JP3395423B2 - polyester - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to polyesters used for moldings such as bottles, films and sheets.
More specifically, the present invention relates to a polyester which is excellent in transparency when formed into a molded article and is inexpensive.

[0002]

2. Description of the Related Art Polyesters, especially polyethylene terephthalate (hereinafter referred to as "PET"), are excellent in mechanical strength, chemical stability, transparency, hygiene, gas barrier property, etc. As a container for beverages such as beverages, the growth has been remarkable in recent years. In the case of producing a polyester as a raw material for a hollow molded article such as such a container, a germanium compound, an antimony compound, a titanium compound or the like is generally used as a polymerization catalyst.

[0003] In particular, in Japan, the standards for transparency of hollow molded articles made of polyester are strict, so germanium catalysts are mainly used as polymerization catalysts because polyesters have low crystallinity and are easy to obtain molded articles with good appearance. Although used, the catalyst has the disadvantage of usually being expensive. On the other hand, overseas, an antimony catalyst, which is cheaper than a germanium catalyst, is mainly used, but the crystallization rate of polyester is faster than that when a germanium catalyst is used, and a hollow molded article with good transparency can be obtained. It has the drawback of being difficult.

To solve these problems, for example, there is known a method for producing a transparent and inexpensive polyester by limiting the ratio of the amount of an antimony compound used as a polymerization catalyst to the amount of a phosphorus compound used as a stabilizer ( JP-A-6-27
9579). However, even with a hollow molded article molded from the polyester obtained by such a method, it is difficult to obtain a molded article having sufficient transparency as compared with the case where a germanium catalyst is used alone.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyester which has excellent transparency when formed into a molded article and is inexpensive.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that the inorganic particles having a specific particle size in the produced polyester affect the transparency of the molded article, Further, they have found that the number of the inorganic particles can be controlled by using a specific ratio of antimony and germanium catalyst, and have reached the present invention.

That is, the gist of the present invention is to obtain a polyester having an antimony content of 30 to 250 ppm as an antimony compound and an antimony compound of 0.
A polyester produced by polycondensation using a germanium compound in an amount of 05 to 1.5 times as much as a catalyst,
Maximum length of 0.5 μm present in 0.1 g of the polyester
The present invention relates to a polyester characterized in that the number of inorganic particles is 10,000 or less.

The present invention will be described in detail below. The raw material of the polyester produced in the present invention is a dicarboxylic acid component mainly containing terephthalic acid or its ester-forming derivative which is a raw material used in known PET, and a diol component mainly containing ethylene glycol or its ester-forming derivative. To use. Further, a dicarboxylic acid component other than terephthalic acid and a diol component other than ethylene glycol may be contained usually up to about 20 mol% with respect to the total dicarboxylic acid component or the total diol component. It may also contain a small amount of a monofunctional compound or a trifunctional or higher-functional compound.

These dicarboxylic acids or their derivatives include phthalic acid, isophthalic acid, naphthalene dicarboxylic acid, 4,4'-diphenyl sulfone dicarboxylic acid, 4,
4'-biphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-phenylenedioxydiacetic acid,
And their structural isomers, aliphatic dicarboxylic acids such as malonic acid, succinic acid and adipic acid, and esters of these dicarboxylic acids, oxyacids or derivatives thereof include p-hydroxybenzoic acid and p-hydroxybenzoic acid ester. And glycolic acid.

The diol components are 1,2-propanediol, 1,3-propanediol and 1,4-propanediol.
Examples include aliphatic glycols such as 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. it can.

The polyester used in the present invention is ordinary PE.
It can be manufactured according to the manufacturing method of T. A raw material containing terephthalic acid or an ester-forming derivative thereof and ethylene glycol or an ester-forming derivative thereof is bis (β-hydroxyethyl) by an esterification reaction or a transesterification reaction in the presence of an esterification catalyst or a transesterification catalyst. A 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 (polymerization catalyst) to produce a polyester.

Since terephthalic acid serves as an autocatalyst for the esterification reaction, it is not necessary to use an esterification catalyst, but it can be carried out in the coexistence of a polycondensation catalyst described later, and a small amount of inorganic An 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. .

In the present invention, a germanium compound and an antimony compound are used together as a catalyst for polycondensation.
-250 ppm, preferably 50-200 ppm, more preferably 50-150 ppm of antimony compound and 0.05-
A 1.5-fold molar amount, preferably 0.07 to 1.0-fold molar amount of the germanium compound is used.

When the content of antimony is less than 30 ppm, it is necessary to increase the amount of the germanium compound used in combination to obtain a polyester having a predetermined intrinsic viscosity or molecular weight, which is disadvantageous in terms of cost. Also, antimony is 25
When it exceeds 0 ppm, the number of fine inorganic particles in the obtained polymer increases, the crystallization rate is extremely high, and the transparency of the obtained molded article from the polyester is deteriorated, which is not preferable. On the other hand, when the amount of germanium is less than 0.05 times the mole of antimony, the number of fine inorganic particles in the obtained polyester increases, so that the crystallization rate is extremely high and the transparency of the molded product from the obtained polyester deteriorates, which is preferable. Absent. Further, when the amount of germanium exceeds 1.5 times the mole of antimony, the amount of the germanium compound used in combination increases, which is disadvantageous in terms of cost and is not preferable. The amount of the germanium compound used is preferably selected so as to be 5 to 50 ppm as germanium with respect to the produced polyester.

Examples of the germanium compound used as the catalyst include germanium dioxide and germanium tetrachloride, with germanium dioxide being preferred. Examples of antimony compounds include antimony trioxide, antimony pentoxide, and antimony acetate.
Antimony trioxide is preferred. Such a catalyst is usually contained in the polycondensation reaction system in an amount of 0.1 to 10% by weight, preferably 0.5 to 5%.
It is desirable to add to the reaction system as an aqueous solution of about wt% or an ethylene glycol solution. A mixed solution of a germanium compound and an antimony compound may be added to such a solution, or may be added as separate solutions.

In the polyester of the present invention, a heat stabilizer may be added in the polymerization step. As the phosphorus compound, phosphoric acid esters such as trimethyl phosphate, triethyl phosphate, triphenyl phosphate and the like can be used. , Triphenyl phosphite, phosphite such as trisdodecyl phosphite, methyl acid phosphate, dibutyl phosphate, monobutyl phosphate acidic phosphate, and phosphoric acid,
Phosphorous compounds such as phosphorous acid, hypophosphorous acid and polyphosphoric acid can be mentioned, and phosphoric acid and phosphoric acid esters are particularly preferable. The addition amount of the phosphorus compound is usually 5 to 150 ppm, preferably 10 as a phosphorus atom with respect to the produced polyester.
~ 100 ppm is used.

Further, a cobalt compound may be used in combination for adjusting the color tone of the obtained polyester. The cobalt compound is preferably cobalt acetate, and is used as a metal in an amount of 5 to 100 ppm, preferably 5 to 60 ppm, based on the produced polyester. The above-mentioned method of supplying the catalyst and the stabilizer can be supplied at the time of preparing the raw material slurry or at any stage of the esterification reaction or the transesterification reaction, and further, can be supplied at the initial stage of the polycondensation reaction step.

In the present invention, the polyester obtained by polycondensation may be subjected to solid phase polymerization at a temperature below the melting point, if necessary. The solid phase polymerization step comprises at least one step and the polymerization temperature is usually 190 to 230 ° C., preferably 19
It is 5 to 235 ° C., and is carried out under an arbitrary pressure in a wide range of 15,000 to 1 Pa under a flow of an inert gas such as nitrogen, argon, carbon dioxide or the like, or under an atmosphere without flow. The higher the temperature, the shorter the polymerization time to reach the desired physical properties, but it is usually 1 to 30 hours, preferably 5
~ 25 hours. By appropriately selecting the above solid-phase polymerization conditions, a polyester having a desired intrinsic viscosity or molecular weight can be obtained.

The intrinsic viscosity of polyester is phenol /
3 in a mixed solvent of tetrachloroethane (weight ratio 1/1)
Measured at 0 ° C., usually adjusted to a range of 0.5 to 1.5 dl / g, and if less than 0.5 dl / g, it is difficult to obtain practical strength when the obtained polyester is used as a molded article,
When it exceeds 1.5 dl / g, the productivity as a polyester is low and the molding itself becomes difficult. Further, as the polyester for the hollow molded article by stretch blow molding, the intrinsic viscosity is particularly in the range of 0.6 to 0.9 dl / g,
It is preferable because molding is easy and a molded article having good transparency is easily obtained.

The polyester of the present invention produced by the above production method is characterized in that the amount of fine inorganic particles in the polyester is small and the molded product made of the polyester is excellent in transparency. Many of the fine inorganic particles in this case are derived from the catalyst component, and are usually fine particles that are difficult to be sufficiently removed by a filter or the like provided in the middle of piping in the manufacturing process, etc. Maximum length is 0.5-2
The particles have a size of about μm and a maximum length of up to about 10 μm. The number of inorganic particles having a maximum length of 0.5 μm or more present in 0.1 g of the polyester of the present invention is 20,000 or less, preferably 10,000 or less. Polyester 0.
When the number of inorganic particles of 0.5 μm or more in 1 g exceeds 20,000, the crystallization rate becomes extremely high, so that the whitening of the molded product is likely to occur and the transparency of the molded product is deteriorated, which is not preferable. As a standard of transparency, for example, the haze of a 5 mm-thick injection molded plate made of the polyester of the present invention is usually 4% or less, preferably 3% or less.

Further, in the polyester of the present invention,
The crystallization temperature defined below is usually 150 to 180 ° C.,
The temperature is preferably 160 to 175 ° C., and if the crystallization temperature is too high, the transparency of the molded article is lowered, which is not preferable.

The above polyester of the present invention can be molded into a hollow molded product, a film, a sheet or the like by using a generally used melt molding method. In producing the hollow molded body, for example, the parison molded from the polyester of the present invention can be stretch blow molded. Specifically, for example, a parison is once molded by injection molding or extrusion molding, and as it is, or after processing the plug portion and the bottom portion, it is reheated, and stretch blow molding such as hot parison method or cold parison method. The law applies. The molding temperature in this case, specifically, the temperature of each cylinder and nozzle of the tester is usually 260 to 300 ° C.
is there. The stretching temperature is usually 70 to 120 ° C., and the stretching ratio is usually 1.5 to 3.5 times in the machine direction and 2 to 2 in the circumferential direction.
It may be performed in a range of 5 times. The obtained hollow molded article can be used as it is, but in the case of a content liquid that requires heat filling, such as a fruit juice drink and oolong tea, it is generally further heat-set in a blow mold to further improve heat resistance. Used by giving. Heat fixation is usually performed under tension due to compressed air, etc.
It is carried out at 0 to 200 ° C. for several seconds to several minutes.

[0023]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Various measuring methods used in this example are shown below.

(1) Isophthalic acid unit amount in polyester (hereinafter referred to as "IPA amount") A sample was decomposed with methanol, and the produced dimethyl ester component was quantified by gas chromatography. (2) Germanium atom content (hereinafter referred to as "Ge amount") A sample was decomposed and ashed in the presence of sulfuric acid and quantified with distilled water to a certain amount, and quantified by an emission spectroscopic analysis method.

(3) Antimony atom content (hereinafter referred to as "Sb
The amount was determined by the same method as the analysis method of Ge amount. (4) Phosphorus atom content (hereinafter referred to as "P content") Quantified by the same method as the analysis method of Ge content. (5) Intrinsic viscosity (hereinafter referred to as “IV”) It was measured at 30 ° C. in a mixed solvent of phenol / tetrachloroethane (weight ratio 1/1).

(6) Number of Particles The number of inorganic particles in polyester can be measured by Pacific.
Automatic particle counter manufactured by Scientific Co., Ltd. (Brand name: Hiac / Leuco, Model: PC-32
0). 200 ml of a mixed solvent of phenol / tetrachloroethane (weight ratio: 2/3)
After melting at 125 ° C. for 1 hour, the number of all inorganic particles having a major axis of 0.5 μm or more was counted.

(7) Haze The 5 mm thick portion of the stepped shaped plate was measured for haze using a haze meter NDH-300A manufactured by Nippon Denshoku Co., Ltd.

[0028] (8) the crystallization temperature (hereinafter referred to as "T _C2") Seiko Instruments Co., Ltd. differential scanning calorimeter DSC220C
Was used as the sample, and a portion of the stepped molding plate having a thickness of 5 mm was used. The temperature was raised from room temperature to 285 ° C. at a rate of 20 ° C./min, held at 285 ° C. for 3 minutes, and then lowered at a rate of 10 ° C./min. The temperature was set to T _C2 .

(9) The temperature of each part of the transparent cylinder of the hollow molded body (bottle) and the nozzle head is 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. Molding was performed by a stretch blow molding machine set to 10 cm / cm2 and a molding cycle of 10 seconds to obtain a bottle having an average body wall thickness of 300 μm and an internal volume of 1.5 liter, and the transparency was visually judged.

Example 1 12700 parts terephthalic acid and 5 ethylene glycols
A raw material slurry consisting of 820 parts was prepared, 300 parts of bis (β-hydroxyethyl) terephthalate was added in advance, and the above raw material slurry was sequentially supplied to the esterification reaction tank at a temperature of 250 ° C. over 250 minutes. did. After the supply was completed, the esterification reaction was allowed to proceed for 60 minutes, and then half of the esterification reaction tank was transferred to the polycondensation reaction tank.
2.25 parts of phosphoric acid, 1.00 parts of antimony trioxide, and 1.40 parts of germanium dioxide were added, and the temperature was gradually raised from 250 ° C. to 280 ° C., and the pressure was gradually reduced from normal pressure and kept at 0.5 mmHg. . After the reaction in the polycondensation reaction tank was carried out for 3 hours, the produced prepolymer was extracted in a strand form from an extraction port provided at the bottom of the polycondensation reaction tank, water-cooled and cut into chips to obtain prepolymer chips. .

Further, with respect to half of the prepolymer chips, the surface thereof was stirred with a stirring crystallization machine (Bepex company type) for 150 times.
After crystallization at ℃, it was transferred to a stationary solid-phase polymerization tower, dried at about 150 ℃ for 3 hours under a nitrogen flow of 20 liters / kg / h, and then solid-phase polymerized at 210 ℃ for 20 hours. Got a chip. Table 1 shows the results of measuring the physical properties of the solid-state polymerization chip. Is IV 0.80 dl / g, Sb amount 50
ppm, Ge amount 29 ppm, P amount 42 ppm, number of inorganic particles having a major axis of 0.5 μm or more in polymer 0.1 g 1100
It was an individual.

Next, using the solid-state polymerization chip, the temperature of each part of the cylinder and the nozzle head was set to 280 ° C., the screw rotation speed was 200 rpm, the injection time was 60 seconds, and the mold cooling water temperature was 10 ° C. Injection molding machine M-7
A step forming plate was formed at 0A. The molded plate weighs about 50
g, a haze of a portion having a thickness of 5 mm of 0.7%, T _C2 165.
It was 4 ° C. Moreover, the obtained bottle was excellent in transparency.

Example 2 Example 1 except 1.48 parts phosphoric acid, 2.10 parts antimony trioxide and 1.50 parts germanium dioxide.
It carried out similarly to. Table 1 shows the measurement results. The obtained bottle was excellent in transparency.

Example 3 Example 3 was repeated except that 3.39 parts of diethylphosphoric acid was used in place of phosphoric acid, and 2.39 parts of antimony trioxide and 1.03 parts of germanium dioxide were used.
Table 1 shows the measurement results. The obtained bottle was excellent in transparency.

Example 4 Example 1 except that 2.20 parts phosphoric acid, 3.00 parts antimony trioxide and 0.85 parts germanium dioxide are used.
It carried out similarly to. Table 1 shows the measurement results. The obtained bottle was excellent in transparency.

Example 5 A step of preparing a raw material slurry consisting of 12500 parts of terephthalic acid, 263 parts of isophthalic acid, 5820 parts of ethylene glycol and 2.40 parts of phosphoric acid, and 4.00 parts of antimony trioxide and dioxide in a polycondensation reaction tank. The procedure of Example 1 was repeated, except that 0.70 parts of germanium and 1.27 parts of cobalt acetate tetrahydrate were added. Table 1 shows the measurement results. The obtained bottle was excellent in transparency.

Comparative Example 1 Example 1 except that 2.27 parts of phosphoric acid and 2.13 parts of germanium dioxide were used and no antimony trioxide was added.
It carried out similarly to. Table 1 shows each measurement result. The obtained bottle was excellent in transparency.

Comparative Example 2 Example 1 was repeated except that 1.60 parts of phosphoric acid and 3.00 parts of antimony trioxide were used and germanium dioxide was not added.
It carried out similarly to. Table 1 shows the measurement results. The obtained bottle was dull and was not excellent in transparency.

Comparative Example 3 Example 1 except that 4.80 parts of phosphoric acid and 4.80 parts of antimony trioxide were used and germanium dioxide was not added.
It carried out similarly to. Table 1 shows the measurement results. The obtained bottle was dull and was not excellent in transparency.

Comparative Example 4 Example 1 except that 2.37 parts of phosphoric acid, 4.80 parts of antimony trioxide and 0.23 parts of germanium dioxide are used.
It carried out similarly to. Table 1 shows the measurement results. The obtained bottle was dull and was not excellent in transparency.

As is clear from the results shown in Table 1, when germanium and antimony were used in combination, intermediate quality was expected from the results of germanium alone or antimony alone, but in the examples. However, it was unexpected that the average value was above the average of both, and was close to that of germanium alone. Further, the number of inorganic particles in the polyester is also small, and by setting the molar ratio Ge / Sb to the specific ratio of the present invention, the interaction between germanium and antimony is increased. Is estimated to be good.

[0042]

[Table 1]

[0043]

Industrial Applicability According to the polyester of the present invention, it is possible to obtain a molded article having a transparency equal to or higher than that of the polyester using germanium alone as a catalyst. Also,
Since the polyester of the present invention usually has a lower catalyst cost than the case where germanium is used alone as a catalyst, it is inexpensive and highly versatile.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Kishiro 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Chemical Corporation Yokkaichi Research Institute (56) References JP-A-61-85435 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 63/00-63/91

Claims (7)

(57) [Claims] 1. A polyester produced by polycondensation of an antimony compound of 30 to 250 ppm as an antimony and a germanium compound of 0.05 to 1.5 times the molar amount of an antimony compound with respect to the produced polyester as a catalyst. Te, polyester, wherein the maximum length 0.5μm or more of the number of the inorganic particles present in the polyester 0.1g of 10,000 or less. 2. The polyester according to claim 1, which is obtained by polycondensing 5 to 50 ppm of germanium compound as a catalyst with respect to the produced polyester. 3. The polyester according to claim 1, wherein the antimony compound and the germanium compound are added to the polycondensation reaction system as a 0.1 to 10% by weight aqueous solution or an ethylene glycol solution. 4. The polyester according to claim 1, which has an intrinsic viscosity of 0.6 to 0.9 dl / g. 5. The crystallization temperature is 160 to 175 ° C.
The polyester according to any one of claims 1 to 4, characterized in that
Le. 6. A hollow molded body made of a polyester according to any one of claims 1 to 5. 7. The hollow molded article according to claim 6 , which is obtained by injection-molding or extrusion-molding polyester to mold a parison, and stretch-blooming the parison.