KR20120100160A - Polyester resin prepared by using the urethane-modified polycarbonate polyol and method for preparing the same - Google Patents

Abstract

PURPOSE: A highly elastic polyester resin is provided to manufacture highly polyester resin with excellent flexability and moldability by using urethane-modified polycarbonate polyol with improved flexibility and moldability. CONSTITUTION: A highly elastic polyester resin comprises: a step of manufacturing urethane-modified polycarbonate polyol; a step of synthesizing polyester prepolymer consisting of carboxyl groups in both ends; and a step of manufacturing a polyester resin comprising the urethane-modified polycarbonate polyol by condensation-polymerizing the urethane-modified polycarbonate polyol and the polyester prepolymer. The comprised amount of the urethane-modified polycarbonate polyol is 10-50 weight% based on total weight of the resin.

Description

Highly elastic polyester resin prepared by using a urethane-modified polycarbonate polyol, and a method for preparing the same {Polyester Resin Prepared by Using the Urethane-Modified Polycarbonate Polyol and Method for Preparing the Same}

The present invention relates to a polyester resin having excellent flexibility and a method for manufacturing the same, and specifically, a urethane polyol and a polycarbonate diol are reacted to synthesize a urethane-modified polycarbonate polyol, and a polyester prepolymer having a carboxyl group at the end thereof is synthesized at a high temperature. The present invention relates to a method for producing a urethane-modified high elastic polyester resin by condensation polymerization reaction of two polymers.

Polyester resin composition is widely used for construction and industrial resin, and is most often used in PCM Panel, which is a building exterior material in construction.In the industrial automobile industry, primers for interior paints such as air cleaners, oil filters, wheels, bumpers, etc. It is used for intermediate paint.

Existing polyester resins used in building and industrial use is limited in chain extension due to the molecular structure of the dihydroxy compound and dicarboxylic acid compound has the disadvantage of inferior flexibility and formability. However, in recent years, flexibility and formability are simultaneously required to prevent cracking and peeling of the polyester resin coating film cured in a molding process of producing a part after coating a steel sheet, and thus improvement studies are being conducted.

In the present invention, to prepare a modified polycarbonate and to prepare a polyester resin having excellent elasticity by using the same, to improve the disadvantages of the above-described polyester resin.

An object of the present invention is to produce a high elastic polyester resin using a urethane-modified polycarbonate polyol with improved flexibility and moldability.

In order to solve the above problems, according to a preferred embodiment of the present invention, preparing a urethane-modified polycarbonate polyol; Synthesizing a polyester prepolymer composed of carboxyl groups at both ends; And condensing and polymerizing the urethane-modified polycarbonate polyol with the polyester prepolymer to produce a polyester resin including the urethane-modified polycarbonate polyol.

According to another suitable embodiment of the present invention, the urethane-modified polycarbonate polyol is characterized in that 10 to 50% by weight of the total weight of the resin.

According to another suitable embodiment of the present invention, the urethane-modified polycarbonate polyol is characterized in that it is prepared by reacting the polycarbonate polyol and urethane polyol at 70 ~ 90 ℃.

According to another suitable embodiment of the present invention, the urethane polyol is one or a mixture of two or more selected from the group consisting of isopron diisocyanate, hexamethylene diisocyanate, isocyanatocyclohexylmethane and diphenylmethane diisocyanate It is characterized by that.

According to another suitable embodiment of the present invention, there is provided a polyester resin prepared by the above-described method, having a number average molecular weight of 3,000 to 20,000 and having a structure of formula (1).

N is an integer of 1 to 30 in the above formula.

The high elastic polyester resin using the urethane-modified polycarbonate polyol of the present invention exhibits excellent properties in flexibility and formability as compared to conventional polyester resins. In particular, in the automotive parts or home appliance parts that the product is molded after coating the steel sheet can be usefully used as a paint for PCM paint and automotive paint which is excellent in formability and require flexibility.

1 to 3 are optical micrographs after the formability test of the coating film prepared by curing the high-elastic polyester resin prepared in the present invention.

Highly elastic polyester resin of the present invention, the first step of producing a urethane-modified polycarbonate polyol; A second step of synthesizing a polyester prepolymer composed of carboxyl groups at both ends; The hydroxy group of the urethane-modified polycarbonate polyol prepared in the first step and the carboxyl group of the polyester prepolymer prepared in the second step are combined with the urethane-modified polycarbonate polyol and polyester prepolymer through a condensation and polymerization reaction. It is prepared by a method comprising a third step of synthesizing a high elastic polyester resin.

First, the first step of preparing a urethane-modified polycarbonate polyol, a urethane polyol and a polycarbonate diol urethane polyol is produced by producing a urethane bond through a urethane reaction at 70 ~ 90 ℃. Polycarbonate diol is a compound containing a carbonate structure and excellent in flexibility and durability, it is mainly used as a raw material of high-grade polyurethane resin. It has a hydroxyl group at both ends of the molecular chain can be combined with the isocyanate group of the urethane polyol to form a urethane bond. Urethane polyols and polycarbonates are excellent in flexibility to prepare urethane-modified polycarbonate polyols in which two groups are connected by urethane bonds.

In the above urethane polyol, one or more selected from the group consisting of isopron diisocyanate, hexamethylene diisocyanate, isocyanatocyclohexylmethane and diphenylmethane diisocyanate may be used.

In the urethane-modified polycarbonate polyol prepared above, the content of urethane and polycarbonate diol is preferably 1: 2 in molar ratio.

The first step reaction is described by the following scheme 1.

[Reaction Scheme 1]

Looking at the reaction scheme 1, isoprone diisocyanate and a polycarbonate diol is a urethane polyol to produce a urethane-modified polycarbonate through a urethane reaction through a urethane reaction at 70 ~ 90 ℃. Wherein n is an integer from 1 to 30.

Next, to prepare a polyester prepolymer having a carboxyl group at the terminal (second step). A polyester prepolymer having a carboxyl group at its terminal is prepared by condensation and polymerization reaction at 150 to 250 ° C. by combining a dihydroxy compound and a dicarboxylic acid compound.

The polyester prepolymer may be prepared in various molecular weights through a combination of dihydroxy compound and dicarboxylic acid compound. At the time of ester bonding, the polymerization temperature is 150 ° C. or more, and condensation water is generated as the condensation reaction of the carboxyl group and the hydroxyl group proceeds. If the reaction temperature is 150 ° C or less, there is a problem that the condensation reaction does not occur smoothly. Therefore, to prepare the polyester prepolymer, the condensation reaction is performed for several hours at a high temperature of 150 to 250 ° C.

Examples of the dihydroxy compound include ethylene glycol, propylene glycol, butanediol, neopentyl glycol, hydroquinone, resorcinol, hydroxyphenyl, naphthalenediol, dihydroxydiphenyl ether, 1,6-hexanediol, 1,4 One selected from the group consisting of cyclohexanediol, 2,2-bis (4-hydroxyphenyl) propane, polycarbonatediol and diethoxylated bisphenol A, or polyoxyalkylene glycols and alkyl, alkoxy or halogen thereof -Substituted derivatives can be used alone or in combination of two or more selected from the above compounds.

As the dicarboxylic acid compound, terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl carboxylic acid, diphenyl ether dicarboxylic acid, diphenyl ethane dicarboxylic acid, cyclohexane dicarboxylic acid, One or a combination of two or more thereof selected from the group consisting of dific acid and sebacic acid, alkyl, alkoxy and halogen-substituted derivatives thereof can be used.

The second step reaction will be described by the following scheme 2.

Scheme 2

In the reaction scheme 2, 1,4-cyclohexyldiol, 1,6-hexanediol, neopentylglycol, phthalic anhydride, 1,4-cyclohexyldicarboxylic acid and adipic acid are condensation-polymerized, and the carboxyl group is terminated. To prepare a polyester prepolymer.

Finally, the third step is to combine the hydroxy group of the urethane-modified polycarbonate polyol prepared in the first step and the carboxyl group of the polyester prepolymer prepared in the second step through a condensation and polymerization reaction to a high elastic polyester This step is to synthesize the resin.

The third step is a condensation reaction step of the urethane-modified polycarbonate polyol and the polyester prepolymer, and the reaction temperature is controlled to be 180 to 220 ° C. during the condensation reaction. When the reaction temperature exceeds 220 ℃, since the decomposition of the polycarbonate diol occurs, a problem occurs in terms of reaction stability.

The urethane-modified polycarbonate diol in the third step is preferably 10 to 50% by weight relative to the total weight of the resin. If the urethane-modified polycarbonate diol is less than 10% by weight, there is a problem in that the flexibility and formability of the final synthetic high-elastic polyester resin is not good, and when it exceeds 50% by weight, the high-elastic polyester resin is poor in wettability with the material There is a problem that the adhesion is lowered.

The number average molecular weight of the high elastic polyester resin prepared above is 3,000 to 20,000.

Since the urethane-modified polycarbonate polyol has a hydroxy group at the terminal and the polyester prepolymer has a carboxyl group at the terminal, the urethane-modified polycarbonate polyol is subjected to condensation polymerization reaction of the dicarboxylic acid compound and the dihydroxy compound at a high temperature. Highly elastic polyester resins can be produced. Urethane-modified polycarbonate polyol has a long chain structure and a urethane bond in the molecular chain, unlike the raw materials of the conventional polyester resin can be expected excellent properties in terms of flexibility.

The third step reaction is described by the following scheme 3.

Scheme 3

The urethane-modified polycarbonate prepared in step 1 and a polyester prepolymer having a carboxyl group at the sock end were put in a reactor, and the temperature was raised to 150 ° C., followed by the step-up of temperature to 200 ° C. to carry out a condensation polymerization reaction, thereby providing a highly elastic polyester resin. To prepare. N is an integer of 1 to 30 in the above scheme.

The high elastic polyester resin using the urethane-modified polycarbonate polyol prepared in the present invention is excellent in flexibility and formability and can be used in various applications. The high-elastic polyester resin produced through the present invention includes a hydroxyl group, and it is also possible to cure at high temperature using a melamine curing agent and a block isocyanate curing agent.

Hereinafter, a highly elastic polyester resin using a urethane-modified polycarbonate polyol and a manufacturing method thereof according to embodiments of the present invention will be described in detail. However, the present invention is not limited only to the following embodiments, and may be implemented in various other forms.

<Production Example>

Preparation of Urethane Modified Polycarbonate Polyols

A four-necked flask with a volume of 500 mL was attached with a thermometer, condenser, stirrer and heating mantle, and the reaction was carried out under a nitrogen atmosphere. Urethane-modified polycarbonate polyol was prepared by putting 79.9 g of isoprone diisocyanate and 360.0 g of polycarbonate diol in a four-necked flask and heating it at 80 ° C. The completion of the urethane reaction was confirmed by measuring the absorbance of the infrared spectrophotometer.

Polyester Prepolymer Manufacturing

A four-necked flask of 500 mL was attached with a thermometer, condenser, stirrer and heating mantle. 29.2 g of adipic acid as a dicarboxylic acid compound, 76.9 g of phthalic anhydride, 103.2 g of 1,4-cyclohexyldicarboxylic acid, 41.6 g of neopentyl glycol as a dihydroxy compound, and 23.6 g of 1,6-hexanediol 69.6 g of 1,4-cyclohexyldiol was placed in a four neck flask. Then, the temperature was raised to about 150 ° C. under a nitrogen atmosphere, and the temperature was increased to 220 ° C. to condensation polymerization reaction of the dicarboxylic acid compound and the dihydroxy compound. Ester polypolymer was prepared.

Example 1

Capacity is 300 A 4 mL flask, mL, was attached with a thermometer, condenser, stirrer and heating mantle. 38.5 g of the urethane-modified polycarbonate polyol prepared in Preparation Example and 162.7 g of the polyester prepolymer prepared in Preparation Example were placed in a four-necked flask. The flask was heated to about 150 ° C. under a nitrogen atmosphere, and then stepped up to 200 ° C. to carry out a polymerization reaction of the dicarboxylic acid compound and the dihydroxy compound to remove condensed water generated in the reaction. The condensation reaction progress was observed by measuring the acid value using 0.1 N KOH solution, and when the acid value of the composite dropped to 5 or less, the reaction was terminated to prepare a high elastic polyester resin using a urethane-modified polyol.

Example  2

A four-necked flask of 300 mL was attached with a thermometer, condenser, stirrer and heating mantle. 60 g of the urethane-modified polycarbonate polyol prepared in the above preparation example and 139.3 g of polyester prepolymer were placed in a four-necked flask. The flask was heated to about 150 ° C. under a nitrogen atmosphere, and then stepped up to 200 ° C. to carry out a polymerization reaction of the dicarboxylic acid compound and the dihydroxy compound to remove condensed water generated in the reaction. The condensation reaction progress was observed by measuring the acid value using 0.1 N KOH solution, and when the acid value of the composite dropped to 5 or less, the reaction was terminated to prepare a high elastic polyester resin using a urethane-modified polyol.

Example  3

A four-necked flask of 300 mL was attached with a thermometer, condenser, stirrer and heating mantle. 83.6 g of the urethane-modified polycarbonate polyol prepared in the above preparation example and 121.1 g of polyester prepolymer were placed in a four-necked flask. The flask was heated to about 150 ° C. under a nitrogen atmosphere, and then stepped up to 200 ° C. to carry out a polymerization reaction of the dicarboxylic acid compound and the dihydroxy compound to remove condensed water generated in the reaction. The condensation reaction progress was observed by measuring the acid value using 0.1 N KOH solution. When the acid value of the composite drops below 5, the reaction is terminated to prepare a high elastic polyester resin using a urethane-modified polyol.

Comparative example  One

A four-necked flask of 500 mL was attached with a thermometer, condenser, stirrer and heating mantle. In a four-necked flask, 70 g of adipic acid and 120 g of isophthalic acid were added as a dicarboxylic acid compound, 115 g of neopentyl glycol and 35 g of trimethylol propane were added as a dihydroxy compound. The flask was heated to about 150 ° C. under a nitrogen atmosphere, and then stepped up to 220 ° C. to carry out a condensation polymerization reaction of the dicarboxylic acid compound and the dihydroxy compound. The reaction progress was observed by measuring the acid value using a 0.1 N KOH solution. When the acid value of the composite drops below 5, the reaction is terminated to prepare a polyester resin.

Evaluation of Physical Properties of Cured Coating Film

One) The tensile strength  Test

Methylated melamine (Cymel 303, Cytec) was added to the polyester resins prepared in Examples and Comparative Examples to form a cured coating film, and then tensile strength was evaluated. The thickness of the cured coating film was 400-500 micrometers, and it hardened | cured under 150 degreeC and 1 hour hardening conditions. Tensile strength was measured by applying the method of ASTM D 1822 in order to measure the flexibility of the cured coating film, the tensile strength evaluation results are shown in Table 1 below.

ASTM D 1822 is a method of measuring the tensile strength and elongation using a universal testing machine (UTM) after manufacturing a rectangular specimen for the cured coating film.

OH value T _g (℃) Tensile Strength (MPa) Elongation (%) Example 1 40 36 3.5 256 Example 2 60 25 1.9 502 Example 3 90 22 1.5 415 Comparative Example 1 85 52 25 38

Comparative Example 1 prepared a polyester resin of the same type except for the urethane-modified polycarbonate polyol, and showed a high tensile strength compared to the polyester resins prepared in Examples 1 to 3, but the elongation is 40% or less Low. In addition, in Table 1, the characteristics of the coating film cured polyester resin prepared by adjusting the content of the urethane-modified polyol of Examples 1 to 3, the glass transition temperature (T _{g) as} the content of the urethane-modified polyol increases ) Tends to decrease.

Example 2 has the best elongation of 500% or more, but in the case of Example 3, the higher the urethane-modified polycarbonate polyol content, the lower the elongation to 415% and the lower the tensile strength. Thus, Example 2 Urethane-modified polycarbonate polyol 30% by weight It was confirmed that the high elastic polyester resin used was the best.

2) formability test

Methylated melamine (Cymel 303, Cytec) was added to the polyester resins prepared in Examples and Comparative Examples, and then coated on a 0.8 mm steel sheet and cured at 220 ° C. for 60 seconds. The thickness of the cured coating film is 20 ~ 25㎛, the drawing test was performed to measure the moldability of the cured coating film. In the drawing test, a 48 mm high, 50 mm x 50 mm square shape was formed into a shape, and the forming speed was 17 mm / s. After the drawing test, the degree of breakdown and peeling of the coating film was magnified and observed through an optical microscope at 160 times.

As shown in Table 2, there was no cured coating breakage and peeling phenomenon in the visual evaluation, but in the optical microscope evaluation, there was a coating breakage and peeling phenomenon in Examples 1 and 3, and in Example 2, good results were obtained. Therefore, it was confirmed that the high elastic polyester resin when the urethane-modified polyol of Example 2 was used at 30% by weight showed the most excellent physical properties.

Visual evaluation Optical microscopy Example 1 clear Cracks and Peeling Occurred Example 2 clear No cracks and peeling Example 3 clear Cracks and Peeling Occurred

Claims (5)

Preparing a urethane-modified polycarbonate polyol;
Synthesizing a polyester prepolymer composed of carboxyl groups at both ends; And
Condensing and polymerizing the urethane-modified polycarbonate polyol and the polyester prepolymer to produce a polyester resin comprising a urethane-modified polycarbonate polyol. The method according to claim 1,
The urethane-modified polycarbonate polyol is a method for producing a high elastic polyester resin, characterized in that 10 to 50% by weight relative to the total weight of the resin. The method according to claim 1,
The urethane-modified polycarbonate polyol is a method for producing a high elastic polyester resin, characterized in that the polycarbonate polyol and urethane polyol is prepared by reacting at 70 to 90 ℃. The method according to claim 3,
The urethane polyol is a high-elastic polyester resin, characterized in that one or a mixture of two or more selected from the group consisting of isopron diisocyanate, hexamethylene diisocyanate, isocyanatocyclohexylmethane and diphenylmethane diisocyanate Way. A high elastic polyester resin prepared by the method of claim 1, having a number average molecular weight of 3,000 to 20,000, and having the structure of Formula 1.
[Formula 1]

(Where n is an integer of 1 to 30).

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