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
  • B27N3/04—Manufacture of substantially flat articles, e.g. boards, from particles or fibres from fibres
• • 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
• • 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
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/249921—Web or sheet containing structurally defined element or component
  • Y10T428/249924—Noninterengaged fiber-containing paper-free web or sheet which is not of specified porosity
  • Y10T428/249933—Fiber embedded in or on the surface of a natural or synthetic rubber matrix

Definitions

• the invention relates to a method for preparing natural fibre-based composite materials containing natural binders and powdery proteins .
• products are made in the form of artefacts such as panels and boards, composed of wood and/or non-wood natural fibre materials and a protein as the sole binder component (added) .
• Typical resins used during the mixing process are urea formaldehyde (UF) resins, phenol formaldehyde (PF) resins and melamine urea formaldehyde ( UF) resins.
• UF formaldehyde
• PF phenol formaldehyde
• UF melamine urea formaldehyde
• aqueous resin is sprayed on the dry wood or vegetable fibres (2-4% moisture) and the whole is blended.
• the fibres dosed with resin can then be submitted to a further drying step.
• the resin-dosed fibre is pneumatically or mechanically conveyed to the intermediate storage bins. From here, the fibre is transported to the mat forming line and to the pre-press.
• the thus formed mats are then entering the press and stacked. These mats are then submitted to hot pressing to consolidate the mat to a desirable panel density and thickness, to cure the resins and to heat stabilise the panel so that it will remain at the target thickness and density under normal service conditions. Also continuous presses can be used. The thus obtained panels are then finished by shaving-off the edges by sanding the surfaces .
• a disadvantage of this process is that the fibre material must be dried to a sufficient level to allow the blending with the liquid resin; otherwise homogeneous blending is not possible while lump formation occurs at too high moisture content .
• the resin adhesives can be partially or fully replaced by renewable resources .
• the resultant fibreboard has the disadvantage that it has no moisture resistance.
• animal proteins in powder form is further disclosed in Sovjet patent application SU 1 813 640.
• lime milk (1,6-3,2%) and water (35- 45%) are added to a fibre material at about 4% moisture content.
• 8-16% albumin or casein powder glue is added, and the whole is mixed until the glue is uniformly distributed into the fibre material .
• the composition is then heated between 140-170°C at a pressure of 1,4-2,5 Mpa, this during 0,6-1,0 min/mm.
• wheat gluten as an adhesive has been disclosed in Starch (1968, vol20, n°12 p.395-399).
• the gluten that is used is reduced with sodium sulphite or thioglycolic acid.
• the disadvantage related to these products is that the wheat gluten adhesive is obtained through a chemical reaction in an aqueous medium.
• the wheat gluten glue used is a dispersion at 55-60% d.s., obtained by dispersing gluten into a solution of urea, citric acid and sodium bisulpite.
• the gluten glue which is first mixed with a cross-linker
• thermoplastic processing in which a vegetable material containing fibre, or a mixture of such vegetable materials, are subjected to at least one thermoplastic processing step.
• the thermoplastic processing may be carried out in the presence of a bonding agent, for example a chemical bonding agent such as urea-formaldehyde, or a protein
• the vegetable material (s) Prior to the thermoplastic processing step(s), the vegetable material (s) are subjected to at least one preliminary treatment .
• the product of the thermoplastic processing step(s) may be subjected to an after-treatment.
• the vegetable material (s) may be mixed with additives prior to and/or during the thermoplastic processing step(s) .
• the composites may be formed in a variety of configurations, including board, sheets and films, and may find use as constructional items.
• the disadvantage is that when proteins are used as the sole binder, relative to the total of the fibrous vegetable material and protein, the amount of water may be in the range of 25 to 50% by weight. As a result thereof, the compression-moulded articles must be submitted to an additional time and energy consuming drying step.
• the purpose of the invention is to resolve the abovementioned disadvantages. This purpose is achieved by providing a method for preparing natural fibre-based composite materials containing natural binders and powdery proteins, comprising the following steps:
• the ratio of natural fibres and protein powder adhesive varies between 19:1 up to 1:1.
• the heat pressure treatment is performed within a temperature range of 100 - 250 °C.
• the proteins added to the fibres have a moisture content varying between 4 and 14 % w/w.
• the proteins added to the natural fibres have a moisture content between 8 and 12 % w/w.
• the wood or plant fibres have a moisture content between 1 and 20 % w/w.
• the wood or plant fibres have a moisture content between 2 and 15 % w/w.
• the natural fibre-based composite materials include one of the products selected from packaging materials, decorative items, backing materials or structural materials.
• said natural fibres can be obtained from whole plants or various parts thereof.
• said natural fibres can be of animal origin.
• said powdery protein adhesive can be of animal origin. In another preferred method according to the invention, said powdery protein adhesive can be of vegetable origin.
• the final moisture content of the composition is adjusted to 12 - 20% w/w.
• the final moisture content of the composition is adjusted to 14 - 18 % w/w.
• the ratio of natural fibres and protein powder adhesive vary between 9:1 and 2:1.
• the ratio of natural fibres and protein powder adhesive vary between 9 : 1 and 2,5:1.
• the heat pressure treatment is performed within a temperature range of 175 - 225 °C.
• the heat pressure treatment is performed by means of compression moulding or by hot pressing in open presses.
• a pressure is exercised that is sufficient to obtain a natural fibre-based composite material with a density varying between 0,5 kg/dm 3 and 1,5 kg/dm 3 .
• natural fibre-based composite materials concerns reconstituted products containing natural fibres originating from wood and/or annual plants, and an adhesive.
• Such composite materials include e.g. packaging materials, decorative items, backing materials, structural materials. More particularly, it refers to construction or building materials such as e.g. particleboard, medium density and high-density fibreboard, oriented strand board or chipboard.
• Other compositions comprise e.g. packaging materials (bottles, containers) , decorative items (door panels) , backing materials (carpet tiles, roofing materials) , or structural materials (e.g. car bumpers) .
• natural fibre materials can be obtained from whole plants or from various parts thereof. Textile fibres such as cotton, flax hemp or ramie can be used, but also meal products from the cereals or oilseed processing industry. Typical examples thereof are wheat bran, corn bran, wheat straw, barley husks, rapemeal, sunflower meal, soybean meal, etc.
• the natural fibre materials can also be of animal origin such as wool, silk or keratin-waste, etc.
• the powdery protein adhesive can be of animal or vegetable origin.
• Animal protein sources are e.g. milk proteins, caseinates, whey concentrates and isolates, gelatine, fish proteins, egg albumin, plasma proteins, animal flours, etc.
• the vegetable proteins can be selected among e.g. cereal proteins, tuberous proteins, proteins from leguminous origin, or oilseed proteins.
• Typical cereal proteins that can be used are wheat gluten, or maize gluten and derivatives thereof.
• soy protein concentrates and isolates, rapeseed protein concentrates or sunflower protein concentrates, or derivatives thereof can be used, also. This list must not be considered as limiting, but merely as an illustration of the protein sources that can be used.
• the proteins added to the natural fibres have a moisture content varying between 4 and 14% w/w, preferably varying between 8 and 12 % w/w.
• the wood or plant fibres may have a moisture content between 1 and 20 % w/w, 2 to 15% w/w being preferred.
• the moisture content of the fibres can be higher because no additional moisture is added via the binding agent. This can offer an additional advantage with regard to drying cost reduction of the wood or plant fibres.
• the natural fibres together with the powdery adhesive are mixed, and the final moisture content of the fibre/protein composition, before the heat pressure treatment, may vary between 6 and 24% w/w.
• Preferred ranges of moisture content are between 12 and 20% w/w, more preferably between 14 and 18% w/w. It is believed that his moisture content activates an initial sticking process, in which there occurs an interaction between the proteins and the fibres. In this way, there is already a stabilisation before the heat pressure treatment.
• the moisture content of the protein/fibre composition is too low, the phases can separate.
• the moisture content of the fibre/protein composition is too high, more heat is needed to remove the water, and the final product has a less mechanical strength.
• With a moisture content between 6 and 24% w/w the fibre/protein composition is already sufficiently homogeneous, which avoids an extra kneading step.
• the ratio of natural fibre material and protein powder adhesive may vary between 19:1 up to 1:1, preferably between 9 : 1 and 2 : 1 and more preferably between 9 : 1 and 2,5:1.
• Heat pressure treatment of the fibre/adhesive composition is performed within a temperature range of 100-250 °C, preferably between 175°C and 225°C. Pressure exercised during hot pressing must be sufficient to obtain densities varying between 0,5 kg/dm 3 and 1,5 kg/dm 3 .
• the heat pressure treatment of the compositions may be performed by means of compression moulding or by hot pressing of the fibre/protein composition.
• the processing parameters, in particular temperature, pressure, and processing time will depend in any given case upon the nature of the starting materials and desired properties of the end products. It is observed that temperature evolution in the core of the product during hot pressing or compression moulding is quite fast, as illustrated by figure 1 (see example 4) .
• the panel products obtained by means of the processes according to the invention do show excellent mechanical properties and sufficiently low water sensitivity.
• the prepared composites according to the invention are composed of biodegradable compounds. This can be of importance where materials are difficult to recycle.
• the hemp fibres are mixed with wheat gluten in a tumbling mixer (Heidolph Rheax 2, Germany) for 10 minutes.
• the volume of the mixing bowls is 100 ml, the total mass is 10g, the fibre weight fraction is 0.6, 0.7, 0.8, 0.9 w/w.
• Water is sprayed in the mixing bowl in order to raise the final water content to 18 %, the water content of the mixture without water addition being 9%.
• the fibre/gluten mix is poured into a cylindrical mould (diameter 35 mm) and pressed for 10 minutes at 100, 125, 150, 175, and 200°C under 10T load.
• the thickness swelling is then determined as the percentage increase of the sample thickness as measured at the centre of the disks with a digital calliper square.
• the material density is determined after measuring the sample thickness and diameter with a digital calliper square to the nearest 0,01mm and weighting the sample on a precision balance.
• the moisture content of raw materials and samples is determined by weight difference after 24h drying at 104°C.
• Wood particles (8.5 % MC, Unilin NV, Schaapdreef 36, B- 8710 Wielsbeke)
• Methods - Mixing The fibres are mixed with wheat gluten in a 5 1 rectangular mixing bowl by hand for 10 min, simulating the movements of a tumbling mixer.
• Pressing A rectangular fibre mat of dimensions 17x26 cm and about 4cm height is formed by hand using a wooden frame. A k type thermocouple is placed in the centre of the fibre mat. After removal of the wooden frame, the mat is placed into the heated press (regulated at 175°C) and the temperature recording is started. The mat is compressed to 11 mm final thickness in a hand pump hydraulic press. The time needed for press closure to 11 mm is 60s, the load is maintained for 120s, then the load is relaxed gradually to zero during 1 min. The total pressing time is 4 min. 4 flexion specimens (30*170 mm) and 2 specimens (50*50 mm) for thickness swelling and determination of density are cut of each board.
• the mechanical properties are investigated in bending mode with a ZWICK 500N universal testing machine.
• the distance between flexion points is 100 mm
• cross-head speed is 2mm/min.
• the samples are tested immediately after their fabrication.
• Thickness swelling is investigated according to norm EN 319.
• the test specimens are immersed in distilled water (20°C) , thickness is determined in the centre of the test specimen after 2 and 24h of immersion.
• FIGURE 1 Core temperature evolution during pressing of gluten and wood particles. 175° "C regulation temperature, 300g wood (9%MC) , 60g gluten (7%MC)
• Figure 1 shows the core temperature evolution during the fabrication of a gluten wood particleboard. It is observed that temperature rises very rapid as soon as the press is closed and the nominal thickness is reached. Core temperature reaches 150°C in 30 sec after press closure (90s total press time) .
• MOE G a 0,976 1,029 1,077 0,636 sdev 0,094 0,188 0,201 0,184
• MOE is modulus of elasticity
• MOR is modulus at break
• TS is thickness swelling after immersion in 20°C water.
• EN 312-2 general purose particleboard
• mechanical properties of different protein /fibre compositions are determined.
• the same method as in example 1 is used, except that the panels were formed in a rectangular mould of 120mm x 10mm. Moulding temperature is 175°C and moisture content is 9%. The fibre fraction is 0,8. Thickness obtained is between 5 and 6 mm.
• Mechanical properties are investigated according to norm EN ISO 14125 in bending mode with TAXT2 texture analyser (Stable Microsystems, UK) . The distance between flexion points is 100 mm. The samples are analysed directly after fabrication. The results are displayed in table 5.
• This example illustrates the effect of the pressing temperature on the mechanical properties of the fibre boards prepared with wheat gluten as the sole binder.
• the boards in this example are prepared by mixing 300g wood fibres (2% moisture) with 33, 3g wheat gluten (7% moisture) in a T-bar rotating mixer for 3 minutes. Then 25g water, mixed with 5 , 5g parrafin emulsion was added and mixed for an additional 7 minutes.
• the pressing procedure as described in example 4 is slightly modified, whereby the pressing temperature was increased to values of 200°C and 225°C and pressing time was lOs/mm. Density of the boards thus prepared varied between 0,732 and 0,735.

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• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Forests & Forestry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Health & Medical Sciences (AREA)
• Materials Engineering (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Dry Formation Of Fiberboard And The Like (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Compounds Of Unknown Constitution (AREA)

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• 2001
  • 2001-01-23 GB GB0101630A patent/GB0101630D0/en not_active Ceased
• 2002
  • 2002-01-21 CN CNB028040341A patent/CN1243060C/zh not_active Expired - Fee Related
  • 2002-01-21 PT PT02716681T patent/PT1363974E/pt unknown
  • 2002-01-21 WO PCT/EP2002/000665 patent/WO2002059212A1/en not_active Ceased
  • 2002-01-21 DK DK02716681T patent/DK1363974T3/da active
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