JP2023159307A - Fluororesin particle and method for producing the same - Google Patents

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

The present invention relates to fluororesin particles having excellent fluidity and filling properties, and a method for producing the same.

Fluorine resins have excellent electrical properties, chemical resistance, waterproofness, and oil and oil repellency, so they are used as protective films for semiconductors and other electronic components, water-repellent films for inkjet printer heads, and water- and oil-repellent coatings for filters. ing.

Among them, fluororesins containing an oxolane ring have a bulky ring structure and therefore are amorphous and have high transparency and high heat resistance. Furthermore, since it is composed only of carbon, fluorine, and oxygen, it has high electrical properties, chemical resistance, waterproofness, and oil and liquid repellency. Furthermore, since it is amorphous, it can be melt-molded.

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 presence of nitrogen fluoride (N ₂ F ₂ ) in a sealed glass tube. No solvent was used, and there is no description of the specific form of the obtained polymer.Non-Patent Document 1 describes that PFMMD is bulk polymerized or solution polymerized 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.

U.S. Patent No. 3,308,107

Macromolecules 2005, 38, 4237

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 deteriorate, but these deteriorations can be reduced by purification. In solution polymerization, after polymerization is performed using one of two types of fluorine-based solvents, chloroform is added to cause precipitation. There is no description of the specific form of the present resin after bulk polymerization purification and the resin obtained by adding chloroform and precipitating it.

As a result of studies by the present inventors, the resins obtained by the methods described in Patent Document 1 and Non-Patent Document 1 had an amorphous non-particulate morphology. Therefore, there was a problem with the fluidity of the resin. For example, it has been found that when melt-molding resin, problems arise in handling, such as difficulty in continuously supplying the resin into the molding machine. Furthermore, since the resins described in Patent Document 1 and Non-Patent Document 1 have the above-mentioned form, for example, when filling the resin into a molding machine, a desired weight of resin cannot be filled into a predetermined volume. It was also found that there was a problem of low gender. In this respect, since a container with a large volume relative to the weight of the resin is required, there is also a problem that the economical efficiency of transporting the article becomes low.

Therefore, in order to solve the above problems, the present invention aims to provide resin particles containing a residue unit represented by general formula (1) and having excellent fluidity and filling properties, and a method for producing the same. .

Further, as a result of further study by the present inventors, the resin produced by the methods described in Patent Document 1 and Non-Patent Documents has an amorphous non-particulate form, so that the inside of the resin It is difficult to remove the entrapped solvent. If the solvent remains in the resin, there is a problem that the amount of weight loss during heating is large, foaming, etc. occurs during molding, and the working environment during molding is deteriorated.

Therefore, an object of the present invention is to provide resin particles containing a residue unit represented by the 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. do.

In addition, in the production of fluororesins, it is generally possible to obtain resin particles by means such as emulsion polymerization and suspension polymerization. However, in these methods, emulsifiers or dispersants are used as polymerization aids. However, the emulsifier or dispersant used remains inside the resin particles and becomes a foreign substance, and further causes coloration when the resin is heated, which may impair transparency and heat resistance. There was a possibility that the strict cleanliness required for semiconductor peripheral parts in recent years could not be met.

Therefore, the present invention provides a method for producing resin particles containing residue units represented by the general formula (1), which have excellent fluidity and filling properties, without using an emulsifier and/or a dispersant, and Another object of the present invention is to provide resin particles containing a residue unit represented by the general formula (1) and containing no dispersant.

Furthermore, the present invention provides resin particles containing residue units represented by general formula (1) that not only have excellent fluidity and filling properties but also have a small thermal weight loss and do not contain an emulsifier and/or a dispersant. The purpose is to provide a method for producing the same.

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. This discovery led to the completion of the present invention.

In formula (1), Rf ₁ , Rf ₂ , Rf ₃ and Rf ₄ 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. Represents one type of a group consisting of a fluoroalkyl group or a cyclic perfluoroalkyl group having 3 to 7 carbon atoms. The perfluoroalkyl group may have an ether oxygen atom. Further, Rf ₁ , Rf ₂ , Rf ₃ and Rf ₄ may be linked to each other to form a ring having 4 or more and 8 or less carbon atoms, and this ring may be a ring containing an etheric oxygen atom.

Furthermore, the present inventors were able to obtain resin particles without using an emulsifier or dispersant by using a precipitation polymerization method using a specific organic solvent; The resin particles do not contain emulsifiers or dispersants and retain the original transparency and heat resistance of the resin.Furthermore, the resin particles have no residual solvent inside the resin particles and have a small weight loss when heated. It has been found that particles can be obtained, leading to a preferred embodiment of the present invention.

The present invention is as follows.
[1]
A resin particle 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), Rf ₁ , Rf ₂ , Rf ₃ , and Rf ₄ are each independently a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, and a branched perfluoroalkyl group having 3 to 7 carbon atoms. Represents one type of the group consisting of a perfluoroalkyl group or a cyclic perfluoroalkyl group having 3 to 7 carbon atoms.The perfluoroalkyl group may have an ether oxygen atom.Also, Rf ₁ , Rf ₂ , Rf ₃ , and Rf ₄ may be linked to each other to form a ring having 4 or more and 8 or less carbon atoms, and the ring may be a ring containing 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], wherein the resin particles are a precipitation polymer.
[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], wherein the resin particles do not contain an emulsifier and/or a dispersant.
[8]
[1] to [ where 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). 7] Particles according to any one of the items.
[9]
A step of obtaining a resin containing a residue unit represented by general formula (4) by placing a mixture of a radical polymerization initiator, a monomer represented by general formula (3) below, and an organic solvent under polymerization conditions. have,
The organic solvent is a solvent that dissolves at least the monomer, does not dissolve at least a portion of the resin produced by polymerization, and causes precipitation of the resin;
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.
(In formula (3), Rf ₅ , Rf ₆ , Rf ₆ , and Rf ₇ are each independently a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, and a branched perfluoroalkyl group having 3 to 7 carbon atoms. represents one of the group consisting of a perfluoroalkyl group or a cyclic perfluoroalkyl group having 3 to 7 carbon atoms.The perfluoroalkyl group may have an ether oxygen atom.Also, Rf ₅ , Rf ₆ , Rf ₆ , and Rf ₇ 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.)
(The definitions of Rf ₅ , Rf ₆ , Rf ₆ , and Rf ₇ in formula (4) are the same as the definitions of Rf ₅ , Rf ₆ , Rf ₆ , and Rf ₇ in formula (3), respectively.)
[10]
The organic solvent described in [9] is 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). manufacturing method.
[11]
The organic solvent contains resin particles containing a residue unit represented by the general formula (4) and having a weight average molecular weight Mw of 5×10 ⁴ to 70×10 ⁴ in an amount 10 times the amount of the resin particles (w/w). ) The manufacturing method according to [10], wherein the organic solvent allows residual resin particles to be confirmed with the naked eye after being immersed in the organic solvent at 50° C. for 5 hours or more.
[12]
The organic solvent contains resin particles containing a residue unit represented by the general formula (4) and having a weight average molecular weight Mw of 5×10 ⁴ to 70×10 ⁴ in an amount 10 times the amount of the resin particles (w/w). ) in an organic solvent at 50°C for 5 hours or more, and after cooling the solution to 25°C, the resin sample remaining in a solid state is collected, and the resin sample is immersed in an organic solvent with a weight loss rate of less than 20% by weight. The manufacturing method according to [10] or [11].
[13]
The manufacturing method according to any one of [9] to [12], characterized in that an organic solvent containing fluorine atoms and hydrogen atoms in the molecule is used.
[14]
14. The manufacturing method according to claim 13, characterized in that an organic solvent is used in which the content of hydrogen atoms in solvent molecules is 1% by weight or more.
[15]
The monomer represented by general formula (3) is perfluoro(4-methyl-2-methylene-1,3-dioxolane) represented by general formula (5), and the monomer represented by general formula (4) is The residue unit according to any one of [9] to [13] is a perfluoro(4-methyl-2-methylene-1,3-dioxolane) residue unit represented by the general formula (6). manufacturing method.

According to the present invention, it is possible to provide fluororesin particles and a method for producing fluororesin particles that have excellent fluidity and filling properties.

Further, according to the present invention, resin particles not only have excellent fluidity and fillability, but also do not contain emulsifiers and dispersants, and a method for producing the same, and not only have excellent fluidity and fillability, but also have a small amount of weight loss on heating. Resin particles and methods for producing the same can be provided respectively.

FIG. 2 is a diagram showing the particle size distribution of resin particles produced in Example 1. is a diagram showing the particle size distribution of resin particles produced in Example 4.

The present invention will be explained in detail below.

The present invention is a resin particle containing a residue unit represented by general formula (1). Since the fluororesin particles of the present invention have a bulky ring structure included in the general formula (1), they are amorphous and have high transparency and high heat resistance. Furthermore, since it is composed only of carbon, fluorine, and oxygen, it has high electrical properties, chemical resistance, waterproofness, and oil and liquid repellency.

In the present invention, Rf ₁ , Rf ₂ , Rf ₃ and Rf ₄ groups in the residue unit represented by general formula (1) are each independently a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, and represents one of the group consisting of 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 ether oxygen atom. Further, Rf ₁ , Rf ₂ , Rf ₃ and Rf ₄ may be linked to each other to form a ring having 4 or more and 8 or less carbon atoms, and this ring may be a ring containing an etheric oxygen atom.

Examples of the linear perfluoroalkyl group having 1 to 7 carbon atoms include trifluoromethyl group, pentafluoroethyl group, heptafluoropropyl group, nonafluorobutyl group, undecafluoropentyl group, tridecafluorohexyl group, Pentadecafluoroheptyl group, etc., and branched perfluoroalkyl groups having 3 to 7 carbon atoms include, for example, heptafluoroisopropyl group, nonafluoroisobutyl group, nonafluoro sec-butyl group, nonafluoro tert-butyl group, etc. Examples of the cyclic perfluoroalkyl group having 3 to 7 carbon atoms include heptafluorocyclopropyl group, nonafluorocyclobutyl group, and tridecafluorocyclohexyl group. Examples of the linear perfluoroalkyl group which may have an etheric oxygen atom having 1 to 7 carbon atoms include -CF ₂ OCF ₃ group, -(CF ₂ ) ₂ OCF ₃ group, -(CF ₂ ) ₂ OCF ₂ CF ₃ group, cyclic perfluoroalkyl group which may have an etheric oxygen atom having 3 to 7 carbon atoms, for example, 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, 2-(2,3,3, Examples include 4,4,5,5-heptafluoro)-furanyl group.

In order to have excellent heat resistance, at least one of Rf ₁ , Rf ₂ , Rf ₃ and Rf ₄ is a linear perfluoroalkyl group having 1 to 7 carbon atoms, or a branched perfluoroalkyl group having 3 to 7 carbon atoms. It is preferably one of the group consisting of a perfluoroalkyl group and a cyclic perfluoroalkyl group having 3 to 7 carbon atoms.

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

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

Since the resin particles of the present invention have a volume average particle diameter of 5 μm or more and 2000 μm or less, 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, since the volume average particle diameter is within the above range, it is possible to suppress the residual solvent in the resin particles, so that the amount of weight loss on heating is small. Incidentally, the residual solvent in the resin particles can also be obtained by obtaining the resin particles by a precipitation polymerization method, which will be described later.

It is more preferable that the resin particles of the present invention have a volume average particle diameter of 5 μm or more and 500 μm or less. When the volume average particle diameter is within this range, fluidity is higher, continuous feeding to a molding machine, etc. is facilitated, and the amount of weight loss upon heating is small. Furthermore, the filling property is increased compared to the resin obtained by the method described in Non-Patent Document 1, and it becomes possible to efficiently store the resin in a container. When the volume average particle diameter is 5 μm or more, the resin particles of the present invention are less likely to be scattered by air currents, and the handleability of the resin particles of the present invention is improved. Further, when the volume average particle diameter is 500 μm or less, it is preferable because the resin particles can be melted in a shorter time and the efficiency of the molding process is improved.

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 even more preferably 1000 μm or less. As a result, in the resin particles of the present invention, the content of coarse particles is reduced, and fluidity and moldability are further improved.

Further, the resin particles of the present invention preferably have a 10% particle diameter of 3 μm or more. As a result, in the resin particles of the present invention, the content of fine particles is reduced, dust formation is further prevented, and fluidity is further improved.

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) using a laser diffraction scattering method. Particle size distribution by laser diffraction scattering method is measured after dispersing resin particles in water or an organic solvent such as methanol, and if necessary, using an ultrasonic homogenizer to uniformize the dispersion state of the particles. By doing so, it is possible to quantify with good reproducibility. As a laser scatterometer, Microtrac manufactured by Microtrac Bell Co., Ltd. can be exemplified.

The volume average particle diameter, also called Mean Volume Diameter, is the average particle diameter expressed on a volume basis.The particle diameter distribution is divided into each particle diameter channel, and the representative particle diameter value of each particle diameter channel is d, and each It is expressed as Σ(vd)/Σ(v), where v is the volume-based percentage for each particle size channel.

The 10% particle diameter refers to the particle diameter at a point where the cumulative amount is 10% when the cumulative amount is calculated with the total volume of the powder group as 100%. The 90% particle diameter refers to the particle diameter at a point where the cumulative amount is 90% when the cumulative amount is calculated with the total volume of the powder group as 100%.

The resin particles of the present invention preferably do not contain emulsifiers and/or dispersants. By not containing an emulsifier and/or a dispersant, the resin and resin particles have excellent transparency and heat resistance. Resin particles containing no emulsifier and/or dispersant can be produced using the precipitation polymerization method described below. Therefore, the resin particles of the present invention are preferably precipitated polymers. Here, the dispersant is an agent that has the function of dispersing resin particles in a solvent, and examples thereof include polyvinyl alcohol, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, and the like. An emulsifier is an agent that has the function of emulsifying resin particles in a solvent, and examples thereof include fluorine-containing surfactants such as sodium perfluorooctanoate, sodium perfluorooctane sulfonate, and ammonium perfluorooctanoate; Examples include non-fluorine surfactants such as sodium lauryl sulfate and ethylene glycol polymers.

The bulk density of the resin particles of the present invention is preferably 0.2 g/cm ³ or more and 1.5 g/cm ^{3 or} less from the viewpoint of filling properties. The bulk density can be measured by the method described in Examples below.

The resin particles of the present invention may contain other monomer residue units, and examples of other monomer residue units include tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and chlorotrifluoropropylene. Fluoroethylene (CTFE), trifluoroethylene, hexafluoroisobutylene, perfluoroalkyl ethylene, fluorovinylether, vinyl fluoride (VF), vinylidene fluoride (VDF), perfluoro-2,2-dimethyl-1,3-dioxole (PDD), perfluoro(allyl vinyl ether), perfluoro(butenyl vinyl ether), and the like.

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 and facilitates continuous supply to a molding machine or the like. 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.

Here, the angle of repose refers to the angle formed between the plane and the ridgeline of the powder when resin powder is deposited on the plane. The angle of repose can be evaluated by filling a container with resin powder, letting it fall naturally, and measuring the angle formed by the pile of resin powder when it is deposited on a horizontal surface. A specific method for measuring the angle of repose will be described in Examples described later.

In the present invention, there is no restriction on the molecular weight of the resin particles, and for example, the weight average molecular weight measured by gel permeation chromatography (GPC) may be 2,500 to 2,000,000. From the viewpoint of the melt viscosity of the resin and mechanical strength, it is preferably 10,000 to 1,000,000 (g/mol). In the measurement, 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.

Next, a method for producing resin particles of the present invention will be explained.

The resin particles of the present invention can be produced, for example, by 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 residue represented by the general formula (3). It can be produced by a method including a step of obtaining a resin containing a base unit.

In formula (3), Rf ₅ , Rf ₆ , Rf ₇ and Rf ₈ have the same meanings as Rf ₁ , Rf ₂ , Rf ₃ and Rf ₄ in formula (1), respectively.

In formula (4), Rf ₅ , Rf ₆ , Rf ₇ , and Rf ₈ have the same meanings as Rf ₁ , Rf ₂ , Rf ₃ , and Rf ₄ in formula (1), respectively.

In the method for producing resin particles of the present invention, the organic solvent dissolves at least the monomer represented by general formula (3) and dissolves the residue unit represented by general formula (4) produced by polymerization. The organic solvent is a solvent that does not dissolve at least a portion of the resin contained therein but causes the resin to precipitate, and the resin produced by the polymerization precipitates as particles in the organic solvent. 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 must be an organic solvent that dissolves the monomer represented by general formula (3) but does not dissolve the resin containing the residue unit represented by general formula (4). This precipitation polymerization solvent is hereinafter referred to as precipitation polymerization solvent A. In the present invention, by using a precipitation polymerization solvent, the resin produced by the polymerization reaction can be precipitated as particles having a specific volume average particle diameter, and as a result, resin particles with excellent moldability and fillability can be manufactured. I can do it. Furthermore, since polymerization aids such as emulsifiers and dispersants are not used, resin particles can be produced that do not contain emulsifiers and dispersants that cause deterioration of transparency and heat resistance.

Here, the precipitation polymerization solvent A means a solvent in which resin particles remain after resin particles containing a residue unit represented by general formula (4) are immersed in the organic solvent for a long time. Specifically, resin particles containing a residue unit represented by the general formula (4) and having a weight average molecular weight Mw of 5 x 10 ⁴ to 70 x 10 ⁴ are used in an amount (w/w) 10 times the amount of the resin particles. If residual resin particles can be seen with the naked eye in the organic solvent after being immersed in the organic solvent at 50° C. for 5 hours or more, the organic solvent can be regarded as the precipitation polymerization solvent A. Precipitation polymerization solvent A is an organic solvent in which the resin sample remaining in a solid state is recovered after immersion at 50°C for 5 hours or more and the solution is cooled to 25°C, and the weight loss rate of the resin sample is less than 20% by weight. It is preferable that The weight loss rate of the resin sample is more preferably less than 12% by weight, even more preferably less than 10% by weight.

The rate of decrease in resin weight can be measured by the following method. After the cooled solution is filtered, the solid on the filter is rinsed with the solvent, washed multiple times with acetone and dried, and the resin sample on the filter is collected. Measure the weight of the recovered resin, and calculate the resin reduction rate by dividing the value obtained by subtracting the recovered resin weight from the amount of resin immersed in the organic solvent by the amount of resin immersed in the organic solvent. do.

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

Further, as the precipitation polymerization solvent, an organic solvent containing a fluorine atom and a hydrogen atom in the molecule is preferable because a chain transfer reaction is difficult to occur in radical polymerization, the polymerization yield is excellent, and a high molecular weight product is easily obtained. Specific examples of precipitation polymerization solvents containing fluorine atoms and hydrogen atoms in the molecule include 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 2,2,2-trifluoroethyl ether, and 2,2,2-trifluoroethyl ether. Fluoroethanol, 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-dodecafluorohepta alcohol, 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-hexafluoropropylethyl ether, 2,2,3,4,4,4-hexafluorobutyl difluoromethyl ether, and the like.

Among them, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 2,2,2-trifluoroethanol, 1,1,1,3,3,3-hexafluoro Isopropanol, 1,2,2,3,3,4,4-heptafluorocyclopentane are preferred, and 1,2,2,3,3,4, 4-Heptafluorocyclopentane is preferred. The ratio of fluorine atoms to 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 ratio of atoms, since the polymerization yield is excellent. The ratio is more preferably 9 to 7:3, and even more preferably 4:6 to 7:3.

The precipitation polymerization solvent preferably contains a fluorine atom and a hydrogen atom in its molecule, and the content of hydrogen atoms in the solvent is preferably 1% by weight or more based on the weight of the solvent molecule, since it has an excellent polymerization yield.1. More preferably, the amount is 5% by weight or more. Further, since the polymerization yield is excellent and it is easy to obtain a high molecular weight product, the amount is preferably 1% by weight or more and 5% by weight or less, and preferably 1.5% by weight or more and 4% by weight or less. Further, as the precipitation polymerization solvent, one that does not contain a chlorine atom in the molecule is preferable because it has an excellent polymerization yield and is easy to obtain a high molecular weight product.

The ratio of the monomer represented by the general formula (3) to the precipitation polymerization solvent is 1:monomer:precipitation polymerization solvent=1: The ratio is preferably 99 to 50:50, more preferably 5:95 to 40:60, even more preferably 5:95 to 30:70.

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

In the production method of the present invention, the monomer represented by general formula (3) is perfluoro(4-methyl-2-methylene-1,3-dioxolane) represented by general formula (5), The residue unit represented by formula (4) is preferably a perfluoro(4-methyl-2-methylene-1,3-dioxolane) residue unit represented by general formula (6).

Since the resin particles of the present invention become resin particles that are difficult to foam during molding, the amount of weight loss upon heating at 250°C is preferably 1% by weight or less, and preferably 0.5% by weight or less. . Further, there is no particular limitation on the minimum amount of weight loss upon heating at 250° C., but for example, 0.001% by weight or more can be exemplified. Furthermore, 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. is preferred. Here, the amount of weight loss upon heating at 250°C refers to the amount of weight loss at 250°C when the temperature is raised from 40°C at 10°C/min under an air flow using TG-DTA, (1- (Sample weight at 250°C)/(Weighed sample weight))×100).

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

<Volume average particle diameter>
The volume average particle diameter (unit: μm) was measured using MT3000 manufactured by Microtrack Co., Ltd. and methanol as a dispersion medium.

<10% particle size>
The 10% particle diameter (unit: μm) was measured using MT3000 manufactured by Microtrack Co., Ltd. and methanol as a dispersion medium.

<90% particle size>
The 90% particle diameter (unit: μm) was measured using MT3000 manufactured by Microtrack Co., Ltd. and methanol as a dispersion medium.

<Liquidity>
The case where the shape of the resin was particulate was rated as good (〇), and the case where the shape was not particulate was rated as poor (x).

<Bulk density>
The resin particles were dropped and filled up to the 50 mL mark line on the graduated cylinder without applying impact to the graduated cylinder. The weight (g) of the resin particles per 50 mL of this volume was measured. The bulk density (g/mL) was calculated by dividing the weight of the resin particles by the volume.

<Fillability>
A bulk density of 0.2 g/mL or more was evaluated as good (○), and a bulk density of less than 0.2 g/mL was evaluated as poor (×).

<Weight average molecular weight Mw>
The measurement was performed using a gel permeation chromatography equipped with a column TSKgel SuperHZM-M manufactured by Tosoh Corporation and an RI detector. As an eluent, Asahiklin AK-225 (manufactured by Asahi Glass Co., Ltd.) was added with 10 wt% of 1,1,1,3,3,3-hexafluoro-2-propanol (manufactured by Wako Pure Chemical Industries, Ltd.) relative to AK-225. was used. Using standard polymethyl methacrylate manufactured by Agilent as a standard sample, the weight average molecular weight Mw in terms of polymethyl methacrylate 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 manufactured by Hitachi High-Tech Science Co., Ltd.), and placed under a stream of instrumentation air (160 mL) using a TG/DTA device (TG/DTA6200AST2 manufactured by Hitachi High-Tech Science Co., Ltd.). /min) from 40 °C to 300 °C at a rate of 10 °C/min, and the amount of weight loss at 250 °C (1 - (sample weight at 250 °C) / (weighed sample weight)) x 100) was determined. It was defined as the amount of weight loss after heating at °C.

<Angle of repose>
Fill a sample bottle with 7 ml of resin powder, and place it on a circular stand (made of glass) with a diameter of 4 cm using a glass powder funnel (manufactured by As One Co., Ltd., diameter of the upper part of the funnel 50 mm, diameter of the lower part of the funnel 10 mm, total length of the funnel 100 mm, Fix the powder funnel (with a height of 40 mm) so that the bottom end of the powder funnel is 4 cm above the circular platform, and use the funnel to drop the resin powder from the height of the top of the funnel to see the pile that forms when it accumulates. The angle (°) of the slope was measured using a protractor. (In the comparative example, the resin powder was dropped without using a powder funnel because the fluidity of the resin powder was poor.)

(Example 1) Production 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 introduction tube, and a thermometer was replaced with nitrogen. did. 1.288 g (0.00305 mol) of bis(2,3,4,5,6-pentafluorobenzoyl) peroxide as an initiator, perfluoro(4-methyl-2-methylene-1,3- dioxolane) 150.0 g (0.615 mol), Asahiklin AE-3000 (manufactured by Asahi Glass Co., Ltd., 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, solvent molecule) as a precipitation polymerization solvent. Hydrogen atom content: 1.51% by weight, fluorine atoms: hydrogen atoms in solvent molecules = 7:3 (number ratio)) was added, and precipitation polymerization was carried out by holding at 55 ° C. for 24 hours with stirring. went. Cool to room temperature, filter the liquid containing purified resin particles, wash with acetone, and vacuum dry to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (resin A). was obtained (yield: 56%). Table 1 shows the shape, volume average particle diameter, 10% particle diameter, 90% particle diameter, bulk density, and angle of repose of the obtained resin particles. 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 .

(Comparative Example 1) Production of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin Bis(2,3,4,5,6-pentafluorobenzoyl) was used as an initiator in a 75 mL glass ampoule. 0.017 g (0.0000407 mol) of peroxide, 5.0 g (0.0205 mol) of perfluoro(4-methyl-2-methylene-1,3-dioxolane) as a monomer, and hexafluorobenzene (0.0205 mol) as a polymerization solvent. Content of hydrogen atoms in solvent molecules: 0% by weight, 8.2 g of fluorine atoms: hydrogen atoms in solvent molecules = 10:0 (number ratio)), and after repeating nitrogen substitution and depressurization, under reduced pressure. Melted. This ampoule was placed in a constant temperature bath at 55° C. and maintained for 24 hours to perform radical solution polymerization, and a viscous liquid in which the resin was dissolved was obtained. After cooling to room temperature, the ampoule was opened and the resin solution was diluted with 36 g of hexafluorobenzene to adjust the viscosity to prepare a diluted resin solution. Add 1 L of chloroform to a beaker equipped with anchor blades, and add the diluted resin solution to the chloroform while stirring to precipitate the resin. By vacuum drying, perfluoro(4-methyl-2-methylene -1,3-dioxolane) resin (resin D) was obtained (yield: 61%). The weight average molecular weight Mw of the obtained resin D was 3.5×10 ⁵ . Table 1 shows the shape, bulk density, and angle of repose of the obtained resin. Since the resin was amorphous, the volume average particle diameter could not be measured. In this case, the resin obtained had problems with fluidity and filling properties.

(Example 2) Production 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 introduction tube, and a thermometer was replaced with nitrogen. did. Bis(2,3,4,5,6-pentafluorobenzoyl) peroxide 0.346 g (0.000820 mol) as an initiator, perfluoro(4-methyl-2-methylene-1,3- dioxolane) 100.0 g (0.410 mol), 2,2,2-trifluoroethanol as a precipitation polymerization solvent (content of hydrogen atoms in solvent molecules: 3.03% by weight, fluorine atoms in solvent molecules: hydrogen Precipitation polymerization was performed by adding 890 g of atoms = 5:5 (number ratio) and holding at 55°C for 24 hours with stirring. Cooled to room temperature, filtered the liquid containing purified resin particles, and washed with acetone. Perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (resin B) were obtained by vacuum drying (yield: 78%).The shape and volume of the obtained resin particles The average particle diameter, 10% particle diameter, 90% particle diameter, bulk density, and angle of repose are shown in Table 1.The obtained resin particles had excellent fluidity and filling properties.Weight of obtained resin B The average molecular weight Mw was 1.1×10 ⁵ .

(Example 3) Production 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 introduction tube, and a thermometer was replaced with nitrogen. did. Bis(2,3,4,5,6-pentafluorobenzoyl) peroxide 0.519 g (0.00123 mol) as an initiator, perfluoro(4-methyl-2-methylene-1,3- dioxolane) and 1150 g of chloroform as a precipitation polymerization solvent were added, followed by precipitation polymerization by holding at 55° C. for 24 hours with stirring. Cool to room temperature, filter the liquid containing purified resin particles, wash with acetone, and vacuum dry to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (resin C). was obtained (yield: 19%). Table 1 shows the shape, volume average particle diameter, 10% particle diameter, 90% particle diameter, bulk density, and angle of repose of the obtained resin particles. The obtained resin particles had excellent fluidity and filling properties. The weight average molecular weight Mw of the obtained resin C was 7.0×10 ³ .

(Example 4) Production 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 introduction tube, and a thermometer was replaced with nitrogen. did. 1.038 g (0.00246 mol) of bis(2,3,4,5,6-pentafluorobenzoyl) peroxide as an initiator, perfluoro(4-methyl-2-methylene-1,3- dioxolane) 300.0 g (1.23 mol), Zeorola-H (Nippon Zeon Co., Ltd., 1,2,2,3,3,4,4-heptafluorocyclopentane) as a precipitation polymerization solvent, Content: 1.55% by weight, 1200g of fluorine atoms:hydrogen atoms in solvent molecules = 7:3 (number ratio)) was added, and precipitation polymerization was carried out by holding at 55°C for 24 hours with stirring. Cool to room temperature, filter the liquid containing purified resin particles, wash with acetone, and vacuum dry to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (resin E). was obtained (yield: 86%). Table 2 shows the shape, volume average particle diameter, 10% particle diameter, 90% particle diameter, bulk density, and angle of repose of the obtained resin particles. 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 .

(Example 5) Production 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 introduction tube, and a thermometer was replaced with nitrogen. did. Bis(2,3,4,5,6-pentafluorobenzoyl) peroxide 0.519 g (0.00123 mol) as an initiator, perfluoro(4-methyl-2-methylene-1,3- dioxolane) 150.0 g (0.615 mol), 1,1,1,3,3,3-hexafluoroisopropanol as precipitation polymerization solvent (content of hydrogen atoms in solvent molecule: 1.82% by weight, solvent molecule 1,340 g of fluorine atoms:hydrogen atoms=6:4 (number ratio)) was added thereto, and precipitation polymerization was carried out by holding the mixture at 55° C. for 24 hours with stirring. Cool to room temperature, filter the liquid containing purified resin particles, wash with acetone, and vacuum dry to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (resin F). was obtained (yield: 59%). Table 2 shows the shape, volume average particle diameter, 10% particle diameter, 90% particle diameter, bulk density, and angle of repose of the obtained resin particles. 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 .

(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 whether the resin particles remained was visually observed.

・The organic solvents in which residual resin particles were visually confirmed 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.

Thereafter, the resin particles were cooled to 25°C, filtered through a filter, and rinsed with the solvent to remove the resin particles. The resin particles were washed twice with 10 times the amount of acetone, vacuum dried, and the recovery rate was determined from the dry weight. The recovery rate was over 90% in all cases. Further, when the filtrate obtained above was distilled off and the solid content in the filtrate was determined, the solid content in the filtrate was less than 10% based on the resin particles used. From the above results, it was confirmed that the weight reduction 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 the various solvents listed below at 50° C. for 5 hours, and whether or not the resin particles remained was visually observed.
・Organic solvents in which no resin particles remained with the naked eye are as follows:
Hexafluorobenzene, CF ₃ CF ₂ CHCl ₂ (content of hydrogen atoms in solvent molecules: 0.55% by weight, fluorine atoms: hydrogen atoms in solvent molecules = 8:2 (number ratio))

As a result of visual observation at 50°C, all solutions were transparent, with almost no turbidity observed. Thereafter, the solution was cooled to 25° C., filtered, rinsed with the solvent, vacuum dried, and the recovery rate calculated from the increase in weight of the filter, which was 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.

The present invention provides fluororesin particles that have excellent fluidity and fillability and a small amount of weight loss on heating, and a method for producing fluororesin particles.

Claims (15)

A resin particle 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), Rf ₁ , Rf ₂ , Rf ₃ , and Rf ₄ are each independently a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, and a branched perfluoroalkyl group having 3 to 7 carbon atoms. Represents one type of the group consisting of a perfluoroalkyl group or a cyclic perfluoroalkyl group having 3 to 7 carbon atoms.The perfluoroalkyl group may have an ether oxygen atom.Also, Rf ₁ , Rf ₂ , Rf ₃ , and Rf ₄ may be linked to each other to form a ring having 4 or more and 8 or less carbon atoms, and the ring may be a ring containing an etheric oxygen atom.) The resin particles according to claim 1, wherein the volume average particle diameter is 5 μm or more and 500 μm or less. The resin particles according to claim 1 or 2, having an angle of repose of 5° or more and 60° or less. The resin particles according to any one of claims 1 to 3, wherein the resin particles are a precipitation polymer. The resin particles according to any one of claims 1 to 4, having a bulk density of 0.2 g/mL or more and 1.5 g/mL or less. The resin particles according to any one of claims 1 to 5, which have a weight loss of 1% by weight or less when heated at 250°C. The resin particles according to any one of claims 1 to 6, wherein the resin particles do not contain an emulsifier and/or a dispersant. Claims 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). Particles according to any one of the above.
A step of obtaining a resin containing a residue unit represented by general formula (4) by placing a mixture of a radical polymerization initiator, a monomer represented by general formula (3) below, and an organic solvent under polymerization conditions. have,
The organic solvent is a solvent that dissolves at least the monomer, does not dissolve at least a portion of the resin produced by polymerization, and causes precipitation of the resin;
The method for producing resin particles according to any one of claims 1 to 7, wherein the resin produced by the polymerization is precipitated as particles in an organic solvent.
(In formula (3), Rf ₅ , Rf ₆ , Rf ₆ , and Rf ₇ are each independently a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, and a branched perfluoroalkyl group having 3 to 7 carbon atoms. represents one of the group consisting of a perfluoroalkyl group or a cyclic perfluoroalkyl group having 3 to 7 carbon atoms.The perfluoroalkyl group may have an ether oxygen atom.Also, Rf ₅ , Rf ₆ , Rf ₆ , and Rf ₇ 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.)
(The definitions of Rf ₅ , Rf ₆ , Rf ₆ , and Rf ₇ in formula (4) are the same as the definitions of Rf ₅ , Rf ₆ , Rf ₆ , and Rf ₇ in formula (3), respectively.) According to claim 9, the organic solvent is an organic solvent that dissolves the monomer represented by the general formula (3) and does not dissolve the resin containing the residue unit represented by the general formula (4). manufacturing method. The organic solvent contains resin particles containing a residue unit represented by the general formula (4) and having a weight average molecular weight Mw of 5×10 ⁴ to 70×10 ⁴ in an amount 10 times the amount of the resin particles (w/w). 11. The manufacturing method according to claim 10, wherein the organic solvent is such that residual resin particles can be visually confirmed in the organic solvent after being immersed in the organic solvent at 50° C. for 5 hours or more. The organic solvent contains resin particles containing a residue unit represented by the general formula (4) and having a weight average molecular weight Mw of 5×10 ⁴ to 70×10 ⁴ in an amount 10 times the amount of the resin particles (w/w). ) in an organic solvent at 50°C for 5 hours or more, and after cooling the solution to 25°C, the resin sample remaining in a solid state is collected, and the resin sample is immersed in an organic solvent with a weight loss rate of less than 20% by weight. The manufacturing method according to claim 10 or 11. The manufacturing method according to any one of claims 9 to 12, characterized in that an organic solvent containing fluorine atoms and hydrogen atoms in the molecule is used. 14. The manufacturing method according to claim 13, characterized in that an organic solvent is used in which the content of hydrogen atoms in solvent molecules is 1% by weight or more. The monomer represented by general formula (3) is perfluoro(4-methyl-2-methylene-1,3-dioxolane) represented by general formula (5), and the monomer represented by general formula (4) is The production according to any one of claims 9 to 13, wherein the residue unit is a perfluoro(4-methyl-2-methylene-1,3-dioxolane) residue unit represented by general formula (6). Method.