High-smoothness electrostatic copy paper and preparation method thereof

Abstract

The present invention provides high-smoothness electrostatic copy paper and a preparation method thereof. The raw materials include a base paper layer pulp and a sizing layer pulp. The base paper layer pulp includes kraft hardwood pulp, kraft softwood pulp, mechanical pulp, filler, and alkenyl succinic anhydride. The sizing layer pulp includes starch, a surface sizing agent, and a metal salt. By selecting appropriate refining freeness and pulp formulation, the present invention achieves good bulk while controlling water absorption. By adjusting the type and amount of different fillers, combined with process moisture control and optimization of overpressure conditions, the dimensional stability and smoothness of the paper are improved, resulting in a product with a good feel and good machine performance.

Description

Technical Field

[0001] The invention relates to the technical field of papermaking, in particular to a method for preparing high-smoothness electrostatic copy paper. Background Art

[0002] Ordinary copy paper contains a lot of ash. During the printing or copying process, due to the static electricity between the papers, the papers stick together, which can easily cause paper jams and increase the failure rate of printing and copying equipment. Therefore, it is necessary to eliminate the static electricity between the copy papers, improve printing efficiency, and reduce paper jams.

[0003] Electrostatic copy paper is a specialized paper used in electrostatic copiers for copying documents and materials. It can also be used in inkjet and laser printers, making it a common printing and copying paper on the market. The performance of electrostatic copy paper is primarily determined by two aspects: first, good machine handling, typically requiring smooth passage through equipment with copy speeds of 100 sheets per minute or higher without jamming. Second, good flatness ensures that the printed paper remains flat and free of warping. Summary of the Invention

[0004] In view of this, the present invention proposes a method for preparing high-smoothness electrostatic copy paper to solve the above problems.

[0005] The technical solution of the present invention is achieved as follows:

[0006] Disclosed is a high-smoothness electrostatic copy paper, the raw materials of which include base paper layer pulp and sizing layer pulp. The base paper layer pulp includes sulfate hardwood pulp, sulfate softwood pulp, mechanical pulp, filler and alkenyl succinic anhydride, and the raw materials of the sizing layer pulp include starch, surface sizing agent and metal salt.

[0007] Furthermore, the base paper layer pulp includes 50 to 90 parts of sulfate broadleaf pulp, 5 to 30 parts of sulfate coniferous pulp, and 10 to 30 parts of mechanical pulp by weight. The amount of filler added is 10-30% of the total mass of chemically bleached sulfate broadleaf pulp, sulfate coniferous pulp, and mechanical pulp, and the amount of alkenyl succinic anhydride used is 0.5 to 2.5 kg / ton.

[0008] Furthermore, the starch is one of oxidized starch and enzyme-converted starch, the sizing agent is one of styrene-acrylate anionic sizing agent, styrene-acrylate anionic sizing agent and alkyl ketene dimer composite anionic surface sizing agent, and the mass ratio of sizing agent, metal salt and starch is 0.005-0.015:0.01-5:1.

[0009] Furthermore, the metal salt is sodium sulfate.

[0010] Furthermore, the preparation method of the enzyme-converted starch is as follows: starch and warm water are mixed to prepare a starch solution with a mass concentration of 25% to 35%, 100 to 300 ppm of medium-temperature α-amylase is added, the pH value of the starch solution is adjusted to 6-8 using a sodium hydroxide solution, the reaction is carried out for 30-60 minutes, and after the reaction is completed, 120-150°C steam is introduced for gelatinization and inactivation to obtain the enzyme-converted starch.

[0011] Furthermore, the starch is one of cassava starch, corn starch, sweet potato starch and potato starch.

[0012] Furthermore, the filler is one or a combination of two or more of titanium dioxide, precipitated calcium carbonate, ground calcium carbonate, and porcelain clay.

[0013] Furthermore, the preparation method of the high-smoothness electrostatic copy paper comprises the following steps:

[0014] (1) Sulfate hardwood pulp, sulfate softwood pulp and mechanical pulp are mixed separately, fillers, alkenyl succinic anhydride, cationic starch and retention and drainage aids are added in sequence to prepare slurry, the slurry is formed on a screen, vacuum dewatered, and hard calendered with a line pressure of ≥30 kN / m to prepare base paper with a moisture content of ≤5%;

[0015] (2) applying sizing to the surface of the sizing layer slurry by film transfer to obtain sized paper;

[0016] (3) The sized paper is super-calendered to obtain the finished product.

[0017] Furthermore, in step (1), the freeness of sulfated broadleaf pulp is ≥380 ml, the freeness of sulfated coniferous pulp is ≥380 ml, and the freeness of mechanical pulp is ≥250 ml.

[0018] Furthermore, in step (1), the amount of cationic starch used is 0.1-10 kg / t, the amount of cationic polyacrylamide added is 0.1-200 ppm, the amount of silica sol added is 0.0-8.0 kg / t, and the amount of anionic polyacrylamide used is 0.1-200 ppm.

[0019] Furthermore, in step (1), the glue application amount on one side is 0.5-1.5 gsm.

[0020] Furthermore, in step (2), the base paper after sizing is dried by infrared and hot air to control the moisture content to be ≤5%. Furthermore, the super calendering adopts a 2nip mode, a calendering temperature ≥50°C, and a calendering pressure ≥20KN / m.

[0021] Furthermore, the production process controls the moisture content before sizing to be ≤5% and the moisture content during coiling to be ≤5%.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention achieves good bulk and controls water absorption by selecting appropriate pulping freeness and pulp formulation. By adjusting the types and amounts of different fillers, combined with process moisture control and optimization of overpressure conditions, the dimensional stability and smoothness of the paper are improved, giving the product a good feel and machine performance. By adding and coating different types of sizing agents internally and externally, the cobb value is controlled at a low level, ensuring good paper quality and no warping after printing. It has been verified that the paper produced by the present invention can pass through the fastest domestic copying equipment with a speed of 125 sheets / min without paper jams, reaching the domestic advanced level. DETAILED DESCRIPTION

[0024] In order to better understand the technical content of the present invention, specific examples are provided below to further illustrate the present invention.

[0025] Unless otherwise specified, the experimental methods used in the examples of the present invention are all conventional methods.

[0026] Unless otherwise specified, the materials, reagents, etc. used in the examples of the present invention can be obtained from commercial sources.

[0027] The starch used in the present invention is enzyme-cut starch made from cassava starch. Cassava starch and warm water were mixed to prepare a 30% starch solution. 200 ppm of moderate-temperature α-amylase was added, and the pH of the starch solution was adjusted to 7 using sodium hydroxide solution. The solution was reacted for 50 minutes. After the reaction, the solution was steamed at 130°C for gelatinization and inactivation to produce enzyme-converted starch.

[0028] Example 1 Preparation method of high-smoothness electrostatic copy paper

[0029] (1) Sulfate hardwood pulp, sulfate softwood pulp and mechanical pulp are mixed separately, and precipitated calcium carbonate, cationic starch, alkenyl succinic anhydride and retention and drainage aids are added in sequence to prepare a slurry, the slurry is placed on a screen for forming, and vacuum dehydration is performed to prepare base paper;

[0030] (2) applying sizing to the surface of the sizing layer by film transfer, with a single-side sizing amount of 0.7 gsm, and rolling up the paper with a moisture content of 4.5% after drying;

[0031] (3) Super calendering was performed in 2nip mode, with a calendering temperature of 180°C and a calendering line pressure of 30 kN / m to obtain the finished product.

[0032] Comparative Example 1 Preparation Method of High Smoothness Electrostatic Copy Paper

[0033] The amount of raw materials was adjusted based on Example 1.

[0034] Comparative Example 2 Preparation Method of High Smoothness Electrostatic Copy Paper

[0035] Based on Example 1, the order of adding the components in step (1|) was adjusted. Specifically:

[0036] (1) Sulfate broadleaf pulp, sulfate coniferous pulp and mechanical pulp are mixed separately, and cationic starch, precipitated calcium carbonate, alkenyl succinic anhydride and retention and drainage aids are added in sequence to prepare slurry, which is formed on a screen and vacuum dehydrated to obtain base paper.

[0037]

[0038]

[0039] Test Example 1

[0040] The copy papers prepared in Example 1 and Comparative Examples 1-2 were tested.

[0041]

[0042] Experimental results show that the high-smoothness electrostatic copy paper of the present invention achieves excellent bulk and water absorption by rationally compounding sulfated hardwood pulp, sulfated softwood pulp, and mechanical pulp, adjusting the order of adding cationic starch, precipitated calcium carbonate, alkenyl succinic anhydride, and retention and drainage aids, and controlling the moisture content during the papermaking process. Optimizing overpressure conditions based on the pulp composition enhances the paper's dimensional stability and smoothness, resulting in a product with a good feel and excellent machine performance.

[0043] The sizing agent in the present invention is composed of starch, surface sizing agent and metal salt. Different types of sizing agents are added internally and applied externally to control the cobb value at a low level, ensuring that the paper is in good condition and has no warping after printing.

[0044] In Comparative Example 1 of the present invention, the paper's copying performance was reduced by adjusting the slurry ratio. In Comparative Example 2, the paper's performance was reduced by adjusting the order of adding cationic starch, precipitated calcium carbonate, alkenyl succinic anhydride, and retention and drainage aid.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-smoothness electrostatic copy paper, characterized in that: The raw materials include base paper layer pulp and sizing layer pulp, wherein the base paper layer pulp includes 50-90 parts by weight of kraft hardwood pulp, 5-30 parts by weight of kraft softwood pulp, 10-30 parts by weight of mechanical pulp, filler, alkenyl succinic anhydride, cationic starch and retention and drainage aids; The amount of filler added is 10-30% of the total mass of chemically bleached kraft hardwood pulp, kraft softwood pulp and mechanical pulp; The amount of alkenyl succinic anhydride used is 0.5-2.5 kg / ton; the amount of cationic starch used is 8 kg / ton; the amount of retention and drainage aids used is 120 ppm of cationic polyacrylamide and 120 ppm of anionic polyacrylamide; The sizing layer slurry raw materials include starch, surface sizing agent and metal salt; The starch in the sizing layer slurry raw material is one of oxidized starch and enzyme-converted starch; The surface sizing agent is one of a styrene-acrylate anionic sizing agent and an anionic surface sizing agent compounded with a styrene-acrylate anionic sizing agent and an alkyl ketene dimer; The method for preparing the high-smoothness electrostatic copy paper comprises the following steps: (1) Sulfate hardwood pulp, sulfate softwood pulp and mechanical pulp are mixed separately, filler, cationic starch, alkenyl succinic anhydride and retention and drainage aid are added in sequence to prepare slurry, the slurry is put on a screen for forming, and vacuum dehydration is performed to prepare base paper; (2) applying sizing to the surface of the sizing layer slurry by film transfer to obtain sized paper; (3) Calendering the sized paper to obtain the finished product; In step (1), the freeness of the sulfated hardwood pulp is ≥380 ml, the freeness of the sulfated softwood pulp is ≥380 ml, and the freeness of the mechanical pulp is ≥250 ml; In step (3), the calendering is performed using a 2nip mode for super calendering, with a calendering temperature ≥ 50°C and a calendering pressure ≥ 20KN / m.

2. The high-smoothness electrostatic copy paper according to claim 1, characterized in that: The preparation method of the enzyme-converted starch comprises the following steps: mixing starch and warm water to prepare a starch solution with a mass concentration of 25% to 35%, adding 100 to 300 ppm of medium-temperature α-amylase, adjusting the pH value of the starch solution to 6 to 8 using a sodium hydroxide solution, reacting for 30 to 60 minutes, and then introducing steam at 120 to 150° C. for gelatinization and inactivation to obtain the enzyme-converted starch.

3. The high-smoothness electrostatic copy paper according to claim 2, characterized in that: The starch is one of cassava starch, corn starch, sweet potato starch and potato starch.

4. The high-smoothness electrostatic copy paper according to claim 1, characterized in that: The filler is one or a combination of two or more of titanium dioxide, precipitated calcium carbonate, ground calcium carbonate, and porcelain clay.

5. The high-smoothness electrostatic copy paper according to claim 1, characterized in that: A method for preparing high-smoothness electrostatic copy paper, wherein in step (1), the amount of glue applied on one side is 0.5-1.5 gsm.

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