DE3829399A1 - Magnetic recording medium - Google Patents

Abstract

The invention relates to a magnetic recording medium comprising a nonmagnetic support (carrier, base), a magnetisable layer and a base coat between the two, which is characterised in that the base coat contains the following constituents: (A) one or more resins selected from groups consisting of polyester resins containing hydroxyl groups and polyurethane resins containing hydroxyl groups, (B) a polyisocyanate compound, (C) one or more compounds selected from groups consisting of organometallic compounds and tertiary amine compounds, and (D) a carbon black having a mean diameter of individual particles of less than 50 mu m and an oil absorption of less than 100 g of DBP/100 g, and in that the (A) : (D) ratio is between 30 : 70 and 70 : 30 (weight ratio) and in that the content of (B), based on (A), is from 15 to 50 % by weight and the content of (C), based on (A) is from 0.5 to 5 % by weight.

Description

The invention relates to a magnetic Recording medium, in particular a magnetic Recording medium of the order type, consisting from a non-magnetic carrier, a magnetizable layer and one in between arranged primer.

In recent years, magnetic Recording media to increased recording density more and more claimed and for this purpose one examines the improvement of the magnetizable layer, such as fine pulverization magnetic material, increasing the filling and thinning the magnetizable layer. However, the improvement in terms of made magnetizable layer, then comes a tendency to the appearance that the adhesion the magnetizable layer on the carrier and the Strength of the coating decrease and that with it their durability becomes lower. To this, too improve, are already applied to procedures  those on the carrier a primer is applied from an organic Solvent dissolved polyester or polyurethane resin consists.

The primers used so far However, have disadvantages that when you order the magnetizable paint on a primer coat, which is formed after application and drying, the primer by a magnetizable Paint containing, organic solvent swells or is dissolved and that thereby the Interface between the magnetizable layer and the base coat loses smoothness, and therefore that the magnetizable layer on its surface loses its smoothness. As a result, problems such as performance decrease arise and increased power fluctuation. One has therefore introduced a procedure in which the swelling and the solution because of the solvent on a Minimum should be kept by the Primer liquid is a polyisocyanate compound is added to that in the primer liquid crosslinked resin. The attempt has but so far no satisfactory result guided.  

Means of solving the problems

In this situation, the inventors have Many investigations have been carried out and found out that the swelling and the solution because of the solvent in magnetizable Paint can be largely suppressed and that thus a magnetic recording medium with good surface texture and high Durability is achieved by using as ingredients, that make up the primer, a particular resin with Hydroxyl groups, polyisocyanate compounds, one or several connections made up of groups organic metal compounds and tertiary Amine compounds are selected, as well as a certain soot can be used. So that was the Invention completed.

Namely, the invention consists of a magnetic recording medium consisting of a non-magnetic carrier, a magnetizable Layer and arranged in between Primer, which is characterized that the base coat has the following ingredients includes:

• (A) one or more resins by groups from polyester resins with hydroxyl groups and  Polyurethane resins with hydroxyl groups to be selected,
• (B) a polyisocyanate compound,
• (C) one or more compounds, that of groups of organic metal compounds and tertiary amine compounds are selected, and
• (D) a carbon black having a mean diameter individual particles below 50 microns and a Oil intake lower than 100 g DBP / 100 g having,

and that a content ratio of (A) to (D) between 30: 70 and 70: 30 (weight ratio) and that a content of (B), based on (A), 15 to 50 wt .-% is and a content to (C), based on (A), 0.5 to 5 wt .-%.

According to the invention, all polyester and polyurethane resins without particular limitation used as far as they are at their ends of the molecule or in branched chain hydroxyl groups respectively. So are among those on the market come polyester resins z. Vilon 103, Vilon 200, Vilon 280, Vilon 290, Vilon 300 and Vilon 500 (manufactured by TOYOBO CO., LTD.), Unitika-Ellitel UE-3200, Unitika-Ellitel UE-3201,  Unitika-Ellitel UE-3300 and Unitika-Ellitel UE-3400 (Made by UNITIKA LTD.).

Among the marketed Polyurethane resins are also Nippolan 5032, Nippolan 5033 and Nippolan 2301 (made by NIPPON POLYURETHANE KOGYO K.K.).

These are the inventions used polyisocyanate compounds (B) here um Compounds that are in a molecule at least have two isocyanate groups, wherein they be aromatic, aliphatic or cycloaliphatic can. These are, for example, the following Market goods called: Coronate L, Coronate HL and Coronate EH (made by NIPPON POLYURETHANE KOGYO K.K.), Sumidur L, Sumidur IL, Desmodur HL, Sumidur N, Sumidur HT and Sumidur W (manufactured by SUMITOMO BAYER URETHANE K.K.).

According to the invention, based on 100 parts by weight Polyester resins with hydroxyl groups, polyurethane resins with hydroxyl groups or their mixture, 15 to 50 parts by weight of polyisocyanate used. If the polyisocyanate compound is less than 15 Parts by weight, so is the crosslinking reaction insufficient. Is the polyisocyanate compound more than 50 parts by weight, then it adversely affects  take a long time to complete the reaction of her Isocyanate groups is completed. Not reacted remained polyisocyanate compound brings the enhanced blocking feature of the Primer, so that they u. a. the disturbing Adhering to the roller during the order of magnetizable paint has the consequence.

As the organic used in the invention Metal compounds may be mentioned: z. Eg iron (III) - trisazetylazetonate [Fe (C₅H₇O₂) ₃], Manganese (III) trisazetylazetonate [Mn (C₅H₇O₂) ₃], Dibutyltin dioctoate, dibutyltin diacetate, Dibutyltin dilaurate, dioctyltin dilaurate, Tin octenoate, tin oleate, lead naphthenate, lead oleate, Tetraisopropyl titanate and tetra-n-butyl titanate.

As the tertiary used in the invention Amine compounds may be mentioned: z. B. triethylenediamine, triethylamine

The components (C) are preferably organic metal compounds, in particular Iron (III) -trisazetylazetonat.

The amount of use of ingredients (C) is 0.5 to 5 wt .-%, based on ingredients (A). If it is less than 0.5% w / w, so requires the primer for the conclusion their hardening reaction takes a lot of time while themselves Defects, such as blooming of the surface of the primer, when exceeding 5 wt .-% result.

The component (D) used in the invention is a certain soot, which has a mean diameter of individual Particles below 50 microns and an oil intake lower than 100 DBP / 100g. Only with a soot, the fulfilling these conditions is the excellent effect to achieve the invention.

The component (D) is in such a Amount uses a content ratio of (A) to (D) between 30:70 and 70:30 (weight ratio) lies.

In the invention it is very much on the Amount ratio of (A), (B), (C) and (D) with each other. It is necessary that As already mentioned above, a salary ratio from (A) to (D) between 30: 70 and 70: 30  (Weight ratio) is and that a salary to (B), based on (A), 15 to 50% by weight and a content of (C), based on (A), 0.5 to 5 wt .-%. It is only then possible to the good primer according to the invention obtained when these conditions satisfied have been.

The primer is formed by that each of the above components (A) to (D) in an organic solvent, such as acetone, Methyl ethyl ketone, cyclohexanone and ethyl acetate, dissolved to form a primer liquid After the engraving process, the Reverse roll coating or other method applied to a nonmagnetic support and then dried. The primer liquid may be to the antistatic or light-shielding To improve properties, an inorganic Pigment, like another soot and titanium oxide, be added.

The magnetizable paint constituting the magnetizable layer of the magnetic recording medium of the present invention is not particularly limited in its components. The common materials may be used as they are. For example, it is possible to use ferromagnetic powder as the magnetizable powder, such as γ- iron oxide, Co-containing γ- iron oxide, reduced iron powder, and alloy powder such as iron-cobalt-nickel. Synthetic or semi-synthetic polymer compounds such as polyvinyl chloride, vinyl chloride-vinyl acetate copolymer and its partially saponified derivatives, polyvinyl butyral, phenoxy resin, epoxy resin, polyester resin, polyacrylonitrile, polyurethane, polyacrylic acid ester, polymethacrylic acid ester, polyvinylidene chloride, cellulose acetate butyrate, nitrocellulose in single or mixed form may also be used as binders same are used. It is also desirable to add plasticizers such as dibutyl phthalate and dioctyl phthalate, curing agents such as polyisocyanate compound, abrasives such as α- iron oxide, alumina and chromium oxide, lubricants such as fatty acid esters and fatty acids, antistatic agents such as carbon black and quaternary ammonium salt, and dispersants such as lecithin and alkylphosphoric acid esters.

As a non-magnetic carrier is used according to the invention preferably a polyethylene terephthalate Movie.  

embodiment

The invention is based on the embodiments explained in more detail to which they, however is not limited.

example 1

There were

Vilon 200 68.3 parts by weight, (Polyester resin of TOYOBO CO., LTD.) @ Sumidur N-3200 16.4 parts by weight, (Polyisocyanate compound from SUMITOMO BAYER) @ Iron (III) -trisazetylazetonat 2.1 parts by weight, soot 68.3 parts by weight, (average particle size 23 mμ and oil absorption 56 g DBP / 100 g) @ methyl ethyl ketone 241.4 parts by weight, toluene 241.4 parts by weight and cyclohexanone 361.2 parts by weight

mixed in a sand mill, and the mixture became on a 75 mμ polyethylene terephthalate Film applied so that a dry film thickness of 0.5 μm. After drying forms a primer.

Then you have under approximately constant Print a certain area of the base coat with a cotton swab continuously rubbed, the  sufficiently soaked with a methyl ethyl ketone has been, and even after 20 times of friction no triggering of the primer in Methyl ethyl ketone was detected.

Example 2

A mixture of

Nippolan 2301 68.3 parts by weight, (Polyurethane resin from NIPPON POLYURETHANE KOGYO) @ Sumidur N-3200 16.4 parts by weight, (Polyisocyanate compound from SUMITOMO BAYER) @ Iron (III) -trisazetylacetonat 2.1 parts by weight, soot 68.3 parts by weight, (average particle size 23 mμ and oil absorption 56 g DBP / 100 g) @ methyl ethyl ketone 241.4 parts by weight, toluene 241.4 parts by weight and cyclohexanone 361.2 parts by weight

was in the same manner as in Example 1 treated to form a primer. The Tripping test of the primer was subsequently in the same manner as in Example 1 carried out. Even after 20 times rubbing has no base coat in methyl ethyl ketone triggered.

Example 3

A mixture of

Ellitel 35 parts by weight, (Polyester resin from UNITIKA LTD.) @ Nippolan 2301 35 parts by weight, Coronate L. 20 parts by weight, (Polyisocyanate compound of NIPPON POLYURETHANE KOGYO) @ Iron (III) -trisazetylazetonat 2.5 parts by weight, soot 57 parts by weight, (average particle size 31 mμ and oil absorption 70 g DBP / 100 g) @ methyl ethyl ketone 240 parts by weight, toluene 240 parts by weight and cyclohexanone 365 parts by weight

was in the same manner as in Example 1 treated to form a primer. The Tripping test of the primer was subsequently in the same manner as in Example 1. Even after 20maligen friction has no Primer applied.

Comparative Example 1

In place of carbon black in Example 1 was a Another soot that uses an average grain size of 24 μm and an oil absorption of 170 g DBP / 100 g having. This became a primer in the same  Manner as in Example 1 formed. The same Testing as in Example 1 has triggered the Primer painted at 10 times rubbing.

Comparative Example 2

It has the same manner as in Example 1 worked with difference that contrary to Example 1 110 parts of Vilon and 25 parts of carbon black were used. At 9 times rubbing has the primer is triggered.

Comparative Example 3

It has the same manner as in Example 1 worked with difference that contrary to Example 1 31 parts of Vilon and 91 parts of carbon black zum Use came. At 7 times friction has the primer is triggered.

Claims (2)

Magnetic recording medium consisting of a nonmagnetic support, a magnetizable layer and a primer coat disposed therebetween, characterized in that the basecoat contains the following components:

• (A) one or more resins selected from groups of polyester resins having hydroxyl groups and polyurethane resins having hydroxyl groups,
• (B) a polyisocyanate compound,
• (C) one or more compounds selected from groups of organic metal compounds and tertiary amine compounds, and
• (D) a carbon black having a mean diameter of individual particles below 50 mμ and an oil absorption lower than 100 g DBP / 100 g,

and that a content ratio of (A) to (D) between 30: 70 and 70: 30 (weight ratio) and that a content of (B), based on (A), 15 to 50 wt .-% and a content of (C), based on (A), 0.5 to 5 wt .-%.