| At present,ammonium stearate emulsion(ASE)is the foam stabilizer used in water-based polyurethane(WPU)mechanical foaming,but ASE has a large odor,and it is prone to reverse thickening and stratification in the placement process.At the same time,the WPU foaming coating prepared by ASE is easy to decompose,and it is easy to appear white in the black WPU foaming coating.To solve these problems,it is urgent to develop a green and efficient foaming stabilizer for WPU foaming coating.In this paper,hydrocarbon and fluorocarbon surfactant as raw material,formula design and optimization,preparation of a hydrocarbon surfactant as raw material,has excellent foaming stability of foam foam stabilizer(CH);And another fluorocarbon surfactant as raw material,with excellent foaming stability and foam leveling performance of fluorocarbon foam stabilizer(CF).Through the systematic study of foaming and stabilizing properties of various surfactants,the surface interface properties,liquid film strength and membrane structure of the compound system were studied to explore the foaming mechanism of the compound system.Finally,the new foam stabilizer developed not only has the function of smoothing and stabilizing foam,but also presents good environmental benefits.The specific research contents and conclusions are as follows:(1)The influence of anionic(K12,LAS,AOS),nonionic(6501,AEO-9,Span-60,APG0814,TX-10)and the combination systems of anion-nonion,anion-cation(CTAB)and anion-cation-nonion on foam stability of waterborne polyurethane emulsion was systematically studied.Taking foaming height and foam half-life as evaluation indexes,the foaming performance and foam stability performance were studied under different concentrations and different proportions.Further through the test of surface tension and liquid film strength,the surface interface properties and liquid film structure were analyzed to explore the mechanism of foam stability.By means of mechanical foaming and scraping drying,the WPU foaming coating prepared by high temperature was placed under a microscope to observe the pore structure and pore size distribution.Finally,a foaming stabilizer formulation with stronger foaming performance and better foaming stability was explored.The results showed that when anionic surfactants were used alone,the optimal concentration was 0.3 mmol/mL,and AOS had the best effect.When non-ionic surfactants are used alone,APG0814 has the strongest foaming performance at room temperature,Span-60 has the strongest foaming performance,Span-60 has the largest liquid film strength at room temperature,and APG0814 has the smallest average pore diameter.After mixing anionic surfactant,non-ionic surfactant and CTAB,it was found that the highest foaming height was 7.8 mL when the molar ratio of CTAB to LAS was 1/1.When the mole ratio of CTAB and K12 is 1/3,the foam stability is the best,the average pore diameter of the prepared WPU foam coating is the smallest,the average pore diameter is 62 ?m.In the anion-cation-nonioncompounding system,the stomatal diameter of WPU foaming coating prepared at high temperature was mainly studied,and the formula of CH was screened by liquid film strength test:The mole ratio of CTAB/K12/6501/AEO-9/APG0814 is 0.075/0.225/0.1/0.1/0.1,and the minimum pore diameter is 52 ?m.(2)The foam stability and absorption properties of three common fluorocarbon surfactants(FC-80,FC-134 and OBS)were systematically studied,and then the foam stability of the anion-cation combination system of fluorocarbon surfactants was studied.Finally,the effects of the combination of fluorocarbon surfactant and hydrocarbon surfactant used in chapter 2 on the foam properties of WPU emulsion system were studied.The foam height and foam half-life were taken as the main evaluation indexes,the surface interface properties and membrane structure of WPU system were analyzed,and the mechanism of foam stabilization and evenness was put forward.By means of mechanical foaming and scraping drying process,the average pore diameter and uniform pore degree of WPU foaming coating prepared at high temperature were studied.Finally,a foaming stabilizer formulation with good foaming stability and evenness was developed.It was found that when the concentration was 0.3 mmol/mL,FC-134 had the strongest foaming performance at room temperature,and the foaming height was 8 mL.The longest half-life of foam at room temperature is OBS,which is 434 min.The average pore diameter of the prepared WPU foam coating is the smallest,which OBS is 56 ?m.The highest stomatal average degree was FC-134,with a variance of 710.When cationic and anionic fluorocarbonic surfactants were mixed at a total concentration of 0.05 mmol/mL,when the mole ratio of FC-134 to OBS was 1/5,the foaming performance was the strongest,and the foaming height was 7.6 mL.Its foam half-life is the longest,the maximum is 464 min;When the molar ratio of FC-134 to OBS is 1/9,the average pore diameter of WPU foam coating is the smallest,the average pore diameter is 59 ?m,and the pore diameter is the best,and the variance is 484.In order to reduce the amount of fluorocarbon surfactants,fluorocarbon surfactants and hydrocarbon surfactants were mixed.The combination of fluorocarbon anionic surfactants and CTAB,fluorocarbon cations and hydrocarbon anions and fluorocarbon surfactants and hydrocarbon non-ionic surfactants were studied.The effect of compounding on the pore diameter of WPU foam coating was studied.The results show that the average pore diameter of WPU foam coating prepared by OBS and Span-60 is the smallest,the minimum is 60 ?m.The pores of WPU foaming coatings prepared by FC-80 and AEO-9 were the best,and the variance was 560.According to the above studies,it was found through TEM and liquid film strength study that the combination of FC-134 and OBS could form vesicles,thus improving the stability of liquid film.Thus,the formula of CF was determined as follows:the mole ratio of FC-134 to OBS was 1/9,that is,the concentration of FC-134 was 0.005 mmol/mL,and the concentration of OBS was 0.045 mmol/mL.(3)The two foaming stabilizers(CH and CF)developed were applied to WPU foaming coating and compared with ASE to explore the effects of different foaming agent dosage,drying temperature,pH value and composite calcium carbonate on the mechanical strength,porosity structure,moisture permeability and swelling rate of WPU foaming coating.The optimum process of WPU foaming coating was studied with the average diameter of pores as the evaluation index.The results showed that the optimum preparation conditions were as follows:10%addition,100? drying temperature,pH 9.2,15%calcium carbonate filler.The WPU foam coating prepared by the optimal process using CH and CF has better foam stability than ASE,smaller pore diameter,wider application range of pH,and better dispersion of calcium carbonate,among which the pores formed by CF are more uniform.The results showed that CH and CF were superior to ASE in tensile strength,elongation at break and moisture permeability of WPU foam coating.The addition of calcium carbonate filler can effectively improve the tensile strength,but also reduce the elongation at break and moisture permeability. |
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