DE9301250U1 - Solid sunscreen for optimal skin tanning - Google Patents

Description

1
Solid sunscreen for optimal skin tanning

Reports of an increasing number of chronic skin damages, mostly associated with the dermatological consequences of the ozone hole, lead to an increasing use of sunscreens with a high sun protection factor.

High sun protection factors for topical sunscreens can only be achieved with high absorber concentrations. At these concentrations, the absorbers can be detected in the peripheral bloodstream after a relatively short time. Due to the possible local and systemic toxic effects, topical sunscreens with high absorber concentrations are therefore not without problems.

A sensible solution is to use a solid-state sunscreen whose absorbers do not cause toxic reactions even when they come into contact with the skin. The absorbers are therefore embedded in plastic, which is available in the form of panels, films, fleeces, fabrics or paints.

This solution has been used in various ways so far, with the sun protection factor (erythema factor) being taken into account as criteria for the protective effect and the direct pigmentation for the tanning effect.

However, due to our own extensive photobiological experiments and calculations, it became clear that direct pigmentation, which usually fades after several hours, is not a reasonable criterion for permanent pigmentation. The same applies to information that only refers to spectral transmission without the associated photobiological effects.

The invention solves the problem of how a solid-state sunscreen must be designed in order to, on the one hand, achieve an appropriate protective effect against acute (and chronic) skin damage and, on the other hand, to maintain permanent pigmentation.

The object is achieved according to the invention in such a way that the sun protection factor (erythema factor) for normal skin types is at least 15, while the weakening factor for permanent pigmentation (pigmentation factor) is at most 6.

This makes it possible to receive less than a threshold dose for erythema (= minimum erythema dose MED) even under extreme sun exposure between 9 a.m. and 3 p.m. local time, while at the same time receiving more than a threshold dose for permanent pigmentation (= minimum pigmentation dose MTD). To be on the safe side, it was assumed that the person being irradiated did not turn around during these 6 hours (in which around 75% of the erythema-effective daily dose was received), so that the entire erythema-effective dose was applied to one side of the body. For permanent pigmentation, it was realistically assumed that this radiation was evenly distributed over both sides of the body.

The solid-state sunscreen delays desired and undesired photobiological reactions. The factor (F _biol ) by which the reaction is delayed is defined as follows:

JE(A) ₆ · s(A) _biol · dA A ₁

F _biol A ₂

/ E(A) ₆ . s(A) _biol . &tgr;(&lgr;) . dA A ₁

mean

A ₁ lower wavelength limit

A ₂ upper wavelength limit

E(A) ₆ spectral irradiance of global radiation

&tgr;(&lgr;) spectral transmission of the

Solid sunscreen

relative spectral sensitivity of human

3 Skin for the photobiological reaction

the following indices mean

UV-induced erythema in people with normal skin reaction

pp UV-induced permanent pigmentation in humans

with normal skin reaction ca UV-induced skin cancer el UV-induced skin aging pi UV-induced direct pigmentation (immediate

pigment darkening), in people with normal

Skin reaction.

The important parameters are: 15

the erythema factor

400 nm / ε(λ) _β · s(A) _er · dX 290 nm

400 nm J ε(λ). · s(X) _ST . &tgr;(&lgr;) · dX 290 nm

the pigmentation factor 30

400nm

/ ε(λ _{) β -} 3 _{(λ) �rgr;�rgr;} . dX 290 nm

F _pp =

400nm

J ε _{(λ) β} . s(A) _pp . &tgr;(&lgr;) . dX 290 nm

the average transmission of 290 - 330 nm

330nm

J τ(λ) · dX 290 nm

_X1 =

40

4
and the average transmission of 330 - 400 nm

4 00 nm

/ &tgr;(&lgr;) · &aacgr;&lgr;
330nm

&khgr; -

70

The relationship between the parameters is as follows

5,219 5,025

^ ₂ =
15

F
^r pp ] - oh, 057 &tgr;? 1,422

First, the desired factors are specified and the value for T ₂ is determined with an accuracy of + 0.035 and the value for T ₁ with an accuracy of ± 0.015.

It must be taken into account

F _er > 15
_Fpp < 6

Values for T ₂ > 0.9 and T ₁ < 0 are not real.

From this, the previously determined transmission values T ₁ and T ₂ can then be adjusted experimentally or computationally using the Lambert-Beer law by varying the concentration of the known absorbing materials and the type and thickness of the substrate.

The following plastics in the form of sheets, films, fleeces, fabrics and lacquer layers are used as substrates for the solid-state sunscreen, which, depending on the modification, have sufficient transmission in the UV range: Acrylonitrile methyl methacrylate (AMMA), cellulose acetobutyrate (CAB), ethylene tetrafluoroethylene (ETFE),

Ethylene-vinyl acetate (EVA), polycarbonate (PC), polyethylene (PE, HDPE, LDPE), polyethylene terephthalate (PETP), polymethylene methacrylate (PMMA), polypropylene (PP), polytetrafluoroethylene (PTFE), polyurethane (PU), polyvinyl chloride (PVC).

The following materials are mainly used as absorbers for the solid-state sunscreen:

Benzophenones, benzotriazoles, compounds of salicylic, cinnamic and oxalic acid as well as compounds resulting from the modification of these substances.

The dyes for the solid-state sunscreen according to the invention must have a high transmission, especially in the range from 330 to 400 nm. These are primarily violet, red-violet and blue soluble dyes as well as organic and inorganic pigments.

The desired transmission values T ₁ and T ₂ are determined using the following equations

&tgr;(&lgr;) = T(A) ₁ . R _f
25

away

&tgr;(&lgr;)&khgr;,x = T(A) ₁ , _b
T(A) = T(A) _i>s . T(A) _1)A . T(A) _liF · R _f

T(A) ₁ spectral pure transmission
R _f reflection factor of the substrate

^T (^)i,b spectral pure transmission with known layer thickness

or concentration

&tgr;(&lgr;) _1>&khgr; spectral pure transmission at desired layer thickness or concentration

^&tgr; (&lgr;)&igr;, ₃ spectral pure transmission of the substrate

^&tgr; (&lgr;)&igr;, _�Agr; spectral pure transmission of the absorber or

Absorber ■u(A) _i)F spectral pure transmission of the dye or

Dyes 5

The following table shows examples with different predefined erythema factors (F _er ), combined with different predefined pigmentation factors (F _pp ) and the resulting mean transmission values (T ₁ ) in the spectral range 290 to 330 nm and the mean transmission values (τ ₂ ) in the spectral range 330 to 400 nm.

Fer ^F PP T &tgr; ₂ 10 6 0.121 0.367 10 5.5 0.117 0.446 10 5 0.111 0.541 10 4.5 0.105 0.657 10 4 0.096 0.802 10 3.7 0.091 0.900 15 6 0.064 0.534 15 5.5 0.060 0.614 15 5 0.054 0.709 15 4.5 0.048 0.825 15 4.2 0.044 0.900 20 6 0.036 0.619 20 5.5 0.031 0.698 20 5.0 0.026 0.793 20 4.5 0.020 0.900 25 6 0.019 0.669 25 5.5 0.014 0.748 25 5 0.009 0.843 25 4.7 0.005 0.900 30 6 0.007 0.702 30 5.5 0.003 0.781 30 5.0 < 0 0.876 30 4.9 < 0 0.900 35 6 0.006 0.726 35 5.5 < 0 0.805 35 5.0 < 0 0.900

40 6 < 0 0.744

Before the filing date, the following solid sunscreens were on the market:

brand

Sunselect
Nylex
Solmax
Sunselect
Sunselect

Sunselect
Mutzhas
Mutzhas
Procutis
Mutzhas

Mutzhas
Procutis
Procutis

material

PVC

PVC

PVC

PVC

PVC

PVC

P.E.

PMMA

PVC

PVC

PVC (grid) violet

PVC Purple

PVC Blue

Colour T ₁

Violet 0.144

Violet 0.038

Violet 0.016

Light blue 0.019

Pink 0.012

Blue 0.011

Yiollett 0.008

Violet Colorless Violet

<0.001
<0.001
<0.001
<0.001
<0.001
<0.001

0.632
0.510
0.506
0.337
0.406
0.409
0.433
0.485
0.476
0.398
0.366
0.311
0.256

Fer

7.9

40

41

43

51

52

None of these known solid-state sunscreens meets the criteria of this invention.

The following solid-state sunscreens according to the invention were manufactured in-house:

Mutzhas P.E. Colorless 0.060 0.614 15 5.5 Mutzhas P.E. Violet 0.064 0.534 15 6.0 Mutzhas PVC Colorless 0.054 0.709 15 5.0 Mutzhas PVC Violet 0.060 0.614 15 5.5 Mutzhas PMMA Colorless 0.048 0.825 15 4.5 Mutzhas PMMA Violet 0.054 0.709 15 5.0

A solid sunscreen according to the invention with an erythema factor F _er > 15 and a pigmentation factor F _pp < 6 shows:

The skin ageing factor F _el is about 0.8 · F _ec and the

Skin cancer factor F _n

is about 1.1 · F _er . Thus, the protection

against these chronic skin damages is about the same as

protection against the acute skin damage caused by sunburn. The threshold time for direct pigmentation, which fades again after a short time, is about half as long as the threshold time for permanent pigmentation. If it is intense, permanent pigmentation can result in the body's own erythema (protection) factor of a maximum of 8.

If the erythema (protection) factor of the solid sunscreen is 15 or just above, on the one hand a very high level of sun protection is achieved, on the other hand enough short-wave UV radiation in the range of up to 330 nm is allowed through to achieve a thickening of the epidermis (light callus). This light callus can achieve an additional endogenous erythema factor of a maximum of 4.

15 will be.

The solid sunscreen according to the invention can thus build up sufficient natural protection against erythema without the skin being affected by excessive daily doses of harmful UV radiation.

Some practical examples are given below:

25 Example 1

Three-layer film produced by coextrusion with

following structure 1. Top layer: 30 2. Core:

3. Top layer: F _er = 15

F _pp = 5.5 X ₁ = 0.06 40 τ ₂ = 0.61

20 um EVA 160 um LDPE (which contains about 10% masterbatch containing the UV absorbers and the violet dye). 20 um EVA

Example 2

Film produced using the calendering process with the following structure: 5

Thickness: 0.3mm

Substrate: colourless soft PVC, in which the

organic absorber.

F _er = F _pp = 5.0

T ₁ = 0.05 15 X ₂ = 0.71

Example 20 Cast plate made of PMMA

Thickness: 5 mm Substrate: PMMA stabilized in which the colorless organic absorbers are dissolved.

F _er = 30

_Fpp = 4.5

_T1 = 0.05 _T2 = 0.83

The solid sunscreen according to the invention is used, for example, in the following form:

Umbrellas, awnings, tents, roofs, canopies, coverings, awnings, clothing, hats, caps, visors as well as coverings and coverings for animals with thin hair or feathers.

Claims (2)

Expectations 1. Solid sunscreens characterised by the following features: (a) the erythema factor (F _er ) is at least 15 and not more than 4 0 (b) the pigmentation factor (F _pp ) is at least 4 and not more than 6. 2. Solid sunscreen according to claim 1, characterized by a) an average transmission (τ ₂ ) in the spectral range up to 400 nm of 5,219 5,025 T, = F F b) an average transmission (T ₁ ) in the spectral range up to 330 nm of 1.422 T ₁ = - 0.057 · T ₂ .