KR101709862B1 - Preparation method of low crystalline polyester resin that has improved crystallization characteristic - Google Patents

Abstract

The present invention relates to a method for preparing a low crystalline polyester resin which has reduced crystallinity to prevent turbidity and to improve transparency while allowing solid phase polymerization by virtue of a certain degree of crystallization. The method for preparing a polyester resin according to the present invention comprises the steps of: adding a tertiary alcohol to a slurry mixture comprising a dicarboxylic acid component containing terephthalic acid and a diol component containing cyclohexane dimethanol to form a reaction mixture; subjecting the reaction mixture to esterification; carrying out polycondensation of the esterified reaction mixture; ejecting the polycondensation product to provide molten chips; and crystallizing the molten chips to carry out solid phase polymerization.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a low crystalline polyester resin having improved crystallization characteristics,

The present invention relates to a method for producing a polyester resin, and more particularly, to a method for producing a low crystalline polyester resin with improved crystallization properties.

Polyethylene terephthalate (PET) is a polymer produced through polycondensation reaction through esterification reaction of terephthalic acid (TPA) or dimethyl terephthalate (DMT) and ethylene glycol (EG) as main materials. It has excellent physical properties, processability and economical efficiency. It is environmentally friendly and is used in a wide range of fields such as food and beverage containers and packaging materials, textiles for clothing, film, and others.

In the case of molding with a crystalline resin, the PET is insufficiently cooled or formed into a thick thickness, the quenching efficiency per unit area is lowered due to a rapid crystallization rate, and the whitening phenomenon occurs due to crystallization. In order to prevent such white turbidity, the modified polyester is produced so that the crystallization rate of the resin itself is lowered so that crystallization does not occur under general molding conditions.

In order to satisfy this requirement, DMT or TPA, which is one of the monomers used in PET polymerization, is substituted with Diacid or Diacidester, or EG is substituted with 1,4-cyclohexane dimethanol (CHDM) A PET modified by copolymerization is being developed.

However, since the modified PET is difficult to crystallize due to heat, it can not perform the solid phase polymerization. Therefore, it is difficult to obtain high intrinsic viscosity and the melt polymerization is prolonged because the intrinsic viscosity must be reached only through the melt polymerization. In addition, since the low-molecular reaction by-products generated during the melt polymerization can not be removed to the outside of the resin through the solid phase polymerization, frequent contamination occurs during molding, resulting in marked reduction in molding productivity and difficulty in sufficient drying due to heat for removing moisture.

In order to improve the transparency of the PET resin, it is desirable to lower the crystallinity of the resin itself. However, since a completely amorphous material may cause the above problems, it is necessary to develop a PET resin capable of achieving crystallization to some extent within the range of maintaining the physical properties And the demand for such PET resin molded articles is increasing.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a low crystalline polyester resin having a characteristic of being capable of crystallization to a certain extent and improving the transparency of a resin by preventing crystallization of the resin itself, And a method for producing the same.

According to an aspect of the present invention, there is provided a method for preparing a reaction product, comprising: forming a reaction product by adding a trivalent alcohol to a slurry mixture containing a terephthalic acid-containing dicarboxylic acid component and a cyclohexanedimethanol-containing diol component; Esterifying the reactant; Subjecting the esterification reaction product to a polycondensation reaction; Preparing a molten chip by discharging a reactant formed by the polycondensation reaction; And crystallizing the molten chip to perform solid-state polymerization.

And the cyclohexanedimethanol is contained in an amount of 10 mol% or less in the diol component.

And the trivalent alcohol is added in an amount of 30 wt% or less in ethylene glycol.

And wherein the trihydric alcohol is a straight chain or branched aliphatic trihydric alcohol having 2 to 10 carbon atoms.

And the trivalent alcohol is 1,1,1-tris (hydroxymethyl) propane (1,1,1-tris (hydroxymethyl) propane).

The polyester resin produced by the solid phase polymerization has crystallinity (XC) of 44 to 52% as measured by the following method.

[Method of measuring crystallinity]

The polyester resin was measured for density at a temperature of 23 캜 in a CCl 4 / Xylene-based mill tool pipe, and the crystallinity (XC) was calculated from the following equation (1).

[Equation 1]

(Density of sample, density of crystallized region 1.455 g / cm 3, and density of amorphous region 1.355 g / cm 3)

According to the present invention, a trivalent alcohol is added to a low-crystalline polyester resin containing cyclohexanedimethanol in the diol component to facilitate crystallization so that solid-state polymerization can be carried out to reach the intrinsic viscosity required in the melt polymerization There is an advantage that the melt polymerization time is shortened and the intrinsic viscosity required through solid phase polymerization can be easily achieved.

In addition, since the low-molecular reaction by-products generated during the melt polymerization can be removed to the outside of the resin through the solid-state polymerization, the molding productivity is improved and the moisture can be easily removed through sufficient drying.

In the case of using cyclohexane dimethanol as a monomer for copolymerization, the concentration of cyclohexane dimethanol was conventionally added up to about 30 mol%, but according to the present invention, it is sufficient to add only 10 mol% or less, have.

The polyester resin produced in accordance with the present invention can provide high transparency while having the above characteristics, and can be easily applied to various applications such as fibers, films, adhesives, and industrial fields to provide high quality resin molded articles.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. It is to be understood that various equivalents and modifications may be substituted for those at the time of the present application.

The present inventors have found that when an esterification reaction and a polycondensation reaction are carried out by adding a trivalent alcohol to a slurry mixture containing a dicarboxylic acid component containing terephthalic acid and a diol component comprising cyclohexanedimethanol and other diol compounds, Crystalline polyester resin that can be solid-phase polymerized can be obtained by crystallization to some extent while improving the transparency of the resin by preventing the whitening phenomenon by lowering the crystallization speed of the polyester resin itself, .

Accordingly, the present invention provides a method for producing a slurry mixture, comprising the steps of: adding a trivalent alcohol to a slurry mixture containing a dicarboxylic acid component containing terephthalic acid and a diol component containing cyclohexanedimethanol to form a reaction product; Esterifying the reactant; Subjecting the esterification reaction product to a polycondensation reaction; Preparing a molten chip by discharging a reactant formed by the polycondensation reaction; And crystallizing the molten chip to carry out solid-state polymerization. The polyester resin produced according to the present invention may have a crystallinity (XC) of 44 to 52%, preferably 45 to 51%, more preferably 46 to 50%, as measured by a method described later. , And still more preferably 47 to 49%, so that it is not necessary to reach the intrinsic viscosity required in the melt polymerization by facilitating the crystallization and enabling the solid phase polymerization.

In the present invention, the dicarboxylic acid component is preferably a dicarboxylic acid such as terephthalic acid, an alkyl ester thereof (lower alkyl ester having 1 to 4 carbon atoms such as monomethyl, monoethyl, dimethyl, diethyl or dibutyl ester) and / Of an acid anhydride and may react with the diol component to form a dicarboxylic acid moiety such as a terephthaloyl moiety.

As the dicarboxylic acid component used in the synthesis of the polyester includes terephthalic acid, the heat resistance, the chemical resistance, or the weather resistance (for example, the decrease in molecular weight due to UV or the prevention of sulfur change) of the produced polyester resin Can be improved.

The dicarboxylic acid component may further comprise an aromatic dicarboxylic acid component, an aliphatic dicarboxylic acid component, or a mixture thereof as the other dicarboxylic acid component. Herein, 'other dicarboxylic acid component' means a component other than terephthalic acid among the dicarboxylic acid components.

The aromatic dicarboxylic acid component may be an aromatic dicarboxylic acid having 8 to 20 carbon atoms, preferably 8 to 14 carbon atoms, or a mixture thereof. Examples of the aromatic dicarboxylic acid include naphthalenedicarboxylic acid such as isophthalic acid and 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, 4,4'-stilbenedicarboxylic acid, 2, 5-furandicarboxylic acid, 2,5-thiopendicarboxylic acid, and the like, but the specific examples of the aromatic dicarboxylic acid are not limited thereto.

The aliphatic dicarboxylic acid component may be an aliphatic dicarboxylic acid component having 4 to 20 carbon atoms, preferably 4 to 12 carbon atoms, or a mixture thereof. Examples of the aliphatic dicarboxylic acid include cyclohexanedicarboxylic acid such as 1,4-cyclohexanedicarboxylic acid and 1,3-cyclohexanedicarboxylic acid, phthalic acid, sebacic acid, succinic acid, isodecylsuccinic acid, Linear or branched alicyclic dicarboxylic acid components such as maleic acid, fumaric acid, adipic acid, glutaric acid and azelaic acid. However, the specific examples of the aliphatic dicarboxylic acid are not limited thereto.

The dicarboxylic acid component is used in an amount of 50 to 100 mol%, preferably 70 to 100 mol%, of terephthalic acid; And 0 to 50 mol%, preferably 0 to 30 mol%, of an aromatic dicarboxylic acid or aliphatic dicarboxylic acid.

In the present invention, the diol component includes cyclohexane dimethanol, especially 1,4-cyclohexane dimethanol (CHDM). Generally, when 1,4-cyclohexane dimethanol is used as a monomer for copolymerization, the concentration of 1,4-cyclohexane dimethanol should be increased to about 30 mol%, but according to the present invention, it is sufficient to add only 10 mol% .

As a result of comparing the crystallizabilities of PET resins having similar liquid-phase intrinsic viscosity prepared according to the method of the present invention and the prior art methods to have the same 1,4-cyclohexane dimethanol content, the PET resin Has a crystallinity improved by about 5% as compared with the polyester resin according to the prior art.

In the present invention, the diol component may further include other diol components in addition to the cyclohexanedimethanol. The 'other diol component' means a diol component other than the cyclohexane dimethanol, and may be, for example, an aliphatic diol, an aromatic diol, or a mixture thereof.

The aromatic diol may include an aromatic diol compound having 8 to 40 carbon atoms, preferably 8 to 33 carbon atoms. Examples of such aromatic diol compounds include polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.0) -2,2-bis (4-hydroxyphenyl) Propane, polyoxypropylene- (2.2) -Polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene- (2.3) Bis (4-hydroxyphenyl) propane, polyoxypropylene- (6) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- Propylene, (3,3) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene- (3.0) Ethylene oxide and / or propylene oxide-added bisphenol A derivatives such as 2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene- (6) -2,2-bis (4-hydroxyphenyl) (Polyoxyethylene- (n) -2,2-bis (4-hydroxyphenyl) (N) -2,2-bis (4-hydroxyphenyl) propane or polyoxypropylene- (n) -polyoxyethylene- (n) Phenyl) propane. However, the specific examples of the aromatic diol compound are not limited thereto. Here, n represents the number of polyoxyethylene or polyoxypropylene units.

The aliphatic diol may include an aliphatic diol compound having 2 to 20 carbon atoms, preferably 2 to 12 carbon atoms. Examples of such aliphatic diol compounds include ethylene glycol, diethylene glycol, triethylene glycol, propanediol (such as 1,2-propanediol and 1,3-propanediol), 1,4-butanediol, pentanediol, 1,6-hexanediol), neopentyl glycol (2,2-dimethyl-1,3-propanediol), 1,2-cyclohexanediol, 1,4-cyclohexanediol, Branched or cyclic aliphatic diol components such as methanol, 1,3-cyclohexane dimethanol, 1,4-cyclohexanedimethanol and tetramethyl cyclobutane diol. Specific examples of the aliphatic diol compound are limited thereto It is not.

In the present invention, the trivalent alcohol is added to a slurry mixture of a dicarboxylic acid component and a diol component to lower the crystallization rate of the polyester resin itself. In this case, the trivalent alcohol may be added in a solid or powder form If added to the slurry mixture, the polyester resin finally produced may be yellowed and the flowability of the resin itself may not be uniform due to local crosslinking or gelation. Therefore, in the present invention, trivalent alcohol is mixed and dissolved in ethylene glycol and added to the slurry mixture to be uniformly dispersed, so that stable viscosity increase and uniform flow effect of the reactant can be realized during the polymerization reaction.

When the trihydric alcohol is dissolved in ethylene glycol, it may be used in an amount of not more than 30% by weight. When the trihydric alcohol is dissolved in ethylene glycol in an amount exceeding 30% by weight, the resulting polyester resin may be yellowed as in the case of using the trihydric alcohol in the form of solid or powder, and may be locally crosslinked or gelated The flowability of the resin itself may not be uniform.

Specific examples of the trihydric alcohols include straight chain or branched aliphatic trihydric alcohols having 2 to 10 carbon atoms, preferably 1,1,1-tris (hydroxymethyl) propane (1,1,1- Tris (hydroxymethyl) propane) may be used.

The content of the trivalent alcohol used in the method for producing a polyester resin according to the present invention can be determined in consideration of the melting characteristics and the appearance characteristics of the polyester resin to be finally produced and can prevent the yellowing of the polyester resin, The trihydric alcohol may be added in an amount of 10 to 4,000 ppm, preferably 100 to 3,000 ppm, based on the total weight of the dicarboxylic acid component and the diol component.

As described above, to the slurry mixture containing the dicarboxylic component containing terephthalic acid and the diol component containing cyclohexane dimethanol and other diol compounds, a trihydric alcohol dissolved in ethylene glycol in an amount of 30 wt% or less is added The reaction product is subjected to an esterification reaction and a polycondensation reaction, and the reaction product is crystallized to carry out solid phase polymerization to produce a polyester resin.

The molar ratio of the dicarboxylic acid component to the diol component in the esterification reaction may be from 1: 1.05 to 1: 3.0, and preferably from 1: 1.05 to 1: 1.5.

The esterification reaction may be carried out at a pressure of from 0 to 10.0 kg / cm 2 and at a temperature of from 150 to 330 ° C. At this time, the esterification reaction conditions can be appropriately controlled according to the specific properties of the polyester to be produced, the mole ratio of the dicarboxylic acid component to the glycol, or the process conditions. A preferable example of the esterification reaction conditions is a pressure of 0 to 5.0 kg / cm 2, more preferably 0.1 to 3.0 kg / cm 2, and a temperature condition of 200 to 330 ° C, and more preferably 230 to 280 ° C.

The esterification reaction may be carried out using an esterification catalyst containing at least one compound selected from the group consisting of a zinc compound, a magnesium compound, an antimony compound and a titanium compound.

For example, in the method for producing a polyester resin according to the present invention, an esterification reaction catalyst of 1 to 500 ppm based on the central metal atom may be used as the final resin. Specific examples of the zinc-based compound include zinc acetate, zinc acetate dihydrate, zinc chloride, zinc sulfate, zinc sulfide, zinc carbonate, zinc citrate, zinc gluconate, and mixtures thereof.

The polycondensation reaction may further include adding at least one catalyst compound selected from the group consisting of a titanium compound, a germanium compound, an antimony compound, an aluminum compound, and a tin compound. Accordingly, the polyester resin produced according to the present invention may contain a polycondensation catalyst in an amount of 1 to 500 ppm based on the central metal atom in the whole resin.

Examples of the titanium compound include tetraethyl titanate, acetyl tripropyl titanate, tetrapropyl titanate, tetrabutyl titanate, polybutyl titanate, 2-ethylhexyl titanate, octyleneglycol titanate, lactate titanate , Triethanolamine titanate, acetylacetonate titanate, ethylacetoacetic ester titanate, isostearyl titanate, titanium dioxide, titanium dioxide / silicon dioxide copolymer, and titanium dioxide / zirconium dioxide copolymer

Examples of the germanium compound include germanium dioxide (GeO ₂ ), germanium tetrachloride (GeCl ₄ ), germanium ethyleneglycoxide, germanium acetate, and copolymers thereof , Mixtures thereof, and the like. Preferably, germanium dioxide can be used, and both germanium dioxide can be crystalline or amorphous, and glycol solubility can also be used.

Meanwhile, a phosphorus stabilizer may be used in the synthesis of the polyester resin according to the present invention. Specifically, the polyester stabilizer may further include a step of adding a phosphorus stabilizer to the esterification reaction or the polycondensation reaction.

Specific examples of the phosphorus stabilizer include phosphoric acid, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, triethyl phosphonoacetate, or a mixture of two or more thereof.

Further, in the process of synthesizing the polyester resin according to the present invention, a cobalt compound may be used in order to improve the color during the production of the polyester resin, and the cobalt compound may be used in an amount of 10 to 40 ppm ), Preferably 25 to 35 ppm. When the content of the cobalt compound is less than 10 ppm, the color b value can be increased (a kind of coloring catalyst), and when it exceeds 40 ppm, the production cost can be disadvantageous, and the color L and the color b can be darkened .

Although not limited to these cobalt compounds, it is preferred to use cobalt acetate.

In the present invention, the solid state polymerization may be carried out at a temperature of 195 to 230 ° C and a pressure of 0.2 to 2 torr or under a nitrogen atmosphere after crystallization in an air atmosphere at a reaction temperature of 170 to 185 ° C, for example.

The polyester resin produced by the above process has a crystallinity lower than that of the conventional polyester by 7%, lowering the crystallization speed of the resin itself to prevent the whitening phenomenon, thereby improving the transparency of the resin, .

Hereinafter, the present invention will be described in more detail with reference to specific production examples, examples and comparative examples.

Manufacturing example

A batch type polymerization reactor was used as the melt polymerization reactor used in the production of the polyester resin. The reactor contained one esterification reactor, one polycondensation reactor, and a reactor equipped with a cutting system. The esterification reaction was carried out for 3 to 4 hours, The polycondensation reaction was carried out for 2 to 3 hours and the temperature was raised to 285 DEG C while the pressure was reduced so that the final degree of vacuum was 1.0 torr or less to prepare a polyester resin. In the solid state polymerization reactor, a batch type reactor in which solid phase polymerization was carried out at a reaction temperature of 225 ° C. and a pressure of 0.4 torr or less for 10 hours was used.

Example  One

The diol compound consisting of 95 mol% of ethylene glycol (EG) and 5 mol% of 1,4-cyclohexanedimethanol (CHDM) was mixed at a molar ratio of 1.2 to the dicarboxylic acid compound composed of 100 mol% of terephthalic acid as a main raw material to prepare a slurry Tris (hydroxymethyl) propane (THP) (based on THP content) dissolved in ethylene glycol in an amount of 20% by weight based on the total weight of the polyester resin to be finally produced, and 640 ppm of antimony triacetate Were added to the slurry, the mixture was introduced into an esterification reactor, and the reaction was carried out while slowly raising the temperature to 255 DEG C with stirring at 120 rpm using a stirrer.

When water outflowed from the esterification reaction was discharged out of the system, 200 ppm of triethyl phosphate (TEP) and 160 ppm of cobalt acetate as a coloring agent were added as a stabilizer. After stirring for 10 minutes, the contents were transferred to a polycondensation reactor.

Thereafter, the internal temperature was raised from 250 ° C to 280 ° C, and the pressure was gradually reduced from atmospheric pressure to 0.1 torr over 1 hour, and subjected to polycondensation reaction under high vacuum until the desired intrinsic viscosity was reached.

The molten chips thus cut are transferred to a solid phase polymerization reactor through a crystallizer having an air atmosphere at a temperature of 170 to 185 ° C to carry out a solid phase polymerization reaction at a temperature of 195 to 230 ° C and a pressure of 0.2 to 2 torr or under a nitrogen atmosphere, To prepare an ester resin.

Comparative Example 1

Cyclohexane dimethanol was introduced into an esterification reactor and esterification reaction was carried out in the same manner as in Example 1. After completion of the esterification reaction, 1 g of ethylene glycol (EG) was added to the reaction product , And 1,1-tris (hydroxymethyl) propane was not added to the polyester resin, a polyester resin was prepared in the same manner as in Example 1.

Comparative Example 2

Except that a solution obtained by mixing 1,1,1-tris (hydroxymethyl) propane with ethylene glycol (EG) was not added to the reaction product after completion of the esterification reaction in Example 1 To prepare a polyester resin.

Experimental Example

The intrinsic viscosity, crystallinity and crystallization temperature of the polyester resin prepared according to the Examples and Comparative Examples were measured by the following methods, and the results of physical properties and evaluation results of the solid phase polymerization ease are shown in Table 1 below.

[How to measure]

(1) Intrinsic Viscosity

The polyester resin obtained in the above Examples and Comparative Examples was dissolved in a solution containing 60 parts by weight of phenol and 40 parts by weight of 1,1,2,2-tetrachloroethane at a ratio of 0.5 part by weight, and then the mixture was subjected to a Cannon-Ubbelohde microviscometer The intrinsic viscosity (IV) was measured at 30 ° C.

(2) Crystallinity

Crystallinity (XC) was calculated from the following formula (1) after measuring the densities of the polyester resins obtained in the above Examples and Comparative Examples in a CCl 4 / Xylene type mill tool pipe at 23 ° C.

[Equation 1]

(Density of sample, density of crystallized region 1.455 g / cm 3, and density of amorphous region 1.355 g / cm 3)

(3) Crystallization temperature

The crystallization temperatures of the polyester resins obtained in the above Examples and Comparative Examples were measured using an injection latent heat calorimeter (DSC).

Referring to Table 1, the polyester resin synthesized according to Comparative Example 1 had crystallinity of about 55% and crystallization was very easy, but there was a problem of transparency lowering due to opacity, The polyester resin was obtained by copolymerizing 1,4-cyclohexane dimethanol (CHDM) and reducing the crystallization rate to about 48% by adding 1,1,1-tris (hydroxymethyl) propane (THP) It can be confirmed that crystallization is possible while improving transparency, thereby facilitating solid phase polymerization.

In addition, the polyester resin to which 1,1,1-tris (hydroxymethyl) propane (THP) was not added according to Comparative Example 2 had a poor solid state polymerization state due to a low crystallinity of 43%. On the contrary, the polyester resin synthesized according to Example 1 exhibited a crystallization increase of about 48% by the addition of 1,1,1-tris (hydroxymethyl) propane (THP) Able to know.

The preferred embodiments of the present invention have been described in detail above. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning, range, and equivalence of the claims are included in the scope of the present invention Should be interpreted.

Claims (6)

Adding a trivalent alcohol to a slurry mixture containing a terephthalic acid-containing dicarboxylic acid component and a cyclohexane dimethanol-containing diol component to form a reaction product;
Esterifying the reactant;
Subjecting the esterification reaction product to a polycondensation reaction;
Preparing a molten chip by discharging a reactant formed by the polycondensation reaction; And
Crystallizing the molten chip to perform solid phase polymerization;
, ≪ / RTI &
The cyclohexane dimethanol is contained in an amount of 10 mol% or less in the diol component,
Wherein the polyester resin produced by the solid phase polymerization has a crystallinity (XC) of 44 to 52% as measured by the following method.
[Method of measuring crystallinity]
The polyester resin was measured for density at a temperature of 23 캜 in a CCl 4 / Xylene-based mill tool pipe, and the crystallinity (XC) was calculated from the following equation (1).
[Equation 1]

(Density of sample, density of crystallized region 1.455 g / cm 3, and density of amorphous region 1.355 g / cm 3) delete The method according to claim 1,
Wherein the trivalent alcohol is added in an amount of not more than 30 wt% dissolved in ethylene glycol. The method according to claim 1,
Wherein the trihydric alcohol is a straight chain or branched aliphatic trihydric alcohol having 2 to 10 carbon atoms. 5. The method of claim 4,
Wherein the trivalent alcohol is 1,1,1-tris (hydroxymethyl) propane (1,1,1-tris (hydroxymethyl) propane). delete