Polythiourethane Casting Resin Impact Resistance
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Solution Overview
Problem
Current polythiourethane cast resins face challenges in achieving high impact resistance and refractive index without compromising optical properties or increasing specific weight, often requiring expensive or hard-to-find special chemicals and involving multi-stage synthesis processes.
Innovation Solution
A one-stage method for producing polyurethane cast resin by mixing dithiols with specific isocyanates, followed by degassing and hardening, using dithiols like ethane-1,2-dithiol and isophorone diisocyanate to achieve high refractive index and impact resistance without the need for expensive chemicals, while maintaining low specific weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If special isocyanates such as norbornane diisocyanate are used to achieve high refraction index and good thermostability, then optical properties are improved, but manufacturing cost increases and availability decreases
Solution Approach 1:
The patent replaces expensive, commercially unavailable special isocyanates (norbornane diisocyanate) with cheaper, readily available alternatives (isophorone diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, α.α.α′.α′-tetramethyl-xylylene diisocyanate, or xylylene diisocyanate). This substitution maintains the required refraction index (≥1.60) and optical properties while significantly reducing manufacturing cost and improving availability.
2Illumination intensity
If cast resins are optimized for high refraction index, then optical properties are improved, but impact resistance decreases
Solution Approach 1:
The patent achieves the simultaneous optimization of optical properties and impact resistance by changing the chemical composition parameters of the thiol component. Specifically, it uses dithiols with formula (I) HS—[CH2CH2—S]x—CH2CH2—SH (where x=0-5) in a controlled amount (5-50 wt%, especially 5-30 wt%). This compositional parameter change enables the polymer to achieve both high refraction index (≥1.60) and high impact resistance (passing FDA Drop Ball test) without compromising either property.
3Strength
If multi-stage synthesis is used to produce sulfur-containing pre-polymers, then impact resistance and optical properties are improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges multiple synthesis stages into a single-stage process. Instead of first producing sulfur-containing pre-polymers of the oligourea type and then hardening them with amines, polyols or polythiols in separate stages, the invention directly reacts isocyanate component (B) with thiol component (A) containing dithiols of formula (I) in one step to produce the final polythiourethane cast resin. This consolidation maintains high impact resistance and optical properties while significantly reducing manufacturing complexity.
4Illumination intensity
If conventional polythiourethane compositions are used, then optical properties are achieved, but specific weight increases
Solution Approach 1:
The patent changes the molecular structure parameters of the thiol component by using dithiols with formula (I) HS—[CH2CH2—S]x—CH2CH2—SH (x=0-5), which have optimized sulfur content and chain structure. This parameter change enables the cast resin to achieve high refraction index (≥1.60) and good optical properties while maintaining low specific weight (≤1.23 g/cm³), overcoming the conventional trade-off between optical performance and weight.
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 method results in cast resins with refractive index ≥1.60, high impact resistance, and low density ≤1.23 g/cm3, suitable for electronic and optoelectronic components, and optical lenses, without the need for multi-stage synthesis or special chemicals, ensuring good optical and mechanical properties.
Implementation Method 1
Mixing at least one thiol component (A) with at least one isocyanate component (B)... Hardening of the polyurethane polymer
Data Source
AI summary
The invention has as subject matter a method for producing a polyurethane cast resin, wherein the production comprises the steps of mixing at least one thiol component with at least one isocyanate component, degassing of the mixture and hardening of the polyurethane polymer in a one-stage process. Cast resins for electronic or optoelectronic components of for the production of optical lenses are obtained by the method of the invention that have good mechanical properties and very good optical properties at the same time by a suitable combination of polythiols as hardening component with commercially available isocyanates. The addition of special isocyanates is also not very necessary, as is the case for carrying out the method in several stages. The method in accordance with the invention results in an economical, one-stage process in the properties of the cast resin that are necessary for the application range.