Sumitomo Bakelite Co., Ltd. (President:
Tsuneo Moriya, Head office at Shinagawa ward, Tokyo) recently established their
original, proprietary new reaction technology for manufacturing an
environment-compatible type phenolic resin which is not only
environment-friendly but also light-colored after cure.
Unlike conventional
light-colored phenolic resins it has a minimized amount of unreacted residual
monomer and free from organic solvents which are legally obligated to mark as
regulated materials in such laws as the Industrial Safety & Health Law, the
Regulating Law for Toxic and Poisonous substances, the Fire Service Laws.
Moreover, it can be diluted by water to be really compatible with environmental
conditions.
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| Social Background |
Phenolic resins have superior mechanical properties,
electrical properties, heat resistance, adhesive properties, etc. and are used
traditionally for extensive applications such as thermosetting binders of
grinding wheels, friction materials, molding compounds, reinforced wood, paper
processing, laminated sheets, etc. It has such a lot of advantageous points but
on the other hand it is too dark in color when cured to make beautifully colored
products.
Attempts have been made to overcome this disadvantage in
applications which require colorfulness by additives and modification
technologies .
So far among conventional light-colored phenolic resins such
resins as modified by Bisphenol A and epoxy resins or resins composed of
additives of phosphates are popular but both types of such resins are either
high in price or do not comply with environmental requirements.
The
following Table 1. shows such conventional light-colored phenolics in
comparison:
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Table 1. Conventional light-colored phenolics
| Types of light color phenolics |
Characteristics or featured quality |
| Phenolics modified by Bisphenol
A |
Cured color is light but Bisphenol A is a suspected
endocrine disruptor and therefore a marked downward trend is
observed. |
| Phenolics modified by epoxy
resin |
Cured color is light but the resin is not
water-soluble and requires solvents listed in the Fire Service Laws as dangerous
and hazardous materials. Price is kept in a higher range. |
| Phenolics modified by melamine |
Cured color is the lightest but binding strength is
too weak. Mechanical strength after molding is low. |
| Phenolics containing
phosphates |
Cured color could be lighter with amount of additives
but with less mechanical strength and higher price. |
| Phenolics by amine catalizers |
Cured color is comparatively light but the resinis
mostly composed of solvents. Water-soluble composition is accompanied by lower
molecular weight with a lot of unreacted residual
monomer. |
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Under the above situations we have been working for
developing an environment-friendly phenolic resin of light-colored tint which
was not available by prior arts.
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| Contents of the Developed
Product |
The environment-friendly phenolic resin developed
this time was realized by establishing optimum reaction conditions by our own
proprietary technology dispensing with the use of any modifiers and additives.
The developed product is a water-soluble phenolic resin with minimized content
of unreacted phenol and formaldehyde despite the capability to be diluted with
water.
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| Distinguished features of the
technologies |
Representative properties of the newly developed
phenolic resin is shown in the following Table 2: Color samples after curing are
available on request.
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| Table 2. Representative properties of the developed
phenolic resin. |
| Property |
Conditions • unit |
Representative value |
| Appearance |
Visual |
Liquid of yellowish tint |
| Specific gravity |
At 25°C |
1.25 |
| Viscosity |
At 25°C • mPa • S |
1,500 |
| Gel time |
At 150°C • sec |
120 |
| Un-volatile matter |
At 135°C • % |
75 |
| pH |
At 25°C |
7.5 |
| Solubility in water |
At 25°C • % |
200 |
| Free phenol |
% |
5.0 max. |
| Free formaldehyde |
% |
1.0 max. |
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| * |
Light-colored tint and high mechanical
strength.
Color tint after curing is equivalent to that of conventional
phenolics modified by Bisphenol A which allows colorful coloring. The
composition is free from any ingredients which hider binding strength of
phenolic resins assuring of high mechanical strength of general purpose
phenolics.
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| * |
Solventless and water-soluble.
You can handle it
as a non-hazardous substance free from organic solvents.
You can also dilute
it with water for safer and more eco-friendly use of phenolic
resin.
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| * |
Towards less pollution and environmental
friendliness
Free from any pollutive and environmentally disruptive
substances such as Bisphenol A and liquid epoxy resins. Further, the unreacted
residual monomer content which has been inseparable from conventional
water-soluble phenolic resins is minimized as an eco-friendly material to such a
low level as far below the values to be controlled by laws like the Industrial
Safety & Health Law, the Regulating Law for Toxic and Poisonous
substances.
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| * |
Life and stability for preservation
Will not be
deteriorated for 1 month under storage condition of lower than
10°C.
Patents relating to the inventions of this eco-friendly
phenolic resin of light-colored tint were filed already by Patent offices and we
started marketing of binders for impregnation on a vast scale. Our clients in
the domestic and overseas grind wheel industry as well as in the abrasive paper
industry are ardently continuing their energetic evaluations, the result of
which we hope will further contribute to expanding demand and share of the
product.
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Thank you.
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