Dispersant for fluorinated resin particles

Abstract

To provide a non-fluorinated dispersant capable of achieving dispersibility equivalent to that of a fluorinated dispersant in a dispersion containing dispersed fluorinated resin particles.SOLUTION: There is provided a dispersant for fluorinated resin particles for dispersing fluorinated resin particles in a liquid, the dispersant comprising: (1) a non-fluorinated copolymer containing, as repeating units, (a) a Si-O-bond-containing monomer having one polymerizable functional group in a single molecule, the polymerizable functional group being a (meth)acryloyl group, and (b) a (meth)acryloyl-group-containing monomer having one polymerizable functional group in a single molecule, the polymerizable functional group being a (meth)acryloyl group, except that the Si-O-bond-containing monomer is excluded; and (2) an organic solvent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a novel dispersant for fluorine-containing resin particles. [Background technology]

[0002] Fluorine-based resins such as polytetrafluoroethylene (PTFE) have excellent heat resistance, chemical resistance, lubricity, etc., and are therefore used as surface coating layers (cured films) for various products, such as everyday items such as cooking utensils, containers, and office equipment, mechanical parts such as valves and bearings, and electronic equipment manufacturing equipment such as chemical vats and tanks. These surface coating layers are generally formed by using a dispersion obtained by dispersing fluorine-based resin particles in an organic solvent as a coating liquid, applying this to the surface of the article, and drying it.

[0003] In the dispersion liquids described above, fluorine-based dispersants have conventionally been used frequently as dispersants for dispersing fluorine-based resin particles in organic solvents (for example, Patent Documents 1 and 2).

[0004] However, in recent years, in light of environmental issues caused by so-called PFAS (a group of compounds consisting of perfluoroalkyl compounds and polyfluoroalkyl compounds), development of non-fluorinated dispersants has been progressing.

[0005] For example, polyoxyalkylene-modified polydimethylsiloxanes have been proposed that have a weight-average molecular weight of 3000 or less and an HLB value calculated by the Griffin equation of 1 to 18 (Patent Document 3).

[0006] Furthermore, for example, a method has been proposed in which a nonionic silicone surfactant is used as a dispersant (Patent Document 4).

[0007] Additionally, a method is known in which a water-soluble polymer containing polydopamine and an amino group is used to enhance the dispersibility of fluorine-based resin particles (Patent Document 5). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 3986579 [Patent Document 2] Patent No. 5247643 [Patent Document 3] International Publication WO2022 / 50253 [Patent Document 4] International Publication WO2021 / 75504 [Patent Document 5] Patent Publication No. 2022-164144 Summary of the Invention [Problem to be solved by the invention]

[0009] However, although conventional silicone surfactants can provide a certain degree of dispersibility, they have lower performance than existing fluorine-based dispersants, and are therefore inadequate as a substitute for fluorine-based dispersants.

[0010] On the other hand, as concerns about the effects of PFAS on humans and plants and animals are growing, for example, environmental issues caused by PFAS in rivers and other areas in Japan have recently been widely reported, the development of fluorine-free dispersants is considered an urgent need.

[0011] Therefore, an object of the present invention is to provide a non-fluorine-based dispersant that can provide excellent dispersibility equivalent to that of a fluorine-based dispersant in a dispersion of fluorine-based resin particles. [Means for solving the problem]

[0012] The present inventors have conducted extensive research in light of the problems of the prior art and have found that the above-mentioned object can be achieved by a composition containing a specific non-fluorinated copolymer component, thereby completing the present invention.

[0013] That is, the present invention relates to the following dispersant for fluorine-based resin particles. 1. A dispersant for dispersing fluororesin particles in a liquid, (1) A non-fluorine-containing copolymer containing, as repeating units, (a) an Si-O bond-containing monomer having one polymerizable functional group in one molecule, the polymerizable functional group being a (meth)acryloyl group, and (b) a (meth)acryloyl group-containing monomer having one polymerizable functional group in one molecule, the polymerizable functional group being a (meth)acryloyl group (excluding the Si-O bond-containing monomer), and (2) Organic solvents A dispersant for fluorine-based resin particles, comprising: 2. The Si—O bond-containing monomer is represented by the following general formula (1): [ka] (where m represents 1 to 5. R 1 represents an acryloyl group or a methacryloyl group. 21 and R 22 are the same or different and represent a trialkylsiloxy group or an alkyl group having 1 to 3 carbon atoms. 3 is a trialkylsiloxy group or a siloxane group of the following general formula (2): [ka] (where n is a number between 0 and 30. 4 ~R 8 are the same or different and represent an alkyl group having 1 to 4 carbon atoms. is a monomer represented by Item 1. The dispersant for fluorine-based resin particles according to item 1. 3. The (meth)acryloyl group-containing monomer is represented by the following general formula (3): [ka] (where y represents 1 to 100. R 9 represents an acryloyl group or a methacryloyl group. 10 represents an alkylene group having 1 to 3 carbon atoms. 11 represents hydrogen or an alkyl group having 1 to 3 carbon atoms. is a monomer represented by Item 1. The dispersant for fluorine-based resin particles according to item 1. 4. The dispersant for fluorine-based resin particles according to item 1, wherein the Si—O bond-containing monomer has a number average molecular weight of 400 to 1,200. 5. The dispersant for fluorine-based resin particles according to item 1, wherein the weight ratio [A:B] of the Si—O bond-containing monomer (A) to the (meth)acryloyl group-containing monomer (B) is 5:5 to 8:2. 6. The dispersant for fluorine-based resin particles according to item 1, wherein the non-fluorine-based copolymer has a weight average molecular weight of 5,000 to 50,000. 7. The dispersant for fluororesin particles according to item 1, wherein the content of the non-fluorinated copolymer in the dispersant for fluororesin particles is 1 to 99% by weight. 8. The dispersant for fluororesin particles according to item 1, having a fluorine content of 1% by weight or less. 9. The dispersant for fluororesin particles according to item 1, wherein the organic solvent is at least one selected from the group consisting of propylene glycol monomethyl ether acetate, ethyl acetate, isopropyl alcohol, butyl acetate, methyl ethyl ketone, and acetone. 10. A dispersion liquid containing the dispersant according to any one of items 1 to 9 and fluorine-based resin particles. 11. A cured film obtained by curing a coating film of the dispersion according to item 10. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a non-fluorine-based dispersant that can provide excellent dispersibility equivalent to that of a fluorine-based dispersant in a dispersion liquid in which fluorine-based resin particles are dispersed.

[0015] In particular, the dispersant of the present invention uses a copolymer obtained by polymerizing a specific silicone acrylate and a hydrophilic monomer in a specific ratio, and therefore can obtain high dispersibility even with PTFE particles, which are considered to be relatively prone to aggregation (coagulation) among fluororesin particles.

[0016] In other words, the dispersant of the present invention is non-fluorinated but can exhibit high dispersibility equivalent to that of fluorinated dispersants, and therefore can be used as a substitute for fluorinated dispersants, thereby eliminating concerns about environmental or health problems caused by PFAS.

[0017] Furthermore, the dispersant of the present invention can be suitably used to disperse fluororesin particles in an organic solvent, and can therefore provide a dispersion of highly dispersible fluororesin particles. DETAILED DESCRIPTION OF THE INVENTION

[0018] 1. Dispersants for fluororesin particles The dispersant for fluororesin particles of the present invention (dispersant of the present invention) is a dispersant for dispersing fluororesin particles in a liquid, (1) A non-fluorine-containing copolymer (hereinafter also referred to as "the copolymer of the present invention") containing, as repeating units, (a) an Si-O bond-containing monomer having one polymerizable functional group in one molecule, the polymerizable functional group being a (meth)acryloyl group, and (b) a (meth)acryloyl group-containing monomer having one polymerizable functional group in one molecule, the polymerizable functional group being a (meth)acryloyl group (excluding the Si-O bond-containing monomer), and (2) Organic solvents The present invention is characterized by comprising:

[0019] In the present invention, unless otherwise specified, an acryloyl group or a methacryloyl group is collectively referred to as a "(meth)acryloyl group." An acryloyloxy group or a methacryloyloxy group is collectively referred to as a "(meth)acryloyloxy group." Furthermore, an acrylate or a methacrylate is collectively referred to as a "(meth)acrylate," and an acrylic acid or a methacrylic acid is collectively referred to as a "(meth)acrylic acid."

[0020] The dispersant of the present invention is a liquid containing the copolymer of the present invention and an organic solvent as described above, and is preferably in a state where the copolymer of the present invention is dissolved in the organic solvent (solution). In this case, a part of the copolymer of the present invention may be in a dispersed state without being dissolved, as long as the effect of the present invention is not impaired.

[0021] (1) Copolymer of the Present Invention (1-1) Constitution of the Copolymer of the Present Invention The copolymer of the present invention contains, as repeating units (monomer units), an Si-O bond-containing monomer (monomer A) having one polymerizable functional group in one molecule, the polymerizable functional group being a (meth)acryloyl group, and (b) a (meth)acryloyl group-containing monomer (excluding the Si-O bond-containing monomer) (monomer B) having one polymerizable functional group in one molecule, the polymerizable functional group being a (meth)acryloyl group.

[0022] The copolymer of the present invention is non-fluorine-based. That is, it is composed of a copolymer that does not contain fluorine atoms. This can also address the problem of PFAS. Therefore, neither Monomer A nor Monomer B contains fluorine atoms.

[0023] The copolymer of the present invention may be any of an alternating copolymer, a random copolymer, a block copolymer, and a graft copolymer, as long as it contains a predetermined ratio of monomer A and monomer B as described below. Furthermore, it may contain monomers other than monomers A and B, as long as the effects of the present invention are not impaired.

[0024] Monomer A is an Si-O bond-containing monomer having one polymerizable functional group in one molecule, the polymerizable functional group being a (meth)acryloyl group. Therefore, Monomer A has one (meth)acryloyl group in the molecule, which allows it to polymerize with Monomer B (the (meth)acryloyl group of Monomer B).

[0025] Monomer A may be any monomer as long as it has an Si-O bond, and it is particularly preferred that it has a siloxane bond (Si-O-Si). The Si-O bond may be one, or may have a repeating structure of two or more.

[0026] The groups bonded to the silicon atom and oxygen atom in the Si-O bond of monomer A are not limited as long as they are non-polymerizable groups, and suitable examples include alkyl groups, trialkylsilyl groups, trialkylsiloxy groups, etc. The number of carbon atoms in these non-polymerizable groups is not limited, but is usually sufficient if it is about 1 to 5, and particularly preferably 1 to 3.

[0027] In an embodiment of the present invention, the monomer A has the following general formula (1): [ka] (where m represents 1 to 5. R 1 represents an acryloyl group or a methacryloyl group. 21 and R 22 are the same or different and represent a trialkylsiloxy group or an alkyl group having 1 to 3 carbon atoms. 3 is a trialkylsiloxy group or a siloxane group of the following general formula (2): [ka] (where n is a number between 0 and 30. 4 ~R 8 are the same or different and represent an alkyl group having 1 to 4 carbon atoms. It is desirable that the monomer is represented by the formula:

[0028] In the general formula (1), the m indicates the number of repetitions of [-CH2-], and is usually 1 to 5, and preferably 1 to 3. The m may be an integer.

[0029] Above R 1 indicates an acryloyl group [H2C=CH-C(=O)-] or a methacryloyl group [H2C=C(CH3)-C(=O)-].

[0030] Above R 21 and R 22 are the same or different and represent a trialkylsiloxy group [e.g., a trimethylsiloxy group; (CH3)3SiO-] or an alkyl group having 1 to 3 carbon atoms (particularly an n-alkyl group). 21 and R 22 may both be a trialkylsiloxy group [for example, a trimethylsiloxy group; (CH3)3SiO-] or an alkyl group having 1 to 3 carbon atoms, or one may be a trialkylsiloxy group and the other an alkyl group having 1 to 3 carbon atoms.

[0031] Above R 3 represents a trialkylsiloxy group or a siloxane group of general formula (2). In the above general formula (2), n represents [—Si(R 4 )(R 5 )-O-] and is usually 0 to 30, preferably 0 to 15, and more preferably 0 to 10. The above n may be an integer.

[0032] Above R 21 , R 22 and R 3 Examples of the trialkylsiloxy group represented by the formula (I) include a trimethylsiloxy group, a triethylsiloxy group, and a tripropylsiloxy group, and a trimethylsiloxy group [(CH3)3SiO-] is particularly preferred.

[0033] Above R 4 ~R 8 are the same or different and represent an alkyl group having 1 to 4 carbon atoms (particularly an n-alkyl group).

[0034] The number average molecular weight of the monomer A is not limited as long as it has the above structure, but from the viewpoint of obtaining higher dispersibility, flowability, etc., it is usually preferably about 400 to 1200, more preferably 400 to 1000, and most preferably 400 to 500.

[0035] Monomer B is a (meth)acryloyl group-containing monomer (excluding the Si-O bond-containing monomer) that has one polymerizable functional group in one molecule, and the polymerizable functional group is a (meth)acryloyl group. In particular, as monomer B, a compound having a (meth)acryloyl group at the end of a polyalkylene oxide chain can be preferably used.

[0036] More specifically, the compound represented by the following general formula (3): [ka] (where y represents a value between 1 and 100. R 9 represents an acryloyl group or a methacryloyl group. 10 represents an alkylene group having 1 to 3 carbon atoms. 11 represents hydrogen or an alkyl group having 1 to 3 carbon atoms. It is preferable that the monomer is represented by the following formula:

[0037] The above y is [-OR 10 -] and is usually 1 to 100, preferably 1 to 50, and more preferably 1 to 15. The above y may be an integer. In the present invention, the greater the above repetition number, the higher the dispersibility tends to be.

[0038] Above R 9 represents an acryloyl group or a methacryloyl group.

[0039] Above R 10 represents an alkylene group having 1 to 3 carbon atoms. Therefore, alkylene groups having no substituents such as [-CH2-], [-CH2CH2-], and [-CH2CH2CH2-] can be suitably used.

[0040] Above R 11 represents hydrogen or an alkyl group (particularly an n-alkyl group) having 1 to 3 carbon atoms. Therefore, for example, hydrogen, a methyl group, etc. can also be suitably used.

[0041] The number average molecular weight of the monomer B is not limited as long as it has the above structure, but from the viewpoint of obtaining higher dispersibility, flowability, etc., it is usually preferably about 100 to 5000, more preferably 100 to 2500, and particularly preferably 100 to 1000.

[0042] The ratio of monomer A to monomer B in the copolymer of the present invention is not limited, but the weight ratio of monomer A to monomer B [A:B] is preferably 5:5 to 8:2, and more preferably 7:3 to 8:2. A copolymer composed of monomer A and monomer B in such a ratio can exhibit higher dispersibility, etc.

[0043] Furthermore, the molar ratio [A:B] of monomer A to monomer B in the copolymer of the present invention is not limited, but is preferably 4:6 to 9:1, more preferably 5:5 to 8.5:1.5, even more preferably 6:4 to 8.5:1.5, and most preferably 7:3 to 8.3:1.7. A copolymer constituted by monomer A and monomer B in such a ratio can exhibit higher dispersibility, etc.

[0044] The weight average molecular weight of the copolymer of the present invention is not particularly limited, but is usually preferably 5000 to 50000, and more preferably 7000 to 30000. By setting it within such a range, higher dispersibility and the like can be obtained.

[0045] (1-2) Method for producing the copolymer of the present invention The method for producing the copolymer of the present invention is not limited, and may be, for example, solution polymerization, emulsion polymerization, or the like. However, solution polymerization, which produces the copolymer of the present invention in a dissolved state, can be preferably employed.

[0046] for example, (1) a step of preparing a raw material solution containing (a) an Si-O bond-containing monomer (monomer A) having one polymerizable functional group in one molecule, the polymerizable functional group being a (meth)acryloyl group, and (b) a (meth)acryloyl group-containing monomer (excluding the Si-O bond-containing monomer) (monomer B) having one polymerizable functional group in one molecule, the polymerizable functional group being a (meth)acryloyl group, and an organic solvent (raw material solution preparation step); (2) A step of heating the raw material liquid at 50 to 90°C (heating step) The copolymer of the present invention can be suitably obtained by a production method including the steps of:

[0047] Raw material liquid preparation process In the raw material solution preparation step, a raw material solution containing monomer A, monomer B, and an organic solvent is prepared.

[0048] The monomer A and the monomer B can be the compounds described above in the ratios described above.

[0049] Monomer A used as a raw material can be a known or commercially available silicon compound (such as a silicone compound). Commercially available products include, for example, modified silicone oil (manufactured by Shin-Etsu Silicone Co., Ltd., product name "X-22-2404"), modified silicone oil (manufactured by Shin-Etsu Silicone Co., Ltd., product name "X-22-174ASX"), modified silicone oil (manufactured by Shin-Etsu Silicone Co., Ltd., product name "X-22-174BX"), modified silicone oil (manufactured by Shin-Etsu Silicone Co., Ltd., product name "X-22-2426"), 3-[tris(trimethylsilyloxy)silyl]propyl methacrylate (manufactured by TCI), monomethacrylate, Examples include oxypropyl-terminated polydimethylsiloxane (manufactured by Gelest, product name "MCR-M11"), monomethacryloxypropyl-terminated polydimethylsiloxane (manufactured by Gelest, product name "MCR-M17"), reactive polydimethylsiloxane (manufactured by JNC, product name "FM-0711"), reactive polydimethylsiloxane (manufactured by JNC, product name "FM-0721"), and reactive polydimethylsiloxane (manufactured by JNC, product name "FM-0725").

[0050] As the monomer B used as a raw material, a known or commercially available acrylic compound can be used. Commercially available products include glycerin monomethacrylate (NOF Corp., product name "Blenmer GLM"), 2-hydroxyethyl methacrylate (NOF Corp., product name "Blenmer E"), polyethylene glycol monomethacrylate (NOF Corp., product names "Blenmer PE-90", "Blenmer PE-200", "Blenmer PE-350"), polyethylene glycol monoacrylate (NOF Corp., product names "Blenmer AE-90", "Blenmer AE-200", "Blenmer AE-400"), hydroxypropyl methacrylate (NOF Corp., product name "Blenmer P"), polypropylene glycol monomethacrylate (NOF Corp., product names "Blenmer PP-1000", "Blenmer PP-500", "Blenmer PP-800", etc.), polypropylene glycol monoacrylate (NOF Corp., product names "Blenmer AP-150", "Blenmer AP-400", "Blenmer AP-550"), poly(ethylene glycol propylene glycol) )-monomethacrylate (manufactured by NOF Corp., product name "Blenmar 50PEP-300"), polyethylene glycol / polypropylene glycol-monomethacrylate (manufactured by NOF Corp., product name "Blenmar 70PEP-350B", etc.), poly(ethylene glycol / tetramethylene glycol)-monomethacrylate (manufactured by NOF Corp., product name "Blenmar 55PET-800"), poly(propylene glycol / tetramethylene glycol)-monomethacrylate (manufactured by NOF Corp., product name "Blenmar -PPT), propylene glycol-polybutylene glycol-monomethacrylate (NOF Corporation, product name "BLEMMER 10PPB-500B"), 2-hydroxyethyl acrylate (Osaka Organic Chemical Industry Co., Ltd., product name "HEA"), 2-hydroxypropyl acrylate (Osaka Organic Chemical Industry Co., Ltd., product name "HPA"), 4-hydroxybutyl acrylate (Nippon Kasei Chemical Industry Co., Ltd., product name "4HBA"), 1,4-cyclohexanedimethanol monoacrylate, etc.

[0051] The organic solvent may be any one that can dissolve the copolymer of the present invention to be obtained, and various organic solvents can be used, such as ester solvents such as ethyl acetate, butyl acetate, methoxybutyl acetate, and methoxypropyl acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ether solvents such as diethyl ether, dibutyl ether, tetrahydrofuran, propylene glycol monomethyl ether acetate, and diethylene glycol dimethyl ether; and aromatic solvents such as toluene and xylene. These can be used alone or in combination depending on the type of copolymer of the present invention to be obtained.

[0052] Furthermore, additives generally used in polymerization reactions, such as a polymerization initiator and a chain transfer agent, can be added to the raw material liquid as needed.

[0053] The mixing of the components can be carried out using a known mixer, stirrer, etc., as long as the components are mixed uniformly. After mixing, the components are preferably stirred for a certain period of time. The stirring time can be, for example, about 1 to 10 hours, but is not limited thereto.

[0054] During stirring, it is preferable to bubble the mixture with an inert gas such as nitrogen gas or argon gas. This allows dissolved oxygen to be effectively removed. The bubbling time can be, for example, about 10 to 60 minutes, but is not limited to this. A known or commercially available bubbling device may be used for bubbling.

[0055] heating process In the heating step, the raw material liquid is heated at 50 to 90° C. By heating, the polymerization reaction between the monomer A and the monomer B proceeds, and the copolymer of the present invention can finally be obtained.

[0056] The heating temperature may be generally in the range of 50 to 90° C. as described above, and is preferably in the range of 70 to 85° C. The heating time varies depending on the heating temperature and other factors, and may be set to a time sufficient for the polymerization reaction between monomer A and monomer B, and may be set, for example, within the range of about 3 to 10 hours.

[0057] The reaction product liquid obtained by heating is usually in the form of a solution in which the copolymer of the present invention is dissolved in an organic solvent. In this case, the reaction product liquid obtained can be used as the dispersant of the present invention as is, or, for example, any of a) a diluted solution obtained by further adding an organic solvent to the reaction product liquid obtained, b) a concentrated solution obtained by removing part of the organic solvent from the reaction product obtained, or c) a solution obtained by replacing part or all of the organic solvent in the reaction product obtained with another organic solvent can also be used as the dispersant of the present invention. In addition, the reaction product liquid obtained may be subjected to a known purification treatment, if necessary.

[0058] (2) Organic solvents The organic solvent in the dispersant of the present invention may be any organic solvent capable of dissolving the copolymer of the present invention, and may be, for example, at least one of ether solvents, ester solvents, alcohol solvents, ketone solvents, etc. Among these, at least one selected from propylene glycol monomethyl ether acetate, ethyl acetate, isopropyl alcohol, butyl acetate, methyl ethyl ketone, and acetone is particularly preferred.

[0059] The content of the organic solvent in the dispersant of the present invention is not limited, and may be within a range such that the content of the copolymer of the present invention is 1 to 99% by weight. Therefore, for example, a composition containing 20 to 60% by weight of the copolymer of the present invention and 40 to 80% by weight of the organic solvent may be adopted.

[0060] (3) Other ingredients The dispersant of the present invention may contain other components as long as the effects of the present invention are not impaired. Examples include various additives such as antioxidants and polymerization inhibitors. These additives may be contained in the dispersant of the present invention in a total amount of 10% by weight or less, preferably 5% by weight or less.

[0061] Furthermore, from the viewpoint of environmental protection, it is ideal for the dispersant of the present invention to be fluorine-free (i.e., a fluorine content of 0 wt%). However, since there is a possibility of unintentional contamination, such as impurities, a fluorine content of 1 wt% or less, preferably 0.1 wt% or less, is usually acceptable. The fluorine content can usually be calculated by multiplying the fluoride content (wt%) in the dispersant by (molecular weight of fluorine / molecular weight of fluoride). For example, if the fluoride is tin fluoride (SnF), the (molecular weight of fluorine / molecular weight of fluoride) ratio is 38 / 157.

[0062] 2. Manufacturing method of dispersant for fluororesin particles The dispersant of the present invention can be suitably produced by a method including a step of dissolving the copolymer of the present invention in an organic solvent.

[0063] As explained above in "(1-2) Production Method of the Copolymer of the Present Invention," the reaction product solution obtained during the production of the copolymer of the present invention can be used as a dispersant as is, or a dispersant can be prepared by adding, removing, or replacing an organic solvent. These operations themselves can be carried out according to known methods. They can also be carried out using known or commercially available equipment.

[0064] 3. Usage of dispersants for fluororesin particles The dispersant of the present invention can be suitably used as a dispersant for dispersing fluorine-based resin particles in a liquid.

[0065] The resin constituting the fluororesin particles is not limited as long as it is a fluorine-containing resin, and examples thereof include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), and various other fluorine-containing resins. These fluororesins may be publicly known or commercially available. In the present invention, the fluororesin may also be suitably used as a dispersant for PTFE particles, which are particularly prone to aggregation and difficult to disperse.

[0066] The average particle size of the fluororesin particles is not particularly limited and can be, for example, in the range of about 0.1 to 100 μm, but even fine particles with a maximum particle size of 1 μm or less can be dispersed effectively.

[0067] The dispersion medium may be any liquid that can disperse the fluororesin particles in the form of particles without substantially dissolving them, and examples thereof include various organic solvents such as methyl ethyl ketone, acetone, acetonitrile, dimethoxyethane, 1,3-dimethyl-2-imidazolidinone, methanol, ethanol, isopropyl alcohol, diethyl ether, ethyl acetate, butyl acetate, N-methyl-2-pyrrolidone, N,N-dimethylformamide, benzene, and toluene. These organic solvents can be used alone or in combination of two or more. Among these organic solvents, an appropriate solvent can be selected depending on the type of fluororesin particles to be dispersed, etc.

[0068] When dispersing fluororesin particles in these dispersion media, the dispersant of the present invention can be added to obtain a dispersion in which the fluororesin particles are dispersed in the dispersion media. Such dispersions containing fluororesin particles are also encompassed by the present invention. The amount of the dispersant of the present invention added should be sufficient to disperse the fluororesin particles in the dispersion media, but can be appropriately changed depending on the type and particle size of the fluororesin particles used, as well as the type of dispersion media used. For example, the amount can be set within the range of approximately 0.1 to 20 parts by weight per 100 parts by weight of the fluororesin particles, but is not limited thereto.

[0069] The dispersion liquid containing the fluororesin particles may contain other components, such as antioxidants and polymerization inhibitors, within the range that does not impair the effects of the present invention.

[0070] The dispersion of the present invention can be suitably used, for example, to form a fluorine-based cured film on the surface of various objects. Therefore, the present invention also encompasses a cured film obtained by curing (e.g., thermally curing) a coating film of the dispersion of the present invention.

[0071] The object (substrate) on which the cured film is formed is not limited as long as it can impart at least one of the properties possessed by fluororesins (heat resistance, lubricity, water and oil repellency, abrasion resistance, electrical insulation, etc.) Therefore, the material of the object may be, for example, metal or alloy, ceramics, resin, glass, fibrous material (paper, fiber, fabric, wood, etc.), cement (concrete), or a composite material thereof.

[0072] The object may be any of raw materials, semi-finished products (components, etc.), or finished products. Therefore, the dispersion of the present invention can be used as a fluorine-based coating agent applied to various products, such as a) a fluorine-based coating agent (lubricating paint or lubricating oil) used for lubrication of automobiles, office automation equipment, medical equipment, general industrial equipment, chemical plants, etc., b) a fluorine-based coating agent for surface protection (moisture prevention, etc.) of printed wiring boards, and c) a fluorine-based coating agent used in semiconductor manufacturing equipment (storage containers, pipes, valves, filters, sensors, etc.).

[0073] The cured film of the present invention can be suitably formed, for example, by a method including a step of forming a coating film by applying the dispersion of the present invention to the surface of an object, and a step of heating the obtained coating film.

[0074] The method for applying the dispersion of the present invention is not limited, and can be, for example, any of gravure coating, bar coating, wire bar coating, spin coating, doctor blade coating, dip coating, slit coating, etc. In these methods, coating can be carried out using a known or commercially available coating or printing device.

[0075] The coating film applied to the surface of the object can be subjected to a drying process prior to heating, if necessary. The drying process only needs to evaporate the organic solvent in the coating film, and can be natural drying or forced drying at, for example, about 50 to 250°C.

[0076] The coating film can then be heated to form a cured film. The heating temperature can be appropriately set depending on the type of fluororesin particles contained in the dispersion, the heat resistance of the target object, etc., but is usually preferably set within a range of about 300 to 420° C. The heating time varies depending on the heating temperature, etc., and can be, for example, about 30 seconds to 5 minutes, but is not limited to this.

[0077] The thickness of the cured film can be appropriately set depending on the desired properties (heat resistance, abrasion resistance, etc.) and the intended use of the object, but is usually about 0.01 to 100 μm, preferably about 0.1 to 10 μm. [Example]

[0078] The features of the present invention will be described in more detail below with reference to examples and comparative examples. However, the scope of the present invention is not limited to these examples. Note that "%" means "% by weight."

[0079] 1.Raw materials used In the production examples described below, the following raw materials were used. (1) Monomer A Monomer A1: molecular weight 423 (3-[tris(trimethylsilyloxy)silyl]propyl methacrylate manufactured by TCI) (formula X below) [ka] Monomer A2: molecular weight 1000, n=9 in the following formula A (MCR-M11, manufactured by Gelest) Monomer A3: molecular weight 5000, n=63 in the following formula A (manufactured by Gelest, MCR-M17) [ka]

[0080] (2) Monomer B AE-400: NOF Corporation, Blenmar AE-400, molecular weight = 513, in the following formula B, R1: H, R2: C2H4, R3: H, m = 10 AE-200: NOF Corporation, Blenmar AE-200, molecular weight = 270, in the following formula B, R1: H, R2: C2H4, R3: H, m = 4.5 PE-90: NOF Corporation, Blenmar PE-90, molecular weight = 174, in the following formula B, R1: H, R2: C2H4, R3: CH3, m = 2 AME-400: NOF Corporation, Blenmar AME-400, molecular weight = 483, in the following formula B, R1: CH3, R2: C2H4, R3: H, m = 9 PME-400: NOF Corporation, Blenmar PME-400, molecular weight = 496, in the following formula B, R1: CH3, R2: C2H4, R3: CH3, m = 9 PP-500: NOF Corporation, Blenmar PP-500, molecular weight = 609, in the following formula B, R1: H, R2: C3H6, R3: CH3, m = 9 [ka]

[0081] (3) PTFE powder KTL-500F: Kitamura Co., Ltd., maximum particle size 1 μm or less, PEFE powder

[0082] (4) Conventional dispersants KF-6011: Shin-Etsu Silicone Co., Ltd., polyether-modified silicone surfactant, main chain siloxane side chain: ethylene oxide (EO), HLB: 14.5 Futergent 710FL: Fluorine-based surfactant manufactured by Neos

[0083] (5) Organic solvents PGMEA: Propylene glycol monomethyl ether acetate NMP: N-methyl-2-pyrrolidone

[0084] 2. Manufacturing example Using the above raw materials, various copolymers were synthesized as follows.

[0085] [Manufacturing Example 1] Monomer A1 (7 g; 16.55 mmol), AE-400 (3 g; 5.86 mmol), PGMEA (10 g), dodecanethiol (hereinafter "LM", Fujifilm Wako Pure Chemical Industries, Ltd.) (0.178 g) as a chain transfer agent, and 2,2'-azobis(isobutyrate)dimethyl ester (hereinafter "V-601", Fujifilm Wako Pure Chemical Industries, Ltd.) (0.202 g) as a polymerization initiator were added to a 50 mL three-neck flask equipped with a stirrer. The reaction solution was stirred for 30 minutes while bubbling with nitrogen. The reaction solution was heated to 80 °C and stirred for 6 hours. The solution was diluted with PGMEA to a solids concentration of 30%. A dispersant was thus obtained. The weight-average molecular weight of the copolymer contained in the resulting dispersant was also measured. The results are shown in Table 1. Measurement was performed by gel permeation chromatography (GPC). The GPC device used was a "Prominence HLPC" manufactured by Shimadzu Corporation. One "α-5000" column manufactured by Tosoh Corporation was used. Tetrahydrofuran (THF) was used as the measurement solvent, and the column temperature was set to 40°C. The sample concentration was 1%, and 1 μL was injected and measured. A molecular weight calibration curve was created using standard polyethylene glycol (SE series manufactured by Tosoh Corporation).

[0086] [Manufacturing Examples 2 to 15] Dispersants were prepared in the same manner as in Production Example 1, except that the raw materials used and their ratios were changed as shown in Tables 1 and 2. The weight-average molecular weight of the copolymer contained in the resulting dispersant was measured in the same manner as in Production Example 1. The results are shown in Tables 1 and 2.

[0087] [Table 1]

[0088] [Table 2]

[0089] 3. Examples and Comparative Examples As shown in Tables 3 and 4, the dispersants obtained in the respective production examples were used to prepare dispersions in which fluorine-based resin particles were dispersed.

[0090] [Example 1] After dissolving a dispersant (0.5 g) in NMP (6.5 g), PTFE powder (3.0 g) was added. Dispersion was carried out for 30 minutes using an ultrasonic agitator to prepare a dispersion of the PTFE powder.

[0091] [Examples 2 to 9] A dispersion of PTFE powder was prepared in the same manner as in Example 1, except that the dispersant was changed as shown in Table 3 or Table 4.

[0092] [Comparative Examples 1 to 4] A dispersion of PTFE powder was prepared in the same manner as in Example 1, except that the dispersant was changed as shown in Table 4.

[0093] Comparative Example 5 As shown in Table 4, a dispersion of PTFE powder was prepared in the same manner as in Example 1, except that a commercially available non-fluorinated surfactant was used as the dispersant.

[0094] [Reference example 1] As shown in Table 4, a dispersion of PTFE powder was prepared in the same manner as in Example 1, except that a commercially available fluorine-based surfactant was used as the dispersant.

[0095] [Test Example 1] The PTFE powder dispersions prepared in the Examples, Comparative Examples, and Reference Examples were evaluated for the following items. The results are shown in Tables 3 and 4.

[0096] (1) Dispersibility The PTFE powder dispersion was visually observed. As a result, it was rated as "◎" if it was a uniform milky white color with no lumps (aggregates) visible, "〇" if it was a uniform milky white color but lumps were visible, and "×" if the PTFE powder dispersion was separated into milky white and transparent areas.

[0097] (2) Redispersibility After leaving the PTFE powder dispersion to stand for 4 days, the dispersion was stirred with a stirrer (MIX-ROTAR MR-5, AS ONE Corporation, stirring conditions: 48 rpm at 20°C), and the time until the solids on the bottom surface disappeared was measured. If the time was within 1 hour, it was evaluated as "◎", if it was within 3 hours, it was evaluated as "◯", and if it was more than 3 hours, it was evaluated as "×".

[0098] (3) Liquidity The PTFE powder dispersion was gently shaken by hand, and the fluidity of the PTFE powder dispersion was visually confirmed. If the liquid was thin and moved when gently shaken, it was rated as "◎", if the liquid was highly viscous but moved when gently shaken, it was rated as "〇", and if the liquid was thick and did not move when shaken, it was rated as "×".

[0099] [Table 3]

[0100] [Table 4]

[0101] As is clear from the results in Tables 3 and 4, the PTFE powder dispersion using the dispersant of the present invention not only has excellent dispersibility of PTFE particles, but also exhibits excellent performance in terms of redispersibility and fluidity. In particular, it is found that the copolymer of a silicone acrylate monomer (monomer A) and a hydrophilic monomer (monomer B) is highly effective in dispersing PTFE particles, has better dispersibility than conventional silicone surfactants, and exhibits dispersibility equivalent to that of fluorine-based surfactants.

[0102] The results of Comparative Example 5 show that the PTFE powder dispersion of the present invention is superior in dispersibility to conventional silicone surfactants (for example, Patent Documents 3 and 4).

[0103] Comparing Examples 1 and 6 with Comparative Example 2, it is clear that the smaller the molecular weight of the silicone acrylate monomer, the better the dispersibility.

[0104] Comparing Examples 1, 7, and 8, it is clear that the longer the EO chain, the better the dispersibility. Comparing Examples 1, 4, and 5 with Comparative Examples 3 and 4, it is clear that dispersibility is particularly good when the silicone acrylate monomer ratio (weight ratio) is 5 / 5 to 8 / 2 (particularly 7 / 3 to 8 / 2).

Claims

1. A dispersant for dispersing fluorine-based resin particles in a liquid, (1) A non-fluorine-containing copolymer containing, as repeating units, (a) an Si—O bond-containing monomer having one polymerizable functional group in one molecule, the polymerizable functional group being a (meth)acryloyl group, and (b) a (meth)acryloyl group-containing monomer having one polymerizable functional group in one molecule, the polymerizable functional group being a (meth)acryloyl group (excluding the Si—O bond-containing monomer); and (2) Organic solvents A dispersant for fluorine-based resin particles, comprising:

2. The Si—O bond-containing monomer is represented by the following general formula (1): 【Chemistry 10】 (where m represents 1 to 5. R １ represents an acryloyl group or a methacryloyl group. ２１ and R ２２ are the same or different and represent a trialkylsiloxy group or an alkyl group having 1 to 3 carbon atoms. ３ is a trialkylsiloxy group or a siloxane group of the following general formula (2): 【Chemistry 11】 (where n is a number between 0 and 30. ４ ~R ８ are the same or different and represent an alkyl group having 1 to 4 carbon atoms. is a monomer represented by The dispersant for fluorine-based resin particles according to claim 1 .

3. The (meth)acryloyl group-containing monomer is represented by the following general formula (3): 【Chemistry 12】 (where y represents 1 to 100. R ９ represents an acryloyl group or a methacryloyl group. １０ represents an alkylene group having 1 to 3 carbon atoms. １１ represents hydrogen or an alkyl group having 1 to 3 carbon atoms. is a monomer represented by The dispersant for fluorine-based resin particles according to claim 1 .

4. 2. The dispersant for fluorine-based resin particles according to claim 1, wherein the number average molecular weight of the Si—O bond-containing monomer is 400 to 1,200.

5. 2. The dispersant for fluorine-based resin particles according to claim 1, wherein a weight ratio [A:B] of the Si—O bond-containing monomer (A) to the (meth)acryloyl group-containing monomer (B) is 5:5 to 8:

2.

6. 2. The dispersant for fluorine-based resin particles according to claim 1, wherein the weight average molecular weight of the non-fluorine-based copolymer is 5,000 to 50,000.

7. 2. The dispersant for fluororesin particles according to claim 1, wherein the content of said non-fluorinated copolymer in the dispersant for fluororesin particles is 1 to 99% by weight.

8. 2. The dispersant for fluororesin particles according to claim 1, having a fluorine content of 1% by weight or less.

9. 2. The dispersant for fluororesin particles according to claim 1, wherein the organic solvent is at least one selected from the group consisting of propylene glycol monomethyl ether acetate, ethyl acetate, isopropyl alcohol, butyl acetate, methyl ethyl ketone, and acetone.

10. A dispersion comprising the dispersant according to any one of claims 1 to 9 and fluorine-based resin particles.

11. A cured film obtained by curing a coating film of the dispersion according to claim 10.

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