Abstract: A magnetic recording medium is disclosed, comprising a non-magnetic support having provided thereon at least a lower non-magnetic layer comprising a binder having dispersed therein a non-magnetic powder and an upper magnetic layer comprising a binder having dispersed therein a ferromagnetic powder which has been formed on the lower non-magnetic layer while the lower non-magnetic layer is wet, wherein the upper magnetic layer has a dry thickness of not more than 1.0 .mu.m, the ferromagnetic powder in the upper magnetic layer has an average major axis of not more than 0.3 .mu.m and an average crystallite size of not more than 300 .ANG., the non-magnetic powder in the lower non-magnetic layer contains (i) a non-magnetic metal oxide powder and (ii) carbon black having an average primary particle diameter of less than 20 nm at a weight ratio of from 95/5 to 60/40, and the lower non-magnetic layer contains a polyurethane having at least three hydroxyl groups in the molecule thereof and a polyisocyanate compound.

Abstract: A magnetic recording comprising a non-magnetic support having thereon first and second magnetic layers containing a binder and a ferromagnetic powder. In a first embodiment, the content of the binder in each magnetic layer containing a vinyl chloride resin or a cellulose resin is characterized in relation to the quantity of the ferromagnetic powder contained therein. In a second embodiment, each of the magnetic layers is characterized in terms of a difference in glass transition point of a polyurethane resin contained therein. In a third embodiment, each of the magnetic layers is characterized in terms of thickness and polyisocyanate content, wherein the content of the polyisocyanate in the first magnetic layer is at least one part by weight larger than the amount of the polyisocyanate in the second magnetic layer.

Abstract: A magnetic recording medium comprising a non-magnetic support having at least two magnetic layers formed thereon, the at least two magnetic layers being formed by providing, in sequence, a first magnetic layer containing first ferromagnetic powder and a first binder on a surface of the non-magnetic support and then providing a second magnetic layer containing a second binder and second ferromagnetic powder while the first layer is in a wet state, the first magnetic layer containing the first binder in an amount of 10 to 27 parts by weight based on 100 parts by weight of the first ferromagnetic powder, the second magnetic layer containing the second binder in an amount of 14 to 30 parts by weight based on 100 parts by weight of the second ferromagnetic powder, the amount of the first binder contained in the first magnetic layer being smaller than that of the second binder contained in the second magnetic layer with a difference therebetween being from 0.

Abstract: A magnetic recording medium comprising a non-magnetic support having thereon a plurality of magnetic layers each comprising a ferromagnetic powder dispersed in a binder, wherein the layer located within a thickness of 0.5 .mu.m from an uppermost surface of said plurality of magnetic layers and a layer located within a thickness of 0.5 .mu.m above the adjacent non-magnetic support have a higher packing density of ferromagnetic powder than an interlayer interposed therebetween. In a preferred embodiment, the interlayer consists of two layers and there are provided on the non-magnetic support a 1st magnetic layer, a 2nd magnetic layer, a 3rd magnetic layer and a 4th magnetic layer in this order from the non-magnetic support; the sum of the thickness of said 3rd magnetic layer and said 4th magnetic layer being not more than 3.5 .mu.m.

Abstract: A magnetic recording medium comprising a nonmagnetic support having provided thereon a magnetic layer comprising a ferromagnetic powder dispersed in a binder, wherein said ferromagnetic powder has a specific surface area of 40 m.sup.2 /g or more as measured by the BET method; said magnetic layer further comprises carbon black having an average particle diameter of from about 20 to 120 m.mu.; and said binder comprises the combination of (1) a vinyl chloride resin containing a phosphate ester group represented by ##STR1## wherein M.sub.1 and M.sub.2, which may be the same or different, each represents Na, K, Li, H, N.sym.R.sub.3, or N.sym.HR.sub.2 wherein R represents an alkyl group or a hydrogen atom, and (2) at least one resin other than said vinyl chloride resin containing at least one of --SO.sub.3 M, --OSO.sub.2 M, --COOM, and ##STR2## wherein M, M.sub.1, and M.sub.2, which may be the same or different, each represents Na, K, Li, H, N.sup.4 .sym. R.sub.3, or N.sup..sym. HR.sub.

Abstract: A magnetic recording medium comprising a nonmagnetic support having provided thereon a magnetic layer comprising a ferromagnetic powder dispersed in a binder, wherein said ferromagnetic powder has a specific surface area of 40 m.sup.2 /g or more as measured by the BET method; said magnetic layer further comprises Al.sub.2 O.sub.3 particles having an average particle diameter of from about 0.1 to 0.5 .mu.m; and said binder comprises the combination of (1) a vinyl chloride resin containing a phosphate ester group represented by ##STR1## wherein M.sub.1 and M.sub.2, which may be the same or different, each represents Na, K, Li, H, N.sym.R.sub.3, or N.sym.HR.sub.2 wherein R represents an alkyl group or a hydrogen atom, and (2) at least one resin other than said vinyl chloride resin containing at least one of --SO.sub.3 M, --OSO.sub.2 M, --COOM, and ##STR2## wherein M, M.sub.1, and M.sub.2, which may be the same or different, each represents Na, K, Li, H, N.sym.R.sub.3, or N.sym.HR.sub.

Abstract: A magnetic recording medium having at least two magnetic layers is disclosed, comprising first and second mangetic layers which are successively formed in order on a nonmagnetic support, wherein a coercive force (Hc) of said second magnetic layer is 5.times.10.sup.4 to 1.5.times.10.sup.5 A/m, a ratio (Br/Hc) of a residual magnetic flux density (Br) of said second magnetic layer to the coercive force (Hc) is 2.0.times.10.sup.-6 H/m or more, SFD of said second magnetic layer is 0.6 or less, an average length in the long axis of magnetic particles in said second magnetic layer is 0.25 microns or less, a center line average surface roughness (Ra) of said second magnetic layer is 1/10 or less of the average length in the long axis of the magnetic particles, and a coercive force (Hc') of said first magnetic layer is 2.times.10.sup.4 to 1.times.10.sup.5 A/m.

Abstract: A magnetic recording medium comprising two or more magnetic layers containing ferromagnetic substance dispersed in a binder provided on a non-magnetic substrate is disclosed, which is characterized in that a ferromagnetic substance whose water content is adjusted within the range of from 0.4 to 2.0 wt. % by moisture conditioning is used in the upper layer of the magnetic layers and a ferromagnetic substance having an water content less than by at least 0.1 wt. % than that of the feromagnetic substance used in the upper layer is used in the lower layer of the magnetic layers.

Abstract: A magnetic recording medium which comprises plurality of magnetic layers comprising at least first and second magnetic layers which are successively formed on a surface of a polyethylene terephthalate support, wherein said support contains inert inorganic particles having an average particle size of from 0.5 to 0.7 microns, a standard deviation of 0.1 microns or less and the surface of said support has a center line average roughness (Ra) of 16 nm or less and a density of protrusions (Ds) of 6000/mm.sup.2 or more in the case of protrusions of 0.7 microns of more.

Abstract: A magnetic recording medium comprising a non-magnetic support having provided thereon in this order, a first magnetic layer containing ferromagnetic particles dispersed in a binder and a second magnetic layer containing ferromagnetic particles dispersed in a binder, whereinsaid second magnetic layer contains particles of an abrasive material having a Mohs' hardness of 8 or more in an amount of 1 to 15 wt % based on the weight of the ferromagnetic particles contained in the second magnetic layer,said first magnetic contains particles of an abrasive material having a Mohs' hardness less than 8 in an amount of 5 to 50 wt % based on the weight of the ferromagnetic particles contained in the first magnetic layer, andthe proportion of the abrasive material to the ferromagnetic particles in said first magnetic layer is larger than that in said second magnetic layer.

Abstract: A magnetic recording medium exhibiting good still durability and good running properties is disclosed, which comprises a non-magnetic support having thereon a first magnetic layer and a second magnetic layer in sequence, the first and second magnetic layers containing ferromagnetic powder and a binder, wherein a fatty acid ester (A) having the following structure is contained in the first magnetic layer and a fatty acid ester (B) having the following structure is contained in the second magnetic layer: ##STR1##

Abstract: A method of producing a magnetic recording medium comprises the steps of kneading and dispersing ferromagnetic powder, binder and non-ferromagnetic powder to obtain magnetic coating solutions, and applying a plurality of the magnetic coating solutions on a non-ferromagnetic substrate to form a plurality of magnetic layers on the substrate. In the kneading and dispersing step, a magnetic coating composition containing a ferromagnetic powder and a solvent of 15 to 30 wt % of the ferromagnetic powder is kneaded by a two-shaft continuous kneading and mixing machine and then dispersed by a pin type sand grinder to obtain a first magnetic solution. Another magnetic coating composition containing a ferromagnetic powder and a solvent of 30 to 50 wt % of the ferromagnetic powder is kneaded by a double-arm open kneader and then dispersed by a pin type sand grinder, and finally dispersed by a disk type sand grinder to obtain a second magnetic coating solution.

Abstract: A magnetic recording medium is disclosed, comprising a nonmagnetic support having thereon plural magnetic layers comprising ferromagnetic particles dispersed in a binder, said ferromagnetic particles consisting of an iron oxide or a cobalt-containing iron oxide, said plural magnetic layers comprising at least an upper magnetic layer and a lower magnetic layer, wherein said upper magnetic layer has a coercive force (Hc) of from 650 to 1000 Oe, a crystallite size of the ferromagnetic particles contained in said upper magnetic layer is less than 500 .ANG. as measured by a X-ray diffraction method, an average length in the long axis of the ferromagnetic particles contained in said upper magnetic layer is from 0.1 microns to less than 0.25 microns as measured by a transmission type electronmicroscope, said lower magnetic layer has a coercive force (Hc) of from 0.6 to 1.

Abstract: A magnetic recording medium comprises a non-magnetic support having provided thereon a lower magnetic layer having a thickness of 2.5 .mu.m or higher and an upper magnetic layer having a thickness of 2 .mu.m or lower in this order, wherein both the upper and lower magnetic layers contain ferromagnetic particles, and the lower magnetic layer contains carbon black having an average primary particle diameter of less than 20 .mu.m in the amount of from 1.0 to 20 parts by weight per 100 parts by weight of the ferromagnetic particles contained in the lower magnetic layer, and the upper magnetic layer contains carbon black having an average primary particle diameter of at least 40 .mu.m but less than 80 .mu.m in an amount of from 0.1 to 10.0 parts by weight per 100 parts by weight of the ferromagnetic particles contained in the upper magnetic layer, but less than the amount of carbon black used in the lower magnetic layer.

Abstract: An improved magnetic recording medium comprises a nonmagnetic support and a magnetic recording layer which comprises a ferromagnetic powder, a lubricant and an abrasive dispersed in a binder comprising a specific polyurethane resin and a specific vinyl chloride copolymer at a ratio (polyurethane resin:vinyl chloride copolymer) in the range of 15:85 to 90:10. The polyurethane resin has a polar group such as --COOM, --SO.sub.3 M, --OSO.sub.3 M and --PO(OM').sub.2, wherein M is hydrogen or an alkali metal atom, and M' is hydrogen, an alkali metal atom or a lower hydrocarbon group, one polar group being contained per 53,000 to 100,000 of the number-average molecular weight of the resin, and the vinyl chloride copolymer has one of the above-mentioned polar group, one polar group unit being contained per 10,000 to 100,000 of the number-average molecular weight of the copolymer.

Abstract: A magnetic recording medium is described, comprising a nonmagnetic support having thereon a single magnetic layer or plural magnetic layers containing ferromagnetic particles dispersed in a binder, wherein said ferromagnetic particles are ferromagnetic particles of the magnetic iron oxide type having an adsorption amount of stearic acid of from 3.times.10.sup.-6 to 6.times.10.sup.-6 mol/m.sup.2 per a surface area thereof; said binder contains at least one polymer having at least one polar group selected from the group consisting of --SO.sub.3 M, --OSO.sub.3 M, --OPO(OM').sub.2, --COOM and --PO(OM').sub.2, in which M represents Na, Li, K, a hydrogen atom, NR.sub.4 or NHR.sub.3, M' represents Na, Li, K, a hydrogen atom, NR.sub.4, NHR.sub.3 or an alkyl group, and R.sub.3 and R.sub.4 represent a lower alkyl group; and said magnetic layer further contains at least one fatty acid.

Abstract: A magnetic recording medium is disclosed, comprising a nonmagnetic support having thereon a lower magnetic layer comprising ferromagnetic particles and binders and an upper magnetic layer comprising ferromagnetic particles and binders in this order, wherein the upper magnetic layer contains (a) an abrasive agent having a Mohs' hardness of 6 or more and an average particle diameter of 0.45 .mu.m or more and (b) an abrasive agent having a Mohs' hardness of 6 or more and an average particle diameter of 0.25 .mu.m or less.

Abstract: A magnetic recording medium is disclosed, which comprises a non-magnetic support having coated thereon a magnetic layer, said non-magnetic support being a film substantially composed of polyethylene terephthalate and having a cutting index (Z) of 6 or less as defined by equation (1):Z=383.3-2.76A-2000B+840.DELTA.n (1)wherein A is the haze value, B is the surface orientation coefficient represented by {(n.sub.MD +n.sub.TD)/2}-n.sub.ZD, n.sub.MD is the refractive index in the machine direction, n.sub.TD is the refractive index in the transverse direction, n.sub.ZD is the refractive index in the thickness direction, and .DELTA.n is the difference of the refractive indices represented by n.sub.MD -n.sub.TD ; and said magnetic layer has yield elongation (L) of 10% or lower and requires energy (E) of 1.0 kg/mm.sup.2 or less to reach the yield point.