CN110804350B

CN110804350B - Acid-encountering color-changing warning coating and preparation method thereof

Info

Publication number: CN110804350B
Application number: CN201911254751.5A
Authority: CN
Inventors: 冯圣玉; 吴连锋; 王贤明; 卢海峰
Original assignee: Shandong University
Current assignee: Shandong University
Priority date: 2019-12-08
Filing date: 2019-12-08
Publication date: 2021-08-31
Anticipated expiration: 2039-12-08
Also published as: CN110804350A

Abstract

The invention relates to an acid-encountering color-changing warning coating and a preparation method thereof, wherein the acid-encountering color-changing warning coating comprises the following components in parts by mass: 50-100 parts of strong acid resistant resin, 1-30 parts of special color-changing agent A, 0.5-5 parts of auxiliary color-changing component, 0-20 parts of filler, 0-20 parts of auxiliary agent and 0-300 parts of solvent. The acid-encountering warning coating is strong in acid, obvious in color change, rapid in color change and reversible in color change. The acid-encountering warning coating prepared by taking the single-component strong acid-resistant resin as the matrix resin and adding the special color-changing agent A, the auxiliary color-changing component, the pigment filler and the like has the characteristics of obvious color change, quick color change, reversible color change, good matching property and the like. Suitable for the manufacture, storage, transportation and use of strong acid surfaces. The method has good market demand prospect in manufacturing industries such as petroleum alkylation, fluorine chemical industry, ore flotation, paper pulp and papermaking industry, semiconductor industry and the like.

Description

Acid-encountering color-changing warning coating and preparation method thereof

Technical Field

The invention relates to an acid-encountering color-changing warning coating, and belongs to the field of comprehensive utilization of chemical products.

Background

Strong acids such as concentrated sulfuric acid, hydrofluoric acid, nitric acid, hydrochloric acid and the like are widely applied to chemical production such as petroleum alkylation, fluorine chemical industry, ore flotation, paper pulp and paper making industry, semiconductor industry and the like, and make great contribution to promoting national economy development. At present, two traditional alkylation processes in the petrochemical industry are respectively a hydrofluoric acid process and a sulfuric acid process.

The sulfuric acid method is a process for synthesizing industrial isooctane (namely alkylate) from isobutane and butene by using sulfuric acid as a catalyst. The prepared alkylate is a mixture of isoparaffin, has good antiknock property and lead-free gasoline octane number of more than 94, has ideal volatility and clean combustion performance, and is an ideal component of the motor gasoline. The main problems of the sulfuric acid process are high acid consumption, 70-80kg of sulfuric acid is needed for producing 1t of alkylate oil, and a large amount of dilute acid is produced as a byproduct. The positions of the alkylation device, such as the flange connection position of the sulfuric acid conveying pipeline, are potential leakage points, and once leakage occurs, huge harm can be brought. Therefore, it is important to detect the acid leakage as early as possible, and the damage caused by the acid leakage can be greatly reduced.

The warning paint changing color when encountering acid is a special paint for detecting whether acid liquor leaks or not. The color-changing paint is coated on a flange or a valve of an acid liquor conveying pipeline, plays a role in corrosion resistance under normal conditions, can generate obvious color change in a short time once leakage occurs, has quick and lasting color change, can play an effective warning role, is convenient for timely treating the leakage part, and prevents major safety accidents.

Similar to sulfuric acid, industrial acids such as phosphoric acid and perchloric acid have the serious problems of easy leakage, no color, high harmfulness and the like in the processes of storage, transportation and use, once leakage occurs, great harm is brought, and warning coating aiming at acid liquor is urgently needed.

Chinese patent document CN106905833A (application No. 201710218911.5) provides an environment-friendly color-changing interior wall coating and a preparation method thereof. The coating comprises a polyurethane resin material, ethanol, an anti-shrinking agent, a triphenylmethane dye or a fluoran dye. The paint can effectively warn the peracid or over-alkali environment which is unfavorable for human health, so that people can timely keep the air circulation of the working environment, and take active protective measures. However, the polyurethane resin selected is not resistant to strong acid, and the coating can be decomposed and fall off when the strong acid leaks, so that the equipment cannot be protected.

Chinese patent document CN108530053A (application number: 201810279464.9) discloses a pH value sensitive color-changing inorganic material and a preparation method thereof, and the pH value sensitive color-changing coating or film material can be obtained by mixing the prepared pH value sensitive color-changing powder with other resin solution or emulsion. The prepared pH value sensitive color-changing inorganic material has more steps and higher energy consumption in the preparation process.

Chinese patent document CN106820356A discloses a PVC glove which changes color when encountering acid and a preparation method thereof. An inner sleeve layer, a middle layer and an outer sleeve layer are sequentially arranged from inside to outside; wherein the inner sleeve layer is a polyurethane layer, the middle layer is a PVC glove body layer, and the outer sleeve layer is an acid color-changing coating. The acid color-changing coating adopts acid color-changing liquid which comprises the following components in parts by weight: 0.5-5 parts of an acid indicator; 35-70 parts of water; 10-25 parts of ethanol; 10-25 parts of methyl ethyl ketone. However, this patent document uses methyl orange, an acid indicator that is readily soluble in water. Methyl orange is easily dissolved in water during actual use, thereby losing the color change effect.

U.S. patent document US5489331A discloses a multiple coloring composition comprising (a) a base color aqueous coloring composition containing a base color dye whose coloring ability is deteriorated in the presence of an acid; and (b) a hyperchromic aqueous coloring composition comprising a colorant capable of retaining its characteristic color in the presence of a pH of about 4 or less; and an acid sufficient to provide a pH of the hyperchromic composition of about 4 or less. The coloring composition adopts a plurality of materials for proportioning to realize the coloring effect, and has complex formula and poor controllability.

Although the research on the acid-encountering warning coating is early, the acid-encountering warning coating is successfully developed by only a few companies, and is widely applied to petrochemical devices, fluorine chemical industries, semiconductor industries and the like. Because the development difficulty is high, the research on the domestic acid warning coating is less. In the last 90 years, China developed a 'hydrogen fluoride indicating paint', but compared with foreign products, the hydrogen fluoride indicating paint has the problems of unobvious color change, long color change time, irreversible color change (only disposable use) and the like, and the application is greatly limited. At present, the acid warning coating used in China basically depends on import and has the problems of high price, long supply period and the like.

In summary, there is an urgent need in the industry for a warning paint that changes color rapidly, has low cost, and can be reused when encountering acids, especially for colorless and less volatile strong acids such as sulfuric acid, phosphoric acid, perchloric acid, etc.

Disclosure of Invention

Aiming at the defects of the existing acid warning coating technology at home and abroad, the invention provides a warning coating aiming at strong acid with small volatility, such as sulfuric acid, phosphoric acid, perchloric acid and the like, and the coating has the advantages of simple formula, easy preparation and convenient industrial production. The coating has the characteristics of rapid color change, obvious color change and reversible color change, can be matched with various coatings such as epoxy, acrylic acid, polyurethane and the like for use, is widely applied to the positions of pipeline flange joints, storage tank seals and the like in devices in the petrochemical industry, detects whether strong acid with small volatility such as sulfuric acid leaks or not, and plays a role in timely alarming.

Summary of The Invention

The warning coating for the strong acid with low volatility provided by the invention is prepared by taking a strong acid resistant resin as a film forming substance and adding a special color changing agent, an auxiliary color changing component, a filler, an auxiliary agent and the like. After the mixture is coated, the color change is obvious and rapid, the quick warning effect can be achieved, the color change is reversible (the initial state can be restored by water washing), and the mixture can be used repeatedly; the coating can be matched with most coatings such as epoxy, acrylic acid, polyurethane and the like, and has wide application range.

Detailed Description

The technical scheme of the invention is as follows:

the acid-encountering color-changing warning coating comprises the following components in parts by mass:

50-100 parts of strong acid resistant resin, 1-30 parts of special color-changing agent A, 0.5-5 parts of auxiliary color-changing component, 0-20 parts of filler, 0-20 parts of auxiliary agent and 0-300 parts of solvent;

the special color-changing agent A has the following structural characteristics:

wherein: r' is various organic groups playing a role of bridging, and a benzene ring is connected with a silicon atom; further preferably an alkylene group, more preferably an alkylene group of C1-C8, preferably a methylene group, an ethylene group or a propylene group;

r 'is a variety of organic groups capable of leaving in the HOR' structure; further preferred is an alkyl group or an aryl group, more preferred is an alkyl group or a phenyl group having from C1 to C8, and preferred is a methyl group, an ethyl group, an isopropyl group, a tert-butyl group or a phenyl group.

According to the present invention, it is preferable that the strong acid resistant resin includes various strong acid resistant resins; further preferably alkyd resin, chlorinated rubber resin, high chlorinated polyethylene resin, epoxy resin, polyurethane resin, acrylic resin, silicone resin and fluorocarbon resin; fluorocarbon resins are more preferred.

According to the invention, preferably, the special color-changing agent A is prepared by the following method:

selecting a compound with a structure on the left of an R' group in a molecule of the special color-changing agent, and carrying out a chemical modification process to enable the compound to have reaction activity, so that the activated compound reacts with silane to obtain the special color-changing agent A.

According to the present invention, preferred compounds of the structure to the left of the R' group in the specialty color changing agent molecule include, but are not limited to: methyl orange and methyl orange derivatives.

According to the present invention, the above chemical modification processes preferably include, but are not limited to: acyl chloride, epoxy functionalization, hydroxyl functionalization, carboxyl functionalization and the like.

According to the present invention, the silane includes, but is not limited to, various commercially available silane coupling agents and small molecule silane compounds, including aminopropyltrimethoxysilane, aminopropyltriethoxysilane, chloropropyltriethoxysilane, chloropropyltrimethoxysilane, trimethylmonochlorosilane, dimethyldichlorosilane, methyltrichlorosilane, tetrachlorosilane, dimethylmonohydrochlorosilane, and the like.

According to the invention, a preparation process which is not directly described for the above process, but which makes it possible to obtain the specific color-changing agent A from commercially available products, is also within the scope of the invention.

According to the invention, preferably, the auxiliary color-changing component comprises various components capable of improving the color brightness of the coating and assisting the special color-changing agent A to perform color-changing display, including various organic dyes and inorganic pigments; further preferably modified polyaniline, medium chrome yellow, permanent yellow, lemon yellow, titanium nickel yellow and sun-proof yellow; more preferably a mixture of the modified polyaniline, the medium chrome yellow and the permanent yellow.

According to the invention, preferably, the filler is used for improving basic performances such as mechanical property and the like of the coating, and comprises titanium dioxide, mica powder, aluminum hydroxide, magnesium hydroxide, silica micropowder, white carbon black, talcum powder, nano calcium carbonate and barium sulfate; further preferred is a mixture of titanium dioxide, mica powder and aluminum hydroxide.

According to the invention, the auxiliary agent is preferably various agents capable of improving the performance of the coating, including a leveling agent, a defoaming agent, a dispersing agent and an anti-settling agent; further preferred are mixtures of leveling agents and defoamers.

According to the present invention, the solvent is preferably selected according to the kind of resin, and is a variety of solvents capable of achieving good mixing of the coating mixture; including dimethyl carbonate, toluene, xylene, ethylene glycol monomethyl ether, ethanol, propylene glycol methyl ether acetate, acetone, butyl acetate, ethyl acetate, etc.; butyl acetate is more preferable.

According to the invention, the mass ratio of the strong acid resistant resin, the special color-changing agent A, the auxiliary color-changing component, the filler, the auxiliary agent and the solvent is preferably 100: 1-30: 0.5-5: 0-20: 0-20: 0 to 300; more preferably 100: 5-20: 1-5: 5-20: 5-10: 50-200.

According to the invention, preferably, the acid-exposure color-change warning coating further comprises 25 parts by mass of a curing agent; more preferably, the curing agent is an isocyanate curing agent or a polyamide resin.

According to the invention, the preparation method of the acid-encountering color-changing warning coating comprises the following steps:

mixing the strong acid resistant resin, the special color-changing agent A, the auxiliary color-changing component, the filler, the auxiliary agent and the solvent according to the weight ratio, stirring and dispersing uniformly, and then grinding until the fineness is less than 40 micrometers to obtain the coating A component.

According to the invention, preferably, the curing agent is used as the component B of the coating, and the component A of the coating and the component B of the coating are mixed according to the proportion of 4-5: 1 mass ratio, and obtaining the acid-encountering color-changing coating.

The invention is not described in detail in the prior art.

The principle and the beneficial effects of the invention are as follows:

the function of the acid-discoloring warning coating is to timely discolor to play a role in warning and alarming when acid leaks from the flange, and a paint film is kept complete and does not change except the discoloring phenomenon so as to prevent the corrosion of a base material, so that the coating is required to have strong acid resistance.

The principle of the invention is that the gas-sensitive paint for volatile acid is prepared by utilizing the performance of the special color-changing agent A changing color when meeting acid, strengthening the color change through the auxiliary color-changing component and combining the reasonable compatibility of the filler, the auxiliary agent and the solvent.

The special color-changing agent A can interact with strong acid liquid to change color. The general commercial acid-base indicator can also realize the purpose of acid discoloration. However, after the commercially available acid-base indicator is processed into a coating, the indicator is easily faded and lost when meeting water, and even the coating is easily degraded and falls off. The special color-changing agent A is insoluble in water and sensitive in color change after the silicon-containing part reacts with the resin, so that the special color-changing agent A is superior to a commercially available acid-base indicator.

The auxiliary color-changing component can improve the color brightness of the coating and assist the special color-changing agent A to change color and display. The special color-changing agent A disclosed by the invention is lighter in color in a normal state and shows deep red after encountering strong acid. In order to improve the color warning effect of the color-changing agent A, the color tone of the coating before encountering acid is changed into bright yellow by selecting the mixture of the modified polyaniline, the medium chrome yellow and the permanent yellow. The paint is bright yellow before encountering acid and deep red after encountering acid. The color change effect of the special color changing agent A can be improved by selecting pigment components with other colors. But from the practical factory application, the mixing proportion effect of the modified polyaniline, the medium chrome yellow and the permanent yellow is the best.

The filler can improve the basic performances of mechanical property and the like of the coating. For example, mica powder can reinforce and improve the hardness of the coating; the aluminum hydroxide can reinforce and improve the flame retardance of the coating; titanium dioxide can reinforce and improve weather resistance, white carbon black can reinforce and improve the hydrophobicity of the surface of the coating, and the like. The filler is screened according to different application requirements of the coating. In view of the current plant application, a mixture of titanium dioxide, mica powder and aluminum hydroxide is preferred.

The auxiliary agent provided by the invention is various auxiliary agents capable of improving the performance of the coating. For example, the leveling agent is beneficial to forming a film on the surface of the equipment by the coating; the defoaming agent can eliminate the internal foaming of the coating, improve the density of the coating and reduce the defects; the dispersant can realize good dispersion of various inorganic fillers and prevent agglomeration, and the anti-settling agent can keep various inorganic fillers to realize uniform dispersion in a coating system, does not settle and generates hard blocks which can not be stirred up.

The solvent of the invention is various solvents which can realize good mixing of the coating mixture, and the solvents are selected according to different types of matrix resins of the coating. For example, toluene is suitable for nitrolacquers, air-drying vinyl paints; ethyl acetate is suitable for nitrolacquer; butyl acetate is suitable for nitrolacquer, polyurethane lacquer, acrylic acid lacquer and the like; acetone is suitable for ethylene copolymers and nitrocellulose coatings; the ethanol is suitable for occasions with higher requirements on environmental protection, and the propylene glycol monomethyl ether and the propylene glycol methyl ether acetate are suitable for high-end occasions. Butyl acetate is preferred in view of the use conditions of the chemical plant.

The invention has the beneficial effects that:

the invention provides an acid-encountering warning coating which is strong in acid, obvious in color change, rapid in color change and reversible in color change. The acid-encountering warning coating prepared by taking the single-component strong acid-resistant resin as matrix resin and adding the special color-changing agent A, the auxiliary color-changing component, the pigment and the filler has the following characteristics:

1. the color change is obvious. The yellow color changes into red color when encountering acid.

2. The color change is rapid. The color change time is less than 1S.

3. The color change is reversible. The color can be restored by washing with water after changing color, and the color can be used repeatedly.

4. The matching performance is good.

And a more remarkable effect is achieved. The paint developed by the invention has wide application field, and is suitable for acidic liquid with pH less than 3, including liquid hydrofluoric acid, phosphoric acid, sulfuric acid, fluosilicic acid, hydrochloric acid, nitric acid, chlorine, hydrobromic acid, trifluoroacetic acid, perchloric acid, glacial acetic acid, other acids or acid vapor.

Suitable for the manufacture, storage, transportation and use of strong acid surfaces.

The method has good market demand prospect in manufacturing industries such as petroleum alkylation, fluorine chemical industry, ore flotation, paper pulp and papermaking industry, semiconductor industry and the like.

Drawings

FIG. 1 shows an IR spectrum of a specialty color-changing agent A1 obtained in example 1.

FIG. 2 is a graph showing the color change of the test film in the sulfuric acid solution in test example 1.

FIG. 3 is a graph showing the color change of the test film in the sulfuric acid, perchloric acid, phosphoric acid solution in Experimental example 1.

FIG. 4 is a graph showing the color change of the test film after color change in test example 3 after water immersion to remove surface sulfuric acid.

FIG. 5 is a graph comparing the performance of the present invention in test example 4 with that of foreign products.

Detailed Description

The present invention is further illustrated by, but is not limited to, the following specific examples.

The starting materials used in the examples are either conventional commercially available starting materials or are synthesized according to the literature methods.

The molecular weights described in the examples are all number average molecular weights. The parts described in the examples are parts by weight.

BYK410 and BYK180 used in the embodiment are anti-settling aids, which can keep various inorganic fillers to be uniformly dispersed in a coating system, do not settle, generate hard blocks which cannot be stirred up, and are commercially available products.

Example 1

The preparation of the special color-changing agent A1 comprises the following steps:

20g of methyl orange was added to 100mL of anhydrous tetrahydrofuran solution under argon protection, followed by dropwise addition of 20mL of diformyl chloride and reaction for 2 hours at room temperature with stirring. After the solvent was distilled off, 100mL of an anhydrous tetrahydrofuran solution was added again to the reaction system, followed by addition of excess aminopropyltriethoxysilane and stirring at room temperature for 3 hours. The solvent was distilled off and then unreacted aminopropyltriethoxysilane was distilled off under reduced pressure to give a functionalized methyl orange compound with siloxy groups. Is marked as special color-changing agent A1.

The reaction scheme is as follows:

the special color-changing agent A1 is analyzed and characterized, and an infrared spectrum is shown in figure 1.

Example 2

Weighing 80 parts of fluorocarbon resin, 3 parts of titanium dioxide, 10 parts of mica powder, 3 parts of aluminum hydroxide, 3 parts of modified polyaniline and 15 parts of a color-changing agent A1; 1 part of medium chrome yellow, 1 part of permanent yellow, 6 parts of BYK410, 4 parts of BYK180 and 50 parts of butyl acetate are preliminarily mixed, a high-speed dispersion machine is used for stirring and dispersing for 30 minutes, then the coating is transferred to a basket type sand mill, and when the fineness is less than 40 micrometers, the coating is discharged and packaged to be a coating A component, a coating B component is 20 parts of isocyanate curing agent N3375, and A, B components are 4: 1 to obtain the acid-encountering color-changing coating.

Example 3

Weighing 80 parts of fluorocarbon resin, 5 parts of white carbon black, 8 parts of talcum powder, 3 parts of magnesium hydroxide, 5 parts of modified polyaniline and 12 parts of color-changing agent A1; 1 part of lemon yellow, 1 part of titanium-nickel yellow, 5 parts of BYK410, 5 parts of BYK180 and 50 parts of dimethylbenzene are preliminarily mixed, a high-speed dispersion machine is used for stirring and dispersing for 30 minutes, then the coating is transferred to a basket type sand mill, and when the fineness is less than 40 micrometers, the coating is discharged and packaged to be a coating A component, a coating B component is 20 parts of isocyanate curing agent N3375, and A, B components are mixed according to the proportion of 4: 1 to obtain the acid-encountering color-changing coating.

Example 4

Weighing 80 parts of fluorocarbon resin, 4 parts of titanium dioxide, 7 parts of mica powder, 3 parts of aluminum hydroxide, 2 parts of modified polyaniline and 20 parts of a color-changing agent A1; 0.5 part of medium chrome yellow, 1.5 parts of permanent yellow, 3 parts of BYK410, 7 parts of BYK180 and 100 parts of dimethylbenzene are preliminarily mixed, a high-speed dispersion machine is used for stirring and dispersing for 30 minutes, then the coating is transferred to a basket type sand mill, and when the coating is ground to the fineness of less than 40 micrometers, the coating A is discharged and packaged, the coating B is 20 parts of isocyanate curing agent N3375, and the A, B is prepared according to the following steps of 4: 1 to obtain the acid-encountering color-changing coating.

Example 5

Weighing 100 parts of alkyd resin, 4 parts of titanium dioxide, 6 parts of mica powder, 4 parts of aluminum hydroxide, 4 parts of modified polyaniline and 30 parts of a color-changing agent A1; 1 part of medium chrome yellow, 1 part of permanent yellow, 5 parts of BYK410, 5 parts of BYK180 and 50 parts of toluene are preliminarily mixed, stirred and dispersed for 30 minutes by using a high-speed dispersion machine, then the coating is transferred to a basket type sand mill, ground until the fineness is less than 40 microns, discharged and packaged.

Example 6

Weighing 60 parts of E51 epoxy resin, 3 parts of mica powder, 6 parts of nano calcium carbonate, 5 parts of barium sulfate, 3 parts of modified polyaniline and 15 parts of a color-changing agent A2; 1.5 parts of medium chrome yellow, 0.5 part of permanent yellow, 5 parts of BYK410, 5 parts of BYK180 and 100 parts of dimethylbenzene are preliminarily mixed, a high-speed dispersion machine is used for stirring and dispersing for 30 minutes, then the coating is transferred to a basket type sand mill, and when the coating is ground to the fineness of less than 40 micrometers, the coating A is discharged and packaged, the coating B is 40 parts of polyamide 300# resin, and the A, B is prepared according to the following steps of: 1 to obtain the acid-encountering color-changing coating.

Example 7

Weighing 85 parts of polyurethane resin, 3 parts of titanium dioxide, 8 parts of mica powder, 3 parts of aluminum hydroxide, 4 parts of modified polyaniline and 15 parts of a color-changing agent A2; 1 part of lemon yellow, 1 part of titanium-nickel yellow, 7 parts of BYK410, 3 parts of BYK180 and 50 parts of butyl acetate are preliminarily mixed, a high-speed dispersion machine is used for stirring and dispersing for 30 minutes, then the coating is transferred to a basket type sand mill, and when the fineness is less than 40 micrometers, the coating is discharged and packaged to be a coating A component, a coating B component is 15 parts of isocyanate curing agent N3390, and A, B components are mixed according to the proportion of 4: 1 to obtain the acid-encountering color-changing coating.

Example 8

Weighing 100 parts of acrylic resin, 5 parts of titanium dioxide, 6 parts of mica powder, 3 parts of aluminum hydroxide, 3 parts of modified polyaniline and 20 parts of a color-changing agent A2; 1 part of medium chrome yellow, 1 part of permanent yellow, 3 parts of BYK410, 7 parts of BYK180 and 100 parts of dimethylbenzene are preliminarily mixed, stirred and dispersed for 30 minutes by using a high-speed dispersion machine, then the coating is transferred to a basket type sand mill, ground until the fineness is less than 40 microns, discharged and packaged.

Example 9

Weighing 100 parts of organic silicon modified acrylic resin, 3 parts of titanium dioxide, 8 parts of white carbon black, 3 parts of silicon micropowder, 4 parts of modified polyaniline and 15 parts of color-changing agent A3; 1.5 parts of medium chrome yellow, 0.5 part of permanent yellow, 5 parts of BYK410, 5 parts of BYK180 and 100 parts of ethyl acetate are preliminarily mixed, stirred and dispersed for 30 minutes by using a high-speed dispersion machine, then the coating is transferred to a basket type sand mill, ground until the fineness is less than 40 microns, discharged and packaged.

Example 10

Weighing 100 parts of chlorinated rubber resin, 6 parts of titanium dioxide, 4 parts of mica powder, 4 parts of aluminum hydroxide, 3 parts of modified polyaniline and 20 parts of a color-changing agent A3; 0.5 part of medium chrome yellow, 1.5 parts of permanent yellow, 4 parts of BYK410, 6 parts of BYK180 and 100 parts of dimethylbenzene are preliminarily mixed, stirred and dispersed for 30 minutes by using a high-speed dispersion machine, then the coating is transferred to a basket type sand mill, ground until the fineness is less than 40 microns, discharged and packaged.

Example 11

Weighing 100 parts of high chlorinated polyethylene resin, 3 parts of titanium dioxide, 8 parts of mica powder, 3 parts of aluminum hydroxide, 4 parts of modified polyaniline and 15 parts of color-changing agent A3; primarily mixing 1 part of lemon yellow, 1 part of permanent yellow, 6 parts of BYK410, 4 parts of BYK180 and 50 parts of toluene, stirring and dispersing for 30 minutes by using a high-speed dispersion machine, then transferring the coating to a basket type sand mill, grinding until the fineness is less than 40 micrometers, discharging and packaging.

Test example 1

Spraying or brushing the resin on a polytetrafluoroethylene sheet, and curing for 7 days at room temperature to form a film with the thickness of 1.5 +/-0.5 mm. The tensile strength of the coatings in the above examples was tested and the results are shown in table 1.

TABLE 1

Numbering	Tensile strength of paint film (MPa)	Elongation at Break (%)
			Example 2	15.1	7
Example 3	16.0	5
			Example 4	19.5	9
Example 5	10.2	5
			Example 6	19.8	2
Example 7	21.2	8
			Example 8	11.7	10
Example 9	7.2	10
			Example 10	9.0	21
Example 11	8.7	10

As can be seen from Table 1, after the color-changing agent A is added, the tensile strength and the elongation at break of the coating are both high, and the use requirements are met.

The resin tensile strength test piece was immersed in a sulfuric acid solution, and the color change was shown in fig. 2. As can be seen from fig. 2, the yellow color of the test film turned red, and the color change was significant.

The color change of the test film in sulfuric acid, perchloric acid and phosphoric acid is shown in fig. 3, and it can be seen from fig. 3 that the test film changes from yellow to red in the above acids, and the color change is obvious.

Test example 2

The color change performance of the coating in the above examples in the presence of strong acid sulfuric acid was tested, and the color change time and color change of the coating in different examples are shown in Table 2.

TABLE 2

As can be seen from Table 2, the acid discoloration warning coating of the present invention rapidly changes color after encountering acid, and the color change reaction can occur within 1s at the fastest speed. And the color change is changed from yellow to red, the color change is obvious before and after, and the color is easy to perceive and plays a role in warning.

Test example 3

The reversible property of the paint in the above examples was tested, and the color change was observed after the sulfuric acid was removed from the surface of the discolored paint by soaking in water. The results are shown in FIG. 4.

As can be seen from fig. 4, after the sulfuric acid on the surface of the discolored coating is removed by soaking in water, the color of the coating is changed from red to yellow. Tests prove that the coating which is recovered to be yellow turns red after meeting sulfuric acid, which shows that the color change of the coating has reversibility and can be repeatedly used for more than 10 times. The paint color change of the invention has good reversibility.

Test example 4

The performance of the coating of the present invention was tested against commercially available foreign and domestic products, and the results are shown in table 3 and fig. 5. In fig. 5, the No. 1 is a warning coating changing color when encountering liquid hydrofluoric acid abroad, and the No. 2 is a warning coating changing color when encountering liquid hydrofluoric acid according to the invention.

TABLE 3

Index (I)	Foreign product	The product	Other products in China
				Degree of color change	Yellow → red	Yellow → red	Orange yellow → yellow
Time of color change	＜1s	＜1s	＞1h
				Whether or not it is reversible	Is that	Is that	Whether or not

As can be seen from the table 3 and the figure 5, the performance of the acid-encountering warning coating is superior to that of domestic similar products. Compared with foreign products, the color change time and the reversibility are similar, but the color change of the coating is more obvious and brilliant. And the preparation cost of the invention is obviously lower than that of foreign products. For example: the price of foreign products is about 600-. Therefore, the acid-encountering color-changing coating provided by the invention has the advantages of excellent performance and low cost, reduces the production period and breaks through the foreign technical monopoly.

Claims

1. The acid-encountering color-changing warning coating is characterized by comprising the following components in parts by mass:

wherein: r' is various alkylene groups with the function of bridging, and a benzene ring is connected with a silicon atom;

r 'is a variety of alkyl or phenyl groups capable of leaving in the HOR' structure.

2. The paint as claimed in claim 1, wherein the strong acid resistant resin is alkyd resin, chlorinated rubber resin, high chlorinated polyethylene resin, epoxy resin, polyurethane resin, acrylic resin, silicone resin or fluorocarbon resin.

3. The acid-encountering color change warning coating as claimed in claim 1, wherein the auxiliary color change component is modified polyaniline, medium chrome yellow, permanent yellow, lemon yellow, titanium nickel yellow or sun-proof yellow;

the filler is titanium dioxide, mica powder, aluminum hydroxide, magnesium hydroxide, silicon micropowder, white carbon black, talcum powder, nano calcium carbonate or barium sulfate;

the auxiliary agent is a flatting agent, a defoaming agent, a dispersing agent or an anti-settling agent;

the solvent is dimethyl carbonate, toluene, xylene, ethylene glycol monomethyl ether, ethanol, propylene glycol methyl ether acetate, acetone, butyl acetate or ethyl acetate.

4. The paint for warning color change when encountering acid as claimed in claim 1, wherein the mass ratio of the strong acid-resistant resin, the special color-changing agent A, the auxiliary color-changing component, the filler, the auxiliary agent and the solvent is 100: 1-30: 0.5-5: 0-20: 0-20: 0-300.

5. The paint for warning color change when encountering acid as claimed in claim 4, wherein the mass ratio of the strong acid-resistant resin, the special color-changing agent A, the auxiliary color-changing component, the filler, the auxiliary agent and the solvent is 100: 5-20: 1-5: 5-20: 5-10: 50-200.

6. The acid-discoloring warning paint as claimed in claim 1, further comprising 25 parts by mass of a curing agent.

7. The acid-discoloring warning paint as claimed in claim 6, wherein the curing agent is an isocyanate curing agent or a polyamide resin.

8. The method for preparing the acid-discoloring warning paint as claimed in claim 6, which comprises the following steps:

mixing strong acid resistant resin, a special color-changing agent A, an auxiliary color-changing component, a filler, an auxiliary agent and a solvent according to a weight ratio, stirring and dispersing uniformly, and then grinding until the fineness is less than 40 micrometers to obtain a coating A component;

taking a curing agent as a coating B component, and mixing the coating A component and the coating B component according to the weight ratio of 4-5: 1 mass ratio, and obtaining the warning coating which changes color when meeting acid.

9. A special color-changing agent A meeting acid is characterized by having the following structural characteristics:

r 'is a variety of alkyl or aryl groups capable of leaving in the HOR' structure.

10. The method for preparing special color-changing agent A meeting acid as claimed in claim 9, comprising the following steps:

selecting a compound with a structure at the left side of an R' group in a molecule of the special acid-encountering discoloring agent, and carrying out a chemical modification process to enable the compound to have reaction activity, so that the activated compound reacts with silane to obtain the special acid-encountering discoloring agent A.

11. The method for preparing the special color-changing agent A meeting the acid according to claim 10, wherein the compound of the structure left of the R' group in the molecule of the special color-changing agent meeting the acid is methyl orange or a methyl orange derivative;

the chemical modification process is acyl chlorination, epoxy functionalization, hydroxyl functionalization or carboxyl functionalization reaction;

the silane is aminopropyl trimethoxy silane, aminopropyl triethoxy silane, chloropropyl trimethoxy silane, trimethyl monochlorosilane, dimethyl dichlorosilane, methyl trichlorosilane, tetrachlorosilane or dimethyl monohydro monochlorosilane.