KR20220046912A - Method of preparing bioplastics comprising lignocellulosic biomass and starch biomass, bioplastics parepared thereby, and film, sheet or container using the same - Google Patents

Abstract

The present invention relates to a method of preparing bioplastics comprising lignocellulosic biomass and starch biomass, which includes: (Step 1) a step of thermo-mechanically mixing or kneading lignocellulosic biomass and starch biomass at a temperature of 100 to 130 ℃ in the presence of a plasticizer to prepare a biomass plasticized composite; (Step 2) a primary low-temperature pulverization step of pulverizing the biomass plasticized composite, polymer, and binder at a high speed of 1000 to 2500 rpm at a temperature of 80 to 150 ℃; (Step 3) a secondary cold pulverization step of pulverizing the primarily low-temperature pulverized powder at a high speed of 1000 to 2500 rpm at a temperature of -20 to 0 ℃; and (Step 4) an extrusion step of supplying the secondarily cold-pulverized powder to a twin-screw extruder having a length-to-diameter ratio (LD ratio) of 60 or more at a constant speed, and extruding steam while discharging the steam generated at a temperature of 130 to 170 ℃ under reduced pressure. According to the present invention, bioplastics can be produced by mixing and compounding the lignocellulosic biomass and starch biomass with polymers without deteriorating the physical properties including strength of the polymer while preventing deterioration due to carbonization and oxidation of the lignocellulosic biomass and starch biomass, so that it is possible to provide an eco-friendly film, sheet or container with excellent physical properties.

Description

Method for producing bioplastic containing lignocellulosic biomass and starch-based biomass, bioplastic produced thereby, and film, sheet or container using the same , SHEET OR CONTAINER USING THE SAME}

The present invention relates to a method for producing a bioplastic containing lignocellulosic biomass and starch-based biomass, a bioplastic produced thereby, and a film, sheet or container using the same.

Bioplastic refers to a polymer plastic manufactured using biomass as a raw material. Bioplastics can be divided into two types: biodegradable plastics with a biomass content of 50 to 70% and biobased plastics with a biomass content of 20 to 25%. It is classified as a bioplastic.

Food packaging, including food, is recognized as one of the final steps for product transportation, delivery, and product information delivery, and its importance has been evaluated relatively low compared to food development and manufacturing, but recently, In addition to functions in the distribution and sales process of food, it is recognized as an important factor for protecting product contents, providing functionality, and securing market competitiveness. As a result, environmental issues are being raised together.

In the 2000s, plastic waste accounted for more than 11% of total waste, and interest and need for methods to efficiently reduce or treat plastic waste have increased. Mixed bioplastics have begun to be studied a lot both at home and abroad, receiving attention as the most eco-friendly and efficient solution.

In order to reduce carbon dioxide, which is recognized as the main culprit of global warming, bioplastic obtained by mixing and compounding plant biomass, a carbon neutral material, with plastic, can be decomposed in a natural state, thereby minimizing environmental impact and environmental pollution. It is useful as a packaging material that not only helps to prevent and solve problems, but also solves food safety problems. Recently, research on the development and commercialization of bioplastics as packaging materials using non-edible organic by-products that are not used for food, excluding the use of starch, which is an existing food resource, in connection with food resources is rapidly progressing.

Recently, bio-based plastics combining or combining biomass and plastics have been developed and mass-produced, and bio-based plastics by the bonding method have improved physical properties such as tensile and elongation compared to existing biodegradable or biodegradable plastics. The final biodegradation period has been extended, so it is being applied to agriculture, food packaging, industry, automobiles, and underground burial.

For example, Patent Document 1 discloses a carbon-neutral biobased plastic containing a biomass plasticization complex made of a plant-derived starch-based biomass and a plant-derived cellulosic biomass, an inorganic filler, and a polymer, Plant-derived starch-based biomass containing 20 wt% or less of cellulose components and plant-derived cellulosic biomass containing 20 wt% or less of starch components thermomechanically at a temperature of 100 to 130 ° C. in the presence of a plasticizer It is disclosed to prepare a thermoplastic biomass composite with improved mechanical properties by kneading or mixing.

However, in the case of bioplastics studied so far, mechanical properties are unstable, and the price is 2-3 times higher than that of conventional plastics, so it is difficult to commercialize them. For example, a disposable plastic container manufactured by using a composition in which starch is added with rice straw, rice husk, and sawdust pulverized material to synthetic resin has been disclosed. However, in the case of such a composition, although it is effective in improving the degradability, when it is produced in the form of a film, there is a disadvantage in that the physical properties of the prepared film, particularly the initial elongation and tensile strength, are inferior.

Patent Document 2 discloses a configuration for manufacturing bioplastic pellets and injecting them by mixing with plastic using non-edible raw materials and titania, zirconia, and silica-based binders left after being used for food.

The bioplastic produced by the method according to Patent Document 2 and the prior art has insufficient strength and thus is not suitable for use as a packaging container for food. In addition, in the above document, problems such as oxidation, carbonization, and phase separation that are essentially occurring when extruding plant material of bioplastics such as lignocellulosic biomass and/or starch-based biomass and means for solving them are disclosed and there is not

Therefore, there was a need for research to develop a new bioplastic manufacturing method capable of minimizing the decrease in the strength of the resulting bioplastic while preventing thermal denaturation of plant raw materials such as lignocellulosic biomass and/or starch-based biomass.

Republic of Korea Patent Publication No. 10-2019-0021961 (published on March 6, 2019) Republic of Korea Patent Publication No. 10-2015-0092949 (published on August 17, 2015)

The present inventors prevent denaturation due to carbonization, oxidation, etc. of plant biomass due to high process temperature in the process of manufacturing bioplastic by mixing and complexing plant material such as lignocellulosic biomass and/or starch-based biomass with plastic It was attempted to develop a method capable of improving or not lowering the physical properties, including strength, of the obtained bioplastic by performing mixing and complexing while doing so.

The problem to be solved by the present invention is not limited to the problem(s) mentioned above, and another problem(s) not mentioned will be clearly understood by those skilled in the art from the following description.

In order to solve the above problems, the present invention provides a method for manufacturing a bioplastic by complexing and extruding a lignocellulosic biomass, a starch-based biomass and a polymer, the method comprising the steps of:

(Step 1) thermomechanically mixing or kneading lignocellulosic biomass and starch-based biomass at a temperature of 100 to 130° C. in the presence of a plasticizer to prepare a biomass plasticization complex;

(Step 2) a first low-temperature grinding step of pulverizing the biomass plasticization composite, polymer, and binder at a temperature of 80 to 150° C. at a high speed of 1000 to 2500 rpm;

(Step 3) a secondary cold pulverization step of pulverizing the first low-temperature pulverized powder at a temperature of -20 to 0° C. at a high speed of 1000 to 2500 rpm; and

(Step 4) An extrusion step of supplying the secondary freeze-pulverized powder to a twin-screw extruder having a length-diameter ratio (LD ratio) of 60 or more at a constant speed, and extruding while discharging water vapor generated at a temperature of 130 to 170° C. under reduced pressure.

According to an embodiment of the present invention, the aforementioned starch-based biomass, corn starch, potato starch, sweet potato starch, cassava starch, oxidized starch thereof, cationic starch, cross-linkage starch, modified starch such as starch ester, or a modified starch thereof starch, which may be selected from combinations; Alternatively, it may be selected from plant seeds, stems, roots, and leaf pulverizing powder, wheat flour, corn flour, rice flour, glutinous rice flour, potato flour, sweet potato flour, cassava flour, or a combination thereof.

According to an embodiment of the present invention, the aforementioned lignocellulosic biomass is, rice husk, soybean hull, wheat hull, jade hull, rice husk, wheat bran, reed, mugwort, bamboo, wood flour, coffee hull, soybean meal, mixtures thereof, or these or selected from the group consisting of pulverized products of wood fibers, cotton fibers, grass fibers, reed fibers, bamboo fibers, modified products thereof, carboxymethyl cellulose, carboxyethyl cellulose, cellulose esters, cellulose ethers, or combinations thereof may be selected from the group. Preferably, rice husk. Soybean hull, wheat husk, jade hull, rice straw, wheat straw, reed. shy. bamboo. wood flour. A pulverized product obtained by pulverizing coffee meal, soybean meal, or a mixture thereof may be used as lignocellulosic biomass.

According to an embodiment of the present invention, the above-mentioned polymer is an olefin-based polymer selected from polypropylene, polyethylene or polystyrene; vinyl-based polymers; amide-based polymers; It may be at least one selected from the group consisting of ester-based polymers, copolymers thereof, mixtures thereof, modified products thereof, and alloys thereof.

According to one embodiment of the present invention, in the above-mentioned step 2, it may be used in an amount of 20 to 50 parts by weight of the biomass plasticized composite, 50 to 80 parts by weight of the polymer, and 1 to 5 parts by weight of the binder.

According to an embodiment of the present invention, in step 2 described above, the binder may be at least one selected from the group consisting of a silane-based coupling agent, a titanium-based coupling agent, and a zirconium-based coupling agent.

In order to solve the above problems, the present invention provides a bioplastic containing lignocellulosic biomass and starch-based biomass produced by the above-described manufacturing method.

In order to solve the above problems, the present invention provides a food packaging container using the bioplastic containing the above-described lignocellulosic biomass and starch-based biomass.

According to the present invention, lignocellulosic and starch-based biomass and polymer are mixed and complexed to prevent denaturation due to carbonization, oxidation, etc. of lignocellulosic and starch-based biomass, and the polymer is mixed and complexed without reducing the physical properties including strength of the polymer. can be manufactured, and an eco-friendly film, sheet or container having excellent physical properties can be provided therefrom.

It should be understood that the effects of the present invention are not limited to the above-described effects, and include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a schematic diagram of a bio-based plastic by a bonding method, the left side is a schematic diagram of biodegradable plastic in which biomass and plastic are mixed, and the right side is a bio-based plastic in which biomass and plastic are chemically bonded or complexed It is a coupling schematic diagram.
2 is a schematic diagram of an ACM (Air Classifying Mill) apparatus generally used for pulverization and classification of lignocellulosic and starch-based plants.
3 is a schematic diagram showing the configuration of the twin screw extruder equipment that can be used in the present invention.
Figure 4 is a schematic diagram showing the configuration of the hopper, kneader, die, etc. of the twin screw extruder that can be used in the present invention.

Before describing the present invention in detail, the terms or words used in this specification should not be construed as being unconditionally limited to their ordinary or dictionary meanings, and in order for the inventor of the present invention to describe his invention in the best way It should be understood that the concepts of various terms can be appropriately defined and used, and furthermore, these terms or words should be interpreted as meanings and concepts consistent with the technical idea of the present invention.

That is, the terms used herein are only used to describe preferred embodiments of the present invention, and are not used for the purpose of specifically limiting the content of the present invention, and these terms represent various possibilities of the present invention. It should be understood that the term has been defined taking into account.

In addition, in the present specification, it should be noted that, unless the context clearly indicates otherwise, the expression in the singular may include a plurality of expressions, and even if it is similarly expressed in plural, it may include the meaning of the singular. do.

When it is stated throughout this specification that a component "includes" another component, it does not exclude any other component, but further includes any other component unless otherwise stated. It could mean that you can.

In addition, in the following, in describing the present invention, a detailed description of a configuration determined that may unnecessarily obscure the gist of the present invention, for example, a detailed description of the known technology including the prior art may be omitted.

Hereinafter, the present invention will be described in more detail.

A first object of the present invention is to provide a method for producing a bioplastic having excellent mechanical properties by complexing a lignocellulosic biomass and a starch-based biomass and then complexing it with a polymer, comprising the steps of:

(Step 1) thermomechanically mixing or kneading lignocellulosic biomass and starch-based biomass at a temperature of 100 to 130° C. in the presence of a plasticizer to prepare a biomass plasticization complex;

(Step 2) a first low-temperature grinding step of pulverizing the biomass plasticization composite, polymer, and binder at a temperature of 80 to 150° C. at a high speed of 1000 to 2500 rpm;

(Step 3) a secondary cold pulverization step of pulverizing the first low-temperature pulverized powder at a temperature of -20 to 0° C. at a high speed of 1000 to 2500 rpm; and

(Step 4) An extrusion step of supplying the secondary freeze-pulverized powder to a twin-screw extruder having a length-diameter ratio (LD ratio) of 60 or more at a constant speed, and extruding while discharging water vapor generated at a temperature of 130 to 170° C. under reduced pressure.

A second object of the present invention is to provide a bioplastic prepared by the above production method and containing lignocellulosic biomass and starch-based biomass.

A third object of the present invention is to provide a film, sheet or container using the bioplastic containing the lignocellulosic biomass and the starch-based biomass, which can be used for packaging food.

In this regard, FIG. 1 shows a schematic diagram of a bio-based plastic by a bonding method, the left side is a mixing schematic diagram of a biomass and a polymer mixed biodegradable plastic, and the right side is a biomass and a polymer chemically bonded or complexed It is a schematic diagram of the bonding of bio-based plastics. The bio-based plastic manufactured according to the present invention not only has a dense mechanical bond, but also exhibits excellent physical properties because the biomass and the polymer are chemically bonded or complexed, as shown in the figure on the right of FIG. 2 .

1. Wood-based biomass and starch-based biomass

In general, plant biomass is largely edible plant (eg, rice flour, soybean flour, corn starch, potato starch, wheat flour, etc.) and non-edible plant (eg, rice husk, soybean hull, wheat hull, jade hull, rice bran, wheat straw, reed) It is divided into ssukdae, bamboo, wood flour, coffee meal, soybean meal, etc.).

Edible plants, such as soybean flour and starch, have uniform quality compared to non-edible plants and are more advantageous for mixing or bonding with polymers or high molecular compounds. However, since edible plants are valuable food resources in some countries and regions, the development and use of bioplastics using non-edible plants has recently been recommended.

An object of the present invention is to use both the above-described edible plants (ie, starch-based biomass) and non-edible plants (ie, woody plants).

The above-mentioned starch-based biomass, corn starch, potato starch, sweet potato starch, cassava starch, oxidized starch thereof, cationic starch, crosslinked starch, starch ester, such as modified starch or a combination thereof; Or a powder obtained by pulverizing plant seeds, stems, roots, and leaves, for example, wheat flour, corn flour, rice flour, glutinous rice flour, potato flour, sweet potato flour, cassava flour, or a combination thereof. can

The above-mentioned lignocellulosic biomass is selected from the group consisting of rice husk, soybean hull, wheat hull, jade hull, rice bran, wheat bran, reed, mugwort, bamboo, wood flour, coffee meal, soybean meal, mixtures thereof, or pulverized products thereof, It may be selected from the group consisting of wood fibers, cotton fibers, grass fibers, reed fibers, bamboo fibers, modified products thereof, carboxymethyl cellulose, carboxyethyl cellulose, cellulose esters, cellulose ethers, or combinations thereof. Preferably, rice husk. Soybean hull, wheat husk, jade hull, rice straw, wheat straw, reed. shy. bamboo. wood flour. A pulverized product obtained by pulverizing coffee meal, soybean meal, or a mixture thereof may be used as lignocellulosic biomass.

2. Plasticizer

The plasticizer or plasticizer usable in the present invention is a polyhydric alcohol having 2 to 22 carbon atoms, particularly a polyhydric alcohol having 2 to 6 carbon atoms, preferably a polyhydric alcohol having 1 to 20 hydroxyl groups, ethers thereof, thioethers, organic It may include esters and inorganic esters, and specifically, ethylene glycol, propylene glycol, glycerin, 1,4-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5 -Pentanediol, 1,5-hexanediol, 1,6-hexanediol, 1,2,6-hexanetriol, 1,3,5-hexanetriol, neopentyl glycol, sorbitol acetate, sorbitol diacetate, sorbitol Monoethoxylate, sorbitol diethoxylate, sorbitol hexaethoxylate, sorbitol dipropoxylate, aminosorbitol, trihydroxymethylaminomethane, glucose/PEG, reaction product of ethylene oxide and glucose, trimethylolpropane monoethoxyl Late, mannitol monoacetate, mannitol monoethoxylate, butyl glucoside, glucose monoethoxylate, α-methyl glucoside, sodium salt of carboxymethyl sorbitol, polyglycerol monoethoxylate, erythritol, pentaerythritol, arabitol , adonitol, xylitol, mannitol, iditol, galactitol, allitol, sorbitol, polyhydric alcohols, esters of glycerin, formamide, N-methylformamide, DMSO, mono- and di-glycerides, alkylamides , polyol, trimethylolpropane, polyvinyl alcohol having 3 to 20 repeating units, polyglycerol having 2 to 10 repeating units, and derivatives thereof.

The interfacial adhesion strengthening agent that can be used in the present invention means a material capable of strengthening a physical or chemical bond between interfaces, for example, PCL (polycaprolactone) or a silane-based crosslinking agent may be mentioned.

3. Polymer

In the present invention, polymer means a polymer or high molecular compound used in a general sense, regardless of the shape of vinyl, film, sheet, container, packaging material, injection product, extruded product, etc., used for living, industrial, agricultural and fishing purposes It may be a polymer or a high molecular compound.

As the polymer that can be used in the present invention, for example, an olefin-based polymer, a vinyl-based polymer, an amide-based polymer, an ester-based polymer, a copolymer thereof, a mixture thereof, a modified product thereof, and an alloy thereof may be mentioned. , specifically, olefin polymers such as polyethylene (PE), polypropylene (PP), polyacetylene (PAc), and polyisobutylene; Polyvinyl chloride (PVC), polyvinyl fluoride (PVF), polyvinyl acetate (PVAc), polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyacrylamide (PAAm), polyacrylonitrile (PAN), vinyl polymers such as polystyrene (PS), polyvinylpyrrolidone (PVP), and polyacrylate; amide polymers such as nylon-6,6 and polycaprolactam (nylon-6); Ester-based polymers such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), mixtures thereof, copolymers thereof, modified products thereof, alloys thereof, and the like can be mentioned. Preferably, mention may be made of thermoplastic polymers such as styrene-based, PVC-based, olefin-based, polyester-based, polyamide-based and urethane-based polymers.

Polymers not mentioned otherwise can be applied to the method according to the present invention if they can produce eco-friendly bio-based plastics, and it is natural that they can fall within the scope of the present invention.

4. binder

In the present invention, the binder refers to a material that enables the formation of a complex by physically and/or chemically bonding or connecting the biomass plasticization complex and the polymer or high molecular compound, for example, a silane-based coupling agent, titanium-based It may be selected from the group consisting of a coupling agent and a zirconium-based coupling agent. Such a binder may be used in an amount of 0.5 to 6 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the total of the biomass plasticization complex and the polymer or high molecular compound.

5. Additives

The bioplastic according to the present invention may further include additives such as a lubricant such as calcium stearate, an antibacterial agent such as zinc oxide, a coating agent such as modified starch, PE wax, and a filler such as talc, if necessary.

The lubricant is a substance that assists in mixing the hydrophilic plant powder into the hydrophobic polymer or high molecular compound due to the surface hydroxyl group, and includes a hydrophobic part (eg alkyl chain) and a hydrophilic part (eg amine) in one compound. salts, lead sulfate, sulfonates, and carboxylates) together.

Long-chain fatty acid salts, such as stearate compounds, specifically calcium stearate, zinc stearate, and the like, can be mentioned as compounds having both a hydrophobic moiety (eg an alkyl chain) and a hydrophilic moiety (eg a salt). These lubricants are not strictly limited, but may be used in an amount of 0.5 to 5 parts by weight, preferably 1 to 3 parts by weight, more preferably 1.5 to 2.5 parts by weight based on 100 parts by weight of the total of the plant and the polymer or high molecular compound. there is.

The antibacterial agent is a substance that imparts antibacterial functionality to the bioplastic, and for example, zinc oxide and the like may be mentioned. These antibacterial agents are not strictly limited, but may be used in an amount of 0.5 to 5 parts by weight, preferably 1 to 3 parts by weight, more preferably 1.5 to 2.5 parts by weight based on 100 parts by weight of the total amount of the plant and the polymer or high molecular compound. there is.

Modified starch refers to starch modified to exhibit different functions or properties by chemically modifying starch-based biomass, and is added to aid in mixing of plant biomass powder and polymer powder. The modified starch may be used in an amount of 0.1 to 10 parts by weight or less, preferably 0.5 to 8 parts by weight, more preferably 1 to 5 parts by weight based on 100 parts by weight of the total amount of lignocellulosic and starch-based biomass and polymer. If it is added in excess of the above range, the biomass and the polymer matrix are mixed too tightly, making it difficult to move the raw material, and if it is added too little, the mixing aid effect between the biomass plasticized composite powder and the polymer matrix is not well seen.

A coating agent such as wax is added to coat the plant powder and the polymer powder to facilitate physical mixing of the plant powder and to prevent excessive moisture absorption of the plant powder. As such a wax, PE wax is mainly used. Based on 100 parts by weight of the total amount of the plant body and the polymer or high molecular compound, 0.5 to 5 parts by weight, preferably 1 to 3 parts by weight, more preferably 1.5 to 2.5 parts by weight. can be used

In one embodiment of the present invention, a filler such as talc may be further added in an amount of 5 to 15 parts by weight based on 100 parts by weight of the total amount of the plant and the polymer or polymer compound.

In one embodiment of the present invention, 15 to 40 parts by weight of the biomass plasticization complex, 1 to 10 parts by weight of starch or modified starch, 45 to 75 parts by weight of the polymer, 1 to 2 parts by weight of the binder, and the remaining amount of additives may be used. there is.

6. Plasticization step

In step 1 of the present invention, the aforementioned starch-based biomass and lignocellulosic biomass are thermomechanically mixed or kneaded in the presence of a plasticizer, for example, 100 to 150 ° C., specifically 105 to 140 ° C., Preferably, the thermoplastic biomass composite can be prepared by extruding with a twin-screw extruder at a temperature of 110 to 120 °C.

During the thermomechanical mixing or kneading described above, not only the starch components of the biomass are plasticized, but also the biomass grains are more finely pulverized under the shear force of the twin-screw extruder, and dewatering occurs in the molecules, resulting in a homogeneous melt as a whole. As one of the advantageous advantages of the present invention, the resulting mixture is a miscible blend and can have a single glass transition temperature and a homogeneous state. The uniformity of the aforementioned miscible blends can be confirmed by electron microscopy.

The above-mentioned starch-based biomass is in the form of particles based on hydrogen bonding, and because of the hydroxyl group attached to the glucose unit, it is a hydrophilic material with excellent water adsorption properties. does not appear, and carbonization occurs in the range of about 220°C, and there is no bonding between polymers, and mechanical properties are poor due to poor interfacial adhesion. In order to solve this, a function of preventing bonding and carbonization by mixing cellulosic biomass in a certain ratio, strong in alkali, resistance to chemicals, and not erosion by microorganisms can be added.

In general, moisture is known to play a role in weakening the physical properties of the resin itself. In the case of non-edible plants, they absorb moisture while they are wet or stored after harvest. Such moisture later becomes an important cause of lowering the physical properties of the bioplastic.

Non-edible raw materials such as rice husk, soybean hull, jade hull, and wheat hull are pulverized using ACM (Air Classifying Mill).

The pulverized plant was dried with hot air at 100±5°C for 30 minutes to remove moisture using a dryer, for example, a cylindrical rotary dryer (model name: D560, manufacturer: Hwain Machinery, Wonju, Korea). The pulverized particles are small and porous, so they always retain moisture. This moisture is an important factor affecting the physical properties of bio-based plastics. Therefore, the pulverized plant is preferably dried until the moisture content is 0.3 ppm or less, preferably 0.2 ppm or less.

In the present invention, the non-edible plant is rice husk. Soybean hull, wheat husk, jade hull, rice straw, wheat straw, reed. shy. bamboo. wood flour. Coffee meal, soybean meal, cellulose, etc. may be exemplified, and it is preferable to mainly use rice husk, jade skin, wheat skin, and the like. These non-edible plants may be used alone, or two or more kinds of plants, specifically, two to four kinds of plants may be mixed and used.

In the present invention, in the production of bioplastics, a biomass plasticizing composite powder is first made, moisture is removed as much as possible, and then incorporated into a matrix made of a polymer or a high molecular compound. Although the method of making the starch-based biomass and the lignocellulosic biomass into a plasticized composite powder and the powder particle size are not strictly limited, it is usually pulverized and classified into 200 to 400 mesh using an ACM grinder or the like.

Figure 2 shows a schematic diagram of an ACM (Air Classifying Mill) device generally used for pulverizing and classifying non-edible plants. When the particle size is 200 mesh or less, the bonding between the polymer and the polymer is farther away because the particles are too large, and the physical properties are weakened due to this problem. When the particle size is 400 mesh or less, the portion that affects the plastic properties is reduced and better properties can be exhibited.

In the present invention, both lignocellulosic biomass and starch-based biomass are dried to have a particle size of 100 to 200 mesh and a moisture content of 5 to 6%, and step 1 of the present invention (production of biomass plasticization complex) ) and used in the subsequent step 2 (first low-temperature grinding step). Even if the plant body is pulverized and dried to a moisture content lower than 5-6%, the moisture content can be increased to 8-10% by absorbing moisture in the process of transport and storage in the air. The moisture content of the plant powder can be selected from a wide range. However, if the plant body introduced into the complex manufacturing step contains too much moisture, not only takes a lot of processing time and energy in the complexing step, but also causes a problem in binding to the polymer in the first low-temperature grinding 2), so the above range It is preferable to dry it to have a moisture content of

7. Primary low-temperature grinding and secondary cold grinding

According to one aspect of the present invention, the present invention introduces a biomass plasticization composite in a powder state and a polymer in a powder state together with a binder and an additive into a grinder, and 1 in a high-speed rotation or high-speed circulation method at a temperature of 80 to 150 ° C. Low-temperature grinding with tea (step 1), rapid cooling of the obtained mixture to a temperature of -20 to -5° C., and secondary cold grinding with high-speed rotation or high-speed circulation while maintaining this temperature (step 2), It is possible to provide a composite powder in which a mass plasticized composite and a polymer in a powder state are combined.

7-1. 1st low temperature grinding

The first low-temperature grinding step (step 1) according to the present invention is 800 to 2000 rpm, preferably 1000 to 2000 rpm, using a rotary mill, impact mill or air flow mill commonly used at a relatively low temperature of 70 to 140 ° C. It may be carried out at a speed of 1800 rpm, more preferably 1200 to 1500 rpm.

When a rotary mill is used, the blade or disk is rotated at the above speed, and when an impact mill is used, the powder particles are circulated at the speed and collided with the impact plate. This is done by circulating the blades together with the airflow at this speed and impinging on the blades attached to the wall. Accordingly, the speed means the rotation speed of blades in the rotary mill, the number of collisions on the impact plate in the impact mill, and the circulation speed of the air flow in the airflow mill.

If the rotation and circulation rates are lower than the above ranges, the binding of the biomass plasticized composite powder and the polymer powder is insufficient, and there is a risk of particle separation in the subsequent freeze drying and extrusion steps. There is a risk of damage or excessive heat generation.

The primary low-temperature grinding (step 2) according to the present invention is generally performed within a temperature range of 70 to 140° C., preferably within a temperature range of 90 to 140° C., more preferably at a temperature below the melting point of the polymer. , in particular, can be selected at a temperature near the softening point while being higher than the heat deflection temperature of the polymer.

In the present invention, by performing the first low-temperature pulverization at a temperature near the softening point of the polymer while higher than the heat deflection temperature of the polymer, the mechanical bonding strength of the biomass plasticized composite powder and the polymer powder can be further improved. At this time, since the plant powder is obtained by plasticizing and complexing lignocellulosic biomass and starch-based biomass, the primary low-temperature grinding temperature can be set approximately 5 to 15 ° C lower than when lignocellulosic biomass powder is used alone.

One of the advantages obtained by performing the primary low-temperature grinding according to the present invention in a manner of high-speed rotation or high-speed circulation in a collision type or rotary crusher is that even when the softening point of the polymer is higher than the above range, high temperature up to 140°C The point is that the plant powder and the polymer powder can be physically combined or aggregated by high-speed rotation or circulation in the .

As an example of setting the primary low-temperature grinding temperature according to the type of polymer, the polypropylene (PP) homopolymer has a melting point of 165°C, a heat denaturation temperature of 107-135°C, and a softening point (Vicat) of 145-155°C. High-density polyethylene (HDPE) has a melting point of 125 to 130 ° C, a heat denaturation temperature of 80 to 90 ° C, and a softening point (Vicat) of 110 to 128 ° C. In addition, low-density polyethylene (LDPE) has a melting point of 100 to 110 ° C, a heat denaturation temperature of 40 to 45 ° C, and a softening point (Vicat) of 74 to 85 ° C. It can be carried out at °C.

In the present invention, after the first low-temperature pulverization, the biomass plasticization composite and polypropylene may be mechanically combined or aggregated to obtain a granular mixture. They have a particle size of approximately 100 to 200 microns, but the particle size distribution is very wide, making it difficult to specify an exact size. The obtained granular mixture can be used as such in the secondary cold grinding step.

7-2. Secondary Cold Grinding

The secondary freeze grinding (step 3) according to the present invention may be performed at a low temperature of -30 ° C. to 0 ° C. at a speed of 800 to 2000 rpm, using a general cold grinder or freeze grinder.

In the present technical field, cryogenic grinding and freeze grinding use cryogenic refrigerants such as liquefied air or liquid nitrogen, but cold grinding is performed at a low temperature of -50 °C to 0 °C, and freeze grinding is performed at a cryogenic temperature of -150 °C to -50 °C. It can be divided into performing a pulverization process, and in some cases, cold pulverization is also referred to as low-temperature pulverization.

The freeze grinder or freeze grinder may perform grinding in a rotary, impact, or airflow type. If the rotation and circulation speed in the freeze grinding is lower or higher than the above range, the removal of moisture is not sufficient, and the grafting of the plant and the polymer is insufficient, and there is a risk of component separation in the subsequent extrusion step.

The secondary cold grinding step (step 3) according to the present invention is generally within a temperature range of -30 to 0°C, preferably -20 to -5°C, more preferably a temperature of -15 to -10°C. In, 800 to 2000 rpm, preferably 1000 to 1800 rpm, more preferably 1200 to 1500 rpm may be performed at a speed (rotational speed or circulation speed).

When the freezing temperature is lower than the above range, aggregation or bonding of particles is delayed even by high-speed rotation or circulation, and when the freezing temperature is higher than the above range, the effect of freezing grinding cannot be sufficiently obtained.

In the present invention, after the secondary cold pulverization, raw materials such as biomass plasticized composite, optional modified starch and polymer are composited by mechanical bonding and grafting to obtain a powdery composite.

The particle size of the composite is not strictly limited, but may be adjusted to have generally 100 to 300 mesh, preferably 150 to 250 mesh, and more preferably about 200 mesh.

One of the advantages of the present invention is that the secondary freeze-pulverized powder has a sufficiently low moisture content that it does not need to undergo an additional drying process, and the moisture content is generally 3% by weight or less, preferably 1% by weight. Hereinafter, more preferably, it may be around 0.3% by weight.

8. Extrusion and Extrusion Equipment

In the extrusion step according to the present invention, the secondary freeze-pulverized powder may be supplied to a twin-screw extruder having a length-diameter ratio (LD ratio) of 60 or more and extruded at 130 to 170°C.

In the present invention, the secondary freeze-pulverized powder may be fed into the extruder through a feeder through a hopper, and it is preferable to feed into the extruder at a constant speed using a single screw feeder or a double screw feeder. If the feed rate is not constant, that is, if it is not supplied in a fixed amount, the temperature of the extrudate in the extruder fluctuates according to the moving speed, making temperature control difficult, and the thickness of the strand at the outlet is not constant or the cause of the breakage can be

The twin screw extruder used in the present invention may have a length-diameter ratio (LD ratio) of 60 or more, preferably 65 or more, and more preferably 70 or more.

According to an embodiment of the present invention, the length-diameter ratio (LD ratio) of the twin screw extruder may be selected from 60 to 120, preferably 65 to 100, more preferably 70 to 90. If the length-diameter ratio is less than the above range, the extrusion temperature must be raised for the compounding and extrusion of the bioplastic, thereby increasing the likelihood of carbonization occurring. There is a problem that it becomes disadvantageous.

In general, the conventional method for producing bioplastics uses a twin-screw extruder having a length-to-diameter ratio of usually 50 or less, usually 48, and performs the extrusion process at a temperature of 180 to 230 ° C. was difficult to prevent. However, in the present invention, by using a twin-screw extruder having a length-diameter ratio (LD ratio) of 60 to 120, preferably 65 to 100, more preferably 70 to 90, particularly around 72, 130 to 170 Extrusion could be performed at a relatively low temperature of ℃, thereby preventing carbonization of the plant.

The twin screw extruder according to the present invention has a length-diameter ratio (LD ratio) of 60 or more, compared to the conventional extruder set to have a temperature control section or a temperature sensing section of 8 to 9 zones, a temperature control section or a temperature sensing section can be set to 10 zones or more, preferably 11 zones or more, more preferably 12 zones or more, whereby the extrusion temperature can be more precisely controlled.

The twin-screw extruder according to the present invention may further include a cooling device for temperature control, for example, a cooling device through refrigerant circulation may be mentioned.

The twin-screw extruder according to the present invention may have a plurality of exhaust holes in the die to remove or discharge water vapor generated inside the extruder. By providing a reduced-pressure vacuum through the exhaust hole, water vapor generated during extrusion can be removed, thereby reducing bubbles generated in bioplastics, and bubbles generated in injection products such as food packaging containers in the subsequent injection process. can prevent Even if moisture is sufficiently removed before extrusion, moisture in the air is absorbed during storage and transport of raw materials, so it is important to remove moisture during extrusion.

In the present invention, the extrudate in the extruder is discharged through a die in a circular or square shape with an appropriate thickness, for example, 1-3 mm, preferably 1.5-2.5 mm. At this time, the temperature of the die may be set 30 to 80° C. higher than the extrusion temperature. It instantaneously applies high temperature to the strands passing through the die, thereby smoothing the strand's surface.

The strand discharged from the die is cooled by an air-cooling or water-cooling method similarly to general extrusion, and cut to an appropriate length, for example, 2-5 mm, to prepare a masterbatch. The obtained masterbatch is preferably stored in an airtight container.

Figure 3 is a schematic diagram showing the configuration of the extruder equipment that can be used in the present invention, Figure 4 is a schematic diagram showing the configuration of the hopper, kneader, die, etc. of the extruder that can be used in the present invention.

9. Preparation of masterbatch and film, sheet or container using same

The bioplastic obtained in the extrusion step according to the present invention may be produced in the form of a film, sheet or container by extrusion or injection as such.

In one embodiment of the present invention, the bioplastic can be used as a masterbatch and mixed with a masterbatch containing another biomass plasticization complex or a polymer that does not contain a biomass plasticization complex to produce a desired product, For example, it may be manufactured in the form of a film, sheet, or container by extrusion or injection, or the like. They can be used as food packaging materials or food packaging containers, preferably food packaging containers.

Biomass plasticization composite bioplastics may each have unique physical properties depending on the characteristics of the plant or plant mixture used for its preparation. For example, as lignocellulosic biomass, rice husk-containing bioplastic has high compressive strength, jade hull-containing bioplastic and soybean hull-containing bioplastic have medium compressive strength, and wheat hull-containing bioplastic has the weakest compressive strength. .

On the other hand, in the case of a bioplastic containing wheat blood as a woody biomass, the bending strength is very good and the surface smoothness is good.

In the present invention, a method for manufacturing other products including films, sheets and containers from bioplastics, for example, injection or extrusion methods and process conditions are not particularly limited, and methods and conditions commonly used in the art can be performed according to

When the final products such as films, sheets and containers prepared according to the present invention are manufactured using only bioplastics containing lignocellulosic biomass and starch-based biomass, the total biomass content is approximately 20 to 50% by weight. When it is prepared by appropriately mixing a polymer that does not contain a plant, it is preferable to properly adjust the mixing ratio so as to have a total biomass content of 10 to 30% by weight.

Hereinafter, the present invention will be described in more detail through examples. However, the following examples are for explaining the present invention in more detail, and the scope of the present invention is not limited by the following examples. The following examples can be appropriately modified and changed by those skilled in the art within the scope of the present invention.

Example

Preparation Example 1: Preparation of biomass plasticization complex

60 parts by weight of starch as a starch-based biomass, 35 parts by weight of cellulose fiber as a lignocellulosic biomass, 3 parts by weight of a plasticizer (sorbitol) and 2 parts by weight of an interfacial adhesion strengthening agent (PCL) are introduced into the twin-screw extruder, and each section (T1-T6 ) was controlled to 110±2℃, 115±2℃, 115±2℃, 115±2℃, 110±2℃, 110±2℃ to perform kneading and extrusion processes.

The extruded thermoplastic biomass composite was cut and obtained in the form of pellets (diameter of about 05 cm, length of 2-3 cm). The extruded thermoplastic biomass composite had a melt flow index of 0.92 g/10 min (ASTM D1238), a specific gravity of 0.95 (ASTM D792), a tensile strength of 48 kgf/cm ² (ASTM D638), and a flexural modulus of 10,100 kgf/cm ² (ASTM D790) and IZOD impact strength of 1.45 kgf·cm/cm ² (ASTM D256).

Preparation Example 2: Preparation of plasticized composite

As lignocellulosic biomass, rice husk powder, a non-edible plant, was introduced into a grinder (model: KH-1000; manufacturer: Korea Powder Machinery Co., Ltd.) and pulverized to a particle size of 200 μm.

A thermoplastic biomass composite was prepared in the same manner as in Preparation Example 1, except that 100 parts by weight of the rice hull powder as the lignocellulosic biomass and 30 parts by weight of starch as the starch-based biomass were used.

Example 1: Preparation of bioplastics containing lignocellulosic biomass and starch-based biomass

130 parts by weight of the thermoplastic biomass composite obtained in Preparation Example 1, 200 parts by weight of polypropylene, 3 parts by weight of calcium stearate, and 3 parts by weight of PE-Wax to a blade grinder (Model: KH-1000; Manufacturer: Korea Powder Machinery) It was introduced and first crushed for 30 minutes at a temperature of 130-135° C. at a rotation speed of 1500-2000 rpm.

The primary pulverized powder is subjected to an ultra-fine low-temperature grinder (model name: HKP-30, manufacturer: Korea Energy Technology) consisting of a raw material cooling unit, a supply unit, a grinding unit, a product collection unit, a cold heat (excess heat) recovery unit, a refrigerant supply unit, a control unit, etc. ) and cooled to -10°C, followed by high-speed stirring at 1500-2000 rpm for 30 minutes.

The obtained secondary pulverized powder was supplied to an extruder (model: YS-120Φx1800L; manufacturer: Yuseong Industrial Co., Ltd.) manufactured to have an LD ratio of 72 and 11 temperature zones at a constant speed using a single screw feeder. The extrusion temperature was controlled not to exceed 140° C., allowing rise to 160° C. in the final zone and die. Water vapor generated during extrusion was discharged under reduced pressure through a number of exhaust holes installed in the die.

The strands discharged from the extruder were cooled by air cooling, and the cooled strands were cut to 2-3 mm in length using a cutting machine to prepare bioplastics in the form of masterbatch chips. At this time, the strand was cut to a length of 2 to 4 mm while appropriately adjusting the pulling force so as not to break the strand according to the strand discharge speed in the cutter.

In the bioplastic obtained in the form of a masterbatch chip, the biomass content was about 38% (by weight), and no carbonization and breakage were observed.

Example 2: Preparation of bioplastics using rice husk as lignocellulosic biomass and starch as starch-based biomass

In the same manner as in Example 1, except that 130 parts by weight of the biomass plasticization complex obtained in Preparation Example 2 was used, a bioplastic was prepared in the form of a mastertatch chip.

In the resulting bioplastic masterbatch chip, the biomass content was approximately 34% (by weight), and carbonization and breakage were not observed.

Comparative Examples 1 and 2

Except for setting the extrusion temperature higher or lower than in Example 1, the same procedure as in Example 1 was carried out to prepare a bioplastic in the form of a masterbatch chip.

Carbonization and/or breakage were observed in the resulting bioplastic.

As can be seen in Examples 1 and 2 and Comparative Examples 1 and 2, controlling the temperature inside the extruder not to exceed 170° C. while maintaining it at 130° C. or higher was the most important for preventing carbonization and preventing strand breakage.

In Example 1, the temperature inside the extruder was generally controlled between 130 and 160°C. Carbonization of plants (woody biomass and starch-based biomass) was not observed in the bioplastic strands prepared at such a controlled temperature, and the strands were continuously discharged without interruption.

In Comparative Example 1, the temperature inside the extruder was generally maintained at 170°C, but in some sections, it exceeded this and reached 180°C. In the bioplastic produced in this way, it was confirmed that not only the carbonization of plants (woody biomass and starch-based biomass) but also the phenomenon of strand breakage occurred.

In Comparative Example 2, the extruder temperature was generally lowered to 130° C. or less in some sections. When the extrusion temperature was low, graft bonding and complexing between the raw materials were not performed properly, and a phenomenon in which a layer was formed on the strands was observed.

Example 3: Bioplastic using wheat flour powder as lignocellulosic biomass

100 parts by weight of a thermoplastic biomass composite was obtained in the same manner as in Preparation Example 1, except that 50 parts by weight of wheat flour and 50 parts by weight of starch were used.

It proceeded in the same manner as in Example 1, except that 400 parts by weight of polypropylene, 60 parts by weight of starch, 3 parts by weight of calcium stearate, and 3 parts by weight of PE-Wax were used with respect to 100 parts by weight of the thermoplastic biomass composite. The biomass content in the obtained masterbatch was approximately 28% (by weight).

The temperature inside the extruder was generally maintained at about 120 to 140 ° C. In the bioplastic produced in this way, carbonization of the plant was not observed, and the strand was continuously discharged without interruption.

Specific examples of the method for producing a bioplastic containing lignocellulosic biomass and starch-based biomass according to the present invention, the bioplastic produced thereby, and a film, sheet or container using the same have been described, but the present invention It is evident that various implementation modifications are possible within the limits not departing from the scope of

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the following claims as well as the claims and equivalents.

That is, it should be understood that the above-described embodiments are illustrative in all respects and not restrictive, and the scope of the present invention is indicated by the claims to be described later rather than the detailed description, and the meaning and scope of the claims; All changes or modifications derived from the concept of equivalents should be construed as being included in the scope of the present invention.

Claims (10)

(Step 1) thermomechanically mixing or kneading lignocellulosic biomass and starch-based biomass at a temperature of 100 to 130° C. in the presence of a plasticizer to prepare a biomass plasticization complex;
(Step 2) a first low-temperature pulverization step of pulverizing the biomass plasticization complex, the polymer and the binder at a temperature of 80 to 150° C. at a high speed of 1000 to 2500 rpm;
(Step 3) a secondary cold grinding step of grinding the first low-temperature pulverized powder at a temperature of -20 to 0° C. at a high speed of 1000 to 2500 rpm; and
(Step 4) an extrusion step of supplying the secondary freeze-pulverized powder to a twin-screw extruder having a length-diameter ratio (LD ratio) of 60 or more at a constant speed, and extruding while discharging water vapor generated at a temperature of 130 to 170° C. under reduced pressure; containing,
A method for producing bioplastics containing lignocellulosic biomass and starch-based biomass.
The method of claim 1,
The above-mentioned starch-based biomass, corn starch, potato starch, sweet potato starch, cassava starch, oxidized starch thereof, cationic starch, crosslinked starch, starch ester, such as modified starch or a combination thereof; Or plant seeds, stems, roots, and leaves, flour, corn flour, rice flour, glutinous rice flour, potato flour, sweet potato flour, cassava flour, or a combination thereof, characterized in that selected from,
A method for producing bioplastics containing lignocellulosic biomass and starch-based biomass.
The method of claim 1,
The aforementioned lignocellulosic biomass may include rice husk, soybean hull, wheat hull, jade hull, rice hull, wheat bran, reed, mugwort, bamboo, wood flour, coffee hull, soybean meal, mixtures thereof, or a pulverized product thereof; Wood fiber, cotton fiber, grass fiber, reed fiber, bamboo fiber, modified products thereof, carboxymethyl cellulose, carboxyethyl cellulose, cellulose ester, cellulose ether, and combinations thereof; characterized in that selected from the group consisting of;
A method for producing bioplastics containing lignocellulosic biomass and starch-based biomass.
The method of claim 1,
The polymer is an olefin-based polymer selected from polypropylene, polyethylene or polystyrene; vinyl-based polymers; amide-based polymers; Characterized in that it comprises at least one selected from the group consisting of ester-based polymers, copolymers thereof, mixtures thereof, modified products thereof, and alloys thereof,
A method for producing bioplastics containing lignocellulosic biomass and starch-based biomass.
The method of claim 1,
In step 1 described above,
Biomass plasticization complex is characterized by thermomechanically mixing or kneading 20 to 80 parts by weight of starch-based biomass and 20 to 80 parts by weight of lignocellulosic biomass at a temperature of 100 to 130° C. in the presence of 1 to 10 parts by weight of plasticizer doing,
A method for producing bioplastics containing lignocellulosic biomass and starch-based biomass.
The method of claim 1,
In step 1 described above,
The biomass plasticization complex is characterized in that the water content is controlled to 5% or less.
doing,
A method for producing bioplastics containing lignocellulosic biomass and starch-based biomass.
The method of claim 1,
In step 2 described above,
It is characterized in that it is used in an amount of 20 to 50 parts by weight of the biomass plasticization complex, 50 to 80 parts by weight of the polymer, and 1 to 5 parts by weight of the binder,
A method for producing bioplastics containing lignocellulosic biomass and starch-based biomass.
The method of claim 1,
In step 2 described above,
The binder is characterized in that at least one selected from the group consisting of a silane-based coupling agent, a titanium-based coupling agent, and a zirconium-based coupling agent,
A method for producing bioplastics containing lignocellulosic biomass and starch-based biomass.
A bioplastic produced by the method according to any one of claims 1 to 8, and containing lignocellulosic biomass and starch-based biomass.
A food packaging container using the bioplastic containing the lignocellulosic biomass and the starch-based biomass according to claim 9.

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