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Comparatively Speaking: Complex Esters from Neopentyl Glycol vs. Trimethylol Propane vs. Pentaerythritol

Figures

Tables

  • Table 1. Oleate esters

    Table 1. Oleate esters

    Properties NPG oleate TMP oleate PE oleate
    Appearance at 25°C clear liquid clear liquid clear liquid
    Odor bland bland bland
    Color, Gardner 4 4 2
    Refractive index at 25°C 1.463 1.469 1.472
    Viscosity at 40°C, cst 24 48 64
    Iodine value 80 85 87
    Pour point, C -35 -20 -25

     

  • Table 2. Eructates esters

    Table 2. Eructates esters

    Properties NPG erucate TMP erucate PE erucate
    Appearance at 25°C clear liquid clear liquid clear liquid
    Odor bland bland bland
    Color, Gardner 5 4 3
    Refractive index at 25°C 1.466 1.472 1.475
    Viscosity at 40°C, cst 32 65 90
    Iodine value 93 87 85
    Pour point, C -25 -5 -9

     

  • Table 3. C-20 guerbet acid esters

    Table 3. C-20 guerbet acid esters

    Properties NPG guerbet C-20 TMP guerbet C-20 PE guerbet C-20
    Appearance at 25°C clear liquid clear liquid clear liquid
    Odor mild mild mild
    Color, Gardner 4 4 5
    Refractive index at 25°C 1.453 1.459 1.461
    Viscosity at 40°C, cst 36 73 90
    Iodine value 0.3 0.3 0.4
    Pour point, C <-40 -18 -35

     

  • Table 4. Isostearate esters

    Table 4. Isostearate esters

    Properties TMP isostearate PE isostearate NPG isostearate
    Appearance at 25°C clear liquid clear liquid clear liquid
    Odor mild mild mild
    Color, Gardner 3 2 2
    Specific gravity at 25°C 0.91 0.91 0.91
    Viscosity at 40°C, cst 105 167 45
    Iodine value 3.3 3.0 3.2
    Pour point, C -26 -18 -35

     

By: Anthony J. O'Lenick, Jr., Siltech LLC
Posted: May 20, 2009

Complex esters are an important class of compounds in the personal care market. These include fatty derivatives of neopentyl glycol (NPG), trimethylol propane (TMP) and pentaerythritol (PE). Their structures are given in Figure 1, Figure 2 and Figure 3, respectively. These materials are made from mono-substituted fatty acids and di-, tri- or tetra-functional hydroxyl compounds. They are not polyesters.

Polyesters are made with multifunctional acids and hydroxyl compounds. They offer the cosmetic formulator the potential to make products with a wide range of cushion and playtime. This, in turn, results in many cosmetically elegant formulations.

One of the major uses of complex esters is for low viscosity, cosmetically elegant oil phases. The PE esters have the most cushion and playtime while the NPG has the least cushion and is a dry oil.

The low viscosity is obtained using branched, monounsaturated or iso fatty acids. Table 1, Table 2, Table 3 and Table 4 compare oleate esters, eructate esters, C-20 guerbet acid esters and isostearate esters.

The guerbet C-20 esters have the lowest iodine value, meaning they have the best oxidative stability. Iodine value increases in the following order: guerbet C-20 esters, isostearate esters and euruic esters and oleate esters are about equal. Fragrance interactions also need to be considered when using esters with high iodine values.