Sunscreen: an important step in skin care

Octyl 4-methoxycinnamate applied in cosmetics

Ethylhexyl methoxycinnamate is also called 4-methoxycinnamate-2-ethylhexyl ester, octyl p-methoxycinnamate, 2-ethylhexyl p-methoxyl Cinnamate, OMC, Octinoxate, Octyl methoxycinnamate. Ethylhexyl methoxycinnamate is mainly used as a chemical sunscreen in cosmetics and skin care products, with a risk factor of 6, which is relatively safe and can be used with confidence. Cosmetic skin care products containing ethylhexyl methoxycinnamate are suitable for pregnant women use with caution, ethylhexyl methoxycinnamate is not acne-causing.

The oil-soluble UVB sunscreens that are very common on the market at present have an absorption wavelength between 290-320nm, are widely used all over the world, and have relatively low skin irritation. The safety of this ingredient is somewhat controversial. It is a penetration enhancer and is easily absorbed into the skin. There is a saying that it will have estrogen-like effects and should not be used in pregnant women and children. Another argument is that all experiments were conducted on rats and mice, and the experiments were carried out under special conditions of high concentrations, and the results were immature. At present, the regulatory agencies in various countries have not confirmed the risk of this ingredient, and the maximum addition amount limited by domestic and EU regulations is 10%.

Skin aging is the result of a combination of "intrinsic" and "extrinsic" factors.

Internal, in the final analysis, is actually the aging of "organs". In fact, human skin is like a "mirror", reflecting the state of your internal organs. For example, if your liver is not good, it is easy to turn yellow and dark, and it is easy to develop spots; Chinese medicine believes that "kidney" is the main water, so if your kidney is not good, often the fire will rise, the skin will be dry and appear Wrinkles, and the kidneys are responsible for filtering the "blood" of the whole body. If the kidneys are not good, the toxins in the blood cannot be discharged in time, and these accumulated toxins in the body will also accelerate the aging of the skin.

So, our point is that if a person looks young on the outside, then her internal organs must be no different.

How to prevent sunscreen correctly?

When it comes to fighting the damage of external factors to the skin, the most important job is "sun protection"!

How can you effectively protect your skin from UV rays in the hot summer? Is your sunscreen correct?

Use sunscreen after the "face cream" as the last step of basic maintenance and before any makeup base. It is recommended that after applying the face cream, you can do a small massage on the face first, so that the ingredients in the cream are fully absorbed by the skin, and then apply the sunscreen, so that the cream does not float on the face, and the sunscreen will be mixed together and affect the effect. Generally speaking, sunscreen must be tightly attached to the skin in order to exert the maximum effect.

Especially some chemical sunscreens need to be absorbed by the skin and then metabolized. Therefore, if the sunscreen is applied after the base makeup, the effect of the sunscreen will be greatly reduced due to the "isolation" effect of the base makeup.

SPF

According to the different wavelengths, ultraviolet rays are divided into three types:

UVA: UVA with the longest wavelength, is not absorbed by the ozone layer at the top of the atmosphere, can penetrate the dermis, penetrates deeper into the skin than UVB, tans the skin, and causes damage to lipids and collagen, causing skin irritation. Photoaging and even skin cancer, so UVA will not only stimulate the synthesis of pigment and make the skin "dark", but also the main cause of skin "aging" and fine lines.

UVB: Medium-wave ultraviolet rays, which can reach the dermis layer, causing sunburn, erythema, tanning, etc., but most of UVB is absorbed by the ozone layer, and can be blocked by glass, parasols, clothes, etc.

UVC: UVC is almost completely absorbed by the atmosphere, and there are only very few cases where we encounter it.

Sun protection reasons

When the skin is exposed to excessive ultraviolet rays, it will damage epidermal cells; activate tyrosinase, accelerate pigment synthesis, destroy the skin's moisturizing function, make the skin dry, damage the elastic fibers in the dermis, and cause fine lines to appear. Under intense exposure, it can also cause skin irritation and burns. In abnormal cases, it can become pigmented skin cancer, etc.

After the skin is irradiated with ultraviolet rays for a long time at one time, chronic erythema (sunburn) appears on the skin after several hours to more than 10 hours, the color is bright red, the skin is edema, and blisters may occur in severe cases. The skin erythema reaction peaked on the second day after sun exposure, and after about a week, the erythema subsided, with scaling and pigmentation, and the skin felt burning and painful. In severe cases, it may be accompanied by systemic reactions, such as fever, headache, fatigue, nausea and general discomfort. Palpitations, delirium and shock even occur.

The main types of ultraviolet rays that sunscreen blocks or absorbs are UVA (long-wave ultraviolet), UVB (medium-wave ultraviolet) and UVC (short-wave ultraviolet), and different ultraviolet rays can damage the skin differently.

Sunscreen products

Definition

Sunscreen products refer to cosmetics that add sunscreen agents that can block or absorb ultraviolet rays to prevent skin from being tanned and sunburned.

     Classification

Sunscreen products can generally be divided into physical sunscreens, chemical sunscreens and biological sunscreens. It can also be divided into sunscreen, sunscreen lotion, sunscreen oil, sunscreen stick, sunscreen gel, sunscreen spray, etc. according to the formulation of sunscreen products.

Judgment method

When choosing sunscreen products, you can choose sunscreen products by judging the UV protection ability of sunscreen products.

The algorithm used by brands in Japan and the United States is the sun protection factor (SPF), while in European countries, mainly France, it is expressed by "IP".

In addition, there is PFA or PA. PFA or PA is an objective evaluation of the protective effect of sunscreen cosmetics on UVA; this label is based on skin tanning or pigmentation, and mainly reflects the protective effect on UVA; PA grades start with + No. to represent

Main ingredients of sunscreen products

     Zinc oxide

Zinc oxide is an important and widely used physical sunscreen agent that shields ultraviolet rays by absorption and scattering. Zinc oxide is an N-type semiconductor, and the electrons in the valence band can accept the energy in the ultraviolet light to make a transition, which is also the principle of their absorption of ultraviolet light. The function of scattering ultraviolet rays is related to the particle size of the material. When the size is much smaller than the wavelength of ultraviolet rays, the particles can scatter the ultraviolet rays acting on them in all directions, thereby reducing the intensity of ultraviolet rays in the irradiation direction. In addition, if the particle size of this material is too large, unnatural whitening will appear on the skin. Nanoscale particles therefore have significant advantages over normal sizes.

Titanium dioxide

Titanium dioxide's strong UV resistance is due to its high refractive index and high photoactivity. Its anti-ultraviolet ability and its mechanism are related to its particle size: when the particle size is large, the blocking of ultraviolet rays is mainly reflection and scattering, and it is effective for both medium-wave and long-wave ultraviolet rays. The sunscreen mechanism is simple covering, which is a general physical sunscreen, and the sunscreen ability is weak; as the particle size decreases, the light can pass through the particle surface of titanium dioxide, and the reflection and scattering of ultraviolet rays in the long-wavelength region are not obvious, while the middle The absorption of ultraviolet rays in the wave region is significantly enhanced. 

Its sunscreen mechanism is to absorb ultraviolet rays, mainly absorbing ultraviolet rays in the middle wave region. It can be seen that titanium dioxide has different sunscreen mechanisms for ultraviolet rays of different wavelengths. The blocking of ultraviolet rays in the long wave region is mainly scattering, and the blocking of ultraviolet rays in the medium wave region is mainly absorption.

Octyl Salicylate

Octyl salicylate Octyl salicylate has a conjugated π bond, which can absorb ultraviolet rays and convert the energy of ultraviolet rays into heat to release it to achieve the purpose of sun protection. Octyl salicylate can absorb ultraviolet rays in the 280-300nm band, As a UVB absorber, it is used in sunscreen makeup. Although octyl salicylate has a small UV absorption capacity, it is safer, less toxic, and cheaper than most other sunscreens, so it is a type of UV absorber that people use more often.

Octyl Methoxycinnamate

There is a large conjugated π bond in the molecule of octyl methoxycinnamate. This conjugated structure can be regarded as a benzene ring as the core, one side extends to include the oxygen atom in the substituent methoxy group, and the other side extends to the double bond and ester group in the other substituent group. This conjugated structure determines that the substance has the property of absorbing ultraviolet rays. Experiments revealed that octyl methoxycinnamate can absorb ultraviolet rays in the wavelength range of 280-310 nm, with the maximum absorption at 311 nm.

2-Hydroxy-4-methoxybenzophenone

In the benzophenone structure, the hydroxyl hydrogen on the benzene ring and the adjacent carbonyl oxygen can form an intramolecular hydrogen bond, and the sunscreen mechanism constitutes a chelate ring. After absorbing ultraviolet light, the molecule undergoes thermal vibration, the hydrogen bond is destroyed, and the chelate ring is opened. At this time, the compound is in an unstable high-energy state. In the process of returning to the original low-energy stable state, excess energy is released. In this way, high-energy, harmful ultraviolet light becomes low-energy, harmless heat energy.

At the same time, the carbonyl group is excited, tautomerism occurs, and the formation of the enol structure can also consume a part of the energy.

Is higher SPF better?

Some people blindly choose to apply a "high" SPF to their face in order to pursue the "effect" of sun protection, and only need SPF50+ all year round to feel at ease. In fact, I personally do not recommend that you apply products above SPF30+ on your face. Why We all know that sunscreen is divided into chemical and physical. If it is a physical sunscreen, the higher the index, the greater the density of reflective particles, and these zinc oxide and titanium dioxide may hinder the normal breathing of the skin. It's like you put a layer of tin foil on your face, do you think your skin will be uncomfortable.

The reason why chemical sunscreen works is because the chemical components in it can interact with ultraviolet rays and then be absorbed and metabolized by the skin. Therefore, it is well understood that the higher your SPF, the more chemical you apply to your skin. more ingredients. And these ingredients are more or less harmful to the skin. So, "just right" is actually the key. Even in the summer when the sun is the strongest, I only use SPF30+, it will not be higher! If you are afraid that the sunscreen effect is not enough, you will use other physical methods to assist, such as wearing sunglasses and hats.

Do you really need sunscreen in your home?

Some experts may suggest that you also apply sunscreen indoors, because UV rays can penetrate glass. But in fact, I have consulted friends who are majoring in physics, and experiments have shown that how much ultraviolet rays can be blocked by glass actually has a lot to do with the "glass" itself. At present, the general residential building glass must first exceed a certain thickness, and use more advanced materials to ensure the absorption of various light and the balance of thermal energy. Very little UV light can penetrate this glass. General glass can block most of UVB, but UVA can penetrate, but, for modern residential glass, it also has a considerable blocking effect on UVA.

For example:

The glass of the car is usually thinner, so if your car does not have a special anti-ultraviolet film, then you are likely to get sunburned and tanned in the car under direct sunlight. However, in the house, if you do not deliberately stand When the glass is exposed to direct sunlight, the ultraviolet rays that can actually damage the skin are very limited. Therefore, I personally never apply sunscreen at home, because I usually apply it every day at work, and at home on weekends, it is also necessary to give the skin a chance to breathe and rest for a day or two.

How to choose?

The smaller the SPF value, the worse the sun protection effect; the larger the SPF value, the better the sun protection effect.

PA + represents a maintenance effect, PA +++ represents a good maintenance effect.

PFA 2-4 is mild sunscreen, the effective protection time is 2-4 times, and so on.

Time multiplier for skin to resist UVB (medium-wave erythema-effect ultraviolet light) Exposure to long-wave UVA (long-wave dark-spot effect ultraviolet) in sunlight The degree of solar heat (near-infrared) reflection of sunlight (%)

The sunscreen products in Australia and New Zealand are great!

The ozone hole over Antarctica has alarmed the UV index in Australia and New Zealand almost every year. Therefore, in Australia and New Zealand, the number of skin cancer deaths is particularly high every year. So naturally, the sunscreen products in Australia and New Zealand also have higher standards and requirements for sunscreen effects.

A friend went to the beach to play, and bought a gold bottle with SPF50+ from Shiseido Anessa, Japan. Who would have thought that he would run like a crazy beach all day, and it would be a tragedy when he returned to the hotel at night. . . The skin was red and itchy, and it was uncomfortable. Later, I had to put the mineral water in the refrigerator and put it on my arms and legs, so that I could barely fall asleep. Later, the next day, I changed to the 1L COLES sunscreen in the Australian supermarket, but I didn't get sunburned! I have to sigh that Japanese sunscreens are simply "weak" under the ultraviolet rays on the coast of Australia!

I believe many people also agree that the sunscreen applied to the body is actually easy to say, but the difficulty is how to choose "face" sunscreen products. The facial skin is more sensitive than the body, and because makeup is applied after application, there are higher requirements for the texture of sunscreen, etc.

Apply sunscreen to your face, first, not too greasy! Second, it must fit the skin and apply makeup without affecting the makeup! If a sunscreen can't meet these two requirements, I don't think I will consider using it on my face no matter how good the sunscreen is!

Seasonal sun protection

Spring

1. In spring, the sun is relatively soft. You can choose a sunscreen with an ordinary sun protection factor. Generally, about SPF15 is enough.

2. In addition to sunscreen, you can also try sunscreen.

Summer

1. Reapply sunscreen

Sweating or wiping with a towel will reduce the sunscreen effect. Repeated application is not to get new protection, but to maintain the sunscreen effect. Any skin care product, even just water, will affect the function of the sunscreen as long as it is covered on the sunscreen, so it is necessary to reapply the sunscreen after swimming or sweating.

2. Avoid going out at noon

In summer, when the intensity of ultraviolet radiation in the sun is at its highest from 10 am to 2 pm every day, you should avoid or reduce going out.

3. Use sunscreen

The protection of sunscreen depends not only on the level of sunscreen ingredients and factors, but also on the thickness and uniformity of wiping.

Seasonal sun protection

Autumn

1. Pay attention to your diet, eat more fruits and vegetables and other sunscreen nutrients.

2. Choose the right sunscreen.

3. Pay attention to repair after sun exposure.

Smearing matters

Half an hour before going out,Apply sunscreen evenly to all parts of the skin, and the amount should not be too small. To reapply sunscreen. The effectiveness of sunscreen has a certain period of time. In summer, the weather is hot, it is easy to sweat, and it is easy to wash off the sunscreen, so the work of reapplying is very important. After swimming, you should always dry off the water and reapply sunscreen. When doing outdoor sports, you need to reapply every 3 hours.

Sunscreen mistakes

Myth 1: UV rays are only very strong at very hot temperatures.

Reality: UV rays do not feel hot. For example, when people climb a mountain, the higher the altitude, the stronger the ultraviolet rays. The mountain wind blows very cool, but the ultraviolet rays are already strong. For every 1000 meters up, the UV light increases by 10%. The same is true at sea: the sea breeze keeps you cool, but the UV rays are already extremely strong.

Sunscreen Mistakes

Myth 2: When the clouds are thick on cloudy days, the UV rays will not harm the skin.

Reality: Clouds have almost no shielding effect on ultraviolet rays, 90% of ultraviolet rays can penetrate the clouds, and only dark and thick rain clouds can block some of the ultraviolet rays.

Myth 3: The higher the SPF of a sunscreen product, the more beneficial it is to the skin.

Real situation: Products with higher SPF mean that more sunscreen agents are added, and the greater the irritation to the skin, so if you usually go to work, you can choose SPF15 and PA+ products. If you are exercising outdoors, you should choose products with SPF25~SPF35 and PA++. If you are swimming at the beach, choose SPF35~SPF50, PA+++.

Misunderstanding 4: Sunscreen can produce sunscreen protection after being applied.

Real situation: Since the active ingredients in the sunscreen must penetrate into the stratum corneum surface to exert a long-term protective effect, it must be wiped 30 minutes before going out, and replenished once before going out. At least 1-2 ml each time is required to achieve the best sunscreen effect.

Misunderstanding 5: Forgetting to apply sunscreen occasionally will not have much impact on the skin.

Real situation: Sun exposure can be accumulated, so although it is only indirectly exposed to sun exposure, the damage to the skin will accumulate for a long time, and the consequences may not be immediately visible, but it will cause skin tanning and facial tanning over time. Spots, loss of skin elasticity, wrinkles, and aging appear on the skin.

Myth 6: As long as you put on sunscreen before going out, your skin will be safe all day long

Real situation: After a sunscreen product is applied on the exposed area for several hours, its sunscreen effect will gradually weaken due to the dilution of sweat and other reasons, so it should be washed off and reapplied in time to ensure the continuation of the sunscreen effect.

Myth 7: My skin is already tanned, and putting on sunscreen won't help.

Real situation: The skin turns brownish yellow after sun exposure, indicating that the skin has entered a state of self-protection. The thickening of the skin and the production of melanin are the manifestation of the skin's self-protection. However, melanin can only partially absorb ultraviolet B, and it acts as an isolation, so that the skin is not damaged, but it does not have the function of absorbing ultraviolet A. Therefore, when outdoors, the isolation barrier between the sun and the skin is essential.

Misunderstanding 8: I have already used a lotion and foundation that have both sun protection value, so the sun protection effect should be the combination of the two.

Reality: You only get sun protection from the product with the higher SPF, so you don't need to use two sunscreens at the same time.

Misunderstanding 9: Playing a parasol can shade the sun

In fact, 50% of ultraviolet rays can pass through the isolation of parasols and harm the human body; the same is true for glass, which can only isolate medium-wave ultraviolet (UVB), and long-wave ultraviolet (UVA) will penetrate glass without any obstruction, so sitting Sunscreen is also required indoors.

Physical sunscreen, chemical sunscreen, biological sunscreen

Sunscreen products are mainly divided into physical sunscreen, chemical sunscreen, and biological sunscreen. Most of the physical sunscreens are mineral powders, which build a "Great Wall" outside the skin to block sun damage, but the products will be greasy and can only block UVB. And UVA is blocked by chemical sunscreen, while chemical sunscreen needs to first enter the skin, combine with cells, and then neutralize the oxygen free radicals entering the skin. 

Because it must enter the skin, some chemical sunscreen ingredients can cause allergies. For sensitive skin, it is safer to choose physical sunscreen, but most skin will choose chemical sunscreen to be more refreshing and comfortable. Biological sunscreen uses plant extracts to soothe and calm the skin, while protecting and repairing after sun exposure.