The raw material of waterborne polyurethane

The raw materials for preparing waterborne polyurethane are as follows:

(1) oligomer polyols: polyether diol, polyester diol, polyether triol, polybutadienediol, acrylate polyols, etc.The oligomer polyols commonly used in the preparation of waterborne polyurethane adhesives are generally polyether diol and polyester diol, and sometimes polyether triol, low branched polyester polyol, polycarbonate diol and other small varieties of oligomer polyols are used.Polyether polyurethane has good low temperature flexibility and water resistance, and the price of commonly used polypropylene oxide glycol (PPG) is lower than that of polyester glycol. Therefore, the development of waterborne polyurethane in China mostly takes polypropylene oxide glycol as the main oligomer polyol raw material.Polyurethane prepared from polytetrahydrofuran ether diol has good mechanical strength and hydrolysis resistance, but its high price limits its wide application.

Polyester polyurethane has high strength and good adhesion, but because the hydrolysis resistance of polyester itself is worse than that of polyether, the water-based polyester polyurethane made from common raw materials has a shorter storage stability period.However, the hydrolysis resistance of waterborne polyurethane adhesives can be improved by using hydrolysis resistant polyester polyols.The mainstream products of polyurethane emulsion adhesives and coatings abroad are polyester type.The flexibility of aliphatic non-regular structure polyester is also better. The one-component polyurethane emulsion adhesive prepared by crystalline polyester diol with regular structure has a higher initial strength after thermal activation bonding.The water-based polyurethane made from aromatic polyester polyols has high adhesion to metals, RET and other materials and strong cohesion.

Other oligomer diols, such as polycarbonate diol, polycaprolactone diol, polybutadienediol and acrylate polyol, can be used in the preparation of waterborne polyurethane adhesives.Polycarbonate type polyurethane has good hydrolysis resistance, weather resistance, heat resistance and easy crystallization. Due to its high price, its wide application is restricted.

(2) Isocyanate :TDI, MDI, IPDI, HDI, etc.The commonly used diisocyanates in the preparation of polyurethane emulsions include aromatic diisocyanates such as TDI and MDI, and aliphatic and aliphatic diisocyanates such as TDI, MDI and HDI.Polyurethanes made from aliphatic or aliphatic diisocyanates have better hydrolysis resistance than those made from aromatic diisocyanates, so water-based polyurethane products have better storage stability.Foreign high quality polyester-based waterborne polyurethane are generally made from aliphatic or aliphatic isocyanate raw materials. However, limited by the variety and price of raw materials in China, most of them only use TDI as diisocyanate raw materials.Polymethylene polyphenyl polyisocyanates are commonly used in the preparation of vinyl polyurethane emulsion and isocyanate emulsion.

(3) chain extender :1, 4-butanediol, ethylene glycol, hexanediol, ethylenediamine, etc.Chain extenders are often used in the preparation of waterborne polyurethane, among which a variety of hydrophobic chain extenders can be introduced with ionic groups. In addition to these special chain extenders, chain extenders such as 1, 4-butanediol, ethylene glycol, diethylene glycol, hexanediol, ethylenediamine and diethylenetriamine are often used.Because the reaction activity of amine and isocyanate is higher than that of water, the diamine chain extender can be mixed in water or made into ketone imine, and the chain extension reaction can be carried out at the same time of emulsification and dispersion.

(4) water: distilled water, deionized water.Water is the main medium of waterborne polyurethane adhesives. In order to prevent the influence of impurities such as Ca2 in tap water on the stability of anionic waterborne polyurethane, the water used for the preparation of waterborne polyurethane adhesives is generally distilled water or deionized water.

Water is also an important raw material for the synthesis of waterborne polyurethane. At present, prepolymer method is the main method for the synthesis of waterborne polyurethane. When the polyurethane prepolymer is dispersed in water, water also participates in chain extension.Due to the chain extension of water or diamine, in fact, most waterborne polyurethane is polyurethane-urea emulsion (dispersion). Polyurethane-urea has greater cohesion and adhesion than pure polyurethane, and the water resistance of the urea bond is better than that of the ammonia ester bond.

(5) hydrophobic chain extender: dihydroxymethylpropionic acid (DMPA), dihydroxyl semi-ester, sodium ethylenediamine ethesulfonate, diethylenetriamine, etc.A hydrophilic chain extender is one that introduces a hydrophilic group.This type of chain extender is a special raw material used only in the preparation of waterborne polyurethane.Such chain extenders often contain carboxyl groups, sulfonic groups or secondary amine groups, which, when combined with polyurethane molecules, make the polyurethane chain segment with functional groups that can be ionized.

Amber Zhang Ms.

Foreign trade 

Zhejiang Ruico Advanced Materials Co., Ltd. (Stock No.873233)

Add: No.188, Liangshan Road, Linghu Town, Nanxun District, Huzhou City, Zhejiang Province, China 313018

Phone: +86 (572) 2903236

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Website: www.ruicoglobal.com 

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