36results about How to "High-NCO content" patented technology

Compositions incorporating water-curable urethane constituent(s) are formulated with favorable viscosity and viscosity stability characteristics, while at the same time, preserving desired hardness characteristics. The present invention is particularly useful in applications in which water-curable compositions include NCO-functional resins having relatively high NCO content and / or incorporate MDI-based constituents. Preferred modes of practicing the invention include implementing one or more formulation strategies to help retain hardness while preserving good viscosity characteristics. These preferred strategies involve (i) balancing scavenger, polyisocyanate and polyfunctional polyol content of the compositions or resins thereof, as the case may be, (ii) formulating an NCO-functional resin with chain extender constituent(s) to enhance viscosity stability, (iii) formulating with one or more plasticizers that enhance viscosity performance, and (iv) combinations of two or more of these strategies.

The invention discloses a method for preparing a polyurethane-modified organosilicon double-component room-curing elastomer adhesive, which comprises the following steps: (1) uniformly mixing hydroxypropyl-terminated silicone oil and glycerol, and dehydrating to obtain a hydroxyl-terminated (-OH) component; (2) reacting aromatic polyisocyanate, the hydroxyl-terminated (-OH) component and dibutyltin dilaurate to obtain a component A; (3) adding vapor-phase silica white, carbon black and talcum powder into the container filled with hydroxy silicone oil and dihydroxy polysiloxane, adding a catalyst, adding 3-aminopropyl triethoxy silane, finally adding a defoaming agent, uniformly mixing, and drying to obtain a component B; and (4) uniformly mixing the component A and component B in a mass ratio of 12:(23.5-24), and curing at room temperature for 4-5 hours. The elastomer adhesive prepared by the method has the advantages of favorable tear resistance, excellent high / low temperature resistance and excellent binding property. The preparation method is easy to operate and accessible in raw materials, and lowers the preparation cost.

The preparation process of low free toluene diisocyanate as curing agent includes the following steps: reaction between toluene diisocyanate and polyol in the NCO / OH molar ratio 2-3 at 50-80 deg.c with reaction medium SO2, gamma-butrrolactone, dimethhyl sulfoxide, dimethyl carboxy diacid ester; adding polyisocyanate polymerizing catalyst when the content of NCO is 15-16 % for further reaction and adding polyisocyanate polymerizing inhibitor when the content of NCO is 14-15%; adding fatty hydrocarbon and / or cyclic fatty hydrocarbon as extracting agent for multiple extraction, eliminating the extracting agent through letting stand or distillation; and diluting and discharging pre-polymer. The present invention can prepare curing agent with low chroma, low visosity and high NCO content and no toluene diisocyanate monomer and other toxic matter.

The invention belongs to the technical field of chemistry and particularly discloses low-viscosity liquefaction modified MDI (4,4'-diphenylmethane diisocyanate) and a preparation method thereof. The liquefaction modified MDI has the viscosity of 310-380 mPa.s and the NCO content of 18%-21%. The method comprises the steps as follows: a) MDI is added to a reactor provided with temperature control, stirring and reflux condensation devices to be heated under the protection condition of inert gas, and the temperature is kept at 50-55 DEG C until MDI is molten into a liquid; b) the temperature is increased to 78-98 DEG C, a catalyst A and mono-hydroxyl small-molecular alcohol are added, the mixture reacts completely, then, the temperature is decreased to 60-75 DEG C, and macromolecular polyols are added; c) a stabilizer B is added, the experiment is ended after 0.5-2 h, and the temperature is decreased to the room temperature. The method is low in raw material cost, simple in process and easy to control in process condition when used for synthesizing the low-viscosity liquefaction modified MDI. The low-viscosity liquefaction modified MDI has high reaction activity and good storage stability and can be used for preparing room-temperature casting polyurethane elastomers, coatings, adhesives and sealants.