TWI695919B - Digital printing ink - Google Patents

Abstract

Provided is a digital printing ink, for forming an inkjet pattern on a fabric, including chitosan, a surfactant, and a balance of a solvent. The chitosan has a weight-average molecular weight of 200,000 to 300,000. The surfactant includes a polyglycol, an ethylene oxide, or a combination thereof. The digital printing ink has a viscosity of 2 cps to 12 cps, a surface tension of 28 dyne/cm to 40 dyne/cm, and a pH value of 6 to 8. A content of the chitosan is 5 wt.% to 10 wt.%, and a content of the surfactant is 2 wt.% to 5 wt.%, based on the total weight of the digital printing ink.

Description

Digital printing ink

The invention relates to an ink, and in particular to a digital printing ink.

For the functional apparel (such as sports apparel) currently on the market, most of them use the impregnation pressure suction method to provide the functional dyeing solution to the fabric to obtain the required function. However, since the impregnation pressure suction method discharges a large amount of unused dye and water, there is a problem of excessive waste of resources.

In order to solve the above-mentioned problems, coating or screen printing methods are currently used to provide functional ink on the fabric on both sides or partially. However, in the process of coating or screen printing, a high concentration of waste liquid is generated, and the function is not easy to control due to the permeability of the ink.

The invention provides a digital spray printing ink, which has a hygroscopic agent and can be applied to functional clothing.

The invention provides a digital spray printing ink which has chitin as a bacteriostatic agent and can be applied to functional clothing.

The digital inkjet ink of the present invention includes a hygroscopic agent, a surfactant, an antifreeze agent, and a remaining amount of solvent. Hygroscopic agents include block copolyetheresters. Surfactants include acrylic block copolymers. Antifreeze agents include ethylene glycol. The digital printing ink has a viscosity of 2 cps to 12 cps and a surface tension of 28 dyne/cm to 40 dyne/cm, and the pH value of the digital printing ink is between 6 and 8. Based on the total weight of the digital printing ink, the moisture absorbent content is between 5 wt.% and 11 wt.%, and the surfactant content is between 3 wt.% and 10 wt.%. The content of antifreeze is between 3 wt.% and 5 wt.%.

In an embodiment of the present invention, a coupling agent is further included. The coupling agent is, for example, a polymer having an ethylene oxide side chain, wherein the content of the coupling agent is between 0.01 wt.% and 0.35 wt.% based on the total weight of the digital printing ink.

In an embodiment of the present invention, a humectant is further included. The humectant is, for example, glycerin, wherein the content of the humectant is between 2 wt.% and 5 wt.% based on the total weight of the digital printing ink.

In an embodiment of the invention, it further includes an acid-base regulator. The acid-base adjusting agent is, for example, triethanolamine (TEOA), wherein the content of the acid-base adjusting agent is between 0.01 wt.% and 0.1 wt.% based on the total weight of the digital printing ink.

In an embodiment of the invention, the solvent is, for example, deionized water.

The digital printing ink of the present invention includes chitin, a surfactant and a remaining amount of solvent. Chitin has a weight average molecular weight of 200,000 to 300,000. Surfactants include polyethylene glycol, ethylene oxide, or a combination thereof. The digital printing ink has a viscosity of 2 cps to 12 cps and a surface tension of 28 dyne/cm to 40 dyne/cm, and the pH value of the digital printing ink is between 6 and 8. Based on the total weight of the digital printing ink, the content of chitin is between 5 wt.% and 10 wt.%, and the content of surfactant is between 2 wt.% and 5 wt.%.

In an embodiment of the invention, it further includes an acid-base regulator. The acid-base regulator is, for example, triethanolamine, phosphate solution or a combination thereof, wherein the content of the acid-base regulator is between 0.1 wt.% and 0.4 wt.% based on the total weight of the digital printing ink.

In an embodiment of the present invention, a coupling agent is further included. The coupling agent is, for example, a polymer having an ethylene oxide side chain, wherein the content of the coupling agent is between 0.01 wt.% and 0.06 wt% based on the total weight of the digital printing ink.

In an embodiment of the present invention, a humectant is further included. The humectant is, for example, glycerin, wherein the content of the humectant is between 4 wt.% and 6 wt.% based on the total weight of the digital printing ink.

In an embodiment of the present invention, a co-solvent is further included. The co-solvent is, for example, propylene glycol methyl ether, wherein the content of the co-solvent is between 4 wt.% and 6 wt.% based on the total weight of the digital printing ink.

In an embodiment of the invention, the solvent is, for example, deionized water.

In an embodiment of the present invention, the polyethylene glycol has a weight average molecular weight of 400 to 600, for example.

Based on the above, in the digital printing ink of the present invention, since it contains a hygroscopic agent, it can have the ability to adjust humidity when applied to fabrics. In addition, since the digital printing ink of the present invention contains chitin, it can have bacteriostatic ability when applied to fabrics. Moreover, the digital printing ink of the present invention has a viscosity between 2 cps and 12 cps, a surface tension between 28 dyne/cm and 40 dyne/cm, and a pH between 6 and 8. The digital inkjet ink has proper fluidity, which can facilitate droplet formation and permeability, and there will be no sediment in the ink that will cause the nozzle of the inkjet device to become clogged and will not corrode the inkjet device's nozzle.

In order to make the above-mentioned features and advantages of the present invention more obvious and understandable, the embodiments are specifically described below in conjunction with the accompanying drawings for detailed description as follows.

The digital printing ink of the present invention can make the fabric have full or partial function through digital precision printing, so it can be applied to clothing, home decoration, such as sportswear, yoga wear, vest underwear, table towels, bedding sets Wait. In addition, since the digital inkjet ink of the present invention is formed on the fabric using digital precision inkjet printing, compared with the traditional impregnated pressure suction or coating method, the dosage and processing energy requirements can be saved by about three-thirds Second, and can accurately control the function of the ink. Furthermore, since the digital printing ink of the present invention contains a hygroscopic agent and/or chitin, the fabric can be provided with humidity adjusting ability and/or bacteriostatic ability.

The digital printing ink of the present invention will be described in detail below.

Digital printing ink with humidity adjustment capability

The digital inkjet printing ink with humidity adjustment capability of the present invention mainly contains a moisture absorbent, a surfactant, an antifreeze agent, and a remaining amount of solvent. The digital printing ink of the present invention has a viscosity of 2 cps to 12 cps, so that the ink droplets printed can have a suitable size, and the ink can have a suitable fluidity to facilitate digital precision printing. In addition, the digital printing ink with humidity adjustment capability of the present invention has a surface tension of 28 dyne/cm to 40 dyne/cm, and thus can facilitate the formation of ink droplets and the permeability of ink. In the embodiment of the present invention, the ink ejected by digital precision printing has a particle size of 0.25 μm to 0.6 μm, for example, so that the problem of nozzle clogging during digital precision printing can be avoided, and the ink can have Better color rendering characteristics. In addition, the digital printing ink with humidity adjustment capability of the present invention has a pH value between 6 and 8, so that it is possible to avoid corrosion of the nozzle of the printing device and to prevent the ink from depositing on the nozzle and causing blockage.

In the digital printing ink with humidity adjustment capability of the present invention, the hygroscopic agent includes a block copolyetherester. Examples of the block copolyetherester are, for example, polyetherester PEM (trade name, manufactured by Far East New Century Co., Ltd.) or polyetherester SRT (trade name, manufactured by Sino-Japan Synthetic Chemical Co., Ltd.). Based on the total weight of the digital printing ink of the present invention, the content of the moisture absorbent is between 5 wt.% and 11 wt.%. Within this range, the hygroscopic agent can effectively absorb moisture. For example, when the hygroscopic agent is included in the digital printing ink with humidity adjustment capability of the present invention in the above content range, after the ink is printed on the fabric to form a functional pattern, it can be effectively absorbed and used The sweat discharged from the skin of the user, and when the sweat evaporates, the user can have a cool and comfortable feeling. When the content of the hygroscopic agent is less than 5 wt.%, the digital printing ink cannot have a good moisture absorption effect. When the content of the hygroscopic agent is greater than 11 wt.%, the surface tension of the digital printing ink will be reduced, and it is not easy to effectively control the degree of diffusion of the hygroscopic ink, which may easily cause excessive diffusion of functional patterns and destroy the original pattern design. .

In the digital printing ink with humidity adjustment capability of the present invention, the surfactant includes an acrylic block copolymer. An example of the acrylic block copolymer is, for example, Dispex® Ultra PX 4575 (trade name, manufactured by BASF). The content of the surfactant is between 3 wt.% and 10 wt.% based on the total weight of the digital printing ink with humidity adjustment capability of the present invention. Within this range, the surfactant can maintain the size stability of the particles in the ink (eg, hygroscopic agent, etc.). When the content of the surfactant is less than 3 wt.%, the dispersion in the ink cannot be effectively dispersed, and precipitates or aggregates may be generated. When the content of the surfactant is greater than 10 wt.%, the aggregates will lose their coagulation effect due to the excessive repulsion generated by the surfactant.

In the digital printing ink with humidity adjustment capability of the present invention, the antifreeze agent includes ethylene glycol. Based on the total weight of the digital printing ink of the present invention, the content of the antifreeze is between 3 wt.% and 5 wt.%. The antifreeze agent can prevent the digital printing ink of the present invention from condensing under too low temperature and affecting the printing. When the content of antifreeze is less than 3 wt.%, the digital printing ink may not have sufficient anti-coagulation effect at low temperatures. When the content of antifreeze is between 3 wt.% and 5 wt.%, in addition to sufficient anti-coagulation effect, it can also have a moisturizing function. When the content of antifreeze is greater than 5 wt.%, it is easier to generate acidic substances, which will corrode the nozzle of the printing device.

The digital printing ink with humidity adjustment capability of the present invention may further contain a coupling agent. The coupling agent is, for example, a polymer having an ethylene oxide side chain. An example of a polymer of an ethylene oxide side chain is Surfynol 465 (trade name, manufactured by Nissin Chemical Industries). The content of the coupling agent is between 0.01 wt.% and 0.35 wt.% based on the total weight of the digital printing ink with humidity adjustment capability of the present invention. The coupling agent can effectively control the surface tension of the ink, thereby improving the smoothness of the printing and optimizing the ink droplet formation. When the content of the coupling agent is less than 0.01 wt.%, the surface tension of the ink cannot be effectively reduced, so that the smoothness of the printing and the permeability of the ink to the fabric are affected. When the content of the coupling agent is greater than 0.35 wt.%, the surface tension of the ink is too low, so that the surface of the head of the printing device is likely to contain ink, which affects the state of ink droplets. In other words, the digital printing ink with humidity adjustment capability of the present invention can have a surface tension of 28 dyne/cm to 40 dyne/cm by including an appropriate content of the coupling agent, and the appropriate content is, for example, 0.01 wt .%. to 0.35 wt.%.

The digital printing ink with humidity adjustment capability of the present invention may further contain a humectant. The humectant is, for example, glycerin. The content of the humectant is between 2 wt.% and 5 wt.% based on the total weight of the digital printing ink with humidity adjustment capability of the present invention. Within this range, the humectant can ensure that the digital printing ink will not congeal during the printing process and deposit or block the print head. When the content of the humectant is less than 2 wt.%, it may not be possible to effectively avoid the condensation of digital printing ink. When the content of the humectant is greater than 5 wt.%, it is easy to cause the drying speed of the ink on the fabric to be too slow, which reduces the production speed of the overall digital printing process.

The digital printing ink with humidity adjusting ability of the present invention may further contain an acid-base adjusting agent. The acid-base regulator is, for example, triethanolamine. The content of the acid-base adjusting agent is between 0.01 wt.% and 0.1 wt.% based on the total weight of the digital printing ink with humidity adjustment capability of the present invention. Within this range, the acid-base regulator can ensure that the pH value of the digital printing ink with humidity adjustment capability of the present invention is between 6 and 8. When the content of the acid-base regulator is less than 0.01 wt.%, it may not be effective to avoid maintaining the pH of the digital printing ink between 6 and 8. When the content of the acid-base adjuster is greater than 0.1 wt.%, the pH of the ink tends to be alkaline, which will affect the solubility of each component in the ink, which may easily cause sediment or block the nozzle.

In the digital printing ink with humidity adjustment capability of the present invention, the solvent is, for example, deionized water, but the present invention is not limited thereto.

The following will test and evaluate the digital printing ink with humidity adjustment capability of the present invention.

The composition of the digital printing ink of Experimental Example 1 to Experimental Example 5 is shown in Table 1. In each experimental example, the humectant was glycerin, the antifreeze was ethylene glycol, the surfactant was Disper Ultra PX4575 (manufactured by BASF), the coupling agent was Surfynol 465 (manufactured by Nissin Chemical Industries), and the acid-base adjustment The agent is triethanolamine.

Table 1 Experimental Example 1 Experimental Example 2 Experimental Example 3 Experimental Example 4 Experimental Example 5 Hygroscopic agent Polyetherester SRT 5 wt.% Polyetherester SRT 8 wt.% Polyetherester SRT 10 wt.% Polyetherester SRT 11 wt.% Polyetherester PEM 5 wt.% moisturizer 3 wt.% 3 wt.% 3 wt.% 3 wt.% 3 wt.% Antifreeze 5 wt.% 5 wt.% 5 wt.% 5 wt.% 3 wt.% Surfactant 3.5 wt.% 5 wt.% 7 wt.% 10 wt.% 4 wt.% Coupling agent 0.28 wt.% 0.04 wt.% 0.10 wt.% - 0.33 wt.% Acid-base regulator - - 0.05 wt.% 0.10 wt.% 0.04 wt.% Deionized water 83.22 wt.% 78.96 wt.% 74.85 wt.% 70.9 wt.% 84.63 wt.% Viscosity (cps) 3.26 7.1 10.2 11.6 3.84 Surface tension (dyne/cm) 31.68 30.98 32.2 36.2 28.2 pH value 6.35 6.06 6.14 6.73 7.73 Test nozzle EPSON DX5 EPSON DX5 EPSON DX5 StarFire SG1024/LA StarFire SG1024/LA EPSON DX5

It can be seen from Table 1 that the inks of Experimental Examples 1 to 5 have viscosities ranging from 2 cps to 12 cps, surface tension ranging from 28 dyne/cm to 40 dyne/cm, and pH values ranging from 6 to 8 Therefore, the inks of Experimental Examples 1 to 5 have proper fluidity, which can facilitate droplet formation and permeability, and can avoid the problems of ink deposition and nozzle clogging.

>Storage stability test>

After placing the inks of Experimental Example 1 to Experimental Example 5 in an oven at 60°C and a refrigerator at 5°C for 15 days, wait for the ink to return to normal temperature to observe whether there is delamination or sediment, and measure the viscosity. According to the test results, the inks of Experimental Examples 1 to 5 have no delamination and deposits and the viscosity changes are less than 5% after being placed at high and low temperatures, which means that the inks of Experimental Examples 1 to 5 are highly stable It can be stored at room temperature for 1 year to 2 years without deterioration.

>Evaluation of fabric color difference>

Print the inks of Experimental Example 1 to Experimental Example 5 on polyethylene terephthalate (PET) fabric, and measure the color space value of the fabric before and after printing with a spectrophotometer (Datacolor 650) (CIE Lab value), it can be seen that the CIE ΔE of the fabric before and after printing with the inks of Experimental Examples 1 to 5 does not exceed 0.1, that is, the inks of Experimental Examples 1 to 5 will not cause the color of the fabric influences.

>Fabric Selectivity>

The inks of Experimental Example 1 to Experimental Example 5 were printed on 100% polyester fiber fabric, polyethylene terephthalate/nylon blend fabric, polyethylene terephthalate/cotton blend fabric and cotton All fabrics can effectively form precise spray patterns on each fabric. That is, the inks of Experimental Examples 1 to 5 can be applied to various fabrics on the market.

Digital printing ink with antibacterial ability

The digital spray printing ink with antibacterial ability of the present invention mainly contains chitin, surfactant and the remaining amount of solvent. The digital printing ink of the present invention has a viscosity of 2 cps to 12 cps, so that the ink droplets printed can have a suitable size, and the ink can have a suitable fluidity to facilitate digital precision printing. In addition, the digital printing ink with bacteriostatic ability of the present invention has a surface tension of 28 dyne/cm to 40 dyne/cm, so it can be advantageous for ink droplet formation and ink permeability. In the embodiment of the present invention, the ink ejected by digital precision printing has a particle size of 0.25 μm to 0.6 μm, for example, so that the problem of nozzle clogging during digital precision printing can be avoided, and the ink can have Better color rendering characteristics. In addition, the digital printing ink with antibacterial ability of the present invention has a pH value between 6 and 8, so it can avoid corrosion of the nozzle of the printing device, and prevent the ink from depositing on the nozzle and causing blockage.

In the digital spray ink with antibacterial ability of the present invention, chitin is used as antibacterial material. The chitin of the present invention has a weight average molecular weight of 200,000 to 300,000. If the weight average molecular weight is less than 200,000, the adhesion of digital inkjet water to the fabric is poor, resulting in poor fastness to washing of the printed fabric. Maintain long-term bacteriostatic effect; conversely, if the weight average molecular weight is greater than 300,000, the dispersion of chitin in the digital printing ink is not good, and it is easy to form precipitates in the ink or fabric, and may even cause nozzle clogging problem. The content of chitin is between 5 wt.% and 10 wt.% based on the total weight of the digital printing ink with antibacterial ability of the present invention. Within this range, chitin can effectively control bacterial growth. When the content of chitin is less than 5 wt.%, the digital printing ink cannot have good antibacterial effect. When the content of chitin is more than 10 wt.%, the solubility of the chitin in the ink will be reduced, and the nozzle will be easily blocked.

In the digital printing ink with antibacterial ability of the present invention, the surfactant includes polyethylene glycol, ethylene oxide, or a combination thereof. The aforementioned polyethylene glycol has, for example, a weight average molecular weight of 400 to 600. The content of the surfactant is between 2 wt.% and 5 wt.% based on the total weight of the digital printing ink with antibacterial ability of the present invention. Within this range, the surfactant can maintain the size stability of the particles (such as chitin, etc.) in the ink. When the content of the surfactant is less than 2 wt.%, the dispersion in the ink cannot be effectively dispersed, and precipitates or aggregates may be generated. When the content of the surfactant is greater than 5 wt.%, the aggregates will lose their coagulation effect due to the excessive repulsion generated by the surfactant.

The digital printing ink with antibacterial ability of the present invention may further contain a coupling agent. The coupling agent is, for example, a polymer having an ethylene oxide side chain. An example of a polymer of an ethylene oxide side chain is Surfynol 465 (trade name, manufactured by Nissin Chemical Industries). The content of the coupling agent is between 0.01 wt.% and 0.06 wt.% based on the total weight of the digital printing ink with antibacterial ability of the present invention. The coupling agent can effectively control the surface tension of the ink, thereby improving the smoothness of the printing and optimizing the ink droplet formation. When the content of the coupling agent is less than 0.01 wt.%, the surface tension of the ink cannot be effectively reduced, so that the smoothness of the printing and the permeability of the ink to the fabric are affected. When the content of the coupling agent is greater than 0.06 wt.%, the surface tension of the digital printing ink is too low, so that the surface of the nozzle of the printing device is easy to contain ink during printing, which affects the state of ink droplets. In other words, the digital printing ink with antibacterial ability of the present invention can have a surface tension of 28 dyne/cm to 40 dyne/cm by further including an appropriate content of the coupling agent, and the appropriate content is, for example, between 0.01 wt.%. to 0.06 wt.%.

The digital spray ink with antibacterial ability of the present invention may further contain a humectant. The humectant is, for example, glycerin. The content of the humectant is between 4 wt.% and 6 wt.% based on the total weight of the digital spray ink with antibacterial ability of the present invention. Within this range, the humectant can ensure that the digital printing ink with bacteriostatic ability of the present invention will not congeal and deposit or block the nozzle during the printing process. When the content of the humectant is less than 4 wt.%, it may not be possible to effectively avoid the condensation of digital printing ink. When the content of the humectant is greater than 6 wt.%, it is easy to cause the drying speed of the ink on the fabric to be too slow, so that the production speed of the overall digital printing process is reduced.

The digital printing ink with antibacterial ability of the present invention may further contain an acid-base adjusting agent. The acid-base regulator is, for example, triethanolamine, phosphate solution, or a combination thereof. Based on the total weight of the digital printing ink with antibacterial ability of the present invention, the content of the acid-base regulator is between 0.1 wt.% and 0.4 wt.%. Within this range, the acid-base regulator can ensure that the pH value of the digital printing ink with antibacterial ability of the present invention is between 6 and 8. When the content of the acid-base regulator is less than 0.1 wt.%, it may not be effective to avoid maintaining the pH of the digital printing ink between 6 and 8. When the content of the acid-base adjusting agent is greater than 0.4 wt.%, the pH of the ink tends to be alkaline, thereby reducing the solubility of chitin to the solvent in the ink, making it easier for the ink to precipitate chitin colloids and block the nozzle.

The digital printing ink with antibacterial ability of the present invention may further include a co-solvent. The co-solvent is, for example, propylene glycol methyl ether. The co-solvent can facilitate the dissolution of chitin in the solvent. The content of the co-solvent is between 4 wt.% and 6 wt.% based on the total weight of the digital printing ink with antibacterial ability of the present invention. When the content of the co-solvent is less than 4wt.%, the solubility of chitin in the ink is not good. When the content of the co-solvent is greater than 6 wt.%, it is easy to make the ink volatilize, and it is not easy to maintain the content of each component in the ink.

In the digital printing ink with antibacterial ability of the present invention, the solvent is, for example, deionized water, but the present invention is not limited thereto.

The digital printing ink with antibacterial ability of the present invention will be tested and evaluated below.

The composition of the digital printing ink of Experimental Example A and Experimental Example B is shown in Table 2. In each experimental example, the moisturizer is glycerin, the co-solvent is propylene glycol methyl ether, the surfactant is polyethylene glycol with a molecular weight of about 600 (trade name PEG 600, manufactured by MERCK), coupling agent It is Surfynol 465 (manufactured by Nissin Chemical Industry), and the acid-base regulator is triethanolamine.

Table 2 Experimental Example A Experimental Example B Chitin 5 wt.% 10 wt.% moisturizer 5 wt.% 5 wt.% Cosolvent 5 wt.% 5 wt.% Surfactant 2.4 wt.% 4.8 wt.% Coupling agent 0.06 wt.% - Acid-base regulator 0.14 wt.% 0.31 wt.% Deionized water 82.4 wt.% 74.89 wt.% Viscosity (cps) 2.24 3.14 Surface tension (dyne/cm) 33.33 31.77 pH value 6.79 6.07 Test nozzle EPSON DX5 EPSON DX5

It can be seen from Table 2 that the inks of Experimental Example A and Experimental Example B have a viscosity between 2 cps and 12 cps, a surface tension between 28 dyne/cm and 40 dyne/cm, and a pH between 6 and 8 Therefore, the inks of Experimental Example A and Experimental Example B have proper fluidity, which can facilitate droplet formation and permeability, and can avoid the problems of ink deposition and nozzle clogging.

>Storage stability test>

After placing the ink of Experimental Example A and Experimental Example B in an oven at 60°C and a refrigerator at 5°C for 15 days, wait for the ink to return to normal temperature to observe whether there is delamination or sediment, and measure the viscosity. According to the test results, the inks of Experimental Example A and Experimental Example B did not delaminate and deposit after being placed at high and low temperatures, and the viscosity change was less than 5%, which means that the inks of Experimental Example A and Experimental Example B are highly stable It can be stored at room temperature for 1 year to 2 years without deterioration.

>Evaluation of fabric color difference>

Print the inks of Experimental Example A and Experimental Example B onto the polyethylene terephthalate fabric, and measure the color space value (CIE Lab value) of the fabric before and after printing with a spectrophotometer (Datacolor 650), It can be seen that the CIE ΔE of the fabric before and after printing with the inks of Experimental Example A and Experimental Example B does not exceed 0.14, that is, the ink of Experimental Example A and Experimental Example B does not affect the color of the fabric.

>Fabric Selectivity>

The inks of Experimental Example 1 to Experimental Example 5 were printed on 100% polyester fiber fabric, polyethylene terephthalate/nylon blended fabric, polyethylene terephthalate/cotton blended fabric, and cotton fabric, All can effectively form precise spray printing patterns on each fabric. That is, the inks of Experimental Example A and Experimental Example B can be applied to various fabrics on the market.

Although the present invention has been disclosed as above with examples, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present invention. The scope of protection of the present invention shall be subject to the scope defined in the appended patent application.

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Claims (6)

A digital inkjet ink for forming an inkjet pattern on a fabric, the digital inkjet ink includes: chitin, having a weight average molecular weight of 200,000 to 300,000; surfactants, including polyethylene glycol, epoxy Ethane or a combination thereof; a humectant, the humectant including glycerin, wherein the content of the humectant is between 4wt.% and 6wt.% based on the total weight of the digital printing ink; and The remaining solvent, wherein the digital inkjet ink has a viscosity of 2 cps to 12 cps and a surface tension of 28 dyne/cm to 40 dyne/cm, and the pH value of the digital inkjet ink is between 6 and 8, and wherein Based on the total weight of the digital printing ink, the content of the chitin is between 5wt.% and 10wt.%, and the content of the surfactant is between 2wt.% and 5wt.%. The digital printing ink as described in item 1 of the patent application scope further includes an acid-base adjusting agent, and the acid-base adjusting agent includes triethanolamine, a phosphate solution or a combination thereof, wherein the total weight of the digital printing ink Calculated, the content of the acid-base regulator is between 0.1 wt.% and 0.4 wt.%. The digital printing ink as described in item 1 of the patent application scope further includes a coupling agent, and the coupling agent includes a polymer having an ethylene oxide side chain, wherein based on the total weight of the digital printing ink, the The content of the coupling agent is between 0.01 wt.% and 0.06 wt%. The digital printing ink as described in item 1 of the patent application scope further includes a co-solvent, and the co-solvent includes propylene glycol methyl ether, wherein the content of the co-solvent is based on the total weight of the digital printing ink 4wt.% to 6wt.%. The digital printing ink as described in item 1 of the patent application scope, wherein the solvent includes deionized water. The digital printing ink as described in item 1 of the patent application range, wherein the polyethylene glycol has a weight average molecular weight of 400 to 600.