Two-side offset paper and preparation method thereof

Abstract

The invention provides two-side offset paper and a preparation method thereof. The preparation method comprises the following steps: making raw paper; wherein paper pulp of the raw paper comprises chemimechanical pulp and chemical pulp, and the chemimechanical pulp is subjected to biological pretreatment; respectively carrying out surface sizing on the two surfaces of the raw paper; wherein the surface sizing agent is cross-linked modified starch. According to the preparation method of the two-side offset paper provided by the embodiment of the invention, a raw paper papermaking scheme of mechanical pulp pretreatment: chemithermomechanical pulp and chemical pulp is adopted, the proportion of the chemithermomechanical pulp is increased, and the ash content is increased, so that the purposes of saving raw materials, reducing energy consumption and optimizing the production cost are achieved; besides, the cross-linked modified starch is adopted as the surface sizing agent, so that the surface dry strength of the paper sheet can be improved, the quality and the cost of the thin and book two-side offset paper are bidirectionally optimized through the scheme, and the aims of higher quality and lower cost are achieved.

Description

Technical Field

[0001] The present application relates to the technical field of papermaking, and in particular to offset paper and a preparation method thereof. Background Art

[0002] Offset paper refers to printing paper, also called offset paper. It is one of the typical representative paper types for cultural and printing paper. In business, it is the abbreviation of double-sided offset paper (double-sided offset printing paper), formerly known as Daolin paper. Offset paper has a wide range of uses. Various books and textbooks are its first choice, followed by magazines, color pages, product catalogs, maps, calendars, calendars, covers, inserts, illustrations, product manuals, manuals, comics, cartoon books, advertising posters, corporate brochures, leaflets, envelopes, books, notebooks, dyed embossing, forms, office / official paper, business cards, color trademarks and various packaging products. The printed image of offset paper is slightly worse than that of coated paper and light coated paper, but its weight is much lighter than the latter two, which will greatly reduce the mailing cost; the production cost is also less than that of coated paper and light coated paper.

[0003] The main target groups of offset paper are students and office workers, and the demand is relatively rigid. In particular, students have a large demand for cultural paper and relatively low requirements for product quality. The industry has a low entry threshold, and there are many companies, mainly small and medium-sized enterprises. The main uses of offset paper for notebooks are as follows. Student notebooks: It is one of the most commonly used papers in students' daily study, used to make homework books (such as Chinese homework books, mathematics homework books, etc.), notebooks (class notes, learning experience, etc.), draft books, etc. Office notebooks: It is also widely used in office scenes, such as meeting record books, work log books, note books, etc., which are convenient for people to record important information, arrangements and plans at work. Other uses: It can also be used to make some special-purpose notebooks, such as drawing books (suitable for sketches, quick sketches, watercolors and other painting forms), handbooks (used to record daily life, hobbies, travel experiences, etc.), etc.

[0004] At present, the main defects of offset paper for notebooks are as follows: (1) The smoothness of the paper surface is low and the fineness is poor. When writing on the paper with writing tools such as fountain pens and ballpoint pens, the paper may jam or hang, affecting the writing speed and writing quality; (2) The surface strength is poor and cannot reach the strength of 14# wax stick. During the printing process, the ink will cause the fibers or fillers on the surface of the paper to fall off, resulting in powder and hair loss. When writing, the pen tip may also bring up the paper fibers, making the paper surface rough or damaged; (3) The sizing degree is low. After the ink spreads on the paper, the handwriting becomes blurred and difficult to recognize; (4) The opacity is low, and there is print-through when printing or writing; (5) The amount of high-yield mechanical pulp used is relatively small, and the proportion of chemical pulp is relatively high, which does not conform to the concept of green and environmentally friendly papermaking. Summary of the invention

[0005] A first aspect of an embodiment of the present application provides a method for preparing offset paper, the method comprising:

[0006] Papermaking base paper; wherein the pulp of the base paper comprises chemical mechanical pulp and chemical pulp, and the chemical mechanical pulp is subjected to biological pretreatment;

[0007] Surface sizing is performed on both sides of the base paper respectively; wherein the surface sizing agent is cross-linked modified starch.

[0008] In some embodiments, the cross-linked modified starch includes any one of enzyme-modified starch, oxidized starch, and cationic surface sizing starch.

[0009] In some embodiments, the amount of the surface sizing agent on both sides of the base paper is 1.0-2.0 g / m 2 .

[0010] In some embodiments, the surface sizing agent further comprises a surface enhancing agent, and the surface enhancing agent comprises any one of modified cross-linked polyvinyl alcohol, modified carboxymethyl cellulose, and modified guar gum.

[0011] In some embodiments, the chemical pulp includes coniferous chemical pulp and hardwood chemical pulp, and the ratio of chemical mechanical pulp: coniferous chemical pulp: hardwood chemical pulp is (20-30):(20-30):(40-60).

[0012] In some embodiments, the pulp further includes a filler; the mass ratio of the filler to the pulp is (20-25):(80-75); the filler includes a mixture of any one or more of light calcium carbonate, heavy calcium carbonate, talc, and titanium dioxide.

[0013] In some embodiments, the pulp further comprises a chemical additive, wherein the chemical additive comprises a mixture of any one or more of a dye, a dry strength agent, an internal sizing agent, and a binary or ternary retention / drainage aid.

[0014] In some embodiments, the paper pulp further includes an internal sizing agent, and the internal sizing agent includes any one of alkyl ketene dimer and alkenyl succinate glycoside or a mixture of both.

[0015] In some embodiments, the pulp further includes cationic starch and medium- and low-molecular-weight cationic polyacrylamide, wherein the amount of the ionic starch is 0.8-1.4% of the absolute dry pulp of the pulp, and the amount of the cationic polyacrylamide is 0.8-2.0% of the absolute dry pulp of the pulp.

[0016] In a second aspect, an embodiment of the present application provides an offset paper, which is prepared by the preparation method described in the above embodiment.

[0017] The method for preparing offset paper provided in the embodiment of the present application adopts mechanical pulp pretreatment: a base paper making scheme of "chemimechanical pulp + chemical pulp" is used to increase the proportion of chemimechanical pulp and the ash content, so as to achieve the purpose of saving raw materials, reducing energy consumption and optimizing production costs; in addition, by adopting cross-linked modified starch as a surface sizing agent, the dry strength of the paper surface can be improved. Through the above scheme, the quality and cost of the book offset paper are optimized in a two-way manner, achieving the goal of higher quality and lower cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 It is a schematic flow chart of an embodiment of a method for preparing offset paper of the present application;

[0020] Figure 2 It is a schematic diagram of the stacking structure of an embodiment of the offset paper of the present application. DETAILED DESCRIPTION

[0021] The present application is further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present application, but are not intended to limit the scope of the present application. Similarly, the following examples are only some embodiments of the present application rather than all embodiments, and all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0022] The terms "first", "second", and "third" in the embodiments of the present application are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first", "second", and "third" can expressly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the embodiments of the present application, all directional indications (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. The terms "including" and "having" in the embodiments of the present application and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or components inherent to these processes, methods, products, or devices.

[0023] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] See also Figure 1 , Figure 1 1 is a flow chart of an embodiment of a method for preparing offset paper of the present application. The preparation method in this embodiment includes but is not limited to the following steps.

[0025] Step S100, papermaking base paper; wherein the pulp of the base paper includes chemical mechanical pulp and chemical pulp, and the chemical mechanical pulp is subjected to biological pretreatment.

[0026] In this step, the pulp of the base paper includes chemical mechanical pulp, chemical pulp, filler, chemical additives and internal sizing agent. Among them, chemical mechanical pulp includes BCTMP-bleached thermo-grinded chemical mechanical pulp, APMP-alkaline hydrogen peroxide bleached mechanical pulp, CTMP-thermo-grinded chemical mechanical pulp, etc.; the chemical mechanical pulp in this embodiment is biologically pretreated by xylanase, cellulase, laccase, etc. Through biological pretreatment technology, the lignin in the chemical mechanical pulp is degraded, the molar mass of the residual lignin is reduced, the phenolic hydroxyl group in the lignin is reduced, and the carboxyl group is increased, thereby improving the strength of the pulp. In order to ensure the thickness of the offset paper, a large amount of mechanical pulp needs to be added, but due to the high content of chemical mechanical pulp fiber bundles, the use of a large amount of chemical mechanical pulp will cause the smoothness of the paper surface to become lower (high roughness), the printing adaptability and printing fineness to become worse; it will also cause the surface strength of the paper to become lower, resulting in problems such as printing powder loss. Therefore, the chemical-mechanical pulp must be pretreated first to soften the lignin in the chemical-mechanical pulp, so as to reduce the fiber bundles of the chemical-mechanical pulp and maintain the bulk of the chemical-mechanical pulp while maintaining a low refining energy consumption.

[0027] Optionally, the chemical pulp includes coniferous chemical pulp and hardwood chemical pulp, and the weight percentage of chemical mechanical pulp: coniferous chemical pulp: hardwood chemical pulp is (20-30): (20-30): (40-60). Among them, when the chemical mechanical pulp ratio is 20-30%, the pulping freeness is controlled at 200-250ml; when the coniferous chemical pulp ratio is controlled at 20-30%, the pulping freeness is controlled at 300-350ml; when the hardwood chemical pulp ratio is 40-60%, the freeness is controlled at 300-330ml. The use of a higher mechanical pulp ratio is to ensure that the paper still has a higher bulk when a high filler ratio is used later.

[0028] The mass ratio of filler to pulp is (20-25): (80-75); the filler includes a mixture of any one or more of light calcium carbonate, heavy calcium carbonate, talcum powder, and titanium dioxide. The filler ratio is controlled at 20-30% (adjusted according to the actual gram weight), and one or a mixture of PCC, GCC, talcum powder, and titanium dioxide is used as the filler, and a higher proportion is used. While improving the opacity of the paper, it ensures that the paper type has a good paper surface microstructure, which has a positive effect on smoothness and ink absorption. Chemical additives include a mixture of any one or more of dyes, dry strength agents, internal sizing agents, binary or ternary retention / drainage aids (including cationic polyacrylamide + micro-silica sol / bentonite + anionic polyacrylamide). The dye uses a yellow dye, and a red dye is added to the color scheme to make the paper reach the required color.

[0029] Optionally, in the preparation method of this embodiment, the pulp uses cationic starch and medium and low molecular weight cationic polyacrylamide as strengthening agents, and the amount of cationic starch used as a strengthening agent is 0.8-1.4% (for absolute dry pulp); the amount of cationic polyacrylamide used as a strengthening agent is 0.8-2.0% (for absolute dry pulp).

[0030] Optionally, the paper pulp further includes an internal sizing agent, which includes any one of alkyl ketene dimer (AKD) and alkenyl succinate glycoside (ASA) with different carbon ratios or a mixture of the two. The amount of alkyl ketene dimer (AKD) is 8-15 kg / ton of base paper, the amount of alkenyl succinate glycoside (ASA) is 0.8-2.0 kg / ton of base paper, or the two are combined for sizing.

[0031] Please continue reading Figure 1 The method for preparing offset paper in this embodiment further includes step S200 of applying surface sizing to both sides of the base paper; wherein the surface sizing agent is cross-linked modified starch.

[0032] In step S200, the cross-linked modified starch includes any one of enzyme-modified starch, oxidized starch and cationic surface sizing starch. The amount of surface sizing agent used on both sides of the base paper is 1.0-2.0 g / m 2 , specifically 1.0g / m 2 , 1.2g / m 2 1.25g / m 2 , 1.3g / m 2 , 1.5g / m 2 , 1.8g / m 2 , 2.0g / m 2 Equal values.

[0033] In addition, the surface sizing agent in this embodiment also includes a surface enhancer, which includes any one of modified cross-linked polyvinyl alcohol, modified carboxymethyl cellulose, and modified guar gum. The surface enhancer works together with the cross-linked modified starch to improve the dry strength of the paper surface.

[0034] The method for preparing offset paper provided in the embodiment of the present application adopts mechanical pulp pretreatment: a base paper making scheme of "chemimechanical pulp + chemical pulp" is used to increase the proportion of chemimechanical pulp and the ash content, so as to achieve the purpose of saving raw materials, reducing energy consumption and optimizing production costs; in addition, by adopting cross-linked modified starch as a surface sizing agent, the dry strength of the paper surface can be improved. Through the above scheme, the quality and cost of the book offset paper are optimized in a two-way manner, achieving the goal of higher quality and lower cost.

[0035] Several specific embodiments are described below.

[0036] Blank control group 1

[0037] Base paper making, using APMP (hydrogen peroxide bleached mechanical pulp): NBKP (coniferous wood chemical pulp): LBKP (hardwood chemical pulp) = 20%: 20%: 60% to prepare mixed pulp, adding 25% (relative to the weight of the pulp) of light calcium carbonate as filler, and then adding chemical additives, cationic starch 0.95%, AKD sizing agent 0.8%, cationic polyacrylamide retention aid 400ppm, silica gel anion retention aid 9000ppm, anionic polyacrylamide 450ppm, after papermaking and forming, and then through pressing and drying, to prepare 63g / m 2 Base paper; then surface sizing 1.0g / m 2 / surface (ordinary surface starch), prepared into 70g / m 2 The finished paper is lightly pressed by a soft calender at 30℃ / 25KN.m to obtain the product.

[0038] Example 1

[0039] Base paper making, using APMP (biological pre-treated alkaline hydrogen peroxide bleached mechanical pulp): NBKP (softwood chemical pulp): LBKP (hardwood chemical pulp) = 23%: 20%: 57% to prepare mixed pulp, adding 27% (relative to the weight of the pulp) of a mixture of light calcium carbonate + heavy calcium carbonate + talcum powder as a filler, and then adding chemical additives, charge control agent PAC 250ppm, cationic starch 0.95%, high carbon AKD sizing agent 0.8%, cationic polyacrylamide retention aid 450ppm, silica gel anion retention aid 9200ppm, anionic polyacrylamide 450ppm, after papermaking and forming, and then through pressing and drying, to prepare 63g / m 2 Base paper; then surface sizing 1.0g / m 2 / noodle (new cross-linked modified starch), prepared into 70g / m 2 The finished paper is lightly pressed by a soft calender at 30℃ / 25KN.m to obtain the product.

[0040] Example 2

[0041] Base paper making, APMP (biological pre-treated alkaline hydrogen peroxide bleached mechanical pulp): NBKP (softwood chemical pulp): LBKP (hardwood chemical pulp) = 25%: 20%: 55% to prepare mixed pulp, add 28% (relative to the weight of the pulp) of a mixture of light calcium carbonate + heavy calcium carbonate + talcum powder as a filler, and then add chemical additives, charge control agent PAC 280ppm, cationic starch 0.95%, high carbon AKD sizing agent 1.0%, cationic polyacrylamide retention aid 480ppm, silica gel anion retention aid 9400ppm, anionic polyacrylamide 480ppm, after papermaking and forming, and then through pressing and drying, to prepare 63g / m 2 Base paper; then surface sizing 2.0g / m 2 / noodle (new cross-linked modified starch), prepared into 70g / m 2 The finished paper is lightly pressed by a soft calender at 30℃ / 25KN.m to obtain the product.

[0042] Example 3

[0043] Base paper making, APMP (biological pre-treated alkaline hydrogen peroxide bleached mechanical pulp): NBKP (softwood chemical pulp): LBKP (hardwood chemical pulp) = 28%: 20%: 52% to prepare mixed pulp, 30% (relative to the weight of the pulp) of a mixture of light calcium carbonate + heavy calcium carbonate + talcum powder is added as a filler, and then chemical additives are added, charge control agent PAC 300ppm, cationic starch 0.95%, high carbon AKD sizing agent 1.2%, cationic polyacrylamide retention aid 500ppm, silica gel anion retention aid 9600ppm, anionic polyacrylamide 500ppm, after papermaking and forming, and then pressed and dried to prepare 63g / m 2 Base paper; then surface sizing 2.0g / m 2 / surface, (new cross-linked modified starch), prepared into 70g / m 2 The finished paper is lightly pressed by a soft calender at 30℃ / 25KN.m to obtain the product.

[0044] Specific experimental comparison parameters are shown in the table below.

[0045]

[0046] Through the above comparison, it can be seen that the preparation method in the embodiment of the present application improves and enhances the printing quality of the book offset paper, and to a certain extent takes into account the copying cost. Under the condition of ensuring the quality, more mechanical pulp is used, and a higher internal filler solution is adopted. The preparation method in the embodiment itself adopts the scheme of (high proportion mechanical pulp after biological pretreatment + chemical pulp + high ash content + new modified surface starch) to increase the proportion of chemical mechanical pulp and increase the ash content, so as to achieve the purpose of saving raw materials, reducing energy consumption, and optimizing production costs; in addition, by using cross-linked modified starch as a surface sizing agent, the dry strength of the paper surface can be improved. Through the above scheme, the quality and cost of the book offset paper are optimized in both directions, achieving the goal of higher quality and lower cost.

[0047] In addition, the present application also provides a double-sided paper, please refer to Figure 2 , Figure 2 1 is a schematic diagram of the stacked structure of an embodiment of the offset paper of the present application, wherein the offset paper comprises a base paper 110 and surface sizing layers 120 arranged on both sides of the base paper, wherein the materials and preparation methods of each layer of the offset paper refer to the relevant description of the aforementioned embodiment and will not be repeated here.

[0048] The advantages of the offset paper in the embodiment of the present application include: 1. The paper surface is fine and smooth; 2. The surface strength & wet pulling strength is good, the surface strength is 16# wax stick strength, and the printing does not fuzz or powder (offset printing uses the principle that oil and water do not mix. Before printing, a wetting liquid is first applied to the printing plate to form a hydrophilic film on the blank part of the printing plate, and then ink is applied to the printing plate to form an oleophilic film on the image part of the printing plate. During printing, the image part is ink-loving and water-repellent, and the blank part is hydrophilic and ink-repellent. After the rubber cloth on the elastic rubber cylinder is transferred, the image on the printing plate leaves a soft and colorful imprint on the printing material, thereby completing the printing. Because the paper is The area moistened by the fountain solution has poor surface resistance to wet picking, which can easily cause powder and block falling in the subsequent printing process in a multi-color printing process. The method in this embodiment uses the RI wet strength test method to evaluate the wet picking resistance of paper. When this test method simulates offset printing, fountain solution is applied to the surface of the paper in advance, and then black ink (Toyo 15#) is used for printing and transfer peeling to evaluate the possible hair loss and powder loss on the paper surface during the printing process, and a standard control plate is made for scoring and rating to determine the wet picking resistance of the paper); 3. The paper surface has a high degree of sizing; 4. The opacity is high, and the opacity of the paper reaches more than 87%, which solves the problem of writing show-through.

[0049] The above descriptions are only some embodiments of the present application, and do not limit the protection scope of the present application. Any equivalent device or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing offset paper, characterized in that: The preparation method comprises: Papermaking base paper; wherein the pulp of the base paper comprises chemical mechanical pulp and chemical pulp, and the chemical mechanical pulp is subjected to biological pretreatment; Surface sizing is performed on both sides of the base paper respectively; wherein the surface sizing agent is cross-linked modified starch.

2. The preparation method according to claim 1, characterized in that: The cross-linked modified starch includes any one of enzyme-modified starch, oxidized starch and cationic surface sizing starch.

3. The preparation method according to claim 2, characterized in that: The amount of the surface sizing agent on both sides of the base paper is 1.0-2.0 g / m 2 .

4. The preparation method according to claim 3, characterized in that: The surface sizing agent also includes a surface enhancer, and the surface enhancer includes any one of modified cross-linked polyvinyl alcohol, modified carboxymethyl cellulose, and modified guar gum.

5. The preparation method according to claim 1, characterized in that: The chemical pulp includes coniferous wood chemical pulp and hardwood chemical pulp, and the chemical mechanical pulp: coniferous wood chemical pulp: hardwood chemical pulp is (20-30): (20-30): (40-60).

6. The preparation method according to claim 5, characterized in that: The pulp also includes filler; the mass ratio of filler to pulp is (20-25):(80-75); the filler includes a mixture of any one or more of light calcium carbonate, heavy calcium carbonate, talcum powder, and titanium dioxide.

7. The preparation method according to claim 6, characterized in that: The pulp further comprises chemical additives, which include any one or more mixtures of dyes, dry strength agents, internal sizing agents, and binary or ternary retention / drainage aids.

8. The preparation method according to claim 7, characterized in that: The paper pulp further comprises an internal sizing agent, and the internal sizing agent comprises any one of alkyl ketene dimer and alkenyl succinate glycoside or a mixture of the two.

9. The preparation method according to claim 8, characterized in that: The paper pulp further comprises cationic starch and cationic polyacrylamide with medium and low molecular weight, wherein the amount of the ionic starch is 0.8-1.4% of the absolute dry pulp of the paper pulp, and the amount of the cationic polyacrylamide is 0.8-2.0% of the absolute dry pulp of the paper pulp.

10. A double offset paper, characterized in that: The offset paper is prepared by the preparation method according to any one of claims 1 to 9.

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