Styrene Acrylonitrile (SAN): Production, Price, Market and its Properties
Styrene Acrylonitrile (SAN)
This copolymer plastic resin is a rigid transparent plastic produced by the co-polymerization of styrene and acrylonitrile. It is a combination of clarity and rigidity of polystyrene with hardness, strength and solvent resistance of polyacrylonitrile.
Styrene-based materials offer excellent qualities including durability, high performance, the versatility of designing, simplicity of production and economy. SAN products provide good hygiene, sanitation, and safety benefits. They also offer good insulation and also can be easily recycled.
It and is used primarily in automotive parts, battery cases, kitchenware, appliances, furniture and medical supplies. It is usually used in place of polystyrene due to its greater thermal resistance.
Styrene Acrylonitrile Pricing Trend
Production of Styrene Acrylonitrile
SAN consists of two units, styrene units, and acrylonitrile units in a ratio of 70 to 30. These two compounds are mixed in bulk liquid form or a solution comprising of water-based emulsion or suspension.
The process of polymerization of these compounds is conducted under the action of free radical initiators. The resultant plastic material of this process displays better resistance towards heat and solvents than an individual form of polystyrene.
Market Analysis of Styrene Acrylonitrile
SAN market size is expected to witness a growth in the coming years, owing to the development of end-user industries including cosmetics, automotive, printing, electronics etc.
The market for SAN copolymers can be segmented on the basis of regions, product, and end-user applications. These segmentations are as follows:
- North America
- Southeast Asia
- Preliminary Working SAN Resins
- Secondary Processing SAN Resins
End users/ Applications Segmentation
- Building & Construction
The demand for SAN is primarily driven by its increased application in a variety of ends user industries such as appliances, consumer goods, medical tools and other basic industries.
Consumer goods have become the fastest growing market for SAN resins. There is a large amount of demand for SAN for manufacturing consumer products such as toothbrush handle, hangers, food containers, personal computers, televisions and other handheld devices.
Increasing use of SAN co-polymers for medical applications also fuel the growth of the market. It is used for wide range of medical devices including dental equipment, medical light diffusers, and other devices.
Rising application of SAN in electronic lenses, radio, houseware, tractor components, meter covers, marine instruments, cups, dust covers, dial switches and CD players also are high driving forces of the market.
Rapid urbanization, increased income levels and infrastructural development are also boosting the demand for SAN globally. Additionally, packaging for a wide range of personal care products due to reduced product price also increase the demand for SAN polymers.
The major share of market demand for SAN polymers is held by Asian- Pacific regions where China holds the largest share due to increasing urbanization rate and high Gross Domestic Production.
Further, North America has moderate growth for San market due to market saturation. In this region, demand is driven by end users like transportation and appliances industry.
Europe dominated by France and Germany also have a significant amount of growth in the market demand of the co-polymer due to rise in appliance industries in this region.
The major restraining factor for the growth of market demand is the availability of substitutes and rising health and environmental concerns related to the use of styrene.
Other challenges faced by the industry include product commoditization, fluctuation in crude oil prices and shift of consumer choice towards the use of organic materials.
Major companies producing SAN resins are Samsung Cheil Industries, Chi Mei, INEOS, China National Petroleum, SABIC Innovative Plastics, Toray Industries, Formosa Plastics, Styron, Techno-Polymer and Petro China.
SAN is available since 1940’s and was initially introduced in the year 1950. Its increased toughness over individual styrene made it applicable for a variety of uses. Further, limitations of SAN led to introduction of butadiene (rubber) as a third monomer and resulted in production of ABS (Acrylonitrile-Butadiene-Styrene)
Properties of Styrene Acrylonitrile
SAN resins have similar usage to polystyrene. Like polystyrene, they are also optically transparent, brittle and have mechanical behavior. Some of the basic properties which this co-polymer exhibits are as follows:
- High strength and chemical resistance
- Provide good flow and dimensional stability
- Highly resistant towards heat
- Allow good flow
- Resistant towards stress cracking, grease, and food stains
- It has glass transition temperature above 100°C
- Used for general purpose (end- user plastic products)
Tensile Strength is 3.40 – 3.90 N/mm² and Notched Impact Strength is 250 Kj/m²
Thermal Coefficient of expansion is 70 x 10-6
Max Cont Use Temp for SAN is 55°C
Density is 1.08 g/cm3
Highly resistant to Dilute Acids and Alkalis
Very good resistance to oil and greases
Have a moderate amount of resistance to Aliphatic Hydrocarbons and alcohols.
These resins have poor resistance towards Aromatic Hydrocarbons and Halogenated Hydrocarbons.
Uses of Styrene Acrylonitrile
Styrene Acrylonitrile is applicable to a number of uses in a variety of industries. It is usually preferred over polystyrene due to its better properties. These resins are used in different end-segment markets including:
Electrical/Electronics Applications – They are used in televisions, cables, radio, air conditioners, computers and other person using electronic devices.
Household Goods– These resins are used in production and packaging of a variety of household goods such as detergents, containers, clothing, toothbrush and bathroom fittings etc.
Cosmetic Packaging– SAN has used a major plastic polymer for packaging of cosmetics such as in compact cases and lipstick tubes etc.
Automotive Applications– It is widely used in manufacturing number of automotive parts including automotive trim, tractor components, automotive instrument lenses and battery cases etc.
Stationary– SAN resins are used for manufacturing commonly used stationary products on daily basis such as scales, calculators, printer, writing and drawing equipment etc.
General Purpose– Physical and mechanical properties of SAN polymers make them suitable for producing a variety of general use products like bottle caps, dial switches, dust cover, marine instruments and packaging of personal care products.
Advantages and Disadvantages of Styrene Acrylonitrile
SAN polymers are often preferred over individual Polystyrene as they offer a number of benefits which are:
- Improved chemical resistance over polystyrene
- It provides better toughness and rigidity to the products manufactured.
- These polymers are dimensionally stable.
- They offer ease of processing.
It is highly resistant to chemicals and stress cracking.
Though they are commonly used plastic resins for a variety of applications, also have certain limitations such as:
- Higher water absorption as compared to polystyrene.
- Lower thermal capability and impact strength.
- High processing temperature is required,
- Yellows quickly and is flammable with high smoke generation.
The presence of Acrylonitrile in SAN polymers have been found to migrate to content in variable amounts up to some extent. They have been classified as class 2B carcinogen IARC (International Agency for Research on Cancer). It has been diagnosed as one of the cause of cancer in males and females.