阅读说明：本技术 一种水包油型乳化墨水及其制备方法 (Oil-in-water emulsion ink and preparation method thereof ) 是由 李治军 陈义军 郭亨长 于 2020-05-29 设计创作，主要内容包括：本发明开发了一种改性麦芽糊精多功能助剂用于乳化墨水的制备,其具有乳化、润滑和保湿的多重功能,并采用微通道乳化法将其与有机溶剂、水溶性染料、触变剂、渗透剂、杀菌剂、防锈剂、pH调节剂、水等组分组合,制备得到了粒径均一、书写顺滑、保湿性优异、长期稳定的水包油型乳化墨水。(The invention discloses a modified maltodextrin multifunctional additive for preparing emulsion ink, which has multiple functions of emulsification, lubrication and moisture retention, and is combined with components such as an organic solvent, a water-soluble dye, a thixotropic agent, a penetrating agent, a bactericide, an antirust agent, a pH regulator, water and the like by adopting a micro-channel emulsification method to prepare the oil-in-water emulsion ink which has uniform particle size, smooth writing, excellent moisture retention and long-term stability.)

1. A modified maltodextrin having the structure:

wherein n is an integer of 6 to 20, R₁Is an alkyl group having 8 to 16 carbon atoms,

R₂is Na atom or maltodextrin with loss of hydroxyl H atom.

2. A process for preparing the modified maltodextrin of claim 1, comprising:

step (1): heating Alkylphenol Polyoxyethylene (APEO) and maleic anhydride with the same mole to 100-130 ℃ under the catalysis of methanesulfonic acid, and carrying out esterification reaction to obtain a product A with a terminal carboxylic group;

step (2): dissolving raw material maltodextrin in a proper amount of water, adding phosphorus pentoxide into the maltodextrin aqueous solution in batches within 1-1.5 h, keeping the reaction temperature not more than 40 ℃, and then keeping the temperature at 60-70 ℃ for 3-6 h to react to obtain a phosphate modified maltodextrin product B;

and (3): mixing the product A and the product B, adjusting the pH value to 8.5-9 by using a 5 wt.% NaOH aqueous solution, and reacting at 25-30 ℃ for 1.5h to obtain a product C;

and (4): product C was neutralized with 3 wt.% aqueous hydrochloric acid to pH 7 and filtered to give final product D.

3. The method for preparing modified maltodextrin according to claim 2, wherein the alkyl group of the alkylphenol ethoxylate (APEO) in the step (1) may be a linear alkyl group or an isomerized alkyl group having C8-C16, and the EO addition number of the polyoxyethylene ether may be any number of 6-20.

4. The process for preparing modified maltodextrins according to claim 2, wherein the DE value of the starting maltodextrins in step (2) is from 15 to 20, preferably from 17 to 20.

5. The method according to claim 2, wherein the phosphorus pentoxide in step (2) accounts for 2 to 6% by mass of the starting maltodextrin.

6. The method for preparing modified maltodextrin according to claim 2, wherein the number of moles of the product A in the step (3) is 3 to 10 times the number of moles of the raw material phosphorus pentoxide in the step (2).

7. An oil-in-water emulsion ink comprising:

wherein the multifunctional auxiliary agent is the modified maltodextrin as claimed in claim 1.

8. The oil-in-water type emulsified ink as claimed in claim 7, wherein the penetrating agent is fatty alcohol polyoxyethylene ether, which is fatty alcohol with C8-C15, the EO addition number of the polyoxyethylene ether is 8-20, and is preferably one or more of isooctanol polyoxyethylene ether, isomeric undecyl polyoxyethylene ether and isomeric tridecanol polyoxyethylene ether.

9. A method for preparing the oil-in-water type emulsion ink as claimed in claim 7 or 8, wherein the preparation method comprises the steps of using a device including a microchannel reactor including an inner tube and an outer tube, a digital display controller, an infusion pump, etc.:

step 1: dissolving 30% of multifunctional auxiliary agent in an organic solvent, uniformly stirring, and removing bubbles to obtain a dispersed phase;

step 2: fully and uniformly stirring water-soluble dye, 70% of multifunctional additive, thixotropic agent, penetrating agent, bactericide, antirust agent and pH regulator in water to obtain a continuous phase;

and step 3: connecting the outer tube of the microreactor to the vessel of the continuous phase and the inner tube of the microchannel reactor to the vessel of the dispersed phase;

and 4, step 4: and regulating the rotating speed of the infusion pump on a digital display controller, controlling the flow rate ratio of the continuous phase and the dispersed phase, and obtaining the emulsified ink at a liquid outlet.

10. The method for producing an oil-in-water emulsion ink according to claim 9, wherein the flow rate ratio of the continuous phase to the dispersed phase in step 4 is 9:1 to 4: 1.

Technical Field

The invention relates to oil-in-water type emulsion ink which comprises components such as a modified maltodextrin multifunctional auxiliary agent, an organic solvent, a water-soluble dye, a thixotropic agent, a penetrating agent, a bactericide, an antirust agent, a pH regulator, water and the like. The preparation method adopts a sleeve type micro-channel emulsification method.

Background

Emulsion ink ball-point pens are a new class of writing instruments, and the emulsion ink used therein is a new type of ink between oil-based inks and water-based inks. The emulsified ink has thixotropy similar to that of neutral ink, so that it has the advantages of smooth ink-out of neutral ball-point pen, full trace and no ink accumulation. Meanwhile, the formula of the emulsion ink contains a certain proportion of oily solvent, has the characteristics similar to an oily ball pen, and has smooth writing and good hand feeling. The emulsion ink belongs to an emulsion structure and has two types of oil-in-oil and oil-in-water. Emulsions are thermodynamically unstable systems, and the stability of different emulsions varies greatly, with the length being tens of years, and the length being hours or even minutes. As the pen core has uncertainty from production to the use period of consumers, the storage requirement of writing ink in the industry is usually more than 1 year, and the quality guarantee period of high-quality writing ink can reach more than 2 years.

The emulsion ink is a water-oil two-phase system, and the key auxiliary agent influencing the stability of the emulsion ink is an emulsifier. The hydrophilic end of the emulsifier commonly used for preparing the emulsion ink is ionic or polyether nonionic, the ionic is stable in water through the action of an electric double layer, and the polyether forms water-soluble micelles in water and stably exists in the water phase. However, during the long-term storage of the ink, the emulsifier adsorbed on the surface of the dispersed phase will slowly migrate and resolve into the continuous phase, causing instability of the whole system.

The emulsion ink is generally prepared by dispersing a dispersed phase in a continuous phase under strong shearing action by using a traditional high-speed shearing emulsification method. Patent CN102558966A discloses a dye type emulsion ink, which adopts a homogenizer to apply strong shear to the system to disperse the dispersed phase into the solvent to form a water-in-oil type emulsion ink. Patent CN106833126A discloses a method for obtaining finished products from pigments to emulsified inks by using a basket ball mill instead of a homogenizer. The above method has problems of high energy consumption, difficulty in controlling the size of emulsion droplets and polydispersity of emulsion droplets. The uneven emulsion liquid drops are unstable in the storage process and are easy to change such as agglomeration, flocculation and the like, so that the physicochemical parameters such as the viscosity of the ink are changed, the application performance is further adversely affected, and the writing performance of the ink is poor.

Disclosure of Invention

Aiming at the technical defects, the invention develops a modified maltodextrin multifunctional auxiliary agent for preparing the emulsion ink, which has multiple functions of emulsification, lubrication and moisture retention, and adopts a micro-channel emulsification method to prepare the oil-in-water emulsion ink with uniform particle size, smooth writing, excellent moisture retention and long-term stability.

The invention provides a modified maltodextrin which has the structure

Wherein n is an integer of 6 to 20, more preferably an integer of 8 to 16,

R₁is an alkyl group having 8 to 16 carbon atoms, more preferably a C10 to 14 carbon atom,

R₂is Na atom or maltodextrin with loss of hydroxyl H atom.

Meanwhile, the invention also provides a preparation method of the modified maltodextrin, which comprises the following steps:

step (1): heating Alkylphenol Polyoxyethylene (APEO) and maleic anhydride with the same mole to 100-130 ℃ under the catalysis of methanesulfonic acid, and carrying out esterification reaction to obtain a product A with a terminal carboxylic group;

step (2): dissolving raw material maltodextrin in a proper amount of water, adding phosphorus pentoxide into the maltodextrin aqueous solution in batches within 1-1.5 h, keeping the reaction temperature not more than 40 ℃, and then keeping the temperature at 60-70 ℃ for 3-6 h to react to obtain a phosphate modified maltodextrin product B;

and (3): mixing the product A and the product B, adjusting the pH value to 8.5-9 by using a 5 wt.% NaOH aqueous solution, and reacting at 25-30 ℃ for 1.5h to obtain a product C;

and (4): product C was neutralized with 3 wt.% aqueous hydrochloric acid to pH 7 and filtered to give final product D.

Wherein the end point of the reaction in step (1) is determined by the acid value of the test product, which is measured according to the test method in GB/T264-1983, Petroleum products acid value determination method.

And (2) determining the generation of the reaction product by testing the substitution degree of the reaction product in the step (3).

Wherein the degree of substitution refers to the amount of material in which the active hydroxyl groups on each D-glucose unit of the starch are substituted.

The aforementioned degree of substitution is tested by the following method:

accurately weighing 5.00g of sample (absolutely dry) in a 250m L iodine measuring flask, adding 50m L of distilled water, uniformly mixing, adding 3 drops of phenolphthalein indicator, uniformly mixing, dripping 0.1 mol/L sodium hydroxide solution until the reddish color is not disappeared, adding 25m L0.5.5 mol/L sodium hydroxide standard solution, stirring on a magnetic stirrer for 30min for saponification, washing the stopper and the flask wall of the iodine measuring flask with distilled water, then titrating the saponified solution containing excessive alkali with 0.5 mol/L hydrochloric acid standard solution until the reddish color is disappeared, namely the end point, the volume is V₁(m L) blank test in which 5.00g of absolute dried raw material raw maltodextrin was accurately weighed, the measurement procedure was the same as above, and the volume of 0.5 mol/L mol of hydrochloric acid consumed as a standard solution was recorded as V₂(mL)。

Wherein, the absolute drying means that the sample is placed in a constant-temperature drying oven at 105 +/-2 ℃ and is dried to constant weight.

The mass percentage of the substituent is calculated according to the formula (1):

when the degree of substitution of maltodextrin is DS, then

A is the substituent content; v₁Volume of hydrochloric acid consumed for the sample, m L: V₂M L, C is the concentration of hydrochloric acid standard solution, mol/L, M is the molar mass of a substituent group, g/mol, and M is the mass of a sample, g.

Wherein the degree of substitution of the product B is determined by M_BRepresents a phosphoric acid group;

measurement of degree of substitution of product BRecorded as DS₁。

The degree of substitution of the final product D was tested in two steps:

in a first step, the degree of substitution of starting material B by starting material A is tested (the blank maltodextrin should be its corresponding starting product B) with the substituent being replaced by M_DRepresenting the residue of product A after loss of the hydroxyl group, the degree of substitution being reported as DS₂。

Second step, degree of substitution DS of the final product D₃＝DS₁+DS₂。

Further, the heating temperature in the step (1) is 100-130 ℃, and further preferably 120-125 ℃.

Further, the alkyl group of the alkylphenol ethoxylate (APEO) in the step (1) may be a linear alkyl group or an isomerized alkyl group having C8 to C16, and is more preferably C10 to C14.

Further, the number of EO addition of the alkylphenol ethoxylate (APEO) in the step (1) may be any number from 6 to 20, and more preferably from 8 to 16.

Further, the system temperature in the feeding stage in the step (2) is not more than 40 ℃, and further preferably 35-40 ℃; the reaction time is 1 to 1.5 hours, and more preferably 1.3 to 1.5 hours.

Further, the reaction temperature in the heat preservation stage in the step (2) is 60-70 ℃, and further preferably 64-66 ℃; the time is 3 to 6 hours, and preferably 4 to 5 hours.

Further, the DE value of the raw material maltodextrin in the step (2) is 15-20, and more preferably 18-20.

Wherein the DE value refers to the glucose equivalent value (percentage of reducing sugars in dry matter in the sample) of the sample, in%, see GB/T20885 and 2007 glucose syrup.

Further, the mass of the phosphorus pentoxide in the step (2) is 2-6% of that of the raw material maltodextrin, and more preferably 3-5%.

Further, the mole number of the product A in the step (3) is 3 to 10 times, and more preferably 4 to 8 times that of the raw material phosphorus pentoxide in the step (2).

Meanwhile, the present invention also provides an oil-in-water type emulsion ink comprising:

12-20 parts by mass of an organic solvent, preferably 14-18 parts by mass;

5-15 parts by mass of a water-soluble dye, preferably 10-15 parts by mass;

5-10 parts by mass of a multifunctional additive, preferably 5-8 parts by mass;

0.1-0.5 part by mass of a thixotropic agent, preferably 0.2-0.3 part by mass;

0.2-0.5 part by mass of a penetrant, preferably 0.3-0.5 part by mass;

0.2 part by mass of a bactericide;

0.2 part by mass of an antirust agent;

0.1 to 0.5 part by mass of a pH regulator, preferably 0.1 to 0.4 part by mass;

50-80 parts by mass of water;

wherein the multifunctional auxiliary agent is the modified maltodextrin.

Further, the organic solvent is one or more of benzyl alcohol, phenethyl alcohol, ethylene glycol phenyl ether, propylene glycol phenyl ether and diethylene glycol phenyl ether, and can be preferably one or two of benzyl alcohol and ethylene glycol phenyl ether.

Further, the water-soluble dye is one or a combination of solvent red, solvent blue, solvent yellow, solvent violet and solvent black.

Further, the thixotropic agent is one or a combination of two of xanthan gum, arabic gum and bentonite, and can be preferably xanthan gum.

Further, the penetrating agent is fatty alcohol-polyoxyethylene ether, the carbon number of the penetrating agent is C8-C15 fatty alcohol, the EO addition number of the polyoxyethylene ether is 8-20, and the penetrating agent can be preferably one or a combination of more of isooctanol polyoxyethylene ether, isomeric undecyl polyoxyethylene ether and isomeric tridecanol polyoxyethylene ether.

Further, the bactericide is one or more of isothiazolinone substances and benzisothiazolinone substances, and can be preferably 1, 2-benzisothiazolin-3-one.

Further, the antirust agent is benzotriazole.

Further, the pH regulator is one or a combination of triethanolamine, diethanolamine, and triethylamine, and may preferably be triethanolamine.

In addition, the invention also provides a preparation method of the oil-in-water type emulsion ink, which uses a device comprising a microchannel reactor with an inner tube and an outer tube, a digital display controller, an infusion pump and the like, and the preparation method comprises the following steps:

step 1: dissolving 30% of multifunctional auxiliary agent in an organic solvent, uniformly stirring, and removing bubbles to obtain a dispersed phase;

step 2: fully and uniformly stirring water-soluble dye, 70% of multifunctional additive, thixotropic agent, penetrating agent, bactericide, antirust agent and pH regulator in water to obtain a continuous phase;

and step 3: connecting the outer tube of the microreactor to the vessel of the continuous phase and the inner tube of the microchannel reactor to the vessel of the dispersed phase;

and 4, step 4: and regulating the rotating speed of the infusion pump on a digital display controller, controlling the flow rate ratio of the continuous phase and the dispersed phase, and obtaining the emulsified ink at a liquid outlet.

Further, the flow rate ratio of the continuous phase to the dispersed phase in the step 4 is 9: 1-4: 1.

By the sleeve type micro-channel emulsification method, the emulsified ink with uniform particle size, good stability and smooth writing can be finally obtained.

The invention links maltodextrin molecules with phosphate groups and maleic anhydride modified APEO through esterification reaction to obtain a modified maltodextrin multifunctional additive which is used for preparing emulsion ink and has multiple functions of emulsification, moisture retention and lubrication. The oil-in-water type emulsion ink which has uniform particle size, smooth writing, excellent moisture retention and long-term stability is obtained by adopting a micro-channel emulsion method, and the preparation process has the advantages of low energy consumption and high efficiency.

Drawings

FIG. 1 is a schematic view of a telescopic microchannel reaction system. Wherein, the liquid storage device comprises a1, 7-liquid storage bottle, a 2, 6-high pressure infusion pump, a 3, 5-electronic flow meter, a 4-sleeve type micro-channel, an 8-dispersed phase liquid inlet, a 9-continuous phase liquid inlet, a 10-liquid outlet, an 11-digital display controller and a 12-micropore area.

FIG. 2 shows the IR spectra of maltodextrin, product A and product B, DF-1.

Detailed Description

The technical solution of the present invention is further explained below according to specific embodiments. It is to be understood that the invention is capable of other and different embodiments and its several details are capable of modification without departing from the scope of the invention, and that the description is intended to be illustrative in nature and not to be construed as limiting the invention.

The invention provides emulsion ink which comprises an organic solvent, a water-soluble dye, a multifunctional additive, a thixotropic agent, a penetrating agent, a bactericide, an antirust agent, a pH regulator and water.

The organic solvent of the emulsion ink is one or a combination of more of benzyl alcohol, phenethyl alcohol, ethylene glycol phenyl ether, propylene glycol phenyl ether and diethylene glycol phenyl ether, and can be preferably one or a combination of two of benzyl alcohol and ethylene glycol phenyl ether (available from Shanghai Michelin Biochemical technology Co., Ltd., the same below).

The water-soluble dye of the emulsified ink is one or more of solvent red 135, solvent blue 68, solvent yellow 44, solvent violet 13, and solvent black 5 (available from Shanghai Michelin Biochemical technology Ltd., the same applies hereinafter).

The thixotropic agent of the emulsion ink is one or a combination of two of xanthan gum (available from inner Mongolian Jianlong Biochemical Co., Ltd., trade name FX80, the same below), gum arabic (available from Shandong Runyuan bent axle Co., Ltd., the same below), bentonite (available from Shanghai Kai Yin chemical Co., Ltd., trade name: BENTONESD-1, the same below), and xanthan gum is preferable.

The penetrant of the emulsified ink is fatty alcohol-polyoxyethylene ether, the carbon number of which is C8-C16, the EO addition number of the polyoxyethylene ether is 8-20, and the penetrant can be preferably one or a combination of more of isooctanol polyoxyethylene ether, isomeric undecyl polyoxyethylene ether and isomeric tridecyl polyoxyethylene ether (purchased from Bailingwei science and technology Co., Ltd., the same below).

The biocide of the emulsified ink is a combination of one or more of isothiazolinone and benzisothiazolinone, such as 1, 2-benzisothiazolin-3-one (available from Shanghai Aladdin Biotech, Inc.).

The rust inhibitor for the emulsion ink was benzotriazole (available from Shanghai Aladdin Biotech Co., Ltd.).

The pH adjuster of the emulsion ink is one or a combination of triethanolamine, diethanolamine, and triethylamine, and preferably triethanolamine (available from the shochu science and technology co., ltd., hereinafter).

Further, the multifunctional auxiliary agent of the emulsified ink is modified maltodextrin, and the preparation process comprises the following steps:

step (1): heating alkylphenol ethoxylates (APEO) (purchased from Bailingwei science and technology Limited, the same below) and equimolar maleic anhydride (purchased from Jiangsu Zhengxu chemical Limited, the same below) to 100-130 ℃ under the catalysis of methanesulfonic acid (purchased from Baiyun chemical Limited, the same below), and carrying out esterification reaction to obtain a product A with a terminal carboxylic group;

step (2): dissolving a raw material maltodextrin (purchased from Shandongteng Wang chemical Co., Ltd., the same below) in a proper amount of water, adding phosphorus pentoxide (purchased from Nanjing chemical reagent Co., Ltd., the same below) into the maltodextrin aqueous solution in batches within 1-1.5 h, keeping the temperature at 60-70 ℃ for 3-6 h, and reacting to obtain a phosphate modified maltodextrin product B;

and (3): mixing the product A and the product B, adjusting the pH value to 8.5-9 by using a 5 wt.% NaOH aqueous solution, and reacting at 25-30 ℃ for 1.5h to obtain a product C;

and (4): product C was neutralized with 3 wt.% aqueous hydrochloric acid to pH 7 and filtered to give final product D.

Wherein the end point of the reaction in step (1) is determined by the acid value of the test product, which is measured according to the test method in GB/T264-1983, Petroleum products acid value determination method.

And (2) determining the reaction end point by testing the degree of substitution of the reaction product in the step (3).

Wherein the degree of substitution refers to the amount of material in which the active hydroxyl groups on each D-glucose unit of the starch are substituted.

The degree of substitution was tested by the following method:

accurately weighing 5.00g of sample (absolutely dry) in a 250m L iodine measuring flask, adding 50m L of distilled water, uniformly mixing, adding 3 drops of phenolphthalein indicator, uniformly mixing, dripping 0.1 mol/L sodium hydroxide solution until the reddish color is not disappeared, adding 25m L0.5.5 mol/L sodium hydroxide standard solution, stirring on a magnetic stirrer for 30min for saponification, washing the stopper and the flask wall of the iodine measuring flask with distilled water, then titrating the saponified solution containing excessive alkali with 0.5 mol/L hydrochloric acid standard solution until the reddish color is disappeared, namely the end point, the volume is V₁(m L) blank test in which 5.00g of absolute dried raw material raw maltodextrin was accurately weighed, the measurement procedure was the same as above, and the volume of 0.5 mol/L mol of hydrochloric acid consumed as a standard solution was recorded as V₂(mL)。

Wherein, the absolute drying means that the sample is placed in a constant-temperature drying oven at 105 +/-2 ℃ and is dried to constant weight.

The mass percentage of the substituent is calculated according to the formula (1):

when the degree of substitution of maltodextrin is DS, then

A is the substituent content; v₁Volume of hydrochloric acid consumed for the sample, m L: V₂M L, C is the concentration of hydrochloric acid standard solution, mol/L, M is the molar mass of a substituent group, g/mol, and M is the mass of a sample, g.

Wherein the degree of substitution of the product B is determined by M_BRepresents a phosphoric acid group;

the degree of substitution of the product B measured is recorded as DS₁。

The degree of substitution of the final product D was tested in two steps:

in a first step, the degree of substitution of starting material B by starting material A is tested (the blank maltodextrin should be its corresponding starting product B) with the substituent being replaced by M_DRepresenting the residue of product A after loss of the hydroxyl group, the degree of substitution being reported as DS₂。

Second step, degree of substitution DS of the final product D₃＝DS₁+DS₂。

The catalyst in the step (1) is methanesulfonic acid (purchased from Kyowa Baiyurt chemical Co., Ltd., the same below), and the heating temperature is 100-130 ℃, and more preferably 120-125 ℃.

The alkyl group of the Alkylphenol Polyoxyethylene Ether (APEO) in the step (1) can be a C8-C16 straight-chain alkyl group or an isomerized alkyl group, and is further preferably C10-C14; the number of EO adducts in the polyoxyethylene ether may be any number from 6 to 20, and more preferably from 8 to 16.

The system temperature in the feeding stage in the step (2) is not more than 40 ℃, and the preferable temperature is 35-40 ℃; the time of the feeding stage is 1-1.5 h, and the preferable time is 1.3-1.5 h; the reaction temperature in the heat preservation stage is 60-70 ℃, and the preferable temperature is 64-66 ℃; the time of the heat preservation stage is 3-6 h, and the preferable time is 4-5 h.

The DE value of the raw material maltodextrin in the step (2) is 15-20, and further preferably 17-20.

Wherein, the DE value refers to the glucose equivalent value (percentage of reducing sugar in dry matter in the sample) of the sample, and the unit is percent, see GB/T20885 and 2007 glucose syrup.

In the step (2), the mass of the phosphorus pentoxide is 2-6% of that of the raw material maltodextrin, and the preferable mass is 3-5%.

The mole number of the product A in the step (3) is 3-10 times, and more preferably 4-8 times that of the raw material phosphorus pentoxide in the step (2).

The preparation method of the emulsion ink comprises the following steps:

step 1: preparation of OP-1

Dissolving 30% of multifunctional auxiliary agent in organic solvent, stirring uniformly, and removing bubbles for later use.

Step 2: preparation of WP-1

Water-soluble dye, 70% of multifunctional additive, thixotropic agent, penetrating agent, bactericide, antirust agent and pH regulator are fully and uniformly stirred in water for later use.

The specific preparation method is shown in the attached figure 1, and the sleeve-type microchannel (4) (purchased from Shenzhen Yizhen technology Limited) consists of an inner tube and an outer tube, wherein the inner tube and the outer tube respectively flow into the disperse phase OP-1 and the continuous phase WP-1 to be connected. The liquid storage bottle (1) of the disperse phase OP-1 is connected with a high-pressure infusion pump (2), flows into the inner pipe from a disperse phase liquid inlet (8), and the flow rate of the inner pipe is measured by an electronic flowmeter (3). The liquid storage bottle (7) of the continuous phase WP-1 is connected with a high-pressure infusion pump (6), flows into the inner tube from a liquid inlet (9) of the continuous phase, the flow rate of the inner tube is measured by an electronic flowmeter (5), and the flow rates of the dispersed phase and the continuous phase are controlled by a digital display controller (11). When the dispersed phase flows to the micropore area (12) in the inner pipe, the dispersed phase flows into the continuous phase under the driving of the internal and external pressure difference, and is mixed with the continuous phase in a micro-channel in a cross flow manner, and the mixed emulsion is collected at the liquid outlet (10) to prepare the emulsified ink.

Wherein the outer diameter of the inner pipe of the micro-channel is 10-15 mm, the pipe wall of the inner pipe is provided with a section of micropore area, the length of the micropore area is 1-1.5 cm from the feed inlet, the aperture ratio is 20-30%, the aperture of the micropore is 2-8 μm, and the annular gap between the outer wall of the inner pipe and the inner wall of the outer pipe is 0.1-0.8 mm.

When the mobile phase is in turbulent flow and transition flow, the mobile phase is unstable fluid, and when the unstable fluid is contacted with the dispersion phase, the uniform particle size is difficult to control. The uniformity of the particle size is represented by a PDI value (particle size distribution coefficient), and a higher value indicates a more dispersed particle size distribution, and a smaller value indicates a more concentrated particle size distribution.

Under the laminar flow state, when the flow is unchanged and the annular gap is reduced, the flow velocity is increased, the mobile phase and the dispersed phase can be quickly mixed, and the particle size is reduced, wherein the annular gap of the microchannel is 0.1-0.8 mm.

As the continuous phase changes from a larger pipe diameter to a smaller pipe diameter when flowing into the annular gap, the stability of the continuous phase can be ensured only by the fluid state flowing for a certain distance in the annular gap, wherein the microporous region is 6-10 cm away from the feed inlet.

When the dispersed phase flows into the continuous phase through the micropores, the pore diameter of the micropores directly determines the size of the initial particle diameter, and when the pore diameter of the micropores is smaller, the particle diameter of the prepared emulsified ink is smaller, wherein the pore diameter of the micropores is 2-8 mu m.

And the flow rate ratio of the continuous phase WP-1 to the dispersed phase OP-1 is adjusted to be 9: 1-4: 1, so that the emulsified ink with uniform particle size, good stability and smooth writing is obtained at a liquid outlet.

The inventor creatively connects hydroxyl on a maltodextrin molecular structure with phosphate groups through esterification reaction to obtain the modified maltodextrin, which not only can play a role in moisturizing, but also can enable the modified maltodextrin to be adsorbed on the surfaces of a ball and a bowl seat under the adsorption action of the phosphate ester bonds and metal atoms during writing, and a boundary lubricating film is formed on the surface of a contact point of the modified maltodextrin, so that the effect of reducing the friction coefficient is achieved. In addition, the inventors further modified the phosphate-modified maltodextrin with maleic anhydride-modified APEO, thereby introducing hydrophobic groups, imparting emulsifying properties to the maltodextrin. The modified maltodextrin prepared by the method plays multiple roles of emulsification, moisture preservation and lubrication in the emulsion ink.

In addition, the inventor adopts a micro-channel emulsification method to prepare the emulsified ink, further limits the key parameters of the micro-channel, ensures uniform particle size and improves the stability of the emulsified ink. Compared with the conventional mechanical emulsification method, the emulsified ink prepared by the method has smaller particle size, is easy to flow in the inner channel of the pen point, and is smooth in ink discharge.

In conclusion, the inventor optimizes the ink formula and the preparation process to obtain the emulsified ink which is smooth in writing, good in moisture retention and stable for a long time, and the preparation process is low in energy consumption, high in efficiency and suitable for industrial production.

Hereinafter, the gel ink and the method for preparing the same according to one embodiment of the present invention will be described in detail with reference to specific examples.