JPS585937B2 - polyester oriented film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to oriented films of linear polyesters, such as polyethylene terephthalate, containing finely divided inert materials.

Finely divided inert materials are often added to polymeric materials to reduce the surface friction of moldings made from the materials.

In this way, by incorporating additive particles into a film of a polymeric material such as shrimp polyethylene terephthalate, so-called "
"Slidability" is increased, and as a result, ease of handling and listening performance are improved.

Addition of particles with an average particle size of 0.1 to 20 microns provides satisfactory slip properties, but tends to reduce the clarity of the oriented film due to the creation of voids around the particles.

Adding inert primary particles with small particle size to the polymer composition,
A method has also been proposed in which these particles aggregate into large secondary particles and the secondary particles act to provide desired slipperiness.

However, it has also been found that aggregates tend to collect and reduce the efficiency of filters in polymer manufacturing and extrusion systems.

According to the present invention, an oriented film of linear polyester containing from 0.05 to 0.5 weight percent of the total composition of a finely divided inert additive is provided, in which the additives include finely divided pyrolytic silica and finely divided An oriented polyester film is provided comprising a mixture of pyrolytic aluminas, each pyrolytic material having an average primary particle size of less than 100 millimicrons.

Here, these fine materials have opposite charges in the polar system.

The term "average particle size of primary particles" of fine materials refers to the average particle size of the material in its unagglomerated form, and refers to the particle size of secondary aggregates formed by agglomeration of the particles. isn't it.

The average particle size of the primary particles is the arithmetic mean of the particle diameters, and the particle diameter can be measured by electron microscopy.

In addition to secondary agglomerated particles that are formed from primary particles, e.g. as a result of physical solidification or physical or chemical affinities, agglomerates are formed as a mixture as a result of the charging of particles with opposite charges. Good too.

Linear polyesters include one or more dicarboxylic acids or lower alkyl diesters thereof and one or more glycols of the formula HO(CH2)nOH, where n
is 2 to 10).

Suitable dicarboxylic acids include terephthalic acid, isophthalic acid,
Phthalic acid, 2,5-naphthalene dicarboxylic acid, 2,6-
Naphthalene dicarboxylic acid or 2,7-naphthalene dicarboxylic acid, succinic acid, sebacic acid, adipic acid, azelaic acid, bibenzoic acid
, hexahydroterephthalic acid.

Alternatively, bis-P-carboxyphenoxyethane may be condensed with one or more of the glycols mentioned above.

Suitable glycols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol and 1,4-cyclohexanedimethanol.

Polyester may be used with any of these materials.

A preferred polyester is polyethylene terephthalate derived from terephthalic acid and ethylene glycol.

Linear polyesters, including polyethylene terephthalate, can be prepared by methods known in the art, such as direct esterification or transesterification followed by polycondensation.

Pyrolytic silica and pyrolytic alumina can be produced by flame pyrolysis of silicon tetrachloride and aluminum chloride at high temperatures, respectively.

The average particle size of pyrolytic silica and pyrolytic alumina is typically 5 to 40 millimicrons.

Pyrolytic silica has a negative charge on its surface, and pyrolytic alumina has a positive charge on its surface, and this charge promotes the formation of secondary agglomerated particles consisting of a mixture of two types of pyrolytic materials, and this secondary Agglomerated particles provide effective slip properties to uniaxially or biaxially oriented heat-set films made from polyester compositions containing them.

Pyrolytic alumina alone cannot provide good slip properties.

0.05 to 0.5 weight percent, preferably about 0.15 weight percent, of the primary particle mixture should be added to the composition to provide adequate slippage and to facilitate handling.

The total finely divided additive may contain 5 to 95 weight percent pyrogenic silica and correspondingly 95 to 5 weight percent pyrolytic alumina.

It has been found that small amounts of pyrolytic alumina, such as in the range of 10 to 20 weight percent pyrolytic alumina, promote processability and filterability.

Similar improvements in processability and filterability are provided when using higher amounts of pyrolytic alumina, but still provide a film with improved optical clarity.

Therefore, when optical clarity is important, amounts of pyrolytic alumina ranging from 30 to 95 weight percent of the total finely divided additives may be used.

Particularly in the case of polyethylene terephthalate, equal amounts of pyrolytic silica and pyrolytic alumina provide good processing and filtration properties and optical clarity.

The composition used in the present invention may be manufactured by any known method by adding fine materials to linear polyester.

For example, a slurry of a mixture of fine materials and glycol is made and then added to a military condensation mixture to produce polyester.

Polycondensation may be carried out in a conventional manner and may be preceded by conventional direct esterification methods or transesterification.

Films according to the invention can be produced by any suitable method known in the art.

A typical method is to melt extrude a polyester composition, then immediately quench it and stretch it in two directions perpendicular to each other to achieve molecular orientation.

These films are usually dimensionally stabilized by heat setting after stretching.

Molecularly oriented polyethylene terephthalate film,
A suitable method for heat setting is described in British Patent No. 8.
No. 38708.

Appropriate conditions include stretching the film by 2 times its original length in two directions.
．． Stretched 5 to 4.0 times, and in the stretched state 1
Heat set at a temperature ranging from 90°C to 240°C.

The optical clarity of the film of the present invention is exhibited in a polyethylene terephthalate film containing a biaxially stretch oriented and heat set mixture of pyrolytic silica and pyrolytic alumina.

Films made from optically clear compositions containing high amounts of alumina are particularly suitable for metallization by processes such as vacuum deposition of thin aluminum films.

Meklyzed films are clear and bright in color and do not exhibit any "bloom" in appearance.

Bloom is, for example, when measured from a narrow angle when hemetallized on a film containing conventional fine materials.
This is a phenomenon that often occurs on film.

Such metallized films are suitable for labels, textile fibres, mirrors, stamping foils, packaging and general decorative items, and laminates.

The invention is illustrated in further detail by the following examples.

EXAMPLE A mixture of pyrolytic silica and pyrolytic alumina was used as a fine additive.

Pyrolytic silica was produced by flame pyrolysis of silicon tetrachloride, and its primary particle size was 12 millimicrons.

Pyrolytic alumina was produced by flame pyrolysis of aluminum chloride, and the primary particle size was 30 millimicrons.

Ethylene glycol was added to equal weight parts of the fine silica and alumina in a ball mill to produce a slurry.

The total amount of silica and alumina is approximately 5% of the slurry.
It was expressed as a weight percentage.

A conventionally prepared bis(2-hydroxyethyl terephthalate and slurry) was introduced into a conventional polycondensation autoclave.

The system was condensed by conventional methods using an antimony trioxide catalyst at a temperature of about 285° C. and a reduced pressure of 0.5 to 1.0 mm Hg.

The amount of slurry used was determined so that the final total amount of finely divided additives was about 0.15 weight percent based on the polyethylene terephthalate composition.

No blockage occurred in the filter in the slurry processing system.

Films were prepared by melt extruding the prepared composition onto a refrigerated rotating quench drum having an abrasive surface.

On this abrasive surface, the film is immediately quenched to an amorphous state.

The quenched film was stretched 3.5 times, first in the extrusion direction and then in a direction perpendicular to the extrusion direction, at about 100°C.

The film was then heat set while still stretched at about 215°C, resulting in a final film thickness of 75 microns.

As a comparative experiment, another batch of polyethylene terephthalate was prepared using similar conditions but containing only 0.15 weight percent of pyrolytic silica with an average particle size of 12 millimicrons.

This composition was formed into a 75 micron thick biaxially oriented film under conditions similar to those used to form films containing the fine material mixture according to the invention and then heat set.

The optical properties and surface friction properties of the tested film and a control film for comparison were measured and the following results were obtained.

The Gardner haze value is a measure of the degree of haze of a film, and a lower value indicates less haze.
Measured by the standard method described in D1003-61.

Total light transmittance was measured by the ASTM D1003-61 test method.

Static friction coefficient and dynamic friction coefficient are ASTM D189
It was measured according to the test method No. 4-63, and is a measurement value of the opposite surface to one surface of the film.

The mechanical properties of the film used in the experiment were substantially the same as those of the comparison film and commercially available polyethylene terephthalate film.As a result, even with the addition of alumina/silica additives, the coefficient of friction of the film It was found that there was no effect on the total light transmittance and the total light transmittance.

The film used in the experiment was clearer to the naked eye than the control film, as reflected in the Gardner haze value and narrow angle haze value.

A sample of the test film was coated with a thin film of aluminum on one side by conventional vacuum deposition techniques.

The resulting film was particularly clear and transparent, and there was no bloom when the entire film was examined from a narrow angle.

Claims (1)

[Claims] 1 linear polyester containing from 0.05 to 0.5 weight percent of the total composition of finely divided inert additives;
In particular, the oriented film of polyethylene terephthalate is characterized in that the additive consists of a mixture of finely divided pyrolytic silica and finely divided pyrolytic alumina, each pyrolytic material having an average particle size of less than 100 millimicrons as primary particles. A linear polyester oriented film.