KR20060071710A - Polyester resin copolymerized with neopentylglycol having low oligomer content and preparing method thereof - Google Patents

Abstract

The present invention relates to a polyester resin copolymerized with neopentylglycol having a low content oligomer and a method for preparing the same, wherein the diol component comprising an acid component and neopentylglycol is subjected to an esterification reaction and a polycondensation reaction, followed by water treatment ( It is characterized by a solid state polycondensation reaction after crystallizing the amorphous resin using a water treatment process.

According to the present invention, in addition to the conventional solution polymerization of the amorphous copolyester, the oligomer content of the resin can be drastically reduced by undergoing crystallization and solid-phase polycondensation through water treatment, thereby injection molding using the copolyester resin. In the case of manufacturing a molded article through extrusion molding or thermoforming, defects in the molding process due to oligomers can be greatly reduced, thereby increasing molding productivity.

Water treatment process, solid state polymerization process, neopentyl glycol, ethylene glycol, terephthalic acid, oligomer

Description

Polyester resin copolymerized with neopentylglycol having a low content oligomer and a method for preparing the same {Polyester resin copolymerized with neopentylglycol having low oligomer content and preparing method

The present invention relates to a polyester resin copolymerized with neopentylglycol having a low content oligomer and a method for producing the same. More specifically, in a polyester resin containing 20 to 35 mol% of neopentylglycol in the diol component, a polymorph modified to have a low oligomer content by introducing a crystallization process using water treatment, in addition to the usual melt polymerization, to have a low oligomer content. An ester resin and its manufacturing method are related.

Polyester is environmentally friendly and does not contain harmful substances to humans, and has been widely used in fields such as juices, soft drinks, carbonated beverage filling containers and packaging materials, molded products, sheets, films, and the like.

Representative examples thereof include polyethylene terephthalate, which is a crystalline resin in which crystallization occurs by heat or stretching, and examples of such crystalline polyesters include polyethylene terephthalate (PET) and polyethylene described above. Naphthalate (PEN), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polycyclohexylenedimethylene terephthalate (PCT), polycyclohexylenedimethylene cyclohexyldicarboxylate ( PCCD) etc. can be mentioned.

Such crystalline resins have a disadvantage in that cooling is insufficient during molding, or when molding to a thick thickness, clouding occurs due to crystallization and transparency is greatly reduced. Accordingly, in order to prevent the clouding phenomenon due to the above-mentioned crystallization, the polyester modified by lowering the crystallization rate of the resin itself so that crystallization does not occur under general molding conditions may be classified as amorphous polyester.

It is necessary to distinguish between crystalline polyesters and amorphous polyesters here. In general, it is possible to visually determine whether crystallization occurs by heating the resin below the melting point. In addition, it can be classified by the molar ratio of the raw materials used to polymerize the polyester, depending on the degree of co-condensation of additional glycol or dicarboxylic acid to the main glycol or dicarboxylic acid, that is, depending on the degree of modification of the polyester Is determined. In general, when the main glycol is modified with at least 15 to 20 mol% of glycol, or the main dicarboxylic acid with at least 15 to 20 mol% of dicarboxylic acid, it may be regarded as an amorphous polyester having a slow crystallization rate. Of course, when the glycol or derivative thereof and dicarboxylic acid or derivative thereof is an isomer, crystallinity may also be determined depending on the ratio of cis and trans forms of the isomer.

In addition, resins that do not exhibit crystallization peaks can be classified as amorphous resins by testing with the differential scanning calorimetry test method. As described in US Pat. No. 5,633,340, light transmittance over time when crystallized at a specific temperature is described. It can also be divided into the Crystallization haze half-time until the reduction is 50%.

Such crystalline polyesters and amorphous polyesters also differ in the method for their preparation. The crystalline polyesters are obtained by esterifying dicarboxylic acids or their ester-forming derivatives with glycols or their ester-forming derivatives, followed by liquid phase polycondensation reactions. After forming a particulate polyester through the pre-crystallization it is crystallized by heat, and then through a series of processes to perform a solid phase polymerization to increase the degree of polymerization under an inert gas atmosphere or reduced pressure to obtain the desired intrinsic viscosity.

On the other hand, in the case of amorphous polyester resin, dicarboxylic acid or its ester forming derivative and glycol or its ester forming derivative are prepared by performing only esterification reaction and liquid polycondensation reaction. In other words, unlike the process of preparing a crystalline polyester in general, the pre-crystallization and solid-phase polymerization process can not be carried out to reach the target intrinsic viscosity only through the esterification reaction and liquid phase polycondensation reaction.

Commercially produced neopentyl glycol copolymerized polyester resins can also distinguish crystalline polyesters from amorphous polyesters in this way. Commercially produced polyester resins copolymerized with neopentyl glycol are generally prepared using terephthalic acid as a main component as a dicarboxylic acid component and neopentyl glycol and ethylene glycol as main components as a diol component. Of these, polyesters containing neopentyl glycol in less than 20 mol% of diol components are polymerized through solid phase polymerization as crystalline polyesters, and are widely used as beverage filling containers for juices, soft drinks, and carbonated drinks.

Meanwhile, polyesters containing 20 mol% or more of neopentyl glycol in the form of amorphous polyester are impossible to solidify and polymerize to a desired intrinsic viscosity only by melt polymerization, and are used for injection molded articles, packaging materials, sheets, films, etc. Commercially available.

In particular, modified polyesters containing terephthalic acid as the main dicarboxylic acid component and containing 20 to 35 mol% of neopentyl glycol in the diol component are difficult to crystallize by heat, and thus can be polymerized only through melt polymerization. Alternatively, the solid phase polymerization reacted under reduced pressure may not be performed, and the low molecular weight reaction byproducts may not be removed to the outside of the resin. As a result, the content of reaction by-products such as oligomers and acetaldehydes contained in the resin is increased, and in particular, since the polymer has a high content of oligomers, a molded article is produced by injection molding, extrusion molding or thermoforming using an amorphous polyester resin. The oligomers adhere to the mold inner surface, the gas exhaust pipe, the exhaust pipe, or the like of the mold, or stick to the extrusion roll to cause mold contamination or roll contamination. Here, the oligomer generally refers to a low polymer having a molecular weight of 3000 or less having a small repeating unit made in polymer polymerization. If contamination occurs, the surface of the molded product may be rough or white, and the extruded sheet or film may be detached from the roll, causing defects. Therefore, the contamination may need to be frequently removed. .                         

In practice, oligomers in polyester melt polymerization are known as equilibrium reactions (Walker GR, Semlyen JA. Polymer 1970, 11 , 472, cooper DR, Semlyen JA. Polymer 1973 14 , 185). Accordingly, the polyester prepared by melt polymerization necessarily includes oligomers at a constant equilibrium value, and is particularly copolymerized according to a conventional method for preparing amorphous polyester to copolymerize neopentyl glycol containing 20 to 35 mol% of diol components. In the case of polyester, there is an urgent need for a method that can solve the problem of a decrease in molding productivity due to such high oligomers inevitably generated during melt polymerization.

In view of the above situation, the inventors of the present invention provide a method for solid phase polymerization by crystallizing a modified polyester resin containing 20 to 35 mol% of dipent components, which is difficult to crystallize through heat treatment. As a result of extensive research, it has been found that the amorphous resin can be crystallized through the water treatment process and that the solid phase polymerization can be carried out using the same, and the present invention has been completed based thereon.

Accordingly, an object of the present invention is to modify the polyester resin containing 20-35 mol% of neopentyl glycol in the diol component, by crystallizing through water treatment to enable additional solid phase polymerization in addition to the usual esterification reaction and liquid polycondensation reaction. It is to provide a modified polyester resin having a low content oligomer and excellent moldability and a method for producing the same.                         

According to an aspect of the present invention for achieving the above object:

In a polyester resin obtained by copolymerizing an acid component of dicarboxylic acid or ester forming derivative thereof and a diol component of glycol or ester forming derivative thereof,

The diol component comprises 20 to 35 mol% of neopentyl glycol, the low content oligomer, characterized in that the polyester resin has an oligomer content of less than 0.31% GPC (Gel Permeation Chromatography) oligomer area percentage There is provided a polyester resin copolymerized with neopentylglycol having:

Here, the GPC oligomer area ratio% is a value representing the area occupied by the oligomer to the total area (polymer area + oligomer area) of the polyester resin using GPC as an area ratio%, wherein the oligomer is a polymer having a molecular weight of 3000 or less. The polymer means a polymer having a molecular weight of 3000 or more.

According to another aspect of the present invention for achieving the above object:

In the manufacturing method of the copolymer polyester which consists of the acid component which consists of dicarboxylic acid or its ester forming derivative, and the diol component which consists of glycol or its ester forming derivative,

(a) esterifying and liquid polycondensation of a diol component comprising an acid component and 20 to 35 mole% of neopentyl glycol;

(b) crystallizing the polycondensation reactant by contacting water or steam at 60 to 130 ° C. for 30 minutes to 10 hours; And                         

(c) heating the crystallization to a temperature below the melting point to perform a solid phase condensation reaction;

Provided is a method for producing a polyester resin copolymerized with neopentyl glycol having a low content oligomer comprising a.

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

As described above, in the case of the copolymer polyester containing 20 to 35 mol% of neopentyl glycol in the diol component, since it is difficult to crystallize conventionally and achieves the desired intrinsic viscosity only by melt polymerization, it is inevitably high in the copolymerized polyester resin. In the present invention, in addition to the conventional oligomer and liquid phase polycondensation reaction, the resin is crystallized by crystallizing the amorphous polyester resin through a water treatment process to enable solid phase polymerization. Polyester resin copolymerized with neopentylglycol having a low content oligomer, which can significantly reduce the content of oligomers, thereby preventing adverse effects of oligomers on the molding process during molding of the polyester resin A method is provided.

The polyester resin according to the present invention copolymerizes an acid component of dicarboxylic acid or an ester-forming derivative thereof and a diol component of glycol or an ester-forming derivative thereof according to conventional melt polymerization, followed by an amorphous resin through a water treatment process. After crystallization, it is prepared by solid phase polymerization again.                     

The melt polymerization process can be thought of again divided into two steps, it is carried out 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 performed in a batch or continuous manner, and each raw material may be added separately, but it is most preferable to make an acid component into a diol component in a slurry form.

More specifically, first, an acid component containing terephthalic acid and a diol component containing neopentyl glycol are reacted.

At this time, the content of the diol component with respect to the acid component is added in a molar ratio of 1.1 to 3.0 and the esterification reaction is carried out under the conditions of 200 to 320 ℃ and 1.0 to 3.0 kg / ㎠.

The acid component used in the present invention essentially includes terephthalic acid as a main component, and isophthalic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid as other dicarboxylic acids for physical properties and the like. And aromatic dicarboxylic acids having 8 to 14 carbon atoms and aliphatic dicarboxylic acids having 4 to 12 carbon atoms can be used.

The acid component preferably contains 80 to 100 mol% of terephthalic acid and 0 to 20 mol% of other dicarboxylic acids to most effectively obtain the desired physical property improving effect.

The diol component used in the present invention includes neopentyl glycol and ethylene glycol. The amount of neopentyl glycol is preferably 20 to 35 mol% for improving moldability and other physical properties of homopolymers consisting of terephthalic acid and ethylene glycol, and the amount of ethylene glycol is used in consideration of the amount of neopentyl glycol. The sum is preferably 65 to 80 mol% so that the sum is 100 mol%.

In addition, other diol components usable in the present invention include diethylene glycol, triethylene glycol, propanediol, pentanediol, hexanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol and tetramethylcyclo Butanediol etc. are contained, It is preferable that the usage-amount is 20 mol% or less.

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 esterification reaction is completed, the second step of the polycondensation reaction is carried out. Before the start of the second polycondensation reaction, a polycondensation catalyst and a stabilizer may be added to the esterification reacted beforehand, and a colorant may be added together if necessary.

The polycondensation catalyst may be appropriately selected from titanium, germanium, antimony and aluminum-based compounds, and the amount of the polycondensation catalyst is preferably 0.1 to 500 ppm based on the amount of metal elements relative to the weight of the final polymer, but affects the color of the final polymer. The amount used depends on the desired color, stabilizer and colorant used.

Phosphoric acid, trimethyl phosphate, triethyl phosphate, triethyl phosphonoacetate, and the like may be used as the stabilizer, and the amount of the stabilizer is preferably 0.1 to 500 ppm relative to the weight of the final polymer based on the small amount of people. The stabilizer may also be added before the esterification reaction.                     

In addition, a colorant may be used to improve the color of the final resin, and examples thereof include conventional colorants such as cobalt acetate and cobalt propionate, and the amount thereof is suitably 1 to 500 ppm relative to the weight of the final polymer. Do.

The second step, which is the polycondensation step, is typically performed under reduced pressure of 200 to 320 ° C and 400 to 0.1 mmHg. The polycondensation step is carried out for the required time until the desired intrinsic viscosity is reached, the reaction temperature is preferably 260 ~ 320 ℃, preferably 265 ~ 285 ℃. In addition, the polycondensation reaction is carried out under a reduced pressure of 400 ~ 0.1mmHg to remove the glycol as a by-product.

The amorphous polyester resin thus obtained is quenched with water, cut into particulates, and then transferred to the next step.

According to the present invention, in addition to the first step of the esterification reaction and the second step of the polycondensation reaction, the third step of the crystallization process through water treatment, and the crystallization is heated to a temperature below the melting point in an inert atmosphere or reduced pressure A fourth step of solid phase polymerization reaction is added. Therefore, even if the intrinsic viscosity achieved by the above-described second step is set lower than the general case, the desired higher intrinsic viscosity can be obtained through the subsequent two-step additional process.

The third step of the crystallization process is carried out by contacting the particulate polycondensation reactant with water or steam at a temperature of 60 to 130 ° C., preferably 70 to 110 ° C. for 30 minutes to 10 hours. At this time, if the crystallization temperature is less than 60 ℃ there is a problem that the crystallization time is too long, if it exceeds 130 ℃ is too high than most of the polyester glass transition temperature, there is a risk of fusion even if strong stirring.

In the contacting process, a stirring process may be required to prevent fusion of the polycondensate depending on the contacting method and form, and the rate of crystallization may vary according to the degree of modification of the polycondensation reactant, and the crystallization process time by water treatment This may vary.

Crystallization by the water treatment of the amorphous polyester is a unique phenomenon found by the present inventors, the water used can be easily removed in the polymer through methods such as general dehydration and polymer drying.

In addition, in order to further increase the crystallinity and the melting temperature of the crystals, the particulate polyester crystallized through water treatment may be additionally subjected to a process step of crystallizing by heat, and if necessary, such additional crystallization step may be included in the process. The polyester particles crystallized through the water treatment can increase the melting temperature of the crystals through this additional crystallization step of gradually increasing the temperature because the melting temperature of the crystal is low, thereby minimizing the fusion in the subsequent solid-phase polymerization step, at a high solid phase temperature It can react to speed up the solid phase.

Finally, the fourth step of the solid phase polymerization process is a temperature below the melting point, preferably 150 to 240 ℃, more preferably 180 to 230 ℃ of the particulate polyester crystallized through a water treatment process or an additional heat crystallization step Heating is carried out in a normal inert gas atmosphere such as nitrogen gas, argon gas, carbon dioxide gas or the like under normal pressure or under reduced pressure of 400 to 0.1 Torr. As said inert gas, nitrogen gas is especially preferable.

On the other hand, in order to prevent molecular weight decrease by hydrolysis before the solid phase polymerization reaction, the dehydration and drying process of the particulate polyester may be further performed as necessary.

The polyester resin of the present invention prepared according to this method has an intrinsic viscosity of about 0.3 to 2.0 dl / g, and is about 80% or less with respect to the amount of oligomer present in the resin polymerized using only melt polymerization according to the prior art. When the oligomer of is contained, it demonstrates in detail below.

Usually, the oligomer content contained in the resin after copolymerization changes depending on the amount of neopentyl glycol used as the diol component of the polyester resin. Here, when the polyester resin is prepared by melt polymerization using only an acid component containing terephthalic acid and a diol component containing 20 to 35 mol% of neopentyl glycol according to the prior art, the amount of equilibrium oligomer produced at this time is The percentage of gel permeation chromatography (GPC) is about 0.38% or more. As described above, moldability is poor due to the inclusion of a relatively high content of oligomer.

In this case, the GPC area ratio% is a value representing the area occupied by the oligomer with respect to the total area (polymer area + oligomer area) of the polyester resin using GPC as an area ratio%, wherein the oligomer means a polymer having a molecular weight of 3000 or less. The polymer means a polymer of more than 3000.                     

On the other hand, as a measuring method for expressing the amount (%) of the oligomer by GPC area ratio, the polyester resin is dissolved in a mixed solution of ortho-chlorophenol and chloroform in a volume ratio of 1: 3, and then the refractive index in a 40 ℃ thermostat After measuring the GPC by the detector, it is most preferable to calculate the ratio of the area of the oligomer part to the total area by calculating the area of the polymer part and the oligomer part, but the present invention is not particularly limited thereto. It can be performed according to a known method.

Accordingly, in the present invention, the content of the oligomer in the resin is 0.31% (GPC area ratio%) by crystallizing the amorphous polyester resin through a water treatment process to enable solid phase polymerization in addition to the normal esterification reaction and the liquid polycondensation reaction as described above. Significantly reduced)

The polyester resin according to the present invention has a reduced oligomer content by at least about 20% compared to a polyester resin polymerized only by melt polymerization according to the prior art when contrasting based on resins having the same neopentylglycol content.

That is, the polyester resin of the present invention has an oligomer content of about 80% or less, preferably about 50 to 70%, based on 100% of the oligomer present in the polyester resin of the prior art.

The copolyester resin of the present invention described above is used in oligomers because it contains a low content of oligomer in the manufacture of a molded product of a suitable shape as needed through conventional injection molding, extrusion molding or thermoforming known in the art. It is possible to greatly reduce the defects in the molding process, thereby improving the molding productivity.

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

Unless stated otherwise in the following Examples and Comparative Examples, the unit "parts" means "parts by weight". In addition, the physical properties shown in the following Examples and Comparative Examples were measured by the following method.

◎ Intrinsic Viscosity (IV): After dissolving in 150 ° C ortho-chlorophenol at a concentration of 0.12%, it is measured using a Ubelrod viscometer in a 35 ° C thermostat.

◎ Gel Permeation Chromatography (GPC) oligomer content: After dissolving in ortho-chlorophenol and chloroform volume 1: 3 mixture, measuring gel permeation chromatography (PL220 model) using a refractive index detector in a 40 ℃ thermostatic chamber, and then polymer part and oligomer The area of a part is calculated and measured by the ratio calculation of the area of an oligomer part to the total area.

Example 1

1242 parts of terephthalic acid, 156 parts of neopentylglycol, 836 parts of ethylene glycol, and phosphorus stabilizer were added to 80 ppm relative to the amount of the final polymer in a small amount of the reactor, and the pressure was 2.0 kg / After raising to 2 cm 2, the temperature of the reactor is gradually raised to 255 ° C. to react. At this time, the generated water is discharged out of the system and esterified. When the generation and outflow of water are completed, the reactant is transferred to a polycondensation reactor equipped with a stirrer, a cooling capacitor, and a vacuum system. Titanium-based catalyst is added to the esterification reactant to be 55 ppm relative to the final polymer amount based on the titanium element amount, and cobalt-based colorant is added to 100 ppm to the final polymer amount based on the cobalt element amount, and the internal temperature is 240 While raising the pressure from ℃ to 275 ℃, the ethylene glycol was first removed from the vacuum at 50 mmHg for 40 minutes at low pressure, and then slowly decompressed to 0.1mmHg until the desired intrinsic viscosity was reached under high vacuum. While ejecting it, cut it into chips.

The neopentyl glycol copolyester resin thus prepared was put in distilled water, boiled at 100 ° C. for 2 hours to crystallize, and then dried in a 70 ° C. hot air dryer for 2 hours.

Next, 200 g of granulated crystallized polyester resin was put in a 1 L solid-phase reactor through which nitrogen passes from the bottom to the top, and gradually increased from 160 ° C. to 210 ° C. at a rate of 10 ° C. per hour, followed by solid phase at 210 ° C. for 15 hours. A condensation reaction was performed. As a result of quantitative analysis of the mole ratio of total neocarboxylic acid to neopentyl glycol copolymerized polyester resin using ¹ H-NMR, terephthalic acid 100 mol%, neopentyl glycol 20 mol%, ethylene glycol 78 mol% , Diethylene glycol was confirmed to be composed of a ratio of 2 mol%. In addition, the intrinsic viscosity and oligomer content of the obtained polyester was measured as described above, and the results are shown in Table 1 below.

Example 2

1224 parts of terephthalic acid, 207 parts of neopentylglycol, 836 parts of ethylene glycol, and phosphorus stabilizer were added in a 3L reactor equipped with a stirrer and an outlet condenser such that 80 ppm of the final polymer amount was added, and the pressure was adjusted to 2.0 kg / After raising to 2 cm 2, the temperature of the reactor is gradually raised to 255 ° C. to react. At this time, the generated water is discharged out of the system and esterified. When the generation and outflow of water are completed, the reactant is transferred to a polycondensation reactor equipped with a stirrer, a cooling condenser, and a vacuum system. Titanium-based catalyst is added to the esterification reactant to be 55 ppm relative to the final polymer amount based on the titanium element amount, and cobalt-based colorant is added to 100 ppm to the final polymer amount based on the cobalt element amount, and the internal temperature is 240 While raising the pressure from 2 ℃ to 275 ℃, remove the ethylene glycol with low vacuum reaction at 50mmHg for 40 minutes at first pressure and then slowly depressurize to 0.1mmHg until the desired intrinsic viscosity is reached under high vacuum. While discharging it and cutting it into chips.

The neopentyl glycol copolyester resin thus prepared was put in distilled water, boiled at 100 ° C. for 2 hours to crystallize, and dried in a 70 ° C. hot air dryer for 1 hour.

Next, 200 g of granular crystallized polyester resin was put into a 1 L solid-phase reactor through which nitrogen passes from the bottom to the top, and gradually increased from 160 ° C. to 210 ° C. at a rate of 10 ° C. per hour, followed by solid phase at 210 ° C. for 15 hours. A condensation reaction was performed.                     

As a result of measuring the molar ratio of the total dicarboxylic acid to neopentyl glycol copolymerized polyester resin thus prepared using ¹ H-NMR, terephthalic acid 100 mol%, neopentyl glycol 27 mol%, ethylene glycol 71 mol%, It was confirmed that the ratio of diethylene glycol 2 mol%. In addition, the intrinsic viscosity and oligomer content of the obtained polyester was measured, and the results are shown in Table 1 below.

Comparative Example 1

Of Example 1, and the same circle and additives In the esterification reaction in the same reactor, and then it proceeds until it reaches the liquid condensation reaction to the target intrinsic viscosity and then to discharge it to cut into a chip to complete the polymerization ¹ H- As a result of quantitative analysis of the molar ratio of the total dicarboxylic acid using NMR, it was confirmed that the ratio of the molar ratio of terephthalic acid 100 mol%, neopentyl glycol 20 mol%, ethylene glycol 78 mol%, diethylene glycol 2 mol%. . In addition, the intrinsic viscosity and oligomer content of the obtained polyester was measured, and the results are shown in Table 1 below.

Comparative Example 2

Example 2 in the same manner in the same reactor and with the source and additives In the esterification reaction, and then proceeds until the desired intrinsic viscosity in the liquid phase polycondensation reaction and then to discharge it to cut into a chip to complete the polymerization ¹ H- As a result of measuring the molar ratio of the total dicarboxylic acid using NMR, it was confirmed that the molar ratio of terephthalic acid was composed of 100 mol%, neopentyl glycol 27 mol%, ethylene glycol 71 mol%, and diethylene glycol 2 mol%. . In addition, the intrinsic viscosity and oligomer content of the obtained polyester was measured, and the results are shown in Table 1 below.

division Intrinsic viscosity (dl / g) Oligomer content (% of GPC area) Example 1 0.75 0.29 Example 2 0.77 0.28 Comparative Example 1 0.74 0.42 Comparative Example 2 0.76 0.39

As can be seen from the above examples and comparative examples, according to the present invention, it is possible to crystallize the amorphous polyester resin containing 20 to 35 mol% of neopentyl glycol in the diol component through water treatment to enable solid phase polymerization. there was.

In addition, the oligomer content (GPC area ratio) in the resin of the polyester resins prepared to have the same neopentyl glycol content according to the method of the present invention and the prior art and having a similar intrinsic viscosity, according to the present invention, It was found that the polyester resin has an oligomer content of at least 20% lower than that of the polyester resin according to the prior art.

When injection molding, extrusion molding, or thermoforming of a resin having a small oligomer content is carried out, oligomers are attached to the inner surface of the mold, the gas exhaust pipe, the exhaust pipe of the mold, or stick to the extrusion roll to cause mold contamination or roll contamination. It is reduced, the production of the molded article is rarely stopped in order to remove the oligomer attached to the mold and the roll has the advantage that the productivity of the molded article is greatly improved.

In addition, there is no need to reach the target intrinsic viscosity in the melt polymerization at once, there is an advantage that the melt polymerization time is shortened. In addition, high melt viscosity special melt polymerization equipment to achieve high intrinsic viscosity is eliminated, and even in the melt polymerization equipment used in general polyethylene terephthalate process, neopentyl glycol is 20 ~ 35 mol% copolymerized polyester resin in glycol Since it becomes possible to superpose | polymerize, productivity improvement can be expected.

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 (13)

In a polyester resin obtained by copolymerizing an acid component of dicarboxylic acid or ester forming derivative thereof and a diol component of glycol or ester forming derivative thereof, The diol component comprises 20 to 35 mol% of neopentyl glycol, the low content oligomer, characterized in that the polyester resin has an oligomer content of less than 0.31% GPC (Gel Permeation Chromatography) oligomer area percentage Polyester resin copolymerized with neopentyl glycol having: Here, the GPC oligomer area ratio% is a value representing the area occupied by the oligomer to the total area (polymer area + oligomer area) of the polyester resin using GPC as an area ratio%, wherein the oligomer is a polymer having a molecular weight of 3000 or less. Means the polymer means a polymer having a molecular weight of more than 3000. The method of claim 1, wherein the GPC area ratio is dissolved in the polyester resin in a mixed solution of ortho-chlorophenol and chloroform in a volume ratio of 1: 3, and then measured by GPC with a refractive index detector in a 40 ° C thermostat, A polyester resin copolymerized with neopentylglycol having a low content oligomer, characterized by calculating the area of the oligomer portion and calculating the proportion of the area of the oligomer portion to the total area. The acid component according to claim 1, wherein the acid component comprises (i) 80 to 100 mol% of terephthalic acid, and (ii) isophthalic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, and 8 carbon atoms. Neopentyl having a low content oligomer comprising 0-20 mol% of other dicarboxylic acids selected from the group consisting of aromatic dicarboxylic acids having ˜14 and aliphatic dicarboxylic acids having 4-12 carbon atoms. Polyester resin copolymerized with glycol. The diol component according to claim 1, wherein the diol component comprises (i) 20 to 35 mol% of neopentyl glycol, (ii) 65 to 80 mol% of ethylene glycol, and (iii) diethylene glycol, triethylene glycol, propanediol, and pentanediol. Low olefin oligomer comprising 0-20 mol% of other glycols selected from the group consisting of hexanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol and tetramethylcyclobutanediol A polyester resin having neopentyl glycol having a copolymer. The polyester resin copolymerized neopentylglycol having a low content oligomer according to claim 1, wherein the intrinsic viscosity of the polyester is 0.3 to 2.0 dl / g. In the manufacturing method of the copolymer polyester which consists of the acid component which consists of dicarboxylic acid or its ester forming derivative, and the diol component which consists of glycol or its ester forming derivative, (a) esterifying and liquid polycondensation of a diol component comprising an acid component and 20 to 35 mole% of neopentyl glycol; (b) crystallizing the polycondensation reactant by contacting water or steam at 60 to 130 ° C. for 30 minutes to 10 hours; And (c) heating the crystallization to a temperature below the melting point to perform a solid phase condensation reaction; Method for producing a polyester resin copolymerized neopentyl glycol having a low content oligomer, characterized in that it comprises a. The acid component according to claim 1, wherein the acid component comprises (i) 80 to 100 mol% of terephthalic acid, and (ii) isophthalic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, and 8 carbon atoms. Neopentyl having a low content oligomer comprising 0-20 mol% of other dicarboxylic acids selected from the group consisting of aromatic dicarboxylic acids having ˜14 and aliphatic dicarboxylic acids having 4-12 carbon atoms. Method for producing a polyester copolymer copolymerized with glycol. The diol component according to claim 1, wherein the diol component comprises (i) 20 to 35 mol% of neopentyl glycol, (ii) 65 to 80 mol% of ethylene glycol, and (iii) diethylene glycol, triethylene glycol, propanediol, and pentane. Low content oligomer comprising 0-20 mol% of other glycols selected from the group consisting of diol, hexanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol and tetramethylcyclobutanediol Method for producing a polyester resin copolymerized neopentyl glycol having a. The method for producing a polyester resin copolymerized with neopentyl glycol having a low content oligomer according to claim 1, wherein the intrinsic viscosity of the polyester is 0.3 to 2.0 dl / g. The method of claim 6, wherein the (b) crystallization step further comprises a thermal crystallization step of the neopentyl glycol copolymerized polyester resin having a low content oligomer. The method of claim 6, wherein step (c) is neopentyl glycol copolymerized polyester resin having a low oligomer, characterized in that carried out under an inert atmosphere or a reduced pressure of 400 ~ 0.1 Torr at a temperature of 150 to 240 ℃ Manufacturing method. The method of preparing a polyester resin copolymerized with neopentylglycol having a low content oligomer according to claim 6, wherein the dehydration and drying steps are further performed before step (c). A molded article formed by molding the polyester resin according to any one of claims 1 to 5.