Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-10-07
2001-01-30
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C522S090000, C522S096000, C522S097000, C427S508000, C427S515000, C427S516000, C385S123000, C528S032000, C528S025000, C525S477000, C525S479000
Reexamination Certificate
active
06180741
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a liquid curable resin composition producing cured products with excellent surface slipperiness, and more particularly, to a liquid curable resin composition suitable for use as a coating material for optical fiber ribbon matrix, up-jacketing fiber, and the like.
DESCRIPTION OF THE BACKGROUND ART
In the production of optical fibers, a resin coating is provided for protection and reinforcement immediately after spinning a molten glass fiber. A known structure of the resin coating consists of a primary coating layer of a flexible resin which is coated on the surface of optical fibers and a secondary coating layer of a rigid resin which is provided over the primary coating layer. A so-called optical fiber ribbon is known in the art in the application of optical fibers provided with a resin coating. The optical fiber ribbon is made from several elemental optical fibers, e.g. four or eight optical fibers, by arranging these fibers in a plane and fixing them with a binder to produce a ribbon structure with a rectangular cross section. The binder for preparing the optical fiber ribbon from several optical fibers is called a ribbon matrix material. A multiple core ribbon structure consisting of several optical fiber ribbons is also known. The material for binding the optical fiber ribbons is called a bundling material.
An up-jacketing fiber with a thick coating layer provided over colored optical fiber is also known. The resin composition for producing such a thick coating layer is called an up-jacketing material.
The characteristics required for curable resins used as the coating materials for optical fibers include: a liquid at room temperature with a sufficiently low viscosity to be excellently coated; superior shelf life maintaining even composition distribution; good productivity at a high curing rate; sufficient strength and superior flexibility; very little physical change during temperature change over a wide range; superior heat resistance and superior resistance to hydrolysis; superior long term reliability with little physical change over time; superior resistance to chemicals such as acids and alkalis; low moisture and water absorption; superior light resistance; high resistance to oils; little hydrogen gas generation which adversely affects optical fiber characteristics; production of cured products with slippery surfaces.
In addition, in the manufacture of optical fiber ribbons and multiple core optical fiber ribbons it is important that the ribbons manufactured be smoothly wound and the wound ribbons be smoothly drawn out at a specific rate to smoothly manufacture optical fiber cables in the succeeding step. Conventionally, a lubricant such as silicone oil or a powder such as talc has been applied to the surface of the ribbon to provide a slippery surface, whereby smooth wind-up and draw-out operations of the optical fiber ribbons are ensured.
Another method to provide good surface slip characteristics is a method of including an additive such as silicone oil in the ribbon matrix material or the bundling material. The use of conventional additives, however, impairs the shelf life of the composition, that is, the addition of a large amount of additive causes the liquid composition to separate into two layers during storage, although the surface slip characteristics of the cured product are improved. If the amount of such an additive is too small, it is necessary to apply a powder such as talc when ribbons are produced, because the cured product does not have sufficient surface slip characteristics, even though the shelf life is excellent.
Furthermore, in a curable resin used as an up-jacketing material, a cured coating material must be easily removed in the course of fiber splicing.
The addition of silicone oil to up-jacketing materials has been known to allow the coated resin to be removed with ease. The use of conventional additives, however, impairs the shelf life of the composition, that is, the addition of a large amount of additive causes the liquid composition to separate into two layers during storage, although the cured material can be easily removed. If the amount is too small, no sufficient characteristics of cured product removal can be obtained, even though the shelf life is excellent.
SUMMARY OF THE INVENTION
An object of the present invention is therefore to provide a liquid curable resin composition having excellent shelf life, producing cured products with a slippery surface, and suitable for use as a coating material for optical fibers, especially as a ribbon matrix material or a bundling material.
Another object of the present invention is to provide a liquid curable resin composition producing cured products which can be easily removed when used as a coating material, and suitable for use as a coating material for optical fibers with low hydroscopic properties, especially as an up-jacketing material.
These objects can be obtained by the present invention by providing a liquid curable resin composition comprising: (a) a first polydimethylsiloxane comprising (i) at least two urethane bonds, (ii) an organic group unreactive to vinyl polymerization attached to at least one end of the first polydimethylsiloxane, and (iii) a (meth)acryloyl group attached to at least one end of the first polydimethylsiloxane, and (b) a second polydimethylsiloxane comprising (i) at least two urethane bonds and (ii) an unreactive organic group attached to at least one end of the second polydimethylsiloxane (other than (a)).
This liquid curable resin composition of the first invention is particularly preferred as a ribbon matrix material or a bundling material.
The above-described objects can be further obtained by the present invention by providing a liquid curable resin composition comprising: (a) a first polydimethylsiloxane comprising: (i) at least two urethane bonds, (ii) an unreactive organic group attached to at least one end of the first polydimethylsiloxane, and (iii) a (meth)acryloyl group attached to at least one end of the first polydimethylsiloxane, (b) a second polydimethylsiloxane comprising (i) at least two urethane bonds and (ii) an unreactive organic group attached to at least one end of the second polydimethylsiloxane (other than (a)), and (c) a third polysiloxane which does not contain any urethane bonds.
The liquid curable resin composition including the third polysiloxane which does not contain a urethane bond is particularly preferred as an up-jacketing material.
DETAILED DESCRIPTION OF THE INVENTION
The first polydimethylsiloxane used in the present invention has at least two urethane bonds and a (meth)acryloyl group attached to at least one end of said first polydimethylsiloxane as mentioned above. At least two urethane bonds are required for the polydimethylsiloxane compound to be mutually soluble in other components, thereby improving the shelf life of the liquid curable resin composition.
The urethane bonds can be produced by the reaction of a polyisocyanate and a reactive silicone compound having a hydroxyl group attached to at least one end of the reactive silicone compound, and a (meth)acrylate compound having a hydroxyl group attached thereto.
Given as examples of the polyisocyanate which can be used for this purpose are a diisocyanate such as 2,4-toluene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 3,3′-dimethylphenylene diisocyanate, 4,4′-biphenylene diisocyanate, 1,6-hexane diisocyanate, isophorone diisocyanate, methylenebis(4cyclohexyl)isocyanate, 2,2, 4-trimethylhexamethylene diisocyanate, bis(2-isocyanate-ethyl) fumarate, 6-isopropyl1,3-phenyl diisocyanate, 4-diphenylpropane diisocyanate, lysine diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, tetramethylxylylene diisocyanate, and 2,5(or 6)-bis(isocy
Komiya Zen
Ukachi Takashi
Yamaguchi Yoshikazu
Dawson Robert
DSM N.V.
Peng Kuo-Liang
Pillsbury Madison & Sutro
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