White cardboard and preparation method thereof

Abstract

The invention provides an ivory board and a preparation method thereof. The preparation method comprises the steps that raw paper is manufactured, the raw paper comprises a surface layer, a core layer and a bottom layer, the surface layer, the core layer and the bottom layer are sequentially arranged in a stacked mode, and the quantification of the bottom layer ranges from 26 g / m < 2 > to 30 g / m < 2 >; coating is conducted on the two sides of the body paper respectively, one back coating cloth is adopted, and the coating weight is 14-16 g / m < 2 >. According to the preparation method of the ivory board, the interlayer bonding strength and the coating strength of the back face of the paper are improved, the back face one-time coating is adopted to meet the back face four-color printing processing technology, the preparation method has the advantages of being simple in technology, low in cost and the like, the back face quality of the ivory board can be greatly improved, and the application prospect is wide. And thus, the application range of the white cardboard is widened.

Description

Technical Field

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

[0002] Ivory board, commonly known as social card, is generally coated 2-3 times on the front and 1 time on the back. It is printed on the front to make packaging boxes, medicine boxes, etc. However, in market applications, four-color printing is used on the back, and some also use the front mounting process to make cards, tags, etc. This product has a frosted texture in terms of printing quality. Therefore, the requirements for the back of the white card corresponding to this production process are relatively high. It must not only meet the printing texture and effect, but also ensure the strength of the back of the paper and the strength of the coating to avoid printing bubbles and white spots caused by coating powder falling. At present, the quality requirements for the back of white cards are relatively low, and the application scope of the production process using four-color printing on the back is small. Therefore, ordinary social cards cannot meet the requirements of four-color printing on the back, and often have problems such as printing bubbles or poor printing texture. Summary of the invention

[0003] A first aspect of an embodiment of the present application provides a method for preparing white cardboard, the method comprising:

[0004] Papermaking base paper, wherein the base paper comprises a surface layer, a core layer and a bottom layer stacked in sequence, and the basis weight of the bottom layer is 26-30 g / m 2 ;

[0005] The base paper is coated on both sides, wherein the back coating is one layer, and the coating amount is 14-16g / m 2 .

[0006] In some optional embodiments, the back coating includes pigment, latex and starch, wherein the pigment is GCC60.

[0007] In some optional embodiments, the mass ratio of the latex to the pigment is 9%-11%.

[0008] In some optional embodiments, the mass ratio of the latex to the pigment is 10±0.1%.

[0009] In some optional embodiments, the mass ratio of the starch to the pigment is 2%-4%.

[0010] In some optional embodiments, the mass ratio of the starch to the pigment is 3±0.1%.

[0011] In some optional embodiments, the step of making base paper further includes applying glue to the bottom layer, and the amount of glue applied is 2.8-3.5 g / m 2 .

[0012] In some optional embodiments, the bottom layer of pulp comprises 5-10% bleached kraft softwood pulp and 90-95% bleached kraft hardwood pulp.

[0013] In a second aspect, an embodiment of the present application provides a white cardboard, which is prepared by the preparation method described in the above embodiment.

[0014] In some optional embodiments, the surface roughness of the back printing of the white cardboard is ≤4.2 um.

[0015] The preparation method of white cardboard provided in the embodiment of the present application improves the interlayer bonding strength and coating strength of the back side of the paper, and adopts a one-step coating on the back side to meet the four-color printing processing technology on the back side. The preparation method has the characteristics of simple process and low cost, and can greatly improve the back side quality of white cardboard, thereby increasing the application range of white cardboard. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 This is a schematic diagram of a process of an embodiment of a method for preparing white cardboard of the present application;

[0018] Figure 2 It is a schematic diagram of the cross-sectional structure of an embodiment of the white cardboard of the present application. DETAILED DESCRIPTION

[0019] The present application is further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present application, but are not intended to limit the scope of the present application. Similarly, the following examples are only some embodiments of the present application rather than all embodiments, and all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0020] The terms "first", "second", and "third" in the embodiments of the present application are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first", "second", and "third" can expressly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the embodiments of the present application, all directional indications (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. The terms "including" and "having" in the embodiments of the present application and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or components inherent to these processes, methods, products, or devices.

[0021] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0022] See also Figure 1 , Figure 1 It is a flow chart of an embodiment of a method for preparing white cardboard of the present application, and the preparation method includes but is not limited to the following steps.

[0023] Step S100, making base paper. Figure 2 , Figure 2 1 is a schematic diagram of the cross-sectional structure of an embodiment of the white cardboard of the present application, wherein the base paper in this embodiment comprises a surface layer 110, a core layer 120 and a bottom layer 130 stacked in sequence. The basis weight of the bottom layer 130 is 26-30 g / m 2 , specifically 26g / m 2 , 26.5g / m 2 , 27g / m 2 , 27.8g / m 2 , 28g / m 2 , 30g / m 2The pulp of the bottom layer 130 includes 5-10% bleached kraft softwood pulp and 90-95% bleached kraft hardwood pulp. The basis weight and pulp material of the surface layer 110 and the core layer 120 will be described in detail in the subsequent specific embodiments.

[0024] In this step, the bottom layer 130 may be coated with glue in an amount of 2.8-3.5 g / m 2 Make the back IGT ≥ 2.3m / s, TV16 (red ink simulation printing test) ≥ 1.5 times (2 times of slight bubbling).

[0025] Please continue reading Figure 1 The method for preparing white cardboard in this embodiment further includes step S200 of coating on both sides of the base paper.

[0026] In step S200, the back coating is applied in one pass, and the coating amount is 14-16 g / m 2 The specific coating amount can be 14g / m 2 , 14.2g / m 2 , 14.5g / m 2 , 15g / m 2 , 15.6g / m 2 and 16g / m 2 Please continue to refer to Figure 2 , Figure 2 The reference numeral 210 indicates a back coating layer; the reference numerals 221, 222 and 223 indicate a front pre-coating layer, a front mid-coating layer and a front top coating layer, respectively.

[0027] Optionally, the back coating in this embodiment includes pigment, latex and starch, wherein the pigment is GCC60, and the back coating in this embodiment may include 100% GCC60. The mass ratio of latex to pigment is 9%-11%, and in some embodiments may be 10±0.1%. The mass ratio of starch to pigment is 2%-4%, and in some embodiments may be 3±0.1%.

[0028] In a specific embodiment, the coating formulations for back coating are compared as follows.

[0029] Main components of coating formulation Original recipe New formula Pigment (GCC60) 100％ 100％ Latex (for pigment) 6％ 10％ Coating starch (for pigments) 5％ 3％

[0030] Please refer to the table below, which is a parameter comparison of several specific embodiments of the white cardboard of the present application.

[0031]

[0032]

[0033] The preparation method in the embodiment of the present application has the following characteristics: 1. The back side is coated in one layer and has a high coating amount (14-16g / m 2 ), and the pigment uses GCC60 calcium carbonate, which can better cover the uneven surface of the base paper fiber than GCC93 calcium carbonate, making the four-color printing effect more exquisite; multi-color printing on the back will cause the coating to be wetting and back-pulled by the ink many times, and the strength of the original formula coating is easy to fall off. The new formula increases the number (proportion) of latex and reduces the number (proportion) of coating starch in order to enhance the bonding strength between the coating and the surface of the base paper fiber, and also enhances the bonding strength of the coating itself, making it less likely to fall off and powder, and can also appropriately reduce the speed of ink absorption.

[0034] 2. The amount of glue applied on the back is controlled at 2.8-3.5g / m 2 , so that the back side IGT ≥ 2.3m / s, TV16 (red ink simulation printing test) ≥ 1.5 times (2 times of slight bubbling).

[0035] 3. The bulk thickness of the white cardboard is 1.3-1.7cm 3 / g, the surface roughness of the back printing of white cardboard is ≤4.2um.

[0036] Among them, the base layer 130 is controlled at 26-30g / m 2 NBKP (bleached sulphate softwood pulp) accounts for 5-10% and the rest is LBKP (bleached sulphate hardwood pulp); the back coating amount is controlled at 14-16g / m 2 ; The quantitative requirement of the bottom layer 130 is mainly to cover the color and flatness of the core layer, because the core layer of the social card has a high proportion of mechanical pulp (generally 50-80%), the fiber is coarse and short, the whiteness is low, and the flatness of the paper layer is poor. If the quantitative amount of the bottom layer is insufficient, the defects of the core layer cannot be covered, and the required PPS (Printing Surface Roughness) cannot be achieved, which affects the printing effect. At the same time, the quantitative amount of the bottom layer is insufficient, which will also cause the back of the social card to fold and burst when the box is folded; if the quantitative amount of the bottom layer is too high, the cost will increase significantly, the moisture of the core layer will be relatively difficult to come out, and it is not easy to filter water and dry, requiring stronger dehydration and drying capabilities. At the same time, the quantitative amount of the bottom layer is too high, which will also cause the side paste performance of the social card to deteriorate when it is made into a box, and the bottom layer cannot be torn. The control of the coating amount mainly modifies the back of the base paper to ensure the printing effect; if the coating amount is too low, the required PPS cannot be achieved, which affects the printing effect. If the coating is too high, the strength of the coating is poor, which is easy to cause folding and powdering. If the process conditions permit, hard calendering is preferred, with a line pressure of 15-35KN / m and a temperature of 150-200℃, which is beneficial to the control of PPS on the back of the base paper.

[0037] Please refer to the table below, which is a parameter comparison of several specific embodiments of the white cardboard of the present application.

[0038]

[0039]

[0040] Among them, according to Example 1 and Example 2, it can be explained that increasing the back quantitative (bottom quantitative) is beneficial to the printing effect. Example 5 and Example 6 can illustrate that with the increase of the back quantitative and the coating amount, the risk of ink explosion increases, the printing effect becomes worse accordingly, and the box-sticking test effect also becomes worse. Therefore, each parameter index can only have the desired target effect within the range specified in this application.

[0041] The preparation method of white cardboard in the embodiment of the present application has the following characteristics: 1. The coating amount of the back side is 14-16g / m 2 , the pigments in the coating formula are all GCC60 calcium carbonate, the proportion of latex is increased from 6% to 10%. The proportion of starch is reduced from 5% to 3% to improve the bonding strength between the coating and the surface of the base paper fiber; 2. The amount of sizing on the back is controlled at 2.8-3.5g / m 2 ; Make the back side IGT of the social card paper ≥2.3m / s, TV16 (red ink simulation printing test) ≥1.5 times (less than 3 small bubbles in 2 times), so that the ordinary white card can get a coating on the back side and meet the requirements of four-color printing, with a frosted texture after printing. 3. The back side quantitative control 26-30g / m 2 (NBKP ratio 5-10%), the back pps is controlled ≤4.2um, ensuring processing and printing performance. The preparation method of white cardboard in the embodiment of the present application is simpler than the solution of double coating or multiple coating on the back, and can be produced when the number of coating heads on the paper machine is insufficient, which can improve the quality of social cardboard.

[0042] The preparation method of white cardboard in the embodiment of the present application optimizes the coating formula of the one-time coating on the back of the white card to improve the coating strength; increases the amount of glue applied on the back surface, enhances the bonding strength between the bottom layer and the core layer of the paperboard, and makes the quality indicators IGT and TV16 of the back of the paper meet the specified standards, meets the requirements of 12,000 sheets / minute four-color printing without blistering, fixes the back quantitative and coating amount range, controls the PPS of the back, and ensures the effect of four-color printing on the back; from the above three aspects, the back of the ordinary white card is coated once and meets the requirements of four-color printing.

[0043] The preparation method of white cardboard provided in the embodiment of the present application improves the interlayer bonding strength and coating strength of the back side of the paper, and adopts a one-step coating on the back side to meet the four-color printing processing technology on the back side. The preparation method has the characteristics of simple process and low cost, and can greatly improve the back side quality of white cardboard, thereby increasing the application range of white cardboard.

[0044] The above descriptions are only some embodiments of the present application, and do not limit the protection scope of the present application. Any equivalent device or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing white cardboard, characterized in that: The preparation method comprises: Papermaking base paper, wherein the base paper comprises a surface layer, a core layer and a bottom layer stacked in sequence, and the basis weight of the bottom layer is 26-30 g / m 2 ; The base paper is coated on both sides, wherein the back coating is one layer, and the coating amount is 14-16g / m 2 .

2. The preparation method according to claim 1, characterized in that: The back coating comprises pigment, latex and starch, wherein the pigment is GCC60.

3. The preparation method according to claim 2, characterized in that: The mass ratio of the latex to the pigment is 9%-11%.

4. The preparation method according to claim 3, characterized in that: The mass ratio of the latex to the pigment is 10±0.1%.

5. The preparation method according to claim 3, characterized in that: The mass ratio of the starch to the pigment is 2%-4%.

6. The preparation method according to claim 5, characterized in that: The mass ratio of the starch to the pigment is 3±0.1%.

7. The preparation method according to claim 1, characterized in that: The step of making base paper also includes applying glue to the bottom layer, and the amount of glue applied is 2.8-3.5g / m 2 .

8. The preparation method according to claim 1, characterized in that: The bottom layer of pulp comprises 5-10% bleached kraft softwood pulp and 90-95% bleached kraft hardwood pulp.

9. A white cardboard, characterized in that: The white cardboard is prepared by the preparation method described in any one of claims 1 to 8.

10. The white cardboard according to claim 9, characterized in that: The back printing surface roughness of the white card paper is ≤4.2um.

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