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Title:
LAMINATED STEEL PRODUCT
Document Type and Number:
WIPO Patent Application WO/2020/182538
Kind Code:
A1
Abstract:
Laminated steel product for building and construction applications, comprising a hot dip galvanised zinc alloy coated steel strip having a thickness between 0,4 and 1,5 mm and a thermoplastic polymer layer laminated on one or both sides of the zinc alloy coated steel strip, wherein the laminated steel product is provided with a corrosion inhibiting and adhesive layer between the zinc alloy coated steel strip and the thermoplastic polymer layer on one or both sides of the zinc alloy coated steel strip.

Inventors:
BOELEN BEREND (NL)
VAN VLIET BART (NL)
HOEBEN JIM WILHELMUS (NL)
Application Number:
PCT/EP2020/055547
Publication Date:
September 17, 2020
Filing Date:
March 03, 2020
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
TATA STEEL IJMUIDEN BV (NL)
International Classes:
B32B7/12; B32B15/082; B32B15/085; B32B15/088; B32B15/09; B32B15/18; B32B27/30; B32B27/32; B32B27/34; B32B27/36
Domestic Patent References:
WO2013083292A12013-06-13
WO2014114370A12014-07-31
WO2012146654A12012-11-01
WO2017174345A12017-10-12
Foreign References:
EP0067060A11982-12-15
KR101142766B12012-05-18
EP2872261B12016-09-14
CA2916430A12014-07-31
US9186875B12015-11-17
Attorney, Agent or Firm:
GROUP INTELLECTUAL PROPERTY SERVICES (NL)
Download PDF:
Claims:
CLAIMS

1. Laminated steel product (1) for building and construction applications, comprising a hot dip galvanised zinc alloy coated steel strip (2) having a thickness between 0,4 and 1 ,5 mm and a thermoplastic polymer layer (3) laminated on one or both sides of the zinc alloy coated steel strip (2), characterised in that the laminated steel product (1) is provided with a corrosion inhibiting and adhesive layer (4) between the zinc alloy coated steel strip (2) and the thermoplastic polymer layer (3) on one or both sides of the zinc alloy coated steel strip (2).

2. Laminated steel product (1) according to claim 1 , characterised in that the thermoplastic polymer layer (3) is a machine direction oriented film.

3. Laminated steel product (1) according to claims 1 or 2, characterised in that a primer layer (5) is provided on top of the corrosion inhibiting and adhesive layer (4) on one or both sides of the zinc alloy coated steel strip (2).

4. Laminated steel product (1) according to anyone of the claims 1 - 3, characterised in that a top-coat layer (6) is provided on top of the thermoplastic polymer layer (3) on one or both sides of the zinc alloy coated steel strip (2).

5. Laminated steel product (1) according to anyone of the claims 1 - 4, characterised in that a paint layer (7) is provided on one or both sides of the zinc alloy coated steel strip (2).

6. Laminated steel product (1) according to anyone of claims 1 - 5, characterised in that a back-coat layer (8) is provided on the intended back side of the laminated steel product (1).

7. Laminated steel product (1) according to anyone of the claims 1 - 6, characterised in that one or more further layers (9) are provided on one or both sides of the zinc alloy coated steel strip (2).

8. Laminated steel product (1) according to anyone of claims 1 - 7, characterised in that a zinc alloy coating on the zinc alloy coated steel strip (2) comprises at least 95% of zinc. 9. Laminated steel product (1) according to anyone of claims 1 - 8, characterised in that the zinc alloy coating of the zinc alloy coated steel strip (2) comprises 0,3 - 2,3 % aluminium and 0,6 - 2,3 % magnesium, with the remainder being zinc, and unavoidable impurities.

10. Laminated steel product (1) according anyone of the claims 1 - 9, characterised in that the zinc alloy coating of the zinc alloy coated steel strip (2) comprises up to 0,5 % aluminium and more than 99,5 % zinc, and unavoidable impurities.

11. Laminated steel product (1) according to anyone of the claims 1 - 10, characterised in that the thermoplastic polymer layer (3) is a layer of polyethylene terephthalate or polypropylene or polyamide or polyethylene or polyvinylchloride or polytetrafluorethylene or polyethylene 2,5- fu rand icarboxy late or polyvinylidene fluoride or a combination thereof.

12. Laminated steel product (1) according to anyone of claims 1 - 11 , characterised in that the zinc alloy coated steel strip (2) is between 1 ,0 and 1 ,5 mm thick.

13. Method for producing a laminated steel product (1) for building and construction applications, comprising providing a hot dip galvanised zinc alloy coated steel strip (2) having a thickness between 0,4 and 1 ,5 mm and laminating a thermoplastic polymer layer (3) on one or both sides of the zinc alloy coated steel strip (2), characterised in that before applying the thermoplastic polymer layer (3) to one or both sides of the zinc alloy coated steel strip (2), the zinc alloy coated steel strip (2) is provided with a corrosion inhibiting and adhesive layer (4).

14. Method for producing a laminated steel product (1) according to claim 13, characterised in that the thermoplastic polymer layer (3) is a machine direction oriented film.

15. Method for producing a laminated steel product (1) according to claim 13 or 14, characterised in that a zinc alloy coating on the zinc alloy coated steel strip (2) comprises at least 95% of zinc.

Description:
LAMINATED STEEL PRODUCT

The invention relates to a laminated steel product for building and construction applications, comprising a hot dip galvanised zinc alloy coated steel strip having a thickness between 0,4 and 1 ,5 mm and a thermoplastic polymer layer laminated on one or both sides of the zinc alloy coated steel strip. The invention is also related to a method for producing such a laminated steel product.

Such a laminated steel product is known from the prior art. WO 2014/114370 describes a laminated steel product for cans. These products use a very thin zinc coated steel strip, between 0,1 and 0,5 mm thick, which is suitable for making packaging materials. Further, the surface of the zinc coated steel is temper rolled in the rolling department to improve the adhesion of the polymer layer to the zinc coated steel strip.

WO 2012/146654 describes the adhesion of the polymer layer to a metal strip by first melting the polymer granules in an extruder and passing the molten polymer through one or more dies or calendars to form the polymer film. After that the laminating step takes place. This process is also developed for packaging purposes and therefore uses very thin metal strips in the order of 0,1 to 0,3 mm.

US 9186875 discloses a process for applying a polyester onto a metal strip which is generally useful for can making. Described is also the application in building and construction products, but the skilled person is left in the dark when it comes down to the specific measures that need to be taken to live up to the specifications for this purpose. To promote the adhesion of the polymer film the metal strip a surface energy treatment is applied to increase the surface energy by heating, ozone treatment, ultra-high frequency electrical discharge, UV or laser bombardment.

WO 2017/174345 discloses a process aimed at the production of a laminated steel product for packaging, like cans or containers. The metal strip is laminated on both sides with a thermoplastic polymer. The polymers described are suitable for can making.

However, these known laminated metal products are not suitable for building and construction applications. The quest for corrosion resistant and durable building and construction materials made from metal and particularly steel, is a long and ongoing one. Building and construction application of steel dictates a special set of parameters compared to the packaging of food materials. The circumstances for the building and construction materials made from steel can be quite hostile, as wind, rain, sun, freezing cold and blazing heat all have a big influence on the durability of the steel products. Further, sea salt in coastal areas is a major contributor to corrosion. And in winter time, salt used to keep the traffic going in some Western European countries also has a deteriorating effect on the laminated steel product which are usually applied to the outside of a building. On top of that, detergents used to keep the appealable appearance that was in the mind of the architect when his design was created, can have a negative influence on the laminated steel product.

Unfortunately, the packaging materials described in the state of the art are simply too thin and not strong enough to be used for building and construction applications. Steel products for building and construction purposes usually are made of thick steel (0,4 to 1 ,5 mm) which is then painted to provide the necessary protection against corrosion and other influences.

Usually the paint is applied using volatile organic chemicals. These chemicals however are now considered not to be beneficial to our ecosystem and the paints have relatively bad adhesive properties on zinc alloy coated steels. When the paint is damaged, this has a negative influence on the outlook and the mechanical properties of the laminated steel. Also line speeds for these painting processes are relatively low and therefore the painted products are more expensive to produce. Further, practice has shown that painted steel products can be damaged rather easily during the forming process which then decreases the corrosion protection and the life of the product.

For building and construction applications zinc alloy coated steel, also called galvanised

steel is usually used as a base material. This material is usually not used as packaging steel. Steel for packaging purposes mostly comprises tin coated steel or chromium coated steel. Zinc alloy coated steel has far worse adhesive properties than tin coated steels or chromium coated steels, setting yet another challenge for building and construction applications. The adhesion of a polymer to this zinc alloy coated steel for building and construction applications is a major challenge which so far only could only properly be solved by using a specially formulated and expensive adhesive which must be applied in a relatively thick layer of several micro meters on the zinc alloy coated steel. It is clear to the skilled person that zinc alloy coating in this context also comprises zinc coating without alloys.

The current invention relates to solve these problems of the prior art and provide a laminated steel product that is strong, sustainable, lasts for decades and can withstand all the weather elements. Furthermore, a material for building and construction applications is provided which can be produced with higher line speeds, has better forming properties and can be produces without using volatile organic chemicals.

Accordingly the laminated steel product is provided with a corrosion inhibiting and adhesive layer between the zinc alloy coated steel strip and the thermoplastic polymer layer on one or both sides of the zinc alloy coated steel strip. This corrosion inhibiting and adhesive layer can be applied to a thickness in the order of 1 to 30 nanometer, preferably between 5 and 20 nanometer and preferably 10 nanometer. This layer is a lot thinner than the previously applied adhesive layer, so less material is needed and therefore this is more environmentally friendly. A suitable corrosion inhibiting and adhesive layer for the zinc alloy coated steel strip is made from Bonderite M-NT 10456 CT1080 RWE, which is available from Henkel. This product is sold as a corrosion inhibiting material, but the inventors found that this material has also surprisingly good adhesion properties. Further it contains no volatile organic chemicals as it is water based. Therefore, no extra adhesive or any other layer is needed to make a durable laminated steel product for building and construction applications. Thus, with this invention, a laminated steel product is obtained for building and construction applications, able to resist the influence of the weather and be sustainable for several decades. Naturally this is also better from an environmental point of view as replacement is not needed for a longer period of time.

The obtained product has very beneficial properties for use in outdoor building and construction building applications such as wall cladding and roofing systems. But also indoor uses are possible, as the requirements for indoor use are less strict. Another benefit is that the thermoplastic polymer layer can be chosen to a specific thickness and material to improve the corrosion resistance, but also the aesthetic possibilities are widened as the thermoplastic polymer films can come in all colours of the rainbow and could be applied with a design already printed on or in the thermoplastic polymer film saving time during the building process. Further, no curing on the coil needs to take place like is the case with painted steel products and there are no fluid effects (e.g. ribbing) that determine the application speed, like in the painting process. So the speed of producing these products is also considerably increased. Another benefit is that the polymer film has better elastic properties than paint, making the laminated steel product more sustainable than the painted versions of the prior art.

Preferably the thermoplastic polymer layer is a machine direction oriented (MDO) film. This is a film that is oriented in a uniaxial manner and has improved stiffness and barrier properties.

The formed laminated steel product could be also used for other indoor applications, such as white and brown goods, furniture steels and sandwich panels without changing the basic concept.

It may be preferable that a primer layer is provided on top of the corrosion inhibiting and adhesive layer on one or both sides of the zinc alloy coated steel strip. This is beneficial as it gives an even better corrosion protection to the product, further increasing the durability. Another benefit is that the formation properties further improve, giving the architect or designer even wider technical possibilities for an aesthetically pleasing design, which is a rare phenomenon these days. The primers that have shown to be beneficial are polyester or polyester-polyurethane (for example CP48, available from Akzo Nobel, formerly BASF) based. Also beneficial is that a primer masks the metal“colour”, so the options for design improve as well with the application of a primer layer.

To promote the achievements of the invention it is preferred that a top-coat layer is provided on top of the thermoplastic polymer layer on one or both sides of the zinc alloy coated steel strip. This will protect all the other layers described earlier and improve the corrosion resistance and the appearance in a durable manner. To this layer colours could be added, but also a see-through top-coating could be applied, depending on the specific technical requirements.

Preferably a paint layer is provided on one or both sides of the zinc alloy coated steel strip. It may be clear that adding a paint layer will further improve the corrosion inhibition properties. However, it also brings more options for the architects and designers, such as adding appealing colours or patterns. Another preferred option is the addition of a light sensitive paint layer that glows in the dark adding to the well being and comfort of people during the night time hours and create a more safe environment. This option would be very beneficial as it will need less energy consumption, since less electric light is needed to light the buildings at night.

Preferably a back-coat layer is provided on the intended back side of the laminated steel product. The intended back side of the laminated steel product is usually protected more against all the influences mentioned earlier since it is not facing outward to the hostile environment. Therefore, there may be less need to apply a layer having the corrosion resistance properties compared to the layers applied on the front side. A back-coat layer can be chosen according to the specifications needed for the specific application adding to the flexibility of the possibilities with the laminated steel product. This layer may also be a thermoplastic polymer layer.

Preferably one or more further layers are provided on one or both sides of the zinc alloy coated steel strip. Layers could be added that have special properties regarding for example isolation or light reflection. A layer with light reflecting flakes is imaginable which gives the laminated steel product a distinctive appearance which could then act as a landmark for people on the streets, but also for airline pilots as a striking beacon on the ground. Also this further layer could for example have a mirror effect, for instance in silver, or even gold. The latter could be the preferred effect for people that have more money than taste. Another option is that it could also be a layer that reacts to the level of (day)light present and/or changes colour when desired.

Preferably a zinc alloy coating on the zinc alloy coated steel comprises at least 95% of zinc. This has the benefit of the laminated steel product being protected against corrosion and providing a good base for the laminated steel product.

Preferably the zinc alloy coating of the zinc alloy coated steel strip comprises 0,3 - 2,3 % aluminium and 0,6 - 2,3 % magnesium, with the remainder being zinc, and unavoidable impurities. A suitable zinc alloy coating for the steel product is MagiZinc ®, giving excellent results and which is a product of Tata Steel which is mainly used in automotive steels. Automotive steels also need to be protected against corrosion as motorcars and other vehicles are exposed to the elements of all weather conditions mentioned earlier and salt on the roads in winter time. The zinc alloy coating comprises 0,3 - 4,0 % magnesium, 0,3 - 6,0 % aluminium, the rest being zinc, and unavoidable impurities. Preferably the zinc alloy coating comprises 0,3 - 2,3 % magnesium, 0,6 - 2,3 % aluminium, the rest being zinc, and unavoidable impurities. More preferably the zinc alloy coating comprises 1 ,6 - 2,3 % magnesium, 1 ,6 - 2,3 % aluminium, the rest being zinc, and unavoidable impurities.

Preferably the zinc alloy coating of the zinc alloy coated steel strip comprises up to 0,5 % aluminium and more than 99,5 % zinc, and unavoidable impurities.

Preferably the thermoplastic polymer layer is a layer of polyethylene terephthalate or polypropylene or polyamide or polyethylene or polyvinylchloride or polytetrafluorethylene or polyethylene 2,5-furandicarboxylate or polyvinylidene fluoride or a combination thereof. These polymers have shown the best results in these applications with respect to corrosion protection and aesthetical appeal. The polymer chosen is an optional one which can be chosen according to the specific application. Also combinations are possible, even in layers having different thicknesses.

Preferably the zinc alloy coated steel strip is between 1 ,0 and 1 ,5 mm thick. It may be clear that the zinc alloy coated steel strip has the best available properties for the building and construction applications of this invention, as explained earlier. The thickness is needed as it is used as a building or construction material for bringing the necessary strength. Preferably the zinc alloy coated steep strip has a minimum thickness of 0,6 mm. More preferably the zinc alloy coated steep strip has a minimum thickness of 0,8 mm. Even more preferably the zinc alloy coated steep strip has a minimum thickness of 1 ,0 mm. Preferably the zinc alloy coated steep strip has a maximum thickness of 1 ,3 mm. More preferably the zinc alloy coated steep strip has a maximum thickness of 1 ,4 mm. Even more preferably the zinc alloy coated steep strip has a maximum thickness of 1 ,5 mm.

In the method for making a laminated steel product for building and construction applications, the method comprises providing a hot dip galvanised zinc alloy coated steel strip having a thickness between 0,4 and 1 ,5 mm and laminating a thermoplastic polymer layer on one or both sides of the zinc alloy coated steel strip. Before applying the thermoplastic polymer layer to one or both sides of the zinc alloy coated steel strip, the zinc alloy coated steel strip is provided with a corrosion inhibiting and adhesive layer. Preferably the thermoplastic polymer layer is produced as a machine direction oriented (MDO) film. This is a film that is oriented in a uniaxial manner and has improved stiffness and barrier properties.

The invention will hereinafter be further elucidated with reference to the drawing of an exemplary embodiment of an apparatus operating according the method of the invention that is not limiting as to the appended claims.

In the drawing:

- figure 1 shows the product according to the invention in its most basic form;

- figure 2 shows the product with a primer layer;

- figure 3 shows the product with a top-coat;

- figure 4 shows the product with a paint layer;

- figure 5 shows the product with symmetrical layering;

- figure 6 shows the product with a back-coat layer; and

- figure 7 shows the product with a further layer.

Whenever in the figures the same reference numerals are applied, these numerals refer to the same parts.

Figure 1 shows the product according to the invention in its most basic form. A laminated steel product (1), which is adjusted for building and construction applications, comprises a hot dip galvanised zinc alloy coated steel strip (2) having a thickness between 0,4 and 1 ,5 mm and a thermoplastic polymer layer (3) laminated on, in this example, one side of the zinc alloy coated steel strip (2). Naturally the thermoplastic polymer layer (3) could also be applied on both sides of the zinc alloy coated steel strip (2). Between the zinc alloy coated steel strip (2) and the thermoplastic polymer layer (3) a corrosion inhibiting and adhesive layer (4) is provided. The corrosion inhibiting and adhesive layer (4) has both corrosion inhibiting properties and surprisingly good adhesive properties. Therefore a separate adhesive is not necessary. This corrosion inhibiting and adhesive layer (4) could also be applied on both sides of the zinc alloy coated steel strip (2).

Figure 2 shows the product with a primer layer (5). In this example it is added on top of the thermoplastic polymer layer (3), but could also be added on top of the zinc alloy coated steel strip (2) or on top of the corrosion inhibiting and adhesive layer (4). The primer layer (5) could be provided on one or both sides of the laminated steel product (1). Figure 3 shows the product with a top-coat layer (6) on top of the one or more thermoplastic polymer layers (3). In this example it is provided on top of the thermoplastic polymer layer (3) on one side, but could also be added to the thermoplastic polymer layer (3) and any other layer, like the primer layer (5), paint layer (7), back-coat layer (8) and further layer (9) on one or on both sides of the laminated steel product (1).

Figure 4 shows the product with a paint layer (7). In this example it is provided on top of the top-coat layer (6) on one side, but could also be added on top of any other layer present and on one or both sides of the laminated steel product (1).

Figure 5 shows the product with symmetrical layering. In this case the laminated steel product comprises the hot dip galvanised zinc alloy coated steel strip (2) which has a corrosion inhibiting and adhesive layer (4) on both sides of the zinc alloy coated steel strip (2). On top of the corrosion inhibiting and adhesive layer (4) the thermoplastic polymer layer (3) is added on both sides of the zinc alloy coated steel strip (2). Naturally all other configurations in these examples / figures could also be symmetrical, so on both sides of the zinc alloy coated steel strip (2). It is also imaginable, and therefore needs no further elaboration, that both sides of the laminated steel product (1) could be symmetrical, meaning layering on both sides of the zinc alloy coated steel strip (2) are the same. But it could also by asymmetrical, meaning the layers on each side are different. This all depends on the specific application of the laminated steel product and the specifications set therefore.

Figure 6 shows the product with an back-coat layer (8), In this example this back-coat layer (8) is provided on top of the corrosion inhibiting and adhesive layer (4), but could also be provided on top on the zinc alloy coated steel strip (2). Further this example shows the optional primer layer (5) on top of the thermoplastic polymer layer (3). Naturally other configurations are possible as the skilled person will understand.

Figure 7 shows the product with a further layer (9). In this example the further layer (9) is provided on one side of the zinc alloy coated steel strip (2) but could also be present on both sides. The figure shows the further layer (9) on top of the optional primer layer (5). But this further layer (9) could be on top of other layers as well, like the corrosion inhibiting and adhesive layer (4) or the thermoplastic polymer layer (3).

Although the invention has been discussed in the foregoing with reference to exemplary embodiments of the invention, the invention is not restricted to these particular embodiments which can be varied in many ways without departing from the invention. The discussed exemplary embodiments shall therefore not be used to construe the appended claims strictly in accordance therewith. On the contrary, the embodiments are merely intended to explain the wording of the appended claims, without intent to limit the claims to these exemplary embodiments. The scope of protection of the invention shall therefore be construed in accordance with the appended claims only, wherein a possible ambiguity in the wording of the claims shall be resolved using these exemplary embodiments.