Aqueous ink compositon and method for thereof

Abstract

The present invention provides an aqueous ink composition and a method for manufacturing the same. The ink composition maintains stable performance even at a high temperature of 135°C, making it suitable for printing on retort food packaging, and provides high adhesion to polyester and / or nylon films, thereby improving the durability of the printed material.

Description

Technology Field

[0001] The present invention relates to an aqueous ink composition and a method for manufacturing the same. Background Technology

[0002] Retort foods are convenience foods that can be preserved for a long time by being sterilized under high temperature and high pressure, and demand for them has recently increased significantly. The retort process is generally carried out at 121°C for 30 minutes or at 135°C for 10 minutes, and special packaging materials capable of withstanding these high-temperature conditions are required.

[0003] Oil-based inks have primarily been used for printing on conventional retort food packaging. While oil-based inks were preferred due to their stability under high-temperature conditions and excellent adhesion, they presented problems such as the atmospheric release of harmful chemicals and health threats caused by residual solvents.

[0004] Although water-based inks have the advantages of being environmentally friendly and less harmful to the human body, conventional water-based inks could not be applied to retort food packaging materials due to poor adhesion and insufficient post-processability under the high-temperature conditions of the retort process.

[0005] With the surge in demand for retort foods following the COVID-19 pandemic, the use of oil-based inks has increased, raising concerns about environmental pollution and health risks. Consequently, the development of eco-friendly and safe water-based inks applicable to retort food packaging has emerged as an urgent task. The problem to be solved

[0006] The present application aims to develop an aqueous ink suitable for a retort process and to provide a new ink composition that is applicable to both gravure printing and flexographic printing and can be used without a curing agent.

[0007] The technical problems of the present application are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0008] One aspect of the present application provides an aqueous ink composition comprising a mixed resin including aqueous acrylic, aqueous urethane, and rosin resin, water, ethanol, a dispersant, and a pigment, wherein the mixed resin comprises aqueous acrylic, aqueous urethane, and rosin resin in a weight ratio of 2:4 to 7:2.

[0009] Another aspect of the present application provides a method for preparing an aqueous ink composition for printing on the surface of a film, comprising the steps of: mixing a dispersion resin, water, a dispersant, and a pigment; dispersing the mixture to prepare a base; and adding an aqueous urethane, an aqueous acrylic, a rosin resin, and ethanol to the base and stirring; wherein the dispersion resin is an aqueous acrylic, and the aqueous urethane, aqueous acrylic, and rosin resin are included in a weight ratio of 2:4 to 7:2 based on the total weight of the aqueous ink composition. Effects of the invention

[0010] According to one embodiment of the present invention, the aqueous ink applicable to the retort of the present invention does not contain an organic solvent, so the safety of the food packaging material can be improved by minimizing the risk caused by residual solvent.

[0011] At the same time, it can be applied to both gravure printing and flexo printing, allowing it to accommodate various printing methods.

[0012] In addition, since the use of a curing agent is unnecessary, it can reduce ink waste and increase production efficiency. Furthermore, it can be suitable for printing packaging for retort foods by maintaining stable performance even at high temperatures of 135°C, and can improve the durability of printed materials by providing high adhesion to polyester and / or nylon films. Specific details for implementing the invention

[0013] The structural or functional descriptions of the embodiments disclosed in this specification are merely illustrative for the purpose of explaining embodiments according to the technical concept of this application. Furthermore, embodiments according to the technical concept of this application may be implemented in various forms other than those disclosed in this specification. Additionally, the technical concept of this application is not to be interpreted as being limited to the embodiments described in this specification.

[0014] The present invention will be described in detail below. Prior to this, terms or words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. Accordingly, the configurations described in the embodiments described in this specification are merely one preferred embodiment of the present invention and do not represent all of the technical spirit of the present invention; therefore, it should be understood that various equivalents and modifications capable of replacing them may exist at the time of filing this application.

[0015] One aspect of the present invention provides an aqueous ink composition for printing on the surface of a film.

[0016] The above aqueous ink composition may include a mixed resin, water, ethanol, a dispersant, and a pigment.

[0017] The above mixed resin may include water-based urethane, water-based acrylic, and rosin resins.

[0018] Aqueous urethane may include a polymer in which the main chain contains -NHCOO- repeating structural units and is formed by the polymerization of isocyanate (monomer) and hydroxyl compound, and aqueous acrylic may include acrylic monomers such as acrylic acid and methyl methacrylate.

[0019] Rosin resin is a natural resin extracted from the resin of pine trees, and has abietic acid as its main component, and may include neobietic acid, lepopimaric acid, hydrobietic acid, pimaric acid, dexonic acid, etc. The rosin resin of the present invention may include disproportionate rosin, hydrogenated rosin, reinforced rosin, rosin ester, rosin phenol, etc.

[0020] By using the above mixed resin, stable performance can be maintained even at a high temperature of 135°C, making it suitable for printing packages of retort foods, and in particular, high adhesion to polyester and / or nylon films can be provided to improve the durability of the printed material.

[0021] Specifically, the above mixed resin may include water-based urethane, water-based acrylic, and rosin resins in a weight ratio of 2:4 to 8:1 to 2, and, for example, may include them in a weight ratio of 2:5 to 7:1 to 2.

[0022] The above mixed resin may comprise 10 to 20 weight% acrylic resin, 50 to 70 weight% urethane resin, and 10 to 20 weight% rosin resin based on the total weight of the mixed resin, and, for example, may comprise 15 to 20 weight% acrylic resin, 60 to 70 weight% urethane resin, and 15 to 20 weight% rosin resin.

[0023] Within the above range, the ink exhibits excellent adhesion to polyester and / or nylon films and can exhibit heat resistance suitable for retort food packaging.

[0024] In addition, the mixture may contain 10 to 30 weight percent based on the total weight of the aqueous ink composition, for example, 20 to 30 weight percent, and within the above range, heat resistance and adhesion may be excellent.

[0025] In one embodiment of the present invention, the aqueous ink composition may include a solvent, and water may be used as the solvent. It may be included in an amount of 10 to 40 weight% based on the total weight of the aqueous ink composition, and specifically in an amount of 20 to 30 weight%.

[0026] Ethanol may be used as another solvent, and unlike toluene and others that have been conventionally used, ethanol is not a toxic substance and does not remain on the packaging but can volatilize as it dries during the printing process. The ethanol may be included in an amount of 20 to 30 weight percent based on the total weight of the aqueous ink composition.

[0027] At this time, the weight ratio of the mixed resin : water and ethanol included in the aqueous ink composition may be 1:2 to 4, and specifically 1:2 to 3. Within the above range, high adhesion to polyester and / or nylon films can be provided, thereby improving the durability of the printed material.

[0028] The dispersant acts to disperse the pigment, prevents re-aggregation of the pigment, and maintains dispersibility. It may be included in an amount of 2 to 20 weight% based on the total weight of the aqueous ink composition, specifically 2 to 10 weight%, for example, 2 to 5 weight%.

[0029] Pigments are components that serve as coloring agents for water-based inks, and pigments commonly used in the industry may be used. Specifically, inorganic pigments such as carbon black and metal oxides, and organic pigments such as azo pigments, diazo pigments, phthalocyanine pigments, perylene pigments, perinone pigments, thioindigo pigments, anthraquinone pigments, and quinophthalone pigments may be used. In a preferred embodiment of the present invention, the pigment is a pigment with high lightfastness, and more specifically, it is preferable to use a pigment with a lightfastness of grade 7 or higher.

[0030] For example, red48:1, 49:1, red 146, red53:1, red254, red 57:1, Yellow14, yellow74, yellow83, yellow13, Blue 15:3, Blue 15:4, Tio2, black7, etc. can be used.

[0031] Colored pigments and white pigments can be mixed and used in a weight ratio of 1:1.5 to 1:3, and preferably in a ratio of 1:1.8 to 1:2.1.

[0032] To improve clarity and print quality, the pigment may be included in an amount of 8 to 20 weight percent, for example, 8 to 10 weight percent, based on the total weight of the water-based ink composition. Within this range, the heat resistance may be 135°C or higher, and discoloration may be minimized.

[0033] One or more additives used in the relevant technical field may be further included within a range that does not impair the physical properties of the present invention. The additives include wetting agents, slip agents, preservatives, thickeners, etc., but in one embodiment, a heat-resistant additive may be used and may be included in an amount of 0.001 to 3 weight% based on the total weight of the aqueous ink composition.

[0034] As described above, an aqueous ink composition comprising a mixed resin; water; ethanol; a dispersant and a pigment according to one embodiment of the present invention has excellent heat resistance and adhesion, and can provide high adhesion to polyester and / or nylon films even without a curing agent, and can provide an ink applicable to both gravure printing and flexographic printing.

[0035] According to another aspect of the present invention, a method for preparing an aqueous ink composition comprises a mixing step, a base preparation step, and a stirring step.

[0036] Meanwhile, all components of the aforementioned aqueous ink composition can be applied to a method for manufacturing an aqueous ink composition.

[0037] The mixing step is a step of mixing a dispersion resin, water, a dispersant, and a pigment, which means mixing the above components in the content of the aforementioned aqueous ink composition. At this time, the dispersion resin may be an aqueous acrylic, and may comprise 1 to 10 weight% of dispersion resin, 10 to 40 weight% of water, 2 to 20 weight% of dispersant, and 8 to 20 weight% of pigment based on the total weight of the aqueous ink composition.

[0038] In addition, a base can be prepared by dispersing the mixture prepared in the above mixing step. At this time, additives may be added, and the particles may be ground to 5 μm or less using a bead mill machine so that the additives are mixed into the molecular pores of the water-based acrylic, thereby improving heat resistance. Through grinding, the particle size of pigments, etc., can be controlled and fine particles formed to improve the color, transparency, and printing characteristics of the ink.

[0039] In addition, water-based urethane, water-based acrylic, rosin resin, and ethanol may be added to the base and stirred. At this time, the total weight of the water-based urethane, water-based acrylic, and rosin resin may be 10 to 20 weight% based on the total weight of the water-based ink composition, and the ethanol may be 20 to 30 weight%.

[0040] Stirring enhances the stability of the mixture and helps the binder mix well with pigments to form an appropriate texture, while the addition of resin contributes to ink stabilization and ensures consistent characteristics are maintained during the printing process. The addition of ethanol can help disperse fine particles, such as pigments, more effectively; it can be used to induce better dispersion when fine particles do not mix well with water. Additionally, ethanol can increase the drying speed of the ink.

[0041] The present invention will be further described below through examples, but it is obvious that the present invention is not limited by the following examples.

[0043] Preparation Example: Preparation of mixed resin

[0044] Each resin was prepared according to the composition ratios in Table 1 below. In the table below, each component is in weight% relative to the total weight of the mixed resin, and the mixed resin was prepared by mixing each resin and used in Examples 1 and 2 and Comparative Examples 1 to 4.

[0045] (Unit: weight%) Preparation Example 1 Preparation Example 2 Preparation Example 3 Preparation Example 4 Preparation Example 5 Preparation Example 6 Water-based acrylic 18 20 10 10 30 10 Water-based urethane 70 60 60 40 60 60 Rosin Suzy 12 20 10 10 10 30

[0046] Examples and Comparative Examples: Preparation of Aqueous Ink Compositions

[0047] Example 1

[0048] An ink composition was prepared containing 30% of the mixed resin of Preparation Example 1 based on the total weight of the aqueous ink composition. Of this, half of the aqueous acrylic in Table 1 was used as a dispersion resin and half was used as a mixed resin.

[0049] Specifically, 2.7 wt% of water, which is half of the aqueous acrylic of Preparation Example 1, 30 wt% of water, 3 wt% of a dispersant, 8 wt% of a pigment, and 2 wt% of an additive were mixed, and a base was prepared by finely grinding the particles to 5 μm or less using a bead mill machine.

[0050] Subsequently, the resulting base was mixed with 2.7 wt% water-based acrylic, 21 wt% water-based urethane, and 3.6 wt% rosin resin, and 30 wt% ethanol was added and mixed with a stirrer to prepare the water-based ink composition of Example 1.

[0052] Example 2

[0053] A water-based ink composition was prepared in the same manner as in Example 1, except that in Preparation Example 2, 3 wt% of water-based acrylic was used as the dispersion resin, and 3 wt% of water-based acrylic, 18 wt% of water-based urethane, and 6 wt% of water-based urethane were used as the mixed resin.

[0055] Comparative Example 1

[0056] A water-based ink composition was prepared in the same manner as in Example 1, except that in Preparation Example 3, 1.5 wt% of water-based acrylic was used as the dispersion resin, and 1.5 wt% of water-based acrylic, 18 wt% of water-based urethane, and 3 wt% of water-based urethane were used as the mixed resin.

[0058] Comparative Example 2

[0059] A water-based ink composition was prepared in the same manner as in Example 1, except that in Preparation Example 4, 1.5 wt% of water-based acrylic was used as the dispersion resin, and 1.5 wt% of water-based acrylic, 12 wt% of water-based urethane, and 3 wt% of water-based urethane were used as the mixed resin.

[0061] Comparative Example 3

[0062] A water-based ink composition was prepared in the same manner as in Example 1, except that in Preparation Example 5, 4.5 wt% of water-based acrylic was used as the dispersion resin, and 45 wt% of water-based acrylic, 18 wt% of water-based urethane, and 3 wt% of water-based urethane were used as the mixed resin.

[0064] Comparative Example 4

[0065] A water-based ink composition was prepared in the same manner as in Example 1, except that in Preparation Example 6, 1.5 wt% of water-based acrylic was used as the dispersion resin, and 1.5 wt% of water-based acrylic, 12 wt% of water-based urethane, and 9 wt% of water-based urethane were used as the mixed resin.

[0067] Comparative Example 5

[0068] An aqueous ink composition was prepared in the same manner as in Example 1, except that toluene was used as the solvent in Preparation Example 2.

[0070] Experimental Example

[0071] Experimental Example 1: Printability Evaluation

[0072] The aqueous ink compositions prepared in Examples 1 and 2 and Comparative Examples 1 to 5 were printed on PET, nylon, and PET / nylon films, respectively, and then the color development power (pigment dispersibility) was evaluated.

[0073] At this time, the color development was evaluated by printing a flower shape using the aqueous ink compositions of the above examples and comparative examples, and then having 20 men and 20 women with the same visual acuity (0.8 to 1.0) evaluate it using a 5-point scale, and the average value is shown in Table 2 below.

[0074] In the above color development evaluation, the closer the value is to 5, the better the color development and the less bleeding or clumping there is, meaning that the dispersion of the pigment is excellent.

[0075] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 PET 4.7 4.6 2.9 3.1 3.7 3.5 3.7 nylon 4.8 4.5 1.3 3.5 3.2 3.1 3.5 PET / Nylon 4.7 4.6 2.3 3.3 3.5 3.4 3.6

[0076] As can be seen in Table 2 above, it was confirmed that when the aqueous ink compositions prepared in Examples 1 and 2 were used, there was less clumping and better color development compared to when the ink compositions prepared in Comparative Examples 1 to 5 were used.

[0078] Experimental Example 2: Off-odor Evaluation

[0079] After printing the aqueous ink compositions prepared in Examples 1 and 2 and Comparative Examples 1 to 5 onto PET, nylon, and PET / nylon films, respectively, the presence of an odor or unpleasant smell was evaluated using a 5-point scale, and the average values ​​are shown in Table 3 below. A score closer to 5 indicates less odor or unpleasant smell.

[0080] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Off-flavor 4.1 4.2 4.3 4.0 4.4 4.3 1.8

[0081] As can be seen in Table 2 above, it was confirmed that in the case of Comparative Example 5, an unpleasant odor of the oily solvent occurred compared to the water-based ink composition.

[0083] Experimental Example 3: Evaluation of Adhesion Strength

[0084] The aqueous ink compositions prepared in Examples 1 and 2 and Comparative Examples 1 to 5 were each printed on a PET / nylon film, and the adhesive strength was evaluated.

[0085] The tensile shear adhesive strength test method was used, and the adhesive strength was evaluated according to ASTM D3163 by applying an ink composition approximately 1 mm thick between two substrates, drying it, and applying a load outward from both ends (unit: g / mm).

[0086] temperature Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 120°C 450 443 393 412 402 405 301 135°C 312 307 286 275 273 276 276

[0088] As can be seen in Table 4 above, the ink compositions prepared in Examples 1 and 2 were found to be suitable for printing retort food packages without a curing agent, as they exhibited significantly superior print film strength at 135°C compared to Comparative Examples 1 to 5.

[0089] Foregoing, specific parts of the contents of this application have been described in detail. It will be apparent to those skilled in the art that such specific descriptions are merely preferred embodiments and do not limit the scope of this application. Accordingly, the actual scope of this application is defined by the appended claims and their equivalents.

Claims

Claim 1 A water-based ink composition for printing on the surface of a film, comprising a mixed resin including water-based acrylic, water-based urethane, and rosin resin, water, ethanol, a dispersant, and a pigment, wherein the mixed resin comprises water-based acrylic, water-based urethane, and rosin resin in a weight ratio of 2:4 to 8:1 to 2. Claim 2 A water-based ink composition according to claim 1, comprising 10 to 20 weight% water-based acrylic, 50 to 70 weight% water-based urethane, and 10 to 20 weight% rosin resin based on the total weight of the mixed resin. Claim 3 An aqueous ink composition according to claim 1, comprising 10 to 30 weight% of mixed resin, 10 to 40 weight% of water, 20 to 30 weight% of ethanol, 2 to 20 weight% of dispersant, and 8 to 20 weight% of pigment based on the total weight of the aqueous ink composition. Claim 4 In claim 1, the aqueous ink composition is an aqueous ink composition that does not contain a curing agent. Claim 5 An aqueous ink composition according to claim 1, further comprising 0.001 to 3 weight percent of a heat-resistant additive based on the total weight of the aqueous ink composition. Claim 6 In claim 1, the above-mentioned printing is a water-based ink composition in which gravure or flexographic printing is used. Claim 7 In claim 1, the film is an aqueous ink composition comprising polyester and nylon. Claim 8 A method for preparing a water-based ink composition for printing on the surface of a film, comprising the steps of: mixing a dispersion resin, water, a dispersant, and a pigment; dispersing the mixture to prepare a base; and adding a water-based urethane, a water-based acrylic, a rosin resin, and ethanol to the base and stirring. Claim 9 In claim 8, the method for manufacturing a water-based ink composition in which the dispersion resin is a water-based acrylic. Claim 10 A method for manufacturing an aqueous ink composition according to claim 9, comprising aqueous urethane, aqueous acrylic, and rosin resin in a weight ratio of 2:4 to 7:2 based on the total weight of the aqueous ink composition.

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