KR20230166931A - Biodegradable water-based dispersion using same and preparation method thereof - Google Patents

Abstract

The present invention relates to biodegradable aqueous dispersion compositions and methods for their preparation. Specifically, according to one embodiment of the present invention, the biodegradable aqueous dispersion composition includes polyhydroxyalkanoate, cellulose nanofibers, or carboxymethylcellulose; and water, and in particular, the cellulose nanofibers include oxidized cellulose nanofibers or enzyme-treated and oxidized cellulose nanofibers, so that they are environmentally friendly due to excellent biodegradability and biocompatibility, as well as viscosity characteristics, dispersibility, and coating. Performance and storage stability can be improved. Therefore, when a biodegradable article including a coating layer prepared using the biodegradable aqueous dispersion composition is applied to articles requiring oil resistance, such as food packaging materials for packaging oily foods, it can exhibit excellent properties.

Description

Biodegradable water-based dispersion composition and method for producing the same {BIODEGRADABLE WATER-BASED DISPERSION USING SAME AND PREPARATION METHOD THEREOF}

The present invention relates to biodegradable aqueous dispersion compositions and methods for their preparation.

Recently, as concerns about environmental issues have increased, research on the treatment and recycling of various household waste has been actively conducted. Specifically, polymer materials that are inexpensive and have excellent properties such as processability are widely used to manufacture various products such as paper, film, fiber, packaging materials, bottles, containers, etc. However, when these products reach the end of their lifespan, they are harmful when incinerated. It has the disadvantage that substances can be released and that it takes hundreds of years depending on the type to completely decompose naturally.

Accordingly, biodegradable polymers can improve eco-friendliness by decomposing quickly, while increasing the lifespan of the product itself by improving mechanical properties, oil resistance, water resistance, and processability, thereby reducing the amount of waste or improving recyclability. Research on this is continuing.

Polyhydroxyalkanoates (PHA) are biodegradable polymers composed of several types of hydroxy carboxylic acids produced by numerous microorganisms and used as intracellular storage substances. Polyhydroxyalkanoates are polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), and polybutylene succinate derived from conventional petroleum. It has similar physical properties to synthetic polymers such as terephthalate (PBST) and polybutylene succinate adipate (PBSA), is completely biodegradable, and has excellent biocompatibility.

Meanwhile, in order to improve the service life and recyclability of various products such as paper, film, fiber, packaging materials, bottles, containers, etc., it is important to improve mechanical properties such as strength, oil resistance, and water resistance. In particular, food packaging materials that pack foods with a lot of moisture or oil, such as fruits, vegetables, bread, cookies, ice cream, etc., have problems with moisture or oil seeping from the food, tearing the packaging material, contaminating the food, or having a short service life.

In order to improve these mechanical properties, water resistance, and oil resistance, a process of forming a coating layer on the surface of the product is used, but there is a problem that biodegradability and recyclability are reduced due to the coating layer. For example, the biodegradability of the coating layer component that can improve water resistance and oil resistance is low, or even if the biodegradability of the coating layer is excellent, the lifespan of the product may be poor due to low storage stability, and the coating layer may be removed from the surface of a used product. Additional processes may be required to do this. Therefore, research is continuing on biodegradable dispersions that are environmentally friendly due to their excellent biodegradability and biocompatibility, and have excellent dispersibility, storage stability, water resistance, oil resistance, coating properties, and processability.

Korean Patent Publication No. 2012-0103158

Therefore, the present invention provides a biodegradable aqueous dispersion composition that is environmentally friendly due to its excellent biodegradability and biocompatibility, and has excellent dispersibility and storage stability, which can improve the lifespan of biodegradable articles using it, and also has excellent coating properties, oil resistance, and processability. The purpose is to provide a manufacturing method thereof.

The biodegradable aqueous dispersion composition according to an embodiment of the present invention includes polyhydroxyalkanoate; Cellulose nanofibers or carboxymethyl cellulose; and water, and no agglomeration or precipitation occurs when heated at a temperature of 50°C for one week and then redispersed with a mixer.

According to one embodiment of the present invention, when the biodegradable aqueous dispersion composition is heated at a temperature of 50° C. for 2 weeks and then redispersed with a mixer, agglomeration or precipitation may not occur, and measured according to TAPPI UM 557. The oil resistance kit rating may be 4 or higher.

According to one embodiment of the present invention, the cellulose nanofibers may include oxidized cellulose nanofibers, enzyme-treated and oxidized cellulose nanofibers, or microfibrillated cellulose.

According to one embodiment of the present invention, the cellulose nanofibers may have a width of 100 nm or less, a length of 200 nm or more, an aspect ratio of 2 to 500, and a carboxyl group content of 0.01 mmol/g to 2.00 mmol/g. It may be g.

According to one embodiment of the present invention, the carboxymethyl cellulose may have a carboxymethyl group content of 3.00 mmol/g to 8.00 mmol/g and a viscosity of 2,000 cps to 5,000 cps.

According to one embodiment of the present invention, the biodegradable aqueous dispersion composition may contain 0.01% by weight or more of the cellulose nanofibers or carboxymethyl cellulose based on the total weight.

According to one embodiment of the present invention, the polyhydroxyalkanoate is 3-hydroxybutyrate (3-HB), 4-hydroxybutyrate (4-HB), 3-hydroxypropionate (3-HP) ), 3-hydroxyhexanoate (3-HH), 3-hydroxyvalerate (3-HV), 4-hydroxyvalerate (4-HV), 5-hydroxyvalerate (5-HV) and 6-hydroxyhexanoate (6-HH).

According to one embodiment of the present invention, the polyhydroxyalkanoate is a polyhydroxyalkanoate comprising a 4-hydroxybutyrate (4-HB) repeating unit and a 3-hydroxybutyrate (3-HB) repeating unit. As an ate copolymer, it may contain 0.1% by weight to 60% by weight of the 4-hydroxybutyrate (4-HB) repeating unit.

According to one embodiment of the present invention, the polyhydroxyalkanoate may include the first PHA.

According to one embodiment of the present invention, the first PHA may include 0.1% by weight to 30% by weight of 4-hydroxybutyrate (4-HB) repeating unit, and has a glass transition temperature (Tg) of -30. It may be from ℃ to 80℃, the crystallization temperature (Tc) may be from 70℃ to 120℃, and the melting temperature (Tm) may be from 105℃ to 165℃.

According to one embodiment of the present invention, the polyhydroxyalkanoate may be included in an amount of 10% by weight to 80% by weight based on the total weight of the biodegradable aqueous dispersion composition.

According to one embodiment of the present invention, the biodegradable aqueous dispersion composition may include a dispersant, and the content of the dispersant may be 0.01% by weight to 30% by weight based on the total weight of solids of the biodegradable aqueous dispersion composition. there is.

A method for producing a biodegradable aqueous dispersion composition according to another embodiment of the present invention includes obtaining a polyhydroxyalkanoate suspension; And mixing and stirring the polyhydroxyalkanoate suspension and cellulose nanofibers or carboxymethyl cellulose.

According to another embodiment of the present invention, the polyhydroxyalkanoate suspension can be obtained by mixing and stirring polyhydroxyalkanoate, a dispersant, and water.

According to another embodiment of the present invention, the cellulose nanofibers may include oxidized cellulose nanofibers, enzyme-treated and oxidized cellulose nanofibers, or microfibrillated cellulose.

A method for producing cellulose nanofibers according to another embodiment of the present invention includes the steps of (1) adjusting the pH of biomass containing cellulose to 3.5 to 6.5; (2) enzymatic treatment by adding enzyme and reacting at a temperature of 35°C or higher; and (3) oxidation treatment.

According to another embodiment of the present invention, step (2) is a step of enzymatic treatment by adding an enzyme and performing a primary reaction at a temperature of 35 ℃ to 60 ℃, raising the temperature to 65 ℃ or more and performing a secondary reaction. You can.

According to another embodiment of the present invention, in step (2), enzymes may be added in an amount of 100 unit/g to 500 unit/g, and the enzymes include xylanase and mannanase. , may include one or more selected from the group consisting of endoglucanase and exoglucanase.

According to another embodiment of the present invention, step (3) may be performed by adding at least one oxidizing agent selected from the group consisting of NaClO, NaClO ₂ , H ₂ O ₂ and O ₃ .

According to another embodiment of the present invention, in step (3), the additive may be added in an amount of 0.01 mmol/g to 20.00 mmol/g, the additive includes a catalyst, and the catalyst includes 2,2, It may be one or more selected from the group consisting of 6,6-tetraalkylpiperidine-1-oxyl (TEMPO), NaBr, KBr, and HBr.

The biodegradable aqueous dispersion composition according to an embodiment of the present invention contains polyhydroxyalkanoate, cellulose nanofibers or carboxymethyl cellulose, and water, and thus has excellent biodegradability and biocompatibility, making it environmentally friendly and having viscosity characteristics and dispersibility. , coating properties and storage stability can be improved. Specifically, when heated at a temperature of 50°C for one week and then redispersed with a mixer, no agglomeration or precipitation occurs, so it has excellent storage stability.

More specifically, by applying specific cellulose nanofibers or carboxymethyl cellulose suitable for specific polyhydroxyalkanoate, oil resistance and storage stability can be improved without deteriorating biodegradability or biocompatibility.

In particular, oil resistance and storage stability can be further improved by the cellulose nanofibers including oxidized cellulose nanofibers or enzyme-treated and oxidized cellulose nanofibers.

Therefore, the biodegradable aqueous dispersion composition not only has excellent dispersibility, coating properties, and processability, but also biodegradable products manufactured using it can be applied to products that require oil resistance, such as food packaging materials for packaging oily foods. In this case, excellent characteristics can be exhibited. In addition, the biodegradable aqueous dispersion composition has excellent viscosity characteristics and storage stability, which can improve the lifespan of biodegradable products using it.

Hereinafter, the present invention will be described in detail. The present invention is not limited to the content disclosed below, and may be modified into various forms as long as the gist of the invention is not changed.

In this specification, when a part “includes” a certain component, this means that it may further include other components rather than excluding other components, unless specifically stated to the contrary.

All numbers and expressions indicating the amounts of components, reaction conditions, etc. described in this specification should be understood as being modified by the term “about” in all cases unless otherwise specified.

In this specification, when one component is described as being formed on or under another component, it means that one component is formed directly on or under the other component, or indirectly through another component. Includes.

In this specification, terms such as first, second, primary, and secondary are used to describe various components, and the components are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

Biodegradable aqueous dispersion composition

The biodegradable aqueous dispersion composition according to an embodiment of the present invention includes polyhydroxyalkanoate; Cellulose nanofibers or carboxymethyl cellulose; and water, and no agglomeration or precipitation occurs when heated at a temperature of 50°C for one week and then redispersed with a mixer.

Specifically, the biodegradable aqueous dispersion composition according to an embodiment of the present invention has excellent storage stability because no agglomeration or precipitation occurs when redispersed with a mixer after being heated at a temperature of 50°C for one week. Additionally, when the biodegradable aqueous dispersion composition is heated at a temperature of 50° C. for 2 weeks and then redispersed with a mixer, agglomeration or precipitation may not occur.

More specifically, the biodegradable aqueous dispersion composition has excellent storage stability and oil resistance, such as long-term storage stability and redispersibility, and the biodegradable aqueous dispersion composition is heated in an oven at 50° C. for 1 week or 2 weeks and mixed with a vortex mixer. After applying shear stress at 3,200 rpm using a vortex mixer (product name: SI-0246A manufacturer: scientific industries), the composition did not clump up and did not precipitate when the bottom surface was scraped with a spoon. No.

The viscosity of the biodegradable aqueous dispersion composition may be 100 mPa·s to 3,000 mPa·s. For example, the viscosity of the biodegradable aqueous dispersion composition is 100 mPa·s to 2,500 mPa·s, 130 mPa·s to 2,000 mPa·s, 150 mPa·s to 1,800 mPa·s, 190 mPa·s to 1,600 mPa. ·s, 200 mPa·s to 1,500 mPa·s, 230 mPa·s to 1,400 mPa·s or 260 mPa·s to 1,350 mPa·s.

Additionally, the solid content of the biodegradable aqueous dispersion may be 10% by weight to 80% by weight. For example, the solid content of the biodegradable aqueous dispersion is 10% to 70% by weight, 12% to 60% by weight, 15% to 55% by weight, 20% to 55% by weight, 25% to 50% by weight. It may be % by weight, 30% by weight to 45% by weight, or 35% by weight to 45% by weight.

The average particle size of the polyhydroxyalkanoate in the biodegradable aqueous dispersion may be 0.5 ㎛ to 5 ㎛. For example, the average particle size of the polyhydroxyalkanoate in the biodegradable aqueous dispersion is 0.7 ㎛ to 4.6 ㎛, 1.1 ㎛ to 4.5 ㎛, 1.5 ㎛ to 4.3 ㎛, 2.2 ㎛ to 4.2 ㎛, 2.6 ㎛ to 4.0 ㎛. ㎛, 2.8 ㎛ to 3.9 ㎛ or 3.1 ㎛ to 3.8 ㎛.

Polyhydroxyalkanoate

The biodegradable aqueous dispersion according to an embodiment of the present invention includes polyhydroxyalkanoate (PHA).

The PHA is a thermoplastic natural polyester polymer that accumulates in microbial cells. Since it is a biodegradable material, PHA can be composted and can ultimately be decomposed into carbon dioxide, water, and organic waste without generating toxic waste.

Specifically, PHA is a thermoplastic natural polyester polymer that accumulates within microbial cells. When certain bacteria are unbalanced with nutrients (nitrogen source, phosphorus, etc.), they accumulate PHA within cells to store carbon sources and energy. It is formed by doing

In addition, the PHA is polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate terephthalate (PBST), and polybutylene succinate adipate (PBAT) derived from existing petroleum. It has similar physical properties to synthetic polymers such as (PBSA), is completely biodegradable, and has excellent biocompatibility.

In particular, unlike other eco-friendly plastic materials such as PBS, PLA, and PTT, PHA can be synthesized from more than 150 types of monomers, so hundreds of types of PHA can be manufactured depending on the type of monomer, and different types of PHA can be produced depending on the type of monomer. Hundreds of types of PHAs each have completely different structures and properties.

The PHA may be composed of a single monomer repeating unit within living cells, or may be formed by polymerizing one or more monomer repeating units. Specifically, the PHA may be a single polyhydroxyalkanoate (hereinafter referred to as HOMO PHA), and a polyhydroxyalkanoate copolymer (hereinafter referred to as PHA copolymer), i.e., may have different polymer chains. It may be a copolymer in which repeating units are randomly distributed.

Examples of repeating units that may be included in the PHA include 2-hydroxybutyrate, lactic acid, glycolic acid, 3-hydroxybutyrate (hereinafter referred to as 3-HB), 3-hydroxypropionate (hereinafter referred to as 3) -HP), 3-hydroxyvalerate (hereinafter referred to as 3-HV), 3-hydroxyhexanoate (hereinafter referred to as 3-HH), 3-hydroxyheptanoate (hereinafter referred to as 3-HH) Hereinafter referred to as 3-HHep), 3-hydroxyoctanoate (hereinafter referred to as 3-HO), 3-hydroxynonanoate (hereinafter referred to as 3-HN), 3-hydroxy Decanoate (hereinafter referred to as 3-HD), 3-hydroxydodecanoate (hereinafter referred to as 3-HDd), 4-hydroxybutyrate (hereinafter referred to as 4-HB), 4- Hydroxyvalerate (hereinafter referred to as 4-HV), 5-hydroxyvalerate (hereinafter referred to as 5-HV), and 6-hydroxyhexanoate (hereinafter referred to as 6-HH) There may be, and the PHA may contain one or more repeating units selected from these.

Specifically, the PHA is 3-HB, 4-HB, 3-HP, 3-HH. It may include one or more repeating units selected from the group consisting of 3-HV, 4-HV, 5-HV and 6-HH.

More specifically, the PHA may contain 0.1% to 100% by weight of the 4-HB repeating unit. For example, the PHA contains 4-HB repeating units in an amount of 0.2% to 100% by weight, 0.5% to 100% by weight, 1% to 100% by weight, 5% to 100% by weight, and 10% to 100% by weight. Weight %, 20 weight % to 100 weight %, 30 weight % to 100 weight %, 40 weight % to 100 weight %, 50 weight % to 100 weight %, 60 weight % to 100 weight %, 70 weight % to 100 weight % , 80% to 100% by weight, 90% to 100% by weight, 0.1% to 25% by weight, 0.2% to 22% by weight, 0.5% to 20% by weight, 1% to 18% by weight, 2 It may be included in weight% to 16% by weight, 3% to 15% by weight, 5% to 13% by weight, or 8% to 12% by weight. The PHA may be a HOMO PHA consisting only of 4-HB repeating units, or a PHA copolymer containing 4-HB repeating units.

In addition, the PHA includes a 4-HB repeating unit and additionally includes one repeating unit different from the 4-HB, or 2, 3, 4, 5, 6 or more repeats that are different from each other. It may be a PHA copolymer further comprising units. For example, the PHA may be poly 3-hydroxybutyrate-co-4-hydroxybutyrate (hereinafter referred to as 3HB-co-4HB).

Additionally, the PHA may include isomers. For example, the PHA may include structural isomers, enantiomers, or geometric isomers. Specifically, the PHA may include structural isomers.

Additionally, the PHA may be a PHA copolymer with controlled crystallinity. For example, the PHA may include at least one 4-HB repeating unit, and the crystallinity of the PHA can be adjusted by controlling the content of the 4-HB repeating unit.

For example, the PHA is 3-hydroxybutyrate (3-HB), 4-hydroxybutyrate (4-HB), 3-hydroxypropionate (3-HP), 3-hydroxyhexanoate ( 3-HH), 3-hydroxyvalerate (3-HV), 4-hydroxyvalerate (4-HV), 5-hydroxyvalerate (5-HV) and 6-hydroxyhexanoate (6 It may be a PHA copolymer containing one or more repeating units selected from the group consisting of -HH).

Specifically, the PHA copolymer includes a 4-HB repeating unit, a 3-HB repeating unit, a 3-HP repeating unit, a 3-HH repeating unit, a 3-HV repeating unit, a 4-HV repeating unit, and a 5-HV repeating unit. It may further include one or more types of repeating units selected from the group consisting of repeating units and 6-HH repeating units. More specifically, the PHA copolymer may include a 4-HB repeating unit and a 3-HB repeating unit.

More specifically, the PHA is a PHA copolymer containing a 4-HB repeating unit and a 3-HB repeating unit, and may include the 4-HB repeating unit in an amount of 0.1% to 60% by weight. For example, the PHA may contain the 4-HB repeating unit in an amount of 0.1% to 55% by weight, 0.5% to 50% by weight, 1% to 48% by weight, 2% to 45% by weight, or 5% to 5% by weight. 35% by weight, 6% to 20% by weight, 8% to 15% by weight, 9% to 12% by weight, 0.1% to 25% by weight, 0.2% to 22% by weight, 0.5% to 20% by weight %, 1% to 18% by weight, 2% to 16% by weight, 3% to 15% by weight, 5% to 13% by weight, or 8% to 12% by weight.

In addition, the PHA is a PHA copolymer containing a 4-HB repeating unit and a 3-HB repeating unit, and may contain 20% by weight or more of the 3-HB repeating unit. For example, the PHA may contain more than 35% by weight, more than 40% by weight, more than 50% by weight, more than 60% by weight, more than 70% by weight, or more than 75% by weight, 99 Weight% or less, 98 weight% or less, 97 weight% or less, 96 weight% or less, 95 weight% or less, 93 weight% or less, 91 weight% or less, 90 weight% or less, 80 weight% or less, 70 weight% or less, 60 It may be included in less than 55% by weight or less than 55% by weight.

The PHA with controlled crystallinity may have its crystallinity and amorphousness adjusted by increasing the irregularity in the molecular structure. Specifically, it may be one by adjusting the type or ratio of monomers or the type or content of isomers.

According to one embodiment of the present invention, the PHA may include two or more types of PHA with different crystallinity. Specifically, the PHA may be adjusted to have the content of the 4-HB repeating unit within the specific range by mixing two or more types of PHAs with different crystallinities.

Specifically, the PHA may include a first PHA that is a semi-crystalline PHA.

The first PHA is a semi-crystalline PHA with controlled crystallinity (hereinafter referred to as scPHA), and may include 0.1% by weight to 30% by weight of a 4-HB repeating unit. For example, the first PHA contains 4-HB repeating units in an amount of 0.1% to 30% by weight, 0.5% to 30% by weight, 1% to 30% by weight, 3% to 30% by weight, 1% by weight. to 28% by weight, 1% to 25% by weight, 1% to 24% by weight, 1% to 15% by weight, 2% to 25% by weight, 3% to 25% by weight, 3% to 24% by weight It may be included in weight%, 5% to 24% by weight, 7% to 20% by weight, 10% to 20% by weight, 15% to 25% by weight, or 15% to 24% by weight.

The glass transition temperature (Tg) of the first PHA is -30°C to 80°C, -30°C to 10°C, -25°C to 5°C, -25°C to 0°C, -20°C to 0°C, or -15°C. It may be from 0°C. The crystallization temperature (Tc) of the first PHA may be 70°C to 120°C, 75°C to 120°C, or 75°C to 115°C, and the melting temperature (Tm) may be 105°C to 165°C, 110°C to 160°C, It may be 115°C to 155°C or 120°C to 150°C. Additionally, the cold crystallization temperature (Tcc) of the first PHA resin may not be measured, or may be 35°C to 125°C, 35°C to 120°C, 45°C to 110°C, or 55°C to 100°C.

In this specification, the glass transition temperature (Tg), crystallization temperature (Tc), melting temperature (Tm), and cold crystallization temperature (Tcc) may be measured using differential scanning calorimetry (DSC). Specifically, the glass transition temperature (Tg), crystallization temperature (Tc), and melting temperature (Tm) can be measured by 1st scan or 2nd scan in differential scanning calorimetry (DSC) mode. This can be confirmed from the heat flow curve obtained by scanning. More specifically, the glass transition temperature (Tg) and crystallization temperature (Tc) are obtained from the heat flow curve obtained by increasing the temperature from 40°C to 180°C at a rate of 10°C/min and then cooling to -50°C at a rate of 10°C/min. , melting temperature (Tm) and cold crystallization temperature (Tcc) can be confirmed.

In addition, the first PHA resin may have a melt flow index of 0.1 g/10min to 15 g/10min measured at 165°C and 5 kg according to ASTM D1238. For example, the first PHA resin has a melt flow index of 0.1 g/10min to 10 g/10min, 0.2 g/10min to 7 g/10min, and 0.5 g/10min measured at 165°C and 5 kg according to ASTM D1238. to 5.5 g/10min, 0.6 g/10min to 5 g/10min, 0.8 g/10min to 5 g/10min, 1 g/10min to 5 g/10min, 0.1 g/10min to 5 g/10min, 1 g/10min to 6.5 g/10min, 1.5 g/10min to 15 g/10min, 3 g/10min to 10 g/10min, 3.5 g/10min to 12 g/10min, or 4.5 g/10min to 10 g/10min.

The weight average molecular weight of the first PHA is 10,000 g/mol to 1,200,000 g/mol, 50,000 g/mol to 1,100,000 g/mol, 100,000 g/mol to 1,000,000 g/mol, 100,000 g/mol to 900,000 g/mol, 200,000 g /mol to 800,000 g/mol, 200,000 g/mol to 600,000 g/mol, or 200,000 g/mol to 400,000 g/mol.

Additionally, the PHA may include a second PHA, which is an amorphous PHA with controlled crystallinity.

The second PHA is an amorphous PHA with controlled crystallinity (hereinafter referred to as aPHA), and contains 4-HB repeating units in an amount of 15% to 60% by weight, 15% to 55% by weight, and 20% to 55% by weight. %, 25% to 55% by weight, 30% to 55% by weight, 35% to 55% by weight, 20% to 50% by weight, 25% to 50% by weight, 30% to 50% by weight, It may contain 35% to 50% by weight or 20% to 40% by weight.

The glass transition temperature (Tg) of the second PHA may be -45°C to -10°C, -35°C to -15°C, -35°C to -20°C, or -30°C to -20°C. Additionally, the crystallization temperature (Tc) of the second PHA may not be measured, or may be 60°C to 120°C, 60°C to 110°C, 70°C to 120°C, or 75°C to 115°C. The melting temperature (Tm) of the second PHA may not be measured, or may be 100°C to 170°C, 100°C to 160°C, 110°C to 160°C, or 120°C to 150°C. Additionally, the cold crystallization temperature (Tcc) of the second PHA resin may not be measured, or may be 30°C to 125°C, 30°C to 120°C, 40°C to 110°C, or 50°C to 100°C.

The second PHA resin may have a melt flow index (MFI) of 0.1 g/10min to 20 g/10min measured at 165°C and 5 kg according to ASTM D1238. For example, the second PHA resin has a melt flow index of 0.1 g/10min to 15 g/10min, 0.1 g/10min to 12 g/10min, and 0.1 g/10min measured at 165°C and 5 kg according to ASTM D1238. to 10 g/10min, 0.1 g/10min to 8 g/10min, 0.1 g/10min to 6 g/10min, 0.1 g/10min to 5.5 g/10min, 0.5 g/10min to 10 g/10min, 1 g/10min to 10 g/10min, 2 g/10min to 8 g/10min, 3 g/10min to 6 g/10min or 3 g/10min to 5.5 g/10min.

The average molecular weight of the second PHA is 10,000 g/mol to 1,200,000 g/mol, 10,000 g/mol to 1,000,000 g/mol, 50,000 g/mol to 1,000,000 g/mol, 200,000 g/mol to 1,200,000 g/mol, 300,000 g/mol to 1,000,000 g/mol, 100,000 g/mol to 900,000 g/mol, 500,000 g/mol to 900,000 g/mol, 200,000 g/mol to 800,000 g/mol, or 200,000 g/mol to 400,000 g/mol. there is.

The first PHA and the second PHA can be distinguished depending on the content of the 4-HB repeating unit, and are selected from the group consisting of the glass transition temperature (Tg), the crystallization temperature (Tc), and the melting temperature (Tm). It can have at least one characteristic. Specifically, the first PHA and the second PHA can be distinguished according to the content of 4-HB repeating units, glass transition temperature (Tg), crystallization temperature (Tg), melting temperature (Tm), etc.

According to one embodiment of the present invention, the PHA may include the first PHA, or may include both the first PHA and the second PHA.

Specifically, the PHA includes a first PHA that is a semi-crystalline PHA, or includes both a first PHA that is a semi-crystalline PHA and a second PHA that is an amorphous PHA, and more specifically, the content of the first PHA and the second PHA. By controlling , the yield of the desired material can be more effectively controlled.

In addition, the glass transition temperature (Tg) of the PHA is -45°C to 80°C, -35°C to 80°C, -30°C to 80°C, -25°C to 75°C, -20°C to 70°C, -35°C. to 5℃, -25℃ to 5℃, -35℃ to 0℃, -25℃ to 0℃, -30℃ to -10℃, -35℃ to -15℃, -35℃ to -20℃, - It may be 20°C to 0°C, -15°C to 0°C, or -15°C to -5°C.

The crystallization temperature (Tc) of the PHA is not measured, or is 60°C to 120°C, 60°C to 110°C, 70°C to 120°C, 75°C to 120°C, 75°C to 115°C, 75°C to 110°C, or 90°C. It may be from ℃ to 110℃.

The melting temperature (Tm) of the PHA is not measured or is 100°C to 170°C, 105°C to 170°C, 105°C to 165°C, 110°C to 160°C, 115°C to 155°C, 110°C to 150°C, 120°C. It may be from ℃ to 150℃ or from 120℃ to 140℃.

Additionally, the weight average molecular weight of the PHA may be 10,000 g/mol to 1,200,000 g/mol. For example, the weight average molecular weight of the PHA is 50,000 g/mol to 1,200,000 g/mol, 100,000 g/mol to 1,000,000 g/mol, 200,000 g/mol to 1,200,000 g/mol, 250,000 g/mol to 1,150,000 g/mol. , 300,000 g/mol to 1,100,000 g/mol, 350,000 g/mol to 950,000 g/mol, 100,000 g/mol to 900,000 g/mol, 200,000 g/mol to 800,000 g/mol, 250,000 g/mol to 650,000 g/ mol , 200,000 g/mol to 400,000 g/mol, 300,000 g/mol to 600,000 g/mol, 500,000 g/mol to 1,200,000 g/mol, 500,000 g/mol to 1,000,000 g/mol 550,000 g/mol to 1,050,00 0 g/mol, It may be 550,000 g/mol to 900,000 g/mol, 600,000 g/mol to 900,000 g/mol or 500,000 g/mol to 900,000 g/mol.

The crystallinity of the PHA measured by differential scanning calorimeter (DSC) may be 90% or less. For example, the crystallinity of the PHA may be measured by differential scanning heat capacity analysis and may be 90% or less, 85% or less, 80% or less, 75% or less, or 70% or less.

Additionally, the average particle size of the PHA may be 0.5 ㎛ to 5 ㎛. For example, the average particle size of the PHA is 0.7 ㎛ to 4.6 ㎛, 1.1 ㎛ to 4.5 ㎛, 1.5 ㎛ to 4.3 ㎛, 2.2 ㎛ to 4.2 ㎛, 2.6 ㎛ to 4.0 ㎛, 2.8 ㎛ to 3.9 ㎛ or 3. .1 ㎛ to It may be 3.8 μm.

The average particle size of the PHA can be measured using a nano particle size analyzer (ex. Zetasizer Nano ZS). Specifically, for the PHA, the average particle size was measured using the principle of dynamic light scattering (DLS) at a temperature of 25°C and a measurement angle of 175° using Zetasizer Nano ZS (manufacturer: Marven). At this time, the peak value derived through the polydispersity index (PDI) at a confidence interval of 0.5 was measured as the particle size.

The polydispersity index (PDI) of the PHA may be less than 2.5. For example, the polydispersity index of the PHA may be less than 2.5, less than 2.3, less than 2.1, or less than 2.0.

Additionally, the PHA may be obtained by cell disruption using a non-mechanical method or a chemical method. Specifically, the PHA is a thermoplastic natural polyester polymer that accumulates in microbial cells and has a relatively large average particle size, so it was obtained through a crushing process to more effectively control the yield of the desired material and improve process efficiency. It may be.

In addition, the biodegradable aqueous dispersion may include 10% by weight to 80% by weight of the polyhydroxyalkanoate based on the total weight of the biodegradable aqueous dispersion composition. For example, the content of the PHA is 10% to 70% by weight, 12% to 60% by weight, 15% to 55% by weight, and 20% to 55% by weight based on the total weight of the biodegradable aqueous dispersion composition. %, 25% to 50% by weight, 30% to 45% by weight, or 35% to 45% by weight.

Cellulose Nanofibers/Carboxymethyl Cellulose

The biodegradable aqueous dispersion composition according to an embodiment of the present invention includes cellulose nanofibers (CNF) or carboxymethyl cellulose (CMC).

The biodegradable aqueous dispersion composition according to an embodiment of the present invention includes the cellulose nanofibers or carboxymethyl cellulose, and thus can effectively prevent agglomeration between components, especially polymers, from occurring during the manufacturing process, thereby improving viscosity properties, Acidity and storage stability can be further improved.

While PHA has excellent biodegradability and biocompatibility, the oil resistance and storage stability of dispersions containing it may be relatively low. Accordingly, the biodegradable aqueous dispersion composition according to an embodiment of the present invention is a cellulose nanofiber prepared to be suitable for the PHA, specifically for the PHA having the content range of the 4-HB repeating unit or specific physical properties as described above. , or by including carboxymethyl cellulose with specific physical properties, viscosity characteristics, dispersibility, and storage stability can be further improved.

In particular, the cellulose nanofibers and carboxymethyl cellulose are PHA containing 0.1% to 25% by weight of 4-HB repeating units, or when used together with PHA consisting only of the first PHA, which is a semi-crystalline PHA with controlled crystallinity. , viscosity properties, dispersibility and storage stability can be further improved.

More specifically, the repeating unit of 4-HB is 0.1% to 25% by weight, 0.2% to 22% by weight, 0.5% to 20% by weight, 1% to 18% by weight, and 2% to 16% by weight. , the cellulose nanofibers or By applying carboxymethyl cellulose, the viscosity properties, dispersibility and storage stability can be further improved, and by controlling the physical properties of the cellulose nanofibers and carboxymethyl cellulose, the improvement in viscosity properties, dispersibility and storage stability can be maximized. there is.

Additionally, the cellulose nanofibers and carboxymethyl cellulose may include hydrophilic functional groups. Oil resistance can be improved because the cellulose nanofibers and carboxymethyl cellulose contain a plurality of hydrophilic functional groups, and barrier properties can be further improved through strong hydrogen bonding during the drying process of the dispersion composition containing them.

More specifically, the cellulose nanofibers and carboxymethyl cellulose have a large number of hydrophilic groups and a high aspect ratio, so they can greatly contribute to improving viscosity, and create a Pickering emulsion and steric hindrance between PHA dispersion particles to form PHA particles. It can prevent agglomeration with each other. In addition, due to its high compatibility with PHA, it can prevent the aggregation of unstable dispersed PHA particles and play a role in enabling redispersion in the future. In addition, oil resistance can be greatly improved due to high hydrogen bonding when coating the prepared PHA dispersion.

In particular, the cellulose nanofibers may be cellulose nanofibers manufactured by pretreatment through processes such as enzyme treatment or oxidation treatment. More specifically, the cellulose nanofibers may include oxidized cellulose nanofibers, enzyme-treated and oxidized cellulose nanofibers, or microfibrillated cellulose. By including cellulose nanofibers pretreated with a specific catalyst, the compatibility with PHA having the above-mentioned characteristics is very excellent, and thus dispersibility, storage stability, coating properties, oil resistance, and processability can be further improved.

The characteristics of cellulose nanofibers and carboxymethyl cellulose suitable for the PHA will be described in detail below.

According to one embodiment of the present invention, the biodegradable aqueous dispersion composition may include cellulose nanofibers.

The cellulose nanofibers may include oxidized cellulose nanofibers, enzyme-treated and oxidized cellulose nanofibers, or microfibrillated cellulose.

The width of the cellulose nanofibers may be 100 nm or less. For example, the width of the cellulose nanofiber may be 80 nm or less, 50 nm or less, 30 nm or less, 25 nm or less, 20 nm or less, 13 nm or less, or 10 nm or less, 1 nm to 100 nm, 2 nm or less. 95 nm, 5 nm to 85 nm, 10 nm to 80 nm, 15 nm to 75 nm, 20 nm to 70 nm, 1 nm to 50 nm, 2 nm to 40 nm, 3 nm to 30 nm, 5 nm to 20 nm , 1 nm to 10 nm, 2 nm to 10 nm, or 5 nm to 10 nm.

Additionally, the length of the cellulose nanofibers may be 200 nm or more. For example, the length of the cellulose nanofiber may be 250 nm or more, 300 nm or more, 400 nm or more, 600 nm or more, 850 nm or more, or 1 μm or more.

The aspect ratio of the cellulose nanofibers may be 2 to 500. For example, the aspect ratio of the cellulose nanofibers may be 3 to 450, 10 to 400, or 20 to 350.

Additionally, the carboxyl group content of the cellulose nanofibers may be 0.01 mmol/g to 2.00 mmol/g. For example, the carboxyl group content of the cellulose nanofibers is 0.05 mmol/g to 2.00 mmol/g, 0.08 mmol/g to 1.80 mmol/g, 0.10 mmol/g to 1.75 mmol/g, 0.20 mmol/g to 1.60 mmol/ g or 0.30 mmol/g to 1.60 mmol/g.

Specifically, carboxyl groups can be introduced into cellulose nanofibers through pretreatment such as carboxymethylation, enzyme treatment, oxidation treatment, etc., and physical properties such as viscosity characteristics of cellulose nanofibers can be controlled depending on the content of the introduced carboxyl groups. When the carboxyl group content of cellulose nanofibers satisfies the above range, storage stability and redispersibility can be further improved.

The viscosity of the cellulose nanofibers may be 50 cps to 3,000 cps. For example, the viscosity of the cellulose nanofibers may be 100 cps to 2,500 cps, 150 cps to 2,000 cps, or 200 cps to 1,500 cps. When the viscosity of cellulose nanofibers satisfies the above range, not only the thickening effect but also storage stability can be further improved.

According to one embodiment of the present invention, the biodegradable aqueous dispersion composition may include carboxymethyl cellulose.

The carboxymethyl cellulose is obtained by carboxymethylating some of the hydroxyl groups of cellulose, and refers to a cellulose derivative to which a carboxymethyl group (-CH ₂ -COOH) is bonded.

Carboxymethyl cellulose can also improve oil resistance by containing multiple hydrophilic functional groups, and can further improve barrier properties through strong hydrogen bonding during the drying process of a dispersion composition containing it.

The width of the carboxymethyl cellulose may be 1,500 nm or less. For example, the width of the carboxymethyl cellulose may be 1,200 nm or less, 1,000 nm or less, or 800 nm or less, 30 nm to 1,500 nm, 40 nm to 1,200 nm, 50 nm to 1,000 nm, 80 nm to 1,000 nm, or 100 nm. It may be from nm to 800 nm.

Additionally, the length of the carboxymethyl cellulose may be 800 nm or more. For example, the length of the carboxymethyl cellulose may be 900 nm or more, 1,000 nm or more, 1,200 nm or more, or 1,500 nm or more.

The aspect ratio of the carboxymethyl cellulose may be 2 to 500. For example, the aspect ratio of the carboxymethyl cellulose may be 3 to 450, 10 to 400, or 20 to 350.

The carboxymethyl group content of the carboxymethyl cellulose may be 3.00 mmol/g to 8.00 mmol/g. For example, the carboxymethyl group content of the carboxymethyl cellulose is 3.25 mmol/g to 7.50 mmol/g, 3.50 mmol/g to 7.15 mmol/g, 3.70 mmol/g to 7.00 mmol/g, 4.00 mmol/g to 6.50 mmol. /g, 4.50 mmol/g to 6.15 mmol/g or 4.65 mmol/g to 6.00 mmol/g. When the carboxymethyl group content of carboxymethyl cellulose satisfies the above range, storage stability and redispersibility can be further improved.

The viscosity of the carboxymethyl cellulose may be 2,000 cps to 5,000 cps. For example, the viscosity of the carboxymethyl cellulose may be 2,200 cps to 4,800 cps, 2,500 cps to 4,500 cps, 2,800 cps to 4,300 cps, or 3,000 cps to 4,000 cps. When the viscosity of carboxymethyl cellulose satisfies the above range, not only the thickening effect but also storage stability can be further improved.

Additionally, the biodegradable aqueous dispersion composition may include 0.01% by weight or more of the cellulose nanofibers or carboxymethyl cellulose based on the total weight of the biodegradable aqueous dispersion composition. For example, the content of the cellulose nanofibers or carboxymethyl cellulose is 0.02% by weight or more, 0.05% by weight or more, 0.08% by weight or more, 0.1% by weight or more, 0.12% by weight or more based on the total weight of the biodegradable aqueous dispersion composition. , may be 0.15% by weight or more, 0.3% by weight or more, 0.5% by weight or more, or 1% by weight or more, and may be 0.01% to 10% by weight, 0.01% to 8% by weight, 0.02% to 6% by weight, 0.05% by weight. It may be from 4% by weight, 0.1% to 3% by weight, 0.15% to 2% by weight, 0.2% to 1.5% by weight, or 0.25% to 1.2% by weight.

dispersant

The biodegradable aqueous dispersion according to an embodiment of the present invention may include a dispersant.

Specifically, the dispersant may be one or more selected from the group consisting of phosphoric acid-based dispersants, fatty acid-based dispersants, acrylic-based dispersants, urethane-based dispersants, and epoxy-based dispersants, and one type selected from the group consisting of carboxylic acids, amines, isocyanates, and derivatives thereof. It may be a polymer dispersant containing the above.

More specifically, the dispersant is polyacrylate-based, polyvinyl alcohol, polyvinylpyrrolidone, methylpolyethylene alkyl ether, sodium dodecylbenzene sulfonate, alkylbenzene sulfonate, nonylphenol ether sulfate, sodium lauryl sulfate, and lithium. It may include one or more selected from the group consisting of dodecyl sulfate, alkyl phosphate, and polypropylene glycol ester.

According to another embodiment of the present invention, the dispersant may be polyvinyl alcohol.

Polyvinyl alcohol can be obtained by polymerizing polyvinyl acetate (PVAc) and then substituting the hydrophobic CH ₃ COO- with the hydrophilic -OH through a hydrolysis reaction, where -OH is substituted for the total amount. The degree, that is, the ratio of CH ₃ COO- and -OH, is the degree of saponification. That is, the degree of saponification may vary depending on the molecular weight or distribution characteristics of polyvinyl alcohol during the -OH substitution reaction, and may affect the final resin physical properties.

Specifically, the degree of saponification of the polyvinyl alcohol may be 80 mol% to 98 mol%. For example, the degree of saponification of the polyvinyl alcohol may be 82 mol% to 98 mol% or 85 mol% to 98 mol%.

When the degree of saponification of polyvinyl alcohol satisfies the above range, dispersibility and storage stability can be improved, and an appropriate viscosity for coating can be obtained, thereby improving coating properties, productivity, and processability. Specifically, if the degree of saponification is outside the above range, the solubility or dispersibility of the dispersant may be greatly reduced, making it impossible to form a coating layer using a biodegradable aqueous dispersion composition.

Additionally, the average degree of polymerization of the polyvinyl alcohol may be 200 or less. For example, the average degree of polymerization of the polyvinyl alcohol may be 180 or less or 150 or less, and may be 80 to 200, 90 to 200, or 100 to 200. When the degree of polymerization of polyvinyl alcohol satisfies the above range, dispersibility, storage stability, coating properties, water resistance, and processability can be improved without deteriorating mechanical properties.

When the saponification degree and polymerization degree of polyvinyl alcohol both satisfy the above range, dispersibility, storage stability, coating properties, water resistance, and processability can all be improved. In particular, polyvinyl alcohol with a degree of saponification and polymerization that satisfies the above range has excellent compatibility with PHA, which has the above-mentioned characteristics, and can maximize improvements in dispersibility, storage stability, coating properties, water resistance, and processability. there is.

The biodegradable aqueous dispersion composition may include 0.01% by weight to 30% by weight of the dispersant based on the total weight of the biodegradable aqueous dispersion composition. For example, the content of the dispersant is 0.01% by weight to 20% by weight, 0.01% by weight to 15% by weight, 0.01% by weight to 12% by weight, and 0.02% by weight to 8% by weight based on the total weight of the biodegradable aqueous dispersion. , 0.05% to 6% by weight, 0.1% to 5% by weight, 0.2% to 3% by weight, 0.3% to 3.5% by weight, 0.5% to 2% by weight or 0.8% to 1.2% by weight. there is.

Method for producing biodegradable aqueous dispersion composition

A method for producing a biodegradable aqueous dispersion composition according to another embodiment of the present invention includes obtaining a polyhydroxyalkanoate suspension; And mixing and stirring the polyhydroxyalkanoate suspension and cellulose nanofibers or carboxymethyl cellulose.

Obtaining polyhydroxyalkanoate suspension

A method for producing a biodegradable aqueous dispersion composition according to another embodiment of the present invention includes obtaining a polyhydroxyalkanoate suspension.

Specifically, the polyhydroxyalkanoate suspension can be obtained by mixing and stirring polyhydroxyalkanoate, a dispersant, and water.

The description of the polyhydroxyalkanoate and dispersant is the same as above.

Additionally, according to another embodiment of the present invention, a solvent may be additionally added to the mixture of the polyhydroxyalkanoate, dispersant, and water.

Specifically, the solvent may be water or a mixture of distilled water and a hydrophilic solvent. For example, the hydrophilic solvent is methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol, tert-amyl It may be one or more selected from the group consisting of alcohol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol, and cyclohexanol.

The stirring may be performed at 1,500 rpm to 13,000 rpm for 1 minute to 60 minutes. For example, the stirring may be performed with a high-speed homogenizing disper, at 2,500 rpm to 12,000 rpm, 4,000 rpm to 10,000 rpm, 4,500 rpm to 9,500 rpm, 5,500 rpm to 9,000 rpm, or 6,000 rpm to 8,000 rpm. It may be performed for 1 minute to 35 minutes, 2 minutes to 20 minutes, or 3 minutes to 10 minutes. When the stirring process conditions satisfy the above range, dispersibility, storage stability, coating properties, and processability can be further improved.

Mixing and stirring the polyhydroxyalkanoate suspension and cellulose nanofibers or carboxymethyl cellulose

A method for producing a biodegradable aqueous dispersion composition according to another embodiment of the present invention includes mixing and stirring the polyhydroxyalkanoate suspension and cellulose nanofibers or carboxymethyl cellulose.

The cellulose nanofibers may include oxidized cellulose nanofibers, enzyme-treated and oxidized cellulose nanofibers, or microfibrillated cellulose.

The description of the cellulose nanofibers or carboxymethyl cellulose is the same as above.

Additionally, the stirring may be performed at 1,500 rpm to 13,000 rpm for 1 minute to 60 minutes. For example, the stirring may be performed with a homomixer, at 2,500 rpm to 12,000 rpm, 4,000 rpm to 10,000 rpm, 4,500 rpm to 9,500 rpm, 5,500 rpm to 9,000 rpm, or 6,000 rpm to 8,000 rpm for 1 minute to 50 minutes. , may be performed for 2 minutes to 40 minutes, 5 minutes to 35 minutes, 10 minutes to 35 minutes, or 15 minutes to 30 minutes. When the stirring process conditions satisfy the above range, dispersibility, storage stability, coating properties, and processability can be further improved.

Manufacturing method of cellulose nanofibers

A method for producing cellulose nanofibers according to another embodiment of the present invention includes the steps of (1) adjusting the pH of biomass containing cellulose to 3.5 to 6.5; (2) enzymatic treatment by adding enzyme and reacting at 35°C or higher; and (3) oxidation treatment.

Step (1) - pH adjustment step

A method for producing cellulose nanofibers according to another embodiment of the present invention includes adjusting the pH of biomass containing cellulose to 3.5 to 6.5.

Specifically, in the pH adjustment step, the pH of the biomass containing cellulose is adjusted to 3.5 to 6.5, 3.6 to 6.3, 3.8 to 6.2, 4.0 to 6.0, or 4.5 to 5.5 using a sodium acetate buffer. . By adjusting the pH of the biomass containing the cellulose to the above range, the enzyme introduced later can be further activated, thereby maximizing the effect of the enzyme treatment.

Step (2) - Enzyme treatment step

A method for producing cellulose nanofibers according to another embodiment of the present invention includes the step of enzymatic treatment by adding enzymes and reacting at a temperature of 35°C or higher.

Specifically, in step (2), the enzyme may be added in an amount of 100 unit/g to 500 unit/g. For example, the dosage of enzyme is 120 unit/g to 480 unit/g, 150 unit/g to 450 unit/g, 200 unit/g to 400 unit/g, 220 unit/g to 360 unit/g or 250 unit. /g to 350 unit/g. When the amount of enzyme input satisfies the above range, the effect of enzyme treatment can be further improved.

The enzyme may include one or more selected from the group consisting of xylanase, mannanase, endoglucanase, and exoglucanase.

According to another embodiment of the present invention, step (2) is a step of enzymatic treatment by adding an enzyme and performing a primary reaction at a temperature of 35 ℃ to 60 ℃, raising the temperature to 65 ℃ or more and performing a secondary reaction. You can. Through the secondary reaction, the reaction can be terminated by controlling or inhibiting the activity of the enzyme.

Specifically, the first reaction may be performed at 38°C to 58°C, 40°C to 55°C, 42°C to 53°C, or 45°C to 52°C, and the secondary reaction may be performed at 68°C or higher, 70°C or higher, It may be performed by raising the temperature to 75°C or higher, 76°C or higher, or 80°C or higher. When the process temperature of the first reaction and the second reaction satisfies the above range, the activation of the enzyme can be improved and the effect of the enzyme treatment can be maximized.

Additionally, the first reaction may be performed at 50 rpm to 1,000 rpm for 10 to 100 minutes, and the second reaction may be performed for 5 to 70 minutes. For example, the first reaction and the second reaction may be performed through a glass reactor or an extruder, and the first reaction is performed at 55 rpm to 850 rpm, 60 rpm to 500 rpm, 80 rpm to 400 rpm, and 100 rpm. to 250 rpm or 120 rpm to 180 rpm for 20 minutes to 95 minutes, 35 minutes to 80 minutes, 40 minutes to 75 minutes, 50 minutes to 70 minutes, or 55 minutes to 65 minutes, and the secondary reaction is It may be performed for 10 to 60 minutes, 15 to 55 minutes, 20 to 40 minutes, or 25 to 35 minutes.

Step (3) - Oxidation treatment step

A method for producing cellulose nanofibers according to another embodiment of the present invention includes the step of oxidation treatment. Specifically, the oxidation treatment step may be performed using an oxidizing agent. For example, the oxidation treatment step may be performed by adding at least one oxidizing agent selected from the group consisting of NaClO, NaClO ₂ , H ₂ O ₂ and O ₃ to the enzyme-treated cellulose nanofibers.

In the oxidation treatment step, the oxidizing agent may be added in an amount of 1 mmol/g to 30 mmol/g. For example, the content of the oxidizing agent is 2 mmol/g to 20 mmol/g, 3 mmol/g to 16 mmol/g, or 4 mmol/g to 12 mmol/g based on the total weight of the enzyme-treated cellulose nanofibers. It can be.

Additionally, the oxidation treatment step may be performed at room temperature (25°C) for 1 hour to 6 hours, 1 hour to 5 hours, 1.5 hours to 4.5 hours, or 2 hours to 4 hours. For example, the oxidation treatment step may be performed by adding an oxidizing agent and maintaining the pH at 10.5 or higher using NaOH at room temperature.

Additionally, in the oxidation treatment step, additives may be added in an amount of 0.01 mmol/g to 20 mmol/g. For example, the content of the additive is 0.02 mmol/g to 18 mmol/g, 0.05 mmol/g to 16 mmol/g, 0.1 mmol/g to 10 mmol/g, 0.1 mmol/g to 6 mmol/g, 0.15 mmol/g to 10 mmol/g. mmol/g to 4 mmol/g, 0.01 mmol/g to 2 mmol/g, 0.03 mmol/g to 1.8 mmol/g, 0.06 mmol/g to 1.4 mmol/g, 0.08 mmol/g to 1.2 mmol/g or 0.1 It may be mmol/g to 1.0 mmol/g.

The additive may include one or more selected from the group consisting of catalysts and pH adjusters.

Specifically, the catalyst may include one or more selected from the group consisting of 2,2,6,6-tetraalkylpiperidine-1-oxyl (TEMPO), NaBr, KBr, and HBr. Additionally, the pH adjuster may include one or more selected from the group consisting of HCl, citric acid, and NaOH.

Step (4) - Washing Step

A method for producing cellulose nanofibers according to another embodiment of the present invention may include washing at 2,500 rpm to 15,000 rpm for 1 to 30 minutes after the oxidation treatment step.

For example, the oxidized cellulose nanofibers are centrifuged at 3,000 rpm to 12,000 rpm, 3,500 rpm to 10,000 rpm, or 4,000 rpm to 9,000 rpm for 1 minute to 20 minutes, 2 minutes to 15 minutes, or 3 minutes to 3 minutes. The washing step can be performed for 10 minutes. Additionally, the washing step may be performed 1 to 10 times, 2 to 8 times, 3 to 6 times, or 4 to 5 times.

Step (5) - Distributed processing step

A method for producing cellulose nanofibers according to another embodiment of the present invention may include the step of dispersing 1 to 10 times at 50 bar to 1,500 bar after the washing step.

For example, the washed cellulose nanofibers are processed once to eight times at 60 bar to 800 bar, 100 bar to 600 bar, 150 bar to 550 bar, 200 bar to 500 bar, or 250 bar to 400 bar using a high pressure homogenizer. It can be dispersed once, 1 to 6 times, or 2 to 5 times.

biodegradable items

A biodegradable article according to another embodiment of the present invention includes a substrate; and a biodegradable coating layer on at least one side of the substrate, wherein the biodegradable coating layer includes polyhydroxyalkanoate, cellulose nanofibers or carboxymethyl cellulose, and water.

The description of the polyhydroxyalkanoate, cellulose nanofibers, and carboxymethyl cellulose is the same as above.

The substrate is not limited as long as it is an article that can form a biodegradable coating layer on the surface of the substrate. For example, the substrate may include paper, kraft paper, fabric, non-woven fabric, polyethylene terephthalate (PET) film, polybutylene succinate (PBS), polybutylene adipate (PBA), polybutylene adipate terephthalate ( It may be one or more types selected from the group consisting of polyester-based films such as PBAT), polybutylene succinate terephthalate (PBST), and polyimide (PI) films.

Specifically, it may be preferable that the substrate is a single material in terms of improving the coating properties of the substrate, and the substrate may be paper, kraft paper, fabric, or non-woven fabric, but is not limited thereto. Additionally, when the substrate includes paper or kraft paper, it has better biodegradability than other plastic materials, making it more advantageous to provide eco-friendly packaging materials.

The thickness of the substrate may be 15 μm or more. For example, the thickness of the substrate may be 15 μm or more, 20 μm or more, 50 μm or more, 70 μm or more, 100 μm or more, 130 μm or more, 150 μm or more, 200 μm or more, 300 μm or more, or 500 μm or more. .

Additionally, the basis weight of the substrate may be 30 g/m ² to 500 g/m ² . For example, the substrate may be paper, kraft paper, fabric, knitted fabric, or non-woven fabric, and the basis weight of the substrate is 30 g/m ² to 500 g/m ² , 30 g/m ² to 350 g/m ² , 30 g/m ² to 200 g/m ² , 50 g/m ² to 200 g/m ² , 80 g/m ² to 200 g/m ² , 100 g/m ² to 200 g/m ² , 130 g /m ² to 190 g/m ² , 150 g/m ² to 185 g/m ² or 120 g/m ² to 320 g/m ² .

Meanwhile, a barrier layer may be disposed on at least one side of the substrate, and an eco-friendly barrier film may be coated on the surface of the substrate to have moisture and/or oxygen barrier properties, or a functional coating layer with antistatic performance or adhesive performance may be applied. Additional information may be included. The functional coating layer may include a primer coating layer and an adhesive coating layer, and these may have commonly used materials and physical properties as long as they do not impair the desired effect of the present invention.

Additionally, the thickness of the biodegradable coating layer may be 5 ㎛ to 50 ㎛, 5 ㎛ to 40 ㎛, or 6 ㎛ to 30 ㎛.

The biodegradable article may have a kit rating of 5 or higher as measured by TAPPI UM 557. For example, the kit rating may be 4 or higher, 5 or higher, or 6 or higher. As the kit grade of the biodegradable product satisfies the above range, it has excellent oil resistance.

Specifically, the kit grade can be measured through an oil resistance kit grade test according to TAPPI UM 557 "Repellency of Paper and Board to Grease, Oil, and Waxes (Kit Test)".

More specifically, the kit grade number test reagent is dropped from a certain height on the surface of the biodegradable article (width 5 cm and length 15 cm), that is, on the coating layer formed on the biodegradable article. Then, after a certain period of time has elapsed, the oil resistance kit grade can be measured by wiping off the excess kit grade test reagent with a clean tissue or cotton swatch and immediately visually inspecting the surface.

In the above inspection, if it darkens significantly compared to the surface on which the test reagent was not dropped, it is checked as failed, and if not, it is checked as pass. As described above, experiments are repeated with test reagents of increasingly higher kit grades until a failing kit grade test reagent is found, and the oil resistance kit grade can be measured as the average of the highest passing kit grade reagents.

The biodegradable article including the biodegradable coating layer may be, but is not limited to, packaging materials, cardboard boxes, shopping bags, disposable tableware, packaging containers, or paper straws.

Method for manufacturing biodegradable articles

A method for producing a biodegradable article according to another embodiment of the present invention includes preparing a biodegradable aqueous dispersion composition; and forming a biodegradable coating layer on at least one side of the substrate using the biodegradable aqueous dispersion composition.

The method for preparing the biodegradable aqueous dispersion is as described above, and the description of the substrate is also as described above.

The step of forming the biodegradable coating layer may be performed by applying the biodegradable aqueous dispersion composition to at least one surface of the substrate and drying it.

Specifically, the application amount of the biodegradable aqueous dispersion composition applied to at least one side of the substrate is 5 g/m ² to 100 g/m ² , 5 g/m ² to 85 g/m ² , and 5 g/m ² to 70 g/m ² , 8 g/m ² to 60 g/m ² , 9 g/m ² to 50 g/m ² , 5 g/m ² to 50 g/m ² , 6 g/m ² to 40 g /m ² , 7 g/m ² to 30 g/m ² or 10 g/m ² to 40 g/m ² . When the application amount satisfies the above range, coating properties, productivity, and processability can be further improved.

Additionally, the application may be performed once to form a single coating layer, or may be performed twice or more to form a plurality of coating layers. The application amount can be adjusted within the above range depending on the desired number of coating layers. Specifically, the application amount may be the total amount applied to a plurality of coating layers.

After the biodegradable aqueous dispersion composition is applied on a substrate, it may be dried at 100°C to 200°C for 5 seconds to 30 minutes. For example, the drying is performed at 100°C to 200°C, 110°C to 185°C, 120°C to 180°C, or 130°C to 175°C for 5 seconds to 30 minutes, 10 seconds to 25 minutes, 20 seconds to 20 minutes, 30 minutes. It may be performed for seconds to 15 minutes or 40 seconds to 10 minutes.

The step of forming the biodegradable coating layer can be applied without particular limitations as long as it is a coating process commonly used in the art. For example, the step of forming the biodegradable coating layer may be performed by gravure coating, throat coating, doctor blade coating, spray coating, bar coating, spin coating, or inline coating, but is not limited thereto.

The above will be explained in more detail by the following examples. However, the following examples are only for illustrating the present invention, and the scope of the examples is not limited to these only.

[Example]

Preparation of cellulose nanofibers

Preparation Example 1-1: Microfibrillated cellulose

Inject 2 L of a suspension containing 2% by weight of softwood pulp dispersed in water (Product name: SWP, Manufacturer: Ssangyong C&B) into a grinder (Product name: MKCA6-5, Manufacturer: Masuko, Grinding stone spacing: -150 ㎛) and grind 30 times at 1,500 rpm. It was pulverized and dispersed twice at 1,000 bar and five times at 1,500 bar using a high-pressure homogenizer (Product name: Atomo 3.0, Manufacturer: BERTOLI) to produce microfibrillated cellulose (MFC, width: 20 nm to 70 nm). , length: 1 ㎛ or more) were prepared.

Preparation Example 1-2: Enzyme-treated and oxidized cellulose nanofibers

The pH of the 25% by weight hydrated coniferous cake (product name: SWP, manufacturer: Ssangyong C&B) was adjusted to 5.0 using sodium acetate buffer. Afterwards, 300 units/g of endoglucanase as an enzyme was added, and a kneader reactor (product name: Kneader, manufacturer: Changseong P&R) was used to react at 50°C under conditions of 20% to 30% by weight of pulp. After the primary reaction was performed at 150 rpm for 1 hour, the temperature was raised to 80°C and the secondary reaction was performed for 30 minutes to perform enzyme treatment.

Afterwards, distilled water was added to adjust the concentration to 3% by weight to 5% by weight, and then 2,2,6,6-tetraalkylpiperidine-1-oxyl (TEMPO) catalyst (product name: TEMPO, manufacturer: J&H chemical) ) 0.1 mmol/g, NaBr catalyst (product name: sodium bromide, manufacturer: Sigma-aldrich) 1.0 mmol/g and oxidizing agent (NaClO, product name: Sodium hydroxide, manufacturer: JUNSEI) 5.0 mmol/g were added and pH was adjusted using NaOH. Oxidation was performed at room temperature (25°C) while maintaining 10.5 or higher.

Afterwards, it was washed for 5 minutes at 9,000 rpm using a centrifuge (product name: CR22N, manufacturer: Himac), the concentration was adjusted to 3% by weight to 5% by weight, and the concentration was adjusted to 3% by weight to 5% by weight, followed by a high-pressure homogenizer (product name: ATOMI 3.0, manufacturer: Enzyme-treated and oxidized cellulose nanofibers (TOCN, width: 10 nm or less, length: 200 nm or more) were prepared by dispersing 2 to 5 times at 300 bar using BERTOLI).

Preparation Example 1-3: Oxidized cellulose nanofibers

Softwood pulp (Product name: SWP, Manufacturer: Ssangyong C&B) was adjusted to 2% by weight and then dissociated by processing at 3,000 revolutions using a disintegrator (Product name: disintegrator, Manufacturer: Daeil Machinery).

Afterwards, distilled water was added to the prepared pulp cake after water filtration using a Buchner funnel to adjust the concentration to 3% by weight to 5% by weight, and then 2,2,6,6-tetraalkylpiperidine-1- Oxyl (TEMPO) catalyst (Product name: TEMPO, Manufacturer: J&H chemical) 0.1 mmol/g, NaBr catalyst (Product name: sodium bromide, Manufacturer: Sigma-aldrich) 1.0 mmol/g and oxidizing agent (NaClO, Product name: Sodium hydroxide, Manufacturer: JUNSEI) 10.0 mmol/g was added and oxidation was performed at room temperature (25°C) while maintaining pH above 10.5 using NaOH.

Afterwards, it was washed for 5 minutes at 9,000 rpm using a centrifuge (product name: CR22N, manufacturer: Himac), the concentration was adjusted to 3% by weight to 5% by weight, and the concentration was adjusted to 3% by weight to 5% by weight, followed by a high-pressure homogenizer (product name: ATOMI 3.0, manufacturer: Oxidized cellulose nanofibers (TOCN, width: 10 nm or less, length: 200 nm or more) were prepared by dispersing 2 to 5 times at 300 bar using BERTOLI).

Preparation of biodegradable aqueous dispersion compositions

Example 2-1

(1) PHA preparation step

Polyhydroxyalkanoate (PHA) (weight average molecular weight (Mw): 340,000 g/mol, polydispersity index (PDI): 2.6, average particle size: 12.5 ㎛, content of 4-hydroxybutyrate (4-HB) : 10% by weight, manufacturer: CJ) Powder was prepared.

(2) Preparation of biodegradable aqueous dispersion composition

40 parts by weight of the PHA powder prepared in step (1), 10 parts by weight of 10% concentration polyvinyl alcohol (PVA, degree of saponification: 80 mol%, average degree of polymerization: 13,000), manufacturer: kuraray), and 58.7 parts by weight of distilled water. It was added to a homogenizing disper (product name: homogenizing disper manufacturer: PRIMIX) and mixed and stirred for 5 minutes at 6,000 rpm to 8,000 rpm to obtain a suspension.

Afterwards, 0.3 parts by weight of the microfibrillated cellulose prepared in Preparation Example 1-1 was added to the suspension, added to a homogenizing mixer (product name: homogenizing mixer, manufacturer: PRIMIX), and mixed at 6,000 rpm to 8,000 rpm for 30 minutes. and stirring to prepare a biodegradable aqueous dispersion composition having a solid content of 40.3% by weight.

Example 2-2

The above example, except that in step (2), 1.0 parts by weight of the enzyme-treated and oxidized cellulose nanofibers prepared in Preparation Example 1-2 were added instead of the microfibrillated cellulose prepared in Preparation Example 1-1. A biodegradable aqueous dispersion composition with a solid content of 40.3% by weight was prepared in the same manner as in 2-1.

Example 2-3

Example 2-1, except that in step (2), 1.0 parts by weight of the oxidized cellulose nanofibers prepared in Preparation Example 1-3 were added instead of the microfibrillated cellulose prepared in Preparation Example 1-1. A biodegradable aqueous dispersion composition with a solid content of 40.3% by weight was prepared in the same manner as above.

Example 2-4

In step (2), carboxymethyl cellulose (CMC, carboxymethyl group content: 5.0 mmol/g to 6.0 mmol/g, viscosity: 3,000 cps to 4,000 cps) was used instead of the microfibrillated cellulose prepared in Preparation Example 1-1. A biodegradable aqueous dispersion composition having a solid content of 40.3% by weight was prepared in the same manner as Example 2-1, except that it was added in parts by weight.

Comparative Example 2-1

In step (2), a biodegradable aqueous dispersion composition having a solid content of 40% by weight was prepared in the same manner as in Example 2-1, except that the microfibrillated cellulose prepared in Preparation Example 1-1 was not used. Manufactured.

Comparative Example 2-2

40 in the same manner as in Example 2-1, except that in step (2), microcrystalline cellulose (manufacturer: Sigma Aldrich) was used instead of the microfibrillated cellulose prepared in Preparation Example 1-1. A biodegradable aqueous dispersion composition with a solids content of % by weight was prepared.

[Experimental example]

Experimental Example 1: Storage stability

Storage stability of the biodegradable aqueous dispersion compositions prepared in Examples 2-1 to 2-4, Comparative Examples 2-1, and Comparative Examples 2-2 when heated in an oven at 50°C for 1 or 2 weeks was tested.

Specifically, the biodegradable aqueous dispersion composition was heated in an oven at 50°C for 1 or 2 weeks, and shear stress was applied at 3,200 rpm using a vortex mixer (product name: SI-0246A, manufacturer: scientific industries). After application, the degree of agglomeration and precipitation of the composition was visually checked when the bottom surface was scraped using a spoon, and the storage stability was evaluated according to the following evaluation criteria.

○: Little agglomeration or precipitation occurs.

×: Both agglomeration and precipitation occur.

Experimental Example 2: Viscosity

For the biodegradable aqueous dispersion compositions prepared in Examples 2-1 to 2-4, Comparative Examples 2-1, and Comparative Examples 2-2, a DVE-RV viscometer (manufacturer: Brook) was used to measure viscosity using shear stress. Viscosity was measured using a #63 spindle at 23°C using a field) at a shear rate of 12 rpm.

Experimental Example 3: Kit grade test

For the biodegradable aqueous dispersion compositions prepared in Examples 2-1 to 2-4, Comparative Examples 2-1, and Comparative Examples 2-2, TAPPI UM 557 "Repellency of Paper and Board to Grease, Oil, and Waxes ( An oil resistance kit grade test was conducted according to "Kit Test".

Specifically, the biodegradable aqueous dispersion composition was applied on a substrate using a bar coater (manufacturer: RDS) at an application rate of 25 g/m ² and dried at 170°C for 10 minutes to form a biodegradable coating layer. The formed biodegradable article was prepared. At this time, the substrate was uncoated kraft paper (manufacturer: Hansol Paper) with a basis weight of 180 g/m ² .

Five drops of the kit grade test reagent were dropped from a height of 2.54 cm on the surface of the biodegradable article (width 5 cm and length 15 cm), more specifically on the coating layer formed on one side of the biodegradable article. After 15 seconds had elapsed, excess kit grade water test reagent was wiped away with a clean tissue or cotton swatch and the surface was immediately assessed visually.

If it darkened significantly compared to the surface of the coating layer on which the test reagent was not dropped, it was checked as failed, and if not, it was checked as pass. As described above, the experiment was repeated with test reagents of increasingly higher kit grades until a test reagent with a failing kit grade was found, and the average value of the highest kit grade reagent that was checked as passing was evaluated as the oil resistance kit grade value. .

As shown in Table 1, the biodegradable products of Examples 2-1 to 2-4 had superior oil resistance and storage stability compared to Comparative Examples 2-1 and 2-2.

Specifically, since the biodegradable aqueous dispersions of Examples 1-1 to 1-4 have excellent viscosity characteristics, dispersibility, and storage stability, Examples 2-1 to 2-4 including a biodegradable coating layer prepared using them. The oil resistance and storage stability of the biodegradable product were excellent. In particular, the biodegradable product of Example 2-1 had excellent oil resistance, with kit grade 5 or higher. Therefore, when a biodegradable article containing a coating layer prepared using the biodegradable aqueous dispersion of the present invention is applied to articles requiring oil resistance, such as food packaging materials for packaging oily foods, it can exhibit excellent properties. .

Claims (19)

polyhydroxyalkanoate;
Cellulose nanofibers or carboxymethyl cellulose; and
contains water,
A biodegradable aqueous dispersion composition that does not cause agglomeration or precipitation when heated to a temperature of 50°C for one week and then redispersed with a mixer. According to claim 1,
When the biodegradable aqueous dispersion composition is heated at a temperature of 50°C for 2 weeks and then redispersed with a mixer, no agglomeration or precipitation occurs,
A biodegradable aqueous dispersion composition having an oil resistance kit rating of 4 or higher as measured according to TAPPI UM 557. According to claim 1,
A biodegradable aqueous dispersion composition wherein the cellulose nanofibers include oxidized cellulose nanofibers, enzyme-treated and oxidized cellulose nanofibers, or microfibrillated cellulose. According to claim 1,
The cellulose nanofibers are biodegradable, have a width of 100 nm or less, a length of 200 nm or more, an aspect ratio of 2 to 500, a carboxyl group content of 0.01 mmol/g to 2.00 mmol/g, and a viscosity of 50 cps to 3,000 cps. Aqueous dispersion composition. According to claim 1,
The carboxymethyl cellulose has a width of 1,500 nm or less, a length of 800 nm or more, an aspect ratio of 2 to 500, a carboxymethyl group content of 3.00 mmol/g to 8.00 mmol/g, and a viscosity of 2,000 cps to 5,000 cps, Biodegradable aqueous dispersion composition. According to claim 1,
A biodegradable aqueous dispersion composition comprising 0.01% by weight or more of the cellulose nanofibers or carboxymethyl cellulose based on the total weight of the biodegradable aqueous dispersion composition. According to claim 1,
The polyhydroxyalkanoate is 3-hydroxybutyrate (3-HB), 4-hydroxybutyrate (4-HB), 3-hydroxypropionate (3-HP), and 3-hydroxyhexanoate. (3-HH), 3-hydroxyvalerate (3-HV), 4-hydroxyvalerate (4-HV), 5-hydroxyvalerate (5-HV) and 6-hydroxyhexanoate ( 6-HH) A biodegradable aqueous dispersion composition, which is a polyhydroxyalkanoate copolymer comprising at least one repeating unit selected from the group consisting of According to claim 7,
The polyhydroxyalkanoate is a polyhydroxyalkanoate copolymer comprising a 4-hydroxybutyrate (4-HB) repeating unit and a 3-hydroxybutyrate (3-HB) repeating unit, wherein the 4-hydroxyalkanoate A biodegradable aqueous dispersion composition comprising 0.1% to 60% by weight of oxybutyrate (4-HB) repeating unit. According to claim 7,
The polyhydroxyalkanoate comprises a first PHA,
The first PHA contains 0.1% to 30% by weight of 4-hydroxybutyrate (4-HB) repeating units, has a glass transition temperature (Tg) of -30°C to 80°C, and a crystallization temperature (Tc) is 70°C to 120°C, and the melting temperature (Tm) is 105°C to 165°C. According to claim 1,
A biodegradable aqueous dispersion composition comprising 10% to 80% by weight of the polyhydroxyalkanoate based on the total weight of the biodegradable aqueous dispersion composition. According to claim 1,
The biodegradable aqueous dispersion composition includes a dispersant,
A biodegradable aqueous dispersion composition in which the content of the dispersant is 0.01% by weight to 30% by weight based on the total weight of the biodegradable aqueous dispersion composition. Obtaining a polyhydroxyalkanoate suspension; and
A method for producing a biodegradable aqueous dispersion composition comprising mixing and stirring the polyhydroxyalkanoate suspension and cellulose nanofibers or carboxymethyl cellulose. According to claim 12,
A method for producing a biodegradable aqueous dispersion composition, wherein the polyhydroxyalkanoate suspension is obtained by mixing and stirring polyhydroxyalkanoate, a dispersant, and water. According to claim 12,
A method for producing a biodegradable aqueous dispersion composition, wherein the cellulose nanofibers include oxidized cellulose nanofibers, enzyme-treated and oxidized cellulose nanofibers, or microfibrillated cellulose. (1) adjusting the pH of biomass containing cellulose to 3.5 to 6.5;
(2) enzymatic treatment by adding enzyme and reacting at a temperature of 35°C or higher; and
(3) A method for producing cellulose nanofibers, including the step of oxidation treatment. According to claim 15,
The method of producing cellulose nanofibers in which step (2) is a step of adding an enzyme and performing a primary reaction at a temperature of 35°C to 60°C, raising the temperature to 65°C or higher, and then performing a secondary reaction and enzymatic treatment. According to claim 15,
In step (2), the enzyme is added in an amount of 100 unit/g to 500 unit/g,
The enzyme is a method of producing cellulose nanofibers, including at least one selected from the group consisting of xylanase, mannanase, endoglucanase, and exoglucanase. According to claim 15,
A method for producing cellulose nanofibers, wherein step (3) is performed by adding at least one oxidizing agent selected from the group consisting of NaClO, NaClO ₂ , H ₂ O ₂ and O ₃ . According to claim 18,
In step (3), the additive is added in an amount of 0.01 mmol/g to 20 mmol/g,
The additive includes a catalyst,
The catalyst is a method of producing cellulose nanofibers, including one or more selected from the group consisting of 2,2,6,6-tetraalkylpiperidine-1-oxyl (TEMPO), NaBr, KBr, and HBr.