JP2658567B2 - Composite polyester film - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a composite polyester film having excellent transparency and good slipperiness and excellent workability, and relates to a packaging film and various industrial films. It is useful as a film for use.

(Prior art) Polyester films are excellent in transparency, mechanical strength, heat resistance, cold resistance, chemical resistance, insulation, dimensional stability, etc., and are widely used as packaging films and various industrial films. Used in the field. As one of them, taking advantage of the transparency of polyester film, aluminum, silver and other metals are vapor-deposited to develop excellent gloss, for food packaging,
It is used for decoration, gold and silver thread, transfer, etc. However, in order to further improve the transparency, it is necessary to reduce the number of fine particles for ensuring the slipperiness and to reduce the voids generated between the fine particles and the polymer, but the slipperiness is reduced. is there. As described above, it is not easy for a polyester film to have both contradictory characteristics of high transparency and easy sliding.

Other means of imparting lubricity to the film include roughening of the film surface by chemical or physical treatment such as chemical treatment or embossing, but there is a problem of lowering the transparency intended for this purpose. . Further, as another means, there is a method of coating a particulate lubricant on one side or both sides of the film during or after the film forming process, but the coated film may have a slippery surface depending on use conditions. In addition, there is a problem that various kinds of processing may cause a problem, and there is a problem that a cost is increased due to an increase in a coating process.

(Problems to be Solved by the Invention) The present invention is intended to solve the above-mentioned conventional problems, and an object of the present invention is to provide a film having excellent transparency and excellent slipperiness and excellent film winding property and workability. The object of the present invention is to provide a composite polyester film having:

(Means for Solving the Problems) In the composite polyester film of the present invention, an easy lubricating layer containing 0.01 to 0.08% by weight of inorganic particles is laminated on at least one surface of a polyester film containing substantially no particulate lubricant. A composite polyester film, obtained by observing the particles with a scanning electron microscope, represented by the following formula (I):
The area ratio to the circumscribed circle represented by is 60% or more, the degree of dispersion of the particle diameter of the particles is 25% or less, and the average particle diameter of the particles is 0.2 to 3 times the thickness of the easy-smooth layer. It is a composite polyester film characterized by the following.

In a preferred embodiment, the haze of the composite polyester film is 1.5 or less, the gloss is 210 or more, the narrow-angle diffuse transmission value is 2.0 or less, and the coefficient of static friction between the slippery layers is 0.3 or more.
1.4 or less.

The polyester used as the base film (base film) and the lubricating layer film of the composite polyester film of the present invention is a crystalline polyester such as polyethylene terephthalate and polyalkylene naphthalate, and is not particularly limited, but polyethylene terephthalate is particularly suitable. And, above all,
80 mol% or more is composed of ethylene terephthalate. In this case, as other copolymerization components, isophthalic acid,
p-β-oxyethoxybenzoic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-dicarboxylic diphenyl, 4,
Dicarboxylic acid components such as 4'-dicarboxylbenzophenone, bis (4-carboxylphenyl) ethane, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid, cyclohexane-1,4-dicarboxylic acid, propylene glycol, butanediol, neone Pentyl glycol, diethylene glycol, cyclohexane dimethanol, ethylene oxide adduct of bisphenol A,
Polyethylene glycol, polypropylene glycol,
Glycol components such as polytetramethylene glycol, p
-An oxycarboxylic acid component such as oxybenzoic acid can be optionally selected and used. In addition, a small amount of a compound containing an amide bond, a urethane bond, an ether bond, a carbonate bond, or the like may be contained as a copolymer component.

As the material of the inorganic and / or organic fine particles contained in the slippery layer, a substance that is insoluble in polyester is selected.

Examples of the inorganic substance include metal oxides such as silicon dioxide, titanium dioxide, and zirconium dioxide, complex oxides such as kaolinite and zeolite, and salts such as calcium sulfate, barium sulfate, calcium carbonate, and calcium phosphate. Examples of the organic substance include a silicone resin having a siloxane bond in the main chain, polystyrene, polyacrylic acid, and the like. The fine particles may be used alone or in combination of two or more.

The content of the inorganic and / or organic fine particles in the slippery layer is 0.01 to 0.1% by weight, preferably 0.03 to 0.0
8% by weight. If the amount is less than 0.01% by weight, the slipperiness of the film is insufficient and the workability is reduced. If the amount exceeds 0.1% by weight, the transparency of the film decreases.

The fine particles preferably have an area ratio calculated by the following formula (I) of 60% or more, more preferably 80% or more, and still more preferably 90% or more.

In the formula (I), the projected sectional area of the particle and the area of a circle circumscribing the particle can be obtained by observing with a scanning electron microscope. When fine particles having an area ratio of less than 60% to the circumscribed circle are used, the balance between the transparency and the slipperiness of the obtained film is reduced.

Further, it is preferable that the fine particles have a substantially uniform particle size and a particle size distribution close to monodispersion. Specifically, the degree of variation obtained by observation with a scanning electron microscope is
It is preferably at most 25%. It is more preferably at most 20%. When the variation in the particle size of the particles increases, the balance between transparency and slipperiness decreases.

Various additives may be further contained in the slippery layer. For example, a surfactant or a phosphate is contained to prevent aggregation of the fine particles. Other additives include antistatic agents, coloring agents, and the like.

Fine particles and, if necessary, various additives are mixed with the polyester resin by various methods. For example, the polyester resin and the fine particles can be mixed by a method of adding fine particles in a polymerization step of the polyester: or a method of adding fine particles when kneading the polyester in a pusher. In order to disperse uniformly in the slippery layer, the following method is preferable.

In this method, it is preferable to add the fine particles while the viscosity of the resin is low, that is, before the prepolymer is formed. When adding the fine particles, the fine particles are preferably dispersed in an appropriate medium and added. The medium is preferably a liquid substance among the components of the polyester to be prepared. The method for dispersing the fine particles in the medium is not particularly limited, and one or more of common dispersion methods such as a high-speed stirring method, a homogeneous high-pressure dispersion method, and a sand mill method can be used in combination. In the method of kneading the fine particles with a resin, it is also recommended to adopt a master batch method. When an additive is contained, it is added together with the fine particles in the method described in, for example.

In the laminated film of the present invention, the lubricating layer containing the above particles can be laminated on at least one surface of the base film by various methods. For example, each of (1) a polyester raw material (A) used as a base film and a polyester raw material (B) used as a slippery layer film in a pusher or the like,
There is a method of laminating the unstretched films which are separately melted at a temperature equal to or higher than the melting point and extruded from the die outlet and molded together in a heated state. There is a method of laminating the other molten film. : Still another method is (3) a method in which an unstretched film is formed by extruding from a die outlet in a state of being laminated by a co-extrusion method.

The laminated film thus obtained is stretched in one direction or two directions at a temperature not lower than the secondary transition point of the polyester. This stretching ratio is at least 1.
It is 5 times or more, preferably 3 to 5 times, and in the case of biaxial stretching, the stretching area is 2 to 30 times, preferably 9 to 20 times. The biaxial stretching of the film may be sequential stretching or simultaneous stretching. Further, relaxation and heat treatment are performed if necessary.

(Example) An example of the present invention will be described below. In Examples and Comparative Examples, all parts are by weight unless otherwise indicated. The average particle diameter, the degree of dispersion, and the area ratio to the circumscribed circle of the fine particles used in the present invention are as follows:
And (b). Further, the obtained laminated sheets were evaluated by the methods (c) to (e).

(A) Average particle diameter of fine particles and degree of variation in particle diameter Scanning electron microscope (Hitachi S-510)
Is used to take a photograph, and this is enlarged and copied. Further tracing is performed, and the image corresponding to 200 particles is randomly filled in black. This image is measured for the Feret diameter in the horizontal direction using an image analyzer (Lirex 500 type, Nireco Corporation), and the average value is defined as the average particle diameter. The degree of variation in particle diameter is calculated by the following equation.

(B) Area ratio to circumscribed circle 20 particles are arbitrarily selected from the trace image used for the measurement of the average particle diameter, and the projected sectional area of each particle is calculated as follows:
The measurement is performed by the image analyzer used in (a). The area of a circle circumscribing the particles is calculated, and the area ratio is determined using the following equation.

(C) Transparency of film (i) Haze A haze value is measured with an integrating haze meter manufactured by Toyo Seiki Co., Ltd. according to JIS KG714.

(Ii) LSI The LS value (narrow-angle diffuse transmission value) is measured with a visual transparency tester manufactured by Toyo Seiki Co., Ltd.

(D) Slip property of the film The static friction coefficient between the slippery layer surfaces is measured under the conditions of 23 ° C., 65% RH and a tensile speed of 200 mm / min according to ASTM-D-1894-63T.

(E) Film gloss According to JIS Z-8741, a gloss value of 45 ° is measured with a gloss meter manufactured by Nippon Denshoku Industries Co., Ltd.

Example 1 Two extruders were connected to one T-die, one extruder was charged with substantially lubricant free polyethylene terephthalate (A) (IV; 0.62) for the substrate layer, In the other extruder, polyethylene terephthalate (B) (IV; 0.62) containing 0.06% by weight of silica (average particle diameter 0.7 μm, degree of variation 14%, area ratio to the circumscribed circle 96%) for the slippery layer was used.
Is melted at a temperature of 285 ° C., and three layers (smooth layer / base layer / easy layer) of a laminated resin are extruded from a T-die, and cooled and solidified on a rotating cooling roll (25 ° C.). To form a laminated unstretched sheet. The unstretched sheet was heated to 85 ° C. and stretched 3.5 times in the sheet advancing direction between two sets of rolls having different rotation speeds. The obtained uniaxially stretched film was fed to a tenter type transverse stretching machine, and stretched 3.9 times in a direction orthogonal to the above while heating at 95 ° C. Next, this film was treated with hot air at 225 ° C. while being relaxed by 3.5% and wound up. Table 1 shows the properties of the obtained film.

The film obtained in this example is excellent in transparency and gloss,
It was of high quality with excellent slipperiness.

Examples 2 to 3 The same as Example 1 except that the fine particles in the slippery layer in Example 1 were changed as shown in Table 1. The resulting film was of high quality with excellent transparency and gloss and excellent slipperiness.

Example 4 Example 4 was the same as Example 1 except that the fine particles in the slippery layer and the thickness of the slippery layer in Example 1 were changed as shown in Table 1. The resulting film was of high quality with excellent transparency and gloss and excellent slipperiness.

Example 5 Example 5 was the same as Example 1 except that the total thickness of the film in Example 1 was changed as shown in Table 1. The resulting film was of high quality with excellent transparency and gloss and excellent slipperiness.

Comparative Example 1 The same as Example 1 except that the thickness of the slippery layer in Example 1 was changed as shown in Table 1. The resulting film was inferior in transparency and gloss.

Comparative Example 2 The same as Example 1 except that the thickness of the slippery layer in Example 1 was changed as shown in Table 1. The obtained film had poor slippery quality.

Comparative Example 3 Example 1 was the same as Example 1 except that the amount of fine particles in the slippery layer in Example 1 was changed as shown in Table 1. The obtained film had poor slippery quality.

Comparative Example 4 Example 1 was the same as Example 1 except that the amount of fine particles in the lubricating layer was changed as shown in Table 1. The resulting film was inferior in transparency and gloss.

Comparative Example 5 The same operation as in Example 1 was performed except that the fine particles in the lubricating layer in Example 1 were changed as shown in Table 1. The obtained film had poor slippery quality. These fine particles have a large degree of variation in particle diameter when observed with a scanning electron microscope, and it is difficult to measure the area ratio with respect to a circumscribed circle. A Coulter counter (manufactured by Coulter Electronics)
50% integrated when measured with an aperture diameter of 50 μm
The diameter was 1.8μ. The particles were observed with a phase-contrast microscope (manufactured by Nikon), and the area ratio to the circumscribed circle was measured by the same method as in the case of the scanning electron microscope. The result was 53%.

(Effect of the Invention) As described above, the composite polyester film of the present invention is excellent in transparency and slipperiness, exhibits excellent gloss when metal is deposited, and is excellent in workability and workability for packaging. It can be suitably used as a film or various industrial films.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-84445 (JP, A) JP-A-63-120646 (JP, A) JP-A-1-176556 (JP, A) 14107 (JP, B2)

Claims (1)

(57) [Claims] An inorganic particle is present on at least one side of a polyester film substantially free of a particulate lubricant.
A composite polyester film in which a slippery layer containing 08% by weight is laminated, wherein the area ratio of the particles to a circumscribed circle represented by the following formula (I) obtained by observation with a scanning electron microscope is 60%. With the above, the degree of dispersion of the particle diameter of the particles is 25%
Or less, and the average particle diameter of the particles is 0.2
A composite polyester film characterized by having a thickness of up to three times.