DE20021096U1 - Natural fiber insulation fleece - Google Patents

Description

[Description]

The utility model relates to a natural fibre insulation fleece consisting of natural fibres and biodegradable binding fibres.

[State of the art]

Reducing carbon dioxide emissions is one of the most urgent tasks of our time. Saving energy is the most effective and cost-effective way to solve this problem. For the construction sector, the legislature requires effective heating systems combined with effective thermal insulation. Thermal insulation materials are offered in a wide variety and with different product properties for every application. They must meet requirements in terms of price, processability and functionality. Artificial insulation materials are still predominantly used. Ecological insulation materials offer alternative solutions. In recent years, in addition to traditional insulation materials such as mineral wool and foamed insulation materials, alternative/biogenic thermal insulation materials have become marketable due to increasing consumer awareness and environmental consciousness. The total market share of these thermal insulation materials is currently estimated at around 5%. Although this market share does not yet represent a mass market, there is enormous growth potential here. Among the renewable raw materials, in addition to cellulose (recycled paper), cork, wood, sheep's wool, cotton, straw or ceramic glass, the natural fibre flax/hemp - as a local product - has also become an interesting alternative for use as a thermal insulation material. Despite the diverse positive properties of commercially available flax/hemp insulation materials, one ecological weak point of fibre insulation mats is the addition of synthetic supporting fibres/binding fibres. Synthetic fibres are currently mixed into the natural fibres to strengthen the flax/hemp insulation mats. Polyester bicomponent fibres are important for the insulation material sector.

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with a side-by-side structure. After thermofusion, they give the insulation material resilience/elasticity with the appropriate strength. The proportion of synthetic material is generally 10-20% and depends on the quality of the natural fibers used or the requirements profile of the insulation product. However, the use of such materials contradicts the trend to minimize or eliminate environmentally harmful additional products and the sales argument of offering the building product "pure nature". Another way of strengthening the fleece is by spraying a thermally-mechanically broken down potato starch (Flachshaus - company brochure). The disadvantage of this process is the complex cleaning process of the system technology.

DE 195 17 763 Al discloses a composite material based on cellulose acetate and reinforcing natural cellulose fibers. This material can also be used as an insulating material. Cellulose acetate fibers are unsuitable for flexible, pressure-free use due to their high softening temperature. Processing under pressure takes place at temperatures of around 220 to 280 ⁰ C. The prerequisites for the biofibers to be suitable for use are thermoplasticity, spinnability, thermal stability, flowability, and the ability to be processed into pile fabrics and solidified nonwovens.

[Task of the invention]

The aim of the invention is to develop thermal insulation fleeces based on CO ₂ -neutral, renewable raw materials using new thermoplastic, biodegradable polymers as binding components. The ecological insulation materials should be easy to produce in a conventional manner using standard industrial plant technology and at the same time

have sufficient strength, good flexibility, low thermal conductivity.

The aim is to develop novel, fully biodegradable insulation materials with high performance for the construction sector, especially for walls, ceilings, roofs, between rafters and beams.

The problem is solved surprisingly simply and in good product quality by the fact that these consist of 80-90 mass% natural fibers, such as flax, hemp, sisal, jute, coconut, kenaf, nettle, ramie and/or other cellulose fibers and 10-20 mass% biodegradable binding fibers from the group of aliphatic/aromatic copolyesters and/or aliphatic homopolyesters and/or starch acetates and/or cellulose diacetates and/or starch blends, whereby these blends are to be understood as starch with biodegradable synthetic polymers in the sense of the invention, and/or biotechnologically produced polymers from the direct fermentation of the sugar. Advantageous embodiments are mentioned in subclaims 2 to 5.

0 The use of biodegradable binding components in the insulation fleece, with the aim of obtaining a completely natural building product, is a promising alternative to the synthetic binding fibers used to date, with the possible addition of additives such as fire retardants. The granules of the biotechnologically produced polymers, such as BIONOLLE, SCONA-CELL or Eastar - Bio Copolyester, are spun into filament yarn, processed as binding fiber and mixed into the natural fiber fleece as a strengthening component using standard industrial technology 0 and adapted technology. The selected biopolymers can be spun using standard industrial extruders (e.g. from Randcastle and FEP Polymertechnik). Spinning can be carried out in very different fineness ranges of less than 50dtex. With regard to

a low thermal conductivity, bulk densities between 30 and 60 kg/m ³ and a fleece strength of >10 tnN/mm ^2. The starting material is, for example, a largely homogeneous, fine-fibered, well-roasted flax with an average fineness of 45 dtex. It is mixed with the binding fibers selected according to the invention with different staple fiber fineness and length and thermally bonded. In addition to the binding fiber origin, fineness and length, the amount used and the thermofusion technology are varied. The work is supplemented with various carrier fibers with a coarse fiber fineness (pure green flax, mixed with roasted flax and/or hemp or other natural fibers).
The filament yarns are first cut into defined lengths in previously braided bundles on the Pierret cutting machine. Cutting is carried out while the yarn is wet - especially for synthetic filament yarns - to avoid sticking of the cutting edges. The following technological process on a laboratory scale can also ensure the even distribution of the staple fiber mixture in the natural fiber: - pneumatic opening of the natural fiber

- manual mixed bed laying,

- Premixing of the mixed bed in the fibre opener,

- Mixing/dissolving and fibre parallelisation on the carding machine, - Cross-panelling, pile layers using panelling machines.

To produce the insulation fleece, the material can be fed from a random fleece machine or a carding machine for consolidation. The fiber web (e.g. mass per unit area 0 3 50g/m ² on a laboratory scale) mixed/dissolved and paneled on the carding machine is then removed in a discontinuous process and then fed to the dryer.

The fleece is bonded using thermofusion - a standard insulation fleece bonding technology - at

a dryer. The dryer works according to the principle of ventilation/ventilation/spray intensity, thermofusion temperature and screen belt speed can be varied. The natural fiber fleece containing binding fiber is heated to the melting or softening temperature of the binding fiber, the binding fibers melt or soften and more or less enclose the carrier fiber and, after cooling, lead to an adhesive, purely mechanical anchoring of the components to be connected. Since the mixture distribution between binding fiber and natural fiber is essential for good fleece consolidation, various mixture variants or mixture technologies are possible.

The thermal property investigations focused on measurements of thermal stability such as melting/softening point, tempering and curing processes and viscosity investigations. They served to gain knowledge of the technological properties of the materials and enabled the selection for use as binding fibers. Microscopic investigations were carried out to characterize the binding behavior of natural fibers/biopolymers. Biopolymers exhibit considerable differences in melting and softening behavior depending on their polymeric origin.
However, in order to ensure good adhesion to the carrier fiber, the binding fiber must be sufficiently fluid during the heat treatment; only then is the flow around the carrier fiber guaranteed. After cooling, an adhesive, purely mechanical anchoring of the components to be connected occurs. Figures 1 and 2 show the bonding points that form on the carrier fiber. Depending on the type of biopolymer or its material specifics, bonding points of different sizes and shapes form.

The binding points - formed by Bionolle - are finely distributed (already at a temperature of 120 ⁰ C) in the fleece

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The Sconacell bonds with the carrier fibers, forming relatively large bonding points, which suggests only moderate flowability. The polymer is less well distributed between the carrier fibers and therefore flows around them less intensively.

A completely biogenic thermal insulation material, not pressure-resistant, for use in areas such as walls, ceilings and roofs (application type W) and/or for use in areas such as insulation between rafters and beams (application type WL) with a fleece strength of > lOmN/mm ² (according to DIN 18165T1) , a thermal conductivity of &lgr; _lotr . 0.037 W/mK, is obtained with the following specification: Biodegradable binding fiber preferably made of synthetically produced polymers
- Application quantity 20%, fiber length 50mm, staple fiber fineness <. 5dtex
Thermofusion temperature <. 160 ⁰ C
Carrier fibre roasted flax 45dtex, density 30...60kg/m ³

[Examples]
example 1

Flax fibers with a fineness of 45 dtex were processed into a thermal insulation fleece with a density between 30 and 60 kg/m ³ in a mixture with a biodegradable binding fiber. An aliphatic homopolyester was used as the biodegradable binding fiber.

Recipe
Biofiber - BIONOLLE 1020

Biofiber use amount of 20%
Biofibre length 50mm
Biofibre fineness 5dtex

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The flax material is opened pneumatically, mixed with the organic fiber, carded and layered using a paneling machine to form a mixed fiber pile. The fiber pile mixed and paneled on the carding machine is solidified using thermofusion at a temperature of 120 ⁰ C.

A fleece strength of 1/q 7mN/mm ² /2 0mN/mm ² was achieved. The thermal conductivity was Lambda _1O tr. 0.037W/mK.

Example 2

Flax fibers with a fineness of 45 dtex and a density between 30 and 60 kg/m ³ were mixed with a biodegradable binding fiber to produce a thermal insulation fleece. An aliphatic homopolyester was used as the biodegradable binding fiber.

Recipe

Biofiber - BIONOLLE 1020
Biofiber use amount of 10%
Biofiber length 2 0mm
Biofibre fineness 5dtex

The flax material is opened pneumatically, mixed with the organic fiber, carded and layered using a paneling machine to form a mixed fiber pile. The fiber pile mixed and paneled on the carding machine is solidified using thermofusion at a temperature of 140 ⁰ C.

Example 3

A flax blend with 50% green flax with a fineness of 87dtex and 50% roasted flax with a fineness of 45dtex

DE 200 24 096 Ui

is mixed with the biodegradable binding fiber and solidified into an insulating fleece.

Recipe
Biofiber - BIONOLLE 1020

Biofiber use amount of 20%
Biofibre length 50mm
Biofibre fineness 5dtex

The flax material is opened pneumatically, mixed with the organic fiber, carded and layered using a paneling machine to form a mixed fiber pile. The fiber pile mixed and paneled on the carding machine is solidified using thermofusion at a temperature of 140 ⁰ C.

Due to the currently high material price of biopolymers, a reduction in the amount used is interesting for the potential user. The example with the binding fiber Bionol-Ie shows that a reduction in the amount used leads, as expected, to a loss of strength. The use of only 10% binding fibers results in a reduction in strength of approx. 30%. Nevertheless, the values determined are within the approved range. The options of increasing the thermofusion temperature, the residence time or the use of a finer binding fiber would be alternatives for improving the fleece strength.

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[Attached drawings]

Number of attached drawings: [2]

1 Bionolle/Flax

2 Sconacell/Flax

Claims (6)

1. Natural fiber insulation fleece consisting of natural fibers and binding fibers, characterized in that the natural fiber content is 80-90 percent by mass and the binding fibers are biodegradable, having a content of 10-20 percent by mass and consisting of aliphatic/aromatic copolyesters and/or aliphatic homopolyesters and/or starch acetates and/or cellulose diacetates and/or starch blends, wherein these blends are starch with biodegradable synthetic polymers, and/or biotechnologically produced polymers from the direct fermentation of sugar. 2. Natural fiber insulation fleece according to claim 1, characterized in that the fiber length of the biodegradable binding fibers is preferably 20 mm to 50 mm. 3. Natural fiber insulation fleece according to claim 1 and 2, characterized in that the fiber fineness of the biodegradable binding fibers is preferably below 50 dtex. 4. Natural fiber insulation fleece according to claims 1 to 3, characterized in that the natural fibers are flax, hemp, sisal, jute, coconut, kenaf, nettle, ramie and/or other cellulosic fibers. 5. Natural fiber insulation fleece according to claims 1 to 4, characterized in that natural colorants and/or naturally degradable additives, such as fire retardants, antimicrobial finishes and/or anti-mold finishes, are added. 6. Natural fiber insulation fleece according to claims 1 to 5, characterized in that the insulation fleece is used in the construction sector, in the packaging sector or in the automotive interior.