Field of the invention

[0001] The present invention relates to a linoleum-based surface covering and to a method to produce such a surface covering .

Prior art and related technical background

[0002] Surface coverings, particularly linoleum surface coverings, are widely used to decorate buildings or houses surfaces, and they are generally in the form of rolls, but also in the form of tiles as there are easier to install in comparison to rolls.

[0003] Such surface covering tiles present a good dimensional stability, and only slight dimensional changes after being laid on the surface to cover, and generally complies with the requirements of the norm EN 548 when tested according to EN 669.

[0004] Linoleum surface coverings are well known coverings, made by calendering of a linoleum paste on a backing made of jute, the linoleum paste generally comprising ground cork and/or wood flour, and a linoleum cement comprising a vegetable oil, generally oxidised linseed oil, and rosin. The linoleum paste may also comprise additives such as mineral fillers and/or pigments.

[0005] However, linoleum surface coverings present the drawback of having poor dimensional stability when used as tiles . [0006] To address this issue, in the standard production of linoleum tiles, it is possible to replace the jute backing by a polyester backing, onto which is calendered the linoleum paste. However, this solution presents several drawbacks. One of the drawbacks is that it implies a fabrication process adapted to the polyester backing. Another drawback is that, as the thickness of the polyester backing is lower than that of traditional jute backing, it also requires a higher amount of linoleum paste being deposited onto the backing in order to achieve the same nominal total thickness, e.g. 2.5 mm, increasing therefore the curing time, and therefore the process time. Hence, the overall process costs are higher. Another drawback is that it is necessary to have, in addition to the stock for rolls, a stock for tiles or, as an alternative, to manage tiles as special no stock product.

Aims of the invention

[0007] The present invention aims to provide a linoleum- based surface covering and a method to produce such a surface covering that do not have the drawbacks of the prior art.

[0008] The invention aims to provide, in particular a linoleum-based surface covering easy to implement with preserved dimensional stability.

[0009] The invention aims to provide a process enabling to transform a conventional linoleum surface covering into a dimensionally stable linoleum surface covering.

Summary of the invention

[0010] The present invention relates to a linoleum-based multilayer surface covering comprising a linoleum-based layer and a first and second backing layers, said first backing layer being a jute layer facing said linoleum-based layer, said second backing layer being a polymer-based layer facing said jute layer .

[0011] According to particular embodiments, the linoleum- based multilayer surface covering may comprise one, or a combination, of any of the following characteristics:

- the polymer-based layer is a PVC-based layer, a polypropylene- based layer or a polyester-based layer,

- the polymer-based layer is a polylactic acid-based layer,

- the polymer-based layer is a woven fabric, a non-woven layer, or a layer comprising woven and non-woven parts,

the polymer-based layer comprises fibres comprising a polyester core and a polyolefin and/or polyamide coating,

- the linoleum surface covering further comprises a urethane and/or acrylic based top layer,

- the linoleum surface covering is in the form of tiles,

- the linoleum surface covering is a floor covering.

[0012] The invention relates also to a method to produce a linoleum-based multilayer surface covering according to the invention, said method comprising the step of producing at least one linoleum paste, providing a jute backing, calendering said linoleum paste on said jute backing, curing said linoleum paste on said jute backing, and gluing a polymer-based layer on the jute backing.

[0013] According to particular embodiments, the method according to the invention may comprise one, or a combination, of any of the following characteristics:

- the method further comprises the step of producing several linoleum pastes of different colours, producing crumbles from said linoleum pastes of different colours, calendering said crumbles on one side of said jute backing (3) , curing said crumbles on said jute backing,

- the polymer-based layer is a PVC-based layer, a polypropylene- based layer or a polyester-based layer, - the polymer-based layer is a woven fabric, a non-woven layer, or a layer comprising woven and non-woven parts,

- the step of gluing is performed by using an hotmelt adhesive, a spray glue, both sides adhesive tape, or buttered glue,

- the methods further comprise the step of applying a finishing top layer,

- the method further comprise the step of cutting the linoleum surface covering into tiles .

Short description of the drawings

[0014] Figure 1 represents schematically the linoleum surface covering according to the invention.

[0015] Figure 2 is a flow chart diagram of a preferred embodiment of the method to produce the linoleum surface covering according to the present invention.

[0016] Figure 3 represents schematically a preferred embodiment of the process of the invention.

Detailed description of the invention

[0017] The linoleum-based surface covering 1 according to the present invention comprises a linoleum-based layer 2, calendered on a jute backing 3, and a polymer-based layer 4 on said jute backing (fig.l) .

[0018] The polyester-based layer 4 may be a woven and/or non woven layer. It may be made of a woven fabric, a non-woven layer, or may comprise both woven and non-woven parts.

[0019] The polyester-based layer 4 may cover the overall jute backing 3 or only parts of said jute backing 3.

[0020] Preferably, the polymer-based layer 4 comprise fibres made of a polymer, or a combination of fibres made of a different polymers. For example, the fibres may comprise a polyester core, and a polyolefin and/or polyamide coating. [0021] Preferably, the polymer-based layer 4 comprise fibres mechanically, thermally or chemically, bonded together. More preferably, the fibres are at least partially thermally bonded together.

[0022] The term "fibres" should be understood as fibres as such, but also as fibres spun into filaments or threads or mixtures thereof.

[0023] The polymer-based layer 4 is either a PVC-based layer, a polypropylene-based layer or a polyester-based layer. Preferably, the polyester-based layer is a polylactic acid-based layer .

[0024] In a preferred embodiment, the polymer-based layer

4 is a woven polypropylene layer, such as for example Propex Action Bac ^® .

[0025] In another preferred embodiment, the polymer-based layer 4 is a non-woven biopolymer-based layer, such as for example polylactic acid-based layer.

[0026] In another preferred embodiment, the polymer-based layer 4 is a non-woven polyester acid-based layer.

[0027] In another preferred embodiment, the polymer-based layer 4 is a woven PVC-based layer comprising glass fibres.

[0028] In another preferred embodiment, the polymer-based layer 4 is a non-woven polyester-based layer and comprises thermally bonded continuous bi-component filaments having a PET core and a PA-6 skin. It is for example Colback SF 75 from Colbond bv, having a thickness of around 0.5 mm and a weight of around 75 g/m ² .

[0029] The jute baking 3 is any suitable backing made of jute. Preferably, the backing 3 has a thickness of between 0.55 and 0.7 mm and a weight of between 230 and 275 g/m ² .

[0030] The linoleum-based layer 2 is a layer comprising any suitable linoleum paste. [0031] The linoleum-based surface covering according to the present invention may also comprises a finishing top layer, preferably made of urethane and/or acrylic formulations.

[0032] The process to produce the linoleum-based surface covering according to the present invention comprises the steps of producing a linoleum paste, calendering the linoleum paste on a jute backing 3, curing the linoleum paste on the jute backing 3, and gluing a woven and/or non woven polymer-based layer 4 onto the opposite side of the jute backing 3.

[0033] In the process according to the invention, the polymer-based layer 4 is either a PVC-based layer, a polypropylene-based layer or a polyester-based layer. Preferably, the polyester-based layer is a polylactic acid-based layer .

[0034] The polymer-based layer 4 may be glued continuously or non-continuously onto the jute backing 3.

[0035] The linoleum paste is produced by mixing the linoleum cement to cork and wood flour, pigments, such as for example T1O ₂ , and fillers, such as for example CaCC>3.

[0036] For non-uniform colours, the process may further comprises a step of producing crumbles from linoleum pastes of different colours (fig.2) . The crumbles are thereafter laminated and calendered on the jute backing 3.

[0037] The process is implemented on any suitable device, preferably on an AUMA press (i.e. rotary press), with a contact pressure of between 100 and 180 bar between the cylinder and the steel tape and with a temperature of the cylinder of between 130 and 180°C, the line speed being between 2 and 7m /min.

[0038] For the embodiment wherein linoleum-based surface covering 1 comprises a PLA-based layer, the contact pressure is set around 100 bar, the temperature of the cylinder is around 92°C, and the line speed is around 7m /min. [0039] The process may comprise a step of applying a finishing top layer.

[0040] The process may comprise a step of cutting the linoleum surface covering 1 into tiles of any suitable dimension .

[0041] In a preferred embodiment, the step of gluing of the polymer-based woven and/or non-woven layer 4 onto the jute backing 3 is performed on a conventional linoleum-based surface covering produced in a prior process, possibly wound on rolls (fig. 3) . Therefore, the gluing step allows transforming a conventional linoleum surface covering, from existing stock linoleum rolls, into a dimensionally stable linoleum surface covering .

[0042] If a customer places an order for a linoleum surface covering according to the invention, said linoleum covering is directly processed and a woven and/or non woven polymer-based layer 4 is glued continuously or not-continuously on the jute backing 3 before being cut into tiles and packaged. If no customer's order is pending, the linoleum surface covering is produced without the polymer-based layer 4 and is wound on rolls, packaged and stored. On receipt of an order, one or several packaged rolls are taken from stock, unwrapped and preferably joined together in order to obtain a single big roll, and the polymer-based layer 4 is then glued onto the jute backing 3 before being cut and packed.

[0043] The gluing step is preferably performed before the linoleum surface covering being cut into tiles.

[0044] The gluing step is performed by any suitable method, using any suitable glue or adhesive, and using any suitable apparatus, as for example a rotary press.

[0045] The glue used is preferably selected from hotmelt adhesives, spray glue, both sides adhesive tape, buttered glue. [0046] Preferably, the glue comprises polyurethane polymers, or polyamide copolymers.

[0047] Preferably, the glue used is a composition from

Caplast Kunststoffverarbeitungs GmbH, comprising a polyolefin copolymer, having a melting temperature of between 90 to 105°C and a weight of around 55 g/m ² .

[0048] Preferably, for the embodiment wherein the linoleum-based surface covering comprises a PLA-based layer, the hotmelt used is an adhesive film of around 50 g/m ² weight and having a thickness of around 0.26 mm.

[0049] The process according to the invention enable to produce a linoleum surface covering with reduced curing time, and with reduced manufacturing costs as the thickness of linoleum paste in the final product is reduced for a same nominal thickness of the final product in comparison to a linoleum surface coverings according to the prior art .

[0050] Furthermore, the main advantage of the process according to the invention is that it is fully compatible with the traditional process to produce a jute-backed linoleum product and can thus be implemented to traditional manufacturing and existing equipments or apparatus, without substantive alterations in the installations or their operation.

[0051] The dimensional stability of a prior art linoleum surface covering and of the linoleum-based surface covering according to the present invention is assessed according to EN 669.

[0052] The prior art linoleum surface covering comprises a conventional linoleum paste calendered onto a polyester backing having a thickness of around 0.22 mm and a weight of around 97g/m ² .

[0053] The linoleum-based surface covering according to the present invention comprises the same conventional linoleum paste as the prior art linoleum surface covering, and comprises a jute fabric having a thickness of 0.62 mm and a weight of around 260 g/m ² and a non-woven polyester layer having a thickness of around 0.5 mm and a weight of around 75 g/m ² (Colback SF 75 from Colbond bv) . The linoleum surface covering is produced on an AUMA press with a contact pressure between cylinder and the steel tape of 150 bars, a temperature of cylinders of around 160°C, and a line speed of around 3m/min. the adhesive used to glue the polyester layer on the opposite side of the jute-backing is polyolefin copolymer-based composition having a melting temperature of around 97°C and a weight of around 55 g/m ² (Caplast Kunststoffverarbeitungs GmbH) .

[0054] For the comparison test according to EN 669, the linoleum tiles are first conditioned at (23 ± 2) °C and (50 ± 5) % of relative humidity (r.h.) for at least 24 h, then at (23 ± 2) °C and (80 ± 5) % relative humidity for (24 ± 0.5) h, and dimensions are measured before and after (within 10 min.) exposure at (80 ± 5) % r.h. The norm EN 548 establishes that dimensional variation caused by changes of atmospheric humidity must be < 0.1%.

Table 1: dimensional stability.

[0055] As presented in table 1, the linoleum surface covering according to the present invention presents a dimensional stability in compliance with the requirements of EN 548.