Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-09-12
2003-09-16
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S522000, C524S523000, C524S510000, C524S537000, C524S831000, C524S458000, C427S512000, C427S513000, C427S516000, C174S107000, C174S11900R, C174S1210AR, C106S014410, C106S014050, C252S184000
Reexamination Certificate
active
06620878
ABSTRACT:
The present invention relates to novel pourable liquid compositions comprising a water soluble or water swellable polymer. The invention also relates to methods and processes for improving water or moisture resistance and/or preventing water ingress into an article such as a cable.
Polymer compositions can be prepared in a variety of fluid forms. For instance it is common practice to prepare dispersions of water soluble or water swellable polymer particles in a water immiscible hydrocarbon liquid. Such compositions are usually prepared by reverse phase emulsion polymerisation of water soluble monomers, optionally followed by azeotropic dehydration. Such polymers can be dissolved or hydrated in water by mixing the reverse phase emulsion or dispersion with water, optionally in the presence of an activator surfactant. Such compositions could be used as flocculants for instance for dewatering or thickening aqueous suspensions.
It is also known to prepare water soluble or water swellable polymers as dispersions in aqueous liquids. In such known compositions the aqueous liquids comprise dissolved inorganic salts and/or dissolved water soluble polymers and/or dissolved surfactants. Although such fluid compositions are pourable they are generally more viscous than the above reverse phase emulsions and dispersions and furthermore would contain less dispersed phase water soluble or water swellable polymer. Such aqueous based dispersions of water soluble or water swellable polymer may be prepared by polymerisation of water soluble monomers in the presence of the said aqueous liquid comprising dissolved inorganic salts and/or dissolved water soluble polymers and or dissolved surfactants.
Alternatively is also possible to prepare such aqueous based dispersions of water soluble or water swellable polymer by dispersing finely divided particles of preformed polymer into said aqueous liquid comprising dissolved inorganic salts and/or dissolved water soluble polymers and or dissolved surfactants. Such compositions could be used as flocculants for instance for dewatering or thickening aqueous suspensions.
Solutions of an associative polymer in a mixture of water and polar solvent, such as alcohols and ethers are described in EP-A-358385. In such polymer solutions the amount of polymer in the polymer solutions would be generally below 30% and most preferably 5 to 15%, based on the total solution. The amount of polar solvent is generally between 5% and 20% of the polar solvent water mixture. The polymer solution would have a viscosity of below 30,000 cps, for example below 5,000 cps. The viscosity of such polymer solutions increase at least three fold upon further dilution with water. Such compositions would generally be suitable as viscosifying agents for aqueous based systems.
It is known to impart water resistance to various water sensitive materials such as paper or cardboard. Such compositions would generally be water insoluble polymers that form an impervious barrier to water or moisture.
Solutions of resinous materials in a hydrocarbon solvent for application to substrates such as wood to provide a water resistant barrier are well documented.
In the field of cable manufacture it is normal practice to apply water resistant or water absorbent materials in the form of powders to prevent the ingress of water.
In fibre optic cables care must be taken to prevent water from contacting the glass fibre as this could result in water being transmitted along the optical fibre and thus lead to the loss of light transmittence through large sections of cable.
When making fibre optic cables it is common to surround individual optical filaments with oil based greases or superabsorbent powders. Greases are normally injected into the preformed cable by an injection process, such that the grease fills the interstitial spaces between the optical fibres and the outer casing. A disadvantage of grease is that if the outer casing of the cable becomes ruptured the grease can actually seep from the cable which could result in the internal fibres becoming exposed to water penetrating the cable.
Other means for imparting water resistance to fibre optic cables is by the application of water absorbent powders. The powders would surround the optical fibres in the void between the optical fibres and the outer casing of the cable. Typically the water absorbent powders are coated onto tape and and wrapped around the optical fibres. The water absorbent powders have the disadvantage of not providing a complete barrier to water.
In both WO-A-9637900 and WO-A-9637901 processes are proposed for providing water resistance to optical fibres. In each reference the optical fibres are passed through a coating die from which a liquid mixture of absorbent and polymerisable material is applied and then passing the fibres through a UV emitter where the liquid coating is cured. The liquid mixture is said to contain no or very little water or volatile organic solvent in order to avoid a heating step. However the process relies upon polymerising the polymerisable material in situ, which in the absence of sufficient water or other solvent could inhibit the mobility of radicals and the polymerisable material and result in some unpolymerised material, which could impair the effectiveness in providing sufficient water resistance. On the other hand where the liquid mixture does contain sufficient water to allow mobility of polymerisable molecules and radicals the polymerisation is more likely to be complete but without a drying stage would still hold the water or solvent within the polymerised matrix. It is possible that such water or solvent could subsequently evaporate resulting in shrinkage and possible damage to the coating thus resulting impaired effectiveness in providing sufficient water resistance.
It would therefore be desirable to provide water or moisture resistance to optical fibres within a cable by a simple means of application.
Thus in a first aspect of the invention a novel composition is provided which amongst other uses may be applied to optical fibres to provide water and/or moisture resistance.
The first aspect of the invention is a pourable liquid composition comprising, water, a water soluble or water swellable organic polymer, comprising 25 to 90 mole % monomer or monomers selected from the group consisting of (meth)acrylamide, (meth)acrylic acid or salts thereof and 10 to 75 mole % monomer or monomers selected from the group consisting of C
8-30
alkyl (meth)acrylates, C
8-30
alkyl ethoxylated (meth)acrylates, C
8-30
alkyl (meth)acrylamides, C
8-30
alkyl ethoxylated (meth)acrylamides, C
8-30
alkyl (meth)allyl ethers and C
8-30
alkyl ethoxylated (meth)allyl ethers, and an water miscible organic volatile liquid, characterised in that the organic polymer is present as discrete particles of average diameter size of below 10 microns. Preferably the organic volatile liquid is selected from the group consisting of C
1-5
alcohols, C
3-5
ketones, C
2-5
esters and C
2-5
ethers,
Furthermore the pourable liquid composition is usually a stable dispersion of polymer particles. Thus the dispersed particles of polymer remain suspended and substantially free from settlement. The dispersion preferably remains stable for at least 30 days. More preferably the dispersion will have a stability of at least six months, most preferably 12 months.
The composition may contain at least 20 weight % water based on total weight of composition. Preferably the amount of water present in the composition is in the range 20 to 40 weight %, more preferably in the range 25 to 30 weight %.
The composition comprises dispersed particles of water soluble or water swellable polymers. The polymers may be formed entirely from an ethylenically unsaturated water soluble monomer or from a mixture of ethylenically unsaturated water soluble monomers. Water solubility is expressed in terms of the monomer having a solubility in deionised water at 25° C. of at least 10 weight %.
The ethylenically unsaturated water insoluble monomers are present in an amount of 10 t
Dungworth Howard Roger
Lyons Ian Russell
Ciba Speciality Chemicals Water Treatments Limited
Crichton David R.
Sastri Satya
Wu David W.
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