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
  • B27N7/00—After-treatment, e.g. reducing swelling or shrinkage, surfacing; Protecting the edges of boards against access of humidity
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21J—FIBREBOARD; MANUFACTURE OF ARTICLES FROM CELLULOSIC FIBROUS SUSPENSIONS OR FROM PAPIER-MACHE
  • D21J1/00—Fibreboard
  • D21J1/08—Impregnated or coated fibreboard
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21J—FIBREBOARD; MANUFACTURE OF ARTICLES FROM CELLULOSIC FIBROUS SUSPENSIONS OR FROM PAPIER-MACHE
  • D21J3/00—Manufacture of articles by pressing wet fibre pulp, or papier-mâché, between moulds

Definitions

• the invention relates to a process for the properties sheep + sverêtung, slurry fiber, then wetted in particular water resistance and mechanical strength of from cellulosic press-molded parts produced in which exposed the mold parts to a vacuum using a suitable flowable resin, subjected to a pressure increase and then cured.
• such molded parts are produced in substantial quantities, in some cases their surface properties are desirably rounded off by surface impregnation with synthetic resins, and are used technically wherever the final properties that can be achieved with them are used the requirements set must be brought into line.
• Such molded parts are currently used in a wide range of applications. as a carrier for interior parts in motor vehicle construction and as a material for loudspeaker membranes.
• the goal is to improve the properties of molded fiber parts in order to achieve the level of properties of molded plastic parts and at the same time to use the known high proportion of available and renewable raw materials.
• the invention is based on the object of specifying a more economical impregnation process for fiber molded parts, which is characterized by better resin utilization and short-term impregnation treatment, with no drop and runner formation occurring on the surfaces of the impregnated molded parts.
• the object is achieved by using the method according to the invention, because the impregnation time can be reduced to a duration of only minutes.
• the resin which is still separated from the wetted molded parts under vacuum and is therefore not fully reacted, is available for subsequent further impregnations, which greatly increases the economic yield.
• liquid isocyanate group-containing mono-, oligo- and / or polymers with constituents of wood and / or cellulose constituents can react chemically to form solids and, together with them, harden process, such as in - "Polyurethanes in the fifth decade" - v. G. Oertel KUNSTSTOFFE 1/81 - mentioned, without any additional component such as a polyol.
• the existing relatively high gas and / or liquid absorption and permeability is typical for the fibrous molded articles mentioned.
• the aftertreatment of fiber molded parts is accordingly carried out with liquid resins containing isocyanate under conditions which take advantage of the liquid absorption of the molded parts and at the same time reliably preclude the contact of the molded part constituents reacting with isocyanate groups with the resin wherever outside the part the storage stability of the liquid phase must be preserved.
• the essence and content of the invention therefore consists in an economical process which ensures the penetration of fiber molded parts with a suitable isocyanate resin, thereby reliably precluding the contact of ingredients of the molded parts with resin components which have not penetrated into them.
• the penetration of the resin content is cured by chemical reaction with the components' ingredients.
• the reaction products attach themselves to the fiber structure, largely fixing and sealing it.
• a non-toxic isocyanate resin which is matched in viscosity, reactivity, NCO content and chemical structure to the liquid absorption and the content of reactants of the fiber molding and the desired end properties, in such a way that the resin preferably already contains degassed molded parts are brought into contact for wetting and penetrates into the molded parts by increasing the pressure.
• the molded parts can be in the same container above an isocyanate resin liquid level. After reaching the desired vacuum in the container, about 30-100 torr, the resin floods the parts. The fiber molded parts are still separated from excess liquid under negative pressure after the surface-attached resin has run off. When the pressure is increased, preferably in the range from atmospheric pressure to about 20 bar, then only the quantity of the resin liquid film still adhering to the parts penetrates and drip and runner formation are excluded.
• the curing can then take place in a separate container at elevated temperature.
• these processes take place in a rotatable and / or tiltable vacuum and / or pressure vessel, with the vessel being rotated through 180.degree.,
• the molding process for molding molded parts in an isocyanate resin bath and the reversal or further rotation of the separation of the two Components takes place.
• the fibrous molded parts treated with the one-component isocyanate resin become the usual, possibly accelerating the hardening process exposed, while the unused portion of the resin remains available for repetitions of the process and is replenished with fresh produce if necessary.
• the fibrous material can be enriched with mechanically higher-strength fibers in order to incorporate their specific properties intrastructurally into the final properties of the subsequently reinforced molded part.
• FIBRIT R supports (car door panels) are fixed one above the other at a distance of approx. 10 mm in a grid cage and attached to suitable fittings above the liquid level in a lid tank that contains 300 l of a commercially available MDI resin.
• the entire tank is evacuated at a temperature of 35 ° C to a pressure of 0.07 bar and tilted by 180 ° after 5 minutes.
• the FIBRIT R carriers get into the resin liquid, remain there for 30 s and return to the starting position by tilting by another 180 °.
• the parts are free of larger adhering liquid residues and are hardened at 95 ° C for a few hours.
• the weight increase of the parts is 24.5-26.0% by weight.
• the reinforced molded parts are boil-resistant and show a 3-fold increase in the elastic modulus compared to the initial value in the bending test. Outside weathering shows no negative results after 18 months except yellowing. The excess resin content cannot be measured in this way in terms of viscosity and NCO content.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Life Sciences & Earth Sciences (AREA)
• Wood Science & Technology (AREA)
• Forests & Forestry (AREA)
• Reinforced Plastic Materials (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=6176321

Family Applications (1)

Country Status (2)

Cited By (6)

Family Cites Families (4)

• 1982
  • 1982-10-22 DE DE19823239094 patent/DE3239094A1/de not_active Ceased
• 1983
  • 1983-10-14 EP EP83110249A patent/EP0107155A3/fr not_active Ceased

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