JPS595101B2 - Easy-slip film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a biaxially oriented poly p-phenylene sulfide film whose surface roughness is within a certain range and whose coefficient of friction is reduced.

Conventionally, polyethylene terephthalate film, polypropylene film, polyimide film, etc. have been widely used as industrial film materials, but high-quality films that can be melt-formed and are well-balanced in terms of heat resistance, various properties, cost, etc. are still the definitive film. There is no such thing, and consideration is being made in various places. We selected poly p-phenylene sulfide as the material and were considering using this polymer to create a high-grade film, but in order to make it a practical film, we needed to adjust the surface roughness and reduce the friction of the film. We have discovered that if the coefficient is kept below a certain level, we can obtain films and ropes that are excellent in handling and as materials for various types of equipment, and have thus arrived at the present invention. That is, the present invention provides a film in which the coefficient of dynamic friction between films is 0.75 or less at 20°C and 70% relative humidity, and the surface roughness of the film is 0.90μ/5nml.
The present invention relates to a film consisting essentially of biaxially oriented poly-10p-phenylene sulfide, characterized in that: More than 90% mole of the poly p-phenylene sulfide of the present invention is a structural unit of red.

5-)- is preferably a polymer consisting of
If it is less than 90 mol%, crystallinity decreases and biaxial stretching crystallization becomes difficult, making it difficult to obtain satisfactory heat resistance, mechanical properties, etc.

It should be noted that the polymer may contain other copolymerized units as long as they account for less than 10 mol % of the constituent units of the polymer. Such copolymerized units include, for example, trifunctional units (e.g.
-), ether unit (example: 00 s -), sulfon unit (example: 0502 ÷ s -), meta-bonding unit (example 5-
), etc.

It is also possible to cause slight crosslinking by heating the polymerized polymer. Although there are various methods for synthesizing poly p-phenylene sulfide composed of such structural units, a method of reacting p-dihalobenzene with an alkali sulfide or an alkaline earth metal sulfide 35 in a polar organic solvent is suitable, and the polymerization conditions are as follows: A temperature of 200 to 3500C is applied, and the pressure within the polymerization system and the polymerization time are appropriately determined depending on the type of catalyst used and the desired degree of polymerization.

On the other hand, the film forming method is essentially a melt film forming method, and biaxial stretching and heat setting should be performed.

That is, this is a method in which a nearly amorphous film is biaxially stretched and then heat treated for crystallization. To obtain an amorphous film, a polymer is shaped into a film using a press, an extruder, etc., and then rapidly cooled using air, water, a roll, etc. so that crystallization does not progress too much.

The density of an amorphous film is 1.3309/Cc or less, but the density of a film heat-treated after stretching is usually increased to 1.350 or more. As for the stretching method, it is convenient to use a roll or tenter method at a temperature of 80 to 100°C near the glass transition temperature of the polymer, but it is usually possible to obtain an area stretching ratio of 3 times or more, more preferably 7 times or more. This is preferable in terms of the physical properties of the film. The film thus biaxially stretched is heated at 150 to 2800 C to increase the crystallinity.
Preferably, it is heated under tension at a temperature in the range of 250 to 280°C for a sufficient period of time, usually for 1 to 120 seconds. Adjustment of surface roughness, which is a feature of the present invention, can be carried out during the polymerization process, the film forming process, or both.

It is convenient to add inert inorganic particles to the polymer during or after polymerization, or to leave a certain amount of the insoluble salt used for polymerization, but the particles to be added are, for example, average particles. Fine powders of silica, alumina, carbon, glass, calcium carbonate, calcium phosphate, etc. having a diameter of 20 μm or less, or mixtures thereof can be used. Methods that can be used during the film forming process or post-process include use of a roughening roll, stretching after oxidizing the surface, and blasting with a solid material.

When used for various base surface smoothing applications, it is possible to make one side of the base smooth and the other side have large irregularities, and these adjustments can be made within the scope of the present invention by multilayer extrusion,
This can be achieved by processing only one side.

Furthermore, even if both surfaces are smooth with an average diameter of 0.01 μ/50 m, it is possible to adjust the surface friction coefficient by coating. The surface characteristics of the film are characterized by the coefficient of friction and the degree of minute irregularities, and it is preferable from various points of view that both of them be smaller. For example, average 0.90μ/5
Dm (average unevenness of the film surface over a scanning length of 5 m is 0.9
Although the coefficient of friction can be reduced by creating large irregularities exceeding 0μ (meaning 0μ), it is not possible to obtain a good coefficient of friction when the film is used for applications such as graphics or recording and playback. Furthermore, a smooth material with a diameter of less than 0.001 μ/5 m tends to have a large coefficient of friction and is not only difficult to handle but also difficult to actually manufacture. Furthermore, if the friction coefficient exceeds 0.75 in terms of dynamic friction coefficient between the films, it is not preferable because the film may wrinkle or crease during winding. The excellent surface properties of the present invention can be maintained by combining the essential self-lubricating property of the poly-p-phenylene sulfide biaxially stretched film and the provision of minute irregularities on the surface. The film of the present invention provides a very useful base film for precision fields such as photographic film bases, magnetic recording bases, capacitor bases, general electric insulation bases, flexible printed circuit boards, and the like.

Although it is convenient to measure the unevenness of the film surface using a stylus-type surface roughness meter or microscopic measurement using reflection interference or differential interference, it is particularly preferable to measure using a stylus-type surface roughness meter. .

Furthermore, the coefficient of friction can be easily measured by fixing a film to a mirror surface such as metal, bringing the film surfaces into close contact with each other, and moving one side at a constant speed under a constant load.

Further, the film of the present invention may contain a mixture of weathering agents, colorants, antioxidants, etc., metal oxides, and other polymers to the extent that the surface characteristics of the present invention are not impaired.

The present invention will be explained below with reference to Examples.

In the examples, the surface roughness was measured using a universal surface profile measuring instrument SE-3E manufactured by Kosaka Laboratory using a needle with a diameter of 4μ.
It was scanned under a load of 0.079 and the roughness was observed at a magnification of 100,000 times.

The coefficient of friction was determined by measuring the coefficient of dynamic friction between films according to the ASTM D-1894B method at an ambient temperature of 20° C. and a relative humidity of 70%.

Examples 1 Comparative Examples 1 Sodium sulfide (nase hydrate) 1
mole, sodium hydroxide 0.15 mole, lithium acetate 0
．． 501 in the ratio of 8 mol and 4 mol of N-methylpyrrolidone.
The mixture was placed in an autoclave and the temperature was gradually raised to 200 mC to distill off water and a portion of N-methylpyrrolidone.

After adding 1.02 moles of p-dichlorobenzene to this system, the system was pressurized to 4 kg with dry nitrogen and polymerization was carried out at 280 DEG C. for 8 hours with stirring. After washing the contents three times with hot water, three times with acetone, two times with hot water, and once with acetone, the granular polymer was dried at 100° C. for 24 hours. Separately, 12 pieces of calcium carbonate with an average particle size of about 40μ was milled in a ball mill.
The mixture was ground for 0 hours to obtain a fine powder with an average particle size of about 2 μm.

Calcium carbonate before and after pulverization was added in an amount of 0.5% to the previously prepared polymer in a pen shell type mixer, and then molded into cuts (300 to 32'C) using an extruder and then chipped. Next, these polymers were cast onto a water-cooled casting drum to obtain an unstretched film of 350μ, which was then stretched 3.5 times in the machine direction at 9'C with rolls, and further stretched in the transverse direction with a tenter-type stretching machine. (After stretching 3.5 times, heat setting was carried out at about 2700C for 30 seconds under constant length with an electric heater to obtain a 20μ film.

The results shown in Table 1 were obtained by examining what difference would occur when the two types of films thus obtained were made into magnetic tape.
The magnetic tape was manufactured as follows.

◎Composition of magnetic paint γ-Fe2O3 powder 32 parts Carbon black 2.7 parts Vinyrite (
U. C. C. VAGH 4.5 parts S-line (Gutudoritsu) 57025.0 parts Methyl ethyl ketone
22 parts methyl isobutyl ketone
12.7 parts This magnetic paint was coated to a thickness of 5 μm, and after drying, measurements considered to be related to the surface were performed using a helical scan video tape recorder (NV3O2O, manufactured by Matsushita Electric).

As mentioned above, it has been found that the film of the present invention exhibits excellent surface properties even in the precision field.

Example 2 Comparative Example 2 This example relates to a film with an extremely smooth surface.

A polymer synthesized and washed in the same manner as in Example 1 was further added with 1 part of lithium acetate, 2 parts of polymer, and 1 part of N-methylpyrrolidone.
5 parts were mixed and heated in an autoclave at 270° C. for 3 hours with stirring, and then washed with water and acetone in the same manner.

After the dried polymer was formed into a chip, it was biaxially stretched and heat-set in the same manner as in Example 1 to obtain a film of 20 to 25 μm. The surface center line average roughness of this film is 0.00
Although the film was smooth with a value of 5μ/51n01, the coefficient of dynamic friction between the films was 0.69, and no difficulties such as impossibility of winding occurred. On the other hand, polyethylene terephthalate films with similar surface roughness had a coefficient of friction of 1.0 or more and were extremely difficult to handle.

Claims (1)

[Claims] 1. Coefficient of dynamic friction between films is 20℃, relative humidity is 70
A biaxially oriented film consisting essentially of poly-p-phenylene sulfide, characterized in that the film surface roughness is less than or equal to 0.75% and has an average film surface roughness of less than or equal to 0.90μ/5mm.