TWI831977B - Polyester resin blend - Google Patents

Abstract

The present disclosure relates to a polyester resin blend. The polyester resin blend exhibits excellent miscibility even if it contains recycled polyethylene terephthalate as well as virgin polyethylene terephthalate, and can provide molded articles with high transparency.

Description

polyester resin blend

The present invention relates to a polyester resin blend.

In recent years, discarded plastics account for about 70% of marine pollution and have become a serious social problem. While regulating the use of disposable plastics, every country also promotes the reuse of discarded plastics. Currently, waste plastics can be collected, crushed and cleaned, then melted, extruded and re-pelletized for reuse as raw materials. However, since waste plastics contain foreign matter, it is difficult to provide high-quality plastic products. Therefore, there is an urgent need for research into producing high-quality plastic products from waste plastics.

[Patent document]

Japanese Patent No. 4771204

The present invention aims to provide polyester resin blends with good transparency and processability.

The invention provides a polyester resin blend, which contains polyparaphenylene Ethylene diformate, a first polyester resin and a second polyester resin. The first polyester resin has a structure in which an acid moiety derived from a dicarboxylic acid or a derivative thereof and a diol moiety derived from a diol containing ethylene glycol and a comonomer are repeated in in this structure. The first polyester resin is obtained by polymerizing carboxylic acid or a derivative thereof and a glycol containing ethylene glycol and a comonomer including isosorbide. The second polyester resin has a structure in which an acid moiety derived from a dicarboxylic acid or a derivative thereof and a diol moiety derived from a diol containing cyclohexanedimethanol are repeated. The second polyester resin is obtained by polymerizing dicarboxylic acid or a derivative thereof and a diol containing cyclohexane dimethanol (cyclohexane dimethanol).

According to a specific example of the present invention, even if the polyester resin blend contains recycled polyethylene terephthalate and virgin polyethylene terephthalate, it can still show good mutual solubility, and can provide products with High transparency moldings.

Hereinafter, a polyester resin blend of a specific embodiment of the present invention will be described.

The terms used below are only for describing individual specific examples and are not intended to limit the content of the present invention. The singular may also include the plural unless the context clearly indicates otherwise. In this disclosure, the terms "comprising", "comprising", etc. may be used to designate certain features, regions, integers, steps, etc. steps, operations, elements and/or components without excluding other existing or additional features, regions, integers, steps, operations, elements and/or components.

According to a specific example of the present invention, a polyester resin blend comprising polyethylene terephthalate, a first polyester resin and a second polyester resin is provided. The first polyester resin has a structure in which an acid moiety derived from a dicarboxylic acid or a derivative thereof and a diol moiety derived from a diol containing ethylene glycol and a comonomer are repeated in in this structure. The first polyester resin is obtained by polymerizing carboxylic acid or a derivative thereof and a glycol containing ethylene glycol and a comonomer including isosorbide. The second polyester resin has a structure in which an acid moiety derived from a dicarboxylic acid or a derivative thereof and a diol moiety derived from a diol containing cyclohexanedimethanol are repeated. The second polyester resin is obtained by polymerizing dicarboxylic acid or a derivative thereof and a diol containing cyclohexane dimethanol (cyclohexane dimethanol).

In the present invention, the polyester resin can be obtained by polymerizing a dicarboxylic acid or a derivative thereof and a diol, and the polyester resin has a structure in which an acid moiety derived from a dicarboxylic acid or a derivative thereof and a diol derived from The diol portion of the alcohol appears repeatedly in this structure. When an isosorbide-containing diol is used as the diol to include a diol moiety derived from isosorbide, it may be referred to as a first polyester resin, whereas when an isosorbide-containing diol is used instead of isosorbide When the diol as a diol includes a diol moiety derived from cyclohexanedimethanol, it may be referred to as a second polyester resin.

"Dicarboxylic acid or derivatives thereof" used herein refers to at least one compound selected from dicarboxylic acids and dicarboxylic acids. In addition, the term "derivatives of dicarboxylic acids" refers to alkyl esters of dicarboxylic acids (low alkyl esters with 1 to 4 carbon atoms, such as monomethyl ester, monoethyl ester, dimethyl ester , diethyl ester, dibutyl ester, etc.) or dicarboxylic anhydride. Thus, for example, terephthalic acid or its derivatives typically contain Diols react to form compounds with a terephthaloyl moiety, such as terephthalic acid, mono- or dialkyl terephthalates, and terephthalic anhydride.

In the present invention, the acid moiety and the diol moiety refer to the residues remaining after the dicarboxylic acid or its derivative is polymerized with the diol to remove hydrogen, hydroxyl or alkoxy groups therefrom.

Polyethylene terephthalate is widely used commercially due to its low price and excellent physical/chemical properties. However, due to its high crystallinity, it requires higher temperatures during processing and is limited in providing transparent products due to its high crystallization rate. Therefore, a technique is currently used in which a polyester resin containing a diol moiety derived from a comonomer, such as cyclohexanedimethanol, is blended with polyethylene terephthalate. However, due to structural differences between polyester resin and polyethylene terephthalate, polyester resin cannot exhibit good mutual solubility due to its lower transesterification level.

The inventors of the present invention have conducted research to solve the above-mentioned problems, and found that polyester terephthalate and a second polyester resin containing a diol moiety derived from cyclohexanedimethanol are combined with a second polyester resin containing a diol moiety derived from cyclohexanedimethanol. The present invention is accomplished by blending the first polyester resin from the diol moiety of isosorbide to improve the level of transesterification and provide a transparent polyester resin blend with good processability.

Polyester resin blends will be described in detail below.

According to this specific example, the first polyester resin may be blended with various commonly used polyethylene terephthalates and the second polyester resin to improve its transparency and processability.

Therefore, the type of polyethylene terephthalate used is not limited. For example, polyethylene terephthalate can be prepared by polymerizing dicarboxylic acid or its derivatives and diol, wherein the dicarboxylic acid or its derivatives can mainly be terephthalic acid (terephthalic acid) or its derivatives. Derivatives, and the glycol can mainly be ethylene glycol.

Polyethylene terephthalate may include acid moieties derived from comonomers other than terephthalic acid or derivatives thereof. Specifically, the comonomer may be selected from the group consisting of C8 to C14 aromatic dicarboxylic acid or its derivatives and C4 to C12 aliphatic dicarboxylic acid or its derivatives. At least one of the groups. Examples of C8 to C14 aromatic dicarboxylic acids or derivatives thereof may include aromatic dicarboxylic acids or derivatives thereof generally used in the manufacture of polyester resins, such as naphthalene dicarboxylic acid (e.g., m- Phthalic acid, dimethyl isophthalate, phthalic acid, dimethyl phthalate, phthalic acid anhydride ), 2,6-naphthalene dicarboxylic acid, etc.), dialkylnaphthalene dicarboxylate (such as dimethyl 2,6-naphthalene dicarboxylate) naphthalene dicarboxylate, etc.), diphenyl dicarboxylic acid (diphenyl dicarboxylic), etc. Examples of C4 to C12 aliphatic dicarboxylic acids or derivatives thereof may include linear, branched or cyclic aliphatic dicarboxylic acids or derivatives thereof generally used in the manufacture of polyester resins, such as cyclohexane cyclohexane dicarboxylic acid (such as 1,4-cyclohexane dicarboxylic acid, 1,3-cyclohexane dicarboxylic acid, etc.), Cyclohexane dicarboxylate (such as dimethyl 1,4-cyclohexane dicarboxylate, dimethyl 1,3-cyclohexanedicarboxylate) ,3-cyclohexane dicarboxylate, etc.), sebacic acid, succinic acid, isodecylsuccinic acid, maleic acid, maleic anhydride, trans Man Fumaric acid, adipic acid, glutaric acid, azelaic acid, etc. The amount of comonomer used may be 0 to 50 mol%, 0 to 30 mol%, 0 to 20 mol% or 0 to 10 mol% based on the total amount of dicarboxylic acid or derivatives thereof.

Polyethylene terephthalate may contain glycol moieties derived from comonomers other than ethylene glycol. Specifically, the comonomer may be an aromatic diol having 8 to 40 or 8 to 33 carbon atoms, an aliphatic diol having 2 to 20 or 2 to 12 carbon atoms, or a mixture thereof. Examples of aromatic diols may include ethylene oxide and/or derivatives of bisphenol A with the addition of propylene oxide, such as polyoxyethylene-(n)-2,2- Bis(4-hydroxyphenyl)propane (polyoxyethylene-(n)-2,2-bis(4-hydroxyphenyl)propane), polyoxypropylene-(n)-2,2-bis(4-hydroxyphenyl)propane (polyoxypropylene-(n)-2,2-bis(4-hydroxyphenyl)propane) or polyoxypropylene-(n)-polyoxyethylene-(n)-2,2-bis(4-hydroxyphenyl)propane ( polyoxypropylene-(n)-polyoxyethylene-(n)-2,2-bis(4-hydroxyphenyl)propane), where n is the number of units of polyoxyethylene or polyoxypropylene and can be 0 to 10. Examples of aliphatic glycols may include linear, branched or cyclic aliphatic glycols such as diethylene glycol, triethylene glycol, propanediol (eg 1,2- Propylene glycol, 1,3-propanediol, etc.), 1,4-butanediol (1,4-butanediol), pentanediol (pentanediol), hexanediol (such as 1,6-hexanediol, etc.), Neopentyl glycol (2,2-dimethyl-1,3-propanediol), 1,2-cyclohexanediol (1,2-cyclohexanediol), 1,4-cyclohexanediol (1 ,4-cyclohexanediol), 1,2-cyclohexanedimethanol (1,2-cyclohexanedimethanol), 1,3-cyclohexanedimethanol (1,3-cyclohexanedimethanol), 1,4-cyclohexanedimethanol ( 1,4-cyclohexanedimethanol), tetramethyl cyclobutanediol (tetramethyl cyclobutanediol), etc. The comonomer may be used in an amount of 0 to 50 mol%, 0 to 30 mol%, 0 to 20 mol% or 0 to 10 mol% based on the total amount of glycol.

According to the above specific examples, the first polyester resin can not only supplement the physical properties of the blend of virgin polyethylene terephthalate and the second polyester resin, but also can combine the recycled polyethylene terephthalate and the second polyester resin. The poor physical properties of blends of dimer resins, such as low transparency, are elevated to very good levels.

Recycled polyethylene terephthalate may be considered to include all polyethylene terephthalate collected or obtained after use. Specifically, recycled polyethylene terephthalate can be obtained by separating waste plastics according to certain standards, crushing and washing them, and then re-pelletizing them through melt extrusion, or it can be obtained by collecting waste plastics. It is obtained by depolymerizing plastic to the monomer grade and repolymerizing it. Depending on the manufacturing method, the recycled polyethylene terephthalate may be used after re-granulation and crystallization, or may be used after crystallization and subsequent condensation polymerization in the solid state.

Recycled polyethylene terephthalate, which is produced by depolymerizing waste plastic to monomer levels and then polymerizing it, can exhibit good properties and is indistinguishable from virgin polyethylene terephthalate. However, recycled polyethylene terephthalate obtained by re-granulating waste plastic has lower transparency than virgin polyethylene terephthalate and has a very fast crystallization rate, resulting in even if the recycled polyethylene terephthalate is recycled Ethylene terephthalate, alone or mixed with virgin polyethylene terephthalate, also makes it difficult to produce clear containers of appropriate thickness.

However, a blend of the first polyester resin with recycled polyethylene terephthalate and the second polyester resin according to a specific example exhibits excellent mutual solubility and thus can provide a product with high transparency and good processability. Polyester resin blend. In particular, since the first polyester resin according to a specific example is highly miscible with the recycled polyethylene terephthalate and the second polyester resin, it is possible to provide high-quality molded products without other additives. .

Therefore, virgin polyethylene terephthalate, recycled polyethylene terephthalate, or mixtures thereof may be used as polyethylene terephthalate.

In particular, in recycled polyethylene terephthalate, the polyester resin blend according to one embodiment may exhibit an intrinsic viscosity of 0.6 to 0.8 deciliters per gram (dl/g). High transparency and excellent processability.

In addition, the polyester resin blend according to the above specific examples can exhibit high transparency and good processability by including a resin containing greater than or equal to 95 mol% of the acid moiety derived from terephthalic acid and greater than or equal to 95 mol% of the glycol moiety derived from ethylene glycol. Since the resin may be a homopolymer made of terephthalic acid and ethylene glycol, the upper limit of the acid part derived from terephthalic acid and the diol part derived from ethylene glycol may be 100 mol%. When the acid moiety derived from terephthalic acid or the glycol moiety derived from ethylene glycol is less than 100 mol %, the acid moiety or glycol moiety derived from the above-described comonomer may be included within 5 mol %. In particular, the acid moiety derived from isophthalic acid and/or the diol moiety derived from cyclohexanedimethanol may be included within 5 mol% respectively.

The polyester resin blend may include recycled polyethylene terephthalate with a crystallization temperature of 130°C to 160°C to exhibit good processability.

The polyester resin blend may include recycled polyethylene terephthalate having a melting temperature of 250°C or higher to provide a polyester resin blend having a melting temperature that is easily processed.

According to this specific example, blending the first polyester resin with polyethylene terephthalate and the second polyester resin can be advantageous to make the first polyester resin have high transparency, so as to provide a product with high transparency. Moldings. Specifically, when measured according to ASTM D1003-97 on a 6 mm thick sample, the haze of the polyester resin can be less than or equal to 5%, less than or equal to 4.5%, less than or equal to 4%, less than or equal to 3.5%, Less than or equal to 3%, less than or equal to 2.5%, or less than or equal to 2%. Theoretically, since the optimal haze can be 0%, the lower limit can be 0% or above.

When measured after crystallization at 180°C for 100 minutes, the melting temperature of the first polyester resin may be 210 to 245°C, 220 to 240°C, or 230 to 235°C, allowing it to be melted with polyterephthalic acid Ethylene glycol and a second polyester resin are blended to exhibit good processability.

The first polyester resin has crystalline properties and amorphous properties, and may exhibit crystalline properties or amorphous properties depending on the environment. The first polyester resin may be a crystalline resin exhibiting crystallinity in the case of manufacturing, processing, or molding the polyester resin blend. However, the present invention is not limited thereto. As long as it can achieve desired properties by blending with polyethylene terephthalate and the second polyester resin, the first polyester resin may be an amorphous resin.

For example, by blending with polyethylene terephthalate and a second polyester resin, the first polyester resin can be a crystalline resin and exhibit good processability, and its crystallization half-life can be from 7 to 95 minutes, 7 to 80 minutes, 7 to 70 minutes, 7 to 60 minutes, 10 to 95 minutes, 30 to 95 minutes, 40 to 95 minutes, 10 to 80 minutes, 30 to 70 minutes, 30 to 60 minutes or 40 to 60 minutes.

The first polyester resin includes a glycol portion derived from a glycol containing ethylene glycol and a comonomer, and the glycol portion derived from the comonomer may be 5 to 20 mol % based on the total amount of the glycol portion. In addition, since the comonomer may contain isosorbide (1,4:3,6-dianhydroglucitol), the above-mentioned properties may be exhibited.

When the diol portion derived from the comonomer is less than 5 mol%, it is difficult to improve the processability of the polyethylene terephthalate and the second polyester resin to a suitable level. When the glycol portion derived from the comonomer exceeds 20 mol%, the first polyester resin may exhibit amorphous properties and be easily melted during processing or molding. In addition, unlike polyethylene terephthalate and The miscibility of the second polyester resin will be reduced.

The first polyester resin may comprise 5 to 15 mol%, 7 to 15 mol%, 8 to 15 mol%, 10 to 15 mol%, 9 to 12 mol%, or 10 to 12 mol% derived from the copolymer based on the total amount of the glycol moiety. The glycol portion of the monomer to exhibit better miscibility with recycled polyethylene terephthalate and the secondary polyester resin.

The first polyester resin essentially contains a glycol moiety derived from isosorbide as a glycol moiety derived from a comonomer, and this structure may improve its compatibility with polyethylene terephthalate and the second polyester resin of mutual solubility.

The first polyester resin may comprise 0.1 to 15 mol%, in particular 0.1 to 12 mol%, 3 to 12 mol%, 5 to 12 mol% or 7 to 11 mol% of isosorbide-derived in terms of the total amount of the glycol moiety. glycol moiety to maximize the properties mentioned above.

At the same time, the comonomers other than ethylene glycol can also comprise cyclohexanedimethanol in addition to isosorbide. Cyclohexane dimethanol may be used in an amount of 0.1 to 15 mol% based on the total amount of the glycol moiety to provide a first polyester resin having the above properties.

When isosorbide and cyclohexanedimethanol are used as comonomers, they can be used in a ratio of 1:2~5 mol (mol) or 1:2~4 mol to ensure better physical properties.

Comonomers other than ethylene glycol may include glycols generally used in the manufacture of polyester resins in addition to the above-mentioned monomers. Specific examples of glycols may include the glycols listed above for polyethylene terephthalate. However, it is advantageous for the comonomer other than ethylene glycol to be isosorbide or a combination of isosorbide and cyclohexanedimethanol to satisfy the above physical properties. When the comonomer includes diols other than isosorbide and cyclohexanedimethanol, the content may be less than or equal to 10 mol%, less than or equal to 5 mol%, or less than or equal to 2 mol% based on the total amount of the comonomer.

In the first polyester resin, similar to the above-mentioned polyethylene terephthalate, the dicarboxylic acid or its derivatives may mainly be terephthalic acid or its derivatives, and the polyester resin may contain other than terephthalate. Comonomers other than formic acid or its derivatives. The type and content of comonomers can be adjusted by referring to the types and content of comonomers that can be used for polyethylene terephthalate as mentioned above.

The second polyester resin according to this embodiment includes a glycol moiety derived from a glycol containing cyclohexanedimethanol. The first polyester resin according to this embodiment can improve the mutual solubility of various second polyester resins including diol moieties derived from a wide range of cyclohexanedimethanols to provide a polyester resin with good processability Blends. Accordingly, the second polyester resin may comprise from 0.1 mol % to 100 mol % of diol moieties derived from cyclohexanedimethanol, based on the total amount of glycol moieties, and the remaining glycol moieties may be derived from ethylene glycol. Diol portion of alcohol. However, the present invention is not limited thereto and may include a glycol moiety derived from glycols commonly used in the manufacture of polyester resins. Specific examples of glycols may include the glycols listed above for polyethylene terephthalate. When the second polyester resin contains derivatives other than cyclohexane When the glycol portion of a glycol other than dimethanol and ethylene glycol is used, the content may be less than or equal to 10 mol%, less than or equal to 5 mol%, or less than or equal to 2 mol% based on the total amount of the glycol portion.

Meanwhile, polyester resins produced by polymerizing dicarboxylic acids or derivatives thereof and glycols containing ethylene glycol may contain a glycol moiety derived from diethylene glycol, which can be obtained by using Two ethylene glycols react to form diethylene glycol, which is introduced by reacting diethylene glycol with a dicarboxylic acid or derivative thereof. Therefore, unless otherwise stated, a glycol moiety derived from ethylene glycol may be considered to include a glycol moiety derived from diethylene glycol.

In the second polyester resin, the dicarboxylic acid or its derivatives may mainly be terephthalic acid or its derivatives, such as the above-mentioned polyethylene terephthalate, and the polyester resin may contain other than terephthalic acid. or comonomers other than its derivatives. The type and content of comonomers can be adjusted by referring to the types and content of comonomers that can be used for polyethylene terephthalate as mentioned above.

Polyester resin blends according to this embodiment may include two or more polyester resins containing varying amounts of a diol moiety derived from cyclohexanedimethanol as the second polyester resin. .

For example, the polyester resin blend may include a third polyester resin and a fourth polyester resin, wherein the third polyester resin contains greater than or equal to 0.1 mol% and less than 50 mol based on the total amount of glycol moiety. % of the glycol moieties derived from cyclohexanedimethanol, and the fourth polyester resin contains greater than or equal to 50 mol% of the glycol moieties derived from cyclohexanedimethanol based on the total amount of glycol moieties.

The third polyester resin can improve the transparency of the polyester resin blend, and with the total glycol portion In terms of amount, it may contain less than or equal to 40 mol%, less than or equal to 35 mol%, less than or equal to 31 mol%, or less than or equal to 30 mol%, and greater than or equal to 0.1 mol%, greater than or equal to 5 mol%, greater than or equal to 10 mol%, Greater than or equal to 15 mol%, greater than or equal to 20 mol%, or greater than or equal to 25 mol% of the diol moiety derived from cyclohexanedimethanol.

In addition, the fourth polyester resin may contain greater than or equal to 50 mol% or greater than or equal to 55 mol% and less than or equal to 100 mol% or less than or equal to 60 mol% derived from cyclohexanedimethanol in terms of the total amount of the glycol moiety. of the glycol part.

Since the first polyester resin can improve the miscibility with polyethylene terephthalate and the second polyester resin, the content of the diol moiety derived from cyclohexanedimethanol contained in the second polyester resin is irrelevant, so the polyester resin blend may include a variety of second polyester resins to achieve desired physical properties.

At the same time, the first polyester resin and the second polyester resin can be esterified or transesterified by performing an esterification reaction or a transesterification reaction on the above-mentioned dicarboxylic acid or a derivative thereof and the above-mentioned diol. It is prepared by subjecting the product obtained from the reaction to polycondensation reaction. Hereinafter, a method of manufacturing a polyester resin will be described in detail as an example of a method of manufacturing the first polyester resin and the second polyester resin.

Catalysts can be used in the esterification reaction or transesterification reaction. The catalyst may include sodium and magnesium methylates, acetates, borates, fatty acids or carbonates of zinc, cadmium, manganese, cobalt, calcium, barium, etc., such as magnesium Metals and oxides of lead, zinc, antimony, germanium, etc.

The esterification reaction or transesterification reaction can be carried out in a batch, semi-continuous or continuous manner. Each raw material can be added separately, but it is preferably added to mix the dicarboxylic acid or its derivative with the glycol. of slurry.

Polycondensation catalysts, stabilizers, colorants, crystallizers, antioxidants, branching agents, etc. can also be added to the slurry before the esterification reaction or transesterification reaction or the product after the reaction is completed.

However, the timing of adding the above additives is not limited thereto. The above additives can be added at any time during the preparation of the polyester resin. At least one of conventional titanium-based, germanium-based, antimony-based, aluminum-based, and tin-based compounds can be appropriately selected and used as the polycondensation catalyst. Preferred examples of titanium-based catalysts include tetraethyl titanate, acetyltripropyl titanate, tetrapropyl titanate, tetrabutyl titanate ), polybutyl titanate, 2-ethylhexyl titanate, octylene glycol titanate, lactate titanate, triethanolamine titanate (triethanolamine titanate), acetylacetonate titanate, ethyl acetoacetic ester titanate, isostearyl titanate, titanium oxide, titanium dioxide/dioxide Silicon oxide copolymer, titanium dioxide/zirconium oxide copolymer, etc. In addition, preferred examples of germanium-based catalytic bases include germanium oxide (germanium oxide) and its copolymers. Phosphorus-based compounds such as phosphoric acid, trimethyl phosphate and triethyl phosphate can usually be used as stabilizers, and the addition of stabilizers is based on the total weight of the final polymer (polyester resin). Amounts can range from 10 to 200 ppm, based on phosphorus atoms. When the content of the stabilizer is less than 10 ppm, the polyester resin may not be stable enough, and the color of the polyester resin may be yellowish. When the content of the stabilizer is greater than 200 ppm, a polymer with a high degree of polymerization may not be obtained. Furthermore, examples of colorants added to improve the color of the polymer may include conventional cobalt-based colorants such as cobalt acetate, cobalt propionate, and the like. The colorant can be added at a content of 1 to 200 ppm based on cobalt atoms based on the total weight of the final polymer (polyester resin). like If necessary, anthraquinone-based compounds, perinone-based compounds, azo-based compounds and methine-based compounds can be used as organic compounds. Compound colorants. Examples of commercially available products may include toners such as Polysynthrene Blue RLS manufactured by Clarient Corporation or Solvaperm Red BB manufactured by Clarient Corporation. The organic compound colorant may be added in an amount of 0 to 50 ppm based on the total weight of the final polymer. When the colorant is used in an amount outside the above range, the yellow color of the polyester resin may not be sufficiently hidden, or the physical properties may be deteriorated.

Examples of crystallization aids may include crystal nucleating agents, ultraviolet absorbers, polyolefin-based resins, polyamide resins, and the like. Examples of antioxidants may include hindered phenolic antioxidants, phosphite-based antioxidants, thioester-based antioxidants, and mixtures thereof. The branching agent may include conventional branching agents having at least three functional groups, examples of which may include trimellitic anhydride, trimethylol propane, trimellitic acid, or mixtures thereof.

In addition, the esterification reaction can be performed at a pressure of 0 to 10.0kgf/cm ² (0 to 7355.6 millimeters of mercury (mmHg)), 0 to 5.0kgf/cm ² (0 to 3677.8mmHg), or 0.1 to 3.0kgf/cm ² ( 73.6 to 2206.7 mmHg) at a temperature of 200 to 300°C or 230 to 280°C. The transesterification reaction can be performed at ¹⁵⁰ to 270°C or ¹⁸⁰ to a temperature of 260°C. The pressure outside the brackets refers to gauge pressure (expressed in kgf/ ^cm2 ), while the pressure inside the brackets refers to absolute pressure (expressed in mmHg).

When the reaction temperature and pressure deviate from the above ranges, the physical properties of the polyester resin may be deteriorated. The reaction time (average residence time) is usually from 1 hour to 24 hours or from 2 hours to 8 hours, which can depend on the reaction temperature, pressure and the molar ratio of the diol relative to the dicarboxylic acid or derivative thereof. The ratio changes.

The product obtained from the esterification reaction or transesterification reaction can be prepared into a polyester resin with a high degree of polymerization through a polycondensation reaction. The polycondensation reaction is usually carried out under reduced pressure of 400 to 0.01 mmHg, 100 to 0.05 mmHg or 10 to 0.1 mmHg at a temperature of 150°C to 300°C, 200°C to 290°C or 260°C to 290°C. Pressure here refers to absolute pressure. Reduced pressure conditions of 400 to 0.01 mmHg are used to remove reaction by-products and unreacted materials. Therefore, if the reduced pressure conditions deviate from the above range, by-products and unreacted materials may not be sufficiently removed. Furthermore, when the reaction temperature of the polycondensation reaction deviates from the above range, the physical properties of the polyester resin may be deteriorated. The polycondensation reaction will proceed for a period of time until the desired intrinsic viscosity is reached. For example, the average residence time may be from 1 hour to 24 hours.

The intrinsic viscosity of the polymer obtained after the polycondensation reaction is suitably 0.30 dl/g to 1.0 dl/g. When the intrinsic viscosity is less than 0.30dl/g, the reaction rate of solid phase reaction may be significantly reduced. When the intrinsic viscosity exceeds 1.0dl/g, the viscosity of the molten material may increase during the melt polymerization process, and the possibility of discoloration of the polymer increases due to the shear stress between the stirrer and the reactor. And produce by-products such as acetaldehyde.

If necessary, the polyester resin can have a higher degree of polymerization by further performing a solid phase reaction after the polycondensation reaction.

Specifically, the polymer obtained by the polycondensation reaction can be discharged from the reactor to produce into particles. The method of making pellets can be the strand cutting method in which the polymer is extruded into strands and solidified in the coolant and then cut with a cutting machine, or the die holes are immersed in the coolant and the polymer is The underwater cutting method is to extrude directly into the coolant and then cut with a cutting machine. In the strand cutting method, the coolant is generally maintained at a low temperature so that the strands are fully solidified to avoid cutting problems. In the underwater cutting method, it is better to maintain the temperature of the coolant to match the polymer so that the shape of the polymer is consistent. However, in the case of crystalline polymers, the temperature of the coolant may be intentionally maintained at a high temperature, thereby inducing crystallization during discharge.

Through the cleaning of granular polymers, there is an opportunity to remove raw materials dissolved in water in unreacted raw materials. Since the surface area of the particle at a given weight increases as particle size decreases, smaller particle sizes are advantageous. To this end, the particles may be prepared to have an average weight of about less than or equal to 15 milligrams (mg). For example, water washing can be performed by placing the particulate polymer in water at a temperature equal to or about 5 to 20° C. below the glass transition temperature of the polymer for 5 minutes to 10 hours.

The granular polymer is first subjected to a crystallization step to prevent fusion during the solid phase reaction. The crystallization step may be carried out in the atmosphere, in the atmosphere of an inert gas, water vapor, an inert gas containing water vapor, or in a solution at a temperature of 110 to 210°C or 120 to 210°C. When temperatures are low, granular crystals form very slowly. When temperatures are high, the particle surfaces melt faster than the crystals can form, causing the particles to stick to each other, resulting in fusion. Since the heat resistance of the particles increases as the particles crystallize, the particles can also be crystallized by dividing the crystallization process into several steps and gradually increasing the temperature.

The solid phase reaction can be carried out in an environment of inert gas such as nitrogen, carbon dioxide or argon, or under reduced pressure of 400 to 0.01mmHg at 180 to 220°C. temperature, with an average residence time of 1 hour to 150 hours. Through this solid-phase reaction, the molecular weight can be further increased, and unreacted raw materials remaining in the melting reaction, as well as cyclic oligomers and acetaldehyde produced during the reaction can be removed.

The solid phase reaction can be carried out until the intrinsic viscosity of the crystallized polymer reaches greater than or equal to 0.65dl/g, greater than or equal to 0.70dl/g, greater than or equal to 0.75dl/g, or greater than or equal to 0.80dl/g, where the intrinsic viscosity It is measured at 35°C after dissolving the polymer in o-chlorophenol at a concentration of 1.2g/dl for 15 minutes at 150°C.

Since the first polyester resin can improve the transparency and processability of the polyethylene terephthalate and the second polyester resin blended in various proportions, the polyethylene terephthalate can be blended in various proportions. ester, a first polyester resin and a second polyester resin to provide a polyester resin blend to achieve desired properties. For example, the polyester resin blend may contain greater than or equal to 5 wt%, greater than or equal to 10 wt%, or greater than or equal to 15 wt% and less than or equal to 50 wt%, less than or equal to 40 wt%, or less based on total solids. or equal to 30wt% of polyethylene terephthalate, greater than or equal to 5wt%, greater than or equal to 10wt%, greater than or equal to 15wt%, greater than or equal to 20wt%, or greater than or equal to 30wt% and less than or equal to 90wt%, Less than or equal to 80wt% or less than or equal to 70wt% of the first polyester resin and greater than or equal to 1wt%, greater than or equal to 5wt%, greater than or equal to 10wt% or greater than or equal to 20wt% and less than or equal to 80wt%, less than or Equal to 70wt%, less than or equal to 60wt%, or less than or equal to 50wt% of the second polyester resin. The total solids content is the total weight of the solid components contained in the polyester resin blend, and may be, for example, the total weight of polyethylene terephthalate, the first polyester resin and the second polyester resin.

When the polyester resin blend includes a third polyester resin and a fourth polyester resin as the second polyester resin When ester resin is used, in terms of total solids, it may include greater than or equal to 5wt%, greater than or equal to 10wt%, or greater than or equal to 15wt%, and less than or equal to 50wt%, less than or equal to 40wt%, or less than or equal to 30wt%. Polyethylene terephthalate, greater than or equal to 5wt%, greater than or equal to 10wt%, greater than or equal to 15wt%, greater than or equal to 20wt%, or greater than or equal to 30wt% and less than or equal to 90wt%, less than or equal to 80wt% Or less than or equal to 70wt% of the first polyester resin, greater than or equal to 1wt%, greater than or equal to 5wt%, greater than or equal to 10wt%, or greater than or equal to 20wt% and less than or equal to 80wt%, less than or equal to 70wt%, less than Or equal to 60wt% or less than or equal to 50wt% of the third polyester resin and greater than or equal to 1wt%, greater than or equal to 5wt%, greater than or equal to 10wt% or greater than or equal to 20wt% and less than or equal to 80wt%, less than or equal to 70wt%, less than or equal to 60wt%, or less than or equal to 50wt% of the fourth polyester resin.

At the same time, the polyester resin blend according to this specific example can exhibit good mutual solubility. In the present invention, the level of transesterification can be used to evaluate the miscibility of polyester resin blends. Specifically, transesterification can be confirmed by evaluating the melting temperature of the polyester resin blend during the first scan (called the first melting temperature) using differential scanning calorimetry (DSC). level. It can be estimated that when the first melting temperature is lower, the transesterification level between the polyester resins in the blend is higher, which represents good mutual solubility. However, when the first melting temperature is too low, the physical properties of the polyester resin blend will deteriorate, so the first melting temperature of the polyester resin blend is preferably 225 to 245°C, 225 to 242°C, 230 to 230°C. 242℃ or 230 to 240℃. Even if the polyester resin blend contains recycled polyethylene terephthalate, good processability can be exhibited by having the melting temperature within the above range.

Meanwhile, polyester resin blends can have haze of less than or equal to 5%, less than or equal to 4.5%, less than or equal to 4%, less than or equal to 4%, when measured according to ASTM D1003-97 on a 6 mm thick sample. A haze equal to 3.5%, less than or equal to 3%, less than or equal to 2.5%, less than or equal to 2%, or less than or equal to 1% represents high transparency. Theoretically, since the optimal haze can be 0%, the lower limit can be 0% or above.

Meanwhile, the polyester resin blend according to this embodiment may be crystalline or amorphous. When the polyester resin blend is amorphous, if necessary, it can be crystallized through a crystallization process to achieve crystallinity.

Even if the polyester resin blend according to this specific example includes recycled polyethylene terephthalate, the first polyester resin and the second polyester resin may have excellent mutual solubility with the recycled polyethylene terephthalate. , thus having the advantage of not requiring additives to complement the properties of recycled polyethylene terephthalate. However, as a non-limiting example, the polyester resin blend may contain additives commonly used in the art.

The polyester resin blend according to the above specific examples can provide for the production of molded articles having high transparency and good processability even if it includes recycled polyethylene terephthalate and virgin polyethylene terephthalate. .

The functions and effects of the present invention will be described in more detail below through specific embodiments. At the same time, these embodiments are only illustrative and therefore should not be construed as limiting the scope of the present invention.

The following physical properties were measured according to the following method.

(1)Intrinsic viscosity (IV)

After the sample was dissolved in o-chlorophenol at a concentration of 1.2g/dl at 150°C for 15 minutes, the intrinsic viscosity of the sample was measured using an Ubbelohde viscometer. Specifically, the temperature of the viscometer is maintained at 35°C, and the time required between the solvent passing through a specific internal area of the viscometer (outflow time, _t0 ) and the time required for the solution to pass through the viscometer (t) are measured, respectively. . Next, the outflow time t ₀ and time t are substituted into Equation 1 to calculate the specific viscosity (specific viscosity) η _sp , and the calculated specific viscosity is substituted into Equation 2 to calculate the intrinsic viscosity [η]

In Equation 2, A is the Huggins constant and is 0.247. c is the concentration and is 1.2g/dl.

(2) First melting temperature (Tm)

The first melting temperature of particles prepared from the polyester resin blend can be measured by differential scanning calorimetry. A DSC 1 model manufactured by Mettler Toledo was used as the measuring device. Specifically, the particles were dried in a nitrogen atmosphere at 65° C. for 6 to 12 hours using a dehumidification dryer (D2T manufactured by Moretto). Therefore, the melting temperature is measured when the remaining moisture in the particles is less than 500 ppm. Take out about 6 to 10 mg of dry particles and put them into an aluminum pan, maintain at 30°C for 3 minutes, heat from 30°C to 280°C at a rate of 10°C/min, and maintain at 280°C for 3 minutes (first time scan). Then, in In the first scan, DSC used the integration function in the TA menu in the related program (STARe software) provided by Mettler Toledo to analyze the peak value of the first melting temperature Tm. The temperature range of the first scan is set from the starting point minus 10°C to the temperature value corresponding to the peak of the first melting temperature Tm plus 10°C, and is calculated by the program.

(3)Visible haze

In order to confirm whether polyethylene terephthalate, the first polyester resin and the second polyester resin are well blended, the samples prepared from the polyester resin blend were visually observed in environments with and without light sources. Particle haze. When haze is not observed, it can be evaluated that the first polyester resin improves the mutual solubility between polyethylene terephthalate and the second polyester resin, and the polyester resin blend is well blended .

Specifically, the haze of the particles prepared from one of the Examples and Comparative Examples was visually observed. When no haze is observed and the particles are transparent, it can be marked as "no haze"; when haze is slightly observed, it can be marked as "slight haze"; and when haze is observed and the particles are opaque, it can be marked as "no haze". Can be marked as "Haze". When "slight haze" and "haze" cannot be clearly distinguished, the following criteria can be used for evaluation. When the color L value of the particles prepared from one of the Examples and Comparative Examples is measured via a colorimeter compared to the first polyester resin and the second polyester resin contained in the polyester resin blend When the color L value of the resin particle with the largest color L value rises less than 5, it can be marked as "slight haze", and when the rising value is greater than or equal to 5, it can be marked as "haze"

(4)6T haze

Samples with a thickness of 6 mm were prepared using the polyester resin blend, and the haze of the samples was measured using a CM-3600A manufactured by Minolta according to ASTM D1003-97.

Preparation Example 1: Preparation of the first polyester resin

Place 3189.1 grams (19.2 mol) of terephthalic acid, 1334.1 grams (21.5 mol) of ethylene glycol and 504.9 grams (3.5 mol) of isosorbide into a reactor with a volume of 10 liters (L), where the reactor It is connected with a pipe column and a condenser that can be cooled by water. 1.0 g of germanium dioxide was used as the catalyst, 1.46 g of phosphoric acid was used as the stabilizer, and 0.7 g of cobalt acetate was used as the colorant. Next, nitrogen gas was injected into the reactor to create a pressurized state, in which the pressure of the reactor was 1.0 kgf/cm ² higher than normal pressure (absolute pressure: 1495.6 mmHg).

Next, the temperature of the reactor was raised to 220°C over 90 minutes, maintained at 220°C for 2 hours, and raised to 260°C over 2 hours. After that, the reactor was maintained at 260°C, and the esterification reaction was performed until the mixture in the reactor became transparent when observed with the naked eye. When the esterification reaction is completed, the nitrogen in the pressurized reactor is discharged to the outside to reduce the pressure in the reactor to normal pressure, and then the mixture in the reactor is transferred to a volume of 7 liters capable of vacuum reaction. in the reactor.

Next, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) in 30 minutes, the temperature of the reactor was raised to 280°C in 1 hour, and the pressure of the reactor was maintained at 1 Torr (absolute pressure: 5 mmHg). : 1mmHg) or lower while performing the polycondensation reaction. In the initial stage of the polycondensation reaction, although the stirring rate is set high, as the polycondensation reaction proceeds or the temperature of the reactants rises above the set temperature, the viscosity of the reactants increases, causing the stirring force to weaken, you can Adjust mixing speed appropriately. The polycondensation reaction was carried out until the intrinsic viscosity (IV) of the mixture in the reactor (melted) became 0.50 dl/g. When the intrinsic viscosity of the mixture in the reactor reaches the desired level, the mixture is discharged to the outside of the reactor and stranded, then solidified with cooling liquid and granulated so that the average weight is about 12 to 14 mg. The particles thus obtained were left in water at 70° C. for 5 hours to remove unreacted raw materials contained in the particles.

The particles were left at 150° C. for 1 hour to crystallize and then added to a solid phase polymerization reactor with a volume of 20 liters. Afterwards, nitrogen gas was flowed into the reactor at a rate of 50 liters/minute (L/min). At this time, the temperature of the reactor was raised from room temperature to 140°C at a rate of 40°C/hour, and maintained at 140°C for 3 hours. Then, the temperature was raised to 200°C at a rate of 40°C/hour and maintained at 200°C. Solid-state polymerization was carried out until the intrinsic viscosity of the particles in the reactor reached 0.95 dl/g.

The content of the diol part derived from isosorbide was 10 mol% based on the total content of the diol part contained in the polyester resin.

Preparation Example 2: Preparation of the third polyester resin

Place 2950 grams (17.8 mol) of terephthalic acid, 1047 grams (16.9 mol) of ethylene glycol and 767.9 grams (5.3 mol) of 1,4-cyclohexanedimethanol into a reaction volume of 10 liters (L) In the reactor, the reactor is connected with a column and a condenser that can be cooled by water. 1.0 g of germanium dioxide was used as the catalyst, 1.46 g of phosphoric acid was used as the stabilizer, and 1.1 g of cobalt acetate was used as the colorant. Next, nitrogen gas was injected into the reactor to create a pressurized state, in which the pressure of the reactor was 1.0 kgf/cm ² higher than normal pressure (absolute pressure: 1495.6 mmHg).

Next, the temperature of the reactor was raised to 220°C over 90 minutes, maintained at 220°C for 2 hours, and raised to 250°C over 2 hours. Afterwards, the reactor was maintained at 250°C until the mixture in the reactor became transparent when observed with the naked eye. When the esterification reaction is completed, the nitrogen in the pressurized reactor is discharged to the outside to reduce the pressure in the reactor to normal pressure, and then the mixture in the reactor is transferred to a volume of 7 liters capable of vacuum reaction. in the reactor.

Next, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) in 30 minutes, the temperature of the reactor was raised to 265°C in 1 hour, and the pressure of the reactor was maintained at 1 Torr (absolute pressure: 5 mmHg). : 1mmHg) or lower while performing the polycondensation reaction. In the initial stage of the polycondensation reaction, although the stirring rate is set to a high level, as the polycondensation reaction proceeds or the temperature of the reactants rises above the set temperature, the viscosity of the reactants increases, causing the stirring force to weaken, you can Adjust mixing speed appropriately. The polycondensation reaction was carried out until the intrinsic viscosity (IV) of the mixture in the reactor (melted) became 0.80 dl/g. When the intrinsic viscosity of the mixture in the reactor reaches the desired level, the mixture is discharged to the outside of the reactor and stranded, then solidified with cooling liquid and granulated so that the average weight is about 12 to 14 mg. The particles thus obtained were left in water at 70° C. for 5 hours to remove unreacted raw materials contained in the particles.

The content of the diol part derived from 1,4-cyclohexanedimethanol was 30 mol% based on the total content of the diol part contained in the polyester resin.

Preparation Example 3: Preparation of the fourth polyester resin

Place 2951 grams (17.8 mol) of terephthalic acid, 827 grams (23.3 mol) of ethylene glycol and 1280 grams (8.9 mol) of 1,4-cyclohexanedimethanol into a reaction volume of 10 liters (L) In the reactor, the reactor is connected with a column and a condenser that can be cooled with water. 1.0 g of germanium dioxide was used as the catalyst, 1.46 g of phosphoric acid was used as the stabilizer, and 1.1 g of cobalt acetate was used as the colorant. Next, nitrogen gas was injected into the reactor to create a pressurized state, in which the pressure of the reactor was 1.0 kgf/cm ² higher than normal pressure (absolute pressure: 1495.6 mmHg).

Next, the temperature of the reactor was raised to 220°C over 90 minutes and maintained at 220°C for 2 hours. time, and take 2 hours to raise the temperature to 250°C. Afterwards, the reactor was maintained at 250°C until the mixture in the reactor became transparent when observed with the naked eye. When the esterification reaction is completed, the nitrogen in the pressurized reactor is discharged to the outside to reduce the pressure in the reactor to normal pressure, and then the mixture in the reactor is transferred to a volume of 7 liters capable of vacuum reaction. in the reactor.

Next, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) in 30 minutes, the temperature of the reactor was raised to 265°C in 1 hour, and the pressure of the reactor was maintained at 1 Torr (absolute pressure: 5 mmHg). : 1mmHg) or lower while performing the polycondensation reaction. In the initial stage of the polycondensation reaction, although the stirring rate is set to a high level, as the polycondensation reaction proceeds or the temperature of the reactants rises above the set temperature, the viscosity of the reactants increases, causing the stirring force to weaken, you can Adjust mixing speed appropriately. The polycondensation reaction was carried out until the intrinsic viscosity (IV) of the mixture in the reactor (melted) became 0.70 dl/g.

The content of the diol part derived from 1,4-cyclohexanedimethanol was 50 mol% based on the total content of the diol part contained in the polyester resin.

In the polyester resins prepared in Preparation Examples 1 to 3, except for the diol part derived from isosorbide and the diol part derived from 1,4-cyclohexanedimethanol, the remaining diol parts are Derived from ethylene glycol. The glycol moiety derived from ethylene glycol may comprise a glycol moiety derived from diethylene glycol by reacting two ethylene glycols to form diethylene glycol and reacting diethylene glycol with a dicarboxylic acid or derivative thereof And introduced.

Examples and Comparative Examples: Preparation of Polyester Resin Blends

The polyester resin prepared in one of Preparation Examples 1 to 3 was melt-blended with recycled PET at a weight ratio shown in the following Table 1 to prepare a polyester resin blend. Specifically, by crushing and cleaning waste The flakes obtained by discarding plastic are then granulated by melt extrusion to prepare recycled PET. Next, the recycled PET was blended with the polyester resin prepared in one of Preparation Examples 1 to 3 at a weight ratio shown in the following Table 1, and completely melted and extruded at about 260° C. to obtain granular polyester resin. Ester resin blends.

Recycled PET can have different compositions, which can depend on where the waste plastic is collected, how it is sorted and how it is re-pelletized. The recycled PET used in this experiment is a copolymer of terephthalic acid, isophthalic acid and ethylene glycol. In terms of the total amount of dicarboxylic acid, the content of isophthalic acid is within 3 mol%. The intrinsic viscosity (IV) of the copolymer is 0.75dl/g, the crystallization temperature is 130°C, and the melting temperature is 250°C.

(單位：以重量計)

(Unit: by weight)

Experimental Example: Physical Property Evaluation of Polyester Resin Blends

The physical properties of the particles of the polyester resin blend prepared above can be evaluated by the above method, and the results are shown in Table 2.

Referring to Table 2, it can be understood from Table 2 that when the first polyester resin containing the diol moiety derived from isosorbide is added to the polyester resin containing regenerated PET and containing the glycol moiety derived from cyclohexanedimethanol according to Comparative Examples 1 to 6 When the composition of the second polyester resin of the glycol moiety is as in Examples 1 to 7, or when the second polyester resin containing the glycol moiety derived from cyclohexanedimethanol is added according to Comparative Example 7 to When the composition of 9 includes recycled PET and a first polyester resin containing a diol moiety derived from isosorbide, as in Examples 8 to 10, the haze of the composition can be reduced, and the melting temperature of the composition can be adjusted to a range conducive to processing.

The above are only preferred embodiments of the present invention, and all equivalent changes and modifications made in accordance with the patentable scope of the present invention shall fall within the scope of the present invention.

Claims (12)

A polyester resin blend, including a polyethylene terephthalate; a first polyester resin having a structure derived from a carboxylic acid or a derivative thereof An acid moiety and a diol moiety derived from a diol containing ethylene glycol and a comonomer are repeated in the structure, and the first polyester resin is Obtained by polymerizing a dicarboxylic acid or a derivative thereof and a glycol containing ethylene glycol and a comonomer including isosorbide (isosorbibe); and a second polyester resin having a structure and derived from a dicarboxylic acid. An acid moiety of a carboxylic acid or its derivative and a diol moiety derived from a diol containing cyclohexanedimethanol are repeated in the structure. The second polyester resin is formed by polymerizing a dicarboxylic acid or its derivative. Derivatives obtained with glycols containing cyclohexanedimethanol; wherein the polyester resin blend has a haze of less than or equal to 5% when measured according to ASTM D1003-97 on a 6 mm thick sample . The polyester resin blend according to claim 1, wherein the polyethylene terephthalate is virgin polyethylene terephthalate, recycled polyethylene terephthalate or a mixture thereof . The polyester resin blend as claimed in claim 2, wherein the intrinsic viscosity of the recycled polyethylene terephthalate is 0.6 to 0.8 deciliters/gram (dl/g). The polyester resin blend of claim 2, wherein the recycled polyethylene terephthalate includes greater than or equal to 95 mole percent (mol%) of an acid moiety derived from terephthalic acid and greater than or equal to 95 mole percent of the monoglycol moiety derived from ethylene glycol. The polyester resin blend of claim 1, wherein the first polyester resin includes 5 to 20 mole percent of isosorbide derived from, based on the total amount of diol portions derived from diols. A glycol moiety of a comonomer. The polyester resin blend of claim 1, wherein the first polyester resin includes 0.1 to 15 mole percent of isosorbide-derived based on the total amount of the glycol portion derived from the glycol. One glycol moiety. The polyester resin blend of claim 5, wherein the comonomer further includes cyclohexanedimethanol. The polyester resin blend of claim 7, wherein the first polyester resin includes a diol portion derived from isosorbide and a portion derived from cyclohexanedimethanol in a molar ratio of 1:2~5 One glycol moiety. The polyester resin blend of claim 1, wherein the second polyester resin includes a third polyester resin and a fourth polyester resin, and based on the total amount of the glycol part, the third polyester resin The ester resin contains greater than or equal to 0.1 mole percent and less than 50 mole percent of a glycol moiety derived from cyclohexanedimethanol, and the fourth polyester resin contains greater than or equal to 50 mole percent of the monodiol moiety derived from cyclohexanedimethanol. The polyester resin blend of claim 1, wherein in terms of the total amount of solids, the polyester resin blend includes 5 to 50 weight percent (wt%) of polyethylene terephthalate, 5 to 90 % by weight of the first polyester resin and 1 to 80 % by weight of the second polyester resin. The polyester resin blend as claimed in claim 9, wherein in terms of the total amount of solids, the polyester resin blend includes 5 to 50 weight percent polyethylene terephthalate, 5 to 90 weight percent percentage of the first polyester resin, 1 to 80 weight percent of the third polyester resin, and 1 to 80 weight percent of the fourth polyester resin. The polyester resin blend as claimed in claim 1, wherein the polyester resin blend has a melting temperature of 225 to 245°C when measured in the first scan by differential scanning calorimetry.