JP3067039B2 - Manufacturing method of polishing tape - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polishing tape suitable for finish polishing of precision electronic parts and precision machine parts, for example, magnetic disks and magnetic heads, and precision surface finish polishing of dies.

[0002]

2. Description of the Related Art A polishing layer of a conventional polishing tape is formed by dispersing a polishing resin made of an inorganic powder and a thermoplastic resin, a thermosetting resin, or a reactive resin as a binder in a solvent. A general one is formed by applying a coating liquid for forming a polishing layer on a substrate, and then performing a post-treatment according to the type of resin in the coating liquid.

[0003] Abrasive tapes using a polyester resin having a molecular weight of about 20,000 and crosslinked with a trifunctional isocyanate have been frequently used as a binder.

When such a binder is used, the reaction rate with an isocyanate is slow due to the low concentration of OH groups in the polyester resin, for example, at 70 ° C. for 36 hours or 5 hours.
0 require high have reaction temperature will trough about 80 hours at ° C.. In addition, when it is cured at such a high temperature in the state of being wound into a roll, it can be used as an abrasive tape for cutting, finishing, etc. due to variations in internal pressure and temperature distribution due to tension and the like when winding into a roll. However, there is a defect that the quality of the product changes and the product quality varies. Further, the polishing tape manufactured in this manner has a problem that the crosslink density of the binder is low and the quality changes due to the internal pressure of the roll even during storage of the product in a rolled state.

In order to solve such a drawback, the present inventor has proposed a polishing tape characterized by being cured at room temperature using a combination of a high molecular weight epoxy resin, a urethane resin and a polyfunctional isocyanate as a binder component. By providing a manufacturing method, a result which occurs during curing and which is almost satisfactory in improving the variation in the quality of the polishing tape such as machinability and finishability was obtained.

However, it is necessary to finish the surface of precision electronic parts and precision machine parts to a surface roughness of a micron or sub-micron unit. For example, in the polishing step of a thin-film magnetic disk or the like, particularly fine finish roughness is required. However, it was not possible to say that the variation in the quality of the polishing tape such as machinability and finishability was sufficiently solved.

The inventor of the present invention has conducted intensive studies on binders in order to reduce the occurrence of quality variations during the room-temperature curing of the polishing tape in a rolled state, and has replaced the urethane resin with a polyester having a specific constitution. The present inventors have found that a polishing tape suitable for polishing a thin-film magnetic disk which can reduce the variation in quality generated during reaction curing by using a resin can be obtained, and have completed the present invention.

[0008]

According to the present invention, there is provided a process for preparing a coating solution by mixing abrasive grains, a binder and a solvent as main components, and applying the coating solution on a substrate to form a coating film. Drying the solvent to remove the solvent, and thereby curing the binder, the method for producing a polishing tape,

The binder in the step of preparing the coating solution has the following composition:

Embedded image An epoxy resin having a number average molecular weight of 1,000 to 5,000 having a repeating unit of

(B) a condensate of an aromatic dicarboxylic acid and / or an aliphatic dicarboxylic acid and an aliphatic diol in the molecule, having a number average molecular weight of 10,000 to 30,000, having at least a terminal hydroxyl group, and A polyester resin having a glass transition point (Tg) of -20C to 40C, and

(C) The object of the present invention has been successfully solved by providing a method for producing a polishing tape characterized by containing a polyfunctional isocyanate.

In the present invention, the base material for the polishing tape on which the polishing layer is formed includes polyethylene terephthalate, polypropylene, polycarbonate, acetate,
Various plastics such as polyvinyl chloride, aluminum and other films are suitable.

As described above, the coating liquid for forming the polishing layer applied on the base material for the polishing tape contains a compounded resin having a specific composition as a binder component. To achieve the desired hardness and change the hardness of the binder to the desired range.

Embedded image And a polymer having a number average molecular weight of 1,000 to 5,000 containing repeating units such as Sumitomo Chemical's solid epoxy resin ESA-
014 (number average molecular weight about 2000)

(2) A condensate structure of an aromatic dicarboxylic acid (eg, terephthalic acid, isophthalic acid), an aliphatic dicarboxylic acid (eg, sebacic acid, azelaic acid) and an aliphatic diol (eg, ethylene glycol, neopentyl glycol) Polyester resin contained in the molecule,
Glass transition temperature (Tg) having a number average molecular weight of 10,000 to 30,000 and having at least a terminal OH group of -20 ° C to 40 ° C
° C polymer, for example, a polyester resin Vylon 650 manufactured by Toyobo (average molecular weight: about 20,000, Tg: about 14).
° C), and

(3) It contains a polyfunctional isocyanate such as Coronate L manufactured by Nippon Polyurethane, and can be crosslinked and cured at room temperature.

The epoxy resin (1) used in the present invention must have a number average molecular weight of 1,000 to 5,000,
It is desirable that it is 1000-3000. Molecular weight 60
If it is more than 00, as shown in Table 1, the compatibility with the polyester resin is deteriorated, and phase separation is caused, so that it cannot be used. On the other hand 10
If it is less than 00, the number of OH groups in one molecule is small, so that the three-dimensional crosslinking density is not sufficiently increased.

The polyester resin used in the present invention must have a molecular weight of 10,000 to 30,000.
If it exceeds 30,000, the crosslink density becomes low, while 100
If it is less than 00, fluidity remains even after the solvent is removed by drying. Also T
If the g is too low, the hardness before crosslinking is not sufficient, and if the g is too high, the flexibility of the polishing tape is impaired.
° C. In addition, it is necessary to have an OH group at least at the terminal, but it is possible to have an OH group in the side chain.

As the polyfunctional isocyanate, an isocyanate compound having at least two or more isocyanate groups can be used. Usually, a trifunctional low molecular weight isocyanate obtained by reacting 1 mol of triol with 3 mol of diisocyanate is linear. It is used as a preferable one because the cross-linking between the polyester resins is also possible.

The solvent for the coating solution of the present invention includes
Ketone solvents such as methyl isobutyl ketone, methyl ethyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; aromatic hydrocarbon solvents such as benzene, toluene, and xylene; dioxane, tetrahydrofuran, dimethylformamide, and dimethyl sulfoxide alone Alternatively, a coating solution can be prepared by mixing two or more kinds.

Further, the abrasive grains, which are essential components in the coating solution for forming the polishing layer, include, for example, aluminum oxide, silicon carbide, silicon nitride, zirconium oxide, chromium oxide, iron oxide, diamond, boron nitride. , Emery and the like are used. If the particle size is less than 0.1 μm, the polishing efficiency of the obtained polishing tape is poor and the particle size is 1 μm.
If the thickness exceeds 00 μ, a polishing tape capable of performing precise finishing cannot be obtained.
An abrasive having a particle size of 00μ, preferably from about 0.1 to about 60μ, is used.

The coating liquid for forming the polishing layer may optionally contain additives such as a dispersant and an antistatic agent.

The coating liquid for forming a polishing layer is usually
The abrasive contains about 100 to 400 parts by weight with respect to 100 parts by weight of the binder, and is applied to a thickness of about 10 to 50 μ on a base material for a polishing tape.

[0023]

[Table 1]

The structure of the constituent resin of the binder is shown below.
Structural formula of raw resin

Embedded image RV65SS is a MEK / toluene solution of Byron 650 and has the same solid resin.

[0025]

EXAMPLES The method for producing a polishing tape of the present invention will be further described below with reference to examples.

Table 2 shows the change of the [0026] storage modulus at the glass transition point Tg and 25 ° C. at the time of changing the ratio of the physical properties the epoxy resin binder binder (ESA014) and polyester resin (Byron 650) E ' . The measured values were obtained by curing at 25 ° C. for one week and measuring with RSAII of Rheometrics. However, the amount of Coronate L was determined according to the following formula (1). Amount of coronate L (NCO equivalent) = (O of ESA019
H equivalent) × 1 + (OH equivalent of RV65SS) × 5─
(1)

[0027]

Table 2 ─────────────────────────────────── ESA014 / Byron 650 E '@ At 25 ° C ( dyn / cm ² ) Tg (° C) ─────────────────────────────────── 10/90 1.03 × 10 ¹⁰ 48 20/80 1.94 × 10 ¹⁰ 56 30/70 2.76 × 10 ¹⁰ 60 ────────────────────────── ────────

From Table 2, it can be seen that ESA014 and Byron 650 were used.
At least E ′ = 1.0
It can be seen that any hardness can be obtained in the range of 3 to 2.76 × 10 ¹⁰ dyn / cm ² . The change in the hardness of the binder can be understood from the change in the glass transition temperature Tg shown in the table, and can be used as a guide for setting the recipe.

Preparation of Polishing Tape A coating liquid having the compounding ratio shown in Table 3 was applied on a 24 μm thick polyester film to a coating width of 50 cm and a length of about 1200 m by a roll coater, and then dried and made of aluminum having a diameter of 6 inches. The film was wound around a winding shaft and cured at 25 ° C. The compounding values are shown in parts by weight.

[0030]

[Table 3] Composition of polishing tape (unit: parts by weight) 原 Hara Material name Example エ ポ キ シ Epoxy resin (ESA014) 2.84 Polyester resin (Byron 650) 25.61 MEK 60.55 Toluene 29.88 WA # 5000 (25μ Al ₂ O ₃ abrasive) 100 Coronate L 7.91 ２ Total 226.79７９ ───────

Characteristics of Polishing Tape For comparison with the examples, the reaction time and hardness at room temperature (25 ° C.) of a comparative example (components and compounding ratios are shown in Table 4) in which a polyurethane resin was used instead of the polyester resin were used. The relationship is shown in FIG.

[0032]

[Table 4] Formulation of polishing tape (comparative example) ─────────────────────────────────── Raw material Name Comparative Example ─────────────────────────────────── Epoxy resin (ESA019) 8.32 Urethane resin (EA1443 ) (Solid content 55% MEK / toluene solution) 28.10 MEK 74.30 WA # 4000 (3μ Al ₂ O ₃ abrasive) 100 Coronate L 14.15 ２ Total 224.87───────────────────────── ──────────

From FIG. 1, it can be seen that the coating layer is very soft in the initial stage and almost the same as the hardness of the substrate in the comparative example, whereas the coating layer has a certain hardness from the beginning in the embodiment. I understand. For this reason, the embodiment has resistance to the internal pressure in the roll, and does not easily change in quality.

FIG. 2 shows the relationship between the finish roughness of the substrate surface and the longitudinal position of the polishing tape in the roll when the NiP surface of the hard disk substrate was polished using the examples and comparative examples. In addition, the Example and the comparative example used what wound up in roll shape, and was hardened at 25 degreeC for 1 week.

FIG. 2 shows that the present invention can greatly reduce the change in finishability caused by the internal pressure in the roll during curing at room temperature in the state of being wound up in the form of a roll.

[0036]

Since the polishing layer of the polishing tape manufactured by the method of the present invention has a certain degree of hardness from the beginning, it changes due to the internal pressure in the roll during curing at room temperature in the state of being wound into a roll. Since it is difficult for the polishing tape to occur, it is possible to reduce the variation in the quality of the polishing tape such as the machinability and the finish, and to exhibit the performance particularly suitable for the polishing step of the thin-film magnetic disk.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the hardening time and the hardness (stickiness) of a polishing tape.

FIG. 2 is a graph showing the change in the finish of the polishing tape in the roll in the longitudinal direction.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-49-110728 (JP, A) JP-A-61-265279 (JP, A) JP-A-57-41170 (JP, A) 177412 (JP, A) JP-A-3-16661 (JP, A) US Pat. No. 4,267,288 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B24D 11/00 B24D 3/28 C08J 7/04 G11B 5/84

Claims (2)

(57) [Claims] An abrasive grain, a binder and a solvent as main components.
Preparing mixed and a coating liquid agent, in the coating solution Solvent was removed by drying after coating on a substrate a method of making an abrasive tape and a step of curing it by binding agent, wherein The binder in the step of preparing the coating liquid has the following composition: (A) (B) an aromatic dicarboxylic acid and / or a condensate of an aliphatic dicarboxylic acid and an aliphatic diol in the molecule, having a number average molecular weight of 10,000 to 30,000 Having a hydroxyl group at least at a terminal and having a glass transition point (Tg) of -2.
A method for producing a polishing tape, comprising: a polyester resin at 0 ° C to 40 ° C; and (C) a polyfunctional isocyanate. 2. The method for producing a polishing tape according to claim 1, further comprising a step of curing the binder at room temperature (25 ° C. ± 15 ° C.).