The influence of chain extender for waterborne polyurethane

The influence of chain extender for waterborne polyurethane, the effect of waterproof coating is a kind of environmental protection is waterproof coating, because of its low temperature resistance, abrasion resistance by changing the type and ratio of raw materials can adjust its performance significantly. Chain extender contains rigid chain segments can be improved greatly WBPU latex film the characteristics of the mechanical properties and water resistance, make its application widespread attention.

Although waterborne polyurethane waterproof coating possesses numerous advantages of the above, but low in waterborne polyurethane water resistance has been a bottleneck of restricting its widespread use. So the research on its water resistance received extensive attention of many researchers.

Described in the literature by introducing more isocyanate polyurethane molecular chain (mainly three isocyanate) get to prepay pu water dispersion system, can greatly improve the water resistance of coating.

Studies have showed that BPA as chain extender, not only can improve the mechanical properties of resin, and can improve the glass transition temperature, the width of the internal friction peak broadening. Based on the above two ideas as well as researchers prophase work foundation, a mixture of DEG and DEG with BPA as chain extender, chain extender was studied in a single set of a very short moment ionic WBPU effect the performance of emulsion and latex film, in order to obtain suitable chain extender, made by a single set of a very short moment ionic WBPU waterproof coating has good water resistance and mechanical properties.

The synthesis of polymers. Add 500 g in 1000 ml flask three polyether glycol N - 220, decompression to - 0109 mpa, heated to a temperature of (120 + 5) ℃ for vacuum dehydration processing 3 h, then cooled to room temperature. Drops in proportion with TDI and the mixture of PAPI, add in the process of keeping temperature below 40 ℃, and about 40 min.

Add finished, oil bath heat, keep the reaction temperature at 75 + 5 ℃, reflux reaction 3 h. Reaction after cooling to room temperature, discharge, a quick pre polymers.

Extender chain reaction. To add a certain quality of pre polymers to three in the flask, and then add the dimer quality 50% acetone, stirring so that it is completely dissolved. Later, in the case of mixing to join a certain amount of chain extender, add after, to join the stannous caprylate, stirring for 10 min, heating up to 57 ℃ or so, reflux reaction of 5 h. Upon the reaction temperature to about 30 ℃, add a certain amount of TEA, and 5 min, finally, the speed of 3500 r/min under the high speed shearing dispersion, is calculated based on solid content need to join the deionized water, high speed dispersion 10 min, latex emulsion formation.

The preparation of latex film. Emulsion viscosity is small, solid content is 30%, the coating - about 4 cups of viscosity for 15 s. So, when the coating can be directly in the mold of their pp.47-53 membrane. In order to speed up its table dry and work time, three times coating, film thickness (1.5 + 0.2) mm. Maintenance requirements, in accordance with the GB/T16777-1997.




Chinese name: Diethyl toluene diamine(DETDA)

Chinese alias: aryl, aryl diethyl - aryl - methyl-p-phenylenediamine

English name: Benzenediamine, ar, ar-diethyl-ar-methyl-English aliases:Diethyltoluenediamine; ar, ar-Diethyl-ar-methylbenzenediamine;Diethylmethylbenzenediamine;

CAS No. :68479-98-1

EINECS No. :270 -877-4

Molecular formula: C11H18N2

Molecular Weight: 178.28

Boiling point: 310 ℃

Refractive index: 1.581

Flash Point: > 140 ℃

Inchi: InChI = 1/C11H18N2/c1-4-8-6-7 (3) 10 (12) 11 (13) 9 (8) 5-2/h6H ,4-5,12-13H2 ,1-3H3 density : 1.022

Risk Codes: R10; R35

RIDADR: UN 3082

Safety instructions: S2; S26; S39; S61

Packing Group: III

Hazard Class: 6.1


Bonding interface analysis. For the study of the PU film of PMMA on the surface of the adhesive effect, stripping interface with atomic force microscopy. Compared with pure PMMA board, it can be seen from the PU - EG with PMMA after stripping, the PM - MA side and PU - EG side more uneven, this shows that the PU - EG with PMMA interface stick relay is stronger. Calculated according to the height of the AFM imaging of the surface roughness of various materials and the section curve of each kind of material.

Pure PMMA surface calculated from a ~ c, PU - EG film stripping of PMMA surface and PU - 1, 4 - after the BG film stripping of PMMA on the surface of the root mean square roughness is 2.0 nm, respectively 21.6 nm and 17.0 nm, showed that after joining chain extender PMMA surface become rough, heralding the PMMA surface properties have changed. PU - EG - the roughness of the PMMA are slightly larger than the PU - 1, 4 - BG - PMMA, this may be related to the PU - EG peel strength of PMMA is bigger.

Only by AFM, test cannot determine whether left in PMMA on the surface of a thin layer of PU materials. Therefore, further the XPS analysis was carried out on the stripping interface.

XPS is the study of solid polymer surface composition and structure of one of the best technology. XPS technique was used to study the surface of pure PMMA, air - PU PU - EG interface surface, peel off the surface on one side of the interface between PMMA and stripping of PU - EG side surface chemical elements, four samples of XPS results show that there are C, O and N elements.

Four samples of C1s fitting spectrum, in 284.8 eV, respectively 286.4 eV and 288.9 eV in spectrum peak corresponds to the alkyl carbon (C - C and C - H), ether carbon (C - O) and carbonyl carbon (O C = O). Can see off on one side of the interface PMMA carbon functional group composition and pure PMMA extremely similar, showed no sticky PU - EG basic on the PMMA.

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