CN113235324A

CN113235324A - Paperboard, production method thereof and cigarette packet box

Info

Publication number: CN113235324A
Application number: CN202110442386.1A
Authority: CN
Inventors: 周寅明; 田维实; 王俊明; 仇如全
Original assignee: Ningbo Asia Pulp and Paper Co Ltd
Current assignee: Ningbo Asia Pulp and Paper Co Ltd
Priority date: 2021-04-23
Filing date: 2021-04-23
Publication date: 2021-08-10

Abstract

The application discloses card paper, a production method thereof and a cigarette packet box. The paperboard comprises base paper, wherein the base paper comprises a surface layer, a core layer and a bottom layer which are sequentially stacked, the surface layer, the core layer and the bottom layer respectively comprise bleached long-fiber wood pulp, and the fiber length range of the bleached long-fiber wood pulp subjected to pretreatment is 2-2.3 mm. The fiber length that includes in each layer is longer, interweaves through the length of fibre self for the card paper has better deflection performance and toughness, can satisfy follow-up card paper and carry out processing operations such as cross cutting or folding box.

Description

Paperboard, production method thereof and cigarette packet box

Technical Field

The application relates to the technical field of papermaking, in particular to a paperboard, a production method thereof and a cigarette packet box.

Background

The lightweight paper product means that the basis weight of the base paper is reduced on the premise of ensuring that the thickness is not changed, and physical indexes such as stiffness, strength and the like are required to be not obviously changed. The light weight of the paper product has positive influence on reducing the unit consumption of paper fiber per ton and reducing the cost of paper per ton, can reduce the fiber consumption, saves the fiber resource and is more beneficial to environmental protection because the wood pulp consumption can be reduced. Therefore, weight reduction of paper is becoming an important direction for paper products.

The current lightweight universal technology is to add a large amount of mechanical pulp into the core layer of the paperboard, and the bulk of the paperboard is improved through the high bulk performance of the mechanical pulp. The lightweight paperboard prepared by the method has very high stiffness and insufficient flexibility, and the subsequent processing of the paperboard is seriously influenced.

Disclosure of Invention

The application mainly provides card paper, a production method thereof and a cigarette packet box, and aims to solve the problem that the lightweight card paper is insufficient in toughness.

In order to solve the technical problem, the application adopts a technical scheme that: providing a paperboard, which comprises base paper, wherein the base paper comprises a surface layer, a core layer and a bottom layer which are sequentially stacked; the surface layer, the sandwich layer and the bottom layer all comprise bleached long-fiber wood pulp, and the fiber length range of the pretreated bleached long-fiber wood pulp is 2-2.3 millimeters.

In some embodiments, the core layer is made of blended pulp comprising a blend of 50-70 mass percent bleached mechanical pulp, 5-10 mass percent bleached long fiber wood pulp, 5-20 mass percent bleached short fiber wood pulp, and 15-30 mass percent broke pulp.

In some embodiments, further comprising a liner layer positioned between the face layer and the core layer; the liner is made from a blend stock comprising bleached fluff wood pulp.

In some embodiments, the facing layer is made of mixed pulp formed by mixing 30-50% of bleached long-fiber wood pulp and 50-70% of bleached short-fiber wood pulp.

In some embodiments, the bottom layer is made of mixed pulp formed by mixing 30-50% of bleached long-fiber wood pulp and 50-70% of bleached short-fiber wood pulp.

In some embodiments, the surface of the facing layer is further provided with a coating layer, and the coating layer has a basis weight of 20-25 gsm. Where gsm (gram/Square Meter) is the weight unit of international paper grades.

In some embodiments, the coating layer includes a first coating layer and a second coating layer, the first coating layer being located between the top layer and the second coating layer, the first coating layer having a basis weight in the range of 10-15 gsm.

In order to solve the above technical problem, another technical solution adopted by the present application is: there is provided a method of producing a paperboard comprising: providing surface layer paper pulp, core layer paper pulp and bottom layer paper pulp; respectively making and dehydrating the surface layer paper pulp, the core layer paper pulp and the bottom layer paper pulp to form a corresponding surface layer fiber layer, a corresponding core layer fiber layer and a corresponding bottom layer fiber layer; laminating and compounding a surface layer fiber layer, a core layer fiber layer and a bottom layer fiber layer to obtain base paper, and drying and coating the base paper to obtain the paperboard; the providing of the face layer pulp, the core layer pulp and the base layer pulp comprises: providing bleached mechanical pulp, bleached long-fiber wood pulp, bleached short-fiber wood pulp and broke pulp respectively; pretreating the bleached long-fiber wood pulp to ensure that the freeness of the bleached long-fiber wood pulp is in the range of 500-580ml and the fiber length is 2-2.3 mm; and mixing the bleached mechanical pulp, the bleached long-fiber wood pulp, the bleached short-fiber wood pulp and the broke pulp according to a preset ratio to obtain the surface layer pulp, the core layer pulp and the bottom layer pulp.

In some embodiments, the step of pretreating the bleached pulp so that the freeness of the bleached pulp is in the range of 500-580ml and the fiber length is in the range of 2-2.3mm comprises: and circularly refining the bleached long-fiber wood pulp by using three serial refiners, wherein the total refining ratio can be 50-80 KWH/t.

In some embodiments, after formulating the resulting core layer pulp, further comprising: and adding positive starch into the core layer paper pulp, wherein the substitution degree of the positive starch is not less than 0.035%.

In some embodiments, the step of coating the paperboard base paper comprises: carrying out first coating treatment on the paperboard base paper, wherein the coating quantitative is 10-15 gsm; and carrying out a second coating treatment on the surface subjected to the first coating treatment, wherein the total coating weight of the two coating treatments is 20-25 gsm.

In some embodiments, the mixing the pulp according to the preset mixture ratio to obtain the core layer pulp comprises mixing, by mass, 50-70% of bleached mechanical pulp, 5-10% of bleached long fiber wood pulp, 5-20% of bleached short fiber wood pulp, and 15-30% of broke pulp, and uniformly stirring.

In some embodiments, the base paper further comprises a lining fiber layer, wherein the lining fiber layer is superposed and compounded with the surface layer fiber layer, the core layer fiber layer and the bottom layer fiber layer to obtain the base paper, wherein the fiber layer is positioned between the surface layer fiber layer and the core layer fiber layer; the surface layer fiber layer obtained by mixing the pulp according to the preset proportion comprises: according to the mass fraction, mixing 30-50% of bleached long-fiber wood pulp and 50-70% of bleached short-fiber wood pulp to obtain surface layer paper pulp, and dehydrating the surface layer paper pulp; the liner fibrous layer is made from bleached fluff wood pulp.

In some embodiments, the mixing the pulp according to the preset mixture ratio to obtain the bottom layer pulp comprises: according to the mass fraction, 30-50% of bleached long-fiber wood pulp and 50-70% of bleached short-fiber wood pulp are mixed and stirred uniformly.

In order to solve the above technical problem, another technical solution adopted by the present application is: the cigarette packet box comprises a paper component, and the paper component is prepared from the paperboard.

The beneficial effect of this application is: be different from prior art's condition, the cardboard that this application discloses includes the body paper, and the body paper is including surface course, sandwich layer and the bottom that stacks gradually, and all includes bleaching long fine wood pulp in surface course, sandwich layer and the bottom, and the fibre length scope after the bleaching long fine wood pulp through the preliminary treatment is 2-2.3 millimeters. During the longer bleaching long fine wood pulp of fibre length in each layer, interweave through the length of fibre self, there are a large amount of holes between the fibre for the fibre is soft elastic, and it is good to kick-back after the compression, has promoted the pliability of card paper, can satisfy subsequent processing operations such as card paper cross cutting or folding box.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts, wherein:

fig. 1 is a schematic structural diagram of an embodiment of a paperboard provided in the present application;

FIG. 2 is a schematic structural diagram of another embodiment of a card paper provided herein;

fig. 3 is a schematic flow chart of an embodiment of a method for producing a paperboard provided by the present application;

fig. 4 is a flowchart illustrating an embodiment of step S110.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that if directional indications (such as up, down, left, right, front, and back … …) are referred to in the embodiments of the present application, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indications are changed accordingly.

In addition, if there is a description of "first", "second", etc. in the embodiments of the present application, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present application.

The paperboard is also called paperboard, which is a general name of thick paper, and is mainly used as packaging paper and printing paper, such as packaging boxes, corrugated boxes, hang tags, cigarette packets, business cards, certificates, invitation cards, hand bags, envelopes, month calendars, post cards and the like, which can be produced by using the paperboard. The basis weight and performance requirements and processing requirements for paperboard vary depending on the intended use of the paperboard. When this application cardboard is as packing class products such as cigarette packet box, perhaps uses such as handbag, need print and subsequent processing to the cardboard, for example cross cutting, become box etc. consequently have certain requirement to performances such as the deflection of cardboard, indentation deflection, toughness, intensity.

The main raw material in the paper industry is paper pulp, and each layer of fibrous layer of cardboard in this application is made by papermaking after different kinds of paper pulp are mixed according to specific ratio, and the difference of used paper pulp kind and paper pulp ratio are different makes each fibrous layer have different characteristics to also make the cardboard have corresponding performance.

The paper pulp used in paper industry is mainly fibrous material prepared from plant fiber as raw material by different processing methods. The plant fibers in the pulp are mainly derived from wood, which provides 93% of the plant fibers worldwide. Pulp can be classified into chemical pulp, mechanical pulp and chemimechanical pulp according to different manufacturing processes. The chemical pulp is obtained by separating fiber and lignin by a chemical method, wherein the chemical method comprises a caustic soda method, a sulfate method, a sulfite method and the like. The mechanical pulp is paper pulp prepared by mechanically defibering fiber raw materials, and comprises millstone groundwood pulp, disc groundwood mechanical pulp, thermomechanical pulp and the like. Can be subdivided into bleached pulp, semi-bleached pulp and unbleached pulp (unbleached pulp) according to the processing depth. The fiber length division in the pulp can be divided into long fibers and short fibers, the long fibers can provide certain toughness of the paper, and the short fibers can provide the evenness of the fiber layer.

The starting materials, reagents or apparatuses used in the following examples are conventionally commercially available or can be obtained by conventionally known methods, unless otherwise specified.

Referring to fig. 1, fig. 1 is a schematic structural diagram of an embodiment of a paper jam provided in the present application. In this embodiment, the cardboard includes a base paper including a face layer 11, a core layer 12, and a base layer 13, which are sequentially stacked. The surface layer 11, the core layer 12 and the bottom layer 13 all comprise bleached long-fiber wood pulp, and the length range of fibers of the bleached long-fiber wood pulp after pretreatment is 2-2.3 mm.

Wherein the core layer 12 mainly provides the thickness of the card paper, and the surface layer 11 and the bottom layer 13 provide the necessary strength properties of the card paper, such as stiffness properties. Surface course 11, all bleach long-fiber wood pulp in sandwich layer 12 and the bottom 13, the fibre length scope after the preliminary treatment of bleach long-fiber wood pulp is 2-2.3 millimeters, also all contain the fibre of length scope 2-2.3 millimeters in each layer, longer fibre self has better toughness, and can interweave through the length of fibre self, there is a large amount of holes between the fibre after the interweaving, make the fibre soft elasticity, it is good to kick-back after the compression, the pliability of card paper has been promoted, make card paper can satisfy follow-up card paper and carry out processing operations such as cross cutting or folding box.

In one embodiment, the core layer 12 is made from a blend of pulps including bleached mechanical pulp, bleached long fiber pulp, bleached short fiber pulp, and broke pulp.

It should be noted that the bleached mechanical pulp described in the present application may be bleached chemithermomechanical pulp (hereinafter referred to as BCTMP) or alkaline hydrogen peroxide mechanical pulp (APMP). BCTMP is wood pulp with high yield which is obtained by soaking in mild chemicals, fine grinding and bleaching, the pulp yield can reach 85-90 percent, and is much higher than that of other chemical wood pulp (42-45 percent). APMP is chemi-mechanical pulp which adopts a novel pulping process, and is also wood pulp with high yield. Because the mechanical pulp has high lignin content, the fibers are not easy to swell, hydrate and fiberize during pulping, and are relatively coarse and hard, the fibers are not easy to cling to each other in the paper drying process, and the bulk of the formed paper can be improved. Furthermore, the BCTMP and the APMP have the characteristics of high utilization rate of raw materials, high bulk, low production cost and the like, and can improve the bulk, the opacity and the printing adaptability of the finished paper. Under the condition of the same quantitative quantity and thickness, compared with low-bulk mechanical pulp or chemical pulp, the high-bulk mechanical pulp can be used for obtaining the paperboard with higher bulk, namely the lightweight paperboard.

Bleached mechanical pulp can provide fiber layer thickness and high bulk, for example, APMP bulk of 3.2-3.6g/m³. But the fibrous structures formed by the bleached mechanical pulp also have the characteristics of low strength and more fiber bundles. If the bleached mechanical pulp is used alone to form a fibrous layer, the folding endurance is very poor and the tensile strength is also low. In particular, the fold endurance is even 0, while the tensile strength is less than 20N m/g. Therefore, the mixed pulp prepared in the core layer comprises other pulp besides the bleached mechanical pulp, such as bleached long-fiber wood pulp, bleached short-fiber wood pulp and broken pulp in a certain proportion, so that the strength properties such as stiffness, toughness, folding resistance and the like, and the evenness and the flatness of the fiber layer of the core layer are improved.

The bleached long-fiber wood pulp has the advantages that after the bleached long-fiber wood pulp is pretreated, the fiber length range is 2-2.3 millimeters, the fiber length is long, the bleached long-fiber wood pulp has high freeness, and the fiber layer can be endowed with folding resistance and softness. Specifically, the bleached long fiber wood pulp may be bleached kraft softwood pulp (hereinafter abbreviated as NBKP). The fiber length of the non-pretreated bleached long-fiber wood pulp can reach 2-3.5 mm, and the freeness can be kept between 600 and 700 ml.

In order to enhance the specific effect of the wood pulp, the bleached long fiber wood pulp can be pretreated to control the devillicate brooming of the fibers, improve the performance of the fibers, such as increasing the toughness of the long fibers and balancing the softness and strength of the fibers, so that the fibers have better strength and stiffness and better softness and flexibility. Specifically, the pretreatment of bleached long fiber wood pulp can be carried out with a mild refiner in series at a total refiner energy of about 50-80 KWH/t. After pretreatment, the free degree of the bleached long-fiber wood pulp is in the range of 500-580ml, and the fiber length is between 2.0 and 2.3 millimeters. The fibers with the length range of 2.0-2.3 mm are interwoven through the length of the fibers, and a large number of pores are formed among the fibers, so that the stiffness and toughness of the paperboard are improved, and the softness and elasticity of the fiber layer are also improved. The bleached long-fiber wood pulp with the freeness of 500-580ml is obtained after pretreatment, the fiber width is 27-29 microns, and the content of fine fibers is less than 5 percent. In addition, the 3 serial pulping machines are adopted for mild circulating pulping for pretreatment, so that the energy consumption is reduced.

The application bleached short fiber wood pulp has the characteristics of moderate fiber thickness and low ash content, and the short fibers are filled into the gaps of the fiber layer, for example, in filling the pores formed by the long fibers in the bleached long fiber wood pulp, the flatness of the fiber layer is increased, meanwhile, the mixed addition of the short fibers can avoid the overhigh toughness of the paperboard, the paperboard is not favorable for subsequent die cutting, folding and other processing operations, and the cutter abrasion of a paper cutter is reduced. Specifically, the bleached fluff wood pulp may be bleached kraft hardwood pulp (hereinafter abbreviated as "LBKP"), such as magnolia pulp.

The broke pulp described herein is a pulp of broke. Broke may be referred to as system recycled paper, which is waste paper produced during the paper making process. Broke as referred to in this application includes dry and wet broke, wherein dry broke refers in particular to broke occurring at the machine end and thereafter, and wet broke refers to broke occurring at wet ends, such as the wire and press sections. Therefore, the broke may include different pulp fibers, such as mechanical pulp fibers, long fibers or short fibers, used in the production of the cardboard, and the like, which can provide a certain amount of fibers to the core layer 12, and the mixed presence of different types of fibers can also enhance the core layer 12 with corresponding properties, such as bulk, stiffness and flexibility. Waste paper in the production process is treated to be damaged paper pulp, and the damaged paper pulp is mixed with other pulp according to a specific proportion, so that on the basis of ensuring the performance of a fiber layer after papermaking and finally forming paperboard, resource waste is avoided, the fiber resource is fully utilized, and the papermaking cost of a papermaking enterprise is reduced.

As can be seen from the above description, since the bleached mechanical pulp has a high bulk property, the pretreated bleached long fiber wood pulp has a good strength property and flexibility, the bleached short fiber wood pulp has a good uniformity, and the waste pulp is recycled, the core layer 12 made of the bleached mechanical pulp, the bleached long fiber wood pulp, the bleached short fiber wood pulp, and the waste pulp has a high bulk property, a good strength, and a good flexibility, and the surface of the core layer 12 has a good smoothness, and the recycled waste paper is used, so that resources are saved, and resource waste and environmental pollution are reduced.

In one particular embodiment, the components of the blended slurry from which core layer 12 is made include: the mass fraction of the bleached mechanical pulp is 50-70%, the mass fraction of the bleached long-fiber wood pulp is 5-10%, the mass fraction of the bleached short-fiber wood pulp is 5-20% and the mass fraction of the broken paper pulp is 15-30%. Specifically, for example, in some embodiments, the mass fraction of bleached mechanical pulp is 50%, 55%, 60%, 65%, 70%, etc.; the mass fraction of the bleached long-fiber wood pulp in the mixed pulp is 5%, 7%, 9%, 10% and the like; the mass fraction of the bleached fluff wood pulp is 5%, 10%, 15%, 20% and the like; the mass fraction of the broken paper pulp is 15%, 20%, 25%, 30% and the like. The mass fraction may also be referred to as mass fraction or mass percentage. For example, the mass fraction of the bleached mechanical pulp is the mass ratio of the bleached mechanical pulp in the mixed pulp corresponding to the core layer 12.

In another embodiment, the core layer 12 corresponds to a blend slurry including 50-70% BCTMP, 5-10% NBKP, 5-20% LBKP, and 15-30% broke. Wherein 50-70% BCTMP can provide sufficient thickness of the core layer and high bulk. The 5-10% NBKP provides long fiber and toughness of the core fiber layer, so that the tensile elongation at break and impact strength of the paperboard are high, and the problems of poor slurry strength and poor uniformity caused by the use of a large amount of BCTMP are solved. 5-20% LBKP provides the short fiber, and the mixed addition of short fiber makes the fibre distribution more even when the fibrous layer possesses certain toughness, provides the uniformity for the cardboard, can avoid cardboard toughness too high, is unfavorable for subsequent processing operations such as cross cutting and folding box of going on of cardboard. 15-30% damaged paper pulp realizes the recycle of waste paper, and energy is saved, and simultaneously, because the damaged paper pulp contains different mixed paper pulps, the properties of the core layer 12 such as stiffness, flexibility and the like can be increased to a certain extent.

In one embodiment, the facing layer 11 is made of mixed pulp including a mixture of bleached long fiber wood pulp and bleached short fiber wood pulp. The bleached long fiber wood pulp and the bleached short fiber wood pulp are the same as the bleached long fiber wood pulp and the bleached short fiber wood pulp of the core layer 12, and the detailed description is referred to the above and is not repeated herein.

Because the bleached long-fiber wood pulp has better stiffness and toughness and the bleached short-fiber wood pulp has better evenness, the mixed pulp formed by mixing the bleached long-fiber wood pulp and the bleached short-fiber wood pulp is made into the surface layer 11, and the surface layer has better strength properties such as stiffness, toughness and the like and flatness.

In a specific embodiment, the mass fraction of the bleached long fiber wood pulp in the mixed pulp for making the surface layer 11 is 30-50%; the mass fraction of the bleached fluff wood pulp is 50-70%. Specifically, for example, in some embodiments, the mass fraction of bleached softwood pulp is: 30%, 35%, 40%, 45%, 50%, etc.; the mass fraction of the bleached fluff wood pulp is as follows: 50%, 55%, 60%, 65%, 70%, etc.

In one embodiment, the bottom layer 13 is made of mixed pulp including a mixture of bleached fluff wood pulp and bleached fluff wood pulp. Similarly, the bleached long-fiber wood pulp has better stiffness and toughness, and the bleached short-fiber wood pulp has better evenness, so that the bottom layer 13 has better strength and flatness such as stiffness and toughness.

In a specific embodiment, the mass fraction of bleached long fiber wood pulp in the mixed pulp making up the bottom layer 13 is 30-50%; the mass fraction of the bleached fluff wood pulp is 50-70%. Specifically, for example, in some embodiments, the mass fraction of bleached softwood pulp is: 30%, 35%, 40%, 45%, 50%, etc.; the mass fraction of the bleached fluff wood pulp is as follows: 50%, 55%, 60%, 65%, 70%, etc.

In another embodiment, the bottom layer 13 is made of a blended slurry comprising 30-45% mass fraction NBKP and 55-70% mass fraction LBKP.

In all the above embodiments, the bleached softwood pulp is used in the surface layer 11, the core layer 12 and the bottom layer 13, the devillicate fibrillation of the fibers is controlled through pretreatment, the length range of the fibers is kept between 2 and 2.3 millimeters, the softness and the strength of the fibers are effectively balanced, and the fibers are interwoven through the length of the fibers, so that a large number of pores are formed among the fibers, and an elastic and flexible fiber layer is formed. In addition, the core layer 12 also includes bleached mechanical pulp, and the bleached long-fiber wood pulp and the mechanical pulp fiber cooperate to form a stable structure of the paperboard, so that the paperboard has strong external force bending resistance, and can meet the stiffness requirement of subsequent use and processing of the paperboard.

And, the bleached fluff wood pulp has better uniformity performance, mixes in surface course 11, sandwich layer 12 and the bottom 13 and adds the bleached fluff wood pulp and can make each layer make the fibre distribution more even when possessing certain toughness, provides the uniformity for the card paper, can avoid only using the long fiber to lead to card paper toughness too high, is unfavorable for subsequent card paper to carry out processing operations such as cross cutting cut off or folding box.

On the other hand, the core layer 12 has a high content of bleached mechanical pulp, up to 50-70%, giving the core layer 12 a high bulk and low strength (tensile strength not greater than 20N × m/g). After the indentation treatment, the mechanical pulp fiber of the core layer is subjected to irreversible fracture before the chemical pulp fiber under the same cutter die pressure. In the card paper, the core layer 12 is crushed without rebounding, and the net structures of the surface layer 11 and the core layer 12 are not damaged, so that the thickness of the indentation part is reduced, the indentation stiffness is reduced, and the folding treatment of the card paper is facilitated. Combine above-mentioned analysis, the card paper of this application has fine deflection and less indentation deflection, when becoming the box processing to the card paper, has promoted into the box performance.

In a specific embodiment, the face layer 11 is made of a mixed slurry formed by mixing NBKP including 35% mass fraction and LBKP including 65% mass fraction; the core layer 12 is made of mixed pulp formed by mixing 60 mass percent of BCTMP, 5 mass percent of NBKP, 10 mass percent of LBKP and 25 mass percent of broken paper pulp; the bottom layer 13 is made of a mixed slurry formed by mixing NBKP including 40% mass fraction and LBKP including 60% mass fraction. The core 12 uses 60% BCTMP pulp to increase the bulk of the board, while a large amount of mechanical pulp results in poor strength and formation of the core 12. And NBKP pulp with high freeness is used in the surface layer 11, the core layer 12 and the bottom layer 13, so that the folding resistance and softness of the paperboard are ensured. The NBKP pulp is pretreated to control the devillicate brooming of the fiber to balance the softness and strength of the fiber and improve the performance of the fiber, thereby ensuring the strength and flexibility of the paperboard.

In one embodiment, the surface of the face sheet 11 of the paperboard of the present application is further provided with a coating layer 14. Since the base paper includes the surface layer 11, the core layer 12, and the base layer 13, which are sequentially stacked, the coating layer 14 may be disposed on a surface of the base paper near the surface layer 11. The coating layer 14 basis weight can be 20-25gsm, specifically, can be 20, 21, 22, 23, 24, or 25 gsm. The lower coating weight provides a foundation for ensuring the proportion of the base paper and the thickness of the paperboard, and meanwhile, the paperboard with the lower coating weight also reduces the abrasion of the paper cutting machine and the generation of paper powder and paper dust during the subsequent paper cutting operation.

In one embodiment, the coating layer 14 may include a first coating layer 141 and a second coating layer 142, the first coating layer 141 being located between the face layer 11 and the second coating layer 142, the first coating layer 141 having a basis weight in the range of 10-15 gsm. The sum of the basis weights of the first and second coating layers 141 and 142 is in the range of 20-25 gsm. The two-layer coating is adopted, the coating weight is lower every time, and the total coating weight of two times is controlled in a lower range, so that a foundation is provided for ensuring the proportion of base paper and the thickness of the paperboard, and meanwhile, the paperboard with lower coating weight also reduces the abrasion of a paper cutting machine and the generation of paper powder and paper dust during subsequent paper cutting operation.

Referring to fig. 2, fig. 2 is a schematic structural diagram of another embodiment of a card paper provided in the present application. In this embodiment, the base paper further comprises a liner layer 22, the liner layer 22 being located between the face layer 21 and the core layer 23.

The surface layer 21 may refer to the description related to the surface layer 11 in fig. 1, and is not described herein again. Similarly, the core layer 23 and the bottom layer 24 refer to the description of the core layer 12 and the bottom layer 13 in fig. 1, respectively, and are not repeated here.

In one embodiment, the liner 22 is made from a blend pulp formed from a blend including bleached fluff wood pulp. The short fibers in the bleached short fiber wood pulp have the characteristics of moderate thickness and low ash content, and can fill the pores caused by long fiber pulp, so that the fiber layer and the paper surface are kept uniform and flat, and meanwhile, the cutter abrasion of the paper cutter can be reduced.

Wherein, the sandwich layer 23 mainly provides the thickness of card paper and the performance of high bulk, surface course 21, all include bleaching long fine wood pulp in sandwich layer 23 and the bottom 24, the fibre length scope after the bleaching long fine wood pulp through the preliminary treatment is 2-2.3 millimeters, longer fibre, length through fibre self is interweaved, the stiffness performance and the toughness of card paper have been increased, the mixed joining of short fiber makes each layer make the fibre distribute more evenly when possessing certain toughness, provide the evenness for the card paper, can avoid only using the long fiber to lead to card paper toughness too high, be unfavorable for subsequent card paper to carry out the processing operations such as cross cutting cut or folding box. The use of short fibers in the liner 22 balances the overall toughness and strength properties of the paperboard and provides paperboard uniformity. In addition, the base paper with the four-layer fiber layer structure adopted in the embodiment has better strength performance and stiffness performance due to the addition of the fiber layer, so that the paperboard can meet the operation and processing requirements of the high-speed cigarette packing machine. When subsequently folding the box operation to the card paper, the fibre separation between the layer of card paper crease position department is easier than the separation between the fibre of individual layer fibre, therefore the structure of four layers of fibre layers can form fuller crease radian, is favorable to the glue adhesion when becoming the box, can reduce the black risk of exploding when becoming the box.

In some embodiments, the paperboard further includes a coating layer 25, and the coating layer 25 is disposed on the surface of the face layer 21. Since the base paper includes the face layer 21, the under layer 22, the core layer 23, and the under layer 24, which are sequentially stacked, the coating layer 25 can also be said to be provided on the surface of the base paper on the side close to the face layer 21.

The detailed description of the coating layer 25 can refer to the related description of the coating layer 14 in fig. 1, and is not repeated herein.

In one embodiment, the coating layer 25 may include a first coating layer 251 and a second coating layer 252, the first coating layer 251 being located between the face layer 21 and the second coating layer 252, the first coating layer 251 having a basis weight in the range of 10-15 gsm. The sum of the basis weights of the first coating layer 251 and the second coating layer 252 is in the range of 20-25 gsm. The two-layer coating is adopted, the coating weight is lower every time, and the total coating weight of two times is controlled in a lower range, so that a foundation is provided for ensuring the proportion of base paper and the thickness of the paperboard, and meanwhile, the paperboard with lower coating weight also reduces the abrasion of a paper cutting machine and the generation of paper powder and paper dust during subsequent paper cutting operation.

In one implementation scenario, the paperboard is used to make a cigarette pack box. In the cardboard for a pack case, the basis weight of the face layer 21 is 25 to 30gsm, specifically, 25, 26, 27, 28, 29, and 30 gsm. The basis weight of the liner 22 is 10 to 15gsm, and specifically, may be 10, 11, 12, 13, 14, 15 gsm. The core layer 23 has a basis weight of 95 to 105gsm, and specifically, may be 95, 96, 98, 100, 102, 105 gsm. The basis weight of the backsheet 24 is 25 to 30gsm, specifically, 25, 26, 27, 28, 29, 30 gsm. The basis weight of the core layer 23 is much larger than that of other layers, and therefore, an important function of the core layer 23 is to provide a thickness index of the base paper and the cardboard.

In a specific implementation scenario, the surface layer 21 is made of a mixed slurry formed by mixing 30-50% of NBKP and 50-70% of LBKP; the liner 22 is made of a mixed slurry formed by mixing including LBKP; the core layer 23 is made of mixed pulp formed by mixing 50-70% of BCTMP, 5-10% of NBKP, 5-20% of LBKP and 15-30% of broken paper pulp; the bottom layer 24 is made of a mixed slurry formed by mixing 30 to 45 mass% of NBKP and 55 to 70 mass% of LBKP. The core layer 23 uses a large amount of BCTMP pulp to increase the bulk of the card paper. And NBKP pulp with high freeness is used in the surface layer 21, the core layer 23 and the bottom layer 24, so that the folding resistance and softness of the paperboard are ensured. The NBKP pulp is pretreated to control the devillicate brooming of the fiber to balance the softness and strength of the fiber and improve the performance of the fiber, thereby ensuring the strength and flexibility of the paperboard. And the use of LBKP with short fiber in each layer can provide smoothness of the paperboard and balance the strength and flexibility of the paperboard, so that the strength and flexibility of the paperboard are not too high. The finally formed paperboard has good stiffness and toughness and relatively low crease stiffness, not only has good box folding performance, but also can meet the operation and processing requirements of a high-speed cigarette packing machine.

The application also provides a production method of the paperboard. Referring to fig. 3, fig. 3 is a schematic flow chart of an embodiment of a method for producing a paperboard provided by the present application. The paperboard production method of the embodiment comprises the following steps:

step S110: a face layer pulp, a core layer pulp and a base layer pulp are provided.

Referring to fig. 4, fig. 4 is a flowchart illustrating an embodiment of step S110, specifically, step S110 includes:

step S111: bleached mechanical pulp, bleached long fiber wood pulp, bleached short fiber wood pulp, and broke pulp are provided, respectively.

The bleaching mechanical pulp can be bleaching chemical thermomechanical pulp (BCTMP) or alkaline hydrogen peroxide mechanical pulp (APMP), among others. BCTMP is wood pulp with high yield which is obtained by soaking in mild chemicals, fine grinding and bleaching, the pulp yield can reach 85-90 percent, and is much higher than that of other chemical wood pulp (42-45 percent). APMP is chemi-mechanical pulp which adopts a novel pulping process, and is also wood pulp with high yield. Because the mechanical pulp has high lignin content, the fibers are not easy to swell, hydrate and fiberize during pulping, and are relatively coarse and hard, the fibers are not easy to cling to each other in the paper drying process, and the bulk of the formed paper can be improved. Furthermore, the BCTMP and the APMP have the characteristics of high utilization rate of raw materials, high bulk, low production cost and the like, and can improve the bulk, the opacity and the printing adaptability of the finished paper. Under the condition of the same quantitative quantity and thickness, compared with the mechanical pulp with low bulk, the mechanical pulp with high bulk can be used for obtaining the paperboard with higher bulk, namely the lightweight paperboard. Although bleached mechanical pulp can provide fiber layer thickness and high bulk, such as APMP bulkCan reach 3.2-3.6g/m³. But the fibrous structures formed by the bleached mechanical pulp also have the characteristics of low strength and more fiber bundles. If the bleached mechanical pulp is used alone to form a fibrous layer, the folding endurance is very poor and the tensile strength is also low.

The length range of the fibers of the bleached long-fiber wood pulp after pretreatment is 2-2.3mm, the length of the fibers is longer, and the bleached long-fiber wood pulp has higher freeness and can endow the fiber layer with folding resistance and softness. In particular, the bleached long fiber wood pulp may be bleached kraft softwood pulp (NBKP).

Bleached short fiber wood pulp has the characteristics of moderate fiber thickness and low ash content, and short fibers are filled into gaps of the fiber layer, for example, in filling holes formed by long fibers in the bleached long fiber wood pulp, the fiber layer is increased to increase the flatness, meanwhile, the mixed addition of the short fibers can avoid the overhigh toughness of the paperboard, is not favorable for subsequent die cutting, box folding and other processing operations of the paperboard, and reduces the cutter abrasion of a paper cutter. In particular, the bleached fluff wood pulp may be bleached kraft hardwood pulp (LBKP), such as magnolia pulp.

The broke pulp is the pulp of broke. Broke may be referred to as system recycled paper, which is waste paper produced during the paper making process. Broke as referred to in this application includes dry and wet broke, wherein dry broke refers in particular to broke occurring at the machine end and thereafter, and wet broke refers to broke occurring at wet ends, such as the wire and press sections. Thus, the broke may include different pulp fibers, such as mechanical pulp fibers, long fibers or short fibers, used in the production of cardboard, and the different types of fibers mixed in the broke provide corresponding enhanced properties of the mixed pulp, such as bulk, stiffness and flexibility. Waste paper in the production process is treated to be damaged paper pulp, and the damaged paper pulp is mixed with other pulp according to a specific proportion, so that on the basis of ensuring the performance of a fiber layer after papermaking and finally forming paperboard, resource waste is avoided, the fiber resource is fully utilized, and the papermaking cost of a papermaking enterprise is reduced.

Step S112: the bleached long-fiber wood pulp is pretreated, so that the freeness of the bleached long-fiber wood pulp is in the range of 500-580 ml.

The fiber length of the non-pretreated bleached long-fiber wood pulp can reach 2-3.5 mm, and the freeness can be kept between 600 and 700 ml. The method is characterized in that the bleached long-fiber wood pulp is pretreated, the freeness of the bleached long-fiber wood pulp is controlled within the range of 500-580ml, meanwhile, the devillicate brooming of the fibers is controlled, the softness and the strength of the fibers are balanced, and the performance of the fibers is improved, such as the toughness of long fibers is increased.

In one embodiment, the pre-treatment of bleached pulp can be carried out by subjecting the bleached pulp to mild refiner recirculation using three refiners in series, the total refiner energy being about 50-80 KWH/t.

The conventional refining pretreatment of the long-fiber wood pulp can generally realize the refining total ratio of 250-300KWH/t, the freeness of the long-fiber wood pulp obtained by the pretreatment is about 300ml, the length of the long-fiber wood pulp is only 1.9-2.1 mm, the fiber surface is highly devillicate and broomed, and simultaneously, a plurality of fibers are cut off, and the obtained long-fiber wood pulp has high strength, good folding resistance and folding resistance times of more than 1500. However, the long-fiber wood pulp has many hydrogen bonds, the fibers are tightly combined, and the long-fiber wood pulp is not soft and has poor resilience after being stressed. And the fiber is cut seriously, the thickness and the length become small, and a reticular fiber layer structure with enough toughness and good elasticity cannot be formed.

In the embodiment, the pretreatment mode of mild circulating refining by three serial refiners enables the freeness of the bleached long-fiber wood pulp to be in the range of 500-580ml, wherein the fiber length is between 2.0 and 2.3 millimeters. The fibers in the 2.0-2.3 mm length range are interwoven by the length of the fibers themselves, with a large number of voids between the fibers. At the same time, the sufficient thickness of the fibers is ensured, and the width or thickness of the fibers is 27-29 microns. The devillicate brooming of the fiber is controlled by the pretreatment mode, the softness and the strength of the fiber are balanced, and the performance of the fiber is improved. The long-fiber paper pulp has proper strength and folding resistance (the folding resistance times are 50-100 times), better stiffness and toughness, better softness and softness, and good rebound resilience after pressing. The bleached long-fiber wood pulp with the freeness of 500-580ml is obtained after pretreatment, the content of fine fibers is less than 5 percent, and the occupation ratio of long fibers is high. In addition, compared with the traditional pulping pretreatment, the energy consumption is reduced, and the on-machine dehydration performance is good.

Step S113: and mixing the bleached mechanical pulp, the pretreated bleached long-fiber wood pulp, the bleached short-fiber wood pulp and the damaged paper pulp according to a preset ratio to obtain surface layer paper pulp, core layer paper pulp and bottom layer paper pulp.

In one embodiment, the step of mixing pulp according to a predetermined ratio to obtain surface layer pulp comprises: according to the mass fraction, 30-50% of bleached long-fiber wood pulp and 50-70% of bleached short-fiber wood pulp are mixed to obtain surface layer paper pulp. The 30-50% bleached long-fiber wood pulp provides long fibers, has higher freeness, and can endow the fiber layer with folding resistance, softness, certain strength performance and higher toughness. The bleached short-fiber wood pulp of 50-70% can fill up the pores formed by long fibers in the bleached long-fiber wood pulp, the flatness of the fiber layer is increased, the balance of the toughness of the surface layer fiber layer is realized with the bleached long-fiber wood pulp, the processing operations of die cutting, box folding and the like which are not favorable for subsequent paperboard cutting due to overhigh toughness are avoided, and the cutter abrasion of a paper cutter can be reduced.

In other specific embodiments, the step of mixing pulp according to a preset ratio to obtain core layer pulp includes: according to the mass fraction, 50-70% of bleached mechanical pulp, 5-10% of bleached long-fiber wood pulp, 5-20% of bleached short-fiber wood pulp and 15-30% of damaged paper pulp are mixed and stirred uniformly to obtain core layer paper pulp. Of these, 50-70% bleached mechanical pulp can provide sufficient thickness of the core layer as well as high bulk. The 5-10% bleached long-fiber wood pulp provides long fibers, and the toughness of the core fiber layer is improved, so that the tensile elongation at break and the impact strength of the paperboard are higher, and the problems of poor strength and poor uniformity of the pulp caused by the use of a large amount of bleached mechanical pulp are solved. 5-20% bleaching short fiber wood pulp provides the short fiber, and the mixed addition of short fiber makes the fibre distribution more even when the fibrous layer possesses certain toughness, provides the uniformity for the card paper, can avoid card paper toughness too high, is unfavorable for subsequent processing operations such as cross cutting and folding the box of carrying on of card paper. 15-30% broken paper pulp realizes the recycling of waste paper, saves energy, and simultaneously can increase the performances of stiffness, flexibility and the like of the core layer to a certain extent due to the fact that the broken paper pulp contains different mixed paper pulps.

In other specific embodiments, the step of mixing pulp according to a preset ratio to obtain bottom layer pulp comprises: according to the mass fraction, 30-50% of bleached long-fiber wood pulp and 50-70% of bleached short-fiber wood pulp are mixed and stirred uniformly to obtain bottom layer paper pulp. The 30-50% bleached long-fiber wood pulp provides long fibers, has higher freeness, and can endow the fiber layer with folding resistance, softness, certain strength performance and higher toughness. The bleached short-fiber wood pulp of 50-70% can fill up the pores formed by long fibers in the bleached long-fiber wood pulp, the flatness of the fiber layer is increased, the balance of the toughness of the surface layer fiber layer is realized with the bleached long-fiber wood pulp, the processing operations of die cutting, box folding and the like which are not favorable for subsequent paperboard cutting due to overhigh toughness are avoided, and the cutter abrasion of a paper cutter can be reduced.

In some embodiments, the surface layer pulp, the core layer pulp and the bottom layer pulp obtained in step S113 may further include an additive to make the paperboard have better performance or to facilitate papermaking. The auxiliary agent is auxiliary chemicals, comprises a retention and drainage aid, a defoaming agent, a dispersing agent, a dry strength agent, a surface treating agent and the like, and can be selectively added according to the demand of the paperboard.

In one embodiment, after the core layer pulp is prepared, positive starch is added to the core layer pulp, and the substitution degree of the positive starch is not less than 0.035%, for example, 0.04%, 0.05%, 0.06% and the like. The positive starch with the substitution degree of more than or equal to 0.035% has enough hydroxyl groups, can be fully combined with fiber, and improves the retention of the positive starch. The addition of the positive starch or the cationic starch increases the interlayer strength of the fiber layer, and the addition of a certain amount can improve the interlayer strength to 150-200J/m²And simultaneously contributes to the lifting of stiffness.

Before the positive starch is added into the core layer paper pulp, the positive starch can be cooked for 5-10min at the temperature of 130-140 ℃ to prepare starch paste with the solid content of 3 percent, and then the starch paste is diluted into the starch paste with the solid content of 0.3-0.4 percent by using warm water and then added into the core layer paper pulp. The adding amount of the positive starch is calculated by pure starch, 3-5kg of the positive starch can be added into each ton of paper pulp, the adding amount of the positive starch is controlled in a small range, and the situation that a formed core fiber layer is brittle and easy to break due to excessive adding is avoided.

Step S120: and respectively making the surface layer paper pulp, the core layer paper pulp and the bottom layer paper pulp and dehydrating to form a corresponding surface layer fiber layer, a corresponding core layer fiber layer and a corresponding bottom layer fiber layer.

Step S130: and laminating and compounding the surface layer fiber layer, the core layer fiber layer and the bottom layer fiber layer to obtain base paper, and drying and coating the base paper to obtain the paperboard.

In this embodiment, the higher bleaching long fiber wood pulp of intensity is used to the surface course and the bottom of body paper, and the preprocessing technique of long fiber wood pulp makes wood pulp keep enough fibre thickness and length, makes surface course and bottom form the fibre layer of bulk elasticity and toughness, cooperates the mechanical thick liquid of high bulk in the sandwich layer, forms the body paper that has stable structure, and the body paper has the bending of the anti external force of stronger dynamics, has higher stiffness performance. On the other hand, while the surface layer and the bottom layer maintain elasticity and toughness, the core layer uses a large amount of bleached mechanical pulp with high bulk (bulk 3.4-3.6) and low strength (tensile strength is not more than 20N x m/g), after the indentation treatment, the mechanical pulp fiber of the core layer generates non-recoverable fracture before the chemical pulp fiber under the pressure of a knife die, the core layer is crushed and does not rebound, but simultaneously the reticular structures of the surface layer and the bottom layer are not damaged, so that the thickness of the indentation part is reduced, the indentation stiffness is reduced, and the box forming performance is improved.

In a specific embodiment, the step of subjecting the base paper to a coating treatment specifically comprises: and coating the front surface of the base paper twice, wherein the two coating treatments are coated on the surface of one side, close to the surface layer, of the base paper. Wherein, the first coating is used for carrying out first coating treatment on the paperboard base paper, and the coating quantitative is 10-15 gsm. And carrying out a second coating treatment on the surface subjected to the first coating treatment, wherein the total coating weight of the two coating treatments is 20-25 gsm. The coating adopts the coating commonly used in the paper-making industry, and the coating treatment can ensure that the paper has good surface gloss and smoothness so as to provide excellent appearance performance and printing adaptability, meet the requirements of subsequent processing, die cutting and box packaging, and finally obtain exquisite external packaging effect. The two layers have smaller coating ration, so that the proportion of the base paper can be ensured, the basic preparation is provided for the thickness of the paperboard, and meanwhile, the abrasion of a subsequent paper cutter and the generation of paper powder and paper dust are reduced due to the lower coating weight. When the conventional coating is coated on the front surface of the base paper, the coating of the conventional coating is not carried out on the back surface of the base paper, namely the surface of the base paper close to the bottom layer, but starch glue coating is carried out. It is considered that, when the base paper is subjected to the coating process, the front side is subjected to a normal coating operation, and the back side of the base paper is subjected to a sizing operation.

In other embodiments, the front side of the base paper may be coated once or more than twice. Specifically, the total coated basis weight of the front side of the base paper may be controlled in the range of 20-25 gsm. The reverse side of the base paper can be coated conventionally according to the needs. In this case, in the coating process, the normal coating operation can be performed on both the front and back sides of the base paper.

In some embodiments, it is also necessary to size both sides of the base paper before coating, and to dry and hard-press the base paper. After the coating process, the card paper is subjected to soft calendering and winding, and finally the card paper with high box forming property, high bulk and light weight is obtained.

In another embodiment, the base paper comprises a lining layer fiber layer besides the surface layer fiber layer, the core layer fiber layer and the bottom layer fiber layer, and the fiber layer is positioned between the surface layer fiber layer and the core layer fiber layer. The base paper is obtained by laminating and compounding a surface layer fiber layer, a lining layer fiber layer, a core layer fiber layer and a bottom layer fiber layer. Wherein, the lining fiber layer is obtained by carrying out papermaking and dehydration treatment on lining paper pulp. The liner pulp comprises bleached fluff wood pulp. The paperboard prepared by the embodiment has the advantages that the base paper comprises four fiber layers including the surface layer, the lining layer, the core layer and the bottom layer which are sequentially stacked, and the paperboard has better strength performance and stiffness performance due to the addition of the fiber layer, so that the operation and processing requirements of a high-speed cigarette packing machine can be met. When subsequently folding the box operation to the card paper, the fibre separation between the layer of card paper crease position department is easier than the separation between the fibre of individual layer fibre, therefore the structure of four layers of fibre layers can form fuller crease radian, is favorable to the glue adhesion when becoming the box, can reduce the black risk of exploding when becoming the box.

The following is a further description with reference to specific examples.

The cardboards of comparative examples 1-2 and examples 1-3 were prepared according to the production method of the cardboard provided by the present application. The base papers of the cardboards of comparative examples 1-2 and examples 1-3 are composed of four fiber layers, i.e., a surface layer, a lining layer, a core layer and a bottom layer. The fiber composition in each layer comprises different types of fibers and the mass proportion of the different types of fibers in the fiber layer, and can be embodied and expressed by the types of different wood pulps mixed in the paper pulp corresponding to each layer of fiber layer and the proportion of the different wood pulps. The pulp composition of each fiber layer in comparative examples 1-2 and examples 1-3 is shown in table 1. In the category, N represents bleached long fiber pulp NBKP, L represents bleached short fiber pulp LBKP, BCTMP represents bleached mechanical pulp, and Broke represents Broke pulp.

Table 1:

wherein the quantitative ratios of the cardboards of the comparative examples 1-2 and the examples 1-3 are both 200-205g/m²In the range of 6.7 to 7.0% moisture, in the range of 3.5 to 311 μm thickness, and in the range of 1.48 to 1.52cm bulk³Each having a high bulk.

In addition, the cardboard of comparative examples 1-2 and examples 1-3 was tested for properties, including stiffness and indentation stiffness, and the number of folds. See table 2 for experimental data. Wherein CD stands for cross direction (CrossDirection), MD stands for machine direction (machine direction), the paper filament directions are divided into machine direction and cross direction according to the different orientation of the paper fiber arrangement, the direction of the paper fiber consistent with the paper machine running direction is called machine direction MD, and the direction perpendicular to the paper machine running is called cross direction CD.

Table 2:

test item	Comparative example 1	Comparative example 2	Example 1	Example 2	Example 3
						Stiffness CD/(mN/m)	2.71	2.61	2.88	2.95	3.10
Stiffness MD/(mN/m)	7.51	7.30	7.80	8.10	8.40
						Folding resistant CD/CD	38	24	46	55	60
Folding endurance MD/time	117	99	134	142	155
						Indentation stiffness CD/g	38	36	30	33	32
Indentation stiffness MD/g	45	42	36.1	39	38

The comparison of the experimental data shows that: the NBKP freeness of the comparative example 2 and the examples 1 to 3 are both in the range of 500-580ml, and the NBKP fiber length is longer and reaches 2-2.3mm, so that the cardboard of the comparative example 2 and the examples 1 to 3 has better transverse and longitudinal indentation stiffness, namely better folding box performance compared with the cardboard of the comparative example 1. In addition, the NBKP freeness in comparative example 2 was in the range of 500-580ml, but the NBKP slurry content was small in the slurry ratio of each layer, and the NBKP slurry was not included in the core layer. And compared with the comparative example 2, the proportion of NBKP is increased in the proportion of the surface layer pulp, the lining layer pulp, the core layer pulp and the bottom layer pulp in the embodiment 1 by adopting the pulp proportion provided by the application, so that the folding resistance of the paperboard is better, and the paperboard has better stiffness and smaller indentation stiffness. The freeness of the paperboard of the embodiment 2 and the embodiment 3 is in the range of 500-580ml, and the pulp proportion of each layer is in the range provided by the application, so that the paperboard has better transverse and longitudinal stiffness; both have a lower indentation stiffness and a better folding endurance than the comparative examples. Wherein, the folding endurance is positively correlated with the folding endurance.

The application also provides a cigarette packet box, and the cigarette packet box includes the paper part, and wherein the paper part is prepared by the card paper that the application provided. Because the card paper that this application provided has high bulk, better deflection, toughness and intensity performance, has less indentation deflection simultaneously, can be applicable to high-speed tobacco bale packagine machine. The high-speed processing of the paperboard can be realized through the high-speed cigarette packet packing machine, and the paperboard is processed into cigarette packet boxes. The cardboard has better deflection and lower indentation deflection, and the condition that the box face is sunken appears in the tobacco bale box after the box that better deflection can avoid the deflection undersize to lead to, also avoids the too high folding box that leads to of deflection not smooth simultaneously to and avoid the tobacco bale box surface after folding to bulge, the condition of easily scattering.

Further, cardboard that provides through this application can be prepared into hard box and soft box, that is to say that the cardboard that this application provided can satisfy the processing mode of two kinds of differences of the hard box of tobacco bale and the soft box of tobacco bale, can satisfy the stiffness requirement and the thickness requirement of hard box packagine machine and soft box packagine machine to card paper processing.

And the high bulk of card paper has also realized the lightweight of cigarette package box, outside guaranteeing that basic performance such as card paper thickness, deflection, printing effect satisfy the demand, realized the lighter characteristics of weight, when resources are saved, more can reduce burden for the packing, for the enterprise festival reduces the paper cost.

The above description is only an example of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings, or which are directly or indirectly applied to other related technical fields, are intended to be included within the scope of the present application.

Claims

1. The paperboard comprises base paper, wherein the base paper comprises a surface layer, a core layer and a bottom layer which are sequentially stacked; the surface course the sandwich layer with all include bleaching long fiber wood pulp in the bottom, its characterized in that, the fibre length scope of bleaching long fiber wood pulp after the preliminary treatment is 2-2.3 millimeters.

2. A paperboard according to claim 1, wherein said core layer is made of a mixed pulp comprising a mixture of 50-70% by mass of bleached mechanical pulp, 5-10% by mass of said bleached long fiber wood pulp, 5-20% by mass of bleached short fiber wood pulp and 15-30% by mass of broke pulp.

3. A paperboard according to claim 1 further comprising a liner layer, said liner layer being located between the face layer and the core layer; the liner is made of blended pulp formed by blending bleached fluff wood pulp.

4. A paperboard according to claim 1 wherein said face layer is made of a blended pulp comprising a blend of 30-50% by mass of said bleached long fiber wood pulp and 50-70% by mass of bleached short fiber wood pulp.

5. A paperboard according to claim 1 wherein said base layer is made of a mixed pulp comprising 30 to 50 mass% of said bleached long fiber wood pulp and 50 to 70 mass% of bleached short fiber wood pulp.

6. A paperboard according to claim 1, further comprising a coating layer disposed on the surface of said face layer, said coating layer having a basis weight of 20-25 gsm.

7. A paperboard according to claim 6, wherein said coating layer comprises a first coating layer and a second coating layer, said first coating layer being located between said face layer and said second coating layer, said first coating layer having a basis weight in the range of 10-15 gsm.

8. A method of producing paperboard comprising:

providing surface layer paper pulp, core layer paper pulp and bottom layer paper pulp;

respectively making the surface layer paper pulp, the core layer paper pulp and the bottom layer paper pulp and performing dehydration treatment to form a corresponding surface layer fiber layer, a corresponding core layer fiber layer and a corresponding bottom layer fiber layer;

superposing and compounding the surface layer fiber layer, the core layer fiber layer and the bottom layer fiber layer to obtain base paper, and drying and coating the base paper to obtain the paperboard;

characterized in that, the surface layer paper pulp, the core layer paper pulp and the bottom layer paper pulp are provided with:

providing bleached mechanical pulp, bleached long-fiber wood pulp, bleached short-fiber wood pulp and broke pulp respectively;

pretreating the bleached long-fiber wood pulp to ensure that the freeness of the bleached long-fiber wood pulp is in the range of 500-580ml and the fiber length is 2-2.3 mm;

and mixing the bleached mechanical pulp, the pretreated bleached long-fiber wood pulp, the bleached short-fiber wood pulp and the four pulp of the broke pulp according to a preset ratio to obtain the surface layer pulp, the core layer pulp and the bottom layer pulp.

9. A method for producing a paperboard according to claim 8 wherein said step of pretreating said bleached pulp to make it have a freeness of 500-580ml and a fiber length in the range of 2-2.3mm comprises:

and circularly refining the bleached long-fiber wood pulp by using three serial refiners, wherein the total refining ratio can be 50-80 KWH/t.

10. A method for producing a paperboard according to claim 8, further comprising, after preparing the resulting core layer pulp: and adding positive starch into the core layer paper pulp, wherein the substitution degree of the positive starch is not less than 0.035%.

11. A method for producing a cardboard according to claim 8, characterized in that the step of coating the cardboard base paper comprises:

carrying out first coating treatment on the paperboard base paper, wherein the coating quantitative is 10-15 gsm;

and carrying out a second coating treatment on the surface subjected to the first coating treatment, wherein the total coating weight of the two coating treatments is 20-25 gsm.

12. A method for producing a paperboard according to any one of claims 8 to 11, wherein said mixing to obtain said core layer pulp in a predetermined ratio comprises,

mixing 50-70% of the bleached mechanical pulp, 5-10% of the bleached long-fiber wood pulp, 5-20% of the bleached short-fiber wood pulp and 15-30% of the broke pulp according to mass fraction, and uniformly stirring.

13. A paperboard production method according to any one of claims 8-11, further comprising a lining fiber layer, wherein the lining fiber layer is laminated and compounded with the surface layer fiber layer, the core layer fiber layer and the bottom layer fiber layer to obtain a base paper, wherein the lining fiber layer is located between the surface layer fiber layer and the core layer fiber layer;

the surface layer fiber layer obtained by mixing the pulp according to the preset proportion comprises: according to the mass fraction, mixing 30-50% of bleached long-fiber wood pulp and 50-70% of bleached short-fiber wood pulp to obtain surface layer paper pulp, and papermaking and dewatering the surface layer paper pulp;

the liner fiber layer is made of a liner pulp comprising the bleached fluff wood pulp.

14. A method for producing a paperboard according to any one of claims 8 to 11, wherein the mixing to obtain the bottom layer pulp according to a predetermined ratio comprises:

according to the mass fraction, 30-50% of bleached long-fiber wood pulp and 50-70% of bleached short-fiber wood pulp are mixed and stirred uniformly.

15. A cigarette packet carton comprising a paper component, characterized in that said paper component is prepared from a cardboard as claimed in any one of claims 1 to 7.