Method for preparing water-based polyurethane by nontoxic process

Abstract

The invention discloses a method for preparing water-based polyurethane by a nontoxic process and the water-based polyurethane prepared by the method. The method comprises the following steps: mixingdicyclohexylmethane diisocyanate with aliphatic diol in a molar ratio of 2.5 to 4, and performing reaction for 3 to 5 hours at 70 to 90 DEG C to obtain a prepolymer; adding dimethylolbutanoic acid containing a hydrophilic group, and performing reaction for 3 to 5 hours; adding an aqueous solution of KOH for emulsification and dispersion; and dropwise adding a diamine chain extender for chain extension, and dropwise adding policapram to obtain a water-based polyurethane emulsion. The method disclosed by the invention has the advantages that aliphatic isocyanate, namely dicyclohexylmethane diisocyanate and aliphatic polydiol are adopted, common organic solvents such as NMP and acetone for preparing water-based polyurethane are not added, common neutralization agents such as triethylamine arenot added, a completely-nontoxic polyurethane material can be prepared, and the polyurethane material can be widely applied to the fields of medicine and hygiene, foods and household articles.

Description

technical field [0001] The invention relates to a method for preparing water-based polyurethane, in particular to a method for preparing water-based polyurethane by a non-toxic process and polyurethane obtained by the method. Background technique [0002] Water-based polyurethane uses water as the dispersion medium. Compared with solvent-based polyurethane, it has the advantages of non-combustibility, low odor, energy saving, and convenient operation. It has been widely used as leather finishing agent, coating and adhesive. [0003] Although compared with solvent-based polyurethane, there is still a gap in the product performance of water-based polyurethane, such as water resistance. In recent years, with people's increasing requirements for health and environmental protection and the promulgation of relevant national laws and regulations, there have been many reports on the preparation and research of waterborne polyurethane. [0004] Patents CN10113A, CN1405196A, CN193025...

AI Technical Summary

Problems solved by technology

The chronic action of N-methylpyrrolidone can cause dysfunction of the central nervous system, and cause lesions of respiratory organs, kidneys and vascular systems. However, N-methylpyrrolidone has a high boiling point and is difficult to remove in the end and stays in the material. biological toxicity

Secondly, water-based polyurethane usually uses tertiary amines such as triethylamine as a neutralizing agent, and triethylamine has a strong ammonia odor and has low solubility in water. This type of water-based polyurethane will emit amine odor, which is harmful to humans during production. and the environment will cause harm, and at the same time make the product somewhat toxic

Third, most of the previous patents used aromatic isocyanates such as HDI, IPDI and TDI as raw materials. On the one hand, isocyanates such as HDI, IPDI and TDI have high vapor pressure and are volatile. It is easy to cause harm to people and the environment, and polyurethane materials made of aromatic isocyanate TDI or MDI may decompose and produce carcinogenic aromatic amines during use

However, in order to avoid the use of co-solvent NMP, the invention does not use a hydrophilic monomer-containing chain extender, and directly adds water to the prepolymer during emulsification, while vigorously stirring to realize emulsification and dispersion, or does not use a co-solvent under the condition of using DMPA. Solvent is directly used for prepolymer chain extension. Because of its poor alcohol solubility, the prepolymerization system is turbid, which is unfavorable for chain extension reaction. The disadvantage of this invention is that the emulsion prepared by it has a large particle size, and the emulsion is unstable and easy to precipitate. layered