JPS60151824A - Magnetic recording tape - Google Patents

Abstract

PURPOSE:To form the titled magnetic recording tape which is capable of traveling stably, without any variations of the output and dropouts, and having a high S/N ratio by incorporating a perfluoroalkyl compd. into the film of a backcoat layer. CONSTITUTION:The film of a backcoat layer is basically constituted of a binder resin, inorganic or organic fine powder, and a perfluoroalkyl compd. The perfluoroalkyl compd. has extremely low surface tension, enhances the wettability of a substrative base film and the backcoat layer, and improves the adhesiveness. A compd. contg. a fluoroalkyl group having 3-15C in the molecule is used as the perfluoroalkyl compd. The film of the backcoat layer consists of a mixed system obtained by mixing 100pts.wt. binder resin and 20-250pts.wt. fine powder. And 1-10pts.wt. perfluoroalkyl compd. is added to 100pts.wt. binder resin. In this case, 2-5pts.wt. perfluoroalkyl compd. is preferably added.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording tape used in audio equipment, video equipment, computers, and the like.

The structure of the conventional example and the opening of the leopard! .

As video tape recorders and other devices become smaller and lighter and their densities become higher, magnetic recording tapes used for them are being made with magnetic materials to achieve high output and high S/N ratio in the high frequency range. It has become necessary to have an extremely smooth surface finish on the layer.

However, if the surface is finished smooth, the slipperiness deteriorates, resulting in a fatal flaw in the running performance of the tape.

In other words, tape squeal occurs during running, and irregular winding occurs during winding and rewinding. If such a tape is used, the output will fluctuate due to tension fluctuations. It also causes deformation and loss of the tape, causing dropouts.

As a method to solve these drawbacks, a method has been implemented in which a slippery film made of inorganic powder and a binder resin is formed as a back coat layer on the opposite surface to the magnetic recording surface.

However, conventional back coat layers do not have perfect adhesion to the base surface, and repeated running causes powder to fall off or peel off from the base surface, causing dropouts.

OBJECTS OF THE INVENTION The object of the present invention is to provide a magnetic recording medium that has a backcoat layer that has a friction coefficient of 3 B and a small increase in the coefficient of friction, has good adhesion to the base surface, and has excellent running durability without powder falling off. The purpose is to provide tapes.

Structure of the Invention The magnetic recording tape of the present invention has a magnetic layer formed on one main surface of a non-magnetic base film, and a back coat layer formed by dispersing fine powder in an organic resin on the other main surface. The back coat layer film contains a perfluoroalkyl compound.

The magnetic recording tape of the present invention will be explained in more detail below.

The back coat layer film, which is a feature of the present invention, is basically composed of a binder resin, an inorganic or organic fine powder, and a par-70 alkyl compound.

As the binder resin used in the present invention, many thermoplastic and thermosetting resins conventionally known as binders for magnetic paints or binders for back coat layers can be used. Typical examples of these include thermoplastic and thermosetting urethane resins, cellulose resins such as nitrocellulose, polyester resins, vinyl chloride resins such as vinyl chloride-vinyl acetate-vinyl alcohol copolymer resins, etc. These resins include resins and epoxy resins, and these resins can be used alone or as a mixture of each.

Preferred requirements for these binder resins for the back coat layer include good affinity with the fine powder dispersed in the resin;
The resin must have excellent dispersibility, the glass transition temperature of the resin, which is related to the strength of the film, must be approximately C or higher, and the resin itself must have a low coefficient of friction.

Next, as the fine powder used in the present invention, many fine powders conventionally used for back coat layer films can be used. Typical examples of these are carbon powder, calcium carbonate powder, and titanium dioxide powder.

Zinc oxide powder, etc., and these can be used alone or as a mixture of each.

Next, the perfluoroalkyl compound contained in the backcoat layer film of the present invention has an extremely low surface tension, which improves the wettability between the support base film and the backcoat layer 5 vane, and improves the adhesion. be.

These barfluoroalkyl/14yl compounds consist of compounds having a fluoroalkyl group having about 3 to 15 carbon atoms in the molecule, and typical examples include perfluoroalkyl carboxylic acids, barfluoroalkyl carboxylates,
These include perfluoroalkyl phosphate esters, per70-roalkylammonium salts, perfluoroalkyl betaines, per70-roalkylamine oxides, perfluoroalkylethylene oxide adducts, and the like. Among these compounds, perfluoroalkylamine oxide provides particularly favorable effects.

The back coat layer film consists of a mixed system in which the fine powder is in the range of 20 to 250 parts by weight per 100 parts by weight of the binder resin, and the Par 70 alkyl compound is in the range of 1 to 10 parts by weight per 100 parts by weight of these mixed systems. It is added within the range of 100%. The preferred perfluoroalkyl compound content is 2 to 5 parts by weight.

If necessary, other fatty acids, fatty acid esters, etc. can be added to the back coat layer film of the present invention as long as the effects of the perfluoroalkyl compound are not hindered.

Each component constituting the back coat layer is made into a paint using a conventionally known method such as a ball mill or a sand mill, and the coating is applied to the base film in the form of a film and dried and hardened to form the back coat layer. do.

The thickness of the back coat layer is preferably 0.3 μm to 1.0 μm.

Description of examples The present invention will be specifically explained below using actual cases.

Thickness 11. A magnetic layer made of iron powder was provided on the surface of the ollm PET base film, and a back coat layer was provided on the opposite surface. The thickness of the magnetic layer was 3.6 μm. The back coat layer was made into a paint with the composition of the actual case and comparative example shown below.
A film with a thickness of 0.6 μm was formed. Note that each film was cured by heating at 60C for 15 hours. After forming the back coat layer, it was cut into a tape by cutting into 'h inch pieces.

Example 1 7 H) Nitrocellulose 40 parts (R8:112) Coronate L 10 parts or more was the basic composition, and to this were added 2 parts each of the par 70 alkyl compounds shown in Table 1 to form a back coat paint. did. Note that a comparative example was one in which no perfluoroalkyl compound was added.

Example 2 Urethane resin 20 parts (5IT310) Polyester resin 10 parts (Toyobo: RV-530) Nitrocellulose 30 parts (R8: μ) Calcium carbonate powder 60 parts (Shiraishi Kogyo: Homocal D) Coronate L 12 parts or more The composition was used as a back coat paint. Comparative Example 2 was prepared by removing only the par-70 loalkylamine oxide from this composition and using it as a back coat paint.

The prototype tape was evaluated by the following tests.

1 Measurement of the coefficient of dynamic friction of virgin tape 2 The tape is
Measurement of the coefficient of dynamic friction and observation of running scratches on the back coat layer surface after 200 passes of repeated running on an H8 video deck.

3 Peeling test of back coat layer The coefficient of dynamic friction of the tape was measured by bringing the back coat side of the tape into contact with a stainless steel rod of 4.0 mm diameter, winding it to 18 oO, and sliding the tape at scH/sec. The loads on the entry and exit sides were considered. The load on the entry side is 20.05
'.

In the peel test, the tape was pasted on a glass plate with a smooth surface with the back coat layer on the surface, fixed so that the back coat surface was horizontal, and a 4φ steel ball was brought into contact with the surface. Add a load of 409 to the line and move 10cm/SE
It is expressed as the number of times it takes for the back coat layer to peel off after repeated sliding at a speed of 9 b.

The surface roughness of the back coat layer was measured using a stylus type surface roughness meter and expressed as a peak value (Rmax).

The results of each measurement are shown in the table below.

Below Margin 1 o Base 11 Vane JP-A-151824 (4) Table 2 As is clear from the Examples and Comparative Examples in the above table, the back coat layer according to the present invention consists of binder resin, fine powder, and par 70. Since it is composed of a dispersed film of an alkyl compound, the friction coefficient is small, and the friction coefficient does not increase much even during repeated running, and it also has excellent adhesion to the base film, preventing scraping and powder falling. It has extremely high durability.

Effects of the Invention As detailed above, by providing the back coat layer according to the present invention, it is possible to realize a magnetic recording tape that can run stably and has a high S/N ratio without output fluctuations, dropouts, etc. I can do it 13 times.

Claims (2)

[Claims] (1) A magnetic recording tape in which a magnetic layer is formed on one main surface of a non-magnetic base film, and a back coat layer is formed on the other main surface, the back coat layer having a par.
A magnetic recording tape characterized in that it contains a zero-mouth alkyl compound. (2) The magnetic recording tape according to claim 1, wherein the par-70 alkyl compound is a par-70 alkylamine oxide.