DE102017219096B4 - Cable containing a water indicator system and manufacture of the cable, and manufacture and use of a water indicator thread - Google Patents

Abstract

The present invention relates to a water indicator thread for detecting water, for example in a cable. Furthermore, the invention relates to processes for the preparation of the water indicator thread, as well as its uses.

Description

The present invention relates to a water indicator thread for detecting water, for example, water that has entered a cable, and a cable containing a water indicator system. Furthermore, the invention relates to methods for producing the water indicator thread or cable, as well as its uses.

State of the art

Depending on the application, cables are equipped with a system that gives a visual warning when water enters. Water can, for example, by defects or injuries, in the insulation, including grounding cables occur.

There are indicator systems for water in cables based on hydrochromic materials which produce a slight color change on contact with water. However, this color change is visually difficult to see and / or health-endangering materials are used (in particular metal salt compounds such as CuSO ₄ ). In addition, the color change in systems previously used is sometimes only in a few shades of gray. Often, these materials are also difficult to attach mechanically to a substrate. This can lead to (toxic) dust formation / contamination during further processing. In the case of paper substrates, the products often suffer from insufficient mechanical strength.

The known systems are also often unable to survive the cable manufacturing process unscathed. In particular, the mechanical and thermal resilience of the systems is not particularly high. However, water-sensing yarns are required for use in cable production, which survive the processing process unscathed and, in use, can produce a strong, irreversible color change on contact with water.

In addition, some indicator threads do not have a 100% area coverage of the coloring signal thread. In addition, they are often very expensive to produce (elaborate braiding and low production speed).

The DE 10 2015 011 620 A1 relates to a ground wire, consisting of at least one, composed of a plurality of individual wires flexible conductor cable, which is provided with an insulating, at least partially transparent sheath. According to the invention, a substance is provided or incorporated on or in the conductor cable, which upon contact with atmospheric moisture and / or water as a result of a chemical reaction triggered thereby leads to a color change or coloration of the environment of the conductor cable, which is visually recognizable by the transparent sheath. There is no disclosure of a water indicator system which comprises a colored agent which is under a cloudy, water-soluble polymer layer.

WO 96/34511 A1 discloses a heating cable sealed at one end. A display strip is disposed between the cover and the conductor to provide a visual indication of an adverse physical condition, such as the ingress of water. The element is connected to a power cable by a splice vented to the outside of the element adjacent to the splice. There is no disclosure of a water indicator system which comprises a colored agent which is under a cloudy, water-soluble polymer layer.

EP 1 840 046 A1 discloses a package of a flexible or semi-flexible or rigid packaging form, characterized in that the package comprises an apparatus integrated in or applied to the packaging material for indicating the change in temperature in the form of a coating or print which is in contact with condensing and / or re-freezing Moisture exhibits an irreversible color change. A cable is not disclosed.

DE 30 45 418 (A1) describes a plastic or rubber-insulated electrical cable which has a line core ( 1 ) and a surrounding protective jacket ( 2 ), characterized by at least one within the shell ( 2 ) longitudinal continuous indication element ( 9 ), which causes a visible change by the influence of moisture. The cable according to the invention is not obvious.

In view of the above-mentioned problems, therefore, there was a need to provide an improved cable with water indicator system, as well as methods for its production.

Summary of the invention

The present invention is based on the use of a colored agent wherein the visibility of the colored agent indicates the presence or former presence of water. The colored agent, for example a signal thread, is covered in the dry state by a cloudy, soluble polymer layer. Upon contact with water, the cloudy polymer layer becomes transparent, or dissolves or is at least dissolved (ie partially dissolved). In contrast to the prior art thus no color change of the colored agent necessary.

Basically, the water-soluble polymer is transparent and can not obscure the colored agent as a transparent polymer layer. In order to coat the colored agent, for example the signal thread, with the polymer in the form of a cloudy layer, a refraction of light must be generated in the polymer layer. This is achieved either by applying the polymer to the signal thread as a nonwoven, for example, or by foaming it around the signal thread. In addition, it is also possible to apply the polymer by flocking / spraying fibers or powder. However, it is preferable to a fiber composite, since due to the capillary effect, the water is then absorbed quickly. The refraction of the water-soluble polymer is then no longer transparent and the signal signal is hidden. On contact with water, the material dissolves and the colored agent, or the signal signal becomes visible.

An advantage of the inventive cable with water indicator system is the high mechanical strength that can be achieved. In addition, a variety of signal / warning colors can be used. Advantageously, the production on standard equipment, such as standard extrusion equipment for the production of foamed layers, and in a simple manner possible. A nonwoven can be applied by winding, for example. Thus, it is a low cost system with a simplified manufacturing overhead compared to the prior art. In particular, health-endangering materials can be avoided.

• - mindestens eine Ader;
• - mindestens ein Wasserindikatorsystem; und
• - mindestens einen transparenten Außenmantel, und

wobei das Wasserindikatorsystem durch den mindestens einen transparenten Außenmantel sichtbar ist und ein farbiges Mittel aufweist, das (im trockenen Ausgangszustand) unter einer trüben, wasserlöslichen Polymerschicht befindlich ist.The present invention thus relates to a cable comprising:

• - at least one strand;
• - at least one water indicator system; and
• - At least one transparent outer jacket, and

wherein the water indicator system is visible through the at least one transparent outer jacket and has a colored agent which is (in the dry initial state) under a cloudy, water-soluble polymer layer.

In addition, the invention relates to the preparation (claim 9) and use (claim 8) of a Wasserindikatorfadens, and a method for producing the cable according to claim 11.

Detailed description of the invention

1. 1. Kabel, aufweisend:
   • - mindestens eine Ader;
   • - mindestens ein Wasserindikatorsystem; und
   • - mindestens einen transparenten Außenmantel, und

wobei das Wasserindikatorsystem durch den mindestens einen transparenten Außenmantel sichtbar ist und ein farbiges Mittel aufweist, das (im trockenen Ausgangszustand) unter einer trüben, wasserlöslichen Polymerschicht befindlich ist.The present invention relates to the following embodiments of a cable:

1. 1. Cable, comprising:
   • - at least one strand;
   • - at least one water indicator system; and
   • - At least one transparent outer jacket, and

wherein the water indicator system is visible through the at least one transparent outer jacket and has a colored agent which is (in the dry initial state) under a cloudy, water-soluble polymer layer.

In order for the invention to achieve its advantages, the cloudy, water-soluble polymer layer must be located between the colored agent and the at least one outer sheath. In this case, a change in the state of the water indicator system can be detected without removing the outer jacket.

In one embodiment, the cable is a grounding cable. In principle, however, the water indicator system can be used with any cable with a transparent outer sheath.

2. The cable according to embodiment 1, wherein the colored agent is a signal thread, preferably a colored polymer strand, or a colored fiber, for example natural fiber, wherein the cloudy, water-soluble polymer layer is applied to the colored polymer strand or dyed fiber.

Preferably, the water indicator system is a water indicator thread or an elongated signal element, which is preferably as in 1 shown, is constructed. But it is also possible to provide an already stranded and possibly sheathed cable with a color layer and polymer layer, and optionally then with a transparent sheath.

According to the invention, the colored agent can be optically detected through the outer shell as soon as the turbid, water-soluble polymer layer comes into contact with water and in particular dissolves or at least dissolves (i.e., partially dissolves), i. becomes transparent or releases the view of the colored medium. After dissolution or dissolution, the polymer-containing solution can dry again, the resulting polymer layer then being given a structure which is no longer cloudy but more transparent than in the initial state.

The terms "cloudy" and "more transparent" in this context refer to two states of the water indicator system. The dry initial state (before contact with water) corresponds to a cloudy state of the polymer layer in which the colored agent is not or less visible. The "more transparent" state after dissolving or dissolving the polymer layer, optionally after re-drying the dissolved or dissolved polymer layer corresponds to a dry or wet state (after contact with water), in which the colored agent is visible or better visible than in the initial state is. According to the invention, the contact of the water indicator system with water therefore improves the visibility of the colored agent, even if the water dries again. This improved visibility can be optically detected by eye or a measuring system. In other words, it is not necessary for the cloudy polymer layer to completely obscure the colored agent, or for the polymer layer to be completely removed or completely transparent after contact with water. The more transparent state can be achieved here at one or more points, or even over the entire surface, of the water indicator system.

• Zum Einen minimiert die Benetzung mit Wasser die Lichtbrechung und das farbige Mittel wird besser sichtbar. Zum Anderen löst das Wasser das Polymer an oder sogar auf. Dies führt dazu, dass die Struktur der transparenten Schicht, z.B. die Schaumstruktur/„Fasergeflecht“, verloren geht. Auch dies führt zu einer erhöhten Transparenz, bzw. einer besseren Sichtbarkeit des farbigen Mittels.

According to the invention, the previously cloudy, water-soluble polymer layer, for example a milky white PVA layer, preferably within fractions of a second, becomes transparent upon contact with water and thus releases a direct view of the underlying signal signal. Two effects come into play at the same time:

• On the one hand wetting with water minimizes the refraction of light and the colored agent becomes more visible. On the other hand, the water dissolves or even dissolves the polymer. As a result, the structure of the transparent layer, eg the foam structure / "fiber braid", is lost. This also leads to increased transparency, or better visibility of the colored agent.

If the water is removed by drying / evaporation, a transparent polymer film remains. Thus, in the long term, the wetted with water body is irreversibly transparent.

3. The cable according to embodiment 1 or 2, wherein the cloudy, water-soluble polymer layer comprises or consists of one or more polymers of the following group, polymethacrylic acid, polyacrylic acid, polyethylene oxide, polyvinylpyrrolidone or cellulose-based polymers, polyvinyl alcohol (PVA), polyacrylamide, polysaccharide , Poly-N-vinylpyrrolidone, preferably polyvinyl alcohol (PVA), polyacrylamide, polysaccharide, polyethylene oxide and poly-N-vinylpyrrolidone.

4. The cable according to one of the preceding embodiments, wherein the turbid, water-soluble polymer layer, preferably a polyvinyl alcohol layer (PVA), in foamed form, preferably by an extrusion process, is applied.

The preparation can be similar to the production of cables, for example, by a suitable signal signal (instead of a conductor) is coated in an extruder. In order to achieve optimum coverage of the signal thread in the dry state, for example, a sheath based on PVA with a wall thickness from 0.05 mm can be applied.

5. The cable according to one of the preceding embodiments, wherein the cloudy, water-soluble polymer layer, preferably a polyvinyl alcohol (PVA) has been applied as a tile.

The application of the polymer layer can be carried out using standard methods. In the case of an indicator thread, the banding (wrapping) of the thread with fleece offers itself. Here, the degree of coverage can be varied by varying the fleece width and the pitch. For example, the, available from the company Gunold ^®, Germany product "Solvy Fabric" can (made of 100% polyvinyl alcohol) or by the company Freudenberg (Performance Materials) product available DO 102 (nonwoven fabric insert, made of 100% polyvinyl alcohol) was used.

If a full color coat is to be covered, the nonwoven fabric may also be fed longitudinally during coat extruding prior to the extrusion step. Here, however, an overlap occurs on one side, so that the degree of coverage is different.

6. The cable according to any one of the preceding embodiments, wherein the cloudy, water-soluble polymer layer comprises or consists of a polymer having a degree of polymerization of 150-2500, preferably 150-1500, more preferably 150-800, on average.

7. The cable according to any one of the preceding embodiments, wherein the polyvinyl alcohol has a degree of hydrolysis (degree of saponification) of 70-100%, preferably 80-90 mol .-%.

8. The cable according to any one of the preceding embodiments, wherein the turbid, water-soluble polymer layer comprises or consists of a polymer having a solubility in water at 25 ° C of at least 300 g / L.

The following polyvinyl alcohols can be used, for example: polyvinyl alcohol 4- 88, 5-88, 8-88, 13-88, 18-88, 23-88, 26-88, 40-88, 47-88, and 56-88, preferably 88 ± 1%, for example, available from the company Kremer pigments, Aichstetten, DE (see 2 ).

In order to visualize the signal thread upon contact with water, it is preferable to use a polymer, preferably a PVA polymer, having a low degree of polymerization and hydrolysis. In addition, processing aids, such as antioxidants, may be added in an upstream compounding step. It is also possible to add further soluble or insoluble polymer species as long as the contact with water causes the color indicator according to the invention to be detected.

9. The cable according to one of the preceding embodiments, wherein the wall thickness of the cloudy, water-soluble polymer layer 0.05 mm - 4.0 mm, in particular 0.4-1.5 mm.

The present invention also relates to the following embodiments relating to the manufacture and use of a water indicator thread:

According to the invention, the water-indicator thread can either be the intermediate for a cable or another application, or it can be used directly as a water indicator in the sense of a final product.

With regard to the preferred embodiments of the water indicator thread, as well as its manufacture, reference is made to the above description of the cable, which in a preferred embodiment contains the water indicator thread.

10. Use of the water indicator thread according to the invention for producing a cable, preferably a ground wire.

To produce a cable / earthing cable, cable cores or stranded legs can be stranded together with the water indicator thread and then sheathed in a transparent manner.

The present invention also relates to the following embodiments for producing a water indicator thread:

• - einen gefärbten Polymerstrang, oder eine gefärbte Faser, oder ein farbigen Mittels, das auf ein Mittel in Strangform aufgebracht; und
• - eine darauf aufgebrachte trübe, wasserlösliche Polymerschicht, welche bei Kontakt mit Wasser transparent wird, wobei das Verfahren die Schritte aufweist:
  1. a) Bereitstellen eines farbigen Mittels in Strangform, oder eines farbigen Mittels, das auf ein Mittel in Strangform aufgebracht ist;
  2. b) Aufbringen einer trüben Schicht aus wasserlöslichem Polymer; und
  3. c) Aushärten der Polymerschicht um eine trübe, wasserlösliche Schicht zu erhalten.

11. A method of making a water indicator thread comprising:

• a colored polymer strand, or a dyed fiber, or a colored agent applied to an agent in strand form; and
• a cloudy, water-soluble polymer layer applied thereto which becomes transparent upon contact with water, the process comprising the steps of:
  1. a) providing a colored agent in strand form, or a colored agent, which is applied to a means in strand form;
  2. b) applying a cloudy layer of water-soluble polymer; and
  3. c) curing the polymer layer to obtain a cloudy, water-soluble layer.

The dyed fiber may be, for example, a natural fiber which may be applied to the cloudy, water-soluble polymer layer.

The manufacturing process can basically be performed as a standard method for producing strands. It is important in the method according to the invention that the product after the extrusion process, for example in the air, in inert gases or oils, cools, in particular with the exclusion of water, i. dry conditions.

12. The method of embodiment 11, wherein the cloudy layer of water-soluble polymer is applied as a film, or foamed about the colored article in extruded form, or extruded around the colored article applied to an agent in strand form. In the case of using a nonwoven this is cloudy before application. In a particularly preferred embodiment, the polymer is applied as extruded foam. This becomes cloudy due to the foaming process. In the case of an extrudable polymer, it is additionally possible to use stabilizers, fillers and nucleating agents (physical foam). In chemical foaming, blowing agents are additionally required, e.g. Azodicarbonamide and the like

In addition, the invention relates to:

1. i) Bereitstellen eines Wasserindikatorsystems, insbesondere wie hierin beschrieben,
2. ii) Verseilen des Wasserindikatorsystems mit mindestens einer ummantelten Ader, falls das Wasserindikatorsystem nicht bereits schon ein oder mehrere Adern enthält, und
3. iii) Aufbringen eines transparenten Außenmantels.

13. A method for producing a cable according to the invention, comprising the steps:

1. i) providing a water indicator system, in particular as described herein,
2. (ii) stranding the water indicator system with at least one sheathed wire if the water indicator system does not already contain one or more wires, and
3. iii) applying a transparent outer jacket.

With regard to the preferred embodiments of the water indicator thread to be produced, reference is also made to the above description of the cable.

The water indicator thread can be produced as a continuous strand. The water indicator thread may for example have a diameter of ≥ 0.5 mm.

1. a) Bereitstellen von mindestens einer Kabelader, die optional bereits ummantelt ist/sind;
2. b) Zusammenbringen der mindestens einen Kabelader mit dem erfindungsgemäßen Wasserindikatorsystem;
3. c) Aufbringen einer transparenten Ummantelung.

The present invention can also be used to manufacture a cable as follows:

1. a) providing at least one cable core, which is optionally already sheathed / are;
2. b) bringing together the at least one cable core with the water indicator system according to the invention;
3. c) applying a transparent sheath.

With regard to the preferred embodiments of the cable to be produced, as well as its manufacture, reference is also made to the above description of the cable.

list of figures

• 1 shows the structure of a Wasserindikatorfadens invention.
• 2 shows water-soluble types of polyvinyl alcohols.
• 3a-d show an indicator element before water contact (3a), directly after contact with water (3b), a few minutes after water contact (3c) and after drying after contact with water (3d).

Claims (11)

Cable comprising: - at least one strand; - at least one water indicator system; and at least one transparent outer jacket, and wherein the water indicator system is visible through the at least one transparent outer jacket and has a colored means (1) located under a cloudy, water-soluble polymer layer (2). The cable after Claim 1 , wherein the colored means is a signal thread (1). The cable after Claim 2 wherein the signal thread (1) is a colored polymer strand (1), or a colored fiber (1), wherein the cloudy, water-soluble polymer layer (2) is applied to the colored polymer strand (1) or the dyed fiber (1). The cable according to one of the preceding claims, wherein the cloudy, water-soluble polymer layer (2) comprises or consists of one or more polymers of the following group: polymethacrylic acid, polyacrylic acid, polyethylene oxide, polyvinylpyrrolidone or cellulose-based polymers, polyvinyl alcohol (PVA), polyacrylamide, Polysaccharide, polyethylene oxide, and poly-N-vinylpyrrolidone. The cable according to any one of the preceding claims, wherein the cloudy, water-soluble polymer layer (2) has been applied in foamed form. The cable according to any one of the preceding claims, wherein the cloudy, water-soluble polymer layer (2) comprises or consists of polyvinyl alcohol. The cable of any one of the preceding claims, wherein the cloudy, water-soluble polymer layer (2) comprises or consists of a polymer having a solubility in water at 25 ° C of at least 300 g / L. Use of a water indicator thread, comprising: a colored polymer strand (1), a dyed fiber (1), or a colored agent (1) applied to an agent in strand form; and - An applied cloudy, water-soluble polymer layer (2), in the manufacture of a cable. A method of making a water indicator thread comprising: a colored polymer strand (1), a dyed fiber (1), or a colored agent (1) applied to an agent in strand form; and a cloudy, water-soluble polymer layer (2) applied thereto which becomes transparent on contact with water, the process comprising the steps of: a) providing a colored agent in strand form (1), or a colored agent (1), which is applied to a means in strand form; b) applying a cloudy layer of water-soluble polymer; and c) curing the polymer layer to obtain a cloudy, water-soluble layer (2). The procedure according to Claim 9 wherein the cloudy layer of water-soluble polymer is applied as a fleece, or foamed about the colored means in strand form or about the colored means (1) which is applied to a means in strand form is extruded. Method for producing a cable according to one of Claims 1 - 7 comprising the steps of: i) providing a water indicator thread according to Claim 9 or 10 (ii) stranding the water indicator system with at least one sheathed wire if the water indicator system does not already contain one or more wires, and iii) applying a transparent outer jacket.

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