阅读说明：本技术 聚酯树脂以及聚酯树脂的制备方法 (Polyester resin and method for producing polyester resin ) 是由 金志玹 金钟亮 安哲熙 于 2019-03-05 设计创作，主要内容包括：提供了聚酯树脂及其制备方法,所述聚酯树脂具有高的异山梨醇留存率,从而呈现出优异的耐热性、优异的机械性质诸如抗拉强度、杨氏模量等以及优异的外观性质和透明度。(Provided are a polyester resin having a high isosorbide retention rate, thereby exhibiting excellent heat resistance, excellent mechanical properties such as tensile strength, Young's modulus, etc., and excellent appearance properties and transparency, and a method for preparing the same.)

1. A polyester resin, comprising:

a portion of a dicarboxylic acid component comprising terephthalic acid; and

a portion of a glycol component comprising isosorbide and 1, 2-propanediol,

wherein the isosorbide-derived moiety is 5 mol% or more and the 1, 2-propanediol-derived moiety is 10 mol% or more, out of 100 mol% of the fraction of the diol component.

2. The polyester resin of claim 1, wherein the portion of the glycol component comprises 5 to 70 mole% of an isosorbide-derived portion and 30 to 95 mole% of a 1, 2-propanediol-derived portion.

3. The polyester resin according to claim 1, wherein a glass transition temperature (Tg) is 80 ℃ or more.

4. The polyester resin of claim 1, wherein the glycol component comprises one or more glycol compounds selected from the group consisting of C8-C40 aromatic glycols and C2-C20 aliphatic glycols, in addition to isosorbide and 1, 2-propanediol.

5. The polyester resin according to claim 1, wherein the glycol component comprises 1, 4-cyclohexanedimethanol in addition to isosorbide and 1, 2-propanediol, and the portion of the glycol component comprises 5 to 45 mole% of an isosorbide-derived portion, 10 to 50 mole% of a 1, 2-propanediol-derived portion, and the balance of a 1, 4-cyclohexanedimethanol-derived portion.

6. The polyester resin of claim 1, wherein the dicarboxylic acid component comprises one or more acid components selected from the group consisting of C8-C20 aromatic dicarboxylic acid component and C4-C20 aliphatic dicarboxylic acid component in addition to terephthalic acid.

7. The polyester resin of claim 1, further comprising moieties of a C6-C20 polyfunctional carboxylic acid component.

8. A method of preparing a polyester resin wherein the isosorbide retention in the polyester is 40% or greater, comprising the steps of:

at 0.2kg/cm²To 3.0kg/cm²And at a temperature of from 200 ℃ to 300 ℃, an esterification reaction or transesterification reaction between a dicarboxylic acid component comprising terephthalic acid and a diol component comprising isosorbide and 1, 2-propanediol; and

the polycondensation reaction of the reaction product is carried out under reduced pressure of 400mmHg to 0.1mmHg and at a temperature of 240 ℃ to 300 ℃.

9. The method of claim 8, wherein the glycol component comprises 5 to 70 mol% isosorbide and 30 to 95 mol% 1, 2-propanediol, relative to 100 mol% total of the glycol component.

10. The process of claim 8 wherein the glycol component further comprises 1, 4-cyclohexanedimethanol.

11. The method of claim 10, wherein the glycol component comprises 5 to 50 mole% isosorbide, 10 to 75 mole% 1, 2-propanediol, and the balance 1, 4-cyclohexanedimethanol, relative to the total 100 mole% of the glycol component.

12. The process of claim 8 wherein the molar ratio of the dicarboxylic acid component to the diol component is from 1:1 to 1: 3.

13. The process of claim 8 wherein a C6-C20 polyfunctional carboxylic acid component is additionally included in the step of esterification or transesterification.

Technical Field

Cross Reference to Related Applications

The present application is based on and claims priority from korean patent application nos. 10-2018-0028779 and 10-2019-0002465, which are filed on 12.3.2018 and 8.1.2019, respectively, the disclosures of which are hereby incorporated by reference in their entireties.

The present invention relates to a polyester resin and a method for preparing the same. More particularly, the present invention relates to a polyester resin exhibiting excellent physical properties such as high heat resistance, impact resistance, etc., and having excellent appearance properties, high transparency, and molding characteristics, and a method for preparing the same.

Background

In general, polyester resins prepared from aromatic and/or aliphatic dicarboxylic acids and diols having an optimal structure have excellent physical and chemical properties, have solubility and flexibility in general solvents, have good adhesion to a wide range of materials and good coating workability (coating workability), etc., and thus are used in various applications such as for fibers, films, adhesives, etc.

In order to improve physical properties of such polyester resins, polyester resins copolymerized with two or more diol components or dicarboxylic acid components have been widely used commercially. In particular, there is a known method using isosorbide (1,4:3,6-dianhydroglucitol) which is an environmentally friendly diol compound derived from starch as one of the monomers. The polyester resin including isosorbide exhibits a high glass transition temperature, and thus can be variously applied to articles required to have heat resistance.

Meanwhile, in the preparation of the polyester resin, the proportion of the raw materials present in the main chain of the final polyester resin varies depending on the reactivity of the raw materials during the esterification reaction or the transesterification reaction and the degree of vaporization of the raw materials during the polycondensation reaction. With respect to the diol component represented by an alkylene diol, a secondary alcohol or a tertiary alcohol is less reactive than a primary alcohol, and a tertiary alcohol is less reactive than a secondary alcohol. For this reason, when a secondary alcohol or a tertiary alcohol is included as a raw material, there is a problem in that: their retention rate in the main chain of the polyester resin is low, the reaction time is greatly increased, or the reaction yield is significantly reduced.

The secondary alcohol isosorbide also exhibits a low retention rate in the main chain of the polyester due to its low reactivity, and therefore has a problem that: it is difficult to sufficiently achieve desired physical properties such as heat resistance, impact resistance, and the like. Therefore, there is a need for a new composition of polyester resin and a method for preparing the same that can overcome the problem of low retention of isosorbide.

BRIEF SUMMARY OF THE PRESENT DISCLOSURE

Technical problem

In order to solve the above problems, an object of the present invention is to provide a polyester resin having an improved isosorbide retention rate, thereby exhibiting excellent physical properties such as heat resistance, chemical resistance, impact resistance, etc., and having excellent appearance properties, high transparency and molding characteristics, and a method for preparing the same.

Technical scheme

Provided is a polyester resin including:

a portion of a dicarboxylic acid component comprising terephthalic acid; and

a portion of a glycol component comprising isosorbide and 1, 2-propanediol,

wherein the isosorbide-derived moiety is 5 mol% or more and the 1, 2-propanediol-derived moiety is 10 mol% or more, among 100 mol% of the fraction of the diol component.

Preferably, the portion of the glycol component can include 5 to 70 mole% of the isosorbide-derived portion and 30 to 95 mole% of the 1, 2-propanediol-derived portion.

Preferably, the polyester resin may have a glass transition temperature (Tg) of 80 ℃ or more.

According to an exemplary embodiment of the present invention, the glycol component may include one or more glycol compounds selected from the group consisting of C8-C40 aromatic glycols and C2-C20 aliphatic glycols, in addition to isosorbide and 1, 2-propanediol.

In an exemplary embodiment, the glycol component can include 1, 4-cyclohexanedimethanol in addition to isosorbide and 1, 2-propanediol. In this regard, the portion of the glycol component can include 5 to 45 mole% of the isosorbide-derived portion, 10 to 50 mole% of the 1, 2-propanediol-derived portion, and the balance 1, 4-cyclohexanedimethanol-derived portion.

In addition to terephthalic acid, the dicarboxylic acid component may also include one or more acid components selected from the group consisting of C8-C20 aromatic dicarboxylic acid components and C4-C20 aliphatic dicarboxylic acid components.

In addition, the polyester resins of the present invention may include moieties of C6-C20 polyfunctional carboxylic acid components.

Further, there is provided a method for producing a polyester resin, wherein the retention rate of isosorbide in a polyester is 40% or more, comprising the steps of:

at 0.2kg/cm²To 3.0kg/cm²And at a temperature of from 200 ℃ to 300 ℃, an esterification reaction or transesterification reaction between a dicarboxylic acid component comprising terephthalic acid and a diol component comprising isosorbide and 1, 2-propanediol; and

the polycondensation reaction of the reaction product is carried out under reduced pressure of 400mmHg to 0.1mmHg and at a temperature of 240 ℃ to 300 ℃.

In the method of preparing a polyester resin according to an exemplary embodiment of the present invention, the glycol component may include 5 to 70 mol% of isosorbide and 30 to 95 mol% of 1, 2-propanediol with respect to the total 100 mol% of the glycol component.

Alternatively, the diol component may also include 1, 4-cyclohexanedimethanol. In this regard, the glycol component can include 5 to 50 mole% isosorbide, 10 to 75 mole% 1, 2-propanediol, and the balance 1, 4-cyclohexanedimethanol, relative to 100 mole% total of the glycol component.

In the method of preparing a polyester resin according to an exemplary embodiment of the present invention, the molar ratio of the dicarboxylic acid component and the diol component may be 1:1 to 1: 3.

Further, according to an exemplary embodiment of the present invention, the C6-C20 polyfunctional carboxylic acid component may also be included in the step of esterification reaction or transesterification reaction.

ADVANTAGEOUS EFFECTS OF INVENTION

The polyester resin of the present invention has a high isosorbide retention rate, thereby exhibiting excellent heat resistance and excellent mechanical properties such as tensile strength, young's modulus, etc., as well as excellent appearance properties and transparency.

Best mode for carrying out the invention

Hereinafter, the present invention will be described in detail.

Polyester resin

Provided is a polyester resin including:

a portion of a dicarboxylic acid component comprising terephthalic acid; and

a portion of a glycol component comprising isosorbide and 1, 2-propanediol,

wherein the isosorbide-derived moiety is 5 mol% or more and the 1, 2-propanediol-derived moiety is 10 mol% or more, among 100 mol% of the fraction of the diol component.

Generally, the polyester resin mainly includes ethylene glycol as a glycol component, and includes a glycol improving physical properties in addition to ethylene glycol. When isosorbide (1,4:3,6-dianhydroglucitol) is added to a polyester resin, the polyester resin exhibits improved heat resistance and improved physical properties such as chemical resistance, chemical resistanceAnd the like. For this reason, isosorbide is used as the diol component together with ethylene glycol. However, since isosorbide is a secondary alcohol, the process is not limited to the use of sorbitolThis is very low in reactivity with isosorbide compared to ethylene glycol, which is a primary alcohol. Therefore, it is difficult to obtain a resin having a high molecular weight due to the decreased polymerization degree, and the retention rate of isosorbide in the polyester resin is decreased. Therefore, there has been a problem that: the desired level of heat resistance may not be sufficiently obtained.

In order to solve the above problems, the present inventors have conducted various studies, and as a result, they have found that when 1, 2-propanediol is used instead of the commonly used ethylene glycol, the reactivity of isosorbide is increased, and thus a resin having a high molecular weight can be obtained, and the retention rate of isosorbide in the main chain of the produced polyester resin can be increased. Therefore, the polyester resin of the present invention exhibits improved heat resistance and chemical resistance due to increased isosorbide retention. In addition, the polyester resin of the present invention exhibits mechanical properties such as tensile strength, young's modulus, etc., which are equivalent to or higher than those of polyester resins including ethylene glycol and having similar isosorbide content. Therefore, the polyester resin of the present invention can be preferably applied to food containers and packaging materials, packaging materials and materials for medical use, building materials, vehicle interior materials, electronic product materials, and the like by injection molding and extrusion molding.

As used herein, the retention ratio refers to the content of the monomer included in the final polyester after the polymerization process with respect to the input amount of each raw material (monomer). For example, the retention of isosorbide can be calculated by the following equation 1.

[ equation 1]

Retention (%) of isosorbide (%) (mol% of isosorbide-derived moiety in 100 mol% of the diol component part of the polyester resin)/(mole number of isosorbide injected during preparation of polyester resin) × 100

As used herein, the term 'moiety' refers to a certain segment or unit that is included in the product of a chemical reaction and that is derived from a particular compound when the particular compound participates in the chemical reaction. For example, a 'portion' of a dicarboxylic acid component or a 'portion' of a diol component refers to a segment derived from a dicarboxylic acid component or a segment derived from a diol component in a polyester formed by an esterification reaction or a polycondensation reaction, respectively.

The dicarboxylic acid component is intended to include dicarboxylic acids such as terephthalic acid and the like, alkyl esters thereof (including C1-C4 lower alkyl esters such as monomethyl, monoethyl, dimethyl, diethyl, dibutyl esters, and the like), and/or anhydrides thereof. The dicarboxylic acid may be reacted with the diol component to form dicarboxylic acid moieties such as terephthaloyl moieties and the like.

When the dicarboxylic acid component used for the synthesis of the polyester includes terephthalic acid, physical properties of the prepared polyester resin such as heat resistance, chemical resistance, weatherability (for example, prevention of molecular weight reduction or yellowing caused by UV), and the like may be improved.

The dicarboxylic acid component may also include an aromatic dicarboxylic acid component, an aliphatic dicarboxylic acid component, or a mixture thereof as the other dicarboxylic acid component. In this regard, the term 'other dicarboxylic acid component' means a dicarboxylic acid component other than terephthalic acid among the dicarboxylic acid components.

The aromatic dicarboxylic acid component may be a C8-C20 aromatic dicarboxylic acid, preferably a C8-C14 aromatic dicarboxylic acid, mixtures thereof, and the like. Examples of the aromatic dicarboxylic acid include phthalic acid, isophthalic acid, naphthalene dicarboxylic acid such as 2, 6-naphthalene dicarboxylic acid and the like, biphenyl dicarboxylic acid, 4' -diphenylethylene dicarboxylic acid, 2, 5-furan dicarboxylic acid, 2, 5-thiophene dicarboxylic acid and the like, but specific examples of the aromatic dicarboxylic acid are not limited thereto.

The aliphatic dicarboxylic acid component can be a C4-C20 aliphatic dicarboxylic acid component, preferably a C4-C12 aliphatic dicarboxylic acid component, mixtures thereof, and the like. Examples of the aliphatic dicarboxylic acid include cyclohexanedicarboxylic acids such as 1, 4-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, and the like, and linear, branched, or cyclic aliphatic dicarboxylic acid components such as sebacic acid, succinic acid, isodecylsuccinic acid, maleic acid, fumaric acid, adipic acid, glutaric acid, azelaic acid, and the like, but specific examples of the aliphatic dicarboxylic acid are not limited thereto. Such an aliphatic dicarboxylic acid can lower the glass transition temperature of the resin as compared with an aromatic dicarboxylic acid, and therefore the aliphatic dicarboxylic acid is preferably used in as small an amount as possible, for example, the aliphatic dicarboxylic acid-derived portion is 30 mol% or less of the dicarboxylic acid-derived portion.

The portion of the dicarboxylic acid component may comprise from 50 to 100 mole%, preferably from 70 to 100 mole%, of the terephthalic acid-derived portion; and 0 to 50 mol%, preferably 0 to 30 mol%, of one or more dicarboxylic acid-derived moieties selected from the group consisting of aromatic dicarboxylic acids and aliphatic dicarboxylic acids. If the content of the terephthalic acid-derived moiety in the dicarboxylic acid component moiety is too small, physical properties of the polyester resin such as heat resistance, chemical resistance or weatherability may be deteriorated.

Further, in the present invention, a polyfunctional carboxylic acid may be used in addition to the dicarboxylic acid. A multifunctional carboxylic acid refers to a carboxylic acid having three or more carboxyl groups. The polyfunctional carboxylic acid is a C6-C20 aromatic or aliphatic polyfunctional carboxylic acid component, preferably a C6-C9 aromatic or aliphatic polyfunctional carboxylic acid component, and includes trimellitic acid (trimelitic acid), trimellitic anhydride, hemimellitic acid, trimellitic anhydride, trimesic acid, tricarballylic acid, and the like, but is not limited thereto.

The polyfunctional carboxylic acid has an advantage of improving processability during extrusion molding by increasing melt viscosity of the resin through crosslinking. However, when the polyfunctional carboxylic acid is used in excess, the melt viscosity of the resin becomes too high to deteriorate the processability, and the resin becomes brittle, which may deteriorate physical properties such as impact strength and the like. Therefore, a polyfunctional carboxylic acid is optionally used according to necessity, and the portion of the polyfunctional carboxylic acid component in the range of 0 to 5 mol% is preferably used with respect to 100 mol% of the portion of the dicarboxylic acid component.

The diol component included in the polyester resin of the present invention may include isosorbide and 1, 2-propanediol, and may also include other diol compounds.

Isosorbide is included as one of the diol components in order to improve the physical properties of the resin such as heat resistance, chemical resistance and chemical resistance. According to an exemplary embodiment of the invention, the isosorbide-derived fraction is comprised in an amount of 5 mol% or more, in particular in the range of 5 mol% to 70 mol% and more preferably in the range of 10 mol% to 60 mol% in 100 mol% of the fraction of the diol component. If the content of the isosorbide-derived moiety is less than 5 mol%, it is difficult to obtain the heat resistance of the polyester resin. If the content of the isosorbide-derived moiety is more than 70 mol%, the appearance properties of the polyester resin may be deteriorated or yellowing may occur. Therefore, it is preferable that the content satisfies the above range.

1, 2-propanediol is one of the diol components, which is included as a substitute for ethylene glycol, and is included to increase the flowability and mechanical strength of the polyester resin, and to increase the retention rate of isosorbide. Generally, ethylene glycol is mainly used as the glycol component of the polyester resin. However, when 1, 2-propanediol is used instead of ethylene glycol, there is an effect of improving the retention rate of isosorbide in the main chain, and therefore, the heat resistance and durability of the produced polyester resin can be improved. In addition, the polyester resin including 1, 2-propanediol exhibits heat resistance and mechanical properties that are equivalent to or higher than those of the polyester resin including ethylene glycol and having the same isosorbide content.

In order to ensure the above effects, the 1, 2-propanediol-derived moiety is preferably included in an amount of 10 mol% or more, 20 mol% or more, or 30 mol% or more, and 95 mol% or less, or 90 mol% or less, among 100 mol% of the portion of the diol component.

In particular, the polyester resin of the present invention may include 5 to 70 mol% of an isosorbide-derived moiety and 30 to 95 mol% of a 1, 2-propanediol-derived moiety in 100 mol% of the fraction of the diol component, or may include 10 to 60 mol% of an isosorbide-derived moiety and 40 to 90 mol% of a 1, 2-propanediol-derived moiety.

Meanwhile, in the present invention, other diol compounds that may be included in addition to isosorbide and 1, 2-propanediol are not particularly limited as long as they are generally used for preparing polyesters. For example, the other diol compound may be an aliphatic diol, an aromatic diol, or a mixture thereof.

The aromatic diol may include a C8-C40 aromatic diol compound, preferably a C8-C33 aromatic diol compound. Examples of the aromatic diol compound may include ethylene oxide-added bisphenol a derivatives such as polyoxyethylene- (2.0) -2, 2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.2) -polyoxyethylene- (2.0) -2, 2-bis (4-hydroxyphenyl) propane, polyoxyethylene- (2.3) -2, 2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (6) -2, 2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.3) -2, 2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.4) -2, 2-bis (4-hydroxyphenyl) propane, polyoxyethylene- (2.4) -2, 2-bis (4-hydroxyphenyl) propane, ethylene oxide-added bisphenol a derivatives, Polyoxypropylene- (3.3) -2, 2-bis (4-hydroxyphenyl) propane, polyoxyethylene- (3.0) -2, 2-bis (4-hydroxyphenyl) propane, polyoxyethylene- (6) -2, 2-bis (4-hydroxyphenyl) propane, and the like, and/or propylene oxide-added bisphenol A derivatives (polyoxyethylene- (n) -2, 2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (n) -polyoxyethylene- (n) -2, 2-bis (4-hydroxyphenyl) propane, etc., here, n means the number of polyoxyethylene units or polyoxypropylene units.

The aliphatic diol may comprise a C2-C20 aliphatic diol compound, preferably a C2-C12 aliphatic diol compound. Examples of the aliphatic diol compound may include linear, branched or cyclic aliphatic diol components such as ethylene glycol, diethylene glycol, triethylene glycol, 1, 3-propanediol, 1, 4-butanediol, 2, 3-butanediol, 1, 3-butanediol, pentanediol (1, 5-pentanediol, etc.), hexanediol (e.g., 1, 6-hexanediol, etc.), neopentyl glycol (2, 2-dimethyl-1, 3-propanediol), 1, 2-cyclohexanediol, 1, 4-cyclohexanediol, 1, 2-cyclohexanedimethanol, 1, 3-cyclohexanedimethanol, 1, 4-cyclohexanedimethanol and tetramethylcyclobutanediol, but specific examples of the aliphatic diol compound are not limited thereto.

When the other glycol compound described above is additionally included as the glycol component, the portion derived from the other glycol compound is preferably included in an amount of less than 70 mol%, or less than 60 mol%, or less than 50 mol% in the portion of 100 mol% of the glycol component, and the lower limit of the content may be, but is not limited to, particularly 0 mol% or more, 5 mol% or more, or 10 mol% or more. If the content of the other diol compound-derived portion in the portion of the diol component exceeds 70 mol%, the content of the isosorbide-derived portion and 1, 2-propanediol-derived portion is relatively reduced, and thus it is difficult to sufficiently secure the effects of heat resistance, chemical resistance, tensile strength, and the like. In particular, diethylene glycol, triethylene glycol, 1, 3-propanediol, 1, 4-butanediol, 2, 3-butanediol, 1, 3-butanediol, pentanediol (1, 5-pentanediol, etc.), hexanediol (1, 6-hexanediol, etc.), and neopentyl glycol (2, 2-dimethyl-1, 3-propanediol) can lower the glass transition temperature of the resin compared to other aliphatic diols, and therefore, the aliphatic diol-derived portion is preferably used in an amount as small as possible, for example, in an amount of 30 mol% or less or in an amount in the range of 0 mol% to 10 mol% in 100 mol% of the portion of the diol component.

Meanwhile, according to an exemplary embodiment of the present invention, 1, 4-cyclohexanedimethanol may be used as other diol compounds in order to improve impact resistance of the polyester resin. As described, the polyester resin further comprising 1, 4-cyclohexanedimethanol may particularly comprise 5 to 45 mol% of an isosorbide-derived moiety, 10 to 50 mol% of a 1, 2-propanediol-derived moiety and the balance of a 1, 4-cyclohexanedimethanol-derived moiety, or 5 to 40 mol% of an isosorbide-derived moiety, 20 to 45 mol% of a 1, 2-propanediol-derived moiety and the balance of a 1, 4-cyclohexanedimethanol-derived moiety, in a fraction of 100 mol% of the diol component. When the content of the portion of the diol component satisfies the above range, it is preferable in terms of ensuring heat resistance, chemical resistance, impact resistance, and the like.

The above-described polyester resin of the present invention may include isosorbide as a diol component to exhibit excellent heat resistance and strength. In particular, the polyester resin of the present invention may have a glass transition temperature (Tg) of 80 ℃ or more, 90 ℃ or more, 95 ℃ or more, or 100 ℃ or more, and a young's modulus of 1350MPa or more, 1400MPa or more, or 1450MPa or more. The method of measuring the glass transition temperature and young's modulus may be specifically illustrated in exemplary embodiments described below.

Further, the polyester resin of the present invention has an Intrinsic Viscosity (IV) of 0.45 or more, 0.50 or more, or 0.52 or more, and exhibits a high molecular weight even if isosorbide is included.

As described, since the polyester resin of the present invention exhibits a high molecular weight and excellent heat resistance and strength properties, it can be suitably applied to food containers and packaging materials required to have heat resistance and rigidity, packaging materials and equipment for medical use, vehicle materials and electronic product materials, building materials, and the like.

Process for producing polyester resin

Meanwhile, a method of preparing the above-described polyester resin of the present invention is provided. In particular, there is provided a process for preparing a polyester resin, the process comprising the steps of:

at 0.2kg/cm²To 3.0kg/cm²And at a temperature of from 200 ℃ to 300 ℃, an esterification reaction or transesterification reaction between a dicarboxylic acid component comprising terephthalic acid and a diol component comprising isosorbide and 1, 2-propanediol; and

the polycondensation reaction of the reaction product is carried out under reduced pressure of 400mmHg to 0.1mmHg and at a temperature of 240 ℃ to 300 ℃.

According to the production method of the present invention in which 1, 2-propanediol is used as a diol component instead of ethylene glycol which is commonly used, it is possible to solve the problems of decreased degree of polymerization caused by low reactivity of isosorbide and decreased isosorbide retention in the main chain of polyester, and therefore, it is possible to produce a polyester resin having excellent heat resistance, mechanical properties, appearance properties and moldability (moldability).

In the method of preparing the polyester resin of the present invention, the dicarboxylic acid component may include 1 to 100 mol% or 30 to 100 mol% of terephthalic acid, alkyl esters thereof and/or anhydrides thereof, and the balance of the above-described other aromatic and/or aliphatic dicarboxylic acid components, with respect to the total 100 mol% of the dicarboxylic acid component.

When only isosorbide and 1, 2-propanediol are used as the diol component, 5 to 70 mol% of isosorbide and 30 to 95 mol% of 1, 2-propanediol may be included with respect to 100 mol% of the total diol component.

Meanwhile, when the other glycol compounds described above are included as the glycol component, the other glycol compounds may preferably be included in an amount of less than 80 mol%, less than 70 mol%, or less than 60 mol% with respect to the total 100 mol% of the glycol component, in addition to isosorbide and 1, 2-propanediol.

More particularly, when 1, 4-cyclohexanedimethanol is additionally included as the other diol compound, 5 to 50 mol% of isosorbide, 10 to 75 mol% of 1, 2-propanediol and the balance of 1, 4-cyclohexanedimethanol may be preferably included with respect to the total 100 mol% of the diol component.

After the above input amounts of the dicarboxylic acid component and the diol component are satisfied, a polyester resin having a portion of the dicarboxylic acid component and a portion of the diol component within an appropriate content range may be prepared.

Further, the molar ratio of the dicarboxylic acid component and the diol component is preferably in the range of 1:1 to 1:3 or 1:1.05 to 1: 2.05. If the molar ratio of the dicarboxylic acid component and the diol component is less than 1:1, unreacted acid component may remain during polymerization, resulting in poor transparency of the resin. If the molar ratio is more than 1:3, the polymerization rate becomes too slow, and therefore, the productivity of the resin may be deteriorated. Therefore, it is preferable that the molar ratio satisfies the above range.

The C6-C20 polyfunctional carboxylic acid described above may be included in addition to the dicarboxylic acid component and the diol component during the esterification reaction or the transesterification reaction. In this case, the processability of the polyester resin as prepared above can be improved. However, when used in excess, processability may be deteriorated, and physical properties such as impact strength may be deteriorated. Therefore, it is preferable to use the polyfunctional dicarboxylic acid in the range of 0 to 5 mol% with respect to 100 mol% of the dicarboxylic acid component.

The esterification reaction or the transesterification reaction (hereinafter, referred to as esterification reaction) may be carried out in a batch or continuous manner. The raw materials may be injected separately, but preferably a slurry formed by mixing the dicarboxylic acid component and the diol component is injected. At this time, water may be additionally added to increase the solubility of a diol component such as isosorbide or the like, which is in the form of a solid at room temperature, or a slurry may be prepared at 60 ℃ or higher to melt the solid.

The esterification reaction may be at a temperature of 200 ℃ to 300 ℃, preferably 220 ℃ to 280 ℃ and more preferably 235 ℃ to 265 ℃, and at 0.1kg/cm²To 3.0kg/cm²And preferably 0.2kg/cm²To 3.0kg/cm²Is carried out under pressure. At this time, it is preferable that water or alcohol generated as a byproduct during the esterification reaction is continuously discharged from the reactor to increase the reaction rate.

The esterification time (average retention time) may be generally 100min to 10h and preferably 2h to 500min, and may vary depending on the reaction temperature and pressure and the molar ratio of the dicarboxylic acid component and the diol component to be used.

The esterification reaction may be carried out without a catalyst, but may be carried out by adding an appropriate catalyst in order to shorten the reaction time. Suitable catalysts may include titanium-based catalysts, aluminum-based catalysts, tin-based catalysts, germanium-based catalysts, antimony-based catalysts, and the like, and these catalysts may serve as catalysts for the subsequent polycondensation reaction.

As useful titanium-based catalysts, tetraethyl titanate, acetyltripropyl titanate, tetrapropyl titanate, tetrabutyl titanate, polybutyltitanate (polybutyltitanate), 2-ethylhexyl titanate, octylglycol titanate, lactic acid titanate (lactylate titanate), triethanolamine titanate, acetylacetonato titanate (acetylacetonate), ethylacetoacetate titanate (ethylacetoacetate titanate), isostearyl titanate (isostearyl titanate), titanium dioxide/silica copolymer or titanium dioxide/zirconium dioxide copolymer can be exemplified. As the germanium-based catalyst, germanium dioxide or a copolymer thereof can be exemplified. Examples of the tin-based catalyst include tetrabutyldibutyldibutoxytin oxide (tetrabutyldutoxytin oxide), dibutyltin oxide, and dibutyltin dilaurate. These catalysts may be used alone or in combination.

The catalyst may be preferably used in the range of 10ppm to 500ppm or 100ppm to 300ppm with respect to the total weight of the dicarboxylic acid component and the diol component as raw materials, in accordance with the central metal of the catalyst. If the content of the catalyst is less than 10ppm, the amount of the catalyst may be insufficient and thus the reaction rate may become slow, and if the content exceeds 500ppm, a side reaction may occur or the catalyst may remain in the polyester resin to be produced. Therefore, it is preferable that the content of the catalyst satisfies the above range.

In the esterification reaction, a phosphorus-based stabilizer such as phosphoric acid, trimethyl phosphate, triethyl phosphate, or the like may be additionally added. The stabilizer based on phosphorus may be added in an amount of 30ppm to 500ppm or 50ppm to 300ppm in terms of phosphorus, relative to the total weight of the raw materials. If the amount of the stabilizer added is less than 30ppm, the stabilizing effect is poor, and thus the color of the polyester resin may turn yellow. If the amount added exceeds 500ppm, a polymer having a desired high polymerization degree cannot be obtained.

After the esterification reaction is completed, the polycondensation reaction is performed. The polycondensation reaction is carried out at a temperature of 230 ℃ to 300 ℃, preferably 240 ℃ to 290 ℃ and more preferably 250 ℃ to 280 ℃, and under reduced pressure of 400mmHg to 0.1 mmHg. The reduced pressure condition of 400mmHg to 0.1mmHg is to remove glycol and oligomer as a by-product of the polycondensation reaction. The polycondensation reaction is carried out for the required time until the desired intrinsic viscosity is reached, for example for an average retention time of 1h to 10 h.

When the polyester resin is prepared according to the preparation method of the present invention, the retention rate of isosorbide is as high as 40% or more, or 45% or more, or 50% or more. Therefore, the polyester resin prepared by the method may exhibit excellent heat resistance, chemical resistance and mechanical properties. The retention ratio refers to the content of the monomer included in the final polyester after the polymerization process with respect to the input amount of the raw material (monomer).

Further, according to the preparation method of the present invention, the reactivity of isosorbide may be improved to increase the degree of polymerization, and the resulting polyester resin may exhibit a high Intrinsic Viscosity (IV) of 0.45 or more, 0.50 or more, or 0.52 or more.

Hereinafter, the action and effect of the present invention will be described in more detail with reference to specific examples thereof. However, these examples are for illustrative purposes only, and the scope of the present invention is not intended to be limited thereto.

The method of testing the polyester resin and the tensile specimen of the following examples and comparative examples are as follows.

(1) Analysis of the fraction of diol component in the resin

In detail, the integral value of the peaks of the dicarboxylic acid and the polyfunctional carboxylic acid among the NMR peaks of the polyester resin was regarded as 100, and the relative intensity of the hydrogen peak of formaldehyde (oxymethylene) of each diol was obtained to calculate the molar concentration at this time, 600MHz NMR (JEO L) was used as an NMR instrument, and CDCl was used as the NMR instrument₃Is used as a solvent.

(2) Intrinsic Viscosity (IV)

The polyester resin was dissolved in o-chlorophenol at a concentration of 0.12% at 150 ℃ and measured in a constant temperature bath at 35 ℃ using a viscometer of the Ubbelohde type.

(3) Number average molecular weight (Mn)

The number average molecular weight was determined by the following method using gel permeation chromatography (GPC, Tosoh). Shodex L F804X 2 was used as a GPC column, and a Refractive Index (RI) detector was used as a detector.

0.03g of polyester resin was dissolved in 3m L of o-chlorophenol at 150 ℃ for 15min, and then 9m L of chloroform was added at room temperature to prepare a sample a solution of o-chlorophenol: chloroform ═ 1:3(v/v) of 12m L was used as an eluent, and measurement was performed by injecting the sample at 40 ℃ at a flow rate of 0.7 ml/min.

(4) Heat resistance (Tg)

The polyester resin was annealed at 300 ℃ for 5min and cooled to room temperature, and then Tg was measured during the 2 nd scan at a heating rate of 10 ℃/min.

(5) Color b (color b)

Measurements were performed using the Colorgard system available from Pacific Scientific Company.

(6) Haze (%)

A film sample of the copolymerized polyester resin composition was aged at a temperature of 23 ℃ and a RH humidity of 65% for 24 hours, and then haze (%) of three different positions of the film sample was measured using a haze meter (device name: NDH2000, manufacturer: nippon denzeoku (japan)) according to JIS (japanese industrial standards) K7136, and an average value of each measurement result was calculated as a result value.

(7) Tensile strength and Young's modulus

Tensile specimens (width of 0.4cm, length of 3cm, thickness of 0.2cm, type ISO527-21 BB) of the polyester resins were molded using a bay injection molding machine (bay injection molding machine) under conditions of a molding temperature of 30 ℃, an injection time of 3s, a dwell time of 5s, and a cooling time of 10s at a barrel temperature of 230 ℃ and a barrel temperature of 600kgf/cm²And then tensile strength and young's modulus were measured using UTM.

Examples 1 to 7

In a 5L reactor equipped with a stirrer and an outlet condenser, raw materials, i.e., dimethyl terephthalic acid (DMT), Isosorbide (ISB), 1, 4-Cyclohexanedimethanol (CHDM), and 1, 2-propanediol (1,2-PD) were injected in accordance with the contents of table 1 below, triethyl phosphate (TEP) as a phosphorus-based stabilizer and dibutyl tin oxide (DBTO) as a catalyst were added thereto in accordance with the contents of table 1 in accordance with each central atom with respect to the total weight of the raw materials, and then pressurized to 2.0kg/cm with nitrogen gas²And allowing the reaction while raising the temperature of the reactor to 220 ℃ to 250 ℃.

At this time, the produced methanol was discharged from the system, followed by transesterification. When the generation and discharge of methanol were finished, the reaction product was transferred to a polycondensation reactor equipped with a stirrer, a cooling condenser and a vacuum system to perform polycondensation, and the polymerization was terminated when the intrinsic viscosity of the reaction product reached its maximum value.

Comparative example 1 to comparative example 7

Polyester resins were prepared in the same manner as in examples 1 to 7, except that Ethylene Glycol (EG) was used instead of 1, 2-propanediol, and the raw materials were injected according to the contents in table 2 below.

[ TABLE 1]

[ TABLE 2 ]