Polishing composition, method for producing polishing composition, and polishing method

Abstract

[Problem] To provide a polishing composition that has a superior working force and that has good washability after polishing. [Solution] A polishing composition including: abrasive grains; water; and a hydrophobic dispersion medium. The hydrophobic dispersion medium includes at least one type selected from the group consisting of normal paraffin hydrocarbons, isoparaffin hydrocarbons, naphthene hydrocarbons, and terpene hydrocarbons. The polishing composition has a flash point of 30-100℃ or a vapor pressure at 20℃ of 0.004-2 kPa or less.

Description

[Technical Field]

[0001] The present invention relates to a polishing composition, a method for producing a polishing composition, and a polishing method. [Background technology]

[0002] Painted surfaces, such as automobile bodies, are polished to remove scratches that occur during use and to create a uniform paint finish when repainting to repair scratches. In this case, it is required that the polished painted surface be free of scratches, that the base color be clearly visible, and that the surface not appear whitish due to fine scratches that occur during polishing. A known method for polishing painted surfaces involves using a buff (abrasive wheel) and a polisher (sanding machine) attached to rotate the buff, with a polishing composition interposed between the painted surface and the buff, and rotating the buff with the polisher. Examples of such polishing compositions include the polishing composition described in Patent Document 1.

[0003] Typical buffs used to polish painted surfaces such as car bodies include wool buffs (sheep wool buffs) and sponge buffs (urethane foam buffs). Generally, the process of removing scratches from painted surfaces is divided into rough polishing and finish polishing. Rough polishing aims to remove scratches from the painted surface, while finish polishing aims to remove tiny scratches and white spots on the painted surface that occur during rough polishing. Wool buffs are used for rough polishing, while sponge buffs are used for finish polishing. While it may be possible to remove scratches with finish polishing alone, combining rough polishing and finish polishing allows the polishing to be completed in a shorter time.

[0004] Polishing of a painted surface is carried out by dropping an appropriate amount of abrasive (polishing composition) onto the painted surface or onto the surface of a buff, and then spreading the abrasive on the painted surface with a buff. The buff is rotated by a polisher and moved against the painted surface, and ideally, polishing of the painted surface is complete after the buff has passed, with no abrasive remaining on the painted surface. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-251099 Summary of the Invention [Problem to be solved by the invention]

[0006] The polishing composition described in Patent Document 1 is characterized by maintaining the polished surface in a wet state after polishing. However, such a polishing composition is difficult to dry, and depending on the amount of polishing composition supplied, the liquid film formed at the interface between the buff and the coated surface becomes thicker than necessary, suppressing contact of the abrasive grains with the coated surface and resulting in a decrease in processing power. Processing power refers to the force that physically removes the workpiece, such as the force with which the abrasive grains create fine scratches on the surface of the workpiece. Furthermore, a polishing composition that remains wet tends to remain on the coated surface, making it difficult to wipe off after polishing. In addition, in finish polishing, the polishing composition adheres firmly to the coated surface, resulting in a problem of insufficient gloss. This phenomenon is particularly likely to occur with soft coatings.

[0007] Therefore, an object of the present invention is to provide a polishing composition that has excellent processing power and good cleanability after polishing. [Means for solving the problem]

[0008] In order to solve the above problems, the present inventors have conducted extensive research and have found that the above problems can be solved by a polishing composition comprising abrasive grains, water, and a hydrophobic dispersion medium, wherein the hydrophobic dispersion medium comprises at least one selected from the group consisting of normal paraffinic hydrocarbons, isoparaffinic hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons, and has a flash point of 30°C to 100°C, or a polishing composition comprising abrasive grains, water, and a hydrophobic dispersion medium, wherein the hydrophobic dispersion medium comprises at least one selected from the group consisting of normal paraffinic hydrocarbons, isoparaffinic hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons, and has a vapor pressure at 20°C of 0.004 kPa to 2 kPa, thereby completing the present invention. [Effects of the Invention]

[0009] According to the present invention, there is provided a polishing composition which has excellent processing power and good cleanability after polishing. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes embodiments of the present invention, but the present invention is not limited to these. Unless otherwise specified, operations and measurements of physical properties are performed at room temperature (20°C to 25°C) and a relative humidity of 30% RH to 50% RH.

[0011] <Polishing composition> A first embodiment of the present invention is a polishing composition comprising abrasive grains, water, and a hydrophobic dispersion medium, wherein the hydrophobic dispersion medium comprises at least one selected from the group consisting of normal paraffinic hydrocarbons, isoparaffinic hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons, and has a flash point of 30° C. to 100° C. A second embodiment of the present invention is a polishing composition comprising abrasive grains, water, and a hydrophobic dispersion medium, wherein the hydrophobic dispersion medium comprises at least one selected from the group consisting of normal paraffinic hydrocarbons, isoparaffinic hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons, and has a vapor pressure at 20° C. of 0.004 kPa to 2 kPa.

[0012] The polishing composition of the present invention having such a constitution has excellent processing power when polishing an object to be polished as rough polishing or finish polishing, and also has good cleanability after polishing. Here, "excellent processing power" means, for example, that in the evaluation of processing power in the removal (elimination) of scratches after polishing, the time required to remove (eliminate) the scratches is short, and in the evaluation of processing power in the removal amount (removal rate), the removal amount is large (high removal rate). Furthermore, "good cleanability after polishing" means that little of the polishing composition remains on the coating surface after polishing, that is, the time required to remove the residue (cleaning time) is short. Furthermore, the polishing composition of the present invention can suppress adhesion to the coating surface after polishing in finish polishing, thereby preventing the adhesion from causing insufficient gloss to be obtained.

[0013] The polishing composition of the present invention contains a hydrophobic dispersion medium having a flash point of 30°C or higher and 100°C or lower, or a vapor pressure at 20°C of 0.004 kPa or higher and 2 kPa or lower. The present inventors focused on the flash point and vapor pressure of the hydrophobic dispersion medium constituting the polishing composition, and discovered a novel polishing composition that has excellent processing power during polishing and cleanability after polishing when the flash point or vapor pressure of the hydrophobic dispersion medium is within a specific range. The reason why the polishing composition of the present invention exhibits the above effects is not necessarily clear.

[0014] A third embodiment of the present invention is a polishing composition comprising abrasive grains, water, and a hydrophobic dispersion medium, wherein the hydrophobic dispersion medium comprises at least one selected from the group consisting of normal paraffin hydrocarbons, isoparaffin hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons, and has a vapor pressure at 20°C of 0.004 kPa or more and 2 kPa or less and a flash point of 30°C or more and 100°C or less.

[0015] That is, the present invention is a polishing composition comprising abrasive grains, water, and a hydrophobic dispersing medium, wherein the hydrophobic dispersing medium comprises at least one selected from the group consisting of normal paraffin hydrocarbons, isoparaffin hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons, and the polishing composition has a vapor pressure at 20°C of 0.004 kPa or more and 2 kPa or less and / or a flash point of 30°C or more and 100°C or less.

[0016] Here, in this specification, "A and / or B" is synonymous with "at least one of A and B" and means to include all of the forms of A only, B only, and both A and B. That is, "the hydrophobic dispersion medium has a vapor pressure of 0.004 kPa to 2 kPa at 20°C and / or a flash point of 30°C to 100°C" means any one of the following: a hydrophobic dispersion medium having a vapor pressure of 0.004 kPa to 2 kPa at 20°C; a hydrophobic dispersion medium having a flash point of 30°C to 100°C; and a hydrophobic dispersion medium having a vapor pressure of 0.004 kPa to 2 kPa at 20°C and a flash point of 30°C to 100°C. In addition, the preferred embodiments of the present invention described below are suitably applied to any of the first to third embodiments of the present invention.

[0017] Each component contained in the polishing composition of the present invention will be described below.

[0018] [Abrasive grain] The polishing composition of the present embodiment contains abrasive grains. The abrasive grains have the function of mechanically polishing an object to be polished.

[0019] Specific examples of abrasive grains used in this embodiment include metal oxides such as aluminum oxide (alumina), silicon oxide (silica), cerium oxide (ceria), zirconium oxide, titanium oxide (titania), tin oxide, and manganese oxide; metal carbides such as silicon carbide and titanium carbide; metal nitrides such as silicon nitride and titanium nitride; metal borides such as titanium boride and tungsten boride; silicate compounds such as zircon (ZrSiO4); and diamond. The abrasive grains may be used alone or in combination. Furthermore, commercially available or synthetic abrasive grains may be used.

[0020] Among these abrasive grains, at least one selected from the group consisting of metal oxides and metal carbides is preferred, silicon carbide, silicon dioxide, or a metal oxide is more preferred, and at least one of aluminum oxide (alumina), cerium oxide, and zirconium oxide is even more preferred, with aluminum oxide being particularly preferred. Also, a mixture of alumina and zirconium can be preferably used.

[0021] Furthermore, among aluminum oxides, the preferred crystalline structure for abrasive grains is one containing an α-phase or a transition-state crystalline phase, such as a θ-phase, δ-phase, or γ-phase, which is in the process of becoming the α-phase. Preferably, the α-phase or θ-phase is contained, and more preferably, the α-phase is contained. Regarding the α-phase, an optimal range is believed to exist depending on the degree of α-phase formation. Generally, the α-phase crystal structure is considered to be the hardest, but if sintered sufficiently at high temperatures to form the α-phase, the particle shape is thought to become rounded, resulting in a decrease in polishing performance. The α-phase ratio can be used as a reference value to represent the degree of α-phase contained in aluminum oxide. The preferred lower limit of the α-phase ratio is 50% or more. The lower limit of the α-phase ratio is more preferably 60% or more, even more preferably 70% or more, particularly preferably 80% or more, and even more preferably 90% or more. The preferred upper limit of the α-phase ratio is 100% or less. The upper limit of the α-phase ratio is more preferably 98% or less. That is, the alpha phase ratio of aluminum oxide is preferably 50% or more and 100% or less, and more preferably 60% or more and 98% or less. By setting the alpha phase ratio within the above preferred range, improvement in polishing power, i.e., faster scratch removal speed and improved polishing rate, can be expected. The alpha phase ratio of aluminum oxide particles can be calculated from the integrated intensity ratio of the (113) plane diffraction line by X-ray diffraction measurement using an X-ray diffractometer (Ultima-IV, manufactured by Rigaku Corporation).

[0022] The lower limit of the volume average particle diameter (average secondary particle diameter) of the abrasive grains is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 0.2 μm or more. By having the volume average particle diameter (average secondary particle diameter) of the abrasive grains be 0.05 μm or more, the processing power can be improved, and the object to be polished can be polished well in both rough polishing and finish polishing. Furthermore, the upper limit of the volume average particle diameter (average secondary particle diameter) of the abrasive grains is preferably 15 μm or less, more preferably 10 μm or less, even more preferably 5 μm or less, particularly preferably 4 μm or less, and most preferably 3 μm or less. As the volume average particle diameter (average secondary particle diameter) of the abrasive grains decreases, it becomes easier to obtain a surface with fewer defects and less roughness. Therefore, by having the volume average particle diameter (average secondary particle diameter) of the abrasive grains be 0.05 μm or more and 15 μm or less, the processing power can be improved while obtaining a surface with fewer defects and less roughness. Abrasive grains that have a large particle size before polishing but become smaller at the interface between the buff and the object to be polished during polishing (abrasive grains in which secondary particles break down to primary particles during polishing) may also be used. Based on the above, the volume average particle size (average secondary particle size) of the abrasive grains is preferably 0.05 μm to 15 μm, more preferably 0.1 μm to 10 μm, even more preferably 0.2 μm to 5 μm, particularly preferably 0.2 μm to 4 μm, and most preferably 0.2 μm to 3 μm. In one embodiment, the volume average particle size (average secondary particle size) of the abrasive grains is 0.05 μm to 10 μm, 0.2 μm to 4 μm, or 0.2 μm to 3 μm.

[0023] In this specification, the volume-average particle size of abrasive grains is defined as the cumulative 50% particle size (D50) based on the volume-based particle size distribution. The D50 of abrasive grains can be measured using a commercially available particle size measuring device. Such particle size measuring devices may be based on any of the following techniques: dynamic light scattering, laser diffraction, laser scattering, or pore electrical resistance. Examples of methods and devices for measuring D50 include those described in the Examples.

[0024] The lower limit of the content of abrasive grains in the polishing composition is preferably 0.1 mass % or more, more preferably 1 mass % or more, even more preferably 5 mass % or more, particularly preferably 7 mass % or more, and most preferably 10 mass % or more, based on the total mass of the polishing composition. By having the content of abrasive grains be 0.1 mass % or more, the processing force can be appropriately controlled, and the object to be polished can be polished well in both rough polishing and finish polishing.

[0025] The upper limit of the content of abrasive grains in the polishing composition is preferably 50% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less, particularly preferably 20% by mass or less, and most preferably 15% by mass or less, based on the total mass of the polishing composition. By making the content of abrasive grains 50% by mass or less, the production cost of the polishing composition can be reduced, and a surface with low defects and low roughness can be obtained.

[0026] In a preferred embodiment, the abrasive grains are contained in an amount of 5% by mass or more and 30% by mass or less based on the total mass of the polishing composition.

[0027] [water] The polishing composition according to this embodiment contains water. From the viewpoint of suppressing the inhibition of the action of other components, the water preferably contains as few impurities as possible. Specifically, pure water or ultrapure water obtained by removing impurity ions with an ion exchange resin and then passing the water through a filter to remove foreign matter, or distilled water is preferred.

[0028] The lower limit of the water content in the polishing composition is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, particularly preferably 15% by mass or more, and most preferably 20% by mass or more, based on the total mass of the polishing composition. The upper limit of the water content in the polishing composition is preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 80% by mass or less, particularly preferably 75% by mass or less, and most preferably 70% by mass or less, based on the total mass of the polishing composition. That is, the water content in the polishing composition is preferably 1% by mass or more and 90% by mass or less, more preferably 5% by mass or more and 85% by mass or less, even more preferably 10% by mass or more and 80% by mass or less, particularly preferably 15% by mass or more and 75% by mass or less, and most preferably 20% by mass or more and 70% by mass or less. The water content within the above range improves the processing power, and the object to be polished can be polished well in both rough polishing and finish polishing.

[0029] [Hydrophobic dispersion medium] The polishing composition according to this embodiment contains a hydrophobic dispersion medium. The hydrophobic dispersion medium contains at least one selected from the group consisting of normal paraffinic hydrocarbons, isoparaffinic hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons, and has a vapor pressure at 20°C of 0.004 kPa to 2 kPa and / or a flash point of 30°C to 100°C. Hereinafter, the normal paraffinic hydrocarbons, isoparaffinic hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons that may be contained in the hydrophobic dispersion medium may be referred to as "organic solvents." In this embodiment, the hydrophobic dispersion medium and organic solvent are preferably those that are not easily soluble in water. The hydrophobic dispersion medium and organic solvent may be commercially available or synthetic. In this specification, the vapor pressure at 20°C is also referred to as "vapor pressure (20°C)."

[0030] Normal paraffin hydrocarbons, isoparaffin hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons are preferably derived from mineral oil, and may be obtained by extracting and refining components derived from mineral oil, or may be synthesized using components derived from mineral oil as raw materials (synthetic hydrocarbons derived from mineral oil). Normal paraffin hydrocarbons, isoparaffin hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons are more preferably synthetic hydrocarbons derived from mineral oil. These hydrophobic organic solvents are generally known to be less toxic than other halogen-based or benzene-based organic solvents, and more volatile than other polyethylene glycols, etc.

[0031] Examples of normal paraffin hydrocarbons include linear hydrocarbons having from 5 to 30 carbon atoms, liquid paraffin, kerosene, and diesel.

[0032] Examples of isoparaffin hydrocarbons include branched hydrocarbons having 5 to 40 carbon atoms, liquid isoparaffin, and the like.

[0033] Examples of naphthenic hydrocarbons include cyclic hydrocarbons having from 5 to about 40 carbon atoms, such as monocyclic cycloparaffins such as cyclohexane, cyclopentane, and cyclononane; polycyclic cycloparaffins such as decalin; and alkylcycloparaffins such as methylcyclopentane, methylcyclohexane, 1-methyl-4-isopropylcyclohexane, butylcyclohexane, and methyldecalin.

[0034] Examples of terpene hydrocarbons include chain terpene hydrocarbons such as myrcene, farnesene, and citral; and cyclic terpene hydrocarbons such as menthol, cineole, pinene, limonene, α-terpinene, γ-terpinene, camphene, phellandrene, terpinene, terpinolene, p-cymene, and cedrene.

[0035] The hydrophobic dispersion medium may further contain organic solvents other than the above-mentioned hydrocarbons, as long as the flash point satisfies the above range and does not impair the effects of the present invention. Hereinafter, organic solvents other than normal paraffin hydrocarbons, isoparaffin hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons will be referred to as "other organic solvents." Examples of such other organic solvents include methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, diethyl ether, ethyl acetate, butyl acetate, triethyl citrate, acetyl tributyl citrate, and acetyl triethyl citrate.

[0036] Hydrophobic dispersion media (organic solvents) generally have a flash point. The flash point is the lowest temperature at which a liquid generates sufficient vapor to instantly ignite when heated at a constant temperature and exposed to a flame. The flash point can also be defined as the lowest temperature at which the hydrophobic dispersion media evaporates and forms a flammable mixture with air. There are various methods for measuring flash point, depending on the purpose of the measurement and the properties of the sample. Flash point can be measured using either the closed-circuit method or the open-circuit method. Examples of closed-circuit methods include the Tag closed-circuit method (JIS K 2265-1:2007), the Seta closed-circuit method (JIS K 2265-2:2007), and the Pensky-Martens closed-circuit method (JIS K 2265-3:2007). Examples of open-circuit methods include the Cleveland open-circuit method (JIS K 2265-4:2007).

[0037] In one embodiment of the present invention, the hydrophobic dispersion medium has a flash point of 30°C or higher and 100°C or lower. If the flash point of the hydrophobic dispersion medium is 30°C or higher, the hydrophobic dispersion medium is prevented from volatilizing too much during polishing, preventing the liquid film formed at the polishing interface from being maintained and polishing from proceeding, thereby achieving the desired effect of the present invention. If the flash point of the hydrophobic dispersion medium is 100°C or lower, the hydrophobic dispersion medium is prevented from volatilizing during polishing, preventing the liquid film formed at the polishing interface from becoming too thick and preventing the abrasive grains from processing the coating, thereby achieving the desired effect of the present invention.

[0038] The hydrophobic dispersion medium may be composed of only one organic solvent, but may also be a mixture of two or more organic solvents as long as it has a flash point of 30°C or higher and 100°C or lower. That is, in one embodiment, the hydrophobic dispersion medium contains at least two organic solvents selected from the group consisting of normal paraffinic hydrocarbons, isoparaffinic hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons. Note that "containing at least two organic solvents" also includes, for example, the case where the hydrophobic dispersion medium contains two or more isoparaffinic hydrocarbons. In the present invention, even when the hydrophobic dispersion medium contains two or more organic solvents, the flash point of the hydrophobic dispersion medium (the FPI flash point described below) is 30°C or higher and 100°C or lower. In this specification, when the hydrophobic dispersion medium is composed of a single organic solvent, the flash point of the hydrophobic dispersion medium means a flash point measured by any of the above methods. Furthermore, in this specification, when the hydrophobic dispersion medium contains two or more organic solvents, the flash point of the hydrophobic dispersion medium means the flash point calculated from the Flash-Point Blending Index (abbreviated as FPI) (hereinafter also referred to as "FPI flash point").

[0039] The flash point mixing index for calculating the FPI flash point is determined from the flash point mixing index table described in Hydrocarbon Processing & Petroleum Refiner, June 1963, Vol. 42, No. 6. For example, a flash point of 190 o Oil A has a flash point of 330°F (87.8°C). o The flash point of a mixture of oil A and oil B at a temperature of 165.6°C (30:70 by volume) is calculated as follows: Based on the flash point blending index table in the above document, the FPI of oil A is 30 and the FPI of oil B is 1.0. Calculating the FPI of the mixture using the FPI of each oil is "mixture FPI = (30 / 100) x (30) + (70 / 100) x (1.0) = 9.7". Applying this FPI of 9.7 to the flash point blending index, the flash point corresponding to an FPI of 9.7 is approximately 230 oF (110°C). When two or more organic solvents are mixed and used, it is sufficient to be able to actually measure the flash point of the mixture, but this may not be possible depending on the circumstances. In such cases, the flash point of the mixture can be calculated using the flash point mixing index. In the present invention, when the hydrophobic dispersion medium contains two or more organic solvents, the flash point is calculated using the flash point mixing index.

[0040] In one embodiment of the present invention, the hydrophobic dispersion medium preferably has a lower flash point limit of 30°C or higher. The hydrophobic dispersion medium preferably has a lower flash point limit of 40°C or higher, more preferably 50°C or higher, even more preferably 55°C or higher, even more preferably 64°C or higher, particularly preferably 65°C or higher, and most preferably 66°C or higher. Having a flash point of 40°C or higher allows the desired effects of the present invention to be achieved more efficiently. In one embodiment of the present invention, the hydrophobic dispersion medium preferably has an upper flash point limit of 100°C or lower. The hydrophobic dispersion medium preferably has an upper flash point limit of 95°C or lower, more preferably 90°C or lower, even more preferably 85°C or lower, even more preferably 80°C or lower, particularly preferably less than 75°C, and most preferably 70°C or lower. Having a flash point of 95°C or lower allows the desired effects of the present invention to be achieved more efficiently.

[0041] That is, in one embodiment of the present invention, the hydrophobic dispersion medium has a flash point of 30°C or higher and 100°C or lower. In one embodiment of the present invention, when the vapor pressure (20°C) of the hydrophobic dispersion medium is 0.004 kPa or higher and 2 kPa or lower, the flash point of the hydrophobic dispersion medium is preferably 30°C or higher and 100°C or lower. In one embodiment of the present invention, the flash point of the hydrophobic dispersion medium is preferably 40°C or higher and 95°C or lower, more preferably 50°C or higher and 90°C or lower, even more preferably 55°C or higher and 85°C or lower, still more preferably 64°C or higher and 80°C or lower, particularly preferably 65°C or higher and lower than 75°C, and most preferably 66°C or higher and 70°C or lower. In one embodiment, the flash point of the hydrophobic dispersion medium is 50°C or higher and 80°C or lower. In one embodiment, the flash point of the hydrophobic dispersion medium is 64°C or higher and 74°C or lower.

[0042] When rough polishing is performed using the polishing composition of this embodiment, the flash point of the hydrophobic dispersion medium is 30° C. or higher and 100° C. or lower, but in one embodiment, it is preferably 40° C. or higher and 100° C. or lower, more preferably 50° C. or higher and 80° C. or lower, and even more preferably 60° C. or higher and 70° C. or lower. When finish polishing is performed using the polishing composition of this embodiment, the flash point of the hydrophobic dispersion medium is 30° C. or higher and 100° C. or lower, but in one embodiment, it is preferably 40° C. or higher and 100° C. or lower, more preferably 50° C. or higher and 75° C. or lower, and even more preferably 60° C. or higher and 70° C. or lower.

[0043] In one preferred embodiment of the present invention, the hydrophobic dispersion medium comprises at least two of the following organic solvents: The first organic solvent with a flash point of 10°C or higher and 45°C or lower A second organic solvent having a flash point of more than 45°C and not more than 65°C (preferably not less than 50°C and not more than 65°C). A third organic solvent with a flash point of more than 65°C and less than 100°C (preferably between 70°C and 90°C). - The fourth organic solvent has a flash point of 100°C or higher and 180°C or lower.

[0044] By combining two or more of the first to fourth organic solvents, a hydrophobic dispersion medium having a flash point (FPI flash point) of 30 to 100°C can be easily prepared. For example, in one embodiment, the hydrophobic dispersion medium can be obtained by mixing a first organic solvent (e.g., 5 to 15% by mass, based on the total mass of the hydrophobic dispersion medium) with a second organic solvent (e.g., 85 to 95% by mass, based on the total mass of the hydrophobic dispersion medium). In another embodiment, the hydrophobic dispersion medium can be obtained by mixing a second organic solvent (e.g., 70 to 90% by mass, based on the total mass of the hydrophobic dispersion medium) with a fourth organic solvent (e.g., 10 to 30% by mass, based on the total mass of the hydrophobic dispersion medium). In yet another embodiment, the hydrophobic dispersion medium can be obtained by mixing a third organic solvent (e.g., 70% by mass to 90% by mass, based on the total mass of the hydrophobic dispersion medium) and a fourth organic solvent (e.g., 10% by mass to 30% by mass, based on the total mass of the hydrophobic dispersion medium). In yet another embodiment, the hydrophobic dispersion medium can be obtained by mixing a first organic solvent (e.g., 5% by mass to 15% by mass, based on the total mass of the hydrophobic dispersion medium), a second organic solvent (e.g., 55% by mass to 85% by mass, based on the total mass of the hydrophobic dispersion medium), and a fourth organic solvent (e.g., 10% by mass to 30% by mass, based on the total mass of the hydrophobic dispersion medium).

[0045] In one embodiment, the first organic solvent is preferably an organic solvent containing one or more selected from isoparaffinic hydrocarbons and normal paraffinic hydrocarbons. In one embodiment, the second organic solvent is preferably an organic solvent containing isoparaffinic hydrocarbons. In one embodiment, the third organic solvent is preferably an organic solvent containing one or more selected from isoparaffinic hydrocarbons and naphthenic hydrocarbons. In one embodiment, the fourth organic solvent is preferably an isoparaffinic hydrocarbon solvent. In one embodiment, the fourth organic solvent is preferably an isoparaffinic hydrocarbon solvent. In one embodiment, the fourth organic solvent is preferably an isoparaffinic hydrocarbon solvent. In one embodiment, the fourth organic solvent is preferably an organic solvent containing one or more selected from isoparaffinic hydrocarbons and normal paraffinic hydrocarbons.

[0046] In one embodiment of the present invention, the hydrophobic dispersion medium has a vapor pressure (20°C) of 0.004 kPa or more and 2 kPa or less. In one embodiment of the present invention, when the flash point of the hydrophobic dispersion medium is 30°C or more and 100°C or less, the vapor pressure (20°C) is preferably 0.004 kPa or more and 2 kPa or less. Also, in one embodiment of the present invention, the hydrophobic dispersion medium preferably has a vapor pressure (20°C) of 0.004 kPa or more, more preferably 0.005 kPa or more, and even more preferably 0.010 kPa or more. The vapor pressure of a hydrophobic dispersion medium indicates its ease of volatilization. The higher the vapor pressure, the easier it is to volatilize, and the lower the vapor pressure, the less likely it is to volatilize. Generally, the higher the temperature, the higher the vapor pressure, and the lower the temperature, the lower the vapor pressure. However, the magnitude relationship between vapor pressures at a given temperature does not change significantly even with changes in temperature. In other words, the ease of volatilization of a hydrophobic dispersion medium at a constant temperature is related to the vapor pressure of the hydrophobic dispersion medium. By setting the vapor pressure (20°C) of the hydrophobic dispersion medium within the above range, the abrasive grains and the amount of hydrophobic dispersion medium at the interface between the workpiece and the buff during polishing are optimally mixed, resulting in good abrasive grain processing power and good post-polishing cleanability. A vapor pressure (20°C) of 0.004 kPa or higher can prevent excessive abrasive grains and the amount of hydrophobic dispersion medium at the interface between the workpiece and the buff during polishing, which can prevent the abrasive grains from processing the coating film sufficiently and thus poor post-polishing cleanability. Regarding the upper limit of the vapor pressure (20°C), excessive volatilization of the hydrophobic dispersion medium can result in a shortage of organic solvent during polishing, potentially making it impossible to process with the abrasive grains. Therefore, the vapor pressure (20°C) of the hydrophobic dispersion medium is preferably 2 kPa or less, more preferably 1.8 kPa or less, even more preferably 1.5 kPa or less, and particularly preferably 1.4 kPa or less.

[0047] In one embodiment of the present invention, the vapor pressure of the hydrophobic dispersion medium (at 20°C) is 0.01 kPa or more and 1.0 kPa or less. Also, in one embodiment of the present invention, the vapor pressure of the hydrophobic dispersion medium (at 20°C) is 0.02 kPa or more and 0.5 kPa or less.

[0048] In the present invention, the vapor pressure refers to the vapor pressure of only one hydrophobic dispersion medium when only one type is used. When two or more hydrophobic dispersion mediums are mixed, the partial vapor pressure of each hydrophobic dispersion medium can be estimated using Raoult's law. It is known that the vapor pressure can be estimated by summing the partial pressures of the mixed vapor pressure in the mixed state. In the present invention, the mixed vapor pressure refers to the sum of the partial pressures of the mixed hydrophobic dispersion mediums. Specifically, when solvent A, which has a vapor pressure of 1 kPa and a molecular weight of 100, is mixed with solvent B, which has a vapor pressure of 0.5 kPa and a molecular weight of 200, in a weight ratio of 1:2, the molar ratio is 1:1 (molar ratio of 0.5:0.5), so the mixed vapor pressure is 1 kPa × 0.5 + 0.5 kPa × 0.5 = 0.75 kPa. The molecular weight of an organic solvent refers to its average molecular weight, which may be disclosed by the raw material manufacturer. If not disclosed, it can be estimated from the central carbon number information of the hydrocarbons that make up the organic solvent. Another indicator of volatility is the boiling point. There is a correlation between vapor pressure and boiling point, and the higher the vapor pressure, the lower the boiling point. Note that if the vapor pressure (20°C) is 0.001 kPa or less, it is treated as 0.001 kPa when calculating the mixed vapor pressure.

[0049] In one embodiment of the present invention, the hydrophobic dispersion medium has a flash point of 30° C. or higher and 100° C. or lower and a vapor pressure (20° C.) of 0.004 kPa or higher and 2 kPa or lower. When the hydrophobic dispersion medium has the above-mentioned configuration, the effects of the present invention are more pronounced.

[0050] In the present invention, when the hydrophobic dispersion medium is composed of two or more organic solvents, the average molecular weight of the organic solvents is preferably 120 to 350, more preferably 140 to 300, even more preferably 150 to 290, and particularly preferably 160 to 270.

[0051] In the present invention, when the hydrophobic dispersion medium is composed of two or more organic solvents, the vapor pressure (20°C) of the organic solvents is not particularly limited as long as the vapor pressure can be adjusted to 0.004 kPa or more and 2 kPa or less when mixed, and for example, the vapor pressure (20°C) of the organic solvents may be 0.001 kPa or less (in this case, as described above, the vapor pressure is calculated assuming that the vapor pressure is 0.001 kPa). When the hydrophobic dispersion medium is composed of two or more organic solvents, the vapor pressure (20°C) of the organic solvents is preferably 3 kPa or less, more preferably 2.5 kPa or less.

[0052] In one preferred embodiment of the present invention, the hydrophobic dispersion medium comprises at least two of the following organic solvents: - Fifth organic solvent with a vapor pressure (20°C) of 0.01 kPa or more and 0.1 kPa or less - The sixth organic solvent with a vapor pressure (20°C) of 0.001 kPa or less.

[0053] By combining two or more of the fifth and sixth organic solvents, a hydrophobic dispersion medium having a vapor pressure (20°C) of 0.004 kPa to 2 kPa can be easily prepared. For example, in one embodiment, the hydrophobic dispersion medium can be obtained by mixing the fifth organic solvent (e.g., 60% to 95% by mass, preferably 70% to 90% by mass, based on the total mass of the hydrophobic dispersion medium) with the sixth organic solvent (e.g., 5% to 40% by mass, preferably 10% to 30% by mass, based on the total mass of the hydrophobic dispersion medium).

[0054] In one embodiment, the fifth organic solvent is preferably an organic solvent containing one or more selected from isoparaffinic hydrocarbons and naphthenic hydrocarbons, and the sixth organic solvent is preferably an organic solvent containing normal paraffinic hydrocarbons.

[0055] In one preferred embodiment of the present invention, the hydrophobic dispersion medium comprises at least two of the following organic solvents: - The seventh organic solvent whose vapor pressure (at 20°C) is more than 0.001 kPa but less than 0.01 kPa An eighth organic solvent having a vapor pressure (20°C) of more than 0.1 kPa but not more than 3 kPa (preferably 1.0 kPa or more but not more than 2.5 kPa).

[0056] By combining two or more of the seventh and eighth organic solvents, a hydrophobic dispersion medium having a vapor pressure (20°C) of 0.004 kPa to 2 kPa can be easily prepared. For example, in one embodiment, the hydrophobic dispersion medium can be obtained by mixing the seventh organic solvent (e.g., 60% to 98% by mass, preferably 70% to 95% by mass, based on the total mass of the hydrophobic dispersion medium) with the eighth organic solvent (e.g., 2% to 40% by mass, preferably 5% to 30% by mass, based on the total mass of the hydrophobic dispersion medium).

[0057] In one embodiment, the seventh organic solvent is preferably an organic solvent containing an isoparaffinic hydrocarbon, and the eighth organic solvent is preferably an organic solvent containing one or more selected from isoparaffinic hydrocarbons and normal paraffinic hydrocarbons.

[0058] In a preferred embodiment of the present invention, the hydrophobic dispersion medium can be obtained by mixing the following organic solvents: A hydrophobic dispersion medium containing a sixth organic solvent (for example, 2% by mass or more and 40% by mass or less, preferably 5% by mass or more and 30% by mass or less, based on the total mass of the hydrophobic dispersion medium) and a seventh organic solvent (for example, 60% by mass or more and 98% by mass or less, preferably 70% by mass or more and 95% by mass or less, based on the total mass of the hydrophobic dispersion medium). A hydrophobic dispersion medium containing a sixth organic solvent (for example, 2% by mass or more and 40% by mass or less, preferably 5% by mass or more and 30% by mass or less, based on the total mass of the hydrophobic dispersion medium) and an eighth organic solvent (for example, 60% by mass or more and 98% by mass or less, preferably 70% by mass or more and 95% by mass or less, based on the total mass of the hydrophobic dispersion medium). A hydrophobic dispersion medium comprising a fifth organic solvent (e.g., 60% by mass or more and 98% by mass or less, preferably 65% ​​by mass or more and 95% by mass or less, based on the total mass of the hydrophobic dispersion medium) and an eighth organic solvent (e.g., 2% by mass or more and 40% by mass or less, preferably 5% by mass or more and 35% by mass or less, based on the total mass of the hydrophobic dispersion medium).

[0059] In a preferred embodiment of the present invention, the hydrophobic dispersion medium contains isoparaffinic hydrocarbons. In one embodiment, the isoparaffinic hydrocarbons are contained in the hydrophobic dispersion medium in an amount of 50 mass% or more, based on the total mass of the hydrophobic dispersion medium. In one embodiment, the isoparaffinic hydrocarbons are contained in the hydrophobic dispersion medium in an amount of preferably 55 mass% or more, more preferably 60 mass% or more, even more preferably 65 mass% or more, particularly preferably 70 mass% or more, and most preferably 75 mass% or more, based on the total mass of the hydrophobic dispersion medium. The upper limit of the isoparaffinic hydrocarbon content in the hydrophobic dispersion medium may be 100 mass%, or in one embodiment, may be 99 mass% or less, 98 mass% or less, or 97 mass% or less.

[0060] In one embodiment, the hydrophobic dispersion medium contains isoparaffinic hydrocarbons and normal paraffinic hydrocarbons. In this case, the isoparaffinic hydrocarbons are contained in the hydrophobic dispersion medium at a content of preferably 40% by mass to 98% by mass, more preferably 50% by mass to 97% by mass, even more preferably 60% by mass to 96% by mass, particularly preferably 65% ​​by mass to 95% by mass, and most preferably 70% by mass to 93% by mass, based on the total mass of the hydrophobic dispersion medium. Furthermore, the normal paraffinic hydrocarbons are contained in the hydrophobic dispersion medium at a content of preferably 2% by mass to 60% by mass, more preferably 3% by mass to 50% by mass, even more preferably 4% by mass to 40% by mass, particularly preferably 5% by mass to 35% by mass, and most preferably 7% by mass to 30% by mass, based on the total mass of the hydrophobic dispersion medium.

[0061] In one embodiment, the hydrophobic dispersion medium contains isoparaffinic hydrocarbons and naphthenic hydrocarbons. In this case, the isoparaffinic hydrocarbons are contained in the hydrophobic dispersion medium at a content of preferably 5% by mass to 80% by mass, more preferably 10% by mass to 75% by mass, even more preferably 15% by mass to 70% by mass, particularly preferably 20% by mass to 60% by mass, and most preferably 25% by mass to 50% by mass. Furthermore, the naphthenic hydrocarbons are contained in the hydrophobic dispersion medium at a content of preferably 2% by mass to 95% by mass, more preferably 25% by mass to 90% by mass, even more preferably 30% by mass to 85% by mass, particularly preferably 40% by mass to 80% by mass, and most preferably 50% by mass to 75% by mass. In one embodiment, the isoparaffinic hydrocarbons are preferably contained in the hydrophobic dispersion medium at 40% by mass or more and 97% by mass or less, more preferably 50% by mass or more and 95% by mass or less, even more preferably 60% by mass or more and 94% by mass or less, particularly preferably 65% ​​by mass or more and 92% by mass or less, and most preferably 70% by mass or more and 90% by mass or less, based on the total mass of the hydrophobic dispersion medium. The naphthenic hydrocarbons are preferably contained in the hydrophobic dispersion medium at 3% by mass or more and 60% by mass or less, more preferably 5% by mass or more and 50% by mass or less, even more preferably 6% by mass or more and 40% by mass or less, particularly preferably 8% by mass or more and 35% by mass or less, and most preferably 10% by mass or more and 30% by mass or less.

[0062] In one embodiment, the hydrophobic dispersion medium contains normal paraffinic hydrocarbons and naphthenic hydrocarbons. In this case, the normal paraffinic hydrocarbons are contained in the hydrophobic dispersion medium at a content of preferably 40% by mass to 97% by mass, more preferably 50% by mass to 95% by mass, even more preferably 60% by mass to 94% by mass, particularly preferably 65% ​​by mass to 92% by mass, and most preferably 70% by mass to 90% by mass, based on the total mass of the hydrophobic dispersion medium. The naphthenic hydrocarbons are contained in the hydrophobic dispersion medium at a content of preferably 3% by mass to 60% by mass, more preferably 5% by mass to 50% by mass, even more preferably 6% by mass to 40% by mass, particularly preferably 8% by mass to 35% by mass, and most preferably 10% by mass to 30% by mass, based on the total mass of the hydrophobic dispersion medium.

[0063] Benzene-based organic solvents and halogen-based organic solvents, which are known as organic solvents, are known to be highly harmful to the human body. Benzene-based organic solvents and halogen-based organic solvents are well-suited to painted surfaces, making it easy to control the amount of polishing composition present at the interface between the buff and the painted surface. However, polishing of painted surfaces, such as automobiles, is often performed manually, raising concerns about the harm to the polishing worker, and it is desirable to avoid the use of such organic solvents. For example, Japanese laws and regulations, such as the Organic Solvent Poisoning Prevention Regulations, require the use environment, wearing of protective equipment, and management of the work environment. Benzene-based solvents refer to aromatic hydrocarbon solvents. Benzene-based solvents include toluene, xylene, trimethylbenzene, ethylbenzene, naphthalene, etc., and a representative organic solvent containing benzene-based organic solvents is mineral spirits. Halogen-based organic solvents refer to halogen-substituted hydrocarbons. Representative examples of halogen-based organic solvents include dichloroethane, trichloroethylene, tetrachloroethylene, etc.

[0064] For the above reasons, in the present invention, it is preferable that the hydrophobic dispersion medium contains as little benzene-based organic solvents and halogen-based organic solvents as possible. That is, the upper limit of the content of benzene-based organic solvents and halogen-based organic solvents in the hydrophobic dispersion medium (the total amount of benzene-based organic solvents and halogen-based organic solvents) is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, particularly preferably 0.7% by mass or less, and most preferably 0.5% by mass or less, based on the total mass of the hydrophobic dispersion medium. The lower limit of the content of benzene-based organic solvents and halogen-based organic solvents is 0% by mass.

[0065] The lower limit of the content of the hydrophobic dispersion medium in the polishing composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 5% by mass or more, particularly preferably 10% by mass or more, and most preferably 15% by mass or more, based on the total mass of the polishing composition.The upper limit of the content of the hydrophobic dispersion medium in the polishing composition is preferably 60% by mass or less, more preferably 55% by mass or less, even more preferably 50% by mass or less, particularly preferably 45% by mass or less, and most preferably 40% by mass or less, based on the total mass of the polishing composition.That is, the content of the hydrophobic dispersion medium in the polishing composition is preferably 0.5% by mass or more and 60% by mass or less, more preferably 1% by mass or more and 55% by mass or less, even more preferably 5% by mass or more and 50% by mass or less, particularly preferably 10% by mass or more and 45% by mass or less, and most preferably 15% by mass or more and 40% by mass or less, based on the total mass of the polishing composition. In a preferred embodiment of the present invention, the content of the hydrophobic dispersion medium is 15% by mass or more and 40% by mass or less, based on the total mass of the polishing composition. By having the content of the hydrophobic dispersion medium in this range, the processing power is improved, and the object to be polished can be polished well in both rough polishing and finish polishing.

[0066] In the polishing composition according to this embodiment, the volume ratio of the hydrophobic dispersion medium to water (hydrophobic dispersion medium / water) may be, for example, less than 1, 0.7 or less, 0.5 or less, 0.3 or less, or 0.1 or less. The volume ratio of the hydrophobic dispersion medium to water (hydrophobic dispersion medium / water) may be 1 or more, 1.5 or more, 2 or more, 3 or more, 5 or more, or 10 or more. The emulsion type of the polishing composition of the present invention may be an oil-in-water (O / W) emulsion or a water-in-oil (W / O) emulsion. When the volume ratio of the hydrophobic dispersion medium to water (hydrophobic dispersion medium / water) is small (for example, less than 1), the polishing composition is likely to be an oil-in-water (O / W) emulsion. Furthermore, when the volume ratio of the hydrophobic dispersion medium to water (hydrophobic dispersion medium / water) is large (for example, 1 or more), the polishing composition tends to become a water-in-oil (W / O) emulsion.

[0067] [Surfactants] The polishing composition according to this embodiment preferably contains a surfactant for dispersing or emulsifying a hydrophobic dispersion medium or water. The surfactant also improves the efficiency of cleaning the polished surface after polishing by imparting hydrophilicity to the polished surface, thereby preventing the adhesion of dirt to the polished surface.

[0068] That is, in one embodiment, the polishing composition of the present invention is a polishing composition comprising abrasive grains, water, a hydrophobic dispersion medium, and a surfactant, wherein the hydrophobic dispersion medium comprises at least one selected from the group consisting of normal paraffin hydrocarbons, isoparaffin hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons, and has a flash point of 30°C or higher and 100°C or lower.

[0069] The surfactant contained in the polishing composition of the present invention is one or more selected from the group consisting of anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. Of these, nonionic surfactants are preferred as the surfactant contained in the polishing composition. These surfactants may be used alone or in combination of two or more.

[0070] Examples of anionic surfactants include polyoxyethylene alkyl ether acetates, polyoxyethylene alkyl sulfates, alkyl sulfates, polyoxyethylene alkyl ether sulfates, alkyl ether sulfates, alkylbenzenesulfonic acids, alkyl phosphates, polyoxyethylene alkyl phosphates, polyoxyethylene sulfosuccinic acids, alkyl sulfosuccinic acids, alkylnaphthalenesulfonic acids, alkyldiphenyletherdisulfonic acids, and salts thereof.

[0071] Examples of cationic surfactants include alkyltrimethylammonium salts, alkyldimethylammonium salts, alkylbenzyldimethylammonium salts, and alkylamine salts.

[0072] Examples of amphoteric surfactants include alkyl betaines and alkyl amine oxides.

[0073] Examples of nonionic surfactants include polyoxyalkylene alkyl ethers such as polyoxyethylene alkyl ethers, sorbitan fatty acid esters, glycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkylamines, and alkylalkanolamides.

[0074] When the hydrophobic dispersion medium in the polishing composition of the present invention contains an isoparaffinic hydrocarbon, the surfactant is preferably a polyoxyalkylene alkyl ether (HLB=10-14) from the viewpoint of emulsion stability. Here, the HLB (Hydrophilic-Lipophilic Balance) value represents the degree of affinity of a surfactant for water and oil (a water-insoluble organic compound). Examples of polyoxyalkylene alkyl ethers include alkyl ethers having 10 to 20 carbon atoms to which polyoxyethylene is added, such as polyoxyethylene lauryl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene octyldodecyl ether. The number of moles of polyoxyethylene added to the polyoxyalkylene alkyl ether may be such that the HLB is 10 to 14.

[0075] The content of surfactant in the polishing composition is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, based on the total mass of the polishing composition.Furthermore, the content of surfactant in the polishing composition is preferably 3.0 mass% or less, more preferably 2.0 mass% or less, based on the total mass of the polishing composition.When the content of surfactant is within the above range, the stability of the emulsion in the polishing composition is improved.

[0076] [Thickener] Examples of thickeners include synthetic thickeners such as polyacrylic acid, sodium polyacrylate (e.g., fully neutralized, partially neutralized, and associated alkali-soluble polyacrylic acid (acrylic polymer)), acrylic compounds, and urethane compounds; cellulose-based thickeners (semi-synthetic thickeners) such as carboxymethyl cellulose and carboxyethyl cellulose; and natural thickeners such as agar, carrageenan, layered silicate compounds, xanthan gum, and gum arabic. When associated alkali-soluble polyacrylic acid is used, polyacrylic acid is used in combination with an alkali. Examples of alkalis include inorganic alkalis such as sodium hydroxide, potassium hydroxide, and ammonia, and organic alkalis such as triethanolamine. The addition of an alkali allows polyacrylic acid to exhibit a thickening effect. The thickener may be a Newtonian fluid or a non-Newtonian fluid. The content of the thickener in the polishing composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, based on the total mass of the polishing composition. The content of the thickener in the polishing composition is preferably 3.0 mass % or less, more preferably 2.0 mass % or less, based on the total mass of the polishing composition. When the content of the additive is within the above range, the viscosity of the polishing composition is improved, and the polishing composition can be prevented from dripping on vertical surfaces such as the body of an automobile door.

[0077] [Additives] The polishing composition according to this embodiment preferably contains additives other than the above-mentioned components.Specific examples of the additives include oils, emulsion stabilizers, polymeric materials, pH adjusters, etc.The additives may be used alone or in combination of two or more.By adding the additives, the stability of the emulsion is improved.

[0078] Examples of oils include synthetic oils such as α-olefin oligomers, polyol esters, phosphate esters, and silicone oils; vegetable oils such as castor oil, soybean oil, palm oil, linseed oil, cottonseed oil, rapeseed oil, tung oil, and olive oil; and animal oils such as beef tallow and lanolin.

[0079] Examples of emulsion stabilizers include polyhydric alcohols such as glycerin, ethylene glycol, and propylene glycol, and fatty alcohols such as cetyl alcohol and stearyl alcohol.

[0080] The content of additives in the polishing composition is preferably 0.1 mass% or more, more preferably 1.0 mass% or more.The content of additives in the polishing composition is preferably 12.0 mass% or less, more preferably 8.0 mass% or less.When the content of additives is within the above range, the stability of emulsion in the polishing composition is improved.

[0081] [pH of polishing composition] The polishing composition of this embodiment can be adjusted in pH by adding, but not limited to, an acid or its salt, or a base or its salt, as described below. In one embodiment, the pH of the polishing composition is preferably from 4 to 12, more preferably from 5 to 11, even more preferably from 6 to 10, and particularly preferably from 7 to 10.

[0082] [Acid or its salt] The polishing composition of this embodiment may contain an acid or a salt thereof as a pH adjuster.

[0083] The acid may be either an inorganic acid or an organic acid. Examples of inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, and phosphoric acid. Examples of organic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, lactic acid, diglycolic acid, 2-furancarboxylic acid, 2,5-furandicarboxylic acid, 3-furancarboxylic acid, 2-tetrahydrofurancarboxylic acid, methoxyacetic acid, methoxyphenylacetic acid, phenoxyacetic acid, methanesulfonic acid, ethanesulfonic acid, sulfosuccinic acid, benzenesulfonic acid, toluenesulfonic acid, phenylphosphonic acid, and hydroxyethane-1,1-diphosphonic acid. Examples of salts include Group 1 element salts, Group 2 element salts, aluminum salts, ammonium salts, amine salts, and quaternary ammonium salts. These acids or salts can be used alone or in combination. Among these, nitric acid and citric acid are preferred.

[0084] [Base or its salt] The polishing composition of this embodiment may contain a base or its salt as a pH adjuster. Examples of the base or its salt include amines such as aliphatic amines and aromatic amines, organic bases such as quaternary ammonium hydroxide, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, hydroxides of Group 2 elements such as magnesium hydroxide and calcium hydroxide, and ammonia.

[0085] [Other ingredients] The polishing composition of this embodiment may further contain other components, as necessary, such as an oxidizing agent that oxidizes the surface of the object to be polished, a water-soluble polymer that acts on the surface of the object to be polished or the surface of the abrasive grains, an anticorrosive or chelating agent that suppresses corrosion of the object to be polished, an antiseptic agent having other functions, an antifungal agent, or a polymer material.

[0086] Examples of the oxidizing agent include hydrogen peroxide, peracetic acid, percarbonate, urea peroxide, perchlorate, and persulfate.

[0087] Examples of water-soluble polymers include polysulfonic acids such as polyphosphonic acid and polystyrene sulfonic acid, polysaccharides such as xanthan gum and sodium alginate, cellulose derivatives such as hydroxyethyl cellulose, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, alkylol ammonium salts, polyoxyethylene alkylphenyl ether, sorbitan monooleate, oxyalkylene polymers having one or more types of oxyalkylene units, etc. Salts of the above compounds can also be suitably used as water-soluble polymers.

[0088] Examples of the anticorrosive agent include amines, pyridines, tetraphenylphosphonium salts, benzotriazoles, triazoles, tetrazoles, and benzoic acid. Examples of the chelating agent include carboxylic acid chelating agents such as gluconic acid; amine chelating agents such as ethylenediamine, diethylenetriamine, and trimethyltetraamine; polyaminopolycarboxylic chelating agents such as ethylenediaminetetraacetic acid, nitrilotriacetic acid, hydroxyethylethylenediaminetriacetic acid, triethylenetetraminehexaacetic acid, and diethylenetriaminepentaacetic acid; organic phosphonic acid chelating agents such as 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri(methylenephosphonic acid), ethylenediaminetetrakis(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, methanehydroxyphosphonic acid, and 1-phosphonobutane-2,3,4-tricarboxylic acid; phenol derivatives; and 1,3-diketones.

[0089] Examples of preservatives include sodium hypochlorite, etc. Examples of antifungal agents include oxazolines such as oxazolidine-2,5-dione, etc.

[0090] [Method for producing polishing composition] The method for producing the polishing composition of the present embodiment includes the steps of: preparing a hydrophobic dispersion medium containing at least one selected from the group consisting of normal paraffin hydrocarbons, isoparaffin hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons, and having a vapor pressure at 20°C of 0.004 kPa or more and 2 kPa or less and / or a flash point of 30°C or more and 100°C or less; mixing the hydrophobic dispersion medium, water, and abrasive grains; By such a production method, a polishing composition that can exhibit the desired effects of the present invention can be produced. That is, the present invention also provides a method for producing a polishing composition.

[0091] When the hydrophobic dispersion medium contains two or more compounds, in the method for producing a polishing composition of this embodiment, the step of preparing the hydrophobic dispersion medium includes a step of mixing two or more organic solvents selected from the group consisting of normal paraffin hydrocarbons, isoparaffin hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons, and adjusting the vapor pressure (20°C) to 0.004 kPa or more and 2 kPa or less, and / or adjusting the flash point to 30°C or more and 100°C or less, to obtain the hydrophobic dispersion medium. The method for mixing two or more organic solvents and adjusting the vapor pressure (20°C) of the hydrophobic dispersion medium to 0.004 kPa or more and 2 kPa or less and / or the flash point to 30°C or more and 100°C or less is not particularly limited. For example, when adjusting the flash point of the hydrophobic dispersion medium to 30°C or more and 100°C or less, the amount of each organic solvent is calculated based on the flash point of each organic solvent and the FPI flash point described above so that the resulting hydrophobic dispersion medium has a flash point of 30°C or more and 100°C or less, and then mixed. The manner in which two or more organic solvents are mixed can be the same as that described in the explanation for calculating the FPI flash point. For example, when adjusting the vapor pressure (20°C) of the hydrophobic dispersion medium to 0.004 kPa or more and 2 kPa or less, the amount of each organic solvent is calculated based on the vapor pressure of each organic solvent so that the resulting hydrophobic dispersion medium has a vapor pressure (20°C) of 0.004 kPa or more and 2 kPa or less, and then mixed.

[0092] When the polishing composition of the present invention contains surfactant, it is preferred to mix hydrophobic dispersion medium and surfactant in advance, then mix with water and abrasive grains.In addition, when the polishing composition of the present invention contains hydrophilic components such as thickener, emulsion stabilizer, etc., it is preferred to mix water and hydrophilic components in advance, then mix with hydrophobic dispersion medium and abrasive grains.After mixing hydrophobic dispersion medium, water and abrasive grains, if necessary, by stirring and mixing other components such as pH adjuster, the polishing composition of this embodiment can be obtained.

[0093] In each of the above steps, the temperature at which the components are mixed is not particularly limited, but is preferably 10° C. or higher and 40° C. or lower. There is also no particular limit to the mixing time.

[0094] [Polished object] The object to be polished in this embodiment is not particularly limited, but preferably contains at least one material selected from the group consisting of alloy materials, resin materials, metals, semi-metals, metal oxides, metal carbides, metal nitrides, semi-metal oxides, semi-metal carbides, semi-metal nitrides, and glass materials, and may also be a composite material of these materials. In particular, resin materials used for painted surfaces such as automobile bodies are preferred.

[0095] In one embodiment, the polishing composition of the present invention is used in finish polishing of a resin material having a pencil hardness of F or less. That is, the object to be polished with the polishing composition of the present invention is preferably a resin material having a pencil hardness of F or less.

[0096] Here, an alloy is a compound in which one metal element shares one or more metal elements or nonmetallic elements such as carbon, nitrogen, or silicon. It is manufactured with the aim of improving properties such as mechanical strength, chemical resistance, corrosion resistance, and heat resistance compared to pure metals. Among these, aluminum alloys, due to their light weight and excellent strength, are used in a variety of applications, including structural materials such as building materials and containers, transportation equipment such as automobiles, ships, and aircraft, as well as various electrical appliances and electronic components. Titanium alloys, due to their light weight and excellent corrosion resistance, are widely used in precision instruments, decorative items, tools, sporting goods, medical components, and the like. Iron-based alloys, such as stainless steel and nickel alloys, have excellent corrosion resistance and are used in a variety of applications, including structural materials and transportation equipment, tools, machinery, and cooking utensils. Copper alloys, due to their excellent electrical conductivity, thermal conductivity, and corrosion resistance, as well as their excellent workability and beautiful finish, are widely used in decorative items, tableware, musical instruments, electrical components, and the like. Furthermore, resin-containing materials have recently been used in the above-mentioned applications.

[0097] Hereinafter, alloy materials, resin materials, metals, semi-metals, and materials such as oxides, carbides, and nitrides thereof, as well as glass materials will be described.

[0098] [Alloy material] The alloy material contains a metal species that is the main component and a metal species that is different from the main component.

[0099] Alloy materials are named based on the metal species that constitutes the main component. Examples of alloy materials include aluminum alloys, iron alloys, titanium alloys, nickel alloys, and copper alloys. These alloy materials may be used alone or in combination of two or more. Among these, it is preferable to use at least one selected from the group consisting of aluminum alloys and iron alloys. Furthermore, alloy materials in which the difference in Vickers hardness (HV) between the metal species that constitutes the main component and a metal species other than the main component is 5 or more are preferred.

[0100] The aluminum alloy contains aluminum as the main component, and preferably contains at least one metal selected from the group consisting of magnesium, silicon, copper, zinc, manganese, chromium, and iron as a metal species other than the main component. The lower limit of the content of the metal species other than the main component in the aluminum alloy is not particularly limited, but is preferably 0.1 mass% or more with respect to the entire aluminum alloy. Furthermore, the upper limit of the content of the metal species other than the main component in the aluminum alloy is not particularly limited, but is preferably 10 mass% or less with respect to the entire aluminum alloy.

[0101] Specific examples of aluminum alloys include Al-Cu and Al-Cu-Mg alloys with numbers in the 2000s, Al-Mn alloys with numbers in the 3000s, Al-Si alloys with numbers in the 4000s, Al-Mg alloys with numbers in the 5000s, Al-Mg-Si alloys with numbers in the 6000s, Al-Zn-Mg alloys with numbers in the 7000s, and Al-Fe-Mn alloys with numbers in the 8000s, as described in JIS H4000:2006.

[0102] The iron alloy contains iron as the main component, and preferably contains at least one metal selected from the group consisting of chromium, nickel, molybdenum, and manganese as a metal species other than the main component. The lower limit of the content of the metal species other than the main component in the iron alloy is not particularly limited, but is preferably 10% by mass or more based on the total iron alloy. The upper limit of the content of the metal species other than the main component in the iron alloy is not particularly limited, but is preferably 50% by mass or less based on the total iron alloy.

[0103] The iron alloy is preferably stainless steel. Specific examples of stainless steel include SUS201, SUS303, 303Se, SUS304, SUS304L, SUS304NI, SUS305, SUS305JI, SUS309S, SUS310S, SUS316, SUS316L, SUS321, SUS347, SUS384, SUSXM7, SUS303F, SUS303C, SUS430, SUS430F, SUS434, SUS410, SUS416, SUS420J1, SUS420J2, SUS420F, SUS420C, and SUS631J1, among others, according to the symbols of the types described in JIS G4303:2005.

[0104] Titanium alloys contain titanium as the main component and other metal species, such as aluminum, iron, and vanadium. The content of the metal species other than the main component in the titanium alloy is, for example, 3.5% by mass or more and 30% by mass or less of the total titanium alloy. Examples of titanium alloys include types 11 to 23, 50, 60, 61, and 80, among the types described in JISH4600:2012.

[0105] The nickel alloy contains nickel as the main component and at least one metal species selected from iron, chromium, molybdenum, and cobalt as a metal species other than the main component. The content of the metal species other than the main component in the nickel alloy is, for example, 20% by mass or more and 75% by mass or less of the total nickel alloy. Examples of nickel alloys include alloy numbers NCF600, 601, 625, 750, 800, 800H, 825, NW0276, 4400, 6002, and 6022 listed in JISH4551:2000.

[0106] Copper alloys contain copper as the main component and at least one metal selected from iron, lead, zinc, and tin as a different metal from the main component. The content of the different metal in the copper alloy is, for example, 3% by mass or more and 50% by mass or less of the total copper alloy. Examples of copper alloys include alloy numbers C2100, 2200, 2300, 2400, 2600, 2680, 2720, 2801, 3560, 3561, 3710, 3713, 4250, 4430, 4621, 4640, 6140, 6161, 6280, 6301, 7060, 7150, 1401, 2051, 6711, and 6712 in accordance with the JISH3100:2006 standard.

[0107] [Resin material] The type of resin material is not particularly limited, and may be either a thermosetting resin or a thermoplastic resin.

[0108] Examples of the thermosetting resin include epoxy resin, polyimide resin, phenol resin, amino resin, unsaturated polyester resin, thermosetting polyurethane resin, and melamine resin.

[0109] Examples of thermoplastic resins include polystyrene resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), (meth)acrylic resin (methacrylic and / or acrylic resin), organic acid vinyl ester resin or derivatives thereof, vinyl ether resin, halogen-containing resins such as polyvinyl chloride, polyvinylidene chloride, and polyvinylidene fluoride, olefin resins such as polyethylene and polypropylene, saturated polyester resins such as polycarbonate resin, polyethylene terephthalate, and polyethylene naphthalate, polyamide resin, thermoplastic polyurethane resin, polysulfone resin (polyethersulfone, polysulfone, etc.), polyphenylene ether resin (2,6-xylenol polymer, etc.), cellulose derivatives (cellulose esters, cellulose carbamates, cellulose ethers, etc.), and silicone resin (polydimethylsiloxane, polymethylphenylsiloxane, etc.).

[0110] The above resins can be used alone or in combination of two or more. Among these resins, thermoplastic resins are preferred from the viewpoint of impact resistance and weather resistance, and polycarbonate resins are more preferred.

[0111] The object to be polished containing a resin material may be, for example, in the form of a member (resin member) formed from the resin material, or in the form of a composite material having a resin coating film on the surface of a metal substrate or the like, and is not particularly limited. Examples of resins used in the coating film include thermosetting polyurethane resins and (meth)acrylic resins. The resin coating film may be a transparent clear coating film. In addition, the polishing composition of the present invention is preferably used for resin coating films having a pencil hardness of preferably H or less, more preferably F or less, as measured by the pencil method described in JIS K 5600-5-4 (1999).

[0112] The composite material having a resin coating film is not particularly limited, but an example thereof is a three-dimensional resin material.The applications of the three-dimensional resin material include, for example, automobile bodies, railway vehicles, aircraft, and resin components.The resin coating film coated on the surface of an automobile body has a large area and a curved surface, and the polishing composition of this embodiment is suitable for polishing the outer surface of such a resin coating film.

[0113] [Metals, semimetals, and their oxides, carbides, and nitrides] Examples of metals include aluminum, iron, zirconium, copper, nickel, gold, silver, bismuth, manganese, and zinc.

[0114] Examples of types of semimetals include Group IV semiconductors such as silicon (Si) and germanium (Ge), Group II-VI compound semiconductors such as zinc selenide (ZnSe), cadmium sulfide (CdS), and zinc oxide (ZnO), Group III-V compound semiconductors such as gallium arsenide (GaAs), indium phosphide (InP), and gallium nitride (GaN), Group IV compound semiconductors such as silicon carbide (SiC) and silicon germanium (SiGe), and chalcopyrite semiconductors such as copper-indium-selenium (CuInSe2).

[0115] It can also be suitably used for oxides, carbides, and nitrides of these materials.

[0116] [Glass Materials] Examples of glass materials include soda lime glass, quartz glass, tempered glass, crystallized glass, aluminosilicate glass, and glassy carbon.

[0117] [Polishing method] As described above, the polishing composition of this embodiment is suitable for polishing objects containing alloy materials, resin materials, metals, semi-metals, metal oxides, metal carbides, metal nitrides, semi-metal oxides, semi-metal carbides, semi-metal nitrides, or glass materials, as well as composite materials of these materials.

[0118] The polishing composition of this embodiment is suitable for polishing an object having a curved surface to be polished (for example, the painted surface of an automobile or other vehicle body). Thus, the present invention also provides a polishing method for polishing an object using the polishing composition of this embodiment. That is, the present invention provides a polishing method in which a painted surface is polished with a wool buff and / or a sponge buff using the polishing composition or the polishing composition obtained by the production method. According to one embodiment, a polishing method is provided in which a painted surface is polished with a wool buff using the polishing composition of this embodiment. According to another embodiment, a polishing method is provided in which a painted surface is polished with a sponge buff using the polishing composition of this embodiment.

[0119] A method for polishing a resin-coated surface will be described below as an example of the polishing method of this embodiment. The configuration of the polishing device used for polishing is not particularly limited, and general polishing devices such as a handheld polisher, a single-sided polisher, a double-sided polisher, or a lens polisher may be used, as well as the automatic polishing device shown in Figure 1 of International Publication No. 2019 / 066014 (the polishing pad 10 in Figure 1 corresponds to the polishing buff).

[0120] For example, the polishing method of this embodiment may be applied when an abrasive buff is attached to the tip of a hand polisher and a polishing worker manually operates the hand polisher to polish a resin-coated surface. The driving means for the hand polisher is not particularly limited, but generally, single action, double action, gear action, etc. are used, and double action is preferred for polishing coated members.

[0121] When polishing an object to be polished, such as an alloy material, using the polishing composition of this embodiment, the polishing can be performed using equipment and conditions commonly used for metal polishing. In a single-side polishing apparatus, a holder called a carrier is used to hold the object to be polished (preferably a substrate-like object to be polished), and one side of the object to be polished is polished by pressing a platen with an abrasive cloth attached to one side of the object to be polished and rotating the platen while supplying the polishing composition. In a double-side polishing apparatus, a holder called a carrier is used to hold the object to be polished, and while supplying the polishing composition from above, a platen with an abrasive cloth attached to the opposite side of the object to be polished is pressed against the opposite side of the object to be polished, and the two plates are rotated in relative directions to polish both sides of the object to be polished. At this time, polishing is performed by the physical action of friction between the polishing pad and the polishing composition and the object to be polished, and the chemical action of the polishing composition on the object to be polished.

[0122] The polishing load is an example of a polishing condition in the polishing method according to this embodiment. Generally, the higher the load, the higher the frictional force caused by the abrasive grains, and the improved mechanical processing force results in a higher polishing rate. The lower limit of the polishing load in the polishing method according to this embodiment is not particularly limited, but is preferably 10 g / cm. 2 It is preferable that the density is 18 g / cm or more. 2 As the polishing load increases, the mechanical processing characteristics improve, and the polishing rate increases. The upper limit of the polishing load is 1000 g / cm. 2 Preferably, it is 500 g / cm or less. 2 As the polishing load decreases, surface roughness of the polished surface is more suppressed.

[0123] Another polishing condition in the polishing method according to this embodiment is the linear velocity during polishing (linear polishing velocity). Generally, the linear velocity is affected by the rotation speed of the polishing pad, the rotation speed of the carrier, the size of the object to be polished, the number of objects to be polished, and other factors. A high linear velocity increases the frictional force acting on the object to be polished, making it more likely to be mechanically polished. Furthermore, friction can generate frictional heat, which can enhance the chemical action of the polishing composition. The lower limit of the linear polishing velocity in the polishing method according to this embodiment is not particularly limited, but is preferably 10 m / min or more, more preferably 20 m / min or more. The upper limit of the linear polishing velocity is preferably 1000 m / min or less, more preferably 500 m / min or less. Within this range, a sufficiently high polishing velocity can be obtained, and an appropriate frictional force can be applied to the object to be polished. That is, in this embodiment, the linear polishing velocity is preferably 10 m / min or more to 1000 m / min or less, more preferably 20 m / min or more to 500 m / min or less.

[0124] The polishing composition of this embodiment may be used in a process completed in one stage, or in one or more stages of a process having multiple polishing stages. For example, when used in a process having three polishing stages, it can be used in one or more stages of the first stage (rough polishing), the second stage (medium polishing), and the third stage (finish polishing).

[0125] When using the polishing composition of this embodiment to polish an object to be polished, the polishing composition that has been used for polishing once can be recovered and used again for polishing.As an example of the method for reusing the polishing composition, the polishing composition that is discharged from the polishing device can be recovered in a tank, and can be circulated back into the polishing device for use again.The recycling of the polishing composition is useful in that it can reduce the amount of the polishing composition that is discharged as waste liquid, thereby reducing environmental load, and it can reduce the amount of the polishing composition that is used, thereby reducing the manufacturing cost required for polishing the object to be polished.

[0126] When the polishing composition of this embodiment is recycled, some or all of the abrasive grains and other additives consumed or lost during polishing can be added as a composition adjuster during the recycling process. In this case, the composition adjuster may be a mixture of some or all of the abrasive grains and other additives in any desired ratio. By adding additional composition adjuster, the polishing composition is adjusted to a composition suitable for reuse, thereby maintaining favorable polishing. The concentrations of the abrasive grains and other additives contained in the composition adjuster are arbitrary and not particularly limited, but are preferably adjusted appropriately depending on the size of the circulation tank and the polishing conditions.

[0127] The polishing composition of this embodiment may be a one-component type or a multi-component type such as a two-component type. The polishing composition of this embodiment may also be prepared by diluting the stock solution of the polishing composition, for example, 10 times or more, with a diluent such as water or oil.

[0128] The polishing buff used in the polishing method using the polishing composition of this embodiment may be made of a material such as wool type, polyurethane type, foamed polyurethane type, nonwoven fabric type, or suede type. [Example]

[0129] The present invention will be described in more detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass," respectively. In the following examples, unless otherwise specified, the operations were carried out under the conditions of room temperature (20°C to 25°C) and relative humidity of 30% RH to 50% RH.

[0130] (Preparation of Polishing Compositions of Examples 1 to 11 and Comparative Examples 1 to 3) A hydrophobic dispersion medium solution was prepared by adding the amount of polyoxyalkylene alkyl ether (surfactant) shown in Table 1, having an HLB value of 13.3, to the type and amount of organic solvent shown in Table 1. Next, 0.95% by mass of a polyacrylic acid-based polymer (thickener) and 2.0% by mass of glycerin (emulsion stabilizer) were mixed with water, and the resulting solution was added to the hydrophobic dispersion medium solution and stirred at room temperature (25°C). Aluminum oxide was then added as abrasive grains in the amount shown in Table 1. To the resulting dispersion, 0.1% by mass of a preservative was added, and sodium hydroxide was added as an alkali to adjust the pH to 9.0, yielding polishing compositions of Examples 1 to 11 and Comparative Examples 1 to 3 as O / W emulsions. The water content is the remainder of the total amount of the above components, assuming the polishing composition to be 100% by mass.

[0131] In Table 1, "-" indicates that the organic solvent is not contained, and the content of each component in each polishing composition is the content relative to the total mass of the polishing composition, with the remainder being water (including sodium hydroxide). In Table 1, the "average particle size" of the abrasive grains (aluminum oxide) in each polishing composition represents the average secondary particle size, the "FPI-converted flash point" represents the flash point converted from the FPI (Flash Point Blend Index), and the "total content of benzene-based and halogen-based organic solvents" represents the total content of benzene-based and halogen-based organic solvents relative to the entire hydrophobic dispersion medium. Furthermore, the "mixed vapor pressure" in Tables 1 to 3 is the vapor pressure at 20°C.

[0132] The abrasive grains and organic solvents listed in Table 1 were as follows:

[0133] <Abrasive grain> The abrasive grains used were one of the following three types: Aluminum oxide: Alpha conversion rate 95%, average secondary particle size (D50) 0.6 μm Aluminum oxide: Alpha conversion rate 95%, average secondary particle size (D50) 1.4 μm Aluminum oxide: Alpha conversion rate 95%, average secondary particle diameter (D50) 2.6 μm.

[0134] The alpha phase ratio of the aluminum oxide particles was measured using an X-ray analyzer (Ultima-IV, manufactured by Rigaku Corporation), and commercially available alpha alumina single crystal particles (alpha phase ratio: 100%), which had been fired at a sufficiently high temperature and had undergone sufficient alpha phase transformation, were used as the reference material. The integrated intensity of the (113) diffraction line from X-ray diffraction measurements of the reference material and the target abrasive grains (aluminum oxide particles), was measured, and the alpha phase ratio of the target abrasive grains (aluminum oxide particles) was calculated from the ratio of the integrated intensity of the (113) diffraction line of the target abrasive grains to that of the reference material.

[0135] In addition, the average secondary particle diameter (D50) of each abrasive grain was measured by the laser diffraction / scattering method using a MicrotracMT3300EXII (Microtrac Bell Corporation).

[0136] <Organic solvents> One or more of the following organic solvents were used. Vapor pressure is the value at 20°C. Organic solvent 1: Synthetic hydrocarbons derived from mineral oil (mixture of isoparaffinic hydrocarbons and normal paraffinic hydrocarbons), flash point: 30°C (closed container method), total content of benzene-based organic solvents and halogenated organic solvents: 10% by mass or more, vapor pressure: 1.4 kPa (molecular weight: 128) Organic solvent 2: Synthetic hydrocarbon derived from mineral oil (isoparaffinic hydrocarbon), flash point: 63°C (closed container method), total content of benzene-based organic solvents and halogenated organic solvents: 0.5% by mass or less, vapor pressure: 0.05 kPa (molecular weight: 170) Organic solvent 3: Synthetic hydrocarbons derived from mineral oil (naphthenic hydrocarbons), flash point: 75°C (closed container method), total content of benzene-based organic solvents and halogenated organic solvents: 0.5% by mass or less, vapor pressure: 0.023 kPa (molecular weight: 170) Organic solvent 4: Synthetic hydrocarbon derived from mineral oil (isoparaffinic hydrocarbon), flash point: 86°C (closed container method), total content of benzene-based organic solvents and halogenated organic solvents: 0.5% by mass or less, vapor pressure: 0.006 kPa (molecular weight: 184) Organic solvent 5: Synthetic hydrocarbon derived from mineral oil (isoparaffinic hydrocarbon), flash point: 139°C (closed container method), total content of benzene-based organic solvents and halogenated organic solvents: 0.5% by mass or less, vapor pressure: 0.001 kPa or less (molecular weight: 226) Organic solvent 6: Synthetic hydrocarbon derived from mineral oil (normal paraffin hydrocarbon), flash point: 168°C (open method), total content of benzene-based organic solvents and halogenated organic solvents: 0.5% by mass or less, vapor pressure: 0.001 kPa or less (molecular weight: 268) (Polishing evaluation) Polishing was carried out under the following polishing conditions using the polishing compositions of Examples and Comparative Examples, and the processing power (removal amount) and cleaning properties were evaluated according to the following methods.

[0137] <Polishing conditions> The polishing machine used for polishing was a double action polisher LHR12E (manufactured by Rupes Co., Ltd.), and the specific polishing conditions were as follows:

[0138] (Test with wool buff) Buff: Wool buff (hair length: about 15 mm) Pressing load: 4kg Polisher rotation speed: 5300 rpm Polishing linear speed: 200m / min Polishing composition flow rate: 0.4 g / 15 seconds Polishing time: The time it takes to visually confirm the removal of the clear coating film after dry sanding with #3000 paper Polishing area: 300×400mm The object to be polished used was a composite material having a clear coating film made of synthetic resin paint on the surface of a steel plate, and the pencil hardness of the clear coating film was H.

[0139] (Evaluation of processing power) The state of elimination of scratches caused by dry sanding with #3000 sandpaper was visually confirmed, and the evaluation was made as follows based on the time taken for the scratches to disappear. [Evaluation criteria] A: Less than 150 seconds; Pass, particularly excellent B: Between 150 and 195 seconds; Pass C: 195 seconds or more: The processing time is too long, so it is rejected.

[0140] (Evaluation of cleaning ability) After polishing, the clear coating was wiped with water and then with a cloth (product name: 3M Finishing Wipe 5351, size 36 cm x 36 cm) to measure the time required to remove the residue on the coating. Specifically, the evaluation was performed as follows based on the time required for the abrasive grains and solution components to disappear visually (total time required for wiping with water and wiping with dry wipes). Note that if the remaining matter was removed with more force than usual even within the time required for the evaluation criteria below, the evaluation was lowered by one level. Specifically, when the polishing compositions of Examples 1 to 3 were used, the time required for the abrasive grains and solution components to disappear was within 20 seconds, but force was required to remove the remaining matter, so the evaluation was given a B rating. [Evaluation criteria] A: Less than 20 seconds; Pass, particularly excellent B: 20-40 seconds: Pass C: More than 40 seconds: Failed due to long wiping time.

[0141] (Evaluation results) Table 2 shows the evaluation results of polishing with a wool buff using the polishing compositions of Examples 1 to 11 and Comparative Examples 1 to 3.

[0142] [Evaluation of polishing with sponge buff] (Polishing evaluation) Polishing was carried out with a sponge buff under the following polishing conditions using the polishing compositions of Examples 1 to 7, 9 to 11 and Comparative Examples 1 to 3. After polishing, the processing power (polishing rate), cleanability, and surface condition (surface defects) were evaluated according to the following methods.

[0143] <Polishing conditions> The polishing machine used for polishing was a double action polisher LHR12E (manufactured by Rupes Co., Ltd.), and the specific polishing conditions were as follows:

[0144] (Test with sponge buff) Buff: Sponge buff Pressing load: 4kg Polisher rotation speed: 5300 rpm Polishing linear speed: 200m / min Polishing composition flow rate: 0.4 g / 45 seconds Polishing time: 45 seconds Polishing area: 300×400mm The object to be polished used was a composite material with a clear coating made of synthetic resin paint on the surface of a steel plate, and two types of clear coating were prepared: one with a pencil hardness of F and one with a pencil hardness of H.

[0145] When calculating the processing force, the measurement accuracy of the film thickness measuring device was taken into consideration, and the polishing time was changed to 3 minutes, and the calculation of the processing force was carried out.

[0146] (Evaluation of processing power) Using an electromagnetic induction film thickness measuring device, the film thickness of each film was measured before and after polishing. The removal amount (removal volume) was calculated from the difference in film thickness before and after polishing, and the removal rate was calculated from the removal amount. If the removal rate is 0.7 μm / min or more, it is considered to be acceptable, as it can remove scratches caused by car washes, etc.

[0147] (Evaluation of cleaning ability) After polishing, the clear coating was wiped with water and then with a dry cloth (product name: 3M Finishing Wipe 5351, size 36 cm x 36 cm) to measure the time it took to remove the residue from the coating. Specifically, the evaluation was performed as follows based on the time it took for the abrasive grains and solution components to disappear visually (total time for wiping with water and wiping with dry wipes). Note that if more force than normal was used to remove the residue even within the time specified in the evaluation criteria below, the evaluation was lowered by one level. [Evaluation criteria] A: Less than 20 seconds; Pass, particularly excellent B: 20 ​​seconds or more and 40 seconds or less; Pass C: More than 40 seconds: Failed due to long wiping time.

[0148] (presence or absence of adhesions) After polishing, the clear coating was wiped with water and then dry using a cloth (product name: 3M Finishing Wipe 5351, size 36 cm x 36 cm) to remove any residue on the coating, and then the presence or absence of any adhesion on the coating was visually confirmed and evaluated based on the following criteria. [Evaluation criteria] A: No adhesion; Pass, particularly excellent B: Some adhesion; Pass C: There is adhesion all over the surface; poor finish and unacceptable.

[0149] (Evaluation results) The evaluation results of polishing with a sponge buff using the polishing compositions of Examples 1 to 7, 9 to 11 and Comparative Examples 1 to 3 are shown in Table 3. In Table 3, the symbol "-" indicates that no evaluation was performed.

[0150] [Table 1]

[0151] [Table 2]

[0152] [Table 3]

[0153] As shown in Tables 2 and 3, when the polishing compositions of Examples 1 to 11 were used, it was found that excellent processing power was achieved in rough polishing and finish polishing, and the cleanability after polishing was also good.

[0154] This shows that the polishing composition containing a hydrophobic dispersion medium having a flash point within a specific range exhibits the effects of excellent processing power and good cleanability.

[0155] This application is based on Japanese Patent Application No. 2021-059448, filed on March 31, 2021, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A polishing composition comprising abrasive grains, water, and a hydrophobic dispersion medium, the hydrophobic dispersion medium contains at least two or more organic solvents selected from the group consisting of normal paraffin hydrocarbons, isoparaffin hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons, and has an FPI flash point of 30°C or higher and 100°C or lower; The hydrophobic dispersion medium comprises an organic solvent having a flash point of more than 45°C and not more than 65°C or more than 65°C and not more than 100°C, and an organic solvent having a flash point of 100°C or more and 180°C or less.

2. 2. The polishing composition according to claim 1, wherein the hydrophobic dispersion medium has a vapor pressure at 20°C of 0.004 kPa or more and 2 kPa or less.

3. A polishing composition comprising abrasive grains, water, and a hydrophobic dispersion medium, the hydrophobic dispersion medium contains at least two organic solvents selected from the group consisting of normal paraffin hydrocarbons, isoparaffin hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons, and has a vapor pressure at 20°C of 0.004 kPa or more and 2 kPa or less; The hydrophobic dispersion medium comprises an organic solvent having a vapor pressure of 0.01 kPa or more and 0.1 kPa or less, and an organic solvent having a vapor pressure of 0.001 kPa or less.

4. 4. The polishing composition according to claim 1, wherein the hydrophobic dispersion medium has an FPI flash point of 50° C. or higher and 80° C. or lower.

5. 5. The polishing composition according to claim 1, wherein the hydrophobic dispersion medium has an FPI flash point of 64° C. or higher and 74° C. or lower.

6. 6. The polishing composition according to claim 1, wherein the hydrophobic dispersion medium is contained in an amount of 15% by mass or more and 40% by mass or less based on the total mass of the polishing composition.

7. 7. The polishing composition according to claim 1, further comprising a surfactant.

8. 8. The polishing composition according to claim 1, wherein the abrasive grains are aluminum oxide.

9. 9. The polishing composition according to claim 8, wherein the aluminum oxide has an alpha conversion rate of 50% or more.

10. 10. The polishing composition according to claim 1, wherein the abrasive grains have an average secondary particle size of 0.05 μm or more and 10 μm or less.

11. 11. The polishing composition according to claim 1, wherein the abrasive grains are contained in an amount of 5% by mass or more and 30% by mass or less based on the total mass of the polishing composition.

12. The polishing composition according to any one of claims 1 to 11, which is used in finish polishing of a resin material having a pencil hardness of F or less.

13. preparing a hydrophobic dispersion medium containing at least two organic solvents selected from the group consisting of normal paraffin hydrocarbons, isoparaffin hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons, and having an FPI flash point of 30°C or higher and 100°C or lower; mixing the hydrophobic dispersion medium, water, and abrasive grains; Including, A method for producing a polishing composition, wherein the hydrophobic dispersion medium is obtained by mixing an organic solvent having a flash point of more than 45°C and not more than 65°C or an organic solvent having a flash point of more than 65°C and less than 100°C with an organic solvent having a flash point of 100°C or more and 180°C or less.

14. preparing a hydrophobic dispersion medium containing at least two organic solvents selected from the group consisting of normal paraffin hydrocarbons, isoparaffin hydrocarbons, naphthenic hydrocarbons, and terpene hydrocarbons, the hydrophobic dispersion medium having a vapor pressure of 0.004 kPa or more and 2 kPa or less at 20°C; mixing the hydrophobic dispersion medium, water, and abrasive grains; Including, The method for producing a polishing composition, wherein the hydrophobic dispersion medium is obtained by mixing an organic solvent having a vapor pressure of 0.01 kPa or more and 0.1 kPa or less with an organic solvent having a vapor pressure of 0.001 kPa or less.

15. A polishing method comprising polishing an object to be polished with the polishing composition according to any one of claims 1 to 12 or the polishing composition obtained by the production method according to claim 13 or 14.

16. 16. The polishing method according to claim 15, wherein the object to be polished includes at least one material selected from the group consisting of a resin material, an alloy material, and a glass material.

17. A polishing method comprising polishing a painted surface with a wool buff and / or a sponge buff using the polishing composition according to any one of claims 1 to 12 or the polishing composition obtained by the manufacturing method according to claim 13 or 14.

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