FI89604B - Mixture material which expands through the action of moisture, the production and composition thereof, and mode of application - Google Patents

Description

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Moisture-expandable alloy material, its manufacture and composition, and its uses

Blandningsmaterial som vidgar ut sig genom inverkan av fuktighet, dess framställning och sammansättning samt användningssätt 5 10

The present invention is directed to an alloy material that tends to swell without significant dissolution in water or aqueous solutions.

More specifically, the invention relates primarily to a composite material forming a coating layer on at least one surface of a solid and uniform support substrate containing a high blend polymer powder that tends to swell in water or aqueous solutions, to a method of making this blend material, to a method of making the method, and

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Alloy materials are already known in the past, which tend to swell in water without more significant dissolution. Such materials are commonly used in the electrical cable manufacturing industry. They are then used in the form of a strip to coat the cables to ensure their longitudinal tightness, and they form a plug when swollen when water accidentally penetrates the cable, plug 1 *. extending up to the level of the breaking point of the sheath and thus preventing water from spreading inside the cable.

30 These types of tape include the tape marketed by Freundenberg, Weinheim, Federal Republic of Germany, under the trade name VILEDON-FIBREX, with known references K3310, K3312, K3313 and 3303C, and the tape marketed by Firet, Veenendaal, The Netherlands, with known references 3C, 3C 115 3E 113, 3E 114, 3E 115 and 3E 116 in FR 81 02863.

These strips mainly comprise a polymer powder which expands under the action of moisture placed between the two layers of nonwovens.

2 89604 The cohesion of this powder mixture is achieved by mixing a thermoplastic material (in powder, fiber or other form) with an expandable polymer powder. By the combined action of compression and heat, the thermoplastic material softens and becomes adhesive-like, thus ensuring the cohesion of the mixture. However, this bonding of the thermoplastic material has one side effect: the partial clogging of the polymer powder, which expands under the influence of moisture, thus limiting its ability to expand under the influence of moisture.

According to the present invention, it has been possible to considerably improve the properties of such an alloy material by simplifying its structure, i.e. by replacing the thermoplastic substance contained in the previous alloys with a water-soluble binder. The invention relates, inter alia, to an alloy material obtained in this way.

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The main object of the invention is a composite material forming a coating layer on at least one surface of a solid and flat support, which contains a moisture-expandable polymer powder attached to the support by means of a water-soluble binder, characterized in that the coating comprises mainly: 95-55% by weight moisture-expandable polymer powder; : 25 to 5-23% by weight of a water-soluble binder; and 0-22% by weight of surfactant.

Such material can be used where water enters. 30 to penetrate and also has many alternative uses.

It can thus be used as a sealing tape in cables, mainly electric cables, but also in agriculture to promote germination or to plant seedlings: 35 or as a "drying fungus" in medicine or surgery.

3 89604 The support for this material is mainly selected according to the intended use.

Suitable substrate materials are mainly non-woven, fabric, 5 paper or plastic. In most applications, especially in the industry of power transmission cables, telecommunications equipment or optical fibers, it is preferably flexible.

If desired, the coating layer can be coated with a water-permeable film 10, in particular a non-woven coating. However, at least for most embodiments, such a protective film is not required and only complicates the manufacture of the alloy material and increases the cost without providing any particular advantage.

The moisture-expandable polymer may contain only one polymer or a mixture of different polymers compatible with the support of the application in question, being able to swell considerably under the influence of water or aqueous solutions by "storing" them without being completely soluble in water, i. that its solubility in these liquids is less than 5%.

It is recommended that the moisture-expandable polymer be selected to be able to absorb water at least 15 times its own weight.

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The moisture-expandable polymer is preferably selected for the formation of modified acrylic polymers, refined starches, polyacrylamides, carboxymethylcellulose and its derivatives, and most preferably generally "superabsorbent", i.e., at least 15 times its own weight of water or aqueous solution.

As such superabsorbent polymers, there may be mentioned, by way of non-limiting example: 4 89604 acrylic polymer product marketed by JAPAN CATALYTIC CHEMICAL under the name AQUALIC; An acrylamide polymer marketed by CYANAMID under the brand name HYD-5 ROBLOCK; A carboxymethylcellulose polymer marketed by HERCULES under the tradename AQUASORB; 10 - Starch / acid-polyacrylic polymer obtained by processing marketed by LION under the trade name LION-POLYMER; and a sodium polyacrylate polymer marketed by GRAIN PROCESSING under the tradename WATER-LOCK J.

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The water-soluble binder is selected from the list of water-soluble binders capable of adhering to the selected support of the selected polymer powder without significantly altering their physicochemical properties.

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Among the binders which can be advantageously used within the scope of the invention, as examples which are not limited in nature, mention may be made of:

25 - Polyvinylpyrrolidones marketed by GAF under the trade names PVP K

30 and PVK K 90; Polyvinylpyrrolidones and copolymers of vinylpyrrolidone acetate marketed by BASF (Federal Republic of Germany) under the trade name Luviskol K30 to K 90; and hydroxypropylcelluloses marketed by HERCULES (USA) under the tradenames Klucel H, M, G, J, L and E.

35 Although a surfactant may not be required, it has been found to have a beneficial effect, in particular for the good preservation of the spreading compound and for facilitating the application in the preparation of the alloy material.

It is preferable to use an anionic or non-ionic agent as the surfactant.

Among the surfactants available within the scope of the invention, as are non-limiting examples, the following may be mentioned:

Product marketed by Rohm and Haas (USA) under the brand names Triton X 100 and Triton GR 5 M; Product marketed by BYK-MALLINCKRODT under the brand name ANTI-TERRA-15 U; A product marketed by PETROCHEMICALS CO., INC. Under the tradename MOR-WET EFN; 20 - Products marketed by AIR PRODUCTS under the brand name SURFYNOL; and a product marketed by BASF (Federal Republic of Germany) under the trade name Leophen RA.

The thickness of the top layer is preferably 10-100 .mu.m.

In the case of the use of sealant, the medium or high voltage power cable industry has · '. it is preferred to use electrically conductive alloy materials with acceptable electrical. 30 to achieve conductivity inside and on the material.

Usually, a fixed and flat support is first provided with a material that allows a suitable surface and transverse resistance to be achieved for the type of cable in question (usually 8-20 g / m2 carbon black conductors are sufficient; they are placed on the support during its manufacture).

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As shown below, the alloy material according to the invention can be prepared by applying a pulp to the support. This mass, and this is one of the advantages of this process, may contain electrically conductive carbon black, which the resulting moisture-expandable coating layer preferably contains from 2 to 8 g / m 2. This procedure helps to avoid the "bi-face" effect, and nevertheless achieves homogeneous electrical conductivities for each surface and the entire thickness of the material.

The invention further relates to a stronger alloy material used as a sealant for electric cables for the transmission of medium or high energy, characterized in that the cover layer formed by it contains, inter alia, 2-8 g / m 2 of electrically conductive carbon black.

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The alloy material according to the invention can be prepared by applying to at least one surface of the support a mass containing a moisture-expandable polymer powder, a water-soluble binder and a selected surfactant for the coating layer in a predetermined ratio and optionally other additives and / or carbon black homogenized by means of which the liquid then becomes evaporated.

The application must be carried out by means of a conventional application device, which mainly comprises a pulp tank and drive rollers, as well as roller scrapers on a support base.

Evaporation of the liquid must be carried out in a drying room operated, for example, by means of hot air.

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The solidity (viscosity) and homogeneity of the liquid used to achieve the dispersion of the moisture-expandable polymer and the various additives needed to provide a suitable mass allow the application to be performed without the moisture-expandable polymer expansion step. This liquid is preferably selected from light alcohols of the methanol or ethanol type.

The invention relates, inter alia, to an application compound for the preparation of the mixture-5 material according to the invention, characterized in that it contains essentially the weight percentages of the following ingredients: 57-16.5% of a polymer powder which expands under the influence of moisture; - 1.5-13.8% of surfactant; 10 to 13.2% of surfactant; - 0-14.4% electrically conductive carbon black; and - 40-70% homogenizing liquid.

This pulp is prepared by first dissolving the water-soluble binder in the homo-15 generating fluid and then sequentially adding the surfactant in question, the moisture-expandable polymer, and possibly other substances such as electrically conductive carbon black. The viscosity of the application compound according to the invention is always adapted to the nature of the binder used so that the application is easy to carry out and that the coating layer obtained is appropriate and well adhered to the support.

As already described above, the material according to the invention may contain various embodiments.

::> 25 This material can thus be used to absorb water or physiological fluids used mainly in medicine, surgery and healthcare.

30 It can also be used in agriculture to enhance germination in order to keep the water where the seeds are placed, and this precise arrangement is particularly important because the water is rich in growth-promoting substances such as nutrients. Such substances containing, for example, spore and fungicidal ingredients and fertilizers 35 can also be easily added to the mixture material during its application.

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The alloy material according to the invention can also be used for planting seedlings. The seedlings are placed together with the soil in the mixture material and planting can safely take place after immersion in water.

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As described above, an important further application of the alloy material according to the invention is its use in cables to ensure their longitudinal tightness.

Referring to Figures 1 and 2 of the accompanying drawings, the use of an alloy material according to the invention in shielding a cable in the event of water accidentally penetrating transversely through the outer sheath of the cable will now be described.

The alloy material 1 according to the invention comprises a water-permeable support substrate 11 and a cover layer 12 containing primarily a moisture-expandable polymer and a water-soluble binder, this cover layer being interposed between the outer sheath 2 of the cable and the core or more generally the inner sheath. The cable parts 2 and 3 20 move more or less relative to each other during the use of the cable (Fig. 1).

When water accidentally penetrates the cable (Fig. 2) transversely to the sheath 2 and the alloy support base 11, it dissolves the water-soluble binder in the vicinity of its point of penetration. The moisture-expandable polymer attached to the support by the soluble binder detaches from the support and coagulates around the water penetration point, forming a seal 13 which prevents water from entering the cable.

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Under the influence of moisture, the expandable polymer, which is no longer protected by the binder, is able to swell to its full extent and may be less in amount compared to previous solutions, as it efficiently accumulates in the vicinity of the water penetration zone.

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It is to be understood that this description has been given by way of example only, and that other arrangements in particular may be used within the cable without departing from the scope of the present invention.

Figures 3 and 4 show embodiments in which the previously known alloy materials described above are used.

Such a blend material 4 comprises a thermoplastic material-coated polymer layer 41 of water-insoluble moisture, sandwiched between two layers of nonwovens 42 and 43.

When water inadvertently penetrates the cable, the moisture-expandable polymer expands in the direction of water penetration without detaching from the support substrate, forming an "expansion" 44 on this particular surface, but unable to form a seal around that penetration point.

However, the resulting shielding of the cable is less effective than in the solution according to the invention, and due to the fact that the polymer in question cannot be expanded with its full force, mainly due to the presence of a thermoplastic binder, it is forced to use larger amounts.

The following examples relating to the composition of the spreading compositions and the preparation of the compounding composition according to the invention are given only as examples of a non-limiting nature.

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Example 1: application mass

Ingredients: Weight percent - Moisture expandable polymer 5 AQUALIC CA, JAP.CAT.CHEMICAL ... 100 - Water soluble binders

Polyvinylpyrrolidone K 30, GAP 12

Hydroxypropylcellulose 10 KLUCEL M, HERCULES 3 - Surfactant LEOPHEN RA, BASF 10 - Electrically conductive carbon black VULCAN PF, CABOT 5 15 - Homogenizing liquid METHANOL 150 This mass is prepared as a mixture, the ingredients of which are added in the above order.

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Example 2: application mass

Ingredients: Weight percent - Moisture expandable polymer WATERLOCK J550, GRAIN PROCESSING 100 - Water soluble binder:

Polymer hydroxypropylcellulose KLUCEL, HERCULES 20 - Surfactant 30 ANTI TERRA U, BYK MALLINCKRODT 10 - Methanol 100 35 11 85604

Example 3: Preparation of a blend material according to the invention The support used is a non-woven material made of polyester fibers and a binder SBR. The fibers should preferably be parallel.

The spread is prepared according to Example 1, either in a suitable mill or mixer, according to the granularity of the selected polymer powder to obtain a solid mixture. If necessary, electrically conductive carbon black is added to the binder to achieve surface resistances on the order of 1500-3000 ohms / cm2.

This mixture is applied using a roller scraper system. The layer thickness is determined to be 78 g / cm 2, whereby after oven drying, a moisture-expandable polymer coating with a size of 60 g / cm 2 is obtained.

The result is thus a blend material comprising a thin layer of synthetic polymer laid on a support network made of nonwoven material in a network and water-like manner. Such a layer is characterized by the encapsulation of a hydrophilic polymer.

Upon contact with water, the encapsulation disappears, exposing the hydrophilic polymer. The result is complete and rapid swelling. At the same time, the superabsorbent polymer detaches from the nonwoven substrate. This movement of the coagulated polymer occurs in the direction of the main water passage zones, ensuring excellent sealing efficiency of the polymer.

Another advantage of encapsulation is that such a tape is more resistant to storage under strong relative humidity.

35 12 S 9 6 0 4 Practical tests

Example 4: high voltage cable containing the alloy material 5 prepared according to Example 3

This is a 36 KV cable. The experiment was performed with a 3 m long cable, the center of which was cut longitudinally up to the strip inserted between the core of the cable and the extruded semiconductor coating, with the application occurring outwards.

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The cable was subjected to various test cycles, each of which included a 6 h test under stress at 90 ° C and then a post-cooling test at ambient temperature for 6 h, for a total of 12 h test.

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Experimental performance - six cycles (72 h) without water - 28 cycles (336 h) with running water at a pressure of about 8,103 20 (800 mm of water).

Result

Water penetration into surgery: 14-22 cm.

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Example 5: Telephone cable containing the alloy material of Example 3

This is a cable "20 pairs 6/10". The experiment was performed with a one meter 30 meter cable. The tape was placed longitudinally after the liner oil gelatin and polyester film were applied, with the application being outward.

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Execution of the test

Running water was allowed to flow over the cable for two months.

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Result

The average water penetration was 10 cm (maximum value 15 cm).

In summary, the invention makes it possible in particular to achieve: - good operating efficiency, - a small and regular layer thickness, 15 - cutting the strip into sections of about 5 cm in length, - under the action of a dense massage gel, - gel accumulation in the vicinity of the main water passages, - the formation of a water-preventing gel which is not slowed down by rising or falling temperatures, 20 - the protection of the water-soluble substance by encapsulation during storage.

Claims (12)

1. Mixture material, mainly sonic, etc., forms solid and even support substrate having at least one coating layer on the surface, comprising a polymer powder so as to expand through the action of moisture, which is attached to the support substrate by the mediation of a water-soluble binder, characterized therein. that said coating layer mainly contains: 10 - 95-55% by weight of polymer powder which expands by the action of moisture; 5-23 weight percent water-soluble binder; and 0-22% by weight of surfactant. 2. Mixing material according to claim 1, characterized in that said support substrate is flexible. Blending material according to claim 1, characterized in that said support substrate is a felt material. 20 4. A blend material as claimed in claims 1-3, characterized in that the polymer expanding through the action of moisture is selected from a group comprising modified acrylic polymers, refined starches, polyacrylamides, carboxymethyl cellulose and its derivatives. 5. Mixing material according to claim 1, characterized in that the material which expands by the action of moisture is so absorbent that the former sucks water 30 at least 15-fold compared to its own weight. 6. A blend material as claimed in claims 1-5, characterized in that the water-soluble binder is selected from a group comprising polyvinylpyrrolidones and their copolymers and hydroxypropyl cellulose. 17 8 9 604 7. A blend material as claimed in claims 1-6, characterized in that said surfactant is anionic or nonionic. Mixing material according to claim 1 of claims 1-7, intended to be used as a sealing agent in power cables which transmit energy of medium voltage and high voltage, characterized in that said coating layer contains, among other things, 2-8 g / m2 of conductive carbon black. 10 9. Preparation process for the blend material according to claim 1, characterized in that it comprises coating of at least one pulp surface containing pulp comprising a polymer powder which expands by the action of moisture, water-soluble binder and selected surfactant. Preselected conditions and possibly also other additives and / or carbon-homogenized with the aid of some liquid other than water and evaporation of this liquid. 20 10. A process according to claim 9, characterized in that said homogenizing liquid is selected from the group of lower alcohols, most preferably methanol or ethanol. Distribution mass for carrying out the process according to claim 9 or 10, characterized in that it mainly comprises the following ingredients: 57-16.5% by weight of polymer powder which expands by the action of moisture; 30 - 1.5-13.8% by weight water-soluble binder; 0-13.2% by weight of surfactant; - 0-14.4% by weight of conductive carbon black; and 40-70% by weight of homogenizing liquid. Use of the blend blank as claimed in claims 1-8 as a sealant in cables.