Cellulose-based VOC barrier

Abstract

The present disclosure relates to a layered assembly comprising a cellulose-based layer that is impermeable to VOC; a method of blocking VOC using a cellulose-based layer that is impermeable to VOC; and a method of making a layered assembly comprising a VOC impermeable cellulose-based layer.

Description

(19) State Intellectual Property Office (12) Invention Patent Application (10) Application Publication Number (43) Application Publication Date (21) Application Number 202480043650.6 (22) Application Date 2024.04.30 (30) Priority Data 23171058.3 2023.05.02 EP (85) PCT International Application Entering National Phase Date 2025.12.27 (86) PCT International Application Application Data PCT / EP2024 / 061906 2024.04.30 (87) PCT International Application Publication Data WO2024 / 227786 EN 2024.11.07 (71) Applicant Auslon Company Address Finland (72) Inventor Benoît Moro, Olivier Paquet (74) Patent Agency Beijing Pinyuan Patent Agency Co., Ltd. 11332 Patent Attorney Liu Minghai Hu Bin (51) Int.Cl. B32B 29 / 00 (2006.01) B32B 7 / 12 (2006.01) B32B 21 / 02 (2006.01) B32B 21 / 04 (2006.01) B32B 21 / 06 (2006.01) B32B 7 / 08 (2019.01) (54) Invention Title Cellulose-Based VOC Barrier (57) Abstract This disclosure relates to a layered assembly comprising a cellulose-based layer impermeable to VOCs; a method for blocking VOCs using the cellulose-based layer impermeable to VOCs; and a method for preparing a layered assembly comprising a cellulose-based layer impermeable to VOCs. Claims 2 pages, Description 14 pages, Drawings 2 pages, CN 121443448 A 2026.01.30 CN 1 21 44 34 48 A 1. A layered assembly comprising a substrate and a cellulose-based layer disposed on the substrate; wherein the cellulose-based layer has a thickness of at least 20 µm, preferably at least 30 µm, and more preferably at least 40 µm, and a density of at least 800 kg / m³; wherein the cellulose-based layer covers at least one surface of the substrate; wherein the substrate contains at least one emitter of volatile organic compounds (VOCs); and wherein the cellulose-based layer is substantially impermeable to the VOCs. 2. The layered assembly according to claim 1, wherein the cellulose-based layer comprises a continuous cellulose fiber matrix, the continuous cellulose fiber matrix comprising natural cellulose fibers and insoluble cellulose material.3. The layered assembly according to any one of the preceding claims, wherein, when measured according to the specification, the content of the insoluble cellulose material in the continuous cellulose fiber matrix is ​​from 10 wt% to 60 wt%, more preferably from 15 wt% to 55 wt%. 4. The layered assembly according to any one of the preceding claims, wherein, when measured according to the specification, the cellulose-based layer has a VOC transmission flux of at most 1.5E-04 mg / (cm²·hr). 5. The layered assembly according to any one of the preceding claims, wherein, when calculated according to formula (1), the layered assembly has a VOC transmission reduction (X) of at least 50%, preferably at least 65%: (1) where Y is the reduced VOC transmission, and Y0 is the VOC emission, wherein Y and Y0 are measured according to the specification. 6. The layered assembly according to any one of the preceding claims, wherein the VOC is any one of the following: formaldehyde, acetaldehyde, benzaldehyde, pentanal, 3-carene, nonanal, pinene, terpene, hexanal, butyraldehyde, acetone, and / or dichloromethane, preferably formaldehyde. 7. The layered assembly according to any one of the preceding claims, wherein the substrate comprises a natural fiber-based material and / or a wood-based material and / or a resin-impregnated material. 8. The layered assembly according to any one of the preceding claims, wherein the substrate is a building structure; such as a laminated paper structure, barrier panel, ceiling panel, fiber-based barrier material, gypsum board, solid wood board, particleboard, perlite board, medium-density fiberboard (MDF), high-density fiberboard (HDF), oriented strand board (OSB), plywood, or wood-plastic composite (WPC) board. 9. The layered assembly according to any one of the preceding claims, wherein the cellulose-based layer is in contact with the substrate at the covered surface. 10. A method for blocking VOCs using a cellulose-based layer, wherein the cellulose-based layer has a thickness of at least 20 µm, preferably at least 30 µm, and more preferably at least 40 µm, and a density of at least 800 kg / m³, and wherein the cellulose-based layer is substantially impermeable to at least one VOC, preferably in a layered assembly. 11. A method for preparing a layered assembly according to any one of claims 1 to 9, wherein the method comprises disposing the cellulose-based layer on a substrate by any of the following: pressing, laminating, gluing, impregnating, binding, stapled, adhesive, coating.12. The method of claim 11, wherein the method comprises preparing the cellulose-based layer by means of: (i) providing a cellulose fiber layer precursor comprising natural cellulose fibers, (ii) subjecting the cellulose fiber layer precursor to a cellulose dissolution step to produce a treated cellulose fiber layer comprising dissolved cellulose, and (iii) subjecting the treated cellulose fiber layer to a reprecipitation step in which the dissolved cellulose is reprecipitated. 13. The method of claim 12, wherein the cellulose dissolution step comprises contacting the cellulose fiber layer precursor with a gelling agent, thereby subjecting the cellulose fiber layer precursor to a reaction with the gelling agent to dissolve the natural cellulose fibers, thereby producing a treated cellulose fiber layer, and wherein the reprecipitation step comprises subjecting the treated cellulose fiber layer to a reprecipitant. 14. The method of claim 11, wherein the method comprises preparing the cellulose-based layer by a wet web forming process comprising a refining step and / or calendering, preferably supercalendering. Claims 2 / 2 Page 3 CN 121443448 A Cellulose-based VOC Barrier Technology

[0001] This disclosure relates to a layered assembly comprising a cellulose-based layer impermeable to VOCs; a method for blocking VOCs using the cellulose-based layer impermeable to VOCs; and a method for preparing a layered assembly comprising a cellulose-based layer impermeable to VOCs. Background Art

[0002] Indoor air pollution is a key factor contributing to health risks ranging from skin, eye, nose, and throat irritation to organ damage and cancer. The most significant of these pollutants are volatile organic compounds (VOCs), which can be emitted from various indoor sources such as furniture, paint, and building materials. Emitted VOCs can come into contact with the occupant's body through inhalation or absorption into mucous membranes.

[0003] Formaldehyde, as a specific VOC, is a colorless, flammable gas with a strong odor at room temperature and can cause skin, eye, nose, and throat irritation. Furthermore, formaldehyde is suspected to be a carcinogen. Formaldehyde emitters can include many products, such as resins in plywood, furniture and boards, building materials and barrier materials, adhesives, paints, varnishes, etc. VOCs have also been identified as being associated with the so-called “sick building syndrome,” which is a collective term for the acute health and comfort effects experienced by residents.

[0004] To date, efforts to reduce VOC concentrations in indoor spaces have focused on the preparation of furniture and / or building materials with lower VOC emissions and gas releases, improving ventilation in indoor spaces, and adding VOC scavengers (such as primary and secondary amines, borax, and sodium sulfite).

[0005] Typically, these methods can only provide intermittent relief and / or they may require complex and expensive processing steps. Additionally, the use of chemical cleaners and / or plastic coverings may not be environmentally friendly because the required materials are not biologically derived. Summary of the Invention

[0006] The present invention addresses the problems of the prior art in the following ways.

[0007] In a first aspect, the present invention relates to a layered assembly comprising a substrate and a cellulose-based layer disposed on the substrate; wherein the cellulose-based layer has a thickness of at least 20 µm, preferably at least 30 µm, and more preferably at least 40 µm, and a density of at least 800 kg / m³; wherein the cellulose-based layer covers at least one surface of the substrate; wherein the substrate contains at least one emitter of volatile organic compounds (VOCs); and wherein the cellulose-based layer is substantially impermeable to the VOCs.

[0008] In a second aspect, the present invention relates to a method for blocking VOCs using a cellulose-based layer, wherein the cellulose-based layer has a thickness of at least 20 µm, preferably at least 30 µm, and more preferably at least 40 µm, and a density of at least 800 kg / m³, and wherein the cellulose-based layer is substantially impermeable to at least one VOC, preferably in a layered assembly.

[0009] In a third aspect, the present invention relates to a method for preparing a layered assembly according to the first aspect, wherein the method comprises configuring the cellulose-based layer on the substrate by any of the following: pressing, laminating, gluing, impregnating, binding, stapled, adhesive, coating. Specification 1 / 14 pages 4 CN 121443448 A Brief Description of the Drawings

[0010] Figure 1 depicts a bar chart showing the measurement results of undissolved cellulose content in different types of parenchyma samples.

[0011] Figure 2 illustrates the experimental setup for measuring the formaldehyde transport flux of Example 2.

[0012] (1): Formaldehyde storage tank

[0013] (2): Sample

[0014] (3): Air inlet

[0015] (4): Air outlet

[0016] (5): Sealed container

[0017] (6): Water trap

[0018] Figure 3 illustrates the results of formaldehyde transport flux as a function of the content of insoluble materials.

[0019] (A) Parchment A - Low parchmentation

[0020] (B) Parchment B - Medium parchmentation

[0021] (C) Parchment C - Medium to high parchmentation

[0022] (D) Parchment D - Very high parchmentation Detailed Description

[0023] Layered Assembly

[0024] In a first aspect, the present invention relates to a layered assembly comprising a substrate and a cellulose-based layer disposed on the substrate; wherein the cellulose-based layer has a thickness of at least 20 µm, preferably at least 30 µm, and more preferably at least 40 µm, and a density of at least 800 kg / m³; wherein the cellulose-based layer covers at least one surface of the substrate; wherein the substrate contains at least one emitter of volatile organic compounds (VOCs); and wherein the cellulose-based layer is substantially impermeable to the VOCs.

[0025] The term "cellulose-based" describes a substrate and / or material and / or article that primarily comprises cellulose. The material may be a fiber or a film. Cellulose materials are derived from man-made sources, such as regenerated cellulose fibers or films, or from natural sources, such as fibers or pulp from woody or non-woody plants. Cellulose-based materials can comprise woven or nonwoven cellulose. Nonwoven cellulose-based materials can be formed by a number of processes, such as spinning, carding, air-forming, and wet-forming processes. The basis weight of cellulose-based materials is typically expressed as weight per unit area, for example in grams per square meter (gsm = g / m2) or ounces per square foot (osf). Cellulose-based materials can comprise natural cellulose fibers and / or insoluble cellulose materials.

[0026] As used herein, the term “fiber” refers to a form of material characterized by an extremely high length-to-diameter ratio. Typically, cellulose fibers have a very wide range of diameters and lengths, depending on the fiber type and its source. The average length of the wood pulp fibers preferably used in this invention is typically in the range of 0.3 mm to 3.5 mm, preferably 0.3 mm to 3.0 mm, more preferably 0.8 mm to 2.5 mm, and even more preferably 1.0 mm to 2.0 mm. The diameter of the wood pulp fibers is typically in the range of 10 µm to 40 µm, preferably 15 µm to 35 µm, and even more preferably 20 µm to 30 µm. Therefore, the aspect ratio (the ratio of fiber length to fiber diameter) of the wood pulp fibers is typically in the range of 7.5 to 350, preferably 7.5 to 300, more preferably 10 to 200, and even more preferably 20 to 150. Unless otherwise specified, the terms "fiber" and "filament" are used interchangeably for the purposes of this invention.

[0027] The term "natural cellulose fiber" refers to cellulose fibers derived from natural sources such as: woody plants, including deciduous and coniferous trees; or non-woody plants, including cotton, flax, reeds, kenaf, sisal, abaca, milkweed, rice straw, jute, hemp, and bagasse. Preferably, natural cellulose fibers are suitable for dissolving with a gelling agent. For example, fibers suitable for dissolving are, for example, hardwood fibers, softwood fibers, or annual plant fibers. Natural cellulose fibers form partially crystalline materials comprising crystalline fractions, wherein the crystalline form of cellulose I comprises all parallel-oriented cellulose chains.

[0028] The term "insoluble cellulose material" specifies a material obtained by subjecting natural cellulose fibers to a reaction with a gelling agent, thereby at least partially dissolving the natural cellulose fibers, wherein the natural cellulose fibers are partially dissolved and the dissolved fractions form a gel-like viscous material, and the gelling agent is subsequently removed by washing with a redeposition agent, thereby precipitating the gel-like material to form a solid material. Such insoluble cellulose materials comprise non-cellulose material forming a gel and some fibers trapped within the gel, which are inaccessible to the gelling agent. As specified in Example 1, if the material is insoluble in a solution of 0.5 mol (M) copper-ethylenediamine (CED) in water, then the material is designated as "insoluble". A process of dissolving natural cellulose fibers and redepositioning them is called a paring process. The solid material referred to herein as insoluble cellulose material may comprise other forms of crystalline fractions, such as crystalline fractions having the cellulose II crystal form comprising antiparallel cellulose chains. Insoluble cellulose material is preferably a redepositioned gelled cellulose material and natural fibers trapped within the gel.

[0029] As used herein, the term “volatile organic compound” (VOC) refers to an organic compound or fraction of creosote oil that has a high vapor pressure at room temperature. In one embodiment, under specific conditions of use, the VOC may have a vapor pressure of 0.01 kPa or higher at 293.15 K. VOCs can be emitted from wood-based materials, resins, paints, varnishes, etc., which may be contained in furniture or building materials. Exposure to VOCs (e.g., through inhalation or through mucous membranes) can cause a number of health problems, including nausea, irritation of the eyes, nose and throat, irritation of the lungs and bronchi, and dizziness.

[0030] As used herein, the term “VOC emitter” refers to an article or material capable of releasing VOCs at room temperature and pressure. Unless otherwise stated, the VOC may be referred to as “VOC emitter” or more simply as “VOC”. Unless otherwise stated, the VOC emitter is also simply referred to herein as “emitter”. When the emitter is contained in a substrate, the emitter is capable of releasing VOCs from the substrate at room temperature and pressure.

[0031] The emitter may be capable of releasing more than one VOC at room temperature and pressure. For example, in one embodiment, the emitter may be capable of releasing VOC A and VOC B at room temperature and pressure. In one embodiment, the emitter may be capable of releasing multiple VOCs at room temperature and pressure. Similarly, the substrate may contain emitters of more than one VOC. When the substrate contains more than one emitter, the emitters need not be capable of releasing the same VOC. For example, the substrate may contain emitter 1 and emitter 2, wherein emitter 1 is capable of releasing VOC A and VOC B at room temperature and pressure. Emitter 2 may be capable of releasing VOC A and VOC B at room temperature and pressure, or releasing VOC B and VOC C at room temperature and pressure, or releasing VOC C and VOC D or others at room temperature and pressure.

[0032] In one embodiment, the emitter has VOC emissions above a detection threshold or peak VOC emissions. When the emitter is contained in a substrate, the substrate typically has VOC emissions above a detection threshold or peak VOC emissions.

[0033] As used herein, the term “emission” means a certain amount of gas emitted from a source within a specified time period. As used herein, the term “VOC emission” means an emission in which the gas is a VOC. When more than one VOC is emitted, the VOC emission can be the sum of the individual VOC emissions. Unless otherwise specified, the emitted gas is a VOC herein. An emission can be characterized with respect to a specific surface area of ​​the source, a specific mass of the source, a specific volume of the source, or otherwise. If the emission is characterized with respect to a specific surface area of ​​the source, it is referred to herein as an “emission flux.” Specifically, the term “emission flux” can be defined as [amount of gas] / ([surface area] × [time]), where [surface area] is the surface area of ​​the source. If the emission is characterized with respect to a specific mass of the source, it can be expressed as [amount of gas] / ([mass] × [time]), where [mass] is the mass of the source. If emissions are characterized for a specific volume of the source, they can be expressed as [amount of gas] / ([volume] × [time]), where [volume] is the volume of the source. In this paper, the substrate is typically the source due to the emissions contained therein. That is, when the substrate has a surface area of ​​(SA) cm² and emits (e) mg of gas (g) over a time span of (t) hours, then the (g) emission flux characterized for a specific surface area of ​​the substrate is given by (e) / [(t) hr × (SA) cm²]. Similarly, when the substrate has a mass of (m) kg, then the (g) emission characterized for a specific mass is given by (e) / [(t) hr × (m) kg].Similarly, when the substrate has a volume of (v), then the (g) emission, characterized for a specific mass, is given by (e) / [(t)hr × (v) cm3].

[0034] Emission bodies typically have VOC emissions above the detection threshold. When an emission body is contained in a substrate, the substrate typically has VOC emissions above the detection threshold.

[0035] However, it is well known that VOC emissions from an emission body may decrease over time as VOCs or substances that generate VOCs are depleted from the emission body. For example, wood-based materials may initially have high VOC emissions after major processing steps such as felling trees, cutting boards, hot pressing, gluing, etc. Over time, such emissions typically decrease, potentially falling below the detection limit. Such wood-based materials are capable of releasing VOCs at room temperature and pressure. Due to this change over time, an emission body can also be characterized by its peak VOC emissions closely recorded after the major processing steps of the substrate. Therefore, an emission body may have peak VOC emissions. When the emitter is contained within a substrate, the substrate typically has peak VOC emissions. The term “peak VOC emissions” may also be referred to as “early lifetime VOC emissions.” In one embodiment, peak emissions may be measured within 5 years, 4 years, 3 years, 2 years, 1 year, 6 months, 3 months, 1 month, or 1 week after the main processing step.

[0036] In a preferred embodiment, the emitter has spontaneous VOC emissions above a detection threshold or spontaneous peak VOC emissions. When the emitter is contained within a substrate, the substrate typically has spontaneous VOC emissions above a detection threshold or spontaneous peak VOC emissions.

[0037] If VOC emissions occur spontaneously under environmental conditions, i.e., without further energy input or manipulation, then the VOC emissions are “spontaneous.” “Further energy input or manipulation” may include operations that are destructive to the substrate and will thereby increase its VOC emissions, such as combustion, crushing, drilling, pulping, sawing, etc. Environmental conditions may include room temperature, pressure, humidity, etc., which are expected in normal climates and the home environment. For example, in one embodiment, environmental conditions may include a temperature range of 10°C to 35°C, preferably 18°C ​​to 23°C, at atmospheric pressure. Environmental conditions may also include local temperature and humidity fluctuations expected in normal climates and the home environment. Such variations may include localized heating due to sunlight exposure and sudden humidity changes, such as those caused by condensation.

[0038] In a preferred embodiment, the emitter has spontaneous VOC emissions or spontaneous peak VOC emissions of at least 0.5 µg / m³.Similarly, the substrate may have spontaneous VOC emissions or spontaneous peak VOC emissions of at least 1.0 µg / m3. Preferably, the spontaneous VOC emissions and / or spontaneous peak VOC emissions of the emitter and / or substrate are at least 5.0 µg / m3, more preferably at least 10.0 µg / m3, more preferably at least 30.0 µg / m3, more preferably at least 50.0 µg / m3, more preferably at least 100.0 µg / m3, more preferably at least 500.0 µg / m3, more preferably at least 1000.0 µg / m3, and more preferably at least 2000.0 µg / m3.

[0039] In a preferred embodiment, the VOC is formaldehyde, and the spontaneous formaldehyde emissions and / or spontaneous peak formaldehyde emissions of the emitter and / or substrate, as determined according to EN 717-7, are at least 0.5 µg / m3. Preferably, the spontaneous formaldehyde emission and / or spontaneous peak formaldehyde emission of the emitter and / or substrate is at least 1.0 µg / m3, more preferably at least 5.0 µg / m3, more preferably at least 10.0 µg / m3, more preferably at least 30.0 µg / m3, more preferably at least 50.0 µg / m3, more preferably at least 100.0 µg / m3, more preferably at least 500.0 µg / m3, more preferably at least 1000.0 µg / m3, and even more preferably at least 2000.0 µg / m3, as stated on page 4 / 14 of the specification (CN 121443448 A).

[0040] Unless otherwise stated, the cellulose-based layer that is substantially impermeable to VOCs may also be referred to herein as a “cellulose-based layer impermeable to VOCs” or simply as a “cellulose-based layer”.

[0041] The cellulose-based layer has a thickness of at least 20 µm. Preferably, the cellulose-based layer has a thickness of at least 30µm, more preferably at least 40µm, more preferably at least 50µm, more preferably at least 60µm, more preferably at least 70µm, more preferably at least 80µm, more preferably at least 90µm, more preferably at least 100µm, more preferably at least 110µm, more preferably at least 120µm, more preferably at least 130µm, more preferably at least 140µm, more preferably at least 150µm, more preferably at least 160µm, more preferably at least 170µm, more preferably at least 180µm, more preferably at least 190µm, and even more preferably at least 200µm.

[0042] In one embodiment, the cellulose-based layer has a thickness of up to 1.00 mm, preferably up to 0.8 mm, more preferably up to 0.6 mm, more preferably up to 0.5 mm, more preferably up to 0.4 mm, more preferably up to 0.35 mm, more preferably up to 0.3 mm, and even more preferably up to 0.25 mm.

[0043] The cellulose-based layer has a density of at least 800 kg / m³. Preferably, the cellulose-based layer has a density of at least 850 kg / m³, more preferably at least 900 kg / m³, even more preferably at least 950 kg / m³, and even more preferably at least 1000 kg / m³. The density can be determined by ISO 534.

[0044] The cellulose-based layer is substantially impermeable to the VOCs of the emission. When the emission is capable of emitting more than one VOC at room temperature and pressure, the cellulose-based layer is substantially impermeable to at least one VOC of the emission. In one embodiment, the cellulose-based layer is substantially impermeable to substantially all VOCs of the emission. As used herein, the term "impermeability" is defined as the quality of a material or article that allows only a small fraction of molecules to permeate through it. The term can also be understood as the quality of a material or article that can significantly reduce the transmission of VOCs through it.

[0045] The cellulose-based layer covers at least one surface of the substrate. At least one surface of the substrate that is covered is referred to herein as the "covered surface". The surface of the layered assembly is the interface between the layered assembly and the surrounding environment. At the covered surface, the surface of the layered assembly cannot be the surface of the substrate because the cellulose-based layer is interposed between the covered surface and the surrounding environment. By being impermeable to VOCs and covering at least one surface of the substrate, the cellulose-based layer blocks the surrounding environment from the VOCs at the covered surface. As referred to herein, the term "VOC-blocking" or "VOC-blocking" means the ability of a material or article to significantly reduce VOC transmission through the material, thereby resulting in a net reduction in VOC concentration within a given volume compared to the absence of the material or article.

[0046] In one exemplary embodiment, the layered assembly is a furniture article (such as a wardrobe) comprising a wood-based frame as a substrate, which is covered by a cellulose-based layer that is impermeable to VOCs. The wood-based material contained in the frame emits VOCs from the frame, but the VOCs cannot permeate the cellulose-based layer. The surrounding environment includes the home space near the wardrobe, such as the room where the wardrobe is placed. Therefore, the cellulose-based layer blocks VOC emissions from the room, meaning that if the cellulose-based layer does not cover the substrate, the VOC concentration in the room will be higher.

[0047] In one embodiment, the cellulose-based layer has a basis weight of at least 30 gsm, preferably at least 40 gsm, more preferably at least 45 gsm, more preferably at least 50 gsm, more preferably at least 55 gsm, more preferably at least 60 gsm, and even more preferably at least 65 gsm. The basis weight can be measured according to ISO 536.

[0048] In one embodiment, the cellulose-based layer comprises tracking paper or high-density paper.In one embodiment, the cellulose-based layer consists of tracer paper or high-density paper.

[0049] In a preferred embodiment of the first aspect of the invention, the cellulose-based layer comprises a continuous cellulose fiber matrix, which comprises natural cellulose fibers and insoluble cellulose material.

[0050] As used herein, the term "continuous cellulose fiber matrix" refers to a cellulose material comprising natural cellulose fibers and insoluble cellulose material, wherein the natural cellulose fibers are embedded in the insoluble cellulose material, thereby blocking the pores of the fiber skeleton. Thus, the continuous cellulose fiber matrix represents a dense material that provides a cellulose continuity between the natural cellulose fibers and the insoluble cellulose material, thereby reducing the voids at the interface between the natural cellulose fibers and the insoluble cellulose material. Thus, the continuous cellulose fiber matrix is ​​a continuous material with reduced porosity. Preferably, the continuous cellulose fiber matrix is ​​non-porous. The continuous cellulose fiber matrix can have high gas barrier properties, especially against VOCs. In a preferred embodiment, the continuous cellulose fiber matrix is ​​substantially impermeable to at least one VOC. Not wanting to be bound by theory, the inventors believe that cellulose-based layers comprising a continuous cellulose fiber matrix and thickness and density requirements have a fairly high barrier property against VOCs (such as formaldehyde) because VOC molecules cannot penetrate the dense, continuous cellulose fiber matrix with reduced porosity.

[0051] In one embodiment, the continuous cellulose fiber matrix further comprises destructured cellulose fibers. The expression "destructured cellulose fibers" describes the periphery of natural cellulose fibers that have been partially dissolved with a gelling agent, thereby creating a gradual structural change from natural cellulose to precipitated cellulose. Such a gradual structural change means that the structure of the continuous cellulose fiber matrix contains a structural gradient, wherein the crystalline structure of the natural cellulose fibers slowly transforms into a largely amorphous structure of the insoluble cellulose material by forming destructured cellulose fibers on the surface of the natural cellulose fibers. Thus, the destructured cellulose fibers surround the natural cellulose fibers and are inserted between the natural cellulose fibers and the insoluble cellulose material. Preferably, the continuous cellulose fiber matrix may consist of natural cellulose fibers, destructured cellulose fibers, and insoluble cellulose material.

[0052] In one embodiment, the cellulose-based layer comprises at least 50 wt% of a continuous cellulose fiber matrix.Preferably, the cellulose-based layer comprises at least 55 wt% of a continuous cellulose fiber matrix, more preferably at least 60 wt% of a continuous cellulose fiber matrix, more preferably at least 65 wt% of a continuous cellulose fiber matrix, more preferably at least 70 wt% of a continuous cellulose fiber matrix, more preferably at least 75 wt% of a continuous cellulose fiber matrix, more preferably at least 80 wt% of a continuous cellulose fiber matrix, more preferably at least 85 wt% of a continuous cellulose fiber matrix, more preferably at least 90 wt% of a continuous cellulose fiber matrix, more preferably at least 95 wt% of a continuous cellulose fiber matrix, and even more preferably at least 99 wt% of a continuous cellulose fiber matrix. In one embodiment, the cellulose-based layer is substantially composed of a continuous cellulose fiber matrix. In one embodiment, the cellulose-based layer is composed of a continuous cellulose fiber matrix.

[0053] In a preferred embodiment of the first aspect of this application, the content of insoluble cellulose material in the continuous cellulose fiber matrix is ​​from 10 wt% to 60 wt%. The content of insoluble cellulose material is measured as described in Example 1. In one embodiment, the content of insoluble cellulose material in the continuous cellulose fiber matrix is ​​12 wt% to 58 wt%, more preferably 14 wt% to 56 wt%, more preferably 16 wt% to 54 wt%, more preferably 18 wt% to 52 wt%, more preferably 20 wt% to 50 wt%, more preferably 22 wt% to 50 wt%, and even more preferably 24 wt% to 50 wt%. Not wishing to be bound by theory, the inventors believe that a continuous cellulose fiber matrix containing 10-60 wt% insoluble cellulose material, along with a cellulose-based layer requiring specific thickness and density, exhibits particularly high barrier properties against VOCs (such as formaldehyde) because VOC molecules cannot penetrate the dense, continuous cellulose fiber matrix with reduced porosity. When the insoluble cellulose material content in the continuous cellulose fiber matrix is ​​below 10%, the continuous cellulose fiber matrix may be too porous and / or insufficiently dense, thus failing to achieve particularly high barrier properties. When the insoluble cellulose material in a continuous cellulose fiber matrix exceeds 60%, the continuous cellulose fiber matrix may be brittle, leading to cracks in the continuous cellulose fiber matrix.

[0054] In a preferred embodiment of the first aspect of the invention, the cellulose-based layer has a VOC transport flux of up to 1.5E-04 mg / (cm²·hr). Preferably, the cellulose-based layer has a VOC transport flux of up to 1.5E-05 mg / (cm²·hr), and more preferably, the cellulose-based layer has a VOC transport flux of up to 1.5E-06 mg / (cm²·hr).

[0055] As used herein, the term “transmission” refers to a certain amount of gas that is transmitted through a membrane within a specified time period. As used herein, a “membrane” can be an article made of a material through which gas can be transmitted. As used herein, the term “VOC transmission” refers to the transmission of a gas that is a VOC. When more than one VOC is transmitted, VOC transmission is the sum of the individual VOC transmissions. Unless otherwise specified, the gas transmitted herein is a VOC. Transmission can be characterized with respect to a specific surface area of ​​the membrane. If transmission is characterized with respect to a specific surface area of ​​the membrane, it is referred to herein as “transmission flux”. Specifically, transmission flux can be defined as [amount of gas] / ([surface area] × [time]), where surface area refers to the surface area of ​​the membrane through which transmission occurs. In this document, transmission flux is typically specified with respect to a specific gas and a specific material and membrane thickness. In other words, the VOC transport flux of a material (pad) with a thickness of (th) is (tf) cm3 / [cm2 × day], meaning that (tf) cm3 of VOC per cm2 of membrane surface area per day is transported through the membrane and thickness (th) of the material (pad).

[0056] As used herein, VOC transport flux can be used to characterize the VOC barrier properties of a material. For example, when the material is a cellulose-based layer, the VOC transport flux of the cellulose-based layer can characterize the VOC barrier properties of the cellulose-based layer. In other words, if the VOC transport flux of a material (pad) of a given thickness is high, a large amount of VOC will pass through the membrane of the material, and the material has low VOC barrier properties. Similarly, if the VOC transport flux is low, then the formaldehyde barrier properties are high.

[0057] VOC transport flux can be measured as described in Example 2.

[0058] In a preferred embodiment, the VOC is formaldehyde, and the VOC transport flux is the formaldehyde transport flux.

[0059] In a preferred embodiment of the first aspect of the invention, when calculated according to formula (1), the layered assembly has a VOC transmission reduction (X) of at least 50%:

[0060] (1)

[0061] where Y is the reduced VOC transmission and Y0 is the VOC emission. Preferably, the VOC transmission reduction is at least 60%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, more preferably at least 90%, more preferably at least 95%, and even more preferably at least 98%.

[0062] “Reduced VOC transmission” (Y) refers to the VOC transmission through the membrane comprising the cellulose-based layer within a specified time period. “VOC emission” Y0 refers to the VOC emission from the source during a certain amount of time period. “Reduced VOC transmission” and “VOC emission” can be measured as described in Example 3.Both VOC emissions and reduced VOC transmission can be measured according to the appropriate portion of the EN ISO 16000 series. VOC emissions and reduced VOC transmission can also be referred to as emission / transmission flux. “Reduced VOC transmission” can characterize the reduction in VOC emissions from the layered assembly relative to a separate substrate without a cellulose layer covering it. Thus, it can also characterize the level of VOC barrier provided by the cellulose-based layer in the assembly.

[0063] In a preferred embodiment of the first aspect of the invention, the VOC is any one of the following: formaldehyde, acetaldehyde, benzaldehyde, pentanal, 3-carene, nonanal, pinene, terpenes, hexanal, butyraldehyde, acetone, and / or dichloromethane. In a preferred embodiment, the VOC is formaldehyde. In one embodiment, the VOC may comprise a combination of any one of the following: formaldehyde, acetaldehyde, benzaldehyde, pentanal, 3-carene, nonanal, pinene, terpenes, hexanal, butyraldehyde, acetone, and / or dichloromethane.

[0064] In a preferred embodiment of the first aspect of the invention, the substrate comprises a natural fiber-based material and / or a wood-based material and / or a resin-impregnated material. Specification 7 / 14 pages 10 CN 121443448 A

[0065] The term "natural fiber-based material" describes a material that substantially comprises natural fibers. Such natural fibers may include, but are not limited to, wood fibers, hemp, straw, cellulose, wool, cotton, and flax. "Wood-based material" describes a material that substantially comprises natural or processed wood. The term "resin-impregnated material" describes a material that comprises resin impregnation (such as phenol-formaldehyde resin, urea-formaldehyde resin, melamine resin, or epoxy resin). Natural fiber materials, wood-based materials, and epoxy resin materials may be VOC emitters.

[0066] In a preferred embodiment of the first aspect of the invention, the substrate is a building structure. As used herein, the term "building structure" may refer to articles and / or materials commonly used in building and / or furniture applications. For example, in one embodiment, the building structure may be a panel, board, frame, roll, slat, or support. Examples of panels may include insulated panels or ceiling panels. Examples of boards may include gypsum board, solid wood boards, particleboard, perlite board, medium-density fiberboard (MDF), high-density fiberboard (HDF), oriented strand board (OSB), plywood, or wood-plastic composite (WPC) boards. In one embodiment, the layered assembly is a building structure.

[0067] In a preferred embodiment of a first aspect of the invention, the cellulose-based layer is in contact with the substrate at the covered surface. As used herein, the term "in contact with the substrate" means that the cellulose-based layer is in contact with the substrate, and no additional layer of another material is inserted between the substrate and the cellulose-based layer.

[0068] Method for Blocking VOCs

[0069] In a second aspect, the present invention relates to a method for blocking VOCs using a cellulose-based layer, wherein the cellulose-based layer has a thickness of at least 20 µm, preferably at least 30 µm, and more preferably at least 40 µm, and a density of at least 800 kg / m³, and wherein the cellulose-based layer is substantially impermeable to at least one VOC, preferably in a layered assembly.

[0070] The cellulose-based layer of the second aspect can be characterized according to any embodiment of the embodiments according to the first aspect. The cellulose-based layer of the second aspect of the invention can be prepared by the method for preparing a cellulose-based layer according to the third aspect of the invention, and its preparation can be further characterized in any of the manner specified herein.

[0071] The term “blocking VOCs” should be understood as in the first aspect. Blocking a home space (e.g., a room) and the occupants of the space from VOCs can take different forms. In one embodiment, the source of the VOC is clearly identifiable, and VOC emissions can be mitigated by covering the source with a cellulose-based layer impermeable to VOCs, preferably in a layered assembly according to the first aspect. In a different embodiment, the source of VOCs may be unidentifiable and / or remote, but a cellulose-based layer impermeable to VOCs can be used to isolate the home space from VOCs. Therefore, this disclosure also relates to the use of a cellulose-based layer impermeable to VOCs for blocking at least one VOC.

[0072] For example, in one embodiment, the VOC source is located in space A (e.g., a room) adjacent to space B (e.g., an adjacent room). Therefore, a cellulose-based layer impermeable to VOCs in the wall separating space A and space B can isolate space B from VOC emissions from the source in space A. In other words, the VOC concentration in space B can be reduced compared to the absence of a cellulose-based layer impermeable to VOCs because VOC transport through the cellulose layer is significantly reduced. In another exemplary embodiment, the VOC source may be completely unidentifiable, but a cellulose-based layer impermeable to VOCs can be used to reduce the VOC concentration in the space.

[0073] The relative reduction in VOC concentration due to the presence of a cellulose-based layer compared to the absence of a cellulose-based layer can be characterized as the “level of barrier”. For space A, a level of at least (LoI)% barrier to gas (g) provided by a cellulose-based layer that is impermeable to VOCs means that the concentration of gas (g) in space A is reduced by at least (LoI)% compared to the case where no cellulose-based layer is present.Specification 8 / 14 pages 11 CN 121443448 A

[0074] In the layered assembly of the first aspect, the barrier level is preferably characterized as a reduction in VOC transmission (X).

[0075] In one embodiment, the barrier level provided by the cellulose-based layer is at least 50%, preferably at least 55%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, more preferably at least 90%, more preferably at least 95%, and even more preferably at least 99%.

[0076] In a preferred embodiment, the VOC is formaldehyde, and the cellulose-based layer is used to block formaldehyde.

[0077] Method for preparing a layered assembly

[0078] In a third aspect, the present invention relates to a method for preparing a layered assembly according to the first aspect of the invention.

[0079] In a preferred embodiment of the third aspect of the invention, the method comprises configuring a cellulose-based layer on a substrate by any of the following: pressing, laminating, gluing, impregnating, binding, stapling, bonding, coating.

[0080] In one embodiment, the cellulose-based layer is pressed, laminated, glued, bound, stapled, or bonded to a substrate, thereby covering at least one surface of the substrate.

[0081] In a preferred embodiment of the third aspect of the invention, the method comprises preparing the cellulose-based layer by means of:

[0082] (i) providing a cellulose fiber layer precursor comprising natural cellulose fibers,

[0083] (ii) subjecting the cellulose fiber layer precursor to a cellulose dissolution step to produce a treated cellulose fiber layer comprising dissolved cellulose, and

[0084] (iii) subjecting the treated cellulose fiber layer to a reprecipitation step in which the dissolved cellulose is reprecipitated.

[0085] Several preferred embodiments of this embodiment will be discussed below, and wherein this embodiment is referred to as “the foregoing preferred embodiment of the third aspect”. Most preferably, the cellulose-based layer is prepared by means of steps (i)-(iii) before the cellulose-based layer is disposed on the substrate.

[0086] In step (i) of the aforementioned preferred embodiment of the third aspect, a cellulose fiber layer precursor comprising natural cellulose fibers is provided. For ease of reference, the terms "precursor material" and "cellulose fiber layer precursor" are used synonymously herein.The precursor material may contain at least 50% natural cellulose fibers, preferably at least 55% natural cellulose fibers, more preferably at least 60% natural cellulose fibers, more preferably at least 65% natural cellulose fibers, more preferably at least 70% natural cellulose fibers, more preferably at least 75% natural cellulose fibers, more preferably at least 80% natural cellulose fibers, more preferably at least 85% natural cellulose fibers, more preferably at least 90% natural cellulose fibers, and even more preferably at least 95% natural cellulose fibers. In one embodiment, the precursor material consists substantially or entirely of natural cellulose fibers. Preferably, the precursor material contains less than 1 wt% insoluble cellulose material. In one embodiment, the precursor material contains 80 wt% or more wood pulp.

[0087] In one embodiment, the precursor material may be any of the following: paperboard, absorbent paper, absorbent paper, filter paper, and / or cellulose paper towels.

[0088] In step (ii) of the aforementioned preferred embodiment of the third aspect, the cellulose fiber layer precursor undergoes a cellulose dissolution step to produce a treated cellulose fiber layer containing dissolved cellulose. In step (iii) of the aforementioned preferred embodiment of the third aspect, the treated cellulose fiber layer undergoes a reprecipitation step, wherein the dissolved cellulose is reprecipitated. As mentioned above, the preparation of the cellulose-based layer is most preferably carried out before it is disposed on a substrate. However, in an alternative embodiment, the cellulose fiber layer precursor may be disposed on the substrate, thereby covering at least one surface of the substrate when the substrate undergoes a cellulose dissolution step. If the preparation of the cellulose-based layer is carried out on the substrate, step (iii) of the aforementioned embodiment is still performed, such that the treated cellulose fiber layer containing dissolved cellulose undergoes a reprecipitation step, wherein the dissolved cellulose is reprecipitated.

[0089] In a preferred embodiment of the aforementioned preferred embodiment of the third aspect, the cellulose dissolution step comprises contacting the cellulose fiber layer precursor with a gelling agent, thereby subjecting the cellulose fiber layer precursor to a reaction with the gelling agent to dissolve the natural cellulose fibers, thereby producing the treated cellulose fiber layer, and wherein the reprecipitation step comprises subjecting the treated cellulose fiber layer to a reprecipitant.

[0090] In one embodiment, the cellulose dissolving step comprises at least partially impregnating a cellulose fiber layer precursor with a gelling agent, thereby subjecting the cellulose fiber layer precursor to a reaction with the gelling agent to dissolve the natural cellulose fibers, thereby producing a treated cellulose fiber layer.

[0091] The term "partial impregnation" herein means that only a portion of the natural cellulose fibers in the precursor material are in contact with the gelling agent, and that contact is achieved through impregnation.In one embodiment, 10%–99% by mass of the natural cellulose fibers in the precursor material are contacted with the gelling agent, more preferably 20%–99% by mass, more preferably 30%–99% by mass, more preferably 40%–99% by mass, more preferably 50%–99% by mass, more preferably 60%–99% by mass, more preferably 70%–99% by mass, more preferably 80%–99% by mass, and more preferably 90%–99% by mass. In another embodiment, substantially all of the natural cellulose fibers in the precursor material are contacted with the gelling agent.

[0092] In one embodiment, the gelling agent is provided in liquid form (e.g., in solution form). The gelling agent comprises at least one cellulose solvent selected from the group consisting of: inorganic acids comprising sulfuric acid and phosphoric acid, Lewis acids comprising ZnCl2 and Ca(SCN)2, inorganic bases comprising NaOH, organic bases comprising N-methylmorpholine N-oxide, and ionic liquids comprising tetraalkylammonium salts. Preferably, the gelling agent comprises sulfuric acid.

[0093] In one embodiment, the precursor material is porous and capable of absorbing the gelling agent, thereby causing impregnation when the precursor material comes into contact with the gelling agent. The degree of impregnation can be controlled by controlling the porosity of the precursor material, controlling the basis weight of the precursor material, controlling the pressure of contact with the gelling agent (e.g., by roller pressing), controlling the contact time between the precursor material and the gelling agent (e.g., by immersing the precursor material in the gelling agent for a predetermined time), adding an anti-reprecipitation agent, etc.

[0094] After at least partial impregnation with the gelling agent, the precursor material is subjected to a reaction with the gelling agent to dissolve the natural cellulose fibers, thereby obtaining a treated cellulose fiber layer. The reaction may be a chemical reaction. The extent to which the gelling agent dissolves the natural cellulose fibers depends on the degree of impregnation, as the gelling agent dissolves the fibers it directly contacts. Furthermore, the extent to which the reaction occurs depends on the nature and concentration of the gelling agent. For example, if 10 wt% of the precursor material is impregnated with the gelling agent, the gelling agent may dissolve 10 wt% or less of the natural cellulose fibers in the precursor material. In one embodiment, the gelling agent reacts with substantially all the natural cellulose fiber material in direct contact with it, thereby dissolving all the natural cellulose fiber material in direct contact with it. The reaction with the gelling agent and thus the dissolution of the natural cellulose fibers produce a treated cellulose fiber layer. Thus, the treated cellulose fiber layer comprises natural cellulose fibers and dissolved cellulose fibers, the dissolved cellulose fibers being a gel-like viscous material. Preferably, the treated cellulose fiber layer also comprises destructured cellulose fibers.

[0095] In a preferred embodiment of the foregoing preferred embodiment of the third aspect, the reprecipitation step comprises subjecting the treated cellulose-based substrate precursor material to a reprecipitant.In one embodiment, all dissolved cellulose fibers are subjected to a reprecipitant. In another embodiment, only a portion of the dissolved cellulose fibers are subjected to a reprecipitant. Preferably, at least the dissolved cellulose fibers are subjected to a reprecipitant.

[0096] The reprecipitant interrupts the reaction between the gelling agent and the natural cellulose fibers by eliminating the gelling agent. Thus, the gel-like viscous material containing the dissolved cellulose fibers precipitates into a solid material. This solid material can be a non-cellulose cellulose material and / or an insoluble cellulose material. The non-cellulose and / or insoluble cellulose material can be dry or wet. Preferably, the non-cellulose and / or insoluble cellulose material forms a continuous cellulose fiber matrix together with the destructured cellulose fibers.

[0097] In one embodiment, the reprecipitant is water. In such embodiments, "eliminating the gelling agent" means diluting and washing away the gelling agent. Other reprecipitants that eliminate the gelling agent (e.g., by neutralizing or deactivating it) can be used.

[0098] In a preferred embodiment of the foregoing preferred embodiments of the third aspect, the method may include an additional step (iv) in which the cellulose-based layer is further consolidated by a drying step. Optionally, step (iv) may include an additional separate washing step prior to the drying step. In one embodiment, step (iv) is performed on a substrate disposed on a substrate, thereby covering at least one surface of the substrate, thereby consolidating the cellulose-based layer covering at least one surface of the substrate.

[0099] In a preferred embodiment of the third aspect of the invention, the method includes preparing the cellulose-based layer by a wet web forming process, the wet web forming process including a refining step and / or calendering, preferably supercalendering. For example, in one embodiment, the cellulose-based layer may be a tracking paper or a supercalendered paper prepared by a supercalendering process.

[0100] Based on the foregoing discussion, the following embodiments, and not wishing to be bound by theory, the inventors provide a VOC-impermeable cellulose-based layer that may be disposed on a substrate in a layered assembly, or by providing a method for blocking VOCs using a VOC-impermeable cellulose-based layer. The combination of thickness, density, and VOC impermeability produces a material through which VOC molecules cannot permeate, thereby blocking the surrounding environment from VOC emissions. Therefore, the inventors believe that the problem of providing long-term VOC emission reduction from a completely biological source has been solved.

[0101] Examples

[0102] Example 1 - Determination of the amount of insoluble cellulose material

[0103] It is known that natural cellulose exhibits a cellulose I structure. During gelation and reprecipitation, for example in the parenchyma process, cellulose may exhibit a cellulose II structure with an antiparallel chain arrangement.Cellulose II is more stable than cellulose I and has lower solubility. Therefore, the level of parenchyma of the paper sample was indicated by dissolving the paper sample in a copper-ethylenediamine (CED) solution and measuring the amount of undissolved material.

[0104] 5 g of paper sample was torn into pieces of about 2 × 2 cm and then placed in an electric grinder for 60 seconds. The resulting pieces after grinding were 1–10 mm² in size. Next, the moisture content of the paper sample was measured by weight difference after drying in an oven at 105 °C for 30 minutes.

[0105] The test was performed in a temperature-controlled environment of 23 °C ± 1 °C.

[0106] 200 mg (± 2 mg) of sample was weighed and placed in a 50 mL Duran bottle. The weight was corrected by the moisture measurement from the sample to determine the dry sample weight for all further characterization. Three 10 mm glass beads were added to the Duran bottle and 20 mL of ultrapure water was added. Add 20 mL CED (1 M, in water) and purge the air on the top of the bottle with nitrogen before closing the cap. Then wrap the sealed bottle in aluminum foil and place it on a shaker at 200 rpm for 4 hours.

[0107] After 4 hours, the filtrate was recovered by vacuum filtration on two pre-weighed glass filters (MGC Ahlstrom and an MG 1502 pre-filter placed on top of the MGC). The filtrate on the filters was then dried at 130°C for 2 hours, and the filtrate weight was determined based on the difference from the initial filter weight. The undissolved content was then taken as the filtrate weight, which was expressed as a percentage of the initial dry weight of the sample.

[0108] Table 1 | Amount of insoluble cellulose material at different levels of parenchyma. Specification 11 / 14 pages 14 CN 121443448 A

[0109]

[0110] Figure 1 depicts a graphical representation of the data in Table 1.

[0111] Example 2 - Determination of Formaldehyde Transport Flux

[0112] Formaldehyde transport flux characterizes the formaldehyde barrier properties of a membrane with a certain surface area and thickness. In this paper, the formaldehyde transport flux is measured against a simulated emission source of a formaldehyde storage tank covered by a membrane. Formaldehyde molecules crossing the membrane are trapped in a water tank, where they can be detected by UV / Vis spectroscopy.

[0113] The experimental setup is described with reference to Figure 2. A formaldehyde storage tank (1) is covered by a membrane of sample (2) in a container (5). The container is sealed except for an air inlet (3) and an air outlet (4). The air inlet (3) is positioned above the sample (2), and the air outlet (4) is connected to a water trap.

[0114] The experiment was conducted at a temperature of 20°C. The formaldehyde concentration was set to 15 ppm or 1690 ppm in 15 mL of water. Water was placed in a partially sealed storage tank below the sample to be tested.An airflow of 10 cm³ / min was passed through the air inlet (3) and traveled across the top surface (2) of the sample. For a 70 gsm sample, the membrane of sample (2) had a surface area of ​​78.54 cm² and a thickness of 80 µm to 90 µm. The thickness may vary depending on other basis weights. In the embodiments described herein, the basis weight of the paper is typically between 60 gsm and 70 gsm; however, the method is also applicable to other basis weight ranges. Due to the difference in formaldehyde concentration between the tank and the clean air from the inlet, formaldehyde vapor from the tank (1) moved through the sample (2) by diffusion. These vapors were carried through the air outlet (4) into a water trap (6) containing 200 mL of water. The airflow was maintained for 6 hours, and the formaldehyde concentration was measured by UV / Vis spectroscopy after reaction with Nash's reagent. The absorbance at 412 nm was measured and compared with a calibration curve.

[0115] The formaldehyde concentration in the water trap was converted into formaldehyde transport flux, taking into account the surface area of ​​the membrane and the elapsed time.

[0116] Table 2 | Formaldehyde transport flux of different materials with different contents of insoluble cellulose material Specification 12 / 14 pages 15 CN 121443448 A

[0117]

[0118] The results in Table 2 are presented graphically in Figure 2 and clearly indicate that the VOC transport flux decreases sharply with the increase of the content of insoluble material, i.e. with the increase of the degree of parenchyma. The results in Table 2 also show that other types of paper with a dense structure (such as tracing paper or high-density paper) will act as a formaldehyde barrier compared with open paper such as absorbent paper.

[0119] Example 3 - Determination of VOC transport reduction

[0120] VOC transport reduction is characterized by the percentage reduction of formaldehyde emissions from the substrate due to the presence of a cellulose layer that is impermeable to VOCs.

[0121] Different papers were placed on top of wood-based panels (WBP) used as sources of VOCs and formaldehyde. Three parenchyma samples with different basis weights and levels of parenchyma were compared with kraft paper sheets. Two parchment samples B (medium parchmentation) with basis weights of 50 g / m² and 70 g / m², respectively, were used. A parchment sample D (very high parchmentation) with a basis weight of 70 g / m² was also used. For these tests, the paper and WBP samples were pre-cut to defined dimensions prior to testing. Each sheet of paper was placed on the top surface of the wood-based panel sample. The back and edges of the system (WBP + paper) were covered with a low-emission adhesive. The dimensions of the wood-based panel element and paper were 0.42 m × 0.17 m. To prepare the test sample, the adhesive covered 1 cm on each side of the vulcanized paper. Therefore, the emission surface area of ​​the test sample was approximately 0.06 m² (0.40 m × 0.15 m). The thickness of the wood panel was 18 mm.After preparation, the test samples were placed on a stainless steel support. The sample preparation (EN ISO 16000-11) and emission testing (EN ISO 16000-9) of all samples were the same. The analysis of formaldehyde and other aldehydes (carbonyl compounds) was performed according to ISO 16000-3. The remaining VOCs were analyzed according to ISO 16000-6. The VOC emissions (Y0) and the reduction in formaldehyde transport (Y) were determined according to EN ISO 16000-11, EN ISO 16000-9, ISO 16000-3 and ISO 16000-6, and a 14-day conditioning period was set for all samples. The reduction in formaldehyde transport (X) was then calculated according to Equation (1)

[0122] (1)

[0123] and the results are tabulated in Table 3 below.

[0124] The results in Table 3 show that at least 65% reduction in VOC transport can be easily achieved by providing a cellulose-based layer that is impermeable to VOCs on the substrate. Formaldehyde transmission reduction of over 98% can be easily achieved. Specification page 13 / 14 16 CN 121443448 A

[0125] Specification page 14 / 14 17 CN 121443448 A Figure 1 Figure 2 Specification drawing page 1 / 2 18 CN 121443448 A Figure 3 Specification drawing page 2 / 2 19 CN 121443448 A.

Claims

1. A layered assembly comprising a substrate and a cellulose-based layer configured on the substrate; wherein the cellulose-based layer has a thickness of at least 20 pm, preferably at least 30 pm, and more preferably at least 40 pm, and a density of at least 800 kg / m 3 3. wherein the cellulose-based layer covers at least one surface of the substrate; wherein the substrate contains at least one emitter of volatile organic compounds (VOCs); and wherein the cellulose-based layer is substantially impermeable to the VOCs.

2. The layered assembly according to claim 1, wherein the cellulose-based layer comprises a continuous cellulose fiber matrix comprising natural cellulose fibers and insoluble cellulose material.

3. The layered assembly according to any one of the preceding claims, wherein the content of the insoluble cellulose material in the continuous cellulose fiber matrix is from 10 wt% to 60 wt%, more preferably from 15 wt% to 55 wt%, when measured according to the description.

4. The layered assembly of any of the preceding claims, wherein the cellulose-based layer has a VOC transmission flux of at most 1.5E-04 mg / (cm2 2 · hr) when measured according to the specification.

5. The layered assembly according to any one of the preceding claims, wherein the layered assembly has a reduction of VOC transmission (X) of at least 50%, preferably at least 65%, when calculated according to formula (1): （1） wherein Y is the reduced VOC transmission, and Y0 is the VOC emission, wherein Y and Y0 are measured according to the description.

6. The layered assembly according to any one of the preceding claims, wherein the VOC is any one of formaldehyde, acetaldehyde, benzaldehyde, pentanal, 3-carene, nonanal, pinene, terpene, hexanal, butanal, acetone, and / or dichloromethane, preferably formaldehyde.

7. The layered assembly according to any one of the preceding claims, wherein the substrate comprises natural fiber-based material and / or wood-based material and / or resin impregnated material.

8. The layered assembly according to any one of the preceding claims, wherein the substrate is a building structure; such as a laminated paper structure, a barrier panel, a ceiling panel, a fiber-based barrier material, a plasterboard, a solid wood panel, a particle board, a waferboard, a medium density fiberboard (MDF), a high density fiberboard (HDF), an oriented strand board (OSB), a plywood, or a wood plastic composite (WPC) panel.

9. The layered assembly according to any one of the preceding claims, wherein the cellulose-based layer is in contact with the substrate at the covered surface.

10. A method of blocking VOCs using a cellulose-based layer, wherein the cellulose-based layer has a thickness of at least 20 pm, preferably at least 30 pm, and more preferably at least 40 pm, and a density of at least 800 kg / m3, and wherein the cellulose-based layer is substantially impermeable to at least one VOC, preferably in a layered assembly. 3 of at least 800 kg / m3, and wherein the cellulose-based layer is substantially impermeable to at least one VOC, preferably in a layered assembly.

11. A method for preparing a layered assembly according to any one of claims 1 to 9, wherein the method comprises configuring the cellulose-based layer on the substrate by any one of pressing, laminating, gluing, impregnating, stapling, nailing, bonding, coating.

12. The method according to claim 11, wherein the method comprises preparing the cellulose-based layer by a method comprising: (i) a step of providing a cellulose fiber layer precursor comprising natural cellulose fibers, (ii) subjecting the cellulose fiber layer precursor to a cellulose dissolution step to yield a treated cellulose fiber layer comprising dissolved cellulose, and (iii) subjecting the treated cellulose fiber layer to a re-precipitation step in which the dissolved cellulose is re-precipitated.

13. The method according to claim 12, wherein the cellulose dissolving step comprises contacting the cellulose fiber layer precursor with a gelling agent, thereby subjecting the cellulose fiber layer precursor to a reaction with the gelling agent to dissolve natural cellulose fibers, thereby producing a treated cellulose fiber layer, and wherein the re-precipitation step comprises subjecting the treated cellulose fiber layer to a re-precipitation agent.

14. The method according to claim 11, wherein the method comprises producing the cellulose-based layer by a wet-laid process, the wet-laid process comprising a refining step and / or a calendering, preferably a super-calendering.

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