膨润土在水基铸造涂料悬浮率和粘度
Suspension rate and viscosity of bentonite in water based casting coating
 

　　本实验研究了钠基膨润土、羧甲基纤维素钠（CMC）、白乳胶和三聚磷酸钠对水基铸造涂料悬浮率和粘度的影响以及它们之间的交互作用。

　　实验表明：钠基膨润土、CMC可以显著提高涂料的悬浮率和粘度；白乳胶则降低涂料的悬浮率，但提高其粘度；三聚磷酸钠既降低涂料的悬浮性率又降低其粘度。发现它们之间存在对涂料悬浮率的交互作用，而对其粘度则无交互作用。

　　水基铸造涂料价格低廉、安全可靠、性能稳定、运输方便、清洁无污染，在砂型铸造、金属型铸造、离心铸造、消失模铸造等方面都有着广泛应用，是未来铸造涂料发展方向之一。在水基铸造涂料生产中，最常用的无机悬浮剂有钠基膨润土，有机悬浮剂有羧甲基纤维素钠（CMC），增稠剂有白乳胶，粘结剂有三聚磷酸钠。但关于这些助剂材料对涂料最重要的技术指标———悬浮率和粘度的影响及其交互作用的研究。本次选用中性的铝矾土作水基涂料的骨料，研究了钠基膨润土、CMC、白乳胶和三聚磷酸钠等助剂对涂料悬浮率和粘度的影响，为水基铸造涂料的研究提供参考。

　　实验材料及方法：铝矾土，320目；钠基膨润土；羧甲基纤维素钠（CMC）；三聚磷酸钠；白乳胶；润湿剂：OP-10；消泡剂：JFC。

　　涂料悬浮率采用100mL圆柱量筒，静置6、24h澄清法；其粘度采用100mL、准6mm流杯法。将钠基膨润土、白乳胶、CMC、三聚磷酸钠在使用前，用特定工艺引发、溶解，制成浆料，72h后使用。

　　结论：

　　1、白乳胶显著提高涂料的粘度，但是降低涂料的悬浮率；钠基膨润土和CMC提高涂料的悬浮率和粘度；三聚磷酸钠既降低涂料的悬浮率，又降低其粘度。

　　2、从这4种助剂对涂料的悬浮率和粘度的影响规律看，涂料的悬浮率和粘度之间没有对应的关系。

　　3、三聚磷酸钠和钠基膨润土、三聚磷酸钠和白乳胶、钠基膨润土和CMC之间对涂料悬浮率有交互作用，而对其粘度无交互作用。

　　4、考察涂料6h悬浮率时，CMC和钠基膨润土之间是加强的交互作用铜陵，铜陵膨润土生产销售三聚磷酸钠和钠基膨润土、三聚磷酸钠和白乳胶之间是减弱的交互作用。

　　The effects of sodium bentonite, sodium carboxymethyl cellulose (CMC), white latex and Sodium Tripolyphosphate on the suspension rate and viscosity of water-based casting coatings were studied.
　　The results show that: sodium bentonite and CMC can significantly improve the suspension rate and viscosity of the coating; white emulsion adhesive can reduce the suspension rate of the coating, but increase its viscosity; sodium tripolyphosphate can reduce the suspension rate and viscosity of the coating. It is found that there is an interaction between them on the suspension rate of the coating, but no interaction on its viscosity.
　　Water based casting coating is cheap, safe and reliable, stable performance, convenient transportation, clean and pollution-free. It is widely used in sand casting, metal mold casting, centrifugal casting, lost foam casting and so on. It is one of the development directions of casting coatings in the future. In the production of water-based casting coating, the most commonly used inorganic suspending agent is sodium bentonite, the organic suspending agent is sodium carboxymethyl cellulose (CMC), the thickener is white latex, and the binder is sodium tripolyphosphate. However, the influence of these additives on the most important technical indexes of coatings, suspension rate and viscosity, and their interaction are studied. In this paper, neutral bauxite was selected as the aggregate of water-based coating. The effects of additives such as sodium bentonite, CMC, white latex and Sodium Tripolyphosphate on the suspension rate and viscosity of the coating were studied, providing reference for the research of water-based casting coating.
　　Materials and methods: bauxite, 320 mesh; sodium bentonite; CMC; sodium tripolyphosphate; white latex; wetting agent: OP-10; defoamer: JFC.
　　The suspension rate of the coating was 100 ml cylinder, which was clarified by standing for 6 and 24 h, and its viscosity was determined by flow cup method of 100 ml and quasi 6 mm. Sodium bentonite, white latex, CMC and sodium tripolyphosphate were used to initiate and dissolve before use, and then the slurry was prepared and used 72 hours later.
　　Conclusion：
　　1. The results show that white latex can significantly improve the viscosity of the coating, but reduce the suspension rate of the coating; sodium bentonite and CMC can improve the suspension rate and viscosity of the coating; sodium tripolyphosphate can reduce the suspension rate and viscosity of the coating.
　　2. According to the influence of the four additives on the suspension rate and viscosity of the coating, there is no corresponding relationship between the suspension rate and viscosity of the coating.
　　3. There is interaction between sodium tripolyphosphate and sodium bentonite, sodium tripolyphosphate and white latex, sodium bentonite and CMC, but no interaction on its viscosity.
　　4. The interaction between CMC and Na bentonite is strengthened when the suspension rate of coating is investigated for 6h. The interaction between sodium tripolyphosphate and sodium bentonite,sodium　tripolyphosphate and white latex is weakened in Tongling bentonite production and sales.