Flexible soft wipes containing individualized bast fibers

Abstract

The present invention relates to a nonwoven substrate comprising individualized flax fibers containing specific cellulose, hemicellulose, and lignin contents.

Description

[Technical Field]

[0001] The subject of the present invention is a nonwoven substrate comprising wood fibers and individualized bast fibers. [Background technology]

[0002]

[0002] Disposable wipes are traditionally made of non-biodegradable synthetic resin fibers, such as polyester fibers and thermoplastic fibers. Conventional disposable wipes are rarely recycled by users. Therefore, conventional disposable wipes have a significant impact on the environment due to the long synthetic resin fibers they contain.

[0003]

[0003] To limit the environmental impact of disposable wipes, it has been proposed to replace synthetic or artificial fibers with bast fibers. However, these wipes are rough and not flexible enough to easily conform to the face of the cosmetic wipe user. Therefore, the sensation the wipes provide to the user is unsatisfactory. Furthermore, these wipes are difficult to manufacture because bast fibers are inherently stiff and have little flexibility. Summary of the Invention [Problem to be solved by the invention]

[0004]

[0004] Therefore, there is a need for wipes that are soft, pleasant to the touch, and easy to manufacture.

[0005] It is therefore to the inventors' credit that they have discovered that this need can be met by individualized bast fibers that are easy to manufacture and characterized by specific cellulose, lignin, and hemicellulose contents. [Means for solving the problem]

[0005]

[0006] - 40% to 95% by weight of wood fibres relative to the total weight of fibres in the substrate, and - 5% to 60% by weight of individualized bast fibers relative to the total weight of the fibers in the substrate wherein the individualized bast fibers have a cellulose content of 75% or more, a hemicellulose content of 10% or less, and a lignin content of 7% or less, based on the dry weight of the individualized bast fibers.

[0006]

[0007] Advantageously, the nonwoven substrate of the present invention is pleasant to the touch, soft, has a natural color, and possesses mechanical properties, particularly dry and wet tensile strength, that are on the same order of magnitude as nonwoven materials that do not contain individualized bast fibers.

[0007]

[0008] According to another aspect, there is provided a method of making a nonwoven substrate of the present invention, comprising the steps of: a) treating bast fibers under pressure in a solvent to obtain individualized bast fibers; b) mixing the individualized bast fibers with wood fibers to obtain a fiber mixture; and c) producing a nonwoven substrate from the fiber mixture by a wet-laid process, by a dry-laid process or by an air-laid process, in particular by a wet-laid process; A method is proposed, including:

[0008]

[0009] Advantageously, the processing step a) of the method of the present invention allows for the easy production of individualized bast fibers with specific cellulose, hemicellulose, and lignin contents, and therefore allows for the easy production of flexible nonwoven substrates that are pleasant to the touch and have mechanical properties comparable to those of nonwoven substrates containing chemically untreated bast fibers. [Brief explanation of the drawings]

[0009] [Figure 1]

[0010] FIG. 1 shows a microscopic image of flax fibers that have undergone treatment under pressure according to the present invention. [Figure 2]

[0011] FIG. 1 shows a microscopic image of flax fibers that have undergone treatment under pressure according to the present invention. [Figure 3]

[0012] FIG. 1 shows a microscopic image of flax fibers that have undergone treatment under pressure according to the present invention. [Figure 4]

[0013] FIG. 1 shows a microscopic image of flax fibers that have undergone treatment under pressure according to the present invention. [Figure 5]

[0014] FIG. 1 shows a microscopic image of flax fibers that have undergone treatment under pressure according to the present invention. [Figure 6]

[0015] FIG. 1 shows a microscopic image of flax fibers that have undergone comparative treatments. [Figure 7]

[0016] 1 is a graph showing the dry tensile strength of control substrates, comparative substrates, and substrates of the present invention. [Figure 8]

[0017] 1 is a graph showing strain at break for control substrates, comparative substrates, and substrates of the present invention. [Figure 9]

[0018] FIG. 1 shows an optical microscope image of a substrate according to the invention (optical zoom ×200, two circles added). [Figure 10]

[0019] FIG. 1 shows an optical microscope image of a comparative substrate (optical zoom ×200, three circles added). DETAILED DESCRIPTION OF THE INVENTION

[0010]

[0020] According to one aspect, the present invention provides a method for producing a method for manufacturing a semiconductor device comprising: - 40% to 95% by weight of wood fibres relative to the total weight of fibres in the substrate, and - 5% to 60% by weight of individualized bast fibers relative to the total weight of the fibers in the substrate wherein the individualized bast fibers have a cellulose content of 80% or more, a hemicellulose content of 10% or less, and a lignin content of 9.5% or less, based on the dry weight of the individualized bast fibers.

[0011]

[0021] In this application, the term "nonwoven substrate" means a manufactured sheet consisting of a web or layer of unidirectional or randomly oriented fibers bound together by friction and / or cohesion and / or adhesion, with the exception of paper and products obtained by weaving, knitting, tufting, or sewing, which incorporate binding threads or filaments, or which are felted by wet felting, whether or not needlepunched.

[0012]

[0022] In this application, the term "bast fibers" means plant fibers contained in the secondary phloem of plants.

[0023] As bast fibers, mention may be made of hemp fibers, Indian hemp fibers, jute fibers, kenaf fibers, kudzu fibers, coin vine fibers, flax fibers, okra fibers, nettle fibers, papyrus fibers, ramie fibers, sisal fibers, esparto fibers, or mixtures thereof, in particular hemp fibers, flax fibers, or mixtures thereof, especially flax fibers.

[0013]

[0024] Typically, bast fibers consist of cellulose, hemicellulose, lignin, and other compounds such as pectin, proteins, waxes, and inorganic compounds. In the present application, the term "individualized bast fibers" refers to basic bast fibers having a cellulose, hemicellulose, and lignin content of 98.5% or more, particularly 98.75%, and especially 99%. Individualized bast fibers are obtained during the simple step of treating the bast fibers in a solvent under pressure.

[0014]

[0025] Without wishing to be bound by any theory, the inventors are of the opinion that simple treatment under pressure in a solvent allows the pectin cement to dissolve, resulting in the individualized bast fibers of the present invention having specific cellulose, lignin, and hemicellulose contents.

[0015]

[0026] Treatment under pressure in a solvent also makes the individualized bast fibers of the present invention very flexible. Advantageously, this high flexibility of the individualized bast fibers provides pliability and mechanical properties to the nonwoven substrate of the present invention, as the individualized bast fibers are well collected.

[0016]

[0027] Furthermore, these individualized bast fibers intertwine with one another better than non-individualized bast fibers, and as a result, the nonwoven substrate of the present invention is more pleasant to the touch, particularly softer and less rough, than substrates comprising non-individualized bast fibers.

[0017]

[0028] The individualized bast fibers of the nonwoven substrate of the present invention are characterized by a specific cellulose, lignin, and hemicellulose content. In particular, the individualized bast fibers have, based on the dry weight of the individualized bast fibers: Cellulose content between 80% and 98%, especially between 89% and 97% Hemicellulose content between 0.5% and 10%, especially between 1% and 5.5%, and Lignin content between 1% and 9.5%, especially between 1.5% and 5% It can have:

[0018]

[0029] The content of cellulose, lignin, and hemicellulose may depend on the nature of the bast fibers.

[0030] For example, individualized flax fiber may contain, by dry weight of the individualized flax fiber: Cellulose content of 80% or more, especially between 85% and 98%, especially between 95% and 97%; a hemicellulose content of 9% or less, in particular between 0.75% and 7.5%, especially between 1% and 3%, and Lignin content less than 5%, especially between 1% and 4%, and especially between 1.5% and 2% It can have:

[0019]

[0031] The individualized hemp fiber may have, for example, a dry weight of the individualized hemp fiber of: Cellulose content of 80% or more, especially between 80% and 98%, especially between 89% and 93%; a hemicellulose content of 10% or less, in particular between 0.5% and 10%, especially between 2% and 5.5%, and Lignin content less than 10%, especially between 2.5% and 9%, and especially between 3% and 5% It can have:

[0020]

[0032] The SCAN-CM71 (2009) method will be used to measure the cellulose and hemicellulose content in the individualized fibers relative to the dry weight of the individualized bast fibers.

[0021]

[0033] In the present invention, the lignin content in the individualized fibers relative to the dry weight of the individualized bast fibers corresponds to the sum of the insoluble lignin content and the soluble lignin content, where the insoluble lignin content is measured in accordance with the TAPPI 222 (2006) method, and the soluble lignin content is measured by a conventional method using UV spectrophotometry.

[0022]

[0034] The individualized bast fibers may have a length between 1 mm and 150 mm, in particular between 1.5 mm and 100 mm, especially between 2 mm and 50 mm.

[0035] According to one embodiment, the individualized bast fibers may have a length between 4 mm and 20 mm, in particular between 6 mm and 15 mm, more particularly between 8 mm and 14 mm, and even more particularly between 10 mm and 12 mm.

[0023]

[0036] According to an alternative embodiment, the individualized bast fibers may have a length between 20 mm and 150 mm, in particular between 30 mm and 100 mm, especially between 35 mm and 50 mm.

[0024]

[0037] According to another alternative embodiment, the individualized bast fibers may have a length between 1 mm and 10 mm, in particular between 1.5 mm and 8 mm, especially between 2 mm and 5 mm.

[0038] The bast fibers can be cut before treatment under pressure to have lengths falling within the ranges mentioned above. Conventional cutting techniques that can be used are guillotine cutting of the bast fibers or milling of the bast fibers with or without an air cyclone or sieve system to remove excessively short and excessively long fibers.

[0025]

[0039] Bast fibers, particularly flax or hemp fibers, may be "cottonized" bast fibers, which are bast fibers that have been modified to have lengths in the above ranges and attenuated to pass through a cotton spinning machine.

[0026]

[0040] The amount of individualized bast fibers in the nonwoven substrate of the present invention may be from 10% to 50% by weight, especially from 15% to 30% by weight, based on the total weight of fibers in the substrate.

[0041] The individualized bast fibers have certain characteristics, and the subject of the present invention is the individualized bast fibers described above. The individualized bast fibers of the present invention have a cellulose content of 80% or more, a hemicellulose content of 10% or less, and a lignin content of 9.5% or less, based on their dry weight.

[0027]

[0042] Typically, the wood fibers are derived from hardwood pulp, softwood pulp, or mixtures thereof, especially softwood pulp.

[0043] The amount of wood fibres in the nonwoven substrate of the invention may in particular be from 60% to 90% by weight, more particularly from 80% to 85% by weight, based on the total weight of fibres in the substrate.

[0028]

[0044] The nonwoven substrate of the present invention may also comprise additional fibers, in particular lyocell fibers, selected from lyocell fibers (cellulose fibers that have been ground and dissolved in N-methylmorpholine N-oxide monohydrate to obtain fibers with a calibrated linear density and length and various cross-section shapes (round, oval, cross, circular, layered cross-section) that can be selected according to requirements by a person skilled in the art), viscose fibers (obtained by dissolving cellulose through modification of the hydroxyl groups with carbon disulfide (CS2) and then precipitation in the presence of sulfuric acid (H2SO4) to obtain fibers with a calibrated linear density and length and various cross-section shapes (round, oval, cross, circular, layered cross-section) that can be selected according to requirements by a person skilled in the art), cellulose acetate fibers, biodegradable polymer fibers, and mixtures thereof.

[0029]

[0045] Advantageously, lyocell fibers may increase the softness and dry strength of the vegetable paper according to the present invention.

[0046] In this application, "biodegradable polymer fibers" refers to polymer fibers that are rapidly decomposed by natural or induced bacterial action and eliminated from the environment by converting them into simple molecules that can be used by plants. Examples of biodegradable polymer fibers are polylactic acid (PLA) fibers, polyhydroxyalkanoic acid (PHA) fibers, and mixtures thereof. Polyhydroxyalkanoic acid (PHA) may include poly(β-hydroxybutyric acid) (PHB).

[0030]

[0047] For example, the amount of additional fibers in the nonwoven substrate of the present invention may be up to 15% by weight, particularly 1% to 10% by weight, and especially 4% to 6% by weight, based on the total weight of fibers in the substrate.

[0031]

[0048] Typically, the additional fibres may have a length of 1 mm or more, in particular 4 mm to 20 mm, especially 9 mm to 11 mm.

[0049] The additional fibres may have a fineness of 0.5 dTex to 2.5 dTex, in particular 1 dTex to 2 dTex, especially 1.25 dTex to 1.75 dTex.

[0032]

[0050] The additional fibres may also have a fineness of 2.5 dTex to 30 dTex, in particular 2.75 dTex to 10 dTex, especially 3 dTex to 3.5 dTex.

[0051] According to one particular embodiment, the nonwoven substrate comprises: 75% to 85% by weight of wood fiber, based on the total weight of the fibers in the substrate; and 15% to 20% by weight of individualized bast fibers, in particular individualized flax fibers, based on the total weight of the fibers of the substrate; 4% to 6% by weight of additional fibers, especially lyocell fibers, based on the total weight of fibers in the substrate Including, The individualized bast fibers have a cellulose content of 88% to 99%, a hemicellulose content of 0.5% to 6%, particularly 1% to 4%, and a lignin content of 1% to 4%, particularly 1.5% to 3%, based on the dry weight of the individualized bast fibers.

[0033]

[0052] The nonwoven substrate of the present invention may also include additives commonly used for paper production to develop or impart novel properties to the substrate, such as chemical, optical, sensory, or mechanical properties, such as dry strength, wet strength, and / or folding endurance.

[0034]

[0053] Additives may include wet strength agents, dry strength agents, softeners, active ingredients, lotion compositions, wetting agents, latexes, or mixtures thereof, particularly wet strength agents, dry strength agents, active ingredients, lotion compositions, or mixtures thereof, especially wet strength agents and active ingredients.

[0035]

[0054] For example, the amount of additive is less than 3% by weight of the substrate solids, particularly 0.5% to 2% by weight of the substrate solids, and especially 1.3% to 1.7% by weight of the substrate solids.

[0055] The wet strength agent can reduce the likelihood of the nonwoven substrate of the present invention being degraded when the nonwoven substrate of the present invention is brought into contact with a liquid such as water. For example, the wet strength agent can be selected from polyamides, such as epichlorohydrin resins, polyamine-epichlorohydrin resins, polyamide-epichlorohydrin resins, poly(aminoamide)-epichlorohydrin resins, urea-formaldehyde resins, melamine-formaldehyde resins, alkyl-ketene dimers, alkylsuccinic anhydrides, polyvinylamines, oxidized polysaccharides, and mixtures thereof.

[0036]

[0056] The dry strength agent allows the nonwoven substrate of the present invention to have increased strength when subjected to substantial mechanical loads. The dry strength agent may be selected from starch and modified rubbers, cellulose polymers, synthetic polymers such as carboxymethyl cellulose, polyacrylamide, and mixtures thereof.

[0037]

[0057] The softener can improve the softness of the nonwoven substrate of the present invention. Typically, the softener is a fatty acid, a siloxane compound, a silicone compound, an aminosilicone compound, an aloe vera extract, a sweet almond extract, a chamomile extract, a quaternary ammonium compound, and mixtures thereof.

[0038]

[0058] The active ingredient may be selected from sebum regulating agents, mattifying agents, astringents, acidifying agents, healing agents, exfoliants or keratin regulating agents, occlusive agents, protective agents, emollients, nourishing agents, moisturizers, anti-aging agents, soothing agents, decongestants or venotonics, UV blocking agents, moisture absorbing agents, gelling agents, free radical scavengers, cell regenerating or cell stimulating agents, stabilizers, firming agents, anti-glycation agents, whitening agents, or mixtures thereof.

[0039]

[0059] Biocidal compounds may include antimicrobial agents, antibacterial agents, disinfectants, or mixtures thereof.

[0060] Examples of decongestants are menthol extract and / or eucalyptus extract.

[0040]

[0061] Vitamin E is an example of a moisturizer.

[0062] The humectant may be a sugar alcohol such as glycerol or sorbitol, a glycol, for example propylene glycol, butylene glycol, pentylene glycol, or dipropylene glycol, or polyethylene glycol, or mixtures thereof, especially glycerol.

[0041]

[0063] Advantageously, the humectants provide conformability, softness, texture, and resistance to marking to the nonwoven substrate of the present invention, and further, the nonwoven substrate of the present invention advantageously has the ability to satisfactorily absorb, retain, and release cosmetic lotions.

[0042]

[0064] Typically, the nonwoven substrate of the present invention has a basis weight of 15 g / m 2 from 90 g / m 2 , especially 35g / m 2 from 75 g / m 2 It has.

[0065] Advantageously, basis weights in these value ranges provide the nonwoven substrates of the present invention with conformability (the ability of the nonwoven substrates of the present invention to conform to the shape of the user's face) and satisfactory absorption and release capacities for cosmetic applications.

[0043]

[0066] The nonwoven substrate of the present invention may also undergo additional treatments known to the paper industry, such as hydrocrossing treatment.

[0067] Thus, one embodiment of the present invention is the nonwoven substrate described above, in which the fibers are entangled.

[0044]

[0068] The bulk of entangled nonwoven substrates is greater than the bulk of nonwoven substrates that are not entangled, and as a result, the entangled nonwoven substrates are advantageously more pleasant to the touch, particularly softer, less coarse, and have a higher absorbent capacity.

[0045]

[0069] The properties of the nonwoven substrate of the present invention allow it to be used as a cosmetic wipe, a sanitary wipe, a facial mask, or a household wipe.

[0070] According to one aspect, the present invention relates to wipes, particularly cosmetic, sanitary or household wipes, comprising the nonwoven substrate of the present invention.

[0046]

[0071] The nonwoven substrate of the present invention is made according to a method comprising the following steps. a) treating bast fibers under pressure in a solvent to obtain individualized bast fibers; b) mixing the individualized bast fibers with wood fibers to obtain a fiber mixture; and c) Producing a nonwoven substrate from the fiber mixture by a wet-laid process, by a dry-laid process or by an air-laid process, in particular by a wet-laid process.

[0047]

[0072] In process step a) of the method of the present invention, the bast fibers are mixed with a solvent, for example, in a reactor operating under pressure, and then this mixture is placed under pressure to obtain singulated bast fibers, which are then separated from the solvent, for example, by passing through a screw press or a centrifuge, to obtain singulated bast fibers on the one hand and the solvent on the other hand.

[0048]

[0073] The treatment step a) is carried out under pressure, i.e. at a pressure above atmospheric pressure, in particular between 500 kPa (5 bar) and 1000 kPa (10 bar), in particular between 700 kPa (7 bar) and 850 kPa (8.5 bar). Advantageously, the pressure makes it possible to promote individualization of the fibers.

[0049]

[0074] According to one embodiment, the temperature of the solvent during step a) may be above ambient temperature, for example between 50°C and 250°C, in particular between 100°C and 200°C, and especially between 160°C and 170°C.

[0050]

[0075] The duration of the treatment step a) will depend on the bast fibers. Typically, this duration may be greater than or equal to 5 minutes, in particular greater than or equal to 60 minutes, especially between 120 and 300 minutes.

[0051]

[0076] According to one embodiment, the solvent is an aqueous solvent, in particular the solvent is water.

[0077] During step a), the weight of the solvent is typically greater than the dry weight of the bast fibers, and thus the ratio of the weight of the solvent to the dry weight of the bast fibers may be between 1.1 and 20, in particular between 2 and 10, and especially between 2.5 and 3.5.

[0052]

[0078] The treatment step a) of the method of the present invention may be an alkaline or acid treatment, in particular an alkaline treatment.

[0079] The solvent may contain additives such as acids or bases.

[0053]

[0080] The acid may be a bisulfite such as sodium or calcium bisulfite.

[0081] The base may be calcium sulfite, calcium carbonate, sodium hydroxide, sodium sulfite, sodium carbonate, a mixture of sodium hydroxide and anthraquinone, or mixtures thereof, in particular sodium hydroxide, or a mixture of sodium sulfite and sodium carbonate.

[0054]

[0082] The weight concentration of the additive in the solvent depends on the additive. For example, the concentration of a mixture of sodium sulfite and sodium carbonate may be 1% to 20% sodium sulfite and 0.25% to 10% sodium carbonate, particularly 2% to 8% sodium sulfite and 0.8% to 3% sodium carbonate. The weight concentration of sodium hydroxide in the solvent may be, for example, between 0.5% and 20%, particularly between 1% and 15%, more particularly between 2% and 7%, and even more particularly between 5.5% and 6.5%.

[0055]

[0083] According to a first particular variant, treatment step a) is carried out at a solvent temperature between 165°C and 170°C, at a pressure between 800 kPa (8 bar) and 850 kPa (8.5 bar), for a time between 110 and 120 minutes, the solvent being water containing a mixture of sodium sulfite and sodium carbonate, the sodium sulfite concentration in the solvent being between 2% and 8% and the sodium carbonate concentration in the solvent being between 0.8% and 3%.

[0056]

[0084] According to a second particular variant, treatment step a) is carried out at a solvent temperature between 160°C and 165°C, at a pressure between 650 kPa (6.5 bar) and 750 kPa (7.5 bar), for a time between 170 and 190 minutes, the solvent being water containing sodium hydroxide, the sodium hydroxide concentration in the water being between 1% and 10%, in particular between 5.5% and 6.5%.

[0057]

[0085] The bast fibers may undergo a pretreatment step, such as soaking, before treatment step a) of the method of the present invention.

[0086] Before the treatment step a), the bast fibers may undergo a cutting step a1) to obtain chopped bast fibers, the length of the chopped bast fibers being between 1 mm and 150 mm, in particular between 1.5 mm and 100 mm, more particularly between 2 mm and 50 mm.

[0058]

[0087] According to one embodiment, the chopped bast fibers may have a length between 4 mm and 20 mm, in particular between 6 mm and 15 mm, especially between 10 mm and 12 mm.

[0088] According to an alternative embodiment, the chopped bast fibers may have a length between 20 mm and 150 mm, in particular between 30 mm and 100 mm, especially between 35 mm and 50 mm.

[0059]

[0089] According to an alternative embodiment, the chopped bast fibers may have a length between 1 mm and 10 mm, in particular between 1.5 mm and 8 mm, especially between 2 mm and 5 mm.

[0090] The cutting step a1) can be carried out by conventional techniques, for example by guillotine cutting or by comminution of the bast fibres with or without the use of an air cyclone or sieve system to remove the excessively short and excessively long fibres.

[0060]

[0091] The bast fibers, in particular flax or hemp fibers, used in the mixing step b) of the method of the present invention may also be "cottonized" bast fibers, which are bast fibers modified to have lengths in the above ranges and attenuated to pass through a cotton spinning machine.

[0061]

[0092] The singulated bast fibers can then undergo a washing step, for example in water, optionally followed by a drying step.

[0093] Additional fibers can be added to the individualized bast fibers and wood fibers, for example, during the mixing step b) to obtain a fiber mixture.

[0062]

[0094] Step c) can be carried out using conventional wet-laid processes for producing paper, especially wet-laid processes that require a tilting bed. Those skilled in the art will know how to adjust the parameters of the wet-laid process to produce a nonwoven substrate.

[0063]

[0095] The wet-laid method is particularly suitable for individualized bast fibers having a length between 4 mm and 20 mm, in particular between 6 mm and 15 mm, especially between 10 mm and 12 mm.

[0064]

[0096] The dry-laid method is particularly suitable for individualized bast fibers having a length between 20 mm and 150 mm, in particular between 30 mm and 100 mm, especially between 35 mm and 50 mm.

[0065]

[0097] For the airlaid method, it is particularly suitable for individualized bast fibers having a length between 1 mm and 10 mm, in particular between 1.5 mm and 8 mm, especially between 2 mm and 5 mm.

[0066]

[0098] Step c) can alternatively be carried out by dry-laid or air-laid processes for producing paper. Dry-laid or air-laid processes typically allow for the formation of a web, which can then undergo a consolidation step to form the nonwoven substrate of the present invention. Advantageously, the consolidation step improves the cohesion of the fibers and thus makes it possible to consolidate the structure of the nonwoven substrate of the present invention. Consolidation techniques may include mechanical consolidation, thermal consolidation, chemical consolidation, and mixtures thereof, in particular mechanical consolidation.

[0067]

[0099] The individualized bast fibers undergoing step c) for drylaid or airlaid production of paper can undergo a drying step b1) before step b).

[0100] Drying step b1) can be carried out at temperatures between 50°C and 120°C, in particular between 60°C and 90°C. These temperature ranges advantageously allow the duration of this drying step b1) to be minimized, while at the same time minimizing fiber degradation and thus optimizing the inventive method. Advantageously, this drying step b1) makes it possible to limit or even avoid agglomerations of the dried individualized bast fibers. Thus, the inventive method does not require the lengthy and expensive step of fiber agglomeration. Drying step b1) can be carried out, for example, in a tunnel, in a rotary air dryer, or by winding the fibers and through-air drying. Advantageously, in contrast to conventional drying using drying rolls, these drying techniques also make it possible to minimize or even limit agglomerations of the dried individualized bast fibers.

[0068]

[0101] The nonwoven substrate produced during step c) may undergo an entanglement process to prepare a nonwoven substrate with entangled fibers.

[0102] Thus, one aspect of the present invention is a method for preparing a fiber-entangled nonwoven substrate, the method comprising a step in which the nonwoven substrate produced during step c) of the method according to the invention undergoes an entanglement step d), such as mechanical consolidation, thermal consolidation, chemical consolidation or a mixture thereof, in particular mechanical consolidation, chemical consolidation or a mixture thereof, especially mechanical consolidation followed finally by chemical consolidation.

[0069]

[0103] Heat consolidation uses the thermoplastic properties of synthetic fibers to entangle the fibers of the nonwoven substrate.

[0104] Chemical consolidation consists in entangling the fibers of the nonwoven substrate by coating them with a binder in solution, such as cationic starch or a latex of styrene butadiene rubber.

[0070]

[0105] Mechanical consolidation consists of the physical entanglement of the fibers of the nonwoven substrate. Examples of mechanical consolidation are needle punching and hydroentanglement, especially hydroentanglement.

[0106] According to a particular embodiment, the entanglement treatment of step d) is a hydroentanglement treatment.

[0071]

[0107] Typically, hydroentangling uses water jets under pressure, which can be between 2000 kPa (20 bar) and 80,000 kPa (800 bar), to entangle the fibers of a nonwoven substrate. The nonwoven substrate is circulated over one or more tables or conveyed from roller to roller, and injectors are installed to inject pressurized water onto its surface. The water jets are created when pressurized water passes through perforated strips or nozzles, e.g., 80 μm to 150 μm in diameter, arranged in one or more rows, typically 3 mm to 5 mm apart, with 1 to 3 holes per millimeter. Typically, the water pressure can increase from the first to the last injector. These very fine water jets penetrate the nonwoven substrate and bounce off the tables or rollers or from an intermediate belt, entangling the fibers with each other. The two sides of the nonwoven substrate can undergo this hydroentangling process one or more times. To avoid waterlogging the nonwoven substrate, a suction box may be installed under the table(s) or inside the roller. The residual water sucked up by the suction box is then recirculated, cleaned of any impurities, and can be reused. The thus consolidated nonwoven substrate can then be dried by drying rolls, tunnels, or through-air drying rolls.

[0072]

[0108] Advantageously, the sensory properties of the nonwoven substrate of the present invention that have undergone hydroentanglement are improved, particularly softness and absorbency. Furthermore, the nonwoven substrate of the present invention that has undergone hydroentanglement can form uniform pleats when suspended, and the nonwoven substrate has greater tensile strength and is easily molded. Due to the improvements in sensory properties, particularly softness and conformability, the nonwoven substrate of the present invention that have undergone hydroentanglement can also be advantageously used as a substrate for the previously described cosmetic and hygiene products.

[0073]

[0109] Typically, additives may be added to the fiber mixture before, during, or after step c), or after step d). For example, additives may be added after step c) or after step d) using a size press, coating, spraying, etc. In particular, wet strength agents may be added to the fiber mixture before it undergoes step c) to improve the interaction between the wet strength agents and the wood fibers.

[0074]

[0110] Typically, after step c) or after step d), the nonwoven substrate of the present invention can be dried by a drying device such as a drying roll, a through-air roll, or a tunnel.

[0075]

[0111] The nonwoven substrate of the present invention may also undergo additional processes known to the paper industry. Typically, one of these processes involves the use of multiple headboxes to produce a multi-layer nonwoven substrate.

[0076]

[0112] The nonwoven substrate of the present invention may also be subjected to a cutting step e) to produce the wipes described above.

[0113] Thus, one aspect of the present invention is a method for preparing wipes, comprising step e) cutting a nonwoven substrate prepared by a method according to the present invention or a nonwoven substrate having entangled fibers prepared by a method according to the present invention.

[0077]

[0114] This cutting step e) is a conventional step, and those skilled in the art will know how to adjust the cutting step to obtain the desired wipe. [Example]

[0078] Example 1

[0115] Bast fibers individualized by the method according to the invention

[0079] Example 1.1

[0116] The treatment of the flax fibres is carried out at a pressure of 700 kPa (7 bar) and a temperature of 164°C, the solvent being pure water.

[0080]

[0117] The individualized flax fibers are obtained under pressure according to the following process: The flax fibers are cut so that they have a length of 8 mm. The cut flax fibers and the solvent, i.e., water, are mixed in a reactor operating under pressure and temperature such that the ratio of the dry weight of the flax fibers to the volume of the water is 0.33. The solvent / fiber mixture is heated to 164°C over 26 minutes, and the pressure in the reactor is increased to 700 kPa (7 bar). The temperature of 164°C and the pressure of 700 kPa (7 bar) are maintained for 120 minutes. After this treatment, the flax fibers are separated from the solvent, washed with water for 60 minutes, centrifuged, and finally dried at 105°C for 16 hours.

[0081] Example 1.2

[0118] The treatment of the flax fibres is carried out at a pressure of 700 kPa (7 bar) and a temperature of 164°C, the solvent comprising water and 6% sodium hydroxide.

[0082]

[0119] The treatment under pressure that makes it possible to obtain individualized flax fibers is similar to that described in Example 1.1, with the difference that the solvent contains water and 6% sodium hydroxide and the solvent / fiber mixture is heated to 164°C for 15 minutes.

[0083] Example 1.3

[0120] The treatment of the flax fibres is carried out at a pressure of 700 kPa (7 bar) and a temperature of 164°C, the solvent comprising water and 2% sodium hydroxide.

[0084]

[0121] The treatment under pressure that makes it possible to obtain individualized flax fibers is similar to that described in Example 1.1, with the difference that the solvent contains water and 2% sodium hydroxide and the solvent / fiber mixture is heated to 164°C for 22 minutes.

[0085] Example 1.4

[0122] The treatment of the flax fibres was carried out at a pressure of 820 kPa (8.2 bar) and a temperature of 170°C, and the solvent comprised water, 7.5% sodium sulphite and 2.5% sodium carbonate.

[0086]

[0123] The individualized flax fibers are obtained according to the following process under pressure. The flax fibers are cut so that the length of the flax fibers in the bundles is 8 mm. The cut flax fibers and the solvent, i.e., water, 7.5% sodium sulfite, and 2.5% sodium carbonate, are mixed in a reactor operating under pressure and temperature such that the ratio of the dry weight of the flax fibers to the volume of the water is 0.33. The solvent / fiber mixture is heated to 170°C over 7 minutes, and the pressure in the reactor is increased to 820 kPa (8.2 bar). The temperature of 170°C and the pressure of 830 kPa (8.3 bar) are maintained for 180 minutes. After this treatment, the flax fibers are separated from the solvent, washed with water for 60 minutes, centrifuged, and finally dried at 105°C for 16 hours.

[0087]

[0124] The cellulose, hemicellulose, and lignin contents of flax fibers that underwent this treatment under pressure are shown in Table 1.

[0088] Example 1.5

[0125] The treatment of the flax fibres was carried out at a pressure of 820 kPa (8.2 bar) and a temperature of 170°C, and the solvent comprised water, 2.5% sodium sulphite and 0.83% sodium carbonate.

[0089]

[0126] The treatment under pressure that makes it possible to obtain individualized flax fibers is similar to that described in Example 1.4, with the difference that the solvent contains water, 2.5% sodium sulfite, and 0.83% sodium carbonate, the solvent / fiber mixture is heated to 170°C for 14 minutes, and the pressure is 850 kPa (8.5 bar).

[0090] Example 1.6

[0127] The treatment of the hemp fibres is carried out at a pressure of 700 kPa (7 bar) and a temperature of 164°C, and the solvent is pure water.

[0091]

[0128] The protocol is similar to that described in Example 1.1, with the difference being that flax fibers are replaced with hemp fibers.

[0092] Example 1.7

[0129] The treatment of the hemp fibres was carried out at a pressure of 820 kPa (8.2 bar) and a temperature of 170°C, and the solvent included water, 7.5% sodium sulphite and 2.5% sodium carbonate.

[0093]

[0130] The protocol is similar to that described in Example 1.4, with the difference being that flax fibers are replaced with hemp fibers.

[0094] Comparative Example of Example 1

[0131] Flax fibers that have not been treated under pressure.

[0095]

[0132] In this comparative example of Example 1, flax fibers undergo the following treatment: The flax fibers are cut so that the bundles have a length of 8 mm. The cut flax fibers and the solvent, i.e., water, are mixed in a reactor operating at a temperature such that the ratio of the dry weight of the flax fibers to the volume of the water is 0.05. The solvent / fiber mixture is heated to 70°C and the pressure is atmospheric. The temperature of 70°C is maintained for 20 minutes. After this treatment, the flax fibers are separated from the solvent and dried at 80°C for 16 hours.

[0096] Example 2

[0133] Characterization of flax fibers obtained during Examples 1.1 to 1.5 and Comparative Example 1.

[0097] Example 2.1

[0134] Cellulose, hemicellulose, and lignin contents in flax fibers

[0135] The cellulose and hemicellulose contents in flax fibers are measured according to the above-mentioned SCAN-CM71.

[0098]

[0136] The lignin content in the flax fibers is determined as described above.

[0137] The cellulose, hemicellulose, and lignin contents of flax fibers subjected to the treatments of Examples 1.1 to 1.5 and the comparative example of Example 1 are shown in Table 1.

[0099]

[0138]

[0100] [Table 1]

[0101]

[0139] Table 1 shows that the flax fibers that have undergone treatment under pressure have the specific cellulose, lignin and hemicellulose content of the individualized flax fibers of the present invention, relative to the dry weight of the flax fibers.The flax fibers obtained in the comparative example of Example 1 have a cellulose content of less than 80% according to Table 1, that is, they deviate from the specific cellulose content of the individualized flax fibers of the present invention.

[0102] Example 2.2

[0140] Optical microscope observation of flax fibers

[0141] The flax fibers obtained in Examples 1.1 to 1.5 and the comparative example of Example 1 are pulped at a concentration of 3 g / L for 3 minutes and then kept in suspension for 20 minutes.

[0103]

[0142] The flax fibers thus treated are then observed under an optical microscope.

[0143] Figures 1 to 6 show optical microscope images of the fibers.

[0144] Figures 1 to 5 show that the flax fibres obtained in Examples 1.1 to 1.5 are individualised, and in fact no fibre bundles are visible in Figures 1 to 5. Furthermore, Figures 1 to 5 show that these individualised flax fibres are flexible, as they are curved.

[0104]

[0145] On the contrary, some flax fiber bundles can be seen in Figure 6. This Figure 6 therefore illustrates that the flax fibers obtained in the comparative example of Example 1 are not individualized. Furthermore, these flax fibers are not flexible because they are grouped together to form bundles.

[0105] Example 3

[0146] Entangled nonwoven substrate according to the present invention

[0106] Example 3.1

[0147] Substrate containing 15% flax fibers, 5% lyocell fibers, and 80% wood fibers obtained in Example 1.1.

[0107]

[0148] The flax fiber obtained in Example 1.1, wood fiber (Sodra Black 85Z), and Lyocell fiber (10 mm, 1.7 dTex) are mixed to obtain a fiber mixture, which is then passed over a drainage gauze to obtain a nonwoven substrate.

[0108]

[0149] The nonwoven substrate then undergoes a hydroentanglement treatment by passing under two injection rails, each having a strip containing two rows, at a pressure of 2000 kPa (20 bar).

[0109]

[0150] The nonwoven substrate has a basis weight of 60 g / m 2 It has.

[0110] Example 3.2

[0151] Substrate containing 15% flax fibers, 5% lyocell fibers, and 80% wood fibers obtained in example 1.2.

[0111]

[0152] The protocol is similar to that described in Example 3.1, with the difference being that the flax fibers obtained in Example 1.1 are replaced by the flax fibers obtained in Example 1.2.

[0112]

[0153] The nonwoven substrate has a basis weight of 60 g / m 2 It has.

[0113] Example 3.3

[0154] Substrate containing 15% flax fibers, 5% lyocell fibers, and 80% wood fibers obtained in example 1.4.

[0114]

[0155] The protocol is similar to that described in Example 3.1, with the difference being that the flax fibers obtained in Example 1.1 are replaced by the flax fibers obtained in Example 1.4.

[0115]

[0156] The nonwoven substrate has a basis weight of 60 g / m 2 It has.

[0116] Example 3.4

[0157] Substrate containing 20% ​​flax fibers and 80% wood fibers obtained in example 1.4.

[0117]

[0158] The protocol is similar to that described in Example 3.1, with the difference that the flax fibers obtained in Example 1.1 are replaced by the flax fibers obtained in Example 1.4 and no lyocell fibers are added.

[0118]

[0159] The nonwoven substrate has a basis weight of 60 g / m 2 It has.

[0119] Example 3.5

[0160] Substrate containing 50% flax fibers, 5% lyocell fibers, and 45% wood fibers obtained in example 1.4.

[0120]

[0161] The protocol is similar to that described in Example 3.1, with the difference being that the flax fibers obtained in Example 1.1 are replaced by the flax fibers obtained in Example 1.4.

[0121]

[0162] The nonwoven substrate has a basis weight of 60 g / m 2 It has.

[0122] Example 3.6

[0163] Substrate containing 55% flax fibers and 45% wood fibers obtained in example 1.4.

[0123]

[0164] The protocol is similar to that described in Example 3.1, with the difference that the flax fibers obtained in Example 1.1 are replaced by the flax fibers obtained in Example 1.4 and no lyocell fibers are added.

[0124]

[0165] The nonwoven substrate has a basis weight of 60 g / m 2 It has.

[0125] Example 3.7

[0166] Substrate containing 20% ​​hemp fibers and 80% wood fibers obtained in example 1.6.

[0126]

[0167] The protocol is similar to that described in Example 3.1, with the difference being that the flax fibers obtained in Example 1.1 are replaced with hemp fibers obtained in Example 1.6 and no lyocell fibers are added.

[0127]

[0168] The nonwoven substrate has a basis weight of 60 g / m 2 It has.

[0128] Example 3.8

[0169] Substrate containing 20% ​​hemp fibers and 80% wood fibers obtained in example 1.7.

[0129]

[0170] The protocol was similar to that described in Example 3.1, with the difference that the flax fibers obtained in Example 1.1 were replaced with hemp fibers obtained in Example 1.7 and no lyocell fibers were added.

[0171] The nonwoven substrate has a basis weight of 60 g / m 2 It has.

[0130] Comparative Example of Example 3

[0172] Substrate containing 15% flax fibers, 5% lyocell fibers and 80% wood fibers obtained in the comparative example of Example 1.

[0131]

[0173] The protocol is similar to that described in Example 3.1, with the difference being that the flax fibers obtained in Example 1.1 are replaced by the flax fibers obtained in the comparative example of Example 1.

[0132]

[0174] The nonwoven substrate has a basis weight of 60 g / m 2 It has.

[0133] Example 4

[0175] Characterization of Examples 3.1 to 3.8, Comparative Example Substrate of Example 3, and Control Substrate.

[0134] Example 4.1

[0176] Dry tensile strength.

[0177] Dry tensile strength is measured for the substrates of Examples 3.1 to 3.8 and compared to a control substrate containing 20% ​​lyocell fibers and 80% wood fibers (Sodra Black 85Z) and the comparative substrate of Example 3.

[0135]

[0178] The dry tensile strength is measured according to the EN 29073-3 method (1992).

[0179] The results are presented in Figure 7 and show that whatever the content of individualized bast fibers and whatever the nature of the bast fibers, all substrates have dry tensile strengths of the same order of magnitude.

[0136] Example 4.2

[0180] Wet tensile strength.

[0181] Wet tensile strength is measured according to ISO 12625-5 method (2017) for the substrates of Examples 3.1 and 3.3 to 3.8 and compared to a control substrate containing 20% ​​lyocell fiber and 80% wood fiber (Sodra Black 85Z) and the comparative substrate of Example 3.

[0137]

[0182] The wet tensile strength of all substrates is satisfactory and of the same order of magnitude whatever the content of individualized bast fibers and whatever the nature of the bast fibers.

[0138] Example 4.3

[0183] distortion.

[0139]

[0184] The distortion is measured for the four example substrates and the control substrate.

[0185] The distortion is measured according to the EN 29073-3 method (1992).

[0186] The results are presented in Figure 8 and show that all substrates have the same magnitude of distortion.

[0140] Example 4.4

[0187] Optical microscope observation of the substrates of Example 3.3 and Comparative Example 3.

[0188] 9 and 10 show optical microscope images of the substrate of Comparative Example 3.3 and the comparative substrate of Example 3, respectively (optical zoom X200).

[0141]

[0189] Figure 9 shows that the substrate of Comparative Example 3.3 does not contain any flax fiber bundles, whereas flax fiber bundles are found in the substrate of Comparative Example 3 (circled in Figure 10).

[0190] Furthermore, the fibers of the substrate of Example 3.3 exhibit better entanglement than the fibers of the substrate of the comparative example of Example 3.

[0142]

[0191] These results are characteristic of the individualization and softness of the flax fibers of the substrate of Example 3.3.

[0143] Example 4.5

[0192] Sensory evaluation of the substrates of Examples 3.1 to 3.3, 3.7, 3.8, and the comparative example of Example 3.

[0144]

[0193] The sensory properties of the substrates of Examples 3.1 to 3.3, 3.7, 3.8 and the comparative example of Example 3 are evaluated by a cosmetic research panel consisting of several panelists.

[0194] For each substrate, each panelist judges softness, color, tear strength, and unfoldability.

[0145]

[0195] The substrates of Examples 3.1 to 3.3, 3.7 and 3.8 are soft to the touch and have very natural colours, with the softest being the substrate of Example 3.3.

[0196] The substrate of the comparative example of Example 3 is not soft, as small particles corresponding to fiber bundles are visible.

[0146]

[0197] The substrates of Examples 3.1, 3.3, 3.7, 3.8 and the comparative example of Example 3 do not tear apart when torn by hand.

[0198] All substrates tested spread well. Specific embodiments of the present invention are as follows. [Aspect 1] A nonwoven substrate, 40% to 95% by weight of wood fibers based on the total weight of fibers in the substrate; and 5% to 60% by weight of individualized bast fibers based on the total weight of the fibers of the substrate wherein the individualized bast fibers have a cellulose content of 80% or more, a hemicellulose content of 10% or less, and a lignin content of 9.5% or less, based on the dry weight of the individualized bast fibers. [Aspect 2] 2. The nonwoven substrate of embodiment 1, wherein the bast fibers are selected from hemp fibers, Indian hemp fibers, jute fibers, kenaf fibers, kudzu fibers, coinvine fibers, flax fibers, okra fibers, nettle fibers, papyrus fibers, ramie fibers, sisal fibers, esparto fibers, and mixtures thereof. [Aspect 3] 3. The nonwoven substrate of embodiment 1 or 2, also comprising additional fibers selected from lyocell fibers, viscose fibers, cellulose acetate fibers, biodegradable polymer fibers, and mixtures thereof. [Aspect 4] 4. The nonwoven substrate of embodiment 3, wherein the amount of additional fibers is 15 wt% or less, based on the total weight of fibers in the substrate. [Aspect 5] 5. The nonwoven substrate of any one of the preceding aspects, wherein the fibers are entangled. [Aspect 6] A wipe comprising the substrate of any one of embodiments 1 to 5. [Aspect 7] A method of making the nonwoven substrate of any one of aspects 1 to 4, comprising the steps of: a) treating bast fibers under pressure in a solvent to obtain the individualized bast fibers; b) mixing the individualized bast fibers with wood fibers to obtain a fiber mixture; and c) producing a nonwoven substrate from the fiber mixture by a wet-laid process, a dry-laid process, or an air-laid process; A method comprising: [Aspect 8] 8. The method of embodiment 7, wherein said treating step a) is carried out at a pressure between 500 kPa (5 bar) and 1000 kPa (10 bar). [Aspect 9] The method of any one of embodiments 7 to 8, wherein the temperature of the solvent during treating step a) is between 50° C. and 250° C. [Aspect 10] Aspect 10. The method of any one of aspects 7 to 9, wherein the solvent is an aqueous solvent. [Aspect 11] 11. The method of any one of aspects 7 to 10, wherein the solvent comprises an additive. [Aspect 12] 12. The method of embodiment 11, wherein the additive is an acid or a base. [Aspect 13] A method of producing a nonwoven substrate according to embodiment 5, wherein the nonwoven substrate produced during step c) of the method of any one of embodiments 7 to 12 undergoes an entanglement step d). [Aspect 14] A method of producing a wipe, comprising the step e) of cutting a substrate produced by the method of any one of aspects 7 to 13.

Claims

1. A method for producing a nonwoven substrate, comprising: 40% to 95% by weight of wood fibers, based on the total weight of fibers in the substrate; and 5% to 60% by weight of individualized bast fibers based on the total weight of the fibers of the substrate wherein the individualized bast fibers have a cellulose content of between 80% and 98%, a hemicellulose content of between 0.5% and 10%, and a lignin content of between 1% and 9.5%, based on the dry weight of the individualized bast fibers; The method comprises the steps of: a) treating bast fibers under pressure in a solvent to obtain the individualized bast fibers; b) mixing the individualized bast fibers with wood fibers to obtain a fiber mixture; and c) producing a nonwoven substrate from the fiber mixture by a wet-laid process, a dry-laid process, or an air-laid process; Including, the temperature of the solvent during the treatment step a) is between 160° C. and 200° C., said treatment step a) is carried out at a pressure between 500 kPa (5 bar) and 1000 kPa (10 bar); The method wherein the solvent is an aqueous solvent.

2. The method of claim 1, wherein the bast fibers are selected from hemp fibers, Indian hemp fibers, jute fibers, kenaf fibers, kudzu fibers, coinvine fibers, flax fibers, okra fibers, nettle fibers, papyrus fibers, ramie fibers, sisal fibers, esparto fibers, and mixtures thereof.

3. The method of claim 1 or 2, wherein the substrate also comprises additional fibers selected from lyocell fibers, viscose fibers, cellulose acetate fibers, biodegradable polymer fibers, and mixtures thereof.

4. The method described in claim 3, wherein the amount of additional fibers is 15 weight percent or less relative to the total weight of fibers in the substrate.

5. The method of claim 1 , wherein the solvent comprises an additive.

6. The method of claim 5 , wherein the additive is an acid or a base.

7. 7. The method of any one of claims 1 to 6, wherein the nonwoven substrate produced during step c) undergoes an entanglement step d).

8. The method of any one of claims 1 to 7, comprising the step e) of cutting the nonwoven substrate.

9. 9. The method of claim 8 for producing wipes.

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