Today's KNOWLEDGE Share:CYANATE ESTER

Today's KNOWLEDGE Share

CYANATE ESTER:

Cyanate ester resins are a special class of polymeric materials whose molecules contain structural units of cyana(-CN) and carbonyl groups(-C00). Cyanate esters exhibit attractive physical, electrical, thermal, and processing properties. Blends with epoxy and bismaleimide are common.

Cyanate esters bear basically two cyanate groups (-OCN) attached to an aromatic ring. Also, aryl cyanate esters with additional allyl groups are known, e.g., 1-allyl-2-cyanatobenzene. Cyanates are formed by the reaction of phenols with cyanogen halides.

Cyanate ester resins are superior to epoxy resins, phenolic resins, and bismaleimide resins. They combine the advantages of epoxies, the fire resistance of phenolics, and the high-temperature performance of polyimides. Dicyanates of bisphenol derivatives are currently used in composites with established reinforcements such as carbon fiber, glass fiber, silica cloth, pitch-based graphite fibers.

Properties of Cyanate Ester Monomers:

Low Melt Viscosity

Good Solubility in Common Solvents

Compatible with Other Resins

Properties of Cured Resins:

High Tg

Low Thermal Expansion

Low Dielectric constant, Dissipation factor

Good Electrical Insulation

Applications:

Electronic Materials: Printed Wiring Boards for high frequency devices, Thermal Conductive Materials, etc.

Structural Materials: FRPs, Adhesives, etc.

Cyanate ester resins are currently used for many important applications such as high-temperature adhesives, and advanced composite matrices in the aerospace and automotive industry. A unique combination of properties such as high temperature stability and chemical resistance, low moisture uptake and low dielectric constant in the cured state, as well as low viscosity in the uncured state has led to their use in low-volume high-performance applications. The most common thermoplastic tougheners for epoxy systems are polysulfones (PSF), polyetherimides (PEI) or polyethersulfones (PES.

cyanate ester resins are used for high-temperature composites and adhesive applications. These systems can provide high glass transition temperatures (Tg = 170 - 350ºC), low water absorption and low dielectric properties. These products are typically used in aerospace and space applications, high-speed circuit boards, electronic chip adhesives and encapsulants, and syntactic foams.

Moisture resistance was improved by blending bisphenol A dicyanates with epoxy resins to reduce the amount of ester linkages in the resulting copolymer.

In order to enhance the moisture resistance of cyanate ester resins, modifiers containing silicon or fluorine moieties were introduced.

A high temperature resistant novolac cyanate ester was blended with polyethersulfone (PES) with different molecular weights using the solvent-free approach.

Key Players:

Huntsman

Lonza

Techia Corporation

Koniklijke TenCate

Cytec

Kuraray

Hexcel

Jiangdu Maida Group

Toray

Isola Group

Adeka

SGL Carbon

Gurit

Syensqo

Mitsubishi Gas Chemical

source:Mitsubishi