AccuSizer 780系列儀器在噴墨墨水粒度檢測中的應用

時間：2015-6-24 閱讀：2616

綜述

噴墨墨水的色素是在溶液中呈膠態分布的。色素的一定分散對避免沉降、不穩定或結塊引起的噴墨失敗都是很有必要的。為了確保*配比并生產，我們需要一個可靠的方法來確定終產品的粒度分布。PSS的AccuSizer系統——單顆粒計數原理(SPOS)是一個理想的工具，它可以測出噴墨墨水是否包含任何可能構成阻塞噴射器、導致性能降低等風險的粒子。本應用闡述了AccuSizer在解決噴墨墨水制造業方面問題的一些例子。

引言

The pigments formulated into inkjet inks are typically dispersed to small particle sizes (between about 50 and 200 nm, depending on the application) and need to be made colloidally stable. The colloidal stability can be achieved either by surface modification to form an adequate surface charge (zeta potential), or by adsorption of certain compounds on the surface of pigment particles (steric stabilization).

將色素按配方加入到墨水中通常要分散成小顆粒形式（大約在50到200nm之間，根據應用不同而變化）并且需要呈膠態穩定。這種膠體穩定狀態可以通過修飾表面形成適當的表面電荷（Zeta電位）來實現，也可以通過色素顆粒表面吸附一定量的化合物（空間穩定性）實現。

The size of the pigment particles is critical because large particles may plug the jets and channels, causing damage to the print head. Controlling the large particle content (> 0.5-1.0 μm) requires having a technique that is sensitive to a small number of large particles—the tail of the distribution.

色素顆粒的大小非常重要，因為大顆粒會阻塞噴射器和通道，對印刷頭造成損害。對大顆粒 (> 0.5-1.0 μm) 含量的控制就需要一個對極少量大顆粒敏感的方法——尾部大顆粒的分布

Particle Sizing and Counting Techniques

顆粒大小和計數方法

There are several methods for determining the mean particle size of ink dispersions such as dynamic light scattering (DLS), but most are not capable of determining small amounts of oversized material. Methods that are based on sizing and counting individual particles are particularly well-suited for this type of analysis, where even small amounts of outliers are sized and counted in the process.

有很多方法可以測定油墨分散體的平均粒度，比如光散射法(DLS)，但是這里的大多數方法并不能測定出少數的大顆粒。而基于單顆粒計數的方法就特別適合這類分析，測試中甚至可以測出極少量異常值的大小和數量。

The AccuSizer single particle optical sizing (SPOS) system is ideal for quantifying the size and concentration of large particle tails present in inkjet inks. Depending on the sensors incorporated the system can cover a

dynamic range of 0.15400 μm. The system shown in Figure 1 includes the standard LE400 light extinction and scattering sensor that measures from 0.5400μm mounted in the AD sampler that provides automated dilution of the sample to the optimum concentration for the measurement.

AccuSizer的單顆粒計數技術(SPOS)可以很好地對油墨中大顆粒定量大小和濃度，具體取決于傳感器的檢測范圍。系統如圖1所示，包括標準的LE400消光和散射傳感器——可以測定加入到可自動稀釋樣液的AD采樣器的0.5-400μm之間的顆粒，也可以測定試驗的*濃度。

圖1：AccuSizer 780 AD

Application Example 1: Effect of Stirring

應用實例1：攪拌的作用

There are many factors that can impact pigment dispersion one of which is stirring time. It is necessary to determine an optimal stirring time to reduce the number of oversized particles within a dispersion. It is also important to monitor stirring time since over homogenization can lead to increased particle size.

有很多因素會影響色素的分散，其中之一就是攪拌時間，因此，很有必要設定一個*攪拌時間以減少分散系中的超大顆粒。同時對攪拌時間的控制也很重要，因為過度均質會導致粒度增大。

Two pigment dispersions, magenta and cyan, were analyzed to monitor the effects of stirring time on oversized particles. The figures 2 and 3 show the results for the magenta sample that was stirred for 50, 70 and 90 minutes. The tail particles decreased from 4 x 106 particles/mL to 2 x 105 particles/mL.

我們用兩種色素分散液樣品—紅色和藍色溶液，來研究攪拌時間對超大顆粒的影響。圖2和3顯示了紅樣液分別攪拌50、70和90min的結果。尾部顆粒從4 x 106 particles/mL減少到了2 x 105 particles/mL。

Figure 2: Effect of stirring on magenta sample

圖2：攪拌對紅色溶液的影響

Figure 3: Expanded view of magenta sample

圖3：品紅溶液結果的放大圖

Concentration of large particles > 1 μm:

大于>1μm顆粒的濃度：

50 min: 4 x 106 particles/mL

70 min: 5 x 105 particles/mL

90 min: 2 x 105 particles/mL

The cyan sample shown in Figure 4 also undergoes a decrease in the number of oversized particles with stirring time. The concentration of particles decreases from 9 million particles/mL to approximay 3 million particles/ mL with just 10 additional minutes of stirring.

圖4所示的藍色溶液，同樣存在隨著攪拌時間延長而超大顆粒減少的現象。多攪拌了10min，顆粒濃度就由9 x 106 particles/mL減少到大約3x 106 particles/mL。