| 摘要: | 由於臭氧層遭受破壞以及紫外線穿越大氣層進入地表含量逐漸增加，許多不利肌膚問題隨之而來。因此，除了在白天避免肌膚直接過度暴曬於太陽光下，還須加強肌膚防護措施，最重要的就是使用適當之防曬產品。雖然市售防曬產品琳瑯滿目，但為了因應防曬市場需求及消費者使用之安全，以及考慮防曬產品在運輸過程，可能會因環境的變異，導致產品因溫度過高或陽光照射產生防曬產品變質或不安定，所以，本研究擬開發品質及安定性較佳之防曬產品。
本研究主要目的是探討含單一防曬成份，混合防曬成份之添加和光安定劑的有無對防曬霜之 SPF 有效性與儲存安定性。首先選擇 Olivem 1000、Arlacel 165、Tween 60 / Span 80 作為乳化系統，並利用 Isopropyl Palmitate (IPP)、Finsolv TN 及 Cyclopentasiloxane 三種基礎油脂調製基礎乳液。而防曬成分則選擇最被常用的 Octyl Methoxy Cinnamate (PMCX)、4-Tert-Butyl Methoxy Dibenzoyl Methane (P1789)、 Octocrylene 及 Titanium Dioxide (TiO2) 四種。實驗開始先添加單一防曬成分 PMCX 至基礎乳液配方，所得防曬霜再經 45℃ 加速老化後測定其流變性質、黏度變化、粒徑分佈及大小，和相分離等物性評估以篩選出較佳之乳化系統。實驗結果，Tween 60 / Span 80 被選為最佳乳化系統，接著再利用此一最佳乳化系統進行其他防曬成份之單一添加及混合添加，乳化後所得之防曬產品進行物性評估並以 in vitro SPF 測定儀 (Ultraviolet Transmittance Analyzer) 測定其 SPF 值。此外，也進行光老化實驗，觀察其 SPF 之經時變化。
在物性評估方面，經研究結果顯示，Tween 60 / Span 80之界面系統之防曬產品 (不論含單一防曬成份或混合防曬成份) 的外觀與安定性較其他兩種界面系統佳。而且Tween 60 / Span 80 系統之防曬產品均具有切變減稀之流體性質。而在粒徑大小及分佈方面，同時添加高濃度之 PMCX 及低濃度之 P1789 ，其乳化粒徑大小皆在 10 μm以內，而粒徑分佈 (span) 為1.3 ~ 6.7。但若提高 P1789 之添加濃度，其粒徑分佈則會漂移到較大之範圍 (span 約在5.9 ~ 9.3之間)。而他們的安定性都可達60 天以上。
經 SPF 有效性顯示，SPF 防護效能隨著防曬劑成分濃度之增加而提高，其中以單一防曬成份 P1789 添加者，有較好的正比線性關係，其線性相關係數（r）為 0.999，單一 PMCX 之 r 為 0.932。此外，我們發現 PMCX 防曬成份會有光分解的問題，也就是說只要配方含有 PMCX，在照光後 SPF 會降低。所幸，在照光實驗中發現混合防曬成份之添加中，當 P1789 添加量相對高於其他防曬成份時，有抑制 SPF 降低之趨勢；另外，在防曬產品中添加光安定劑也有抑制光分解之作用。顯然在配方中選擇適當比例含量的防曬成份以及應用光安定劑都能使防曬霜有較穩定的 SPF 值。所以慎選配方組成是獲得優質產品的不二法門。
綜合以上研究所得之最佳防曬配方除了有好的光安定性外，其 SPF 值為 32.32，而且儲存安定性可達 60 天以上。配方組成如下: Tween 60為2.5%、Span 80為2.5%、Isopropyl palmitate為3.0%、Finsolv TN為3.5%、CM040為3.5%、PMCX為3.5%、P1789為3.0%、Octocrylene為3.5%、Oxynex ST為0.5%、Germaben II為0.8%、Thickener為1.50%、Propylene Glycol為5.0%、D.W.為67.2%。
The increasing amount of UV sunlight that reaches the earth’s surface makes human skin being in the risk of several harmful changes because of ozone layer depletion. It is well known that overexposure to UV radiation will cause wrinkling, premature aging of the skin, hyperpigmentation macules and even skin cancer. People can protect their skin by avoiding overexposure to sunlight during the daytime. In addition, the use of Sunscreen products with broadspectrum UV-absorption should be recommended in order to counteract against all kind of UV-induced skin damage. Many UV filters are approved and promising candidates for sun-protection formulations. A great number of sunscreen products with or without other active components are available in the commercial market. However, some of them can cause photodegradation under extreme conditions such as UV radiation and evolved temperature. The occurrence of photodegradation will result in the disadvantage changes in physical properties and the lower efficacy. Hence, in order to guarantee storage stability, constant efficacy of the product, and the safety of consumer’s application, the UV filters used should not be altered by UV sunlight. These have led to the intensive development of elegant sunscreen products.
The aim of this study was to evaluate the influence of single filter and different filter combinations and a photostabilizer on the storage stability and the sunburn protection of sunscreen products. In order to formulate sunscreen products, three surfactants, Olivem 1000、Arlacel 165、and Tween 60 / Span 80 as emulsifiers and four oily ingredients, Isopropyl Palmitate, C12-15 Alkyl Benzoate (FinsolvTN), and Cyclopentasiloxane as oil phase, were examined. These surfactants and oil components have been used in the cosmetic industry. And then three chemical UV filters, PMCX (Octyl Methoxy Cinnamate), P1789 (4-Tert-Butyl Methoxy Dibenzoyl Methane) and Octocryene, and one physical UV filter, TiO2 (Titanium oxide) were selected because they were the most widely used UV filters which were approved. In the beginning we formulated three kinds of emulsions as a control. And then we performed studies using the incorporation of single PMCX into the three kinds of w/o emulsions containing various kinds of emulsifiers and investigated their physicochemical properties including viscosity, rheological behavior, particle size and distribution, and physical changes during typical accelerated test. The results indicated that using Tween 60 / Span 80 as emulsifiers provide better storage stability than other two emulsifiers. The following studies were performed in order to investigate the effect of the incorporation of different UV filters combinations at varying levels into emulsion containing Tween 60 / Span 80 on the stability and the efficacy of the obtained sunscreen products. Finally, considering the ease of photodegradation, we incorporated a photostabilizer into the sunscreen products and their photostability were tested by Labsphere UV-1000s transmittance analyzer (according to Food and Drug administration method). The difference in photostability was compared before and after typical accelerated test.
In relating to physicochemical properties, the results showed that using Tween 60 / Span 80 as emulsifiers, all the obtained sunscreens with single UV filters or different UV filter combinations have an esthetic appearance. We have demonstrated that all the obtained sunscreen products had pseudoplastic behavior which produces a coherent protective film covering the skin surface with evenly distributed UV filters. Regarding to particle size and distribution, when incorporating a combination of PMCX of high level with a lower level of P1789 into sunscreen products, their particle size are below 10 μm and there is a range of lower polydisperse index (from 1.3 to 6.7). In contrast, the increasing amount of P1789 can result in a higher range of polydisperse index (from 5.9 to 9.3). In addition, their storage stability is also up to 60 days after accelerated test.
On the other hand, the efficacy of all the sunscreen products was measured. These results indicate that the efficacy was well correlating with the amounts of the used UV filters. Incorporating single UV filter provide a better correlation coefficient (r=0.999 for single P1789; r=0.932 for single PMCX) than mixture of different UV filters. Besides, we found that the sunscreen foundations containing PMCX has problem with a photodegration and produce a reduced SPF value during the exposure to UV irradiation from solar simulator. In other words, the efficacy of the sunscreen formulations earily decreased in the presence of PMCX due to its photodegration. Fortunately, it was found that a photstabilizer or a combination of P1789 of higher level with lower other UV filters can contribute to a constant efficacy and good physicochemical properties of the sunscreen formulations. Therefore, it is important for optimizing sunscreen formulations to choice the right compositions.
Based on these findings, a desired sunscreen product was obtained. With high SPF of 32.32, good stability at 45℃testing for 60 days, good photostability, esthetic appearance, and good skin feel, it is composed of Tween 60 2.5%、Span 80 2.5%、Isopropyl palmitate 3.0%、Finsolv TN 3.5%、CM040 3.5%、PMCX 3.5%、P1789 3.0%、Octocrylene 3.5%、Oxynex ST 0.5%、Germaben II 0.8%、Thickener 1.50%、Propylene Glycol 5.0%、D.W. 67.2%。 |
