Writing Paper product parameters and manufacturing process description 1、 Core parameters of the product
（1） Basic specifications
1. Size specifications: Supports standardized production and
customized cutting, with conventional mainstream sizes covering multiple usage scenarios
• Regular size: 787mm × 1092mm (can be cut into commonly used format such as 16 open and 32 open, suitable for
Notebook and workbook production)
• Large size: 889mm × 1194mm (suitable for large format writing needs, such as drawing books and engineering record paper)
Customized size: It can be accurately cut according to customer needs (such as irregular sizes, special aspect ratios), with a cutting error controlled within ± 0.3mm, to meet personalized printing scenarios.
2. Weight range: 40g-120g, suitable for different writing and printing needs. The typical application scenarios corresponding to each weight are as follows
40g-60g: Thin writing paper suitable for letter paper and sticky notes, with smooth writing and lightweight paper
70g-80g: Conventional writing paper, widely used for notebooks, workbooks, and office document paper, balancing writing experience and paper stiffness
90g-120g: Thick writing paper, suitable for cover inner pages, cards, high-end notebook cores, with high stiffness and folding resistance
（2） Material and Performance Parameters
3. Raw material composition: High quality wood pulp and auxiliary materials are used to ensure the high-quality characteristics of the paper
• Wood pulp content: ≥ 85% (including bleached coniferous wood pulp accounting for 50% -60% to improve paper strength; bleached broad-leaved wood pulp accounting for 25% -35% to optimize paper smoothness)
• Auxiliary ingredients: Add 0.5% -1% sizing agent (AKD neutral sizing agent), 0.3% -0.6% filler (light calcium carbonate), no fluorescent whitening agent (in accordance with GB 19340-2023 "Determination of Fluorescent Whitening Agents for Paper, Paperboard and Pulp" standard to ensure writing safety)
4. Physical performance: After strict testing, all indicators meet the industry's high standards
• Smoothness: ≥ 30s (measured by Buick smoothness tester, 70g writing paper standard), with low resistance of the
pen tip and no scratching phenomenon during writing
Tensile strength: Longitudinal ≥ 3.5kN/m, transverse ≥ 1.8kN/m (GB/T 12914-2023 "Determination of Tensile Strength of Paper and Paperboard"), paper is not easily torn and has strong durability
• Folding resistance: longitudinal ≥ 15 times, transverse ≥ 5 times (measured by MIT bending resistance tester, 23 ℃, 50% RH environment), not easily broken after repeated folding, suitable for frequent browsing of laptops
• Water absorption: 20-60s (time required for a water absorption height of 30mm using a portable absorption tester), ink is not easily smudged, and writing is clear
5. Appearance quality: Strictly control the surface condition to ensure visual and user experience
Paper cleanliness: no obvious dust, spots, or holes, with ≤ 10 dust points per square meter (dust above 0.2mm ²)
• Color uniformity: whiteness deviation ≤ 2% (measured by ISO whiteness meter, standard whiteness 85% -90%), no significant color difference, and uniform color of the entire batch of paper
Edge regularity: The deviation of the edge of the roll paper is ≤ 1mm/m, the right angle accuracy of the edge of the flat paper is ± 0.5 °, and there are no burrs or curls
（3） Adapt process parameters
1. Printing adaptability: Meet the needs of multiple printing methods and ensure printing effects
• Ink absorption: Ink drying time during printing is 20min-40min (25 ℃, 50% RH environment), with no through printing or overprinting defects, and a printing resolution of ≥ 150 lines/inch
Surface strength: ≥ 1.5m/s (measured by IGT printing adaptability tester), no powder or hair loss during printing, ensuring plate cleanliness and printing quality
• Humidity stability: Moisture content of 6% -8% (GB/T 462-2008 "Determination of moisture content of test samples for paper, paperboard and pulp analysis"), paper is not easily deformed during the printing process, and the printing accuracy deviation is ≤ 0.1mm
2. Binding adaptability: Suitable for various binding processes to ensure firm binding
• Stiffness: Longitudinal ≥ 50mN · m, transverse ≥ 30mN · m (GB/T 22364-2008 "Determination of Static Stiffness of Paper and Paperboard"), the paper is not easily bent during binding, making it easy to cut and bind
• Durability: ≥ 1.2kPa (70g writing paper standard, GB/T 454-2002 "Determination of Paper Durability"), the paper is not easily damaged during the binding process, ensuring the integrity of the binding
2、 Refined production process
（1） Raw material pretreatment stage
1. Wood pulp screening and purification: The original wood pulp is put into a screening equipment, and impurities (such as fiber bundles and dust particles) are removed through a 100 mesh sieve. Then, it is further purified by a slag remover (pressure difference of 0.15MPa-0.2MPa) to ensure that the purity of the wood pulp is ≥ 99.5%, laying the foundation for the high-quality characteristics of the paper.
2. Auxiliary material preparation and mixing: According to the precise ratio (85% wood pulp, 0.8% sizing agent, 0.5% filler, 13.7% other additives), add sizing agent, filler and other auxiliary materials into the mixing tank, and stir at a speed of 300r/min for 20min to 30min at a temperature of 30 ℃ -40 ℃ to form a uniform pulp mixture, ensuring that the auxiliary materials are fully integrated with the wood pulp.
3. Pulp concentration adjustment: Transport the mixed pulp to the concentration adjustment tank, add an appropriate amount of water to adjust the concentration to 3% -5% (adjusted according to the paper weight requirements, low weight paper has a low concentration, and high weight paper has a high concentration), and monitor it in real time through an online concentration detector to ensure that the concentration deviation is ≤ 0.2%.
（2） Pulping and Forming Stage
1. Grinding treatment: A dual disc grinder is used to grind the pulp, controlling the grinding concentration to 4% -6% and the grinding gap to 0.1mm-0.3mm. The grinding strength is adjusted according to the paper performance requirements, so that the fiber length of the pulp is controlled between 0.8mm-1.2mm, and the fiber bonding strength is increased by 30% -40%, enhancing the strength and toughness of the paper.
2. Mesh forming: The ground pulp is transported to the mesh of a long web paper machine, and the pulp is evenly distributed on the mesh. 70% -80% of the moisture is removed by vacuum dehydration (vacuum degree -0.06MPa to -0.08MPa) to form wet paper sheets. The running speed of the mesh is adjusted according to the weight of the paper. The running speed of 40g-60g paper is 800m/min-1000m/min, and the running speed of 90g-120g paper is 500m/min-700m/min, ensuring uniform thickness of the moisture paper.
3. Pressing and dehydration: Wet paper enters the pressing section and is pressed and dehydrated by upper and lower pressing rollers (pressure 150kN/m-200kN/m) to reduce the moisture content of wet paper to 40% -50%. The surface of the press roller is covered with rubber (hardness 70 Shore A) to ensure uniform pressing and avoid indentation and damage to wet paper sheets.
（3） Drying and calendering stage
1. Multi stage drying: Wet paper enters the drying section and undergoes multi-stage drying through 15-20 sets of drying cylinders. The temperature of the drying cylinders gradually increases from the inlet to the outlet (inlet 60 ℃ -70 ℃, outlet 100 ℃ -110 ℃), and hot air assisted drying is used (hot air temperature 110 ℃ -120 ℃, wind speed 2m/s-3m/s) to control the moisture content of the paper at 6% -8%. During the drying process, a tension control system (tension of 200N/m-300N/m) is used to maintain the flatness of the paper and avoid wrinkles and curling.
2. Polishing treatment: After drying, the paper enters the calender machine and is subjected to 3-5 rolls of polishing (the upper roll is a cold hard cast iron roll, and the lower roll is an elastic roll). The polishing pressure is 50kN/m-80kN/m, and the polishing speed matches the speed of the drying section (deviation ≤ 5m/min). The smoothness of the paper is improved by polishing (from 20s to 25s to over 30s), making the paper surface flat and smooth, and improving the writing experience.
（4） Cutting and finished product processing stage
1. Precise slitting: According to customer needs, large rolls of paper are transported to a slitting machine for slitting. The slitting machine adopts a PLC control system and is equipped with a laser positioning device (positioning accuracy ± 0.1mm). The slitting speed is adjusted according to the weight of the paper (40g-60g paper speed 300m/min-400m/min, 90g-120g paper speed 200m/min-300m/min). Real time monitoring of dimensional accuracy during the slitting process ensures that the finished product has a dimensional error of ≤ ± 0.3mm and no burrs or tears on the edges.
2. Sorting and stacking: The cut paper is sorted by an automatic sorting device to ensure that the paper is stacked neatly (stacking deviation ≤ 1mm). According to customer requirements, it is quantitatively packaged (500 or 1000 sheets per package). During the packaging process, moisture-proof packaging paper (moisture content ≤ 5%) is used to wrap the paper, and a plastic film is placed on the outer layer to prevent the paper from getting damp.
3. Finished product quality inspection: Each batch of finished products must pass six quality inspections——
• Size inspection: Randomly select 20 sheets of paper and use a vernier caliper with an accuracy of 0.01mm to check the size, with an error of ≤± 0.3mm;
• Appearance inspection: Check the paper surface under natural light (illumination 500lux-800lux) for obvious dust, spots, and holes, with no more than 10 dust points per square meter;
Performance testing: Randomly select 5 sheets of paper and test their smoothness (≥ 30s), tensile strength (longitudinal ≥ 3.5kN/m, transverse ≥ 1.8kN/m), and flexural strength (longitudinal ≥ 15 times, transverse ≥ 5 times). All indicators must meet the standards;
Moisture content detection: Use the drying method (105 ℃± 2 ℃ to dry to constant weight) to detect the moisture content of the paper, which needs to be controlled at 6% -8%;
• Writing test: Use a fountain pen or neutral pen to write on paper, check the clarity of the handwriting, and ensure there is no smudging or scratching of the paper;
Environmental testing: Each batch is sent for testing to determine the content of fluorescent whitening agents (in compliance with GB 19340-2023 standard) and formaldehyde emissions (≤ 0.1mg/m ³, in compliance with GB 18587-2017 standard).
（5） Storage and transportation stage
1. Storage environment control: Finished paper is stored in a constant temperature and humidity warehouse, with temperature controlled at 20 ℃± 5 ℃ and humidity controlled at 45% ± 5%. It is stacked on pallets (with a height of ≤ 1.5m per pallet) to avoid paper deformation under pressure. Regularly inspect the storage process (once a week) to ensure that the paper is not damp or moldy.
2. Transportation guarantee: Closed trucks are used for transportation, and moisture-proof mats are laid inside the carriages to prevent rainwater and moisture from entering. Adjust the fixing method according to the transportation distance (rope fixation is used for short distance transportation, and pallet and wrapping film fixation is used for long distance transportation), to prevent paper stacking and damage during transportation, and ensure that the product is delivered to the customer in good condition.
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