CA1167408A - Electron beam curing of magnetic media - Google Patents
Electron beam curing of magnetic mediaInfo
- Publication number
- CA1167408A CA1167408A CA000385988A CA385988A CA1167408A CA 1167408 A CA1167408 A CA 1167408A CA 000385988 A CA000385988 A CA 000385988A CA 385988 A CA385988 A CA 385988A CA 1167408 A CA1167408 A CA 1167408A
- Authority
- CA
- Canada
- Prior art keywords
- radiation
- acrylated
- molecular weight
- magnetic
- polymer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F299/00—Macromolecular compounds obtained by interreacting polymers involving only carbon-to-carbon unsaturated bond reactions, in the absence of non-macromolecular monomers
- C08F299/02—Macromolecular compounds obtained by interreacting polymers involving only carbon-to-carbon unsaturated bond reactions, in the absence of non-macromolecular monomers from unsaturated polycondensates
- C08F299/022—Macromolecular compounds obtained by interreacting polymers involving only carbon-to-carbon unsaturated bond reactions, in the absence of non-macromolecular monomers from unsaturated polycondensates from polycondensates with side or terminal unsaturations
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/62—Record carriers characterised by the selection of the material
- G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
- G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
- G11B5/702—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the bonding agent
- G11B5/7021—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the bonding agent containing a polyurethane or a polyisocyanate
- G11B5/7022—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the bonding agent containing a polyurethane or a polyisocyanate containing mixtures of polyurethanes or polyisocyanates with other polymers
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/62—Record carriers characterised by the selection of the material
- G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
- G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
- G11B5/702—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the bonding agent
- G11B5/7023—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the bonding agent containing polyesters, polyethers, silicones, polyvinyl resins, polyacrylresins or epoxy resins
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/62—Record carriers characterised by the selection of the material
- G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
- G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
- G11B5/702—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the bonding agent
- G11B5/7026—Radiation curable polymers
Abstract
RADIATION-CURED MAGNETIC MEDIA
AND PROCESS FOR MAKING SAME
ABSTRACT
A magnetic media having improved mechanical and magnetic properties comprising a nonmagnetic sub-strate coated with a magnetic binder composition composed of (a) a radiation-cured mixture of a high molecular weight thermoplastic polymer, such as a linear polyurethane of MW greater than 50,000, and a radiation-curable polyfunctional acrylate prepolymer and (b) magnetic particles dispersed in the radiation-cured mixture.
AND PROCESS FOR MAKING SAME
ABSTRACT
A magnetic media having improved mechanical and magnetic properties comprising a nonmagnetic sub-strate coated with a magnetic binder composition composed of (a) a radiation-cured mixture of a high molecular weight thermoplastic polymer, such as a linear polyurethane of MW greater than 50,000, and a radiation-curable polyfunctional acrylate prepolymer and (b) magnetic particles dispersed in the radiation-cured mixture.
Description
RADIATION-CURED MAGNE~IC
MEDIA AND PROCESS FO~ MAKING_SAME
DESCRIPTION
Technical Field The invention relates to electron beam (~B) cuxed magnetic recording media and to a process or making such media.
Background Art Magnetic media are composed of a nonmagnetic substrate or support coated with a cured resin binder containing dispersed finely divided magnetic partic-lesO Normally the backing is made of plastic although other materials such as paper, glass, or metal can be used. Such magnetic media are ordinarily in the form of a tape, belt, disc or the like. In this regard the word "tape" is frequently used hereinafter to generic-ally denote such media since tape is the most common form v magnetic recording media. It will be under-stood, however, that all forms of magnetic media are included within the scope of this invention.
The binders used in tape are typically curable high molecular weight thermoplastic polymers.
These binders are usually cured in the fluid state with a chemical curing agent such as a diisocyanate. The curing process causes crosslinking of the thermoplastic polymer chains as well as other reactions involving the diisocyanate.
674~3~
Chemical curing of tape binders has disadvan-tages and drawbacks. The curing reaction is generally -- unpredictable and i5 highly sensitive to temperature variations, moisture, and stoichiometry. More impor s tantly it generally provides a cured binder having a lower than desired crosslink density~ It also results in the curing agent being incorporated into the binder, which agent does not directly contribute to the magnet-ic or mechanical properties of the tape. Furthermore, as compared to the EB curing process of the present in--vention it requires more solvent and is more time con-suming. Also, electron beam curing can bring about as~
ymmetric curin~ of the magnetic binder coating wherein there is a crosslink density gradient across the coat-lS ing thickness. Such curing cannot be achieved withchemical curing.
Radiation-induced curing of tape binders has ; also been suggested in the literature. US Pat No 3104983 teaches curing butadiene-acrylonitrile tape binders with subatomic radiation. The present applic-ants have found, however, that EB-cured hutadiene-a-crylonitrile copolymer exhibits little crosslinking relative to applicants' binder~ Japanese pa~ent pub-lication no. 12423 (1972) describes an EB-cured ~5 magnetic tape in which the binder is composed of an acrylate-methacrylate addition polymer that contains no rective acrylate groups and an acrylate or dimethacryl-ate monomer. The only component of this binder that is ~- suscep~ible to EB-curing is the monomerO It is believed that the properties of such tapes will be relatively inferior due, among other things~ to the presence of methacrylate polymers which are known to preferentially degrade when expo~ed to radiation.
. .
A prime object of the present invention is to provide an EB-cured magnetic recording media having improved magnetic and mechanical properties as compared to the prior chemically cured or radiation-cured mag-netic media. Another object is to provide a process for making such media that involves no chemical curing agents such as diisocyanates.
Disclosure of the Invention ; One aspect of the invention is a magnetic medium comprising a nonmagnetic substrate coated with a radiation-cured polymeric binder having magnetic par-ticles dispersed therein characterized in that the binder comprises a radiation-cured mixture of a high molecular weight thermoplastic polymer and a radiation-curable acrylate prepo~ymer.
A second aspect of the invention is a process for making the above described magnetic medium compri-~ing the steps of preparing a fluid mixture of a solu-tion of a radiation-curable polymeric binder and mag netic particles, coating a nonmagnetic substrate with the fluid mixture, evaporating the solvent from the coating to solidify the coating, calendering the dried coated substrate, and exposing the dried coated substrate to sufficient radiation to cure the coating characterized in that the polymeric binder comprises a mixt~re of a high molecular weight thermoplastic polymer and a radiation-curable acrylate prepolymer.
:;
-~ Brief Description of_the Drawings .
Figure l is a block diagram showing the manu-facture of a magnetic tape according to the process of .:
the present invention.
4~13 Figure 2 is a si~e view of a coating and curing line wherein the curing is clone by means of an electron beam.
Modes o Car~ in Out the Invention , Y g _ _ _ The principal polymeric component of the mag-netic binder composition in terms of quanitity is a high molecular weight thermopla~tic polymer. This component is essential to obtaining a magnetic medium having appropriate mechanical properties. These poly-mers are typically linear ully polymerized homopoly-mers or copolymers havi~g a weight average molecular weight of at least about 50,000, usually in the range 100lO00 to 800,000 and more usually 100,000 to 300,000. Examples of such polymers are styrene-butadiene copolymers, acrylonitrile-butadiene-copolymers r vinylacetate-vinylchloride copolymers, polyesters, polyamides, polycarbonates, polysulfones, polyacrylates, polyacrylic acid, polyvinylacetal, polyvinylbutyral, polyurethanes, and epoxy and phenoxy resinsO Polyurethanes, both polyesterurethanes and polyetherurethanes, are a preferred class of high molecular weight thermoplastic polymers.
The other essential polymeric component of the magnetic binder is a radiation-curable acrylic prepolymer. As used herein the term "prepolymer" de-notes low molecular weight partially polymerized mole-cules, including molecules commonly called oligomers.
These prepolymeræ are preferably polyfunctional, that is, they contain more than one reactive acrylate group. Difunctional and triunctional acrylate pre polymers are particularly pre~erred. Their weight average molecular weight will usually be less than about lO,000, more usually less than 5,000. They ~ 7'~8 : -5~
are susceptible to rapid radiation-induced crosslinking using either nonparticulate ~ultraviolet, X-ray, or ~ gamma) radiation or particulate ( a -particles, : electrons, ~-particles, protons) radiation~ Electron beam radiation is preferred because i~s generation, focussing, and shielding ar~ simple relative to other forms of radiation. Examples of EB-curable acrylate prepolymers that may be used in the mixture are acrylated epoxy resins, acrylated urethanes, acrylated 10 alkyd urethanes, acrylated polycaprolactams, acrylated polyethers, acrylated unsaturated acid modified drying oils, and acrylated polyesters. Specific examples of such prepolymers are :
: 15 l. Epoxy/Acrylate CH2-cH-cl-[o~cH2~m]n~~cH2-clH-cH2-o-~-c-~-Olp-cH2-fH-cH2 !~ ~ : HO CH 3 OH
. . .
20 _[o-~CH2)m]nO-ll-cH=cH2 ~,, . O
. 2. Pol~ester/Ur hane/Acrylate CH2=cH-lc~-[o-(cH2)m]no-cl-NH~ 1H-C~
~; 25 O CH3 O
: .
-[DO-AD]p-OO-c-NH-l-NH_lCl_[o-(c~2)m]n-o-s-cH=cH2 3. Polyether Acrylate CH2=CH-C-0 ~CH2-CH-OI pfi-CH=CH2 . O CH3 O
/
,~ .
~6--4~ Polyester/Acrylate CH2=CH-C O(cH2)6[o~-(cH2)~ o_(cH2)6]poc C 2 O O O O
wherein m = 1, 2, 3 n = 0, 1 (preferably 0) p = 1, 2, 3 (preferably 1) DO = 1,6-Hexanediol AD = adipic acid ~= Phenyl or substituted phenyl The ratio of the high molecular weiqht thermoplastic polymer to the acrylate prepolymer in the mixture can vary from 50:50 to 90:10 and is preferably in the range of 60:4Q to 8Q:20 on a resin solids basis by weight. In other words the acrylate prepolymer can be from as little as 10~ to as much as 50~ of the total polymer in the binder.
Minor amounts of other conventional additives may be included in the magnetic binder composition if desired. Examples of such a~ditives are: dispersants such as lecithin, organic esters of phosphoric acid, quaternary ammonium compounds, and other suractants to aid in the deagglomeration and dispersal of the magnet-ic particles; conductive pigments, such as conductive carbon black, to reduce the electrical resistivity of the tape; and lubricants to minimize head-tape friction. The inclusion of materials, such as ~
methacrylate polymers, that are preferentially degraded by radiation should be avoided. As indicated above, the binder cQntains no chemical curing a~ent. L
~9L6~7~
The third essential ingredient in the magnet-ic binder is finely divided magnetic particle~ Examp-les of magnetic particles that are commonly used are ~( ferric oxides, doped iron oxides, chromium dioxide, and elemental iron, cobalt and/or nickeL. Acicular ~ ferric oxide is most commonly usedl Particle size should be such as to obtain a good dispersion of the magnetic component in the mixture. The particle length of the ~ ferric oxide will ~sually be in the range of `10 0.2 to 1 ~ m and it will usually have an aspect ratio of 5:1 to 10:1. It will normally constitute about 60%
to about 90% by weight of the ~.agnetic binder composition after drying.
In order to disperse the magnetic particles and apply the magnetic binder composition as a thin coating to the nonmagnetic film substrate the polymeric components are dissolved in a common solvent such as tetrahydrofuran, cylcohexanoner methyl ethyl ketone, toluene, and methyl isobutyl ketone that will evaporate rapidly. The polymer concentration in the solution will typically be in the range o 0.05 to 0.20 mg/ml~
This solution, containing the homogeneously dispersed magnetic particles, is applied to the magnetic substrate using conventional coating machinery at a thickness in the range of about 2.5 to 15 ~m. After the coating is applied, the coated substrate is dried to evaporate off the solvent leaving a solid coating that is dry to the touch.
After the solvent is evaporated from the '''! 30 coating the coated substrate is calendered and then exposed to radiation of sufficient energy and dose to cure the magnetic binder composition. The strength of the radiation will depend upon a number of factors such as the percentage of the acrylate prepolymer in the zoating, the activity or crosslinkability of the acrylate prepolymer, the thickness of the coating and the duration of exposure. As indicated above, electron beam radiation is preferred. UV radiation is the least desirable since its use will normally require inclusion of photoinitiators in the binder an~ it is highly absorbed by additives such as pigments. Preferably, an electron beam energy of no more than 300 KeV is employ-ed since higher energies do not result in a better cure of the binder and may cause damage to many magnetic tape substrate materials. The dose can vary from 1 to 15 Mrad.
The chemical reactions that occur during the curing are primarily radiation-induced free radical reaction~, the most important of which are the direct crosslinking of high molecular weight thermoplastic polymer chains via hydrogen abstraction from the chains and crosslinking of those chains via polyfunctional prepolymer links. Other competing reactions are addi-tion polymerization of the prepolymer molecules and grating of the prepolymer molecules onto the thermo-plastic polymer chains. These reactions result in an EB-cured tape that has improved mechanical properties as compared to prior tapes.
Referring now to the drawings, Figure 1 shows the general plan for manufacturing a magnetic tape u-tilizing the present invention. Although this partic-ular figure shows the manufacture of a tape, it is ob-vious that the same technique could be used to manufac-ture other magnetic media by making suitable modiica-tions as are well-known to those skilled in the art.
At 3, a coating mixture is prepared as is later de-scribed in the examples. This mixture is then coated at 5 on a tape utilizing well-known tape coating tech~
nlques. Before the tape has dried, it is ordinarily oriented as at 7 by passing it through a strong magnetic ield. At 9 the tape is passed through a conventional drying oven which may be followed by S burnishing or similar operations. The tape is then calendered at 11 and at this point the tape is dry, i.e. the binder is in a solid, thermoplastic state.
The tape is now passed through an electron beam curing apparatus at 13 wherein the crosslinking reaction(s) take place. The tape may then be slit at 15, burnished at 17 and then spooled at 13. All of these operations are conventional in the tape makin~ field and are well-known to those skilled in the art except step 13 which consists of passing a tape through a device wherein it is exposed to an electron beam.
Figure 2 shows a typical election beam curing process wherein an electron beam generator 21 is provi-ded with suitable shielding 23 and ~5. The tape is passed under the generator 21 and between the shields 23 and ~5 so that the electron beam 29 impinges on the tape.
As is mentioned above, applicants' EB-cured binder exhibits much more crosslinking than EB-cured prior art binders. In order to demonstra~e ~his a number of films of diferent polymers were prepared and the elastic modulus was tested before and after being subjected to an electron beam treatment. The elastic modulus of the free film is used here as a measure to reflect the crosslinkability or extent of crosslinking - 30 of a polymer when subjected to an electron beam. Ex-ample 1 shows the results which were obtained.
:; .
7~
Example l--Elastic Modulus of the Free Film EB Elastic Sample Dosage Modulus - No. Film_Composition _ (Mrad) (X104 kPa) lA Phenoxy resin 0 212 lB " 5 lgO
2A Butadiene-Acrylonitrile 0 0.17 copolymer 2B " ~ 5 0.21 3A Polyurethane (Estane 5701~Fl)l 0 3.08 3B " 5 3.12 4A EB curable acrylate prepolymer 0 0c45 (Celred 36001~ 50~ and poly-urethane (Estane~5701-Fl) 50%
4B " 5 59.1 1~ A linear polyesterurethane which is sold by B.F. Goodrich. Its properties are:
Typical ASTM
i 20 Value No.
Specific Gravity 1.20 D12-27 Hardness, Durometer 87 D-676 Tensile Strength (kPa)52,000 D-412 .~ Modulus at 30~ Elongation (kPa) 10,300 D-412 ~' ` 25 Elongation (%) 575 Graves Tear (g/cm) 62,000 D-624 . Low-Temperature Brittleness Freeze Point (C) -62 D 746 . Ge~man Low-Temperature .~ : 30 Freeze Point (C) -28 D-1053 ~- Taber Abrasion (mg loss) (CS17 Wheel, 1000 g weight, 5000 cycles)5 D1044-49T
Processing Stock Temperature (C) 171 ., .
i7~
MEDIA AND PROCESS FO~ MAKING_SAME
DESCRIPTION
Technical Field The invention relates to electron beam (~B) cuxed magnetic recording media and to a process or making such media.
Background Art Magnetic media are composed of a nonmagnetic substrate or support coated with a cured resin binder containing dispersed finely divided magnetic partic-lesO Normally the backing is made of plastic although other materials such as paper, glass, or metal can be used. Such magnetic media are ordinarily in the form of a tape, belt, disc or the like. In this regard the word "tape" is frequently used hereinafter to generic-ally denote such media since tape is the most common form v magnetic recording media. It will be under-stood, however, that all forms of magnetic media are included within the scope of this invention.
The binders used in tape are typically curable high molecular weight thermoplastic polymers.
These binders are usually cured in the fluid state with a chemical curing agent such as a diisocyanate. The curing process causes crosslinking of the thermoplastic polymer chains as well as other reactions involving the diisocyanate.
674~3~
Chemical curing of tape binders has disadvan-tages and drawbacks. The curing reaction is generally -- unpredictable and i5 highly sensitive to temperature variations, moisture, and stoichiometry. More impor s tantly it generally provides a cured binder having a lower than desired crosslink density~ It also results in the curing agent being incorporated into the binder, which agent does not directly contribute to the magnet-ic or mechanical properties of the tape. Furthermore, as compared to the EB curing process of the present in--vention it requires more solvent and is more time con-suming. Also, electron beam curing can bring about as~
ymmetric curin~ of the magnetic binder coating wherein there is a crosslink density gradient across the coat-lS ing thickness. Such curing cannot be achieved withchemical curing.
Radiation-induced curing of tape binders has ; also been suggested in the literature. US Pat No 3104983 teaches curing butadiene-acrylonitrile tape binders with subatomic radiation. The present applic-ants have found, however, that EB-cured hutadiene-a-crylonitrile copolymer exhibits little crosslinking relative to applicants' binder~ Japanese pa~ent pub-lication no. 12423 (1972) describes an EB-cured ~5 magnetic tape in which the binder is composed of an acrylate-methacrylate addition polymer that contains no rective acrylate groups and an acrylate or dimethacryl-ate monomer. The only component of this binder that is ~- suscep~ible to EB-curing is the monomerO It is believed that the properties of such tapes will be relatively inferior due, among other things~ to the presence of methacrylate polymers which are known to preferentially degrade when expo~ed to radiation.
. .
A prime object of the present invention is to provide an EB-cured magnetic recording media having improved magnetic and mechanical properties as compared to the prior chemically cured or radiation-cured mag-netic media. Another object is to provide a process for making such media that involves no chemical curing agents such as diisocyanates.
Disclosure of the Invention ; One aspect of the invention is a magnetic medium comprising a nonmagnetic substrate coated with a radiation-cured polymeric binder having magnetic par-ticles dispersed therein characterized in that the binder comprises a radiation-cured mixture of a high molecular weight thermoplastic polymer and a radiation-curable acrylate prepo~ymer.
A second aspect of the invention is a process for making the above described magnetic medium compri-~ing the steps of preparing a fluid mixture of a solu-tion of a radiation-curable polymeric binder and mag netic particles, coating a nonmagnetic substrate with the fluid mixture, evaporating the solvent from the coating to solidify the coating, calendering the dried coated substrate, and exposing the dried coated substrate to sufficient radiation to cure the coating characterized in that the polymeric binder comprises a mixt~re of a high molecular weight thermoplastic polymer and a radiation-curable acrylate prepolymer.
:;
-~ Brief Description of_the Drawings .
Figure l is a block diagram showing the manu-facture of a magnetic tape according to the process of .:
the present invention.
4~13 Figure 2 is a si~e view of a coating and curing line wherein the curing is clone by means of an electron beam.
Modes o Car~ in Out the Invention , Y g _ _ _ The principal polymeric component of the mag-netic binder composition in terms of quanitity is a high molecular weight thermopla~tic polymer. This component is essential to obtaining a magnetic medium having appropriate mechanical properties. These poly-mers are typically linear ully polymerized homopoly-mers or copolymers havi~g a weight average molecular weight of at least about 50,000, usually in the range 100lO00 to 800,000 and more usually 100,000 to 300,000. Examples of such polymers are styrene-butadiene copolymers, acrylonitrile-butadiene-copolymers r vinylacetate-vinylchloride copolymers, polyesters, polyamides, polycarbonates, polysulfones, polyacrylates, polyacrylic acid, polyvinylacetal, polyvinylbutyral, polyurethanes, and epoxy and phenoxy resinsO Polyurethanes, both polyesterurethanes and polyetherurethanes, are a preferred class of high molecular weight thermoplastic polymers.
The other essential polymeric component of the magnetic binder is a radiation-curable acrylic prepolymer. As used herein the term "prepolymer" de-notes low molecular weight partially polymerized mole-cules, including molecules commonly called oligomers.
These prepolymeræ are preferably polyfunctional, that is, they contain more than one reactive acrylate group. Difunctional and triunctional acrylate pre polymers are particularly pre~erred. Their weight average molecular weight will usually be less than about lO,000, more usually less than 5,000. They ~ 7'~8 : -5~
are susceptible to rapid radiation-induced crosslinking using either nonparticulate ~ultraviolet, X-ray, or ~ gamma) radiation or particulate ( a -particles, : electrons, ~-particles, protons) radiation~ Electron beam radiation is preferred because i~s generation, focussing, and shielding ar~ simple relative to other forms of radiation. Examples of EB-curable acrylate prepolymers that may be used in the mixture are acrylated epoxy resins, acrylated urethanes, acrylated 10 alkyd urethanes, acrylated polycaprolactams, acrylated polyethers, acrylated unsaturated acid modified drying oils, and acrylated polyesters. Specific examples of such prepolymers are :
: 15 l. Epoxy/Acrylate CH2-cH-cl-[o~cH2~m]n~~cH2-clH-cH2-o-~-c-~-Olp-cH2-fH-cH2 !~ ~ : HO CH 3 OH
. . .
20 _[o-~CH2)m]nO-ll-cH=cH2 ~,, . O
. 2. Pol~ester/Ur hane/Acrylate CH2=cH-lc~-[o-(cH2)m]no-cl-NH~ 1H-C~
~; 25 O CH3 O
: .
-[DO-AD]p-OO-c-NH-l-NH_lCl_[o-(c~2)m]n-o-s-cH=cH2 3. Polyether Acrylate CH2=CH-C-0 ~CH2-CH-OI pfi-CH=CH2 . O CH3 O
/
,~ .
~6--4~ Polyester/Acrylate CH2=CH-C O(cH2)6[o~-(cH2)~ o_(cH2)6]poc C 2 O O O O
wherein m = 1, 2, 3 n = 0, 1 (preferably 0) p = 1, 2, 3 (preferably 1) DO = 1,6-Hexanediol AD = adipic acid ~= Phenyl or substituted phenyl The ratio of the high molecular weiqht thermoplastic polymer to the acrylate prepolymer in the mixture can vary from 50:50 to 90:10 and is preferably in the range of 60:4Q to 8Q:20 on a resin solids basis by weight. In other words the acrylate prepolymer can be from as little as 10~ to as much as 50~ of the total polymer in the binder.
Minor amounts of other conventional additives may be included in the magnetic binder composition if desired. Examples of such a~ditives are: dispersants such as lecithin, organic esters of phosphoric acid, quaternary ammonium compounds, and other suractants to aid in the deagglomeration and dispersal of the magnet-ic particles; conductive pigments, such as conductive carbon black, to reduce the electrical resistivity of the tape; and lubricants to minimize head-tape friction. The inclusion of materials, such as ~
methacrylate polymers, that are preferentially degraded by radiation should be avoided. As indicated above, the binder cQntains no chemical curing a~ent. L
~9L6~7~
The third essential ingredient in the magnet-ic binder is finely divided magnetic particle~ Examp-les of magnetic particles that are commonly used are ~( ferric oxides, doped iron oxides, chromium dioxide, and elemental iron, cobalt and/or nickeL. Acicular ~ ferric oxide is most commonly usedl Particle size should be such as to obtain a good dispersion of the magnetic component in the mixture. The particle length of the ~ ferric oxide will ~sually be in the range of `10 0.2 to 1 ~ m and it will usually have an aspect ratio of 5:1 to 10:1. It will normally constitute about 60%
to about 90% by weight of the ~.agnetic binder composition after drying.
In order to disperse the magnetic particles and apply the magnetic binder composition as a thin coating to the nonmagnetic film substrate the polymeric components are dissolved in a common solvent such as tetrahydrofuran, cylcohexanoner methyl ethyl ketone, toluene, and methyl isobutyl ketone that will evaporate rapidly. The polymer concentration in the solution will typically be in the range o 0.05 to 0.20 mg/ml~
This solution, containing the homogeneously dispersed magnetic particles, is applied to the magnetic substrate using conventional coating machinery at a thickness in the range of about 2.5 to 15 ~m. After the coating is applied, the coated substrate is dried to evaporate off the solvent leaving a solid coating that is dry to the touch.
After the solvent is evaporated from the '''! 30 coating the coated substrate is calendered and then exposed to radiation of sufficient energy and dose to cure the magnetic binder composition. The strength of the radiation will depend upon a number of factors such as the percentage of the acrylate prepolymer in the zoating, the activity or crosslinkability of the acrylate prepolymer, the thickness of the coating and the duration of exposure. As indicated above, electron beam radiation is preferred. UV radiation is the least desirable since its use will normally require inclusion of photoinitiators in the binder an~ it is highly absorbed by additives such as pigments. Preferably, an electron beam energy of no more than 300 KeV is employ-ed since higher energies do not result in a better cure of the binder and may cause damage to many magnetic tape substrate materials. The dose can vary from 1 to 15 Mrad.
The chemical reactions that occur during the curing are primarily radiation-induced free radical reaction~, the most important of which are the direct crosslinking of high molecular weight thermoplastic polymer chains via hydrogen abstraction from the chains and crosslinking of those chains via polyfunctional prepolymer links. Other competing reactions are addi-tion polymerization of the prepolymer molecules and grating of the prepolymer molecules onto the thermo-plastic polymer chains. These reactions result in an EB-cured tape that has improved mechanical properties as compared to prior tapes.
Referring now to the drawings, Figure 1 shows the general plan for manufacturing a magnetic tape u-tilizing the present invention. Although this partic-ular figure shows the manufacture of a tape, it is ob-vious that the same technique could be used to manufac-ture other magnetic media by making suitable modiica-tions as are well-known to those skilled in the art.
At 3, a coating mixture is prepared as is later de-scribed in the examples. This mixture is then coated at 5 on a tape utilizing well-known tape coating tech~
nlques. Before the tape has dried, it is ordinarily oriented as at 7 by passing it through a strong magnetic ield. At 9 the tape is passed through a conventional drying oven which may be followed by S burnishing or similar operations. The tape is then calendered at 11 and at this point the tape is dry, i.e. the binder is in a solid, thermoplastic state.
The tape is now passed through an electron beam curing apparatus at 13 wherein the crosslinking reaction(s) take place. The tape may then be slit at 15, burnished at 17 and then spooled at 13. All of these operations are conventional in the tape makin~ field and are well-known to those skilled in the art except step 13 which consists of passing a tape through a device wherein it is exposed to an electron beam.
Figure 2 shows a typical election beam curing process wherein an electron beam generator 21 is provi-ded with suitable shielding 23 and ~5. The tape is passed under the generator 21 and between the shields 23 and ~5 so that the electron beam 29 impinges on the tape.
As is mentioned above, applicants' EB-cured binder exhibits much more crosslinking than EB-cured prior art binders. In order to demonstra~e ~his a number of films of diferent polymers were prepared and the elastic modulus was tested before and after being subjected to an electron beam treatment. The elastic modulus of the free film is used here as a measure to reflect the crosslinkability or extent of crosslinking - 30 of a polymer when subjected to an electron beam. Ex-ample 1 shows the results which were obtained.
:; .
7~
Example l--Elastic Modulus of the Free Film EB Elastic Sample Dosage Modulus - No. Film_Composition _ (Mrad) (X104 kPa) lA Phenoxy resin 0 212 lB " 5 lgO
2A Butadiene-Acrylonitrile 0 0.17 copolymer 2B " ~ 5 0.21 3A Polyurethane (Estane 5701~Fl)l 0 3.08 3B " 5 3.12 4A EB curable acrylate prepolymer 0 0c45 (Celred 36001~ 50~ and poly-urethane (Estane~5701-Fl) 50%
4B " 5 59.1 1~ A linear polyesterurethane which is sold by B.F. Goodrich. Its properties are:
Typical ASTM
i 20 Value No.
Specific Gravity 1.20 D12-27 Hardness, Durometer 87 D-676 Tensile Strength (kPa)52,000 D-412 .~ Modulus at 30~ Elongation (kPa) 10,300 D-412 ~' ` 25 Elongation (%) 575 Graves Tear (g/cm) 62,000 D-624 . Low-Temperature Brittleness Freeze Point (C) -62 D 746 . Ge~man Low-Temperature .~ : 30 Freeze Point (C) -28 D-1053 ~- Taber Abrasion (mg loss) (CS17 Wheel, 1000 g weight, 5000 cycles)5 D1044-49T
Processing Stock Temperature (C) 171 ., .
i7~
2. A fast curing diacrylate ester of a bisphenol A type epoxy resin which is sold hy Celanese Chemical Company. Its properties are:
.
Visco~ity @ 25QC (cps) 250,000 Density g/cc 1.18 % Free acrylic acid 5 maximum Gardner color 0.1 Flash point (C) >90 ` % Active 100 Hydroxyl value 200 It can be seen from the above that conven-tional tape binders such as phenoxy resins, butadiene-acry}onitrile copolymers and polyurethane resins under-wen~ little change when being subjected to an electron beam, while a composition made in accordance with the present invention, as is shown in samples 4A and 4B
wherein 50% of an acrylate prepolymer was used in combination with the high molecular weight resin, :20 underwent a very dra~tic change in elastic modulus.
Example 2--Formulation of EB-cured Scm Video Tape Into a jar mill containing just enough one cm steel balls to be covered by the ingredient solution, was . added the:following ingredients:
1515 gm of acicular ~ ferric oxide 7.8 gm of alumina powder 6201 gm of carbon black ~: 43~4 gm of lecithin 31.9 ym of melamine type resin 12.4 gm of butoxyethyl stearate 71.1 gm of Estane 5714-Fl pol~urethane3 290 gm of methyl ethyl ketone 290 gm of tetrahydrofuran 680 gm of cyclohexanone
.
Visco~ity @ 25QC (cps) 250,000 Density g/cc 1.18 % Free acrylic acid 5 maximum Gardner color 0.1 Flash point (C) >90 ` % Active 100 Hydroxyl value 200 It can be seen from the above that conven-tional tape binders such as phenoxy resins, butadiene-acry}onitrile copolymers and polyurethane resins under-wen~ little change when being subjected to an electron beam, while a composition made in accordance with the present invention, as is shown in samples 4A and 4B
wherein 50% of an acrylate prepolymer was used in combination with the high molecular weight resin, :20 underwent a very dra~tic change in elastic modulus.
Example 2--Formulation of EB-cured Scm Video Tape Into a jar mill containing just enough one cm steel balls to be covered by the ingredient solution, was . added the:following ingredients:
1515 gm of acicular ~ ferric oxide 7.8 gm of alumina powder 6201 gm of carbon black ~: 43~4 gm of lecithin 31.9 ym of melamine type resin 12.4 gm of butoxyethyl stearate 71.1 gm of Estane 5714-Fl pol~urethane3 290 gm of methyl ethyl ketone 290 gm of tetrahydrofuran 680 gm of cyclohexanone
3. This polyurethane is a member of a family of polyurethane resins which are made by reacting p,p'-diphenylmethane diisocyanate, adipic acid and butanediol-1,4 in such proportions that all of the 0 isocyanate groups have reacted to give a substantially unreactive polymer. It is sold by B.F. Goodrich and has the following characteristics:
Specific Gravity................................... 1.21 Hardness (Durometer A)~ .88 Tensile Strength at 23~C (kPa)................ ~. 40,000 300% modulus at 23C (kPa)..................... O~ 8,500 Taber abrasion resistance (gram loss--CS17 wheel, 1000 gr/wheel 500 rev.)................. 0.0024 The above ingredients were milled for 48 hours, and after which was added a solu~ion containing the following ingredients:
130 gm of Estane 5714-Fl 85.5 gm of EB-curable acrylate prepolymer (Celred 3701)4 220 gm of tetrahydrofuran ,, :! 210 gm of cyclohexanone 410 gm of methyl ethyl ketone
Specific Gravity................................... 1.21 Hardness (Durometer A)~ .88 Tensile Strength at 23~C (kPa)................ ~. 40,000 300% modulus at 23C (kPa)..................... O~ 8,500 Taber abrasion resistance (gram loss--CS17 wheel, 1000 gr/wheel 500 rev.)................. 0.0024 The above ingredients were milled for 48 hours, and after which was added a solu~ion containing the following ingredients:
130 gm of Estane 5714-Fl 85.5 gm of EB-curable acrylate prepolymer (Celred 3701)4 220 gm of tetrahydrofuran ,, :! 210 gm of cyclohexanone 410 gm of methyl ethyl ketone
4. A nonvolatile diacrylate ester of a bisphenol A epoxy resin, which is sold by Celanese Chemical Company. Its typical properties are listed below:
Viscosity @ 25C (cps)850,000 Density, g/cc 1.2 Free Acrylic AcidLess than 1%
Hydroxyl Value 232 Color 5 maximum Flash point ~C) 90 After ~he addition, the final mix was then milled or an additional six hours, followed by separa-tions, filtration, coating, drying, calendering ana elec~ron beam curing at a dose of 10 Mrad.
Utilizing the same general procedures as outlined in Fxample 2 and the standar~ procedure of sandmilling, additional magnetic media were made and tested as follows:
Example 3--Hlgher Output of EB-cured High Energy Instrumentation Tape Binder Compasition G162-71 polyure~hane stan 5701 Fl)/halogenated polymer (Ratio: 75/25) G162-84A polyur ~ hane/EB-curable acrylate prepolymer (Estan ~ 5701-Fl/Celred 3600) (Ratio: 60/4~) G162-84B polyur~hane/EB-curable acrylate prepolymer (Estane 5701-Fl/(Chempol acrylate prepolymer)5 (~atio: 60/40)
Viscosity @ 25C (cps)850,000 Density, g/cc 1.2 Free Acrylic AcidLess than 1%
Hydroxyl Value 232 Color 5 maximum Flash point ~C) 90 After ~he addition, the final mix was then milled or an additional six hours, followed by separa-tions, filtration, coating, drying, calendering ana elec~ron beam curing at a dose of 10 Mrad.
Utilizing the same general procedures as outlined in Fxample 2 and the standar~ procedure of sandmilling, additional magnetic media were made and tested as follows:
Example 3--Hlgher Output of EB-cured High Energy Instrumentation Tape Binder Compasition G162-71 polyure~hane stan 5701 Fl)/halogenated polymer (Ratio: 75/25) G162-84A polyur ~ hane/EB-curable acrylate prepolymer (Estan ~ 5701-Fl/Celred 3600) (Ratio: 60/4~) G162-84B polyur~hane/EB-curable acrylate prepolymer (Estane 5701-Fl/(Chempol acrylate prepolymer)5 (~atio: 60/40)
5. A solvent-free epoxyacrylate re~in which contains active acrylic unsaturation in the polymer molecule. It i5 sold by Freeman Company and has the - following properties:
Polymer solids, % by weight..... O................... ~. loa Reactive monomer, % by weight........... ........... none UV Photoinitiator, % by weight.. ~....... .~..................... none Acid number.... ~.O................................ 3-10 ` Color.......... O.............. ...... 1-4 Viscocity as supplied, Centipoise....... 4000 6000 at 60C
10 ' Density g/cc...O...... 1400-1800 at 70C
1.17-1.20 Output6 dB ~ indicated CuringFrequency (MHz) Binder Method` 0.2 1.0 1.5 2.0 - ___ _ G162~71 chemical +1.4 +1.3 ~1.6 +1.9 G162-84A EB curing ~2.0 ~3.0 ~3.5 ~4.9 G162-84B EB curing +1.8 ~2.7 +3.4 +4.0
Polymer solids, % by weight..... O................... ~. loa Reactive monomer, % by weight........... ........... none UV Photoinitiator, % by weight.. ~....... .~..................... none Acid number.... ~.O................................ 3-10 ` Color.......... O.............. ...... 1-4 Viscocity as supplied, Centipoise....... 4000 6000 at 60C
10 ' Density g/cc...O...... 1400-1800 at 70C
1.17-1.20 Output6 dB ~ indicated CuringFrequency (MHz) Binder Method` 0.2 1.0 1.5 2.0 - ___ _ G162~71 chemical +1.4 +1.3 ~1.6 +1.9 G162-84A EB curing ~2.0 ~3.0 ~3.5 ~4.9 G162-84B EB curing +1.8 ~2.7 +3.4 +4.0
6. Output was mea~ured by Ampex ER-2000 at the indicated frequencies. A higher number indicates ~- higher output~ and better tape. The reerence tape was -~ ~emorex 716 tape~
, Example 4--Higher Output o~_EB-Cured_Flop~ Disk - Bin~er _omposition _ _ ~ G162-41 polyure~hane - ~Estan 701 ` :
G162-82C polyurethane/EB-curable acrylate prepolymer (Estane~5701-Fl/Celred 3600) (Ratio: 55/45) A
output7 ~) Binder Curing Method 00-2F 34-2F _00-lF 34-lF
G162-41 chemical 96 94 96 92 G162-82C EB-cured llO 107 115 108
, Example 4--Higher Output o~_EB-Cured_Flop~ Disk - Bin~er _omposition _ _ ~ G162-41 polyure~hane - ~Estan 701 ` :
G162-82C polyurethane/EB-curable acrylate prepolymer (Estane~5701-Fl/Celred 3600) (Ratio: 55/45) A
output7 ~) Binder Curing Method 00-2F 34-2F _00-lF 34-lF
G162-41 chemical 96 94 96 92 G162-82C EB-cured llO 107 115 108
7. The output was measured by 3-Phenix Certifier. The higher the percentage, the better the tape. 100~ was the reference percentage.
Example 5--Better Performance_of _B-cuxed_ _. Vi~
~inder Composition G162 47 polyurethane (Estane~S714-Fl)/phenoxy resin (PKHH~3 (Ratio: 67/33) G162-85C polyurethane (Estane~ 714-Fl)/EB-curable acrylate prepolymer (Celred 3701) ~Ratio: 70/30)
Example 5--Better Performance_of _B-cuxed_ _. Vi~
~inder Composition G162 47 polyurethane (Estane~S714-Fl)/phenoxy resin (PKHH~3 (Ratio: 67/33) G162-85C polyurethane (Estane~ 714-Fl)/EB-curable acrylate prepolymer (Celred 3701) ~Ratio: 70/30)
8. A phenoxy resin made from bis-phenol-A
and epichlorohydrin, sold by Union Carbide Chemical Company under the trade name of Bakelite phenoxy resin -~ PKH~, and having the followin~ properties:
.
j, :
'`'., ' Specîfic Gravity............................ O.... 1.18 Viscosity of 40~ solids in MEK, BrookEield RVF, 20 rp~ NoO 5 spindle,.. ~..~........ ~........... 5,500 to 7,700 cps.
Reduced Viscosity (0~2 g/100 ml dimethylformamide).......... ~Ø4 to 0.6 ~ltimate Tensile Strenyth...................... G2,000 to 65,000 kPa Ultimate Tensile Elongation.................. 50% to 100~
Softening Temperature.............................. 100C
Permeability (25 micron free film at 25C) Water Vapor (24 hrs/645cm2)......s............ 138 g/mm Oxygen (24 hrs/645 cm2)................... ...... 200 to 310 cc/mm Carbon Dioxide (24 hrs/645 cm2)........... ...... 590 to 1180 cc/mm Bulking Value............................... ... 1.18 g/cc Perform nce Chroma Video Binder SNR10 SNRll Dura- Act-Bind- Curing (Ref. (Ref. bilityl2 ivity er Method Gloss 50.0dB) 47.BdB) Detector 47 chemical 74 -1.0 0 2l~40/ 4.0 6.0 85C EB-cured 93 +2.0 +1,0 2'30"/ 1.6 3.0 `- 15~/4
and epichlorohydrin, sold by Union Carbide Chemical Company under the trade name of Bakelite phenoxy resin -~ PKH~, and having the followin~ properties:
.
j, :
'`'., ' Specîfic Gravity............................ O.... 1.18 Viscosity of 40~ solids in MEK, BrookEield RVF, 20 rp~ NoO 5 spindle,.. ~..~........ ~........... 5,500 to 7,700 cps.
Reduced Viscosity (0~2 g/100 ml dimethylformamide).......... ~Ø4 to 0.6 ~ltimate Tensile Strenyth...................... G2,000 to 65,000 kPa Ultimate Tensile Elongation.................. 50% to 100~
Softening Temperature.............................. 100C
Permeability (25 micron free film at 25C) Water Vapor (24 hrs/645cm2)......s............ 138 g/mm Oxygen (24 hrs/645 cm2)................... ...... 200 to 310 cc/mm Carbon Dioxide (24 hrs/645 cm2)........... ...... 590 to 1180 cc/mm Bulking Value............................... ... 1.18 g/cc Perform nce Chroma Video Binder SNR10 SNRll Dura- Act-Bind- Curing (Ref. (Ref. bilityl2 ivity er Method Gloss 50.0dB) 47.BdB) Detector 47 chemical 74 -1.0 0 2l~40/ 4.0 6.0 85C EB-cured 93 +2.0 +1,0 2'30"/ 1.6 3.0 `- 15~/4
9. Gloss reading was used to indicate the smoothness of the tape surface, the higher the reading, the smoother the surface.
~17-
~17-
10. Chroma SNR (signal to noise ratio) was measured by using spectra analyzer; -1.0 means ldB
worse than the referen~e, +200 means 2dB better ~han the reference.
worse than the referen~e, +200 means 2dB better ~han the reference.
11, Video SNR was m~asured by Rhode & Schwaz meter. O means reference/ +1~0 means 1.0 dB better than reference.
12. Binder durability was measured by Ampex 1st Number represents the time length of measurement, e.g~ 2'; measured for 2 minutes 2'30" measured for 2-1/2 minutes 2nd Number represents percentage shed on the head 3rd Number represents percentage shed on the drum 4th Number represents general rating 1-10, lower the number, the betterO
. 13. Activity Detector was measured by home-made instrument using electrical reading to test the physical flaw of the tape. Using a scale oE 0 to 10, lower the number, the better.
. ~ .
. 13. Activity Detector was measured by home-made instrument using electrical reading to test the physical flaw of the tape. Using a scale oE 0 to 10, lower the number, the better.
. ~ .
Claims (9)
1. A magnetic medium comprising a nonmagnet-ic susbstrate coated with a radiation-cured polymeric binder having magnetic particles dispersed therein characterized in that the binder comprises a radiation-cured mixture of a high molecular weight thermoplastic polymer and a radiation-curable acrylate prepolymer.
2. The magnetic medium of Claim 1 further characterized in that the radiation is electron beam radiation, the high molecular weight polymer is a linear polyurethane having a molecular weight of at least 50,000 and the radiation-curable acrylate pre-polymer is a di- or trifunctional acrylate prepolymer having a molecular weight of less than 10,000.
3. The magnetic medium of Claim 2 further characterized in that the radiation-curable acrylate prepolymer is difunctional or trifunctional and is an acrylated epoxy, acrylated urethane, acrylated alkyd urethane, acrylated polycaprolactam, acrylated polyether, acrylated polyester, or acrylated unsaturated acid modified drying oil.
4. The magnetic medium of Claim 1, 2 or 3 further characterized in that the ratio of high molecu-lar weight thermoplastic polymer to acrylate prepolymer is from 50:50 to 90:10 on a polymer solids basis by weight.
A process for making a magnetic medium comprising preparing a fluid mixture of a solution of a radiation-curable polymeric binder and magnetic par-ticles, coating a nonmagnetic substrate with the fluid mixture, evaporating the solvent from the coating to solidify the coating, calendering the dried coated substrate, and exposing the dried coated substrate to sufficient radiation to cure the coating characterized in that the polymeric binder comprises a mixture of a high molecular weight thermoplastic polymer and a radiation curable acrylate prepolymer.
6. The process of Claim 5 further character-ized in that the radiation is electron beam radiation.
7. The process of Claim 5 further character-ized in that the radiation is electron beam radiation, the high molecular weight polymer is a linear polyure-thane having a molecular weight of at least 50,000 and the radiation-curable acrylate prepolymer is a di- or trifunctional acrylate prepolymer having a molecular weight of less than 10,000.
8. The process of Claim 7 further charac-terized in that the radiation-curable acrylate prepoly-mer is an acrylated epoxy, acrylated urethane, acryla-ted alkyd urethane, acrylated polycaprolactam, acryla-ted polyether, acrylated polyester, or acrylated unsat-urated acid modified drying oil.
9. The process of Claim 7 further character ized in that the ratio of high molecular weight thermo-plastic polymer to acrylate prepolymer is from 50:50 to 90:10 on a polymer solids basis by weight.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US18997980A | 1980-09-22 | 1980-09-22 | |
| US189,979 | 1980-09-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1167408A true CA1167408A (en) | 1984-05-15 |
Family
ID=22699560
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000385988A Expired CA1167408A (en) | 1980-09-22 | 1981-09-16 | Electron beam curing of magnetic media |
Country Status (11)
| Country | Link |
|---|---|
| EP (1) | EP0060300A1 (en) |
| JP (1) | JPS5786131A (en) |
| AU (1) | AU546317B2 (en) |
| BR (1) | BR8106017A (en) |
| CA (1) | CA1167408A (en) |
| DE (1) | DE3137691C2 (en) |
| FR (1) | FR2491246A1 (en) |
| GB (1) | GB2084589B (en) |
| IE (1) | IE51908B1 (en) |
| MX (1) | MX158193A (en) |
| WO (1) | WO1982001099A1 (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4408020A (en) * | 1982-06-28 | 1983-10-04 | The B. F. Goodrich Company | Curable polyurethanes |
| JPS5979431A (en) * | 1982-10-29 | 1984-05-08 | Konishiroku Photo Ind Co Ltd | Magnetic recording medium |
| EP0123081A3 (en) * | 1983-03-09 | 1986-11-26 | DeSOTO, INC. | Coatings for magnetic recording structures and production thereof |
| US4507458A (en) * | 1983-04-14 | 1985-03-26 | Takeda Chemical Industries, Ltd. | Urethane acrylate compositions |
| JPS6057531A (en) * | 1983-09-07 | 1985-04-03 | Kao Corp | Magnetic recording medium |
| DE3332564A1 (en) * | 1983-09-09 | 1985-03-28 | Basf Ag, 6700 Ludwigshafen | MAGNETIC RECORDING CARRIERS |
| DE3418482A1 (en) * | 1984-05-18 | 1985-11-21 | Basf Ag, 6700 Ludwigshafen | MAGNETIC RECORDING CARRIERS |
| US4594262A (en) * | 1984-07-05 | 1986-06-10 | Minnesota Mining And Manufacturing Company | Electron beam adhesion-promoting treatment of polyester film base |
| US4543268A (en) * | 1984-07-05 | 1985-09-24 | Minnesota Mining And Manufacturing Company | Electron-beam adhesion-promoting treatment of polyester film base for magnetic recording media |
| JPH0610856B2 (en) * | 1984-08-04 | 1994-02-09 | ティーディーケイ株式会社 | Magnetic recording medium |
| US5028683A (en) * | 1988-04-22 | 1991-07-02 | Minnesota Mining And Manufacturing Company | Electron-beam curable polyurethane compositions; and method |
| US5281482A (en) * | 1988-04-22 | 1994-01-25 | Minnesota Mining And Manufacturing Company | Magnetic recording medium comprising magnetic particles and an electron beam curable polyurethane binder having segments derived from a specified unsaturated diol |
Family Cites Families (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB829512A (en) * | 1957-01-31 | 1960-03-02 | Dow Chemical Co | Method for cross-linking vinyl chloride polymers |
| US3104983A (en) * | 1959-08-26 | 1963-09-24 | Ibm | Method of curing magnetic tape binder comprising butadiene-acrylonitrile and phenolicresin with subatomic radiation |
| DE1240934B (en) * | 1965-09-15 | 1967-05-24 | Basf Ag | Binder for ferromagnetic powder in the manufacture of magnetogram carriers |
| DE2100037C3 (en) * | 1971-01-02 | 1980-06-19 | Hartmann, Job-Werner, Dr., 6700 Ludwigshafen | Process for the production of magnetic recording media |
| GB1431854A (en) * | 1972-04-07 | 1976-04-14 | Sony Corp | Magnetic recording media and methods of making them |
| US4072592A (en) * | 1974-05-20 | 1978-02-07 | Mobil Oil Corporation | Radiation curable coating |
| JPS5845474B2 (en) * | 1974-05-20 | 1983-10-11 | モビル オイル コ−ポレ−シヨン | radiation curable paint |
| JPS5921909B2 (en) * | 1974-10-31 | 1984-05-23 | 東レ株式会社 | Radiation curable coating composition |
| US4152485A (en) * | 1977-08-05 | 1979-05-01 | Toyo Boseki Kabushiki Kaisha | Magnetic recording medium |
| SE444991B (en) * | 1978-05-01 | 1986-05-20 | Minnesota Mining & Mfg | PHOTOPOLYMERIZABLE COMPOSITION AND SUBSTRATE COATED WITH THE COMPOSITION |
| FR2456963A1 (en) * | 1979-05-18 | 1980-12-12 | Eastman Kodak Co | PHOTOGRAPHIC PRODUCT HAVING A MAGNETIC RECORDING TRACK AND METHOD FOR THE PRODUCTION THEREOF |
| US4273633A (en) * | 1979-06-11 | 1981-06-16 | Union Carbide Corporation | Radiation curable dispersions containing high molecular weight essentially nonpolymerizable vinyl resins |
| FR2463478B1 (en) * | 1979-08-06 | 1986-07-18 | Sony Corp | MAGNETIC RECORDING ELEMENT |
| JPS5625230A (en) * | 1979-08-06 | 1981-03-11 | Sony Corp | Magnetic recording medium |
| GB2055877B (en) * | 1979-08-06 | 1983-07-20 | Sony Corp | Magnetic recording media |
-
1981
- 1981-09-16 CA CA000385988A patent/CA1167408A/en not_active Expired
- 1981-09-17 GB GB8128186A patent/GB2084589B/en not_active Expired
- 1981-09-18 IE IE218781A patent/IE51908B1/en unknown
- 1981-09-21 FR FR8117755A patent/FR2491246A1/en active Granted
- 1981-09-21 BR BR8106017A patent/BR8106017A/en unknown
- 1981-09-21 JP JP14929181A patent/JPS5786131A/en active Pending
- 1981-09-22 WO PCT/US1981/001276 patent/WO1982001099A1/en unknown
- 1981-09-22 MX MX18925381A patent/MX158193A/en unknown
- 1981-09-22 DE DE19813137691 patent/DE3137691C2/en not_active Expired
- 1981-09-22 EP EP19810902865 patent/EP0060300A1/en not_active Withdrawn
- 1981-09-22 AU AU75546/81A patent/AU546317B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| FR2491246A1 (en) | 1982-04-02 |
| IE51908B1 (en) | 1987-04-29 |
| AU546317B2 (en) | 1985-08-29 |
| GB2084589A (en) | 1982-04-15 |
| IE812187L (en) | 1982-03-22 |
| JPS5786131A (en) | 1982-05-29 |
| EP0060300A1 (en) | 1982-09-22 |
| BR8106017A (en) | 1982-06-08 |
| MX158193A (en) | 1989-01-16 |
| GB2084589B (en) | 1984-08-22 |
| AU7554681A (en) | 1982-04-01 |
| WO1982001099A1 (en) | 1982-04-01 |
| DE3137691C2 (en) | 1984-05-17 |
| FR2491246B1 (en) | 1984-12-28 |
| DE3137691A1 (en) | 1982-05-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4448846A (en) | Radiation-cured magnetic media and process for making same | |
| US4415630A (en) | Process of making magnetic recording medium | |
| US4526837A (en) | Magnetic recording medium | |
| US4568612A (en) | Magnetic recording media | |
| CA1167408A (en) | Electron beam curing of magnetic media | |
| US4058646A (en) | Magnetic recording media containing elastomeric polyurethane binders in the magnetic coating | |
| US4503198A (en) | Electron radiation curable resin | |
| EP0047321B1 (en) | Magnetic recording medium | |
| US4560617A (en) | Magnetic recording medium | |
| JPH0612564B2 (en) | Magnetic recording medium | |
| US4591528A (en) | Magnetic recording medium | |
| US4618535A (en) | Magnetic recording medium | |
| US4639389A (en) | Magnetic recording medium | |
| JPS6182327A (en) | Magnetic recording carrier | |
| US4959263A (en) | Magnetic recording medium | |
| US4152484A (en) | Magnetic recording media | |
| US4601947A (en) | Magnetic recording medium | |
| US4559265A (en) | Magnetic recording medium | |
| US4632878A (en) | Magnetic recording medium | |
| JP2008192239A (en) | Magnetic recording medium | |
| JPH0546016B2 (en) | ||
| JPH0576089B2 (en) | ||
| US4603081A (en) | Magnetic recording medium | |
| GB2130121A (en) | Magnetic recording medium and method for producing the same | |
| GB2081277A (en) | Magnetic Recording Layers |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |