WO2023079330A1 - Method of producing a semifinished product and a workpiece, and semifinished product and workpiece - Google Patents

Abstract

A method of producing a semifinished product (10) having a fibre component and a matrix is disclosed. The method comprises the following steps: - providing a nonwoven made from natural fibres, - producing a binder mixture containing water and a natural binder, - impregnating the nonwoven with binder mixture and drying the nonwoven to obtain the semifinished product (10). Also disclosed are a method of producing a workpiece (12), a semifinished product (10) and a workpiece (12).

Description

Process for the production of a semi-finished product and a workpiece as well as semi-finished product and workpiece

The invention relates to a method for producing a semi-finished product, a method for producing a sound-absorbing workpiece, a semi-finished product and a sound-absorbing workpiece.

Semi-finished products for the production of sound-absorbing workpieces, for example for use in office furniture, usually contain polyester fleece. For this purpose, a fleece made of a mat of PET fibers and PET bico fibers is used, which form the semi-finished product. The semi-finished product can be reactivated in the sense that it is heated to form and produce the final workpiece, which melts the outer layer of PET-Bico fibers and thus creates a bond between the fibers of the PET material. Such workpieces are therefore predominantly made of petrochemical materials and are not suitable for recycling due to the mixing of PET and PET bico fibers. In addition, the raw materials, namely polyester fibers, are usually produced in Asia, which increases the transport distances. It is therefore the object of the invention to provide a method for producing a semi-finished product that can be reactivated and a sound-absorbing workpiece that use renewable materials. Likewise, a semi-finished product that can be reactivated and a sound-absorbing workpiece that are biodegradable are to be provided.

The object is achieved by a method for producing a semi-finished product with a fiber component and a matrix. The procedure includes the following steps:

- Providing a non-woven fabric made of natural fibers,

- Preparation of a binder mixture containing water and a natural binder,

- Impregnation of the non-woven fabric with the binder mixture and

- Drying of the non-woven fabric to obtain the semi-finished product.

By using natural fibers as the fiber component and a binder mixture containing natural binders, petrochemical materials, such as acrylic resin or PET-Bico fibers, are not necessary so that the semi-finished product can be reactivated and ultimately to produce a workpiece. The inventors have recognized that natural binders can be reactivated in the dried state.

The binder mixture can be a solution, a suspension or an emulsion. For example, the binder mixture contains between 8% and 25% by weight of the natural binder and between 75% and 92% by weight of water.

In one embodiment, the natural fibers of the nonwoven are hemp fibers, flax fibers, kenaf fibers, jute fibers or a combination thereof and/or the natural fibers of the nonwoven are laid and mechanically connected. In this way a fully biodegradable non-woven fabric is obtained. In one embodiment, the non-woven fabric is soaked with the binder mixture for impregnation and then pressed, in particular between two pressure rollers, as a result of which uniform impregnation of the non-woven fabric is achieved.

A foulard can be used for this.

In one embodiment, the nonwoven is dried to a material moisture content of 5% to 15%, in particular 8% to 10%, which means that the semi-finished product is easy to handle and store.

In one embodiment, the natural binder contains starch, in particular more than 95% by weight, preferably more than 99% by weight, as a result of which good reactivability is achieved.

To simplify handling, the starch can be a modified starch, in particular a physically modified starch, can be cold-soluble and/or the starch can be obtained from potato starch.

For example, the starch has a pH of between 6 and 7, especially 6.5 and/or a moisture content of between 10% and 20% by weight, especially between 12% and 16% by weight. .

In order to improve the entry of the natural binder into the nonwoven, the binder mixture can contain between 0.2% by weight and 0.8% by weight of surfactants, in particular 0.4% by weight.

The object is also achieved by a method for producing a workpiece. The procedure has the following steps:

- Providing at least one semi-finished product that was produced as described above, - Reactivating the one semi-finished product or several of the semi-finished products by applying moisture and/or heat, in particular by applying steam, and

- Pressing the one semi-finished product or several semi-finished products into the desired shape in order to obtain the workpiece.

The features and advantages discussed for the method of manufacturing the semi-finished product apply equally to the method of manufacturing the workpiece and vice versa.

Due to the reactivation by means of heat and/or moisture, no non-degradable substances are required to reactivate the semi-finished product.

For example, the semi-finished product is provided by being manufactured as described above.

In one embodiment, before pressing, a surface material is applied to the one semi-finished product or one of the several semi-finished products, which is then pressed with the semi-finished product and forms one of the surfaces of the workpiece, as a result of which the surface of the workpiece is finished.

In particular, the surface material is also made of a biodegradable material.

The object is also achieved by a semi-finished product with a fiber component and a matrix, in particular produced using a method described above, the fiber component comprising a nonwoven made of natural fibers and the matrix being a natural binder.

The features and advantages discussed for the method for producing the semi-finished product and/or for the method for producing the workpiece apply equally to the semi-finished product and vice versa.

The semi-finished product can be viewed as a fiber matrix semi-finished product. For good further processing, the semi-finished product can contain between 25% by weight and 40% by weight, in particular between 30% by weight and 35% by weight, of the natural binder and/or between 75% by weight and 60% by weight. %, in particular between 70% by weight and 65% by weight of the fiber component. This information relates to the dried state of the semi-finished product.

For example, the natural fibers are hemp fibers, flax fibers, kenaf fibers, jute fibers or a combination thereof and/or the natural fibers of the non-woven fabric are laid and mechanically connected. In this way a fully biodegradable non-woven fabric is obtained.

In one embodiment, the natural binder contains starch, in particular more than 95% by weight, preferably more than 99% by weight, as a result of which good reactivability is achieved. This information relates in particular to the dried or unmixed state of the natural binder.

To simplify handling, the starch can be a modified starch, in particular a physically modified starch, can be cold-soluble and/or the starch can be obtained from potato starch.

The object is also achieved by a workpiece, wherein the workpiece is produced from at least one semi-finished product, two semi-finished products or more than two semi-finished products, as described above, and/or is produced using a method as described above.

The features and advantages discussed for the method of manufacturing the semi-finished product, the method for manufacturing the workpiece and/or the semi-finished product apply equally to the workpiece and vice versa.

The workpiece is in particular open-pored. For example, the workpiece is a piece of furniture, such as office furniture. For example, the workpiece is a partition.

In one embodiment, the workpiece contains between 25% by weight and 40% by weight, in particular between 32% by weight and 40% by weight, of the natural binder and/or between 75% by weight and 60% by weight , in particular between 60% and 68% by weight of the fiber component, whereby a durable workpiece is obtained.

For example, the workpiece has a weighted sound absorption coefficient according to ISO 11654: 1997-07 of between 0.5 and 0.6, in particular 0.5 and/or the workpiece has a density of 250 kg/m ³ to 350 kg/m ³ , in particular between 270 kg/m ³ and 290 kg/m ³ , which means that particularly good sound absorption is achieved.

Further features and advantages of the invention emerge from the following description and from the accompanying drawings, to which reference is made. In the drawings show:

1: a semi-finished product according to the invention in a perspective view,

Fig. 2: a workpiece according to the invention from the semi-finished product

Figure 1 was made,

Fig. 3: a schematic flowchart of an inventive

Method for producing a workpiece with a method according to the invention for producing a semi-finished product,

4: a diagram of measured values of a sound absorption measurement on a sound-absorbing workpiece according to FIG. 2 and a 100% PET workpiece from the prior art and

5: a second embodiment of a sound-absorbing workpiece according to the invention, which was also produced from a semi-finished product according to FIG. In Figure 1, a semi-finished product 10 is shown schematically. The semi-finished product 10 can be viewed as a fiber-matrix semi-finished product, with a fiber component and a matrix, with no plastic or petrochemical material being used as the matrix.

The fiber component of the semi-finished product 10 contains a nonwoven made of natural fibers, for example hemp fibers, flax fibers, kenaf fibers, jute fibers or a combination thereof.

The natural fibers are laid and, if necessary, mechanically connected to obtain the non-woven fabric.

The matrix of the semi-finished product 10 is a natural binder containing starch. The proportion of starch is, for example, more than 95% by weight, particularly preferably more than 99% by weight. This information relates to the dry or unmixed state of the natural binder.

The starch is a physically modified starch that is cold-soluble and is based, for example, on potato starch.

In the dried state of the semi-finished product, the semi-finished product 10 contains between 25% by weight and 40% by weight, in particular between 30% by weight and 35% by weight, of the natural binder and between 75% by weight and 60% by weight. , especially between 70% and 65% by weight of the fiber component.

The natural binder can be more reactive to bind the fibers of the nonwoven, functionally similar to a thermoplastic matrix.

FIG. 2 shows a sound-absorbing workpiece 12 according to the invention, which was produced from semi-finished product 10, for example.

The exemplary embodiment shown according to FIG. 2 is made from two semi-finished products 10 and is therefore multi-layered. It is also conceivable that the sound-absorbing workpiece 12 is made from only one semi-finished product 10 or more than two of the semi-finished products 10 .

The workpiece 12 contains between 25% and 40% by weight of the natural binder and between 75% and 60% by weight of the

Fiber component, in particular between 32% by weight and 40% by weight of the natural binder and between 60% by weight and 68% by weight of the

fiber component.

FIG. 3 shows a schematic flow chart of a method according to the invention for producing the reactivatable semi-finished product 10 and of a method according to the invention for producing the sound-absorbing workpiece 12 which makes use of the method for producing the reactivatable semi-finished product 10 .

In a first step H1, the nonwoven made of natural fibers for the semi-finished product 10 is provided. For this purpose, the natural fibers are, for example, laid and mechanically connected, whereby the non-woven fabric is produced.

As previously described, the natural fibers are hemp fibers, flax fibers, kenaf fibers or jute fibers. The non-woven fabric can also have fibers from different plants.

In a step H2, which can take place simultaneously, before or after step H1, a binder mixture is prepared. The binder mixture contains water, the natural binder and surfactants. The binder mixture is, for example, a solution, a suspension or an emulsion.

For example, the binder mixture contains 8% by weight of the natural binder, 0.2% to 0.8% by weight, in particular 0.4% by weight, of surfactants and 91.6% by weight of water. The surfactants are biodegradable and in particular can also be a natural product.

As described above, the natural binder contains starch, in particular more than 95% by weight, preferably more than 99% by weight.

The starch can be a physically modified starch that is cold-soluble and was obtained from potato starch.

For example, the starch has a pH of between 6 and 7, especially 6.5 and a moisture content of between 10% and 20%, especially between 12% and 16% by weight. Such a starch is sold, for example, by Emsland-Stärke GmbH under the trade name EMPRE KST.

In step H3, the nonwoven is impregnated with the binder mixture.

For this purpose, the non-woven fabric is impregnated with the binder mixture (step H3.1).

The impregnated nonwoven is then pressed in step H3.2. Two pressure rollers, a so-called foulard, can be used for this purpose, between which the impregnated non-woven fabric is fed.

The impregnated and pressed nonwoven is then dried in step H4. The drying takes place, for example, up to a material moisture content of the nonwoven fabric of 5% to 15%, in particular up to a material moisture content of between 8% and 10%, preferably 9%.

The non-woven fabric dried to the specified material moisture content thus contains the natural binder and is now the semi-finished product 10 that can be reactivated.

Because of the natural binder, the semi-finished product 10 that can be reactivated can be reactivated and further processed like a fiber-matrix semi-finished product. For reactivation, the semi-finished product 10 can be exposed to moisture and heat, e.g. steam, are treated, whereby the binder is reactivated.

In order to produce the sound-absorbing workpiece, one or more of the previously produced reactivatable semi-finished products 10 are now provided in step W1.

This is done in particular by means of the previously described method for producing the reactivatable semi-finished product 10. Step W1 can therefore include steps H1 to H4.

Depending on the sound-absorbing workpiece 12 to be produced, one semi-finished product 10, two semi-finished products 10 or more than two semi-finished products 10 can be provided and processed into a sound-absorbing workpiece 12. Accordingly, the sound-absorbing workpiece 12 then has one layer, two layers or more than two layers of natural fibers.

In step W2, the semi-finished product 10 or the plurality of semi-finished products 10 is reactivated, for example by the application of steam, as a result of which moisture and heat are added to the semi-finished product, in particular to the dried binder. In particular, the water vapor has a temperature of 100.degree.

In step W3, which can already take place beforehand, a surface material can also be applied to the semi-finished product 10 or one of the several semi-finished products 10. This is done, for example, by placing the surface material on the uppermost or lowermost semi-finished product 10.

In step W4, the one or more semi-finished products 10 and a surface material optionally located thereon are pressed together and brought into the desired shape. The sound-absorbing workpiece 12 is obtained by pressing. It is conceivable that the reactivation of the semi-finished product 10 takes place at the same time as the pressing. For example, the moisture of the semi-finished product 10 is used in that the semi-finished product 10 is heated in the press, so that the water contained reactivates the natural binder as water vapor. The semi-finished product 10 can also be moistened before being introduced into the press in order to generate steam in the press.

The sound-absorbing workpiece 12 can be brought into almost any shape during pressing, such as arched and curved workpieces.

The workpiece 12 may be office furniture, such as part of a partition.

This formability is very similar to a standard fiber matrix semi-finished product, which can also be processed into almost any shape.

The sound-absorbing workpiece 12 has open pores and accordingly has high sound absorption.

The density of the workpiece 12 is between 250 kg/m ³ and 350 kg/m ³ , in particular between 270 kg/m ³ and 290 kg/m ³ .

For example, the sound-absorbing workpiece 12 has a weighted sound absorption coefficient according to ISO 11654: 1997-07 between 0.5 and 0.6, in particular 0.55.

FIG. 4 shows two series of measurements of the sound absorption coefficient measured according to DIN EN ISO 354:2004-12.

The measuring points marked with circles originate from a measurement on a sound-absorbing component from the prior art consisting of 100% PET, with a thickness of 12 mm and a density of 200 kg/m3. The measurement points marked with the squares originate from a corresponding measurement on an exemplary sound-absorbing workpiece 12 according to the invention.

The exemplary workpiece 12 contained 65% by weight of hemp fibers, 34.6% by weight of the natural binder, ie the starch, and 0.4% by weight of surfactants. The density of the workpiece with a thickness of 12 mm was 280 kg/m ³ and was made from two semi-finished products 10 .

The starch used for production is sold by Emsland-Stärke GmbH under the trade name EMPRE KST. This starch is a physically modified cold water soluble potato starch having a pH of 6.5 and a moisture content of 14% by weight.

To produce the semi-finished products 10, a binder mixture of 8% by weight of the natural binder, 0.4% by weight of surfactants and 92.3% by weight of water was used. The semi-finished products 10 were dried to a material moisture content of 9%. The reactivation took place with steam at 100°C.

For each material, a wall of the respective material with a width of 950 mm, a height of 1750 mm and a thickness of 12 mm was measured vertically in an echo chamber in accordance with ASTM C 423-17 (Revision 17: 2017-02) and DIN EN ISO 12999-3: 2020-11 placed at 30 mm from the ground. The measurement setup and the dimensions of the wall were identical for the two materials. The measurement was carried out according to DIN EN ISO 354:2003-12.

It can be clearly seen in FIG. 4 that the sound absorption of the sound-absorbing workpiece 12 according to the invention corresponds to that of the known material from the prior art. In particular, it has the same weighted sound absorption coefficient aw of 0.55 (H) according to ISO 11654:1997-07. It is thus possible with the aid of the method according to the invention to produce a sound-absorbing workpiece 12 which, with the exception of the surfactants, is produced entirely from natural products and is free from petrochemical components. On the one hand, it can be made from renewable raw materials and, on the other hand, it is completely biodegradable.

However, it is conceivable that the surfactants are not only biodegradable, but are also produced biologically and/or are a natural product.

FIG. 5 shows a second embodiment of a sound-absorbing workpiece 12 according to the invention, which corresponds to that of the first embodiment. In the following, therefore, only the differences will be discussed.

The sound absorbing work 12 of the second embodiment, unlike that of the first embodiment, has a textured surface formed by pressing. The textured surface has a

Grid of circular bumps. The surface of the sound-absorbing workpiece 12 can thus be refined by pressing, without the need for further materials.

Claims

Expectations 1. A method for producing a semi-finished product (10) with a fiber component and a matrix, the method comprising the following steps: - Providing a non-woven fabric made of natural fibers, - Preparation of a binder mixture containing water and a natural binder, - impregnation of the non-woven fabric with the binder mixture, and - Drying the non-woven fabric to obtain the semi-finished product (10). 2. The method according to claim 1, characterized in that the natural fibers of the non-woven fabric are hemp fibers, flax fibers, kenaf fibers, jute fibers or a combination thereof and/or the natural fibers of the non-woven fabric are placed and mechanically connected. 3. The method according to claim 1 or 2, characterized in that the non-woven fabric is impregnated with the binder mixture for impregnation and then pressed, in particular between two pressure rollers. 4. The method according to any one of the preceding claims, characterized in that the nonwoven is dried to a material moisture content of 5% to 15%, in particular from 8% to 10%. 5. The method according to any one of the preceding claims, characterized in that the natural binder contains starch, in particular more than 95% by weight, preferably more than 99% by weight. 6. The method according to claim 5, characterized in that the starch is a modified starch, in particular a physically modified starch, is cold-soluble and/or the starch was obtained from potato starch. 7. The method as claimed in any of the preceding claims, characterized in that the binder mixture contains between 0.2% by weight and 0.8% by weight of surfactants, in particular 0.4% by weight. 8. A method for producing a workpiece (12), the method comprising the following steps: - Providing at least one semi-finished product (10) produced according to one of the preceding claims, - Reactivating the one semi-finished product (10) or several of the semi-finished products (10) by applying moisture and/or heat, in particular by applying water vapor and - Pressing the one semi-finished product (10) or the several semi-finished products (10) into the desired shape in order to obtain the workpiece (12). 9. The method according to claim 8, characterized in that before pressing a surface material is applied to the one semi-finished product (10) or one of the several semi-finished products (10), which is then pressed with the semi-finished product (10) and one of the surfaces of the workpiece (12) forms. 10. A semi-finished product with a fiber component and a matrix, in particular produced using a method according to any one of claims 1 to 7, characterized in that the fiber component comprises a nonwoven made of natural fibers and the matrix is a natural binder. 11. Semi-finished product according to claim 10, characterized in that the semi-finished product contains between 25% by weight and 40% by weight, in particular between 30% by weight and 35% by weight, of the natural binder and/or between 75% by weight. % and 60% by weight, in particular between 70% by weight and 65% by weight, of the fiber component. 12. Semi-finished product according to claim 10 or 11, characterized in that the natural fibers are hemp fibers, flax fibers, kenaff fibers, jute fibers or a 16 Combinations thereof and/or wherein the natural fibers of the non-woven fabric are laid and mechanically connected. 13. A semi-finished product according to any one of claims 10 to 12, characterized in that the natural binder contains starch, in particular more than 95% by weight, preferably more than 99% by weight. 14. Semi-finished product according to claim 13, characterized in that the starch is a modified starch, in particular a physically modified starch, is cold-soluble and/or the starch was obtained from potato starch. 15. Workpiece, characterized in that the workpiece (12) is produced from at least one semi-finished product (10), two semi-finished products (10) or more than two semi-finished products (10) according to one of claims 10 to 14 and/or with a method according to Claim 8 or 9 is made. 16. Workpiece according to claim 15, characterized in that the workpiece (12) contains between 25% by weight and 40% by weight, in particular between 32% by weight and 40% by weight, of the natural binder, and/or between 75 % by weight and 60% by weight, in particular between 60% by weight and 68% by weight of the fiber component. 17. Workpiece according to claim 15 or 16, characterized in that the workpiece (12) has a weighted sound absorption coefficient according to ISO 11654: 1997-07 between 0.5 and 0.6, in particular 0.5 and/or a density of 250 kg/m ³ to 350 kg/m ³ , in particular between 270 kg/m ³ and 290 kg/m ³ .