MXPA01005177A - Fiber coated with water blocking material - Google Patents

Abstract

The present invention relates to a fiber coated with a water blocking material that includes an essentially water free dispersion comprising a superabsorbent polymer and a dispersing medium. The fibers made according to this invention may be used, for example, as fiber reinforcing material used in the manufacture of cables, and in particular in yarns for fiber optical cables that use optical light wave guides for optical communication transmissions.

Description

FIBER COVERED WITH ON MATERIAL WATER LOCKER BACKGROUND OF THE INVENTION 1. Field of the invention The present invention relates to the use of a water blocking material in the form of a surface coating on a fiber. The substrate can be used on a fiber optic cable to prevent water from entering the cable. 2. Description of the related art Various processes are known for the treatment of substrates with water blocking materials. In particular, fibers, fibrous materials or yarns are impregnated with water-blocking materials in certain applications where water is undesirable.

For example, water blocking materials are used in fiber optic cables to prevent the ingress and propagation of water in the cable. Fiber optic cables are usually made by surrounding them with surrounding waveguides with reinforcing fibers that prevent the ref: 128369 lengthening of the cable, and those reinforcing fibers are then wrapped in plastic. If the water enters the fiber optic cable, it migrates inside the cable, usually longitudinally by capillary action, until the water makes contact with the sensitive waveguides and finally with optical network connection boxes. The waveguides are made of glass, and when they contact the water they become dull. The transmission efficiency of a signal through the waveguide drops until the waveguides can no longer transmit a signal. When that happens, the damaged portion of the cable may be buried or it may be placed near the bottom of large bodies of water, locating and replacing damaged sections of the cable can be time consuming and costly.

As a result of these problems, numerous methods have been developed to protect the optical fiber cable from water ingress. One method has been to coat the surrounding reinforcing fibers with a water blocking material in such a way that if the water could seep through the plastic shell, that water will be absorbed by the water blocking material in the reinforcing fibers to avoid the damage to the waveguides.

There are processes in which the treatment of fibers is carried out with water blocking material as an aqueous dispersion such as in EP-A-0 351 100. A disadvantage of this process is that the viscosity of these aqueous dispersions is very high.

In EP-A-0 666 243, a method is described in which the fiberglass bundles are treated with a dispersion of a water-absorbing material in an oil, wherein the water-absorbing medium is poly (sodium acrylate) ). In the same way the polyacrylic acid derivatives are described in W093 / 18223 as superabsorbent materials. In both cases, the water blocking materials are used in water-in-oil emulsions for the treatment of substrates, the absorbent materials being contained in the aqueous phase. However, these emulsions are complicated in their manufacture and require the use of emulsifying agents.

In general, conventional water blocking materials are based on cross-linked polyacrylics and / or cross-linked polyacrylates, such as water-in-oil emulsions. All these types of water blocking materials contain water and oil, and when the material is applied to a fiber or thread some water and oil must be removed. The removal of water and oil is an additional processing stage that is intensely energetic, limits productivity and is a burden on the environment.

Therefore, what is required is a water blocking agent that is effective and easy to apply to fibers.

None of the known water blocking materials, when applied to a substrate, fully meets the following four criteria defined as ideal industrial standards and related manufacturing requirements: First, the substrate coated with the super absorbent polymer must be easily processable when used in the manufacture of, for example, optical cables. This means that the substrate coated with the super absorbent reinforcement must have good frictional properties and a low tendency to generate deposits when spiraling or interlacing around a fiber optic center. It is known that the conventional super absorbent polymers used for coating substrates are prone to deposits due mostly to the high stiffness of the formed film or to its relatively large particle sizes, ie above 40 microns.

Second, the residual water present in substrates coated with conventional super absorbent polymers causes the formation of blisters, for example, during extrusion of the outer jacket of an optical cable.

Therefore, such coated substrates should be as dry as possible to avoid this problem of blistering. For example, water-in-oil emulsions of super absorbent polymers contain a substantial proportion of water (up to 1/3) which can cause blistering when extruding, above certain temperatures, substrates having large polymer loads. super absorbent and therefore detrimental to the overall quality of the cable.

Third, the substrate coated with the super absorbent polymer must withstand temperatures encountered during thermal processing, such as the aforementioned extrusion process. It is known in the art that most super absorbent polymers do not tolerate temperature cycles and therefore lose their ability to absorb water. The detriment of the chemical mechanism is generally associated with the formation of interlabeled anhydrides which do not constitute a good network of entrampe for the "entering" water.

Fourth, many of the aerial or link cables (sometimes referred to as lift cables) which connect overhead / underground cables to building networks are exposed to freezing conditions in many regions where they are used. It is therefore essential that in general the cable and the coated substrate is in particular resistant to freezing conditions. The icing in the cable structure not only affects the dimensional stability of the system cable but can also cause internal damage related to the reduced flexibility associated with a micro-bending crushing effect. Therefore, the resistance of the coated substrate in the cable is very important and therefore its dryness is absolutely essential. Unfortunately, a large number of known superabsorbent polymers not only contain water but are also not resistant to freezing conditions.

In view of the above, an object of the present invention is to provide a substrate coated with a water blocking material which meets the four criteria discussed above. Said substrate is highly processable, essentially free of water and tolerant to temperature, ie it is resistant to freezing and to temperature cycles.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a fiber coated with a water blocking material that includes an essentially water-free dispersion comprising a superabsorbent polymer and a dispersion medium. The fibers made according to the present invention can be used, for example, as a fiber reinforcement material in the manufacture of cables, and in particular in fiber optic cable wires that use optical waveguides for the transmission of communications.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fiber coated with a water blocking material that essentially includes a water-free dispersion comprising a super absorbent polymer and a dispersion medium. The water blocking material of the present invention is easily applied to fiber surfaces, has a good water blocking action, and does not impart the mechanical characteristics of the fiber. The fibers are usually used in the form of multiple filament yarns or fibrous materials such as nonwoven structures or other textiles.

As used herein, the term "essentially water-free" means that water in free form is present in the dispersion except water in bound form which occurs naturally in the super absorbent polymer or dispersion medium. Practically speaking, that water is usually present in an amount less than two percent by weight of the total weight of the dispersion.

The superabsorbent polymers useful in the invention may be partially crosslinked polyacrylic acid cross-linked (see US Pat. No. 4,654,039), an acrylic acid grafted polymer of partially neutralized cross-linked starch (US Pat. No. 4,076,663), a partially neutralized cross-linked copolymer of isobutylene and maleic anhydride (US Patent No. 4,389,513), a product of the super absorbent polymer saponification of vinyl acetate-acrylic acid copolymer (US Patent No. 4,324,748), a polymer hydrolyzate acrylamide or acrylamide copolymer (U.S. Patent No. 3,959,569), a hydrolyzate of an acrylonitrile copolymer (U.S. Patent No. 3,935,099), mixtures thereof, or copolymers thereof. The teachings of the above patents are incorporated herein by reference.

More specifically, examples of a super absorbent polymer suitable for use in the dispersion of the invention include a poly (acrylic) acid derivative, partially or fully neutralized and partially or fully crosslinked (PACA); a derivative of sodium or potassium poly (acrylamide-2-methylpropane sulfonate) partially or completely crosslinked (PAMPS); a poly (chlorotrimethylaminoethyl acrylate) derivative partially or completely crosslinked (PCTA); a partially or fully crosslinked poly (acrylamide) derivative (PAAD); its mixtures; or its copolymers.

Examples of PACA include Sanwet® IM 3900 available from Hoechst AG, Aqua Keep® available from Atochem, and Dry Tech® available from Dow Chemical.

The super absorbent chemical should be present in the coated fiber in an amount of 0.05 to 10.0 weight percent based on the total weight of the uncoated fiber. A range of 0.1 to 5.0 weight percent is preferred because below 0.1 weight percent the water blocking effect may be insufficient in certain uses and above 5.0 weight percent the yarn processing capacity may become more difficult due, for example, to the formation of deposits. While it is possible to use higher charges of the super absorbent polymer, such larger loads are not practical. If the fiber includes a sizing agent which is added before the treatment of the fiber with the dispersion of the super absorbent polymer, then the values for the percentage by weight refer to the dry weight of the untreated fiber without the sizing agent.

The super absorbent polymer has a particle size less than 100 microns, preferably less than 20 microns, and more preferably less than 5 misrons.

Super absorbent polymers having particle sizes of 100 microns or greater can be used, but have problems of bulking or aggregation. These problems can be overcome by reducing the particle size of the super absorbent polymer and dispersing the super absorbent polymer in a dispersion medium.

The typical particle size of a commercial PACA, such as Aqua Keep® SHP10, is given below: This table shows that commercial PACA includes polymer particles having a particle size much greater than that preferred for use in the present invention. Typically, such super absorbent polymers are used to coat hygienic products which require polymers having a comparatively large particle size.

Therefore, another aspect of the present invention is to modify the superabsorbent polymers such that such polymers have a particle size below 100 microns, preferably below 20 microns and more preferably below 5 microns. .

There are four general methods for obtaining a super absorbent polymer with particle size less than 100 microns.

First, super absorbent polymers, such as the commercially available polymers mentioned above, can be taken and the large undesirable particles separated by sieving. The main drawback in the use of this technique is that it has a very low and variable performance.

Therefore, the other three methods are preferred to prepare or obtain a superabsorbent polymer having an optimum particle size below 100 microns, preferably below 20 microns and more preferably below 5 microns. It is preferred that the particle size of the super absorbent polymer be equal to or less than the diameter of the fiber to be coated.

One method is the dry milling of the super absorbent polymer before dispersing the super absorbent polymer in the dispersing medium. Particle sizes as small as 5 microns can be produced using the Condux® CGS air injection mill from Condux® Maschinenbau GmbH & Co.

Another method is the wet milling of the super absorbent polymer made at high intensity, that is, the milling that takes place at speeds higher than 12,000 RPM, such as with the use of the Megatron® MT 5000 micronizer from Kinematica AG, after which the super absorbent polymer has been dispersed in the dispersion medium.

Yet another method is to make the super absorbent polymer with a particle size smaller than 100 microns during the polymerization of super absorbent polymer from its monomeric ingredients. In this process, the super absorbent polymer is prepared by providing a monomer of the superabsorbent polymers described above, partially or totally neutralizing the monomer, adding a catalyst and a cross-linking agent, raising the temperature of the monomer to initiate the polymerization of the monomer, maintaining the temperature during the polymerization, and evaporating the water to produce a polymer powder, all while providing a cutting speed of at least 10,000 revolutions per minute during the entire process to produce a polymer having a particle size below of 100 microns.

In another embodiment, prior to the polymerization step, the mixture of the fully or partially neutralized monomer, the cross-linking agent and the catalyst can be added to the reactor containing a hydrocarbon solvent to prepare a reverse suspension polymerization. The solvent hydrocarbon should be present in an amount of 2 to 3 times the weight of the monomer, the cross-linking agent and the catalyst. The solvent hydrocarbon may be a C6, C7 or C8 alkane or an aromatic material. A preferred aromatic solvent is toluene. In the evaporation stage, the solvent as well as the water must be removed.

In a preferred embodiment, a super wetting agent (S A) may be added during the polymerization step by combining the SWA in the solvent in an amount of 0.05 to 10%, preferably 0.5% based solely on the weight of the solvent and the SWA. The SWA and the solvent are added to the monomer solution, preferably in a weight ratio of SWA to solvent in the aqueous monomer solution of 1: 1 to 3: 1. The solvent and water are removed by distillation at the end of the polymerization. The distillation temperature is adjusted depending on the solvent used, depending on whether there is vacuum availability and whether an azeotropic distillation can be performed. Typically a water-cyclohexane mixture can be separated from 80 to 90 ° C under vacuum. It is also possible to add the SWA without solvent directly in the monomeric solution since the surfactant effect of the SWA is also observed in the aqueous medium.

As used herein, the term "SWA" means a super wetting agent having a surface tension below 30 milliNewtons per meter (mN / m). Preferably, the SWA has a surface tension below 25 mN / m. Such SWA are described, for example, in the Polymeric Encyclopedia, Volume 10, Silicone Polymers, CRC Press 1996. This surface tension is lower than that of the usual oil-based surfactants. organic substances that are in the range of 30 to 35 mN / m. Examples of SWA include: 1. trimethylsilane; 2. a polyethylene oxide modified trimethylsilane (PEO), ie a trimethylsilane branched with a polyether containing ethylene oxide propylene oxide (OE / OP) sequences, such as Tegopren® 5840 supplied by Th. Goldschmidt AG; 3. trisiloxane; 4. a trisiloxane modified with polyethylene oxide (PEO), that is, a branched trisiloxane with a polyether containing ethylene oxide propylene oxide (OE / OP) sequences, such as Tegopren® 5878 available from Th.

Goldschmidt AG; . polydimethylsiloxane (PDMS); 6. a polydimethylsiloxane modified with polyethylene oxide (PEO), that is, a polydimethylsiloxane branched with a polyether containing ethylene oxide propylene oxide (OE / OP) sequences, such as Tegopren® 7008 available from Th. Goldschmidt AG; 7. a polyether-modified siloxane such as Tegopren® 5845 available from Th. Goldschmidt AG.

The advantage of using a SWA in the polymerization is that a super absorbent polymer having a relatively smaller particle size is obtained, ie, a super absorbent polymer having a particle size below 5 microns, with a high percentage of particles below 1 micron. The smaller the size of the super absorbent polymer particle, the faster that polymer will absorb water, and the lower the polymer charge in the fiber needs to be due to the improved distribution of the smaller particles within the fiber.

The dispersing medium may be an oil a super wetting agent, a combination of an oil and a super wetting agent, a finished oil composition, glycol, or mixtures thereof.

Oils that can be used in a super absorbent polymer - oil dispersion include mineral oils, vegetable oils, and fully synthetic oils. Such oils should have a low viscosity, ie a kinematic viscosity of 50 to 350 mm2 / s at 20 ° C, preferably 80 to 200 mm2 / s at 20 ° C. In addition, such oils should be thermally resistant, that is, with losses of less than 5 percent by weight when exposed to heating at 230 ° C for 2 hours.

Examples of oils that may be used are those described in US 5,139,873 and US 5,270,113. For example, US 5,270,113 discloses a finished oil composition which includes 30-70% by weight of a stearic lubricant composed of an alcohol and a carboxylic acid, of 20-50% by weight of an emulsifier system composed of unsaturated ethoxylated fatty acids or ethoxylated alcohols or alkylamines, 5-15% of an antistatic agent, 0.2-2% of a corrosion inhibitor, and optionally other additives. In order that the oil has the heat resistance described above, it is preferred that the sterols be an aromatic derivative and that the antistatic agent include a derivative of a sulfonate and / or a phosphate. These oils may also include hydrophobic active ingredients such as ketene dimers as described in US 5,275,625.

For oils that include an emulsifier system, the emulsifier system can be replaced by an SWA as described above. In that case, the SWA, which does not include any solvent or water, is present in an amount of 0.05 to 50 weight percent of the oil composition.

These oils advantageously contribute to the water-blocking action of the super absorbent polymer by allowing water to diffuse more easily between and by the super absorbent polymer particles. Other advantages of these oils are that they improve the processing capacity of the coated fiber and provide antistatic protection to the fiber.

If the dispersing medium is an oil that does not yet include a SWA, then the oil dispersing medium may include SWA. The SWA can be any of those described above, and is typically used in amounts of 0.05 to 95%, preferably 10 to 50%, more preferably 30 percent by weight based solely on the total weight of the SWA and the oil.

The SWA in a dispersing medium containing SWA provides certain advantages to the water blocking material of the present invention. The SWA improves the hydrophilic-lipophilic balance of the super absorbent polymer, dispersing the medium and the fiber to obtain a more homogeneous and rapid dynamic wetting of the fiber surface which results in a homogeneous coating that allows a lower load of the super polymer. absorbent to obtain a desired water blocking effect. In addition, this homogeneity and dynamic wetting faster allows the online application of the water blocking material in the fiber.

Alternatively, the dispersing medium can also be only a water-free SWA.

If the dispersing medium includes glycol, the glycol can be ethylene glycol or propylene glycol or any other glycol derivative. In addition, the glycol may include an ethylene propylene emulsifying agent. Glycol can advantageously contribute to the protection of the optical cable against freezing.

The dispersing medium may also include other antifreeze compositions such as dimethyl sulfoxide, potassium or sodium salts, or mixtures thereof. The amount of antifreeze composition can be easily evaluated knowing that 1.5 grams of glycol are required to lower the freezing point of 1 gram of water at -40 ° C.

After the dispersion of the super absorbent polymer is applied to the fiber, the dispersing medium remains in the fiber. As stated above, the inventive water blocking material is essentially free of water, which makes the material easier to apply and easier to use than water-in-oil-based water blocking materials that require water and The oil is removed as a step in the application of acrylic water blocking material to the fiber.

As used herein, the term "fiber" includes fibers composed of organic and inorganic materials. Natural fibers and synthetic fibers can be used as organic fibers. Examples of natural organic fibers are cellulose fibers, wool fibers, silk fibers. Examples of synthetic fibers are rayon fibers, regenerated cellulose fibers, aliphatic and aromatic polyamides, polyesters, polyolefins, polyacrylonitriles, polyvinyl chlorides, polyvinyl alcohols, and the like. Examples of inorganic fibers are glass fibers, carbon fibers, metal fibers, ceramic fibers, mineral fibers, boron fibers and the like. Preferred fibers include glass fibers, aramid fibers, nylon fibers, polyester fibers, such as poly (ethylene terephthalate) fibers and polymethacrylates, and cellulose fibers including those of regenerated cellulose.

Before being coated with the dispersion, it is preferred to dry the fiber in such a way that it is completely dry to protect it against blistering during the extrusion of the outer jacket of the cable and to protect it against freezing when the cable is exposed to low temperatures. For the same reason, it is preferred that the super absorbent polymer be completely dry before dispersing in the dispersing medium.

For use in fiber optic cables, the fibers should have a specific fracture strength of 2.65 to 33.5 cN / dtex (3 to 38 g / den) and a specific modulus of 8.83 to 2297 cN / dtex (10 to 2500 g) / den).

Aramid fibers are polymer fibers that are partially, predominantly or exclusively composed of aromatic rings, which are connected by means of carbamide bridges or optionally, also also by means of other bridging structures. The structure of such aramides can be elucidated by the following general formula of repetitive units: (-NH-A1-NH-C0-A2-C0) n wherein Al and A2 are the same or are different and mean aromatic and / or polyaromatic and / or heteroaromatic rings, which may also be substituted. Typically Al and A2 can be independently selected from each other, 4-phenylene, 1,3-phenylene, 1,2-phenylene, 4,4'-biphenylene, 2,6-naphthylene, 1,5-naphthylene, 1,4-naphthylene, phenoxyphenyl-4,4 '-diylene , phenoxyphenyl-3,4'-diylene, 2,5-pyridylene and 2,6-quinolylene which may or may not be substituted by one or more substituents which may comprise halogen, C1-C4 alkyl, phenyl, carboalkoxy, C1-6 alkoxy C4, acyloxy, nitro, dioalkylamino, thioalkyl, carboxyl and sulfonyl. The group -CONH- can also be replaced by a carbonyl hydrazide group (-CONHNH-), azo group or azoxy group.

Additional useful polyamides are described in US Pat. No. 4,670,343 wherein the aramid is a copolyamide in which preferably at least 80% mol of the total of Al and A2 are 1,4-phenylene and phenoxyphenyl-3,4'-di-ethylene which it may or may not be substituted and the content of phenoxyphenyl-3,4 '-diylene is from 10% to 40% mol.

Fibers derived from fully aromatic polyamides are preferred.

Examples of aramides are poly-m-phenylene isophthalamide and poly-p-phenylene isophthalamide.

Additional suitable aromatic polyamides have the following structure (-NH-Arl-X-Ar 2 -NH-CO-Arl-X-Ar 2 -CO-) n where X represents 0, S, S02, NR, N2, CR2, CO.

R represents H, C 1 -C 4 alkyl and Arl and Ar 2 which may be the same or different are selected from 1,2-phenylene, 1,3-phenylene and 1,4-phenylene and which at least one hydrogen atom may be substituted with halogen and / or C1-C4 alkyl.

The additives can be used with the aramid, in fact it has been found that other polymeric materials can be combined with the aramid as much as up to 10% by weight or that the copolymers can be used having as much as 10% of another diamine substituted by the diamine of aramid or as much as 10% of another diacid chloride substituted by the diacid chloride of aramid.

It is also possible to use fibers comprising blends of the above materials including hybrid fibers. In addition, two-component fibers according to the invention, whose centers consist of a material different from the skin, can also be used.

The fibers of the invention can be round, flat or they can have a cross section of another shape, or they can be hollow fibers. In addition, the term "fiber" includes endless fibers (filaments) and short fibrous structures, microfibers and multifilaments. In addition, the fibers can be made into threads of short fibrous structures, which are spun, as well as yarns of endless fibers. The fibers can be used to make fibrous materials in woven or non-woven form such as the inclusion of wool, lint, and felt.

The fibers coated with water blocking material of the present invention possess an excellent water blocking effect because the superabsorbent polymer applied to the fiber swells on contact with water and thus prevents the penetration of more water between the fibers. The mechanical characteristics of the fiber are not deteriorated by the super absorbent polymer deposited in it. Since a water blocking action is already achieved with small amounts of the super absorbent polymer on the surface of the fiber, the weight and volume of the fiber does not substantially increase such that the fibers can be used in the same applications as with the fibers not coated with similar processing characteristics.

The fibers made according to the invention can be used, for example, as a fiber reinforcement material used in the manufacture of cables, and in particular fiber optic cables that use optical waveguides for optical communication transmissions. In fiber optic cables, multiple filaments of glass, aramid or other resistant elements are used as tension release fibers or as reinforcing fibers. However, the fibers of the invention are not limited to these uses and can be used in any application where it is desired to absorb water in order to prevent the propagation of water.

The dispersion of the super absorbent polymer in the dispersing medium contains from 0.1 to 70% by weight of the super absorbent polymer, preferably from 20 to 40%, based solely on the total weight of the dispersing medium and the super absorbent polymer. If the dispersing medium includes a SWA, then relatively small amounts of the super absorbent polymer are needed to obtain a desired water blocking effect. Higher loads of the super absorbent polymer can be used, but it becomes impractical because the stability of the dispersion decreases. The amount of the super absorbent polymer used in the dispersion to coat the fiber is selected from the aforementioned range based on the viscosity of the dispersing medium such that a uniform coating of the dispersion is provided on the surface of the fiber. This is especially important when the fiber is in the form of yarns, multiple filaments or fibrous material, because when the water blocking material is applied to these materials it is desired to obtain the best penetration within the yarn or bundles of yarns in order to coat as many fibers as possible.

The dispersion can be done by adding the super absorbent polymer in powder form into the dispersing medium while stirring the dispersing medium at a rate that ensures a uniform distribution of the super absorbent polymer within the dispersing medium. If an impregnation bath is used to coat the fiber by passing the fiber through the bath, then the dispersion is continuously maintained in motion, for example by agitation.

The size of the fibers for many of the applications, such as for use in fiber optic cables, is in the range of 10 to 15 microns, and therefore the super absorbent polymer particles should have a particle size below 100 microns, preferably below 20 microns, and more preferably below 5 microns.

The dispersion can be applied to the fiber by any conventional coating process, for example, roller coating with or without a doctor knife, spray coating, dip coating, coil system, or using a finely tuned application (eg. dosage), or using any other coating device. If desired, the dispersion can be applied in a multi-step process in which the fiber is coated several times with the dispersion. Ultrasonic systems can also be used in order to improve the uniformity or penetration of the dispersion. With the fibers, it is preferred to use a dip coating method in which the oil dispersion is present in an impregnation bath and the fibers to be treated pass through the bath. However, at higher coating speeds, a dosing applicator will be preferred. With fibrous materials in two-dimensional form, other processes such as spray coating as well as dip coating can be used.

The coating speed can be adjusted between 0.1 and 1200 m / min depending on the selected process. A process in which the dispersing medium, such as oil, is not removed, has the additional advantage of significantly increasing coating speed, and therefore productivity, since the fiber can be coated at high speeds without being limited by the residence time required to evaporate the dispersing medium. The typical speeds are 60 m / min for a different fiber treatment than during the spinning process, and 800 m / min for the coating speeds during the manufacture of the fiber.

It is known that polymer fibers absorb moisture. It is therefore preferred to precondition the fiber in order to feed a completely dry fiber to the coating process. This can be easily achieved by conventional fiber drying techniques, or advantageously during spinning of the fiber.

The temperature of the dispersion can be selected in order to improve fiber penetration and uniformity of coverage and is only limited by the temperature resistance of the components of the dispersion. However, a range of 10 to 100 ° C is preferred, a range of 35 to 75 ° C being more preferred.

The invention will be explained in more detail with reference to the following examples: EXAMPLES EXAMPLE 1 This example is directed to a method for the production of a super absorbent polymer which has a particle size below 100 microns from a monomer.

A Megatron® MT5000 reactor was mounted with a device for introducing solids as well as liquids, said reactor having a high-intensity micronising cell rotating at 16,000 RPM, a system for purging with inert gas, a series of temperature sockets and a heating and cooling consisting of a jacket in which a heat transfer fluid circulates at a precise pretended temperature. This reactor was used to polymerize a monomer to obtain a super absorbent polymer with a particle size below 100 microns.

The micronizer was set at a rotational speed of 16,000 RPM, and a given amount of an aqueous solution containing about 80% by weight acrylic acid stabilized with hydroquinone was quantitatively neutralized with a 20% sodium hydroxide solution. This was done in a manner in which the temperature in the micronizer did not exceed 35 ° C.

Once the temperature was stabilized, 2.8% by weight was added to the reactor with respect to the amount of acrylic acid, of an aqueous solution of 2% sodium persulfate. The sodium persulfate solution acted as a catalyst in the polymerization. This solution can be replaced by any similar catalyst known in the art for use in related reactions. While the temperature was carefully maintained at 30 ° C, 0.5% by weight of ethylene glycol diglycidyl ether was added to the reactor, with respect to the amount of acrylic acid. Ethylene glycol diglycidyl ether acted as a cross-linking agent in the polymerization of acrylic acid, but can be substituted by any other cross-linking agent known in the art to be at least one bifunctional covalent cross-linking agent or ionic cross-linking agents such as aluminum sodium sulfate. The temperature was raised to 40 ° C and maintained for a 15 minute stabilization period while purging nitrogen through the reactor.

After a period of 15 minutes the temperature of the liquid in the reactor was raised to 70 ° C to allow the polymerization to begin. The contents of the reactor were carefully maintained at this temperature for approximately 30 minutes which are sufficient to obtain a quantitative polymerization of the neutralized acrylic acid. The speed of the rotary micronizer of 16000 RPM was maintained throughout the polymerization.

Subsequently the temperature was raised to 125 ° C to remove the aqueous phase by evaporation. This separation can also be done by mechanical means such as ultrafiltration or centrifugation. After the evaporation of the water was completed, a super absorbent polymer was obtained in the form of very fine particles with well-distributed sizes below 20 microns.

After appropriate purification the super absorbent polymer powder can be used to prepare the dispersion of the invention. The process described herein can be easily adapted to polymerize particles of other super absorbent polymers of the invention for sizes below 100 microns. The typical particle size distribution was as follows: 50% of the particles were below 8 microns; 10% of the particles were below 3 microns; 90% of the particles were below 12 microns.

The particle size was measured using a Mastersizer® Micron from Malvern Instruments Ltd., United Kingdom, suitable for the analysis of the particle size range from 0.3 to 300 microns in both dry and wet media.

EXAMPLE 2 A para-aramid fiber-free finishing yarn (Kevlar® type 49, 1580 dtex), comprising poly-para-phenylene diamino-terephthalamide was treated with a dispersion of 35% (by weight) super absorbent polymer prepared in accordance with Example 1 in a finished oil as described in US 5,270,113 which included 30-70% by weight of a stearic lubricant composed of an alcohol and carboxylic acid, 20-50% by weight of an emulsifier system composed of unsaturated ethoxylated fatty acids or ethoxylated alcohols or alkylamines, 5-15% of an antistatic agent, and 0.2-2.0% of a corrosion inhibitor. The main component of the finished oil was a stearic lubricant synthesized from an alcohol and a carboxylic acid, and had suitable hydrophilic properties to allow a rapid propagation of water between the super absorbent polymer particles thereby improving the water blocking effect of the super absorbent polymer. The yarn was coated with a dispersion that produced a coating of the yarn which had an amount of 2.5% super absorbent polymer and 4.5% oil, based on the dry weight of the uncoated yarn.

The para-aramid yarn obtained in this manner, coated with the aforementioned dispersion, was tested to determine its water blocking property in the column test described below.

PROCEDURE OF THE PROOF OF THE COLUMN: The water blocking action of the yarn of this Example was determined using the through flow test. In this test the internal cylindrical space of a section of glass tube opened at both ends was filled with a set of wires, in such a way that the longitudinal axis of the set of wires was substantially parallel with respect to the longitudinal axis of the cylindrical space in the which was placed the whole. The tube filled with the threads was cut completely in a direction perpendicular to its longitudinal axis in two parts, so that a cylindrical test tube of a length of 50 mm was formed in such a way that the ends of the assembly of yarns present in the test tube obtained in this manner coincided approximately with the ends of the test tube. Next, one end of the test tube was connected to the contents of a water container and subjected to the pressure of a water head of a particular height. The time required to wet the entire set of wires in the tube is referred to as the through flow time. This time is a measure of the water blocking action of the yarn. The flow-through time was taken as the time that passes after the application of water pressure to one end of the test tube and before the first drop appears at the other (free) end.

The flow-through test was carried out under the following conditions: The number of wires in the test tube was selected such that the assembly formed therefrom can completely fill the internal cylindrical space of the test tube. For the linear density of a dtex yarn of 1580 it was found that this number was 100, giving a total linear density of the dtex yarn set of 158,000. A coated wire according to this Example passed the column test. The effective water blocking activity remained fixed after 3 weeks when the test ended.

EXAMPLES 3-5 The Aqua Keep® SHP10 polymer was milled twice dry in a Condux® CGS air injection mill from Condux® Maschinenbau GmbH & Co., and the polymer had the following particle size: 50% of the particles were below 9 microns; 10% of the particles were below 4 microns; 90% of the particles were below 15 microns.

This ground polymer was used to make dispersions as in Example 2 with varying amounts of super absorbent polymer and the finished oil of Example 2. The 1580 dtex yarns were coated according to Example 2 with the following fillers. %? that Oil% SAP weight * time in test column Example 3 2.3 1.2 > 3 weeks Example 4 2.6 1.4 > 3 weeks Example 5 4.5 2.5 > 3 weeks * = Super absorbent polymer As indicated above, the threads of each of Examples 3, 4 and 5 passed the column test and the effective water blocking activity remained fixed after three weeks when the test ended.

EXAMPLES 6-8 A dispersion was made as in Example 2 using the Aqua Keep® SHP10 polymer (unground) and the finished oil of that Example. The dispersion was wet-milled for 30 minutes at 12,000 RPM using the Megatron® MT 5000 micronizer from Kinematica AG. The temperature in the micronizer was maintained at 15 ° C.

The polymer in the dispersion had the following particle size: 50% of the particles were below 12 microns; 10% of the particles were below 5 microns; 90% of the particles were below 19.5 microns.

The yarns were coated as in Example 2 using dispersions with varying amounts of super absorbent polymer and finished oil as indicated below: % weight Oil -% weight SAP * time in test column Example 6 2.3 1.2 > 3 weeks Example 7 2.6 1.4 > 3 weeks Example 8 4.5 2.5 > 3 weeks Super absorbent polymer As indicated above, the strands of each of Examples 6, 7 and 8 passed the column test and the effective water blocking activity remained fixed after three weeks at the end of the test.

COMPARATIVE EXAMPLE 9 A Kevlar® 49 free-finish yarn, 180 dtex, was treated as in Example 2 with about 1 weight percent of finished oil without the super absorbent polymer. The finished oil was the same as that used in Example 2. The water blocking behavior of the yarn was measured in a device for testing the column as in Example 2, using the same amount of yarn, and after 2 minutes the thread did not block the water but let it run through the column.

COMPARATIVE EXAMPLE 10 A Kevlar® 49 free finish yarn was treated as in Example 9 except that the yarn was coated with about 5 weight percent finished oil. The water blocking behavior of the yarn was measured in a column test device as in Example 2, using the same amount of yarn, and after 2 minutes the yarn did not block the water but let it run through. of the column.

EXAMPLE 11 A super absorbent polymer was made as in the Example 1, except that a solution of super wetting agent (SWA) -solvent was added to the monomer solution before starting the polymerization keeping the micronising cell rotating at a speed of 16000 RPM.

A SWA-solvent solution was prepared by adding 0.5 weight percent of the silicone wetting agent Tegopren® 5845 to 99.5 weight percent cydohexane. The dissolved oxygen had been removed from the cyclohexane before being added to the SWA using a nitrogen purge.

The polymerization of the monomer was carried out as in Example 1, and subsequently the cyclohexane and water were removed from the polymer by vacuum distillation at 80-90 ° C. The particle size distribution of the polymer was as follows: % of the particles were below 0.3 microns; 50% of the particles were below 0.8 microns; and 90% of the particles were below 3 microns.

The particle size was measured using a Mastersizer® Micron from Malvern Instruments Ltd. U.K. suitable for the analysis of particle size in the range of 0.3 to 300 microns in both dry and wet environments.

EXAMPLE 12 A finishing yarn free of para-aramid fibers (Kevlar® type 49, 1580 dtex-) completely dry was treated as in Example 2 except that the super absorbent polymer used was the preparation according to Example 11. A coated yarn according to this example passed the test of the column. The water blocking activity remained fixed after three weeks when the test ended.

EXAMPLES 13-14 Threads were treated with a super absorbent polymer as follows. A super absorbent polymer was prepared according to Examples 3-5. The ground super absorbent polymer was added to the dispersing medium of a water-free finished oil as in Example 2 and a super wetting agent of Tegopren® 5845 in varying amounts. In Examples 13 and 14, the proportion of the components was 30 percent by weight of super absorbent polymer, 50 percent by weight of water-free finished oil, and 20 percent by weight of Tegopren® 5845.

The yarns were coated according to Example 2 with the charges indicated below. % weight Oil% weight SAP time in test column Example 13 1.2 0.6 > 3 weeks Example 14 2.4 1.2 > 3 weeks As indicated above, the threads of Examples 13 and 14 passed the column test and the water blocking activity remained fixed after three weeks at the end of the test.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (20)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property.

1. A fiber coated with a water blocking material, characterized in that it includes a dispersion comprising a super absorbent polymer and a liquid dispersing medium and contains less than two weight percent water.

2. The fiber according to claim 1, characterized in that the super absorbent polymer in a poly (acrylic acid) derivative partially or fully neutralized, partially or completely crosslinked; a derivative of the poly (acrylamide-2-methyl-propane-sulphonate of sodium or potassium) partially or completely with. cross links; a poly (chloro-trimethylaminoethyl acrylate) derivative partially or fully crosslinked; a derivative of the poly (acrylamide) partially or fully cross-linked; its mixtures; or its copolymers.

The fiber according to claim 1, characterized in that the super absorbent polymer is present in an amount of 0.05 to 10 weight percent based on the weight of the uncoated fiber.

The fiber according to claim 1, characterized in that the super absorbent polymer is present in an amount of 0.1 to 5 weight percent based on the weight of the uncoated fiber.

The fiber according to claim 1, characterized in that the super absorbent polymer is in the form of particles having a particle size below 100 microns.

6. The fiber in accordance with the claim 1, characterized in that the super absorbent polymer is in the form of particles having a particle size below 20 microns.

The fiber according to claim 1, characterized in that the super absorbent polymer is in the form of particles having a particle size below 5 microns.

The fiber according to claim 1, characterized in that the dispersing medium is an oil, a super wetting agent, a combination of an oil and a super wetting agent, a finished oil composition, a glycol, or mixtures thereof.

The fiber according to claim 8, characterized in that the super wetting agent has a surface tension below 30 microns per meter.

10. The fiber according to claim 8, characterized in that the super wetting agent is selected from the group consisting of trimethylsilane, a trimethylsilane modified with polyethylene oxide, trisiloxane, a trisiloxane modified with polyethylene oxide, polydimethylsiloxane, a polydimethylsiloxane modified with polyethylene oxide, polyethylene, and a siloxane modified with polyether.

The fiber according to claim 1, characterized in that the fiber is a glass fiber, an aramid fiber, or mixtures thereof.

The fiber according to claim 1, characterized in that the fiber includes poly (p-phenylene terephthalamide).

13. A yarn, characterized in that it comprises numerous fibers according to claim 1.

14. A fibrous material, characterized in that it comprises numerous fibers according to claim 1.

15. An optical fiber cable, characterized in that it comprises waveguides of fiberglass, said guides surrounded by yarn comprising a fiber according to claim 1.

16. A method for coating a fiber with a water blocking material, characterized in that it comprises the steps of provision of a fiber and application to the fiber surface of a dispersion comprising a super absorbent polymer and a liquid dispersing medium and containing less than two percent by weight of water.

17. The method according to claim 16, characterized in that it additionally comprises the application of the dispersion of a superabsorbent polymer in a dispersant medium on the surface of the fiber in such a way that the amount of superabsorbent polymer in the fiber is 0.05 to 10 percent by weight based on the weight of the uncoated fiber.

18. The method according to claim 16, characterized in that it comprises the provision of a dispersion which includes 0.5 to 70 weight percent of a super absorbent polymer.

The method according to claim 16, characterized in that it additionally comprises the provision of a dispersion wherein the super absorbent polymer is in the form of particles having a particle size of less than 100 microns.

20. The use of a dispersion, characterized in that it comprises a super absorbent polymer and a liquid dispersing medium and containing less than two weight percent water to coat a fiber.