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Light Diffusion of Tospearl® Disclosure Number: IPCOM000011624D
Publication Date: 2003-Mar-10
Document File: 10 page(s) / 3M

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The Prior Art Database

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Kenneth S. Wheelock, Ph.D: ATTORNEY [+2]


Tospearl is a line of silicones that are widely used in cosmetics to provide slip, lubricity, soft and powdery skin feel, improved spreadability, as well as matte finish and soft focus or line blurring effects. Tospearls are dense spherical silicones with narrow particle size distributions. They are commercially available in different particle sizes ranging from 2-12 microns. In this study, the soft focus effects of Tospearls were determined by (diffused) transmittance or haze and (scattered) reflectance. A relationship was discovered between Tospearl particle size and soft focus effect. Small particle size Tospearl gives better soft focus and more matte finish than large particle size Tospearl. A similar relationship between Tospearl particle size and soft focus was observed in Tospearl containing emulsions. The GE Optical Material Calculator is a software program that enables one to calculate haze value by entering contributing factors such as particle size, percent load, and particle refractive index. It was used to predict haze values of neat Tospearl particles and Tospearl containing emulsions. The models fit well with measured values for both systems. The GE Optical Material Calculator was further used to predict the level of impact of various factors on soft focus.

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Light Diffusion of Tospearl®

Atchara Thompson

GE Silicones, 260 Hudson River Rd, Waterford, NY 12188

There are three approaches to reducing the appearance of lines and wrinkles on the skin.  One approach is to slow down wrinkle and line formation. Several studies have shown that antioxidants such as ascorbic acid or tocopherol and moisturizers such as squalane or sodium PCA effectively slow the formation of wrinkles and lines.  A second approach is to modify the skin to make wrinkles and lines more shallow.  There are various types of chemical peels, such as glycolic acid, that accomplish this task.   A third approach is to mask existing wrinkles and lines through light diffusion.

The use of light diffusing powders to mask wrinkles and lines has been known for many years.  Talc, titanium dioxide, PMMA and boron nitride are commonly used as light diffusing powders.  Titanium dioxide has excellent hiding power to reduce lines and wrinkles, but it tends to give skin a white look due to its high refractive index or RI (about 2.5-2.6).  Powders of lower refractive indices  (RI 1.4-1.5) are gaining popularity because they give a more natural look with added tactile benefits.  Examples are PMMA, boron nitride and Tospearl.  This paper describes the light diffusing properties of Tospearl.


Chemistry and physical properties

Tospearl (INCI name Polymethylsilsesquioxane) is a silicone microsphere made by the hydrolysis and condensation of methyltrimethoxysilane (1).  It is available in different particle sizes ranging from 2.0 to 12 microns (Table I).  With a controlled manufacturing process, these microspheres show narrow particle size distributions.  In general, Tospearl disperses readily, maintains its shape in various solvents and is highly stable at high temperatures - unlike some organic powders.  Once applied, Tospearl provides high spreadability with uniformity, soft feel, slip and low gloss.  The skin feel has been further described as non-oily, smooth and powdery.  These Tospearl properties have been applied in skin and hair care products.  In skin care, Tospearl can be used in creams, lotions, sunscreens, foundations, lipsticks, eye shadows, mascaras etc.  In hair care, Tospearl can be used to improve the feel and slip of hair fibers.  Examples of hair care applications are conditioners (leave in and rinse off) and styling products (gels, mousses, cuticle coats).

Table 1 Characteristics of Tospearl

Average Particle Size( µm)  Specific Surface area( M2/g)                                           Bulk Density                         Water Content (105°C, 60 min)

Tospearl120A                     2.0                                                                    30                                                                     0.35                                          2% or less

Tospearl130A                     3.0                                      ®..