JP7078441B2 - Polytetrafluoroethylene aqueous dispersion - Google Patents

Description

The present invention stably disperses polytetrafluoroethylene (PTFE) particles over a long period of time, is excellent in handling, and has features unique to PTFE, such as water repellency, oil repellency, electrical characteristics, heat resistance, electrical insulation, and low. The present invention relates to a polytetrafluoroethylene aqueous dispersion capable of imparting dielectric properties, low friction properties, non-adhesiveness, weather resistance, flame retardancy, etc., and a polytetrafluoroethylene function-imparting aqueous composition using the same.

Polytetrafluoroethylene (hereinafter, may be simply referred to as "PTFE") has water repellency, oil repellency, electrical properties, heat resistance, electrical insulation, low dielectric properties, low friction properties, non-adhesiveness, weather resistance, and difficulty. It is a material with excellent flammability and is used in electronic devices, sliding materials, automobiles, kitchen supplies, etc.
Polytetrafluoroethylene having such characteristics is used as a micropowder for the purpose of improving product characteristics by being added to various resin materials, rubbers, adhesives, lubricants and greases, printing inks and paints. There is.

For example, polytetrafluoroethylene micropowder (PTFE particles) is usually a tetrafluoroethylene (TFE) monomer by an emulsion polymerization method in the presence of stabilizers such as water, a polymerization initiator, a fluorine-containing emulsifier, and paraffin wax. Is obtained as an aqueous dispersion containing PTFE particles by polymerizing the above-mentioned material, and then concentrated, aggregated, dried, and the like (see, for example, Patent Document 1).

Usually, in order to blend PTFE particles with a liquid material such as a paint and impart the functions of PTFE, it is necessary to disperse the PTFE particles in the liquid material. However, since it is not easy to wet the PTFE particles to the liquid material again, it is generally blended into the liquid material in the form of an aqueous dispersion to which a stabilizer is added after polymerization.
In this conventional PTFE aqueous dispersion, the particles are easily fibrilized, so that the particles aggregate with each other by a slight shearing. In addition, since the dispersion state at the time of emulsion polymerization is inherited, the dispersion stability is poor, and there is a problem that a hard cake is formed in the container over time.

Conventionally, as a means for solving these problems, for example,
1) PTFE particles having an average particle size of 0.1 to 0.5 μm obtained by emulsification polymerization are 5% by mass or more and less than 30% by mass, and a nonionic surfactant having a specific structure is 1 to 1 to 2 with respect to PTFE. A polytetrafluoroethylene aqueous dispersion (see, for example, Patent Document 2), which contains 12% by mass and 1 to 10% by mass of polyethylene oxide having an average molecular weight of 100,000 to 2 million with respect to PTFE.
2) Contains 10 to 70% by mass of fine particles of polytetrafluoroethylene having an average particle size of 0.1 to 0.5 μm and an average molecular weight of 700,000 to 30 million, and a pH of 6.0 to 13.0. A method for producing a low molecular weight polytetrafluoroethylene aqueous dispersion, which comprises irradiating the polytetrafluoroethylene aqueous dispersion with γ-rays at 2 to 100 kGy (see, for example, Patent Document 3).
3) 30 to 65% by weight of the polytetrafluoroethylene fine particles obtained by emulsion polymerization, at least one selected from nonionic surfactants having an average molecular structure represented by the specific formulas (1) and (2). 2 to 12% by weight based on polytetrafluoroethylene, and 0.01% by weight or more and less than 1% by weight based on polytetrafluoroethylene containing polyethylene oxide having an average molecular weight of 100,000 to 2 million as essential components. A polytetrafluoroethylene aqueous dispersion composition (see, for example, Patent Document 4) characterized by the above is known.

However, since the dispersion stability of the PTFE aqueous dispersion described in Patent Documents 2 to 4 is derived from the dispersed state at the time of emulsion polymerization, it needs to be stirred for long-term precipitation and redispersion. There is a problem. Further, in the case of blending 0 with a liquid material such as a paint, PTFE is separated in the final product, which greatly imposes design restrictions and is inferior in versatility.
Further, in order to eliminate sedimentation, it is conceivable to enhance the dispersion stability by mechanical dispersion treatment, but the PTFE aqueous dispersion described in Patent Documents 2 to 4 above suppresses fibrillation due to rubbing or the like. However, it is insufficient to suppress fibrillation by mechanical dispersion treatment, and the current situation is that dispersion stability cannot be enhanced by mechanical dispersion treatment.
Further, some of the low molecular weight PTFE fine particles generally used for additive applications can enhance the dispersion stability by mechanical dispersion treatment, but the PTFE fine particles are completely wetted with water. Since it is difficult to do so, the remaining air bubbles may expand due to heat during the mechanical dispersion treatment, and problems such as an increase in the pressure inside the apparatus may occur. In addition, when the remaining bubbles expand, the surface of the once wet PTFE fine particles dries, which rather deteriorates the dispersibility. There are issues such as difficulty.

Japanese Unexamined Patent Publication No. 2012-92323 (Claims, Examples, etc.) Japanese Unexamined Patent Publication No. 2006-169448 (Claims, Examples, etc.) Japanese Unexamined Patent Publication No. 2006-63140 (Claims, Examples, etc.) Japanese Unexamined Patent Publication No. 2000-198899 (Claims, Examples, etc.)

The present invention is intended to solve the above-mentioned conventional problems and the current situation, and has excellent long-term dispersion stability, and even if it is added to a liquid material such as a paint, PTFE can be contained inside the final product. It is an object of the present invention to provide a PTFE aqueous dispersion or the like which can realize the function of PTFE in a desired final form and has economically excellent productivity.

As a result of diligent studies on the above-mentioned conventional problems, the present inventors have obtained fine particles of polytetrafluoroethylene having a primary particle size of 0.03 to 0.3 μm and a number average molecular weight Mn of 10,000 to 30,000. By containing a specific amount, the dispersant is contained in the fine particles of polytetrafluoroethylene in a specific amount, the foam volume ratio is set to less than a specific value%, and the average particle size by the dynamic light scattering method is set to less than a specific value. They have found that the above-mentioned target polytetrafluoroethylene aqueous dispersion and the like can be obtained, and have completed the present invention.

That is, the polytetrafluoroethylene aqueous dispersion of the present invention contains 10 to 70 fine particles of polytetrafluoroethylene having a primary particle size of 0.03 to 0.3 μm and a number average molecular weight of Mn of 10,000 to 30,000. Contains 0.5 to 20% by mass of the dispersant with respect to the fine particles of polytetrafluoroethylene, the foam volume ratio is less than 10 vol%, and the average particle size by the dynamic light scattering method is less than 300 nm. It is characterized by being.
The pH of the aqueous dispersion of polytetrafluoroethylene is preferably 8 to 13.
Further, in the polytetrafluoroethylene aqueous dispersion, the cake ratio after standing at 25 ° C. for 3 months is preferably 40% or less, and the redispersion ratio at that time is preferably 95% or more.
In the polytetrafluoroethylene function-imparting aqueous composition of the present invention, the binder resin has a solid content ratio of 20 to 95% by mass, and the polytetrafluoroethylene aqueous dispersion having the above composition has a solid content ratio of 5 based on polytetrafluoroethylene. It is characterized by containing at least 80% by mass.
The liquid coating tool of the present invention is characterized by being filled with the polytetrafluoroethylene function-imparting aqueous composition having the above constitution.

According to the present invention, it has excellent long-term dispersion stability, PTFE does not separate inside the final product even when added to a liquid material such as a paint, and the function of PTFE can be imparted in a desired final form, which is economical. Also provided are a polytetrafluoroethylene aqueous dispersion having excellent productivity, a polytetrafluoroethylene function-imparting aqueous composition using the same, and a liquid coating tool.

Hereinafter, embodiments of the present invention will be described in detail.
The polytetrafluoroethylene aqueous dispersion of the present invention contains 10 to 70% by mass of fine particles of polytetrafluoroethylene having a primary particle size of 0.03 to 0.3 μm and a number average molecular weight Mn of 10,000 to 30,000. It contains 0.5 to 20% by mass of the dispersant with respect to the fine particles of polytetrafluoroethylene, the foam volume ratio is less than 10 vol%, and the average particle diameter by the dynamic light scattering method is less than 300 nm. It is characterized by that.

<PTFE fine particles>
In the present invention, the PTFE fine particles have a primary particle diameter of 0.03 to 0.3 μm and a number average molecular weight Mn of 10,000 to 30,000.
In the present invention, the "primary particle diameter" is the primary particle diameter as observed by SEM, and the "number average molecular weight Mn" is the number average molecular weight as determined by the DSC method.
The PTFE particles having the primary particle size and the number average molecular weight are obtained by the emulsification polymerization method. For example, the method described in the fluororesin handbook (edited by Takaomi Satokawa, Nikkan Kogyo Shimbun) can be used. It is possible to obtain PTFE fine particles having the above primary particle size and number average molecular weight. Further, it is also possible to use PTFE fine particles satisfying the above primary particle size range in which the number average molecular weight Mn is 10,000 to 30,000 by irradiating the PTFE particles having a high number average molecular weight Mn with radiation such as γ-rays. be.
In the present invention (including examples described later), the primary particle size by SEM (Scanning Electron Microscope) observation indicates the distance in the longitudinal direction of the PTFE fine particles which is the minimum constituent unit. This SEM observation was measured using S-4700 manufactured by Hitachi High-Technologies Corporation.

Further, the number average molecular weight Mn by the DSC method (Differential scanning calorimetry) is the heat of crystallization when the temperature is raised to 350 ° C. at a heating rate of 10 ° C./min and cooled at 10 ° C./min. It is calculated from the following formula.
Mn = 2.1 × 10 ¹⁰ × ΔHc- ^5.16
Mn: Number average molecular weight ΔHc: DSC crystallization heat (cal / g)
In the present invention (including examples described later), the DSC method was measured using Thermo plus EVO2 DSC8231 manufactured by Rigaku.

If the primary particle size of the PTFE fine particles is less than 0.03 μm, it is very difficult to secure dispersion stability, and the dispersion easily aggregates and settles. On the other hand, if it exceeds 0.3 μm, it does not settle in the long term. It becomes difficult to maintain the dispersed state.
Further, if the number average molecular weight Mn is less than 10,000, the cost of irradiating radiation such as γ-rays increases, which is uneconomical. It causes the formation of aggregates.

The content of the PTFE fine particles having these characteristics varies depending on the use of the PTFE aqueous dispersion, etc., but 10 to 70% by mass (hereinafter, "mass%") is referred to as "mass%" with respect to the total amount of the PTFE aqueous dispersion. % ”), preferably 25 to 65%.
If the content of the PTFE fine particles is less than 10%, it is uneconomical because the manufacturing cost such as dispersion treatment increases, while if it exceeds 70%, the viscosity becomes too high and it is difficult to manufacture. Is not preferable because it is inferior in usability.

The aqueous PTFE dispersion of the present invention contains a dispersant from the viewpoint of improving dispersibility and redispersibility, and improving the wettability of water with respect to PTFE.
The dispersant that can be used is not particularly limited as long as it can uniformly and stably disperse the PTFE fine particles, and various dispersants can be used.
Preferably, the dispersant used from the viewpoint of suppressing adverse effects such as aggregation due to interaction with other materials in producing the final product is preferably a nonionic type.
Preferred dispersants include acrylic copolymers, fluorine-based copolymers, polyester-based copolymers, acetylene-based copolymers, silicone-based copolymers, and the like. 184, 185, 190, 191, 192, 193, 194, 198, 199, 2010, 2012, 2013, 2015, 2055, 2060, 2061 , 4601, PA4550, 4560, PX4575, 4585, COATEX BR3, A122, 123K, P30, P90, DIC Megafuck F-251, 253, 281, 430, 477, 551, 552, 552, 554 , 555, 556, 557, 558, 559, 560, 561, 562, 563, 565, 568, 569, 570, 571, 574, 575, 576, R-40, R-40-LM, R-41, R -94, RS-56, RS-72-K, RS-75, RS-76-E, RS-76-NS, RS-78, RS-90, DS-21, Fluorogen 251 and 208M manufactured by Neos. , 212M, 215M, 250, 209F, 222F, 245F, 208G, 218GL, 240G, 212P, 220P, 228P, FTX-218, DFX-18, 710FL, 710FM, 710FS, 730FL, 730LM, 610FM, 683, 601AD, 601ADH2 , 602A, 650AC, 681, AGC Seimi Chemical's Fluorine S-242, 243, 420, 386, 611, 651, Polymer B16H, B20H, B30T, B30H, B30HH, B45M, B45H, B60T, B60H, B60HH, B75H, BX860, Polymer BL16, Eslek BL-1, BL-1H, BL-2, BL-2H, BL-5, BL-10, BL-S, BX-L, BM-1 manufactured by Sekisui Chemical Industry Co., Ltd. , BM-2, BM-5, BM-S, BH-3, BH-6, BH-S, BX-1, BX-5, KS-1, KS-3, KS-5, KS-10, Solusia BUTPAR B-72, B-74, B-76, B-79, B-90, B-98, Orfin D-10A, 10PG, E1004, E1010, E1020, E1030W, manufactured by Nissin Chemical Industry Co., Ltd. PD-0 01, 002W, 004, 005, EXP. 4001, 4200, 4123, 4300, WE-001, WE-002, WE-003, Evonik's TEGO Dispers 740W, 741W, 750W, 755W, 757W, 760W, 761W, 765W, NOF's Esleem AD- 3172M, 374M, 508E, 221P, 221J, DP-2, DJ-2, Marialim AKM-0531, AFB-1521, AAB-0851, SC-0505K, SC-1015F, SC-0708A, etc. can be used.

The content of these dispersants is 0.5 to 20%, preferably 0.5 to 20%, based on the PTFE fine particles.
It is desirable to set it to 1 to 10%.
If the content of this dispersant is less than 0.5%, the dispersibility and redispersibility cannot be improved, while if it exceeds 20%, the viscosity of the dispersion becomes high, so that it can be manufactured or used. It is disadvantageous in terms of. In addition, the final product produced by blending the PTFE dispersion contains a large amount of unnecessary components, which is not preferable.

The aqueous PTFE dispersion of the present invention preferably has a pH of 8 to 13, more preferably 8.5 to 11.5, from the viewpoint of storage stability and the like.
When the pH is less than 8, mold grows on the PTFE aqueous dispersion, and germs propagate and spoil, which causes extra cost such as refrigerated storage. It is possible to adjust to an acidic area where mold and germs do not grow, but since many industrial equipment uses stainless steel for the wetted part, extra costs are incurred, such as the need for lining treatment on the wetted part. Will let you. On the other hand, if the pH exceeds 13, the risk to the living body increases, and the use of the final product produced by blending the PTFE dispersion is limited.
The pH of this PTFE aqueous dispersion is adjusted by the components used, the content thereof, and the like, and is adjusted by using a pH adjuster as necessary.

Examples of the pH adjuster that can be used include those containing amines, metal ions such as sodium hydroxide, and the like. Examples of amines include primary amines such as monoethanolamine and aminomethylpropanol, secondary amines such as diethanolamine, dimethylamine, diethylamine, diisopropylamine and dicyclohexylamine, triethanolamine, tripropanolamine, triethylamine and tripropyl. At least one of tertiary amines such as amines, tributylamines, triamylamines, pyridines and N-methylmorpholins, and quaternary ammonium hydroxides of tetramethyl, tetraethyl, tetrapropyl, tetrabutyl, tetraamyl, tetrahexyl and benzyltrimethyl. Seeds are mentioned.
The content of these pH adjusters may be any amount as long as the pH of the PTFE aqueous dispersion is in the above-mentioned preferable range, and a suitable amount can be contained.

Water (ion-exchanged water, distilled water, purified water, pure water, ultrapure water, tap water, etc.) is used as the dispersion medium for the PTFE aqueous dispersion of the present invention, but from the viewpoint of further improving the storage stability. Preferably, it can contain an appropriate amount of a water-soluble solvent and, if necessary, at least one selected from an antiseptic, an antifungal agent or an antibacterial agent.

The PTFE aqueous dispersion of the present invention is dynamically dispersed and mixed by adding additives such as PTFE fine particles and a dispersant having the above characteristics using a disperser, a kneader, etc., and has a foam volume ratio of less than 10 vol%. It is prepared so that the average particle size by the light scattering method is less than 300 nm.
In the present invention, the "foam volume" refers to the foam volume under a vacuum of a liquid temperature of 20 ° C. and an absolute pressure of 0.003 MPa, and the foam volume ratio of the PTFE aqueous dispersion is less than 10 vol% with respect to the PTFE aqueous dispersion volume. It is necessary, and preferably 5 vol% or less. When the foam volume ratio is 10 vol% or more, the bubbles remaining in the dispersion inhibit the dispersion of the PTFE fine particles, cause the reaggregation of the PTFE fine particles, or treat with a disperser, a kneader, or the like. In the above, when the heat is generated, the bubbles swell and the pressure rises in the apparatus, which is not preferable. At least, it is necessary to keep the foam volume ratio less than 10 vol% through the steps from the pre-stage of dispersing the PTFE fine particles with a disperser or a kneader to filling the container, and even in the storage state after filling the container. It is preferable to keep the foam volume ratio at a low level. The foam volume ratio in the stored state is preferably less than 3 vol%.
In the present invention (including Examples described later), the calculation of the foam volume ratio can be obtained by the following.
The volume of the PTFE aqueous dispersion at 1 atm is Vn, and the volume of the PTFE aqueous dispersion having a liquid temperature of 20 ° C. combined with the expanded foam when the absolute pressure is reduced to 0.003 MPa in a vacuum vessel is Vv. If so, the foam volume Vb can be obtained by Vb = Vv-Vn, and in the present invention, the foam volume Vb under a vacuum of a liquid temperature of 20 ° C. and an absolute pressure of 0.003 MPa is the polytetrafluoroethylene aqueous dispersion volume. It is less than 10 vol% with respect to [0.1> (Vv-Vn) / Vn].

In the present invention, the foam volume ratio of the PTFE aqueous dispersion is less than 10 vol%, for example, it can be carried out by vacuum defoaming treatment, heat aging treatment or the like.
The vacuum defoaming treatment can be performed using a vacuum defoaming device such as a vacuum defoaming mixer. For example, a vacuum chamber is filled with a PTFE aqueous dispersion, and the pressure is reduced to an absolute pressure of 0.020 MPa while stirring. The desired foam volume ratio can be obtained by a process of returning to atmospheric pressure after 10 minutes.
Further, as the heat aging treatment, the PTFE aqueous dispersion is hermetically filled in a can or the like and left to stand in a heat insulating chamber at 40 to 50 ° C. for several days to remove air bubbles and reduce the foam volume ratio.
By each of these treatments, the foam volume ratio can be adjusted. It is preferable that these defoaming treatments are carried out before the treatment using a disperser, a kneader or the like.

Further, the PTFE particles in the PTFE aqueous dispersion of the present invention have an average particle diameter of less than 300 nm by a dynamic light scattering method, preferably 50 to 250 nm. If the average particle size is 300 nm or more, it is difficult to suppress sedimentation over time and it is also difficult to redisperse, which is not preferable.
In the present invention (including Examples described later), the measurement of the average particle size by the dynamic light scattering method is a value measured by using FPAR-1000 manufactured by Otsuka Electronics Co., Ltd.
In the present invention, in order to make the average particle size by the dynamic light scattering method less than 300 nm, for example, a dispersant and PTFE fine particles are mixed with purified water, and a disperser (Dynomill Multilab type manufactured by WAB, φ0) is used. The average particle size can be adjusted by continuing the treatment with 3 mm zirconia beads, a filling rate of 65%, and a peripheral speed of 10 m / s) until the desired average particle size is reached.

Further, preferably, from the viewpoint of further exerting the effect of the present invention, the PTFE aqueous dispersion of the present invention has a cake ratio of 40% or less after standing at 25 ° C. for 3 months, and the redispersion ratio at that time. Is preferably 95% or more.
In the present invention (including Examples described later), the cake ratio after standing at 25 ° C. for 3 months is when a cylindrical glass container is filled with a PTFE aqueous dispersion and allowed to stand at 25 ° C. for 3 months. The ratio of the cake height Hc to the liquid height Hl is defined as Hc, which is a value calculated by slowly tilting the container to remove liquids other than the cake and then measuring the formula: Hc / Hl × 100 (%).
Further, in the present invention (including Examples described later), the redispersion ratio refers to the redispersibility after standing at 25 ° C. for 3 months, and after standing at 25 ° C. for 3 months, the touch mixer manufactured by Yamato Scientific Co., Ltd. Press it vertically against MT-31 for 10 seconds to shake it, and turn it upside down once. After repeating this 3 times, the liquid content was collected from the upper part so as not to collect the cake, and the solid content (180 ° C., mass after 10 minutes / mass of the collected liquid content) was measured, and the obtained solid content was obtained. The value calculated as a percentage of the initial solid content [(mass at 180 ° C. after 10 minutes) / (mass of aqueous dispersion)] is used as the redispersion ratio.
In order to set the cake ratio to 40% or less and the redispersion ratio to 95% or more, the primary particle size is 0.03 to 0.3 μm and the number average molecular weight Mn is 10,000 to 30,000. The intermediate of the PTFE aqueous dispersion containing 10 to 70% of the PTFE fine particles and 0.5 to 20% of the dispersant with respect to the PTFE fine particles was subjected to the above defoaming treatment, and the disperser (WAB) was used. Dynomill multi-lab type, φ0.3 mm zirconia beads, filling rate 65%, peripheral speed 10 m / s), and by continuing the treatment until the desired dispersion state is achieved, PTFE with the above cake ratio and the above redispersion ratio. An aqueous dispersion can be obtained.

The PTFE aqueous dispersion of the present invention configured as described above contains 10 to 10 fine particles of polytetrafluoroethylene having a primary particle size of 0.03 to 0.3 μm and a number average molecular weight of Mn of 10,000 to 30,000. It contains 70%, 0.5 to 20% of the dispersant with respect to the fine particles of polytetrafluoroethylene, the foam volume ratio is less than 10 vol%, and the average particle diameter by the dynamic light scattering method is less than 300 nm. As a result, it has excellent long-term dispersion stability, PTFE does not separate inside the final product even when added to liquid materials such as paints, and the function of PTFE can be imparted in the desired final form, which is economically economical. An aqueous dispersion of polytetrafluoroethylene having excellent productivity can be obtained.
Since the PTFE aqueous dispersion of the present invention does not separate PTFE inside the final product and can impart the function of PTFE in a desired final form, it modifies ink, paint (varnish, paint, etc.), grease, and toner. It can be suitably used as a modifier, an agent for improving the slipperiness and wear resistance of molding materials such as engineering plastics such as polyimide, polyamide, polycarbonate, and polyphenylene sulfide, and an additive to a plating solution. In addition, as an additive for molding materials, for example, improvement of non-adhesiveness / sliding characteristics of rolls such as copies, texture of molded products such as dashboards of automobiles, home appliances, covers of electrical equipment, etc. Applications that improve slipperiness and wear resistance of mechanical parts that cause mechanical friction such as bearings, gears, cams, sliding materials, applications that improve oil repellency or water repellency of wax, etc. , A secondary battery such as a lithium cell, a hardness adjusting agent for an electrode binder of a fuel cell, a water repellent treatment agent for an electrode surface, and the like, which can be suitably used for each application.

In the polytetrafluoroethylene function-imparting aqueous composition of the present invention, the binder resin has a solid content ratio of 20 to 95%, and the polytetrafluoroethylene aqueous dispersion having the above composition has a solid content ratio of 5 to 5 to 5 based on the polytetrafluoroethylene standard. It is characterized by containing at least 80%.
As the binder resin that can be used, a suitable binder resin is selected depending on the application to secondary batteries such as ink, paint (varnish, paint, etc.), grease, toner, lithium battery, electrode binder of fuel cell, and the like. For example, at least one of an aqueous dispersion such as a vinyl resin, a thermoplastic resin, a curable resin, a thermoplastic block copolymer and an elastomer can be mentioned.
Examples of the vinyl resin include aqueous dispersions of vinyl acetate resin, acrylic resin, styrene resin and the like. Examples of the thermoplastic resin include aqueous dispersions such as polyolefin resins, ethylene-vinyl acetate copolymers and polyamide resins. Examples of the curable resin include water dispersions such as epoxy resin, urethane resin, polyimide resin and unsaturated polyester resin. The curable resin may be a room temperature curable resin, a thermosetting resin, or a photocurable resin. Examples of the thermoplastic block copolymer include a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a hydrogenated additive of a styrene-butadiene-styrene block copolymer, and a styrene-isoprene. -Examples include an aqueous dispersion such as a hydrogenated additive of a styrene block copolymer. Examples of the elastomer include aqueous dispersions such as styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

The polytetrafluoroethylene aqueous dispersion used contains 10 to 70 fine particles of polytetrafluoroethylene having the above-mentioned structure, having a primary particle size of 0.03 to 0.3 μm and a number average molecular weight Mn of 10,000 to 30,000. %, The dispersant is contained in 0.5 to 20% with respect to the fine particles of polytetrafluoroethylene, the foam volume ratio is less than 10 vol%, and the average particle diameter by the dynamic light scattering method is less than 300 nm. It is a tetrafluoroethylene aqueous dispersion, preferably having a pH of 8 to 13, and / or having a cake ratio of 40% or less after standing at 25 ° C. for 3 months, and the redispersion ratio at that time is 40% or less. It is desirable that the content is 95% or more.

The polytetrafluoroethylene function-imparting aqueous composition of the present invention is, for example, a colorant, an antioxidant, a heat, in addition to the binder resin and the polytetrafluoroethylene aqueous dispersion, as long as the effects of the present invention are not impaired. Various additives such as stabilizers, light stabilizers, ultraviolet absorbers, lubricants, and antistatic agents may be contained in appropriate amounts.
The content of the binder resin is 20 to 95%, preferably 30 to 95%, as a solid content ratio with respect to the total solid content in the aqueous composition imparting the PTFE function, from the viewpoints of film forming property, stickiness and the like. It is preferably 90%.
Further, the content of the PTFE aqueous dispersion having the above constitution is 5 to 80%, preferably 5 to 80%, as a solid content ratio with respect to the total amount of the PTFE function-imparting aqueous composition from the viewpoint of expressing the PTFE function, stickiness and the like. It is preferably 10 to 60%.

The polytetrafluoroethylene function-imparting aqueous composition of the present invention thus constructed has excellent dispersion stability even with respect to a binder resin, and PTFE is present inside final products such as inks and paints (varnish, paint, etc.). Without separation, in the desired final form of each application, PTFE's water repellency, oil repellency, electrical properties, heat resistance, electrical insulation, low dielectric properties, low friction properties, non-adhesiveness, weather resistance, flame retardancy, etc. It is possible to obtain a polytetrafluoroethylene function-imparting aqueous composition having various functions to be imparted according to the purpose and having economically excellent productivity.

The liquid coating tool of the present invention is characterized by being filled with the polytetrafluoroethylene function-imparting aqueous composition having the above constitution.
As the liquid coating tool that can be used, 1) the polytetrafluoroethylene function-imparting aqueous composition having the above-mentioned constitution is filled, and the polytetrafluoroethylene function-imparting aqueous composition is targeted by the coating portion (coating body) provided in the front. It is not particularly limited as long as it can be applied to an object, and for example, a shaft cylinder filled with a polytetrafluoroethylene function-imparting aqueous composition, a coating portion provided at the tip of the shaft cylinder as a coating member, and the above. A liquid having at least a valve mechanism provided between the shaft cylinder and the coating portion, and having a structure in which the polytetrafluoroethylene function-imparting aqueous composition in the shaft cylinder is supplied to the coating portion by pressing the coating portion. A coating tool or 2) a polytetrafluoroethylene function-imparting aqueous composition having a predetermined coating portion provided at the tip and filled inside the main body portion as a shaft cylinder is pressed forward by a liquid pressing mechanism attached to the main body portion. 3) A liquid coating tool to be supplied to the coating portion, and a polytetrafluoroethylene function-imparting aqueous composition filled in the main body portion to be a shaft cylinder with a predetermined coating portion provided at the tip of the coating portion. Examples thereof include a liquid coating tool provided with a relay member for supplying to the coating portion by a capillary force between the cylinders.
Since the liquid coating tool of the present invention is filled with the polytetrafluoroethylene function-imparting aqueous composition having the above-mentioned constitution, it is easy and easy to apply the polytetrafluoroethylene uniformly to the object to be coated for each application without blurring or unevenness. A water-based composition imparting a fluoroethylene function can be applied.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. The present invention is not limited to the following examples and the like.

[Examples 1 to 3 and Comparative Examples 1 to 7: Preparation of PTFE aqueous dispersion]
In the formulation (PTFE particles, dispersant, pH adjuster, water) shown in Table 1 below, using a disperser: Dyno-Mill Multilab type, dispersion conditions: zirconia beads φ0.01 mm, filling rate 50%, circumference After 1 hour of batch treatment at a speed of 10 m / s, the beads were separated and the PTFE aqueous dispersion was recovered.
Next, in the case of vacuum defoaming treatment (notation "Yes" in Table 1), an example obtained in a vacuum chamber using a vacuum defoaming device (small vacuum defoaming mixer manufactured by Mixta Industries, Ltd.). , Each PTFE aqueous dispersion of Comparative Example was filled, the pressure was reduced to an absolute pressure of 0.020 MPa with stirring, and the pressure was returned to atmospheric pressure after 10 minutes.

For each of the obtained PTFE aqueous dispersions, the foam volume ratio and the average particle size were measured by the above-mentioned measuring method, and the pH was measured by the following method.
(PH measurement method)
Each of the obtained PTFE aqueous dispersions (25 ° C.) was measured using a pH meter (F-72, manufactured by HORIBA).
Further, for each of the obtained PTFE aqueous dispersions, the static cake ratio (%) and the redispersion ratio after the lapse of 3 months at 25 ° C. were measured by the above-mentioned methods.
The results of these measurements and evaluations are shown in Table 1 below.

(Evaluation of PTFE function-imparting aqueous composition)
Further, the obtained PTFE aqueous dispersions of Examples 1 to 3 and Comparative Examples 1 to 7 were added to 50% by mass based on the solid content, and the binder resin 1 (acrylic resin, Neocryl XK-190, manufactured by Kusumoto Kasei Co., Ltd., solid). (45% by mass) or binder resin 2 (urethane resin, Superflex 150, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., solid content 30% by mass) is mixed with 50% by mass in a beaker based on the solid content and stirred by hand. Then, the PTFE function-imparting aqueous compositions 1 and 2 corresponding to Examples 1 to 3 and Comparative Examples 1 to 7 were prepared.
The obtained PTFE function-imparting aqueous compositions 1 and 2 were evaluated for dispersion stability by the following evaluation method. The results of these evaluations are shown in Table 1 below.

(Evaluation method of dispersion stability)
Each of the obtained PTFE function-imparting compositions was visually evaluated for dispersibility at 40 ° C. after 1 week according to the following evaluation criteria.
Evaluation criteria:
◯: Good △: Slightly aggregated / settled ×: Completely aggregated or settled

(Evaluation of applicability with liquid applicator)
Aqueous composition 1 that imparts a PTFE function to a container of a liquid coating tool (PC-17K, coating part: felt fiber coating body, shaft material: PP resin, size: shaft diameter φ28.0 x total length 157.0 mm) manufactured by Mitsubishi Pencil Co., Ltd. Was filled and applied to an acrylic resin plate (100 × 100 × 5 mm), and the applicability was functionally evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1 below.
Evaluation criteria:
○: Good △: Slightly blurred or uneven ×: Completely blurred or uneven

As is clear from the results in Table 1 above, Examples 1 to 3 according to the present invention are superior in long-term dispersion stability as compared with Comparative Examples 1 to 7 which are outside the scope of the present invention, and are used for coating materials and the like. It has been confirmed that even if it is added to a liquid material, PTFE does not separate inside the final product, the function of PTFE can be imparted in a desired final form, and the aqueous dispersion of PTFE has excellent productivity economically. rice field.
Further, it was confirmed that the PTFE function-imparting aqueous composition using the PTFE aqueous dispersions of Examples 1 to 3 and the liquid applicator filled with the same were excellent in dispersion stability and applicability.

The PTFE aqueous dispersion of the present invention has excellent long-term dispersion stability, and even if it is added to a liquid material such as a paint, PTFE does not separate inside the final product, and it is possible to realize the function of PTFE in a desired final form. Molding materials such as inks, paints (varnishes, paints, etc.), greases, modifiers that modify toners, engineering plastics such as polyimides, polyamides, polycarbonates, and polyphenylene sulfides, as they have excellent productivity economically. It can be suitably used as an agent for improving the slipperiness and abrasion resistance of the material, an additive to the plating solution, and the like.

Claims (5)

It contains 25 to 65 % by mass of fine particles of polytetrafluoroethylene having a primary particle size of 0.03 to 0.3 μm and a number average molecular weight Mn of 10,000 to 30,000, and the dispersant is fine particles of polytetrafluoroethylene. It contains 0.5 to 10 % by mass , the foam volume ratio under vacuum at a liquid temperature of 20 ° C. and an absolute pressure of 0.003 MPa is less than 10 vol%, and the average particle size by the dynamic light scattering method is less than 300 nm. An aqueous dispersion of polytetrafluoroethylene characterized by being present. The polytetrafluoroethylene aqueous dispersion according to claim 1 , further containing a secondary amine and / or a tertiary amine and having a pH of 8 to 13. The polytetrafluoroethylene aqueous dispersion according to claim 1 or 2, wherein the cake ratio after standing at 25 ° C. for 3 months is 40% or less, and the redispersion ratio at that time is 95% or more. .. The binder resin has a solid content ratio of 20 to 95% by mass, and the polytetrafluoroethylene aqueous dispersion according to any one of claims 1 to 3 has a solid content ratio of 5 to 80% by mass based on polytetrafluoroethylene. A polytetrafluoroethylene function-imparting aqueous composition comprising at least. A liquid coating tool filled with the polytetrafluoroethylene function-imparting aqueous composition according to claim 4.