Block Polymers for Cosmetic Hold and Gloss
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Solution Overview
Problem
Existing block polymers used in cosmetic compositions lack improved hold properties while maintaining gloss, as described in European Patent Application No. 1 411 069 do not effectively combine monomers to enhance both hold and gloss simultaneously.
Innovation Solution
A novel block polymer comprising a first block with a glass transition temperature greater than 20°C, made from acrylate and methacrylate monomers, and a second block with a glass transition temperature of 20°C or less, incorporating acrylic acid, which are incompatible but connected via an intermediate segment, forming a film-forming polymer with improved hold and gloss properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If block polymers are prepared from single acrylate or methacrylate monomers as described in EP 1 411 069, then the polymer structure is simpler, but the hold properties of cosmetic compositions are insufficient
Solution Approach 1:
The patent combines acrylate and methacrylate monomers in the first block, and acrylic acid with low Tg monomers in the second block. This merging of different monomer types creates a copolymer structure that achieves superior hold properties (greater than 80% hold after 24 hours) while maintaining gloss, resolving the contradiction between performance and complexity.
Solution Approach 2:
The invention creates a composite block polymer structure where the first block contains acrylate and methacrylate units, and the second block contains acrylic acid and low Tg monomers. This composite material approach allows the polymer to exhibit both high hold properties and good gloss, overcoming the limitations of single-monomer polymers.
2Reliability
If polymers are made to improve hold properties, then hold increases, but gloss properties deteriorate
Solution Approach 1:
The patent applies local quality by creating distinct blocks with different functions: the first block with acrylate and methacrylate provides hold properties, while the second block with low Tg monomers and acrylic acid maintains flexibility and gloss. This spatial separation of functions allows simultaneous achievement of high hold (greater than 80%) and good gloss properties.
Solution Approach 2:
The invention controls the glass transition temperature parameter by selecting specific monomers with Tg ≤ 20°C for the second block and using acrylic acid (Tg = 106°C) in controlled amounts. This parameter optimization ensures the polymer maintains both hold and gloss, resolving the trade-off between these properties.
3Reliability
If acrylic acid is incorporated into the polymer, then hold properties improve, but the polymer becomes more incompatible with other blocks
Solution Approach 1:
The patent uses an intermediate block containing both acrylate/methacrylate and acrylic acid units to mediate between the incompatible blocks. This intermediary block acts as a compatibilizer, allowing the polar acrylic acid-containing block to connect with the less polar acrylate/methacrylate block, maintaining composition stability while enabling hold improvement through acrylic acid incorporation.
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 novel block polymer enhances the hold of cosmetic compositions while maintaining good gloss, providing a polymer that is water-insoluble and non-elastomeric, with specific monomer proportions and structures that achieve the desired glass transition temperatures and compatibility.
Implementation Method 1
a film-forming polymer with improved hold and gloss properties
Implementation Method 2
one of the blocks has a glass transition temperature of greater than 20° C. ('rigid' block) and the other block has a glass transition temperature of less than or equal to 20° C. ('flexible' block)
Data Source
AI summary
Disclosed herein are novel block polymers comprising at least one first block and at least one second block, wherein the at least one first block comprises at least one acrylate monomer of formula CH2═CH—COOR2 wherein R2 is chosen from C4 to C12 cycloalkyl groups and at least one methacrylate monomer of formula CH2═C(CH3)—COOR′2 wherein R′2 is chosen from C4 to C12 cycloalkyl groups, and the second block comprises at least one acrylic acid monomer and at least one monomer with a glass transition temperature of less than or equal to 20° C. Also disclosed herein is a process for the preparation of such polymers which may be carried out continuously in a single reactor. Finally, further disclosed herein are compositions comprising the novel polymers and processes using the composition for making up and/or caring for keratinous substances or for improving the hold of a cosmetic composition while maintaining its gloss.