JPH04191045A - Composite polyester film - Google Patents

Abstract

PURPOSE:To obtain composite polyester film, which is excellent in transparency and has slipperiness excellent in the winding-up properties and workability of film, by a method wherein fine particle-containing easily sliding layer is laminated onto one side of polyester film and the areal ratio of particle to its circumcircle, degree of dispersion of particle diameter and average particle diameter are specified. CONSTITUTION:In the composite polyester film concerned, easily sliding layer, which contains 0.01-0.1wt.% of inorganic and/or organic particle, is laminated onto one side of polyester film The areal ratio of particle to its circumcircle, which is represented by the formula (I), is set to be 60% or more. The degree of dispersion of particle diameter is set to be 25% or less. At the same time, the average particle diameter is set to be 20-300% of the thickness of the easily sliding layer. If the content of fine particle becomes below 0.01wt.%, the slipperiness of film becomes insufficient and consequently the workability lowers. If said content becomes above 0.1wt.%, the transparency of the film lowers. If the areal ratio of particle becomes below 60%, the balance between the transparency and slipperiness of the film lowers. If the dispersion of the particle size becomes larger, the balance between the transparency and slipperiness lowers.

Description

Detailed Description of the Invention (Industrial Field of Use) The present invention relates to a composite polyester film that is highly workable due to its transparency and good slipperiness, and is suitable for packaging films and various other applications. Useful as an industrial film.

(Conventional technology) Polyester films are widely used as packaging films and various industrial films because of their excellent transparency, mechanical strength, heat resistance, cold resistance, chemical resistance, insulation, and dimensional stability. It is used in the demarcation area. One of the ways to do this is by taking advantage of the transparency of polyester film and depositing metals such as aluminum and silver to create excellent gloss, which can be used for food packaging,
It is used for decoration, gold and silver thread, transcription, etc. However, in order to further improve this transparency, it is necessary to reduce the number of fine particles to ensure slipperiness and to reduce the voids that occur between the fine particles and the polymer, but there is a problem that slipperiness also decreases. be. As described above, it is not easy for a polyester film to have contradictory properties of high transparency and easy slippage.

Other means of imparting slipperiness to a film include roughening the film surface through chemical or physical treatments such as chemical treatment and embossing, but this has the problem of reducing the transparency, which is the main objective. . Furthermore, another method is to coat one or both sides of the film with a particulate lubricant during or after the film forming process, but the coated film's slippery surface may peel off depending on the usage conditions. , may cause problems in various processing, and
There is also the problem that the cost increases due to the increase in the number of coated culms.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and its purpose is to provide a film with excellent transparency and slipperiness that is excellent in winding and processing properties. Our objective is to provide a composite polyester film that can be used to

(Means for Solving the Problems) The composite polyester film of the present invention is a polyester film that does not substantially contain particulate lubricant, and at least h of the polyester film contains 0.01 to 0.1 of inorganic and/or organic fine particles.
A composite polyester film laminated with a slippery layer containing % by weight, which has an area ratio of 60% with respect to the circumscribed circle represented by the following formula (I) obtained by observing the particles with a scanning electron microscope. 7, 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 of the easy slip layer thickness.
．． A composite polyester film characterized by having a thickness of 2 to 3 times.

In a preferred embodiment, the composite polyester film has a haze of 1.5 or less, a gloss of 210 or more, an included angle diffuse transmission value of 2.0 or less, and a coefficient of static friction between the slippery layers of 0.3 or more. 1-A, 4 or less.

The polyester used as the substrate film (base film) and slippery layer film of the composite polyester film of the present invention is a crystalline polyester such as polyethylene terephthalate or polyalkylene naphthalate, and polyethylene terephthalate is particularly suitable, although it is not particularly limited. Above all, 80 mol% or more of its repeating units consist of ethylene terephthalate, and in this case, the copolymer components include isophthalic acid, p-
β-oxyethoxybenzoic acid, 2,6-naphthalenecarboxylic acid, 4,4'-dicarboxyldiphenyl, 4
．． 4'-dicarboxylbenzophenone, bis(4-
dicarboxylic acid components such as carboxylphenyl)ethane, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid, cyclohexane-1,4-dicarboxylic acid, propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanedimethanol, bisphenol A Glycol components such as ethylene oxide adducts, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, and oquine carboxylic acid components such as p-oxybenzoic acid can be arbitrarily selected and used. In addition, a small amount of a compound containing an amide bond, urethane bond, ether bond, carbonate bond, etc. may be included as a copolymerization component.

The material for the inorganic and/or organic fine particles contained in the slippery layer is selected from materials that are insoluble in polyester.

Inorganic substances include metal oxides such as silicon dioxide, titanium dioxide, and zirconium dioxide, composite oxides such as kaolinite and zeolite, and salts such as cal/rum sulfate, barium sulfate, calcium carbonate, and calcium phosphate. Examples of the organic substance include silicone resin having a siloxane bond in the main chain, polystyrene, polyacrylic acid, and the like. The above-mentioned 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 0.01% by weight.
03 to 0.08% by weight.

If it is less than 0.01, the slipperiness of the film will be insufficient and workability will decrease. If it exceeds 0.1% by weight, the transparency of the film will decrease.

kll fine particles, preferably the area ratio calculated by formula (I) is 60% or more], more preferably 80%
or more, more preferably 90% or more.

In formula (I), the projected cross-sectional area of the particle and the area of the circle circumscribing the radius can be obtained by observing with a scanning electron microscope. If fine particles having an area ratio of less than 60% with respect to the circumscribed circle are used, the resulting film will have a poor balance between transparency and slipperiness.

Further, it is preferable that the L fine particles have substantially uniform particle size and a particle size distribution close to monodisperse.

Specifically, it is preferable that the degree of dispersion obtained by observation with a scanning electron microscope is 25% or less.

More preferably it is 20% or less. As the variation in particle size increases, the balance between transparency and slipperiness deteriorates.

The slippery layer may further contain various additives. For example, a surfactant or a phosphate is included to prevent IF from aggregating fine particles. Other additives include antistatic agents, colorants, etc.

1- Fine particles and various additives as necessary are mixed with the polyester resin by various methods. For example, a polyester resin and fine particles can be mixed by (1) adding fine particles during the polymerization process of the polyester; or (2) adding fine particles when kneading the polyester in an extruder. For uniform dispersion in the slippery layer, method (2) is preferred.

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 fine particles, it is preferable to disperse the fine particles in an appropriate medium and add the fine particles. The medium is preferably a liquid substance among the constituent components of the polyester to be prepared. The method for dispersing the fine particles in the medium is not particularly limited, and one or a combination of general dispersion methods such as a high-speed stirring method, a homogeneous pressure dispersion method, and a sand mill method may be used. In the method of kneading the fine particles with the resin described in (1), it is also recommended to employ the masterba method or the Sochi method. When the additive is gold-pigmented, it is added together with the fine particles in the method (2), for example.

In the laminated film of the present invention, the easy-sliding layer containing the above particles can be laminated on at least one side of the base film by various methods. For example, (1) the polyester raw material (A) used as the base film and the polyester raw material (B) used as the slippery layer film are separately melted in an extruder or the like at a temperature higher than the melting point, and then There is a method in which extruded and molded unstretched films are laminated together in a heated state: Another method is (1) in which a molten film of one unstretched film is melt-laminated on the surface of the other unstretched film. : Still another method is (3) a method of extruding the laminated state through a die [1] to form an unstretched film using a coextrusion method.

The thus obtained laminated film is stretched in one direction or in the -5 force direction at a temperature of 1-1 or higher than the first-order transition point of the polyester. In the case of -axial stretching, the stretching ratio is small (both 1.5 times the amount 1.1, preferably 3 to 5 times), and in the case of biaxial stretching, the stretching ratio is 2 to 30 times, preferably 9 to 5 times the stretching area. 2
It is 0 times. The biaxial stretching of the film may be carried out sequentially or simultaneously. Furthermore, relaxation and heat treatment are performed if necessary.

(Example) Examples of the present invention will be described below. In Examples and Comparative Examples, all parts are by weight unless otherwise specified. The average particle diameter, degree of dispersion, and area ratio with respect to the circumscribed circle of the fine particles used in the present invention were determined by the following methods (a) and (b). Furthermore, the obtained laminated sheets were evaluated by methods (C) to (e).

(a) Average particle size and variation in particle size of fine particles The fine particles used are photographed using a scanning electron microscope (Hitachi Model S-510), and the photograph is enlarged and copied. Further tracing is performed and images corresponding to 200 particles are randomly filled in black. The Feret diameter in the horizontal direction of this image is measured using an image analyzer (Reco Co., Ltd. Reezex Model 500), and the average value thereof is taken as the average particle diameter. The degree of variation in particle diameter is calculated using the following formula.

(b) Randomly select 20 particles from the trace image used to measure the area ratio average particle diameter with respect to the circumscribed circle, and calculate the projected cross-sectional area of each particle by (
Measure with the image analysis device used in a). The area of a circle circumscribing those particles is calculated, and the area ratio is determined using the f formula.

(c) Transparency of film (1) Haze The haze value is measured according to JIS KG714 using an integrating sphere type haze meter manufactured by Toyo Ti Kiku.

(iil L S I Measure the 17S value (included angle diffuse transmission value) using a visual transparency tester manufactured by Toyo Seiki ■.

(d) Smoothness of the film According to ASTM-D-1894-G3T, 23℃・65
%RH and a tensile speed of 200 mm10+in, the static friction coefficient of the same 7 easy-sliding layer surfaces is measured.

(e) Gloss of film The gloss value at 45° is measured using a gloss meter manufactured by Nippon Heavy Industries, Ltd. according to JIS Z-8741.

Example 1 Two extruders are connected to one T-die, the - extruder contains substantially lubricant-free polyethylene terephthalate (A) (IV; 0.62) for the base layer. The other extruder was charged with 7 liters (average particle size 0.7p, degree of dispersion 14%, area f relative to the circumscribed circle 96%) for the easy-slip layer.
Polyethylene terephthalate (B) containing 06% by market weight
(1V; 0.62), melted at a temperature of 285°C, extruded three layers (easy slipping layer / base material layer / easy slipping layer) of laminated resin from a T-shaped die, and rotating cooling roll (25°C) of"
- It was cooled and solidified to form a laminated unstretched sheet. This unstretched sheet was heated to 85° C. and stretched 3.5 times in the sheet traveling direction between two sets of rolls having different rotational speeds. The obtained uniaxially stretched film was fed into a tenter-type horizontal stretching machine, heated to 95° C., and then stretched 3.9 times in the direction perpendicular to “2”. This film was then heated to 3.5
It was treated with hot air at 225° C. while relaxing by 50%, and then wound up. Table 1 shows the properties of the obtained film.

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

Example 4 The same as Example I 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 obtained film was of high quality with excellent transparency, gloss, and slipperiness.

Example 5 The same as Example 1 except that the total thickness of the film in Example 1 was changed as shown in Table 1.

The obtained film was of high quality with excellent transparency and optical iR, and also excellent slipperiness.

Comparative Example 1 This is the same as Example 1 except that the thickness of the slippery layer in Example 1 was changed as shown in Table 1. The quality of the obtained film was poor in transparency and gloss.

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

Comparative Example 3 This is the same as Example 1 except that the amount of fine particles in the slip layer in Example 1 was changed as shown in Table 1.

The quality of the obtained film was poor in slipperiness.

Comparative Example 4 This was the same as Example 1 except that the amount of fine particles in the slip layer was changed as shown in Table 1.

The quality of the obtained film was poor in transparency and gloss.

Comparative Example 5 The same as Example 1 except that the fine particles in the slip layer were changed as shown in Table 1.

The quality of the obtained film was poor in slipperiness.

In addition, when observing these fine particles with a scanning electron microscope, there is a large degree of variation in particle size, and it is difficult to measure the area ratio with respect to the circumscribed circle. The cumulative 50% diameter was 1.8μ. The particles were also observed using a phase contrast microscope (manufactured by Kon), and the area ratio with respect to the circumscribed circle was measured in the same manner as when using a scanning electron microscope, and it was found to be 53%.

(Effects of the invention) As described above, the composite polyester film of the present invention has
It has excellent transparency and slipperiness, exhibits excellent gloss when metal is vapor-deposited, and can be suitably used as a packaging film and various industrial films as a film with excellent workability and processability.

Claims (1)

[Claims] 1. A slippery layer containing 0.01 to 0.1% by weight of inorganic and/or organic fine particles is laminated on at least one side of a polyester film substantially free of fine particulate lubricants. A composite polyester film, in which the area ratio with respect to the circumscribed circle expressed by the following formula (I) obtained by observing the particles with a scanning electron microscope is 60% or more, and 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 slippery layer. Area ratio to circumscribed circle = (projected cross-sectional area of particle) / (area of circle circumscribed to particle) (I)