阅读说明：本技术 用于制备生物基复合材料的加工木质纤维素纤维的混合物的方法 (Method for processing a mixture of lignocellulosic fibres for the preparation of a bio-based composite material ) 是由 J·G·范吉尔斯特 于 2018-04-03 设计创作，主要内容包括：本发明涉及一种加工木质纤维素纤维的混合物的方法,例如加工芒草纤维或高粱纤维的混合物的方法,所述方法用于制备生物基复合材料,该方法包括以下步骤：收获木质纤维素作物并加工所收获的木质纤维素作物,获得木质纤维素纤维的原料混合物,将木质纤维素纤维的原料混合物分离为第一组份(f1)和第二组份(f2),例如通过筛分或研磨进行分离,所述第一组份(f1)包含纤维尺寸约<s1且具有第一物理/化学特性的纤维的混合物,所述第二组份(f2)包含纤维尺寸约>s1且具有第二物理/化学特性的纤维的混合物,所述第二物理/化学特性与所述第一物理/化学特性不同,将所述第一组份(f1)的纤维或所述第二组份(f2)的纤维与粘合剂(3)混合,使粘合剂硬化,获得所述生物基复合材料。(The present invention relates to a method of processing a mixture of lignocellulosic fibres, for example a mixture of miscanthus fibres or sorghum fibres, for the preparation of a bio-based composite material, the method comprising the steps of: harvesting a lignocellulosic crop and processing the harvested lignocellulosic crop, obtaining a raw mixture of lignocellulosic fibres, separating the raw mixture of lignocellulosic fibres into a first component (f1) and a second component (f2), for example by sieving or grinding, the first component (f1) comprising a mixture of fibres having a fibre size of about < s1 and having a first physical/chemical property, the second component (f2) comprising a mixture of fibres having a fibre size of about > s1 and having a second physical/chemical property, the second physical/chemical property being different from the first physical/chemical property, mixing the fibres of the first component (f1) or the fibres of the second component (f2) with a binder (3), hardening the binder, obtaining the bio-based composite.)

1. A method (100) of processing a mixture of lignocellulosic fibres, such as a mixture of miscanthus fibres or sorghum fibres, for the preparation of a bio-based composite (1), the method comprising the steps of:

-harvesting (101) a lignocellulosic crop and processing the harvested lignocellulosic crop to obtain a raw mixture of lignocellulosic fibres (2),

-separating (102) a raw mixture of lignocellulosic fibres into a first fraction (f1) and a second fraction (f2), said separating (102) being carried out, for example, by sieving or grinding, said first fraction (f1) comprising fibres of a size of about the fibre size_<s1 and having a first physical/chemical characteristic, the second component (f2) comprising fibers having a fiber size of about_>s1 and having a second physical/chemical characteristic different from the first physical/chemical characteristic,

-mixing (201) the fibers of the first component (f1) or the fibers of the second component (f2) with a binder (3),

-curing (202) the binder to obtain the bio-based composite.

2. Method according to claim 1, wherein the binder is a mortar, the fibres have a fibre size below 1.5mm and the content of fibres is in the range of 7 to 20 wt% to obtain a 3D printable concrete mixture, and the mortar is preferably based on MgO/hydrous MgCl₂A mortar system.

3. The method according to claim 1, wherein the binder is a mortar, at least 50% by weight of the fibres have a fibre size between 2 and 8mm and the content of fibres is in the range between 5 and 13% by volume to obtain a concrete mixture.

4. The method of claim 3, further comprising the steps of:

a) weighing material

b) Dry blending the powders (cement and fillers other than sand)

c) Adding sand and dry mixing the sand with the powder

d) Adding water in an amount of 75% of the total amount of water and mixing the materials uniformly

e) Optionally allowing the mixture to stand for about 1 minute

f) Add superplasticizer + remaining 25% water and continue slow mixing

g) Adding dry Chinese silvergrass fiber and continuously slowly mixing

h) Additional water (2.5 g water per 1gr fiber) was added and slow mixing continued

Optionally increasing the mixing speed to separate the agglomerated fibers to obtain a concrete mixture containing miscanthus.

5. A method according to claim 3 or 4, wherein the bio-based concrete mixture comprises 0.01 to 1 wt% of a superplasticizer, preferably a polycarboxylate ether plasticizer.

6. Method according to any one of the preceding claims, wherein the lignocellulosic crop is a dry crop and the raw mixture of lignocellulosic fibres comprises at least 80 wt%, preferably at least 90 wt% or at least 91 wt% dry fibres and 5-20 wt% water.

7. A process according to claim 1, wherein the first fraction is further separated to obtain a first further fraction comprising fibres having a length of 0.3-0.5 mm.

8. A process according to claim 7, wherein the first fraction is further separated to obtain a first further fraction comprising fibres having a length of about 0.3-0.4 mm.

9. A process according to claim 7 or 8, wherein the first fraction is further separated to obtain a first further fraction comprising fibres having a length of about 0.325-0.375 mm.

10. A process according to claim 7, 8 or 9, wherein the first fraction is further separated to obtain a first further fraction comprising fibres having a length of about 0.35 mm.

11. The method according to any one of the preceding claims, comprising the steps of:

-separating (103) the second fraction (f2) into a third fraction (f3) and a fourth fraction (f4), the separation (103) being performed, for example, by sieving or grinding, the third fraction (f3) comprising a mixture of fibers having a fiber size of about > s1 and about < s2, the fourth fraction (f4) comprising a mixture of fibers having a fiber size of about > s 2.

12. A method (200) of producing a bio-based composite using a first component, a second component, a third component and/or a fourth component according to any of the preceding claims, the method further comprising the steps of:

mixing (201) the fibres of the first component, the fibres of the second component, the fibres of the third component and/or the fibres of the fourth component with a binder (3), wherein the ratio of mixing is determined according to the desired characteristics of the bio-based composite to be produced,

curing (202) the binder to obtain the bio-based composite.

13. The method of claim 1 or any of claims 6-12, further comprising the steps of:

pressing (204) the fibres of the first component, the fibres of the second component, the fibres of the third component and/or the fibres of the fourth component into pellets (6) with the addition of an adhesive (5), the adhesive (5) being for example maltodextrin,

-mixing (201) said pellets containing fibres of a first component, fibres of a second component, fibres of a third component and/or fibres of a fourth component with said binder and allowing said binder to solidify to obtain said bio-based composite, and

-processing (203) the bio-based composite material into particles.

14. The method of claim 1 or any of claims 6-13, further comprising the steps of:

-compressing (204) the granules (4) into a tablet (7).

15. The method of claim 1 or any one of claims 6 to 14, wherein the method further comprises the steps of:

-processing the bio-based composite, the granules or the sheets into a product, for example a product for absorbing moisture, such as a food package or a diaper.

16. A method according to any preceding claim, wherein the first component comprises at least 70%, more preferably at least 80%, even more preferably at least 90%, most preferably about 100% of the fibre blend to be mixed with the binder.

17. The method according to any one of the preceding claims, wherein when the bio-based composite material is a bio-based concrete mix, the method further comprises the steps of:

prior to curing the mortar, a fluid mortar/fiber mixture was printed in the desired shape using a 3D printer.

18. Method according to any of the preceding claims, wherein the processing temperature for thermoforming is about 110 ℃ > 130 ℃, preferably about 120 ℃ when the particles or the sheet are processed by thermoforming into a product, such as into a product for absorbing moisture, such as into a food package or a diaper.

19. A granular or bio-based concrete mixture obtained by the method of any one of the preceding claims.

20. A product obtained according to the method of claim 15 or claim 17, such as a product for absorbing moisture, such as a food package or a diaper, or a 3D printed concrete structure.

21. The product of claim 20, wherein the product is a consumer product.

22. The product of claim 20 or 21, wherein the product is a product for absorbing moisture.

23. The product of claim 20, 21 or 22, wherein the product is a food package or a diaper.

24. The product of claim 20, 21 or 22, wherein the product is cat litter, a light cover, a tray or a bottle.

25. A bio-based concrete mixture comprising from 5 to 13 volume% fibres, wherein at least 50 wt% of the fibres have a fibre size between 2 and 8 mm.

26. The bio-based concrete mixture according to claim 25, wherein at least 70 weight percent of said fibers have a fiber size between 2mm and 8 mm.

27. The bio-based concrete mixture according to claim 25 or 26, wherein the fibers are miscanthus fibers.

28. The bio-based concrete mixture according to any one of claims 25 to 27, wherein the mixture contains 0.01 to 1 wt% (relative to the total weight of the concrete mixture) of a superplasticizer.

29. The bio-based concrete mixture according to any one of claims 25 to 28, wherein the bio-based concrete mixture comprises a superplasticizer comprising a polycarboxylic ether plasticizer.

30. A 3D printable concrete mixture comprising 7 to 20 wt% fibres having a particle size of less than 1.5 mm.

31. The 3D printable concrete mixture of claim 30, wherein the concrete mixture contains 10 to 15 wt% of miscanthus fibers having a fiber size of less than 1.5 mm.

32. The 3D printable concrete mixture according to claim 30 or 31, wherein the mixture is based on MgO/aqueous MgCl₂A mortar system.

Technical Field

The present invention relates to a method of processing a mixture of lignocellulosic fibres, such as a mixture of miscanthus (miscanthus) fibres or sorghum fibres (sorghum fibres), for the preparation of a bio-based composite material, the method comprising the steps of:

-harvesting a lignocellulosic crop and processing the harvested lignocellulosic crop to obtain a feedstock mixture of lignocellulosic fibres. The invention also relates to products containing lignocellulosic fibres, such as bio-based composites and bio-based concrete.

Background

Such methods are well known in the art. The prior art discloses numerous methods for obtaining mixtures of fiber raw materials and subsequent production of bio-based composites from these fibers.

For example, international (PCT) patent publication WO 2010139056 relates to a method of manufacturing a bioplastic material and an article obtained by molding the inventive plastic material.

Chinese patent publication CN 104327525 discloses a biodegradable plastic comprising grass meal (e.g. miscanthus) as a raw material. The biodegradable plastic comprises 30-60% of grass meal, 20-45% of PE, 3-10% of modifier, 3-10% of adhesive and 3-5% of bleaching agent. Grass meal is used as a base stock and blended with PE, modifiers, binders and bleaches to produce biodegradable plastics.

German patent publication DE 4336627 discloses a composite material, i.e. a thermoplastic material matrix and a fibrous material, such as reed (reed) or rush. For best enhancement, the preferred reed type is "miscanthus sinensis" with a size/diameter ratio of 10. The reed strip can be embedded in the plastic matrix unidirectionally or bidirectionally.

European patent publication EP 0830424 a1 discloses a plastic-based composite product which is at least partly composed of a plastic which consists essentially of particles uniformly embedded therein, the particles having a tensile strength in at least one main direction. The particles include: small particles, in particular plates or fibers having random orientation and a size of 0.2-2 mm; and, predominantly oriented large particles, e.g., 80-95% of the particles have a major direction in the selected major direction of the product and a dimension in the major direction of the particles of about 2-6 mm.

European patent publication EP 2647758 a1 describes a process for the industrial production of fibre-reinforced composites from intensive agricultural waste of musa (musa genus), banana, plantain, abaca and the like. These methods describe a process for extracting fibers from a dried pseudostem (pseudo-stem's) lignocellulose substrate and using the lignocellulose substrate in turn to produce a reactive gluing resin that can encapsulate the obtained fibers to produce a fiber-reinforced composite material that can be biodegraded by microorganisms.

International (PCT) patent publication WO 2006048332 a1 relates to an extrudable compound, an extrusion method and an extruded product comprising a polymer, cellulosic fibers and a lubricant selected from at least one of the group consisting of ethoxylated hydantoin esters (esters of ethoxylated hydantoins), ethoxylated sorbitol esters (esters of ethoxylated sorbosols) or ethoxylated sorbitan esters, or N, N' -bisalkanoylethylenediamines (ns) containing 8 to 14 carbon atoms in each alkyl group. The extruded product made according to the invention simulates a conventional wood based product.

However, in practice, the quality and properties of the final fiber mixture in the matrix of the final product appear to be unpredictable, resulting in unpredictable properties in the final product. Furthermore, due to the non-optimized use of available fiber mixtures: the fibers may exhibit physical/chemical characteristics that are actually detrimental to the final product, such as high moisture absorption when low moisture absorption is actually desired, and thus the final product is less environmentally friendly than desired. Sometimes, the quality of the end product is low due to the low quality of the fibre mixture used, resulting in the end product being discarded completely.

Disclosure of Invention

Object of the Invention

It is an object of the present invention to provide a method for processing a mixture of lignocellulosic fibres for the preparation of a bio-based composite, wherein the quality and properties of the mixture of fibres eventually present in the matrix of the final product are more predictable, resulting in a more predictable performance of the final composite product.

It is another object of the present invention to produce a bio-based composite material with improved composting capabilities.

Another object is to produce a concrete comprising lignocellulosic fibres having improved properties.

It is a further object of the present invention to provide a method for processing a mixture of lignocellulosic fibres for the preparation of bio-based composites, wherein an optimal utilization is achieved by the amount of fibre mixture available.

Drawings

The invention will be explained hereinafter by means of exemplary embodiments of the method according to the invention and with reference to the drawings. Wherein:

fig. 1 schematically illustrates a method of processing a mixture of lignocellulosic fibers for making a bio-based composite.

Fig. 2 schematically illustrates a method of processing a mixture of lignocellulosic fibers for making a bio-based composite material, wherein the bio-based composite is processed into particles.

Fig. 3 schematically illustrates a method of pressing a mixture of fibers into pellets and mixing the pellets with a binder.

FIG. 4 schematically illustrates a method of processing granules into tablets; and

fig. 5 shows a graph depicting bulk density and moisture content of several fiber component samples.

Description of the reference numerals

1. Bio-based composite material

2. Raw material mixture of lignocellulose (miscanthus) fiber

3. Adhesive agent

4. Granules

5. Adhesive agent

6. Granular material

7. Sheet

100. Method for processing a mixture of lignocellulosic fibres for the preparation of a bio-based composite material

101. Harvesting step

102. Separation step (1)

103. Separation step (2)

200. Method for producing bio-based composite materials

201. Mixing step

202. Curing step

203. Step of processing into granules

204. Pressing into granules

205. Step of tableting

Detailed Description

Fig. 1 schematically illustrates a method 100 of processing a mixture of lignocellulosic fibres, such as a mixture of miscanthus fibres or sorghum fibres, for producing a bio-based composite material 1, the method 100 comprising the steps of:

-harvesting 101 a lignocellulosic crop and processing the harvested lignocellulosic crop to obtain a raw mixture of lignocellulosic fibres 2. According to the invention, the method 11 is characterized in that

-separating 102 the raw mixture of lignocellulose fibers into a first component f1 and a second component f2, for example by sieving or grinding, the first component f1 comprising a mixture of fibers having a fiber size of about < s1 and having a first physical/chemical property, the second component f2 comprising a mixture of fibers having a fiber size of about > s1 and having a second physical/chemical property, the second physical/chemical property being different from the first physical/chemical property. Preferably s1 is 1.0-3.0mm, more preferably 1.5-2.5mm, for example 2 mm. Preferably, the harvesting step comprises cutting the fibres. The separation step preferably comprises (in a continuous manner) one or more subsequent sieving and grinding steps.

To characterize the moisture content, e.g., as a (physical property), of the first component f1 and the second component f2, the individual components f1, f2 (i.e., their samples) may be heated (e.g., overnight) to a temperature of 90-110 ℃, e.g., about 105 ℃, to determine their respective moisture content. Thus, by testing different values of s1, an optimum value of s1 can be determined to provide a certain desired moisture content in first component f1 or second component f 2.

The density of each component f1, f2 can be determined using one of the above (dried) samples and a helium pycnometer. Thus, similarly, by testing different values of s1, the optimum value of s1 can be determined so that first component f1 or second component f2 has a certain desired density.

For example, a specific gravity balance (hydraulic balance) may be used to determine the water absorption of each individual size component f1, f2 as an indicator of the total amount of water absorbable of the bio-based composite material 1 or the final product comprising the components f1, f 2. When bio-based composite 1 is a bio-based concrete mix comprising concrete or mortar, isothermal calorimetry may be used to examine the effect of the fibers of first component f1 and second component f2 on cement hydration in a relatively small (e.g., 10 ml) sample. The components f1, f2 can be ground, for example, in a mill such as a ball mill, and then mixed with the cement. The heat generated during hydration can be measured and compared to a "neat" cement slurry. Lignocellulosic fibres are boiled in water to leach organic material from the fibres. Water was then mixed with the cement and its effect on hydration was measured. After preliminary evaluation by isothermal calorimetry, a larger volume/lignocellulose mixture can be prepared in an insulated mold and the temperature measured during hydration. The lignocellulose will be mixed "as is", giving less accurate but more realistic information about the effect of lignocellulose on cement hydration.

Based on the above measurements/characteristics, in case a bio-based concrete like bio-based composite 1 is to be obtained, a plurality of formulations with different ratios of lignocellulose/cement/water can be made and tested for physical/chemical properties (e.g. mechanical properties, density, rheological properties).

The pretreatment method of the lignocellulosic fibres, for example immersion in water or a salt solution, can be tested and used in cement.

Preferably, the above steps are repeated on lignocelluloses harvested under different conditions of year, season, location, soil type, etc. to obtain an index of "natural" variation of physical/chemical properties.

As shown in fig. 1, the second component f2 can be further separated 103 into a third component f3 and a fourth component f4, for example by sieving or grinding, the third component f3 comprising a mixture of fibers having a fiber size of about > s1 and about < s2, and the fourth component f4 comprising a mixture of fibers having a fiber size of about > s 2. Preferably s2 is 3.0-5.0mm, more preferably 3.5-4.5mm, for example 4 mm.

Fig. 2 schematically shows a method 200 for producing a bio-matrix composite 1 by using a first component f1, a second component f2, a third component f3 and/or a fourth component f4, the method further comprising the steps of:

mixing 201 the fibers of the first component f1, the second component f2, the third component f3 and/or the fourth component f4 with the binder 3, wherein the mixing ratio is determined based on the desired properties of the bio-based composite 1 to be produced,

-curing 202 the binder 3 to obtain the bio-based composite 1.

Further steps of the method 200 may include the steps of:

processing 203 the bio-based composite material into particles 4.

The method 200 may comprise the further steps of:

-pressing 204 the fibres of the first component f1, the fibres of the second component f2, the fibres of the third component f3 and/or the fibres of the fourth component f4 into pellets 6 with the addition of a binder 5, such as maltodextrin.

-mixing 201 pellets 6 comprising fibres of the first component f1, fibres of the second component f2, fibres of the third component f3 and/or fibres of the fourth component f4 with a binder 3 and curing the binder 3 to obtain a bio-based composite 1, and

-processing 203 the bio-based composite material 1 into particles 4.

As previously mentioned, preferably, the binder 3 is plastic and the mixing of the pellets 6 with the binder 3 is performed by a plastic extruder. More preferably, s1 is selected to be about 0.5mm, and then pellets 6 are made using first component f1 of fibers having a size of less than 0.5 mm. Such pellets 6 are easy to produce by pressing, easy to mix with the binder 3 and easy to process into granules 4.

Incidentally, at the time of pressing (i.e., during pressing of the pellets 6), the maltodextrin advantageously becomes warm and therefore sticky due to friction in the pressing.

As shown in fig. 4, the method 200 may further include:

compressing 204 the granulate 4 into a tablet 7.

Finally, the method 200 comprises the following further steps:

processing the bio-based composite material 1, the granules 4 or the sheet 7 into a product, for example a product intended to absorb moisture, such as a food package or a diaper. Other (consumer) products are of course also conceivable, such as vases, lampshades, cat litter, (packaging) trays, etc. Preferably, when the diaper is produced, the bio-based composite 1 is incorporated into a pad or similar support/container, which acts as a desiccant (much like silica gel). Therefore, diaper pads are not made by thermoforming, extrusion, etc., unlike several other (consumer) products, such as crockery (pottery), trays, bottles, etc. Preferably, the pad or similar support/container contains one or more layers comprising miscanthus fibers (as a film).

The applicant has also found that the production of a sheet 7 having a plurality of layers (for example 1, 2, 3, 4, 5 layers but preferably 3 layers) makes it possible to further optimize the mechanical and/or chemical properties of the final product. Preferably, the layers are subsequently applied in an alternating manner, for example a-B-a (when 3 layers are used), wherein the outer layers have mechanical or chemical properties a and the intermediate layers have mechanical or chemical properties B. For example, the intermediate layer (particularly when an odd number of layers are used) may be reinforced with other types of fibers, such as jute or scrim. Preferably, layer a does not contain miscanthus and is made from a biocompatible resin (e.g., PLA), and layer B contains miscanthus fibers.

Preferably, especially when producing diapers or packaging products, the sheet 7 is processed into a product using thermoforming or thermoforming processes. More preferably, a thermoforming process is used wherein the processing temperature is about 110-. Applicants have advantageously found that when sheet 7 comprises predominantly (i.e., > 50%, preferably > 70%, more preferably > 80% or even > 90%) fibers having a fiber size of about 0.3-0.5mm (where s1 is about 0.3 and s2 is about 0.5mm), preferably about 0.3-0.4mm, more preferably about 0.325-0.375mm, for example about 0.35mm, the temperature of the process (oven) can be reduced compared to the typical temperature of about 180 ℃. This saves a lot of energy during the thermoforming process. Applicants have found that a 20-30% energy savings is feasible, improving and enhancing the durability of the product.

Applicants have also found from practice that the first step separation component comprises fibers having a fiber size of from about 0.3 mm to about 0.5mm, preferably from about 0.3 mm to about 0.4mm, more preferably from about 0.325 mm to about 0.375mm, for example about 0.35mm, as described above, which reduces friction during extrusion of the pellets and tablets. At the same time, such fiber size surprisingly results in very good moisture absorption and mechanical properties in the final (consumer) product.

In one embodiment, at least 70%, more preferably at least 80%, even more preferably at least 90%, most preferably about 100% of the fiber mixture 2 to be mixed with the binder 3 consists of the first component f 1.

When cutting the edges of the sheet 7, a circular knife (i.e., a "pizza knife") is preferably used to obtain a clean edge, rather than, for example, a Stanley (Stanley) knife, before the sheet 7 is rolled into a roll or onto a roll.

Preferably, the fibers are blended with natural polymers (rather than the relatively unnatural polymers, such as PE and PP) to improve the compostability of the product, thereby reducing the burden on the environment.

The bio-based composite material 1 may be a bio-based concrete mixture and the binder 3 may be a mortar.

Optionally, in the fibre mixture 2 to be mixed with the mortar, at least 70%, more preferably at least 80%, even more preferably at least 90%, most preferably about 100% is constituted by the third component f 3.

The method may further comprise the steps of:

-printing the mortar/fibre mixture in the desired shape using a 3D printer before the mortar is cured.

It should be clear that the above description is intended to illustrate the operation of a preferred embodiment of the invention, and not to reduce the scope of protection of the invention. Starting from the above description, numerous embodiments are possible for a person skilled in the art within the scope of the inventive concept and protection of the present invention.