Hydroxypropyl methylcellulose (HPMC) is a common cellulose derivative widely used in cleaning products, mainly used to adjust the viscosity, stability and rheological properties of the products. With the increasing demand of consumers for efficient and environmentally friendly cleaning products, the role of HPMC in viscosity control is becoming more and more important. However, how to effectively improve the viscosity control of HPMC in cleaning products and optimize product performance is still a topic worthy of in-depth study.

(1) Basic characteristics of HPMC
HPMC is a water-soluble nonionic cellulose ether with good thickening, film-forming, suspension and lubrication functions. Its molecular structure contains hydroxypropyl and methyl groups, which give it good solubility and stability. After HPMC dissolves in water, it forms a transparent colloidal solution, which can effectively increase the viscosity of the liquid system and prevent the precipitation of solid particles, thereby playing a stabilizing role.

In cleaning products, HPMC is mainly used as a thickener and viscosity regulator. It can give cleaning products suitable rheological properties, so that they have good coating and lubricity during use. In addition, HPMC has strong salt resistance and temperature stability, and is suitable for various types of cleaning product formulations, such as detergents, hand sanitizers, shampoos, etc.

(2) Application status of HPMC in cleaning products
Thickening effect: HPMC forms a hydrogen bond network structure in the aqueous phase to increase the viscosity of the solution, making the cleaning product have a better feel and stability. For example, in detergents, HPMC can effectively improve the consistency of the product to prevent it from being too thin and affecting the cleaning effect. At the same time, it can also improve the dispersibility of the detergent and make its dissolution rate in water more uniform.

Rheological control: HPMC can adjust the rheological properties of cleaning products, that is, the flow and deformation behavior of the product under different conditions. Appropriate rheological properties not only affect the product’s user experience, but also affect the stability of the product during storage. For example, HPMC can keep the hand sanitizer at an appropriate viscosity at low temperatures to prevent it from becoming thin or agglomerating.

Suspension and stabilization effect: In cleaning products containing solid particles, HPMC can effectively prevent the particles from settling and ensure the uniformity of the product during long-term storage. For example, detergents may contain abrasives or microparticles. HPMC increases the viscosity of the system to ensure that these solid particles are suspended in the liquid and prevent them from settling at the bottom of the bottle.

(3) Challenges in HPMC viscosity control
Although HPMC has significant advantages in viscosity control, there are still some challenges in practical applications, mainly in the following aspects:

The effect of different temperatures on viscosity: HPMC is sensitive to temperature, and its viscosity will be significantly reduced at high temperatures, which may lead to a decrease in product performance in some application scenarios. For example, in a high temperature environment in summer, the consistency of the detergent may decrease, affecting the use effect.

The effect of ionic strength on viscosity: Although HPMC has a certain salt resistance, the thickening effect of HPMC may be weakened under high ionic strength conditions, especially in cleaning products containing a large amount of electrolytes, such as washing powder and laundry detergent. In this case, the thickening ability of HPMC will be limited, making it difficult to maintain a stable viscosity of the product.

Viscosity changes during long-term storage: During long-term storage, the viscosity of HPMC may change, especially under conditions of large temperature and humidity fluctuations. Changes in viscosity may lead to a decrease in product stability and even affect its cleaning effect and user experience.

(4) Strategies to improve the viscosity control of HPMC
In order to improve the viscosity control of HPMC in cleaning products, a variety of measures can be taken, from optimizing the molecular structure of HPMC to adjusting other ingredients in the formula.

1. Optimizing the molecular structure of HPMC
The viscosity of HPMC is closely related to its molecular weight and degree of substitution (the degree of substitution of methyl and hydroxypropyl groups). By selecting HPMC with different molecular weights and degrees of substitution, its thickening effect in different cleaning products can be adjusted. For example, selecting HPMC with a larger molecular weight can improve its viscosity stability at high temperatures, which is suitable for cleaning products in summer or high temperature environments. In addition, by adjusting the degree of substitution, the salt resistance of HPMC can be enhanced, so that it maintains a good viscosity in products containing electrolytes.

2. Using a compound thickening system
In practical applications, HPMC can be compounded with other thickeners to enhance its thickening effect and stability. For example, using HPMC with other thickeners such as xanthan gum and carbomer can achieve better thickening effects, and this compound system can show better stability at different temperatures, pH values ??and ionic strengths.

3. Adding solubilizers or stabilizers
In some cases, the solubility and stability of HPMC can be improved by adding solubilizers or stabilizers to the formula. For example, adding surfactants or solubilizers can enhance the dissolution rate of HPMC in water, allowing it to play a thickening role more quickly. In addition, adding stabilizers such as ethanol or preservatives can reduce the degradation of HPMC during storage and maintain long-term viscosity stability.

4. Control the production and storage environment
The viscosity of HPMC is sensitive to temperature and humidity, so environmental conditions should be controlled as much as possible during production and storage. For example, during the production process, by controlling temperature and humidity, it can be ensured that HPMC dissolves and thickens under optimal conditions to avoid viscosity instability caused by environmental factors. During the storage stage, especially in high temperature seasons, the product should be avoided from being exposed to extreme environments to prevent viscosity changes from affecting product quality.

5. Developing new HPMC derivatives
By chemically modifying the HPMC molecule and developing new HPMC derivatives, its viscosity control performance can be further improved. For example, developing HPMC derivatives with stronger temperature resistance and electrolyte resistance can better meet the needs of complex cleaning product formulations. In addition, the development of environmentally friendly and biodegradable HPMC derivatives will also help improve the environmental performance of cleaning products and follow the current trend of green chemistry.

As an important thickener and viscosity controller, HPMC has broad application prospects in cleaning products. However, due to its sensitivity to environmental factors such as temperature and ionic strength, challenges in HPMC viscosity control still exist. By optimizing the molecular structure of HPMC, using a compound thickening system, adding solubilizers or stabilizers, and controlling production and storage conditions, the viscosity control performance of HPMC in cleaning products can be effectively improved. At the same time, with the development of new HPMC derivatives, the viscosity control of cleaning products in the future will be more efficient and stable, further improving the performance and user experience of cleaning products.