Method for manufacturing lightweight wood composites using sunflower and miscanthus stalks

Abstract

Method for manufacturing lightweight wood composites using sunflower and miscanthus stalks involves the following steps: producing wood chips and particles from sunflower and miscanthus stalks, drying the chips, mixing the chips with adhesive, forming a chip mat, pre-pressing it, and pressing it. The chip mat is formed as a three-layer structure. The two outer layers are formed from wood chips, while the inner layer is formed by mixing wood chips with sunflower and miscanthus particles in a mass ratio selected from the following range, %: 50:25:25, 25:50:25, or 25:25:50.

Description

The utility model belongs to the woodworking industry, in particular to manufacturing technologies wood composites (particle board, oriented strand board (OSB), fiberboards, wood-polymer boards, etc.) with reduced density, and can be used in the production of construction, heat-insulating and furniture board materials, household goods or industrial use, etc. Particleboard (PCB) is one of the main wood composites in world trade. In recent years global demand and production of JVs have increased due to factors such as relatively low cost, satisfactory physical and mechanical properties, high demand for wood composites and the presence of a large quantity of raw materials. Today, the traditional raw materials for the production of wood composites are wood. Glue and wood chips are the two main components of the JV. The cost of the raw materials used, namely glue and wood chips, accounts for the majority of the cost of the final SP. The total cost materials accounts for 40-60% of the total cost of production. Other main cost components, such as energy, labor and processing costs of the SP, are about 15-20%, 5-20% and 25-30%, respectively. Wood chips are the second most expensive component after glue in the production of JV, on which accounts for approximately 20% of total production costs. Thus, it is an undeniable fact that that the cost of materials, which includes the cost of glue and wood chips, is often more half of the total cost of production. However, if the prices of wood raw materials in recent years increased, the estimated price of agricultural waste is at least 50% lower than the price wood chips. As a result, replacing wood chips with alternative, non-wood raw materials can lead to significant cost savings. Optimization of available wood and lignocellulosic raw materials, as well as the search for alternative natural raw materials obtained from renewable agricultural waste or annuals plants, to replace wood in the production of JV is a viable strategy for reducing negative impact on the environment and increasing the resource efficiency of woodworking industry. Agricultural waste is a huge pool of unused biomass resources. Thus, despite the fact that wood remains the traditional raw material for production SP, agricultural waste fibers and annual plants are becoming popular for production of composite panels for the purpose of sustainable forest management. The density of traditional SP is usually 600-750 kg / m³. According to the CEN / TS standard 16368:2014, lightweight boards are considered to be boards with a density of less than 600 kg / m³. Lightweight SPs have a number of advantages for manufacturers, designers and end users compared to standard slabs. Their use expands the possibilities of interior design (use of more massive elements, reducing the load during installation), simplifies installation and processing, facilitates transportation and machining, and also allows to reduce transportation and raw material costs. The weight of the material is the third most important criterion for consumers when choosing furniture - after design and cost. One important approach to reducing the density of wood-based panels is to use raw materials from annual and perennial plants, as well as a combination of wood with fibrous plant materials materials of agricultural origin. Thus, one of the directions of reducing wood costs in the production of SP and reducing their density is the use of agricultural waste and annual plants. One such agricultural waste that can replace wood is stalks. sunflower (Helianthus annuus L.), a by-product of sunflower cultivation. Sunflower is the fourth largest source of oilseeds worldwide with over 25 million hectares cultivated land. It is estimated that from each hectare of harvested sunflower, 3-7 tons can be obtained dry biomass, including plant heads and stems. Its cultivation volumes are increasing annually by 10-20% due to increased needs in vegetable oil production, which leads to a significant increase in sunflower stem accumulation. According to the Food and Agricultural Organization According to the United Nations, in 2023, approximately 58,574,867 tons of sunflower seeds were harvested worldwide, of which about 42,162,800 tons (72% of world production) were produced in Europe and about 12,759,690 tons (22% of world production and 30% of European production) in Ukraine. One of the annual plants that can replace wood is the stems of miscanthus (Miscanthus sinensis giganthus). Miscanthus, as a genus of plants, includes perennial woody rhizomatous grasses similar to bamboo, native to tropical and subtropical regions of Asia and Southeast Africa. The plant has usual height from 1.5 m to 4 m, and some species can even reach a height of 6-7 m, diameter stems - from 1 to 2 cm. According to the chemical composition, miscanthus contains approximately 38% cellulose, 17% lignin and 21% hemicellulose is close to wood. With a cultivation area in Europe of about 40 000 ha, thick-stemmed knotty woody miscanthus with a dry matter yield of up to 40 t / ha can be a very attractive resource in the production of wood composites. Therefore, it can be assumed that Miscanthus is a resource suitable for wood composites, demonstrating acceptable performance characteristics. A known method of manufacturing particle boards using straw, which includes the operations preparation of chips, drying of chips, mixing of chips with glue, shaping and pressing chip carpet, pressing of boards, according to which the outer layers of the boards are formed from wood particles, and the inner layer is made of wood particles with the addition of up to 20% particles from wheat straw, and urea-formaldehyde resin was used as the glue [1]. The disadvantage of the known method is unsatisfactory bonding strength and low content of straw particles (up to 20%) due to poor bonding with urea-formaldehyde adhesives. A known method of manufacturing three-layer particle boards with a density of 700 kg / m3 from a mixture of particles sunflower and pine stalks in different ratios of sunflower stalk particles to pine particles pine wood 100:0, 25:75, 50:50, 75:25 and 0:100, glued with urea-formaldehyde glue [2]. The disadvantage of the known method is the high density of the plates, which increases the weight of the material and complicates work with it. him, as well as his transportation. A known method of manufacturing single-layer particle boards with a density of 600 kg / m3 from particles miscanthus, using methylene diphenyl dicyanate (MDI) as a glue [3]. The disadvantage of the known method there is a high density of the plates, which increases the weight of the material and makes it difficult to work with it, as well as its transportation; use of expensive isocyanate glue (MDI) and its high content (4 and 6%), low mechanical properties compared to wood, which collectively leads to an increase in the price of the finished product products. The utility model is based on the task of improving the method of manufacturing lungs wood composites through the rational use of particles from sunflower stalks and miscanthus in the structure of the composite in order to reduce its density and improve its operational properties properties. In addition, in the method of manufacturing lightweight wood composites, part of the wood shavings are replaced with sunflower and miscanthus particles, expanding the raw material base for production of composites, valuable wood raw materials are saved, the cost of finished products is reduced composites. The task is solved by the method of manufacturing lightweight wood composites from using sunflower and miscanthus stems, which includes operations for making wood pulp shavings and particles from sunflower and miscanthus stems in the form of shavings, drying of shavings, mixing chips with glue, forming a chip carpet, pressing it and pressing it, according to utility model, the chip carpet is formed into a three-layer structure, with the two outer layers formed from wood chips, and the inner layer is formed by mixing wood chips with sunflower and miscanthus particles in a mass ratio selected from the range, %: 50:25:25, 25:50:25 or 25:25:50. Method for manufacturing lightweight wood composites, in particular lightweight particle boards with a density 550 kg / m³ using sunflower and miscanthus stems is carried out as follows. Wood raw materials and sunflower and miscanthus stems are crushed for production wood chips and sunflower and miscanthus particles and dried. Dried wood chips and sunflower and miscanthus particles are fed to the mixing operation. During the mixing process, urea-formaldehyde glue is applied to the particles. After mixing with the glue, a three-layer chip carpet, with the two outer layers formed from wood chips, and the inner layer is formed by mixing wood chips with sunflower particles and miscanthus at a mass ratio of wood chips to sunflower and miscanthus particles, selected from the range 50:25:25%, 25:50:25% or 25:25:50%. The ratio between external and inner layers is 33:67%. The formed carpet is pressed and sent for operation Pressing of plates. Pressing of plates is carried out under a pressure of 2.5 MPa and a temperature of 190 C. Samples for mechanical testing were cut from the pressed plates. The strength was determined during static bending (according to DSTU EN 310: 1993), modulus of elasticity during static bending (according to DSTU EN 310: 1993), tensile strength perpendicular to the plane of the plate (according to DSTU EN 319: 1993). The values ​​of the determined indicators were compared with the requirements of international standards for light particle boards (EN 16368 and ANSI A208.1). The mechanical properties of the resulting boards are given in the table. As can be seen from the table, replacing part of the wood chips in the inner layer with particles sunflower and miscanthus improves the mechanical properties of particle boards. The highest strength values at static bending (8.6 MPa), modulus of elasticity (1848 MPa) and tensile strength perpendicular to the plane of the plate (0.37 MPa) was obtained for the ratio of wood chips to sunflower and miscanthus particles in the inner layer of the plates as 25:25:50%. In addition, under such the ratio between the particles, the static bending strength and the elastic modulus of the plates are higher, than for boards whose inner layer is made entirely of wood, sunflower or miscanthus. Regarding tensile strength perpendicular to the plane of the plate, then for the same ratio of values strengths are higher than for boards whose inner layer is made entirely of wood, but lower, a knife for plates whose inner layer is made entirely of sunflower or miscanthus. According to the values ​​of the strength during static bending of plates, the inner layer of which is formed from a mixture wood chips and sunflower and miscanthus particles, meet the requirements for LP1 and LP2 type boards (except for the ratios 50:25:25 % and 25:50:25 %) according to EN 16368 and LD-1 and LD-2 according to ANSI A208.1; for the values ​​of the modulus of elasticity - the requirements for LP1 and LP2 type plates according to EN 16368 and LD-1 and LD-2 according to ANSI A208.1; by tensile strength values ​​perpendicular to the plane of the plate - requirements for LP1 type plates according to EN 16368 and LD-1 and LD-2 according to ANSI A208.1. Table Comparative characteristics of the mechanical properties of the obtained lightweight plates with the requirements standards Indicator Correlation wooden shavings and particles sunflower and miscanthus Proposed way Plates from 100% wooden shavings Requirements according to EN 16368 Requirements according to ANSI A208.1 type LP1 type LP2 type LD-1 type LD- 2 Tensile strength at static bending, MPa 50:25:25 7.7 8.0 4.0 8.0 3.0 5.0 25:50:25 7.8 25:25:50 8.6 0:100:0 8.1 0:0:100 7.8 Module elasticity, MPa 50:25:25 1679 1650 550 1000 550 1025 25:50:25 1712 25:25:50 1848 0:100:0 1853 0:0:100 1772 Tensile strength at stretching perpendicular to plate plane, MPa 50:25:25 0.34 0.34 0.28 0.40 0.10 0.15 25:50:25 0.37 25:25:50 0.37 0:100:0 0.41 0:0:100 0.40 Higher values ​​of tensile strength perpendicular to the plane of the plate (0.37 MPa) for plates with an inner layer formed with a higher content of sunflower and miscanthus particles than for slabs (50:25:25) with a higher content of wood chips (0.34 MPa), indicate that sunflower particles and miscanthus stick together better than with wood chips. Boards with an inner layer formed only from sunflower particles demonstrate higher mechanical properties compared to plates whose inner layer is formed only from miscanthus particles. In addition, the plates with an inner layer formed only from sunflower particles or miscanthus particles provide higher mechanical properties than boards with an inner layer of wood particles. Because of this, the outer layer is formed from wood particles, and the inner layer is formed from a mixture of wood chips and particles sunflower and miscanthus for the ratio of wood chips to sunflower and miscanthus particles, as 25:25:50%. The advantage is that the corresponding lightweight wood composite is light in weight, but despite this maintains sufficient mechanical stability. In addition, the process of manufacturing lightweight wood composite is simple; there is no need to re-equip existing manufacturing facilities lightweight wood composite. The claimed method can be implemented in industrial conditions with using standard chipboard manufacturing equipment and is suitable for serial production. Therefore, the proposed method of manufacturing lightweight wood composites allows to expand raw material base for their production by involving agricultural waste and annual plants, namely sunflower and miscanthus stems, to reduce the cost of finished boards and, accordingly, save valuable wood raw materials, which is extremely relevant for small-scale forests regions of Ukraine. Another advantage of using sunflower and miscanthus stems is that it is a cheap and annually renewable type of raw material. Sources of information: 1. Utility model patent No. 21441, Ukraine, MPK B27 N 3 / 00. Method of manufacturing chipboard plates / Bekhta P.A., Salabai R.G. - Application number u200610411; declared on 02.10.06; published on 15.03.07, Bulletin No. 3. 2. Cengiz Guler, Ibrahim Bektas, Hulya Kalaycioglu. The experimental particleboard manufacture from sunflower stalks (Helianthus annuus L.) and Calabrian pine (Pinus brutia Ten.). Forest Products Journal, 2006, 56(4):56-60. 3. Petr Klímek, Rupert Wimmer, Peter Meinlschmidt, Jozef Kúdela. Utilizing Miscanthus stalks as raw material for particleboards. Industrial Crops and Products, 2018, 111, 270-276. https: / / doi.org / 10.1016 / j.indcrop.2017.10.032.

Claims

Method for manufacturing lightweight wood composites using sunflower stalks and miscanthus, which includes operations for the production of wood chips and particles from the stems sunflower and miscanthus in the form of chips, drying the chips, mixing the chips with glue, forming a chip carpet, pressing it and pressing it, which is different in that the chip carpet is formed in three layers, with the two outer layers forming made of wood chips, and the inner layer is formed by mixing wood chips with sunflower and miscanthus particles in a mass ratio selected from the series, %: 50:25:25, 25:50:25 or 25:25:50.