includes diester of rosin acid and propyleneglycol representative of formula iv the peak d includes the compounds expressed by the above formula i formula xi and formula xii it seems clear by comparing fig4 with fig5 that the production states of the peak c d and e are different particularly the peak area of c and d is large and the ratio of rosin acid part peak a is small in synthesis example 4 fig4 this suggests that the esterification to obtain the desired compounds proceeds effectively on the other hands in the view of the fact that the peaks of c and d are small and the detection start time of the peak e is before 1 40 10 minutes in the comparative synthesis example fig5 it is found that the expansion toward the higher molecular compounds is large and entirely different compounds are produced depending on the reaction conditions therefore diresinate of dihydric alcohol rosin and maleopimaric acid expressed by formula xi or formula xii is contained at the effective amount about more than 20 by weight in the neutral papermaking in synthesis example 4 but they do not reach the effective amount in comparative synthesis example 10 parts of ammonium salt of arylnonylphenol eo 9 mol added sulfate 45 parts of methacrylic acid 15 parts of n butylmethacrylate 25 parts of styrene 5 parts of u03b1 methylstyrene 2 parts of dodecylmercaptan 7 parts of sodium dodecylbenzenesulfate 350 parts of ion exchange water 10 parts of 10 of ammonium persulfate aqueous solution were mixed and agitated in the four neck flask for 1000 cc provided with an agitator a thermometer a reflux condenser and a tap funnel and they were kept at 85 u00b0 c for 5 hours and cooled to 50 u00b0 c then.