Dispersant for fluoropolymer 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] This invention relates to a novel dispersant for fluororesin particles. [Background technology]

[0002] Fluorine-based resins, including polytetrafluoroethylene (PTFE), are used as surface coating layers (cured films) for various products such as cooking utensils, containers, office automation equipment and other daily necessities, valves, bearings and other mechanical parts, and chemical tanks and other electronic equipment manufacturing equipment, due to their excellent heat resistance, chemical resistance, and lubricity. Generally, these surface coating layers are formed by using a dispersion of fluoroelastomer particles in an organic solvent as a coating solution, applying it to the surface of an object, and drying it.

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

[0004] However, in recent years, due to environmental concerns related to so-called PFAS (a group of compounds consisting of perfluoroalkyl and polyfluoroalkyl compounds), the development of non-fluorinated dispersants has been progressing.

[0005] For example, a polyoxyalkylene-modified polydimethylsiloxane has been proposed in which the weight-average molecular weight is 3000 or less and the HLB value calculated from the Griffin formula is between 1 and 18 (Patent Document 3).

[0006] Another method, for example, involves using a nonionic silicone-based surfactant as a dispersant (Patent Document 4).

[0007] In addition, a method is known in which a water-soluble polymer containing polydopamine and amino groups is used to improve the dispersibility of fluororesin particles (Patent Document 5). [Prior art documents]

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problem to be Solved by the Invention

[0009] However, while conventional silicone-based surfactants can provide a certain level of dispersibility, their performance is lower than that of existing fluorine-based dispersants, making them insufficient as a substitute for fluorine-based dispersants.

[0010] On the other hand, recently, as environmental issues caused by PFAS in, for example, rivers in Japan have been widely highlighted, concerns over the effects of PFAS on the human body, animals, and plants have further expanded, and the development of fluorine-free dispersants is therefore regarded as an urgent task.

[0011] Accordingly, the present invention is to provide a non-fluorine-based dispersant that exhibits excellent dispersibility equivalent to that of a fluorine-based dispersant in a dispersion liquid in which fluororesin particles are dispersed.

Means for Solving the Problem

[0012] As a result of extensive and intensive studies in view of the problems of the prior art, the present inventors have found that a composition containing a specific non-fluorine copolymer component can achieve the above object, and have completed the present invention.

[0013] That is, the present invention relates to the following dispersant for fluororesin particles. 1. A dispersant for dispersing fluororesin particles in a liquid, (1) a non-fluorinated copolymer comprising, as repeating units, (a) a Si-O bond-containing monomer having one polymerizable functional group in one molecule, wherein the polymerizable functional group is a (meth)acryloyl group, and (b) a (meth)acryloyl group-containing monomer having one polymerizable functional group in one molecule, wherein the polymerizable functional group is a (meth)acryloyl group (provided that the Si-O bond-containing monomer is excluded), and (2) an organic solvent A dispersant for fluororesin particles, comprising the same. 2. The Si-O bond-containing monomer is represented by the following general formula (1):

Chemical Formula

Chemical Formula

Chemical Formula

[0014] According to the present invention, it is possible to provide a non-fluorinated dispersant that provides excellent dispersibility equivalent to that of a fluorinated dispersant in a dispersion of fluorinated resin particles.

[0015] In particular, since the dispersant of the present invention uses a copolymer obtained by polymerizing a specific silicone acrylate and a hydrophilic monomer in a specific ratio, high dispersibility can be obtained 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, yet exhibits high dispersibility equivalent to that of fluorinated dispersants. Therefore, it can be used as a substitute for fluorinated dispersants, thereby resolving concerns about environmental or health problems caused by PFAS.

[0017] Furthermore, since the dispersant of the present invention can be suitably used to disperse fluororesin particles in an organic solvent, it can also provide a highly dispersible dispersion of fluororesin particles. [Modes for carrying out the invention]

[0018] 1. Dispersant for fluoropolymer 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 nonfluorinated copolymer (hereinafter also referred to as the "Copolymer of the present invention") comprising as repeating units (a) a Si-O bond-containing monomer having one polymerizable functional group in one molecule, wherein the polymerizable functional group is a (meth)acryloyl group, and (b) a (meth)acryloyl group-containing monomer having one polymerizable functional group in one molecule, wherein the polymerizable functional group is a (meth)acryloyl group (excluding the Si-O bond-containing monomer), and (2) Organic solvents It is characterized by including.

[0019] In this invention, unless otherwise specified, acryloyl groups or methacryloyl groups are collectively referred to as "(meth)acryloyl groups." Acryloyloxy groups or methacryloyloxy groups are collectively referred to as "(meth)acryloyloxy groups." Furthermore, acrylates or methacrylates are collectively referred to as "(meth)acrylates," and acrylic acid or methacrylic acid are collectively referred to as "(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 preferably the copolymer of the present invention is dissolved in the organic solvent (solution). In this case, a portion of the copolymer of the present invention may remain dispersed without dissolving, as long as it does not hinder the effects of the present invention.

[0021] (1) Copolymer of the present invention (1-1) Composition of the copolymer of the present invention The copolymer of the present invention comprises, as repeating units (monomer units), a Si-O bond-containing monomer (monomer A) having one polymerizable functional group in one molecule, wherein the polymerizable functional group is a (meth)acryloyl group, and (b) a (meth)acryloyl group-containing monomer (excluding the Si-O bond-containing monomer) having one polymerizable functional group in one molecule, wherein the polymerizable functional group is a (meth)acryloyl group.

[0022] The copolymer of the present invention is non-fluorinated; that is, it is composed of copolymers that do not contain fluorine atoms. This allows it to address the PFAS problem. Therefore, both monomer A and monomer B do not contain fluorine atoms.

[0023] The copolymer of the present invention may contain monomer A and monomer B in predetermined proportions, as described below, and may take any form, for example, an alternating copolymer, a random copolymer, a block copolymer, or a graft copolymer. Furthermore, monomers other than monomers A and B may be included, as long as they do not hinder the effects of the present invention.

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

[0025] Monomer A may have any Si-O bond, and is particularly preferably a siloxane bond (Si-O-Si). The Si-O bond may be a single bond or a repeating structure of two or more bonds.

[0026] The groups that bond to the silicon and oxygen atoms in the Si-O bond of monomer A are not limited as long as they are nonpolymerizable groups, and suitable examples include alkyl groups, trialkylsilyl groups, and trialkylsiloxy groups. The number of carbon atoms in these nonpolymerizable groups is not limited, but is usually around 1 to 5, and particularly preferably 1 to 3.

[0027] In embodiments of the present invention, monomer A is of the following general formula (1): [ka] (However, m represents 1 to 5. R 1 R represents an acryloyl group or a methacryloyl group. 21 and R 22 These represent a trialkylsiloxy group or an alkyl group having 1 to 3 carbon atoms, and are either identical or different from each other. 3 This is a trialkylsiloxy group or a siloxane group of the following general formula (2). [ka] (However, n represents 0 to 30. R 4 ~R 8 These represent alkyl groups having 1 to 4 carbon atoms, which are either identical or different from each other. It is preferable that the monomer is represented by .

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

[0029] The above R 1 This represents an acryloyl group [H2C=CH-C(=O)-] or a methacryloyl group [H2C=C(CH3)-C(=O)-].

[0030] The above R 21 and R 22 These are identical or different from each other, representing a trialkylsiloxy group [e.g., trimethylsiloxy group; (CH3)3SiO-] or an alkyl group having 1 to 3 carbon atoms (especially an n-alkyl group). Therefore, for example, R 21 and R 22 Both may be trialkylsiloxy groups [e.g., trimethylsiloxy group; (CH3)3SiO-] or alkyl groups having 1 to 3 carbon atoms, or one may be a trialkylsiloxy group and the other may be an alkyl group having 1 to 3 carbon atoms.

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

[0032] The above R 21 , R 22 and R 3 Examples of the trialkylsiloxy group shown include trimethylsiloxy group, triethylsiloxy group, and tripropylsiloxy group, with trimethylsiloxy group [(CH3)3SiO-] being particularly preferred.

[0033] The above R 4 ~R 8 These represent alkyl groups (especially n-alkyl groups) having 1 to 4 carbon atoms, which are either identical or different from each other.

[0034] The number-average molecular weight of monomer A is not limited as long as it has the above structure, but from the viewpoint of obtaining higher dispersibility, fluidity, etc., it is usually preferably around 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) having one polymerizable functional group in one molecule, wherein the polymerizable functional group is a (meth)acryloyl group. In particular, a compound having a (meth)acryloyl group at the end of a polyalkylene oxide chain can be suitably used as monomer B.

[0036] More specifically, see the general formula (3) below: [ka] (However, y represents a range from 1 to 100. R 9 R represents an acryloyl group or a methacryloyl group. 10 This indicates an alkylene group with 1 to 3 carbon atoms. 11 (This represents hydrogen or an alkyl group having 1 to 3 carbon atoms.) It is preferable that the monomer is represented by .

[0037] The above y is [-OR 10 This indicates the number of repetitions of -], which is usually between 1 and 100, preferably between 1 and 50, and more preferably between 1 and 15. The above y may be an integer. In this invention, there is a tendency for higher variance to be obtained as the above number of repetitions increases.

[0038] The above R 9 This represents an acryloyl group or a methacryloyl group.

[0039] The above R 10 This represents an alkylene group having 1 to 3 carbon atoms. Therefore, alkylene groups without substituents, such as [-CH2-], [-CH2CH2-], and [-CH2CH2CH2-], can be suitably used.

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

[0041] The number-average molecular weight of monomer B is not limited as long as it has the above structure, but from the viewpoint of obtaining higher dispersibility, fluidity, etc., it is usually preferably around 100 to 5000, more preferably 100 to 2500, and even more 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 [A:B] of monomer A to monomer B is preferably 5:5 to 8:2, and more preferably 7:3 to 8:2. Copolymers composed of monomer A and monomer B in such a ratio can exhibit higher dispersibility and other properties.

[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. Copolymers composed of monomer A and monomer B in such ratios can exhibit higher dispersibility and other properties.

[0044] The weight-average molecular weight of the copolymer of the present invention is not limited, but is usually preferably 5,000 to 50,000, and more preferably 7,000 to 30,000. Setting it within this range allows for higher dispersibility and other properties to 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 include, for example, solution polymerization or emulsion polymerization, but solution polymerization, in which the copolymer is obtained in a dissolved state, can be preferably employed.

[0046] for example, (1) A step of preparing a raw material solution containing (a) a Si-O bond-containing monomer (monomer A) having one polymerizable functional group in one molecule and the polymerizable functional group being a (meth)acryloyl group, and (b) a (meth)acryloyl group-containing monomer (monomer B) having one polymerizable functional group in one molecule and the polymerizable functional group being a (meth)acryloyl group (excluding the Si-O bond-containing monomer) 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 manufacturing method that includes [the specified ingredient].

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

[0048] Monomer A and monomer B can be the compounds described above, respectively, in the proportions described above.

[0049] Monomer A used as a raw material can be a known or commercially available silicon compound (silicone compound, etc.). Examples of commercially available products include 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), monomethacrylic acid Examples include oxypropyl-terminated polydimethylsiloxane (Gelest, product name "MCR-M11"), monomethacrylateoxypropyl-terminated polydimethylsiloxane (Gelest, product name "MCR-M17"), reactive polydimethylsiloxane (JNC, product name "FM-0711"), reactive polydimethylsiloxane (JNC, product name "FM-0721"), and reactive polydimethylsiloxane (JNC, product name "FM-0725").

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

[0051] Any organic solvent capable of dissolving the resulting copolymer of the present invention is acceptable. Examples include 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 individually or in combination of two or more, depending on the type of copolymer obtained.

[0052] Furthermore, the raw material liquid may contain additives commonly used in polymerization reactions, such as polymerization initiators and chain transfer agents, as needed.

[0053] The mixing of each component only needs to be done so that each component is uniformly mixed, and this can be done using known mixing devices, stirring devices, etc. Furthermore, it is preferable to stir for a certain period of time after mixing. The stirring time can be, for example, 1 to 10 hours, but is not limited to this.

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

[0055] heating process In the heating step, the raw material liquid is heated to 50-90°C. Heating causes the polymerization reaction between monomer A and monomer B to proceed, ultimately yielding the copolymer of the present invention.

[0056] The heating temperature can generally be in the range of 50 to 90°C, as described above, but it is particularly preferable to set it to 70 to 85°C. The heating time will vary depending on the heating temperature, etc., and should be sufficient for the polymerization reaction between monomer A and monomer B to occur. For example, it can be set within a range of about 3 to 10 hours.

[0057] The reaction product 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 obtained reaction product can be used as is as the dispersant of the present invention, or any of the following can be used as the dispersant of the present invention: a) a diluted solution obtained by further adding an organic solvent to the obtained reaction product, b) a concentrated solution obtained by removing some of the organic solvent from the obtained reaction product, or c) a solution obtained by replacing some or all of the organic solvent in the reaction product with another organic solvent. Furthermore, if necessary, the obtained reaction product may be subjected to a known purification treatment.

[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 at least one of the following can be used: ether-based solvents, ester-based solvents, alcohol-based solvents, ketone-based 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 should 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 can also be used.

[0060] (3) Other ingredients The dispersant of the present invention may contain other components as long as they do not interfere with the effects of the present invention. Examples include various additives such as antioxidants and polymerization inhibitors. These additives may be included 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 an environmental protection standpoint, it is ideal for the dispersant of the present invention to be fluorine-free (i.e., have a fluorine content of 0% by weight). However, since unintended contamination, such as impurities, can occur, a fluorine content of 1% by weight or less, preferably 0.1% by weight or less, is generally acceptable. The fluorine content can usually be calculated by multiplying the fluoride content in the dispersant (by weight) by (molecular weight of fluorine / molecular weight of fluoride). For example, if the fluoride is tin fluoride (SnF2), then (molecular weight of fluorine / molecular weight of fluoride) would be 38 / 157.

[0062] 2. Method for producing a dispersant for fluorine-based resin particles The dispersant of the present invention can be suitably produced by a method that includes the step of dissolving the copolymer of the present invention in an organic solvent.

[0063] As described in "(1-2) Method for Producing the Copolymer of the Present Invention," the organic solvent can be used as a dispersant directly from the reaction product obtained during the production of the copolymer of the present invention, or a dispersant can be prepared by adding, removing, or substituting 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. Forms of use of dispersants for fluororesin particles The dispersant of the present invention can be suitably used as a dispersant for dispersing fluororesin particles in a liquid.

[0065] The resin constituting the fluorine-based resin particles is not limited to any resin containing fluorine, and examples 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 fluorine-based resins can be known or commercially available. In the present invention, it can 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 in the range of, for example, 0.1 to 100 μm, but even fine particles with a maximum particle size of 1 μm or less can be effectively dispersed.

[0067] The dispersion medium can be any liquid that can disperse the fluororesin particles in particle form without substantially dissolving them. Examples of such liquids include 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 individually or in combination of two or more. From these organic solvents, appropriate selections can be made depending on the type of fluororesin particles to be dispersed.

[0068] By incorporating the dispersant of the present invention when dispersing fluororesin particles in these dispersion media, a dispersion liquid in which fluororesin particles are dispersed in the dispersion media can be obtained. Such a dispersion liquid containing fluororesin particles is also included in the present invention. The amount of dispersant of the present invention added should be sufficient to disperse the fluororesin particles in the dispersion media, but it 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, it can be set in the range of about 0.1 to 20 parts by weight per 100 parts by weight of fluororesin particles, but is not limited to this range.

[0069] Furthermore, the dispersion containing fluorine-based resin particles may also contain other components, as long as they do not interfere with the effects of the present invention. Examples of other components include antioxidants and polymerization inhibitors.

[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, a cured film obtained by curing (e.g., thermal curing) a coating film of the dispersion of the present invention is also included in the present invention.

[0071] The object (substrate) on which the cured film is formed is not limited as long as it can be given at least one of the properties of fluororesins (heat resistance, lubricity, water / oil repellency, abrasion resistance, electrical insulation, etc.). For this reason, the material of the object may be any of the following: metal or alloy, ceramics, resin, glass, fibrous materials (paper, fibers, fabric, wood, etc.), cement (concrete), or composite materials thereof.

[0072] Furthermore, the target material may be a raw material, a semi-finished product (parts, etc.), or a finished product. Therefore, the dispersion of the present invention can be used as a fluorine-based coating agent applied to various products, such as a) fluorine-based coating agents (lubricating paints or lubricating oils) used for lubrication in automobiles, office automation equipment, medical equipment, general industrial equipment, chemical plants, etc., b) fluorine-based coating agents for surface protection (moisture prevention, etc.) of printed circuit boards, and c) fluorine-based coating agents used in semiconductor manufacturing equipment (storage containers, pipes, valves, filters, sensors, etc.).

[0073] A cured film can be suitably formed by a method that includes, for example, the steps of applying the dispersion of the present invention to the surface of an object to form a coating film, and heating the obtained coating film.

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

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

[0076] Next, the coating can be cured by heating. The heating temperature can be set appropriately depending on the type of fluororesin particles contained in the dispersion, the heat resistance of the object, etc., but it is generally preferable to set it within the range of 300 to 420°C. The heating time varies depending on the heating temperature, etc., and can be, for example, 30 seconds to 5 minutes, but is not limited to this.

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

[0078] Examples and comparative examples are shown below to more specifically describe the features of the present invention. However, the scope of the present invention is not limited to the examples. Note that "%" means "weight %".

[0079] 1.Raw materials used The following raw materials were used in the manufacturing examples described later. (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 formula A below (Gelest, MCR-M11) • Monomer A3: Molecular weight 5000, n=63 in formula A below (Gelest, MCR-M17) [ka]

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

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

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

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

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

[0085] [Manufacturing Example 1] In a 50 mL three-necked flask containing a stirring bar, monomer A1 (7 g; 16.55 mmol), AE-400 (3 g; 5.86 mmol), PGMEA (10 g), dodecanethiol (hereinafter "LM", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (0.178 g) as a chain transfer agent, and 2,2'-azobis(isobutyrate)dimethyl (hereinafter "V-601", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (0.202 g) as a polymerization initiator were added, and 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 solid content concentration of 30%. A dispersant was thus obtained. Furthermore, the weight-average molecular weight of the copolymer contained in the obtained dispersant was measured. The results are shown in Table 1. The measurement method was gel permeation chromatography (GPC). A Shimadzu Corporation "ProminenceHLPC" GPC instrument was used. One Tosoh Corporation "α-5000" column 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 for measurement. A molecular weight calibration curve was created using standard polyethylene glycol (Tosoh Corporation, SE series).

[0086] [Manufacturing Examples 2-15] The dispersant was prepared in the same manner as in Production Example 1, except that the raw materials and their ratios were changed as shown in Tables 1 and 2. The weight-average molecular weight of the copolymer contained in the obtained dispersant was also 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, dispersions were prepared by dispersing fluororesin particles using the dispersants obtained in each manufacturing example.

[0090] [Example 1] After dissolving a dispersant (0.5g) in NMP (6.5g), PTFE powder (3.0g) was added. A dispersion of PTFE powder was prepared by dispersing it using an ultrasonic stirrer for 30 minutes.

[0091] [Examples 2-9] 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 1-4] 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 a 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 a 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. The results were evaluated as follows: "◎" if it exhibited a uniform milky white color with no clumps (aggregates); "〇" if it exhibited a uniform milky white color but clumps were observed; and "×" if the PTFE powder dispersion separated into a milky white portion and a transparent portion.

[0097] (2) Redispersibility After allowing the PTFE powder dispersion to stand for 4 days, the dispersion was stirred using a stirrer (MIX-ROTAR MR-5, manufactured by AS ONE Corporation, stirring conditions: 48 rpm at 20°C), and the time until the solid at the bottom disappeared was measured. If the time was less than 1 hour, it was evaluated as "◎", if it was less than 3 hours, it was evaluated as "〇", and if it exceeded 3 hours, it was evaluated as "×".

[0098] (3) Liquidity The fluidity of the PTFE powder dispersion was visually inspected by gently shaking it by hand. A "◎" rating indicated that the liquid was free-flowing and moved when gently shaken, a "〇" rating indicated that the liquid was highly viscous but still moved when gently shaken, and a "×" rating indicated that the liquid was thick and did not move even when shaken.

[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 exhibits excellent dispersibility of PTFE particles, as well as superior redispersibility and fluidity. In particular, the copolymer of silicone acrylate monomer (monomer A) and hydrophilic monomer (monomer B) is highly effective in dispersing PTFE particles, exhibiting better dispersibility than conventional silicone-based surfactants and comparable dispersibility to fluorine-based surfactants.

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

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

[0104] Comparing Examples 1, 7, and 8, it can be seen that the longer the EO chain, the better the dispersibility. A comparison of Examples 1, 4, and 5 with Comparative Examples 3 and 4 reveals that dispersibility is particularly good when the silicone acrylate monomer ratio (by weight) is 5 / 5 to 8 / 2 (especially 7 / 3 to 8 / 2).

Claims

1. A dispersant for dispersing fluororesin particles in a liquid, (1) A nonfluorine copolymer comprising as repeating units (a) an Si-O bond-containing monomer having one polymerizable functional group in one molecule, wherein the polymerizable functional group is a (meth)acryloyl group, and (b) a (meth)acryloyl group-containing monomer having one polymerizable functional group in one molecule, wherein the polymerizable functional group is a (meth)acryloyl group (excluding the Si-O bond-containing monomer), and (2) an organic solvent, The Si-O bond-containing monomer is given by the following general formula (1): 【Chemistry 10】 (However, m represents 1 to 5. R1 represents an acryloyl group or a methacryloyl group. R21 and R22 are the same or different from each other and represent a trialkylsiloxy group or an alkyl group having 1 to 3 carbon atoms. R3 represents a trialkylsiloxy group or a siloxane of the following general formula (2) 【Chemistry 11】 (However, n represents 0 to 30. R4 to R8 are identical or different alkyl groups having 1 to 4 carbon atoms.) It is monomer A, represented by , with a number-average molecular weight of 400 to 1200, The above (meth)acryloyl group-containing monomer is the following general formula (3): 【Chemistry 12】 (However, y represents 1 to 100. R9 represents an acryloyl group or a methacryloyl group. R10 represents an alkylene group having 1 to 3 carbon atoms. R11 represents hydrogen or an alkyl group having 1 to 3 carbon atoms.) This is monomer B represented by, A dispersant for fluororesin particles, wherein the weight ratio [A:B] of monomer A to monomer B is 5:5 to 8:

2.

2. The fluorine-based resin dispersant according to claim 1, wherein the number-average molecular weight of monomer B is 100 to 5000.

3. The dispersant for fluororesin particles according to claim 1, wherein the weight ratio [A:B] of monomer A to monomer B is 7:3 to 8:

2.

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

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

6. A dispersant for fluorine-based resin particles according to claim 1, wherein the fluorine content is 1% by weight or less.

7. The dispersant for fluorine-based resin particles according to claim 1, wherein the organic solvent is at least one selected from propylene glycol monomethyl ether acetate, ethyl acetate, isopropyl alcohol, butyl acetate, methyl ethyl ketone, and acetone.

8. A dispersion comprising a dispersant according to any one of claims 1 to 7 and fluororesin particles.

9. A cured film obtained by curing a coating film of the dispersion liquid described in Claim 8.

10. A raw material, semi-finished product, or finished product having formed the cured film described in Claim 9.

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