Biodegradable Polyester Waterproofing Polymer for Water-in-Oil Sunscreens
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Solution Overview
Problem
Current sunscreen formulations lack biodegradable, natural polymers that provide high static and water-resistant Sun Protection Factor (SPF) performance, especially in sport sunscreens, as existing synthetic polymers are non-biodegradable and do not meet the required water-resistance standards for high SPF values like 50 or more.
Innovation Solution
A bio-based, biodegradable waterproofing polymer is developed through a non-sequential reaction of polyglycerol, dimer acid, and fatty acid, with a molar ratio of less than 2:1, which imparts high static and water-resistant SPF to water-in-oil sunscreen formulations, using hydrogenated dimer acid to enhance hydrophobicity and hydrophilicity for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synthetic polymers (PVP/olefin copolymers, acrylate copolymers) are used to provide film-forming and water-resistant properties, then high SPF and WR SPF values (50 or more) are achieved, but the polymers are non-biodegradable and harmful to the environment
Solution Approach 1:
The patent changes the chemical composition parameters of the polymer by using polyglycerol (a natural, biodegradable polyol) instead of synthetic polymers like PVP or acrylates. The polyester is synthesized with specific molecular weight ranges (5,000-500,000 Da) and hydrophobicity parameters (contact angle 60-120°) to achieve WR SPF 50+ performance while maintaining biodegradability
Solution Approach 2:
The patent creates a composite polyester structure combining hydrophilic polyglycerol backbone with hydrophobic fatty acid chains (C12-C22) and polyfunctional carboxylic acid groups. This composite structure provides both the water-resistant film-forming properties needed for high WR SPF and the biodegradability of natural polymers
2Object-generated harmful factors
If biodegradable polyesters are used as additives in cosmetics, then environmental friendliness is improved, but water-resistant SPF performance remains low (WR SPF 15 or 30 at most)
Solution Approach 1:
The patent optimizes several critical parameters: molecular weight (5,000-500,000 Da), degree of esterification (30-75%), hydrophobicity (contact angle 60-120°), and the ratio of hydrophobic to hydrophilic groups. These parameter adjustments transform conventional biodegradable polyesters into high-performance water-resistant film formers achieving WR SPF 50+
Solution Approach 2:
The patent develops a composite polyester architecture combining the hydrophilic polyglycerol backbone with hydrophobic fatty acid chains and polyfunctional carboxylic acid crosslinking groups. This composite structure enables the polymer to form water-resistant films while maintaining biodegradability
3Ease of manufacture
If sequential esterification process is used (fatty acid first, then polyfunctional carboxylic acid), then polyesters are obtained as water-in-oil emulsifiers, but the polyesters lack water-resistant film-forming properties for high SPF
Solution Approach 1:
The patent inverts the conventional sequential esterification process by first reacting polyglycerol with polyfunctional carboxylic acids to create a highly functionalized polyol intermediate, then adding hydrophobic fatty acids. This reverse sequence creates pendant carboxylic acid groups that can crosslink to form water-resistant films, a capability absent in conventionally produced polyesters
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 polymer achieves superior water-resistance and SPF performance, maintaining UV absorbers' effectiveness even after water exposure, meeting the goal of SPF 50 and beyond, while being environmentally friendly and suitable for sport use.
Implementation Method 1
Sunscreen formulations contain so-called active materials that either absorb or scatter UV light of specified wavelengths
Implementation Method 2
Sunscreen formulations contain so-called active materials that either absorb or scatter UV light of specified wavelengths
Implementation Method 3
a class of materials, typically polymers, are used to provide film-former and water-resistant properties
Implementation Method 4
using hydrogenated dimer acid to enhance hydrophobicity and hydrophilicity for improved performance
Data Source
Figure 1
AI summary
The present disclosure generally relates to a waterproofing polymer that is a reaction product of the following components: (i) at least one polyglycerol; (ii) at least one dimer acid; and (iii) at least one fatty acid having 8-30 carbon atoms, wherein (iii) and (i) are in a molar ratio of less than 2:1. The components are charged to a reaction vessel and subsequently reacted to produce a polyester polymer having excellent waterproofing properties. The polymers impart high static and water-resistant SPF to water-in-oil sunscreen formulations.