Color-changing ink and preparation method thereof, color-changing label and mineral water packaging

Abstract

The present invention discloses a color-changing ink, a preparation method thereof, a color-changing label, and mineral water packaging. The color-changing ink is measured in parts by mass, and the raw materials for preparing the color-changing ink include the following components: 20 to 50 parts of a film-forming resin, 30 to 90 parts of a solvent, 1 to 3 parts of a pH regulator, and 0.5 to 6 parts of a developer, wherein the developer is ninhydrin. The color-changing ink includes a developer that undergoes a condensation color change reaction with oil and sweat secreted by the human body. When the color-changing ink is printed and dried, a touch color-changing area is formed. Touching the touch color-changing area with a finger forms a specific blue-purple fingerprint pattern within the touch color-changing area, thereby providing identification and preventing confusion of items. The preparation method of the color-changing ink is used to prepare the color-changing ink, the color-changing label includes a touch color-changing area, and the touch color-changing area is obtained by printing the color-changing ink. The mineral water packaging includes a color-changing label, and the color-changing label is the color-changing label.

Description

Technical Field

[0001] The present invention relates to the technical field of inks, and in particular to a color-changing ink and a preparation method thereof, a color-changing label and mineral water packaging. Background Art

[0002] In some public places attended by many people, such as conference rooms, organizers often give each person a bottle of mineral water of the same brand and exactly the same packaging. During the use of the mineral water, it is often placed too close to the mineral water of the neighboring seat, and ultimately it is impossible to distinguish which bottle is yours after the intermission. For the sake of hygiene, people often have to discard the unused mineral water, resulting in huge waste.

[0003] The utility model patent with publication number CN201566973U discloses a beverage bottle that can be marked. The bottle body of the beverage bottle is provided with a label, and the label is provided with a scratch-off layer. Users can scratch out a specific pattern on the scratch-off layer to distinguish mineral water packaging. However, this technical solution has a defect, that is, when using fingernails to scratch the pattern on the scratch-off layer, debris will be generated. These debris will remain in the nail crevices and are difficult to clean, which will cause people to have a bad sense of smell.

[0004] Therefore, it is necessary to provide a color-changing ink and a preparation method thereof, a color-changing label and a mineral water package to solve the above problems. Summary of the Invention

[0005] A first aspect of the present invention provides a color-changing ink.

[0006] A color-changing ink, wherein the raw materials for preparing the color-changing ink include the following components, measured in parts by mass:

[0007] 20 to 50 parts of film-forming resin;

[0008] 30 to 90 parts of solvent;

[0009] 1 to 3 parts pH regulator; and

[0010] 0.5 to 6 parts of developer;

[0011] Wherein, the color developer is ninhydrin.

[0012] In one embodiment, the molecular weight of the film-forming resin is 40,000 to 150,000.

[0013] In one embodiment, the film-forming resin is selected from at least one of waterborne polyacrylate resin, waterborne polyurethane resin and polyvinyl pyrrolidone.

[0014] In one embodiment, the pH adjuster is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, acetic acid and citric acid.

[0015] In one embodiment, 1 to 3 parts of adsorption material are further included.

[0016] In one embodiment, the adsorption material is selected from at least one of white carbon black, zeolite powder and microsilica powder.

[0017] In one embodiment, 0.1 to 1 part of a hygroscopic material is further included.

[0018] The above-mentioned color-changing ink contains a color developer, which can undergo a condensation color change reaction with the oil and sweat components secreted by the human body. When the above-mentioned color-changing ink is printed and dried, a touch color-changing area is formed. By touching the touch color-changing area with a finger, a specific blue-purple fingerprint pattern is formed in the touch color-changing area, thereby playing an identification role and preventing confusion of objects.

[0019] A second aspect of the present invention provides a method for preparing a color-changing ink.

[0020] A method for preparing a color-changing ink, for preparing any one of the color-changing inks provided in the first aspect of the present invention, comprising the following steps:

[0021] Add 20 to 50 parts of a film-forming resin to 30 to 90 parts of a solvent and stir thoroughly to obtain a first solution;

[0022] Add 1 to 3 parts of a pH regulator to the first solution and stir thoroughly to obtain a second solution;

[0023] 0.5 to 6 parts of a color developer are added to the second solution and stirred thoroughly to obtain a color-changing ink.

[0024] A third aspect of the present invention provides a color-changing label.

[0025] A color-changing label comprises a laminated base layer and a color-changing layer, wherein the color-changing layer is printed with any one of the color-changing inks provided in the first aspect of the present invention.

[0026] The fourth aspect of the present invention also provides a mineral water package.

[0027] A mineral water package comprises a bottle and a color-changing label, wherein the color-changing label is the color-changing label provided in the third aspect of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flowchart of a method for preparing a color-changing ink according to one embodiment;

[0029] Figure 2 A flowchart of a method for preparing a color-changing ink according to another embodiment;

[0030] Figure 3 This is a schematic diagram of the color-changing label structure according to one embodiment;

[0031] Figure 4 For example Figure 3 A schematic diagram of the color-changing label after color change;

[0032] Figure 5 Schematic diagram of the color-changing label structure in another embodiment;

[0033] Figure 6 For example Figure 5 Schematic diagram of the color-changing label shown before color change;

[0034] Figure 7 For example Figure 5 Schematic diagram of the color-changing label shown after color change;

[0035] Figure 8 For example Figure 7 A partial enlarged schematic diagram of the color-changing label shown;

[0036] Figure 9 Schematic diagram of mineral water packaging according to one embodiment. DETAILED DESCRIPTION

[0037] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0038] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected" or "communicating" with another element, it may be directly connected to the other element or there may be an intermediate element. The terms "upper," "lower," "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0039] The following is a further detailed description of the color-changing ink, color-changing label and mineral water packaging mainly in conjunction with the accompanying drawings and specific embodiments.

[0040] The color-changing ink of one embodiment is prepared from raw materials comprising the following components, measured in parts by mass:

[0041] 20 to 50 parts of a film-forming resin, 30 to 90 parts of a solvent, 1 to 3 parts of a pH regulator, and 0.5 to 6 parts of a developer, wherein the developer is ninhydrin.

[0042] The film-forming resin has a mass fraction of 20 to 50 parts. The film-forming resin is used to make the color-changing ink have the characteristics of drying and forming a film, so that the color-changing ink can adhere to the surface of the substrate.

[0043] In this embodiment, the film-forming resin is a water-based film-forming resin, which can be dissolved in solvent water, has good environmental performance, and can significantly reduce the emission of pollutants such as VOCs.

[0044] Optionally, the molecular weight of the water-based film-forming resin is 40,000 to 150,000. By limiting the molecular weight of the water-based film-forming resin, the color-changing ink can have better adhesion, friction resistance and flexibility after being cured into a film.

[0045] Preferably, the molecular weight of the aqueous film-forming resin is 60,000 to 120,000. After the aqueous film-forming resin with a molecular weight within this range is formed into a film, the adhesion, friction resistance and flexibility are in a relatively balanced range.

[0046] Optionally, the aqueous film-forming resin is selected from at least one of aqueous polyacrylate resin, aqueous polyurethane resin and polyvinyl pyrrolidone.

[0047] It should be understood that other materials that are soluble in solvents and have film-forming properties after drying can also be used as the film-forming resin of the present invention.

[0048] The solvent has a mass fraction of 30 to 90 parts, and is used to dissolve the film-forming resin, the pH regulator, and the developer, so that the color-changing ink is in a colloidal state, thereby making the color-changing ink printable.

[0049] In this embodiment, the solvent is dehydrated.

[0050] It should be understood that other liquids that can dissolve the film-forming resin, pH adjuster and developer can also be used as the solvent of the present invention.

[0051] The color developer has a mass fraction of 0.5 to 6 parts. The color developer can undergo a condensation color change reaction with the oil and sweat components secreted by the human body, so that after the human body comes into contact with the color-changing ink, the color-changing ink can undergo a visual color change, thereby being perceived by the human eye.

[0052] The oil and sweat secreted by the human body contain rich ingredients such as water, protein, triglycerides, fatty acids, phospholipids, inositol, lipidated cholesterol and amino acids. One or more of the above substances can undergo condensation color change reaction with the color developer, thereby changing the color of the color-changing ink.

[0053] In this embodiment, the color change reaction is an amino acid indicating reaction, and the color developing agent is ninhydrin.

[0054] Ninhydrin, also known as hydrated ninhydrin, can sublime at high temperatures. Ninhydrin can react with substances such as amino acids and proteins in human body oils or sweat to produce bluish-purple Roman purple. Specifically, the color change reaction mechanism of ninhydrin and amino acids is as follows:

[0055] First, ninhydrin is dehydrated and condensed with amino groups to give the first imine:

[0056]

[0057] Secondly, the first imine is isomerized to another form of the second imine after decarboxylation:

[0058]

[0059] Again, the second imine hydrolyzes to release one molecule of aldehyde and one molecule of primary amine:

[0060]

[0061] Finally, the primary amine further undergoes a condensation reaction with ninhydrin to obtain a purple dimerized imine derivative - Roman purple:

[0062]

[0063] The unique color-developing properties of ninhydrin make it an important application in the detection of amine compounds, especially amino acids. Its condensation color change reaction with amino acids is called the ninhydrin reaction. This reaction is very sensitive. At a specific wavelength, the depth of the blue-purple color generated can be used to perform colorimetric determination of the amino acid content in the sample. Therefore, in criminal investigation cases, ninhydrin is often used for fingerprint extraction.

[0064] In another embodiment, the color change reaction is a pH indicator reaction, and the color developer is a pH indicator.

[0065] The color of the pH indicator changes with the pH of the environment. Because human oils and sweat contain acidic substances such as triglycerides, fatty acids, phospholipids, and amino acids, their pH is acidic. Therefore, when the human body comes into contact with the color-shifting ink, some of the oils and sweat components are transferred to the surface of the ink, causing the pH value of the ink surface to change, which in turn causes the color of the ink to change.

[0066] Optionally, pH indicators include, but are not limited to, phenol red, bromothymol blue, bromocresol green, bromocresol purple, m-cresol purple, cresol red, bromophenol blue, methyl orange, methyl red, alizarin, thymolphthalein, and anthocyanin.

[0067] The pH value regulator has a mass fraction of 1 to 3 parts. The pH value regulator is used to adjust the pH value of the color-changing ink so that the pH value of the color-changing ink is maintained in the weakly acidic range of 4-7. Since the oils, amino acids and other substances secreted by the human body are weakly acidic in themselves, the amino groups, carboxyl groups and other groups participating in the condensation color change reaction of the weakly acidic amino acids have strong activity in the weakly acidic environment. At the same time, the acidic ink environment can make the hydroxyl group of ninhydrin have a strong reaction ability, thereby ensuring that the human secretions can undergo a relatively rapid condensation color change reaction with the color developer.

[0068] Experiments have shown that the pH value of ink has a huge impact on the condensation color change reaction of ninhydrin and amino acids:

[0069] When the pH value of the color-changing ink is less than 4, in a strongly acidic environment, although the strongly acidic environment can enhance the reactivity of the hydroxyl group of ninhydrin, it will inhibit the activity of amino groups, carboxyl groups and other groups in weakly acidic amino acids that participate in the condensation color-changing reaction, thereby greatly reducing the rate of the condensation color-changing reaction; at the same time, the product Roman purple obtained by the condensation color-changing reaction is also unstable in a strongly acidic environment and easily fades. The fading can be restored by neutralizing it with alkali.

[0070] When the pH value of the color-changing ink is kept in the weak acid range of 4-7, it has the following three beneficial effects: (1) In a weak acid environment, both the groups involved in the condensation color change reaction in ninhydrin and amino acids have strong activity, which makes the condensation color change reaction of amino acids and ninhydrin more efficient. After the human body touches the ink surface, the color-changing ink can show obvious color changes within five minutes at room temperature. The faster condensation color change reaction efficiency makes the color-changing ink more practical. (2) The weak acid environment can also reduce the interference of groups other than amino groups on the condensation color change reaction, avoiding the color-changing ink from giving false indications before use. (3) In a weak acid environment, the Roman purple generated by the condensation color change reaction is more stable and can remain colorfast for a long time.

[0071] Preferably, the pH value of the color-changing ink is maintained at 5-6. Under this pH value environment, the condensation color-changing reaction of amino acids and ninhydrin is most efficient. After the human body touches the surface of the ink, an obvious color change can occur within two minutes at room temperature, and the resulting Roman purple color is the most stable.

[0072] When the pH value of the color-changing ink is greater than 7, the reactivity of the hydroxyl group of ninhydrin is inhibited, and the rate of the condensation color-changing reaction is greatly slowed down. The condensation color-changing reaction often needs to be heated to 50-70°C to proceed, and the colored condensation product obtained has a certain reducing property. After the heating is stopped, the colored condensation product is easily oxidized by oxygen in the air, causing color changes or even fading. Therefore, the practicality is poor.

[0073] When the pH value of the color-changing ink is greater than 12, ninhydrin is easily decomposed by strong alkali, causing the developer to lose its color-changing indicating ability.

[0074] Optionally, the pH adjuster includes but is not limited to: hydrochloric acid, sulfuric acid, nitric acid, acetic acid and citric acid.

[0075] In another embodiment, the color-changing ink further includes 1 to 3 parts of an adsorption material.

[0076] The adsorption material has a microporous structure, and its micropores can adsorb the sublimated ninhydrin gas molecules. By adding the adsorption material, the following beneficial effects can be produced: (1) the adsorption material is used to adsorb the ninhydrin gas molecules, so that the ninhydrin content in the color-changing ink can be kept stable, thereby preventing the ninhydrin content from becoming low due to thermal sublimation, thereby affecting the effect of the condensation color change reaction; (2) compared with the ninhydrin molecules directly dispersed in the ink system, the ninhydrin gas molecules adsorbed in the micropores are subject to relatively large van der Waals forces, and their movement speed in the micropores is much lower than the movement speed of the ninhydrin molecules directly dispersed in the ink system. When the human body touches the color-changing ink, substances such as oil or sweat secreted by the human body can also be adsorbed by the adsorption material and enter the micropores. At this time, affected by the molecular movement rate, the amino acid molecules are more easily captured by the ninhydrin molecules and undergo a condensation color change reaction, thereby greatly improving the efficiency of the condensation color change reaction, and thus making the color-changing ink undergo a significant condensation color change reaction within one minute.

[0077] It should be understood that when the adsorption material is black, the condensation color change reaction will not be visually visible. Therefore, adsorption materials other than black can be used as the adsorption material of the present invention.

[0078] Optionally, the adsorption material includes but is not limited to: white carbon black powder, zeolite powder, bentonite powder and microsilica powder.

[0079] In another embodiment, the color-changing ink further contains 0.1 to 1 parts of a hygroscopic material. By adding the hygroscopic material, after the color-changing ink dries to form a film, the hygroscopic material absorbs water molecules in the air, so that the ink layer maintains a certain water molecule content, which is beneficial to promote the hydrolysis of the second imine and further promote the reaction efficiency of the condensation color-changing reaction.

[0080] Optionally, the hygroscopic material includes, but is not limited to, magnesium chloride, calcium chloride, ferric chloride, aluminum chloride, potassium nitrate, and ammonium sulfate.

[0081] The above-mentioned color-changing ink contains a color developer, which can undergo a condensation color change reaction with the oil and sweat components secreted by the human body. When the above-mentioned color-changing ink is printed and dried, a touch color-changing area is formed. By touching the touch color-changing area with a finger, a specific blue-purple fingerprint pattern is formed in the touch color-changing area, thereby playing an identification role and preventing confusion of objects.

[0082] See also Figure 1 One embodiment of the present invention is a method for preparing the above-mentioned color-changing ink, comprising the following steps:

[0083] Step S10: adding 20 to 50 parts of a film-forming resin to 30 to 90 parts of a solvent, and stirring thoroughly until the film-forming resin is completely dissolved to obtain a first solution.

[0084] Step S20: adding 1 to 3 parts of a pH regulator to the first solution and stirring thoroughly to obtain a second solution.

[0085] Step S40: adding 0.5 to 6 parts of a color developer to the second solution and stirring thoroughly to obtain a color-changing ink.

[0086] In another embodiment, see Figure 2 , after step S20 and before step S40, further comprising:

[0087] Step S30: pre-treating the mixture of the developer and the adsorption material by heating.

[0088] Specifically, a mixture of 0.5 to 6 parts of a developer and 1 to 3 parts of an adsorption material is added to a sealed can, and the can is heated to 50-90°C to sublime the developer for 0.5-5 hours. During the heating period, the sealed can is continuously turned over to allow the adsorption material to saturate the adsorption of ninhydrin gas molecules, thereby obtaining a pretreated developer.

[0089] See also Figure 3 and Figure 4 A color-changing label 1 according to one embodiment includes a base layer 10 and a color-changing layer 20 that are stacked.

[0090] The base layer 10 is used to carry the color-changing layer 20. Optionally, the materials used to prepare the base layer 10 include but are not limited to: PE film, POF film, OPS film, PP film, PET film, PVC film and paper.

[0091] Preferably, the base layer 10 is a PP film, which has good heat shrinkage properties. When the color-changing label 1 is used for mineral water packaging, the color-changing label 1 needs to be heated and shrunk. During the heating process, ninhydrin absorbs heat and partially sublimates into gas molecules. When the color-changing ink contains an adsorption material, the gaseous ninhydrin molecules can be adsorbed by the micropores of the adsorption material. On the one hand, the color-changing ink can maintain a stable ninhydrin content, thereby avoiding the ninhydrin content from becoming low due to thermal sublimation, thereby affecting the effect of the condensation color change reaction; on the other hand, the condensation color change reaction efficiency of the ninhydrin molecules and amino acid molecules can be greatly improved.

[0092] The color-changing layer 20 is stacked on the base layer 10. The color-changing layer 20 is obtained by printing and drying any one of the color-changing inks provided in the first aspect of the present invention. The area where the color-changing layer 20 is provided forms a touch color-changing area.

[0093] When in use, the user touches the color-changing area with his finger. The oil or sweat components secreted by the human body will adhere to the color-changing ink and undergo a condensation color-changing reaction with the color developer, thereby presenting a specific blue-purple fingerprint pattern. Since fingerprints are unique, the resulting blue-purple fingerprint pattern is also unique.

[0094] In another embodiment, see Figures 5 to 8 A conventional graphic 30 is provided above the color-changing layer 20. The conventional graphic 30 is printed with ordinary ink and is used for positioning or marking.

[0095] Alternatively, the conventional image 30 may be a Chinese surname that is ranked highly, such as Wang, Li, Zhang, Liu, Chen, Yang, Huang, Zhao, Wu, Zhou, etc. Most users can find their corresponding surname among these characters. For example, a person with the surname "Wang" can touch the character "Wang" with their finger to generate a blue-purple fingerprint background on the character "Wang".

[0096] Optionally, the conventional graphic 30 is a group of 26 English letters arranged in a surrounding manner. Each user can find the first English letter corresponding to his or her surname from the 26 English letters. For example, a person with the surname "Gao" can touch the English letter G with his or her finger to generate a blue-purple fingerprint background on the English letter G.

[0097] Preferably, the conventional graphics 30 are three groups of 26 English letters arranged in a surrounding pattern. Since most users have names of two or three characters, most users can find the letters corresponding to their names from the above three groups of English letters. For example, a person with a last name of "Gao" and a first name of "Er" can touch G in the first group of English letters and E in the second group of English letters with their fingers to generate a blue-purple fingerprint background on the English letters G and E.

[0098] The above-mentioned color-changing label 1 and the color-changing layer 20 are printed using color-changing ink. The color-changing ink contains a color developer, which can undergo a condensation color change reaction with the oil and sweat components secreted by the human body. When the above-mentioned color-changing ink is printed and dried, a touch color-changing area is formed. By touching the touch color-changing area with a finger, a specific blue-purple fingerprint pattern is formed in the touch color-changing area, thereby playing an identification role and preventing confusion of items.

[0099] See also Figure 9A mineral water package according to one embodiment includes a bottle body 2 and a color-changing label 1. The color-changing label 1 is arranged around the outer surface of the bottle body 2. The color-changing label 1 is any one of the color-changing labels 1 provided in the third aspect of the present invention.

[0100] When using mineral water in public places such as conference rooms, you only need to touch a specific position of the color-changing area with your finger to form a specific blue-purple fingerprint pattern, so that you can easily distinguish your own mineral water, thereby preventing the mineral water from being confused and reducing unnecessary waste.

[0101] The following are specific examples.

[0102] Example 1

[0103] A first aspect of this embodiment provides a color-changing ink. The raw materials for preparing the color-changing ink include, measured in parts by mass, the following components: 20 parts of a film-forming resin, 30 parts of a solvent, 1 part of a pH adjuster, and 0.5 parts of a developer. In this embodiment, the film-forming resin is a water-based polyacrylate resin, the solvent is deionized water, the pH adjuster is hydrochloric acid, and the developer is ninhydrin.

[0104] The above-mentioned color-changing ink contains a color developer, which can undergo a condensation color change reaction with the oil and sweat components secreted by the human body. When the above-mentioned color-changing ink is printed and dried, a touch color-changing area is formed. By touching the touch color-changing area with a finger, a specific blue-purple fingerprint pattern is formed in the touch color-changing area, thereby playing an identification role and preventing confusion of objects.

[0105] See also Figure 1 A second aspect of this embodiment provides a method for preparing a color-changing ink, comprising the following steps:

[0106] (1) Add 20 to 50 parts of a film-forming resin to 30 to 90 parts of a solvent and stir thoroughly until the film-forming resin is completely dissolved to obtain a first solution.

[0107] (2) Add 1 to 3 parts of a pH regulator to the first solution and stir thoroughly to obtain a second solution.

[0108] (3) Add 0.5 to 6 parts of a color developer to the second solution and stir thoroughly to obtain a color-changing ink.

[0109] See also Figure 3 and Figure 4 The third aspect of this embodiment provides a color-changing label 1, which includes a stacked base layer 10 and a color-changing layer 20. The base layer 10 is a PP film, and the color-changing layer 20 is printed with the color-changing ink provided in this embodiment.

[0110] See also Figure 9The fourth aspect of this embodiment provides a mineral water package, which includes a bottle body 2 and a color-changing label 1. The color-changing label 1 is arranged around the outside of the bottle body 2. The color-changing label 1 is the color-changing label 1 provided in the third aspect of this embodiment.

[0111] Example 2

[0112] A first aspect of this embodiment provides a color-changing ink. The raw materials for preparing the color-changing ink, measured in parts by mass, include the following components: 35 parts of a film-forming resin, 60 parts of a solvent, 2 parts of a pH adjuster, 3 parts of a color developer, and 1 part of an adsorbent. In this embodiment, the film-forming resin is a water-based polyurethane resin, the solvent is deionized water, the pH adjuster is sulfuric acid, the color developer is ninhydrin, and the adsorbent is white carbon black powder.

[0113] The above-mentioned color-changing ink contains an adsorption material in its composition. The adsorption material has a microporous structure, and its micropores can adsorb the sublimated ninhydrin gas molecules. By adding the adsorption material, the following beneficial effects can be produced: (1) the adsorption of ninhydrin gas molecules by the adsorption material can maintain a stable ninhydrin content in the color-changing ink, thereby preventing the ninhydrin content from decreasing due to thermal sublimation, thereby affecting the effect of the condensation color change reaction; (2) compared with the ninhydrin molecules directly dispersed in the ink system, the ninhydrin gas adsorbed in the micropores is The molecules are subject to relatively large van der Waals forces, and their movement speed in the micropores is much lower than the movement speed of the ninhydrin molecules directly dispersed in the ink system. When the human body touches the color-changing ink, substances such as oil or sweat secreted by the human body can also be adsorbed by the adsorption material and enter the micropores. At this time, affected by the molecular movement rate, the amino acid molecules are more easily captured by the ninhydrin molecules and undergo condensation color change reactions, thereby greatly improving the efficiency of the condensation color change reaction, and causing the color-changing ink to undergo obvious condensation color change reactions within one minute.

[0114] See also Figure 2 The second aspect of this embodiment provides a method for preparing a color-changing ink, which comprises the following steps:

[0115] (1) Add 20 to 50 parts of a film-forming resin to 30 to 90 parts of a solvent and stir thoroughly until the film-forming resin is completely dissolved to obtain a first solution.

[0116] (2) Add 1 to 3 parts of a pH regulator to the first solution and stir thoroughly to obtain a second solution.

[0117] (3) Add 0.5 to 6 parts of a color developer and 1 to 3 parts of an adsorbent mixture into a sealed container, heat the container to 50-90°C to sublime the color developer for 2-5 hours, and continuously flip the sealed container during the heating period to allow the adsorbent to saturate with ninhydrin gas molecules.

[0118] (4) Add the pretreated developer to the second solution and stir thoroughly to obtain a color-changing ink.

[0119] See also Figures 5 to 8 The third aspect of this embodiment provides a color-changing label 1, which is similar to the color-changing label 1 of Example 2, except that a conventional graphic 30 layer is provided above the color-changing layer 20, and the conventional graphic is a group of 24 English letters arranged in a surrounding manner.

[0120] Example 3

[0121] A first aspect of this embodiment provides a color-changing ink. The raw materials for preparing the color-changing ink, measured in parts by mass, include the following components: 50 parts of a film-forming resin, 90 parts of a solvent, 3 parts of a pH adjuster, 6 parts of a color developer, 3 parts of an adsorbent material, and 1 part of a hygroscopic material. In this embodiment, the film-forming resin is polyvinyl pyrrolidone, the solvent is deionized water, the pH adjuster is citric acid, the color developer is ninhydrin, the adsorbent material is zeolite powder, and the hygroscopic material is calcium chloride.

[0122] The above-mentioned color-changing ink contains hygroscopic materials in its composition. By adding the hygroscopic materials, after the color-changing ink dries to form a film, the hygroscopic materials absorb water molecules in the air, so that the ink layer maintains a certain water molecule content, which is beneficial to promote the hydrolysis of the second imine and further promote the reaction efficiency of the condensation color-changing reaction.

[0123] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A color-changing ink, characterized in that: The raw materials for preparing the color-changing ink include the following components measured by mass: 20 to 50 parts of film-forming resin; 30 to 90 parts of solvent; 1~3 parts of adsorption material; 1 to 3 parts pH adjuster; as well as 0.5 to 6 parts of color developer; Wherein, the color developer is ninhydrin, and the adsorption material is selected from at least one of white carbon black, zeolite powder and microsilica powder.

2. The color-changing ink according to claim 1, characterized in that: The molecular weight of the film-forming resin is 40,000-150,000.

3. The color-changing ink according to claim 2, characterized in that: The film-forming resin is selected from at least one of water-based polyacrylate resin, water-based polyurethane resin and polyvinyl pyrrolidone.

4. The color-changing ink according to claim 3, characterized in that: The pH adjuster is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, acetic acid and citric acid.

5. The color-changing ink according to claim 1, characterized in that: It also includes 0.1 to 1 parts of hygroscopic material.

6. A method for preparing a color-changing ink, for preparing the color-changing ink according to any one of claims 1 to 4, characterized in that: The steps include: Add 20 to 50 parts of a film-forming resin to 30 to 90 parts of a solvent and stir thoroughly to obtain a first solution; Add 1 to 3 parts of a pH adjuster to the first solution and stir thoroughly to obtain a second solution; Heat-treating a mixture of 0.5 to 6 parts of a developer and 1 to 3 parts of an adsorbent material to obtain a pretreated developer; The pretreated developer is added to the second solution and stirred thoroughly to obtain a color-changing ink.

7. A color-changing label, characterized in that: The invention comprises a base layer and a color-changing layer which are stacked together, wherein the color-changing layer is obtained by printing the color-changing ink according to any one of claims 1 to 4.

8. A mineral water package, characterized in that: It comprises a bottle body and a color-changing label, wherein the color-changing label is the color-changing label according to claim 7.

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