JP3100075B2 - 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 used for forming a polishing layer in which a polishing resin made of an inorganic powder and a thermoplastic resin, a thermosetting resin, or a reactive resin as a binder are dispersed in a solvent. Is generally formed by applying the above-mentioned coating liquid on a substrate, and then performing a post-treatment according to the type of resin in the coating liquid.

In recent years, polishing tapes using a polyester resin having a molecular weight of about 20,000 and crosslinked with a trifunctional isocyanate have been widely used as a binder.

[0004]

When such a binder is used, the reaction rate with an isocyanate is low because the concentration of OH groups in the polyester resin is low.
Required a high reaction temperature of 36 hours or about 80 hours at 50 ° C. In addition, since it has to be cured at such a high temperature in the state of being wound up in a roll shape, the cutting property, finishability, etc. are affected by variations in internal pressure and temperature distribution due to tension and the like when winding up in a roll shape. However, there is a defect that the quality as a polishing tape changes and the quality of the product varies.

[0005] 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. there were.

The present inventors have conducted intensive studies on a binder for polishing tapes, and have found a binder which can obtain a sufficient reaction rate even when the reaction temperature is lowered to room temperature and which can obtain a high crosslinking density. It was completed.

[0007]

The present invention has succeeded in solving the above problems by providing the following method for producing a polishing tape.

That is, a step of preparing a coating solution by mixing abrasive grains, a binder and a solvent as main components, a step of applying the coating solution on a substrate and then drying, and a step of removing the solvent to remove the binder In a method for producing a polishing tape including a step of curing

In the step of preparing the coating solution, the binder has the following composition:

Embedded image A polymer having an average molecular weight of 1,000 to 10,000 containing repeating units of

(Ii) a polyurethane resin having a number average molecular weight of 5,000 to 20,000 and having an OH group at a terminal;

(Iii) It contains a polyfunctional isocyanate, and (iv) the weight ratio of the component (i) to the component (ii) is 10:90 to 4
A method for producing a polishing tape characterized by being in the range of 0:60 has been provided by the present invention.

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 binder having a specific structure, and achieves the intended purpose. As a hard polymer so that the hardness of the binder can be changed to a desired range, the formula

Embedded image Is mixed in a ratio of 10:90 to 40:60 with a first polymer having a repeating unit as a repeating unit and a second polymer containing a soft polyurethane resin such as polycaprolactone as a repeating unit and having at least a terminal OH group. And further adding a polyfunctional isocyanate to add O 2 in the first and second polymers.
The crosslinking is carried out by the reaction between the H group and the isocyanate.

The molecular weight (number average) of the first polymer used in the present invention must be 1,000 to 10,000. In the case of a polymer having a molecular weight of more than 10,000 (for example, phenoxy resin PKHH manufactured by U.C. U.S.A.), the compatibility of the system becomes poor, and the dispersibility of the abrasive grains may decrease.
On the other hand, if it is less than 1,000, the number of OH groups per molecule becomes small, so that the three-dimensional crosslinking density does not sufficiently increase.

The molecular weight of the second polymer is 5,000 to 5,000.
Must be 20,000. If the molecular weight exceeds 20,000, the crosslinking density decreases, while if it is less than 5,000, the fluidity of the resin does not disappear even after the solvent is removed by drying.

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, and 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 utilized.

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.

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

Binder resin (1) Raw materials : The following raw materials were used as components of the binder. (a) Epoxy resin (Sumitomo Chemical: ESA019)

Embedded image

(B) Urethane resin (manufactured by Daicel: EA14)
43) A urethane resin containing Mn ≒ 12000 and polycaprolactone diol in the main chain.

(C) Trifunctional isocyanate (Coronate L, manufactured by Nippon Polyurethane)

Embedded image

(2) Physical Properties of Binder Resin Epoxy resin (ESA019) and urethane resin (EA1)
Table 1 shows the changes in the glass transition point Tg and the storage modulus E 'at 25 ° C. when the ratio of 443) was changed. 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).

The amount of coronate L (NCO equivalent) = (ES
(OH equivalent of A019) x 1 + (OH equivalent of EA1443) x 3 (1)

[0025]

[Table 1] ─────────────────────────────────── ESA019 / EA1443 (by.wt) E '( dyn / cm ² ) Tg (° C) ─────────────────────────────────── 10/90 1.82 ^{× 10 8 0 25/75 2.11 × 10} 9 44 30/70 4.89 × 10 9 49 35/65 1.52 × 10 10 64 40/60 1.91 × 10 10 65 ────── ────────────────────────────

From Table 1, it can be seen that by changing the mixing ratio between ESA019 and EA1443, at least E '= 1.8.
It can be seen that any hardness is obtained between 2 × 10 ^{8 and} 1.91 × 10 ¹⁰ dyn / cm ² . The change in the hardness of the binder can be understood from the change in the glass transition point Tg shown in Table 1, and can be used as a guide for setting the recipe.

Also, ESA019 / EA1443 = 25
FIG. 1 shows the change in storage modulus E ′ of / 75 with temperature. Compared with the conventionally used polyester resin binder PE307 shown in FIG. 2 which is cross-linked with coronate L, which is a trifunctional isocyanate, E ′ is almost the same at room temperature, whereas in the rubber region It can be seen that E ′ is high. Thereby, the binder system according to the present invention has a higher crosslinking density than that of the conventional binder,
As a result, it can be expected that there is little change in quality during storage of the product.

Production of Polishing Tape (Examples 1 and 2) A coating solution having the compounding ratio shown in Table 2 was applied on a 24 μm thick polyester film by a knife coater over an application width of about 10 cm and a length of about 50 m. It was dried, wound around a 3 inch diameter vinyl chloride core, and cured. In addition, compounding numerical value shows a weight part.

[0029]

[Table 2] Table 2. Composition of polishing tape ─────────────────────────────────── Raw material name Example 1 Example 2 ─ ────────────────────────────────── ESA019 55.60 49.93 (50% MEK solution) EA1443 75. 78 84.29 (50% MEK / toluene solution) MEK 146.04 197.93 300.00 300.00 WA # 4000 (3 μ Al ₂ O ₃ abrasive) Coronate L 44.91 42.44 ───────────────────────────── Total 622.328 674.59────────────── ────────────────────

Table 3 shows the curing conditions of each example.

[Table 3]

[0031] shown in Figure 2 the cutting results when polished brass with a polishing tape belt grinding tests according to the characteristics of these examples of the polishing tape. From FIG. 3, the curing temperature was changed from 70 ° C. to room temperature (2
It can be seen that when the temperature is lowered to 5 ± 15 ° C., the variation in the machinability due to the position in the longitudinal direction in the roll is reduced. It can also be seen that, despite the softness of the binder, Example 2 cured at room temperature had less variation than Example 1 cured at 70 ° C.

[0032]

The polishing layer in the polishing tape manufactured by the manufacturing method of the present invention has abrasive grains bonded with a binder hardened at room temperature having a specific structure described in the claims. Excellent effect of high cross-linking density, small variation in the state in which the polishing tape is wound into a roll after storage and storage of the product, and good storage stability,
It is effective.

[Brief description of the drawings]

FIG. 1 is a graph showing a change in storage elastic modulus E ′ of a binder of a polishing tape according to an embodiment of the present invention with temperature.

FIG. 2 is a graph showing the change in storage modulus of a conventional polyester binder with temperature.

FIG. 3 is a graph showing a change in a cutting property of a polishing tape in a roll in a longitudinal direction.

Continuation of the front page (56) References JP-A-49-110728 (JP, A) JP-A-61-265279 (JP, A) JP-A-60-137980 (JP, A) JP-A-59-30817 (JP) JP-A-3-166612 (JP, A) JP-A-3-177412 (JP, A) JP-A-57-41170 (JP, A) US Patent 4,267,288 (US, A) (58) (Int.Cl. ⁷ , DB name) B24D 11/00 B24D 3/28 C08J 7/04 G11B 5/84

Claims (3)

(57) [Claims] 1. A process for preparing a coating liquid by mixing abrasive grains, a binder and a solvent as main components, a step of applying the coating liquid on a substrate and then drying, and a step of curing the binder. In the method for producing a polishing tape, the binder in the step of preparing the coating liquid has a component composition represented by the formula (i): A polymer having an average molecular weight of 1,000 to 10,000 containing a repeating unit of (ii) a polyurethane resin having a number average molecular weight of 50
A polymer having an OH group at the terminal, (iii) containing a polyfunctional isocyanate, and (iv) a weight ratio of the component (i) to the component (ii) of 10: 90-4.
A method for producing a polishing tape, characterized by being in the range of 0:60. 2. The method according to claim 1, wherein the polyurethane resin contains polycaprolactone as a repeating unit. 3. 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.).