78results about How to "Shorten the polymerization reaction time" patented technology

The invention discloses a preparation method of porous-super-absorbent resin. The preparation method comprises the following steps of: adding acyclic acid to deionized water, neutralizing with a sodium hydroxide aqueous solution, and controlling neutralization temperature at 50 DEG C to 80 DEG C and neutralization degree at 60-80%; mixing the solution; adding a cross-linking agent and stirring till completely dissolving, then adding an oxidant and a foaming agent, afterwards, adding a reducing agent, carrying out polymerization reaction by heat of neutralization, and generating porous-super-absorbent resin gel; and pelleting, drying, crushing and screening to obtain the porous-super-absorbent resin. Additional heating equipment is not needed in the porous-super-absorbent resin preparation method; heat released in neutralization process is directly used for enabling a polymerization reaction system to reach the temperature needed by the reaction; and an oxidation reduction initiating agent is added at high temperature, so that the whole polymerization reaction time is shortened, and the production efficiency is improved; and the added foaming agent can be used for preparing porous gel, so that the water retaining capacity and the water-absorption capability of the water-absorbent resin are improved.

The invention relates to a preparation method of super absorbent resin with high return permeability resistance. The method comprises the following steps: neutralizing an acrylic acid aqueous solution by using alkali, adding a composite initiator, a crosslinking agent and a foaming agent, and performing polymerization reaction under UV light irradiation; cutting up and pelleting hydrogel after polymerization, adding a gel cutting aid in the cut-up process, drying and pulverizing to obtain primary granules of super absorbent resin; and spray-coating the surfaces of the primary granules with surface crosslinking liquid, and performing reaction at high temperature to obtain a final product of the super absorbent resin. The super absorbent resin prepared by the method has the characteristics of high absorbing rate, high absorbing speed, high water-retaining property, excellent return permeability resistance and the like.

The present invention relates to a new process of synthesizing conductive polymers from monomers substituted with amine group. The process provides simple synthesizing steps for the conductive polymers without using other additives such as stabilizers or emulsifiers. The conductive polymers synthesized according to the present invention have highly enhanced solubility in common organic solvents and electrical conductivity compared to conventional conductive polymers. Therefore, the conductive polymers synthesized according to the present process can be utilized in applications that require high electrical conductivity, for example an electromagnetic interference shield or a transparent electrode of thin film, as well as in specific applications such as various conductive films, fibers, polymer blends, battery electrodes or conductive etch mask layers.

The invention discloses a preparation method for acrylonitrile/methacrylic acid copolymer foamed plastic. The preparation method comprises the following steps: adding deionized water, a suspending agent and an aqueous phase inhibitor into a reactor, and uniformly agitating; uniformly mixing monosomic acrylonitrile, methacrylic acid and an initiator, adding the mixture into the reactor, agitating the mixture at the room temperature so as to obtain a stable suspension, rising the temperature to a reaction temperature, and performing free radical suspension polymerization under the condition of agitation; drying a slurry-shaped mixture obtained after the reaction; uniformly mixing copolymer powder, a carbamide foaming agent and a bismaleimide (BMI) crosslinking agent which are obtained after drying; performing hot-pressing foaming formation of the mixture, and otaining polymethacrylimide foamed plastic via heat treatment. The technical scheme provided by the invention is high in production efficiency and yield, can obtain a product with stable performance, is simple and convenient to operate and environmental-friendly, and realizes a beneficial implement effect.

The invention discloses a titanium-silicon catalyst and a preparation method as well as an application thereof. The preparation method includes the following steps: (1) organic titanic acid ester and 2/3 cubic content of anhydrous alcohol are mixed evenly, and stirred sufficiently to achieve A solution; deionized water is mixed with the remained 1/3 cubic content of anhydrous alcohol sufficiently, acid or alkali is added, the acid or alkali concentration is controlled within 0.01-1mol/L, B solution is prepared, and B solution is dripped into A solution by a burette; (2) the mixture is stirred for 3-5 hours after dripping, the precipitate achieved after centrifugal separation is grinded and calcined to achieve titanium-silicon catalyst. The titanium-silicon catalyst achieved by the method is stable during the process of polymerization without hydrolysis reaction; the method can be used to catalytic synthesis of aliphatic and aromatic co-polyester, the titanium-silicon catalyst can reduce the dosage of catalyst, shorten the duration of polymerization, improve the quality of biodegradation co-polyester product, and the terminal carboxyl group content in the product as well as the b value are reduced.

The invention discloses a method for synthesizing polybutylene terephthalate. The method comprises steps of firstly carrying out esterification between diacid and dihydric alcohol in presence of a chelate titanium catalyst at 150-230 DEG C under normal pressure, when the reaction liquid is totally transparent, gradually raising temperature of a reaction system to be 240-265 DEG C and reducing pressure to be absolute pressure of 30-300Pa, and then carrying out polycondensation so as to prepare PBT (polybutylene terephthalate) with intrinsic viscosity of 0.75-1.1, wherein the chelate titanium catalyst is prepared from organic titanate and fatty dihydric alcohol through decompression reaction at 50-90 DEG C. According to PBT prepared by the method, on the basis of not lowering general performances, the chelate titanium catalyst has stronger catalytic activity compared with traditional a titanate catalyst.

The invention relates to a new process for SG3 type PVC (polyvinyl chloride) resin production, which comprises the following steps of: adding a vinyl chloride monomer, pure water, a dispersant, an initiator and a conventional amount of thermal stabilizer and terminator into a reaction kettle, and meanwhile adding a chain extender of maleic acid di-allyl ester into the reaction kettle; wherein the reaction kettle is in a middle size, the mass proportion of the monomer, the pure water, the dispersant, the initiator and the chain extender is 20,000-25,000:30,000-33,000:490-530:120-140:4.5-5.5, and the temperature of polymerization reaction is 54-58 DEG C. Under the condition of no changing of traditional main production equipment, the invention adjusts the proportioning of relevant auxiliary agents, improves the temperature of the polymerization reaction, optimizes the control conditions of the production, and shortens the time of the polymerization reaction for about 60 minutes while adding a proper amount of the chain extender in a production formula, thereby saving power and energy consumption, improving production capacity of the equipment, and having safe and stable production system operation and better economic benefit.

Provided is a preparation method for a polycarboxylate high-performance water reducer. The water reducer is prepared by copolymerization reaction of macromolecule monomer methoxy polyethylene glycol mono(meth) acrylate ester, small molecule monomer (meth)acrylic acid and sodium styrene sulfonate in an aqueous solution under the protection of inert gas and the action of a redox initiation system and a chain transferring agent. According to the invention, a high-activity redox initiation system is employed, which enhances the polymerization rate, reduces polymerization temperature, shortens reaction time, ensures non-hydrolysis of macro-molecular polyester monomers in the process of polymerization and a high conversion rate of raw materials, and guarantees that polymers have long side chains arraying at uniform intervals and an ideal comb shaped molecular structure. The water reducer prepared in the invention has the characteristics of a high water-reducing rate, a small slump loss and the like, and enables concrete with the water reducer to have high strength; simultaneously, the copolymerization reaction is carried out in water in the method, and therefore the method has the characteristics of simple preparation technology, environmental protection, low cost, etc.

This invention discloses a method to prepare polyvinyl fluoride in which vinyl fluoride is adopted as monomers for polymerization. It has the characteristics that polymerization takes place with the existence of soluble radical initiators and auxiliary reagents. The auxiliary reagents in this invention can be: A) neutral inorganic salts; B) alkali or alkali compounds; C) acid or acidic compounds. This invention has the advantages that compared to previous literature, a) polymerization time can be reduced and efficiency of catalyst and facility can be promoted without obvious change in product properties such as intrinsic viscosity, melting point and melting heat by addition of auxiliary reagent A); b) melting point and melting heat of the product can be raised by addition of auxiliary reagent B); c) melting point and melting heat of the product can be lowered by addition of auxiliary reagent C). The polyvinyl fluoride membrane by melting tape-casting extrusion with potential solvent such as N, N-dimethylformamide and biaxial orientation of vinyl fluoride has wonderful comprehensive properties.

The invention provides a solution polymerization method. The solution polymerization method comprises the following steps that an aqueous solution containing monomers and sodium hydrosulfite contact under oxidation reaction conditions; and after contact, the mixture is mixed with a persulfate under the conditions of acrylamide low-temperature polymerization, wherein the monomers comprise 75 to 100 mol% of acrylamide and a mole ratio of oxygen dissolved in the aqueous solution to sodium hydrosulfite is 1: (0.4 to 2). The solution polymerization method can avoid a process of nitrogen-filling oxygen-removal of an aqueous solution containing monomers, eliminate an inhibition effect produced by oxygen dissolved in the aqueous solution on monomer polymerization, realize preparation of an acrylamide polymer having ultra-high molecular weight, and greatly reduce polymerization time of acrylamide polymer preparation.

The invention relates to a preparation method of a narrow-distribution polyacrylonitrile-based carbon fiber spinning solution. The preparation method of the narrow-distribution polyacrylonitrile-basedcarbon fiber spinning solution mainly solves the problems of wide molecular weight distribution of polyacrylonitrile, high residual monomer content and long polymerization reaction time in the priorart. The preparation method of the narrow-distribution polyacrylonitrile-based carbon fiber spinning solution includes the following steps that (1) polymerization raw material acrylonitrile, a comonomer 1 and/or a comonomer 2, a solvent and an initiator are added into a reactor, a thermostatic reaction is started under the protection of inert gas to the reaction materials, and a reaction temperature is controlled to 60-65 DEG C; (2) when the conversion rate exceeds T1, the temperature is increased by 5-10 DEG C; (3) when the conversion rate exceeds T2, the temperature is increased by 5-10 DEGC; and (4) when the conversion rate reaches T3, the reaction is finished, and preparation of the spinning solution is completed. According to the technical scheme, the problems of wide molecular weight distribution of polyacrylonitrile, high residual monomer content and long polymerization reaction time are well solved, and the preparation method can be used in the industrial production of the polyacrylonitrile-based carbon fiber spinning solution.

The invention relates to a rapid emulsion polymerization method for vinyl acetate. The method comprises the followings steps of: adding 10-15 parts by mass of 16.7 percent polyvinyl alcohol, 17-88 parts by mass of an aqueous solution, 37-52 parts by mass of deionized water, 0.5-2 parts by mass of octyl phenol polyoxyethylene ether and 15-40 parts by mass of vinyl acetate into a reaction kettle with a thermometer and a stirring and reflowing device; stirring and mixing uniformly, and gradually heating to 45-70 DEG C; adding a persulfate aqueous solution and a silver ammonia solution respectively; reacting at the temperature of 45-70 DEG C for 20-45 minutes; and naturally cooling to the room temperature after finishing the reaction to obtain a milky white blueing light-stable vinyl acetate emulsion. The method has the beneficial effects: operation is easy, equipment is simple, polymerization temperature control conditions are reduced, the lowest reaction temperature can be lowered to 45 DEG C, and the polymerization reaction time can be shortened to 20-45 minutes.

The invention provides a preparation method for preparing type 26 fluororubber from a fluoroether sulfonate and belongs to the technical field of synthesis of the high polymer material fluoroelastomers. The preparation method comprises the following steps: 1) blowing nitrogen into an airtight polymerization reaction kettle to remove oxygen, and adding deionized water, an emulsifier, disodium hydrogen phosphate, potassium persulfate, diethyl malonate, vinylidene fluoride and hexafluoropropylene, wherein the emulsifier is the fluoroether sulfonate; 2) reacting under the pressure of 3.0-7.0Mpa and at a temperature ranging from 50 to 120 DEG C, starting a mixing propeller at a rotating speed of 300-700r/min, and ending the reaction after 0.5-2.5 hours, thereby obtaining fluororubber latex; 3) coagulating by use of calcium chloride, washing the coagulated solid particles by use of deionized water until the bubble disappears, and drying in vacuum to obtain the finished product. The preparation method for preparing the type 26 fluororubber from the fluoroether sulfonate has the advantages of increasing the molecular weight of the fluororubber, improving the molecular weight distribution and the mechanical properties of the fluororubber, and protecting the environment.

The invention relates to the field of fluorine-containing high molecular materials, in particular to an ethylene-tetrafluoroethylene copolymer and a preparation method thereof. The preparation method includes: (1), vacuumizing a high-pressure kettle, and adding a polymerization medium; (2), adding an initial monomer into the polymerization medium until pressure is 0.9-1.2 Mpa, heating to 58-62 DEG C, adding an initiator; (3), after reaction is started, continuously adding a replenishing monomer for equal-temperature equal-pressure polymerization, and stopping adding the replenishing monomer when adding amount of the replenishing monomer accounts for 10-14% of total mass of the polymerization medium and the replenishing monomer; (4), lowering temperature and pressure, discharging, washing materials, and drying to obtain the copolymer. The preparation method is short in polymerization time, simple to operate and easy for industrial production. The invention further provides application of the ethylene-tetrafluoroethylene copolymer in fuel hose inner layers.