EP0228004B1 - Electrically conductive floor construction - Google Patents

Abstract

An electrically conductive flooring and method for constructing same upon an existing flooring, which comprises sequential layers of: a nonwoven base layer; an electrically conductive coating layer; an electrically conductive adhesive layer; and an antistatic or electrically conductive top layer; a copper band is optionally located within the coating layer and/or adhesive layer.

Description

The subject of the present industrial property right is an electrically conductive floor construction, consisting of a customary usable floor, which has a textile or plastic covering as the top layer and which combines good heat insulation with pleasant elastic accessibility.

From DE-A-1790224 a floor structure is known in which a foundation or leveling layer is applied to a screed on a screed. On this compensation layer there is an electrically conductive layer, on which in turn a plastic top layer containing aluminum powder is applied as a useful covering.

In addition to the other qualities that are required of a floor covering, the property of its electrical conductivity of a useful covering comes more and more to the fore. When walking on non-conductive flooring, the walker is electrostatically charged, especially in dry air. On the one hand, this electrostatic charge can lead to unpleasant discharges if the person walking on the floor touches electrically conductive objects and, in addition, also leads to malfunctions in running computer programs or even ignites explosive solvent-air mixtures.

In the technical field in particular, therefore, conductive useful coverings have already been used, in which an earthed copper strip construction, in particular a copper network, is arranged under the actual top cover. In the case of PVC tiles, it is necessary in this case to lay the nets or intersecting copper strips in such a way that the copper strips cross in the middle of the tiles, so that a particularly electrically conductive point is arranged under the middle of the tile. To simplify this rather complex construction, attempts have already been made to use conductive fillers or use conductive primers. In these cases, however, it is a prerequisite that there is a firm sub-floor that complies with DIN 18365 for floor work.

In order to create the conditions for laying a good conductive floor, the old coverings had to be removed completely. However, this is associated with considerable effort, since adhesive residues easily adhere to the sub-floor and, particularly when they are older, can be removed only with difficulty. It has therefore often been necessary to accept mechanical removal of the sub-floor, a process that is associated with noise and dust.

The object of the present invention was therefore initially to find a new method or a new construction of an electrically conductive floor, which can be applied without complex removal of the old floor construction. The construction of copper strips and copper wire nets to be applied with the usual means had to be abandoned and a possibility of the desirable application of a new electrically conductive useful covering to an old covering that could not be removed had to be found.

• a) einen mit einseitiger Haftklebeschicht versehenes Verlegevlies mit der Haftschicht auf den vorhandenen Nutzbelag und darauf
• b) einen elektrisch leitfähigen Anstrich sowie
• c) einen elektrisch leitfähigen Kleber und zuletzt
• d) einen antistatisch ausgerüsteten oder elektrisch leitfähigen Nutzboden.

This object was achieved in that the following coverings were applied directly to an existing, customary cover, consisting of a textile or plastic cover, without removing it:

• a) a laying fleece provided with a one-sided adhesive layer with the adhesive layer on the existing floor covering and on top of it
• b) an electrically conductive paint and
• c) an electrically conductive adhesive and last
• d) an antistatic or electrically conductive floor.

• a) ein mit einseitiger Haftklebeschicht versehenes Verlegevlies mit der Haftschicht auf den vorhandenen Nutzboden (A) und darauf
• b) ein elektrisch leitfähiger Anstrich sowie
• c) ein elektrisch leitfähiger Kleber und zuletzt
• d) einen antistatisch ausgerüsteten bzw. elektrisch leitfähigen Nutzboden.

The subject of the present industrial property right is therefore an electrically conductive floor construction that has the following electrically conductive new useful floor covering (B) on an existing, no longer fully functional old covering (B), which has the following structure from the top of the old covering as follows:

• a) a laying fleece provided with a one-sided adhesive layer with the adhesive layer on the existing useful floor (A) and on top
• b) an electrically conductive paint and
• c) an electrically conductive adhesive and last
• d) an antistatic or electrically conductive floor.

The laying fleece (a) provided on one side with a pressure-sensitive adhesive layer is preferably a random fleece made of polypropylene, polyethylene, polyterephthalate or polyamide fibers. The entire plastic fleece should have a weight between about 40 g / m² and about 250 g / m², in particular from 60 to 120 g / m². A dispersion whose films have a high surface tack is particularly suitable as a PSA coating.

This electrically non-conductive plastic fleece or only relatively poorly conductive plastic fleece is first provided with a conductive coating which is applied in the form of a coat of paint. This conductive paint (primer) contains carbon black or graphite as the active substance. Primarily synthetic or natural latices are used as binders. The use of polychloroprene or polybutadiene styrene or polybutadiene acrylonitrile latex has proven its worth. They expediently also contain rosin derivatives or other hydrocarbons or terpene or balsam resin in dispersed form known as "tackifiers". It is also possible to use conventional additives such as zinc oxide, chalk or barium sulfate. The aforementioned also imparting conductivity Substances are expediently used as commercially available dispersions, with the usual wetting agents and emulsifiers naturally having to be present in the system. The primer, which can be applied by roller or by spraying, is allowed to dry for about 3 to 24 hours, preferably 5 to 12 hours, depending on the temperature and air movement.

The glue is then applied to this primer. Thin copper strips about 1 to 2 m long are inserted into the adhesive or even in the primer for electrical grounding. This is to ensure proper discharge of the load caused by people walking on it. It is sufficient to insert a copper tape on about 20 to 35 m². The tape itself should be about 0.05 to 0.25 mm thick. An average thickness within the above limits and a width of 5 to 15 mm is sufficient. The entire floor construction is grounded by gluing thin, approximately 1 m long copper strips for 30 m² each. The electrically conductive adhesives which are used for the new process or for the construction of the new construction should contain a conductive substance such as carbon black, graphite, copper or possibly silver powder.

Aqueous dispersions of polyacrylic acid esters, in particular copolymers of acrylic acid esters of medium chain length (C _3-8 ) and vinyl acetate, have proven to be favorable as binders for the actual adhesive. You can also use copolymers with predominant proportions of vinyl acetate and minor amounts of ethylene, propylene and / or acrylic acid esters. It is also possible to use latices made of natural or synthetic elastomers, such as polystyrene butadiene. Such basic dispersions should also be the typical ones for adhesive systems Preservatives for preservation, anti-aging agents and fillers, e.g. chalk, quartz powder, barium sulfate, zinc oxide or titanium dioxide, which have a direct beneficial effect on the strength or resistance to stress on the adhesive joint. The carbon black should be added to the adhesive as a commercially available dispersion and should be present in an amount of about 3 to 10 percent by weight, based on solids.

In the adhesive applied by means of a conventional toothed spatula or in a known manner in an amount of 100 to 600 g / m², in particular 250 to 500 g / m² (wet), the actual floor covering should be inserted after a short period of time.

Of course, the covering itself has to meet high electrical conductivity requirements. Carbon black or graphite-containing PVC and rubber coverings are used as electrically conductive elastomer coverings or elastic floor coverings. Antistatic floor coverings are made on the basis of PVC as well as textile floor coverings. Antistatic PVC coverings contain moisture-retaining chemicals, while antistatic textile coverings can be produced using steel fibers and carbon fibers.

example 1

The surface consisted of a velor carpet with a jute back, which was firmly glued to the screed. The carpet was carefully cleaned using a vacuum cleaner.

First, a polypropylene fleece of 75 g / m² basis weight of a one-sided PSA coating (150 g dry / m²) was applied. The pressure sensitive adhesive consisted of an acrylic acid ester copolymer (Acronal V 205, BASF) containing carboxyl groups. The dispersion had a solids content of 70%, pH 4 and 1200 mPa · s at 23 ° C. (Contraves rheometer).

The electrically conductive paint was then applied to the fleece with a roller in an amount of 200 g (wet) over 1 m². The dispersion was composed of 42% by weight of a polychloroprene dispersion (Neoprene latex 115 DuPont),
30% by weight of natural resin dispersion (rosin derivative dispersion No. 5786 from Hercules) and 28% by weight of a 25% carbon black dispersion (Derussol AN Degussa). It also contained the usual anti-aging agents, preservatives and protective colloids. The pH was 9. A dried paint had a resistance of less than 3 · 10⁵ Ohm according to DIN 53276.

A 1 m long copper tape measuring 1 m × 0.2 mm was placed in the still wet paint in the 30 m² rehearsal room in order to be grounded later.

After the paint had dried on (12 hours), an electrically conductive adhesive was then applied with the notched trowel (A3: tooth space depth 1.65 mm, tooth space width 1.5 mm, Dental bridge width 0.5 mm) applied in an amount of 300 g / m² (wet). The adhesive had the following composition:
25% by weight aqueous 60% dispersion of a copolymer of acrylic esters with vinyl acetate (commercial product Aeronal V 303 BASF)
2 wt% monobutylene of triethylene glycol
4% by weight xylene
10% by weight rosin (dispersed)
18% by weight of chalk
9% by weight quartz flour
32% by weight carbon black dispersion (25% by weight as a commercial product Derussol AN1-25 / II from Degussa)
This adhesive had a resistance of less than 3 · 10⁵ ohms after drying. Electrically conductive PVC sheets of 2 mm thickness (Mipolam ^R 480 CE) with dimensions of 60.8 × 60.8 cm were then placed in the still moist adhesive bed. After 1 week, the conductivity of this floor construction was measured to be 1 × 10⁶ ohms.

Example 2

There was a needle-fleece floor that was carefully cleaned with a vacuum cleaner. The laying fleece of Example 1, which had been provided with pressure-sensitive adhesive on one side, was applied, and the soot-containing polychloroprene coating from Example 1 was then applied. After it has dried overnight, the conductive carpet adhesive is applied with the spatula (B1: tooth gap depth 2.1 mm, tooth gap width 2.3 mm and tooth bridge width 2.7 mm); the adhesive application is 400 g / m² wet.
The conductive adhesive has the same composition as in Example 1.

Claims (9)

1. An electrically conductive floor construction, in which the following coverings lie directly on an existing, standard wearing surface in the form of a fabric or plastic covering:
   

   a) a nonwoven covering provided on one side with a layer of contact adhesive with the adhesive layer on the existing wearing surface,

   b) an electrically conductive primer or paint,

   c) an electrically conductive adhesive and, finally,

   d) an antistatically treated or electrically conductive wearing surface.
2. An electrically conductive floor construction as claimed in claim 1, characterized in that, for every 20 to 35 square metres of floor area, one copper band measuring 0.05 - 0.25 mm x 5 - 15 mm for a length of 1 to 2 metres is placed on the primer and/or on the adhesive layer.
3. An electrically conductive floor construction as claimed in claims 1 and 2, characterized in that the primer or paint consists of polychloroprene containing carbon black.
4. An electrically conductive floor construction as claimed in claims 1 to 3, characterized in that the conductive adhesive consists of carbon-black-containing emulsionbased adhesives based on acrylate copolymers, on vinylacetate-acrylate copolymer dispersions or on synthetic or natural latices.
5. A process for making up the electrically conductive floor construction claimed in any of claims 1 to 4, characterized in that the following layers are directly applied to a standard wearing surface in the form of a fabric or plastic covering without removing the latter:
   

   a) a nonwoven covering provided on one side with a layer of contact adhesive with the adhesive layer on the existing wearing surface,

   b) an electrically conductive primer or paint,

   c) an electrically conductive adhesive and, finally,

   d) an antistatically treated or electrically conductive wearing surface.
6. A process for making up an electrically conductive floor construction as claimed in claim 5, characterized in that, for every 20 to 35 square metres of floor area, one copper band measuring 0.05 - 0.25 mm x 5 - 15 mm for a length of from 1 to 2 metres is placed on the primer or paint.
7. A process for making up an electrically conductive floor construction as claimed in claims 5 and 6, characterized in that a polychloroprene-based adhesive containing carbon black is used.
8. A process for making up an electrically conductive floor construction as claimed in claims 5 to 7, characterized in that a carbon-black-containing emulsion based on vinylacetate-acrylate copolymers or other modified polyacrylates or synthetic latices, such as polychloroprene or polybutadiene-styrene for example, is used as the conductive adhesive.
9. A process for making up an electrically conductive floor construction as claimed in claims 5 to 8, characterized in that commercial, non-conductive emulsion-based adhesives of the raw materials mentioned in claim 8 are made conductive in situ by means of additives which impart conductivity.

Images