JPH0260728A - Polyester biaxially oriented film - Google Patents

Abstract

PURPOSE:To impart good physical properties and to especially enhance heat resistance by receiving the fine crystal size and degree of surface orientation of polyethylene-2,6-naphthalate or polyester based thereon in specific ranges. CONSTITUTION:Polyethylene-2,6-naphthalate type polyester to be used pref. has a high MW and, concretely, the intrinsic viscosity thereof in a solvent composed of a 1:1 mixture of phenol and tetrachloroethane on a wt. basis at 25 deg.C is 0.5 or more, pref., 0.6 or more. A requiste to the film composed of said polyester is that a fine crystal size and a degree of surface orientation measured by an X-ray diffraction method are respectively 40-100Angstrom and 80% or more. A biaxially oriented film is pref. prepared by a flat method wherein simultaneous biaxial stretching and heat treatment are combined appropriately.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a polyethylene-2,6-naphthalate biaxially oriented polyester film having excellent mechanical properties and dimensional stability.

(Prior Art and Problems to be Solved by the Invention) Polyethylene-2,6-naphthalate polyester has a higher glass transition point and melting point than polyethylene terephthalate polyester, which has been produced in large quantities in the past. is heat resistant.

It is one of the materials that has long been expected to be used in fields where dimensional stability is required. Therefore polyethylene-
Research on 2,6-naphthalate 2-axis oriented films is also active, and is published in Japanese Patent Publications No. 54-945 and Japanese Patent Publication No. 1987-49.
-8415 Publication, Japanese Patent Publication No. 48-40917, Japanese Patent Publication No. 56-19013, Publication No. 3 Japanese Patent Publication No. 56-43877
No. 50-133274, Japanese Patent Application Laid-open No. 1982-133274
Many examples can be cited, such as Japanese Patent Application Laid-open No. 133278 and Japanese Patent Application Laid-open No. 127730/1983. However, 1
The reality is that the balance between mechanical properties such as strength and elongation and dimensional stability has not reached a sufficient level, and improvements are desired.

The present inventors have discovered that polyethylene-2,6-naphthalate-based 2
The present invention has been arrived at as a result of intensive studies aimed at solving these problems in axially oriented films.

(Means for Solving the Problems) The present inventor's investigation revealed that polyethylene
The fine structure of the polymer constituting the 2,6-naphthalate film greatly influences the physical properties of the film, and a film with good physical properties can be obtained when the microcrystal size and degree of plane orientation are within a specific range.

That is, the present invention provides polyethylene-2,6-1-7 tallate or a polyester containing polyethylene-2,6-1-7 tallate as a main component.
Microcrystal size measured by X-ray diffraction method is 40~
The gist of the present invention is a biaxially oriented polyester film characterized by a polyester film having a surface orientation of 100% and a degree of plane orientation of 80% or more.

In the present invention, polyethylene-2,6-naphthalate or a polyester containing it as a main component is a polyester containing ethylene glycol as a glycol component and 2,6-naphthalene dicarboxylic acid as a dicarboxylic acid component, or a polyester containing these components as a main component, and methylene glycol,
1,4-butanediol diethylene glycol, polyethylene glycol propylene glycol, 1,4-
Cyclohexane dimetatool, xylylene glycol,
Glycol components such as 22-bis(β-hydroxyethoxyphenyl)propane bis(β-hydroxyethoxyphenyl)sulfone, acyhinic acid, sebacic acid, terephthalic acid, isophthalic acid L 1,41.5-+t,'
y −+ Dicarboxylic acid components such as 2.5- or 2.7-naphthalene dicarboxylic acid, hydroxycarboxylic acid components such as ε-hydroxycaproic acid, 4-β-hydroxyethoxybenzoic acid, etc. in small amounts (preferably 10 mol% or less) (more preferably 8 mol % or less) is a polyester contained as a copolymer component, and can be produced by a commonly known polycondensation method.

That is, esterification reaction of 2,6-naphthalene dicarboxylic acid or its lower alkyl (usually methyl) ester with ethylene glycol or a combination of esterification reaction and subsequent deglycol reaction (melt method or solid phase method). be synthesized.

(This also applies when introducing copolymerization components.)
As a catalyst, a gold film compound such as zinc, manganese, cobalt antimony, titanium 1 germanium, etc. is used.

The polyethylene-2,6-naphthalate polyester used in the present invention is preferably a polymer imitation, and specifically, has an intrinsic viscosity of 0.5 at 25°C in a mixed solvent of 1/1 equal weight of phenol/tetrachloroethane. More preferably, it is 0.6 or more.

In the film of the present invention, the microcrystal size and degree of plane orientation measured by X-ray diffraction are 40 to 10, respectively.
0 people and 80% or more are required. The microcrystal size is 5che from the half width of the (110) diffraction peak.
The crystal grain size (A
C5), but it needs to be 40 to 100 people. If AC3 is less than 40, the dimensional stability (heat shrinkage characteristics) is poor; if it is more than 100, the film becomes brittle. Also, regarding the degree of nine-plane orientation, the degree of plane orientation = 100 x (180 - half width) /180
However, if the degree of plane orientation is less than 80%, the strength and elongation properties will be poor.

As a method for producing the biaxially oriented film of the present invention, it is preferable to appropriately combine flat simultaneous biaxial stretching and heat treatment. Specifically, an unstretched film made of polyethylene 2,6-naphthalate or a polyester containing polyester as a main component (an unstretched film can be produced by a commonly known melt film forming method. The melting temperature of the polymer is 270 to 32
The temperature is preferably 0°C, and the film-like material discharged from the goo is 3°C.
It is preferable to suppress crystallization as much as possible by rapidly cooling with a casting roller kept at 0°C or lower. ) at a temperature of 130 to 200°C for 1 hour and 0.5 to 100 seconds, with a stretching ratio of 2.5 to 5.0 times in the vertical and horizontal directions, and an area stretching ratio of 8 to 15 times. After being subjected to flat method simultaneous biaxial stretching, the temperature was 180 to 270.
A method of applying fixed length heat treatment for 1 hour to 200 seconds at °C or tension or relaxation heat treatment at ±15% or less is adopted. In general, stretching and heat treatment at high temperatures work to increase the crystallite size, and high-magnification stretching, tension treatment, and low-temperature stretching lead to an increase in the degree of plane orientation.

Additionally, stretching the unstretched film after slightly swelling it with a solvent 1 that has an affinity for polyethylene-2,6-naphthalate, such as phenol or m-cresol, is also effective in controlling the microcrystal size and degree of plane orientation. be.

In order to obtain the biaxially oriented polyester film of the present invention, the fine structure is adjusted by appropriately combining the above conditions.

Although the present invention is mainly directed to polyethylene-2,6-naphthalate or copolyesters having polyethylene-2,6-naphthalate as a main component, other high-molecular compounds and low-molecular compounds such as polyethylene terephthalate, polybutylene, Contains polyesters such as terephthalate, flame retardants such as phosphorus compounds and halogen compounds, antistatic agents such as polyalkylene glycols, slip agents such as silica particles, other antioxidants, ultraviolet absorbers, matting agents, etc. Needless to say, it's fine.

(Example) The present invention will be explained in more detail below with reference to Examples.

Examples 1-5. Comparative Examples 1 to 3 A pellet of polyethylene-2,6-naphthalate (intrinsic viscosity 0.75) was supplied to an extruder type melt extruder, and extruded at 300'C from a T-die with a lip width of 200 mm and a lip spacing of 0, hm. did. The extruded molten film was cooled and solidified with a casting roller kept at 20°C to obtain an unstretched film.Then, it was subjected to simultaneous biaxial stretching (stretching time 20 seconds) using a tenter, and further both vertically and horizontally. After performing a 5% relaxation heat treatment (heat treatment time 20 seconds), it was trimmed to a thickness of 10μ and a width of 3 at a speed of Ion/min.
A stretched film of 00 mm was rolled up. In this operation, the stretching temperature, the stretching ratio in the longitudinal direction of the film (in the direction perpendicular to the MO force direction (TD force direction), and the heat treatment temperature were varied.

Note that the MD force direction stretching ratios are all 3.1 times.

The resulting film was measured for microcrystal size, plane orientation degree 1 strength, and dry heat shrinkage rate at 180°C. The results are shown in Table 1, and it can be seen that films having values within a specific range in terms of microcrystal size and degree of plane orientation exhibit good performance.

(Effects of the Invention) The polyethylene-2,6-naphthalate-based polyester biaxially oriented film of the present invention has good physical properties and is particularly useful as a heat-resistant film.

Patent applicant: Unitika Co., Ltd.

Claims (1)

[Claims] (1) It is made of polyethylene-2,6-naphthalate or a polyester containing it as a main component, and is characterized by having a microcrystal size of 40 to 100 Å and a degree of plane orientation of 80% or more as measured by X-ray diffraction. Biaxially oriented polyester film.