JPH0971639A - Production of modified polyester resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester resin capable of controlling only a crystallization velocity without deteriorating transparency when a forming or a preform as its precursor is treated by heat for imparting heat resistance. SOLUTION: A polyester resin is obtained by polymerizing a dicarboxylic acid component mainly consisting of terephthalic acid or its lower alkyl ester with a glycol component mainly consisting of ethylene glycol. Chips are formed from the obtained polyester resin, and the polyester resin chips are brought into contact with a polyethylene material under flowing.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polyester resin which is useful for bottles, films and sheets. More specifically, the present invention relates to a method for producing a polyester resin having a controlled crystallization rate without impairing transparency.

[0002]

2. Description of the Related Art Polyester (hereinafter referred to as PET)
Is excellent in mechanical strength, chemical stability, transparency, hygiene, gas barrier property, etc., and is lightweight and inexpensive, so it is widely used as a packaging material for various sheets and containers. Beverages, fruit juice drinks, liquid seasonings, edible oils,
The growth as a container for sake and wine is remarkable. In the case of PET, for example, in the case of a bottle, a preform for a hollow molded body is molded by an injection molding machine, and this preform is stretch-blown in a mold having a predetermined shape.

Further, in the case of a content liquid such as a fruit juice drink which requires hot filling, a method of crystallizing the mouth part of a preformed or molded bottle by heat treatment (Japanese Patent Laid-Open No. 55-79237). JP-A No. 58-110221, etc.) is generally used. The known method as described above, that is, the method of heat-treating the plug portion and the shoulder portion to improve the heat resistance is a crystallization time, the temperature greatly affects the productivity, and the treatment is performed at a low temperature in a short time. It is preferable to use a polyester raw material resin that has a high crystallization rate. On the other hand, the body is required to be transparent even when subjected to heat treatment during molding so that the color tone of the filling is not deteriorated, and the spout and the body need to have contradictory properties.

[0004]

However, in general,
Polyester resin with excellent transparency is slow to crystallize,
Improving the crystallization rate by lowering the intrinsic viscosity of the resin at the expense of transparency, or sacrificing the productivity, heat treatment at high temperature for a long time is the only way to satisfy both properties. It was difficult. It is an object of the present invention to provide a polyester resin in which only the crystallization rate is controlled without impairing transparency when heat-treating a molded product or a preform which is a precursor thereof by heat treatment. It is a thing.

[0005]

Means for Solving the Problems The inventors of the present invention have made extensive studies to solve the above problems, and as a result, by contacting a resin during the polyester production process or after the production with polyethylene under flowing conditions, The inventors have found that the crystallization rate can be improved continuously and without impairing transparency, and have completed the present invention. That is, the configuration of the present invention is
A polyester resin obtained by polymerizing a dicarboxylic acid component containing terephthalic acid or its lower alkyl ester as a main component and a glycol component containing ethylene glycol as a main component is made into chips, and the chips of the polyester resin are made into polyethylene under flowing conditions. It exists in the manufacturing method of the modified polyester resin characterized by making it contact with a member.

Hereinafter, the configuration of the present invention will be described in detail. In the present invention, PET means polyethylene in which the ratio of oxyethylene oxyterephthaloyl units (hereinafter referred to as ET units) consisting of terephthalic acid or its lower alkyl ester and ethylene glycol to all constituent repeating units is, for example, 80 mol% or more. Terephthalate means 20 mol% of other acid component and / or other glycol component constituting the constitutional repeating unit other than the ET unit.
It may be included in the following range. Phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 4,4′-diphenylsulfonedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-phenylenedioxydiacetic acid, and these Structural isomers,
Aliphatic dicarboxylic acids such as malonic acid, succinic acid, and adipic acid, and dicarboxylic acids such as esters of these dicarboxylic acids or their derivatives, p-hydroxybenzoic acid,
Examples thereof include p-hydroxybenzoic acid esters and oxyacids such as glycolic acid or derivatives thereof. In addition, glycol components other than ethylene glycol include 1, 2
-Propanediol, 1,3-propanediol, 1,
Aliphatic glycols such as 4-butanediol, pentamethylene glycol, hexamethylene glycol and neopentyl glycol, alicyclic glycols such as cyclohexanedimethanol, and aromatic dihydroxy compound derivatives such as bisphenol A and bisphenol S. Can be mentioned.

Of these, P is particularly preferably used
ET has a ratio of ET units of 96.0 to 99.0 mol%.
And the proportion of 1,4,7-trioxaheptamethylene terephthaloyl unit (hereinafter referred to as DT unit) is in the range of 1.0 to 4.0 mol%, and most Preferably, the ratio of ET units is 96.5-9
It is in the range of 8.5 mol% and the ratio of DT units is 1.5.
PET in the range of ˜3.5 mol%.

The PET used in the present invention usually contains a metal atom derived from the polycondensation catalyst added during its production. Examples of the metal atom include germanium, antimony, titanium, cobalt and the like. As the PET targeted by the present invention, PET containing germanium as the metal atom is particularly preferable from the viewpoint of transparency. The above-mentioned PET can be produced with high productivity by performing melt polymerization and subsequent solid-phase polymerization in accordance with a conventionally known method for PET.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An example of the method for producing PET of the present invention will be specifically described below. PET in the present invention is
It is produced by using terephthalic acid or its ester-forming derivative and ethylene glycol or its ester-forming derivative as main raw materials. As mentioned above, other dicarboxylic acid components and / or other glycol components are used as raw materials in combination. May be.

A raw material containing terephthalic acid or its ester-forming derivative as described above and ethylene glycol or its ester-forming derivative is subjected to an esterification reaction or a transesterification reaction in the presence of an esterification catalyst or a transesterification catalyst. A bis (β-hydroxyethyl) terephthalate and / or an oligomer thereof is formed, and then melt polycondensation is performed under reduced pressure at high temperature in the presence of a polycondensation catalyst and a stabilizer to produce a prepolymer. Since terephthalic acid is an autocatalyst for the esterification reaction, it is not necessary to use an esterification catalyst, but it is also possible to carry out it in the coexistence of a polycondensation catalyst described later,
Further, a small amount of inorganic acid or the like can be used. As the transesterification catalyst, alkali metal salts such as sodium and lithium, and alkaline earth metal salts such as magnesium and calcium, and metal compounds such as zinc and manganese are preferably used, but manganese compounds are particularly preferable from the viewpoint of transparency. .

As the polycondensation catalyst, a germanium compound,
Compounds that are soluble in the reaction system, such as antimony compounds, titanium compounds, cobalt compounds, and tin compounds, are used alone or in combination, and germanium dioxide is particularly preferable in terms of the effects of the present invention, color tone, and transparency. As stabilizers, phosphoric acid esters such as trimethyl phosphate, triethyl phosphate, triphenyl phosphate, phosphite esters such as triphenyl phosphite and trisdodecyl phosphate, methyl acid phosphate, dibutyl phosphate, monobutyl phosphate acidic phosphorus Acid esters and phosphorus compounds such as phosphoric acid, phosphorous acid, hypophosphorous acid and polyphosphoric acid are preferred. The proportion of these catalysts or stabilizers to be used is usually 5 as the weight of the metal in the catalyst in the case of using the catalyst in all the polymerization raw materials.
It is used in the range of ~ 2000 ppm, preferably 10-500 ppm. In the case of a stabilizer, the weight of phosphorus atoms in the stabilizer is usually 10 to 1000 ppm, preferably 20 to 200 ppm. These catalysts and stabilizers can be supplied at the time of preparing the raw material slurry, at any stage of the esterification reaction or the transesterification reaction, and also at the beginning of the polycondensation reaction step.

The prepolymer chips thus obtained have a diameter of 2.0 to 5.5 mm, further 2.2 to 4.0 m.
It is desirable to have an average particle size of m. Next, the prepolymer chips thus obtained by melt polymerization are subjected to solid-phase polymerization, if necessary. The prepolymer chip to be subjected to the solid phase polymerization may be heated to a temperature lower than the temperature at which the solid phase polymerization is performed in advance to perform pre-crystallization, and then supplied to the solid phase polymerization step. Such a pre-crystallization step is
Prepolymer chips are usually 120-200 in dry state
C., preferably 130 to 180.degree. C., for 1 minute to 4 hours by heating, or the chip is usually heated to 120.degree. C. under an atmosphere of steam or an inert gas containing steam.
It can also be carried out by heating to a temperature of up to 200 ° C. for 1 minute or more, and further, the prepolymer chips that have been hydrated and conditioned under water, water vapor or a water vapor-containing inert gas atmosphere,
It can also be carried out by heating to a temperature of 120 to 200 ° C. for 1 minute or more. The humidity of the prepolymer chips is adjusted so that the water content of the chips is usually in the range of 100 to 10000 ppm, preferably 1000 to 5000 ppm. By subjecting the prepolymer chip containing water to the crystallization step or the solid-state polymerization step, it is possible to further reduce the amounts of acetaldehyde contained in PET and impurities contained in a trace amount.

The solid-state polymerization process in which the above-mentioned prepolymer chips are supplied comprises at least one stage, and the polymerization temperature is usually 190 to 230 ° C., preferably 195 to 225.
℃, the pressure is usually 1kg / cm ² ~ 10mmHg,
Preferably, it is carried out under a condition of 0.5 kg / cm ^{2 to} 100 mmHg under a flow of an inert gas such as nitrogen, argon or carbon dioxide.

The higher the temperature, the shorter the solid phase polymerization time to reach the desired physical properties, but it is usually 1 to 50 hours, preferably 5 to 30 hours, and more preferably 10 to 25 hours. The present invention is characterized by improving the crystallinity of PET by bringing the polyester resin chipped by the above-mentioned operation into contact with polyethylene (hereinafter referred to as PE).

The type of PE used in the present invention is P of either low density polyethylene or high density polyethylene.
E may be used, or those obtained by lining these PEs may be used.

The improvement in the crystallization rate of PET by contacting with PE is usually exhibited in a contact time of an extremely short time of 0.01 to 1 second. Contact with PE requires that the PET resin is under flow conditions, which requires contacting the PET resin with PE. In the present invention, the PET resin chip is preferably brought into collision contact with the PE member in the space where the PE member is present. The space referred to here is, for example, a pipe for pneumatic transportation, a silo, or the like, and a PE member such as a rod-shaped or net-shaped molded body may be installed in the space so as to collide with and contact the tip of the PET resin. In the present invention, it is preferable to form part of the inner surface of the pneumatic transportation pipe with PE, and as a specific contact method, a part of the pneumatic transportation pipe or a part of the gravity drop pipe,
Part of the punching plate of the vibrating screen, the magnet portion of the magnet catcher, and the like may be made of PE or may be PE-lined, but not limited thereto. As described above, by bringing the PET resin after melt polycondensation into contact with PE, the crystallization speed can be improved without impairing the transparency.

[0017]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which, however, are not intended to limit the scope of the present invention. The various measuring methods used in the examples are as follows. (1) Intrinsic viscosity (hereinafter referred to as IV) It was measured at 30 ° C. in a mixed solvent of phenol / tetrachloroethane (weight ratio 1/1).

(2) Haze The temperature of each part of the cylinder and the nozzle head is set to 280 ° C.
Screw rotation speed 200 rpm, injection time 60 seconds, mold cooling water temperature 10 ° C., M-7 manufactured by Meiki Seisakusho Co., Ltd.
The haze meter N manufactured by Nippon Denshoku Co., Ltd. is used for the portions with thicknesses of 4 and 5 mm of the stepped molding plate obtained by the 0A injection molding machine.
The haze was measured using DH-300A.

(3) Crystallization temperature Differential scanning calorimeter DSC220C manufactured by Seiko Denshi KK
Was used as the sample, and a portion of the stepped molding plate having a thickness of 5 mm was used. The top temperature of the crystallization peak observed while heating from room temperature to 285 ° C. at a rate of 20 ° C./min was defined as the temperature rising crystallization temperature (T _C1 ). Continue to raise the temperature 2
After the temperature was maintained at 85 ° C for 3 minutes, the temperature was lowered at a rate of 10 ° C / min. The top temperature of the crystallization peak observed at this time was defined as the cold crystallization temperature (T _c2 ).

(4) Bottle transparency The temperature of each part of the cylinder and the nozzle head is set to 280 ° C.,
A preform is molded by an injection molding machine IS-60B manufactured by Toshiba Corp., in which the screw rotation speed is 100 rpm, the injection time is 10 seconds, and the mold cooling water temperature is 10 ° C., and then the preheating furnace temperature is 90 ° C. and the blow pressure is 20 kg. / Cm ² , and the molding cycle was set to 10 seconds by a stretch blow molding machine to form a bottle having an average meat pressure of the body of 300 µm and an internal volume of 1 liter, and the transparency was visually judged based on the following criteria. ◯: Good with no deformation or turbidity, Δ: Transparent but deformed,
×: Whitening during crystallization

Example 1 A slurry of 13.0 kg of terephthalic acid and 5.82 kg of ethylene glycol was prepared, and 0.30 was prepared in advance.
kg of bis (2-hydroxyethyl) terephthalate was added to an esterification tank kept at a temperature of 250 ° C.,
It was sequentially supplied over 4 hours. After the completion of the feeding, the esterification reaction was allowed to proceed for 1 hour, then half of the amount was transferred to a polycondensation tank, and 0.91 g of phosphoric acid (120 ppm of polymer) and 0.92 g of germanium dioxide (120 ppm of polymer) were charged, and from 250 ° C. While gradually raising the temperature to 278 ° C., the pressure was gradually reduced from normal pressure and maintained at 0.5 mmHg.
After the reaction was carried out for 3 hours, the produced polymer was withdrawn in a strand form from an outlet provided at the bottom of the polycondensation tank and cooled with water,
It was cut into chips. This polymer was made from PE by using a part of SUS-made aerodynamic transportation pipe (diameter 10 cm) over a length of 1 m.
Pipes made by Mitsubishi Chemical Corporation (low density polyethylene UE3)
It was transferred to the solid-state polymerization step using the pneumatic transportation pipe described in 20). When the polymer after transfer was analyzed, it was 4p.
PE of pb was detected.

The surface of the transferred polymer chips was crystallized at 150 ° C. with a stirring crystallizer (Bepex Co.), and then transferred to a stationary solid phase polymerization tower, under a nitrogen flow of 20 liter / kg / hour, After drying at about 140 ℃ for 3 hours, at 210 ℃ 2
Solid phase polymerization was carried out for 0 hours to obtain a solid phase polymerization chip. The obtained solid-state polymerized chip was injected into an injection molding machine (M-7 manufactured by Meiki Seisakusho KK).
Each stepped plate-shaped molded product was obtained by 0A). The physical properties of the obtained molded plate are shown in Table 1 below. In addition, an injection molding machine (manufactured by Toshiba Corp. IS-60
The preform was molded in B). The plug part of this preform is heated and crystallized by a self-made crystallization machine, and then blow-molded by a stretch blow molding machine to obtain a bottle having an average wall thickness of 300 μm and an internal volume of 1 l, and subsequently set at 150 ° C. The sample was heat-set in the above-described mold under compressed air tension for 10 seconds. Table 1 shows the physical properties of the obtained bottles.

COMPARATIVE EXAMPLE 1 SU was used without changing a part of the pneumatic transportation pipe to polyethylene pipe.
A chip was obtained by performing polycondensation reaction and solid phase polymerization under the same conditions as in Example 1 except that the S pipe was used as it was. Each stepped plate-shaped molded product was obtained from this chip by an injection molding machine in the same manner as in Example 1. Table 1 shows the physical properties of the obtained molded plate.
Further, using the obtained solid-state polymerization chip, a preform was molded in the same manner as in Example 1. Attempts were made to crystallize the plug part of this preform with a self-made crystallization machine, but deformation was observed at the end face of the plug part.

Example 2 After cooling the resin after the completion of solid phase polymerization, one of the magnet catchers in which five rod-shaped magnets (21 mm in diameter) can be set in one stage is treated with a device in which one stage is changed to a PE pipe. A chip was obtained under the same conditions as in Comparative Example 1 except for the above. When the obtained chip was analyzed, PE of 7 ppb was detected. Stepped plate-shaped molded products were obtained from the obtained chips in the same manner as in Example 1. Table 1 shows the physical properties of the obtained molded plate. Also, using the obtained solid-state polymerization chip,
A preform was molded in the same manner as in Example 1 to obtain a heat-fixed bottle in a 1-liter container.

[0025]

[Table 1]

[0026]

According to the present invention, it is possible to provide a polyester resin having a controlled crystallization rate without impairing transparency.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuya Nakamichi No. 1 Toho-cho, Yokkaichi-shi, Mie Prefecture Yokkaichi Research Institute, Mitsubishi Chemical Co., Ltd. (72) Inventor Osamu Kishiro No. 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Chemical Company Yokkaichi Research Institute

Claims (4)

[Claims] 1. A polyester resin obtained by polymerizing a dicarboxylic acid component containing terephthalic acid or a lower alkyl ester thereof as a main component and a glycol component containing ethylene glycol as a main component into chips, and the chips of the polyester resin are obtained. A method for producing a modified polyester resin, which comprises contacting with a polyethylene member under flowing conditions. 2. In the space where the polyethylene member is present,
The method of claim 1 wherein a tip of polyester resin is placed in impact contact with the polyethylene member. 3. The method according to claim 2, wherein the space is a pipe for pneumatic transportation. 4. The method according to claim 2, wherein the polyethylene member is a rod-shaped or net-shaped molded body.