Varnish Layer Gloss Control via Segmented UV Curing
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Solution Overview
Problem
PVC-based surface coverings lack mechanical, chemical, and gas barrier properties, and struggle with VOC emissions, gloss control, and the indentation-acoustic compromise, while existing solutions either compromise on performance or increase production costs.
Innovation Solution
A method involving a varnish composition of polyester acrylate resin, polyester polyol resin, reactive thinner, and photo-initiator applied to PVC-based surfaces, with partial curing using monochromatic radiation and further curing with ultraviolet radiation to form a varnish layer with controlled thickness and gloss, incorporating additives for improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick varnish layer (higher than 20 μm) is applied to provide good protection in aggressive environments, then mechanical and chemical resistance is improved, but production cost increases and brittleness increases
Solution Approach 1:
The patent applies a two-stage curing process with different UV wavelengths: first stage uses 172 nm monochromatic radiation to cure the top layer, second stage uses broader UV spectrum (200-320 nm) to cure the remaining thickness. This parameter change in curing methodology allows achieving adequate protection with reduced varnish thickness (5-15 μm), thereby reducing brittleness and production costs while maintaining mechanical and chemical resistance
Solution Approach 2:
The curing process is segmented into two distinct stages with different radiation characteristics. The first stage targets only the surface layer with monochromatic 172 nm radiation, while the second stage addresses the bulk material with broader UV spectrum. This segmentation enables optimized curing at different depths, allowing reduced overall thickness while maintaining protective functionality
2Illumination intensity
If a matting agent (mainly silica powder) is added to achieve very low gloss (1 to 5 at 60°), then aesthetic appearance is improved, but mechanical properties of the varnish layer decrease
Solution Approach 1:
The patent modifies the curing parameters by using monochromatic 172 nm radiation in the first stage, which has very high curing speed. This parameter change in the curing process enables achieving the desired low gloss effect with reduced matting agent content, thereby preserving the mechanical properties of the varnish layer
3Object-generated harmful factors
If non-volatile materials are used to replace volatile materials to reduce VOC emissions, then environmental performance is improved, but stiffness of the surface covering decreases
Solution Approach 1:
The patent uses a composite varnish composition containing polyester acrylate resin, polyester polyol resin, and reactive thinner in specific proportions. This composite formulation achieves low VOC emissions while maintaining adequate stiffness through the synergistic combination of different material components with complementary properties
4Object-generated harmful factors
If a gas barrier layer (PVOH, EVOH or PVdC) is incorporated to inhibit VOC release, then environmental performance is improved, but mechanical resistance and stain resistance are poor and adhesion to PVC substrate is problematic
Solution Approach 1:
The patent employs a composite varnish composition with polyester acrylate resin, polyester polyol resin, and reactive thinner that inherently provides gas barrier properties against VOC release. This composite approach eliminates the need for separate PVOH/EVOH/PVdC barrier layers, thereby maintaining excellent mechanical resistance, stain resistance, and adhesion to PVC substrate while achieving VOC inhibition
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 PVC-based surface covering with enhanced mechanical, stain, and chemical resistance, effective VOC barrier, controlled gloss, and improved acoustic and indentation performance, balancing economic production with high performance.
Implementation Method 1
partially curing said varnish composition over a thickness of 0.1 to 0.3 μm using a monochromatic radiation having a wavelength comprised between 170 to 174 nm to form a partially cured varnish layer
Implementation Method 2
further curing said varnish composition over the remaining thickness of said varnish layer using a ultraviolet radiation having a wavelength comprised between 200 and 320 nm
Data Source
Figure 1
AI summary
The present invention relates to a surface covering having a controlled gloss, which comprises a varnish layer, said varnish layer comprising a network of a polyester acrylate and a polyester polyol resin, or a polyester resin comprising acrylate and polyol functions, or a polyester acrylate resin with grafted hydroxyl groups. The present invention relates also to a method to produce such a surface covering.