Wall coating and production method thereof

Abstract

In accordance with an exemplary aspect of the present invention, a wall coating is provided that includes a nonwoven substrate layer having a backing layer and an intermediate layer, the intermediate layer disposed on one side of the backing layer, and a coating layer disposed on the intermediate layer. The backing layer includes a mixture of cellulosic fibers and crude synthetic fibers. The invention also relates to a method for producing a wall coating. The invention provides an environmentally friendly wall coating that can be produced in a single process stage without the need for multiple manufacturing steps.

Description

Technical Field

[0001] The present invention relates to a wall coating, and more particularly to a wall coating for high traffic areas. Specifically, the present invention relates to a wall coating comprising a nonwoven substrate layer having 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 present invention also relates to a method for producing the wall coating. The present invention provides an environmentally friendly wall coating that can be produced in a single process stage without multiple manufacturing steps. Background Art

[0002] Traditionally, the construction of wall coatings includes a two-step process to produce a three-layer construction. The three-layer structure includes a substrate or backing layer, an intermediate layer, and a decorative layer. The substrate or backing layer is usually composed of a tissue material, a woven fabric, or some other type of nonwoven material. The substrate layer is laminated to the intermediate layer, which usually includes vinyl or a vinyl substitute. The intermediate layer containing vinyl or a vinyl substitute provides strength and structure to the final product. It also provides a background color and provides additional flexibility for printing. The decorative layer is applied on top of the intermediate layer and can be produced using various types of methods, such as rotogravure printing, flexographic printing, digital printing, and screen printing. The decorative layer usually includes ink and an optional protective coating.

[0003] The conventional production process involves applying a decorative layer on an intermediate vinyl / vinyl replacement layer, followed by laminating the intermediate layer on a backing layer. The conventional process and the wall coating produced thereby have various disadvantages, including the need for an additional lamination step which increases operating and material costs, and the inclusion of a less environmentally friendly vinyl / vinyl replacement layer in the wall coating.

[0004] In several countries, there are nationally recognized quality standards for wall coatings for institutional and commercial use. In the United States, different physical requirements and test methods are set for wall coatings classified as Class I (light duty, for low wear areas, such as residential use), Class II (medium duty, hotels, etc.), and Class III (heavy duty, such as hospitals). The requirements and test methods are disclosed in the Wall Coatings Association Quality Standards W-101 (2017, for polymer-coated fabric wall coatings) and W-102 (2019, for alternative constructions other than vinyl wall coatings).

[0005] Prior art wall coating materials that meet Class II requirements are typically PVC (polyvinyl chloride) coatings or TPO (thermoplastic olefin) coatings. Such PVC or TPO coated papers are applied off-line, which is time-consuming and labor-intensive. In addition, the use of PVC creates problems: the raw materials containing PVC may release undesirable volatile organic compounds during the production process and during use. It is well known that PVC coated papers are particularly harmful during combustion, which poses additional health risks to occupants and firefighters. When burned, PVC coated wall coating papers release harmful and toxic fumes, such as hydrochloric acid.

[0006] US2005 / 0014431 discloses a wall coating paper coated with a plastic layer of a thermoplastic olefin-containing material. The plastic layer comprises a TPO polymer and an optional filler such as CaCO3 or TiO2. The plastic layer is intended to be printed / printed. The base substrate disclosed in the document is a non-woven web comprising natural and / or synthetic fibers, a binder (more particularly an acrylic binder) and a filler (particularly clay). In one embodiment, the base substrate can be a double-layer non-woven web. It should also be noted that TPO-coated wall coatings tend to burn quickly or spread fire more when exposed to fire, and are plastic-based materials that are not environmentally friendly. CN112318955A relates to a wall coating comprising a bottom layer of polyester staple fibers and a surface layer comprising wood pulp fibers, which are manufactured in separate process steps.

[0007] In order to solve the problems associated with the conventional process, it has now been found that the wall coating can be constructed with more environmentally friendly materials through a single-step process and by eliminating the lamination step. Therefore, the present invention discloses a wall coating that is composed of environmentally friendly materials and can be constructed in a single-step process and meets the quality standards set for wall coatings, in particular the Class II requirements defined in the W-102 Wall Coating Association Quality Standard. Summary of the invention

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

[0009] As stated above, one of the objects of the present invention is to eliminate at least some of the problems associated with the prior art and to provide a wall coating and a method for producing a wall coating having the above-mentioned advantageous properties.

[0010] The present invention is based on the concept of using a more environmentally friendly wet-laid nonwoven material as a wall coating construction material and eliminating the vinyl / vinyl substitute intermediate layer, but the wall coating has the required properties, such as tear strength and scrubbability, to meet Class II requirements. The method of the present invention includes a single-step process in which the intermediate layer and the backing layer of the wall coating are formed together by hydrogen bonding and fiber interlocking, thereby eliminating the need for an additional lamination step.

[0011] According to a first aspect of the present invention, there is provided a wall coating comprising:

[0012] - a nonwoven substrate layer comprising:

[0013] a backing layer; and

[0014] an intermediate layer disposed on one side of the backing layer; and

[0015] - a coating layer disposed on the intermediate layer;

[0016] Wherein the backing layer comprises a mixture of cellulosic fibers and 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.

[0017] According to a second aspect of the present invention, there is provided a method for producing a wall coating, wherein the method comprises the following steps:

[0018] - Formation of an intermediate layer during wet-laying;

[0019] - forming a backing layer during wet-laying;

[0020] - optionally pressing the layers together;

[0021] - drying the layers to obtain a continuous two-layer nonwoven sheet;

[0022] - impregnating the dried double-layer nonwoven sheet by applying a binder composition that penetrates into both sides of the double-layer nonwoven sheet;

[0023] - drying the double-layer nonwoven sheet treated with the binder to form a nonwoven substrate layer; and

[0024] - applying a coating layer on top of the intermediate layer of the obtained nonwoven substrate layer;

[0025] Wherein the backing layer of the double-layer nonwoven sheet comprises a mixture of cellulosic fibers and coarse synthetic fibers, and wherein the coarse synthetic fibers have a linear density of at least 5 dtex.

[0026] According to a third aspect of the invention there is provided the use of a wall coating as described above on the surface of an interior wall of a building, preferably in the medium wear area according to the W-102 Wall Coatings Association quality standard.

[0027] According to a fourth aspect of the present invention there is provided a method of protecting the surface of an interior wall of a building in the medium wear area according to the W-102 Wall Coating Association quality standard using a wall coating as described above.

[0028] Considerable advantages are achieved with the present invention. First, the wall coatings of the present invention are more environmentally friendly because the use of vinyl, vinyl substitutes, olefins, and adhesives are avoided. However, the wall coatings of the present invention meet the Class II requirements set for wall coatings used in moderate wear areas. Thus, the present invention provides a Class II wall coating material that is more environmentally friendly while meeting or exceeding the W-102 Wall Coating Association quality standard performance for Class II wall coatings.

[0029] Second, the wall coatings of the present invention can be produced in a single processing stage, thus making them cheaper and faster to manufacture than existing Class II wall coating materials that require multiple steps to manufacture. The substrate layer of the wall coating of the present invention is produced without adhesives and lamination steps.

[0030] Furthermore, the wall coating of the present invention shows superior results in a combustion test compared to existing PVC-containing Class II wall coating materials, which release harmful and toxic fumes during combustion. In addition, the wall coating of the present invention is easy to print, stain-resistant and scrub-resistant, and shows good dimensional stability and minimal shrinkage.

[0031] Further features and advantages of the present technology will emerge from the following description of some embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A side view of a wall coating according to at least some embodiments of the present invention is shown, with the following reference numerals: (1) wall coating; (3) nonwoven substrate layer; (5) backing layer; (7) intermediate layer; (9) coating layer; (11) printed side of wall coating 1. DETAILED DESCRIPTION

[0033] Figure 1 The wall coating 1 according to the present invention is shown, and the wall coating 1 comprises:

[0034] - Nonwoven substrate layer 3, comprising:

[0035] a backing layer 5; and

[0036] an intermediate layer 7 disposed on one side of the backing layer 5; and

[0037] - a coating layer 9, which is arranged on the intermediate layer 7;

[0038] Therein, the backing layer 5 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.

[0039] As used herein and in the claims, the term "nonwoven" or "web" refers to a collection of fibers in a plurality of such fibers that are randomly interlocked, entangled, and / or bonded to one another to form a structural element.

[0040] As used herein, "synthetic fibers" refer to fibers made from fiber-forming substances, including polymers synthesized from chemical compounds and modified or converted natural polymers. Preferred non-limiting examples of synthetic fibers include polyaramid fibers, polyamide fibers, polyester fibers, polyvinyl alcohol fibers, polypropylene fibers, glass fibers, and combinations thereof.

[0041] Synthetic fibers will have a synthetic fiber length. As used herein, a "thick synthetic fiber" has a length of at least 12 mm, preferably at least 18 mm. In some embodiments, the length of the thick synthetic fiber may be no greater than 45 mm, or no greater than 35 mm. For example, the length of the thick synthetic fiber may be in the range of 12 mm to 45 mm, or 18 mm to 35 mm.

[0042] As used herein and in the claims, "fine synthetic fibers" shall have a synthetic fiber length. The preferred synthetic fiber length of the fine synthetic fibers may be no greater than 15 mm, preferably the length of the fine synthetic fibers is comprised between 5 mm and 12 mm.

[0043] The synthetic fibers may have a linear density or linear mass. Coarse synthetic fibers may have a linear density of at least 5 dtex, for example, the linear density of coarse synthetic fibers may be between 5 dtex and 10 dtex. The linear density of fine synthetic fibers may be between 1 dtex and 4 dtex, preferably between 1 dtex and 3.5 dtex.

[0044] The backing layer 5 of the nonwoven substrate layer 3 includes a mixture of cellulosic fibers and coarse synthetic fibers. In some embodiments, the fibers in the backing layer 5 consist of cellulosic fibers and coarse synthetic fibers.

[0045] In some embodiments, the backing layer 5 comprises a mixture of cellulose fibers, coarse synthetic fibers and fine synthetic fibers. In some embodiments, the fibers in the backing layer 5 consist of cellulose fibers, coarse synthetic fibers and fine synthetic fibers.

[0046] The amount of cellulose fibers, coarse synthetic fibers, and optional fine synthetic fibers can be expressed as weight percentages based on the total weight of fibers in the backing layer 5. In some embodiments, cellulose fibers can 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 fibers in the backing layer 5. In some embodiments, coarse synthetic fibers can be present in the backing layer 5 at a level of at least 5 wt%, preferably in the range of 5 to 30 wt%, more preferably in the range of 5 to 20 wt%, based on the total weight of fibers in the backing layer 5. In some embodiments, fine synthetic fibers can be present in the backing layer 5 at a level of 15 to 30 wt%, based on the total weight of fibers in the backing layer 5. The strength properties of the wall coating 1, such as tensile strength, tear strength, and puncture resistance, can be adjusted by changing the percentage of coarse synthetic fibers in the backing layer 5.

[0047] In some embodiments, the fibers in the backing layer 5 may comprise 5 to 20 wt% coarse synthetic fibers and 20 to 25 wt% fine synthetic fibers, based on the total weight of the fibers in the backing layer 5, with the remainder of the fibers comprising cellulose fibers.

[0048] Preferably, the coarse synthetic fibers are selected from the group consisting of aramid fibers, polyamide fibers, polyester fibers, polyvinyl alcohol fibers, polypropylene fibers, glass fibers, and combinations thereof. When used, the fine synthetic fibers may be selected from the group consisting of aramid 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 nylons, such as nylon-t; nylon 6,6; nylon-6,12, and the like.

[0049] In some embodiments, the backing layer 5 may further comprise additives, typically wet strength additives, dry strength additives, or combinations thereof.

[0050] The basis weight of the backing layer 5 is usually 130 g / m 2 Up to 160g / m 2 .

[0051] In addition to the backing layer 5, the nonwoven substrate layer 3 of the wall coating comprises an intermediate layer 7, which is disposed on one side of the backing layer 5. The intermediate layer 7 generally comprises or consists essentially of cellulose fibers. The cellulose fibers may comprise bleached or unbleached hardwood pulp or softwood pulp, bleached or unbleached chemical thermomechanical pulp from hardwood or softwood, bleached or unbleached chemical pulp from hardwood or softwood, and combinations thereof.

[0052] In some embodiments, the middle layer 7 comprises 0-50 wt% softwood fibers and 50-100 wt% hardwood fibers, based on the total weight of the fibers of the middle layer 7. In some embodiments, the middle layer 7 may comprise up to 5 wt% softwood fibers and at least 95 wt% hardwood fibers. In some embodiments, the fibers of the middle layer 7 consist of or consist essentially of hardwood fibers. The middle layer 7 comprising a high proportion of hardwood fibers has a very low porosity and therefore has a high smoothness.

[0053] In some embodiments, the hardwood fibers in the middle layer 7 include a mixture 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 the hardwood fibers, and the birch fibers are present in an amount of up to 50 wt% based on the total weight of the hardwood fibers. In some embodiments, the hardwood fibers may include a mixture 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 of about 25 wt% based on the total weight of the hardwood fibers. This mixture of hardwood fibers can have a smooth surface middle layer 7, thereby improving the deposition quality of the coating layer 9, which will also improve the printability of the wall coating 1. In particular, the eucalyptus fibers are small and help to improve the smoothness of the middle layer 7 and the forming of the sheet forming the middle layer 7.

[0054] The middle layer 7 usually has a thickness of 10 g / m 2 Up to 30g / m 2 The basis weight.

[0055] The backing layer 5 and the intermediate layer 7 disposed on one side of the backing layer 5 are mixed at the interface of the layers, and hydrogen bonding occurs between the layers during dehydration and drying, thereby forming the nonwoven substrate layer 3. No adhesive layer or lamination step is required to achieve adhesion between the backing layer 5 and the intermediate layer 7 in the nonwoven substrate layer 3.

[0056] In certain embodiments, the nonwoven substrate layer 3 can be impregnated with an impregnation composition. The impregnation composition can include a binder, a filler and an optional additive. Typically, a suitable binder is selected from styrene acrylate, acrylic resin, latex, ultra-low (<20ppm) formaldehyde acrylic resin and a combination thereof. In some preferred embodiments, a binder with a glass transition temperature between -25°C and +10°C can be selected. The impregnation composition comprising a binder with a glass transition temperature between -25°C and +10°C can make the impregnated nonwoven substrate layer 3 have flexibility.

[0057] The filler of the impregnation composition may be selected from kaolin, calcium carbonate, titanium dioxide or a combination thereof. The impregnation composition may contain additives, typically selected from pigments, defoamers, wetting agents, curing agents, fluorescent brighteners and any combination thereof.

[0058] When impregnated, the nonwoven substrate layer 3 may be made of 80 g / m 2 Up to 120g / m 2 The impregnation is carried out in an amount of the impregnation composition.

[0059] The wall coating 1 also includes a coating layer 9 arranged on the middle layer 7 of the nonwoven substrate layer 3. The coating layer 9 brings additional resistance, smoothness and scrubability to the wall coating 1. The coating layer 9 may include, for example, acrylic resin and pigment. 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 the printing side 11 of the wall coating 1, which is intended to receive printing thereon. Therefore, in some embodiments, the printing side 11 of the coating layer 9 is printed, and the printing side 11 is arranged on the side opposite to the side of the contacting middle layer 7 of the coating layer. The composition of the coating layer 9 enables the printing side 11 of the wall coating 1 to be printed by various printing techniques, such as rotary gravure printing, inkjet printing, flexographic printing, screen printing or laser jetting.

[0060] When impregnated, the surface of the nonwoven substrate layer 3 is hydrophobic and has a low porosity, which will prevent the coating layer 9 from excessively penetrating into the nonwoven substrate layer 3 .

[0061] The coating layer 9 may include a pigment. Examples of suitable pigments include, but are not limited to, kaolin, calcium carbonate, and mixtures thereof, with calcium carbonate being typical.

[0062] Coating layer 9 with 10g / m 2 Up to 40g / m 2 The amount of dry weight is applied to the middle layer 7 of the nonwoven substrate layer 3.

[0063] In some embodiments, coating layer 9 may be printed.

[0064] Wall coating properties

[0065] The wall coating 1 including the nonwoven substrate layer 3 and the coating layer 9 may have a weight of 250-350 g / m 2 , preferably about 280-320g / m 2 In some embodiments, the basis weight can be lower, such as 230 g / m 2 .

[0066] The wall coating 1 will have a tear strength. As used herein and in the claims, tear strength refers to the tear strength measured according to the ASTM D-751 pendulum pulse method standard. In a preferred embodiment, the wall coating 1 has a tear strength of at least 25% in the machine direction when measured according to the ASTM D-751 pendulum pulse method standard. In a preferred embodiment, the wall coating 1 has a tear strength of at least 25% in the cross direction when measured according to the ASTM D-751-Pendulum Pulse Method Standard.

[0067] Wall Coating 1 will also have a shrinkage value measured according to the W-102 Wall Coating Association quality standard. In some embodiments, Wall Coating 1 has a shrinkage of at most 2% in the machine direction when measured according to the W-102 Wall Coating Association quality standard, as disclosed in the experimental section. In some embodiments, its shrinkage in the cross direction is at most 2% when measured according to the W-102 Wall Coating Association quality standard, as disclosed in the experimental section.

[0068] In some embodiments, when measured according to the ASTM D-1308 standard, the wall coating 1 passes the stain resistance test of all 12 reagents. More specifically, the 12 reagents are: distilled cold water (1 mL, 23.9 + / - 2.8 ° C), distilled hot water (1 mL, 48.9 + / - 2.8 ° C), ethanol (1 mL, 50% volume), vinegar (3% acetic acid), alkaline solution (1 mL, 1% sodium hydroxide), acid solution (5% acetic acid or hydrochloric acid), soap solution (1 mL), detergent solution (1 mL), pure orange juice (1 mL), butter (1 mg), ketchup (1 g) and tea (1 mL). For stain resistance testing, a predetermined amount of reagent is placed on the wall coating and allowed to stay on the wall coating for 24 hours. The stain is then wiped with water or a mild detergent and the stain is visually inspected to see if the wall coating is left with stains and whether the surface of the wall coating is damaged by the presence of the reagents.

[0069] The wall coating 1 may have a scrubability value. When measured according to the ASTM F793 standard, the wall coating 1 typically has a scrubability of at least 300 cycles.

[0070] The wall coating 1 will have a thickness of at least 400 μm, preferably in the range of 450 μm to 800 μm.

[0071] When measured according to the TAPPI 527 standard, the wall coating 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 the ISO 2471 standard, the wall coating generally has an opacity of at least 90%, preferably at least 95%.

[0072] As described above, according to the W-102 Wall Coating Association quality standard, the wall coating 1 meets the Class II requirements. In addition, according to the toxicity test Boeing aircraft standard BSS 7239 (burning), compared with the vinyl coated Class II wall coating, the wall coating 1 shows 25% CO emissions. In addition, according to the toxicity test Boeing aircraft standard BSS 7239 (non-burning), compared with the TPO coated Class II wall coating, the wall coating 1 of the present invention has 50% CO emissions. Therefore, compared with the existing wall coatings coated with vinyl or TPO, the wall coating 1 according to the present invention is more environmentally friendly.

[0073] The advantageous properties of the wall coating as described above enable it to be used on the surfaces of the interior walls of buildings, preferably in areas of moderate wear, according to the W-102 Wall Coating Association quality standard. In a method for protecting the surfaces of the interior walls of buildings in areas of moderate wear according to the W-102 Wall Coating Association quality standard, the interior walls are protected with a wall coating as described above.

[0074] Method for producing wall coating

[0075] The nonwoven substrate layer 3 of the wall coating 1 described here can be made by wet-laid papermaking technology. Therefore, the backing layer 5 and the middle layer 7 of the nonwoven substrate layer 3 can both be wet-laid nonwoven webs.

[0076] The method for producing the wall coating 1 comprises at least the following steps:

[0077] - forming the intermediate layer 7 during the wet-laid process;

[0078] - forming the backing layer 5 during the wet-laid process;

[0079] - optionally pressing the layers together;

[0080] - drying the layers to obtain a continuous two-layer nonwoven sheet;

[0081] - impregnating the dried double-layer nonwoven sheet by applying a binder composition that penetrates into both sides of the double-layer nonwoven sheet;

[0082] - drying the double-layer nonwoven sheet treated with the binder to form a nonwoven substrate layer 3; and

[0083] - applying a coating layer 9 on top of the intermediate layer 7 of the obtained nonwoven substrate layer 3;

[0084] Therein, 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 have a linear density of at least 5 dtex.

[0085] According to one embodiment, the middle layer 7 and the backing layer 5 can be formed on the same forming wire. The process can be a wet-laid twin headbox method, which includes the following steps: forming a first fiber slurry containing fibers of the middle layer 7 and a first solvent; forming a second fiber slurry containing fibers of the backing layer 5 and a second solvent; transferring the first fiber slurry to the first headbox area while transferring the second fiber slurry to the second headbox area; depositing the first fiber slurry and the second fiber slurry onto a single continuously traveling forming wire, wherein the first fiber slurry is located on top of the second fiber slurry; and applying vacuum conditions to the first fiber slurry and the second fiber slurry to remove at least a portion of the first solvent and / or the second solvent.

[0086] In a preferred embodiment, the first solvent and the second solvent may contain water.

[0087] 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 series.

[0088] According to another embodiment, the middle layer 7 and the backing layer 5 can also be formed on an independent shaped wire. When formed on an independent shaped wire, the middle layer 7 and the backing layer 5 are combined in a wet state, and are optionally pressed together before being dried into a double-layer nonwoven sheet, usually using a wet press. Drying can be carried out on a straight-through air dryer. During drying, hydrogen bonds can be formed in the layer.

[0089] The method for producing the wall coating 1 may further comprise a step in which the wall coating 1 is calendered after the coating layer 9 has dried.

[0090] It should be understood that the disclosed embodiments of the present invention are not limited to the specific structures, process steps or materials disclosed herein, but are extended to equivalents that will be recognized by those of ordinary skill in the relevant art. It should also be understood that the terms used herein are only used to describe the purpose of specific embodiments and are not intended to be limiting.

[0091] References throughout this specification to an embodiment or embodiments mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in at least one embodiment of the invention. Thus, the phrases "in one embodiment" or "in an embodiment" appearing in various places in this specification do not necessarily all refer to the same embodiment. When numerical values ​​are referenced using terms such as approximately or substantially, the exact numerical value is also disclosed.

[0092] As used herein, for convenience, multiple items, structural elements, constituent elements and / or materials may appear in a common list. However, these lists should be interpreted as each member in the list being individually identified as a separate and unique member. Therefore, in the absence of contrary instructions, any single member in the list should not be interpreted as the de facto equivalent of any other member in the same list based solely on their appearance in a common group. In addition, various embodiments and examples of the present invention may be mentioned herein together with substitutes of its various components. It should be understood that such embodiments, examples and replacements should not be interpreted as de facto equivalents to each other, but should be regarded as independent and autonomous representations of the present invention.

[0093] In addition, the described features, structures or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, many specific details are provided, such as examples of length, width, shape, etc., to provide a comprehensive understanding of embodiments of the present invention. However, those skilled in the relevant art will recognize that the present invention can be implemented without one or more specific details, or implemented using other methods, components, materials, etc. In other cases, known structures, materials or operations are not shown or described in detail to avoid blurring various aspects of the present invention.

[0094] experiment

[0095] The following test methods were used to obtain the data reported in the following tables.

[0096] Basis Weight: Basis weight is measured according to TAPPI standard T410 and is expressed in grams per square meter (g / m 2 )Report.

[0097] Linear density: Decitex (Dtex) measures the grams per 10,000 meters of fiber or yarn. Dtex is a direct measure of linear density.

[0098] Tear Strength: Tear strength in the longitudinal and transverse directions was measured according to ASTM D-751 pendulum pulse method standard.

[0099] Shrinkage: Shrinkage is measured in the longitudinal and transverse directions according to the W-102 Wall Coatings Association Quality Standard, as described in Sections 7.1.2 and 7.1.3 of the standard. Briefly, three specimens (250mm x 250mm) are measured accurately in each direction to the nearest 0.5mm. The specimens are soaked in distilled water at room temperature for 30 minutes, removed and dried at 87°C for 30 minutes. The specimens are then conditioned for at least 8 hours under the standard conditions specified in ASTM Specification D-751 before being remeasured. The following formula should be used to calculate the shrinkage in each direction:

[0100] % Shrinkage = [(A – B): A] x 100, where A = length before testing and B = length after testing.

[0101] Scrubability: Scrubability was measured according to ASTM F793 standard.

[0102] Luminance and Color Channels: Luminance L, Color Channel a, and Color Channel b are measured according to TAPPI 527 standard.

[0103] Opacity: Opacity is measured according to ISO 2471.

[0104] Toxic gases produced during combustion: Toxic gases produced during combustion of materials are measured according to Boeing Aircraft Standard BSS 7239.

[0105] A wall coating 1 having the following nonwoven substrate layer 3 has been tested. The table below shows the composition of the different layers forming the nonwoven substrate layer 3. It must be noted that the percentages reported in the table below are expressed as percentages in the layers and not as percentages in the entire nonwoven substrate layer 3.

[0106] Table 1. Composition of nonwoven substrate layer 3

[0107] layer Compound raw material Wt% Backing layer Cellulose fiber hardwood 27.5 Backing layer Cellulose fiber cork 44.1 Backing layer Crude synthetic fiber PET, 24mm, 5.5 dtex 6.1 Backing layer Fine synthetic fibers PET, 10mm, 1.7 dtex 21.4 Backing layer Wet strength agent Polyamidoamine epichlorohydrin 0.9 Middle Layer Cellulose fiber Hardwood (Eucalyptus) 75 Middle Layer Cellulose fiber Hardwood (birch) 25

[0108] The dry weight of the backing layer 5 is 144 g / m 2 , and the dry weight of the middle layer 7 is 22g / m 2 As mentioned above, the backing layer 5 and the middle layer 7 are intermixed, that is, the fibers forming the backing layer 5 and the middle layer 7 are intermixed, which enables the backing layer 5 and the middle layer 7 to be well bonded without the need for lamination or adhesives known in the prior art.

[0109] Once dried, the nonwoven substrate layer 3 having the above composition is impregnated with the following binder composition by size pressing.

[0110] Table 2. Binder composition

[0111]

[0112]

[0113] The binder composition used to impregnate the nonwoven substrate layer 3 has a solid content of 33%. In addition, the binder composition used to impregnate the nonwoven substrate layer 3 may further contain some additives, such as pigments, defoamers, wetting agents, curing agents or fluorescent brighteners, either alone or in combination. The nonwoven substrate layer 3 is made of 102 g / m 2 A dry amount of this binder composition is impregnated.

[0114] Once the impregnated nonwoven substrate layer 3 has dried, the nonwoven substrate layer 3 is coated with a coating layer 9 having the following composition.

[0115] Table 3. Composition of coating layer 9

[0116] Compound raw material part filler Calcium carbonate 100 Adhesive Styrene acrylic hydrophobic polymer 25

[0117] The coating layer 9 is 25g / m 2 The dry weight of the wall coating 1 produced, including the impregnated nonwoven substrate layer 3 and the coating layer 9, is 296 g / m 2 .

[0118] The above-mentioned wall coating 1 was tested according to the W-102 wall coating association quality standard. Comparative wall coatings coated with TPO (comparative wall coating 1) and PVC (comparative wall coating 2), both of which meet the Class II requirements defined in the W-102 wall coating association quality standard, were also tested to evaluate the performance of the wall coating 1 of the present invention. The grammage of the comparative TPO-coated wall coating was 339.1 g / m 2 , and the weight of the comparative PVC coated wall coating is 440.8g / m 2 The results obtained are summarized in the following table. Table 4. Test data according to W-102 Wall Coating Association quality standard

[0119]

[0120] As shown in the table above, the wall coating 1 according to the present invention shows improved grab tensile and tensile strength in both the machine direction and the cross direction compared to existing TPO or PVC coated wall coatings. Without being bound by theory, the inventors believe that these improvements are due to the presence of coarse synthetic fibers in the backing layer 5. The wall coating 1 of the present invention is stronger than other existing wall coatings that meet Class II requirements.

[0121] Results of the combustion test

[0122] Furthermore, some fire tests have been carried out on the various wall coatings mentioned above according to Boeing Aircraft Standard BBS 7239 (Fire), and the results are summarized in the following table.

[0123] Table 5. Combustion test according to Boeing Aircraft Standard BBS 7239 (combustion)

[0124]

[0125] Gas Emissions Test Mode

[0126]

[0127] Typically, the wall coating of the present invention exhibits 25% CO emissions compared to a vinyl coated Class II wall coating (Comparative Wall Coating 2) according to the toxicity test of Boeing Aircraft Standard BSS 7239 (Combustion). The results show that the wall coating of the present invention produces 25 ppm CO, while the vinyl coated Class II wall coating exhibits 100 ppm CO in this test.

[0128] In addition, according to the toxicity test of Boeing Aircraft Standard BSS 7239 (non-combustion), the wall coating of the present invention has 50% CO emissions compared to the TPO-coated Type II wall coating (Comparative Wall Coating 1). The results show that the wall coating of the present invention produces 25 ppm of CO, while the TPO-coated Type II wall coating shows 50 ppm of CO in this test.

[0129] Embodiments of the present invention include the following:

[0130] 1. A wall coating (1), comprising:

[0131] - a nonwoven substrate layer (3), said nonwoven substrate layer comprising:

[0132] a backing layer (5); and

[0133] an intermediate layer (7), the intermediate layer being disposed on one side of the backing layer (5); and

[0134] - a coating layer (9), said coating layer being arranged on said intermediate layer (7);

[0135] The backing layer (5) comprises a mixture of cellulose fibers and coarse synthetic fibers, and the coarse synthetic fibers have a linear density of at least 5 dtex.

[0136] 2. The wall coating (1) according to the preceding embodiment, wherein the backing layer (5) comprises a mixture of cellulose fibers, coarse synthetic fibers and fine synthetic fibers.

[0137] 3. The wall coating (1) according to the preceding embodiment, wherein the fine synthetic fibers are present in the backing layer (5) at a level of 15 to 30 wt%, based on the total weight of fibers in the backing layer (5).

[0138] 4. The wall coating (1) according to any one of embodiments 2 or 3, wherein the linear density of the fine synthetic fibers is comprised between 1 dtex and 4 dtex, preferably between 1 dtex and 3.5 dtex.

[0139] 5. The wall coating (1) according to any one of embodiments 2 to 4, wherein the fine synthetic fibers are selected from polyaramid fibers, polyamide fibers, polyester fibers, polyvinyl alcohol fibers, polypropylene fibers, glass fibers and combinations thereof.

[0140] 6. A wall coating (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%, based on the total weight of the fibers in the backing layer (5), preferably in the range of 5 to 30 wt%, more preferably in the range of 5 to 20 wt%.

[0141] 7. The nonwoven material according to any one of the preceding embodiments, wherein the length of the coarse synthetic fibers is at least 12 mm, preferably at least 18 mm.

[0142] 8. The wall coating (1) according to any of the preceding embodiments, wherein the coarse synthetic fibers and the fine synthetic fibers are selected from polyaramid fibers, polyamide fibers, polyester fibers, polyvinyl alcohol fibers, polypropylene fibers, glass fibers and combinations thereof.

[0143] 9. A wall coating (1) according to any one of the preceding embodiments, wherein the 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 fibers in the backing layer (5).

[0144] 10. The wall coating (1) according to any one of the preceding embodiments, wherein the backing layer (5) further comprises a wet strength additive, a dry strength additive or a combination thereof.

[0145] 11. The wall coating (1) according to any one of the preceding embodiments, wherein the basis weight of the backing layer (5) is 130 g / m 2 Up to 160g / m 2 .

[0146] 12. The wall coating (1) according to any one of the preceding embodiments, wherein the intermediate layer (7) comprises cellulose fibers or essentially consists of cellulose fibers.

[0147] 13. A wall coating (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 chemical thermomechanical pulp from hardwood or softwood, bleached or unbleached chemical pulp from hardwood or softwood, and combinations thereof.

[0148] 14. A wall coating (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).

[0149] 15. A wall coating (1) according to the preceding embodiment, wherein the hardwood fibers comprise a mixture 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 the 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.

[0150] 16. The wall coating (1) according to any one of the preceding embodiments, wherein the basis weight of the intermediate layer (7) is 10 g / m 2 Up to 30g / m 2 .

[0151] 17. A wall coating (1) according to any one of the preceding embodiments, wherein fibres from the backing layer (5) and the intermediate layer (7) are mixed at the interface of the layers.

[0152] 18. The wall coating (1) according to any one of the preceding embodiments, wherein the nonwoven substrate layer (3) is impregnated with an impregnation composition.

[0153] 19. The wall coating (1) according to embodiment 18, wherein the impregnation composition comprises a binder, a filler and optional additives.

[0154] 20. The wall coating (1) according to embodiment 19, wherein the binder is selected from styrene acrylate, acrylic acid, latex, ultra-low formaldehyde acrylic acid and combinations thereof.

[0155] 21. The wall coating (1) according to any one of embodiments 19 or 20, wherein the glass transition temperature of the binder is between -25°C and +10°C.

[0156] 22. The wall coating (1) according to any one of embodiments 19 to 21, wherein the filler is selected from kaolin, calcium carbonate, titanium dioxide or a combination thereof.

[0157] 23. The wall coating (1) according to any one of embodiments 18 to 22, wherein the nonwoven substrate layer (3) is made of 80 g / m 2 Up to 120g / m 2 The impregnation is carried out with the impregnation composition in an amount of

[0158] 24. The wall coating (1) according to any one of the preceding embodiments, wherein the coating layer (9) comprises acrylic resin and pigment.

[0159] 25. The wall coating (1) according to the preceding embodiment, wherein the acrylic resin is a hydrophobic styrene acrylic resin.

[0160] 26. The wall coating (1) according to any one of embodiments 24 or 25, wherein the pigment is selected from kaolin, calcium carbonate and mixtures thereof.

[0161] 27. The wall coating (1) according to any one of the preceding embodiments, wherein the coating layer (9) has a thickness of 10 g / m 2 Up to 40g / m 2 The amount of dry weight is coated on the middle layer (7) of the nonwoven substrate layer (3).

[0162] 28. The wall coating (1) according to any one of the preceding embodiments, wherein the wall coating has a basis weight of 250-350 g / m 2 , preferably about 280-320 g / m 2 .

[0163] 29. The wall coating (1) according to any one of the preceding embodiments, wherein the wall coating has a tear strength in the machine direction of at least 25% when measured according to the ASTM D-751 Pendulum Impact Method standard.

[0164] 30. The wall coating (1) according to any one of the preceding embodiments, wherein the wall coating has a tear strength in the transverse direction of at least 25% when measured according to ASTM D-751 - Pendulum Impact Method Standard.

[0165] 31. The wall coating (1) according to any one of the preceding embodiments, wherein the wall coating has a shrinkage in the machine direction of at most 2% when measured according to the W-102 Wall Coating Association quality standard.

[0166] 32. The wall coating (1) according to any one of the preceding embodiments, wherein the wall coating has a shrinkage in the transverse direction of at most 2% when measured according to W-102 Wall Coating Association quality standard.

[0167] 33. The wall coating (1) according to any one of the preceding embodiments, wherein the wall coating has a scrubbability of at least 300 cycles when measured according to ASTM F793 standard.

[0168] 34. A wall coating (1) according to any of the preceding embodiments, wherein the wall coating meets Class II requirements according to the W-102 Wall Coating Association quality standard.

[0169] 35. The wall coating (1) according to any one of the preceding embodiments, wherein, when measured according to TAPPI 527 standard, the wall coating has:

[0170] Lightness L* of at least 90,

[0171] a* for the color channel between -7 and +3, and

[0172] Color channel b* between 2 and 12.

[0173] 36. The wall coating (1) according to any one of the preceding embodiments, wherein the wall coating has a thickness of at least 400 μm.

[0174] 37. The wall coating (1) according to any one of the preceding embodiments, wherein the wall coating has an opacity of at least 90%, preferably at least 95%, when measured according to ISO 2471 standard.

[0175] 38. The wall coating (1) according to any one of the preceding embodiments, wherein the coating layer (9) is printed.

[0176] 39. A wall coating according to any of the preceding embodiments, wherein the printed side (11) of the coating layer (9) is printed, the printed side (11) being arranged on the side of the coating layer (9) opposite to the side in contact with the intermediate layer (7).

[0177] 40. A method for producing a wall coating (1), comprising the following steps:

[0178] - forming an intermediate layer (7) during wet-laying;

[0179] - forming a backing layer (5) during wet-laying;

[0180] - drying the layers to obtain a continuous two-layer nonwoven sheet;

[0181] - impregnating the dried double-layer nonwoven sheet by applying a binder composition that penetrates into both sides of the double-layer nonwoven sheet;

[0182] - drying the double-layer nonwoven sheet treated with the binder to form a nonwoven substrate layer (3); and

[0183] - applying a coating layer (9) on top of the intermediate layer (7) of the nonwoven substrate layer (3) obtained;

[0184] The backing layer (5) of the nonwoven substrate layer (3) comprises a mixture of cellulose fibers and coarse synthetic fibers, and the coarse synthetic fibers have a linear density of at least 5 dtex.

[0185] 41. The method according to embodiment 40, wherein the backing layer (5) and the intermediate layer (7) are formed on the same shaped wire.

[0186] 42. The method according to embodiment 40, wherein the backing layer (5) and the intermediate layer (7) are formed on separate forming wires, combined in a wet state, and optionally pressed together before being dried into one nonwoven sheet on a straight-through air dryer.

[0187] 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 double-layer nonwoven sheet.

[0188] 44. The method according to any one of embodiments 40 to 43, wherein the nonwoven web is calendered after the step of applying the coating layer (9).

[0189] 45. Use of a wall coating according to any one of embodiments 1 to 39 on the surface of an interior wall of a building, preferably in the medium wear area according to the W-102 Wall Coating Association quality standard.

[0190] 46. ​​A method of protecting the surface of an interior wall of a building with a wall coating according to any one of Examples 1 to 39 in the moderate wear area according to the W-102 Wall Coating Association quality standard.

[0191] Although the foregoing examples illustrate the principles of the present invention in one or more specific applications, it is obvious to those skilled in the art that various modifications can be made in form, use and implementation details without using creativity and without departing from the principles and concepts of the present invention. Therefore, except for the claims set forth herein, it is not intended to limit the present invention.

[0192] The verbs "to comprise" and "to include" are used in this document as open limitations that neither exclude nor require the presence of unrecited features. The features recited in the dependent claims may be freely combined with each other unless expressly stated otherwise. Furthermore, it should be understood that the use of "a" or "an" throughout this document, i.e. in the singular, does not exclude a plurality.

[0193] Industrial Applicability

[0194] The present technology can be used to manufacture wall coatings that meet the Class II requirements set for wall coatings intended for use in areas of moderate wear and tear. The wall coatings can be used as conventional wallpapers for decoration in homes and public places.

[0195] Citation List

[0196] [Patent Document]

[0197] US 2005 / 0014431

[0198] CN112318955A

Claims

1. A wall coating (1), comprising: A nonwoven substrate layer (3), the nonwoven substrate layer comprising: a backing layer (5); and an intermediate layer (7), the intermediate layer being disposed on one side of the backing layer (5); and A coating layer (9), the coating layer being arranged on the intermediate layer (7); The backing layer (5) comprises a mixture of cellulose fibers and coarse synthetic fibers, and the coarse synthetic fibers have a linear density of at least 5 dtex.

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

3. The wall coating (1) according to claim 1, wherein: The coarse synthetic fibers are present in the backing layer (5) at a level of at least 5 wt%, based on the total weight of fibers in the backing layer (5).

4. The wall coating (1) according to claim 1, wherein: The cellulosic fibers are present in the backing layer (5) at a level of at least 50 wt%, based on the total weight of fibers in the backing layer (5).

5. The wall coating (1) according to claim 1, wherein: The intermediate layer (7) comprises or consists essentially of cellulose fibers.

6. The wall coating (1) according to claim 1, wherein: The middle 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 middle layer (7).

7. The wall coating (1) according to claim 6, wherein: The hardwood fibers include a mixture of eucalyptus fibers and birch fibers.

8. The wall coating (1) according to claim 1, wherein: The nonwoven substrate layer (3) is impregnated with an impregnation composition comprising a binder, a filler and optional additives.

9. The wall coating (1) according to claim 8, wherein: The binder is selected from styrene acrylate, acrylic acid, latex, ultra-low formaldehyde acrylic acid and combinations thereof.

10. The wall coating (1) according to claim 1, wherein: The coating layer (9) comprises acrylic resin and pigment.

11. The wall coating (1) according to claim 1, wherein: The basis weight of the wall coating is 250-350g / m 2 .

12. The wall coating (1) according to claim 1, wherein: The wall coating has a tear strength in the machine direction of at least 25% when measured according to the ASTM D-751 Pendulum Impact Method standard.

13. The wall coating (1) according to claim 1, wherein: The wall coating has a tear strength in the cross direction of at least 25% when measured according to ASTM D-751 - Pendulum Impact Method Standard.

14. The wall coating (1) according to claim 1, wherein: The wall coating has a shrinkage in the machine direction of at most 2% when measured according to W-102 Wall Coating Association quality standard.

15. The wall coating (1) according to claim 1, wherein: The wall coating has a shrinkage in the cross direction of at most 2% when measured according to W-102 Wall Coating Association quality standard.

16. The wall coating (1) according to claim 1, wherein: The wall coating has a scrubbability of at least 300 cycles when measured according to ASTM F793 standard.

17. The wall coating according to claim 1, wherein: The printed side (11) of the coating layer (9) is printed, and the printed side (11) is arranged on the side of the coating layer (9) opposite to the side contacting the intermediate layer (7).

18. A method for producing a wall coating (1), comprising the following steps: forming an intermediate layer (7) during the wet-laid web forming process; forming a backing layer (5) during a wet-laid web forming process; drying the layers to obtain a continuous two-layer nonwoven sheet; impregnating the dried double-layer nonwoven sheet by applying a binder composition that permeates into both sides of the double-layer nonwoven sheet; Drying the double-layer nonwoven sheet treated with the binder to form a nonwoven substrate layer (3); as well as applying a coating layer (9) on top of the intermediate layer (7) of the obtained nonwoven substrate layer (3); The backing layer (5) of the nonwoven substrate layer (3) comprises a mixture of cellulose fibers and coarse synthetic fibers, and the coarse synthetic fibers have a linear density of at least 5 dtex.

19. The method according to claim 18, wherein: The nonwoven web is calendered after the step of applying the coating layer (9).

20. Use of the wall coating according to claim 1 on the surface of the inner wall of a building.

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