Production method for powdered hydrophilic modified polyrotaxane
The present invention aims to provide a method of producing a powdered hydrophilic modified polyrotaxane, which enables production of a powdered hydrophilic modified polyrotaxane excellent in storage stability in an industrially advantageous way. The present invention provides a method of producing a powdered hydrophilic modified polyrotaxane, comprising: a hydrophilic modification step of preparing a solution of a hydrophilic modified polyrotaxane by modifying all or part of hydroxy groups on a cyclodextrin of a polyrotaxane with hydrophilic modifying groups, the polyrotaxane containing the cyclodextrin, a polyethylene glycol included in the cavities of the cyclodextrin molecules in a skewered manner, and a capping group that is placed at each end of the polyethylene glycol and prevents dissociation of the cyclodextrin molecules from the polyethylene glycol; and a drying step of spraying the prepared solution of the hydrophilic modified polyrotaxane and drying the solution of the hydrophilic modified polyrotaxane in a heated gas stream.
1. A method of producing a powdered hydrophilic modified polyrotaxane, comprising:
a hydrophilic modification step of preparing a solution comprising a hydrophilic modified polyrotaxane that is formed by modifying all or part of hydroxyl groups on a cyclodextrin included in a polyrotaxane having hydrophilic modifying groups, a polyethylene glycol included in cavities of molecules of the cyclodextrin in a skewered manner, and a capping group that is placed at an each end of the polyethylene glycol and prevents dissociation of the cyclodextrin molecules from the polyethylene glycol; and
a drying step of spraying the prepared solution of the hydrophilic modified polyrotaxane and drying the solution of the hydrophilic modified polyrotaxane in a heated gas stream,
wherein the drying step is carried out in a spray dryer having an inlet temperature of the spray dryer in a range from 70° C. to 200° C. and an outlet temperature in a range from 55° C. to 105° C.
2. The method of producing a powdered hydrophilic modified polyrotaxane according to claim 1 ,
wherein the polyethylene glycol has a weight average molecular weight of 1,000 to 500,000.
3. The method of producing a powdered hydrophilic modified polyrotaxane according to claim 1 ,
wherein the drying step is carried out by blowing out at least two hot gasses having a temperature different from each other, from an inlet of the spray dryer.
4. The method of producing a powdered hydrophilic modified polyrotaxane according to the claim 1 ,
wherein pressure in a dryer system in the drying step is equal to or lower than an atmospheric pressure.