JP3325980B2 - Laminated polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a laminated polyester film, and more particularly to a biaxially oriented laminated polyester film having an antistatic property.

[0002]

2. Description of the Related Art In recent years, a laminated polyester film formed by a co-extrusion method has attracted attention, and has been partially put to practical use in magnetic recording applications and applications requiring easy transparency. Such a laminated film can impart excellent functions, for example, by blending particles only in the surface layer to improve the transparency of the entire film or to change the roughness of the front and back surfaces. In particular, a laminated polyester film having a layer configuration of three or more layers can be preferably used because it has a large degree of freedom in giving various functions to each layer. The laminated film is also required to have antistatic performance, but if a large amount of an antistatic agent is blended only in the surface layer, so-called blooming often adversely affects post-processes. For example, there are floating of a coating liquid or printing ink due to deterioration of compatibility with an easy-adhesion imparting component, or delamination. Further, when a large amount of an antistatic agent is blended in each layer, the mechanical properties of the film often deteriorate, and the film becomes a hazy film, which is economically disadvantageous.

[0003]

Means for Solving the Problems The present inventors have set forth the above-mentioned object.
As a result of intensive studies to achieve the goal, three or more layers
Surface resistivity of outer layer of film, volume of laminated film
If the specific resistance and outer layer thickness are designed within a certain range
Excellent antistatic performance,
Has been found to have little effect on other functions
It was completed. That is, the gist of the present invention is that
Both outer layers with thickness of 0.05 ~ 1.5μm are laminated
Of at least three layers having a volume resistivity of 10
¹²-10 ¹⁷Ω-cm co-extruded laminated polyester film
And the surface resistivity of both outer layers is 10⁹ ~
10¹⁴Ω / □, when the inner layer is made into a film alone
Has a surface resistivity of 10⁷ -10¹³Ω / □ and both outer layers
Surface resistivity of 10^-1-10^-FourCharacteristic of being double
In the biaxially oriented laminated polyester film.

Hereinafter, the present invention will be described in detail. Examples of the polyester in the present invention include polyethylene terephthalate in which at least 80 mol% of the constituent units are ethylene terephthalate, and polyethylene-2,6-, in which at least 80 mol% of the constituent units are ethylene-2,6-naphthalate.
Naphthalate, a poly-polysiloxane in which at least 80 mol% of the structural units are 1,4-cyclohexane dimethylene terephthalate
1,4-cyclohexane dimethylene terephthalate and the like can be mentioned. Other examples include polyethylene isophthalate and polybutylene terephthalate. Examples of the copolymerization component other than the above-mentioned superior components include, for example, diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol, diol components such as polytetramethylene glycol, isophthalic acid,
Dicarboxylic acid components such as 2,7-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, adipic acid, ageleic acid, sebacic acid and ester-forming derivatives such as oxymonocarboxylic acid can be used.
As the polyester, besides a homopolymer or a copolymer, a blend of a small proportion with another resin can be used.

The laminated polyester film of the present invention (hereinafter referred to as a laminated film) has a three-layer structure and is laminated by a co-extrusion method. Specifically, co-extrusion is performed using a co-extrusion laminating apparatus such as a feed block or a multi-manifold die in a state where the polyester forming the inner layer and the polyester forming both outer layers are melted.
Then, after the obtained molten sheet is rapidly cooled to an unshaped unstretched sheet, biaxial orientation and heat treatment are performed according to a conventional method. Usually, the thickness of each layer of the laminated film can be controlled by adjusting the amount of polymer discharged by a gear pump. In the present invention, if necessary, the inner layer may have a layer configuration of two or more layers, that is, four or more layers.

The most important feature of the laminated film of the present invention resides in that the surface resistivity of both outer and inner layers is within a certain range. In order to achieve a high surface specific resistance value, it is usually carried out mainly by blending an antistatic agent into the polyester of the substrate. Specifically, a method in which an antistatic agent is added to a raw material in a polyester production process, and a method in which an antistatic agent or a master batch containing the same is mixed in a raw material resin during film formation are preferably adopted. Examples of the antistatic agent include representative sulfonate and phosphate derivatives of ion conductive compounds.
The most typical examples include metal salts of alkyl sulfonic acids or metal salts of alkyl benzene sulfonic acids. When these are used, it is preferable to use a polyalkylene glycol in combination because the antistatic effect increases.
Further, carbon black, which is a typical electron conductive compound, can also be used.

In the present invention, both outer layers of the laminated film are used.
Has a surface resistivity of 10⁹-10¹⁴Ω / □, good
Preferably 10^Ten-10¹³Ω / □, more preferably,
10 ¹¹-10¹²Ω / □ range. Surface specificity of both outer layers
Resistance value is 10⁹ If less than Ω / □, use a large amount of antistatic agent
So-called blooming occurs due to the
Adversely affect other functions (such as easy adhesion)
You. In addition, the surface resistivity of both outer layers is 10¹⁴Over Ω / □
In other cases, the antistatic effect is weakened and the object of the present invention is achieved
I can't do it. Further, in the present invention, the thickness of the outer layer is
0.05-1.5 μm, preferably 0.05-0.5 μ
m. When the thickness of the outer layer is less than 0.05 μm
Has difficulty in controlling the thickness of the ultra-thin film. Also, the thickness of the outer layer
If the thickness exceeds 1.5 μm, the conductivity to the adjacent inner layer deteriorates.
And the half-life is delayed. That is, the outer layer is the adjacent inner layer
Bleed-out of ionic conductive compound (strong antistatic layer)
And release the charged charge directly to the outside
Conduction that escapes through the conductive circuit and the inner layer (strong antistatic layer)
Electric circuits, and those that act as a combination of both
This is the greatest feature of the present invention.

In the present invention, the inner layer of the laminated film is formed into a single film (under the same conditions as the production of the laminated film).
The surface resistivity (hereinafter, simply referred to as the surface resistivity of the inner layer) is 10 ⁷ -10 ¹³ Ω / □, preferably 10 ⁸ -10 ¹¹ Ω / □, and more preferably 10 ⁹ Ω / □.
The range is from 10 to 10 ¹¹ Ω / □. When the surface specific resistance value of the inner layer is less than 10 ⁷ Ω / □, the mechanical and thermal strength of the film is reduced by adding a large amount of an antistatic agent. Also,
When the surface specific resistance of the inner layer exceeds 10 ¹³ Ω / □,
The antistatic effect is weakened, which is not practical. Furthermore, the surface resistivity of the inner layer is 10 ⁻¹ to 10 of the surface resistivity of the outer layer.
^-4 times, preferably 10 ^-1 to 10 ^-3 times. If the surface resistivity of the inner layer is less than 10 ^-1 times that of the outer layer, the mechanical and thermal strength of the film is often impaired. In addition, the surface resistivity of the inner layer is 10 ^-4 of that of the outer layer.
If it exceeds twice, the antistatic effect is often lost. When a large number of inner layers are present, the surface resistivity when blended to form a single film is defined as the surface resistivity of the inner layer.

In the present invention, the laminated film has a volume resistivity of 10 ¹² to 10 ¹⁷ Ω-cm, preferably
10 ¹³ to 10 ¹⁶ Ω-cm, more preferably 10 ¹⁴ to 1
The range is 0 ¹⁵ Ω-cm. When the volume resistivity of the laminated film is less than 10 ¹² Ω-cm, the mechanical and thermal strength of the film is reduced by adding a large amount of an antistatic agent. If the volume resistivity of the laminated film exceeds 10 ¹⁷ Ω-cm, the half-life is delayed and the antistatic effect is weakened.

[0010] The laminated film of the present invention may contain additional particles, precipitated particles, other catalyst residues, and the like as a function other than antistatic, for example, as a projection-forming agent for imparting a lubricating property. Furthermore, if necessary, a stabilizer, a lubricant, a cross-linking agent, an anti-blocking agent, an antioxidant, an infrared absorber, a coloring agent, and the like may be contained. These additives are
As long as it does not exceed the gist of the present invention, it may be contained in either the inner layer or the outer layer. The laminated film of the present invention takes advantage of its excellent properties, in the magnetic recording field such as video tape, audio tape, floppy disk, and magnetic card, for photography, microfilm, plate making, and in the field of graphic arts such as tracing film, , Packaging materials, displays, building materials and the like.

[0011]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. In the examples and comparative examples, “parts” and “%” mean “parts by weight” and “% by weight”, respectively. The method for measuring physical properties (characteristics) and the raw material polyester are as follows. (1) Surface specific resistance Yokogawa and Hewlett-Packard's concentric electrodes "16
008A (trade name) (50 mm diameter inner electrode, 70 mm outer electrode), place the sample in an atmosphere of 23 ° C. and 50% RH, apply a voltage of 100 V, and after 60 seconds, use the high resistance meter “ 4329A (trade name) ". (2) Volume specific resistance Yokogawa Hewlett-Packard's concentric electrode "16
008A (trade name) (50 mm diameter inside electrode, 70 mm diameter outside electrode), place the sample in an atmosphere of 23 ° C. and 50% RH, apply a voltage of 100 V, and after 60 seconds, use the high resistance meter “ 4329A (trade name) ", the volume resistivity of the sample was measured.

(3) Half-life A static honest meter (H-
0110 type) with a constant temperature and humidity chamber (PR-2)
G type) and measured the half-life of the sample in an atmosphere of 23 ° C. and 50% RH.

(4) Running Stability A film having a width of 12.5 mm was subjected to a tension of 100 g, and the film was reciprocated 100 times between plastic pins. （(Good): no turbulence at all △ (normal): edges are slightly irregular X (poor): edges are irregular

(5) Durability The process of wiping the film surface with ethanol-soaked gauze and air-drying is repeated 5 times, and then measuring the film surface specific resistance value. In comparison with the values, the change in the surface resistivity was evaluated in the following three ranks. ○ (Good): Surface resistivity (Ω / □) increased by less than one digit △ (Normal): Surface resistivity (Ω / □) increased by one digit or more and less than two digits × (Bad): Surface resistivity Value (Ω / □) increases by more than two digits

(6) Wetting index According to JIS-K6768-1977, a reagent is applied to the surface of a sample film using a wetting index reagent (manufactured by Wako Pure Chemical Industries, Ltd.), and is evaluated according to the following three ranks according to wettability. did. （(Good): 50 (dyne / cm) or more △ (normal): 49 (dyne / cm) or less 40 (dyn)
e / cm) x (bad): 39 (dyne / cm) or less

(7) Surface roughness: Determined as follows using a surface roughness measuring instrument (SE-3F) manufactured by Kosaka Laboratory Co., Ltd. That is, a portion having a reference length L (2.55 mm) is extracted from the film cross-sectional curve in the center line direction, and the center line of the extracted portion is the x-axis, and the direction of the vertical magnification is the y-axis, and the roughness curve y = f ( x), the value given by the following equation was measured at 10 points, and the average value was defined as Ra. In addition,
The tip radius of the stylus was 2 μm, the load was 30 mg, and the cutoff value was 0.08 mm.

[Number 1] Ra = (1 / L) ∫ 0 L | f (x) | dx

The raw material polyesters used in the examples and comparative examples are as follows. <Raw material polyester> (1) Polyester A 0.2% by weight of spherical silica having an average particle size of 0.5 μm, an antistatic agent (Nikko Petrochemical Co., trade name: Atrai AS103)
Polyethylene terephthalate containing 0.4% by weight of 0) and 1.0% by weight of polyethylene glycol having a molecular weight of 6000. (2) Polyester B antistatic agent (Nikko Petrochemical Co., trade name: Atrai AS1)
(3) Polyester C 0.1% by weight of kaolin particles having an average particle diameter of 0.6 μm, 0.4% by weight of sodium dodecylsulfonate, and a molecular weight of 6
(4) Polyester D Polyethylene terephthalate containing 0.2% by weight of spherical silica having an average particle size of 0.5 μm

Example 1 Polyesters A and B were laminated in a die so as to have an A / B / A layer structure, extruded in a sheet form from a die at 290 ° C., and quenched on a cooling drum. A non-oriented sheet having a three-layer structure was obtained. The obtained non-oriented sheet is stretched 3.7 times at 85 ° C in the length direction and 4.0 times at 95 ° C in the width direction, and then heat-treated at 230 ° C for 2 seconds to obtain a biaxially oriented laminated polyester film. I got The obtained laminated film is
It had a thickness of 0.1 μm / 14.5 μm / 0.1 μm. The measurement results of the physical properties and properties of the laminated film are shown in Table 1 below. The laminated film shows good antistatic properties and has a surface wetting index of 54.
(Dyne / cm) and a preferable laminated film showing good adhesiveness.

Example 2 In Example 1, the thickness was changed in the same manner as in Example 1 except that polyesters A, B and C were used and laminated in a die so as to have an A / B / C layer structure. Configuration 0.1μm
A biaxially oriented laminated polyester film having a three-layer structure of /14.5 µm / 0.1 µm was obtained. The measurement results of the physical properties and properties of the obtained laminated film are shown in Table 1. The laminated film showed a good antistatic property, and was a useful laminated film having characteristics in which the front and back surfaces had different roughnesses. .

Example 3 Example 1 was the same as Example 1 except that after stretching in the length direction, an in-line coating was performed on one surface to improve the adhesion to printing ink and the like. Thus, a biaxially oriented laminated polyester film having a five-layer structure having an easily adhesive coating film on one surface was obtained. The in-line coating coat is a 10% by weight aqueous dispersion of “Finetex ES-650” (trade name) manufactured by Dainippon Ink and Chemicals, Inc. and “Impranyl DL11” (trade name) manufactured by Bayer AG in a 20:80 weight ratio. The liquid was used and the thickness after drying was 0.03 μm. Even when the laminated film was run with the in-line coating-coated surface as the contact surface, the increase in the chargeability was small, and the laminated film was an excellent laminated film.

Comparative Example 1 A single-layer biaxially oriented polyester film having a thickness of 15 μm was obtained in the same manner as in Example 1 except that only polyester B was used. The measurement results of the physical properties and properties of the obtained film are shown in Table 2 below. Although the film was excellent in antistatic properties, many traces of bleed out of the antistatic agent were observed on the film surface, and the film was applied. There were concerns that other functions could be adversely affected and were not satisfactory.

Comparative Example 2 In Example 1, polyesters B and D were used,
D / B / D (0.1 μm) was obtained in the same manner as in Example 1 except that the layers were stacked in a die so as to have a D / B / D layer configuration.
/14.5 μm / 0.1 μm) to obtain a biaxially oriented polyester film having a three-layer structure. Table 2 shows the measurement results of the physical properties and characteristics of the obtained film. The film had high chargeability and was difficult to use.

Comparative Example 3 In Example 1, polyesters A and D were used,
A / D / A (0.1 μm) was obtained in the same manner as in Example 1 except that the layers were laminated in a die so as to have an A / D / A layer configuration.
/14.5 μm / 0.1 μm) to obtain a biaxially oriented polyester film having a three-layer structure. The measurement results of the physical properties and properties of the obtained film are shown in Table 2. Although the film has no problem in wettability, the A / B of Example 2 was used.
Compared with / A, the volume resistivity of the laminated film was higher, and the running was unstable during running, especially when repeatedly running.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

According to the present invention, there is provided a laminated film provided with an antistatic property without impairing the mechanical properties of the film and without adversely affecting other functions to be provided. It can be suitably used in applications, graphic arts and packaging materials, and its industrial value is high.

Continuation of the front page (56) References JP-A-7-89026 (JP, A) JP-A-3-121137 (JP, A) JP-A-3-44636 (JP, A) JP-A-60-115022 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 1/00-35/00

Claims (1)

(57) [Claims] 1. The inner layer has a thickness of 0.05 to 1.5 each.
A body comprising at least three layers in which both outer layers of μm are laminated.
Product specific resistance value is 10¹²-10¹⁷Ω-cm co-extruded laminate
The surface resistivity of both outer layers of a polyester film
Is 10 ⁹ -10¹⁴Ω / □, inner layer alone
Surface specific resistance value of 10 when formed into a film⁷ -10¹³
Ω / □ and 10 of the surface resistivity of both outer layers^-1-10^-Four
Biaxially oriented laminated polyester film
Film.