KR20180068839A - Fluororesin-aluminum oxide mixed dispersion and method of manufacturing the same - Google Patents

Abstract

The present invention aims to provide a fluorinated resin-aluminum oxide mixed dispersion, in which fluorinated resin fine particles and aluminum oxide fine particles are uniformly floated and dispersed together in an aqueous solvent. The fluorinated resin-aluminum oxide mixed dispersion is an aqueous dispersion obtained by mixing an aqueous dispersion of the fluorinated resin fine particles and a sol of the aluminum oxide fine particles, in which the fluorinated resin fine particles and the aluminum oxide fine particles are floated and dispersed together to maintain the dispersion state for three days or more. It is preferable that the heat resistance of solids obtained by evaporation and scattering of the solvent from the fluorinated resin-aluminum oxide mixed dispersion is 330°C or higher.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a fluorinated resin-aluminum oxide mixed dispersion,

The present invention relates to surfaces of various materials such as metals, carbon, plastic, glass, ceramics, wood and the like, coating liquid for coating the surfaces of products made of these materials, impregnating liquids of fibers and powders of the materials, and methods for producing the same.

The fluororesin is superior in heat resistance and cold resistance to ordinary plastics and organic polymers such as polyethylene and polypropylene, has high resistance to various chemicals including acid and alkali, that is, has high chemical resistance and corrosion resistance, is incombustible, Not only the enemy, but also non-adhesive and non-wetting water and oil. In addition, since fluorine resin is low in friction and has moderate elasticity, it is actively used in coating of various materials and products such as moldings, containers, electric wires, thermometers, various sensors, gaskets and packing, and frying pans. Such a coating is usually formed by lining a fluorine resin film or by coating or impregnating a fluorine resin fine particle dispersion. Accordingly, not only a variety of various fluorine resin films and dispersions are commercially available, but also new products are being actively developed (for example, Patent Document 1).

As is known, the heat resistance of a fluorine-based resin product is generally higher than that of a conventional organic polymer product. However, since it causes thermal deterioration at 200 deg. C, care must be taken when the product is used over a long period of time even at a temperature near 200 deg. Do. Further, if the use temperature is higher, the thermal deterioration becomes sharp, of course, and the risk of toxic gases such as fluorine gas, hydrogen fluoride gas and hydrofluoric acid being discharged is also increased. For this reason, measures and measures are required to improve the heat resistance of the Teflon (registered trademark) resin, and to trap the toxic gas generated by decomposition to suppress the discharge to the outside of the system.

BACKGROUND ART [0002] Conventionally, various kinds of metal oxides, fine particles of metal, and fibers have been widely used in plastics not only for fluorine resins but also for various organic polymers, in terms of processability, weatherability, durability, rigidity, impact resistance, It is usually added as a filler in order to improve flame retardancy, heat resistance, sound insulation, gas shielding property and the like, or to improve surface characteristics such as antistatic property and frictional property. Examples of the additive (filler) include various ones such as talc, mica, silica, titania, alumina, magnesia, graphite, molybdenum sulfide, calcium carbonate and iron powder.

Alumina, especially aluminum oxide containing hydroxyl groups having a hydroxyl group such as boehmite and gibbsite causes water release and / or phase change by heating, so that heat resistance imparting agent (filler) It is known to be useful as a flame retardant filler. They are actually added for imparting heat resistance or for flame retardation to thermoplastic resins such as unsaturated polyester, thermosetting resins such as unsaturated polyester, acrylic, phenol, epoxy, polyurethane and melamine, rubber, elastomer such as natural rubber and synthetic rubber, acrylic and polyethylene Non-Patent Document 1).

However, in the fluorine resin, it is reported that the heat resistance and the flame retardancy of the fluorine resin are improved and improved due to the addition and incorporation of alumina, especially aluminum oxide containing hydroxyl group, specifically aluminum hydroxide, gibbsite, bayerite, boehmite and diaphore And the effect of the hydroxyl group-containing aluminum oxide on the heat resistance and the flame retardancy of the fluorine-based resin has not been confirmed as a clear experimental fact at all.

Further, regarding the mixed dispersion of the aqueous dispersion or emulsion of the fluoric resin fine particles with the sol of the hydroxyl group-containing aluminum oxide, the so-called alumina sol, no mention is made of the product as well as the product. This is presumably because the inorganic fine particle dispersion suitable for mixing with the fluorine-based resin fine particle dispersion is originally used, and the sol itself tends to cause viscosity increase or gelation with respect to alumina sol, and storage stability is also insufficient. For this reason, the mixing of the fluoric resin fine particle dispersion and the metal oxide filler solution (sol) is almost made up of silica sol or organosilicate solution excellent in viscosity stability (Patent Documents 1 to 6).

Actually, in Patent Documents 2 to 4, the uniformly mixed dispersion liquid is prepared by mixing the emulsion of the fluorine resin with the colloidal sol solution of the inorganic microfine particles, and not only silicon oxide (silica) but also titanium oxide, zeolite, aluminum oxide, zinc oxide , And antimony pentoxide are preferable, and silicon carbide, silicon nitride, aluminum nitride, lead oxide, tin oxide, magnesium oxide and the like can be used, and all of the examples are limited to silica. There are no examples of the colloid solution of the inorganic microparticles other than silica at all, and there is no mention or description of the composition and composition of the inorganic microparticle sol used for mixing, It is nothing more than what is written.

In addition, Patent Documents 2 to 4, particularly Patent Document 2, disclose that when a fluororesin-silica mixed dispersion obtained by mixing a fluororesin aqueous dispersion and a silica sol is applied directly to a substrate and dried, the fluororesin primary particles and Silica nanoparticles are separated and agglomerated, and a silica nanoparticle aggregate having a size of several micrometers appears on the surface of the film after the calcination (heat treatment), and since silica is omnipresent, it is not suitable to use the mixed solution as it is. (PH adjustment), or coagulation of the dispersion liquid at one time by freeze drying or the like is essential for achieving a uniform distribution after drying.

As described above, no specific examples are found in commercial products as well as in the literature as to the mixed dispersion of the aqueous dispersion of the fluoric resin microparticles or the emulsion and the alumina sol. It is not easy to prepare a mixed dispersion solution of the inorganic fine particles other than the silicon oxide inorganic fine particles and the fluoric resin, and from Patent Document 2, it is obtained by evaporating and drying the mixed dispersion to achieve uniform dispersion of the inorganic fine particles in the solid mixture It is more difficult to do.

Japanese Patent Application Laid-Open No. 2006-117900 Japanese Patent Application Laid-Open No. 2007-119769 Japanese Patent Application Laid-Open No. 2008-115335 Japanese Patent Application Laid-Open No. 2008-115336 Japanese Patent Application Laid-Open No. 8-258228 Japanese Patent Laid-Open Publication No. 2012-219126

Japan Rubber Society, Vol. 75, No. 8, 330-332 (2002) PLASTICS AGE, April 2006, 72-80 Journal of the Rubber Society of Japan, Vol. 82, No. 2, 61-66 (2009)

An object of the present invention is to provide a fluorinated resin-aluminum oxide mixed dispersion in which fluorine resin fine particles and aluminum oxide fine particles are suspended and dispersed uniformly in an aqueous solvent.

In view of these circumstances, the inventors have extensively searched for the combination of the aqueous dispersion of the fluorine-based resin and the emulsion and the metal oxide colloidal sol, and repeated trial and error about their mixing and combining methods, (Sol) in which fluorine resin fine particles and aluminum oxide fine particles are uniformly suspended and dispersed in an aqueous solvent.

The invention according to claim 1 is an aqueous dispersion obtained by mixing an aqueous dispersion of fluoric resin fine particles and an aluminum oxide fine particle sol, wherein the fluoric resin fine particles and aluminum oxide fine particles are suspended and dispersed together to stably maintain the main dispersion state for 3 days or more Based resin-aluminum oxide mixed dispersion.

The invention according to claim 2 is the fluorinated resin-aluminum oxide mixed dispersion according to claim 1, wherein the solid obtained by evaporating the solvent from the fluorinated resin-aluminum oxide mixed dispersion has a heat resistance of 330 ° C or more.

The invention according to claim 3 is characterized in that the aluminum oxide is uniformly distributed and dispersed in the solid material obtained by evaporating the solvent from the fluorine resin-aluminum oxide mixed dispersion liquid, Based resin-aluminum oxide mixed dispersion.

The invention according to claim 4 is characterized in that the pH in the aqueous dispersion of the fluorine resin fine particles is 3.5 to 10.2, and the fluorine resin fine particles are tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, perfluoro Aluminum oxide mixed dispersion according to any one of claims 1 to 3, which is a resin fine particle made of a polymer or copolymer of a monomer selected from vinylidene fluoride and vinyl fluoride.

The invention according to claim 5 is the fluorinated resin-aluminum oxide mixed dispersion according to any one of claims 1 to 4, wherein the aluminum oxide fine particles in the aluminum oxide fine particle sol are aluminum oxide fine particles having an oxo (OH) group.

The invention according to claim 6 is characterized in that the pH of the hydroxyl group-containing aluminum oxide fine particle sol is 2.5 to 7.0, the hydroxyl group-containing aluminum oxide fine particles in the sol are boehmite or diaspore (composition formula: AlOOH), and the particle size is 5 to 4500 nm Based resin-aluminum oxide mixed dispersion according to claim 5.

According to a seventh aspect of the present invention, in the fluororesin-aluminum oxide mixed dispersion, the weight ratio of the fluoric resin fine particles to the content of Al ₂ O _{3 as} the hydroxyl group-containing aluminum oxide fine particles in the liquid is 3.1-100, the weight ratio of water is 10-120 Based resin-aluminum metal oxide mixed dispersion according to claim 5 or 6.

The invention according to claim 8 is the fluorinated resin-aluminum oxide mixed dispersion according to any one of claims 1 to 7, wherein the pH is 3.5 to 10.2.

The invention according to claim 9 is a process for producing an aqueous dispersion of fluorine-based resin fine particles having a pH of 3.5 to 10.2 and a hydroxyl group-containing aluminum oxide fine particle sol having a pH of 2.5 to 7.0 at a temperature ranging from 5 to 100 ° C, Aluminum oxide mixed dispersion characterized in that the weight ratio of fluoric resin fine particles to the content of ₂ O ₃ is set to 3.1 to 100 and the weight ratio of water to 10 to 120 is mixed and manufactured.

In the fluorine-based resin-aluminum oxide mixed dispersion of the present invention, the fluorine-based resin and the fine particles of the aluminum oxide do not aggregate or aggregate to cause precipitation, and even if they have their original size and slightly aggregated, they have a size close to the original size, Dispersed in a water solvent in such a size as to be suspended and dispersed in a water solvent.

Thus, it is possible to form an alumina-added Teflon (registered trademark) layer coating to a thickness of freely with a very simple operation or operation of applying, impregnating or dipping (immersing) the mixed dispersion liquid of the present invention to the coating object and drying and heat- And thus can be carried out nonporously. In addition, since the operation and operation using the mixed dispersion of the present invention is simple, it is not only energy saving, but also very safe and economical.

1 (a) is a gas chromatographic mass spectrometry of a fluorine resin powder obtained by evaporating, drying (drying) and drying an aqueous fluorine resin fine particle dispersion, and (b) Is a gas-liquid mass spectrometry of a mixed powder of fluorine-based resin and alumina obtained by evaporation, drying, and drying.
2 is an elemental qualitative analysis chart of the pyrolysis residue of the alumina-added fluororesin film of the present invention.
3 is an SEM image of the powder obtained by the evaporation drying of the fluororesin-alumina oxide mixed dispersion of the present invention.
Fig. 4 is a photograph of an embodiment of the fluorine resin-alumina oxide mixed dispersion of the present invention and a photograph of a comparative example.

<Composition of Fluorine-Based Resin-Aluminum Oxide Mixed Dispersion>

The fluorinated resin-aluminum oxide mixed dispersion of the present invention is basically a suspension dispersion of fluorine resin fine particles and aluminum oxide fine particles composed of fluorine resin fine particles, aluminum oxide fine particles and water.

Here, the fluoric resin fine particles are polymers or copolymers of monomers selected from tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, perfluoro (alkyl vinyl ether), vinylidene fluoride and vinyl fluoride . Among them, those dispersed in water are used for preparing the fluororesin-aluminum oxide mixed dispersion of the present invention.

The aluminum oxide fine particles in the present invention include aluminum oxide (composition formula: Al ₂ O ₃ ), amorphous aluminum hydroxide, gibbsite, bayerite (composition formula: Al (OH) ₃ ] and / or boehmite or diaspore ], And an aqueous colloidal sol of these fine particles is used to obtain the fluorinated resin-aluminum oxide mixed dispersion of the present invention.

Whether fluorine resin fine particles or metal oxide fine particles are present, it is usually easy for the particles to settle and precipitate as their molecular weight and size increase. Therefore, in order for the fine particles of the fluorine resin and the aluminum oxide to retain the suspended dispersion state in the aqueous solvent for a long period of time, the molecular weight of the particles and the size of the particles should be small. More specifically, the fluorine-based resin fine particles preferably have an average molecular weight of 1 × 10 ⁴ to 1 × 10 ⁷ , more preferably 2 × 10 ⁴ to 1 × 10 ⁷ . If it is smaller than this range, the coating film tends to be retracted, and if it is larger than this range, the melt viscosity tends to be too high to make the PTFE particles hardly fuse together.

In the fluorine resin fine particles, the particle size is preferably in the range of 100 to 500 nm, and in the aluminum oxide fine particles, the particle size is preferably in the range of 5 to 4500 nm. However, as long as the fluoric resin microparticles are stably and uniformly suspended and dispersed in an aqueous solvent, the range of the above-mentioned molecular weight and the size of the fluoric resin microparticles are not specifically specified or mentioned.

It is important to consider not only the affinity with the solvent for the uniform suspension suspension of the particles in the solvent but also to avoid aggregation of the particles. The cohesion increases the viscosity, causing coagulation and gelation, and also causing precipitation. Therefore, it is necessary to prevent aggregation and agglomeration of the particles. As a countermeasure therefor, there is a method in which particles are repulsed with each other by the same charge (by electrification) and the particles are surrounded by a surfactant to form a complex micelle And so on.

In the case of the metal oxide colloid, it is overwhelming that the particles are dispersed by repulsion between the particles even when the particles are made into complex micelles. The charged amount of the particles is closely related to the pH of the solution, in other words, it is extremely sensitive to pH. Therefore, the pH of the aluminum oxide fine particle sol used for preparing the fluororesin-aluminum oxide mixed dispersion of the present invention also has a suitable range for preventing the flocculation.

Specifically, in order to prevent agglomeration between the aluminum oxide fine particles and the fluorine resin fine particles, the pH of the aluminum oxide fine particle sol used in the present invention is less than 7.5, preferably from pH 2.5 to 7.0. When the pH of the aluminum oxide fine particle sol is 7.5 or more, particularly 9 or more, the gelation, precipitation, phase separation, and the like tend to occur depending on the kind of the fluorine resin fine particle aqueous dispersion to be used in mixing with the aqueous fluorine resin dispersion , It becomes difficult to obtain a homogeneous mixed dispersion.

In addition to the pH of the aluminum oxide fine particle sol used for the combination of the fluorine resin-aluminum oxide mixed dispersion, the pH of the aqueous fluorine resin fine particle dispersion also has a great influence.

This is because the pH of the mixed solution produced by mixing the aluminum oxide fine particle sol and the fluorine based resin fine particle aqueous dispersion is changed, and depending on the aluminum oxide fine particle sol used, the precipitation of aluminum hydroxide is caused by the pH change.

Therefore, the pH of the fluorine-based resin fine particle aqueous dispersion to be used in combination with the fluorine-based resin-aluminum oxide mixed dispersion is preferably 3.3 to 10.2, and more preferably 3.5 to 10.0.

As described above, addition of a surfactant is often very effective for stabilizing the suspended dispersion state of fine particles.

The surfactant to be used is selected in consideration of the affinity of the aluminum oxide and the fluororesin with the fine particles and the solvent, the electrostatic repulsion property of the generated complex micelles, etc. By simple mixing of the fluororesin fine resin aqueous dispersion and the aluminum oxide fine particle dispersion, The surfactant is not an essential component.

However, the addition of an appropriate amount of a suitable surfactant often increases the period during which the dispersion state is stably maintained. Therefore, the present invention is not limited to the addition of a surfactant, but rather may include a surfactant It is recommended to add a nonionic surfactant such as polyoxyalkylene alkyl ether or polyoxyalkylene alkyl phenyl ether.

When a surfactant is present in the fluorine resin-aluminum oxide mixed dispersion, it is natural that the surfactant may be added to the aluminum oxide fine particle and / or the fluorine resin fine particle through van der Waals interaction or electrostatic interaction, To thereby maintain a uniform dispersion state.

Therefore, instead of the surfactant, the surface of the aluminum oxide fine particles and / or the fluoric resin fine particles may be previously modified with a substance having a similar action, or a modification agent having such a function may be used as the aluminum oxide fine particles and / It is also effective to maintain the uniform dispersion state of the fluorine resin-aluminum oxide mixed dispersion for a long period of time by adding it to each dispersion.

Specifically, the surface of the aluminum oxide fine particles may be modified with any kind of silane coupling agent or the like, or the silane coupling agent may be added to the aluminum oxide fine particle sol.

Naturally, aggregation of particulates is closely related to its concentration. When the concentration is increased, the viscosity is increased to cause coagulation and gelation, and cohesive precipitation tends to occur.

Therefore, in order to attain a uniform mixed dispersion state of the fluorine-based resin fine particles and the aqueous aluminum oxide fine particles and to maintain them for a long period of time, it is effective to lower the liquid concentration of the both fine particles, that is, the low particle concentration.

However, when the particle concentration is low, the film obtained by the application such as coating or impregnation is not only thin, but consumes a great deal of energy for evaporation of the solvent in the heat treatment step such as drying and firing, It is preferable that the concentration is high. From this point of view, it is preferable that the weight ratio of the fluoric resin fine particles to the content of Al ₂ O _{3 which} is the hydroxyl group-containing aluminum oxide fine particles in the liquid is 3 to 100 and the weight ratio of water is 10 to 120 Do.

&Lt; Method of producing fluorinated resin-aluminum oxide mixed dispersion >

The fluorinated resin-aluminum oxide mixed dispersion of the present invention is prepared by mixing an aqueous dispersion of fluoric resin fine particles and an aluminum oxide fine particle suspension under stirring, wherein the pH of the aluminum oxide fine particle dispersion is preferably in the range of 2.5 to 7.0.

The lower limit of the range of the weight ratio of the fluoric resin fine particles to the content of Al ₂ O _{3 as} the alumina fine particles in the mixed liquid is preferably 3.1, more preferably 3.2, and the upper limit is preferably 100 and more preferably 54.0.

The lower limit of the weight ratio of water to the content of Al ₂ O _{3 as} the alumina fine particles in the mixed solution is preferably 10, more preferably 15.0, and the upper limit is preferably 120, more preferably 51.0.

Stirring at the time of mixing is not particularly specified. The optimum stirring conditions are appropriately selected in consideration of the particle concentration at the time of mixing, the viscosity of the mixed liquid, the liquid temperature, and the like. The temperature at the time of stirring is usually room temperature, but there is no problem in raising or lowering the temperature from the room temperature in consideration of the viscosity of the mixed solution or the like, and the stirring temperature is appropriately selected depending on the situation. The pressure at the time of mixing and stirring is not particularly specified, and is usually carried out under atmospheric pressure. However, when pressurization or depressurization is required from the viewpoint of the viscosity or concentration of the solvent, the pressure can be selected according to the purpose.

<About raw materials>

In completing the present invention, the aqueous dispersion or emulsion of the fluoric resin microparticles actually used in the examples and the comparative examples and the colloidal sol of the metal oxide fine particles are as follows. In the specification, A-1 to A-3, B-1 Attach the symbols of ~ B-9.

Fluorine-based resin fine particle aqueous dispersion

A-1: Polyfun D-111 (PTFE solid content: 60% by weight, average molecular weight: 2 x 10 ⁴ to 1 x 10 ⁷ , particle size: 0.25 m, pH: 9.7)

A-2: Asahi glass product, AD911E (PTFE solid content: 60% by weight, average molecular weight: 2 x 10 ⁴ to 1 x 10 ⁷ , particle size:

A-3: 31-JR (PTFE solid content: 60% by weight, average molecular weight: 2 x 10 ⁴ to 1 x 10 ⁷ , particle size: 0.25 m, pH: 10.5)

The particle size refers to the average particle diameter of the PTFE primary particles.

Aluminum oxide fine particle sol

B-1: Alumina sol-10A (weight% in terms of Al ₂ O ₃ : 9.8 to 10.2, particle size nm: 5-15, viscosity 25 ° C, mPa / s: 4.2)

B-2: Alumina sol-A2 (weight% in terms of Al ₂ O ₃ : 9.8 to 10.2, particle size nm: 10-20, viscosity 25 ° C, mPa / s: 4.2)

B-3: alumina sol -CSA-110AD (weight% in terms of Al ₂ O ₃ : 6.0 to 6.4, particle size nm: 5-15, viscosity 25 ° C, mPa / s: <50, pH: 3.8-4.5)

B-4: Alumina sol-F1000 (weight% in terms of Al ₂ O ₃ : 4.8 to 5.2, particle size nm: 1400, viscosity 25 ° C, mPa / s: <1000, pH: 2.9-3.3)

B-5: Alumina sol-F3000 (weight% in terms of Al ₂ O ₃ : 4.8 to 5.2, particle size nm: 2000-4500, viscosity 25 ° C, mPa / s: 3.3)

B-6: Nissan Chemical product, AS200 (weight% in terms of Al ₂ O ₃ : 10.5, particle size nm: unspecified, pH: 4.7)

B-7: Taki Chemical, bar chiral Al-L7 (Al ₂ O ₃ Weight%: 7, particle size nm: 5-10, pH: 8)

B-8: Taki Chemical, bar chiral Al-M15 (Al ₂ O ₃ Weight%: 15, particle size nm: 30, pH: 7-9)

B-9: Alumina sol-5N (weight% in terms of Al ₂ O ₃ : 5.0, particle size nm: 20, viscosity 25 ° C, mPa / s: 3.5, pH: 6.5)

The particle size refers to the particle diameter range measured by each aluminum oxide fine particle sol.

[Example]

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. Various examples and comparative examples are described below, and a table summarizing the results is shown below.

<Effects of raw materials>

As the examples, the kinds of the fluorine-based resin fine particle aqueous dispersion and the aluminum oxide fine particle sol were variously changed.

(Example 1)

A fluorine-based resin fine particle aqueous dispersion; A-1: 300 g

Aluminum oxide fine particle sol; B-2: 150 g

Mixing temperature: room temperature

Stirring time: 60 minutes

Results: Teflon (registered trademark) resin fine particles-alumina boehmite fine particles A mixed dispersion of a fluororesin-alumina having a solid content of 43% by mass was prepared. This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 180 days. In addition, the viscosity was not changed almost before and after the combination, and the fluidity was very good, and there was no problem even after 200 days of use as a coating liquid for fluorine resin coating or impregnation liquid.

(Example 2)

A fluorine-based resin fine particle aqueous dispersion; A-1: 30 g

Aluminum oxide fine particle sol; B-3: 20 g

Mixing temperature: room temperature

Stirring time: 30 minutes

Results: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 28 days. In addition, the viscosity thereof hardly changed before and after the combination, and the fluidity was extremely good, and there was no problem even after 30 days of use as the coating liquid for fluorine resin coating or impregnation liquid.

(Example 3)

A fluorine-based resin fine particle aqueous dispersion; A-2: 30 g

Aluminum oxide fine particle sol; B-2: 20 g

Mixing temperature: room temperature

Stirring time: 30 minutes

Results: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 28 days. In addition, the viscosity did not substantially change before and after the blending, and the fluidity was very good, and there was no problem even after 30 days of use as a coating liquid for impregnation with fluorine resin or impregnation liquid.

(Example 4)

A fluorine-based resin fine particle aqueous dispersion; A-1: 30 g

Aluminum oxide fine particle sol; B-4: 20 g

Mixing temperature: room temperature

Stirring time: 60 minutes

Results: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 14 days. However, the viscosity increased considerably after the combination, and the fluidity was considerably lowered with the lapse of time, but never completely disappeared. In addition, it was confirmed that the fluidity of the present mixed liquid remarkably improved, that is, recovered by vibration or shaking. Therefore, the present combination liquid was shaken before use, and there was no problem in using it as a coating liquid for fluorine resin coating or an impregnation liquid after 15 days.

(Example 5)

A fluorine-based resin fine particle aqueous dispersion; A-2: 30 g

Aluminum oxide fine particle sol; B-4: 20 g

Mixing temperature: room temperature

Stirring time: 60 minutes

Results: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 14 days. However, the viscosity increased considerably after the combination, and the flowability significantly decreased with time, but when the solution was stirred or shaken, its fluidity recovered. Thus, by stirring the present combination solution before use, there was no problem in using the coating solution for fluorine resin coating or the impregnation solution after 21 days.

(Example 6)

A fluorine-based resin fine particle aqueous dispersion; A-2: 42 g

Aluminum oxide fine particle sol; B-5: 42 g

Mixing temperature: room temperature

Stirring time: 50 minutes

Results: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 25 days. Further, although the viscosity increased after the combination, the fluidity was not lost, and there was no problem even after 25 days of use as a coating liquid for fluorine resin coating or impregnation liquid.

<Effect of mixture ratio>

As an example, the mixing ratio of the fluorine-based resin fine particle aqueous dispersion and the aluminum oxide fine particle sol was changed.

(Example 7)

A fluorine-based resin fine particle aqueous dispersion; A-2: 32 g

Aluminum oxide fine particle sol; B-4: 8 g

Mixing temperature: room temperature

Stirring time: 50 minutes

Result: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 5 days. In addition, although the viscosity increased after the combination, there was no problem with the fluidity and there was no problem in using the coating liquid for fluorine resin coating or the impregnation liquid.

(Example 8)

A fluorine-based resin fine particle aqueous dispersion; A-2: 32 g

Aluminum oxide fine particle sol; B-3: 8 g

Mixing temperature: room temperature

Stirring time: 40 minutes

Results: This solution did not cause coagulation gelation, aggregation precipitation, and phase separation for more than 4 days. In addition, although the viscosity increased after the combination, there was no problem with the fluidity and there was no problem in using the coating liquid for fluorine resin coating or the impregnation liquid.

(Example 9)

A fluorine-based resin fine particle aqueous dispersion; A-2: 24 g

Aluminum oxide fine particle sol; B-2: 16 g

Mixing temperature: room temperature

Stirring time: 30 minutes

Results: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 7 days. In addition, the viscosity of the composition did not substantially change before and after the combination, and the fluidity was very good, and there was no problem even after 14 days of use as a coating liquid for fluorine resin coating or impregnation liquid.

(Example 10)

A fluorine-based resin fine particle aqueous dispersion; A-1: 24 g

Aluminum oxide fine particle sol; B-3: 16 g

Mixing temperature: room temperature

Stirring time: 30 minutes

Results: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 14 days. In addition, the viscosity was not changed almost before and after the combination, and the fluidity was very good, and there was no problem even after 20 days for use as a coating liquid for fluorine resin coating or impregnation liquid.

(Example 11)

A fluorine-based resin fine particle aqueous dispersion; A-1: 24 g

Aluminum oxide fine particle sol; B-4: 16 g

Mixing temperature: room temperature

Stirring time: 40 minutes

Results: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 3 days. In addition, although the viscosity increased after the combination, there was no problem with the fluidity and there was no problem in using the coating liquid for fluorine resin coating or the impregnation liquid.

(Example 12)

A fluorine-based resin fine particle aqueous dispersion; A-1: 16 g

Aluminum oxide fine particle sol; B-3: 24 g

Mixing temperature: room temperature

Stirring time: 30 minutes

Results: This solution did not cause coagulation gelation, aggregation precipitation, and phase separation for more than 10 days. In addition, the viscosity of the composition did not substantially change before and after the combination, and the fluidity was very good, and there was no problem even after 15 days of use as a coating liquid for fluorine resin coating or impregnation liquid.

(Example 13)

A fluorine-based resin fine particle aqueous dispersion; A-1: 6 g

Aluminum oxide fine particle sol; B-3: 18 g

Mixing temperature: room temperature

Stirring time: 40 minutes

Results: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 15 days. In addition, the viscosity thereof hardly changed before and after the combination, and the fluidity was very good, and there was no problem in using it as a coating liquid for impregnation with fluorine resin or impregnation liquid.

(Example 14)

A fluorine-based resin fine particle aqueous dispersion; A-1: 36 g

Aluminum oxide fine particle sol; B-1: 4 g

Mixing temperature: room temperature

Stirring time: 40 minutes

Results: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 3 days. In addition, although the viscosity increased slightly after the combination, the fluidity was sufficient, and there was no problem in using it as a coating solution for impregnating a fluorine resin or an impregnation solution.

&Lt; Preparation of mixed dispersion using aqueous dispersion of fluoric resin fine particles in acidic pH range >

Acetic acid was added to the aqueous dispersion of the fluoric resin microparticles described below to adjust the pH of the aqueous fluoric resin microparticle dispersion to 3.5.

The aqueous dispersion of the fluorine-based resin fine particles adjusted to pH 3.5 and the aluminum oxide fine particle sol were mixed, stirred, and then allowed to stand to confirm the behavior of the mixed dispersion.

(Example 15)

A fluorine-based resin fine particle aqueous dispersion; A-1: 6 g

Aluminum oxide fine particle sol; B-1: 4 g

Mixing temperature: room temperature

Stirring time: 30 minutes

Result: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 5 days. In addition, the viscosity was not changed almost before and after the combination, and the fluidity was extremely good, and there was no problem even after 5 days of use as the coating liquid for fluorine resin coating or impregnation liquid. In addition, this solution has a pH of 3.6.

<Preparation of Mixed Dispersion Using Aluminum Oxide Fine Particle Sol of Neutral pH Region>

As an example, a mixed dispersion liquid was prepared by using the fluorine-based resin fine particle aqueous dispersion and the aluminum oxide fine particle sol having a neutral pH range. Further, the mixing ratio of the aqueous fluororesin microparticle dispersion and the aluminum oxide fine particle sol in the neutral pH region was changed.

(Example 16)

A fluorine-based resin fine particle aqueous dispersion; A-1: 8 g

Aluminum oxide fine particle sol; B-9: 2 g

Mixing temperature: room temperature

Stirring time: 30 minutes

Results: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 11 days. In addition, the viscosity thereof hardly changed before and after the combination, and the fluidity was extremely good, and there was no problem even after 11 days of use as a coating liquid for impregnation with fluorine resin or impregnation liquid.

(Example 17)

A fluorine-based resin fine particle aqueous dispersion; A-1: 6 g

Aluminum oxide fine particle sol; B-9: 4 g

Mixing temperature: room temperature

Stirring time: 30 minutes

Results: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 11 days. In addition, the viscosity thereof hardly changed before and after the combination, and the fluidity was extremely good, and there was no problem even after 11 days of use as a coating liquid for impregnation with fluorine resin or impregnation liquid.

(Example 18)

A fluorine-based resin fine particle aqueous dispersion; A-1: 4 g

Aluminum oxide fine particle sol; B-9: 6 g

Mixing temperature: room temperature

Stirring time: 30 minutes

Results: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 11 days. In addition, the viscosity thereof hardly changed before and after the combination, and the fluidity was extremely good, and there was no problem even after 11 days of use as a coating liquid for impregnation with fluorine resin or impregnation liquid.

(Example 19)

A fluorine-based resin fine particle aqueous dispersion; A-1: 2 g

Aluminum oxide fine particle sol; B-9: 8 g

Mixing temperature: room temperature

Stirring time: 30 minutes

Results: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 11 days. In addition, the viscosity thereof hardly changed before and after the combination, and the fluidity was extremely good, and there was no problem even after 11 days of use as a coating liquid for impregnation with fluorine resin or impregnation liquid. The solution was pH 9.03.

&Lt; Specification of pH Range of Mixed Dispersion >

Ammonia water was added to the mixed dispersion of Example 17 to adjust the pH to 10.2, and the behavior of the mixed dispersion was confirmed by standing.

(Example 20)

A fluorine-based resin fine particle aqueous dispersion; A-1: 6 g

Aluminum oxide fine particle sol; B-9: 4 g

Mixing temperature: room temperature

Stirring time: 30 minutes

Result: This solution did not cause coagulation gelation, aggregation precipitation and phase separation for more than 5 days. In addition, the viscosity was not changed almost before and after the blending, and the fluidity was very good, and there was no problem even after 5 days of use as the coating liquid for fluorine resin coating or impregnation liquid. In addition, this solution has a pH of 10.2.

<Comparative Example>

&Lt; Effect of kinds of aluminum oxide fine particle sol and its pH &

As a comparative example, the kind of aluminum oxide fine particle sol was changed to examine the effect of pH.

(Comparative Example 1)

A fluorine-based resin fine particle aqueous dispersion; A-1: 30 g

Aluminum oxide fine particle sol; B-6: 20 g

Mixing temperature: room temperature

Stirring time: 60 minutes

Results: Stirring was stopped and the solution was separated into two liquids.

(Comparative Example 2)

A fluorine-based resin fine particle aqueous dispersion; A-2: 30 g

Aluminum oxide fine particle sol; B-6: 20 g

Mixing temperature: room temperature

Stirring time: 60 minutes

Results: Stirring was stopped and the solution was separated into two liquids.

(Comparative Example 3)

A fluorine-based resin fine particle aqueous dispersion; A-1: 30 g

Aluminum oxide fine particle sol; B-7: 20 g

Mixing temperature: room temperature

Stirring time: 60 minutes

Results: Stirring was stopped and the solution was separated into two liquids.

(Comparative Example 4)

A fluorine-based resin fine particle aqueous dispersion; A-1: 30 g

Aluminum oxide fine particle sol; B-8: 20 g

Mixing temperature: room temperature

Stirring time: 60 minutes

Results: Stirring was stopped and the solution was separated into two liquids.

(Comparative Example 5)

A fluorine-based resin fine particle aqueous dispersion; A-2: 30 g

Aluminum oxide fine particle sol; B-7: 20 g

Mixing temperature: room temperature

Stirring time: 60 minutes

Results: Stirring was stopped and the solution was separated into two liquids.

(Comparative Example 6)

A fluorine-based resin fine particle aqueous dispersion; A-2: 30 g

Aluminum oxide fine particle sol; B-8: 20 g

Mixing temperature: room temperature

Stirring time: 60 minutes

Results: Stirring was stopped and the solution was separated into two liquids.

&Lt; Influence of kinds of fluoric resin microparticle dispersion and its pH >

As a comparative example, the kind of the fluorine-based resin fine particle aqueous dispersion was changed and the effect of pH was examined.

(Comparative Example 7)

A fluorine-based resin fine particle aqueous dispersion; A-3: 300 g

Aluminum oxide fine particle sol; B-1: 150 g

Mixing temperature: room temperature

Stirring time: 60 minutes

Results: Stirring was stopped and the solution was separated into two liquids.

(Comparative Example 8)

A fluorine-based resin fine particle aqueous dispersion; A-3: 300 g

Aluminum oxide fine particle sol; B-3: 150 g

Mixing temperature: room temperature

Stirring time: 60 minutes

Results: Stirring was stopped and the solution was separated into two liquids.

(Comparative Example 9)

A fluorine-based resin fine particle aqueous dispersion; A-3: 300 g

Aluminum oxide fine particle sol; B-2: 150 g

Mixing temperature: room temperature

Stirring time: 60 minutes

Results: Stirring was stopped and the solution was separated into two liquids.

(Comparative Example 10)

A fluorine-based resin fine particle aqueous dispersion; A-3: 300 g

Aluminum oxide fine particle sol; B-4: 150 g

Mixing temperature: room temperature

Stirring time: 60 minutes

Results: Stirring was stopped and the solution was separated into two liquids.

<Effect of mixture ratio>

As a comparative example, the mixing ratio of the fluorine-based resin fine particle aqueous dispersion and the aluminum oxide fine particle sol was changed.

(Comparative Example 11)

A fluorine-based resin fine particle aqueous dispersion; A-1: 8 g

Aluminum oxide fine particle sol; B-2: 32 g

Mixing temperature: room temperature

Result: Upon mixing at room temperature, the mixture was gelled and solidified.

(Comparative Example 12)

A fluorine-based resin fine particle aqueous dispersion; A-1: 8 g

Aluminum oxide fine particle sol; B-4: 32 g

Mixing temperature: room temperature

Stirring time: 60 minutes

Results: Stirring was stopped and the solution was separated into two liquids.

(Comparative Example 13)

A fluorine-based resin fine particle aqueous dispersion; A-2: 8 g

Aluminum oxide fine particle sol; B-3: 32 g

Mixing temperature: room temperature

Stirring time: 40 minutes

Results: Stirring was stopped and the solution was separated into two liquids.

(Comparative Example 14)

A fluorine-based resin fine particle aqueous dispersion; A-2: 8 g

Aluminum oxide fine particle sol; B-2: 32 g

Mixing temperature: room temperature

Stirring time: 40 minutes

Results: Stirring was stopped and the solution was separated into two liquids.

The results of the examples are shown in Tables 1 to 3, and the results of the comparative examples are shown in Tables 4 and 5.

The table of the Al ₂ O ₃ aluminum oxide fine particles sol in terms of% by weight is has recorded the median value of the Al ₂ O ₃ in terms of% by weight of each of aluminum oxide fine particles sol.

In the table, the weight ratio of the fluorine resin to Al ₂ O ₃ was determined by the following formula. The median value of the range was used for the value of% by weight in terms of Al ₂ O ₃ .

· (A fluorine-based resin fine particles aqueous dispersion of PTFE mixed amount × solid content wt% / 100) ÷ (the mixing amount of the aluminum oxide fine particles sol Al ₂ O ₃ in terms of weight% × / 100)

The weight ratio of water to Al ₂ O ₃ was determined by the following formula.

(Mixing amount of the fluorine-based resin fine particle aqueous dispersion x (100-PTFE solid content wt%) / 100)} + {amount of aluminum oxide fine particle sol mixed x 100 (% by weight in terms of Al ₂ O ₃ ) / 100 mixing amount of the aluminum oxide fine particles sol Al ₂ O ₃ in terms of weight% × / 100)

In addition, after the stirring, the dispersion state was stably maintained for 3 days or more was recorded as OK in the result column of each table, and NG was recorded as being not stably maintained for 3 days or more.

EFFECTS OF THE INVENTION [

Fig. 1 (a) shows a gas chromatograph mass spectrometry of a fluorine resin powder obtained by evaporating, drying and drying an aqueous fluorine resin fine particle dispersion, and Fig. 1 (b) shows a fluorine resin- The mass spectrometry analysis of the mixed powder of the fluorine-based resin and alumina obtained by evaporating, drying, and drying the dispersion was carried out.

As can be seen from the examples, it has been found that the aluminum oxide mixed with the fluorine-based resin is effective for improving the heat resistance of the fluorine-based resin, suppressing heat deterioration and suppressing generation of decomposed gas. That is, as shown in FIG. 1, mixed particle powders of a fluorine-based resin and alumina obtained by evaporating, drying and drying the fluorine-based resin-aluminum oxide mixed dispersion of the present invention and fluorine-based resin fine particles obtained by completely performing the same operations from the aqueous fluorine- As a result of performing gas chromatography mass spectrometry while heating and raising the temperature of each of the resin powders as the samples under the same conditions, the initial decomposition peak appeared at 330 DEG C in the former (Fig. 1 (b)), (a)) at 240 &lt; 0 &gt; C. Therefore, the addition of alumina has been demonstrated for the first time by the present invention, which is effective for improving the heat resistance of the fluorine resin solids, suppressing heat deterioration and suppressing generation of decomposed gas.

In the gas chromatograph mass spectrometry, heating and heating were carried out up to 750 ° C. As a result, as shown in FIG. 2, the ash (residue) containing a large amount of fluorine and aluminum was obtained from the former. Almost never. This is because almost all of the fluorine resin fine particles are decomposed and scattered by the heating temperature rise to 750 DEG C in the dispersion or powder of only the fluorine resin fine particles not containing the aluminum oxide fine particles and the fluorine resin-aluminum oxide mixed dispersion and the In the mixed fine particle powder, the aluminum oxide fine particles interact with the fluorine of the fluorine resin fine particles to suppress the scattering thereof. That is, it shows that alumina is effective for trapping and supplementing fluorine. At the same time, it is presumed that alumina (that is, aluminum) is uniformly dispersed and distributed in the mixed powder body due to the interaction of the fluorine-aluminum oxide fine particles with the solid obtained by drying and heating from the fluorine resin-aluminum oxide mixed dispersion.

Since aluminum compounds including alumina are Lewis acids of electron shortage type and fluorine is a Lewis base with an excess of electron pairs, fluorine-aluminum oxide fine particle interactions are theoretically reasonable. On the other hand, in the above-described Patent Document 2, since the metal oxide is silica and the silica is not an electron shortage type Lewis acid, unlike alumina, strong interaction with fluorine can not be expected. For this reason, it is considered that the silica migrates during drying to cause aggregation and become ubiquitous.

The above-mentioned estimation is actually valid from the observation of the SEM image of the mixed powder of the fluororesin-aluminum oxide. Fig. 3 shows an SEM image of the powder obtained by the evaporation drying of the fluorinated resin-alumina oxide mixed dispersion of Example 4.

That is, as can be seen from Fig. 3, the same as the silica mass in the SEM image of Patent Document 2 is not confirmed at all in this SEM image, and the surface of the powder body is the same everywhere. Therefore, it can be said that the alumina is uniformly dispersed and distributed in the mixed powder of the fluororesin-aluminum oxide obtained in the present invention. Thus, in the fluorine-based resin-aluminum oxide mixed dispersion of the present invention, the alumina particles are uniformly distributed evenly by simply performing ordinary simple drying and heating operations after the operations such as impregnation and coating without coagulating and sedimenting once, · Effectively demonstrate flame retardant effect.

Fig. 4 shows typical examples of uniform suspension dispersion, phase separation and gelation obtained by mixing the fluoric resin fine particle dispersion with alumina sol in the above-mentioned examples and comparative examples. The superior and superiority of the homogeneous suspension- And its utility as a coating solution and an impregnation solution.

&Lt; Application and efficacy of the present invention >

Based fluorine resin alone coated graphite gasket and a fluorine resin alone coated SUS gasket were prepared by applying the fluorine resin-alumina mixed dispersion and the fluorine resin-only dispersion to each of the existing expanded graphite and SUS gasket substrates, . Was tested through a gasket tester from Amtec, Germany.

The gasket containing no alumina and having a fluorine-based resin alone coating gas leaked for 3 hours under the pressure of 10 bar at 250 DEG C irrespective of the expanded graphite substrate and the SUS substrate, whereas the gasket made of the fluorine- The gas leakage was not detected at all under 10 hours of use under the same temperature and pressure.

The fluorine-based resin-aluminum oxide mixed dispersion of the present invention can be applied to various surfaces of various materials such as metal, carbon, plastic, glass, ceramic, graphite, carbon fiber and carbon fiber and coating liquid for coating the surfaces of products made of these materials, It is preferably used as an impregnating liquid for powders. Specifically, it is used as a coating or coating material for covering various materials and products such as electric wires, thermometers, various sensors, gaskets and packing.

Claims (9)

Based resin fine particles and aluminum oxide fine particles are suspendively dispersed together as an aqueous dispersion obtained by mixing an aqueous dispersion of fluorine-based resin fine particles and an aluminum oxide fine particle suspension to stably maintain the main dispersion state for 3 days or more. Aluminum oxide mixed dispersion. The method according to claim 1,
Wherein the solid obtained by evaporating the solvent from the fluorine-based resin-aluminum oxide mixed dispersion has a heat resistance of 330 ° C or higher. 3. The method according to claim 1 or 2,
Wherein the aluminum oxide is uniformly distributed and dispersed in the solid material obtained by evaporating the solvent from the fluorine resin-aluminum oxide mixed dispersion liquid. 4. The method according to any one of claims 1 to 3,
Wherein the pH of the aqueous dispersion of the fluorine-based resin fine particles is 3.5 to 10.2 and the fluorine-based resin fine particles are tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, perfluoro (alkyl vinyl ether), vinylidene fluoride And a fluorine-based resin-aluminum oxide mixed dispersion which is a resin fine particle made of a polymer or copolymer of a monomer selected from vinyl fluoride. 5. The method according to any one of claims 1 to 4,
Wherein the aluminum oxide fine particles in the aluminum oxide fine particle sol are aluminum oxide fine particles having an oxo (OH) group. 6. The method of claim 5,
Wherein the pH of the hydroxyl group-containing aluminum oxide fine particle sol is from 2.5 to 7.0 and the hydroxyl group-containing aluminum oxide fine particles in the sol are boehmite or diaspore (composition formula: AlOOH) and the particle size of the fluorine resin- Dispersion. The method according to claim 5 or 6,
Wherein the weight ratio of fluoric resin fine particles to the content of Al ₂ O _{3 as} the hydroxyl group-containing aluminum oxide fine particles in the liquid is in the range of 3.1 to 100 and the weight ratio of water is 10 to 120 in the fluororesin-aluminum oxide mixed dispersion, Oxide mixed dispersion. 8. The method according to any one of claims 1 to 7,
A fluorine-based resin-aluminum oxide mixed dispersion having a pH of 3.5 to 10.2. an aqueous dispersion of fluorine-based resin fine particles having a pH of 3.5 to 10.2 and a hydroxyl group-containing aluminum oxide fine particle sol having a pH of 2.5 to 7.0 were added to the content of Al ₂ O ₃ as alumina fine particles in the liquid at a temperature ranging from 5 to 100 ° C Wherein the weight ratio of the fluorine-based resin fine particles to the fluorine-based resin fine particles is from 3.1 to 100 and the weight ratio of water is from 10 to 120. The method for producing a fluorine-based resin-

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