250-700g / m < 2 > halogen-free environment-friendly flame-retardant bobbin paper, tea board paper and grey board paper and preparation method thereof

Abstract

The invention discloses 250-700g / m < 2 > halogen-free environment-friendly flame-retardant bobbin paper, tea paperboard and grey paperboard and a preparation method thereof, and belongs to the technical field of papermaking. The paper pulp fiber is used as a matrix, a phosphorus-nitrogen synergistic flame-retardant system and an inorganic flame retardant are compounded, a cross-linking coupling technology is matched, a special formula is designed according to gram weight gradient, and a paperboard product which is high in flame retardance, high in strength and not prone to layering is prepared through the processes of in-pulp addition flame retardance, surface sizing flame retardance, multi-layer composite forming and gradient pressure squeezing. The oxygen index of the product is not lower than 29%, the flame retardant rating reaches the B1 level, and the product is self-extinguished after being away from fire, free of dripping and smoldering, excellent in physical strength, halogen-free, low-smoke and environment-friendly, and is suitable for the fields of archive supplies, industrial packaging, paper tube production and the like. The formula and the process form closed-loop protection, are difficult to imitate by other manufacturers, have high technical barriers and are suitable for large-scale production.

Description

Flame-retardant yarn tube paper; flame-retardant tea board paper; flame-retardant grey board paper; 250-700g / ㎡; halogen-free flame retardant; gradient formula; multi-layer composite molding Technical Field This invention relates to the field of papermaking technology, specifically to a flame-retardant paperboard with a basis weight of 250-700 g / m² and its preparation method, which is particularly suitable for the industrial production of flame-retardant yarn tube paper, flame-retardant tea board paper, and flame-retardant grey board paper. Background Technology With the increasing demands for fire safety in the archives storage, packaging, and transportation industries, conventional paper tubes, tea board paper, and grey board paper are no longer sufficient due to their flammability. Existing flame-retardant paperboard generally suffers from the following problems: high-grammage products are prone to delamination, flame retardants are easily detached and migrated, physical strength is significantly reduced, formulation versatility is poor, and production processes are simple and easily imitated, making it difficult for companies to form long-term technological barriers.

[0001] To address the aforementioned issues, this invention provides a flame-retardant paperboard with stable flame retardant effect, excellent physical properties, a basis weight range of 250-700 g / m², and dual encryption of process and formula, as well as its preparation method, meeting the industry's high-end flame-retardant needs and forming a core technology for enterprises. Summary of the Invention 3.1 Technical Solution A halogen-free, environmentally friendly, flame-retardant paperboard with a basis weight of 250–700 g / m², based on 100 parts of oven-dry pulp, includes: 100 parts of pulp fiber, 6–19 parts of composite flame retardant, 4–28 parts of inorganic filler, and 1.0–6.5 parts of crosslinking reinforcing agent; the paperboard is divided into three gradient ranges according to basis weight: 250–350 g / m², 400–500 g / m², and 600–700 g / m², with the amount of flame retardant and crosslinking agent increasing with increasing basis weight; it adopts a dual flame-retardant structure of in-pulp flame retardancy + surface sizing, and products with 400 g / m² and above adopt a three-layer composite molding. 3.2 Specific Formula 3.2.1 Flame-retardant yarn tube paper formulation 100 portions of waste paper pulp or wood pulp; Phosphorus-nitrogen composite flame retardant: 8-10 parts for 250-350g, 11-13 parts for 400-500g, and 14-16 parts for 600-700g; Modified aluminum hydroxide: 4-6 parts for 250-350g, 6-8 parts for 400-500g, and 8-10 parts for 600-700g; Carboxymethyl cellulose (CMC) 1.2-2.0 parts; 2.0-3.5 parts of cationic cross-linked starch; 0.10-0.22 parts of PAM retention aid; Crosslinking coupling agent 0.2-0.5 parts; Add an appropriate amount of water. 3.2.2 Flame-retardant tea board paper formulation 100 parts of recycled tea board pulp; Coated intumescent flame retardant: 6-9 parts for 250-350g, 9-12 parts for 400-500g, and 12-15 parts for 600-700g; 2-4 parts zinc borate; 0.5-1.2 parts of nano-silica; Oxidized starch 2.5-4.5 parts; Moisture-proof crosslinking agent: 0.3-0.7 parts; Appropriate amounts of defoamer and retention aid. 3.2.3 Flame-retardant grey board paper formulation 100 parts of waste paper pulp from greyboard; Inorganic-organic composite flame retardant: 10-13 parts for 250-350g, 13-16 parts for 400-500g, and 16-19 parts for 600-700g; 15-28 parts of heavy calcium carbonate; 3.0-5.5 parts of modified starch gum; Interlayer crosslinking agent 0.2-0.6 parts; Appropriate amounts of preservatives and dispersants. 3.3 Flame Retardant Mother Liquor Formulation Type II ammonium polyphosphate, 42 parts; 16 portions of melamine; 11 parts pentaerythritol; 26 parts of aluminum hydroxide were coated. 1.5 parts of silane coupling agent; 2.5 parts of polymeric dispersant; Add deionized water to bring the total to 100 parts.

[0002] Preparation method: High-speed dispersion, sand milling to particle size ≤2μm, pH value adjusted to 7.0-7.4, and stabilized before use. 3.4 Preparation method 1) Pulping: 38-41°SR for 250-350g paperboard, 42-46°SR for 400-700g paperboard; 2) Slurry preparation: Add flame retardant mother liquor, filler, and crosslinking agent in sequence, and stir evenly; 3) Molding: 250-350g uses single-layer molding, 400-700g uses three-layer composite molding, and the core layer has a higher filler content than the surface layer; 4) Pressing: Light paperboard pressure 280-350kPa, medium and heavy paperboard pressure 400-550kPa; 5) Drying: Segmented drying, with the temperature controlled between 115-135℃; 6) Apply flame-retardant adhesive to the surface, calender, and roll up to obtain the finished product. Beneficial effects 1) Weight ranges from 250-700g / ㎡, with a gradient formula design that simultaneously improves flame retardancy and strength, and prevents delamination at high weights; 2) Halogen-free, low-smoke, and environmentally friendly, achieving B1 flame retardancy, oxygen index ≥29%, self-extinguishing upon removal of flame, and no dripping; 3) The flame retardant is cross-linked with the fiber, does not migrate or shed powder, and is stable in use; 4) The formula, process, and mother liquor are all kept secret, making them difficult to imitate or replicate, thus creating a strong technological barrier. 5) Applicable to yarn tube paper, tea board paper, and grey board paper, with strong versatility and suitable for large-scale production. Detailed Implementation Example 1: 450g / ㎡ flame-retardant yarn tube paper The product contains 100 parts oven-dried pulp, 12 parts composite flame retardant, 7 parts modified aluminum hydroxide, 1.8 parts CMC, 2.8 parts cross-linked starch, and 0.3 parts cross-linking coupling agent; freeness 44°SR; three-layer composite molding; pressing pressure 420 kPa; drying temperature 125℃. The product has an oxygen index ≥30%, a flame retardant rating of B1, and high ring crush strength, making it suitable for high-strength paper tubes and archival supports. Example 2: 600g / ㎡ flame-retardant grey board paper The product consists of 100 parts oven-dried pulp, 17 parts composite flame retardant, 24 parts calcium carbonate, 4.8 parts modified starch adhesive, and 0.4 parts interlayer crosslinking agent; it is a three-layer composite molding process, high-pressure pressing, and surface flame-retardant sizing. The product has strong interlayer bonding, high burst strength, and stable flame retardancy, making it suitable for file boxes and heavy-duty packaging back panels.

Claims

1. A halogen-free, environmentally friendly, flame-retardant paperboard with a strength of 250–700 g / m², characterized in that: Based on 100 parts of oven-dry pulp fiber, it contains 6-19 parts of composite flame retardant, 4-28 parts of inorganic filler, and 1.0-6.5 parts of crosslinking reinforcing agent; the paperboard is divided into three gradients according to grammage: 250-350 g / m², 400-500 g / m², and 600-700 g / m². The amount of flame retardant and crosslinking agent increases with the grammage, and a dual flame retardant structure of in-pulp addition and surface sizing is adopted.

2. The flame-retardant paperboard according to claim 1, characterized in that, The composite flame retardant is composed of a phosphorus-nitrogen intumescent flame retardant, coated aluminum hydroxide, zinc borate and silane coupling agent, and is added as a mother liquor prepared by dispersing sand milling.

3. The flame-retardant paperboard according to claim 1, characterized in that, Paperboard with a basis weight of 400-700 g / m² adopts a three-layer composite molding structure, with the core layer having a higher filler content than the surface layer.

4. The flame-retardant paperboard according to claim 1, characterized in that, The paperboard includes flame-retardant yarn tube paper, flame-retardant tea board paper, and flame-retardant grey board paper.

5. A method for preparing flame-retardant paperboard according to any one of claims 1-4, characterized in that, The process includes pulping, pulp preparation, molding, pressing, drying, surface sizing, and calendering steps; the pulp preparation sequence is flame retardant mother liquor, filler, and crosslinking agent; the pulping degree is 38-46°SR, and the drying temperature is 115-135℃.