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

The invention relates to a preparation method of instant ultra-high molecular weight polyacrylamide dry powder. The method comprises the following steps of: taking acrylic amide AM as a monomer, adopting a low-temperature composite initiation system taking NTP and K2S2O8 as main initiators, and an azo compound as an auxiliary initiator; adopting ammonia water and urea as cosolvents; and adding the initiator in batches and controlling the concentration of the cosolvent and the pH value of the medium, so as to obtain the instant ultra-high molecular weight polyacrylamide dry powder. The relative molecular weight range of the ultra-high molecular weight polyacrylamide PAM is that Mw is smaller than or equal to 25000000 and greater than or equal to 5000000. The optimal production technology is determined by discussing the influence factors such as the initiation system, the cosolvent concentration, and the pH value of the medium; the obtained polyacrylamide is rapidly dissolved, and is high in relative molecular weight, high in percent conversion, low in monomer content, high in production efficiency, low in cost and suitable for industrial production.

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 discloses a preparation method for a low-color number environment-friendly polyurethane curing agent. The method comprises the following steps of 1, continuously reacting dihydric alcohol, trimethylolpropane and toluene diisocynate to generate prepolymer reaction liquid by using a continuous reaction device, wherein the trimethylolpropane is fed in a batch addition way; 2, separating the prepolymer reaction liquid by using two stages of film evaporators, pumping evaporation residues obtained by separation into a diluting tank by using a pump, and performing diluting to obtain low-free isocyanate monomer content polyurethane curing agent. The method has the advantages that the whole production process is continuous, the use of a solvent is avoided, reaction heat is maximally utilized, the method is energy-saving and environmentally friendly, the color of a product is improved, and the quality of the curing agent product is improved.

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 provides a high-grating-rate and low-odor polypropylene resin composition and a preparation method thereof. The polypropylene resin composition consists of the following components in parts by weight: 100 parts of polypropylene resin, 1-3 parts of a polar monomer, 0.01-1 part of an initiator A, 0.01-1 part of an initiator B and 0.5-2 parts of a second monomer. The preparation method comprises the steps of weighing raw materials according to the weight part, mixing the raw materials in a high-speed mixer for 2-5min and discharging materials; and implementing reactive extrusion grafting on the mixed raw materials through a dual-screw extruder. The polypropylene resin composition disclosed by the invention, through selecting initiator and comonomer, reduces pungent odor of materials and improves grafting efficiency. The prepared polypropylene disclosed by the invention has the advantages of light product odor, high grating rate and low gel rate, and is applicable to a flexibilizer and a compatilizer of polar monomer and non-polar polymer alloy; the polypropylene resin composition is used for filling or strengthening polypropylene, and is capable of improving the mechanical performance and the heat resistance of the material.

The invention discloses a nonionic and anionic mixed waterborne polyurethane curing agent and a preparation method thereof. The method comprises the following steps of: adding oligomer polyols to an HDI monomer in the presence of nitrogen, stirring and heating the oligomer polyols and the HDI monomer to 60-80 DEG C, and carrying out heat preservation and reaction for 2-3 hours to obtain an additive product; adding a trimer catalyzer to the additive product, carrying out thermal reaction at 60-80 DEG C; when the NCO content reaches a target value, removing unreacted HDI monomer under the conditions of 150-180 DEG C and 0.01-0.05Torr to obtain an HDI prepolymer; cooling the obtained HDI prepolymer to 60-70 DEG C, adding an anion modifier and carrying out thermal reaction for 2-4 hours; and adding a neutralizer, reacting for 0.5-1 hour, cooling and discharging the product to obtain the waterborne polyurethane curing agent. The preparation method disclosed by the invention is simple; the obtained waterborne polyurethane curing agent is light in color, high in effective -NCO content, yellowing-resistant and good in storage stability.

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.

A functionalized copolymer containing a main chain derived from polymerizable monomers and pendent functional groups terminated with one or more α or β ethylenically or acetylenically unsaturated groups. The functionalized copolymers are self cross-linking and are suitable for use as binders.

The invention relates to a process for the manufacture of an auto-oxidatively cross-linking hybrid polymer, in particular an aqueous hybrid polymer dispersion, comprising the step of reacting in a mini-emulsion process one or more ethylenically unsaturated monomers to form an addition polymer (also referred to as a vinyl 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 can be hydrogen, alkyl or aryl and wherein the modified AOC polymer is a hydrophobic polymer having an acid number between 5 to 30. In particular, the invention relates to a process comprising mixing one or more modified AOC polymers, one or more ethylenically unsaturated monomers and one or more surfactants and forming a mini-emulsion in water and addition polymerizing the unsaturated monomers in the mini-emulsion to form a dispersion of hybrid particles of the modified auto-oxidatively crosslinkable polymer and the addition polymer. The invention further relates to the aqueous hybrid polymer dispersion obtainable by the process according to the invention, the use thereof for the manufacture of coating compositions, ink compositions or adhesives and to coating compositions comprising the hybrid polymer dispersion as a binder.

This method for removing the unreacted monomers from the vinylidene chloride resin slurry comprises keeping an aqueous medium in the vinylidene chloride resin slurry containing the unreacted monomers and obtained by polymerization in the aqueous medium in a boiling state at <=80 deg.C temperature under a reduced pressure and vaporizing the unreacted monomers. The method for recovering the unreacted monomers from the vinylidene chloride resin slurry comprises cooling the removed unreacted monomer component, separating water, then further cooling the unreacted monomer component, liquefying the gaseous unreacted monomers and recovering the unreacted monomers.

The invention discloses a resource utilization method by using biological power plant waste, and relates to the technical field of biological power plant waste utilization. The biological power plantwaste is processed into a soil improvement agent, wherein the soil improvement agent comprises the following components in parts by weight: 15-25 parts of animal manure, 10-15 parts of straw, 3-4 parts of zeolite, 5-6 parts of bentonite, and 2-3 parts of vermiculite, the pH value being adjusted to 6.0-6.5. The method has the following advantages: through mutual cooperation of the animal waste, theplant straw, the bentonite, the zeolite and the vermiculite system, the toxic action of heavy metals can be effectively inhibited, the effectiveness of trace elements in soil is improved, the nutritional environment of crop roots is improved, the soil structure and the water retention property are effectively improved, and the continuity of the soil improvement effect of the soil conditioner is guaranteed.

A composition for preparing an injection fluid in oil and gas recovery comprising an inverse emulsion of a water-soluble polymer A comprising cationic monomer units, and solid particles of a water-soluble polymer B comprising cationic monomer units, and wherein water-soluble polymer A comprises between 10 and 40 mol % of a cationic monomer units based on the total amount of monomer units; and wherein the cationicity in mol % of polymer A is superior or equal to the cationicity in mol % of polymer B. Method of treating a portion of subterranean formation comprising providing said composition, preparing an injection fluid with at least said composition, introducing the injection fluid into portion of the subterranean formation. The composition is particularly useful to prepare fracturing fluid in fracturing operations.