Method for solving linting and dusting during paperboard printing

Abstract

The invention discloses a method for solving linting and dusting during paperboard printing, and belongs to the technical field of papermaking. Comprising the following detailed steps: a slurry preparation process, surface sizing treatment and a drying and curing process, in the slurry preparation process, various high-quality fiber raw materials are carefully selected and mixed, the proportion of various fibers is accurately controlled according to the expected performance and quality requirements of the paperboard, and meanwhile, a proper amount of auxiliaries are added; and the binding force between the fibers and the strength of the paper are enhanced. The raw material ratio in the paperboard production process is precisely regulated and controlled, the specially-made composite surface sizing agent is adopted for surface treatment, and scientific and reasonable drying and curing processes are matched, so that the problems of linting and powdering of the paperboard in the printing process are effectively solved, and the printing quality and the production efficiency of the paperboard are improved.

Description

Technical Field

[0001] This invention relates to the field of papermaking technology, and more specifically, to a method for solving the problem of lint and dust shedding during paperboard printing. Background Technology

[0002] Cardboard, such as white cardboard and gray-backed white cardboard, is widely used in high-end product packaging, book covers, business cards and other fields. In high-speed printing (especially offset and gravure printing), the surface strength of cardboard is required to be extremely high.

[0003] If the paper surface strength is insufficient, the viscosity of the ink on the printing press will "pull up" the fine fibers or filler particles on the paper surface, resulting in lint and dust. Lint and dust will contaminate the printing plate and blanket, causing white spots and dirt spots on the printed matter, which seriously affects the printing quality; frequent machine shutdowns for cleaning are required, reducing printing efficiency and increasing production costs. Summary of the Invention

[0004] The purpose of this invention is to provide a method for solving the problem of lint and dust shedding in cardboard printing. This method addresses the issue that insufficient paper surface strength and the viscous nature of ink in printing presses can "pull up" fine fibers or filler particles from the paper surface, leading to lint and dust shedding. Lint and dust shedding can contaminate the printing plate and blanket, causing white spots and dirt spots on the printed matter, severely affecting print quality. It also addresses the problems of frequent machine shutdowns for cleaning, reduced printing efficiency, and increased production costs.

[0005] A method for solving the problem of paper jam printing lint and powder shedding includes the following detailed steps: Step 1. Slurry preparation process: A mixed slurry with a specific ratio is provided. The slurry is mainly composed of long fiber chemical slurry, short fiber chemical slurry and functional filler kaolin. The addition ratio of long fiber chemical slurry is controlled between 30% and 50% based on the total weight of the oven-dry slurry, and the addition ratio of short fiber chemical slurry is controlled between 50% and 70%. At the same time, kaolin is a key additive, and its dosage is strictly set to 15% to 25% of the total weight of the oven-dry slurry to ensure the optimization of fiber bonding strength and surface properties. Step 2. Surface sizing treatment: A specially formulated composite surface sizing agent is evenly applied to the surface of the cardboard base paper formed after the previous papermaking processes (such as pulping, forming, pressing, etc.). The composite surface sizing agent is composed of the following parts by weight: 5-10 parts cationic starch, 2-5 parts styrene-acrylate copolymer, 1-3 parts polyvinyl alcohol, and the remainder is 82-92 parts water. Through precise mixing and emulsification, the sizing agent is ensured to have good film-forming properties and permeability. Step 3. Drying and curing process: The cardboard that has been surface-sized is subjected to a systematic drying process. Under appropriate temperature and wind speed conditions, the moisture in the composite surface sizing agent is effectively evaporated, and at the same time, the organic components are promoted to form a uniform, dense and well-bonded functional film on the surface of the cardboard, thereby significantly enhancing the surface strength of the paper and reducing lint and dust shedding during the printing process.

[0006] By employing the above technical solutions, precisely controlling the raw material ratios during the cardboard production process, using a specially formulated composite surface sizing agent for surface treatment, and combining this with a scientifically sound drying and curing process, the problem of lint and powder shedding during the printing process of cardboard is effectively solved, thereby improving the printing quality and production efficiency of cardboard.

[0007] Preferably, the amount of composite surface sizing agent used in step b is controlled to be 1 to 3 grams of oven-dry sizing agent per square meter of cardboard surface. This application range can effectively ensure uniform sizing on the cardboard surface, avoiding insufficient surface strength due to insufficient sizing amount, and preventing cost waste and subsequent processing problems due to excessive sizing amount.

[0008] Through the above technical solution, by precisely controlling the amount of composite surface sizing agent applied, not only is the production cost optimized, but the stability of the cardboard in subsequent printing and processing is also ensured. Furthermore, in the preparation process of the composite surface sizing agent, the order of addition and mixing method of each component are carefully designed to ensure that the performance of the sizing agent reaches the optimal state.

[0009] Preferably, the preparation method of the composite surface sizing agent in step b is as follows: First, cationic starch and polyvinyl alcohol are fully gelatinized in hot water to ensure that they are completely dissolved and form a uniform mixture; then the mixture is cooled to below 50°C to avoid the adverse effects of high temperature on the performance of the subsequently added components; finally, styrene-acrylate copolymer emulsion is slowly added and continuously stirred mechanically or manually until all components are mixed evenly to form a stable composite surface sizing agent.

[0010] Through the above technical solution, by strictly controlling each step in the preparation process of the composite surface sizing agent, such as controlling the gelatinization temperature, setting the cooling temperature, and optimizing the stirring method, it is ensured that the components of the sizing agent can be fully integrated to form a composite surface sizing agent with stable performance and reliable quality, which provides a strong guarantee for subsequent cardboard surface treatment.

[0011] Preferably, the long-fiber chemical pulp is made of softwood pulp, which has longer fibers and can significantly improve the tear strength and folding endurance of the cardboard; the short-fiber chemical pulp is made of one or a combination of two of hardwood pulp or bamboo pulp. Short fibers help improve the surface smoothness and printability of the cardboard, and the reasonable ratio of the two can optimize the overall performance of the finished cardboard.

[0012] Preferably, a wet strength agent and a dry strength agent are additionally added to the pulp in step a; wherein the amount of wet strength agent added is 0.5% to 1.5% of the weight of oven-dry pulp, and this dosage range can effectively enhance the physical strength of the cardboard in a humid environment; the amount of dry strength agent added is 0.3% to 1.0% of the weight of oven-dry pulp, so as to improve the tensile strength and toughness of the cardboard in a dry state.

[0013] Preferably, the wet strength agent is polyamide epichlorohydrin resin, which has good water solubility and crosslinking effect, and can significantly improve the wet strength of paper; the dry strength agent is anionic polyacrylamide, which effectively increases the dry strength of paper by forming hydrogen bonds with fibers.

[0014] Preferably, this cardboard not only possesses excellent physical strength and surface properties, but also exhibits good printability and processing stability, making it suitable for a variety of high-end packaging and printing applications.

[0015] Preferably, its IGT printing surface strength is not less than 150 cm / s. This indicator ensures that the cardboard has sufficient surface abrasion resistance and anti-fraying properties during high-speed printing, which can meet the production requirements of high-quality printing.

[0016] Preferably, the cardstock has a smoothness of 30s or more. This characteristic makes the cardstock surface more delicate, which helps to improve the color reproduction and clarity of printed materials, providing an ideal substrate for high-end printed materials. At the same time, the moisture content of the cardstock is controlled between 6% and 8%. This moisture range ensures the stability of the cardstock during the printing process and avoids printing problems caused by excessive or insufficient moisture, such as paper deformation and misregistration.

[0017] Compared with the prior art, the advantages of this invention are: 1. By precisely controlling the raw material ratio in the cardboard production process, using a special composite surface sizing agent for surface treatment, and combining it with a scientific and reasonable drying and curing process, the problem of lint and powder shedding during the printing process of cardboard is effectively solved, thereby improving the printing quality and production efficiency of cardboard.

[0018] 2. By precisely controlling the amount of composite surface sizing agent applied, not only are production costs optimized, but the stability of the cardboard in subsequent printing processes is also ensured. Furthermore, the order of addition and mixing of each component in the preparation process of the composite surface sizing agent are carefully designed to ensure that the performance of the sizing agent reaches its optimal state.

[0019] 3. By strictly controlling each step in the preparation process of the composite surface sizing agent, such as controlling the gelatinization temperature, setting the cooling temperature, and optimizing the stirring method, we ensure that the components of the sizing agent can be fully integrated to form a composite surface sizing agent with stable performance and reliable quality, which provides a strong guarantee for subsequent cardboard surface treatment. Detailed Implementation

[0020] Example 1: Step 1. Pulp preparation: Mix and break down 40% softwood pulp (long fiber) and 60% hardwood pulp (short fiber), add 20% kaolin, 1.0% polyamide epichlorohydrin resin (wet strength agent) and 0.5% anionic polyacrylamide (dry strength agent) of the total oven-dry pulp. After beating and conditioning, feed the pulp into the wire section of the paper machine for forming and pressing to obtain the cardboard base paper. Step 2. Preparation of composite surface sizing agent: In a reaction vessel, add 90 parts of water, heat to 90°C, add 7 parts of cationic starch and 2 parts of polyvinyl alcohol, and maintain the temperature while stirring and gelatinizing for 30 minutes. Then cool to 40°C, slowly add 3 parts of styrene-acrylate copolymer emulsion, and continue stirring for 30 minutes to obtain a homogeneous composite surface sizing agent; Step 3. Surface Sizing and Drying: In a surface sizing machine, apply the above sizing agent to the front side of the cardboard base paper, controlling the sizing amount to 2 g / m². 2 (Oven dry weight). Subsequently, the sizing cardboard is dried in a drying cylinder at a temperature controlled at 100-120℃ to allow the sizing agent to fully form a film and cure. Step 4. Post-processing: After calendering and winding, a basis weight of 250 g / m is obtained. 2 White cardstock.

[0021] Example 2: Step 1. Pulp preparation: Mix and break down 50% softwood pulp (long fiber) and 50% bamboo pulp (short fiber), add 25% kaolin, 1.5% polyamide epichlorohydrin resin (wet strength agent) and 1.0% anionic polyacrylamide (dry strength agent) of the total oven-dry pulp. After beating and conditioning, feed the pulp into the wire section of the paper machine for forming and pressing to obtain the cardboard base paper. Step 2. Preparation of composite surface sizing agent: In a reaction vessel, add 85 parts of water, heat to 95°C, add 10 parts of cationic starch and 3 parts of polyvinyl alcohol, and maintain the temperature while stirring and gelatinizing for 40 minutes. Then cool to 45°C, slowly add 5 parts of styrene-acrylate copolymer emulsion, and continue stirring for 40 minutes to obtain a homogeneous composite surface sizing agent; Step 3. Surface Sizing and Drying: In a surface sizing machine, apply the above sizing agent to the front side of the cardboard base paper, controlling the sizing amount to 3 g / m². 2 (Oven dry weight). Subsequently, the sizing cardboard is dried in a drying cylinder at a temperature controlled at 110-130℃ to allow the sizing agent to fully form a film and cure. Step 4. Post-processing: After calendering and winding, a basis weight of 300 g / m is obtained. 2 Gray-backed white cardstock.

[0022] Comparative Example 1: Cardboard is produced using a traditional process without the addition of composite surface sizing agents. The specific steps are as follows: 45% softwood pulp (long fiber) and 55% hardwood pulp (short fiber) are mixed and broken down, and 18% kaolin is added to the total oven-dry pulp volume. No wet strength or dry strength agents are added. After beating and conditioning, the pulp is fed into the wire section of a paper machine for forming and pressing to obtain the cardboard base paper. The base paper is then directly dried in a drying cylinder at a temperature controlled at 90-110℃ without surface sizing. After calendering and winding, a basis weight of 220 g / m² is obtained. 2 The cardstock.

[0023] Experimental Analysis: Wax stick method: The surface strength of the cardboard prepared in Example 1, Example 2, and Comparative Example 1 was tested using the wax rod method. Specifically, a wax rod of a specific size was slid across the surface of the cardboard at a constant speed with a certain pressure. The distance the wax rod slid from the point where fiber fraying or tearing began to appear on the surface of the cardboard was recorded. This distance is the indicator of the surface strength of the cardboard; the longer the distance, the higher the surface strength of the cardboard.

[0024] Test results show that the surface strength of the white cardboard prepared in Example 1 reached 160 cm / s, the surface strength of the gray-backed white cardboard prepared in Example 2 was 170 cm / s, while the surface strength of the cardboard prepared using the traditional process in Comparative Example 1 was only 120 cm / s. This indicates that the cardboard prepared by the method of the present invention has a significantly improved surface strength, which can effectively reduce lint and dust shedding during the printing process.

[0025] Tape test: The cardboard prepared in Example 1, Example 2, and Comparative Example 1 were further verified using a tape test. Specifically, a uniformly sized tape was tightly adhered to the surface of the cardboard, and then the tape was quickly peeled off at a constant speed and vertical angle. The extent of fiber shedding from the cardboard surface and the amount of fiber remaining on the tape were observed.

[0026] Test results show that after the white cardboard of Example 1 and the gray-backed white cardboard of Example 2 were peeled off, very few surface fibers were shed, and only trace amounts of fibers remained on the tape. In contrast, the traditional process cardboard of Comparative Example 1 showed significant surface fiber shedding, leaving more fibers on the tape. This result further demonstrates that the cardboard prepared by the method of this invention has superior surface strength and anti-fuzzing properties, effectively solving the problem of lint and dust shedding during the printing process.

[0027] Internal strength bonding test: The specific method involves cutting the cardboard sample into standard sizes and using a professional paper tensile strength tester to stretch the cardboard at a specified stretching speed until it breaks. The maximum tensile force at the point of breakage is recorded as an indicator of the internal fiber bonding strength of the cardboard. This test reflects the bonding strength between fibers. If the internal bonding strength is weak, it is not only easy to shed dust, but more serious "delamination" or "peeling" may also occur during printing. High internal bonding strength is the basis for resisting lint and dust.

[0028] Test results show that the white cardstock of Example 1 and the gray-backed white cardstock of Example 2 both performed excellently in the internal strength bonding test, with their maximum tensile strength values ​​significantly higher than those of the conventionally processed cardstock of Comparative Example 1. This indicates that the cardstock produced by the method of this invention not only has significantly improved surface strength but also exhibits tighter internal fiber bonding, thereby further enhancing the overall physical properties of the cardstock and providing a more reliable guarantee for high-quality printing.

[0029] Experimental Results: The combined results of the wax stick test, tape test, and internal strength bonding test clearly show that the cardboard produced using the method provided by this invention exhibits significant advantages in both surface strength and internal fiber bonding strength. Compared to the cardboard of Comparative Example 1 produced using traditional processes, the cardboard in Examples 1 and 2 shows significant improvements in all test indicators. This not only proves that by precisely controlling the raw material ratio, using a specially formulated composite surface sizing agent, and combining it with a scientifically sound drying and curing process, the problem of lint and powder shedding during the printing process of cardboard can be effectively solved, but also significantly improves the printing quality and production efficiency of the cardboard. Furthermore, these test results provide strong data support for the application of the method of this invention in actual production, further verifying its feasibility and effectiveness.

[0030] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. 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 preferred examples of the present invention and are not intended to limit the present invention. Various changes and modifications can be made to the present invention without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for solving the problem of print show-through and print mottle in paperboard printing, characterized in that The method specifically comprises the following detailed steps: Step 1. Slurry preparation process: a mixed slurry with a specific ratio is provided, which is mainly composed of long-fiber chemical pulp, short-fiber chemical pulp and functional filler kaolin; the total weight of the absolutely dry pulp is taken as the basis for calculation, wherein the addition ratio of long-fiber chemical pulp is controlled between 30% and 50%, the addition ratio of short-fiber chemical pulp is correspondingly controlled between 50% and 70%, and the amount of kaolin as a key additive is strictly set to 15% to 25% of the total weight of the absolutely dry pulp, so as to ensure the optimization of fiber bonding strength and surface performance; Step 2. Surface sizing treatment: a specially prepared composite surface sizing agent is uniformly applied to the surface of the cardboard base paper formed through the previous papermaking process (such as beating, forming, pressing, etc.); the composite surface sizing agent is composed of the following components in weight parts: cationic starch 5-10 parts, styrene-acrylate copolymer 2-5 parts, polyvinyl alcohol 1-3 parts, and the rest is water 82-92 parts; through accurate mixing and emulsification treatment, it is ensured that the sizing agent has good film-forming property and permeability; Step 3. Drying and curing process: the cardboard with completed surface sizing is subjected to systematic drying treatment under appropriate temperature and air speed conditions, so that the water in the composite surface sizing agent is effectively evaporated, and at the same time, the organic components form a uniform, dense and functional film with good bonding force on the surface of the cardboard, thereby significantly enhancing the surface strength of the paper and reducing the phenomenon of linting and dusting during printing.

2. The method of claim 1, wherein, The application amount of the composite surface sizing agent used in step b is controlled to be 1-3 grams of absolutely dry sizing agent per square meter of cardboard surface, which can effectively ensure the uniform sizing of the cardboard surface, avoiding both the insufficient surface strength caused by too little sizing amount and the cost waste and subsequent processing problems caused by too much sizing amount.

3. The method of claim 1, wherein, The preparation method of the composite surface sizing agent in step b is specifically as follows: first, the cationic starch and polyvinyl alcohol are fully gelatinized in hot water to ensure that they are completely dissolved and form a uniform mixture; then the mixture is cooled to below 50℃ to avoid the adverse effects of high temperature on the performance of the subsequent added components; finally, the styrene-acrylate copolymer emulsion is slowly added, and continuous stirring is performed by mechanical or manual means until all the components are uniformly mixed to form a stable composite surface sizing agent.

4. The method of claim 1, wherein, The long-fiber chemical pulp is selected from coniferous wood pulp, which has longer fibers and can significantly improve the tearing strength and folding endurance of the cardboard; the short-fiber chemical pulp is selected from one or a combination of broadleaf wood pulp or bamboo pulp, and the short fibers help to improve the surface smoothness and printing suitability of the cardboard, and the reasonable ratio of the two can optimize the comprehensive performance of the finished cardboard.

5. The method of claim 1, wherein, In the slurry of step a, a wet strength agent and a dry strength agent are additionally added; wherein the addition amount of the wet strength agent is 0.5%-1.5% of the weight of the absolutely dry pulp, which can effectively enhance the physical strength of the cardboard in a wet environment; the addition amount of the dry strength agent is 0.3%-1.0% of the weight of the absolutely dry pulp, so as to improve the tensile strength and toughness of the cardboard in a dry state.

6. The method of claim 5, wherein, The wet strength agent is specifically a polyamide epoxy chloropropane resin, which has good water solubility and cross-linking effect, and can significantly improve the wet strength of the paper; the dry strength agent is an anionic polyacrylamide, which can effectively increase the dry strength performance of the paper by forming hydrogen bonds with the fibers.

7. A cardboard prepared by the method of any one of claims 1-6, which not only has excellent physical strength and surface performance, but also has good printing adaptability and processing stability, and is suitable for various high-end packaging and printing application scenarios.

8. The card paper according to claim 7, characterized in that, The IGT printing surface strength of the cardboard is not less than 150 cm / s, which ensures that the cardboard has sufficient surface wear resistance and anti-picking performance during high-speed printing, and can meet the production requirements of high-quality printing.

9. The cardstock of claim 7, further characterized by The smoothness of the cardboard reaches more than 30s, which makes the surface of the cardboard more delicate, helps to improve the color reproduction and clarity of the printed matter, and provides an ideal substrate for high-end printed matter. At the same time, the moisture content of the cardboard is controlled between 6% and 8%, which not only ensures the stability of the cardboard during printing, but also avoids printing problems caused by excessive or insufficient moisture, such as paper deformation and inaccurate overprinting.