KR100971905B1 - Copolyester resin Chemically Recycled from polyethylene terephthalate and Manufacturing method thereof - Google Patents

Abstract

The present invention relates to copolyester resins prepared by chemically regenerating polyethylene terephthalate products and to products made therefrom. In particular, it relates to a copolyester resin prepared by depolymerizing a polyethylene terephthalate product with ethylene glycol and adding an aromatic dieside or an ester forming derivative thereof represented by formula (1) thereto and a product produced therefrom.

ROOC-A-COOR ------------------------------- Formula (1)

(Wherein A represents an aromatic group such as benzene, naphthalene and anthracene, or an aromatic group containing a metal salt thereof, and R represents an alkyl group such as hydrogen or methyl or ethyl.)

Polyethylene Terephthalate, Copolyester, Chemical Regeneration, Glycolisis

Description

Copolyester polymer prepared by chemically regenerating polyethylene terephthalate and a method for manufacturing the same {Copolyester resin Chemically Recycled from poly (ethylene terephthalate) and Manufacturing method

Polyethylene terephthalate is widely used for various applications such as fibers, films and bottles due to its low cost, chemical resistance, excellent physical properties, and excellent durability. However, even after disposal, it does not decompose and thus becomes an environmental problem.

Therefore, various studies on the regeneration of polyethylene terephthalate are in progress, but the regeneration amount is still insignificant compared to the production amount.

The method of regenerating polyethylene terephthalate is divided into physical and chemical methods.

Physical methods consist of recovering heat by incineration and remelting again to make products. The method of recovering heat by incineration is the simplest method, but carbon dioxide generated during combustion may cause global warming problems. The method of making a product by remelting is difficult to apply to the use of fibers, films, bottles, etc., which requires uniformity of physical properties due to the purity of the discarded polyethylene terephthalate is used for the production of low quality products by injection.

As the chemical method, there are known a glycolysis method for depolymerization using glycol, a hydrolysis method for hydrolysis with an alkaline solution, and an alcoholicsis for decomposition using alcohol such as methanol.

The glycolysis method is a method of preparing oligomers by depolymerization using glycols such as ethylene glycol or propylene glycol, and repolymerizing them or preparing a polyol which is applied for use such as unsaturated polyester resin. Known.

The hydrolysis method is a method of recovering terephthalic acid and ethylene glycol, which are raw materials of polyethylene terephthalate, by hydrolysis with a strong alkaline aqueous solution such as sodium hydroxide or gallium hydroxide.

Alcoholicis is a method of recovering dimethyl terephthalate, diethyl terephthalate and ethylene glycol by decomposing with an alcohol such as methanol or ethanol.

Currently, the glycolysis method of recovering and repolymerizing an oligomer and the alcoholissis method of recovering dimethyl terephthalate or diethyl terephthalate are applied.

Dimethyl terephthalate or diethyl terephthalate regenerated by the alcoholissis method has a disadvantage that it is difficult to apply to the polymerization process using terephthalic acid as a raw material currently applied by the majority of polyester companies.

Therefore, the technical problem to be achieved in the present invention is to produce a copolyester by depolymerization by the glycolysis method that can be regenerated in the existing polyethylene terephthalate polymerization equipment and copolymerization by the addition of aromatic diol.

The present invention for solving the above problems will be described in detail.

1. Selection of regeneration target

 The object of polyethylene terephthalate regeneration aimed at in the present invention is for all products such as fibers, films and bottles. The target product may be crushed through a process such as washing and drying in order to remove foreign matters and then introduced into the reactor.

Foreign substances adhering to the product by processes such as cleaning and drying, for example, emulsions or dyes in textiles, foreign substances such as PVC labels in bottles, and metals or paints coated on the surface in metal lids, etc. It is good to crush mainly.

2. Depolymerization reaction

In the depolymerization reaction, the polyethylene terephthalate compressed crushed product to be regenerated is introduced into a reactor equipped with a reflux tower, and then heated and melted. The reaction is carried out by adding a catalyst and glycol. For the purpose of copolyester, the glycol used ethylene glycol.

The amount of ethylene glycol added is preferably 1 to 5 times the number of moles of the repeating unit of polyethylene terephthalate. If the amount of ethylene glycol is less than 1 time, it is not sufficient depolymerization, so it is disadvantageous for copolymerization. If the amount of ethylene glycol is less than 5 times, the reaction becomes faster but the production of by-product diethylene glycol (DEG) is too much. And the burden of manufacturing costs will increase.

As the depolymerization catalyst, acetates of antimony, zinc, lead, cerium, manganese, cobalt, magnesium, calcium, potassium, sodium, lithium, aluminum, tin, cadmium and barium are mainly used. The input amount is preferably 100 to 5000 ppm of the weight of polyethylene terephthalate added to the reaction based on the metal content. If less than 100ppm is added, the depolymerization rate is too slow to delay the reaction. If it is more than 5000ppm, the rate of depolymerization is too fast to control the process, and it is difficult to control the process. Not only that, but also deterioration of heat resistance may be caused.

After completion of the depolymerization reaction, the activity of the depolymerization reaction catalyst should be reduced by using a phosphorus compound. The amount of the phosphorus-based compound may be added in an amount of 1 to 2 molar times based on the phosphorus atom based on the metal of the depolymerization reaction catalyst. If it is lower than 1 mole times, it is difficult to lower the activity of the catalyst. If it is more than 2 mole times, the polycondensation rate of the copolyester may be lowered.

As the phosphorus compound, phosphate compounds such as phosphoric acid, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, phosphite compounds such as trimethyl phosphite, and phosphine compounds such as triphenyl phosphine are suitable.

Depolymerization reaction temperature is suitable 260 ~ 300 ℃. When the reaction temperature is lower than 260 ° C., the polyethylene terephthalate does not melt well and the reaction is too slow. When the reaction temperature is higher than 300 ° C., the thermal degradation of the polyethylene terephthalate itself is likely to occur.

3. Input of Copolymerization Monomer

After the depolymerization reaction is completed, the addition of the copolymerization monomer may vary depending on the aspect of the copolymerization monomer.

If melting point like Isophthalic acid is higher than 300 ℃ or it is insoluble, it should be mixed with ethylene glycol and added as slurry. If melting point is lower than depolymerization temperature like dimethyl isophthalate, etc. It may be melted and introduced into the liquid phase.

As the compound represented by the formula (1), various materials can be used according to the properties of the required copolymer, and particularly industrially useful materials are isophthalic acid, naphthalene dicarboxylic acid, anthracene dicarboxylic acid, fluorene dica Lenic acid, these alkyl ester compounds, etc. are mentioned.

ROOC-A-COOR ------------------------------- Formula (1)

(Wherein A represents an aromatic group containing an aromatic group such as benzene, naphthalene, anthracene, or a metal salt thereof, and R represents hydrogen or an alkyl group.)

4. Input of inorganic additive

 Inorganic additives may be added depending on the use of the copolymer to be produced. Inorganic additives such as titanium dioxide, silica, barium sulfate, magnesium acetate, cobalt acetate and the like can be added within a range that does not significantly impair the physical properties of the copolymer.

Hereinafter, the present invention will be described in detail. However, the present invention is not limited by the examples. Terms and assays to be used in the examples and the like are described below.

1. Intrinsic viscosity: The polymer was dissolved in a solution containing phenol and 1,1,2,2-tetrachloroethane in a 60/40 weight ratio, and measured using a Ubbelode tube in a 30 ° C thermostat.

2. Melting point: The melting point was determined by the peak of the melting peak by analyzing the prepared copolyester by DSC-7 of Perkin Elmer.

<Examples 1-5, Comparative Examples 1-6>

100 kg of the raw material obtained by separating, washing, drying and crushing the polyethylene terephthalate bottle was introduced into a reactor equipped with a reflux tower and melted at the temperatures shown in Table 1. After melting, the catalyst was dissolved in ethylene glycol as the catalyst and the amounts described in Table 1, and the reaction was carried out by introducing into the reactor. During the reaction, depolymerization was carried out by refluxing to prevent the outflow of ethylene glycol. The depolymerization was terminated when the depolymerization progressed and the internal solution viscosity became 1000 centipoise or less. 12 kg of isophthalic acid was added to 5.5 kg of ethylene glycol as a copolymerized monomer to prepare a slurry. The reaction was terminated by adding the phosphorus compounds shown in Table 1 when the reaction rate was 95% or more. The prepared reactant was transferred to a polycondensation reactor, and 300 ppm of antimony trioxide was added to the polymer as a polycondensation catalyst, and the reaction was performed for 2.5 hours under a vacuum of 0.5torr or less. Physical properties of the prepared polymer are shown in Table 1.

[Table 1] Reaction Conditions and Physical Properties

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Melting temperature
(℃) 270 270 280 280 280 270 270 230 310 270 270 Catalyst type ^{* 1} Zn Zn Co Co Mn Zn Zn Zn Co Mn NaOH Catalyst input ^{* 2} 2000 2000 1500 3000 1000 2000 2000 2000 2000 10000 1000 EG injection amount ^{* 3} 64 97 97 97 97 26 193 97 97 97 97 Phosphorus Compound Type ^{* 4} Phosphoric Acid Phosphoric Acid Phosphoric Acid TMP TPP Phosphoric Acid Phosphoric Acid Phosphoric Acid Phosphoric Acid Phosphoric Acid Phosphoric Acid Phosphorus Compound Input ^{* 5} 1050 1050 800 2000 800 1050 1050 1050 1050 1050 2500 Intrinsic viscosity (IV) 0.65 0.64 0.64 0.64 0.63 0.62 0.64 0.61 0.58 0.58 0.42 DEG content 1.7 2.0 1.9 2.0 2.1 1.4 4.6 5.1 2.4 2.9 1.2 Col-b 2.1 2.2 1.5 1.3 1.9 5.9 7.2 4.6 6.9 7.1 4.1

* 1 Zn: Zinc acetate dihydrate (Zn (OCOCH ₃ ) ₂ ㆍ 2H ₂ O)

Co: Cobalt acetate tetraacetata (Co (OCOCH ₃ ) ₂ ㆍ 4H ₂ O)

Mn: Manganese acetate tetraacetate (Mn (OCOCH ₃ ) ₂ ㆍ 4H ₂ O)

*2. Catalyst input: Catalyst input (ppm) for raw material PET (100kg)

* 3. EG input is the amount excluding catalyst (Kg)

*4. TMP: Trimethyl Phosphate, TPP: Triphenyl phosphate

* 5. Phosphorus Compound Input: Input to Raw Material PET (ppm)

<Example 6>

Titanium dioxide (TiO 2) dispersed in ethylene glycol at a concentration of 20 wt% was carried out in the same manner as in Example 1 except that 0.3 wt% of TiO 2 was added to the polymer. A polymer with an intrinsic viscosity of 0.64 dl / g was obtained and dried in a vacuum dryer, followed by a spinning temperature of 290 ° C., a first high roller temperature of 80 ° C., a speed of 1400 m / min, a second high roller temperature of 115 ° C., and a speed of 4000 m / min. Spinning produced polyester fibers of 30 denier / 12 filaments. The non-shrinkage rate was 21%.

<Example 7>

The same procedure as in Example 1 was carried out except that 15 kg of a 35% by weight ethylene glycol solution of dihydroxyethylisophthalate sodium salt represented by the formula (2) was added instead of the isophthalic acid slurry. A polymer having an intrinsic viscosity of 0.54 dl / g was obtained and dried in a vacuum dryer to produce a spinning temperature of 300 ° C., a first high roller temperature of 82 ° C., a speed of 1300 m / min, a second high roller temperature of 125 ° C., and a speed of 3800 m / min. Spinning to produce a polyester fiber of 40 denier / 24 filaments. The prepared fibers were dyed with Kayakryl Dye (Cathion Dye) of Nippon Chemical Co., Ltd. to confirm that they exhibit the same dyeing properties as general Cationic Dye Salted Polyester fibers.

-----------식 (2)

----------- Equation (2)

<Example 8>

It carried out similarly to Example 1 except having injected 30 kg of 2, 6- dimethyl naphthalene dicarboxylate melted at 100 degreeC instead of the isophthalic acid slurry. A polymer having an intrinsic viscosity of 0.63 dl / g was obtained and dried in a vacuum dryer and extruded at an extrusion temperature of 280 ° C. to prepare a sheet having a thickness of 3 mm. The transparency was 98% level, Haze confirmed the physical properties of less than 1.

Regeneration of the polyethylene terephthalate according to the present invention can reduce environmental pollution as well as the copolyester resin prepared using the same can be applied to various applications such as fibers, bottles, films.

Claims (7)

After the polyethylene terephthalate product was added to the reactor, the mixture was heated and melted and depolymerized by the glycolysis method of adding a catalyst and ethylene glycol, and a phosphorus-based compound was added to reduce the activity of the depolymerization reaction catalyst. A method for producing a regenerated copolyester resin, which is prepared by adding an aromatic dieside or an ester forming derivative thereof. ROOC-A-COOR ------------------------------- Formula (1) (Wherein A represents an aromatic group containing benzene, naphthalene and anthracene, or an aromatic group containing a metal salt thereof, and R represents hydrogen or an alkyl group.) The method for producing a recycled copolyester resin according to claim 1, wherein the amount of ethylene glycol added is 1 to 5 times the number of moles of the repeating unit of polyethylene terephthalate. The compound according to claim 1, wherein the compound used as the depolymerization catalyst is antimony, zinc, lead, cerium, manganese, cobalt, magnesium, calcium, potassium, sodium, lithium, aluminum, tin, cadmium, barium. Method for producing a regenerated copolyester resin, characterized in that selected from the acetate. The method of claim 1 or 2, wherein the amount of depolymerization catalyst used is 100 to 5000 ppm of the weight of polyethylene terephthalate added to the reaction on the basis of the metal content. Way. The method for producing a recycled copolyester resin according to any one of claims 1 to 3, wherein the phosphorus compound used is selected from a phosphate compound, a phosphite compound, and a phosphine compound. The regenerated copoly according to any one of claims 1 to 3, wherein the amount of phosphorus-based compound added is 1 to 2 mole times based on the phosphorus atom based on the metal of the depolymerization reaction catalyst. Method for producing ester resin. The regenerated copolyester resin according to any one of claims 1 to 3, prepared by the method.