JP3145174B2 - Method for producing polyethylene-2,6-naphthalate film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to polyethylene-2,6-
The present invention relates to a method for producing a naphthalate film, and more particularly, to a method for producing a polyethylene-2,6-naphthalate film having excellent heat resistance.

[0002]

2. Description of the Related Art In recent years, with the advancement of technology, products have been reduced in size, weight, and performance, and special performance has been required of materials used for the products. For example, a film used for a flexible printed circuit needs to have excellent dimensional stability at a high temperature because a high-temperature solder bath is used.

[0003] Polyethylene-2,6-naphthalate film is easy to mold and relatively excellent in heat resistance, so its application to fields requiring heat resistance has been studied. In some cases, it is still not enough. For example, a biaxially oriented polyethylene-2,6-naphthalate film is heat-treated in multiple stages in a specific temperature range, so that the heat shrinkage at 255 ° C. is 0.6 to 0.5.
A method for obtaining a 9% film is described in JP-B-48-40917.

However, in this method, since the treatment is carried out at a high temperature for a long time, there are many practical limitations, and the heat resistance is still not sufficiently satisfactory.

[0005] In particular, by increasing the temperature of the solder bath, the productivity of the flexible printed circuit can be improved and the production cost can be reduced. Therefore, the higher the heat resistance of the substrate film, the better. .

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing a polyethylene-2,6-naphthalate film having improved heat resistance, in particular, dimensional stability under heat.

[0007]

According to the present invention, a biaxially oriented, heat-set polyethylene-2,6-naphthalate film is irradiated with radiation of 0.1 to 10 MGy, and then irradiated with 250 to 250 MGy.
A method for producing a polyethylene-2,6-naphthalate film, wherein the film is heat-treated at 270 ° C.

In the present invention, the polyethylene-2,6-naphthalate constituting the film contains naphthalenedicarboxylic acid as a main acid component, but a small amount of another dicarboxylic acid component may be copolymerized. Is a main glycol component, but a polymer in which a small amount of another glycol component may be copolymerized. Examples of dicarboxylic acids other than naphthalenedicarboxylic acid include, for example, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, diphenylsulfone dicarboxylic acid, and benzophenone dicarboxylic acid, and aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecane dicarboxylic acid. And alicyclic dicarboxylic acids such as hexahydroterephthalic acid and 1,3-adamantanedicarboxylic acid. Further, as glycol components other than ethylene glycol, for example, 1,3-propanediol, 1,4-butanediol,
1,6-hexanediol, neopentyl glycol,
Examples thereof include 1,4-cyclohexanedimethanol and p-xylylene glycol. Further, a polymer in which additives such as a stabilizer, a colorant, and an antistatic agent are blended may be used.

Such polyethylene-2,6-naphthalate is usually produced by a known method by a melt polymerization method. At this time, additives such as a catalyst can be optionally used as needed.

The intrinsic viscosity of polyethylene-2,6-naphthalate is preferably in the range of 0.50 to 0.90.

In the present invention, the above polyethylene
2,6-Naphthalate is melt-extruded at a melting point of + 70 ° C. and solidified by cooling to obtain a substantially non-oriented polyethylene.
A 2,6-naphthalate film is obtained.

Next, the substantially unoriented polyethylene-2,6-naphthalate film is biaxially oriented and heat-set.

The biaxially oriented stretching is performed, for example, in the longitudinal
The film is stretched 2.5 to 4.0 times at 170 ° C, and then stretched 1 times in the transverse direction.
The film is stretched 2.5 to 4.0 times at 30 to 180 ° C. Heat setting is usually performed under tension at 180-240 ° C.

The biaxially oriented, heat-set polyethylene-2,6-naphthalate film thus obtained is added with 0.1 to 1
Irradiate with 0 MGy radiation. Radiation dose 0.1
If it is less than MGy, the effect of improving heat resistance, which is the object of the present invention, cannot be obtained. On the other hand, when the irradiation amount exceeds 10 MGy,
The film is unsuitable because it loses flexibility and becomes brittle, making it unsuitable especially for flexible printed circuits.

As the radiation, for example, γ from ⁶⁰ Co
A beam, an electron beam, or the like can be used. The irradiation rate is
Although not particularly specified, it is effective to use a high dose rate to obtain a required irradiation dose.

The radiation irradiation temperature is usually from room temperature to 150
C. is appropriate, and when irradiating radiation under heating, it is necessary to select a temperature that does not cause heat shrinkage of the film to be irradiated.

The irradiated film is 250
Heat treatment at ~ 270 ° C. If the heat treatment temperature is outside this range, sufficient heat resistance cannot be obtained.

As the heat treatment method, for example, a method of performing heat treatment for a specific time in a heating element maintained at a specific temperature, a method of sequentially performing heat treatment in a plurality of heating elements having different temperatures from a low temperature to a high temperature, and a temperature gradient. A method in which heat treatment is performed in a heated body attached thereto can be used. Examples of the heating element include a gas bath, a liquid bath, a radiation bath, a hot plate, and a hot roll. As the gas bath, an air bath is preferable, but a heating bath using another gas as a medium may be used.
As the liquid bath, a medium of silicon oil, molten salt, molten metal, or other organic / inorganic compound can be used. The hot plate and the hot roll may be used alone or in combination.

The polyethylene-2,6-naphthalate film obtained by the method of the present invention has its melting point disappeared by a crosslinking reaction, and its heat-resistant dimensional stability is improved, so that its heat resistance is remarkably improved. Therefore, it can be suitably used in fields where heat resistance is required, such as flexible printed circuits, for example, electrical insulation applications, transparent conductive applications, and the like.

[0020]

The present invention will be described below in more detail with reference to examples. In addition, the Young's modulus and the heat shrinkage rate in the examples were measured by the following methods.

(1) Young's Modulus The film was cut into a sample having a width of 10 mm and a length of 150 mm, and was pulled at 100 mm between chucks at a pulling speed of 10 mm / min and a chart speed of 500 mm / min using an universal tensile tester of Instron type. The Young's modulus was calculated from the tangent at the rising portion of the obtained load-elongation curve.

(2) Thermal Shrinkage Rate The film sample was immersed in a silicone oil bath at 260 ° C. for 5 seconds to freely shrink, and was calculated from the film length before and after immersion by the following equation.

[0023]

(Equation 1)

[0024]

Examples 1 to 5 and Comparative Examples 1 to 4 Polyethylene-2,6-naphthalate pellets having an intrinsic viscosity of 0.70 were mixed with 17
After drying at 0 ° C. for 4 hours, the mixture was melt-extruded by a conventional method and rapidly cooled to prepare a 620 μm thick non-oriented film. The film was stretched 3.5 times in the longitudinal direction at 140 ° C., and then stretched 3.5 times in the transverse direction at 130 ° C., and then subjected to tension heat setting at 240 ° C. for 30 seconds.

Next, ⁶⁰ Co-γ rays were irradiated at room temperature so as to have the irradiation amount shown in Table 1, and then heat-treated at the temperature shown in Table 1 for 1 hour.

The Young's modulus and the heat shrinkage of the obtained film were as shown in Table 1.

[0027]

[Table 1]

As is clear from the above results, according to the method for producing a polyethylene-2,6-naphthalate film of the present invention, the melting point is high, the heat shrinkage at high temperatures is small, and the heat resistance is excellent. Thus, a polyethylene-2,6-naphthalate film which does not become brittle can be produced.

[0029]

According to the present invention, a heat-resistant polyethylene-2,6-naphthalate film having a high melting point and excellent heat-resistant dimensional stability can be produced.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08J 7/00 C08J 5/18

Claims (1)

(57) [Claims] 1. Biaxially oriented, heat-set polyethylene
0.1 to 10 MGy for 2,6-naphthalate film
A method for producing a polyethylene-2,6-naphthalate film, wherein the film is subjected to a heat treatment at 250 to 270 ° C. after irradiating the film.