Composite Pigment UV Filter Coating for Skin Irritation

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Solution Overview

Problem

Existing cosmetic UV filters, particularly inorganic solid UV filters like TiO2, face challenges with aggregation and poor dispersibility, leading to insufficient UV filtering effects and potential skin irritation.

Innovation Solution

A composite pigment comprising small hollow core particles with a mean size of 100 nm to 1 µm, coated with 50% or more of an inorganic solid UV filter layer, including silicon carbide or titanium oxide, and a large core particle, enhances UV filtering effects while reducing skin irritation by firmly bonding UV filters to the core particles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If inorganic solid UV filters like TiO2 are used to shield UV rays, then UV filtering effect is improved, but dispersibility deteriorates and aggregation occurs

Engineering Contradiction:

ImproveUV filtering effectVSAvoiddispersibility

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent uses composite materials by combining inorganic solid UV filters with organic polymers to form core-shell structured particles. The inorganic core provides UV filtering capability while the organic polymer shell improves dispersibility and prevents aggregation, resolving the contradiction between UV filtering effect and dispersibility

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies a polymer shell around the inorganic UV filter core, creating a flexible coating that prevents direct contact between inorganic particles. This shell structure maintains the UV filtering function while eliminating aggregation issues and improving dispersibility in cosmetic formulations

Inventive Principle:

Principle #30Flexible shells and thin films

2Reliability

If fine particles of inorganic solid UV filters are used, then UV filtering effect is improved, but skin irritation risk increases

Engineering Contradiction:

ImproveUV filtering effectVSAvoidskin irritation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The polymer shell acts as a protective barrier that prevents fine inorganic UV filter particles from directly contacting the skin. This eliminates the skin irritation risk associated with fine particles while maintaining their superior UV filtering capabilities

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The organic polymer serves as an intermediary substance between the inorganic UV filter particles and the skin. It mediates the interaction by providing a safe interface that allows UV protection function while preventing harmful direct contact with skin tissues

Inventive Principle:

Principle #24Intermediary (Mediator)

3Stability of the object's composition

If inorganic solid UV filters are coated on large core particles, then dispersibility is improved, but UV filtering effect becomes insufficient

Engineering Contradiction:

ImprovedispersibilityVSAvoidUV filtering effect

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent changes the particle size parameter by using smaller core particles (5-50 nm inorganic UV filters) compared to conventional large particles. This size reduction enhances UV filtering effect through increased surface area and quantum size effects, while the polymer shell maintains dispersibility

Inventive Principle:

Principle #35Parameter changes

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 composite pigment provides improved UV filtering capabilities and safer skin application by preventing free UV filter particles from contacting the skin, offering better cosmetic effects such as smoother application and reduced friction, along with enhanced UV shielding and color tone.

Implementation Method 1

Many cosmetics include one or more UV filters in order to shield UV rays. In particular, skin cosmetics commonly include inorganic solid UV filters such as fine particles of TiO2 for protecting the skin from UV rays.

Methodology Applied

Scientific EffectUV absorption: Absorption (EM radiation)

Implementation Method 2

wherein 50% or more of the surface of the small hollow core particle is covered with at least one coating layer comprising at least one inorganic solid UV filter

Methodology Applied

Scientific EffectCoating/Deposition: Deposition (physical)

Data Source

PatentEP2872106B2Composite pigment and method for preparing the same

Publication Date: 2023.08.02 LOREAL SA

AI summary

The present invention relates to a composite pigment comprising at least one small hollow core particle and optionally at least one large core particle wherein the surface of the small hollow core particle is at least in part covered with at least one coating layer comprising at least one inorganic solid UV filter, and the surface of the large core particle is optionally at least in part covered with at least one coating layer comprising at least one inorganic solid UV filter and/or at least one coloring pigment. The composite pigment according to the present invention can provide enhanced UV filtering effects and safety, and optionally enhanced coloring effects.