Carbomer 940 is a high-molecular polymer cross-linked with acrylic acid and propylene sucrose or propylene pentaerythritol. Carbomer was first produced by Goodrich Company of the United States under the trade name Carbopol. The appearance is white loose powder with moisture absorption Sexual and characteristic slight odor, soluble in water, ethanol, glycerin, because the molecule contains 56%-58% carboxyl group, so it is weakly acidic, carbomer is an excellent medicinal auxiliary, widely used in cosmetics In the production of pharmaceuticals, carbomer is mainly used as a thickener, adhesive, gel, suspension base and matrix material for controlled-release preparations in pharmaceuticals. There are many models of carbomer, the most widely used is carbomer 940.
When we prepare carbomer 940 gel, various problems will occur. The most common thing is to generate a lot of bubbles. Many people take it for granted that defoamers can be added, but we have to consider from the perspective of drug safety. Don't use the auxiliary materials that may have safety risks to solve the problems that are solved by improving the production process. Use stirring and vacuum emulsifiers to solve them first. It is really impossible to use other methods.
1. Bubbles: The swelling carbomer first disperses the powder in water with a high-speed mixer, and there are also two methods of stirring while adding, but in the experiment, it was found that both will generate a large number of bubbles. In addition, when the carbomer swells into a colloid Later, when dissolving the related drugs, a large number of bubbles will also be introduced.
We can use the following methods to solve:
①Pre-soaking method: 24 hours in advance, first add carbomer in deionized water to dissolve according to the actual production requirements, without stirring, after carbomer naturally absorbs water, there is no white powder on the surface, and no white solution The agglomerates are subject to mixing. After mixing, add a neutralizer to adjust the PH value to about 7 to achieve a thickened state. Stir evenly with a disperser at a low speed.
②Homogenizer: Add to the homogenizer according to the actual production ratio to homogenize so that no white balls can be seen, then add a neutralizer and wait for the gel to form, then use a vacuum emulsifier to evacuate the air from the gel.
2. Produce flocculation and affect transparency: In some gels, in order to increase permeability, antiseptic, and solubilization, ethanol is often added as an additive, such as disinfection and no-clean gel, in which ethanol is the main component, the content may be up to about 75% . Carbomer gel is essentially an aqueous polymer solution. The reason why the polymer solution is stable is because of the presence of a hydration film on the surface of the particle. The addition of a strong hydrophilic non-electrolyte (such as ethanol) will cause the polymer solution to flocculate. Carbomer ethanol gels are prepared by different operating processes. The ethanol concentration of the finished product has different high limits. When the ethanol concentration is too high, the finished gel will produce a little opalescence, which reduces the transparency of the gel. However, if the ethanol content is 70%, In the finished rubber product, slowly add 2% purified water and stir. Compared with the finished product before the addition, the opalescence is significantly reduced. This method has a certain effect on improving the appearance transparency of the finished product.
Desheng warm reminder: The dispersion time of carbomer 940 in water is related to the water temperature and water quality. It is recommended to use deionized water to make the product more stable. It will take longer to dissolve in organic solutes. The carbomer 940 takes about 8 hours to soak. The specific dissolution time is related to the amount of dissolution.
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