Preparation process of double-sided high-light composite coated playing card paper

Abstract

The application provides a preparation process of double-sided high-light composite coating playing card paper, and is characterized in that the process comprises the following specific steps: S1, slurry pretreatment: respectively grinding and pretreating NBKP bleached coniferous wood pulp, LBKP bleached broad-leaved wood pulp and BCTMP bleached chemi-thermal pulp, and controlling to obtain various types of slurry with a target freeness; S2, layered slurry preparation: mixing the pretreated various types of slurry in proportion, and respectively preparing a surface layer paper pulp, a core layer paper pulp and a bottom layer paper pulp; through the synergistic cooperation of each process step, on the basis of retaining the core excellent performances of high stiffness, high gloss, anti-transmission of the original playing card paper, anti-transmission, uniform color on the front and back, the application simplifies the traditional complex preparation process, reduces the excessive use of high-end additives and slurry, significantly reduces the comprehensive production cost, matches the market consumption demand of civilian recreational playing cards, and has stable product quality, strong mass production, and practical popularization value.

Description

Technical Field

[0001] This invention relates to the field of playing card base paper production technology, and in particular to a preparation process for double-sided high-gloss composite coated playing card paper. Background Technology

[0002] Playing card base paper is a high-performance paper specifically designed for the manufacture of playing cards. It must meet special requirements such as high stiffness, light-blocking properties, and a smooth, glossy surface. The base paper must have a basis weight of 275-310 g / m². The inner core layer of the pulp is dyed with indigo or black to achieve the light-blocking properties of the playing cards, and there is no significant difference in gloss between the front and back sides.

[0003] From the perspective of domestic playing card consumer market demand, civilian recreational playing cards occupy the absolute mainstream market. Ordinary end consumers have relatively low requirements for the folding resistance of playing cards, and their core demands for the user experience focus on two dimensions: paper stiffness and feel, and high gloss of the paper surface.

[0004] The existing traditional four-layer wire mesh fabrication process is complex and has high raw material and processing costs in order to meet the comprehensive performance requirements of high stiffness, high gloss and light-proof properties of playing card base paper.

[0005] However, considering the consumption characteristics of the mainstream civilian market, it is known that the existing technology has problems of performance redundancy and high production costs, and cannot meet the production needs of mass-market civilian playing cards for low cost and high quality feel. Summary of the Invention

[0006] In view of the above technical problems, the present invention provides a preparation process for double-sided high-gloss composite coated playing card paper that reduces production costs and optimizes the production process while ensuring the excellent stiffness and feel of the playing card base paper and the high gloss of the paper surface.

[0007] This invention provides a process for preparing double-sided high-gloss composite coated playing card paper, characterized by the following specific steps: S1. Pulp pretreatment: NBKP bleached softwood pulp, LBKP bleached hardwood pulp, and BCTMP bleached chemimechanical pulp are ground and pretreated respectively to obtain various pulps with target freeness. S2. Layered pulp preparation: Mix the pretreated pulps in proportion to prepare surface pulp, core pulp and bottom pulp respectively. S3. In-pulp modification treatment: In-pulp additives are added to modify the surface pulp, core pulp and bottom pulp respectively. At the same time, dyes are added to the core pulp for in-pulp dyeing treatment, and the hue L value of the core pulp is controlled to be -13.5 to -14.5. S4. Overlaying and forming: The modified surface pulp, core pulp and bottom pulp are formed into surface layer, core layer and bottom layer respectively, and then overlaid and compounded to form wet paper; S5. Final finishing and forming: The wet paper is sequentially subjected to pressing and dewatering, drying in a drying cylinder, surface sizing, double-sided coating, and calendering to finally obtain low roughness and high gloss playing card base paper.

[0008] The freeness of the NBKP bleached softwood pulp is 370±20 CSF, the freeness of the LBKP bleached hardwood pulp is 400±20 CSF, the freeness of the BCTMP bleached mechanical pulp is 340±20 CSF, the freeness of the BCTMP bleached mechanical refined pulp is 200±20 CSF, and the freeness of the BCTMP bleached mechanical refined pulp is 200±20 CSF.

[0009] The amount of additives added to each layer of pulp, based on the corresponding pulp mass, is as follows: Top layer pulp: 5-10 kg / ton of corn cationic starch, 0.2-0.3 kg / ton of filter aid, and 0.2-0.3 kg / ton of retention aid; Core pulp: 10-15 kg / ton of corn cationic starch, 15-25 kg / ton of dry strength agent, 0.3-0.4 kg / ton of filter aid, 0.3-0.4 kg / ton of retention aid, 1.0-1.5 kg / ton of ASA sizing agent, and 4-6 kg / ton of silica sol; Bottom pulp: 5-10 kg / ton of corn cationic starch, 0.2-0.3 kg / ton of filter aid, and 0.2-0.3 kg / ton of retention aid.

[0010] The core pulp is dyed with a purple alkaline dye, and the amount of dye added is 0.2 to 0.3 kg / ton of pulp based on the mass of the core pulp.

[0011] The raw material mass ratios for each layer of pulp are as follows: Top layer pulp: 15±1% NBKP bleached softwood pulp, 85±1% LBKP bleached hardwood pulp; Core pulp: 10±3% LBKP bleached hardwood refined pulp, 15-20% BCTMP bleached chemimechanical refined pulp, and 70-75% BCTMP bleached chemimechanical pulp; Bottom pulp: 15±1% NBKP bleached softwood pulp and 85±1% LBKP bleached hardwood pulp.

[0012] In step S5, the double-sided coating includes a three-step coating on the front side and a two-step coating on the back side. The coating amount for each step is as follows: Front pre-coating: Coating amount 11±1gsm; Front coat: Coating amount 8±1 gsm; Topcoat: Coating amount 13±1gsm; Backside pre-coating: Coating amount 15±1gsm; Backside coating: Coating amount 17±1gsm.

[0013] The solid content and viscosity parameters of the coatings in each coating process are as follows: Front pre-coating: Solid content 67±1%, viscosity 1100±100cps; Front coating: Solid content 67±1%, viscosity 1100±100cps; Topcoat: Solid content 66±1%, viscosity 900±100cps; Backside pre-coating: Solid content 66±1%, viscosity 1100±100cps; Backside coating: Solid content 66±1%, viscosity 1000±100cps.

[0014] In the S5 double-sided coating process, the front and back sides of the paper web are coated. The coatings for each coating process on the front and back sides are formulated in the following proportions by weight: Front pre-coating: 100 parts of grade 65 self-grinding calcium carbonate, 11.5 parts of styrene-butadiene latex, 0.6 parts of sodium carboxymethyl cellulose (CMC), 0.3 parts of OBA hexasulfonic acid, 0.2 parts of lubricant, and 0.4 parts of water-resistant agent; Front intermediate coating: 100 parts of grade 65 self-grinding calcium carbonate, 11.5 parts of styrene-butadiene latex, 0.6 parts of sodium carboxymethyl cellulose (CMC), 0.3 parts of OBA hexasulfonic acid, 0.2 parts of lubricant, and 0.4 parts of water-resistant agent; Topcoat: 75 parts grade 98 self-ground calcium carbonate, 25 parts kaolin, 13 parts styrene-butadiene latex, 0.4 parts sodium carboxymethyl cellulose (CMC), 0.4 parts OBA hexasulfonic acid, 0.3 parts lubricant, 0.4 parts water-resistant agent; Backside pre-coating: 100 parts of grade 65 self-grinding calcium carbonate, 11.5 parts of styrene-butadiene latex, 0.6 parts of sodium carboxymethyl cellulose (CMC), 0.35 parts of OBA hexasulfonic acid, 0.2 parts of lubricant, and 0.4 parts of water-resistant agent; Back coating: 70 parts grade 98 self-ground calcium carbonate, 30 parts kaolin, 13 parts styrene-butadiene latex, 0.4 parts sodium carboxymethyl cellulose (CMC), 0.4 parts OBA hexasulfonic acid, 0.3 parts lubricant, and 0.4 parts water-resistant agent.

[0015] The calendering process includes hard calendering after sizing and soft calendering on both sides after coating; wherein the pressure load of the hard calendering process is 50-70 KN / m, and the pressure load of the soft calendering process on both the front and back sides is 40-60 KN / m. The surface sizing treatment is performed by sizing both sides of the paper web after drying, with sizing amount of 4.5-5.5 gsm on both the front and back sides, and the amount of surface sizing agent added is 3%-5% per ton of starch.

[0016] The beneficial effects of this invention are as follows: 1. This invention pre-treats NBKP, LBKP, BCTMP and other pulps by differentiating the grinding process and controlling the degree of freeness of each pulp system. At the same time, it combines the special pulp ratios for the surface layer, core layer and bottom layer to take into account both the overall structural strength and surface smoothness of the paper.

[0017] Softwood pulp ensures the basic stiffness and structural stability of the paper, hardwood pulp improves the smoothness of the paper surface, and chemimechanical pulp reasonably fills the core structure. Under the premise of meeting the basis weight requirements of playing card base paper, it effectively solves the defects of traditional process paper being too soft and having poor paper surface smoothness. 2. This invention employs a core-layer-specific purple alkaline dyeing process to control the L-value of the core-layer slurry within the range of -13.5 to -14.5. Combined with a composite additive system including core-layer silica sol and ASA sizing agent, it significantly improves the light-blocking and light-proofing properties of the paper, preventing the problems of light transmission and bottom leakage in playing cards.

[0018] Meanwhile, by using a layered and differentiated pulp additive addition scheme, the core layer is enhanced in terms of dry strength, sizing, retention and filtration, while the surface and bottom layers have simplified additive systems. This ensures the overall strength of the paper and avoids the performance redundancy caused by high proportions of additives throughout the entire process in traditional processes, effectively reducing raw material production costs and adapting to the needs of large-scale mass production. 3. This invention adopts a differentiated coating process of three-stage gradient coating on the front and two-stage composite coating on the back, combined with exclusive solid content, viscosity parameters and coating formulation system for each process. The front is modified by pre-coating, intermediate coating and top coating in layers to gradually reduce the roughness of the paper surface and improve the gloss of the paper surface. The back is coated with thicker coating to ensure the smoothness of the paper surface and the uniformity of gloss on both sides, so that the playing card base paper is smooth and bright on both sides, with no obvious color difference and surface defects, and achieves the finished product effect of low roughness and high gloss color. 4. The present invention, combined with the finishing process of shoe pressing, double-sided uniform sizing, and hard pressing + soft pressing gradient calendering, effectively optimizes the internal fiber bonding state of the paper, eliminates the tightness deviation of the paper surface, and improves the overall flatness and dimensional stability of the paper.

[0019] Sizing treatment enhances the paper's waterproof and moisture-proof properties, while gradient calendering further refines the paper's texture. Without compromising the paper's stiffness, it further reduces surface roughness, ensuring that the finished playing card base paper has a delicate feel and excellent appearance.

[0020] Therefore, through the synergistic cooperation of various process steps, this invention, while retaining the core excellent properties of playing card base paper such as high stiffness, high gloss, light-proofness, and uniform color on both sides, simplifies the traditional complex preparation process, reduces the excessive use of high-end additives and pulps, significantly reduces the overall production cost, matches the market demand for civilian recreational playing cards, and has stable product quality, strong mass production capability, and practical promotion value. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the process flow of the present invention; Figure 2 This is a comparison table between the present invention and the prior art. Detailed Implementation

[0022] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Furthermore, the technical features involved in the different embodiments of this invention described below can be combined with each other as long as they do not conflict with each other. Example 1

[0025] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings.

[0026] S1: Select pulp materials and pretreat LBKP, NBKP, and BCTMP to obtain NBKP bleached softwood pulp with a freeness of 370±20CSF, LBKP bleached hardwood pulp with a freeness of 400±20CSF, BCTMP bleached chemimechanical pulp with a freeness of 340±20CSF, BCTMP bleached chemimechanical fine pulp with a freeness of 200±20CSF, and LBKP bleached hardwood fine pulp with a freeness of 200±20CSF.

[0027] By controlling the degree of freeness of the above five pulps, different water-filtering properties of the pulp can be obtained, which can make the prepared playing card base paper have a certain stiffness and feel and a high gloss of the paper surface.

[0028] S2: Mix the pretreated pulp separately to obtain surface pulp, core pulp and bottom pulp.

[0029] The aforementioned pulp species are mixed in predetermined proportions to produce surface pulp, core pulp, and bottom pulp. In this embodiment, the surface pulp contains 15±1% NBKP bleached softwood pulp and 85±1% LBKP bleached hardwood pulp; the core pulp contains 10±3% LBKP bleached hardwood refined pulp, 15-20% BCTMP bleached chemimechanical refined pulp, and 70-75% BCTMP bleached chemimechanical pulp; and the bottom pulp contains 15±1% NBKP bleached softwood pulp and 85±1% LBKP bleached hardwood pulp.

[0030] By adjusting the types of wood pulp in the surface layer pulp, core layer pulp, and bottom layer pulp, the interlayer bonding of the core layer can be improved and a certain degree of stiffness can be achieved after the paper is formed by wire bonding.

[0031] S3: Add additives to the mixed surface pulp, core pulp and bottom pulp for in-pulp chemical treatment, and add dye to the core pulp for in-pulp dyeing treatment, so that the hue L value of the core pulp is between -13.5 and -14.5.

[0032] After preparing the top layer pulp, core layer pulp, and bottom layer pulp, corresponding additives are added to the three types of pulp for in-pulp chemical treatment, so that each layer has different properties. Furthermore, dyeing treatment is carried out within the core layer pulp to achieve light-proof properties.

[0033] In this step, the additives added to the surface pulp include the following components by weight: 5-10 kg / ton of corn cationic starch, 0.2-0.3 kg / ton of filter aid, and 0.2-0.3 kg / ton of retention aid. The additives added to the core pulp include the following components in the following proportions: corn cationic starch 10-15 kg / ton pulp, dry strength agent 15-25 kg / ton pulp, filter aid 0.3-0.4 kg / ton pulp, retention aid 0.3-0.4 kg / ton pulp, ASA sizing agent 1.0-1.5 kg / ton pulp, and silica sol 4-6 kg / ton pulp; The additives added to the bottom pulp include the following components in the following proportions: 5-10 kg / ton of corn cationic starch, 0.2-0.3 kg / ton of filter aid, and 0.2-0.3 kg / ton of retention aid.

[0034] Meanwhile, purple alkaline dye is added to the core pulp for coloring, giving the core a certain degree of light-proofness. The amount of dye added is 0.2-0.3 kg / ton of pulp based on the mass of the core pulp.

[0035] S4: The prepared surface pulp, core pulp, and bottom pulp are processed to form the surface layer, core layer, and bottom layer, and then laminated to form wet paper.

[0036] By adopting a three-layer wire mesh process, the power cost of paper sheet forming in the wire section is reduced. At the same time, there is no need to switch the wire section forming process. The production of white cardboard / coated cardboard can be converted online without stopping the machine, which reduces the difficulty of production conversion and reduces the loss of production conversion.

[0037] S5: Press and dry the wet paper. The wet paper is pressed and dried in a press dryer to reduce the moisture content of the paper web. In this technical solution, the wet paper is dewatered by shoe pressing and dried by heat transfer in the drying cylinder, and the moisture content is controlled to 7%-8%.

[0038] S6: After drying, the paper web is sized. After the wet paper is dewatered by shoe pressing and drying in the drying cylinder, surface sizing is applied to the front and back of the paper web. The front and back of the paper are sized by film transfer. The sizing agent is cooked cassava starch with a surface sizing agent (mainly styrene-acrylate copolymer) added to the cooked starch. The amount of sizing agent added is 2.5% / ton of starch, and the sizing amount on the front and back is 4.5-5.5gsm. The amount of surface sizing agent used is 3%-5% / ton of starch.

[0039] S7: Apply a coating to the sizing paper web.

[0040] During the coating process, a 3+2 coating method (3 coats on the front and 2 coats on the back) is adopted to further reduce paper surface roughness and improve paper surface smoothness.

[0041] Specifically, in the front coating process, the front side is pre-coated, intermediate coated, and top-coated, with coating amounts of 11±1 gsm for the pre-coat, 8±1 gsm for the intermediate coat, and 13±1 gsm for the top coat. In the back coating process, two coats are applied: a back pre-coat and a back top coat, with a back pre-coat coating amount of 15±1 gsm and a back top coat coating amount of 17±1 gsm.

[0042] The coatings for each coat are differentiated to reduce the roughness of the base paper surface and improve its smoothness. Specifically, in the front pre-coating, the coating includes 100 parts of grade 65 self-ground calcium carbonate, 11.5 parts of styrene-butadiene latex, 0.6 parts of CMC sodium carboxymethyl cellulose, 0.3 parts of OBA hexasulfonic acid, 0.2 parts of lubricant, and 0.4 parts of water-resistant agent; in the front intermediate coating, the coating includes 100 parts of grade 65... The coating consists of: self-ground calcium carbonate, 11.5 parts styrene-butadiene latex, 0.6 parts sodium carboxymethyl cellulose (CMC), 0.3 parts hexasulfonic acid, 0.2 parts lubricant, and 0.4 parts water-resistant agent; the topcoat consists of: 75 parts grade 98 self-ground calcium carbonate, 25 parts kaolin, 13 parts styrene-butadiene latex, 0.4 parts sodium carboxymethyl cellulose (CMC), 0.4 parts hexasulfonic acid (OBA), 0.3 parts lubricant, and 0.4 parts water-resistant agent. In the back pre-coating, the coating comprises 100 parts of grade 65 self-ground calcium carbonate, 11.5 parts of styrene-butadiene latex, 0.6 parts of sodium carboxymethyl cellulose (CMC), 0.35 parts of OBA hexasulfonic acid, 0.2 parts of lubricant, and 0.4 parts of water-resistant agent; in the back topcoat, the coating comprises 70 parts of grade 98 self-ground calcium carbonate, 30 parts of kaolin, 13 parts of styrene-butadiene latex, 0.4 parts of sodium carboxymethyl cellulose (CMC), 0.4 parts of OBA hexasulfonic acid, 0.3 parts of lubricant, and 0.4 parts of water-resistant agent.

[0043] The solid content and viscosity were controlled during the coating process. Specifically, the solid content was 67±1% and the viscosity was 1100±100cps during the front pre-coating; the solid content was 67±1% and the viscosity was 1100±100cps during the front intermediate coating; the solid content was 66±1% and the viscosity was 900±100cps during the front top coating; and the solid content was 66±1% and the viscosity was 900±100cps during the coating on the back of the paper web.

[0044] By controlling the solid content and viscosity, the smoothness of the base paper surface can be improved and the roughness of the base paper surface can be reduced, while also giving the base paper a certain degree of stiffness.

[0045] S8. The paper web undergoes calendering after coating. The paper web is fed into a calender for calendering, and then undergoes hard pressing after sizing and soft pressing after coating. During the hard pressing process, the pressure load is 50-70 KN / m, and during the two soft pressing processes on the front and back sides, the pressure load is 40-60 KN / m.

[0046] This embodiment was implemented on a coated board paper machine with an annual output of 600,000 tons, a paper machine width of 6500 mm, and a design speed of 800 m / min. The fiber raw materials used were: NBKP bleached softwood pulp (brightness 88-90% ISO), LBKP bleached hardwood pulp (brightness 88-90% ISO), and bleached chemimechanical pulp (brightness 71-73% ISO).

[0047] The paper is manufactured using a three-layer wire-flying process, with the following pulp composition percentages for each layer: Top layer: 15±1% NBKP bleached softwood pulp + 85±1% LBKP bleached hardwood pulp; Core layer: 10±3% LBKP bleached hardwood pulp + 15-20% BCTMP bleached chemimechanical pulp + 70-75% BCTMP bleached chemimechanical pulp; Bottom layer: 15±1% NBKP bleached softwood pulp + 85±1% LBKP bleached hardwood pulp. The use of a low proportion of NBKP bleached softwood pulp in the top and bottom layers improves paper surface smoothness. Unlike the traditional four / five-layer wire-flying process used for playing cards, this reduces the power cost of the wire section forming process. It also eliminates the need to switch wire section forming processes, allowing for online conversion to three-layer wire-flying process white cardboard / coated cardboard without downtime, minimizing conversion losses.

[0048] The core layer of the pulp is made using LBKP refined pulp and chemimechanical refined pulp to improve the interlayer bonding strength of the paper; a three-layer overlay process is adopted, which is different from the traditional four-layer / five-layer overlay process of playing cards, reducing the power cost of papermaking and reducing the production loss of paper type transition; a three-coat front and two-coat back process is used to maintain a high gloss paper surface, further improve the paper surface smoothness and reduce the paper surface roughness; the interlayer bonding strength and stiffness are not significantly reduced and remain unchanged to ensure the overall feel of the playing card paper. Example 2

[0049] pass Figure 2 The comparison table clearly shows that this process has the following advantages: 1. The adoption of a three-layer wire mesh process reduces the power cost of paper sheet forming in the wire section. At the same time, it eliminates the need to switch the wire section forming process and allows for online conversion to produce white cardboard / coated cardboard with a three-layer wire mesh process without stopping the machine, thus reducing the difficulty of conversion and minimizing conversion losses.

[0050] 2. The top and bottom layers reduce the NBKP bleached softwood pulp content by 15 percentage points. At the same time, three coats are applied to the front and two coats to the back to reduce paper surface roughness. The front surface roughness is reduced by 33% and the back surface roughness is reduced by 14%, thus improving paper surface smoothness.

[0051] 3. The thickness is increased by 20µm, and the paper bulk increases from 1.04cm³ / g to 1.11cm³ / g, while the paper stiffness remains stable without decreasing; 4. The core layer uses BCTMP refined pulp + LBKP refined pulp to improve interlayer bonding strength, which greatly reduces the amount of reinforcing additives such as cationic starch and dry strength agent in the pulp. The interlayer bonding strength is reduced by only 18%, which reduces production costs and ensures that the playing card paper does not delaminate after multiple bends.

[0052] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. The various components mentioned in this invention are common technologies in the existing field. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A preparation process for double-sided high-gloss composite coated playing card paper, characterized in that... The specific steps include the following: S1. Pulp pretreatment: NBKP bleached softwood pulp, LBKP bleached hardwood pulp, and BCTMP bleached chemimechanical pulp are ground and pretreated respectively to obtain various pulps with target freeness. S2. Layered pulp preparation: Mix the pretreated pulps in proportion to prepare surface pulp, core pulp and bottom pulp respectively. S3. In-pulp modification treatment: In-pulp additives are added to modify the surface pulp, core pulp and bottom pulp respectively. At the same time, dyes are added to the core pulp for in-pulp dyeing treatment, and the hue L value of the core pulp is controlled to be -13.5 to -14.

5. S4. Overlaying and forming: The modified surface pulp, core pulp and bottom pulp are formed into surface layer, core layer and bottom layer respectively, and then overlaid and compounded to form wet paper; S5. Final finishing and forming: The wet paper is sequentially subjected to pressing and dehydration, drying in a drying cylinder, surface sizing, double-sided coating, and calendering to finally obtain low roughness and high gloss playing card base paper.

2. The preparation process of double-sided high-gloss composite coated playing card paper according to claim 1, characterized in that... The freeness of the NBKP bleached softwood pulp is 370±20 CSF, the freeness of the LBKP bleached hardwood pulp is 400±20 CSF, the freeness of the BCTMP bleached mechanical pulp is 340±20 CSF, the freeness of the BCTMP bleached mechanical refined pulp is 200±20 CSF, and the freeness of the BCTMP bleached mechanical refined pulp is 200±20 CSF.

3. The preparation process of double-sided high-gloss composite coated playing card paper according to claim 1, characterized in that... The amount of additives added to each layer of pulp, based on the corresponding pulp mass, is as follows: Surface pulp: 5-10 kg / ton of corn cationic starch, 0.2-0.3 kg / ton of filter aid, and 0.2-0.3 kg / ton of retention aid; Core pulp: 10-15 kg / ton of corn cationic starch, 15-25 kg / ton of dry strength agent, 0.3-0.4 kg / ton of filter aid, 0.3-0.4 kg / ton of retention aid, 1.0-1.5 kg / ton of ASA sizing agent, and 4-6 kg / ton of silica sol; Bottom pulp: 5-10 kg / ton of corn cationic starch, 0.2-0.3 kg / ton of filter aid, and 0.2-0.3 kg / ton of retention aid.

4. The preparation process of double-sided high-gloss composite coated playing card paper according to claim 1, characterized in that... The core pulp is dyed with a purple alkaline dye, and the amount of dye added is 0.2 to 0.3 kg / ton of pulp based on the mass of the core pulp.

5. The preparation process of double-sided high-gloss composite coated playing card paper according to claim 1, characterized in that... The raw material mass ratios for each layer of pulp are as follows: Top layer pulp: 15±1% NBKP bleached softwood pulp, 85±1% LBKP bleached hardwood pulp; Core pulp: 10±3% LBKP bleached hardwood refined pulp, 15-20% BCTMP bleached chemimechanical refined pulp, and 70-75% BCTMP bleached chemimechanical pulp; Bottom pulp: 15±1% NBKP bleached softwood pulp and 85±1% LBKP bleached hardwood pulp.

6. The preparation process of double-sided high-gloss composite coated playing card paper according to claim 1, characterized in that... In step S5, the double-sided coating includes three coats on the front side and two coats on the back side. The coating amount for each step is as follows: Front pre-coating: Coating amount 11±1gsm; Front coat: Coating amount 8±1 gsm; Topcoat: Coating amount 13±1gsm; Backside pre-coating: Coating amount 15±1gsm; Backside coating: Coating amount 17±1gsm.

7. The preparation process of double-sided high-gloss composite coated playing card paper according to claim 6, characterized in that... The solid content and viscosity parameters of the coatings in each coating process are as follows: Front pre-coating: Solid content 67±1%, viscosity 1100±100cps; Front-side intermediate coating: solid content 67±1%, viscosity 1100±100cps; Topcoat: Solid content 66±1%, viscosity 900±100cps; Backside pre-coating: Solid content 66±1%, viscosity 1100±100cps; Backside coating: Solid content 66±1%, viscosity 1000±100cps.

8. The preparation process of double-sided high-gloss composite coated playing card paper according to claim 7, characterized in that... In the S5 double-sided coating process, the front and back sides of the paper web are coated. The coatings for each coating process on the front and back sides are formulated in the following proportions by weight: Front pre-coating: 100 parts of grade 65 self-grinding calcium carbonate, 11.5 parts of styrene-butadiene latex, 0.6 parts of sodium carboxymethyl cellulose (CMC), 0.3 parts of OBA hexasulfonic acid, 0.2 parts of lubricant, and 0.4 parts of water-resistant agent; Front intermediate coating: 100 parts of grade 65 self-grinding calcium carbonate, 11.5 parts of styrene-butadiene latex, 0.6 parts of sodium carboxymethyl cellulose (CMC), 0.3 parts of OBA hexasulfonic acid, 0.2 parts of lubricant, and 0.4 parts of water-resistant agent; Topcoat: 75 parts grade 98 self-ground calcium carbonate, 25 parts kaolin, 13 parts styrene-butadiene latex, 0.4 parts sodium carboxymethyl cellulose (CMC), 0.4 parts OBA hexasulfonic acid, 0.3 parts lubricant, 0.4 parts water-resistant agent; Backside pre-coating: 100 parts of grade 65 self-grinding calcium carbonate, 11.5 parts of styrene-butadiene latex, 0.6 parts of sodium carboxymethyl cellulose (CMC), 0.35 parts of OBA hexasulfonic acid, 0.2 parts of lubricant, and 0.4 parts of water-resistant agent; Back coating: 70 parts grade 98 self-ground calcium carbonate, 30 parts kaolin, 13 parts styrene-butadiene latex, 0.4 parts sodium carboxymethyl cellulose (CMC), 0.4 parts OBA hexasulfonic acid, 0.3 parts lubricant, and 0.4 parts water-resistant agent.

9. The preparation process of double-sided high-gloss composite coated playing card paper according to claim 1, characterized in that... The calendering process includes hard calendering after sizing and soft calendering on both sides after coating; wherein the pressure load of the hard calendering process is 50-70 KN / m, and the pressure load of the soft calendering process on both the front and back sides is 40-60 KN / m.

10. The preparation process of double-sided high-gloss composite coated playing card paper according to claim 1, characterized in that... The surface sizing treatment is performed by sizing both sides of the paper web after drying, with sizing amount of 4.5-5.5 gsm on both the front and back sides, and the amount of surface sizing agent added is 3%-5% per ton of starch.

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