KR101826976B1 - Manufacturing method of polyester polyol at low temperature using perovskite catalyst - Google Patents

Abstract

The present invention relates to a polyester polyol preparing method. The polyester polyol preparing method includes the steps of: (1) mixing a citric acid and a metal precursor which is an ingredient of a perovskite catalyst to obtain a gel phase compound; (2) obtaining a perovskite catalyst represented by chemical formula 1, ABO_3, by firing the obtained gel phase compound at the temperature of 600-1,000°C; (3) mixing 1 to 100 parts by weight of a polycarboxylic acid and 1 to 500 parts by weight of a polyhydric alcohol having a molecular weight of 40 to 55,000 and melting the mixture at 100-150°C; and (4) adding 0.0001 to 10.0 parts by weight of the obtained perovskite catalyst to 100 parts by weight of the melt mixture and initiating a reaction at 160-210°C. According to the present invention, the polyester polyol preparing method can lower the reaction temperature by using a specific perovskite catalyst while improving the recovery rate of the polyester polyol and colors. In chemical formula 1, A and B are elements which are mutually different and are individually any one selected from La, Mo and Mn.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyester polyol at a low temperature using a perovskite catalyst,

The present invention relates to a process for preparing polyester polyols from polyvalent carboxylic acids and polyhydric alcohols using perovskite catalysts.

)을 갖는 고분자 화합물로서, 원료 및 적용기술에 따라서 자동차·가구용 쿠션재, 건축물의 단열재, 접착제, 방수제, 바닥재, 인조가죽, 코팅제, 실링(Sealing)제 및 인조섬유 등 모든 산업분야에 널리 활용되고 있는 고분자 소재로 최근 많은 주목을 받고 있다. The polyurethane is a urethane bond obtained by a chemical reaction between a substance containing an isocyanate group (-NCO-) and a substance having active hydrogen

) Is widely used in all industrial fields such as automobile and furniture cushioning materials, insulation materials for buildings, adhesives, waterproofing agents, flooring materials, artificial leather, coating agents, sealants and man-made fibers depending on raw materials and application techniques Recently, it has attracted much attention as a polymer material.

In general, polyol may be used as a material having an active hydrogen which is used for synthesis of polyurethane. Such a polyol may be an amine, a phenol, an alcohol, water (H ₂ O) An active methylene compound or the like as an initiator.

Polyols can be classified into various types according to their chemical structures. Among them, polyester polyol and polyether polyol are most commonly used. Among them, the catalyst used for the synthesis of the polyester polyol generally includes tetraisopropyl titanate, p-toluene sulfate, dibutyl tin dilaurate, tetrabutoxy titanium, lithium acetate, calcium acetate, zinc acetate, manganese acetate and the like .

However, when these catalysts are used in the polyester polyol production process, a relatively high process temperature of 210 to 250 ° C. is generally required. When the reaction is carried out at 210 ° C. or more, a low boiling point solvent There is a problem in that the recovery rate of the product decreases as volatilization occurs.

The inventors of the present invention have focused on this technical requirement and have completed the present invention by synthesizing a polyester polyol at a low temperature using a specific catalyst having a perovskite structure.

KR 10-0966870 B

An object of the present invention is to provide a process for producing a polyester polyol having an improved recovery rate and improved color using a specific perovskite catalyst.

In order to achieve the above object, the present invention provides a process for producing a perovskite catalyst, comprising the steps of: (1) mixing a metal precursor, which is a raw material of a perovskite catalyst, and citric acid to obtain a gel phase compound; (2) firing the obtained gel-like compound at a temperature of 600 to 1000 ° C to obtain a perovskite catalyst represented by the following formula (1); (3) 1 to 100 parts by weight of a polycarboxylic acid and 1 to 500 parts by weight of a polyhydric alcohol having a molecular weight of 60 to 55,000 and melting at 100 to 150 ° C; and (4) Wherein the catalyst is reacted at 160 to 210 DEG C by adding 0.0001 to 10.0 parts by weight of a skeletal catalyst based on the molten mixture.

[Chemical Formula 1]

ABO ₃

(Wherein, in the above formula, A and B are elements which are not mutually identical and are each selected from La, Mo and Mn).

The process for producing a polyester polyol according to the present invention can lower the reaction temperature by using a specific perovskite catalyst, thereby improving the recovery rate of the polyester polyol and improving the color.

1 is a schematic representation of a process for producing a polyester polyol according to an embodiment of the present invention.
2 is a photograph of a polyester polyol prepared according to Example 1 and Comparative Example 1. Fig.

The present invention relates to a process for preparing polyester polyols from polyvalent carboxylic acids and polyhydric alcohols using perovskite catalysts.

The reactor, the condenser, the reflux condenser, the nitrogen reflux condenser, and the stirrer described in the present specification are used in the process of manufacturing the polyester polyol and are not specifically described in the embodiments of the present invention. However, And can be easily understood by a person skilled in the art.

According to an aspect of the present invention, there is provided a method for producing a perovskite catalyst, comprising the steps of: (1) mixing a metal precursor, which is a raw material of a perovskite catalyst, and citric acid to obtain a gel phase compound; (2) firing the obtained gel-like compound at a temperature of 600 to 1000 ° C to obtain a perovskite catalyst represented by the following formula (1); (3) 1 to 100 parts by weight of a polycarboxylic acid and 1 to 500 parts by weight of a polyhydric alcohol having a molecular weight of 60 to 55,000 and melting at 100 to 150 ° C; and (4) Wherein the catalyst is reacted at 160 to 210 DEG C by adding 0.0001 to 10.0 parts by weight of a skeletal catalyst based on the molten mixture.

[Chemical Formula 1]

ABO ₃

(Wherein, in the above formula, A and B are elements which are not mutually identical and are each selected from La, Mo and Mn).

1 is a schematic representation of a process for producing a polyester polyol according to an embodiment of the present invention. Hereinafter, the present invention will be described with reference to Fig.

First, the step (1) for obtaining a gel phase compound will be described.

A step of mixing a raw material such as a metal precursor to obtain a perovskite catalyst to be used for producing a polyester polyol. Perovskite is a metal oxide of a crystal structure having the formula of ABO ₃ , and A and B are cations located at the center of a crystal lattice surrounded by lattice oxygen. In the above formula, A and B are not identical to each other and may be any one selected from La, Mo and Mn, and the characteristics of the perovskite catalyst may be changed as the kind of the corresponding metal cation is changed.

The method for obtaining the perovskite catalyst is not particularly limited, but the citric acid method, the Phechni method, the high temperature aging method and the polymerization complex method can be used. As a preferred example, the citric acid method can be used.

The metal precursor solution is dissolved in a solvent to prepare a metal precursor solution. The metal precursor is a raw material of a metal constituting the perovskite catalyst, and may be an oxide, a nitrate or a sulfur oxide of La, Mo and Mn. Specifically, La ₂ O ₃ , Mo ₂ O ₃ , Mn ₂ O _{3, La (NO 3) 3} , Mo (NO 3) 3, Mn (NO 3) 3, La 2 (SO 3) 3, Mo 2 (SO 3) 3 and the like Mn ₂ (SO _{3) 3} But is not limited thereto. As a preferred embodiment of the present invention, La (NO ₃ ) ₃ , Mo (NO ₃ ) ₃ and Mn (NO ₃ ) ₃ can be used as the metal precursor.

As the solvent, any solvent may be used, and a protic solvent, aprotic solvent or distilled water may be used. Specific examples of the solvent include protophilic solvents such as dimethylformamide, gamma butyrolactone, N-methylpyrrolidone, dimethylsulfoxide and an aprotic solvent such as dichloroethylene a solvent such as dichloroethylene, trichloroethylene, chloroform, chlorobenzene, dichlorobenzene, styrene, dimethylformamide, dimethylsulfoxide, Xylene, toluene, cyclohexene, and isopropyl alcohol. However, the solvent is not limited thereto. For example, distilled water may be used as a solvent.

Next, citric acid is mixed with the metal precursor solution and stirred. The solvent is heated to a constant temperature in order to volatilize the solvent, and a gel phase compound can be obtained as the solvent is volatilized.

The heating temperature at this time may be 60 to 120 ° C, preferably 80 to 100 ° C, more preferably 85 to 95 ° C. If the heating temperature is lower than 60 ° C, there is a problem that the time required to obtain the gel-like compound becomes long. When the heating temperature is more than 120 ° C, the solvent is excessively volatilized and a desired gel-like compound can not be obtained.

The heating and stirring time may be 1 to 3 hours, and preferably 1.5 to 2.5 hours. If the heating and agitation time is less than 1 hour, there may be a problem that the solvent is not volatilized. If the heating and stirring time is more than 3 hours, the solvent is excessively volatilized and a desired gel-like compound can not be obtained.

Next, the step (2) for obtaining a perovskite catalyst will be described.

The gel phase compound obtained in the step (1) is subjected to a calcination step to obtain a perovskite catalyst.

The firing temperature at this time may be 600 to 1,000 占 폚, preferably 700 to 900 占 폚, and more preferably 750 to 850 占 폚. The firing time may also be 4 to 8 hours, preferably 5 to 7 hours. If the firing temperature and time do not fall within the above range, there is a problem that the perovskite structure is not sufficiently generated. If the firing temperature and time are out of the above range, the compound obtained in the step (1) have.

A specific perovskite catalyst can be obtained through such a calcination process. The perovskite catalyst obtained at this time may be characterized by being LaMnO ₃ , LaMoO ₃ , MnMoO _3, or a mixture thereof.

Next, the step (3) of mixing raw materials for synthesizing a polyester polyol will be described.

)을 갖는 고분자로서 분자의 말단에 2개 이상의 수산화기(-OH)를 갖는 화합물을 의미한다. 이러한 폴리에스테르 폴리올은 다가카르복실산과 다가알코올 간의 탈수축합반응에 의해 합성될 수 있으며, 이 때 상기 수득한 페로브스카이트 촉매를 사용할 수 있다.The polyester polyol is an ester bond (

) As a polymer having two or more hydroxyl groups (-OH) at the terminal of the molecule. Such a polyester polyol can be synthesized by a dehydration condensation reaction between a polyvalent carboxylic acid and a polyhydric alcohol, and the perovskite catalyst thus obtained can be used.

First, the polycarboxylic acid and the polyhydric alcohol are mixed and heated to be completely melted. The heating temperature at this time is preferably 100 to 150 ° C, more preferably 120 to 140 ° C. If the heating temperature is less than 100 캜, there is a problem that the raw material is not sufficiently melted. If the heating temperature is more than 150 캜, the volatilized amount of the raw material is increased and the recovery rate is lowered.

In this case, the polyvalent carboxylic acid may be added in an amount of 1 to 100 parts by weight, preferably 5 to 80 parts by weight, more preferably 10 to 60 parts by weight. The polyhydric alcohol may be added in an amount of 1 to 500 parts by weight, preferably 10 to 400 parts by weight, more preferably 20 to 200 parts by weight. When the polyvalent carboxylic acid and the polyhydric alcohol are mixed in the above weight range, a polyester polyol having excellent physical properties can be produced and the recovery rate can be increased.

The polycarboxylic acid as a raw material for synthesizing polyester polyol means a carboxylic acid molecule having a plurality of carboxyl groups (-COOH) in one molecule. Specific examples thereof include adipic acid, maleic anhydride, sebacic acid, isophthalic acid, phthalic anhydride, terephthalic acid, oxalic acid, Examples thereof include malonic acid, fumaric acid, citric acid, tartaric acid and the like, and preferred examples thereof include phthalic anhydride, adipic acid, Maleic acid, maleic anhydride, sebacic acid, citric acid, tartaric acid, terephthalic acid, and mixtures thereof.

In another preferred embodiment of the present invention, a phthalic anhydride by-product can be used as the polycarboxylic acid. Here, the by-product phthalic anhydride means a by-product generated in the process of producing phthalic anhydride.

The polyhydric alcohol which is another raw material for the synthesis of the polyester polyol means an alcohol molecule having a plurality of hydroxyl groups (-OH) in one molecule, and is a compound represented by the following formulas (2) to (4) Any one selected may be used.

(2)

(3)

[Chemical Formula 4]

(Wherein n is an integer of 1 to 100, and R ₁ and R ₂ are each H, a C ₁ to C ₁₈ hydrocarbon compound or a C ₁ to C ₁₈ hydroxyalkyl group.)

More specifically, polyhydric alcohols include, for example, methylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, Tripropylene glycol, butanediol, pentanediol, hexanediol, heptanediol, polyethylene glycol, polypropylene glycol, glycerol, and the like. ), Trimethylol propane, pentaerythritol, methyl glucoside, sorbitol, sucrose and the like can be used. As a preferred example, diethylene glycol (Ethylene glycol), propylene glycol, dipropylene glycol, polyethylene glycol, polypropylene Recall (Polypropylene glycol), glycerol (Glycerol), can be used any one selected from pentaerythritol (Pentaerythritol), sorbitol (Sorbitol), can Crows (Sucrose), and mixtures thereof.

The polyhydric alcohol may be a polyhydric alcohol having a molecular weight of 40 to 55,000, preferably 40 to 30,000, and more preferably 40 to 10,000. When polyhydric alcohols having a molecular weight of more than 55,000 are used, polyhydric alcohols having a molecular weight of 40 to 55,000 are used because the synthesis time is prolonged due to a problem of lowering reactivity.

After the mixture of the polycarboxylic acid and the polyhydric alcohol is sufficiently melted, the obtained perovskite catalyst is added. The perovskite catalyst may be added in an amount of 0.0001 to 10.0 parts by weight, preferably 0.001 to 1.0 part by weight, more preferably 0.01 to 0.5 parts by weight, based on the total weight of the polycarboxylic acid and the polyhydric alcohol mixture have. If the perovskite catalyst is added in an amount of less than 0.0001 part by weight based on the weight of the polyvalent carboxylic acid and polyhydric alcohol mixture, the activity as a catalyst is not sufficiently exhibited. If the amount exceeds 10.0 parts by weight, There is a problem that the effect of the present invention is weak.

After the perovskite catalyst is added, the temperature is gradually raised to induce the reaction. At this time, the reaction temperature may be 160 to 210 ° C, preferably 170 to 200 ° C, and more preferably 180 to 190 ° C. If the reaction temperature is lower than 160 ° C, the synthesis of the polyester polyol may not be sufficiently performed. If the reaction temperature is higher than 210 ° C, the azeotrope due to the reaction water generated during the synthesis reaction lowers the recovery rate of the product as the low boiling point solvent is volatilized There is a problem.

After completion of the synthesis reaction using the polyvalent carboxylic acid, polyhydric alcohol and perovskite catalyst, the product can be cooled to produce the polyester polyol.

The polyester polyol prepared according to one embodiment of the present invention is characterized by using the perovskite catalyst represented by the above formula (1), and compared with the polyester polyol prepared by using a commercially available metal catalyst There is no difference in its properties. Further, by using the perovskite catalyst represented by the above formula (1), it is possible to synthesize a polyester polyol at a relatively low temperature, thereby preventing the solvent of a low boiling point from being volatilized during the synthesis reaction, . In addition, since the reaction for promoting the oxidation can be controlled by proceeding the synthesis reaction at a relatively low temperature, the effect of improving the color of the polyester polyol is exhibited.

Hereinafter, the present invention will be described in more detail with reference to Examples.

It is to be understood by those skilled in the art that these embodiments are only for describing the present invention in more detail and that the scope of the present invention is not limited by these embodiments in accordance with the gist of the present invention.

<Examples>

Example 1

32 g of metal precursors La (NO ₃ ) ₃ , 22 g of Mo (NO ₃ ) ₃ and 36 g of Mn (NO ₃ ) ₃ were dissolved in distilled water to prepare a metal precursor solution. 19 g of citric acid was added to the metal precursor solution, and the mixture was stirred at room temperature for 2 hours. Then, the temperature was raised to 90 DEG C and the distilled water was volatilized while stirring. The thus obtained gel-state compound was calcined at 800 DEG C for 6 hours to obtain a perovskite catalyst.

Next, 150 g of phthalic anhydride and 200 g of diethylene glycol (DEG) were added to a 1 L flask equipped with a thermometer, a reflux condenser, a nitrogen reflux condenser, and a stirrer and completely melted at 140 ° C. Then, the obtained perovskite catalyst was added in an amount of 0.1 wt% based on the weight of the mixture of the polycarboxylic acid and the polyhydric alcohol, and the temperature was raised at a rate of 10 ° C / min to carry out the synthesis reaction at 180 ° C. Thus, the synthesized product was cooled to prepare a polyester polyol.

Example 2

A polyester polyol was prepared in the same manner as in Example 1, except that 130 g of adipic acid was used instead of phthalic anhydride.

Example 3

A polyester polyol was prepared in the same manner as in Example 1, except that 100 g of maleic anhydride was used instead of phthalic anhydride.

Example 4

A polyester polyol was prepared in the same manner as in Example 1 except that 190 g of sebacic acid was used instead of phthalic anhydride.

Example 5

A polyester polyol was prepared in the same manner as in Example 1 except that 100 g of citric acid was used instead of phthalic anhydride.

Example 6

A polyester polyol was prepared in the same manner as in Example 1 except that 90 g of tartaric acid was used instead of phthalic anhydride.

Example 7

A polyester polyol was prepared in the same manner as in Example 1, except that 60 g of phthalic anhydride and 100 g of terephthalic acid were used instead of 150 g of phthalic anhydride.

Example 8

A polyester polyol was prepared in the same manner as in Example 1, except that 60 g of phthalic anhydride, 60 g of terephthalic acid and 60 g of adipic acid were used instead of 150 g of phthalic anhydride. Respectively.

Example 9

A polyester polyol was prepared in the same manner as in Example 1, except that 180 g of anhydrous phthalic acid by-product generated in the process of producing phthalic anhydride was used instead of phthalic anhydride.

The raw material contents for Examples 1 to 9 are shown in Table 1 below.

[Table 1]

Example 10

A polyester polyol was prepared in the same manner as in Example 1 except that 220 g of propylene glycol (hereinafter PG) was used instead of diethylene glycol (DEG).

Example 11

A polyester polyol was prepared in the same manner as in Example 1 except that 250 g of dipropylene glycol (hereinafter referred to as DPG) was used instead of diethylene glycol (DEG).

Example 12

A polyester polyol was prepared in the same manner as in Example 1, except that 800 g of polyethylene glycol 600 (hereinafter referred to as PEG 600; PEM 600) was used instead of diethylene glycol (DEG).

Example 13

A polyester polyol was prepared in the same manner as in Example 1, except that 1,500 g of polyethylene glycol 1000 (hereinafter referred to as PEG 1000; PEG 1000) was used instead of diethylene glycol (DEG).

Example 14

A polyester polyol was prepared in the same manner as in Example 1, except that 800 g of polypropylene glycol 600 (hereinafter referred to as &quot; PPG 600 &quot;; available from Samseong Chemical) was used instead of diethylene glycol (DEG).

Example 15

A polyester polyol was prepared in the same manner as in Example 1, except that 1,500 g of polypropylene glycol 1000 (hereinafter referred to as PPG 1000; Samseon Chemical) instead of diethylene glycol (DEG) was used.

Example 16

A polyester polyol was prepared in the same manner as in Example 1 except that 160 g of diethylene glycol (DEG) and 50 g of glycerol were used instead of 220 g of diethylene glycol (DEG).

Example 17

A polyester polyol was prepared in the same manner as in Example 1, except that 165 g of diethylene glycol (DEG) and 34 g of pentaerythritol were used instead of 220 g of diethylene glycol (DEG).

Example 18

A polyester polyol was prepared in the same manner as in Example 1 except that 220 g of diethylene glycol (DEG) was replaced by 180 g of diethylene glycol (DEG) and 28 g of sorbitol.

Example 19

A polyester polyol was prepared in the same manner as in Example 1, except that 190 g of diethylene glycol (DEG) and 15 g of sucrose were used instead of 220 g of diethylene glycol (DEG).

Example 20

Except that 220 g of diethylene glycol (DEG) was replaced by 100 g of diethylene glycol (DEG), 400 g of polyethylene glycol 600 (PEG 600; Samseon Chemical) and 50 g of glycerol, To prepare a polyol.

The raw material contents for Examples 10 to 20 are shown in Table 2 below.

[Table 2]

Comparative Examples 1 to 9

A polyester polyol was prepared in the same manner as in Examples 1 to 9 except that dibutyltin dilaurate (Sigma-aldrich) was used instead of organotin extracted from waste acid.

The raw material contents of Comparative Examples 1 to 9 are shown in Table 3 below.

[Table 3]

Comparative Examples 10 to 20

A polyester polyol was prepared in the same manner as in Examples 10 to 20 except that dibutyltin dilaurate (Sigma-aldrich) was used instead of organotin extracted from waste acid.

The raw material contents of Comparative Examples 10 to 20 are shown in Table 4 below.

[Table 4]

<Evaluation and Results>

The OH-V value and viscosity of the polyester polyol prepared according to Examples 1 to 20 and Comparative Examples 1 to 20 were measured to evaluate the quality of the polyester polyol. The recovery rate of the polyester polyol according to the following formula Respectively.

[Equation 1]

(Wherein X is an input amount of a polycarboxylic acid, Y is an input amount of a polyhydric alcohol, and Z is a production amount of a polyester polyol.)

The results of the quality evaluation and the recovery rate calculation for Examples 1 to 20 are summarized in Table 5 below.

[Table 5]

In addition, the results of the quality evaluation and the recovery rate calculation for Comparative Examples 1 to 20 are summarized in Table 6 below.

[Table 6]

Referring to Tables 5 and 6, the polyester polyols of Comparative Examples 1 to 20 using commercially available Dibutyltin dilaurate as a catalyst and the organotin recovered from the spent acid as catalysts, Lt; RTI ID = 0.0 &gt; 20 &lt; / RTI &gt; polyester polyols.

From the results of Examples 7 and 8 using a mixture of polycarboxylic acids, it was also confirmed that a polyester polyol could be synthesized without any problem even when one or more polycarboxylic acids were mixed and used. In Example 16 To 20, it was confirmed that a polyester polyol could be synthesized without any problem even when one or more polyhydric alcohols were mixed and used.

From the results of Example 9, it was also confirmed that polyester polyol could be synthesized without any problem even when a phthalic anhydride by-product generated in the production process of phthalic anhydride was used as a polycarboxylic acid.

Comparing the recovery rates of the examples and the comparative examples, it shows a high recovery rate of 94 to 96% in the case of the examples 1 to 20, while a recovery of 86 to 88% in the case of the comparative examples 1 to 20, It was confirmed that when the polyester polyol was synthesized at a relatively low temperature, the recovery rate could be significantly increased.

2 is a photograph of a polyester polyol prepared according to Example 1 and Comparative Example 1. Fig. Referring to FIG. 2, it was confirmed that the hue of the polyester polyol of Example 1 was brighter than that of Comparative Example 1. Thus, when a polyester polyol was synthesized at a relatively low temperature using a perovskite catalyst, It was confirmed that this improved polyester polyol with excellent quality could be synthesized.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that various modifications and changes may be made without departing from the scope of the present invention.

Claims (5)

(1) a step of obtaining a gel phase compound by mixing a metal precursor, which is a raw material of a perovskite catalyst, and citric acid;
(2) firing the obtained gel-like compound at a temperature of 600 to 1000 캜 to obtain a perovskite catalyst;
(3) 1 to 100 parts by weight of a polycarboxylic acid and 1 to 500 parts by weight of a polyhydric alcohol having a molecular weight of 40 to 55,000, and melting at 100 to 150 ° C .; and
(4) adding 0.0001 to 0.5 part by weight of the perovskite catalyst obtained as a molten mixture to the molten mixture at 160 to 210 ° C,
Wherein the perovskite catalyst is any one selected from the group consisting of LaMoO ₃ , MnMoO _3, and mixtures thereof.
The method according to claim 1,
The process for producing a polyester polyol according to claim 1, wherein the recovery rate of the polyester polyol is 90% or more.
[Equation 1]

(Wherein X is an input amount of a polycarboxylic acid, Y is an input amount of a polyhydric alcohol, and Z is a production amount of a polyester polyol.) The method according to claim 1,
The polyvalent carboxylic acid may be selected from the group consisting of phthalic anhydride, adipic acid, maleic anhydride, sebacic acid, citric acid, tartaric acid, terephthalic acid ), And mixtures thereof. &Lt; Desc / Clms Page number 24 &gt; The method according to claim 1,
Wherein the polyhydric alcohol is any one selected from the group consisting of alcohols represented by the following general formulas (2) to (4), and mixtures thereof.
(2)

(3)

[Chemical Formula 4]

(Wherein n is an integer of 1 to 100, and R ₁ and R ₂ are each H, a C ₁ to C ₁₈ hydrocarbon compound or a C ₁ to C ₁₈ hydroxyalkyl group.) The method according to claim 1,
The polyhydric alcohol may be at least one selected from the group consisting of diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, glycerol, pentaerythritol Wherein the polyester polyol is any one selected from the group consisting of Pentaerythritol, Sorbitol, Sucrose, and mixtures thereof.

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