JPH0366084A - Slip sheet for cassette - Google Patents

Abstract

PURPOSE:To improve slipping property, traveling stability and antistatic property of a slip sheet by applying an ionic antistatic agent having a polymer structure on the back surface of a polyester film the front surface of which is covered with a silicon oxide film. CONSTITUTION:The slip layer is formed on one side of the polyester film. The slip layer essentially consists of a silicon oxide film produced by adding carboxy-modified dimethylpolysiloxane by 1 - 40 wt.% to silylpolyisocyanate compd. of silicon-reactive type, and effecting hydrolysis. The other side of the polyester film is covered with an ionic antistatic agent having a polymer structure. The silicon-reactive type silylpolyisocyanate compd. is preferably selected from compds. expressed by RnSi(NCO)4-n or (RO)nSi(NCO)4-n (wherein R is an alkyl, alkenyl or aryl group of 1 - 6 carbon number and n is 0 or 1) or condensates of these. The carboxy content in the carboxy-modified dimethylpolysiloxane is preferably 0.5 - 5 wt.%.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a slip sheet for cassettes, and more specifically, it is incorporated into tape cassettes such as audio cassettes and video cassettes, and is used to bring tape into sliding contact and prevent its loosening. This invention relates to a slip sheet for smooth running.

<Prior Art> A magnetic tape cassette is provided with a slip sheet between the tape and the cassette case in order to make the magnetic tape run smoothly. This slip sheet allows the magnetic tape to run smoothly and prevents irregular winding by rotating the wound tape with its side surface in contact with the sheet.

Traditionally, tetrafluoroethylene sheets have been used as slip sheets because of their low coefficient of friction and high thermal stability, but these sheets are expensive and have a weak stiffness due to their high flexibility. It has the disadvantage that the periphery may be bent.

In addition, a sheet of plastic film filled with or coated with conductive lubricant particles such as graphite or carbon, or paper mixed with carbon black, phosphorous graphite, molybdenum disulfide, etc., and silicone resin or fluororesin applied to the surface. There are coated sheets, etc., but these slip sheets are black and opaque, and are hidden by display paper pasted on the outside of the case, and the disadvantage is that the winding state of the magnetic tape inside the cassette cannot be seen. .

In order to improve this drawback, a method has been proposed in which silicone oil is applied to the surface of a transparent plastic sheet (Japanese Patent Laid-Open No. 146066/1983).

However, simply applying a lubricant such as silicone oil to the surface of the plastic sheet does not provide sufficient adhesion to the transparent plastic film, and when actually used, friction increases over time, resulting in a lack of durability. There is a problem that occurs.

Furthermore, a method has been proposed in which a laminate is formed by coating the surface of a transparent plastic sheet with a paint made by adding a lubricant to a thermoplastic resin such as vinyl chloride-vinyl acetate copolymer, polyurethane resin, etc. Publication No. 58-60474). However, these laminated coatings lack surface hardness,
As the magnetic tape runs, a problem arises in which scratches occur at the edges of the tape and reduce the transparency of the slip sheet.

Additionally, if the surface of the plastic sheet is covered only with silicone lubricant, the plastic sheet will become electrically charged, which will cause handling problems during the production process.Furthermore, when the magnetic tape runs, static electricity will be generated due to the friction between the tape edge and the sheet surface. , the sheet is charged with electricity, which interferes with the smooth running of the magnetic tape.

Based on these facts, the characteristics required of the slip sheet incorporated into audio cassettes are that the surface has good slipperiness, as well as excellent durability, scratch resistance, and antistatic performance. When printing is applied to the surface, the lubricant used on the surface should be transferred to the back surface so that it does not interfere with the printing.

<Object of the Invention> An object of the present invention is to provide a slip sheet for a cassette that has improved slipperiness and excellent running stability, and also satisfies antistatic performance.

<Configuration/Effects of the Invention> According to the present invention, the object of the present invention is to basically include a silicon-reactive silyl polyisocyanate compound (A) on one side of a polyester film and a silyl polyisocyanate compound (A) of 1. An ionic antistatic agent having a slip layer mainly consisting of a silicon oxide film formed by addition and hydrolysis reaction with ~40% by weight of carboxy-modified dimethylpolysiloxane (B), and having a high molecular weight polymer structure on the other surface. This is achieved by a slip sheet for cassettes, which is characterized in that it is provided with layers.

In the present invention, polyester is a linear saturated polyester synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative. Specific examples of polyester include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly(l,4-cyclohexylene dimethylene terephthalate), polyethylene-2,6-
Examples include naphthalene dicarboxylate, and also include copolymers thereof or blends of these with small proportions of other resins.

Such polyesters may contain fine particles that impart slipperiness to the film, such as additive particles such as calcium carbonate, kaolin, silica, titanium oxide, silicone resin, crosslinked styrene, etc., and precipitated particles formed from catalyst residues used in the reaction. It can also contain an antistatic agent such as sodium dodecylsulfonate. Moreover, other additives can be contained as necessary.

The polyester film in the present invention can be produced by a conventional method using the above-mentioned polyester.

This polyester film has a thickness of 25 to 100 μm
The transparency is preferably 10% or less in terms of haze.

In the present invention, the slip layer provided on one side of the polyester film is composed of a silicon-reactive silyl polyisocyanate compound (A) and a carboxy-modified dimethyl polysiloxane (
B). The silicon-reactive silyl polyisocyanate compound (A) has a silyl isocyanate bond that exhibits structural isomer resonance with the siloxynitrile,
The carboxy group of carboxy-modified dimethylpolysiloxane (B) reacts with active hydrogen to form an addition reactant, and also causes a hydrolysis reaction with moisture in the solvent, moisture in the air, etc. to form a three-dimensional crosslinked structure of silicon oxide. do.

The above addition reaction and hydrolysis reaction are thought to proceed as shown in the following equation.

(1) Addition reaction with carboxy group active hydrogen (11) Formation of silicon oxide film (hydrolysis reaction) -5i-
0-+H20+ CO2+NH3 <Silicon oxide film> By the above reaction, a silicon oxide film to which dimethylpolysiloxane is bonded via carboxyl groups is formed on the polyester film.

This reaction (hydrolysis reaction) is advantageous in that it proceeds satisfactorily at a temperature ranging from room temperature to 120° C. or lower, and that reaction by-products are gaseous and there is no reaction residue.

The silicon-reactive silyl polyisocyanate compound (A) in the present invention has a number of isocyanate groups (NGO) in the molecule in order to improve adhesion to the polyester film and to contain a large number of hydroxyl groups in the silicon oxide film. The higher the number, the more preferable, and examples thereof include R, Si(NCO)a-, (RO)-St(NGO)4-fi, and condensates thereof, which are composed of silyl triisocyanate and silyl tetraisocyanate. Here, R in the above formula is alkyl having 1 to 6 carbon atoms, aryl,
It is alkenyl, and n is 0 or 1. More specific compounds include, for example, methylsilyltriisocyanate, vinylsilyltriisocyanate, phenyldylyltriisocyanate, tetraisocyanatesilane,
Examples include ethoxysilane triisocyanate, propoxysilane triisocyanate, butoxysilane triisocyanate, and the like. These silicon-reactive silyl polyisocyanate compounds include, for example, ethyl acetate, isopropyl acetate, n-propyl acetate, isobutyl acetate,
It can be dissolved in an inert organic solvent such as n-butyl acetate, amyl acetate, ethyl lactate, n-hexane, n-hebutane, toluene, xylene, and cyclohexane to prepare a coating solution. Here, “inert” means ethanol,
Alcohols such as isopropanol, n-butanol, 2-butanol, and ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc., react with silyl isocyanate to cause cleavage of the 5i-N bond, thus causing a silicon reaction. This means that the original reactivity of the type silyl isocyanate compound will not be lowered, and undesirable phenomena such as lowered adhesion to the polyester film of the base material will not occur. Therefore, alcohols and ketones are not included in the above solvents.

Silyl monoisocyanate compounds such as trimethylsilyl isocyanate and triethylsilyl isocyanate, which have a similar structure to silicon-reactive silyl polyisocyanate compounds, form a silicon oxide structure by hydrolysis, but do not form a three-dimensional structure and contain free hydroxyl groups. Since the amount is small, the strength and antistatic properties of the coating film are insufficient, making it impossible to achieve the object of the present invention. Furthermore, silicon oxide films formed by hydrolysis of silyl diisocyanate compounds such as dimethylsilyl diisocyanate and diethylsilyl diisocyanate have a small amount of free hydroxyl groups, and cannot provide the antistatic properties required by the present invention.

Next, in the present invention, the carboxy-modified dimethylpolysiloxane (B) to be chemically bonded to the silicon oxide film has a structure represented by the following formula, and has a carboxyl group content of 0.5
~5% by weight is preferred. Furthermore, it is preferable that the carboxy group equivalent is between 500 and 4000 g/mol. If the content of carboxyl groups is less than 0.5% by weight, the reactivity with the silyl polyisocyanate compound (A) will decrease, and the amount of free siloxane that does not bond with the silicon oxide film will increase, which is not preferable. Moreover, if the content of carboxyl groups is more than 5% by weight, the dimethylsilane component will decrease and the lubricity required for the cassette slip sheet will deteriorate, which is not preferable. Specific examples of carboxy-modified dimethylpolysiloxane include "#778" manufactured by Dow Chemical Co., and 'X-62-' manufactured by Shin-Etsu Silicone Co., Ltd.
163C", "5F-8418" manufactured by Toshi Silicone Co., Ltd.
etc. can be mentioned.

Modified dimethylpolysiloxanes other than carboxy-modified include epoxy-modified, polyether-modified, amino-modified, or alkyl-modified products, but these are silicon-reactive silyl polyisocyanate compounds (
This results in unfavorable results such as poor stability of the coating liquid when mixed with A) and polysiloxane being liberated on the surface of the silicon oxide film.

Next, silicon-reactive silyl polyisocyanate compound (
The ratio of the active ingredient of the carboxy-modified dimethylpolysiloxane to Al is 1 to 40% by weight. This ratio is 1
If the amount is less than % by weight, the lubricity required for a cassette slipsheet on the surface of the slipsheet will be insufficient, and when it is incorporated into an audio tape cassette and used in an actual machine, an undesirable problem will occur in which the running will stop. If this proportion exceeds 40% by weight, the content of hydroxyl groups generated by hydrolysis of the silyl polyisocyanate compound (A>) will be insufficient, and the specific resistance of the surface of the cassette slip sheet will be 10%.
13Ω or more, and when it is incorporated into an audio tape cassette and used in an actual machine, the undesirable result is that charging during use aggravates fluctuations in the tape output (wow and flutter characteristics).

In the present invention, it is thought that free hydroxyl groups generated by hydrolysis of the silicon-reactive silyl polyisocyanate compound (A) are ionically dissociated, exhibit electrical conductivity, and impart v1 ability to prevent charging. , an antistatic agent may be contained for the purpose of imparting more effective antistatic ability. The antistatic agent may be an anionic, cationic, nonionic, or amphoteric surfactant type, or an ionic polymer conductive agent.

Such an antistatic agent may be added to the coating liquid.

The amount of the antistatic agent is preferably 1.0 to 15.0% by weight based on the silyl polyisocyanate compound (A), and thereby the antistatic properties of the cassette slip sheet can be greatly improved.

The method of forming a slip layer consisting of a silicon oxide film on the surface (one side) of a polyester film is the same as the conventional coating method of general coating agents, such as roll coating method, gravure coating method, reverse roll coating method, Mayer bar coating method, etc. This can be carried out by applying a coating liquid of about 0.2 to 3 g/- of the solid active ingredient using a coating method such as a method, a microgravure method, a comma coating method, etc., and drying it.

During the process of punching out the shape of a slip sheet for cassettes from a roll of raw material, static electricity is normally generated, resulting in frequent punching errors, problems such as adhesion of punched scraps to the sheet, and problems when assembling it into the case. Occasionally, trouble occurs where several types are operated at the same time. As countermeasures against this problem, it is necessary to prevent static electricity on the sheet surface and to prevent physical and chemical adhesion between the sheet surfaces, which is called denestability. In the present invention, the above-mentioned trouble can be avoided by applying an ionic antistatic agent having a polymer structure to the opposite side of the polyester film on which the silicon oxide film is formed.

Ionic antistatic agents having a polymer structure include acrylic, styrene, polyester, vinyl-vinylidene, and phenol polymers, quaternary ammonium salts, sulfonic acid esters, phosphoric esters, etc.
Those modified with ethylene oxide adducts etc. can be preferably used. For example, "Ol
igo-Z” 11 bottles Gosef Eye, A-46Q, C-670 manufactured by Gosei Kagaku Kogyo Co., Ltd., “Kaya Polymer” EC-003, EC-004 manufactured by Nippon Kayaku Co., Ltd., “Nirekondo” manufactured by Souken Kagaku Co., Ltd. “PQ-10, PQ-10W, PQ
-A, PQ-50B, PQ-149, and the like.

The ionic antistatic agent having such a polymer structure can be applied using a method similar to the method for forming a silicon oxide film on the surface of a polyester film, such as roll coating, gravure coating, and reverse roll coating. Coating methods such as , Meyer bar method, microgravure method, and comma coating method are used, and the coating amount is 0.03 to 2 g/rr in terms of solid content.
? is preferred.

Furthermore, other additives such as fillers, pigments, adhesion promoters, lubricants, antiblocking agents, surfactants, coating agents, fragrances, etc. can be added to the extent that the effects of the present invention are not lost.

The slip sheet for cassettes of the present invention is usually produced by embossing a coated roll film using an embossing roll, punching it into a shape of a predetermined size, and placing the slip layer surface in contact with the magnetic tape between the cassette case and the magnetic tape. Interpose and use.

The slip sheet for cassettes of the present invention has a silicon oxide film surface with excellent lubricity and excellent slip properties, and the dimethylpolysiloxane component is chemically bonded to the silicon oxide film. It is difficult to fall off or metastasize, and there is no need to worry about the silicone component bleeding out.
Excellent durability. In addition, the surface resistivity of the slip surface and the opposite surface is as low as 109 to 1012 Ω/hole, which prevents the generation of static electricity, and by coating the opposite surface with an antistatic agent having a polymer structure, the punching speed of the slip sheet can be increased to 200Ω. It can be used to record more than 1 magnetic tape per minute without causing any trouble.
The tape can run smoothly even after long-term use of over 1,000 hours.

The slipsheet for cassettes of the present invention has superior workability compared to conventional slipsheets, improves the productivity of assembling into cassettes, and also allows magnetic tapes incorporated into cassettes to be used for long periods of time. Even when the magnetic tape is used, it exhibits various excellent effects such as almost no problems such as dust adhesion to the magnetic tape or winding blur. The slip sheet for cassettes of the present invention can be used not only for audio cassette tapes, but also for smoothing and stabilizing the running of video tapes, etc., as required in DAT cassettes.

Of course, the slip sheet of the present invention is not limited to these uses, but the slip sheet of the present invention can be used in a wide range of uses.

<Example> The present invention will be further explained below with reference to Examples.

Note that parts in the examples mean parts by weight. Moreover, each characteristic was determined by the following method.

(1) Total light transmittance, haze In accordance with JIS K6782, haze is a comparison of total light transmittance (%) and scattered light transmittance (%) measured with a haze meter (manufactured by Nihon Denki Co., Ltd.) in percentage. Ta.

(2) Coefficient of Dynamic Friction Based on ASTM D1894, the coefficient of kinetic friction between the easy-sliding surfaces of the film and between the easy-sliding surface and the back surface (antistatic agent coated surface) is shown.

(3) Surface specific resistance The surface specific resistance was measured using a super insulation resistance meter (Yokogawa Electric Corporation RM-21A) based on ASTM D-257.

(4) Charge decay half-life Shishido Electric Static Honest Meter 'I'ype
The sample was fixed on the rotating disk of S-5109, and the
After rotating at RP and applying a voltage of 5 KV for 30 seconds, changes in charging voltage were examined. The time required for the voltage to reach 1/2 of the saturation voltage was determined as the charge decay half-life. Measured at 23℃, 56%R
I went in the atmosphere of H.

(5) Punching processability: 200 pieces per die of audio slip sheet.
5000 slip sheets were punched out continuously at a speed of 1 minute. The slipsheets being punched were continuously ejected from the punching machine using compressed air and stacked on trays. Shape defects of the punched slip sheets, adhesion of punching residue, and adhesion of the stacked punched slip sheets were evaluated based on the following criteria.

(6) Punch out the running stability slip sheet for audio cassettes and assemble the sheet into the C-90 cassette. This cassette was subjected to a running durability test using an audio cassette deck.

The actual running was an endurance test that repeated playback running and fast forwarding and rewinding, and the magnetic tape playback running speed was 94.
cm/sec, fast forward/rewind speed is 400cm
/see. 1 playback run and 1 rewind
The vehicle was run repeatedly for 100 cycles, and running stability was evaluated in the next test.

(il) Changes in the load applied to the motor at the initial stage of winding load and during winding after 100 cycles were investigated.

(iii) Scrapability After completing 100 cycles, the slip sheet was visually observed, and the occurrence of scratches caused by the end surface of the magnetic tape was examined according to the following criteria.

No scratches △: Partial scratches ×: Scratches on the entire surface (7) Driving durability slip sheet was punched out for audio cassettes, C-
Incorporate into 90 cassettes. Play this audio tape on a commercially available portable audio player (AIWA H3-G3).
41, replay running and fast forward/rewind were repeated for 1000 hours continuously in an environment of 0°C, room temperature, 60°C x 80% RH, and the running conditions were examined according to the following criteria.

0: Stable continuous running for 1000 hours.

Δ: After running for 1000 hours, a delay occurred in the tape feeding speed. ×: Running stopped midway.

Example 1 92.5 parts of tetraisocyanate silane, carboxy-modified dimethylpolysiloxane (Toshi Silicone ■"5F-
8418''> was mixed and diluted with n-hexane to give a solid content concentration of 2.4% to prepare a slip coating solution.

This coating solution was applied to one side of a 50 μm thick polyester film (Teijin ■ "Tijin Tetron Film" S type) using a 175 mesh gravure coater, and then dried. The coating amount after drying was about 0.15 g/-.

Next, an antistatic paint was prepared by adding 490 parts of isopropyl alcohol to 10 parts of an acrylic-modified conductive polymer (Soken Kagaku Nirekonte PQ-10).This paint was coated with a 175-mesh gravure coater for slip coating. The solution was applied to the opposite side of the polyester film and dried.The coating amount after drying was about 0.07 g/-.

Table 1 shows the results of performance evaluation of this film.

From the results in Table 1, slip properties, antistatic properties, durability,
It can be seen that it has excellent processability and has good running performance and playback characteristics as a slip sheet for audio cassettes.

Example 2 55 parts of tetraisocyanate silane, 20 parts of methyltriisocyanate silane, carboxy-modified dimethylpolysiloxane (Shin-Etsu Silicone X-62-163C)
25 parts and antistatic agent (Boron International ■“
A slip coating solution was prepared by diluting and mixing 5 parts of HIPHOLON SC'' with 1,350 parts of n-hexane and 1,350 parts of toluene.

This coating liquid was applied to a polyester film in the same manner as in Example 1, and then dried.

The coating amount after drying was about 1 g/rrr.

Next, cationic conductive polymer (Nittobo ■ “PAS”)
An antistatic paint was prepared by adding 490 parts of methyl ethyl ketone/isopropyl alcohol (1/1) to 10 parts.

This coating material was applied to the opposite side of the polyester film coated with the slip coating solution in the same manner as in Example 1, and dried. The coating amount after drying was about 0.05 g/-.

The results of this film performance evaluation are shown in Table-1.

From the results in Table 1, it can be seen that it has excellent performance as a slip sheet for cassettes.

Example 3 In the formulation of Example 1, n-hexane/toluene (4/
1) was diluted with the mixed solvent to prepare a slip coating solution.

This coating solution was applied to one side of a 50 μm thick polyester film (Teijin ■ "Tijin Tetron Film" GS type) using a 175 mesh gravure coater in the same manner as in Example 1, and then dried. The coating weight after drying was 0.4 g/-. The antistatic layer of Example 2 was provided on the opposite side of this film.

Table 1 shows the results of evaluating the performance as a slip sheet for cassettes. From the results in Table 1, it can be seen that the slip surface has excellent antistatic properties and the audio tape has excellent running performance and is suitable for being incorporated into a cassette.

Example 4 A slip coating solution was formulated in the same manner as in Example 1 by adding 90 parts of tetraisocyanate silane and 10 parts of carboxy-modified dimethylpolysiloxane (Dow Chemical #778) to a solid content concentration of 4%. This was prepared with n-hexane and applied to one side of a 50μ thick polyester film (Teijin Patidine Tetron Film Type S) using a 150-mesh microbravia coater, followed by drying. Application amount is 0.45g/r
r? Met.

Next, the formulation of the antistatic layer on the opposite side was prepared using quaternary ammonium salt-modified acrylate (Souken Kagaku "Nileconte" PQ-50).
An antistatic paint was prepared by adding 400 parts of isopropyl alcohol and 90 parts of butanol to 9.5 parts of B> and 5 parts of a fluorine-modified surfactant (Dainippon Ink Chemical Co., Ltd. "MEGAFAC" F-18310).This paint was coated and dried in the same manner as in Example 1. The coated amount after drying was about 0.08 g/+d.

Table 1 shows the results of performance evaluation of this film.

From the results in Table 1, it can be seen that the slip sheet for cassettes exhibits excellent punching workability and running stability for audio cassettes.

Comparative Example 1 In Example 1, instead of the ionic antistatic layer having a polymer structure on the opposite side of the slip layer, an antistatic agent having a surfactant-type low molecular structure (Ciastat 264A, Jordan Chemical Co., Ltd.) was used. was applied and the performance of this film was evaluated in the same manner.

The results are shown in Table-1. As the results in Table 1 show,
The low molecular weight antistatic agent was transferred from the back side to the slip surface, and although the antistatic properties were improved, the running performance of the magnetic tape became unstable, making it impossible to run, especially when running for long periods of time or in high humidity environments. .

Comparative Example 2 A cassette slip sheet was prepared in the same manner as in Example 4 except that the formulation of the slip coating solution was changed to 50 parts of tetraisocyanate silane and 50 parts of carboxy-modified dimethylpolysiloxane (Dow Chemical #778).

The results of evaluating this sheet are shown in Table 1. Free dimethylpolysiloxane migrates to the slip surface and is transferred to the back surface, impairing the punching processability of the slip sheet and the running stability of the audio tape. This was the result.

Comparative Example 3 In Example 1, a cassette slip sheet was created without providing an antistatic layer on the opposite side of the slip layer. The evaluation results of this sheet are shown in Table 1, and the punching workability and running durability were poor.

Claims (1)

[Claims] 1. A silicon-reactive silyl polyisocyanate compound (A) and a carboxy-modified dimethylpolysiloxane (B) in an amount of 1 to 40% by weight based on the silyl polyisocyanate compound (A) on one side of the polyester film. 1. A slip sheet for a cassette, comprising a slip layer mainly consisting of a silicon oxide film formed by addition and hydrolysis reactions, and an ionic antistatic agent layer having a polymer structure on the other side. 2. Silicon-reactive silyl polyisocyanate compound (A
) is R_nSi(NCO)_4_-_n, (RO)_
nSi(NCO)_4_-_n (here, R is the number of carbon atoms
-6 alkyl, alkenyl, aryl, n is 0
The slip sheet for a cassette according to claim 1, which is at least one selected from the group consisting of 1) and a condensate thereof. 3. The slip sheet for cassettes according to claim 1, wherein the carboxy-modified dimethylpolysiloxane (B) has a carboxy content of 0.5 to 5% by weight.