Micro-nano embossment structure directly-pressed paper and preparation method thereof

Abstract

The invention discloses a micro-nano embossment structure directly-pressed paper and a preparation method thereof. The preparation method comprises the following steps: A, preparing a body paper layer and a micro-nano embossment master mask; b, coating UV gloss oil on the smooth surface of the raw paper layer; pressing the micro-nano embossment mother set on the top of the UV gloss oil coating for UV mould pressing curing, stripping the micro-nano embossment mother set, and then carrying out corona treatment to obtain a UV gloss oil layer with a micro-nano embossment structure; c, aluminizing the UV gloss oil layer of the paper with the micro-nano embossment structure; d, coating the aluminum layer with water-based resin to obtain a printing ink adhesion layer; e, coating the non-smooth surface of the raw paper layer with water-based acrylic resin to obtain a closed back coating layer; f, curing treatment. According to the scheme, by using the specific raw paper layer, coating and mould pressing of the micro-nano embossment structure can be directly carried out on the surface of the paper, the image-text presentation requirement of the micro-nano embossment structure is met, a plastic film does not need to be used as an intermediate carrier, more raw materials are saved, the use of the plastic film is reduced, and the production process is more environment-friendly and simpler.

Description

Technical Field

[0001] The invention relates to the technical field of packaging materials, and in particular to a micro-nano relief structure direct-pressed paper and a preparation method thereof. Background Art

[0002] As an optical texture structure, micro-nano relief structure is realized through graphic design and high-precision laser lithography. It is named because the size of the graphic structure is in the micrometer and nanometer levels. Micro-nano structure has a rich sense of layering and is loved by the packaging industry. It is one of the most popular optical technologies at present. With the continuous maturity of technology, many label printing companies have gradually introduced relief technology to enhance the market competitiveness and differentiation needs of their products.

[0003] In the packaging materials industry, the presentation of micro-nano embossed paper is to use the micro-nano embossed master to transfer the micro-nano embossed structure information to the plastic film (such as PET film, PP film, etc.) through the molding process, and then make it into micro-nano structure paper through aluminum plating, compounding and other processes. For detailed steps, please refer to the Chinese invention patent "A positioning embossed anti-counterfeiting direct plating label paper and its preparation method" with the publication number CN117604814A. The above process requires plastic film as an intermediate carrier to perfectly present the micro-nano structure graphics, which increases material costs and requires additional compounding processes. Summary of the invention

[0004] The purpose of the present invention is to propose a micro-nano relief structure direct-pressed paper and a preparation method thereof. By using a specific base paper layer, the micro-nano relief structure can be directly molded on the surface of a UV varnish layer, and the graphic presentation requirements of the micro-nano relief structure are met. There is no need to use a plastic film as an intermediate carrier, the use of raw materials is more economical, the use of plastic film is reduced, and the preparation method is more environmentally friendly and simple.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] A method for preparing micro-nano relief structure direct-pressed paper comprises the following steps:

[0007] A. Prepare a base paper layer and a micro-nano relief master; wherein the base paper layer has a surface smoothness of ≥5000s, a transparency of ≥70%, and a COBB water absorption value of ≤6g / m3 in 30 minutes. 2 ;

[0008] B. Applying UV varnish on the glossy surface of the base paper layer to obtain a UV varnish coating; pressing the micro-nano relief master on the top of the UV varnish coating to perform UV molding curing, peeling off the micro-nano relief master and performing corona treatment to obtain a UV varnish layer; wherein a micro-nano relief structure is provided on the upper part of the UV varnish layer;

[0009] C. Aluminum is plated on the top of the UV varnish layer to obtain an aluminum layer;

[0010] D. coating a water-based resin on the top of the aluminum layer, and curing it after drying to obtain an ink adhesion layer;

[0011] E. coating a water-based acrylic resin on the non-glossy surface of the base paper layer, and curing the resin after drying to obtain a closed back coating;

[0012] F. After aging treatment, direct-pressed paper with micro-nano relief structure is obtained.

[0013] Preferably, in step A, the base paper layer has a grammage of 60 to 120 g / m 2 , fiber content ≥30wt%, thermal shrinkage deformation rate ≤2%, surface dyne value ≥38dyn.

[0014] Preferably, in step B, the UV molding curing has a molding speed of 20 to 80 m / min, a molding pressure of 5 to 15 kg, and a power of a UV lamp for curing of 7.5 to 20 kW.

[0015] Preferably, in step B, the thickness of the UV varnish layer is 4 to 12 μm, and the height difference of the concave and convex of the micro-nano relief structure is 2 to 12 μm.

[0016] Preferably, the aluminum layer has a thickness of 200 to 400 angstroms, and the aluminum layer is provided with an anti-counterfeiting pattern.

[0017] Preferably, in step D, the drying temperature is ≤110°C; and in step E, the drying temperature is ≤90°C.

[0018] Preferably, in step D, the thickness of the ink adhesion layer is 0.5-1.5 μm.

[0019] Preferably, in step E, the thickness of the closed back coating layer is 0.5-2 μm.

[0020] Preferably, in step F, the aging temperature of the aging treatment is 25-30° C., the aging humidity is 45-65%, and the aging time is ≥24 h.

[0021] A micro-nano relief structure direct-pressed paper, prepared using the above-mentioned method for preparing the micro-nano relief structure direct-pressed paper;

[0022] The micro-nano relief structure direct-pressed paper consists of a closed back coating layer, a base paper layer, a UV varnish layer, an aluminum layer and an ink adhesion layer which are arranged in sequence from bottom to top, and a micro-nano relief structure is arranged on the upper part of the UV varnish layer.

[0023] The technical solution provided by the present invention may include the following beneficial effects:

[0024] 1. This solution uses a specific base paper layer to directly mold the micro-nano relief structure on the surface of the UV varnish layer, and meets the requirements for graphic presentation of the micro-nano relief structure. There is no need to use plastic film as an intermediate carrier, which saves raw materials, reduces the use of plastic film, and makes the production process more environmentally friendly and simple.

[0025] 2. The base paper layer used in this scheme has the flatness, transparency and low water absorption of the plastic film. On the premise of meeting the graphic presentation requirements of the micro-nano relief structure, the material is plastic-free, recyclable and repulpable for papermaking, compostable and degradable, and environmentally friendly.

[0026] 3. This scheme uses the UV varnish layer as the bearing layer of the micro-nano relief structure. On the one hand, it has good adhesion to the base paper layer. On the other hand, when the micro-nano relief structure is pressed on the surface of the UV varnish layer by molding through the master plate, the UV varnish layer can be smoothly peeled off from the master plate, avoiding deformation of the graphic structure during peeling, which is more conducive to the information display of the micro-nano relief structure in the UV varnish layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the hierarchical structure of a micro-nano relief structure direct-pressed paper of the present invention.

[0028] Among them: a closed back coating layer 1, a base paper layer 2, a UV varnish layer 3, a micro-nano relief structure 301, an aluminum layer 4, and an ink adhesion layer 5. DETAILED DESCRIPTION

[0029] A method for preparing micro-nano relief structure direct-pressed paper comprises the following steps:

[0030] A. Prepare a base paper layer 2 and a micro-nano relief master; wherein the base paper layer 2 has a surface smoothness of ≥5000s, a transparency of ≥70%, and a COBB water absorption value of ≤6g / m3 in 30 minutes. 2 ;

[0031] B. Applying UV varnish on the glossy surface of the base paper layer to obtain a UV varnish coating; pressing the micro-nano relief master on the top of the UV varnish coating to perform UV molding curing, peeling off the micro-nano relief master and performing corona treatment to obtain a UV varnish layer; wherein a micro-nano relief structure is provided on the upper part of the UV varnish layer; wherein a micro-nano relief structure 301 is provided on the upper part of the UV varnish layer 3;

[0032] C. Aluminum is plated on the top of the UV varnish layer 3 to obtain an aluminum layer 4;

[0033] D. coating a water-based resin on the top of the aluminum layer 4, drying and curing to obtain an ink adhesion layer 5;

[0034] E. coating a water-based acrylic resin on the non-glossy surface (i.e., the back of the paper) of the base paper layer 2, and curing the resin after drying to obtain a closed back coating layer 1;

[0035] F. After aging treatment, direct-pressed paper with micro-nano relief structure is obtained.

[0036] Due to the use of the base paper layer in the label paper with micro-nano relief structure in the prior art, the presentation of the micro-nano relief structure requires a plastic film as an intermediate carrier to perfectly present the micro-nano structure graphics, which increases material costs and requires additional composite processes.

[0037] Therefore, in order to overcome the shortcomings of the prior art, the present technical solution proposes a method for preparing a micro-nano relief structure direct pressure paper, the hierarchical structure diagram of which is shown in FIG. Figure 1 As shown, by using a specific base paper layer 2, the micro-nano relief structure can be directly molded on the surface of the UV varnish layer 3, and the graphic presentation requirements of the micro-nano relief structure are met, and there is no need to use a plastic film as an intermediate carrier, which saves more raw materials, reduces the use of plastic film, and makes the preparation method more environmentally friendly and simple. Specifically, the base paper layer 2 used in this solution has the flatness, transparency and low water absorption of a plastic film. On the premise of meeting the graphic presentation requirements of the micro-nano relief structure, the material is plastic-free, recyclable and repulpable for papermaking, compostable and degradable, and environmentally friendly.

[0038] Furthermore, the present solution utilizes the UV varnish layer 3 as the bearing layer of the micro-nano relief structure 301. On the one hand, the adhesion strength between the UV varnish layer 3 and the base paper layer 2 is good. On the other hand, when the micro-nano relief structure 301 is pressed on the surface of the UV varnish layer 3 by molding through a master plate, the UV varnish layer 3 can be smoothly peeled off from the master plate, avoiding deformation of the graphic structure during peeling, which is more conducive to the information display of the micro-nano relief structure 301 in the UV varnish layer 3.

[0039] Further, in step A, the base paper layer 2 has a gram weight of 60 to 120 g / m 2 , fiber content ≥30wt%, thermal shrinkage deformation rate ≤2%, surface dyne value ≥38dyn.

[0040] In addition, the present solution also specifically optimizes the grammage, fiber content, thermal shrinkage deformation rate and surface dyne value of the base paper layer 2, which is more conducive to the three-dimensional presentation of the micro-nano relief structure 301 in the direct-pressed paper.

[0041] To further illustrate, in step B, the UV molding curing has a molding speed of 20 to 80 m / min, a molding pressure of 5 to 15 kg, and a power of a UV lamp for curing of 7.5 to 20 kW.

[0042] Furthermore, this solution also optimizes the molding speed of UV molding curing to avoid the UV varnish leveling not being timely due to the too fast speed, resulting in insufficient restoration of the micro-nano relief structure, white inverted triangles and surface defects. At the same time, the molding pressure is controlled to ensure that the graphic information of the micro-nano relief master is fully pressed and contacted with the UV varnish coating, so that the graphic information is completely copied to the coating. Finally, the curing power is also optimized to facilitate the full curing of the UV varnish coating, avoiding excessive UV output power leading to over-baking and brittle deformation of the paper.

[0043] To further illustrate, in step B, the thickness of the UV varnish layer 3 is 4-12 μm, and the height difference of the concave-convex of the micro-nano relief structure 301 is 2-12 μm.

[0044] In addition, in order to fully cure the UV varnish layer 3 and prevent the direct-pressed paper from becoming brittle and deformed after being irradiated by UV, the present solution also optimizes the thickness of the UV varnish layer 3. At the same time, the height difference of the micro-nano relief structure 301 is optimized to ensure the three-dimensional effect of the micro-nano relief structure 301.

[0045] To further illustrate, the thickness of the aluminum layer 4 is 200-400 angstroms, and the aluminum layer 4 is provided with an anti-counterfeiting pattern.

[0046] In a specific embodiment, an anti-counterfeiting aluminum plating machine can be used for aluminum plating, and the thickness of the aluminum layer 4 should not be too thick, and is controlled at 200 to 400 angstroms. The naked eye visibility of the image under natural light can be controlled by adjusting the thickness of the aluminum layer 4. This anti-counterfeiting aluminum plating process can enhance the metallic luster brightness of the product and provide anti-counterfeiting protection for the product.

[0047] To further illustrate, in step D, the drying temperature is ≤110°C; in step E, the drying temperature is ≤90°C.

[0048] This solution also optimizes the drying temperature of steps D and E to prevent the coating from overheating and turning white at high temperatures, thereby affecting the transparency of the paper.

[0049] To further illustrate, in step D, the thickness of the ink adhesion layer 5 is 0.5-1.5 μm.

[0050] The ink adhesion layer 5 of the present solution provides excellent adhesion for the ink during printing, and also provides friction resistance. Its thickness is preferably 0.5 to 1.5 μm, which has little effect on the brightness of the aluminum layer 4, and can effectively meet the adhesion fastness requirements of UV offset ink, ordinary offset ink, and gravure ink.

[0051] To further illustrate, in step E, the thickness of the closed back coating layer 1 is 0.5-2 μm.

[0052] This solution also optimizes the thickness of the closed back coating layer 1, which can seal the back of the base paper layer 2 and balance the stress on the front side of the paper, reduce the possibility of bending of the base paper layer 2, and ensure the flatness of the finished direct-pressed paper.

[0053] Further, in step F, the aging temperature of the aging treatment is 25-30° C., the aging humidity is 45-65%, and the aging time is ≥ 24 hours. This is beneficial to maintaining the moisture balance of the paper.

[0054] A micro-nano relief structure direct-pressed paper, prepared using the above-mentioned method for preparing the micro-nano relief structure direct-pressed paper;

[0055] The micro-nano relief structure direct-pressed paper consists of a closed back coating layer 1, a base paper layer 2, a UV varnish layer 3, an aluminum layer 4 and an ink adhesion layer 5 which are arranged in sequence from bottom to top, and a micro-nano relief structure 301 is arranged on the upper part of the UV varnish layer 3.

[0056] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0057] Example 1

[0058] A. Prepare a base paper layer 2 and a micro-nano relief master; wherein the base paper layer 2 has a surface smoothness of 5000s, a transparency of 70%, and a 30-minute COBB water absorption value of 6g / m 2 , weight 60g / m 2 , fiber content is 30wt%, thermal shrinkage deformation rate is 2%, and surface dyne value is 38dyn.

[0059] B. Apply UV varnish on the glossy surface of the base paper layer 2 to obtain a UV varnish coating; press the micro-nano relief master onto the top of the UV varnish coating for UV molding curing, peel off the micro-nano relief master and perform corona treatment to obtain a UV varnish layer with a micro-nano relief structure 301; wherein the molding speed of UV molding curing is 20m / min, the molding pressure is 5kg, the power of the UV lamp for curing is 7.5kW, the thickness of the UV varnish layer 3 is 4μm, and the concave-convex height difference of the micro-nano relief structure 301 is 2μm.

[0060] C. Aluminum is plated on the top of the UV varnish layer 3 to obtain an aluminum layer 4 with a thickness of 200 angstroms;

[0061] D. coating a water-based resin on the top of the aluminum layer 4, drying at 100° C. and curing to obtain an ink adhesion layer 5 with a thickness of 0.5 μm;

[0062] E. coating the non-glossy surface of the base paper layer 2 with a water-based acrylic resin, drying at 90° C. and curing to obtain a closed back coating layer 1 with a thickness of 0.5 μm;

[0063] F. After aging for 24 hours in an environment of temperature of 25° C. and humidity of 45%, a micro-nano relief structure direct-pressed paper is obtained.

[0064] Example 2

[0065] A. Prepare a base paper layer 2 and a micro-nano relief master; wherein the base paper layer 2 has a surface smoothness of 6000s, a transparency of 75%, and a 30-minute COBB water absorption value of 5g / m 2 , weight 90g / m 2 , fiber content is 40wt%, thermal shrinkage deformation rate is 1.5%, and surface dyne value is 40dyn.

[0066] B. Apply UV varnish on the glossy surface of the base paper layer 2 to obtain a UV varnish coating; press the micro-nano relief master onto the top of the UV varnish coating for UV molding curing, peel off the micro-nano relief master and perform corona treatment to obtain a UV varnish layer with a micro-nano relief structure 301; wherein the molding speed of UV molding curing is 50m / min, the molding pressure is 10kg, the power of the UV lamp for curing is 10kW, the thickness of the UV varnish layer 3 is 8μm, and the concave-convex height difference of the micro-nano relief structure 301 is 6μm.

[0067] C. Aluminum is plated on the top of the UV varnish layer 3 to obtain an aluminum layer 4 with a thickness of 280 angstroms;

[0068] D. coating a water-based resin on the top of the aluminum layer 4, drying at 100° C. and curing to obtain an ink adhesion layer 5 with a thickness of 1 μm;

[0069] E. coating the non-glossy surface of the base paper layer 2 with a water-based acrylic resin, drying at 90° C. and curing to obtain a closed back coating layer 1 with a thickness of 1 μm;

[0070] F. After aging for 25 hours in an environment of temperature 27° C. and humidity 55%, a micro-nano relief structure direct-pressed paper is obtained.

[0071] Example 3

[0072] A. Prepare a base paper layer 2 and a micro-nano relief master; wherein the base paper layer 2 has a surface smoothness of 5500s, a transparency of 80%, and a 30-minute COBB water absorption value of 4g / m 2 , weight 120g / m 2 , fiber content is 45wt%, thermal shrinkage deformation rate is 1%, and surface dyne value is 42dyn.

[0073] B. Apply UV varnish on the glossy surface of the base paper layer 2 to obtain a UV varnish coating; press the micro-nano relief master onto the top of the UV varnish coating for UV molding curing, peel off the micro-nano relief master and perform corona treatment to obtain a UV varnish layer with a micro-nano relief structure 301; wherein the molding speed of UV molding curing is 80m / min, the molding pressure is 15kg, the power of the UV lamp for curing is 20kW, the thickness of the UV varnish layer 3 is 12μm, and the concave-convex height difference of the micro-nano relief structure 301 is 11μm.

[0074] C. Aluminum is plated on the top of the UV varnish layer 3 to obtain an aluminum layer 4 with a thickness of 380 angstroms;

[0075] D. coating a water-based resin on the top of the aluminum layer 4, drying at 100° C. and curing to obtain an ink adhesion layer 5 with a thickness of 1.5 μm;

[0076] E. coating the non-glossy surface of the base paper layer 2 with a water-based acrylic resin, drying at 90° C. and curing to obtain a closed back coating layer 1 with a thickness of 2 μm;

[0077] F. After aging for 24 hours in an environment of temperature of 30° C. and humidity of 65%, a micro-nano relief structure direct-pressed paper is obtained.

[0078] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods will fall within the scope of protection of the present invention.

Claims

1. A method for preparing micro-nano relief structure direct-pressed paper, characterized in that: The following steps are involved: A. Prepare a base paper layer and a micro-nano relief master; wherein the base paper layer has a surface smoothness of ≥5000s, a transparency of ≥70%, and a COBB water absorption value of ≤6g / m3 in 30 minutes. 2 ; B. Applying UV varnish on the glossy surface of the base paper layer to obtain a UV varnish coating; pressing the micro-nano relief master on the top of the UV varnish coating to perform UV molding curing, peeling off the micro-nano relief master and performing corona treatment to obtain a UV varnish layer; wherein a micro-nano relief structure is provided on the upper part of the UV varnish layer; C. Aluminum is plated on the top of the UV varnish layer to obtain an aluminum layer; D. coating a water-based resin on the top of the aluminum layer, and curing it after drying to obtain an ink adhesion layer; E. coating a water-based acrylic resin on the non-glossy surface of the base paper layer, and curing the resin after drying to obtain a closed back coating; F. After aging treatment, direct-pressed paper with micro-nano relief structure is obtained.

2. The method for preparing a micro-nano relief structure direct-pressed paper according to claim 1, characterized in that: In step A, the base paper layer has a grammage of 60 to 120 g / m 2 , fiber content ≥30wt%, thermal shrinkage deformation rate ≤2%, surface dyne value ≥38dyn.

3. The method for preparing a micro-nano relief structure direct-pressed paper according to claim 1, characterized in that: In step B, the UV molding curing has a molding speed of 20 to 80 m / min, a molding pressure of 5 to 15 kg, and a power of a UV lamp for curing of 7.5 to 20 kW.

4. The method for preparing a micro-nano relief structure direct-pressed paper according to claim 1, characterized in that: In step B, the thickness of the UV varnish layer is 4-12 μm, and the height difference of the concave-convex of the micro-nano relief structure is 2-12 μm.

5. The method for preparing a micro-nano relief structure direct-pressed paper according to claim 1, characterized in that: The thickness of the aluminum layer is 200-400 angstroms, and the aluminum layer is provided with an anti-counterfeiting pattern.

6. The method for preparing a micro-nano relief structure direct-pressed paper according to claim 1, characterized in that: In step D, the drying temperature is ≤110°C; in step E, the drying temperature is ≤90°C.

7. The method for preparing a micro-nano relief structure direct-pressed paper according to claim 1, characterized in that: In step D, the thickness of the ink adhesion layer is 0.5-1.5 μm.

8. The method for preparing a micro-nano relief structure direct-pressed paper according to claim 1, characterized in that: In step E, the thickness of the closed back coating layer is 0.5-2 μm.

9. The method for preparing a micro-nano relief structure direct-pressed paper according to claim 1, characterized in that: In step F, the aging temperature of the aging treatment is 25-30° C., the aging humidity is 45-65%, and the aging time is ≥24 hours.

10. A micro-nano relief structure direct-pressed paper, characterized in that: Prepared by the method for preparing micro-nano relief structure direct pressure paper according to any one of claims 1 to 9; The micro-nano relief structure direct-pressed paper consists of a closed back coating layer, a base paper layer, a UV varnish layer, an aluminum layer and an ink adhesion layer which are arranged in sequence from bottom to top, and a micro-nano relief structure is arranged on the upper part of the UV varnish layer.

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