counter bore to be smooth and without convex points by adopting waterproof abrasive paper. And blowing the impurities of the grinding powder by compressed air, and then polishing the bottom surface and the side wall of the lower counter bore by sponge abrasive paper absorbing absolute ethyl alcohol.

Furthermore, the shielding method also comprises the step of scrubbing the bottom surface and the side wall of the sinking hole polished by the sponge abrasive paper by using clean cloth absorbing absolute ethyl alcohol.

The distance from the four edges of the adhesive tape to the side wall of the sunken hole is 1-2mm, a hot air gun is adopted to blow the surface of the adhesive tape when the adhesive tape is pasted, and a scraper blade is used for scraping the pasting surface.

The anti-corrosion sealant comprises the following components in percentage by weight: 18-22% of naphtha, 55-65% of toluene, 15-20% of talcum powder and 2-4% of chrome yellow. Preferably, the anti-corrosion sealant comprises the following components in percentage by weight: 20% of naphtha, 60% of toluene, 17% of talcum powder and 3% of chrome yellow, and the method for coating the anti-corrosion sealant comprises the steps of firstly removing the sealant, pouring the sealant to the middle part of the bottom surface of the sunken hole, then coating the sealant which flows to the edge part of the bottom surface of the sunken hole by using the tip of the bamboo stick, cutting the sealant around the bottom surface of the sunken hole after drying, and then coating the periphery with the anti-corrosion sealant by dipping the tip of the bamboo stick again. The method aims to further increase the firmness of bonding and avoid the phenomenon of edge tilting. Specific examples are as follows:

example 1

A shielding method before anodic oxidation of aluminum and aluminum alloy sunken holes comprises the following steps:

firstly, cleaning a region to be shielded (a bottom surface region of a lower counter bore) for 3min by using a degreasing agent (wherein the mass percent of sodium tetraborate is 75%, and the mass percent of pentasodium triphosphate is 10%) with the concentration (mass fraction) of 3.5% and the temperature of 60 ℃.

Secondly, the cleaned area is stripped for 8min by using a sodium hydroxide solution with the concentration (mass fraction) of 1.2% and the temperature of 30 ℃, and then cleaned by using pure water.

And thirdly, neutralizing the stripped area for 8min by using a nitric acid solution with the concentration (mass fraction) of 22% and the temperature of 35 ℃, cleaning by using pure water after neutralization, and finally drying by using compressed air.

And fourthly, within 30min after blow-drying, manually polishing the bottom surface and the side wall of the lower counter bore by using waterproof abrasive paper 180# and 240# until the bottom surface and the side wall are smooth and have no salient points, and blowing the impurities of the grinding powder by using compressed air.

Fifthly, adding absolute ethyl alcohol (with the MOS grade concentration of 99.7%) into No. 600 sponge sand paper to polish the bottom surface and the side wall.

Sixthly, adding absolute ethyl alcohol into the clean cloth to scrub the bottom surface and the side wall;

seventhly, cutting a PET high-temperature-resistant green adhesive tape, pasting the PET high-temperature-resistant green adhesive tape to the bottom surface of the sinking hole, wherein the size of the four sides of the green adhesive tape is slightly smaller (1-2) mm than the size of the bottom surface of the sinking hole, blowing the surface of the adhesive tape by using a hot air gun (60 ℃) while scraping the surface by using a scraper blade during pasting, and repeating three times; the high temperature resistant glue is a whole block, the middle part of the glue is not spliced, and the edge part of the glue does not have burrs or cracks.

And eighthly, coating liquid sealing anti-corrosion glue (20% of naphtha, 60% of toluene, 17% of talcum powder and 3% of chrome yellow), pouring the sealing anti-corrosion glue into the middle of the sinking hole, allowing the sealing anti-corrosion glue to automatically flow to all positions of the bottom surface of the sinking hole, troweling the sealing anti-corrosion glue at the edge part by using a bamboo stick tip, not coating the sealing anti-corrosion glue on the side wall, and naturally drying for 10min after coating.

And ninthly, after air drying, slightly cutting the periphery of the sealed anticorrosive adhesive layer by using a carving knife, wherein the cut area is the position above the left of the dotted line in the figure.

And tenthly, cutting off redundant parts, dipping a small amount of sealing anti-corrosion glue on the top of the bamboo stick to coat the periphery of the bottom surface of the sinking hole once, naturally drying for 10min, and then putting the sinking hole into a water tank containing water, acid or alkali and the like to clean the anode.

Example 2

A shielding method before anodic oxidation of aluminum and aluminum alloy sunken holes comprises the following steps:

firstly, cleaning a region to be shielded (a bottom surface region of a lower counter bore) for 3min by using a degreasing agent (wherein the mass percent of sodium tetraborate is 75%, and the mass percent of pentasodium triphosphate is 10%) with the concentration (mass fraction) of 3.5% and the temperature of 60 ℃.

Secondly, the cleaned area is stripped for 8min by using a sodium hydroxide solution with the concentration (mass fraction) of 1.2% and the temperature of 30 ℃, and then cleaned by using pure water.

And thirdly, neutralizing the stripped area for 8min by using a nitric acid solution with the concentration (mass fraction) of 22% and the temperature of 35 ℃, cleaning by using pure water after neutralization, and finally drying by using compressed air.

And fourthly, within 30min after blow-drying, manually polishing the bottom surface and the side wall of the lower counter bore by using waterproof abrasive paper 180# and 240# until the bottom surface and the side wall are smooth and have no salient points, and blowing the impurities of the grinding powder by using compressed air.

Fifthly, adding absolute ethyl alcohol (with the MOS grade concentration of 99.7%) into No. 600 sponge sand paper to polish the bottom surface and the side wall.

Sixthly, adding absolute ethyl alcohol into the clean cloth to scrub the bottom surface and the side wall;

seventhly, cutting a PET high-temperature-resistant green adhesive tape, pasting the PET high-temperature-resistant green adhesive tape to the bottom surface of the sinking hole, wherein the size of the four sides of the green adhesive tape is slightly smaller (1-2) mm than the size of the bottom surface of the sinking hole, blowing the surface of the adhesive tape by using a hot air gun (60 ℃) while scraping the surface by using a scraper blade during pasting, and repeating three times; the high temperature resistant glue is a whole block, the middle part of the glue is not spliced, and the edge part of the glue does not have burrs or cracks.

And eighthly, coating liquid sealing anti-corrosion glue (20% of naphtha, 60% of toluene, 17% of talcum powder and 3% of chrome yellow), pouring the sealing anti-corrosion glue into the middle of the sinking hole, allowing the sealing anti-corrosion glue to automatically flow to all positions of the bottom surface of the sinking hole, troweling the sealing anti-corrosion glue at the edge part by using a bamboo stick tip, not coating the sealing anti-corrosion glue on the side wall, and naturally drying for 10min after coating.

Example 3

A shielding method before anodic oxidation of aluminum and aluminum alloy sunken holes comprises the following steps:

firstly, cleaning a region to be shielded (a bottom surface region of a lower counter bore) for 3min by using a degreasing agent (wherein the mass percent of sodium tetraborate is 75%, and the mass percent of pentasodium triphosphate is 10%) with the concentration (mass fraction) of 3.5% and the temperature of 60 ℃.

Secondly, the cleaned area is stripped for 8min by using a sodium hydroxide solution with the concentration (mass fraction) of 1.2% and the temperature of 30 ℃, and then cleaned by using pure water.

And thirdly, neutralizing the stripped area for 8min by using a nitric acid solution with the concentration (mass fraction) of 22% and the temperature of 35 ℃, cleaning by using pure water after neutralization, and finally drying by using compressed air.

And fourthly, within 30min after blow-drying, manually polishing the bottom surface and the side wall of the lower counter bore by using waterproof abrasive paper 180# and 240# until the bottom surface and the side wall are smooth and have no salient points, and blowing the impurities of the grinding powder by using compressed air.

Fifthly, adding absolute ethyl alcohol into the clean cloth to scrub the bottom surface and the side wall;

sixthly, cutting a PET high-temperature-resistant green adhesive tape, pasting the PET high-temperature-resistant green adhesive tape to the bottom surface of the sinking hole, wherein the size of the four sides of the green adhesive tape is slightly smaller (1-2) mm than the size of the bottom surface of the sinking hole, blowing the surface of the adhesive tape by using a hot air gun (60 ℃) while scraping the surface by using a scraper blade, and repeating three times; the high temperature resistant glue is a whole block, the middle part of the glue is not spliced, and the edge part of the glue does not have burrs or cracks.

And seventhly, coating liquid sealing anti-corrosion glue (20% of naphtha, 60% of toluene, 17% of talcum powder and 3% of chrome yellow), pouring the sealing anti-corrosion glue into the middle of the sinking hole, allowing the sealing anti-corrosion glue to automatically flow to all positions of the bottom surface of the sinking hole, troweling the edges by using bamboo stick tips without coating the edges to the side walls, and naturally drying for 10min after coating.

Eighthly, after air drying, slightly cutting the periphery of the sealed anticorrosion glue layer by using a carving knife, wherein the cut area is the position above the left of the dotted line in the figure.

And ninthly, cutting off redundant parts, dipping a small amount of sealing anti-corrosion glue on the tip of the bamboo stick to coat the periphery of the bottom surface of the sinking hole once, naturally drying for 10min, and then putting the sinking hole into a water tank containing water, acid or alkali and the like to clean the anode.

Example 4

A shielding method before anodic oxidation of aluminum and aluminum alloy sunken holes comprises the following steps:

firstly, cleaning a region to be shielded (a bottom surface region of a lower counter bore) for 3min by using a degreasing agent (wherein the mass percent of sodium tetraborate is 75%, and the mass percent of pentasodium triphosphate is 10%) with the concentration (mass fraction) of 3.5% and the temperature of 60 ℃.

Secondly, the cleaned area is stripped for 8min by using a sodium hydroxide solution with the concentration (mass fraction) of 1.2% and the temperature of 30 ℃, and then cleaned by using pure water.

And thirdly, neutralizing the stripped area for 8min by using a nitric acid solution with the concentration (mass fraction) of 22% and the temperature of 35 ℃, cleaning by using pure water after neutralization, and finally drying by using compressed air.

And fourthly, within 30min after blow-drying, manually polishing the bottom surface and the side wall of the lower counter bore by using waterproof abrasive paper 180# and 240# until the bottom surface and the side wall are smooth and have no salient points, and blowing the impurities of the grinding powder by using compressed air.

Fifthly, adding absolute ethyl alcohol into the clean cloth to scrub the bottom surface and the side wall;

sixthly, cutting a PET high-temperature-resistant green adhesive tape, pasting the PET high-temperature-resistant green adhesive tape to the bottom surface of the sinking hole, wherein the size of the four sides of the green adhesive tape is slightly smaller (1-2) mm than the size of the bottom surface of the sinking hole, blowing the surface of the adhesive tape by using a hot air gun (60 ℃) while scraping the surface by using a scraper blade, and repeating three times; the high temperature resistant glue is a whole block, the middle part of the glue is not spliced, and the edge part of the glue does not have burrs or cracks.

And seventhly, coating liquid sealing anti-corrosion glue (20% of naphtha, 60% of toluene, 17% of talcum powder and 3% of chrome yellow), pouring the sealing anti-corrosion glue into the middle of the sinking hole, allowing the sealing anti-corrosion glue to automatically flow to all positions of the bottom surface of the sinking hole, troweling the edges by using bamboo stick tips without coating the edges to the side walls, and naturally drying for 10min after coating.

Example 5

A shielding method before anodic oxidation of aluminum and aluminum alloy sunken holes comprises the following steps:

firstly, cleaning a region to be shielded (a bottom surface region of a lower counter bore) for 3min by using a degreasing agent (wherein the mass percent of sodium tetraborate is 78%, and the mass percent of pentasodium triphosphate is 8%) with the concentration (mass fraction) of 4% and the temperature of 60 ℃.

Secondly, the cleaned area is stripped for 8min by using a sodium hydroxide solution with the concentration (mass fraction) of 2% and the temperature of 40 ℃, and then cleaned by using pure water.

And thirdly, neutralizing the stripped area for 10min by using a nitric acid solution with the concentration (mass fraction) of 28% and the temperature of 35 ℃, cleaning by using pure water after neutralization, and finally drying by using compressed air.

And fourthly, within 30min after blow-drying, manually polishing the bottom surface and the side wall of the lower counter bore by using waterproof abrasive paper 180# and 240# until the bottom surface and the side wall are smooth and have no salient points, and blowing the impurities of the grinding powder by using compressed air.

Fifthly, adding absolute ethyl alcohol (with the MOS grade concentration of 99.7%) into No. 600 sponge sand paper to polish the bottom surface and the side wall.

Sixthly, adding absolute ethyl alcohol into the clean cloth to scrub the bottom surface and the side wall;

seventhly, cutting a PET high-temperature-resistant green adhesive tape, pasting the PET high-temperature-resistant green adhesive tape to the bottom surface of the sinking hole, wherein the size of the four sides of the green adhesive tape is slightly smaller (1-2) mm than the size of the bottom surface of the sinking hole, blowing the surface of the adhesive tape by using a hot air gun (60 ℃) while scraping the surface by using a scraper blade during pasting, and repeating three times; the high temperature resistant glue is a whole block, the middle part of the glue is not spliced, and the edge part of the glue does not have burrs or cracks.

And eighthly, coating liquid sealing anti-corrosion glue (20% of naphtha, 60% of toluene, 17% of talcum powder and 3% of chrome yellow), pouring the sealing anti-corrosion glue into the middle of the sinking hole, allowing the sealing anti-corrosion glue to automatically flow to all positions of the bottom surface of the sinking hole, troweling the sealing anti-corrosion glue at the edge part by using a bamboo stick tip, not coating the sealing anti-corrosion glue on the side wall, and naturally drying for 10min after coating.

And ninthly, after air drying, slightly cutting the periphery of the sealed anticorrosive adhesive layer by using a carving knife, wherein the cut area is the position above the left of the dotted line in the figure.

And tenthly, cutting off redundant parts, dipping a small amount of sealing anti-corrosion glue on the top of the bamboo stick to coat the periphery of the bottom surface of the sinking hole once, naturally drying for 10min, and then putting the sinking hole into a water tank containing water, acid or alkali and the like to clean the anode.

The test on the sinking hole shielded by the five embodiments shows that the sinking holes in the embodiments 1 and 5 can not fall off after being soaked in water, acid, alkali and other liquids for 24 hours, and can not fall off after being washed by a high-pressure water gun with the pressure of 20MPa for 10min, and the phenomenon that the side of the sinking hole is tilted can not occur; in the embodiment 2 and the embodiment 4, the phenomenon that the side of the sinking hole is partially tilted appears; examples 3 and 4 showed local exfoliation after washing with a 20MPa high pressure water gun for 7 minutes.

The invention is described above with reference to the accompanying drawings. It is to be understood that the specific implementations of the invention are not limited in this respect. Various insubstantial improvements are made by adopting the method conception and the technical scheme of the invention; the present invention is not limited to the above embodiments, and can be modified in various ways.