INSULATION MATERIAL AND ITS PRODUCTION

Description

[0001] The invention relates to an insulating material, in particular for sound and / or thermal insulation, and a manufacturing method for such an insulating material.

[0002] Insulating materials made from natural materials, such as straw, flax, hemp or seaweed, are increasingly being used for sound and / or thermal insulation due to their good ecological balance.

[0003] Leather is a natural material and is used in the automotive industry, for example, as car seat upholstery. However, in industrial leather production and processing, leather pieces are often not fully utilized, resulting in leather scraps. Particularly when folding or punching a piece of leather, leather scraps arise in the form of folding shavings, punching grids, or punching scraps, which are not further processed due to, for example, a visual defect. Although these leather scraps have the same excellent natural properties, they are often no longer used in conventional production and are disposed of as waste in landfills. The recycling and disposal methods are uncertain and associated with costs.

[0004] DE 103 20 061 A1 describes the production of a non-sticky, rot-resistant material using leather waste. For this purpose, the leather waste is ground and mixed with a collagen-containing agent and / or a rot-inhibiting agent. This mixture is formed into a thermoplastically deformable mass under pressure and at elevated temperature. This mass can be further processed into a semi-finished product or formed into a three-dimensional part by pressing it into a suitable mold. An insulating material according to the preamble of claim 1 is already known from EP2853648 B1.

[0005] A method for producing an insulating material comprising a plurality of leather fibers is already known from EP0089029 A2.

[0006] Leather waste completely embedded in the collagen-containing agent and / or anti-rotting agent.

[0007] The object of the present invention is to further utilize the leather residues arising during leather production and processing and to avoid costs for their disposal.

[0008] The invention solves this problem by the combinations of features specified in the independent patent claims. Advantageous embodiments and further developments of the invention are set forth in the dependent claims.

[0009] An insulating material according to the invention, in particular for sound and / or thermal insulation, comprises a plurality of leather fibers, preferably made of finished leather. Each leather fiber has a connecting region and a free region. The insulating material further comprises a binding agent with which only the connecting regions of the leather fibers are bonded together.

[0010] The leather fibers required for the insulation material can be obtained from leather scraps by shredding, for example, grinding and / or cutting, if the leather scraps are not already present as leather fibers. In the case of shavings, further processing is often unnecessary, as the shavings are already present as fibers. This insulation material thus allows leather scraps to be further utilized in the form of leather fibers, avoiding the costs of disposing of the leather scraps.

[0011] Due to the use of leather fibers, the insulation material advantageously exhibits the low flammability and excellent thermal insulation properties of leather, making it particularly suitable for thermal insulation. In particular, the insulation material can have a thermal conductivity between 0.01 W / m2<K and 0.1 W / m2<K, preferably between 0.01 W / m2<K and 0.06 W / m2<K. In addition, the leather fibers make the insulation material breathable, moisture-regulating, and particularly durable, which makes it suitable for use in harsh environments.

[0012] By connecting the leather fibers only at the connecting areas, the free areas of the leather fibers can advantageously move relative to each other. This achieves good sound absorption, making the insulating material suitable for sound insulation, especially impact sound. In particular, the insulating material can have a sound absorption coefficient of between 0.5 and 0.95 for sound in the frequency range from 100 Hz to 2000 Hz, preferably from 500 Hz to 1000 Hz. The relatively movable free areas can also advantageously compensate for uneven surfaces or the presence of sharp objects, resulting in a flat surface.

[0013] Due to these advantages, the insulation material is particularly suitable for use in residential or office spaces, as well as for exterior insulation, for example, facades. Further applications can be found in the automotive, marine, and aerospace industries.

[0014] The insulation material can have a thickness of at least 1 mm. In particular, the insulation material can have a thickness of up to 2 mm, 3 cm, 5 cm, 10 cm, 15 cm, or 20 cm. These thicknesses advantageously achieve a particularly good insulation effect.

[0015] The leather fibers can be made of finished leather. Finished leather refers to tanned and finished leather. The leather fibers can have a structured or unstructured arrangement. The leather fibers can all have the same shape or different shapes. Preferably, the ratio between the length of a leather fiber and the width of the leather fiber can be at least 10:1, 20:1, or 30:1. The leather fibers can be chrome-tanned, chrome-free, synthetically tanned, naturally / organically tanned, vegetable-tanned, or plant-tanned leather.

[0016] The connection region can be defined by a positive and / or material-locking connection with the binding agent. At least one leather fiber from the plurality of leather fibers can have a plurality of non-contiguous connection regions, in particular two, three, or four connection regions. The plurality of connection regions enables the connection of several leather fibers to the leather fiber having the plurality of connection regions.

[0017] The free space can be defined by the absence of a form-fitting and / or material-fitting connection with the binder. The free space can be larger, equal to, and / or smaller than the bonding area. Preferably, the ratio between the free space and the bonding area can be at least 1:1, 5:1, or 10:1.

[0018] The binding agent, which can also be referred to as a binder, ensures the dimensional stability of the insulating material and can bond the leather fibers together without prior bonding. The binding agent can bond the bonding areas of all leather fibers together or bond at least two bonding areas of at least two different leather fibers together. The binding agent can bond the bonding areas of the leather fibers together using a form-fitting and / or material-fitting connection. Bonding only the bonding areas together can be understood to mean that the binding agent cannot bond any free areas. In particular, the binding agent cannot bond the bonding area to the free area or bond the free areas of at least two different leather fibers to each other.

[0019] The binder can comprise uncrosslinked resins and / or be free of additives. The binder can be biodegradable, ensuring the biodegradability of the insulation material. This advantageously eliminates the need for recycling steps to break down the insulation material into its components. The binder can be non-free-flowing. Advantageously, with a non-free-flowing binder, prior fixation of the binder to the fiber, such as through compounding, is unnecessary.

[0020] In a further development of the invention, the insulating material comprises an air chamber which is arranged within the insulating material and which is delimited by the free space and the binding agent. Advantageously, a density of the insulating material can be adjusted by the size of the air chamber, thus determining the strength of the sound or thermal insulation of the insulating material. Preferably, a ratio between a volume of the leather fibers and the binding agent to a volume of the air chamber can be at most 2:1, 1:1, or 1:2. The air chamber can be closed or partially open. A partially open air chamber can extend to an outer surface of the insulating material. The partially open air chamber advantageously enables better penetration of sound into the insulating material and thus particularly good sound insulation.

[0021] In a further development of the invention, the leather fibers have a cross-linked helical collagen structure. Advantageously, the binding agent can bond cross-linked helical collagen structures particularly well together.

[0022] In a further development of the invention, the insulating material comprises at least one lamination element for reinforcement, sealing, adjusting the optical properties of the insulating material, and / or adjusting water penetration properties into the insulating material. The lamination element can be arranged on a first outer surface or on a second outer surface opposite the first outer surface. The lamination element can be bonded to the binder. The lamination element can be a fabric for reinforcement, additional binder or a film for sealing an outer surface of the insulating material, a vapor barrier for adjusting water penetration properties, or a design surface in the form of a film for adjusting the optical properties. In particular, the design surface can be embossed, punched, rolled, and / or printed.

[0023] According to the invention, the insulating material has a proportion of 40% by weight to 95% by weight, in particular 70% by weight to 80% by weight, of leather fibers.

[0024] In a further development of the invention, the insulating material has a proportion of 5% by weight to 60% by weight, in particular 20% by weight to 30% by weight, of binder.

[0025] According to the invention, the binder is a polycaprolactone or is based on a polycaprolactone variant, and / or the binder is based on a carboxylic acid ester or a fruit acid. The polycaprolactone, polycaprolactone variant, carboxylic acid ester, and / or fruit acid can be based on crude oil or be of natural origin.

[0026] In a further development of the invention, the leather fibers have a fiber length of 100 µm to 10,000 µm. Advantageously, the insulating material is more homogeneous and has a higher density with shorter fiber lengths, and more stable and has a lower density with longer fiber lengths. In particular, the air chamber can be larger with longer fiber lengths and smaller with shorter fiber lengths.

[0027] The method according to the invention for producing a previously described insulating material comprises the steps of: mixing the leather fibers with the binder to form a mixture; heating the mixture such that the binder is melted to a low viscosity; and bonding only the bonding regions of the leather fibers to one another with the low-viscosity melted binder.

[0028] The manufacturing process can be carried out using a double-belt press, static press, rolling press, or calendering machine. The binder can be powdered prior to melting, with a grain size of the powdered binder being between 0 and 1000 µm. Heating can be dependent on a melting point or a glass transition temperature of the binder. In particular, the mixture can be heated to a temperature that is 3 °C, 5 °C, or 10 °C higher than the melting temperature or the glass transition temperature. For example, the binder can be polycaprolactone with a melting point of 58 °C, with heating taking place to a temperature greater than 58 °C, preferably to 61 °C. For example, the binder can be polyethylene naphthalate with a glass transition temperature of 155 °C, with heating taking place to a temperature greater than 155 °C, preferably to 160 °C.The joining can be a creation of a form-fitting and / or material-fitting connection between the joining areas and the binder.

[0029] In a further development of the invention, the method comprises the step of cooling the heated mixture below a glass transition temperature of the binder or below a melting point of the binder.

[0030] In a further development of the invention, the method comprises the step of shaping the mixture with a mold prior to heating. Advantageously, the insulating material can exhibit locally varying density or strength due to the shaping. During shaping, the mixture can be heated simultaneously with the mold. The shaping can be continuous, semi-continuous, or discontinuous.

[0031] In a further development of the invention, the method comprises the step of: wherein the heated mixture is pressed during the bonding process. Advantageously, the pressing process allows a predetermined density of the insulating material to be achieved.

[0032] In a further development of the invention, the method comprises the step of introducing a laminating element. The introduction can occur before, during, or after heating the mixture. In particular, the introduction can occur after cooling the heated mixture with local heating. The introduction can include the step of thermal lamination.

[0033] The invention will be explained in more detail below using an exemplary embodiment shown schematically in the drawing. In the drawings: Fig. 1 a cross-section of an insulating material for sound or thermal insulation; Fig. 2 an enlarged section of the cross-section of Fig. 1 ; Fig. 3a molecular structure of a tanned leather fiber of the insulation material of Fig. 1 ; Fig. 4 a cross-section of an embodiment of an insulating material for sound or thermal insulation; Fig. 5 a cross-section of a further embodiment of an insulating material for sound or thermal insulation; Fig. 6 a cross-section of yet another embodiment of an insulating material for sound or thermal insulation; Fig. 7 a view of a double-belt press for producing the insulating material from Fig. 1 , Fig. 4 , Fig. 5 and / or Fig. 6 .

[0034] Fig. 1 shows a cross-section of an insulating material 10 for sound or heat insulation, with an enlarged section of the cross-section in Fig. 2 is shown.

[0035] The insulating material 10 comprises a plurality of leather fibers 12 with a proportion of 75% by weight of the insulating material 10 and a binder 18 with a proportion of 25% by weight of the insulating material 10. The insulating material 10 has a thickness D of 5 cm, insulates sound in the frequency range from 100 Hz to 2000 Hz with a sound absorption coefficient of over 0.6 and has a thermal conductivity of 0.035 W / m 2 < K.

[0036] The leather fibers 12 consist of finished leather. The finished leather accrues in the form of leather scraps during leather production and processing and was processed into the leather fibers 12 by grinding and cutting. All leather fibers 12 have a length between 0.8 cm and 1 cm, with a length-to-width ratio between 35:1 and 40:1.

[0037] Each leather fiber 12 has at least one connecting region 14 and at least one free region 16. In the connecting region 14, the binder 18 is positively and / or materially bonded to the leather fiber 12. In other words: the connecting region 14 is defined by a positively and / or materially bonded connection between the leather fiber 12 and the binder 18. In the free region 16, the binder 18 is not positively and / or materially bonded to the leather fiber 12. Thus, each leather fiber 12 is only partially bonded to the binder 18, only partially embedded in the binder 18, and / or only partially embedded in the binder 18.

[0038] Fig. 2 shows that the binder 18 comprises a plurality of separate binder droplets, each binder droplet connecting at least one connecting region 14 of one leather fiber 12 to a connecting region 14 of another leather fiber 12. The binder droplet has the shape of a sphere or an ellipsoid.

[0039] The Fig. 2 The leather fiber, additionally designated by the reference numeral 24, comprises three separate connecting regions 20, 21, 22. Each connecting region 20, 21, 22 has a positive and / or material-locking connection with a binder droplet, which in turn is connected to a connecting region 14 of another leather fiber 12.

[0040] The binding agent 18 is biodegradable. As a result of the biodegradation of the binding agent 18, the bonding area 14 is freely accessible, and the leather fibers 12 can also be decomposed and / or biodegraded. The biodegradation yields a material that does not require pretreatment in a further process step and can be directly converted into another product.

[0041] The insulating material 10 has an air chamber 26 arranged within the interior of the insulating material 10. The size of the air chamber 26 determines the density of the insulating material 10 and thus the strength of the sound or thermal insulation of the insulating material 10. The air chamber 26 is bounded by the free areas 16 and the binding agent 18 and extends to an outer surface 11 of the insulating material 10. Sound can penetrate into the interior of the insulating material 10 through the partially open air chamber 26, with the penetrated sound being absorbed by the insulating material 10.

[0042] Furthermore, the size of the air chamber 26 is selected such that the air contained in the air chamber 26 can hardly move, and therefore only a small amount of thermal energy is transported through the insulating material 10. Therefore, the insulating material 10 is particularly well suited for thermal insulation.

[0043] The insulation material 10 is used in particular for roof insulation, for insulating pipes, walls, or casings, in acoustic walls, in optical acoustic walls or pictures, in absorber boxes, or as a laminated covering on tiles, laminate, or floors. Before use, the insulation material 10 can be in roll form and, for example, can be applied to walls like wallpaper.

[0044] Fig. 3 shows a molecular structure of a tanned leather fiber 12, which has a cross-linked helical collagen structure.

[0045] Fig. 4 shows an embodiment of an insulating material 10'. As far as the Fig. 4 apparent characteristics with those of the Fig. 1 bis 3 are functionally equivalent, the same reference numerals are assigned and the previous explanations apply accordingly, so that the following mainly explains the differences. This also applies to the embodiments of the Fig. 5 und 6 .

[0046] The air chamber 26' of the insulation material 10' of the Fig. 4 is closed and delimited by a first laminating element 28 and a second laminating element 29. The first laminating element 28 is arranged on a first outer surface 30 and the second laminating element 29 is arranged on a second outer surface 32 opposite the first outer surface 30. The binding agent 18 connects the two laminating elements 28, 29 to the leather fibers 12. The two laminating elements 28, 29 in the form of a thin printed plastic film serve to adapt the optical properties of the insulating material 10'. In addition, the plastic film acts as a vapor barrier and prevents water from penetrating the insulating material 10'.

[0047] Fig. 5 shows a further embodiment of an insulating material 10". The insulating material 10" of the Fig. 5 has a first lamination element 28' and a second lamination element 29' in the form of a foam. The foam reduces the thermal conductivity of the insulating material 10", thereby improving thermal insulation.

[0048] In the enlarged view of a section of the insulation material 10" in Fig. 5 The connection of the second laminating element 29' to the leather fibers 12 is shown by the binding agent 18. The first laminating element 28' is also connected to the leather fibers 12 by the binding agent 18.

[0049] Fig. 6 shows a further embodiment of an insulating material 10‴. The insulating material 10‴ of Fig. 6 comprises three insulation zones 34, 36, and 38. The insulation zone 36 has a larger air chamber 26" and thus a lower density than the other insulation zones 34, 38. Therefore, the insulation zones 34, 38 are more stable and robust, whereas the insulation zone 36 provides better sound and heat insulation. Such a sandwich structure facilitates the handling and fastening of the insulation material 10" while simultaneously providing high sound and heat insulation.

[0050] The insulating areas 34, 36, 38 can be manufactured individually and separately from one another, with the insulating areas 34, 36, 38 subsequently being bonded together. The bonding can be achieved by means of the binder 18. Alternatively, a locally higher density, and thus the insulating areas 34, 36, 38, can be created during production by locally heating and locally pressing the insulating material 10‴.

[0051] In an embodiment not shown, the insulating material may comprise two or more than two insulating areas.

[0052] Fig. 7 shows a double belt press 50 for producing the previously described insulating material 10 of Fig. 1 For this purpose, the leather fibers are mixed with the binder to form a mixture 40 without binding the binder 18 to the leather fibers 12 and filled into a container 52 of the double belt press 50.

[0053] By means of a spreading element 54 in the form of a spreading roller, the mixture 40 is spread from the container 52 onto a first belt 56 of the double-belt press 50, which is made of steel or fabric-reinforced PTFE. An adjustable rotational speed of the spreading roller 54 determines the amount of the mixture 40 that is spread onto the first belt 56. The rotational speed of the spreading roller 54 is adjusted such that a predetermined spreading density and / or spreading height is achieved.

[0054] The spread mixture 40 is then pre-compacted by a pre-compactor 58 in the form of a roller. Pre-compaction facilitates the introduction of heat into the mixture 40.

[0055] The double-belt press 50 has a second belt 60 made of steel or fabric-reinforced PTFE, which is arranged opposite the first belt 56. The distance between the first and second belts 56, 60 is adjustable. A small distance results in high pressure on the mixture 40, whereas a large distance results in low pressure on the mixture 40.

[0056] The distance between the first and second belts 56, 60 in combination with the rotational speed of the spreading roller 54 determine the insulating effect of the produced insulating material 10. At a low rotational speed of the spreading roller 54 and a large distance between the first and second belts 56, 60, the produced insulating material 10 has a large air chamber 26 and thus a low density and high insulating effect. At a high rotational speed of the spreading roller 54 and a small distance between the first and second belts 56, 60, the produced insulating material 10 has a small air chamber 26 and thus a high density and low insulating effect.

[0057] Furthermore, the double belt press 50 comprises a heating device 62 with several heating elements, which heat the first and second belts 56, 60 and the mixture 40 arranged therebetween. With the heating device 62, the mixture 40 is heated in such a way that the binder 18 is melted to a low viscosity. In the embodiment of the Fig. 7 The binder 18 comprises polycaprolactone with a melting point of 58 °C, which is why the mixture 40 is heated to a temperature of 61 °C. As a result of the heating and the pressure between the two belts 56, 60, only the connecting areas 20 of the leather fibers 12 are bonded together by the low-viscosity melted binder.

[0058] During the bonding process, the heated mixture 40 is additionally pressed with a first press roller 64 and a second press roller 65 of the double-belt press 50. Pressing with the two press rollers 64, 65 accelerates the bonding process. After bonding, the leather fibers 12 are only partially coated with the binding agent 18.

[0059] The heated mixture 40 is then cooled below the melting point of the binder of 58°C to fix the bonded state. Cooling takes place in a cooling zone 66 of the double-belt press 50, which extends from the two press rollers 64, 65 to one end 68 of the double-belt press 50. During cooling, the pressure exerted by the two belts 56, 60 on the mixture 40 to be cooled is kept constant. In an embodiment not shown, the double-belt press can have a cooling device that extracts heat energy from the two belts to accelerate the cooling of the heated mixture.

[0060] The double belt press 50 thus enables continuous production of the insulation material 10. After leaving the double belt press 50, the insulation material 10 can be rolled up onto a roll as a rolled product or cut into individual panels.

[0061] In a subsequent process step, elements can be attached to the outer surface of the insulating material 10 to increase the surface area of ​​the insulating material 10 and thus further improve sound insulation. Additionally or alternatively, the insulating properties of the insulating material 10 can be adjusted in a subsequent process step by applying heat and pressure, thus changing the density and thickness of the insulating material 10.

[0062] In a process step not shown, a lamination element can be introduced. For this purpose, the lamination element is added to the mixture before contact with the second belt. The lamination element can be a nonwoven, a foam, a reinforcing mesh, or a vapor barrier. The lamination element can then be bonded to the binder by the pressure of the two belts and the heat of the heating device.

[0063] In a further, particularly static, process step (not shown), after heating, particularly after bonding, the mixture can be embossed using an embossing tool. The embossing tool can be a heated and structured embossing roller. The embossing tool can be designed separately from the double-belt press. Alternatively, the double-belt press can include the embossing tool. Embossing can create patterns in the insulating material or create a locally increased density.

Claims

1. Insulating material (10), in particular for sound and / or thermal insulation, comprising - a plurality of leather fibers (12), preferably made of finished leather, - wherein each leather fiber (12) has a connecting region (14) and a free region (16), - a binding agent (18), by means of which only the connecting regions (14) of the leather fibers (12) are connected to one another, characterized in that - the insulating material (10) has a proportion of 40 wt.% to 95 wt.% of leather fibers (12), - wherein the binding agent (18) is a polycaprolactone or is based on a variant of a polycaprolactone and / or wherein a base of the binding agent is a carboxylic acid ester or a fruit acid.

2. Insulating material (10) according to claim 1, comprising - an air chamber (26) which is arranged within the insulating material (10) and which is delimited by the free region (16) and the binding agent (18).

3. Insulating material (10) according to claim 1 or 2, - wherein the leather fibers (12) have a cross-linked helical collagen structure.

4. Insulating material (10) according to any of the preceding claims, comprising - a laminating element (28, 29, 28', 29') for reinforcement, sealing, adjusting the visual properties of the insulating material (10) and / or adjusting the property relating to the penetration of water into the insulating material (10).

5. Insulating material (10) according to any of the preceding claims, - wherein the insulating material (10) has a proportion of 5 wt.% to 60 wt.% of binding agent (18).

6. Insulating material (10) according to any of the preceding claims, - wherein the leather fibers (12) have a fiber length of 100 µm to 10,000 µm.

7. Method for producing an insulating material (10) comprising a plurality of leather fibers (12), preferably made of finished leather, wherein each leather fiber (12) has a connecting region (14) and a free region (16), and a binding agent (18), by means of which only the connecting regions (14) of the leather fibers (12) are connected to one another, wherein the insulating material (10) has a proportion of 40 wt.% to 95 wt.% of leather fibers (12), wherein the binding agent (18) is a polycaprolactone or is based on a variant of a polycaprolactone and / or wherein a base of the binding agent is a carboxylic acid ester or a fruit acid, the method comprising the steps of - mixing the leather fibers (12) with the binding agent (18) to form a mixture (40), - heating the mixture (40) such that the binding agent (18) is melted to a low viscosity, - connecting only the connecting regions (14) of the leather fibers (12) to one another by means of the binding agent (18) melted to a low viscosity, wherein a double-belt press (50) is used to produce the insulating material (10), wherein the mixture (40) is spread by means of a spreading element (54) in the form of a spreading roller onto a rotating first belt (56) of the double-belt press (50) and then the spread mixture (40) is pre-compacted by a pre-compactor (58) in the form of a roller, and wherein a second belt (60) of the double-belt press (50) is arranged opposite the first belt (56) and a distance between the first and second belts (56, 60) is adjusted, wherein the belts (56, 60) are made of steel or of a fabric-reinforced PTFE.

8. Method according to claim 7, comprising - an air chamber (26) which is arranged within the insulating material (10) and which is delimited by the free region (16) and the binding agent (18).

9. Method according to claim 7 or 8, - wherein the leather fibers (12) have a cross-linked helical collagen structure.

10. Method according to any of claims 7 to 9, - wherein the insulating material (10) has a proportion of 5 wt.% to 60 wt.% of binding agent (18).

11. Method according to any of claims 7 to 10, - wherein the leather fibers (12) have a fiber length of 100 µm to 10,000 µm.

12. Method according to any of claims 7 to 11, comprising the step of - cooling the heated mixture (40) below a glass transition temperature of the binding agent (18) or below a melting point of the binding agent (18).

13. Method according to any of claims 7 to 12, comprising the step - wherein the heated mixture (40) is pressed during the connection process.

14. Method according to any of claims 7 to 13, comprising the step of - inserting a laminating element (28, 29, 28', 29').