Method for producing fibrous biomass, including physical treatment process

Abstract

The present invention relates to a method for producing fibrous biomass, including a hydration grinding process and a physical treatment process, the method comprising the steps of: pretreating and grinding herbaceous biomass and supplying same to a hydration extruder; supplying, to a disk refiner, the resulting hydrated biomass extrudate that has undergone hydration grinding by the hydration extruder; and physically treating the hydrated biomass extrudate by controlling the solid-to-liquid ratio of the disk refiner. The fibrous biomass produced by the method is suitable for use as a high-strength reinforcing material in a biodegradable resin composition.

Description

Method for producing fibrous biomass including a physical treatment process

[0001] The present invention relates to a method for producing fibrous biomass including a hydropulverization process and a physical treatment process, and is suitable for use as a high-strength reinforcing material in a biodegradable resin composition.

[0002] In the case of natural fibers in the form of additives previously developed for use in plastic composites, technological development has been focused solely on particle size through simple grinding, and as a result, there is an inevitably problem of deterioration in physical properties as the plastic resin replacement rate increases.

[0003] Research on natural fibers that can replace existing biodegradable resins such as polylactic acid (PLA) has suggested using expensive, high-tensile strength fibers (such as jute, flax, hemp, kenaf, and sisal) or fibers with low cost but low tensile strength (such as oil palm, elephant grass, and baggage) through chemical treatment.

[0004] For example, Korean Patent Publication No. 10-2012-0003762 discloses a method of producing microcrystalline cellulose (MCC) by crushing hemp stems into 150-200 ㎛ sizes, treating them with caustic soda, and then decomposing them with concentrated sulfuric acid, and a method of producing microcrystalline cellulose (MCC) by pre-processing the crushing with a physical treatment method and then treating them with sulfuric acid. In addition, Korean Patent Publication No. 10-2012-0003762 discloses a method of producing a composite material and a molded product by mixing 5-30 wt% of cellulosic fibers (wood, flax, hemp, jute, wheat straw, rice straw, pulp, etc.) and 1-20 wt% of polymer fibers (PVA, PET, PA, etc.) based on the total weight of the composite material in a twin-screw extruder. However, there is a limitation that the plastic resin replacement rate is low.

[0005] Therefore, there is a need for the development of a natural fiber pretreatment method and its utilization technology that can control factors that can affect the properties of the composite, such as the aspect ratio, crystallinity, and chemical composition of the fiber, without separate chemical treatment.

[0006] The purpose of the present invention is to provide a method for producing fibrous biomass that can control the aspect ratio, crystallinity, chemical composition, etc. of the fiber without chemical treatment.

[0007] Another object of the present invention is to provide a high-strength fibrous material reinforcing material by optimizing the physical pretreatment process conditions of natural fibers.

[0008] Another object of the present invention is to provide a high-strength biodegradable resin composition comprising fibrous biomass pretreated by a physical treatment process.

[0009] One aspect of the present invention provides a method for producing fibrous biomass, comprising the steps of pre-processing and crushing herbaceous biomass and supplying it to a hydroextruder; supplying the hydroextruded biomass crushed in the hydroextruder to a disk refiner; and physically treating the hydroextruded biomass by controlling the solid-liquid ratio of the disk refiner.

[0010] In an embodiment, the herbaceous biomass may be one or more selected from hemp, sorghum, jute, sweet corn bagasse, giant reed, and EFB, but is not limited thereto.

[0011] In an embodiment, the pretreatment grinding may be performed by grinding the herbaceous biomass into an average size of 1 mm to 10 mm using a cutting mill.

[0012] According to an embodiment, the temperature of the water injected for the hydrolysis grinding is 100°C or lower, and the biomass injection rate may be in the range of 5 kg / h to 20 kg / h, but is not limited thereto.

[0013] In an embodiment, the biomass hydration extruder may be a twin-extruder including a front screw, a kneading block, and a rear screw.

[0014] According to an embodiment, the screw speed of the twin-screw extruder may be in the range of 150 rpm to 200 rpm, but is not limited thereto.

[0015] In an embodiment, the solid-liquid ratio may be in the range of 1:7 to 1:10, but is not limited thereto.

[0016] In an embodiment, the aspect ratio of the fibrous biomass may be in the range of 3.5 to 6.0, and the average particle thickness may be in the range of 10 to 25 μm.

[0017] According to an embodiment, the particle size distribution of the fibrous biomass may be in the range of 1 to 3, and the crystallinity may be in the range of 45% to 60%.

[0018] Another aspect of the present invention provides a biodegradable resin composition comprising 20 to 40 wt% of the fibrous biomass and 60 to 80 wt% of the biodegradable resin.

[0019] In an embodiment, the biodegradable resin may be selected from the group consisting of, but is not limited to, polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polycaprolactone (PCL), polyglycolic acid (PGA), polyhydroxyalkanoate (PHA), polyhydroxy butyrate (PHB), copolymers thereof, and mixtures thereof.

[0020] According to an embodiment, the tensile strength of a molded product manufactured using the biodegradable resin composition may be in the range of 75 to 85 MPa.

[0021] According to an embodiment, the flexural strength of a molded product manufactured using the biodegradable resin composition may be in the range of 106 to 120 MPa.

[0022] According to an embodiment, the impact strength of a molded product manufactured using the biodegradable resin composition may be in the range of 20 to 30 J / m.

[0023] According to the present invention, a high-strength fibrous reinforcing material can be manufactured by optimizing the physical pretreatment process conditions of natural fibers such as hemp or ramie. The present invention provides a method for manufacturing fibrous biomass by introducing a physical treatment process through the control of the solid-liquid ratio as a natural fiber pretreatment method, thereby controlling not only the particle size of the natural fiber but also factors that can affect the physical properties of the composite, such as the aspect ratio, crystallinity, and chemical composition of the fiber.

[0024] The present invention utilizes a low-cost process byproduct (the pith discarded after removing hemp bast fibers) and introduces a grinding method that facilitates fiber fibrillation without additional chemical treatment. This allows for the creation of a biodegradable resin composition with superior physical properties compared to existing technologies. Therefore, the present invention proposes a method for incorporating natural fibers, such as hemp pith, currently underutilized, into biodegradable resin compositions to create high-strength, fibrous reinforcing materials.

[0025] The present invention has the advantage of simultaneously controlling the content of amorphous components (extracts and ash) as well as the average particle size and aspect ratio of hemp pith through a hydro-pulverization and physical treatment process using a twin screw extruder. Specifically, a continuous process was introduced to delignify and microfiberize natural fibers such as hemp pith or kenaf, and fibrillation of hemp pith was performed through a physical treatment process.

[0026] The present invention can produce fibrous biomass having a desired aspect ratio and crystallinity by controlling the solid-liquid ratio in the physical treatment process performed in a disc refiner, particularly after hydropulverization. Furthermore, a natural fiber has been developed that can increase the biomass content (by 30% or more based on product weight) while maintaining the strength of expensive biodegradable plastic resins (by 95% or more compared to neat PLA). Using the fibrous biomass pretreated according to the present invention as a substitute for biodegradable resins can provide a biodegradable resin composition with excellent mechanical properties.

[0027] The present invention will be described in more detail below with reference to examples. However, the following examples are provided for illustrative purposes only to aid understanding of the present invention and are not intended to limit its scope. It should be understood that the present invention is susceptible to various modifications and implementations in various different forms, and encompasses all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0028] Additionally, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0029] The present invention relates to a method for producing high-strength fibrous biomass including a physical treatment process.

[0030] A method for producing fibrous biomass according to one embodiment of the present invention may include the steps of pre-processing and crushing herbaceous biomass and supplying it to a hydroextruder; supplying the hydroextruded biomass crushed in the hydroextruder to a disk refiner; and physically processing the biomass hydroextruded biomass by controlling the solid-liquid ratio of the disk refiner.

[0031] Usable herbaceous biomass may be one or more selected from, but is not limited to, hemp, sorghum, jute, sweet sorghum bagasse, giant reed, and EFB.

[0032] It is desirable to first perform a preprocessing grinding process on herbaceous biomass before the hydroextrusion process. The herbaceous biomass is preprocessed and ground to an average size of 1 to 10 mm using a cutting mill, and then fed to the hydroextruder.

[0033] The temperature of the water injected for hydrolysis and pulverization of the pretreated pulverized biomass may be 100°C or lower, for example, in the range from room temperature to 100°C. However, since the crystallinity of the fibrous biomass according to the temperature of the injected water in the hydrolysis and pulverization process was not large, the temperature range is not particularly limited.

[0034] Additionally, the rate at which biomass is injected into the hydro extruder can range from 5 kg / h to 20 kg / h, but the injection rate can be adjusted depending on the equipment and purpose used and is not limited thereto.

[0035] The hydro-pulverizing extruder that can be used in the present invention can be either a twin-screw extruder or a disc-type crusher. Among these, the use of a twin-screw extruder comprising a front screw, a kneading block, and a rear screw can enhance the fiber pretreatment effect. The screw speed of a twin-screw extruder for hydro-pulverizing hemp or fennel can range from 150 rpm to 200 rpm, but is not limited thereto.

[0036] The present invention is characterized by performing a physical treatment process, i.e., a refining process, after the hydro-pulverization process of biomass. By adjusting the solid-liquid ratio of the disc refiner, fibrous biomass with a desired aspect ratio and crystallinity can be obtained. Experimental results confirmed that a solid-liquid ratio of 1:7 to 1:10 is preferable for obtaining fibrous biomass with a strength suitable for use as a reinforcing material in biodegradable resin compositions.

[0037] According to the manufacturing method including a physical treatment process according to the present invention, a fibrous biomass having an aspect ratio in the range of 3.5 to 6.0, an average particle thickness in the range of 10 to 25 ㎛, a particle distribution in the range of 1 to 3, and a crystallinity in the range of 45% to 60% can be manufactured, which is suitable for use as a reinforcing material of a biodegradable resin composition.

[0038] A biodegradable resin composition according to one embodiment of the present invention may include 20 to 40 wt% of fibrous biomass obtained through the above physical treatment process and 60 to 80 wt% of biodegradable resin.

[0039] Usable biodegradable resins may be selected from the group consisting of, but are not limited to, one or more of polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polycaprolactone (PCL), polyglycolic acid (PGA), polyhydroxyalkanoate (PHA), polyhydroxy butyrate (PHB), copolymers thereof, and mixtures thereof.

[0040] As a specific example, 30% of the biodegradable resin can be replaced with a fibrous biomass pretreated through a physical treatment process and manufactured by blending it with polylactic acid. According to an example, the molded product manufactured using the biodegradable resin composition was confirmed to have excellent mechanical properties, with a tensile strength in the range of 75 to 85 MPa, a flexural strength in the range of 106 to 120 MPa, and an impact strength in the range of 20 to 30 J / m.

[0041] The present invention will be described in more detail below with reference to examples; however, the examples are provided by way of example to help understanding the present invention and should not be construed as limiting the scope of the present invention.

[0042] <Example 1>

[0043] As biomass raw materials, natural fibers such as hemp and ramie (under the red line) were used.

[0044] The biomass hydrolysis and pulverization process used a twin-extruder (TEK40MHS, SM Platech). A mixing zone with kneading blocks and forward screws arranged in an alternating manner was installed to mix the raw materials and feed water, followed by nine backward screws for hydrolysis and pulverization.

[0045] During hydrolysis and crushing using a twin-screw extruder (TEK40MHS, SM Platech), the injection water temperature was varied at a solid-liquid ratio (1:15) and sample injection speed (10 kg / h) with different injection water temperatures (25℃, 50℃, 80℃).

[0046] <Example 2>

[0047] The hydration grinding process was performed in the same manner as in Example 1, except that the injection temperature was set to 50°C.

[0048] <Example 3>

[0049] The hydration grinding process was performed in the same manner as in Example 1, except that the injection temperature was set to 80°C.

[0050] <Comparative Examples 1, 3>

[0051] The relative crystallinity of the dry-ground (ground with a cutting mill of 0.5 mm or less) samples was measured without performing the hydro-grinding process of Example 1 using hemp and ramie, respectively, and is shown in Table 1 below.

[0052] <Physical property evaluation>

[0053] The crystallinity of the manufactured biomass fiber reinforcing materials manufactured in the above examples and comparative examples was measured using XRD.

[0054] Sample injection water temperature (℃)I AM (2θ / Intensity)I 200 (2θ / Intensity) Crystallinity(%) Commercial MCC (Avicel PH-101)---77.9 Comparative Example 1-18.4 / 310622.6 / 576946.2 Example 1 RT 18.9 / 297722.2 / 612351.4 Example 250℃ 18.2 / 297322.4 / 625552.5 Example 380℃ 18.2 / 271222.3 / 556851.3

[0055] XRD results showed that cellulose characteristic peaks were observed around 15°, 22°, and 34° in the hemp pith, and the crystallinity was calculated to be higher in hydrated grinding than in dry grinding. In addition, it appears that the crystallinity of the hemp pith increased due to the separation of amorphous components by hydrated grinding, and no significant change in crystallinity was observed with an increase in hydrated grinding temperature beyond a certain level.

[0056] <Examples 4 and 8>

[0057] 1) Hydrolysis crushing process

[0058] As biomass raw materials, natural fibers such as hemp and ramie (under the red line) were used.

[0059] The hemp core and hemp were pre-processed and crushed to a size of 2 mm using a cutting mill.

[0060] The biomass hydrolysis and pulverization process used a twin-extruder (TEK40MHS, SM Platech). A mixing zone with alternating kneading blocks and forward screws was installed to mix the pre-pulverized biomass raw material with the feed water. Subsequently, nine backward screws, identified as optimal in previous research, were arranged to perform hydrolysis and pulverization.

[0061] The pretreatment crushing (2 mm), solid-liquid ratio (1:20), screw speed (180 rpm), sample injection speed (8 kg / h), and hydration crushing solid-liquid ratio (1:1.2) were performed using a twin-screw extruder (TEK40MHS, SM Platech) at an injection water temperature of 50°C.

[0062] 2) Physical treatment (refining) process

[0063] A slurry was prepared using a solvent (water) from hemp pith fibers produced through a hydrolysis grinding process. A physical refining process was performed using a disc refiner with a solid-liquid ratio of 1:10. The optimal conditions for the physically treated hemp pith fibers were determined through particle size analysis.

[0064] <Example 5>

[0065] The hydropulverization process and physical refining process were performed in the same manner as in Example 4, except that the high-liquid ratio of the disk refiner was set to 1:9.

[0066] <Example 6>

[0067] The hydropulverization process and physical refining process were performed in the same manner as in Example 4, except that the high-liquid ratio of the disk refiner was set to 1:8.

[0068] Comparative Example 2

[0069] Only the hydrolysis crushing process was performed without performing the refining process using hemp pulp.

[0070] <Physical property evaluation>

[0071] The particle distribution, aspect ratio, and average thickness of the biomass fiber reinforcing materials manufactured in the above examples and comparative examples were measured, and the results are shown in Table 2 below.

[0072] Sample High-Liquidity Particle Distribution (SPAN) Aspect Ratio (L / D) Average Thickness (㎛) Commercial MCC (Avicel, PH-101) -1.8 (0.0) 4.7 (1.0) 13 Comparative Example 1 - 2.3 (0.1) 3.9 (0.0) 53 Comparative Example 2 - 2.7 (0.1) 4.5 (0.0) 29 Example 4 1: 10 2.9 (0.1) 4.5 (0.1) 29 Example 5 1: 9 2.8 (0.0) 4.8 (0.0) 20 Example 6 1: 8 2.9 (0.0) 4.9 (0.0) 17

[0073] From the above results, the particle size distribution according to the high-liquid ratio showed a change in particle size, unlike the particle size distribution according to the gap size. As the high-liquid ratio decreased, the number of fibers with large particle sizes decreased and the number of fine fibers increased. In addition, as the high-liquid ratio decreased from 1:10 to 1:8, the particle size of D50 decreased from 69 ㎛ to 43 ㎛ and the aspect ratio increased from 4.5 to 4.9. Accordingly, the average thickness calculated from D50 and the aspect ratio also decreased from 29 ㎛ to 17 ㎛. Since high-concentration slurry causes problems such as clogging when continuously injected into a disc mill, a high-liquid ratio of 1:8 was determined to be the limit for smooth injection of the hydrated pulverized product. Therefore, the final conditions for the physical treatment of hemp pith fibers were selected as a gap size of 0.001 inch and a high-liquid ratio of 1:8.

[0074] <Examples 7 and 9>

[0075] The particle distribution, aspect ratio, average thickness, and crystallinity of each hemp core and yangma (bottom of red stem) were evaluated and described by applying the hydrolysis grinding and physical refining treatment conditions confirmed in the above examples.

[0076] Sample particle distribution (SPAN) aspect ratio (L / D) average thickness (㎛) crystallinity (%) PLA (4032D)----commercial MCC (Avicel PH-101) 1.84.71377.9 hemp 12.33.95353.1 Example 4 (hydration grinding) 2.74.72453.2 Example 7 (physical treatment) 2.94.91752.6 yangma (Hongdae bottom) comparative example 31.84.09248.7 Example 8 (hydration grinding) 2.44.61848.9 Example 9 (physical treatment) 2.44.71547.1

[0077] The particle size analysis results showed that the average particle size and thickness of the safflower pith were larger and the aspect ratio was smaller than that of the hemp pith when dry-milled, but after the milling and fiberization processes, the average particle size and thickness were smaller and the aspect ratio was similar to that of the hemp pith. The crystallinity and composition of the safflower pith produced through the same hydro-milling and physical treatment processes as the hemp pith were observed and compared with those of the hemp pith.

[0078] As a result of crystallinity analysis, the crystallinity of the safflower core was lower than that of the hemp core. This is thought to be due to the lower glucan content of the safflower core than that of the hemp core, as shown in the composition analysis. In order to confirm the influence of the property reinforcing effect according to the crystallinity and composition, the properties of the composite with 30 wt% replacement were evaluated.

[0079] According to a comparative example, hemp core and sphagnum moss (bottom of Hongdae) that were not subjected to a physical refining process, and hemp core samples and sphagnum moss (bottom of Hongdae) that underwent the treatment process according to Examples 6 to 9 were mixed with polylactic acid (PLA), a biodegradable resin, to prepare a biodegradable resin composition. 30 wt% of the PLA in the biodegradable resin was replaced with the fibrous biomass according to the examples and comparative examples. The evaluation results are shown in Table 4 below.

[0080] Sample replacement rate (wt%) Tensile strength (MPa) Flexural strength (MPa) Impact strength (J / m) PLA (4032D) -73.0±1.9 1 12±3.7 2 2.8±3.9 Commercial MCC (Avicel PH-101) 3 058.8±3.0 8 3.4±1.7 2 1.5±1.2 Hemp Comparative Example 3 076.4±1.1 1 04.7±3.2 2 4.9±1.6 Example 4 (Hydrated crushing) 3 082.9±1.2 1 05.8±5.5 2 2.3±2.2 Example 7 (Physical treatment) 3 082.6±1.3 1 05.0±4.9 2 1.8±2.2 Hemp (Hongdae bottom) Comparative Example 33066.6±7.094.4±5.622.0±1.1Example 8 (hydration grinding)3078.3±2.6107.4±5.423.8±2.4Example 9 (physical treatment)3078.4±3.1108.0±5.520.0±1.0

[0081] As a result of the above property evaluation, the tensile strength of the fiber composite tended to increase in the case of hydro-grinding and physical treatment compared to dry grinding of the yangsang pith, and since the properties of the yangsang pith after hydro-grinding are not significantly different from those of the hemp pith, it was found that it can be sufficiently used as a substitute for the hemp pith in the future.

[0082] From these results, it was confirmed that the filaments of hemp and ramie, including hemp, have sufficient potential to be utilized as natural fibers for composites to replace biodegradable plastics.

Claims

1. A step of preprocessing and crushing herbaceous biomass and supplying it to a hydroextruder; A step of supplying the hydrolyzed biomass extrudate from the hydrolyzed extruder to a disk refiner; and A method for producing fibrous biomass, comprising a step of physically treating the biomass hydrated extrudate by controlling the solid-liquid ratio of the disc refiner.

2. In paragraph 1, A method for producing fibrous biomass, wherein the above herbaceous biomass is at least one selected from hemp, kenaf, jute, sweet corn bagasse, giant reed, and EFB.

3. In paragraph 1, The above pretreatment crushing is a method for producing fibrous biomass, wherein the herbaceous biomass is crushed into pieces having an average size of 1 mm to 10 mm using a cutting mill.

4. In paragraph 1, A method for producing fibrous biomass, wherein the above-mentioned hydroextruder is a twin-extruder including a front screw, a kneading block, and a rear screw.

5. In paragraph 4, A method for producing fibrous biomass, wherein the screw speed of the above twin-screw extruder is in the range of 150 rpm to 200 rpm.

6. In paragraph 1, A method for producing fibrous biomass wherein the above high-efficiency ratio is in the range of 1:7 to 1:

10.

7. In paragraph 1, A method for producing fibrous biomass, wherein the aspect ratio of the fibrous biomass is in the range of 3.5 to 6.0 and the average particle thickness is in the range of 10 to 25 ㎛.

8. In paragraph 1, A method for producing fibrous biomass, wherein the particle distribution of the fibrous biomass is in the range of 1 to 3 and the crystallinity is in the range of 45% to 60%.

9. A biodegradable resin composition comprising 20 to 40 wt% of the fibrous biomass manufactured according to paragraph 1 and 60 to 80 wt% of a biodegradable resin.

10. In paragraph 9, A biodegradable resin composition having a tensile strength of 75 to 85 MPa, a flexural strength of 106 to 120 MPa, and an impact strength of 20 to 30 J / m, manufactured using the biodegradable resin composition.