Hydroalcoholic gel basically contains four main components: alcohol, water, rheology modifier and neutralizer. The effectiveness of disinfectants that use alcohol depends on the amount and type of alcohol. The FDA recommends the effective concentration of ethanol in disinfection products: 60-95 v/v%; or 70-91.3 v/v% of isopropanol.

Alcohol can destroy the lipid-containing cell membranes of bacteria and fungi and denature the proteins and enzymes in bacteria and fungi.

1. Carbomer's choice

Although all carbomers can thicken the hydroalcoholic system, there are several grades of products that have the advantages of higher clarity, higher efficiency, easier operation and more beautiful hand washing gels. Our Carbomer 10/20/2020/21 are good rheology modifiers for these gels. A typical hand washing gel contains less than 40% deionized water. Due to this limitation, low dispersion viscosity, and ease of handling, Carbomer 10/20/2020/21 polymers are very suitable for these types of formulations compared to traditional Carbomer polymers.

2. Recipe making process

The typical formula is shown in Table 1:

For traditional carbomer such as Carbomer 980, 940, 941, 934, 1342 and other polymers: these polymers can be dispersed in water or alcohol/water mixture. When added to an alcohol/water mixture, the polymer will swell more slowly, so care must be taken to avoid agglomeration and peeling during the dispersion process.

①. Carefully disperse the polymer in water or water/alcohol mixture while stirring thoroughly. High stirring speed is usually preferred because it prevents the polymer from agglomerating on the water surface. Mix until the polymer is hydrated and dispersed evenly without lumps.

②. If ethanol is not added in step 1, add ethanol slowly and mix to degas the formula.

③. You can add emollients if necessary. Remember that the order of addition may be critical to maintaining the clarity of the product.

④. Add appropriate neutralizer, stir gently, and stir evenly.

For improved Carbomers such as Carbomer10/20/21/2020 polymers:
①. Disperse the carbomer in water, then stir until smooth to ensure no lumps and uniform dispersion.
②. Slowly add alcohol and continue to stir until the water is evenly mixed.
③. You can add emollients if necessary. Remember that the order of addition may be critical to maintaining the clarity of the product.
④. Add appropriate neutralizer, stir gently, and mix well.
If the constraints of the production equipment require that water and ethanol must be mixed before the carbomer is dispersed, it must be dispersed like a traditional polymer. Carbomer polymer does not self-wet in water and ethanol solutions.

3. Water source: use deionized water

Carbomer polymer is very sensitive to hard water ions. Therefore, if ordinary tap water is used, its transparency and viscosity may be negatively affected. If there is no deionized water, chelating agents such as EDTA can be added, and the dosage is about 0.05-0.10%(wt/wt%).

4. Add emollients

Several commercially available moisturizers can be added to hand sanitizers to compensate for the removal of alcohol from the hands. Water-soluble emollients can be added directly to the water and carbomer dispersion, or added before neutralization.

The amount of emollient used at 0.3-0.5 wt% will not affect the clarity of the final product.

5. Transmittance

All carbomer polymers have good transparency in hydroalcoholic systems. The light transmittance is affected by many factors, including dispersion technology, water source, emollient content, pH value, fragrance type and added amount of dye. In order to obtain the best light transmittance, we recommend the following:

• Use deionized water.

• Use the direct method for carbomer dispersion. When using self-wetting carbomer polymers, they should be dispersed in water, not a water/ethanol mixture.

• Choose the right neutralizer.

•Set a proper pH value: We recommend the following pH values: for Carbomer 10, 940 and 980, the optimal pH value is generally around 7.0.

• Choose water-soluble emollients.

• Use water-soluble dyes.