| 摘要 |
<p>Minute capsules having a wall of water-insoluble polymer material enclosing and retaining a particle of solid material are produced by forming a solution of a first polymer material intended to form the wall of the capsule, dispersing in said solution minute particles of the solid material, adding with agitation a second polymer material incompatible with the first thereby inducing the first polymer to separate out and deposit on each solid particle individually to form an encapsulating liquid wall thereon, and finally hardening the wall material. In an example, ammonium nitrate (to be used for example in explosives or fertilisers) is suspended in a solution of ethyl cellulose in 80/20 toluene/ethanol, a liquid polybutadiene is added to precipitate a strongly alcoholic solution of ethyl cellulose around the particles of ammonium nitrate, and toluene diisocyanate is then added to react with the ethanol and form a hard shell around each particle. The process may also be applied to potassium dichromate, metal hydrides, and stannous fluoride. Other filmforming polymers which may be used are cellulose nitrate and polymethyl methacrylate; plasticizers such as dimethyl, dibutyl or dioctyl phthalates, castor oil and nitrated glycols may be included.ALSO:Ammonium nitrate to be used in fertilizers is suspended in a solution of ethyl cellulose in 80/20 toluene/ethanol, a liquid polybutadiene is added to precipitate a strongly alcoholic solution of ethyl cellulose around the particles of ammonium nitrate, and toluene diisocyanate is then added to react with the ethanol and from a hard shell around each particle. Other film-forming polymers which may be used are cellulose nitrate and polymethyl methacrylate; plasticizers such as dimethyl, dibutyl or dioctyl phthalates, castor oil and nitrated glycols may be included.ALSO:Minute capsules having a wall of water-insoluble polymer material enclosing and retaining a particle of solid material are produced by forming a solution of a first polymer material intended to form the wall of the capsule, dispersing in said solution minute particles of the solid material, adding with agitation a second polymer material incompatible with the first, thereby inducing the first polymer to separate out and deposit on each solid particle individually to form an encapsulating liquid wall thereon, and finally hardening the wall material. Other film-forming polymers which may be used are cellulose nitrate and polymethyl methacrylate; plasticizers such as dimethyl, dibutyl or dioctyl phthalates, castor oil and nitrated glycols may be included.</p> |
