JPH0699485A - Syndiotactic polystyrenic biaxially stretched film - Google Patents

Abstract

PURPOSE:To obtain a polystyrenic biaxially stretched film excellent in slitting properties substantially formed from a styrenic polymer having a syndiotactic structure, characterized by that an orientation ratio calculated according to a predetermined formula is 1.6 or more and having specific distribution in the azimuth angle direction of a specific crystallite in wide angle X-ray diffraction. CONSTITUTION:A syndiotactic polystyrenic biaxially stretched film is substantially formed from a styrenic polymer having a syndiotactic structure and the orientation ratio calculated according to formula; orientation ratio = Ax/Ay (wherein Ax is 1222cm<-1> band intensity when the polarizing direction of infrared rays coincides with the lateral direction of the film and Ay is 1222cm<-1> band intensity when the polarizing direction of infrared rays coincides with the longitudinal direction of the film) of the film is 1.6 or more and the distribution in the azimuth angle direction of a crystallite evaluated using a crystal diffraction peak present at 20.6 deg. in wide angle X-ray diffraction is not divided in the vicinity of the max. value and has only one peak.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a biaxially stretched syndiotactic polystyrene film having excellent slitting property, more specifically, it is excellent when used for magnetic tape, photo / plate making, condenser, packaging. The present invention relates to a syndiotactic polystyrene-based biaxially stretched film having excellent slit properties.

[0002]

2. Description of the Related Art Syndiotactic polystyrene biaxially stretched films have been developed that have excellent heat resistance, electrical properties, transparency, etc. (Japanese Patent Laid-Open Nos. 1-110122 and 1-11).
68709, 1-182346, 2-2797.
No. 31, No. 3-74437, No. 3-109453,
3-99828, 3-124427, 3-1
No. 31644), magnetic tapes, photo / plate making, capacitors, packaging, and other various film applications. In recent years, films having excellent slitting properties have been required in the above fields. However, in the conventional syndiotactic polystyrene biaxially stretched film, due to its brittleness, the slit point is not stable at the time of slitting and breaks due to tearing in the width direction, resulting in extremely poor slitting property. This has led to a deterioration in productivity.

[0003]

In the syndiotactic polystyrene biaxially stretched film, due to its brittleness, the slit point is not stable at the time of slitting and fracture occurs due to tearing in the width direction, resulting in slitting. Productivity has deteriorated and productivity has deteriorated. The present invention is
An object is to provide a syndiotactic polystyrene-based biaxially stretched film having excellent slit properties.

[0004]

The present inventors have earnestly studied to develop a syndiotactic polystyrene biaxially stretched film in which the slit point is stable during slitting and the breakage of the film is unlikely to occur, and as a result, the syndiotactic polystyrene was found. The inventors have found that it is possible to satisfy the slit property by making the orientation of the molecular chains and the orientation of the crystallites within a certain range, and have reached the present invention. That is,
In the present invention, the orientation ratio obtained by the following formula is 1.6 or more and the distribution in the azimuth direction of the crystallites evaluated by using the crystal diffraction peak at 20.6 ° in wide angle X-ray diffraction is divided near the maximum value. A biaxially stretched syndiotactic polystyrene film having excellent slitting characteristics, which has only one peak. The polystyrene polymer with stereoregularity having a syndiotactic structure used in the present invention has a tacticity of diad (two constitutional units) in which a side chain phenyl group or substituted phenyl group is quantified by a nuclear magnetic resonance method. It is desirable that the syndiotactic structure is 85% or more, and pentad (5 constitutional units) is 50% or more.

Examples of the polystyrene-based polymer include polystyrene, poly (p-, m- or o-methylstyrene), poly (2,4-, 2,5-, 3,4- or 3,5-dimethylstyrene. ), Poly (alkylstyrene) such as poly (p-tertiarybutylstyrene), poly (p-, m- or o-chlorostyrene),
Poly (halogenated styrene) such as poly (p-, m- or o-bromostyrene), poly (p-, m- or o-fluorostyrene), poly (o-methyl-p-fluorostyrene), poly ( p-, m- or o-chloromethylstyrene) and other poly (halogen-substituted alkylstyrenes), poly (p-, m- or o-methoxystyrene), poly (p-, m- or o-ethoxystyrene), etc. Poly (alkoxystyrene), poly (p-, m-
Or, poly (carboxyalkylstyrene) such as o-carboxymethylstyrene), poly (alkyletherstyrene) such as poly (p-vinylbenzylpropyl), poly (alkylsilylstyrene) such as poly (p-trimethylsilylstyrene), and Examples thereof include poly (vinylbenzyldimethoxyphosphide).

In the present invention, polystyrene is particularly preferable among the polystyrene polymers. Also,
The polystyrene-based polymer having a syndiotactic structure used in the present invention is not necessarily a single compound, and if the syndiotacticity is within the above range, a polystyrene-based polymer having an atactic structure or an isotactic structure is used. It may be a mixture of, a copolymer and a mixture thereof. The biaxially stretched syndiotactic polystyrene of the present invention is obtained by melt-extruding the syndiotactic polystyrene by a conventional method, then sequentially or simultaneously biaxially stretched, and further stretched in the longitudinal direction or the transverse direction as needed, and then 150- 280
It is obtained by heat-setting at a temperature of ° C, and the most important feature is that the molecular orientation and crystal orientation of the film are within a certain range.

The molecular orientation determined by the infrared absorption method is a parameter for evaluating how much the main chains of syndiotactic polystyrene molecular chains are aligned by transconformation as a whole system including a crystal part and an amorphous part. is there. It is shown that the molecular chains are isotropically present as the value approaches 1 and are oriented in the TD direction as the value approaches 0, and are oriented in the MD direction as the value becomes greater than 1. The inventors have found that the molecular orientation determined by this infrared absorption method has a very strong correlation with the stability of the slit point, and when this value is outside the claimed range, the slit point becomes unstable, The number of breaks at the time of slitting increases rapidly, and a film having good slitting properties cannot be obtained. Further, in order to improve the slit property, it is not enough to give the molecular orientation determined by infrared absorption to the above range, and it is necessary to give the crystallite orientation to a certain specific range. In the syndiotactic polystyrene film of the present invention, the distribution curve in the azimuth direction of the crystallite evaluated using the crystal diffraction peak at 20.6 ° in wide-angle X-ray diffraction gives only one peak without splitting near the maximum value. It is necessary. This crystal orientation represents the degree of orientation of the syndiotactic polystyrene crystallite, and the fact that the distribution curve in the azimuth direction gives only one peak without splitting near the maximum value means that the crystallite has an extreme degree in that direction. It is shown that it is oriented to. The inventors have found that the orientation of the crystallite has a close correlation with the stability of the slit point at the time of slitting, particularly the tear in the width direction, and further, the orientation distribution curve is not split near the maximum value. It has been found that the improvement of the tear at such a slit can be achieved by making only one peak.

[0008]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The evaluation method of the film is shown below. (1) Molecular Orientation The molecular orientation of syndiotactic polystyrene molecular chains was measured according to the report that the infrared absorption band at 1222 cm ⁻¹ was due to transconformation. Using a Perkin Elmer infrared spectrophotometer, the inclination of the sample with respect to polarized infrared was changed and the absorption intensity was measured. 1222 cm ^-1 of light,
The absorption intensity when the electric vector of the incident light coincided with the width direction of the film was standardized in the 1182 cm ^-1 band as Ax, and the absorption intensity when it coincided with the longitudinal direction of the film was normalized in the 1182 cm ^-1 band. If the value is Ay, the molecular orientation is defined by Ax / Ay.

(2) Crystal orientation distribution A biaxially stretched film was laminated so as to have a thickness of about 500 μm and used as a sample for X-ray diffraction, which was a sample of an X-ray diffractometer (Rotaflex manufactured by Rigaku Denki KK) Install in the holder. When X-rays are incident perpendicularly to the film surface, θ = 0 °,
When the detector is on the extension of the incident X-ray, 2θ = 0 °. First, the sample is set so that the scanning surface and the width direction of the film are parallel to each other, and this state is set to an azimuth angle χ = 0 °.
In this state, scan 2θ and fix the detector at the maximum position of the crystal diffraction peak seen near 2θ = 20.6 °. In this state, θ is further scanned and θ is fixed when the intensity of the diffraction peak has a maximum value. In this way, the azimuth angle is scanned after the so-called crystal plane is set,
When the azimuth angle dependence of the crystal diffraction peak intensity at this time is recorded, this is called a crystal orientation distribution curve.

(3) Slitting property A slitting device of the shear cutter type (manufactured by Nishimura Seisakusho) was used for slitting, and the slitting property was judged from the number of breaks at that time as follows. However, the operation of the slitter was performed at a line speed of 100 m / min. When operated for 10 minutes Break 0 times Class 1 Break 3 to 1 class 2 Break 9 to 4 times Class 3 break 19 to 10 times Class 4 break 20 times or more Class 5

EXAMPLE As a lubricant, 2.0% by weight of calcium carbonate having an average particle size of 0.8 μm, a degree of variation of 20% and an area shape factor of 75% was added to 100% by weight of syndiotactic polystyrene (weight average molecular weight 300000). Chips and polymer chips to which a lubricant was not added were mixed at a weight ratio of 1: 9, dried, melt-extruded at 295 ° C., cooled and solidified to obtain an amorphous sheet. The amorphous sheet was first stretched 1.6 times in the machine direction at 140 ° C using multiple infrared heaters, then stretched 3.0 times in the transverse direction at 130 ° C by 3.0 times with a tenter, and then again heated to 125 ° C. To draw 2.5 times in the machine direction. This film was heat set at 240 ° C. and then relaxed at 230 ° C. in the width direction by 3%. The obtained film had a molecular orientation of 3.1, and the crystal orientation distribution curve gave only one peak without splitting even near the maximum value as shown in FIG. The slit property of this film is ranked 1
It was class.

COMPARATIVE EXAMPLE 1 The amorphous sheet used in the example was placed in a tenter in the lateral direction 130
Draw 3.2 times at ℃, then draw 3.5 times in the machine direction using a roll heated to 135 ℃. The film was heat set at 250 ° C. and then relaxed at 230 ° C. in the width direction by 3%.
The obtained film had a molecular orientation of 1.8, and the crystal orientation distribution curve was split into two near the maximum value as shown in FIG. The slit property of this film was grade 5.

Comparative Example 2 The amorphous sheet used in the example was first stretched 1.4 times in the machine direction at 140 ° C. by using a plurality of infrared heaters, and then 1
Stretch 2.2 times in the machine direction using a roll heated to 35 ° C. Then, draw it in the tenter transversely at 135 ℃ 3.0 times,
After heat setting at 0 ° C, the mixture was relaxed at 230 ° C in the width direction by 3%. The obtained film had a molecular orientation of 1.4, and the crystal orientation distribution curve gave only one peak without splitting near the maximum value as shown in FIG. The slit property of this film was grade 5.

[0014]

As described above, the present invention is said to be a syndiotactic polystyrene type biaxially stretched film having an extremely excellent slit property by adopting the constitution as described in the claims. be able to.

[Brief description of drawings]

FIG. 1 is a crystal orientation distribution curve of a film obtained in an example.

FIG. 2 is a crystal orientation distribution curve of the film obtained in Comparative Example 1.

FIG. 3 is a crystal orientation distribution curve of the film obtained in Comparative Example 2.

[Explanation of symbols]

 Azimuthal angle: Film azimuth Intensity: Crystal diffraction intensity

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadashi Okuhira 2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo Co., Ltd.

Claims (1)

[Claims] 1. A substantially styrene-based polymer having a syndiotactic structure, which has an orientation ratio of 1.6 or more as determined by the following formula and has a wide-angle X-ray diffraction pattern.
A syndiotactic polystyrene biaxially stretched film characterized in that the distribution of crystallites in the azimuth direction evaluated using the crystal diffraction peak at 20.6 ° does not split near the maximum value and has only one peak. Orientation ratio = Ax / Ay Ax: infrared light polarization direction 1222Cm ^-1 band intensity Ay when matched with the width direction of the film: the infrared light polarization direction when matched with the longitudinal direction of the film 1222Cm ^-1 Band strength