A kind of low-cost high-hardness aqueous polyurethane emulsion and preparation method thereof

Abstract

The invention provides a low-cost and high-hardness waterborne polyurethane emulsion. The low-cost and high-hardness waterborne polyurethane emulsion is prepared from, by weight, 60 parts of carbon dioxide copolymer polyols, 2-10 parts of a hydrophilic chain extender, 20-60 parts of diisocyanate, 0.01-1 part of a catalyst, 2-10 parts of a non-hydrophilic chain extender, 100-300 parts of deionized water, 0.5-4 parts of a chain-extending crosslinking agent and 5-40 parts of a polyacrylate emulsion. The invention further provides a preparation method of the low-cost and high-hardness waterborne polyurethane emulsion. The waterborne polyurethane emulsion is prepared by using the carbon dioxide copolymer polyols as a basic raw material and compounding and modifying the polyacrylate emulsion and high adhesive film hardness and low costs.

Description

technical field [0001] The invention relates to a water-based polyurethane emulsion, in particular to a low-cost, high-hardness water-based polyurethane emulsion and a preparation method thereof. Background technique [0002] At present, the polyol resins used in the synthesis of water-based polyurethane are mainly polyether and polyester polyols. The water-based polyurethane film prepared from polyether polyols has low strength, poor wear resistance, and poor UV aging resistance. However, the water-based polyurethane film prepared from polyester polyol has high strength, and the ester bond in polyester polyol is easily hydrolyzed, so the prepared water-based polyurethane has poor storage stability and poor hydrolysis resistance. The water-based polyurethane prepared by polytetrahydrofuran diol and polyhexamethylene carbonate diol has high strength, good hydrolysis resistance, weather resistance and heat resistance, but the high cost of raw materials limits its application r...

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Problems solved by technology

[0004] However, studies have found that pure PPC-type water-based polyurethane has the problem of poor drying speed. In addition, in order to obtain water-based polyurethane with storage stability, it is generally necessary to introduce hydrophilic groups. After the film is dried, the hydrophilic groups still have a strong Water absorption, resulting in high water absorption rate of water-based polyurethane film, easy to turn white after soaking in water, the film will appear milky white after soaking in water for 24 hours, affecting the appearance of the product, and the strength of the product is also greatly reduced

[0005] Using polyacrylate to modify water-based polyurethane emulsion is a common modification method, but the ether bond of polyether polyurethane has a weak ability to form hydrogen bonds, the hydrogen bond density of the urethane segment is relatively high, and the hard segments aggregate , resulting in the separation of soft and hard segments, it is difficult for both soft and hard segments to form good intermolecular hydrogen bonds with polyacrylate, so the synergistic effect is poor

The polyester segment of polyester polyurethane is easy to crystallize, and the hard segment carbamate is also easy to form hydrogen bonds, causing the hard segment to aggregate and form a phase-separated sea-island structure. The existence of the sea-island structure makes acrylate modification, even polyacrylate The segment contains a large number of ester bonds, and the soft and hard segments of polyester polyurethane are also difficult to form good intermolecular hydrogen bonds with polyacrylate, so the synergistic effect is also poor

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