Cosmetic Composition with Acrylic-Styrene Copolymers for Sebum-Resistant Concealing
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Solution Overview
Problem
Existing cosmetic compositions for keratin substances, such as skin and mucous membrane surfaces, particularly eye makeup products like eyeliners, struggle to provide long-lasting concealing effects that resist smudging or fading when in contact with sebum or fingers.
Innovation Solution
A composition comprising at least one pigment, a first copolymer of (meth)acrylic acid monomers, and a second copolymer of styrene or a-methylstyrene, with a weight ratio of the second copolymer to pigment of 1.0 or more, and limited use or absence of non-ionic surfactants, to enhance the cosmetic effects and longevity of the makeup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If conventional cosmetic compositions include non-ionic surfactants as film-forming agents, then the composition can provide initial concealing effects, but the concealing effect fades quickly when in contact with sebum or fingers
Solution Approach 1:
The patent changes the chemical parameters of the film-forming agent by using a specific copolymer composition (acrylonitrile-styrene-acrylic acid copolymer with controlled monomer ratios) instead of conventional non-ionic surfactants. This parameter change results in a polymer film that maintains its concealing properties and resists degradation when contacted by sebum or fingers, thereby achieving long-lasting and reliable concealing effects.
Solution Approach 2:
The patent employs a composite polymer system combining acrylonitrile, styrene, and acrylic acid monomers to create a copolymer with synergistic properties. The acrylonitrile units provide hydrophobicity for sebum resistance, styrene units provide structural stability, and acrylic acid units provide adhesion to the skin surface. This composite material approach resolves the contradiction by creating a film that is simultaneously durable, resistant to fading, and adherent.
2Duration of action of stationary object
If the composition uses a high ratio of second copolymer to pigment, then the long-lasting property is improved, but the formulation complexity increases
Solution Approach 1:
The patent establishes specific parameter ranges for the copolymer-to-pigment ratio (second copolymer amount of 1-40 wt%, pigment amount of 1-30 wt%) and for the monomer composition ratios (acrylonitrile 30-70 parts, styrene 20-50 parts, acrylic acid 5-20 parts). By defining these parameters, the patent simplifies the formulation process while achieving the desired long-lasting effect, resolving the contradiction between performance and complexity.
Solution Approach 2:
The copolymer serves multiple functions simultaneously: it acts as a film-forming agent, a binder for the pigment, a resistance layer against sebum, and an adhesion promoter to the skin. This multi-functionality reduces the need for additional separate ingredients, thereby reducing formulation complexity while maintaining long-lasting performance.
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 composition achieves improved concealing of the original keratin surface color and provides long-lasting makeup effects, even under conditions of sebum and finger contact.
Implementation Method 1
at least one first copolymer of at least two monomers selected from (meth)acrylic acid, esters thereof, and salts thereof; at least one second copolymer of styrene or a-methylstyrene and of at least one monomer selected from (meth)acrylic acid, esters thereof, and salts thereof
Implementation Method 2
which can provide the keratin substance with enhanced or improved cosmetic effects, such as better concealing effect of the original color of the keratin substance, as well as long-lasting makeup effects
Data Source
AI summary
The present invention relates to a composition comprising: (a) at least one pigment; (b) at least one first copolymer of at least two monomers selected from (meth)acrylic acid, esters thereof, and salts thereof; (c) at least one second copolymer of styrene or α-methylstyrene and of at least one monomer selected from (meth)acrylic acid, esters thereof, and salts thereof, wherein the weight ratio of the amount of the (c) second copolymer(s)/the amount of the (a) pigment(s) is 1.0 or more, preferably 1.5 or more, and more preferably 2.0 or more, and the composition comprises at least one non-ionic surfactant in an amount of 0.5% by weight or less, preferably 0.3% by weight or less, and more preferably 0.1% by weight or less, relative to the total weight of the composition, or the composition comprises no non-ionic surfactant. The composition according to the present invention is suitable for a keratin substance such as the skin and the surface of a mucous membrane, and can provide the keratin substance with enhanced or improved cosmetic effects, such as better concealing effects of the original color of the keratin substance, as well as long-lasting makeup effects.