水性聚氨酯乳液性能
Properties of waterborne polyurethane emulsion
介質(zhì)水中聚氨酯微粒的粒徑大小對(duì)乳液的穩(wěn)定性、成膜性、對(duì)基材的濕潤(rùn)性能、膜性能及粘接強(qiáng)度等性能有較大影響。在配方基本不變、親水性基團(tuán)含量基本相同的情況下，乳液粒徑的減小，有利于提高乳液的穩(wěn)定性和膠膜性能。乳液穩(wěn)定性還與親水基團(tuán)含量和乳液顆粒表面的離子基團(tuán)有關(guān)。表面張力是關(guān)系到水性聚氨酯對(duì)基材濕潤(rùn)性的重要因素。水性聚氨酯的表面張力一般在 0.040-0.055N/m范圍。為了有效地使水性聚氨酯均勻涂覆在塑料等低表面能物質(zhì)的表面上，可添加潤(rùn)濕劑以降低乳液的表面張力。水性聚氨酯的黏度對(duì)固含量的依賴較大，黏度主要與樹(shù)脂的離子電荷數(shù)量、顆粒結(jié)構(gòu)等因素有關(guān)?？梢愿鶕?jù)施工方式和用途對(duì)水性聚氨酯的黏度進(jìn)行調(diào)整，如使用增稠劑等。
The particle size of polyurethane particles in aqueous medium has a great influence on the stability, film-forming properties, wetting properties, film properties and bonding strength of the substrate. When the formula is basically unchanged and the hydrophilic group content is basically the same, the decrease of emulsion particle size is beneficial to improve the emulsion stability and adhesive film performance. The stability of emulsion is also related to the content of hydrophilic groups and the ionic groups on the surface of emulsion particles. Surface tension is an important factor that affects the wettability of waterborne polyurethane to substrate. The surface tension of waterborne polyurethane is generally in the range of 0.040-0.055N/m. In order to effectively apply waterborne polyurethane on the surface of plastic and other low surface energy substances, wetting agent can be added to reduce the surface tension of emulsion. The viscosity of waterborne polyurethane depends greatly on the solid content, and the viscosity is mainly related to the number of ionic charges and the particle structure of the resin. The viscosity of waterborne polyurethane can be adjusted according to the construction methods and uses, such as thickening agent.

水性聚氨酯成膜性能
Properties of waterborne polyurethane film
水性聚氨酯干燥后，具有彈性體的外觀和性能。由于聚氨酯原料的多樣化，由水性聚氨酯也能制得從軟質(zhì)到硬質(zhì)的干膜。通過(guò)熱處理，一般能提高膠膜的強(qiáng)度和耐水性能，在乳液中添加交聯(lián)劑一般也能提高膠膜強(qiáng)度，但有時(shí)會(huì)降低其延伸率。水性聚氨酯樹(shù)脂一般含有親水性基團(tuán)。在干燥固化過(guò)程中，若離子型聚氨酯的成鹽劑能夠逸出，則膠膜會(huì)獲得一定的疏水性；如果成鹽劑不能夠逸出，親水性基團(tuán)殘留，并且成膜時(shí)未發(fā)生基團(tuán)之間的交聯(lián)反應(yīng)，則膠膜耐水較差。
After drying, waterborne polyurethane has the appearance and properties of elastomer. Because of the variety of polyurethane raw material, the dry film from soft to hard can be prepared by waterborne polyurethane. Generally, the strength and water resistance of the adhesive film can be improved by heat treatment. The addition of crosslinking agent in the emulsion can also improve the strength of the adhesive film, but sometimes it will decrease its elongation. Waterborne polyurethane resins generally contain hydrophilic groups. In the dry curing process, if the ionic polyurethane salt forming agent can escape, then the film will obtain certain hydrophobicity; if the salt forming agent can not escape, hydrophilic groups and residual film without crosslinking reaction between the groups, while the film water resistance is poor.

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