A method for preparing a paper for intaglio printing and brush writing couplets

Abstract

The application discloses a preparation method of a paper suitable for intaglio printing and brush writing, and comprises the following steps: step (1), pulp preparation: bleached kraft softwood chemical pulp and bleached kraft hardwood chemical pulp are proportioned at a ratio of 5-10% and 90-95%; step (2), beating: the NBKP beating degree is controlled to be 38-48SR to provide good fiber bonding force and paper strength; the LBKP beating degree is controlled to be 25-35SR to provide excellent paper forming uniformity, smoothness and softness; step (3), sizing: carboxymethyl modified starch is added to the pulp before a paper machine pressure screen; step (4), pulp washing, sand and gas removal and sizing: step (5), fine screening, net section dewatering forming, pressing and pre-drying, to obtain raw paper: step (6), surface coating. The paper prepared by the method has excellent printing performance, excellent writing experience and excellent comprehensive quality, and the process is advanced.

Description

Technical Field

[0001] This invention relates to the field of papermaking, and in particular to a method for preparing paper suitable for gravure printing and calligraphy couplets. Background Technology

[0002] Traditional festival items such as couplets and New Year pictures are usually printed on red paper using gravure printing and calligraphy. Currently, most of the paper on the market is ordinary uncoated red paper or simply coated paper, which has many defects: (1) Poor printing effect: Ordinary paper has a rough surface and low smoothness, which leads to insufficient ink transfer during gravure printing, loss of halftone dots, blurry edges of patterns and text, and lack of exquisiteness and gloss. (2) Poor writing suitability: When writing with a brush, the ink is prone to "bleeding" (ink bleeding), and the edges of the characters are rough and not clear and sharp enough; at the same time, due to the paper structure, the ink dries slowly and is easy to stain. (3) Insufficient paper stiffness and feel: It is difficult to achieve the required texture, which affects the hanging effect and product grade.

[0003] While existing technologies can improve some properties through coating, traditional coating formulations (such as those using coating starch or conventional adhesives) often struggle to achieve a balance between print gloss, writing drying speed, ink bleed resistance, and coating handling performance.

[0004] Therefore, there is an urgent need to develop a new paper manufacturing method to produce specialized paper that can simultaneously meet the needs of high-end gravure printing and traditional brush writing. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preparing paper suitable for gravure printing and calligraphy writing of couplets. The resulting paper possesses extremely high smoothness, gloss, and surface strength, resulting in exquisite gravure printing effects. Simultaneously, it exhibits excellent suitability for calligraphy writing, with high gloss in the characters, non-water-absorbing properties, and easy drying. Furthermore, the paper has good stiffness, making it suitable for use in traditional festival items such as couplets and New Year paintings. The technical solution provided by this invention is as follows: A method for preparing paper suitable for gravure printing and calligraphy couplets includes the following steps: Step (1) Pulp preparation: Mix bleached sulfate softwood chemical pulp (NBKP) and bleached sulfate hardwood chemical pulp (LBKP) at a ratio of 5-10% and 90-95% respectively; Step (2) beating: NBKP beating degree is controlled at 38-48°SR to provide good fiber bonding and paper strength; LBKP beating degree is controlled at 25-35°SR to provide excellent paper forming uniformity, smoothness and softness; Step (3) Seasoning: Add carboxymethyl modified starch (CMS) to the slurry; Step (4) Grouting, sand and air removal, and grouting: Step (5) Fine screening, wire section dewatering and forming, pressing, and pre-drying are used to obtain the base paper: Step (6) Surface coating: Mix the following components in the indicated weight ratios to obtain the coating: Pigment: 100 parts flaky kaolin; Adhesive: 0.5-1.2 parts of carboxyl-modified PVA, 6-10 parts of styrene-butadiene latex; Water-retaining agent: 0.3-0.5 parts of modified alkali-swellable acrylic acid; Additives: 0.2-0.4 parts of polyether-modified polysiloxane; Dispersant: 0.015-0.022 parts; Defoamer: 0.008-0.012 parts; Then, the base paper is coated on one side using a doctor blade coating method; After step (7), the product is dried, calendered, rolled up, and packaged.

[0006] The carboxymethyl modified starch (CMS) is a white or light yellow powder with a degree of substitution (DS) of 0.4-0.6, a solid content of ≥90%, a viscosity (25℃) of 800-1500 mPa·s in a 2% aqueous solution, and a pH value (1% aqueous solution) of 8.0-10.0.

[0007] In step (3), the amount of carboxymethyl modified starch added is 1-3 kg / ton of slurry.

[0008] The raw material components of the coating include: Pigment: 100 parts flaky kaolin; Adhesive: 0.8 parts carboxyl-modified PVA, 8 parts styrene-butadiene latex; Water-retaining agent: 0.3 parts of modified alkali-swellable acrylic acid; Additive: 0.3 parts of polyether-modified polysiloxane; Dispersant: 0.02 parts; Defoamer: 0.01 parts.

[0009] In step (6), the coating amount is 10-15 g / m².

[0010] The carboxyl-modified PVA is a white powder with a solid content ≥90%, a degree of alcoholysis of 93-95 mol%, a viscosity (20℃) of 25-35 mPa·s for a 4% aqueous solution, and a pH value (4% aqueous solution) of 5.0-7.0.

[0011] The styrene-butadiene latex is a white emulsion with a solid content of 48-52%, a Brookfield viscosity (25℃, 60rpm) of <300mPa·s, a pH value of 7.0-9.0, and a bound styrene content of 60-70%.

[0012] The modified alkali-swellable acrylic acid is a milky white emulsion with a solid content of 28-32% and a pH value of 2.5-4.5.

[0013] The polyether-modified polysiloxane is a transparent to semi-transparent liquid with an effective ingredient content of 100%, a viscosity (25°C) of 500-1500 mPa·s, and a pH value of approximately neutral 6.0-8.0.

[0014] The specific calendering process parameters are: soft calendering, linear pressure of 100-150 kN / m, temperature of 70-90℃, preferably linear pressure of 120 kN / m and temperature of 80℃.

[0015] Compared with the prior art, the preparation method of the present invention for gravure printing and calligraphy couplet paper includes the following steps: Step (1) Pulp preparation: Bleached sulfate softwood chemical pulp (NBKP) and bleached sulfate hardwood chemical pulp (LBKP) are prepared in proportions of 5-10% and 90-95% respectively; Step (2) Beating: The beating degree of NBKP is controlled at 38-48°SR to provide good fiber bonding and paper strength; the beating degree of LBKP is controlled at 25-35°SR to provide excellent paper forming uniformity, smoothness and softness; Step (3) Conditioning: Adding to the pulp before the pressure screen of the paper machine Carboxymethyl modified starch (CMS); Step (4) Slurrying, sand removal and degassing, sizing: Step (5) Fine screening, wire dewatering and forming, pressing, pre-drying, to obtain base paper: Step (6) Surface coating: Mix the following components in weight ratio to obtain coating: Pigment: 100 parts of flake kaolin, Adhesive: Carboxymethyl modified PVA 0.5-1.2 parts, Styrene-butadiene latex 6-10 parts, Water retention agent: Modified alkali-swellable acrylic acid 0.3-0.5 parts, Additives: Polyether modified polysiloxane 0.2-0.4 parts, Dispersant and defoamer, and then use a doctor blade coating method to coat the base paper on one side; Step (7) Post-drying, calendering, winding, and packaging. The main technical parameters of the couplet paper obtained by this invention are as follows: basis weight: 80-120g / m², paper ink absorption (K&N value): 29-35%, paper surface gloss: 65-80%, printing gloss: 90-99%, surface strength (wax stick value): ≥1.0m / s, smoothness: ≥1200s, roughness: ≤1.2μm, breaking length: ≥5000m, ISO whiteness: 84-86%ISO (can be used as base paper, which is convenient for subsequent dyeing into red or other colors).

[0016] The beneficial effects of this invention are as follows: 1. Superior printing performance: Extremely low roughness (≤1.2μm) and high smoothness (≥1200s) enable the fine dots of gravure printing to be perfectly reproduced. The printing gloss (90-99%) far exceeds that of ordinary red paper, resulting in exquisite patterns and bright colors.

[0017] 2. Superior writing experience: By precisely controlling the ink absorption of polyether-modified polysiloxane, the problem of "water leakage" and slow drying when writing on ordinary red paper with a brush is completely solved.

[0018] 3. Excellent overall quality: The paper has excellent surface strength, a good feel, good durability, and its overall quality and grade are significantly higher than ordinary products.

[0019] 4. Advanced technology: The innovative coating formula (no starch coating, using modified acrylic and PVA) solves the problems of poor leveling and easy flocculation of traditional coatings, ensuring production stability and coating uniformity. Attached Figure Description

[0020] Figure 1 This is a comparison image of the printing effect on ordinary coated paper. Figure 2 This is a printing effect diagram of the couplet paper in Example 1. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] Source of materials Carboxymethyl modified starch (CMS) is a white or pale yellow powder with a degree of substitution (DS) of 0.4-0.6, a solid content of ≥90%, a viscosity (25℃) of 800-1500 mPa·s in a 2% aqueous solution, and a pH value (1% aqueous solution) of 8.0-10.0.

[0023] Water-retaining agent: Modified alkali-swellable acrylic acid; Additive: Polyether-modified polysiloxane; The remaining materials are sourced from commercially available sources.

[0024] Example 1 Make couplet paper using the following method.

[0025] Step (1) Pulp preparation: Mix bleached sulfate softwood chemical pulp (NBKP) and bleached sulfate hardwood chemical pulp (LBKP) at a ratio of 8% and 92% respectively; Step (2) Pulping: NBKP and LBKP are pulped separately. The NBKP pulping degree is controlled at 40°SR to provide good fiber bonding and paper strength; the LBKP pulping degree is controlled at 30°SR to provide excellent paper forming uniformity, smoothness and softness. Step (3) Seasoning: Add 2 kg / ton of oven-dried slurry carboxymethyl modified starch (CMS) to the slurry. Step (4) Grouting, sand and air removal, and grouting: Step (5) involves fine screening, wire dewatering and forming, pressing, and pre-drying to obtain base paper with a weight of 90 g / m². Step (6) Surface coating: Mix the following components in the indicated weight ratios to obtain a coating with a solid content of 62% and a viscosity of 925 mPa·s: Pigment: 100 parts flaky kaolin; Adhesive: 0.8 parts carboxyl-modified PVA, 8 parts styrene-butadiene latex; Water-retaining agent: 0.3 parts of modified alkali-swellable acrylic acid; Additive: 0.3 parts of polyether-modified polysiloxane; Defoamer: 0.02 parts; Dispersant: 0.01 parts.

[0026] Then, the base paper was coated on one side using a doctor blade coating method, with a coating amount of 12g / m². After step (7), the product is dried, calendered (soft calendering treatment, linear pressure 120kN / m, temperature 80℃), wound up, and packaged.

[0027] The results of the finished paper performance test are as follows: basis weight 102 g / m², K&N value 32%, paper surface gloss 72%, printing gloss 95%, surface strength 1.2 m / s, smoothness 1350 s, roughness 1.1 μm, breaking length 5800 m, and whiteness 85% ISO.

[0028] The couplet paper produced in Example 1, printed using gravure printing, has no issues with white gaps (pockmarks) in the printed flowers (e.g., Figure 2 (As shown). Additionally, when writing with a brush, the ink dries within 10 minutes.

[0029] Example 2 Make couplet paper using the following method.

[0030] Step (1) Pulp preparation: Mix bleached sulfate softwood chemical pulp (NBKP) and bleached sulfate hardwood chemical pulp (LBKP) at a ratio of 6% and 94% respectively; Step (2) Pulping: NBKP and LBKP are pulped separately. The NBKP pulping degree is controlled at 45°SR to provide good fiber bonding and paper strength; the LBKP pulping degree is controlled at 28°SR to provide excellent paper forming uniformity, smoothness and softness. Step (3) Seasoning: Add 1.5 kg / ton of oven-dried carboxymethyl modified starch (CMS) to the slurry. Step (4) Grouting, sand and air removal, and grouting: Step (5) involves fine screening, wire dewatering and forming, pressing, and pre-drying to obtain base paper with a g / m² content. Step (6) Surface coating: Mix the following components in the indicated weight ratios to obtain a coating with a solid content of 60% and a viscosity of 980 mPa·s: Pigment: 100 parts flaky kaolin; Adhesive: 0.5 parts carboxyl-modified PVA, 6 parts styrene-butadiene latex; Water-retaining agent: 0.4 parts of modified alkali-swellable acrylic acid; Additive: 0.4 parts of polyether-modified polysiloxane; Defoamer: 0.015 parts; Dispersant: 0.008 parts.

[0031] Then, the base paper is coated on one side using a doctor blade coating method, with a coating amount of 10g / m². After step (7), the product is dried, calendered (soft calendering treatment, linear pressure 100kN / m, temperature 70℃), wound up, and packaged.

[0032] The results of the finished paper performance test are as follows: basis weight 97 g / m², K&N value 30%, paper surface gloss 68%, printing gloss 92%, surface strength 1.1 m / s, smoothness 1250 s, roughness 1.2 μm, breaking length 5300 m, and whiteness 84.5% ISO.

[0033] Example 3 Make couplet paper using the following method.

[0034] Step (1) Pulp preparation: Mix bleached sulfate softwood chemical pulp (NBKP) and bleached sulfate hardwood chemical pulp (LBKP) at a ratio of 10% and 90% respectively; Step (2) Pulping: NBKP and LBKP are pulped separately. The NBKP pulping degree is controlled at 38°SR to provide good fiber bonding and paper strength; the LBKP pulping degree is controlled at 35°SR to provide excellent paper forming uniformity, smoothness and softness. Step (3) Seasoning: Add 3 kg / ton of oven-dried slurry carboxymethyl modified starch (CMS) to the slurry. Step (4) Grouting, sand and air removal, and grouting: Step (5) involves fine screening, wire dewatering and forming, pressing, and pre-drying to obtain base paper with a strength of 110 g / m². Step (6) Surface coating: Mix the following components in the indicated weight ratios to obtain a coating with a solid content of 64% and a viscosity of 1025 mPa·s: Pigment: 100 parts flaky kaolin; Adhesive: 1.2 parts carboxyl-modified PVA, 10 parts styrene-butadiene latex; Water-retaining agent: 0.5 parts of modified alkali-swellable acrylic acid; Additive: 0.2 parts of polyether-modified polysiloxane; Defoamer: 0.022 parts; 0.012 parts of dispersant.

[0035] Then, the base paper was coated on one side using a doctor blade coating method, with a coating amount of 15 g / m². After step (7), the product is dried, calendered (soft calendering treatment, linear pressure 150kN / m, temperature 90℃), wound up, and packaged.

[0036] The results of the finished paper performance test are as follows: basis weight 125 g / m², K&N value 34%, paper surface gloss 78%, printing gloss 98%, surface strength 1.5 m / s, smoothness 1500 s, roughness 0.9 μm, breaking length 6200 m, and whiteness 86% ISO.

[0037] Comparative Example 1 Commercially available ordinary coated paper has a basis weight of 97 g / m², a K&N value of 20%, a paper surface gloss of 56%, a printing gloss of 82%, a surface strength of 1.0 m / s, a smoothness of 895 s, a roughness of 1.75 μm, a breaking length of 5280 m, and a whiteness of 88.0% ISO. Figure 1 As shown, the flowers printed using gravure printing have a problem with white gaps (pockmarks) (the halftone dots in the center of the petals are missing). In addition, the ink written with a brush does not dry within 2 hours.

[0038] Comparative Example 2 Make couplet paper using the following method.

[0039] Step (1) Pulp preparation: Mix bleached sulfate softwood chemical pulp (NBKP) and bleached sulfate hardwood chemical pulp (LBKP) at a ratio of 8% and 92% respectively; Step (2) Pulping: NBKP and LBKP are pulped separately. The NBKP pulping degree is controlled at 40°SR to provide good fiber bonding and paper strength; the LBKP pulping degree is controlled at 30°SR to provide excellent paper forming uniformity, smoothness and softness. Step (3) Seasoning: Add 2 kg / ton of oven-dried slurry carboxymethyl modified starch (CMS) to the slurry. Step (4) Grouting, sand and air removal, and grouting: Step (5) involves fine screening, wire dewatering and forming, pressing, and pre-drying to obtain base paper with a weight of 90 g / m². Step (6) Surface coating: Mix the following components in the indicated weight ratios to obtain a coating with a solid content of 62% and a viscosity of 925 mPa·s: Pigment: 100 parts flaky kaolin; Adhesive: 0.8 parts carboxyl-modified PVA, 8 parts styrene-butadiene latex; Water-retaining agent: 0.3 parts of modified alkali-swellable acrylic acid; Defoamer: 0.02 parts; Dispersant: 0.01 parts.

[0040] Then, the base paper was coated on one side using a doctor blade coating method, with a coating amount of 12g / m². After step (7), the product is dried, calendered (soft calendering treatment, linear pressure 120kN / m, temperature 80℃), wound up, and packaged.

[0041] The results of the finished paper performance test are as follows: basis weight 97.5 g / m², K&N value 29.5%, paper surface gloss 72%, printing gloss 91%, surface strength 1.25 m / s, smoothness 1350 s, roughness 0.95 μm, breaking length 5380 m, and whiteness 85.5% ISO.

[0042] The couplet paper produced in Comparative Example 2, printed using gravure printing, had flowers with pitted patterns, a problem similar to Comparative Example 1. Additionally, ink written with a brush dried in 8 minutes.

[0043] As can be seen from the data in Example 1 and Comparative Example 1, polyether-modified polysiloxane is indispensable in this invention. It precisely controls the ink absorption and completely solves the problems of "watering" and slow drying when writing with ordinary red paper brushes.

[0044] Comparative Example 3 The paper for couplets should be manufactured using the following method. (Modified alkali-swellable acrylic acid is not used; starch is used as a water-retaining agent.) Step (1) Pulp preparation: Mix bleached sulfate softwood chemical pulp (NBKP) and bleached sulfate hardwood chemical pulp (LBKP) at a ratio of 10% and 90% respectively; Step (2) Pulping: NBKP and LBKP are pulped separately. The NBKP pulping degree is controlled at 38°SR to provide good fiber bonding and paper strength; the LBKP pulping degree is controlled at 35°SR to provide excellent paper forming uniformity, smoothness and softness. Step (3) Seasoning: Add 3 kg / ton of oven-dried slurry carboxymethyl modified starch (CMS) to the slurry. Step (4) Grouting, sand and air removal, and grouting: Step (5) involves fine screening, wire dewatering and forming, pressing, and pre-drying to obtain base paper with a strength of 110 g / m². Step (6) Surface coating: Mix the following components in the indicated weight ratios to obtain a coating with a solid content of 64% and a viscosity of 1025 mPa·s: Pigment: 100 parts flaky kaolin; Adhesive: 1.2 parts carboxyl-modified PVA, 10 parts styrene-butadiene latex; Water-retaining agent: 3 parts starch; Additive: 0.2 parts of polyether-modified polysiloxane; Defoamer: 0.022 parts; 0.012 parts of dispersant.

[0045] Then, the base paper was coated on one side using a doctor blade coating method, with a coating amount of 15 g / m². After step (7), the product is dried, calendered (soft calendering treatment, linear pressure 150kN / m, temperature 90℃), wound up, and packaged.

[0046] The results of the finished paper performance test are as follows: basis weight 97.5 g / m², K&N value 29.8%, paper surface gloss 65%, printing gloss 85%, surface strength 1.3 m / s, smoothness 1150 s, roughness 1.32 μm, breaking length 5130 m, and whiteness 85.6% ISO.

[0047] The above methods, which do not use modified alkali-swellable acrylic acid and instead use starch as a water-retaining agent, result in lower gloss, smoothness, and roughness. In gravure printing, the print quality is insufficient.

[0048] Viscosity tests were conducted on the coatings of Example 3 and Comparative Example 3, according to GB / T1723-1993. The results are listed in the table below.

[0049]

[0050] Unlike the traditional coating water-retaining agent used in Comparative Example 3, which uses starch, this invention uses modified alkali-swellable acrylic acid as a water-retaining agent. When starch is used as a water-retaining agent, the coating is greatly affected by temperature (as shown in the table above), resulting in unstable coating uniformity and unstable coating opacity, which seriously affects the printing effect. Using modified alkali-swellable acrylic acid as a water-retaining agent can avoid this problem.

[0051] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing paper suitable for gravure printing and calligraphy couplets, characterized in that, Includes the following steps: Step (1) Pulp preparation: Mix bleached sulfate softwood chemical pulp and bleached sulfate hardwood chemical pulp at a ratio of 5-10% and 90-95% respectively; Step (2) beating: NBKP beating degree is controlled at 38-48°SR to provide good fiber bonding and paper strength; LBKP beating degree is controlled at 25-35°SR to provide excellent paper forming uniformity, smoothness and softness; Step (3) Seasoning: Add carboxymethyl modified starch to the slurry; Step (4) Grouting, sand and air removal, and grouting: Step (5) Fine screening, wire section dewatering and forming, pressing, and pre-drying are used to obtain the base paper: Step (6) Surface coating: Mix the following components in the indicated weight ratios to obtain the coating: Pigment: 100 parts flaky kaolin Adhesive: 0.5-1.2 parts carboxyl-modified PVA, 6-10 parts styrene-butadiene latex Water-retaining agent: 0.3-0.5 parts of modified alkali-swellable acrylic acid. Additive: 0.2-0.4 parts of polyether-modified polysiloxane Dispersant: 0.015-0.022 parts; Defoamer: 0.008-0.012 parts; Then, the base paper is coated on one side using a doctor blade coating method; After step (7), the product is dried, calendered, rolled up, and packaged.

2. The preparation method of paper suitable for gravure printing and calligraphy writing as described in claim 1, characterized in that: The carboxymethyl modified starch is a white or light yellow powder with a degree of substitution (DS) of 0.4-0.6, a solid content of ≥90%, a viscosity of 800-1500 mPa·s in a 2% aqueous solution at 25°C, and a pH of 8.0-10.0 in a 1% aqueous solution.

3. The preparation method of paper suitable for gravure printing and calligraphy writing as described in claim 1, characterized in that: In step (3), the amount of carboxymethyl modified starch added is 1-3 kg / ton of slurry.

4. The preparation method according to claim 1, characterized in that... The raw material components of the coating include: Pigment: 100 parts flaky kaolin; Adhesive: 0.8 parts carboxyl-modified PVA, 8 parts styrene-butadiene latex; Water-retaining agent: 0.3 parts of modified alkali-swellable acrylic acid; Additive: 0.3 parts of polyether-modified polysiloxane; Dispersant: 0.02 parts; Defoamer: 0.01 parts.

5. The preparation method of paper suitable for gravure printing and calligraphy writing as described in claim 1, characterized in that: In step (6), the coating amount is 10-15 g / m².

6. The preparation method of paper suitable for gravure printing and calligraphy writing as described in claim 1, characterized in that: The carboxyl-modified PVA is a white powder with a solid content ≥90%, a degree of alcoholysis of 93-95 mol%, a viscosity of 25-35 mPa·s in a 4% aqueous solution at 20℃, and a pH value of 5.0-7.0 in a 4% aqueous solution.

7. The method for preparing paper suitable for gravure printing and calligraphy writing as described in claim 1, characterized in that: The styrene-butadiene latex is a white emulsion with a solid content of 48-52%, a Brookfield viscosity of <300 mPa·s at 25℃ and 60 rpm, a pH value of 7.0-9.0, and a bound styrene content of 60-70%.

8. The method for preparing paper suitable for gravure printing and calligraphy writing as described in claim 1, characterized in that: The modified alkali-swellable acrylic acid is a milky white emulsion with a solid content of 28-32% and a pH value of 2.5-4.

5.

9. The method for preparing paper suitable for gravure printing and calligraphy writing as described in claim 1, characterized in that: The polyether-modified polysiloxane is a transparent to semi-transparent liquid with an effective ingredient content of 100%, a viscosity of 500-1500 mPa·s at 25°C, and a pH value of approximately neutral 6.0-8.

0.

10. The method for preparing paper suitable for gravure printing and calligraphy writing as described in claim 1, characterized in that: The specific calendering process parameters are: soft calendering, linear pressure of 100-150 kN / m, temperature of 70-90℃, preferably linear pressure of 120 kN / m, temperature of 80℃.

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