Compacted Outer Packaging Paper for Wet-Strong Tray Wraps
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Solution Overview
Problem
Existing packaging solutions for tray package units face challenges in replacing plastic films with sustainable alternatives that provide good water resistance, wet strength, recyclability, and printability without using coatings or wet-strength agents.
Innovation Solution
A tray package unit outer packaging paper made from an aqueous suspension with long-fibre pulp and sizing agents, compacted on one side to achieve high wet tensile strength, water resistance, and dimensional stability, ensuring good printability and recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coated paper is used to achieve good water tightness and wet strength, then water resistance is improved, but recyclability deteriorates and manufacturing complexity increases
Solution Approach 1:
The paper structure itself provides water resistance through its inherent fibrous network and sizing agents, eliminating the need for external coatings. The paper serves its own protective function without requiring additional layers that would complicate recycling.
Solution Approach 2:
The harmful coating layer is removed from the paper structure. Instead of adding coatings to achieve water resistance, the invention uses uncoated paper with modified composition and structure that naturally resists water while maintaining recyclability.
2Strength
If wet strength agents are added to improve water resistance and wet strength, then mechanical stability in damp conditions is improved, but recyclability deteriorates
Solution Approach 1:
The invention changes the chemical parameters of the paper by using specific sizing agents (alkyl ketene dimer, alkenyl succinic anhydride, rosin sizes) at controlled levels (0.05-2.0 wt.%) to achieve wet strength without cross-linking agents that would hinder recycling. This parameter optimization allows water resistance while maintaining fiber separability for recycling.
Solution Approach 2:
The paper is designed as a disposable packaging material that provides sufficient wet strength for its intended use but is easily recyclable through pulping, accepting that it serves a single purpose then enters the recycling stream without requiring permanent durability enhancements.
3Reliability
If cross-linking of cellulose fibres is used to improve water resistance, then water resistance is improved, but recyclability deteriorates
Solution Approach 1:
The invention changes the chemical approach from cross-linking (which creates permanent bonds) to sizing agent treatment (which provides surface water resistance without fiber fusion). This parameter change in the chemical modification method maintains water resistance while preserving fiber integrity for recycling.
4Ease of manufacture
If paper is used as alternative to plastic films, then recyclability is improved, but water resistance deteriorates
Solution Approach 1:
The invention optimizes paper parameters by controlling fiber composition (long-fibre pulp with specific length), adding sizing agents at precise concentrations, and adjusting paper density to achieve water resistance comparable to plastic films while maintaining the recyclability advantage of paper.
Solution Approach 2:
The paper is formulated as a composite material system combining different fiber types (long-fibre and short-fibre pulp in specific ratios) with sizing agents to achieve properties that neither component alone could provide, specifically the combination of water resistance and recyclability.
5Strength
If compaction is applied to improve water resistance and dimensional stability, then mechanical resistance is improved, but printability may deteriorate
Solution Approach 1:
The invention optimizes compaction parameters (pressure, temperature, duration) to achieve the minimum necessary dimensional stability and water resistance without excessive compaction that would create a surface too smooth or dense for good ink absorption and print quality.
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 paper offers high wet tensile strength, water resistance, and dimensional stability, allowing for efficient packaging and recycling while maintaining high-quality printability, surpassing the properties of plastic films.
Implementation Method 1
The suspension comprises at least one sizing agent selected from a group consisting of alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), rosin sizes or natural sizing agents, or a mixture of sizing agents selected from this group
Implementation Method 2
When reacting with cellulose fibres, cross-links form between the fibres, which lead to increased water resistance of the corresponding paper
Implementation Method 3
at least the first side is compacted with a linear load of 80 kN/m to 500 kN/m
Implementation Method 4
the pulp material comprises a pulp mixture of long-fibre pulp, in particular of long-fibre sulphate pulp, having a length-weighted average fibre length in accordance with ISO 16065-2:2014 of 1.50 mm to 3.0 mm
Data Source
AI summary
A tray package unit outer packaging paper (1), for packaging tray packing units (2), to a method for packaging tray packing units (2) using such a tray package unit outer packaging paper (1), to a method for producing same, and to use of an outer packaging material for packing a tray packaging unit (2). The tray package unit outer packaging paper (1) has a first face (3) and a second face (4) and is made of at least one aqueous suspension (5) comprising a cellulose material (6) and optionally additives (7). The first face (3) is compressed with a linear load of 80 kN/m to 500 kN/m. Additionally, the tray package unit outer packaging paper (1) has a wet tensile strength index, measured according to ISO 3781:2011, in the machine direction of at least 10 Nm/g auf.