Low Viscosity Brake Fluid via Borate-Free Glycol Composition
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Solution Overview
Problem
Existing brake fluids containing borate esters face health hazards due to boric acid's toxicity and risk of gel formation, and borate-free alternatives suffer from high viscosity at low temperatures, failing to meet stringent performance requirements for low viscosity and high boiling points.
Innovation Solution
A functional fluid composition comprising 70-90% alkoxy glycol, with specific ethoxylation degrees and additives, is developed to achieve low viscosity, high boiling points, and resistance to corrosion, while being essentially free from borates and butoxy glycols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If borate esters are used to achieve high boiling points and meet DOT 4/DOT 5.1 criteria, then the wet equilibrium reflux boiling point is very high, but the fluid contains boric acid esters which pose health hazards and risk of gel formation
Solution Approach 1:
The patent removes borate esters from the brake fluid composition entirely, extracting the harmful substance while maintaining the high boiling point performance through alternative glycol and glycol ether components that do not pose health risks or gel formation problems
Solution Approach 2:
The patent changes the chemical composition parameters by using specific ratios of glycols with different chain lengths and glycol ethers, adjusting the molecular structure parameters to achieve high boiling points without borate esters, thereby eliminating health hazards while maintaining thermal performance
2Object-affected harmful factors
If borate-free alternatives are used to eliminate health hazards, then the fluid is free from boric acid esters, but the viscosity at low temperatures becomes too high
Solution Approach 1:
The patent creates a composite fluid composition combining multiple glycol types (ethylene glycol, diethylene glycol, triethylene glycol) and glycol ethers in specific ratios, where each component contributes different properties that collectively achieve low viscosity at low temperatures while maintaining high boiling points and eliminating borate esters
3Stress or pressure
If the fluid viscosity is reduced to meet low temperature performance requirements, then the brake fluid operates satisfactorily at low temperatures, but the boiling point may be compromised
Solution Approach 1:
The patent optimizes the molecular weight distribution and chain length parameters of the glycol and glycol ether components, using a balanced composition of C2-C4 alkyl groups with controlled ethoxylation degrees to simultaneously achieve low viscosity and high boiling point without compromising either property
Data Source
AI summary
This invention relates to a functional fluid, comprising (A) from 70 to 90, preferably 75-87 wt.-% of alkoxy glycol according to formula (I) CH3—O—(CH2—CH2—O)n—H wherein n is a number from 2 to 5, with the proviso that in at least 30 wt.-% of all compounds according to formula (I) n is 3, and that 15 to 65 wt.-% of all compounds according to formula (I) have n=4 or 5, and (B) less than 1.0 wt.-% of alkoxy glycol according to formula (II) R1—O—(CH2—CH2—O)m—H wherein R1 is a C2 to C8 alkyl residue, m is a number from 2 to 6, (C) from 8 to 25, preferably 12-23 wt.-% of at least one compound according to formula (III) H—O—(CH2—CH2—O)k—H wherein k is a number of 2 or higher, with the proviso that in at least 80 wt.-% of all compounds according to formula (III) k is 2 or 3, (D) at least one additive, selected from the group consisting of corrosion inhibitors, alkalinity agents, aging protection agents, defoamers and lubricants, the lubricants being selected from the group consisting of propylene oxide containing alkylene oxide polymers that are optionally substituted with a C1 to C4 alkyl group, triglycerides, castor oil, ricinoleic acid, and ethoxylates of castor oil or ricinoleic acid, and mixtures thereof, the fluid comprising at most 3 wt.-% of an ester between boric acid and a glycol or alkylpolyglycol compound.