JPH0133494B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a plastic film with excellent antistatic properties and slipperiness. More specifically, the present invention relates to a flexible film that has excellent antistatic properties and slip properties, and has surface characteristics suitable for use as a slip sheet for holding the end face of a magnetic tape leader tape or a magnetic tape coil. Prior Art Various methods have been proposed to reduce electrostatic damage caused by charging of plastic films. One such method is to add and blend a substance with antistatic ability and conductivity to a polymer in order to prevent static electricity on the entire surface and on the polymer. Although this method is certainly superior to the method of applying an antistatic agent to the surface in terms of the durability of the effect, on the other hand, it does not cause coloration under the various heat conditions that occur when forming a film. Furthermore, it is technically extremely difficult to suppress the deterioration of physical properties due to the mixing of additives and to prevent surface defects from occurring due to poor compatibility.Furthermore, surface adhesion due to bleed-out of the above-mentioned additives is extremely difficult. It is also extremely difficult to overcome problems such as increased sexiness, and there are also problems such as unevenness in bleedability. On the other hand, the method of applying a small amount of antistatic agent directly to the film has the advantage of being simple, but has recently been avoided because its effect is temporary and the antistatic agent is likely to fall off. For this reason, research and development of antistatic agents has focused exclusively on carrying out reactive crosslinking of conductive polymers or a portion thereof on the film surface, and various improvements have been made. However, even if the coating film itself is modified to prevent static electricity, it may still lack adhesion to the substrate, especially polyester film, and if too much emphasis is placed on adhesion, the surface will remain sticky. It is virtually difficult to balance these antinomy phenomena. Problems are unlikely to occur especially when polyester films coated with antistatic agents are used statically, but when used in situations where something comes into contact with the surface and causes it to be rubbed. It cannot be said that resin film-forming antistatic agents or antistatic agents that have been modified to have reactive crosslinking properties will necessarily provide sufficient surface properties. For example, leader tapes for magnetic tapes using such antistatic polyester films are fed out and rolled up many times in a cassette, and the environment in which they can be used is 60°C and 80% humidity.
However, under such conditions, blocking phenomenon of the coating layer may occur, or extremely small amounts of magnetism generated from the edge of the magnetic tape due to repeated use of the tape may occur. The powder adheres and accumulates on the coated surface, which has become sticky, and is further transferred to the magnetic tape surface, causing drop-outs and other deterioration of properties. Furthermore, oligomer substances precipitated from the antistatic coating layer also tend to cause scum in a high temperature and high humidity atmosphere. To give one example, when a specific quaternary ammonium salt-containing acrylic conductive resin, polyamine sulfone, polystyrene sulfonate resin, etc. is coated on a polyester film, the desired antistatic ability is developed, but There are many problems in terms of practical properties, such as scum accumulating on the cassette pin under high humidity conditions, transfer to the back side of the film, and because it is sticky, it attracts various types of dust. Therefore, if we try to improve the properties of the coating film and make the surface layer harder, crazes will occur when the surface is rubbed, and eventually they will be rolled into the tape as scrapes, reducing the antistatic ability and causing various problems. develop into trouble. For example, a leader tape obtained by partially hydrolyzing silicon tetrachloride in a lower alcohol and/or ester solvent and coating a polyester film with a coating agent that has excellent antistatic properties. As mentioned above, shavings are likely to be generated. Furthermore, recently, various antistatic agents have appeared in which vinyl and acrylic prepolymers having quaternary ammonium salts or sulfonate salts in their side chains are crosslinked by ultraviolet irradiation or electron beam irradiation. However, none of them have sufficient characteristics for the reasons mentioned above. When considering antistatic films, especially leader tapes for magnetic tapes, from this point of view, film-forming antistatic agents have a problem of durability to varying degrees. The causes of this are abrasion on the front and back sides of the film due to tape feeding and winding, contact abrasion with pins in the cassette, rapid changes in coating film properties under high temperature and high humidity, and adhesion of foreign matter to the adhesive surface, etc. simultaneously or in combination. This seems to be due to the fact that it occurs over time. In this sense, conventional film-forming antistatic agents have been considered superior in durability, and there seems to have been no interest in applying surfactant-type antistatic agents. Purpose of the Invention The present inventor has discovered that the characteristics of magnetic tape leader tape or slip sheet during use, that is, the durability against repeated surface contact and peeling phenomenon, are due to the interface rather than the film to which a film-forming antistatic agent is applied. We thought that a film with an active agent-type antistatic agent and a monomolecular layer on the surface that has antistatic properties would be more suitable, and we conducted extensive studies from this perspective. As a result, although it was not possible to obtain sufficiently satisfactory results with a surfactant alone, it was discovered that by combining a specific surfactant, it was possible to provide extremely excellent characteristics as a leader tape or slip sheet, and the present invention was developed. reached. An object of the present invention is to provide a plastic film with excellent antistatic properties and slipperiness.
Another object of the present invention is to provide a flexible film having surface characteristics suitable for use as a slip seal when pressing the end face of a magnetic tape leader tape or a magnetic tape coil. Structure and Effects of the Invention According to the present invention, a coating composition containing olelimidazoline ethosulfate, polyoxyethylene alkyl phenyl ether, and a fatty acid metal salt is applied to at least one surface of a plastic film. This is achieved by an antistatic film characterized by coating a substance to a thickness that imparts antistatic properties. Among the coating compositions constituting the antistatic film of the present invention, oleyl imidazoline ethosulfate is a compound having the following structure, and its cation percentage is preferably 50 to 90%. Here, R is _CH3 ( _CH2 ) _7CH =CH( _CH2 ) _-7 . In addition, polyoxyethylene alkyl phenyl ether has 8 to 10 repeats of oxyethylene.
(Additional mole number: 8 to 10) is preferable, and those in which the alkyl group is an octyl group to a nonyl group are preferable. Furthermore, HLB (Hydrophile-Lipophile)
Balance) is preferably in the range of 6 to 12. Furthermore, fatty acid metal salts within a range that can be dissolved in water are effective, and ranges in which the number of carbon atoms is too large are excluded. The most desirable ones are _C1 - _C3 fatty acids such as sodium or potassium. If any one of the constituent components of the coating composition is absent, it is impossible to bring out good properties, but when these three specific components work together, an excellent antistatic film can be obtained. For example, if either olelimidazoline ethosulfate or fatty acid metal salt is lacking, the antistatic ability will be insufficient. In particular, if olelimidazoline ethosulfate is missing, the sliding properties under high temperature and high humidity conditions will rapidly decrease, the surface will become more sticky, and when dust is attached, it will be difficult to remove it from the surface. On the other hand, if lower fatty acid metal salts are lacking, the antistatic performance at high temperatures and low humidity will be greatly reduced. In addition, the active ingredient does not penetrate into the film structure at all, and the effect of the agent disappears quickly. In addition, lack of the polyoxyethylene alkyl phenyl ether component causes problems in uniformly coating plastic films, especially polyester films, and in particular, the monomolecular film of the antistatic agent is easily removed by other materials, resulting in poor overall durability. decreases.
That is, it seems that this component plays an important role when the surface is repeatedly contacted, and serves to anchor the monomolecular film to the substrate. An antistatic film suitable as a leader tape and a slip sheet can be achieved by applying the above-mentioned specific mixed composition, but it is actually used as a leader tape of a magnetic tape, in which case it bleeds out from the magnetic layer. In order for the lubricant to exhibit its full effect without causing any interaction even when it comes into contact with the surface coated with this specific composition, it is desirable that the above-mentioned components be in a specific proportion relationship. 77-50% by weight of oleimidazoline ethosulfate, 20-35% by weight of polyoxyethylene alkyl phenyl ether, and 3-3% by weight of a fatty acid metal salt such as potassium acetate.
It can be said that 15% by weight is the optimum condition since it gives the antistatic film of the present invention the best characteristics. Although magnetic tapes outside this range still have certain characteristics, the type of commercially available magnetic tape, i.e., the antistatic agent, wetting agent, etc. contained in the magnetic layer, and the antistatic agent on the surface of the leader tape have some influence. It is difficult to say that it is perfect in terms of reliability, as there may be conflicts between the two. The composition specified in the present invention and the antistatic agent prepared in a more suitable composition ratio can contain 10% of the active ingredient.
It may be applied onto a plastic film, particularly a polyester film, as an aqueous solution or a mixed solution of water and a lower alcohol such as methanol, ethanol, isopropanol, etc. at a concentration of 0.01% by weight. Known coating methods can be used to apply this, such as roll coating, gravure coating, roll brushing, spray coating, air knife coating, impregnation, and curtain methods, which can be used independently or in combination. The amount of application is
It is important to keep the amount to the minimum necessary amount, as it is not only uneconomical to use a large amount unnecessarily, but also only promotes stickiness. As a rough guide, the active ingredient is 0.5g/
^m2 to 0.005g/ ^m2 , and the coating uniformity was measured using JISK6768 on the surface of arbitrarily sampled coated film pieces, and the surface tension showed wettability of 54dyne/cm or more at room temperature. There is no problem if you do. When coating a polyester film, it should be applied during the process of manufacturing the polyester film, that is, immediately after melt extruding and casting polyester, especially polyethylene terephthalate (unstretched film), or either vertically or horizontally. The antistatic composition may be applied in-line at a relatively high concentration to the surface layer of the base material immediately after stretching, or it may be applied off-line to a so-called polyester film that has already been subjected to biaxially stretched crystal orientation treatment. It may also be applied by coating. The polyester mentioned here refers to a polyester synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative, such as polyethylene terephthalate or its copolymer, polyethylene naphthalate or its copolymer, etc. Furthermore, a blend of these polymers and a small proportion of other resins may be used.
Such polyesters contain various additives such as various ultrafine inorganic powders, colorants, ultraviolet absorbers, lubricants,
Conductive substances, flame retardants, stabilizers, etc. may be contained in amounts that do not impair the purpose of the present invention. In addition to the above-mentioned polyester film, the base material used in the present invention may include biaxially stretched nylon film,
Acetate film, OPP, polysulfone,
Even when applied to films made of polyether sulfone, aromatic polyamide, etc., certain effects can be obtained. Polyester film is the best material in which the antistatic agent can maximize its properties as a leader tape or slip sheet in relation to the surface. In order to enhance adhesion with the antistatic agent monolayer, polyester films are subjected to treatments such as corona treatment, plasma treatment, primer coating treatment, sandblasting treatment, and etching treatment, either singly or in combination.
It may be done prior to application of the coating composition, or it may be a base printed on one or both sides, for example. Further, there is no problem in including a small amount of some functional substance in the antistatic agent composition as long as this property is not significantly deteriorated. The antistatic film thus obtained can be applied to various uses, but the antistatic film of the present invention exhibits properties suitable for use as a slip sheet, especially soda tape for magnetic tape. In other words, the applied effective substance continues to function without disappearing when it comes into contact with the same surface during feeding and winding up like a leader tape, when it comes into contact with a metal fixing pin in the cassette, and even when it comes into contact with the surface of the magnetic layer. In this sense, the antistatic film of the present invention has a feature. For such applications, it is better to form a monomolecular oil film with a mixture of antistatic ability and lubricating action than to search for and modify film-forming antistatic agents using binders. Compared to the prior art, the present invention advantageously takes advantage of the combination of activators to form a surface that is far more durable under various environmental conditions than the binder-type coating agent. There are some good things about it. EXAMPLES In order to make the content of the present invention clearer, further examples will be given and explained. Example 1 and Comparative Example Consisting of olelimidazoline ethosulfate with a cationization rate of 72%, polyoxyethylene octyl phenyl ether with an HLB of 8, and sodium propionate, the ratio (active ingredients) of which is 66:
An aqueous solution containing 1.5% by weight of an antistatic agent with a ratio of 27:7 was diluted 6 times with a mixed solvent consisting of isopropanol/water = 7/3 (weight ratio).
It was roll coated onto a 36μ polyethylene tetophthalate film in an undried state at a coating weight of 6 g/m ² on one side, and dried by passing through a heat oven at 80 to 120°C for 15.6 seconds. This winding roll was aged for 42.3 hours in a clean room controlled at 60°C to transfer the antistatic agent to the non-coated surface. The surface tension of this film was measured using the JISK6768 method, and the surface tension was 54 dyne/cm at all locations.
The above values were shown. Also, vibratory capacitance type potentiometer
When surface resistance was measured using TR-84M model (manufactured by Takeda Riken), the average was 6.5 x 10゜Ω/at 20℃ x 65%RH.
It was cm. After confirming this, the coated material was rolled into a 1/2" width onto a microslit reel in a room with a cleanliness level of 100 (sample). On the other hand, for comparison, a grade 4 film-forming antistatic agent was used. Ammonium salt cation type acrylic conductive resin (Elecondo PQ-10/PQ-50=5/
5 (manufactured by Soken Kagaku Co., Ltd.) to obtain an antistatic film with a dry film thickness of 0.4 μm, and wound it onto a reel in the same manner as described above to prepare a leader tape. This film showed a surface resistance value of 1.3 x 10゜Ω/cm at 20℃ x 65% RH (sample) In addition, a leader tape was prepared as a blank film even in a completely uncoated state (sample) . The blank uncoated film is 10 ¹⁶
The resistance value was Ω/cm or more. Next, we obtained 20 volumes of commercially available VHS video tapes (normal type) with different lot numbers, disassembled them in a clean bench, made a set of 5 volumes each, and replaced the leader tape part with the prototype. I prepared a replacement. After conducting a shuttle test 100 times in an atmosphere of 40°C and 80% RH using multiple VHS video decks, the dropout (D/O) situation was measured for each. The results are shown in the table below. Note that dropout (D/O) was measured by the following method. After running the tape for 5 minutes, use a Shibasoku drop-out counter model VH01B to
O (number of pieces per minute at 15 μsec-20 dB) was measured, and this measurement was repeated five times to obtain the average value. D/O in the table indicates the ratio with respect to the number of D/O when measuring a commercially available tape as is, which is 1.

[Table] Example 2 Polyethylene terephthalate with an intrinsic viscosity of 0.62 (heat of crystal fusion 9.8 Cal/g) measured in orthochlorophenol at 35°C was extruded from a die using an extruder, and it was left to stand still on a drum cooled to 40°C. An unstretched film with a thickness of 453μ was obtained by cooling while applying an electric current, and then stretched 3.6 times in the longitudinal direction on a metal roll heated to 93°C. The ratio of olelimidazoline ethosulfate with a cationization rate of 72%, polyoxyethylene octyl phenyl ether with an HLB of 8, and sodium propionate (active ingredients) is
An aqueous solution containing 1.5% by weight of a composition of 61:30:9 was mixed with isopropanol/water = 7/3 (weight ratio).
The solution was diluted twice with a mixed solvent ^consisting of: Then immediately go through a preheating zone of 95℃ to 105℃.
The film was stretched 3.6 times at ℃ and then heat treated at 210 ℃ for 4.1 seconds to obtain a biaxially stretched film with an average thickness of 36μ. The surface resistivity value of the treated surface of this film at 20° C. x 65% RH was 3.5×10 ¹⁰ Ω, and the surface tension was 54 dyne/cm or more. Furthermore, when used as a leader tape for a VHS video tape in the same manner as in Example 1, the D/O measurement result was 0.96, which was good.

Claims (1)

[Scope of Claims] 1. A coating composition containing olelimidazoline ethosulfate, polyoxyethylene alkyl phenyl ether, and fatty acid metal salt is applied to at least one surface of a plastic film to a thickness that imparts antistatic properties. An antistatic film characterized by: 2 Oleylimidazoline ethosulfate has the following structure Here, R is _CH3 ( _CH2 ) _7CH =CH( _CH2 ) _-7 . The antistatic film according to claim 1, which is a compound having a cation content of 50 to 90%. 3. Claim 1, wherein the polyoxyethylene alkyl phenyl ether is polyoxyethylene octyl phenyl ether or polyoxyethylene nonyl phenyl ether.
Antistatic film as described in section. 4. The antistatic film according to claim 1 or 3, wherein the polyoxyethylene alkyl phenyl ether has an added mole number of 8 to 10 and an HLB of 6 to 12. 5. The antistatic film according to claim 1, wherein the fatty acid metal salt is an alkali metal salt of a fatty acid having 1 to 3 carbon atoms. 6. The antistatic film according to claim 1 or 5, wherein the fatty acid metal salt is sodium propionate. 7 Each component in the coating composition is 77 to 50% by weight of oleyl imidazoline ethosulfate and 20 to 35% by weight of polyoxyethylene alkyl phenyl ether.
and fatty acid metal salt in a proportion of 3 to 15% by weight, Claims 1 to 6
The antistatic film described in any of the above. 8. The antistatic film according to claim 1, wherein the coating composition is coated with an aqueous solution or a water-lower alcohol solution containing 0.01 to 10% by weight of the active ingredient. 9. The antistatic film according to claim 1, wherein the coating composition is applied during or after the film manufacturing process. 10 Apply the coating composition to the entire surface of the film according to JIS standards.
The surface tension value measured with K-6768 is 54dyne/cm
The antistatic film according to claim 1, characterized in that it is coated in the above ratio. 11 Claim 1 characterized in that the plastic film is a polyester film
Antistatic film as described in section. 12. The antistatic film according to claim 11, wherein the polyester film is a polyethylene terephthalate film. 13. The antistatic film according to claim 1, wherein the film is a leader tape for a magnetic tape or a film for a slip sheet.