Edible white ink for digital inkjet and preparation method thereof

Abstract

The present invention discloses an edible white ink for digital inkjet printing. The ink comprises, by weight, at least the following ingredients: 1-30% solvent, 1-20% sweetener, 0.1-1% stabilizer, 0.1-5% surfactant, 1-50% titanium dioxide emulsion, and the balance made up of deionized water. The ink exhibits high stability and exhibits no stratification or sedimentation during long-term storage. This significantly improves the ink's shelf life and durability, resulting in excellent results. Furthermore, the ink is safe, lacking excessive additives, surfactants, or other ingredients that may be harmful to the human body. This improves consumer satisfaction, complies with food regulations, and is suitable for widespread adoption in the food printing industry.

Description

Technical Field

[0001] The present invention relates to the field of edible ink, in particular to the field of IPC C09, and more specifically to an edible white ink for digital inkjet and a preparation method thereof. Background Art

[0002] Currently, the existing technology of edible ink mostly uses iron salts and cyclodextrin to ensure that the edible printing ink can have good viscosity and surface tension. Edible printing inks with such ingredients often have good adhesion to hydrophobic surfaces. However, during the production process, iron salts are easily oxidized, resulting in a dark color of the ink. The iron salt component must be strictly selected to avoid printing defects.

[0003] Chinese invention patent CN107955451B discloses an edible printing ink and its preparation method, which uses food ingredients such as iron salts, water, carbohydrate sweeteners, and colorants. Although it has a good adhesion effect on the food surface, the ink has a dark color and has not been effectively explored in terms of its stability and durability. Summary of the Invention

[0004] In order to solve the above problems, the first aspect of the present invention provides an edible white ink for digital inkjet. The raw materials include at least the following components, in weight percentage: 1-30% solvent, 1-20% sweetener, 0.1-1% stabilizer, 0.1-5% surfactant, 1-50% titanium dioxide emulsion, and deionized water to make up the balance.

[0005] Preferably, the solvent is one or more of glycerol, propylene glycol, ethanol, sorbitol, potassium lactate, and sodium lactate.

[0006] Preferably, the solvent is a mixture of propylene glycol, glycerol and ethanol, and the mass ratio of the three is (1-10):(10-20):(1-10).

[0007] Preferably, the solvent is a mixture of propylene glycol, glycerol and ethanol, and the mass ratio of the three is 5:15:5.

[0008] Preferably, the solvent is a mixture of potassium lactate, glycerol and ethanol, and the mass ratio of the three is (5-10):(5-10):(5-8).

[0009] Preferably, the sweetener is one or more of erythritol, fructose, lactitol, maltitol, and xylitol.

[0010] Preferably, the stabilizer is one or more of cyclodextrin, pregelatinized starch, and polydextrose.

[0011] Preferably, the surfactant is one or more of phospholipids, Tween 20, Tween 80, mono- and di-glycerol fatty acid esters.

[0012] Preferably, the formula of the titanium dioxide emulsion includes, by weight percentage: 5-40% moisturizing solvent, 1-10% emulsifier, 1-5% dispersant, 0.1-5% defoaming agent, 1-50% titanium dioxide, and deionized water as the balance.

[0013] Preferably, the moisturizing solvent is one or more of glycerol, propylene glycol, sorbitol, potassium lactate, and sodium lactate.

[0014] Preferably, the emulsifier is one or more of mono- and diglycerol fatty acid esters, Tween 20, Tween 80, cyclodextrin, and phospholipids.

[0015] Preferably, the dispersant is one or more of gelatin, xanthan gum, and gum arabic.

[0016] Preferably, the defoaming agent is one or more of Tween 20, Tween 40, Tween 60, Tween 80, and polydimethylsiloxane.

[0017] A second aspect of the present invention provides a method for preparing edible white ink for digital inkjet printing, characterized in that the method comprises at least the following steps:

[0018] S1: Preparation of titanium dioxide emulsion;

[0019] S2: The titanium dioxide emulsion prepared in S1 is mixed with other raw materials according to weight percentage, stirred, filtered, defoamed, and sterilized to obtain ink.

[0020] Preferably, the specific steps of S1 are:

[0021] (1) Weigh 5 / 8-7 / 10 of the mass of deionized water, heat to 85-95°C, add dispersant and emulsifier, and stir at 1800-2200 r / min for 15-25 minutes until uniform;

[0022] (2) adding the mixed solution obtained in step (1) and the remaining deionized water and moisturizing solvent into a material tank, stirring at 800-1000 r / min for 20-40 min, reducing the speed to 200-300 r / min, slowly adding titanium dioxide, adjusting the speed to 1500-2000 r / min, and dispersing and stirring for 1.5-3 hours. Cooling water is connected during the whole process to maintain the temperature of the material tank at 18-22°C;

[0023] (3) Grind the mixed solution obtained in step (2) with a nano-grinder for 4-8 hours, add defoaming agent in 3-4 times during the grinding process, connect cooling water during the whole process, and maintain the temperature of the material cylinder at 18-22°C; start sampling and testing the particle size and viscosity after grinding for 4 hours, and take samples every 30 minutes until the titanium dioxide emulsion particle size reaches D50 <150nm, D90 <300nm, and the viscosity <200CP, and then stop grinding;

[0024] (4) The ground titanium dioxide emulsion is filtered twice with a 0.45 μm filter to obtain the titanium dioxide emulsion.

[0025] Preferably, the diameter of the beads in the grinder is 1.0-3.0 mm, and the weight ratio of the beads to the mixed liquid is (1-2):1.

[0026] Preferably, the diameter of the beads in the grinder is 3.0 mm, and the weight ratio of the beads to the mixed liquid is 1.5:1.

[0027] Preferably, the specific steps of S2 are:

[0028] (1) Add deionized water, solvent, surfactant, sweetener, and stabilizer into a container according to the formula ratio, stir evenly at 500-800 r / min, continue to add titanium dioxide emulsion, and stir evenly at 800-1000 r / min;

[0029] (2) Filter the mixed solution obtained in step (1) twice with a 0.45 μm filter, and remove bubbles from the obtained filtrate under a vacuum degree of 0.06-0.1 MPa for 30-60 minutes;

[0030] (3) The mixed liquid after defoaming is pasteurized to obtain edible white ink.

[0031] Based on the technical problems existing in the existing technology, the applicant has discovered through experimental research that the use of titanium dioxide in edible ink can, on the one hand, reduce the darkness of the ink and significantly improve the whiteness of the ink, making the printed text, patterns, etc. clearer and more vivid. On the other hand, an appropriate amount of titanium dioxide can also significantly improve the printing speed and accuracy of the ink.

[0032] However, during further research, it was found that the content of titanium dioxide components and the processing technology have a significant impact on the quality and stability of the ink. Directly adding titanium dioxide to the ink and simply mixing it with water will cause the ink to stratify and settle, reducing the stability of the ink. At the same time, insufficient processing fineness of titanium dioxide will cause the ink to thicken and its fluidity to deteriorate, thereby clogging the nozzle and making it impossible to print on the machine.

[0033] In this regard, the applicant found through further experimental research that the components and proportions of titanium dioxide should be strictly controlled, especially in the preparation of titanium dioxide emulsion before adding titanium dioxide. The formula of titanium dioxide emulsion includes: moisturizing solvent 5-40%, emulsifier 1-10%, dispersant 1-5%, defoaming agent 0.1-5%, titanium dioxide 1-50%, and deionized water to make up the balance. The uniform dispersion of titanium dioxide in the ink and its compatibility with other components of the system are improved by sufficient mixing and grinding to avoid aggregation and sedimentation, so as to control the high fluidity and stability of the ink, improve printing smoothness, prevent clogging of the nozzle, and improve the whiteness, hiding power and durability of the ink. The ingredients are safe and comply with food regulations, and it can be widely promoted in the field of food printing.

[0034] Beneficial effects:

[0035] 1. The present invention provides an edible white ink for digital inkjet, which has high stability and does not delaminate or settle during long-term storage. The shelf life and durability of the ink are significantly improved, and the use effect is good.

[0036] 2. The edible white ink obtained by the present invention is safe in composition and does not use excessive additives, surfactants and other ingredients that may have an impact on the human body. It improves consumer satisfaction, complies with food regulations, and can be widely promoted in the field of food printing.

[0037] 3. The present invention uses the inorganic component titanium dioxide, which can improve the quick-drying property of the ink, reduce the darkness of the ink, and improve the whiteness of the ink, so that the text and patterns used for printing are clearer and the precision of digital inkjet is higher.

[0038] 4. The present invention strictly controls the composition of titanium dioxide emulsion through experimental exploration, thereby improving the stability of titanium dioxide and improving the compatibility of titanium dioxide emulsion with other components of ink, thereby increasing the durability of ink and making printed text more durable.

[0039] 5. The present invention has simple raw material components, simple preparation process, low cost, and good promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1. The effect of the ink prepared in Example 1 on printing biscuits;

[0041] Figure 2. The effect of the ink prepared in Example 2 on printing biscuits;

[0042] Figure 3. The effect of the ink prepared in Example 3 on printing biscuits. DETAILED DESCRIPTION

[0043] Example

[0044] Example 1:

[0045] Provided is an edible white ink for digital inkjet. The raw materials include the following components, calculated by weight percentage: 25% solvent, 8% sweetener, 1% stabilizer, 0.5% surfactant, 20% titanium dioxide emulsion, and the balance made up of deionized water.

[0046] The solvent is a mixture of propylene glycol, glycerol and ethanol, and the mass ratio of the three is 5:15:5.

[0047] The sweetener is a mixture of lactitol and fructose, with a mass ratio of 5:3.

[0048] The stabilizer is polydextrose.

[0049] The surfactant was Tween 20.

[0050] The formula of the titanium dioxide emulsion includes, by weight percentage, 20% of a moisturizing solvent, 2% of an emulsifier, 1% of a dispersant, 0.2% of a defoaming agent, 30% of titanium dioxide, and the balance made up of deionized water.

[0051] The moisturizing solvent is a mixture of glycerin and propylene glycol, and the mass ratio of the two is 1:1.

[0052] Emulsifiers are mono- and di-glycerides of fatty acids.

[0053] The dispersant is gum arabic.

[0054] The defoaming agent is Tween 60.

[0055] The method for preparing the edible white ink for digital inkjet as described above comprises the following steps:

[0056] S1: Preparation of titanium dioxide emulsion;

[0057] S2: The titanium dioxide emulsion prepared in S1 is mixed with other raw materials according to weight percentage, stirred, filtered, defoamed, and sterilized to obtain ink.

[0058] The specific steps of S1 are:

[0059] (1) Weigh 25 / 29 of deionized water, heat to 90°C, add dispersant and emulsifier, and stir at 2000 rpm for 20 minutes until uniform;

[0060] (2) Add the mixed solution prepared in step (1) and the remaining deionized water and moisturizing solvent into the material tank, stir at 900 r / min for 30 min, reduce the speed to 250 r / min, slowly add titanium dioxide, adjust the speed to 1800 r / min, disperse and stir for 2 hours, connect cooling water throughout the process, and maintain the material tank temperature at 20°C;

[0061] (3) Grind the mixed solution obtained in step (2) with a nano-grinder for 6 h, add defoaming agent in 4 times during the grinding process, connect cooling water during the whole process, and maintain the temperature of the material cylinder at 20°C; start sampling and testing the particle size and viscosity after grinding for 4 hours, and take samples every 30 minutes until the titanium dioxide emulsion particle size reaches D50 <150nm, D90 <300nm, and the viscosity <200CP, and stop grinding;

[0062] (4) The ground titanium dioxide emulsion is filtered twice with a 0.45 μm filter to obtain the titanium dioxide emulsion.

[0063] The diameter of the beads in the grinder is 3.0 mm, and the weight ratio of the beads to the mixed liquid is 1.5:1.

[0064] The specific steps of S2 are:

[0065] (1) Add deionized water, solvent, surfactant, sweetener, and stabilizer into a container according to the formula ratio, stir at 600 r / min, and continue to add titanium dioxide emulsion and stir at 900 r / min;

[0066] (2) The mixed solution obtained in step (1) was filtered twice with a 0.45 μm filter, and the obtained filtrate was defoamed under a vacuum degree of 0.08 MPa for 45 minutes;

[0067] (3) The mixed liquid after defoaming is pasteurized to obtain edible white ink.

[0068] Example 2:

[0069] An edible white ink for digital inkjet is provided. The specific implementation is the same as that of Example 1, except that:

[0070] The ink raw materials include the following components in weight percentage: 20% solvent, 15% sweetener, 1% stabilizer, 0.2% surfactant, 20% titanium dioxide emulsion, and deionized water as the balance.

[0071] The solvent is a mixture of potassium lactate, glycerol and ethanol, and the mass ratio of the three is 5:10:5.

[0072] The sweetener is a mixture of lactitol and erythritol, with a mass ratio of 10:5.

[0073] The stabilizer is polydextrose.

[0074] The surfactant was Tween 80.

[0075] Calculated by weight percentage, the formula of the titanium dioxide emulsion includes: 15% moisturizing solvent, 1% emulsifier, 1% dispersant, 35% titanium dioxide, and deionized water as the balance.

[0076] The moisturizing solvent is a mixture of glycerol and potassium lactate, with a mass ratio of 10:5.

[0077] The emulsifier is Tween 20.

[0078] The dispersing agent is gelatin.

[0079] Example 3:

[0080] An edible white ink for digital inkjet is provided. The specific implementation is the same as that of Example 1, except that:

[0081] Calculated by weight percentage, the ink raw materials include the following components: 23% solvent, 15% sweetener, 1% stabilizer, 0.2% surfactant, 20% titanium dioxide emulsion, and the balance made up of deionized water.

[0082] The solvent is a mixture of potassium lactate, glycerol and ethanol, and the mass ratio of the three is 10:5:8.

[0083] The sweetener is a mixture of fructose and erythritol, with a mass ratio of 10:5.

[0084] The stabilizer is pregelatinized starch.

[0085] The surfactant was Tween 20.

[0086] Calculated by weight percentage, the formula of the titanium dioxide emulsion includes: 13% moisturizing solvent, 2% emulsifier, 2% dispersant, 45% titanium dioxide, and deionized water as the balance.

[0087] The moisturizing solvent is a mixture of glycerol and potassium lactate, with a mass ratio of 10:3.

[0088] The emulsifier is Tween 80.

[0089] The dispersant is gum arabic.

[0090] Comparative Example 1:

[0091] Provided is an edible white ink for digital inkjet printing. The specific implementation is the same as that of Example 1, except that: the raw materials include the following components, by weight percentage: 25% solvent, 8% sweetener, 1% stabilizer, 0.5% surfactant, 8% titanium dioxide, and deionized water as the balance.

[0092] Comparative Example 2:

[0093] Provided is an edible white ink for digital inkjet printing. The specific implementation is the same as that of Example 2, except that, in terms of weight percentage, the formula of the titanium dioxide emulsion includes: 30% titanium dioxide and the balance made up of deionized water.

[0094] Comparative Example 3:

[0095] Provided is an edible white ink for digital inkjet, wherein the raw material composition is the same as that of Example 3, except that the titanium dioxide emulsion is prepared by simply mixing and stirring the raw materials evenly without grinding.

[0096] Performance testing:

[0097] 1. Physical and chemical parameters: The viscosity, surface tension, and stability of the edible white inks prepared in Examples 1-3 and Comparative Examples 1-3 were tested at 25° C. and standard atmospheric pressure. The average values of the measured results are recorded in Table 1.

[0098] 2. Printing effect comparison: The printing effect of the edible white inks prepared in Examples 1-3 was tested, and the average values of the measured results were recorded in Table 2.

[0099] 3. Printing color comparison: The printing colors of the edible white inks prepared in Examples 1-3 were compared. The effects of the inks prepared in Examples 1-3 for printing biscuits are shown in Figures 1-3, respectively.

[0100] Table 1

[0101]

[0102] The edible white inks prepared in Comparative Examples 1-3 all had the risk of delamination and nozzle clogging, and were not suitable for printing on a machine.

[0103] Table 2

[0104] Cleaning effect description Printing effect description Example 1 Clean the nozzle twice and the status is OK Continuous printing for 1 hour without any degradation of the printhead status Example 2 Clean the nozzle 3 times and the status is OK Continuous printing for 1 hour without any degradation of the printhead status Example 3 Clean the nozzle 3 times and the status is OK Continuous printing for 1 hour without any degradation of the printhead status

Claims

1. An edible white ink for digital inkjet, characterized in that: The raw materials include the following components by weight percentage: 25% solvent, 8% sweetener, 1% stabilizer, 0.5% surfactant, 20% titanium dioxide emulsion, and the balance made up of deionized water; The solvent is a mixture of propylene glycol, glycerol, and ethanol, with a mass ratio of 5:15:5; The sweetener is a mixture of lactitol and fructose, with a mass ratio of 5:3; The stabilizer is polydextrose; The surfactant was Tween 20; The formula of the titanium dioxide emulsion includes, by weight percentage: 20% moisturizing solvent, 2% emulsifier, 1% dispersant, 0.2% defoaming agent, 30% titanium dioxide, and the balance made up of deionized water; The moisturizing solvent is a mixture of glycerin and propylene glycol, with a mass ratio of 1:1; The emulsifier is mono- and diglycerol fatty acid esters; The dispersant is gum arabic; The defoaming agent is Tween 60; The method for preparing the edible white ink for digital inkjet as described above comprises the following steps: S1: Preparation of titanium dioxide emulsion; S2: The titanium dioxide emulsion prepared in S1 is mixed with other raw materials according to weight percentage, stirred, filtered, defoamed, and sterilized to obtain ink; The specific steps of S1 are: (1) Weigh 25 / 29 of deionized water, heat to 90°C, add dispersant and emulsifier, and stir at 2000 r / min for 20 minutes until uniform; (2) Add the mixed solution prepared in step (1) and the remaining deionized water and moisturizing solvent into the material tank, stir at 900 r / min for 30 min, reduce the speed to 250 r / min, slowly add titanium dioxide, adjust the speed to 1800 r / min, disperse and stir for 2 hours, connect cooling water during the whole process, and maintain the temperature of the material tank at 20°C; (3) Grind the mixed solution obtained in step (2) with a nano-grinder for 6 h. Add defoaming agent in 4 times during the grinding process. Connect cooling water during the whole process and keep the cylinder temperature at 20 °C. After grinding for 4 hours, start sampling to test the particle size and viscosity. Take samples every 30 minutes until the titanium dioxide emulsion particle size reaches D50 < 150 nm, D90 < 300 nm, and the viscosity < 200 CP. Stop grinding. (4) Filter the ground titanium dioxide emulsion twice through a 0.45 μm filter to obtain; The diameter of the zirconium beads in the grinder is 3.0 mm, and the weight ratio of zirconium beads to the mixed liquid is 1.5:1; The specific steps of S2 are: (1) Add deionized water, solvent, surfactant, sweetener, and stabilizer into the container according to the formula ratio, stir at 600 r / min, and then add titanium dioxide emulsion and stir at 900 r / min; (2) The mixed solution obtained in step (1) was filtered twice with a 0.45 μm filter, and the obtained filtrate was defoamed under a vacuum degree of 0.08 MPa for 45 minutes; (3) The mixture after defoaming is pasteurized to obtain edible white ink.

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