Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
  • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
  • B27N3/002—Manufacture of substantially flat articles, e.g. boards, from particles or fibres characterised by the type of binder
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
  • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
  • B27N3/08—Moulding or pressing
  • B27N3/086—Presses with means for extracting or introducing gases or liquids in the mat

Definitions

• the invention relates to a process for the production of moldings with a density of 0.15 g / cm 3 to 0.40 g / cm 3 at least from fiber or plant material obtained from renewable raw materials in the form of regrown, crushed raw materials and Tannin as a binder component without formaldehyde content.
• cellulose-based panels such as Wood chips, tannin-formaldehyde resin added.
• the tannin is that actual binder, while the formaldehyde serves as a crosslinker to the Tannin binding capacity to both increase and accelerate. Sheets produced in this way gradually outgas the formaldehyde, so that it can lead to health problems.
• DE 43 17 692 A1 discloses a method for producing molded parts from a mixture of fibrous materials in the form of wood chips sprayed with water and native starch from potatoes, corn or wheat as a biodegradable binder.
• the molded parts are formed by placing the mixture in a heatable press and pressing it into a plate at temperatures of up to 250 ° C.
• the moisture serves to facilitate the breakdown of the starch granules into a sticky, gel-like mass that connects the fiber materials.
• the pressing process at a pressure of 10 to 500 bar has high cycle times of 20 minutes and is therefore not very suitable for the industrial production of molded parts.
• the uncontrollable evaporation of the water can lead to a non-uniform digestion of the starch and thus to a reduced binding effect.
• the use of a press inevitably leads to high bulk densities of the molded parts of, for example, 0.5 g / cm 3 and more.
• the crushed fiber or plant material in the form of renewable raw materials and the tannin mixed together can for example either the tannin in aqueous solution on the fiber material be applied or the tannin on the pre-moistened fiber or Plant material can be sprinkled on as a powder.
• the whole thing should be good be mixed until the tannin on the fiber or plant material adheres evenly and an overall free-flowing mixture is formed.
• tannin is available on the market under the name "Phenotan AP" or the tannin available under the name "Fintan”.
• the mixture is then optionally added with a Crosslinking agent filled into a perforated form and compacted there.
• a Crosslinking agent filled into a perforated form and compacted there.
• the mixing process can also take place in the mold.
• the perforated Shape can be shaped as desired. You should advantageously at least have a movable wall by reducing the internal volume compacting the fiber or plant material-tannin mixture into the mold guarantee. Very light densifications on the order of for example, 1.05: 1 can already be achieved by shaking.
• the mixture in the perforated form is used to trigger a Thermal reaction with heated gas.
• the tannin open-minded and connects the fibers or parts of plants with each other.
• the Use of heated gas to trigger the thermal reaction has the great advantage that short cycle times of 1 to 2 minutes are achieved and Molded parts with wall thicknesses of well above the usual 10 to 12 mm can be produced. Because the heated gas that is in through the perforation the form in the mixture of fiber or plant material and tannin penetrates, penetrates the entire fiber or plant part volume and gives there quickly the heat required for the binding reaction.
• the method offers the advantage that without intermediate steps - such as e.g. the Preforming of mats or the like - molded parts made in a single mold can be. Due to the manageable number and simplicity of the Components and the easy controllability of the parameters, such as the small ones pressures required for compression and the relatively low temperatures of the heated gas, the process is further simplified.
• the molded parts produced by the process according to the invention have very low densities, namely 0.15 to 0.40 g / cm 3 , preferably 0.25 to 0.30 g / cm 3 , particularly preferably between 0.25 to 0.28 g / cm 3 cm 3 , compared to the conventionally produced molded parts such as press plates, since, in contrast to them, they were not pressed, but only compacted. Only low pressures, which are 0.1 to 0.2 MPa, preferably 0.15 to 0.16 MPa, are required for compression. Although the molded parts produced by the process according to the invention only have a fraction of the weight of the conventionally produced molded parts, they nevertheless have approximately the same thermal properties. As a result, the molded parts produced by the process according to the invention are far superior to the conventionally produced molded parts.
• Molded parts made from fiber or plant material made from renewable raw materials is good environmental sustainability. They are easy recycle as they are self-rotting. They also don't contain anything harmful additives such as formaldehyde.
• the compression is preferably carried out by reducing the internal volume of the perforated shape accomplished. Overall, care should be taken that a maximum compression of 4: 1 is not exceeded. Especially with Otherwise, molded parts with thicker walls can have the problem that the cellulose mixture is no longer homogeneous from the heated gas is penetrated and therefore also the thermal reaction to connect the Cellulose fibers do not run evenly everywhere. This can negatively affect the mechanical properties, such as the strength of the produced Impact molded parts.
• the temperature of the heated gas should not be 140 ° C exceed.
• Water vapor Temperatures between 115 ° C and 125 ° C, when using dry Air temperatures between 80 ° C and 100 ° C.
• the heated gas is preferably water vapor, dry one Air or carbon dioxide.
• water vapor is the heat transfer excellent.
• dry air or dry carbon dioxide that is Heat transfer not quite as good.
• the fiber or Plant mixtures begin when the gas is applied dry. Therefore, cycle times can be similarly short with all three gases become.
• the mixture is also in the perforated form after being exposed to a heated gas dried by exposing it to negative pressure.
• a pressure between 0.4 bar and 0.8 bar was proven.
• the negative pressure can for example via one or more vacuum openings in the perforated Shape.
• the drying times can be Reduce vacuum drying considerably. This is especially so when using it of water vapor important because of the water vapor registered additional moisture. This is advantageously done Vacuum drying immediately after applying gas, as the At the time the mold is still hot to aid drying.
• the fiber or plant parts can have a length between 1 and 70 mm. Depending on the size and complexity of the shape of the molded part to be produced and on the desired mechanical properties, the particle length of the starting material will be chosen to be short or long.
• the fiber or plant material should advantageously have a bulk density of 0.05 to 0.39 g / cm 3 .
• the binder or the mixture of fiber material and binder also at least one additive added.
• the additives should also have a the best possible environmental compatibility.
• a crosslinker such as e.g. Hexamethylenetetraamine (HMTA) added.
• a pH> 8 is preferred, particularly preferred a pH between 9.2 and 9.7.
• a enables better tannin digestion. This in turn increases it Tannin binding power.
• silicates in particular Water glass. They serve as reaction accelerators.
• a preferred recipe provides for the fiber or plant material 8 up to 12% by weight, preferably 10% by weight of the amount of fibers or plants as Binder are added.
• the binder formulation preferably has 80 up to 90% by weight of tannin powder, 4 to 8% by weight of HMTA powder and 7 to 12 % By weight of boric acid powder, the% by weight indicating the total amount of the binder.
• the boric acid powder becomes flame retardant and anti-fungal equipment of the moldings added. by virtue of the small amount of boric acid, based on the entire molded part, the Environmental impact not affected or only slightly affected.
• Binder dissolved in liquids and on the fiber or plant material sprayed on and mixed with it.
• the solvents as well as the Liquid content of the starting material of about 16% is used in the Dried again removed.
• the lower part 2 is a shape for shaping fiber or Plant material shown.
• the lower part 2 of the shape is characterized by this that it has a cavity forming a steam chamber 6a.
• the molded part 2 has a steam inlet 7a and a steam outlet 8a on.
• the lower part 2 is filled with a mixture 1 of plant material on the Basis of hemp shives between 10 and 20 mm in length and binding agent according to the recipe above.
• the mixture 1 fills the bottom part 2 completely and has a volume of 500 mm x 1000 mm x 85 mm.
• the tannin was in aqueous solution applied to the hemp shives.
• the one sold on the market under the name "Fintan” is also suitable Tannin.
• Mixture 1 was filled into the lower part 2 of the mold.
• the bottom surface 4a the lower part 2 is designed as a perforated plate. Through the perforation the plate 4a later becomes the steam inlet 6a into the steam chamber 6a let-in water vapor 5 can penetrate into the mixture 1.
• the upper mold part 3 onto the lower mold part 2 placed.
• the upper mold part 3 also has a steam chamber 6b and one Steam inlet 7b and a steam outlet 8b.
• the surface of the upper mold part 3, which is in contact with the mixture 1 is through the perforated plate 4b educated. Characterized in that the entire plate 4a or 4b is perforated ensures that the water vapor 5 from the vapor chambers 6a, b, as in Fig. 1c, can penetrate the mixture 1 as uniformly as possible.
• a faster drying can be achieved if after application with steam 5 and the same escaping the molding over a Vacuum opening in the upper or lower part 2,3 a negative pressure Order of magnitude of 0.4 bar to 0.8 bar. This should be immediate after the gas treatment so that the drying through the then still hot form is additionally supported. This will dry up reduced for several minutes.
• the molded part produced in this example is a plate a thickness of 30 mm. This simple shape was chosen because of the shape can be graphically represented simply to produce a plate. Of course the method according to the invention can also be used for more complex forms Use plates.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Wood Science & Technology (AREA)
• Forests & Forestry (AREA)
• Dry Formation Of Fiberboard And The Like (AREA)
• Paper (AREA)
• Cultivation Of Plants (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=7650145

Family Applications (1)

Country Status (3)

Cited By (5)

Families Citing this family (1)

Family Cites Families (8)

• 2000
  • 2000-07-24 DE DE10036193A patent/DE10036193A1/de not_active Ceased
• 2001
  • 2001-07-18 HU HU0103010A patent/HU223584B1/hu not_active IP Right Cessation
  • 2001-07-20 EP EP01117511A patent/EP1175981A3/fr not_active Withdrawn

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