JP2550746B2 - Polyester resin film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a film, particularly a polyester resin film.

[Conventional technology]

A polyester resin film, particularly a biaxially stretched polyester resin film typified by a polyethylene terephthalate resin film has excellent electrical properties, mechanical properties, thermal properties, processability, and chemical resistance.
It is used as a base film in a wide range of fields such as magnetic tapes, capacitors, packaging materials, photolithography, and electrical insulation materials.

Such a polyester resin film is required to have good transparency and slipperiness in addition to the above-mentioned characteristics.
For example, Japanese Unexamined Patent Publication No. 62-70046 discloses a polyester resin film having good transparency and slipperiness, which is obtained by laminating multiple polyester resin films. In this polyester-based resin film, a film of polyester-based resin satisfying specific physical properties is laminated in multiple layers, and by incorporating fine particles into the polyester-based resin film on the surface layer side, transparency and slipperiness are simultaneously realized. There is.

[Problems to be Solved by the Invention]

The conventional polyester-based resin film has improved slipperiness as compared with the polyester-based resin film containing no fine particles, but its degree is not sufficient, and thus the handling property is poor. Further, it is difficult to continuously form a film for a long time because the film is likely to be broken during film formation.
In addition, scratches are likely to occur due to the added fine particles.

An object of the present invention is to provide a polyester resin film which has good transparency and slipperiness and is less likely to cause breakage or scratches during film formation.

[Means for solving the problem]

The polyester resin film of the present invention has an intrinsic viscosity A
Of a polyester resin film having a plane orientation coefficient a and a polyester resin film having an intrinsic viscosity B including an inorganic particle having an average particle diameter dμm laminated on the substrate layer and having a thickness Tμm. and a film layer of b. And, the polyester resin film of the present invention,
The following conditions are met.

0.5 ≧ BA ≧ 0.02 25 ≧ T / d ≧ 1.5 ba−1 × 10 ⁻³ The average particle diameter d of the inorganic particles is, for example, 0.2 to 1.0 μm.
Is set to The amount of inorganic particles added to the polyester resin film having an intrinsic viscosity B is set to, for example, 1% by weight or less.

*********** Polyester Resin The polyester resin used in the present invention is a polymer containing an ester group obtained by condensation polymerization of a dicarboxylic acid and a diol. Examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, adipic acid, sebacic acid, 2,6-naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, bis-α, β (2-chlorophenoxy) ethane-4,4′-dicarboxylic acid. Examples thereof include aliphatic and aromatic dicarboxylic acids such as succinic acid and oxalic acid. Examples of the diol include ethylene glycol, 1,
4-butanediol, diethylene glycol, polyethylene glycol, neopentyl glycol, cyclohexanedimethanol, polyethylene glycol and the like can be mentioned. Two or more kinds of each of the dicarboxylic acid and the diol may be used. The intrinsic viscosity of such a polyester resin is preferably 0.4 to 2.0 as measured in 25 ° C. o-chlorophenol, and more preferably 0.
5 to 1.0 is preferable.

In the polyester resin used in the present invention, other monomers or polymers may be copolymerized within 10 mol% in addition to the above dicarboxylic acid and diol. Also,
Two or more types of polyester resins may be melt mixed and used.

Incidentally, particularly preferable polyester resins used in the present invention are polyethylene terephthalate, polyethylene-2,6-naphthalate, and polyethylene-α, β.
Bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate.

The polyester resin used in the present invention contains other types of polymers, ultraviolet absorbers, lubricants, pigments, antioxidants, heat stabilizers, antistatic agents, etc. within a range that does not impair the object of the present invention. May be.

Base Material Layer The base material layer forming the polyester resin film of the present invention is formed using the above polyester resin. The thickness of the base material layer is preferably 0.5 to 800 μm, more preferably 2 to 500 μm.

Coating Layer The coating layer constituting the polyester resin film of the present invention is laminated on one side or both sides of the above-mentioned base material layer.
This coating layer is made of the above-mentioned polyester resin as in the base material layer. The thickness T of the coating layer is 0.01-25
μm is desirable, and 0.3 to 3.0 μm is desirable.

Intrinsic viscosity B of polyester resin used for coating layer
Is set to be larger than the intrinsic viscosity A of the polyester resin used for the base material layer. Thus, by using a polyester resin having a higher intrinsic viscosity than the base material layer on the coating layer side, it is possible to reduce breakage during film formation. Further, when the polyester-based resin film is stretched, it is possible to increase the height of the protrusions formed on the coating layer side by the inorganic particles described later, which makes it possible to impart good slipperiness to the film. Become.

In the present invention, the difference between the intrinsic viscosity A and the intrinsic viscosity B (B
-A) is set in the range of 0.02 to 0.5. When the difference in intrinsic viscosity is less than 0.02, the height of the protrusion cannot be sufficiently increased during stretching of the film, and the slipperiness of the film is reduced. On the other hand, if it exceeds 0.5, the height of the protrusions becomes too high when the film is stretched,
Scratches are likely to occur during film formation.

The polyester resin forming the coating layer contains inorganic particles. Protrusions formed by the inorganic particles are formed in the coating layer, and thus the polyester resin film is provided with slipperiness. The inorganic particles include, for example, lithium fluoride, kaolin, clay, calcium carbonate, silicon oxide, aluminum oxide, calcium phosphate, titanium oxide, etc. in the periodic table of elements of Group I, Group II, Group III, IV.
Inert particles made of a salt or oxide containing a metal element selected from the group and others are used. In addition, a metal compound catalyst, such as an alkali metal compound or an alkaline earth metal compound, used in the production of amorphous silica particles or a polyester resin may be used. These inorganic particles may be used alone or in combination of two or more kinds.

As the inorganic particles, those having an average particle diameter d in a ratio T / d with the thickness T of the coating layer described above in a range of 1.5 or more and 25 or less are used.
When the T / d value is less than 1.5, unevenness in protrusions is likely to occur on the coating layer. On the other hand, when it exceeds 25, the transparency of the coating layer is lowered. The average particle diameter d of the inorganic particles is preferably 0.2 to 1.0 μm, more preferably 0.25 to 0.7 μm. d is 0.2 μm
If it is less than the range, the slipperiness of the polyester resin film may not be sufficient. On the other hand, when d exceeds 1.0 μm, scratches are likely to occur during film formation. The average particle diameter d of the inorganic particles can be determined by the weight average method using the sedimentation method.

The addition amount of the inorganic particles is preferably 1% by weight or less of the polyester resin forming the coating layer. If the amount added exceeds 1% by weight, the transparency of the film may be reduced.

If necessary, organic particles may be added to the polyester resin within a range not exceeding the addition amount of the inorganic particles.

In the present invention, the plane orientation coefficient b of the coating layer is set to be larger than the plane orientation coefficient a of the base material layer. According to this, the stretchability of the film on the coating layer side at the time of stretching of the film is good, and the height of the protrusion due to the inorganic particles in the coating layer can be increased to further improve the slipperiness. In addition, breakage during film formation becomes more difficult to occur.

In the present invention, the difference between the plane orientation coefficient b and the plane orientation coefficient a (b
-A) is set to 1 × 10 ^-3 or more. If the difference in plane orientation coefficient is less than 1 × 10 ⁻³ , the film forming process becomes unstable. The surface orientation coefficient (b) of the coating layer was determined by using methylene iodide as a mount solution and using an Atsube refractometer to measure the refractive index n _{MD in} the length direction (MD direction) and the refraction index in the width direction (TD direction). The rate n _TD and can be measured and found by | n _MD −n _TD |.
On the other hand, the surface orientation coefficient of the base material layer can be measured as follows. First, the birefringence (R
a) is measured. Moreover, the thickness (T + Tb) of the composite film is measured using a dial gage, and the thickness (Tb) of the base material layer is further measured from a cross-sectional photograph of the composite film. Then, the plane orientation coefficient (a) can be known from the obtained data by the following formula.

Method for Manufacturing Polyester Resin Film First, a polyester resin A for a base material layer and a polyester resin B for a coating layer, which satisfy the above physical properties, are prepared. Inorganic particles are previously added to the polyester resin B for the coating layer by a method such as a dry blending method or an addition method during polymerization.

Next, a polyester resin having an intrinsic viscosity A and an intrinsic viscosity B
And the polyester resin B are dried under predetermined conditions and then supplied to separate extruders. Then, both resins are laminated by the co-extrusion method, cooled and solidified on the casting drum to manufacture a polyester resin film in which the films of the above polyester resins A and B are laminated. In addition, polyester resin A, B
May be laminated by a method other than the co-extrusion method. For example, they may be laminated in the short tube portion before the mouthpiece of the extruder or in the feed block. Alternatively, they may be laminated inside the die.

Next, the obtained polyester resin film is stretched. The stretching treatment may be performed uniaxially, biaxially or more. The stretching conditions are not particularly limited. However, it is first stretched at 75 to 130 ° C in the uniaxial direction (usually the longitudinal direction) by 2.0 to 9.0 times, and then at 80 to 160 ° C in the perpendicular direction (usually in the transverse direction) at 2.0 to 9.0 times, if necessary. It is desirable to perform heat treatment while relaxing by 0 to 15%. Moreover, you may re-stretch 1.05-1.8 times as needed. Alternatively, after stretching in the uniaxial direction, various coating agents may be applied to the film, dried, and then stretched in the perpendicular direction.

The plane orientation coefficient of the base material layer and the coating layer can be set within the above range by setting the atmosphere during stretching of the film and the roll temperature for stretching to be lower than the preheating temperature of the film. For example, when the film is rapidly placed in a low-temperature atmosphere before stretching the film, the temperature of only the film layer side is lowered, so that the surface orientation coefficient of the film layer becomes higher than that of the substrate layer. As described above, by adjusting the temperature condition during the stretching of the film, it is possible to provide a difference in the plane orientation coefficient between the base material layer and the coating layer.

Utilization of Polyester Resin Film The polyester resin film of the present invention is used, for example, as a packaging material for foods and pharmaceuticals, a transfer film, a projector film, a magnetic tape, an electric insulating material and the like. In particular, since the polyester resin film of the present invention has good transparency, it is used as a film required to have transparency like a film for a projector.

〔The invention's effect〕

The polyester resin film of the present invention includes the above-mentioned base material layer and coating layer. Therefore, according to the present invention, it is possible to realize a polyester resin film which has good slipperiness and transparency and is less likely to be broken or scratched during film formation.

〔Example〕

Examples 1 to 11 and Comparative Examples 2 to 8 Homopolymers of polyethylene terephthalate for base material layers having intrinsic viscosity A shown in the table and silicon dioxide (Si
A homopolymer of polyethylene terephthalate having an intrinsic viscosity B to which O ₂ ) particles were added at the time of polymerization was prepared. It was then dried under reduced pressure for 4 hours homopolymers tip of each polyethylene terephthalate with 5MmH _g under 160 ° C.. The chips are fed to separate extruders at 285 ° C each, and the film from each extruder is laminated by the coextrusion method to 40 ° C.
A polyester resin film composed of a base material layer and a coating layer was produced by cooling and solidifying on the casting drum.

Next, the obtained polyester resin film was preheated at 93 ° C. and then stretched 3.3 times in the machine direction using a stretching roll at 88 ° C. Next, the polyester resin film stretched in the machine direction was preheated to 115 ° C, and the film was stretched in the transverse direction in a 109 ° C atmosphere.
It was stretched 3.5 times. 225 ℃ while giving 6% relaxation
And a biaxially stretched polyester resin film was obtained.

The obtained biaxially stretched polyester resin film was examined for slipperiness, transparency, surface gloss and breakage during film formation.

Comparative Example 1 A homopolymer of polyethylene terephthalate containing SiO _{2 and} having an intrinsic viscosity of 0.80 was prepared and dried under the same conditions as in Example. Then, this homopolymer chip was supplied to an extruder to produce a monoaxial biaxially stretched polyester resin film under the same conditions as in the examples.

The same test as in the example was conducted on the obtained biaxially stretched polyester resin film.

Test Method Breakage The number of breakages of the film that occurred during continuous film formation for 24 hours was measured.

Sliding property was evaluated by measuring the static friction coefficient and the dynamic friction coefficient based on ASTM-D-1894.

Transparency Measured according to ASTM-D-1003.

Surface gloss A vacuum deposition machine is used to form a 250Å-thick aluminum vapor deposition film on the base layer side of a biaxially stretched polyester resin film, and the surface gloss is visually compared with Lumirror # 50T60 (trade name of Toray Industries, Inc.). It was judged by. The evaluation criteria are as follows.

○: Gloss equivalent to # 50T60.

X: Inferior to # 50T60.

Claims (3)

(57) [Claims] 1. A base material layer having a plane orientation coefficient a, which is made of a polyester resin having an intrinsic viscosity A, and a polyester resin having an intrinsic viscosity B, which is loaded on the base material layer and contains inorganic particles having an average particle diameter of d μm. Thickness Tμ
A polyester resin film comprising a coating layer having a surface orientation coefficient b of m and then satisfying the condition 0.5 ≧ BA−0.02 25 ≧ T / d ≧ 1.5 ba−1 × 10 ⁻³ . 2. The average particle diameter d of the inorganic particles is 0.2 to 1.0 μm.
The polyester resin film according to claim 1, which is m. 3. The polyester resin film according to claim 1, wherein the amount of the inorganic particles added to the polyester resin having the intrinsic viscosity B is 1% by weight or less.