JP6480696B2 - Polishing pad, polishing pad sheet and method for producing polishing material - Google Patents

Description

  The present invention relates to a polishing pad made of a polishing material containing hollow spheres, a sheet for polishing pad, and a method for manufacturing the polishing material.

  A polishing pad is used in a polishing process of an optical material, a semiconductor wafer, a semiconductor device, a hard disk substrate, a liquid crystal glass substrate, or the like. The polishing pad is formed by laminating a polishing layer made of an abrasive material, a base layer made of a nonwoven fabric and the like and an adhesive layer made of a double-sided tape in this order, and is attached to the polishing apparatus by the adhesive layer.

  As the polishing material, a synthetic resin such as hard polyurethane or soft polyurethane, a resin-impregnated nonwoven fabric, or the like is selected according to the type of the object to be polished and the order of the polishing process. In polishing materials for polishing processes that require global flatness, in recent years, hard polyurethanes in which minute hollow spheres are mixed are often used.

  For example, Patent Document 1 describes a polishing pad obtained by impregnating a polymer matrix with polymer microelements having void spaces. In this polishing pad, when the polymer matrix is worn in the polishing process, new polymer microelements appear on the polishing surface, and the hardness of the polishing surface is maintained.

Japanese National Patent Publication No. 08-500622

  In the polishing material containing hollow spheres, the polishing characteristics can be improved by selecting the hollow spheres. Here, the hollow sphere generally has a structure in which a gas is enclosed in an outer shell made of a thermoplastic resin.

  For this reason, when the hollow sphere is heated in the manufacturing process of the polishing material, the thermoplastic resin constituting the outer shell is softened, and the hollow sphere may expand, burst, or permeate and diffuse gas inside. In this case, the effect of the hollow sphere is lost, and desired polishing characteristics cannot be obtained. For example, when heat generated by a polymerization reaction of a polymer containing hollow spheres is accumulated inside the polymer, the hollow spheres are heated thereby, and the thermoplastic resin constituting the outer shell of the hollow spheres may be softened.

  In view of the circumstances as described above, an object of the present invention is to provide a polishing pad excellent in polishing characteristics, a polishing pad sheet, and a method for producing a polishing material.

In order to achieve the above object, a polishing pad according to an embodiment of the present invention includes a polishing layer containing a plurality of hollow spheres and a polymer.
The plurality of hollow spheres have an outer shell made of a thermoplastic resin.
The polymer contains the plurality of hollow spheres and is produced by a polymerization reaction of a prepolymer and a curing agent. The polymer is cured in a time shorter than the time until the internal heat storage by the polymerization reaction reaches the maximum temperature.

  In the above polishing pad, since the polymer is cured in a time shorter than the time when the internal heat storage by the polymerization reaction reaches the maximum temperature, even if the pressure of the gas inside the hollow sphere is increased by heating, the intention of the hollow sphere is Expansion, rupture, or permeation diffusion of the gas is prevented. As a result, it is possible to obtain a polishing pad having desired good polishing characteristics.

The polymer may be cured in a time shorter than the time required to reach the softening temperature of the outer shell of the hollow sphere.
Thereby, since the softening of the thermoplastic resin which comprises the outer shell of a hollow sphere is prevented, it becomes possible to maintain the shape of a hollow sphere.

  The material which comprises the said polymer is not specifically limited, Typically, the said polymer is comprised with the urethane resin produced | generated by the polymerization reaction of an isocyanate group terminal urethane prepolymer and a diamine type hardening | curing agent.

A polishing pad sheet according to one embodiment of the present invention includes a polishing layer containing a plurality of hollow spheres and a polymer.
The plurality of hollow spheres have an outer shell made of a thermoplastic resin.
The polymer contains the plurality of hollow spheres and is produced by a polymerization reaction of a prepolymer and a curing agent. The polymer is cured in a time shorter than the time until the internal heat storage by the polymerization reaction reaches the maximum temperature.
This makes it possible to obtain a polishing pad sheet having desired desired polishing characteristics.

The manufacturing method of the abrasive material which concerns on one form of this invention includes supplying the prepolymer containing the hollow sphere which has the outer shell which consists of thermoplastic resins to a mixing rotor.
A curing agent for producing a polymer by a polymerization reaction with the prepolymer is supplied to the mixing rotor.
The prepolymer and the curing agent are mixed by the mixing rotor so that the curing time of the polymer is shorter than the time when the internal heat storage of the polymer reaches the maximum temperature.
The mixture of the prepolymer and the curing agent is cast into a predetermined shape.

  In the above production method, the polymer is cured in a time shorter than the time when the internal heat storage by the polymerization reaction reaches the maximum temperature, so even if the pressure of the gas inside the hollow sphere is increased by heating, the intention of the hollow sphere Expansion, rupture, or permeation diffusion of the gas is prevented. As a result, it is possible to obtain a polishing pad having desired good polishing characteristics.

  The curing time of the polymer can be controlled by the reaction rate between the prepolymer and the curing agent in the mixing rotor. For example, the reaction rate between the prepolymer and the curing agent can be increased by increasing the shearing force applied to the mixture of the prepolymer and the curing agent in the mixing rotor.

Typically, the mixing rotor is set to a rotation speed at which the curing time of the polymer is shorter than the time until the internal heat storage by the polymerization reaction reaches the maximum temperature.
The curing time of the polymer can be easily controlled by the number of rotations of the mixing rotor.

The prepolymer and the curing agent may be mixed by the mixing rotor so that the curing time of the polymer is shorter than the time required to reach the softening temperature of the outer shell of the hollow sphere.
Thereby, since the softening of the thermoplastic resin which comprises the outer shell of a hollow sphere is prevented, it becomes possible to maintain the shape of a hollow sphere.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the manufacturing method of the polishing pad excellent in the grinding | polishing characteristic, the sheet | seat for polishing pads, and polishing material.

1 is a perspective view of a polishing pad according to an embodiment of the present invention. It is a typical sectional view of the polishing pad. It is typical sectional drawing of the hollow sphere contained in the polishing material which comprises the polishing layer of the polishing pad. It is a schematic diagram which shows the manufacturing equipment of the polishing material which comprises the polishing layer of the polishing pad. It is a schematic diagram which shows the pressure which acts on the hollow sphere contained in the polishing material which comprises the polishing layer of the polishing pad. It is a graph which shows the typical time change of the pressure which acts on the hollow sphere contained in the polishing material which comprises the polishing layer of the polishing pad. It is a graph which shows the time change of the pressure which acts on the said hollow sphere in one Embodiment of this invention. It is a figure which shows the change of the internal temperature of the sample in each experiment example of this invention. It is a cross-sectional SEM image of the sample produced in each said experimental example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Configuration of polishing pad]
FIG. 1 is a perspective view showing a polishing pad 100 according to this embodiment. As shown in the figure, the polishing pad 100 is configured by laminating a polishing layer 101, a base layer 102, and an adhesive layer 103 in this order.

  The polishing layer 101 is a layer that comes into contact with an object to be polished and performs polishing. The polishing layer 101 is made of a polishing material described later. Hereinafter, the main surface of the polishing layer 101 is referred to as a polishing surface 101a. A grid-like groove 101b is formed on the polishing surface 101a. The grooves 101b are for improving the flow of slurry generated in polishing, and are not limited to a lattice shape. The polishing surface 101a may be provided with a number of holes instead of the grooves 101b. Further, the polishing surface 101a may be a flat surface. The thickness of the polishing layer 101 is not particularly limited, and can be, for example, about 0.5 mm to 3.0 mm.

  The base layer 102 is a layer that makes the contact of the polishing layer 101 with the object to be polished uniform. The base layer 102 can be made of a flexible material such as a nonwoven fabric or a synthetic resin. Although the thickness of the base layer 102 is not specifically limited, For example, it can be about 0.1 mm or more and 5 mm or less.

  The adhesive layer 103 is a layer for mounting the polishing pad 100 to the polishing apparatus. The adhesive layer 103 can be made of a double-sided tape affixed to the base layer 102, an adhesive applied to the base layer 102, or the like. The thickness of the adhesive layer 103 is not particularly limited.

  The polishing pad 100 has the above configuration. The size (diameter) of the polishing pad 100 can be determined according to the size of the polishing machine and the like, and can be about several tens of cm to 1 m, for example.

[About polishing materials]
The polishing material constituting the polishing layer 101 will be described. FIG. 2 is a schematic cross-sectional view of the polishing pad 100. As shown in the figure, the polishing layer 101 is made of a polishing material in which a hollow sphere 111 is contained in a polymer 110. In FIG. 2, the description of the groove 101b is omitted.

  The polymer 110 is a main constituent material of the abrasive material. The polymer 110 may be a polymer formed by a polymerization reaction between a prepolymer and a curing agent. Examples of such a polymer include polyurethane. Polyurethane is suitable as a material for the polymer 110 because it has good availability and processability and has suitable polishing characteristics.

  The prepolymer can be a compound having an isocyanate group terminal (hereinafter referred to as an isocyanate compound), for example, diphenylmethane diisocyanate.

  Other isocyanate compounds include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate (2,6-TDI), 2,4-tolylene diisocyanate (2,4-TDI), and naphthalene. -1,4-diisocyanate, diphenylmethane-4,4′-diisocyanate, 3,3′-dimethoxy-4,4′-biphenyl diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, xylylene-1, 4-diisocyanate, 4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate (HDI), isophorone diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate Cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, dicyclohexylmethane-4,4′-diisocyanate (hydrogenated MDI), p-phenylene diisothiocyanate, xylylene-1,4-diisothiocyanate and Ethylidine diisothiocyanate is mentioned. These 1 type (s) or 2 or more types can be made into a prepolymer.

  The curing agent may be an active hydrogen compound having an active hydrogen group that reacts with the terminal isocyanate group of the prepolymer, and examples thereof include a polyamine compound and a polyol compound. The active hydrogen compound reacts with the isocyanate group of the prepolymer to form a hard segment (a urethane bond or a urea bond that imparts rigidity at a high melting point).

  Examples of the polyamine compound include ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4′-diamine, 3,3′-dichloro-4,4′-diaminodiphenylmethane (hereinafter abbreviated as MOCA). And polyamine compounds having the same structure as MOCA. Further, the polyamine compound may have a hydroxyl group, and examples of such a compound include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, and di-2-hydroxyethylpropylene. Examples include diamine, 2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine.

  On the other hand, the polyol compound may be a compound having a plurality of hydroxyl groups such as a diol compound and a triol compound, for example, a low molecular weight polyol compound such as ethylene glycol, butylene glycol and hexanediol, and polytetramethylene ether glycol, Polyether polyol compound such as bis (2-hydroxyethyl) hydroquinone, reaction product of bisphenol A and ethylene oxide, reaction product of bisphenol A and propylene oxide, reaction product of ethylene glycol and adipic acid, butylene glycol and adipic acid And high molecular weight polyol compounds such as polyester polyol compounds, polycarbonate polyol compounds, and polycaprolactone polyol compounds. As the active hydrogen compound, at least one of a polyamine compound and a polyol compound may be used, and two or more of a polyamine compound and a polyol compound may be used in combination.

  In the present embodiment, a diamine-based polyamine compound is used as the curing agent. The diamine-based curing agent has a higher reaction rate with the isocyanate group-terminated urethane prepolymer and therefore has a shorter curing time than the diol-based polyol compound. Thereby, the polymer 110 can be cured in a relatively short time.

  The polymer 110 is not limited to polyurethane, but may be polynorbornene, trans-polyisoprene, styrene-butadiene, or the like. Further, the polymer 110 may include one or more of polyurethane and these resins.

  The hollow sphere 111 is a hollow sphere-like object and is contained in the polymer 110. FIG. 3 is a schematic cross-sectional view of the hollow sphere 111. As shown in the figure, the hollow sphere 111 has a spherical shell-shaped outer shell 111a made of a thermoplastic resin, and an inner space 111b surrounded by the outer shell 111a. The hollow sphere 111 can be formed by wrapping a liquid low-boiling point hydrocarbon in a thermoplastic resin shell and heating.

  The thermoplastic resin is softened by heating, the low boiling point hydrocarbon is changed to gas, and the thermoplastic resin is expanded by the pressure of the gas, whereby the hollow sphere 111 is formed. For example, isobutane or pentane is used as the low boiling point hydrocarbon, and vinylidene chloride or acrylonitrile is used as the thermoplastic resin.

  As the hollow sphere 111, a commercially available product can be used. For example, the Matsumoto Microsphere series (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) or the Expandance series (manufactured by Akzo Nobel) can be used as the hollow sphere 111.

  The size of the hollow sphere 111 is not particularly limited, but can be about several 20 μm to 200 μm in diameter, and two or more types of hollow spheres having different diameters can be used. The content ratio of the hollow sphere 111 in the polishing material is preferably 10 to 60% by volume and more preferably 15 to 45% by volume with respect to the polishing material. When the polishing layer 101 is worn by polishing, the hollow sphere 111 is exposed to the polishing surface 101a and affects the polishing characteristics of the polishing surface 101a. Therefore, the hollow sphere 111 preferably has a uniform distribution.

[About manufacturing method of polishing layer]
A polishing pad sheet made of a polishing material can be used as the polishing layer 101. Hereinafter, the manufacturing method of the sheet | seat for polishing pads is demonstrated. FIG. 4 is a schematic diagram showing an abrasive material manufacturing facility 300. As shown in the figure, the manufacturing facility 300 includes an A-system storage tank 301, a B-system storage tank 302, a mixer 303 (mixing rotor), and a mold 304. The A-system storage tank 301 is provided with a stirring mechanism 305. Each part is provided with temperature control equipment.

  First, the prepolymer and the hollow sphere are charged into the A-system storage tank 301. The A-system storage tank 301 is heated to, for example, about 40 ° C. to 80 ° C. by a heating mechanism, maintains the fluidity of the prepolymer, and defoams. A mixture of the prepolymer and the hollow sphere (hereinafter referred to as prepolymer mixture) is stirred by the stirring mechanism 305 to uniformize the distribution of the hollow sphere in the prepolymer.

  Further, a curing agent is charged into the B-system storage tank 302. The B-system storage tank 302 is heated to, for example, about 40 ° C. to 130 ° C. by a heating mechanism, maintains the fluidity of the curing agent, and defoams.

  Subsequently, the prepolymer mixture is supplied from the A-system storage tank 301 to the mixer 303, and the curing agent is supplied from the B-system storage tank 302 to the mixer 303. The prepolymer mixture and the curing agent can be supplied by a pump provided in the pipe.

  Subsequently, the prepolymer mixture and the curing agent are mixed by the mixer 303. Thereby, a prepolymer and a hardening | curing agent produce a polymerization reaction, and a polymer produces | generates. At this time, reaction heat is generated by the polymerization reaction. A mixture of the produced polymer and the hollow sphere (hereinafter referred to as a polymer mixture) is discharged from the mixer 303 into a mold 304 and cast into a predetermined shape. For example, the mold 304 has a rectangular frame shape of 1 m square, but the size and shape are not limited thereto.

  The mold 304 is heated to, for example, about 40 ° C. to 100 ° C. by the heating mechanism, and accelerates the polymerization reaction of the polymer mixture (primary cure). Note that this heating is not necessarily performed, and the polymer mixture may be allowed to stand until the polymerization reaction proceeds by the reaction heat due to the polymerization reaction.

  Subsequently, the polymer mixture is released from the mold 304 and accommodated in a warmer (not shown). The polymer mixture is heated to about 120 ° C. with an incubator to complete the polymerization reaction (secondary cure).

  Subsequently, the polymer mixture is sliced to a predetermined size. Thereby, the sheet | seat for polishing pads which consists of an abrasive material is manufactured. The polishing pad 100 is manufactured by laminating the base layer 102 and the adhesive layer 103 using the polishing pad sheet as the polishing layer 101. In addition, you may process the groove | channel 101b etc. to the grinding | polishing layer 101 as needed.

[Maintenance of hollow sphere shape]
As described above, when the prepolymer mixture containing the hollow sphere and the prepolymer and the curing agent are mixed, the prepolymer and the curing agent cause a polymerization reaction. The reaction heat at this time may cause deformation of the hollow sphere.

FIG. 5 is a schematic diagram showing the pressure acting on the hollow sphere 111. In the figure, it is assumed that a polymer exists around the hollow sphere 111. As shown in the figure, the hollow sphere 111, the internal pressure _{P in} the external pressure _{P out} is applied. FIG. 6 is a graph showing typical time changes of the internal pressure P _in and the external pressure P _out , and the origin is the start time of the polymerization reaction and the pressure at that time.

The internal pressure Pin is a pressure generated by the expansion of the gas contained _in the internal space 111b. If hollow spheres 111 by heat due to the polymerization reaction at the periphery of the hollow sphere 111 is heated, the gas expands contained in the inner space 111b, the internal pressure P _in occurs. The internal pressure P _in can be approximated by the gas equation of state (P _in V = nRT, where V is the volume of the internal space, n is the number of moles of gas, R is the gas constant, and T is the absolute temperature of the gas. . pressure P _in is gradually increased by an internal heat accumulation due to the polymerization reaction of the polymer as shown in FIG. 6, gradually decreases by the decrease of the internal heat storage the polymerization reaction proceeds.

The external pressure _Pout is a pressure received from the surrounding polymer when the hollow sphere 111 is about to expand. The viscous resistance F received by the hollow sphere 111 is proportional to the polymer viscosity according to the Stokes equation (F = 6πηrv, η is the polymer viscosity, r is the radius of the hollow sphere, and v is the volume of the hollow sphere). Therefore, the external pressure P _out increases in proportion to the polymer viscosity. As shown in FIG. 6, the external pressure P _out gradually increases as the polymer becomes highly viscous (cured) by the polymerization reaction, and becomes substantially constant after the curing time (T1 in the figure).

And the internal pressure _{P in} is greater than the external pressure _{P out,} the internal space 111b is trying to expansion, and the internal pressure _{P in} is less than the external pressure _{P out,} the internal space 111b is trying to shrink. However, since the inner space 111b is surrounded by the outer shell 111a, the shape of the hollow sphere 111 is maintained if the outer shell 111a is solid.

Here, since the outer shell 111a is made of a thermoplastic resin, the outer shell 111a softens when its temperature exceeds the softening temperature of the thermoplastic resin. Therefore, temperature pressure _{P in} a higher than the softening temperature condition of the outer shell 111a is external pressure _{P out} is greater than the hollow sphere 111 is inflated. In FIG. 6, the internal pressure at the softening temperature of the thermoplastic resin constituting the outer shell 111a is shown as a pressure P1. That is, _{in the} region where the temperature of the thermoplastic resin is higher than the softening temperature and the internal pressure _{Pin is} larger than the external pressure Pout (shaded region in the figure), the expansion of the internal space 111b cannot be suppressed by the outer shell 111a, and the hollow sphere 111 expands.

In this case, the hollow sphere 111 may rupture or the outer shell 111a may become thin, so that the gas in the inner space 111b may permeate the outer shell 111a. The temperature of the outer shell 111a is pressure _{P in} at above the softening temperature conditions external pressure _{P out} is smaller than the hollow sphere 111 shrinks.

  When the hollow sphere 111 is ruptured or the gas in the internal space 111b permeates through the outer shell 111a, the polishing characteristics of the polishing layer 101 are greatly affected.

[Manufacturing method of this embodiment]
In the present embodiment, the shape of the hollow sphere 111 is maintained, and the influence on the polishing characteristics due to the deformation of the hollow sphere 111 is prevented. Specifically, the curing time (T1) of the polymer 110 is made shorter than the time (T2) until the internal heat storage of the polymer 110 due to the polymerization reaction reaches the maximum temperature. More preferably, the curing time (T1) of the polymer 110 is shorter than the time (T3) until the softening temperature of the outer shell 111a of the hollow sphere 111 is reached.

Figure 7 is a graph showing the time variation of the internal pressure _{P in} the external pressure _{P out} showing the production conditions of the polymer 110 in the present embodiment.

Even if the pressure increase of the gas inside the hollow sphere 111 is caused by heating by curing the polymer 110 in a time (T1) shorter than the time (T1) in which the internal heat storage due to the polymerization reaction of the polymer 110 reaches the maximum temperature, Since the relationship of the internal pressure P _in ≦ the external pressure P _out can be maintained, unintended expansion and rupture of the hollow sphere 111 or permeation and diffusion of the gas is prevented.

  In addition, by setting the curing time (T1) of the polymer 110 to be shorter than the time (T3) until the softening temperature of the outer shell 111a of the hollow sphere 111 is reached, the thermoplastic resin constituting the outer shell 111a of the hollow sphere 111 Can be prevented, and the shape of the hollow sphere 111 can be maintained.

  In the present embodiment, the curing time (T1) of the polymer 110 is adjusted by the mixing step of the prepolymer mixture and the curing agent in the mixer 303. That is, in the mixer 303, the prepolymer mixture and the curing agent are mixed so that the curing time (T1) of the polymer 110 is shorter than the time (T2) when the internal heat storage of the polymer 110 reaches the maximum temperature.

  The mixer 303 is provided with a rotor 303a (FIG. 4) for stirring the polymer mixture. The prepolymer is cured by a polymerization reaction with a curing agent, and the internal heat storage temperature resulting from the polymerization reaction is increased. The higher the stirring action in the mixer 303, that is, the greater the shear stress acting on the polymer mixture, the more the polymerization reaction with the curing agent is promoted. And the hardening time of the polymer 110 can be shortened, so that a polymerization reaction rate is high. Therefore, the condition of T1 <T2 can be satisfied by generating a shearing force capable of curing the polymer mixture by the time (T2) when the internal heat storage by the polymerization reaction reaches the maximum temperature.

Here, of course, the curing time (T1) of the polymer mixture is not limited to the time until the curing rate of the polymer mixture reaches 100%. The curing time (T1) may be a time required to reach a hardness that allows the external pressure (P _out ) capable of preventing the expansion of the hollow sphere 111 due to internal heat storage to act on the hollow sphere 111. In this embodiment, the curing time of the polymer mixture The time until the viscosity reaches 50000 mPa · s is shown.

  Also, the polymer curing time (T1) is typically longer than the time the polymer mixture stays in the mixer 303. Accordingly, since the polymer mixture discharged from the mixer 303 to the mold 304 has a certain fluidity, the moldability by the mold 304 is ensured. Further, when the heating treatment of the polymer mixture in the mold 304 is performed, the shearing force in the mixer 303 may be set in consideration of the curing reaction of the polymer mixture by the heating treatment.

  The magnitude of the shearing force in the mixer 303 is typically adjusted by the number of rotations of the rotor 303a. That is, the higher the number of rotations of the rotor 303a, the greater the shearing force that can be obtained, and the polymerization reaction of the polymer mixture is promoted. The number of rotations of the rotor 303a is not particularly limited, and is set to 1000 to 4000 rpm, for example.

  The inventors changed the internal temperature of the polymer mixture when the rotation speed of the rotor 303a was set to 1000 rpm (Experimental Example 1), 2000 rpm (Experimental Example 2), 3000 rpm (Experimental Example 3), and 4000 rpm (Experimental Example 4). And the cross-sectional structure was examined.

  The internal temperature of the cast polymer mixture is measured by measuring the internal temperature of the polymer mixture by using a temperature sensor installed at the bottom of the mold and projecting the temperature measuring point of the temperature sensor to the inside. Was measured directly. The measurement of the internal temperature was recorded at intervals of 15 seconds from the start of casting until the reaction proceeded to some extent, and was recorded at intervals of 5 minutes after the temperature change decreased.

  The prepolymer, hollow sphere, and curing agent used in Experimental Examples 1 to 4 are the same, and the prepolymer includes a prepolymer (NCO equivalent 460) mainly composed of 2,4-tolylene diisocyanate (TDI). As the curing agent, 4,4′-methylene-bis [2-chloroniline] (MOCA) was used. As the hollow sphere, “EXPANCEL551DE40d42” (manufactured by AkzoNobel, softening temperature 130 ° C.) having an average particle diameter of 30 to 50 μm was used. The sample preparation conditions were the same except for the number of revolutions of the mixing rotor, the temperature of the A-system storage tank was 60 ° C., the temperature of the B-system storage tank was 120 ° C., and the mold temperature was 80 ° C.

  FIG. 8 is a diagram showing changes in the internal temperature of the samples in Experimental Examples 1 to 4. As the number of rotations of the mixing rotor is increased, the number of collisions of molecules increases, so that the reaction speed increases. For this reason, as shown in FIG. 8, the internal temperature also increases as the rotational speed is increased. In addition, since the time until the internal temperature reaches the peak (T2) is almost the same in each experimental example, it has been confirmed that the time until the internal temperature reaches the peak value does not significantly affect the time. It was done. On the other hand, since the reaction rate increases as the number of rotations of the mixing rotor is increased, the curing rate of the polymer also increases. Table 1 summarizes the polymer curing time (T1), the time when the internal temperature reaches the peak (T2), and the time when the outer shell of the hollow sphere reaches the softening temperature (T3) in Experimental Examples 1 to 4.

  As shown in Table 1, T1 <T2 in any of Experimental Examples 1 to 4, T1> T3 in Experimental Examples 1 and 2, and T1 <T3 in Experimental Examples 3 and 4. As described above, since the curing time (T1) of the polymer can be controlled by the number of rotations of the mixing rotor, the relationship of T1 <T2 and further T1 <T3 can be easily realized.

  FIG. 9 shows cross-sectional SEM images (50 times and 200 times) of the samples produced in Experimental Examples 1 to 4. In addition, Table 2 shows the density, D hardness, and average size (Pore size) and number (Pore count) of hollow spheres in the cross section measured for each sample. Note that the number of hollow spheres was 10 μm or more in diameter.

  As shown in FIG. 9, it was confirmed that the bursting of the hollow spheres was also suppressed in each experimental example. Further, as shown in FIG. 9 and Table 2, it was confirmed that the density and hardness tend to increase as the number of rotations of the mixing rotor is increased. Also in this case, it is considered that the shear force applied to the polymer increases as the number of rotations increases, the number of molecular collisions increases, and the reaction rate and reaction efficiency are improved.

On the other hand, the average size of the hollow spheres was almost constant regardless of the rotational speed of the mixing rotor, whereas the number tended to decrease as the rotational speed of the mixing rotor was increased. This is considered to be due to the presence or absence of expansion of hollow spheres of 10 μm or less, which are cut off (not subject) in the cross-sectional SEM image. Pressure P _in is to be approximated by the equation of state of gas (P _{in V =} nRT) are as described above, when the number of moles of gas in the interior of the hollow spheres are the same, and inversely proportional to the volume of hollow spheres the internal pressure _{P in} the greater Te. Accordingly, the hollow sphere having a small radius is more easily expanded than the one having a large radius. That is, in Experimental Examples 1 and 2 where the number of rotations of the mixing rotor is low, the curing time becomes long, so it is considered that the hollow spheres that were 10 μm or less before the reaction have expanded, while the rotation of the mixing rotor In Experimental Examples 3 and 4 where the number was increased, the curing time was short, and the hollow spheres that were 10 μm or less before the reaction did not expand so much, so the number of hollow spheres counted in the cross-sectional SEM image decreased as the number of rotations increased. It is possible to do. In this way, by adjusting the number of rotations of the mixing rotor, the density and hardness of the produced polishing layer can be controlled, so that it is possible to easily produce a polishing pad having desired polishing characteristics. Become.

  As mentioned above, although embodiment of this invention was described, this invention is not limited only to the above-mentioned embodiment, Of course, a various change can be added.

  For example, in the above embodiment, the example in which the curing time of the polymer is controlled by the number of rotations of the mixing rotor has been described. However, the present invention is not limited to this. It is also possible to control the curing time of the polymer depending on the factors.

  In the above embodiment, the prepolymer mixture in which the hollow sphere is mixed with the prepolymer is supplied from the A-system storage tank to the mixing rotor. However, the hollow sphere may be supplied to the mixing rotor separately from the prepolymer. Good.

DESCRIPTION OF SYMBOLS 100 ... Polishing pad 101 ... Polishing layer 102 ... Base layer 103 ... Adhesive layer 110 ... Polymer 111 ... Hollow sphere

Claims (7)

A plurality of hollow spheres having an outer shell made of a thermoplastic resin;
A polishing layer containing the plurality of hollow spheres and produced by a polymerization reaction of a prepolymer and a curing agent and cured in a time shorter than a time required for internal heat storage by the polymerization reaction to reach a maximum temperature. A polishing pad comprising:
The polishing pad, wherein the polymer is a polymer cured in a time shorter than a time required to reach a softening temperature of the thermoplastic resin contained in the outer shell of the hollow sphere . The polishing pad according to claim 1,
The outer shell of the hollow sphere is a polishing pad made of a thermoplastic resin containing vinylidene chloride and acrylonitrile, and the softening temperature is 130 ° C. The polishing pad according to claim 1 or 2,
The polymer, a polishing pad composed of a polymer of an isocyanate group-terminated urethane prepolymer and a diamine curing agent. A plurality of hollow spheres having an outer shell made of a thermoplastic resin;
A polishing layer containing the plurality of hollow spheres and produced by a polymerization reaction of a prepolymer and a curing agent and cured in a time shorter than a time required for internal heat storage by the polymerization reaction to reach a maximum temperature. A polishing pad sheet comprising:
The polishing pad sheet, wherein the polymer is a polymer cured in a time shorter than a time required to reach a softening temperature of the thermoplastic resin contained in the outer shell of the hollow sphere . Supplying a prepolymer containing a hollow sphere having an outer shell made of a thermoplastic resin to a mixing rotor;
A curing agent for producing a polymer by polymerization reaction with the prepolymer is supplied to the mixing rotor,
The curing time of the polymer is shorter than the time for the internal heat storage of the polymer to reach the maximum temperature, and the time for the curing time of the polymer to reach the softening temperature of the thermoplastic resin contained in the outer shell of the hollow sphere. The prepolymer and the curing agent are mixed by the mixing rotor,
A method for producing an abrasive material, wherein a mixture of the prepolymer and the curing agent is cast into a predetermined shape. A method for producing an abrasive material according to claim 5,
In the mixing rotor, the curing time of the polymer is set to a rotational speed that is shorter than the time until the internal heat storage by the polymerization reaction reaches the maximum temperature. A method for producing an abrasive material according to claim 5 or 6,
The outer shell of the hollow sphere is made of a thermoplastic resin containing a vinylidene chloride and acrylonitrile, as the curing time of the polymer becomes shorter than the time until reaching 130 ° C., and the prepolymer by the mixing rotor A method for producing an abrasive material comprising mixing the curing agent.