Light screening compositions

Details Light screening compositions Light screening compositions

1997-04-16

2001-02-27

Moore, Margaret G. (Department: 1712)

Drug, bio-affecting and body treating compositions

Topical sun or radiation screening, or tanning preparations

C424S070900

Reexamination Certificate

active

06193959

ABSTRACT:

The invention relates to photostable, cosmetic light-screening compositions for the protection of the human epidermis and the hair against the ultraviolet rays of wavelengths between 290 and 400 nm.
In particular, it relates to such compositions which comprise, in a cosmetically acceptable vehicle containing at least one fatty phase, about 0.5 to about 5%, in particular about 1 to about 4% by weight, of a dibenzoylmethane type UV-A screening agent and at least about 0.1% to about 20%, in particular about 0.5 to about 15% by weight, of a polymer UV-B filter of the benzylidene malonate silicone type exhibiting an organosiloxane having at least one unit of the general formula
wherein the radical
is either bound to the C
&agr;
atom and the radical
is bound to the C
&bgr;
atom of the double bond in (I′) or in the corresponding single bond in (II′), or vice versa, any other units present in the said siloxanes being those represented by the general formula
wherein R represents a C
1-8
alkyl or an aryl group, R
1
is a hydrogen atom or a C
1-5
alkyl group, R
2
is a hydrogen atom, a C
1-5
alkyl group or a group OR
1
, R
3
is a C
1-5
alkyl group, R″ represents a hydrogen atom, a monovalent C
1-8
hydrocarbon or halogenated hydrocarbon group, a has a value of 0, 1 or 2, b has a value of 0, 1, 2 or 3 and n has a value of from 1 to 6, provided that the
groups and the two R
2
groups are linked to the aromatic ring (C
6
. . . ) at the para- and both meta-positions in relation to the group —CH═C[C(O)OR
3
]
2
, and the two vertical strokes designate either the alkylene derivative
or the alkylidene derivative
in case of formula (I′), or the saturated derivative with a linear chain
or the saturated derivative with a branched chain
in case of formula (II′), the weight ratio of the silicone to the dibenzoylmethane derivative being not less than about 0.1, preferably not less than about 1.0, and not more than about 25, preferably not more than about 8 to 10.
An alternative designation for the subject matter of compounds I′ and II′ is thus
wherein
Formula I encompasses thus, as pointed out above, the alkylidene derivative Ia and the alkylene derivative Ib:
The preparation and the properties of these benzylidene malonate silicone types are described in WO 92/20690 of Nov. 26, 1992.
The ratio of the alkylene to the alkylidene derivative is not critical, and is normally between about 5- about 50%:about 95-50% w/w, in particular about 20-30:80-70% w/w, or in the case of the saturated derivatives, the linear derivative is the predominant derivative.
Formula II encompasses the saturated linear (IIa) and saturated branched (IIb) derivatives:
The preparation and properties of such benzylidene malonate silicone compounds is described in EP 358 584 (U.S. Pat. No. 5,053,290) and FR 2 642 967-A1 (U.S. Pat. No. 5,415,854).
The suitable dimensions for the various parameters of the definition of the above captioned formula III are equally derivable from WO 92/20690. Thus, in the general formulae I and II the radicals can be defined as follows:
R may be for example methyl, ethyl, butyl or phenyl.
R″ is hydrogen or a monovalent hydrocarbon or halogenated hydrocarbon group having up to 8 carbon atoms, for example alkyl, alkenyl, aryl, alkaryl, aralkyl and also halogen substituted alkyl, alkenyl, aryl, alkaryl and aralkyl are such groups. Particular examples include methyl, ethyl, vinyl, phenyl, tolyl, ethylphenyl, dimethylphenyl, benzyl, phenethyl and 3,3,3-trifluoropropyl, etc.
R
3
denotes alkyl groups having up to 5 carbon atoms, as for example methyl, ethyl, propyl, isopropyl, butyl, secondary butyl, isobutyl, pentyl and neopentyl, etc.
Examples for the C
1-5
alkyl radicals of R
1
and R
2
are as given above. Suitable radicals OR
1
are methoxy, ethoxy, propoxy, isopropoxy, etc. From the above listing, it can also be deduced that the alkyl and the alkoxy radicals may in the present context represent straight-chain and branched radicals.
It is preferred that at least 80% of all R and R″ groups are methyl groups, most preferably substantially all R and R″ groups are methyl groups. It is also preferred that R
1
is either hydrogen, methyl or ethyl, most preferably hydrogen. Preferably each R
2
group is hydrogen or one R
2
group is a hydrogen, while the other one is an alkoxy group, preferably methoxy or ethoxy. R
3
is preferably methyl or ethyl. In addition, a is preferably 1 while b is preferably 2, making the organosilicon compound a substantially linear or cyclic diorgano-siloxane polymer. However, if the diorganosiloxane—see, e.g. Table 1, the second formula—is a substantially linear polymer at least two end blocking units must be present, thus requiring the presence of 2 units in which a has a value of 2, two units in which the value of b is 3 or one unit wherein a is 2 and one unit in which b is 3. n is preferably 1, 2 or 3. Suitable preferred polymers have therefore either the general formula
wherein R and R″ are as defined above, X denotes a group Y or a group R″ and Y denotes an alkylene group of the formula
—C(R
1
)═CH—(CR
2
1
)
n
—O—C
6
R
2
2
H
2
—CH═C—[C(O)OR
3
]
2
or the corresponding alkylidene derivative in case of formula (I), or, in case of formula (II), one of the groups
—CR
2
1
—CHR
1
—(CR
2
1
)
n
—O—C
6
R
2
2
H
2
—CH═C—[C(O)OR
3
]
2
,
or
In the above captioned formulae, r has a value of from 0 to 130, s has a value of from 0 to 20, whereby at least one X denotes Y in the case that s=0; t has a value of from 0 to 10, v has a value of from 1 to 10 and v+t has a value of at least 3, and R
1
, R
2
and R
3
are as above.
In the substituent Y of the organosilicon compounds, the above captioned alkylene group
—C(R
1
)═CH—(CR
2
1
)
n
—O
or the corresponding above captioned alkylidene derivative, or the groups
may occupy the meta-position or the para-position of the aromatic ring (C
6
. . . ) in relation to the group —CH═C[C(O)OR
3
]
2
.
Preferably the para-position is thus occupied. The groups R
2
occupy the remaining two positions out of the para- and meta-positions in relation to the group —CH═C[C(O)OR
3
]
2
. Examples of preferred substituents Y thus include
or the corresponding alkylidene derivatives, or the saturated linear structures, such as:
or the corresponding saturated branched derivatives, namely those carrying the structure
The material organosilicon compounds have at least one unit falling within the general formulae (I) or (II), preferably at least 2. Suitable organosilicon compounds are polymeric materials which may be homopolymers consisting only of such units (I) or (II), or they may be copolymers containing both units (I) or (II) and units having the general formula (III). The organosilicon compounds may vary from freely flowing liquids to highly viscous gum-like materials or resinous solids. Preferred, at least for cosmetic applications, are the liquid substantially linear organosiloxane homopolymers and copolymers, for example those having a viscosity (in c St) of from 100 to 20000 mm
2
/s, more preferably 500 to 5000 mm
2
/s as these are more easily mixed with other ingredients to make cosmetic compositions and as they will spread more easily onto the skin.
Organosilicon compounds which are especially preferred are those wherein the number of units (I) or (II) is limited to a maximum of 20% to 25% of the total number of siloxane units in the molecule. For maximum efficiency in its U.V. absorbing property it is preferred that the number of units (I) or (II) be limited to 10% to 12% or less of the total. The units of formula (I) or (II) may be distributed randomly in an organosiloxane polymer, they may be end-blocking units of the polymer or they may be located at the end of the poly-mer and pending in chain of the polymer at the same time. Units of the general formula (I) or (II) are conveniently situated at the end of the organosiloxane polymer forming one or more endblocking uni

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