JPH0732470A - Polystyrene oriented film - Google Patents

Abstract

PURPOSE:To obtain a syndiotactic polystyrene oriented film with excellent transparency and a fine handling property irrespective of the thickness of the film, and also having good traveling and cut-resisting properties. CONSTITUTION:The oriented film is such that it consists of styrene polymer practically having a syndiotactic structure, and a three-dimensional facial roughness SRa at least of one face and a PCC value of the number of projections per unit area in the central face of the roughness satisfy a relation of PCC value <=15000XSRa+1500, and the speed of air extraction is 900 sec or lower.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a syndiotactic polystyrene stretched film, and more specifically, a syndetic film having excellent transparency, excellent handling property regardless of the film thickness, and good running property and abrasion resistance. The present invention relates to a stretched tactic polystyrene film.

[0002]

2. Description of the Related Art Stretched syndiotactic polystyrene films have excellent heat resistance, electrical properties, transparency, etc., and are used in various film applications such as magnetic tapes, photo / plate making, labels, capacitors, and packaging. Is expected. When used for these films, its runnability,
The abrasion resistance is a major factor that determines the workability of the film manufacturing process and the processing process in each application, and further determines the product quality. On the other hand, demands for higher transparency and thinner films are increasing. However, in the syndiotactic polystyrene stretched film,
When adding an additive in order to improve the handling characteristics at the time of manufacturing and processing of the film, the traveling property in contact with a guide roll or the like during traveling of the film, and the abrasion resistance of causing scratches on the film surface. However, when the transparency was lowered and the film thickness was further reduced, these improving effects were not sufficient. As a film having good slipperiness, it is known that inorganic particles are added, the surface roughness Ra is in a specific range, and the coefficient of static friction is limited (JP-A-3-74437).

[0003]

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-based 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,
The film having the surface roughness Ra and the range of the coefficient of static friction also has the same tendency, and therefore, even if good handling characteristics were obtained, the desired handling characteristics could not be obtained when the thickness was changed. . Further, the film containing these inorganic particles has a problem that the transparency is lowered. Further, the syndiotactic polystyrene-based stretched film is brittle, and scratches easily occur on the film surface due to friction with a roll or the like during the production and processing of the film, and there is a problem in abrasion resistance. The present invention relates to a syndiotactic polystyrene stretched film which is excellent in transparency and handling property regardless of film thickness, and further has good running property and abrasion resistance.

[0004]

According to the present invention, the three-dimensional surface roughness SRa of at least one side and the number of protrusions PCC per unit area on the center plane of the roughness PCC value satisfy the relation of PCC ≦ 15000 × SRa + 1500. The syndiotactic polystyrene series is excellent in transparency and handling property regardless of the film thickness, and has good running property and abrasion resistance, which is characterized by having an air bleeding speed of 900 seconds or less. A stretched film is provided.

The polystyrene type 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 polymer include polystyrene, poly (p-, m- or o-methylstyrene), poly (2,4-, 2,5-, 3,4- or 3,5-dimethylstyrene. ), Poly (p-tertiarybutylstyrene) and other poly (alkylstyrenes), poly (p-, m- or o-chlorostyrene), poly (p-, m- or o-bromostyrene), poly (p -, M- or
Poly (halogenated styrene) such as 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. Alkoxystyrene), poly (p-, m- or o-carboxymethylstyrene), etc. Poly (carboxyalkylstyrene) Poly (p-vinylbenzylpropyl ether)
And the like, poly (alkylsilylstyrene) such as poly (p-trimethylsilylstyrene), and poly (vinylbenzyldimethoxyphosphite).

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. If the weight average molecular weight is less than 10,000, it is not possible to obtain a 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, it is not preferable because breakage occurs due to an increase in stretching tension.

Further, the syndiotactic polystyrene type stretched film of the present invention can be produced by a known method, for example, a uniaxial stretching method in which longitudinal stretching or transverse stretching is performed, a sequential stretching method in which longitudinal stretching and transverse stretching are sequentially performed, and A stretching method such as a longitudinal / longitudinal stretching method, a longitudinal / lateral / longitudinal stretching method, a longitudinal / longitudinal / lateral stretching method can be adopted, and is selected according to various characteristics such as required strength and dimensional stability. . In addition, you may perform a heat fixation process, a longitudinal relaxation process, a lateral relaxation process etc. as needed. The three-dimensional surface roughness SRa, the number PCC of protrusions on the center plane of the roughness, and the air bleeding speed are adjusted by the film forming conditions of the film and the lubricant particles. The type and addition amount of the lubricant particles are not particularly limited as long as the three-dimensional surface roughness SRa, the number of protrusions PCC value on the center surface of the roughness, and the air bleeding speed fall within the predetermined ranges. , Titanium dioxide, talc, metal oxides such as kaolinite, salts of metals such as calcium carbonate, calcium phosphate, barium sulfate, or particles made of organic polymers such as crosslinked polystyrene resin, crosslinked acrylic resin, silicone resin, crosslinked polyester resin, etc. Examples of the particles are inert to the syndiotactic polystyrene-based polymer.

Any one of these lubricants may be used alone, or two or more thereof may be used in combination, and 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 is preferable, the degree of variation in particle size (ratio between standard deviation and average particle size) is preferably 25% or less, and the addition amount is 0.005% by weight or more based on 100% by weight of syndiotactic polystyrene polymer. 2.0% by weight
It is preferable to contain below, especially 0.1% by weight or more and 1.0
It is preferably less than or equal to weight%. Moreover, it is preferable that the shape of the lubricant particles includes one or more kinds having an area 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, a known antioxidant, antistatic agent or the like in an appropriate amount. The blending amount is preferably 10% by weight or less with respect to 100% by weight of the polystyrene polymer. If it exceeds 10% by weight, breakage tends to occur during stretching, resulting in poor production stability.

Three-dimensional surface roughness SRa of at least one side of the syndiotactic polystyrene stretched film of the present invention
And the number of protrusions PCC per unit area on the center plane of roughness should satisfy the relation of PCC ≤ 15000 × SRa + 1500. When the PCC value and SRa satisfy this relationship, a film with excellent transparency can be obtained. On the other hand, when the PCC value is larger than this range, the transparency is lowered, which is not preferable. The lower limit of the PCC value is not particularly limited, but if it is less than 500 pieces / mm ² , running property and abrasion resistance may be poor, which is not preferable.
Further, SRa is preferably 0.01 μm or more and 0.1 μm or less. When SRa is 0.01 μm or less, running property and abrasion resistance are likely to be poor. Further, when SRa is 0.1 μm or more, it becomes difficult to obtain a film that satisfies both transparency and running property and abrasion resistance at the same time.

Furthermore, the syndiotactic polystyrene stretched film of the present invention must have an air bleeding speed of 900 seconds or less. More preferably, it is 700 seconds or less. That is, by setting the air bleeding speed to 900 seconds or less, and more preferably 700 seconds or less, a syndiotactic polystyrene-based stretched film having good handling properties regardless of the thickness and strength of the film even during high-speed work can be obtained. can get. On the other hand, if the air bleed speed exceeds 900 seconds, the handling characteristics during high-speed work will be poor, and, for example, when winding the film into a roll at high speed, air will be entrapped between the film and the take-up roll. Easy to get
The winding shape may be poor, or the film may meander in the width direction due to the lubricating effect of the air layer in which the film is wound, resulting in uneven roll end surfaces.

[0014]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The methods for measuring the properties of the polystyrene-based transparent gas barrier films prepared in Examples and Comparative Examples and the inert particles used are shown below.

(1) Three-dimensional surface roughness SRa Using a stylus-type three-dimensional surface roughness meter (SE-3AK, Kosaka Laboratory Ltd.) on the film surface, the radius of the needle is 2 μm and the load is
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
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, using an analyzer, SRa (μ
m) was calculated.

(2) 0.00 from the reference plane having the reference height when calculating the PCC value SRa
The number of protrusions with a height of 625 μm or more per 1 mm2.

(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) Handling characteristics of film When slitting a wide slit roll at a high speed and rewinding it into a small roll, can a roll with no problem be obtained without causing misalignment of the end of the roll, wrinkles, valves and the like? 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 Roll is obtained

(5) Runnability of film The film is formed into a tape slit into a narrow width and rubbed on a metal guide roll to run at high speed for a long time. ,
Each of them was evaluated and ranked in 5 stages as shown below. 1st class; high tension 2nd class; slightly high tension 3rd class; medium tension 4th class; slightly high tension 5th class; small tension

(6) Scratch resistance of film When a tape-shaped roll having a narrow slit in the film is rubbed against a metal guide roll to run, the film surface after rubbing against the guide roll should be kept under a constant supply tension. The degree of scratches that occur is evaluated on a scale of 5 and is represented by the following ranking. 1st grade; very many scratches 2nd grade: many scratches 3rd grade: slight scratches 4th grade: almost no scratches 5th grade: no scratches

(7) Average particle size Lubricant particles were observed with a Hitachi Ltd. S-510 scanning electron microscope, photographed ones were enlarged and copied, and the external shape of the lubricant was traced to an arbitrary 200 The individual 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 10
0 (%)

(8) Area shape factor 20 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 analyzer used in (6). 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 (%)

(9) Light transmittance According to JIS-K6714, the light transmittance was determined by a Poic integrating sphere type HTR meter SEP-H2D manufactured by Japan Precision Optical Co., Ltd.

Example 1 Syndiotactic polystyrene (weight average molecular weight 3000
00) As a lubricant for 100 parts by weight, the degree of variation is 20%,
Average particle size of calcium carbonate with area shape factor 80% 1.0 μ
The polymer chips to which 0.5 parts by weight of the product of m was added and the polymer chips to which the lubricant was not added were mixed at a weight ratio of 1: 9, dried, melted at 310 ° C., and T-die having a lip gap of 1000 μm. It was extruded from the slab and adhered to a 40 ° C cooling roll by the electrostatic loading method and solidified by cooling to obtain a 140 μm amorphous sheet.

First, the amorphous sheet is rolled at 100 ° C.
Preheat, use 3 infrared heaters with a surface temperature of 700 ℃, heat it further, and film length of 135 ℃ in the longitudinal direction 3.
The film was stretched 5 times, then preheated to 120 ° C with a tenter, and then stretched 3.3 times in the transverse direction at a stretching temperature of 120 ° C to 260 ° C.
It was heat set in. The thickness of the obtained film was 12 μm. The evaluation results of the obtained film are shown in the table.

Comparative Examples 1 and 2 As a lubricant, 5.0% by weight of calcium carbonate having an average particle size of 0.5 μm, a degree of variation of 20% and an area shape factor of 80% was added to 100% by weight of syndiotactic polystyrene (weight average molecular weight 300000). The weight ratio of the prepared polymer chips to the polymer chips to which the lubricant was not added was 1: 9 (Comparative Example 1
), 0.2 to 9.8 (Comparative Example 2), mixed, dried, melted at 305 ° C., 1000 μm lip gap T
It was extruded from the die, adhered to a 40 ° C. cooling roll by an electrostatic loading method, and solidified by cooling to obtain a 140 μm amorphous sheet.

First, the amorphous sheet is rolled at 100 ° C.
Preheat, use three infrared heaters with a surface temperature of 700 ℃, further heat, and film length of 135 ℃ 3.
The film was stretched 5 times, then preheated to 120 ℃ with a tenter, and stretched 3.3 times in the transverse direction at a draw temperature of 120 ℃ to 260 ℃.
It was heat set in. The thickness of the obtained film was 12 μm. The evaluation results of the obtained film are shown in the table.

[0028]

As described above, according to the present invention, by adopting the constitution as set forth in the claims, the transparency is excellent, the handling property is excellent regardless of the film thickness, and the running property is further improved. Provided is a syndiotactic polystyrene stretched film having excellent properties and abrasion resistance. Therefore, the industrial value of the present invention is great.

[0029]

[Table 1]

[Brief description of drawings]

FIG. 1 is an apparatus for evaluating the air bleeding speed of the present invention.

FIG. 2 is an apparatus for evaluating slipperiness and wear resistance of the present invention.

[Explanation of symbols]

 1; table 2; glass flat plate 3; suction pipe 4; vacuum pump 5; film sample 6; adhesive tape 7; film 8; capstan 9; tension inspection device 10; metal fixing pin

Claims (1)

[Claims] 1. A styrene-based polymer having a substantially syndiotactic structure, having a three-dimensional surface roughness SRa on at least one side and the number of protrusions per unit area PCC value on the center plane of the roughness PCC ≤15000 × A stretched polystyrene film which satisfies the relationship of SRa + 1500 and has an air bleeding speed of 900 seconds or less.