High Solids Film Coating Composition with HPC and PVP/VA Copolymer
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Solution Overview
Problem
Current high solids coating compositions face challenges in achieving improved gloss, low surface roughness, and faster processing times, often compromising on these attributes when trying to achieve high solids content.
Innovation Solution
A water-based coating composition comprising a blend of poly(N-vinyl-2-pyrrolidone-co-vinyl acetate) copolymer, hydroxypropyl cellulose, polydextrose, and medium chain triglycerides, with optional additives like polyethylene glycol and pigments, which provides enhanced adhesion, smoothness, and color stability, allowing for higher solids content without compromising on processing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional coating polymers like HPMC and PVA are used, then film strength and adhesion are achieved, but the inherent high viscosity limits application at 35% solids and high productivity coatings
Solution Approach 1:
The patent uses a composite polymer system combining HPMC (hydroxypropyl methyl cellulose) with PVP/VA (polyvinylpyrrolidone-vinyl acetate) copolymer. This composite approach allows the formulation to achieve both film strength from HPMC and improved processability at high solids content from PVP/VA, resolving the contradiction between reliability and productivity
Solution Approach 2:
The patent modifies the polymer composition parameters by incorporating specific ratios of HPMC (10-30 wt%), PVP/VA (20-40 wt%), and polydextrose (10-30 wt%), along with plasticizers and surfactants. These parameter changes enable the coating formulation to maintain low viscosity at 35% solids content while preserving film-forming properties
2Productivity
If high solids coatings are applied to achieve faster processing times, then productivity is improved, but the coating finish becomes coarser with reduced gloss and increased surface roughness
Solution Approach 1:
The patent adjusts formulation parameters including polymer molecular weight, solids content (30-40%), plasticizer concentration (5-15 wt%), and surfactant levels. These parameter optimizations enable high-speed coating application while maintaining smooth surface finish and gloss by controlling film formation dynamics
Solution Approach 2:
The patent introduces polydextrose as a film-forming agent and plasticizers (triethyl citrate, polyethylene glycol) as intermediaries that mediate between the high solids content and the desired surface quality. These additives facilitate smooth film formation even at high application speeds by modifying rheology and film consolidation
3Loss of time
If the solids content is increased to reduce processing time, then productivity improves, but adhesion and gloss are compromised
Solution Approach 1:
The patent employs a composite formulation with HPMC providing adhesion, PVP/VA enhancing flexibility and adhesion at high solids, and polydextrose contributing to film integrity. This composite material system maintains reliable adhesion even when solids content is increased to 35% or higher for faster processing
Solution Approach 2:
Plasticizers such as triethyl citrate (5-15 wt%) and polyethylene glycol serve as intermediaries that maintain polymer chain mobility and adhesion properties at high solids content. These additives prevent the coating from becoming too rigid or brittle during fast processing, preserving reliable bonding to the substrate
Data Source
AI summary
The present application provides high solids film coating compositions comprising a water-soluble cellulose ether, hydroxy propyl cellulose (HPC), a poly (N-vinyl pyrrolidone-co-vinyl acetate) copolymer, a film-forming agent based on D-glucose, plasticizer, medium chain triglycerides (MCT) and an anti-tack agent. The invention further provides a process for preparing the above described film coating compositions and method of coating solid substrate with such coating compositions.