Polishing composition and polishing method

Abstract

To provide a polishing composition that can polish a resin polishing target at a high polishing speed to render its surface flat and smooth.SOLUTION: A polishing composition contains abrasive grains, a surfactant and water, and the surfactant contains an acetylene compound of the following chemical formula (1) having a carbon-carbon triple bond. R1, R2, R3, and R4 in the chemical formula (1) each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, and R5 and R6 each independently represent a substituted or unsubstituted alkylene group of 1 to 5 carbons, m is an integer of 1 or more, n is an integer of 0 or more, and m+n is 50 or less. This polishing composition is used for polishing a resin polishing target.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] A polishing composition used when polishing the surface of a resin object to be polished is required to have the ability to polish the object quickly (i.e., a high polishing rate) and the ability to polish the surface of the object to a flat, smooth surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 122191 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, Patent Document 1 discloses a polishing composition that satisfies the above requirements. However, there has been a demand for polishing compositions used to polish the surface of a resin object to be polished that have further improved capabilities for polishing the object quickly and polishing the surface of the object to a flat, smooth finish. An object of the present invention is to provide a polishing composition and a polishing method that are capable of polishing a resin object to be polished at a high polishing rate and polishing the surface of the resin object to be polished flat and smooth. [Means for solving the problem]

[0005] A polishing composition according to one embodiment of the present invention is a polishing composition used for polishing a resin object to be polished, and contains abrasive grains, a surfactant, and water. The surfactant contains an acetylene compound having a carbon-carbon triple bond and represented by the following chemical formula (1): R 1 , R 2 , R 3 , and R 4each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, R 5 and R 6 each independently represent a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms, m is an integer of 1 or more, n is an integer of 0 or more, and m+n is 50 or less.

[0006] [ka]

[0007] A polishing method according to another aspect of the present invention includes a polishing step of polishing a resin object to be polished using the polishing composition according to the above aspect. [Effects of the Invention]

[0008] According to the present invention, it is possible to polish a resin object at a high polishing rate, and also possible to polish the surface of the resin object to a flat, smooth surface. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will be described in detail. Note that the following embodiment shows an example of the present invention, and the present invention is not limited to this embodiment. Furthermore, various modifications and improvements can be made to the following embodiment, and such modifications and improvements can also be included in the present invention.

[0010] The polishing composition according to this embodiment is a polishing composition used for polishing a resin object, and contains abrasive grains, a surfactant, and water. The surfactant contains an acetylene compound having a carbon-carbon triple bond. The acetylene compound is a compound represented by the following chemical formula (1), and R in the following chemical formula (1) 1 , R 2 , R 3 , and R 4each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, R 5 and R 6 each independently represents a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms, m is an integer of 1 or more, n is an integer of 0 or more, and m+n is 50 or less.

[0011] [ka]

[0012] The polishing method according to this embodiment is a polishing method having a polishing step of polishing a resin object to be polished using the polishing composition according to this embodiment. The polishing composition according to this embodiment has an excellent ability to rapidly polish a resin object to be polished, and also has an excellent ability to polish the surface of the resin object to be polished flat and smooth. Therefore, when a resin object to be polished is polished using the polishing composition according to this embodiment, it is possible to polish the resin object to be polished at a high polishing rate, and also to polish the surface of the resin object to be polished flat and smooth. Therefore, it is possible to efficiently manufacture resin products with flat and smooth surfaces (for example, small surface roughness Ra, few defects such as scratches).

[0013] The polishing composition and polishing method according to this embodiment will be described in detail below. 1. About the object to be polished The type of object to be polished to which the polishing composition and polishing method according to the present embodiment are applied is not particularly limited as long as it is made of resin, and may be a member entirely formed of resin (resin member), or a member partially formed of resin. An example of a member partially formed of resin is a member in which a resin film is coated on the surface of a substrate.

[0014] The type of resin is not particularly limited, and examples thereof include thermoplastic resins and thermosetting resins. Examples of thermoplastic resins include fluororesins, acrylic resins (e.g., polymethyl acrylate, polymethyl methacrylate), polycarbonate, polyimide, polyamide, polyamideimide, polystyrene, polyvinyl chloride, polyethylene, polypropylene, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymers, polyvinyl alcohol, polyvinylidene chloride, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyphenyl ether, polysulfone, polyethersulfone, polyphenyl sulfide, polyarylate, polyetherimide, polyetheretherketone, liquid crystal polymers, ultra-high molecular weight polyethylene, and urethane resins.

[0015] Examples of fluororesins include fully fluorinated resins such as polytetrafluoroethylene (PTFE), partially fluorinated resins such as polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), and polyvinyl fluoride (PVF), and fluorinated resin copolymers such as perfluoroalkoxy fluororesin (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), and ethylene-chlorotrifluoroethylene copolymer (ECTFE).

[0016] Examples of thermosetting resins include phenolic resins, urea resins, melamine resins, unsaturated polyesters, epoxy resins, silicone resins, and polyurethanes. Among these resins, the polishing composition and polishing method according to this embodiment are particularly suitable for polishing fluororesin, acrylic resin, and polycarbonate.

[0017] 2. Surfactants The polishing composition according to this embodiment contains a surfactant, and this surfactant contains an acetylene compound represented by the above chemical formula (1). The action of the acetylene compound represented by chemical formula (1) hydrophilizes the resin surface, reducing the contact angle. As a result, the amount of adhesion of the polishing composition to the surface of the resin object to be polished and to the polishing pad is improved, making it possible to polish the object at a high polishing rate. In addition, the polishing composition adheres uniformly to the surface of the resin object to be polished, making it easier to polish the surface of the object to be polished uniformly, making it possible to polish the surface of the object to be polished flat and smooth.

[0018] It is believed that such effects are achieved because the acetylene compound is adsorbed to the abrasive grains, the resin object to be polished, and the polishing pad, thereby acting as a binder between the abrasive grains, the resin object to be polished, and the polishing pad. Note that the above mechanism for the effects is speculative. Furthermore, the present invention is not limited to the above mechanism.

[0019] Therefore, when polishing is performed using the polishing composition of this embodiment, even if the resin is highly water-repellent with a contact angle of 90° or more, the surface of the resin is hydrophilized by the action of the acetylene compound represented by chemical formula (1), and the contact angle becomes less than 90°. Therefore, it is possible to polish an object made of a highly water-repellent resin at a high polishing rate, and it is also possible to polish the surface of an object made of a highly water-repellent resin to a flat and smooth surface. Examples of highly water-repellent resins include the fluororesins mentioned above.

[0020] Of course, the polishing composition of this embodiment can also be applied to low-water-repellent resins with a contact angle of less than 90°, making it possible to polish objects made of low-water-repellent resins at a high polishing rate and to polish the surface of objects made of low-water-repellent resins to a flat, smooth surface.

[0021] The acetylene compound represented by chemical formula (1) preferably reduces the contact angle of the resin by 10° to 55°, more preferably by 10° to 45°. When the object to be polished is a highly water-repellent resin, the acetylene compound represented by chemical formula (1) more preferably reduces the contact angle of the resin by 20° to 45°.

[0022] Furthermore, the polishing composition of this embodiment can be applied to resins with low hardness and high elasticity, that is, resins that are soft and tough, and it is possible to polish objects made of resins with low hardness and high elasticity at a high polishing rate, and to polish the surface of objects made of resins with low hardness and high elasticity to a flat and smooth surface.

[0023] Here, low-hardness resin means a resin with a Rockwell hardness of HRM65 or less as specified in JIS K7202-2. The "HR" in "HRM" stands for Rockwell hardness, and "M" stands for hardness scale. High-elasticity resin means a resin with a tensile modulus of elasticity of 2.8 GPa or less. Specific examples of low-hardness, high-elasticity resins include polycarbonate (HRM56, tensile modulus of elasticity 2.1 GPa), epoxy resin (HRM45, tensile modulus of elasticity 2.2 GPa), and polytetrafluoroethylene (HRM19, tensile modulus of elasticity 0.6 GPa).

[0024] The HLB value of the acetylene compound represented by chemical formula (1) is preferably 4 or more and 19 or less, more preferably 7 or more and 18 or less, and even more preferably 10 or more and 18 or less. If the HLB value is within this range, a high polishing rate can be obtained, and the surface of the object to be polished after polishing becomes more flat and smooth. If the HLB value is 4 or more, the acetylene compound is easily dispersed in water, and if the HLB value is 10 or more, the acetylene compound is easily dissolved in water.

[0025] The HLB value of the acetylene compound represented by chemical formula (1) is particularly preferably from 10 to 15. When the HLB value is within this range, a high polishing rate can be obtained, the surface of the object to be polished after polishing becomes flatter and smoother, and foaming of the polishing composition can be suppressed, making the polishing composition easier to handle.

[0026] As can be seen from chemical formula (1), the acetylene compound represented by chemical formula (1) is an acetylene glycol-type compound having one acetylene group in one molecule and having an alkylene oxide added thereto. As the acetylene compound represented by chemical formula (1), a nonionic compound is more preferable from the viewpoint of polishing the surface of the object to be polished flatly and smoothly. The acetylene compound represented by chemical formula (1) may be used alone or in combination of two or more.

[0027] R in chemical formula (1) 1 , R 2 , R 3 , and R 4 are each independently a hydrogen atom or a substituted or unsubstituted alkyl group having from 1 to 20 carbon atoms, and the number of carbon atoms in the alkyl group may be 1 or more, 2 or more, 3 or more, or 20 or less, 18 or less, 16 or less, 15 or less, 12 or less, 10 or less, or 8 or less.

[0028] Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a hexyl group, an octyl group, a nonyl group, a decyl group, a lauryl group, a myristyl group, a palmityl group, and a stearyl group. 1 , R 2 , R 3 , and R 4 may all be the same, some may be the same and other may be different, or all may be different.

[0029] R in chemical formula (1) 5 and R 6 are each independently a substituted or unsubstituted alkylene group having from 1 to 5 carbon atoms, and the number of carbon atoms in the alkylene group may be 1 or more, 2 or more, 3 or more, or 4 or less, or 3 or less. Specific examples of the alkylene group include an ethylene group, a propylene group, a butylene group, and a pentylene group. R 5 and R 6 may be the same or different.

[0030] In chemical formula (1), m is an integer of 1 or more, n is an integer of 0 or more, and m+n is 50 or less, but m+n may be 1 or more, 3 or more, 5 or more, 10 or more, 15 or more, 20 or more, 50 or less, 30 or less, 22 or less, 16 or less, 12 or less, 8 or less, or 4 or less (for example, 3 or less). m and n may be the same or different.

[0031] The acetylene compound represented by chemical formula (1) has m R 5 , but m R 5 may all be the same type of alkylene group, or may have multiple types of alkylene groups. For example, R 5 may be ethylene and propylene groups, in which case R 5 The sum of the number of ethylene groups and the number of propylene groups is m.

[0032] R 6 The same is true for the acetylene compound represented by chemical formula (1). 6 but with n R 6 may all be the same type of alkylene group, or may have multiple types of alkylene groups. For example, R 6 may be ethylene and propylene groups, in which case R 6 The sum of the number of ethylene groups and the number of propylene groups is n.

[0033] It should be noted that, when producing the acetylene compound represented by chemical formula (1), it is difficult to completely control m and n. Therefore, when the acetylene compound represented by chemical formula (1) is produced, a mixture of multiple acetylene compounds with different values ​​of m+n is usually obtained. Therefore, the polishing composition according to this embodiment may contain multiple types of acetylene compounds represented by chemical formula (1). The polishing composition according to this embodiment may contain an acetylene compound in which m and n are both 0 in chemical formula (1).

[0034] Furthermore, the average value of the numerical value of m+n in chemical formula (1) (average number of moles added) may be 1 or more, 3 or more, 5 or more, 10 or more, 15 or more, or 20 or more, or may be 50 or less, 30 or less, 22 or less, 16 or less, 12 or less, 8 or less, or 4 or less (for example, 3 or less).

[0035] A particularly preferred example of the acetylene compound represented by chemical formula (1) is an acetylene compound represented by the following chemical formula (2). The acetylene compound represented by chemical formula (2) is 1 and R 4 is an isobutyl group, and R 2 and R 3 is a methyl group, and R 5 and R 6 is an ethylene group. p in chemical formula (2) is the same as m in chemical formula (1), and q in chemical formula (2) is the same as n in chemical formula (1).

[0036] [ka]

[0037] The molecular weight of the acetylene compound represented by chemical formula (1) is not particularly limited, but is preferably a molecular weight that fully exhibits its function in the polishing composition. The molecular weight of the acetylene compound represented by chemical formula (1) may be, for example, 250 or more, 300 or more, 400 or more, 500 or more, 700 or more, 1200 or more, or 1500 or more. The molecular weight of the acetylene compound represented by chemical formula (1) may be, for example, 3000 or less, 2000 or less, 1400 or less, 1000 or less, or 600 or less. The molecular weight of the acetylene compound represented by chemical formula (1) is calculated from the chemical formula.

[0038] The content of the acetylene compound represented by chemical formula (1) in the polishing composition of this embodiment is preferably 0.001 mass% or more, more preferably 0.005 mass% or more, and even more preferably 0.01 mass% or more, from the viewpoint of expressing the effect of adding the acetylene compound represented by chemical formula (1).

[0039] Furthermore, from the viewpoint of the cleaning properties of the acetylene compound represented by chemical formula (1), the content of the acetylene compound represented by chemical formula (1) in the polishing composition of this embodiment is preferably 0.2 mass% or less, more preferably 0.15 mass% or less, even more preferably 0.1 mass% or less, and particularly preferably 0.09 mass% or less.

[0040] Therefore, the content of the acetylene compound represented by chemical formula (1) in the polishing composition of this embodiment is preferably 0.001 mass% or more and 0.2 mass% or less, more preferably 0.005 mass% or more and 0.15 mass% or less, even more preferably 0.01 mass% or more and 0.1 mass% or less, and particularly preferably 0.01 mass% or more and 0.09 mass% or less. The above content of the acetylene compound represented by chemical formula (1) in the polishing composition according to this embodiment can be preferably applied to the content in the polishing liquid (working slurry) supplied to the object to be polished, for example.

[0041] The surfactant contained in the polishing composition according to this embodiment may consist solely of the acetylene compound represented by chemical formula (1), or may consist of the acetylene compound represented by chemical formula (1) and other surfactants. The other surfactants may be any of anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants.

[0042] Specific examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, polyoxyethylene alkyl sulfate, alkyl sulfate, polyoxyethylene alkyl sulfate, alkyl sulfate, alkylbenzene sulfonate, alkyl phosphate, polyoxyethylene alkyl phosphate, polyoxyethylene sulfosuccinate, alkyl sulfosuccinate, alkyl naphthalene sulfonate, alkyl diphenyl ether disulfonate, or salts thereof.

[0043] Specific examples of cationic surfactants include alkyltrimethylammonium salts, alkyldimethylammonium salts, alkylbenzyldimethylammonium salts, and alkylamine salts. Further, specific examples of amphoteric surfactants include alkylbetaines and alkylamine oxides.

[0044] Further, specific examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyalkylene alkyl ethers, sorbitan fatty acid esters, glycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkylamines, and alkylalkanolamides.

[0045] 3. About abrasive grains The type of abrasive grains contained in the polishing composition according to this embodiment is not particularly limited, but for example, particles made of metal oxides such as alumina (Al2O3), silica (SiO2), cerium oxide (CeO2), zirconia (ZrO2), titania (TiO2), iron oxide (FeO, Fe3O4, Fe2O3), manganese oxide (MnO, Mn3O4, Mn2O3, MnO2) can be used. Among these abrasive grains, alumina and silica are preferred, and alumina is more preferred.

[0046] The type of alumina is not particularly limited, and examples include α-alumina, δ-alumina, θ-alumina, κ-alumina, and amorphous alumina. When α-alumina is used, the α-alumina ratio is not particularly limited, but is preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more. When α-alumina is used, the α-alumina ratio is 100% or less, preferably 99% or less, and more preferably 97% or less. Within this range, a high polishing rate can be obtained while maintaining a good surface shape. The α-alumina ratio can be determined, for example, from the integrated intensity ratio of the (113) plane diffraction line by X-ray diffraction measurement. The type of silica is not particularly limited, but examples thereof include colloidal silica, fumed silica, sol-gel silica, and precipitated silica. These abrasive grains may be used alone or in combination of two or more kinds.

[0047] The particle size of the abrasive grains contained in the polishing composition according to this embodiment is not particularly limited, but is preferably as follows. The 50% particle size in the cumulative particle size distribution on a volume basis of the abrasive grains (the secondary particle size at which the cumulative frequency from the small particle size side is 50%, hereinafter sometimes referred to as "D50") is not particularly limited, but from the viewpoint of polishing speed, when the abrasive grains are alumina, D50 is preferably 0.1 μm or more, more preferably 0.15 μm or more, and even more preferably 0.2 μm or more. When the abrasive grains are silica, D50 is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 0.15 μm or more.

[0048] Furthermore, from the viewpoint of the surface quality of the polished object after polishing (i.e., surface flatness and smoothness), when the abrasive grains are alumina, the D50 of the abrasive grains is preferably 5 μm or less, may be 4 μm or less, may be 3 μm or less, may be 1.5 μm or less, more preferably 1 μm or less, even more preferably 0.5 μm or less, and particularly preferably 0.3 μm or less. When the abrasive grains are silica, the D50 is preferably 1 μm or less, may be 0.5 μm or less, more preferably 0.3 μm or less, even more preferably 0.25 μm or less, and particularly preferably 0.2 μm or less. In the present invention, the volume-based cumulative particle size distribution is measured using a laser diffraction / scattering particle size distribution analyzer.

[0049] The 10% particle size (the secondary particle size where the cumulative frequency from the small particle side is 10%; hereinafter, sometimes referred to as "D10") in the volume-based cumulative particle size distribution of the abrasive grains is not particularly limited, but when the abrasive grains are alumina, it is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 0.15 μm or more. When the abrasive grains are alumina, D10 is preferably 1 μm or less, more preferably 0.7 μm or less, even more preferably 0.5 μm or less, even more preferably 0.3 μm or less, particularly preferably 0.25 μm or less, and most preferably 0.2 μm or less. If the D10 of the abrasive grains is within this range, the surface of the object to be polished will be flatter and smoother after polishing.

[0050] The 90% particle size (the secondary particle size where the cumulative frequency from the small particle side is 90%, hereinafter sometimes referred to as "D90") in the cumulative particle size distribution on a volume basis of the abrasive grains is not particularly limited, but when the abrasive grains are alumina, it is preferably 0.15 μm or more, more preferably 0.2 μm or more, even more preferably 0.25 μm or more, and particularly preferably 0.3 μm or more. If the D90 of the abrasive grains is within this range, a high polishing rate can be obtained.

[0051] Furthermore, when the abrasive grains are alumina, D90 is preferably 8 μm or less, more preferably 3 μm or less, even more preferably 2 μm or less, even more preferably 1 μm or less, even more preferably 0.6 μm or less, particularly preferably 0.5 μm or less, and most preferably 0.4 μm or less. If the D90 of the abrasive grains is within this range, the surface of the object to be polished after polishing will be more flat and smooth.

[0052] When the abrasive grains are made of alumina, the ratio of D90 to D50 (D90 / D50) is preferably 1.1 or more, more preferably 1.2 or more. If D90 / D50 is within this range, a high polishing rate can be obtained. Furthermore, when the abrasive grains are made of alumina, D90 / D50 is preferably 2.5 or less, more preferably 1.7 or less, and even more preferably 1.5 or less. If D90 / D50 is within this range, the surface of the object to be polished after polishing will be more flat and smooth.

[0053] When the abrasive grains are made of alumina, the ratio of D90 to D10 (D90 / D10) is preferably 1.2 or more, more preferably 1.3 or more, even more preferably 1.5 or more, and particularly preferably 1.7 or more. A high polishing rate can be achieved when D90 / D10 is within this range. Furthermore, when the abrasive grains are made of alumina, D90 / D10 is preferably 6.5 or less, more preferably 3.0 or less, even more preferably 2.5 or less, and particularly preferably 2.1 or less. When D90 / D10 is within this range, the surface of the object to be polished after polishing becomes flatter and smoother.

[0054] When the abrasive grains are made of alumina, the ratio of D50 to D10 (D50 / D10) is preferably 1.1 or more, more preferably 1.2 or more. If D50 / D10 is within this range, a high polishing rate can be obtained. Furthermore, when the abrasive grains are made of alumina, D50 / D10 is preferably 2.0 or less, more preferably 1.8 or less, and even more preferably 1.6 or less. If D50 / D10 is within this range, the surface of the object to be polished after polishing will be more flat and smooth.

[0055] The BET specific surface area of ​​the abrasive grains is not particularly limited, but when the abrasive grains are alumina, the BET specific surface area is 5 m 2 / g or more, and 2 / g or more is more preferable, and 15m 2It is more preferable that the BET specific surface area of ​​the abrasive grains is 250 m / g or more. 2 / g or less, and 2 / g or less is more preferable, and 50m 2 / g or less is more preferable, and 25m 2 If the BET specific surface area of ​​the abrasive grains is within this range, a high polishing rate can be obtained and the surface of the object to be polished after polishing will be flatter and smoother. The BET specific surface area of ​​the abrasive grains can be measured using, for example, a Micromeritics FlowSorb II 2300. The gas that can be adsorbed onto the abrasive grains may be nitrogen gas (N), argon (Ar), krypton (Kr), or the like.

[0056] In addition, the content of abrasive grains in the polishing composition of this embodiment is not particularly limited, but when the abrasive grains are alumina, it is preferably 0.1 mass% or more, more preferably 1 mass% or more, and even more preferably 3 mass% or more.In addition, when the abrasive grains are silica, it is preferably 0.1 mass% or more, more preferably 1 mass% or more, and even more preferably 3 mass% or more.If the content of abrasive grains is within this range, it can obtain high polishing speed.

[0057] Furthermore, when the abrasive grains in the polishing composition according to this embodiment are alumina, the content of the abrasive grains is preferably 40% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less. When the abrasive grains are silica, the content is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less. When the abrasive grain content is within this range, scratches on the polished object can be reduced after polishing. Furthermore, the cost of the polishing composition can be reduced.

[0058] 4. pH of the polishing composition The pH of the polishing composition of this embodiment is not particularly limited, but is preferably 13 or less, more preferably 12 or less. The pH of the polishing composition of this embodiment is preferably 2 or more, more preferably 3 or more. If the pH is within the above range, a high removal rate can be obtained. Furthermore, a polishing composition having a pH within the above range is relatively safe and can be handled more safely.

[0059] The pH of the polishing composition according to this embodiment is preferably 7 or less, and more preferably less than 7 (that is, more preferably acidic). When the abrasive grains are alumina, if the pH of the polishing composition is less than 7, the abrasive grains will have a positive zeta potential, which makes it easier for the abrasive grains to adhere to the surface of the object to be polished, which has a negative zeta potential, thereby improving the polishing rate. In addition, since the abrasive grains have a positive zeta potential, the abrasive grains will repel each other and will not easily aggregate, improving the dispersibility of the abrasive grains. The pH of the polishing composition according to this embodiment may be adjusted by using a pH adjuster, which is an additive, as will be described in detail later.

[0060] 5. About water The polishing composition according to this embodiment is a slurry containing abrasive grains, a surfactant, and water. The water functions as a dispersion medium or solvent for dispersing or dissolving each component of the polishing composition (abrasive grains, surfactant, additives, etc.). One or more organic solvents may be mixed with the water. From the viewpoint of preventing the inhibition of the action of each component constituting the polishing composition according to this embodiment, it is preferable to use water containing as few impurities as possible. Specifically, it is preferable to use pure water or ultrapure water obtained by removing impurity ions with an ion exchange resin and then passing it through a filter to remove foreign matter, or distilled water.

[0061] The water content in the polishing composition is not particularly limited, but may be 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more (for example, 70% by mass or more). When a mixed solvent of water and a solvent other than water is used as the dispersion medium or solvent, the ratio of water to the solvent other than water may be 100:0 to 50:50 or 99:1 to 60:40.

[0062] 6. Additives The polishing composition according to the present embodiment may further contain additives other than surfactants as necessary to improve its performance.As additives, known additives contained in general polishing compositions can be used.For example, various additives such as pH adjusters, oxidizing agents, polishing accelerators, water-soluble polymers, chelating agents, dispersing aids, antiseptics, and antifungal agents may be added.

[0063] 6-1 pH adjusters To the polishing composition of this embodiment, a pH adjuster may be added as needed to adjust the pH to a desired value. One pH adjuster may be used alone, or two or more pH adjusters may be used in combination. Known acids, bases, or salts thereof may be used as the pH adjuster.

[0064] Specific examples of acids that can be used as pH adjusters include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, and phosphoric acid, and organic acids such as 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, and phenoxyacetic acid.

[0065] When an inorganic acid is used as the pH adjuster, sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, etc. are preferred from the viewpoint of improving the polishing rate, and when an organic acid is used as the pH adjuster, glycolic acid, succinic acid, maleic acid, citric acid, tartaric acid, malic acid, gluconic acid, itaconic acid, etc. are preferred.

[0066] Examples of bases that can be used as pH adjusters include amines such as aliphatic amines and aromatic amines, organic bases such as quaternary ammonium hydroxide, alkali metal hydroxides such as potassium hydroxide, alkaline earth metal hydroxides, ammonia, etc. Among these bases, potassium hydroxide and ammonia are preferred because of their availability.

[0067] Alternatively, instead of or in combination with the above acids, salts of the above acids, such as ammonium salts or alkali metal salts, may be used as pH adjusters. In particular, salts of a weak acid and a strong base, a strong acid and a weak base, or a weak acid and a weak base can be expected to have a pH buffering effect, and in the case of a salt of a strong acid and a strong base, a small amount can be used to adjust not only the pH but also the electrical conductivity. The amount of the pH adjuster to be added is not particularly limited, and may be adjusted appropriately so that the polishing composition has a desired pH.

[0068] 6-2 Oxidizing agents If necessary, an oxidizing agent may be added to the polishing composition according to this embodiment in order to oxidize the surface of the object to be polished. The oxidizing agent has the effect of oxidizing the surface of the object to be polished, and when an oxidizing agent is added to the polishing composition, the polishing rate of the polishing composition is improved. Usable oxidizing agents include, for example, peroxides, nitric acid, and potassium permanganate. Specific examples of peroxides include hydrogen peroxide, peracetic acid, percarbonates, urea peroxide, perchlorates, and persulfates (e.g., sodium persulfate, potassium persulfate, and ammonium persulfate).

[0069] 6-3 Polishing accelerators A polishing accelerator may be added to the polishing composition. The polishing accelerator plays a role in chemically polishing the object to be polished, and by acting on the surface of the object to be polished, it can significantly improve processing efficiency. The polishing accelerator may be used alone or in combination of two or more. Among the polishing accelerators, aluminum salts of monovalent acids are preferred, as they function as polishing accelerators and improve the surface quality of the polished surface of the object to be polished. Preferred examples of aluminum salts of monovalent acids include aluminum nitrate (Al(NO3)3) and aluminum chloride (AlCl3).

[0070] From the viewpoint of more reliably improving the polishing ability of the polishing composition, the content of aluminum salt of a monovalent acid in the polishing composition is preferably 0.01 mass% or more, more preferably 2 mass% or more, even more preferably 4 mass% or more, particularly preferably more than 4 mass%, and most preferably 5 mass% or more.

[0071] On the other hand, since a large amount of the aluminum salt of a monovalent acid does not significantly improve performance and is disadvantageous in terms of cost, the content of the aluminum salt of a monovalent acid in the polishing composition is preferably 15 mass% or less. When the aluminum salt of a monovalent acid has water of hydration, these contents exclude the water of hydration.

[0072] The polishing composition according to this embodiment may contain a polishing accelerator other than aluminum nitrate or aluminum chloride. Examples of the polishing accelerator other than aluminum nitrate or aluminum chloride include inorganic acids, organic acids, and salts of these acids. Specific examples of inorganic acids include phosphoric acid, nitric acid, sulfuric acid, hydrochloric acid, hypophosphorous acid, phosphonic acid, boric acid, and sulfamic acid.

[0073] Specific examples of organic acids include citric acid, maleic acid, malic acid, glycolic acid, succinic acid, itaconic acid, malonic acid, iminodiacetic acid, gluconic acid, lactic acid, mandelic acid, tartaric acid, crotonic acid, nicotinic acid, acetic acid, adipic acid, formic acid, oxalic acid, propionic acid, valeric acid, caproic acid, caprylic acid, capric acid, cyclohexanecarboxylic acid, phenylacetic acid, benzoic acid, crotonic acid, methacrylic acid, glutaric acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, glycolic acid, and tartaric acid. Ronic acid, glyceric acid, hydroxybutyric acid, hydroxyacetic acid, hydroxybenzoic acid, salicylic acid, isocitric acid, methylenesuccinic acid, gallic acid, ascorbic acid, nitroacetic acid, oxaloacetic acid, glycine, alanine, glutamic acid, aspartic acid, valine, leucine, isoleucine, serine, threonine, cysteine, methionine, phenylalanine, tryptophan, tyrosine, proline, cystine, glutamine, asparagine, lysine, arginine, nicotinic acid, picolinic acid , methyl acid phosphate, ethyl acid phosphate, ethyl glycol acid phosphate, isopropyl acid phosphate, phytic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri(methylenephosphonic acid), ethylenediaminetetra(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid phosphonic acid, ethanehydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid, α-methylphosphonosuccinic acid, aminopoly(methylene phosphonic acid), methanesulfonic acid, ethanesulfonic acid, aminoethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 2-naphthalenesulfonic acid, and the like.

[0074] Examples of salts of these acids include metal salts (e.g., alkali metal salts such as lithium salts, sodium salts, and potassium salts), ammonium salts (e.g., quaternary ammonium salts such as tetramethylammonium salts and tetraethylammonium salts), and alkanolamine salts (e.g., monoethanolamine salts, diethanolamine salts, and triethanolamine salts) of the above-mentioned inorganic acids and organic acids.

[0075] Specific examples of salts include alkali metal phosphates and alkali metal hydrogen phosphates such as tripotassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, trisodium phosphate, disodium hydrogen phosphate, and sodium dihydrogen phosphate. Specific examples of salts include alkali metal salts of the organic acids exemplified above, as well as alkali metal salts of glutamic acid diacetic acid, alkali metal salts of diethylenetriaminepentaacetic acid, alkali metal salts of hydroxyethylethylenediaminetriacetic acid, and alkali metal salts of triethylenetetraminehexaacetic acid. The alkali metal in these alkali metal salts is, for example, lithium, sodium, or potassium.

[0076] 6-4 Water-soluble polymers A water-soluble polymer may be added to the polishing composition according to this embodiment. The type of water-soluble polymer is not particularly limited, and examples thereof include glycols such as polyalkylene oxide alkyl ethers, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, and polypropylene glycol, as well as pyrrolidone compounds having a 2-pyrrolidone group (e.g., poly-N-vinylpyrrolidone), and caprolactam compounds. Other examples of water-soluble polymers include cellulose derivatives, starch derivatives, polyacrylic acid (or its salts), polyacrylamide, polyvinyl alcohol, polyethyleneimine, and polyalkylene oxides. Among these water-soluble polymers, pyrrolidone compounds having a 2-pyrrolidone group and caprolactam compounds are more preferred.

[0077] The weight-average molecular weight of the water-soluble polymer is preferably 3,000 or more, more preferably 5,000 or more, even more preferably 10,000 or more, and particularly preferably 30,000 or more. Water-soluble polymers having such weight-average molecular weights have the technical effect of improving the dispersibility of the slurry. Furthermore, the weight-average molecular weight of the water-soluble polymer is preferably 500,000 or less, more preferably 300,000 or less, and even more preferably 100,000 or less. Water-soluble polymers having such weight-average molecular weights have the technical effect of improving stability.

[0078] The pyrrolidone compound having a 2-pyrrolidone group, when contained in the polishing composition together with the aluminum salt of a monovalent acid, effectively promotes the polishing of resin.The type of pyrrolidone compound having a 2-pyrrolidone group is not particularly limited, but for example, N-octyl-2-pyrrolidone, N-dodecyl-2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, N-butyl-2-pyrrolidone, N-hexyl-2-pyrrolidone, N-decyl-2-pyrrolidone, N-octadecyl-2-pyrrolidone, N-hexadecyl-2-pyrrolidone, poly-N-vinylpyrrolidone, and poly-N-vinylpyrrolidone copolymers can be mentioned.These pyrrolidone compounds having a 2-pyrrolidone group can be used alone or in combination of two or more.

[0079] The pyrrolidone compound having a 2-pyrrolidone group is preferably poly-N-vinylpyrrolidone (hereinafter sometimes referred to as "PVP"). The weight-average molecular weight of PVP is preferably 3,000 or more, more preferably 10,000 or more. The weight-average molecular weight of PVP is preferably 60,000 or less, more preferably 50,000 or less. PVP having a weight-average molecular weight within these ranges is readily available from various chemical product suppliers.

[0080] The content of the pyrrolidone compound in the polishing composition according to this embodiment is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more. The content of the pyrrolidone compound in the polishing composition according to this embodiment is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less.

[0081] Caprolactam compound is a nitrogen-containing organic compound called ε-caprolactam, and can be used as a substitute for the above-mentioned pyrrolidone compound.The content of caprolactam compound in the polishing composition according to this embodiment is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, and even more preferably 0.1 mass% or more.In addition, the content of caprolactam compound in the polishing composition according to this embodiment is preferably 5 mass% or less, more preferably 2 mass% or less, and even more preferably 1 mass% or less.

[0082] 6-5 Chelating agents The polishing composition according to this embodiment may contain a chelating agent, if necessary, to capture metal impurities in the polishing system to form a complex, thereby suppressing metal contamination of the object to be polished. Specific examples of the chelating agent include carboxylic acids, amines, organic phosphonic acids, and amino acids. 6-6 Dispersing agents To facilitate redispersion of abrasive grain aggregates, a dispersing agent may be added to the polishing composition according to this embodiment, as needed. Specific examples of the dispersing agent include condensed phosphates such as pyrophosphates and hexametaphosphates.

[0083] 6-7 Preservatives and anti-mold agents The polishing composition according to this embodiment may contain, if necessary, an antiseptic or an antifungal agent, such as an isothiazolin-based antiseptic such as 2-methyl-4-isothiazolin-3-one or 5-chloro-2-methyl-4-isothiazolin-3-one, a parahydroxybenzoic acid ester, or phenoxyethanol.

[0084] 7. Manufacturing method of polishing composition The method for producing the polishing composition of this embodiment is not particularly limited, and can be produced by stirring and mixing abrasive grains, the above-mentioned acetylene compound, and if desired, various additives in water.The temperature when mixing each component is not particularly limited, but is preferably 10 ℃ or more and 40 ℃ or less, and can be heated to improve dissolution rate.In addition, the mixing time is also not particularly limited.

[0085] The polishing composition according to this embodiment may be a single-component type, or a multi-component type (two or more components) in which some or all of the components of the polishing composition are mixed in any ratio. The polishing composition according to this embodiment may also be prepared by diluting the stock solution of the polishing composition with water, for example, 10 times or more. When the polishing composition is a two-component type, the order of mixing and diluting the two raw material compositions that serve as the raw materials for the polishing composition is arbitrary. For example, one raw material composition may be diluted with water and then mixed with the other raw material composition, or both raw material compositions may be mixed and diluted with water simultaneously, or both raw material compositions may be mixed and then diluted with water.

[0086] 8. Polishing equipment and polishing methods The method and conditions for polishing a resin object to be polished using the polishing composition according to this embodiment are not particularly limited, and polishing can be performed by appropriately selecting a method and conditions suitable for polishing the object to be polished within the range of general polishing methods and conditions. In addition, general single-sided polishing machines or double-sided polishing machines can be used as the polishing machine. When polishing using a single-sided polishing device, the object to be polished is held using a holder called a carrier, a polishing composition is interposed between the object to be polished and the polishing pad, a platen with a polishing pad attached is pressed against one side of the object to be polished, and the platen is rotated to polish one side of the object to be polished.

[0087] When polishing using a double-sided polishing machine, the object to be polished is held using a carrier, a polishing composition is interposed between the object to be polished and the polishing pad, a platen to which a polishing pad is attached is pressed against both sides of the object to be polished, and the polishing pad and the object to be polished are rotated in opposite directions to polish both sides of the object to be polished. Regardless of which polishing device is used, the object to be polished is polished by the physical action of friction between the polishing pad and polishing composition and the object to be polished, and by the chemical action of the polishing composition on the object to be polished.

[0088] The type of polishing pad is not particularly limited, and pads with various physical properties such as material, thickness, hardness, etc. can be used. Examples of polishing pad materials include polyurethane, epoxy resin, nonwoven fabric, suede, etc. The polishing pad may also have grooves formed therein to allow the polishing composition to accumulate.

[0089] [Example] The present invention will be described in more detail below with reference to examples and comparative examples. Example 1 After mixing the abrasive grains, nonionic surfactant, and water, the pH was adjusted to 3.2 by adding a pH adjuster (nitric acid or potassium hydroxide aqueous solution) to produce the polishing composition of Example 1. Alumina with a D50 of 0.7 μm was used as the abrasive grains. The content of the abrasive grains in the polishing composition was 15 mass %. An acetylene compound represented by chemical formula (2) was used as the surfactant. This acetylene compound has an HLB value of 8. The HLB value can be adjusted by the values ​​of p and q in chemical formula (2). The content of the surfactant in the polishing composition was 0.05 mass %.

[0090] Next, the surface of a resin object to be polished was polished using the polishing composition. The object to be polished was a plate-shaped member made of polytetrafluoroethylene (PTFE). The polishing conditions were as follows: Polishing device: Engis single-sided polishing device EJ-380IN (surface plate diameter 380mm) Polishing pad: Suede polishing pad (N17(HD)NX_202U manufactured by Fujibo Ehime Co., Ltd.) Polishing load: 9.8kPa (100gf / cm 2 ) Rotation speed of the surface plate: 80 min -1 Polishing speed (linear speed): 95.5m / min Polishing time: 5 min Polishing composition supply rate: 15 mL / min

[0091] After polishing, the surface roughness Ra and static contact angle of the polished surface of the object were measured. The surface roughness Ra of the polished surface of the object after polishing was measured using a Keyence Corporation Laser Microscope VK-X200 measuring device with a field of view of 284 × 213 μm. The static contact angle of the polished surface of the object after polishing was also measured using a Matsubo Corporation portable contact angle meter PG-X+ (water drop volume: 40 μL). Furthermore, the thickness of the object before and after polishing was measured, and the polishing rate was calculated by dividing the difference in thickness by the polishing time. The results are shown in Table 1.

[0092] [Table 1]

[0093] (Examples 2 and 3) A polishing composition was prepared in the same manner as in Example 1, except that the type of nonionic surfactant used was different, and polishing of an object to be polished was carried out in the same manner as in Example 1. The surfactant used was an acetylene compound represented by chemical formula (2), but the values ​​of p and q in chemical formula (2) were different from those used in Example 1. Therefore, the HLB value was different. The results are shown in Table 1.

[0094] (Comparative Example 1) Except for not using a surfactant, a polishing composition was prepared in the same manner as in Example 1, and polishing of an object to be polished was carried out in the same manner as in Example 1. The results are shown in Table 1. (Comparative Example 2-4) A polishing composition was prepared in the same manner as in Example 1, except that the type of nonionic surfactant used was different, and polishing of an object to be polished was carried out in the same manner as in Example 1. The surfactant used in Comparative Example 2 was polyoxyethylene alkyl ether, and in Comparative Examples 3 and 4, it was polyoxyalkylene alkyl ether. The HLB values ​​of the surfactants differ between Comparative Example 3 and Comparative Example 4. The results are shown in Table 1.

[0095] Example 4 The polishing composition of Example 4 was prepared by mixing abrasive grains, a nonionic surfactant, aluminum nitrate nonahydrate (Al(NO3)3 9H2O), PVP, and water, and then adjusting the pH to 3.2 by adding a pH adjuster (nitric acid or potassium hydroxide aqueous solution). The same alumina as in Example 1 was used as the abrasive grains. The content of the abrasive grains in the polishing composition was 15% by mass. The same acetylene compound as in Example 1 was used as the surfactant. The content of the surfactant in the polishing composition was 0.05% by mass. The content of aluminum nitrate nonahydrate in the polishing composition was 10% by mass. The content of PVP in the polishing composition was 0.05% by mass.

[0096] Next, the polishing composition of Example 4 was used to polish the surface of a resin object to be polished. The object to be polished was a plate-shaped member made of polytetrafluoroethylene. The polishing conditions were the same as in Example 1. After polishing was completed, the surface roughness Ra and static contact angle of the polished surface of the polished object were measured, and the polishing rate was calculated, in the same manner as in Example 1. The results are shown in Table 1.

[0097] Example 5 A polishing composition was prepared in the same manner as in Example 4, except that the type of nonionic surfactant used was different, and polishing of an object to be polished was carried out in the same manner as in Example 4. The surfactant used was the same acetylene compound as in Example 3. The results are shown in Table 1. (Comparative Example 5) A polishing composition was prepared in the same manner as in Example 4 except that no surfactant was used, and polishing of an object to be polished was carried out in the same manner as in Example 4. The results are shown in Table 1. (Comparative Examples 6 and 7) A polishing composition was prepared in the same manner as in Example 4, except that the type of nonionic surfactant used was different, and polishing of an object to be polished was carried out in the same manner as in Example 4. The surfactant used in Comparative Example 6 was the same as in Comparative Example 2, and the surfactant used in Comparative Example 7 was the same as in Comparative Example 4. The results are shown in Table 1.

[0098] Example 6 A polishing composition was prepared in the same manner as in Example 4, and an object to be polished was polished in the same manner as in Example 4, except that the object to be polished was a plate-shaped member made of polymethyl methacrylate (PMMA). The results are shown in Table 1. (Comparative Example 8) A polishing composition was prepared in the same manner as in Comparative Example 5, and an object to be polished was polished in the same manner as in Example 4, except that the object to be polished was a plate-like member made of PMMA. The results are shown in Table 1. (Comparative Example 9) A polishing composition was prepared in the same manner as in Comparative Example 6, and an object to be polished was polished in the same manner as in Example 4, except that the object to be polished was a plate-like member made of PMMA. The results are shown in Table 1.

[0099] Example 7 A polishing composition was prepared in the same manner as in Example 4, and an object to be polished was polished in the same manner as in Example 4, except that the object to be polished was a plate-shaped member made of polycarbonate (PC). The results are shown in Table 1. (Comparative Example 10) A polishing composition was prepared in the same manner as in Comparative Example 5, and an object to be polished was polished in the same manner as in Example 4, except that the object to be polished was a plate-shaped member made of PC. The results are shown in Table 1. (Comparative Example 11) A polishing composition was prepared in the same manner as in Comparative Example 6, and an object to be polished was polished in the same manner as in Example 4, except that the object to be polished was a plate-shaped member made of PC. The results are shown in Table 1. (Examples 8 and 9) A polishing composition was prepared in the same manner as in Example 4 except that the content of the surfactant was different, and polishing of an object to be polished was carried out in the same manner as in Example 4. The results are shown in Table 1.

[0100] As can be seen from the results shown in Table 1, Examples 1-9 had a high polishing rate. In addition, the surface roughness Ra of the polished surface of the object to be polished after polishing was small, and the surface of the resin object to be polished could be polished flat and smooth. In contrast, in Comparative Example 1-11, the polishing rate was lower and the surface roughness Ra of the polished surface was smaller than in the corresponding Examples.

Claims

1. A polishing composition used for polishing a resin object to be polished contains abrasive grains, a surfactant, and water, and further contains an aluminum salt of a monovalent acid, and a pyrrolidone compound or a caprolactam compound having a 2-pyrrolidone group, wherein the surfactant contains an acetylene compound having a carbon-carbon triple bond and represented by the following chemical formula (1): R 1 and R 4 in the following chemical formula (1) are isobutyl groups, R 2 and R 3 are methyl groups, and R 5 and R 6 is an ethylene group, m is an integer of 1 or more, n is an integer of 0 or more, and m+n is 1 or more and 8 or less. 【Chemistry 1】

2. 2. The polishing composition according to claim 1, wherein the abrasive grains are at least one of alumina and silica.

3. 2. The polishing composition according to claim 1, wherein the abrasive grains are alumina.

4. 4. The polishing composition according to claim 1, wherein the acetylene compound has an HLB value of 10 or more and 18 or less.

5. 5. The polishing composition according to claim 1, having a pH of 7 or less.

6. 6. The polishing composition according to claim 1, wherein the resin is a highly water-repellent resin having a contact angle of 90° or more.

7. 6. The polishing composition according to claim 1, wherein the resin is a low-hardness, high-elasticity resin having a Rockwell hardness of HRM 65 or less and a tensile modulus of elasticity of 2.8 GPa or less.

8. A polishing method having a polishing step of polishing a resin object to be polished using the polishing composition according to any one of claims 1 to 7.

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