Polymer composite comprising biomass, and method for producing same

Abstract

The present invention relates to a polymer composite comprising biomass, and a method for producing same, and, more specifically, to: a method for producing a polymer composite comprising Chlorella-derived biomass, the method comprising a saccharification step of performing acid-catalyzed saccharification on Chlorella biomass in the presence of an acid, a step of mixing the saccharification solution, obtained in the saccharification step, and calcium hydroxide so as to neutralize same, a step of recovering, from the neutralization product obtained in the neutralization step, a solid part containing a precipitated salt, and a step of mixing the solid part and a polymer so as to prepare a polymer mixture; and the polymer composite composite, which comprises: the solid part of a neutralized saccharification solution obtained after acid-catalyzed saccharification of Chlorella biomass and neutralization; and a polymer.

Description

Polymer composite containing biomass and method for producing the same

[0001] The present invention relates to a polymer composite containing biomass and a method for producing the same, and more particularly, to a polymer composite derived from chlorella biomass and a method for producing the same.

[0002] With the recent advancement of eco-friendly technologies, the development and application of new biomaterials from agricultural byproducts and wastes has emerged as a major task.

[0003] Meanwhile, Chlorella (Chlorophyta, Trebouxiophyceae) is one of the most extensively studied microalgae, with over 70 companies conducting commercial-scale cultivation worldwide, and Chlorella biomass has been used for a variety of purposes, including as a dietary supplement and as a feedstock for ethanol production, but research on its use in the development of bioplastics and thermoplastic composites is insufficient.

[0004] Most of them have focused on utilizing the entire algal biomass rather than defatted residual algal biomass as an additive to conventional composites in the food packaging field, while another approach is to use defatted Chlorella biomass (DCB) as an additive to polymer resins with the aim of reducing material costs and simultaneously improving the performance of the resulting composites.

[0005] For example, Korean Patent No. 10-2455102 relates to a biodegradable material based on defatted Chlorella biomass and a method for producing the same, and relates to the use of defatted Chlorella biomass (DCB) as an additive for the purpose of reducing material costs and simultaneously improving the performance of the resulting composite material.

[0006] However, in addition to the aforementioned Korean Patent No. 10-2455102, there remains a need to improve the physical and functional properties of polymer composites containing biomass, and thus, development of composites that enhance the mechanical strength and physical properties of plastics and also improve biodegradability and economic efficiency is required.

[0007] Accordingly, one aspect of the present invention provides a method for producing a polymer composite including a new biomass final material obtained through an additional processing step for adding value to chlorella biomass, for example, defatted chlorella biomass (DCB).

[0008] Another aspect of the present invention is to provide a polymer composite comprising a novel biomass final material obtained in a high value-added process targeting chlorella biomass, for example, defatted chlorella biomass (DCB).

[0009] According to one aspect of the present invention, a method for producing a polymer composite including chlorella-derived biomass is provided, the method comprising: a saccharification step of acid-catalyzed saccharification of chlorella biomass, for example, chlorella defatted residue biomass, in the presence of an acid; a neutralization step by mixing the saccharified liquid obtained by the saccharification step with calcium hydroxide; a step of recovering a solid containing a precipitated salt from the neutralization result obtained in the neutralization step; and a step of mixing the solid with a polymer to prepare a polymer mixture.

[0010] According to another aspect of the present invention, a polymer composite is provided, which comprises a neutralized saccharified liquid solid obtained by the manufacturing method of the present invention and obtained after saccharification and neutralization under acid conditions of chlorella biomass, for example, chlorella defatted residue biomass; and a polymer.

[0011] The plastic material provided by the present invention, which utilizes the final residue containing precipitates during the saccharification process of chlorella biomass, for example, defatted chlorella biomass, has excellent mechanical properties such as elongation at break and tensile strength.

[0012] Figure 1 shows a photograph of a sample (b) obtained by treating delipidated chlorella biomass (DCB) (a) recovered after lipid extraction (interchangeably used with 'residue biomass') at high temperature (121°C, 15 minutes) and neutralizing it in a solution containing sulfuric acid, i.e., the final residual biomass (RDCB) of the present invention, in its solid content.

[0013] Figure 2 shows the results of quantitative analysis of monosaccharides eluted in the liquid phase of the sample of Figure 1(b), i.e., the neutralized product, during the saccharification process depending on the concentration of sulfuric acid.

[0014] Figure 3 shows the results of comparing the mechanical properties of plastic composites containing 20 wt% of conventional residual biomass (DCB) or final residual biomass (RDCB) of the present invention.

[0015] Figure 4 shows FE-SEM electron micrographs of various plastic composites containing final residue biomass (RDCB).

[0016] Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings. However, the embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0017] According to the present invention, a method for producing a polymer composite having improved physical properties is provided by mixing a polymer with the neutralized product of a saccharified liquid produced by acid-catalyzed conversion of residual chlorella biomass from which lipids have been removed.

[0018] The method for producing a polymer composite of the present invention comprises a saccharification step of acid-catalyzed saccharification of chlorella biomass, for example, chlorella defatted residue biomass, in the presence of an acid; a neutralization step of mixing the saccharified liquid obtained by the saccharification step with calcium hydroxide; a step of recovering a solid containing a precipitated salt from the neutralization result obtained in the neutralization step; and a step of mixing the solid with a polymer to prepare a polymer mixture.

[0019] The chlorella biomass used in the present invention, for example, chlorella defatted residual biomass, refers to a residual chlorella biomass from which lipids have been removed, obtained through solvent extraction of chlorella. More specifically, a biomass from which lipids have been removed (defatted) can be obtained in the process of recovering useful materials such as fatty acids and carotenoids pigments through solvent extraction of chlorella produced through fermentation or photoculture. The method for obtaining such chlorella defatted residual biomass is not particularly limited, and may be obtained by a known method disclosed in, for example, Korean Patent No. 10-2455102.

[0020] The above saccharification step is a step of acid-catalyzed saccharification of chlorella biomass, for example, chlorella defatted residue biomass, in the presence of an acid, and the acid of the saccharification step may be sulfuric acid, hydrochloric acid or phosphoric acid, which may be treated to be present at a concentration of 0.5 to 1 N, and sulfuric acid may be preferably used.

[0021] The above saccharification step may involve heating, and more specifically may be performed by heating at a temperature of 100 to 180°C for 1 to 60 minutes, for example, by heating at a temperature of 110 to 130°C for 5 to 30 minutes.

[0022] Furthermore, a neutralization step is performed by mixing the acidic saccharification solution obtained by the saccharification step with calcium hydroxide, and the neutralization step may be performed by mixing calcium hydroxide so that the pH becomes 7 to 8.0, and for example, it may be performed so that the pH becomes 7.1 to 7.3.

[0023] Subsequently, a step of recovering a solid containing a precipitated salt from the neutralization result obtained by the neutralization step is performed, and further, a step of preparing a polymer mixture by mixing the solid and a polymer is performed.

[0024] For example, when sulfuric acid is used as an acid catalyst, sulfate (SO4) derived from the sulfuric acid catalyst 2- ) is neutralized using calcium hydroxide (Ca(OH)2) to form a salt containing calcium sulfate (CaSO4), and when the final residue, which is a solid containing the resulting precipitated salt, is used to manufacture a plastic composite, the physical properties of the composite can be improved.

[0025] Meanwhile, the step of recovering the solid may be performed including a solid-liquid separation step; and a drying step of the separated solid, wherein the solid-liquid separation may be performed by centrifugation, natural sedimentation, or membrane filtration, and the drying step may be performed by freeze-drying or drying at a temperature of 20 to 100°C, and for example, the drying may be performed by oven drying at a temperature of 50 to 80°C.

[0026] The polymer included in the polymer composite of the present invention may be a thermoplastic polymer, and may be at least one selected from the group consisting of, for example, biodegradable polymers and ethylene-vinyl acetate copolymers (EVA), and may also be at least one selected from the group consisting of ethylene-vinyl acetate copolymers (EVA), polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), poly(butylene adipate)-based block copolymers, poly(butylene succinate) (PBS), polyhydroxyalkanoate (PHA)-based block copolymers, and polycaprolactone (PCL), and the poly(butylene adipate)-based block copolymer may be, for example, poly(butylene adipate-co-terephthalate) (Poly(butylene adipate-co-terephthalate, PBAT), poly(butylene adipate-co-glycol), PBAG), poly(butylene adipate-co-lactide), PBAL), poly(butylene adipate-co-caprolactam), PBAC), etc., and polyhydroxyalkanoate (PHA) block copolymers may be poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), PHBHHx), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), Poly(3-hydroxybutyrate-co-lactide), PHBV), PHB-co-LA,Poly(3-hydroxybutyrate-co-ethylene glycol) (PHB-co-EG), etc., and preferably at least one of the biodegradable polymers.

[0027] In the present invention, the step of preparing the polymer mixture may be performed by mixing the solid and the polymer at 80 to 220°C, or 85 to 200°C, for example, 90 to 190°C, but is not limited thereto, and may vary depending on the type of polymer mixed into the polymer mixture, and may be performed in a range from the melting point of the polymer to below the carbonization temperature.

[0028] Meanwhile, the step of preparing the polymer mixture may include a solid content including a precipitated salt in an amount of 1 to 50 wt% based on the total weight of the polymer mixture, for example, 5 to 30 wt%. If the solid content including a precipitated salt is below the above range, the effect of improving the physical properties of the polymer composite may be minimal, and if it exceeds the above range, problems may arise in the color, turbidity, and odor of the cast polymer composite.

[0029] According to another aspect of the present invention, a polymer composite obtained by the above-described manufacturing method of the present invention is provided.

[0030] More specifically, the polymer composite of the present invention is obtained by the method for producing the polymer composite of the present invention, and includes a neutralized saccharified liquid solid obtained after saccharification and neutralization under acid conditions of chlorella biomass, for example, chlorella defatted residue biomass; and a polymer.

[0031] In relation to the polymer composite of the present invention, the term 'neutralized saccharified liquid solids' may be used interchangeably with 'final residual biomass' (RDCB) of the present invention, and all of the above-described matters with respect to the final residual biomass and the polymer may be equally applied.

[0032] The polymer included in the polymer composite of the present invention may be a thermoplastic polymer, and may be, for example, at least one selected from the group consisting of biodegradable polymers and ethylene-vinyl acetate copolymers (EVA), and may also be at least one selected from the group consisting of ethylene-vinyl acetate copolymers (EVA), polybutylene adipate terephthalate (PBAT), and polylactic acid (PLA), and preferably at least one of the biodegradable polymers.

[0033] Meanwhile, the polymer composite may contain a neutralized saccharification liquid solid content, which is a solid content including a precipitated salt, in an amount of 1 to 50 wt% based on the total weight, for example, 5 to 30 wt%. If the solid content including a precipitated salt is below the above range, the effect of improving the physical properties may be minimal, and if it exceeds the above range, problems may occur in the color, turbidity, and odor of the cast composite.

[0034] Hereinafter, the present invention will be described in more detail through specific examples. The following examples are merely illustrative examples to aid understanding of the present invention and are not intended to limit the scope of the present invention.

[0035] Example

[0036] 1. Acid-catalyzed saccharification of delipidated chlorella biomass (DCB) and measurement of monosaccharide content dissolved in the supernatant.

[0037] 100 g of dried defatted Chlorella biomass (DCB) was mixed with 0, 0.25, 0.5, 0.75, and 1.0 N H2SO4 aqueous solutions at a concentration of 100 g / L and heat-treated at 121°C for 15 minutes to perform hydrolysis (saccharification), and the concentration of monosaccharides eluted into the solution was measured by treating with a solution containing sulfuric acid.

[0038] Figure 1 shows a photograph of a sample containing the final residual biomass (RDCB) of the present invention in its solid content, i.e., the product recovered by high-temperature treatment (121°C, 15 minutes) and neutralization of the delipidated chlorella biomass (DCB) (a) (interchangeably used with 'residue biomass') recovered after lipid extraction (b), i.e., the final residual biomass (RDCB) of the present invention.

[0039] Furthermore, for quantitative analysis of monosaccharides eluted into the solution according to the concentration of sulfuric acid treated, experiments were conducted according to the following process.

[0040] Concentrated sulfuric acid stock solution was diluted in distilled water in a 2 L glass bottle to concentrations of 0, 0.1, 0.25, 0.5, 0.75, and 1.0 N, and 1 L of the aqueous solution was added to each bottle. 100 g of dried, defatted chlorella biomass (DCB) was weighed and added to each bottle, followed by hydrolysis (saccharification) in an autoclave at 121°C for 15 min. The recovered saccharified solution was cooled at room temperature for 12 h, and then a portion of the sample was collected from each bottle, centrifuged (×4000 g, 10 min), and 0.22 μm syringe filtered. The monosaccharides eluted in the solution phase were measured using Bio-LC. The measuring equipment used here was a Dionex ICS 5000+ (Sunnyvale, CA, USA) and a CarbonPac SA10-4 μm column.

[0041] As a result of analyzing the monosaccharides eluted from the recovered product through Bio-LC, as can be confirmed in Fig. 2, total monosaccharides were detected at a level of approximately 36 g / L under conditions of a sulfuric acid concentration of 0.5 N or higher, and more than 80 wt% of the total monosaccharides were confirmed to be glucose.

[0042] In the above case, the saccharification efficiency compared to the input defatted chlorella biomass (DCB) is 36 / 100 = 36%, which can be interpreted as corresponding to approximately 36% of the dried residual chlorella biomass being converted into monosaccharides.

[0043] 2. Neutralization of the saccharification solution using calcium hydroxide and recovery of solid and liquid fractions.

[0044] The pH of the recovered solution (saccharification solution) that went through acid catalyst treatment (saccharification step) was around 1.0, and precipitation in the form of CaSO4 salt occurred through neutralization of calcium hydroxide. As a result, it was confirmed that the amount of sulfate remaining in the saccharification solution could be reduced to less than half of the level of the saccharification solution, as shown in Table 1 below.

[0045] Comparison of sulfate concentrations before and after calcium carbonate neutralization of saccharification solution recovered after sulfuric acid treatment. Sulfate (mM) 0.5 N H2SO4 20 9.44 ± 7.30 10.5 N H2SO4-Ca(OH) 2 87.57 ± 2.868

[0046] In more detail, the pH of the recovered solution (saccharification solution) that underwent acid catalyst treatment recovered in the above 1. was around 1.0. After putting this saccharification solution into a 1 L flask, Ca(OH)2 powder (Sigma Aldrich) was added in portions of about 0.1 g while continuously stirring at 400 rpm.

[0047] The pH of the saccharification solution was checked for each input section, and when it reached a pH level of 7.2, neutralization was stopped, and the saccharification solution was centrifuged (×7000 g, 10 minutes) to recover the solid content including residual biomass and precipitated salt, i.e., the final residual biomass (RDCB) of the present invention.

[0048] The solid content recovered after centrifugation in this manner was washed with sterilized distilled water, then centrifuged again (×7000 g, 10 minutes) and dried in an oven at 60°C to obtain dried final residue biomass (RDCB). In this specification, the resultant product (RDCB) is referred to interchangeably as ‘neutralized saccharified liquid solid content’ or ‘final residue biomass’.

[0049] 3. Manufacturing and property evaluation of plastic composites using final residue biomass containing precipitated salts.

[0050] Residual DCB (RDCB) containing precipitated salts was blended with ethylene vinyl acetate copolymer (EVA), polybutylene adipate terephthalate (PBAT), thermoplastic polyurethane (TPU), or polylactic acid (PLA) at 20 wt% each to cast plastic composites.

[0051] In more detail, the oven-dried final residue, i.e., the final residue biomass (RDCB) and DCB (control group) separated and recovered after calcium hydroxide neutralization treatment, were blended with the four remaining polymers (EVA, PBAT, PLA, TPU) at a content of 20 wt% based on the total polymer composite weight.

[0052] Subsequently, polymer composites of each polymer / residue were cast through melt-compounding (Rheocomp 600, MKE), and the rotation speed was 100 rpm for 7 minutes. The mixing temperatures for each polymer were as follows: 90°C (EVA), 135°C (PBAT), and 190°C (PLA and TPU).

[0053] Afterwards, the composite was finally cast in a dog-bone shape using a hot press (CH4386, Carver Inc.), and the hot press operating temperature was applied at the same temperature as the polymer-residue mixing temperature.

[0054] 4. Evaluation of the properties of plastic composites using final residue biomass containing precipitated salts.

[0055] As a result of evaluating the mechanical properties of each polymer composite obtained in the above 3., as can be seen in Fig. 3, when the final residual biomass (RDCB) of the present invention was applied compared to the polymer composite blended with the conventional delipidated biomass (DCB) at the same ratio, the tensile strength and elongation were confirmed to increase in the polymer composite including ethylene vinyl acetate copolymer (EVA), polybutylene adipate terephthalate (PBAT), and polylactic acid (PLA), and were confirmed to decrease somewhat in the polymer composite including thermoplastic polyurethane (TPU).

[0056] Furthermore, particle size observation and mechanical property analysis were performed on each of the above plastic polymer composites using an FE-SEM electron microscope (SUPRA-55VP, Carl Zeiss) and a UTM (Universal Tensile Machine, LF plus of Lloyd instruments).

[0057] For UTM analysis, ASTM D638 type V was followed, and the strain rate was applied as 50 mm / min for EVA, PBAT, and TPU composites and 10 mm / min for PLA composites.

[0058] When the degree of dispersion was qualitatively evaluated through electron microscopy, an additional tendency of increased dispersion was observed in the composite containing RDCB, as can be confirmed in Fig. 4.

[0059] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and it will be apparent to those skilled in the art that various modifications and variations are possible within a scope that does not depart from the technical spirit of the present invention described in the claims.

Claims

1. A saccharification step in which chlorella biomass is subjected to acid-catalyzed saccharification in the presence of acid; A step of neutralizing by mixing the saccharified liquid obtained through the saccharification step with calcium hydroxide; A step of recovering a solid containing precipitated salt from the neutralization result obtained in the neutralization step; and Comprising a step of preparing a polymer mixture by mixing the above solid and polymer, A method for producing a polymer composite comprising chlorella-derived biomass.

2. A method for producing a polymer composite, wherein the saccharification step is performed in the presence of sulfuric acid, hydrochloric acid, or phosphoric acid at a concentration of 0.5 to 1 N.

3. A method for producing a polymer composite according to claim 1, wherein the saccharification step is performed by heating at a temperature of 100 to 180°C for 1 to 60 minutes.

4. A method for producing a polymer composite, wherein the neutralizing step in paragraph 1 is performed by mixing calcium hydroxide so that the pH becomes 7 to 8.

0.

5. In the first paragraph, the step of recovering the solid content is: High-liquid separation stage; and Drying step of separated solids; A method for manufacturing a polymer composite, comprising:

6. A method for producing a polymer composite, wherein the solid-liquid separation in paragraph 5 is performed by centrifugation, natural sedimentation, or membrane filtration.

7. A method for producing a polymer composite, wherein the drying step in paragraph 5 is performed by freeze-drying or drying at a temperature of 20 to 100°C.

8. A method for producing a polymer composite according to claim 1, wherein the polymer is at least one selected from the group consisting of ethylene vinyl acetate copolymer (EVA), polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), poly(butylene adipate) block copolymer, poly(butylene succinate) (PBS), polyhydroxyalkanoate (PHA) block copolymer, and polycaprolactone (PCL).

9. A method for producing a polymer composite, wherein the step of preparing the polymer mixture in the first paragraph is performed by mixing the solid and the polymer at 80 to 220°C.

10. A method for producing a polymer composite, wherein the step of preparing the polymer mixture in the first paragraph includes a solid content including a precipitated salt in an amount of 1 to 50 wt% based on the total weight of the polymer mixture.

11. Obtained by any one of the clauses 1 to 10, A polymer composite comprising a solid content of a neutralized saccharified liquid obtained after saccharification and neutralization treatment under acid conditions of chlorella biomass; and a polymer.

12. A polymer composite material according to claim 11, wherein the polymer is at least one selected from the group consisting of ethylene vinyl acetate copolymer (EVA), polybutylene adipate terephthalate (PBAT), and polylactic acid (PLA).

13. A polymer composite according to claim 11, comprising a neutralized saccharified liquid solid content in an amount of 1 to 50 wt% based on the total weight of the polymer composite.

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