PVC-Coated Polyester Mine Grid Using TCPP for Fire Resistance
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Solution Overview
Problem
Existing fire-resistant PVC-coated grids for underground coal mines face challenges in achieving compliance with stringent fire performance standards like the 'One Kilowatt Burner Flame Test' at acceptable costs, particularly due to the difficulty in formulating PVC plastisols with suitable viscosities and the toxicity of traditional flame retardants like TCEP.
Innovation Solution
A PVC-based flame-retardant coating composition is developed using tris-(2-chloroisopropyl) phosphate (TCPP) as a primary plasticizer, combined with high amounts of inorganic fillers and a secondary plasticizer, applied via dip-coating to achieve a fire-resistant grid that passes the 'One Kilowatt Burner Flame Test' without using organic solvents, thereby reducing costs and toxicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional flame retardants like TCEP are used in PVC-coated grids, then fire resistance is improved, but toxicity increases and REACH compliance is lost
Solution Approach 1:
The patent substitutes TCEP with TCPP, changing the chemical parameter of the flame retardant while maintaining the fire resistance function. This substitution maintains effectiveness in meeting fire standards while eliminating REACH compliance issues and reducing toxicity concerns
Solution Approach 2:
The patent creates a composite PVC plastisol formulation combining TCPP as primary plasticizer with secondary plasticizers and high amounts of inorganic fillers. This composite approach achieves fire resistance without relying on toxic single-substance flame retardants
2Reliability
If high amounts of inorganic fillers are added to PVC plastisol to achieve fire resistance, then fire performance is improved, but viscosity increases making dip-coating difficult
Solution Approach 1:
The patent optimizes the balance between inorganic filler content (145-230 phr) and plasticizer ratios to achieve the target viscosity range (1500-4500 cp). By adjusting these parameters, the formulation maintains both fire performance and processability for dip-coating application
Solution Approach 2:
The patent uses secondary plasticizers as intermediaries to mediate between the high inorganic filler content and the desired viscosity. These secondary plasticizers help disperse and lubricate the filler particles, maintaining flowability despite high filler loads
3Ease of manufacture
If organic solvents are used to dilute plastisols to achieve suitable viscosity, then ease of coating is improved, but fire resistance is reduced
Solution Approach 1:
The patent changes the approach to viscosity control by eliminating organic solvents entirely. Instead, it achieves the required viscosity (1500-4500 cp) through optimized plasticizer-filler ratios and plasticizer selection, thereby maintaining both fire resistance and coating applicability
Solution Approach 2:
The patent replaces expensive and fire-hazardous organic solvents with a water-based plastisol system. This substitution uses inexpensive, non-flammable materials to achieve the same viscosity control function without compromising fire safety
4Reliability
If coating weight is increased to achieve fire resistance, then flame persistence time is reduced, but cost increases
Solution Approach 1:
The patent formulates a composite PVC plastisol with TCPP as primary plasticizer, secondary plasticizers, and high inorganic filler content (145-230 phr). This composite formulation achieves superior fire resistance (mean flame persistence time ≤3 seconds) at lower coating weights compared to conventional formulations
Solution Approach 2:
The patent optimizes the chemical composition parameters of the plastisol, specifically the ratio and types of plasticizers combined with inorganic fillers. This parameter optimization enhances the fire-retardant efficiency of the coating, allowing compliance with MDG 3608 standards at reduced coating weights
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 fire-resistant PVC-coated grid that meets the stringent Australian MDG 3608 standard with a mean flame persistence time of 3 seconds or less, while maintaining low coating weights and avoiding the use of organic solvents, thus ensuring effective fire resistance and compliance at reduced costs.
Implementation Method 1
heating the coated fabric for about 5 to 20 minutes to a temperature comprised between 110 °C and 150 °C so as to effect gelatinization of the PVC plastisol and to form a plasticized PVC coating enveloping the polyester yarns of the mesh fabric
Data Source
AI summary
The invention is drawn to a method of making a fire-resistant mine-grid comprising the following steps: - providing a poly(vinyl chloride) (PVC) plastisol, - providing a polyester yarn mesh fabric, - coating the polyester yarn mesh fabric with the PVC plastisol, - heating the coated fabric for about 5 to 20 minutes, more preferably for about 5 to 15 minutes, to a temperature comprised between 10 °C and 150 °C, so as to effect gelatinization of the PVC plastisol and form a plasticized PVC coating enveloping the polyester yarns of the mesh fabric, wherein the PVC plastisol, comprises (a) a poly(vinyl chloride) base resin, (b) from 60 to 140 phr of a primary plasticizer which is tris-(2-chloro- isopropyl)phosphate (TCPP), (c) from 40 to 140 phr of a secondary plasticizer, (d) from 145 to 230 phr of an inorganic filler.