The present invention relates to a cover for a swimming pool or whirlpool and a slat and slat profile therefor.

More specifically the invention concerns such covers that are made of slats connected together, for example of plastic.

For a swimming pool cover these slats can normally float on the water in the swimming pool thanks to a number of airtight chambers in the slats, whereby the slats in turn are made of a slat profile that is closed with caps, or thanks to a foam filling in the slats.

Such swimming pool covers are known and are used in particular to prevent people, especially children, and/or animals falling into the swimming pool by accident, to keep leaves, insects and other dirt out of the swimming pool, and to ensure that the water in the swimming pool loses less heat, so that it warms up more quickly from solar heat or so that it needs to consume less energy to make and keep the water warm.

The same applies to a cover for a whirlpool, whereby the greatest difference is that the connected slats are generally kept a small distance above the water in a guide. The slats of such a cover are normally connected together in a hinged way by them all having a male connecting part and a female connecting part, whereby the male connecting part of a slat is placed in the female connecting part of an adjacent slat.

Alternatively covers are known whereby a flexible strip of plastic connects the slats and also acts as a hinge. With this type of cover a number of slats with their mutual connections are extruded in one go, whereby the combination of slats essentially consists of hard slat shells, a foam filling for them, and a flexible connection that is affixed in an integrated way in the slat shells.

A problem that occurs here is that water, for example rainwater or swimming pool water, can remain in hollows in the connecting part, especially the female connecting part, or on top of the flexible connection.

This stagnant water can easily be heated to relatively high temperatures.

While the swimming pool water or whirlpool water is normally treated such that microorganisms cannot develop well therein, if at all, there is relatively little exchange between the swimming pool or whirlpool water and the water in the female connecting parts or on top of the flexible connection.

As a result, the growth of microorganisms against the walls of the slat or on a connection between slats can easily occur, whereby algae in particular are the most visible, but also fungal growth or bacterial growth can occur that are just as undesirable.

This has an unattractive appearance and is unhygienic of course .

Such sections in which or on which the growth of microorganisms occurs are considered as possible sources of contamination by microorganisms for the swimming pool or whirlpool water itself.

Closed chambers in the slats can also suffer from this problem, albeit to a much lesser extent. Although the closed chambers are watertight, because they have to provide the buoyancy of the slats, the plastics used are somewhat permeable to water vapour by means of diffusion.

Upon cooling a small quantity of liquid water can thereby occur in these chambers, in which microorganisms can also grow.

The aforementioned slats can be executed in different colours of plastic. The problem is of course most visible in slats of transparent plastic.

Similar growth can also occur on other plastic components of such a cover, such as shafts, beams, bearings and partitions . The purpose of the present invention is to provide a solution to the aforementioned and other disadvantages by providing a cover for a swimming pool or whirlpool, whereby this cover comprises slats connected together that can be rolled out horizontally whereby these slats and/or connections for connecting these slats each have at least one growth-resistant part that has a surface that is oriented upwards when the cover is used, whereby there is a substance in or on the said surface that counteracts the development of microorganisms.

The growth-resistant part is hereby a part on which no growth of microorganisms takes place when used in a swimming pool cover, because its surface has a growth- resistant capacity. ^λ Ιη the surface' here means that in the material that forms the surface, there is such a substance immediately next to the surface.

For clarity it is noted that the said surface is a surface that can be exposed to air and water during use.

The advantage of the invention is that undesired growth can be avoided or reduced, such that the cover remains free of visually disturbing and unhygienic growth.

In a preferred embodiment the said slats are provided with a male and female connecting part for the connection of the slats together, and they each have at least one such growth-resistant part, whereby the substance that counteracts the development of microorganisms is at least in or on the female connecting part. This is useful because the female connecting part in particular is sensitive to growth.

In a preferred embodiment the said slats each comprise a plastic slat profile with at least one growth-resistant wall, whereby the growth-resistant wall or walls forms or form the growth-resistant part.

This is a practical, easily implementable embodiment of such slats because such a slat profile can be manufactured by extrusion.

Preferably the slat profile hereby comprises one or more chambers and it has a female connecting part with at least one aforementioned growth-resistant wall.

In another preferred embodiment the slat profile comprises two or more profile parts that extend over the entire length of the slat profile and which are separated from one another by the walls of the various profile parts being executed differently, whereby at least one profile part and at most the number of profiles less one, has an aforementioned growth-resistant wall.

This only enables one profile part to be made growth- resistant, for example the part that will be underneath during use. As a result, growth-resistant substance can be saved and the already existing production stages disrupted as little as possible. In this way a slat profile can be manufactured, for example by co-extrusion whereby not all profile parts need to be growth-resistant, and whereby for example a growth- resistant wall is only formed by a profile part that is not transparent, so that possible effects on the transparency are not visible.

As a result such an embodiment increases the flexibility of the designer of a slat profile.

In an alternative preferred embodiment the slats are connected by flexible plastic connections that extend over the length of the slats, whereby the connections form or comprise the said growth-resistant part.

The invention further concerns a slat for such a cover whereby this slat has at least one growth-resistant part that has a surface that is oriented upwards during the use of the cover, whereby there is a substance in or on the said surface that counteracts the development of microorganisms, whereby preferably the growth-resistant part is growth-resistant by the said substance being in the said surface, by it forming part of a plastic that, before the growth-resistant part is formed, is mixed with the said substance .

The invention also concerns the use of a substance that counteracts the development of microorganisms in or on a surface of an upward-oriented plastic slat or a plastic connection between slats of a swimming pool cover (1) or whirlpool cover that is made of slats connected together, whereby preferably the said substance is in the said surface, by the part of this slat or the connection that forms the said surface being made of a plastic that, before the part is formed, is mixed with the said substance.

For the cover, the slat, the slat profile and the use according to the invention, it is preferable that the substance that counteracts the development of microorganisms is a substance that counteracts the development of algae, and this because algae are the most visible of all types of growth.

Alternatively or additionally, the substance that counteracts the development of microorganisms can be a substance that counteracts the development of mould and/or bacteria .

Preferably the substance that counteracts the development of microorganisms is hereby silver or a silver compound, for example nanosilver or silver nitrate. This has the advantage that in general such products are not harmful to man and have little or no tendency to dissolve out of the slats, so that they remain active in the right place in the long term.

Other substances such as isothiazolinons, titanium oxide, zinc compounds and organic tin compounds such as tributyltin are also possible. Zinc pyrithione in particular turns out to work particularly well and has a low cost price. Alternatively the invention can be defined by the following clauses :

1. - Cover for a swimming pool or whirlpool, whereby this cover comprises slats connected together, whereby these slats and/or connections for connecting these slats each have at least one growth-resistant part that is growth- resistant by there being a substance in or on the growth- resistant part that counteracts the development of microorganisms .

2. - Cover according to clause 1, whereby the growth- resistant part is growth-resistant by being provided with a coating that contains the said substance.

3. - Cover according to any one of the previous clauses 1 to 7, whereby the growth-resistant part is growth-resistant by being made of a plastic that, before the growth-resistant part is formed, is mixed with the said substance.

4. Cover according to any one of the previous clauses, whereby the said substance is a substance that counteracts the development of algae.

5. Cover according to any one of the previous clauses, whereby the said substance is a substance that counteracts the development of mould.

6. Cover according to any one of the previous clauses, whereby the said substance is a substance that counteracts the development of bacteria. 7. - Cover according to any one of the previous clauses, whereby the said substance is silver or a silver compound.

8. - Cover according to any one of the previous claims whereby the slats are connected by flexible plastic connections that extend over the length of the slats, whereby the connections form or comprise the said growth- resistant part.

9. - Cover according to any one of the clauses 1 to 7, whereby the said slats are provided with a male connecting part and a female connecting part for the connection of the slats together and each have at least one such growth- resistant part.

10. - Cover according to clause 9, whereby the said substance is at least in or on the female connecting part.

11. - Cover according to clause 9 or 10, whereby the said slats each comprise a plastic slat profile with at least one growth-resistant wall, whereby the growth-resistant wall or walls forms or form the growth-resistant part.

12. - Cover according to clause 11, whereby the slat profile comprises one or more chambers and has a female connecting part with at least one aforementioned growth-resistant wall .

13. - Cover according to clause 11 or 12, whereby the slat profile comprises two or more profile parts that extend over the full length of the slat profile and which are distinguished from one another by the walls of the various profile parts being executed differently, whereby at least one profile part and at most the number of profile parts less one, has an aforementioned growth-resistant wall.

14. - Cover according to any one of the clauses 11 to 13 whereby the slat profile has a bottom wall that is growth- resistant on its top side.

15. - Cover according to any one of the clauses 11 to 14, whereby all walls of the slat profile are growth-resistant walls .

16. - Slat for a cover for a swimming pool or whirlpool, whereby this slat has at least one growth-resistant part that is growth-resistant by there being a substance in or on the growth-resistant part that counteracts the development of microorganisms.

17. - Slat according to clause 16, whereby it is provided with a male connecting part and a female connecting part for the connection to another identical slat.

18. - Slat according to clause 16 or 17, whereby the said substance is at least in or on the female connecting part.

19. - Slat according to any one of the clauses 16 to 18, whereby the growth-resistant part is growth-resistant by being provided with a coating that contains the said substance . 20. - Slat according to any one of- the clauses 16 to 19, whereby the growth-resistant part is growth-resistant by being made of a plastic that, before the growth-resistant part is formed, is mixed with the said substance.

21. - Plastic slat profile for manufacturing a slat for a cover for a swimming pool or whirlpool, whereby the slat has at least one growth-resistant wall that is growth- resistant by a substance being therein or thereon that counteracts the development of microorganisms.

22. - Slat profile according to clause 21, whereby the slat profile comprises one or more chambers and has a female connecting part with at least one aforementioned growth- resistant wall.

23. - Slat profile according to clause 21 or 22, whereby the slat profile comprises two or more profile parts that extend over the entire length of the slat profile and which are distinguished from one another by the walls of the various profile parts being executed differently, whereby at least one profile part, and at most the number of profile parts less one, has an aforementioned growth- resistant wall.

24. - Slat profile according to any one of the clauses 21 to 23, whereby all walls of the slat profile are growth- resistant walls. 25.- Use of a substance that counteracts the development of microorganisms in a component of a cover for a swimming pool or whirlpool.

26.- Use according to clause 25, whereby the component is a plastic slat or a connection between slats.

27. - Use according to clause 25, whereby the component is a cap for a slat, a partition, a shaft, a bearing or a beam or a plastic fastening means for these components.

28. - Use according to clause 25, whereby the substance is present in a sealant.

With the intention of better showing the characteristics of the invention, a preferred embodiment of a cover, a slat and a slat profile according to the invention is described hereinafter by way of an example, without any limiting nature, with reference to the accompanying drawings, wherein:

Figure 1 schematically shows a perspective view of a swimming pool cover according to the invention;

figure 2 shows a cross-section according to line II-II of a part of the swimming pool cover of figure 1; and figure 3 shows an exploded view of a component of the swimming pool cover.

The swimming pool cover 1 shown in the drawings essentially consists of a number of elongated slats 2 with a length L connected to one another side by side. The slats 2 each consist of a slat profile 3 of the right length L that is closed at both ends by a cap 4. These slat profiles are made of transparent PVC in which 2 percent by weight of dichloro-2-n-octyl-3-isothiazolinon, or DCOIT, is mixed.

This substance essentially has an anti-algae activity, but also an antifungal and antibacterial activity.

The slat profiles 3, and thereby also the slats 2, have a number of walls, in this example four slightly curved top walls that together form the top surface of a slat 2, four bottom walls 6 that together form the bottom surface of a slat 2, three partitions 7 and a side wall 8 that continues into a male connecting part 9 that has a double hook form.

The partitions 7 and end wall 8 define three chambers 10, which thanks to the caps 4 are closed chambers filled with air .

On the side opposite the male connecting part 9 the top wall 5 and bottom wall 6 are curved and an opening between the two is left open so that they form a complementary female connecting part 11.

The slats 2 are connected together by pushing the male connecting part 9 of a slat 2 into the female connecting part 11 of the adjacent slat 2. The slat profiles 3 are manufactured by heating a quantity of PVC until it is molten and then mixing it with 2 percent by weight DCOIT.

If desired, this can be done by using a master batch with a high concentration of this substance.

Then the slat profiles 3 are made by extrusion of the mixture thus obtained, followed by cooling.

Then these slat profiles 3 are cut to the desired length, after which caps 4, with a form that is largely complementary to the cross-section of the slat profiles 3, are affixed on the ends to form a slat 2. This is shown in figure 3.

In order to fasten these caps 4 and to make the chambers 10 of the slat 2 airtight, a quantity of sealant is first affixed to the caps 4.

The use of the swimming pool cover 1 is simple and as follows .

The swimming pool cover 1 is mounted next to a swimming pool 12. In the situation of figure 1 the swimming pool cover 1 is partially rolled up on a roll 13, so that the swimming pool 12 is partially covered in this situation.

It goes without saying that the swimming pool cover 1 is fully rolled up when the swimming pool 12 is in use and it can be fully unrolled in order to cover the swimming pool 12.

The part of the swimming pool cover 1 that is unrolled floats on the water in the swimming pool 12, because the slats 2 have significant buoyancy due to the closed chambers 10 that are filled with air.

In the unrolled situation and when rolling up and unrolling, the slats of course come into contact with the water of the swimming pool 12.

On top of flat parts of the slats 2 and especially on top of hollow parts of the slats 2, such as on top of the curved bottom wall 6 of the female connecting part 11, in the part of the slat that is designated by 14 in figure 2, this water can stay there for a long time. Rainwater can also get onto these parts of the slats 2.

This water heats up very quickly due to solar heat so that good conditions for the rapid development of microorganisms are inevitable.

Thanks to the presence of DCOIT in the walls 5,6,7,8 of the slats 2 however, no or only very limited growth of bacteria, mould, algae and other organisms in the form of a biofilm or otherwise, can take place on the surfaces of the slats, thus on the walls of the slats 2. This applies to both the walls in the slats that are closed from the outside air, and on the walls that are open to the outside air . This means that the swimming pool cover 1 does not discolour, or much less so than traditional swimming pool covers, and no large scale sources of contamination by microorganisms are in contact with the swimming pool water, so that the general hygienic condition of the swimming pool 12 is improved.

It goes without saying that the swimming pool cover, in addition to the components mentioned above _y comprises a large number of other components such as shafts, bearings, beams and partitions to separate the roll of slats from the swimming pool when this roll is mounted below water level.

These components are also sensitive to some extent, depending on the precise embodiment, to growth and can thus also be made growth-resistant with DCOIT.

In the above embodiment all walls are growth-resistant because the material from which the slat profile is manufactured has a growth-resistant agent in it.

However, it can also be chosen to make a number of walls growth-resistant, i.e. the walls that run the greatest risk of undesired growth, i.e. the walls on which or against which small quantities of stagnant water can accumulate.

Alternatively to the above, walls of slat profiles and slats can also be made growth-resistant by providing them with a surface layer, for example a coating with a growth- resistant substance therein. It goes without saying that aside from DCOIT, other substances with an activity against algae and/or mould and/or bacteria can also be used. A variety of such substances are available commercially. An optimum concentration can be easily determined by experiment.

The present invention is by no means limited to the embodiment described as an example and shown in the drawings, but a slat profile 3, slat 2 and swimming pool cover 1 according to the invention can be realised in all kinds of forms and dimensions, without departing from the scope of the invention.