Paper Laminate Barrier Layer That Resists Fold Cracking
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Solution Overview
Problem
Packaging materials using paper laminates suffer from cracks at sharper folds, leading to reduced barrier performance, particularly in water vapor resistance, which is exacerbated by the use of clay coating layers.
Innovation Solution
A laminate structure comprising a base paper with a gas barrier resin layer containing polyolefin or polyvinyl alcohol-based resins and inorganic pigments, where the inorganic pigment is concentrated in a specific region, and further enhanced with a vapor-deposited inorganic layer and an overcoat layer, eliminating the need for a clay coating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clay coating layer is used to seal and smooth paper, then barrier properties are improved, but cracks occur at sharper folds reducing barrier performance
Solution Approach 1:
The patent changes the material parameters of the coating layer by replacing clay with a polymer composition containing polyvinyl alcohol and polyethylene. This chemical parameter change allows the coating to maintain barrier properties while gaining flexibility to prevent cracking at folds.
Solution Approach 2:
The patent uses a composite material approach by combining polyvinyl alcohol and polyethylene in a specific ratio (1:4 to 4:1 by mass). This composite structure provides both the barrier properties of clay and the flexibility needed to prevent cracking at sharp folds.
2Object-affected harmful factors
If paper is used instead of plastic materials, then environmental friendliness is improved, but water vapor barrier performance deteriorates
Solution Approach 1:
The patent creates a composite structure by laminating a polymer coating layer onto paper. The paper provides environmental friendliness while the polymer coating layer (containing polyvinyl alcohol and polyethylene) provides the necessary water vapor barrier performance.
Solution Approach 2:
The polymer coating layer acts as an intermediary between the paper and the external environment. It allows the paper to maintain its eco-friendly properties while the coating layer provides the barrier function that paper alone cannot achieve.
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 laminate maintains sufficient water vapor barrier performance both initially and after folding, while reducing plastic use and maintaining crease retention properties, thus enhancing recyclability and flexibility.
Implementation Method 1
a vapor-deposited inorganic layer on a surface of the gas barrier resin layer opposite to that facing the base paper
Data Source
AI summary
A laminate including a base paper and a gas barrier resin layer provided directly on the base paper, in which a binder resin contained in the gas barrier resin layer includes at least one selected from the group consisting of polyolefin resins and polyvinyl alcohol-based resins, the gas barrier resin layer contains an inorganic pigment in a first region extending from a surface thereof on the base paper side to 50% of the total thickness of the gas barrier resin layer, and 80% by volume or more of the total amount of the inorganic pigment contained in the gas barrier resin layer is present in the first region.