KR20060070940A - Method for preparing copolyester resin using solid-phase polymerization - Google Patents

Abstract

The present invention relates to a method for producing a copolyester by using a solid phase polymerization method, comprising a esterification reaction and a polycondensation reaction of a dicarboxylic acid component containing terephthalic acid and a diol component containing 1,4-cyclohexanedimethanol. To obtain a copolyester prepolymer, which is characterized by crystallization and solid phase polymerization.

According to the present invention, by using a copolyester resin containing 50 to 100 mol% of 1,4-cyclohexanedimethanol based on the dicarboxylic acid component of the polyester, By performing the polymerization in two stages, it is possible to produce a crystallized chip state like the existing polyethylene terephthalate. That is, since there is no risk of fusion in the dryer during drying, drying is possible at a temperature higher than the glass transition temperature, and thus drying is possible within a short time under the desired moisture content, thereby obtaining a product having time and economic advantages in the process. .

1,4-cyclohexanedimethanol, polyester, ethylene glycol, terephthalic acid, drying method, crystallization, solid state polymerization

Description

Method for preparing copolyester using solid phase polymerization method {Method for preparing copolyester resin using solid-phase polymerization}

The present invention relates to a method for producing copolyester using solid phase polymerization. More specifically, the copolymerization polyester resin containing 1,4-cyclohexanedimethanol can be polymerized in two stages of melt polymerization and solid phase polymerization to produce crystallized chips through economical and efficient processes. It relates to a method for producing a copolyester using a solid phase polymerization method that can prevent the occurrence of fusion during molding.

Recently, co-polyester resins copolymerized with 1,4-cyclohexanedimethanol have become commercial polyesters used as important materials in the fields of packaging materials, molded articles, films, and the like. The polyester was initially prepared by adding 1,4-cyclohexanedimethanol during the transesterification reaction using dimethyl terephthalate, but recently, it was produced using terephthalic acid to improve economic efficiency and quality. You can get the result.

In this regard, U.S. Patent No. 6,342,579 discloses a high IV (Intrinsic Viscosity) copolymer polyester in the preparation of 1,4-cyclohexanedimethanol copolymerized polyester resin by only one step of melt polymerization. A method of preparing is introduced. According to the method, a copolyester having improved transparency and color is prepared by using a titanium compound as the polycondensation catalyst and a carboxy phosphonic acid compound as the stabilizer. However, in this case, the molding process must be dried at a temperature below the glass transition temperature, and therefore, there is a disadvantage in that dehumidification drying is performed for at least 6 hours in order to achieve the recommended moisture content of 500 ppm or less.

Therefore, the present invention solves the above-mentioned problems and researched to produce a product having properties superior to the copolymerized polyester resin according to the prior art, as a result, to produce a polyester resin copolymerized with 1,4-cyclohexanedimethanol It was found that by adding a two-stage process of solid-state polymerization after the one-stage polymerization process of melt polymerization, the process time during drying for the molding process can be significantly shortened, and the present invention was completed based on this.

Accordingly, an object of the present invention is to produce a conventional copolymerized polyester in a crystallized chip state through an economical and efficient drying process, as well as using a solid phase polymerization method that can prevent the occurrence of fusion during molding It is to provide a method for producing a copolyester.                         

Solid phase polymerization method of the copolyester according to the present invention for achieving the above object:

(a) a dicarboxylic acid component comprising (e) terephthalic acid, and (ii) 50 to 80 mol% of 1,4-cyclohexanedimethanol and 0 to 50 mol% of ethylene relative to the dicarboxylic acid component. Preparing a copolyester prepolymer by esterifying and polycondensing the diol component including glycol;

(b) crystallizing the copolyester prepolymer; And

(c) solid phase polymerizing the crystallized copolyester prepolymer;

Characterized in that it comprises a.

Here, the intrinsic viscosity of the copolymerized polyester prepolymer obtained in the step (a) is 0.5 ~ 0.6dl / g.

The crystallization step is carried out for 0.1 to 12 hours at a temperature of 130 ~ 190 ℃. In addition, the solid phase polymerization step is carried out for 1 to 96 hours under a temperature of 150 ~ 240 ℃ and reduced pressure of 10mmHg or less or inert gas stream.

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

As described above, in the present invention, in the preparation of the polyester resin copolymerized with 1,4-cyclohexanedimethanol, in addition to the melt polymerization step, the solid phase polymerization step may be additionally performed to produce a crystallized chip state, and dried in a dryer. In addition to reducing the time, there is provided a method for producing a copolyester resin excellent in moldability, which can solve the risk of fusion in the front zone (Feeding zone) of the molding machine.

According to the present invention, a copolyester prepolymer is prepared through a melt polymerization process performed during a conventional copolyester resin manufacturing process, and then crystallized and solid-phase polymerized to prepare a final copolyester resin.

The melt polymerization process can be thought of again divided into two steps, it is prepared through the first step of the esterification reaction and the second step of the polycondensation reaction as follows.

The first step, the esterification reaction may be carried out in a batch or continuous manner, and each raw material may be added separately, but it is most preferable to make a dicarboxylic acid component into a diol component in a slurry form. .

More specifically, first, a dicarboxylic acid component containing terephthalic acid and a diol component containing ethylene glycol and 1,4-cyclohexanedimethanol are reacted.

In this case, it is preferable to add the diol component to the dicarboxylic acid component so that the content of the diol component is 1.2 to 3.0, and to perform the esterification reaction under the conditions of 230 to 260 ° C and 1.0 to 3.0 kg / cm 2, but not limited thereto. It doesn't happen. Preferably, the said esterification temperature is 240-260 degreeC, More preferably, it is 245-255 degreeC. In addition, the esterification time is usually about 100 to 300 minutes, which may be appropriately changed depending on the reaction temperature, pressure and the molar ratio of the diol component to the dicarboxylic acid component used.

In addition to the terephthalic acid, the dicarboxylic acid component used for the purpose of improving the physical properties in the present invention isophthalic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, succinic acid, gluta Lactic acid, adipic acid, sebacic acid, 2,6-naphthalenedicarboxylic acid, and the like, but are not particularly limited thereto.

1,4-cyclohexanedimethanol used as one of the diol components is used to improve the moldability and other physical properties of the homopolymer, and cis-, trans- or a mixture of two isomers may be used. At this time, the amount of the 1,4-cyclohexane dimethanol is added to the amount close to the desired mole percent of the final polymer, preferably in the total glycol component in the range that can be crystallized in the polymer to enable solid phase polymerization It is good that it is 50-100 mol%.

In addition, ethylene glycol may be additionally used as the diol component, and the amount of the ethylene glycol may be used in an amount of 0 to 50 such that the total diol component is 100 mol% relative to the dicarboxylic acid in consideration of the amount of 1,4-cyclohexanedimethanol. It is good to be mol%.

In addition, other diol components usable in the present invention include 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,2-dimethyl-1,3-propanediol, 1,6-hexane Diols, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol and 1,3-cyclohexanedimethanol.

On the other hand, the esterification reaction does not require a catalyst, it is also possible to selectively add a catalyst in order to shorten the reaction time.

After the first step of the above-mentioned esterification reaction is completed, the second step of the polycondensation reaction is carried out. The polycondensation catalyst, stabilizer and colorant are generally used in the polycondensation reaction of the polyester resin. May optionally be used.

Polycondensation catalysts usable in the present invention include, but are not limited to, titanium, germanium and antimony compounds.

The titanium-based catalyst is generally used as a polycondensation catalyst of a polyester resin copolymerized with 1,4-cyclohexanedimethanol by 15% or more by weight of terephthalic acid, and even when a small amount is used in comparison with an antimony-based catalyst It is possible and also has the advantage of lower cost than germanium-based catalyst.

Titanium-based catalysts usable in the present invention include tetraethyl titanate, acetyltripropyl titanate, tetrapropyl titanate, tetrabutyl titanate, tetrabutyl titanate, polybutyl titanate, 2-ethylhexyl titanate, octylene Glycol titanate, lactate titanate, triethanolamine titanate, acetylacetonate titanate, ethyl acetoacetic ester titanate, isostearyl titanate, titanium dioxide, titanium dioxide and silicon dioxide co-precipitates, titanium dioxide and zirconium dioxide And coprecipitates.

In this case, since the amount of the polycondensation catalyst affects the color of the final polymer, the amount of polycondensation catalyst may vary depending on the desired color and the stabilizer and colorant used. Preferably, the amount of polycondensation catalyst is 1 to 100 ppm based on the amount of titanium based on the weight of the final polymer. More preferably, 1-50 ppm is good and 10 ppm or less is preferable based on a silicon element amount. At this time, if the amount of titanium element is less than 1ppm can not reach the desired degree of polymerization, if it exceeds 100ppm the color of the final polymer is yellow and the desired color cannot be obtained.                     

In addition, stabilizers and coloring agents and the like can be used as other additives.

Stabilizers usable in the present invention typically include phosphoric acid, trimethyl phosphate, triethyl phosphate, triethyl phosphonoacetate, and the like, and the amount of the stabilizer may be 10 to 100 ppm relative to the weight of the final polymer based on the small amount of people. At this time, if the addition amount of the stabilizer is less than 10ppm it is difficult to obtain the desired bright color, if it exceeds 100ppm there is a problem that does not reach the desired high polymerization degree.

In addition, the colorants usable in order to improve the color in the present invention include conventional colorants such as cobalt acetate and cobalt propionate, the addition amount is preferably 0 to 100ppm relative to the final polymer weight.

In addition to the colorant, conventionally known organic compounds may be used as the colorant.

On the other hand, the second condensation reaction is carried out after the addition of these components is preferably carried out under reduced pressure conditions of 260 ~ 290 ℃ and 400 ~ 0.1mmHg, but is not limited thereto.

The polycondensation step is carried out for the required time until the desired intrinsic viscosity is reached, the reaction temperature is generally 260 ~ 290 ° C, preferably 260 ~ 280 ° C, more preferably 265 ~ 275 ° C.

In addition, the polycondensation reaction is carried out under a reduced pressure of 400 ~ 0.1mmHg to remove the glycol as a by-product, and 1,4-cyclohexane with a IV (intrinsic viscosity) of 0.5 ~ 0.6dl / g to enable solid phase polymerization To prepare a polyester resin copolymerized with dimethanol.

Next, the copolyester resin prepared according to the method described above is crystallized for 0.1 to 12 hours at a temperature of 130 to 190 ℃.

In this case, when the crystallization process condition is out of the range, pellets stick to each other in the solid phase polymerization step, or the color is shifted to yellow due to high temperature, thereby reducing the product value.

Finally, the crystallized copolyester resin is prepared to have a intrinsic viscosity of about 0.75 to 0.80 dl / g by solid phase polymerization for 1 to 96 hours under a temperature of 150 to 240 ℃ and a reduced pressure of 10 mmHg or less or under an inert gas stream do.

At this time, when the reaction temperature is less than 150 ℃ there is a drawback of the reaction rate is very slow, if it exceeds 240 ℃ reaction rate is fast but the color is shifted to yellow, there is a risk that the commodity value falls.

In addition, when the reaction pressure exceeds 10mmHg, there is a risk that the value of the product is lowered due to the color shifted to yellow. For the same reason, when inert gases are used in the reaction, the purity should be at least 99%.

The copolyester resin of the present invention prepared according to the above-described method may be molded through a conventional molding process known in the art, and may be manufactured into a molded article having a suitable shape as needed.

Hereinafter, the present invention will be described in more detail with reference to the following examples and comparative examples, but the scope of the present invention is not limited thereto.

The physical properties shown in the following Examples and Comparative Examples were measured in the following manner:

◎ Dryer: Dry using a dehumidifying dryer manufactured by Motan

◎ Moisture content: measured using a moisture meter with Karl Fischer reagent

Example 1

Based on 6 moles of terephthalic acid, a polyester resin copolymerized with 562 g of 1,4-cyclohexanedimethanol and 354 g of ethylene glycol was mixed in a 3L reactor equipped with an outflow condenser while gradually raising the temperature to 255 ° C.

At this time, the generated water is discharged out of the system to ester reaction, and when the generation of water, the outflow is finished, the contents are transferred to a polycondensation reactor equipped with a stirrer, a cooling condenser and a vacuum system.

Add 0.5 g of tetrabutyl titanate to the esterification reaction, add 0.4 g of triethylphosphate, add 0.5 g of cobalt acetate, and increase the internal pressure from 240 ° C to 275 ° C. After 40 minutes of low vacuum reaction from atmospheric pressure to 50mmHg, ethylene glycol was removed and then slowly depressurized to 0.1mmHg, and reacted under high vacuum until the intrinsic viscosity of 0.55dl / g, which is the end point of the desired primary melt polymerization reaction, was discharged and chipped. Cut.                     

Hereinafter, the cut resin is crystallized at 150 ° C. for 5 hours, and then subjected to solid phase polymerization until the desired intrinsic viscosity is achieved at 220 ° C. and 1 mm Hg.

The moisture content measurement results of the drying temperature and time together with the reaction conditions are shown in Table 1 below.

Example 2

1,4-cyclohexane dimethanol was carried out in the same manner as in Example 1 except that 710 g of ethylene glycol and 291 g of ethylene glycol were added in the melt polymerization step. It is shown in Table 1 below.

Comparative Example 1

The polymer was prepared in the same manner as in Example 1 except that the solid phase polymerization step was not included, and the polymer was prepared by polymerization to have a desired high intrinsic viscosity in melt polymerization. The moisture content measurement results are shown in Table 1 below.

Comparative Example 2

Based on 6 moles of terephthalic acid, 277 g of 1,4-cyclohexanedimethanol and 476 g of ethylene glycol are copolymerized to produce high desired intrinsic viscosity in the melt polymerization step, except that the polymerization is carried out in the same manner as in Example 1. In addition, the moisture content measurement results according to the drying temperature and time together with the reaction conditions are shown in Table 1 below.

As can be seen through the examples and comparative examples, in the present invention, a solid-phase polymerization process was added to a conventional manufacturing process consisting of only melt polymerization when preparing a polyester resin copolymerized with 1,4-cyclohexanedimethanol. Due to this, risk factors such as fusion of products in the dryer such as existing products can be excluded, and therefore, the drying process can be performed at a temperature higher than the glass transition temperature. Accordingly, the drying time can be shortened, thereby improving the productivity during processing, and a phenomenon in which chips and the like are fused in the hopper of the molding machine can be significantly reduced, thereby improving moldability.

It is apparent that modifications and improvements are possible by those skilled in the art within the spirit or scope of the present invention. Accordingly, the simple modifications and variations of the present invention are all within the scope of the present invention, and the specific scope of protection of the present invention will be clarified by the appended claims and their equivalents.

Claims (5)

(a) a dicarboxylic acid component comprising terephthalic acid (iii), and (ii) 50 to 100 mol% of 1,4-cyclohexanedimethanol and 0 to 50 mol% of ethylene relative to the dicarboxylic acid component. Preparing a copolyester prepolymer by esterifying and polycondensing the diol component including glycol; (b) crystallizing the copolyester prepolymer; And (c) solid phase polymerizing the crystallized copolyester prepolymer; Method for producing a copolyester using a solid phase polymerization method comprising a. The method of claim 1, wherein the intrinsic viscosity of the copolymerized polyester prepolymer obtained in the step (a) is 0.5 ~ 0.6dl / g. The method of claim 1, wherein the crystallization step is performed at a temperature of 130 to 190 ° C. for 0.1 to 12 hours. The method of claim 1, wherein the solid phase polymerization step is prepared for the copolymerization polyester using a solid phase polymerization method, characterized in that carried out for 1 to 96 hours under a temperature of 150 ~ 240 ℃ and reduced pressure below 10mmHg or in an inert gas stream Way. A molded article formed by molding a polyester produced according to any one of claims 1 to 4.