1.Introduction

Super absorbent Polymer (SAP) is a functional polymer material with an extremely strong water absorption and retention capacity. It can absorb hundreds or even thousands of times its own weight in water and is not easily released under pressure. Since its development by the United States Department of Agriculture in the 1960s, SAP has been widely applied in fields such as hygiene products, agriculture, healthcare, and industry. This article will deeply explore the characteristics, production process, main applications and future development trends of SAP.

2.Characteristics of SAP

The core features of SAP include:

Ultra-high water absorption: It can absorb pure water up to 500 to 1000 times its own weight and physiological saline (0.9% NaCl) about 50 times.

Strong water retention: It forms a gel after absorbing water and can lock in moisture even under pressure conditions (such as diapers).

Biocompatibility: Some medical-grade SAP can safely come into contact with human tissues.

pH sensitivity: Some modified SAP can respond to changes in environmental pH values and is used for sustained drug release.

Chemical composition

The main raw materials of SAP include:

Sodium Polyacrylate: The most common type, accounting for more than 90% of the global SAP production.

Starch grafted acrylate: Biodegradable, suitable for environmental protection fields.

Polyvinyl alcohol (PVA) -based SAP: For special industrial scenarios.

3.The production process of SAP

The industrial production of SAP mainly adopts solution polymerization method or reverse suspension polymerization method. The key steps are as follows:

Monomer mixing: Acrylic acid (AA) is neutralized with sodium hydroxide to form sodium acrylate.

Polymerization reaction: Add a crosslinking agent (such as N,N' -methylene diacrylamide) and an initiator (such as potassium persulfate), and polymerize at 50 to 80 degrees Celsius.

Drying and crushing: The product is dried and then crushed into particles, with particle sizes typically ranging from 100 to 800 microns.

Surface crosslinking: Enhance gel strength through secondary crosslinking (for high-end hygiene products).

4.Main applications of SAP

4-1.Hygiene products (the largest application market)

Baby diapers: SAP replaces traditional fluff pulp, making the product thinner and lighter and having a stronger liquid absorption capacity.

Adult incontinence products: In response to the demands of an aging society, the market is growing rapidly.

Female sanitary napkins: Enhance comfort and leak-proof performance.

4-2. Agriculture

Soil water-retaining agent: In arid areas, it reduces the frequency of irrigation when planting and increases the survival rate of crops.

Seed coating: Provides continuous moisture for seed germination.

4-3. Medical field

Medical dressings: Absorb exudate from wounds and promote healing.

Drug sustained-release carriers: Control the release rate of drugs in the body.

4-4. Industrial uses

Cable waterproofing: A water-blocking hose used for optical cables and cables.

Wastewater treatment: Adsorb heavy metal ions or organic pollutants.

5.Current Market Situation and Development Trends

Market size

The global SAP market size was approximately 12 billion US dollars in 2023 and is expected to exceed 18 billion US dollars by 2030 (CAGR 5.8%).

Main producers: BASF, Nippon Shokubai, Evonik, Satellite Chemical (China).

Technology trend

Bio-based SAP: Using starch and cellulose as raw materials, it reduces reliance on petroleum-based acrylic acid.

High cost-performance SAP: Emerging markets (such as India and Africa) drive the demand for low-cost products.

Functional modification: Development of high-end products such as antibacterial SAP and ph-responsive SAP.

Challenge

Environmental issue: Traditional polyacrylic acid (SAP) is difficult to degrade, and it is necessary to develop recyclable or biodegradable alternatives.

Fluctuations in raw materials: The price of acrylic acid is significantly influenced by the crude oil market.

6.Conclusion

SAP, as a revolutionary functional material, plays an irreplaceable role in the fields of people's livelihood and industry. In the future, with stricter environmental regulations and technological innovation, degradable SAP and high-performance specialty SAP will become the key driving forces for industry growth. Enterprises need to pay attention to the demands of sustainable development and optimize production processes in order to seize the opportunities in emerging markets.