Fluororesin particle and method for producing the same

Abstract

To provide fluororesin particles which are excellent in flowability and filling property, and a method for producing fluororesin particles.SOLUTION: Resin particles contain a residue unit represented by the following general formula (1), and have a volume average particle diameter of 5 μm or more and 2,000 μm or less. In the formula (1), Rf1, Rf2, Rf3 and Rf4 each independently represent one selected from the group consisting of a fluorine atom, a 1C to 7C linear perfluoroalkyl group, a 3C to 7C branched perfluoroalkyl group and a 3C to 7C cyclic perfluoroalkyl group. The perfluoroalkyl group may have an ethereal oxygen atom. Rf1, Rf2, Rf3 and Rf4 may be connected to each other and may form a ring having 4 or more and 8 or less carbon atoms, and the ring may be a ring containing the ethereal oxygen atom.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to fluororesin particles having excellent flowability and packing properties, and a method for producing the same. [Background technology]

[0002] Fluorine-based resins have excellent electrical properties, chemical resistance, waterproofness, and liquid and oil repellency, so they are used in protective films for semiconductors and other electronic components, water-repellent films for inkjet printer heads, and waterproof and oil-resistant coatings for filters.

[0003] Among them, fluororesins containing oxolane rings have a bulky ring structure, making them amorphous and highly transparent and heat resistant. In addition, because they are composed only of carbon, fluorine, and oxygen, they have high electrical properties, chemical resistance, waterproofness, and liquid and oil repellency. Furthermore, because they are amorphous, they can be melt-molded.

[0004] Patent Document 1 describes a polymer of perfluoro(2-methylene-4-methyl-1,3-dioxolane (PFMMD) as a fluororesin containing an oxolane ring and a method for producing the same. Example 2 of Patent Document 1 describes an example in which a polymer of perfluoro(2-methylene-4-methyl-1,3-dioxolane) was polymerized in the coexistence of nitrogen fluoride (NF) in a sealed glass tube. In this example, no solvent was used, and no description was given of the specific form of the obtained polymer. Non-Patent Document 1 describes the bulk polymerization or solution polymerization of PFMMD as a fluororesin containing an oxolane ring to obtain the polymer. In this specification, unless otherwise specified, resin and polymer are described as having the same meaning. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 3,308,107 [Non-patent literature]

[0006] [Non-Patent Document 1] Macromolecules 2005, 38, 4237 Summary of the Invention [Problem to be solved by the invention]

[0007] Non-Patent Document 1 describes that in the case of bulk polymerization, if purification is not performed after polymerization, the optical properties and heat resistance of the resin will decrease, but these decreases can be reduced by purification. In solution polymerization, polymerization is performed using one of two types of fluorine-based solvents, and then chloroform is added to cause precipitation. There is no description of the specific form of the resin after purification from bulk polymerization and the resin obtained by precipitation by adding chloroform.

[0008] As a result of the study by the present inventors, the resin obtained by the method described in Patent Document 1 and Non-Patent Document 1 had an amorphous, non-particulate form. Therefore, there was a problem with the flowability of the resin. For example, when melt-molding the resin, it was found that problems with handling occurred, such as difficulty in continuously supplying the resin into the inside of a molding machine. Furthermore, since the resin described in Patent Document 1 and Non-Patent Document 1 has the above form, it was also found that, for example, when filling the resin into a molding machine, the desired weight of the resin cannot be filled for a given volume, that is, the filling ability is low. In this respect, a container with a large volume relative to the weight of the resin is required, so there was also a problem that the economy of transporting the article was low.

[0009] In order to solve the above problems, the present invention has an object to provide resin particles having excellent flowability and filling properties and containing a residue unit represented by general formula (1), and a method for producing the same.

[0010] Further, as a result of further investigations by the present inventors, the resins produced by the methods described in Patent Document 1 and Non-Patent Document 1 have an amorphous, non-particulate form, so that it is difficult to remove the solvent that is taken into the resin. If the solvent remains in the resin, the weight loss during heating is large, and there are problems such as foaming during molding and the like, and deterioration of the working environment during molding.

[0011] Therefore, it is another object of the present invention to provide resin particles containing a residue unit represented by general formula (1), which not only have excellent fluidity and filling properties but also have a small amount of weight loss on heating, and a method for producing the same.

[0012] In addition, in the production of fluororesins, resin particles can generally be obtained by means of emulsion polymerization, suspension polymerization, etc. However, in these methods, an emulsifier or dispersant is used as a polymerization aid. However, the emulsifier or dispersant used remains inside the resin particles, becoming a foreign matter, and furthermore, may cause coloring when the resin is heated, and may impair transparency and heat resistance. There was a possibility that the strict cleanliness required for semiconductor peripheral parts in recent years may not be satisfied.

[0013] Therefore, the present invention also aims to provide a method for producing resin particles having excellent fluidity and filling properties and containing a residue unit represented by general formula (1) without using an emulsifier and / or dispersant, and to provide resin particles having a residue unit represented by general formula (1) that do not contain an emulsifier and / or dispersant.

[0014] Furthermore, the present invention aims to provide resin particles containing a residue unit represented by general formula (1), which not only have excellent fluidity and filling properties, but also have a small amount of weight loss due to heat and do not contain an emulsifier and / or a dispersant, and a method for producing the same. [Means for solving the problem]

[0015] The present inventors have discovered that novel resin particles containing a residue unit represented by the following general formula (1) and having a volume average particle diameter of 5 μm or more and 2000 μm or less have excellent fluidity and filling properties, and have completed the present invention.

[0016] [ka]

[0017] In formula (1), Rf1, Rf2, Rf3 and Rf4 each independently represent one of the group consisting of a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, a branched perfluoroalkyl group having 3 to 7 carbon atoms, or a cyclic perfluoroalkyl group having 3 to 7 carbon atoms. The perfluoroalkyl group may have an etheric oxygen atom. Rf1, Rf2, Rf3 and Rf4 may be bonded to each other to form a ring having 4 to 8 carbon atoms, and the ring may contain an etheric oxygen atom.

[0018] Furthermore, the inventors have discovered that by using a precipitation polymerization method with a specific organic solvent, resin particles can be obtained without using an emulsifier or dispersant, and that the resin particles obtained without using an emulsifier and dispersant do not contain emulsifiers or dispersants and are resin particles that retain the inherent transparency and heat resistance of the resin, and further that no solvent remains inside the resin particles and resin particles with a small amount of weight loss on heating can be obtained, thereby arriving at a preferred embodiment of the present invention.

[0019] The present invention is as follows. [1] A resin particle comprising a residue unit represented by the following general formula (1) and having a volume average particle size of 5 μm or more and 2000 μm or less:

[0020] [ka]

[0021] (In formula (1), Rf1, Rf2, Rf3, and Rf4 each independently represent one of the group consisting of a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, a branched perfluoroalkyl group having 3 to 7 carbon atoms, or a cyclic perfluoroalkyl group having 3 to 7 carbon atoms. The perfluoroalkyl group may have an etheric oxygen atom. In addition, Rf1, Rf2, Rf3, and Rf4 may be bonded to each other to form a ring having 4 to 8 carbon atoms, and the ring may contain an etheric oxygen atom.) [2] The resin particles according to [1], wherein the volume average particle diameter is 5 μm or more and 500 μm or less. [3] The resin particles according to [1] or [2], having an angle of repose of 5° or more and 60° or less. [4] The resin particles according to any one of [1] to [3], which are a precipitation polymerization product. [5] The resin particles according to any one of [1] to [4], having a bulk density of 0.2 g / mL or more and 1.5 g / mL or less. [6] The resin particles according to any one of [1] to [5], which have a weight loss of 1% by weight or less when heated at 250° C. [7] The resin particles according to any one of [1] to [6], which do not contain an emulsifier and / or a dispersant. [8] The particle according to any one of [1] to [7], wherein the residue unit represented by general formula (1) is a perfluoro(4-methyl-2-methylene-1,3-dioxolane) residue unit represented by general formula (2).

[0022] [ka]

[0023] [9] The method includes a step of subjecting a mixture of a radical polymerization initiator, a monomer represented by the following general formula (3), and an organic solvent under polymerization conditions to obtain a resin containing a residue unit represented by general formula (4), the organic solvent is a solvent in which at least the monomer is dissolved, but at least a part of the resin produced by polymerization is not dissolved, and the resin precipitates, The method for producing resin particles according to any one of [1] to [7], wherein the resin produced by the polymerization is precipitated as particles in an organic solvent.

[0024] [ka]

[0025] (In formula (3), Rf5, Rf6, Rf6, and Rf7 each independently represent one of the group consisting of a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, a branched perfluoroalkyl group having 3 to 7 carbon atoms, or a cyclic perfluoroalkyl group having 3 to 7 carbon atoms. The perfluoroalkyl group may have an etheric oxygen atom. In addition, Rf5, Rf6, Rf6, and Rf7 may be bonded to each other to form a ring having 4 to 8 carbon atoms, and the ring may contain an etheric oxygen atom.)

[0026] [ka]

[0027] (The definitions of Rf5, Rf6, Rf6, and Rf7 in formula (4) are the same as the definitions of Rf5, Rf6, Rf6, and Rf7 in formula (3), respectively.)

[10] The method according to [9], wherein the organic solvent dissolves the monomer represented by general formula (3) but does not dissolve the resin containing the residue unit represented by general formula (4).

[11] The organic solvent contains a residue unit represented by the general formula (4) and has a weight average molecular weight Mw of 5×10 4 ~70×10 4The manufacturing method according to

[10] , wherein after the resin particles are immersed in an organic solvent having a volume 10 times (w / w) the volume of the resin particles at 50°C for 5 hours or more, the organic solvent can be confirmed to contain residual resin particles with the naked eye.

[12] The organic solvent contains a residue unit represented by the general formula (4) and has a weight average molecular weight Mw of 5×10 4 ~70×10 4 The method according to

[10] or

[11] , further comprising the steps of: immersing resin particles in an organic solvent having a 10-fold amount (w / w) of the resin particles at 50°C for 5 hours or more; cooling the solution to 25°C; and recovering a resin sample remaining in a solid state; and recovering the resin sample from the organic solvent, the weight loss rate of the resin sample being less than 20% by weight.

[13] The method according to any one of [9] to

[12] , characterized in that an organic solvent containing a fluorine atom and a hydrogen atom in the molecule is used.

[14] 14. The method according to claim 13, wherein an organic solvent having a hydrogen atom content of 1% by weight or more in the solvent molecule is used.

[15] The method according to any one of [9] to

[13] , wherein the monomer represented by general formula (3) is perfluoro(4-methyl-2-methylene-1,3-dioxolane) represented by general formula (5), and the residue unit represented by general formula (4) is a perfluoro(4-methyl-2-methylene-1,3-dioxolane) residue unit represented by general formula (6).

[0028] [ka]

[0029] [ka] Effect of the Invention

[0030] According to the present invention, it is possible to provide fluororesin particles having excellent flowability and filling properties, and a method for producing the fluororesin particles.

[0031] Furthermore, according to the present invention, it is possible to provide resin particles which not only have excellent fluidity and filling properties but also do not contain emulsifiers and dispersants, and a method for producing the same, as well as resin particles which not only have excellent fluidity and filling properties but also have a small amount of weight loss on heating, and a method for producing the same. [Brief description of the drawings]

[0032] [Figure 1] FIG. 3 is a graph showing the particle size distribution of the resin particles produced in Example 1. [Diagram 2] FIG. 3 is a graph showing the particle size distribution of the resin particles produced in Example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] The present invention will be described in detail below.

[0034] The present invention relates to resin particles containing a residue unit represented by general formula (1). The fluororesin particles of the present invention are amorphous and have high transparency and high heat resistance because they have a bulky ring structure contained in general formula (1). In addition, because they are composed only of carbon, fluorine and oxygen, they have high electrical properties, chemical resistance, waterproofness, and liquid and oil repellency.

[0035] In the present invention, Rf1, Rf2, Rf3 and Rf4 in the residue unit represented by the general formula (1) each independently represent one of the group consisting of a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, a branched perfluoroalkyl group having 3 to 7 carbon atoms, or a cyclic perfluoroalkyl group having 3 to 7 carbon atoms. The perfluoroalkyl group may have an etheric oxygen atom. Rf1, Rf2, Rf3 and Rf4 may be bonded to each other to form a ring having 4 to 8 carbon atoms, and the ring may contain an etheric oxygen atom.

[0036] Examples of linear perfluoroalkyl groups having 1 to 7 carbon atoms include a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, a nonafluorobutyl group, an undecafluoropentyl group, a tridecafluorohexyl group, and a pentadecafluoroheptyl group. Examples of branched perfluoroalkyl groups having 3 to 7 carbon atoms include a heptafluoroisopropyl group, a nonafluoroisobutyl group, a nonafluorosec-butyl group, and a nonafluorotert-butyl group. Examples of cyclic perfluoroalkyl groups having 3 to 7 carbon atoms include a heptafluorocyclopropyl group, a nonafluorocyclobutyl group, and a tridecafluorocyclohexyl group. Examples of linear perfluoroalkyl groups having 1 to 7 carbon atoms which may have an etheric oxygen atom include, for example, a -CF2OCF3 group, a -(CF2)2OCF3 group, and a -(CF2)2OCF2CF3 group. Examples of cyclic perfluoroalkyl groups having 3 to 7 carbon atoms which may have an etheric oxygen atom include a 2-(2,3,3,4,4,5,5,6,6-decafluoro)-pyrinyl group, a 4-(2,3,3,4,4,5,5,6,6-decafluoro)-pyrinyl group, and a 2-(2,3,3,4,4,5,5-heptafluoro)-furanyl group.

[0037] In order to obtain excellent heat resistance, it is preferable that at least one of Rf1, Rf2, Rf3 and Rf4 is one selected from the group consisting of a linear perfluoroalkyl group having 1 to 7 carbon atoms, a branched perfluoroalkyl group having 3 to 7 carbon atoms, and a cyclic perfluoroalkyl group having 3 to 7 carbon atoms.

[0038] Examples of the residue unit represented by general formula (1) include the following residue units.

[0039] [ka]

[0040] Among these, resin particles containing the following residue units are preferred because they have excellent heat resistance and moldability, and resins containing perfluoro(4-methyl-2-methylene-1,3-dioxolane) residue units represented by general formula (2) are more preferred.

[0041] [ka]

[0042] The resin particles of the present invention have a volume average particle diameter of 5 μm or more and 2000 μm or less, so that they have high fluidity and can be continuously supplied to a molding machine or the like. The volume average particle diameter is preferably 5 μm or more and 1000 μm or less. Furthermore, by having the volume average particle diameter in the above range, the solvent remaining in the resin particles can be suppressed, so that the amount of weight loss due to heating is small. The solvent remaining in the resin particles can also be obtained by obtaining the resin particles by a precipitation polymerization method, which will be described later.

[0043] The resin particles of the present invention preferably have a volume average particle diameter of 5 μm or more and 500 μm or less. When the volume average particle diameter is in this range, the resin particles have a higher fluidity, can be easily continuously supplied to a molding machine, and have a smaller weight loss due to heating. Furthermore, the resin particles have a higher packing property than the resin obtained by the method described in Non-Patent Document 1, and can be efficiently stored in a container. When the volume average particle diameter is 5 μm or more, the resin particles are less likely to be scattered by air currents, and the handleability of the resin particles of the present invention is improved. In addition, when the volume average particle diameter is 500 μm or less, the resin particles can be melted in a shorter time, and the efficiency of molding is improved, which is preferable.

[0044] The resin particles of the present invention preferably have a 90% particle size of 2500 μm or less, more preferably 2000 μm or less, and even more preferably 1000 μm or less, which reduces the content of coarse particles in the resin particles of the present invention and further improves flowability and moldability.

[0045] In addition, the resin particles of the present invention preferably have a 10% particle size of 3 μm or more, which reduces the content of fine particles in the resin particles of the present invention, thereby preventing dusting and improving flowability.

[0046] The volume average particle size, 90% particle size, 10% particle size and particle size distribution of the resin particles of the present invention can be evaluated by particle size distribution measurement (volume distribution) by laser diffraction scattering method. The particle size distribution by laser diffraction scattering method can be quantified with good reproducibility by dispersing the resin particles in water or an organic solvent such as methanol, and measuring after subjecting the particles to a homogenized dispersion state treatment using an ultrasonic homogenizer as necessary. An example of a laser scattering meter is Microtrack manufactured by Microtrack Bell Co., Ltd.

[0047] Volume average particle size, also known as Mean Volume Diameter, is the average particle size expressed on a volume basis. When the particle size distribution is divided into each particle size channel, the representative particle size value of each particle size channel is d, and the volume-based percentage of each particle size channel is v, it is expressed as Σ(vd) / Σ(v).

[0048] The 10% particle size refers to the particle size at which the cumulative amount is 10% when the total volume of the powder group is taken as 100%. The 90% particle size refers to the particle size at which the cumulative amount is 90% when the total volume of the powder group is taken as 100%.

[0049] The resin particles of the present invention preferably do not contain an emulsifier and / or a dispersant. By not containing an emulsifier and / or a dispersant, the resin and resin particles have excellent transparency and heat resistance. The resin particles not containing an emulsifier and / or a dispersant can be produced by using a precipitation polymerization method described later. Therefore, the resin particles of the present invention are preferably precipitation polymers. Here, the dispersant is an agent that has the function of dispersing the resin particles in a solvent, and examples thereof include polyvinyl alcohol, methyl cellulose, hydroxypropyl methyl cellulose, and hydroxyethyl methyl cellulose. The emulsifier is an agent that has the function of emulsifying the resin particles in a solvent, and examples thereof include fluorine-containing surfactants such as sodium perfluorooctanoate, sodium perfluorooctane sulfonate, and ammonium perfluorooctanoate; non-fluorine-containing surfactants such as sodium lauryl sulfate and ethylene glycol-based polymers.

[0050] The bulk density of the resin particles of the present invention is 0.2 g / cm from the viewpoint of packing property. 3 More than 1.5g / cm 3 The bulk density can be measured by the method described in the examples below.

[0051] The resin particles of the present invention may contain other monomer residue units, and examples of the other monomer residue units include tetrafluoroethylene (TFE), hexafluoropropylene (HFP), chlorotrifluoroethylene (CTFE), trifluoroethylene, hexafluoroisobutylene, perfluoroalkylethylene, fluorovinyl ether, vinyl fluoride (VF), vinylidene fluoride (VDF), perfluoro-2,2-dimethyl-1,3-dioxole (PDD), perfluoro(allyl vinyl ether), and perfluoro(butenyl vinyl ether).

[0052] The resin particles of the present invention preferably have an angle of repose of 5° or more and 60° or less. This increases the fluidity of the resin particles, making it easier to continuously supply them to a molding machine, etc. The angle of repose is more preferably 5° or more and 40° or less, and even more preferably 10° or more and 40° or less.

[0053] Here, the angle of repose refers to the angle between a plane and the ridge of the powder when the resin powder is piled up on a plane. The angle of repose can be evaluated by filling a container with resin powder, allowing it to fall naturally, and measuring the angle formed by the pile of resin powder when it is piled up on a horizontal surface. A specific method for measuring the angle of repose will be described in the examples below.

[0054] In the present invention, the molecular weight of the resin particles is not limited, and examples thereof include a weight average molecular weight of 2,500 to 2,000,000 as measured by gel permeation chromatography (GPC). From the viewpoints of the melt viscosity and mechanical strength of the resin, the weight average molecular weight is preferably 10,000 to 1,000,000 (g / mol). During the measurement, polymethylmethacrylate is used as a standard sample, and the weight average molecular weight in terms of polymethylmethacrylate is calculated from the elution times of the resin particles and the standard sample.

[0055] Next, the method for producing the resin particles of the present invention will be described.

[0056] The resin particles of the present invention can be produced, for example, by a method including a step of subjecting a mixture of a radical polymerization initiator, a monomer represented by the following general formula (3), and an organic solvent under polymerization conditions to obtain a resin containing a residue unit represented by general formula (3).

[0057] [ka]

[0058] In formula (3), Rf5, Rf6, Rf7 and Rf8 have the same meanings as Rf1, Rf2, Rf3 and Rf4 in formula (1), respectively.

[0059] [ka]

[0060] In formula (4), Rf5, Rf6, Rf7, and Rf8 have the same meanings as Rf1, Rf2, Rf3, and Rf4 in formula (1), respectively.

[0061] In the method for producing resin particles of the present invention, the organic solvent dissolves at least the monomer represented by general formula (3), but does not dissolve at least a part of the resin containing the residue unit represented by general formula (4) produced by polymerization, and causes precipitation of the resin, and the resin produced by the polymerization precipitates in the organic solvent as particles. The organic solvent used in the method for producing resin particles of the present invention may be referred to as a "precipitation polymerization solvent". More specifically, the precipitation polymerization solvent can be an organic solvent that dissolves the monomer represented by general formula (3) and does not dissolve the resin containing the residue unit represented by general formula (4), and this precipitation polymerization solvent is hereinafter referred to as precipitation polymerization solvent A. In the present invention, by using the precipitation polymerization solvent, the resin produced by the polymerization reaction can be precipitated as particles having a specific volume average particle size, and as a result, resin particles with excellent moldability and filling properties can be produced. In addition, since no polymerization aids such as emulsifiers and dispersants are used, resin particles that do not contain emulsifiers and dispersants that cause deterioration of transparency and heat resistance can be produced.

[0062] Here, the precipitation polymerization solvent A means a solvent in which the resin particles containing the residue unit represented by the general formula (4) remain after the resin particles are immersed in the organic solvent for a long period of time. Specifically, the weight average molecular weight Mw of the resin particles containing the residue unit represented by the general formula (4) is 5×10 4 ~70×10 4When the resin particles are immersed in an organic solvent having a 10-fold amount (w / w) of the resin particles at 50° C. for 5 hours or more and the remaining resin particles can be confirmed with the naked eye in the organic solvent, the organic solvent can be regarded as the precipitation polymerization solvent A. The precipitation polymerization solvent A is preferably an organic solvent in which the weight loss rate of the resin sample remaining in a solid state is less than 20% by weight when the solution is cooled to 25° C. after immersion for 5 hours or more at 50° C. The weight loss rate of the resin sample is more preferably less than 12% by weight, and even more preferably less than 10% by weight.

[0063] The resin weight loss rate can be measured by the following method. After filtering the cooled solution, the solid on the filter is rinsed with the solvent, washed multiple times with acetone, and then dried to recover the resin sample on the filter. The weight of the recovered resin is measured, and the resin weight is subtracted from the amount of resin immersed in the organic solvent, and the result is divided by the amount of resin immersed in the organic solvent to obtain the resin weight loss rate.

[0064] Examples of the precipitation polymerization solvent include non-halogen organic solvents such as acetone, methyl ethyl ketone, hexane, and butyl acetate, chlorine-containing organic solvents such as dichloromethane and chloroform, and organic solvents containing a fluorine atom in the molecule.

[0065] Furthermore, as the precipitation polymerization solvent, an organic solvent containing fluorine atoms and hydrogen atoms in the molecule is preferable because it is difficult for chain transfer reactions to occur in radical polymerization, has excellent polymerization yield, and is easy to obtain a high molecular weight substance.Specific examples of the precipitation polymerization solvent containing fluorine atoms and hydrogen atoms in the molecule include 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 2,2,2-trifluoroethanol, 1,1,1,3,3,3-hexafluoroisopropanol, 1,2,2,3,3,4,4-heptafluorocyclopentane, 1H,1H-pentafluoropropanol, 1H,1H-heptafluorobutanol, 2-perfluorobutylethanol, 4,4,4-trifluorobutanol, 1H,1H,3H-tetrafluoropropanol, 1H,1H,5H-octafluoropropanol, 1H,1H,7H-dodecafluoroheptanol, 1H,1H,3H-hexafluorobutanol, 2 , 2,3,3,3-pentafluoropropyl difluoromethyl ether, 2,2,3,3,3-pentafluoropropyl-1,1,2,2-tetrafluoroethyl ether, 1,1,2,2-tetrafluoroethyl ethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, hexafluoroisopropyl methyl ether, 1,1,3,3,3-pentafluoro-2-trifluoromethylpropyl methyl ether, 1,1,2,3,3,3-hexafluoropropyl methyl ether, 1,1,2,3,3,3-hexafluoropropyl ethyl ether, 2,2,3,4,4,4-hexafluorobutyl difluoromethyl ether, and the like.

[0066] Among them, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 2,2,2-trifluoroethanol, 1,1,1,3,3,3-hexafluoroisopropanol, and 1,2,2,3,3,4,4-heptafluorocyclopentane are preferred, and 1,2,2,3,3,4,4-heptafluorocyclopentane is preferred because it is excellent in polymerization yield and easy to obtain a high molecular weight substance. The ratio of fluorine atoms and hydrogen atoms in the molecule of the precipitation polymerization solvent is preferably fluorine atoms:hydrogen atoms=1:9 to 9:1 in terms of the number of atoms, more preferably 1:9 to 7:3, and even more preferably 4:6 to 7:3, in terms of the number of atoms, in terms of the polymerization yield, and the precipitation polymerization solvent contains fluorine atoms and hydrogen atoms in the molecule, and the content of hydrogen atoms in the solvent is preferably 1% by weight or more, more preferably 1.5% by weight or more, in terms of the weight of the solvent molecule, in terms of the polymerization yield. In addition, the concentration is preferably 1% by weight or more and 5% by weight or less, more preferably 1.5% by weight or more and 4% by weight or less, in order to provide a high polymerization yield and to easily obtain a high molecular weight substance. In addition, the precipitation polymerization solvent is preferably one that does not contain a chlorine atom in the molecule, in order to provide a high polymerization yield and to easily obtain a high molecular weight substance.

[0067] The ratio of the monomer represented by the general formula (3) to the precipitation polymerization solvent is preferably monomer:precipitation polymerization solvent=1:99 to 50:50 by weight, more preferably 5:95 to 40:60, and even more preferably 5:95 to 30:70, in order to obtain particles having excellent productivity and flow properties.

[0068] Examples of radical polymerization initiators for carrying out radical polymerization include organic peroxides such as benzoyl peroxide, lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-tetr-butyl peroxide, tetr-butylcumyl peroxide, dicumyl peroxide, tetr-butyl peroxyacetate, perfluoro(di-tetr-butyl peroxide), bis(2,3,4,5,6-pentafluorobenzoyl)peroxide, tetr-butyl peroxybenzoate, and tetr-butyl perpivalate; and azo initiators such as 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-butyronitrile), 2,2'-azobisisobutyronitrile, dimethyl-2,2'-azobisisobutyrate, and 1,1'-azobis(cyclohexane-1-carbonitrile).

[0069] In the production method of the present invention, it is preferable that the monomer represented by general formula (3) is perfluoro(4-methyl-2-methylene-1,3-dioxolane) represented by general formula (5), and the residue unit represented by general formula (4) is a perfluoro(4-methyl-2-methylene-1,3-dioxolane) residue unit represented by general formula (6).

[0070] [ka]

[0071] [ka]

[0072] Since the resin particles of the present invention are resin particles that are difficult to foam during molding, the weight loss amount when heated at 250°C is preferably 1% by weight or less, and preferably 0.5% by weight or less. In addition, the minimum weight loss amount when heated at 250°C is not particularly limited, but can be, for example, 0.001% by weight or more. In addition, since the resin particles of the present invention are resin particles that are difficult to foam during molding, the amount of residual solvent contained in the resin is preferably 1% by weight or less, and preferably 0.5% by weight or less. Here, the weight loss amount when heated at 250°C refers to the weight loss amount at 250°C when the temperature is increased from 40°C at 10°C / min under an air flow using TG-DTA, and is calculated by (1-(sample weight at 250°C) / (weighed sample weight))×100). EXAMPLES

[0073] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. <Volume average particle size> The volume average particle size (unit: μm) was measured using MT3000 manufactured by Microtrac and methanol as a dispersion medium. <10% particle size> The 10% particle size (unit: μm) was measured using MT3000 manufactured by Microtrac and methanol as the dispersion medium. <90% particle size> The 90% particle size (unit: μm) was measured using MT3000 manufactured by Microtrac and methanol as the dispersion medium. <Liquidity> The resin was rated as good (◯) when it was particulate, and as poor (×) when it was not particulate. <Bulk density> The resin particles were dropped and filled up to the 50 mL mark in the graduated cylinder without impacting the graduated cylinder. The weight (g) of the resin particles per 50 mL of this volume was measured. The weight of the resin particles was divided by the volume to calculate the bulk density (g / mL). <Fillability> Bulk densities of 0.2 g / mL or more were rated as good (◯), and those less than 0.2 g / mL were rated as poor (×). <Weight average molecular weight Mw> Measurements were performed using gel permeation chromatography equipped with a column TSKgel SuperHZM-M manufactured by Tosoh Corporation and an RI detector. The eluent used was Asahiklin AK-225 (manufactured by Asahi Glass Co., Ltd.) to which 10 wt% of 1,1,1,3,3,3-hexafluoro-2-propanol (manufactured by Wako Pure Chemical Industries, Ltd.) was added. Standard polymethylmethacrylate manufactured by Agilent was used as the standard sample, and the weight average molecular weight Mw calculated in terms of polymethylmethacrylate was calculated from the elution times of the sample and the standard sample. <250℃ heating weight loss> Approximately 10 to 15 mg of the sample was weighed into an aluminum sample pan (SSC000E030, Hitachi High-Tech Science Corporation), and the temperature was raised from 40°C to 300°C at 10°C / min under instrument air flow (160 mL / min) in a TG / DTA device (TG / DTA6200AST2, Hitachi High-Tech Science Corporation). The weight loss at 250°C was calculated as (1-(sample weight at 250°C) / (weighed sample weight)) x 100), which was defined as the weight loss upon heating to 250°C. <Angle of repose> A sample bottle was filled with 7 ml of resin powder, and a glass powder funnel (manufactured by AS ONE Corporation, funnel upper aperture 50 mm, funnel lower aperture 10 mm, funnel total length 100 mm, funnel foot height 40 mm) was fixed on top of a 4 cm diameter circular stand (made of glass) so that the bottom end of the powder funnel was 4 cm above the circular stand. Using the funnel, the resin powder was dropped from the height of the top end of the funnel, and the angle (°) of the slope of the mountain formed when it was piled up was measured with a protractor (for the comparative example, the resin powder was dropped without using a powder funnel because the fluidity of the resin powder was poor). Example 1: Preparation of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles The inside of a 1L SUS316 autoclave equipped with an anchor-type stirring blade, a nitrogen inlet tube, and a thermometer was replaced with nitrogen. 1.288g (0.00305 mol) of bis(2,3,4,5,6-pentafluorobenzoyl) peroxide was added as an initiator, 150.0g (0.615 mol) of perfluoro(4-methyl-2-methylene-1,3-dioxolane) was added as a monomer, and 1340g of Asahiklin AE-3000 (manufactured by Asahi Glass Co., Ltd., 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, content of hydrogen atoms in the solvent molecule: 1.51% by weight, fluorine atoms: hydrogen atoms in the solvent molecule = 7:3 (number ratio)) was added as a precipitation polymerization solvent, and the mixture was kept at 55°C for 24 hours under stirring to carry out precipitation polymerization. After cooling to room temperature, the liquid containing the purified resin particles was filtered, washed with acetone, and vacuum dried to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (Resin A) (yield: 56%). The shape, volume average particle size, 10% particle size, 90% particle size, bulk density, and angle of repose of the obtained resin particles are shown in Table 1. The obtained resin particles had excellent fluidity and filling properties. The weight average molecular weight Mw of the obtained Resin A was 4.4×10 5 It was.

[0074] [Table 1]

[0075] [Table 2]

[0076] Comparative Example 1: Production of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin In a 75mL glass ampoule, 0.017g (0.0000407 mol) of bis(2,3,4,5,6-pentafluorobenzoyl) peroxide was added as an initiator, 5.0g (0.0205 mol) of perfluoro(4-methyl-2-methylene-1,3-dioxolane) was added as a monomer, and 8.2g of hexafluorobenzene (content of hydrogen atoms in the solvent molecule: 0% by weight, fluorine atoms: hydrogen atoms = 10:0 (number ratio) in the solvent molecule) was added as a polymerization solvent. After repeated nitrogen replacement and depressurization, the ampoule was sealed under reduced pressure. The ampoule was placed in a thermostatic bath at 55°C and held for 24 hours to carry out radical solution polymerization, resulting in a viscous liquid in which the resin was dissolved. After cooling to room temperature, the ampoule was opened, and the resin solution was diluted with 36g of hexafluorobenzene to adjust the viscosity, to prepare a diluted resin solution. 1 L of chloroform was added to a beaker equipped with an anchor blade, and the resin dilution solution was added to the chloroform under stirring to precipitate the resin. The resin was then vacuum dried to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin (resin D) (yield: 61%). The weight average molecular weight Mw of the obtained resin D was 3.5×10 5 The shape, bulk density, and angle of repose of the obtained resin are shown in Table 1. Since the resin was amorphous, the volume average particle size could not be measured. In the case of the resin obtained, there were problems with the flowability and filling property.

[0077] (Example 2) Preparation of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles The inside of a 1L SUS316 autoclave equipped with an anchor-type stirring blade, a nitrogen inlet tube, and a thermometer was replaced with nitrogen. 0.346 g (0.000820 mol) of bis(2,3,4,5,6-pentafluorobenzoyl) peroxide was added as an initiator, 100.0 g (0.410 mol) of perfluoro(4-methyl-2-methylene-1,3-dioxolane) was added as a monomer, and 890 g of 2,2,2-trifluoroethanol (content of hydrogen atoms in the solvent molecule: 3.03 wt%, fluorine atoms: hydrogen atoms = 5:5 (number ratio) in the solvent molecule) was added as a precipitation polymerization solvent, and the mixture was kept at 55°C for 24 hours with stirring. Precipitation polymerization was carried out by cooling to room temperature, filtering the liquid containing the purified resin particles, washing with acetone, and drying in a vacuum to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (resin B) (yield: 78%). The shape, volume average particle size, 10% particle size, 90% particle size, bulk density, and angle of repose of the obtained resin particles are shown in Table 1. The obtained resin particles had excellent fluidity and filling properties. The weight average molecular weight Mw of the obtained resin B was 1.1 x 10 5 It was.

[0078] (Example 3) Preparation of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles The inside of a 1L SUS316 autoclave equipped with an anchor-type stirring blade, a nitrogen inlet tube and a thermometer was replaced with nitrogen. 0.519g (0.00123 mol) of bis(2,3,4,5,6-pentafluorobenzoyl) peroxide as an initiator, 150.0g (0.615 mol) of perfluoro(4-methyl-2-methylene-1,3-dioxolane) as a monomer, and 1150g of chloroform as a precipitation polymerization solvent were added, and precipitation polymerization was carried out by holding at 55°C for 24 hours under stirring. After cooling to room temperature, the liquid containing the purified resin particles was filtered, washed with acetone, and vacuum dried to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (resin C) (yield: 19%). The shape, volume average particle size, 10% particle size, 90% particle size, bulk density, and angle of repose of the obtained resin particles are shown in Table 1. The resulting resin particles had excellent fluidity and filling properties. The weight average molecular weight Mw of the resulting resin C was 7.0×103 It was.

[0079] (Example 4) Preparation of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles The inside of a 1L SUS316 autoclave equipped with an anchor-type stirring blade, a nitrogen inlet tube, and a thermometer was replaced with nitrogen. 1.038g (0.00246 mol) of bis(2,3,4,5,6-pentafluorobenzoyl) peroxide was added as an initiator, 300.0g (1.23 mol) of perfluoro(4-methyl-2-methylene-1,3-dioxolane) was added as a monomer, and 1200g of Zeorola-H (manufactured by Zeon Corporation, 1,2,2,3,3,4,4-heptafluorocyclopentane, content of hydrogen atoms in the solvent molecule: 1.55% by weight, fluorine atoms: hydrogen atoms in the solvent molecule = 7:3 (number ratio)) was added as a precipitation polymerization solvent, and the mixture was kept at 55°C for 24 hours under stirring to carry out precipitation polymerization. After cooling to room temperature, the liquid containing the purified resin particles was filtered, washed with acetone, and vacuum dried to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (Resin E) (yield: 86%). The shape, volume average particle size, 10% particle size, 90% particle size, bulk density, and angle of repose of the obtained resin particles are shown in Table 2. The obtained resin particles had excellent fluidity and filling properties. The weight average molecular weight Mw of the obtained Resin E was 4.9×10 5 It was.

[0080] (Example 5) Preparation of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles The inside of a 1L SUS316 autoclave equipped with an anchor-type stirring blade, a nitrogen inlet tube, and a thermometer was replaced with nitrogen. 0.519g (0.00123 mol) of bis(2,3,4,5,6-pentafluorobenzoyl) peroxide was added as an initiator, 150.0g (0.615 mol) of perfluoro(4-methyl-2-methylene-1,3-dioxolane) was added as a monomer, and 1340g of 1,1,1,3,3,3-hexafluoroisopropanol (content of hydrogen atoms in the solvent molecule: 1.82% by weight, fluorine atoms: hydrogen atoms = 6:4 (number ratio) in the solvent molecule) was added as a precipitation polymerization solvent, and the mixture was kept at 55°C for 24 hours under stirring to carry out precipitation polymerization. After cooling to room temperature, the liquid containing the purified resin particles was filtered, washed with acetone, and vacuum dried to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (Resin F) (yield: 59%). The shape, volume average particle size, 10% particle size, 90% particle size, bulk density, and angle of repose of the obtained resin particles are shown in Table 2. The obtained resin particles had excellent fluidity and filling properties. The weight average molecular weight Mw of the obtained Resin F was 7.9×10 5 It was.

[0081] (Reference example 1) The resin particles obtained in Example 1 were immersed in 10 times the amount of each of the solvents at 50° C. for 5 hours, and the presence or absence of remaining resin particles was observed with the naked eye.

[0082] The organic solvents in which residual resin particles were confirmed with the naked eye are as follows: 1,1,2,2-Tetrafluoroethyl-2,2,2-trifluoroethyl ether, 2,2,2-trifluoroethanol, 1,1,1,3,3,3-hexafluoroisopropanol, 1,2,2,3,3,4,4-heptafluorocyclopentane, chloroform.

[0083] After that, it was cooled to 25°C, filtered, and rinsed with the solvent to extract the resin particles, which were then washed twice with 10 times the amount of acetone and vacuum dried. The recovery rate was calculated from the dry weight, and in both cases the recovery rate was 90% or more. The filtrate obtained above was distilled off, and the solid content in the filtrate was calculated, and the solid content in the filtrate was less than 10% relative to the resin particles used. From the above results, it was confirmed that the weight loss rate of the resin weight was less than 10% by weight. (Reference example 2) The resin particles obtained in Example 1 were immersed in 10 times the amount of each of the following solvents at 50° C. for 5 hours, and the presence or absence of remaining resin particles was observed with the naked eye.

[0084] The organic solvents in which no resin particles remained visible to the naked eye were as follows: Hexafluorobenzene, CF3CF2CHCl2 (hydrogen atom content in solvent molecule: 0.55% by weight, fluorine atoms:hydrogen atoms in solvent molecule = 8:2 (number ratio)) As a result of visual observation at 50°C, all the solutions were transparent, with almost no turbidity. After that, they were cooled to 25°C, filtered, rinsed with the solvent, and the filter was vacuum dried. The recovery rate was calculated from the weight increase of the filter, and all were less than 5% by weight. From the above results, it was confirmed that the weight loss rate of the resin after immersion in the solvent was 95% by weight or more. [Industrial Applicability]

[0085] The present invention provides fluororesin particles which have excellent flowability and filling properties and a small amount of weight loss on heating, and a method for producing the fluororesin particles.

Claims

[Claim 1] A resin particle comprising a residue unit represented by the following general formula (1) and having a volume average particle size of 5 μm or more and 2000 μm or less: 【Chemistry 1】 (In formula (1), Rf １ , Rf ２ , Rf ３ , Rf ４ each independently represents one member of the group consisting of a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, a branched perfluoroalkyl group having 3 to 7 carbon atoms, or a cyclic perfluoroalkyl group having 3 to 7 carbon atoms. The perfluoroalkyl group may have an etheric oxygen atom. １ , Rf ２ , Rf ３ , Rf ４ may be linked together to form a ring having 4 to 8 carbon atoms, and the ring may contain an ether oxygen atom.

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