Asymmetric stilbene compounds

Details Asymmetric stilbene compounds Asymmetric stilbene compounds

2000-09-08

2002-11-19

Gupta, Yogendra N. (Department: 1751)

Bleaching and dyeing; fluid treatment and chemical modification

Chemical modification of textiles or fibers or products thereof

C510S492000, C510S276000, C510S301000, C510S495000, C252S008630, C008S566000, C008S190000, C544S193200

Reexamination Certificate

active

06482241

ABSTRACT:

The present invention relates to new compounds, in particular to new asymmetric stilbene UV absorber compounds which are useful as sun protection agents; and to a method of improving the sun protection factor (SPF) of textile fibre material, especially cotton, polyamide and wool, comprising treating them with the new compounds.
It is known that light radiation of wavelengths 280-400 nm permits tanning of the epidermis. Also known is that rays of wavelengths 280-320 nm (termed UV-B radiation), cause erythemas and skin burning which can inhibit skin tanning.
Radiation of wavelengths 320-400 nm (termed UV-A radiation) is known to induce skin tanning but can also cause skin damage, especially to sensitive skin which is exposed to sunlight for long periods. Examples of such damage include loss of skin elasticity and the appearance of wrinkles, promotion of the onset of erythemal reaction and the inducement of phototoxic or photoallergic reactions.
Any effective protection of the skin from the damaging effects of undue exposure to sunlight clearly needs to include means for absorbing both UV-A and UV-B components of sunlight before they reach the skin surface.
Traditionally, protection of exposed human skin against potential damage by the UV components in sunlight has been effected by directly applying to the skin a preparation containing a UV absorber. In areas of the world, e.g. Australia and America, which enjoy especially sunny climates, there has been a great increase in the awareness of the potential hazards of undue exposure to sunlight, compounded by fears of the consequences of alleged damage to the ozone layer. Some of the more distressing embodiments of skin damage caused by excessive, unprotected exposure to sunlight are development of melanomas or carcinomas on the skin.
One aspect of the desire to increase the level of skin protection against sunlight has been the consideration of additional measures, over and above the direct protection of the skin. For example, consideration has been given to the provision of protection to skin covered by clothing and thus not directly exposed to sunlight.
Most natural and synthetic textile materials are at least partially permeable to UV components of sunlight. Accordingly, the mere wearing of clothing does not necessarily provide skin beneath the clothing with adequate protection against damage by UV radiation. Although clothing containing a deeply coloured dye and/or having a tight weave texture may provide a reasonable level of protection to skin beneath it, such clothing is not practical in hot sunny climates, from the standpoint of the personal comfort of the wearer.
There is a need, therefore, to provide protection against UV radiation for skin which lies underneath clothing, including lightweight summer clothing, which is undyed or dyed only in pale shades. Depending on the nature of the dyestuff, even skin beneath clothing dyed in some dark shades may also require protection from UV radiation.
Such lightweight summer clothing normally has a density of less than 200 g/m
2
and has a sun protection factor rating between 1.5 and 20, depending on the type of fibre from which the clothing is manufactured.
The SPF rating of a sun protectant (sun cream or clothing) may be defined as the multiple of the time taken for the average person wearing the sun protectant to suffer sun burning under average exposure to sun. For example, if an average person would normally suffer sun burn after 30 minutes under standard exposure conditions, a sun protectant having an SPF rating of 5 would extend the period of protection from 30 minutes to 2 hours and 30 minutes. For people living in especially sunny climates, where mean sun burn times are minimal, e.g. only 15 minutes for an average fair-skinned person at the hottest time of the day, SPF ratings of at least 20 are desired for lightweight clothing.
It is already known, e.g. from WO 94/4515, that the application of specified types of UVA to a light-weight textile materials in general can effect an increase in the SPF value of the textile so treated. The increase in SPF value achieved thereby, however, is relatively modest.
The use of fluorescent whitening agents (FWAs) in order to effect an increase in the SPF value of textiles has also been proposed. Most FWAs, however, are only effective in absorbing radiation in the UV-A range. Certain symmetric FWAs have been disclosed in EP-A728,749 which absorb radiation in both the UV-A and UV-B ranges, and impart greatly increased SPF ratings to textile fibre materials treated with them.
In Chem.Abstracts, 1962, 12913a (Japan 14,728), there are described certain asymmetric FWAs, but these known compounds have no UV-B absorbing properties so that they are not able to impart useful SPF ratings to textile materials treated with them.
Certain new asymmetric stilbene UV absorber compounds have now been found which, relative to known symmetric stilbene UV absorber compounds, are easy to formulate and impart both excellent whiteness levels and SPF ratings to textile materials treated with them.
Accordingly, the present invention provides, as a first aspect, an asymmetric compound having the formula:
in which M is hydrogen, an alkali metal atom, ammonium or a cation formed from an amine; Xa and Xb are the same or different and each is NH
2
; NH(C
1
-C
4
alkyl); N(C
1
-C
4
alkyl)
2
; NH(C
2
-C
4
alkoxyalkyl); N(CH
2
CH
2
OH)
2
; a group NH—Z—NR
1
R
2
in which Z is C
2
-C
14
alkylene or optionally substituted arylene, and R
1
and R
2
are the same or different and each is C
1
-C
12
alkyl or R
1
and R
2
, together with the nitrogen atom to which they are each attached, form a morpholino, piperidino or piperazino ring; an aminoacid residue; C
1
-C
4
alkoxy; hydroxy-substituted-C
2
-C
4
alkoxy;
and
Ya and Yb are the same or different and each is a substituted amino group having both UVA and UVB-absorbing properties, preferably a group having the formula:
in which R
3
is CN; SO
2
R
5
which R
5
is, C
1
-C
12
alkyl, C
1
-C
12
alkoxy, NH
2
, NH(C
1
-C
4
alkyl), N(C
1
-C
4
alkyl)
2
, N(CH
2
CH
2
OH)
2
, C
1
-C
4
alkoxy or hydroxy-substituted-C
2
-C
4
alkoxy; COR
5
in which R
5
has its previous significance; COOM in which M has its previous significance or NHCOR
5
in which R
5
has its previous significance and
R
4
has the same significance as R
3
or is H, OH, C
1
-C
4
alkyl or C
1
-C
4
alkoxy; and one of Xa and Xb can be identical to one of Ya and Yb, provided that one of Xa and Xb is different from the other and/or one of Ya and Yb is different from the other.
Preferably, M is hydrogen, sodium, potassium, calcium, magnesium, ammonium, mono-, di-, tri- or tetra-C
1
-C
4
alkylammonium, mono-, di-, tri- or tetra-C
1
-C
4
hydroxyalkylammonium, or ammonium that is di- or tri-substituted with a mixture of C
1
-C
4
alkyl and C
1
-C
4
hydroxyalkyl groups. Preferably, each M is sodium.
When one or more of Xa, Xb and R
5
are NH(C
1
-C
4
alkyl), examples of such groups are NH-ethyl, NH-n-propyl, NH-isopropyl, NH-n-butyl and, in particular, NH-methyl groups.
When one or more of Xa, and Xb are NH(C
2
-C
4
alkoxyalkyl), examples of such groups are ethoxyethyl, methoxypropyl and, in particular,methoxyethyl.
When one or more of Xa, Xb and R
5
are N(C
1
-C
4
alkyl)
2
, examples of such groups are N(ethyl)
2
, N(n-propyl)
2
, N(isopropyl)
2
, N(n-butyl)
2
and, in particular, N(methyl)
2
groups.
When one or both of Xa and Xb is a group NH—Z—NR
1
R
2
, C
2
-C
14
alkylene groups Z include, e.g., ethylene, 1,3-propylene, 1,4-butylene, 1,5-pentylene, 1,6-hexylene, 1,8-octylene, 1,10-decylene, 1,12-dodecylene and 1,14-tetradecylene groups. Preferred are C
2
-C
6
alkylene groups Z, most preferably the 1,3-propylene group. Optionally substituted arylene Z include the naphthylene and, preferably, the phenylene group. The optionally substituted arylene Z may be substituted, for example with one or more C
1
-C
4
alkyl groups. C
1
-C
12
alkyl groups R
1
and R
2
may be, e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, n-octyl, n-decyl and n-dodecyl groups, pr

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