JP3396995B2 - Film made of polyester composition - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates is related to the polyester composition and films, particularly, formed of a low molecular weight material content of less heat resistance, electrical properties, the polyester composition excellent in mechanical properties Film It is about.

[0002]

2. Description of the Related Art Polyester, especially polyethylene terephthalate (hereinafter referred to as PET) has excellent mechanical properties,
Widely used in industrial applications due to its thermal and electrical characteristics,
Demand is also increasing. However, as the applications and demands expand, the properties required of polyesters are becoming more and more severe in each application field.

One of those required properties is a polyester molded product having a low content of low molecular weight substances (hereinafter referred to as oligomers).

Particularly, a PET molded product usually contains 1 to 1.3% by weight of an ethylene terephthalate cyclic trimer (hereinafter referred to as a cyclic trimer). Such low-molecular weight substances may cause contamination of the mouthpiece and film loss, but especially when used for electrical insulation of closed type motors for refrigerators, the low-molecular weight substances are generated from the polyethylene terephthalate film due to the refrigerant in the motor. Is extracted, and the cyclic trimer therein is deposited in various places of the refrigerator, which causes trouble. Therefore, at present, there is a demand for a film having an amount of the cyclic trimer of 0.5 wt% or less, although it depends on the type of refrigerator.

As a method for obtaining a film having a low cyclic trimer content, as described in JP-A-54-62277, a method of dipping the film in a solvent such as xylene to extract an oligomer, JP-A-63-19764
As described in Japanese Patent Publication No. 3, a method of suppressing the precipitation of oligomers by using a laminated film has been proposed, but in both cases, the productivity is remarkably inferior and the processability is also problematic.

In order to obtain such a film, there is known a method in which a polymer chip is subjected to solid phase polymerization to reduce a cyclic trimer, and then melt extrusion is carried out to form a film.
Japanese Unexamined Patent Publication (Kokai) No. 3-281526 discloses a method of further deactivating the transesterification reaction catalyst and limiting the increase amount at the time of melting by defining the amount of phosphorus compound in the catalyst system within a certain range. However, it was insufficient in that the catalyst was not sufficiently deactivated and the increase of the cyclic trimer during melt extrusion could not be sufficiently suppressed. Further, in JP-A-5-186571, the content of antimony atoms is regulated within the range of 150 to 300 ppm to lower oligomers, but this is also a cyclic trimer at the time of melt extrusion. It was insufficient in that the increase could not be suppressed sufficiently.

[0007]

OBJECTS OF THE INVENTION It is an object of the present invention is to provide less low molecular weight material content, and hydrolysis resistance, insulating properties, a film comprising a polyester composition excellent in mechanical properties .

[0008]

The above-mentioned object of the present invention is a polyester in which 90 mol% or more comprises ethylene terephthalate units, and the polymerization catalyst metal compound is an antimony compound.
0.2 mol / ton of metal to the polyester
Or more and 1 mol / ton or less, and the ethylene terephthalate cyclic trimer content is 0.4 with respect to the polyester.
Polyester composition characterized by less than wt%
It is composed of and maintains the elongation at break in heat resistance test at 160 ℃.
The half-life is over 700 hours.
It is achieved by the film .

In the polyester of the present invention, it is preferable that the ethylene terephthalate component is 90 mol% or more based on the polyester from the viewpoints of heat resistance and mechanical properties. May be copolymerized within the range of 10 mol%. Examples of the dicarboxylic acid component which can be copolymerized include isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid,
2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, 4,4′-diphenylsulfonedicarboxylic acid and the like can be mentioned. Moreover, 1,4-cyclohexanedicarboxylic acid etc. can be mentioned as an alicyclic dicarboxylic acid component which can be copolymerized. As the diol component, ethylene glycol, 1,2-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1 , 2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2-bis (4'-β-hydroxyethoxyphenyl) propane, etc. The aliphatic, alicyclic, aromatic diols and the like can be mentioned. These components may be used alone or in combination of two or more.

The polyester of the present invention can be produced by a conventionally known method for producing polyester. That is, a dialkyl ester is used as an acid component, and a transesterification reaction between the dialkyl ester and a diol component is performed, and then a product of this reaction is heated under reduced pressure to polycondensate while removing an excess diol component. can do. It can also be produced by a conventionally known direct polymerization method using dicarboxylic acid as the acid component. As the reaction catalyst, conventionally known titanium compounds, lithium compounds, calcium compounds, magnesium compounds, antimony compounds, germanium compounds and the like can be used. These reaction catalysts are preferable in suppressing the increase amount of the cyclic trimer during melt extrusion because the smaller the amount of the transesterification reaction, the less the transesterification reaction occurs. It takes a long time to do so, which is not preferable in terms of productivity. Conversely, no matter how much polymerization catalyst is added, the amount of cyclic trimer that can be reached by solid phase polymerization is
Since it is a value determined by the reaction equilibrium value of the linear polymer and the ring and the ultimate crystallinity, etc., there is a limit, so it cannot be lowered below a certain amount, so it is possible that an extra catalyst has been added. However, in this case, no matter how much the productivity is increased, the increased amount at the time of melt extrusion is increased, so that a film having a sufficiently low cyclic trimer amount cannot be obtained. The polymerization catalyst metal compound, the decrease behavior during solid phase polymerization of the cyclic trimer, and the increase behavior during melt extrusion were analyzed, and as a result of diligent study on the optimum catalyst amount, the result was selected from antimony, germanium, and titanium compounds in the polyester. When the amount of the polymerization catalyst metal compound used is within the specific range specified in the present invention, surprisingly, the rate of oligomer increase is remarkably suppressed even in the case of melt film formation without inhibiting productivity at all. It was found that a polyester composition and a film having an extremely low oligomer content can be obtained. In the polyester of the present invention, in order to reduce the increase in cyclic trimer at the time of melt extrusion film formation, the amount of such metal compound needs to be 1 mol / ton or less as the metal amount, and the film after film formation is frozen. In order to completely prevent troubles due to oligomers when used for insulation of machine compressors, it is preferably 0.9 mol / ton or less, more preferably 0.8 mol / ton or less. Further, in order to prevent the time required for the solid phase polymerization step for sufficiently reducing the cyclic trimer from becoming too long, it is preferable that the amount of these polymerization catalyst metal compounds is 0.2 mol / ton or more as a metal. , And more preferably 0.25 mol / ton or more.

By subjecting the polyester thus obtained to solid phase polymerization, the degree of polymerization can be further increased and the cyclic trimer can be reduced. The polyester of the present invention obtained through this solid phase polymerization must have an ethylene terephthalate cyclic trimer content of less than 0.4% by weight in order to obtain a film having a sufficiently small amount of cyclic trimer. Therefore, in order to completely prevent troubles due to oligomers when the film after film formation is used for insulation of a refrigerator / compressor, the content is more preferably less than 0.3% by weight.

Among antimony, germanium, and titanium compounds, antimony metal compounds are more preferable because they have a small amount of diethylene glycol by-produced and are excellent in heat resistance.

The solid phase polymerization is carried out in a dryer at a temperature of 200 ° C. to 250 ° C. under a reduced pressure of 1 torr or less or under a nitrogen stream.
At this time, since it is considered that the cyclic trimer can exist only in the amorphous part, in this solid phase polymerization step, the amorphous trimer which can exist in the amorphous phase can be formed by sufficiently increasing the crystallinity and increasing the density. It is important to keep the area small. From this point, the density of the polyester of the present invention is 1.39 g / cm ^3.
It is preferably at least 1.40 g / cm ³ or more, in order to obtain a polyester having a sufficiently low cyclic trimer content.

The polyester thus obtained is
According to a conventional method, after drying, melt extrusion is performed to obtain an unstretched sheet, followed by biaxial stretching and heat treatment,
A biaxially stretched film can be completed. Biaxial stretching may be either longitudinal or transverse sequential stretching or biaxial simultaneous stretching, and the stretching ratio is not particularly limited, but usually 2.0 to 5.0 times both longitudinal and transverse are suitable. Alternatively, after longitudinal or transverse stretching, it may be re-stretched in either the longitudinal or transverse direction. The cyclic trimer content of the polyester film thus obtained is preferably less than 0.6% by weight, and in order to completely prevent troubles due to oligomers when used for insulation of refrigerator compressors. Is more preferably less than 0.4% by weight. In addition, the amount of carboxyl end groups of this film has high heat resistance,
In order to obtain hydrolysis resistance, it is preferably 30 equivalents / ton or less, and more preferably 25 equivalents / ton or less in order to obtain a sufficient life of the refrigerator motor. Further, the film thus obtained preferably has a breaking elongation retention half-life of 700 hours or more in a heat resistance test at 160 ° C., and more preferably in order to avoid thermal deterioration and the like which are received during operation of the refrigerator. Is more than 800 hours.

The film of the present invention thus obtained has a small content in the film of the cyclic trimer, especially when it is used for electrical insulation of a closed type motor for a refrigerator.
The amount extracted by the refrigerant is also small, and it is possible to prevent troubles that occur because the cyclic trimer is deposited in various places of the refrigerator and becomes a plug. Further, since it has excellent hydrolysis resistance and heat resistance, the life of the refrigerator motor can be greatly extended.

[0016]

EXAMPLES The present invention will now be described in more detail by way of examples. The properties in the examples were measured as follows.

A. Intrinsic viscosity of polymer ([η]) It is a value measured at 25 ° C. using o-chlorophenol as a solvent.

B. Cyclic trimer content ([C3]) 100 mg of polymer was dissolved in 5 ml of orthochlorophenol and measured by liquid chromatography (Model 8500 Varian), and the ratio (% by weight) to the polymer was shown.

C. Elements contained in polymer Measured by fluorescent X-ray method [TFK3064 type (manufactured by Geiger Flex Co.)].

D. Carboxyl end group concentration 0.5 g of polymer chips were dissolved in o-cresol and titrated with potassium hydroxide.

E. Density of Chip A density gradient tube was prepared using a mixed solvent of carbon tetrachloride and n-heptane, and the density gradient tube was determined using this.

F. The heat-resistant film sample was heat-treated in a hot air oven at a temperature of 160 ° C., sampled to measure the elongation at break, and broken at a ratio of 50% to the elongation at break of the untreated film. The elongation retention half-life was used as an index of heat resistance.

Example 1 To a mixture of 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol, 0.09 wt% of magnesium acetate and 0.008 wt% of diantimony trioxide were added with respect to the amount of dimethyl terephthalate. The temperature was raised by heating to carry out the transesterification reaction. Then, 0.026 wt% of trimethyl phosphate is added to the transesterification reaction product with respect to the amount of dimethyl terephthalate, and then the product is transferred to the polycondensation reaction layer. Then, the reaction system was gradually depressurized while heating and raising the temperature, and polymerized by a conventional method at 290 ° C. under a reduced pressure of 1 mmHg to obtain a polyester having an intrinsic viscosity [η] of 0.54. The polymer was cut into cubes with a diameter of 3 mm, and solid phase polymerization was carried out by subjecting the polymer to heat treatment at 225 ° C. for 30 hours under a reduced pressure of 1 mmHg using a rotary vacuum polymerization apparatus, and an intrinsic viscosity [η] 1.1, A polyester having a density of 1.41 g / cc and a cyclic trimer content of 0.24% by weight was obtained. As a result of elemental analysis in the obtained polyester, the amount of antimony metal was 0.53 mol / ton. Then, an unstretched polyester film of 1 mm was obtained with a 40 mm melt extrusion film-forming machine at a set temperature of 290 ° C. and a residence time of 8 minutes. This was biaxially stretched under ordinary conditions to obtain a 250 μm biaxially oriented polyester film. The cyclic trimer content of the film was 0.35 wt%, the carboxyl end group was 19 equivalents / ton, and the breaking elongation retention half-life used as an index of heat resistance was 1000 hours. The results are shown in the table.

[0024]

[Table 1]

Examples 2 and 3 Polymerization, solid phase polymerization and film formation were carried out in the same manner as in Example 1 except that the amount of antimony catalyst was changed so that the amount of metal was the amount shown in the table. As shown in the table, a sufficiently satisfactory film is obtained with respect to the amount of cyclic trimer in the film.

Example 4 Example 2 except that the solid phase polymerization time was shortened (15 hours).
Polymerization, solid phase polymerization, and film formation were performed in the same manner as in. The density is considered to be due to the short solid phase polymerization time, but it is slightly low, and the cyclic trimer in the chip is not sufficiently reduced. Therefore, the cyclic trimer in the film was slightly higher than that in Example 1. .

Reference Examples 1 and 2 Polymerization, solid-state polymerization and film formation were carried out in the same manner as in Example 1 except that germanium oxide and tetraethyleneglycoxide titanium were used as the polymerization catalyst species. As shown in the table, a film having a small amount of cyclic trimer and excellent heat resistance was obtained.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that the amount of antimony oxide in the polymerization catalyst was changed to the amount shown in the table, and a film was formed without solid phase polymerization. Low density, many cyclic trimers,
It seems that the amount of carboxyl end groups was large, but the heat resistance was also insufficient.

Comparative Example 2 Polymerization, solid phase polymerization and film formation were carried out in the same manner as in Example 1 except that the amount of antimony oxide in the polymerization catalyst was changed to the amount shown in the table. The cyclic trimer in the film is thought to be due to an excessive amount of polymerization catalyst, but the amount increased at the time of film formation was large and a satisfactory level could not be obtained.

Comparative Example 3 Polymerization, solid phase polymerization and film formation were carried out in the same manner as in Example 3 except that the solid phase polymerization time was 10 hours. Since the solid phase polymerization was insufficient, the density was not sufficiently high, the amount of cyclic trimer in the chip was not sufficiently low, and a satisfactory film was not obtained.

Comparative Examples 4 and 5 Polymerization, solid-state polymerization and film formation were carried out in the same manner as in Reference Examples 1 and 2 except that the amounts of the polymerization catalyst metal were changed to those shown in the table. As in Comparative Example 2, the cyclic trimer in the film is thought to be due to too much polymerization catalyst, but the amount of increase during film formation was large, and a satisfactory level could not be obtained.

Comparative Examples 6, 7 and 8 Polymerization, solid phase polymerization and film formation were carried out in the same manner as in Example 1 except that the amounts of the polymerization catalyst metal were changed to those shown in the table.
The amount of cyclic trimer seems to be due to too little polymerization catalyst, but it could not be sufficiently reduced during solid-phase polymerization, and therefore the film could not have a satisfactory level of cyclic trimer.

[0033]

INDUSTRIAL APPLICABILITY The polyester composition and film of the present invention, especially when used for electric insulation of a closed type motor for a refrigerator, have a small content in the film of the cyclic trimer, so that the refrigerant comes into contact with the film. However, the amount of the refrigerant extracted is small, and it is possible to prevent a trouble that occurs because the cyclic trimer is deposited in various places of the refrigerator and becomes a plug. Further, since it is also excellent in hydrolysis resistance, heat resistance and mechanical properties, it is possible to further extend the life of the refrigerator motor, which is very suitable.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-339351 (JP, A) JP-A-5-255492 (JP, A) JP-A-5-255491 (JP, A) JP-A-5- 170883 (JP, A) JP 5-155992 (JP, A) JP 7-207003 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 63/00-63 / 91 C08J 5/18 C08L 67/00-67/02

Claims (5)

(57) [Claims] 1. A polyester in which 90 mol% or more is composed of ethylene terephthalate units and the polymerization catalyst metal compound is an antimony compound, and the amount of the polymerization catalyst metal compound is 0.2 mo as a metal with respect to the polyester.
1 / ton or more and 1 mol / ton or less, and the ethylene terephthalate cyclic trimer content is less than 0.4% by weight based on the polyester. The polyester composition is characterized by the heat resistance test at 160 ° C.
The breaking elongation retention half-life is 700 hours or more.
Film to collect . 2. A polyester composition having a density of 1.39 g.
/ Cm ³ or more, according to claim 1, characterized in that
Film . 3. 90 mol% or more of ethylene terephthale
It is composed of a metal salt unit and the polymerization catalyst metal compound is converted to antimony.
Polyester, which is a compound of this polymerization catalyst metallization
The amount of the compound is 0.2 mo as a metal with respect to the polyester.
or less l / ton or 1 mol / ton, ethylene terephthalate cyclic trimer content of Ri <br/> Oh less than 0.6 wt%, the breaking elongation retention ratio heat test at 160 ° C.
Fill with a half-life of 700 hours or more
Mu . 4. The film according to claim 1, wherein the carboxyl terminal group concentration is 30 eq / ton or less relative to the polyester. 5. The electrically insulating film according to any one of claims 1-4.