DE2610694A1 - MAGNETOGRAM CARRIER - Google Patents

Description

TOB Pilefrtrlk Weife * Wolfen, July 9th 1975

PN 646 Bh

Magnetogram carrier

The invention relates to a magnetogram carrier, consisting of a non-magnetic base on which there is a vinyl polymer-containing binder layer with finely divided magnetic pigments and optionally further additional layers.

Such magnetogram carriers are z. B. in disc, tape and card form are known and are used to store digitally and analogously encoded information.

The binders used are of particular importance for the magnetic and physical-mechanical properties and thus the area of application of such magnetogram carriers. There are known binder components with good properties for magnetogram carrier coatings, which essentially consist of a binder base component of high hardness and a plasticizer component. The basic binder component is usually a vinyl copolymer Pie plasticizer component is advantageously a higher molecular weight product Components that are particularly effective are linear polyurethanes with a higher molecular weight

Such products can be practically free of terminal hydroxyl groups or contain hydroxyl end groups. Polyurethanes free from hydroxyl groups have the disadvantage of limited solubility and compatibility problems with Viaylpolymerisaten · An undesirable one arises The two-phase system and all a sequence of it have with it coated magnetogram carrier an inhomogeneous magnetic layer

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ORIGINAL INSPECTED

By using polyurethane flexibilizers containing hydroxyl groups Although the above disadvantages can be avoided, an increasing hydrophilicity of the entire binder must be achieved ! systems that lead to stickiness under thermal stress and poor mechanical strength of the magnetic layer of the magnetogram carrier, accept

The purpose of the invention is to produce magnetogram carriers with better physical-mechanical properties.

The invention is based on the object of a plasticizer for the vinyl polymers used as binders for magnetogram carriers, this plasticizer being a Is hydroxyl-free polyurethane, but does not have the disadvantages mentioned above *.

According to the invention, the object is achieved in that the Binder 5-95 percent by weight of a linear high molecular weight polyurethane with butanediol (1,3) segments, which is practically free of hydroxyl groups.

The introduction of the butanediol (1,3) segments into the polyurethanes is usually done so that in the production of the used for the production of the polyurethanes Polyols butanediol-1,3 ice alcohol component is used, It can also be done by using conventional polyol components, 1,3-butanediol in the Chain extension phase as a chain extension agent used -by.

Compared to the plasticizers used up to now, there is an improved solubility and a broad long-term tolerance range found with vinyl polymers. In addition, on magnetogram carriers, those with the polyurethane components according to the invention can be produced, a significantly improved abrasion resistance established.

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JM shows that the intrinsically improved effects are not _{bound by what is present in butanediol (1 t} 3) segients, but rather develop clear maxima with a certain content of butanediol (1,3) segments, which depend on the solvents or basic binder components used and must be determined empirically in each case. The maxima of the improvement in solubility are relatively broad, those of the improvement in compatibility with the vinyl polymers are relatively narrow.

The one defined with the term solubility improvement The influence of the soap shaft is clearly shown in the stability The ferromagnetic binder-pigment dispersion used for the coating, while the influence of the compatibility process can only be seen on the finished record after it has been coated, as the magnetic layer is clearly homogeneous when viewed under an electron microscope mmd germs can detect subsequent pore formation and at the same time with this effect it improves the abrasion resistance and the elastic properties can be observed.

The non-magnetic supports can be flexible or rigid Materialion from z. B. acetyl cellulose, polyvinyl chloride, Polypropylene or Polyäthyltnterephthalat as well as from Metal, glass or paper can be used.

All known magnetic pigments for magnetogram carriers such as B. acicular CrO2 or V ^ -Fe ₂ Oo as well as metal powder can be used

The invention is described in more detail below with the aid of examples explained.

300 g acicular gas / - * · ₂ ° 3 ^with an average particle length of 0 _t 4 mi are a coercive force of 290 A. Oa ~ ¹ as well as 12 g of an aoetyle of high conductivity are mixed with one another in aim · ΙΛ # μ * $ ,, the · «* figuring components, umtar Bühram almfatrageat

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90 g eir.ee polyether ester urethane _t cas in the molecule butanediol - (1.3) -><.-: iaente contains, 10 g of a polyvinyl formal which contains viKvΐί · ΐί · oho 1 and vinyl acetate groups, 3.1 g of a phc3i .horh? .ltigen dispersant, 600 ml of tetrahydrofuran, 4CC ml of 1,2-dichloroethane, 300 ml of N. U -dimethylformamide. The mixture is stirred in a ball mill with a grinding pot volume of 1 liter using quartz glass beads with an average diameter of 1.5 µm. ois dispersed for complete homogenization. The dispersion is deaerated, filtered through a textile filter with an average pore size of 3 μm and applied in a known manner to a carrier material made of polyethylene terephthalate, the drying percentage being preceded by alignment of the pigment particles in the longitudinal direction as a result of the action of a magnetic field en aftertreatment of the coated carrier film for the purpose of surface treatment, which consists of a calendering at 100 ⁰ U.

Example 2

The procedure is as in Example 1, but instead of 300 g ^ -FepO-, 400 g ferromic & gne tables ε needle-shaped Chromium dioxide used. The addition of acetylene black is not necessary because of the good conductivity of the chromium dioxide.

Comparative example

M ^a .n verfahrt like "in Seispiel 1. Instead of Polyätheretterurethf-ns a polyetherurethane is used on the basis of '.Tetrahydrofuran and p ^ -Dipbenylmethandiieocyenat.

Compared to the comparative example, the magnetogram carriers according to examples 1 and 2, the following advantages: improved adhesion to the substrate, improved heating behavior and improved service life compared to layer abrasion

In the table below, the results of Examples 1 and 2 and of the comparative example are compared with one another.

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BATH ORIGINAL

Tabel

Example 1 Example 2 Comparative example

Adhesion to the carrier 1 1 4

Obtain lelbungsv 1 2 3

Lifetime versus

Layer abrasion Λ 1 4

1 = very good behavior

2 = good behavior

3 = moderate behavior

4 = insufficient behavior

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Claims (1)

^mm C ·· Pat responded Magnetogram carrier, consisting of a non-magnetic Backing on which there is a vinyl polymer-containing binder layer with finely divided, finely divided magnetic pigments and possibly another additional layer, characterized in that the binder 5 to 95 percent by weight of a linear, high molecular weight Polyurethane with butanediol (1,3) segments, which is practically free of terminal hydroxyl groups. 609852/0610