Quantitative Analysis of Water Dispersion Conditions and Pressure Transmission Characteristics of a Wet Kneaded Mass.

Abstract

Kneading of powdered materials [1][2][3] has been widely used in the pharmaceutical, agriculture, food, chemical, forage and fertilizer industries. Most of the cases, kneading is conducted before the granulation and molding processes, and the performance of kneading seriously affects the quality of the final product or process efficiency. Therefore, it is very important to quantitatively monitor kneading conditions during the kneading operation. With the present technical levels, however, most operations in the manufacturing process are controlled by an expert's decisions, relying on empirical knowledge based on past experience involving "a sense of feeling determined by the hand".In the previous study, we developed a compression tester to measure pressure transmission among a wet kneaded mass.4) It has been demonstrated that the pressure transmission can predict the water dispersion condition among the mass, the degree of kneading attained, and properties of dry pellets prepared by extrusion granulation after the kneading. In the kneading operation, a binder should be used and its additional weight varies depending on the applications. The binder additional methods (solution or powder) and properties of starting materials (soluble or sparingly soluble to water) seriously affect the water dispersion as well as the kneading condition during the kneading. Therefore, it is very important to investigate the effects of these parameters on the water dispersion, kneading condition and on the properties of final dry pellets. However, there has been no research that has studied the effect of binder on the water dispersion, much less on the final products' qualities.The present study investigates the effects of binder content, its methods of addition and properties of starting materials on the water dispersion, pressure transmission characteristics of wet kneaded masses and on the properties of the dry pellets obtained through extrusion granulation after kneading. The mechanism of water dispersion during the paddle kneading is also discussed.

Development of a Novel Compression Tester and Rheo-Mechanical Properties of Wet-Mass Powder. I-Effect of Kneading Time on the Rheo-Mechanical Properties-

“…After the kneading, the kneaded wet-mass powder was extruded through an extrusion granulator (DG-L1, Fuji Paudal, Co., Ltd.), which consisted of a hemispherical dorm type punching screen (diameter of the dome was 58 mm, diameter of each hole and width of the screen were both 0.8 mm, and the opening area ratio was 22.5%), a single shaft with screws and an extrusion blade at the extremity of the shaft. 1,8) The dry product (pellets) was finally obtained after a fluidized bed drying (NQ-125, Fuji Paudal, Co. Ltd.) 9) of wet extruded pellets under the air temperature of 353 K. Physical properties of the dried pellets were evaluated by their strength and dissolution time (the method for measuring the granule strength and dissolution time was the same as previously reported 1) ).…”

Rheological Analysis and Quantitative Evaluation of Wet Kneaded Wax Matrix

“…The decrease in the standard deviations of moisture content means that water is more uniformly dispersed among the wet kneaded mass with the elapsed time of rotating blade accompanied with shear of stress. Watano et al [11][12][13] also reported the improvement of uniform water dispersion during the kneading process, and Evrard et al 16) reported the evolution of the product temperature during the melt granulation process in the high-shear mixer. The findings shown in Fig.…”

“…Watano et al [11][12][13] have recently demonstrated that properties of the wet kneaded mass are directly characterized by internal pressure transmissions which are determined by using a newly developed compression tester instead of the torque rheometry. Furthermore, it was also documented that the pressure transmissions were strongly associated with water dispersion among the wet kneaded mass.…”

“…Nevertheless, few reports have focused on the related properties of the wet kneaded mass to the dissolution of sustained-release drug despite of the fact that many different types of sustained-release dosage forms are urgently needed by medical circles to improve clinical efficacies and relevant patient compliance. 10) Watano et al [11][12][13] have recently demonstrated that properties of the wet kneaded mass are directly characterized by internal pressure transmissions which are determined by using a newly developed compression tester instead of the torque rheometry. Furthermore, it was also documented that the pressure transmissions were strongly associated with water dispersion among the wet kneaded mass.…”

Determination of Optimal Formulation for Extrusion Granulation by Compression Test of Wet Kneaded Mass

“…11) Watano et al evaluated the water dispersion of a wet kneaded mass using a compression test and predicted the properties of the final extruded products. 12) They also analyzed the rheo-mechanical properties of wet powder. 13,14) Meanwhile, several studies on the prediction of optimal formulations have been made.…”