Tuesday, May 22, 2012

All about MR Series...(MR-8, MR-7, MR-10, MR-174)

"Mitsui Chemicals is a Japanese Chemicals company. The company mainly deals in performance materials, petro and basic chemicals and functional polymeric materials."

What is MR Lenses: (MR-8, MR-7, MR-10, MR-174)
    Excellent optical materials with high refractive index, high Abbe number, low specific gravity and high impact resistance are provided by polymerizing monomers of MR™ Series. MR™ Series is especially suitable for ophthalmic lenses and is known as the first thiourethane based high index lens material. MR™ Series offers a variety of products to provide the best solution for optical lens users.
R.I. 1.60: MR-8™
The best balanced high index lens material with the largest share of the R.I. 1.60 lens material market.
MR-8™ is suited to any strength ophthalmic lens and is a new standard in ophthalmic lens material.

 R.I. 1.67: MR-7™ & MR-10™
Global standard R.I.1.67 lens material.
Great materials for thinner lenses with strong impact resistance.
Material Characteristics
MR-7™   : Better color tintability
MR-10™ : Higher heat distortion temperature

 R.I. 1.74: MR-174™
Ultra high index lens material for ultra thin lenses.
Strong prescription lens wearers are now free from thick and heavy lenses.

MR™ Series is a brand name of the raw material for optical lenses.
MR™ Series based lenses are available from most leading lens manufacturers.
Comparison of physical properties of lenses made with MR™ Series vs. other optical materials
MR™ SeriesOther
Temp. (ºC)
Static Load

MR Series Features:
  • High refractive index for thinner and lighter lenses.
MR™ Series offers 3 different refractive index products (R.I. 1.60, 1.67, 1.74).
With higher index materials, it is possible to achieve thinner lenses with the same strength.
  • Superb optical quality for wearer comfort
  • Both high refractive index and high Abbe number provide optical performance similar to glass lenses.
  • Glass mold-casted MR™ Series shows minimal stress-strain.

High Abbe number material like MR-8™ minimizes prism effect (Chromatic aberration) of lenses and provides comfortable view to all wearers.

High Abbe Number Material
image Abbe Number
Low Abbe Number Material
image Abbe Number
MR™ Series resin is uniformly polymerized in a glass mold. Compared to the injection molded Polycarbonate lens, MR™ Series lens shows minimal stress strain and offers stress free clear vision.
Stress Strain Observation
(Crossed Nichol method using the polarizing film and white light source)
image Strain Free

  • Mechanical strength to protect wearers from accidental injury. 

  • High impact and static load resistance helps promote wearer eye safety.
    (Pass US-FDA drop ball test standards)
  • Good tensile strength for fashionable rimless frames.
  • Good processability for precisely designed progressive lenses (Advantage of thiourethane materials) .
Mechanical Strength
Impact Resistance
  • High impact resistance of MR-8™ helps protect wearers form accidental injury.
FDA Drop Ball Test
MR-8™ shows good impact resistance
US-FDA (Food and Drug Administration) Sec. 801.410
“Use of impact-resistant lenses in eyeglasses and sunglasses”

Static Loading Resistance
Static Loading Test
Quasi-static loading type test for minimum robustness
MR-8™ shows good static load resistance
 Tensile Strength Resistance

  • MR-8™ lens shows good tensile strength.
  • MR-8™ is widely recognized as the best material for rimless frames.
Tensile Test
Tensile test results
MR-8™ lens broke at 72kg tensile force
(All other material lenses broke at smaller forces)
Lens deformation
MR-8™ lens showed no deformation of drilled hole
(60kgf Tensile Force)
 Butterfly Test

  • MR-8™ is adequate for the long time usage of rimless glasses.
“ Butterfly Test ”for Rimless Frames
Endurance test under cyclic
load for spectacle frames
JIS B7283
Broke at 20,000 strokes

  • Durability during long time usage under severe conditions
  • Good weatherability provides minimal change in lens color after years of usage.
  • Good compatibility with coating materials.
Lens Color Change
Weatherbility Test
Accelerated test to observe lens color change after long-term usage.
QUV Test: 0.50W/m2, 50ºC, 100hrs
MR-8™ shows only minor color change after exposure to strong UV light.
Wearers can enjoy clearer lenses after long-term usage.
 Coating Compatibility
Heat Resistance Test
Evaluation of cracks in coating after high temperature conditions.
Test condition: 90ºC, 15 min.
Test condition: 80ºC, 15 min.
Good heat resistance and coating compatibility of MR-8™ prevent coating cracks under servere conditions.
 Coating Compatibility
Cross-cut Adhesion Test
1) Cut a coating layer in a reticular pattern.
2) Apply tape over the pattern and then remove it.
MR-8™ showed very good compatibility with coating materials.
Lens wearers can enjoy unchanged high performance lens coating after long-term usage.

How the MR lenses are produced?

1. Preparation of MR™ Series
illust_Preparation of MR™ Series
Mix MR™ monomer (component) A & B with additives, then degas the MR™ monomer mixture.

2. Filling
Fill molds with the MR™ monomer mixture.

3. Polymerization
Place the filled molds into ovens, where they undergo a heat-cycle, turning the MR™ monomer mixture into a MR™ lens.

4. Grinding / Polishing
Grind and polish the surface of the MR™ lens to create a curvature for required strength.

5. Tinting
Tint the surface of the MR™ lens.

6. Coating
Hard Coating

Anti Reflection Coating
Coat the surface of the MR™ lens to protect from scratches, reflection etc.

7. Final Inspection
Photo_Final Inspection
Inspect the coated lens.
"MR-8 is the best in hi-index lenses"

credit: wikipedia, mitsuichem.com


  1. great! This is really helpful blog..
    thank you for sharing....

  2. Happy to know that it's OK to tint MR174. I really wonder who has ever succeeded in tinting it without the use of a tintable coating that would inevitably display huge Newton rings! Even for MR8, it's not such an easy job...

    1. Asahi-lite introduced anew type of lens called 1.74 hybrid. which can be tinted up to 80%. We are using it successively since 3 months. It is a thin layer of 1.6 material layer attached on the base side of 1.74 lens. Now it is available only in spherical.

  3. whaat is the price of mr-8 1.6????

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