Kraft Paper Banderole Composition for Tear-Resistant Loop Packaging
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Solution Overview
Problem
Existing packaging materials, particularly unbleached kraft paper, face challenges in maintaining high tear resistance and elasticity, especially when forming loops or tubes for packaging sharp-edged or heavy items, due to the time required for adhesives to cure or thermoplastics to harden, and the risk of tearing under stress.
Innovation Solution
The packaging material is composed of at least 90% primary pulp with a specific fiber length and refining grade, combined with cationic starch and optional coatings, ensuring high tear resistance and elasticity in both machine and transverse directions, allowing for secure packaging without tearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If plastic films or tapes are used for packaging, then elasticity and tear resistance are improved, but environmental sustainability deteriorates
Solution Approach 1:
The patent changes the physical and chemical parameters of paper packaging by controlling fiber length distribution (80-90% of fibers between 2.0-2.9mm), pulp composition (at least 90% primary pulp), and refining degree (13-20° SR). These parameter changes enable paper to achieve plastic-like elasticity and tear resistance while maintaining biodegradability
Solution Approach 2:
The patent creates a composite paper material combining primary pulp with specific additives including cationic starch (0.5-5.0 kg/t), sizing agents (0.5-2.0 kg/t), and optional biodegradable polymers. This composite structure achieves the mechanical properties of plastic while maintaining the environmental benefits of paper
2Reliability
If adhesive sealing is used to form loops or tubes, then sealing capability is improved, but production time increases due to adhesive curing requirements
Solution Approach 1:
The patent replaces chemical adhesive bonding with mechanical interlocking through fiber entanglement achieved through intensive refining (13-20° SR). The refined fibers create a mat structure where fibers mechanically interlock when the paper is formed into loops or tubes, eliminating the need for adhesive curing time
Solution Approach 2:
The paper material itself provides the sealing function through its refined fiber structure. The fibers naturally interlock and bind when compressed or folded, making the material self-sealing without requiring external adhesives or additional processing steps
3Adaptability or versatility
If paper packaging is stretched to form loops or tubes, then adaptability to packaged goods is improved, but risk of tearing increases
Solution Approach 1:
The patent optimizes the fiber length distribution parameter, ensuring 80-90% of fibers are between 2.0-2.9mm in length. This specific size range provides optimal balance between flexibility for forming loops/tubes and strength to prevent tearing during and after the forming process
Solution Approach 2:
The patent applies preliminary refining treatment (13-20° SR) to the paper before it is formed into loops or tubes. This pre-treatment creates a fiber mat structure with enhanced inter-fiber bonding capacity, so that when the paper is subsequently stretched or formed, the fibers can interlock and distribute stresses uniformly, preventing tear propagation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a packaging material with enhanced tear resistance and elasticity, enabling secure packaging of heavy or sharp-edged items without tearing, even under stress, and allowing for efficient production without the need for lengthy adhesive curing times.
Implementation Method 1
containing, in particular, cationic starch
Data Source
Figure 1a~1d
Figure 2
AI summary
The invention relates to a packaging material (1) consisting of an unbleached kraft paper having a Kappa number according to ISO 302:2015 of between 38 and 60 as a base paper, wherein: - the kraft paper is manufactured from at least 90% primary cellulose and has a grammage according to ISO 536:2019 of between 65 g/m2 and 170 g/m2; - furthermore, the kraft paper contains at least 90% primary cellulose, containing at least 80% cellulose with a length-weighted mean fiber length according to ISO 16065-2:2014 of between 2.0 mm and 2.9 mm, and less than 5% fillers as well as cationic starch and other process aids; - the primary cellulose is present in the form of beaten cellulose, more particularly cellulose beaten with high consistency, having a Schopper-Riegler degree of beating according to ISO 5267-1:1999 of between 13 °SR and 20 °SR; - the packaging material has a strain ratio MD/CD of the kraft paper at break according to ISO 1924-3:2005 of > 1.1, a tear length in the machine direction according to ISO 1924-3:2005 of >10 km, and a tear index in the cross direction of the kraft paper according to ISO 1974:2012 of > 16.0 mN·m2/g; - the kraft paper is optionally coated, at least on one side, with a coating material. The invention also relates to a method for manufacturing the packaging material, to a sleeve produced from the packaging material, and to a use of the packaging material.