A kind of water-based polyurethane emulsion with yellowing resistance and high film hardness and preparation method thereof

Abstract

The invention provides an anti-yellowing waterborne polyurethane emulsion with high glue film hardness. The anti-yellowing waterborne polyurethane emulsion is prepared from raw materials in parts by weight as follows: 60 parts of carbon dioxide copolymer polyols, 1-10 parts of a hydrophilic chain extender, 20-60 parts of aliphatic diisocyanate, 0.01-1 part of a catalyst, 0-10 parts of a non-hydrophilic chain extender, 100-300 parts of deionized water, 0.1-5 parts of a chain-extending crosslinking agent and 5-40 parts of a polyacrylate emulsion. The invention further provides a preparation method of the anti-yellowing waterborne polyurethane emulsion with high glue film hardness. The waterborne polyurethane emulsion is prepared from basic raw materials including carbon dioxide copolymer polyols and aliphatic diisocyanate through composite modification under the action of the polyacrylate emulsion and has higher glue film hardness and a higher anti-yellowing property.

Description

technical field [0001] The invention relates to a water-based polyurethane emulsion, in particular to a water-based polyurethane emulsion with anti-yellowing and high film hardness and a preparation method thereof. Background technique [0002] At present, there are two main raw materials for synthesizing water-based polyurethane—isocyanate and polyol. The traditional isocyanate is aromatic isocyanate. The water-based polyurethane prepared from it is high in strength, but has the disadvantage of easy yellowing. In recent years, aliphatic isocyanate is Waterborne polyurethane emulsions prepared from raw materials are valued for their resistance to yellowing. The polyol resins used in the synthesis of waterborne polyurethane are mainly polyether and polyester polyols. The waterborne polyurethane film prepared from polyether polyols has low strength, poor wear resistance, and poor UV aging resistance. The water-based polyurethane film prepared from polyester polyol has high st...

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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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