50results about How to "Low monomer content" patented technology

The invention provides methods of extracting a biodegradable polyester with a supercritical fluid effective to obtain a purified biodegradable polyester, such as a purified biodegradable poly(lactide-glycolide) (PLG). The supercritical fluid can be carbon dioxide at an elevated pressure, or can be carbon dioxide with one or more cosolvents. Methods for carrying out stepwise purification of the biodegradable polyester at multiple pressures or multiple temperatures, or both, are also provided. When the polyester is PLG, a purified PLG copolymer is obtained having a narrowed molecular weight distribution with respect to the unpurified polyester. The purified PLG copolymer can have a polydispersity index of less than about 1.7, less than about 2% monomers, and less than about 10% oligomers. The purified PLG copolymer can exhibit a reduced initial burst effect when incorporated into a controlled release formulation such as a flowable implant adapted to be injected into body tissues.

The invention provides methods of extracting a biodegradable polyester with a supercritical fluid effective to obtain a purified biodegradable polyester, such as a purified biodegradable poly(lactide-glycolide) (PLG). The supercritical fluid can be carbon dioxide at an elevated pressure, or can be carbon dioxide with one or more cosolvents. Methods for carrying out stepwise purification of the biodegradable polyester at multiple pressures or multiple temperatures, or both, are also provided. When the polyester is PLG, a purified PLG copolymer is obtained having a narrowed molecular weight distribution with respect to the unpurified polyester. The purified PLG copolymer can have a polydispersity index of less than about 1.7, less than about 2% monomers, and less than about 10% oligomers. The purified PLG copolymer can exhibit a reduced initial burst effect when incorporated into a controlled release formulation such as a flowable implant adapted to be injected into body tissues.

The process for the manufacture of an auto-oxidatively cross-linking hybrid polymer, in particular an aqueous hybrid polymer dispersion, comprises the step of reacting in a mini-emulsion process one or more ethylenically unsaturated monomers to form an addition polymer in the presence of a modified auto-oxidatively crosslinkable (AOC) polymer which has been modified with terminal unsaturated groups of the formula —C(R1)═CH2 wherein R1 is hydrogen, alkyl or aryl and wherein the AOC polymer is a hydrophobic polymer having an acid number between 5 to 30. The resulting aqueous hybrid polymer dispersion can be used for the manufacture of coating compositions, ink compositions or adhesives and coating compositions comprising the hybrid polymer dispersion as a binder.

A process for preparing an aqueous emulsion polymer including providing at least one ethylenically unsaturated monomer and a free radical redox initiator system under emulsion polymerization conditions, the redox initiator system including a water-soluble oxidizing agent, a water-insoluble oxidizing agent, and a sulfinic acid, or salts thereof, reducing agent; and effecting the polymerization of at least some of the ethylenically unsaturated monomer is provided. Also provided is a process for reducing the residual ethylenically unsaturated monomer content of an aqueous emulsion polymer.

The invention discloses a preparation method of polyurethane prepolymer with low free isocyanate monomer. The preparation method comprises the following steps of: forming into mixed alcohol by trihydric alcohol and dihydric alcohol under the temperature of 120-150DEG C, and carrying out vacuum dehydration; putting isocyanate monomer and ester solvents into a reactor to keep the temperature at 30-70DEG C, and dropwise adding the mixed alcohol into the reactor; after dropwise adding, continuously reacting for 3-6h under the temperature of 40-70DEG C under stirring, and discharging in a cooling way to obtain polyurethane prepolymer; and separating the obtained polyurethane prepolymer, and adjusting the solid content of polyurethane prepolymer solid and the content of free isocyanate monomer in the separated heavy components by diluted solvent. According to the preparation method, the real continuous production can be realized, all the recovered solvent and isocyanate monomer can be recycled, the zero emission can be realized, and the real clean production can be realized; and the product has the characteristics of being low in viscosity, high and adjustable in NCO value content, low in the content of the free isocyanate monomer, high in solid content, good in compatibility, etc.

The invention discloses a method for preparing a high-density polyethylene-maleic anhydride grafted copolymer adopting a suspension method. The polymer prepared by the method has high grafted rate, less solvent is used, the content of a cross-linking substance tends to zero, simple equipment and process are adopted, and the polymer is convenient to produce in a large scale. According to the grafting method for grafting maleic anhydride (MAH) to high-density polyethylene (HDPE), the grafting reaction is carried out in a high-pressure reactor by adopting a suspension polymerization method by adding the HDPE and swelling agent thereof, the MAH, an interface agent, a surfactant and water in the high-pressure reactor, stirring, increasing temperature to fuse the HDPE, and dropwise adding an initiating agent to carry out a suspension grafting reaction, wherein the initiating agent is dispersed in the swelling agent of the HDPE first.