KR102374579B1 - Ink composition for aqueous flexographic printing and process for preparing the same - Google Patents

Abstract

The present invention relates to an ink composition for water-based flexographic printing and a manufacturing method thereof, and more specifically, to an ink composition for flexographic printing which does not comprise a harmful material and thus is eco-friendly for the environment and human body and a manufacturing method thereof. The ink composition for flexographic printing according to the present invention has excellent whiteness, scratch resistance, and adhesive strength, reduces the use of an organic solvent through a high-concentration and low-viscosity ink, and reduces energy and exhaust gases during drying. In addition, the ink composition for flexographic printing can increase the seal strength of a food packaging material and improve workability, thereby providing various economic feasibility.

Description

Ink composition for aqueous flexographic printing and method for preparing the same

The present invention relates to an aqueous flexographic ink composition and a method for manufacturing the same, and more particularly, to an ink composition for flexographic printing that does not contain harmful substances and is environmentally friendly to the environment and human body, and a method for manufacturing the same.

The use of packaging materials to protect food is increasing, and food packaging materials need not only protect the contents, but also increase the advertising effect externally, and internally, it is necessary to be harmless to the human body even in direct contact with food.

Recently, as the number of consumers pursuing natural, organic, eco-friendly, etc. increases, packaging materials having various functionalities are being developed in the food packaging material field by reflecting this trend.

These packaging materials are generally manufactured through gravure printing, and the gravure printing is toluene, methyl ethyl ketone (MethylEthyl Ketone; MEK), ethyl acetate (Ethyl Acetate; EA), xylene, ethyl cellosolve ( Ink containing an organic solvent such as Ethyl Cellosolve (EC) is used.

These organic solvents are all volatile organic compounds (VOCs), and are known to have harmful effects on the human body or the environment as well as odors.

Specifically, these organic solvents are released into the atmosphere in the drying process of printing and become a source of air pollution, are directly exposed to workers and are harmful to the human body, and carry a risk of fire during the printing operation. In particular, if such an organic solvent remains in the packaging material, there is a problem that a hygienic print cannot be obtained and it is harmful to the human body.

On the other hand, the flexographic printing (Flexographic printing) method belongs to the letterpress method, but is often used together with gravure printing in the field of packaging printing and is handled separately. In this method, a rubber or photosensitive resin plate, which is softer than a normal type plate, is used as the plate material, and the ink has a low viscosity similar to that of gravure ink, and a solvent-based or water-based ink is used.

Flexographic printing has many merits such as partial exchange of plates because plate making is simple, low cost, and easy to duplicate compared to other printing, especially gravure printing. Do. Since the ink film is thin and water or alcohol is used, the residual solvent is small or harmless, so a clean package working environment can be realized.

Flexographic printing uses low-viscosity and high-density ink, and low-viscosity can accurately reproduce images and improves work aptitude due to good ink circulation. less impact of degradation.

In recent years, water-based ink has been used even for non-absorbable printed materials such as films and aluminum foils due to the need for safety against fire, sanitary work environment, and reduction of residual solvents in printed matter. In addition, it is less affected by temperature and humidity in the printing process and performs stable printing even under relatively wide printing conditions.

However, flexographic printing is different from gravure printing, and since rubber or photosensitive resin is used for the printing plate material, there are restrictions on the ink solvent and the binder used. Therefore, there is a continuous demand to improve the physical properties of the flexographic ink because it must have the functions of adjusting the viscosity and fluidity of the ink, stabilizing the dispersion system, dispersing the pigment, and fixing the pigment.

Korea Publication No. 10-2021-0042200 (April 19, 2021) Korea Registration No. 10-2160953 (September 23, 2020) Korea Registration No. 10-2068154 (January 14, 2020)

Accordingly, the present inventors solve the problems of the prior art accompanying the flexographic printing ink, have excellent whiteness, scratch resistance and adhesive strength, and reduce the use of organic solvents through high-concentration and low-viscosity inks, reduce energy and exhaust gas during drying, As a result of intensive research to provide a flexo ink composition with improved seal strength and workability of food packaging, an ink composition prepared using an anionic polyurethane resin (PUD) as a main component as described below meets these requirements. It was confirmed that it can be satisfied and came to complete the present invention.

Accordingly, an object of the present invention is to solve the problems of the prior art accompanying the flexographic printing ink, to have excellent whiteness, scratch resistance and adhesive strength, and to reduce the use of organic solvents through high-concentration and low-viscosity inks, energy and An object of the present invention is to provide a flexographic ink composition having improved exhaust gas reduction, increased seal strength of food packaging materials, and improved workability.

The object of the present invention as described above, in one aspect

A pigment, an anionic polyurethane resin dispersion, water and additives as a diluting solvent, and the anionic polyurethane resin dispersion is 5-10 wt% of aromatic diisocyanate, 5-10 wt% of aliphatic diisocyanate, modified silicone diol 5-20 wt%, low molecular weight polyol 3-5 wt%, polyurethane urea prepolymer 1-2 wt%, other additives 1-3 wt%, dimethylolpropionic acid 1-2 wt%, amines 2-5 wt% and water 60 It can be achieved by an aqueous flexographic ink composition and a method for preparing the same, characterized in that it is prepared from a composition containing ~70% by weight.

Therefore, the ink composition for flexographic printing according to the present invention has excellent whiteness, scratch resistance and adhesive strength, and reduces the use of organic solvents through high-concentration and low-viscosity inks, reduces energy and exhaust gas during drying, increases seal strength of food packaging materials, and Since workability can be improved, it provides various economic feasibility.

1 is a manufacturing process diagram of an ink composition for aqueous flexographic printing according to the present invention.
2 is a view for explaining the manufacturing process of the anionic polyurethane resin according to the present invention.

The present invention, in one aspect,

A pigment, an anionic polyurethane resin dispersion, water and additives as a diluting solvent, and the anionic polyurethane resin dispersion is 5-10 wt% of aromatic diisocyanate, 5-10 wt% of aliphatic diisocyanate, modified silicone diol 5-20 wt%, low molecular weight polyol 3-5 wt%, polyurethane urea prepolymer 1-2 wt%, other additives 1-3 wt%, dimethylolpropionic acid 1-2 wt%, amines 2-5 wt% and water 60 It provides an aqueous flexographic ink composition and a method for preparing the same, characterized in that it is prepared from a composition containing ~70% by weight.

Hereinafter, with reference to the accompanying drawings with respect to the aqueous flexographic ink composition and the manufacturing method according to the present invention will be described in more detail.

The terms or words used in the present specification and claims are not to be construed as limited in their ordinary or dictionary meanings, and on the principle that the inventor can appropriately define the concept of the term in order to best describe his invention. It should be interpreted as meaning and concept consistent with the technical idea of the present invention. Therefore, since the embodiments described herein and the configurations shown in the drawings are only the most preferred embodiment of the present invention, it is understood that there may be various equivalents and modifications that can be substituted for them at the time of the present application. shall.

In the present invention, the aqueous flexographic printing ink composition is expressed in parts by weight or weight%, and the sum of individual components may include an inoperable part exceeding 100% by weight according to the calculation formula, but such an excess or infeasible part It is obvious that is not included in the scope of the present invention, and in particular in the claims, corrections to clarify this, for example, corrections that add proviso clauses such as excluding the range exceeding 100% by weight from the scope of the present invention It is self-evident that only clarifies an ambiguous description, and does not affect the nature or scope of the present invention.

The water-based flexographic printing ink composition in the present invention does not use any VOC regulated substances, and has excellent whiteness, scratch resistance and adhesive strength. Since it is possible to reduce and increase the seal strength of the food packaging material, various advantages such as improved workability can be provided.

The aqueous flexographic printing ink composition according to the present invention comprises 18 to 40% by weight of a pigment, 25 to 50% by weight of an anionic polyurethane resin dispersion, 26 to 50.5% by weight of water, and 3.40 to 10.1% by weight of additives. It may be desirable to be prepared.

The manufacturing method of the aqueous flexographic printing ink composition of the present invention is not particularly limited, but, for example, as shown in FIG. 1, may be prepared by the following method. 1 is a manufacturing process diagram of an ink composition for aqueous flexographic printing according to the present invention.

First, the pigment, the anionic polyurethane resin dispersion, water, and additives as necessary are mixed in a predetermined ratio, and then pre-mixing is performed to cover the surface of the pigment with water. Subsequently, in the dispersing step, an adjustment step of dispersing the pigment into fine particles and, if necessary, imparting a function to the ink may be included. As a result, the completed ink composition undergoes a quality inspection process of inspecting physical properties such as adhesion, viscosity, and gloss of the ink, and is then packaged in a predetermined unit and finally shipped.

The pigment included in the ink composition of the present invention is a material for expressing color, and may include an organic pigment, an inorganic pigment, and the like. The pigment is not particularly limited, and a commonly used pigment may be suitably used in the present invention.

Specifically, for example, azo-lake, insoluble azo, condensed azo, phthalocyanide, titanium oxide, carbon black, calcium carbonate, aluminum powder, bronze powder, Solvent Dye, etc. It can be appropriately selected and used according to the quality.

The anionic polyurethane resin dispersion is aromatic diisocyanate 5-10 wt%, aliphatic diisocyanate 5-10 wt%, modified silicone diol 5-20 wt%, low molecular weight polyol 3-5 wt%, polyurethane urea prepolymer 1- It is preferably prepared from a composition containing 2% by weight, 1 to 3% by weight of other additives, 1 to 2% by weight of dimethylolpropionic acid, 2 to 5% by weight of amines, and 60 to 70% by weight of water.

The anionic polyurethane resin dispersion serves as a binder for adhering the flexographic ink composition to the printed material, and improves adhesion between the ink and the printed material, and has excellent re-solubility, color development, and gloss of flexographic printing. to improve the print quality.

For example, the ink composition for flexographic printing of the present invention is printed on the surface of an OPP film, a PET film, a nylon film, or an aluminum foil, and the anionic polyurethane resin dispersion has excellent adhesion to such various materials. can be provided, and can be preferably used.

In addition, the anionic polyurethane resin dispersion has little residual solvent and has excellent film performance such as lamination processability, chemical resistance (edible oil, vinegar, fragrance), and retort resistance. (Boil) and high-pressure retort (Hi-Retort) products can be suitably used for packaging.

The aromatic diisocyanate is a component for improving chemical resistance, and 2,4- or 2,6-toluene diisocyanate may be preferably used.

The aliphatic diisocyanate is an aliphatic component that improves water resistance and adhesion, and includes hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) or bis(4-isocyanatocyclohexyl)methane (H ₁₂ -MDI). It can be used preferably.

Preferably, the aromatic diisocyanate and the aliphatic diisocyanate are used in a weight ratio of 1:0.9 to 1.1, more preferably in a weight ratio of 1:1.

By using the aromatic diisocyanate and the aliphatic diisocyanate within the above range, aggregation or gelation due to rapid reactivity with water molecules during dispersion in water is prevented, thereby improving particle stability of the dispersion and maintaining an appropriate viscosity.

The modified silicone diol provides high slip properties, prevents sticking to work rollers, etc., and interferes with the interaction between hydrophilic chains on the surface of particles to increase dispersibility and stability and lower viscosity. Monodicarbinol terminated Polydimethylsiloxane polyol (Monodicarbinol terminated polydimetylsiloxane) can be preferably used. FMDA11 is known as a product name.

The low molecular weight polyol is a component for controlling the NCO ratio, and is represented by the following formula (1) and has a weight average molecular weight of 1,000 to 2,000.

In the formula, n is an integer of 8 to 20.

As the low molecular weight polyol, poly(tetramethylene oxide)glycol {(poly(tetra methylene oxide)glycol, hereinafter PTMG, MW=2000, Dow Chemical Co., Ltd.}) may be used.

The dimethylolpropionic acid (DMPA, dimethylolpropionic acid) is used as a monomer containing a carboxyl group (-COOH).

The polyurethane urea prepolymer is a component that enhances tensile strength, has an isocyanate terminus, and contains a diisocyanate component (eg, IPDI) in the presence of a water-soluble volatile organic solvent (eg, acetone) at a temperature of room temperature to 100°C. : Isophorone diisocyanate, HDI: It can be prepared by reacting hexamethylene diisocyanate), a monomer containing a carboxyl group (DMPA), and a polyol component (eg, polyester diol, 1,4-butanediol).

The polyol component provides anionic carboxyl groups and cationic sulfonate groups to the dispersed polyurethaneurea polymer.

Preferred polyol components are polyester diols, ie any compounds containing -C(=O)-O- groups. Examples include polyesters prepared from poly(1,3-butanediol adipate), caprolactone, acid-containing polyols, hexane diol, adipic acid and isophthalic acid, such as hexane adipate isophthalate polyester, hexane diol neo pentyl glycol adipic acid polyester diols such as Piothane 67-3000 HAI, Piotan 67-500 HAI, Piotan 67-3000 HNA (Panolam Industries) and Piothane 67-1000 HNA; and propylene glycol maleic anhydride adipic acid polyester diols such as piotan 50-1000 PMA; and hexane diol neopentyl glycol fumaric acid polyester diol such as Piotan 67-500 HNF.

The amines may be selected from one or two selected from the group consisting of hydrazine hydrate, ethylenediamine, isophoronediamine, and diethylenetriamine.

The other additives are n-ethyl-2-pyrrolidone cosolvent, N-methyl-2-pyrrolidone dissolution promoter, tin octoate, dibutyltin dilaurate (DBTL), tetrabutyl titanate A metal catalyst selected from tetrabutyl titanate (TNBT), dibutyltin dilaurylate, a bismuth compound (eg bismuth carboxylate), or a zinc compound and a neutralizing agent that is triethylamine or dimethylethanolamine may include

2 is a view for explaining the manufacturing process of the anionic polyurethane dispersion according to the present invention. The process largely comprises DMPA dissolution step, diisocyanate and catalyst addition step, polymerization step and chain extension step. Hereinafter, each individual step will be described in detail.

a) DMPA dissolution step

For a uniform reaction, a low molecular weight polyol, modified silicone diol, dimethylolpropionic acid (DMPA), and a cosolvent are put into a reactor equipped with an impeller, and the DMPA is completely dissolved while stirring at 70 to 75° C. for about 20 minutes.

In this case, as the cosolvent, n-ethyl-2-pyrrolidone (NEP, n-ethyl-2-pyrrolidone) may be preferably used, and N-methyl-2-pyrrolidone, which is a hydrophilic solvent, to promote the dissolution of DMPA. It may be preferable to add (NMP) in an amount of 5% or less of the total solute.

b) adding diisocyanate and catalyst

Then, while maintaining the temperature of the reactor at 60 ℃, diisocyanate and catalyst are simultaneously added and reacted for 3 to 4 hours to synthesize a polyurethane prepolymer.

It is good to use the diisocyanate in an amount of 5-10 wt% of aromatic diisocyanate and 5-10 wt% of aliphatic diisocyanate based on the total reactant to improve chemical resistance, water resistance and adhesion of the ink composition.

It is preferable to use the aromatic diisocyanate and the aliphatic diisocyanate in a weight ratio of 1: 0.9 to 1.1, and more preferably, use it in a weight ratio of 1:1.

The catalyst may use an organotin compound, dibutyltin dilaurate (DBTL), tetrabutyl titanate (TNBT, tetrabutyl titanate), a bismuth compound, or a zinc compound. It is preferable to select and use it. It may be desirable to use the organotin compound within 3% by weight of the reaction mixture.

The progress of the reaction can be confirmed by increasing the viscosity, and the end point of the reaction can be confirmed by the dibutylamine (DBA) retrostatic method when the NCO content reaches the theoretical value.

c) neutralization step

Polyurethane urea prepolymer and a neutralizing agent are added to the reaction mixture to neutralize the prepolymer for 20 to 30 minutes at a temperature between 75 to 80° C., and then distilled water is added at a constant speed while strongly stirring to prepare an ionic prepolymer aqueous product.

As a neutralizing agent, it is recommended to use either triethylamine (TEA, Triethylamine) or dimethylethanolamine (DMEA, Dimethylethanolamime).

d) chain extension step

After cooling the aqueous ionic prepolymer to 10 ℃, distilled water in which ethylenediamine (EDA) as a chain extender and amines are dissolved is added at a constant rate to induce branch extension reaction of the prepolymer in the dispersed particles. A polyurethane dispersion is prepared.

The amines preferably used in this step are hydrazine hydrate (HH, Hydrazine Hydrate), ethylenediamine (EDA, Ethylene diamine), isophorone diamine (IPDA, isophorone diamine), a group consisting of diethylene triamine (DETA, Diethylene triamine) one or two selected from

The preparation method includes 5 to 10% by weight of an aromatic diisocyanate, 5 to 10% by weight of an aliphatic diisocyanate, 10 to 20% by weight of a modified silicone diol, 3 to 5% by weight of a low molecular weight polyol, and 1 to 2% by weight of a polyurethane urea prepolymer as a reactant. , other additives 1 to 3% by weight, dimethylolpropionic acid 1 to 2% by weight, amines 2 to 5% by weight, and water 60 to 70% by weight, until the NCO group of diisocyanate reaches the theoretical value. By reacting and preparing an anionic polyurethane resin dispersion using aromatic diisocyanate and aliphatic diisocyanate in a weight ratio of 1:0.9 to 1.1, relatively excellent physical properties can be obtained without a separate curing agent, and when dispersed in water, The rapid reactivity can improve particle stability due to agglomeration or gelation.

As an additive of the aqueous flexographic printing ink composition of the present invention, an anti-blocking agent, a dispersant, an anti-foaming agent, an antioxidant, an adhesion reinforcing agent, a film reinforcing agent in order to assist the ink flow, surface tension, scratch resistance, anti-static, slurry consistency and gloss properties. , additives including antistatic agents and the like may be included.

The additive may be included in an amount of 3.4 to 10.1% by weight based on the total weight of the composition.

In a specific embodiment, the additive comprises 0.1 to 1 wt% of an antiblocking agent, 1 to 3 wt% of a dispersant, 0.1 to 2 wt% of an antioxidant, 1 to 5 wt% of an adhesion reinforcing agent, 0.3 to 1 wt% of a film reinforcing agent, and an antistatic agent It may be more preferable to include 0.1 to 1% by weight.

The anti-blocking agent can be suitably applied in the present invention as long as it is a component for preventing blocking that sticks to each other and interferes with work. For example, but not limited to these, wax, calcium carbonate CaCO ₃ , talc (Talc), silica (SiO ₂ ), aluminum silicate, silicon beads, and the like. These antiblocking agents can be used independently, of course, 2 or more types can also be mixed and used for it.

The dispersant is generally used as a partially neutralized alkylammonium salt solution of polydimethylsiloxane and polycarboxylic acid or an alkylol ammonium salt solution of a multifunctional polymer.

The antioxidant is added to delay the yellowing of the polyurethane resin by ultraviolet rays, and ultimately to prevent or delay color discoloration of the ink. The antioxidant can be suitably used in the present invention as long as it is commonly added to the polyurethane resin, but is not limited thereto, but tri-(2,4-di-tert-butylphenyl)phosphite (tri-(2) ,4-di-tert-butylphenyl)phosphite).

The adhesion reinforcing agent is for improving the adhesion of the ink depending on the film material, and a urea aldehyde resin or a rosin-modified maleic resin may be preferably used.

The film reinforcing agent provides activity to the ink film to prevent scratching of the film, and polyethylene wax may be preferably used.

The antistatic agent serves to auxiliary prevent electrostatic disturbance during printing by lowering the electrical resistance of the ink.

The additive may further contain a trace amount of an antifoaming agent, a surfactant, a heat resistance reinforcing agent and a transferability reinforcing agent.

The antifoaming agent removes the foaming phenomenon that occurs frequently due to the surfactant and the acid value, and the surfactant acts to wet and disperse the pigment in the ink and lower the foaming and surface tension.

When the content of the additive is outside the set range, anti-blocking properties, dispersibility, anti-oxidation, anti-static, scratch-resistance and slip-inhibiting properties may not be sufficient, and adhesion performance and mechanical properties may be deteriorated.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples. However, these examples are intended to illustrate the present invention with specific examples, and are not intended to limit the present invention thereby.

Example 1: Preparation of polyurethane urea prepolymer

45.25 Kg of polyester diol (Piothane 67-3000 HAI), 2.08 Kg of dimethylolpropionic acid DMPA and 2.35 Kg of 1,4-butanediol were mixed with 6.50 Kg of isophorone diisocyanate (IPDI) and 6.50 Kg of hexamethylene diisocyanate (HDI) in the presence of 4.24 Kg of acetone. ) was reacted with 9.53 kg at 70° C. for 2 hours and 30 minutes to prepare a polyurethane urea prepolymer.

Examples 2 to 6 and Comparative Example 1: Preparation of polyurethane resin dispersion

A polyurethane dispersion containing diisocyanate was prepared using the composition (based on weight ratio) shown in Table 1 below.

Specifically, low molecular weight polyol, modified silicone diol, dimethylolpropionic acid (DMPA) and cosolvent (n-ethyl-2-pyrrolidone, NEP) were put in a reactor equipped with an impeller, and DMPA was stirred at 70° C. for 20 minutes. completely dissolved.

Then, while maintaining the temperature of the reactor at 60 ℃, diisocyanate and dibutyltin dilaurate (DBTL) catalyst were simultaneously added and reacted for 3 hours to synthesize a polyurethane prepolymer.

After the polyurethane urea prepolymer of Example 1 was added to the reaction mixture, triethylamine (TEA, Triethylamine) as a neutralizing agent was added to neutralize the prepolymer at a temperature of 75 to 80° C. for 20 to 30 minutes, followed by constant stirring with strong stirring. Distilled water was added at a rate to prepare an aqueous ionic prepolymer product.

After cooling the aqueous ionic prepolymer to 10 ℃, ethylenediamine (EDA), a chain extender, and distilled water in which amines are dissolved are added at a constant rate to induce branch extension reaction of the prepolymer in the dispersed particles. A polyurethane resin dispersion was prepared.

Ingredients/content Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 low molecular weight polyols (1)
(weight average molecular weight 2,000) 3 3 4 3 5 10 Modified silicone diol (FMDA11) 10 5 5 20 5 - Dimethylolpropionic acid (DMPA) 2 One 2 One One 2 2,4-toluene diisocyanate 5 7 10 6 5 5 HDI - - 5 - 5 - IPDI 5 4 - 2 5 - H ₁₂ MDI - 3 5 3 - 15 Polyurethane Urea Prepolymer 2 One One One One - N-methyl-2-pyrrolidone - - - 0.5 - - NEP 1.2 0.5 0.2 0.5 0.9 One Catalyst (DBTL) 0.6 0.5 0.2 0.5 0.1 One Neutralizer (TEA) 1.2 2 0.6 0.5 One One Amines (IPDA) 5 3 2 2 2 One water 65 70 65 60 69 64 Sum 100 100 100 100 100 100

In the subsequent test, the polyurethane resin dispersion of Example 4 was selected and performed as a representative one.

Examples 7 to 11 and Comparative Example 2: Preparation of aqueous flexo ink

An aqueous flexographic ink was prepared by mixing the pigment shown in Table 2, the anionic polyurethane resin dispersion according to Example 4, water, and the like (based on weight ratio).

Ingredients/content Example 7 Example 8 Example 9 Example 10 Example 11 Comparative Example 2 pigment 18 30 19 18 40 15 Anionic polyurethane resin dispersion (Example 4) 50 36 30 25 25 20 solvent (water) 28.1 26 40.9 50.5 27 59 anti-blocking agent 0.5 0.4 One 0.1 One One dispersant One 1.5 3 2 2 One antioxidant 0.4 2 0.1 1.4 One One Adhesive reinforcing agent One 3 5 2 2 One film reinforcement 0.3 One 0.1 0.5 One One antistatic agent 0.7 0.1 0.9 0.5 One One Sum 100 100 100 100 100 100

Test Example 1: Measurement result of whiteness of water-based flexo ink printed matter

After printing on a film using the aqueous flexo ink according to Examples 7 to 11, the whiteness was compared and evaluated with that of Comparative Example 2. Two types of printing film are used, OPP and PET FILM, and surface tension is OPP 38 dyne/cm and PET 52 dyne/cm. The printing conditions are shown in Table 3.

division information
print
(Flexographic) material composition Printed film (OPP, PET) Working speed (m/min) 180 Drying temperature (℃) Dry primary (BCD): 65, dry secondary (Dry tunnel): 85 Equipment name Windmiller Flexo Printing Machine (MIRAFLEX M10)

Whiteness was measured with a color difference meter L value (Lightness) (color difference meter: x-rite eXact), and the measurement results are shown in Table 4 below.

division Example 7 Example 8 Example 9 Example 10 Example 11 Comparative Example 2 whiteness OPP 95.2 95.3 95.2 95.4 95.2 94.0 PET 94.8 94.7 94.9 95.0 94.9 93.5

As can be seen from the results of Table 4, it can be seen that the product printed with ink according to the embodiment of the present invention exhibited higher whiteness than that of the comparative example.

Test Example 2: Evaluation result of scratch resistance of water-based flexographic print

Similarly, after printing the aqueous flexo ink according to an embodiment of the present invention on a film, the scratch resistance was compared with that of Comparative Example 2, and the results are shown in Table 5. The scratch resistance evaluation method was measured with an electric pencil hardness tester H (hardness instrument: Qmesis QM450A), and the scratch resistance evaluation criteria were classified into [1] good ~ [5] poor.

division Example 7 Example 8 Example 9 Example 10 Example 11 Comparative Example 2 scratch resistance OPP ink [2] [One] [One] [2] [2] [4] PET ink [2] [2] [One] [2] [2] [4]

As can be seen from the results in Table 5, it can be seen that the product printed with the ink of the present invention has superior scratch resistance compared to that of the comparative example.

Test Example 3: Measurement result of adhesive strength of water-based flexo ink

The adhesive strength between the film on which the water-based flexo ink according to an embodiment of the present invention is printed and the adhesive used for lamination of food packaging materials was compared and evaluated with the film on which the comparative ink was printed. Table 6 shows the processing information for solvent-free adhesive paper (NSDL) applied with water-based flexo ink. Two types of printing film are used: OPP and PET film, and surface tension is OPP 38 dyne/cm, PET 52 dyne/cm, and VM-CPP 38 dyne/cm.

division information
Non-solvent Dry Lamination (NSDL) material composition Printing film/water-based ink/adhesive/VM-CPP Working speed (m/min) 300 adhesive grade Toyo morton EA-N6000/EA-N5500 Adhesive application amount 2.2 g/m2 Equipment name Shinhan Machinery Non-Solvent Machine (S.H-NSD1400)

The ink adhesion strength test results are shown in Table 7 below.

division Example 7 Example 8 Example 9 Example 10 Example 11 Comparative Example 2 Adhesive strength
(gf/15mm) Printed film/
water-based ink OPP >117 >118 >124 >120 >118 >91 PET >125 >126 >130 >126 >126 >94 Water-based ink/
glue OPP 117 118 124 120 118 91 PET 125 12 130 126 126 94

As can be seen from the results of Table 7, it can be seen that the aqueous flexo ink of the present invention has superior adhesive strength compared to that of the comparative example.

Test Example 4: Measurement result of seal strength of water-based flexo ink applied products

The effect of the water-based flexo ink on the seal strength was compared and evaluated by applying the water-based flexo ink of the present invention to form a food packaging material and then thermally bonding the sealant film, VM-CPP. The product composition was ①OPP: OPP25/water-based ink/adhesive/VM-CPP20 ② PET: PET12/water-based ink/adhesive/VM-CPP20, and sealing conditions were performed at a temperature of 130°C, a pressure of 3kgf/cm2, and a time of 0.5sec. The test results are shown in Table 8 below.

division Example 7 Example 8 Example 9 Example 10 Example 11 Comparative Example 2 Seal strength
(gf/15mm) ① OPP configuration 919 918 923 926 921 773 ② PET composition 952 950 956 957 950 807

As can be seen from the results of Table 8, it can be seen that the packaging material of the present invention exhibited a sealing strength that was 15% or more higher than that of the comparative example.

Test Example 5: Water-based flexo ink adhesive strength measurement result

The adhesive strength between the aqueous flexo ink of the present invention and LDPE used for lamination of a printing film and a food packaging material was compared and evaluated with that of Comparative Example 2. Information on water-based flexo ink application extrusion coating and lamination (EC) processing is summarized in Table 9. As before, two types of printing film were used: OPP and PET film, and surface tension was OPP 38 dyne/cm, PET 52 dyne/cm, and VM-CPP 38 dyne/cm.

division information

EC (Extruder Coating & Lamination) material composition Printing film/water-based ink/LDPE/VM-CPP Working speed (m/min) 120 Dies temperature (℃) 320 LDPE grade LG Chem LB7500F LDPE thickness 15 μm Equipment name Shinhan Machinery Coextrusion Tandem Machine (S.H-TEL1400-CO)

The test results are shown in Table 10 below.

division Example 7 Example 8 Example 9 Example 10 Example 11 Comparative Example 2 Adhesive strength
(gf/15mm) Printed film/
water-based ink OPP 85 85 86 86 85 18 PET 95 96 96 93 95 28 Water-based ink/
LDPE OPP 62 59 58 59 57 30 PET 70 68 72 69 68 43

As can be seen from the results of Table 10, it can be seen that the aqueous flexo ink of the present invention has superior adhesive strength compared to that of the comparative example.

Test Example 6: Measurement result of seal strength of water-based flexo ink applied products

After forming a food packaging material by applying the water-based flexo ink of the present invention, VM-CPP, a sealant film, was heat-bonded to compare and evaluate the effect of the water-based flexo ink on the seal strength. Product composition was ①OPP: OPP25/water-based ink/LDPE15 / VM-CPP20, ②PET: PET12/water-based ink/LDPE15/VM-CPP20. Seal conditions were a temperature of 135°C, a pressure of 3 kgf/cm 2 , and a time of 0.5 sec. The results are shown in Table 11 below.

division Example 7 Example 8 Example 9 Example 10 Example 11 Comparative Example 2 Seal strength
(gf/15mm) ① OPP configuration 856 858 857 858 859 748 ② PET composition 892 895 893 896 892 765

As can be seen from the results of Table 11, it can be seen that the packaging material of the present invention exhibited higher sealing strength than that of the comparative example.

As described above, the water-based flexo ink of the present invention has improved whiteness, so that the color development of the printing design is excellent and the printing color can be vividly realized. In addition, the water-based flexographic ink of the present invention has excellent scratch resistance, so that mechanical stability can be secured during printing and processing operations. As described above, the water-based flexo ink of the present invention has excellent ink adhesion with the printing film and interlayer adhesion with adhesives or LDPE, so that the seal strength of food packaging materials is improved. It is a helpful eco-friendly ink.

In addition, the water-based flexographic printing of the present invention is an absolutely necessary printing method that can improve air pollution by not using the organic solvent used in the currently general gravure printing method.

As such, although the present invention has been described with reference to the drawings and the specification for preferred embodiments of the present invention, it is apparent that various modifications and equivalent implementations are possible by those skilled in the art.

Claims (6)

Pigment, anionic polyurethane resin dispersion, containing water and additives as a diluting solvent, the anionic polyurethane resin dispersion is aromatic diisocyanate 5-10 wt%, aliphatic diisocyanate 5-10 wt%, modified silicone diol 5-20 wt%, low molecular weight polyol 3-5 wt%, polyurethane urea prepolymer 1-2 wt%, other additives 1-3 wt%, dimethylolpropionic acid 1-2 wt%, amines 2-5 wt% and water 60 It is prepared from a composition containing ~70% by weight, wherein the low molecular weight polyol is represented by the following formula (1) and a weight average molecular weight of 1,000 ~ 2,000, characterized in that the aqueous flexographic ink composition for printing.

(Wherein, n is an integer of 8 to 20.) The method according to claim 1,
An aqueous flexographic printing ink composition comprising 18 to 40% by weight of a pigment, 25 to 50% by weight of an anionic polyurethane resin dispersion, 26 to 50.5% by weight of water, and 3.4 to 10.1% by weight of an additive. The method according to claim 1,
The additive comprises 0.1 to 1% by weight of an antiblocking agent, 1 to 3% by weight of a dispersant, 0.1 to 2% by weight of an antioxidant, 1 to 5% by weight of an adhesion reinforcing agent, 0.1 to 1% by weight of a film reinforcing agent, and 0.1 to 1% by weight of an antistatic agent Aqueous flexographic ink composition for printing, characterized in that it comprises. The method according to claim 1,
wherein the aromatic diisocyanate is 2,4- or 2,6-toluene diisocyanate;
The aliphatic diisocyanate is hexamethylene diisocyanate, isophorone diisocyanate or bis(4-isocyanatocyclohexyl)methane;
The modified silicone diol is a monodicarbinol terminated polydimethylsiloxane polyol,
The amines are one or two selected from the group consisting of hydrazine hydrate, ethylenediamine, isophoronediamine, and diethylenetriamine;
The other additives are n-ethyl-2-pyrrolidone cosolvent, N-methyl-2-pyrrolidone dissolution promoter, dibutyltin dilaurate, tetrabutyl titanate, dibutyltin dilaurylate, Aqueous flexographic printing ink composition, characterized in that it is an organometallic catalyst selected from a bismuth compound or a zinc compound, and a neutralizing agent that is triethylamine or dimethylethanolamine. The method according to claim 1,
The polyurethane urea prepolymer is an aqueous flexographic printing ink composition, characterized in that it is prepared by reacting a polyisocyanate component containing a diisocyanate, a carboxyl group-containing monomer and a polyol component in the presence of a water-soluble volatile organic solvent at a temperature of room temperature to 100 °C. The method according to claim 1,
The aromatic diisocyanate and the aliphatic diisocyanate are aqueous flexographic ink composition, characterized in that it is included in a weight ratio of 1: 0.9 to 1.1.

Images