DE19757418B4 - Insulating, filling or packaging material of plant material, process for their preparation, and moldings produced therefrom - Google Patents

Abstract

An insulating, filling or packing material made of plant material is described which contains or consists of the aboveground biomass of bulrushes, the aerenchymal structure of which is still largely preserved, characterized in that the leaves or leaf parts of bulrushes are continuous in the longitudinal direction or only in the area of the Outer skin are severed one or more times. Also described are moldings obtainable therefrom, in particular insulating elements.

Description

The invention relates to insulation, filling or packaging materials from plant material, process for their preparation, and moldings produced therefrom.

There are various plant materials known that can be processed into insulation materials, insulation boards or lightweight panels and then have more or less good thermal and sound insulation properties; otherwise they are subject to such defects that they could not prevail over the partially ecologically and health-critical synthetic insulating materials on the market.

In some cases, they consist of raw materials that are only limited available and / or need long transport routes, such as cork, coconut fiber and reeds, some of the raw materials must be prepared consuming, such. B. in the production of wood fiber boards. Many insulating materials have due to the fabric structure of the starting material and / or due to the manufacturing process only moderate insulation properties, eg. B. wood wool lightweight panels, reeds and straw plates. The mentioned deficiencies result in high consumer prices.

Furthermore, from the DE 812 779 B a method for the production of components in the form of sawable blocks of organic fillers and mineral binders and water glass known, in which a larger volume of fragments of tubular plants, such as cattail fracture, Binsenbruch, poppy seed fracture, pond piston fracture or other marsh plants of reed-like appearance with a small amount of waterglass solution treated and silicified, whereupon the mass after thorough drying with small amounts of mineral binder, especially cement, and clay intimately mixed and compacted under high pressure (more than 5 bar) to about the tenth part of the initial volume, the cement during the pressing process is brought to the ligation.

Cavities and thus a certain insulating effect are achieved in this process mainly by partially pressure-stable tubular plant materials are used. The fabric structure of the less pressure-resistant sheets, z. As of cattail, poppy, plunger u. Like. Is completely destroyed by the high pressure.

The DE 43 33 758 A1 relates to an insulating device for heat and / or sound insulation, consisting of a fire-retardant, loose or processed to a non-woven, preferably mat-shaped composite of natural fiber such as flax, cotton, coconut, sisal, wool, biomass such as reeds, typha, straw or other plants ,

The patent AT 351 994 B relates to an insulating, filling or packaging material made of plant material according to the preamble of claim 1.

The invention has for its object to provide from renewable, domestic plant raw materials insulation, filling and packaging materials and moldings produced therefrom, which have a similar good insulation value as synthetic insulation materials and their production, use and disposal are simple and safe for health and ecology , Furthermore, the task was to find a material that has a certain elasticity in addition to its good insulating properties, so that it is also suitable as a packing material with insulating properties.

The invention is thus an insulation, filling or packaging material from plant material, which contains or consists of the above-ground biomass of cattail whose Aerenchymstruktur is still largely preserved, characterized in that the leaves or leaf parts of cattail in the longitudinal direction continuously or only in the region of their outer skin are severed once or several times.

Cattail (botanical name: Typha) with their most common species Thypha latifolia L. and Typha angustifolia L. are well cultivated wild plants in our climate, which ensure a high yield (20-40 tons per year dry matter / ha.) And an environmentally friendly cultivation enable. They can be easily cultivated on wetlands, whereby the cultivation can be linked with measures for water protection. They are able to bind excess nutrients from waste water and surface water so that they can be used in wetland plants. Also, they can be used for the utilization and stabilization of rewetted peat soils.

The lanceolate leaves of the indigenous species Typha angustifolia or latifolia, which grow up to 3 m long, grow as leaf bundles directly from the rhizome. The leaves have a crescent-shaped cross-section. The cell tissue of the outer skin is traversed in the longitudinal axis densely covered with bast fiber Leitbündeln and pure raffia strands. The thin outer skin is stiffened by an inner chamber system consisting of longitudinally parallel and transversely arranged partitions. The longitudinal septa consist of closed-cell tissue, whereas the transverse septa (diaphragms) are permeable. They resemble a net with predominantly triangular and quadratic stitches. Between the partitions there are air chambers (Lakunen), which in adult leaves have a length of 3 to 4 mm and a width of 2 to 3 mm. The interior of the lacunae is filled with a fine filamentous sponge fabric, the aerenchyma or aeration tissue, which occupies most of the leaf volume and causes the good insulation properties.

The invention is based on the finding that insulating, filling or packaging materials with good insulating properties can be obtained when the aerenchymal structure of the cattail leaves is still largely preserved. The aerenchyma is an elastic fabric whose elasticity is irreversibly lost when the cattail leaves are transversely to the blade direction at a higher pressure, e.g. B. of more than 4 to 5 bar, are exposed. This fact was invented by the inventor of the DE 812 779 B not recognized, since a compression under a pressure of about 5 atm and more, a volume reduction by a factor of 10 occurs. Microscopic examinations of specimens prepared in this way showed that the chamber system and the pore framework of the aerenchyma of cattails were crushed. However, even a partial regeneration was no longer possible since the water glass and the hydraulic binder prevented expansion after the molding had hardened. The specific gravity of the specimens was at least 1100 kg / m ³ , which corresponded to the specific gravity of the currently used bricks. A high insulation effect can not be achieved with it. From an actual insulation or insulation so it can not be spoken, possibly of a lightweight construction element.

The fact that the inventor of the DE 812 779 B the importance of an intact Aerenchymstruktur has not recognized, it also results from the fact that in addition to cattail other tubular plants without a sponge-shaped aerene, z. B. reeds were used. By the selected process technology, in particular by the high pressures and the resulting compaction to about one-tenth of the initial volume just those plant tissues are destroyed, which would be particularly well suited for the production of insulation materials.

The insulating, filling or packaging materials according to the invention are preferably in the form of leaves or leaf parts with a maximum length of 15 cm, preferably of a maximum of 2 to 6 cm. The particle volumes of the comminuted material are between about 0.01 and 15 cm ³ , preferably between about 0.5 and 5 cm ³ .

Since the leaves or leaf parts have a crescent-shaped cross-section, it has proved to be useful to sever the outer skin one or more times in the longitudinal direction. By this measure it is achieved that the particles lie flat on one another, so that the volume between the particles is minimized. This treatment does not damage the aerenchyma. Typically, the severing of the outer skin is effected by the blade sections are sent after longitudinal chopping by parallel cutting discs, wherein they are divided into strips with a width of about 1 to 10 mm. By this measure, one achieves especially a relaxation and easier handling of the material. The sickle shape of the leaves is flattened; As a result, the particles lie closer together, and the risk of cavitation between the leaf parts decreases. Furthermore, lower pressures can be used in the subsequent shaping.

It is also favorable here that Typhablattmasse is largely SiO ₂ -free and therefore can be broken down precisely with sharp cutting tools to the desired shape particles without the cutting tools are dull prematurely.

According to a particular embodiment, only the outer skin is severed by the cutting discs, wherein the leaf parts remain connected to each other via the aerenchymal tissue. In this way, the tension in the outer skin is also eliminated, resulting in larger, flat particles, so that the free space between the particles is reduced. In addition, less aerenchymal tissue is exposed, which reduces the penetration of binders into the pores in the subsequent production of moldings. Apart from cutting discs, the leaves or the outer skin of the leaves can also be severed by cutting rollers, sawmills and by means of mass or light rays.

Another way to adapt the particle shape of the required structure is to soften sheet parts by a steam or liquid treatment, so that also in this way the crescent-shaped cross section of the leaves is flattened.

Finally, there is the possibility of dividing the lower ends of the bundles of leaves, as they are slightly glued, out of the rhizome, not to break them down into single leaves, but to break up the closed bundles by dividing them into suitable larger leaf packets.

The insulating, filling or packaging materials according to the invention can be a mixture of particles of different sizes and shapes. The smaller particles fill the voids between the larger particles, improving the insulation effect.

According to a further preferred embodiment, the outer skin and / or the aerenchyma is impregnated. The impregnation can be effected by incorporation of a pulverulent impregnating agent or with an aqueous solution of the impregnating agent. The impregnation of the inner surface is carried out either by penetration of the dry particles into the sponge structure of the aerene chyme or by compression of the elastic leaf tissue and the subsequent relaxation in the impregnating liquid. The aerenchym sucks itself like a sponge. A fire, decay, pest or similar protective treatment is therefore much more effective than the purely superficial equipment of closed-cell plant tissues. The excess impregnating liquid is squeezed off, whereupon the aerenchyma returns to its original shape due to its elasticity. The impregnation treatment may be followed by drying if desired.

The invention further relates to molded articles, in particular insulating elements, which contains a bonded insulating material, as described above. In the molded body, the insulating material can be present in different sizes or shapes. The larger particles provide structural integrity and low density of the molded articles. The smaller particles cause the material to close the molding compound, so that no larger cavities exist that could worsen the insulation values.

The moldings according to the invention preferably contain, in addition to the insulation particles, a binder, wherein a low pressure transversely to the sheet direction (fiber direction) is sufficient for connecting the insulation particles. The maximum applied pressure across the sheet direction is about 2 bar, preferably at most 1 bar, since the aerenchyma, as already said, is irreversibly destroyed at higher pressures. In general, already sufficient pressures of 0.2 to 1 bar, preferably pressures of 0.4 to 0.6 bar are applied. The pressures also depend on the desired density of the insulating particles.

In contrast, higher pressures can be applied in the direction of the blade axis without destroying the aerenchyma. In the sheet direction, the insulating particles are therefore much more stable than transverse to the sheet direction. The stability of the up to 3 m high leaves is based on the combination of bias of the cover layers in the direction of the plate axis and the elastic filling of the core layer with a foam fabric, which is divided into chambers along the plate axis. This circumstance characterizes these static properties and thus the mechanical strength. Cattail leaves are, as far as their static system is concerned, to a certain extent "tires" with the peculiarity of a high pressure stability of about 20 bar in the direction of the blade axis and reversible elastic behavior transversely thereto in the range of 0 to about 3 bar.

Further details are given below in connection with insulation boards.

As binders, organic or inorganic binders can be used. The inorganic binders include, for example, water glass, sulfite waste liquor, gypsum, loam, lime-silica sand mixtures or hydraulic binders such as cement, in particular Sorelzement (magnesia cement), which is obtained by stirring burned magnesium oxide with a MgCl ₂ or MgSO ₄ solution. These inorganic binders can be used with low pressures across the direction of the sheet so as not to destroy the aerene-like structure.

The organic binders are dispersed or dissolved either in water or in an organic solvent, the use of aqueous binders being preferred for environmental reasons. Small amounts of binder are sufficient, especially if the crescent-shaped leaf structure has been flattened by one of the treatments indicated above. Examples of binders are glue, paste, synthetic resin adhesive, hot melt adhesive, casein glue, gum arabic, latex and rubber adhesive, acrylic dispersion adhesive, etc.

The invention also includes molded articles with a sandwich structure, the individual layers of which differ from each other in terms of degree of compaction, particle size or shape and / or by the nature or amount of the binder. In general, the sandwich-type shaped bodies consist of one or two more compacted cover layers and a lower-density core layer.

The fibers of the insulating particles in the core layer are perpendicular to the surface of the molding, parallel thereto or randomly aligned, depending on the requirements of the statics of the molding; the cover layer (s) is (are) pressed onto the surface of the core layer. The cover layer (s) is (are) generally bonded to the core layer with a binder and is (are) pressed onto the core layer at a pressure of about 1 to 10 bar, preferably about 3 to 5 bar.

The individual layers, in particular the cover layer (s) of the sandwich structure, may also consist of materials other than tubular bulbs or also of compacted tubular piston particles. Other materials for the cover layer (s) are, for example, wood veneers, films, Panel materials, paper or cardboard, mortar, paint or textile materials.

The invention is illustrated by the following examples.

example 1

Production of an insulating material

Typha leaves are cut longitudinally with a cutting roller into strips about 3 mm wide. The strips are then cut by a cross-cutter into particles of about 3 to 5 mm in length. After both cuts, the aerenchyma is still intact.

The particles are in a drum mixer with a finely ground mixture of ammonium sulfate (14 wt .-%, based on the organic material) as a flame retardant and sodium borate (0.1 wt .-%, based on organic material) as an antifouling and fungicidal agent, mixed until the powdery mixture is completely taken up by the aerenchyma of the leaf particles.

The impregnated material has a bulk density of about 40 kg / m ³ and a specific thermal conductivity (λ) of about 0.035 watts / (K · m).

The particles are used as injection or bulk insulation in cavities of both sides interconnected constructions or in hollow bricks, wherein the injection pressure is sufficient that the mass of the particles does not collapse in shocks, since the particles have good permanent elastic properties. In addition, the particles have a good flowability.

In the flame test, the material almost meets the requirements of fire class B I.

The insulation particles prepared according to Example 1 can also be used as packaging materials for dishes and machine parts, in which case the impregnation can be omitted. Preferably, however, larger particles having a volume of about 5 to 20 cm ³ are used as packaging materials. When used as packaging material, the material can be composted at the recipient.

Example 2

Production of an insulating board

For the production of an insulating board, which is suitable for thermal and impact sound insulation, a mixture of cut Typha leaves with three different particle sizes is used:
40% large particles of only cross-sectioned leaf bundle sections from the lower end of the Typha leaves (length 3 to 5 cm, volume about 20 cm ³ );
40% average particles obtained by slitting the Typha leaves in strips of about 1 cm with cutting rollers and then dividing them into sections of about 1 cm in length (particle volume about 5 cm ³ );
20% small particles obtained by division into strips about 0.3 cm wide and about 0.3 cm long (particle volume about 0.5 cm ³ ).

By using a mixture of different particle sizes, the remaining voids between the larger particles are filled up with the smaller particles, making the plate more compact and harder.

This mixture is mixed dry in a drum mixer with the finely ground ammonium sulfate / sodium borate mixture of Example 1 in the weight ratios specified there until the powdery material is completely absorbed by the aerene chemistry of the leaf particles.

The mixture thus pretreated is mixed in a gluing drum with about 35% by weight of a water-emulsified latex adhesive (solids concentration 30%). The mixture is shaken into perforated molds measuring 2 × 1 m and pressed at a pressure of 0.25 bar to a layer thickness of about 6 cm and dried by blowing preheated air. In this way, the core layer is obtained.

The cover layers are obtained as follows.

From the upper leaf third of Typhapflanzen with a lower Aerenchymvolumen than in the lower part are cut with cutting rollers about 2.5 mm wide longitudinal strips from which then about 10 cm long pieces are cut. The treatment of these pieces with ammonium sulfate, sodium borate and latex adhesive takes place as in the core layer.

With a thorn roller, the mixture of sheet strips is randomly ejected to a about 4 cm high fleece, pre-dried with hot air and then pressed between pairs of rolls, perforated strips or perforated rigid plate shapes under pressure of about 10 bar to plates with a thickness of about 3 mm.

After curing, the cover layers are bonded to both sides of the contact bonding method (spraying the latex on the surfaces), drying and compression at a pressure of about 10 bar with the core layer, formatted and on the four end faces with two grooves and provided two springs. On the pretreated end faces corresponding preformed cover layer strips are glued.

The insulation board produced in this way has a specific thermal conductivity (λ) of 0.040 watt / (K · m) after storage at normal air humidity. It meets the standards for fire resistance according to B II; It is resistant to rotting and can be used as a footfall insulation board. Both the core layer and the cover layers are isotropic, i. h., there is no preferred machining direction.

Example 3

Production of a sandwich plate

A sandwich panel, which is suitable for thermal and acoustic insulation and which has a high compressive strength and flexural rigidity, is manufactured as follows:
To prepare the core layer are in a U-shaped frame (width 2 m, height 1.20 m, depth 60 cm), glued with Sorelzementkleber glued lower third of the cattail mass as a bundle of leaves (length about 60 cm) aligned in a timely manner (because of short setting time of the sorel cement); when the rack is filled, the parallel aligned sheets of sheet are compressed from above with a flat plate under a pressure of about 0.25 bar to a height of 1.0 m, wherein substantially only the free space between the sheet strips disappears, while the Aerenchymvolumen is not significantly reduced. The obtained package is allowed to set and cuts perpendicular to the blade axes plates with a thickness of about 7 cm. The ratio between binder and leaf mass (in each case based on the dry mass) is about 2: 1.

The resulting panels are first (if necessary, after formatting or assembly to larger structures) placed on a flat pressure-resistant surface. Then the cover layers of the randomly arranged particles of Example 2 are applied successively, but instead of the latex adhesive, they were bonded to the aforementioned sorel cement binder (weight ratio of binder to leaf mass = 5: 1, in each case based on dry substance). The cover layer is pressed onto the core layer at a pressure of about 5 bar.

After curing, the second cover layer is applied in the same way to the back of the core layer.

The plate obtained by the method described above has a density of about 180 kg / m ³ , a specific thermal conductivity (λ) of 0.045 watts / (K · m), a compressive strength of about 5000 kg / m ² and a flexural strength of about which corresponds to a 20 mm thick Nadelhholzbrettes.

Without the additional equipment of fire-retardants, the panel complies with fire-safety requirements according to Class B II, as the sorel cement acts as a fire-retardant. The rotting protection is sufficient.

Example 4

Production of a sandwich plate

Core layers are prepared according to the procedure described in Example 3, but with an organic binder (latex adhesive, 20% by weight of the sheet material, in each case based on dry matter). The core layers of 40 mm thickness thus prepared are impregnated with an aqueous solution of ammonium sulfate and sodium borate (weight ratio as in Example 1) by spraying this solution on both sides of the plate-shaped core layer. After drying the core layer, top layers of plywood having a thickness of about 6 mm are glued under a pressure of about 5 bar and using polyurethane adhesive.

The sandwich panel obtained in addition to a good thermal conductivity (λ) of 0.045 watts / (K · m) and the good sound insulation properties of an 8 cm thick mineral fiber insulation board of about 300 kg / m ³ , especially a very high flexural rigidity, according to a Softwood board of 45 mm thickness (grade II) with low weight (about 120 kg / m ³ ). The plate is suitable for example for the production of door leaves, wall panels, table tops and the like.

Example 5

Production of an insulating board

Layers are produced as the cover layers described in Example 2, with the difference that they are not compacted at 10 bar to 3 cm, but at 1 bar to 8 cm. From contact adhesive four layers of this material are added to a plate. This is particularly suitable for the insulation of impact sound.

Example 6

Production of a form stone

A shaped block in the form of a hollow brick is produced using the non-impregnated insulating particles of Example 1 by mixing with an aqueous clay suspension (weight ratio of insulating particles: clay, in each case based on dry matter = 1: 5; concentration of the clay suspension: 40% by weight).

From the mixture hollow blocks with the dimensions 49 × 24 × 10.8 cm with a wall thickness of about 6 cm are produced by extrusion, which are then dried.

By using clay as a binder in a larger amount, although the thermal conductivity properties slightly deteriorate (λ = 0.055 watts / (K · m), but the molded block has a surprisingly high compressive strength.

The cavities of the molded block can be filled with the insulating particles of Example 1.

Claims (18)

Insulating, filling or packaging material of plant material, which contains or consists of the above-ground biomass of cattail, whose aerenchymal structure is still largely preserved, characterized in that the leaves or leaf parts of cattail in the longitudinal direction continuously or only in the region of its outer skin or severed several times. Insulating, filling or packaging material according to claim 1 in the form of leaves or leaf parts with a maximum length of 15 cm, preferably of at most 2 to 6 cm and a particle volume of about 0.01 to 15 cm ³ , preferably from about 0.5 up to 5 cm ³ . Insulating, filling or packaging material according to claim 1 or 2, characterized in that the outer skin is softened by a steam or liquid treatment. Insulating, filling or packaging material according to one of claims 1 to 3, characterized in that it represents a mixture of particles of different size and shape. Insulating, filling or packaging material according to one of claims 1 to 4, characterized in that the outer skin and / or the aerenchyma are impregnated. Insulating, filling or packaging material according to claim 5, characterized in that the impregnation has been carried out by incorporating dry particles into the aerene chile or by pressing, absorbing an impregnating liquid and pressing off the excess impregnating liquid. Shaped body, in particular insulating element, containing a bonded insulating material according to one of claims 1 to 6. Shaped body according to claim 7, characterized in that the insulating material particles have been pressed using a binder at a low pressure transversely to the sheet direction. Shaped body according to claim 7 or 8, characterized in that it has been obtained using a pressure transversely to the sheet direction of a maximum of 2 bar, preferably of at most 1 bar. Shaped body according to one of claims 7 to 9 with a sandwich structure whose individual layers differ from each other in terms of degree of compaction, particle size or shape and / or by the nature or amount of the binder. Shaped body according to claim 10, characterized in that the fibers of the insulating particles in the core layer are aligned vertically, horizontally or randomly to the surface of the shaped body and the cover layer (s) is pressed onto the surface of the core layer (are). Shaped body according to claim 11, characterized in that the cover layer (s) is (are) bonded to the core layer with a binder and is pressed onto the core layer at a pressure of about 1 to 10 bar, preferably of about 3 to 5 bar ( are). Shaped body according to one of claims 10 to 12, characterized in that the cover layer (s) of the sandwich structure consist of materials other than cattails or of differently densified cattail leaf mass particles. Shaped body according to claim 13, characterized in that the other materials made of veneer wood, films, board materials, paper or cardboard, mortar, paint or textile materials. Process for the production of insulating, filling or packaging material from plant material containing or consisting of the above-ground biomass of cattail whose aerenchymal structure is still largely preserved, characterized in that the leaves or leaf parts of cattail in the longitudinal direction continuously or only in the region of its outer skin be severed one or more times. A method according to claim 15, characterized in that leaf parts are produced with a maximum length of 15 cm, preferably of at most 2 to 6 cm. A method according to claim 15 or 16, characterized in that leaf parts are produced with a particle volume of about 0.01 to 15 cm ³ , preferably from about 0.5 to 5 cm ³ . Method according to one of claims 15 to 17, characterized in that the severing is carried out using strips of parallel cutting into strips with a width of about 1 to 10 mm.