A waterproof and scratch-resistant coating for labels, its preparation method, and a self-adhesive label

Abstract

The present invention relates to the technical field of coating preparation, and specifically discloses a waterproof and scratch-resistant coating for labels, a preparation method thereof, and a self-adhesive label. A waterproof and scratch-resistant coating for labels comprises 20 to 30 parts of polyvinyl alcohol, 35 to 50 parts of acrylate, 2 to 5 parts of ethylene versatate, 1 to 2.5 parts of propylene glycol methyl ether acetate, 0.5 to 1.5 parts of glycidyl bisphenol fluorene acrylate, 1.5 to 3 parts of a thickener, 1.5 to 3 parts of an emulsifier, and 10 to 15 parts of deionized water. A method for preparing a waterproof and scratch-resistant coating for labels comprises mixing the components to obtain a waterproof and scratch-resistant coating for labels. A self-adhesive label comprises using the waterproof and scratch-resistant coating for labels of the present application as a protective layer. The present application can give self-adhesive labels good waterproofness and scratch resistance, further improving the working performance of self-adhesive labels.

Description

Technical Field

[0001] The present invention relates to the technical field of coating preparation, in particular to a waterproof and scratch-resistant coating for labels, a preparation method thereof, and a self-adhesive label. Background Art

[0002] Self-adhesive labels typically use a paper, film, or other substrate as the top layer, with a layer of glue applied to the back. A release paper liner is used as the backing layer. After printing and die-cutting, the finished label is simply peeled from the backing paper and affixed to the surface of various products. They are also suitable for automated labeling on assembly lines. When self-adhesive labels use a paper substrate as the top layer, they are typically covered with a protective layer of plastic film (such as PP or PE) over the pre-printed paper. This protective layer imparts excellent water resistance and abrasion resistance, making them widely used in packaging for food, fast-moving consumer goods, and other applications.

[0003] However, the surface tension of PP, PE and other plastic films is too low, which directly leads to the low adhesion of PP, PE and other plastic films to the ink covered on the paper substrate. If PP, PE and other plastic films are not specially treated, directly covering a layer of PP, PE and other plastic films on the paper substrate may cause the ink and the protective layer to not fit together, resulting in blurred label content and unattractive appearance. In severe cases, it may cause the PP, PE and other plastic films to fall off.

[0004] In the prior art, to ensure that plastic films such as PP and PE can adhere stably to paper substrates, a layer of adhesive is generally first applied to the PP or PE film, which is then used to stably adhere the film to the paper substrate. During this lamination process, the PP or PE film may suffer irreversible damage such as scratches and abrasions, which may affect the final protective layer. Furthermore, this lamination method requires extremely high flatness of the paper substrate. If the paper substrate is not flat, the resulting protective layer is prone to bubbles, ripples, and other patterns. However, many existing labels are made with uneven paper substrates to attract attention, or use three-dimensional printing to print patterns or text with a certain ink thickness on the paper substrate, which further increases the difficulty of using plastic films such as PP and PE as protective layers.

[0005] In view of the above-mentioned related technologies, the inventors believe that it is necessary to further improve the protective layer of the self-adhesive label. Summary of the Invention

[0006] To further improve the protective layer of self-adhesive labels, the present application provides a waterproof and scratch-resistant coating for labels, a preparation method thereof, and a self-adhesive label. The waterproof and scratch-resistant coating for labels prepared in the present application exhibits excellent adhesion, water resistance, and scratch resistance. When applied to a paper substrate, the waterproof and scratch-resistant coating for labels not only forms a transparent, conformable protective layer on the surface of the paper substrate, but also imparts excellent water resistance and scratch resistance to the self-adhesive label, further improving the performance of the self-adhesive label.

[0007] In the first aspect, the present application provides a waterproof and scratch-resistant coating for labels using the following technical solutions:

[0008] A waterproof and scratch-resistant coating for labels, comprising the following raw materials in parts by mass:

[0009] Polyvinyl alcohol: 20-30 parts;

[0010] Acrylate: 35-50 parts;

[0011] Versatile vinyl carbonate: 2-5 parts;

[0012] Propylene glycol methyl ether acetate: 1-2.5 parts;

[0013] Glycidyl bisphenol fluorene acrylate: 0.5-1.5 parts;

[0014] Thickener: 1.5-3 parts;

[0015] Emulsifier: 1.5-3 parts;

[0016] Deionized water: 10-15 parts.

[0017] In the above technical solution, by adding polyvinyl alcohol and acrylate to the waterproof and scratch-resistant coating for labels, the two cooperate with each other to have good film-forming properties, and can stably form a transparent waterproof protective layer on the paper substrate. The interaction between ethylene tertacarbonate, propylene glycol methyl ether acetate, and glycidyl bisphenol fluorene acrylate can further modify the waterproof and scratch-resistant coating for labels, significantly improve the surface smoothness of the waterproof and scratch-resistant coating for labels, give the self-adhesive label good scratch resistance, enhance the gloss of the protective layer, and further enhance the texture of the self-adhesive label.

[0018] Preferably, the mass ratio of versatate vinyl carbonate, propylene glycol methyl ether acetate, and glycidyl bisphenol fluorene acrylate is (2-3): (1.5-2.5): (0.5-1).

[0019] In the above technical solution, by limiting the mass ratio of versatate, propylene glycol methyl ether acetate, and glycidyl bisphenol fluorene acrylate to (2-3): (1.5-2.5): (0.5-1), the wear resistance and glossiness of the protective layer are further improved, and the texture of the self-adhesive label is further enhanced.

[0020] Preferably, the waterproof and scratch-resistant label coating further comprises triethanolamine, cellulose ether and cetyl ethylhexanoate; based on the mass fraction of the waterproof and scratch-resistant label coating, it comprises 1.2 to 1.7 parts of triethanolamine, 0.6 to 1.1 parts of cellulose ether and 0.4 to 0.8 parts of cetyl ethylhexanoate.

[0021] In the above technical solution, by further adding 1.2 to 1.7 parts of triethanolamine, 0.6 to 1.1 parts of cellulose ether, and 0.4 to 0.8 parts of cetyl ethylhexanoate to the waterproof and scratch-resistant label coating, the uniform dispersion of the substances in the waterproof and scratch-resistant label coating can be further promoted, and the wettability and adhesion of the waterproof and scratch-resistant label coating to the paper substrate and ink can be further promoted, thereby further improving the adhesion of the protective layer to the paper substrate and ink. When the adhesion of the ink to the paper substrate is not very good, the adhesion between the ink and the paper substrate can also be further enhanced by the waterproof and scratch-resistant label coating of this application.

[0022] Preferably, the mass ratio of triethanolamine, cellulose ether and cetyl ethylhexanoate is 1.2:1.1:0.4.

[0023] In the above technical solution, by limiting the mass ratio of triethanolamine, cellulose ether and cetyl ethylhexanoate to 1.2:1.1:0.4, the wettability and adhesion of the waterproof and scratch-resistant label coating to the paper substrate and ink are further promoted, and the adhesion of the protective layer to the paper substrate and ink is further improved.

[0024] In a second aspect, the present application provides a method for preparing a waterproof and scratch-resistant coating for labels, which adopts the following technical solution: A method for preparing a waterproof and scratch-resistant coating for labels, comprising the following steps:

[0025] Step 1: Accurately weigh the raw materials according to their mass fractions, mix deionized water, polyvinyl alcohol, and acrylate under stirring, then add tert-butyl ester, propylene glycol methyl ether acetate, and glycidyl bisphenol fluorene acrylate and mix well;

[0026] Step 2: Add a thickener and an emulsifier to the solution obtained in step 1 while stirring, and mix them evenly to obtain a waterproof and scratch-resistant coating for labels.

[0027] Preferably, the method comprises the following steps:

[0028] Step 1: Accurately weigh the raw materials according to their mass fractions, mix deionized water, polyvinyl alcohol, and acrylate under stirring, then add tert-butyl ester, propylene glycol methyl ether acetate, and glycidyl bisphenol fluorene acrylate and mix well;

[0029] Step 2: Add triethanolamine, cellulose ether, cetyl ethylhexanoate, thickener, and emulsifier to the solution obtained in step 1 while stirring, and mix well to obtain a waterproof and scratch-resistant coating for labels.

[0030] In the above technical solution, the waterproof and scratch-resistant coating system for labels prepared by the above preparation steps is stable, has good fluidity and ductility, can form a complete protective layer on the self-adhesive label paper, and gives the self-adhesive label paper good waterproofness, scratch resistance and gloss.

[0031] In a third aspect, the present application provides a self-adhesive label that adopts the following technical solution:

[0032] A self-adhesive label comprises, from bottom to top, a base paper layer, a glue layer, and a surface layer for printing. A protective layer is attached to the side of the surface layer away from the glue layer. The protective layer is a coating formed by applying the waterproof and scratch-resistant coating for the label described in the first aspect to the side of the surface layer away from the glue layer.

[0033] In the above technical solution, by applying the waterproof and scratch-resistant coating for labels to self-adhesive labels, the self-adhesive label paper can be given good waterproofness, scratch resistance and glossiness. The process is simple and the effect is obvious. It is suitable for large-scale industrial production, especially for the preparation of self-adhesive labels with uneven surfaces.

[0034] Preferably, the specific coating method of the protective layer is as follows: evenly coat the waterproof and scratch-resistant coating on the side of the surface layer away from the glue layer, and then bake at 70-80° C. for 5-8 minutes to obtain the protective layer.

[0035] In the above technical solution, by further defining the method of using the waterproof and scratch-resistant coating for labels, a complete and smooth protective layer can be better formed on the self-adhesive label, thereby further improving the waterproofness, scratch resistance and glossiness of the self-adhesive label.

[0036] In summary, this application includes at least one of the following beneficial technical effects:

[0037] 1. This application adds polyvinyl alcohol and acrylate to the waterproof and scratch-resistant coating for labels. The two cooperate with each other to have good film-forming properties and can stably form a transparent waterproof protective layer on the paper substrate. The interaction between ethylene tertacarbonate, propylene glycol methyl ether acetate, and glycidyl bisphenol fluorene acrylate can further modify the waterproof and scratch-resistant coating for labels, significantly improve the surface smoothness of the waterproof and scratch-resistant coating for labels, give the self-adhesive label good scratch resistance, enhance the gloss of the protective layer, and further enhance the texture of the self-adhesive label.

[0038] 2. By adding triethanolamine, cellulose ether, and cetyl ethylhexanoate to the waterproof and scratch-resistant label coating, the present application can further promote the uniform dispersion of various substances in the waterproof and scratch-resistant label coating and further promote the wettability and adhesion of the waterproof and scratch-resistant label coating to the paper substrate and ink, further improving the adhesion of the protective layer to the paper substrate and ink. When the adhesion of the ink to the paper substrate is not very good, the adhesion between the ink and the paper substrate can also be further enhanced by the waterproof and scratch-resistant label coating of the present application. DETAILED DESCRIPTION

[0039] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0040] Example 1

[0041] A waterproof and scratch-resistant coating for labels includes 30 kg of polyvinyl alcohol, 35 kg of acrylate, 5 kg of versatate, 1 kg of propylene glycol methyl ether acetate, 1.5 kg of glycidyl bisphenol fluorene acrylate, 1.5 kg of thickener, 3 kg of emulsifier, and 15 kg of deionized water.

[0042] Among them, the thickener is DOW TT935.

[0043] The emulsifier is Disponil FES 32.

[0044] The method for preparing a waterproof and scratch-resistant coating for a label comprises the following steps:

[0045] Step 1: Accurately weigh the raw materials according to their mass, mix deionized water, polyvinyl alcohol and acrylate under stirring at 800 r / min, then add tertasodium ethylene carbonate, propylene glycol methyl ether acetate and glycidyl bisphenol fluorene acrylate and mix well;

[0046] Step 2: Add a thickener and an emulsifier to the solution obtained in step 1 while stirring, and then stir for 10 minutes to obtain a waterproof and scratch-resistant coating for labels.

[0047] Example 2

[0048] A waterproof and scratch-resistant coating for labels, which differs from Example 1 in that it includes 20 kg of polyvinyl alcohol, 50 kg of acrylate, 2 kg of ethylene versatate, 2.5 kg of propylene glycol methyl ether acetate, 0.5 kg of glycidyl bisphenol fluorene acrylate, 3 kg of thickener, 1.5 kg of emulsifier, and 10 kg of deionized water.

[0049] Example 3

[0050] A waterproof and scratch-resistant coating for labels, which differs from Example 1 in that it includes 30 kg of polyvinyl alcohol, 35 kg of acrylate, 3 kg of versatate, 1.5 kg of propylene glycol methyl ether acetate, 1 kg of glycidyl bisphenol fluorene acrylate, 1.5 kg of thickener, 3 kg of emulsifier, and 15 kg of deionized water.

[0051] Example 4

[0052] A waterproof and scratch-resistant coating for labels, which differs from Example 3 in that it further comprises 1.7 kg of triethanolamine, 0.6 kg of cellulose ether, and 0.8 kg of cetyl ethylhexanoate.

[0053] Example 5

[0054] A waterproof and scratch-resistant coating for labels, which differs from Example 3 in that it further comprises 1.2 kg of triethanolamine, 1.1 kg of cellulose ether, and 0.4 kg of cetyl ethylhexanoate.

[0055] Example 6

[0056] A waterproof and scratch-resistant coating for labels, which differs from Example 5 in that triethanolamine is not included.

[0057] Example 7

[0058] A waterproof and scratch-resistant coating for labels, which differs from Example 5 in that it does not include cellulose ether.

[0059] Example 8

[0060] A waterproof and scratch-resistant coating for labels, which differs from Example 5 in that cetyl ethylhexanoate is not included.

[0061] Comparative Example 1

[0062] A waterproof and scratch-resistant coating for labels, which differs from Example 3 in that it does not include versatate.

[0063] Comparative Example 2

[0064] A waterproof and scratch-resistant coating for labels, which differs from Example 3 in that propylene glycol methyl ether acetate is not included.

[0065] Comparative Example 3

[0066] A waterproof and scratch-resistant coating for labels, which differs from Example 3 in that it does not contain glycidyl bisphenol fluorene acrylate.

[0067] test

[0068] Adhesion test 1:

[0069] The test method is the 100-grid test method. The test sample is a paper substrate coated with the waterproof and scratch-resistant label coating of each of the above embodiments and comparative examples. The paper substrate is glass cardboard (purchased from Dongguan Chuangcai Paper Co., Ltd., with a thickness of 0.38mm). A 100-grid cutter is used to cut 100 1mm*1mm small grids on the surface of the protective layer. Then, 600#3M tape is applied to the grids and instantly torn off. After the test is completed, the coating surface is observed for any peeling and rated. The rating criteria are as follows:

[0070] The scribe line edge is smooth and without shedding, which is 5B; the scribe line edge shedding area is between 0% and 5%, which is 4B; the scribe line edge shedding area is between 5% and 15%, which is 3B; the scribe line edge shedding area is between 15% and 35%, which is 2B; the scribe line edge shedding area is between 35% and 65%, which is 1B; the scribe line edge shedding area is greater than 65%, which is 0B. The test results are shown in Table 1.

[0071] Adhesion Test 2:

[0072] The test sample is a paper substrate coated with the waterproof and scratch-resistant coating for labels of the above-mentioned embodiments and comparative examples. The paper substrate is glass cardboard (purchased from Dongguan Chuangcai Paper Co., Ltd., with a thickness of 0.38 mm), and a layer of water-based ink is pre-printed on the paper substrate. The water-based ink is evenly distributed in a circular shape (radius 0.2 mm) on the surface of the paper substrate, occupying 50% of the surface area of the paper substrate. The rest is as in Adhesion Test 1. The test results are shown in Table 1.

[0073] Adhesion Test 3:

[0074] The test sample was a paper substrate completely pre-printed with the water-based ink of Adhesion Test 2. The paper substrate was glass cardboard (purchased from Dongguan Chuangcai Paper Co., Ltd., with a thickness of 0.38 mm). The rest of the test was the same as Adhesion Test 1. The adhesion grade of the water-based ink of Adhesion Test 2 to the paper substrate was tested, and the test result was 2B.

[0075] Flexibility test:

[0076] The flexibility of waterproof and scratch-resistant label coatings was tested in accordance with GB / T 1731-2020, Determination of Flexibility of Paint and Putty Films. The minimum rod diameter (mm) at which no reticulation, cracking, or peeling was observed after two tests was recorded. The test results are shown in Table 1.

[0077] Wear resistance test:

[0078] The abrasion resistance of waterproof and scratch-resistant label coatings was tested in accordance with GB / T 23988-2009, "Determination of Abrasion Resistance of Coatings - Falling Sand Method." The test sample was a paper substrate coated with the waterproof and scratch-resistant label coatings of the aforementioned embodiments and comparative examples. The paper substrate was glass cardboard (purchased from Dongguan Chuangcai Paper Co., Ltd., 0.38 mm thick) with a protective layer thickness of 20 μm. The amount of abrasive used was measured using an abrasion tester and the abrasion resistance (L / μm) was calculated. The larger the abrasion resistance value, the better the abrasion resistance of the silicone rubber coating. The test results are shown in Table 1.

[0079] Gloss test:

[0080] Waterproof and scratch-resistant label coatings were tested for gloss at 60°, according to GB / T 1743-1979, "Determination of Gloss of Paint Films." The test samples were paper substrates coated with the waterproof and scratch-resistant label coatings described in the aforementioned examples and comparative examples. The paper substrates were glass cardboard (purchased from Dongguan Chuangcai Paper Co., Ltd., 0.38 mm thick) with a protective layer thickness of 20 μm. A higher gloss value indicates better gloss. The test results are shown in Table 1.

[0081] Table 1:

[0082]

[0083]

[0084] Combining Examples 1-8, Comparative Examples 1-3 and Table 1, it is not difficult to see that Examples 1-8 have good adhesion, flexibility, wear resistance and gloss.

[0085] Specifically analyzing in combination with Example 3 and Comparative Examples 1-3, the difference between Example 3 and Comparative Example 1 is that Comparative Example 1 does not add tert-butyl vinyl carbonate, the difference between Example 3 and Comparative Example 2 is that Comparative Example 2 does not add propylene glycol methyl ether acetate, and the difference between Example 3 and Comparative Example 3 is that Comparative Example 3 does not add glycidyl bisphenol fluorene acrylate. Example 3 has good flexibility, wear resistance and gloss. From this analysis, the present application can further modify the waterproof and scratch-resistant coating for labels through the interaction between tert-butyl vinyl carbonate, propylene glycol methyl ether acetate and glycidyl bisphenol fluorene acrylate, significantly improve the surface smoothness of the waterproof and scratch-resistant coating for labels, give the self-adhesive label good scratch resistance, enhance the gloss of the protective layer, and further enhance the texture of the self-adhesive label.

[0086] Specifically analyzing in combination with Example 5 and Examples 6-8, the difference between Example 5 and Example 6 is that Example 6 does not add triethanolamine, the difference between Example 5 and Example 7 is that Example 7 does not add cellulose ether, and the difference between Example 5 and Example 8 is that Example 8 does not add cetyl ethylhexanoate. Example 5 has better adhesion, and the wear resistance and glossiness of Example 5 are also better to a certain extent. The inventor specifically analyzed and believed that this is because the present application can further promote the uniform dispersion of various substances in the waterproof and scratch-resistant label coating by adding triethanolamine, cellulose ether and cetyl ethylhexanoate to the waterproof and scratch-resistant label coating, thereby further improving the wear resistance and gloss of the waterproof and scratch-resistant label coating. At the same time, the interaction between triethanolamine, cellulose ether and cetyl ethylhexanoate can further promote the wettability and adhesion of the waterproof and scratch-resistant label coating to the paper substrate and ink, and further improve the adhesion of the protective layer to the paper substrate and ink.

[0087] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A waterproof and scratch-resistant coating for labels, characterized in that: The waterproof and scratch-resistant coating for labels includes the following raw materials in parts by mass: Polyvinyl alcohol: 20-30 parts; Acrylate: 35-50 parts; Versatile vinyl carbonate: 2-5 parts; Propylene glycol methyl ether acetate: 1-2.5 parts; Glycidyl bisphenol fluorene acrylate: 0.5-1.5 parts; Thickener: 1.5~3 parts; Emulsifier: 1.5~3 parts; Deionized water: 10-15 parts.

2. The waterproof and scratch-resistant coating for labels according to claim 1, characterized in that: The mass ratio of versatate vinyl carbonate, propylene glycol methyl ether acetate, and glycidyl bisphenol fluorene acrylate is (2-3): (1.5-2.5): (0.5-1).

3. The waterproof and scratch-resistant coating for labels according to claim 1, characterized in that: The waterproof and scratch-resistant coating for labels also includes triethanolamine, cellulose ether and cetyl ethylhexanoate; The waterproof and scratch-resistant coating for labels comprises 1.2 to 1.7 parts of triethanolamine, 0.6 to 1.1 parts of cellulose ether, and 0.4 to 0.8 parts of cetyl ethylhexanoate, calculated by weight.

4. The waterproof and scratch-resistant coating for labels according to claim 3, characterized in that: The mass ratio of the triethanolamine, cellulose ether and cetyl ethylhexanoate is 1.2:1.1:0.

4.

5. A method for preparing a waterproof and scratch-resistant coating for labels according to claim 1 or 2, characterized in that: The steps include: Step 1: Accurately weigh the raw materials according to their mass fractions, mix deionized water, polyvinyl alcohol, and acrylate under stirring, then add tert-butyl ester, propylene glycol methyl ether acetate, and glycidyl bisphenol fluorene acrylate and mix well; Step 2: Add a thickener and an emulsifier to the solution obtained in step 1 while stirring, and mix them evenly to obtain a waterproof and scratch-resistant coating for labels.

6. A method for preparing a waterproof and scratch-resistant coating for labels according to claim 3 or 4, characterized in that: The steps include: Step 1: Accurately weigh the raw materials according to their mass fractions, mix deionized water, polyvinyl alcohol, and acrylate under stirring, then add tert-butyl ester, propylene glycol methyl ether acetate, and glycidyl bisphenol fluorene acrylate and mix well; Step 2: Add triethanolamine, cellulose ether, cetyl ethylhexanoate, thickener, and emulsifier to the solution obtained in step 1 while stirring, and mix well to obtain a waterproof and scratch-resistant coating for labels.

7. A self-adhesive label, characterized in that: The self-adhesive label comprises, from bottom to top, a base paper layer, a glue layer, and a surface layer for printing. A protective layer is attached to the side of the surface layer away from the glue layer. The protective layer is a coating formed by applying the waterproof and scratch-resistant coating for the label according to any one of claims 1 to 4 on the side of the surface layer away from the glue layer.

8. The self-adhesive label according to claim 7, characterized in that: The specific coating method of the protective layer is as follows: the waterproof and scratch-resistant coating is evenly coated on the side of the surface layer away from the glue layer, and then baked at 70-80° C. for 5-8 minutes to obtain the protective layer.

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