WO2015193534A1

WO2015193534A1 - A method to provide composite comprising a desiccating process agent and composites thereof

Info

Publication number: WO2015193534A1
Application number: PCT/FI2014/050487
Authority: WO
Inventors: Harri Kosonen; Sami Turunen; Jere SALMINEN; Petri MYLLYTIE; Kari Luukko; Stefan Fors
Original assignee: Upm-Kymmene Corporation
Priority date: 2014-06-18
Filing date: 2014-06-18
Publication date: 2015-12-23

Abstract

The invention relates to a method for obtaining a composite comprising organic natural fiber material, in particular to a composite comprising chemically treated organic material, and to products thereof. The method comprises providing a composition mixture comprising organic natural fiber material and thermoplastic polymer material, providing a composition melt by melting the composition mixture, introducing a desiccating process agent having a moisture binding capacity, and forming a composite comprising the organic natural fiber material, the thermoplastic polymer material and the desiccating process agent.

Description

A method to provide composite comprising a desiccating process agent and composites thereof

Field of invention

The invention relates to manufacturing a composite comprising chemically treated organic natural fiber material with desiccating process agent and to a composite thereof. Background

Polymer composites comprising organic natural fiber material may be used to manufacture products for various industrial applications. In many environments, it may be useful for the composite to have specific properties. In some applications it may even be necessary that the composite meets the quality levels set for the application to function. Composites may typically comprise organic natural fiber material and at least one kind of plastic polymer. Additionally, other compounds may be used in a composite to improve the material properties. Such composites may be manufactured for several purposes, both indoors and outdoors.

Summary

Composites comprising chemically treated organic natural fiber material and polymer matrix may be used in an increasing amount of applications globally. Different applications may require specific properties from the composite. For example, a composite may be used in outdoor environments, where they may be exposed to temperature and humidity variations. Indoor applications of a composite may require a specific surface property, such as transparency, gloss or a smoothness level. An application may require thin composite material, such as in a form of a sheet or a film. An application may involve shaping of the composite material to different purposes, for example by pressing and/or thermoforming the material into products having curvature regions, such as used for packaging material or panels, to name a few examples. In some applications, the thickness of the composite may vary along the composite length or width, to provide regions having less mechanical strength, for example when splitting a single composite product into two or more defined and separate parts. To obtain specific properties for a composite, the composition of the composite material may be controlled. Furthermore, the manufacturing process may be modified to obtain specific properties for the composite.

When processing composite material comprising organic natural fiber material, the material may comprise strength, stiffness and sufficient strain at break for controlled processability. In particular, when processing composite material comprising organic natural fiber material, the process conditions may comprise temperature ranges defined according to the selected composition and shorter manufacturing times to reduce the heat stress for the material. When forming an extruded or moulded thin composite, such as a sheet or planar (plate-like) product, the composition and characteristics of the composite melt may have an effect on further processing of such a composite. Such composite may be further processed to change the shape of the product, for example by means of heating and pressing.

The use of chemically treated organic natural fiber material has special characteristics when forming a composite. Adding fiber material in the form of chemically treated pulp may be used to select desired melt properties for the composite melt. The fiber material in the form of chemically treated pulp may improve the processability of the composite melt. By controlling the amount and/or properties of the fiber material, such as chemical pulp, the manufacturing process may therefore be modified obtain desired properties for the composite melt. When chemically treated organic natural fiber material is obtained, other compounds naturally present in an organic natural fiber material may be separated. Chemical pulp such as Kraft pulp has been bleached. The lignin content of the chemically treated organic natural fiber material has been reduced. Other components such as acidic components or other low molecular weight extractives such as fatty acids, resin acids, waxes and terpenes naturally occurring in wood material may have been reduced. The visual appearance of chemical pulp material is a factor having an effect on the use of a composite and in a product comprising the composite. Fiber material in the form of chemically treated pulp may be provided having a defined average fiber length and fiber length distribution, which have an effect to the reinforcement capability of the fiber material in the composite product. The composition, behaviour and properties of the chemically treated organic natural fiber material may therefore be more specific and controlled to a greater extent, than that of organic natural fiber material obtained by other method, such as conventional wood flour or saw dust, to name some examples.

One problem in a method to obtain a composite comprising chemically treated organic natural fiber material is the moisture content level. As the chemical treatment removes naturally hydrophobic compounds from the organic natural fiber material, a chemically treated organic natural fiber material tends to absorb and retain moisture. Water may be present in the fiber material in different forms. Before forming a composite, the moisture content of the fiber material may be diminished, for example by evaporation. Heating may be used to evaporate non-bound water referred to as 'free water' from the organic natural fiber material and/or the composition melt during processing. Heating above a temperature of 100°C, for example at a temperature of 105°C reduces the moisture content. However, some residual water may still remain in the fiber material. In particular, water molecules bound through hydrogen bonding may still be present in the chemically treated organic natural fiber material. To reduce the moisture content of the chemically treated organic natural fiber material for improved processability, heating at a higher temperature, such as in the range of 140°C to 220°C, may be used.

When heating a composition melt containing chemically treated organic natural fiber material under pressure, such as on an extruder screw, the used temperature and pressure typically are sufficient for cleaving the hydrogen bonding of water molecules bound through hydrogen bonding, and at least some of the residual water may be released into a non-bound state, which moisture remains in a liquid state in the composition melt. When forming a composite, a diminishing pressure combined to a temperature above the evaporation temperature of water may result in a rapid evaporation of the liquid into a gaseous state. This phase change of the residual water may lead to expansion of gaseous material inside and/or on the surface of the composite, and may cause detrimental effects on the composite, such as surface irregularities or porosity. These detrimental effects may have a further effect on the material properties, for example on the flexural or tension properties of the material. The effects of moisture are especially detrimental when using chemically treated organic fiber material; other types of fiber materials may not be as sensitive to moisture as chemically treated organic fiber material.

The formed composite may be an intermediate product suitable for further manufacturing processes, such as an extruded pellet, or a shaped composite product, for example an extruded sheet or a moulded profile. When the intermediate product comprises cavities, such as closures or voids inside the material comprising gaseous material, it may have an effect on a further process where the intermediate product is used. Means of providing shaped composite and composite products include extrusion methods and moulding methods. In some methods, the presence of gaseous material, such as air, may cause problems. For example, when a system is not equipped for removal of excess gaseous material or vapour, the gaseous material present in a composition melt may be trapped and lead to shape irregularities or undesired porosity in the formed composite product. The gaseous material may further promote combustive reactions, for example in pressurized chambers such as used in injection moulding this may lead to reactions causing surface irregularities or colour defects on the surface. In particular, methods such as sheet extrusion and thermoforming using composite comprising organic natural fiber material may be especially sensitive to the presence of moisture in the composite during manufacturing.

Desiccating process agent is material which is sensitive to moisture. Addition of a desiccating process agent may be used to reduce the effects of moisture when forming a composite. In particular, when forming a composite, a desiccating process agent having a moisture binding capacity may be used. A desiccating process agent may further provide means to improve the processability of a composite melt, for example by changing the density of the material and/or by providing melt strength. Some desiccating process agents, such as mineral oxides, may react with other compounds. A desiccating process agent forming a chemical reaction may provide functionality to the composite. For example, a mineral oxide such as calcium oxide forms a chemical reaction with water. A desiccating process agent may thus have an effect on the pH level of the composite. Alkaline pH levels caused by a desiccating process agent such as calcium oxide may lead to unwanted colouring (yellowing) of the cellulose fibers and change the appearance and/or other mechanical properties of the composite. Providing means to reduce the amount of desiccating process agent in a composite are thus desirable. Late addition of a desiccating process agent improves the effect of the desiccating agent and provides means to reduce the amounts added. Heating the composition melt may further be used to reduce the fiber moisture content before introducing the desiccating process agent.

Objects and embodiments of the invention are further described in the independent and dependent claims of the application. Description of the Drawings

Figures 1 a and 1 b illustrate, by way of an example, organic natural fiber

FIB1 material. Figure 2 illustrates, by way of an example, a length measurement of organic natural fiber material from a composite surface.

Figure 3 illustrates, by way of an example, a method for obtaining a composite.

Figure 4 illustrates, by way of an example, another method for obtaining a composite.

Figure 5 illustrates, by way of an example, a method for obtaining a composite by extrusion. Figures 6 illustrates, by way of an example, a method for obtaining an intermediate product by extrusion. Figure 7 illustrates, by way of an example, process parameters and parameter values as a function of time in a method for obtaining a composite. Figures 8 illustrate, by way of examples, obtaining composite products by thermoforming.

In the figures, S_x, S_y and S_z are orthogonal directions perpendicular to each other.

Detailed Description

A composite refers to a formed material, which comprises two or more material components combined together, wherein the constituents can retain their identity. At least one of the main components is organic natural fiber material and another of the main components is a matrix material, preferably a thermoplastic polymer material. Other processing agents, such as desiccating process agents, coupling agents, lubricants, colorants, ultra-violet degradation inhibitors, anti-fungicidal components or anti-microbial components may be blended into the composite during the manufacturing process. The main components of a composite may not dissolve or otherwise merge completely with each other. The properties of the composite may differ from the properties of the main components acting alone. Mechanical properties of a composite depend on many aspects. For example, when the composite comprises fiber material and polymer matrix, the fiber material type, fiber material properties, fiber material content, fiber material length, dispersion, and adhesion between the fiber material and matrix material as well as moisture content may have an effect on the manufacturing process and on the mechanical properties of the composite. For example, the stiffness of the composite may increase when fiber material is added to the matrix material. A composite product is a product comprising the composite. A composite product may be formed of the composite. A composite product may be formed, for example, by means of extrusion, moulding or thermoforming. A composition mixture refers to ingredients mixed together for obtaining a composite. A composition mixture may comprise organic natural fiber material and thermoplastic polymer material. Providing a composition mixture comprises mixing the ingredients, such as organic natural fiber material and thermoplastic polymer material. Further, when providing the composition mixture, a desiccating process agent having a moisture binding capacity may be introduced. The ingredients may be provided to the manufacturing process as a pre-mixed master batch, or as separate raw material components, depending of the nature of the ingredients. The thermoplastic polymer material used for mixing may be introduced in a solid form, for example as powder, granules or pellets. The chemically treated organic natural fiber material is typically provided in a solid form, for example as large fiber or fiber bundles, pulp chaff or as crushed pulp material. The ingredients may also be provided as a preliminary mixture comprising organic natural fiber material and thermoplastic polymer material. A preliminary mixture refers to a composition mixture, which is used in forming a preliminary composition melt. A preliminary composition melt is used in forming a preliminary composite product. A composition melt refers to a composition mixture, which comprises chemically treated organic natural fiber material and thermoplastic polymer material, and which composition mixture has been heated in order to melt the thermoplastic polymer material. The temperature of the composition melt is equal to or higher than the melting point T_m and/or the glass transition point T_g of the thermoplastic polymer material, where the thermoplastic polymer material begins to melt. A composite melt may have a flow with direction, denoted as a direction of the melt flow DIRMD- When processed to a composite, composition melt may be introduced in the direction of the melt flow DIRMD- Further, when providing the composition melt, a desiccating process agent having a moisture binding capacity may be introduced.

A preliminary composite product refers to an intermediate product, which may be further used to obtain composite or a composite product. A preliminary composite product may be a spherical, cylindrical or granular intermediate product. A composition mixture may, for example be provided by introducing preliminary composite product into a method for obtaining a composite. An intermediate composite product therefore refers to an object suitable for further processing, such as material usable for a composition melt. To improve handling, a preliminary composite product may have a suitable volume for further manufacturing processes, such as a volume of less than 2 cm³.

A thermoplastic polymer material refers to matrix material, which is used when providing a composition mixture or a preliminary mixture. A thermoplastic polymer material may be mixed with organic natural fiber material, in particular with chemically treated organic natural fiber material. Organic natural fiber material is typically compounded with a matrix material. When using a composition melt for forming a composite, a thermoplastic polymer material consisting of one or more thermoplastic polymers may be used. A thermoplastic polymer in general is solid at low temperatures and forms a viscose polymer melt at elevated temperatures. A thermoplastic polymer material may be a polyolefin, such as a C2 to C4 polyolefin. Some examples of thermoplastic polymer materials suitable for a composite are polyethylene, polypropylene, polystyrene, ABS and PVC. A desiccating process agent refers to material which has a moisture binding capacity in a method for obtaining a composite. A desiccating process agent is capable of physically or chemically binding water. When added, the desiccating process agent reacts with water or binds water under the melt processing conditions. A desiccating process agent may also be referred to as a drying agent. A desiccating process agent may be introduced as such, or as a pre-mixed master batch.

Moisture content refers to water present in organic natural fiber material, or to water present in a composite comprising organic natural fiber material. When the composite comprises a thermoplastic polymer such as described above, most of the moisture content is of the water present in organic natural fiber material . Polypropylene and polyethylene in particular do not absorb moisture, and contain mostly surface moisture. In contrast, chemically treated organic natural material, such as chemical wood based pulp, may absorb significant amounts of moisture. The fiber moisture content w_Fi , refers to water present in organic natural fiber material when providing a composition mixture. The fiber moisture content w_Fi of organic natural fiber material, and of chemically treated organic natural fiber material in particular, contains both water present as free water (non-bound moisture) and as residual water (attached to the fiber material through hydrogen bonding). The fiber moisture content w_Fi may be reduced by means of drying the organic natural fiber material, such as evaporation by heating. A desiccating process agent may further be used to reduce the fiber moisture content w_Fi by binding the residual water to at least some extent. Use of a desiccating process agent may reduce the fiber moisture content w_Fi to a lower level referred as moisture content w_F2 or further to a moisture content w_F3. The moisture content w_F3 represents the moisture content of a composite.

A chemically treated organic natural fiber material refers to organic natural fiber material, which has been treated chemically. A chemically treated organic natural fiber material typically consists essentially of cellulose obtained from chemically treated pulp of wood origin. Minor amounts of other compounds may be present in the chemically treated organic natural fiber material. The chemically treated pulp may be, for example, from kraft process or sulfite process, but also other chemical processes may be used. Preferably, the chemically treated organic natural fiber material is from the kraft process, which is widely used and provides organic natural fiber material having homogenous properties.

Organic natural fiber material in a composite may be used to replace, at least in part, other materials, such as polymer matrix. Therefore, composite material comprising organic natural fiber material and the manufacture of such material may be deemed as an effort to promote environmentally friendly technology and sustainable development, comprising renewable material .

Composite comprising organic natural fiber material may be used as a substitute for plastic or wooden products on many applications both outdoors and indoors, a non-limited exemplary listing including decking boards, construction materials, decorative items, frames, panels, facades, flooring, fencing, decking, stairs, rails, window frames, trims, pallets, containers, household articles, automotive parts, vehicle accessories, consumer spare parts, handles and the like. Furthermore, composite may be used in the packaging industry. Thin composite may be used for example as sheets or films to support or cover substances or other products. In particular, a composite having a food contact substance approval may be used for materials in contact with food. A composite may be used for medical purposes, for example as packaging material for medical devices or medicines, or as a surface material.

A method to obtain composite may comprise a moulding process, to obtain moulded products. In particular, a moulded product made of composite comprising organic natural fiber material may comprise, for example, an injection moulded product, an extruded product, a thermoformed product, a compression moulded product or a rotation moulded product. A method to obtain composite may comprise an extrusion process, to obtain profiles or sheets. Depending of the shape of the article, the method may be selected to obtain a desired shape. A composite may have a shape suitable for a specific application, such as a moulded product, profile or sheet. A method to obtain composite may comprise forming a preliminary composite product. The selected method of manufacturing may depend of the desired shape or characteristics of the composite to be obtained. The manufacturing method may further comprise a combination of any of the methods. For example, a composite product may be obtained by a extrusion method, and be further processed into another shape by thermoforming.

Chemically treated organic natural fiber material

Organic natural fiber material refers to material that contains cellulose. Organic natural fiber material further refers to material such as fibers or fiberlike particles that contain cellulose. Organic natural fiber material may be divided into wood originating and non-wood originating material. Non-wood material is typically present in agricultural residues, such as grasses or other plant substances such as straw, coconut, leaves, bark, seeds, hulls, flowers, vegetables or fruits from cotton, corn, wheat, oat, rye, barley, rice, flax, hemp, manila hemp, sisal hemp, jute, ramie, kenaf, bagasse, bamboo, or reed. The wood material can be softwood trees, such as spruce, pine, fir, larch, douglas-fir or hemlock, or hardwood trees, such as birch, aspen, poplar, alder, eucalyptus, or acacia, or a mixture of softwoods and hardwoods. The organic natural fiber material may comprise recycled material, for example raw material pulp of recycle streams of wood materials. The recycled material may comprise recycled paper material. The organic natural fiber material may be, at least partly, in the form of large fiber or fiber bundles, paper chaff, pulp chaff, crushed pulp material, derivatives thereof and their combinations.

While cellulose is present in non-wood material, such as in agricultural residues, cellulose fibers originating from wood material is preferred. Pulp and paper industries provide large amounts of organic natural fiber material in a cost efficient manner. In particular, many operations in the kraft process have a positive energy balance and can be used provide heat or electricity to other operations.

Organic natural fiber material may be mechanically treated. Mechanically treated refers to organic natural fiber material, which is isolated from organic natural raw material comprising cellulose by a mechanical pulping process. The mechanical pulping process could be preceded by a chemical pretreatment, producing chemimechanical pulp. The mechanically treated organic natural fiber material may be, for example, ground, refined and/or powdered from the source used. In other words, a mechanical force has been used to treat the source of the organic natural fiber material. The mechanically treated organic natural fiber material may comprise, among other things, wood flour, saw dust, chip material, and/or mechanical pulp such as thermo mechanical pulp (TMP), groundwood pulp (GW), stone groundwood pulp (SGW), pressure groundwood pulp (PGW), refiner mechanical pulp (RMP), and/or chemithermomechanical pulp (CTMP). The mechanically treated organic natural fiber material typically comprises or consists of wood-based material, such as wood-based fibers, but may also comprise or consist of non-wood material. Mechanically treated organic natural fiber material typically comprises lignin. In mechanically treated organic natural fiber material, such as cellulose based fiber material, lignin is present in various amounts, but typically in higher amounts than in chemically treated organic natural fiber material. Lignin is a highly polymeric material, able to crosslink and may act as a water repellent in a cellulose based fiber plastic composite. For example in wood cells the presence of lignin limits the penetration of water into the wood cells, which makes the structure very compact. Organic natural fiber material comprising lignin, however, is prone to decompose more easily at relatively low extrusion or injection molding temperatures, for example in the range of 100^°C to 150^°C, than fiber material free of lignin. Furthermore, the presence of lignin in a composite product may lead to a product comprising odours or other side effects, such as colour defects like yellowing. Depending of the end use, the presence of odours or other side effects in a product may be undesired.

Organic natural fiber material may be chemically treated. Chemically treated organic natural fiber material comprises chemical wood based pulp. Chemically treated organic natural fiber material consisting essentially of cellulose may be obtained from chemically treated pulp of wood origin. Minor amounts of other compounds may be present in the chemically treated organic natural fiber material. The chemically treated pulp may be, for example, from kraft process or sulfite process, but also other chemical processes may be used, such as a soda pulping process. Preferably, the chemical pulp is from the kraft process, which is widely used and provides organic natural fiber material having homogenous properties.

Advantageously, at least 30 wt.% or at least 40 wt.%, more preferably at least 50 wt.% or at least 60 wt.%, and most preferably at least 80 wt.% or at least 90 wt.% of the organic natural fiber material is chemically treated. According to an example 100 wt.% of the organic natural fiber material is chemically treated. Advantageously, at least 30 wt.% or at least 40 wt.%, more preferably at least 50 wt.% or at least 60 wt.%, and most preferably at least 80 wt.% or at least 90 wt.%, or at least 95 wt.% of the chemically treated organic natural fiber material originates from a kraft process. Advantageously, the pulp production method for organic natural fiber material comprising cellulose is based on sulfate cooking, also called as kraft cooking or pulping. Advantageously, lignin content of the chemically treated pulp is below 10 wt.%, preferably below 5 wt.% or 3 wt.%, more preferably below 2 wt.% or 1 wt.%, such as in the range of. 0.01 -10 wt.%, preferably 0.01 -5 wt.%, more preferably 0.01 -3 wt.%, 0.01 -2 wt.% or 0.01 -1 wt.% and most preferably 0.01 -0.5 wt.%. Preferably, the alfa cellulose content of the chemically treated pulp is above 50 wt.%, preferably above 60 wt.%, more preferably above 70 wt.% and most preferably above 72 wt.% or above 75 wt.%. Advantageously, the alfa cellulose content of the chemically treated pulp is below 99 wt.%, preferable below 90 wt.%, more preferably below 85 wt.% and most preferably below 80 wt.%.

The amount of the organic natural fiber material is calculated as the total amount of the organic natural fiber material in a system, composite or a composite product.

Different types of organic natural fiber materials may be used in a method to obtain composite. Mechanically treated organic natural fiber material comprising lignin may be used in a method to obtain composite. Chemically treated organic natural fiber material may be used in a method to obtain composite. Chemically treated organic natural fiber material has many beneficial characteristics. When providing organic natural fiber material in the form of chemically treated pulp, the structure of the organic natural fiber material is changed. Therefore, the properties of organic natural fiber material in the form of chemically treated pulp may differ from other types of organic natural fiber materials. Chemically treated organic natural fiber material is essentially odourless. Chemically treated organic natural fiber material is bleached. A bleached fiber may be a visual factor appearing in the end product, which may be desirable. In particular, due to the obtainable homogeneous properties, the characteristics of chemically treated organic natural fiber material are easy to control. For example, the particle size of chemically treated organic natural fiber material typically comprises a narrow length distribution, which together with the homogeneous composition may be used to provide composite with selected properties. Therefore, chemically treated organic natural fiber material is easy process. The chemically treated organic natural fiber material may comprise chemically treated fibers and/or fiber-like particles. The density of untreated or mechanically treated organic natural fiber material such as wood is variable, whereas chemically treated organic natural fiber material in general has an essentially homogeneous properties, such as composition and structure. Chemically treated organic natural fiber material is characterised by having reduced amount of compounds with adverse effects, which compounds are typically present in other organic natural fiber material types of wood origin. Examples of such compounds are lignin, acidic components and hemicellulose. Chemical treatment of the organic natural fiber may be used to remove lignin, hemicellulose and low molecular weight extractives from the cellulose fibers at least to some extent. However, when reducing organic compounds from the cellular structure by chemical treatment, also the behaviour of the fiber material is changed. Lignin is a naturally hydrophobic compound, naturally present in wood and in many mechanically treated organic fiber materials obtained from wood. For example, wood based material such as wood flour, chips or saw dust may repel water to some extent due to their cellular structure. Lignin is resistant to moisture and thus has an effect on the absorbance capability of the organic natural fiber material. Chemically treated organic natural fiber material has a reduced lignin content, and may be essentially lignin free. This may have an effect on the residual water content and moisture absorbance behavior of the organic natural fiber material. The chemical treatment exposes the micro-fibrils of cellulose to environmental conditions. At the same time, the lignin content is reduced to at least some extent, and the hydrophobic part of the fiber material is lost. Chemically treated organic natural fiber material is moisture absorbing, in particular when compared to other types of organic natural fibers comprising lignin. Typically, the cellulose content of a chemically treated organic natural fiber material is high, and the chemically treated organic natural fiber material comprises a high amount of hydroxyl groups present in the cellulose available for hydrogen bonding. A chemically treated organic natural fiber material has an increased surface area compared to organic natural fiber material obtained by many other methods, such as conventional wood flour or saw dust. The increased surface area introduces non-bound hydroxyl groups available for hydrogen bonding in the surface chains of the cellulose molecules, which promotes forming of hydrogen bonds to water. Water molecules are in general present as moisture in the air, and readily form hydrogen bonds with the hydroxyl groups of the cellulose molecules.

Particle size and dimensions

A chemically treated organic natural fiber material consists of particles. The particles may be in the form of fibers. Particles having a length of at least 0.05 mm, more preferably at least 0.1 mm and most preferably at least 0.3 mm may be called fibers. The fibers may be may be floccules, single fibers, or parts of single fibers. Particles having a length of less than 0.05 mm may be called powder or fiber-like particles. Fiber-like particles may comprise material, which does not have an exactly spherical form. Preferably the organic natural fiber material is, at least partly, in the form of fibers. At least 40 wt.% or at least 50 wt.%, more preferably at least 60 wt.% or at least 70 wt.% and most preferably at least 80 wt.% of the organic natural fiber material may be in the form of fibers. According to an example, 100 wt.% of the chemically treated organic natural fiber material is in the form of fibers, such as cellulose microfibrils. Preferably at least 70%, at least 80 % or at least 90 % of the chemically treated organic natural fiber material has a length weighted fiber length of under 4 mm, under 3 mm or under 2.5 mm, more preferably under 2.0 mm, under 1 .5 mm, under 1 .0 mm or under 0.5 mm. Preferably, at least 70 wt.%, at least 80 wt.%, or at least 90 wt.% of the chemically treated organic natural fiber material has a length weighted fiber length of at least 0.1 mm or at least 0.2 mm, more preferably at least 0.3 mm or at least 0.4 mm. Advantageously, the fiber has a shape ratio relating to the ratio of the fiber length to the fiber thickness being at least 5, preferably at least 10, more preferably at least 25 and most preferably at least 40. In addition or alternatively, the fiber has a shape ratio relating to the ratio of the fiber length to the fiber thickness being preferably 1500 at the most, more preferably 1000 at the most, and most preferably 500 at the most. High shape ratio relates to reinforcing component with higher stiffness and impact strength for the same chemically treated organic natural fiber material content. This can be described by modulus, for example Young's modulus or elastic modulus, which is a measure of the stiffness of a material and may be used to characterize materials. The chemically treated organic natural fiber material may form reinforcing components in the structure.

Fiber shape and dimensions

A composite may comprise chemically treated organic natural fiber material in a flake form having a length, a width and a thickness. A flake is a particle having a defined shape. The width of the flake may be at least 2, or preferably at least 2.5, or more preferably at least 3 times the thickness of the flake. The width of the flake may be 2-10 times larger than the thickness of the flake. The flake form may have an aspect ratio relating to the ratio of the length to the thickness of 25-1500, or preferably 25-1000, or more preferably 25-500, or most preferably 25- 300. Figures 1 a and 1 b illustrate, by way of examples, of chemically treated organic natural fiber material FIB1 . The flake FLK1 of Figure 1 a has a width W0 and a thickness HO, wherein the width is larger than the thickness. The flake FLK1 of Figure 1 a has a length L0, which may be its widest dimension. The width W0 and thickness HO may illustrate a cross section dimensions of the face of the flake FLK1 . The face may be shaped oval-like or rectangular- like, as illustrated in Figure 1 b, or the face of the flake FLK1 may have a random shape. A random shape of the flake FLK1 may continue along the flake FLK1 length L0. According to an embodiment cellulose fibers in the microstructure of a flake FLK1 have been oriented along the length L0 direction of the flake FLK1 . Flakes may have a width W0 that is 2-10 times larger than the thickness of the fibers. Advantageously, the width of the flake FLK1 W0 is at least 2, preferably at least 2.5, and more preferable at least 3 times the thickness HO of the flake FLK1 . Preferably, the flakes have a thickness HO between 1 and 30 micrometers (μιτι) and more preferably the thickness HO of flakes varies from 2 to 20 micrometers (Mm). Most preferably the thickness HO of flakes is 2-15 μιτι, more preferably 2-10 μιτι and most preferably 2-7 μιτι. According to an embodiment, the width W0 of the flake FLK1 is 20-500 μηη, preferably 20-200 μηη, and more preferably 20-50 μηη. Preferably, an aspect ratio relating to the ratio of the length L0 to the width W0 is between 10 and 100. Preferably, an aspect ratio relating to the ratio of the length L0 to the thickness HO is 25-1500 or 25-1000, more preferably 25- 500 and most preferably between 25 and 300. According to an embodiment, the length L0 of the flake FLK1 is at least 10 times the width W0 of the flake FLK1 . According to an embodiment the flake FLK1 has a tubular shape. According to an embodiment the flake FLK1 has a platy shape. According to an embodiment, the chemically treated organic natural fiber material FIB1 comprises flake FLK1 form fiber material at least 30 dry wt.%, preferably at least 50 dry wt.%, or more preferably at least 70 dry wt.%, or most preferably at least 80 dry wt.% of the total amount of the chemically treated organic natural fiber material FIB1 . According to an example the chemically treated organic natural fiber material FIB1 contains flake-form fiber material at least 98 dry wt.%, or 100 dry wt.% of the total amount of the chemically treated organic natural fiber material FIB1 .

Fiber quantity in a composite

The dry weight of chemically treated organic natural fiber material in a composite may be denoted as m_org. The weight of the composite may be denoted as m_tot. The amount of organic natural fiber material in the composite may be expressed as a ratio m_org / m_tot-

According to an embodiment m_org may be at least 5 wt.% or at least 10 wt.% or at least 20 wt.% of m_tot, advantageously at least 30 wt.% or at least 35 wt.% or at least at least 40 wt.% or at least 50 wt.% of m_tot, or at least 60 wt.% or at least 70 wt.% or at least 80 wt.% or up to 90 wt.% of m_tot-

The ratio m_org / m_tot may be in the range of 0.05 to 0.9, e.g. in the range of 0.1 to 0.8 or in the range of 0.15 to 0.7, for example between 0.2 and 0.6 or 0.2 and 0.5. The ratio m_org / m_tot may be selected based on the desired properties of the composite. In particular, by selecting the m_org / m_tot ratio, the behavior of the mixture may be controlled when manufacturing the composite. According to an embodiment the ratio m_org / m_tot may be in the range of 0.05 to 0.5 or between 0.1 to 0.4. Fiber length and length distribution of chemically treated pulp

When providing chemically treated organic natural fiber material having a specific average length and average length distribution, specific properties may be obtained on a composite. For example, composites with same composition but different average fiber length may comprise different melt flow index and viscosity. When providing reinforcing functionality, a higher average fiber length may be preferred. For improved melt flow properties, a lower average fiber length in the organic natural fiber material may be preferred. Chemically treated organic natural fiber material may be produced in different average fiber lengths. By providing sufficient shear stress, the length of the fibers may be reduced. For example cutters or mills may be used as means to provide shear stress. As an example, screening technologies based on sieves, gravity or sedimentation may be used to obtain selected fractions of a length distribution.

Measuring fiber length Fiber length is the longest dimension of a particle such as fiber or a flake having a length, a width and a thickness, and may be measured using various techniques, such as electrozone sensing (Coulter counter), optical means, laser diffraction or microscopy image analysis, to name a few. Fiber length of a curved, twisted or bended fiber is the linear dimension of the fiber in a non-curved state. In other words, the length of a fiber or a flake is the longest dimension the particle would have, when it would be straight. The fiber length may be measured either from chemically treated organic natural fiber material before mixing to a composition melt, or from a formed composite.

In an example, the average fiber length may be measured from a group of individual fibers. The individual fibers may be sampled from chemically treated organic natural fiber material. The individual fibers may be sampled before addition of the chemically treated organic natural fiber material to a mixture. The individual fibers may be sampled before heating the fiber material at 105°C, to evaporate non-bound moisture. The group of fibers may comprise at least 100 fibers. The group of fibers may comprise multiple samples, such as at least 2, 3, 4, 5 or more different samples from the fiber material . Use of multiple samples enables representative measurement of the average fiber length and fiber length distribution in the fiber material.

An electrozone sensing, such as a Coulter counter, may be used to measure the lengths of the fibers. The fiber material measured by electrozone sensing is material to be added on a mixture. In electrozone sensing the sample to be analysed, for example fiber material, is prepared as a suspension in a dilute electrolyte. By providing a group of fibers in a liquid suspension, the number average length of the group of fibers representing the fiber material may be determined. When using electrozone sensing, a sample of fiber material comprising a group of at least 100 fibers may be used. A method using light polarizing optics may also be used for determining numerical and weighted average fiber lengths and fiber length distributions. For example, the fiber length may be measured according to TAPPI/ANSI T271 om-12. An example of fiber length measurement device according to the TAPPI standard method T271 is the FiberLab image analysis tool.

Definition of average length and length distribution

An average length and a length distribution may be measured for a group of fibers. A number average fiber length L_N, a length average fiber length L_L or a fiber length index FLI may be used to describe the fiber length properties. The number average fiber length is a statistical average of fiber lengths of fibers in the sample according to equation 1 below:

Equation 1 : L_N = (ΣΝ,Ι_ί)/∑N,

, where L, is a length of a fiber and N, is the number of fibers having length L,. The length average fiber length is defined by equation 2 below: Equation 2: L_L = (∑Nil_i²)/∑N,Li

, where L, is the length of a fiber and N, is the number of fibers having length Li.

High number average fiber length L_N may be used to improve mechanical properties, such as high tensile strength, high tensile modulus, and high notched and unnotched impact strength. Low number average fiber length L_N enable better flowing properties of the composite comprising organic natural fiber of chemically treated pulp. Low number average fiber length L_N also enables easier and longer extension of the composite material in the composition melt. These properties are particularly beneficial in thermoforming, where the composite typically is stretched and shaped to obtain concave formations. A low number average fiber length L_N provides lower viscosity, higher melt flow index MFI and improved moldability during thermoforming.

Fiber length index FLI value refers to the ratio L_L/L_N between the length average fiber length and the number average fiber length. A narrow fiber length index FLI value provides reinforcing functionality, whereas a wide fiber length index FLI value provides improved melt flow properties.

Fiber length distribution of chemically treated organic natural fiber material is narrow, when the fiber length index FLI value is less than 1 .5, such as in the range of 0.9 to 1 .49, more preferably is in the range of 0.95 to 1 .3 and most preferably is in the range of 1 .0 to 1 .2. Fiber length distribution of chemically treated organic natural fiber material in this document is wide, when the fiber length index FLI value is equal to or more than 1 .5, such as in the range of 1 .5 to 40, more preferably in the range of 1 .5 to 20 and most preferably in the range of 1 .5 to 10, for example in the range of 1 .5 to 3, more preferably in the range of 2 to 5 and most preferably in the range of 2 to 2.3.

Each organic natural fiber material has an intrinsic fiber length distribution. When using a chemically treated organic natural fiber material, a narrow fiber length distribution may be obtained by means of milling or grinding. When a wider fiber length distribution is desired, two or more types of chemically treated organic natural fiber material having different intrinsic fiber length distributions may be mixed to obtain a desired width for the fiber length distribution.

According to an embodiment number average fiber length L_N of chemically treated organic natural fiber material may be in the range of 0.05 to 0.5 mm and the fiber length distribution of chemically treated organic natural fiber material is narrow.

According to an embodiment number average fiber length L_N of chemically treated organic natural fiber material may be in the range of 0.5 to 4.0 mm and the fiber length distribution of chemically treated organic natural fiber material is narrow.

According to an embodiment number average fiber length L_N of chemically treated organic natural fiber material may be in the range of 0.05 to 0.5 mm and the fiber length distribution of chemically treated organic natural fiber material is wide.

According to an embodiment number average fiber length L_N of fiber material in the form of chemically treated pulp may be in the range of 0.5 to 4.0 mm and the fiber length distribution of fiber material in the form of chemically treated pulp is wide.

Measuring fiber length from composite

The average fiber length may be measured by microscope techniques (e.g. optical or scanning electron microscope). A method to measure average fiber length may comprise microscopic imaging combined with image analysis. The average fiber length may be determined from a group of individual fibers. In particular, microscopic imaging techniques may be used when measuring the length or number based average fiber length from a composite comprising chemically treated organic natural fiber material. Figure 2 shows, by way of an example, means to perform a fiber length measurement. Optical means such as microscopy may be used to obtain images of one or more non-overlapping areas AREA1 on a composite CMP1 surface. From each image, a number average fiber length L_N and/ or a length average fiber length L_L measurement may be performed on multiple, such as one, two, three, four or preferably five or more, adjacent and non-overlapping surface portions POR1 , POR2, POR3, POR4, POR5 at a distance from each other on a planar composite CMP1 . The measured average fiber length L_N or l_L value of each surface portion may be combined to obtain a spatially averaged measurement value of number average fiber length L_N and/ or a length average fiber length L_L, representing an averaged fiber length and length distribution in a composite CMP1 . When a planar composite CMP1 surface measurement is not available, the surface comprising curvature may be shaved to obtain a planar composite CMP1 surface. The composite CMP1 surface may be a cross-sectional area AREA1 or a surface portion obtained by shaving a composite CMP1 surface to reveal material beneath the outer surface. A surface portion POR1 , POR2, POR3, POR4, POR5 may have a dimension, such as a width or a diameter, which dimension is essentially less than 10 mm, for example less than 5 mm or less than 1 mm. Preferably the distance between two adjacent surface portions is less than the width of a single surface portion. The number and position of the surface portions POR1 , POR2, POR3, POR4, POR5 may be selected based on the shape of the composite CMP1 article, for example by using corners and center of the composite CMP1 surface. Use of multiple surface portions POR1 , POR2, POR3, POR4, POR5 provide more information and may be used to enhance the representativeness of the measurement results. When the measurement from different surface portions POR1 , POR2, POR3, POR4, POR5 on surface is not possible, multiple, preferably five, different samples from the same material may be measured. Use of multiple surface areas AREA1 provide more information and may be used to enhance the representativeness of the measurement results.

Thermoplastic polymer material Organic natural fiber material is typically compounded with a matrix material. When using a composition melt for forming a composite, a thermoplastic polymer material consisting of one or more thermoplastic polymers provides good processability. A suitable thermoplastic polymer material retains sufficient thermoplastic properties to allow melt blending with organic natural fiber material. The thermoplastic polymer material may have effect of enabling providing shaped articles and/or components from the composite. Thermoplastic polymers may be processed by methods such as moulding, extrusion or thermoforming, for example. Furthermore, when a composite has been formed, the organic natural fiber material is protected from the environment by the thermoplastic polymer material, which surrounds the organic natural fiber material in the composite. In particular, thermoplastic polymers which do not absorb moisture are preferable, as such thermoplastic polymers contain mostly surface moisture.

A thermoplastic polymer is a long chain polymer that may comprise amorphous or semi-crystalline structure. A long polymer chain may comprise various lengths of polymer chains, such that the average polymer length is typically above at least 1000 monomers, such as 2000 or 3000 or 5000 or 10000 monomers. In general, the longer the average chain length is, the higher is the average molecular weight of the polymer in daltons (Da). The thermoplastic polymer may be a homopolymer, copolymer, or a blend thereof. The polymers consisting of only one type of repeat units repeated along the polymer chain are referred to homopolymers. Chains composed of two or more different repeat units are termed copolymers. The thermoplastic polymer material preferably contains at least 50 wt.% (weight percent) or at least 50 wt.% (weight percent) or more such as at least 60 wt.%, more preferably at least 70 wt.%, or at least 80 wt.%, and most preferably at least 90 wt.% or at least 95 wt.% of thermoplastic polymer. The thermoplastic polymer may be, for example, polyethylene, polypropylene, polybutylene, polystyrene, poly(acrylic nitrile butadiene styrene) copolymer (ABS), polyamide, aliphatic polyester, aromatic polyester, such as poly(ethylene terephthalate) and polycarbonate, polyether, polyvinyl chloride), thermoplastic elastomer, thermoplastic polyurethane (TPU), polyimide, or a derivative or copolymer of said monomers. The thermoplastic polymer material may alternatively or in addition comprise biodegradable polymer. There are many sources for biodegradable polymers, from synthetic to natural. Bio-based polymers, such as natural polymers (biopolymers), are available from renewable sources, while synthetic polymers are produced from non-renewable petroleum resources. The biodegradable polymer may be at least one of the following: poly(lactic acid) (PLA), poly(glycolic acid) (PGA), polycaprolactone poly(hydroxyl alkanoate) (PHA), polysaccharide, poly(alkene dicarboxylate) such as poly(butylene succinate) and poly(ethylene succinate), poly(butylene adipate-co-terephthalate), and any derivate or copolymer of said monomers, their derivatives, and/or any combinations thereof. The amount of the thermoplastic polymer in the thermoplastic polymer material is at least 80 wt.%, more preferably at least 90 wt.%, and most preferably at least 95 wt.%. The thermoplastic polymer material may comprise 40-98 wt.%, or preferably 60-95 wt.% thermoplastic polymer or polymer composition. A composite may comprise thermoplastic polymer material an amount equal to or more than 45 wt.%, such as equal to or more than 50 wt.%, such as equal to or more than 60 wt.%, such as equal to or more than 70 wt.%. A composite may comprise thermoplastic polymer material an amount equal to or less than 80 wt.%, such as equal to or less than 70 wt.%, such as equal to or less than 60 wt.%, such as equal to or less than 50 wt.%. A composite may comprise thermoplastic polymer material in the range of 5 to 90 wt.%, such as in a range of 45 to 80 wt.%. A composite may comprise thermoplastic polymer material in the range of 10-75 wt.%, more preferably 20-65 wt.%, or most preferably 40-60 wt.%.

Advantageously, the thermoplastic polymer material comprises at least one of crystalline polymer, non-crystalline polymer, crystalline oligomer, noncrystalline oligomer, semi-crystalline polymer and semi-crystalline oligomer or a combination thereof. Semi-crystalline polymers comprise in addition melt temperatures. Semi-crystalline polymers may comprise both crystalline and amorphous portions. Polyolefin, for example a polypropylene, is an example of a semi-crystalline matrix material. Degree of crystallinity for an amorphous thermoplastic polymer material is approaching zero. For a semi-crystalline polymers degree of crystallinity may be 10-80 wt.%, or preferably 20-70 wt.%, or more preferably 40-60 wt.%. Polyolefin may comprise degree of crystallinity of 40-60 wt.%. Polypropylene may comprise degree of crystallinity of 40-60 wt%. Material comprising small molecules may achieve higher degree of crystallinity compared to materials comprising bigger molecules. Methods for evaluating the degree of crystallinity comprise density measurement, differential scanning calorimetry (DSC), X-ray diffraction (XRD), infrared spectroscopy and nuclear magnetic resonance (NMR). The measured value is dependent on the method used. Distribution of crystalline and amorphous regions may be visualized with microscopic techniques, like polarized light microscopy and transmission electron microscopy.

Thermoplastic polymers, which may be used in composites comprising organic natural fiber based material may comprise, for example, polyethylene, polypropylene, polystyrene, acrylonitrile butadiene styrene (ABS), polyvinyl chloride (PVC) or any of their combinations thereof. The thermoplastic polymer may be a polyolefin. The thermoplastic polymer material may comprise, for example, a homopolymer, a copolymer or a modified polymer of unsaturated aliphatic hydrocarbons. Preferred polyolefins are C2- C4 polyolefins, such as polyethylene and polypropylene. Polyethylene and polypropylene are also available in high purity grades without process interfering residues. Other preferred thermoplastic polymers are acrylonitrile butadiene styrene (ABS), polystyrene and polyvinyl chloride (PVC). Acrylonitrile butadiene styrene (ABS) is a low weight terpolymer comprising high impact resistance and which is widely used for extrusion and injection moulding. Polystyrene is a chemically inert thermoplastic polymer. Polystyrene may be expanded to obtain rigid and tough expanded polystyrene (EPS). Expanded polystyrene has low weight and rigidity, and can be used in a composite for wide range of applications. Polyvinyl chloride is a thermoplastic polymer, which has high hardness, but can be made softer and more flexible by adding plasticizers. The above-mentioned thermoplastic polymers do not absorb moisture. Said thermoplastic polymers contain mostly surface moisture, if any at all. A low moisture content is advantageous when obtaining a composite comprising a desiccating process agent. A low composite moisture content, such as equal to or less than 2 % by weight of the composite, provides means to reduce the amount of desiccating process agent introduced into the composite during the manufacturing process. Furthermore, when the moisture content of the thermoplastic polymer is low, less amounts of desiccating process agent are needed to efficiently bind moisture from a given amount of chemically treated organic natural fiber material .

The matrix material may contain one or more of the above-mentioned thermoplastic polymers. Advantageously, at least one thermoplastic polymer is selected from the group consisting of polyethylene, polypropylene and their combinations. Advantageously, the amount of polypropylene or polyethylene in the matrix material is at least 50 wt.%, at least 60 wt.%, at least 70 wt. %, at least 80 wt.%, at least 90 wt.% or at least 95 wt.%.

The thermoplastic polymer material may comprise recycled polymer. Alternatively, the thermoplastic polymer material may comprise virgin polymer. In addition, the thermoplastic polymer material may comprise both recycled polymer and virgin polymer. A virgin polymer may be added to the thermoplastic polymer material The amount of added polymer, such as polypropylene, may depend on the other raw materials used. For example, if recycled polymer material is used, the amount of added virgin polymer may depend on the amount of the different raw materials coming along the recycled material. The thermoplastic polymer material may comprise at least 50 wt.%, or preferably 70 wt.%, or more preferably 95 wt.% of virgin polymer. In an example the thermoplastic polymer material comprises 100 wt.% of virgin polymer. The virgin polymer may have effect of providing better stiffness properties compared to recycled polymer. The thermoplastic polymer material may alternatively or in addition comprise a biodegradable polymer. A suitable biodegradable polymer retains sufficient thermoplastic properties to allow melt blending with organic natural fiber based material. The biodegradable polymer may have effect of enabling providing shaped articles and/or components from the composite, which have an accelerated rate of degradation in comparison to other polymers. Biodegradability may be defined according to standard SFS-EN-13432. Biodegradable polymers may be manufactured and/or shaped by methods such as moulding, extrusion or thermoforming, for example. Thermoplastic polymer material is often solid at low temperatures and forms a viscose polymer melt at elevated temperatures. The low and the elevated temperatures may be defined based on the melting point T_m of the material. A low temperature is a temperature below the melting point T_m of the material . In a low temperature the material in general is in a solid form. In elevated temperatures above the melting point T_m the material begins to melt. Typically the viscosity of the material decreases when temperature is increased, and the material flows and wets the surfaces more easily. When a composite comprising a thermoplastic polymer material is produced, the thermoplastic polymer material is heated in order to melt the polymer, and other components of the composites are mixed with the polymer melt. Often it is easy to mix these other components into thermoplastic polymer material when the viscosity of the thermoplastic polymer material is low, meaning that the temperature of the melt is high. In addition to the melting point T_m, a thermoplastic polymer material may have a glass transition temperature T_g. Furthermore, some thermoplastic polymer material may have a glass transition temperature T_g but not a melting point T_m. In general, when a thermoplastic polymer material has a glass transition temperature T_g and a melting point T_m, the melting point T_m is a higher temperature than glass transition temperature T_g._Advantageously, the melting point T_m of the thermoplastic polymer material is under 250 °C, preferably under 220 °C, and more preferable under 190 °C. Advantageously, the glass transition temperature of the thermoplastic polymer material is under 250 °C, preferably under 210 °C, and more preferable under 170 °C.

Advantageously, melt flow rate, MFR, of the thermoplastic polymer material, may be equal to or under 1000 g/10 min (230°C, 2.16 kg defined by ISO 1 133, valid 201 1 ). Advantageously, melt flow rate, MFR, of the thermoplastic polymer material may be over 0.01 g/10 min (230°C, 2.16 kg defined by ISO 1 133, valid 201 1 ), more preferably over 1 g/10 min, most preferably over 3 g/10 min.

Polymers used as thermoplastic polymer material in general have a molecular weight distribution. When a thermoplastic polymer material has a narrow molecular weight distribution, the thermoplastic polymer material is more homogeneous, which may improve processability and the flow of the material in a melt form, in particular when the average molecular weight is low. When a thermoplastic polymer material has a wide molecular weight distribution, the thermoplastic polymer material may comprise shorter polymer chains having lower molecular weight, and longer polymer chains having higher molecular weight. A wide molecular weight distribution may provide a combination of two or more properties, wherein longer polymer chains (i.e. higher molecular weight) may improve stretching properties of the material (material can be thermoformed more easily) and/or impact strength, while shorter polymer chains (i.e. lower molecular weight) may improve the flow properties during processing. Average molecular weight of the thermoplastic polymer material may be characterized using different methods. One way to characterize polymers is melt flow index MFI, which can be measured according to standard ISO 1 133. The method according to standard ISO 1 133 is an indirect method providing an indirect result representing the average molecular weight of the thermoplastic polymer material. In other words, the standard ISO 1 133 does not measure the molecular weight directly. As an example, a MFI of a first polymer lower than a MFI of a second polymer in general is an indication that the number average molecular weight of the first polymer is higher than that of the second polymer, when both the first and the second polymer are same type of polymers.

Molecular weight distribution of a polymer may be characterized by polydispersity index (PI). Polydispersity index PI is ratio of weight average molecular weight and the number average molecular weight (Mw/Mn). The number average molecular weight is the statistical average of molecular weight of all polymer chains in the sample according to equation 3 below:

Equation 3: Mn = (∑NiMi)/∑Ni , where Mi is the molecular weight of a chain and Ni is the number of chains molecular weight Mi.

The weight average molecular weight may be defined by equation 4 below: Equation 4: Mw = (∑NiMi²)/∑NiMi , where Mi is the molecular weight of a chain and Ni is the number of chains of molecular weight Mi.

Above discussed average molecular weights may be measured by means of gel permeation chromatography (GPC) or means of size exclusion chromatography (SEC), which are techniques known to a person skilled in the art of polymer processing.

Thermoplastic polymer material according to embodiments may be formed into a new shape several times when it is heated. The thermoplastic polymer material keeps its new shape after cooling and then it flows very slowly, or it does not flow at all. The thermoplastic polymer material has at least one repeat unit. Number average molecular weight of the matrix material may be 18-1000 g/mol, or 100-500 g/mol, or 500-1000 g/mol, or 1000-10 000 g/mol, or 10 000-100 000 g/mol , or over 100 000 g/mol .

Molecular weight distribution of the thermoplastic polymer material is narrow, when the polydispersity index is in the range of 1 to 3, more preferably in the range of 1 to 2 and most preferably in the range of 1 to 1 .5. Molecular weight distribution of the thermoplastic polymer material is wide, when the polydispersity index is in the range of 2 to 10, more preferably in the range of 2.5 to 9 and most preferably in the range of 3 to 8. Molecular weight distribution of the thermoplastic polymer material is very wide, when the polydispersity index is in the range of 4 to 40, more preferably in the range of 5 to 30 and most preferably in the range of 6 to 20.

Wide molecular weight distribution can be obtained e.g. by having bimodal molecular weight distribution. This means that there are two maximums in the molecular weight distribution (GPC/SEC) curve.

According to an embodiment MFI of thermoplastic polymer material may be 0.1 -10 g/10 min and molecular weight distribution is narrow.

According to an embodiment MFI of thermoplastic polymer material may be 5-100 g/10 min and molecular weight distribution is narrow.

According to an embodiment MFI of thermoplastic polymer material may be 0.1 - 10 g/10 min and molecular weight distribution is wide. According to an embodiment MFI of thermoplastic polymer material may be 5-100 g/10 min and molecular weight distribution is wide.

Preferably the melt flow index MFI of the thermoplastic polymer material is in the range of 0.01 to 1000 g/10 min or in the range of 0.02 to 900 g/10 min or in the range of 0.04 to 800 g/mol, more preferably in the range of 0.08 to 600 g/10 min or in the range of 0.1 to 500 g/10 min or in the range of 0.2 to 300 g/10 min and most preferably in the range of 1 to 200 g/10 min or in the range of 10 to 180 g/10 min or in the range of 30 to 150 g/10 min. According to another embodiment the melt flow index MFI of the thermoplastic polymer material may be in the range of 0.01 to 1000 g/10 min or in the range of 0.02 to 800 g/10 min or in the range of 0.04 to 600 g/mol, more preferably in the range of 0.08 to 200 g/10 min or in the range of 0.1 to 80 g/10 min or 0.1 1 g to 30 g/10 min and most preferably in the range of 0.12 to 20 g/10 min or in the range of 0.13 to 10 g/10 min or in the range of 0.14 to 5 g/10 min.

According to an embodiment the melt flow index MFI of the thermoplastic polymer material may be below 300 g/10 min or below 200 g/10 min or below 100 g/10 min, more preferably below 80 g/10 min or below 50 g/10 min or below 30 g/10 min, most preferably below 10 g/10 min or below 6 g/10 min or below 3 g/10 min.

Density of a polymer thermoplastic polymer material in a solid form may be approximately 1 g/cm3, for example 0.8-1 .7 g/cm3. For example, low density polyethylene (LDPE) comprises density of 0.840-0.926 g/cm3; medium density polyethylene (MDPE) comprises density of 0.926-0.941 g/cm3, high density polyethylene (HDPE) comprises density of 0.941 -0.990 g/cm3, polypropylene (PP) comprises density of 0.85-0.95 g/cm3, polystyrene (PS) comprises density of 1 .00-1 .150 g/cm3, polylactic acid (PLA) comprises density of 1 .18-1 .50 g/cm3.

A method for obtaining a composite

A method for obtaining a composite comprises providing a composition mixture. A composition mixture may comprise chemically treated organic natural fiber material and thermoplastic polymer material. The method for obtaining a composite comprises providing a composition melt. A composition is obtained by melting the composition mixture. The method for obtaining a composite may comprise introducing a desiccating process agent having a moisture binding capacity. The method for obtaining a composite may comprise forming a composite comprising the chemically treated organic natural fiber material, the thermoplastic polymer material, and the desiccating process agent.

Figure 3 illustrates, by way of an example, a method for obtaining a composite. A composition mixture MIXT1 may be provided by mixing chemically treated organic natural fiber material FIB1 and thermoplastic polymer material MTX1 . The thermoplastic polymer material MTX1 used for mixing may be introduced in a solid form, for example as powder, granules or pellets. The chemically treated organic natural fiber material FIB1 is typically provided in a solid form, for example as large fiber or fiber bundles, pulp chaff or as crushed pulp material. When the composition mixture MIXT1 is processed directly to a composite CMP1 , the mixing may optionally comprise introducing a desiccating process agent DES1 having a moisture VAP1 binding capacity. Alternatively, introducing the desiccating process agent DES1 may be done before melting the composition mixture MIXT1 , such as when providing the composition mixture MIXT1 , when melting the composition mixture MIXT1 , or after melting the composition mixture MIXT1 and before forming the composite CMP1 . The desiccating process agent DES1 may be introduced in a solid form, for example as powder, granules or pellets. The desiccating process agent DES1 may be introduced as such, or as a pre-mixed master batch.

A composition melt MLT1 may be provided by melting the composition mixture MIXT1 . A composition melt MLT1 is obtained, when the thermoplastic polymer material MTX1 is in a melt form. The thermoplastic polymer material MTX1 is in a melt form, when the temperature of the composition mixture MIXT1 is higher than the glass transition point T_g or/and melting point T_m of thermoplastic polymer material MTX1 . When mixing or melting the composition mixture MIXT1 , heat may be provided to the process. For example, a process temperature in the range of 140°C to 220°C may be obtained. Preferably, the process temperature is selected such that the temperature of the composition mixture MIXT1 is above the glass transition point T_g and/or the melting point T_m of the thermoplastic polymer material MTX1 , and below a temperature, organic natural fiber material FIB1 may begin to decompose or deteriorate. When chemically treated organic natural fiber material is used, a process temperature equal to or below 220°C is preferred.

The method may comprise arranging at least partial evaporation of moisture VAP1 from the composition mixture MIXT1 or the composition melt MLT1 by heating before introducing the desiccating process agent DES1 . The method may comprise heating the composition mixture MIXT1 or the composition melt MLT1 to a temperature tp2 of at least 100°C or higher before introducing the desiccating process agent DES1 . The method may comprise heating the composition melt MLT1 to a temperature tp3 of at least 140°C or higher, such as in the range of 140°C to 220°C before introducing the desiccating process agent DES1 . Heating the composition mixture MIXT1 or the composition melt MLT1 may be done to reduce the fiber moisture content w_Fi . For example, a chemically treated organic natural fiber material FIB1 may have a moisture content w_Fi equal to or the less than 2.0 wt%, preferably less than 1 .75 wt.% or 1 .5 wt.%, most preferably less than 1 .0 wt.% or 0.5 wt.%, such as 0.3 wt.%, The chemically treated organic natural fiber material FIB1 may have a moisture content w_Fi for example in the range of 0.05 wt.% to 2.0 wt.%, or in the range of 0.05 wt.% to 1 .75 wt.%, for example in the range of 0.05 wt.% to 1 .5 wt.% or in the range of 0.05 wt.% to 1 .0 wt.%. A small fiber moisture content w_Fi enables reduced amounts of the desiccating process agent DES1 to be used. The amount of desiccating process agent DES1 added may be equal to or less than 5 wt.%, such as equal to or less than 3 wt.%, such as equal to or less than 2 wt.% or equal to or less than 1 .5 wt.% or equal to or less than 1 wt.% of the formed composite CMP1 . The amount of desiccating process agent DES1 added may be equal to or more than 0.3 wt.%, such as equal to or more than 0.5 wt.%, such as equal to or more than 1 wt.%, such as equal to or more than 1 .5 wt.% or equal to or more than 2 wt.%.The amount of desiccating process agent (DES1 ) in the composite (CMP1 ) may be in the range of 0.3 wt.% to 5 wt.%, such as in the range of 0.5 wt.% to 3 wt.% or in the range of 0.5 wt.% to 2 wt.% of the weight of the composite (CMP1 ). Some desiccating process agents, such as mineral oxides, may react with other compounds. Providing means to reduce the amount of desiccating process agent in a composite are thus desirable.

Temperatures tp2 and tp3 refer to process parameter values in a method for obtaining a composite, as presented in Figure 7.

Forming the composite CMP1 may comprise a process, wherein the composition melt MLT1 is introduced in the direction of the melt flow DIRMD- An extrusion process or a moulding process are examples of such processes. Sheet extrusion, co-extrusion, injection moulding or rotation moulding are examples of processes where chemically treated organic natural fiber material may be used. In particular, methods such as sheet extrusion and thermoforming using composite comprising chemically treated organic natural fiber material FIB1 may be especially sensitive to the presence of moisture in the composite CMP1 . Such processes benefit of using a desiccating process agent DES1 and reducing the fiber moisture content w_Fi of the chemically treated organic natural fiber material. Forming the composite from a composite melt MLT1 may comprise cooling, to provide a solid form for the composite CMP1 .

Figure 4 illustrates, by way of an example, the use of intermediate products for obtaining a composite. The method for obtaining a composite CMP1 may comprise providing the composition mixture MIXT1 by mixing a preliminary composite product TMP1 . A preliminary mixture MIXT2 comprising chemically treated organic natural fiber material FIB1 and thermoplastic polymer material MTX1 may be obtained by mixing. The method may comprise melting the preliminary mixture MIXT2 comprising chemically treated organic natural fiber material FIB1 and thermoplastic polymer material MTX1 . The preliminary mixture MIXT2 may be melted into a preliminary composition melt MLT2. The method may comprise forming a preliminary composite product TMP1 , such as a spherical, cylindrical or granular intermediate product. The preliminary mixture MIXT2 may be obtained without adding a desiccating process agent DES1 . The preliminary composite product TMP1 may be stored. When the preliminary composite product TMP1 comprises cavities, such as closures or voids inside the material comprising gaseous material, it may have an effect on a further process where the preliminary composite product TMP1 is used. The method may comprise providing the composition mixture MIXT1 by mixing the preliminary composite product TMP1 . The mixing of preliminary composite product TMP1 into the composition mixture MIXT1 may optionally comprise introducing a desiccating process agent DES1 having a moisture VAP1 binding capacity. The preliminary composite product TMP1 provides means of selecting a later phase for introducing a desiccating process agent DES1 having a moisture VAP1 binding capacity. The preliminary composite product TMP1 provides means to compound the chemically treated organic natural fiber material with the thermoplastic polymer material MTX1 prior to adding the desiccating process agent DES1 . The method may comprise arranging at least partial evaporation of moisture VAP1 from the preliminary composition mixture MIXT2 or the preliminary composition melt MLT2 by heating before introducing the desiccating process agent DES1 .

Moisture content When producing composite comprising chemically treated organic natural fiber material, water may be present in the chemically treated organic natural fiber material as adsorbed moisture. When processing composition melt comprising chemically treated organic natural fiber material during manufacturing of a composite, a high fiber moisture content may be a problem.

Water may be present in organic natural fiber material in different forms. Water molecules may be present in the fiber material closely associated with individual fiber molecules, as 'water of crystallization', or as water molecules which are non-bound moisture referred to as 'free water'. A chemically treated organic natural fiber material may comprise a high fiber moisture content w_Fi above 2 wt.% of the total weight of the chemically treated organic natural fiber material. Some water molecules, referred to as residual water, may remain attached on the cellulose fibers through hydrogen bonding. Residual water is moisture present in organic natural fiber material after evaporation at a temperature higher than the boiling point of water. Evaporation at a temperature higher than 100°C, such as in the range of 105°C, is typically used to determine the fiber moisture content w_Fi present in chemically treated organic natural fiber material . Water bound to the cellulose fibers through hydrogen bonding may not yet evaporate at a temperature in the range of 100°C, but may require a higher temperature. Heating organic natural fiber material to a temperature such as at least 140°C, such as at least 170°C or at least 200°C, may be used to evaporate water bound through hydrogen bonding.

Preferably, after arranging at least partial evaporation of moisture, chemically treated organic natural fiber material has a fiber moisture content w_Fi in the range of equal to or less than 2 wt.% or equal to or less than 1 .0 wt% of the total weight of the organic natural fiber material. More preferably, the fiber moisture content w_Fi is in the range or equal to or less than 0.8 wt.%, such as equal to or less than 0.7 wt.%, or equal to or less than 0.6 wt.%, such as equal to or less than 0.5 wt.%, or equal to or less than 0.3 wt.%, such as equal to or less than 0.2 wt.%, or equal to or less than 0.1 wt.%, or equal to or less than 0.01 wt.% of the total weight of the organic natural fiber material. Preferably, after arranging at least partial evaporation of moisture, the fiber moisture content w_Fi may be in the range of 0.01 wt.% to 2 wt.%, such as in the range of 0.01 wt.% to 1 wt.%, more preferably the range of 0.01 wt.% to 0.8 wt.%, such as in the range of 0.01 wt.% to 0.6 wt.%. When the fiber moisture content w_Fi is high, such as above 2 wt.% or above 5 wt.%, the residual water may cause problems in manufacturing of a composite. In particular, when forming a composite, the process temperature and pressure may be sufficiently high for breaking hydrogen bonds between water molecules and the hydroxyl groups in the organic natural fibers, resulting in formation of free water. The free water may evaporate as moisture from the organic natural fiber material, and the conditions such as temperature and pressure in the composite melt processing may be sufficient to sustain the water in a liquid state. However, when the composite is formed, for example by extrusion, the decreasing pressure may lead to rapid evaporation of the water. The evaporating water may create cavities comprising air or other gaseous substances. The evaporating water may create defects on the composite surface. Some equipment used for forming a composite product do not remove air during the composition melt processing. The presence of air in such a system may cause the formed composite product to have surface defects, such as cracks or scratches in the surface, colour defects in the surface or bubbles in the composite material. In particular, methods such as sheet extrusion and thermoforming using composite comprising chemically treated organic natural fiber material may be especially sensitive to the presence of moisture in the composite. Evaporation by heat may be used to reduce the moisture content of organic natural fiber materials used for composite manufacture. In particular, evaporation by heat may be used before mixing the chemically treated organic natural fiber material with a thermoplastic polymer material. Heating may further be used during processing to reduce moisture from a composition mixture or melt. Heating may be provided for example by device such as a dryer or a mixer device arranged to provide thermal energy. Evaporation by heat may be, for example performed at temperature of 105°C. The quantity of water contained in a material may be given on a volumetric or mass (gravimetric) basis. Moisture content or fiber moisture content w_Fi may be measured using a known mass of the material, and a drying oven.

Measurement of a moisture content from composite

The methods used above may also be used to measure the moisture content of a composite product comprising chemically treated organic natural fiber material . Several methods, such as chemical, spectroscopic, gravimetric, thermal, electrical, and physical test methods are available for measurement of moisture content in different materials. For example, a method to analyse moisture content can be based on a technique such as Karl Fischer titration, infrared, nuclear magnetic resonance, direct weight loss, thermogravimetry, differential thermal analysis, conductance, coulometry or azeotropic distillation. The fiber moisture content w_Fi of chemically treated organic natural fiber material, moisture content of a composite or moisture content of a preliminary composite product may preferably be measured according to ISO standard 638:2008. The measurement is a loss of weight method. The ISO standard 638:2008 is modified such that the weight of sample is measured before and after heating the sample at temperature of 105°C for 24 hours at atmospheric pressure in a typical laboratory circulating air oven and after equilibration in a desiccator, and measuring the loss of weight from the sample due to heating in the oven. The moisture content is determined as loss of weight according to equation 5 below:

Equation 5: Moisture content (%) = 100 %*(rrii - m_a)/m_\ , where m, is the weight of the sample before drying and m_a is the weight of the sample after drying.

Advantageously, the volume of the sample is below 1 % of the volume of the oven.

A desiccating process agent

Some compounds, such as calcium carbonate in plastics, have been conventionally used as filler material to reduce the consumption of more expensive binder materials.

A desiccating process agent refers to material which, after addition to a mixture or composition melt, may react with water or bind water under the melt processing conditions. A desiccating process agent may also be referred to as a drying agent. A desiccating process agent is capable of physically or chemically binding water. The fiber moisture content w_Fi during composite manufacture may be controlled by addition of a desiccating process agent. The desiccating process agent may be inert, such as silica gel or an aluminosilicate based compound (zeolite). The desiccating process agent may be reactive, such as an inorganic mineral compound. The desiccating process agent may be a mineral oxide. Some examples of mineral oxides are calcium oxide, magnesium oxide or zinc oxide. The desiccating process agent may be a stearate. Some examples of stearates are calcium stearate, sodium stearate or zinc stearate. The desiccating process agent may be a mineral sulphate. An example of a mineral sulphate is magnesium sulphate.

A physical binding of a water in a desiccating process agent refers to water molecules associated closely with the desiccating process agent or water molecules. The physical binding of a water may involve relatively weak intermolecular forces, such as van der Waals forces and/or electrostatic interactions, between the water molecule and the surface of the desiccating process agent. A desiccating process agent acting through physical binding may form, for example structures comprising crystallized water. Desiccating process agents which physically bind water are, for example, various salts, copper sulphate, magnesium aluminum silicate (montmorillonite clay), silicon dioxide (silica) and synthetic porous crystalline aluminosilicates (molecular sieves, such as zeolites). In particular, molecular sieve comprising a synthetic aluminosilicate may be engineered to have a controlled pore size. A controlled pore size may be used to form a very strong affinity for specifically sized molecules. For example, a small pore volume, such as in the range of 3 angstrom units, may be used to allow adsorption of water vapour, while at the same time exclude other molecules, such as hydrocarbons. In general, the physical binding of water molecules may be exothermic. The strength of the physical bond may be measured by heat of adsorption. A high heat of adsorption value for moisture on a desiccating process agent reflects a strong bonding. A strong bonding means that it is more difficult to remove moisture. A chemical binding of a water in a desiccating process agent in general involves a chemical reaction, where the desiccating process agent reacts with water. Such chemical reaction may form a status of equilibrium, where the water may shift between two states with respect to the desiccating process agent. In a first state the water may be free water, whereas in the second state the water maybe chemically bound to the desiccating agent. Examples of desiccating process agent acting through chemical binding are mineral oxides such as calcium oxide, aluminium oxide and magnesium oxide. Other mineral compounds such as stearates or mineral sulphates such as magnesium sulphate may further be used as desiccating processing agents. Desiccating process agents acting through chemical binding, in particular mineral oxides such as calcium oxide, may further have an effect on the pH of the composite.

Some desiccating process agents, such as hydrotalcites, calcium, sodium and zinc stearates, zinc oxide, and calcium lactate and lactylate may further be used as acid scavengers in base stabilization of polyolefins, where they participate in neutralization of acidic catalyst residues.

The addition of a desiccating process agent to organic natural fiber material or a mixture or composite melt comprising organic natural fiber material may be used to bind residual moisture content in the material.

Effects of desiccating process agent

Desiccating process agents are sensitive to moisture. Late addition of a desiccating process agent improves the moisture binding effect of the desiccating agent and provides means to reduce the amounts added. The desiccating process agent may be added to a process in different phases. The desiccating process agent may be added to a manufacturing process in one or more phases. A suitable desiccating process agent is capable of physically or chemically binding water in a material mixture when forming a composite. In particular, a desiccating process agent having capacity of physically or chemically binding water in a composition melt under manufacturing process conditions is preferred. The method for obtaining a composite may comprise a manufacturing process temperature in the range of at least 100°C, preferably at least 140°C, such as in the range of 140°C to 220°C. When forming a composite, the pressure used in a process may be reduced and residual water present in the material may form vapour and evaporate. Mineral oxides react with other compounds. A desiccating process agent forming a chemical reaction may therefore provide functionality to the composite. Desiccating process agents acting through chemical binding are particularly suitable for binding moisture, as the process temperatures and conditions typically are favorable for moisture binding. In particular, mineral oxides, such as calcium, magnesium and zinc oxides may be used. Calcium oxide is a industrially available mineral oxide and may be obtained in different forms, which facilitate the introduction of the material to the manufacturing process.

Desiccating process agent may further provide means to improve the processability of a composite melt, for example by changing the density of the material and/or by providing melt strength.

Heating the composition melt may further be used to reduce the fiber moisture content before introducing the desiccating process agent. Mineral oxides such as calcium oxide form a chemical reaction with water. The use of a mineral oxide to bind water produces a respective alkaline hydroxide. Due to the reaction, for example, calcium oxide reacts with water and calcium hydroxide is formed.. Calcium hydroxide is highly alkaline compound. A desiccating process agent may thus have an effect on the pH level of the formed composite. Alkaline pH levels caused by a desiccating process agent such as calcium oxide may lead to further chemical reactions such as formation of hydroxides and carbonates. Such reactions may be accelerated, when the amount of desiccating process agent used in the manufacturing process is increased. A desiccating process agent may lead to unwanted colouring (yellowing) of the cellulose fibers and change the appearance and/or other mechanical properties of the composite. Providing means to reduce the amount of desiccating process agent in a composite are thus desirable.

The transformation of a mineral oxide to a hydroxide is a rapid process, which takes place essentially when the moisture content w_F2 is reduced to a lower level w_F3. The process may, however, slowly continue such that the hydroxide is carbonated, for example, when calcium oxide (CaO) forms calcium hydroxide Ca(OH)₂ and eventually calcium carbonate (CaCOs). The presence of a mineral hydroxide in a composite or in a composite product is therefore an indication of a use of a method to obtain a composite comprising desiccating processing agent. Calcium oxide is a particularly preferred desiccating processing agent, as integrated pulp and paper plants typically comprise a lime kiln, which produces large amounts of calcium oxide. The same plants may therefore provide both chemically treated organic fiber material and desiccating processing agent.

Advantageously, arranging at least partial evaporation of moisture from the composition mixture or the composition melt by heating may be done to reduce the fiber moisture content w_Fi . For example, heating the composition mixture or the composition melt to a temperature of at least 100°C, such as at least 140°C or higher, such as in the range of 140°C to 220°C may be done to reduce the fiber moisture content, before introducing the desiccating process agent. Amounts of desiccating process agent

When the moisture content of the organic natural fiber material is measured, the amount of desiccating process agent to be added may be determined based on the measurement result of the moisture content of the organic natural fiber material. The modified ISO standard 638:2008, as described above, may be used for moisture content measurement of chemically treated organic natural fiber material.

When the moisture content of the organic natural fiber material is equal to or less than 2.0 wt.%, the desiccating process agent may be added in an amount of equal to or less than 5 wt.%, such as equal to or less than 3 wt.%, such as equal to or less than 2 wt.% or equal to or less than 1 .5 wt.% or equal to or less than 1 wt.% of the formed composite. The amount of desiccating process agent added may be equal to or more than 0.3 wt.%, such as equal to or more than 0.5 wt.%, such as equal to or more than 1 wt.%, such as equal to or more than 1 .5 wt.% or equal to or more than 2 wt.%.The amount of desiccating process agent in the composite may be in the range of 0.3 wt.% to 5 wt.%, such as in the range of 0.5 wt.% to 3 wt.% or in the range of 0.5 wt.% to 2 wt.% of the weight of the composite. Table 1 below shows examples of a desiccating process agent amounts which may be added in different composite compositions. The amounts of organic natural fiber material in the form of chemically treated pulp (Fiber), thermoplastic polymer material (Matrix) and desiccating process agent (Desiccant) are given as weight percentages. The residual water content of the organic natural fiber material (Fiber water content) for each example has been indicated as weight percentage, when measured from the organic natural fiber material (Fiber) according to the modified ISO standard 638:2008, as described above. The moisture content in a composite comprising the desiccating process agent (Desiccant) is given as weight percentage of the composite, when measured according to the modified ISO standard 638:2008, as described above.

Table 1 . Examples 1 to 8, of amounts of fiber material, thermoplastic polymer material and desiccating process agent used when forming a composite, moisture content w_Fi of the fiber material before addition of desiccating process agent and moisture content of the composite material after addition of desiccating process agent.

As can be seen from the table, when using equal to or less than 50 wt.% of chemically treated organic fiber material, the fiber moisture content w_Fi may be less than 1 .0 wt.%, such as equal to or less than 0.8 wt.%, or equal to or less than 0.5 wt.%, or equal to or less than 0.3 wt.%, such as equal to or less than 0.25 wt.%, equal to or less than 0.2 wt.%, or in the range of 0.15 wt.% or more. Desiccating process agent may be used in an amount equal to or less than 2 wt.%, such as equal to or less than 1 wt.%. Use of the desiccating process agent in an amount equal to or less than 2 wt.% may be used to reduce the moisture content of the composite material to a level equal to or below 0.5 wt.% or 0.25 wt.%, preferably to a level equal to or below 0.1 wt.% or 0.05 wt.%, most preferably in the range of 0.02 to 0.5 wt.%.

In this context, weight percentage (wt.%) refers to the percentage by weight of a component, such as chemically treated organic fiber material, thermoplastic polymer material or desiccating process agent, added into the process. The components may be added separately, at different phases of the manufacturing process or all at the same time. In this context, chemically treated organic fiber material, thermoplastic polymer material and desiccating process agent are used to form a composition melt. For example, in a 100 kilograms (kg) of composite comprising 40 wt.% of chemically treated organic fiber material, 58 wt.% of thermoplastic polymer material and 2 wt.% of desiccating process agent, the amount of desiccating process agent added is 2 kilograms (kg).

Moisture content of a composition melt

In a method for obtaining a composite, the moisture content of a composition melt before introducing desiccating process agent may be below 2.0 wt.% or below 1 .5 wt.% or below 1 .0 wt.%, more preferably below 0.7 wt.% or below 0.4 wt.%, most preferably below 0.29 wt.%, or below 0.26 wt.% or below 0.23 wt.%. The moisture content of a composition melt comprising desiccating process agent may be in the range of 0.01 to 2.0 wt.%, more preferably in the range of 0.01 1 to 1 .0 wt.% or 0.012 to 0.8 wt.%, most preferably in the range of 0.013 to 0.5 wt.% or 0.014 to 0.3 wt.% or in the range of 0.015 to 0.29 wt.% or in the range of 0.016 to 0.25 wt.%.

Moisture content of a composition mixture In a method for obtaining a composite, the moisture content of a composition mixture before introducing desiccating process agent may be below 2.0 wt.% or below 1 .5 wt.% or below 1 .0 wt.%, more preferably below 0.7 wt.% or below 0.4 wt.%, most preferably below 0.29 wt.%, or below 0.26 wt.% or below 0.23 wt.%. The moisture content of a composition melt comprising desiccating process agent may be in the range of 0.01 to 2.0 wt.%, more preferably in the range of 0.01 1 to 1 .0 wt.% or 0.012 to 0.8 wt.%, most preferably in the range of 0.013 to 0.5 wt.% or 0.014 to 0.3 wt.% or in the range of 0.015 to 0.29 wt.% or in the range of 0.016 to 0.25 wt.%.

Moisture content of a preliminary composite product

In a method for obtaining a composite, the moisture content of a preliminary composite product may be less than 2.0 wt.%, preferably less than 1 .5 wt.% or 1 .0 wt.%, most preferably less than 0.5 wt.% or 0.3 wt.% of the weight of the preliminary composite product. Moisture content of a composite

A composite comprising chemically treated organic natural fiber material, thermoplastic polymer material and desiccating process agent may have a moisture content of less than 2.0 wt.%, preferably less than 1 .5 wt.% or 1 .0 wt.%, most preferably less than 0.5 wt.% or 0.3 wt.% of the weight of the composite. The composite may have a moisture content in the range of 0.05 wt.% to 2.0 wt.%, or in the range of 0.05 wt.% to 0.5 wt.% of the weight of the composite. Table 2 below shows examples of measured moisture contents of a composite comprising 20 wt.% of chemically treated organic natural fiber material (chemical pulp) and ca. 80 wt.% (SMP3), ca. 79 wt.% (SMP2), or ca. 78 wt.% (SMP1 ) or a thermoplastic polymer material (polypropylene). The amount of desiccating process agent added into the composition melt has been either 2 wt.% (SMP3), 1 wt.% (SMP2) or 0% (SMP1 ). The used desiccating process agent was calcium oxide (CaO). Before introducing the desiccating process agent, the moisture content of the composite material was in the range of 0.2 to 0.25 wt.%. After forming the composite, each composite sample was dried in an oven for a period of 24, 48, 76 or 96 hours, after which the moisture content (wt.%) of the dried composite sample was measured according to modified ISO standard 638:2008, as described above.

Table 2. Examples of the effect of addition of 0 wt.% 1 wt.% or 2 wt.% of a desiccating process agent (CaO) to a composite moisture content, when added into a composition melt prior to forming the composite.

It may be observed, that before the addition of a desiccating process agent, the moisture content of the composite melt was in the range of 0.2 to 0.25 wt.%. After addition of the desiccating process agent of at least 1 wt.%, the moisture content of the composite was in the range of 0.03 to 0.04 wt.%. After addition of the desiccating process agent of at least 2 wt.%, the moisture content of the composite was in the range of 0.01 to 0.02 wt. In comparison, without addition of a desiccating process agent, the moisture content of the composite was in the range of 0.21 to 0.27 wt.%. The addition of less than 5 wt.%, such as less than 3 wt.% of desiccating process agent to a composition melt comprising chemically treated organic natural fiber material therefore improves the processability of the composition melt and may be used to reduce the moisture content of the composite material. According to an embodiment, addition of at least 1 wt.% of the desiccating process agent to a composition melt comprising equal to or less than 0.3 wt.% of moisture may be used to reduce the moisture content in a ratio of 5:1 . In other words, 1 wt.% of the desiccating process agent may reduce the moisture content up to 80%. According to an embodiment, addition of at least 2 wt.% of the desiccating process agent to a composition melt comprising equal to or less than 0.3 wt.% of moisture may reduce the moisture content in a ratio of 10:1 . In other words, 2 wt.% of the desiccating process agent may reduce the moisture content up to 90%. Therefore, depending on the moisture content level of the composition melt, the amount of a desiccating process agent may be selected to obtain a desired moisture content level on the composite.

Moisture uptake in composite product

Moisture uptake from the atmosphere may be measured from composite products. Before the measurement the composite products may be dried. The composite may be dried at temperature of 120^°C for 24 hours or more before the measurement. Advantageously, the drying temperature is selected to be at least 10^°C lower than a glass transition temperature T_g or a melting temperature T_m of the matrix material. If the drying temperature is lower than 1 10^°C, drying temperature shall be as high as possible, drying preferably accomplished at a vacuum oven (vacuum level preferable below 0.01 mbar), and using drying time of 24 hours or more. For a moisture uptake measurement at least 10 grams of composite material is placed on a plate. When granulates are used, only one granulate layer should be on the plate. The moisture uptake is measured as a weight increase compared to the weight of dried products in the beginning of the measurement. As an example, a composite having an initial weight of 10.0 g, which during the measurement is increased from 10.0 g to 10.1 g, has a 1 .0 wt.% moisture uptake. The measurements are performed in conditions of 22 ^°C temperature and 50 % relative humidity (RH) air moisture. Different measurement times may be used. Table 3 below presents examples of moisture content for composite material comprising chemically treated organic fiber material 20 wt.%, 30 wt.%, 40 wt.% or 50 wt.%. The moisture uptake from the atmosphere has been measured from composite products dried at temperature of 120 °C for at least 24 hours before the measurement, Table 3. Moisture (wt.%) of composite material comprising chemically treated organic fiber material in an amount of 20 wt.%, 30 wt.%, 40 wt.% or 50 wt.%.

A method to obtain composite by means of extrusion

Figure 5 illustrates, by way of an example, a method for obtaining a composite by extrusion. The extrusion may comprise for example sheet extrusion, foam extrusion, wire and cable extrusion, fibre, filament and tape extrusion, pipe extrusion or extrusion method comprising casting or coating. The extrusion may be a single layer or multi-layer extrusion method. When a composite CMP1 comprises a maximum thickness D_max of a few millimeters, such as in the range of 30 micrometers to ten millimeters, for example in the range of 30 micrometers to 120 micrometers, or in the range of 100 micrometers to 10000 micrometers, or in the range of 400 micrometers to 10000 micrometers, preferably in the range of 400 micrometers to 8000 micrometers, most preferably in the range of 400 micrometers to 6000 micrometers, the extrusion method may comprise film extrusion methods such as BOPP, blown or cast film extrusion. The composition melt MLT1 may be pressed by a screw INPUT1 towards a die 300. The die 300 may comprise a nozzle 301 , such as a shaped tip, having a desired profile for shaping the composition melt MLT1 to a composite product. At the nozzle 301 of die 300 the composition melt MLT1 may be expelled through the die 300 having a temperature T300 in the direction of the melt flow DIRMD- The extruded composite CMP1 may comprise a first surface layer 100a having a first surface 101 and a first temperature T1 and an interior layer 100b having a second temperature T2. The first temperature T1 at the surface layer 100a of the composite CMP1 in general may be lower than the second temperature T2 in the interior layer 100b of the composite CMP1 . The extruded composite CMP1 may further comprise a second surface 202, and the extruded composite CMP1 may comprise a top surface layer 100d having a second surface 102, having a third temperature T3. The top surface layer 100d may differ from the first surface layer 100a. The first surface layer 100a may be cooled down by a unit 400. The unit 400 may have a surface 401 and a temperature T400, which may be less than the temperature T1 of the first surface layer 100a. The temperature T400 may be, for example, in the range of 20°C to 120°C, such as in the range of 20°C to 80°C or in the range of 30°C to 70°C. The unit 400 may be a cooling by various means, such as by air or by water or by direct contact to a surface or by a combination of these.

The first temperature T1 , the second temperature T2 and the third temperature T3 may selected such that the composition melt is in a melt form. Preferably, at the nozzle 301 of die 300, the first temperature T1 , the second temperature T2 and the third temperature T3 are above the melting point T_m and/or above the glass transition temperature T_g of the selected matrix material. Advantageously, the melting point T_m of the matrix material is under 250 °C, preferably under 220 °C, and more preferable under 190 °C. Advantageously, the glass transition temperature T_g of the matrix material is under 250 °C, preferably under 210 °C, and most preferably under 170 °C.

A method to obtain composite from a preliminary composite product

A preliminary composite product may be used in method for obtaining a composite. According to an example and referring to Figure 4, a method for obtaining a composite CMP1 may comprise:

melting a preliminary mixture MIXT2 comprising chemically treated organic natural fiber material FIB1 and thermoplastic polymer material MTX1 ; forming a preliminary composite product TMP1 , such as a spherical, cylindrical or granular intermediate product; providing a composition mixture MIXT1 by mixing the preliminary composite product TMP1 , which composition mixture MIXT1 comprises chemically treated organic natural fiber material FIB1 having a fiber moisture content w_Fi , and thermoplastic polymer material MTX1 ;

- providing a composition melt MLT1 by melting the composition mixture MIXT1 ;

introducing a desiccating process agent DES1 having a moisture VAP1 binding capacity; and

forming a composite CMP1 comprising the chemically treated organic natural fiber material FIB1 , the thermoplastic polymer material MTX1 and the desiccating process agent DES1 .

Figure 6 illustrates, by way of an example, a method for obtaining an intermediate product by extrusion. In particular, when forming the intermediate product by extrusion, the die unit 300 may be used to obtain small particles P10, which may be intermediate products. The composition melt MLT1 may be arranged to flow in the direction of the melt flow DIRMD towards the die 300. At the die 300, the composition melt MLT1 may be expelled through the die 300 forming a composite CMP1 . The die 300 may comprise means 340, such as pinholes and a cutting unit, to cut the formed composite CMP1 into one or more small particles P10. The small particle P10 may be a particle having a volume less than 2 cm³, such as a pellet or a granulate. The small particle P10 may be a preliminary composite product TMP1 , such as described in Figure 4. The small particle P10 may be cooled down by a unit, such shown in Figure 5. In particular, when using a desiccating process agent to obtain a small particle P10, the formed particle P10 may comprise less porosity. Therefore, a water cooling unit may be used, operating under constant pressure, such as by means of counter pressure, to cool down the formed small particle P10. When processing one or more small particles P10 further, absorbed moisture may be removed from the small particles P10 by evaporation to at least some extent prior to processing the small particles P10 to a shaped composite product.

The extrusion process, such as a sheet extrusion, may be combined with other processing methods, such as thermoforming, to provide a desired shape for the composite. Parameters in a method to obtain composite

Figure 7 illustrates, by way of an example, effects of some process parameters as a function of time in a method for obtaining a composite comprising chemically treated organic natural fiber material. In particular, when a desiccating process agent is added, some properties of the obtained composite product may be selected. The method may comprise time points tO and t1 . Within the period between time points tO and t1 , referred to as a starting period, a composition mixture which comprises chemically treated chemically treated organic natural fiber material and thermoplastic polymer material may be provided. The composition mixture may be obtained by mixing the chemically treated organic natural fiber material and the thermoplastic polymer material. The method may comprise a temperature tp1 , referred to as the starting temperature. The temperature tp1 is the temperature of the manufacturing process, such as the mixing device, at time point tO, when the chemically treated organic natural fiber material and thermoplastic polymer material are provided into the mixing device. In general, the chemically treated organic natural fiber material and thermoplastic polymer material have a temperature in the same range as the manufacturing process. The chemically treated organic natural fiber material and/or the thermoplastic polymer material may be at the temperature tp1 , when provided into the mixing device. The temperature tp1 may be selected to be above 20°C. The temperature tp1 may be selected to be below the glass transition point T_g or the melting point T_m of the thermoplastic polymer material. The temperature tp1 may be, for example, in the range of 20°C to 90°C, such as in the range of 20°C to 80°C or in the range of 30°C to 70°C.

The method may comprise a pressure p1 , referred to as the starting pressure. The pressure p1 is the pressure inside the manufacturing process, such as inside the mixing device, at time point tO, when the chemically treated chemically treated organic natural fiber material and thermoplastic polymer material are provided into the mixing device. The pressure p1 may be equal to atmospheric pressure. When using a vacuum mixing device, the pressure p1 may be less than the atmospheric pressure. The pressure p1 may be substantially constant during the starting period.

The method may comprise introducing a desiccating process agent having a moisture binding capacity. The concentration of the desiccating process agent Cd_es may increase during the manufacturing process. At time point to, the concentration of the desiccating process agent Cd_es may be substantially zero. In other words, the desiccating process agent may be introduced later into the process.

At time point to, the composition mixture may comprise moisture. At time point tO, the fiber moisture content w_Fi of the organic natural fiber material may be in the range of equal to or less than 2 wt.%. The method may comprise arranging at least partial evaporation of moisture from the composition mixture or the composition melt by heating. Between time points t1 and t2, referred to as an evaporation period, the manufacturing process temperature TP(t) is increased from the initial temperature tp1 to a temperature tp2 or higher to a temperature tp3. The method may comprise heating the composition mixture or the composition melt to a temperature tp2. The temperature tp2 may be selected to be above the boiling point of water. The temperature tp2 may be selected to be at least 100°C or higher, such as at least 105°C. A temperature in the range of 105°C to 120°C may be used for evaporation of moisture. Heating to temperature tp2 may be used to reduce the fiber moisture content w_Fi , before introducing the desiccating process agent. The method may comprise heating the composition mixture or the composition melt to a temperature tp3. The temperature tp3 may be selected to be above the glass transition point T_g or/and the melting point T_m of the thermoplastic polymer material. The temperature tp3 may be selected to be at least 140°C or higher, such as at least 170°C. A temperature tp3 in the range of 140°C to 220°C may be used when processing composition mixture comprising organic natural fiber material and a thermoplastic polymer material . Heating to temperature tp3 may be used to reduce the fiber moisture content w_Fi , before introducing the desiccating process agent. During the evaporation period, the pressure p1 of the manufacturing process may be maintained essentially at the same level as in the initial period. Increasing the manufacturing process temperature TP(t) from the temperature tp1 to a higher temperature tp2 or tp3 may be used to reduce the moisture content w_Fi to a lower level, referred to as moisture content w_F2- The moisture content w_F2 represents the moisture content level remaining, after at least partial evaporation of moisture from the composition mixture or the composition melt by heating. During the evaporation period, the evaporating water vapour may increase from a starting level w_V2 to a higher level w_vi . The water vapour refers to the amount of relative humidity of a closed system in the process. The closed system may be a production unit used for processing the composite mixture and/or the composite melt. In the beginning of the process, at time point to, the relative humidity may be equal to the ambient humidity. In an enclosed space, the evaporation of moisture from the composition mixture or the composition melt increases the relative humidity of the closed system, and leads to a higher water vapour level w_vi than the ambient humidity.

The desiccating process agent may be introduced to the composition mixture or the composition melt. A desiccating process agent may be added to the mixture at time point t2. The desiccating process agent may be added to the mixture between time points t2 and t3, referred to as a desiccating process agent addition period. The method may comprise introducing the desiccating process agent before melting the composition mixture. The desiccating process agent may be introduced when providing the composition mixture. The method may comprise introducing the desiccating process agent when melting the composition mixture. The method may comprise introducing the desiccating process agent after melting the composition mixture and before forming the composite. Before introducing the desiccating process agent, the composition mixture or the composition melt may be heated to a temperature tp2 or higher to a temperature tp3. Preferably, the desiccating process agent is introduced in a later phase. A late addition of the desiccating process agent improves the evaporation and may be used to reduce the concentration Cd_es of desiccating process agent in the composition melt. After introducing the desiccating process agent having a moisture binding capacity, the desiccating process agent begins to bind moisture from the composite mixture or the composite melt. In an enclosed space, after introducing the desiccating process agent, the water vapour begins to decrease from higher level w_vi closer to the ambient humidity. A desiccating process agent functional at manufacturing process temperatures tp2 and tp3 may be used to reduce the moisture further to a moisture content level w_F3. The moisture content level w_F3 represents the moisture content present in a composite.

The method may comprise providing a composition melt by melting the composition mixture. When processing a composition melt at temperatures above boiling point of water, which in normal atmospheric pressure is 100°C, the vaporization of the residual water contained in the organic natural fiber material may cause formation of porosity into the product material. The formation of porosity may further be due to inclusion of air or other surrounding gases during the expansion of water vapour when forming the composite. The porosity may appear, for example, in the form of gas bubbles or as voids between fiber surfaces and matrix material in a formed composite product. The effect of the desiccating process agent to the composition melt may be observed during the desiccating process agent addition period. In particular, the effect of the desiccating process agent to the composition melt may be observed during the composite melt feeding period between time points t3 and t4 and during the composite melt processing period between time points t4 and t5. Between time points t3 and t4, the temperature tp2 may be increased to a higher temperature tp3 in the manufacturing process. The composition melt may be in a feeding or processing unit, such as an extruder screw, having a fixed volume, the pressure p1 may increase to a pressure level p2. The pressure p2 during the composite melt processing period may vary. The pressure p2 during the composite melt processing period may be, for example, in the range of 0.1 to 1 100 2000 bars, or even higher, such as above 2000 bars, depending of the used mould design and other operating parameters. When the temperature TP(t) and pressure p(t) increase during the composite melt feeding period, the additional heat provided to the process may lead to further formation of free water molecules from hydrogen bound water molecules. Due to the increased pressure, the water molecules may be in a liquid state. As the desiccating process agent begins to bind the water molecules, the concentration of the water vapour may decrease to a level to a level w_V2, such as equal to or less than 0.1 wt.% or equal to or less than 0.01 wt.%, and the moisture bound in the desiccating process agent may reach a level w_des, representing the amount of residual water bound to desiccating process agent after addition of the desiccating process agent in the composite melt. The concentration of the desiccating process agent Cd_es may be selected such that the fiber moisture content level w_Fi is reduced to fiber moisture content level w_F3. The desiccating process agent may be added in an amount exceeding the stoichiometric concentration. The stoichiometric concentration refers to a concentration, wherein all moisture binding capacity of the desiccating process agent is in use. When an amount exceeding the stoichiometric concentration is used, a composite may comprise some desiccating process agent having moisture binding capacity. The method may comprise introducing desiccating process agent, such that the desiccating process agent concentration Cd_es may be equal to or less than 5 wt.%. In particular, when using chemically treated organic natural fiber material and the desiccating process agent is a mineral oxide, such as a calcium oxide, which may form a mineral hydroxide, the method may comprise introducing desiccating process agent in amounts equal to or less than 5 wt.%. The formation of hydroxide ions in general increases the pH levels, and may change the pH level and behaviour of the composite.

The method may comprise forming a composite comprising the chemically treated organic natural fiber material, the thermoplastic polymer material and the desiccating process agent. Forming the composite may be done a time point t5 at a temperature tp3 from the composition melt. The forming of the composite may comprise a process, wherein the composition melt is introduced in the direction of the melt flow, such as in an extrusion process or in a moulding process, for example a sheet extrusion, a co-extrusion, injection moulding or rotation moulding. The method may comprise arranging the pressure p2 to decrease to a pressure p1 lower than pressure p2. The decrease of pressure may take place in a period of a few seconds or even less. In an extrusion process the decrease of pressure takes place when the formed composite exits a die plate. In a moulding process the decrease of pressure may be controlled. The manufacturing process may comprise means of cooling the composite. For example, cooling by circulating water may be used to obtain a solid composite structure having a temperature tp1 . The effect of the desiccating process agent to the composition melt may be observed when a composite is formed of the composition melt. The moisture content w_F3 present in the composite and the water vapour content w_V2 may be maintained at a level similar to the composite melt processing period between time points t4 and t5. One of the effects of adding desiccating process agent is that the porosity of the material is reduced. Porosity may be problematic in particular in thin composite products, such as sheets or films comprising a maximum thickness D_max of a few millimetres. When the thickness of the composite is in the range of a few millimetres, even small defects in the structure of the composite product may cause reduced mechanical properties.

A method for obtaining a composite product by injection moulding The method may comprise providing a composition by injection moulding. Table 4 shows examples of injection moulding parameters for composite comprising thermoplastic polymer material and chemically treated organic natural fiber material. In the examples, the thermoplastic polymer material was polypropylene and the composite comprised 40 wt.% of cellulose fibers obtained from a chemically treated pulp. The injection moulding was performed by using a commercially available injection moulding machine Fanuc Roboshot a-100iA, where the screw diameter was 36 mm, the maximum shot volume was 140g and the shot volume used in each example was 26g. In the process, moisture content of cellulose fibre obtained from a chemically treated pulp was less than 0,1 %, delay time in screw in the range of 3 minutes and the melt flow index of the matrix material was 45 g/10min (230°C/2.16kg). Table 4. Examples of parameter values for injection moulding. Four examples TP1 , TP2, TP5 and TP6 represent samples with different provide differences in surface micro contour layer levels.

According to the examples, the injection speed may range from 5 to 400 mm/s, preferably 10 to 300 mm/s, most preferably 25 to 250 mm/s, such as 25, 100 or 220 mm/s. A mould surface temperature, which may be lower than the melting point Tm of the matrix material, may range from 25°C to 280°C. When introducing material into a workpiece, the mould temperature may during the introduction be high, such as in the range of 100°C to 280°C, to enable a higher injection velocity. After the composition melt has been introduced, the mould temperature may preferably be in the range of 25°C to 200°C, most preferably in the range of 30°C to 100°C, such as 30°C or 80°C, depending on the used thermoplastic polymer material. The effect of desiccating process agents in manufacturing process

Conventional chain extenders may be used to providing mechanical strength and melt strength to a structure. Melt strength may be advantageous during manufacturing and processing, for example enabling more stable processing. Chain extenders may enable recycling and re-use of composite. Examples of chain extenders are aromatic diols, aliphatic diols, carbon linear diols and carbon cyclic diols. According to an embodiment of the invention, a desiccating process agent may improve the composite mechanical properties such as strength, stiffness and elongation at break. Furthermore, a desiccating process agent may improve the melt behaviour of a composition melt, for example elongation at break. In particular, desiccating process agents acting through chemical binding, such as mineral oxides, may be used. When added in amounts of equal to or preferably less than 5 wt.%, such as described in this document, the adhesion between the desiccating process agent and the thermoplastic polymer material may be improved without decrease in mechanical properties. By improving the interface adhesion between the desiccating process agent and the matrix material, the strength and stiffness of the composite may be improved.

In particular, for thin extruded composite, comprising a maximum thickness of a few millimeters, such as in the range of 30 micrometers to ten millimeters, for example in the range of 30 micrometers to 120 micrometers, or in the range of 100 micrometers to 10000 micrometers, or in the range of 400 micrometers to 10000 micrometers, preferably in the range of 400 micrometers to 8000 micrometers, most preferably in the range of 400 micrometers to 6000 micrometers, the strength, stiffness and elongation at break may be improved by adding the desiccating process agent. When using injection moulding, a homogeneous mixing of the desiccating process agent should be provided for improving the interface adhesion and the strength, stiffness and elongation at break of the composite. Composite strength

According to an embodiment, in a thin extruded composite, when the amount of desiccating process agent is equal to or less than 5 wt.%, such as in the range of 3 - 5 wt.%, strength of the composite may be increased by

- at least 2%,

- in the range of 2% - 60%,

- preferably in the range of 20% - 60%,

- most preferably in the range of 30% - 50%

, in comparison to a composite material without the desiccating process agent.

According to an embodiment, in a thin extruded composite, when the amount of desiccating process agent is equal to or less than 3 wt.%, such as in the range of 1 - 3 wt.%, strength of the composite may be increased by

- at least 2%,

- in the range of 2% - 50%,

- preferably in the range of 10% - 40%,

- most preferably in the range of 15% - 40%,

, in comparison to a composite material without the desiccating process agent.

According to an embodiment, in a thin extruded composite, when the amount of desiccating process agent is equal to or less than 2 wt.%, such as in the range 0.5 - 2 wt.%, strength of the composite may be increased by

- at least 2%,

- in the range of 2% - 30%,

- preferably in the range of 4% - 20%,

- most preferably in the range of 6% - 15%.

, in comparison to a composite material without the desiccating process agent.

According to an embodiment, in a thin extruded composite, when the amount of desiccating process agent is equal to or less than 1 wt.%, such as in the range 0.3 - 1 wt.%, strength of the composite may be increased by - at least 2%,

- in the range of 2% - 20%,

- preferably in the range of 4% - 15%,

- most preferably in the range of 4% - 10%

, in comparison to a composite material without the desiccating process agent.

Preferably the strength of a composite having of desiccating process agent added to the composite melt or mixture may be at least 20 MPa or 30 MPa, more preferably at least 35 MPa or 40 MPa and most preferably at least 50 MPa or 60 MPa.

According to an embodiment, in a thin extruded composite, when the amount of desiccating process agent is equal to or less than 5 wt.%, such as in the range of 3 - 5 wt.%, strength of the composite may be

- at least 20 MPa,

- in the range of 40 MPa to 120 MPa

- preferably in the range of 50 MPa to 120 MPa

- most preferably in the range of 90 MPa to 120 MPa.

According to an embodiment, in a thin extruded composite, when the amount of desiccating process agent is equal to or less than 3 wt.%, such as in the range of 1 - 3 wt.%, strength of the composite may be

- at least 20 MPa,

- in the range of 30 MPa to 120 MPa

- preferably in the range of 40 MPa to 100 MPa

- most preferably in the range of 60 MPa to 90 MPa.

According to an embodiment, in a thin extruded composite, when the amount of desiccating process agent is equal to or less than 2 wt.%, such as in the range 0.5 - 2 wt.%, strength of the composite may be

- at least 20 MPa,

- in the range of 25 MPa to 120 MPa

- preferably in the range of 30 MPa to 70 MPa

- most preferably in the range of 40 MPa to 60 MPa. According to an embodiment, in a thin extruded composite, when the amount of desiccating process agent is equal to or less than 1 wt.%, such as in the range 0.3 - 1 wt.%, strength of the composite may be

- at least 20 MPa,

- in the range of 20 MPa to 120 MPa

- preferably in the range of 20 MPa to 60 MPa

- most preferably in the range of 20 MPa to 40 MPa.

Composite stiffness

According to an embodiment, in a thin extruded composite, when the amount of desiccating process agent is equal to or less than 5 wt.%, such as in the range of 3 - 5 wt.%, stiffness of the composite may be increased by

- at least 2%,

- in the range of 2% - 60%,

- preferably in the range of 20% - 60%,

- most preferably in the range of 20% - 50%

, in comparison to a composite material without the desiccating process agent.

According to an embodiment, in a thin extruded composite, when the amount of desiccating process agent is equal to or less than 3 wt.%, such as in the range of 1 - 3 wt.%, stiffness of the composite may be increased by

- at least 2%,

- in the range of 2% - 50%,

- preferably in the range of 15% - 50%,

- most preferably in the range of 15% - 40%,

, in comparison to a composite material without the desiccating process agent.

According to an embodiment, in a thin extruded composite, when the amount of desiccating process agent is equal to or less than 2 wt.%, such as in the range 0.5 - 2 wt.%, stiffness of the composite may be increased by

- at least 2%,

- in the range of 2% - 40%, - preferably in the range of 10% - 40%,

- most preferably in the range of 10% - 30%.

, in comparison to a composite material without the desiccating process agent.

According to an embodiment, in a thin extruded composite, when the amount of desiccating process agent is equal to or less than 1 wt.%, such as in the range 0.3 - 1 wt.%, stiffness of the composite may be increased by

- at least 2%,

- in the range of 2% - 20%,

- preferably in the range of 6% - 20%,

- most preferably in the range of 6% - 15%

, in comparison to a composite material without the desiccating process agent.

According to an embodiment, in a thin extruded composite, when the amount of desiccating process agent is equal to or less than 5 wt.%, such as in the range of 3 - 5 wt.%, stiffness of the composite may be

- at least 600 MPa,

- in the range of 2000 MPa to 12000 MPa

- preferably in the range of 4000 MPa to 12000 MPa

- most preferably in the range of 6000 MPa to 12000 MPa.

According to an embodiment, in a thin extruded composite, when the amount of desiccating process agent is equal to or less than 3 wt.%, such as in the range of 1 - 3 wt.%, stiffness of the composite may be

- at least 600 MPa,

- in the range of 1000 MPa to 12000 MPa

- preferably in the range of 1500 MPa to 8000 MPa

- most preferably in the range of 1500 MPa to 6000 MPa.

According to an embodiment, in a thin extruded composite, when the amount of desiccating process agent is equal to or less than 2 wt.%, such as in the range 0.5 - 2 wt.%, stiffness of the composite may be

- at least 600 MPa,

- in the range of 800 MPa to 6000 MPa - preferably in the range of 900 MPa to 4500 MPa

- most preferably in the range of 900 MPa to 1500 MPa.

According to an embodiment, in a thin extruded composite, when the amount of desiccating process agent is equal to or less than 1 wt.%, such as in the range 0.3 - 1 wt.%, stiffness of the composite may be

- at least 600 MPa,

- in the range of 600 MPa to 12000 MPa

- preferably in the range of 600 MPa to 1500 MPa

- most preferably in the range of 600 MPa to 900 MPa.

Composite strength and stiffness, in this context refers to flexural and/or tensile strength and stiffness. The addition of desiccating process agent may increase the flexural strength and stiffness. Further, the addition of desiccating process agent may increase the tensile strength and stiffness. The flexural strength and stiffness may be measured according standard ISO 178. The tensile strength and stiffness may be measured according to the general principles of ISO standard 527-1 , such as described in ISO standard 527-1 and 527-2.

Composite elongation at break

According to an embodiment, by addition of a desiccating process agent to a composition melt, when the amount of added desiccating process agent is equal to or less than 5 wt.%, such as in the range of 3 - 5 wt.%, elongation at break of the composite material may be increased by

- at least 2%,

- in the range of 2% - 60%,

- preferably in the range of 20% - 60%,

- most preferably in the range of 20% - 50%

, in comparison to a composite material without the desiccating process agent.

According to an embodiment, by addition of a desiccating process agent to a composition melt, when the amount of added desiccating process agent is equal to or less than 3 wt.%, such as in the range of 1 - 3 wt.%, elongation at break of the composite material may be increased by

- at least 2%,

- in the range of 2% - 50%,

- preferably in the range of 15% - 50%,

- most preferably in the range of 15% - 40%,

, in comparison to a composite material without the desiccating process agent. According to an embodiment, by addition of a desiccating process agent to a composition melt, when the amount of added desiccating process agent is equal to or less than 2 wt.%, such as in the range of 0.5 - 2 wt.%, elongation at break of the composite material may be increased by

- at least 2%,

- in the range of 2% - 40%,

- preferably in the range of 10% - 40%,

- most preferably in the range of 10% - 30%.

, in comparison to a composite material without the desiccating process agent.

According to an embodiment, by addition of a desiccating process agent to a composition melt, when the amount of added desiccating process agent is equal to or less than 1 wt.%, such as in the range 0.3 - 1 wt.%, elongation at break of the composite material may be increased by

- at least 2%,

- in the range of 2% - 20%,

- preferably in the range of 6% - 20%,

- most preferably in the range of 6% - 15%

, in comparison to a composite material without the desiccating process agent.

Composition melt elongation at break

The addition of a desiccating process agent to a composition melt may further have an effect on the elongation at break of the composition melt. The elongation at break of the composition melt is measured from a composition melt having a temperature higher than the glass transition temperature T_g and/or the melting point T_m of the matrix material.

According to an embodiment, by addition of a desiccating process agent to a composition melt, when the amount of added desiccating process agent is equal to or less than 5 wt.%, such as in the range of 3 - 5 wt.%, elongation at break of the composite melt may be increased by

- at least 2%,

- in the range of 2% - 60%,

- preferably in the range of 20% - 60%,

- most preferably in the range of 20% - 50%

, in comparison to a composite material without the desiccating process agent. According to an embodiment, by addition of a desiccating process agent to a composition melt, when the amount of added desiccating process agent is equal to or less than 3 wt.%, such as in the range of 1 - 3 wt.%, elongation at break of the composite melt may be increased by

- at least 2%,

- in the range of 2% - 50%,

- preferably in the range of 15% - 50%,

- most preferably in the range of 15% - 40%,

, in comparison to a composite material without the desiccating process agent.

According to an embodiment, by addition of a desiccating process agent to a composition melt, when the amount of added desiccating process agent is equal to or less than 2 wt.%, such as in the range of 0.5 - 2 wt.%, elongation at break of the composite melt may be increased by

- at least 2%,

- in the range of 2% - 40%,

- preferably in the range of 10% - 40%,

- most preferably in the range of 10% - 30%.

, in comparison to a composite material without the desiccating process agent. According to an embodiment, by addition of a desiccating process agent to a composition melt, when the amount of added desiccating process agent is equal to or less than 1 wt.%, such as in the range 0.3 - 1 wt.%, elongation at break of the composite melt may be increased by

- at least 2%,

- in the range of 2% - 20%,

- preferably in the range of 6% - 20%,

- most preferably in the range of 6% - 15%

, in comparison to a composite material without the desiccating process agent.

The elongation at break of a composite or a composition melt may be measured according to the general principles of ISO standard 527-1 , such as described in ISO standard 527-2 or the ASTM standard D638.

Thermoforming and elongation at break

Thermoforming may be used to reshape a formed composite article, such as a sheet or a film. Thermoforming may be used, for example, to manufacture containers such as cups, lids, trays, blisters, clamshells or other similar products for the food, medical, and general retail industries. Further, thermoforming may comprise the manufacture of enclosures for various devices, such as medical imaging and diagnostic equipment, mobile phones, electronic instruments, musical instruments or toys. In addition, the items may be covers such as vehicle door and dash panels, refrigerator liners, utility vehicle beds or plastic pallets to name a few. Thermoforming may comprise thin-, medium- or thick-gauge thermoforming, depending of the thickness of the composite product to be manufactured and of the thickness of the composite sheet to be formed.

Elongation at break in melt form is a beneficial property for a composite material, when the material is e.g. thermoformed. In thermoforming, a composite material is heated above glass transition point T_g and/or melting point T_m temperature of the matrix material and the material is reshaped to a different form by using vacuum and/or pressure. Thermoforming may be accomplished by using vacuum below the composite product, such as a sheet or a film.

Figure 8 illustrates, by way of an example, a method for providing a composite product M10 by thermoforming. In general, thermoforming may comprise the forming of composite product M10 of a heated composite CMP1 over a workpiece 200. In thermoforming, the composite product M10 may comprise a thickness D_max up to a few millimeters, such as in the range of 30 micrometers to 10 millimeters, for example in the range of 30 micrometers to 120 micrometers, or in the range of 100 micrometers to 10000 micrometers, or in the range of 400 micrometers to 10000 micrometers, preferably in the range of 400 micrometers to 7500 micrometers, most preferably in the range of 400 micrometers to 6000 micrometers. The shaping of the composite product M10 may be implemented by introducing a vacuum to a first surface 1 1 1 of a composite product M10 to hold the surface 1 1 1 of the product against the surface 501 of the workpiece 200. By providing heat to a second surface 1 12 of the composite product M10, the temperature of the composite CMP1 may be raised such that the composite CMP1 may be softened. The heat may be provided to both the first surface 1 1 1 and the second surface 1 12 to soften the composite CMP1 material. A convenient way to provide heat to both surfaces 1 1 1 , 1 12 of the product M10 may be, for example, by infrared radiation. After having provided heat to the first and/or second surface 1 1 1 , 1 12 of the composite product M10, the first and/or second surface 1 1 1 , 1 12 may be cooled by the workpiece 200 having a surface temperature lower than the surface temperatures of the composite product M10. The softened composite product M10 comprises conformability and the composite product M10 may be arranged to comprise a congruent curvature to form a complementary pair of the workpiece 200, as shown in Figure 8. The temperature of the workpiece 200 may be selected and controlled, such that when thermoplastic polymer materials are used, the workpiece surface temperature may be lower than the temperature of the product M10 to cool down the composite CMP1 material. After the product M10 has cooled down to a solid state, it may be removed from the workpiece 200. Alternatively, in thermoforming, the workpiece surface 201 may in the beginning of the manufacturing process comprise a surface temperature higher than the composite product temperature. Alternatively, or in addition the shaping of the composite CMP1 sheet may be implemented by introducing pressure on a first surface 1 1 1 and/or second surface 1 12 of a composite product M10, such as air pressure, to help the forming process.

For the person skilled in the art, it will be clear that modifications and variations of the products according to the present invention are perceivable. The drawings are schematic and for illustrative purposes. The method and the products are not limited solely to the above presented embodiments, but may be modified within the scope of the appended claims.

Claims

Claims:

1 . A composite (CMP1 ) comprising chemically treated organic natural fiber material (FIB1 ), thermoplastic polymer material (MTX1 ) and desiccating process agent (DES1 ), the composite (CMP1 ) having a moisture content of less than 2.0 wt.%, preferably less than 1 .5 wt.% or 1 .0 wt.%, most preferably less than 0.5 wt.% or 0.3 wt.% of the weight of the composite (CMP1 ).

2. The composite (CMP1 ) according to claim 1 , comprising a moisture content in the range of 0.05 wt.% to 2.0 wt.%, or in the range of 0.05 wt.% to

0.5 wt.% of the weight of the composite (CMP1 ).

3. The composite (CMP1 ) according to claim 1 or 2, wherein, the amount of desiccating process agent (DES1 ) in the composite (CMP1 ) is equal to or less than 5 wt.%, such as equal to or less than 2 wt.% of the weight of the composite (CMP1 ).

4. The composite (CMP1 ) according to any of the claims 1 to 3, wherein the amount of desiccating process agent (DES1 ) in the composite (CMP1 ) is in the range of 0.5 wt.% to 5 wt.%, such as in the range of 0.5 wt.% to 2 wt.% of the weight of the composite (CMP1 ).

5. The composite (CMP1 ) according to any of the claims 1 to 4, wherein the composite (CMP1 ) is a preliminary composite product (TMP1 ).

6. The composite (CMP1 ) according to claim 5, wherein preliminary composite product (TMP1 ) is an intermediate product, such as a spherical composite product or a granulate.

7. The composite (CMP1 ) according to any of the claims 1 to 6, formed by extrusion or moulding process.

8. The composite (CMP1 ) according to any of the claims 1 to 7, wherein the desiccating process agent (DES1 ) is an inorganic mineral compound, such as

- a mineral oxide or

- a mineral sulphate.

9. The composite (CMP1 ) according to any of the claims 1 to 8, wherein the desiccating process agent (DES1 ) is a mineral oxide, such as

- calcium oxide;

- magnesium oxide or

- zinc oxide.

10. The composite (CMP1 ) according to any of the claims 1 to 9, wherein the desiccating process agent (DES1 ) is

- calcium stearate;

- sodium stearate;

- zinc stearate;

- hydrotalcite;

- calcium lactate or lactylate;

- magnesium sulphate; or

- an aluminosilicate based compound such as a zeolite.

1 1 . The composite (CMP1 ) according to any of the claims 1 to 10, wherein the desiccating process agent (DES1 ) is calcium oxide.

12. The composite (CMP1 ) according to any of the claims 1 to 1 1 , wherein the chemically treated organic natural fiber material (FIB1 ) is wood pulp from a kraft process.

13. The composite (CMP1 ) according to any of the claims 1 to 12, having a lignin content of less than 10 wt.%, preferably less than 5 wt.%, more preferably less than 1 wt.%, most preferably less than 0.5 wt.%.

14. The composite (CMP1 ) according to any of the claims 1 to 13, wherein the chemically treated organic natural fiber material (FIB1 ) is in a flake form having a length, a width and a thickness.

15. The composite (CMP1 ) according to claim 14, wherein the width of the flake is 2-10 times larger than the thickness of the flake.

16. The composite (CMP1 ) according to claims 14 or 15, wherein the width of the flake is at least 2, or preferably at least 2.5, or more preferably at least 3 times the thickness of the flake.

17. The composite (CMP1 ) according to any of the claims 14 to 16, wherein the flake form has an aspect ratio relating to the ratio of the length to the thickness of 25-1500, or preferably 25-1000, or more preferably 25-500, or most preferably 25- 300.

18. The composite (CMP1 ) according to any of the claims 1 to 17, comprising chemically treated organic natural fiber material (FIB1 )

- equal to or more than 10 wt.%,

- such as equal to or more than 30 wt.%,

- such as equal to or more than 40 wt.%, of the weight of the formed composite (CMP1 ).

19. The composite (CMP1 ) according to any of the claims 1 to 18, wherein the formed composite (CMP1 ) comprises chemically treated organic natural fiber material (FIB1 )

- equal to or less than 70 wt.%

- such as equal to or less than 40 wt.%

- such as equal to or less than 30 wt.%, of the weight of the formed composite (CMP1 ).

20. The composite (CMP1 ) according to any of the claims 1 to 19, wherein the formed composite (CMP1 ) comprises chemically treated organic natural fiber material (FIB1 ) in the range of 10 to 70 wt.%, more preferably in the range of 20 to 50 wt.%.

21 . The composite (CMP1 ) according to any of the claims 1 to 20, wherein the formed composite (CMP1 ) comprises thermoplastic polymer (MTX1 )

- equal to or more than 30 wt.%,

- such as equal to or more than 50 wt.%,

- such as equal to or more than 60 wt.%,

- such as equal to or more than 70 wt.%.

22. The composite (CMP1 ) according to any of the claims 1 to 21 , wherein the formed composite (CMP1 ) comprises thermoplastic polymer (MTX1 ) - equal to or less than 90 wt.%,

- such as equal to or less than 70 wt.%,

- such as equal to or less than 60 wt.%,

- such as equal to or less than 50 wt.%.

23. The composite (CMP1 ) according to any of the claims 1 to 22, wherein the formed composite (CMP1 ) comprises thermoplastic polymer (MTX1 ) in the range of 90 to 30 wt.%, more preferably in the range of 80 to 50 wt.%.

24. The composite (CMP1 ) according to any of the claims 1 to 23, wherein the thermoplastic polymer (MTX1 ) is

- a polyolefin,

- such as a C2 to C₄ polyolefin,

- such as polyethylene or polypropylene.

25. The composite (CMP1 ) according to any of the claims 1 to 24, wherein the thermoplastic polymer (MTX1 ) is polystyrene, acrylonitrile butadiene styrene (ABS) or polyvinyl chloride (PVC).

26. The composite (CMP1 ) according to any of the claims 1 to 25, wherein the thermoplastic polymer (MTX1 ) comprises recycled polymer material.

27. The composite (CMP1 ) according to any of the claims 1 to 26, wherein the thermoplastic polymer (MTX1 ) comprises at least 50 wt.%, or preferably 70 wt.%, or more preferably 95 wt.%, or most preferably 100 wt.% of virgin polymer material.

28. A method for obtaining a composite (CMP1 ), which method comprises

- providing a composition mixture (MIXT1 ), which comprises chemically treated organic natural fiber material (FIB1 ) having a fiber moisture content (w_Fi ), and thermoplastic polymer material (MTX1 );

- providing a composition melt (MLT1 ) by melting the composition mixture (MIXT1 );

- introducing a desiccating process agent (DES1 ) having a moisture (VAP1 ) binding capacity; and

- forming a composite (CMP1 ) comprising the chemically treated organic natural fiber material (FIB1 ), the thermoplastic polymer material (MTX1 ) and the desiccating process agent (DES1 ).

29. The method according to claim 28, further comprising

- melting a preliminary mixture (MIXT2) comprising chemically treated organic natural fiber material (FIB1 ) and thermoplastic polymer material (MTX1 );

- forming a preliminary composite product (TMP1 ), such as a spherical, cylindrical or granular intermediate product; and

- providing the composition mixture (MIXT1 ) by mixing the preliminary composite product (TMP1 ).

30. The method according to claim 28, wherein the composition mixture (MIXT1 ) is provided by mixing the chemically treated organic natural fiber material (FIB1 ) and the thermoplastic polymer material (MTX1 ).

31 . The method according to any of the claims 28 to 30, further comprising

- arranging at least partial evaporation of moisture (VAP1 ) from the composition mixture (MIXT1 ) or the composition melt (MLT1 ) by heating; or

- heating the composition mixture (MIXT1 ) or the composition melt (MLT1 ) to a temperature (tp2) of at least 100°C or higher; or

- heating the composition melt (MLT1 ) to a temperature (tp3) of at least 140°C or higher, such as in the range of 140°C to 220°C

, in order to reduce the fiber moisture content (w_Fi ) before introducing the desiccating process agent (DES1 ).

32. The method according to any of the claims 28 to 31 , further comprising

- introducing the desiccating process agent (DES1 ) before melting the composition mixture (MIXT1 ), such as when providing the composition mixture (MIXT1 ); or

- introducing the desiccating process agent (DES1 ) when melting the composition mixture (MIXT1 ); or

- introducing the desiccating process agent (DES1 ) after melting the composition mixture (MIXT1 ) and before forming the composite (CMP1 ).

33. The method according to any of the claims 28 to 32, wherein

- the amount of desiccating process agent (DES1 ) added is equal to or less than 5 wt.%, such as less than 2wt.% or less than 1 wt.% of the weight of the formed composite (CMP1 ).

34. The method according to claim 29, wherein the preliminary composite product (TMP1 ) has a moisture content of less than 2.0 wt.%, preferably less than 1 .5 wt.% or 1 .0 wt.%, most preferably less than 0.5 wt.% or 0.3 wt.% of the weight of the preliminary composite product (TMP1 ).

35. The method according to any of the claims 28 to 34, further comprising

- providing chemically treated organic natural fiber material (FIB1 ), wherein the chemically treated organic natural fiber material (FIB1 ) has a fiber moisture content (w_Fi ) equal to or the less than 2.0 wt.%, such as equal to or less than 0.5 wt.% or equal to or less than 0.3 wt.%, for example in the range of 0.05 wt.% to 2.0 wt.%, or in the range of 0.05 wt.% to 0.5 wt.% of the weight of the composition mixture (MIXT1 ), when providing the composition mixture (MIXT1 ).

36. The method according to any of the claims 28 to 35, wherein forming the composite (CMP1 ) comprises

- a thermoforming process, wherein the composite (CMP1 ) is at least partially melted; or

- a process, wherein the composition melt (MLT1 ) is introduced in the direction of the melt flow (DIRMD), such as an extrusion process or a moulding process, for example a sheet extrusion, a co-extrusion, injection moulding or rotation moulding.

37. The method according to any of the claims 28 to 36, wherein the desiccating process agent (DES1 ) is an inorganic mineral compound, such as

- a mineral oxide or

- a mineral sulphate

38. The method according to any of the claims 28 to 37, wherein the desiccating process agent (DES1 ) is a mineral oxide, such as

- calcium oxide;

- magnesium oxide or

- zinc oxide

39. The method according to any of the claims 28 to 38, wherein the desiccating process agent (DES1 ) is

- calcium stearate;

- sodium stearate;

- zinc stearate;

- hydrotalcite;

- calcium lactate or lactylate;

- magnesium sulphate; or

- an aluminosilicate based compound such as a zeolite

40. The method according to any of the claims 28 to 39, wherein the desiccating process agent (DES1 ) is calcium oxide.

41 . The method according to any of the claims 28 to 40, wherein the chemically treated organic natural fiber material (FIB1 ) is wood pulp from a kraft process.

42. The method according to any of the claims 28 to 41 , wherein the lignin content of the chemically treated organic natural fiber material (FIB1 ) is less than 10 wt.%, or preferably less than 5 wt.%, or more preferably less than 1 wt.%, or most preferably less than 0.5 wt.% of the weight of the organic natural fiber material (FIB1 ).

43. The method according to any of the claims 28 to 42, wherein the chemically treated organic natural fiber material (FIB1 ) is in a flake form having a length, a width and a thickness.

44. The method according to claim 43, wherein the width of the flake is 2-10 times larger than the thickness of the flake.

45. The method according to claim 43 or 44, wherein the width of the flake is at least 2, or preferably at least 2.5, or more preferably at least 3 times the thickness of the flake.

46. The method according to any of the claims 43 to 45, wherein the flake form has an aspect ratio relating to the ratio of the length to the thickness of 25-1500, or preferably 25-1000, or more preferably 25-500, or most preferably 25- 300.

47. The method according to any of the claims 28 to 46, wherein the formed composite (CMP1 ) comprises chemically treated organic natural fiber material (FIB1 )

- equal to or more than 10 wt.%,

- such as equal to or more than 30 wt.%,

48. The method according to any of the claims 28 to 47, wherein the formed composite (CMP1 ) comprises chemically treated organic natural fiber material (FIB1 )

- equal to or less than 70 wt.%

- such as equal to or less than 40 wt.%

49. The method according to any of the claims 28 to 48, wherein the formed composite (CMP1 ) comprises chemically treated organic natural fiber material (FIB1 ) in the range of 10 to 70 wt.%, more preferably in the range of 20 to 50 wt.%.

50. The method according to any of the claims 28 to 49, wherein the formed composite (CMP1 ) comprises thermoplastic polymer (MTX1 )

- equal to or more than 30 wt.%,

- such as equal to or more than 50 wt.%,

- such as equal to or more than 60 wt.%,

- such as equal to or more than 70 wt.%.

51 . The method according to any of the claims 28 to 50, wherein the formed composite (CMP1 ) comprises thermoplastic polymer (MTX1 )

- equal to or less than 90 wt.%,

- such as equal to or less than 70 wt.%,

- such as equal to or less than 60 wt.%,

- such as equal to or less than 50 wt.%.

52. The method according to any of the claims 28 to 51 , wherein the formed composite (CMP1 ) comprises thermoplastic polymer (MTX1 ) in the range of 90 to 30 wt.%, more preferably in the range of 80 to 50 wt.%.

53. The method according to any of the claims 28 to 52, wherein the thermoplastic polymer (MTX1 ) is

- a polyolefin,

- preferably a C2 to C₄ polyolefin,

- preferably polyethylene or polypropylene.

54. The method according to any of the claims 28 to 53, wherein the thermoplastic polymer (MTX1 ) is polystyrene, acrylonitrile butadiene styrene (ABS) or polyvinyl chloride (PVC).

55. The method according to any of the claims 28 to 54, wherein the thermoplastic polymer (MTX1 ) comprises recycled polymer material.

56. The method according to any of the claims 28 to 55, wherein the thermoplastic polymer (MTX1 ) comprises at least 50 wt.%, or preferably 70 wt.%, or more preferably 95 wt.%, or most preferably 100 wt.% of virgin polymer material.

57. A composite (CMP1 ) obtainable according to any of the claims 28 to 56.

58. A product comprising composite (CMP1 ) according to any of the claims 1 to 27.

59. Use of desiccating process agent according to any of the claims 28 to 56 to reduce the fiber moisture content (w_Fi ) of chemically treated organic natural fiber material (FIB1 ) when forming a composite (CMP1 ).

60. Use of desiccating process agent according to any of the claims 28 to 56 in a sheet extrusion process to obtain composite (CMP1 ).

61 . Use of calcium oxide as desiccating process agent according to any of the claims 28 to 56 to obtain composite (CMP1 ).

62. Use of the composite (CMP1 ) according to any of the claims 1 to 27 in a thermoforming process to obtain a product comprising the composite (CMP1 ).

63. A product comprising composite (CMP1 ) obtainable according to any of the claims 28 to 56.