JP3267902B2 - Polyester resin - 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 resin, and more particularly, to a polyester resin having good heat stability, excellent hue and transparency, and suitable for packaging materials.

[0002]

2. Description of the Related Art Polyester copolymers (hereinafter sometimes abbreviated as PENT) comprising naphthalenedicarboxylic acid units and terephthalic acid units as acid components and ethylene glycol units as diol components are polyethylene terephthalate (hereinafter abbreviated as PET). Basic properties such as UV-cutting property, heat resistance, gas barrier property, chemical resistance, etc.

[0003] From this, it is expected that PENT is useful as a packaging material for bottles (containers), sheet materials and the like when used in a blend with PET or alone.

[0004] Among packaging materials, materials used in beverage bottles such as juices are strongly required to have excellent hue and transparency in view of commercial value.

[0005] Compared with polyethylene naphthalene dicarboxylate (hereinafter sometimes abbreviated as PEN), PENT has less decrease in basic physical properties, and transparency is ensured by compatibilization when blended with PET. It is easy and costs can be reduced.

[0006] PENT can be obtained by a polymerization reaction basically using the same catalyst as PET. In particular, it is expected that antimony trioxide is effective as a polymerization catalyst from the viewpoint of cost.

However, compared to PET, PENT is liable to be whitened by blow-stretching or the like at the time of bottle molding, and in our research, there is a problem that a sufficiently satisfactory bottle (product) cannot be obtained in terms of transparency. Expected to be likely.

According to the findings of the inventors, as a result of elucidating the cause of the whitening, it is presumed that the internal haze is caused by the catalyst precipitate caused by the catalyst and the crystallization is induced by the catalyst precipitate particles. You.

[0009] In particular, in the case of PENT, it is presumed that the stress at the time of forming (stretching) the bottle is much larger than that of PET, and that the influence is likely to occur.

That is, in order to suppress whitening, it is necessary to reduce the amount of precipitates caused by a catalyst or the like. As a means for this, it has been proposed to limit the type, amount and ratio of a specific catalyst (Japanese Unexamined Patent Publication No. No. 258394), the transparency of PENT for this catalyst system was certainly improved.

[0011]

However, hue and thermal stability are not sufficiently satisfactory. According to the findings of the present inventors, the cause is that the amount of the phosphorus compound used for deactivating the transesterification catalyst is smaller than the equimolar amount in order to suppress the formation of the precipitate. In this case, the catalytic action is not completely deactivated, and the rate of decomposition of the polymer is increased when the polymer is molded.

If the melt viscosity of the polymer is not appropriate at the time of molding the bottle, the smoothness and uniform thickness distribution of the bottle surface cannot be ensured, or the haze is remarkably deteriorated, and clouding occurs.

[0013] If the amount of acetaldehyde in the polymer is large, an unpleasant odor due to acetaldehyde is generated in the bottle filling.

It is an object of the present invention to provide a polyester resin having good thermal stability, excellent hue and transparency, a reduced amount of regenerated acetaldehyde due to a decrease in molding temperature, and transparency can be secured in a short molding cycle. It is an object of the present invention to obtain a polyester resin having a reduced unpleasant odor in a bottle filling when made into a bottle.

[0015]

That is, according to the present invention, a naphthalenedicarboxylic acid unit is contained in an amount of 95 to 85 mol% as an acid component.
A polyester comprising 5 to 15 mol% of terephthalic acid units and ethylene glycol units as a diol component, and cobalt and manganese as elements derived from the compound used as a catalyst, and elements derived from the compound used as a stabilizer And Sb ₂ O ₃ derived from the catalyst, the content of which is represented by the following formula (1)
It is a polyester resin that simultaneously satisfies (4). 2 ≦ Co ≦ 20mmol% (1 ) 10 ≦ Mn ≦ 60mmol% (2) 0.7 ≦ P / (Co + Mn) ≦ 1.5 (3) 5 ≦ Sb 2 O 3 ≦ 40mmol% (4) ( where the Each element of Co, Mn and P and Sb ₂ O ₃ in the formulas are amounts based on the acid component.)

Hereinafter, the present invention will be described in detail. The polyester of the present invention contains 95 to 85 mol% of a naphthalenedicarboxylic acid unit and 5 to 15 mol% of a terephthalic acid unit as an acid component. If the terephthalic acid unit exceeds 15 mol%, the amorphousness becomes strong, and crystallization and drying during molding and solid-state polymerization are difficult. If the terephthalic acid unit is less than 5 mol%, the melting point of the polyester of the present invention is high, the molding temperature cannot be lowered, and the amount of regenerated acetaldehyde increases. Furthermore, in this case,
It takes time to compatibilize with PET to ensure transparency, and it is difficult to shorten the molding cycle.

In the present invention, an ethylene glycol unit is used as a glycol component, and part of the ethylene glycol unit is, for example, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentyl glycol, diethylene glycol, 1,1- Cyclohexane dimethanol, 1,
4-cyclohexanedimethanol, 2,2-bis (4
Copolymers substituted with at least one other polyfunctional compound such as' -β-hydroxyphenyl) propane or bis (4'-β-hydroxyethoxyphenyl) sulfonic acid and copolymerized in a range of less than 10% by weight It may be.

When the polymer is polymerized by the transesterification method, the lower alkali ester of naphthalenedicarboxylic acid and the lower alkali ester of terephthalic acid as the acid component and the ethylene glycol as the glycol component are added to the total amount of the acid component. A cobalt compound containing ２０20 mmol% of cobalt element and a manganese compound containing 10 to 60 mmol% of manganese element are added as a transesterification catalyst.

Here, the purpose of adding the cobalt compound is to suppress the yellowing which is the cause of the hue deterioration, in addition to the effect of the transesterification catalyst. Addition amount is 2mm
If the amount is less than ol%, this effect is not exhibited, and if it exceeds 20 mmol%, the hue becomes gray and the hue is deteriorated.

When the total amount of the manganese compounds exceeds 60 mmol%, a whitening phenomenon is observed at the time of molding due to the effect of precipitated particles due to the catalyst residue, resulting in poor transparency. Conversely, if it is less than 10 mmol%, not only the transesterification reaction becomes insufficient, but also the subsequent polymerization reaction becomes slow.

Further, a phosphorus compound is added to deactivate the transesterification catalyst. The addition amount (molar ratio) of the phosphorus compound is the total addition amount 1 of the cobalt compound and the manganese compound.
Must be in the range of 0.7 to 1.5. If the molar ratio is less than 0.7, the transesterification catalyst will not be completely deactivated and the thermal stability will be poor, resulting in inconvenience that the polymer will be colored or the physical properties during molding will be reduced.
Conversely, if it exceeds 1.5, the thermal stability is poor.

The manganese compound and the cobalt compound used in the present invention include, for example, oxides, chlorides, carbonates,
It can be used as a carboxylate. Among them, acetates, that is, manganese acetate and cobalt acetate are preferable.

Examples of the phosphorus compound include trimethyl phosphate, triethylene phosphate or tri-n-butyl phosphate and orthophosphoric acid. Preferably it is trimethyl phosphate.

As a polymerization reaction catalyst, antimony trioxide is used in terms of hue. If the amount of antimony trioxide is less than 5 mmol%, the polymerization reactivity is low and the productivity is poor, and if it exceeds 40 mmol%, thermal stability is inferior and physical properties during molding and color hue are deteriorated. 40 mmol%
Must be in the range

It is preferable that all of the above-mentioned various catalysts and stabilizers are added during the period from the start of the transesterification reaction to the initial stage for the cobalt compound and the manganese compound. On the other hand, the phosphorus compound can be added until the intrinsic viscosity reaches 0.3 after the transesterification reaction is substantially completed.

The antimony compound is added at least 10 minutes before the addition of the phosphorus compound and until the intrinsic viscosity reaches 0.2.

In the polyester resin of the present invention, the intrinsic viscosity [η] of the polyester resin obtained by melt polymerization is used.
Preferably satisfies the following expression (5). 0.40 ≦ [η] ≦ 0.63 (5)

If the intrinsic viscosity is lower than 0.40, cracks or the like are caused when chips are formed, and if it is higher than 0.63, the polymerization time is prolonged and the hue is deteriorated.

In the present invention, the polyester resin thus obtained is preferably subjected to solid-phase polymerization so that the intrinsic viscosity [η] of the polyester resin satisfies the following formula (6). Known methods can be used for the solid phase polymerization. 0.65 ≦ [η] ≦ 0.85 (6)

When the intrinsic viscosity is less than 0.65 or 0.8
If it exceeds 5, the transparency at the time of forming the bottle and the shape of the bottle are deteriorated, which is not preferable.

[0031]

The present invention will be described more specifically with reference to the following examples. In the examples, "parts" means parts by weight. (1) Intrinsic viscosity ([η]): Measured at 35 ° C. as a mixed solvent of tetrachloroethane: phenol = 4: 6. (2) Col-L, b (hue): The polymer was heat-treated at 160 ° C. for 90 minutes in a drier to crystallize, and then measured using a color machine CM-7500 type color machine. (3) Haze (transparency): After drying the polymer at 160 ° C. for 5 hours, a preform of 55 g was molded at a molding temperature of 300 ° C. using an injection molding machine 100DM manufactured by Meiki Seisakusho,
This is blow-stretched, and the inner volume is 1.5 l and the body thickness is 300 μ
m bottle. The haze of the bottle body was measured with a turbidity meter manufactured by Nippon Denshoku Industries Co., Ltd. (4) Acetaldehyde content (abbreviated as AA): The sample was freeze-pulverized and then measured by HS-GC (manufactured by Hitachi, Ltd.). (5) Element content of polymer Measured by X-ray fluorescence by a standard method.

Example 1 227 parts of 2,6-naphthalenedicarboxylic acid dimethyl ester (hereinafter may be abbreviated as NDC), dimethyl terephthalate (hereinafter DM)
T) and 14 parts of ethylene glycol (hereinafter sometimes abbreviated as EG) and cobalt acetate tetrahydrate (hereinafter sometimes abbreviated as Co).
Using 025 parts of manganese acetate monohydrate (hereinafter sometimes abbreviated as Mn) as a transesterification catalyst and subjecting it to a transesterification reaction according to a conventional method, antimony trioxide (hereinafter abbreviated as Sb). After adding 2.92 parts of a 1% solution of ethylene glycol (hereinafter abbreviated as EG) of 1%, 0.07 part of trimethyl phosphate (hereinafter may be abbreviated as P) is added, The transesterification was terminated. Next, a polycondensation reaction was continuously performed under high temperature and high vacuum as usual, and then a strand type chip was obtained. The intrinsic viscosity of the obtained polymer was 0.5, and the polymerization time was 70 minutes. Further, this prepolymer was solid-phase polymerized by a conventional method. The intrinsic viscosity of the obtained polymer is 0.7 and the amount of acetaldehyde is 3 p.
pm.

Examples 2 to 5, Comparative Examples 1 to 10
Example 1 was repeated except that the amounts and ratios of naphthalenedicarboxylic acid dimethyl ester, dimethyl terephthalate, cobalt acetate tetrahydrate, manganese acetate tetrahydrate, trimethyl phosphate and antimony trioxide were changed as shown in Table 1. Performed similarly to 1. Table 1 also shows the obtained polymer quality and each evaluation result.

[0034]

[Table 1]

[0035]

Industrial Applicability The polyester resin of the present invention has good thermal stability, is excellent in hue and transparency, is suitable for packaging materials, has little whitening (cloudiness) when forming a bottle, and can be a bottle product having high commercial value.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-10-292036 (JP, A) JP-A-9-77859 (JP, A) JP-A-7-258394 (JP, A) (58) Field (Int. Cl. ⁷ , DB name) C08G 63/00-63/91

Claims (3)

(57) [Claims] 1. An acid component comprising 95 to 85 mol% of naphthalenedicarboxylic acid units and 5 to 1 of terephthalic acid units.
5 mol% and a polyester composed of ethylene glycol units as a diol component, wherein cobalt and manganese as elements derived from the compound used as the catalyst, phosphorus as an element derived from the compound used as the stabilizer, and catalyst derived A polyester resin containing the following Sb ₂ O ₃ , the content of which satisfies the following formulas (1) to (4) at the same time. 2 ≦ Co ≦ 20mmol% (1 ) 10 ≦ Mn ≦ 60mmol% (2) 0.7 ≦ P / (Co + Mn) ≦ 1.5 (3) 5 ≦ Sb 2 O 3 ≦ 40mmol% (4) ( where the Each element of Co, Mn and P and Sb ₂ O ₃ in the formulas are amounts based on the acid component.) 2. The polyester resin according to claim 1, which is a polyester resin obtained by melt polymerization and has an intrinsic viscosity ([η]) satisfying the following formula (5). 0.40 ≦ [η] ≦ 0.63 (5) 3. The polyester resin according to claim 1, which is a polyester resin obtained by subjecting a polyester resin obtained by melt polymerization to solid phase polymerization, and having an intrinsic viscosity ([η]) satisfying the following formula (6). . 0.65 ≦ [η] ≦ 0.85 (6)