PVC-Free Printing Substrate with Porous Intermediate Layer for Inkjet Wall Coverings
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Solution Overview
Problem
Current inkjet printing technologies face challenges in producing durable and high-quality images on large format substrates such as wall coverings, which require excellent mechanical resistance, image permanence, and fast ink absorption to prevent bleed and coalescence, especially at high printing speeds and with high ink loads.
Innovation Solution
A printing substrate comprising fibers from wooded resources with over 5% fiber fines less than 0.1 mm in length, combined with 10-40 wt% particulate inorganic substances of 0.1-2.0 µm size, and a polymeric substance, forming a composite structure that supports inkjet printing and meets durability standards like ASTM F793 and CCC-W-408A, while being PVC-free and fire-resistant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional substrates are used for large format printing, then printing speed can be maintained, but image durability and mechanical resistance are insufficient
Solution Approach 1:
The patent employs a composite substrate structure consisting of multiple layers including a base layer, a porous intermediate layer, and a coating layer. This multi-layer composite design combines materials with different properties: the base layer provides mechanical strength, the porous intermediate layer enables rapid ink absorption and transmission, and the coating layer ensures image durability and resistance to environmental factors. This composite approach resolves the contradiction by integrating materials that collectively deliver both high printing speed and excellent image permanence.
2Manufacturing precision
If high ink load is applied for high quality printing, then image quality improves, but bleed and coalescence occur
Solution Approach 1:
The patent incorporates a porous intermediate layer with controlled porosity and pore size distribution between the base layer and the coating layer. This porous structure acts as an ink reservoir and transmission pathway, enabling rapid capillary absorption of ink droplets upon impact. The controlled porosity prevents ink from spreading laterally (bleed) while allowing sufficient ink to reach the coating layer for high-quality image formation, thus resolving the contradiction between image quality and bleed prevention.
Solution Approach 2:
The substrate exhibits local quality variations through its multi-layer structure, where each layer has specifically tailored properties for its function. The base layer provides mechanical support, the porous intermediate layer provides rapid ink absorption and directional transport, and the coating layer provides image receptivity and durability. This localized functional differentiation allows the substrate to handle high ink loads effectively without bleed, as each layer performs its specific function optimally.
3Productivity
If fast ink absorption is achieved to prevent bleed, then printing speed improves, but image permanence may be compromised
Solution Approach 1:
The porous intermediate layer serves as an intermediary between the base layer and the coating layer. It rapidly absorbs and transports ink from the impact zone to the coating layer through capillary action, enabling fast printing speed. Simultaneously, it prevents direct contact between excessive ink and the coating layer, avoiding saturation and poor adhesion. The intermediate layer thus mediates the ink flow to ensure both rapid absorption and proper ink deposition for permanent images.
Solution Approach 2:
The multi-layer composite structure ensures that fast ink absorption does not compromise image permanence. The porous intermediate layer's rapid capillary absorption enables high printing speed, while the coating layer's specific composition and adhesion properties ensure image permanence. The composite design allows these seemingly conflicting requirements to be satisfied simultaneously through the coordinated function of different layers.
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 substrate achieves enhanced image quality, mechanical strength, and durability, meeting or exceeding Type-II wall covering standards with fast ink absorption rates, preventing bleed and coalescence, and maintaining image quality under various environmental conditions.
Implementation Method 1
The substrate achieves enhanced image quality, mechanical strength, and durability, meeting or exceeding Type-II wall covering standards with fast ink absorption rates, preventing bleed and coalescence
Data Source
Figure 1~2
AI summary
A printing substrate comprising fibers from wooded resource that have more than 5 % of fines fibers with an average length that is less than 0.1 mm; more than about 10 wt % of, at least, a polymeric substance; and between 0.1 wt % and 40 wt % of particulate inorganic substances having an average particle size between 0.1 and 2.0 m. Also disclosed herein a method for making such printing substrate and a method for producing printed images using said printing substrate.