CA1093905A - Process of producing a magnetic recording element - Google Patents
Process of producing a magnetic recording elementInfo
- Publication number
- CA1093905A CA1093905A CA262,503A CA262503A CA1093905A CA 1093905 A CA1093905 A CA 1093905A CA 262503 A CA262503 A CA 262503A CA 1093905 A CA1093905 A CA 1093905A
- Authority
- CA
- Canada
- Prior art keywords
- coating
- magnetic
- layer
- subbing
- parts
- 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
-
- 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
- G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
-
- 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
- G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
- G11B5/739—Magnetic recording media substrates
- G11B5/73923—Organic polymer substrates
- G11B5/73927—Polyester substrates, e.g. polyethylene terephthalate
Landscapes
- Paints Or Removers (AREA)
- Magnetic Record Carriers (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A process of producing a magnetic recording element comprising a non-magnetic support having provided thereon a sub-bing layer and further having provided thereon a magnetic layer comprising a ferromagnetic powder and a binder, in which the non-magnetic support is a biaxially stretched polyester and the subbing layer is formed by coating a coating solution of about 0.8 to about 5 wt% concentration of a solid component comprising an amorphous linear saturated polyester resin containing an aromatic dicarboxylic acid, 10 to 50 wt% of a vinylidene chloride addition polymerizable nitrile copolymer based on the polyester resin and an organic solvent mainly composed of methyl ethyl ketone, which comprises coating the subbing solution at a tempera-ture of about 100°C or below to provide a dry thickness of about 0.03 to about 2.0 µm, drying the coated layer and then coating the magnetic recording layer thereon.
A process of producing a magnetic recording element comprising a non-magnetic support having provided thereon a sub-bing layer and further having provided thereon a magnetic layer comprising a ferromagnetic powder and a binder, in which the non-magnetic support is a biaxially stretched polyester and the subbing layer is formed by coating a coating solution of about 0.8 to about 5 wt% concentration of a solid component comprising an amorphous linear saturated polyester resin containing an aromatic dicarboxylic acid, 10 to 50 wt% of a vinylidene chloride addition polymerizable nitrile copolymer based on the polyester resin and an organic solvent mainly composed of methyl ethyl ketone, which comprises coating the subbing solution at a tempera-ture of about 100°C or below to provide a dry thickness of about 0.03 to about 2.0 µm, drying the coated layer and then coating the magnetic recording layer thereon.
Description
``` 1~9390S
-BACKGROUND OF THE INVENTION
FieLd of the Invention The present invention relates to a process of pro-ducing a magnetic recording element such as a video tape, an audio tape, a tape for an electronic computer, a magnetic sheet, an instrumentation tape, etc., and, in particular, to a process of producing a magnetic recording element having provided thereon a subbing layer which provides excellent adhesion of the magnetic layer to the support and which does not cause blocking at the edges of a wide roll during production.
Description of the Prior Art Most supports of recently developed magnetic recording elements comprise polyethylene terephthalate. Polyethylene terephthalate has strong resistance to organic solvents and excellent mechanical strength because of biaxial stretching and crystallization to a high degree. However, it is required in magnetic recording elements obtained by coating a dispersion of ferromagnetic particles in a binder onto such a support that the support strongly adhere to the magnetic layer. For this purpose, various devices have been made.
With respect to subbing methods, there are known methods as are described in Japanese Patent Publications 22071/72 and 10243/74, Japanese Patent Applications (OPI) 46406/74, 46407~74, 32905/75, 32906/75 and 32907/75, etc. However, while these methods are goodat some points they are not good at other points and do not provide satisfactory subbing agents.
SUMMARY OF THE INVENTION
It is, therefore, one object of the present invention to provide a novel process of producing magnetic recording elements which provide effective adherence to polyesters, -- 1 -- .1,, / '~
~.~
1 particularly to polyethylene terephthalate.
That is, the present invention lS directed to a process of producing a magnetic recording element comprising a non-magnetic support having provided thereon a subbing layer having further provided thereon a magnetic layer comprising a ferromagnetic powder and a binder, in which the non-magnetic support is a biaxially stretched polyester and the subbing layer is formed by coating at a temperature below about 100C, to a dry thickness . of about 0.03 to about 2.0 ,um a subbing solution of a concentra-tion of about 0.8 to about 5 wt~ as solid components obtained by dissolving an amorphous linear saturated polyester resin con-taining an aromatic dicarboxylic acid and 10 to 50 wt% of a vinylidene chloride addition polymerizable nitrile copolymer in an organic solvent mainly composed of methyl ethyl ketone, drying the coated layer and then coating thereon the magnetic recording layer.
DETAILED DESCRIPTION OF THE INVENTION
As the amorphous linear saturated polyester used in the present invention, there are polyesters which have an average molecular weight of from about 10,000 to about 30,000, .
a solubility parameter of from 8.9 to 11.1, a tensile breaking strength of from about 20 to about 1000 kg/cm2, a softening point of from about 100 to about 200C, and a melting point of .
from about 12Q to about 250C.
Such polyesters are amorphous linear saturated poly-esters comprising as main components an aromatic dicarboxylic acid and a glycol. Preferred aromatic dicarboxylic acids are those having 8 to 18 carbon atoms, as exemplified by terephthalic acid, isophthalic acid, p-~-oxyethoxybenzoic acid, diphenyl-sulfonecarboxylic acid, diphenoxyethane dicarboxylic acid, ~)93905 S~sodium sulfoisophthalic acid, diphenylene dicarboxylic acid,
-BACKGROUND OF THE INVENTION
FieLd of the Invention The present invention relates to a process of pro-ducing a magnetic recording element such as a video tape, an audio tape, a tape for an electronic computer, a magnetic sheet, an instrumentation tape, etc., and, in particular, to a process of producing a magnetic recording element having provided thereon a subbing layer which provides excellent adhesion of the magnetic layer to the support and which does not cause blocking at the edges of a wide roll during production.
Description of the Prior Art Most supports of recently developed magnetic recording elements comprise polyethylene terephthalate. Polyethylene terephthalate has strong resistance to organic solvents and excellent mechanical strength because of biaxial stretching and crystallization to a high degree. However, it is required in magnetic recording elements obtained by coating a dispersion of ferromagnetic particles in a binder onto such a support that the support strongly adhere to the magnetic layer. For this purpose, various devices have been made.
With respect to subbing methods, there are known methods as are described in Japanese Patent Publications 22071/72 and 10243/74, Japanese Patent Applications (OPI) 46406/74, 46407~74, 32905/75, 32906/75 and 32907/75, etc. However, while these methods are goodat some points they are not good at other points and do not provide satisfactory subbing agents.
SUMMARY OF THE INVENTION
It is, therefore, one object of the present invention to provide a novel process of producing magnetic recording elements which provide effective adherence to polyesters, -- 1 -- .1,, / '~
~.~
1 particularly to polyethylene terephthalate.
That is, the present invention lS directed to a process of producing a magnetic recording element comprising a non-magnetic support having provided thereon a subbing layer having further provided thereon a magnetic layer comprising a ferromagnetic powder and a binder, in which the non-magnetic support is a biaxially stretched polyester and the subbing layer is formed by coating at a temperature below about 100C, to a dry thickness . of about 0.03 to about 2.0 ,um a subbing solution of a concentra-tion of about 0.8 to about 5 wt~ as solid components obtained by dissolving an amorphous linear saturated polyester resin con-taining an aromatic dicarboxylic acid and 10 to 50 wt% of a vinylidene chloride addition polymerizable nitrile copolymer in an organic solvent mainly composed of methyl ethyl ketone, drying the coated layer and then coating thereon the magnetic recording layer.
DETAILED DESCRIPTION OF THE INVENTION
As the amorphous linear saturated polyester used in the present invention, there are polyesters which have an average molecular weight of from about 10,000 to about 30,000, .
a solubility parameter of from 8.9 to 11.1, a tensile breaking strength of from about 20 to about 1000 kg/cm2, a softening point of from about 100 to about 200C, and a melting point of .
from about 12Q to about 250C.
Such polyesters are amorphous linear saturated poly-esters comprising as main components an aromatic dicarboxylic acid and a glycol. Preferred aromatic dicarboxylic acids are those having 8 to 18 carbon atoms, as exemplified by terephthalic acid, isophthalic acid, p-~-oxyethoxybenzoic acid, diphenyl-sulfonecarboxylic acid, diphenoxyethane dicarboxylic acid, ~)93905 S~sodium sulfoisophthalic acid, diphenylene dicarboxylic acid,
2,6-naphathalene dicarboxylic acid, etc. Preferred glycols are those having 2 to 10 carbon atoms, as exemplified by ethylene glycol, propylene glycol, butanediol, neopentylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-bisoxybenzene, bisphenol A, diethylene glycol, polyethylene glycol, etc. A
suitable molar ratio of the aromatic dicarboxylic acid to the glycol can range from 2:1 to 3:1. The other additives can be ~ present in an amount of about 5 mole % or less to the above two components and can be selected from aliphatic saturated dicarboxylic acids, aliphatic unsaturated dicarboxylic acids and oxydicarboxylic acids, preferably dicarboxylic acids having 13 or less carbon atoms. For example, suitable materials include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid,maleic acid, fumaric acid, 3-hydroxy-1,5-pentane dicarboxylic acid, 3-hydroxy-- propoxy dicarboxylic acid, hydroxy butylidene malonic acid, etc.
Methods of synthesizing these polyesters are described in British Patent 578,079, P.J.Flory, Journal of the American Chemical Society, 61, 3334 (1939) and 62, 2261 (19~0), R.W.Doak and H.N. Campbell, Journal of the Polymer Science, 18, 215 (1955), etc.
The term "vinylidene chloride addition polymerizable nitrile copolymer" as used in the present specification and claims means a copolymer of vinylidene chloride and acrylonitrile or methacrylonitrile. It is preferred that the softening content thereof range from about 120 to 150C and the nitrogen content thereof range from about 1 to 6%.
The copolymerization ratio of the addition polymeri-zable nitrile can be determined by the aforementioned nitrogen .
~093905 1 content and the molecular weight of the copolymer can be predictedby theaforementioned softening point in some extent. A preferred molecular weight ranges from about 8,000 to 40,000.
Methods of synthesizing these copolymers are described in ~apanese Patent Publication 9495/75 and 7791/57, U.S.Patents 2,906,721; 2,956,047; 3,002,956; 3,009,207; 3,018,197; 3,039,986;
suitable molar ratio of the aromatic dicarboxylic acid to the glycol can range from 2:1 to 3:1. The other additives can be ~ present in an amount of about 5 mole % or less to the above two components and can be selected from aliphatic saturated dicarboxylic acids, aliphatic unsaturated dicarboxylic acids and oxydicarboxylic acids, preferably dicarboxylic acids having 13 or less carbon atoms. For example, suitable materials include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid,maleic acid, fumaric acid, 3-hydroxy-1,5-pentane dicarboxylic acid, 3-hydroxy-- propoxy dicarboxylic acid, hydroxy butylidene malonic acid, etc.
Methods of synthesizing these polyesters are described in British Patent 578,079, P.J.Flory, Journal of the American Chemical Society, 61, 3334 (1939) and 62, 2261 (19~0), R.W.Doak and H.N. Campbell, Journal of the Polymer Science, 18, 215 (1955), etc.
The term "vinylidene chloride addition polymerizable nitrile copolymer" as used in the present specification and claims means a copolymer of vinylidene chloride and acrylonitrile or methacrylonitrile. It is preferred that the softening content thereof range from about 120 to 150C and the nitrogen content thereof range from about 1 to 6%.
The copolymerization ratio of the addition polymeri-zable nitrile can be determined by the aforementioned nitrogen .
~093905 1 content and the molecular weight of the copolymer can be predictedby theaforementioned softening point in some extent. A preferred molecular weight ranges from about 8,000 to 40,000.
Methods of synthesizing these copolymers are described in ~apanese Patent Publication 9495/75 and 7791/57, U.S.Patents 2,906,721; 2,956,047; 3,002,956; 3,009,207; 3,018,197; 3,039,986;
3,053,806; 3,053,870; 3,058,846 and 3,058,949; British Patents 928,114 and 952,075, German Patents 1,102,400 and 1,116,901, etc.
The composition of the subbing layer in accordance with the present invention is preferably such that the vinylidene chloride-addition polymerizable nitrile copolymer is present in an amount of about 3 to about 60 wt%, preerably 10 to 50 wt %, based on the amorphous linear polyester resin.
The subbing layer of the present invention is coated onto a non-magnetic support using an organic solvent, followed by drying. The dry thickness of the subbing layer is preferably about 0.03 to about 2.0 ym, more preferably 0.2 to 1.5 ym.
The adhesive strength required in the present invention is such that the adhesive strength can be effectively maintained in the atmosphere at temperatures of from -20 to 70C and at a humidity of 80% RH, which means a tensile strength of greater than about 100 g/cm2 at 30C and greater than about g/cm2 at -20C to 0C, at a velocity of 20 cm/min. or less, preferably 10 to 20 cm/min., using a TOM tensile testing machine.
In addition, it is preferred that chlori~e type organic solvents not be used in the present invention, that the drying rate be rapid without using water in the present invention since water evaporates more slowly, and that no harmful substance be released upon heating or the like in the present invention.
1 Further, the subbing layer in accordance with the present invention may, if desired, contain additives to a magne~ic layer as will be later described, such as a dispersing agent, a lubricating agent, an abrasive, an antistatic agent,etc.
It is preferred that the total of these additives be added in an amount of less than 10 wt% based on the subbing layer.
Suitable examples of organic solvents which can be used upon coating include methyl ethyl ketone which is a main component and, in addition, other compatible ketone type solvents such as acetone, methyl isobutyl ketone, cyclohexanone, etc.:
ester type solvents such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, glycol monoethyl ether acetate, etc.;
glycol ether type solvents such ether, glycol dimethyl ether, glycol monoethyl ether, dioxane, etc.; tar type (aromatic hydro-carbon) solvents such as benzene, toluene, xylene, etc.
It is preferred that the aforementioned organic solvent ke used with the mixing ratio of methyl ethyl ketone being about 50 to about 100 wt%, more preferably 80 to 95 wt%. About 10 to about 50 parts by weight of the copolymer based on 100 parts by weight of the polyester resin are mixed, and dissolved in organic solvent at a concentration of the above two components of about 0.8 to about 5% by weight, as a coating solution for subbing layer.
As methods of coating the subbing layer of the present invention onto a non-magnetic support, there are utilized air doctor coating, blade coating, air knife coating, squizz coating, immersion coating, reverse roll coating, transfer roll coating, gravure coating , kiss coating, cast coating, spray coating, etc.
It is also possible to use other methods, the details of which are described in Coating Kogaku (Coating Technology), pages 253 - 277, 1 March 20, 1971, published by Asakura Shoten, Japan.
Drying conditions after coating the subbing layer are performed at temperatures of less than about 100C, preferably 70 to 100C, more prefera~ly 80 to 90C, using an ir flow of 2 ,Sec 2 ~ec about 1 to about 5 kl/m ~ preferably 2 to 3 kl/m~, and in a period of time of about 2 to about 10 seconds.
As this non-magnetic support, polyesters such as polyethylene terrephthalate, polyethylene-2,6-naphthalate and polybutylene terephthalate are employed as materials thereof.
A polyester film subjected to biaxial stretching is preferred, with the stretching degree in the length direction being about 3 to about 6 times and with the stretching degree in the width direction being about 1.2 to about 4 times. A preferred ratio of the stretching in the length to stretching in the width direction is a stretching ratio more than 1Ø
A thickness o~ these non-magnetic supports is about 3 to about 100 ~m in the case of a film, a tape or a sheet, more preferably 5 to 50 ym, and in case of disk or card a thickness of about 0.5 to 10 mm is best used. In the case of a drum, the shape is rendered cylinder like and determined depending upon the recorder to be used.
The subbing layer in accordance with the present invention is particularly effective when the non-magnetic support is in the shape of a film, a tape or a sheet.
The aforementioned non-magnetic support may have a back coating on the surface opposite to the magnetic layer, for the purpose of static prevention, print-through prevention, or the like.
The useful back coating procedures are described in, for example, U.S.Patents 2,804,401; 3,293,066; 3,617,378;
` 1~93905 t 3,062,676; 3,734,772; 3,476,596; 2,643,048; 2,803,556; 2,887,462;
2,923;642; 2,997,451; 3,007,892; 3,041,196; 3,115,420; 3,166,685 and 3,761,311; etc.
Processes of producing a magnetic material used in forming a magnetic recording layer of the present invention are described in Japanese Patent Publications 15/60; 26794/64;
186/68; 28043/72; 28045/72; 28046/72; 28048/72; 31445/72; 11162/73;
21331/73 and 33583/73; Soviet Patent 308,033, etc. in detail.
~ The magnetic materials described in the above patents mainly comprise ferromagnetic powders, a binder and a coatin~ solvent, and may additionally optionally contain additives such as a dispersing agent, a lubricating agent, an abrasive, an antistatic agent, etc.
Examples of ferromagnetic powders which can be used in accordance with the present invention include known ferro-magnetic powders suchas ~-Fe2O3, Fe3O4, Co-containing Fe3O4, Bertholi~e compounds of ~-Fe2O3 and Fe3O4 (of the formula FeOx, 1.33 <x <1.50), Bertholide compounds of Co-containing ~-Fe2O3 and Fe3O4 (of the formula FeOx, 1.33 ~x <1.50, CrO2, Co-Ni alloys, Co-Ni-P alloys, Co-Ni-B alloys, Co-Ni-Fe alloys, Co-Ni-Fe-P alloys, Co-Ni-Fe-B alloys, Co-Ni-Zn alloys, Co-Ni-Cr-P alloys, Co-Ni-Cr-B alloys, Fe-Mn-Zn alloys, Fe-Co-Ni-Cr alloys,etc., as are specifically described in Japanese Patent Publications 5009/64, 10307/64, 14090/69, 18372/70, 22513/72, 22062/72, 28466/71, 38755/71, 4286/72, 12422/72, 17284/72, 18509/72, 18573/72, 39120/73 and 39639/73, U.S.Patents 3,026,215; 3,031,341; 3,100,194; 3,242,055 and 3,389,014;
British Patents 752,659; 782,762 and 1,007,323, French Patent 1,107,654; German Patent Application (OLS) 1,281,334, etc.
These ferromag~etic powders have a particle size , 105~3~0S
1 f about 0.2 to about 2 microns (length) preferably less than 1.5 micron and a length/width ratio of about 1/1 to about 20/1, preferably more than 5/1.
Examples of binders which can be used in the present invention include a thermoplastic resin, a thermosetting resin or a reactive resin (all of which are known and are conventional) or a mixture thereof.
Preferred thermoplastic resins include those having a softening point of about 150C or less and an average molecular weight of from about 10,000 to about 200,000, and a polymerization degree of about 2~0 to about 2000, examples of w~ich include, a vinyl chloride-vinyl acetate copolymer, a vinyl chloride-vinyli-dene copolymer, a vinyl chloride-acrylonitrile copolymer, an acrylic acid ester-acrylonitrile copolymer, an acrylic acid ester-vinylidene chloride copolymer, an acrylic acid ester-styrene copolymerr a methacrylic acid ester-acrylonitrile copolymer, a methacrylic acid ester-vinylidene chloride copolymer, a methacrylic acid ester-styrene copolymer, a urethane elastomer, polyvinyl fluoride, a vinylidene chloride-acrylonitrile copolymer, a butadiene-acrylonitrile copolymer, a polyamide resin, a poly-vinyl butyral, a cellulose derivative (e.g., cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, etc.), a styrene-butadiene copolymer, a polyester resin, a chlorovinyl ether-acrylate copolymer, various synthetic rubber type thermoplastic resins mixtures thereof, etc.
Examples of these resins are styrene-butadiene rubber, acrylonitrile-butadiene rubber, chloroprene, rubber, etc. and they are described in ~apanese Patent Publications 6877/62;
12528/64; 19282/64; 5349/65; 20907/65; 9463/66; 14059/66;
16985/66; 6428/67; 11621/67; 4623/68; 15206/68; 2889/69;
` 1093905 1 17947/69; 18232/69; 14020/70; 14500/70; 18573/72; 22063/72;
22064/72; 22068/72; 22069/72; 22070/72; 27886/73 and 3121/74;
U.S.Patents 3,144,352; 3,419,420; 3,499,789 and 3,71~,887, etc.
Preferred thermosetting resins or reactive resins have a molecular weight of less than about 200,000 in the state of a coating solution, but the molecular weight thereof becomes essentially infinite due to reactions such as condensation, addition, etc., after coating and drying.
Further, of these resins, resins which do not soften or melt until they are heat decomposed are preferred. Specific examples of these resins are, for example, a phenol resin, an epoxy resin, a polyurethane setting resin, a urea resin, a melamine resin,an alkyd resin, a silicone resin, an acryl type reactive resin, an epoxy-polyamide resin, a mixture of a high molecular weight polyester resin and an isocyanate prepolymer, a mixture of a methacrylate copolymer and a diisocyanate prepolymer, a mixture of a polyester polyol and a polyisocyanate, a urea-formaldehyde resin, a mixture of a low molecular weight glycol/a high molecular wei~ht dLol/triphenylmethane triisocyanate, a polyamine resin, mixtures thereof, etc.
Details on these resins are given in Japanese Patent Publications 8103/64; 9779/65; 7192/66; 8016/66; 14275/66;
18179/ 67,12081/68; 28023/69; 14501/70; 24902/70; 13103/71;
22065/72; 22073/72; 28073/72; 28045/72; 28048/72 and 29822/72;
U.S.Patents 3,144,353; 3,320,090; 3,437,510; 3,597,273;
3,781,210 and 3,781,211, etc.
These binders can be used singly or in combination, and may contain additives. The binders are used ~ithin a range such that the mixing ratio of ferromagnetic powder(s) to the binder is about 10 to about 200 parts b~ weight, _ g _ , . . .
)93905 1 preferably 10 to 100 parts by weight, of the binder per 100 parts by weight of the ferromagnetic powder~s) as weight ratio.
To the magnetic recording layer, a dispersing agent, a smoothing agent, an abrasive, an antistatic agent, etc., can be added, in addition to the aforementioned binder and ferromagnetic powders.
Examples of dispersing agents are a fatty acid having 12 to 18 carbon atoms (RlCOOH wherein Rl is an alkyl or alkenyl group having 11 to 17 carbon atoms) such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, linolic acid, linoleic acid, strearolic acid, etc.; metallic soaps consisting of alkali metal (~i, Na, K, etc.) salts or alkaline earth metal (Mg, Ca, Ba) salts of the aforementioned fatty acids, fluorine- `
containing compounds of the aforementioned fatty acid esters (e.g., C8F17OOC4 - SO3Na); lecithin; trialkylpolyolefin oxy quaternary ammonium salts (~herein the alkyl group has 1 to 5 carbon atoms and the olefin is ethylene, propylene, etc.), etc.
In addition, a higher alcohol having 12 or more carbon atoms such as lauryl alcohol, tridecyl alcohol, myristyl alcohol, pentadecyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, linoleyl alcohol, and sulfonic acid esters of these higher alcohols, such as sodium stearyl alcohol sulfate (C18H32OSO3Na), etc., can also be used. These dispersing agents are employed by adding within a range of from about 0.5 to about 20 parts by weight per 100 parts of the binder. Details are given in Japanese Patent Publications 28369/64, 17945/69, 7441/73, 15001/73, 15002/73, 16363/73 and 4121/75, U.S.Patents 3,387,993 and 3,470,021, etc.
, 1 Examples o~ lubricants which can be used include a silicone oil such as a dialkyl polysiloxane (wherein the alkyl group has 1 to 5 carbon atoms), a dialkoxy polysiloxane (whe:rein the alkoxy group has 1 to 4 carbon atoms), a mono-alky:L monoalkoxy~polysiloxane (wherein the alkyl group has 1 to 5 carbon atoms and the alkoxy group has 1 to 4 carbon atoms), phenyl polysiloxane, a fluoroalkyl polysiloxane (wherein the alkyl group has 1 to 5 carbon atoms~, etc.; electro-conductive powders such as graphite, etc.; inorganic powders such as molybdenum disul~ide, tungsten disulfide, etc.; plastic powders such as polypropylene, a polyethylene-vinyl chloride copolymer, polytetrafluoroethylene, etc.; an a-olefin polymer; unsaturated alphatic hydrocarbons liquid at normal temperature (compounds -having an a-olefinic double bond attached to the carbon at the terminal thereof, about 15 to about 20 carbon atoms); a fatty acid ester comprising a monobasic fatty acid having 12 to 20 carbon atoms and a monovalent alcohol having 3 to 12 carbon atoms;
etc. These lubricants are added in an amount of about 0.2 to about 20 parts by weight per 100 parts by weight of binder. These lubricants are described in detail in Japanese Patent Publications 23889/68, 40461/71, 15621/72, 18482/72, 28043/72, 30207/72, 32001/72, 7442/73, 14247/74 and 5042/75, U.S.Patents 3,470,021;
3,492,235; 3,497,411; 3,523,086; 3,625,760; 3,630,772; 3,634,253;
3,542,539 and 3,687,725. IBM Technical Disclosure Bulletin, Vol. 9, No. 7 page 779 (December 1966), ELEKTRONIK,1961, No. 12, page 380, etc.
As abrasives there are used those which are generally employed in this art which include fused alumina, silicon carbide, chromium oxide, corundum, artificial corundum, diamond, artificial diamond, garnet, emery ~main components: corumdum and -~ 10'33905 1 magnetite), etc. The abrasives have an average particle size of about 0.05 to about 5 ,u, preferably 0.1 to 2 ~. These abrasives are added in an amount of about 0.5 to about 20 parts by weight per :lO0 parts by weight of the binder. Details thereon are given in Japanese Patent Publications 18572/72, 15003/73 and 15004/73 (U.S.Patent 3,617,378), 39402/74 and 9402/75, U.S.Patents 3,007,807; 3,041,196; 3,293,066; 3,630,910 and 3,687,725, British Patent 1,145,349, German Patent 853,211 and 1,101,000, etc.
Examples of antistatic agents which can be used include electroconductive powders such as carbon black, carbon black graft polymers, e.g., a reaction product of a copolymer of carbon black and an acrylate, methacrylate, vinyl chloride or styrene polymer which is prepared by graft polymerization, etc.;
natural surface active agents such as saponin, etc.; nonionic surface active agents such as alkylene oxide type, glycerine type, glycidol type, etc. surface active agents; cationic surface active agents such as higher alkylamines, quarternary ammonium salts, pyridine or other heterocyclic ring compounds, phosphonium or sulfonium, etc. surface active agents; anionic surface active agents containing an acid group such as a carboxylic acid, sulfonic acid, phosphoric acid, sulfuric acid ester, phosphoric acid ester group etc. surface active agents; amphoteric surface active agents such as amino acid, amino-sulfonic acid, sulfuric acid or phosphoric acid esters of amino alcohols, etc. A
suitable amount of the elctroconductive powder is at least about 10 % by weight, preferably 0.1 to 8 % by weight, and of the surface active agent is at least about 10 % by weight, preferably 0.1 to 7 % by weight, each based on the weight of ferromagnetic powder.
Some surface ac~ive agents which can also be used as 1 antistatic agents are described in Japanese Patent Publications 22726/71, 24881/72, 26882/72, 15440/73 and 26761/73, U.S.Patents 2,271,623; 2,240,472; 2,288,226; 2,676,122; 2,676,924; 2,676,975;
2,69L,566; 2,727,860; 2,730,498; 2,742,279; 2,739,891; 3,068,1~1i 3,15~,484; 3,201,253; 3,210,191; 3,294,540; 3,415;649; 3,441,413;
3,442,654; 3,475,174 and 3,5~5,974, German Patent Application (OLS) 1,942,665, British Patents 1,077,317 and 1,198,450, Oda Ryohei, Kaimen Kasseizai no Gosei to sono Oyo (Synthesis of Surface Active Agents and Their Application), 1964, published by Maki Shoten, A.M. Schwartz & J.W. Perry, Surface Active Agents, 1958, published by Interscience Publication Incorporated, J.P. Sisley, Encyclopedia of Surface Active Agents, Vol. 2, 1964, published by Chemical Publish Company, Kaimen Kasseizai Binran (Handbook of Surface Active Agents), sixth ed., December 20, 1966, published by Sangyo Tosho Kabushiki Kaisha, etc.
These surface active agents may be added singly or in combination. They are used as antistatic agents, but they may also be utilized sometimes for other purposes, for example, for dispersion, improvement of magnetic characteristics, improvement of lubricity or as a coating aid.
The provision of the magnetic recording layer is performed by dissolving the aforementioned composition in an organic solvent and coating the resultant coating solution on the subbing layer of the present invention which is provided on a non-magnetic support.
For kneading (dispersion) of a magnetic coating solution, various kneading machines can be used. For example, there are a two roll mill, a three roll mill, a ball mill, a pebble mill, a trommel, a sand grinder, a Szegvari attritor, a high-speed impeller dispersing machine, a high speed stone mill, a high ,. . .
)9390S
1 speed impact mill, a disper, a kneader, a high speed mixer, a homogenizer, a ultrasonic dispersing machine, etc.
Technology regarding kneading (dispersion) is described in T.C.Patton, Paint Flow and Pigment Dispersion, 1964,published by John Wiley ~ Sons, and also described in U.S.Patent 2,581,41 and 2,855,156.
Coating of the aforementioned magnetic recording layer onto a subbing layer of the present invention is performed in a conventional manner by e.g., by any of the procedures earlier described for coating the subbing layer.
Examples of organic solvents which can be used for coating are ketone type solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.;
alcohol type solvents such as methanol, ethanol, propanol, butanol, etc.; ester type solvents such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, glycol acetate, monoethyl ether, etc.; glycol ether type solvents such as ether, glycol dimethyl ether, glycol monoethyl ether, dioxane, etc.; tar type (aromatic hydrocarbon) solvents such as benzene, toluene, xylene, etc., 2~ which can be used alone or in combination.
The thus formed magnetic layer is dried, i necessary, after subjecting the ferromagnetic powders in the layer provided on the subbing layer to an orientation. If necessary, a surface smoothing treatment can be performed or the material cut into a desired shape, a magnetic recording element thus being produced.
In particular, it has been found that if a surfacé smoothing treatment of the magnetic recording layer is performed, a magnetic recording element having a smooth surface and excellent abrasion resistance can be obtained.
In this case, the magnetic field for orientation is ~0939~5 I about 500 to 2000 Gauss (direct current or alternating current), drying is at about 50 to 100C, preferably 70 to 100C, more preferably 80 to 90C and during drying air is blo~n on the A element at an~ lr flow of about 1 to about 5 kl/m2~, preferably 2 to 3 kl/m2~, with the drying time being about 30 seconds to 10 minutes, preferably 1 to 5 mins.
The direction the orientation of the magnetic material is determined depending upon its use. That is, in the case ofa sound tape, a compact video tape, a memory tape, etc., the direction for orientation is parallel to the longitudinal direction of the tape; in the case of a video tape for broadcast-ing, orientation is performed at an angle of 30 to 90C to the longitudinal direction.
Methods for orientation of magnetic powders are also described in the following patents: U.S.Patents 1,949,840;
2,796,359; 3,001,891; 3,172,776; 3,416,949; 3,473,960 and 3,681,138 and Japanese Patent Publications 3427/57, 28368/64, 23624/65, 23625/65, 13181/66, 13043/73 and 39722/73, etc.
~ A surface smoothing treatment can be performed by calendering after drying using a smoothening sheet ~fter coating, etc., as is described in U.S.Patents 2,688,567; 2,- 30,32. and 3,783,023, German Patent Application (OLS) 2,405,222, Japanese Patent Applications (OPI) 53631/74 and 10337/75, etc. `--It has been ~onfirmed that the magnetic recording element obtained in accordance with the method of the present invention as explained above has strong adherance between the magnetic recording layer and the polyester support by the provision of the subbing layer, and, further, the present invention provides a method which does not cause blocking at the edges of a wide sheet or tackiness problems upon coating a wide sheet.
~)9390S
1 The present invention will now be described in more detail with reference to Examples and Comparative Examples hereinbelow. It can easily be understood that components, ratios, the order of operations or the like shown herein can be modified without departing fro~ the spirit and scope of the present invention.
Accordingly, the present invention is not to be limited to the examples hereinbelow.
All parts in the examples and comparative examples below are by weight.
Example 1 Onto a polyethylene terephthalate film (22 ,um thick) Subbing Solution I having the following formulation was uniformly coated in a 0.4 pm dry thickness.
Subbing Solution I (concentration : 2 wt% solution) Amorphous Linear Saturated Polyester (terepolymer of isophthalic acid, sebacic acid and ethylene glycol(l:l:4.2 molar ratio) average molecular weight: 17000, limiting viscosity (30C., 0.5% solution of phenol/
tetrachloroethane=6/4): 0.54 70 parts Copolymer of Vinylidene chloride and Acrylonitrile (nitrogen content: 5.1g, viscosity of - solution (25C., 2 wt% dimethyl formamide solution): 2.2 cp) 30 parts Solvent Mixture of Methyl Ethyl Xetone and Cyclohexane (9 : 1 volume)5000 parts The coating was dried at 80C. for 7 seconds in an air flow of 2.5 kl/m2/sec. to form a subbing layer.
Four specimens of the polyethylene terephthalate film having the subbing layer aforementioned were prepared. Onto the subbing layer of each of the specimens, the following four kinds of Magnetic Coating Solutions A, B, C and D were coated, respectively, in a dry thickness of 8 ~m. After orientation in a ~Q939(~5 1 direct current magnetic field of 1500 ~auss and then drying for 3 mins. at 90 to 95C in an air flow of 3 kl/m2/sec., the films were slit to a 1/~ inch width to obtain magnetic tapes, which were identified as Sample Nos. I-A, I-B, I~C and I-D, respectively.
Magnetic Coating Solution A
Magh~mite ( ~-Fe2O3, Hc = 295 Oe, particle size: 0.~3 x 0.03 x 0.5 ~m)100 parts Vinyl Chloride-Vinyl Acetate Copolymer (copolymerization ratio: 75/25~wt%), molecular weight: 450) 25 parts Polybutyl Acrylate (molecular weight:
lQ about 450) 5 parts Carbon Black (particle size: about 40 ~m) 7 parts Dimethyl Polysiloxane (Degree of polymerication;
about 60) 0.3 part Methyl Ethyl Ketone/Methyl Isobutyl Ketone (1/1 volume) solvent mixture300 parts Magnetic_Co_ting Solution B
Ferromagnetic Fe-Co-Ni Alloy Powders (Hc= 600 Oe, particle size: 0.03 x 0.03 x 0.3 ~m) 100 parts Polyurethane Resin (reaction product of polyethylene adipate and m-xylene diisocyanate, (1.2: 1 molar ratio) molecular weight: 130,000) 15 parts Alkyd Resin (reaction product of glycerine, terephthalic acid and a non-drying oil, (1.2: 2 : 0.5 molar ratio), hydroxyl value:l30, oil length: 29 %) 7 parts Polyisocyanate (a 75 wt% butyl acetate solution of the reaction product of 1 mol of trimethylol propane and 3 mols of 2,4-tolylene diisocyanatel tradename "Desmodur~-75", manufactured by Bayer A.G.) 7 parts Lecithin 1 part Trifluoroethylene chloride 0.5 parts Butyl Acetate 320 parts 10~3905 1 Magnet_c Coatlng Solution C
Co-containing Magetite (Hc = 550 Oe, particle size : O.04 x O.04 x O.6 ~m) 100 parts Vinyl Chloride-Vinyl Acetate Copolymer (copolymerization ratio: 75/25 (wt%), polymerization degree:450) 10 parts Butyl Acrylate-Acrylonitrile Copolymer (copolymerization ratio: 78/22 (wt~), polymerization degree:900) 26 parts Polyisocyanate (same as Magnetic Coating Solution B) 5 parts . Lecithin 1 part Oleic Acid 1.5 part Carbon Black (particle size: about 80 ~m) 7 parts Butyl Acetate/Toluene (1/1) Solvent Mixture 300 parts Magnetic Coating Solution D
Magemite ( ~-Fe2O3, Hc = 295 Oe, particle size: 0.03 x 0.03 x 0.5 lum) 100 parts Nitrocellulose (viscosity: RS 1/2, nitrogen content: 11.8 to 12.20, molecular weight: 30,000) 10 parts Polyether-type Polyurethane Prepolymer (the reaction product of 1,4-oxybutylene glycol and toluene diisocyanate (1.3: 1.6 molar ratio), which has an -NCO group at the terminals thereof molecular weight: 2,000) 20 parts Lecithin 1 part amyl Stearate 0.3 part Carbon Black (particle size: about 50 ~um) 5 parts Polyamine( 4,4'-methylenebis-2-chloroaniline) 2 parts Butyl Acetate/Methyl Ethyl Ketone (1/1 volume) Solvent Mixture280 parts .
lQ939~)~
1 Comparative Example 1 Subbing Solution Cl (concentration: 2 wt % solution) Amorphous Polyester Resin (terpolymer of terephthalic acid, ethylene glycol and triethylene glycol(l: 1.8 : 0.5 molar ratio), softening point: 65C) 97 parts Polycarbonate Resin (bisphenol A type*, molecular weight: 40,000) 3 parts Methyl Ethyl Ketone/Cyclohexane (9/1 volume) Solvent Mixture 5000 parts ~ IH3 IT ~
Subbing solution CI having the formulation described above was coated on a polyethylene terephthalate film (22 ym thick as in Example l, to a 0.4 ~m by thickness followed by drying as in Example 1. Magnetic Coating Solution A was further coated thereon to a dry thickness of 8 ~m, subjected to orientation treatment, and dried and slit in a 1/4 width all as in Example 1. Thus, a magnetic tape was obtained, which was identified as Sample No. ¢I-A.
With respect to Sample Nos. I-A, I-B, I-C, I-D and CI-A, a friction pull test(stripping-off at an angle of 180 ) was performed (JIS K6744-1963, ASTM D903-49(1965)), in which a cellophane adhesive tape (~IS Z1522) was uniformly adhered to the magnetic layer of each magnetic tape 1/4 inch wide and the friction pull strength at an angle of 180 (g/cm) was measured at various temperatures using a TOM tensile testing machine. The results are shown in Table 1 below.
-- 19 -- ' , 1 Table 1 Sample No. Friction Pull Strength at 180 (g/cm) _ I-.A 30 30 40 70 118 45 I~C 40 45 47 82 140 105 It can be seen from the results above that the samples obtained in accordance with Example 1 (Sample Nos. I-A, I-B, I-C
and I-D~ had a good 180 friction pull strength, that is, good adhesive property, whereas the sample obtained in accordance with Comparative Example 1 (Sample No. CI-A) showed a poor adhesive property as a whole, in particular, a poor adhesive property at low temperature.
EXAMP_E 2 A subbing layer having a dry thickness of 0.4 pm was formed as in Example 1 ex~cept that the ratios of the amorphous : linear polyester and the vinylidene-acrylonitrile copolymer of Subbing Solution I used Example 1 were modified as indicated in Table 2 below.
Table 2 Subbing Solution Nos. Polyester/Copolymer (concentration: 2 wt~) _ (wt%? _ _ II 100~0 ' IV 80/20 VI
Onto each of these subbing layers, Magnetic Coating .
i, , , , , .,. .~ . . . . ; ..
~093~5 1 Solution C was uniformly coated in a dry thickness of 10 ~m.
After orientation at a direct current magnetic field of 1500 Gauss and then dryina at 90C for 8 mins. at an air flow of 2.5 kl/m2/sec., the films were slit to a 1/4 inch width.
Magnetic tapes were thus obtained which were identified as Sample Nos. II-C, III-C, IV-C, V-C, VI-C and VII-C.
A friction pull strength at an angle of 180 of each of the samples was measured at 25C as in Example 1, the results of which are shown in Table`3 below.
Table 3 Sample Nos.Friction Pull Strength at 180 (25C) _ (~/cm3 It can ~e seen from the results above that Sample Nos.
II-C, VI-C and VII-C were considerably inferior to Sample Nos.
III-C, IV-C and V-C; good results were obtained when the ratio of the vinylidene chloride-acrylonitrile copolymer incorporated in the amorphous linear polyester resin was 10 to 50 wt %.
Example 3 Subbing Solution VIII !concentration: about 3 wt% solution) Amorphous ~inear Saturated Polyester ~terpolymer of terephthalic acid, ethylene glycol and tri-ethylene glycol(l: 2 : 0.4 molar ratio), average molecular weight:l9,000, softening point: 120C, solubility parameter: 9.1) 85 parts Vinylidene Chloride-Acrylonitrile Copolymer (nitrogen content: 1.5%, specific viscosity (25C, 1 wt% tetrahydrofuran solution): 1.5)15 parts Methylethyl Ketone/Tetrahydrofuran (8/2 volume) Solvent Mixture 3000 parts .,~
.
~093905 1 Subbing Solution VIII described above was uniformly coated onto a polyethylene terephthalate film (having a thickness of 36 ym) in a dry thickness of 1.5 ~um. After drying at 85C for 5 secs. at an air flow of 2.5 kl/m /sec., Magnetic Coating Solution A(see Example 1) was further coated thereon in a dry thickness of 8 ,um, and subjected to orientation at a direct current magnetic field of 1500 Gauss, followed by drying at 90 to 95C for 3 mins, at an air flow of 3 kl/m2/sec. The film thus obtained was slit into a 1/4 inch width. A magnetic tape was obtained which was identified as Sample VIII-A.
Comparative Example 2 Subbing Solution CII (concentration: about 3 wt% solution) Amorphous Linear Saturated Polyester (same as in Subbing Solution VIII)85 parts Vinyl Chloride-Vinyl Acetate Copolymer (copolymerization ratio: 87/13 (wt~), polymerization degree: 420)15 parts ~ethyl Ethyl Ketone/Tetrahydrofuran (8/2 volume) Solvent Mixture3000 parts A magnetic tape was prepared using Subbing Solution C II described above as in Example 3, which was identified as Sample C II-A.
Comparative Example 3 Subbing Solution C III(concentration: about 3 wt% solution) Amorphous Linear Polyester(same as in Example 3) 85 parts Epoxy Resin (the reaction product of epichloro-hydrin and diphenyl propane, epoxy equivalent: 470, molecular wei~ht: 1,000 "Epikote*1001", trade name, produced by Shell Chemical Co.,~td.)15 parts Methyl Ethyl Ketone/Tetrahydrofuran (8/2 volume) Solvent Mixture 3000 parts *Trade Mark 1t~93905 1 A magnetic tape was prepared using Subbing Solution C III described above as in Example 3, which was identified as Sample C III-A.
Comparative Example 4 Subbing Solution C IV(concentration: about 3 wt% solution) -, Amorphous Linear Polyester (same as in Example 3) 85 parts Straight Chain Polyurethane (terpolymer of adipic acid, 1,4-butanediol and diisocyanate (1: 1 : 0.2 molar ratio) molecular weight: 36,000) 15 parts Methyl Ethyl Ketone/Terahydrofuran (8/2 volume) Solvent Mixture 3000 parts A magnetic tape was prepared using Subbing Solution C IV as in Example 3 which was identified as Sample C IV-A.
With respect to Samples VIII-A, C II-A, C~III-A and C IV-A obtained in accordance with Example 3, and Comparative Examples 2, 3 and 4, the friction pull strength (g/cm) at an angle of 180 was measured at various temperature, the results of which are shown in Table 4 below. The measurement was performed as in Example 1.
Table 4 Sample Nos. Friction Pull Strength at 180 (g/cm) ; VIII-A 30 33 40 77 120 60 As can be seen from the results above, Sample VIII-A
had a stable adhesive strength as in Samples I-A, I-B, I-C
and I-D, without a remarkable decrease in adhesive property at a temperature range of from -20C to 70C. On the other hand, Samples C II-A, C III-A and C IV-A showed a poor adhesive .,. ~ .
- 1093~1~S
1 strength, of 40 to 60 g/cm, even at room temperature (30C), which was l/2 that of Sample VIII-A. In particular, the adhesive strength of Sample C III-A was abnormally low at low temperatures (-20C to 0C), i.e., 2 to lO g/cm; thus, good adhesive strength as observed in the subbing layers obtained in accordance with the present invention could not be obtained.
From these results it was confirmed that the composition of the subbing layer in accordance with the present invention, i.e., the two component mixture of an amorphous linear saturated polyester and a vinylidene chloride-an addition polymerizable nitrile copolymer, possesses extremely superior characteristics as compared to an amorphous linear saturated polyester and another resin.
Comparative Example 5 Subbing Solution C V (concentration: about 5.3 wt% solution) Vinylidene Chloride~Acrylonitrile Copolymer (same as in Example l)15 parts Polyester Resin ("Desmophen*2200", tradename, made by Bayer A.G.: the reaction product of adipic acid, diethylene glycol and triol, viscous liquid at normal temperature (25C), viscosity (75C): about 20 lO00 cp) 35 parts Palmitic Acid 0.5 parts Methyl Ethyl Ketone l~0 parts Methyl Isobutyl Ketone 380 parts Toluene 380 parts Subbing Solution C V described above was prepared, but a white turbid solution was obtained. The subbing solution thus obtained was coated onto a polyethylene terephthalate film (having a thickness of 23 jum) in a dry thickness of 1.5 ~m.
The coated layer was dried at ~0C for lO secs. at an air flow of 2.5 kl/cm2/sec. However, this subbing layer C V was uneven *Trade ~ark - :~093905 1 in thickness and takiness rem~ined at the thickly coated portions, which resulted in adherence around a pass roll upon winding up. The film was not suitable for overall production of a tape.
On the other hand, it was found that in case that an amorphous linear saturated polyester resin including an aromatic dicarboxylic acid as was used in Examples 1, 2 and 3 of the present invention was used in the subbing layer, such a tackiness problem as in the aforementioned subbing layer CV was not observed, and the amorphous linear saturated polyester was suitable for use in a subbing layer for a magnetic tape.
Comparative Exam~le 6 Subbing Solution C VI (concentration about 5 3 wt% solution) . _ .
Vinylidene Chloride-Acrylonitrile Copolymer ~same as in Example 1) 15 parts Polyurethane Resin (Desmocoll 176, tradename, made by Bayer A.G., polyester polyurethane containing about 0.1~ of -O~ groups specific gravity (20C): 1.23 g/cm2 solution viscosity (20C, 15 wt% methyl ethyl ketone solution): 2-8 poise) 35 parts `~
Palmitic acid 0.5 parts Methyl Ethyl Ketone 190 parts Methyl Isobutyl Ketone 380 parts Toluene 380 parts The aforementioned Subbing Solution C VI was coated onto a polyethylene terephthalate film (having a thickness of 21 ~m) in a dry thickness of 1.5 Jum. The coated layer was dried at 90C for 10 secs. at an air flow of 2.5 kl/m2/sec.
Magnetic Coating Solution A was further coated on the subbing layer C VI in a dry thickness of 4 ~um. Repellency of the magnetic coating solution was observed so that a uniform magnetic recording layer was not obtained.
*Trade Mark B
1~9390S
1 On the other hand r the aforementioned repellency was not observed in case of Subbing Solution I, II and III of Bxamples l, 2 and 3.
In addition, a similar repellency was observed with the composition in which palmitic acid was omitted from the aforementioned Subbing Solution C VI.
It was thus confirmed ~rom the results above that coating of a magnetic coating solution is not good with a subbing solution composition comprising a vinylidene chloride-acrylonitrile copolymer and apolyurethane resin having furtherincorporated therein a higher fatty acid palmitic and comprising the same components (but not having incorporated therein a higher fatty acid palmitic~ as compared to the present invention, so that a smooth surface of a magnetic recording layer was not obtained.
While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.
The composition of the subbing layer in accordance with the present invention is preferably such that the vinylidene chloride-addition polymerizable nitrile copolymer is present in an amount of about 3 to about 60 wt%, preerably 10 to 50 wt %, based on the amorphous linear polyester resin.
The subbing layer of the present invention is coated onto a non-magnetic support using an organic solvent, followed by drying. The dry thickness of the subbing layer is preferably about 0.03 to about 2.0 ym, more preferably 0.2 to 1.5 ym.
The adhesive strength required in the present invention is such that the adhesive strength can be effectively maintained in the atmosphere at temperatures of from -20 to 70C and at a humidity of 80% RH, which means a tensile strength of greater than about 100 g/cm2 at 30C and greater than about g/cm2 at -20C to 0C, at a velocity of 20 cm/min. or less, preferably 10 to 20 cm/min., using a TOM tensile testing machine.
In addition, it is preferred that chlori~e type organic solvents not be used in the present invention, that the drying rate be rapid without using water in the present invention since water evaporates more slowly, and that no harmful substance be released upon heating or the like in the present invention.
1 Further, the subbing layer in accordance with the present invention may, if desired, contain additives to a magne~ic layer as will be later described, such as a dispersing agent, a lubricating agent, an abrasive, an antistatic agent,etc.
It is preferred that the total of these additives be added in an amount of less than 10 wt% based on the subbing layer.
Suitable examples of organic solvents which can be used upon coating include methyl ethyl ketone which is a main component and, in addition, other compatible ketone type solvents such as acetone, methyl isobutyl ketone, cyclohexanone, etc.:
ester type solvents such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, glycol monoethyl ether acetate, etc.;
glycol ether type solvents such ether, glycol dimethyl ether, glycol monoethyl ether, dioxane, etc.; tar type (aromatic hydro-carbon) solvents such as benzene, toluene, xylene, etc.
It is preferred that the aforementioned organic solvent ke used with the mixing ratio of methyl ethyl ketone being about 50 to about 100 wt%, more preferably 80 to 95 wt%. About 10 to about 50 parts by weight of the copolymer based on 100 parts by weight of the polyester resin are mixed, and dissolved in organic solvent at a concentration of the above two components of about 0.8 to about 5% by weight, as a coating solution for subbing layer.
As methods of coating the subbing layer of the present invention onto a non-magnetic support, there are utilized air doctor coating, blade coating, air knife coating, squizz coating, immersion coating, reverse roll coating, transfer roll coating, gravure coating , kiss coating, cast coating, spray coating, etc.
It is also possible to use other methods, the details of which are described in Coating Kogaku (Coating Technology), pages 253 - 277, 1 March 20, 1971, published by Asakura Shoten, Japan.
Drying conditions after coating the subbing layer are performed at temperatures of less than about 100C, preferably 70 to 100C, more prefera~ly 80 to 90C, using an ir flow of 2 ,Sec 2 ~ec about 1 to about 5 kl/m ~ preferably 2 to 3 kl/m~, and in a period of time of about 2 to about 10 seconds.
As this non-magnetic support, polyesters such as polyethylene terrephthalate, polyethylene-2,6-naphthalate and polybutylene terephthalate are employed as materials thereof.
A polyester film subjected to biaxial stretching is preferred, with the stretching degree in the length direction being about 3 to about 6 times and with the stretching degree in the width direction being about 1.2 to about 4 times. A preferred ratio of the stretching in the length to stretching in the width direction is a stretching ratio more than 1Ø
A thickness o~ these non-magnetic supports is about 3 to about 100 ~m in the case of a film, a tape or a sheet, more preferably 5 to 50 ym, and in case of disk or card a thickness of about 0.5 to 10 mm is best used. In the case of a drum, the shape is rendered cylinder like and determined depending upon the recorder to be used.
The subbing layer in accordance with the present invention is particularly effective when the non-magnetic support is in the shape of a film, a tape or a sheet.
The aforementioned non-magnetic support may have a back coating on the surface opposite to the magnetic layer, for the purpose of static prevention, print-through prevention, or the like.
The useful back coating procedures are described in, for example, U.S.Patents 2,804,401; 3,293,066; 3,617,378;
` 1~93905 t 3,062,676; 3,734,772; 3,476,596; 2,643,048; 2,803,556; 2,887,462;
2,923;642; 2,997,451; 3,007,892; 3,041,196; 3,115,420; 3,166,685 and 3,761,311; etc.
Processes of producing a magnetic material used in forming a magnetic recording layer of the present invention are described in Japanese Patent Publications 15/60; 26794/64;
186/68; 28043/72; 28045/72; 28046/72; 28048/72; 31445/72; 11162/73;
21331/73 and 33583/73; Soviet Patent 308,033, etc. in detail.
~ The magnetic materials described in the above patents mainly comprise ferromagnetic powders, a binder and a coatin~ solvent, and may additionally optionally contain additives such as a dispersing agent, a lubricating agent, an abrasive, an antistatic agent, etc.
Examples of ferromagnetic powders which can be used in accordance with the present invention include known ferro-magnetic powders suchas ~-Fe2O3, Fe3O4, Co-containing Fe3O4, Bertholi~e compounds of ~-Fe2O3 and Fe3O4 (of the formula FeOx, 1.33 <x <1.50), Bertholide compounds of Co-containing ~-Fe2O3 and Fe3O4 (of the formula FeOx, 1.33 ~x <1.50, CrO2, Co-Ni alloys, Co-Ni-P alloys, Co-Ni-B alloys, Co-Ni-Fe alloys, Co-Ni-Fe-P alloys, Co-Ni-Fe-B alloys, Co-Ni-Zn alloys, Co-Ni-Cr-P alloys, Co-Ni-Cr-B alloys, Fe-Mn-Zn alloys, Fe-Co-Ni-Cr alloys,etc., as are specifically described in Japanese Patent Publications 5009/64, 10307/64, 14090/69, 18372/70, 22513/72, 22062/72, 28466/71, 38755/71, 4286/72, 12422/72, 17284/72, 18509/72, 18573/72, 39120/73 and 39639/73, U.S.Patents 3,026,215; 3,031,341; 3,100,194; 3,242,055 and 3,389,014;
British Patents 752,659; 782,762 and 1,007,323, French Patent 1,107,654; German Patent Application (OLS) 1,281,334, etc.
These ferromag~etic powders have a particle size , 105~3~0S
1 f about 0.2 to about 2 microns (length) preferably less than 1.5 micron and a length/width ratio of about 1/1 to about 20/1, preferably more than 5/1.
Examples of binders which can be used in the present invention include a thermoplastic resin, a thermosetting resin or a reactive resin (all of which are known and are conventional) or a mixture thereof.
Preferred thermoplastic resins include those having a softening point of about 150C or less and an average molecular weight of from about 10,000 to about 200,000, and a polymerization degree of about 2~0 to about 2000, examples of w~ich include, a vinyl chloride-vinyl acetate copolymer, a vinyl chloride-vinyli-dene copolymer, a vinyl chloride-acrylonitrile copolymer, an acrylic acid ester-acrylonitrile copolymer, an acrylic acid ester-vinylidene chloride copolymer, an acrylic acid ester-styrene copolymerr a methacrylic acid ester-acrylonitrile copolymer, a methacrylic acid ester-vinylidene chloride copolymer, a methacrylic acid ester-styrene copolymer, a urethane elastomer, polyvinyl fluoride, a vinylidene chloride-acrylonitrile copolymer, a butadiene-acrylonitrile copolymer, a polyamide resin, a poly-vinyl butyral, a cellulose derivative (e.g., cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, etc.), a styrene-butadiene copolymer, a polyester resin, a chlorovinyl ether-acrylate copolymer, various synthetic rubber type thermoplastic resins mixtures thereof, etc.
Examples of these resins are styrene-butadiene rubber, acrylonitrile-butadiene rubber, chloroprene, rubber, etc. and they are described in ~apanese Patent Publications 6877/62;
12528/64; 19282/64; 5349/65; 20907/65; 9463/66; 14059/66;
16985/66; 6428/67; 11621/67; 4623/68; 15206/68; 2889/69;
` 1093905 1 17947/69; 18232/69; 14020/70; 14500/70; 18573/72; 22063/72;
22064/72; 22068/72; 22069/72; 22070/72; 27886/73 and 3121/74;
U.S.Patents 3,144,352; 3,419,420; 3,499,789 and 3,71~,887, etc.
Preferred thermosetting resins or reactive resins have a molecular weight of less than about 200,000 in the state of a coating solution, but the molecular weight thereof becomes essentially infinite due to reactions such as condensation, addition, etc., after coating and drying.
Further, of these resins, resins which do not soften or melt until they are heat decomposed are preferred. Specific examples of these resins are, for example, a phenol resin, an epoxy resin, a polyurethane setting resin, a urea resin, a melamine resin,an alkyd resin, a silicone resin, an acryl type reactive resin, an epoxy-polyamide resin, a mixture of a high molecular weight polyester resin and an isocyanate prepolymer, a mixture of a methacrylate copolymer and a diisocyanate prepolymer, a mixture of a polyester polyol and a polyisocyanate, a urea-formaldehyde resin, a mixture of a low molecular weight glycol/a high molecular wei~ht dLol/triphenylmethane triisocyanate, a polyamine resin, mixtures thereof, etc.
Details on these resins are given in Japanese Patent Publications 8103/64; 9779/65; 7192/66; 8016/66; 14275/66;
18179/ 67,12081/68; 28023/69; 14501/70; 24902/70; 13103/71;
22065/72; 22073/72; 28073/72; 28045/72; 28048/72 and 29822/72;
U.S.Patents 3,144,353; 3,320,090; 3,437,510; 3,597,273;
3,781,210 and 3,781,211, etc.
These binders can be used singly or in combination, and may contain additives. The binders are used ~ithin a range such that the mixing ratio of ferromagnetic powder(s) to the binder is about 10 to about 200 parts b~ weight, _ g _ , . . .
)93905 1 preferably 10 to 100 parts by weight, of the binder per 100 parts by weight of the ferromagnetic powder~s) as weight ratio.
To the magnetic recording layer, a dispersing agent, a smoothing agent, an abrasive, an antistatic agent, etc., can be added, in addition to the aforementioned binder and ferromagnetic powders.
Examples of dispersing agents are a fatty acid having 12 to 18 carbon atoms (RlCOOH wherein Rl is an alkyl or alkenyl group having 11 to 17 carbon atoms) such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, linolic acid, linoleic acid, strearolic acid, etc.; metallic soaps consisting of alkali metal (~i, Na, K, etc.) salts or alkaline earth metal (Mg, Ca, Ba) salts of the aforementioned fatty acids, fluorine- `
containing compounds of the aforementioned fatty acid esters (e.g., C8F17OOC4 - SO3Na); lecithin; trialkylpolyolefin oxy quaternary ammonium salts (~herein the alkyl group has 1 to 5 carbon atoms and the olefin is ethylene, propylene, etc.), etc.
In addition, a higher alcohol having 12 or more carbon atoms such as lauryl alcohol, tridecyl alcohol, myristyl alcohol, pentadecyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, linoleyl alcohol, and sulfonic acid esters of these higher alcohols, such as sodium stearyl alcohol sulfate (C18H32OSO3Na), etc., can also be used. These dispersing agents are employed by adding within a range of from about 0.5 to about 20 parts by weight per 100 parts of the binder. Details are given in Japanese Patent Publications 28369/64, 17945/69, 7441/73, 15001/73, 15002/73, 16363/73 and 4121/75, U.S.Patents 3,387,993 and 3,470,021, etc.
, 1 Examples o~ lubricants which can be used include a silicone oil such as a dialkyl polysiloxane (wherein the alkyl group has 1 to 5 carbon atoms), a dialkoxy polysiloxane (whe:rein the alkoxy group has 1 to 4 carbon atoms), a mono-alky:L monoalkoxy~polysiloxane (wherein the alkyl group has 1 to 5 carbon atoms and the alkoxy group has 1 to 4 carbon atoms), phenyl polysiloxane, a fluoroalkyl polysiloxane (wherein the alkyl group has 1 to 5 carbon atoms~, etc.; electro-conductive powders such as graphite, etc.; inorganic powders such as molybdenum disul~ide, tungsten disulfide, etc.; plastic powders such as polypropylene, a polyethylene-vinyl chloride copolymer, polytetrafluoroethylene, etc.; an a-olefin polymer; unsaturated alphatic hydrocarbons liquid at normal temperature (compounds -having an a-olefinic double bond attached to the carbon at the terminal thereof, about 15 to about 20 carbon atoms); a fatty acid ester comprising a monobasic fatty acid having 12 to 20 carbon atoms and a monovalent alcohol having 3 to 12 carbon atoms;
etc. These lubricants are added in an amount of about 0.2 to about 20 parts by weight per 100 parts by weight of binder. These lubricants are described in detail in Japanese Patent Publications 23889/68, 40461/71, 15621/72, 18482/72, 28043/72, 30207/72, 32001/72, 7442/73, 14247/74 and 5042/75, U.S.Patents 3,470,021;
3,492,235; 3,497,411; 3,523,086; 3,625,760; 3,630,772; 3,634,253;
3,542,539 and 3,687,725. IBM Technical Disclosure Bulletin, Vol. 9, No. 7 page 779 (December 1966), ELEKTRONIK,1961, No. 12, page 380, etc.
As abrasives there are used those which are generally employed in this art which include fused alumina, silicon carbide, chromium oxide, corundum, artificial corundum, diamond, artificial diamond, garnet, emery ~main components: corumdum and -~ 10'33905 1 magnetite), etc. The abrasives have an average particle size of about 0.05 to about 5 ,u, preferably 0.1 to 2 ~. These abrasives are added in an amount of about 0.5 to about 20 parts by weight per :lO0 parts by weight of the binder. Details thereon are given in Japanese Patent Publications 18572/72, 15003/73 and 15004/73 (U.S.Patent 3,617,378), 39402/74 and 9402/75, U.S.Patents 3,007,807; 3,041,196; 3,293,066; 3,630,910 and 3,687,725, British Patent 1,145,349, German Patent 853,211 and 1,101,000, etc.
Examples of antistatic agents which can be used include electroconductive powders such as carbon black, carbon black graft polymers, e.g., a reaction product of a copolymer of carbon black and an acrylate, methacrylate, vinyl chloride or styrene polymer which is prepared by graft polymerization, etc.;
natural surface active agents such as saponin, etc.; nonionic surface active agents such as alkylene oxide type, glycerine type, glycidol type, etc. surface active agents; cationic surface active agents such as higher alkylamines, quarternary ammonium salts, pyridine or other heterocyclic ring compounds, phosphonium or sulfonium, etc. surface active agents; anionic surface active agents containing an acid group such as a carboxylic acid, sulfonic acid, phosphoric acid, sulfuric acid ester, phosphoric acid ester group etc. surface active agents; amphoteric surface active agents such as amino acid, amino-sulfonic acid, sulfuric acid or phosphoric acid esters of amino alcohols, etc. A
suitable amount of the elctroconductive powder is at least about 10 % by weight, preferably 0.1 to 8 % by weight, and of the surface active agent is at least about 10 % by weight, preferably 0.1 to 7 % by weight, each based on the weight of ferromagnetic powder.
Some surface ac~ive agents which can also be used as 1 antistatic agents are described in Japanese Patent Publications 22726/71, 24881/72, 26882/72, 15440/73 and 26761/73, U.S.Patents 2,271,623; 2,240,472; 2,288,226; 2,676,122; 2,676,924; 2,676,975;
2,69L,566; 2,727,860; 2,730,498; 2,742,279; 2,739,891; 3,068,1~1i 3,15~,484; 3,201,253; 3,210,191; 3,294,540; 3,415;649; 3,441,413;
3,442,654; 3,475,174 and 3,5~5,974, German Patent Application (OLS) 1,942,665, British Patents 1,077,317 and 1,198,450, Oda Ryohei, Kaimen Kasseizai no Gosei to sono Oyo (Synthesis of Surface Active Agents and Their Application), 1964, published by Maki Shoten, A.M. Schwartz & J.W. Perry, Surface Active Agents, 1958, published by Interscience Publication Incorporated, J.P. Sisley, Encyclopedia of Surface Active Agents, Vol. 2, 1964, published by Chemical Publish Company, Kaimen Kasseizai Binran (Handbook of Surface Active Agents), sixth ed., December 20, 1966, published by Sangyo Tosho Kabushiki Kaisha, etc.
These surface active agents may be added singly or in combination. They are used as antistatic agents, but they may also be utilized sometimes for other purposes, for example, for dispersion, improvement of magnetic characteristics, improvement of lubricity or as a coating aid.
The provision of the magnetic recording layer is performed by dissolving the aforementioned composition in an organic solvent and coating the resultant coating solution on the subbing layer of the present invention which is provided on a non-magnetic support.
For kneading (dispersion) of a magnetic coating solution, various kneading machines can be used. For example, there are a two roll mill, a three roll mill, a ball mill, a pebble mill, a trommel, a sand grinder, a Szegvari attritor, a high-speed impeller dispersing machine, a high speed stone mill, a high ,. . .
)9390S
1 speed impact mill, a disper, a kneader, a high speed mixer, a homogenizer, a ultrasonic dispersing machine, etc.
Technology regarding kneading (dispersion) is described in T.C.Patton, Paint Flow and Pigment Dispersion, 1964,published by John Wiley ~ Sons, and also described in U.S.Patent 2,581,41 and 2,855,156.
Coating of the aforementioned magnetic recording layer onto a subbing layer of the present invention is performed in a conventional manner by e.g., by any of the procedures earlier described for coating the subbing layer.
Examples of organic solvents which can be used for coating are ketone type solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.;
alcohol type solvents such as methanol, ethanol, propanol, butanol, etc.; ester type solvents such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, glycol acetate, monoethyl ether, etc.; glycol ether type solvents such as ether, glycol dimethyl ether, glycol monoethyl ether, dioxane, etc.; tar type (aromatic hydrocarbon) solvents such as benzene, toluene, xylene, etc., 2~ which can be used alone or in combination.
The thus formed magnetic layer is dried, i necessary, after subjecting the ferromagnetic powders in the layer provided on the subbing layer to an orientation. If necessary, a surface smoothing treatment can be performed or the material cut into a desired shape, a magnetic recording element thus being produced.
In particular, it has been found that if a surfacé smoothing treatment of the magnetic recording layer is performed, a magnetic recording element having a smooth surface and excellent abrasion resistance can be obtained.
In this case, the magnetic field for orientation is ~0939~5 I about 500 to 2000 Gauss (direct current or alternating current), drying is at about 50 to 100C, preferably 70 to 100C, more preferably 80 to 90C and during drying air is blo~n on the A element at an~ lr flow of about 1 to about 5 kl/m2~, preferably 2 to 3 kl/m2~, with the drying time being about 30 seconds to 10 minutes, preferably 1 to 5 mins.
The direction the orientation of the magnetic material is determined depending upon its use. That is, in the case ofa sound tape, a compact video tape, a memory tape, etc., the direction for orientation is parallel to the longitudinal direction of the tape; in the case of a video tape for broadcast-ing, orientation is performed at an angle of 30 to 90C to the longitudinal direction.
Methods for orientation of magnetic powders are also described in the following patents: U.S.Patents 1,949,840;
2,796,359; 3,001,891; 3,172,776; 3,416,949; 3,473,960 and 3,681,138 and Japanese Patent Publications 3427/57, 28368/64, 23624/65, 23625/65, 13181/66, 13043/73 and 39722/73, etc.
~ A surface smoothing treatment can be performed by calendering after drying using a smoothening sheet ~fter coating, etc., as is described in U.S.Patents 2,688,567; 2,- 30,32. and 3,783,023, German Patent Application (OLS) 2,405,222, Japanese Patent Applications (OPI) 53631/74 and 10337/75, etc. `--It has been ~onfirmed that the magnetic recording element obtained in accordance with the method of the present invention as explained above has strong adherance between the magnetic recording layer and the polyester support by the provision of the subbing layer, and, further, the present invention provides a method which does not cause blocking at the edges of a wide sheet or tackiness problems upon coating a wide sheet.
~)9390S
1 The present invention will now be described in more detail with reference to Examples and Comparative Examples hereinbelow. It can easily be understood that components, ratios, the order of operations or the like shown herein can be modified without departing fro~ the spirit and scope of the present invention.
Accordingly, the present invention is not to be limited to the examples hereinbelow.
All parts in the examples and comparative examples below are by weight.
Example 1 Onto a polyethylene terephthalate film (22 ,um thick) Subbing Solution I having the following formulation was uniformly coated in a 0.4 pm dry thickness.
Subbing Solution I (concentration : 2 wt% solution) Amorphous Linear Saturated Polyester (terepolymer of isophthalic acid, sebacic acid and ethylene glycol(l:l:4.2 molar ratio) average molecular weight: 17000, limiting viscosity (30C., 0.5% solution of phenol/
tetrachloroethane=6/4): 0.54 70 parts Copolymer of Vinylidene chloride and Acrylonitrile (nitrogen content: 5.1g, viscosity of - solution (25C., 2 wt% dimethyl formamide solution): 2.2 cp) 30 parts Solvent Mixture of Methyl Ethyl Xetone and Cyclohexane (9 : 1 volume)5000 parts The coating was dried at 80C. for 7 seconds in an air flow of 2.5 kl/m2/sec. to form a subbing layer.
Four specimens of the polyethylene terephthalate film having the subbing layer aforementioned were prepared. Onto the subbing layer of each of the specimens, the following four kinds of Magnetic Coating Solutions A, B, C and D were coated, respectively, in a dry thickness of 8 ~m. After orientation in a ~Q939(~5 1 direct current magnetic field of 1500 ~auss and then drying for 3 mins. at 90 to 95C in an air flow of 3 kl/m2/sec., the films were slit to a 1/~ inch width to obtain magnetic tapes, which were identified as Sample Nos. I-A, I-B, I~C and I-D, respectively.
Magnetic Coating Solution A
Magh~mite ( ~-Fe2O3, Hc = 295 Oe, particle size: 0.~3 x 0.03 x 0.5 ~m)100 parts Vinyl Chloride-Vinyl Acetate Copolymer (copolymerization ratio: 75/25~wt%), molecular weight: 450) 25 parts Polybutyl Acrylate (molecular weight:
lQ about 450) 5 parts Carbon Black (particle size: about 40 ~m) 7 parts Dimethyl Polysiloxane (Degree of polymerication;
about 60) 0.3 part Methyl Ethyl Ketone/Methyl Isobutyl Ketone (1/1 volume) solvent mixture300 parts Magnetic_Co_ting Solution B
Ferromagnetic Fe-Co-Ni Alloy Powders (Hc= 600 Oe, particle size: 0.03 x 0.03 x 0.3 ~m) 100 parts Polyurethane Resin (reaction product of polyethylene adipate and m-xylene diisocyanate, (1.2: 1 molar ratio) molecular weight: 130,000) 15 parts Alkyd Resin (reaction product of glycerine, terephthalic acid and a non-drying oil, (1.2: 2 : 0.5 molar ratio), hydroxyl value:l30, oil length: 29 %) 7 parts Polyisocyanate (a 75 wt% butyl acetate solution of the reaction product of 1 mol of trimethylol propane and 3 mols of 2,4-tolylene diisocyanatel tradename "Desmodur~-75", manufactured by Bayer A.G.) 7 parts Lecithin 1 part Trifluoroethylene chloride 0.5 parts Butyl Acetate 320 parts 10~3905 1 Magnet_c Coatlng Solution C
Co-containing Magetite (Hc = 550 Oe, particle size : O.04 x O.04 x O.6 ~m) 100 parts Vinyl Chloride-Vinyl Acetate Copolymer (copolymerization ratio: 75/25 (wt%), polymerization degree:450) 10 parts Butyl Acrylate-Acrylonitrile Copolymer (copolymerization ratio: 78/22 (wt~), polymerization degree:900) 26 parts Polyisocyanate (same as Magnetic Coating Solution B) 5 parts . Lecithin 1 part Oleic Acid 1.5 part Carbon Black (particle size: about 80 ~m) 7 parts Butyl Acetate/Toluene (1/1) Solvent Mixture 300 parts Magnetic Coating Solution D
Magemite ( ~-Fe2O3, Hc = 295 Oe, particle size: 0.03 x 0.03 x 0.5 lum) 100 parts Nitrocellulose (viscosity: RS 1/2, nitrogen content: 11.8 to 12.20, molecular weight: 30,000) 10 parts Polyether-type Polyurethane Prepolymer (the reaction product of 1,4-oxybutylene glycol and toluene diisocyanate (1.3: 1.6 molar ratio), which has an -NCO group at the terminals thereof molecular weight: 2,000) 20 parts Lecithin 1 part amyl Stearate 0.3 part Carbon Black (particle size: about 50 ~um) 5 parts Polyamine( 4,4'-methylenebis-2-chloroaniline) 2 parts Butyl Acetate/Methyl Ethyl Ketone (1/1 volume) Solvent Mixture280 parts .
lQ939~)~
1 Comparative Example 1 Subbing Solution Cl (concentration: 2 wt % solution) Amorphous Polyester Resin (terpolymer of terephthalic acid, ethylene glycol and triethylene glycol(l: 1.8 : 0.5 molar ratio), softening point: 65C) 97 parts Polycarbonate Resin (bisphenol A type*, molecular weight: 40,000) 3 parts Methyl Ethyl Ketone/Cyclohexane (9/1 volume) Solvent Mixture 5000 parts ~ IH3 IT ~
Subbing solution CI having the formulation described above was coated on a polyethylene terephthalate film (22 ym thick as in Example l, to a 0.4 ~m by thickness followed by drying as in Example 1. Magnetic Coating Solution A was further coated thereon to a dry thickness of 8 ~m, subjected to orientation treatment, and dried and slit in a 1/4 width all as in Example 1. Thus, a magnetic tape was obtained, which was identified as Sample No. ¢I-A.
With respect to Sample Nos. I-A, I-B, I-C, I-D and CI-A, a friction pull test(stripping-off at an angle of 180 ) was performed (JIS K6744-1963, ASTM D903-49(1965)), in which a cellophane adhesive tape (~IS Z1522) was uniformly adhered to the magnetic layer of each magnetic tape 1/4 inch wide and the friction pull strength at an angle of 180 (g/cm) was measured at various temperatures using a TOM tensile testing machine. The results are shown in Table 1 below.
-- 19 -- ' , 1 Table 1 Sample No. Friction Pull Strength at 180 (g/cm) _ I-.A 30 30 40 70 118 45 I~C 40 45 47 82 140 105 It can be seen from the results above that the samples obtained in accordance with Example 1 (Sample Nos. I-A, I-B, I-C
and I-D~ had a good 180 friction pull strength, that is, good adhesive property, whereas the sample obtained in accordance with Comparative Example 1 (Sample No. CI-A) showed a poor adhesive property as a whole, in particular, a poor adhesive property at low temperature.
EXAMP_E 2 A subbing layer having a dry thickness of 0.4 pm was formed as in Example 1 ex~cept that the ratios of the amorphous : linear polyester and the vinylidene-acrylonitrile copolymer of Subbing Solution I used Example 1 were modified as indicated in Table 2 below.
Table 2 Subbing Solution Nos. Polyester/Copolymer (concentration: 2 wt~) _ (wt%? _ _ II 100~0 ' IV 80/20 VI
Onto each of these subbing layers, Magnetic Coating .
i, , , , , .,. .~ . . . . ; ..
~093~5 1 Solution C was uniformly coated in a dry thickness of 10 ~m.
After orientation at a direct current magnetic field of 1500 Gauss and then dryina at 90C for 8 mins. at an air flow of 2.5 kl/m2/sec., the films were slit to a 1/4 inch width.
Magnetic tapes were thus obtained which were identified as Sample Nos. II-C, III-C, IV-C, V-C, VI-C and VII-C.
A friction pull strength at an angle of 180 of each of the samples was measured at 25C as in Example 1, the results of which are shown in Table`3 below.
Table 3 Sample Nos.Friction Pull Strength at 180 (25C) _ (~/cm3 It can ~e seen from the results above that Sample Nos.
II-C, VI-C and VII-C were considerably inferior to Sample Nos.
III-C, IV-C and V-C; good results were obtained when the ratio of the vinylidene chloride-acrylonitrile copolymer incorporated in the amorphous linear polyester resin was 10 to 50 wt %.
Example 3 Subbing Solution VIII !concentration: about 3 wt% solution) Amorphous ~inear Saturated Polyester ~terpolymer of terephthalic acid, ethylene glycol and tri-ethylene glycol(l: 2 : 0.4 molar ratio), average molecular weight:l9,000, softening point: 120C, solubility parameter: 9.1) 85 parts Vinylidene Chloride-Acrylonitrile Copolymer (nitrogen content: 1.5%, specific viscosity (25C, 1 wt% tetrahydrofuran solution): 1.5)15 parts Methylethyl Ketone/Tetrahydrofuran (8/2 volume) Solvent Mixture 3000 parts .,~
.
~093905 1 Subbing Solution VIII described above was uniformly coated onto a polyethylene terephthalate film (having a thickness of 36 ym) in a dry thickness of 1.5 ~um. After drying at 85C for 5 secs. at an air flow of 2.5 kl/m /sec., Magnetic Coating Solution A(see Example 1) was further coated thereon in a dry thickness of 8 ,um, and subjected to orientation at a direct current magnetic field of 1500 Gauss, followed by drying at 90 to 95C for 3 mins, at an air flow of 3 kl/m2/sec. The film thus obtained was slit into a 1/4 inch width. A magnetic tape was obtained which was identified as Sample VIII-A.
Comparative Example 2 Subbing Solution CII (concentration: about 3 wt% solution) Amorphous Linear Saturated Polyester (same as in Subbing Solution VIII)85 parts Vinyl Chloride-Vinyl Acetate Copolymer (copolymerization ratio: 87/13 (wt~), polymerization degree: 420)15 parts ~ethyl Ethyl Ketone/Tetrahydrofuran (8/2 volume) Solvent Mixture3000 parts A magnetic tape was prepared using Subbing Solution C II described above as in Example 3, which was identified as Sample C II-A.
Comparative Example 3 Subbing Solution C III(concentration: about 3 wt% solution) Amorphous Linear Polyester(same as in Example 3) 85 parts Epoxy Resin (the reaction product of epichloro-hydrin and diphenyl propane, epoxy equivalent: 470, molecular wei~ht: 1,000 "Epikote*1001", trade name, produced by Shell Chemical Co.,~td.)15 parts Methyl Ethyl Ketone/Tetrahydrofuran (8/2 volume) Solvent Mixture 3000 parts *Trade Mark 1t~93905 1 A magnetic tape was prepared using Subbing Solution C III described above as in Example 3, which was identified as Sample C III-A.
Comparative Example 4 Subbing Solution C IV(concentration: about 3 wt% solution) -, Amorphous Linear Polyester (same as in Example 3) 85 parts Straight Chain Polyurethane (terpolymer of adipic acid, 1,4-butanediol and diisocyanate (1: 1 : 0.2 molar ratio) molecular weight: 36,000) 15 parts Methyl Ethyl Ketone/Terahydrofuran (8/2 volume) Solvent Mixture 3000 parts A magnetic tape was prepared using Subbing Solution C IV as in Example 3 which was identified as Sample C IV-A.
With respect to Samples VIII-A, C II-A, C~III-A and C IV-A obtained in accordance with Example 3, and Comparative Examples 2, 3 and 4, the friction pull strength (g/cm) at an angle of 180 was measured at various temperature, the results of which are shown in Table 4 below. The measurement was performed as in Example 1.
Table 4 Sample Nos. Friction Pull Strength at 180 (g/cm) ; VIII-A 30 33 40 77 120 60 As can be seen from the results above, Sample VIII-A
had a stable adhesive strength as in Samples I-A, I-B, I-C
and I-D, without a remarkable decrease in adhesive property at a temperature range of from -20C to 70C. On the other hand, Samples C II-A, C III-A and C IV-A showed a poor adhesive .,. ~ .
- 1093~1~S
1 strength, of 40 to 60 g/cm, even at room temperature (30C), which was l/2 that of Sample VIII-A. In particular, the adhesive strength of Sample C III-A was abnormally low at low temperatures (-20C to 0C), i.e., 2 to lO g/cm; thus, good adhesive strength as observed in the subbing layers obtained in accordance with the present invention could not be obtained.
From these results it was confirmed that the composition of the subbing layer in accordance with the present invention, i.e., the two component mixture of an amorphous linear saturated polyester and a vinylidene chloride-an addition polymerizable nitrile copolymer, possesses extremely superior characteristics as compared to an amorphous linear saturated polyester and another resin.
Comparative Example 5 Subbing Solution C V (concentration: about 5.3 wt% solution) Vinylidene Chloride~Acrylonitrile Copolymer (same as in Example l)15 parts Polyester Resin ("Desmophen*2200", tradename, made by Bayer A.G.: the reaction product of adipic acid, diethylene glycol and triol, viscous liquid at normal temperature (25C), viscosity (75C): about 20 lO00 cp) 35 parts Palmitic Acid 0.5 parts Methyl Ethyl Ketone l~0 parts Methyl Isobutyl Ketone 380 parts Toluene 380 parts Subbing Solution C V described above was prepared, but a white turbid solution was obtained. The subbing solution thus obtained was coated onto a polyethylene terephthalate film (having a thickness of 23 jum) in a dry thickness of 1.5 ~m.
The coated layer was dried at ~0C for lO secs. at an air flow of 2.5 kl/cm2/sec. However, this subbing layer C V was uneven *Trade ~ark - :~093905 1 in thickness and takiness rem~ined at the thickly coated portions, which resulted in adherence around a pass roll upon winding up. The film was not suitable for overall production of a tape.
On the other hand, it was found that in case that an amorphous linear saturated polyester resin including an aromatic dicarboxylic acid as was used in Examples 1, 2 and 3 of the present invention was used in the subbing layer, such a tackiness problem as in the aforementioned subbing layer CV was not observed, and the amorphous linear saturated polyester was suitable for use in a subbing layer for a magnetic tape.
Comparative Exam~le 6 Subbing Solution C VI (concentration about 5 3 wt% solution) . _ .
Vinylidene Chloride-Acrylonitrile Copolymer ~same as in Example 1) 15 parts Polyurethane Resin (Desmocoll 176, tradename, made by Bayer A.G., polyester polyurethane containing about 0.1~ of -O~ groups specific gravity (20C): 1.23 g/cm2 solution viscosity (20C, 15 wt% methyl ethyl ketone solution): 2-8 poise) 35 parts `~
Palmitic acid 0.5 parts Methyl Ethyl Ketone 190 parts Methyl Isobutyl Ketone 380 parts Toluene 380 parts The aforementioned Subbing Solution C VI was coated onto a polyethylene terephthalate film (having a thickness of 21 ~m) in a dry thickness of 1.5 Jum. The coated layer was dried at 90C for 10 secs. at an air flow of 2.5 kl/m2/sec.
Magnetic Coating Solution A was further coated on the subbing layer C VI in a dry thickness of 4 ~um. Repellency of the magnetic coating solution was observed so that a uniform magnetic recording layer was not obtained.
*Trade Mark B
1~9390S
1 On the other hand r the aforementioned repellency was not observed in case of Subbing Solution I, II and III of Bxamples l, 2 and 3.
In addition, a similar repellency was observed with the composition in which palmitic acid was omitted from the aforementioned Subbing Solution C VI.
It was thus confirmed ~rom the results above that coating of a magnetic coating solution is not good with a subbing solution composition comprising a vinylidene chloride-acrylonitrile copolymer and apolyurethane resin having furtherincorporated therein a higher fatty acid palmitic and comprising the same components (but not having incorporated therein a higher fatty acid palmitic~ as compared to the present invention, so that a smooth surface of a magnetic recording layer was not obtained.
While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.
Claims (10)
1. A process of producing a magnetic recording element comprising a non-magnetic support having provided thereon a subbing layer and further provided thereon a magnetic layer comprising ferromagnetic powders and a binder, which comprises coating a subbing solution at a temperature of 100°C or below in a dry thickness of about 0.03 to about 2.0 µm, drying the coated layer and then coating the magnetic recording layer thereon, said non-magnetic support being a biaxially stretched polyester, and said subbing solution being about 0.8 to 5 wt% concentration as a solid component and comprising an amorphous linear saturated polyester resin containing an aromatic dicarboxylic acid and glycol, a vinylidene chloride-addition polymerizable nitrile co-polymer in an amount of about 10 to about 50 wt% to said polyester resin and an organic solvent mainly composed of methyl ethyl ketone.
2. The process as claimed in claim 1, wherein said methyl ethyl ketone is present in an amount of about 50 to about 100 wt%
based on total wt% of the organic solvent.
based on total wt% of the organic solvent.
3. The process as claimed in claim 2, wherein said organic solvent includes at least one member selected from the group consisting of ketone type solvents, ester type solvents, glycol ether type solvents and tar type solvents in an amount up to about 50 wt% of said organic solvent.
4. The process as claimed in claim 1, wherein said amorphous linear saturated polyester resin comprises said
4. The process as claimed in claim 1, wherein said amorphous linear saturated polyester resin comprises said
Claim 4 continued:
aromatic dicarboxylic acid and said glycol with the molar ratio of said aromatic dicarboxylic acid and said glycol ranging from 2:1 to about 3:1.
aromatic dicarboxylic acid and said glycol with the molar ratio of said aromatic dicarboxylic acid and said glycol ranging from 2:1 to about 3:1.
5. The process as claimed in claim 4, wherein said polyester resin further contains about 5 mole% or less of other dicarboxylic acids having less than 13 carbon atoms and selected from the group consisting of aliphatic saturated dicarboxylic acids, aliphatic unsaturated dicarboxylic acids and oxydicarboxylic acids.
6. The process as claimed in claim 4, wherein said aromatic dicarboxylic acid has from about 8 to about 18 carbon atoms, and said glycol has about 2 to about 10 carbon atoms.
7. The process as claimed in claim 1, wherein said vinylidene chloride-addition polymerizable nitrile copolymer is a vinylidene chloride-acrylonitrile copolymer or a vinylidene chloride-methacrylonitrile copolymer.
8. The process as claimed in claim 1, wherein said vinylidene chloride-addition polymerizable nitrile copolymer has a nitrogen content ranging from about 1 to about 6 %.
9. The process as claimed in claim 1, wherein said coating of the subbing layer is under drying conditions of at a temperature of less than about 100°C, using an air flow of about 1 to about 5 kl/m2/sec, and within a period of about 2 to about 10 seconds.
10. The process as claimed in claim 1, wherein said dry thickness is 0.2 to 1.5 µm.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP50118541A JPS589488B2 (en) | 1975-10-01 | 1975-10-01 | Jikikiroktainoseiho |
| JP118541/75 | 1975-10-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1093905A true CA1093905A (en) | 1981-01-20 |
Family
ID=14739134
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA262,503A Expired CA1093905A (en) | 1975-10-01 | 1976-10-01 | Process of producing a magnetic recording element |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS589488B2 (en) |
| CA (1) | CA1093905A (en) |
| DE (1) | DE2644494A1 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS53116113A (en) * | 1977-03-18 | 1978-10-11 | Hitachi Maxell | Undercoating agent for magnetic recording medium |
| JPS5677926A (en) * | 1979-11-28 | 1981-06-26 | Tdk Corp | Magnetic recording medium using cobalt adhesion type iron oxide |
| JPS61151584U (en) * | 1985-03-12 | 1986-09-19 | ||
| DE3637805A1 (en) * | 1985-11-06 | 1987-07-16 | Tdk Corp | MAGNETIC RECORDING CARRIER |
| JPH0542236Y2 (en) * | 1986-10-09 | 1993-10-25 | ||
| JPS63158186U (en) * | 1987-04-07 | 1988-10-17 |
-
1975
- 1975-10-01 JP JP50118541A patent/JPS589488B2/en not_active Expired
-
1976
- 1976-10-01 CA CA262,503A patent/CA1093905A/en not_active Expired
- 1976-10-01 DE DE19762644494 patent/DE2644494A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| DE2644494A1 (en) | 1977-04-14 |
| JPS589488B2 (en) | 1983-02-21 |
| JPS5242703A (en) | 1977-04-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |