FIELD OF THE INVENTION

The present application relates to a fiber reinforced composition and the use thereof. Further, the present application relates a method for producing a reinforcing constituent of fibers. Further, the present application relates a reinforcing constituent of fibers and the use thereof. Further, the present application relates to fibers.

BACKGROUND

A composite refers to a material consisting of two or more individual constituents. A reinforcing constituent is embedded in a matrix to form the composite. Common composites are composed of glass or carbon fiber in a plastic resin. However, disposal of e.g. glass fiber after its use in different applications is challenging. Recycling the glass fiber reinforced composite material may also not be an alternative. One alternative is to burn the glass fiber reinforced composite after its use. However, burning glass fiber may adversely affect the apparatuses used for the burning process. Another alternative is that the glass fiber is simply being disposed to a landfill. However, this is not a beneficial alternative from an environmental perspective. Thus, as the reuse or disposal of the glass fiber after its use in end products has such challenges, it may be foreseen that the use thereof e.g. as a reinforcing constituent material may be prohibited in the future by legislation.

The inventors have, therefore, recognized the need for a fiber reinforced composition, that could e.g. be recycled after its use in end products or that could be disposed without an adverse impact on the environment or on the equipment used for the recycling process .

PURPOSE

The purpose is to provide a new type of a fiber reinforced composition and the use thereof. Further, the purpose is to provide a method for producing a reinforcing constituent of fibers. Further, the purpose is to provide a reinforcing constituent of fibers and the use thereof. Further, the purpose is to provide fibers.

SUMMARY

The fiber reinforced composition according to the present application is characterized by what is presented in claim 1.

The method for producing a reinforcing constituent of coated fibers according to the present application is characterized by what is presented in claim 8.

The reinforcing constituent of fibers according to the present application is characterized by what is presented in claim 14.

The fibers according to the present application are characterized by what is presented in claim 16.

The use of the reinforcing constituent of fibers according to the present application is characterized by what is presented in claim 18.

The use of the fiber reinforced composition according to the present application is characterized by what is presented in claim 19.

DETAILED DESCRIPTION

The present application relates to a fiber reinforced composition comprising a reinforcing constituent of fibers embedded in a polymer matrix, wherein the fibers are plant-based fibers, which have been coated with a silicate layer, and wherein the fiber reinforced composition comprises 5 - 98 weight-% of the reinforcing constituent of fibers based on the total weight of the fiber reinforced composition.

The present application further relates to a method for producing a reinforcing constituent of fibers, wherein the method comprises:

- providing at least one plant-based filament fiber;

- treating the at least one filament fiber with a silicate solution for coating the at least one filament fiber with a silicate layer; and

- allowing the at least one coated filament fiber to dry.

The present application further relates to a method for producing a fiber reinforced composition, wherein the method comprises:

- providing at least one plant-based filament fiber;

- treating the at least one filament fiber with a silicate solution for coating the at least one filament fiber with a silicate layer; and

- allowing the at least one coated filament fiber to dry.

The present application further relates to a reinforcing constituent of fibers, wherein the fibers are plant-based fibers, which have been coated with a silicate layer. The present application further relates to a reinforcing constituent of fibers obtainable by the method as defined in the current application .

The present application further relates to fibers, which are plant-based fibers, which have been coated with a silicate layer. The present application further relates to the use of a reinforcing constituent of fibers in a fiber reinforced composite comprising the reinforced constituent of fibers embedded in a polymer matrix, wherein the fibers are plant-based fibers, which have been coated with a silicate layer.

The present application further relates to the use of the fiber reinforced composition as defined in the current application for the production of an aircraft, a boat, an automotive, a bath, a tank, a container, a sport or leisure product such as a surf board, a fishing rod, a ski and golf shaft, or a toy, an electronic or an electrical application such as a printed circuit board or an insulation, a housing of an electronic device, a covering or a casing such as a casing of a laptop or a mouse, a television, a loudspeaker, an audio device, a roofing, a windmill blade, a pipe, a tube, a cable cover, a cladding, a cast, or a door. The fiber reinforced composition may be used in any applications where e.g. traditional fiberglass can be used. In one embodiment, a fiber reinforced composite is used as the fiber reinforced composition .

The inventors surprisingly found out that plant-based fibers that are coated with a silicate layer can be used in a fiber reinforced composition, such as composite, to replace e.g. the commonly used glass fibers. The inventors found out that the formed silicate layer has the added utility of providing the coated fibers with heat resistance needed during the further processing thereof thereby enabling their use for the production of e.g. a fiber reinforce composite .

In one embodiment, the silicate layer comprises or consists of sodium silicate, potassium silicate, or any combination thereof. In one embodiment, the silicate layer comprises or consists of sodium-based alkali silicate, potassium-based alkali silicate, or any combination thereof. In one embodiment, the silicate solution comprises or consists of sodium-based alkali silicate, potassium- based alkali silicate, or any combination thereof.

In one embodiment, the fibers and/or the at least one filament fiber are/is at least partly covered with the silicate layer. In one embodiment, the fibers and/or the at least one filament fiber are/is essentially completely covered with the silicate layer. In one embodiment, at least 50 %, or at least 60 %, or at least 70 %, or at least 80 %, or at least 90 %, or at least 95 %, or at least 98 %, of the outer area of the fibers and/or the at least one filament fiber is covered with the silicate layer. Part of the used silicate solution may be soaked or impregnated into the surface of the fibers and part of it may form a layer on the surface.

In one embodiment, the fiber reinforced composition comprises 5 - 50 weight-%, or 10 - 40 weight-%, or 20 - 30 weight-%, of the reinforcing constituent of fibers based on the total weight of the fiber reinforced composition. When the fiber reinforced composition comprises 5 - 50 weight-%, or 10 - 40 weight-%, or 20 - 30 weight-% of the reinforcing constituent of fibers based on the total weight of the fiber reinforced composition it may be directly used for the production of an end product. It may e.g. be subjected to a formation or molding process to provide the final shape of the end product.

In one embodiment, the fiber reinforced composition comprises 50 - 98 weight-%, or 60 - 95 weight-%, or 70 - 90 weight-% of the reinforcing constituent of fibers based on the total weight of the fiber reinforced composition. When the fiber reinforced composition comprises 50 - 98 weight-%, or 60 - 95 weight-%, or 70 - 90 weight-% of the reinforcing constituent of fibers based on the total weight of the fiber reinforced composition, the manufacturer of the end product, for the production of which the fiber reinforced composition is used, may select a desired further polymer matrix and the adjust the properties of the end product in a desired manner.

The amount of fibers in the fiber reinforced composition can be measured e.g. in the following manner: The sample material is dried in oven in 70 (102) °C for 24 hours. 0.5 1 g of the sample material is weighed into 80 ml of solvent (e.g. dekahydronaphtalene (CioHis) ) and left over night. Then the solution is boiled for several hours (7-8 h) .

After boiling the mixture is filtered out. The material remaining on filter paper is dried in oven in

70 (102) °C for 24 hours and cooled in desiccator. The remaining material is weighed and the fiber amount is calculated .

In one embodiment, the fiber reinforced composition is in the form of at least one granulate, or in the form of a fiber reinforced concentrate, or in the form of a fiber reinforced composite. The at least one granulate or the fiber reinforced concentrate may contain a lesser amount of polymer matrix compared to the amount of polymer matrix present in the fiber reinforced composite.

In one embodiment, the plant-based fibers are selected from a group consisting of natural fibers, man-made fibers, and any combination thereof.

In one embodiment, the plant-based fibers are natural fibers. In this specification, unless otherwise stated, the expression "natural fibers" should be understood as biologically produced fibers. In one embodiment, the natural fibers are obtained from wood, straw, hemp, flax, kenaf, cotton, hemp, or any combination thereof. In one embodiment, the plant-based fibers are plant-based man-made fibers. In one embodiment, the method comprises providing at least one plant- based man-made filament fiber. In this specification, unless otherwise stated, the expression "man-made" fibers should be understood as fibers whose chemical composition, structure, and/or properties are modified by a human being during the manufacturing process thereof. I.e. the one producing the man-made fibers is able to at least partly determine the properties, such as the strength, of the produced fibers. Man-made fibers are to be distinguished from natural, biologically produced fibers. In one embodiment, the plant-based man-made fibers are produced with a spinning apparatus .

In this specification, unless otherwise stated, the expression "plant-based fibers" should be understood as fibers the material of which originates from a plant. In one embodiment, the plant-based fibers are obtained from wood, straw, hemp, flax, kenaf, or any combination thereof. In one embodiment, the plant-based fibers are wood-based fibers, or wood- based cellulose fibers.. In one embodiment, the wood- based fibers are hardwood fibers and/or softwood fibers. In one embodiment, the wood-based fibers are fibers originating from a Kraft process. The Kraft process, which is also known as kraft pulping or sulfate process, is a process for conversion of wood into wood pulp. In one embodiment, the plant-based fibers are fibers of cellulose carbamate, hemicellulose carbamate, or their combination.

In one embodiment, the plant-based fibers have an average fiber length of 0.01 - 60 mm, or 0.1 - 55 mm, or 2 - 50 mm. The length of the plant-based fibers, such as wood-based cellulose fibers, can depend on e.g. wood species, growing conditions, the delignification or pulping process and/or the following beating process that the fibers have been subjected to. In one embodiment, the plant-based fibers are subjected to fractionation, beating, refining, kneading, cutting and/or retting in order to have a desired average fiber length. In this specification, unless otherwise stated, the expression "average length" or "average fiber length" should be understood as the length-weighted average fiber length. In one embodiment, the plant-based fibers have an average fiber width of 10 - 20 ym. The fiber length as well as the fiber width can be determined e.g. according to standard ISO 16065-2:2014 by using a FS5 fiber analyzer or e.g. by using image analysis.

In one embodiment, the ratio of the average fiber length to the average fiber width of the plant- based fibers is above 500, or above 1000.

In one embodiment, the reinforcing constituent of fibers is in the form of a mat or sheet. The fiber mat or fiber sheet may be embedded within the polymer matrix. In one embodiment, the thickness of the fiber mat or fiber sheet is below 2 cm, or below 1 cm, or below 800 ym, or below 300 ym, or below 100 ym. The fibers can be oriented or non- oriented in the mat.

In one embodiment, the fibers are mixed into the polymer matrix. In one embodiment, the fibers are mixed into the polymer matrix to form an isotropic mixture .

In one embodiment, the polymer matrix comprises or consists of a thermoplastic polymer. In one embodiment, the polymer matrix comprises or consists of polyethylene, polypropylene, polyethylene terephthalate, polystyrene, or any other suitable thermoplastic polymer.

In one embodiment, the polymer matrix comprises or consists of a resin, or a thermoset resin, or an epoxy resin. Epoxy resins are low molecular weight pre-polymers or higher molecular weight polymers which normally contain at least two epoxide groups. Epoxy resins are polymeric or semi polymeric materials. Epoxy resins can be produced industrially. The raw materials for epoxy resin production are usually petroleum derived, although plant derived sources are also commercially available, e.g. plant derived glycerol is used to make epichlorhydrin . Difunctional and multifunctional epoxy resins such as diglycidyl ether of bisphenol A (DGEBPA) , triglycidyl p-amino phenol (TGAP) , tetraglycidylether of 4 , 4 ' -diaminodiphenyl methane (TGGDDM) , and epoxy novolacs can be mentioned as examples of epoxy resins that can be used. In one embodiment, the epoxy resin is a hot curing epoxy resin. In one embodiment, the epoxy resin is a cold curing epoxy resin.

In one embodiment, the polymer matrix comprises or consists of bio-monoethylene glycol (bMEG) , bio-monopropylene glycol (bMPG) , or any combination thereof.

In one embodiment, the at least one filament fiber is provided by an extrusion process or by a spinning process. In one embodiment, the extrusion process is a blow extrusion process. In one embodiment, the spinning process is a wet spinning process, a dry spinning process, a dry jet-wet spinning process, a gel spinning process, or a melt spinning process. In one embodiment, the at least one filament fiber is provided by a wet spinning process. The wet spinning process has the added utility of providing a fiber strength that is suitable for many end products.

The form of the filament fiber may vary depending on e.g. its end use. The filament fiber can have any desired or predetermined form or shape. In one embodiment, the filament fiber is hollow or solid. In one embodiment, the cross-section of the filament fiber is essentially circular, quadratic, or has any other predetermined form. The same applies also the staple fiber that may be produced.

In one embodiment the provided at least one filament fiber is pretreated before being treated with a silicate solution to make the surface thereof suitable for the silicate solution treatment.

In one embodiment, the method comprises washing the provided at least one filament fiber at least once before treating the at least one filament fiber with the silicate solution. In one embodiment, the method comprises providing the at least one filament fiber with a wet spinning process and washing the provided at least one filament at least once before treating the at least one filament fiber with the silicate solution. The washing step has the added utility of removing e.g. possible residual alkali present in the filament as a result of its production process. In one embodiment, the washing is carried out with a washing fluid. In one embodiment, the washing fluid is selected from a group consisting of water, an alcohol, and any combination thereof. In one embodiment, the alcohol is selected from a group consisting of methanol, ethanol, and any combination thereof. In one embodiment, the washing fluid comprises auxiliary substances.

In one embodiment, the method comprises treating the provided at least one filament fiber with an acid solution before treating the at least one filament fiber with the silicate solution for regenerating the at least one filament fiber. Treating the provided at least one filament fiber with an acid solution before treating the at least one filament fiber with the silicate solution has the added utility of affecting the otherwise alkaline silicate solution in a manner neutralizing the formed coated filament fiber. In one embodiment, the method comprises treating the provided at least one filament fiber with an acid solution after the at least one filament fiber has been washed but before treating the at least one filament fiber with the silicate solution for regenerating the at least one filament fiber. In one embodiment, the acid solution comprises or consists of sulphuric acid, phosphoric acid, acetic acid, or any other similar kind of acid.

In one embodiment, the method comprises washing the at least one regenerated filament fiber. In one embodiment, the washing is carried out with a washing fluid. In one embodiment, the washing fluid is selected from a group consisting of water, an alcohol, and any combination thereof. In one embodiment, the alcohol is selected from a group consisting of methanol, ethanol, and any combination thereof. In one embodiment, the washing fluid comprises auxiliary substances .

In one embodiment, treating the at least one filament fiber with a silicate solution for coating the at least one filament fiber with a silicate layer comprises embedding the at least one filament fiber into the silicate solution, spraying the silicate solution on the at least one filament fiber, dipping the at least one filament fiber into the silicate solution, and/or transferring the at least one filament fiber through the silicate solution.

In one embodiment, the concentration of the silicate solution varies from a dilute solution to a saturated solution. In one embodiment, the silicate solution comprises or consists of 1 - 80 weight-%, or 3 - 50 weight-%, or 5 - 15 weight-%, of sodium-based alkali silicate, potassium-based alkali silicate, or any combination thereof. The thickness of the formed silicate layer as well as its permanence may be adjusted by adjusting the concentration of the silicate solution .

In one embodiment, the thickness of the silicate layer on the at least one filament fiber is 0.5 nm - 2 mm, or 1 - 500 nm, or 10 - 100 nm.

In one embodiment, the at least one coated filament fiber is rolled for storage and/or further use .

In one embodiment, the at least one coated filament fiber is further treated in a predetermined manner to provide a predetermined form to the reinforcing constituent of fibers. In one embodiment, the at least one coated filament fiber is cut into a predetermined length of staple fiber pieces. In one embodiment, the at least one coated filament fiber is cut into a predetermined length of staple fiber pieces to form the reinforcing constituent of fibers.

The fiber reinforced composition can be produced by any suitable process. In on embodiment, the reinforcing constituent of fibers is mixed or combined with a polymer matrix. The reinforcing constituent of fibers can be mixed or combined with the polymer matrix by using extrusion, molding, lamination, pultrusion, impregnation, a pre-preg process, winding, or any combination thereof.

In one embodiment, the composition formed by mixing or combining the reinforcing constituent of fibers with the polymer matrix is allowed to cure. In one embodiment, the composition formed by mixing or combining the reinforcing constituent of fibers with the polymer matrix is heated, e.g. at a temperature of 20 - 200 °C, or at a temperature of 40 - 180 °C, for curing the composition. In one embodiment, the heating is carried out for 0.5 - 24 hours.

It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages.

The embodiments described hereinbefore may be used in any combination with each other. Several of the embodiments may be combined together to form a further embodiment. A fiber reinforced composition, a reinforcing constituent of fibers, a use, or a method, to which the application is related, may comprise at least one of the embodiments described hereinbefore.

The reinforcing constituent of fibers has the added utility of being based on plant-based fibers, such as wood-based fibers. I.e. most part of the reinforcing constituent of fibers is based on a natural, non-synthetic, material. Thus, the fiber reinforced composition has the added utility of being easier to burn after its use in end products than the fiber reinforced compositions that traditionally use e.g. glass fiber as the reinforcing constituent.

Further, the use of man-made fibers has the added utility of being thermally stable.

The reinforcing constituent of fibers, wherein the fibers have been coated with a silicate layer, has the added utility of outwardly appearing like a glass fiber, i.e. the chemical properties of the provided coating are similar to the ones of glass fiber. This has the added utility of the used polymer matrix experiencing the reinforcing constituent of fibers in a similar manner as it experiences e.g. glass fiber and may thus act in a similar manner as it acts with glass fiber.

The reinforcing constituent of fibers, wherein the fibers have been coated with a silicate layer, has the added utility that a rather thin silicate layer increases the stiffness or rigidity of the plant-based fibers to a rather great extent compared to the stiffness of plant-based fibers that have not been coated with a silicate layer.

Using the reinforcing constituent of fibers, wherein the fibers have been coated with a silicate layer, has the added utility of one being able to adjust the compatibility of the used polymer matrix and the fibers.

The reinforcing constituent of fibers, wherein the fibers have been coated with a silicate layer, has the added utility of behaving in a similar manner as glass fiber whereby it may be used in a similar manner and with similar kind of processes as glass fiber.

EXAMPLES

Reference will now be made in detail to the described embodiments.

The description below discloses some embodiments in such a detail that a person skilled in the art is able to utilize the reinforcing constituent of fibers, the fiber reinforced composition, the fibers, and the method based on the disclosure. Not all steps of the embodiments are discussed in detail, as many of the steps will be obvious for the person skilled in the art based on this specification.

EXAMPLE 1 - Producing a fiber reinforced composition

In this example a fiber reinforced composition was prepared. The following components were used:

Sodium-based alkali silicate solution (10 % v/v) Polymer matrix (epoxy resin)

Wood-based cellulose fibers (softwood fibers) Firstly, wood-based cellulose filament fibers were provided by a wet spinning process. The provided wood-based cellulose filament fibers were then washed with water and treated with a 10 % (v/v) sulphuric acid solution for regenerating the filament fibers. After having treated the filament fibers with the sulphuric acid solution, the filament fibers were again washed with water.

After the above steps the wood-based cellulose filament fibers were treated with a sodium- based alkali silicate solution by immersing the filament fibers in the sodium-based alkali silicate solution such that a sodium silicate layer was formed on the filament fibers. After treating the filament fibers with the sodium-based alkali silicate solution, the filament fibers were allowed to dry in room temperature for 5 hours.

The coated filament fibers were then cut into staple fiber pieces having an average fiber length of about 2 mm (as measured with a Kajaani Fiberlab FS200 device) . The fibers were then mixed into the epoxy resin for embedding said fibers therein by the use of a molding process. Then the formed mixture was heated at a temperature of 125 °C for 18 hours for curing the composition .

From tests performed on the produced fiber reinforced composition, it was noted that produced fiber reinforced composition had properties such as strength suitable for use in further applications.

It is obvious to a person skilled in the art that with the advancement of technology, the basic idea may be implemented in various ways. The embodiments are thus not limited to the examples described above; instead they may vary within the scope of the claims. The embodiments described hereinbefore may be used in any combination with each other. Several of the embodiments may be combined together to form a further embodiment. A composition, a method, a reinforcing constituent of fibers, fiber, or a use, disclosed herein, may comprise at least one of the embodiments described hereinbefore. It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. It will further be understood that reference to 'an' item refers to one or more of those items. The term "comprising" is used in this specification to mean including the feature (s) or act(s) followed thereafter, without excluding the presence of one or more additional features or acts.