Non-wood cellulose and its utilization methods

Abstract

The objective is to provide a method for effectively utilizing waste generated during the production of agricultural and marine products. [Solution] By extracting cellulose from agricultural and marine products with a high cellulose content through hydrothermal treatment, waste that was previously treated by incineration or other methods can be effectively utilized. The obtained cellulose can be mixed with thermoplastic resin to produce high-strength products.

Description

Technical Field

[0001] The present invention relates to cellulose extracted from non-wood biomass that becomes waste in biomass, particularly in the agricultural and fisheries industries, and a method for using the same.

Background Art

[0002] The utilization of biomass contributes to solving problems such as preventing global warming and forming a recycling-oriented society. Therefore, various methods for producing energy and products from biomass have been developed, but currently, energy production such as biomass power generation is the mainstay.

[0003] Despite the increasing utilization of biomass, most of the waste in the agricultural and fisheries industries is currently incinerated. For example, it is said that about 1.6 million tons of rice husks are generated annually in Japan and about 140 million tons annually worldwide. In Japan, although some are used for livestock housing materials, compost, etc., about 30% of rice husks are discarded and not effectively utilized. When incinerating discarded rice husks, there are not only environmental problems such as CO2 generation but also problems of high costs for treatment because they are general industrial waste. In addition, since rice husks contain about 20% silicon, they have poor combustibility and also cause problems of damaging incinerators. Therefore, many methods for recycling rice husks have been reported conventionally.

[0004] One method of utilizing rice hulls is to mix them with resin or other materials to manufacture molded products (Patent Documents 1 and 2). Patent Document 1 discloses a molded product in which recycled polyethylene resin is used as a binder resin and the mixture is formed into a predetermined shape by heat compression bonding. Patent Document 2 discloses a method for manufacturing a rice hull board by mixing rice hulls, paper, and resin and applying pressure. Since these molded products are manufactured by compression bonding, a certain degree of strength is obtained. However, while it is possible to manufacture simple shapes such as boards, it is difficult to manufacture complex shapes. If rice hulls are used as they are, it is not possible to manufacture products with complex shapes by injection molding. In addition, since the molded products retain the color of the rice hulls, there is a problem that the products that can be used as molded products are limited.

[0005] Furthermore, products made by crushing rice husks, mixing them with resin, and molding them are also sold as everyday items. Because the aim is to reduce the use of petroleum-derived plastics, these products typically contain a large amount of rice husks, usually around 30-55%. Due to the high rice husk content, it is difficult to control the strength of the product, so it is often offered as a product where strength is not required, such as cutlery. The limited uses of the product, the remaining color of the rice husks, and issues with smoothness can also create limitations when offering it as cutlery.

[0006] As a method of utilizing biomass other than rice husks, a plastic composite material has been disclosed in which woody and non-woody biomass are added to plastic at a rate of 70%, with the aim of utilizing unused biomass (Non-Patent Document 1). Woody biomass and crushed cocoa shells as a non-woody biomass are blended, and the fluidity and strength necessary for injection molding are evaluated. It has been reported that while the addition of cocoa shells, a non-woody material, improves fluidity, it also decreases strength.

[0007] The biomass utilization methods disclosed in Patent Documents 1 and 2, and Non-Patent Document 1, involve crushing the raw biomass and focusing on utilizing more than 50% biomass while reducing the amount of raw plastic. Therefore, there is room for improvement regarding the strength and manufacturability of the resulting plastic products, and their applications are limited.

[0008] In recent years, fiber-reinforced thermoplastics, which are thermoplastic resins to which reinforcing fibers are added, have been used in a wide range of fields as composite materials that achieve lightness, high strength, and high rigidity. As a reinforcing fiber used in fiber-reinforced thermoplastics, cellulose is attracting attention as a material other than glass fiber and carbon fiber. Fiber-reinforced thermoplastics mixed with cellulose have advantages that conventional resins with added reinforcing fibers do not have, such as excellent recyclability, lightness, and excellent surface smoothness. However, currently, highly refined cellulose made from wood is used as a raw material, and thermoplastic resins are not being manufactured using agricultural and marine waste. It is possible that using refined cellulose instead of raw crushed biomass could lead to the utilization of various types of waste.

[0009] Methods for extracting cellulose from agricultural waste are also beginning to be developed. Extracting and reusing useful substances from various agricultural and fishery wastes, including rice husks, is extremely important from the perspective of SDGs. Since agricultural waste, which is made from plant matter, contains cellulose in its cell walls, efforts are underway to extract cellulose and develop utilization methods that take advantage of its properties. One method for recovering useful substances such as cellulose from biomass and manufacturing products is the organosolve method. Patent documents 3 and 4 disclose a method for separating and utilizing cellulose, hemicellulose, and lignin, which are components of plant biomass. Furthermore, an apparatus for extracting useful substances such as polysaccharides containing hemicellulose and proteins from biomass using continuous subcritical treatment is disclosed (Patent document 5). [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] International Publication No. 2013 / 111370 [Patent Document 2] Japanese Patent Application Publication No. 9-1511 [Patent Document 3] Japanese Patent Publication No. 2017-000093 [Patent Document 4] Japanese Patent Publication No. 2017-002206 [Patent Document 5] International Publication No. 2024 / 210215 [Non-patent literature]

[0011] [Non-Patent Document 1] Ebihara, Noboru et al., 2014, Research Report of the Chiba Prefectural Institute for Industrial Support Technology, No. 11, pp. 11-15. [Overview of the Initiative] [Problems that the invention aims to solve]

[0012] The organosolve methods disclosed in Patent Documents 3 and 4 are very good methods for recovering useful substances from biomass, but because they use organic solvents, they have the problem of being too expensive when used as waste treatment. Patent Document 5 describes an apparatus developed by the present inventors, which can be used for various purposes, including enzymatic treatment. However, the production conditions for cellulose and the properties of the useful substances actually obtained have not been confirmed, so it was unknown what applications it could be used for.

[0013] The inventors have demonstrated that adding cellulose extracted by hydrothermal treatment to a thermoplastic resin at a low concentration of approximately 5-15% increases its rigidity. The objective of this invention is to provide a method for extracting cellulose from various agricultural and marine waste products and utilizing its properties. [Means for solving the problem]

[0014] This invention relates to the following non-wood cellulose and methods for utilizing it. (1) Cellulose produced by hydrothermal treatment using agricultural and marine waste as raw material, which improves rigidity when added to thermoplastic resins in a proportion of 5% to 51%. The inventors analyzed the properties of cellulose produced from agricultural and marine waste by hydrothermal treatment and found that adding it to thermoplastic resins can impart high rigidity to the resins. Here, improved rigidity refers to an improvement in the deformation resistance of the molded article obtained by adding cellulose to the resin. The improvements in the flexural modulus and tensile modulus, as well as the resulting increase in the maximum stress in bending and tensile tests, shown in the following examples, indicate an increase in structural strength. Since the properties of cellulose obtained from agricultural and marine products used as raw materials differ somewhat, it is possible to obtain desired thermoplastic resins by utilizing these properties.

[0015] (2) The cellulose according to (1), characterized in that the agricultural and marine waste is derived from rice, a grass plant, and is further rice husk. Cellulose can be obtained from various agricultural and marine waste products, but in Japan alone, approximately 1.6 million tons of rice husks are produced annually, and it is said that about 30% of this is discarded. Even incineration is problematic because the silica contained in rice husks damages incinerators. Producing cellulose from discarded rice husks would not only be useful but also extremely important from the perspective of SDGs.

[0016] (3) A thermoplastic resin composition containing cellulose according to (1) or (2). By adding cellulose produced by hydrothermal treatment from agricultural and fishery products waste to a thermoplastic resin, a resin with enhanced rigidity can be manufactured. For example, by adding cellulose obtained from rice husks as a raw material to a thermoplastic resin, a thermoplastic resin with higher breaking point stress and breaking point strain in a tensile test can be obtained compared to the case where softwood cellulose is added.

[0017] (4) A method for manufacturing cellulose from agricultural and fishery products waste, comprising pulverizing the agricultural and fishery products waste, and performing hydrothermal treatment to produce cellulose that imparts high rigidity when added to a thermoplastic resin. (5) The manufacturing method according to (4), wherein the temperature range of the hydrothermal treatment is 100°C or higher and less than 374°C, and when the agricultural and fishery products waste is rice husks, the amount of ash to be removed can be adjusted based on the calculation formula of y = -0.0923x + 31.425 (where x is the treatment temperature and y represents the treatment time when the ash content becomes 0). The inventors of the present invention adjusted cellulose by hydrothermal treatment from agricultural products and clarified its properties, and found that high rigidity can be imparted by adding it to a thermoplastic resin. In addition, it was clarified that there is a certain relationship between the hydrothermal treatment conditions and cellulose purity, and a relational expression based on the treatment temperature and treatment conditions when using rice husks as a raw material was derived. As a result, it became possible to adjust the ash content to be removed and obtain cellulose of a desired purity.

Brief Description of the Drawings

[0018] [Figure 1] A diagram showing the relationship between the treatment time and the ash content in hydrothermal treatments at different temperatures. [Figure 2] A diagram showing the relationship between the temperature conditions and the treatment time when the ash content becomes 0 by hydrothermal treatment.

Embodiments for Carrying Out the Invention

[0019] The following discussion will primarily focus on cellulose derived from rice husks, but it goes without saying that other biomass materials can also be utilized, each taking advantage of its unique properties. Since the use of wood cellulose is already progressing, this discussion will focus on non-wood cellulose obtained from agricultural and marine waste.

[0020] Agricultural waste can be preferably used because its cell walls contain a large amount of cellulose. In addition to rice hulls, other raw materials that can be used as cellulose raw materials include rice straw, wheat straw, and other parts of agricultural products that are discarded after harvesting, such as the stems and leaves of tomatoes and other crops, or the outer leaves of cabbage, or discarded plants such as bamboo that has been cut down due to its negative impact on the surrounding environment, such as abandoned bamboo forests. Furthermore, the shells of sea squirts, a type of aquatic product, are known to be rich in cellulose. Any waste with a high cellulose content can be used, regardless of whether it is agricultural or aquatic.

[0021] The present invention will be explained below with reference to data. The following examples mainly show cellulose extracted by hydrothermal treatment using rice husks as an example, and methods of using it, but the scope of the present invention is not limited to the raw materials shown in the examples.

[0022] It is preferable to pre-treat agricultural and marine waste, including rice husks, before hydrothermal treatment. For example, the following pre-treatment can be performed. The biomass used as raw material is preferably crushed to a particle size of about 0.1 mm to 5 mm. In addition, sodium hydroxide or sodium silicate may be added before or after hydrothermal treatment to perform alkaline treatment. Alternatively, hydrothermal treatment may be performed under alkaline conditions. The alkaline treatment is carried out in an alkaline aqueous solution using sodium hydroxide, etc., adjusted to a pH of 12.0 or higher, preferably 12.5 or higher and 14.0 or lower (at 25°C, using the glass electrode method). When alkaline treatment is performed before or after hydrothermal treatment, it can be carried out at room temperature or higher, preferably 40°C or higher, more preferably 50°C or higher and 170°C or lower. There are two methods of treatment: low-temperature alkaline treatment and high-temperature alkaline treatment. Low-temperature alkaline treatment is carried out at a temperature range of 40°C or higher and 90°C or lower, preferably 50°C or higher and 80°C or lower, for 1 to 24 hours. High-temperature alkaline treatment is performed under sealed pressure at a temperature of 100°C to 200°C, preferably 120°C to 170°C, for 0.1 to 4 hours. The alkaline treatment conditions indicate a range in which pH and temperature can be adjusted independently, and it is not necessary to satisfy both simultaneously. In other words, the conditions can be appropriately selected according to the purpose of treatment, such as setting a high pH under low temperature conditions or a medium pH under high temperature conditions. After alkaline treatment, the material is neutralized with an acid such as citric acid, washed, dehydrated, and dried.

[0023] The hydrothermal treatment should be performed at a temperature of 100°C or higher, but below the critical point of 374°C, to promote the solubilization of hemicellulose. The pressure should be within the range of saturated water vapor pressure or 50 MPa. After solubilization of hemicellulose, solid-liquid separation operations, including centrifugation and reverse osmosis membrane treatment, are performed to separate the components. The solubilized cellulose can be further concentrated by distillation. Furthermore, this method allows for the separation of cellulose fraction from proteins, silica, ash, etc.

[0024] [Example 1] Production of rice husk cellulose Rice husk cellulose was prepared and its components analyzed as follows: Rice husks obtained from Fukushima Mirai Agricultural Cooperative were crushed and added to water to a substrate concentration of 10% by mass. The resulting aqueous dispersion was treated at 180°C for 2 hours, and the resulting solution was centrifuged at 3,000G using a centrifuge (screw decanter manufactured by Saito Centrifuge Industry Co., Ltd.) to obtain the solid component. After repeating this process 6 times, the solid component was dried at 60°C for 300 minutes to obtain cellulose.

[0025] Table 1 shows the composition of rice husk cellulose extracted by hydrothermal treatment (hydrothermal treated product) and the raw material, rice husks. Both the rice husk raw material and the hydrothermal treated product show the proportion of each analytical item in the dried standard. Analysis was performed using the NREL method (National Renewable Energy Laboratory method) to measure cellulose, hemicellulose, and lignin. In the NREL method, hemicellulose components such as xylan and mannan are quantified independently of cellulose-derived glucans. Therefore, to avoid analytical overlap with cellulose, the fraction excluding hemicellulose is defined as lignocellulose.

[0026] [Table 1]

[0027] As shown in Table 1, hydrothermal treatment of rice hulls removes ash and yields a cellulose fraction with a high lignocellulose content. Rice hulls consist mostly of cellulose, hemicellulose, and lignin, which make up the cell walls. The components other than cellulose, hemicellulose, and lignin in the rice hull raw material are ash, including silica, which was present at 19.53% in the rice hulls. After hydrothermal treatment, the ash content decreased to 1.17%, which is about 6% of the ash content before treatment. Furthermore, silica could be reduced to below the detection limit. Hemicellulose was also reduced to about 20.0% of the pre-treatment level by hydrothermal treatment.

[0028] In the case of rice husks as raw material, the ash content is high, and within that ash, the silica content is particularly high. The types of impurities present in large quantities depend on the type of agricultural or marine product used as raw material. In the case of rice husks, the protein and sugar content is low, but these can be removed by hydrothermal treatment, increasing the lignocellulose content. Furthermore, depending on the treatment conditions such as the temperature and time of the hydrothermal treatment, it is possible to fractionate the cellulose from organic matter such as ash, protein, and sugar, and reuse each component.

[0029] As will be discussed later, when purifying cellulose, impurities such as ash can be controlled by selecting appropriate conditions for the hydrothermal treatment, such as temperature and time. The cellulose obtained in Table 1 was obtained by hydrothermal treatment at a relatively high temperature and for a long time, but cellulose containing silica can also be obtained by treating it under milder conditions. Similarly, the hemicellulose content can also be adjusted to the desired level by selecting appropriate conditions for the hydrothermal treatment, such as temperature and time.

[0030] The silica contained in cellulose is said to impart favorable properties to the compounding properties with resins and the stretchability of resin materials. The silica content of rice husk cellulose can be adjusted by the hydrothermal treatment conditions, so the cellulose should be adjusted according to the intended use. Furthermore, even when using raw materials other than rice husks, the content of organic substances such as proteins contained as impurities can be adjusted by the hydrothermal treatment conditions.

[0031] Although alkaline treatment is not performed here, if alkaline treatment is performed as a pretreatment, the amount of residual ash can be reduced by the number of washes after alkaline treatment, and the purity of lignocellulose can be increased even under relatively low temperature and short-duration hydrothermal treatment conditions. Furthermore, if alkaline treatment is performed to remove ash, silica can be recovered as a solid by agglomeration during the neutralization process.

[0032] [Example 2] Production of tomato leaf cellulose Another example of cellulose purification by hydrothermal treatment is shown. Tomato leaf waste (leaves) from tomato harvesting was crushed and placed in water at a 10% substrate concentration. Ultrasonic irradiation was performed for 10 minutes using an ultrasonic homogenizer (Nippon Seiki Seisakusho Co., Ltd.) to obtain the tomato leaf raw material. The results of hydrothermal treatment at 180°C for 1 hour are shown (Table 2). The analytical values ​​for the tomato leaf raw material are before hydrothermal treatment, and the analytical values ​​for the hydrothermal treated material are after hydrothermal treatment.

[0033] [Table 2]

[0034] In the case of tomato leaves, hydrothermal treatment reduced pectin, hemicellulose, and ash content, increasing the cellulose content by up to 1.8 times and yielding cellulose with a purity of approximately 89%. Since tomato leaves have a high pectin content, it is also possible to reduce pectin and obtain more purified cellulose by performing enzyme treatment before or after hydrothermal treatment, for example.

[0035] [Example 3] Investigation of hydrothermal treatment conditions It is believed that higher temperatures and longer treatment times during hydrothermal treatment yield standards with higher cellulose purity. Therefore, rice husks were hydrothermally treated under various temperature and time conditions, and the ash content was measured. As shown in Example 1, in the case of rice husks, there is an inverse correlation between the decrease in ash content (silica and non-silica ash) and cellulose purity. Therefore, it is considered possible to estimate cellulose purity by measuring the amount of ash content.

[0036] Cellulose was prepared in the same manner as in Example 1, except that the substrate concentration was adjusted to 3% by mass and hydrothermal treatment was performed at temperatures of 100°C, 165°C, and 180°C with varying treatment times, and the ash content was measured (Figure 1).

[0037] Regardless of the processing temperature, the ash content decreases with processing time. Since there is an inverse correlation between ash content and cellulose purity, this indicates that higher purity cellulose can be obtained with longer processing times.

[0038] These results indicate that when hydrothermal treatment is performed at 100°C, it takes approximately 40 hours for the ash content to become zero, while at 165°C and 180°C it takes approximately 15 hours. Here, "zero ash content" means that, based on actual measurements, the ash content drops below the detection limit (less than 1% residual). The points at which the ash content becomes zero under the three temperature conditions were plotted, and an approximation formula was created (Figure 2). While these temperatures were determined solely from experimental values, the treatment time approaches zero at 340°C.

[0039] Based on this data, for example, if we want to produce cellulose with 50% of the ash removed at 100°C, we can see from the relationship between processing time and temperature that we should process it for 11 hours. By controlling the amount of ash removed, it is possible to prepare cellulose of the desired purity, but since agricultural and marine products are used as raw materials, it is necessary to consider that there may be an error of a few percent.

[0040] [Example 4] Characteristics of rice husk cellulose It has already been disclosed that cellulose can be extracted from wood-based biomass, such as wood chips, and added to resin to obtain a high-strength thermoplastic resin. The above analysis revealed that hemicellulose can be solubilized and removed by hydrothermal treatment. By removing hemicellulose, the cellulose content increases, and in the case of rice husk cellulose, the lignocellulose content also increases. Therefore, it is expected that this will be advantageous in the production of thermoplastic resins in terms of improved interfacial affinity with the resin, improved balance of mechanical strength and rigidity, improved thermal stability and moldability, and dimensional stability due to reduced hygroscopicity. Thus, we investigated the properties obtained by adding rice husk cellulose, a non-wood cellulose, to resin.

[0041] Here, we analyze the physical properties of resins obtained by kneading polypropylene, low-density polyethylene, and high-density polyethylene with the obtained non-wood cellulose. However, the resins used for kneading are not limited to these, and any thermoplastic resin may be used. Such resins include, for example, biodegradable resins such as polylactic acid and polyhydroxyalkanoates; polyolefin resins such as low-density polyethylene, medium-density polyethylene, and high-density polyethylene; chlorine-containing resins such as polyvinyl chloride (PVC) and polyvinylidene chloride (PVdC); fluorine-containing resins such as tetrafluoroethylene resin and ethylene-tetrafluoroethylene copolymer resin; addition-type thermoplastic resins other than those listed above, such as ethylene vinyl acetate resin, polystyrene resin, and ABS resin; various polyamide resins such as nylon 6 and nylon 66, and copolymers thereof; polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); and various polyester resins such as polyesters copolymerized with diol components such as diethylene glycol, neopentyl glycol, and polyalkylene glycol, or dicarboxylic acid components such as adipic acid, sebatic acid, and phthalic acid, as well as liquid crystal polyesters; and condensation thermoplastic resins other than condensation thermoplastic resins such as polyamide-imide resin and thermoplastic polyimide.

[0042] Furthermore, when manufacturing the product, fillers, flame retardants, antioxidants, clarifiers, plasticizers, antistatic agents, compatibilizers, nucleating agents, ultraviolet absorbers, weathering agents, heat stabilizers, light stabilizers, binders, antiblocking agents, lubricants, neutralizing agents, crystallization accelerators, colorants, foaming agents, waterproofing agents, water repellents, antibacterial agents, antifogging agents, impact resistance enhancers, and the like can be added as needed.

[0043] Here, 90 parts by mass of polypropylene (PP, Novatec PP manufactured by Nippon Polypropylene Co., Ltd.) (95 parts by mass in the control example without cellulose) were mixed with 5 parts by mass of maleic anhydride-modified polypropylene (MAPP, Kayabrid 006PP manufactured by Kayaku Akzo Co., Ltd.), and 5 parts by mass of rice husk cellulose (hydrothermally treated) and, as a comparative example, coniferous tree pulp cellulose (manufactured by Marusumi Paper Co., Ltd.) were added to prepare sample molded bodies.

[0044] After mixing each formulation, pellets were prepared by kneading the mixture using a kneading machine (Toyo Seiki Seisakusho Co., Ltd., resin kneading test equipment) at a molding temperature of 180°C. The pellets were then molded into sample molded bodies using a small injection molding machine (Lambaldie, Babyplast 6 / 10), and the physical properties of the molded bodies were measured (Table 3).

[0045] Various physical properties were measured as follows. (1) Tensile test The modulus of elasticity, stress at fracture, strain at fracture, maximum stress, and maximum strain of each sample were measured using a Shimadzu Autograph AGC-5kNG under tensile testing conditions of 10 mm / min. (2) Bending test The modulus of elasticity, maximum stress, and maximum strain of each sample were measured using a Shimadzu Autograph AGC-5kNG under conditions of a bending test speed of 5 mm / min.

[0046] [Table 3]

[0047] Cellulose-free polypropylene showed a significantly larger maximum strain compared to polypropylene with added cellulose. However, no significant differences were observed in the bending test results among the three materials. Rice husk-cellulose-added polypropylene, shown as Example 1, did not show a significant difference in maximum stress and maximum strain in the tensile test compared to coniferous pulp-cellulose-added polypropylene in Comparative Example 1. However, a significant difference was observed in fracture stress and fracture strain, with rice husk cellulose showing 15 times and more than 3 times the strength of coniferous pulp cellulose, respectively. The increase in fracture stress and fracture strain in the tensile test due to the addition of rice husk cellulose indicates an improvement in rigidity, specifically an improvement in the balance between deformation resistance and fracture resistance. In other words, it indicates that adding rice husk cellulose to polypropylene compared to coniferous pulp results in a "hard and tough material." That is, when using thermoplastic resin mixed with rice husk cellulose for injection molding, etc., it can be said that flexible material design is possible.

[0048] A thermoplastic resin was manufactured by kneading crushed rice husks into resin, and its physical properties were compared by bending tests (Table 4).

[0049] [Table 4]

[0050] Resin samples were prepared by adding 5% of either crushed rice husks or rice husk cellulose. For comparison, a resin material was also prepared by adding 5% of reagent cellulose (Merck microcrystalline cellulose) in the same manner. Polypropylene was prepared in the same manner as above, with MAPP added as a dispersant, while low-density polyethylene (Asahi Kasei Suntech LD) was prepared without a dispersant.

[0051] Although LDPE and PP resins each have their own characteristics, it was found that the strength enhancement by additives showed a similar trend. Compared to samples with only resin, samples with crushed rice husks, rice husk cellulose, and reagent cellulose added all showed higher values ​​for both elastic modulus and maximum stress. Furthermore, the sample with rice husk cellulose added had higher strength in both elastic modulus and maximum stress compared to the sample with crushed rice husks and the sample with reagent cellulose added. The increase in maximum stress and elastic modulus in the bending test both indicate improved rigidity.

[0052] Furthermore, in samples to which crushed rice husks have been added, the silica contained in the rice husks remains intact. As mentioned above, if rice husks are burned as is, the silica they contain can cause damage to the incinerator, but if resin materials to which crushed rice husks have been added as is are to be incinerated after use, the silica may cause damage to the incinerator. If rice husks are only crushed, the time and cost of hydrothermal treatment to produce cellulose can be saved. Therefore, there is an advantage in that resin products can be manufactured at a low cost, but rice husk cellulose-added samples are superior not only in terms of strength but also in terms of low silica content.

[0053] [Example 5] Characteristics of cellulose produced from agricultural and marine waste other than rice husks Cellulose was extracted from agricultural and marine waste products other than rice husks, and their physical properties were compared. Resin pellets were prepared from rice husks, tomato leaves, bamboo, and sea squirt shells (a marine waste product). 51% of the cellulose fraction extracted from each material was added to polypropylene or high-density polyethylene, and the physical properties of the materials were measured (Tables 5 and 6). Cellulose extraction from each raw material was performed by hydrothermal treatment, similar to the method used for rice husks.

[0054] [Table 5]

[0055] When cellulose obtained from various raw materials was added to polypropylene, the flexural strength, flexural modulus, and tensile strength increased in all cases. On the other hand, the tensile elongation was lower when cellulose was added. This indicates that a harder resin can be obtained by adding cellulose. Regarding Izod impact strength, when rice husk, tomato, and bamboo cellulose were added, the values ​​were lower compared to when no cellulose raw material was added, but the resin with sea squirt shell cellulose added showed a slightly higher value. Although there were no significant differences in flexural strength, flexural modulus, and tensile strength depending on the cellulose raw material, these properties can be utilized in the manufacture of resin products by injection molding, etc.

[0056] [Table 6] Tensile strength and tensile elongation were not measured for the sea squirt shells.

[0057] When cellulose obtained from various raw materials was added to high-density polyethylene, the flexural modulus was higher than that without cellulose, and the flexural strength was similar or slightly lower, regardless of the type of cellulose added. Furthermore, the tensile elongation was low in all cases, but the tensile strength was higher when tomato leaf or bamboo cellulose was added compared to the resin alone, and lower when rice husk cellulose was added. These cellulose-added resin materials can be used to manufacture resin products that utilize their specific properties through injection molding, extrusion molding, etc.

[0058] As shown above, cellulose obtained from agricultural and marine waste by hydrothermal treatment can reduce impurities contained in the waste. Furthermore, by adding it to thermoplastic resins, it can impart physical properties comparable to reagent cellulose and coniferous cellulose. Here, cellulose obtained from agricultural and marine waste is added to the resin at a ratio of 5-51%, but sufficiently high strength can be obtained even at a ratio of 5% to 15%. Depending on the type of product to be manufactured, the agricultural and marine waste to be used as raw material should be selected, the cellulose that provides the desired strength should be selected, and then the thermoplastic resin should be manufactured by adding the cellulose in an appropriate ratio. It has become clear that the properties of cellulose obtained from agricultural and marine waste differ depending on the raw materials used for extraction, and that different physical properties can be obtained when added to resin. The properties of the cellulose obtained from each raw material can be utilized for reuse.

Claims

1. Using agricultural and marine waste as raw materials, Cellulose produced solely by hydrothermal treatment, Cellulose that improves rigidity in bending tests when added to thermoplastic resins in a ratio of 5% to 51%.

2. The cellulose according to claim 1, characterized in that the aforementioned agricultural and marine waste is a plant derived from a grass.

3. The cellulose according to claim 2, characterized in that the aforementioned agricultural and marine waste is derived from rice.

4. The aforementioned agricultural and marine waste is derived from rice, The cellulose according to claim 3, characterized in that it is rice husk.

5. A thermoplastic resin composition containing cellulose according to any one of claims 1 to 4.

6. A method for producing cellulose from agricultural and marine waste, Crushing agricultural and marine waste, By performing hydrothermal treatment, A method for producing cellulose that imparts high rigidity to thermoplastic resins, as measured by bending tests, when added to them.

7. The temperature range for the aforementioned hydrothermal treatment is 100°C or higher and less than 374°C. Agricultural and marine waste is rice husks, Based on the formula y = -0.0923x + 31.425 (where x is the processing temperature and y is the processing time at which the ash content becomes 0), The manufacturing method according to claim 6, which allows for adjustment of the amount of ash to be removed.

Images