Synthesis And Characterization Of High Solid Content Waterborne Polyurethane Containing Carboxylic And Sulfonic Groups

High-solid-content and high stability polyurethane dispersions(PUDs) have broad prospects in application of various fields including adhesive、leather、coating and so on. The usage of leather, textile、plastic film、paper and other soft base material demands the film which made by PUD to have excellent performance, such as high pliability, high water resistance, high acid and alkali resistance and pH with a wide scope of application. At present, DMPA is widely used in making PUDs in China, the oneness of raw material hinders the development of high-performance polyurethane dispersions to some extent. The hydrophilic group of PUD which synthesized by DMPA would stay in the hard part of PUDs, the large microphase separation between the soft and hard part will influence the performance of the films.Common Carboxylic acid type of water-based polyurethane has certain defects in each aspect, for example the following:first, low solid content(generally around30%),low film-forming rate and high cost. Second, poor water resistance. The existence of hydrophilic groups in the molecular chain has negative influence on water resistance. Third, poor performance on weather resistance、solvent resistance、 initial viscosity. In addition, low hardness and low strength.In order to improve the performance of waterborne polyurethane, modification is often made and new raw materials are often used. Related research shows that Sulfonic acid type of water-based polyurethane can improve the solid content and stability of polyurethane dispersions and make the emulsion have a wider pH range, at the same time, it can improve the started bonding strength、hydrolysis-resistant as well as tensile strength of polyurethane films. By adopting new type of polyester polyol containing sulfonate (S3001) as raw material, bringing sulfonate groups into common carboxylic acid water-based polyurethane as soft segment, solid content of waterborne polyurethane can be improved, at the same time, because of the higher crystallization property of S3001, it can increase the physical properties\hydrolsis resistant and thermal stability of Waterborne polyurethane films,and modifies the pH range(the tolerance when blending with ethylene-vinyl acetate copolymer(VAE)).The experiment parts of this paper chose S3001as new raw material and did the research mainly in the following two aspects:(1)This paper adopted the acetone method, took new type of polyester polyol containing sulfonate (S3001) and DMPA as hydrophilic monomer, used IPDI, polyether polyol (N220,Mn=2000), PBA(Mn=2000) and DEG as raw materials, and made polyurethane dispersions successfully which had high solid content(more than40%), low viscosity, stable condition, at the same time, used less solvent.(2)Because of the high viscosity of the raw material and the high reaction activity, the products need to have greater hardness. polyurethane will be small in emulsion particle diameter, fine in the appearance and need less solvent if it’s prepared in the way of the chain extender and it would be better to add prepolymer to emulsify it after dissolving EDA in water, especially controlling the quantity of EDA at the state of2.1%. The infrared test proved that waterborne polyurethane with carboxylic acid and sulfonic acid groups is successfully synthesized.(3)The content of DMPA was changed from3.1%to6.24%,the Particle size test and Water resistance test indicate that emulsion had better emulsion appearance smaller partical size,more uniform spreading and better water resistance.(4)The stability of polyurethane dispersions would be better when using S3001as the raw material while it’s mixed with VAE, the material would have better tolerance. And the hydrolysis-resistant capability can be improved when compared with common polyurethane with carboxyl group.(5)When we test the quantity proportion of the hard and soft part from1.29to2.25, the hardness of films will change from29to51HD, and the Tensile strength (over35MPa) and Elongation (over400%)would be higher.(6)When the percentage of S3001in the soft part increase, the size of the partical size decrease, which shows as a bivariate distribution function. What’s more, the solid content can be as higher as40%and the thermal stability can be improved.Because of the high cost of aliphatic aqueous polyurethane containing carboxylic and sulfonic Groups, it’s difficult to meet the market needs of different grades and also not conductive to promote the products. Therefore, instead of IPDI, this paper use TDI to produce a series of aromatic aqueous polyurethane containing carboxylic and sulfonic Groups. By the research of experimental process and characterization of the tests, the results are as follows:(1)The FT-IR proved that S3001(Mn=2000) successfully synthesized aromatic aqueous polyurethane containing carboxylic and sulfonic Groups. partical size test showed that the emulsion particle diameter was bivariate distribution.(2)The research showed that stable polyurethane emulsion could be make by adding ice water firstly and then adding EDA to extend chain slowly.(3)The tolerate test showed that adopting S3001as raw material could make the condition more stable when mixed polyurethane dispersions with VAE.(4)By adjusting the rate of change the scale of soft segment and hard segment and the rate of different dihydric alcohols in soft segment in the raw material, the hardness of polyurethane films could be changed from22HD to57HD and the films had better mechanical properties, heat resistance and hydrolysis resistance. The viscosity of the emulsion was greater than waterborne polyurethane with carboxyl group, and gradually increased with the increasing rate of S3001in soft segment(greater than80mPa·S).