JP3193191B2 - Polyester for bottle molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester for forming a bottle, and more particularly, to a polyethylene naphthalenedicarboxylate (hereinafter referred to as polyethylene naphthalate or PEN) having a good hue and excellent heat resistance and transparency. ).

[0002]

2. Description of the Related Art Polyester, especially polyethylene terephthalate (hereinafter sometimes abbreviated as PET) is widely used for fibers, films, industrial resins, bottles, cups, trays, etc. due to its excellent mechanical properties and chemical properties. ing.

[0003] In recent years, however, requirements for quality in various applications have become more severe. Among them, polyester containers, in particular, biaxially stretched blow containers, from the viewpoint of sterilization and preservation of the filling, further improvement in heat resistance and gas barrier properties are desired, and containers made of polyethylene terephthalate are considered to be insufficient. There is. In addition, a container having a good hue is required in terms of the appearance of the container, as well as heat resistance and gas barrier properties.

On the other hand, polyethylene naphthalate has also been known for its excellent characteristics, and is considered to be a material superior to PET in terms of heat resistance and gas barrier properties. Therefore, application to films and containers has been reported.

For example, Japanese Patent Application Laid-Open No. 52-45466 discloses a method in which a hollow container having excellent gas barrier properties, heat resistance, and transparency is used. PEN and PET to supplement etc.
And Japanese Patent Application Laid-Open Nos. 50-122549, 2-274575 and 2-27685.
No. 5 proposes this.

Further, a method for producing polyester using a salt of an alkali metal and / or alkaline earth metal as a catalyst is also common in terms of improving hue, preventing scale, and the like, and is disclosed in US Pat. No. 3,391,122. Kimi 48-3219
No. 5, JP-B-49-13234 and JP-B-2
No. 8616, for example. In particular, Tokuhei 2-
No. 8616 discloses an example of a method for producing a cloudless polyester which is suitable for hollow containers.

Therefore, PEN using these metal salts
When manufactured, it is inherently better in heat resistance and gas barrier properties than PET, so it can improve hue and transparency, and PEN is ideal for hollow containers where the required quality is strict. Is considered to be a polymer.

However, when a biaxially stretched blow container is actually formed, whitening occurs due to crystallization, or the surface of a bottle container formed with oligomer components adhered to a blow mold during blow stretching is roughened, resulting in transparency. There is a problem that it decreases.

Therefore, as a result of various studies on these problems, PEN was carried out by a direct polymerization method without using a transesterification catalyst such as an alkali metal or an alkaline earth metal.
By producing a polymer, it is possible to suppress whitening due to crystallization during stretching, which is considered to be due to the effect of catalyst particles remaining in the polymer, and further to improve the thermal stability, thereby improving the hue of the polymer. Moreover, by using a Ge compound as a polymerization catalyst, it is possible to suppress the generation of oligomers without deteriorating its hue,
In addition, by removing a part of the generated oligomer, the amount of the oligomer attached to the mold is suppressed, and as a result, a molded bottle free from fogging is obtained. These effects are overlapped, and the present invention has been found to be a material capable of obtaining a molded bottle having good hue overall, not causing whitening due to crystallization, and free from fogging.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polyester material for forming a bottle which is excellent in hue, free of whitening and fogging at the time of forming a bottle, and has excellent transparency and heat resistance.

[0011]

The present invention relates to naphthalene-2,6-dical.
Dicarboxylic acid mainly composed of boric acid and ethylene glycol
Esterify the main glycol with
Polycondensation using a platinum compound as a catalyst.
Reduce the amount of oligomers contained before
Inherent viscosity less than 0.5
The method for producing a bottle-forming polyester having a size of less than 1.0
You .

The "dicarboxylic acid component" used in the present invention mainly includes naphthalene-2,6-dicarboxylic acid, but other dicarboxylic acids (for example, naphthalene-dicarboxylic acid) in a range of 5 mol% or less of the total acid component. (2,7-dicarboxylic acid, terephthalic acid, isophthalic acid, etc.).

As the "glycol component" used in the present invention, ethylene glycol is mainly used, but other glycols (for example, diethylene glycol, neopentyl glycol, hexamethylene glycol, etc.) in an amount of 5 mol% or less of the total glycol component. ) Can be used.

On the other hand, as the “germanium compound”,
Germanium oxide, germanium hydroxide, germanium alcoholate, germanium halide, and other germanium compounds known to have catalytic activity can all be used, but germanium oxide is more preferable.

The germanium compound is preferably added after the completion of the esterification reaction. The amount of the germanium compound used is 10 to 50 mmol% (mmol) based on the dicarboxylic acid component.
%). If the amount of the catalyst is less than 10 mmol%, the function as a polymerization catalyst is insufficient, so that a polymer having a sufficiently high [η] cannot be obtained and cannot be used as a bottle molding polymer. If the amount of the catalyst exceeds 50 mmol%, the amount of the germanium compound remaining in the polymer is too large.
It cannot be used as a bottle molding material for food hygiene.

In addition, it is preferable to use a phosphorus compound (for example, phosphoric acid, phosphorous acid and their alkyl esters or aryl esters) during the polycondensation reaction.

The polymer obtained by a conventional polyester melt polymerization process has an oligomer content of 0.4 wt%.
Performed by a conventional method solid phase polymerization under vacuum or under a stream of N ₂ to less final intrinsic viscosity 0. The range is 5 to 1.0.

In the present specification, the "oligomer contained" refers to a chain or cyclic low-molecular compound in which naphthalene glycol units are dimerized to pentamer, and the total amount is defined as the amount of oligomer.

In the present invention, the polycondensation catalyst is limited to a germanium compound. However, even if the amount of oligomer contained once by solid phase polymerization is suppressed to 0.4 wt% or less, as a polymerization catalyst other than a germanium compound, for example, an Sb compound , T
When the i-compound is used, if the preform of the bottle is obtained by injection molding, the amount of the oligomer increases again at the time of melting at that time. Therefore, the germanium compound is suitable for suppressing the amount of the oligomer.

[0020]

According to the present invention, the polyester material obtained in the present invention has a good hue and can maintain its excellent transparency even after bottle molding, and can be advantageously used as a bottle molding material.

[0021]

The present invention will be described in detail with reference to the following examples. In the examples, “parts” means parts by weight.

Intrinsic viscosity [η] phenol / tetrachloroethane (60/40 weight ratio)
It calculates from the solution viscosity measured at 35 degreeC using the mixed solvent.

Colb CM-1500 color machine manufactured by Color Machine Co.
Measure lb.

Oligomer content Liquid chromatographic system (LC-6A manufactured by Shimadzu Corporation)
Quantification is performed using the system.

Bottle Transparency Evaluation The obtained polymer pellets were used to obtain a preform for bottle molding with a molding machine M-100A manufactured by Meiki Seisakusho Co., Ltd., and further molded and molded biaxially with an LB-01 molding machine manufactured by CORPOPLAST. Get a bottle.

Cut the body of the bottle and use a haze meter NDH-20D manufactured by Nippon Denshoku Co., Ltd.
The haze of the test piece is measured by a method according to STM D1003.

[0027]

Example 1 Naphthalene-2,6-dicarboxylic acid 122
Parts and 62 parts of ethylene glycol were charged into an esterification tank and an esterification reaction was carried out at 270 ° C., and when the esterification rate was 96% and the product [η] was 0.1, germanium oxide was obtained. 0.016 part and 0.043 part of orthophosphoric acid were added, and it moved to the polymerization reaction tank.

After reacting under normal pressure at 270 ° C. for about 10 minutes,
Under high vacuum (high vacuum of several mmHg or more) for about 100 minutes. The intrinsic viscosity of the obtained polymer is [η] =
At 0.65, Colb was -0.5.

The polymer thus obtained is discharged from the polymerization tank while cutting it into pellets, and the pellets are further subjected to high vacuum (several mmHg) in a solid-state polymerization reactor.
The reaction was carried out at 220 ° C. for about 6 hours. The resulting pellets had an intrinsic viscosity [η] of 0.75 and an oligomer content of 0.3 wt%.

The bottle formed using the pellets had good transparency, and the haze of the formed bottle piece (body portion) was 1.8%.

[0031]

Comparative Example 1 122 parts of dimethyl-2,6-naphthalenedicarboxylate, 62 parts of ethylene glycol and 0.086 part (80 mmol%) of magnesium acetate were charged into a transesterification reactor, and the transesterification was carried out at 170 to 235 ° C. went. When no distillate was generated, 0.016 part of germanium oxide and 0.043 part of orthophosphoric acid were added, and the mixture was transferred to a polymerization reactor. The reaction was carried out at 260 to 270 ° C for about 10 minutes under normal pressure, and then at 290 ° C under high vacuum (several mm).
The reaction was carried out at a high vacuum of at least Hg for 100 minutes. The intrinsic viscosity [η] of the obtained polymer was 0.65, and Colb was 0.5.

Further, the intrinsic viscosity and oligomer of the pellet obtained by solid phase polymerization in the same manner as in Example 1 were [η] = 0.75 and the amount of oligomer was 0.3 wt%, respectively. In addition, the haze of the bottle piece was as large as 5.5%, and whitening apparently due to crystallization was observed in the bottle.

[0033]

Comparative Example 2 The same procedure as in Example 1 was carried out except that antimony trioxide was used as a polymerization catalyst in an amount capable of polymerizing under the same reaction conditions as in Example 1 instead of the germanium oxide catalyst. The hue of the obtained polymer having [η] = 0.65 after melt polymerization was not preferable, and Colb was 1.0.

[Η] of the pellet after the solid phase polymerization is 0.75
The amount of the oligomer was 0.3 wt%, which was the same as that of Example 1. However, the bottle after molding was observed to be cloudy, which is considered to be due to the effect of the regenerated oligomer, and the haze of the bottle piece was actually as poor as 4.8%.

[0035]

Comparative Example 3 In Example 1, the polymerization temperature and reaction time were the same as in Example 1 except that the degree of vacuum in the polymerization reaction tank was changed to high vacuum. 75
And The amount of oligomer in the pellets was as high as 0.6 wt%, the transparency of the molded bottle was poor, and the haze of the bottle piece was actually as bad as 7.2%.

The results of Example 1 and Comparative Examples 1 to 3 are summarized in Table 1.

[0037]

[Table 1]

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-36867 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 63/00-63/91

Claims (2)

(57) [Claims] 1. Esterification of a dicarboxylic acid mainly composed of naphthalene-2,6-dicarboxylic acid and a glycol mainly composed of ethylene glycol, followed by polycondensation using a germanium compound as a catalyst. A method for producing a bottle-forming polyester having an intrinsic viscosity of 0.5 or more and less than 1.0, comprising a solid-state polymerization step of suppressing the amount of oligomers contained to 0.4% by weight or less. 2. The method of claim 1, wherein the germanium compound is at least one selected from the group consisting of germanium oxide, germanium hydroxide, germanium alcoholate and germanium halide.
The method for producing a bottle-forming polyester according to claim 1, which is a seed.