• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    Process of manufacture of boards from macrophyte plants with aerenchyma tissue and boards obtained from said process. The present invention relates to a process for the manufacture of agglomerated particle boards without added adhesives comprising: separating the cortex from the marrow of a macrophyte plant with aerenchyma tissue; crushing the bark and marrow obtaining particles that are separately subjected to a drying process; dispose of the dried particles in a blanket of marrow particles and a blanket of bark particles to which free water is added; press the blankets at a temperature between 130 and 160ºC, for a time of 10 to 20 minutes and a pressure of 4 MPa, giving rise to the agglomerated boards of marrow particles and agglomerated boards of bark particles, which let cool to room temperature. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2705437A1
    申请号:ES201831156
    申请日:2018-11-28
    公开日:2019-03-25
    发明作者:Cordero Juan Fernando Hidalgo；Navarro Justo Garcia
    申请人:Universidad Politecnica de Madrid；
    IPC主号:
    专利说明:

    [0001]
    [0002]
    [0003] MACRÓFITAS WITH AERÉNQUIMA TISSUE AND BOARDS OBTAINED TO START
    [0004]
    [0005] TECHNICAL SECTOR
    [0006] The present invention fits within the construction sector. In particular, it refers to a new process for the manufacture of boards from macrophyte plants, as well as to the boards obtained from said process.
    [0007]
    [0008] BACKGROUND OF THE INVENTION
    [0009] Wood forest resources are widely used in the construction industry for their good environmental, physical and mechanical properties. However, the growing demand for this type of materials and the need to improve the management of this resource have led the industry to look for alternative sources of lignocellulosic materials such as non-wood forest resources, agricultural residues or industrial by-products. In spite of the advances in this field of study, in the conventional practice for the production of building materials from lignocellulosic particles or fibers, a large amount of petroleum-based adhesives is still being used, which may pose risks to human health, as it is the case of formaldehyde-based resins. However, the elements present in lignocellulosic materials are able to react, under certain conditions of pressure and temperature, to generate bonds that promote adhesion without the need for added elements. One of the first references to this property of wood is the patent US1663503, which describes the production process of wood fiber boards obtained by steam explosion. With these fibers previously activated by the steam, wet blankets are formed which are pressed between rollers to expel the residual water and form the thermal insulating boards without added adhesives.
    [0010]
    [0011] Likewise, the patent US2557071 describes a process of making piywood boards (plywood) using wooden sheets. The process involves activating the lignin in the wood by means of a previous autoclave treatment with steam at high temperatures between 200 and 285 ° C and 200 psi of pressure. These activated sheets are then dried and then placed one on top of the other and subjected to a pressure of about 750 psi and 220 ° C temperature. Through this process, the components of the laminated boards are adhered by the lignin contained in the wood without the need for added adhesives.
    [0012]
    [0013] Inventions based on the use of non-wood fibers have also been described in the state of the art. Thus, for example, patent application JP2003200407 describes a process for obtaining a board without added binders using herbaceous plants and agricultural residues such as kenaf, bamboo, bagasse, rice straw, wheat straw or flax. The process consists of forming blankets with these fibers and subjecting them to heat and pressure, while injecting steam at 160 ° C with a pressure of between 8 and 10 atm to activate the sugars contained in the hemicelluloses of the cell walls of the fibers vegetables. This process is carried out in a hot plate press with steam injection. The hemicelluloses, once hydrolyzed, are more susceptible to react and form bonds between them, so that a rigid board is formed without the need for added adhesives.
    [0014]
    [0015] Also, patent application JP2007021972 describes the manufacturing process of a board made with whole stems of herbaceous species such as kenaf, jute, hemp, rice straw, bagasse, wheat, corn, and sunflower. The stems are cut so that long pieces are obtained which can be oriented in parallel to form a blanket, or perpendicularly in several layers. It is mentioned that the stems of kenaf, jute, hemp and flax can be used to exclude the fibers of the bark and that, by using the sections of stems without crushing, the resistance of the boards is improved when the whole cells remain.
    [0016]
    [0017] Additionally, the international application WO2010130096 describes a process for obtaining and using fine powder with particles of a maximum of 200 microns in diameter, obtained from lignocellulosic materials such as rice husk, sawdust, tree bark, sugarcane bagasse, husks, corn husk. , or their mixtures. This powder can be mixed with a maximum of 15% of a conventional adhesive and by treating the mixture with pressure between 1 and 20 MPa and heat between 160 and 210 ° C an adhesive capable of sticking wooden sheets to form a board is achieved.
    [0018] Patents have also been described aimed at optimizing the use of energy by applying relatively low temperature and pressure conditions for the manufacture of boards without added binders. For example, patent ES2390853 describes a process for obtaining particle boards by applying several heat cycles between 90 and 130 ° C and pressure between 25 and 35 kg / cm2, characterized in that the temperatures and pressures employed are significantly lower than conventionally used for this type of boards.
    [0019]
    [0020] The patent application US20130199743 describes a process for manufacturing a medium density board using a mixture of cellulose fibers with wood particles in a 50:50 ratio in an aqueous medium. The invention describes the advantages of using the mixture of fibers and particles in that it favors the drainage and movement of water within the matrix and the adhesion of the fibers by the natural compounds of the particles when subjected to pressure and heat. The wet blanket is subjected to vacuum for water extraction and subsequently to several pressure cycles between 10 and 600 psi and temperatures between 117 and 204 ° C.
    [0021]
    [0022] The international application W02017108130 describes a process for obtaining agglomerated boards of materials containing lignin, especially coconut fiber, by applying temperatures between 140 and 220 ° C and pressure between 120 and 170 bar. In this method the material to be used must not have been cut more than 6 months ago and must be conditioned until it has a moisture content between 12 and 25%. A first cold compression is made up to 1/5 of the original thickness and then pressure and heat are applied. It is described that the bonding is due to the fact that under conditions of pressure and heat the lignin becomes viscous and is able to flow and create bonds between the particles that are sufficiently close together due to the pressure.
    [0023]
    [0024] Patent documents have also been located regarding the use of macrophyte species for the manufacture of different products. This is the case of patent JP4003075, which describes a method for obtaining papyrus sheets by applying pretreatments to the plant that promote self-adhesion even under low temperature conditions. The method takes advantage of the natural capacity of adherence of the strips obtained from the medulla of the papyrus, improving this capacity through the use of solutions and acid salts.
    [0025] Most of the current supply of wood-based boards are produced using adhesives harmful to health such as those based on formaldehyde and compounds with volatile emissions. In addition, the growing demand for wood-based products puts increasing pressure on arable land and forest forests.
    [0026]
    [0027] Thus, the present invention aims to solve the above problems by using non-wood plant species such as macrophytic plants. This type of plants have a series of advantages such as their rapid growth, their natural annual cycle (they die naturally every year) and that the environment in which they grow does not compete with agricultural or forestry lands.
    [0028]
    [0029] Some macrophyte species are beneficial for water purification and have been used in a traditional way by several communities for the development of handicrafts, boats, utensils and even housing such as the totora (Schoenoplectus californicus) and other similar species. Despite the wide diversity of traditional uses that have been given to these plants and the benefits they present from the environmental point of view, the fields of application of these species in the current context are still limited.
    [0030]
    [0031] The present invention aims to expand the fields of application of this type of plants, according to the requirements of the current industry. The main objective is to take advantage of this non-wood resource for the production of self-agglomerated boards applicable in construction, obtaining better results with a lower energy consumption and without added adhesives.
    [0032]
    [0033] DESCRIPTION OF THE INVENTION
    [0034] A first object of the invention relates to a process for the manufacture of agglomerated particle boards without adhesives added from at least one macrophyte plant whose stems are constituted by a central tissue or marrow of spongy consistency (aerenchyma) surrounded by a tissue external or cortex, where said process is characterized by comprising:
    [0035] (a) separate the bark from the marrow of the plant, because the behavior of these two tissues under pressure and temperature is different. This separation it can be carried out by manual separation or by the use of a cutting instrument such as a blade or the like. Also, the separation can be done with the stems of the plant freshly cut or once dried;
    [0036] (b) once the cortex is separated from the marrow, both are crushed separately. In particular, the cells of the central tissue (medulla) have a structure of thin cell walls and little compact, so they can be crushed with less intensity to obtain a particle size equal to or less than 2 mm. This is because it is a relatively soft material compared to conventional wood species and allows the use of a wider range of particle sizes due to the shape of the cells that comprise it. In this way, an energy saving in the grinding phase of up to 15% can be achieved. At the same time, the marrow particles can be agglomerated under relatively low pressures, which can vary from 1 MPa to 3 MPa. The state of compaction required to form the bonds between the particles can thus be achieved by the reaction of hemicellulose and lignin at pressures below the conventional ones, which are usually of the order of 4 MPa. In turn, the particles of the crust can be crushed to obtain a particle size equal to or less than 0.5 mm;
    [0037] (c) once crushed, the marrow and bark particles are subjected, separately, to a drying process at temperatures not higher than 100 ° C. The fact that the drying process is carried out separately makes it possible to optimize the use of energy by taking advantage of the difference in drying times required by the marrow and bark tissue, being approximately half in the case of marrow tissue.
    [0038] Said drying process allows to reduce the moisture content until reaching a moisture content of between 1 and 2% in the case of the marrow particles and between 1 and 3% in the case of the bark particles, determined by difference of the content of dry matter according to the norm UNE-EN ISO 638: 2008 - Determination of the content of dry matter: Method of drying in stove. By reducing the moisture content it is possible to avoid that the internal humidity is released in the form of steam during the pressing process and that microcracks are formed in the final product;
    [0039] (d) then, the dried particles are arranged forming a blanket of marrow particles to which it is added (preferably by spraying) between 1 and 2% free water and a blanket of bark particles to which it is added. you it adds (preferably by spraying) between 1 and 3% of free water, which is more reactive than the internal humidity, to promote the reaction of the hemicellulose and lignin of the particles. In the case of bark particles, the formation of microcracks is less severe because the particles compact less easily and moisture can escape easily;
    [0040] (e) once the blankets are formed, they are subjected to a pressing process at a temperature between 130 and 160 ° C (preferably 150 ° C) for a time of 10 to 20 minutes (preferably 15 minutes) and a pressure of 1 to 4 MPa (preferably 3 MPa);
    [0041] (f) once this time has elapsed, the pressure is removed and the agglomerate boards of particles obtained from the process are allowed to cool, preferably in a horizontal position or in such a way as to avoid possible deformations, until reaching an equal or close temperature at room temperature (generally, about 25 ° C).
    [0042]
    [0043] Thus, with the claimed process boards are obtained without the need for adhesives or binders added, using relatively low temperatures and pressures.
    [0044]
    [0045] As a result of the separation of the bark and the marrow of the plant, the process is optimized, reducing energy consumption by around 25% and avoiding the need to add adhesives. In particular, the central tissue or marrow of the macrophyte plants used in the process is more hygroscopic than the bark, so the equilibrium moisture is different in both cases. In this way, if the complete macrophytic plants were used (without carrying out the separation of the bark and the marrow) the particles of the marrow, which hydrolyze more easily, would form microfractures due to the accumulation of water that is released in the form of steam in the process of shaping the board, reducing the properties of mechanical strength of the final product. The separation of both tissues, therefore, manages to solve this problem, which is an important advantage of the claimed process compared to other alternatives of the state of the art.
    [0046]
    [0047] As indicated, the macrophyte plant used in the process object of the invention will have an internal structure composed of an aerenchyma tissue, namely, a very low density spongy tissue, between 0.05 and 0.5 g / cm3. Of Even more preferably, said macrophytic plant will be the totora (Schoenoplectus californicus).
    [0048]
    [0049] Another object of the invention is the board without adhesives obtained from said process, which is characterized by having distinctive characteristics compared to other boards known from the state of the art.
    [0050]
    [0051] The boards obtained from marrow particles have an average density between 0.75 and 0.89 g / cm3 (preferably 0.83 g / cm3), measured according to the UNE-EN 323: 1993 standard - "Boards derived from wood - Determination of the density"; a static bending strength of at least 20 MPa, measured according to the UNE-EN 310: 1993 standard - "Boards derived from wood - Determination of the modulus of elasticity in flexion and of the resistance to bending"; an internal cohesion of at least 0.31 MPa, measured according to the UNE-EN 319: 1993 standard - "Determination of the tensile strength perpendicular to the faces of the board"; and a coefficient of average thermal conductivity of 0.044 W / mK, measured according to the UNE-EN 12667: 2001 standard - "Construction materials - Determination of the thermal resistance by the method of the hot plate stored and the method of the flow meter of heat -Products of high and medium thermal resistance ", using 30x30 cm specimens with the help of a heat flow meter brand NETZSCH Instruments, Inc., USA.
    [0052]
    [0053] In turn, and using the same standards mentioned, the properties of the boards obtained from bark particles having an average density between 0.85 and 1.02 g / cm3 (preferably 0.91 g / cm3), a resistance to bending were measured static at least 18 MPa, an internal cohesion of at least 0.11 MPa and a mean thermal conductivity coefficient of 0.045 W / mK.
    [0054]
    [0055] In this way, due to the technical characteristics of the boards obtained by the claimed process, these can be of interest as elements with acceptable mechanical strength classified as type P1 "Boards for general use in a dry environment" according to the UNE-EN 312 standard , and that at the same time have low thermal conductivity.
    [0056]
    [0057] Additionally, the object of the invention is the use of the boards claimed for the production of construction elements with suitable mechanical properties for replace the boards commonly used in the state of the art or as thermal insulators.
    [0058]
    [0059] BRIEF DESCRIPTION OF THE DRAWINGS
    [0060] To complement the description of the invention and in order to help a better understanding of the characteristics thereof, the following figure is attached as an integral part of said description, with an illustrative and non-limiting character of the invention:
    [0061]
    [0062] Figure 1.- Representation of the structure of the macrophyte plant used in the process of the invention, where (1) is the marrow and (2) is the bark of the plant.
    [0063]
    [0064] PREFERRED EMBODIMENT OF THE INVENTION
    [0065] In a particular embodiment of the invention, the process for the manufacture of agglomerated particle boards without added adhesives can be carried out from dry reed (Schoenolectus caüfornicus) stems .
    [0066]
    [0067] First, the cortex (2) and medulla (1) tissues are separated by a blade.
    [0068]
    [0069] Then, the marrow is crushed until an average particle size of less than 2 mm is obtained, and the crust is crushed until an average particle size of less than 0.5 mm is obtained. The particles are dried separately at 100 ° C until a moisture content of 1% is obtained.
    [0070]
    [0071] The dried particles are arranged forming a blanket of marrow particles and a blanket of bark particles to which 1 and 2% free water, respectively, is added by spraying.
    [0072]
    [0073] Once the blankets are formed, they undergo a pressing process in a press of 40x60 cm at a temperature of 150 ° C and 3 MPa of pressure for 15 minutes, resulting in an agglomerated board of marrow particles and an agglomerated board of bark particles. After this time, the pressure is removed and the boards are left to cool horizontally.
    [0074] In a particular example of the invention, this process was carried out three times and the mechanical properties of the boards obtained from the process were analyzed.
    [0075]
    [0076] The boards obtained from particles of totora marrow reached a resistance to the average static flexure of 20 MPa and an average internal cohesion of 0.35 MPa.
    [0077]
    [0078] In turn, the boards obtained from bark particles reached an average static flexural strength of 11 MPa and an average internal cohesion value of 0.14 MPa.
    权利要求:
    Claims (7)
    [1]
    A process for the manufacture of agglomerated particle boards without adhesives added from at least one macrophyte plant whose stems are constituted by a central tissue or marrow constituted by an aerenchyma tissue surrounded by an external tissue or cortex, where said process it is characterized because it comprises:
    (a) separate the bark from the marrow of the plant;
    (b) once the cortex has been separated from the marrow, the marrow is crushed until obtaining an average particle size less than or equal to 2 mm and the crust is crushed until obtaining an average particle size less than or equal to 0.5 mm;
    (c) once crushed, the marrow and bark particles are subjected separately to a drying process until the moisture content in the case of the marrow particles is reduced to a moisture content of between 1% and 2%. % and in the case of bark particles up to a moisture content between 1% and 3%,
    (d) then, the dried particles are arranged forming a blanket of marrow particles to which is added between 1 and 2% free water and a blanket of bark particles to which is added between a 1 and 3% free water;
    (e) once the medullar particle blanket and the bark particle blanket are formed, they are subjected to a pressing process at a temperature between 130 and 160 ° C for a time of 10 to 20 minutes and a pressure of 1 to 4 MPa, giving rise to agglomerated boards of marrow particles and agglomerated boards of bark particles, which are allowed to cool to room temperature.
    [2]
    2. Process according to claim 1, wherein the separation of the bark and the marrow from the stems is done with the stems of the plant freshly cut or once dried.
    [3]
    3. Process according to claim 1 or 2, wherein the macrophytic plant is the totora or Schoenoplectus califomicus.
    [4]
    4. Agglomerated particle board from the marrow of a macrophyte plant obtained from a process according to any of claims 1 to 3, characterized in that it has an average density between 0.75 and 0.89 g / cm3 measured according to the standard UNE-EN 323: 1993; a resistance to static bending of at least 20 MPa, measured according to the UNE-EN 310: 1993 standard; an internal cohesion of at least 0.31 MPa, measured according to the UNE-EN 319: 1993 standard and a coefficient of average thermal conductivity of 0.044 W / mK, measured according to the UNE-EN 12667: 2001 standard.
    [5]
    5. Agglomerated particle board of the bark of a macrophyte plant obtained from a process according to any of claims 1 to 3, characterized in that it has an average density between 0.85 and 1.02 g / cm3 measured according to the UNE standard -EN 323: 1993, a resistance to static bending of at least 18 MPa, measured according to the UNE-EN 310: 1993 standard, an internal cohesion of at least 0.11 MPa, measured according to the UNE-EN 319: 1993 standard and a coefficient of average thermal conductivity of 0.045 W / mK, measured according to the UNE-EN 12667: 2001 standard.
    [6]
    6. Use of an agglomerated board according to claim 4 or 5 for the manufacture of a constructive element.
    [7]
    7. Use of an agglomerated board according to claim 4 or 5 for the manufacture of an insulating element.
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    同族专利:
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    ES315706A1|1964-07-22|1966-06-01|Boothe Miller Robert|Procedure for the manufacture of boards and similars from the bark of sugar cane. |
    US4025278A|1975-03-05|1977-05-24|Sydney Edward Tilby|Apparatus for fabricating boards from sugarcane rind fibers|
    US5284546A|1991-01-04|1994-02-08|Tilby Sydney E|Apparatus for manufacture of structural panel|
    WO1998048990A1|1997-04-30|1998-11-05|Tsuyoshi Kono|Boards produced with the use of grass plant lignin and process for producing the same|
    JP2003200407A|2001-10-24|2003-07-15|Shuichi Kawai|Binderless board and its manufacturing method|
    JP2007021972A|2005-07-20|2007-02-01|Matsushita Electric Works Ltd|Binderless board|
    ES2390853A1|2012-07-30|2012-11-19|Universidad Miguel Hernández De Elche|Method for manufacturing particleboard made of lignocellulose material|
    法律状态:
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    优先权:
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