Glass Strand Coating Composition for Mortar Fluidity and Integrity
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Solution Overview
Problem
The existing sizing agents for glass strands have poor integrity, leading to potential splitting or breaking during mixing with mortar, resulting in heterogeneous dispersion and decreased mechanical strength of glass-fiber reinforced concrete (GRC), and the indirect method's alkali elution impairs the sizing agent's function, affecting glass strand integrity and unwinding.
Innovation Solution
A glass strand with a coating containing polyvinyl acetate resin and polyether-based urethane resin, where the polyether-based urethane resin content is between 10% to 90% by mass, and the ether portion is preferably polytetramethylene ether glycol, providing excellent alkaline resistance and integrity, along with optional ethylene-vinyl acetate copolymer, to prevent fluidity reduction and enhance mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional sizing agent is used to integrate glass filaments, then the glass filaments can be integrated into a strand, but the glass strand integrity is poor and the strands may split or break during mixing with mortar
Solution Approach 1:
The patent applies composite materials by combining multiple resin components (polyvinyl acetate resin, polyether-based urethane resin, and ethylene-vinyl acetate copolymer resin) in specific proportions to create a sizing agent that provides both strong integration of glass filaments and maintains strand integrity during mixing. The composite resin system synergistically improves both the binding strength and the flexibility needed to prevent breaking during handling and mixing operations.
2Strength
If the sizing agent contains high content of certain resins to improve integrity, then the glass strand integrity improves, but the fluidity of mortar during molding decreases
Solution Approach 1:
The patent applies parameter changes by carefully controlling the proportions of different resin components in the sizing agent. Specifically, it limits polyvinyl acetate resin to 5-50 parts, polyether-based urethane resin to 45-90 parts, and ethylene-vinyl acetate copolymer resin to 5-40 parts per 100 parts of total resin. These parameter adjustments optimize the balance between strand integrity and mortar fluidity, ensuring the sizing agent provides sufficient binding strength while maintaining workability during molding operations.
3Duration of action of stationary object
If alkali is eluted from glass fibers in the drying step, then the drying process completes, but the sizing agent function is impaired and glass strand integrity decreases
Solution Approach 1:
The patent applies the blessing in disguise principle by selecting resin components that are specifically resistant to alkali elution. The polyether-based urethane resin and ethylene-vinyl acetate copolymer resin chosen in the formulation are chemically resistant to alkali, converting the potentially harmful alkali elution into a non-detrimental process. This allows complete drying to occur while the sizing agent maintains its protective and binding functions throughout the process.
Data Source
Figure 1
AI summary
Provided is a glass strand that, when mixed with mortar, is less likely to decrease the fluidity of the mortar and can effectively increase the mechanical strength of a cementitious material. A glass strand includes: a plurality of glass filaments containing 12% by mass or more ZrO2 and 10% by mass or more R2O (where R represents at least one selected from Li, Na, and K) ; and a coating covering surfaces of the glass filaments, wherein the coating contains polyvinyl acetate resin and polyether-based urethane resin, and wherein a content of the polyether-based urethane resin in the coating is, in solid content ratio, not less than 10% by mass and not more than 90% by mass.