Recovery Technology of DMF from Wet Type Polyurethane Synthetic Leather Waste Gas

A new recovery technology is developed to recycle N,N-dimethyl formamide （DMF） in waste gas from wet type polyurethane synthetic leather industry. Given that the concentration of DMF in waste gas was as low as 325.6- 688.3 mg·m^-3, it was necessary to make sure two phases contact adequately and strengthen the mass transfer by increasing contact area and enhancing the turbulence. Therefore, two-stage countercurrent absorption and two-stage fog removing system were introduced into the technology. The top section of the absorption column was filled with structured wire-ripple stainless steel packing BX500, while the lower section with sting-ripple packing CB250Y. Total height of packing material was 6 m. In addition, there were both two-stage fog removing layer and high efficiency liquid distributor at the column top. All the operating parameters, including temperature, pressure, flow rate and liquid position, could be controlled by computers without manual operation, making sure the outlet gas achieved the national emission standard that the DMF concentration should be below 40 mg·m^-3. The whole equipment could recover 237.6 t of DMF each year, with the profit up to CNY 521×10^3.

Synthesis of Hyperbranched Polymers and Its Effect on Water Vapor Permeability of Microfiber Synthetic Leather

A series of hyperbranched poly(amine-ester)polyols were synthesized by the polycondensation of N,N-diethylol-3-amine-methylpropionate(prepared by Michael addition reaction of methyl acrylate with diethanolamine)as an AB2-type monomer with trimethylol propane as the core moiety,proceeding in one-step procedure in the melt with p-toluenesulfonic acid as catalyst.The obtained monomer and polymers were characterized by FTIR and 1H-NMR spectroscopy.The solubility and surface activity in aqueous solution of the polymers were also examined.The gas permeability,water vapor permeability,and moisture absorption of microfiber synthetic leather treated by hyperbranched polymer were studied.The optimum conditions were that the dosage of dye and hyperbranched polymer was 5% and 10%,respectively.The water vapor permeability and moisture absorption of microfiber synthetic leather reached to 0.525 4 mg/(10 cm2·24 h)and 0.046 7 mg/(10 cm2·24 h).Compared with blank samples,they increased by 15% and 35%,respectively.However,the dosage of hyperbranched polymer has little influence on gas permeability of microfiber synthetic leather.SEM results show that the fiber of microfiber synthetic leather treated by hyperbranched polymer is incompact.

Application of Cationic Waterborne Polyurethane as Impregnation Material for Microfiber Synthetic Leather Base

A cationic waterborne polyurethane(CWPU) was synthesized and utilized as impregnation material for manufacturing microfiber synthetic leather base,in an attempt to decrease environmental pollution associated with organic solvents and improve simulation degree relative to genuine leather.The alkali resistance of the CWPU and four manufacture methods were investigated.Meanwhile,the dyeing properties of the microfiber synthetic leather base were studied.It was found that the CWPU displayed enough alkali resistance to endure the alkali deweighting process for microfiber synthetic leather base manufacture.In terms of bending length,bending rigidity,compression elasticity ratio and specific compression elasticity ratio of the resulting base,coagulating the impregnated CWPU with sodium hydroxide before steam treatment was the optimal method.The extent of fiber splitting and the handle of the base from this method were both similar to conventional base filled with solvent-based polyurethane(SPU).The dyeing properties of the microfiber synthetic leather base filled with CWPU were also found superior to the one filled with either anionic waterborne polyurethane(AWPU) or SPU.

Wearable synthetic leather-based high-performance X-ray shielding materials enabled by the plant polyphenol-and hierarchical structure-facilitated dispersion

Effective protection against X-ray is the premise of utilizing the X-ray,thus it is critical to develop novel X-ray shielding materials with both low density and high X-ray attenuation efficiency.As the even distribution of high-Z element components is of great significance for increasing the attenuation efficiency of X-ray shielding materials,in this study,the microfiber membrane(MFM),a type of synthetic leather featuring hierarchical structure was chosen to provide large surface area for the dispersion of rare earth(RE)element.Meanwhile,plant polyphenol was utilized to achieve the stable loading and uniform dispersion of the Ce or Er into MFM.Benefiting from the assistance of polyphenol and hierarchical structure of MFM,the even dispersion of RE element was successfully realized.The resultant shielding materials displayed approximately 10%superior X-ray attenuation efficiency compared to that without polyphenol,and an averagely 9%increment in X-ray attenuation efficiency than that without hierarchical structure.Moreover,the obtained composite with a thickness of 2.8 mm displayed superior X-ray shielding performance compared to 0.25 mm lead sheet in 16-83 keV and retained an ultralow density of 1.4 g cm^(-3).Our research results would shed new light on the manufacture of high-performance X-ray shielding materials with excellent X-ray shielding performance.

Organosilicon leather coating technology based on carbon peak strategy

Based on the demand of carbon peak and carbon emission reduction strategy,divinyl-terminated polydimethyl-siloxane(^(Vi)PDMS^(Vi)),poly(methylhydrosiloxane)(PMHS),divinyl-terminated polymethylvinylsiloxane(ViPMVSVi),and fumed silica were used as primary raw materials,polydimethylsiloxane(PDMS)synthetic leather coating was in situ constructed by thermally induced hydrosilylation polymerization on the synthetic leather substrate.The effect of the viscosity of^(Vi)PDMS^(Vi),the active hydrogen content of PMHS,the molar ratio of vinyl groups to active hydrogen,the dosage of ViPMVSVi and fumed silica on the performance of PDMS polymer coating,including mechanical properties,cold resistance,flexural resistance,abrasion resistance,hydrophobic and anti-fouling properties were investigated.The results show that^(Vi)PDMS^(Vi)with high vinyl content and PMHS with low active hydrogen content is more conducive to obtaining organosilicon coating with better mechanical properties,the optimized dosage of ViPMVSVi and fumed silica was 7 wt%and 40 wt%,respectively.In this case,the tensile strength and the broken elongation of the PDMS polymer coating reached 5.96 MPa and 481%,showing reasonable mechanical properties for leather coating.Compared with polyurethane based or polyvinyl chloride based synthetic leather,the silicon based synthetic leather prepared by this method exhibits excellent cold resistance,abrasion resistance,super hydrophobicity,and anti-fouling characteristics.

Organosilicon leather coating technology based on carbon peak strategy

Based on the demand of carbon peak and carbon emission reduction strategy, divinyl-terminated polydimethyl-siloxane (ViPDMSVi), poly(methylhydrosiloxane) (PMHS), divinyl-terminated polymethylvinylsiloxane (ViPMVSVi), and fumed silica were used as primary raw materials, polydimethylsiloxane (PDMS) synthetic leather coating was in situ constructed by thermally induced hydrosilylation polymerization on the synthetic leather substrate. The effect of the viscosity of ViPDMSVi, the active hydrogen content of PMHS, the molar ratio of vinyl groups to active hydrogen, the dosage of ViPMVSVi and fumed silica on the performance of PDMS polymer coating, including mechanical properties, cold resistance, flexural resistance, abrasion resistance, hydrophobic and anti-fouling properties were investigated. The results show that ViPDMSVi with high vinyl content and PMHS with low active hydrogen content is more conducive to obtaining organosilicon coating with better mechanical properties, the optimized dosage of ViPMVSVi and fumed silica was 7 wt% and 40 wt%, respectively. In this case, the tensile strength and the broken elongation of the PDMS polymer coating reached 5.96 MPa and 481%, showing reasonable mechanical properties for leather coating. Compared with polyurethane based or polyvinyl chloride based synthetic leather, the silicon based synthetic leather prepared by this method exhibits excellent cold resistance, abrasion resistance, super hydrophobicity, and anti-fouling characteristics.

Preparation Technology of Solvent-free Polyurethane:A Mini-Review

Solvent-free polyurethanes are synthesized under certain conditions via a rapid reaction between liquid prepolymers.During this process the molecular weight of the polymer is rapidly increased to produce polymeric materials containing a carbamate-based structure at a very fast rate.The organic solvents are completely avoided in the solvent-free polyurethane synthesis process,thus avoiding all the problems associated with the use of organic solvents.Solvent-free polyurethane synthetic leather is extruded directly without adding solvents in the production and processing process,which has the advantages of low VOC emission and environmentally friendly.This review brings together theoretical and experimental research on the application and synthesis and preparation of solvent-free polyurethanes to generate an understanding of the theory and synthesis and preparation techniques associated with solvent-free polyurethanes.The review includes(i)the application and development direction of solvent-free polyurethane,(ii)an overview of the technology of solvent-free polyurethane synthetic leather preparation,(iii)a study of the modification and synthesis of solvent-free polyurethane prepolymers,(iv)a summary of the technology of rapid foam forming of solvent-free polyurethane and its influencing factors,(v)a review of the technology of solvent-free polyurethane synthetic leather preparation.In addition to the review,a corresponding overview of the theoretical and experimental advances in solvent-free delayed foaming technology in recent years and a summary of the technology and experience in the preparation of solvent-free polyurethanes are also presented.