Paper Coating Slips with Composite Binder for UV Stability
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Solution Overview
Problem
Paper coating slips using styrene-butadiene and styrene-acrylic acid ester copolymers face issues such as UV yellowing, poor bondability, insufficient line porosity, and lack of carrier function for optical brighteners, while styrene-acrylate copolymers have inadequate wet pick resistance and insufficient carrier function.
Innovation Solution
Combining styrene-butadiene or styrene-acrylic acid ester copolymers with vinyl acetate-ethylene copolymers stabilized with polyvinyl alcohol, which enhances binding power and whiteness without compromising the properties of the coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If styrene-butadiene copolymers are used as binders, then binding power is improved, but UV yellowing occurs and carrier function for optical brighteners is lost
Solution Approach 1:
The patent combines styrene-butadiene copolymer with vinyl acetate-ethylene copolymer stabilized with polyvinyl alcohol to create a composite binder system. This composite approach allows the SBR to provide binding power while the VAE/PVA component provides carrier function for optical brighteners and resistance to UV yellowing, thus resolving the contradiction between binding power and UV stability.
Solution Approach 2:
The vinyl acetate-ethylene copolymer stabilized with polyvinyl alcohol serves multiple functions: it acts as a binder, provides carrier function for optical brighteners, and prevents UV yellowing. This multi-functional component compensates for the limitations of styrene-butadiene copolymer, allowing the coating composition to simultaneously achieve binding power and UV stability.
2Strength
If styrene-butadiene copolymers are used as binders, then binding power is improved, but line porosity becomes insufficient
Solution Approach 1:
The patent creates a composite binder system combining styrene-butadiene copolymer with vinyl acetate-ethylene copolymer stabilized with polyvinyl alcohol. This composite approach allows the VAE/PVA component to provide the necessary line porosity for printing while the SBR component maintains binding power, thus resolving the contradiction between binding strength and printability.
3Reliability
If styrene-acrylate copolymers are used as binders, then wet pick resistance is improved, but carrier function for optical brighteners is insufficient
Solution Approach 1:
The patent combines styrene-acrylate copolymer with vinyl acetate-ethylene copolymer stabilized with polyvinyl alcohol to create a composite binder system. The VAE/PVA component specifically provides carrier function for optical brighteners while the styrene-acrylate component maintains wet pick resistance, thus resolving the contradiction between these two properties.
4Illumination intensity
If vinyl acetate-ethylene copolymers are added to improve whiteness, then binding power may be reduced
Solution Approach 1:
The patent uses a composite binder system where vinyl acetate-ethylene copolymer stabilized with polyvinyl alcohol is combined with styrene-butadiene copolymer or styrene-acrylic acid ester copolymer. This composite approach allows the VAE/PVA component to provide whiteness and carrier function while the styrene-containing copolymer maintains binding power, thus resolving the contradiction between whiteness and binding strength.
Data Source
AI summary
The invention provides paper coating slips comprising, as a binder, an aqueous dispersion of a styrene-butadiene copolymer or of a styrene-acrylic ester copolymer, or a mixture of these aqueous dispersions, characterized in that an aqueous dispersion of a polyvinyl alcohol-stabilized vinyl acetate-ethylene copolymer is additionally present in each case.