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
  • B27N1/00—Pretreatment of moulding material
• • 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
  • B27N1/00—Pretreatment of moulding material
  • B27N1/02—Mixing the material with binding agent

Definitions

• the invention relates to a process for the production of wood fiber boards, in which the raw material is subjected to fiberization, then glued in a blow line with an aqueous binder liquor and the glued fiber material obtained in this way, after drying, is scattered to the required residual moisture to mat webs and under pressure and temperature is pressed into plates.
• the invention relates to such a method for producing medium-density fiberboard (MDF) and hardboard (HDF), which contain a reduced amount of binder.
• MDF medium-density fiberboard
• HDF hardboard
• the mechanical properties of wood fiber boards are largely determined by the binder used to bind the fiber material. Under otherwise constant conditions, an increase in the mechanical strength of the plates is accompanied by an increase in the amount of binder used to bind the fiber material.
• the binder material represents an essential cost factor in the production of fiberboard
• a reduction in the amount of binder used leads, as already mentioned, to. a decrease in the strength of the panels made thereby.
• the raw material used is first subjected to machining and subsequent drying to a moisture content of preferably less than 2% before it is glued with an aqueous liquor of an aminoplast.
• the chips are glued in a glue mixer.
• thickeners such as cellulose derivatives, are added to the binder liquor in order to prevent the binder from penetrating into the chip material.
• the moisture of the glued chip material which is kept below 12%, is determined by the amount of water applied to the savings material with the binder liquor.
• gluing is carried out with a liquor with a solid resin content of 20 to 35% by mass, preferably 25 to 35% by mass, and a quantity of binder is used which is less than 10% by mass. preferably 7 to 9% by mass of solid resin, based on the total, atro calculated fiber material.
• the method according to the invention makes it possible to produce wood fiber boards with a solid resin content of less than 10% by mass, which have sufficient strengths in accordance with the applicable standards.
• Another advantage of this method is that the high dilution of the binder used exerts a cooling effect on the glued fiber, since part of the water contained in the binder mixture evaporates immediately, thereby removing heat from the entire fiber / binder system. This prevents premature pre-curing of the binder on the glued fiber, which pre-curing can also result in a decrease in panel strength.
• the present method according to the invention can be carried out without a significant change in the process technology.
• the gluing of the fiber material takes place shortly after it emerges from the defibration machine (refiner) in the blow line in a conventional manner.
• Suitable hardening substances such as, for example, ammonium chloride, aminonium phosphate, phosphoric acid, formic acid, are added to the glue liquor to harden the binder used during the hot pressing process, in the amounts known in the art, which depend on the particular plant conditions.
• Glue booster based on a lignin sulfonate proven.
• additional formaldehyde scavengers such as urea, can also be added to the binder liquor.
• paraffin emulsion or melted paraffin to make the fiberboard hydrophobic is advisable / travel before entering the refiner.
• the fiber material which has been provided with binder in the manner described above, is then dried in a manner known per se to a residual moisture of at most 1296, advantageously at most 10%, before it is pressed into sheets after forming mat webs in conventional heating presses .
• the pressing to plates can be done in conventional stationary presses at temperatures of around 160 to 190 ° C and pressures up to 35 bar or in contipresses at heating plate temperatures up to 235 ° C and the usual pressure programs.
• the pressing times correspond to the pressing times which have also been used to date.
• a preferred embodiment of the process according to the present invention is that the aminoplastic binder used is first diluted with water to a solid resin concentration of approximately 30 to 40% by mass and the necessary additives such as hardening substances, glue booster, formaldehyde scavenger, in a suitable aqueous solution
• the diluted binder solution is only added via a mixing section immediately before entering the blow line.
• MDF medium density fiberboard
• a fiber material was used, which had been produced in a manner known per se from wood chips in a fiberising machine (refiner).
• a binder-containing mixture was metered into the blow line, through which the fiber material is discharged from the refiner, shortly after it emerged from the refiner.
• This binder-containing mixture was composed as follows:
• an aminoplastic El glue for the fiberboard products (HIACOLL MDF 15) was diluted with water to a concentration of 33% by mass of solid resin.
• a solution was placed in a second mixing container of 30 mass% urea, 10 mass% ammonium chloride and 2 mass% phosphoric acid. With the help of dosing pumps, the two solutions were combined in a ratio using a static mixer in such a way that the final glue liquor contained a concentration of solid resin of 28.3% by mass.
• This glue liquor was added to the fiber material in such an amount that a glue factor of 8.2% by mass of solid resin, based on absolutely dry (atro) fiber, was obtained.
• the glued fiber mixture was then dried in a known manner to a residual moisture content of 10% by mass, shaped into a fiber mat and pressed in a heating press under the action of pressure and temperature to form an MDF plate.
• the board produced in this way very well met the requirements of the industry standard for MDF boards (standard type MDF, formaldehyde content class A).
• a fiber material according to Example 1 was glued in a manner known per se with the following binder-containing mixture:
• Example 3 is a comparative example.
• a glue liquor of the following composition was used for the gluing of fiber material, which was carried out as described in Examples 1 and 2:
• this glue liquor corresponds to the state of the art. It has a solid resin concentration of 53.2% by mass. In order to achieve the mechanical values required by the industry standard for MDF boards of an MDF board manufactured using this liquor, 235 kg of glue liquor had to be used per 1,000 kg of dry fiber material, which corresponds to a gluing factor of 12.5% by mass, based on dry fiber material .

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)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

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ID=3486297

Family Applications (1)

Country Status (14)

Cited By (2)

Families Citing this family (1)

Citations (4)

Family Cites Families (3)

• 1991
  • 1991-02-08 AT AT0027891A patent/AT403023B/de not_active IP Right Cessation
• 1992
  • 1992-02-02 CN CN92100691A patent/CN1063837A/zh active Pending
  • 1992-02-03 NZ NZ241508A patent/NZ241508A/xx unknown
  • 1992-02-05 TR TR00130/92A patent/TR26826A/xx unknown
  • 1992-02-06 ZA ZA92874A patent/ZA92874B/xx unknown
  • 1992-02-07 EP EP92903957A patent/EP0570435B1/de not_active Revoked
  • 1992-02-07 WO PCT/AT1992/000016 patent/WO1992013688A1/de not_active Application Discontinuation
  • 1992-02-07 SI SI9210125A patent/SI9210125A/sl unknown
  • 1992-02-07 DE DE59202092T patent/DE59202092D1/de not_active Revoked
  • 1992-02-07 IE IE920406A patent/IE67381B1/en not_active IP Right Cessation
  • 1992-02-07 ES ES92903957T patent/ES2074874T3/es not_active Expired - Lifetime
  • 1992-02-07 DK DK92903957.6T patent/DK0570435T3/da active
  • 1992-02-07 PT PT100106A patent/PT100106A/pt not_active Application Discontinuation
  • 1992-02-07 AU AU12256/92A patent/AU1225692A/en not_active Abandoned

Patent Citations (4)

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