Aqueous Coating Composition for Cellulose Packaging
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Solution Overview
Problem
Cellulose-based packaging materials, such as paper and paperboard, often fail to meet the requirements for water and grease resistance, sealability, and recyclability, especially when exposed to hot liquids, due to limitations in existing aqueous coating compositions.
Innovation Solution
An aqueous coating composition comprising polymers derived from alpha-olefins and specific comonomers, combined with calcium carbonate and optionally wax, which enhances hot water barrier properties while maintaining cold water barrier and sealability, and improves processing in heat sealing machines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer film lamination is used to improve water and grease barrier properties, then functionality as packaging material is improved, but recyclability of cellulosic components is complicated
Solution Approach 1:
The patent changes the fundamental parameter of coating composition from organic polymer-based to aqueous polymer-based. This substitution maintains the barrier functionality while enabling recyclability, as the aqueous coating can be more easily separated from cellulosic materials during recycling processes.
Solution Approach 2:
The patent uses composite aqueous polymer formulations containing multiple polymer components (acrylic acid, acrylamide, vinyl alcohol) combined with specific additives. This composite approach achieves the desired barrier properties against water and grease while maintaining compatibility with recyclable cellulosic substrates.
2Reliability
If conventional polymer films are used to provide barrier properties, then hot water resistance is improved, but processability and cost-effectiveness deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the coating from conventional organic polymers to specific aqueous polymers with carboxylic acid groups. This enables hot water resistance through chemical crosslinking mechanisms while maintaining processability in aqueous form and cost-effectiveness through simpler application processes.
Solution Approach 2:
The patent utilizes phase transition mechanisms where the aqueous polymer coating undergoes structural changes upon exposure to hot water or heat treatment. The carboxylic acid groups form crosslinked networks that provide hot water resistance, while the coating remains processable in its aqueous state before application.
3Ease of manufacture
If water-based coating compositions are used to improve recyclability, then recyclability is improved, but hot water barrier properties deteriorate
Solution Approach 1:
The patent changes the functional parameters of the aqueous polymer by incorporating carboxylic acid groups that can form crosslinked networks. This transformation enables the coating to develop hot water barrier properties through chemical crosslinking while maintaining the base formulation as aqueous for recyclability.
Solution Approach 2:
The patent creates a composite aqueous polymer system combining multiple polymer components with specific functional groups. This composite structure provides both the aqueous nature needed for recyclability and the chemical functionality needed for hot water resistance through crosslinking mechanisms.
4Reliability
If coating weight of polymer film is increased to improve barrier properties, then functionality is improved, but recyclability is further complicated
Solution Approach 1:
The patent changes the approach from increasing coating weight to increasing coating functionality through chemical crosslinking. The aqueous polymer coating with carboxylic acid groups forms a crosslinked network that provides enhanced barrier properties at lower coating weights, making recycling more feasible.
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 coating composition significantly reduces hot water absorption, improves stability against hot liquids, and maintains sealability and recyclability, making it suitable for packaging like coffee cups, while being energy-efficient in heat sealing processes.
Implementation Method 1
the addition of the specific amount of calcium carbonate-containing material decreases hot water absorption of a coated paper article
Implementation Method 2
coatings prepared from water-based compositions, often cannot simultaneously provide a paper substrate with all desired properties (e.g. barrier properties against hot and cold water, and oil; sealability; recyclability, etc.)
Implementation Method 3
packaging must be grease or oil resistant
Data Source
AI summary
The present invention relates to an aqueous coating composition. The aqueous coating composition comprises (a) a polymer A comprising units derived from an alpha-olefin and one or more comonomers selected from the group of methacrylates, acrylates, methacrylic acid, acrylic acid, maleates, maleic acid, maleic anhydride, and salts thereof; (b) a polymer B comprising units derived from one or more monomers selected from the group of methacrylates, acrylates, methacrylic acid, acrylic acid, maleates, maleic acid, maleic anhydride, and salts thereof; (c) a calcium carbonate-containing material in an amount in the range of 0.1 to below 20 wt. %, based on the total dry weight of the coating composition; and (d) optionally a wax. Furthermore, the invention relates to a process for preparing an aqueous coating composition according to invention, and to a coated article.