Patent ID: 8563633

Claim:
A compound comprising: a lignophenol derivative having a weight average molecular weight in a range of 6000-8,500, and satisfying the following formula (1): 3.0≦pH value≦4.5 (1) wherein the pH value is a determined value for a liquid mixture containing 0.2 g of the lignophenol derivative added to 40 ml of pure water, wherein: the lignophenol derivative is represented by the following formula (3): wherein in formula (3), X 1 , X 2 , and X 3 each independently represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted arylene group, a hydroxyl group, a carboxyl group, an amino group, or an amide group, a and c each independently represent an integer of from 0 to 3, b represents an integer of from 0 to 4, and n represents an integer of from 10 to 28.