Water-dispersible composite structure and method for producing the same

Abstract

To provide a water-dispersible composite structure including one or more layers, which can be recovered and recycled by using a device conventionally used in a paper and paperboard industry, and a manufacturing method thereof.SOLUTION: At least a part of layers is formed from a fiber web or a sheet which includes 50-90 pts.wt. of woody fibers, 10-90 pts.wt. of annual or perennial plant fibers, and 10-50 pts.wt. of synthetic short fibers, and 0.1-20 wt.% of binders calculated by weights of the fibers. At least a part of binders comprises a water-soluble polymer and the other parts comprise a water-dispersible binder, and the fiber sheet or the web is manufactured by wet molding.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for producing a fibrous material, such as a sheet-formed or web-formed layered material, from a fibrous raw material. Such materials are dispersed separately in an aqueous medium to form a structure in which at least some of the raw fiber is dispersed. More specifically, the present invention provides a method for producing a soluble polymeric compound which can be dispersed in an aqueous medium. The present invention also relates to a structure comprising fibers of natural and synthetic origin forming a composite material. , methods for making such materials, and methods for using them. [Background technology]

[0002] Dispersible nonwoven fabrics are known in the art. They are suitable for hygienic applications. It finds use as a dispersible and washable fiber.

[0003] US Patent No. 5,949,993 discloses water-dispersible formulations and materials and methods for influencing their water-dispersibility. The water-dispersible formulation comprises 1 to 90% by weight of at least one water-soluble cellulose. Additionally, the formulation comprises a cellulose ether binder. It contains at least about 10 to about 99% by weight of long cellulose fibers, each having a length of 1 meter or more. The literature suggests that water-soluble cellulose ether binders containing significant amounts of long cellulose fibers It is described that the water dispersibility of the formulation is increased by adding a gas-releasing agent. The speed can be increased.

[0004] Uses of the material in the medical and food industries are proposed.

[0005] Patent document 2 discloses an absorbent fabric-like structure for disposable purposes. It exhibits strength and durability that allows for practical use, but can be disposed of in sewer systems after use. The structure includes water-sensitive fibers having ionizable groups, and the material is, for example, cyanoethyl cellulose. The polymer may be selected from cellulose or hydroxyethyl cellulose.

[0006] Other flushable wet wipes are taught in US Pat. Nos. 5,623,999 and 5,723,999.

[0007] Patent Document 5 discloses a pulp-based composition that can be used for rapidly dispersing wet wipes. The solvent-spun fibers are, for example, Tencel (registered trademark). The patent application includes a variety of fibrillated cellulose, including wood pulp and Tencel®. A blend of short fibers was used to create a wet-laid fabric. The fibers were refined and 1% was added as a dispersing aid. CMC is added and an epichlorohydrin-based wet strength resin is added to increase wet strength. The slurry thus formed is then wet laid, for example, in a paper machine to form a sheet. The sheet is then passed through a hydroentanglement process, either online or in a separate offline process. This forms a woven fabric.

[0008] The resulting tissue is flushable through a standard toilet system and is biodegradable after processing. It is said to be decomposable into dispersible fragments that decompose.

[0009] The disclosed materials are dispersible in water, but they are not degradable and disposable materials (disposable materials). For this reason, known dispersive materials are designed for use as a corresponding They still lack strength and structural integrity when compared to non-degradable materials. As a result, their main use is that they are already completely degraded in wastewater and sewer systems. Therefore, the materials they contain are disposed of after use. It is discarded and cannot be recycled.

[0010] The use of hydroentanglement in the art is in the construction of materials and materials for recovery and recycling. It inhibits the repulping of the material.

[0011] Conventional recycling processes employed in the paper and board industry result in the formation of dispersed structures in the aqueous phase. It is possible to produce and recycle synthetic fiber fractions while still having good mechanical properties. There is a need for dispersible structural materials that [Prior art documents] [Patent documents]

[0012] [Patent Document 1] U.S. Patent No. 5,346,541 [Patent Document 2] U.S. Patent No. 3,563,241 [Patent Document 3] U.S. Patent No. 5,629,081 [Patent Document 4] European Patent Application Publication No. 1285985 [Patent Document 5] US Patent Application Publication No. 2014 / 0318726 Summary of the Invention [Problem to be solved by the invention]

[0013] The object of the present invention is to provide a method for manufacturing a laminated ... with at least one layer formed by a fibrous web or sheet, e.g. The present invention provides novel water-dispersible compositions and structures, including, for example, multiple overlapping layers.

[0014] Another object is to provide a method for producing such a composition.

[0015] A third object is to provide methods of using the compositions. [Means for solving the problem]

[0016] The present invention provides a fibrous layer containing wood fibers, natural and / or synthetic non-wood fibers, and a binder. Surprisingly, natural and / or Or provide a fiber composition containing at least 50% wood fiber mixed with synthetic fiber, and wet molding and a binder containing a water-soluble polymer and a water-dispersible polymer. to produce a water-dispersible sheet or web having mechanical properties by bonding I discovered that it is possible.

[0017] The material can be produced by wet molding by the following steps. - conveying the aqueous fiber slush to a support; - Draining the liquid through the support to form a fibrous layer - A binder is applied onto the fiber layer to at least partially bind the fibers together. The binder comprises an aqueous solution of a water-soluble polymer and further comprises a water-dispersible polymer. Contains.

[0018] The compositions and methods are used to provide nonwoven products such as nonwoven webs and nonwoven sheets. It is possible.

[0019] More specifically, the invention is mainly characterized by what is stated in the characterizing parts of the independent claims. do.

[0020] The present invention provides significant advantages. Thus, the material is comparable to typical paper, paperboard and In particular, the present invention provides a method for producing a polyester fiber having good mechanical properties that allow it to be used in fabrics and nonwoven applications. Nonwoven products selected from the group of webs and sheets can be prepared.

[0021] Additionally, the material may be dispersed in a conventional pulper of the type used in the paper or paperboard industry to produce a small amount of The structure of the material allows the wood fibers to be separated from the water-dispersible material without any additional effort. The fibers can be at least partially recovered and, if desired, recycled to produce fibrous materials and and other materials.

[0022] Wet forming can be carried out industrially, for example, on a nonwoven or paper machine.

[0023] without the need for mechanical bonding such as hydroentanglement or spunlacing , achieving an adhesive bond. [Brief explanation of the drawings]

[0024] [Figure 1] The photomicrograph shows a receiver of a reference material on the left and a single fiber of such material on the right. [Figure 2] On the left is a photomicrograph showing a recipient of a material according to the present technology and on the right is a single fiber of such a material. DETAILED DESCRIPTION OF THE INVENTION

[0025] Embodiments of the present technology will now be discussed in more detail with reference to the accompanying figures.

[0026] As mentioned above, the present technology is directed to the use of natural fibers, such as wood fibers in combination with natural or synthetic fibers. A composite structure in the form of a water-dispersible fibrous layer containing fibers is provided.

[0027] In one embodiment, in the water-dispersible composite structure, the fibrous web or sheet is primarily hydrogen-bonded. It comprises a network of fibers held together by interlocking and adhesive bonds.

[0028] The layers herein are referred to as "composite structures" in that they contain both natural and synthetic fibers. It is called the "body."

[0029] "Water-dispersible" when used in relation to book materials means that the fiber matrix is ​​broken down and This means that the constituent fiber materials can be separated from each other and from the material. or at least a portion of other natural fibers, for example at least 5% by weight, in particular at least 10% by weight % by weight, preferably at least 20% by weight, can be recovered and optionally recycled.

[0030] In one aspect, the water dispersibles are useful for recycling paper, cardboard and other fiber-based products. It relates to the properties of a material that can be industrially repulped under the conditions in which it is used. Typical conditions for low consistency (LC) pulping are 2-7% by weight consistency and temperatures of 30-60°C. The general conditions for pulping (HC) are a consistency of 10 to 35% by weight and a temperature of 30 to 60°C. Pulping time depends on industrial factors such as the size of the equipment and rotor used for slashing. Typically, the pulping process involves the initial material structure being adjusted to suit the application. The pulping process is carried out until the appropriate amount of fiber is obtained. These may contain chemicals such as sorbents, sodium silicate and surfactants.

[0031] According to one embodiment, the water-dispersible composite structure includes natural fibers in the form of "wood fibers." In one embodiment, such wood fibers include chemical pulp fibers, recycled fibers, mechanical pulp fibers, and bleached and unbleached pulp fibers selected from the group consisting of pulp fibers, semi-mechanical pulp fibers, and combinations thereof; It is selected from refined and unrefined fibres, in particular unrefined fibres.

[0032] Wood materials include birch, beech, poplars such as European poplar, alder, and eucalyptus. , maples, acacias, mixed tropical hardwoods, pines like loblolly pine, fir, hemlock, moss Larch, spruce such as black spruce or Norway spruce, and mixtures thereof. do.

[0033] One or more second fiber components of the composite structure are non-wood fibers. Such fibers include: It may be natural fiber, such as annual plant fiber, or synthetic fiber, or a combination thereof. Synthetic fibers are distinct from wood fibers and natural non-wood fibers, which are considered non-synthetic fibers in this specification. In contrast, it can also be characterized as "artificial."

[0034] Thus, in one embodiment, non-wood fibers are plant materials other than wood (natural non-wood (or Fibers obtained from "non-wood" materials and man-made fibers, such as synthetic fibers, especially polymers - fibers.

[0035] The non-wood fibres may be selected, for example, from the following group: - Annual or perennial plant fibres, such as hemp, flax, kenaf, bagasse, cotton, straw - Thermoplastic fibers, such as polylactic acid (PLA), glycolic acid polymer (PGA), Trihydroxyalkanoate (PHA), polyolefin (PO), polyethylene terephthalate Polyethylene terephthalate (PET), polyester (PES), polyvinyl alcohol (PVA) fibers - Bicomponent fibers containing thermoplastic polymers - Mineral fiber, glass fiber - Regenerated cellulose fibers such as viscose, lyocell, and rayon and combinations of fibers selected from two or more of the above groups.

[0036] In one embodiment, the non-wood fibers, especially synthetic fibers, are "short-cut" fibers. In this specification, "short fibers" refers to fibers having a length of 5 to 25 mm, particularly 6 to 18 mm. In one embodiment, these are fibers having a thickness of 0.5 dtex to 20 dtex, in particular 1 It may have a thickness of up to 15 dtex, for example a thickness of 1.5 to 10 dtex.

[0037] Annual or perennial plant fibers may be used as short fibers (as defined above) or as corresponding It exists as a fiber obtained by maceration, including mechanical, semi-mechanical or chemical maceration of plant material. There can be.

[0038] In one embodiment, the fibrous layer comprises 50 to 90 parts by weight of wood fibers and 0 to 90 parts by weight of, e.g. 10 to 90 parts by weight of annual or perennial plant fiber and 0 to 50 parts by weight, for example 10 to 5 0 parts by weight of synthetic short fibers or a combination thereof, The total amount of non-wood natural fibers and synthetic fibers is typically 10 to 50 parts by weight. .

[0039] In one embodiment, 50 to 99% by weight, in particular 60 to 90% by weight, of the fibers in the fibrous layer are cellulose. It is composed of cellulose fiber, lignocellulose fiber or a mixture thereof, and is 1 to 50 % by weight, particularly 10 to 40% by weight, is constituted by artificial fibers.

[0040] In one embodiment, 50 to 99% by weight, in particular 60 to 90% by weight, of the fibers in the fibrous layer are cellulose. It is composed of cellulose fiber, lignocellulose fiber or a mixture thereof, and is 1 to 50 % by weight, in particular 10 to 40% by weight, of non-wood fibers, such as fibers of annual or perennial plants. The material may be composed of natural fibers or such fibers in combination with artificial fibers.

[0041] In one embodiment, man-made fibers include regenerated cellulose fibers, synthetic fibers, synthetic thermoplastic fibers, and A mixture of these is selected from the group.

[0042] Regenerated cellulose fibers include viscose fibers, lyocell fibers, rayon fibers, and mixtures thereof. The thermoplastic fibers may be selected from the group consisting of polyolefin fibers, polyester fibers, and and biopolymer fibers, and mixtures thereof.

[0043] In one embodiment, annual and other non-wood natural (typically plant) fibers are found in the cereal crops. Straw, reed grass, reed, hemp, hemp, kenaf, jute, potato hemp, seeds, sisal, maize Chive hemp, coir, bamboo, bagasse, cotton kapok, milkweed, pineapple, cotton, rice, reed, african The plant is selected from the group consisting of scutellaria, reed canarygrass, and combinations thereof. The non-wood fibers are selected from the group consisting of seed hair fibers, leaf fibers and bast fibers.

[0044] In one embodiment, the composite structure comprises a dry weight of the binder and a dry weight of the fiber portion of the fiber layer. It further contains about 0.1 to 20% by weight calculated based on the above.

[0045] The term "binder" as used herein means a material that binds fibers together, e.g., to form a fiber network. The term "binder" refers to a single substance that can contribute to the formation of a binder. It refers to both substances and mixtures of substances.

[0046] In one embodiment, the present invention includes a combination of a water-soluble polymer and a water-dispersible polymer. Water-soluble polymers are typically hydrophilic polymers, while water-dispersible polymers are typically It is a hydrophobic polymer.

[0047] In one embodiment, the binder is polyvinyl alcohol, polyvinyl acetate dispersion, ethyl acetate, vinyl alcohol dispersion, polyurethane dispersion, acrylic latex, styrene butadiene Ene dispersions, binders based on fine cellulose, binders based on cellulose derivatives , biopolymers such as biopolymers based on starch derivatives, natural rubber latex, alginate Phosphates, guar gum, hemicellulose derivatives, chitin, chitosan, pectin, agar, chitin Amylose, amylopectin, alternan, gellan, mutan, dextran , pullulan, fructan, locust bean gum, carrageenan, glycogen, glyco Aminoglycans, murein, bacterial capsular polysaccharides, and the like, and combinations thereof is selected from the group consisting of:

[0048] One embodiment includes a method of using a binder comprising the following combination: - of a binder formed by a water-soluble polymer or a mixture of such polymers First part - a second part of the binder formed by a water-dispersible polymer or polymer mixture;

[0049] In one embodiment, the first portion (a water-soluble polymer or a mixture of such polymers) a second part (formed by a water-dispersible polymer or polymer mixture) and a third part (formed by a water-dispersible polymer or polymer mixture). ) is 1:20 to 20:1, particularly 1:10 to 10:10, for example 1.5: It's 10:00~2:20.

[0050] Binders containing both water-soluble and water-dispersible polymers are suitable for use in water-dispersible sheets or At least a portion, preferably a majority, especially of the total binder used to form the fibrous layers of the web % by weight, preferably 90 to 100% by weight.

[0051] As mentioned above, water-dispersible composite structures are primarily interconnected through hydrogen bonding and adhesive bonding. However, the properties of the fiber network, particularly its chemical or physical properties or their Other ingredients may also be present that modify the properties of both.

[0052] In one embodiment, the fibrous web or sheet is coated with a sizing agent, particularly a reactive sizing agent. Examples of such agents include alkyl ketene dimers (conventionally abbreviated as "AKD"). ") and alkenyl succinic anhydrides ("ASA").

[0053] The sizing agent can be added separately. However, in one embodiment, the sizing agent The agent is mixed with one or more binders.

[0054] The sizing agent is used in an amount of 0.01 to 10%, especially 0.1 to 5%, depending on the dry weight of the fiber layer. For example, it can be added in an amount of 0.15 to 3%.

[0055] In one embodiment, the composition comprises wood fibers, short fibers, and a binder or binder composition. The method for making a water-dispersible composite structure containing layers includes the following steps. - The aqueous fiber slush is applied to a perforated support, i.e., a conventional wire for wet forming, Carrying steps - Draining the liquid through the perforated support to form a fibrous layer. - Applying a binder onto the fiber layer to at least partially bind the fibers together Top.

[0056] Typically, in the fibrous layer, the fibers are held together by hydrogen bonding and / or adhesive bonding. Form.

[0057] In one embodiment, the fibrous layer is optionally dried and optionally calendered to form a fibrous layer. A fibrous web or sheet is formed.

[0058] In one embodiment, the above method is carried out on a paper or board machine or a wetlaid nonwoven machine.

[0059] Typically, this treatment does not involve any hydroentangling step.

[0060] In one embodiment, the binder is applied onto the fibrous layer as a foamable aqueous composition. The composition comprises an aqueous solution of a water-soluble polymer that further contains a dispersed water-dispersible polymer. It is possible.

[0061] In one embodiment, the fiber slashes fed onto a wire or other foraminous support are and synthetic or natural non-woven fabrics, together with cellulose fibers, lignocellulosic fibers, or mixtures thereof. The concentration of the aqueous slush may be, for example, 0.01 to 1.0001g. 5% by weight, particularly 0.1 to 2% by weight.

[0062] In one embodiment, the binder composition comprises a dry matter of the binder and a dry matter of the fibrous portion of the fibrous layer. 0.1 to 20% by weight, e.g., 0.1 to 15% by weight, of the binder, calculated on dry matter %, particularly 1.5 to 10% by weight.

[0063] In one embodiment, the binder is applied onto the fibrous layer in a "predetermined" manner. The binder is applied to the fiber layer either before or only after drying to the final dry state. It is possible.

[0064] In one embodiment, the binder is applied onto a fibrous layer having a moisture content of 90-10%. .

[0065] In one embodiment, the binder is applied onto a fibrous layer having a moisture content of about 85 to 65% by weight. In another embodiment, the binder is applied to a fibrous layer having a moisture content of about 2 to 10% by weight. is applied to the

[0066] In one embodiment, a binder is applied onto the fibrous layer before the fibrous layer is pressed. This type of pressing removes moisture before further drying and calendaring. .

[0067] In one embodiment, the binder is typically present at a content of less than about 10% by weight, regardless of application time. The coating is applied onto the fibrous layer having a water content using a doctor blade or a coating roll. In another embodiment, the binder is applied to a fibrous layer, typically having a moisture content of 60% by weight or greater. The adhesive is applied to the substrate by vacuum enhancement, non-contact application, or a combination thereof.

[0068] The binder is applied to at least one side, preferably both sides, of the fibrous layer, or alternatively Alternatively or additionally, the coating may be applied using suction or reduced pressure ("vacuum").

[0069] As mentioned above, a "binder" can include one or more substances. It can be applied as an aqueous solution or as an aqueous dispersion, or as a mixture thereof. Cut.

[0070] In one embodiment, the binder is present in an amount of 1 to 50% by weight, for example 1 to 30% by weight, in particular 2.5 an aqueous composition having a dry matter content of up to 25% by weight, the aqueous composition comprising at least It contains one water-soluble polymer and at least one water-dispersible polymer.

[0071] In one embodiment, the binder comprises at least one water-soluble polymer and at least one in a weight ratio of 1:20 to 20:1, particularly 1:10 to 10:10. The weight ratio is calculated based on the dry weight of the polymer.

[0072] Of the binders listed above, particularly advantageous species are polyvinyl alcohol, polyacetic acid, Vinyl dispersion, ethyl vinyl alcohol dispersion, polyurethane dispersion, acrylic latex styrene butadiene dispersions, binders based on fine cellulose, cellulose derivatives and combinations and mixtures thereof. The polymer is represented by

[0073] Thus, in one embodiment, the binder is a water-soluble polymer dissolved in water. by forming an aqueous solution of the water-dispersible polymer and then dispersing the water-dispersible polymer in the aqueous solution. The resulting aqueous composition is:

[0074] The binder may comprise an aqueous composition prepared, for example, by the steps of: First, from the group of polyvinyl alcohol and polyvinyl acetate and their combinations, At least one water-soluble polymer selected from the group consisting of and dissolving the polymer in water at ambient pressure at room temperature to form an aqueous solution of the polymer. polyurethane dispersion, acrylic latex, styrene butadiene dispersion, binder group At least one polymer selected from the group consisting of: Dispersing step.

[0075] The binder composition is prepared by intensively mixing the aqueous phase and optionally applying shear. The mixing can be carried out in a mixer or a disperser.

[0076] Preferably, the binder is provided as a stable dispersion.

[0077] In one embodiment, a "stable dispersion" is one in which no sedimentation occurs from the dispersion when left at room temperature for 24 hours. This means that the weight of dispersed solids is less than 20%, in particular less than 10%, preferably less than 5%. Taste.

[0078] In one embodiment, the dispersion further comprises a dispersing agent. Such a dispersing agent is used to disperse the dispersed solids. It may be present in an amount of up to 5%, especially up to 2.5%, by weight of the material.

[0079] In one embodiment, dispersing the water-dispersible polymer in an aqueous solution of the water-soluble polymer. The binder composition obtained by is then foamed and applied onto the fibrous layer.

[0080] Depending on the binder actually used, a surfactant or a foaming agent may be added to foam the composition. The surfactant or foaming agent can be added in an amount of 0.01 to 15% by weight, particularly 0.01 to 15% by weight, based on the dispersion. It may be added in an amount of 1 to 10% by weight. However, in one embodiment, the aqueous composition It foams in the absence of surfactants.

[0081] In one embodiment, the foamable binder composition comprises 40 to 80% by volume, particularly 55 to 75% by volume. This includes gases, especially air.

[0082] The water-dispersible composite structure typically has a density of 10 to 250 g / m 2 , especially about 20-200g / m 2 Such fibrous webs or sheets include fibrous webs or sheets having a basis weight of Preferably it is selected from the group of nonwoven webs or paper webs and sheets.

[0083] The material produced by this technology has excellent properties. Therefore, after preparation, it is possible to produce a fiber sheet or wafer. The fiber is partially achieved by hydrogen bonding between the fibers and partially by adhesive bonding between the fibers. It exhibits good mechanical properties and does not require hydroentangling or spunlacing.

[0084] As mentioned above, compositions of this type are preferably used in the paper and paperboard industry as conventionally used. It is decomposable in the pulper.

[0085] Thus, in one embodiment, the fibrous web or sheet is slushed into an aqueous medium. In one embodiment, the fibrous web or sheet is dispersed at a temperature of 10 to 75°C and H6-8, typically at a concentration of 1-40 wt %, for example 2-35 wt %, in an aqueous medium such as water. It can be distributed throughout the body.

[0086] As the examples discussed below show, the binder in the material is easily broken down during pulping. As a result, fibers are released that can be recovered and recycled.

[0087] The following non-limiting examples illustrate embodiments of the present technology. [Example]

[0088] In this example, the binder of the water-soluble polymer, the water-dispersible polymer, and the hydrophobic agent according to the present technology was One embodiment of a post-consumer simulation of a fiber matrix bonded with a pyrotechnic system is shown in Figure 1. The evaluation was carried out in a wireless environment.

[0089] For the test, 450 kg of fiber matrix to be bonded with the binder system was placed in a pilot wet The fiber matrix of the present invention was prepared using the following fiber components and binder system: Includes.

[0090] Fiber Content: - Bleached softwood pine kraft pulp, unrefined: 60% by weight of the fiber matrix - Artificial fibres, 6 mm long and 1.7 dtex thick: 30% by weight of the fibre matrix

[0091] Binders: - Water-dispersible polymer: 12% by weight of the binder system - Water soluble: 4% by weight of the binder system - Hydrophobic agent: 1.00% by weight of the binder system

[0092] After manufacturing, this material was passed through an OptiSl rotor containing a JP rotor and a φ20 mm screen plate. The paper was repulped in a ushBale pulper under the following conditions: - Concentration: 7.45% - Temperature: 45°C - Duration: 20 minutes - pH: 6.9 - Energy consumption: 59.4 kWh / ton

[0093] The amount of Somerville flake (TAPPI T275) was 35.3%. This corresponds to the amount of synthetic fibers and water-dispersible polymers. It was shown that the pulp fibers were dissolved in the repulping system. By sorting, it can be separated from other components and recycled into new consumer products, namely paper. [Example]

[0094] In this example, the post-consumer fiber matrix having the same components and component occupancy as in Example 1 was One embodiment of the simulation was performed using pure softwood decomposed from dried unrefined softwood pulp. compared with a fiber suspension.

[0095] The produced fiber matrix and reference dry softwood fiber sheet were subjected to PTS method PTS-RH02 1 / 97, the pulp was decomposed in a British pulp disintegrator manufactured by Lorentzen & Wettre ( 40°C, 10 minutes, 3000 rpm).

[0096] The degraded fiber matrix suspension and the reference softwood fiber suspension were analyzed under an optical microscope (Axiop The microscope images were obtained using a fluoroscopy system (Carl Zeiss-EL Ensatz). The image shows that the binder system of the unsorted decomposed fiber matrix suspension is already partially dissolved. (Fig. 1) and shows that the quality of softwood pulp fiber is equivalent to that of softwood fiber (Fig. 2).

[0097] <References> Patent documents U.S. Patent No. 5,346,541 U.S. Patent No. 3,563,241 U.S. Patent No. 5,629,081 European Patent Application Publication No. 1285985 U.S. Patent Application Publication No. 2014 / 0318726

Claims

1. A water-dispersible composite structure comprising a fibrous layer, at least a part of the fibrous layer is formed by a fibrous sheet containing 50 to 90% by weight of wood fibres, 10 to 50% by weight of non-wood fibres and 0.1 to 20% by weight of a binder calculated from the weight of the fibres in the fibrous layer, at least a part of the binder being a water-soluble polymer; - said fibrous sheet is produced by a wet moulding technique, the binder is selected from the group consisting of polyvinyl alcohol, polyvinyl acetate dispersions, ethyl vinyl alcohol dispersions, polyurethane dispersions, acrylic latex, styrene butadiene dispersions, fine cellulose-based binders, cellulose derivative-based binders, biopolymers, combinations thereof, and mixtures thereof; a first portion of the binder formed by a water-soluble polymer or polymer mixture, a second portion of the binder formed by a water-dispersible polymer or polymer mixture, and the fibrous sheet is dispersible in a pulper conventionally used in the paper or paperboard industry; Here, the fiber sheet being dispersible means that it can be dispersed in an aqueous medium at a temperature of 10 to 75°C and a pH of 6 to 8 at a concentration of 1 to 40% by weight, and at least 5% of the total fibers can be recovered. Water-dispersible composite structure.

2. 10. The water-dispersible composite structure of claim 1, wherein the wood fibers are bleached or unbleached, refined or unrefined fibers selected from the group of chemical pulp fibers, mechanical pulp fibers, and semi-mechanical pulp fibers, and combinations thereof.

3. the non-wood fibers are selected from the group consisting of natural non-wood fibers and artificial fibers; - Annual or perennial plant fibres, including at least one of hemp, flax, kenaf, bagasse, cotton and straw, and combinations thereof. Thermoplastic fibers, polylactic acid (PLA), glycolic acid polymers (PGA), polyhydroxyalkanoates (PHA), polyolefins (PO), polyethylene terephthalate (PET), polyesters (PEs), and polyvinyl alcohol (PVA). - bicomponent fibres containing thermoplastic polymers - Mineral fibre, glass fibre - regenerated cellulose fibers, including at least one of viscose fibers, lyocell fibers, and rayon fibers; - a combination of fibers selected from two or more of the above groups 3. The water-dispersible composite structure according to claim 1, wherein the water-dispersible composite structure is selected from the group consisting of:

4. 4. The water-dispersible composite structure according to claim 1, wherein the non-wood fibers are short fibers having a length of 5 to 25 mm and a thickness of 0.5 dtex to 20 dtex.

5. The water-dispersible composite structure of any one of claims 1 to 4, wherein the fibrous sheet comprises a network of fibers held together primarily by hydrogen or adhesive bonds.

6. The water-dispersible composite structure according to any one of claims 1 to 5, wherein the fibrous sheet further contains a reactive sizing agent containing an alkyl ketene dimer or an alkenyl succinic anhydride.

7. The water-dispersible composite structure of claim 6 , wherein said reactive sizing agent is mixed with one or more of said binders.

8. The water-dispersible composite structure according to any one of claims 1 to 7, wherein the fibrous sheet is dispersible in an aqueous medium during slashing.

9. The water-dispersible composite structure according to any one of claims 1 to 8, comprising the fibrous sheet having a basis weight of 10 to 250 g / m2.

10. A water-dispersible composite structure described in any one of claims 1 to 9, comprising the fiber sheet being a nonwoven fabric sheet.

11. A method for producing a water-dispersible composite structure containing a layer containing wood fibers, non-wood fibers, and a binder by wet molding, comprising: - conveying an aqueous fiber slush containing wood fibers and non-wood fibers to a foraminous support; - draining the liquid through the foraminous support to form a fibrous layer; applying a binder onto the fibrous layer to at least partially bind the fibers in the fibrous layer; the binder comprises an aqueous solution of a water-soluble polymer which further contains a water-dispersible polymer; the binder is selected from the group consisting of polyvinyl alcohol, polyvinyl acetate dispersions, ethyl vinyl alcohol dispersions, polyurethane dispersions, acrylic latex, styrene butadiene dispersions, binders based on finely divided cellulose, binders based on cellulose derivatives, biopolymers, combinations thereof, and mixtures thereof; - the water-dispersible composite structure is dispersible in pulpers conventionally used in the paper or paperboard industry; Here, the water-dispersible composite structure being dispersible means that it can be dispersed in an aqueous medium at a temperature of 10 to 75°C and a pH of 6 to 8 at a concentration of 1 to 40% by weight, and at least 5% of the total fibers can be recovered. method.

12. applying the binder as a foamable aqueous composition onto the fibrous layer; 12. The method of claim 11, wherein the foamable aqueous composition comprises an aqueous solution of a water-soluble polymer further containing a dispersed water-dispersible polymer.

13. The aqueous fiber slush comprising cellulosic fibers, lignocellulosic fibers, or mixtures thereof, as well as man-made fibers and natural non-wood fibers; 13. The method of claim 11 or 12, wherein the aqueous fiber slush has a consistency of 0.01 to 6% by weight.

14. The method of any one of claims 11 to 13, wherein the wet forming is carried out on a paper or board machine, or a wet nonwoven machine.

15. The method according to any one of claims 11 to 14, wherein the binder is applied onto the fibrous layer before the fibrous layer is dried to final drying.

16. 16. The method according to any one of claims 11 to 15, wherein the binder is applied onto the fibrous layer having a moisture content of 99 to 10% by weight.

17. The method of any one of claims 11 to 16, comprising drying and calendering the fibrous layer to form the water-dispersible composite structure.

18. 18. The method according to any one of claims 11 to 17, wherein the binder is applied onto the fibrous layer by means of a doctor blade, by means of an applicator roll, by vacuum intensification or by non-contact application to at least one side of the fibrous layer.

19. 19. The method according to any one of claims 11 to 18, wherein a water-dispersible polymer is dispersed in an aqueous solution of a water-soluble polymer and the composition thus obtained is foamed to obtain said binder.

20. 20. The method according to any one of claims 11 to 19, wherein the binder comprises the aqueous solution having a dry matter content of 1 to 50% by weight.

21. 21. The method according to any one of claims 11 to 20, wherein the binder contains at least one water-soluble polymer and at least one water-dispersible polymer in a weight ratio of 1:20 to 20:1 calculated on the dry matter of the polymers.

22. 22. The method of any one of claims 11 to 21, wherein the binder is an aqueous solution obtained by dissolving a water-soluble polymer in water to form an aqueous solution of the polymer, and subsequently dispersing a water-dispersible polymer in the aqueous solution.

23. The binder is dissolving at least one water-soluble polymer selected from the group consisting of polyvinyl alcohol and polyvinyl acetate, and combinations thereof, in water at a temperature of 10-100°C and at ambient pressure to form an aqueous solution of said polymer; subsequently dispersing at least one polymer selected from the group of polyurethane dispersions, acrylic latexes, and styrene butadiene dispersions into said solution at a temperature of 20-100°C at ambient pressure; The method according to any one of claims 11 to 22, wherein the aqueous solution is prepared by

24. A method according to any one of claims 11 to 23, comprising providing the binder as a stable dispersion.

25. The method of any one of claims 11 to 24, comprising mixing a reactive sizing agent comprising an alkyl ketene dimer or an alkenyl succinic anhydride with a binder.

26. The method of claim 12, comprising foaming the foamable aqueous composition in the absence of a surfactant.

27. 50 to 99% by weight of the fibers in the fiber layer are composed of the cellulose fibers, the lignocellulose fibers, or a mixture thereof; 14. The method of claim 13, wherein 1 to 50% by weight is constituted by said natural non-wood fibers or said artificial fibers or a combination thereof.

28. The wood fibers are bleached or unbleached, refined or unrefined fibers selected from the group consisting of chemical pulp fibers, mechanical pulp fibers, and semi-mechanical pulp fibers, and combinations thereof; 14. The method of claim 13, wherein the wood fibers are selected from the group consisting of essentially unrefined cellulose fibers, lignocellulosic fibers, and combinations thereof.

29. 14. The method of claim 13, wherein the man-made fibers are selected from the group of regenerated cellulose fibers, synthetic fibers, synthetic thermoplastic fibers, and mixtures thereof.

30. 30. The method of claim 29, wherein the regenerated cellulose fibers are selected from the group of viscose fibers, lyocell fibers, rayon fibers, and mixtures thereof.

31. 14. The method of claim 13, wherein the natural non-wood fibers are selected from the group of annual or perennial fibers including hemp, flax, kenaf, bagasse, cotton and straw, and combinations thereof.

32. The method of claim 29, wherein the synthetic thermoplastic fibers are selected from the group consisting of polyolefin fibers, polyester fibers and biopolymer fibers, and mixtures thereof.

33. A method according to any one of claims 11 to 32, comprising applying 0.1 to 20% by weight of binder calculated on dry matter of the fibrous layer.

34. A method according to any one of claims 11 to 33, comprising producing said water-dispersible composite structure having a basis weight of from 10 to 250 g / m2.

35. The method of any one of claims 11 to 34, wherein the fibers in the fibrous layer form a fibrous network by hydrogen bonding or adhesive bonding.

36. A method of using a method according to any one of claims 11 to 35 for the preparation of a nonwoven product selected from the group of nonwoven fabric sheets or paper sheets.

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