WO2009111808A1

WO2009111808A1 - High-temperature resistant two-component insulating mat, method for the production thereof and use thereof

Info

Publication number: WO2009111808A1
Application number: PCT/AT2009/000081
Authority: WO
Inventors: Faisal H. J. Knappe; Josef Wielend
Original assignee: Lenzing Plastics Gmbh
Priority date: 2008-03-11
Filing date: 2009-02-27
Publication date: 2009-09-17
Also published as: AT506406A4; AT506406B1

Abstract

The present invention relates to a high-temperature resistant two-component insulating mat, comprising a non-bonded mat made of a first high-temperature resistant fiber, which is reinforced with a second high-temperature resistant fiber, wherein the two fibers can be differentiated from each other, for example, based on the individual fiber lengths thereof. The invention further relates to a method for the production thereof, and to uses of said material. The insulating material according to the invention additionally has a significantly lower weight than the previously known materials and has further advantages for use.

Description

High-temperature resistant two-component Dämmylies, process for its preparation and its use

The present invention relates to a high-temperature resistant two-component insulating material, a method for its production and uses of this material. The insulation according to the invention also has a much lower weight than the previously known materials and has further advantages in use.

High temperature resistant insulation materials are used in large quantities, for example in the automotive industry. They are used primarily in the engine compartment to shield the high temperatures that occur and loud engine noise, but also to prevent rattling noises.

For such purposes, those skilled in the general first

Foams known. These foams are easy and inexpensive to manufacture. For the applications mentioned, however, they would have to have a considerable thickness of at least several cm at the required insulation performance. This is not acceptable in the context of today generally desired compact design. In addition, the

Foams themselves easily flammable and must be made flame retardant by additives. Many of the known foam materials are also not resistant to solvents, for example to motor vehicle fuels. Another disadvantage of foams is their ability to absorb liquids and moisture, especially if they have an open-pore structure.

Another solution is so-called "heavy mats", which can be made of polyurethane with mineral fillers, for example, which are applied to the body parts to be insulated, but due to their high density they are often only about 3-5 mm thick, but at this thickness a basis weight of up to 12 kg / m ^2. Due to their plastic content, they are only partially resistant to aggressive media and can be used with high temperatures burn or melt, in addition, larger amounts of toxic gases may arise.

To save the weight of such a heavy mat, z. As the WO 04/056639 A1 constructive measures. For example, the

Air conditioning components are to be mounted in the front wall module of a motor vehicle in order to insulate the mass of the vehicle interior with respect to the engine noise. In addition, however, a foam must be used for thermal insulation. Thus, this solution also requires an insulating material with the disadvantages mentioned above and makes additional structural restrictions in the arrangement of individual units necessary.

Another need for protection against high temperatures and prevention of rattling noises is the sheathing of the harnesses and other transport lines in the engine compartment. In addition, these transport lines must be protected against abrasion and cutting in case of accidents.

From WO 99/50943 A1 a protective casing is known, which is designed in the form of a winding tape. Their structure is essentially two-layered. It consists of two textile layers, wherein the winding tape has an inner textile layer of a nonwoven facing the protective object and an outer textile layer of a Kettstuhlknit velor applied to the inner layer. Both textile layers are glued together. The adhesive is applied in partial areas, for example in the form of a heat-activatable nonwoven or film. All textile layers are made of synthetic fibers, such as polyamide or polyester. A needle felt is used as a fleece. The outer textile layer forms a Kettstuhlknit velor, consisting of a knitted lower chain and a knitted in the lower chain upper chain. One speaks of a 2-part Kettstuhlwirkwarenvelours. The upper chain has from the fabric or textile level outwardly projecting, highly roughened, overly trained velor loops. This wrap band should spirally wound on the object to be protected. On the surface facing the object to be protected, an adhesive layer is present.

This wrapping tape is too thick and therefore difficult to handle, especially in narrowing spaces and Verlegeradien. Especially along hard, sharp edges its effectiveness can be absolutely contained by manual misconduct. It offers no permanent protection over the entire lifetime in vehicles, machines or the like.

For example, there is a need for insulating materials in motor vehicles in the interior, in which the passengers are located. Here, on the one hand, it is necessary to reduce external noise, such as wind noise. On the other hand, the acoustics of this room should be influenced so that the normally desired sounds such as conversation and music are perceived as pleasant. Among other things, a good sound absorption capacity is crucial to prevent reflections.

In the prior art, for example from the German utility model DE 77 21 875 foam layers of polyurethane foam with a heavy spar and / or lead dust admixture are known, which are foamed directly into the body inside. Such solutions are already disadvantageous because of their high weight, the elaborate processing and easy flammability.

WO 2004/001718 A1 discloses a sound absorber with a molded part made of thermoplastic material, preferably polyester, and a second part, which preferably consists of a heavy mat. Both parts together surround a cavity provided with spacers. This solution basically also has the disadvantages already mentioned and is also relatively thick. Today foam boards are preferably used to improve the interior acoustics, which are partially laminated with aluminum foil or the like. These are lightweight and easy to manufacture and process in comparison to the previously mentioned solutions. However, the foams used can have a high fogging tendency. Fogging is the evaporation of volatiles from the hard foam, which can lead to odors in the vehicle interior or even damage to health and can be reflected on the inside of the window panes and obstruct the view.

High temperature resistant fibers and nonwovens made therefrom are already known for a very wide variety of applications. Among other things, EP 1791939 A1 discloses filter fleece for air filters in motor vehicles containing oxidized polyacrylonitrile (Panox®) fibers. However, these filter webs mainly consist of combustible synthetic fibers. In the case of high temperatures, the Panox® fibers should ensure that the shape of the fleece is retained, while the other synthetic fibers burn or melt. However, the fleece loses its essential function and it produces harmful gases. The way in which the web is made from the fiber blend is not disclosed. Nonwovens made of 100% high temperature resistant fibers such as Panox® are also known in principle from this document.

Also known from DE 19728523 A1 are nonwovens of inorganic fibers such as glass, basalt, mineral or metal fibers, which are produced by hydroentanglement.

DE 4141659 A1 discloses a method and an apparatus for the continuous production of mineral wool nonwovens.

Also nonwovens made of several high temperature resistant fiber types are known (DE000069519585T2). Such nonwovens are produced by mixing the fibers and then web formation. To solidify the nonwovens are then mechanically needled. DE 102005053915 A1 describes a vehicle interior lining which contains two types of layer structure fibers in a nonwoven. Both types of fibers should preferably consist of polyester and be solidified by means of a hot melt binder. Such a panel is expensive to produce, melts and burns easily. As an alternative, it is described that one of the two types of fibers may be an inorganic fiber. However, this does not change the already mentioned disadvantages.

Both the different solidification technologies and the addition of binders increase the effort in fleece production and can cause problems in the application. Techniques like the mechanical one

Needling or hydroentangling requires additional, precisely manufactured machines. The presence of binders, usually polymers or other organic materials, also requires additional aggregates to apply the binder and to fix, i. H. Heating and / or pressing and is also problematic when exposed to higher temperatures, as these binders then at least partially decompose, melt or even burn.

In view of this state of the art, the object was to develop an insulating material which is both light and thin and relatively inexpensive to manufacture and easy to handle, but on the other hand has high temperature resistance, high mechanical and chemical resistance and very good sound and thermal insulation properties and acoustic properties. In addition, the object was to provide a simple method for producing this insulating material.

This object is achieved by an insulating material comprising an unconsolidated nonwoven fabric from a first high temperature resistant fiber reinforced with a second high temperature resistant fiber, wherein the two high temperature resistant fibers are clearly distinguishable from each other. As high temperature resistant fibers should be understood that have a melting temperature of at least 400 ⁰ C. Surprisingly, it has been found that the different individual fiber lengths of the first and second types of fibers have a significant influence on the insulating properties of the material according to the invention. It is particularly advantageous if the first fiber has a significantly greater single-fiber length than the second fiber. Thus, the first type of fiber should have at least 5 times the length of the second type of fiber, in a preferred embodiment even at least 20 times the length. In particular, a single fiber length of between 20 mm and the length of so-called continuous filaments known to those skilled in the art will be advantageous for the first type of fiber. Preferably, this is also a single fiber length between 20 mm and 100 mm. For the second type of fiber a single fiber length between 0.1 mm and 2.0 mm is advantageous, in a preferred embodiment between 0.6 and 1, 0 mm.

It is not necessary for both types of fibers that each individual fibers have exactly the same length. However, the length distribution of the first type of fiber is dictated primarily by the requirements that the nonwoven manufacturing process used requires and should be as uniform as possible for most of these processes. The length distribution of the second type of fiber depends mainly on the nature of its manufacture and will generally have a broader distribution curve. Such a broader distribution curve is probably even advantageous for the insulating effect and for the mechanical strength of the material according to the invention.

In a likewise preferred form of the insulating material according to the invention, the first and the second fiber differ on account of their chemical composition and / or due to their density. However, the most important selection criterion for both is always the high temperature resistance.

In this case, the first fiber is preferably selected from the group comprising glass fibers, basalt fibers, aramid fibers, carbon fibers, metal fibers, ceramic fibers, mineral fibers and oxidized polyacrylonitrile fibers. Oxidized polyacrylonitrile fibers are also known under the brand name Panox®. The second fiber is also preferably selected from the group consisting of glass fibers, basalt fibers, aramid fibers, carbon fibers, metal fibers, ceramic fibers, mineral fibers and oxidized polyacrylonitrile fibers. Particularly preferred types of fibers in aqueous media have a highly fibrillated surface. These fibrils ensure a mechanical consolidation of the insulating material according to the invention and for a high insulation performance.

In this case, the second fiber, in particular if it is a short fiber, also have a specification that makes them unsuitable for common uses. For example, in some production processes, cutting waste is produced which can be used according to the invention.

In particular, aramid short fibers are very well suited for the material according to the invention. They show swelling in aqueous media and a strongly fibrillated surface. Suitable such aramid short fibers are commercially available, for example, under the name "Twaron PuIp".

Particularly preferred is an insulating material in which the first fiber has both a greater single fiber length than a different chemical composition than the second fiber.

An example of such a preferred embodiment is a

Insulating material from a non-bonded web of approx. 70 mm long Panox® fibers reinforced with aramide fibers of approx. 0.5 to 1.2 mm in length.

Depending on the particular application, the insulating material according to the invention may also comprise several layers of fleece and reinforcing fiber. Thus, for example, for an interior lining of a passenger car, an insulating material of 6 individual layers is well suited. Such a mat has, for example, a thickness of 1, 2 mm and a basis weight of about 600 g / m ² . The individual layers of the insulating material are preferably joined together with a hot-melt adhesive, for example based on polyester, or with an adhesive adhesive, for example based on acrylate.

The invention also provides a process for producing an insulating material, wherein first an unconsolidated nonwoven fabric is provided from a first high-temperature-resistant fiber. The nonwoven fabric can basically be produced by any suitable method. The simple laying of the individual fibers with air ("airlaid") or with a card or carding machine is well suited. "Unconstrained" means, for the purposes of the present invention, above all the absence of binders. A hydrodynamic consolidation by water needling or the like is not required. However, it may be advantageous to press the web before applying the second type of fiber either by means of two press rolls or weakly mechanically needling. However, an intensive needling would result in a too hard material and would not be suitable for the production of a thin insulating material.

This unconsolidated web is sprayed with a dispersion of the second high-temperature resistant fiber in an aqueous medium, the aqueous medium is first removed mechanically, for example by means of press rolls, and the insulating material is then dried.

Depending on the required end product then several of the individual layers are connected together.

By introducing the second type of fiber, the strength of the web is significantly increased. Therefore, the nonwoven fabric of the first type of fiber can initially be used without being consolidated. Aramid short fibers, for example, swell easily when dispersed in water. In the swollen state, they combine very intimately with the individual fibers of the fleece and the mechanical hardening effect occurs during subsequent drying. But since this type of solidification allows a much higher mobility of the individual fibers than, for example, a binder, this is Insulating material according to the invention soft and flexible enough for the applications described.

According to the invention, the insulating material can be used especially for sound insulation, to improve the acoustics, for example in vehicle interiors, and for thermal insulation. If necessary, several

Layers of insulating material connected to each other. Preferably, the insulating materials described here are used in a motor vehicle.

The insulating material according to the invention is suitable both single-layer and multi-layered well for producing a composite material for protecting the harnesses and other transport lines in the engine compartment against high temperatures and to prevent rattling noises. In addition, these transport lines must be protected against abrasion and cutting in case of accidents. To produce such a composite material, the insulating material according to the invention is combined with a layer of woven inorganic fiber and an inorganic shielding layer bonded directly to the woven inorganic layer. Such composite materials are described, for example, in Research Disclosure 520001 of August 2007.

In the following, the production of the insulating material according to the invention and its properties will be described by means of examples. The examples merely serve to illustrate the invention and do not limit the scope of this. However, the invention is not limited to the subject matter of these examples, but includes all other embodiments based on the same inventive concept.

Example:

An initially unconsolidated web of about 70 mm long Panox® fibers is produced with an areal weight of 50 g / m ² by an airlay method ("airlaid"), then passed between two press rolls and placed on a wire belt % by weight dispersion of about 0.5 to 1.2 mm long commercially available aramid

Short cut fiber (Twaron® Pulp 1094) made in water. The dispersion is sprayed evenly onto the Panox® nonwoven using a suitable sprayer placed above the screen belt to give an additional 20 g / m ² (measured as dry fiber). Through the mesh of the screen belt, the excess water flows due to gravity. It is not sucked off. After the insulating material has been heavily dewatered in this way, it is pressed by pressing rollers and then thermally dried to the equilibrium moisture content. This gives an insulating material with a basis weight of 70 g / m ² .

The sound absorption coefficient of different thicknesses of insulation material with normal sound incidence was measured on the insulating material according to the frequency range method (FFT method) according to ISO 10534-2 (tester: TFS sound impedance measuring system, measuring tube SAB 105_30; distance measuring microphone to the sample: 90 mm; distance measuring microphone - reference microphone: 24 mm, sample geometry: round

Blanks 30 mm in diameter; Sample thickness according to product thickness; Measuring frequency range: 320 to 6250 Hz. The reference sample used was a 20 mm steel plate.

FIGS. 1 to 5 show the results of these measurements, whereby it becomes clear that even one layer of the insulating material according to the invention has a better sound absorption than a 20 mm thick steel plate.

The measured curves show:

A: bare steel B: insulating material 1-layered

C: Insulating material 2-ply

D: Insulating material 4-ply

E: Insulating material 6-ply

Claims

claims:

1. insulating material comprising an unconsolidated nonwoven fabric from a first high temperature resistant fiber, characterized in that it is reinforced with a second high temperature resistant fiber, wherein the two high temperature resistant fibers are clearly distinguishable from each other.

2. Insulating material according to claim 1, wherein both fibers have a melting temperature of at least 400 ⁰ C.

3. Insulation material according to claim 1, wherein the first and the second fiber differ due to their single fiber length.

4. Insulation material according to claim 3, wherein the first fiber has a greater single fiber length than the second fiber.

5. Insulation material according to claim 1, wherein the first and the second fiber differ due to their chemical composition.

6. The insulating material according to claim 1, wherein the first fiber is selected from the group consisting of glass fibers, basalt fibers, aramid fibers, carbon fibers, metal fibers, ceramic fibers, mineral fibers and oxidized polyacrylonitrile fibers.

7. The insulating material according to claim 1, wherein the second fiber is selected from the group consisting of glass fibers, basalt fibers, aramid fibers,

Carbon fibers, metal fibers, ceramic fibers, mineral fibers and oxidized polyacrylonitrile fibers.

8. insulating material containing a plurality of layers according to claim 1.

9. A process for producing an insulating material, wherein first an unconsolidated nonwoven fabric is provided from a first high temperature resistant fiber, characterized in that a. the unconsolidated web is sprayed with a dispersion of the second high temperature resistant fiber in an aqueous medium,

b. the aqueous medium is first removed mechanically and

c. the insulation material is dried.

10. The method according to claim 9, wherein subsequently a plurality of the individual layers are joined together.

11. Use of the insulating material according to claim 1 for sound insulation.

12. Use of the insulating material according to claim 1 for improving the acoustics.

13. Use of the insulating material according to claim 1 for thermal insulation.

14. Use of the insulating material according to claim 1 for the production of a composite material, characterized in that the

Insulating material is bonded to a layer of woven inorganic fiber and an inorganic shielding layer bonded directly to the woven inorganic layer.

15. Use of the insulating material according to claims 11 to 14 in a motor vehicle.

16. Use of the insulating material according to one or more of claims 11 to 15, wherein a plurality of layers of the insulating material are interconnected.