WO2017217677A1 - Method for extracting lignin from biomass, and high-strength environmentally-friendly plastic material comprising lignin obtained thereby - Google Patents

Abstract

The present invention relates to: a method for extracting lignin from biomass; and a high-strength environmentally-friendly plastic material comprising lignin obtained thereby. A plastic composite material using lignin obtained from biomass according to the present invention, which extracts lignin in a high yield from biomass by using a strong acid such as sulfuric acid or hydrochloric acid, can make a so-called lightweight material having remarkably reduced weight compared to that of a conventional plastic composite material comprising a mineral-based filling material such as talc and calcium carbonate. Compared with a simple plastic material, the plastic composite material comprising the lignin produced by the present invention has greatly improved mechanical and chemical properties and the like, and thus can be readily used in an interior material for vehicles, construction, packaging and electronics. In addition, the plastic composite material is an environmentally-friendly material having environmentally-friendly characteristics since the plastic composite material, compared with a conventional petroleum plastic material, emits remarkably less fossil fuel-derived carbon dioxide, which is a greenhouse gas, when incinerated after being disposed. Additionally, the plastic composite material, comprising the lignin, manufactured according to the present invention, is economically advantageous, and thus can be mass-applied and used in various industries such as those of vehicles and construction by replacing a conventional plastic material.

Description

Method for purifying lignin from biomass and high strength environmentally friendly plastic material comprising lignin obtained accordingly

The present invention relates to a method for purifying lignin from biomass and a high-strength, environmentally friendly plastic material comprising lignin obtained according to the present invention, and more specifically, to purifying ligrin from biomass using a strong acid in high yield. It relates to a high strength environmentally friendly plastic material comprising the method and thus obtained lignin.

Recently, due to the serious depletion of energy sources and environmental pollution, there is an urgent need for solutions to alternative energy and environmental pollution problems, and interest in biomaterials that can simultaneously create petroleum resource replacement and greenhouse gas reduction effects is increasing. . Carbon dioxide, which causes severe climate change, has attracted much attention from all over the world, and attention is being paid not only to the industrial sector but also to various fields of society such as energy and economics.

Plastic materials are mostly derived from petroleum-based fossil fuels, and a considerable amount is used for automobile interiors and building interiors. For the purpose of improving the mechanical and chemical properties of plastics, mineral-derived powders, such as talc, are used as fillers. However, such mineral-derived powders such as talc tend to have a higher specific gravity than plastic materials, resulting in an increase in the weight of the plastic material.

Recently, the interest in fuel economy has increased significantly, especially in the automobile industry, and efforts are being actively made to reduce weight while maintaining the same mechanical and chemical properties, particularly for plastics used in automobile interior materials. Lightweight plastic materials can improve fuel efficiency when applied to vehicles, thereby reducing carbon dioxide emissions, which are global warming materials.

These plastic materials emit large amounts of carbon dioxide when incinerated after disposal. Recently, in the automobile industry, construction industry, packaging industry, and electronics industry, attempts have been actively made to suppress carbon dioxide emission, a global warming material derived from plastic materials that are disposed of after use. If incineration produces plastic materials that contain large quantities of materials that do not emit carbon dioxide from fossil fuels and apply them to automobiles, construction, packaging, and electronics industries, the carbon dioxide emissions generated after disposal are significantly reduced. Reduction and consequently contribute to the creation of environmentally friendly plastic materials industry.

Human beings living in the 21st century are facing the challenge of developing fossil fuel alternative resources and researching solar energy, wind power, hydropower, nuclear power, and biomass in order to cope with international environmental regulations such as carbon dioxide emission reduction.

Lignin is typically recovered and commercialized from the Black Liquor wastewater generated in the pulp manufacturing process. Processes for producing pulp are classified according to the pulping agent used, but in recent years, the process for producing kraft pulp has become common. The type of lignin is classified differently depending on the pulp process and the raw material from which it is derived. The types of lignin or lignin derivative products which are by-produced and refined in the pulp process are typically Hardwood Kraft Lignin, Softwood Kraft Lignin, Acetylated Lignin and Lignin Sulfonate. Sulfonate).

Lignin-based materials are used as cement additives, feed additives, phenolic resin raw materials, carbon fiber precursor raw materials, carbon plate precursor raw materials, and manufacturing materials for interior resins. When utilized for such purposes, it is necessary to overcome the inherent brittleness of the lignin material. The brittleness may adversely affect the physical properties of the final product or make it difficult to process to the final product, increase the defective rate of the final product may cause loss in terms of the overall manufacturing process.

For these reasons, many physical and chemical methods for the brittleness of lignin have been developed. Specifically, acetylation, methylation, and hydrogenation methods have been attempted as chemical methods to weaken the hydrogen bond interaction between lignin chains in order to improve the motility of the lignin chains. As a physical method, there is a method of mixing with a flexible polymer type, and as a conventional technique, a method for mixing and applying synthetic polymers such as polyolefin, polyester, and polyethylene oxide (PEO) with various kinds of lignin has been studied. There is a bar. However, in the case of polyolefins such as polypropylene and polyethylene, phase separation in the blend occurs, and it is known that it is almost difficult to use the mixture with lignin. The mixed use of polyethylene oxide resin with lignin is for softening lignin, which lacks the mobility of the chain, and it is necessary to mix a large amount for softening of lignin. Its use is limited. On the other hand, studies on mixing general purpose polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) with lignin have been reported to have no problems due to phase separation.

The prior art uses a method in which lignin and polyester are melted and mixed using a single screw extruder or a twin skew extruder to obtain a processing mixed raw material in which a lignin polymer and a polyester polymer are mixed. However, such high temperature mixing conditions proceed at a condition very close to the temperature at which most lignin is pyrolyzed, so that lignin is chemically decomposed and denatured. The highly hydrophilic lignin contains a large amount of water, and even dried lignin easily absorbs water from the air, thus containing a small amount of water.

In addition, in the case of a polyester chip (powder), the powdered processing is required in order to mix well with the lignin in the powder state before the melting, mixing and processing. In this case it is known that a method of freeze grinding using very inefficient liquid nitrogen is required. Loss of the pulverized polyester sample due to nitrogen vaporized in the above process occurs, and the molecular weight of the polyester is also affected, resulting in a change in lowering the viscosity index. As a result, when mixed with lignin, it becomes more difficult to achieve the original purpose of improving the brittleness of lignin. When lignin and polyester powder are mixed and melt mixed using the extruder described above to produce a uniformly mixed chip, the hydrolysis reaction of the polyester proceeds considerably due to the moisture mixed from the lignin under the processing conditions. . As a result of the depolymerization, the polyester polymer chain is broken and the molecular weight is lowered up to low molecular weight polyester or constituent monomer. These depolymerized low molecular weight materials are considered to be volatile, and are generally considered to be substances to be removed from the lignin and polyester resin mixture. In addition, when a low molecular weight substance is present, the viscosity of the lignin and the polyester resin mixture is lowered, causing a phenomenon of flowing like a low molecular weight liquid, and in this case, it is difficult to process the resin mixture chip. Therefore, in order to produce chips that can be used as raw materials by homogeneously mixing lignin and polyester, the above-mentioned problems of inefficient freeze grinding, water mixing, thermal decomposition of lignin, and depolymerization of polyester by hydrolysis reaction Problems, the production of low molecular weight volatiles, the problem of lowering the viscosity of the mixed melt, etc. have to be solved.

As a conventional technology, for example, [Korean Patent Laid-Open Publication No. 10-2011-0052242] provides a lignin polymer, an environmentally friendly composite for automobile interior using the same, and a manufacturing method thereof. Specifically, lignin and sebacoyl chloride are mixed so that the hydroxyl group and the carboxyl chloride group are 1: 1 to 3 molar ratio, thereby providing an lignin polymer polymerized by ester polymerization at a temperature of 100 to 130 ° C. and a method for preparing the same. When the lignin polymer is produced according to the above-described manufacturing method, it is possible to manufacture composite materials for automobile interior materials that are environmentally friendly and have excellent mechanical properties, but low molecular weight materials are generated during ester polymerization.

Plant cell walls, on the other hand, consist of lignocellulosic material, the structure of which is briefly represented by cellulose (linear glucose polymer), hemicellulose (highly branched heteropolymer) and lignin (crosslinked aromatic polymer).

The combination of polysaccharides (cellulose and hemicellulose) and non-polysaccharide (lignin) components is a major cause of mechanical and biological resistance. Cellulose, the most abundant polysaccharide on earth, is a highly ordered polymer of cellobiose (D-glucopyranosyl-β-1,4-D-glucopyranose), which accounts for more than 50% of the weight of wood.

For cellulose chains that form a long bundle of molecules, microfibrils, wood cellulose has about 10,000 glucose units. The cellulosic material is composed of an amorphous region in which chemical and biochemical reactions are easy and the microfibrils are irregularly arranged, and the microfibrils orderly arranged crystal regions are relatively difficult to react.

Cellulolytic enzymes can hydrolyze cellulose polymers into glucose, the monomer, and the glucose produced is naturally fermented into ethanol by Saccharomyces cerevisiae, a hexasaccharide fermentation yeast. Thus, such biocatalysts (enzymes) are central to biomass ethanol technology.

Hemicellulose is a binding material of cellulose and lignin. Wood hemicellulose is composed of uronic acid as well as glucose, mannose, galactose and arabinose with high content of xylose, short chains (polymerization degree 100 to 200), and highly branched heteropolymers. Hemicelluloses are linked through 1,3, 1,6 and 1,4 glucosidic bonds and are often acetylated.

Lignin is also a three-dimensional polyphenolic structure of 0-2 methoxy group-attached phenylpropanoid units derived from p-hydroxycinamyl alcohol. Lignin is hydrophobic and very resistant to chemical and biological degradation. Lignin structurally surrounds hemicellulose and cellulose fibrils, providing resistance to the biodegradation of these materials and acting as a binder between plant cells as an amorphous material. Non-structural components of plant tissues (phenols, tannins, fats, sterols, sugars, starches, proteins and ashes) generally comprise up to 5% of the dry weight of wood.

In order to produce environmentally friendly plastic materials, many attempts have been made to mix biomass powders that do not emit additional carbon dioxide to existing petroleum plastics such as polypropylene, polyethylene, and PVC. At this time, wood powder, paper powder, cellulose powder, etc. were used as biomass. "Polyolefin-plant fiber-based resin composition (Korean Patent No.0105629)", and "Extruded biodegradable resin composition (Korean Patent No. 10-0443275)" and the like biodegradable plastics, bio-based plastics Eco-friendly plastics are described. However, the mixing of these bimomass powders with plastics has resulted in a significant decrease in mechanical and chemical properties instead of an increase.

Therefore, in the present invention, PLA, starch, modified starch, etc., which leads to a decrease in physical properties while continuing research to achieve the ultimate goal of developing a plastic composite material which can be increased in weight and light weight of the plastic can be achieved Instead of using it, hydrophobic lignin powder is obtained from the biomass using strong acid, and it is used as a filling material of plastic material, which is not only economically advantageous, but also breakthrough lignin plastic which can increase the physical properties of the plastic and achieve weight reduction. The present invention was completed by developing a composite material.

Therefore, the technical problem to be solved in the present invention is to provide a method for purifying lignin from biomass in high yield.

In addition, another technical problem to be solved in the present invention is to provide a method for producing a plastic material using the obtained lignin.

In addition, another technical problem to be solved in the present invention is to provide a high-strength eco-friendly plastic material containing lignin prepared according to the above production method.

In order to solve the above technical problem, the present invention provides a method for purifying lignin from biomass using a strong acid in high yield.

In order to solve the above technical problem, the present invention provides a method for producing a plastic material using the obtained lignin.

In order to solve the above another technical problem, the present invention provides a high-strength eco-friendly plastic material containing lignin prepared according to the manufacturing method.

Plastic composite material using the lignin obtained from the biomass according to the present invention can make a so-called light weight material that is significantly reduced in weight compared to the plastic composite material containing a mineral filler such as conventional talc, calcium carbonate. Plastic composite material containing lignin produced through the present invention as compared to a simple plastic material is greatly improved in mechanical and chemical properties, etc. It is easy to be used in automotive, building, packaging, electronic interior materials. In addition, compared to the existing petroleum-based plastic material, when discarded after incineration, it emits significantly less carbon dioxide derived from fossil fuel, which is a global warming gas. In addition, the plastic composite material including the lignin prepared according to the present invention is economically advantageous and can be applied and used in large quantities in various industries such as automobiles and constructions by replacing the existing plastic material.

The following drawings, which are attached to this specification, illustrate preferred embodiments of the present invention, and together with the contents of the present invention serve to further understand the technical spirit of the present invention, the present invention is limited to the matters described in such drawings. It should not be construed as limited.

1 is a graph showing the measurement of methylation (FT-IR analysis) of lignin according to dimethyl carbonate treatment, where red color represents lignin powder before methylation reaction and black color lignin powder after methylation reaction.

2 is a graph showing the measurement of methylation of lignin (analysis using ₃₁ P-NMR) according to dimethyl carbonate treatment, where red color represents lignin powder before methylation reaction and black color lignin powder after methylation reaction. .

The method for purifying lignin from the biomass of the present invention is characterized by using a strong acid.

As used herein, the term "biomass" is obtained from living or recently dead creatures as a renewable energy source. Biomass is based on carbon, hydrogen and oxygen and can be used directly or converted to other energy products such as biofuels. Biomass energy can be obtained from five energy sources: waste, wood, waste, landfill gas and alcohol fuel. Wood energy harvests wood or uses waste wood.

In the present invention, various lignin-containing biomass such as herbal and wood-based biomass may be used. Compared with herbal biomass, wood-based biomass has a high content of lignin, which is advantageous because a large amount of lignin can be extracted in strong acid. Woody biomass can be used regardless of species such as conifers and hardwoods.

Examples of strong acids used to extract lignin from biomass in the present invention include sulfuric acid, hydrochloric acid, or mixtures thereof, with hydrochloric acid being particularly preferred. On the other hand, weak acids such as acetic acid and succinic acid are not suitable because the efficiency of extracting lignin is quite low.

According to one specific embodiment of the present invention, the method of extracting lignin using a strong acid may consist of the following steps:

(S1) dissolving and dissociating the molecular structure of the biomass containing lignin using a strong acid;

(S2) neutralizing the lignin dissociated in step (S1) with alkali to obtain lignin solid particles; And

(S3) drying and powdering the lignin solid particles obtained in the step (S2).

According to one preferred embodiment of the present invention, step (S1) comprises the steps of: (1) dissolving the molecular structure of the biomass comprising lignin using a high concentration strong acid of at least 70%; And (2) dissociating from the ligrin by hydrolyzing and liquefying the polysaccharide surrounding the lignin using a strong acid at a concentration of 10 to 15% in the biomass in which the molecular structure is dissolved.

(1) is a step of dismantling the molecular structure of the biomass, that is, the crystallization structure. The strong acid used at this time is a high concentrated strong acid of 70% or more, and particularly preferably hydrochloric acid.

In (2), most of the lignin can be extracted as a solid without being dissolved in acid except a small amount of less than 5% of lignin hydrolyzed by acid.

According to one preferred embodiment of the present invention, when using hydrochloric acid as the strong acid in the step (S1), it is preferable to perform hydrolysis at 20 to 40 ℃ for 20 to 40 hours.

According to one preferred embodiment of the present invention, when using sulfuric acid as a strong acid in the step (S1), it is preferable to perform in two steps of (1) and (2), the first hydrolysis is 20 to 40 It is preferably carried out at 1 ° C. for 1 to 6 hours, and secondary hydrolysis at 90 to 115 ° C. for 1 to 3 hours.

Step (S3) is a step of obtaining neutralized form of lignin solid particles by neutralizing the dissociated lignin using an alkali such as NaOH and Ca (OH) ₂ and then washing with wash water. In this case, if the lignin obtained by washing only without neutralization has a considerable acidity, it may cause mechanical and chemical properties to be reduced later when mixed with petroleum-based plastics.

The step (S4) is a step of drying and pulverizing the obtained lignin, dried lignin solid particles obtained at 95 to 105 ℃ and then micronized by a grinder to obtain a lignin powder having an average particle diameter of 1 to 50 ㎛ have. In this case, if the particle size of the lignin powder is 10 μm or less, it may have better mechanical properties, but there is a difficulty in that a significant reduction in yield is accompanied during grinding.

If the surface of the lignin powder obtained according to the present invention is analyzed using an analytical device such as FT-IR, the amount of chemical species such as hydroxyl groups present on the surface can be estimated. Compared with other lignin, lignin extracted with strong acid, especially concentrated sulfuric acid, dehydration condensation effect of sulfuric acid, hydroxyl group, carboxyl group etc. mutually dehydration condensation to form ester group, so the amount of species of hydroxyl group, carboxyl group when analyzed by FT-IR It can be seen that this greatly decreases. This reduction in hydroxyl and carboxyl groups results in increased hydrophobicity of lignin, resulting in more intimate mixing with petroleum-based plastic polymers when subsequently mixed with petroleum-based plastics. This intimate mixing results in an increase in the mechanical properties of the lignin plastic composites.

In order to increase the hydrophobicity of the lignin obtained separately by the strong acid treatment, the hydroxyl group of the lignin can be chemically changed using a silane, a halogenated alkane or the like. However, these treatment methods require highly expensive materials such as silanated materials and halogenated alkanes, and there is a problem of remaining hydrophilic compounds such as methanol and halogenated compounds after the reaction. There is a problem that can lead to degradation. In order to solve this problem, in the present invention, a low-cost and highly reactive dimethylcarbonate is used to further convert the methyl group to a hydroxyl group and a phenolic hydroxyl group to methoxy, thereby maximizing the hydrophobicity of the lignin powder. Present a plan.

According to one preferred embodiment of the present invention, the present invention is characterized by increasing the hydrophobicity of lignin by methylating lignin with dimethylcarbonate.

On the other hand, the present invention provides a method for producing a plastic material using the obtained lignin.

1 to 30% by weight of lignin powder obtained by the strong acid treatment according to the present invention or lignin powder maximized more hydrophobic through dimethyl carbonate treatment, such as thermoplastic resins such as petroleum plastic resins, for example, polypropylene, polyethylene, PVC After mixing with a certain form and cooled to produce a composite plastic product containing the lignin of the desired shape. When the lignin powder is contained in an amount less than 1% by weight, the weight reduction effect due to the lignin powder mixing is insignificant, and it is difficult to expect the improvement of the mechanical properties, particularly the impact strength. On the other hand, when more than 30% by weight of lignin powder is incorporated, the weight reduction effect becomes difficult to fully disperse the lignin powder, which increases, and as a result, there is a high possibility that the decrease in mechanical properties, particularly flexural strength, becomes apparent.

According to one preferred embodiment of the present invention, in the present invention, polypropylene grafted with maleic anhydride group to improve the physical properties of the plastic material of 1 to 10% by weight based on the total weight of the plastic material It is further characterized by the addition of the amount.

On the other hand, the present invention provides a high-strength eco-friendly plastic material containing lignin prepared according to the above production method.

Hereinafter, examples and the like will be described in detail to help understand the present invention. However, embodiments according to the present invention can be modified in many different forms, the scope of the invention should not be construed as limited to the following examples. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

Example 1 Isolation of Lignin from Biomass under Acid Treatment Conditions

Biomass used to extract lignin using strong acid is mixed with pine, fir, lychee pine, oak, acacia and palm empty fruit bunch in equal proportions, and then crushed. The mesh part was selected and used as an acid hydrolysis material.

Volumetric ratio of crushed wood flour and sulfuric acid is 1: 1.5, and 24.0 N sulfuric acid is added, followed by primary hydrolysis for 1 hour at 30 ° C., followed by addition of boiling water corresponding to four times the amount of primary sulfuric acid, at 105 ° C. Secondary hydrolysis was carried out for 1 hour.

In addition, primary hydrolysis was performed using hydrochloric acid as the acid.

After completion of the two-stage hydrolysis with sulfuric acid and one-stage hydrolysis with hydrochloric acid, the reaction mixture was cooled and filtered to collect liquid saccharified liquid, and the remaining lignin as a solid was washed three times or more with alkaline water. Adjusted to 7.0. The washed lignin solids were left to dry for at least 24 hours in a 100 ℃ dryer. Table 1 shows the separation efficiency of lignin using an acid.

Primary hydrolysis acid treatment conditions	Secondary hydrolysis acid treatment condition	Lignin Recovery (%)
24 N sulfuric acid, 30 ° C. 1 hour	6.0 N sulfuric acid, 105 DEG C, 1 hour	90
24 N sulfuric acid, 30 ° C. 1 hour	6.0 N sulfuric acid, 105 DEG C, 2 hours	92
24 N sulfuric acid, 30 ° C. 1 hour	6.0 N sulfuric acid, 105 DEG C, 3 hours	95
24 N sulfuric acid, 30 ° C. 2 hours	6.0 N sulfuric acid, 105 DEG C, 1 hour	80
24 N sulfuric acid, 30 ° C. 4 hours	6.0 N sulfuric acid, 105 DEG C, 1 hour	82
24 N sulfuric acid, 30 ° C. 6 hours	6.0 N sulfuric acid, 105 DEG C, 1 hour	85
20% (w / w) hydrochloric acid, 30 ° C 0.5 hours	-	75
25% (w / w) hydrochloric acid, 30 ° C 0.5 hour	-	80
35% (w / w) hydrochloric acid, 30 ° C 0.5 hours	-	92

As shown in Table 1, in the case of treating sulfuric acid as an acid it can be seen that the lignin recovery rate increases when the first and second hydrolysis treatment for a long time. This is because when the treatment time of sulfuric acid used for hydrolysis is long, it is easy to remove the polysaccharides in the form of a liquid while hydrolyzing the polysaccharides bound to or located in the vicinity of lignin. When hydrochloric acid is treated, there is an advantage in that lignin can be recovered by only one step without the need for two-step hydrolysis. However, compared to sulfuric acid, hydrochloric acid is more corrosive to metals and has difficulty in experiments such as vaporization even at low temperatures. However, when hydrochloric acid is used as a corrosion resistant material, lignin can be recovered with high efficiency as shown in Table 1.

Example 1 Measurement of Hydrophobicity Increase of Lignin According to Dimethylcarbonate Treatment

800 g of micronized lignin powder was dissolved in 15 L of DMSO (dimethyl sulfoxide) solvent. 373 g of caustic soda and DMC (dimethyl carbonate) were added to the DMSO solution with varying amounts. Thereafter, the reaction was performed at 120 ° C. for about 15 hours. After completion of the reaction, the reaction solution was cooled to room temperature and then precipitated by addition of 2N HCl to recover lignin to which the methyl group was transferred. The methylation degree of the recovered lignin was quantified using 31 P NMR. Table 2 shows the degree of methylation of lignin according to the reaction conditions according to the change of DMC input conditions.

DMC Dose (g)	Reaction temperature (℃)	Response time (hrs)	Lignin methylation conversion (%)
103	120	15	20
206	120	15	24
412	120	15	76
1,236	120	15	90
2,472	120	15	92

As can be seen in Table 2 above, increasing the DMC dose increases the methylation conversion of lignin, reaching a conversion rate of 90% or more. Thus, the presence and conversion of phenol-based hydroxyl groups before and after the reaction using the FT-IR apparatus for lignin powder having a conversion rate of 90% or more are shown in FIG. 1.

1 is a graph showing the measurement of methylation (FT-IR analysis) of lignin according to dimethyl carbonate treatment, where red color represents lignin powder before methylation reaction and black color lignin powder after methylation reaction. As shown in FIG. 1, the phenolic hydroxyl group present on the surface of the lignin was methylated according to the dimethyl carbonate treatment, and the peak around wavelength 3,500 nm was significantly reduced. From these results, the hydroxyl group is methylated by the treatment of DMC, and consequently, the hydrophobicity is expected to increase greatly.

2 is a graph showing the measurement of methylation of lignin (analysis using ₃₁ P-NMR) according to dimethyl carbonate treatment, where red color represents lignin powder before methylation reaction and black color lignin powder after methylation reaction. . As shown in FIG. 2, it was confirmed that various types of hydroxyl groups present on the surface of the lignin were methylated according to the dimethyl carbonate treatment, thereby greatly reducing the characteristic peaks corresponding to the hydroxyl groups. These results suggest that the hydroxyl group present in the lignin is methylated by the treatment of DMC, and consequently, the hydrophobicity is greatly increased.

Example 3 Measurement of Hydrophobicity Increase of Lignin According to Treatment of Silane Coupling Compound

Various silane coupling compounds may be used to react with the hydroxyl groups present on the surface of the lignin to cause silanization, resulting in increased hydrophobicity of the lignin. In this experiment, three representative silane coupling compounds (3-aminopropyltriethoxysilane, glycidoxypropyltrimethoxysilane, methylacryloxypropyltrimethoxysilane) were used to modify the surface of lignin. After adding lignin powder to a silane coupling compound solution of a certain concentration, the reaction was performed at 90 ° C. for 12 hours. After filtration, washing and drying, the reacted lignin powder was obtained. The degree of silane reaction of lignin powder was estimated through elemental analysis of Si.

Silane Coupling Compound	Reaction condition	Silane Reaction Conversion Rate (%)
3-aminopropyltriethoxysilane	2% silane coupling compound (w / w)	35
glycidoxypropyltrimethoxysilane	2% silane coupling compound (w / w)	20
methylacryloxypropyltrimethoxysilane	2% silane coupling compound (w / w)	23

As shown in Table 3, the best silane coupling compound was found to be 3-aminopropyltriethoxysilane, but the conversion was less than 35%.

Example 4 Preparation of Petroleum Plastic Resin (Polypropylene) Containing Lignin

After atomizing the lignin powder obtained in Example 1, 5% lignin powder was polypropylene (PP; polypropylene), 1.0 wt% calcium stearate (calcium stearate), 0.5 wt% antioxidant, and titanium oxide (titanium oxide) ) A plastic composition for automobiles was prepared by injection molding the composite resin prepared by adding 5.0 wt%. Table 4 shows the physical properties of the petroleum-based plastic resin according to the lignin powder particle diameter.

Lignin Powder Average Particle Size (㎛)	Tensile Strength (MPa)	Izod impact strength (J / m)	importance
20 or less	40	45	0.98
20-50	38	42	0.98
50-100	36	35	0.99
More than 100	32	30	0.99

As shown in Table 4, the smaller the lignin powder size shows a tendency to increase the physical properties such as tensile strength, impact strength and decrease the specific gravity is suitable for producing excellent lignin-containing composite plastic resin.

Example 5 Preparation of Methylated Hydrophobic Lignin and Petroleum Plastic Resin (Polypropylene) Mixture

After atomizing the methylated hydrophobic lignin powder obtained in Example 2, the 5% lignin powder was polypropylene (PP; polypropylene), 1.0 wt% calcium stearate, 0.5 wt% antioxidant, and titanium oxide (Titanium oxide) 5.0wt% composite resin prepared by injection molding to prepare a plastic composition for automobiles. Table 5 shows the physical properties of the petroleum crab plastic resin according to the particle size of the methylated hydrophobic lignin powder.

Lignin Powder Average Particle Size (㎛)	Tensile Strength (MPa)	Izod impact strength (J / m)	importance
20 or less	50	55	0.97
20-50	42	51	0.97
50-100	40	47	0.98
More than 100	36	42	0.99

As can be seen in Table 5, the smaller the particle size of the methylated hydrophobic lignin powder shows a tendency to increase the physical properties such as tensile strength, impact strength and decrease the specific gravity, which is suitable for producing excellent lignin-containing composite plastic resin.

Example 6 Preparation of Silane-Lignin and Petroleum Plastic Resin (Polypropylene) Mixture by Sealing Coupling

After atomizing the silanated hydrophobic lignin powder using 3-aminopropyltriethoxysilane in Example 3, 5% lignin powder was polypropylene (PP; polypropylene), calcium stearate (1.0 wt%), antioxidant 0.5 wt %, And 5.0 wt% of titanium oxide (titanium oxide) was injected into a composite resin prepared by injection molding a plastic composition for automobiles. Table 6 shows the physical properties of the petroleum-based plastic resin according to the particle size of the lignin powder silanized by the sealing coupling.

Lignin Powder Average Size (㎛)	Tensile Strength (MPa)	Izod impact strength (J / m)	importance
20 or less	41	46	0.98
20-50	39	43	0.98
50-100	36	36	0.99
More than 100	34	31	0.99

As can be seen in Table 6, the smaller the lignin powder size silanized by the sealing coupling shows a tendency to increase and decrease the physical properties such as tensile strength, impact strength is suitable for producing excellent lignin-containing composite plastic resin.

Example 7 Preparation of Petroleum Plastic Resin (Polypropylene) Mixture by Changing the Mixing Amount of Methylated Hydrophobic Lignin

After atomizing the methylated hydrophobic lignin powder obtained in Example 2, varying amounts of lignin powder was polypropylene (PP; polypropylene), 1.0 wt% calcium stearate, 0.5 wt% antioxidant, and oxidation A composite resin prepared by adding 5.0 wt% of titanium oxide was injection molded to prepare a plastic composition for automobiles. Table 7 shows the physical properties of the petroleum-based plastic resin according to the mixing ratio of the methylated hydrophobic lignin powder.

Lignin Blend Rate (%)	Tensile Strength (MPa)	Izod impact strength (J / m)	importance
0	51	53	1.02
5	50	55	0.98
10	47	52	0.95
30	40	43	0.92

As can be seen in Table 7, when the methylated hydrophobic lignin mixing ratio is about 5%, the mechanical properties are increased, and the specific gravity is also greatly reduced. However, it was found that excessive lignin mixing over a certain amount resulted in a decrease in specific gravity, but resulted in a decrease in tensile strength and impact strength.

Example 8 Preparation of Petroleum Plastic Resin (Polyethylene) Mixture Containing Lignin

After atomizing the lignin powder obtained in Example 1, the 5% lignin powder was polyethylene (PE; polyethylene), calcium stearate (1.0 wt%), antioxidant 0.5 wt%, and titanium oxide (titanium oxide) Injection molding a composite resin prepared by adding 5.0wt% to prepare a plastic composition for automobiles. Table 8 shows the physical properties of the petroleum-based plastic resin according to the lignin powder particle diameter.

Lignin Powder Average Particle Size (㎛)	Tensile Strength (MPa)	Izod impact strength (J / m)	importance
20 or less	17	27	0.98
20-50	15	22	0.98
50-100	13	18	0.99
More than 100	11	14	0.99

As shown in Table 8, the smaller the lignin powder size shows a tendency to increase the physical properties such as tensile strength, impact strength and decrease the specific gravity is suitable for producing excellent lignin-containing composite plastic resin.

Example 9 Preparation of Petroleum Plastic Resin (Polyvinyl Chloride) Mixture Containing Lignin

After atomizing the lignin powder obtained in Example 1, the 5% lignin powder was mixed with polyvinylchloride (PVC), 1.0 wt% calcium stearate, 0.5 wt% antioxidant, and titanium oxide (titanium oxide). ) A plastic composition for automobiles was prepared by injection molding the composite resin prepared by adding 5.0 wt%. Table 9 shows the physical properties of the petroleum-based plastic resin according to the lignin powder particle diameter.

Lignin Powder Average Particle Size (㎛)	Tensile Strength (MPa)	Izod impact strength (J / m)	importance
20 or less	25	26	0.98
20-50	21	21	0.98
50-100	18	17	0.99
More than 100	17	13	0.99

As shown in Table 9, the smaller the lignin powder size shows a tendency to increase the physical properties such as tensile strength, impact strength and decrease the specific gravity, which is suitable for producing excellent lignin-containing composite plastic resin.

<Example 10> Preparation of petroleum-based plastic resin (polypropylene) including polypropylene grafted with lignin and maleic anhydride group

After atomizing the lignin powder obtained in Example 1, 5% lignin powder (average particle diameter 20-50 micrometers), maleic anhydride grafted polypropylene grafted with maleic anhydride group, polypropylene (PP; polypropylene), 1.0 wt% of calcium stearate, 0.5 wt% of antioxidant, and 5.0 wt% of titanium oxide (titanium oxide) were injected into a composite resin prepared to prepare an automotive plastic composition. Table 10 shows the physical properties of the petroleum-based plastic resin according to the content of the polypropylene grafted with maleic anhydride group.

Polypropylene grafted with maleic anhydride group (%)	Tensile Strength (MPa)	Izod impact strength (J / m)	importance
0	38	42	0.98
One	49	51	0.98
2	55	56	0.99
10	43	43	0.99

As can be seen in Table 9, when the polypropylene grafted with a maleic anhydride group is added, preferable lignin-containing composite resins such as physical properties such as tensile strength and impact strength are greatly increased and specific gravity is reduced. do. This is presumably due to the formation of a covalent bond between polypropylene and lignin grafted with maleic anhydride group to form a chemical bond that did not exist previously between the interface between lignin and petroleum resin.

Plastic composite material using the lignin obtained from the biomass according to the present invention can make a so-called light weight material that is significantly reduced in weight compared to the plastic composite material containing a mineral filler such as conventional talc, calcium carbonate. Plastic composite material containing lignin produced through the present invention as compared to a simple plastic material is greatly improved in mechanical and chemical properties, etc. It is easy to be used in automotive, building, packaging, electronic interior materials. In addition, compared to the existing petroleum-based plastic material, when discarded after incineration, it emits significantly less carbon dioxide derived from fossil fuel, which is a global warming gas. In addition, the plastic composite material including the lignin prepared according to the present invention is economically advantageous and can be applied and used in large quantities in various industries such as automobiles and constructions by replacing the existing plastic material.

Claims (14)

1. A high yield purification of lignin from biomass using strong acid.
2. The method of claim 1,

   The strong acid is sulfuric acid, hydrochloric acid or a mixture thereof.
3. The method of claim 1,

   A method comprising the following steps:

   (S1) dissolving and dissociating the molecular structure of the biomass containing lignin using a strong acid;

   (S2) neutralizing the lignin dissociated in step (S1) with alkali to obtain lignin solid particles; And

   (S3) drying and powdering the lignin solid particles obtained in the step (S2).
4. The method of claim 3, wherein

   Step (S1) is to (1) dismantle the molecular structure of the biomass containing lignin using a high concentration strong acid of 70% or more; And (2) dissociating from ligrin by hydrolyzing and liquefying the polysaccharide surrounding the lignin using a strong acid at a concentration of 10 to 15% in the biomass in which the molecular structure is decomposed.
5. The method of claim 3, wherein

   If the strong acid in the step (S1) is hydrochloric acid, characterized in that the hydrolysis is carried out for 20 to 40 hours at 20 to 40 ℃.
6. The method of claim 3, wherein

   In the step (S1), when the strong acid is sulfuric acid, the first hydrolysis is performed at 20 to 40 ° C. for 1 to 6 hours, and the second hydrolysis is performed at 90 to 115 ° C. for 1 to 3 hours. Way.
7. The method of claim 3, wherein

   In the step (S3) the alkali is characterized in that NaOH or Ca (OH) ₂ .
8. The method of claim 3, wherein

   The step (S4) is characterized in that for drying the lignin solid particles at 95 to 105 ℃ and then lignin powdered to an average particle diameter of 1 to 50 ㎛.
9. The method of claim 3, wherein

   And methylating lignin using dimethylcarbonate after step (S4).
10. Lignin prepared in a process according to any one of claims 1 to 9.
11. Method for producing a plastic material using the lignin according to claim 10.
12. The method of claim 11,

    The lignin is added in an amount of 1 to 30% by weight based on the total weight of the plastic material.
13. The method of claim 11,

    The polypropylene grafted with maleic anhydride group is further added in an amount of 1 to 10% by weight based on the total weight of the plastic material.
14. Eco-friendly plastic material comprising lignin prepared according to the method according to any one of claims 11 to 13.

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