3844 results about "Polycondensation reaction" patented technology

A process for preparing a polymer having a 2,5-furandicarboxylate moiety within the polymer backbone and having a number average molecular weight of at least 10,000 (as determined by GPC based on polystyrene standards) includes a first step where a prepolymer is made having the 2,5-furandicarboxylate moiety within the polymer backbone, followed in a second step by a polycondensation reaction. In the first step a 2,5-furandicarboxylate ester is transesterified with a compound or mixture of compounds containing two or more hydroxyl groups, in the presence of a tin(IV) based transesterification catalyst. In the second step at reduced pressure and under melt conditions the prepolymer prepared in the first step is polycondensed in the presence of a tin (II) based polycondensation catalyst until the polymer is obtained. This polymer may then be subjected to Solid State Polycondensation. Polymers so produced may have a 2,5-furandicarboxylate moiety within the polymer backbone, and having a number average molecular weight of at least 20,000 (as determined by GPC based on styrene standards), and an absorbance as a 5 mg/mL solution in a dichloromethane:hexafluoroisopropanol 8:2 at 400 nm of below 0.05.

The present invention is a method for efficiently incorporating a UV absorber into a polyester resin. The method includes forming a reaction mixture comprising a diol component, a diacid component selected from the group consisting of dicarboxylic acids, dicarboxylic acid derivatives, and mixtures thereof, an antimony containing compound, a phosphorus containing compound, a metal containing compound, and a UV absorber. The reaction mixture is polymerized in a polycondensation reaction system. In another embodiment of the present invention, the UV absorber is added while the reaction products from one reactor are transferred to the next reactor in the polycondensation reaction system. A polyester composition having the UV absorber incorporated therein is also disclosed.

The invention discloses a preparation method of mesophase carbon microspheres from coal liquefaction residues serving as raw materials, which comprises the following steps of: firstly carrying out solvent extraction on the coal liquefaction residues, then carrying out a series of processing to obtain refined asphalt with different contents of quinoline insoluble substances, and carrying out thermal polycondensation reaction on the refined asphalt in the presence of a chemical auxiliary agent and a nucleating accelerator at the temperature of 380-450 DEG C, the pressure of 0-5 MPa and the stirring rotation speed of 40-500 r/min for 1-20 hours to obtain the mesophase microspheres. According to the invention, the chemical auxiliary agent and the nucleating accelerator can be added during theheat treatment process to improve the yield and narrow the particle size distribution of the mesophase carbon microbeads, and the mesophase carbon microspheres are prepared from the coal liquefactionresidues serving as the raw materials and have the advantages of low cost, simple preparation process, high yield (up to 35%), narrow particle size distribution, good sphericity, etc.

The invention discloses a preparation method for organosilicon, in particular relates to a preparation method of methyl-phenyl-vinyl silicone resin with high refractive index and high light transmission rate for packaging LED. The preparation method adopts the steps that the mixture of chlorosilane and toluene is added into the solvent which is composed of water and the toluene, the hydrolysis reaction is performed, then an amount of catalyzer is added into the silanol-toluene solution as hysrolysis product, the polycondensation reaction is performed, end capping reagent is finally added to perform the reaction, thus the objective product is obtained. The methyl-phenyl-vinyl silicone resin prepared by utilizing the method has the advantages of high refractive index, transparent clarification, radiation resistance, and high and low temperature resistance and weather resistance, thereby being especially suitable for the high modular basic glue in the packaging material for LED and expected to be applied in organosilicon material such as elastomeric sealant, pouring sealant, elastomoric adhesive and the like.

The invention discloses a method for preparing silicon dioxide aerogel with low density and large specific surface area at ordinary pressure. The method comprises the steps of taking cheap industrial water glass as a precursor and absolute ethyl alcohol as a solvent, performing hydrolysis and polycondensation reaction by the catalysis of acid and alkali respectively to form wet gel, performing water bath drying and aging, performing solvent exchange for many times, and performing graded drying at the ordinary pressure after surface modification to form the silicon dioxide aerogel with the low density. According to the method, the completely modified super hydrophobic silicon dioxide aerogel is obtained by using the least amount of modifier; the cheap industrial water glass is adopted as a silicon source, so that the production cost is greatly lowered; and the energy source is greatly saved for drying at the ordinary pressure in comparison with supercritical drying.

The invention discloses a graphene oxide/unsaturated polyester composite material and a preparation method of the composite material. The composite material comprises the raw materials: dihydric alcohol, graphene oxide, saturated binary acid or acid anhydride, unsaturated binary acid or acid anhydride, vinyl monomer, and normal polymerization inhibitor, initiator and accelerant, wherein the content of the graphene oxide is 0.06-0.5wt%. The preparation method of the graphene oxide/unsaturated polyester composite material comprises the following steps of: adding the graphene oxide into the dihydric alcohol to directly and ultrasonically disperse, or adding the dihydric alcohol into graphene oxide water solution to ultrasonically disperse and remove water in a fractional distillation way so as to obtain graphene oxide/dihydric alcohol solution which is evenly dispersed; performing polycondensation between the obtained graphene oxide/dihydric alcohol solution and the saturated binary acidor acid anhydride, unsaturated binary acid or acid anhydride and polymerization inhibitor with metering ratio, and diluting by adding the vinyl monomer after the polymerization so as to prepare graphene oxide/unsaturated polyester resin; and adding the initiator and the accelerant, and curing and crosslinking to prepare the graphene oxide/unsaturated polyester composite material.

The present invention is based upon the discovery that nontitanyl oxalates can enhance the catalytic functionality of titanyl oxalate catalysts. This invention provides a novel catalytic composition containing a titanyl oxalate catalyst and a metallic oxalate catalyst enhancer and optionally containing a metallic cocatalyst such as an antimony based catalyst. A synergistic relationship has been discovered between titanyl oxalate catalyst and the catalyst enhancer. A synergistic relationship has also been discovered between the titanyl oxalate catalyst, catalyst enhancer and a metallic cocatalyst such as antimony oxide or antimony triacetate. Also provided is an improved process of producing polyester by the polycondensation of polyester forming reactants in the presence of a catalytically effective amount of a polycondensation catalyst, wherein the improvement comprises utilizing, as the polycondensation catalyst, the novel catalyst composition containing a titanyl oxalate such as lithium titanyl oxalate and a catalyst enhancer such as a nontitanyl metallic oxalate like lithium oxalate and optionally containing a metallic catalyst such as antimony oxide or antimony triacetate. The improved process produces an improved polyester having lower acetaldehyde numbers and good color. The titanyl oxalate/catalyst enhancer composition can be used as a polycondensation catalyst in combination with other catalysts to achieve synergistic catalytic activity. Preferred is a combination of lithium or potassium titanyl oxalate, Li2 or K2TiO(C2O4)2, lithium or potassium oxalate, Li2 or K2(C2O4)2 with antimony oxide or antimony triacetate or antimony trisglycoxide.

The invention discloses a method for preparing polyester-polyester blocked copolyester, which comprises the following steps: (1) synthesizing an aromatic polyester hard segment to obtain a prepolymer P1 with a number-average molecular weight in the range of 500-10,000g/mol; (2) synthesizing an aliphatic polyester soft segment to obtain a prepolymer P2, wherein the prepolymer P2 can also be obtained by ring-opening polymerization of caprolactone monomer, and the number-average molecular weight of the prepolymer P2 is in the range of 500-10,000g/mol; (3) carrying out polycondensation reaction of the aromatic polyester oligomer and the aliphatic polyester oligomer: mixing the esterified product P1 and the esterified product P2, adding antioxidant, catalyst, passsivator and chain expander, allowing reaction at 220-260 DEG C to obtain a polyester-polyester block polyester elastomer. The catalysts used in the steps (1) and (2) are selected from titanium-containing organic substances. The method disclosed by the invention has the following advantages: (1) because the aliphatic polyester soft segment is introduced, the product has both the mechanical properties of the rigid aromatic polyester hard segment and the flexibility of the soft segment; and (2) because a number of assistants are added, the good chain expansion effect is achieved, and the reaction conditions are controlled.

The invention relates to low melting point copolyester and a preparation method thereof. The low melting point copolyester is made from the following monomers followed by the esterification reaction and the polycondensation reaction: (a) terephthalic acid (PTA) and isophthalic acid (IPA), (b) 1, 4- butanediol (BDO) and (c) polyethylene glycol 600 to 6000 (PEG); wherein, in the a component, the feeding mass ratio of the terephthalic acid and the isophthalic acid is between 80 to 20 : 20 to 80; in the c component, the feeding weight ratio of polyethylene glycol is 1 to 30 percent based on the a; the molar ratio of the a and the b is 1:1.5 to 2.3. The preparation method comprises an esterifcation stage and a polycondensation stage. The copolyester has the characteristics of low melting point, good crystallization property, high intrinsic viscosity and difficult adhesion of particles, and is suitable for spinning the filament, the staple fibers and the non-woven fabrics.

The invention belongs to the technical field of treatment and application of nanometer materials and industrial and agricultural wastewater, and provides a magnetic Fe3O4/SiO2/TiO2/quantum dot compounded nanometer photocatalyst and a preparation method and application thereof. The preparation method comprises the following steps of: synthesizing an Fe3O4 magnetic nucleus by a coprecipitation method; preparing an SiO2 protective layer by virtue of hydrolysis reaction and polycondensation reaction of TEOS (Tetraethyl Orthosilicate); then preparing a TiO2 layer on the surface of the SiO2 protective layer by a sol-gel method; and finally modifying Fe3O4/SiO2/TiO2 nanoparticles by CdS and CdSe quantum dots. The obtained magnetic Fe3O4/SiO2/TiO2/quantum dot compounded nanometer photocatalyst has very good visible-light photocatalytic capability, can be conveniently and fast recovered and reused by an external magnetic field, and can be used for removing organic pollutants of azo dyes contained in the industrial wastewater.

A binary titanium (VI) alkoxide compound is disclosed, which can be used as high-activity catalyst in esterification, ester exchange and polycondensation reactions. Said compound is prepared from easily hydrolytic Ti (VI) compounds or their hydrolyzed products and diol or hydrous diol through direct reaction to generate gel, regulating temp and pressure of reaction system or introducing inert gasto gradually remove the low-molecular resultants in reaction system, decolouring and drying. Its advantages include simple preparing process, low cost, and the high catalytic activity, optical catalytic performance and anti-hydrolysis nature of said product.

The invention discloses a colorless and transparent polyimide resin material. 1,2,3,4-cyclohexanetetracarboxylic dianhydride is chosen as dianhydride monomer or comonomer to carry out polycondensation reaction with primary diamine, so that the polyimide resin material is prepared. Because the 1,2,3,4-cyclohexanetetracarboxylic dianhydride comonomer has a distorted molecular structure, a large free volume exists between polymer molecular chains, and thereby the formation of charge transfer complex (CTC) in and between polyimide molecules is inhibited; and meanwhile, because of the introductionof a lipid structure, the electron-stimulated transition mode in the polyimide molecular chains is changed, the absorption of the aromatic polyimide in the visible light region is remarkably weakened, and thereby the transparency of the polymer is greatly increased. The ultraviolet light transmission cutoff wavelength of a produced polyimide film is 280nm to 380nm, the light transmissivity at 450nm is 86 to 94 percent, moreover, the glass-transition temperature is 250 DEG C to 400 DEG C, and the polyimide resin material has a good application prospect in the fields of flexible substrate materials for solar cells, flexible transparent conducting film substrate materials, liquid crystal display materials and the like.

The invention provides high molecular weight, crystalline or semi crystalline biodegradable and biocompatible poly(ester urea) (PEU) polymers useful for making vascular stents and hard tissue replacement implants, such as bone substitutes. The PEU polymers are based on α amino acids and are made by a polycondensation reaction. PEU polymer compositions can contain a therapeutic diol incorporated into the polymer backbone that is released from such an implant in situ. Bioactive agents, such as analgesics, antibiotics, and the like, can also be covalently attached to certain PEU polymers for release into tissue surrounding an implant during biodegradation of the polymer.

The invention relates to a method for preparing a modified copolyester composite fiber, in particular to a method for preparing a low-melting-point polyester composite fiber by adopting continuous polymerization and melt direct-spinning. The method comprises the following steps: slurry is prepared from raw materials in proportion and added continuously into an esterification system for an esterification reaction, an obtained oligomer is uniformly mixed with polyether, the mixture enters a homogenizing kettle for transesterification and pre-polycondensation, a product is uniformly mixed with a chain extender for final polycondensation, and an obtained low-melting-point polyester melt and a common polyester melt enter a composite spinning assembly to prepare the low-melting-point polyester composite fiber which comprises a common polyester core layer and a low-melting-point polyester cortex layer. The method has the advantages as follows: a side reaction of thermal degradation of polyether components is inhibited effectively, and the color and spinnability of the low-melting-point polyester melt are improved; the problem of poor performance of composite spinning of the low-melting-point polyester on the cortex layer and the common polyester on the core layer due to large dynamic viscosity difference of the melt is solved, and the composite fiber is well formed; the production efficiency of the low-melting-point polyester composite fiber is improved.

A high-activity catalyst for both esterification and polycondensation contains anti-hydrolytic high-activity glycol titanium, the acetate, carbonate or oxalate of (1-4)-valence metal ions, and at least one of alkoxyl compound, organic acid and phosphorous compound. Its advantages are high activity, short reaction period, and no environmental pollution. Its resultant polyester has high photochemical performance and whiteness.

The invention provides a formaldehyde catching agent. An efficient macromolecular type formaldehyde catching agent is synthesized by performing addition polycondensation reaction on a methyl acrylate monomer and a polyamine compound to generate an amino-group-enriched hyperbranched polymer and adding corresponding auxiliaries. According to the catching agent, formaldehyde is caught by using an amino group of the hyperbranched polymer and film forming fixing is implemented by using a carbon framework of an acrylate type substance; modification is realized by the corresponding various auxiliaries, so that the physical performance and the formaldehyde elimination effect are improved. The formaldehyde catching agent has the characteristics of no toxicity, no volatility and no irritating odor, and secondary harm to a human body is avoided; the formaldehyde catching agent can be limitlessly dissolved in water, is mild in property, free from corrosion, easy to add and spray, high in film forming property and durable.

The invention provides a SiO2 nanoscale porous material with aerogel property prepared by microwave reaction and a preparation method thereof; the nanoscale porous material comprises silicon dioxide skeletons (1) and bubble-shaped nanoscale pores (2), wherein the foam-shaped nanoscale pores (2) are arranged among the silicon dioxide skeletons (1). The preparation method comprises four steps, namely preparation of silicon dioxide sol, preparation of wet gel, aging of mother solution and drying at normal pressure and the preparation of silicon dioxide sol comprises the following steps: adopting organosiloxane, organic solvent, water and acid catalysis as raw materials; mixing each components in a defined ratio in a container while adopting microwave radiation to perform hydrolytic polycondensation reaction or adopting microwave radiation to perform hydrolytic polycondensation reaction after mixing the components. Owning to adopting microwave radiation technology, a lot of bubbles are generated in silicon dioxide sol, a large quantity of nanoscale bubble-shaped pores are formed on the silicon dioxide substrate, and meanwhile silicon dioxide space skeletons are retained so that silicon dioxide porous material with extremely large specific area and higher intensity can be obtained. In addition, because carbon dioxide supercritical drying process is not needed, the production cost is greatly reduced.

The invention discloses a microcellular polyurethane elastomer and a preparation method thereof. The elastomer contains two components, i.e., a polyol component and a prepolymer component, wherein the polyol component comprises polyester polyol, a chain extender, a foam stabilizer, water, a catalyst and the like; and the prepolymer component comprises polyester polyol, isocyanate and the like. The polyester polyol in the polyol component is prepared from a mixture of aromatic dibasic acid and aliphatic diacid and a mixture of diethylene glycol and other dihydric alcohols by means of polycondensation reaction. Compared with common microcellular polyester-type elastomers, the prepared elastomer has higher hardness and mechanical properties as well as better abrasive and bending resistances, besides, the flowability of materials is good. The material can be used in the fields like soles, solid tires, buffer blocks and the like. The preparation method is simple and feasible.

The invention relates to a preparation method of a silicone resin type organic/inorganic hybrid material for packaging. The invention aims to overcome the defects in the prior art, and provides a preparation method of a high-refractive-index high-light-transmittance silicone resin type organic/inorganic hybrid material for packaging. The method comprises the following steps: 1) cohydrolysis reaction; 2) prepolymer polycondensation reaction; and 3) packaging material preparation and vulcanization.

The invention discloses a thermo-sensitive chain extender and polyurethane hydrogel with double sensitivity of temperature and pH. The hydrogel is prepared by the following methods: mixing 15-20.6 percent of polyethylene glycol, 6.7-9.2 percent of polyhydric carboxylic acid, 25.2-34.6 percent of multi-isocyanate and dibutyltin dilaurate used as a catalyst to perform pre-condensation polymerization reaction; adding organic solvent to stop reaction to obtain a pre-polymer; adding 15.3-36.5 percent of a thermo-sensitive chain extender to perform chain extension reaction; adding 3.1-4.3 percent of polyhydric alcohol amine stop end after the pre-polymer is subjected to the chain extension; and then, adding 11.6-19.4 percent of a curing crosslinking agent to perform crosslinking reaction to obtain polyurethane hydrogel with double sensitivity of temperature and pH. The thermo-sensitive chain extender is prepared by the method, and a method for introducing the thermo-sensitive chain extenderin polyurethane is provided, and the softness and hardness of the material are controlled in a post-crosslinking mode, so that the defects that introduction of groups and cross-linking solidity are carried out at the same time in the conventional way of excitation of double bonds are overcame, and the polyurethane hydrogel with double sensitivity of temperature and pH is prepared.