DE212024000101U1 - wood fiberboard - Google Patents

Abstract

Wood fibreboard with a solid content of wood fibres bonded with a urea-formaldehyde resin, characterized in that the wood fibreboard contains coffee grounds and that the solid content of coffee grounds is at most 80% by weight.

Description

The invention relates to a wood fiberboard made with coffee grounds. Wood has become a precious resource worldwide, and especially in Europe, due to climate change, as many trees are severely threatened by heat and drought. At the same time, pests are spreading extremely rapidly, making deforestation necessary, but subsequent reforestation takes decades. Wood should also be used as sparingly as possible with regard to its _carbon footprint.

On the other hand, wood fiberboard has an extremely broad range of applications, with diverse requirements regarding technical properties, especially mechanical strength. Examples include the use of wood fiberboard in the construction and furniture industries, the funeral industry, and the automotive industry.

In order to save resources, Poo Chow suggested in his 1976 publication “ The Use of Crop Residues for Boardmaking,” Environmental Conservation, Vol. 3, No.1, Spring 1976, pages 59-62 The idea was to mix typical US agricultural waste products, such as peanut shells, with another waste product, including coffee grounds, bond them together with a urea resin (UF glue), and press them into a board. In a series of experiments, maple shavings from a furniture factory were also added, producing a particle board. However, due to its low flexural elasticity, this board is unsuitable for use as a load-bearing element in the construction industry.

From the WO-A2-2018/078391 A process is known in which agricultural waste products, namely straw fibers, are pressed into sheets. Another waste product, namely coffee grounds, is used as an additive. Furthermore, the teaching of the WO-A2-2018/078391 The objective is to avoid formaldehyde-containing adhesive resins and instead use pMDI (polymeric diphenylmethane diisocyanate) to bond the raw materials. However, pMDI is highly reactive and requires the use of a special, closed production facility because the isocyanate contained in pMDI adheres to all metallic materials and subsequently causes wear. Furthermore, pMDI must not come into contact with the skin under any circumstances, let alone be inhaled. Accordingly, the safety precautions during processing are also more complex. Therefore, not every company can process pMDI. The use of pMDI is therefore disadvantageous.

The object of the present invention is to provide a wood fiber board which requires less of the natural resource wood and yet has satisfactory product properties, some of which even comply with relevant standards, and which can be manufactured in conventional production facilities.

This problem is solved with a wood fiber board having the features of claim 1.

Preferred embodiments of the invention are the subject of the subclaims.

The invention essentially consists in the fact that the wood fiber board contains not only wood fibers as a solid component but also coffee grounds as a solid component.

Tests (see below) have shown that a coffee grounds content of up to 80 wt.% results in acceptable strength values. The solids content of the board according to the invention can therefore be up to 80 wt.% and, accordingly, 20 wt.% or more of wood fibers.

In particular, in the invention, a proportion of coffee grounds between 20 wt.% and 45 wt.% is preferred because in this case strength values are achieved which correspond to the standards of a pure wood fiber board.

According to the invention, coffee grounds are preferably used, which are a waste product or residue from coffee preparation or coffee production.

The coffee grounds resulting from the production of instant coffee, also known as soluble coffee, are usually incinerated. However, these coffee grounds, hereinafter referred to as "INSTANT" or "INSTA," can also be recycled, as proposed in the application.

The coffee grounds, which are collected during the preparation of coffee using a portafilter, hereinafter abbreviated as "ST", collect after the coffee preparation in the portafilter of the espresso machine or the coffee vending machines and is usually disposed of. However, these coffee grounds can also be recycled, as proposed in the application.

Coffee grounds generated during the production of instant coffee typically have an average particle size of 125 µm to 2000 µm.

Coffee grounds produced during the production of coffee beverages using a portafilter have an average particle size of 125 µm to 2000 µm.

Both coffee grounds variants can be used equally in the invention and have the advantage that they are available worldwide in very large quantities and have essentially equally good product properties for the present invention.

The use of urea-formaldehyde resin as a binder should, of course, be in the smallest possible amounts, whereby according to the invention the amount of urea-formaldehyde resin is at least 8 wt.%, preferably in a range of 10 wt.% to 12 wt.%, based on 100 wt.% of the sum of wood fibers and coffee grounds.

This means that, for example, if the coffee grounds and wood fibers are 80% by weight and 20% by weight, these components together make up 100% of the solids content. If, for example, 10% by weight of urea-formaldehyde resin is added, this means that the 100% by weight of the finished board is composed of 90% by weight of solids (coffee grounds and wood fibers) and 10% by weight of urea-formaldehyde resin.

With such a binder content, a very uniform distribution of the binder and good homogeneity of the glue distribution throughout the board can be achieved, thus resulting in a very uniform strength structure. Since laboratory-scale tests have shown that a urea-formaldehyde resin content of 10 wt.% to 12 wt.% leads to very uniform results, it is realistic to assume that a minimum content of 8 wt.% of urea-formaldehyde resin will also lead to satisfactory results in the industrial-scale production of the board according to the invention.

The density of the wood fiber board according to the invention is in the range from 500 kg/m ³ to 1,000 kg/m ³ , preferably in the range from 550 kg/m ³ to 950 kg/m ³ . Boards with a density in these ranges are boards used in many applications, in which the board according to the invention can also achieve the good technical properties explained in detail below.

• 1 eine beispielhafte Verfahrensskizze,
• 2 ein Diagramm mit der Rohdichte aller hergestellten und untersuchten Faserplatten,
• 3 ein Diagramm mit der Biegefestigkeit aller hergestellten und untersuchten Faserplatten,
• 4 ein Diagramm mit dem Elastizitätsmodul aller hergestellten und untersuchten Faserplatten,
• 5 ein Diagramm mit der Querzugsfestigkeit aller hergestellten und untersuchten Faserplatten,
• 6 ein Diagramm mit der Längen-, Dicken- und Massenzunahme nach 24 h Wasserlagerung aller hergestellten und untersuchten Faserplatten, und
• 7 ein mögliches Verfahrensschema für die Durchführung im Industriemaßstab.

Further features and advantages of the invention will become apparent from the following description of preferred, non-limiting embodiments of the invention with reference to the accompanying drawings. It shows:

• 1 an exemplary procedure sketch,
• 2 a diagram showing the density of all fibreboards produced and tested,
• 3 a diagram showing the flexural strength of all fiberboards produced and tested,
• 4 a diagram showing the elastic modulus of all manufactured and tested fiberboards,
• 5 a diagram showing the transverse tensile strength of all fibreboards produced and tested,
• 6 a diagram showing the increase in length, thickness and mass after 24 hours of water storage of all manufactured and tested fibreboards, and
• 7 a possible process scheme for implementation on an industrial scale.

In the following, the invention is explained in more detail using an exemplary working procedure for producing a wood fiber board according to the invention which does not limit the scope of protection.

Whenever percentages are given below, they are always by weight.

The wood fiber boards developed within the scope of the present invention were produced using different types of coffee grounds.

As already mentioned, coffee grounds are, among other things, waste products or residues that arise during the production of coffee beverages using portafilters. This type of coffee grounds is abbreviated to ST in the following.

Another waste product used in the invention is coffee grounds, which arise from the production of instant coffee powder. This type of coffee grounds is abbreviated to INSTA. The average particle size is typically between 125 µm and 2000 µm.

The proportions of portafilter coffee and instant coffee used for both coffee variants ranged from 20% to 45% in 5% increments, and additionally 55%, 65% and 75% for the portafilter variant.

As is common in the industrial production of fiberboard, a common urea-formaldehyde resin with different binder contents (10% and 12%) was used.

A urea-formaldehyde resin (UF) was deliberately chosen because of its high reactivity and therefore good, rapid bonding. Furthermore, the resin can be applied to the wood fibers in conventional equipment without the need for additional equipment.

The wood fibers used were MDF-quality, as is standard in industry. The fibers were preferably softwood fibers, such as spruce or a blend of spruce and pine.

However, it is also possible to use recycled fibers from wood fiber materials. In the event that recycling results in damage to the fibers, such as a shortening of the fiber length, that is unacceptable for the specific application, the recycled fibers can also be combined with virgin wood fibers to achieve the desired mechanical properties.

The coffee grounds-based wood fiberboards according to the invention were produced with a target density of 550 kg/ ^m³ and 650 kg/ ^m³ and with a coffee grounds content between 20% and 45% (in 5% increments). The binder contents were 10% and 12%, respectively.

In addition, boards with instant coffee grounds contents of 20%, 35% and 45%, a binder content of 10% and a bulk density of 950 kg/m ³ were produced.

In another series of tests, portafilter coffee grounds proportions of 55%, 65% and 75% were used for portafilter coffee plates with 650 kg/m ³ .

Finally, corresponding reference plates without the addition of coffee (each with the designation REFLAB and further information) were prepared for comparison.

After production, the pressed panels were conditioned for at least 7 days under standard conditions of 20 °C and 65% relative humidity. The panels were then cut using a circular saw and tested for their flexural strength, flexural elastic modulus (EN 310), transverse tensile strength (EN 319), and thickness swelling after 24 hours of water immersion (EN 317). The data were then evaluated and interpreted.

The manufacturing steps for implementing the general working procedure are described below, whereby - for illustrative purposes only - reference is made to the process diagram according to 1 is referred to.

In 1 are a wood fiber board 1 with coffee grounds, the wood fibers 2, the coffee grounds 3, measuring devices 4 for measuring the moisture content using the drying method, measuring devices 5 for weighing the glued wood fiber-coffee grounds mixture, storage container 6 for the dried wood fibers, storage container 7 for the dried coffee grounds, storage container 8 for the resin-hardener mixture (binder), a gluing drum 9, a pneumatic glue gun 10, a storage container 11 for the glued wood fiber-coffee grounds mixture, a board cake frame 12, a hydraulic cold press 13, a press plate 14 and a hydraulic hot press 15.

The parameters described in the manufacturing process were independent of the desired density and identical for ultra-light MDF, lightweight MDF and MDF boards with higher densities. The production of the plates differed essentially only in the total plate mass, which was weighed per defined volume.

In a first step, the moisture content of both the wood fibers and the coffee grounds (portafilter coffee grounds and instant coffee grounds) was determined using the kiln-dried method. A few grams of each material was sampled, weighed, and then stored at a kiln-dried temperature of 103 °C until constant weight was reached. Constant weight means that the materials are dried until the weight of each sample remains constant. The moisture content was then determined based on the difference between the moist and kiln-dried sample. All ratios in the board composition were based on the kiln-dried mass or the dry solids content.

Based on the kiln mass, the desired ratios between wood fibers and coffee grounds, as well as the respective resin content, were calculated and then related to the actual, moist mass (determined moisture content). Since material can be "lost" during the gluing process on a laboratory scale, a 10% safety margin (overweight) was applied to all components for the gluing.

The mixing of wood fibers and coffee grounds, as well as their gluing, took place in a gluing drum with a diameter of 100 cm, a depth of 45 cm, and a rotation speed of 80 rpm. The two solids were tipped into the drum unmixed. The gluing process began immediately after the set rotation speed was reached. Mixing and gluing took place in the same step and took between 5 and 10 minutes, depending on the amount of glue, until the gluing container was empty.

2% ammonium sulfate was added to the UF glue as a hardener. The glue was then applied using a pneumatic glue gun, which was inserted centrally into the gluing drum. The feed pressure and flow rate were selected to create a fine adhesive mist in the gluing drum without the formation of large droplets, thus achieving the most homogeneous glue distribution possible on the fibers. The glued fiber/coffee grounds mixture was then removed from the drum, and the final mass (without a safety margin) was weighed.

The weighed, glued fiber/coffee grounds material was spread by hand as evenly as possible into a 250 x 250 mm board cake frame and pre-compacted within the frame using a hydraulic cold press, from a fiber cake height of several centimeters to a fiber cake height of approximately 5 cm. This pre-compaction step in the frame by cold pressing, i.e., applying pressure but without increasing the temperature, is important because if pre-compaction is insufficient during hot pressing, the fiber cake expands within the board plane, preventing the target density from being achieved.

After pre-compaction, the frame was removed, and 9 mm steel spacers were positioned next to the fiber cake on the press plate, followed by hot pressing. Hot pressing was performed at a pressing surface temperature of 200 °C with a press factor of 10 sec/mm (90 seconds press time), with the press being closed to the spacers at a maximum pressure of 3 MPa.

After completion of the pressing process, the panels were placed vertically to allow for uniform cooling and stored for at least 7 days in a standard climate of 20 °C and 65 % relative humidity before further testing.

The following Table 1 lists all manufactured and tested board variants. Table 1: Overview of fiberboards produced on a laboratory scale Coffee grounds content Wood fiber content Coffee grounds type Bulk density Binder content Designation 0% 100% X 550 kg/m ³ 10% REFLAB-550-UF10 20% 80% portafilter 550 kg/m ³ 10% ST20-550-UF10 25% 75% portafilter 550 kg/m ³ 10% ST25-550-UF10 30% 70% portafilter 550 kg/m ³ 10% ST30-550-UF10 35% 65% portafilter 550 kg/m ³ 10% ST35-550-UF10 40% 60% portafilter 550 kg/m ³ 10% ST40-550-UF10 45% 55% portafilter 550 kg/m ³ 10% ST45-550-UF10 0% 100% X 650 kg/m ³ 10% REFLAB-650-UF10 20% 80% portafilter 650 kg/m ³ 10% ST20-650-UF10 25% 75% portafilter 650 kg/m ³ 10% ST25-650-UF10 30% 70% portafilter 650 kg/m ³ 10% ST30-650-UF10 35% 65% portafilter 650 kg/m ³ 10% ST35-650-UF10 40% 60% portafilter 650 kg/m ³ 10% ST40-650-UF10 45% 55% portafilter 650 kg/m ³ 10% ST45-650-UF10 0% 100% X 650 kg/m ³ 10% REFLAB2-650-UF-10 55% 45% portafilter 650 kg/m ³ 10% ST55-650-UF-10 65% 35% portafilter 650 kg/m ³ 10% ST65-650-UF-10 75% 25% portafilter 650 kg/m ³ 10% ST75-650-UF-10 0% 100% X 950 kg/m ³ 10% REFLAB-950-UF-10 20% 80% Instant 950 kg/m ³ 10% INSTA20-950-UF-10 35% 65% Instant 950 kg/m ³ 10% INSTA35-950-UF-10 45% 55% Instant 950 kg/m ³ 10% INSTA45-950-UF-10 0% 100% X 550 kg/m ³ 12% REFLAB-550-UF12 20% 80% portafilter 550 kg/m ³ 12% ST20-550-UF12 25% 75% portafilter 550 kg/m ³ 12% ST25-550-UF12 30% 70% portafilter 550 kg/m ³ 12% ST30-550-UF12 35% 65% portafilter 550 kg/m ³ 12% ST35-550-UF12 40% 60% portafilter 550 kg/m ³ 12% ST40-550-UF12 45% 55% portafilter 550 kg/m ³ 12% ST45-550-UF12 0% 100% X 650 kg/m ³ 12% REFLAB-650-UF12 20% 80% portafilter 650 kg/m ³ 12% ST20-650-UF12 25% 75% portafilter 650 kg/m ³ 12% ST25-650-UF12 30% 70% portafilter 650 kg/m ³ 12% ST30-650-UF12 35% 65% portafilter 650 kg/m ³ 12% ST35-650-UF12 40% 60% portafilter 650 kg/m ³ 12% ST40-650-UF12 45% 55% portafilter 650 kg/m ³ 12% ST45-650-UF12 20% 80% Instant 650 kg/m ³ 12% INSTA20-650-UF12 25% 75% Instant 650 kg/m ³ 12% INSTA25-650-UF12 30% 70% Instant 650 kg/m ³ 12% INSTA30-650-UF12 35% 65% Instant 650 kg/m ³ 12% INSTA35-650-UF12 40% 60% Instant 650 kg/m ³ 12% INSTA40-650-UF12 45% 55% Instant 650 kg/m ³ 12% INSTA45-650-UF12 Total plates produced 126

For the determination of transverse tensile strength and water immersion, 50 x 50 mm specimens were prepared using a circular saw, and for the bending tests, 230 x 50 mm specimens were prepared. The bulk densities of the individual specimens were determined before the tests.

Bulk density

The bulk density was determined after conditioning in standard climate (20 °C and 65 % relative humidity) on three 50 x 50 mm samples per plate.

The diagram in 2 shows the bulk density of all fiberboards examined.

As from 2 As can be seen, all of the desired density ranges were easily achieved. Very slight density fluctuations can be observed in all three density groups, which indicates a homogeneous scattering and distribution of the fibers and particles. Thus, no significant correlation can be identified between density and the proportion of coffee grounds or binder. This means that the density of the board does not change significantly, even if the proportion of coffee grounds or binder is varied. This effect is due, among other things, to the fact that in the first process step, the moisture content of both the wood fibers and the types of coffee grounds (portafilter coffee grounds and instant coffee) is determined using the kiln-dried method. And that, based on the kiln-dried mass, the desired ratios between wood fibers and coffee grounds, as well as the respective glue content, are calculated and then related to the actual moist mass (determined moisture content).

Of course, the homogeneous production of the fiber cake and its pre-compaction also have an influence on the bulk density.

Flexural strength and flexural modulus of elasticity

The flexural strength and flexural modulus of elasticity provide information about the influence of the wood fiber content, as fibers generally have a positive effect on the flexural properties of materials due to their geometry. Three flexural tests were conducted on the panels according to EN 310, and the flexural strength and flexural modulus of elasticity were determined using a crosshead (Zwick and Roell Z20 universal testing machine). A statistical comparison of the mean values (post hoc Scheffé, p = 0.05) was then performed.

For this purpose, the samples were positioned in a 3-point bending test setup, with the support spacing corresponding to 20 times the plate thickness (approx. 180 mm support spacing).

The loading rate was adjusted so that the breaking force was reached within 60 ± 30 sec.

3 shows a diagram with the flexural strength according to EN 310 of all produced fiberboards.

As from 3 As can be seen, the influence of bulk density is evident in the flexural strength, and the coffee grounds content in the panels also becomes evident in the strength values above a certain amount. Unsurprisingly, the panels in the 550 kg/ ^m³ group exhibit lower strength compared to the 650 kg/ ^m³ or 950 kg/ ^m³ groups. No statistically significant differences can be observed between the panels with coffee content and the reference panels without coffee (each with the designation REFLAB and further information).

In the case of the boards with 650 kg/ ^m³ and 10% binder content, differences can be seen between individual variants, but not between the two pure MDF reference fiberboards, which is why a comparison between the portafilter boards with 55% or more portafilter coffee grounds content and those with 45% or less portafilter coffee grounds content is permissible. If one looks at the group with 20% to 45% portafilter coffee grounds content, no difference can be assumed between the individual board types within the group. Only when the values above 55% are taken into account can one assume a certain trend with decreasing flexural strength with increasing coffee grounds content. In this case, the boards only show a noticeable difference from the reference boards from 55% coffee grounds content and above.

It can therefore be stated that the flexural strength at a density of 550 kg/m ³ or 650 kg/m ³ and a binder content of 10 % or 12 % does not change by adding coffee grounds up to 45 %. significantly changed and yielded surprisingly good values. Depending on the intended use and the required flexural strength, a coffee grounds content of up to 80% can certainly be considered, taking into account the object of the invention to reduce the use of wood in the production of wood fiberboards and to enable the effective further use of coffee grounds.

In the instant coffee sheets with a bulk density of 950 kg/ ^m³, the sheets differ noticeably from the reference sheets starting at 20% coffee grounds. However, higher flexural strength values can be achieved here than with the sheets with a lower bulk density, and sheets with a bulk density of 950 kg/ ^m³ are therefore also preferred within the scope of the invention.

It has been shown that the binder content has no significant influence on the flexural strength in the variants investigated (10% and 12%).

In 4 A diagram showing the modulus of elasticity according to EN 310 of all produced fibreboards can be seen.

A similar picture to the flexural strength is shown in 4 in the modulus of elasticity. Here, too, a clear difference can be seen between the two bulk density groups, although differences between the coffee content are only evident in the 650 kg/ ^m³ plates. Here, both coffee variants show a tendency, but not a statistically significant, decrease in the modulus of elasticity with increasing coffee grounds content. Here, too, the 950 kg/ ^m³ plates show almost identical conditions to those for flexural strength. The only notable exception here are the values for instant coffee, which show lower values than the reference laboratory plate at a coffee grounds content of 35% and above.

It can also be stated that the modulus of elasticity does not change significantly with a bulk density of 550 kg/m ³ or 650 kg/m ³ and a binder content of 10% or 12% by adding coffee grounds up to 45% and results in surprisingly good values.

Transverse tensile strength

The transverse tensile strength of board materials provides insight into the homogeneity of the glue distribution within the board and the fiber distribution (scattering) before pressing. Since the test is performed in parallel with the fiber orientation of the board, factors that are inherently positive for the mechanics of a board, such as fiber length, are of lesser importance here.

For the tests, three specimens per panel were tested according to EN 319, followed by a statistical comparison of the mean values (Post Hoc Scheffe, p=0.05). For the test, the 50 x 50 mm specimens were bonded to aluminum transverse tensile yokes using hot-melt adhesive (Henkel Technomelt Supra 325 HT). The offset between the two yokes was 90° to minimize the torque during the tensile test and thus prevent cracking.

5 shows a diagram with the transverse tensile strength according to EN 319 of all produced fiberboards.

5 shows the absolute values of the measured transverse tensile strength, whereby differences between the two density ranges can be seen here too, with the higher density having the highest transverse tensile strength. In general, there is a very high scatter of values for portafilter coffee, although it should be noted that no statistical difference can be detected between the two reference plate variants with 650 kg/m ³ and 10% binder. Even if individual plate variants show statistically significant differences to their plates with a similar coffee content, overall there is no significant difference to the reference plates. As an example, the portafilter plates with 10% binder are mentioned here; the plate with 45% coffee differs from the variant with 35%, but not from the variants with 40%, 30% or 20% coffee content. The situation is similar for the portafilter plates with 12% binder. It is interesting to note that the dispersion of the portafilter plates decreases with increasing coffee grounds content and that the plates with 55%, 65% and 75% portafilter content differ from the values with 40% and 45% coffee content, but not from the plates with 35% and 25%, and therefore not from the entire group.

In the instant coffee plates, a tendency towards a decrease in strength with increasing coffee content can be seen, but due to the scatter, a statistically significant The results show no discernible difference between the plates with a 10% and 12% binder content in the portafilter plates.

Since all plates were manufactured using the same means, the variation in the portafilter plates at a bulk density of 650 kg/ ^m³ can probably be attributed to the portafilter material. Compared to instant coffee grounds, a higher degree of agglomeration was subjectively observed in the portafilter grounds during processing during gluing in the gluing drum. This could have led to partially greater variations in the coffee grounds content in the plates and thus also explain the variation. Even if values for individual variants appear higher here, they are still within the variation range in relation to the reference and, based on the available values, no significant difference can be assumed. The determined values can therefore be interpreted in such a way that at 650 kg/ ^m³ for instant coffee, with higher coffee contents of over 35%, there was a reduction and for (the smaller sample of) portafilter plates there was no noticeable reduction in transverse tensile strength. In general, it should be noted that with varying board mixing ratios, the total volume of coffee grounds and wood fibers to be glued also varies considerably between the individual board types. A board with, for example, 20% coffee grounds will have a significantly higher volume during gluing than a mixture with 45% or more coffee grounds. This means that the gluing drum is much more heavily filled with low coffee grounds than with mixtures with high coffee grounds. This can significantly influence the distribution of the glue among the fibers and coffee grounds, which is why it cannot be ruled out that a better or more homogeneous gluing could be achieved with higher coffee grounds proportions during the gluing process.

Overall, it can be stated that wood fibre boards with a coffee grounds content of up to 80%, especially from 20% to 45%, have surprisingly good values for flexural strength and flexural elasticity modulus, as well as transverse tensile strength, when bonded with a urea-formaldehyde resin, and this in a density range of 550 kg/m ³ to 950 kg/m ³ .

This applies to both instant coffee grounds and portafilter coffee grounds.

Thickness swelling after 24 hours of water storage

For water storage, three samples per plate were placed in a water bath (water temperature approx. 20 °C) and fixed under the water surface using a metal sieve.

The lengths, thicknesses, and mass gains of 50 x 50 mm samples were determined after 24 hours of water immersion. For this purpose, the samples were simply lightly dabbed and measured after the water bath.

6 shows a representation of the increase in length, thickness and mass after 24 hours of water storage according to EN 317

In 6 again shows a difference between the two bulk density ranges. The most obvious difference is in the values for mass increase, with the boards with the lower binder content tending to gain more mass and, with higher coffee content, sometimes significantly higher mass increases can be seen compared to the reference. The 550 kg/m ³ boards also show a significantly higher increase in thickness swelling than the 650 kg/m ³ boards. The boards with instant coffee and a bulk density of 950 kg/m ³ showed the lowest values, with statistically significantly higher increases being seen with increasing coffee grounds content. The boards with 35% and 45% coffee grounds content show statistically significantly higher values for mass increase and with 45% coffee grounds content show statistically significantly higher values for thickness increase than the reference boards without coffee grounds.

For the portafilter plates with a bulk density of 650 kg/ ^m³ and a binder content of 10%, statistically significant differences compared to the reference plates are only evident in the mass increase of the plate variant with 75%. All other variants differ significantly from each other neither in terms of mass increase nor in thickness swelling, although for the plates with coffee grounds content of >45%, a trend with increasing values can be observed with increasing coffee grounds content. Even for the plates with instant coffee and a density of 650 kg/ ^m³, no statistically significant differences between the different coffee grounds content can be observed.

Interestingly, even when stored in water, no difference can be observed between the two binder contents of 10% and 12%.

With regard to the different properties after water storage, it should be added, however, that the fact that some of the tested boards tend to have poorer properties does not in any way indicate that their use is not advisable, because, as with the mechanical strength, whether a particular composition of a wood fibre board according to the invention is suitable or not depends on the respective intended use of the boards.

Evaluation of the measurement results

All findings obtained in the course of the general procedure for implementing the invention relate to a laboratory-produced wood fiber board using coffee grounds. However, due to the good measurement results, upscaling to an industrial scale is realistic, especially if the board is used in dry areas. Table 2: Requirements for general-purpose boards for use in dry areas according to EN 622-5 Type MDF Characteristic Test procedures Unit Nominal thickness ranges [mm] 1.8 to 2.5 >2.5 to 4 >4to6 >6to9 >9to12 >12to19 >19to30 >30to45 >45 Thickness swelling 24 h EN 317 % 45 35 30 17 15 12 10 8 6 Transverse tensile strength EN 319 N/ ^mm2 0.65 0.65 0.65 0.65 0.60 0.55 0.55 0.50 0.50 Flexural strength EN 310 N/ ^mm2 23 23 23 23 22 20 18 17 15 Bending modulus of elasticity EN 310 N/ ^mm2 - - 2700 2700 2500 2200 2100 1900 Type Light MDF Characteristic Test procedures Unit Nominal thickness ranges [mm] >6to9 >9to12 >12to19 >19to30 >30to45 >45 Thickness swelling 24 h EN 317 % 20 16 14 12 11 11 Transverse tensile strength EN 319 N/ ^mm2 0.45 0.45 0.45 0.45 0.40 0.40 Flexural strength EN 310 N/ ^mm2 20 20 18 15 14 14 Bending modulus of elasticity EN 310 N/ ^mm2 1700 1700 1600 1500 1400 1200 Ultralight MDF Characteristic Test procedures Unit Nominal thickness ranges [mm] >9to12 >12to19 >19 to 30 >30to45 >45 Thickness swelling 24 h EN 317 % 18 14 13 12 12 Transverse tensile strength EN 319 N/ ^mm2 0.15 0.15 0.15 0.13 0.13 Flexural strength EN 310 N/ ^mm2 7.7 6.9 6 5, 1 5, 1 Bending modulus of elasticity EN 310 N/ ^mm2 600 560 510 470 470

Table 2 lists the minimum requirements according to EN 622-5 for industrially manufactured MDF boards for the furniture sector. Experience has shown that laboratory-produced fiberboards are 50% to 66% lower in strength than comparable industrial fiberboards, which is why the laboratory-produced reference board with a bulk density of 550 kg/ ^m³ and 650 kg/ ^m³ without coffee content would currently not meet the requirements of EN 622-5. Although the boards with a bulk density of 950 kg/ ^m³ achieve higher flexural strength and flexural elastic moduli than specified in EN 622-5, their transverse tensile strength remains below the minimum requirements.

In general, it can be stated that the production of laboratory fiberboards always results in compromises in board properties compared to industrially manufactured boards. This is due to the gluing, manual spreading, and the time between glue application and hot pressing. However, the low density dispersion indicates a homogeneous distribution and, by laboratory standards, high-quality and well-glued boards. The influence of the density was significantly greater in relation to the glue content. Regarding strength and water storage, a consistently significant difference was observed, essentially only in the density. The mean values and standard deviations of all tested boards are summarized in Table 3. Table 3: Mean values (MV) including standard deviation (STDEV) of all tested board variants Row labels MW density[kg/m ³ ] STICK Density[kg/m ³ ] MW transverse tensile strength [MPa] TIMBER STRENGTH [MPa] MW bending modulus [GPa] STABW bending modulus [GPa] MWBend strength [MPa] Rod bending strength [MPa] MWThickness increase[%] STABWDleken increase[%] RELAB-550-UF10 519.08 58.00 0.03 0.03 0.60 0.31 4.65 2.65 84% 64% ST20-550-UF10 554.28 30.26 0.05 0.02 0.64 0.12 4.79 0.86 33% 5% ST25-550-UF10 547.44 23.14 0.07 0.02 0.60 0.18 4.53 1.50 28% 3% ST30-550-UF10 545.30 40.15 0.08 0.02 0.59 0.14 4.71 1.32 37% 5% ST35-550-UF10 506.46 77.57 0.18 0.20 0.83 0.28 4.68 3.62 62% 55% ST40-550-UF10 570.93 58.79 0.13 0.09 0.87 0.28 6.16 3.58 37% 13% ST45-550-UF10 556.53 37.08 0.04 0.05 0.51 0.17 5.35 1.24 41% 7% REFLAB-650-UF10 635.98 18.68 0.19 0.08 1.96 0.35 18.52 4.57 26% 4% ST20-650-UF10 632.84 14.41 0.29 0.06 2.21 0.10 20.00 0.76 26% 1% ST25-650-UF10 648.35 42.28 0.08 0.03 1.47 0.19 9.44 2.74 41% 9% ST30-650-UF10 635.29 29.61 0.30 0.07 2.14 0.14 20.50 3.11 27% 4% ST35-650-UF10 642.16 15.23 0.09 0.06 1.67 0.39 11.68 5.84 41% 8% ST40-650-UF10 658.40 11.78 0.27 0.05 1.71 0.19 14.54 1.86 33% 1% ST45-650-UF10 645.15 15.63 0.31 0.06 1.55 0.18 13.89 2.34 29% 2% REFLAB2-650-UF-10 645.06 24.81 0.15 0.07 2.62 0.11 19.88 6.69 17% 8% ST55-650-UF-10 669.87 28.94 0.14 0.05 1.11 0.16 8.31 1.20 36% 9% ST65-650-UF-10 678.07 27.52 0.13 0.06 0.78 0.27 5.67 2.23 39% 14% ST75-650-UF-10 648.93 35.83 0.09 0.02 0.51 0.16 4.01 1.27 35% 6% REFLAB-950-UF-10 922.22 23.59 0.32 0.09 4.38 0.31 41.54 3.40 12% 3% INSTA20-950-UF-10 909.39 16.39 0.34 0.10 3.83 0.24 33.27 1.44 13% 1% INSTA35-950-UF-10 928.58 33.87 0.36 0.14 3.65 0.19 30.59 3.08 14% 5% INSTA45-950-UF-10 924.69 18.79 0.27 0.08 3.14 0.18 24.76 2.34 22% 2% RELAB-550-UF12 589.00 58.62 0.03 0.02 0.75 0.12 5.71 1.00 40% 4% ST20-550-UF12 558.47 31.17 0.07 0.03 0.92 0.21 5.92 1.62 25% 5% ST25-550-UF12 537.29 49.25 0.03 0.02 0.36 0.17 3.21 1.01 36% 5% ST30-550-UF12 546.18 33.72 0.07 0.03 0.66 0.15 4.68 1.12 30% 2% ST35-550-UF12 575.68 17,17 0.10 0.04 0.74 0.17 5.89 1.21 29% 3% ST40-550-UF12 541.30 30.25 0.06 0.02 0.37 0.17 3.32 0.94 39% 5% ST45-550-UF12 577.72 37.94 0.10 0.02 0.47 0.09 3.83 0.95 32% 3% REFLAB-650-UF12 659.65 24.52 0.27 0.11 2.24 0.31 20.25 4.32 22% 7% ST20-650-UF12 625.54 40.73 0.14 0.07 1.86 0.42 12.94 4.57 32% 6% ST25-650-UF12 660.57 22.12 0.13 0.03 1.91 0.23 13.73 2.09 34% 2% ST30-650-UF12 635.17 24.20 0.28 0.08 2.05 0.13 20.16 1.15 28% 3% ST35-650-UF12 663.87 16.84 0.13 0.03 1.80 0.20 14.20 2.22 29% 2% ST40-650-UF12 655.71 58.06 0.07 0.02 1.33 0.31 7.99 0.97 37% 4% ST45-650-UF12 637.69 24.94 0.32 0.10 1.67 0.14 15.63 1.80 25% 3% INSTA20-650-UF12 632.09 19.02 0.23 0.08 1.86 0.25 14.95 2.71 24% 6% INSTA25-650-UF12 635.56 24.34 0.20 0.04 1.88 0.23 15.78 2.42 24% 3% INSTA30-650-UF12 616.85 25.90 0.19 0.06 1.88 0.22 16.75 2.33 23% 2% INSTA35-650-UF12 635.36 28.01 0.19 0.05 1.56 0.21 13.07 2.49 23% 2% INSTA40-650-UF12 634.21 24.25 0.15 0.05 1.48 0.11 11.96 0.46 24% 3% INSTA45-650-UF12 637.27 19.09 0.24 0.03 1.41 0.19 11.96 2.18 21% 2%

Based on the results of the tests carried out, it can be stated that although not all plates met the minimum requirements of EN 622-5, at least in most cases for the portafilter variant with a bulk density of 650 kg/m ³ and a binder content of 10% up to a coffee grounds content of 45%, no statistically significant differences following a trend compared to the reference plates produced in the laboratory without coffee components could be detected.

Assuming that plates with coffee grounds can be produced in industrial production with higher mechanical properties and exhibit similar relationships as in the present patent application, a more pronounced decrease in mechanical properties or a greater increase in mass and thickness after 24 hours of water storage would only be expected with an addition of >45% coffee grounds. Comparing the two coffee grounds variants, the somewhat lower variance of the instant coffee plates is noticeable.

Summary findings:

• - Partikelgröße Kaffeesatz: Kleinere Partikel werden besser zwischen den Fasern eingebettet, als dies bei größeren Partikeln der Fall ist.
• - Faserlänge: Längere Holzfasern sind flexibler als kürzere Holzfasern. Dies ist dann zu berücksichtigen, wenn kürzere Holzfasern, wie etwa solche, die durch Recycling von Abfallprodukten aus der Forstwirtschaft oder der Baustoff- oder Möbelindustrie gewonnen wurden, zum Einsatz kommen.
• - Darrmethode: Die Ausgangsprodukte Holzfasern und Kaffeesatz werden bis zur Gewichtskonstanz getrocknet. Dadurch entsteht ein rieselfähiges Schüttgut, das einfach gelagert und weiterverarbeitet werden kann. Weiters lassen sich die Anteile an Holzfasern und Kaffeesatz sowie der Harzanteil exakt für das weitere Verfahren berechnen.
• - Harzauftrag: Ein homogener Harzauftrag wird dann erzielt, wenn das Harz kontinuierlich auf die vorzugsweise gleichmäßig bewegten Ausgangsprodukte aufgetragen wird. Dadurch ist es auch möglich, den Harzanteil bis auf 8 % zu reduzieren. Bei einer industriellen Herstellung der erfindungsgemäßen Platte kann der Harzauftrag in einem Blowline-Verfahren erfolgen.
• - Vorverdichtung: Die homogene Verteilung von Kaffeesatz und Holzfasern wird nach dem Harzauftrag wesentlich beeinflusst, wenn eine Art Plattenrohling hergestellt wird, der durch Kaltpressen vorverdichtet wurde.
• - Zieldichte: Die Zieldichte der Platten wird durch ein Pressdiagramm mit den Parametern Druck und Temperatur erreicht.

In summary, it can be said that the properties of the board according to the invention, in particular its MDF quality, are influenced by the following material or process parameters:

• - Particle size of coffee grounds: Smaller particles are better embedded between the fibers than larger particles.
• - Fiber length: Longer wood fibers are more flexible than shorter ones. This must be taken into account when using shorter wood fibers, such as those obtained from recycling waste products from the forestry, building materials, or furniture industries.
• - Drying method: The starting materials, wood fibers and coffee grounds, are dried to constant weight. This creates a free-flowing bulk material that can be easily stored and further processed. Furthermore, the proportions of wood fibers and coffee grounds, as well as the resin content, can be precisely calculated for further processing.
• - Resin application: A homogeneous resin application is achieved when the resin is continuously applied to the starting materials, preferably at a uniform speed. This also makes it possible to to reduce the resin content to 8%. In industrial production of the board according to the invention, the resin can be applied using a blowline process.
• - Pre-compaction: The homogeneous distribution of coffee grounds and wood fibers is significantly influenced after resin application if a type of board blank is produced that has been pre-compacted by cold pressing.
• - Target density: The target density of the panels is achieved using a pressing diagram with the parameters pressure and temperature.

Taking these material and process parameters into account, it is the routine practice of a specialist in the field of wood fiber board production to carry out up-scaling to industrial scale.

Thus, the resource-saving wood fiber board made with coffee grounds according to the invention can be produced sustainably and successfully even on an industrial scale. This means that not only large-scale technical parameters but also requirements for environmental compatibility and climate neutrality are met. Since MDF boards are primarily made from spruce wood, this raw material can be saved, especially since spruce is particularly vulnerable to climate change ("spruce dieback"). Furthermore, it must be considered that the ever-increasing global consumption of coffee makes waste disposal a problem. This is because vast quantities of coffee grounds would have to be burned, for example, which, of course, has a negative impact on the carbon footprint.

The resource-saving wood fiber board according to the invention can be provided in MDF and HDF quality, so that areas of application include the construction and furniture industries (including the provision of coffins) and the automotive industry.

Process for producing the resource-saving wood fiber board according to the invention on an industrial scale:

The following will be based on 7 A possible process for producing the resource-saving wood fiber board according to the invention on an industrial scale is described by way of example.

First, wood fibers are produced from wood chips. The starting material for the wood chips is, for example, round wood 16 from the sawmill industry. The choice of wood species in terms of availability and quality can vary regionally. The most commonly used wood species are spruce, pine, and beech. The round wood 16 is first mechanically debarked. For this purpose, the round wood 16 is pressed against rotating blades 17 to remove the bark. The debarked round wood 18 is then chopped into a standard size using saws 19. In the next step, the debarked and chopped round wood 20 is chopped by a disc chipper 21 into wood chips 22. These chips have a length of approximately 25-30 mm, a width of approximately 20-25 mm, and a thickness of approximately 4-6 mm. The oversized pieces generated in this step are then screened out for further shredding.

To remove soil and sand from the wood chips, they are washed in a device 23. During this step, the wood chips are also softened to wash out the resins they contain or to thaw frozen water residues.

The softened wood chips are conveyed via a dewatering screw 24 to the pre-steam tank 25 and heated to approximately 100°C by supplying steam for 3-6 minutes. The wood chips then pass via a conveyor belt into the cooker 26, where they are heated to approximately 170°C with saturated steam.

The heated wood chips are then mixed with the coffee grounds, and the mixture 31 is fed by means of a screw conveyor 27 to a thermomechanical pulping refiner, a defibrator 28 consisting of a stationary disc 30 and an axially adjustable, rotating disc 29 (both with a diameter of approximately 600 mm), at a rotation speed of approximately 1500 rpm. Centrifugal force pushes the wood chips and coffee grounds outward from the center of the discs, gradually breaking them down into fiber bundles and individual fibers (fiber length between 1.0 mm and 5.0 mm, fiber diameter between 10 µm and 500 µm), with the coffee grounds adhering to the fibers. The resulting wood fiber coffee grounds mixture 31' is transported further via an air flow line 32 with a diameter of approximately 120 mm and fed to a blow line 33 There, the wood fiber-coffee grounds mixture 31' is accelerated by steam expansion, enabling uniform gluing due to the resulting turbulence. For this purpose, a solution of urea-formaldehyde resin (UF glue) 35 is introduced into the blow line 33 via water-cooled gluing nozzles 34 with an average droplet size of 25-80 µm, a droplet velocity of approximately 10-35 m/s, a volume flow density of approximately 0.1-0.4 cm ³ /cm ² /s, and a throughput of approximately 3 t/h.

The glued wood fiber coffee grounds mixture 36 is then fed to a flash tube dryer 37. The flash tube dryer 37 consists of a pipe that dries the wet material to the desired residual moisture content within a few seconds. Drying occurs indirectly via a steam heat exchanger.

Following the gluing process, a forming strand 38 approximately 10–15 m long is formed. The glued coffee grounds fiber cake 39 is evenly spread onto this. This is followed by continuous pre-pressing 40 of the coffee grounds fiber cake 39 and subsequent trimming, followed by cutting 42 to the production size of approximately 750 x 260 cm. The main pressing takes place in a multi-story press 41 with a pressing pressure of approximately 7 MPa, a pressing temperature of approximately 170°C, and a pressing time of approximately 6 minutes. After the pressing process, board 1 has a material thickness of approximately 19 mm and is cut to the target dimensions of 366 x 244 cm at press 43. The boards are then stored for 7 days in a standard climate. Both the pressing time and the pressing pressure influence the density of the wood fiber board with coffee grounds according to the invention and the associated intended use and area of application.

Table 4 shows the 7 Table 4: Overview of industrially produced wood fiber boards with coffee grounds Coffee grounds content Wood fiber content Coffee grounds type Bulk density Plate thickness Binder content Designation 45% 55% portafilter 1105 kg/m ³ 8.02mm 14% UF Fiber - GC8920 45_5PORTAFILTERS 45% 55% portafilter 1089 kg/m ³ 8.10mm 14% UF Fiber - GC8920_45_6 PORTAFILTER 45% 55% portafilter 1156 kg/m ³ 7.62mm 12% UF Fiber - GC8920_45_7 portafilter 45% 55% portafilter 1063 kg/m ³ 8.09mm 10% UF Fiber - GC8920_45_8 PORTAFILTER 45% 55% Instant 983 kg/m ³ 7.89mm 12% UF Fiber - GC8920_45_9 INSTANT 45% 55% Instant 787 kg/m ³ 18.87mm 12% UF Fiber - GC19720_45_6 INSTANT Total plates produced 6

Definition:

• Fiber = pinewood fibers
• GC = Ground Coffee
• 8920 = 8 mm, 920 kg/m3
• 19720 = 19 mm, 720 kg/m3
• 45 = coffee grounds content in %
• 1 to 6 = Consecutive numbering of the plates
• PORTAFILTER = coffee grounds from portafilter coffee machines
• INSTANT = coffee grounds from instant coffee production
• UF = urea-formaldehyde resin

The coffee grounds fiberboards listed in Table 4 were measured according to the standards applicable to medium-density fiberboards (MDF). The requirements for these MDF boards are summarized in Table 5. Table 5: Requirements for general-purpose boards for use in dry areas according to EN 622-5. Type MDF Characteristic Test procedures Unit Nominal thickness ranges [mm] 1.8 to 2.5 >2.5 to 4 >4to6 >6to9 >9to12 >12to19 >19to30 >30to45 >45 Thickness swelling 24 h EN 317 % 45 35 30 17 15 12 10 8 6 Transverse tensile strength EN 319 N/ ^mm2 0.65 0.65 0.65 0.65 0.60 0.55 0.55 0.50 0.50 Flexural strength EN 310 N/ ^mm2 23 23 23 23 22 20 18 17 15 Bending modulus of elasticity EN 310 N/ ^mm2 - - 2700 2700 2500 2200 2100 1900 Type Light MDF Characteristic Test procedures Unit Nominal thickness ranges [mm] >6to9 >9to12 >12to19 >19to30 >30to45 >45 Thickness swelling 24 h EN 317 % 20 16 14 12 11 11 Transverse tensile strength EN 319 N/ ^mm2 0.45 0.45 0.45 0.45 0.40 0.40 Flexural strength EN 310 N/ ^mm2 20 20 18 15 14 14 Bending modulus of elasticity EN 310 N/ ^mm2 1700 1700 1600 1500 1400 1200

Table 5 shows that the properties of the plates are divided into nominal thickness ranges.

In order to enable a comparison between the boards according to the invention and the standardized MDF boards, the properties of the boards according to the invention with a nominal thickness between 6 and 9 mm are listed in Table 6a. Table 6a: Measurement results of industrially produced wood fibre boards with coffee grounds with a nominal thickness between 6 mm and 9 mm parameter Requirements according to EN 622-5 Fiber-GC8920_45_ 5PORTAFILTERS Fiber-GC8920_45_ 6PORTAFILTERS Fiber-GC8920_45_ 7PORTAFILTERS Fiber-GC8920_45_ 8 portafilter Fiber-GC8920_45 9INSTANT Type of wood fibers pines pines pines pines pines Binder content 14% UF 14% UF 12% UF 10% UF 12% UF Pressing time 4 min 45 s 4 min 40 s 5 min 30 s 5 min 50 s 5 min 15 s Pressing temperature 165°C 165°C 165°C 165°C 165°C Moisture content before pressing 7.15% 7.80% 6.45% 5.27% 6.30% Elastic modulus (N/mm ² ) >2700N/ ^mm2 3191 3003 2599 2477 2980 Bending strength (N/mm ² ) >23N/ ^mm2 39 36 38 22 31 Thickness (mm) ±0.2mm 8.02 8.10 7, 62 8.09 7.89 Density (kg/m ³ ) >830kg/ ^m3 1105 1089 1156 1063 983 Transverse tensile strength (N/mm ² ) >0.65N/ ^mm2 1.22 1.71 0.97 0.56 0.83 Thickness swelling (%) <17% 15.68 11.05 9.35 8, 34 10, 92 Moisture content (%) 4 - 11% 5, 98 5, 61 5.74 5.21 6.76

To allow further comparison between the boards according to the invention and standardized MDF boards, the properties of a board according to the invention with a nominal thickness between 12 mm and 19 mm are listed in Table 6b. Table 6b: Measurement results of an industrially produced wood fiber board with coffee grounds with a nominal thickness between 12 mm and 19 mm Requirements according to EN 622-5 Fiber-GC19720_45_6 INSTANT Type of wood fibers pinewood Binder content 12% UF Pressing time 5 min 45 s Pressing temperature 165°C Moisture content before pressing 6.97% Elastic modulus (N/mm ² ) >2200N/ ^mm2 2387 Bending strength (N/mm ² ) >20N/ ^mm2 26 Thickness (mm) ±0.2mm 18.87 Density (kg/m ³ ) >760kg/ ^m3 787 Transverse tensile strength (N/mm ² ) >0.55N/ ^mm2 0.52 Thickness swelling (%) <12% 8, 12 Moisture content (%) 4 - 11% 6.95

The measurement results presented in Tables 6a and 6b show that even industrially produced wood fiberboards made with coffee grounds meet the requirements of the applicable standard EN 622-5. This is surprising because wood fibers and coffee grounds are different materials and – see Table 4 – are present in almost equal proportions, namely 45% coffee grounds and 55% wood fibers. The measurement results thus demonstrate that the production of wood fiberboards with coffee grounds is not only technically feasible, but also suitable for the full use and application range of conventional wood fiberboards.

QUOTES CONTAINED IN THE DESCRIPTION

This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO-A2-2018/078391 [0004]

Cited non-patent literature

• The Use of Crop Residues for Boardmaking", Environmental Conservation, Vol. 3, No.1, Spring 1976, pages 59-62 [0003]

Claims (23)

Wood fibreboard with a solid content of wood fibres which are bonded with a urea-formaldehyde resin, characterized in that the wood fibreboard contains coffee grounds and that the solid content of coffee grounds is at most 80% by weight. Wood fiberboard according to Claim 1 , characterized in that the solid content of coffee grounds is between 20 wt.% and 45 wt.%. Wood fiberboard according to Claim 1 or 2 , characterized in that the coffee grounds are a waste product that arises during the production of coffee beverages using a portafilter. Wood fiberboard according to Claim 3 , characterized in that the coffee grounds have an average particle size between 125 µm and 2000 µm. Wood fiberboard according to Claim 1 or 2 , characterized in that the coffee grounds are a waste product that arises during the production of instant coffee. Wood fiberboard according to Claim 5 , characterized in that the average particle size is between 125 µm and 2000 µm. Wood fibreboard according to one of the Claims 1 until 6 , characterized in that the wood fibers are softwood fibers and/or wood fibers obtained by recycling. Wood fibreboard according to one of the Claims 1 until 7 , characterized in that the amount of urea-formaldehyde resin is at least 8 wt.%, preferably in a range of 10 wt.% to 12 wt.%, based on 100 wt.% of the sum of wood fibers and coffee grounds. Wood fibreboard according to one of the Claims 1 until 8 , characterized in that their density is in the range from 500 kg/m ³ to 1,000 kg/m ³ , preferably up to 950 kg/m ³ . Wood fiberboard according to Claim 3 , characterized in that it has a solids content of 20 wt.% to 45 wt.% of portafilter coffee grounds and a content of 10 wt.% to 12 wt.%, based on 100 wt.% of the sum of wood fibers and coffee grounds, of urea-formaldehyde resin, and in that the raw density of the wood fiber board has a value of 500 kg/m ³ to 600 kg/m ³ , in particular of 550 kg/m ³ . Wood fiberboard according to Claim 5 , characterized in that it has a solids content of 20 wt.% to 45 wt.% of instant coffee grounds and a content of 10 wt.% to 12 wt.%, based on 100 wt.% of the sum of wood fibers and coffee grounds, of urea-formaldehyde resin, and the raw density of the wood fiber board has a value of 500 kg/m ³ to 600 kg/m ³ , in particular of 550 kg/m ³ . Wood fiberboard according to Claim 3 , characterized in that it has a solids content of 20 wt.% to 45 wt.% of portafilter coffee grounds and a content of 10 wt.% to 12 wt.%, based on 100 wt.% of the sum of wood fibers and coffee grounds, of urea-formaldehyde resin, and in that the raw density of the wood fiber board has a value of 600 kg/m ³ to 700 kg/m ³ , in particular of 650 kg/m ³ . Wood fiberboard according to Claim 5 , characterized in that it has a solids content of 20 wt.% to 45 wt.% of instant coffee grounds and a content of 10 wt.% to 12 wt.%, based on 100 wt.% of the sum of wood fibers and coffee grounds, of urea-formaldehyde resin, and in that the raw density of the wood fiber board has a value of 600 kg/m ³ to 700 kg/m ³ , in particular of 650 kg/m ³ . Wood fiberboard according to Claim 3 , characterized in that it has a solids content of 20 wt.% to 45 wt.% of portafilter coffee grounds and a content of 10 wt.% to 12 wt.%, based on 100 wt.% of the sum of wood fibers and coffee grounds, of urea-formaldehyde resin, and in that the raw density of the wood fiber board has a value of 900 kg/m ³ to 1,000 kg/m ³ , in particular of 950 kg/m ³ . Wood fiberboard according to Claim 5 , characterized in that it has a solids content of 20 wt.% to 45 wt.% of instant coffee grounds and a content of 10 wt.% to 12 wt.%, based on 100 wt.% of the sum of wood fibers and coffee grounds, of urea-formaldehyde resin, and the raw density of the wood fiber board has a value of 900 kg/m ³ to 1,000 kg/m ³ , in particular of 950 kg/m ³ . Wood fibreboard according to one of the Claims 1 until 15 , manufactured by a process comprising the following steps: a) drying the starting products from wood fibers and coffee grounds to constant weight, b) calculating the desired ratios between wood fibers and coffee grounds and the proportion of urea-formaldehyde resin, c) continuously applying the urea-formaldehyde resin to the dried wood fiber-coffee grounds mixture d) homogeneous scattering to produce a board blank e) pre-compaction of the board blank by cold pressing and f) producing the wood fiber board with coffee grounds by pressing at increased pressure and elevated temperature. Wood fiberboard according to Claim 16 , characterized in that the drying of the starting products from wood fibers and coffee grounds was carried out by means of the kiln method. Wood fiberboard according to Claim 16 or 17 , characterized in that the urea-formaldehyde resin was continuously applied as a fine mist to the dried wood fiber-coffee grounds mixture. Wood fibreboard according to one of the Claims 1 until 15 , produced by a process comprising the following steps: a) calculating the desired ratios between wood fibers and coffee grounds and the proportion of urea-formaldehyde resin, b) producing wood chips from wood, c) thermomechanically breaking down the wood chips to produce wood fibers and mixing them with the coffee grounds in a defibrator, d) continuously gluing the wood fiber-coffee grounds mixture with a solution of urea-formaldehyde resin in a moving air stream (blow line), e) homogeneously scattering the glued wood fiber-coffee grounds mixture to produce a wood fiber-coffee grounds cake, f) producing a board blank by pre-pressing and g) producing the wood fiber board with coffee grounds by pressing at increased pressure and elevated temperature. Wood fiberboard according to Claim 19 for the construction and furniture industry. Wood fiberboard according to Claim 20 , characterized in that it has a thickness of 1.8 mm to 65 mm. Wood fiberboard according to Claim 20 , characterized in that it has a density of 500 kg/m ³ to 2000 kg/m ³ . Wood fiberboard according to Claim 20 , characterized in that it has a density of 110 to 270 kg/m ³ and is used for insulation purposes.