Aggregation and Color Bleeding

An improvement in color bleeding has been described, however, it is necessary to add a large amount of a polymer that is geUed or thickened at a high temperature in order to exert the effect sufficiently. 

But due to the increase of the additional amount of the polymer, the ejecting performance of the ink is significantly deteriorated in many cases. The addition of the polymer tends to puU the ink like a thread and the ink may not easily become spherical. So, the latency 

This drawback can be solved to some extent by using a urea derivative as moisturizer. However, when a large amount of a urea derivative is added to the ink, the urea derivative is decomposed during the storage and ammonia is generated. In this way, the pH of the ink becomes highly alkaline and the stability decreases. 

An ink composition has been developed to solve the above-described problems. The composition contains a block pol5mcier that has an ethylene oxide moiety and a propylene oxide moiety, and is geUed at 70°C or higher. 

Specific examples of the block pol5nner include a diblock polymer of poly(ethylene oxide) and poly(propylene oxide) or a triblock co-pol5mer of poly(ethylene oxide), poly(propylene oxide), and poly-(ethylene oxide). Such block pol5mers are commercially available, e.g., NEWPOL PE-78, and PLUONIC P85. Also, apol5mer latex is added. Examples of polymers suitable for the latex are shown in Table 3.39. 

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