Chemical Structure of KR-470

Reactive siloxane materials, which have a cyclic siloxane structure as their main back-bone and multiple reactive functional groups in one molecule, have unique features such as stress relaxation and reduced cure shrinkage.

In the past, our product lineup included products with alicyclic epoxy groups as reactive functional groups, such as KR-470, but we have also developed products with other functional groups, such as acrylic groups, amino groups, and acid anhydride groups.
For specific product information, please contact us via our contact form or your local sales representative.

Structure Images

Benefits of Cyclic Siloxane Materials

Low cure shrinkage

Due to the stress relaxation caused by the cyclic siloxane structure, curing shrinkage can be reduced when used as a reactive binder.

High Tg

Resins modified with polydimethylsiloxane are known to be prone to Tg reduction. On the other hand, resins modified with cyclic siloxane structure do not suffer from such Tg reduction.

High heat resistance

The linear polydimethylsiloxane structure undergoes structural degradation from around 200°C due to thermal oxidation.
On the other hand, the cyclic siloxane structure, when introduced as a crosslinking point in the cured material, is not susceptible to the aforementioned oxidative degradation and exhibits good heat resistance.

Narrow molecular weight distribution (high compatibility)

In general, organofunctional group-modified polysiloxanes and silicone fluids have high molecular weights and molecular weight distributions, and therefore have strong low-polarity characteristics derived from silicone, and are insufficiently compatible with non-siloxane resin monomers.
The structure of this product is controlled by a cyclic siloxane skeleton, and its small molecular weight and narrow distribution make it highly compatible with other resin monomers.

Comparison of Curing Properties

(Not specified values)

Compatibility Comparison with General Purpose Monomer
(Mixture Weight Ratio Epoxy/Siloxane = 1/1)

Low-molecular-weight Siloxane-free

Does not generate volatile cyclic siloxanes such as octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane.

Examples of low-molecular-weight siloxane measurements

(Not specified values)

Expected Applications

• Reactive binder
• Reactive diluents
• Cross-linking agents for resin modification

Related Products

KR-470 (Alicyclic epoxy-containing cyclic siloxane tetrafunctional oligomer)
X-40-2678 (Cyclic siloxane bifunctional oligomer with alicyclic epoxy group)

For other specific product information, please contact us by using the inquiry form or contacting your sales representative.