JP2002167431A - Polyethylene terephthalate resin composition and its discrimination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyethylene terephthalate resin composition whose discrimination can be easily carried out from a polyethylene terephthalate resin comprising virgin terephthalic acid in the processing of the composition to a resin molded product and whose quality is equal to that of the resin comprising the virgin terephthalic acid and to provide a discrimination method for the composition. SOLUTION: A terephthalic acid which is composed of a carbon or/and hydrogen isotope as a discrimination compound is added in an amount of 1-1,000 weight ppm to all of terephthalic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene terephthalate resin composition comprising a terephthalic acid composition containing terephthalic acid composed of carbon and / or hydrogen isotopes as an identification compound, and a method for identifying the same. More specifically, polyethylene terephthalate is depolymerized and methanol-esterified terephthalic acid (hereinafter abbreviated as “raw material recycling TA”) is provided with dimethyl terephthalate composed of carbon and / or hydrogen isotopes as an identification compound. Dimethyl terephthalate produced from para-xylene (hereinafter abbreviated as virgin DMT) when the polyethylene terephthalate resin composition comprising the terephthalic acid composition obtained by the addition and hydrolysis is further processed into a resin molded product. And virgin Refutaru acid (hereinafter, virgin TA
And a polyethylene terephthalate resin composition having the same quality as the polyethylene terephthalate resin.

[0002]

2. Description of the Related Art At present, polyethylene terephthalate (hereinafter abbreviated as PET) is widely used in the world as fibers, resins, packaging materials, films, and other molded articles. Disposal has become a major issue in recent years. In recent years, used PE
After being collected, the T bottle undergoes a crushing process, a separation process from other materials, and a washing process, and a circulation loop of material recycling to be reprocessed into fibers, sheets, and the like is formed, and the T bottle has begun to function.

[0003]

However, the materials processed by this system are limited in terms of reprocessing equipment and conditions, and there is also a problem that the quality of reprocessed resin products deteriorates, and the applications thereof are also restricted. I have. Further, it has not been possible to easily distinguish a material recycled reworked resin product from a resin product made of a resin made of a virgin material.

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyethylene terephthalate resin composition which can easily identify that a recycled resin is used and which has a small difference in quality from a virgin resin product, and a method for identifying the same. It is an object of the present invention to provide a resin molded product such as a hollow molded product, a thermoformed container, a sheet, and an injection molded product.

[0005]

Means for Solving the Problems The present inventors have made intensive studies in view of the above prior art, and as a result, completed the present invention.

That is, an object of the present invention is to provide terephthalic acid composed of isotopes of carbon and / or hydrogen as a discriminating compound in an amount of 1 to 1000 wt.
It can be achieved by a polyethylene terephthalate resin composition to which pm is added.

Another object of the present invention is to provide a polyethylene terephthalate resin composition, wherein terephthalic acid composed of isotopes of carbon and / or hydrogen as an identification compound is used in an amount of 1 to 1000 with respect to all terephthalic acids.
It is achieved by a method for identifying a polyethylene terephthalate resin composition, characterized by using a terephthalic acid composition added by weight ppm.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

In the identification method of the present invention, first, an isotope compound of dimethyl terephthalate, which is an identification compound, is required. The isotope of carbon is ¹³ C, and the isotope of hydrogen is deuterium. Isotopic compounds of dimethyl are preferred. Among the isotopic compounds of the dimethyl terephthalate, terephthalic acid - carboxy - ¹³ C-dimethyl ester, terephthalic acid - carboxy - ¹³ C ₂ - dimethyl ester, terephthalic acid - ¹³ C ₆ - dimethyl ester, terephthalic acid -d- dimethyl Ester, terephthalic acid-d
It is preferably at least one isotope compound selected from the group consisting of ₄ -dimethyl esters.

Next, the polyester is subjected to a depolymerization reaction in EG in the presence of a known depolymerization catalyst. Here, the polyester is polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, or polyhexamethylene terephthalate. If necessary, the mixture obtained in the depolymerization reaction is extracted with excess EG used in the depolymerization reaction, then introduced into a reactor together with MeOH, and subjected to substitution esterification reaction and cooling crystallization to obtain crude terephthalic acid. Obtain dimethyl. Further, by distilling and purifying the obtained crude dimethyl terephthalate, high-purity dimethyl terephthalate can be obtained.

The high-purity recovered dimethyl terephthalate obtained through the above steps is kept in a molten state at 140 to 170 ° C., and the isotope compound of dimethyl terephthalate can be added by a known method. The continuous type can be adopted without any problem. For example, when the isotope compound is added, the form in which the isotope compound is in the form of a fine powder or a slurry state of an organic solvent represented by, for example, methanol is added, and after the addition, the dimethyl terephthalate is stirred or liquid-circulated. And a method of dispersing them uniformly. Subsequently, the terephthalic acid composition is obtained by hydrolyzing the obtained terephthalic acid composition.

The dimethyl terephthalate composed of carbon and / or hydrogen isotopes as the discriminating compound is contained in the dimethyl terephthalate recovered from the polyester using EG and MeOH in an amount of 1 to 1000 ppm by weight, preferably 50 to 1000 ppm by weight. It is preferable to add 300 ppm by weight.
If the addition amount is less than 1 ppm by weight, detection is difficult, and if it exceeds 1000 ppm, the quality and moldability of the resin composition are deteriorated, which is not preferable.

The polyethylene terephthalate resin composition of the present invention comprises a terephthalic acid composed of carbon and / or hydrogen isotopes as a discriminating compound in an amount of 1 to 1000 ppm by weight based on the total terephthalic acid. It is.

The polyethylene terephthalate of the present invention comprises:
It is a thermoplastic polyester composed of terephthalic acid units and ethylene glycol units, and it is preferable that the terephthalic acid units be 85 mol% or more of the total acid component and the ethylene glycol units be 85 mol% or more of the total diol component. . The terephthalic acid unit is preferably terephthalic acid.

The above-mentioned terephthalic acid is obtained by depolymerizing polyethylene terephthalate with ethylene glycol, and then further hydrolyzing dimethyl terephthalate obtained by transesterification with methanol. Alternatively, terephthalic acid to which terephthalic acid composed of carbon isotopes is added in an amount of 1 to 1000 ppm by weight is preferable.

In the range of less than 15 mol% of the total acid components, for example, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid,
1,7-naphthalenedicarboxylic acid, other isomers of naphthalenedicarboxylic acid, aromatic dicarboxylic acids such as isophthalic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyletherdicarboxylic acid, diphenylsulfonedicarboxylic acid, hexane, etc. Alicyclic dicarboxylic acids such as hydroterephthalic acid and hexahydroisophthalic acid, aliphatic dicarboxylic acids such as adipic acid, sebacic acid and azelaic acid, p-β-hydroxyethoxybenzoic acid and ε-oxycaproic acid; At least one or more acid components selected from bifunctional carboxylic acids such as oxyacids can be copolymerized.

In the range of less than 15 mol% of the total diol component, for example, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentyl glycol, diethylene glycol, etc. -1,1,1-cyclohexanedimethanol,
It can be at least one kind of diol such as 1,4-cyclohexanedimethanol, 2,2-bis (4′-β-hydroxyphenyl) propane, bis (4′-β-hydroxyethoxyphenyl) sulfone. .

In the present invention, a compound having three or more functional groups may be copolymerized with polyethylene terephthalate in a range of 2% or less.

Next, a method for identifying the polyethylene terephthalate resin composition of the present invention will be described.

The method for identifying a polyethylene terephthalate resin composition according to the present invention is characterized in that a raw material containing terephthalic acid and ethylene glycol to which terephthalic acid composed of isotopes of carbon and / or hydrogen is added as the above-mentioned identification compound is esterified. A bis (β-hydroxyethyl) terephthalate and / or an oligomer thereof is formed by a polymerization reaction, and then a melt polycondensation is performed at a high temperature under reduced pressure in the presence of a polycondensation catalyst and a stabilizer to obtain a polymer.

The esterification catalyst does not need to be particularly used because terephthalic acid serves as an autocatalyst for the esterification reaction. As the polycondensation catalyst, generally, a germanium compound, an antimony compound, a titanium compound, a cobalt compound, a tin compound and the like are known, but the polycondensation catalyst used in the present invention satisfies color tone, transparency, and hygiene. From the viewpoint, it is limited to germanium dioxide, and the addition amount is preferably 20 to 150 ppm (based on the acid component) of germanium element, more preferably 30 to 100 ppm, and further preferably 30 to 80 ppm. Examples of the stabilizer to be added at the time of polymerization include phosphoric esters such as trimethyl phosphate, triethyl phosphate and triphenyl phosphate, phosphites such as triphenyl phosphite and trisdodecyl phosphite, methyl acid phosphate and dibutyl phosphate. And phosphorus compounds such as monobutyl phosphate acidic phosphate, phosphoric acid, phosphorous acid, hypophosphorous acid, and polyphosphoric acid.

The above catalyst is used in a proportion of
The weight of the metal in the catalyst is generally in the range of 5 to 1000 ppm, preferably 10 to 500 ppm, and the ratio of the stabilizer used is generally 10 to 1000 ppm, preferably 10 to 1000 ppm, as the weight of phosphorus atoms in the stabilizer in all the polymerization raw materials. Is 20-5
The range is 00 ppm. The supply of catalyst and stabilizer
It can be carried out at any stage of the esterification reaction or transesterification reaction in addition to the preparation of the raw material slurry. Furthermore, it can be supplied at the beginning of the polycondensation reaction step.

The reaction temperature during the esterification or transesterification is usually from 240 to 280 ° C., and the reaction pressure is from normal pressure to 0.3 MPa. The reaction temperature during the polycondensation is usually 250 to 300 ° C., and the reaction pressure is usually 60
０．１0.1 Kpa. Such an esterification or transesterification reaction and a polycondensation reaction may be performed in one stage or may be performed in a plurality of stages. The polymer thus obtained has an intrinsic viscosity of usually 0.45 to 0.70 dl / g, and is formed into chips by an ordinary method. The average particle size of the polymer chip is usually 2.0 to 5.5 mm, preferably 2.2 to 5.5 mm.
The range is 4.0 mm. Next, the polymer obtained by melt polycondensation as described above is usually subjected to solid-state polymerization. The polymer chip to be subjected to the solid-phase polymerization is preliminarily heated to a temperature lower than the temperature at which the solid-phase polymerization is performed to perform pre-crystallization, and then subjected to the solid-phase polymerization. In the pre-crystallization step, the amorphous polymer chip is usually placed in a single-stage or in a fluid state at a temperature of usually 120 to 200 ° C., preferably 130 to 180 ° C. so as to prevent fusion due to chip crystallization heat generation. Treat in two steps for at least 15 minutes to crystallize.

The next solid phase polymerization step comprises at least one stage, usually at 190 to 230 ° C., preferably at 195 to 22 ° C.
The polymerization is carried out at a polymerization temperature of 5 ° C. under a vacuum of 0.05 to 5 Kpa, or under a normal pressure to 0.1 Mpa under a flow of an inert gas such as nitrogen, argon or carbon dioxide. The solid-state polymerization time may be shorter as the temperature is higher.
Time, preferably 5 to 30 hours, more preferably 10 to 30 hours.
25 hours. The intrinsic viscosity of the polymer obtained by the solid-state polymerization is usually 0.70 or more, and is in a range of 0.90 dl / g.

In the present invention, the content of diethylene glycol constituting the polyethylene terephthalate resin obtained by the above method is 0.7 to 2.0 wt% based on all diol units constituting the polyethylene terephthalate.
And preferably 1.0 to 1.5 wt%. If the amount is too small, the transparency of the bottle body after molding is deteriorated, and if it is too large, the heat resistance is reduced and the crystallization promoting effect is further reduced. As a method of adjusting the diethylene glycol content within the above range, in addition to using diethylene glycol as a polymerization raw material, diethylene glycol is partially produced as a by-product from ethylene glycol used as a main raw material. Can be adjusted. In addition, it is desirable to reduce as much as possible the oligomer component contained in the polymer that causes mold contamination during bottle molding, and the acetaldehyde component contained in the polymer that affects the taste and odor of the bottle filling, The oligomer content is 0.5 wt% or less, particularly preferably 0.4 wt% or less, and the acetaldehyde content is 5 ppm or less, particularly preferably 2 ppm or less.

Since oligomers and acetaldehyde are reduced during the above-mentioned solid-phase polymerization, the target levels can be reached by adjusting the IV, solid-phase polymerization time, and temperature time of the polymer after melt polymerization. . It is particularly preferable that the concentration of the terminal carboxyl group be in the range of 15 to 25 eq / ton. If the concentration of the terminal carboxyl group is less than the above range, it may take a long time to increase the intrinsic viscosity due to poor solid-state polymerizability, while if it exceeds the above range, solid-phase polymerization When used, the effect of reducing oligomers such as CT may be small.

The added isotope compound of terephthalic acid is
By performing analysis with ¹³ C NMR, ¹ H NMR, and gas chromatograph mass spectrometer, it is possible to determine and discriminate virgin from terephthalic acid.

The polyester resin composition produced by the method of the present invention can be molded into various molded articles.
For molding, a general molding method, for example, in the case of a hollow molded body,
Injection blow molding, orientation blow, extrusion blow, direct blow, injection blow, etc. are applied, and according to other molded articles, injection molding, sheet molding, inflation molding, thermoforming, various multilayer molding, etc. are applied. be able to.

First, the injection molding is carried out by melting the polyethylene terephthalate resin composition by heating it to a temperature not lower than its melting temperature, pouring the molten resin into a mold, and cooling and solidifying it. At this time, the mold is heated or cooled to a temperature appropriate for the polyethylene terephthalate resin composition. Further, the runner portion may be heated (hot runner) or not heated (cold runner) as necessary. The polyethylene terephthalate resin composition of the present invention has good moldability such as fluidity and crystallinity.

Second, the polyethylene terephthalate resin composition of the present invention can be formed into a bottle by employing a commonly used melt molding method. Specifically, for example, once molded parison by injection molding or extrusion molding,
As it is, or after processing the plug and bottom, reheat,
A stretch blow molding method such as a hot parison method or a cold parison method is applied. The molding temperature in this case (specifically, the temperature of each part of the cylinder of the molding machine and the nozzle) is 260
To 315 ° C, preferably 275 ° C to 295 ° C. The stretching temperature is equal to or higher than the glass transition temperature of polyethylene terephthalate and is usually 70 to 130 ° C. The stretching ratio is usually in the range of 1 to 4 times in the longitudinal direction and 1 to 5 times in the circumferential direction.

Although the obtained bottle can be used as it is, especially in the case of a content liquid which requires hot filling such as fruit juice drink, oolong tea, etc., it is generally heat-fixed in a heated blow mold and further heat-resistant. To be used. Heat setting is
Normally, the mold temperature is set to 100 to 200 under tension caused by compressed air or the like.
C. for several seconds to several minutes. Alternatively, a method is also employed in which a bottle larger than the final shape is formed, and the body is crystallized by being shrunk by heating, followed by blow molding in a mold having the final shape to obtain a product bottle.

Third, packaging materials of various shapes formed by thermoforming can be produced, for example, as follows. First, the polyethylene terephthalate resin composition is extruded with an extruder,
Take off in sheet form. Subsequently, the glass is heated to a temperature equal to or higher than the glass transition temperature, and compressed by air or vacuum to form, for example, a tray.
Etc., it is possible to obtain a good appearance and transparency.

[0033]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited by these examples. The characteristics in the examples were measured by the following methods. 1) Intrinsic viscosity (hereinafter abbreviated as IV): A sample cut out of a chip and a molded body was weighed in a predetermined amount, dissolved in o-chlorophenol to a concentration of 0.012 g / ml, and heated at 25 ° C.
Was measured. 2) Haze: A sample cut into a size of 50 mm × 50 mm from the body of the bottle was used for Colo manufactured by Nippon Denshoku Industries.
r and color difference met
er (MODEL1001DP). 3) Method for identifying terephthalic acid containing an identification compound: Terephthalic acid composed of isotopes of carbon and / or hydrogen in a resin composition is obtained by using an FT-NMR apparatus (JEOL A-600, manufactured by JEOL Ltd.). ) Was used to perform the analysis. 4) Acetaldehyde content (hereinafter abbreviated as AA): The AA content was measured by freeze-pulverizing a sample, charging the sample in a vial bottle, holding at 150 ° C. for 60 minutes, and using headspace gas chromatography manufactured by Hitachi. 5) Diethylene glycol content (hereinafter abbreviated as DEG): A sample was decomposed with hydrazine, and measured by gas colography. 6) Col-b: A fixed volume of the sample was quantified and measured with a color machine CM-7500 type color machine.

[0034] [Example 1] A polyethylene terephthalate depolymerized with ethylene glycol, followed by the dimethyl terephthalate obtained by transesterification with methanol, as identified compound, terephthalic acid - carboxy - ¹³
A terephthalic acid composition obtained by adding 50 ppm by weight of C ₂ -dimethyl ester and further hydrolyzing the resulting mixture is used to obtain a terephthalic acid composition (hereinafter abbreviated as “raw material recycled TA”) 40.
Of ethylene glycol and 22 parts of ethylene glycol to a polycondensation tank, and an esterification reaction was carried out at 275 ° C. for 4 hours under normal pressure. And an oligomer having a degree of polymerization of 5 to 10 was prepared. Thereafter, 0.017 parts of an ethylene glycol solution of phosphoric acid (phosphoric acid concentration: 5.5%) and an ethylene glycol solution of germanium dioxide (germanium dioxide concentration: 1%) After adding 0.38 parts, polycondensation was carried out under a reduced pressure of 2000 Pa for 1 hour, and subsequently at 277 ° C. for 2 hours under a reduced pressure of 133 Pa.

The produced polymer was drawn out in a strand form from a discharge port provided directly connected to a cooling water tank at the bottom of the polycondensation tank, cooled with water, and cut into chips to obtain polymer chips. Subsequently, the obtained polymer chips were crystallized with a stirring fluidized-type crystallizer, and then the solution was cooled to 1 under nitrogen flow.
After drying at 40 ° C. for 3 hours, the mixture was transferred to a packed column type solid-state polymerization tower, and subjected to solid-state polymerization at 215 ° C. for 22 hours under a nitrogen flow to produce a chip-like polyethylene terephthalate resin composition. The obtained polyethylene terephthalate resin composition had an intrinsic viscosity of 0.75, DEG of 1.3 wt%, and AA =
1.5 ppm, Col-b = -1.0.

The obtained polyethylene terephthalate
When ¹³ C NMR was used, the signal intensity of the carboxyl group carbon considered to be derived from terephthalic acid-carboxy- ¹³ C ₂ -dimethyl ester was detected to be abnormally high as compared with the signal intensity of the other carbons. The spectrum was different from that of polyethylene terephthalate.

After the chip was dried at 160 ° C. for 5 hours using a dryer, an injection molding machine (“M-100” manufactured by Meiki Seisakusho Co., Ltd.) was used.
DM ”), cylinder temperature 275 ° C., screw rotation speed 160 rpm, primary pressure time 3.0 seconds, mold temperature 10
℃, cycle 30 seconds, outer diameter about 28mm, inner diameter about 19m
m, a length of 136 mm and a weight of about 56 g were injection molded into a cylindrical preform. The intrinsic viscosity of the obtained preform was 0.69, the acetaldehyde content was 12 ppm, and the moldability and appearance were good. Subsequently, the preform was preheated to a surface temperature of about 110 ° C. by an infrared heater, stretch-blow-molded by a blow molding machine set at a blow pressure of 5 to 40 kg / cm ² and a mold temperature of 150 ° C., and the average wall thickness of the body was 330 μm. A bottle having an internal volume of about 1.5 liters was formed. The haze of the obtained bottle was 0.8%, and the moldability and appearance were good.

Reference Example 1 The same procedure as in Example 1 was carried out except that terephthalic acid was a virgin terephthalic acid (without discriminating compound) manufactured by Mitsui Chemicals, Inc. Intrinsic viscosity 0.75, Col
−b = −1.5, DEG = 1.3 wt%, AA = 1.3
ppm of a polyethylene terephthalate resin composition was obtained. The signal intensity of each carbon was almost the same as that of known polyethylene terephthalate.

First, the preform was molded in the same manner as in Example 1, and the intrinsic viscosity of the obtained preform was 0.6.
9. With an acetaldehyde content of 12 ppm, the moldability and appearance were good. Furthermore, blow molding was carried out in the same manner as in Example 1. The haze of the bottle was 1.0%, and the moldability and appearance were good.

[0040]

According to the present invention, polyethylene terephthalate is depolymerized, and dimethyl terephthalate esterified with methanol is added to carbon or / and / or as an identification compound.
And dimethyl terephthalate composed of isotopes of hydrogen and 1 to 1000 ppm by weight are added, and a terephthalic acid composition obtained by further hydrolyzing the dimethyl terephthalate is a resin molded product. Further, it is possible to provide a polyethylene terephthalate resin composition having the same quality as polyethylene terephthalate resin made of virgin TA, and a method for identifying the same.

Claims (5)

[Claims] 1. A polyethylene terephthalate resin composition comprising 1 to 1000 ppm by weight of terephthalic acid composed of carbon and / or hydrogen isotopes as a discriminating compound with respect to all terephthalic acids. 2. The polyethylene terephthalate resin composition according to claim 1, wherein the carbon isotope is ¹³ C. 3. The method according to claim 1, wherein the isotope of hydrogen is deuterium.
The polyethylene terephthalate resin composition according to the above. 4. A hydrogen or / and dimethyl terephthalate composed of isotopes of carbon, terephthalic acid - carboxy - ¹³ C-dimethyl ester, terephthalic acid - carboxy - ¹³ C ₂ - dimethyl ester, terephthalic acid - ¹³ C ₆
- Polyethylene terephthalate resin composition according to claim 1, wherein at least one isotope compound selected from the group consisting of dimethyl ester - dimethyl ester, terephthalic acid -d- dimethyl ester, terephthalic acid -d _4. 5. A terephthalic acid composition in which a terephthalic acid composed of carbon and / or hydrogen isotopes as a discriminating compound is added in an amount of 1 to 1000 ppm by weight based on all terephthalic acids in producing a polyethylene terephthalate resin composition. A method for identifying a polyethylene terephthalate resin composition, comprising using: