JPH07117187A - Polystyrene laminated film - Google Patents

Abstract

PURPOSE:To obtain a syndiotactic polystyrene laminated film, and more precisely, a syndiotactic polystyrene laminated film that is suitably used for a base film for wrapping, capacitor, and magnetic tapes, having a good transparency and handling property irrespective of the thickness of the film, and further having a sliding property and abrasion resistance. CONSTITUTION:A surface layer containing no fine particles is formed on at least one surface of the film made of styrene polymer having a syndiotactic structure, and the relation between a three-dimensional surface roughness SRa on the surface layer and a PCC value of the number of projections per unit area in the central surface of roughness meets a formula of 15,000XSRa+500<=PCC<=15,000XSRa+3500, and the permeability to air is 900sec. or lower.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a syndiotactic polystyrene-based laminated film, more specifically for packaging,
The present invention relates to a syndiotactic polystyrene-based laminated film, which is suitable as a base film for capacitors and magnetic tapes, has excellent transparency, has excellent handleability regardless of the film thickness, and has excellent slipperiness and abrasion resistance. Is.

[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. Furthermore, 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. It is an object of the present invention to provide a syndiotactic polystyrene-based film which is excellent in transparency and handling property regardless of the film thickness, and which is good in running property and abrasion resistance.

[0004]

According to the present invention, a surface layer containing fine particles is formed on at least one side of a film made of a styrene polymer having a syndiotactic structure, and the surface layer has a three-dimensional surface roughness SRa. And the number of protrusions per unit area on the center plane of roughness PCC value satisfy the relationship of 15000 × SRa + 500 ≤PCC ≤15000 × SRa + 3500, and the air bleeding speed is 900 seconds or less. The present invention provides a syndiotactic polystyrene-based laminated film having excellent transparency, excellent handling property regardless of film thickness, and good running property and abrasion resistance.

The polystyrene-based polymer having stereoregular syndiotactic structure used in the present invention has a tacticity in which the side chain phenyl group or substituted phenyl group is quantified by a nuclear magnetic resonance method, which is a diad (constituent unit). 85% or more for 2) 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 (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-vinylbenzylpropylether), poly (alkylsilylstyrene) such as poly (p-trimethylsilylstyrene), Examples include poly (vinylbenzyldimethoxyphosphide) and the like.

In the present invention, polystyrene is particularly preferable among the polystyrene polymers. Also,
The polystyrene 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 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-based polymer used in the present invention has a weight average molecular weight of 10,000 or more, more preferably 50,000 or more. If the weight average molecular weight is less than 10,000, it is not possible to obtain a 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 occurs due to an increase in stretching tension, which is not preferable.

Further, the syndiotactic polystyrene 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, as well as transverse / longitudinal stretching.
A stretching method such as a longitudinal stretching method, a longitudinal / transverse / longitudinal stretching method, or a longitudinal / longitudinal / transverse stretching method can be adopted, and the stretching method is selected according to various characteristics such as required strength and dimensional stability. Further, heat setting treatment, vertical relaxation treatment, lateral relaxation treatment, etc. can be performed.

The syndiotactic 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 syndiotactic polystyrene polymer. If it exceeds 10% by weight, breakage easily occurs during stretching, resulting in poor production stability, which is not preferable.

The three-dimensional surface roughness SRa, the number of protrusions PCC on the center plane of the roughness, and the air bleeding speed are
It is adjusted by the film forming conditions of the film and the fine particles added to the surface layer. It is preferable that no fine particles are added to the syndiotactic polystyrene-based polymer layer or the amount is smaller than the amount of fine particles added to the surface layer. The type and amount of fine particles added to the surface layer are three-dimensional surface roughness SR.
a, the number of protrusions PCC on the center surface of the roughness, and the air bleeding speed are not particularly limited as long as they fall within a predetermined range, and for example, silica, titanium dioxide, talc, kaolinite, zeolite, etc. Examples include addition of metal oxides, salts of metals such as calcium carbonate, calcium phosphate and barium sulfate, particles of an organic polymer such as silicone resin and crosslinked polystyrene, and the like. Any of these fine particles may be used alone, or two or more thereof may be used in combination, but the average particle size of the fine particles used is 0.5 μm or more and 2.0 μm or less, and the average particle size is 0.5 μm or more. Is 0.5
It is particularly preferable to mix and add those having a particle size of not more than μm.
Further, the degree of variation in particle diameter (ratio between standard deviation and average particle diameter) is preferably 25% or less. The addition amount is preferably 0.005% by weight or more and 2.0% by weight or less, particularly preferably 0.005% by weight, based on 100% by weight of the syndiotactic polystyrene polymer.
It is preferably from 01% by weight to 1.0% by weight.

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 relationship of 15000 x SRa + 500 ≤ PCC ≤ 15000 x SRa + 3500. When the PCC value and SRa satisfy this relationship, a film having excellent transparency, slipperiness and abrasion resistance can be obtained. On the other hand, when the PCC value is smaller than this range, the running property and the abrasion resistance become poor, which is not preferable. Further, when the PCC value is larger than this range, the transparency is deteriorated, which is not preferable. Also,
SRa is preferably 0.01 μm or more and 0.2 μm or less. If SRa is 0.01 μm or less, running property and abrasion resistance are likely to be poor. If SRa is 0.2 μm or more,
It becomes difficult to obtain a film that simultaneously satisfies both transparency and running property and abrasion resistance.

Furthermore, the syndiotactic polystyrene type biaxially stretched film of the present invention needs to have an air bleeding speed of 900 seconds or less. It is more preferably 700 seconds or less, still more preferably 500 seconds or less. That is, the air release rate is 900
Seconds or less, more preferably 700 seconds or less, further preferably 500
By setting the time to be equal to or less than a second, a syndiotactic polystyrene-based laminated film having good handling characteristics can be obtained regardless of the thickness and strength of the film even during high-speed work. 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. Wrinkles are liable to occur, the winding shape becomes poor, and the film is meandered 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.

The method of forming the surface layer to which the fine particles are added according to the present invention is to apply a resin containing fine particles during or after the formation of a film of a styrene polymer having a syndiotactic structure. Examples thereof include a method and a method of laminating a resin containing fine particles by co-extrusion in a melt extrusion step during film production. It is important that the resin to be laminated has good adhesion with the styrene-based polymer having a syndiotactic structure. When laminating by a co-extrusion method, a thermoplastic resin containing a styrene-based polymer is used. By doing so, particularly good adhesion can be obtained. In the case of coating, acrylic resin, styrene resin, polyester resin, polyurethane resin, polyvinyl resin, polyamide resin, etc. or various modified resins thereof are used alone or in combination as the resin to be used. be able to.

In the case where the film is applied during film formation, it is preferable to apply it before the stretching is completed because the adhesion state becomes better. In this case, since the resin solution to be applied is in a state of being dissolved or dispersed in an aqueous solvent, dissolution or swelling of the film does not occur and the occurrence of breakage of the film during the film forming process is less than that of an organic solvent-based one. preferable. When coating after film formation, surface treatment such as corona treatment can improve the adhesiveness. As a coating method, a roll coating method, a gravure coating method, a roll brushing method, an air knife coating method, a curtain coating method,
The die coating method and the like can be used alone or in combination.

The thickness of the surface layer containing the laminated fine particles is not particularly limited, but in order to keep the transparency in a favorable range, it is 1/2 or less of the total thickness of the film, more preferably 1/3 or less,
More preferably, it is 1/5 or less.

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) 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.
25mm, measuring length 1mm, 2μm 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 at intervals of 2 μm in the width direction of the film, 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 (μm)
I asked.

(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 mm ² .

(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, can a roll with no problems be obtained without causing misalignment of the end of the roll, wrinkles, valves, etc.? 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) Workability of film (sliding property and abrasion resistance) The film is formed into a tape slit into a narrow width, and this is shown in FIG.
Using the measuring device shown in Fig. 2, rub it against a metal guide roll and run it at high speed for a long time.Check the tape tension after rubbing the guide roll and the amount of white powder generated on the surface of the guide roll. As shown below, it was rated and ranked in 5 stages. (A) Slidability 1st class; high tension (very many scratches) 2nd class; slightly high tension (many scratches) 3rd class; medium tension (slightly scratches) 4th class; tension slightly small (almost no scratches) 5th class; Low tension (no scratches) (b) Abrasion resistance 1st class: White powder is generated very much 2nd class: White powder is frequently generated 3rd class: White powder is slightly generated 4th class: White powder is not generated 5 Grade: No white powder

(6) Average particle size Fine particles are observed with a S-510 scanning electron microscope manufactured by Hitachi, Ltd., and photographed ones are magnified and copied, and the outer shape of the fine particles is traced to optionally 200 particles. Particles are 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
(%)

(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.

Examples 1 and 2 (a) Preparation of Polyester Aqueous Solution 5 parts by weight of Bayronal MD16 (manufactured by Toyobo Co., Ltd.) (solid content 25%) and titanium oxide (particle diameter = 0.02 μm, variation = 25%) Of 0.005 parts by weight using a sand mill (zircon beads; particle diameter 1 mm), and further 15 parts by weight of Bayronal MD1200 (manufactured by Toyobo Co., Ltd.) (solid content 25
%) And spherical silica (average particle size = 1.2 μm, variation = 5%) 0.0025 parts by weight (Example 1) or 0.0005 parts by weight (Example 2), spherical silica (average particle size = 0.12 μm, variation) = 5%) and 0.005 parts by weight of isopropyl alcohol and 36 parts by weight of isopropyl alcohol, and further dispersed through a sand mill. Finally, 36 parts by weight of water and 8 parts by weight of benzyl alcohol are added and passed through the sand mill for 1 pass to prepare an aqueous polyester solution. did.

(B) Production of Laminated Film Syndiotactic polystyrene (weight average molecular weight 2500
00) was dried, melted at 315 ° C, extruded from a T-die having a lip gap of 800 µm, adhered to a 40 ° C cooling roll by electrostatic loading and cooled to solidify to obtain a 70 µm amorphous sheet. The amorphous sheet is first preheated to 100 ° C. by a roll and further heated by using four infrared heaters having a surface temperature of 700 ° C., and a film temperature of 139 ° C. is applied in a longitudinal direction of 3.6.
It was stretched twice. The coating solution obtained in (a) above was applied to the uniaxially stretched film by a bar coating method. Then in the tenter,
The film is preheated to 120 ° C and transversely stretched at 120 ° C.
The film was stretched 3.3 times and heat-set at 260 ° C. The obtained laminated film had a total thickness of 6 μm, and the coating film had a thickness of 0.1 μm, and was a uniform coating film. The film properties are shown in the table. When ink was gravure-printed on the coating film of these laminated films, no defect or distortion was observed and good printing was possible. Further, the adhesiveness of the printed portion was evaluated by a tape peeling test (cellophane tape, manufactured by Nichiban Co., Ltd.), and it was found that no peeling was observed and good adhesiveness was exhibited. As a result of evaluating the withstand voltage characteristics of direct current, good results of 480 kV / mm (Example 1) and 485 kV / mm (Example 2) were obtained.

Comparative Example 1 (a) Preparation of Polyester Aqueous Solution 20 parts by weight of Bional MD1200 (manufactured by Toyobo Co., Ltd.) (solid content 25%) and spherical silica (average particle diameter = 1.2 μm)
0.005 parts by weight, isopropyl alcohol 36 parts by weight, water 36 parts by weight, and benzyl alcohol 8 parts by weight, and dispersed using a sand mill to prepare an aqueous polyester solution.

(B) Production of Laminated Film A laminated film was produced in the same manner as in Example 1. The total thickness of the obtained laminated film is 6 μm, and the coating film is 0.1
The coating film had a uniform thickness of μm. The film properties are shown in the table.

Comparative Examples 2 and 3 (a) Preparation of Polyester Aqueous Solution 20 parts by weight (solid content 25%) of Bional MD1200 (manufactured by Toyobo Co., Ltd.) and spherical silica (average particle size = 0.25)
μm, variation = 5%) 0.03 parts by weight (Comparative Example 2) or 0.015 parts by weight (Comparative Example 2), 36 parts by weight of isopropyl alcohol, 36 parts by weight of water, 8 parts by weight of benzyl alcohol were added and a sand mill was added. It was dispersed and used to prepare an aqueous polyester solution.

(B) Production of Laminated Film A laminated film was produced in the same manner as in Example 1. The total thickness of the obtained laminated film is 6 μm, and the coating film is 0.1
The coating film had a uniform thickness of μm. The film properties are shown in the table.

Example 3 Syndiotactic polystyrene (weight average molecular weight 2500
00) 0.5 parts by weight of spherical silica fine particles (average particle size = 1.0 μm, degree of dispersion = 5%) as a protrusion-forming agent per 100 parts by weight.
By weight, spherical silica fine particles (average particle size = 0.12 µm, variation = 5%) were added at 3.0 parts by weight of the polymer chip and the polymer chip to which the protrusion-forming agent was not added at a weight ratio of 1: 9. The mixture (A) and the syndiotactic polystyrene (B) containing no protrusion-forming agent were fed to separate extruders and melted at 310 ° C to produce syndiotactic polystyrene (B) containing no surface-forming agent. The inner layer was laminated in a T-die, extruded from the T-die with a 800 μm lip gap, and adhered to a cooling roll at 40 ° C by an electrostatic loading method to be cooled and solidified to obtain a 70-μm amorphous sheet. Here, the discharge amount of the extruder was controlled so that the total thickness was 70 μm, and the thickness of the syndiotactic polystyrene layer containing the surface forming agent was 0 μm (Comparative Example 3).
It was set to 7 μm (Example 3). The amorphous sheet is first preheated to 100 ° C. by a roll, further heated by using four infrared heaters with a surface temperature of 700 ° C., stretched at a film temperature of 138 ° C. by a factor of 3.6 in the machine direction, and then the film is stretched with a tenter. Preheat to 120 ° C and stretch in the transverse direction at a temperature of 12
The film was stretched 3.3 times at 0 ° C and heat set at 260 ° C. The thickness of the obtained film was 6 μm. The film properties are shown in the table. As a result of evaluating the DC withstand voltage characteristic of this film, a good result of 470 kV / mm was obtained.

Comparative Example 4 Syndiotactic polystyrene (weight average molecular weight 2500
00) 0.5 parts by weight of spherical silica fine particles (average particle size = 1.0 μm, degree of dispersion = 5%) as a protrusion-forming agent per 100 parts by weight.
By weight, spherical silica fine particles (average particle size = 0.12 µm, variation = 5%) were added at 3.0 parts by weight of the polymer chip and the polymer chip to which the protrusion-forming agent was not added at a weight ratio of 1: 9. The mixture is fed to an extruder, melted at 310 ° C, extruded from a T-die with a lip gap of 800 μm, adhered to a 40 ° C cooling roll by an electrostatic loading method, cooled and solidified to form a 70 μm amorphous sheet. Obtained. The amorphous sheet is first preheated to 100 ° C with a roll and the surface temperature is
It is further heated by using four 700 ° C infrared heaters and stretched by a factor of 3.6 in the machine direction at a film temperature of 138 ° C. Then, the film is preheated to 120 ° C by a tenter and stretched in the transverse direction by a factor of 3.3 at a temperature of 120 ° C. It was stretched and heat set at 260 ° C. The thickness of the obtained film was 6 μm. The film properties are shown in the table. When ink was gravure-printed on this film, voids were observed and good printing could not be performed. In addition, as a result of evaluating the adhesiveness of the printed portion by a tape peeling test (cellophane tape, manufactured by Nichiban Co., Ltd.), peeling was observed,
The adhesion was found to be poor. Furthermore, as a result of evaluating the DC withstand voltage characteristic, it was 330 kV / mm, and the DC withstand voltage characteristic was poor. From the table, the films obtained in Examples 1 to 3 are excellent in handleability, slipperiness and abrasion resistance, and also 85% in terms of light transmittance.
The above transparency was excellent.

[0032]

EFFECTS OF THE INVENTION As described above, the present invention provides a syndiotactic polystyrene-based laminated film having excellent transparency, excellent handling properties regardless of the film thickness, and excellent sliding property and abrasion resistance. Done, and thus
The industrial value of the present invention is great.

[0033]

[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; platform 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 also had a problem.

Claims (1)

[Claims] 1. A surface layer containing fine particles is formed on at least one surface of a film made of a styrene-based polymer having a syndiotactic structure, and the three-dimensional surface roughness SRa of the surface layer and the unit of the roughness on the central surface are formed. Number of protrusions per area
A polystyrene-based laminated film having a PCC value of 15000 x SRa + 500 ≤ PCC ≤ 15000 x SRa + 3500 and an air bleeding speed of 900 seconds or less.