Fluororesin particles and method for producing the same

Abstract

To provide a fluororesin particle excellent in fluidity and fillability and a method for producing the fluororesin particles.SOLUTION: A resin particle is provided, 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. In formula (1), Rf1,Rf2,Rf3, and Rf4 each independently represent a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, or a branched perfluoroalkyl group having 3 to 7 carbon atoms, or a cyclic perfluoroalkyl groups having 3 to 7 carbon atoms. The perfluoroalkyl group may have an ether oxygen atom. Furthermore, Rf1,Rf2,Rf3, and Rf4 may be linked to each other to form a ring having 4 to 8 carbon atoms, and the ring may contain an etheric oxygen atom.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Fluorine-based resins are used in protective films for electronic components such as semiconductors, water-repellent films for inkjet printer heads, and water- and oil-repellent coatings for filters due to their excellent electrical properties, chemical resistance, water resistance, and hydrophilic properties.

[0003] In particular, fluororesins containing oxolane rings have a bulky ring structure, resulting in an amorphous state with high transparency and high heat resistance. Furthermore, being composed solely of carbon, fluorine, and oxygen, they possess high electrical properties, chemical resistance, water resistance, and liquid and oil repellency. Moreover, their amorphous nature allows for melt molding.

[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 a glass sealed tube in the presence of nitrogen fluoride (N2F2). In this example, no solvent was used, and the specific form of the obtained polymer is not described. Non-Patent Document 1 describes obtaining a polymer of PFMMD as a fluororesin containing an oxolane ring by bulk polymerization or solution polymerization. In this specification, unless otherwise specified, resin and polymer are used synonymously. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] U.S. Patent No. 3308107 [Non-patent literature]

[0006] [Non-Patent Document 1] Macromolecules 2005, 38, 4237 [Overview of the project] [Problems that the invention aims to solve]

[0007] Non-patent document 1 states 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 precipitate the resin. There is no description of the specific form of the resin after purification of bulk polymerization or the resin obtained by precipitation with the addition of chloroform.

[0008] As a result of the inventors' investigations, the resins obtained by the methods described in Patent Document 1 and Non-Patent Document 1 had an amorphous, non-particulate form. Therefore, there were problems with the fluidity of the resin. For example, it was found that handling problems arose, such as difficulty in continuously supplying the resin into the molding machine when melt molding the resin. Furthermore, it was found that because the resins described in Patent Document 1 and Non-Patent Document 1 have the above-mentioned form, when filling the molding machine with the resin, for example, it was not possible to fill a predetermined volume with the desired weight of resin, i.e., the fillability was low. This also led to the problem of low economic efficiency when transporting the goods, as a container with a large volume relative to the weight of the resin was required.

[0009] Therefore, the present invention aims to provide resin particles containing residue units represented by general formula (1) that have excellent fluidity and packing properties, and a method for producing the same, in order to solve the above problems.

[0010] Furthermore, as a result of further investigation by the present inventors, the resins produced by the methods described in Patent Document 1 and Non-Patent Documents have an amorphous, non-particulate form, making it difficult to remove the solvent incorporated into the resin. If solvent remains in the resin, the weight loss during heating is significant, leading to problems such as foaming during molding and deterioration of the working environment during molding.

[0011] Therefore, the present invention also aims to provide resin particles containing residue units represented by general formula (1) that not only have excellent fluidity and filling properties but also exhibit small weight loss when heated, as well as a method for producing the same.

[0012] In addition, in the manufacture of fluororesins, resin particles can generally be obtained by means such as emulsion polymerization and suspension polymerization. However, in these methods, emulsifiers or dispersants are used as polymerization aids. However, the emulsifiers or dispersants used can remain inside the resin particles, becoming foreign matter, and can also cause discoloration when the resin is heated, potentially impairing transparency and heat resistance. This meant that the stringent cleanliness requirements for semiconductor peripheral components in recent years could not be met.

[0013] Therefore, the present invention also aims to provide a method for producing resin particles containing residue units represented by general formula (1) that have excellent fluidity and packing properties without using emulsifiers and / or dispersants, and to provide resin particles containing residue units represented by general formula (1) that do not contain emulsifiers and / or dispersants.

[0014] Furthermore, the present invention aims to provide resin particles containing residue units represented by general formula (1) that not only have excellent fluidity and filling properties but also exhibit low thermal weight loss and do not contain emulsifiers and / or dispersants, as well as a method for producing the same. [Means for solving the problem]

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

[0016] [Chemical Formula]

[0017] In formula (1), Rf1, Rf2, Rf3 and Rf4 each independently represent one kind of 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. Further, Rf1, Rf2, Rf3 and Rf4 may be linked to each other to form a ring having 4 to 8 carbon atoms, and the ring may be a ring containing an etheric oxygen atom.

[0018] Furthermore, the inventors of the present invention have found that by using a precipitation polymerization method using a specific organic solvent, resin particles can be obtained without using an emulsifier or a dispersant, and the resin particles obtained without using an emulsifier and a dispersant do not contain an emulsifier and a dispersant and retain the original transparency and heat resistance of the resin. Furthermore, it has been found that resin particles with a small amount of weight loss on heating can be obtained without residual solvent inside the resin particles, leading to a preferred embodiment of the present invention.

[0019] The present invention is as follows. [1] Resin particles containing residue units represented by the following general formula (1) and having a volume average particle diameter of 5 μm or more and 2000 μm or less. [Chemical Formula] (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. Furthermore, Rf1, Rf2, Rf3, and Rf4 may be linked to each other to form a ring having 4 to 8 carbon atoms, and this 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] Resin particles as described in [1] or [2], wherein the angle of repose is 5° or more and 60° or less. [4] The resin particles are a precipitated polymer, as described in any one of [1] to [3]. [5] Resin particles according to any one of items [1] to [4], having a bulk density of 0.2 g / mL or more and 1.5 g / mL or less. [6] Resin particles according to any one of [1] to [5], wherein the weight loss when heated to 250°C is 1% by weight or less. [7] The resin particles are those described in any one of [1] to [6], wherein the resin particles do not contain an emulsifier and / or a dispersant. [8] The particle described in 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). [ka] [9] The process involves placing 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 residue units represented by the general formula (4). The organic solvent is a solvent in which at least the monomer dissolves, and at least a portion of the resin produced by polymerization does not dissolve, causing a precipitate of the resin. The resin produced by the polymerization precipitates in an organic solvent as particles, a method for producing resin particles according to any one of [1] to [7]. [ka] (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. Furthermore, Rf5, Rf6, Rf6, and Rf7 may be linked to each other to form a ring having 4 to 8 carbon atoms, and this ring may contain an etheric oxygen atom.) [ka] (The definitions of Rf5, Rf6, Rf6, and Rf7 in equation (4) are the same as the definitions of Rf5, Rf6, Rf6, and Rf7 in equation (3), respectively.)

[10] The method for producing resin according to [9], wherein the organic solvent is an organic solvent that dissolves monomers represented by general formula (3) and does not dissolve resins containing residue units represented by general formula (4).

[11] The aforementioned organic solvent has a quantity-average molecular weight Mw of 5 × 10⁻¹⁰, which includes residue units represented by general formula (4). 4 ~70×10 4 The manufacturing method described in

[10] , wherein the resin particles are immersed in an organic solvent at 50°C for 5 hours or more in an amount 10 times (w / w) relative to the resin particles, and the organic solvent is such that the presence of resin particles can be visually confirmed in the organic solvent.

[12] The aforementioned organic solvent has a quantity-average molecular weight Mw of 5 × 10⁻¹⁰, which includes residue units represented by general formula (4). 4 ~70×10 4The manufacturing method according to

[10] or

[11] , wherein the resin particles are immersed in an organic solvent in an amount 10 times (w / w) relative to the resin particles at 50°C for 5 hours or more, the solution is cooled to 25°C, and the resin sample remaining in a solid state is recovered, and the organic solvent is such that the weight loss rate of the resin sample is less than 20% by weight.

[13] A method for producing a product according to any one of the claims [9] to

[12] , characterized by using an organic solvent containing a fluorine atom and a hydrogen atom in the molecule.

[14] The manufacturing method according to claim 13, characterized in that an organic solvent is used in which the hydrogen atom content in the solvent molecule is 1% by weight or more.

[15] A method for producing a product 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). [ka] [ka] [Effects of the Invention]

[0020] According to the present invention, it is possible to provide fluororesin particles with excellent fluidity and filling properties, and a method for producing fluororesin particles.

[0021] Furthermore, according to the present invention, it is possible to provide resin particles that not only have excellent fluidity and filling properties but also do not contain emulsifiers or dispersants, as well as a method for producing the same, and resin particles that not only have excellent fluidity and filling properties but also have a small weight loss when heated, as well as a method for producing the same. [Brief explanation of the drawing]

[0022] [Figure 1]This figure shows the particle size distribution of the resin particles produced in Example 1. [Figure 2] This figure shows the particle size distribution of the resin particles produced in Example 4. [Modes for carrying out the invention]

[0023] The present invention will be described in detail below.

[0024] The present invention relates to resin particles containing residue units represented by general formula (1). The fluororesin particles of the present invention have a bulky ring structure contained in general formula (1), and therefore are amorphous, highly transparent, and highly heat-resistant. Furthermore, being composed solely of carbon, fluorine, and oxygen, they possess high electrical properties, chemical resistance, water resistance, and hydrophilic and oleophilic properties.

[0025] In the present invention, the Rf1, Rf2, Rf3, and Rf4 groups in the residue unit represented by 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. Furthermore, Rf1, Rf2, Rf3, and Rf4 may be linked to each other to form a ring having 4 to 8 carbon atoms, and this ring may contain an etheric oxygen atom.

[0026] Examples of linear perfluoroalkyl groups having 1 to 7 carbon atoms include trifluoromethyl, pentafluoroethyl, heptafluoropropyl, nonafluorobutyl, undecafluoropentyl, tridecafluorohexyl, and pentadecafluoroheptyl groups. Examples of branched perfluoroalkyl groups having 3 to 7 carbon atoms include heptafluoroisopropyl, nonafluoroisobutyl, nonafluorosec-butyl, and nonafluorotert-butyl groups. Examples of cyclic perfluoroalkyl groups having 3 to 7 carbon atoms include heptafluorocyclopropyl, nonafluorocyclobutyl, and tridecafluorocyclohexyl groups. Examples of linear perfluoroalkyl groups that may have etheric oxygen atoms with 1 to 7 carbon atoms include -CF2OCF3, -(CF2)2OCF3, and -(CF2)2OCF2CF3 groups, while examples of cyclic perfluoroalkyl groups that may have etheric oxygen atoms with 3 to 7 carbon atoms include 2-(2,3,3,4,4,5,5,6,6-decafluoro)-pyrinyl group, 4-(2,3,3,4,4,5,5,6,6-decafluoro)-pyrinyl group, and 2-(2,3,3,4,4,5,5-heptafluoro)-furanyl group.

[0027] To achieve excellent heat resistance, it is preferable that at least one of Rf1, Rf2, Rf3, and Rf4 is one of 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.

[0028] Examples of residue units represented by general formula (1) include the following:

[0029] [ka]

[0030] Among these, resin particles containing the following residue units are preferred due to their excellent heat resistance and moldability, and resins containing the perfluoro(4-methyl-2-methylene-1,3-dioxolane) residue unit represented by general formula (2) are more preferred.

[0031] [ka]

[0032] The resin particles of the present invention have high fluidity due to their volume-average particle diameter of 5 μm to 2000 μm, enabling continuous supply to molding machines and the like. Preferably, the volume-average particle diameter is 5 μm to 1000 μm. Furthermore, having the volume-average particle diameter within the above range suppresses solvent residue on the resin particles, resulting in a small weight loss upon heating. Note that solvent residue on the resin particles can also be achieved by obtaining the resin particles using the precipitation polymerization method described later.

[0033] The resin particles of the present invention are more preferably 5 μm or more and 500 μm or less in volume average particle diameter. Having a volume average particle diameter within this range results in higher fluidity, easier continuous supply to molding machines and the like, and smaller weight loss during heating. Furthermore, compared to the resin obtained by the method described in Non-Patent Document 1, the packing efficiency is increased, allowing for efficient storage in containers. A volume average particle diameter of 5 μm or more makes the resin particles less susceptible to scattering by airflow, improving the handling of the resin particles of the present invention. Additionally, a volume average particle diameter of 500 μm or less is preferable because it allows the resin particles to melt in a shorter time, improving the efficiency of the molding process.

[0034] The resin particles of the present invention preferably have a 90% particle diameter of 2500 μm or less, more preferably 2000 μm or less, and more preferably 1000 μm or less. This reduces the content of coarse particles in the resin particles of the present invention, further improving fluidity and moldability.

[0035] Furthermore, it is preferable that the resin particles of the present invention have a 10% particle diameter of 3 μm or more. This reduces the content of fine particles in the resin particles of the present invention, further preventing dust formation and improving fluidity.

[0036] The volume-average particle diameter, 90% particle diameter, 10% particle diameter, and particle diameter distribution of the resin particles of the present invention can be evaluated by measuring the particle diameter distribution (volume distribution) using laser diffraction scattering. The particle diameter distribution using laser diffraction scattering can be quantified with good reproducibility by dispersing the resin particles in water or an organic solvent such as methanol, and then, if necessary, homogenizing the particle dispersion using an ultrasonic homogenizer before measurement. A Microtrac manufactured by Microtrac-Bell Corporation can be used as an example of a laser scattering meter.

[0037] The mean volume diameter, also known as the mean particle diameter, is the average particle diameter expressed on a volume basis. It is expressed as Σ(vd) / Σ(v) when the particle diameter distribution is divided into individual particle size channels, the representative particle size value of each channel is denoted as d, and the percentage of the volume basis for each particle size channel is denoted as v.

[0038] The 10% particle size refers to the particle size at which the cumulative volume of the powder aggregate reaches 10% when the total volume of the aggregate is considered 100%. The 90% particle size refers to the particle size at which the cumulative volume of the powder aggregate reaches 90% when the total volume of the aggregate is considered 100%.

[0039] The resin particles of the present invention preferably do not contain emulsifiers and / or dispersants. The absence of emulsifiers and / or dispersants results in resins and resin particles with excellent transparency and heat resistance. Resin particles that do not contain emulsifiers and / or dispersants can be produced using the precipitation polymerization method described later. Therefore, the resin particles of the present invention are preferably precipitate polymers. Here, a dispersant is an agent that disperses the resin particles in a solvent, and examples include polyvinyl alcohol, methylcellulose, hydroxypropyl methylcellulose, hydroxyethyl methylcellulose, etc. An emulsifier is an agent that emulsifies the resin particles in a solvent, and examples include fluorine-containing surfactants such as sodium perfluorooctanoate, sodium perfluorooctanesulfonate, and ammonium perfluorooctanoate salt; and non-fluorine surfactants such as sodium lauryl sulfate and ethylene glycol polymers.

[0040] The bulk density of the resin particles of the present invention is 0.2 g / cm³ from the viewpoint of packing efficiency. 3 More than 1.5g / cm 3 The following is preferable. The bulk density can be measured by the method described in the examples below.

[0041] The resin particles of the present invention may contain other monomeric residue units, such as 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).

[0042] The resin particles of the present invention preferably have an angle of repose of 5° to 60°. This increases the fluidity of the resin particles, facilitating continuous supply to molding machines and the like. The angle of repose is more preferably 5° to 40°, and even more preferably 10° to 40°.

[0043] Here, the angle of repose refers to the angle formed by the plane and the edges of the resin powder when the powder is deposited 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 deposited on a horizontal surface. The specific method for measuring the angle of repose will be described in the examples below.

[0044] In the present invention, there are no restrictions on the molecular weight of the resin particles. For example, the weight-average molecular weight measured by gel permeation chromatography (GPC) can be 2,500 to 2,000,000. From the viewpoint of the melt viscosity and mechanical strength of the resin, it is preferable that it be 10,000 to 1,000,000 (g / mol). When measuring, polymethyl methacrylate is used as a standard sample, and the weight-average molecular weight in terms of polymethyl methacrylate is calculated from the elution time of the resin particles and the standard sample.

[0045] Next, the method for producing resin particles according to the present invention will be described.

[0046] The resin particles of the present invention can be produced, for example, by a method that includes the step of placing 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 residue units represented by the general formula (3).

[0047] [ka]

[0048] In equation (3), Rf5, Rf6, Rf7, and Rf8 are equivalent to Rf1, Rf2, Rf3, and Rf4 in equation (1), respectively.

[0049] [ka]

[0050] In equation (4), Rf5, Rf6, Rf7, and Rf8 are equivalent to Rf1, Rf2, Rf3, and Rf4 in equation (1), respectively.

[0051] In the method for producing resin particles of the present invention, the organic solvent is a solvent that dissolves at least the monomer represented by general formula (3) and does not dissolve at least a portion of the resin containing the residue units represented by general formula (4) produced by polymerization, thereby causing a precipitate of the resin, and the resin produced by 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 the "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 units 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 packing properties can be produced. Furthermore, since polymerization aids such as emulsifiers and dispersants are not used, resin particles that do not contain emulsifiers and dispersants, which can impair transparency and heat resistance, can be produced.

[0052] Here, precipitation polymerization solvent A refers to the solvent in which resin particles containing residue units represented by general formula (4) remain after being immersed in the organic solvent for a long period of time. Specifically, the weight-average molecular weight Mw of the residue units containing the residue units represented by general formula (4) is 5 × 10⁻⁶. 4 ~70×10 4When resin particles are immersed in an organic solvent at 50°C for 5 hours or more in an amount 10 times (w / w) relative to the resin particles, and residual resin particles can be visually confirmed in the organic solvent, the organic solvent can be considered as precipitation polymerization solvent A. Precipitated polymerization solvent A is preferably an organic solvent in which, after immersion at 50°C for 5 hours or more and cooling the solution to 25°C, the resin sample remaining in a solid state is recovered, and the weight loss rate of the resin sample is less than 20% by weight. More preferably, the weight loss rate of the resin sample is less than 12% by weight, and even more preferably less than 10% by weight.

[0053] The rate of resin weight reduction 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, dried, and the resin sample on the filter is collected. The weight of the collected resin is measured, and the resin weight reduction rate is defined as the percentage obtained by subtracting the weight of the collected resin from the amount of resin immersed in the organic solvent and dividing the result by the amount of resin immersed in the organic solvent.

[0054] Examples of precipitation polymerization solvents include non-halogenated organic solvents such as acetone, methyl ethyl ketone, hexane, and butyl acetate, as well as chlorinated organic solvents such as dichloromethane and chloroform, and organic solvents containing fluorine atoms in their molecules.

[0055] Furthermore, as a precipitation polymerization solvent, organic solvents containing fluorine and hydrogen atoms in the molecule are preferred because they are less prone to chain transfer reactions in radical polymerization, offer excellent polymerization yield, and facilitate the acquisition of high molecular weight products. Specific precipitation polymerization solvents containing fluorine 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 Examples include 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, and 2,2,3,4,4,4-hexafluorobutyl difluoromethyl ether.

[0056] Among these, 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 exhibits excellent polymerization yield and makes it easy to obtain high molecular weight products. As for the ratio of fluorine atoms to hydrogen atoms in the molecule of the precipitate polymerization solvent, a ratio of fluorine atoms to hydrogen atoms of 1:9 to 9:1 is preferred in terms of the number of atoms, more preferably 1:9 to 7:3, and even more preferably 4:6 to 7:3, because it exhibits excellent polymerization yield.

[0057] As a precipitation polymerization solvent, it is preferable that the solvent contains both fluorine and hydrogen atoms in its molecule, as this results in excellent polymerization yield, and that the hydrogen atom content in the solvent is preferably 1% by weight or more, and more preferably 1.5% by weight or more, relative to the weight of the solvent molecule. Furthermore, as this results in excellent polymerization yield and facilitates the acquisition of high molecular weight products, it is preferable that the solvent contains 1% to 5% by weight, and more preferably 1.5% to 4% by weight. Additionally, as a precipitation polymerization solvent, it is preferable that the solvent does not contain chlorine atoms in its molecule, as this results in excellent polymerization yield and facilitates the acquisition of high molecular weight products.

[0058] The ratio of monomer represented by general formula (3) to precipitate polymerization solvent is preferably monomer:precipitated 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 with excellent productivity and flow characteristics.

[0059] Examples of radical polymerization initiators used in 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-based 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-carbonnitrile).

[0060] 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).

[0061] [ka]

[0062] [ka]

[0063] Since the resin particles of the present invention are less prone to foaming during molding, it is preferable that the weight loss when heated to 250°C is 1% by weight or less, and more preferably 0.5% by weight or less. Furthermore, there are no particular limitations on the minimum amount of weight loss when heated to 250°C, but for example, 0.001% by weight or more can be exemplified. In addition, since the resin particles of the present invention are less prone to foaming during molding, it is preferable that the amount of residual solvent contained in the resin is 1% by weight or less, and more preferably 0.5% by weight or less. Here, the weight loss when heated to 250°C refers to the weight loss at 250°C when the temperature is raised from 40°C at 10°C / min under an air flow using TG-DTA, and is calculated from (1 - (Sample weight at 250°C) / (Weighed sample weight)) × 100). [Examples]

[0064] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0065] <Volume-average particle diameter> Using a Microtrac MT3000 and methanol as the dispersion medium, the volume-average particle size (in μm) was measured.

[0066] <10% particle size> Using a Microtrac MT3000 and methanol as the dispersion medium, the 10% particle size (in μm) was measured.

[0067] <90% particle size> Using a Microtrac MT3000 and methanol as the dispersion medium, the 90% particle size (in μm) was measured.

[0068] <Liquidity> Resin was rated as good (○) if it was particulate, and as poor (×) if it was not particulate.

[0069] <Bulk density> Resin particles were dropped into a graduated cylinder without impact until the 50 mL mark was reached. The weight (g) of the resin particles per 50 mL volume was measured. The bulk density (g / mL) was calculated by dividing the weight of the resin particles by the volume.

[0070] <Fillability> A bulk density of 0.2 g / mL or higher was rated as good (○), and a bulk density of less than 0.2 g / mL was rated as poor (×).

[0071] <Weight average molecular weight Mw> Measurements were performed using gel permission chromatography with a TSKgel SuperHZM-M column manufactured by Tosoh Corporation and an RI detector. The eluent used was Asahi Clean AK-225 (manufactured by Asahi Glass Co., Ltd.) with 10 wt% 1,1,1,3,3,3-hexafluoro-2-propanol (manufactured by Wako Pure Chemical Industries, Ltd.) added to AK-225. Standard polymethyl methacrylate from Agilent was used as the standard sample, and the weight-average molecular weight (Mw) in terms of polymethyl methacrylate was calculated from the elution times of the sample and the standard sample.

[0072] <250℃ heating weight loss> Approximately 10-15 mg of sample was weighed into an aluminum sample pan (SSC000E030, manufactured by Hitachi High-Tech Science Corporation). The sample was then heated from 40°C to 300°C at a rate of 10°C / min under an instrumentation airflow (160 mL / min) using a TG / DTA instrument (TG / DTA6200AST2, manufactured by Hitachi High-Tech Science Corporation). The weight loss at 250°C was calculated as (1 - (weight of sample at 250°C) / (weight of weighed sample)) × 100) and defined as the weight loss at 250°C.

[0073] <Angle of repose> Fill a sample bottle with 7 ml of resin powder. Place a glass powder funnel (manufactured by AS ONE Corporation, upper funnel diameter 50 mm, lower funnel diameter 10 mm, total funnel length 100 mm, height of the funnel foot part 40 mm) on top of a circular base (made of glass) with a diameter of 4 cm. Fix the funnel so that the lower end of the powder funnel is 4 cm above the circular base. Using the funnel, let the resin powder fall from the height of the upper end of the funnel, and measure the angle (°) of the slope of the pile formed when it accumulates with a protractor. (For the comparative example, since the fluidity of the resin powder was poor, the resin powder was dropped without using a powder funnel.)

[0074] (Example 1) Production of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles The inside of a 1 L SUS316 autoclave equipped with an anchor-type stirring blade, a nitrogen inlet tube, and a thermometer was purged with nitrogen. 1.288 g (0.00305 mol) of bis(2,3,4,5,6-pentafluorobenzoyl) peroxide as an initiator, 150.0 g (0.615 mol) of perfluoro(4-methyl-2-methylene-1,3-dioxolane) as a monomer, and 1340 g of Asahiklin AE-3000 (manufactured by Asahi Glass, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, hydrogen atom content in the solvent molecule: 1.51 wt%, fluorine atom in the solvent molecule: hydrogen atom = 7:3 (number ratio)) 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 off, 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 diameter, 10% particle diameter, 90% particle diameter, bulk density, and angle of repose of the obtained resin particles are shown in Table 1. The obtained resin particles were excellent in fluidity and filling properties. The weight average molecular weight Mw of the obtained resin A was 4.4×10 5 It was.

[0075]

Table 1

[0076] [Table 2]

[0077] (Comparative Example 1) Production of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin In a 75 mL glass ampoule, 0.017 g (0.0000407 mol) of bis(2,3,4,5,6-pentafluorobenzoyl) peroxide was added as an initiator, 5.0 g (0.0205 mol) of perfluoro(4-methyl-2-methylene-1,3-dioxolane) as a monomer, and 8.2 g of hexafluorobenzene (hydrogen atom content in solvent molecule: 0 wt%, fluorine atom:hydrogen atom = 10:0 (number ratio)) was added as a polymerization solvent. After repeated nitrogen purging and pressure release, the ampoule was sealed under reduced pressure. Radical solution polymerization was carried out by placing this ampoule in a 55°C constant temperature bath and holding it for 24 hours, 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 36 g of hexafluorobenzene to adjust the viscosity and prepare a diluted resin solution. In a beaker equipped with anchor blades, 1 L of chloroform was added, and under stirring, the aforementioned diluted resin solution was added to the chloroform to precipitate the resin. Perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin (resin D) was obtained by vacuum drying (yield: 61%). The weight-average molecular weight Mw of the obtained resin D was 3.5 × 10⁶. 5 The shape, bulk density, and angle of repose of the obtained resin are shown in Table 1. Because the resin was amorphous, the volume-average particle size could not be measured. In this case, the obtained resin had issues with fluidity and packing properties.

[0078] (Example 2) Production of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles The inside of a 1 L SUS316 autoclave equipped with an anchor-type stirring blade, a nitrogen inlet tube, and a thermometer was purged 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) as a monomer, and 890 g of 2,2,2-trifluoroethanol (hydrogen atom content in solvent molecules: 3.03 wt%, fluorine atom:hydrogen atom ratio in solvent molecules = 5:5 (number ratio)) was added as a precipitation polymerization solvent, and the mixture was held at 55°C for 24 hours under stirring. Precipitation polymerization was carried out. 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 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 exhibited excellent fluidity and packing properties. The weight-average molecular weight Mw of the obtained resin B was 1.1 × 10⁻⁶. 5 That was the case.

[0079] (Example 3) Production of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles The inside of a 1 L SUS316 autoclave equipped with an anchor-type stirring blade, a nitrogen inlet tube, and a thermometer was purged with nitrogen. 0.519 g (0.00123 mol) of bis(2,3,4,5,6-pentafluorobenzoyl) peroxide was added as an initiator, 150.0 g (0.615 mol) of perfluoro(4-methyl-2-methylene-1,3-dioxolane) as a monomer, and 1150 g of chloroform as a precipitation polymerization solvent were added. Precipitation polymerization was carried out by holding the mixture at 55°C for 24 hours under stirring. After cooling to room temperature, the liquid containing the purified resin particles was filtered off, 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 diameter, 10% particle diameter, 90% particle diameter, bulk density, and angle of repose of the obtained resin particles are shown in Table 1. The obtained resin particles exhibited excellent fluidity and packing properties. The weight-average molecular weight Mw of the obtained resin C was 7.0 × 10⁻⁶.3 That was the case.

[0080] (Example 4) Production of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles The inside of a 1 L SUS316 autoclave equipped with an anchor-type stirring blade, a nitrogen inlet tube, and a thermometer was purged with nitrogen. 1.038 g (0.00246 mol) of bis(2,3,4,5,6-pentafluorobenzoyl) peroxide was added as an initiator, 300.0 g (1.23 mol) of perfluoro(4-methyl-2-methylene-1,3-dioxolane) as a monomer, and 1200 g of Zeolora-H (manufactured by Nippon Zeon, 1,2,2,3,3,4,4-heptafluorocyclopentane, hydrogen atom content in solvent molecules: 1.55 wt%, fluorine atoms:hydrogen atoms in solvent molecules = 7:3 (number ratio)) was added as a precipitation polymerization solvent. Precipitation polymerization was carried out by holding the mixture at 55°C for 24 hours under stirring. The liquid containing the purified resin particles was cooled to room temperature, filtered, washed with acetone, and vacuum-dried to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (resin E) (yield: 86%). Table 2 shows the shape, volume-average particle size, 10% particle size, 90% particle size, bulk density, and angle of repose of the obtained resin particles. The obtained resin particles exhibited excellent fluidity and packing properties. The weight-average molecular weight Mw of the obtained resin E was 4.9 × 10⁻⁶. 5 That was the case.

[0081] (Example 5) Production of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles The inside of a 1 L SUS316 autoclave equipped with an anchor-type stirring blade, a nitrogen inlet tube, and a thermometer was purged with nitrogen. 0.519 g (0.00123 mol) of bis(2,3,4,5,6-pentafluorobenzoyl) peroxide was added as an initiator, 150.0 g (0.615 mol) of perfluoro(4-methyl-2-methylene-1,3-dioxolane) as a monomer, and 1340 g of 1,1,1,3,3,3-hexafluoroisopropanol (hydrogen atom content in solvent molecules: 1.82 wt%, fluorine atoms:hydrogen atoms in solvent molecules = 6:4 (number ratio)) was added as a precipitation polymerization solvent. Precipitation polymerization was carried out by holding the mixture at 55°C for 24 hours under stirring. The liquid containing the purified resin particles was cooled to room temperature, filtered, washed with acetone, and vacuum-dried to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (resin F) (yield: 59%). Table 2 shows the shape, volume-average particle size, 10% particle size, 90% particle size, bulk density, and angle of repose of the obtained resin particles. The obtained resin particles exhibited excellent fluidity and packing properties. The weight-average molecular weight Mw of the obtained resin F was 7.9 × 10⁻⁶. 5 That was the case.

[0082] (Reference example 1) The resin particles obtained in Example 1 were immersed in 10 times the amount of various solvents at 50°C for 5 hours, and the presence of residual resin particles was observed visually.

[0083] The following organic solvents were found to contain residual resin particles visible to the naked eye: 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.

[0084] Subsequently, the mixture was cooled to 25°C, filtered, and then rinsed with the solvent to extract the resin particles. The resin particles were then washed twice with 10 times the amount of acetone, vacuum dried, and the recovery rate was determined from the dry weight. In both cases, the recovery rate was 90% or higher. Furthermore, the filtrate obtained above was removed by distillation, and the amount of solids in the filtrate was determined to be less than 10% of the amount of resin particles used. From these results, it was confirmed that the weight loss rate of the resin was less than 10% by weight.

[0085] (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 resin particles was observed visually. The following organic solvents did not leave any visible resin particles: Hexafluorobenzene, CF3CF2CHCl2 (Hydrogen atom content in solvent molecule: 0.55% by weight, Fluorine atom:Hydrogen atom ratio in solvent molecule = 8:2 (number ratio))

[0086] Visual observation at 50°C revealed that all solutions were transparent with almost no turbidity. After cooling to 25°C, filtration, rinsing with the solvent, and vacuum drying of the filters, the recovery rate was calculated from the weight increase of the filters, and in all cases, it was less than 5% by weight. From these 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]

[0087] This invention provides fluororesin particles with excellent fluidity and filling properties, and a small amount of weight loss when heated, as well as a method for producing fluororesin particles.

Claims

1. Resin particles containing a residue unit represented by the following general formula (1), having a volume average particle diameter of 5 μm or more and 500 μm or less, a 90% particle diameter of 1000 μm or less, and a weight loss amount of 1% by weight or less when heated at 250 °C (however, except when the resin is a copolymer containing 1 mol% or more of perhalo-2,2-di-lower alkyl-1,3-dioxole (each alkyl group independently has 1 to 3 carbon atoms, and its halogen substituent is chlorine or fluorine, provided that each alkyl group has at least 1 fluorine atom)), and except when the resin has an ionic group represented by -(SO ２ X(SO ２ R ｆ )( ａ )( － M ＋ (wherein M ＋ is H ＋ , a monovalent metal cation, or an ammonium ion in which one or more hydrogen atoms may be substituted with a hydrocarbon group, R ｆ is a linear or branched perfluoroalkyl group that may contain an ether-bonding oxygen atom, X is an oxygen atom, a nitrogen atom, or a carbon atom, when X is an oxygen atom a = 0, when X is a nitrogen atom a = 1, and when X is a carbon atom a = 2).), and except when the ion exchange capacity is 0.5 meq / g or more). 【Chemistry 1】 (In formula (1), Rf １ , Rf ２ , Rf ３ , Rf ４ Each of these independently represents 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. Also, Rf １ , Rf ２ , Rf ３ , Rf ４ These atoms may be linked to each other to form a ring with 4 to 8 carbon atoms, and this ring may contain etheric oxygen atoms.

2. The resin particles according to claim 1, wherein the angle of repose is 5° or more and 60° or less.

3. Resin particles according to any one of claims 1 to 2, wherein the angle of repose is 5° or more and 40° or less.

4. The resin particles according to any one of claims 1 to 3, wherein the resin particles are a precipitated polymer.

5. Resin particles according to any one of claims 1 to 4, wherein the bulk density is 0.2 g / mL or more and 1.5 g / mL or less.

6. The resin particles according to any one of claims 1 to 5, wherein the resin particles do not contain an emulsifier and / or a dispersant.

7. The resin particle according to any one of claims 1 to 6, 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). 【Chemistry 2】

8. The resin particles according to any one of claims 1 to 7, characterized in that the 10% particle size is 3 μm or larger.

9. The resin particles according to any one of claims 1 to 8, characterized in that the volume average particle diameter is 5 μm or more and 176 μm or less, and the 90% particle diameter is 308 μm or less.

Images