JP2001261908A - Fluoropolymer-based aqueous dispersion composition and coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject aqueous dispersion composition good in film foamability and coating film properties, slight in foaming tendency, and suitable to coating operation using a curtain flow coater in particular. SOLUTION: This aqueous dispersion composition is obtained by incorporating a coating composition as an aqueous dispersion containing fluoropolymer particles 0.01-100 μm in average size with 0.01-20 pt(s).wt., based on the solids of the coating composition, of 6-12C aliphatic saturated hydrocarbon and/or 7-11C aromatic hydrocarbon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorine-containing polymer-based aqueous dispersion composition which has good film-forming properties and physical properties of a coating film, has little foaming, and is particularly suitable for coating with a curtain flow coater.

[0002]

2. Description of the Related Art An aqueous dispersion containing fluoropolymer particles is generally produced by so-called emulsion polymerization using a water-soluble polymerization initiator in the presence of an anionic surfactant.
The average particle size in the aqueous dispersion (latex) is 0.05 to
Obtained in the form of a 1.0 μm colloid. This aqueous dispersion is unstable as it is, sedimentation of the polymer particles by storage, aggregation of the polymer particles by agitation is likely to occur, so a nonionic surfactant such as polyoxyethylene alkyl phenyl ether is added, The dispersion stability of the polymer particles is ensured. Therefore, bubbles are easily generated by stirring,
The generated bubbles are hard to disappear.

[0003] As a defoaming agent which suppresses the generation of bubbles or breaks the generated bubbles, silicone compounds having excellent defoaming properties have been generally used. However, the silicone-based antifoaming agent has a problem that the silicone-based antifoaming agent remaining in the coating film has an adverse effect on film forming properties and physical properties of the coating film.
In particular, when applying a coating comprising the aqueous dispersion using a curtain flow coater, there is a problem that traces of bubbles remain in the coated coating film, and the silicone compound causes the curtain to break. .

[0004] An acetylenic diol-based antifoaming agent is known as an antifoaming agent having excellent defoaming performance, but there is a problem that its efficacy is not persistent.

[0005]

As described above, the defoaming performance of a coating composition comprising an aqueous dispersion containing a fluoropolymer particle and a surfactant has a long-lasting property, and the defoaming performance can be improved without remaining in a coating film. As a result of intensive studies on antifoaming agents that do not adversely affect film properties and coating film properties, specific hydrocarbon compounds are specifically excellent in defoaming of this system and do not remain in the coating film. Further, they have found that a coating composition particularly suitable for coating with a curtain flow coater can be obtained, and have completed the present invention.

[0006]

SUMMARY OF THE INVENTION The present invention provides a fluoropolymer-based aqueous dispersion composition which has good film-forming properties and physical properties of a coating film, has less foaming, and is particularly suitable for coating with a curtain flow coater.

That is, according to the present invention, the average particle diameter is 0.01
100 parts by weight of the solid content of the aqueous dispersion containing the fluoropolymer particles having a particle size of from 100 to 100 μm and the surfactant, as a defoaming agent, an aliphatic saturated hydrocarbon having 6 to 12 carbon atoms and / or
Alternatively, an aromatic hydrocarbon having 7 to 11 carbon atoms is used in an amount of 0.01 to
The present invention relates to an aqueous dispersion composition obtained by adding 20 parts by weight, and a coating composition comprising the aqueous dispersion composition, particularly a coating composition for curtain flow coating.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The fluorine-containing polymer of the present invention is mainly used for forming a coating film for imparting non-adhesiveness and lubricity to articles to be coated. Examples of the fluorinated polymer include a homopolymer of a monomer of a fluorinated monoethylenically unsaturated hydrocarbon in which part or all of hydrogen atoms are substituted with a fluorine atom, a chlorine atom or these two types, At least two of a homopolymer and a copolymer composed of two or more monomers.
Also included are polymer mixtures of species. Specific examples are given below, but the fluoropolymers that can be used in the present invention are not limited to these.

Examples of the homopolymer include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVdF), and polyvinyl fluoride (PVF).

As the copolymer, tetrafluoroethylene (TFE) and a general formula copolymerizable with TFE: X (CF ₂ ) mOnCFＯCF ₂ (where X is a hydrogen atom, a chlorine atom or a fluorine atom, m
Is an integer of 1 to 6, n is 0 or 1, and a compound represented by the general formula: C ₃ F ₇ O [CF (CF ₃ ) CF ₂ O] _p -CF = CF ₂ (where p is Represents 1 or 2)
A copolymer with a compound represented by the general formula: X (CF ₂ ) _q CY = CH ₂ (where X is the same as above, Y is a hydrogen atom or a fluorine atom, and q is an integer of 1 to 6) Specific examples include TFE-perfluoro (alkyl vinyl ether) copolymer (PFA) and TFE-hexafluoropropylene copolymer (FEP). In addition, TFE-chlorotrifluoroethylene (CTFE) copolymer, TFE-vinylidene fluoride (VdF) copolymer, TFE-trifluoroethylene (3FH) copolymer, TFE-ethylene copolymer (ET
FE), VdF-hexafluoropropylene copolymer,
Ethylene-CTFE copolymer (ECTFE), ethylene-hexafluoropropylene copolymer, TFE-propylene copolymer and the like can also be used. VdF and TFE
And a terpolymer of hexafluoropropylene.

As the mixture of the homopolymer and the copolymer, for example, a mixture of PTFE and PFA, PTFE
And FEP, a mixture of PTFE, PFA and FEP, and a mixture of PFA and FEP.

The fluorine-containing polymer which can be used in the present invention also includes a polymer obtained by polymerizing a (meth) acrylate monomer having a perfluoroalkyl group. Such a perfluoroalkyl group-containing (meth) acrylate monomer includes a compound represented by the general formula:

[0013]

Embedded image

(Wherein, Rf is a perfluoroalkyl group having 4 to 20 carbon atoms, R ¹ is a hydrogen atom or 1 to 10 carbon atoms)
R ² is an alkylene group having 1 to 10 carbon atoms,
R ³ is a hydrogen atom or a methyl group, R ⁴ is an alkyl group having 1 to 17 carbon atoms, r is an integer of 1 to 10, and s is an integer of 0 to 10). And a homopolymer of the monomer or a copolymer of two or more monomers, and a copolymer of the monomer with another monomer which can be copolymerized with the monomer. Other monomers include, for example, alkyl esters of (meth) acrylic acid (alkyl having 1 to 20 carbon atoms), cyclohexyl or benzyl (meth) acrylate, polyethylene glycol di (meth) acrylate, N-methylol Propaneacrylamide, ethylene, vinyl chloride, vinyl fluoride, (meth) acrylamide, styrene, α
-Methylstyrene, p-methylstyrene, vinyl alkyl ether (alkyl having 1 to 20 carbon atoms), halogenated alkyl vinyl ether (alkyl having 1 to 2 carbon atoms)
0), vinyl alkyl ketone (alkyl having 1 to 2 carbon atoms)
0), maleic anhydride, butadiene, isoprene, chloroprene and the like, but are not limited thereto.

The aqueous dispersion containing the fluoropolymer particles is generally produced by so-called emulsion polymerization using a water-soluble polymerization initiator in the presence of an anionic surfactant. Average particle size is 0.0
It is obtained in the form of a colloid of 1 to 1.0 μm. This aqueous dispersion is used as it is or is appropriately coagulated and redispersed to obtain an aqueous dispersion in which particles having an average particle size of 0.01 to 100 μm are dispersed. However, since the polymer particles are unstable as they are, sedimentation of the polymer particles due to storage and aggregation of the polymer particles due to agitation tend to occur, the dispersion stability of the polymer particles is secured by adding a surfactant.

As such a surfactant as a dispersion stabilizer, for example, nonionic surfactants such as polyoxyethylene alkylphenyl ether and polyoxyethylene alkyl ether are mainly used, and nonionic surfactants such as sodium lauryl sulfate are also used. A fluorine-containing anionic surfactant, a fluorine-containing anionic surfactant such as ammonium perfluorooctanoate and the like are used in combination.

Therefore, the fluorine-containing aqueous dispersion to be defoamed in the present invention basically has an average particle diameter of 0.01 to 10%.
The fluoropolymer particles having a diameter of 0 μm, preferably 0.05 to 50 μm are stably dispersed in an aqueous liquid carrier such as water by the action of the surfactant.

The aqueous liquid carrier of the aqueous dispersion used in the present invention is mainly composed of water, but may be mixed with an organic liquid in addition to water. However, hydrocarbon compounds used as an antifoaming agent in the present invention are excluded. Examples of the organic liquid as the liquid carrier include nitrogen-containing solvents such as N-methyl-2-pyrrolidone and dimethylacetamide, oxygen-containing solvents such as γ-butyrolactone, esters such as butyl acetate, and ketones such as methyl isobutyl ketone. And at least one selected from glycol ethers such as butyl cellosolve and alcohols such as 1-butanol, but is not limited thereto.

In addition to the above-mentioned fluoropolymer particles, resin particles other than fluorine-containing ones can be added to the aqueous dispersion for the purpose of improving the coating properties such as film-forming properties and corrosion resistance. Specifically, polyamide resin, polyimide resin, polyamide imide resin, polyether sulfone resin, polyphenylene sulfide resin, phenol resin, urea resin,
Examples include particles of an epoxy resin, a urethane resin, a melamine resin, a polyester resin, a polyether resin, an acrylic resin, an acrylic silicone resin, a silicone resin, a silicone polyester resin, and the like, but are not limited thereto. The average particle size of the polymer particles other than these fluoropolymers is about 0.01 to 100 μm. The compounding amount is appropriately selected depending on the purpose, application, required performance, and the like.

The aqueous dispersion of the fluoropolymer used in the present invention has a solid content of 10 to 80% by weight, usually 20 to 70% by weight.
% By weight.

In the present invention, an aliphatic saturated hydrocarbon having 6 to 12 carbon atoms and / or an aromatic hydrocarbon having 7 to 11 carbon atoms is added to the aqueous fluoropolymer dispersion as an antifoaming agent. I do. It is the first finding of the present invention that these hydrocarbon compounds have a remarkable defoaming action on the aqueous fluoropolymer dispersion.

An aliphatic saturated hydrocarbon having 5 or less carbon atoms is not preferred because it has a low boiling point and poor defoaming performance. In addition, aliphatic saturated hydrocarbons having 13 or more carbon atoms and aromatic hydrocarbons having 12 or more carbon atoms are not preferable because their defoaming performance is weak, and furthermore, they have a high boiling point and delay the drying of the paint. It is not practical in that it easily remains.

The aliphatic saturated hydrocarbon having 6 to 12 carbon atoms that can be used in the present invention is preferably one or a mixture of two or more compounds exemplified by the following general formulas, but is not limited thereto. is not. Further, a cyclic compound such as ethylcyclohexane is also included.

[0024]

Embedded image

[0025]

Embedded image

Examples of the aromatic hydrocarbon having 7 to 11 carbon atoms include, but are not limited to, toluene, xylene, trimethylbenzene, methylethylbenzene, propylbenzene, and butylbenzene. . Also, a mixture of two or more aromatic hydrocarbons selected from these may be used. Commercially available products include Solvesso 100, Solvesso 150, and Solvesso 200 (manufactured by Exxon Chemical Co., Ltd.).

Further, at least one kind of aliphatic saturated hydrocarbon having 6 to 12 carbon atoms and at least one kind of aromatic hydrocarbon having 7 to 11 carbon atoms may be used in combination. As a commercially available product of this mixture, mineral spirit (Japanese Industrial Standard, Industrial Gasoline No. 4) can be exemplified, which is advantageous in that it can be obtained at very low cost.

The amount of the hydrocarbon compound as an antifoaming agent is 0.01 to 20 parts by weight, preferably 0.1 to 20 parts by weight, based on 100 parts by weight of the solid content of the aqueous fluoropolymer dispersion.
It is 1 to 10 parts by weight. If the amount is less than 0.01 part by weight, a sufficient defoaming effect cannot be obtained. If the amount exceeds 20 parts by weight, the dispersion stability of the fluoropolymer particles is unfavorably deteriorated.

In the present invention, other known antifoaming agents may be used together if necessary, as long as the effects of the present invention are not impaired. Other antifoaming agents include, for example, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,5-
Low HLB (hydrophilicity) such as acetylenes such as dimethyl-1-hexyn-3-ol, sorbitan laurate monoester, sorbitan laurate triester, polyethylene glycol fatty acid ester, and oxyethylene-oxypropylene block copolymer. Examples include, but are not limited to, silicone compounds such as polyether polymer surfactants, dimethyl silicone, methyl chloride silicone, and organically modified silicone. The silicone-based antifoaming agent can be used in the form of a solution in which the silicone-based compound is dissolved in an organic solvent or an emulsion in which the silicone-based compound is emulsified and dispersed in water.

The viscosity of the aqueous dispersion composition of the present invention is 0.1.
1 to 10000 mPa · s, preferably 1 to 1000 m
It is preferably adjusted to Pa · s, but is not particularly limited.

The aqueous dispersion composition of the present invention is preferably in the form of a coating composition. When prepared into a coating composition, a film-forming agent, a solid lubricant, a pigment, a filler, a pigment dispersant, an anti-settling agent, a moisture absorbing agent, depending on the use of the coating film or for the purpose of improving coating properties and coating film , Surface conditioners, thixotropic agents, viscosity modifiers, gelling inhibitors, UV absorbers, light stabilizers, plasticizers, anti-segregation agents, anti-skinning agents, anti-scratch agents, fungicides, antibacterial Additives such as an agent, an antioxidant, an antistatic agent, and a silane coupling agent.

The object to be coated with the coating composition of the present invention is iron,
Examples include metals such as aluminium, copper or alloys thereof, and inorganic materials such as enamel, glass, and ceramics, but are not limited thereto. Before coating, a base treatment such as degreasing, chemical conversion treatment, acid or alkali etching, or sand blasting may be appropriately performed according to the type and use of the paint.

The coating composition of the present invention can be applied by a coating method such as spray coating, roll coating, doctor blade coating, dip (dip) coating, impregnation, spin flow coating, curtain flow coating, etc. Is preferably used as a coating composition for curtain flow coating, which is problematic. A well-known curtain flow coater can be used.

Here, a general curtain flow coater used in the embodiment described later will be briefly described with reference to FIG.

The curtain flow coater is basically composed of a head portion 3 having a slit 4, a storage tank 5 for the liquid coating composition 1, and a coating material disposed in the storage tank 5 and having a rotating part (impeller) 7. It comprises a supply pump 6 and a base material supply conveyer 8, and the liquid paint composition 1 is supplied from a storage tank 5 at the lower part by the paint supply pump 6 to the rotating part 7 of the pump.
This is a device for feeding the head 2 to the head 3 by adjusting the peripheral speed of the outer periphery, flowing down from the slit 4, and coating the surface of the base material 2 sent by the conveyor 8.

In general, a flow control valve 9 and a filter chamber 10 for removing foreign substances (for example, aggregates having a large particle diameter) are provided in a transport pipe for feeding the coating composition from the pump 6 to the head section 3. I have.

The use of the coated article is not particularly limited, but when utilizing the non-adhesiveness of the coating film, metal cooking such as a frying pan, a pan, a grill pan, a rice cooker, an oven, a hot plate pan baking die, a kitchen knife, a gas table, etc. In the case of using the slipperiness of an appliance, an electric pot, an ice tray, a mold, a range hood, and a coating film, tools such as a saw and a file, an iron, and metal foil can be exemplified.

[0038]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

Examples 1 to 7 and Comparative Examples 1 to 4 The coating compositions were prepared by mixing the following components in the proportions (parts by weight) shown in Table 1.

(Polymer particle component) PTFE: PTFE particles having an average particle diameter of 0.28 μm Polyether resin emulsion: solid content of 30% by weight,
Emulsion of polyether urethane resin particles with molecular weight of about 2000

(Dispersion stabilizer) Nonionic surfactant: polyoxyethylene alkyl phenyl ether (molecular weight: 640) Fluorinated anionic surfactant: ammonium perfluorooctanoate Anionic surfactant: sodium lauryl sulfate

(Film-forming agent) Polyether-based film-forming agent: oxyethylene-oxypropylene block copolymer having an average molecular weight of 25,000

(PH adjuster) Succinic acid

(Pigment) Mill base: 6.75 parts by weight of deionized water, 0.72 parts by weight of a polyether-based nonionic surfactant, 0.18 parts by weight of ammonium perfluorooctanoate, 0.1% by weight of carbon.
A mixture obtained by mixing a mixture of 90 parts by weight and 0.45 parts by weight of bengara (α-diiron trioxide) with a ball mill.

(Filler) Titanium dioxide-coated mica: Mica coated with titanium dioxide having a specific gravity of about 3 and an average particle diameter of 30 μm

(Aqueous liquid carrier) Deionized water

(Antifoaming agent) n-octane (7 carbon atoms) n-decane (10 carbon atoms) n-dodecane (12 carbon atoms) trimethylbenzene (9 carbon atoms) xylene (8 carbon atoms) Mineral spirit: Nippon Kogyo Standard, mixture of saturated and aromatic hydrocarbons in industrial gasoline No. 4, boiling range;
160-200 ° C n-pentane (carbon number 5) polyether-modified silicone oil

The defoaming effect of each of the obtained aqueous dispersion compositions was examined in the following manner. Table 1 shows the results.

(Defoaming Effect of Antifoaming Agent) Evaluation was made by measuring the foaming amount. The measurement of the foaming amount was performed as follows.

20 ml of the paint was placed in a measuring cylinder having a capacity of 100 ml, and the amount of the foam was read from the scale of the measuring cylinder by vigorously shaking up and down. When the amount of foam is 10 ml or less, it is evaluated that the defoaming effect of the added defoamer is good.

Example 7 A rotating part (impeller) of a centrifugal pump was applied to an aluminum plate which had been previously degreased with the coating composition (aqueous dispersion) shown in Example 7 of Table 1 using a curtain flow coater of FIG. ), The outer peripheral speed is 4.7 m / sec, and the conveyor speed is 8
Approximately 3 minutes after starting curtain flow coater operation at 5 m / min
After 0 minutes, painting was performed. 80-100 after painting
After drying at 10 ° C. for 10 minutes, baking at 380 ° C. for 20 minutes (film thickness after firing: 22 μm), cooling to room temperature, and observing the properties of the coating film in the following manner.

(Properties of Coating Film) Using a known curtain flow coater whose schematic diagram is shown in FIG. 1, coating was performed by the following method, and the appearance of the obtained coating film was observed.

The aqueous dispersion composition was applied to a curtain flow coater (rotating part of centrifugal pump (impeller)) shown in FIG.
Peripheral velocity of 4.7 m / sec, gap of slit 4 0.5
mm, conveyor effective width 300 mm, conveyor length 1010
mm (two installations). (Conveyor speed was adjusted to 80 to 100 m / min), and a pre-degreased aluminum plate was coated at 18 to 22 ° C. 80 after painting
After drying at １００100 ° C. for 10 minutes, baking at 380 ° C. for 20 minutes and cooling to room temperature, the appearance of the coating film was observed. The film thickness after firing was 22 μm. The viscosity (20 ° C.) during use (coating) was 106 mPa · s, and coating was started 30 minutes after the start of operation of the curtain flow coater.

The viscosity was measured using a B-type viscometer (BM type) manufactured by Tokyo Keiki Co., Ltd. The measurement was performed at 20 ° C. by rotating the rotor at 60 rpm for 2 minutes using two rotors.

The appearance of the dried coating film obtained 30 minutes after the start of coating was examined by the following method. The results were "good" by visual observation and 5 points by microscopic observation.

Evaluation of Coating Appearance Visual Observation: The presence or absence of traces or dents of bubbles on the coating film surface is visually observed. Microscopic observation: Nikon Corporation's metal clear boundary (30 magnification)
)) To observe the presence or absence of the trace of the bubble, and evaluate the number of the trace of the bubble in five steps. 1 point = more than 20 traces of foam per square mm 2 points = more than 10 and less than 20 traces of foam per square mm 3 points = more than 10 traces of foam per square mm Below 4 points = 1 to 3 traces of bubbles per square mm 5 points = No trace of bubbles

Comparative Example 4 Coating was performed using a curtain flow coater under the same conditions as in Example 7 except that the composition shown in Comparative Example 3 in Table 1 was used as the aqueous dispersion composition. When the coating film after baking was visually observed, traces of bubbles were observed, and a smooth coating film was not formed.

[0058]

[Table 1]

[0059]

The aqueous dispersion composition of a fluoropolymer to which the specific hydrocarbon compound of the present invention is added as an antifoaming agent has little foaming and is suitable for coating with a curtain flow coater. The coating film obtained by applying the composition with a curtain flow coater has no trace of bubbles even when observed with a microscope, and is smooth.

[Brief description of the drawings]

FIG. 1 is a schematic view of a curtain flow coater used in Examples.

[Description of Signs] 1 Liquid paint composition 2 Substrate 3 Head part 4 Slit 5 Storage tank 6 Paint supply pump 7 Rotating part 8 Substrate supply conveyor 9 Flow control valve 10 Filter chamber

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 4J002 BD121 EA017 EA037 EA038 FA081 FD207 FD208 FD316 GH01 HA06 4J038 CA021 CB031 CC021 CC081 CD021 CD091 CD101 CD111 CD121 CE051 CG071 CG141 CG171 CH051 MA08 MA03 CH081 MA08 PC03

Claims (3)

[Claims] An antifoaming agent having an average particle diameter of 0.01 to 100 μm and having a carbon content of 6 to 100 parts by weight per 100 parts by weight of a solid content of an aqueous dispersion containing a surfactant and a surfactant.
12 aliphatic saturated hydrocarbons and / or 7 to 7 carbon atoms
An aqueous dispersion composition obtained by adding 0.01 to 20 parts by weight of the aromatic hydrocarbon of No. 11. 2. A coating composition comprising the aqueous dispersion composition according to claim 1. 3. The coating composition according to claim 2, which is a coating composition for curtain flow coating.