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
  • B27N3/06—Making particle boards or fibreboards, with preformed covering layers, the particles or fibres being compressed with the layers to a board in one single pressing operation
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L97/00—Compositions of lignin-containing materials
  • C08L97/02—Lignocellulosic material, e.g. wood, straw or bagasse
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T156/00—Adhesive bonding and miscellaneous chemical manufacture
  • Y10T156/10—Methods of surface bonding and/or assembly therefor
  • Y10T156/1089—Methods of surface bonding and/or assembly therefor of discrete laminae to single face of additional lamina
  • Y10T156/1092—All laminae planar and face to face
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T156/00—Adhesive bonding and miscellaneous chemical manufacture
  • Y10T156/10—Methods of surface bonding and/or assembly therefor
  • Y10T156/1089—Methods of surface bonding and/or assembly therefor of discrete laminae to single face of additional lamina
  • Y10T156/1092—All laminae planar and face to face
  • Y10T156/1093—All laminae planar and face to face with covering of discrete laminae with additional lamina

Definitions

• the present invention relates to a process for the manufacture of boards, in which sawdust is mixed with a binding agent and the mixture is subjected to a pressure at an elevated temperature.
• a process for the manufacture of boards of this type has already been proposed, in which sawdust having a particle size ranging between 2 mm. and 9 mm. is used and mixed with a quantity of thermosetting binding agent, ranging between 7% and 10% of the weight of dry resin, this mixture then being subjected to a pressure ranging between 25 kg./cm. and 35 kg./cm. at a temperature ranging between 130 C. and 140 C.
• the boards obtained according to this process have characteristics of bending, water-absorption and swelling, which makes them unsuitable for use as covering panels of very low thickness, i.e. of 0.5 mm. to 5 mm.
• the present invention has for its object a process for the manufacture of boards of very low thickness from a mixture of sawdust and a binding agent, which has mechanical properties similar to those hitherto obtained by ply boards formed from [live to six superimposed sheets of paper, which are impregnated with a phenolic binding agent and compressed under pressure at elevated temperature.
• the mixture is effected with sawdust having a particle size below 1 mm. and with a quantity of binding agent ranging between 5% and of the weight of the dry dust; said layer is formed by spreading the mixture in a layer of such a thickness that a final layer of a thickness ranging between 0.5 mm. and 5 mm. is obtained, and by simultaneously applying a pressure ranging between 80 kg/cm? and 150 kg./cm. and a temperature ranging between 130 C. and 180 C.
• sawdust which has a moisture content of 5% to 15
• thermosetting binding agent a thermosetting binding agent
• the binding agent is advantageously a phenolic resin.
• the binding agent is an abietic resin.
• the binding agent contains lignin.
• the binding agent advantageously contains several resins chosen from among the resins of the phenolic, fossil, natural type and lignin type.
• the mixture contains an agent increasing the internal resistance to heat of the boards formed.
• This agent advantageously consists of five parts by weight of cement or plaster calculated on the mixture.
• a layer of the mixture of sawdust and binding agent is applied to a supporting sheet consisting of a cellulosic material, for example paper impregnated with phenolic resin.
• the support consists of a synthetic plastics material such as a polyvinyl or polyolefin.
• the mixture of sawdust and binding agent is subjected to a cold precompression at a pressure ranging between 10 kg./cm. and 40 kg./cm.
• This precompression permits the production of a cake facilitating the subsequent application of a cover paper prior to the hot compression.
• This cover sheet consists of a cellulosic material impregnated with a synthetic plastic resin, such as polyester, acrylic, epoxy, or of a film of plastics material produced with the above-stated materials. This cover forms advantageously a support for ornamental elements.
• EXAMPLE 1 Continuous manufacture of a finished board of 1.5 mm. thickness A mixture is prepared comprising parts by weight of sawdust of a particle size below 1 mm. and having a moisture content of about 8.5% and 10 dry parts of a phenolic resin in the dry state. The composition, whose pH is 7.5 is homogenised. The mixture is spread onto a phenolised sheet of kraft paper conveyed on a continuously rotating conveyor belt. This sheet is intended to form the back of the adhesive surface of the board. The layer of mixture is spread in a uniform manner to a thickness of about 8.5 mm. by means of a rotary brush which rotates in the direction opposite to that of the forward motion of the board in formation.
• a cover sheet such as an ornamental paper impregnated with melamine resin is applied to the layer thus formed, and a glossy or matt according to the final aspect desired-metal sheet is applied to the latter.
• the whole is inserted between two platescooled to approximately 40 C.of a press, The press is slowly closed to allow the air to be evacuated and a pressure of kg./cm. is applied for 5 minutes to the layer of material, the plates of the press being heated to about C.
• the plates are cooled by circulating cold water and when the internal temperature has dropped to 50 C. the press is opened.
• the board obtained has a thickness of 1.5' mm. and a density of 1.35 g./cm.
• the resistance to bending by compression of the decorated surface is 800 kg./cm. to 900 kg./cm.
• the increase of volume after standing in water at 100 C. for 2 hours is 4.5% whilst the increase of weight is 5%.
• EXAMPLE 2 Manufacture of a finished panel of 3 mm. thickness decorated on both faces A mixture is prepared comprising:
• the mixture which has a pH of about 8.5 is homogenised.
• a 19 mm. layer of the mixture is spread onto a supporting paper impregnated with phenolic resin and conveyed on a conveyor belt. The whole is subjected to a precompression of 30 -kg./cm. at ambient temperature.
• the cake provided with its support is then placed on a metal sheet covered by a decorated, melamine-impregnated paper and to the upper face of the cake are successively applied: a supporting paper impregnated with a phenolic resin, a decorated paper impregnated with a melamine resin and a metal sheet.
• the upper and lower metal sheets are polished, matt or grainted according to the final aspect desired.
• the whole is introduced between two plates of a press cooled to 40 C. and then compressed for -8 minutes at 100 kg/cm. at a temperature of 150 C.
• the plates are cooled to less than 50 C. and the pressure is relaxed.
• a very rigid board of a thickness of 3 mm., having a density of 1.40 g./cm. and a very low water absorbing power is obtained.
• the resistance to bending by compression is 700 to 800 kg./cm.
• the increase of volume after standing in water for two hours at 100 C. is 3.5% and the weight increase 4%.
• EXAMPLE 3 The present invention likewise allows one to obtain boards of a greater thickness of about 20 mm. as will be described in the present example.
• This board has a central layer having sawdust of a particle size above 1 mm., for example below 2 mm., and on either side thereof an outer layer comprising sawdust of a particle size below 1 mm., for example below 0.5 mm.
• two mixtures of sawdust of different particle sizes are prepared, for example one of less than 0.5 mm. and the other less than 2 mm.
• These mixtures comprise:
• the whole is subjected to cold precompression at a pressure of 40 kg./cm. and the cake thus obtained is placed onto a metal sheet.
• An identical rigid polyvinyl chloride and a metal sheet are applied to the surface.
• the two metal sheets are glossy, matt or grained, according to the final aspect which one desires to obtain.
• the plates are cooled and the pressure is relaxed.
• the board obtained has a thickness of 20 mm.
• the bending strength is 650 kg./cm.
• the increase of volume after standing for 2 hours at 100 C. is 1.7% and the weight increase 15%.
• the binding agent is of thermoplastic nature, such as artificial resin e.g. polyvinyl chloride or natural products, such as abietic resin, designated Vinsol or also an asphalt or a fossil resin such as gilsonite, or else lignin, for example extracted from the residual washing solutions of paper pulp factories.
• artificial resin e.g. polyvinyl chloride or natural products, such as abietic resin, designated Vinsol or also an asphalt or a fossil resin such as gilsonite, or else lignin, for example extracted from the residual washing solutions of paper pulp factories.
• the binding agent is of thermosetting nature, such as a phenolic formaldehyde resin or one based on furfural.
• said organic binding agent is a phenolic resin, an abietic resin or lignin.
• said supporting sheet comprises a cellulosic material or a synthetic resin.
• cover sheet is a cellulosic material impregnated with a synthetic resin selected from the group consisting of polyesters, acrylics and epoxies.
• cover sheet is a film of a synthetic resin selected from a group consisting of polyesters, acrylics and epoxies.

Applications Claiming Priority (1)

Publications (1)

Family

ID=19725528

Family Applications (1)

Country Status (5)

Cited By (44)

Families Citing this family (11)

• 1968
  • 1968-03-11 LU LU55657D patent/LU55657A1/xx unknown
• 1969
  • 1969-03-04 US US804302A patent/US3673020A/en not_active Expired - Lifetime
  • 1969-03-06 FR FR6906199A patent/FR2003620A1/fr not_active Withdrawn
  • 1969-03-11 DE DE19691912300 patent/DE1912300A1/de active Pending
  • 1969-03-11 GB GB1228566D patent/GB1228566A/en not_active Expired

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