JP2018083282A - Polishing pad and manufacturing method thereof, and manufacturing method of object to be polished - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing pad capable of securing polishing face quality at polishing an object to be polished having a curved surface and a manufacturing method thereof, and a manufacturing method of an object to be polished using the polishing pad.SOLUTION: A polishing pad comprises: a substrate having a polishing surface provided with piloerection, and a connection part connecting respective one ends of the piloerection with each other; and a resin impregnated in the substrate. At least the piloerection is formed of a knitted fabric knitted with warp or weft, and derived from intermediate fibers, the knitted fabric including front and rear face fibers forming front and rear faces and the intermediate fibers which connect the front and rear face fibers, while the connection part is derived from either one of the front and rear face fibers.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polishing pad, a method for manufacturing the same, and a method for manufacturing a polished article.

  Conventionally, it is known that a buff is used for polishing an object having a flat surface and a curved surface (Patent Document 1). In Patent Document 1, a plurality of surfaces are provided on the surface of the base fabric stretched on the surface of the rotating plate with the intention of reducing the frictional resistance with the object to be polished by causing a slackening action on the polishing surface. There has been proposed a buff in which strip-shaped polishing cloths are arranged radially from the center of the rotating plate with appropriate intervals.

Japanese Patent Laid-Open No. 10-15835

  However, the buff lacks the ability to follow the surface of the object to be polished, and in order to polish flat and curved surfaces, it is necessary to polish while changing the contact position and angle, which makes the polishing process complicated and problematic from the viewpoint of cost. There is. Also, a polishing pad in which a sponge or non-woven fabric is impregnated with a resin instead of a buff and a groove is formed on the polishing surface for conformability to a curved surface is used to polish an object having a flat surface and a curved surface. It is also possible to use it. However, a polishing pad that is simply formed with a groove to improve followability to a curved surface has a problem that a polishing mark derived from the groove is easily generated on the surface of the object to be polished. In addition, when the polishing pad having such grooves is bent to follow the workpiece, a load is applied to the land portion sandwiched between the grooves, particularly in the vicinity of the groove, and the land portion is damaged or dropped off. As a result, scratches such as scratches can be caused on the object to be polished. Further, when a non-woven fabric is used, there is a risk that scratches or the like may be caused on the object to be polished by dropping off the fibers.

  Therefore, those of glass and metal housings that have a flat surface and a curved surface and also have side surfaces (a surface that faces in a different direction from the flat surface and is usually connected to the flat surface via a curved surface). This is a polishing pad that can polish not only flat surfaces but also curved surfaces and side surfaces using a surface polishing machine when mirror-polishing the surface of the surface. There is a need for polishing pads that do not.

  The present invention has been made in view of the above circumstances, and it is possible to polish not only a flat surface of an object to be polished but also a curved surface and a side surface using a flat polishing machine, and ensuring a polished surface quality. It is an object of the present invention to provide a polishing pad that can be used, a method for manufacturing the same, and a method for manufacturing a polished article using the polishing pad.

  The present inventors diligently studied to solve the above problems. As a result, the present invention finds that the above problem can be solved if the polishing pad is provided with a base material in which napped surfaces are formed by removing the surface of the knitted fabric and the base material is impregnated with resin. It came to complete.

That is, the present invention is as follows.
[1]
A base material having a polishing surface on which nappings are arranged and a connecting portion that connects one end of the nappings;
A resin impregnated in the base material,
At least the raised fibers are knitted fabrics composed of warp knitting or weft knitting, and the intermediate fibers among the knitted fabrics having front and back fibers forming the front and back surfaces and intermediate fibers connecting the front and back surfaces. Is derived from
The connecting portion is derived from either one of the front and back fibers.
Polishing pad.
[2]
The average length of the raised hair is 0.5 to 20 mm,
The polishing pad according to [1].
[3]
The nap is a raw thread,
The polishing pad according to [1] or [2].
[4]
The resin includes a polycarbonate-based polyurethane resin,
The polishing pad according to any one of [1] to [3].
[5]
The Shore A hardness of the base material impregnated with the resin is 0 to 30 °.
The polishing pad according to any one of [1] to [4].
[6]
The compression modulus of the base material impregnated with the resin is 50 to 98%;
The polishing pad according to any one of [1] to [5].
[7]
The number average diameter of the single yarn constituting the knitted fabric is 3 to 500 μm,
The polishing pad according to any one of [1] to [6].
[8]
The amount of compressive deformation of the base material impregnated with the resin is 0.5 to 15 mm,
The polishing pad according to any one of [1] to [7].
[9]
The thickness of the base material impregnated with the resin is 1.0 to 22 mm,
The polishing pad according to any one of [1] to [8].
[10]
A cushion layer is further provided on the opposite side of the substrate from the polishing surface.
The polishing pad according to any one of [1] to [9].
[11]
The cushion layer has a thickness of 3 to 25 mm.
[10] The polishing pad according to [10].
[12]
The Shore A hardness of the cushion layer is 0 to 0.3 ° or less,
The polishing pad according to [10] or [11].
[13]
The amount of compressive deformation of the cushion layer is 2.0 to 20 mm.
[10] The polishing pad according to any one of [12].
[14]
The compression elastic modulus of the cushion layer is 85 to 99%.
[10] The polishing pad according to any one of [13].
[15]
The cushion layer has a density of 0.010 to 0.100 g / cm ³ .
[10] The polishing pad according to any one of [14].
[16]
Impregnation step of obtaining a resin-impregnated knitted fabric by impregnating a knitted fabric composed of warp knitting or weft knitting with a resin solution containing a resin and performing wet coagulation;
A surface removal step of exposing intermediate fibers connecting the front and back surfaces of the knitted fabric as napped by removing the resin and fibers present on either the front or back surface of the resin-impregnated knitted fabric,
Manufacturing method of polishing pad.
[17]
Before the surface removal step, the immersion step of immersing the resin-impregnated knitted fabric in an immersion liquid containing a solvent in which the resin is soluble,
[16] The method for producing a polishing pad according to [16].
[18]
The polishing pad according to [16] or [17], wherein the resin is soluble in at least one selected from the group consisting of N, N-dimethylformaldehyde, N, N-dimethylacetamide, methyl ethyl ketone, and dimethyl sulfoxide. Production method.
[19]
Any of [16] to [18], wherein the solvent in which the resin is soluble includes at least one solvent selected from the group consisting of N, N-dimethylformaldehyde, N, N-dimethylacetamide, methyl ethyl ketone, and dimethyl sulfoxide. A method for producing a polishing pad according to claim 1.
[20]
Using the polishing pad according to any one of [1] to [15], the method includes a polishing step of polishing an object to be polished.
A method for producing an abrasive.

  According to the present invention, a polishing pad capable of polishing not only the flat surface of the object to be polished, but also the curved surface and side surfaces, and a method for producing the same can be secured by using a flat polishing machine. In addition, it is possible to provide a method for producing a polished article using a polishing pad.

It is a conceptual diagram which shows the surface removal process in the manufacturing method of the polishing pad of this embodiment. It is a conceptual diagram which shows the carrier used in the grinding | polishing test of the Example. It is a conceptual diagram for demonstrating the grinding | polishing test of an Example. It is sectional drawing of the nonwoven fabric A used in the comparative example. 2 is a photograph of the surface (curved surface) of an object to be polished before the polishing test of Example 1; 2 is a photograph of the surface (curved surface) of an object to be polished after the polishing test of Example 1.

  Hereinafter, a form for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail with reference to the drawings as necessary. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

[Polishing pad]
The polishing pad of this embodiment includes a base material having a polishing surface on which napped hairs are arranged and a connecting portion that connects one end of the napped hairs, and a resin impregnated in the base material. Is a knitted fabric composed of warp knitting or weft knitting, and is derived from the intermediate fibers among the knitted fabrics having front and back fibers forming the front and back surfaces and intermediate fibers connecting the front and back surfaces. And the connecting portion is derived from one of the front and back fibers.

  That is, the base material of the polishing pad of the present embodiment is a knitted fabric composed of warp knitting or weft knitting, and includes a knitted fabric having front and back fibers forming the front and back surfaces and intermediate fibers connecting the front and back surfaces. By removing either one of the front and back surfaces by buffing or cutting, a base material having a polished surface on which nappings are arranged and a connecting portion that connects one end of the nappings is used. As described above, by providing either one of the front and back surfaces of the knitted fabric composed of warp knitting or weft knitting in a state of being cut in the surface direction, napped fibers can be formed and the fiber end surfaces of the napped fibers are uniform. It is possible to form a polished surface in which the fiber is prevented from being detached. Therefore, when polishing with a flat polishing machine using the polishing pad of this embodiment, it is possible to polish not only the flat surface but also the curved surface of the object to be polished and the side surface facing the direction different from the flat surface. (High followability) and the quality of the polished surface can be secured, and the polishing rate is also excellent.

  The resin is impregnated in the base material, and impregnated and adhered to the inside and the surface of the fibers constituting the napped and the connecting portion. However, voids exist between the nappings due to the impregnation and adhesion of the resin. By using such a resin, it is possible to reinforce the strength of the napping and the connecting portion and improve the polishing rate and the surface quality of the object to be polished without impairing the followability of the polishing pad to the object to be polished.

〔Base material〕
The amount of compressive deformation of the base material impregnated with the resin (that is, the composite of the resin and the base material impregnated with the resin; the same applies hereinafter) is preferably 0.5 to 15 mm, more preferably 1. It is 0-15 mm, More preferably, it is 1.0-10 mm, More preferably, it is 1.0-5.0 mm, Most preferably, it is 1.0-3.0 mm. When the amount of compressive deformation is 0.5 mm or more, the followability and the surface quality of the object to be polished tend to be further improved. Moreover, it exists in the tendency which can improve a polishing rate more and can suppress a deformation | transformation of a polishing pad more because it is 15 mm or less. The amount of compressive deformation can be measured by the method described in the examples. Further, the amount of compressive deformation can be adjusted, for example, depending on the length of napping and the type of resin selected.

  The average length of napping is preferably 0.5 to 20 mm, more preferably 1.0 to 15 mm, still more preferably 1.5 to 10 mm, and even more preferably 1.5 to 5.0 mm. And more preferably 1.5 to 3.0 mm. When the average length of the napped is 0.5 mm or more, the adhesion to the object to be polished is further improved, and the followability to the object to be polished having a curved surface tends to be further improved. In addition, when the average length of the napped is 20 mm or less, a brush with a harder napped is formed, and thus the polishing rate tends to be further improved. In addition, the average length of napping means the average value of the length (full length) of napping rising from a connection part (refer FIG. 1).

  The compression modulus of the base material impregnated with the resin is preferably 50 to 98%, more preferably 60 to 98%, still more preferably 70 to 98%, and even more preferably 80 to 98%. And particularly preferably 90 to 98%. When the compression modulus is 50% or more, the polishing rate tends to be further improved. Further, when the compression elastic modulus is 98% or less, the adhesion to the object to be polished is further improved, and the followability to the object to be polished having a curved surface tends to be further improved. The compression modulus can be measured by the method described in the examples. Further, the compression modulus can be adjusted, for example, according to the type of resin selected in a preferable manufacturing method described later.

  The Shore A hardness of the substrate impregnated with the resin is preferably 0 to 30 °, more preferably 0 to 25 °, and still more preferably 0 to 20 °. When the Shore A hardness is 0 ° or more (above the detection limit), the polishing rate tends to be further improved. Moreover, when Shore A hardness is 30 degrees or less, it exists in the tendency for adhesiveness with to-be-polished material to improve, and to follow to the to-be-polished object which has a curved surface more. In addition, Shore A hardness can be measured by the method as described in an Example. Moreover, Shore A hardness can be adjusted with the kind of resin to select, for example.

Density of the resin impregnated substrate is preferably 0.10 to 0.40 g / cm ^3, more preferably from 0.15~0.35g / cm ^3, more preferably 0.15 to 0 .30 g / cm ³ . When the density is 0.10 g / cm ³ or more, the permanent distortion of the polishing pad tends to be further suppressed. Moreover, when the density is 0.40 g / cm ³ or less, the followability tends to be further improved. In addition, a density can be measured by the method as described in an Example. Moreover, a density can be adjusted with the content rate of resin with respect to a knitted fabric in the preferable manufacturing method mentioned later, for example.

  The thickness of the base material impregnated with the resin is preferably 1.0 to 22 mm, more preferably 1.5 to 20 mm, still more preferably 2.0 to 15 mm, and even more preferably 10 mm. Yes, particularly preferably 5 mm. When the thickness is 1.0 mm or more, the followability to the object to be polished tends to be further improved. In addition, when the thickness is 22 mm or less, the deformation (swell or surface shape) of the object to be polished tends to be more stable and improved. In addition, thickness can be measured by the method as described in an Example. The thickness can be adjusted by, for example, how to knit the knitted fabric or the amount of the front and back layers to be removed.

[Knitted fabric]
The knitted fabric is constituted by warp knitting or weft knitting, and has front and back fibers forming the front and back surfaces and intermediate fibers connecting the front and back surfaces. Compared to nonwoven fabrics, knitted fabrics composed of warp knitting or weft knitting have a regular knitting structure, so the distribution of fiber end faces on the polished surface is more uniform, and the uniformity of the polishing rate is further improved over the entire polished surface. To do. Further, the regular distribution of the fiber end faces enables more uniform polishing, and can contribute to achieving polishing with excellent surface quality. Furthermore, by using any one of the front and back surfaces of the knitted fabric as a connecting portion, it is possible to suppress the napping of the polished surface from falling off during polishing. Thereby, it is possible to suppress the occurrence of scratches on the surface of the object to be polished due to the napped hairs that have fallen off. In addition, warp knitting is preferable from the viewpoint of obtaining longer napping.

  The polishing pad of this embodiment can be used for both polishing and lapping, but is preferably used for primary polishing and / or secondary polishing. In particular, by changing the knitting method of the knitted fabric, it is possible to easily configure a polishing pad according to the required polishing rate and surface quality.

  The warp knitting is not particularly limited, and examples thereof include tricots such as single tricot and double tricot; raschels such as single raschel and double raschel; and Miranese. Among the warp knitting, Russell is preferable from the viewpoint of more effectively exerting the effects of the present invention.

  The weft knitting is not particularly limited, and examples thereof include round knitting such as single knitting and double knitting; and flat knitting such as rib knitting, double-side knitting and double-head knitting. Further, the single knitting is not particularly limited, and examples thereof include a sinker table round knitting, a hanging knitting, and a tompkin knitting. The double knitting is not particularly limited, and examples thereof include a milling knitting, a smooth knitting, and a cardboard knitting. Among the weft knitting, a circular knitting is preferable and a corrugated cardboard knitting is more preferable from the viewpoint of more effectively exerting the effects of the present invention.

  Further, the fibers constituting the knitted fabric are not particularly limited. For example, polyester fibers such as polyethylene terephthalate, polybutylene terephthalate, and polylactic acid; polyamides such as nylon 6, nylon 66, nylon 11, nylon 12, and nylon 610 -Based fibers; polyolefin fibers such as polyethylene and polypropylene are listed. Of these, polyester fibers are preferred.

  It is preferable that the intermediate fiber constituting the knitted fabric is a raw yarn not subjected to false twisting or the like. Thereby, the napping of the polishing pad according to the present embodiment becomes a raw thread. By using the raw yarn, the followability of the napping is further improved and the polishing rate tends to be improved as compared with the false twisted yarn. In addition, the front and back fibers constituting the front and back surfaces of the knitted fabric may be raw yarns or false twisted yarns.

  Further, the front and back fibers constituting the front and back surfaces of the knitted fabric and the intermediate fibers connecting the front and back surfaces of the knitted fabric may be the same or different from each other. The type of fiber that mainly constitutes the knitted fabric front and back and the type of fiber that mainly constitutes the inner structure of the knitted fabric can be appropriately adjusted by selecting the knitting method and the fiber. For example, as described above, the polishing rate tends to be further improved by using the raw yarn as the fiber mainly constituting the inner structure of the knitted fabric. Further, the intermediate fiber connecting the front and back surfaces of the knitted fabric may be one type of fiber or two or more different types of fibers, and the type of the filament may be any of multifilament, monofilament, and a combination of multifilament and monofilament.

  The number average diameter of the single yarn constituting the knitted fabric is preferably 3 to 500 μm, more preferably 5 to 300 μm, and still more preferably 10 to 200 μm. Since the number average diameter of the single yarn constituting the knitted fabric is within the above range, the followability of the napping is further improved, the polishing rate is further improved, and the strength of the connecting portion is also improved. There is a tendency for surface quality of objects to be further improved. Furthermore, when the number average diameter of the single yarn constituting the knitted fabric is within the above range, the production of the yarn or the knitted fabric tends to be easier.

  The single yarn fineness constituting the knitted fabric is preferably 0.1 to 2700 dtex, more preferably 0.5 to 1000 dtex, still more preferably 1 to 500 dtex, still more preferably 1 to 100 dtex, More preferably, it is 1-10 dtex, Most preferably, it is 1-5 dtex. When the single yarn fineness constituting the knitted fabric is within the above range, the production of the yarn or the knitted fabric tends to be easier.

  The fiber fineness constituting the knitted fabric is preferably 30 to 2700 dtex, more preferably 40 to 1000 dtex, and still more preferably 50 to 500 dtex. When the fiber fineness which comprises a knitted fabric exists in the said range, it exists in the tendency for manufacture of a thread | yarn or a knitted fabric to become easier. Here, “fiber” refers to a multifilament in which a single yarn (monofilament) is assembled into a plurality of filaments and a monofilament when used as a single yarn.

  The number of filaments per fiber constituting the knitted fabric is preferably 1 to 100, preferably 1 to 80, preferably 1 to 60, even more preferably 5 to 60, and still more preferably. 10-50. When the number of filaments per fiber is within the above range, the production of yarn and knitted fabric tends to be easier.

〔resin〕
The resin impregnated in the base material is not particularly limited, but for example, polyurethane resins such as polyurethane and polyurethane polyurea; acrylic resins such as polyacrylate and polyacrylonitrile; polyvinyl chloride, polyvinyl acetate, polyvinylidene fluoride, and the like Vinyl sulfone resins; polysulfone resins such as polysulfone and polyethersulfone; acylated cellulose resins such as acetylated cellulose and butyryl cellulose; polyamide resins; and polystyrene resins. Among these, it is preferable that a polyurethane resin is included as the resin impregnated in the base material. Examples of the polyurethane resin include, but are not limited to, a polyester polyurethane resin, a polyether polyurethane resin, and a polycarbonate polyurethane resin, and a polycarbonate polyurethane resin is more preferable. By using such a resin, the balance between the hardness and softness of napping is further improved, and as a result, the balance between the improvement of the polishing rate and the followability to the object to be polished having a curved surface tends to be further improved. The resin impregnated in the substrate may be used alone or in combination of two or more.

  Moreover, as said resin, what can impregnate a base material with what is called wet solidification resin is preferable. Examples of such resins include, but are not limited to, polyurethane resins, acrylic resins, vinyl resins, polysulfone resins, acylated cellulose resins, polyamide resins, and polystyrene resins. Examples of polyurethane resins include, but are not limited to, polyester polyurethane resins, polyether polyurethane resins, and polycarbonate polyurethane resins. The “wet coagulation” means impregnating a resin solution in which a resin is dissolved into a knitted fabric and immersing it in a bath of a coagulation liquid (which is a poor solvent for the resin), thereby impregnating the resin solution. The resin inside is solidified and regenerated. By replacing the solvent and the coagulation liquid in the resin solution, the resin in the resin solution is aggregated and coagulated. From the viewpoint of wet coagulation, the resin is preferably soluble in at least one selected from the group consisting of N, N-dimethylformaldehyde, dimethylacetamide, methyl ethyl ketone, and dimethyl sulfoxide.

  The 100% modulus of the resin at 23 ± 2 ° C. is preferably 1 MPa to 30 MPa, more preferably 2 MPa to 20 MPa. The 100% modulus is a value obtained by dividing the load applied by the unit area when the resin sheet is stretched 100%, that is, when the sheet is stretched twice the original length.

  The mass ratio of the knitted fabric that is the base material is preferably 30 to 60% by mass, and more preferably 30 to 55% by mass with respect to the total amount of the base material and the resin. When the mass ratio of the knitted fabric is within the above range, the polishing rate tends to be further improved.

  In addition, each content of a base material and resin can be calculated | required from the mass of the component to elute, or the mass of a residue using the difference in the solubility (polarity) to a polar solvent, or the difference in amine decomposability. . Further, the density of the polishing pad after the primary impregnation step described later can be measured and calculated from the density difference. The density can be measured in the same manner as described above.

[Other ingredients]
In addition to the knitted fabric and resin described above, the polishing pad may contain various additives that can be included in a normal polishing pad depending on the purpose. Such additives include, but are not limited to, pigments or fillers such as carbon black, hydrophilic additives, and hydrophobic additives.

  The hydrophilic additive is not particularly limited. For example, anionic surfactants such as sodium lauryl sulfate, carboxylate, sulfonate, sulfate ester salt, phosphate ester salt; hydrophilic ester compound, ether type Nonionic surfactants such as compounds, ester / ether compounds, and amide compounds are exemplified.

  In addition, the hydrophobic additive is not particularly limited. For example, polyoxyethylene alkyl ether, polyoxypropylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, perfluoroalkylethylene oxide adduct, glycerin fatty acid ester, propylene Nonionic surfactants to which an alkyl chain having 3 or more carbon atoms, such as glycol fatty acid ester, is added.

  Furthermore, various materials such as additives used in the manufacturing process may remain on the polishing pad.

[Cushion layer]
The polishing pad of this embodiment may further have a cushion layer on the side opposite to the polishing surface of the substrate. By having the cushion layer, the followability to a polished object having a curved surface is further improved, and the uniformity of the polishing pressure on the polished object tends to be further improved. Here, the followability imparted by the cushion layer means that the nappings of the polishing pad follow the flat and curved surfaces of the object to be polished, and the base material itself that is the connecting portion of the nappings is polished by the contribution of the cushion layer. It also includes flexibly following the curved surface shape of the workpiece by pressure. In other words, the cushion layer improves the followability of the base material itself, which is a napping portion, thereby providing a base material having a ground surface on which napping is arranged and a connecting portion that connects one end of the napping portion, and the base. This contributes to more effectively exerting the effect of a polishing layer (also simply referred to as “polishing layer”) comprising a resin impregnated in the material.

  The thinner the cushion layer, the higher the polishing pressure is required to make the polishing pad follow the polishing object having a curved surface. However, the improvement of the polishing pressure is not limited to scratches (grooves) and other polishing marks. This affects the direction in which the quality (for example, the boundary lines and the degree of minute defects generated on the curved surface) is reduced. On the other hand, when the cushion layer is thick and has a certain level of cushioning property, the polishing pad tends to follow the object to be polished having a curved surface even if the polishing pressure is low. As a result, it is possible to obtain an object to be polished in which boundary lines and minute defects generated on the curved surface are suppressed, and the quality of the object to be polished is further improved. In particular, when the cushion layer has a certain level or more of cushioning properties, it becomes possible to obtain an object to be polished in which boundary lines and minute defects generated on the curved surface are suppressed to such an extent that finish polishing is not required. It is possible to provide an optional polishing pad.

  Although it does not restrict | limit especially as a cushion layer, For example, a polyolefin-type foam, a polyurethane-type foam, a polystyrene-type foam, a phenol-type foam, a synthetic rubber-type foam, a silicone rubber-type foam etc. are mentioned.

  The thickness of the cushion layer is appropriately selected according to the shape and size of the object to be polished, but is preferably 3 to 25 mm, more preferably 5 to 23 mm in consideration of workability during production and use. More preferably, it is 10-23 mm, Most preferably, it is 12-20 mm. When the thickness of the cushion layer is 3 mm or more, the surface quality of the obtained workpiece tends to be further improved. In particular, by being 12 mm or more, the followability to the object to be polished is further improved, and the surface quality is further improved to the extent that the finish polishing can be omitted in that the boundary line or the like is less likely to occur in the object to be polished. It tends to improve. Moreover, when the thickness of the cushion layer is 25 mm or less, the deformation (swell or surface shape) of the object to be polished is more stable, and the installation on the polishing machine tends to be easy. In addition, thickness can be measured by the method as described in an Example.

  The Shore A hardness of the cushion layer is appropriately selected depending on the shape and size of the object to be polished, but is preferably 0 to 20 °, more preferably 0 to 5 in consideration of workability during production and use. °, more preferably 0 to 2 °, even more preferably 0 to 0.7 °, and particularly preferably 0 to 0.3 °. When the Shore A hardness is 4 ° or less, the adhesion to the object to be polished is further improved, and the followability to the object to be polished having a curved surface tends to be further improved. In particular, when the Shore A hardness is 0.3 ° or less, the follow-up to the object to be polished is further improved, and the finish polishing can be omitted in that the boundary line is less likely to occur in the object to be polished. The surface quality tends to be further improved. The lower limit of Shore A hardness is not particularly limited, but can be 0 ° (detection limit). In addition, Shore A hardness can be measured by the method as described in an Example. Moreover, Shore A hardness can be adjusted with the kind and foaming magnification of the foam to select, for example.

  The amount of compressive deformation of the cushion layer is appropriately selected depending on the shape and size of the object to be polished, but is preferably 2.0 to 20 mm, more preferably 5. It is 0-20 mm, More preferably, it is 6.0-20 mm, More preferably, it is 11-16 mm, Most preferably, it is 13-16 mm. When the amount of compressive deformation is 3.0 mm or more, the followability and the surface quality of the object to be polished tend to be further improved. In particular, when the amount of compressive deformation is 11 mm or more, the followability to the object to be polished is further improved, and finish polishing can be omitted in that the boundary line is less likely to occur in the object to be polished. The surface quality tends to be further improved. Further, when the amount of compressive deformation is 20 mm or less, the polishing rate is further improved, and deformation of the polishing pad tends to be further suppressed. The amount of compressive deformation can be measured by the method described in the examples. The amount of compressive deformation can be adjusted, for example, according to the type of foam selected and the expansion ratio.

  The compression elastic modulus of the cushion layer is appropriately selected according to the shape and size of the object to be polished, but is preferably 70 to 99%, more preferably 80 to 99, considering workability during production and use. %, More preferably 85 to 99%, still more preferably 90 to 98%, and particularly preferably 92 to 98%. When the compression modulus is 70% or more, the polishing rate tends to be further improved. In particular, when the compressive elastic modulus is 90% or more, the followability to the object to be polished is further improved, and a boundary line or the like is less likely to occur in the object to be polished, and the surface quality tends to be further improved. . Further, when the compression elastic modulus is 99% or less, the adhesion to the object to be polished is further improved, and the followability to the object to be polished having a curved surface tends to be further improved. The compression modulus can be measured by the method described in the examples. The compression elastic modulus can be adjusted by, for example, the type of resin to be selected, the type of foam, and the expansion ratio.

The density of the cushion layer is appropriately selected depending on the shape and size of the object to be polished, but is preferably 0.010 to 0.100 g / cm ³ , more preferably in consideration of workability during production or use. Is 0.020 to 0.090 g / cm ³ , more preferably 0.030 to 0.080 g / cm ³ . When the density is 0.010 g / cm ³ or more, the permanent distortion of the polishing pad tends to be further suppressed. Moreover, when the density is 0.100 g / cm ³ or less, the followability tends to be further improved. In addition, a density can be measured by the method as described in an Example. The density can be adjusted by, for example, the type of resin to be selected, the type of foam, and the expansion ratio.

[Production method of polishing pad]
The manufacturing method of the polishing pad of this embodiment forms a napped by impregnating a resin into a knitted fabric and solidifying it, and removing the resin and fibers present on either the front or back of the knitted fabric If it is a method which has a process to do, it will not specifically limit. For example, when a plurality of types of resins are used, a plurality of resins may be mixed and impregnated into the knitted fabric at once, or after a part of the resin is impregnated into the knitted fabric and solidified, the remaining resin You may have the multistage impregnation process which makes a knitted fabric impregnate and solidify. In addition, regarding the timing of removal (cutting) of the resin and fibers present on either the front or back side of the knitted fabric, the resin and fibers present on either the front or back side of the knitted fabric after impregnation with the resin are removed. It may be cut (cut), or after impregnating a part of the resin, either the resin or the fiber on the front or back surface of the knitted fabric may be removed, and the remaining resin may be further impregnated.

  As a method for manufacturing the polishing pad of the present embodiment, for example, an impregnation step of obtaining a resin-impregnated knitted fabric by impregnating a knitted fabric composed of warp knitting or weft knitting with a resin solution containing a resin and performing wet coagulation; And a surface removal step of exposing the intermediate fibers connecting the front and back surfaces of the knitted fabric as napped by removing the resin and fibers present on either the front or back surface of the resin-impregnated knitted fabric. Can be mentioned.

[Impregnation process]
The impregnation step is a step of obtaining a resin-impregnated knitted fabric by impregnating a knitted fabric constituted by warp knitting or weft knitting with a resin solution containing a resin and performing wet coagulation. When the wet coagulation method is used after impregnating the knitted fabric with the resin solution, in the coagulating liquid, the substitution of the resin solution solvent and the coagulating liquid on the surface of the resin solution adhering to the knitted fabric fibers proceeds. The resin is coagulated and regenerated on the fiber surface.

  Specific examples of the impregnation step are as follows. First, a resin suitable for wet coagulation as described above, a solvent capable of dissolving the resin and mixed with the coagulation liquid described below, and other additives as necessary are mixed, and further if necessary. And defoaming under reduced pressure to prepare a resin solution. The solvent is not particularly limited, and examples thereof include N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAC), methyl ethyl ketone (MEK), and dimethyl sulfoxide. From the viewpoint of selecting a good solvent for the resin, and from the viewpoint of facilitating wet coagulation by uniformly mixing with the coagulation bath, the resin is composed of N, N-dimethylformaldehyde, N, N-dimethylacetamide, methyl ethyl ketone and dimethyl. It is preferably soluble in one or more solvents selected from the group consisting of sulfoxides. Similarly, the solvent preferably contains one or more solvents selected from the group consisting of N, N-dimethylformaldehyde, N, N-dimethylacetamide, methyl ethyl ketone and dimethyl sulfoxide.

  From the viewpoint of impregnating the resin over the entire knitted fabric, and from the viewpoint of sufficiently ensuring the impregnation amount of the resin, the viscosity measured at 20 ° C. using a B-type rotational viscometer for the resin solution is preferably It is 8000 cp or less, More preferably, it is 100 cp-5000 cp, More preferably, it is 400 cp-3000 cp. From the viewpoint of obtaining a resin solution having such a numerical range of viscosity, for example, the polyurethane resin is a solvent in a range of 5 to 25% by mass, more preferably in a range of 8 to 20% by mass with respect to the total amount of the resin solution. It may be dissolved in Since the viscosity of the resin solution also depends on the type and molecular weight of the resin to be used, it is preferable to select the resin, set the concentration, etc. in consideration of these comprehensively.

  Next, after sufficiently immersing the knitted fabric in the resin solution, the resin solution is squeezed out from the knitted fabric to which the resin solution has adhered using a mangle roller that can be pressurized between a pair of rollers. The amount of adhesion to the knitted fabric is adjusted to a desired amount and the knitted fabric is impregnated with the resin solution uniformly or substantially uniformly. Next, the knitted fabric impregnated with the resin solution is immersed in a coagulant containing a poor solvent for the resin, for example, water as a main component, so that the resin (hereinafter, the resin that is wet coagulated is referred to as “wet resin”). Coagulate and regenerate. In order to adjust the regeneration speed of the resin, an organic solvent such as a polar solvent other than the solvent in the resin solution may be added to the coagulation liquid. The temperature of the coagulation liquid is not particularly limited as long as the resin can be coagulated, and may be, for example, 15 to 60 ° C.

  In this embodiment, after performing the above-mentioned wet coagulation, it is preferable to use the following washing / drying steps. First, the knitted fabric obtained by coagulating and regenerating the wet resin is washed in a cleaning solution such as water, and the solvent such as DMF remaining in the resin-impregnated knitted fabric is removed. After washing, the knitted fabric is pulled up from the washing liquid, and excess washing liquid is squeezed out using a mangle roller or the like. Thereafter, the knitted fabric substrate may be dried in a dryer at 100 ° C to 150 ° C. In addition, after the above drying, the obtained resin-impregnated knitted fabric is further subjected to processing by slicing, buffing, etc., and the skin layer of the surface layer is removed to a predetermined thickness, so that the uniformity of the dipping step in the next step is improved. It is preferable from the viewpoint of enhancing.

[Immersion process]
The manufacturing method of the polishing pad of this embodiment may have a dipping process of dipping the resin-impregnated knitted fabric in a dipping solution containing a solvent in which the resin is soluble before the surface removing process described later. The dipping process is a process in which the wet resin is partially re-dissolved in the solvent by dipping the resin-impregnated knitted fabric in a dipping solution containing a solvent in which the resin is soluble. It is considered that air bubbles (for example, closed pores and open pores having small openings) inside the resin-impregnated knitted fabric are reduced by the dipping process, and adhesion between the knitted fabric and the wet resin is improved. Although it does not specifically limit as a solvent used for an immersion process, For example, N, N- dimethylformamide (DMF), N, N- dimethylacetamide (DMAC), methyl ethyl ketone (MEK), and dimethyl sulfoxide (DMSO) are mentioned. Moreover, as temperature conditions at the time of immersion, it is preferable that it is 15.0-25.0 degreeC from a viewpoint of reducing the bubble of resin and preventing the elution of the resin to a solvent, As immersion time, From the same viewpoint, it is preferably 5 to 30 seconds. In addition, it is preferable to provide a drying process after the above-mentioned immersion process.

[Surface removal process]
The surface removal step is a step of exposing the intermediate fibers connecting the front and back surfaces of the knitted fabric as napped by removing the resin and fibers present on either the front or back surface of the resin-impregnated knitted fabric. By the surface removal step, a cross section cut in the surface direction of the knitted fabric can be formed as the polishing surface. In FIG. 1, the conceptual diagram of a surface removal process is shown. FIG. 1 is a cross-sectional view of the resin-impregnated knitted fabric 1 after the dipping process when a resin (not shown) and front and back fibers 2 existing on the front and back surfaces are removed. As shown in FIG. 1, in this embodiment, one of the front and back fibers 2 of the knitted fabric 1 having front and back fibers 2 that form the front and back surfaces and intermediate fibers 3 that connect the front and back surfaces is removed together with the resin. Thus, the polished surface 4 having the raised hairs 5 is produced. At this time, the other of the front and back fibers becomes the connecting portion 6, and the polished surface 4 has the end surfaces of the napped portions 5 uniformly distributed in the surface direction.

  The method for removing the fibers and the resin from the resin-impregnated knitted fabric is not particularly limited, and a method of cutting the intermediate fiber 3 and its surrounding resin using a band knife or the like, a surface fiber and a resin by buffing, etc. The method of removing is mentioned.

  The polishing pad obtained as described above may then be cut into a desired shape and size such as a circle as necessary, and inspection such as confirming that there is no dirt or foreign matter attached. May be applied.

[Cushion layer forming process]
The manufacturing method of the polishing pad of this embodiment may include a cushion layer forming step of forming a cushion layer on the surface of the polishing pad opposite to the polishing surface. The method for forming the cushion layer is not particularly limited, and a method of sticking the resin foam to the surface opposite to the polishing surface of the polishing pad via an adhesive layer can be employed. Also, a double-sided tape (adhesive layer and release paper for attaching the polishing pad to the polishing surface plate of the polishing machine via the cushion layer on the surface opposite to the surface on which the polishing pad of the cushion layer is bonded is provided. May be pasted together.

[Production Method of Polished Product]
The manufacturing method of the polishing object of this embodiment will not be specifically limited if it is a method which has the grinding | polishing process of grind | polishing a to-be-polished object using the said polishing pad. The polishing step may be primary polishing (rough polishing), secondary polishing (finish polishing), or may be a combination of both polishings.

  Although it does not specifically limit as a to-be-polished object, For example, the to-be-polished object which has planes, side surfaces, a curved surface, etc., such as metals, such as a portable electronic device housing | casing and accessories, glass, such as sapphire glass, resin.

  As a polishing method, a conventionally known method can be used and is not particularly limited. 2 to 3 illustrate a polishing method performed in a polishing test in Examples described later. In the method for manufacturing a polished article of the present embodiment, as shown in FIG. 2, the workpiece W is placed on the stage S of the carrier C, and the polishing surface of the polishing pad is brought into contact with the object to be polished as shown in FIG. Polishing can be performed on the polished object. The nappings constituting the polishing surface of the polishing pad follow not only the flat surface (upper surface) of the object to be polished, but also the curved surface connecting the flat surface and the side surface and the side surface facing the direction different from the flat surface. Thereby, according to the polishing pad of this embodiment, it becomes possible to abbreviate | omit the grinding | polishing process for grind | polishing a curved surface and a side surface again, and can improve the throughput of the whole grinding | polishing process.

  Further, as shown in FIG. 2, in addition to an embodiment in which the polishing surface of the polishing pad is brought into contact with the object to be polished from above the object to be polished, the polishing surface of the polishing pad is viewed from below the object to be polished. It is also possible to adopt a mode in which polishing is performed on an object to be polished by contacting the object to be polished, or a so-called double-sided polishing mode in which polishing is performed by bringing the polishing surface of the polishing pad into contact with the polishing object simultaneously from above and below the object to be polished.

  Hereinafter, a method for polishing an object to be polished with a polishing pad in the presence of abrasive grains will be described as an example. First, a polishing pad is mounted and fixed on a polishing surface plate of a polishing machine. Then, the polishing surface plate is pressed while the object to be polished held on the holding surface plate disposed so as to face the polishing surface plate is pressed to the polishing surface side of the polishing pad, and slurry is supplied between the workpiece and the polishing pad. In addition, the processing surface of the workpiece is polished by relatively rotating the holding surface plate.

  The slurry may contain a strong oxidizing agent, a solvent, and abrasive particles (abrasive grains) used in chemical mechanical polishing. Although it does not specifically limit as a strong oxidizing agent, For example, potassium permanganate, sodium permanganate, etc. are mentioned. Examples of the solvent include water and organic solvents. As the organic solvent, a hydrocarbon is preferable, and a hydrocarbon having a high boiling point is more preferable. The hydrocarbon is not particularly limited, and examples thereof include paraffinic hydrocarbons, olefinic hydrocarbons, aromatic hydrocarbons, and alicyclic hydrocarbons. Examples of the hydrocarbon having a high boiling point include petroleum hydrocarbons having an initial boiling point of 220 ° C. or higher. A solvent is used individually by 1 type or in combination of 2 or more types.

  The slurry may contain other additives as necessary. Examples of such additives include nonionic surfactants, anionic surfactants, carboxylic acid esters, carboxylic acid amides, and carboxylic acids.

  In the method for producing a polished article according to the present embodiment, secondary polishing (finish polishing) is performed after primary polishing (rough polishing) in order to reduce boundary lines and minute defects generated by primary polishing (rough polishing). You may go. However, as described above, when a polishing pad having a cushioning property of a certain level or more is used, boundary polishing and minute defects are less likely to occur in rough polishing, so that the final polishing step can be omitted. Therefore, according to the polishing pad and the method for manufacturing a polished product of the present embodiment, the plane and the curved surface of the object to be polished can be simultaneously polished. Therefore, the plane and the curved surface of the object to be polished are performed in separate polishing steps. In addition to being able to simplify the polishing process in that it is not necessary, it is also possible to omit the final polishing process in that rough polishing and final polishing can be achieved simultaneously. It is possible to improve the throughput in the entire manufacturing process of the polished article.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The present invention is not limited in any way by the following examples.

[Shore A hardness]
The stylus A hardness of the polishing pad was measured from the pressing depth of the pressing needle 30 seconds after the pressing needle (measurement element) was pressed against the surface of a test piece having a thickness of 4.5 mm or more via a spring. A durometer type A was used as a measuring device. This was performed three times to determine the Shore A hardness from the arithmetic average. Specifically, the polishing pad was cut out to 10 cm × 10 cm, used as a sample piece, and a plurality of sheets were stacked and measured so as to have a thickness of 4.5 mm or more.

[Compression deformation and compression modulus]
The amount of compressive deformation and the compressive elastic modulus of the polishing pad were measured according to Japanese Industrial Standard (JIS L 1021) using a shopper type thickness measuring instrument (pressurized surface: circular with a diameter of 1 cm). Specifically, the thickness t ₀ after pressing for 30 seconds with an initial load was measured, and then the thickness t ₁ after standing for 5 minutes under the final load was measured. All the loads were removed, and after standing for 1 minute, the thickness t ₀ ′ after pressing for 30 seconds with the initial load again was measured. At this time, the initial load was 100 g / cm ² and the final load was 1120 g / cm ² . The amount of compressive deformation was calculated by the following formula (1), and the compression modulus was calculated by the following formula (2).
Equation (1): amount of compressive deformation (mm) = t ₀ -t ₁
Formula (2): Compression modulus (%) = (t ₀ ′ −t ₁ ) / (t ₀ −t ₁ ) × 100

〔thickness〕
The thickness of the polishing pad was measured in accordance with Japanese Industrial Standard (JIS K 6505) using a shopper type thickness measuring instrument (pressure surface: circular shape with a diameter of 1 cm). Specifically, three sample pieces each having a polishing pad cut out to 10 cm × 10 cm were prepared, and each sample piece was set at a predetermined position of a thickness measuring device, and then a pressure surface to which a load of 480 g / cm ² was applied. The sample was placed on the surface of the sample piece, and the thickness was measured after 5 seconds. For each sample piece, the thickness was measured at five locations to calculate an arithmetic average, and an arithmetic average of three sample pieces was obtained.

〔density〕
The polishing pad was cut into 10 cm × 10 cm, used as a sample piece, the mass was measured, and the density (bulk density) (g / cm ³ ) of the polishing pad was calculated from the volume obtained from the thickness and the mass.

[Polishing test]
The polishing pad was attached to a surface plate of a polishing machine (Lap Master, 36PL-3R). Next, glass having a curved surface (size 50 mm × 100 mm × 1 mmt) was prepared as an object to be polished (work W), and placed on the stage S of the carrier C shown in FIG. The upper drawing of FIG. 2 is a plan view of the carrier C, and a cross-sectional view taken along the line AA ′ is a lower drawing. Next, as shown in FIG. 3, the polishing surface of the polishing pad was brought into contact with the object to be polished, and the object to be polished was polished under the following polishing conditions.
(Polishing conditions)
Slurry: 10% by weight cerium oxide particle aqueous dispersion Polishing time: 60 min
Polishing pressure: 170 gf / cm ²
Polishing speed: 20 rpm surface plate
: Carrier 23rpm

The surface of the polished object obtained by the above polishing test was confirmed and evaluated according to the following evaluation criteria.
(Evaluation criteria for surface quality)
A: No scratches or groove-like polishing marks. Excellent surface quality.
B: There are scratches and groove-like polishing marks. Poor surface quality.
(Evaluation criteria for the necessity of final polishing)
AAA: The boundary between the polished surface and side surface after polishing is almost undetectable, and no final polishing is required. AA: The surface is very thin and connects with the polished surface and side surface A boundary line can be confirmed and relatively simple finish polishing is required. A: A thin boundary line can be confirmed on the curved surface connecting the surface and side surface of the polished object after polishing. B: Polishing is required. The boundary line can be clearly seen on the curved surface connecting the surface and side surface of the object to be polished later, and finish polishing is required.

[Knitted fabric and non-woven fabric]
Knitted fabrics A and B composed of polyethylene terephthalate fibers (hereinafter also referred to as “PET fibers”), knitted fabrics C and nonwoven fabrics composed of polyethylene terephthalate fibers and nylon fibers (hereinafter also referred to as “Ny fibers”). A was prepared. Table 1 below shows the configuration of each knitted fabric. In warp knitting and circular knitting, the fibers constituting the knitted fabric front and back surfaces and the fibers constituting the inner structure of the knitted fabric (between the front surface and the back surface) are described separately.

  The knitted fabrics A and C are warp knitted fabrics (double raschel) having the following knitted fabric structure knitted by a double raschel machine having yarn feeders L1 to L6, and L3 and 4 constitute an intermediate structure. It is a fiber, and L1-6 are all yarns.

  The knitted fabric B is a warp knitted fabric (double raschel) having the following knitted fabric structure knitted by a double raschel machine having yarn feeders L1 to L6, and L3 and 4 are fibers constituting an intermediate structure. Therefore, multifilament and monofilament are fed respectively. Note that L1 to 6 are all yarns.

L1: 4-4-4-4 / 0-0-0-0 //
L2: 0-1-1-1 / 1-0-0-0-0 //
L3: 0-1-1-2 / 1-0-2-1 //
L4: 1-2-0-1 / 2-1-1-0 //
L5: 0-0-0-1 / 1-1-1-0 //
L6: 0-0-4-4 / 4-4-0-0 //

  Further, the cross section of the nonwoven fabric A has a trapezoidal shape having an upper base of 1.5 mm, a lower base of 4.1 mm, and a height of 3.5 mm as shown in FIG. It was assumed that they were arranged at intervals of 3 mm.

[Example 1]
(Primary impregnation step)
56.7 parts by mass of a polycarbonate-based polyurethane resin (manufactured by DIC, trade name “Chrisbon S705”) and 43.3 parts by mass of N, N-dimethylformamide were mixed to prepare a resin solution. The knitted fabric A was immersed in the obtained resin solution, and the excess resin solution was squeezed out using a mangle roller, whereby the knitted fabric A was impregnated with the resin solution substantially uniformly. Subsequently, the knitted fabric A was immersed in a coagulating liquid composed of water at 18 ° C. to solidify and regenerate the primary impregnated resin to obtain a resin-impregnated knitted fabric. Thereafter, the resin-impregnated knitted fabric was taken out from the coagulation liquid and dried to obtain a resin-impregnated knitted fabric.

(Immersion process)
Subsequently, the resin-impregnated knitted fabric obtained above was immersed in an immersion solvent in which N, N-dimethylformamide and pure water were mixed at a ratio of 65 to 35 (volume ratio). Thereafter, drying was performed to obtain a resin-impregnated knitted fabric after the dipping process.

(Surface removal process)
Thereafter, the resin-impregnated knitted fabric was dried, and napped fibers were formed by removing fibers and resin on the surface so that the upper and lower thicknesses became uniform using a buffing machine, and the surface was used as a polished surface. Finally, as a cushion layer, a polyethylene foam having a thickness of 5 mm was pasted on the side opposite to the polished surface. In addition, the average length of napping was 2.05 mm.

[Example 2]
A polishing pad of Example 2 was obtained in the same manner as in Example 1 except that knitted fabric B was used instead of knitted fabric A. In addition, the average length of the napping was 4.45 mm.

[Comparative Example 1]
In place of the knitted fabric A, the nonwoven fabric A was used, and the mangle roller nip conditions were adjusted so that the polishing pad density was 0.37 g / cm ^3. 1 polishing pad was obtained. The nonwoven fabric content was 34% by mass with respect to the entire polishing pad.

Example 3
The dipping process was not performed, and a polishing pad of Example 3 was obtained in the same manner as in Example 1 except that the knitted fabric C was used instead of the knitted fabric A. In addition, as a cushion layer, the polyurethane-type foam of thickness 10mm was affixed on the opposite side to the grinding | polishing surface. Moreover, the average length of napped was 3.02 mm

Example 4
A polishing pad of Example 4 was obtained in the same manner as in Example 3 except that a polyurethane foam having a thickness of 20 mm was used as the cushion layer.

  Table 2 shows the results of the polishing test using the obtained polishing pad together with various physical properties of the polishing pad. FIG. 5 shows a photograph of the surface (curved surface) of the polished object before the polishing test of Example 1, and FIG. 6 shows a photograph of the surface (curved surface) of the polished object after the polishing test of Example 1. In Example 1, the polishing pad showed good followability, and the raised hair could polish the side surface and the curved surface of the object to be polished, and also no polishing marks due to fiber dropping or the like were observed. On the other hand, in Comparative Example 1, although the followability of the polishing pad was recognized, polishing marks derived from scratches and grooves due to fiber dropping occurred.

  The present invention has industrial applicability as a polishing pad.

Claims (20)

A base material having a polishing surface on which nappings are arranged and a connecting portion that connects one end of the nappings;
A resin impregnated in the base material,
At least the raised fibers are knitted fabrics composed of warp knitting or weft knitting, and the intermediate fibers among the knitted fabrics having front and back fibers forming the front and back surfaces and intermediate fibers connecting the front and back surfaces. Is derived from
The connecting portion is derived from either one of the front and back fibers.
Polishing pad. The average length of the raised hair is 0.5 to 20 mm,
The polishing pad according to claim 1. The nap is a raw thread,
The polishing pad according to claim 1. The resin includes a polycarbonate-based polyurethane resin,
The polishing pad as described in any one of Claims 1-3. The Shore A hardness of the base material impregnated with the resin is 0 to 30 °.
The polishing pad as described in any one of Claims 1-4. The compression modulus of the base material impregnated with the resin is 50 to 98%;
The polishing pad as described in any one of Claims 1-5. The number average diameter of the single yarn constituting the knitted fabric is 3 to 500 μm,
The polishing pad as described in any one of Claims 1-6. The amount of compressive deformation of the base material impregnated with the resin is 0.5 to 15 mm,
The polishing pad as described in any one of Claims 1-7. The thickness of the base material impregnated with the resin is 1.0 to 22 mm,
The polishing pad as described in any one of Claims 1-8. A cushion layer is further provided on the opposite side of the substrate from the polishing surface.
The polishing pad as described in any one of Claims 1-9. The cushion layer has a thickness of 3 to 25 mm.
The polishing pad according to claim 10. The Shore A hardness of the cushion layer is 0 to 0.3 ° or less,
The polishing pad according to claim 10 or 11. The amount of compressive deformation of the cushion layer is 2.0 to 20 mm.
The polishing pad according to claim 10. The compression elastic modulus of the cushion layer is 85 to 99%.
The polishing pad according to any one of claims 10 to 13. The cushion layer has a density of 0.010 to 0.100 g / cm ³ .
The polishing pad according to claim 10. Impregnation step of obtaining a resin-impregnated knitted fabric by impregnating a knitted fabric composed of warp knitting or weft knitting with a resin solution containing a resin and performing wet coagulation;
A surface removal step of exposing intermediate fibers connecting the front and back surfaces of the knitted fabric as napped by removing the resin and fibers present on either the front or back surface of the resin-impregnated knitted fabric,
Manufacturing method of polishing pad. Before the surface removal step, the immersion step of immersing the resin-impregnated knitted fabric in an immersion liquid containing a solvent in which the resin is soluble,
The manufacturing method of the polishing pad of Claim 16.   The method for producing a polishing pad according to claim 16 or 17, wherein the resin is soluble in at least one selected from the group consisting of N, N-dimethylformaldehyde, N, N-dimethylacetamide, methyl ethyl ketone and dimethyl sulfoxide. .   The solvent in which the resin is soluble includes one or more solvents selected from the group consisting of N, N-dimethylformaldehyde, N, N-dimethylacetamide, methyl ethyl ketone, and dimethyl sulfoxide. The manufacturing method of the polishing pad of claim | item. Using the polishing pad according to any one of claims 1 to 15, a polishing step of polishing an object to be polished.
A method for producing an abrasive.