阅读说明：本技术 一种湿敏变色涂料及其制备方法和应用 (Humidity-sensitive color-changing coating and preparation method and application thereof ) 是由 李贞� 李宏宁 杨超 邓俊杰 谷杭莲 于 2020-12-04 设计创作，主要内容包括：本发明公开了一种湿敏变色涂料,由以下质量份的原料组成：聚乙烯醇：8～10份、甲基纤维素：1～2份、甘油0.2～0.5份、增色剂：3～5份、显色剂：1～3份、蒸馏水：100份。本发明制备的湿敏变色涂料在湿度偏低,湿度适中,湿度偏高的环境中可呈现出明显的颜色变化,反应现象可逆,变色现象明显；在使用时可随意塑形,制成变色膜或变色块；根据不同应用环境确定使用状态,能适应多种使用需求。(The invention discloses a humidity-sensitive color-changing coating which is prepared from the following raw materials in parts by mass: polyvinyl alcohol: 8-10 parts of methyl cellulose: 1-2 parts of glycerol, 0.2-0.5 part of color enhancer: 3-5 parts of color developing agent: 1-3 parts of distilled water: 100 parts. The humidity-sensitive color-changing coating prepared by the invention can show obvious color change in the environment with low humidity, moderate humidity and high humidity, the reaction phenomenon is reversible, and the color change phenomenon is obvious; when in use, the color-changing film or the color-changing block can be made by optionally shaping; the use state is determined according to different application environments, and the method can adapt to various use requirements.)

1. The humidity-sensitive color-changing coating is characterized by comprising the following raw materials in parts by mass: polyvinyl alcohol: 8-10 parts of methyl cellulose: 1-2 parts of glycerol, 0.2-0.5 part of color enhancer: 3-5 parts of color developing agent: 1-3 parts of distilled water: 100 parts.

2. The humidity-sensitive color-changing coating according to claim 1, wherein the humidity-sensitive color-changing coating is composed of the following raw materials in parts by mass: polyvinyl alcohol: 10 parts of methyl cellulose: 1.3 parts, 0.25 part of glycerin, and a color enhancer: 3.3 parts of color developing agent: 2 parts of distilled water: 100 parts.

3. The moisture sensitive color-changing coating of claim 1, wherein the polyvinyl alcohol is type 1799.

4. The moisture-sensitive color-changing coating according to claim 1, wherein the color-developing agent is copper chloride and the color-enhancing agent is potassium chloride.

5. A method for preparing the humidity-sensitive color-changing coating according to any one of claims 1 to 4, comprising the steps of:

s1, weighing raw materials in proportion;

s2, adding polyvinyl alcohol into distilled water, continuously stirring, and heating in a water bath after swelling to obtain a PVA solution;

s3, adding methyl cellulose and glycerol into the PVA solution, stirring until the methyl cellulose and the glycerol are completely dissolved, and standing;

s4, adding the color enhancer and the color developing agent into the standing solution, and uniformly stirring to obtain the humidity-sensitive color-changing coating.

6. The method for preparing the humidity-sensitive color-changing coating according to claim 5, wherein the swelling time in step S2 is 30-45 min.

7. The method for preparing the humidity-sensitive allochroic paint according to claim 5, wherein the water bath heating in the step S2 is carried out at a temperature of 80-100 ℃ for 0.5-1 h.

8. The method for preparing the humidity-sensitive color-changing coating according to claim 5, wherein the stirring speed is 600 to 800 r/min.

9. Use of the moisture-sensitive color-changing coating according to any one of claims 1 to 4 for preparing a moisture-sensitive color-changing film.

10. The use according to claim 9, wherein the use is for preparing a humidity-sensitive color-changing film from a humidity-sensitive color-changing coating by a casting method.

Technical Field

The invention relates to the field of humidity-sensitive color-changing materials, in particular to a humidity-sensitive color-changing coating and a preparation method and application thereof.

Background

With the improvement of living standard and the development of industrial fields such as industry, people have more subtle or delicate requirements in the production and living process, and the requirement on environmental humidity is naturally improved to the level capable of observing, detecting and even changing at any time. The environmental humidity is an important factor affecting the environmental quality, and affects the production and storage of products, for example, the environmental humidity needs to be strictly controlled in the production process and storage of products such as food, electronic components and the like, and whether a humidity sensitive material exists can reflect the humidity of the environment where the product is located on the premise of not damaging the product or packaging becomes more and more important.

The currently commonly used humidity-sensitive white materials mainly comprise humidity-sensitive allochroic silica gel particles, humidity indicator cards and humidity-sensitive allochroic ink; the humidity-sensitive allochroic silica gel particles adsorb water molecules in air by utilizing a microporous structure in the silica gel, so that metal ions such as cobalt ions in the silica gel undergo a complexing reaction to change color, are commonly found in food and medicine packages, and are placed in the packages of food and medicine in a small package mode. The main color-changing substance cobalt chloride used in the humidity-sensitive color-changing silica gel particles is determined as a secondary carcinogen by European Union in 2004, and is not beneficial to human health, the granular silica gel is easy to be eaten by children by mistake, so that accidents are caused, and meanwhile, the test precision is low, and most of the granular silica gel particles are used for determining whether the humidity in the environment exceeds the standard or not and cannot determine the specific humidity range.

The humidity indicator card stores the metal ions such as copper ions and the like which can change color after absorbing moisture by taking paper as a carrier, different circular areas on the paper correspond to a humidity range, and the corresponding areas on the card can change color according to the humidity in the environment after absorbing moisture, so that the humidity in the environment is indicated. The humidity indicator card is applied to containers and other large environments more, is not suitable for food packaging and other small environments, is too single in use form, has the conditions of moving, sliding and the like in the use process, and may have the problems of loss and the like, and the card is made of paper, can deform after meeting liquid water, and has reduced strength, and influences recovery and repeated use.

The humidity-sensitive color-changing ink is characterized in that an acid-base buffer substance is added into a proper conventional coating or ink to adjust the pH value of the coating or ink so as to change the pH value of the coating or ink into an unstable state which is easy to change, and a color developing substance sensitive to pH change is added at the same time, the substance shows different colors under different pH values, the pH value of the ink or coating changes after the ink or coating absorbs water, the color developing substance also changes color, the color changing interval of the existing humidity-sensitive color-changing ink on the market is 5% -65% of the ambient humidity or 40% -80%, and the ink is used in a printing or smearing mode. The application range of the ink is limited by the use mode, the ink is not suitable for all environments due to the fact that various factors such as adaptability to printing materials and the printing mode need to be considered during printing, and the ink has large limitation, and is more used as an anti-counterfeiting coating instead of a humidity monitoring tool in the actual use process.

Disclosure of Invention

The invention aims to provide a humidity-sensitive allochroic paint aiming at the defects in the prior art, which takes polyvinyl alcohol as a main water absorption base material, has small influence on products by the form of the paint after moisture absorption, can effectively absorb water molecules and accurately reflect the water molecule content under the actual environment humidity.

The invention also aims to provide a preparation method of the humidity-sensitive allochroic paint.

The invention also aims to provide the application of the humidity-sensitive color-changing coating in preparing a humidity-sensitive color-changing film.

The purpose of the invention is realized by the following technical scheme:

the humidity-sensitive color-changing coating comprises the following raw materials in parts by mass: polyvinyl alcohol: 8-10 parts of methyl cellulose: 1-2 parts of glycerol, 0.2-0.5 part of color enhancer: 3-5 parts of color developing agent: 1-3 parts of distilled water: 100 parts.

Preferably, the humidity-sensitive color-changing coating comprises the following raw materials in parts by mass: polyvinyl alcohol: 10 parts of methyl cellulose: 1.3 parts, 0.25 part of glycerin, and a color enhancer: 3.3 parts of color developing agent: 2 parts of distilled water: 100 parts.

Further, the polyvinyl alcohol is 1799 in type.

Further, the color developing agent is copper chloride, and the color enhancer is potassium chloride.

The preparation method of the humidity-sensitive allochroic paint comprises the following steps:

s1, weighing raw materials in proportion;

s2, adding polyvinyl alcohol into distilled water, continuously stirring, and heating in a water bath after swelling to obtain a PVA solution;

s3, adding methyl cellulose and glycerol into the PVA solution, stirring until the methyl cellulose and the glycerol are completely dissolved, and standing;

s4, adding the color enhancer and the color developing agent into the standing solution, and uniformly stirring to obtain the humidity-sensitive color-changing coating.

Further, the swelling time in the step S2 is 30-45 min.

Further, the water bath heating in the step S2 is carried out at the temperature of 80-100 ℃ for 0.5-1 h.

Further, the stirring speed is 600-800 r/min.

An application of the humidity-sensitive color-changing coating in preparing a humidity-sensitive color-changing film.

Further, the application is that the humidity-sensitive color-changing coating is prepared into a humidity-sensitive color-changing film by a tape casting method.

Compared with the prior art, the invention has the following beneficial effects:

the humidity-sensitive allochroic paint prepared by the invention is green when the relative humidity is 10-50%, is blue-green when the relative humidity is 50-80%, and is light blue when the relative humidity is 80-95%; the humidity condition in the environment can be reflected through obvious color change, the measurement precision is high, and the color change reaction is reversible.

The water-absorbing base material contains polyvinyl alcohol, methyl cellulose and glycerin, the prepared material is jelly, is in a fluid state before drying, can be shaped at will, and can be used according to different application environments; the moisture-sensitive color-changing film can be prepared by a tape casting method, can be used as a coating, can be directly coated on a bearing object, and can be removed when not used.

The humidity-sensitive allochroic paint prepared by the invention has viscosity, can be fixed at a painting position after being dried, cannot move, can reflect the humidity condition in a product under the condition of not unsealing, and does not occupy space in a package.

Detailed Description

In order to facilitate understanding of the present invention, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the following specific examples.

Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.

Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.

Example 1

The embodiment provides a preparation method of a humidity-sensitive color-changing coating, which comprises the following steps:

s1, weighing the following raw materials in parts by weight: polyvinyl alcohol: 10 parts of methyl cellulose: 1.3 parts, 0.25 part of glycerin, and a color enhancer: 3.3 parts of color developing agent: 2 parts of distilled water: 100 parts of (A);

s2, adding polyvinyl alcohol into distilled water, continuously stirring at the speed of 750r/min, placing the mixture in a water bath kettle at 90 ℃ after swelling for 30min, stopping stirring after 1h, and taking out a beaker from the water bath kettle to obtain a PVA solution;

s3, adding methyl cellulose and glycerol into the PVA solution, stirring for 10min at the rotating speed of 750r/min until the mixture is completely dissolved, and generating a large amount of bubbles in the solution;

s4, standing the solution, adding potassium chloride and copper chloride after bubbles naturally disappear, uniformly stirring to obtain the humidity-sensitive color-changing coating, and pouring the humidity-sensitive color-changing coating into a lightproof storage container for sealed storage.

Example 2

The embodiment provides a preparation method of a humidity-sensitive color-changing coating, which comprises the following steps:

s1, weighing the following raw materials in parts by weight: polyvinyl alcohol: 8 parts of methyl cellulose: 1 part, 0.4 part of glycerin, and a color enhancer: 5 parts of color developing agent: 3 parts of distilled water: 100 parts of (A);

s2, adding polyvinyl alcohol into distilled water, continuously stirring at the speed of 600r/min, placing the mixture into a water bath kettle at the temperature of 100 ℃ after swelling for 45min, stopping stirring after 0.5h, and taking out a beaker from the water bath kettle to obtain a PVA solution;

s3, adding methyl cellulose and glycerol into the PVA solution, stirring for 10min at the rotating speed of 700r/min until the mixture is completely dissolved, and generating a large amount of bubbles in the solution;

s4, standing the solution, adding potassium chloride and copper chloride after bubbles naturally disappear, uniformly stirring to obtain the humidity-sensitive color-changing coating, and pouring the humidity-sensitive color-changing coating into a lightproof storage container for sealed storage.

Example 3

The embodiment provides a preparation method of a humidity-sensitive color-changing coating, which comprises the following steps:

s1, weighing the following raw materials in parts by weight: polyvinyl alcohol: 9 parts of methyl cellulose: 2 parts, 0.2 part of glycerol, and a color enhancer: 5 parts of color developing agent: 1 part of distilled water: 100 parts of (A);

s2, adding polyvinyl alcohol into distilled water, continuously stirring at the speed of 700r/min, placing the mixture into a water bath kettle at the temperature of 80 ℃ after swelling for 40min, stopping stirring after 1h, and taking out a beaker from the water bath kettle to obtain a PVA solution;

s3, adding methyl cellulose and glycerol into the PVA solution, stirring for 10min at the rotating speed of 600r/min until the mixture is completely dissolved, and generating a large amount of bubbles in the solution;

s4, standing the solution, adding potassium chloride and copper chloride after bubbles naturally disappear, uniformly stirring to obtain the humidity-sensitive color-changing coating, and pouring the humidity-sensitive color-changing coating into a lightproof storage container for sealed storage.

Application example 1

The application example provides a humidity-sensitive color-changing film, which is prepared by using the humidity-sensitive color-changing coating in example 1 and forming a film by a tape casting method, and the humidity-sensitive color-changing film is placed in a room with the humidity of 65% and is light green; then transferring the humidity-sensitive color-changing film into a constant humidity box with the humidity of 90 percent, and changing the color of the film into blue; after being taken out from the constant humidity chamber and placed indoors, the film turns into light green.

Application example 2

In the application example, the humidity-sensitive color-changing coating prepared in the embodiment 2 is directly coated inside the vegetable greenhouse, and the greenhouse film is a transparent film, so that the color change condition of the humidity-sensitive color-changing coating can be directly observed outside. When the humidity in the greenhouse is 70%, the humidity-sensitive color-changing coating is blue-green, when the humidity in the greenhouse is reduced to 50%, the humidity-sensitive color-changing coating is green, the humidity in the greenhouse is indicated to be humidified, when the humidity in the greenhouse is increased to 90%, the humidity-sensitive color-changing coating is blue, and at the same time, the haar begins to appear in the greenhouse, the greenhouse is indicated to need ventilation, when the humidity in the greenhouse is reduced to 70%, the humidity-sensitive color-changing coating is changed to blue-green, and the ventilation can be finished.

Application example 3

In the application example, the humidity-sensitive color-changing coating prepared in the embodiment 2 is dried to prepare a blocky humidity-sensitive color-changing block, and the humidity-sensitive color-changing block is respectively placed in glass cabinets with the humidity of 50%, 60% and 90%, so that the humidity-sensitive color-changing block is dark green, and the dark green is changed into blue-green and light blue.

The humidity-sensitive allochroic paint prepared by the invention can determine the use state according to different application environments, and can be prepared into flaky blocks or directly used fluid; the coating can be used as a coating to be directly coated on a bearing object, and can be directly removed when the coating is discarded after being used, so that the use of the product is not influenced. The invention has reversible reaction phenomenon and obvious color change phenomenon, and can adapt to various use requirements.

It should be understood that the above examples are only for clearly illustrating the technical solutions of the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.