阅读说明：本技术 一种卡纸及其生产方法 (Card paper and production method thereof ) 是由 徐镔烽 仇如全 田维实 王俊明 蒋燕飞 于 2020-10-22 设计创作，主要内容包括：本申请公开了一种卡纸及其生产方法。该卡纸包括原纸,原纸包括依次层叠的面层、面衬层、芯层和底层,底层为本色纤维层,本色纤维层包括本色长纤维和本色短纤维。本申请提供的卡纸,四层纤维层结构的原纸比传统三层纤维层多了一层纤维层,使卡纸具有更好的强度性能和挺度性能,能够形成更加饱满的折痕弧度,有利于成盒时的胶水粘连,降低成盒时的爆墨风险。底层为本色纤维层,具有较好的环保性能。(The application discloses card paper and a production method thereof. This card paper includes the body paper, and the body paper is including surface course, surface lining layer, sandwich layer and the bottom that stacks gradually, and the bottom is true qualities fibre layer, and true qualities fibre layer includes true qualities long fiber and true qualities short fiber. The application provides a card paper, four layers of fiber layer structure's body paper has more one deck fibre layer than traditional three-layer fibre layer, makes card paper have better intensity performance and deflection performance, can form fuller crease radian, glue adhesion when being favorable to becoming the box reduces the black risk of exploding when becoming the box. The bottom layer is a natural color fiber layer, and has better environmental protection performance.)

1. The paperboard is characterized by comprising base paper, wherein the base paper comprises a surface layer, a surface lining layer, a core layer and a bottom layer which are sequentially stacked;

the bottom layer is a natural color fiber layer, and the natural color fiber layer comprises natural color long fibers and natural color short fibers.

2. A paperboard according to claim 1, wherein the mass percentage of the natural color long fibers is 15 to 25% and the mass percentage of the natural color short fibers is 75 to 85%.

3. A paperboard according to claim 1, wherein said paperboard includes a coating applied to a surface of said face layer on a side thereof remote from said facing layer.

4. The paperboard according to claim 1, wherein the top layer is a bleached fiber layer, the bleached fiber layer comprises bleached chemical long fibers and bleached chemical short fibers, the mass percentage of the bleached chemical long fibers is 15-30%, and the mass percentage of the bleached chemical short fibers is 70-85%.

5. The paperboard according to claim 1, wherein the top liner layer is a bleached fiber layer, the bleached fiber layer comprises bleached chemical long fibers and bleached chemical short fibers, the mass percentage of the bleached chemical long fibers is 15-30%, and the mass percentage of the bleached chemical short fibers is 70-85%.

6. The paperboard according to claim 1, wherein the core layer is a bleached fiber layer, the bleached fiber layer comprises 0-10% by mass of bleached long chemical fiber, 30-55% by mass of bleached short chemical fiber, and 45-70% by mass of bleached mechanically ground fiber.

7. A paperboard according to claim 1, wherein the mass percentage of the face layer is 6-12%, the mass percentage of the face liner layer is 6-12%, the mass percentage of the core layer is 40-70%, and the mass percentage of the base layer is 6-12%.

8. A method of producing paperboard, comprising:

respectively preparing paper pulp of the surface layer, the surface lining layer, the core layer and the bottom layer according to a preset paper pulp ratio, and respectively manufacturing each layer by paper;

respectively dehydrating the surface layer, the surface lining layer, the core layer and the bottom layer to form fiber layers;

compounding the four fiber layers one by one through a compounding roller to form paperboard base paper;

wherein the one-by-one compounding sequence is the surface layer, the surface lining layer, the core layer and the bottom layer in sequence.

9. A paperboard production method according to claim 8, wherein the pulp of the bottom layer is unbleached pulp, the unbleached pulp comprises unbleached long fiber chemical pulp and unbleached short fiber chemical pulp, the freeness of the unbleached long fiber chemical pulp is 250-300 ml, and the freeness of the unbleached short fiber chemical pulp is 250-300 ml.

10. A method of producing a paperboard according to claim 8 wherein said core layer pulp comprises bleached short staple chemical pulp; the freeness of the bleached short-fiber chemical pulp is 200-400 ml.

Technical Field

The application relates to the technical field of papermaking, in particular to card paper and a production method thereof.

Background

Paper-making enterprises can generate a large amount of waste water in the paper-making process, and the waste water contains a large amount of harmful substances, wherein the waste water generated in the bleaching process is serious in environmental pollution. Taking the packaging base paper as an example, the packaging base paper used for cigarette boxes, strips, tongues and the like in the current market is mainly coated white cardboard and coated paper, and the paper pulp suitable for producing the two kinds of paper is bleached. The waste water generated after bleaching treatment contains various toxic substances, such as toxic carcinogen AOX (adsorbable Organic Halogen), dioxin and the like, and the waste water can meet the environmental protection requirement after being subjected to complex treatment, so that the environmental protection pressure of paper making enterprises and the economic investment in the environmental protection aspects of waste water treatment and the like are increased.

Paperboard is a strong, thick, high basis weight paper that is commonly used as packaging paper or printing paper. Under the condition of ensuring the requirement of specific application, how to ensure the performance requirement of the paperboard, meet the subsequent processing requirement, and carry out the production of the paperboard in an environment-friendly way is a difficult problem for paper-making enterprises.

Disclosure of Invention

The application mainly provides card paper and a production method thereof, and aims to solve the problems that the performance requirement of the card paper cannot be guaranteed and the subsequent processing requirement cannot be met under the condition that the requirement of specific application is guaranteed, and the production environment pollution is large.

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 surface lining layer, a core layer and a bottom layer which are sequentially stacked; the bottom layer is made of unbleached pulp which comprises unbleached long fiber chemical pulp and unbleached short fiber chemical pulp.

In some embodiments, the mass percent of the unbleached long fiber chemical pulp in the unbleached pulp is 15-25%, and the mass percent of the unbleached short fiber chemical pulp is 75-85%.

In some embodiments, the paperboard includes a coating applied to a surface of the face ply on a side thereof remote from the face ply.

In some embodiments, the surface layer is made of bleached long fiber chemical pulp and bleached short fiber chemical pulp, wherein the mass percentage of the bleached long fiber chemical pulp is 15-30%, and the mass percentage of the bleached short fiber chemical pulp is 70-85%.

In some embodiments, the top lining layer is made of bleached long fiber chemical pulp and bleached short fiber chemical pulp, wherein the mass percent of the bleached long fiber chemical pulp is 15-30%, and the mass percent of the bleached short fiber chemical pulp is 70-85%.

In some embodiments, the core layer is made of bleached long fiber chemical pulp, bleached short fiber chemical pulp and bleached mechanical pulp, wherein the mass percentage of the bleached long fiber chemical pulp is 0-10%, the mass percentage of the bleached short fiber chemical pulp is 30-55%, and the mass percentage of the bleached mechanical pulp is 45-70%.

In some embodiments, the face layer has a basis weight of 15-25 gsm, the face liner has a basis weight of 15-25 gsm, the base layer has a basis weight of 15-25 gsm, and the core layer has a basis weight of 110-130 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: respectively preparing paper pulp of the surface layer, the surface lining layer, the core layer and the bottom layer according to a preset paper pulp ratio, and respectively manufacturing each layer by paper; respectively dehydrating the surface layer, the surface lining layer, the core layer and the bottom layer to form a fiber layer; compounding the four fiber layers one by one through a compound roller to form paperboard base paper; wherein, the surface layer, the surface lining layer, the core layer and the bottom layer are sequentially compounded one by one.

In some embodiments, the bottom layer is made of unbleached pulp, the unbleached pulp comprises unbleached long fiber chemical pulp and unbleached short fiber chemical pulp, the freeness of the unbleached long fiber chemical pulp is 250-300 ml, and the freeness of the unbleached short fiber chemical pulp is 250-300 ml.

In some embodiments, the pulp from which the core layer is made comprises bleached short fiber chemical pulp; the freeness of the bleached short-fiber chemical pulp is 200-400 ml.

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, surface lining layer, sandwich layer and the bottom that stacks gradually, and the body paper of four layers of fiber layer structure has more one deck fibre layer, makes the card paper have better intensity performance and deflection performance, can make the card paper can satisfy the operation processing requirement of high-speed cigarette chartered plane. 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 bottom layer is a natural color fiber layer, so that the environment-friendly performance is better, the natural color pulp is used for partially or completely replacing bleached chemical pulp or bleached mechanical pulp, the use amount of bleached paper pulp can be reduced, and the waste water generated in the bleaching process is reduced, so that the environment-friendly pressure of a papermaking enterprise and the economic investment on environment protection are reduced. The natural color fiber layer of the bottom layer comprises natural color long fibers and natural color short fibers, and the natural color fibers contain more lignin, so that the fiber stiffness of the natural color fibers is higher than that of the conventional bleached chemical pulp. Wherein the toughness of card paper is provided to the true qualities long fiber, makes card paper tensile elongation at break and shock resistance great, and the mixture of true qualities short fiber adds and makes the fibre distribution more even when can make the bottom fibre layer possess certain toughness, provides the evenness for the card paper, can avoid only using the true qualities 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.

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 flow chart of an embodiment of a method for producing a paperboard provided in the present application;

fig. 3a and 3b are scanning electron micrographs of the crease line effect of cardboards with different interlayer strengths, respectively.

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.

Paperboard is a generic name of a thick paper between paper and paperboard, and is mainly used as packaging paper and printing paper, such as packaging boxes, corrugated boxes, hang tags, tobacco packets, business cards, certificates, invitation cards, hand bags, covers, month calendars, post cards and the like, which can be produced by using paperboard. Depending on the requirements of the cardboard such as the weight and the printing, the production cost of the cardboard may be different, and the cardboard with high production cost is generally used for packaging high-end goods or specific goods. The basis weight and performance requirements and processing requirements for paperboard vary depending on the intended use of the paperboard.

For convenience of understanding, the cardboard for cigarette packaging is described as an example, however, the cardboard provided by the present application and the production method thereof are not limited to be used as the cardboard for cigarette packaging, and in other embodiments, the cardboard can be used as a production packing box or a hand bag. Hereinafter, for convenience of description, the cigarette is wrapped with a paperboard, referred to as a cigarette card.

The main raw material in the paper industry is paper pulp, each fiber layer of the paperboard is made by mixing different kinds of paper pulp according to a specific proportion, and different characteristics of each fiber layer are caused by different kinds of paper pulp and different proportions of the paper pulp.

The paper pulp is a fibrous substance prepared by using plant fibers as raw materials through 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 in the pulp can be divided into long fibers and short fibers, wherein the long fibers provide toughness of the paper, and the short fibers provide evenness.

Referring to fig. 1, fig. 1 is a schematic structural diagram of an embodiment of a paperboard provided in the present application. The paperboard mainly comprises base paper and a coating 11, wherein the base paper comprises four fiber layers, namely a surface layer 12, a surface lining layer 13, a core layer 14 and a bottom layer 15. The surface layer 12, the surface lining layer 13, the core layer 14 and the bottom layer 15 are sequentially laminated, and the coating layer 11 is coated on the surface of the surface layer 12 far away from the surface lining layer 13. Wherein the face ply 12, face liner 13 and base ply 15 provide the necessary strength properties of the paperboard and the core ply 14 provides the thickness of the paperboard.

In the paperboard base paper, the mass percent of the surface layer 12 is 6-12%, the mass percent of the surface lining layer 13 is 6-12%, the mass percent of the core layer 14 is 40-70%, and the mass percent of the bottom layer 15 is 6-12%. That is, the mass percentage of the core layer 14 is larger than that of the other single layers, and an important function of the core layer 14 is to provide a thickness index of the base paper and the cardboard.

In a specific implementation scenario, the base paper weight range of the paperboard for cigarette packaging is 190-250 gsm, and the specific base paper weight range can be 200gsm, 210gsm, 220gsm, 225gsm, 230gsm, 240gsm and the like. The basis weight of the surface layer 12 is 15-25 gsm, the basis weight of the surface lining layer 13 is 15-25 gsm, the basis weight of the core layer 14 is 110-130 gsm, and the basis weight of the bottom layer 15 is 15-25 gsm. Where gsm (gram/Square Meter) is the weight unit of international paper grades.

Face layer 12 is a bleached fiber layer that includes both bleached chemical long fibers and bleached chemical short fibers. Wherein the mass percentage of the bleaching chemical long fibers in the surface layer fiber layer is less than that of the bleaching chemical short fibers in the surface layer fiber layer. Preferably, the mass percentage of the bleached chemical long fiber in the surface layer fiber layer is 15-30%, and the mass percentage of the bleached chemical short fiber in the surface layer fiber layer is 70-85%. Wherein the long fiber provides the toughness of fibrous layer to make card paper tensile elongation at break and shock resistance great, and the mixed of short fiber is added and is made the fibre distribution more even when can make the fibrous layer possess certain toughness, provides the uniformity for the card paper, can avoid card paper toughness too high, is unfavorable for the follow-up processing operations such as cross cutting and folding the box of going on of card paper.

The face-lining layer 13 is a bleached fiber layer including bleached chemical long fibers and bleached chemical short fibers. Wherein the mass percentage of the bleached chemical long fibers in the face liner fiber layer is less than the mass percentage of the bleached chemical short fibers in the face liner fiber layer. Preferably, the mass percentage of the bleached chemical long fiber in the surface lining fiber layer is 15-30%, and the mass percentage of the bleached chemical short fiber in the surface lining fiber layer is 70-85%. Wherein the long fiber provides the toughness of fibrous layer to make card paper tensile elongation at break and shock resistance great, and the mixed of short fiber is added and is made the fibre distribution more even when can make the fibrous layer possess certain toughness, provides the uniformity for the card paper, can avoid card paper toughness too high, is unfavorable for the follow-up processing operations such as cross cutting and folding the box of going on of card paper.

In one embodiment, the fibrous layer composition of the top layer 12 and the top liner layer 13 may be the same, that is, the top layer 12 and the top liner layer 13 may have the same mass percentage of the bleached chemical long fibers and the bleached chemical short fibers, for example, each having 20% of the bleached chemical long fibers and 80% of the bleached chemical short fibers. The amounts of the top sheet 12 and the top sheet 13 may be the same.

The core layer 14 is a bleached fiber layer that includes bleached chemical staple fibers and bleached mechanically milled fibers. Optionally, the mass percentage of the bleached chemical staple fiber in the core fiber layer is 30-55%, and the mass percentage of the bleached mechanical defibering fiber in the core fiber layer is 45-70%. The bleached fiber layer of the core layer 14 may further include bleached chemical long fiber, and optionally, the bleached chemical long fiber is 0 to 10% by mass in the core layer fiber layer. The bleached mechanical defibrination is bleached mechanical pulp, which can be bleached chemical thermomechanical pulp (BCTMP) or alkaline hydrogen peroxide mechanical pulp (APMP), wherein the BCTMP is high-yield wood pulp obtained by soaking in mild chemicals, fine grinding and bleaching, the pulp yield can reach 85-90%, and is much higher than that of other chemical wood pulps (42-45%), and the APMP is wood pulp obtained by pulping and bleaching simultaneously, and is also high-yield wood pulp. Because the mechanical pulp has high lignin content, the fibers are not easy to swell, hydrate and fiberize during pulping, the fibers are harder and harder, and the fibers are not easy to cling to each other in the drying process of the paper, so the bulk of the formed paper can be improved. And 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 ration and thickness, compared with the mechanical pulp with low bulk, the mechanical pulp with high bulk can be used for obtaining the paperboard with high bulk, and the paperboard has better stiffness performance, and wrinkle resistance and folding resistance.

The high bulk is a specific physical index of the light weight of the paper product, the light weight of the 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 meanwhile, physical indexes such as stiffness, strength and the like are required to be not obviously changed, the high bulk paperboard has positive influence on reducing the unit consumption of paper fiber per ton and the cost of paper per ton, the fiber consumption can be reduced, the fiber resource is saved, and the environment protection is facilitated because the wood pulp consumption can be reduced. In order to increase the bulk of the cardboard, the bulk of the cardboard is made to be 1.45cm or more³Per g, it is possible to use bleached mechanical pulps having a high bulk, for example a bulk of 3.2cm or more³BCTMP per gram and increasing the mechanical pulp dosage, as appropriate, for example, 45 to 70 mass percent BCTMP is used for the core layer 14. The proportion of the mechanical pulp in the core layer 14 can be adaptively adjusted according to the basis weight and thickness of the paperboard, and meanwhile, the performance requirements of the paperboard such as high bulk, stiffness and the like are guaranteed.

The bottom layer 15 is a natural color fiber layer, and the natural color fiber layer comprises natural color long fibers and natural color short fibers. And the mass percentage of the natural color long fibers in the natural color fiber layer is less than that of the natural color short fibers in the natural color fiber layer. Preferably, the mass percent of the natural color long fiber is 15-25%, and the mass percent of the natural color short fiber is 75-85%. The bottom layer 15 is a natural color fiber layer, has good environmental protection performance, and uses natural color pulp to partially or completely replace bleached chemical pulp or bleached mechanical pulp, so that the use amount of bleached paper pulp can be reduced, and the waste water generated in the bleaching process is reduced, thereby reducing the environmental protection pressure of paper-making enterprises and the economic investment on environmental protection. The natural color fibers of the bottom layer 15 contain more lignin, and the fiber stiffness or fiber rigidity is higher than that of the conventional bleached chemical pulp, so that the paperboard is provided with higher stiffness and rigidity. But the fixed quantity of the bottom layer 15 cannot be too high, and needs to be controlled in a proper range, such as 15-25 gsm, so that the paperboard has better stiffness, and the box folding effect and the ink burst phenomenon at the crease after printing cannot be influenced due to the overlarge stiffness or rigidity of the paperboard. Wherein the toughness of card paper is provided to the true qualities long fiber, makes card paper tensile breaking elongation and shock resistance great, and the mixture of true qualities short fiber adds and makes the fibre distribution more even when can make the bottom fibre layer possess certain toughness, provides the evenness for the card paper, can avoid only using the true qualities long fiber to lead to card paper toughness too high, is unfavorable for the follow-up processing operations such as cross cutting and roll over the box of card paper. The bottom layer 15 has a proper quantitative ratio to the pulp, so that the paperboard can meet certain strength, stiffness and toughness, can adapt to subsequent processing operation of the paperboard, and can be processed on high-speed equipment. The devillicate fibrillation of the unbleached pulp can be more sufficient by adjusting the freeness of the unbleached fibers in the bottom layer 15, and good hydrogen bond bonding effect can be formed among the fibers. Meanwhile, the bulk of the natural color long fibers and the natural color short fibers is controlled within a certain range, such as 1.3-1.45 cm3/g, and the bulk level of the bleached chemical pulp is achieved. Not only ensures the strength performance of the chemical pulp, but also improves the flexibility of the natural color fiber. Fibrillation refers to the phenomenon that fiber cell walls are fluffed, torn, devillicated, broomed and the like after paper pulp is beaten in pulping and papermaking production.

Among them, the freeness referred to in this application is the Canadian Standard Freeness (CSF), which is one of the methods for measuring the drainage performance of pulp.

The lignin is also called lignin, and in the plant cell wall, the lignin is a network structure high molecular polymer formed by the connection of phenylpropane monomers (p-hydroxyphenyl, guaiacyl and syringyl) through covalent bonds and is used for strengthening plant tissues. In wood, lignin acts as a filling and binding substance, in the wood cell wall, physically or chemically binding and strengthening between cellulose fibers, increasing the mechanical strength of the wood and its resistance to microbial attack.

The card paper in this embodiment includes four-layer structure's base paper, compares with traditional three-layer base paper, has increased facing layer 13. The base paper with the four-layer fiber layer structure is provided with one more fiber layer, so that the paperboard has better strength performance and stiffness performance. 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. Therefore, under the condition of the same indentation depth and width, the paperboard manufactured by adopting four layers of paper making has better box folding effect compared with the paperboard manufactured by three layers of paper making. The setting that each layer thick liquid was joined in marriage, for example the proportion of long fiber and short-staple, the setting of the proportion of mechanical thick liquid and chemical thick liquid for the cardboard of this application is tall in deflection, folding endurance is good, has also guaranteed the planarization of cardboard simultaneously. The surface layer 12, the surface lining layer 13 and the bottom layer 15 are quantitatively mixed with pulp to ensure the strength and optical properties of the finished paper, such as folding strength, tensile strength, tearing strength, whiteness and the like. The basis weight of the core layer 14 is set not only to ensure the interlayer strength and the like, but more importantly, to provide the desired thickness characteristics and high bulk characteristics to the paperboard.

When this application cardboard was used as cigarette package, handbag etc. needs to carry out printing and subsequent processing to the cardboard, for example cross cutting, become box etc.. The card paper that has four layers of fibre layer body paper structure in this embodiment has higher deflection, and the structure of four layers of fibre layer can form fuller crease radian, and the glue adhesion when being favorable to becoming the box can reduce the black risk of exploding when becoming the box. The ink explosion means that the paperboard can be bent by 90 degrees or 180 degrees after being subjected to die cutting and indentation processing, and the printing ink at the indentation position is exploded.

In one embodiment, the paperboard is a cigarette packaging paperboard, and the paperboard of the present application is required to be printed, die cut, and boxed. The paperboard comprising the four layers of fiber base paper has higher stiffness and smaller indentation stiffness, can meet the operation processing requirement of a high-speed cigarette packet machine, can be used for processing the paperboard by using the high-speed cigarette packet machine, and can remarkably improve the packaging efficiency due to the fact that the packaging speed of the high-speed cigarette packet machine is high and is usually more than or equal to 1200 packets/min.

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 12, surface course 13, sandwich layer 14 and the bottom 15 that stacks gradually, and the body paper of four layers of fiber layer structure has had one deck fibre layer more, makes the cardboard have better intensity performance and deflection performance, can make the operation processing requirement that the cardboard can satisfy high-speed cigarette chartered plane. 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 bottom layer 15 is a natural color fiber layer, has good environmental protection performance, and uses natural color pulp to partially or completely replace bleached chemical pulp or bleached mechanical pulp, so that the use amount of bleached paper pulp can be reduced, and the waste water generated in the bleaching process is reduced, thereby reducing the environmental protection pressure of paper-making enterprises and the economic investment on environmental protection. The natural color fiber layer of the bottom layer 15 comprises natural color long fibers and natural color short fibers, and the natural color fibers contain more lignin, so that the fiber stiffness of the natural color fibers is higher than that of the conventional bleached chemical pulp. Wherein the toughness of card paper is provided to the true qualities long fiber, makes card paper tensile elongation at break and shock resistance great, and the mixture of true qualities short fiber adds and makes the fibre distribution more even when can make the bottom fibre layer possess certain toughness, provides the evenness for the card paper, can avoid only using the true qualities 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.

Referring to fig. 2, fig. 2 is a schematic flow chart of an embodiment of a method for producing a paperboard provided by the present application. The production method of the paperboard comprises the following steps:

s101: and respectively preparing paper pulp of the surface layer, the surface lining layer, the core layer and the bottom layer according to a preset paper pulp ratio, and respectively manufacturing each layer by paper.

The surface layer paper pulp comprises 15-30% of bleached long fiber chemical pulp and 70-85% of bleached short fiber chemical pulp. The surface lining paper pulp comprises 15-30% of bleached long fiber chemical pulp and 70-85% of bleached short fiber chemical pulp. The core layer comprises 0-10% of bleached long fiber chemical pulp, 30-55% of bleached short fiber chemical pulp and 45-70% of bleached mechanical pulp. The bottom layer comprises 15-25% of natural color long fiber chemical pulp and 75-85% of natural color short fiber chemical pulp. The above percentages are mass percentages.

In each layer paper pulp, the long fiber provides toughness, makes the fibrous layer or make the tensile breaking elongation and the shock resistance increase of card paper, and the mixed addition of short fiber makes the fibre distribution more even when making the fibrous layer possess 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 the follow-up processing operations such as cross cutting and the box of folding of card paper.

The bleached mechanical pulp in the core layer can be bleached chemithermomechanical pulp (BCTMP) or Alkaline Peroxide Mechanical Pulp (APMP), which is a high-yield wood pulp with high bulk, and thus the resulting card paper also has the characteristic of high bulk. The core layer uses the bleached mechanical pulp with high bulk, so that the fiber quantity required by the paperboard for reaching the same performances of thickness, strength and the like is reduced, fiber resources can be saved, and the environment is better protected because the wood pulp consumption can be reduced. The freeness of the bleached short fiber chemical pulp is controlled to be 350 +/-50 ml in the core layer, so that hydrogen bonds among fibers of the core layer are in a proper range, and the bonding strength among layers is controlled to be in a certain range, thereby avoiding that the crease lines are not full due to overlarge or undersize bonding strength among the layers, further influencing the box folding effect or causing coating bursting, ink explosion of printing layers and the like.

The bottom layer uses unbleached pulp to partially or completely replace bleached chemical pulp or bleached mechanical pulp, so that the use amount of bleached paper pulp can be reduced, and the waste water generated in the bleaching process is reduced, thereby reducing the environmental protection pressure of paper-making enterprises and the economic investment on environmental protection. The natural color fiber of the bottom layer contains more lignin, and the fiber stiffness or the fiber rigidity is higher than that of the conventional bleached chemical pulp, so that the paperboard has higher stiffness and rigidity. But the bottom layer ration can not be too high, needs to be controlled in a proper range, such as 15-25 gsm, so that the paperboard has better stiffness, and the box folding effect and the ink explosion phenomenon at the printed crease can not be influenced due to the stiffness or the overlarge stiffness of the paperboard. Wherein the toughness of card paper is provided to the true qualities long fiber, makes card paper tensile breaking elongation and shock resistance great, and the mixture of true qualities short fiber adds and makes the fibre distribution more even when can make the bottom fibre layer possess certain toughness, provides the evenness for the card paper, can avoid only using the true qualities long fiber to lead to card paper toughness too high, is unfavorable for the follow-up processing operations such as cross cutting and roll over the box of card paper. The proper quantitative ratio of the bottom layer and the pulp can enable the paperboard to meet certain strength, stiffness and toughness, can adapt to subsequent processing operation of the paperboard, and can be processed on high-speed equipment.

The paper pulp of each layer can be added with an auxiliary agent to make the paperboard have better performance or be more beneficial to papermaking. The auxiliary agent is auxiliary chemical, including retention and drainage aid, defoaming agent, dispersing agent, dry strength agent, surface treating agent, etc. The dry strength agent can be used for increasing the strength of paper and the interlaminar strength, and can be cationic starch, Polyacrylamide (PAM) and the like.

Before the paper pulp of each layer is mixed according to a specific proportion, the paper pulp before mixing can be disc-milled, the freeness of the paper pulp and the bulk of the fiber layer can be adjusted by controlling the disc-milling power, namely the specific energy of the disc mill, so that the strength performance of the paper pulp is ensured, the fiber is softened, and the flexibility of the fiber is improved.

Specifically, the influence of the disc grinding power on the freeness and the bulk of the natural-color long fiber is as follows:

disc mill specific energy (kwh/t)	Freeness (ml)	Bulk (cm)3/g)
			0	700	1.6
380	300	1.45
			435	280	1.40
480	270	1.35
			515	250	1.30

Different disc grinding specific energy can carry out disc grinding on the unbleached long fiber chemical pulp, so that the unbleached pulp has different freeness and bulk. Along with the increase of the specific energy of the disc mill, the freeness of the unbleached pulp is reduced, and the bulk is correspondingly reduced. If the disc grinding specific energy is controlled to be 380-515 kwh/t, the freeness of the natural color long fiber pulp can be 300-350 ml, and the bulk is 1.3-1.45 cm³(ii) in terms of/g. And detecting the thickness and the quantification of the natural color long fiber layer, and dividing the thickness by the quantification to obtain a bulk thickness value.

The fiber of bottom unbleached pulp is thicker, the compliance is relatively poor, if directly make cigarette card with unbleached pulp as the bottom fiber, the folding endurance can be comparatively poor, the problem such as black is exploded to the box of easy appearance, through carrying out the disc grinding to unbleached pulp in this embodiment, control disc grinding specific energy, thereby adjust the freeness and the bulk of unbleached pulp, if the disc grinding specific energy of control unbleached long fiber thick liquid is at 380 ~ 515kwh/t, make the freeness at 250 ~ 300ml, it is 30 ~ 80kwh/t higher than the disc grinding specific energy that ordinary bleaching chemical long fiber of control reaches same freeness needs. The disc grinding specific energy of the natural color short fibers is controlled to be 140-210 kwh/t, the freeness can be controlled to be 300-350 ml, and the disc grinding specific energy required by the ordinary chemical short fibers to achieve the same freeness is 20-50 kwh/t higher. The freeness makes the devillicate of the unbleached pulp more sufficient, and the fibers can form good hydrogen bond combination effect. Meanwhile, the bulk of the natural color long fibers and the natural color short fibers is controlled to be 1.3-1.45 cm3/g, and the bulk level of the bleached chemical pulp is achieved. Not only ensures the strength performance of the chemical pulp, but also improves the flexibility of the natural color fiber.

S102: and respectively dehydrating the surface layer, the surface lining layer, the core layer and the bottom layer to form a fiber layer.

S103: and compounding the four fiber layers one by one through a compounding roller to form the paperboard base paper. Wherein, the surface layer, the surface lining layer, the core layer and the bottom layer are sequentially compounded one by one.

The base paper formed after compounding can be subjected to pre-drying, sizing, drying and hard-calendering, and is coated on the surface layer of the base paper to form a coating. The cardboard is further printed, die cut and boxed.

The card paper that forms in this embodiment, including the body paper of this four-layer fiber layer structure of surface course, sandwich layer and bottom, make card paper have better intensity performance and deflection performance and less crease deflection, can make card paper can satisfy the operation processing requirement of high-speed cigarette chartered plane. 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 paperboard base paper formed in the embodiment has higher stiffness and smaller indentation stiffness, the longitudinal stiffness can be greater than or equal to 7.2mN.m, the transverse stiffness can be greater than or equal to 3.2mN.m, the longitudinal indentation stiffness can be less than or equal to 60g, and the transverse indentation stiffness can be less than or equal to 55 g. In addition, the interlayer bonding strength can be controlled within a certain range by controlling the front sizing amount and the freeness of the chemical short fibers in the core layer, and the like, which belongs to the field of economy and production cost savingA control method. Specifically, the front sizing amount is controlled to be 1.5-3.0 gsm, the freeness of the chemical short fibers for the core layer is controlled to be 350 +/-50 ml and other conditions, and the interlayer bonding strength of the paperboard is controlled to be 150-200J/m²Within the range. The front surface here refers to the side of the base paper facing away from the facing layer. The paperboard with high and low stiffness and indentation stiffness and proper interlayer bonding strength can meet the operation requirement of a high-speed cigarette packaging machine, can be formed into a box more efficiently, and improves the production efficiency.

The relationship between the interlayer strength and the crease effect can be seen in fig. 3a and 3b, and fig. 3a and 3b are scanning electron micrographs of the crease line effect of the cardboard with different interlayer strength. The interlayer strength of the cardboard 1 corresponding to FIG. 3a is 235J/m²The indentation stiffness is large, the white coating cracks more seriously, and the crease effect is poor. The interlayer strength of the jam paper 2 corresponding to FIG. 3b is 178J/m²The interlaminar strength is relatively small, the indentation stiffness is small, the white coating bursts less, the broken points of the coating are less, and the crease effect is good. Wherein, the paper pulp proportion and the ration of each layer of the fiber layer of the cardboard 1 and the cardboard 2 are the same. Specifically, the difference between the interlayer strength of the cardboard 1 and the cardboard 2 can be adjusted by adjusting the dry strength agent added into the pulp.

The bottom layer of the paperboard in the embodiment is the unbleached fiber layer, so that the paperboard has good environmental protection performance, unbleached pulp is used for partially or completely replacing bleached chemical pulp or bleached mechanical pulp, the use amount of bleached paper pulp can be reduced, and the waste water generated in the bleaching process is reduced, so that the environmental protection pressure of a papermaking enterprise and the economic investment on environmental protection are reduced. The natural color fiber layer of the bottom layer comprises natural color long fibers and natural color short fibers, and the natural color fibers contain more lignin, so that the fiber stiffness of the natural color fibers is higher than that of the conventional bleached chemical pulp. Wherein the toughness of card paper is provided to the true qualities long fiber, makes card paper tensile elongation at break and shock resistance great, and the mixture of true qualities short fiber adds and makes the fibre distribution more even when can make the bottom fibre layer possess certain toughness, provides the evenness for the card paper, can avoid only using the true qualities 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.

In another embodiment, the basis weight of the cardboard 3 and the cardboard 4 are the same, and are both 215gsm, and both comprise base paper of a four-layer fiber layer structure. Preparing paper pulp of the surface layer, the surface lining layer, the core layer and the bottom layer according to the paper pulp proportion in the table, and manufacturing each layer by paper. The paperboard 3 uses conventional pulp and pulp proportioning, the surface layer, the surface lining layer and the bottom layer are all 20% bleached chemical long fiber and 80% bleached chemical short fiber, the core layer is 45% of core layer and 55% low-bulk bleached mechanical pulp, and the quantitative weights of the surface layer, the surface lining layer, the core layer and the bottom layer are respectively 18gsm, 22gsm, 115gsm and 30 gsm. The cardboard 4 is mixed with pulp according to the specific pulp and pulp proportioning range of the application, wherein the proportion and the quantitative amount of the fibers of the surface layer and the surface lining layer are the same as those of the cardboard 3, the fibers are composed of 20% bleaching chemical long fibers and 80% bleaching chemical short fibers, and the quantitative amounts of the surface layer and the surface lining layer are respectively 18gsm and 22 gsm. The core layer was made with 60% high bulk bleached mechanical pulp and 40% bleached chemical staple and the basis weight was increased to 125 gsm. The bottom layer adopts natural color fiber to replace bleached chemical fiber, the fiber proportion is 20 percent of natural color chemical long fiber and 80 percent of natural color chemical short fiber, and the quantitative degree is reduced to 20 gsm.

And respectively dehydrating the surface layer, the surface lining layer, the core layer and the bottom layer to form a fiber layer.

And compounding the four fiber layers one by one through a compounding roller to form the paperboard base paper. Wherein, the surface layer, the surface lining layer, the core layer and the bottom layer are sequentially compounded one by one.

The base paper is subjected to pre-drying, sizing, drying and hard calendering, and a coating is formed on the surface layer of the base paper by coating, so that the paperboard 3 and the paperboard 4 are formed.

Detecting the thickness and the fixed quantity of the paper jam 3 and the paper jam 4, and calculating the ratio of the thickness to the fixed quantity to obtain the bulk of the paper jam 3 of 1.31cm³G, the bulk of the cardboard 4 is 1.45cm³/g。

In this embodiment, the bleaching mechanical pulp and the increase sandwich layer ration of high bulk are used to the sandwich layer, provide the thickness and the intensity performance of card paper, and can show the bulk that improves the card paper, obtain the card paper of high bulk, and the fibre volume that the card paper of production same thickness and intensity need use reduces, can the saving fiber resource. The bottom layer uses the natural color fiber to replace the bleached fiber, so that the environmental pollution can be reduced. The produced paperboard 4 has high bulk, and can meet the performance requirements of strength, stiffness, thickness and the like, and the environmental protection pressure and the production cost of a papermaking enterprise can be reduced.

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.