Non-spherical hollow silica particles as SPF boosters

Abstract

Described herein are non-spherical hollow silica particles, a process for making non-spherical hollow silica particles, and the use of non-spherical hollow silica particles in sun care compositions. To form non-spherical hollow silica particles, deposition of a silica shell onto a calcium carbonate template using sol-gel chemistry is used. Subsequent dissolution of the calcium carbonate template forms voids (e.g., hollow interiors) in the non-spherical hollow silica particles.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 63 / 106,645, filed October 28, 2020, the disclosure of which is hereby incorporated by reference in its entirety.

Background Art

[0002] The sun protection factor (SPF) is used to evaluate the ability of a sun care composition to block, absorb, and / or scatter UV radiation (e.g., UVA radiation and / or UVB radiation). The sun care composition may contain physical UV blockers and / or chemical UV absorbers, which are described herein as sun protection actives. However, if the concentration of the sun protection active is too high, the aesthetic properties of the sun care composition are impaired, and / or undesirable toxicological effects and / or environmental problems will occur. Therefore, an SPF booster (e.g., a compound that is not recognized as a sun protection active but acts to increase the SPF) is highly desirable to be added to the sun care composition to increase the SPF of the sun care composition, for example, without adding more sun protection actives.

[0003] Therefore, what is needed are new SPF boosters and new processes for forming them.

Summary of the Invention

[0004] Non - spherical hollow silica particles, a process for making non - spherical hollow silica particles, and the use of non - spherical hollow silica particles in a sun care composition are described herein. To form the non - spherical hollow silica particles, deposition of a silica shell on a calcium carbonate template using sol - gel chemistry is used. Subsequent dissolution of the calcium carbonate template forms voids (e.g., a hollow interior) in the non - spherical hollow silica particles.

Brief Description of the Drawings

[0005] [Figure 1] This is a group of scanning transmission electron microscope (STEM) images of non-spherical hollow silica particles labeled as batches 1-5. [Figure 2] The images show the attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra of batch 1 non-spherical hollow silica particles at room temperature and after drying, along with the reference spectrum of tetraethyl orthosilicate (TEOS). [Figure 3] This figure shows the sun protection index (SPF) measurements for initial and heat-aged formulations, including a comparative sun care formulation (e.g., without SPF booster or with conventional SPF booster), a sun care formulation incorporating template material, and a sun care formulation containing non-spherical hollow silica particles (e.g., as an SPF booster). [Modes for carrying out the invention]

[0006] Non-spherical hollow silica particles, processes for producing non-spherical hollow silica particles, and the use of non-spherical hollow silica particles in sun care compositions are described herein. “Non-spherical” as used in relation to non-spherical hollow silica particles as described herein means that the particles are not generally spherical. Preferably, non-spherical hollow silica particles have an anisotropic shape (e.g., long axis and short axis). “Hollow” as used in relation to non-spherical hollow silica particles as described herein means that the particles have voids (e.g., hollow interior) defined by the shell of the silicon oxide particles. Multiple pores (e.g., channels) pass through the shell and extend from the hollow portion to the outer surface of the shell.

[0007] Non-spherical hollow silica particles can be prepared by depositing silica on an inorganic template (e.g., by a sol-gel process). The silica may be derived from silicate precursors, such as alkoxysilanes or alkyl silicates. Preferably, the process for producing non-spherical hollow silica particles includes obtaining calcium carbonate crystals to be used as a template, depositing silica shells on the template, and then dissolving the template with an acid to obtain non-spherical hollow silica particles. More preferably, tetraethyl orthosilicate is used to form the silica shells. The morphology of the non-spherical hollow silica particles may be a result of the morphology of the inorganic template; for example, the silica may be deposited relatively uniformly, for example, as a continuous silica shell. The inorganic template may be dissolved with an acid. The inorganic template may be calcium carbonate. The non-spherical hollow silica particles may contain less than about 2% by weight of organic material, preferably less than about 1.5% by weight of organic material, more preferably less than about 1.0% by weight of organic material.

[0008] This process may also be a surfactant-free process.

[0009] In another embodiment, the process conditions used to prepare the inorganic template are varied to obtain spherical calcium carbonate crystals for use as a template. In this case, the above process, for example, depositing silica on the inorganic template (e.g., via a sol-gel process), is followed to obtain spherical hollow silica particles.

[0010] A preferred process for producing non-spherical hollow silica particles includes dispersing a calcium carbonate template in ethanol, adding an ammonium solution, then slowly adding tetraethyl orthosilicate (TEOS), and adding an acid to dissolve the calcium carbonate template. This process may include quenching the reaction with ethanol before the acid addition step. This process may include about 30 to 90 minutes before quenching the reaction with ethanol. The non-spherical hollow silica particles may contain less than about 2% by weight of organic matter without further purification.

[0011] Calcium carbonate template material may be formed by slowly adding a calcium chloride solution to a sodium carbonate solution in the presence of ethylene glycol. After stirring for a certain period of time, the product (calcium carbonate) is separated by centrifugation. The centrifuged product is washed with ethanol. The concentration of the reagents, reaction time, and temperature may affect the template size.

[0012] The non-spherical hollow silica particles described herein preferably have an anisotropic shape (e.g., long axis and short axis). Transmission electron microscope (STEM) images may be used to determine particle size, which is measured manually using a scale bar. For example, STEM may be used to observe the lengths of the long and short axes, the presence of hollow voids, the dimensions of the voids, and the shell thickness, which are measured manually using a scale bar.

[0013] Non-spherical hollow silica particles have a long axis (e.g., maximum outer particle length) of about 450 nm to about 1650 nm. Preferably, the long axis may be greater than about 800 nm, greater than about 1000 nm, greater than about 1100 nm, and less than about 1227 nm, less than about 1300 nm, and less than about 1422 nm. More preferably, the long axis of the non-spherical hollow silica particles may be about 1100 nm to about 1200 nm, most preferably about 1143 nm.

[0014] Non-spherical hollow silica particles have a short axis (e.g., minimum outer particle width) of about 350 nm to about 1200 nm. It is understood that the short axis must be smaller than the long axis. Preferably, the short axis may be greater than about 570 nm, greater than about 700 nm, greater than about 750 nm, and less than about 810 nm, less than about 850 nm, and less than about 954 nm. More preferably, the short axis of the non-spherical hollow silica particles may be about 720 nm to about 820 nm, most preferably about 770 nm.

[0015] The major axis may be about 1.3 times, 1.4 times, 1.6 times, or 1.7 times larger than the minor axis. Preferably, the ratio of the major axis to the minor axis may be about 3:2 (for example, about 1.5:1).

[0016] Non-spherical hollow silica particles have a void long axis of about 400 nm to about 1350 nm (for example, the void length along the long axis of the non-spherical hollow silica particle). Preferably, the void long axis may be greater than about 800 nm, greater than about 850 nm, greater than about 900 nm, and less than about 950 nm, less than about 1000 nm, and less than about 1100 nm. More preferably, the void long axis of the non-spherical hollow silica particle may be about 842 nm to about 942 nm, most preferably about 892 nm.

[0017] Non-spherical hollow silica particles have a void short axis of about 200 nm to about 850 nm (e.g., the void length along the short axis of the non-spherical hollow silica particle). It is understood that the void short axis must be smaller than the void long axis. Preferably, the void short axis may be greater than about 400 nm, greater than about 550 nm, greater than about 570 nm, and less than about 652 nm, less than about 750 nm, and less than about 800 nm. More preferably, the void short axis of the non-spherical hollow silica particle may be about 540 nm to about 650 nm, most preferably about 595 nm.

[0018] The long axis of the void may be about 1.3 times, about 1.4 times, about 1.6 times, or about 1.7 times larger than the short axis of the void. Preferably, the ratio of the long axis to the short axis of the void may be about 3:2 (for example, about 1.5:1).

[0019] The non-spherical hollow silica particles have a shell thickness of about 50 nm to about 300 nm. Preferably, the shell thickness may be greater than about 73 nm, greater than about 84 nm, greater than about 88 nm, and less than about 92 nm, less than about 100 nm, and less than about 200 nm. More preferably, the shell thickness of the non-spherical hollow silica particles may be about 85 nm to about 95 nm, most preferably about 90 nm.

[0020] The non-spherical hollow silica particles described herein may be used in sun care compositions. Sun care compositions are personal care compositions for protecting the user from UV radiation. Examples of sun care compositions include compositions having an SPF rating (e.g., sunscreen compositions) and / or personal care compositions where UV blocking agents are beneficial, such as moisturizers and lip balms.

[0021] The sun care compositions described herein comprise non-spherical hollow silica particles and at least one sunscreen active substance (one or more (e.g., a mixture) sunscreen active substances). The sunscreen active substances are intended to include physical UV blockers (e.g., titanium dioxide, zinc oxide) and chemical UV absorbers (e.g., para-aminobenzoic acid, octyl methoxycinnamate). Examples of suitable sunscreen active ingredients include titanium dioxide, zinc oxide, para-aminobenzoic acid, octyl methoxycinnamate, ethylhexyl methoxycinnamate, ethylhexyl salicylate, octocrylene (2-ethylhexyl-2-cyano-3,3-diphenyl acrylate), butyl methoxydibenzoylmethane, avobenzone (4-t-butyl-4'-methoxydibenzoylmethane), oxybenzone, dioxybenzone, cinoxate (2-ethoxyethyl-p-methoxycinnamate), diethanolamine-p-methoxycinnamate, ethylhexyl-p-methoxycinnamate, isopentenyl-4-methoxycinnamate, 2-ethylhexyl This product contains silsalicylate, digalloyltrioleate ethyl 4-bis(hydroxypropyl)aminobenzoate, glycerylaminobenzoate, methyl anthranylate, homosalate (3,3,5-trimethylcyclohexyl salicylate), triethanolamine salicylate, 2-phenyl-benzimidazole-5-sulfonic acid, surisobenzone (2-hydroxy-4-methoxy-benzophenone-5-sulfonic acid), padimate A (amyl p-dimethylaminobenzoate), padimate O (octyldimethylp-aminobenzoate), 4-methylbenzylidene camphor, sunscreen active ingredients sold under the trade names ECAMSULE®, TINOSORB®, NEO HELIOPAN®, MEXORYL®, BENZOPHENONE®, UVINUL®, UVASORB®, and / or PARSOL®, and / or mixtures thereof. Preferably, the sunscreen active substance is a mixture of avobenzone, octisalate, octocrylene, zinc oxide, titanium dioxide, and homosalate.More preferably, the sunscreen active substance is a mixture of avobenzone, octocrylene, homosalate, zinc oxide, titanium dioxide, and octisalate.

[0022] Preferably, the sunscreen composition contains a total sunscreen active substance of the composition that is greater than about 5 parts by weight (pbw), greater than about 7 pbw, greater than about 10 pbw or equal thereto, and less than about 50 pbw, less than about 45 pbw, and less than about 40 pbw or equal thereto.

[0023] Preferably, the sunscreen composition contains non-spherical hollow silica particles of the composition that are greater than about 0.2 pbw, greater than about 0.5 pbw, greater than about 1 pbw or equal thereto, and less than about 5 pbw, less than about 4.5 pbw, and less than about 4.0 pbw or equal thereto. More preferably, the sunscreen composition contains about 3 pbw of non-spherical hollow silica particles based on the weight of the composition.

[0024] Preferably, the sunscreen composition may include at least one of a cosmetically acceptable skin softener, humectant, vitamin, moisturizer, conditioner, oil, silicone, suspending agent, carrier liquid, pigment, opacifier / pearlescent agent, surfactant, emulsifier, preservative, rheology modifier, colorant, pH adjuster, propellant, reducing agent, antioxidant, fragrance, foaming agent or defoaming agent, smoother, moisture-proof agent, and / or biocide. Preferably, the sunscreen composition may include at least one of a cosmetically acceptable skin softener, humectant, vitamin, moisturizer, conditioner, oil, silicone, suspending agent, surfactant, emulsifier, preservative, rheology modifier, pH adjuster, reducing agent, antioxidant, and / or foaming agent or defoaming agent. Preferably, the sunscreen composition may contain at least one of a humectant, surfactant, and / or skin softener.

[0025] The non-spherical hollow silica particles described herein can be used as an SPF booster in a sun care composition. If the concentration of the sunscreen active substance is too high, it will result in a decrease in the aesthetics of the composition (e.g., stickiness, greasiness, roughness, whiteness, etc.) and / or undesirable toxicological effects. As a result, an SPF booster (e.g., a compound that is not a recognized sunscreen active substance but acts to increase the SPF) is added to the sun care composition so that the SPF is increased without adding more sunscreen active substances. Preferably, the non-spherical hollow silica particles described herein act as an SPF booster for sun care compositions. Preferably, the SPF boost ratio (per 3 wt% booster) of the non-spherical hollow silica particles in the sun care composition is, for example, greater than about 2.5, greater than about 3, greater than about 3.5, more preferably greater than about 4.0, compared to a comparative composition without non-spherical hollow silica particles. The SPF boost ratio can be determined using Equation 1 (Example 7).

[0026] In use, a mammalian subject can be protected from damage caused by UV radiation (e.g., UVA radiation and / or UVB radiation) using a sun care composition comprising the hollow silica particles described herein. For example, a method of protecting a mammalian subject (e.g., mammalian skin) from damage caused by UV radiation includes applying a sun care composition comprising the hollow silica particles described herein to the skin of the mammalian subject.

[0027] The following examples are for illustrative purposes only and are not intended to limit the scope of the appended claims.

Examples

[0028] Example 1 Template Formation Calcium carbonate (CaCO3) templates were prepared as follows.

[0029] A CaCl2 solution was prepared by mixing 15.6 g of CaCl2 (anhydrous calcium chloride, manufactured by Fisher Scientific) with 120 mL of deionized water and 600 mL of ethylene glycol (99%, manufactured by Alfa Aesar) using magnetic stirring.

[0030] A NaHCO3 solution was prepared by mixing 24.4 g of NaHCO3 (sodium bicarbonate, >99.5%, manufactured by Sigma) with 240 mL of deionized water and 1.2 L of ethylene glycol using magnetic stirring. The NaHCO3 solution was placed in a 4 L glass beaker and continuously stirred using an overhead stirrer.

[0031] The CaCl2 solution was slowly poured into the NaHCO3 solution over several minutes. The system became turbid during the addition. Stirring was stopped after 30 minutes (time was measured from the start of CaCl2 addition). The solution was evenly divided into four 1L centrifuge bottles and centrifuged at 8000 rpm for 15 minutes. The supernatant was decanted. Approximately 300 g of ethanol (200 proof, Pharmoca-Aaper) was added to each centrifuge bottle, mixed well with the solid, and then centrifuged again at 8000 rpm for 15 minutes. The product was dispersed in 80 mL of ethanol, separated into four 45 mL centrifuge tubes, and a second washing was performed by centrifuging at 12000 rpm for 15 minutes. The wet slurry was transferred to a glass container and heated under vacuum at 80°C for 3 hours to obtain a dry powder containing a CaCO3 template characterized by an anisotropic shape with an average long axis in the range of 500–1350 nm and an average short axis in the range of 200–850 nm.

[0032] Example 2 Formation of non-spherical hollow silica particles Non-spherical hollow silica particles were prepared as follows.

[0033] The CaCO3 template was synthesized substantially according to the process of Example 1. After the initial wash, the CaCO3 template was dispersed in 76.5 mL of ethanol and placed in a 250 mL round-bottom flask to form a white suspension. While continuously stirring the white suspension at 260 rpm using a stirring plate, 6.6 mL of ammonium solution (ammonium hydroxide, 28-30% by weight, Pharmco-Aaper) and 7.8 mL of deionized water were added.

[0034] After mixing the system for 10 minutes, tetraethyl orthosilicate (TEOS) (Sigma) was supplied at a rate of 13 mL / h for 30 minutes using a syringe pump. The reaction was continued for another hour, after which it was quenched with 100 mL of ethanol. After stirring, a white solid slowly settled at the bottom of the flask. When clear separation of the solid and liquid was achieved, the clear solution at the top was decanted. The mixture was washed three times with 100 mL of ethanol, 100 mL of ethanol, and 100 mL of deionized water.

[0035] Subsequently, 80 mL of 1.5 M HCl solution (from 36.5-38 wt% hydrochloric acid, manufactured by Fisher Chemical) was slowly added to the solid while stirring at 260 rpm. Vigorous foaming was observed during the addition, and then the white suspension became semi-transparent. The system was stirred for 30 minutes, and then centrifuged at 10,000 rpm for 10 minutes. The product was washed twice with 100 mL of water and once with 100 mL of ethanol. The wet slurry was transferred to a glass container and heated under vacuum at 110°C for 3 hours to obtain a dry powder.

[0036] Example 3 Formation of non-spherical hollow silica particles Non-spherical hollow silica particles were prepared substantially according to the process of Example 2 to obtain batches 1 to 5. All five batches were prepared using the template process of Example 1, and the size differences in Table 1 (below) may be due to the particle size distribution.

[0037] Figure 1 shows a group of scanning transmission electron microscope (STEM) images of non-spherical hollow silica particles labeled Batch 1–5, illustrating the spherical hollow morphology. Batch 1 and Batch 2 are shown at the first magnification. Next, Batch 2 is shown again at a relatively low magnification. Batch 3–5 are shown at intermediate magnifications. STEM imaging was performed using an FEI Titan probe-corrected field emission gun (FEG) transmission electron microscope (TEM) operating at an accelerating voltage of 200 keV. Images were acquired at a magnification range of 13 kx–34 kx with an image size of 2048 × 2048.

[0038] Particle size measurements were performed manually using ImageJ software, and the results are summarized in Table 1. The non-spherical hollow silica spheres in Figure 1 have an anisotropic shape with an average major axis in the range of approximately 800 nm to 1500 nm and an average minor axis in the range of approximately 500 nm to 1000 nm. The non-spherical hollow silica spheres in Figure 1 have a relatively thin shell with a thickness that varies between approximately 70 nm and 120 nm.

[0039] The dimensions of the non-spherical hollow silica particles are shown in Table 1. [Table 1]

[0040] Morphologically, non-spherical hollow silica particles are anisotropic and hollow. Non-spherical hollow silica particles are relatively large in terms of, for example, the average particle long axis, average particle short axis, average void long axis, and average void short axis (1143 nm, 770 nm, 892 nm, and 595 nm, respectively).

[0041] Example 4 Batch 1 of non-spherical hollow silica particles from Example 3 was characterized. Figure 2 shows the attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra obtained using a Thermo Nicolet iS-50 FTIR spectrometer with a single-bounce diamond ATR. The non-spherical hollow silica particles of batch 1 were analyzed at room temperature (RT) (purple line), the same samples were analyzed after drying at 200°C (red line), and the reference spectrum for tetraethyl orthosilicate (TEOS) was analyzed (green line).

[0042] Referring to arrow 1, between wavenumbers 4000 and 3000, the OH stretching mode appears in room temperature batch 1 due to the presence of water. Part of the peak may also be attributable to the presence of SiOH.

[0043] Referring to Zone A, the CH mode located around 3000 cm⁻¹, as shown in the TEOS spectrum, was not found in the non-spherical hollow silica sample, thus indicating the absence of detectable amounts of CH. Therefore, since the detection limit of ATR-FTIR is typically 1 wt%, the organic matter content in the non-spherical hollow silica sample can be stated as less than 1 wt%, and ultimately less than 2 wt%. Compared to the RT-treated sample, the 200°C-treated sample showed a significant decrease in the intensity of broad peaks above 3000 cm⁻¹, due to water removal.

[0044] Referring to Zone B, the lines show artifacts from the ATR crystal.

[0045] Referring to arrow 2, the small peak on the RT sample represents the water-OH bending mode.

[0046] Peaks observed below 2000 cm⁻¹ are characteristic of various SI-O stretching modes. Arrow 3 points to the strongest of these peaks.

[0047] Below 1000 cm⁻¹, the RT and 200°C treated samples exhibited two Si-O stretching modes due to hydroxyl group condensation. The TEOS sample showed relatively large Si-OH stretching (condensation upon heating). In other words, TEOS showed the maximum peak intensity associated with the Si-OH stretching mode. The RT sample showed some mode, but the peak was the least significant in the 200°C dried sample because most of the Si-OH was condensed.

[0048] It should be noted that the sampling depth for ATR-FTIR is generally on the order of a few microns. Since the particle size of non-spherical hollow silica samples is smaller, for example, 1143 nm × 770 nm on average (see Table 1), ATR-FTIR measurement can be considered a bulk measurement.

[0049] Example 5 (Comparison) To confirm the SPF of the comparative sun care compositions, comparative batches A and B of sunscreen formulations containing the ingredients listed in Tables 1 and 2 were prepared. [Table 2]

[0050] The quantities are listed in parts by weight (pbw). Water is added until the total equals 100 pbw (for example, in comparative batch B, there is less than 3.0 pbw of water).

[0051] The components of Phase A (excluding SYMSAVE® H-hydroxyacetophenone antioxidant / smoothing agent) were mixed together and heated to 70°C while stirring. At 70°C, SYMSAVE® H-hydroxyacetophenone antioxidant / smoothing agent was added to the Phase A container and mixed until the contents were completely dissolved.

[0052] In a separate container, the components of phase B were mixed together and heated to 75°C until all components were melted or dissolved. With stirring (e.g., 500 rpm if no splash was used), phase B was gradually mixed into phase A at 70°C for 5 minutes. Half of phase C was added to the A / B mixture while homogenizing. The mixture was then homogenized at high speed for 3 minutes, after which it was switched to an overhead stirrer at 400 rpm. Subsequently, the remaining half of phase C was mixed into the formulation.

[0053] Heating and stirring of the A / B / C mixture were stopped, and it was cooled to 45°C. Phase D was added, and high-shear mixing was continued until the mixture reached room temperature.

[0054] Comparative batch A does not contain an SPF booster. Comparative batch B contains SUNSPHERES® hollow polystyrene spheres, which are SPF boosters.

[0055] Example 6 To confirm the SPF of the comparative sun care compositions, comparative batches C and D of sunscreen formulations containing the ingredients listed in Tables 1 and 3 were prepared. [Table 3]

[0056] The quantity is listed in parts by weight (pbw). Add water until the total is 100pbw.

[0057] The components of Phase A (excluding SYMSAVE® H-hydroxyacetophenone antioxidant / smoothing agent) were mixed together and heated to 70°C while stirring. At 70°C, SYMSAVE® H-hydroxyacetophenone antioxidant / smoothing agent was added to the Phase A container and mixed until the contents were completely dissolved.

[0058] In a separate container, the components of phase B were mixed together and heated to 75°C until all components were melted or dissolved. With stirring (e.g., 500 rpm if no splash was used), phase B was gradually mixed into phase A at 70°C for 5 minutes. Half of phase C was added to the A / B mixture while homogenizing. The mixture was then homogenized at high speed for 3 minutes, after which it was switched to an overhead stirrer at 400 rpm. Subsequently, the remaining half of phase C was mixed into the formulation.

[0059] Heating and stirring of the A / B / C mixture were stopped, and it was cooled to 45°C. Phase D was added, and high-shear mixing was continued until the mixture reached room temperature.

[0060] Batch C contains CaCO3 template material. Batch D contains a mixture of non-spherical hollow silica particle batches 1-5 (Table 1) to provide a sufficient amount of material for testing.

[0061] Example 7 32.5 mg of each suncare composition from Examples 5 and 6 was coated onto 5 cm x 5 cm PMMA plates using a wire rod. The drawdown films were dried for at least 30 minutes before SPF measurement to allow sufficient moisture to evaporate.

[0062] In vitro SPF was measured using a UV-2000S analyzer equipped with an integrating sphere and SPF operating software supplied by LabSpheres, Inc. (North Sutton, New Hampshire, USA). The UV-2000S measured the UV absorbance spectrum of the drawdown sunscreen film over UV radiation wavelengths (290-400 nm) and calculated the SPF value based on the UV absorbance spectrum. Nine data points were collected (for example, from different locations on the film specified by UV-2000S), and this was repeated three times for each formulation.

[0063] The sunscreen formulations were subjected to heat aging at 45°C for 2 weeks, 1 month, and 2 months, and their SPF was tested.

[0064] Figure 3 shows the SPF measurements of the initial and heat-aged formulations, including comparative suncare formulations (e.g., comparative batch A (without SPF booster) and comparative batch B (with conventional SPF booster), a suncare formulation incorporating template material (batch C), and a suncare formulation containing non-spherical hollow silica particles (e.g., as an SPF booster) (batch D). Figure 3 shows the SPF for comparative batch A, comparative batch B, batch C, and batch D at each time point. The results are also shown in Table 4. [Table 4]

[0065] CaCO3 particles provided a good SPF boost. Surprisingly, non-spherical hollow silica particles (batch D) yielded a very high SPF boost efficiency, four times higher than the commercially available benchmark (comparative batch B) before thermal aging. After two months of thermal aging, the SPF boost ratio of batch D remained three times higher than the commercially available benchmark (comparative batch B).

[0066] To compare the compositions, the SPF boost ratio was calculated using Equation 1.

number

[0067] It is understood that this disclosure is not limited to the embodiments specifically disclosed and illustrated herein. Various modifications of the invention will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the scope of the appended claims. Furthermore, each detailed scope includes all combinations and partial combinations of scopes, as well as the specific figures contained therein.

Claims

1. 1. A sun care composition comprising: non-spherical hollow silica particles having a major axis and a minor axis, the average minor axis being greater than 400 nm; at least one sunscreen active; 1. A sun care composition comprising:

2. 10. The suncare composition of claim 1, wherein said non-spherical hollow silica particles have a shell thickness of greater than about 50 nm.

3. 3. The sun care composition of claim 1, wherein said non-spherical hollow silica particles have a major axis that is at least 1.25 times greater than said minor axis.

4. A suncare composition according to any one of claims 1 to 3, wherein the non-spherical hollow silica particles have an average major axis of greater than 500 nm.

5. A suncare composition according to any preceding claim, wherein the non-spherical hollow silica particles have an average pore length greater than 350 nm.

6. A suncare composition according to any preceding claim, wherein the non-spherical hollow silica particles have an average void minor axis of less than 1100 nm.

7. A suncare composition according to any one of claims 1 to 6, wherein the suncare composition has a Sun Protection Factor (SPF) boost of greater than about 3.

8. A sun care composition according to any preceding claim, further comprising hollow polystyrene spheres.

9. 9. The sun care composition of any one of claims 1 to 8, further comprising at least one of a cosmetically acceptable emollient, carrier liquid, pigment, humectant, vitamin, moisturizer, conditioner, oil, silicone, suspending agent, surfactant, emulsifier, preservative, rheology modifier, pH adjuster, reducing agent, antioxidant, and / or foaming agent or defoamer.

10. 1. A process for making non-spherical hollow silica particles having a major axis and a minor axis, wherein the average minor axis is greater than 400 nm, said non-spherical hollow silica particles containing less than about 2% by weight of organic material without further purification, said process comprising: Dispersing a calcium carbonate template in ethanol; adding an ammonium solution; then slowly adding tetraethyl orthosilicate (TEOS); adding an acid to dissolve the calcium carbonate template; The process includes:

11. 11. The process of claim 10, further comprising quenching the reaction with ethanol prior to the acid addition step.

12. 12. The process of claim 11, further comprising waiting from about 30 minutes to about 90 minutes before quenching the reaction with ethanol.

13. 11. The process of claim 10, further comprising forming a calcium carbonate template by slowly adding a calcium chloride solution to a sodium carbonate solution in the presence of ethylene glycol.

14. Use of non-spherical hollow silica particles having a major axis and a minor axis, with an average minor axis greater than 400 nm, as an SPF booster in a sun care composition.

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