JP2010099771A - Polishing pad for glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing pad for glass which reduces generation of scratches while maintaining a high polishing rate for a long time. <P>SOLUTION: In the polishing pad 10 for glass, slurry composed mainly of a thermoplastic synthetic resin adhesive 14, a cerium oxide abrasive 16, and a surfactant 18 is impregnated into non-woven fabric 12 comprising synthetic fibers, and then is fixed thereto and is dried. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polishing pad for glass, and more particularly to a polishing pad for glass used for polishing a glass surface such as a glass substrate for display, a glass disk for a recording device, and an optical lens.

  Conventionally, as a polishing base material, a polishing pad (Patent Document 1) in which a cerium oxide abrasive is generally blended with a urethane resin closed foam pad, or a porous solid obtained by impregnating a non-woven felt with a polyurethane solution and wet coagulation treatment. A non-woven fabric sheet (Patent Document 2) is disclosed.

In recent years, with the increase in the size of glass materials used in the video field, the miniaturization, thinning, and high-density recording of substrates for magnetic recording media such as HDD (Hard Disk Drive), which is one of the magnetic recording media, The glass substrate is gradually being replaced by a glass substrate that is superior to the aluminum substrate in terms of flatness and substrate strength on the substrate surface. Therefore, there is a demand for a substrate that has a more uniform polishing force and can perform high-precision polishing.
Japanese Patent Application Laid-Open No. 07-116964 Japanese Patent Laid-Open No. 02-250776

  However, the polishing pad disclosed in Patent Document 1 has an excellent initial polishing rate, but due to the nature of independent foaming, problems such as clogging are likely to occur, and the polishing rate is not stable. Scratches are likely to occur due to the clogging. In addition, the porous nonwoven fabric sheet disclosed in Patent Document 2 is characterized by good retention of the polishing slurry supplied from good air permeability and is not easily clogged, but the pad itself is abrasive-free. Therefore, although there is a finishing effect by the supplied slurry, the polishing rate is low.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a glass polishing pad with less scratching while maintaining a high polishing rate.

  In the first aspect of the invention, the nonwoven fabric made of synthetic fibers is impregnated with a slurry mainly composed of a thermosetting synthetic resin adhesive, a cerium oxide abrasive, and a surfactant, and then fixed and dried. This is a polishing pad for glass.

  Invention of Claim 2 is a polishing pad for glass of Claim 1 whose hardness is Shore A hardness 80-90.

  Invention of Claim 3 is a polishing pad for glass of Claim 1 or Claim 2 whose compounding quantity of the cerium oxide abrasive | polishing agent in the polishing pad for glass is 10 to 60 weight%.

  According to the polishing pad for glass according to the present invention, clogging due to slurry and polishing residue during polishing is suppressed, and the cerium oxide abrasive is uniformly fixed on the fiber surface of the nonwoven fabric, thereby achieving high polishing. Polishing at a rate can be performed for a long time, and generation of scratches can be reduced.

FIG. 1 is an external view of an embodiment of a polishing pad for glass according to the present invention.
FIG. 2 is an enlarged illustrative view showing an enlarged part of an embodiment of a polishing pad for glass according to the present invention.

  The structure of the polishing pad 10 for glass concerning this invention is demonstrated. The glass polishing pad 10 includes a nonwoven fabric 12, a thermosetting synthetic resin adhesive 14, a cerium oxide abrasive 16, and a surfactant 18. The thermosetting synthetic resin adhesive 14 and the cerium oxide abrasive 16 are impregnated into the nonwoven fabric 12 together with the surfactant 18 and fixed and dried.

  Hereafter, each element which comprises the polishing pad 10 for glass is explained in full detail, and the point etc. which this invention is excellent with respect to the conventional polishing pad for glass are demonstrated.

  The nonwoven fabric 12 is produced by needle punching a fiber assembly (cross web) obtained by opening synthetic fibers with a card machine. The nonwoven fabric 12 may use a parallel web (card method), a random web (airlaid method), a spunbond method, or a papermaking method in place of the crossweb, but the crossweb and span can be controlled in terms of controlling thickness and density. The bond method is desirable, and in addition, it is preferable that a needle punch and a water needle are applied. The constituent fibers of the fiber assembly are not particularly limited, but those having a fiber diameter in the range of 5 μm to 50 μm are used, and within this range, those having the same fiber diameter or different fiber diameters may be combined. Can be used. In order to impart uniformity and air permeability of the polishing pad, those having a fiber diameter in the range of 10 μm to 20 μm are preferable. The type of constituent fiber is not particularly limited as long as it has a certain strength, but polyamide fiber, aramid fiber, polyester fiber, and vinylon fiber can be selected singly or in combination, water resistance, chemical resistance From the viewpoints of properties and rigidity, polyester fibers are preferred. In addition, as a method of increasing the density of the fiber assembly, a latent crimp type can be arbitrarily blended, and crimps can be expressed with a hot roll to achieve high density and high modulus.

  The thermosetting synthetic resin adhesive 14 fixes the cerium oxide abrasive 16 to the nonwoven fabric 12. The thermosetting synthetic resin adhesive 14 can be selected from urethane resin, phenol resin, epoxy resin, etc., but can strongly bond the non-woven fabric 12 and the cerium oxide abrasive 16 and impart high elasticity to the pad. A urethane resin is preferred.

  The cerium oxide abrasive 16 preferably has an average particle size in the range of 0.7 to 2 μm. If the average particle size is 2 μm or more, it becomes easy to make deep scratches on the glass, and if it is 0.7 μm or less, a sufficient polishing rate cannot be obtained. The blending amount of the cerium oxide abrasive 16 is preferably 10 to 60% by weight, more preferably 30 to 55% by weight, based on the entire polishing pad for glass. When the amount is 10% by weight or less, the fixed abrasive does not exhibit the effect sufficiently, and when the amount is 60% by weight or more, the adhesiveness of the adhesive is inhibited and the durability is lowered.

  The surfactant 18 is soluble in a solvent for diluting the thermosetting synthetic resin adhesive 14, and can uniformly disperse the cerium oxide abrasive 16 in the solvent and adhere to the nonwoven fabric 12 uniformly. If it is, it will not be restrict | limited in particular.

  The nonwoven fabric 12 is impregnated with a slurry in which a thermosetting synthetic resin adhesive 14, a cerium oxide abrasive 16, and a surfactant 18 are mixed in an arbitrary ratio. As the fixing method, an immersion method, a spray method, or a coating method may be used alone or in combination. The nonwoven fabric 12 to which the slurry is fixed is dried using a known drying method. At this time, the nonwoven fabric 12 must be dried at a temperature at which the nonwoven fabric 12 is not denatured and at a temperature at which the thermosetting synthetic resin adhesive 14 can be sufficiently cured. As shown in FIG. 2, the cerium oxide abrasive 16 is uniformly fixed to the surface of the constituent fibers of the dried nonwoven fabric 12 by a thermosetting synthetic resin adhesive 14.

Since the polishing pad 10 for glass has the unevenness | corrugation resulting from the nonwoven fabric 12 on the surface, it sands grinding | polishing processing on both surfaces and improves flatness. Thereby, a pad with a predetermined thickness can be manufactured. In addition, embossing or grooving can be performed on one surface so that polishing slurry can be smoothly supplied and discharged on the polishing surface. The hardness of the glass polishing pad 10 is preferably in the range of 80 to 90 in Shore A hardness. If the Shore A hardness is 80 or less, a load is applied to only a part of the polishing surface, so uniform polishing cannot be performed. If the Shore A hardness is 90 or more, the pad becomes too hard and may cause scratches.
In addition, in order to fix the polishing pad 10 for glass to a polishing machine surface plate, an industrial double-sided adhesive tape can be used for one side.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these. The desired polishing pad 10 for glass should just be produced by changing suitably in the range described in the claim.

After blending 70% of polyester fiber of 3.3 dtex and 30% of latent crimpable polyester of 2.8 dtex, the fiber assembly (cross web) opened by a card machine is subjected to needle punching, The latent crimpability was expressed with a roll, and the nonwoven fabric 12 having a basis weight of 260 g / m ² and a thickness of 2.0 mm was produced. Then, a thermosetting urethane resin as the thermosetting synthetic resin adhesive 14 and a cerium oxide abrasive 16 having an average particle size of 0.95 μm are added to the nonwoven fabric 12 with a surfactant 18 (ester type nonionic). The dispersed slurry was impregnated. The composition of the thermosetting urethane resin, the cerium oxide abrasive 16 and the surfactant 18 was 100: 265: 10 in solid ratio. The amount of impregnation of the slurry into the nonwoven fabric 12 was impregnated so that the dry solid content was 740 g / m ² . Then, this nonwoven fabric 12 was fixed and dried, and both surfaces were sanded by 0.25 mm to remove irregularities, whereby a circular polishing pad 10 for glass of Example 1 was obtained. Incidentally, each data of Example 1, thickness 1.5 mm, density 0.5 g / cm ^3, a Shore A hardness 85, was amount 54 wt% of cerium oxide.

Although it produced by the process substantially the same as Example 1, it adjusted so that the Shore A hardness 87 and the compounding quantity of cerium oxide might be 33 weight%, and Example 2 was produced.
(Comparative Example 1)
A comparative example 1 was prepared by adjusting the density to 0.4 g / cm ³ , Shore A hardness 78, and cerium oxide content of 33 wt%.
(Comparative Example 2)
A comparative example 2 was prepared in the same manner as in Example 1 except that the density was 0.6 g / cm ³ , the Shore A hardness was 92, and the blending amount of cerium oxide was 55% by weight.
(Comparative Example 3)
A urethane foam cerium pad generally used for glass polishing was used. (Conventional product)
Table 1 shows the specifications of each example and comparative example.

（研磨方法）
それぞれの研磨パッドの裏面に工業用両面テープを貼付し、ポリッシングマシン（光永産業社製精密研磨機ＭＦＬＮ４．３Ｂ（両面研磨））に装着して、被研磨物として２０ｍｍ×２０ｍｍ×２ｍｍのソーダガラス（青板）をそれぞれの例について６枚ずつ研磨した。研磨液としては酸化セリウム研磨剤７％水分散液を使用し、加工荷重１．９ｋＰａ、定盤回転数７０ｒｐｍの条件下で実施した。
（研磨評価）
評価は、平均研磨レートと仕上げ精度を比較して行った。平均研磨レートは、３０分間×２回処理後（初期）と×１５〜１６回処理（中期）を実施した際の被研磨物厚さ平均摩耗量を求め、単位時間（分）当たりの厚み減少量（μｍ／分）で算出した。仕上がり精度は、Ｚｙｇｏ社製「ＮｅｗＶｉｅｗ２００」を用いて、３０分間×５回処理後（初期）と×１６回処理後の被研磨物仕上精度（端部表面状態及びスクラッチの有無及び表面粗さ）を測定し、評価結果を表２に示した。

(Polishing method)
Attach industrial double-sided tape to the back of each polishing pad, attach it to a polishing machine (Precision polishing machine MFLN4.3B (double-side polishing) by Mitsunaga Sangyo Co., Ltd.), and use 20 mm x 20 mm x 2 mm soda glass (Blue plate) was polished 6 sheets for each example. As the polishing liquid, a 7% aqueous dispersion of cerium oxide abrasive was used, and the processing was performed under the conditions of a processing load of 1.9 kPa and a platen rotational speed of 70 rpm.
(Polishing evaluation)
The evaluation was performed by comparing the average polishing rate and the finishing accuracy. Average polishing rate is 30 minutes x 2 times after treatment (initial) and x15 to 16 times treatment (medium term), and the average thickness of the workpiece is determined, and the thickness decreases per unit time (minutes). The amount was calculated (μm / min). Finishing accuracy is Zygo's “NewView 200”, 30 minutes × 5 times after treatment (initial) and × 16 times after finishing workpiece finish accuracy (end surface condition, presence or absence of scratches and surface roughness) The results of evaluation are shown in Table 2.

○（良好、従来品と同等以上）、△ （一部劣る、一部悪い）、△×（不良に近い）、× （不良、劣る）の４段階で相対評価した。

O (good, equal to or better than conventional products), Δ (partially inferior, partly bad), Δ × (nearly defective), × (defect, inferior) were evaluated in four stages.

  As is apparent from Table 2, it was confirmed that Example 1 and Example 2 maintained stable polishing performance with respect to the polishing rate, the end surface condition of the object to be polished, scratches, and surface roughness. In Comparative Example 1, since the density and hardness are low, the polishing rate reduction rate due to the nonwoven fabric base is good, but the polishing rate itself is low, the corners of the object to be polished are rounded, and the end surface condition is deteriorated. . In Comparative Example 2, on the contrary, since the density and hardness were high, the end surface condition was good, but scratches occurred in the medium-term polishing.

1 is an external view of an embodiment of a polishing pad for glass according to the present invention. It is the expansion solution figure which expanded a part of one embodiment of the polish pad for glass concerning the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Polishing pad for glass 12 Nonwoven fabric 14 Thermosetting synthetic resin adhesive 16 Cerium oxide abrasive 18 Surfactant

Claims (3)

To non-woven fabric made of synthetic fibers,
A polishing pad for glass, which is impregnated with a slurry mainly composed of a thermosetting synthetic resin adhesive, a cerium oxide abrasive, and a surfactant and then fixed and dried.   The polishing pad for glass according to claim 1 whose hardness is Shore A hardness 80-90.   The polishing pad for glass of Claim 1 or Claim 2 whose compounding quantity of the cerium oxide abrasive | polishing agent in a polishing pad for glass is 10 to 60 weight%.

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