KR101779572B1 - Ink Composition for Gravure Printing Comprising Alcohol-Soluble Urethane Resin - Google Patents

Abstract

The present invention relates to an ink composition for gravure printing comprising: (A) 20 to 40 wt% of an alcohol-soluble urethane resin; (B) 10 to 30 wt% of a pigment; (C) 0.1 to 16 wt% of an additive; and (D) a remainder consisting of ethanol. The ink composition does not contain any organic solvents classified as hazardous chemicals under the Chemical Substance Control Act, thereby being eco-friendly.

Description

[0002] Ink Composition for Gravure Printing Comprising Alcohol-Soluble Urethane Resin [0003]

The present invention relates to an ink composition for gravure printing. More particularly, the present invention relates to an environmentally friendly gravure printing ink composition containing no organic solvent classified as toxic according to the Chemical Substance Control Law.

Gravure printing refers to engraved photographic plate making process in which the image to be printed is scraped onto the surface of the printing plate. It is a type that scraped and prints extra ink with a doctor blade by applying ink on the corrugated plate which is corroded by corrosion. . The ink used here is referred to as a gravure ink.

Generally, gravure printing is performed by using an organic solvent such as toluene, methyl ethyl ketone (MEK), ethylacetate (EA), xylene, and ethyl cellosolve (EC) Inks are used. All of these organic solvents are volatile organic compounds (VOCs), and are known to have harmful effects on the human body and the environment as well as odor.

Specifically, such an organic solvent is released to the atmosphere in the drying process of the ink to become an air pollutant source, is directly exposed to an operator and is harmful to the human body, and has a risk of fire in printing operation. In particular, when such organic solvent remains in the printed matter, hygienic printed matter can not be obtained, and organic solvents having low boiling points are evaporated during the printing process, thereby changing the viscosity of the ink, thereby deteriorating printability.

In addition, according to the revised Hazardous Chemical Substances Control Act revised in 2015, standards for the installation of handling facilities and the wearing of workers' protective gear have been strengthened, and the restrictions on the storage, management and handling of such organic solvents will be limited.

As an alternative, the use of aqueous gravure ink in gravure printing has been considered, but it has been disadvantageous in that it can not be used in general gravure printing equipment because it is not universally used for various reasons such as printing drying problems and productivity deterioration.

In the conventional alcoholic ink composition, methanol is used as a solvent. Since the vinyl resin (for example, polyvinyl chloride) used together is not dissolved, the ink is not uniformly printed and methanol is hardly volatile, It fell. In addition, methanol is a toxic substance and has the same problems as the above-mentioned organic solvents.

DISCLOSURE OF THE INVENTION The present inventors have found that such a problem can be solved when a chemical substance having good compatibility and solubility with ethanol as the main material, for example, an alcohol soluble urethane resin, is used, thereby completing the present invention. The present invention does not contain toxic substances in the constituent components and is environment-friendly to use ethanol as a solvent and can be free from the chemical management method.

It is an object of the present invention to provide an ink composition for gravure printing that is environmentally friendly because it contains no toxic substances.

Another object of the present invention is to provide an ink composition for gravure printing which has a small amount of residual solvent and low odor.

Another object of the present invention is to provide an ink composition for gravure printing which is excellent in printing workability and color expressing power.

Another object of the present invention is to provide an ink composition for gravure printing which is applicable to various printing films such as OPP, PET, nylon, and aluminum foil.

The above and other objects of the present invention can be achieved by the present invention described below.

According to an aspect of the present invention,

(A) 20 to 40% by weight of an alcohol-soluble urethane resin;

(B) 10 to 30% by weight of a pigment;

(C) 0.1 to 16% by weight of an additive; And

(D) the remainder of ethanol.

The alcohol-soluble urethane resin (A) is synthesized by reacting a polyether polyol with an aliphatic isocyanate to prepare a prepolymer and then polymerizing with a diamine.

Wherein the polyether polyol is a polytetramethylene ether glycol, polyethylene glycol, polypropylene glycol or a mixture thereof, and the aliphatic isocyanate is hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-methylenedicyclohexyl diisocyanate, , And the diamine is preferably isophoronediamine, ethylenediamine or a mixture thereof

The alcohol-soluble urethane resin (A) may be represented by the following formula (1)

≪ Formula 1 >

In the above formula (1), R and R 'are each independently a C ₁ -C ₆ alkylene group and n is an integer of 5 to 170.

The alcohol-soluble urethane resin (A) preferably has a viscosity of 8,000 to 11,000 cps at 25 ° C, a solid content of 46 to 50%, and a molecular weight (Mw) of 30,000 to 35,000.

 The present invention does not include an organic solvent composed of toluene, methyl ethyl ketone, ethyl acetate, or a mixture thereof, and can be used by diluting with ethanol alone.

Preferably, the additive is 0.1 to 1% by weight of a dispersing agent, 0.1 to 1% by weight of an antifoaming agent, 0.1 to 1% by weight of an adhesive reinforcing agent, 0.5 to 3% by weight of a wax, 5 to 10% by weight of glycol or a mixture thereof.

The present invention has the effect of providing an ink composition for gravure printing that is environmentally friendly, has a small residual solvent amount and odor, and is usable in general use with excellent printing workability and color expressing power.

FIG. 1 is a 500-fold magnified image of the printing result of 23 sulfur ink prepared with the compositions of Example 1 and Comparative Example 1. FIG.
Fig. 2 is a photograph showing a 500-fold magnification of the printing result of the red ink prepared in Example 2 and Comparative Example 2. Fig.
Fig. 3 is a photograph showing a 500-fold magnification of the printing result of 39 blue inks prepared with the compositions of Example 3 and Comparative Example 3. Fig.
Fig. 4 is a photograph showing a 500-fold magnification of the printing result of the black ink prepared in Example 4 and Comparative Example 4. Fig.
Fig. 5 is a photograph showing a comparison of the color expressive power of the face portions of a printed design printed using the inks of Examples 1 to 4 and the inks of Comparative Examples 1 to 4; Fig.
Fig. 6 is a photograph comparing the color expressive power of the ink of Examples 1 to 4 and the attention-paid portion of the printed design printed using the inks of Comparative Examples 1 to 4. Fig.

The present invention uses ethanol as an organic solvent to provide an environment-friendly, non-toxic organic solvent which is different from conventional ink compositions and has less residual solvent amount and odor than conventional ink, To a gravure printing ink composition.

The ink composition for gravure printing according to the present invention comprises an alcohol-soluble urethane resin (A), a pigment (B), an additive (C) and an organic solvent (D) as a binder resin.

The gravure printing ink composition of the present invention comprises 20 to 40% by weight of an alcohol-soluble urethane resin (A), 10 to 30% by weight of a pigment (B), 0.1 to 16% by weight of an additive (C) .

The present invention includes an alcohol-soluble urethane resin (A) to dilute ethanol alone, which is not a toxic substance, to prepare an ink composition for gravure printing having appropriate fluidity and viscosity.

The alcohol-soluble urethane resin (A) serves to color the ink composition on the substrate, enhances the adhesion between the ink and the substrate, and improves the quality of the gravure printing. Examples of the substrate include OPP, PET, nylon, and aluminum foil. Therefore, the ink composition of the present invention is also applicable to Snack, Boil, Hi-Retort.

The alcohol-soluble urethane resin (A) can be synthesized by reacting a polyether polyol with an aliphatic isocyanate to prepare a prepolymer, and then polymerizing with a diamine. The polyether polyol may have a molecular weight of 1,000 to 4,000.

The polyether polyol is preferably selected from the group consisting of Polytetramethylene Ether Glycol (PTG), Polyethylene Glycol (PEG), Polypropylene Glycol (PPG), and mixtures thereof.

The aliphatic isocyanate may be selected from the group consisting of hexamethylene diisocyanate (HDI), isophoronediisocyanate (IPDI), 4,4'-methylenedicyclohexyl diisocyanate (H12MDI) .

Also, the diamine is preferably isophorone diamine (IPDA), ethylene diamine or a mixture thereof.

The alcohol-soluble urethane resin (A) is a resin suitable for use together with ethanol as a solvent, and is represented by the following formula (1)

≪ Formula 1 >

In the above formula (1), R and R 'are each independently a C ₁ -C ₆ alkylene group and n is an integer of 5 to 170. Preferably, n is an integer from 50 to 170, and more preferably n is an integer from 70 to 163.

The specific gravity of the alcohol-soluble urethane resin (A) is 0.85 to 0.95, the solid content is 46 to 50%, and the viscosity is preferably 8,000 to 11,000 cps at 25 占 폚. The molecular weight (Mw) of the alcohol-soluble urethane resin (A) is preferably 30,000 to 35,000.

In addition to the alcohol-soluble urethane resin (A), a vinyl resin may be added in order to improve the adhesion between the ink and the substrate and the quality of the gravure printing. The vinyl resin to be added is preferably polyvinyl butyral (PVB) which is soluble in alcohols in consideration of compatibility with ethanol and solubility.

The polyvinyl butyral (PVB) is preferably contained in an amount of 1 to 4% by weight based on 100% by weight of the gravure printing ink composition.

The alcohol-soluble urethane resin (A) may be contained in an amount of 20 to 40% by weight, and preferably 25 to 35% by weight. When the alcohol-soluble urethane resin (A) is less than 20% by weight, the boiling adhesive strength is lowered. When the alcohol-soluble urethane resin (A) is more than 40% by weight, ink viscosity, printing compatibility and boiling adhesion may be lowered.

The boiling adhesive force is preferably such that when the contents are sterilized at 125 ° C to 135 ° C for 30 minutes, the packaging material is prevented from being damaged due to breakage and separation of the printed ink from the printing substrate (Film) Film refers to the adhesion of the ink to the ink.

The pigment (B) is not particularly limited as long as it can be used for gravure printing, and any pigment can be used. For example, pigment pigments, phosphorescent pigments, photochromic powders, thermochromic powders and the like can be used. Such a pigment (B) is preferably contained in an amount of 10 to 30% by weight in the ink composition for gravure printing. If the content is less than the above range, the color expressing ability is deteriorated. If the content exceeds the above range, the printing properties and storage stability due to the viscosity increase may be deteriorated.

The gravure printing ink composition may comprise from 0.1 to 16% by weight of an additive. Examples of the additives include a dispersant, a defoaming agent, an adhesive reinforcing agent, a wax agent, and a glycol. These additives may be used singly or in combination. Preferably, 0.1 to 1% by weight of a dispersant, 0.1 to 1% by weight of a defoamer, 0.1 to 1% by weight of an adhesion promoter, 0.5 to 3% by weight of a wax, 5 to 10% by weight of a glycol or a mixture thereof may be used as an additive .

Here, the dispersing agent disperses the pigment stably at a high concentration, and the defoaming agent serves to suppress and remove bubbles of ink at the time of printing. The wax agent improves the slip property and scratch resistance of the printing surface. Glycol serves to improve the dispersibility of the pigment and the stability of the ink, and helps to improve the transferability of the printing cylinder and reduce the plate thickness.

As described above, generally, gravure printing is performed by using an ink containing an organic solvent such as toluene, methyl ethyl ketone (MEK), ethyl acetate (EA), xylene, ethyl cellosolve (EC) I am using it. However, all of these organic solvents are volatile organic compounds (VOCs), which have harmful effects on the human body and the environment as well as odor. However, the present invention is environmentally friendly using ethanol as a solvent.

The physical properties of ethanol and other solvents used as the solvent of the present invention are shown in Table 1 below.

As shown in Table 1, ethanol is not a toxic substance, and the permissible concentration in the workplace is 1,000 ppm, which is higher than other solvents. However, other organic solvents are toxic substances, and the permissible concentrations in the workplace are relatively low compared to ethanol.

The present invention includes an alcohol-soluble urethane resin (A) so that ethanol (D), which is not a toxic substance, can be diluted alone to have appropriate fluidity and viscosity.

At this time, ethanol (D) is used as the remainder so that the ink composition satisfies 100% by weight of the total amount. Preferably, ethanol (D) may be used in an amount of 20% by weight to 50% by weight. However, due to the lack of drying ability in the old printing equipments, it may cause defective operation such as the detachment of the guide roll during printing, block printing of the printed matter, detection of excessive solvent, etc. In order to control the volatilization rate, n-PAc, C-Hexane or the like may further be used.

The present invention is preferably a two-component ink composition for gravure printing.

Hereinafter, the following examples will be presented to facilitate understanding of the present invention. However, the following examples are provided only for the purpose of easier understanding of the present invention, and the present invention is not limited by the examples.

Example

≪ Example 1 >

(D) containing 25% by weight of an alcohol-soluble urethane resin (A), 11% by weight of a pigment (B), 14% by weight of an additive (C) comprising a dispersant, an antifoaming agent, A gravure printing ink composition was prepared. The color of the pigment was 23 sulfur.

≪ Example 2 >

The ink composition for gravure printing was prepared in the same manner as in Example 1, except that the color of the pigment was red.

≪ Example 3 >

The ink composition for gravure printing was prepared in the same manner as in Example 1, except that the color of the pigment was 39 g.

<Example 4>

The ink composition for gravure printing was prepared in the same manner as in Example 1, except that the color of the pigment was black.

&Lt; Example 5 >

The prints were printed using the ink compositions of Examples 1, 2, 3 and 4 (Pigment Ink).

&Lt; Example 6 >

The prints were printed using the ink compositions of Examples 1, 2, 3 and 4 (Pigment Ink).

&Lt; Comparative Example 1 &

Except that a solvent type urethane resin (A-9003E of Songwon Industrial Co., Ltd.) was used in place of the alcohol-soluble urethane resin as the binder resin, and MEK and EA were used in place of ethanol as the organic solvent, gravure ink A composition was prepared. The color of the pigment was 23 sulfur.

25% by weight of a solvent type urethane resin, 11% by weight of a pigment, 14% by weight of an additive and 25% by weight of MEK and 25% by weight of EA.

&Lt; Comparative Example 2 &

The ink composition for gravure printing was prepared in the same manner as in Comparative Example 1, except that the color of the pigment was red.

&Lt; Comparative Example 3 &

The ink composition for gravure printing was prepared in the same manner as in Comparative Example 1 except that the color of the pigment was 39 g.

&Lt; Comparative Example 4 &

The ink composition for gravure printing was prepared in the same manner as in Comparative Example 1, except that the color of the pigment was black.

&Lt; Comparative Example 5 &

The prints were printed using the ink compositions of Comparative Examples 1, 2, 3 and 4 (dye Ink).

&Lt; Comparative Example 6 >

The prints were printed using the ink compositions of Comparative Examples 1, 2, 3 and 4 (dye Ink).

&Lt; Comparative Example 7 &

A gravure printing ink composition comprising 18% by weight of an alcohol soluble urethane resin, 11% by weight of a pigment, 14% by weight of an additive including a dispersant, an antifoaming agent, an adhesion promoter, a wax agent and a glycol, and 57% by weight of ethanol was prepared.

&Lt; Comparative Example 8 >

A gravure printing ink composition comprising 42% by weight of an alcohol-soluble urethane resin, 11% by weight of a pigment, 14% by weight of an additive including a dispersant, an antifoaming agent, an adhesive reinforcing agent, a wax agent and a glycol, and 33% by weight of ethanol was prepared.

<Printability verification>

In order to confirm the effects of the present invention, the printing properties of Examples 1 to 6 and Comparative Examples 1 to 8 were verified. The working conditions of printability verification are as follows.

1. Copper plate: Copper plate for CMS - HERIO plate

Film 2: PET Film (700 mm x 12 mm x 1,800 m)

3. Printing Dry Unit Temperature: Color - 60 ℃, White - 90 ℃

4. Ink Dilution: Maintains the dilution ratio of the existing printing method - 30% colored, 100% white.

5. Printing Speed: 150 m / min

6. Holy Grain Machine Gravure Printing Machine - 9 degrees

The physical properties of Example 1 and Comparative Examples 7 and 8 according to the content of the alcohol-soluble urethane resin (A) are shown in Table 2 below.

Example 1 Comparative Example 7 Comparative Example 8 Ink color expressiveness Good Good Good Ink fluidity Good Good Bad Print suitability Good Good Bad Boiling adhesion Good Bad Bad

The method of measuring the physical properties is as follows.

Ink Color Expression: Color comparison with existing print samples (using visual and CMS instruments)

Ink fluidity: Viscosity measurement using a viscometer (CUP type, Brookfield Viscometer)

Printing suitability: Color and printing suitability in printing process (Adhesion, Blocking) Check

Boiling: Ink has Tacky and bad adhesion to back side of substrate film

Adhesive strength: Measurement of bonding strength between film and ink, which is a printing substrate, using -3M tape

As shown in Table 2, when the content of the alcohol-soluble urethane resin (A) was within the claimed range, all measured physical properties were good. However, when the content exceeded the claimed range, the measured physical properties were deteriorated.

Claims (9)

(A) 20 to 40% by weight of an alcohol-soluble urethane resin;
(B) 10 to 30% by weight of a pigment;
(C) 0.1 to 16% by weight of an additive; And
(D) a residual solvent of ethanol,
The alcohol-soluble urethane resin (A) is prepared by reacting a polyether polyol with an aliphatic isocyanate to prepare a prepolymer, and then synthesizing the prepolymer by polymerization with a diamine. delete The polyurethane foam of claim 1, wherein the polyether polyol is polytetramethylene ether glycol, polyethylene glycol, polypropylene glycol or a mixture thereof, and the aliphatic isocyanate is hexamethylene diisocyanate, isophorone diisocyanate, 4,4'- Wherein the diamine is isophoronediamine, ethylenediamine, or a mixture thereof, wherein the diamine is isophoronediamine, ethylenediamine, or a mixture thereof. The two-component ink composition for gravure printing according to claim 1, wherein the alcohol-soluble urethane resin (A) is represented by the following formula (1)
&Lt; Formula 1 >

In the above formula (1), R and R 'are each independently a C ₁ -C ₆ alkylene group and n is an integer of 5 to 170. The two-part ink composition for gravure printing according to claim 1, wherein the alcohol-soluble urethane resin (A) has a viscosity of 8,000 to 11,000 cps at 25 ° C. The two-part ink composition for gravure printing according to claim 1, wherein the solid content of the alcohol-soluble urethane resin (A) is 46 to 50%. The two-part ink composition for gravure printing according to claim 1, wherein the alcohol-soluble urethane resin (A) has a molecular weight (Mw) of 30,000 to 35,000. delete 8. The composition of any one of claims 1 to 7, wherein the additive comprises 0.1 to 1% by weight of a dispersant, 0.1 to 1% by weight of an antifoam, 0.1 to 1% by weight of an adhesion promoter, 0.5 to 3% , 5 to 10% by weight of glycol, or a mixture thereof.

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