Cosmetic and personal care compositions

#The present invention relates to cosmetic and personal care compositions, such as hair styling compositions, containing block copolymers, and to their use in the treatment of hair.

#Cosmetic and personal care compositions such as hair styling sprays, mousses, gels, shampoos and conditioners, frequently contain resins, gums and adhesive polymers to provide a variety of benefits, for example, film-forming ability, thickening, sensory properties and hair shaping and setting.

#Polymers for use in such compositions are usually linear or graft homo- or co-polymers which contain various monomers in an alternating, random manner.

#The accompanying drawings illustrate, by way of example only, preferred embodiments of the invention.

#FIG. 1 is a plot showing SEC traces of an ABA copolymer which may be used in the compositions of the invention after polymerization of the midblock, and after addition of the endblocks to the midblock.

#FIG. 2 shows the in-phase (G′) and out-of-phase (G″) components of the complex rheological modulus G* as a function of frequency (ω) for a copolymer of DMA and MEA which may be used in a composition of the invention.

#The present invention involves the development of polymers for use in compositions for cosmetic and personal care applications. The compositions comprise a thermoplastic elastomer. The thermoplastic elastomer is a block copolymer comprising a core polymer having a backbone comprising at least a proportion of C—C (ie, carbon-carbon) bonds and two or more flanking polymers. The linkages in the backbone of the core polymer preferably comprise greater than 50%, more preferably greater than 75%, most preferably greater then 95%, such as, for example, at least 99% (these percentages being by number) C—C bonds. In some cases, the backbone may contain 100% (by number) C—C bonds. Other bonds which may be present in the backbone of the core polymer, in addition to the C—C bonds, include, for example, C—O bonds. The flanking polymers are bound to an end of the core polymer. Preferably, the flanking polymers comprise at least a proportion of C—C (ie, carbon-carbon) bonds. The linkages in the backbone of the flanking polymer preferably comprise greater than 50%, more preferably greater than 75%, most preferably greater then 95%, such as, for example, at least 99% (these percentages being by number) C—C bonds. In some cases, the backbone of the flanking polymer may contain 100% (by number) C—C bonds. Other bonds which may be present in the backbone of the flanking polymer, in addition to the C—C bonds, include, for example, C—O bonds.

#The core polymer can take a number of different forms. For example, the core polymer may be linear or star-shaped (the latter polymers also being termed “aerial”). Star-shaped polymers may have three or more arms. When the core polymer is linear, a flanking polymer is bound to each end of the core polymer and the resulting block copolymer is an ABA block copolymer; this is a preferred embodiment of the present invention. When the core polymer is star-shaped, a flanking polymer is bound to each end of the core polymer and the block copolymer therefore contains as many flanking polymers as there are points or free ends in the star shaped polymer. For example, if the star shaped core polymer has four ends the block copolymer will comprise four flanking polymer groups.

#Therefore, the block copolymer may have the structure (AB)n-Core, where A and B are polymeric blocks, n is 2 or more (preferably 2, or 4, 6, 8 or 12) and Core is a non-polymeric linking core. For ABA block copolymers, there may or may not be a non-polymeric core in the B block, depending on how polymerisation is carried out. In one preferred embodiment of the invention, the A and B blocks are each derived from a single monomer.