JPH0657015A - Syndiotactic polystyrenic oriented film - Google Patents

Abstract

PURPOSE:To provide the syndiotactic polystyrenic biaxially oriented film, and more in detail to provide the syndiotactic polystyrenic biaxially oriented film excellent in transparency, excellent in the smoothness of the film surface, and good in handling characteristics without relating to the thickness of the film. CONSTITUTION:The syndiotactic polystyrenic biaxially oriented film is characterized by having the sum of its surface and inner hazes (per 10mu) of 10% or less, a three-dimensional surface roughness SDELTAa of 0.004-0.04 on at least one surface, and an air-passing rate of 900 sec or shorter.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a syndiotactic polystyrene biaxially stretched film, more specifically, excellent transparency, smoothness of the film surface, and good handling characteristics regardless of the film thickness. The present invention relates to a syndiotactic polystyrene biaxially stretched film.

[0002]

2. Description of the Related Art Biaxially stretched syndiotactic polystyrene films are excellent in heat resistance, electrical characteristics, transparency, etc.
It is expected to be applied to various film applications such as magnetic tapes, photo / plate making, capacitors, and packaging. When it is used for these films, it is required that the film surface be smooth and thin, and that it be transparent and not turbid, especially in applications such as photography and plate making. However, in the syndiotactic polystyrene biaxially stretched film, if the film is simply smoothed and made transparent, the handling properties during the production and processing of the film become poor. Also, when a lubricant is added to improve the handling property, internal haze increases due to surface irregularities and voids formed in the gap between the lubricant and the polymer even if the handling property is improved, depending on the lubricant used. , The transparency as a whole is reduced.

As a film having good slipperiness, a film in which inorganic particles are added, the surface roughness Ra is within a specific range, and the coefficient of static friction is limited is known (Japanese Patent Laid-Open No. 3-74437).
issue). Further, a film having excellent transparency using a syndiotactic polystyrene biaxially stretched film is known (JP-A-1-316246, JP-A-1-168709, JP-A-2-2797).
31).

[0004]

However, with the above-described conventional film having good slipperiness, good handling characteristics can be obtained at low speed work, but there is a problem that the handling characteristics rapidly deteriorate at high speed work. . Further, in the syndiotactic polystyrene biaxially stretched film, the handling property tends to deteriorate particularly when the thickness of the film becomes thin, and the above-mentioned inorganic particles are added to define the range of the surface roughness Ra and the coefficient of static friction. The film has the same tendency, and even if good handling characteristics were obtained for that reason, desired handling characteristics could not be obtained when the thickness was changed.
In addition, since the syndiotactic polystyrene biaxially stretched film is large in brittleness, in the stretching process, around the lubricant added to improve the slip property, voids are likely to occur, resulting in poor transparency. was there.

An object of the present invention is to provide a syndiotactic polystyrene type biaxially stretched film which is excellent in transparency and smoothness of the film surface and is excellent in handling property regardless of the film thickness. .

[0006]

According to the present invention, the sum of surface haze and internal haze (10 μm) is 10% or less, the three-dimensional surface roughness S Δa of at least one surface is 0.004 or more and 0.04 or less, and air bleeding is performed. A syndiotactic polystyrene biaxially stretched film with excellent transparency, smoothness of the film surface, and good handling properties regardless of the film thickness, characterized by a speed of 900 seconds or less. It is provided.

The polystyrene polymer having stereoregularity of syndiotactic structure used in the present invention has a tacticity of diad (constituent unit is a phenyl group or a substituted phenyl group which is a side chain) quantified by a nuclear magnetic resonance method. 85% or more for two) and 50 for pentad (5 units)
It is desirable that the structure has a syndiotactic structure of not less than%.

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 polystyrene polymer used in the present invention has a weight average molecular weight of 10,000 or more, more preferably 50,0.
00 or more. When the weight average molecular weight is less than 10,000, it is not possible to obtain a biaxially stretched film having excellent strength and elongation characteristics and heat resistance. The upper limit of the weight average molecular weight is not particularly limited, but if it is 1500,000 or more, breakage may occur due to an increase in stretching tension, which is not preferable.

Further, the syndiotactic polystyrene biaxially stretched film of the present invention can be produced by a known method, for example, a sequential biaxial stretching method in which longitudinal stretching and transverse stretching are carried out in order,
A stretching method such as a transverse / longitudinal / longitudinal stretching method, a longitudinal / lateral / longitudinal stretching method, or a longitudinal / longitudinal / lateral stretching method can be adopted. The syndiotactic polystyrene biaxially stretched film in the present invention may be required to have a film having excellent heat resistance at high temperature, and in that case, in addition to the selection of these stretching methods, the stretching conditions have a great influence. Moreover, in order to obtain excellent heat resistance such that the heat shrinkage rate at 200 ° C. is 5% or less, and further 2% or less, it is preferable to perform heat setting treatment, longitudinal relaxation treatment, transverse relaxation treatment, or the like. . The haze, the three-dimensional surface roughness SΔa, and the air bleeding speed are adjusted by the film forming conditions and the lubricant particles. The type and amount of the lubricant particles are not particularly limited as long as the haze, the three-dimensional surface roughness SΔa and the air bleeding speed are within the predetermined ranges, but silica, titanium dioxide, talc,
Examples are particles that are inert to syndiotactic polystyrene-based polymers, such as metal oxides such as kaolinite, salts of metals such as calcium carbonate, calcium phosphate, and barium sulfate, or particles consisting of organic polymers. Any one of these lubricants may be used alone, or two or more thereof may be used in combination, but the average particle size of the lubricant used is 0.01 μm or more and 2.0 μm or less, particularly 0.05 μm.
Or more and 1.5 μm or less, and the degree of variation in particle size (ratio of standard deviation and average particle size) is preferably 25% or less. % Or less, especially 0.1% to 1.0% by weight
The following are preferred. In addition, it is preferable that the shape of the lubricant particles includes at least one kind having a surface shape factor of 60% or more. This area shape factor is calculated by the following equation. Area shape factor = (projected cross-sectional area of particle / area of circle circumscribing particle) x 100 (%)

The polystyrene-based polymer used in the present invention may contain, if necessary, known compounds such as antioxidants and antistatic agents in suitable amounts. The blending amount is
10% by weight or less is desirable based on 100% by weight of the polystyrene polymer. If it exceeds 10% by weight, breakage tends to occur during stretching, resulting in poor production stability. The sum of the surface haze and the internal haze (per 10 μm) of the syndiotactic polystyrene type biaxially stretched film in the present invention needs to be 10% or less. It is preferably 7% or less, more preferably 5% or less. Particularly in photolithography applications, it is not preferable that the surface haze and the internal haze (per 10 μm) exceed 10%. The surface haze is preferably 4% or less.

Further, the syndiotactic polystyrene biaxially stretched film of the present invention must have a three-dimensional surface roughness SΔa of at least one surface within a range of 0.004 to 0.04. When SΔa is less than 0.004, handling characteristics are poor, and when it exceeds 0.04, electromagnetic conversion characteristics are poor in, for example, magnetic tape applications, and transparency is reduced in photographic and plate making applications. Causes the problem of a decrease in Further, the syndiotactic polystyrene biaxially stretched film of the present invention needs to have an air bleeding speed of 900 seconds or less. More preferably, it is 700 seconds or less. That is, the air release rate is 900
By setting the time to not more than 2 seconds, more preferably not more than 700 seconds, it is possible to obtain a syndiotactic polystyrene biaxially stretched film having good handling properties regardless of the thickness and strength of the film even during high-speed working. Conversely,
If the air bleeding speed exceeds 900 seconds, the handling characteristics during high-speed work will be poor, and for example, when film is wound into a roll at high speed, air is easily trapped between the film and the take-up roll, and wrinkles easily occur. The winding shape becomes poor, and the film winds in the width direction due to the lubricating effect of the air layer in which the film is wound, and the end face of the roll becomes uneven.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition,
The evaluation method of the film is shown below. (1) Film haze According to JIS-K6714, the surface haze and the internal haze were determined by a Poic integrating sphere type HTR meter SEP-H2D type manufactured by Japan Precision Optical Co., Ltd. (2) Three-dimensional surface roughness SΔa Using a stylus-type three-dimensional surface roughness meter (SE-3AK, Kosaka Laboratory Ltd.) on the film surface, needle radius 2 μm, load
Cutoff value of 0 in the longitudinal direction of the film under the condition of 30 mg.
25 mm, measuring length 1 mm, 2 μm pitch
It is divided into 500 points and the height of each point is calculated by 3D roughness analyzer (SP
A-11). The same operation as above was continuously performed 150 times in the width direction of the film at intervals of 2 μm, that is, over 0.3 mm in the width direction of the film, and the data was taken into the analyzer. Next, SΔa was obtained using an analyzer. (3) Venting speed The measuring device shown in FIG. 1 is prepared. That is, a circular hole 1a is provided on the upper surface of the base 1, a glass plate 2 having a diameter of 70 mm is fixed in the hole 1a, and the glass plate 2 is fixed between the outer periphery of the glass plate 2 and the hole wall 1b. A groove is formed, and a ring-shaped groove 1c surrounding the hole 1b is opened, the groove 1c is communicated with the groove on the outer periphery of the glass flat plate 2, and the vacuum pump 4 is inserted through the pipe 3 into the groove 1c. Connect the suction port of. Then, a film sample 5 having a size that covers the glass flat plate 2 is placed on the upper surface of the base 1, and the outer periphery of the film sample 5 is hermetically fixed to the base 1 with an adhesive tape 6, and the vacuum pump 4 is driven to drive the glass flat plate. The time (seconds) from the appearance of the interference fringes on the outer peripheral portion of 2 to the spread of the interference fringes on the entire surface of the glass flat plate 2 and the movement thereof is measured, and this time (second) is defined as the air bleeding speed.

(4) Film handling characteristics When slitting a wide slit roll at a high speed and rewinding it into a narrow roll, is it possible to obtain a roll without problems such as misalignment of the end of the roll, wrinkles and valves? Please 4
It was graded and evaluated according to the following ranking. 1st grade: It is extremely difficult to obtain a problem-free slit roll 2nd grade: A low-problem slit roll can be obtained 3rd grade: A medium-speed slit roll can be obtained 4th grade: A high-speed nonproblem slit Rolls can be obtained (5) Average particle size Lubricant particles are observed with Hitachi Ltd. S-510 scanning electron microscope, photographed ones are magnified and copied, and the external shape of the lubricant is traced 200 particles were painted black. This image was measured for the Feret diameter in the horizontal direction of each particle using a Luzex 500 type image analyzer manufactured by Nikole Co., Ltd., and the average value was taken as the average particle diameter. Also,
The degree of variation in particle size was calculated by the following formula. Variability = (standard deviation of particle size / average particle size) x 100
(%)

(6) Area Shape Factor 20 projected particles are arbitrarily selected from the trace image used for measuring the average particle diameter, and the projected cross-sectional area of each particle is measured using the image analysis device used in (5). did. Further, the area of the circle circumscribing these particles was calculated and calculated by the following formula. Area shape factor = (projected cross-sectional area of particle / area of circle circumscribing particle) x 100 (%) Example Syndiotactic silica with an average particle diameter of 0.8 µm, a variation of 20% and an area shape factor of 70% was used as a lubricant. Tic polystyrene (weight average molecular weight 300000) 3.0 per 100% by weight
After mixing the polymer chip added with the weight% and the polymer chip not added with the lubricant in a weight ratio of 1: 9, dried, melted at 295 ° C., and extruded from a T die with a 200 μm lip gap, It adhered to a 40 ° C chill roll by electrostatic loading and was cooled and solidified to obtain a 75 μm amorphous sheet. The amorphous sheet is first preheated to 80 ° C. by a roll,
Using 5 infrared heaters with a surface temperature of 750 ℃, further heat, and stretch the film 3.8 times in the machine direction at a film temperature of 132 ℃, then preheat the film to 120 ℃ with a tenter, and stretch temperature 120 ℃ in the transverse direction. The sample was stretched 3.3 times at 260 ° C. and heat-set at 260 ° C. The thickness of the obtained film was 6 μm.

Comparative Example The extrusion speed was changed so that the thickness of the amorphous sheet was 60 μm.
In the longitudinal stretching, the same operation as in the example was carried out except that the film temperature was heated to 100 ° C. by a metal roll and the film was stretched 3.0 times.

[0018]

[Table 1]

[0019]

As described above, according to the present invention, by adopting the constitution as set forth in the claims, the transparency is excellent and the smoothness of the film surface is excellent, and further, regardless of the film thickness. A syndiotactic polystyrene-based biaxially stretched film having excellent handling properties is provided, and therefore the industrial value of the present invention is great.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an apparatus for measuring an air escape rate according to the present invention.

[Explanation of symbols]

 1: Platform 2 Glass flat plate 3 Suction pipe 4 Vacuum pump 5 Film sample 6 Adhesive tape

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location B29L 7:00 4F (72) Inventor Tadashi Okuhira 2-1-1 Katata, Otsu, Shiga Prefecture Toyobo Co., Ltd. Research Institute, Inc.

Claims (1)

[Claims] 1. Surface haze and internal haze (per 10μ)
Is 10% or less, the three-dimensional surface roughness S Δa of at least one surface is 0.004 or more and 0.04 or less, and the air bleeding speed is 900 seconds or less, a syndiotactic polystyrene stretched film .