Peanut skin tannin

For the preparation of the peanut skin tannin, the red skins were separated from residual nut and hull material by hand sorting, and then about 30 lb of skins were extracted with acetone-water (60 40 v/v) at a liquor-to-skins ratio of 5 to 1 at 50 °C for 4 hr in a stainless steel tank. The extract was filtered through a fiberglass mat, the acetone was removed under vacuum on a rotary evaporator, and the aqueous solution was freeze-dried. 

The sulfite extract performed nearly as well as the peanut skin tannin in bonding to nylon. Use of a tannin sulfonate derivative does not seem to hinder the development of strong bonds (compare peanut skin and sulfite extracts from pine bark). Likewise, the presence of carbohydrates in the tannin extracts does... 

Figure 2. Pullout forces of polyester cords for various tannin-containing adhesive dips as a function of percent resorcinol. 1, pecan pith sulfite extract 2, purified pine bark tannin 3, pine bark sulfite extract 4, peanut skin tannin.

Figure 7. Comparison of the pullout forces of polyester and nylon cords for dips containing peanut skin tannin.

Four types of condensed tannins were studied in the adhesive dips 1) extracts from pecan nut pith obtained by digestion with aqueous sodium sulfite-sodium carbonate solutions, 2) purified tannins from southern pine bark, 3) extracts from southern pine bark obtained by digestion with aqueous sodium sulfite-sodium carbonate solutions, and 4) tannins extracted with acetone-water solutions from peanut skins. 

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