A wallcover and a method of producing the same

Abstract

According to an example aspect of the present invention, there is provided a wallcover comprising a nonwoven substrate layer with a backing layer and an intermediate layer, disposed on one side of the backing layer, and a coating layer disposed on the intermediate layer. The backing layer comprises a mixture of cellulose fibers and coarse synthetic fibers. The invention also relates to a method of producing wall coverings. The invention provides environmentally friendly wallcovers, which may be produced in a single process phase without multiple manufacturing steps.

Description

A WALLCOVER AND A METHOD OF PRODUCING THE SAMEFIELD

[0001] The present invention relates to wall coverings and more particularly to wall coverings intended for use in areas of high traffic. In particular, the present invention concerns a wallcover comprising a nonwoven substrate layer with a backing layer and an intermediate layer, disposed on one side of the backing layer, and a coating layer disposed on the intermediate layer. The invention also relates to a method of producing wall coverings. The invention provides environmentally friendly wallcovers, which may be produced in a single process phase without multiple manufacturing steps.BACKGROUND

[0002] Conventionally, the construction of wall coverings involves a two-step process to produce a three-layer construction. A three-layer construction comprises a substrate or backing layer, an intermediate layer and a decorative layer. The substrate or backing layer is typically comprised of a thin paper material, a woven fabric, or some other type of nonwoven material. The substrate layer is laminated to the intermediate layer, which typically comprises vinyl or vinyl alternative. The intermediate layer comprising vinyl or vinyl alternative provides strength and structure to the final product. It also supplies the background color and provides additional flexibility for embossing. The decorative layer is applied on top of the intermediate layer and may be produced using numerous types of methods such as rotogravure, flexography, digital printing, and screen printing. The decorative layer typically comprises inks and optional protective coatings.

[0003] The conventional production process involves the application of a decorative layer on the intermediate vinyl / vinyl alternative layer followed by lamination of the intermediate layer on the backing layer. The conventional process and wallcovers produced by the same have various disadvantages that include the requirement of an extra lamination step that increases operational and material cost, and the inclusion of a less environment- friendly vinyl / vinyl-alternative layer in the wall covering.

[0004] There exist nationally recognized quality standards for wall coverings for institutional and commercial use in several countries. In the United States, differentphysical requirements and test methods are set for wallcoverings classified as Type I (light duty, intended for use in areas of low wear, such as residential use), Type II (medium duty, hotels etc.) and Type III (heavy duty, e.g. hospitals). The requirements and test methods are disclosed in specifications W-101 (2017, for polymer coated fabric wallcoverings) and W-102 (2019, for alternative constructions other than vinyl wallcoverings) Wallcovering Association quality standards.

[0005] Prior art wallcovering materials meeting Type II requirements are generally PVC (polyvinyl chloride) coated or TPO (thermoplastic olefin) coated. Such PVC or TPO coated papers are coated offline which is time and energy expensive. Moreover, the use of PVC creates problems: the raw materials comprising PVC can emit undesirable volatile organic compounds already during production process and during use. The PVC coated papers are known to be particularly harmful during their bum, which produces additional health risks for the habitants and for the fire-fighters. While burning, PVC coated wallcover papers emit hazardous and toxic fumes, such as hydrochloric acid.

[0006] A wallcover paper coated with a plastic layer of thermoplastic olefin containing material is disclosed in US 2005 / 0014431. The plastic layer contains a TPO polymer and optionally a filler such as CaCOs or TiO2. This plastic layer is aimed at being printed / embossed. The base substrate disclosed in this document is a nonwoven web comprising natural and / or synthetic fibers, a binder (more particularly an acrylic binder) and filler (in particular clay). In one embodiment the base substrate can be a two-ply nonwoven web. It has further to be noted that TPO coated wallcover have a tendency to bum quickly or have a large fire spread when exposed to fire and are plastic-based materials which are not environmentally friendly. CN112318955 A relates to wallcovering, which comprises a bottom layer of polyester staple fibres and a surface layer comprising wood pulp fibres, the two layers being manufactured in separate process steps.

[0007] To address the issues related to the conventional process, it has now been found that wall coverings can be constructed by a single-step process with more environmentally friendly materials and by eliminating a lamination step. The invention thus discloses wallcovers, which are comprised of environmentally friendly materials and may be constructed in a single-step process and meet the quality standards set for wall coverings, in particular Type II requirements defined in W-102 Wallcovering Association quality standard.SUMMARY OF THE INVENTION

[0008] The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0009] As discussed above, it is one of the aims of the present invention to eliminate at least a part of the problem relating to the art and to provide a wallcover and a method of producing a wallcover with the above mentioned advantageous properties.

[0010] The present invention is based on the concept of using more environmentally friendly wet-laid nonwoven material as wallcovering construction material and of eliminating the vinyl / vinyl alternative intermediate layer, the wallcovers nevertheless having the required properties, such as tear strength and scrubability, to meet the Type II requirements. The method of the invention involves a single-step process where the intermediate layer and backing layer of the wall cover are formed together through hydrogen bonding and fiber interlocking, thus eliminating the need of an extra lamination step.

[0011] According to a first aspect of the present invention, there is thus provided a wallcover comprising:- a nonwoven substrate layer comprising: o a backing layer; and o an intermediate layer, disposed on one side of the backing layer; and- a coating layer disposed on the intermediate layer; wherein the backing layer comprises a mixture of cellulose fibers and of coarse synthetic fibers and wherein the coarse synthetic fibers have a linear density of at least 5 dtex. Preferably, the nonwoven substrate layer is a wet-laid nonwoven web.

[0012] According to a second aspect of the present invention, there is provided a method of producing a wallcover, wherein the method comprises the steps of:- forming an intermediate layer in a wet-laid process;- forming a backing layer in a wet-laid process;- optionally pressing the layers together;- drying the layers to obtain a contiguous two-ply nonwoven sheet;- impregnating the dried two-ply nonwoven sheet by applying a binder composition that saturates into both sides of the two-ply nonwoven sheet;- drying the binder-treated two-ply nonwoven sheet to form a nonwoven substrate layer; and- applying a coating layer on top of the intermediate layer of the obtained nonwoven substrate layer; wherein the backing layer of the two-ply nonwoven sheet comprises a mixture of cellulose fibers and coarse synthetic fibers and wherein the coarse synthetic fibers have a linear density of at least 5 dtex.According to a third aspect of the present invention, there is provided a use of a wallcover as described here-above on the surface of interior walls of a building, preferably in areas of medium wear according to W-102 Wallcovering Association quality standard.According to a fourth aspect of the present invention, there is provided a method of protecting a surface of an interior wall of a building in areas of medium wear according to W-102 Wallcover Association quality standard with a wallcover as described here-above.

[0013] Considerable advantages are obtained by the invention. First, the present wallcovers are more environmentally friendly since the use of vinyl, vinyl alternatives, olefins and adhesives is avoided. However, the wallcovers of the present invention meet Type II requirements set for wallcoverings intended for use in areas of medium wear. Thus, the invention provides Type II wallcover material, which is more environmentally friendly while complying with or exceeding the W-102 Wallcovering Association quality standard properties for Type II wallcovering.

[0014] Second, the present wallcovers may be produced in a single process phase, thus making them cheaper and faster to manufacture, compared to existing Type II wallcovering materials which require multiple steps to manufacture. The substrate layer of the present wallcover is produced without adhesives and without lamination steps.

[0015] Moreover, the present wallcovers show excellent results in burning tests compared to existing, PVC containing Type II wallcovering materials, which emit hazardous and toxic fumes during their burn. Further, the present wallcovers can be easily printed, are resistant to stain and scrubbing, and show good dimensional stability with minimum shrinkage.

[0016] Further features and advantages of the present technology will appear from the following description of some embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIGURE 1 illustrates a side view of a wallcover in accordance with at least some embodiments of the present invention, with the following reference numbers: (1) wallcover; (3) nonwoven substrate layer; (5) backing layer; (7) intermediate layer; (9) coating layer; (11) print side of the wallcover 1.EMBODIMENTS

[0018] Figure 1 illustrates a wallcover 1 according to the present invention, said wallcover 1 comprising:- a nonwoven substrate layer 3 comprising: o a backing layer 5; and o an intermediate layer 7, disposed on one side of the backing layer 5; and- a coating layer 9 disposed on the intermediate layer 7; wherein the backing layer 5 comprises a mixture of cellulose fibers and of coarse synthetic fibers and wherein the coarse synthetic fibers have a linear density of at least 5 dtex.

[0019] As used herein and in the claims, the terms “nonwoven” or “web” refer to a collection of fibers in a mass of such fibers, which are randomly interlocked, entangled and / or bound to one another so as to form a structural element.

[0020] As used herein, “synthetic fibers” refer to fibers made from fiber-forming substances including polymers synthesized from chemical compounds and modified or transformed natural polymers. Preferred, non-limiting examples of synthetic fibers include polyaramide fibers, polyamide fibers, polyester fibers, polyvinyl alcohol fibers, polypropylene fibers, glass fibers, and combinations thereof.

[0021] The synthetic fibers will have a synthetic fiber length. As used herein, “coarse synthetic fibers” have a length of at least 12 mm, preferably at least 18 mm. In some embodiments, the length of coarse synthetic fibers may be no greater than 45 mm, orno greater than 35 mm. For example, the coarse synthetic fibers may have a length in a range between 12 mm and 45 mm or between 18 mm and 35 mm.

[0022] As used herein and in the claims, “thin synthetic fibers” will have a synthetic fiber length. Preferred synthetic fiber lengths of thin synthetic fibers may be no greater than 15 mm, preferably the thin synthetic fibers have a length comprised between 5 mm and 12 mm.

[0023] The synthetic fibers may have a linear density or linear mass. The coarse synthetic fibers may have a linear density of at least 5 dtex, For example, the coarse synthetic fibers may have a linear density between 5 dtex and 10 dtex. The thin synthetic fibers may have a linear density between 1 dtex and 4 dtex, preferably between 1 and 3.5 dtex.

[0024] The backing layer 5 of nonwoven substrate layer 3 comprises a mixture of cellulose fibers and of coarse synthetic fibers. In some embodiments, the fibers in the backing layer 5 consist of cellulose fibers and coarse synthetic fibers.

[0025] In some embodiments, the backing layer 5 comprises a mixture of cellulose fibers, coarse synthetic fibers, and thin synthetic fibers. In some embodiments, the fibers in the backing layer 5 consist of cellulose fibers, coarse synthetic fibers and thin synthetic fibers.

[0026] The amount of cellulose fibers, coarse synthetic fibers and optional thin synthetic fibers may be expressed as a weight percentage based on the total weight of the fibers in the backing layer 5. In some embodiments, cellulose fibers may be present in the backing layer 5 at a level of at least 50 wt%, preferably at least 60 wt%, based on the total weight of the fibers in the backing layer 5. In some embodiments, the coarse synthetic fibers may be present in the backing layer 5 at a level of at least 5 wt%, preferably in a range of 5 to 30 wt%, more preferably in a range of 5 to 20 wt%, based on the total weight of the fibers in the backing layer 5. In some embodiments, the thin synthetic fibers may be present in the backing layer 5 at a level of 15 to 30 wt%, based on the total weight of the fibers in the backing layer 5. Strength properties of the wallcover 1 such as the tensile strength, tearing strength, and puncture resistance can be adjusted by varying the coarse synthetic fiber percentage in the backing layer 5.

[0027] In some embodiments, the fibers in the backing layer 5 may comprise from 5 to 20 wt% of coarse synthetic fibers and from 20 to 25 wt% of thin synthetic fibers, based on the total weight of the fibers in the backing layer 5, the remaining fibers comprising cellulose fibers.

[0028] Preferably, coarse synthetic fibers are selected from polyaramide fibers, polyamide fibers, polyester fibers, polyvinyl alcohol fibers, polypropylene fibers, glass fibers, and combinations thereof. When used, the thin synthetic fibers may be selected from polyaramide fibers, polyamide fibers, polyester fibers, polyvinyl alcohol fibers, polypropylene fibers, glass fibers and combinations thereof. Non-limiting examples of polyester fibers are polyalkylene terephthalates such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and the like. Non-limiting examples of polyamide fibers are nylon, e.g. nylon-t, nylon 6,6, nylon-6, 12, and the like.

[0029] In some embodiments, the backing layer 5 may further comprise additives, typically wet strength additives, dry strength additives or combinations thereof.

[0030] The backing layer 5 has a basis weight, which typically is 130 g / m2to 160 g / m2

[0031] In addition to the backing layer 5, the nonwoven substrate layer 3 of the wallcover comprises an intermediate layer 7, disposed on one side of the backing layer 5. The intermediate layer 7 typically comprises or consists essentially of cellulose fibers. Cellulose fibers may comprise bleached or unbleached hardwood pulp or softwood pulp, bleached or unbleached chemi-thermomechanical pulp from hardwood or softwood, bleached or unbleached chemical pulp from hardwood or softwood, and combinations thereof.

[0032] In some embodiments, the intermediate layer 7 comprises 0-50 wt% of softwood fibers and 50-100 wt% of hardwood fibers, based on the total weight of the fibers of the intermediate layer 7. In some embodiments, the intermediate layer 7 may comprise at most 5 wt % of softwood fibers and at least 95 wt% hardwood fibers. In some embodiments the fibers of the intermediate layer 7 consist of or consist essentially of hardwood fibers. An intermediate layer 7 comprising a high proportion of hardwood fibers has a very low porosity and thus a high smoothness.

[0033] In some embodiments, the hardwood fibers in the intermediate layer 7 comprise a blend of eucalyptus fibers and birch fibers, preferably the eucalyptus fibers are present in an amount of at least 50 wt%, based on the total weight of hardwood fibers, and the birch fibers are present in an amount of at most 50 wt%, based on the total weight of the hardwood fibers. In some embodiments, the hardwood fibers may comprise a blend of eucalyptus fibers and birch fibers, wherein the eucalyptus fibers are present in an amount of about 75 wt%, based on the total weight of the hardwood fibers, and the birch fibers are present in an amount about 25 wt%, based on the total weight of the hardwood fibers. This mixture of hardwood fibers enables to have a smooth surface intermediate layer 7 improving the deposition quality of a coating layer 9, which will also improve the printability of the wallcover 1. In particular, eucalyptus fibers are small and help in improving the smoothness of the intermediate layer 7 as well as the formation of the sheet forming this intermediate layer 7.

[0034] The intermediate layer 7 typically has a basis weight of 10 g / m2to 30 g / m2

[0035] The backing layer 5 and the intermediate layer 7, disposed on one side of the backing layer 5, are intermingled at the interface of the layers, and hydrogen bonding occurs between the layers in the dewatering and drying process, thus forming the nonwoven substrate layer 3. No adhesive layers or lamination steps are needed in order to enable the adhesion between the backing layer 5 and the intermediate layer 7 in the nonwoven substrate layer 3.

[0036] In some embodiments, the nonwoven substrate layer 3 may be impregnated with an impregnation composition. The impregnation composition may comprise a binder, fillers, and optionally additives. Typically, suitable binders are selected among styrene acrylate, acrylic, latex, ultra-low (<20 ppm) formaldehyde acrylic, and combinations thereof. In some preferred embodiments, a binder having a glass transition temperature of between -25°C and +10°C may be chosen. An impregnation composition comprising a binder having a glass transition temperature between -25°C and +10°C enables to have flexibility in the impregnated nonwoven substrate layer 3.

[0037] The fillers of the impregnation composition may be chosen among kaolin, calcium carbonate, titanium dioxide, or combination thereof. The impregnation composition may comprise additives, typically selected from pigments, antifoam agents, wetting agents, curing agents, optical brighteners and any combinations thereof.

[0038] When impregnated, the nonwoven substrate layer 3 may be impregnated with the impregnation composition in an amount of 80 g / m2to 120 g / m2.

[0039] The wallcover 1 further comprises a coating layer 9 disposed on the intermediate layer 7 of the nonwoven substrate layer 3. The coating layer 9 brings additional resistance, smoothness, and scrubability to the wallcover 1. The coating layer 9 may comprise for example acrylic resins and pigments. Typically, the acrylic resin is a hydrophobic styrene acrylic resin, which provides additional stain resistance and printability. The top side of the coating layer 9 forms a print side 11 of the wallcover 1, this print side 11 being aimed at receiving a print on it. Thus in some embodiments the print side 11 of the coating layer 9 is printed, said print side 11 being disposed on the side of the coating layer opposite to the side in contact with the intermediate layer 7. The composition of the coating layer 9 enables the print side 11 of the wallcover 1 to be printed by various printing technologies such as rotogravure, inkjet printing, flexography, screen printing, or laser jet.

[0040] When impregnated, the surface of the nonwoven substrate layer 3 is hydrophobic and has low porosity, which will prevent the overpenetration of the coating layer 9 in the nonwoven substrate layer 3.

[0041] The coating layer 9 may comprise pigments. Examples of suitable pigments include but are not limited to kaolin, calcium carbonate, and mixtures thereof, typically calcium carbonate.

[0042] The coating layer 9 is applied on the intermediate layer 7 of the nonwoven substrate layer 3 in an amount of 10 g / m2to 40 g / m2in dry weight.

[0043] In some embodiments, the coating layer 9 may be embossed.Wallcover properties

[0044] The wallcover 1, which comprises the nonwoven substrate layer 3 and the coating layer 9, may have a basis weight of 250-350 g / m2, preferably about 280-320 g / m2. In some embodiments, the basis weight can be lower, for example 230 g / m2.

[0045] The wallcover 1 will have a tearing strength. As used herein and in the claims, the tearing strength refers to the tearing strength measured according to ASTM D- 751 Pendulum Impulse Method standard. In preferred embodiments, the wallcover 1 has atearing strength in Machine Direction of at least 25%, when measured according to ASTM D-751 Pendulum Impulse Method standard. In preferred embodiments, the wallcover 1 will have a tearing strength in Cross Direction of at least 25%, when measured according to ASTM D-751- Pendulum Impulse Method standard.

[0046] The wallcover 1 will also have a shrinkage value, measured according to the W-102 Wallcovering Association quality standard. In some embodiments, the wallcover 1 has a shrinkage in Machine Direction of at most 2%, when measured according to the W- 102 Wallcovering Association quality standard, as disclosed in the experimental section. In some embodiments, it has a shrinkage in Cross Direction of at most 2%, when measured according to the W-102 Wallcovering Association quality standard, as disclosed in the experimental section.

[0047] In some embodiments, the wallcover 1 passes the stain resistance test for all 12 reagents when measured according to ASTM D-1308 standard. More particularly, these 12 reagents are: distilled cold water (1 mL, 23.9 + / - 2.8 °C), distilled hot water (1 mL, 48.9 + / - 2.8 °C), ethyl alcohol (1 mL, 50% by volume), vinegar (3% acetic acid), alkali solution (1 mL, 1% sodium hydroxide), acid solution (5% acetic or hydrochloric acid), soap solution (1 mL), detergent solution (1 mL), pure orange juice (1 mL), butter (1 mg), catsup (1 g), and tea (1 mL). In order to perform the stain resistance test, a predetermined quantity of the reagent is disposed on the wallcover and is allowed to stay on this wallcover for 24 hours. The spot is then wiped with a water or mild detergent and the examining for staining is performed visually to see if the wallcover holds stain and if the surface of the wallcover has been damaged by the presence of the reagent.

[0048] The wallcover 1 may have a scrubability value. The wallcover 1 typically has a scrubability of at least 300 cycles, when measured according to ASTM F793 standard.

[0049] The wallcover 1 will have a thickness of at least 400 pm, preferably in the range of 450 pm to 800 pm.

[0050] The wallcover 1 may have a lightness L* of at least 90; a color channel a* between -7 and +3; and a color channel b* between 2 and 12, when measured according to TAPPI 527 standard. The wallcover typically has an opacity of at least 90%, preferably of at least 95%, when measured according to ISO 2471 standard.

[0051] As stated above, the wallcover 1 meets Type II requirements in accordance with W-102 Wallcovering Association quality standard. Moreover, the present wallcovers 1show 25% of the CO emissions as compared to vinyl coated Type II wallcover according to toxicity test Boeing aircraft standard BSS 7239 (flaming). Further, the present wallcover 1 has 50% of the CO emissions as compared to TPO coated Type II wallcover according to toxicity test Boeing aircraft standard BSS 7239 (non-flaming). Accordingly, the wallcovers 1 according to the present invention are more environmentally friendly compared to the existing vinyl or TPO coated wallcovers.

[0052] The advantageous properties of the wallcover as described here-above enable its use on the surface of interior walls of a building, preferably in areas of medium wear according to W-102 Wallcovering Association quality standard. In a method of protecting a surface of an interior wall of a building in areas of medium wear according to W-102 Wallcovering Association quality standard, the interior wall is protected with a wallcover as described here-above.Methods of producing a wallcover

[0053] The nonwoven substrate layer 3 of the wallcover 1 described herein may be made by wet-laid paper-making technology. Thus both the backing layer 5 and the intermediate layer 7 of the nonwoven substrate layer 3 may be wet-laid nonwoven webs.

[0054] The method of producing a wallcover 1 comprises at least the following steps:- forming an intermediate layer 7 in a wet-laid process;- forming a backing layer 5 in a wet-laid process;- optionally pressing the layers together;- drying the layers to obtain a contiguous two-ply nonwoven sheet;- impregnating the dried two-ply nonwoven sheet by applying a binder composition that saturates into both sides of the two-ply nonwoven sheet;- drying the binder-treated two-ply nonwoven sheet to form a nonwoven substrate layer 3; and applying a coating layer 9 on top of the intermediate layer 7 of the obtained nonwoven substrate layer 3; wherein the backing layer 5 of the nonwoven substrate layer 3 comprises a mixture of cellulose fibers and coarse synthetic fibers and wherein the coarse synthetic fibers having alinear density of at least 5 dtex.

[0055] According to one embodiment, the intermediate layer 7 and the backing layer 5 may be formed on the same forming wire. The process may be a wet-laid dual headbox method comprising the steps of: forming a first fibrous slurry comprising the fibers of the intermediate layer 7 and a first solvent; forming a second fibrous slurry comprising the fibers of the backing layer 5 and a second solvent; transferring the first fibrous slurry to a first headbox zone while simultaneously transferring the second fibrous slurry to a second headbox zone; depositing the first fibrous slurry and the second fibrous slurry to a single continuous traveling forming wire wherein the first fibrous slurry is located on top of the second fibrous slurry; and applying a vacuum condition to the first fibrous slurry and the second fibrous slurry to remove at least a portion of the first solvent and / or the second solvent.

[0056] In preferred embodiments, the first solvent and the second solvent may comprise water.

[0057] In certain embodiments, the first headbox zone and the second headbox zone may comprise separate compartments of a single headbox. In other embodiments, the first headbox zone and the second headbox zone may comprise separate headboxes operating in tandem.

[0058] According to another embodiment, the intermediate layer 7 and the backing layer 5 may also be formed on separate forming wires. When formed on separate forming wires, the intermediate layer 7 and the backing layer 5 are combined when wet and optionally pressed together, typically with a wet press, before being dried as one two-ply nonwoven sheet. Drying may be carried out on a through air dryer. During drying, hydrogen bonds may be formed within the layers.

[0059] The method of producing the wallcover 1 may also comprise a step, wherein the wallcover 1 is calandered after the coating layer 9 is dried.

[0060] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0061] Reference throughout this specification to one embodiment or anembodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.

[0062] As used herein, a plurality of items, structural elements, compositional elements, and / or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

[0063] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.EXPERIMENTAL

[0064] The following test methods were employed to obtain the data reported in the tables below.Basis Weight: The basis weight is measured according to TAPPI Standard T410 and reported in grams per square meter (g / m2).Linear density: . Dtex (deci -tex) measures grams per 10,000 metres of fiber or yarn. Dtex is a direct measure of linear density.Tearing strength: Tearing strength in Machine Direction and in Cross Direction is measured according to ASTM D-751 Pendulum Impulse Method standard.Shrinkage: Shrinkage in Machine Direction and Cross Direction is measured according to W-102 Wallcovering Association quality standard, as specified in sections 7.1.2 and 7.1.3 of the standard. Briefly, three specimens (250 mm x 250 mm) are accurately measured in each direction to the nearest 0.5 mm. The specimens are soaked for 30 minutes in distilled water at room temperature, removed and dried at 87°C for 30 minutes. The specimens are then conditioned at the standard conditions as provided in ASTM Specification D-751 for a minimum of 8 hours prior to remeasuring. The percent shrinkage in each direction shall be calculated using the following formula:% Shrinkage = [(A - B) : A ] x 100, where A = length before test, B= length after test.Scrubability: Scrubability is measured according to ASTM F793 standard.Lightness and color channels: Lightness L, color channel a and color channel b were measured according to TAPPI 527 standard.Opacity: Opacity was measured according to ISO 2471 standard.Toxic gas generation on combustion: Toxic gas generation by materials on combustion was measured according to Boeing Aircraft Standard BSS 7239.

[0065] A wallcover 1 with the following nonwoven substrate layer 3 has been tested The table below illustrates the compositions of the different layers forming the nonwoven substrate layer 3. It has to be noted that the percentages reported in the table below are expressed by the percentage in the layer and not in the full nonwoven substrate layer 3.Table 1. Composition of nonwoven substrate layer 3

[0066] The here-above described backing layer 5 has a dry grammage of 144 g / m2and the intermediate layer 7 has a dry grammage of 22 g / m2. As described previously, the backing layer 5 and the intermediate layer 7 are intermingled, that is to say the fibers forming the backing layer 5 and the intermediate layer 7 are intermingled with each other which enables a good adhesion of the backing layer 5 with the intermediate layer 7 without the need of a lamination or adhesive as known in the prior art.

[0067] The nonwoven substrate layer 3 with the above presented composition once dried is impregnated by size press with the following binder composition. Table 2. Binder composition

[0068] The binder composition used for impregnating the nonwoven substrate layer 3 has a solid content of 33%. Moreover, the binder composition used for the impregnation of the nonwoven substrate layer 3 can further comprise some additives like pigments, antifoam agents, wetting agents, curing agents, or optical brightener alone or in combination. The nonwoven substrate layer 3 is impregnated with this binder composition in a dry amount of 102 g / m2.

[0069] Once the impregnated nonwoven substrate layer 3 has been dried, this nonwoven substrate layer 3 is coated with the coating layer 9 having the following composition.Table 3. Composition of the coating layer 9

[0070] The coating layer 9 is coated on the intermediate layer 7 of the nonwoven substrate layer 3 in a dry amount of 25 g / m2The produced wallcover 1 comprising the impregnated nonwoven substrate layer 3 and the coating layer 9 has a grammage of 296 g / m2.

[0071] The here-above presented wallcover 1 has been tested according to W-102 Wallcovering Association quality standard. Comparative wallcovers coated with TPO (Comparative wallcover 1) and with PVC (Comparative wallcover 2) and which both meet the Type II requirements as defined in W-102 Wallcovering Association quality standard have also been tested in order to evaluate the performances of the inventive wallcover 1. The comparative TPO coated wallcover has a grammage of 339.1 g / m2and the comparative PVC coated wallcover has a grammage of 440.8 g / m2. The obtained results are summarized in the table below.able 4. Test data according to W-102 Wallcovering Association quality standard

[0072] As shown in the above table, the wallcover 1 according to the invention shows improved grab tensile and tensile strength both in Machine Direction and in Cross Direction compared to the existing TPO or PVC coated wallcovers. Without willing to be bound by theory, the inventors believe that these improvements are due to the presence of the coarse synthetic fibers in the backing layer 5. The wallcover 1 of the present invention is stronger than the other existing wallcovers meeting Type II requirements.Results from burning tests

[0073] Furthermore, some burning tests according to Boeing aircraft standard BBS 7239 (flaming) of the several wallcovers presented here-above have been conducted and the results are summarized in the below table.Table 5. Burning tests according to Boeing aircraft standard BBS 7239 (flaming)Gaz emitted Test Mode

[0074] Typically the present wallcovers show 25% of the CO emissions as compared to vinyl coated Type II wallcover (Comparative wallcover 2) according to toxicity test Boeing aircraft standard BSS 7239 (flaming). The results show that the wallcover of the invention produces 25 ppm CO, whereas vinyl coated Type II wallcover shows 100 ppm CO in this test.

[0075] Moreover, the present wallcovers have 50% of the CO emissions as compared to TPO coated Type II wallcover (Comparative wallcover 1) according to toxicity test Boeing aircraft standard BSS 7239 (non-flaming). The results show that the wallcover of the invention produces 25 ppm CO, whereas TPO coated Type II wallcover shows 50 ppm CO in this test.

[0076] Embodiments of the invention include i.a. the following:1. A wallcover (1), comprising:- a nonwoven substrate layer (3) comprising: o a backing layer (5); and o an intermediate layer (7), disposed on one side of the backing layer (5); and- a coating layer (9) disposed on the intermediate layer (7); wherein the backing layer (5) comprises a mixture of cellulose fibers and of coarse synthetic fibers and wherein the coarse synthetic fibers having a linear density of at least 5 dtex.2. The wallcover (1) according to the preceding embodiment, wherein the backing layer (5) comprises a mixture of cellulose fibers, coarse synthetic fibers, and thin synthetic fibers.3. The wallcover (1) according to the preceding embodiment, wherein the thin synthetic fibers are present in the backing layer (5) at a level of 15 to 30 wt%, based on the total weight of the fibers in the backing layer (5).4. The wallcover (1) according to any one of embodiments 2 or 3, wherein the thin synthetic fibers have a linear density comprised between 1 dtex and 4 dtex, preferably between 1 and 3.5 dtex.5. The wallcover (1) according to any one of embodiments 2 to 4, wherein the thin synhetic fibers are selected from polyaramide fibers, polyamide fibers, polyester fibers, polyvinyl alcohol fibers, polypropylene fibers, glass fibers and combination thereof.6. The wallcover (1) according to any one of the preceding embodiments, wherein the coarse synthetic fibers are present in the backing layer (5) at a level of at least 5 wt%, preferably in a range of 5 to 30 wt%, more preferably in a range of 5 to 20 wt%, based on the total weight of the fibers in the backing layer (5).7. The nonwoven material according to any one of the preceding embodiments, wherein the coarse synthetic fibers have a length of at least 12 mm, preferably at least 18 mm.8. The wallcover (1) according to any one of the preceding embodiments, wherein the coarse synthetic fibers and the thin synthetic fibers are selected from polyaramide fibers, polyamide fibers, polyester fibers, polyvinyl alcohol fibers, polypropylene fibers, glass fibers, and combination thereof.9. The wallcover (1) according to any one of the preceding embodiments, wherein cellulose fibers are present in the backing layer (5) at a level of at least 50 wt%, preferably at least 60 wt%, based on the total weight of the fibers in the backing layer (5).10. The wallcover (1) according to any one of the preceding embodiments, wherein the backing layer (5) further comprises wet strength additives, dry strength additives or combinations thereof.11. The wallcover (1) according to any one of the preceding embodiments, wherein the backing layer (5) has a basis weight of 130 g / m2to 160 g / m212. The wallcover (1) according to any one of the preceding embodiments, wherein the intermediate layer (7) comprises or consists essentially of cellulose fibers.13. The wallcover (1) according to any one of the preceding embodiments, wherein the cellulose fibers are selected from bleached or unbleached hardwood pulp or softwood pulp, bleached or unbleached chemi-thermomechanical pulp from hardwood or softwood, bleached or unbleached chemical pulp from hardwood or softwood, and combinations thereof.14. The wallcover (1) according to any one of the preceding embodiments, wherein the intermediate layer (7) comprises 0-50 wt% of softwood fibers and 50-100 wt% of hardwood fibers, based on the total weight of the fibers of the intermediate layer (7).15. The wallcover (1) according to the preceding embodiments, wherein the hardwood fibers comprises a blend of eucalyptus fibers and birch fibers, preferably the eucalyptus fibers are present in an amount of at least 50 wt%, based on the total weight ofhardwood fibers, and the birch fibers are present in an amount of at most 50 wt%, based on the total weight of the hardwood fibers16. The wallcover (1) according to any one of the preceding embodiments, wherein the intermediate layer (7) has a basis weight of 10 g / m2to 30 g / m217. The wallcover (1) according to any one of the preceding embodiments, wherein the fibers from the backing layer (5) and the intermediate layer (7) are intermingled at the interface of the layers.18. The wallcover (1) according to any one of the preceding embodiments, wherein the nonwoven substrate layer (3) is impregnated with an impregnation composition.19. The wallcover (1) according to embodiment 18, wherein the impregnation composition comprises a binder, fillers, and optionally additives.20. The wallcover (1) according to embodiment 19, wherein the binder is chosen among styrene acrylate, acrylic, latex, ultra-low formaldehyde acrylic, and combination thereof.21. The wallcover (1) according to any of embodiments 19 or 20, wherein the binder has a glass transition temperature of between -25°C and +10°C.22. The wallcover (1) according to any one of embodiments 19 to 21, wherein the fillers are chosen among kaolin, calcium carbonate, titanium dioxide, or combination thereof.23. The wallcover (1) according to any one of embodiments 18 to 22, wherein the nonwoven substrate layer (3) is impregnated with the impregnation composition in an amount of 80 g / m2to 120 g / m2.24. The wallcover (1) according to any one of the preceding embodiments, wherein the coating layer (9) comprises acrylic resins and pigments.25. The wallcover (1) according to the preceding embodiment, wherein the acrylic resin is a hydrophobic styrene acrylic resin.26. The wallcover (1) according to any one of embodiments 24 or 25, wherein the pigments are chosen among kaolin, calcium carbonate, and mixtures thereof.27. The wallcover (1) according to any one of the preceding embodiments, wherein the coating layer (9) is coated on the intermediate layer (7) of the nonwoven substrate layer (3) in an amount of 10 g / m2to 40 g / m2in dry weight.28. The wallcover (1) according to any one of the preceding embodiments, wherein it has a basis weight of 250-350 g / m2, preferably about 280-320 g / m2.29. The wallcover (1) according to any one of the preceding embodiments, wherein it has a tearing strength in Machine Direction of at least 25%, when measured according to ASTM D-751 Pendulum Impulse Method standard.30. The wallcover (1) according to any one of the preceding embodiments, wherein it has a tearing strength in Cross Direction of at least 25%, when measured according to ASTM D-751- Pendulum Impulse Method standard.31. The wallcover (1) according to any one of the preceding embodiments, wherein it has a shrinkage in Machine Direction of at most 2%, when measured according to the W-102 Wallcovering Association quality standard.32. The wallcover (1) according to any one of the preceding embodiments, wherein it has a shrinkage in Cross Direction of at most 2%, when measured according to the W-102 Wallcovering Association quality standard.33. The wallcover (1) according to any one of the preceding embodiments, wherein it has a scrubability of at least 300 cycles, when measured according to ASTM F793 standard.34. The wallcover (1) according to any one of the preceding embodiments, wherein it meets Type II requirements in accordance with W-102 Wallcovering Association quality standard.35. The wallcover (1) according to any one of the preceding embodiments, wherein it has a lightness L* of at least 90, a color channel a* between -7 and +3, and a color channel b* between 2 and 12, when measured according to TAPPI 527 standard.36. The wallcover (1) according to any one of the preceding embodiments, wherein it has a thickness of at least 400pm.37. The wallcover (1) according to any one of the preceding embodiments, wherein it has an opacity of at least 90%, preferably of at least 95%, when measured according to ISO 2471 standard.38. The wallcover (1) according to any one of the preceding embodiments, wherein the coating layer (9) is embossed.39. The wallcover according to any one of the preceding embodiments, wherein a print side (11) of the coating layer (9) is printed, said print side (11) being disposed on the side of the coating layer (9) opposite to the side in contact with the intermediate layer (7).40. A method of producing a wallcover (1), comprising the steps of:- forming an intermediate layer (7) in a wet-laid process;- forming a backing layer (5) in a wet-laid process;- drying the layers to obtain a contiguous two-ply nonwoven sheet;- impregnating the dried two-ply nonwoven sheet by applying a binder composition that saturates into both sides of the two-ply nonwoven sheet;- drying the binder-treated two-ply nonwoven sheet to form a nonwoven substrate layer (3); and- applying a coating layer (9) on top of the intermediate layer (7) of the obtained nonwoven substrate layer (3); wherein the backing layer (5) of the nonwoven substrate layer (3) comprises a mixture of cellulose fibers and coarse synthetic fibers and wherein the coarse synthetic fibers having a linear density of at least 5 dtex.41. The method according to embodiment 40, wherein the backing layer (5) and the intermediate layer (7) are formed on the same forming wire.42. The method according to embodiment 40, wherein the backing layer (5) and the intermediate layer (7) are formed on separate forming wires, combined when wet and optionally pressed together before being dried as one nonwoven sheet on the through air dryer.43. The method according to any one of embodiments 40 to 42, comprising a step of pressing the layers together, preferably using a wet press, before the step of drying the layers to obtain a contiguous two-ply nonwoven sheet.44. The method according to any one of embodiments 40 to 43, wherein the nonwoven web is calandered after the step of applying the coating layer (9).45. Use of a wallcover according to any one of embodiments 1 to 39 on the surface of interior walls of a building, preferably in areas of medium wear according to W- 102 Wallcovering Association quality standard.46. A method of protecting a surface of an interior wall of a building in areas of medium wear according to W-102 Wallcovering Association quality standard with a wallcover according to any one of embodimnets 1 to 39.

[0077] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementationcan be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[0078] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", that is, a singular form, throughout this document does not exclude a plurality.INDUSTRIAL APPLICABILITY

[0079] The present technology can be employed for the manufacture of wallcoverings, which meet the Type II requirements set for wall covers intended for use in areas of medium wear. The wallcovers can be utilized as traditional wall papers for decorative purposes, domestically and in public spaces. CITATION LISTPatent LiteratureUS 2005 / 0014431CN112318955A

Claims

CLAIMS:

1. A wallcover (1), comprising:- a nonwoven substrate layer (3) comprising: o a backing layer (5); and o an intermediate layer (7), disposed on one side of the backing layer (5); and- a coating layer (9) disposed on the intermediate layer (7); wherein the backing layer (5) comprises a mixture of cellulose fibers and of coarse synthetic fibers and wherein the coarse synthetic fibers having a linear density of at least 5 dtex.

2. The wallcover (1) according to the preceding claim, wherein the backing layer (5) comprises a mixture of cellulose fibers, coarse synthetic fibers, and thin synthetic fibers.

3. The wallcover (1) according to the preceding claim, wherein the thin synthetic fibers are present in the backing layer (5) at a level of 15 to 30 wt%, based on the total weight of the fibers in the backing layer (5).

4. The wallcover (1) according to any one of claims 2 or 3, wherein the thin synthetic fibers have a linear density comprised between 1 dtex and 4 dtex, preferably between 1 and 3.5 dtex.

5. The wallcover (1) according to any one of claims 2 to 4, wherein the thin synhetic fibers are selected from polyaramide fibers, polyamide fibers, polyester fibers, polyvinyl alcohol fibers, polypropylene fibers, glass fibers and combination thereof.

6. The wallcover (1) according to any one of the preceding claims, wherein the coarse synthetic fibers are present in the backing layer (5) at a level of at least 5 wt%, preferably in a range of 5 to 30 wt%, more preferably in a range of 5 to 20 wt%, based on the total weight of the fibers in the backing layer (5).

7. The nonwoven material according to any one of the preceding claims, wherein the coarse synthetic fibers have a length of at least 12 mm, preferably at least 18 mm.

8. The wallcover (1) according to any one of the preceding claims, wherein the coarse synthetic fibers and the thin synthetic fibers are selected from polyaramide fibers, polyamide fibers, polyester fibers, polyvinyl alcohol fibers, polypropylene fibers, glass fibers, and combination thereof.

9. The wallcover (1) according to any one of the preceding claims, wherein cellulose fibers are present in the backing layer (5) at a level of at least 50 wt%, preferably at least 60 wt%, based on the total weight of the fibers in the backing layer (5).

10. The wallcover (1) according to any one of the preceding claims, wherein the backing layer (5) further comprises wet strength additives, dry strength additives or combinations thereof.

11. The wallcover (1) according to any one of the preceding claims, wherein the backing layer (5) has a basis weight of 130 g / m2to 160 g / m212. The wallcover (1) according to any one of the preceding claims, wherein the intermediate layer (7) comprises or consists essentially of cellulose fibers.

13. The wallcover (1) according to any one of the preceding claims, wherein the cellulose fibers are selected from bleached or unbleached hardwood pulp or softwood pulp, bleached or unbleached chemi-thermomechanical pulp from hardwood or softwood, bleached or unbleached chemical pulp from hardwood or softwood, and combinations thereof.

14. The wallcover (1) according to any one of the preceding claims, wherein the intermediate layer (7) comprises 0-50 wt% of softwood fibers and 50-100 wt% of hardwood fibers, based on the total weight of the fibers of the intermediate layer (7).

15. The wallcover (1) according to the preceding claim, wherein the hardwood fibers comprises a blend of eucalyptus fibers and birch fibers, preferably the eucalyptus fibers are present in an amount of at least 50 wt%, based on the total weight of hardwoodfibers, and the birch fibers are present in an amount of at most 50 wt%, based on the total weight of the hardwood fibers16. The wallcover (1) according to any one of the preceding claims, wherein the intermediate layer (7) has a basis weight of 10 g / m2to 30 g / m217. The wallcover (1) according to any one of the preceding claims, wherein the fibers from the backing layer (5) and the intermediate layer (7) are intermingled at the interface of the layers.

18. The wallcover (1) according to any one of the preceding claims, wherein the nonwoven substrate layer (3) is impregnated with an impregnation composition.

19. The wallcover (1) according to claim 18, wherein the impregnation composition comprises a binder, fillers, and optionally additives.

20. The wallcover (1) according to claim 19, wherein the binder is chosen among styrene acrylate, acrylic, latex, ultra-low formaldehyde acrylic, and combination thereof.

21. The wallcover (1) according to any of claims 19 or 20, wherein the binder has a glass transition temperature of between -25°C and +10°C.

22. The wallcover (1) according to any one of claims 19 to 21, wherein the fillers are chosen among kaolin, calcium carbonate, titanium dioxide, or combination thereof.

23. The wallcover (1) according to any one of claims 18 to 22, wherein the nonwoven substrate layer (3) is impregnated with the impregnation composition in an amount of 80 g / m2to 120 g / m2.

24. The wallcover (1) according to any one of the preceding claims, wherein the coating layer (9) comprises acrylic resins and pigments.

25. The wallcover (1) according to the preceding claim, wherein the acrylic resin is a hydrophobic styrene acrylic resin.

26. The wallcover (1) according to any one of claims 24 or 25, wherein the pigments are chosen among kaolin, calcium carbonate, and mixtures thereof.

27. The wallcover (1) according to any one of the preceding claims, wherein the coating layer (9) is coated on the intermediate layer (7) of the nonwoven substrate layer (3) in an amount of 10 g / m2to 40 g / m2in dry weight.

28. The wallcover (1) according to any one of the preceding claims, wherein it has a basis weight of 250-350 g / m2, preferably about 280-320 g / m2.

29. The wallcover (1) according to any one of the preceding claims, wherein it has a tearing strength in Machine Direction of at least 25%, when measured according to ASTM D-751 Pendulum Impulse Method standard.

30. The wallcover (1) according to any one of the preceding claims, wherein it has a tearing strength in Cross Direction of at least 25%, when measured according to ASTM D-751- Pendulum Impulse Method standard.

31. The wallcover (1) according to any one of the preceding claims, wherein it has a shrinkage in Machine Direction of at most 2%, when measured according to the W- 102 Wallcovering Association quality standard.

32. The wallcover (1) according to any one of the preceding claims, wherein it has a shrinkage in Cross Direction of at most 2%, when measured according to the W-102 Wallcovering Association quality standard.

33. The wallcover (1) according to any one of the preceding claims, wherein it has a scrubability of at least 300 cycles, when measured according to ASTM F793 standard.

34. The wallcover (1) according to any one of the preceding claims, wherein it meets Type II requirements in accordance with W-102 Wallcovering Association quality standard.

35. The wallcover (1) according to any one of the preceding claims, wherein it has a lightness L* of at least 90, a color channel a* between -7 and +3, and a color channel b* between 2 and 12, when measured according to TAPPI 527 standard.

36. The wallcover (1) according to any one of the preceding claims, wherein it has a thickness of at least 400pm.

37. The wallcover (1) according to any one of the preceding claims, wherein it has an opacity of at least 90%, preferably of at least 95%, when measured according to ISO 2471 standard.

38. The wallcover (1) according to any one of the preceding claims, wherein the coating layer (9) is embossed.

39. The wallcover according to any one of the preceding claims, wherein a print side (11) of the coating layer (9) is printed, said print side (11) being disposed on the side of the coating layer (9) opposite to the side in contact with the intermediate layer (7).

40. A method of producing a wallcover (1), comprising the steps of:- forming an intermediate layer (7) in a wet-laid process;- forming a backing layer (5) in a wet-laid process;- drying the layers to obtain a contiguous two-ply nonwoven sheet;- impregnating the dried two-ply nonwoven sheet by applying a binder composition that saturates into both sides of the two-ply nonwoven sheet;- drying the binder-treated two-ply nonwoven sheet to form a nonwoven substrate layer (3); and- applying a coating layer (9) on top of the intermediate layer (7) of the obtained nonwoven substrate layer (3); wherein the backing layer (5) of the nonwoven substrate layer (3) comprises a mixture of cellulose fibers and coarse synthetic fibers and wherein the coarse synthetic fibers having a linear density of at least 5 dtex.

41. The method according to claim 40, wherein the backing layer (5) and the intermediate layer (7) are formed on the same forming wire.

42. The method according to claim 40, wherein the backing layer (5) and the intermediate layer (7) are formed on separate forming wires, combined when wet and optionally pressed together before being dried as one nonwoven sheet on the through air dryer.

43. The method according to any one of claims 40 to 42, comprising a step of pressing the layers together, preferably using a wet press, before the step of drying the layers to obtain a contiguous two-ply nonwoven sheet.

44. The method according to any one of claims 40 to 43, wherein the nonwoven web is calandered after the step of applying the coating layer (9).

45. Use of a wallcover according to any one of claims 1 to 39 on the surface of interior walls of a building, preferably in areas of medium wear according to W-102 Wallcovering Association quality standard.

46. A method of protecting a surface of an interior wall of a building in areas of medium wear according to W-102 Wallcovering Association quality standard with a wallcover according to any one of claims 1 to 39.

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