Hydroxypropyl methyl cellulose (HPMC) is a cellulose derivative that was first developed and used in industrial and food applications starting in the 20th century. Its exact origin in terms of discovery and initial development is difficult to attribute to a single individual or organization, as research and development of cellulose derivatives has involved many scientists and companies at different times.

HPMC is produced through a chemical process known as etherification, in which natural cellulose is treated with hydroxypropyl chloride and sodium methoxide. This process alters the chemical structure of cellulose, making it water-soluble and giving it desired properties as a thickener, stabilizer and film-forming agent.

Production and Use over Time:

The use of HPMC in industrial and food applications has grown significantly since the mid-20th century, when researchers began to more fully explore the potential uses of cellulose derivatives. Its ability to act as a thickener, emulsifier and stabilizer has increased its adoption in a variety of industries, including pharmaceuticals, cosmetics and food.

HPMC was first discovered in 1891, but it wasn't until 1951 that the pharmaceutical industry started using HPMC in its products. It was recognized as a safe drug delivery system when it was used with other drugs that were poorly absorbed or eliminated from the body. In 1967, HPMC was approved by the FDA for use in over-the-counter medicines such as cough syrups and throat sprays, as well as topical creams and gels for the treatment of minor burns and skin conditions such as eczema or psoriasis. In today's world, many consumers are using natural remedies on their skin or seeking alternative treatments for chronic diseases such as diabetes, heart disease, and high blood pressure. 

2. The viscosity of Hydroxypropyl Methylcellulose is related to the size of the molecular weight, and the larger the molecular weight is , the higher the viscosity is. The temperature will also affect its viscosity. As the temperature increases, the viscosity decreases. However, the viscosity of Hydroxypropyl Methylcellulose is less affected by the temperature than Methyl Cellulose, and its solution is stable in storage at room temperature.