68 SUN CARE
TABLE 2: MINERAL SUNSCREEN BASE Phase Ingredients A Water
INCI Water
GreenDiol Edeta BD
Pellicer L-30 Keltrol CG
B
Emulgade PL 68/50
SiClone SR-5 Jeechem CTG MZX-304OTS
MT-100TV C
Euxyl PE9010 SPF Booster
2,3-Butanediol Disodium EDTA
Water (and) Sodium Dilauramidoglutamide
Xanthan Gum
Cetearyl Glucoside (and) Cetearyl Alcohol
Cetearyl Alcohol Cetearyl Alcohol Jeechem DIA
Diisopropyl Adipate
Isohexadecane (and) Isododecane (and) C13-15 Alkane
Caprylic/Capric Triglyceride
Zinc Oxide (and) Triethoxycaprylylsilane
Titanium Dioxide (and) Aluminium Hydroxide (and) Stearic Acid
Phenoxyethanol (and) Ethylhexylglycerin
Various Suppliers: 1. Presperse 2. BASF 3. CP Kelco 4. HallStar 5. Jeen International 6. Schulke
All in vitro results were reported according to the FDA’s proposed order 000008,2
which
limits the label SPF value of a sunscreen to 60+. The proposed order also calls for labelling with the lowest number of the tested range (in in vivo testing), and that range is used to report results.
Opacity measurements Sunscreen opacity was tested by creating drawdowns with a 4 mil drawdown bar on black and white Leneta paper. The paper was left to dry at least overnight, and opacity was measured using an X-Rite VS450 spectrophotometer. The percentage of opacity (0% being completely transparent and 100% being completely opaque) was calculated using the following formula:
Opacity: Yblack backing /Ywhite backing *100
Mineral sunscreen base As the market is trending towards mineral based sunscreen products, this was chosen as
Post-Add
Supplier % w/w 51.25
1
2 1
3 2 4
5 1
5 1
1
6 1
2.50 0.05
0.20 0.30 3.50 1.50
10.00 5.00
10.00 8.00
7.00
0.70 1 or 3
C B
TABLE 3: ZINC OXIDE SUNSCREEN BASE Phase Ingredients
INCI A Water GreenDiol Water 2,3-Butanediol
Sodium Phytate Sodium Phytate Euxyl PE9010
Pellicer L-30 Keltrol CG
Emulgade PL 68/50
Xanthan Gum
Cetearyl Glucoside (and) Cetearyl Alcohol
Cetearyl Alcohol Cetearyl Alcohol Jeechem DIA
Boosting Powder SiClone SR-5 Jeechem CTG MZX-304OTS
the initial system for evaluation. The mineral sunscreen base used is shown
in Table 2. The targeted SPF is 30. The final formula contained 7% titanium dioxide and 8% zinc oxide and passed 12-week stability testing at all conditions (5°C, room temperature, 45°C, 50°C and three cycles of freeze thaw). In vitro SPF on the mineral base containing
no boosters was measured to be SPF 29.0 (reported as 25, in accordance with FDA Proposed Order 000008)2
. Selected boosters
were then added to the formula at 1% or 3%, either post emulsification or added to the oil phase prior to emulsification.
Zinc oxide sunscreen base Along with the trend toward mineral sunscreens, there has also been consumer interest in mineral sunscreen systems that contain only zinc oxide. One performance advantage of zinc oxide over titanium dioxide is that it is less opacifying/whitening. However, it is also less efficient as a UV filter, and so higher loading levels could be
TABLE 4: IN VITRO SPF RESULTS, MINERAL UV FILTER SYSTEM Booster INCI
1%
No booster Silica (1)
Calcium Sodium Borosilicate Silica (2) Silica (3) Wat
Silica (and) Methicone Silica (4) Silica (5)
Microcrystalline Cellulose (1)
Microcrystalline Cellulose (and) Cellulose Gum
Oryza Sativa (Rice) Starch (and) Oryza Sativa (Rice) Bran Wax
Silica (6) PERSONAL CARE March 2025
50 40 40 40 40
60+ 60+ 40
60+ 60+
60+ 60+
3% 25
40 50 40 50 50
60+ 60+ 60+ 100
50
60+ 60+
60+ 60+ 60+ 60+ 60+ 60+ 60+ 60+ 60+
60+ 60+
60+
60+ 50
60+ 60+ 60+ 60+ 60+ 60+ 60+
60+ 40
60+ 1% In-Process 3%
Diisopropyl Adipate Various
Isohexadecane (and) Isododecane (and) C13-15 Alkane
Caprylic/Capric Triglyceride
Zinc Oxide (and) Triethoxycaprylylsilane
Suppliers: 1. Presperse 2. Making Cosmetics 3. Ashland 4. CP Kelco 5. BASF 6. HallStar 7. Jeen International
needed to achieve the desired SPF value. A smaller number of powders were evaluated in this system, and only in-process addition was used. The zinc oxide sunscreen base is shown in Table 3.
Results and discussion Mineral sunscreen system In vitro results (Table 4) confirm that many powders can act as SPF boosters in this system, offering flexibility to the formulator. All materials had some boosting effect at both use levels evaluated, and with either processing method. We see that the results can vary by
processing method (in-process vs post-add), and that sometimes adding more boosting powder can lead to less SPF boosting. In some cases, ‘less is more’ – when the boosting powder level is increased, it might be too high to obtain good dispersion of the powder. If the powder is not well distributed in the sunscreen, it will not be as effective in diffusing the UV back to the sunscreen filter.
TABLE 5: OPACITY RESULTS, POST-ADD PROCESSING, MINERAL UV FILTER SYSTEM
Booster INCI No booster Silica (1)
Calcium Sodium Borosilicate Silica (2) Silica (3) Wat
Silica (and) Methicone Silica (4) Silica (5)
Microcrystalline Cellulose (1)
Microcrystalline Cellulose (and) Cellulose Gum
Oryza Sativa (Rice) Starch (and) Oryza Sativa (Rice) Bran Wax
Silica (6) 1% 32.7
33.6 48.8 36.7 41.6 43.5 43.7 47.7 41.3 42.9
42.6
43.2 47.4
41.4 54.4 53.9 53.6 55.2 56.1
56.9 38.5 38.1
44.1 55.1 50.5
www.personalcaremagazine.com 3%
Phenoxyethanol (and) Ethylhexylglycerin
Water (and) Sodium Dilauramidoglutamide
Supplier % w/w 44.95
1
2 3
1
4 5 6
7 1
1
7 1
2.50 0.05
1.00
0.20 0.30 3.50 1.50
10.00 1 or 3
5.00
10.00 20.00
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