JP4832789B2

JP4832789B2 - Polishing cloth

Info

Publication number: JP4832789B2
Application number: JP2005120440A
Authority: JP
Inventors: 大介高橋
Original assignee: Fujibo Holdins Inc
Current assignee: Fujibo Holdins Inc
Priority date: 2005-04-19
Filing date: 2005-04-19
Publication date: 2011-12-07
Anticipated expiration: 2025-04-19
Also published as: JP2006297515A

Description

本発明は研磨布に係り、特に、湿式成膜法により形成され、スキン層と、スキン層の内側に位置する発泡層とを有し、研磨加工による摩耗を許容する軟質プラスチックシートを備えた研磨布に関する。 The present invention relates to a polishing cloth, and in particular, a polishing provided with a soft plastic sheet formed by a wet film forming method, having a skin layer and a foam layer positioned inside the skin layer, and allowing abrasion by polishing processing. Regarding cloth.

従来、レンズ、平行平面板、反射ミラー等の光学材料、ハードディスク用アルミニウム基板、シリコンウエハ、液晶ディスプレイ用ガラス基板等の材料（被研磨物）では、高精度な平坦性が要求されるため、研磨布を使用した研磨加工が行われている。通常、研磨加工時には、被研磨物の両面又は片面に研磨布を対向させ研磨粒子等を含む研磨液（スラリ）が被研磨物及び研磨布間に供給されている。 Conventionally, optical materials such as lenses, plane-parallel plates and reflecting mirrors, hard disk aluminum substrates, silicon wafers, glass substrates for liquid crystal displays, etc. (polished objects) require high-precision flatness, so polishing Polishing using cloth is performed. Usually, at the time of polishing, a polishing liquid (slurry) containing abrasive particles or the like is supplied between the object to be polished and the polishing cloth with the polishing cloth facing both or one side of the object to be polished.

ハードディスク用アルミニウム基板等の精密仕上げ用研磨布は、微多孔が形成された表面層（スキン層）と、表面層の内側に位置する発泡層とを有し、研磨加工による摩耗を許容する軟質プラスチックシートを備えている。この軟質プラスチックシートは、水混和性の有機溶媒に軟質プラスチックを溶解させ得られた樹脂溶液をシート状の基材に塗布後、水系凝固液中で樹脂を凝固再生させること（湿式成膜法）で製造されている。凝固再生に伴い軟質プラスチックシートの表面には表面層を構成する微多孔が厚さ数μｍ程度に亘り緻密に形成され、表面層の内側には発泡層を構成する多数の発泡が連続して形成される。通常、これらの発泡の孔径は、表面層に近づくほど小さくなる円錐状（断面略三角状）を呈している。 A polishing cloth for precision finishing such as an aluminum substrate for hard disks is a soft plastic that has a surface layer (skin layer) in which micropores are formed and a foam layer positioned inside the surface layer, and allows wear due to polishing. It has a seat. This soft plastic sheet is obtained by applying a resin solution obtained by dissolving a soft plastic in a water-miscible organic solvent to a sheet-like substrate and then coagulating and regenerating the resin in an aqueous coagulation liquid (wet film-forming method) Manufactured by. Along with the coagulation regeneration, micropores constituting the surface layer are densely formed on the surface of the soft plastic sheet with a thickness of several μm, and numerous foams constituting the foam layer are continuously formed inside the surface layer. Is done. Usually, the pore diameter of these foams has a conical shape (substantially triangular shape in cross section) that decreases as the surface layer is approached.

微多孔が緻密に形成された表面層の表面は、平坦性に優れているため、研磨加工で被研磨物の表面の平坦性を向上させることが期待できる。その反面、表面層の表面は平滑性にも富んでいるため、研磨加工時に研磨液を被研磨物の表面及び表面層の表面間で保持することが難しい、という問題がある。このため、研磨加工時に供給した研磨液が被研磨物の表面及び表面層の表面間から流出し、研磨加工の効率が低下し研磨加工ができなくなることもある。これを解決するため、研磨加工時には表面層の表面がドレッシング処理（軽度の表面サンディング）されている（例えば、特許文献１参照）。 Since the surface of the surface layer in which micropores are densely formed has excellent flatness, it can be expected that the flatness of the surface of the object to be polished will be improved by polishing. On the other hand, since the surface of the surface layer is rich in smoothness, it is difficult to hold the polishing liquid between the surface of the object to be polished and the surface of the surface layer during polishing. For this reason, the polishing liquid supplied at the time of the polishing process flows out from between the surface of the object to be polished and the surface of the surface layer, the efficiency of the polishing process is lowered, and the polishing process may be impossible. In order to solve this problem, the surface of the surface layer is subjected to dressing (light surface sanding) during polishing (for example, see Patent Document 1).

また、表面層の厚さが数μｍ程度であり研磨加工の進行に伴い軟質プラスチックシートが磨耗するため、発泡層に形成された発泡が開孔する。従来の研磨布では、研磨液の保持のため、表面層側をバフ処理し、３０〜４０μｍ開孔させたものを使用している。通常の湿式成膜法で形成される従来の研磨布では、研磨面（表面層の表面）での孔径が大きすぎるため、研磨加工すると被研磨物の表面の平坦性を向上させることが難しい。平坦性を向上させるため、従来バフ処理で除去されていた発泡層の表面層近傍の孔径の小さい微細発泡を利用した研磨布が開示されている（例えば、特許文献２参照）。この研磨布によれば、研磨加工時に微細発泡が開孔しても孔径が小さいため、平坦性の向上を図ることができる。また、うねりやスクラッチ（キズ）の低減のため、研磨布の開孔径は、２５μｍ以下が望ましいとされている（例えば、特許文献３参照）。 Further, since the thickness of the surface layer is about several μm and the soft plastic sheet is worn as the polishing process proceeds, the foam formed in the foam layer is opened. In the conventional polishing cloth, in order to hold | maintain polishing liquid, the surface layer side is buff-processed and the thing made 30-40 micrometers opening is used. In a conventional polishing cloth formed by a normal wet film forming method, the pore diameter on the polishing surface (surface layer surface) is too large, and therefore it is difficult to improve the flatness of the surface of the object to be polished when polishing. In order to improve the flatness, a polishing cloth using fine foam having a small pore diameter in the vicinity of the surface layer of the foam layer that has been removed by buffing has been disclosed (for example, see Patent Document 2). According to this polishing cloth, even if fine foam is opened during polishing, the hole diameter is small, so that the flatness can be improved. In addition, in order to reduce waviness and scratches (scratches), the opening diameter of the polishing pad is preferably 25 μm or less (see, for example, Patent Document 3).

特開２００１−６２７０４号公報JP 2001-62704 A 特開２００４−２４３４４５号公報JP 2004-243445 A 特開２００５−１０１９号公報Japanese Patent Laid-Open No. 2005-1019

しかしながら、より平坦性を高める仕上げ研磨においては、研磨加工に有効な平均開孔径は概ね３０μｍ以下、より好ましく２５μｍ以下であるため、特許文献１、特許文献２の技術では、軟質プラスチックシートの摩耗が少ないうちは開孔径も小さいが、摩耗が増えると開孔径が大きくなり、被研磨物の平坦性を損なうこととなる。従って、微細発泡が形成されていても、仕上げ研磨加工に利用可能な軟質プラスチックシートの厚さは表面層から約１０％以下に過ぎない。被研磨物の平坦性を向上させるためには、開孔径が大きくなる前に研磨布の交換が必要となり、研磨布の寿命という点で劣っている。 However, in finish polishing that further improves flatness, the average hole diameter effective for polishing is approximately 30 μm or less, more preferably 25 μm or less. As long as the amount is small, the hole diameter is small. However, as wear increases, the hole diameter increases and the flatness of the object to be polished is impaired. Therefore, even if the fine foam is formed, the thickness of the soft plastic sheet that can be used for the finish polishing is only about 10% or less from the surface layer. In order to improve the flatness of the object to be polished, it is necessary to replace the polishing cloth before the aperture diameter becomes large, which is inferior in terms of the life of the polishing cloth.

本発明は上記事案に鑑み、被研磨物の平坦性を向上させることができ長寿命の研磨布を提供することを課題とする。 An object of the present invention is to provide a polishing cloth that can improve the flatness of an object to be polished and has a long life.

上記課題を解決するために、本発明は、湿式成膜法により形成され、スキン層と、前記スキン層の内側に位置する発泡層とを有し、研磨加工による摩耗を許容する軟質プラスチックシートを備えた研磨布において、前記発泡層には、前記スキン層側に偏って形成された第１の発泡と、前記発泡層の厚さ方向の長さが前記第１の発泡より長い第２の発泡とが略均等に形成されており、前記第１及び第２の発泡は、断面略三角状であり、連通孔で連通しているとともに、前記第１及び第２の発泡の孔径は、前記スキン層側で縮径されており、かつ、前記スキン層から内側の方向に前記軟質プラスチックシートの厚さの少なくとも１５％を超えるまで平均２５μｍ以下であることを特徴とする。 In order to solve the above-described problems, the present invention provides a soft plastic sheet that is formed by a wet film forming method, includes a skin layer and a foam layer positioned inside the skin layer, and allows wear due to polishing. In the polishing cloth provided, the foam layer includes a first foam formed to be biased toward the skin layer side, and a second foam in which a length in the thickness direction of the foam layer is longer than the first foam. And the first and second foams have a substantially triangular cross section and communicate with each other through communication holes, and the pore diameters of the first and second foams are defined by the skin. It is reduced in diameter on the layer side, and has an average of 25 μm or less until it exceeds at least 15% of the thickness of the soft plastic sheet in the inner direction from the skin layer.

本発明では、軟質プラスチックシートがスキン層を有するため、スキン層の平坦な表面で被研磨物を研磨加工することができ、スキン層が摩耗して発泡層に略均等に形成された第１及び第２の発泡が開孔しても、第１及び第２の発泡が連通孔で連通しており、第１及び第２の発泡の孔径がスキン層側で縮径されているため、研磨加工時に研磨粒子を含む研磨液が第１及び第２の小さな孔径で断面略三角状の発泡に貯留されつつ連通孔を通じて移動することから、被研磨物及び軟質プラスチックシート間に略均等に供給され、被研磨物の表面が第１及び第２の発泡の小さな間隔で研磨加工されるので、被研磨物の表面の平坦性を向上させることができると共に、発泡層が摩耗しても、スキン層から内側の方向に軟質プラスチックシートの厚さの少なくとも１５％を超えるまで第１及び第２の発泡の孔径が平均２５μｍ以下のため、この範囲で研磨加工を継続して行うことができるので、研磨布の寿命を向上させることができる。 In the present invention, since the flexible plastic sheet having a skin layer, it can be polished object to be polished with a flat surface of the skin layer, the first and the skin layer is substantially uniformly formed on the foamed layer worn Even if the second foam is opened, the first and second foams communicate with each other through the communication holes, and the pore diameters of the first and second foams are reduced on the skin layer side. Since the polishing liquid containing the abrasive particles sometimes moves through the communication hole while being stored in the foam having a substantially triangular shape in cross section with the first and second small holes , it is supplied substantially evenly between the object to be polished and the soft plastic sheet , the surface of the object to be polished is polished by the first and short distance of the second foam Runode, it is possible to improve the flatness of the surface of the object to be polished, even if the foam layer is worn, the skin layer The thickness of the soft plastic sheet in the inner direction For the hole diameter of the first and second bubble to over 15% average 25μm or less even without, it is possible to continuously perform a polishing in this range, it is possible to improve the lifetime of the polishing pad.

この場合において、発泡層の第１及び第２の発泡の孔径が、スキン層から内側の方向に軟質プラスチックシートの厚さの少なくとも２０％を超えるまで平均２５μｍ以下であることが好ましい。また、発泡層の第１及び第２の発泡の合計数を、第１及び第２の発泡の孔径が平均２５μｍ以下の部分でスキン層に沿う方向の１ｍｍあたり３０個以上としてもよい。また、第２の発泡が、発泡層の厚さのほぼ全体に亘る長さで略一様に形成されており、第１の発泡が、第２の発泡間に形成されており、発泡層の厚さ方向の長さにバラツキを有していてもよい。更に、第１及び第２の発泡が、軟質プラスチックシート作製用の軟質プラスチック溶液に添加された親水性添加剤で形成されてもよい。この親水性添加剤としては、アニオン界面活性剤又はノニオン界面活性剤を挙げることができる。このとき、軟質プラスチックシートを、液体が非浸透性の可撓性フィルムに軟質プラスチック溶液が塗布され形成されたものとすれば、湿式成膜時に当該可撓性フィルム側では脱溶媒が生じないので、第１及び第２の発泡を断面略三角状に形成することができる。更に、軟質プラスチックシートのスキン層と反対側に、少なくとも可撓性フィルム、不織布及び織布から選択される１種であり、軟質プラスチックシートを支持する支持層を更に備えていてもよい。 In this case, it is preferable that the pore diameter of the first and second foams of the foam layer is 25 μm or less on average until it exceeds at least 20% of the thickness of the soft plastic sheet in the inner direction from the skin layer. Further, the total number of the first and second foams in the foam layer may be 30 or more per 1 mm in the direction along the skin layer in the portion where the pore diameter of the first and second foams is 25 μm or less on average. In addition, the second foam is formed substantially uniformly with a length over substantially the entire thickness of the foam layer, and the first foam is formed between the second foams, in the thickness direction to the length it may have a variation. Further, the first and second foams may be formed with a hydrophilic additive added to a soft plastic solution for making a soft plastic sheet. Examples of the hydrophilic additive include an anionic surfactant and a nonionic surfactant. At this time, the flexible plastic sheet, desolvation not occur in liquid impermeable flexible film to soft plastic solution is applied formed as a to lever, the flexible film side during wet film formation Therefore, the first and second foams can be formed in a substantially triangular cross section . Furthermore, on the side opposite to the skin layer of the soft plastic sheet, at least one kind selected from a flexible film, a nonwoven fabric and a woven fabric may be provided, and a support layer for supporting the soft plastic sheet may be further provided.

本発明によれば、軟質プラスチックシートがスキン層を有するため、スキン層の平坦な表面で被研磨物を研磨加工することができ、スキン層が摩耗しても、第１及び第２の発泡が連通孔で連通しており、第１及び第２の発泡の孔径がスキン層側で縮径されているため、研磨液が第１及び第２の小さな孔径で断面略三角状の発泡に貯留されつつ連通孔を通じて移動することから、被研磨物及び軟質プラスチックシート間に略均等に供給され、被研磨物の表面が第１及び第２の発泡の小さな間隔で研磨加工されるので、被研磨物の表面の平坦性を向上させることができると共に、発泡層が摩耗しても、スキン層から内側の方向に軟質プラスチックシートの厚さの少なくとも１５％を超えるまで第１及び第２の発泡の孔径が平均２５μｍ以下のため、この範囲で研磨加工を継続して行うことができるので、研磨布の寿命を向上させることができる、という効果を得ることができる。 According to the present invention, since the flexible plastic sheet having a skin layer, it can be polished object to be polished with a flat surface of the skin layer, even if the skin layer is worn, the first and second foam Since the pores of the first and second foams are reduced on the skin layer side, the polishing liquid is stored in the foam having a substantially triangular shape in cross section with the first and second small pore sizes. from moving through the communication hole while being substantially uniformly supplied between the workpiece and the flexible plastic sheet, the surface of the object to be polished is polished by the first and short distance of the second foam Runode, workpiece The surface diameter of the first and second foams can be improved until the foam layer wears out and the thickness of the soft plastic sheet exceeds at least 15% of the thickness of the soft plastic sheet inward from the skin layer. Is less than 25μm on average Since the polishing in this range can be continued, it is possible to improve the lifetime of the polishing pad, the effect can be obtained as.

以下、図面を参照して、本発明に係る研磨布の実施の形態について説明する。 Hereinafter, an embodiment of a polishing cloth according to the present invention will be described with reference to the drawings.

（研磨パッド）
図１に示すように、本実施形態の研磨パッド（一般に研磨パッドと称されるため、以下、研磨パッドという。）１は、ポリウレタン樹脂で形成された軟質プラスチックシートとしてのポリウレタンシート２を備えている。ポリウレタンシート２は、被研磨物を研磨加工する研磨面側に、図示しない緻密な微多孔が形成されたスキン層２ａを有しており、スキン層２ａの研磨面と反対側（内側）に、ナップ層２ｂ（発泡層）を有している。ナップ層２ｂには、ポリウレタンシート２の厚さ方向に沿って丸みを帯びた断面略三角状の発泡３（第２の発泡）と、発泡３より長さが短く断面略三角状の微細発泡４（第１の発泡）とが略均等に形成されている。 (Polishing pad)
As shown in FIG. 1, a polishing pad (generally referred to as a polishing pad, hereinafter referred to as a polishing pad) 1 of this embodiment includes a polyurethane sheet 2 as a soft plastic sheet formed of a polyurethane resin. Yes. Polyurethane sheet 2, the polishing surface side of polished object to be polished, has a skin layer 2 a a dense microporous formed (not shown), the polishing surface opposite the skin layer 2a (inside) And a nap layer 2b (foamed layer). The nap layer 2b includes a foam 3 having a substantially triangular cross section (second foam) rounded along the thickness direction of the polyurethane sheet 2 and a fine foam 4 having a substantially triangular cross section shorter than the foam 3 in length. (First foaming) are formed substantially evenly.

ナップ層２ｂに形成された発泡３は、ポリウレタンシート２の厚さのほぼ全体に亘る長さで略一様に形成されている。微細発泡４は、ナップ層２内のスキン層２ａ側に偏った位置で発泡３間に形成されており、ポリウレタンシート２の厚さ方向で長さにバラツキを有している。このため、略均等に形成された発泡３間に微細発泡４が略均等に形成されていることとなる。発泡３及び微細発泡４の孔径は、スキン層２ａに形成された図示しない微多孔より大きく、スキン層２ａ側の大きさがスキン層２ａの反対側より小さく形成されている。すなわち、発泡３及び微細発泡４は、スキン層２ａ側で縮径されている。発泡３及び微細発泡４は、スキン層２ａの微多孔より孔径の大きい図示を省略した連通孔で立体網目状に連通している。また、発泡３及び微細発泡４は、スキン層２ａからスキン層２ａの反対側方向にポリウレタンシート２の厚さの少なくとも１５％を超えるまで平均２５μｍ以下の孔径が維持されている。この範囲では、発泡３及び微細発泡４がスキン層２ａに沿う方向の長さ１ｍｍあたりで３０個以上形成されている。 The foam 3 formed in the nap layer 2b is formed substantially uniformly with a length over almost the entire thickness of the polyurethane sheet 2. The fine foam 4 is formed between the foams 3 at a position biased toward the skin layer 2 a in the nap layer 2, and has a length variation in the thickness direction of the polyurethane sheet 2. For this reason, the fine foam 4 is formed substantially uniformly between the foams 3 formed substantially uniformly. The pore diameters of the foam 3 and the fine foam 4 are larger than the micropore (not shown) formed in the skin layer 2a, and the size on the skin layer 2a side is smaller than the opposite side of the skin layer 2a. That is, the diameter of the foam 3 and the fine foam 4 is reduced on the skin layer 2a side. The foam 3 and the fine foam 4 communicate with each other in a three-dimensional mesh shape with communication holes having a larger pore diameter than the fine pores of the skin layer 2a, not shown. The foam 3 and the fine foam 4 have an average pore diameter of 25 μm or less on average until the thickness exceeds at least 15% of the thickness of the polyurethane sheet 2 from the skin layer 2a to the opposite side of the skin layer 2a. In this range, 30 or more foams 3 and fine foams 4 are formed per 1 mm length in the direction along the skin layer 2a.

また、研磨パッド１は、スキン層２ａと反対側に、ポリウレタンシート２を支持する支持材６を備えている。支持材６には、少なくともポリエチレンテレフタレート（以下、ＰＥＴと略記する。）製フィルム等の可撓性フィルム、不織布又は織布から選択される１種が使用されている。支持材６の下面側には、他面側（最下面側）に剥離紙８を有し研磨機に研磨パッド１を固着するための両面テープ７が貼り合わされている。 Further, the polishing pad 1 includes a support material 6 that supports the polyurethane sheet 2 on the side opposite to the skin layer 2a. As the support material 6, at least one kind selected from a flexible film such as a polyethylene terephthalate (hereinafter abbreviated as PET) film, a nonwoven fabric, or a woven fabric is used. On the lower surface side of the support member 6, a double-sided tape 7 having a release paper 8 on the other surface side (lowermost surface side) for fixing the polishing pad 1 to a polishing machine is bonded.

（研磨パッドの製造）
研磨パッド１は、図２に示す各工程を経て製造される。まず、準備工程では、ポリウレタン樹脂、ポリウレタン樹脂を溶解可能な水混和性の有機溶媒のＮ，Ｎ−ジメチルホルムアミド（以下、ＤＭＦと略記する。）、発泡３及び微細発泡４の形成させるための親水性添加剤を混合してポリウレタン樹脂を溶解させる。ポリウレタン樹脂には、ポリエステル系、ポリエーテル系、ポリカーボネート系等の樹脂から選択して用い、例えば、ポリウレタン樹脂が３０％となるようにＤＭＦに溶解させる。また、ポリウレタン樹脂の溶解時に、別の添加剤として、カーボンブラック等の顔料、ポリウレタン樹脂の凝固再生を安定化させる疎水性活性剤等を適宜添加することができる。 (Manufacture of polishing pad)
The polishing pad 1 is manufactured through each process shown in FIG. First, in the preparation step, polyurethane resin, water-miscible organic solvent N, N-dimethylformamide (hereinafter abbreviated as DMF), foam 3 and fine foam 4 are formed. The polyurethane resin is dissolved by mixing the additive. As the polyurethane resin, a polyester resin, a polyether resin, a polycarbonate resin, or the like is selected and used. For example, the polyurethane resin is dissolved in DMF so as to be 30%. Further, when the polyurethane resin is dissolved, a pigment such as carbon black, a hydrophobic active agent that stabilizes the coagulation regeneration of the polyurethane resin, and the like can be appropriately added as other additives.

親水性添加剤としては、例えば、カルボン酸塩、スルホン酸塩、硫酸エステル塩、燐酸エステル塩等のアニオン界面活性剤を使用する。ポリウレタン樹脂に対する親水性添加剤の添加量は、発泡３及び微細発泡４のスキン層２ａ側での孔径、数に応じて設定する。得られた混合溶液を濾過することで凝集塊等を除去した後、真空下で脱泡してポリウレタン樹脂溶液を得る。 As the hydrophilic additive, for example, an anionic surfactant such as carboxylate, sulfonate, sulfate ester salt, phosphate ester salt or the like is used. The amount of the hydrophilic additive added to the polyurethane resin is set according to the pore diameter and number of the foam 3 and fine foam 4 on the skin layer 2a side. The obtained mixed solution is filtered to remove aggregates and the like, and then defoamed under vacuum to obtain a polyurethane resin solution.

塗布工程、凝固再生工程及び洗浄・乾燥工程では、準備工程で得られたポリウレタン樹脂溶液を成膜基材に連続的に塗布し、水系凝固液に浸漬することでポリウレタン樹脂を凝固再生させ、洗浄後乾燥させてポリウレタンシート２を得る。塗布工程、凝固再生工程及び洗浄・乾燥工程は、図３に示す成膜装置で連続して実行される。 In the coating process, coagulation regeneration process, and washing / drying process, the polyurethane resin solution obtained in the preparation process is continuously applied to the film-forming substrate and immersed in an aqueous coagulation liquid to coagulate and regenerate the polyurethane resin, followed by washing. Thereafter, the polyurethane sheet 2 is obtained by drying. The coating process, the coagulation regeneration process, and the cleaning / drying process are continuously executed by the film forming apparatus shown in FIG.

図３に示すように、成膜装置６０は、成膜基材の不織布や織布を前処理する、水又はＤＭＦ水溶液（ＤＭＦと水との混合液）等の前処理液１５が満たされた前処理槽１０、ポリウレタン樹脂を凝固再生させるための、ポリウレタン樹脂に対して貧溶媒である水を主成分とする凝固液２５が満たされた凝固槽２０、凝固再生後のポリウレタン樹脂を洗浄する水等の洗浄液３５が満たされた洗浄槽３０及びポリウレタン樹脂を乾燥させるためのシリンダ乾燥機５０を連続して備えている。 As shown in FIG. 3, the film forming apparatus 60 is filled with a pretreatment liquid 15 such as water or a DMF aqueous solution (mixed liquid of DMF and water) that pretreats a nonwoven fabric or a woven cloth of a film forming substrate. Pretreatment tank 10, coagulation tank 20 filled with coagulation liquid 25 mainly composed of water which is a poor solvent for polyurethane resin for coagulating and regenerating polyurethane resin, water for washing polyurethane resin after coagulation and regeneration A cleaning tank 30 filled with a cleaning liquid 35 such as the above and a cylinder dryer 50 for drying the polyurethane resin are continuously provided.

前処理槽１０の上流側には、成膜基材４３を供給する基材供給ローラ４１が配置されている。前処理槽１０は、成膜基材４３の搬送方向と同じ長手方向の略中央部の内側下部に一対のガイドローラ対１３を有している。前処理槽１０の上方で、基材供給ローラ４１側にはガイドローラ１１、１２が配設されており、凝固槽２０側には前処理した成膜基材４３に含まれる過剰な前処理液１５を除去するマングルローラ１８が配置されている。マングルローラ１８の下流側には、成膜基材４３にポリウレタン樹脂溶液４５を略均一に塗布するナイフコータ４６が配置されている。ナイフコータ４６の下流側で凝固槽２０の上方にはガイドローラ２１が配置されている。 On the upstream side of the pretreatment tank 10, a substrate supply roller 41 that supplies a film forming substrate 43 is disposed. The pretreatment tank 10 has a pair of guide rollers 13 at the lower part inside the substantially central part in the same longitudinal direction as the transport direction of the film forming substrate 43. Above the pretreatment tank 10, guide rollers 11 and 12 are disposed on the substrate supply roller 41 side, and an excessive pretreatment liquid contained in the pretreated film forming substrate 43 is disposed on the coagulation tank 20 side. A mangle roller 18 for removing 15 is disposed. On the downstream side of the mangle roller 18, a knife coater 46 for applying the polyurethane resin solution 45 to the film forming substrate 43 substantially uniformly is disposed. A guide roller 21 is disposed on the downstream side of the knife coater 46 and above the coagulation tank 20.

凝固槽２０には、洗浄槽３０側の内側下部にガイドローラ２３が配置されている。凝固槽２０の上方で洗浄槽３０側には凝固再生後のポリウレタン樹脂を脱水処理するマングルローラ２８が配置されている。マングルローラ２８の下流側で洗浄槽３０の上方にはガイドローラ３１が配置されている。洗浄槽３０には、成膜基材４３の搬送方向と同じ長手方向で上部に４本、下部に５本のガイドローラ３３が上下交互となるように配設されている。洗浄槽３０の上方でシリンダ乾燥機５０側には、洗浄後のポリウレタン樹脂を脱水処理するマングルローラ３８が配置されている。シリンダ乾燥機５０には、内部に熱源を有する４本のシリンダが上下４段に配設されている。シリンダ乾燥機５０の下流側には、乾燥後のポリウレタン樹脂を（成膜基材４３と共に）巻き取る巻取ローラ４２が配置されている。なお、マングルローラ１８、２８、３８、シリンダ乾燥機５０及び巻取ローラ４２は、図示を省略した回転駆動モータに接続されており、これらの回転駆動力により成膜基材４３が基材供給ローラ４１から巻取ローラ４２まで搬送される。 In the coagulation tank 20, a guide roller 23 is disposed at the inner lower part on the cleaning tank 30 side. A mangle roller 28 is disposed on the washing tank 30 side above the coagulation tank 20 for dehydrating the polyurethane resin after coagulation regeneration. A guide roller 31 is disposed on the downstream side of the mangle roller 28 and above the cleaning tank 30. In the cleaning tank 30, four guide rollers 33 at the upper part and five guide rollers 33 at the lower part are arranged alternately in the vertical direction in the same longitudinal direction as the transport direction of the film forming substrate 43. A mangle roller 38 for dehydrating the washed polyurethane resin is disposed on the cylinder dryer 50 side above the cleaning tank 30. In the cylinder dryer 50, four cylinders having heat sources inside are arranged in four stages. On the downstream side of the cylinder dryer 50, a take-up roller 42 that winds up the dried polyurethane resin (together with the film forming substrate 43) is disposed. The mangle rollers 18, 28, 38, the cylinder dryer 50 and the take-up roller 42 are connected to a rotation drive motor (not shown), and the film formation substrate 43 is made to be a substrate supply roller by these rotation drive forces. It is conveyed from 41 to the winding roller 42.

成膜基材４３に不織布又は織布を用いる場合は、成膜基材４３が基材供給ローラ４１から引き出され、ガイドローラ１１、１２を介して前処理液１５中に連続的に導入される。前処理液１５中で一対のガイドローラ１３間に成膜基材４３を通過させて前処理（目止め）を行うことにより、ポリウレタン樹脂溶液４５を塗布するときに、成膜基材４３内部へのポリウレタン樹脂溶液４５の浸透が抑制される。成膜基材４３は、前処理液１５から引き上げられた後、マングルローラ１８で加圧されて余分な前処理液１５が絞り落とされる。前処理後の成膜基材４３は、凝固槽２０方向に搬送される。なお、成膜基材４３としてＰＥＴ製等の可撓性フィルムを用いる場合は、前処理が不要のため、ガイドローラ１２から直接マングルローラ１８に送り込むようにするか、又は、前処理槽１０に前処理液１５を入れないようにしてもよい。以下、本例では、成膜基材４３をＰＥＴ製フィルムとして説明する。 When a non-woven fabric or a woven fabric is used as the film forming substrate 43, the film forming substrate 43 is pulled out from the substrate supply roller 41 and continuously introduced into the pretreatment liquid 15 through the guide rollers 11 and 12. . When the polyurethane resin solution 45 is applied by passing the film-forming substrate 43 between the pair of guide rollers 13 in the pretreatment liquid 15 and performing the pretreatment (sealing), the film-forming substrate 43 is brought into the film forming substrate 43. Of the polyurethane resin solution 45 is suppressed. After the film forming substrate 43 is pulled up from the pretreatment liquid 15, it is pressurized by the mangle roller 18 and the excess pretreatment liquid 15 is squeezed out. The pre-processed film-forming substrate 43 is conveyed in the direction of the coagulation tank 20. In the case where a flexible film made of PET or the like is used as the film forming substrate 43, pretreatment is not necessary, so that the film is directly fed from the guide roller 12 to the mangle roller 18 or in the pretreatment tank 10. The pretreatment liquid 15 may not be added. Hereinafter, in this example, the film forming substrate 43 is described as a PET film.

図２に示すように、塗布工程では、準備工程で調製したポリウレタン樹脂溶液４５が常温下でナイフコータ４６により成膜基材４３に略均一に塗布される。このとき、ナイフコータ４６と成膜基材４３の上面との間隙（クリアランス）を調整することで、ポリウレタン樹脂溶液４５の塗布厚さ（塗布量）を調整する。 As shown in FIG. 2, in the application process, the polyurethane resin solution 45 prepared in the preparation process is applied almost uniformly to the film forming substrate 43 by the knife coater 46 at room temperature. At this time, the application thickness (application amount) of the polyurethane resin solution 45 is adjusted by adjusting the gap (clearance) between the knife coater 46 and the upper surface of the film forming substrate 43.

凝固再生工程では、ナイフコータ４６でポリウレタン樹脂溶液４５が塗布された成膜基材４３が、ガイドローラ２１からガイドローラ２３へ向けて凝固液２５中に導入される。凝固浴２５は、水を循環させることで常温に維持されている。凝固液２５中では、まず、塗布されたポリウレタン樹脂溶液４５の表面でポリウレタン樹脂溶液４５のＤＭＦと凝固液２５との置換が進行して緻密な微多孔が形成される。この微多孔は厚さ数μｍ程度に形成されスキン層２ａを構成する。その後、スキン層２ａ及び成膜基材４３間のポリウレタン樹脂溶液４５中のＤＭＦと凝固液２５との置換の進行によりポリウレタン樹脂が成膜基材４３の片面に凝固再生される。ＤＭＦの脱溶媒による凝固液２５との置換に伴い、スキン層４ａの内側には発泡３、微細発泡４、及び、発泡３、微細発泡４を立体網目状に連通する連通孔が形成されてナップ層４ｂを構成する。 In the coagulation regeneration process, the film forming substrate 43 coated with the polyurethane resin solution 45 by the knife coater 46 is introduced into the coagulation liquid 25 from the guide roller 21 toward the guide roller 23. The coagulation bath 25 is maintained at room temperature by circulating water. In the coagulating liquid 25, first, substitution of DMF of the polyurethane resin solution 45 and the coagulating liquid 25 proceeds on the surface of the applied polyurethane resin solution 45 to form dense micropores. The micropores are formed to a thickness of about several μm and constitute the skin layer 2a. Thereafter, the polyurethane resin is coagulated and regenerated on one surface of the film forming substrate 43 by the progress of substitution of the DMF in the polyurethane resin solution 45 and the coagulating liquid 25 between the skin layer 2 a and the film forming substrate 43. Along with the replacement of the DMF with the coagulation liquid 25 by desolvation, the foam 3, the fine foam 4, and the communication holes that connect the foam 3 and the fine foam 4 in a three-dimensional mesh shape are formed inside the skin layer 4 a. Layer 4b is formed.

ここで、発泡３及び微細発泡４の形成について説明すると、ポリウレタン樹脂溶液４５の凝固液２５との界面でポリウレタン樹脂が凝固再生するときに、ポリウレタン樹脂溶液４５に添加した親水性添加剤の作用で脱溶媒（凝固液２５の浸入）の生じるポイントが増加するため、微多孔の数が増加すると共に、樹脂溶液層への水の浸透性を向上させ、ＤＭＦの置換速度を増大させる。その後の脱溶媒がスキン層２ａの微多孔を通じて生じるため、スキン層２ａに形成された微多孔数が増加したことで脱溶媒が速やかに進行するので、発泡３及び微細発泡４の数が増加し孔径が小さくなると共に、細長い発泡が形成される。このため、発泡３及び微細発泡４は、スキン層２ａからポリウレタンシート２の厚さの少なくとも１５％を超えるまで平均２５μｍ以下の孔径が維持され、この範囲では、発泡３及び微細発泡４の数がスキン層２ａに沿う方向の長さ１ｍｍあたりで３０個以上となる。また、ＰＥＴ製フィルムの成膜基材４３が水を浸透させないため、脱溶媒がスキン層２ａ側でのみ生じることから、発泡３及び微細発泡４は成膜基材４３側がスキン層２ａ側より大きく形成され、発泡３及び微細発泡４を連通する連通孔の孔径は微多孔の孔径より大きくなる。 Here, the formation of the foam 3 and the fine foam 4 will be described. The action of the hydrophilic additive added to the polyurethane resin solution 45 when the polyurethane resin coagulates and regenerates at the interface of the polyurethane resin solution 45 with the coagulation liquid 25. Since the point at which desolvation (infiltration of the coagulation liquid 25) increases, the number of micropores increases, the water permeability to the resin solution layer is improved, and the substitution rate of DMF is increased. Since the subsequent desolvation occurs through the micropores of the skin layer 2a, the desolvation proceeds promptly due to the increase in the number of micropores formed in the skin layer 2a, so that the number of foams 3 and microfoams 4 increases. As the pore size decreases, an elongated foam is formed. For this reason, the foam 3 and the fine foam 4 maintain an average pore diameter of 25 μm or less from the skin layer 2a to at least 15% of the thickness of the polyurethane sheet 2, and within this range, the number of the foam 3 and the fine foam 4 is 30 or more per 1 mm length in the direction along the skin layer 2a. Further, since the film-forming substrate 43 of the PET film does not permeate water, desolvation occurs only on the skin layer 2a side. Therefore, the foam 3 and the fine foam 4 are larger on the film-forming substrate 43 side than the skin layer 2a side. The hole diameter of the communication hole formed and communicating with the foam 3 and the fine foam 4 is larger than the pore diameter of the micropore.

ポリウレタン樹脂の凝固再生は、ポリウレタン樹脂溶液４５が塗布された成膜基材４３が凝固液２５中に進入してからガイドローラ２３に到る間に完了する。凝固再生したポリウレタン樹脂は、凝固液２５から引き上げられ、マングルローラ２８で余分な凝固液２５が絞り落とされた後、ガイドローラ３１を介して洗浄槽３０に搬送され洗浄液３５中に導入される。 The solidification regeneration of the polyurethane resin is completed while the film-forming substrate 43 coated with the polyurethane resin solution 45 enters the coagulating liquid 25 and reaches the guide roller 23. The coagulated and regenerated polyurethane resin is pulled up from the coagulating liquid 25, and after the excess coagulating liquid 25 is squeezed out by the mangle roller 28, the polyurethane resin is conveyed to the cleaning tank 30 via the guide roller 31 and introduced into the cleaning liquid 35.

図２に示すように、洗浄・乾燥工程では、洗浄液３５中に導入されたポリウレタン樹脂をガイドローラ３３に上下交互に通過させることによりポリウレタン樹脂が洗浄される。洗浄後、ポリウレタン樹脂は洗浄液３５から引き上げられ、マングルローラ３８で余分な洗浄液３５が絞り落とされる。その後、ポリウレタン樹脂を、シリンダ乾燥機５０の４本のシリンダ間を交互（図３の矢印方向）に、シリンダの周面に沿って通過させることで乾燥させる。乾燥後のポリウレタン樹脂（ポリウレタンシート２）は、成膜基材４３と共に巻取ローラ４２に巻き取られる。なお、成膜基材４３は、そのまま支持材６を構成する。 As shown in FIG. 2, in the cleaning / drying step, the polyurethane resin introduced into the cleaning liquid 35 is passed through the guide roller 33 alternately up and down to clean the polyurethane resin. After the cleaning, the polyurethane resin is pulled up from the cleaning liquid 35 and the excess cleaning liquid 35 is squeezed out by the mangle roller 38. Thereafter, the polyurethane resin is dried by passing along the circumferential surface of the cylinder alternately between the four cylinders of the cylinder dryer 50 (in the direction of the arrow in FIG. 3). The dried polyurethane resin (polyurethane sheet 2) is taken up by the take-up roller 42 together with the film-forming substrate 43. The film forming substrate 43 constitutes the support material 6 as it is.

ラミネート加工工程では、ポリウレタンシート２のスキン層２ａと反対側の支持材６の裏面側には、他面側に剥離紙８が貼付された両面テープ７を貼り合わせる。裁断・検査工程では、円形等の所望の形状に裁断した後、汚れや異物等の付着がないことを確認する等の検査を行い研磨パッド１を完成させる。 In the laminating process, the double-sided tape 7 having the release paper 8 attached to the other side is bonded to the back side of the support 6 opposite to the skin layer 2a of the polyurethane sheet 2. In the cutting / inspection step, after cutting into a desired shape such as a circle, an inspection is performed to confirm that there is no adhesion of dirt or foreign matter, and the polishing pad 1 is completed.

得られた研磨パッド１で被研磨物の研磨加工を行うときは、例えば、両面研磨機の上定盤、下定盤に両面テープ７を介してそれぞれ研磨パッド１を貼着する。両面研磨機では、被研磨物が上定盤及び下定盤にそれぞれ貼着された２枚の研磨パッド１間に挟まれて両面同時に研磨加工される。両面研磨機の研磨パッド１を貼着する面、すなわち、上定盤の下面及び下定盤の上面は、いずれも平坦に形成されている。このため、上定盤、下定盤に貼着された研磨パッド１では、被研磨物側の表面が略平坦となる。研磨液を供給し、上定盤及び下定盤間を加圧しながら回転させることで被研磨物を研磨加工する。 When polishing the object to be polished with the obtained polishing pad 1, for example, the polishing pad 1 is adhered to the upper surface plate and the lower surface plate of the double-side polishing machine via the double-sided tape 7, respectively. In the double-side polishing machine, an object to be polished is sandwiched between two polishing pads 1 attached to an upper surface plate and a lower surface plate, and both surfaces are simultaneously polished. The surface to which the polishing pad 1 of the double-side polishing machine is attached, that is, the lower surface of the upper surface plate and the upper surface of the lower surface plate are both formed flat. For this reason, in the polishing pad 1 adhered to the upper surface plate and the lower surface plate, the surface of the object to be polished becomes substantially flat. A polishing liquid is supplied, and an object to be polished is polished by rotating the upper surface plate and the lower surface plate while applying pressure.

（作用）
次に、本実施形態の研磨パッド１の作用等について説明する。 (Function)
Next, the operation and the like of the polishing pad 1 of the present embodiment will be described.

従来湿式成膜法で作製されるポリウレタンシートでは、図４（Ｂ）に示すように、ナップ層７２ｂに発泡７３と、発泡７３より長さが短くスキン層７２ａ側に偏った位置に微細発泡７４とが形成されているものの、発泡７３及び微細発泡７４の孔径がスキン層７２ａから離れるに従い大きく増大している。このため、従来のポリウレタンシートでは、研磨加工に有効な平均２５μｍ以下の孔径が矢印Ｑで示す範囲となり、ポリウレタンシートの厚さの１０％にも満たない範囲に過ぎない。また、発泡７３及び微細発泡７４の孔径が大きく増大するため、スキン層７２ａに沿う方向の１ｍｍあたりの数も３０個未満となる。このようなポリウレタンシートを用いた研磨パッドで被研磨物を研磨加工すると、スキン層７２ａの表面が平坦性に優れるため、スキン層７２ａの厚さの範囲では被研磨物を平坦に研磨加工することができる。スキン層７２ａが摩耗するとナップ層７２ｂの発泡７３及び微細発泡７４が開孔するが、摩耗が少ないうちは孔径も小さいため、研磨加工を継続することができる。ところが、研磨加工の継続に伴いポリウレタンシートの摩耗が進行すると比較的短時間で発泡７３及び微細発泡７４の孔径が大きくなるため、被研磨物の平坦性を損なうこととなる。被研磨物の平坦性を向上させるためには、孔径が大きくなる前に研磨布の交換が必要となることから、研磨布の寿命という点で劣っている。本実施形態の研磨パッド１は、これらの問題を解決することができるものである。 In the conventional polyurethane sheet produced by the wet film forming method, as shown in FIG. 4 (B), the foam 73 is formed in the nap layer 72b, and the fine foam 74 is shorter in the length than the foam 73 and biased toward the skin layer 72a. However, the pore diameters of the foam 73 and the fine foam 74 are greatly increased as the distance from the skin layer 72a is increased. For this reason, in the conventional polyurethane sheet, the average pore diameter of 25 μm or less effective for polishing is in the range indicated by the arrow Q, which is only a range less than 10% of the thickness of the polyurethane sheet. Further, since the pore diameters of the foam 73 and the fine foam 74 are greatly increased, the number per 1 mm in the direction along the skin layer 72a is also less than 30. When the object to be polished is polished with a polishing pad using such a polyurethane sheet, the surface of the skin layer 72a is excellent in flatness. Therefore, the object to be polished is polished flat within the thickness range of the skin layer 72a. Can do. When the skin layer 72a is worn, the foam 73 and the fine foam 74 of the nap layer 72b are opened. However, since the hole diameter is small while the wear is small, the polishing process can be continued. However, as the wear of the polyurethane sheet progresses as the polishing process continues, the pore diameters of the foam 73 and the fine foam 74 increase in a relatively short time, thereby impairing the flatness of the object to be polished. In order to improve the flatness of the object to be polished, since the polishing cloth needs to be replaced before the hole diameter becomes large, the life of the polishing cloth is inferior. The polishing pad 1 of this embodiment can solve these problems.

本実施形態のポリウレタンシート２では、図４（Ａ）に示すように、ナップ層２ｂに発泡３と、発泡３より長さが短くスキン層２ａ側に偏った位置に微細発泡４とが形成されている。スキン層２ａからポリウレタンシート２の厚さの１５％を超えるまで発泡３及び微細発泡４の孔径が平均２５μｍ以下に維持されているため、発泡３及び微細発泡４がポリウレタンシート２の厚さ方向で細長い形状となり、矢印Ｐで示す範囲が摩耗するまで研磨加工に使用することができる。従って、ポリウレタンシート２を用いた研磨パッド１では、平坦性に優れるスキン層２ａの表面で被研磨物を平坦に研磨加工することができると共に、スキン層２ａが摩耗してナップ層２ｂの発泡３及び微細発泡４が開孔しても、ポリウレタンシート２の厚さの少なくとも１５％を超えるまで孔径が平均２５μｍ以下のため、長期間に亘り被研磨物を平坦に研磨加工することができ、研磨パッド１の寿命を向上させることができる。 In the polyurethane sheet 2 of the present embodiment, as shown in FIG. 4A, the foam 3 is formed in the nap layer 2b, and the fine foam 4 is formed at a position that is shorter than the foam 3 and is biased toward the skin layer 2a. ing. Since the pore diameters of the foam 3 and the fine foam 4 are maintained at an average of 25 μm or less from the skin layer 2a to over 15% of the thickness of the polyurethane sheet 2, the foam 3 and the fine foam 4 are in the thickness direction of the polyurethane sheet 2. It becomes an elongated shape and can be used for polishing until the area indicated by the arrow P is worn. Therefore, in the polishing pad 1 using the polyurethane sheet 2, the object to be polished can be polished evenly on the surface of the skin layer 2a having excellent flatness, and the skin layer 2a is worn and foamed 3 of the nap layer 2b. Even if the fine foam 4 is opened, the average diameter of the pores is 25 μm or less until the thickness exceeds at least 15% of the thickness of the polyurethane sheet 2, so that the object to be polished can be polished flatly for a long period of time. The life of the pad 1 can be improved.

また、本実施形態の研磨パッド１では、発泡３及び微細発泡４がスキン層２ａに沿う方向の長さ１ｍｍあたり３０個以上の数で形成されており、ナップ層２ｂの全体に略均等に形成されている。このため、孔径が平均２５μｍ以下の発泡３及び微細発泡４の間隔が小さくなり、研磨粒子を含む研磨液が発泡３及び微細発泡４内に貯留されつつ研磨パッド１及び被研磨物間に略均等に供給される。これにより、被研磨物の表面が小さな間隔で研磨加工されるので、被研磨物の平坦性を向上させることができる。更に、本実施形態の研磨パッド１では、発泡３がナップ層２ｂの厚さのほぼ全体に亘る長さを有しているのに対して、スキン層２ａ側に偏って形成された微細発泡４の長さはバラツキを有している。発泡３及び微細発泡４がスキン層２ａ側で縮径された断面略三角状に形成されていることから、発泡３間に微細発泡４が略均等に形成されることで、スキン層２ａ側の発泡３及び微細発泡４の数を確保することができる。 Moreover, in the polishing pad 1 of this embodiment, the foam 3 and the fine foam 4 are formed in the number of 30 or more per 1 mm in the length along the skin layer 2a, and are formed almost uniformly on the entire nap layer 2b. Has been. For this reason, the interval between the foam 3 and the fine foam 4 having an average pore diameter of 25 μm or less is reduced, and the polishing liquid containing the abrasive particles is substantially uniformly distributed between the polishing pad 1 and the object to be polished while being stored in the foam 3 and the fine foam 4. To be supplied. As a result, the surface of the object to be polished is polished at a small interval, so that the flatness of the object to be polished can be improved. Furthermore, in the polishing pad 1 of the present embodiment, the foam 3 has a length that covers almost the entire thickness of the nap layer 2b, whereas the fine foam 4 that is formed biased toward the skin layer 2a side. The length of has a variation. Since the foam 3 and the fine foam 4 are formed in a substantially triangular shape with a reduced diameter on the skin layer 2a side, the fine foam 4 is formed substantially evenly between the foams 3, so that the skin layer 2a side The number of foams 3 and fine foams 4 can be ensured.

更に、本実施形態の研磨パッド１では、発泡３及び微細発泡４がスキン層２ａの微多孔より孔径の大きい連通孔で連通している。このため、研磨液が連通孔を通じて発泡３及び微細発泡４間を移動することから、被研磨物及び研磨パッド１間に研磨液を略均等に供給することができる。 Furthermore, in the polishing pad 1 of this embodiment, the foam 3 and the fine foam 4 communicate with each other through a communication hole having a larger pore diameter than the fine pores of the skin layer 2a. For this reason, since the polishing liquid moves between the foam 3 and the fine foam 4 through the communication hole, the polishing liquid can be supplied substantially evenly between the object to be polished and the polishing pad 1.

また更に、本実施形態では、ポリウレタンシート２の製造時にポリウレタン樹脂溶液４５に親水性添加剤が添加される。このため、ポリウレタン樹脂の凝固再生時にＤＭＦの脱
溶媒が生じるポイントが増加してスキン層２ａの微多孔の数が増加する。これにより、製造工程を複雑化することなく研磨パッド１のナップ層２ｂに細長形状の発泡３及び微細発泡４を容易に形成することができる。 Furthermore, in the present embodiment, a hydrophilic additive is added to the polyurethane resin solution 45 when the polyurethane sheet 2 is manufactured. For this reason, the point at which DMF desolvation occurs during the coagulation regeneration of the polyurethane resin increases, and the number of micropores in the skin layer 2a increases. Thereby, the elongated foam 3 and the fine foam 4 can be easily formed in the nap layer 2b of the polishing pad 1 without complicating the manufacturing process.

更にまた、本実施形態の研磨パッド１では、ポリウレタンシート２のスキン層２ａと反対側にＰＥＴ製フィルムの支持材６が貼り合わされている。このため、柔軟なポリウレタンシート２が支持材６に支持されるので、研磨パッド１の搬送時や研磨機への装着時の取り扱いを容易にすることができる。 Furthermore, in the polishing pad 1 of the present embodiment, a PET film support 6 is bonded to the opposite side of the polyurethane sheet 2 to the skin layer 2a. For this reason, since the flexible polyurethane sheet 2 is supported by the support material 6, the handling at the time of conveyance of the polishing pad 1 or attachment to a polishing machine can be facilitated.

なお、本実施形態の研磨パッド１では、親水性添加剤としてアニオン界面活性剤を例示したが、本発明はこれに限定されるものではなく、ポリウレタン樹脂の溶解に使用する有機溶媒に可溶性で親水性のものであればよい。このような親水性添加剤としては、例えば、親水性のエステル系、エーテル系、エステル・エーテル系、アミド系等のノニオン界面活性剤等を挙げることができる。また、これらの親水性添加剤の２種以上を混合して使用してもよい。 In the polishing pad 1 of the present embodiment, the anionic surfactant is exemplified as the hydrophilic additive, but the present invention is not limited to this, and is soluble in the organic solvent used for dissolving the polyurethane resin and hydrophilic. Anything of the nature is acceptable. Examples of such hydrophilic additives include hydrophilic ester-based, ether-based, ester-ether-based, amide-based nonionic surfactants, and the like. Two or more of these hydrophilic additives may be mixed and used.

また、ポリウレタン樹脂溶液４５に添加する親水性添加剤の添加量は、発泡３及び微細発泡４のスキン層２ａ側での孔径、数に応じて設定すればよく、特に制限されるものではない。親水性添加剤の添加量を大きくすることでスキン層２ａの微多孔の数を増加させることができる。微多孔の数が増加すると、脱溶媒の生じるポイントが増えるため、発泡３及び微細発泡４の孔径が小さくなり数が増加する。親水性添加剤の添加量は、添加剤の種類や樹脂の種類によって異なるが、例えば、樹脂溶液１００部に対して０．２〜５部の間で添加する。親水性添加剤の添加量が少なければ、発泡形状に変化がなく、多すぎれば、成膜性に支障をきたす。 The amount of the hydrophilic additive added to the polyurethane resin solution 45 may be set according to the pore diameter and number of the foam 3 and fine foam 4 on the skin layer 2a side, and is not particularly limited. By increasing the amount of the hydrophilic additive, the number of micropores in the skin layer 2a can be increased. As the number of micropores increases, the number of points where solvent removal occurs increases, so the pore diameters of the foam 3 and microfoam 4 become smaller and the number increases. Although the addition amount of a hydrophilic additive changes with kinds of additive and the kind of resin, for example, it adds between 0.2-5 parts with respect to 100 parts of resin solutions. If the addition amount of the hydrophilic additive is small, the foamed shape does not change, and if it is too much, the film formability is hindered.

更に、本実施形態の研磨パッド１では、ポリウレタン樹脂溶液４５に親水性添加剤を添加し、凝固浴２５を常温に維持してポリウレタン樹脂を凝固再生させる例を示したが、本発明はこれに制限されるものではない。例えば、凝固浴２５に冷水を循環させること等で凝固浴２５を低温に維持してポリウレタン樹脂を凝固再生させることもできる。凝固浴２５を低温とした場合には、常温に維持する場合と比較して、ポリウレタン樹脂溶液４５と凝固浴２５との界面でポリウレタン樹脂の凝固再生の進行が遅くなり（スキン層２ａの形成が遅くなり）、界面でポリウレタン樹脂が凝固再生する間での脱溶媒の進行に伴い微多孔の形成が促進されてスキン層２ａの微多孔の数が増加するため、発泡３及び微細発泡４の孔径が小さくなる。従って、例えば、アルミニウム基板の仕上げ研磨加工用等で孔径を小さくする場合には、凝固浴２５を低温に維持しておくことが好ましい。 Furthermore, in the polishing pad 1 of the present embodiment, an example has been shown in which a hydrophilic additive is added to the polyurethane resin solution 45 and the coagulation bath 25 is maintained at room temperature to coagulate and regenerate the polyurethane resin. It is not limited. For example, the polyurethane resin can be coagulated and regenerated by maintaining the coagulation bath 25 at a low temperature by circulating cold water through the coagulation bath 25. When the coagulation bath 25 is set to a low temperature, the progress of the coagulation regeneration of the polyurethane resin is delayed at the interface between the polyurethane resin solution 45 and the coagulation bath 25 as compared with the case where the coagulation bath 25 is maintained at a normal temperature (the formation of the skin layer 2a). The pore diameters of the foam 3 and the fine foam 4 are increased because the number of micropores in the skin layer 2a is increased as the desolvation progresses while the polyurethane resin coagulates and regenerates at the interface. Becomes smaller. Therefore, for example, when the hole diameter is reduced for finishing polishing of an aluminum substrate, it is preferable to keep the coagulation bath 25 at a low temperature.

また更に、本実施形態の研磨パッド１では、ポリウレタンシート２の成膜基材４３をＰＥＴ製フィルムの支持材６とする例を示したが、本発明はこれに限定されるものではなく、例えば、成膜基材４３を不織布や織布等としてもよい。また、ＰＥＴ製フィルムの成膜基材４３からポリウレタンシート２を剥離し、ポリウレタンシート２を単体で研磨機に固着するようにしてもよい。この場合に、例えば、ＰＥＴ製フィルム等の基材の両面に粘着剤が塗布された両面テープ７を使用すれば、容易に定盤に固定することができる。 Furthermore, in the polishing pad 1 of the present embodiment, an example in which the film forming substrate 43 of the polyurethane sheet 2 is used as the PET film support 6 is shown, but the present invention is not limited to this. The film forming substrate 43 may be a nonwoven fabric or a woven fabric. Alternatively, the polyurethane sheet 2 may be peeled off from the film-forming substrate 43 of the PET film, and the polyurethane sheet 2 may be fixed to the polishing machine alone. In this case, for example, if a double-sided tape 7 in which an adhesive is applied to both surfaces of a substrate such as a PET film is used, it can be easily fixed to a surface plate.

更にまた、本実施形態の研磨パッド１では、軟質プラスチックシートとしてのポリウレタンシート２の材質にポリエステル系、ポリエーテル系、ポリカーボネート系等のポリウ
レタン樹脂を例示したが、本発明はこれに限定されるものではなく、例えば、ポリエステル樹脂等を用いてもよい。ポリウレタン樹脂を用いれば、湿式成膜法で容易にスキン層２ａを形成することができる。更に、本実施形態では、ポリウレタン樹脂を３０％となるようにＤＭＦに溶解する例を示したが、本発明はこれに限定されるものではなく、ポリウレタン樹脂溶液４５の粘性やポリウレタンシート２の厚さ等により適宜変更してもよい。また、本実施形態では、ポリウレタン樹脂溶液４５の塗布にナイフコータ４６を例示したが、例えば、リバースコータ、ロールコータ等を用いてもよく、成膜基材４３に略均一な厚さに塗布可能であれば特に制限されるものではない。更に、本実施形態では、ポリウレタン樹脂の乾燥にシリンダ乾燥機５０を例示したが、本発明はこれに限定されるものではなく、例えば、熱風乾燥機等を用いてもよい。 Furthermore, in the polishing pad 1 of this embodiment, the polyurethane sheet 2 as a soft plastic sheet is exemplified by a polyurethane resin such as polyester, polyether, polycarbonate, etc., but the present invention is not limited to this. Instead, for example, a polyester resin or the like may be used. If a polyurethane resin is used, the skin layer 2a can be easily formed by a wet film forming method. Furthermore, in the present embodiment, an example in which the polyurethane resin is dissolved in DMF so as to be 30% is shown, but the present invention is not limited to this, and the viscosity of the polyurethane resin solution 45 and the thickness of the polyurethane sheet 2 are not limited thereto. It may be appropriately changed depending on the situation. In the present embodiment, the knife coater 46 is exemplified for applying the polyurethane resin solution 45. However, for example, a reverse coater, a roll coater, or the like may be used, and the film forming substrate 43 can be applied with a substantially uniform thickness. There is no particular limitation as long as it is present. Further, in the present embodiment, the cylinder dryer 50 is exemplified for drying the polyurethane resin, but the present invention is not limited to this, and for example, a hot air dryer or the like may be used.

以下、本実施形態に従い製造した研磨パッド１の実施例について説明する。なお、比較のために製造した比較例の研磨パッドについても併記する。 Hereinafter, examples of the polishing pad 1 manufactured according to the present embodiment will be described. A comparative polishing pad manufactured for comparison is also shown.

（実施例１）
下表１に示すように、実施例１では、ポリウレタン樹脂として、ポリエステルＭＤＩ（ジフェニルメタンジイソシアネート）ポリウレタン樹脂を用いた。このポリウレタン樹脂のＤＭＦ溶液１００部に対して、親水性添加剤のラウリル硫酸ナトリウム（ＳＬＳ）を１部添加し、更に、粘度調整用のＤＭＦの４５部、顔料のカーボンブラックを３０％含むＤＭＦ分散液の４０部、疎水性活性剤の２部を混合してポリウレタン樹脂溶液４５を調製した。ポリウレタン樹脂溶液４５を塗布する際に塗布装置のクリアランスを０．８ｍｍに設定した。凝固再生工程で凝固浴２５の温度を低温（１５°Ｃ）に維持し、洗浄工程での洗浄効果を高めるために凝固再生後の洗浄を温水で行った。なお、ポリウレタンシート２の単位面積あたりの重量から換算するとポリウレタン樹脂溶液４５の塗布量は、６７６ｇ／ｍ^２（固形換算１５１ｇ／ｍ^２）である。 Example 1
As shown in Table 1 below, in Example 1, polyester MDI (diphenylmethane diisocyanate) polyurethane resin was used as the polyurethane resin. 1 part of a hydrophilic additive sodium lauryl sulfate (SLS) is added to 100 parts of a DMF solution of this polyurethane resin, and further 45 parts of DMF for viscosity adjustment and a DMF dispersion containing 30% of pigment carbon black. A polyurethane resin solution 45 was prepared by mixing 40 parts of the liquid and 2 parts of the hydrophobic active agent. When applying the polyurethane resin solution 45, the clearance of the coating device was set to 0.8 mm. In the coagulation regeneration process, the temperature of the coagulation bath 25 was maintained at a low temperature (15 ° C.), and the washing after the coagulation regeneration was performed with warm water in order to enhance the cleaning effect in the cleaning process. In addition, when converted from the weight per unit area of the polyurethane sheet 2, the coating amount of the polyurethane resin solution 45 is 676 g / m ² (solid conversion 151 g / m ² ).

（実施例２）
表１に示すように、実施例２では、凝固浴２５を常温に維持すること以外は実施例１と同様にした。 (Example 2)
As shown in Table 1, Example 2 was the same as Example 1 except that the coagulation bath 25 was maintained at room temperature.

（比較例１）
表１に示すように、比較例１では、親水性添加剤を添加せず、凝固浴２５を常温に維持すること以外は実施例１と同様にした。従って、比較例１の研磨パッドは、従来の研磨パッドである（図４（Ｂ）参照）。 (Comparative Example 1)
As shown in Table 1, Comparative Example 1 was the same as Example 1 except that the hydrophilic additive was not added and the coagulation bath 25 was maintained at room temperature. Therefore, the polishing pad of Comparative Example 1 is a conventional polishing pad (see FIG. 4B).

（評価）
各実施例及び比較例の研磨パッドについて、発泡３及び微細発泡４の孔径及び数を以下のようにして測定した。成膜したポリウレタンシート２の断面写真（走査型電子顕微鏡）から、スキン層２ａからポリウレタンシート２の厚さの５％、１０％、１５％、２０％、３０％の位置に形成された発泡３及び微細発泡４の平均孔径及びスキン層２ａに沿う方向の１ｍｍあたりの発泡数を測定した。発泡数の測定結果を下表２に、孔径の測定結果を下表３にそれぞれ示した。 (Evaluation)
About the polishing pad of each Example and the comparative example, the hole diameter and number of the foam 3 and the fine foam 4 were measured as follows. From a cross-sectional photograph (scanning electron microscope) of the formed polyurethane sheet 2, foam 3 formed at a position of 5%, 10%, 15%, 20%, 30% of the thickness of the polyurethane sheet 2 from the skin layer 2a. And the average pore diameter of the fine foam 4 and the number of foams per mm in the direction along the skin layer 2a were measured. The measurement results of the number of foams are shown in Table 2 below, and the measurement results of the pore diameters are shown in Table 3 below.

表２及び表３に示すように、親水性添加剤を添加せず、常温で凝固再生させた比較例１のポリウレタンシートでは、厚さの１０％の位置で発泡数が２３個／ｍｍ、平均孔径が２４．２μｍを示している。厚さの割合が大きくなるほど発泡数が減少し、平均孔径が大きくなることを示している。平均孔径が２５μｍ以下ではあるが、発泡数が３０個／ｍｍ未満のため、スラリの貯液・供給には劣っている。このため、比較例１のポリウレタンシートを用いた研磨パッドでは、研磨加工時のポリウレタンシートの摩耗に伴い発泡及び微細発泡の孔径が増大して数が減少する。従って、ポリウレタンシートの厚さの１０％にも達しないうちに研磨パッドが寿命となり、このまま研磨加工を継続すると被研磨物の平坦性の低下を招くこととなる。これに対して、親水性添加剤を添加し、凝固浴２５を低温に維持して凝固再生させた実施例１のポリウレタンシート２では、厚さの２０％を超えるまで、発泡数３０個／ｍｍ以上、平均孔径２５μｍ以下を示した。また、親水性添加剤を添加し、凝固浴２５を常温に維持して凝固再生させた実施例２のポリウレタンシート２では、厚さの１５％を超えるまで、発泡数３０個／ｍｍ以上、平均孔径２５μｍ以下を示した。このことから、実施例１のポリウレタンシート２では、実施例２のポリウレタンシート２と比較して、発泡３及び微細発泡４がより細長く形成されることが判った。 As shown in Tables 2 and 3, in the polyurethane sheet of Comparative Example 1 which was coagulated and regenerated at room temperature without adding a hydrophilic additive, the number of foams was 23 / mm at the position of 10% of the thickness. The pore diameter is 24.2 μm. As the thickness ratio increases, the number of foams decreases and the average pore diameter increases. Although the average pore diameter is 25 μm or less, since the number of foams is less than 30 / mm, it is inferior in storing and supplying slurry. For this reason, in the polishing pad using the polyurethane sheet of Comparative Example 1, the pore diameter of foaming and fine foaming increases and the number decreases as the polyurethane sheet wears during polishing. Therefore, the polishing pad has a life before it reaches 10% of the thickness of the polyurethane sheet. If the polishing process is continued as it is, the flatness of the object to be polished will be lowered. On the other hand, in the polyurethane sheet 2 of Example 1 in which a hydrophilic additive was added and the coagulation bath 25 was maintained at a low temperature and coagulated and regenerated, the number of foams was 30 / mm until the thickness exceeded 20%. The average pore diameter was 25 μm or less. In addition, in the polyurethane sheet 2 of Example 2 in which a hydrophilic additive was added and the coagulation bath 25 was maintained at room temperature to be coagulated and regenerated, the number of foams was 30 / mm or more on average until the thickness exceeded 15%. The pore diameter was 25 μm or less. From this, in the polyurethane sheet 2 of Example 1, it turned out that the foam 3 and the fine foam 4 are formed longer than the polyurethane sheet 2 of Example 2.

以上の測定結果から、親水性添加剤を添加することで、ポリウレタンシート２の厚さの１５％を超えるまで平均孔径が２５μｍ以下に維持することができ、凝固浴２５を低温に維持することで、ポリウレタンシート２の厚さの２０％を超えるまで平均孔径が２５μｍ以下に維持することができることが判明した。従って、実施例１、実施例２の研磨パッド１では、長期間に亘り研磨加工を継続することができ、研磨パッド１の寿命を向上させることができることが明らかとなった。 From the above measurement results, by adding a hydrophilic additive, the average pore diameter can be maintained at 25 μm or less until it exceeds 15% of the thickness of the polyurethane sheet 2, and the coagulation bath 25 is maintained at a low temperature. It has been found that the average pore diameter can be maintained at 25 μm or less until it exceeds 20% of the thickness of the polyurethane sheet 2. Therefore, it has been clarified that the polishing pad 1 of Example 1 and Example 2 can continue the polishing process for a long period of time and can improve the life of the polishing pad 1.

本発明は被研磨物の平坦性を向上させることができ長寿命の研磨布を提供するため、研磨布の製造、販売に寄与するので、産業上の利用可能性を有する。 Since the present invention can improve the flatness of an object to be polished and provides a long-life polishing cloth, and contributes to the manufacture and sale of the polishing cloth, it has industrial applicability.

本発明を適用した実施形態の研磨パッドを示す断面図である。It is sectional drawing which shows the polishing pad of embodiment to which this invention is applied. 研磨パッドの製造工程を示す工程図である。It is process drawing which shows the manufacturing process of a polishing pad. 研磨パッドのポリウレタンシートの製造に用いる成膜装置の概略構成を示す正面図である。It is a front view which shows schematic structure of the film-forming apparatus used for manufacture of the polyurethane sheet of a polishing pad. 研磨パッドの発泡の形成状態を模式的に示す説明図であり、（Ａ）は実施形態の研磨パッド、（Ｂ）は従来の研磨パッドをそれぞれ示す。It is explanatory drawing which shows typically the formation state of foaming of a polishing pad, (A) shows the polishing pad of embodiment, (B) shows the conventional polishing pad, respectively.

Explanation of symbols

１研磨パッド（研磨布）
２ポリウレタンシート（軟質プラスチックシート）
２ａスキン層
２ｂナップ層（発泡層）
３発泡（第２の発泡）
４微細発泡（第１の発泡） 1 Polishing pad (polishing cloth)
2 Polyurethane sheet (soft plastic sheet)
2a Skin layer 2b Nap layer (foamed layer)
3 Foam (second foam)
4 Fine foaming (first foaming)

Claims

In a polishing cloth provided with a soft plastic sheet that is formed by a wet film formation method, includes a skin layer, and a foam layer positioned inside the skin layer, and allows abrasion due to polishing, the foam layer includes: The first foam formed biased toward the skin layer side and the second foam whose length in the thickness direction of the foam layer is longer than the first foam are formed substantially evenly . The first and second foams have a substantially triangular cross section and communicate with each other through communication holes. The diameters of the first and second foams are reduced on the skin layer side, and An abrasive cloth having an average of 25 μm or less until the thickness exceeds at least 15% of the thickness of the soft plastic sheet in the inner direction from the skin layer.

2. The pore diameter of the first and second foams of the foam layer is an average of 25 μm or less until it exceeds at least 20% of the thickness of the soft plastic sheet in the inner direction from the skin layer. Polishing cloth as described in 2.

The total number of the first and second foams of the foam layer is 30 or more per 1 mm in the direction along the skin layer in a portion where the pore diameter of the first and second foams is 25 μm or less on average. The polishing cloth according to claim 1 or 2.

The second foam is formed substantially uniformly with a length over substantially the entire thickness direction of the foam layer, and the first foam is formed between the second foams, polishing cloth according to claim 1, characterized that you have a variation in length in the thickness direction of the foam layer.

The first and second foams of the foam layer are formed by a hydrophilic additive added to the soft plastic solution for producing the soft plastic sheet. The polishing cloth according to any one of the above.

The abrasive cloth according to claim 5, wherein the hydrophilic additive is an anionic surfactant or a nonionic surfactant.

The abrasive cloth according to claim 6 , wherein the soft plastic sheet is formed by applying the soft plastic solution to a flexible film that is impermeable to liquid .

On the opposite side of the skin layer of the soft plastic sheet, at least one kind selected from a flexible film, a non-woven fabric, and a woven fabric, and further comprising a support layer that supports the soft plastic sheet. The polishing cloth according to any one of claims 1 to 7.