A transparent yellow ink composition for CPP aluminum-plated film printing and a preparation method thereof

Abstract

The present application belongs to the technical field of packaging printing ink, and specifically provides a transparent yellow ink composition for CPP aluminum-coated film printing and a preparation method thereof, which comprises the following components in mass percentage: acrylic resin A, 2-8% acrylic resin B, 2-6% transparent yellow pigment, 1-5% orange pigment, 25-45% solvent A, 25-45% solvent B, 0.5-5% adhesion promoter and 0.05-1% additive, wherein the sum of the mass percentages of the components is 100%. The present application uses specific acrylic resin A and acrylic resin B as the main resin system by compounding, and adds chlorinated polypropylene adhesion promoter, so that the adhesion of the transparent yellow ink to the CPP aluminum-coated film reaches 5B grade in the crosshatch method, and the residual area in the tape peeling test reaches 100%, completely solving the problems of powder falling and peeling off after existing transparent yellow ink aluminum coating.

Description

Technical Field

[0001] This invention belongs to the field of packaging printing ink technology, specifically relating to a transparent yellow ink composition for CPP metallized film printing and its preparation method. Background Technology

[0002] CPP film (cast polypropylene film) is widely used in the packaging of food, daily chemical, and other products due to its excellent heat-sealing properties, transparency, and mechanical strength. To enhance the aesthetics and grade of the packaging, a process of metallizing the CPP film after printing is often used to give the packaging a metallic luster.

[0003] Currently, existing transparent yellow ink products used for CPP film printing mainly adopt an acrylic resin system, using transparent yellow powder as pigment, combined with solvents such as n-propyl ethyl ester and wax powder and other additives. Its typical preparation process is as follows: after mixing and dispersing the resin, solvent and additives, the transparent yellow pigment is added, and then the mixture is ground to a fineness of ≤10μm using a dispersion device.

[0004] However, existing transparent yellow ink products have several problems in the application of CPP film printing followed by metallization. First, poor adhesion, leading to powdering and peeling after metallization. Second, insufficient gloss, with a dull metallic luster that fails to meet the aesthetic requirements of high-end packaging. Third, poor metallization adaptability, resulting in pitting, darkening, and decreased adhesion after metallization, with issues such as color fading, pitting, poor adhesion, partial peeling, and a darker color. Fourth, poor printability, poor leveling, and re-sticking. Fifth, poor storage stability, exhibiting thickening after prolonged storage. Therefore, there is a need to develop a transparent yellow ink composition with excellent adhesion, high gloss, good metallization adaptability, and printability for CPP film printing followed by metallization. Summary of the Invention

[0005] The present invention aims to provide a transparent yellow ink composition for printing on CPP aluminized film and its preparation method, in order to solve the technical problems of insufficient adhesion of existing transparent yellow ink to CPP aluminized film, decreased gloss and weak metallic feel after aluminization, color fading and discoloration after aluminization, poor printability and poor storage stability.

[0006] Specifically, the present invention provides the following technical solution: A transparent yellow ink composition for printing on CPP metallized films comprises the following components by weight percentage: Acrylic resin A 10%–30%; Acrylic resin B 2%~12%; Transparent yellow pigment 2%–6%; Orange pigment 1%–5%; Solvent A 25%–45%; Solvent B 25%–45%; Adhesion promoter 0.5%–5%; Additives 0.05%–1%; The sum of the mass percentages of the components is 100%.

[0007] Preferably, the transparent yellow ink composition comprises the following components in weight percentage: Acrylic resin A 14%–18%; Acrylic resin B 3%–5%; 3%–5% transparent yellow pigment; Orange pigment 2%–4%; Solvent A 30%–40%; Solvent B 30%–40%; Adhesion promoter 1%–3%; Additives: 0.1%–0.5%.

[0008] Most preferably, the transparent yellow ink composition comprises the following components in weight percentage: Acrylic resin A 16.3%; Acrylic resin B 4.2%; Transparent yellow pigment 4.1%; Orange pigment 2.9%; Solvent A 35.3%; Solvent B 35%; Adhesion promoter 2%; Additives 0.2%.

[0009] In the transparent yellow ink composition of the present invention, the acid values ​​of both acrylic resin A and acrylic resin B are ≤1 mg KOH / g, and the hydroxyl values ​​are ≤5 mg KOH / g (preferably substantially free of hydroxyl groups). Low acid values ​​help improve the heat resistance of the ink, and extremely low hydroxyl values ​​prevent unnecessary cross-linking side reactions at the interface between the resin and the aluminum plating layer at high temperatures, thereby ensuring the stability of adhesion after aluminum plating.

[0010] In the transparent yellow ink composition of the present invention, the particle size of the transparent yellow pigment and the orange pigment is 0.5–10 μm. Suitable pigment particle size contributes to obtaining good transparency and dispersibility.

[0011] In the transparent yellow ink composition of the present invention, solvent A is n-propyl ester and solvent B is ethyl acetate. The combined use of n-propyl ester and ethyl acetate can effectively dissolve the resin system and provide a suitable evaporation rate.

[0012] In the transparent yellow ink composition of the present invention, the adhesion promoter is a chlorinated polypropylene-based adhesion promoter. Chlorinated polypropylene-based adhesion promoters have good affinity for both polypropylene substrates and aluminum metal surfaces, and can significantly improve the adhesion between the ink and the CPP aluminized film.

[0013] In the transparent yellow ink composition of the present invention, the additive is an amide-based slip agent, which is used to impart good slip properties to the ink and improve its printability.

[0014] The present invention also provides a method for preparing the above-mentioned transparent yellow ink composition, comprising the following steps: Step S1: Mix solvent A, transparent yellow pigment and orange pigment according to the specified ratio, and stir at 20-30℃ for 20-40 minutes to obtain a mixed color paste; Step S2: Add solvent B, acrylic resin A, and acrylic resin B to the mixed color paste obtained in step S1, and stir and disperse at 800-1200 rpm for 20-40 minutes at 20-30°C. Step S3: Add adhesion promoter and additive to the product of step S2, and stir and disperse at 700-1000 rpm for 15-30 min at 20-30℃; Step S4: Grind and disperse the product from step S3 in a horizontal sand mill until the fineness is ≤10μm; Step S5: Add solvent A and / or solvent B as needed, adjust the viscosity to 25-35 seconds at 25°C and a No. 4 cup, filter the material to obtain the transparent yellow ink composition.

[0015] Preferably, the stirring time in step S1 is 30 minutes and the stirring temperature is 25°C.

[0016] Preferably, the stirring and dispersion time in step S2 is 30 min, the stirring temperature is 25℃, and the stirring speed is 1000 rpm.

[0017] Preferably, the stirring and dispersion time in step S3 is 20 min, the stirring temperature is 25℃, and the stirring speed is 850 rpm.

[0018] Compared with the prior art, the beneficial effects of the present invention are: This invention uses a specific blend of acrylic resin A and acrylic resin B as the main resin system and adds a phosphate ester adhesion promoter to achieve a 5B grade of cross-cut adhesion on CPP aluminized film, with 100% residual area in the tape peel test. This completely solves the problem of powdering and peeling off of existing transparent yellow ink after aluminization.

[0019] The metallic gloss (60°) of the transparent yellow ink of this invention reaches 199, which is significantly improved compared with the prior art. After aluminum plating, the appearance is free of pitting and dullness, with a strong metallic feel, which meets the aesthetic requirements of high-end packaging.

[0020] The transparent yellow ink of this invention, after being aluminum-plated and heat-sealed, achieves a composite peel strength of 2-2.5 N / 15 mm and a heat-sealing strength of 5 N / 15 mm, without delamination, demonstrating excellent composite performance.

[0021] The transparent yellow ink of this invention has good storage stability. After being stored at 25°C for 30 days and at 50°C for 7 days, there is no significant change in viscosity and fineness, and no sedimentation, thickening, or discoloration.

[0022] This invention provides a transparent yellow ink that does not bleed under high-temperature aluminizing conditions and is heat-resistant, solving the industry problem that ordinary inks cannot meet the requirements of aluminizing and placing it in a leading position in the printing industry. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0024] Figure 1 This is a flowchart illustrating the preparation process of the transparent yellow ink composition of the present invention.

[0025] Figure 2 This is a comparison diagram of the adhesion between Example 1 and Comparative Example 1 of the present invention.

[0026] Figure 3 This is a comparison chart of gloss levels between Example 1 and Comparative Example 1 of the present invention.

[0027] Figure 4 This is a photograph of a printed sample from Embodiment 1 of the present invention. Detailed Implementation

[0028] The present invention will be further illustrated below with specific embodiments. These embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Those skilled in the art should understand that this application can be implemented even without certain specific details. Without conflict, the technical features disclosed in the embodiments of this application can be combined arbitrarily.

[0029] In the following embodiments, acrylic resin A and acrylic resin B are both commercially available low-acid-value, low-hydroxyl-value solvent-based acrylic resins; the adhesion promoter is a chlorinated polypropylene adhesion promoter (such as Nippon Paper 390S); and the amide-based slip agent is preferably an unsaturated fatty acid amide (such as oleamide or erucamide). All of the above raw materials are commercially available in the ink industry, and this invention is not limited to specific grades.

[0030] Example 1 The formulation of the transparent yellow ink composition in this embodiment is shown in Table 1.

[0031] Preparation method: Step S1: Add n-propyl ester, transparent yellow pigment and orange pigment to a dispersion tank according to the specified ratio, and stir at 25°C for 30 minutes to obtain a mixed color paste; Step S2: Add ethyl acetate, acrylic resin A and acrylic resin B to the mixed color paste obtained in step S1, and stir and disperse at 1000 rpm for 30 min at 25°C. Step S3: Add chlorinated polypropylene adhesion promoter and amide slip agent to the product of step S2, and stir and disperse at 850 rpm for 20 min at 25°C. Step S4: Grind and disperse the product from step S3 in a horizontal sand mill until the fineness is ≤10μm; Step S5: Add n-propyl ester to adjust the viscosity to 28 seconds at 25°C and a No. 4 cup. Filter the material to obtain the transparent yellow ink composition.

[0032] Example 2 The only difference between this embodiment and Example 1 is the mass percentage of each component in the formula, as shown in Table 1. The preparation method is the same as in Example 1.

[0033] Example 3 The only difference between this embodiment and Example 1 is the mass percentage of each component in the formula, as shown in Table 1. The preparation method is the same as in Example 1.

[0034] Comparative Example 1 The difference between this comparative example and Example 1 is that a commercially available conventional acrylic resin (specifically Mitsubishi Chemical BR-106, acid value > 5 mg KOH / g, containing hydroxyl groups) is used instead of the acrylic resin A and acrylic resin B selected in this invention, and no adhesion promoter is added. The remaining components and preparation methods are the same as in Example 1.

[0035] Comparative Example 2 The difference between this comparative example and Example 1 is that the ratio of acrylic resin A to acrylic resin B exceeds the scope of this invention (the mass ratio of resin A to resin B was adjusted to more than 5:1, resulting in severe discoloration during aluminum plating). The remaining components and preparation methods are the same as in Example 1.

[0036] The formulation composition (mass percentage, %) of Examples 1-3 and Comparative Examples 1-2 is shown in Table 1.

[0037] Performance testing The transparent yellow ink products of Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests. The testing methods for each performance aspect are as follows: Fineness: Determined using a scraper fineness tester in accordance with GB / T 13217.3-2022; Viscosity: Measured at 25℃ using a #4 viscosity cup, in accordance with GB / T 13217.4-2022. Solid content: Determined after drying in a drying oven at 120℃ for 120 min, in accordance with GB / T 1725-2007; Initial drying / complete drying: determined using a scraper fineness tester according to GB / T 13217.5; Adhesion (cross-cut test): According to GB / T 9286-2021, the cross-cut test is used for determination, and the grading standard is 0B~5B; Tape peel test: After applying 3M 610 tape, peel it off at a 180° angle and observe the percentage of ink residue area. Metallic luster: measured using a 60° gloss meter, in accordance with GB / T 9754-2007; Colorimetric values ​​(L, a, b): determined using a colorimeter in accordance with GB / T 7921-2008; Opacity: Determined using the black and white grid paper method, in accordance with GB / T 1726-1979; Composite peel strength: measured with a 15mm width using a digital push-pull force gauge, in accordance with GB / T 8808-1988; Heat seal strength: Measured using a digital push-pull force gauge, in accordance with QB / T 2358-1998; Storage stability: After being stored at 25℃ for 30 days and at 50℃ for 7 days, the viscosity, fineness, sedimentation and discoloration were observed. Transfer rate: Measured after sampling on CPP film using a wire rod or sampling machine; Leveling property: visual rating, 1 to 5 (5 being the best); Plate clogging tendency: Print continuously on a gravure printing press for 30 minutes and observe the plate clogging situation; Ethanol resistance test: A cotton cloth was soaked in anhydrous ethanol and repeatedly wiped with a 500g weight. The number of wiping cycles before ink flaking was observed. Water resistance: The printed sample was immersed in deionized water for 24 hours and then removed to test the retention of adhesion. Oil resistance: Immerse the printed sample in edible oil for 24 hours and then remove it to observe the changes in appearance.

[0038] Table 2 Basic Technical Specifications of Finished Inks

[0039] Note: “—” in Table 2 indicates that this item was not tested separately.

[0040] Table 3 Adhesion Test Data

[0041] Table 4 Optical performance data

[0042] Table 5 Composite strength data (after aluminizing and laminating with CPP film)

[0043] Table 6 Storage stability data

[0044] Table 7 Printability Data

[0045] Table 8. Durability Test Data

[0046] The test results above show that the transparent yellow ink composition of Example 1 of this invention exhibits excellent performance in terms of adhesion, gloss, composite strength, storage stability, and printability. Example 2, even with the adhesion promoter reduced to 1.0%, still maintains a 5B adhesion level and a high gloss of 197, demonstrating that excellent results can be achieved within the preferred range of this invention. In contrast, Comparative Example 1 (using conventional hydroxyl-containing acrylic resin without adding an adhesion promoter) and Comparative Example 2 (resin ratio exceeding the range of this invention) both showed severe color fading and adhesion degradation after aluminum plating, indicating that this invention, through the selection of a specific resin system, the addition of an adhesion promoter, and the optimization of the component ratios, achieves significantly superior technical effects compared to existing technologies.

[0047] Although the invention has been illustrated and described with reference to specific embodiments, it will be apparent to those skilled in the art that many other variations and modifications can be made without departing from the spirit and scope of the invention. Therefore, all such variations and modifications falling within the scope of the invention are intentionally included in the appended claims.

Claims

1. A transparent yellow ink composition for printing on CPP aluminized films, characterized in that, Includes the following components by mass percentage: Acrylic resin A 10%–30%; Acrylic resin B 2%~12%; Transparent yellow pigment 2%–6%; Orange pigment 1%–5%; Solvent A 25%–45%; Solvent B 25%–45%; Adhesion promoter 0.5%–5%; Additives 0.05%–1%; The sum of the mass percentages of the components is 100%.

2. The transparent yellow ink composition for CPP aluminized film printing according to claim 1, characterized in that, Includes the following components by mass percentage: Acrylic resin A 14%–18%; Acrylic resin B 3%–5%; 3%–5% transparent yellow pigment; Orange pigment 2%–4%; Solvent A 30%–40%; Solvent B 30%–40%; Adhesion promoter 1%–3%; Additives: 0.1%–0.5%.

3. The transparent yellow ink composition for CPP aluminized film printing according to claim 1, characterized in that, Includes the following components by mass percentage: Acrylic resin A 16.3%; Acrylic resin B 4.2%; Transparent yellow pigment 4.1%; Orange pigment 2.9%; Solvent A 35.3%; Solvent B 35%; Adhesion promoter 2%; Additives 0.2%.

4. The transparent yellow ink composition for CPP aluminized film printing according to any one of claims 1 to 3, characterized in that, The acid values ​​of both acrylic resin A and acrylic resin B are ≤1 mg KOH / g, and the hydroxyl values ​​are ≤5 mg KOH / g.

5. The transparent yellow ink composition for CPP aluminized film printing according to any one of claims 1 to 3, characterized in that, The particle size of the transparent yellow pigment and the orange pigment is 0.5–10 μm.

6. The transparent yellow ink composition for CPP aluminized film printing according to any one of claims 1 to 3, characterized in that, Solvent A is n-propyl ester, and solvent B is ethyl acetate.

7. The transparent yellow ink composition for CPP aluminized film printing according to any one of claims 1 to 3, characterized in that, The adhesion promoter is a chlorinated polypropylene-based adhesion promoter.

8. The transparent yellow ink composition for CPP metallized film printing according to any one of claims 1 to 3, characterized in that, The additive is an amide-based slip agent.

9. A method for preparing a transparent yellow ink composition for CPP aluminized film printing as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Step S1: Mix solvent A, transparent yellow pigment and orange pigment according to the specified ratio, and stir at 20-30℃ for 20-40 minutes to obtain a mixed color paste; Step S2: Add solvent B, acrylic resin A, and acrylic resin B to the mixed color paste obtained in step S1, and stir and disperse at 800-1200 rpm for 20-40 minutes at 20-30°C. Step S3: Add adhesion promoter and additive to the product of step S2, and stir and disperse at 700-1000 rpm for 15-30 min at 20-30℃; Step S4: Grind and disperse the product from step S3 in a horizontal sand mill until the fineness is ≤10μm; Step S5: Add solvent A and / or solvent B as needed, adjust the viscosity to 25-35 seconds at 25°C and a No. 4 cup, filter the material to obtain the transparent yellow ink composition.

10. A method for preparing a transparent yellow ink composition for CPP aluminized film printing according to claim 9, characterized in that, The stirring time in step S1 is 30 minutes and the stirring temperature is 25°C; the stirring and dispersing time in step S2 is 30 minutes, the stirring temperature is 25°C, and the stirring speed is 1000 rpm; the stirring and dispersing time in step S3 is 20 minutes, the stirring temperature is 25°C, and the stirring speed is 850 rpm.

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