Organic fluorine compound

Abstract: An organic fluorine compound represented by the general formula wherein Rf, Rf', and Rf'' are each independently a fluoroalkyl terminal group, X, X', and X'' each independently denote a linking group selected from -O-, -S-, -COO-, and wherein R''' denotes H, CH₃ or C₂H₅, h denotes 0 or 1, R, R', and R'' are each independently a hydrocarbon chain comprising a phenylene group having an alkylene group with a total carbon number of 10 or more, or an aliphatic group of the formula -C n H 2n -, -C n H 2n-2 -, -C n H 2n-4 or wherein n is an integer of 10 or more, and k, l and m are each an integer of 1 or more, with the provisio that k + l + m is an integer of 10 or more, and Rn, Rn', and Rn'' are each independently a hydrogen atom, an aryl group, or an aliphatic alkyl group of a carbon number of 8 or more, and o, p; q, i, j and k each denote 0 or 1, with the provisio that o+i = p+j = q+k = 1 and o+p+q ≧ 1 .

Description: The present invention relates to an organic fluorine compound suitable as a dispersing agent for dispersing fine particles of various metals, metal oxides, metal salts, fluorocarbons, fluorine-containing resins, and the like into various resins or the solutions thereof. In more particular, it relates to an organic fluorine compound which is capable of imparting such properties as water repellency, oil repellency, soil resistance, mold release, and rust prevention to the surface of articles obtained from such dispersions and is particularly excellent in dispersion stability. DESCRIPTION OF THE PRIOR ART A ferromagnetic metal film type magnetic recording medium obtained by forming a magnetic layer of cobalt, nickel, iron or an alloy comprising said metals as the principal component by a vacuum film-forming process, such as vacuum vapor deposition, sputtering and ion plating, on a substrate, e.g. a film of polymer such as polyester and polyimide, aluminum alloy sheet, glass sheet, etc. can potentially have a drastically increased recording density. To realize such increased density, however, it is necessary to make the magnetic layer very thin and at the same time to make the surface of the medium as flat as possible. However, since these measures act toward lowering the endurance reliability of said medium, a variety of measures have been investigated with the aim of improving the endurance reliability. For example, in a magnetic disc unit used in the external memory of electronic computers, a so-called contact-start-stop (CSS) system is in use wherein generally the magnetic head floats above the magnetic disc surface when the disc is in operation and contacts with the disc surface during stoppage. For such a system, a method have been proposed wherein fine irregulalities (protruded parts) are formed on the disc surface, a ferromagnetic metal thin film is then formed thereon, and a protective layer and a lubricant layer are further provided on the ferromagnetic metal thin film, the protective layer comprising graphite, SiO 2 etc. as the main component and the lubricant layer comprising a perfluoropolyether having modified or unmodified molecular terminals. In magnetic coating materials used in magnetic tapes, magnetic discs, magnetic cards, etc., the dispersibility and the dispersion stability of ferromagnetic fine particles are important factors in manifestation of magnetic properties. Further, when ferromagnetic metal fine particles comprising iron, its alloy, or the like is used as such ferromagnetic fine particles, the storage stability after magnetic coating formation, viewed from the point of rust prevention, is also a important factor. Previously, therefore, hydrocarbons having polar groups, e.g. higher fatty acids or their sulfuric esters, lecithin, and aliphatic phosphoric acid esters, have been used as as surface active agent with the aim of enhancing dispersibility or storage stability. In order to increase the recording density of a ferromagnetic metal thin film type magnetic recording medium, it is necessary to reduce the floating distance of the magnetic head. In such a case, if the surface configuration of the magnetic disc is improved by reducing the height of protruded parts on the disc surface, it causes lowering of CSS durability and at the same time causes a so-called adsorption phenomenon wherein the lubricant on the disc surface gathers between the magnetic head and the disc during stoppage of the disc unit and resultantly the magnetic head sticks to the disc surface. To solve such problems, therefore, it is important that the lubricant on the disc surface forms a coating layer composed of the lubricant on the protective layer surface and can be easily sheared between the lubricant molecules at the contact point of these coating layers, namely at the sliding surface between the disc and the magnetic head. Since a Perfluorpolyether used as a lubricant is covered over almost the whole surface of its molecule with fluorine atoms, it shows a good shearing property between molecules but a weak adhesive force to the disc surface or the magnetic head surface. Although introduction of various polar groups into Perfluorpolyether has been proposed to strengthen the adhesive force to the magnetic head surface, the effect of the introduction of polar groups is not satisfactory because perfluoropolyether has itself a high molecular weight of at least 3000, usually 4000 or more, and the effect of improving disc durability is also not marked. On the other hand, when the molecular weight of perfluoropolyether itself is decreased in order to enhance the efficacy of polar groups, it leads to spin-out due to high speed rotation of the disc and vaporization of the polyether itself because interaction between the molecules is weak. Accordingly, reduction of the molecular weight is difficult to adopt in practice. On the other hand, aliphatic hydrocarbons having polar groups typically represented by stearic acid are excellent in adhesive strength to various surfaces and in disposition toward molecular orientation. However, since they show a stronger interaction between molecules as compared with fluorohydrocarbons, the can hardly give a desired durability wen used as the lubricant. Further, surface active agents for magnetic coating materials previously used have limitation in their dispersibility and, since the surface roughness of the magnetic layer is determined by the dispersibility, they not only are becoming incapable of meeting the recent demand for higher recording density but have difficulties in that these surface active agents bleed out gradually to the magnetic layer surface to deteriorate the practical performance or cause rusting during storage at high temperature to deteriorate the performance. DE-A-3,816,467 discloses an organic fluorine compound to be used for producing a magnetic recording medium according to the following general formula: R f -A-X-B wherein: R f is a perfluoralkyl group having 3-20 C-atoms, A is at least one bivalent functional rest selected from the group consisting of -CH 2 -, -CH=CH-, -CO 2 -, -CONR 1 - and SO 2 NR 1 -, wherein R 1 is a hydrogen atom or an alkyl group having 1 to 10 C-atoms, X represents an alkylene group having 2 to 30 C-atoms and B represents a hydrogen atom or a monovalent functional rest selected from the following group: wherein R 1 and R 1' independently represent a hydrogen atom or an alkyl group having 1 to 10 C-atoms and R 2 represents an alkali metal ion, an earth alkali metal ion, a monovalent or bivalent heavy metal ion, a hydrogen atom or an alkyl group having 1 to 10 C-atoms, and -CONR 3 R 4 , wherein R 3 and R 4 each represent a hydrogen atom, an alkyl group having 1 to 10 C-atoms or an aryl-group having 6 to 18 C-atoms. SUMMARY OF THE INVENTION The object of the present invention is to provide an organic fluorine compound which can solve the difficulties mentioned above. The organic fluorine compound of the present invention is represented by the general formula ; wherein R f , R f ' and R f " are each independently a fluoroalkyl terminal group of a carbon number of 3 or more, a group represented by the general formula C n F 2n-1 , wherein n is an integer of 3 or more or a group represented by the following chemical formulas (a) and (b), X, X' and X", each independently denote a linking group selected from -O-, -S-, -COO-, wherein R‴ denotes H, CH 3 or C 2 H 5 , h denotes 0 or 1, R, R' and R" are each independently a hydrocarbon chain comprising a phenylene group having an alkylene group with a total carbon number of 10 or more, or an aliphatic group of the formula -C n H 2n -, -C n H 2n-2 , -C n H 2n-4 or wherein n is an integer of 10 or more, and k, l and m are each an integer of 1 or more, with the provisio that k + l + m is an integer of 10 or more, and R n , R n ' and R n " are each independently a hydrogen atom, an aryl group or an aliphatic alkyl group of a carbon number of 8 or more, and o, p, q, i, j and k each denote 0 or 1, with the provisio that o+i = p+j = q+k = 1 and o+p+q ≥ 1: BRIEF DESCRIPTION OF THE DRAWING The attached drawing is a sectional view showing the structure of a magnetic recording medium using an organic fluorine compound according to one embodiment of the present invention. PREFERRED EMBODIMENT Example Example 1 In the surface active agent according to the present invention, the fluoroalkyl terminal group may be, for example, C n F 2n+1 -, HCF 2 (CF 2 ) n -, wherein n is an integer of 3 or more, and may be any of straight-chain or branched-chain, saturated or unsaturated one; the fluoroaryl terminal group may be, for example, the aliphatic alkylene group may be, for example, -C n H 2n - , -C n H 2n-2 - , -C n H 2n-4 - , and wherein n is an integer of 10 or more, and k, ℓ and m are each an integer of 1 or more, with the proviso that k+ℓ+m is an interger of 10 or more; the phenylene group having an alkylene group may be for example, wherein ℓ is an integer of 0-4, and m and n are each an integer of 1 or more, provided that ℓ×m+n+6 is an integer of 10 or more; the fluoroalkyl terminal group or the fluoroaryl terminal group are linked with the aliphatic alkylene group or the phenylene group having an alkylene group directly or through various linking groups exemplified below wherein R denotes H, CH 3 or C 2 H 5 . The fluorohydrocarbon chains linked as described above are linked with functional groups directly or through various linking groups exemplified below -O-(CH 2 ) n -, -S-(CH 2 ) n -, and wherein n denotes an integer of 1 or more, and R denotes H, CH 3 or C 2 H 5 . Suitable fluoroalkyl terminal groups are those having a carbon number of 3 or more, preferably 5 or more. Those of a carbon number of 2 or less do not give a good dispersibility and rust prevention effect. Suitable fluoroaryl terminal groups are fluorophenyl groups, fluorobiphenylyl groups, and the derivatives thereof. Suitable hydrocarbon chains are aliphatic groups and phenylene groups having an alkylene group both having a number of total carbon atoms of 10 or more, preferably 12 or more, and the derivatives thereof. When the number of total carbon atoms is 9 or less good dispersibility and rust prevention effect cannot be obtained. The ratio of the atomic group weight of the fluoroalkyl group or the fluoroaryl group to the molecular weight of the surface active agent molecule is desirably in the range of 10-90%, preferably 20-80%. When the ratio is outside the above range, the dispersion stability is poor. Example 2 Preparation of The primary amine can be prepared by reducing an acid amide obtainable by the reaction of a carboxylic acid chloride having a Fluoroalkylderivativeresidue with ammonia with Boran·Tetrahydrofurancomplex (BH 3 ·THF). The secondary Amine can be prepared by reducing with BH 3 ·THF an acid amide obtainable by the reaction of a carboxylic acid chloride having a Fluoralkylderivativeresidue or an aliphatic or aromatic carboxylic acid chloride with a primary amine having a Fluoralkylderivativeresidue or an aliphatic or aromatic primary Amine. The tertiary Amine can be prepared by reacting a secondary Amine having a Fluoralkylderivativeresidue or an aliphatic or aromatic secondary Amine with a halogenide having a Fluoralkylderivative residue or an aliphatic or aromatic halogenide with the aid of sodium carbonate or potassium carbonate. Example 3 Preparation of C 8 F 17 (CH 2 ) 11 NH 2 In a 1ℓ round-bottomed flask was placed 124.6 g (0.20 mol) of Heptadecafluornonadecanoic acid chloride, C 8 F 17 (CH 2 ) 10 COCl, and cooled to 10-15°C. Then, a mixed solution of 25.1 g of an about 28% aqueous ammonia solution and 47.5 g of Pyridine was added dropwise thereto with stirring, over a period of about 2 hours. Thereafter, stirring was continued at room temperature for 6 hours to complete the reaction. The reaction liquid was mixed with 1 ℓ of ethyl acetate, then washed with 5% aqueous hydrochloric acid solution, and further washed repeatedly with distilled water until the pH of the aqueous layer reached 7. The ethyl acetate solution was dried with anhydrous sodium sulfate, the solvent was distilled off under reduced pressure, and the resulting product was recrystallized with methanol to obtain heptadecafluorononadecanoic acid amide. In a 1-ℓ round-bottomed flask were placed 60.3 g (0.10 mol) of the acid amide and 300 ml of THF, and 120 ml (0.12 mol) of 1 molar BH 3 ·THF/THF solution was added dropwise thereto with stirring at room temperature in about 1 hour while high purity nitrogen gas was being passed through the flask. Thereafter, stirring was continued at room temperature for 7 hours to complete the reaction. Then, 100 ml of water was carefully added dropwise to the reaction liquid to effect hydrolysis, and 50 ml of 6N hydrochloric acid was further added. The reaction liquid was then heated to 85-90°C to distill THF away in atmospheric air, and 100 ml of 6N sodium hydroxide solution was added to the liquid to isolate the produced amine. The amine was extracted three times with 300 ml of ether in all. The extract was washed repeatedly with distilled water until the pH of the aqueous layer reached 7, then dried with anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure. The resulting product was recrystallized with methanol to obtain a white solid represented by the formula C 8 F 17 (CH 2 ) 11 NH 2 . The solid was found, based on GPC and organic mass spectrometry, to be a single component containing no starting material and no intermediate product. Example 4 The attached drawing is a diagram showing the basic structure of a magnetic recording medium utilizing the present invention. On the both sides of a non-magnetic support 1, are provided ferromagnetic metal thin films 2 and 2. Further, on the both sides of said ferromagnetic metal thin films 2 and 2, are provided lubricant layers 4 and 4 through the medium of carbon protective layers 3 and 3. The above-mentioned organic compound is made to exist on the carbon protective layers, as such alone or as a mixture thereof with other lubricants, rust preventing agents, etc., in the form of thin layer at a rate of 0.05 - 300 mg (preferably 0.1 - 150 mg) per 1 m 2 of the surface. This may be performed by using conventional dry or wet coating methods. The effect of the present invention can be obtained by forming a lubricant layer containing the organic compound mentioned above on a carbon protective layer. As the carbon protective layer, there may be used carbon thin films the state of amorphous carbon, graphite, diamond, the mixture thereof, or the lamination thereof, obtained by such means as Sputtering and Plasma-CVD. The thickness of the layer is suitably 50 - 500 Å. The ferromagnetic metal thin films may be those of Co-Ni, Co-Cr, Co-Ni-Cr, Co-Ni-P, Fe-Co, Fe-Co-Ni, etc. obtained by means of vacuum vapor deposition, sputtering, ion plating, plating etc. As occasion demands, underlayers of Cr, Ti, etc. may also be provided. The thickness of the ferromagnetic metal thin film including that of the underlayer is suitably 500 - 5,000 Å. Between the ferromagnetic metal thin film and the carbon protective layer, there may also be formed, as occasion demands, thin film of non-magnetic metals such as Cr and Ti or organic plasma-polymerized film, etc. The non-magnetic support may comprise as the principal material glass, ceramic, metals such as Al alloy and Ti alloy, and plastics such as polyesters, polyimides, polyamideimides, polycarbonates, and polyacrylates and, as occasion demands, may have Co-P plating film, polyimide coating, etc. formed on the surface or may be provided with protrusions made by texture finishing or protrusions in the form of fine particles, hills, waves etc. on the surface. The shape of the support may be properly selected according to intended uses including disc, sheet, film, card, drum, and so forth. The surface roughness of the support is suitably 100 - 600 Å in terms of the maximum height, Rmax. Some embodiments of the present invention will be further described in detail below. A non-magnetic substrate 1 was prepared by applying a non-magnetic Ni-P alloy plating 25 µm in thickness onto the surface of an Al alloy plate 95 mm in diameter and 1.2 mm in thickness and forming on the surface by texture finishing protrusions of a mean roughness of 50 Å and a maximum height of 300 Å. Then, a Cr underlayer of 1300 Å thickness and a Co-Ni ferromagnetic metal thin film 2 of 600 Å thickness were formed on the substrate by means of sputtering, and a graphite protective layer 3 of 200 Å thickness was further formed thereon by means of sputtering, the resulting product being named sample Å. Sample B was prepared in the same manner as above but by forming a diamond-like carbon protective layer 3 of 50 Å thickness by means of plasma CVD in place of the graphite protective layer 3. Similarly, sample C was prepared by forming a diamond-like carbon protective layer 3 of 30 Å thickness and sample D by forming no carbon protective layer. The various organic compounds described before were each separately coated on each of the above samples in an amount of 10 mg per 1 m 2 of the surface. These represent Experimental Examples 1 to 6 and comparative Examples 20 to 27. With each specimens of Experimental Examples, CSS determination and head adsorption test were made immediately after the coating and after standing at 90°C for 24 hours. The CSS durability was evaluated in terms of the number of times of CSS at the point of time where the friction coefficient exceeded 1.0 or the number of times of CSS at the point of time where the head crash occurred, and these points of time were taken as the CSS life. In the adsorption test, the disc was allowed to stand at 60°C for 24 hours with a slider fixed thereto and then rotated at room temperature. When the force applied to the slider at the start of the rotation showed an abnormal value, it was regarded as the occurrence of adsorption. Table 1 shows, with respective specimens mentioned above, the details of the specimens and the results of the CSS test and the adsorption test. In the Table, Experimental Examples 20 to 27 are Comparative Examples. Table 1 reveals that when the organic compound has no fluoroalkyl terminal group or no fluoroaryl terminal group or the number of their carbon atoms is 2 or less (Experimental Examples 20 and 21), when the number of total carbon atoms of the hydrocarbon chain is 9 or less (Experimental Examples 22 and 23), when the polar group has a weak adhesive force as in the ester group (Experimental Example 24),d or when the carbon protective layer is very thin or is lacking (Experimental Examples 25 and 26) the intended performances cannot be obtained, whereas when the above conditions are within the scope of the present invention, the results of CSS test and adsorption test are all good. On the other hand, when a perfluoropolyether known to the art was used for the lubricant layer, intended performance could not be obtained. Example 16 Twenty (20) parts each of the organic Fluorine compounds prepared by the methods of Examples 2 and 3 or similar methods were separately dissolved in 1000 parts of Isopropanol, and 100 parts each of ferromagnetic metal (comprising α-Fe) powder was added and dispersed into the respective solutions. The liquid dispersion was then filtered and dried to make the organic fluorine compound of the present invention adhere to the ferromagnetic metal powder surface. As Comparative Examples, ferromagnetic metal powders were subjected separately to the surface treatment in the same manner as described above except for using a hydrocarbon having a polar group known to the art or a surface active agent synthesized separately. These ferromagnetic metal powders (100 parts each) were added respectively to the following composition and thoroughly mixed and dispersed in a ball mill to obtain magnetic coating materials. Teile Polyurethan 10 parts Vinylchlorid-Vinylacetat Copolymer (VAGH) 10 parts Isocyanatsolution (Colorate L) 5 parts Tristearin 0.1 part Methylethylketon 100 parts Toluol 80 parts Cyclohexanon 10 parts These coating materials were each coated and dried on a polyester film of 10 µm thickness with a magnetic field of 2000 Gauss being applied thereto, to give a film thickness of 5 µm and then subjected to calendering and cutting to obtain a magnetic tape. In the present Example, to examine the dispersion stability of the coating material, coating was conducted after the coating material had been allowed to stand for 5 days after the preparation of the material. The respective tapes thus obtained were examined for RF output and video S/N on a video deck. The surface roughness of the magnetic layer was determined with a tracer-Type surface roughness meter. Further, as the storage stability test, the respective tapes were allowed to stand at 60°C and 90% R.H. for 1 month, and then used for recording and regeneration and examined for development of head clogging at the time. The results of these tests are shown in Table 2. The tape numbers shown in parentheses in the Table refer to comparative Examples. Example 17 A magnetic layer of 3 µm thickness comprising Co-containing γ-Fe 2 O 3 magnetic powders dispersed therein was formed on the surface of polyester film of 10 pm thickness. Then, various kinds of back coating were formed on the backside of the film in the following manner. The inventive surface active agents and the surface active agents used in Comparative Example were each separately added to the following composition in an amount of 2 parts each and the resulting mixtures were separately dispersed in a ball mill for 15 hours to prepare back coating liquids. Fluorocarbon resin powder ("Lubron", particle diameter 0.3 µm) 20 parts Carbon black Riß 20 parts Calciumcarbonat 40 parts Polyesterresin 20 parts Methylethylketon 300 parts Toluol 200 parts Cyclohexanon 50 parts Ten (10) days after the preparation of the coating liquids, the liquids were each separately coated to form back coating layers of 0.5 µm thickness. The coated films were then cut to obtain magnetic tapes. These tapes were run on a video deck to examine the initial video S/N and the state of abrasion of the backside after 100 passes. Separately, the initial surface roughness of the tape was determined. The results of these tests are shown in Tables 3 and 4. The tape numbers shown in parentheses in the Tables refer to Comparative Examples. The results shown in Table 3 reveal that when the Fluoroalkyl terminal group or the fluoroacryl terminal group is absent or the number of carbon atoms thereof is 2 or less (Comparative Examples 21 and 22), or when the number of total carbon atoms of the hydrocarbon chain is 9 or less (comparative Examples 23 and 24), the intended performances cannot be obtained, whereas when the above conditions are within the scope of the present invention, the surface roughness, video deck test results, and abrasion test results are all good. Tape No. Surface active agent Video S/N (dB) Abrasion state (after 100 pass) Surface roughness (µm) 2 The one used in No. 1, Tab. 1 +1.0 Good 0.04 Tape No. Surface active agent Video S/N (dB) Abrasion state (after 100 pass) Surface roughness (µm) 9 The one used in No. 1, Tab. 2 +0.8 Good 0.05 (16) Stearic acid 0 Poor 1.0 EFFECT OF THE INVENTION The organic fluorine compound of the present invention is capable of greatly improving the dispersibility of magnetic powders in magnetic coating materials, has also an excellent rust prevention effect on metallic magnetic powders, and exhibits in the present invention a marked dispersing effect even on fluorocarbon resin fine powders, which can be difficultly dispersed with conventional dispersing agents. Moreover, the organic fluorine compound of the present invention exhibits superior performances as a metal surface treating agent, fiber surface treating agent, resin modifiers etc. excellent in water repellency, oil repellency, soil resistance, mold release, rust prevention etc. to those of the prior art. Further, when used in magnetic recording media, the organic fluorine compound of the present invention enables manifestation of good endurance reliability while retaining such performances as CSS durability and head adsorption property, even when the height of surface protrusions is reduced and the surface flatness is thereby considerably enhanced for the purpose of increasing the recording density. Thus, the present invention is of great industrial advantage.

Claims: An organic fluorine compound represented by the general formula wherein R f , R f ' and R f " are each independently a fluoroalkyl terminal group of a carbon number of 3 or more, a group represented by the general formula C n F 2n-1 , wherein n is an integer of 3 or more or a group represented by the following chemical formulas (a) and (b), X, X' and X", each independently denote a linking group selected from -O-, -S-, -COO-, wherein R''' denotes H, CH 3 or C 2 H 5 , h denotes 0 or 1, R, R' and R'' are each independently a hydrocarbon chain comprising a phenylene group having an alkylene group with a total carbon number of 10 or more, or an aliphatic group of the formula -C n H 2n -, -C n H 2n-2 , -C n H 2n-4 or wherein n is an integer of 10 or more, and k, l and m are each an integer of 1 or more, with the provisio that k + l + m is an integer of 10 or more, and R n , R n ', and R n " are each independently a hydrogen atom, an aryl group or an aliphatic alkyl group of a carbon number of 8 or more, and o, p, q, i, j and k each denote 0 or 1, with the provisio that o+i = p+j = q+k = 1 and o+p+q ≥ 1: and An organic fluorine compound according to claim 1, wherein the fluoroalkyl group is selected from C n F 2n+1 - HCF 2 (CF 2 ) n -, wherein n is an integer of 3 or more.

Inventors: KAI YOSHIAKI, SUZUKI TAKASHI, KAI, YOSHIAKI, SUZUKI, TAKASHI
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1989
Main classification: C07C233
IPC codes: C07C235, C07C57, C07C311, C07C233, C07C211, C07C53, C07C59, C07C69, C07C217, G11B5, C07C237