JPS6044725B2 - Polishing roll for magnetic tape - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic tape polishing roll used in a method for polishing the surface of magnetic recording media such as video tapes, memory tapes, audio tapes, etc.

Conventionally, the following four methods have been known for polishing the surface of the magnetic layer of a magnetic recording medium.

(1) A method of improving the dispersant and dispersion method at the manufacturing stage of the magnetic coating liquid and forming a magnetic layer with less surface irregularities immediately after coating.

(2) A method of polishing the surface of the magnetic layer by applying and polishing the drying agent by rubbing the magnetic layers together at a high relative speed.

(3) A method of friction polishing with an animal hair, plastic or metal brush.

(4) A method of forming a magnetic layer using a pressure roll called a supercalender.

The above four methods had the following problems.

In method (1), electromagnetic conversion characteristics, mainly sensitivity and S/N ratio, do not reach fully satisfactory values.

Method (2) is impractical because dropout due to powder of chips generated from the magnetic layer during polishing increases.

With method (3), it is impossible to achieve the surface gloss required for high-density recording. In method (4), the material of the elastic roll is
Rolls made from raw cotton, absorbent cotton, pulp, cotton, wool, etc., such as cotton rolls, pool mat rolls, and woolen rolls, have been used, but these elastic rolls do not provide a sufficient polishing effect; There was an extremely large amount of noise (chroma noise) when recording signals.

The above problems are due to the lack of polishing effect of the magnetic layer and the large unevenness (roughness) of the surface of the magnetic layer.

The present invention uses the above-mentioned method (4) to improve the surface properties of the magnetic recording layer, thereby reducing the chroma noise of video signals and improving the S/N ratio of audio signals. The present invention provides a polishing roll.

The principle of the calender, as illustrated in Fig. 1, is to apply high linear pressure between metal rolls M1, M2, and M3 with excellent surface properties and elastic rolls E1 and E2 to pressure-form a magnetic recording material. .

Generally, this inter-roll pressure is used to polish the surface of the magnetic recording medium. In FIG. 1, A indicates a delivery roll, and B indicates a take-up roll. Further, the number of metal rolls (Ml, M2, M3, M4...) and elastic rolls (El, E2, E3...) can be increased or decreased as desired.In the conventional method, these elastic rolls are manufactured. case,
There were two methods: simply using the roll part as a core metal and casting it, and another method of machining resin into a pipe shape and hammering it into the core metal or heat-fitting it.

The polishing roll manufactured by this method had the shape shown in FIG. 2a, but it had the following problems.

(a) Because the nip pressure of the super calendar is large,
The load applied to the rolls is so large that they cannot withstand the pressure, producing a noise called roll squeal.

(b) Due to the roll's own heat generation, the central part of the roll expands in a drum shape due to thermal expansion, as shown in Figure 2b, and the pressure applied to the roll becomes uneven, resulting in uneven thickness in the manufactured magnetic tape. occurs.

(c) When the wall thickness is increased, the amount of expansion increases, and when the wall thickness is decreased, cracking or peeling occurs.

(d) Uneven temperature distribution within the roll causes uneven hardness, resulting in uneven pressure and uneven thickness in the manufactured magnetic tape. In FIG. 2, 4 is an elastic part, 2 is a metal roll core, and 3 is a thermal expansion part.

In order to eliminate the above drawbacks, the following conditions are necessary.

(1) The structure is such that thermal expansion due to self-heating of the elastic portion of the roll is absorbed in the axial direction of the roll.

Specifically, by adjusting the inner diameter of the elastic part of the roll and the outer diameter of the metal roll, it is possible to appropriately slide and expand in the axial direction, rather than being fixed to the metal roll during use. Then, the deformation of the roll due to contact with the metal roll is made uniform, and pressure is applied evenly.
(Ii) In order to prevent roll squealing, the roll should not peel off, and should not crack or break.

(Iiii) Preventing roll deformation, preventing rise in temperature at extreme parts of the roll, and preventing uneven hardness.

(Iv) Measure to improve durability.

In order to satisfy the above conditions, it is necessary to adopt the structure shown in FIG.

That is, as a result of research, it was found that the elastic roll 1 was attached to the metal roll shaft 2.
The metal roll shaft is made longer than the elastic roll. It has been confirmed that the above conditions can be satisfied by providing a polishing roll for magnetic tape in which end plates 4 are provided at two positions with a length corresponding to the amount of thermal expansion in the axial direction of the elastic roll. . This is because the inner diameter of the elastic roll is adjusted so that it can slide appropriately against the diameter of the metal roll shaft during thermal expansion, and an end plate is provided to position and fix the elastic roll. .

Further, as a result of considering the elastic roll, it is preferable that the material of the elastic roll has the following characteristics.

1. High hardness and should not break even under high linear pressure.

2. Has excellent wear resistance.

3. Low electrostatic charge and does not attract dust.

4. Excellent surface properties.

5. Not easily deformed or softened at high temperatures.

Various studies have been made in the past in order to obtain materials that satisfy these characteristics. That is, as an improvement of the conventional fibrous roll, an elastic roll using urethane comb (Japanese Patent Application Laid-open No. 104611/1983) is known. However, urethane rubber has poor mechanical strength and cannot be used under high pressure between the rolls, the rolls are easily broken during continuous use, dust is generated due to scraping of the roll surface, there are many unevenness on the surface of the magnetic layer, and during storage. There were practical problems such as easy swelling due to humidity and poor solvent resistance. In consideration of the above points, the present invention uses an elastic roll made of polyamide resin that has a shore hardness D of 70 or more and a coefficient of linear expansion of 8 x 5/℃ or more, and at the same time has sufficient compressive strength. The present invention provides a polishing roll for magnetic tape obtained by the present invention.

That is, in a magnetic tape polishing roll consisting of a metallic roll shaft and an elastic roll provided around the roll shaft, the length of the elastic roll is 60 to 250 cTn, which corresponds to the amount of thermal expansion of the elastic roll. 2 at the length position
Further, the inner diameter of the elastic roll is set to be 0.83% to 1.50% smaller than the outer diameter of the roll shaft, and the roll shaft has a diameter of 80 to 100%. Shrink fitting is performed at a heating temperature of C, and the elastic roll has a wall thickness of 3.
0 to 10-, a shore-D hardness of 70 to 1000, and a linear expansion coefficient of 8 x 1-5/°C or more,
This is a polishing roll for magnetic tape, characterized in that the polishing treatment is performed at 30 to 150°C.

As shown in FIG. 3, the polishing roll for magnetic tape of the present invention is provided with an elastic roll 1 around a metal roll shaft 2,
Furthermore, donut holes are provided at two positions of the metal roll shaft 2 at two positions with a length that is greater than the length (L) in the axial direction of the elastic roll 1 and corresponds to the amount of thermal expansion (e) of the elastic roll. This is a polishing roll for magnetic tape provided with a disc-shaped end plate 4.

The cross sections of these parts perpendicular to the roll axis are all circular. Also, as shown in FIG. 4, the outer diameters of the metal roll shafts 2 are all made the same, as shown in FIG. 5, a fixed washer 5 is provided, and as shown in FIGS. 6 and 7, the end plates 4
You may change the shape of.

Furthermore, as shown in FIG. 8, which end plate 4! Even if the mechanism is such that only one side can move in the axial direction (e) of the metal roll shaft 2, the end plate 4 can be moved freely depending on the amount of thermal expansion of the elastic roll 1. good.

Such a structure is advantageous because the end plate also moves in response to the deformation that escapes the expansion of the elastic roll in the axial direction. The polishing roll for magnetic tape of the present invention is manufactured by the following method.

The inner diameter d of the elastic roll 1 is made smaller than the outer diameter d'' of the metal roll shaft 2 by the difference in the amount of thermal expansion of the elastic roll 1, and the elastic roll 1 formed to the required dimensions is The end plate 4 is heated and shrunk-fitted onto the metallic roll shaft 2. The heating temperature is preferably about 80 to 100°C.Then, the end plate 4 is shrink-fitted onto the metallic roll shaft 2 (at about 200 to 300°C). Secure with a pull-out lock or screw.

The thickness of the donut-shaped end plate is approximately 50 to 100 mm.
? The condition is good. Furthermore, in order to make the end plate 4 movable as shown in FIG. 8, it is necessary to make the inner diameter of the end plate larger than the outer diameter of the metal roll shaft.
The difference between the inner diameter and the outer diameter may be such that the end plate is moved by the force exerted on the end plate by the expansion of the elastic roll.

The distance e between the elastic roll and the end plate 4 is the temperature at which heat is generated due to friction during polishing of the magnetic tape.
A distance corresponding to the amount of thermal expansion of about 50°C is required.

The length of the elastic roll used for polishing is approximately 20 to 250 mm.
cm, and in this case, the length of ′ is approximately 0.6 to 257 cm.
It becomes about 07n. For example, in the case of an elastic roll of 100CTn, ' is about 3 to 10T7t. Therefore, the ratio of the length of e to the length of the elastic roll is 100:0.3~10
It is necessary that the ratio is 0:1. In addition, the thickness of the elastic roll provided around the metal roll shaft is approximately 20 to 150T, taking into consideration the amount of thermal expansion, cracks, calendar effect, and loss due to polishing when the elastic roll is scratched.
IOfL, preferably 30 to 10071n. An appropriate value is selected for this depending on the length L of the elastic roll. In the present invention, the polyamide resin is a condensation polymer having an acid amide bond (-CONH-) in the main chain.
(1) Condensation of diamine and dicarboxylic acid: H2N-R1-NH2+HOOC-R2-COOH
→＋． HN-R1-NHCO-R2-CO++H2
O{2) Condensation of amino acids: H2N-R3-COOH
−＋−＋． Ring opening of HN-R3-CO'+deca(3)lactam: A-R4-CO→-+. HN-R4-CO+
"L-----1" In the above formulas (1) to (3), R
1, R2, and R4 are none or a divalent group having 1 to 20 carbon atoms; R3 represents a divalent group having 1 to 10 carbon atoms;

R1 is preferably one in which two nitrogen atoms are directly bonded without a substituent, alkylene or alkenylene having 1 to 20 carbon atoms, cyclohexane seal, phenylene, tolylene, xylylene, naphthylene, biphenylene, and the like.

R2 is preferably a compound in which two carbon atoms are directly bonded without a substituent, alkylene or alkenylene having 1 to 20 carbon atoms, cyclohexane seal, phenylene, tolylene, xylylene, naphthylene, biphenylene, and the like.
R3 is alkylene having 1 to 10 carbon atoms, or alkylene having 1 to 10 carbon atoms;
Preferred are carboxyl-substituted alkylene having 10 carbon atoms, phenyl-substituted alkylene having 1 to 10 carbon atoms, and the like. R4 has no substituent and a nitrogen atom and a carbon atom are directly bonded,
Alkylene having 1 to 20 carbon atoms is preferred. Also, (1
The dicarboxylic acid of formula ) may be anhydride, ester, etc.
2) The amino acid in formula may be anhydride.

Diamines of formula (1) include hydrazine, methylenediamine, dimethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, Hyperazine, diaminocyclohexane, di(aminomethyl)cyclohexane, bis-+. 4-aminocyclohexyl)methane, bis-(4-amino-1,
As dicarboxylic acids such as (2-methylcyclohexyl)methane, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 4,4″-diaminobiphenyl, tolylenediamine, xylylenediamine, naphthylenediamine, etc. are oxalic acid, malonic acid, succinic acid,
Glutaric acid, adipic acid, himeric acid, corkic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, hexadecanedicarboxylic acid, tapsiaic acid, Japanese acid, maleic acid, fumaric acid, Citraconic acid, diglycolic acid, malic acid, citric acid, phthalic acid, isophthalic acid, terephthalic acid, maleic anhydride, phthalic anhydride, etc. are used. Amino acid (aminocarboxylic acid) of formula (2)
Examples include α-aminoacetic acid, L-α-aminopropionic acid, L-α-aminoisovaleric acid, ε-aminocaproic acid, L-α-aminoisocaproic acid, L-α-amino-
β-phenylpropionic acid, L-aminosuccinic acid (aspartic acid), L-α-aminoglutamic acid (glutamic acid), γ-aminobutyric acid, α-amino-n-adipic acid, 11-aminoundecanoic acid, α- Amino-DL-isoamyl acetic acid, α-amino-n-monobutyric acid, 2-amino-2
-Methylbutyric acid, α-aminocapric acid, α-aminocapric acid, 1-aminocyclohexanecarboxylic acid, α-
Aminocyclohexyl acetic acid, 1-amino-α-methylcyclohexanecarboxylic acid, ethyl aminomalonate, β-
Penzyl-L-aspartate, β-benzyl-D-aspartate, γ-benzyl-DL-glutamate, and the like are used.

Lactams of formula (3) include isocyanic acid, glycine anhydride, α-pyrrolidone, α-piperidone, γ-butyrolactam, δ-valerolactam, ε-caprolactam,
α-methylcaprolactam, β-methylcaprolactam, γ-methylcaprolactam, δ-methylcaprolactam, ε-methylcaprolactam, N-methylcaprolactam, β,γ-dimethylcaprolactam, γ-ethylcaprolactam, γ-isopropylcaprolactam, ε-isopropyl Caprolactam, γ-butylcaprolactam, E-enantholactam, ω-enantholactam, η
Mono-capryllactam, ω-capryllactam, ω-laurolactam, etc. are used.

j These polyamides are commonly called nylons.

Specifically, nine-1 is produced by the polymerization of isocyanic acid, nylon-2 is produced by the polymerization of N-carboxyamino acid anhydride, nylon-3 is produced by the polymerization of β-aminopivalic acid, nylon-4 is produced by the ring-opening polymerization of α-pyrrolidone, and the opening of α-piperidone. Nylon 5 by ring polymerization, nylon 6 by ring-opening polymerization of E-caprolactam, nylon 7 by polymerization of ω-aminoenanthate, nylon 8 by ring-opening polymerization of caprylolactam, nylon 9 from ω-aminononylic acid. Nylon 1 by ring-opening polymerization of purinlactam, nylon 11 from 11-aminoundecanoic acid, nylon 12 by ring-opening polymerization of ω-laurolactam, nylon 65s by condensation polymerization of hexamethylene diamine and adipic acid, hexamethylene diamine and sebacic acid. Nylon 610 is produced by condensation polymerization. In addition, these nylon copolymers,
For example, nylon 6/66/610 (copolymerization ratio: 10/
40/50) can also be used. Furthermore, copolymers of these nylons and other monomers can also be used.

Specifically, graft copolymers with vinyl monomers such as 2-methyl-5-pinylpyridine, styrene, methyl methacrylate, sodium acrylate, vinyl acetate, vinylidene chloride, and acrylonitrile; ethylene oxide;
Ring-opening polymerizability of propylene oxide, ethyleneimine, cyclooxabutane, ε-caprolactam, ethylene sulfide, epichlorohydrin, maleic anhydride, phthalic anhydride, hexahydrophthalic anhydride, dichloromaleic anhydride, dodecylsuccinic anhydride, etc. These include copolymers with monomers. These can be made into copolymers by conventional methods such as graft polymerization, acylation, and alkylation.

In addition, monomer polymerized nylon (MOnOmer) is obtained by rapidly polymerizing lactam in the presence of a catalyst during ring-opening polymerization to form a polymer block.
CastingNylOn, MCNylOn) can also be used in the present invention. In producing the polyamide resin of the present invention, by adding a crystal nucleating agent, fine, fine, and uniform crystals can be obtained.

As a crystallizing agent, Pb3(PO4)2, NalIPO4
, Na7p5Ol6 and other phosphorus compounds; corundum, rutile, kaolin, asbestos, graphite, MOS2
, WS2, SiO2, talc, and other ore fine powders; polyethylene terephthalate; and polyethylene naphthalate and other polymer powders. Also, it may be reinforced with glass, such as glass. FRTP (Fi?RGlass Reinlx
)RcedN'111erm0P1astic)Resin is used.

Among the above polyamide resins, MC nylon is particularly preferred. A lubricant (MOS2) is added to MC nylon during polymerization.
, WS2, etc.) can also be added. The molecular weight of these polyamide resins is 10,000 to 10,000 (4)
Preferably it is 50,000 to 60,000 degrees.

The degree of polymerization is about 150 to 3 concave. Product names include Amiran CMlO3l (Toray K.K.), Ube Nylon EA
lO3O (Ube Industries K.K) Grillon AlO5O (Unitika K.K) PlaskOn82ll, 8229 (Al
ljedChemlOal. sCOrp), Spenc
erNylOn6O7 (Spencer Chemica
lCO, Ltd), FOsterNylOnBK4OF
', BK4OT(FOsterGrantCO.,Lt
d. ),)UltramidBKRll44/3 (B
ASFA. G. ), DLlrethanBK5OF',
BK64F' (Bayer A.G.), Marany
Nylon 6 such as lFl6O, Fl7O (ICILtd); Amiran CM3O2l (Toray K.K.), Zyte
I42 (E.I.DuPOntdeNemOurs&C
O. ), [Jltramid, AKRll83(BAS
F.A. G. ), MaranyIAl5OMlAlOOE
(ICILtd.), NylatrOnGS (POIy
Nylon 66 such as merCOrp; Amilan CM2
OO6 (Toray K.K) Zytel38 (E.I.DuP
OntdeNemOur-s&CO. )Ultrami
dS4, S4K (BASFA.G.), Marany
Nylon 610 such as lBlOO, BlOOC (ICILtd.); Amiran CMlOO3G (Toray K.K.),
UBE nylon IBlOl3G (Ube Industries K.K),
Grillon AlO3OGF (Unitika K.K) Plask
On823O(AlledChemicalCOrp
．． ), DurethanBKV3OH (Bayer A.
FRT nylon 6 such as UltramidB3G (BASFA.G.);
POntduNemOurs&CO. ), Nylatr
OnGS-51 (POlymerCOrp), ~ Kidney An
ylAl9O (ICILtd.), Ultramld
A3G (BASFA.G.

) etc. FRTP nylon 66: Amilan XF5OOO
．． ．． FRTP nylon 12 such as XF5OOOF (Toray K.K.); MC9Ol, MC9O4, NyratrOn
GSM (MC8Ol) (POIymerCOrp. and Mitsubishi Plastics K.K.), Monomaron 21100, 21115
,21200,21215,21300,21315(
Starlight Industries K. MC nylons such as K) are known. Regarding these polyamide resins, Osamu Fukumoto (ed.), Plastic Materials Course (16), 1. Polyamide Resins, Published by Nikkan Kogyo Shimbunsha, July 25, 1920; Murahashi, Imoto,
Edited by Tani, 1 Synthetic Polymers VJll~186 pages, June 15, 1970, Asakura Shoten Publishing; US Patent No. 2130497; 2130523: 2149273; 215806
No. 4; No. 2223493; No. 2249627: 2534
No. 347; 254035 Trowel; 271562 inches; 2756
No. 221: 293986 Trowel; No. 2994693: 301
No. 2994; No. 3133956, No. 3188228; 3
No. 193475; No. 3193483; No. 3197443; No. 322636? ;3242134;3247167
No.; 32990 No. 4; 332835? ;3354123
It is stated in the number etc.

Furthermore, polyimide resins and polyamideimide resins synthesized by a method similar to the above-mentioned polyamide resins can also be used.

Polyimide resins are produced by self-polycondensation of acid anhydrides or their esters (4-aminophthalic anhydride, dimethyl-4-diaminophthalate, etc.); by polycondensation of acid anhydrides and diamines; by acid anhydrides A soluble polyamic acid is obtained by reacting a diamine with a diamine in an organic solvent, and is obtained by a method of intramolecular dehydration.

Polyamide resin is produced by the reaction of a low molecular weight polyamide with an amino group at the end with an acid anhydride; the reaction of a low molecular weight polyamic acid with an amino group at the end with dibasic chloride; the reaction of a trimellitic acid derivative with a diamine. Obtained by reaction methods, etc.

Acid anhydrides or derivatives thereof include pyromellitic anhydride, pyromellitic acid-1,4-dimethyl ester, pyromellitic acid tetramethyl ester, pyromellitic acid ethyl ester, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3″,4,4″-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2″,3,3″-biphenyltetracarboxylic acid Anhydrides, 2,2'', 6,6''-biphenyltetracarboxylic dianhydride, etc. are used, and the diamines used are the above-mentioned aromatic diamines.

As a synthesis solvent for polyamic acid, dimethylformamide, dimethylacetamide, dimethylmethoxyacetamide, N-methylcaprolactam, dimethylsulfone,
Tetramethrene sulfone, N-acetyl-2-pyrrolidone, etc. are used.

Regarding polyimide, see M. T. BO? RtetalJO
SongNalOfAmerjcanChemicalSOcj
ety3O, p.ll4O (published in 1908), US Patent No. 2710853; No. 28676; 28802 (to)
No.;3073785;3179614;31796
3 inches; No. 3179633; No. 3179634, etc.; regarding polyamide-imide, see G. M. BowertalJ
OumalOfPOlymerScience,″A-
13135 pages (published in 1903); US Patent 24210
No. 24: British Patent No. 570858: French Patent No. 386
No. 617; described in Pelkey Patent No. 6509, etc.

The metal roll shaft and end plate in the present invention are made of metals that are used in ordinary polishing rolls. For example, cast iron (C content 2-4%), carbon steel, 5-7
%Ni cast iron, 14-17%Si cast iron, stainless steel, stainless steel cast steel, heat-resistant steel, heat-resistant cast steel, 13%Cr ferrite steel, 14-25%Ni austenitic cast iron, 18Cr
-8Ni austenitic steel, duralumin, etc.
The surface hardness of the elastic roll of the present invention is Shore hardness D (J
IS, K-6301) 70 or more, preferably 70-1
The compressive strength (AP
TM, D-695) is preferably 600 kgId or more, preferably 700k9 Nod or more. Also, the linear expansion coefficient is 8×10
-5/℃ or higher, preferably 8×10-5 to 8×10-4
It was also found that there is a good polishing effect when the temperature is /°C.
Shore hardness D is 70 or less, compressive strength is 600k91
If it is less than d, good surface properties cannot be obtained, and if it is more than 100, it becomes brittle, loses elasticity, and cannot be used for polishing because it will break. Also, if the coefficient of linear expansion is 8 x 10-5/℃ or less, the elastic roll will expand (
(see FIG. 2(b)) does not cause enough deformation to escape in the axial direction. If the temperature exceeds 8×10 −4 /° C., the deformation of the elastic roll is too large and a good polishing effect cannot be obtained.

When using the polishing roll for magnetic tape of the present invention,
The pressure between the metal roll and the elastic roll during the polishing treatment is 250 to 1000 k91d1, and the processing temperature of the metal roll during the polishing treatment is preferably 30 to 150°C, preferably 40 to 100°C.

If the pressure between the rolls is 250k9 nod or less, the polishing effect
There is no effect, and if it exceeds 1000k91cIt, there is a risk that the magnetic recording medium will be destroyed.

In addition, even if the treatment temperature is below 30℃, there is no polishing effect, and 15
If the temperature is 0° C. or higher, deformation due to softening of the magnetic layer occurs, which is not preferable. Furthermore, if there are joints or wrinkles on the surface of elastic rolls made of polyamide resin, uneven pressure will occur around them, so in order to solve this problem, elastic rolls manufactured using the casting method should be used. was found to be suitable for use and showed excellent values in terms of compressive strength.

Especially among polyamide resins, nylon 6 and nylon 6
It has also been found that particularly good effects can be obtained when MC nylon made of nylon 61 is used for the elastic roll. The effects and advantages of the present invention are shown below. Roll self-heating (When an elastic roll is pressed against a metal roll, the contact area becomes concave and the other areas become convex.

Thermal expansion occurs due to the heat generated when rotating at high speed in such a state) or the heat received from the metal roll (heat from the heater built into the metal roll), but since it can expand in the axial direction, deformation does not occur. It does not accumulate and does not cause bulges in the outer diameter of the roll. As a result, the pressure of the rolls was applied uniformly, and there were no problems such as uneven surface properties of the tape and severe uneven pressure causing the magnetic tape to break. (B) The phenomenon of roll squeal and cracking became zero, and the life of the roll became about 3 to 5 times longer. (C) The roll itself has improved durability against heat, etc., so the nip pressure of the roll (30-500k91cm) has been reduced from 300k9 to 300k91cm.
The one that could only get less than 1cm was 500k91cm, and if a certain type of resin was used, it would be 600-700k91cm.
This enables high nip pressure of the magnetic tape, improves the filling degree of the magnetic tape and improves the surface appearance, reducing chroma noise, S/
Significant improvements in N and reduction in envelope variation were observed in precision tapes, video tapes, and small video tapes.

(D) Continuous operation at high nip pressure for long periods of time is possible,
The calendar is now up and running.

By using the polishing roll of the present invention, it is possible to improve the surface properties of the magnetic recording layer, and as a result, it is possible to reduce the chroma noise of the video signal and the S/N ratio of the audio signal, etc. The characteristics become better when the envelope fluctuation rate decreases.

As for the video output waveform, as shown in FIG. 9 (ideal output waveform), if the input level during recording is constant, it is desirable that the maximum level of the reproduction output is always constant.

However, the actual output may vary due to uneven contact between the magnetic head and the magnetic tape and other causes, as shown in Figure 10 (actual output waveform).
It fluctuates as shown in . There is no particular method to express this fluctuation in output level, but in order to quantitatively evaluate this fluctuation in the present invention, we calculate the ratio of the output fluctuation range to the highest output level, and calculate the envelope fluctuation rate. I decided to express it as In the present invention, this envelope was evaluated using the following general formula (1).

? ×100=Envelope fluctuation rate (%) (1) Vs
: Width of 1/2 of the output P-P value of the carrier signal VO: Width of output fluctuation of the carrier signal According to this evaluation method, the value is 15% or more at the conventional technology level, but the polishing of the present invention When a roll is used, this value is 13% or less, which is very preferable.

When a magnetic tape is polished using the magnetic tape polishing roll of the present invention, the following advantages are found.

(1) Color noise can be reduced, that is, envelope fluctuation rate can be reduced. (Ii) Increased video sensitivity is possible.

{111) Roll breakage during continuous use is superior to rubber and fibrous rolls.

(Iv) Can be used with high inter-roll pressure.

() There is almost no hardness unevenness within the roll, so the polishing effect is good. (Vi) No friction occurs due to scraping of the roll surface.

(Transfer) It is possible to reduce unevenness on the surface of the magnetic layer. (
VIll) By absorbing moisture, the surface electrical resistance of the coal can be lowered, and charging can be prevented.

'' (Ix) By machining the roll surface, it is possible to create a roll with a surface that can be used immediately. (X
) During storage, it will not swell due to humidity and become defective.

(Xi) Excellent solvent resistance compared to rubber-based materials,
Easy to clean.

(Xii) In the case of the same envelope fluctuation rate, it is possible to reduce the number of calendar stages.

(Xij) Carbon black and glass in elastic roll
It is possible to carry out antistatic treatment by mixing a lubricant such as fluorite, carbon black graphite polymer, tungsten disulfide, or a surfactant.

The present invention will be explained in more detail below using examples.

Those skilled in the art will readily understand that the components, proportions, order of operations, etc. shown herein may be modified without departing from the spirit of the invention. Therefore, the invention should not be limited to the examples below.

Example 1 (Manufacture of magnetic tape) Maghemite (γ-Fe2O3) 3(1) parts vinyl chloride vinyl acetate copolymer (copolymerization ratio 87:13W
t. %, molecular weight approx. 400) Shunbu epoxy resin (reactant of biphenol A and epichlorohydrin, hydroxyl group content 0.1, molecular weight approx. 470. Epoxy content 0.36-0.4.4N specific gravity (20℃) 1.1181 ) 3? Silicone oil, (dimethylpolysiloxane 5 parts) toluenesulfonic acid ethylamide 7 parts ethyl acetate
25 liters of methyl ethyl ketone
Place the above composition in a Pall mill, mix and disperse, and add a polyisocyanate compound (DesmOdurL-
7\Bayer. ．． A. G. A 75 Wt.% ethyl acetate solution of an adduct of 3 mol of tolylene diisocyanate and 1 mol of trimethylolpropane was added to the mixture, and the mixture was uniformly mixed and dispersed to obtain a magnetic paint.

This magnetic paint has a thickness of 20μm and a width of 600Tf0! L's Polie. Dry thickness of 7μ on tylene terephthalate film
It was applied so that it became m. Magnetic field orientation was performed using a DC magnetic field of 10,000 e, and heat treatment was performed for 80' Cll to accelerate hardening of the binder, thereby obtaining a wide magnetic tape.

(Manufacture of polishing rolls) Length 1100 TWL1 diameter 180 as a metal roll shaft
A roll shaft made of TfrfL carbon steel was used.

Various elastic rolls (see Table 1 for materials) with a length of 600mm? ,
Outer diameter 300Tfn1 inner diameter 178.5? The end plate and the elastic roll were made into a cylindrical shape with a gap of 4.0Tf0fL, and the elastic roll was heated to 100° C. and fixed by driving and shrink-fitting onto the roll shaft. This is the comparison roll. The above comparison roll has an outer diameter of 280 mm.
wn1 inner diameter 179.5? A donut-shaped end plate made of carbon steel with a thickness of 5'' was heated to 25° C. and shrink-fitted and fixed in the same manner as the elastic roll described above to produce a polishing roll of the present invention.

The thickness of the produced polishing roll is 60TWL. Using the two types of polishing rolls thus obtained, the magnetic tapes described above were subjected to polishing under the conditions of linear pressure and temperature shown in Table 1 below. The polished wide magnetic tape was slit into 3/41 nch (approximately 19 TIrIn), inserted into a U-Matic (8S0NYC0rp) video cassette, and then inserted into a video cassette recorder (CR-60).
0B type, Japan Victor K. K. 5MHz using
The video signal was recorded and re-tested.

The difference (DB) in biosensitivity between the running direction of the magnetic tape and the width direction perpendicular thereto is shown in Table 1 below. In addition, linear pressure (K9l
c7n) is pressure (KgIclt)/length of elastic roll (
α). From the results in Table 1 above, the polishing roll for magnetic tape of the present invention shows a
It was found that the difference in MHz video sensitivity was small and uniform, whereas the difference in 5MHz video sensitivity increased and was found to be non-uniform for the conventionally implanted roll of the comparative sample. From this, it was confirmed that although the polishing effect of the present invention is good, the conventional roll has uneven polishing and deteriorates the surface properties of the magnetic tape. Example 2 J- (Production of polished roll) An elastic roll (made of MC nylon) was produced in the same manner as in Example 1.
The thickness of the polishing rolls was varied to produce polishing rolls having the dimensions shown in Table 2 below.

However, the end plates were not shrink-fitted, but the metal roll shaft was provided with male threads, and the end plates were provided with female threads, and fixed with screws. In Table 2, the inner diameter of the elastic roll is determined from the inner diameter of the metal roll shaft for sample No. 1.50% for lO, ll, sample NO. 0.83% for l2 and l3, and further sample No. At l4 and l5, the value is 0.58% smaller. Using the above polishing rolls (Nos. 10 to 15), magnetic tapes were subjected to the same polishing treatment as in the example.
The properties of each polishing roll are shown in Table 3 below. From the above results, the following facts were revealed.

If the openings e on the left and right end faces of the roll are not removed, the roll will expand into a drum-like shape and become unusable because there will be no stubs in case of thermal expansion.

If the wall thickness of the roll is 100 rT1 nm or more, increasing the speed will cause self-heating of the roll, and the amount of expansion due to the generated heat and the heat received from the metal roll will increase.
I can't speed up.

If too much calender pressure is applied, high self-heating will occur,
Since the amount of thermal expansion becomes large, the calender pressure cannot be increased. Also, if it is too thin, there will be no cracks or scratches when re-polishing, which is a problem. Therefore, in order to be able to apply speed and pressure and re-polish many times, the roll length must be between 300 and 15 mm.
In the case of 00mIm, apply 3 to 10WrI on both ends of the roll!
It was confirmed that it is appropriate to leave L open and the thickness of the roll to be 30 to 100 wn. Furthermore, as a result of other experiments, when using polyamide resin, etc., the gap between the end plate part of the roll and the roll should be symmetrically set to 3 to 10 mm.
It was confirmed that it is also preferable to leave a gap of 1 m and leave the ends free in the left and right direction without any pressure, and to set the wall thickness of the roll to 30 to 100 n11 m, and to adopt a numerical value within this range according to the surface length of the roll.

Example 4 (Manufacture of polished roll) The roll hardness (Hs
D) was changed to produce a polished roll.

The resulting polishing roll was heated to a set temperature of 60°C and a linear pressure of 200°C.
Table 4 shows the state of the roll after running for about 2 hours under the test conditions of k91Cm1 calender speed 60 mImin. As is clear from Table 4, it was found that the surface condition was significantly better only when there was a certain relationship between the roll thickness and the roll hardness.

[Brief explanation of the drawing]

FIG. 1 shows an example of the polishing method of the present invention,
A is a delivery roll, B is a take-up roll, Ml, M2
, and M3 are metal rolls, and E1 and E2 are elastic rolls.

Claims (1)

[Claims] 1. A magnetic tape polishing roll comprising a metallic roll shaft and an elastic roll provided around the roll shaft, wherein the elastic roll has a length of 60 to 250 cm,
Two end plates are provided at positions with a length corresponding to the amount of thermal expansion of the elastic roll, and the inner diameter of the elastic roll is set to be 0.83% to 1.50% smaller than the outer diameter of the roll shaft. Shrink fitting is performed on the roll shaft at a heating temperature of 80 to 100°C, and the elastic roll has a wall thickness of 30 to 10
0mm, Shore D hardness is 70° to 100°, linear expansion coefficient is 8 x 10_-^5 to 8 x 10^-^4/℃, and polishing treatment is performed at 30 to 150℃. Features: Polishing roll for magnetic tape.