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Manufacturing the Products the Market is Highly Demanding

Our "Ultra-Soft Dumping Rubber" and "EPT Natural Compound" are highly regarded in the market for the superior technology in making.

Ultra-Soft Dumping Rubber - Low Hardness Isobutylene-Isoprene Rubber

Isobutylene Isoprene Rubber (IIR) is weather, chemical, ozone, heat resistant, and electrically insulating, also having low permeability of gaseous body.
Because of its low resilience character along with fast periodic damping absorption nature, it is widely adopted in various vibration isolating and shock absorbing materials.
Generally, the limitation of the softness of IIR, in JIS (Japan Industrial Standard) Hardness Class A, is around 15 degree Celsius. Recently with integration of semiconductors, more electronics products require "softer" absorbent. At K3, our Ultra-Soft Dumping Rubber has JIS Class A hardness of 0~10 degree Celsius.
In the past, compounding with less than 10 degree Celsius hardness was a quite difficult process. Our product can withstand the vibration of electronics of low frequency range whilst being water and dust proof.


  • Low Hardness (less than 10 degree Celsius) - Our special Kneading technique realized hardness of 0~10 degree Celsius
  • Vibration Free,Shock Absorbing - High dumping with low resilient, absorbing striking energy.
  • High Seal Ability - High adhesion, high on water and dust proofing
  • Many Color Variation - Various color is available upon request

[Use Sample]

  • Shock absorbent on electronic equipment, precision machine, measurer
  • Damping materials for low frequency range vibration
  • Cushion insole of shoes
  • Water and dust proof packing on watch, camera and other precision instruments
  • Water proof packing and gasket
  • Airtight packing and gasket

EPT Natural Compound "KW Series"

KW Series is our unique EPT Natural Compound. You may use it as is or colored upon request. In order to meet the small volume order, the package is all in 30kg unit. Various hardness grades of 40,50,60,70,80 degree Celsius are available. It may also be customized upon your request.

[Physical Properties of KW Series]

 UnitTest MethodNatural Compound KW Series
Master Batchg  1000
Accelerant TL-PTg  2.2
TRAg  2.2
Mg  4.1
Actor Rg  2.8
Sulfurg  1.4
[Physical Property of Unvulcanized Rubber]
Mooney Viscosity K6300100 degree Celsius3027243044
Mooney Scorch K6300      
Minimum Viscosity Vm  121 degree Celsius2219162129
Period t5minute 121 degree Celsius29.326.320.318.516
Vulcanization t90minuteCurelastometer170 degree Celsius10.910.89.911.311
Physical Property of Vulcanized Rubber
(General Physical Property: 170 degree Celsius x 10min. Press Vulcanization, CS:170 degree Celsius x 15min. Vulcanization)
300% Tensile Stresskg/cm2K6251 2023404573
Tensile Strengthkg/cm2 130140140145150
Elongation% 900830660640560
Permanent Compression Disformation%K626270 degree Celsius x 22h4338333438
Permanent Compression Disformation%100 degree Celsius x 22h6361606060
Heat Aging Resistance (70 degree Celsius Heat Aging Resistance)
Tensile Strength Variation Rate%K625170 degree Celsius x 70h107367
Elongation Variation Rate% -1-11-7-14-10
Hardness VariationdegreeK6253Atype34421
Heat Aging Resistance (100 degree Celsius Heat Aging Resistance)
Tensile Strength Variation Rate%K6251100 degree Celsius x 70h104943
Elongation Variation Rate% -18-21-18-25-23
Hardness Variation RatedegreeK6253Atype46642