KR20220132828A - Manufacturing method of anionic water-dispersible polyurethane dispersion and biodegradable polyurethane film prepared therefrom - Google Patents

Abstract

The present invention relates to a method for preparing an anionic water-dispersible polyurethane dispersion and a biodegradable polyurethane film prepared from the dispersion. The method for preparing an anionic water-dispersible polyurethane dispersion comprises: a raw material mixing step of stirring isophorone diisocyanate dropwise while stirring castor oil and dimethylolbutanoic acid; a urethane synthesis step of mixing and synthesizing acetone in a mixture prepared through the raw material mixing step; a neutralization step of performing neutralization by mixing triethylamine after cooling urethane synthesized through the urethane synthesis step; a distilled water stirring step of adding and stirring distilled water to the neutralized urethane through the neutralization step; and an acetone removal step of removing the acetone contained in the urethane mixed with distilled water through the distilled water stirring step. According to the anionic water-dispersible polyurethane dispersion prepared through the steps, the acetone is used as a viscosity control agent and natural ingredients are used as a chain extender, without using a catalytic agent harmful to the human body. Therefore, a polyurethane film exhibiting excellent biodegradability, mechanical properties and transparency is provided.

Description

Method for producing anionic water-dispersed polyurethane dispersion and biodegradable polyurethane film prepared from the dispersion

The present invention relates to a method for preparing an anionic water-dispersed polyurethane dispersion and a biodegradable polyurethane film prepared from the dispersion, and more particularly, excellent biodegradability, mechanical properties and transparency without using a catalyst harmful to the human body. It relates to a method for preparing an anionic water-dispersed polyurethane dispersion providing a polyurethane film showing

Plastic has become a necessity of modern life because of its convenience, but it is frequently applied as a disposable product and is emerging as a serious social problem because it produces a large amount of household waste.

Plastics decompose very slowly in their natural state, and it is known that the rate of decomposition of plastics takes several tens to hundreds of years depending on the type. In addition, recently, the ocean is polluted with microplastics by plastics flowing into rivers or seas.

In order to solve the above problems, various types of degradable plastics are being developed. Currently, degradable plastics being developed are mainly photodegradable plastics that are decomposed by light (mainly ultraviolet) and biodegradable plastics that are decomposed by microorganisms. .

Biodegradable plastics can be classified into plastics (bioplastics) produced by microorganisms, plastics manufactured with natural materials such as starch or cellulose as main components, and chemically synthesized plastics with degradability. If all these are buried in the ground or left in the sea, they are decomposed by microorganisms in nature, such as bacteria, algae, and mold, to form low molecular weight compounds, and finally turn into water and carbon dioxide or water and methane gas.

However, conventional biodegradable plastics have limitations in that they are difficult to mold or have poor physical properties of products finished by molding, so that their practicality is poor.

On the other hand, in general, polyurethane is a generic term for high molecular compounds having a urethane bond (-NHCOO-) in the repeating unit of the main chain. It is widely used in foam, polyurethane rubber, adhesives, synthetic fibers, paints, etc., and can also be used in the manufacture of plastics. Polyurethane generally has decomposition properties such as hydrolysis and biodegradability by itself. However, since the decomposition property is very weak, there was a problem that the polyurethane product is not completely decomposed when discarded after use, but is partially decomposed to exist semi-permanently, or it takes a long time to decompose, causing environmental pollution.

Water-dispersed polyurethane is being developed to solve the above problems, but in the case of water-dispersed polyurethane, petroleum-based diol, diisocyanate and chain extender are used as raw materials, so it is not eco-friendly and harmful to the human body during the synthesis process. A catalyst or a viscosity modifier is used, and the application range is limited because the physical properties are not good, and there is a problem in that the biodegradability is lowered because nanoparticles such as graphite or carbon nanotubes are mixed to supplement the physical properties.

Republic of Korea Patent Registration No. 10-0352465 (2002.0.08.30.) Republic of Korea Patent No. 10-0751682 (2007.08.16.)

It is an object of the present invention to provide a polyurethane film exhibiting excellent biodegradability, mechanical properties and transparency by using acetone as a viscosity modifier and natural ingredients as a chain extender without using a catalyst harmful to the human body. To provide a method for preparing a polyurethane dispersion and a biodegradable polyurethane film prepared from the dispersion.

An object of the present invention is a raw material mixing step in which isophorone diisocyanate is added dropwise and stirred while stirring castor oil and dimethylol butanoic acid, acetone is mixed and synthesized in the mixture prepared through the raw material mixing step, a urethane synthesis step, the urethane synthesis After cooling the urethane synthesized through the step, a neutralization step of neutralizing by mixing triethylamine, a distilled water stirring step of adding distilled water to the urethane neutralized through the neutralization step and stirring, and distilled water mixed through the distilled water stirring step It is achieved by providing a method for preparing an anionic aqueous dispersion polyurethane dispersion, characterized in that it consists of an acetone removal step of removing the acetone contained in the urethane.

According to a preferred feature of the present invention, the raw material mixing step is 50 to 100 parts by weight of isophorone diisocyanate while stirring 10 to 30 parts by weight of dimethylol butanoic acid to 100 parts by weight of castor oil at a temperature of 75 to 80° C. and a speed of 200 to 300 rpm. It is supposed to be done by dropping the wealth.

According to a more preferred feature of the present invention, in the urethane synthesis step, 100 to 500 parts by weight of acetone is mixed with 100 parts by weight of castor oil contained in the mixture prepared through the raw material mixing step, and 60 to 120 minutes at a speed of 200 to 300 rpm. It is supposed to be made while stirring.

According to a more preferred feature of the present invention, in the neutralization step, the urethane synthesized through the urethane synthesis step is cooled to a temperature of 40 to 50° C., and then triethylamine is mixed, and at a speed of 300 to 400 rpm for 30 to 60 minutes. It is supposed to be made by stirring.

According to a more preferred feature of the present invention, in the distilled water stirring step, 0.01 to 5 parts by weight of a chain extender is further contained in 100 parts by weight of the distilled water, and the chain extender is selected from the group consisting of nanocellulose, chitin nanofiber, and carboxymethyl chitosan. It is supposed to consist of one or more.

In addition, the object of the present invention can be achieved by providing a biodegradable polyurethane film, characterized in that it is prepared by drying the anionic water-dispersed polyurethane dispersion prepared by the above manufacturing method after casting it on a glass plate on which a mold is installed. have.

According to a preferred feature of the present invention, the drying is carried out for 6 to 8 days in a thermo-hygrostat showing a temperature of 24 to 26 ° C and a relative humidity of 70 to 80%, and then 23 to 25 hours in a vacuum dryer at 28 to 32 ° C. to be done during

The method for producing a water-dispersed polyurethane dispersion according to the present invention and the biodegradable polyurethane film prepared from the dispersion are excellent by using acetone as a viscosity modifier and natural ingredients as a chain extender without using a catalyst harmful to the human body. It exhibits an excellent effect of providing a polyurethane film exhibiting biodegradability, mechanical properties and transparency.

1 is a flowchart showing a method for preparing an aqueous dispersion polyurethane dispersion according to the present invention.
Figure 2 is a reaction scheme showing a process for preparing anionic aqueous dispersion polyurethane dispersion by mixing distilled water according to the present invention.
3 is a reaction scheme showing a process for preparing an anionic aqueous dispersion polyurethane dispersion by mixing nanocellulose according to the present invention.
Figure 4 is a reaction scheme showing the process of preparing anionic aqueous dispersion polyurethane dispersion by mixing chitin nanofibers according to the present invention.
5 is a reaction scheme showing a process for preparing an anionic aqueous dispersion polyurethane dispersion using carboxymethylchitosan according to the present invention.
6 is a graph showing the viscosity change (a) and particle size (b) of the anionic aqueous dispersion polyurethane dispersion prepared through Preparation Examples 1 to 3 of the present invention measured.
7 to 8 are photographs showing the measurement of the transparency of the biodegradable polyurethane film prepared through Examples 1 to 14 of the present invention.
9 to 10 are graphs showing the measurement of the transmittance of the biodegradable polyurethane film prepared through Examples 1 to 5 and Examples 7 to 10 of the present invention.
11 to 13 are graphs showing the measurement of the mechanical strength of the biodegradable polyurethane film prepared through Examples 1 to 14 of the present invention.
14 is a graph showing the measurement of the biodegradability of the biodegradable polyurethane film prepared through Examples 1 to 5 of the present invention.

Hereinafter, a preferred embodiment of the present invention and the physical properties of each component will be described in detail, which is intended to describe in detail enough that a person of ordinary skill in the art to which the present invention pertains can easily carry out the invention, This does not mean that the technical spirit and scope of the present invention is limited.

The method for preparing an anionic water-dispersed polyurethane dispersion according to the present invention is to drop Isophorone Diisocyanate (IPDI) while stirring Castor Oil and dimethylolbutanoic acid (DMBA). Stirring raw material mixing step (S101), urethane synthesis step (S103) of mixing and synthesizing acetone with the mixture prepared through the raw material mixing step (S101), and cooling the urethane synthesized through the urethane synthesis step (S103) After the neutralization step (S105) of mixing and neutralizing triethylamine, distilled water is added to the urethane neutralized through the neutralization step (S105) and distilled water is stirred (S107) and distilled water through the stirring step (S107) consists of an acetone removal step (S109) of removing the acetone contained in the mixed urethane.

The raw material mixing step (S101) is a step of adding isophorone diisocyanate dropwise while stirring the castor oil and dimethylol butanoic acid and stirring, and 10 to 30 parts by weight of dimethylol butanoic acid to 100 parts by weight of the castor oil at a temperature of 75 to 80° C. It consists of a process of dropping 50 to 80 parts by weight of isophorone diisocyanate while stirring at a speed of 200 to 300 rpm.

At this time, the stirring of the castor oil, dimethylol butanoic acid and isophorone diisocyanate can be made in a four-necked flask equipped with a nitrogen inlet, a mechanical stirrer and a condenser.

The urethane synthesis step (S103) is a step of mixing and synthesizing acetone with the mixture prepared through the raw material mixing step (S101), and 100 parts by weight of castor oil contained in the mixture prepared through the raw material mixing step (S101) It is made by mixing 100 to 500 parts by weight of acetone and stirring at a speed of 200 to 300 rpm for 60 to 120 minutes, and the acetone is not added temporarily at once, but rather in the synthesis process of urethane or the viscosity of the mixture in the neutralization step. It is preferable to inject while observing.

The viscosity and particle size of the synthesized urethane can be adjusted by adjusting the content of acetone in the urethane synthesis step (S103).

The neutralization step (S105) is a step of neutralizing by mixing triethylamine after cooling the urethane synthesized through the urethane synthesis step (S103). The urethane synthesized through the urethane synthesis step (S103) is 40 to 50 After cooling to a temperature of ℃, 15 to 20 parts by weight of triethylamine based on 100 parts by weight of castor oil contained in the urethane is mixed and stirred at a speed of 300 to 400 rpm for 30 to 60 minutes.

The distilled water stirring step (S107) is a step of adding distilled water to the urethane neutralized through the neutralization step (S105) and stirring, the urethane neutralized with triethylamine through the neutralization step (S105) at a speed of 550 to 650 rpm It consists of a process of mixing 100 to 300 parts by weight of distilled water while stirring and stirring for 100 to 150 minutes.

The process of preparing an anionic aqueous dispersion polyurethane dispersion by mixing distilled water as described above is shown in FIG. 2 below.

In this case, 0.01 to 5 parts by weight of a chain extender may be further contained relative to 100 parts by weight of the distilled water, and the chain extender is nanocellulose (RCNs), chitin nanofibers (ChNF) and carboxymethyl chitosan (Carboxymethyl Chitosan, CS) It is preferably made of one or more selected from the group consisting of.

The process of preparing an anionic water-dispersed polyurethane dispersion using nanocellulose as a chain extender as described above is shown in FIG. 3 below, and an anionic water-dispersed polyurethane dispersion using chitin nanofibers as the chain extender. The process is shown in FIG. 4 below, and the process of preparing an anionic aqueous dispersion polyurethane dispersion using carboxymethylchitosan as the chain extender is shown in FIG. 5 below.

At this time, the nanocellulose is nanocellulose (RCNs) regenerated from microcellulose (MCC) to a pH of 8 using sodium hydroxide (NaOH) and urea (Urea), and exhibits semi-crystalline particle characteristics with low crystallinity, mass concentration Using sodium hydroxide of 7% and urea having a mass concentration of 12%, and a solution containing microcellulose (MCC) having a mass concentration of 5% was stirred at room temperature for 2 hours, and placed in a refrigerator at a temperature of -20°C for 12 hours. After storage, it can be prepared by sonicating the solution obtained through precipitation and separation of cellulose regenerated through centrifugation and adjusting the pH to about 8.

The chain extender composed of the above components not only improves mechanical properties by increasing the molecular weight of the polyurethane film prepared from the anionic water-dispersed polyurethane dispersion according to the present invention, but also improves biodegradability of poly It serves to provide a urethane film.

The acetone removal step (S109) is a step of removing the acetone contained in the urethane mixed with distilled water through the distilled water stirring step (S107), and the acetone contained in the distilled water mixed urethane through the distilled water stirring step (S107) is removed using a vacuum dryer, and the urethane from which acetone has been removed through the above process is prepared as an anionic aqueous dispersion polyurethane dispersion having a mass concentration of 18 to 20%.

In addition, the biodegradable polyurethane film according to the present invention consists of a process of drying after casting the anionic water-dispersed polyurethane dispersion prepared through the acetone removal step (S109) on a glass plate on which a mold is installed, wherein the drying is After the polyurethane film was prepared by first drying for 6 to 8 days in a constant temperature and humidifier showing a temperature of 24 to 26 ° C and a relative humidity of 70 to 80%, the polyurethane film was dried in a vacuum dryer at 28 to 32 ° C. 23 It is preferable to consist of a process of further drying for 25 hours.

The polyurethane film produced through the above process may exhibit a transparency of 75% or more, and a biodegradability of up to 15% or more after 370 hours.

Hereinafter, the method for preparing an anionic water-dispersed polyurethane dispersion according to the present invention and the physical properties of the biodegradable polyurethane film prepared with the dispersion prepared by the manufacturing method will be described with reference to Examples.

<Production Example 1>

22.497 g of castor oil and 3.465 g of DMBA were put into a four-neck flask equipped with a nitrogen inlet, mechanical stirrer and condenser, and 16.748 g of IPDI was added dropwise while stirring at 250 rpm at 78 ° C., 40.086 g of acetone was mixed and 90 at a speed of 250 rpm. After stirring for a minute to synthesize urethane, after cooling the synthesized urethane to 40° C., 4.095 g of triethylamine was mixed and neutralized by stirring at 350 rpm for 30 minutes, and 150 mL of distilled water while stirring the neutralized urethane at a speed of 600 rpm After adding and stirring for 120 minutes, an anionic aqueous dispersion polyurethane dispersion (CWPU 1/2.08/0.65) was prepared through the process of removing acetone using a vacuum dryer (DAIHAN Scientific, KOREA).

<Production Example 2>

Proceeds in the same manner as in Preparation Example 1, except that 5.317 g of DMBA was added and 34.584 g of acetone was used to prepare an anionic aqueous dispersion polyurethane dispersion (CWPU 1/2.08/0.99).

<Production Example 3>

Proceeds in the same manner as in Preparation Example 1, except that 6.3912 g of DMBA was added, IPDI 17.727 g and acetone 61.308 g were used to prepare an anionic aqueous dispersion polyurethane dispersion (CWPU 1/2.20/1.19).

<Example 1>

The anionic water-dispersed polyurethane dispersion prepared in Preparation Example 1 was cast on a glass plate with a mold installed and dried in a constant temperature and humidity machine (25° C., relative humidity 75%) for 7 days, followed by a vacuum dryer (30° C.) and dried for 24 hours to prepare a biodegradable polyurethane film (CWPU).

<Example 2>

22.497 g of castor oil and 3.465 g of DMBA were put into a four-neck flask equipped with a nitrogen inlet, mechanical stirrer and condenser, and 16.748 g of IPDI was added dropwise while stirring at 250 rpm at 78 ° C., 40.086 g of acetone was mixed and 90 at a speed of 250 rpm. After stirring for a minute to synthesize urethane, after cooling the synthesized urethane to 40 ° C, 4.095 g of triethylamine was mixed and neutralized by stirring at 350 rpm for 30 minutes, and 145 mL of distilled water while stirring the neutralized urethane at a speed of 600 rpm And 0.05 g of nanocellulose was added and stirred for 120 minutes, and then an anionic water-dispersed polyurethane dispersion was prepared through a process of removing acetone using a vacuum dryer (DAIHAN Scientific, KOREA), and the prepared anionic water-dispersed poly The urethane dispersion is cast on a glass plate with a mold installed and dried for 7 days in a constant temperature and humidity machine (25 ° C., relative humidity 75%), and then dried in a vacuum dryer (30 ° C.) for 24 hours to form a biodegradable polyurethane film (CWPU). /RNC 0.18) was prepared.

<Example 3>

The same procedure as in Example 2, except that 140 mL of distilled water and 0.1 g of nanocellulose were added to prepare a biodegradable polyurethane film (CWPU/RNC 0.37).

<Example 4>

The same procedure as in Example 2, except that 135 mL of distilled water and 0.15 g of nanocellulose were added to prepare a biodegradable polyurethane film (CWPU/RNC 0.58).

<Example 5>

The same procedure as in Example 2, except that 130 mL of distilled water and 0.2 g of nanocellulose were added to prepare a biodegradable polyurethane film (CWPU/RNC 0.76).

<Example 6>

Put 14.998 g of castor oil and 2.79 g of DMBA into a four-necked flask equipped with a nitrogen inlet, mechanical stirrer, and condenser, and add 11.13 g of IPDI dropwise while stirring at 250 rpm at 78 ° C. Then, 28.296 g of acetone is mixed and 90 at a speed of 250 rpm After stirring for a minute to synthesize urethane, and after cooling the synthesized urethane to 50 ° C, 2.7225 g of triethylamine was mixed and neutralized by stirring at 350 rpm for 60 minutes, and 150 mL of distilled water while stirring the neutralized urethane at a speed of 600 rpm And 0.5 g of chitin nanofibers were added and stirred for 120 minutes, and then an anionic aqueous dispersion polyurethane dispersion was prepared through a process of removing acetone using a vacuum dryer (DAIHAN Scientific, KOREA), and the prepared anionic aqueous dispersion The polyurethane dispersion was cast on a glass plate with a mold installed and dried for 7 days in a constant temperature and humidity machine (25 ° C., relative humidity 75%), and then dried in a vacuum dryer (30 ° C.) for 24 hours to make a biodegradable polyurethane film ( CWPU/ChNF 0.13) was prepared.

<Example 7>

Proceeded in the same manner as in Example 6, but 0.75 g of chitin nanofibers were added to prepare a biodegradable polyurethane film (CWPU/ChNF 0.35).

<Example 8>

The same procedure as in Example 6, except that 1.5 g of chitin nanofibers were added to prepare a biodegradable polyurethane film (CWPU/ChNF 1.08).

<Example 9>

The same procedure as in Example 6, but 2.0 g of chitin nanofibers were added to prepare a biodegradable polyurethane film (CWPU/ChNF 2.17).

<Example 10>

Except in the same manner as in Example 6, 5.0 g of chitin nanofibers were added to prepare a biodegradable polyurethane film (CWPU/ChNF 21.7).

<Example 11>

Put 10 g of castor oil and 1.86 g of DMBA into a 4-neck flask equipped with a nitrogen inlet, mechanical stirrer and condenser, and add 7.42 g of IPDI while stirring at 250 rpm at 78 ° C. urethane is synthesized by stirring for After adding 0.405 g of carboxymethyl chitosan and stirring for 120 minutes, an anionic water-dispersed polyurethane dispersion was prepared through the process of removing acetone using a vacuum dryer (DAIHAN Scientific, KOREA), and the prepared anionic water-dispersed poly The urethane dispersion is cast on a glass plate with a mold installed and dried for 7 days in a constant temperature and humidity machine (25 ° C., relative humidity 75%), and then dried in a vacuum dryer (30 ° C.) for 24 hours to form a biodegradable polyurethane film (CWPU). /CS 1.13) was prepared.

<Example 12>

The same procedure as in Example 11, but 0.810 g of carboxymethylchitosan was added to prepare a biodegradable polyurethane film (CWPU/CS 2.25).

<Example 13>

The same procedure as in Example 11, except that 1.620 g of carboxymethyl chitosan was added to prepare a biodegradable polyurethane film (CWPU/CS 4.47).

<Example 14>

The same procedure as in Example 11, but 2.430 g of carboxymethyl chitosan was added to prepare a biodegradable polyurethane film (CWPU/CS 6.75).

The viscosity change (a) and particle size (b) of the anionic aqueous dispersion polyurethane dispersion prepared in Preparation Examples 1 to 3 were measured and shown in FIG. 6 below.

As shown in FIG. 6 below, the anionic aqueous dispersion polyurethane dispersions prepared in Preparation Examples 1 to 3 of the present invention have various viscosities and particle sizes according to the contents of castor oil, dimethylol butanoic acid, isophorone diisocyanate and acetone. can be seen to indicate

In addition, the transparency of the biodegradable polyurethane film prepared in Examples 1 to 14 was measured and shown in FIGS. 7 to 8 below.

As shown in FIGS. 7 to 8 below, as in Examples 2 to 14 of the present invention, even if nanocellulose, chitin nanofiber and carboxymethyl chitosan are contained to improve the physical properties of the polyurethane film, the biodegradable poly prepared in Example 1 It can be seen that the transparency is not significantly reduced compared to the urethane film.

In addition, the transmittance of the biodegradable polyurethane film prepared in Examples 1 to 5 and Examples 7 to 10 was measured and shown in FIGS. 9 to 10 below.

As shown in FIGS. 9 to 10 below, the polyurethane films prepared through Examples 2 to 5 and Examples 7 to 10 of the present invention exhibited transmittance comparable to that of the polyurethane film prepared through Example 1, and all It can be seen that the transmittance is 75% or more.

In addition, the mechanical strength of the biodegradable polyurethane film prepared in Examples 1 to 14 was measured and shown in FIGS. 11 to 13 below.

{However, the mechanical strength is measured after specimens of the biodegradable polyurethane films prepared in Examples 1 to 14 to a size of 20 mm in length and 5 mm in width, tensile strength, strain, and initial A method of measuring elastic modulus and toughness using a tensile tester AGS-500D (Autograph, Japan) was used.}

11 to 13 below, as in Examples 2 to 14 of the present invention, when nanocellulose, chitin nanofiber and carboxymethyl chitosan are contained, it can be seen that the mechanical strength of the polyurethane film is remarkably improved.

In addition, the degree of biodegradation of the biodegradable polyurethane film prepared in Examples 1 to 5 was measured and shown in FIG. 14 below.

{However, the degree of biodegradation of the biodegradable polyurethane film prepared in Examples 1 to 5 is

1. By adjusting the biodegradable polyurethane film prepared in Examples 1 to 5 to 0.225 g, prepare three for each condition,

2. Preparation of Citrate Buffer

2-1. DDW 800ml + Sodium Citrate 6.702g

2-2. Solution #1 + Citric Acid 5.227g

2-3. stirring 2h

2-4. pH 4.3

3. Add 45mL Citrate Buffer to 50mL conical tube

4. Add each film in No. 3 and measure the swelling weight after 1 hr

5. Add 0.0135g of Cellulase (add 0.027g after *40h)

6. Weigh each film

7. Based on the maximum swelling time of each film, a method of expressing weight loss in % was used. ※ film 0.225g: Citric buffer (pH4.3) 45ml: Cellulase 0.040g}

As shown in FIG. 14 below, the polyurethane films prepared through Examples 1 to 5 of the present invention exhibited excellent biodegradability, and in particular, the polyurethane film prepared through Example 5 of the present invention exhibited the best biodegradability. it can be seen that

Therefore, the method for producing a water-dispersed polyurethane dispersion according to the present invention and the biodegradable polyurethane film prepared from the dispersion use acetone as a viscosity modifier and a natural component as a chain extender without using a catalyst harmful to the human body. Thus, it is possible to provide a polyurethane film exhibiting excellent biodegradability, mechanical properties, and transparency.

S101; Raw material mixing step
S103; Urethane synthesis step
S105 ; neutralization stage
S107; Distilled water stirring step
S109; Acetone removal step

Claims (7)

A raw material mixing step of adding isophorone diisocyanate dropwise while stirring castor oil and dimethylol butanoic acid and stirring;
A urethane synthesis step of mixing and synthesizing acetone with the mixture prepared through the raw material mixing step;
a neutralization step of neutralizing the urethane synthesized through the urethane synthesis step by mixing triethylamine after cooling;
Distilled water stirring step of adding distilled water to the urethane neutralized through the neutralization step and stirring; and
An acetone removal step of removing the acetone contained in the urethane mixed with distilled water through the distilled water stirring step;
The method according to claim 1,
The raw material mixing step is performed by dropping 50 to 80 parts by weight of isophorone diisocyanate to 100 parts by weight of castor oil while stirring 10 to 30 parts by weight of dimethylol butanoic acid at a temperature of 75 to 80° C. and a speed of 200 to 300 rpm. A method for preparing an anionic water-dispersed polyurethane dispersion.
The method according to claim 1,
The urethane synthesis step is an anion, characterized in that by mixing 100 to 500 parts by weight of acetone with respect to 100 parts by weight of castor oil contained in the mixture prepared through the raw material mixing step and stirring at a speed of 200 to 300 rpm for 60 to 120 minutes A method for preparing an aqueous dispersion polyurethane dispersion.
The method according to claim 1,
The neutralization step is anionic, characterized in that the urethane synthesized through the urethane synthesis step is cooled to a temperature of 40 to 50° C., then triethylamine is mixed and stirred at a speed of 300 to 400 rpm for 30 to 60 minutes. A method for preparing an aqueous dispersion polyurethane dispersion.
The method according to claim 1,
In the distilled water stirring step, 0.01 to 5 parts by weight of a chain extender is further contained in 100 parts by weight of the distilled water,
The chain extender is a method for producing an anionic aqueous dispersion polyurethane dispersion, characterized in that consisting of at least one selected from the group consisting of nanocellulose, chitin nanofibers and carboxymethyl chitosan.
A biodegradable polyurethane film, characterized in that it is prepared by casting the anionic water-dispersed polyurethane dispersion prepared by the manufacturing method according to any one of claims 1 to 5 on a glass plate on which a mold is installed and then drying.
7. The method of claim 6,
The drying is carried out for 6 to 8 days in a thermo-hygrostat showing a temperature of 24 to 26° C. and a relative humidity of 70 to 80%, followed by 23 to 25 hours in a vacuum dryer at 28 to 32° C. Biodegradable polyurethane film.

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