Process Development of CO2-Assisted Polymer Compression for High Productivity: Improving Equipment and the Challenge of Numbering-Up

Abstract

The CO2-assisted polymer compression method is used herein to prepare porous polymer materials by bonding laminated polymer fiber sheets using a piston in the presence of CO2. In this work, the CO2 flow line connections were moved from the pressure vessel to the piston to increase productivity, which makes the pressure vessel free-moving and the processing time of sample introduction and removal seemingly zero. In addition, a numbering-up method suitable for CO2-assisted polymer compression is proposed and verified based on the variability of the products. The variability of the product was evaluated using porosity, which is one of the most important properties of a porous material. It is found that the CO2 exhaust process, specific to this method, that uses high-pressure CO2, causes product variation, which can be successfully suppressed by optimizing the CO2 exhaust process.

New Design Method for Fabricating Multilayer Membranes Using CO2-Assisted Polymer Compression Process

“…A sample with two separators sandwiched between three layers was set in a pressure vessel, the piston was lowered to the CO 2 introduction position, the air was replaced with CO 2 as in the first-step CAPC treatment, and then, CO 2 was introduced. Then, the piston was lowered to the press position and pressed for 10 s. In a previous study, when processing multiple samples with separators, there was a tendency for the upper sample to become thicker when CO 2 was instantly exhausted [ 16 ], so in the second CAPC treatment, V 3 was opened for 30 s, and the V 4 metering valve was used. After slow exhaustion through the valve, V 2 was opened to release the CO 2 to the atmosphere instantaneously.…”

“…After slow exhaustion through the valve, V 2 was opened to release the CO 2 to the atmosphere instantaneously. It is known that this treatment eliminates the phenomenon of the upper layer becoming thicker [ 16 ]. Regarding the thickness of each layer, the thickness of the central portion was measured using a micrometer caliper and a sample.…”

“…It has also been found that it is easy to carry a drug between sheets and that the sustained release of the drug can easily be controlled by changing the number of sheets and the compression rate [ 15 ]. Regarding the productivity concerns due to batch production, producing multiple products with a single press was successful, and further study is being conducted on the necessary procedures for mass production [ 16 ].…”

Analysis of Restitution Coefficient and Hardness of CO₂-Assisted Polymer Compression Products

“…I have studied the relationship between the process conditions, pore size, and porosity (Aizawa, 2018b), the relationship between the adhesive strength and penetration strength (Aizawa, 2019a), and the relationship between sustained drug content release and porosity (Wakui and Aizawa, 2018). In addition, I have developed a simultaneous mass production technique (Aizawa, 2019b) and another production technique for producing multilayered membranes with di erent porosities by performing CAPC treatment in two steps (Aizawa, 2020). An analysis has also been presented of the pressure loss when used as a lter (Aizawa and Wakui, 2020).…”

Correlation between the Porosity and Permeability of a Polymer Filter Fabricated via CO2-Assisted Polymer Compression

“…Moreover, in this method, the porosity and pore diameter can be controlled by the amount of raw fiber material and the pressing position [17]; via this porosity control, a drug-loaded tablet has been fabricated, successfully changing sustained drug release [18]. As for mass production, the productivity of this method can be improved by simultaneously preparing several samples with a single press [19]. A multi-layered porous structure with varying porosity has been fabricated using CAPC treatment in two steps [20].…”