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Image Number 19 for United States Patent #7785636.
A first subject of the present invention is an insoluble powder characterized in that a zeta-potential is a negative value.It is preferable that barium sulfate is a main ingredient in the insoluble powder.It is preferable that an average primary particle diameter is 3 to 100 .mu.m, and an aspect ratio is 3 to 250 in the insoluble powder.It is preferable that the insoluble powder is a metal-doped barium sulfate powder obtained by reacting a barium ion and a sulfate ion in the presence of a metal ion.It is preferable that the metal ion is one or more selected from the group consisting of a lithium ion, a sodium ion and a zinc ion in the insoluble powder.A second subject of the present invention is a skin barrier function recovering powder, or a skin roughening preventing and improving powder, which comprises the aforementioned powder.A third subject of the present invention is a skin external composition characterized in that a content of the aforementioned powder is 1 to 40% by weight.
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