High-speed box forming paperboard and preparation method thereof

Abstract

The invention provides a high-speed box forming paperboard and a preparation method thereof. The preparation method comprises the following steps: making base paper with pulp; wherein the base paper comprises a core layer, a surface layer and a bottom layer, and paper pulp of the core layer comprises 30%-50% of BCTMP, 5%-10% of NBKP, 20%-40% of LBKP and 15%-30% of broken paper; coating the front surface of the surface layer; and carrying out back coating on the bottom layer. According to the preparation method of the high-speed boxing paperboard provided by the embodiment of the invention, the paperboard obtained by improving paper pulp ingredients can meet high-speed packaging machine operation (the packaging speed is greater than or equal to 300 boxes / min), and in addition, the paperboard has good ink absorbency, low paper lint and paper powder, excellent various coding effects, good boxing performance and good cold and hot glue while meeting high folding and explosion resistance and ink explosion resistance; and good trafficability and exquisite appearance can be achieved in the subsequent processing process.

Description

Technical Field

[0001] The present application relates to the technical field of papermaking, and in particular to a high-speed box-forming paperboard and a preparation method thereof. Background Art

[0002] At present, with the development of equipment technology, the processing speed of medicine boxes is getting faster and faster, from the original manual box folding to fully automatic packaging equipment. The packaging speed of ordinary fully automatic medicine packaging machines is about 40-100 boxes per minute, and the speed of high-speed fully automatic cartoning machines can reach 120-200 boxes per minute or even higher. In order to meet the operation performance, boxing effect and low defective rate of high-speed packaging equipment, the white cardboard for medicine packaging must have good boxing shape, anti-burst, anti-burst ink, low paper hair and paper powder and other requirements.

[0003] At present, although the common white cardboard for medicine packaging has good anti-burst performance by increasing the surface layer, bottom layer quantitative or long fiber pulp (NBKP) content or beating the fiber to improve strength, in order to achieve the same bulk, the amount of mechanical pulp is too high, resulting in more paper hair and paper powder. At the same time, it is difficult to make the strength, and it is necessary to add more starch or dry strength agent to make the paper brittle; in order to achieve good anti-burst ink performance, the proportion of coating latex is increased. However, at the same time, the cardboard will have problems such as poor coding effect and dry coding, which affects the operating efficiency of printing and packaging folding equipment. After years of white card production experience, it is found that ordinary white card for medicine packaging cannot fully meet the requirements of high-speed medicine packaging machines, especially when the packaging speed reaches more than 300 boxes / min. Summary of the invention

[0004] A first aspect of an embodiment of the present application provides a method for preparing a high-speed cartoning paperboard, the method comprising:

[0005] Papermaking base paper; wherein the base paper comprises a core layer, a surface layer and a bottom layer, and the pulp of the core layer comprises 30%-50% BCTMP, 5%-10% NBKP, 20%-40% LBKP and 15%-30% broken paper;

[0006] Performing front coating on the surface layer;

[0007] Back coating is performed on the base layer.

[0008] In some optional embodiments, the pulp of the surface layer includes 30%-40% NBKP and 60%-70% LBKP.

[0009] In some optional embodiments, the pulp of the bottom layer includes 20%-30% NBKP and 70%-80% LBKP.

[0010] In some optional embodiments, the step of performing front coating on the surface layer includes: performing three passes of scraper coating, namely primer coating, mid-coating and top coating, each coating amount is 8-100gsm, and the total coating amount is 26-30gsm.

[0011] In some optional embodiments, the amount of china clay in the coating of the middle coating and the top coating is 20-40%, the amount of calcined clay is 10-20%, and the amount of latex is 13-15%.

[0012] In some optional embodiments, in the step of back coating on the bottom layer, a layer of starch glue is applied with a coating amount of 0.5 to 0.8 gsm.

[0013] In some optional embodiments, the basis weight of the surface layer and the bottom layer is 30-45 gsm.

[0014] In some optional embodiments, in the step of papermaking the base paper, the amount of glue applied to the surface layer is 3.0-4.0 gsm; and the amount of glue applied to the bottom layer is 1.5-2.5 gsm.

[0015] In some optional embodiments, the filler content of the core layer is 5-10%.

[0016] In a second aspect, an embodiment of the present application provides a high-speed cartoning paperboard, which is prepared by the preparation method described in the above embodiment.

[0017] The preparation method of high-speed boxing paperboard provided in the embodiment of the present application can meet the high-speed packaging machine operation (packaging speed ≥ 300 boxes / min) by improving the pulp ingredients. In addition, while meeting the requirements of high resistance to folding and explosion and anti-explosion ink, it has good ink absorption, low paper wool and paper powder, excellent various coding effects, good boxing performance, good hot and cold glue, and can have good passability and exquisite appearance in the subsequent processing process. 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 a high-speed carton paperboard of the present application;

[0020] Figure 2 It is a schematic diagram of the stacking structure of an embodiment of the high-speed cartoning paperboard 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] In order to solve the problems of medicine packing and paper dust and lint, this patent, based on a full study of the fiber characteristics of long-fiber chemical pulp, short-fiber chemical pulp, and bleached chemical thermomechanical pulp, performs refined treatment on the pulp differently to give full play to the characteristics of each pulp. At the same time, the structure of the medicine pack paperboard is optimized to disperse the force structure of the paperboard, so that the paperboard is firm when it is boxed, without bursting or rebounding.

[0025] See also Figure 1 , Figure 1 It is a flow chart of an embodiment of a method for preparing high-speed carton paperboard of the present application, and the preparation method includes but is not limited to the following steps.

[0026] Step S100, making base paper.

[0027] See also Figure 2 , Figure 2 It is a schematic diagram of the stacking structure of an embodiment of the high-speed cartoning paperboard of the present application, wherein the base paper 100 in the embodiment of the present application includes a core layer 110, a surface layer 120 and a bottom layer 130; wherein the surface layer 120 and the bottom layer 130 have a basis weight of 30 to 45 gsm, specifically 30 gsm, 32 gsm, 35 gsm, 38 gsm, 40 gsm, 41 gsm, 43 gsm, 45 gsm, etc.

[0028] Optionally, the pulp of the core layer 110 includes 30%-50% BCTMP (bleached chemical thermomechanical pulp), 5%-10% NBKP (bleached kraft coniferous pulp), 20%-40% LBKP (bleached kraft hardwood pulp) and 15%-30% broken paper; the pulp of the surface layer 120 includes 30%-40% NBKP and 60%-70% LBKP; the pulp of the bottom layer 130 includes 20%-30% NBKP and 70%-80% LBKP.

[0029] Optionally, in this step, surface glue application may be performed on the surface layer 120 and the bottom layer 130 respectively, wherein the glue application amount of the surface layer is 3.0-4.0 gsm; and the glue application amount of the bottom layer is 1.5-2.5 gsm.

[0030] Please continue reading Figure 1 The preparation method in this embodiment further includes step S200, performing front coating on the surface layer; and step S300, performing back coating on the bottom layer.

[0031] In the process of front coating on the surface layer 120, three scraper coatings may be performed, namely, a primer 210, a middle coating 220 and a top coating 230, each coating amount is 8-100 gsm, and the total coating amount is 26-30 gsm. In the process of back coating on the bottom layer 130, a starch glue layer 300 may be applied, with a coating amount of 0.5-0.8 gsm.

[0032] The method for preparing high-speed box paperboard in the embodiment of the present application first adopts a three-layer fourdrinier paperboard. To ensure good anti-bending and anti-explosion performance, the surface layer and the bottom layer are quantitatively controlled to 30-45g / m 2 , using chemical wood pulp, taking advantage of the characteristics of pure wood pulp, such as long fiber, high strength, few impurities, good uniformity and good dispersion effect, to give the paperboard high stiffness and ensure the paper surface strength and anti-folding and explosion performance.

[0033] The NBKP in chemical wood pulp controls a relatively high freeness (the freeness of the original pulp is maintained between 600-700ml, and the fiber length is between 2.2mm-2.5mm). The processing technology is to use the existing 3 series pulping machines in the workshop for light circulation pulping, with a total pulping specific energy of about 80-100KWH / t, and grind the freeness of the long-fiber chemical pulp to 500-580ml. At this time, the fiber length is maintained between 2.0-2.3mm, and the content of fine fibers after light fibrillation is ≤5%. This lightly ground high-freeness long-fiber chemical pulp has the characteristics of being soft and flexible, and plays the role of a "skeleton", giving the cardboard softness and resistance to various wrinkles. At the same time, by taking advantage of the bulk and integrity of lightly ground chemical pulp, not only can the cardboard use less mechanical pulp to achieve the target thickness, but it can also reduce paper powder and paper hair through complete fibers and a low proportion of mechanical pulp, and reduce the frequency of cleaning paper powder in the subsequent processing. The preparation method in the embodiment of the present application controls the fiber fibrillation by pretreating the long-fiber chemical pulp to balance the softness, bulkiness and strength of the fiber and improve the performance of the fiber itself. In addition, the fibers after this light pre-refining are interwoven through the length of the fiber itself, there are a large number of pores between the fibers, the fibers are soft and elastic, and have good rebound after compression. The energy consumption of the refined pretreated pulp is reduced from 300KWH / t to 800-100KWH / t, and the dewatering performance on the machine is good. After the pretreatment technology of the NBKP used for the core layer, surface and bottom layer, the toughness of the NBKP can be increased, and the fiber strength can be guaranteed, so that the paperboard has a better boxing effect. Chemical wood pulp LBKP has the characteristics of moderate fiber thickness and low ash content, which reduces the wear of the paper cutter tool and fills the pores caused by the NBKP pulp, so that the paper surface remains uniform and smooth. The freeness is also controlled at a high level: 400-500ml.

[0034] In addition, the core filler dosage is 5-10%, and 30-50% BCTMP mechanical pulp is used to increase the bulk of the paperboard. BCTMP mechanical pulp adopts a new pulping process and has a high bulk (2.8-3.4g / m 3 ), and can maintain good strength, tensile strength ≥ 17N*m / g, the paperboard uses less mechanical pulp, the pulp is well mixed and uniform, the paperboard core layer has less fine fibers, and it is not easy to produce paper hair and paper powder. In addition, the core layer contains NBKP and LBKP, the strength is guaranteed to a certain extent, and the reinforcing drugs such as starch or dry strength agent can be added less, reducing the problem of paper brittleness caused by large amounts of such drugs.

[0035] Among them, the front sizing amount is 3.0-4.0gsm, which meets the requirements of various printing strengths. Three coats of scraper coating are performed on the front sizing surface, with a total coating amount of 26-30gsm; the coating amount of each coat is controlled at 8-10gsm. Three coats ensure a lower PPS (printing surface roughness) on the surface of the cardboard, improving the printing effect of the cardboard. At the same time, the lower coating amount makes basic preparations to ensure the proportion of base paper and the thickness of the cardboard, and also reduces the wear of the subsequent paper cutter and the generation of paper powder and paper hair. The amount of coating latex used for the three coats can be 13-15% (relative to the mass percentage of the pigment), the amount of porcelain clay in the front middle coating and top coating is 20-40%, and the amount of calcined clay is 10-20%. This formula can meet the needs of high-speed medicine packaging machines for ink bursting, and the printing and drying speed is fast, which is suitable for post-processing such as laser coding and UV inkjet coding.

[0036] The amount of glue applied on the back is controlled at 1.5-2.5gsm, a layer of starch glue is applied on the back, the coating amount is 0.5-0.8gsm, the solid content of the glue applied on the back is 10-14%, and the solid content of the starch glue applied on the back is 6-10%. It is mainly to ensure the pasting effect and paper state. The adhesive used by some medicine packaging machines for pasting medicine boxes is in particle form, which is instantly heated and sprayed onto the back of the paper through a spray gun. There will generally be a tooth knife line on the front. Due to the fast packaging speed, if the back is poorly open, the adhesive is not easy to penetrate, which can easily cause the problem of loose pasting. Therefore, it is necessary to control the amount of glue applied on the back and the amount of back coating. If the amount of glue applied on the back is too low, or the back coating is not applied, the paper is easy to warp, causing problems such as jamming or failure to load the machine during printing and subsequent processing.

[0037] Several specific embodiments are described below. For details, please refer to the following table, which compares the high-speed cartoning paperboard obtained by the parameters of the three embodiments of the present application with the ordinary paperboard in the conventional solution.

[0038] The high-speed carton paperboard in this embodiment has a basis weight of 300 gsm and a thickness of 430 um.

[0039]

[0040]

[0041] By comparing the above key parameters, it can be seen that the paperboard in the embodiment of the present application achieves the following effects:

[0042] 1. Improvement of stiffness (CD / MD stiffness increased by 5%): The paperboard in the embodiment of the present application adopts a structure in which the surface layer and the bottom layer use high-strength chemical wood pulp. The pretreatment technology maintains sufficient fiber thickness and length of the wood pulp, so that the surface and bottom layers form a loose, thick, elastic and tough fiber layer. The core layer mechanical pulp is used to form a stable structure of the paperboard, which has a strong force to resist bending by external forces. The chemical pulp treated in the usual way has serious fiber cutting, and the thickness and length become smaller, and it is impossible to form a mesh fiber layer structure with sufficient toughness and good elasticity.

[0043] 2. Improvement of box-forming performance, i.e., reduction of indentation stiffness: While the surface and bottom layers of the paperboard maintain elastic and tough wood pulp, the core layer uses a low proportion (30-50%) of high bulk (bulk 2.8-3.4) BCTMP mechanical pulp. After indentation treatment, the core layer mechanical pulp fibers are irreversibly broken under the pressure of the knife die rather than chemical pulp. The core layer is crushed and does not rebound, while the reticular structure of the surface and bottom layers is not destroyed, resulting in a smaller thickness at the indentation and a lower indentation stiffness, i.e., improved box-forming performance.

[0044] Note: Indentation stiffness is an indicator that simulates the rebound force after molding and crease in the packaging workshop, and is the main indicator for evaluating the box-making effect. To evaluate whether a paperboard has good box-making performance, it must have a certain stiffness and a low indentation stiffness. If the stiffness is low and the indentation stiffness is also low, the box surface of this paperboard is easy to sag after boxing; if a paperboard has high stiffness and high indentation stiffness, it will cause poor box folding when it is placed on the box folding machine, and the surface of the folded packaging box will bulge and it will easily fall apart.

[0045] 3. Reduction of paper dust and paper hair: Lower coating amount on the front side, high freeness NBKP and LBKP, low proportion (30-50%) and high bulk (bulk 2.8-3.4) BCTMP mechanical pulp, greatly reduce the fine fiber content and ash content in the paperboard, effectively reducing the source of paper dust and paper hair.

[0046] In addition, a folding box test is performed as follows. 1. Sample cutting: After confirming the longitudinal and transverse arrangement of the paper fibers, use the stiffness sheet sampler to cut 38mm*70mm paper sheets, and cut one sheet each along the longitudinal and transverse directions of the paper machine. 2. Indentation: Use an indentation knife with the specifications of knife width * groove depth * groove width 0.71*0.5*1.5 to indent the test piece. The processing method is to face the knife edge with the front side facing the long side and indent vertically. Use body gravity to press down for 1-2 seconds and then take it out. 3. Secondary sample cutting: Perform secondary trimming on the long side of the sample piece, leaving 15mm and 5mm widths on both sides of the indentation. 4. Indentation stiffness test: The front of the test piece faces the indentation stiffness test head, and the 5mm short side of the paper sheet is clamped into the indentation stiffness instrument. The instrument is reset to zero, and the test head is turned to perform an indentation test. 5. Effect observation: After taking down the tested sample, fold it at 90° and 60° according to the original test folding direction, and observe the folded corners with a 60x magnifying glass.

[0047] Among them, the indentation of the ordinary cardboard folding box in the conventional solution is not round, while the indentation of the cardboard folding box in the embodiment of the present application is well rounded.

[0048] The preparation method of high-speed cartoning paperboard provided in the embodiment of the present application can meet the high-speed packaging machine operation (packaging speed ≥ 300 boxes / min) by improving the pulp ingredients. In addition, while meeting the requirements of high folding and explosion resistance and anti-explosion ink, it has good ink absorption, low paper hair and paper powder, excellent various coding effects, good cartoning performance, good cold and hot glue, and can have good passability and exquisite appearance in the post-processing process. It has the characteristics of low mechanical pulp and low paper powder and paper hair of the same thickness, and also meets the use requirements of high-speed medicine packaging machines, and also meets a variety of inkjet and cold and hot glue processes.

[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 high-speed carton paperboard, characterized in that: The preparation method comprises: Papermaking base paper; wherein the base paper comprises a core layer, a surface layer and a bottom layer, and the pulp of the core layer comprises 30%-50% BCTMP, 5%-10% NBKP, 20%-40% LBKP and 15%-30% broken paper; Performing front coating on the surface layer; Back coating is performed on the base layer.

2. The preparation method according to claim 1, characterized in that: The pulp of the surface layer includes 30%-40% NBKP and 60%-70% LBKP.

3. The preparation method according to claim 2, characterized in that: The bottom layer of pulp comprises 20%-30% NBKP and 70%-80% LBKP.

4. The preparation method according to claim 1, characterized in that: The step of performing front coating on the surface layer comprises: performing three scraper coatings, namely, primer coating, middle coating and top coating, each coating amount is 8-100gsm, and the total coating amount is 26-30gsm.

5. The preparation method according to claim 4, characterized in that: The amount of porcelain clay in the coating of the middle coating and the top coating is 20-40%, the amount of calcined clay is 10-20%, and the amount of latex is 13-15%.

6. The preparation method according to claim 1, characterized in that: In the step of back coating on the bottom layer, a layer of starch glue is applied with a coating amount of 0.5 to 0.8 gsm.

7. The preparation method according to claim 1, characterized in that: The basis weights of the surface layer and the bottom layer are both 30-45 gsm.

8. The preparation method according to claim 1, characterized in that: In the step of making base paper, the amount of glue applied to the surface layer is 3.0-4.0 gsm; the amount of glue applied to the bottom layer is 1.5-2.5 gsm.

9. The preparation method according to claim 1, characterized in that: The filler dosage of the core layer is 5-10%.

10. A high-speed cartoning paperboard, characterized in that: The high-speed cartoning paperboard is prepared by the preparation method according to any one of claims 1 to 9.

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