JP2012025836A - Fluorine resin aqueous dispersion and coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorine resin aqueous dispersion containing a VdF-based (vinylidene fluoride-based) seed polymer, wherein the VdF-based seed polymer can improve glossiness while maintaining the properties of a VdF-based fluorine resin aqueous paint having high fluorine content.SOLUTION: The fluorine resin aqueous dispersion is obtained by: using, as seed particles, VdF-based copolymer particles containing a VdF monomer; and seed-polymerizing a monomer containing an acrylic monomer. The fluorine resin aqueous dispersion contains the VdF-based seed polymer. In the VdF-based seed polymer, (1) the content of an acrylic monomer unit is ≥50 mass%; and (2) the melt flow rate at 250°C when the seed polymer weighs 10 kg is ≤30 g/10 min.

Description

  The present invention relates to an aqueous fluororesin dispersion in which water resistance does not decrease despite the reduced fluorine content, and the processability and gloss of the coating film are improved, and a coating composition using the same .

  A fluororesin has excellent properties such as weather resistance, stain resistance, solvent resistance, water resistance, and moisture resistance, and is used as a weather resistant paint resin.

  The weather-resistant fluororesin paint includes a solvent-type paint used by dissolving in an organic solvent, an aqueous paint used by dispersing a water-modified fluororesin in water, and a powder paint used as a powder. In addition, the water-based paint has the feature that the influence on the environment can be reduced and the painting is simple.

  Obtained by seed polymerization of acrylic monomer using vinylidene fluoride (VdF) copolymer produced using a reactive surfactant as seed particles as a fluorine resin effective for weather-resistant fluororesin aqueous coatings It is known that the obtained VdF seed polymer has small particles and is excellent in sedimentation stability even at a high concentration, and is suitable for an aqueous paint (Patent Document 1).

  Patent Document 2 discloses that a composition comprising a synthetic resin emulsion and a tetrafunctional silicate is excellent in antifouling property and weather resistance, forms a highly glossy coating film, and has excellent sedimentation stability. Are listed.

Japanese Patent Application Laid-Open No. 08-067795 JP-A-11-148019

  By the way, the weather resistance, water resistance, and moisture resistance, which are the characteristics of the fluororesin, are basically related to the fluorine content, and these characteristics improve as the fluorine content increases. On the other hand, the fluorine-containing monomer used as the raw material for the fluororesin is relatively expensive, and as a result of increasing the fluorine content, the price of the fluororesin increases.

  In order to reduce the fluorine content, the amount (ratio) of the acrylic polymer to be additionally polymerized should be increased. However, when the present inventors examined a conventional fluorine-containing seed polymer, the acrylic polymer was simply It has been found that simply increasing the proportion of coalescence greatly deteriorates the water resistance and weather resistance, and does not satisfy the required characteristics as a weather resistant paint.

  As a result of further studies, even if the acrylic monomer content is increased and the fluorine content is lowered, the gloss of the conventional VdF fluororesin aqueous paint can be maintained and the gloss can be further improved. The present inventors have found a VdF seed polymer that can be produced and completed the present invention.

The present invention is obtained by seed polymerization of a monomer containing an acrylic monomer using vinylidene fluoride (VdF) copolymer particles as seed particles, and (1) Content of acrylic monomer units Is 50% by mass or more,
(2) It is related with the fluororesin aqueous dispersion containing the VdF type seed polymer whose melt flow rate (250 degreeC, 10 kg) is 30 g / 10min or less.
The present invention also relates to a fluororesin aqueous coating composition containing the fluororesin aqueous dispersion of the present invention.

  INDUSTRIAL APPLICABILITY The present invention can provide an aqueous fluororesin dispersion containing a VdF seed polymer that can improve the gloss while maintaining the characteristics of a high fluorine content VdF fluororesin aqueous paint.

  The fluororesin aqueous dispersion of the present invention includes a VdF seed polymer obtained by seed polymerization of a monomer containing an acrylic monomer using VdF copolymer particles as seed particles and satisfying specific physical properties. .

  First, VdF copolymer particles that are seed particles will be described.

  The VdF copolymer is a copolymer composed of VdF and another fluorine monomer. Examples of other fluorine-based monomers include tetrafluoroethylene (TFE), trifluoroethylene (TrFE), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), and vinyl fluoride (VF). However, from the viewpoint of copolymerization reactivity of VdF, TFE, HFP, and CTFE are preferable, and it is particularly preferable that TFE is included.

  Specific examples of the VdF copolymer include, for example, VdF / TFE, VdF / TFE / HFP, VdF / TFE / CTFE, VdF / TFE / TrFE, VdF / CTFE, VdF / HFP, VdF / TFE / HFP / CTFE, and the like. In view of good weather resistance, chemical resistance and solvent resistance, it is preferable that at least one fluoroolefin is contained. Of these, VdF / TFE / HFP and VdF / TFE / CTFE are preferable.

（式中、ＸはＨまたはＳＯ₃Ｙ（ＹはＮＨ₄またはアルカリ金属原子）；ｎは０〜１９の整数）で示される非フッ素反応性界面活性剤などが例示できる。反応性界面活性剤は、前記モノマーの組み合わせに対して０．００１〜０．１モル％を含むようにすればよい。反応性界面活性剤を共重合する場合は、アクリル樹脂との相溶性が良好な点から、ＶｄＦ／ＴＦＥ／ＣＴＦＥとＣＨ₂＝ＣＦＣＦ₂ＯＣＦ（ＣＦ₃）ＣＦ₂ＯＣＦ（ＣＦ₃）ＣＯＯＮＨ₄との組み合わせが好ましい。 Further, a reactive surfactant may be copolymerized. The reactive surfactant, for example, _{CF 2 = CFCF 2 COONH 4,} CH 2 = CFCF 2 OCF (CF 3) CF 2 OCF (CF 3) COONH 4, CH 2 = CFCF 2 OCF (CF 3) COONH 4 , etc. fluorine-containing reactive ^{_{surfactant; CH 2 = CR 1 -R 2}} -O- (AO) p -X (1)
(Wherein R ¹ is a hydrogen atom or an alkyl group; R ² is an alkylene group having 2 or more carbon atoms; AO is a linear or branched oxyalkylene group having 2 to 4 carbon atoms; p is a positive integer; X is H or SO ₃ Y (Y is NH ₄ or an alkali metal atom); when a plurality of AO are present, they may be the same or different from each other, and may form two or more types of block structures ) Non-fluorine reactive surfactant represented by

(Wherein, X is H or SO ₃ Y (Y is NH ₄ or an alkali metal atom); n is an integer of 0 to 19) and the like. What is necessary is just to make a reactive surfactant contain 0.001-0.1 mol% with respect to the combination of the said monomer. When copolymerizing the reactive surfactant, VdF / TFE / CTFE and CH ₂ = CFCF ₂ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COONH ₄ are used because of good compatibility with the acrylic resin. The combination of is preferable.

  The copolymerization ratio of VdF and other fluorine-based monomers in the VdF copolymer is preferably 60/40 to 95/5 mol%, and more preferably 70/30 to 95/5 mol%. If the VdF is less than 60 mol%, the compatibility with the acrylic polymer tends to decrease, and if it exceeds 95 mol%, the seed particles are converted into an acrylic monomer (for example, acrylic ester, methacrylic ester, etc.). Swellability decreases, the monomer does not swell quickly into the seed particles during seed polymerization, and the cast film obtained from the aqueous dispersion has poor transparency. However, there is a tendency that gloss cannot be obtained.

  A known method is used as a method for producing the VdF copolymer particles, and it is used for the next seed polymerization in the form of an emulsion in which fine particles having an average particle size of 200 nm or less are dispersed.

  The seed polymerization of the acrylic monomer can be performed by an emulsion polymerization method. When an acrylic monomer is emulsion-polymerized in the presence of fluorine-containing polymer particles, the acrylic monomer first swells into VdF copolymer particles, and at this point, the monomer is uniformly dissolved in the monomer. As a result, the monomer is polymerized by adding an initiator to form a seed polymer, and the molecular chains of the VdF copolymer and the acrylic polymer are entangled. It is thought that the compatible solution particle was formed.

  In such seed polymerization, a surfactant, a polymerization initiator, a chain transfer agent, and in some cases a chelating agent, a pH adjuster and a solvent are usually added to an aqueous medium containing VdF copolymer particles. The monomer polymerization reaction is carried out at a temperature of about 20 to 90 ° C. for about 0.5 to 6 hours.

  In conventional seed polymerization, halogenated hydrocarbons (for example, chloroform, carbon tetrachloride, etc.), mercaptans (for example, n-dodecyl mercaptan, t-dodecyl mercaptan, n-octyl mercaptan) and the like are used as chain transfer agents. In order to increase the proportion of acrylic polymer, which is one of the objects of the present invention, and to improve water resistance and moisture resistance, usually about 0.5 to 5.0% by mass of the system monomer is added. It is important to reduce the chain transfer agent to less than 0.5% by weight. By reducing the addition amount of the chain transfer agent, the molecular weight of the acrylic polymer of the seed polymer particles obtained is increased, especially the durability against hot water of 40 ° C. or higher, and the film-forming property in drying in a short time is improved. .

  The polymerization initiator is not particularly limited as long as it can generate radicals that can be used for free radical reaction in an aqueous medium at a temperature of 20 to 90 ° C. In some cases, it can be used in combination with a reducing agent. It is. Examples of water-soluble polymerization initiators include ammonium persulfate (APS), hydrogen peroxide, 2,2-azobis (2-amidinopropane) hydrochloride (AIBA); examples of reducing agents include sodium pyrobisulfite and sodium bisulfite. And sodium L-ascorbate. Examples of the oil-soluble polymerization initiator include diisopropyl peroxydicarbonate (IPP), benzoyl peroxide, dibutyl peroxide, azobisisobutyronitrile (AIBN), and the like. The amount of the polymerization initiator used is usually about 0.05 to 2.0 parts by mass per 100 parts by mass of the acrylic monomer, but when the molecular weight needs to be increased, it is suppressed to 0.5 parts by mass or less. It is also effective.

  Other polymerization conditions may be normal conditions. For example, as the surfactant used to ensure the stability of the seed particles, an anionic, nonionic or anionic-nonionic combination is used, and an amphoteric surfactant may be used in some cases. it can.

  Examples of the anionic surfactant include higher alcohol sulfate, alkylsulfonic acid sodium salt, alkylbenzenesulfonic acid sodium salt, succinic acid dialkylester sulfonic acid sodium salt, and alkyldiphenyl ether disulfonic acid sodium salt. Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkyl phenyl esters, sorbitan alkyl esters, glycerin esters or derivatives thereof. Etc. are exemplified. The amount of the surfactant used is usually about 0.05 to 5.0 parts by mass per 100 parts by mass of the acrylic monomer.

  The polymerization temperature is preferably in the range of 20 to 90 ° C.

  Seed polymerization is a known method, for example, a method in which the entire amount of the acrylic monomer is charged into the reaction system in the presence of VdF copolymer particles, and a part of the acrylic monomer is charged and reacted. The remaining can be continuously or dividedly charged, or the entire amount of acrylic monomer can be charged continuously. It is also possible to seed polymerize an acrylic monomer in an aqueous dispersion in which two or more VdF copolymers coexist.

  Examples of acrylic monomers include, in addition to acrylic acid and methacrylic acid, reactivity of alkyl alkyl ester having 1 to 18 carbon atoms and alkyl alkyl ester having 1 to 18 carbon atoms. Examples thereof include α, β-unsaturated monomers and monomers having an ethylenically unsaturated unit copolymerizable therewith.

  Examples of alkyl acrylates having 1 to 18 carbon atoms in the alkyl group include, for example, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, and the like. Can give.

  Examples of the alkyl ester having 1 to 18 carbon atoms in the alkyl group include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-propyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate and the like. be able to.

  In addition, acrylamide compounds such as acrylamide, methacrylamide, N-methylacrylamide, N-methylolacrylamide, N-butoxymethylacrylamide, N-methylolmethacrylamide, N-methylmethacrylamide, N-butoxymethylmethacrylamide; hydroxyethyl acrylate Hydroxyl group-containing acrylic esters such as hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate; epoxy group-containing acrylic esters such as glycidyl acrylate and glycidyl methacrylate; γ-trimethoxysilane methacrylate, γ-triethoxy Examples include silanol group-containing acrylic acid esters such as silane methacrylate; acrylonitrile.

  Among these, acrylic acid ester, methacrylic acid ester, acrylic acid, methacrylic acid and the like are preferable from the viewpoint of compatibility with the VdF copolymer.

  Monomers including acrylic monomers include, in addition to acrylic monomers, unsaturated carboxylic acids such as maleic acid and crotonic acid; aldehyde group-containing monomers such as acrolein; vinyl compounds such as styrene (St) May be included.

  The acrylic monomer to be seed-polymerized is supplied in an amount that occupies 50% by mass or more of the obtained VdF-based seed polymer. The amount is preferably 60% by mass or more, more preferably 70% by mass or more of the VdF seed polymer.

The VdF seed polymer obtained by seed polymerization is
(1) The content of the acrylic monomer unit is 50% by mass or more, and (2) the melt flow rate (250 ° C., 10 kg) is 30 g / 10 min or less.

  When the content of the acrylic monomer unit is 50% by mass or more, the gloss and water resistance of the coating film are good, and when it is 70% by mass or more, the durability to warm water of 40 ° C. or more is excellent. The upper limit is about 90% by mass.

  Although the fluorine content is relatively reduced by increasing the content of the acrylic monomer unit, the fluorine content is 38% by mass in consideration of the fluorine content of the VdF copolymer as the seed particle. The following is desirable. When it is 38% by mass or less, the coating film exhibits high gloss. Preferably it is 35 mass% or less. In particular, when the content is 30% by mass or less, the sharpness is excellent. On the other hand, it is desirable that it is 10 mass% or more from the surface of a weather resistance. More preferably, it is 15 mass% or more.

  Melt flow rate (MFR) (250 ° C., 10 kg) is an index of molecular weight. When MFR is 30 g / 10 min or less, the water resistance is good, especially when it is 20 g / 10 min or less. Excellent initial water resistance in severe cases. The lower limit is about 0.01 g / 10 minutes. When the MFR becomes small (when the molecular weight is increased), the film-forming property may be lowered, and the initial water resistance may be lowered in severe conditions such as drying for a short time.

  The average particle diameter of the VdF seed polymer particles is preferably 250 nm or less, more preferably 50 to 250 nm, and particularly preferably 100 to 160 nm. When the average particle diameter is less than 50 nm, the viscosity of the aqueous dispersion increases, and there is a tendency that a high concentration aqueous dispersion cannot be obtained. When the average particle diameter exceeds 250 nm, the particles settle and solidify during storage of the aqueous dispersion. Furthermore, there is a tendency that the gloss does not appear when the coating film is prepared.

  The concentration of the VdF seed polymer particles in the VdF seed polymer particle dispersion is preferably 30 to 60% by mass, more preferably 35 to 55% by mass, and particularly preferably 35 to 50% by mass. When the concentration is less than 30% by mass, it is difficult to adjust the viscosity during coating, and the drying of the coating tends to be slow, and when it exceeds 60% by mass, the stability of the dispersion system tends to decrease.

  The aqueous fluororesin dispersion in the present invention can be prepared by dispersing VdF seed polymer particles in water.

  As a method of dispersing in water, forced stirring may be used, or a known surfactant may be used.

  As a preferable surfactant, for example, an anionic surfactant, a nonionic surfactant or a combination thereof can be used, and an amphoteric surfactant or a cationic surfactant can be used in some cases.

  As the anionic surfactant, for example, a sodium salt of a higher alcohol sulfate, a sodium alkylbenzene sulfonate, a sodium salt of a dialkyl succinate sulfonic acid or a sodium salt of an alkyl diphenyl ether sulfonic acid can be used. Among these, preferred examples include sodium alkylbenzene sulfonate, sodium lauryl sulfate, polyoxyethylene alkyl (or alkylphenyl) ether sulfonate, and the like. As the nonionic surfactant, for example, polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether can be used. Preferred specific examples are polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether and the like. As the amphoteric surfactant, lauryl betaine is suitable. As the cationic surfactant, for example, alkyl pyridinium chloride, alkyl ammonium chloride and the like can be used. Further, a surfactant copolymerizable with the monomer, for example, sodium styrenesulfonate, sodium alkylarylsulfonate, etc. can be used.

  The aqueous fluororesin dispersion of the present invention is a dispersion of VdF seed polymer particles in water, but a hydrophilic organic solvent such as alcohols may be added.

  In addition, when the VdF seed polymer particles contain a carboxyl group such as acrylic acid, methacrylic acid, or carboxylic anhydride, it is preferable to neutralize in order to improve water dispersibility. Specifically, for example, an ammonium salt, an amine salt or an alkali metal salt is preferable. Neutralization may be performed before, during or after mixing with water.

  The neutralizing agent used for neutralization is ammonia; organic amines such as diethylamine, ethylethanolamine, diethanolamine, monoethanolamine, monopropanolamine, isopropanolamine, ethylaminoethylamine, hydroxyethylamine, diethylenetriamine; sodium hydroxide, Examples include alkali metal hydroxides such as potassium hydroxide. Of these, ammonia, triethylamine, and diethanolamine are preferable in terms of convenience in availability and stability of the emulsion, and ammonia and triethylamine are particularly advantageous in terms of easy handling.

  The neutralizing agent is preferably used in the form of an aqueous solution, but may be used in the form of gas or solid content.

  The aqueous fluororesin dispersion of the present invention can be blended with other resins and various additives to form an aqueous coating composition.

  Examples of other resins include acrylic resins, polyurethane resins, and polyester resins.

  For example, surfactants, pigments, dispersants, thickeners, preservatives, ultraviolet absorbers, antifoaming agents, leveling agents and the like may be blended in the aqueous coating composition of the present invention.

  As the surfactant, those exemplified in the description of the stabilization of the aqueous dispersion can be used.

  In addition, as a thickener, Adecanol UH-420 (manufactured by Asahi Denka Kogyo Co., Ltd.), Primal QR708 (manufactured by Rohm and Haas Co., Ltd.) and the like, and as an antifoaming agent, Byk028 (Bic Chemie Japan Co., Ltd.) and the like are used. Examples of the dispersant include Byk190 (Bic Chemie Japan Co., Ltd.) and SN Dispersant 5027 (San Nopco Co., Ltd.).

  The aqueous coating composition of the present invention is useful as various coating materials such as weather-resistant coatings, electrodeposition coatings, coil coating coatings, automotive coatings, graffiti prevention coatings, and heavy anticorrosion coatings. As a coating method, a normal coating method used for those paints, for example, roll coating, dipping, brush coating, spraying, roller, or an electrodeposition coating method can be employed.

  The coating composition of the present invention is particularly effective for painting on the roofs and walls of outdoor buildings in harsh natural environments because it has excellent weather resistance, stain resistance, solvent resistance, water resistance and the like.

  Next, the present invention will be described more specifically based on synthesis examples and examples, but the present invention is not limited to these examples.

Analysis and measurement in the present invention were performed by the following methods.
(1) Fluorine content (% by mass)
Apparatus: Automatic sample combustion apparatus (AQF-100 manufactured by Mitsubishi Chemical Corporation), ion chromatograph (ICS-1500 Ion Chromatography System manufactured by DIONEX) Built-in measuring method: Elemental analysis of 3 mg sample is performed with the above apparatus.
(2) MFR (g / 10 min)
Apparatus: Dynasco melt index tester manufactured by Yasuda Seiki Seisakusho Co., Ltd. Measurement method: Approximately 6 g of sample is put into a 0.376 inch ID cylinder maintained at 250 ° C. ± 0.5 ° C. and left for 5 minutes to equilibrate the temperature. After reaching the condition, it is extruded through an orifice of 0.0825 inch diameter and 0.315 inch length under a 10 kg piston load. The value is an average value of three samples collected at the same time.
(3) Average particle size measuring device: Microtrack UPA manufactured by HONEYWELL
Measurement method: dynamic light scattering method The emulsion to be measured is diluted to a concentration measurable with pure water to make a sample, and measurement is performed at room temperature. The number average diameter of the obtained data is defined as the particle diameter.
(4) 60 ° specular gloss The coating composition is spread on a glass plate using an applicator so that the coating thickness becomes 40 μm, and dried at room temperature for 1 week to prepare a test coating plate. JIS K5600 In accordance with -4--7, the surface gloss of the test coated plate is measured using a variable angle gloss meter (Nippon Denshoku Industries Co., Ltd. VGS-SENSOR).

Production Example 1
(Production of VdF copolymer seed particles)
In a 2 L stainless steel autoclave, 500 g of ion exchange water, formula:
_{CH 2 = C (CH 3)} -CH 2 CH 2 -O- (BO) 6 - (EO) 10 -SO 3 NH 4
(Wherein BO is a butylene oxide unit; EO is a CH ₂ CH ₂ O or CH (CH ₃ ) O unit) 0.10 g (200 ppm / water (water as a polymerization medium; water as follows) The same)), and the system was sufficiently replaced with nitrogen gas, and then the pressure was reduced. Subsequently, a VdF / TFE / CTFE (= 74/14/12 mol%) mixed monomer was injected into the polymerization tank so that the internal pressure became 0.75 to 0.80 MPa, and the temperature was raised to 70 ° C. .

  Next, a polymerization initiator solution in which 1.0 g (2000 ppm / water) of ammonium persulfate (APS) was dissolved in 4 ml of ion-exchanged water and 0.75 g (1500 ppm / water) of ethyl acetate were injected with nitrogen gas and stirred at 600 rpm. The reaction was started.

  When the internal pressure began to decrease as the polymerization progressed, a VdF / TFE / CTFE (= 74/14/12 mol%) mixed monomer was supplied so that the internal pressure was maintained at 0.75 to 0.80 MPa. . 2 hours and 5 minutes after the start of polymerization, unreacted monomers were released, and the autoclave was cooled to obtain a dispersion of a VdF-based (VdF / TFE / CTFE) copolymer having a solid content concentration of 10.6% by mass. .

Example 1
(Production of aqueous dispersion of VdF seed polymer)
Into a 2 L four-necked flask equipped with a stirring blade, a cooling tube, and a thermometer, 90 g of the aqueous VdF copolymer dispersion obtained in Production Example 1 was charged, and the seed particles used for seed polymerization were charged into the flask. In order to ensure stability, 707SF (manufactured by Nippon Emulsifier Co., Ltd.) as a surfactant is 2.6% by mass based on the solid content of the VdF copolymer, and RMA-450M (manufactured by Nippon Emulsifier Co., Ltd.) is used as a VdF system. 3 mass% was added with respect to copolymer solid content. The mixture was heated in a water bath with stirring, and the temperature in the flask was raised to 75 ° C. Separately, 63.2 / 35.7 / 1.1 (molar ratio) of methyl methacrylate (hereinafter abbreviated as MMA), butyl acrylate (hereinafter abbreviated as BA) and acrylic acid (hereinafter abbreviated as AA). A mixed emulsion of a mixed monomer (98 g) and 16 ml of a 1% aqueous solution of APS (an amount corresponding to 0.158% by weight of the mixed monomer) was prepared and dropped into a flask over 2 hours to polymerize. did. 2.5 hours after the start of the polymerization, the temperature in the flask was raised to 80 ° C., kept for 2 hours, cooled, neutralized with ammonia water to adjust the pH to 7, filtered through a 300 mesh wire mesh, and blue An aqueous dispersion of white VdF seed polymer particles (average particle size 200 nm) of the present invention was produced.

  The resulting VdF seed polymer particles had a fluorine content of 18% by mass and an acrylic polymer content of 70% by mass. Moreover, MFR (250 degreeC, 10 kg) was 0.98 g / 10min.

(Preparation of white paint composition)
The aqueous dispersion of VdF seed polymer particles obtained above and the additive were mixed at the following blending ratio and sufficiently mixed using a disper stirrer to prepare a white coating composition.
Aqueous dispersion of VdF seed polymer 65.00 parts by weight Water 9.12 parts by weight Titanium oxide 31.39 parts by weight Pigment dispersant 2.35 parts by weight Antifreeze agent 1.79 parts by weight pH adjuster 0.04 parts by weight Part Antifoaming agent 0.11 parts by weight Thickener 0.38 parts by weight Film-forming aid 2.35 parts by weight

In addition, each used component is the following.
Titanium oxide: Ishihara Sangyo Co., Ltd. Taipaek CR-97 (trade name)
Pigment dispersant: Nop Cospers SN-5027 (trade name) manufactured by San Nopco
Antifreezing agent: Ethylene glycol pH adjuster: Ammonia water defoaming agent: BYK028 (trade name) manufactured by Big Chemie
Thickener: Adecanol UH-420 (trade name) manufactured by Asahi Denka Kogyo Co., Ltd.
Film-forming aid: Diethyl adipate

  The following test was performed on the obtained white paint composition. The results are shown in Table 1.

(Initial water resistance)
The coating composition was extended to 150 g / m ² using a brush on a galvalume plate coated with ATTSU-9 undercoat and ATTSU-9 intermediate coat (both made by Nippon Paint Co., Ltd.), and at 23 ° C. Dry for 24 hours to prepare test plate. This test coated plate was immersed in 23 ° C. water for 1 day in accordance with JIS K5600-6-2 to evaluate the state of the coating film, then dried at 23 ° C. for 1 day, swollen (JIS K5600-8-2), cracked ( The grade of JIS K5600-8-4) and peeling (JIS K5600-8-5) is evaluated according to the following criteria.

Evaluation criteria for blister grade (JIS K5600-8-2) Density is divided into grades 0-5 (smaller is 0), and sizes are divided into grades S1-S5 (smaller S1). It is described as S1).

Evaluation criteria of cracking grade (JIS K5600-8-4) Density is graded from 0 to 5 (smaller is 0), size is from S0 to S5 (S0 is smaller), and depth is a It is divided into ˜c grades (a is shallower), and is described as, for example, 2 (S1) b.

Evaluation standard of peeling grade (JIS K5600-8-5) Density is graded 0-5 (smaller is 0), size is graded S1-S5 (smaller is S1), depth is a It is divided into ˜b grades (a is shallower), and is described as 2 (S1) a, for example.

(General water resistance test)
The test coated plate prepared in the same manner as the initial water resistance was dried at 23 ° C. for 1 week, immersed in 23 ° C. water for 6 days in accordance with JIS K5600-6-2, then dried at 23 ° C. for 1 day, and swollen (JIS K5600- 8-2), crack (JIS K5600-8-4), and peel (JIS K5600-8-5) are evaluated according to the above initial water resistance standards.

(Preparation of clear paint composition)
The clear dispersion composition was prepared by mixing the aqueous dispersion of VdF-based seed polymer particles obtained above and the additive in the following blending ratio and mixing thoroughly using a disper stirrer.
Aqueous dispersion of VdF seed polymer 65.00 parts by weight Water 9.12 parts by weight Defoamer 0.11 parts by weight Thickener 0.38 parts by weight Film-forming aid 2.35 parts by weight

  In addition, the used antifoamer, thickener, and film-forming aid are the same as those used for the white paint composition.

  The following tests were performed on the obtained clear coating composition. The results are shown in Table 1.

(Water whitening test)
The coating composition is stretched on a glass plate using an applicator so that the coating thickness becomes 40 μm, and dried at 23 ° C. for 1 day to prepare a test coating plate. According to JIS K5600-6-2, 23 Immerse in water at 0 ° C. for 3 days, then dry at 23 ° C. for 1 day, and visually evaluate the whitening state of the coating film.

(Hot water whitening test)
A test coated plate produced in the same manner as the initial water resistance was dried at 23 ° C. for 1 week, immersed in warm water at 50 ° C. for 7 days, the state of the coating film was evaluated, then dried at 23 ° C. for 1 day, and swollen (JIS K5600 -8-2), crack (JIS K5600-8-4), and peel (JIS K5600-8-5) are evaluated according to the above initial water resistance standards.

Example 2
(Production of aqueous dispersion of VdF seed polymer)
Seed was made in the same manner as in Example 1 except that the VdF copolymer aqueous dispersion obtained in Production Example 1 was used and the addition amount of APS was added in an amount corresponding to 0.08% by mass of the mixed monomer. Polymerization was carried out to produce an aqueous dispersion of VdF seed polymer particles (average particle size 239 nm) of the present invention.

  The resulting VdF seed polymer particles had a fluorine content of 18% by mass and an acrylic polymer content of 70% by mass. Moreover, MFR (250 degreeC, 10 kg) was 0.73 g / 10min.

  A white coating composition and a clear coating composition were prepared in the same manner as in Example 1 except that the aqueous dispersion of VdF-based seed polymer particles obtained above was used, and various characteristics were examined. The results are shown in Table 1.

Example 3
(Production of aqueous dispersion of VdF seed polymer)
Seed was made in the same manner as in Example 1 except that the VdF copolymer aqueous dispersion obtained in Production Example 1 was used and the addition amount of APS was added in an amount corresponding to 0.05% by mass of the mixed monomer. Polymerization was performed to produce an aqueous dispersion of the VdF seed polymer particles (average particle size 230 nm) of the present invention.

  The resulting VdF seed polymer particles had a fluorine content of 18% by mass and an acrylic polymer content of 70% by mass. Moreover, MFR (250 degreeC, 10 kg) was 1.05 g / 10min.

  A white coating composition and a clear coating composition were prepared in the same manner as in Example 1 except that the aqueous dispersion of VdF-based seed polymer particles obtained above was used, and various characteristics were examined. The results are shown in Table 1.

Example 4
Into a 2 L four-necked flask equipped with a stirring blade, a cooling tube, and a thermometer, 600 g of the VdF copolymer aqueous dispersion obtained in Production Example 1 was charged. In order to ensure stability, Eleminol JS-20 (manufactured by Sanyo Kasei Kogyo Co., Ltd.) was added as a surfactant in an amount of 1.5% by mass based on the solid content of the VdF copolymer. Separately, MMA / BA / AA 70/28/2 (mole% ratio) mixed monomer (275 g) was prepared under stirring, and this mixed monomer was dropped into the flask over 0.5 hours. Stir for 1 hour. Thereafter, RMA-450M (manufactured by Nippon Emulsifier Co., Ltd.) is 3% by mass with respect to the VdF copolymer solid content, and RS-3000 (manufactured by Nippon Emulsifier Co., Ltd.) is based on the VdF copolymer solid content. 0.3% by mass was added, and the mixture was heated in a water bath with stirring to raise the temperature in the flask to 75 ° C. 40 ml of a 1% aqueous solution of APS was added over 4 hours to initiate polymerization. 4 hours after the start of the polymerization, the temperature in the flask was raised to 80 ° C., kept for 2 hours, cooled, neutralized with ammonia water to adjust the pH to 7, and filtered through a 300-mesh wire mesh. An aqueous dispersion of VdF seed polymer particles (average particle diameter of 134 nm) of the present invention was produced.

  The resulting VdF seed polymer particles had a fluorine content of 30% by mass and an acrylic polymer content of 50% by mass. Moreover, MFR (250 degreeC, 10 kg) was 0.07 g / 10min.

  A white coating composition and a clear coating composition were prepared in the same manner as in Example 1 except that the aqueous dispersion of VdF-based seed polymer particles obtained above was used, and various characteristics were examined. The results are shown in Table 1.

Example 5
Into a 2 L four-necked flask equipped with a stirring blade, a cooling tube, and a thermometer, 90 g of the aqueous VdF copolymer dispersion obtained in Production Example 1 was charged, and the seed particles used for seed polymerization were charged into the flask. In order to ensure stability, 707 SF (manufactured by Nippon Emulsifier Co., Ltd.) as a surfactant was added at 6.6% by mass relative to the solid content of the VdF copolymer. The mixture was heated in a water bath with stirring, and the temperature in the flask was raised to 75 ° C. Separately, a mixed solution of 63.2 / 35.7 / 1.1 (mol% ratio) monomer mixture (98 g) of MMA, BA and AA was prepared, and 16 ml of 1% aqueous solution of APS (mixed) An amount corresponding to 0.158% by mass of the monomer) was dropped into the flask over 2 hours and polymerized. 2.5 hours after the start of the polymerization, the temperature in the flask was raised to 80 ° C., kept for 2 hours, cooled, neutralized with ammonia water to adjust the pH to 7, filtered through a 300 mesh wire mesh, and blue An aqueous dispersion of white VdF seed polymer particles (average particle size 210 nm) of the present invention was produced.

  The obtained VdF seed polymer particles had a fluorine content of 18% by mass based on elemental analysis and an acrylic polymer content of 70% by mass. Moreover, MFR (250 degreeC, 10 kg) was 8.2 g / 10min.

  A white coating composition and a clear coating composition were prepared in the same manner as in Example 1 except that the aqueous dispersion of VdF-based seed polymer particles obtained above was used, and various characteristics were examined. The results are shown in Table 1.

Example 6
98 g of the VdF copolymer aqueous dispersion obtained in Production Example 1 was charged into a 2 L four-necked flask equipped with a stirring blade, a cooling tube, and a thermometer, In order to ensure stability, 707SF (manufactured by Nippon Emulsifier Co., Ltd.) as a surfactant is 3.3% by mass with respect to the solid content of the VdF copolymer, and RMA-450M (manufactured by Nippon Emulsifier Co., Ltd.) is used as a VdF system. 3 mass% was added with respect to copolymer solid content. Separately, MMA, BA, and AA 63.2 / 35.7 / 1.1 (mol% ratio) mixed monomer (98 g) and dodecyl mercaptan 0.09 g (0.08 g of mixed monomer) (A quantity corresponding to mass%) was prepared, and this was dropped into the flask over 30 minutes and further stirred for 1 hour. Then, it heated in the water bath and raised the temperature in this flask to 75 degreeC. Here, 17 ml of a 1% aqueous solution of APS (an amount corresponding to 0.158% by mass of the mixed monomer) was dropped into the flask over 2 hours and polymerized. 2.5 hours after the start of the polymerization, the temperature in the flask was raised to 80 ° C., held for 2 hours, cooled, neutralized with aqueous ammonia to adjust the pH to 7, filtered through a 400 mesh wire mesh, and blue An aqueous dispersion of white VdF seed polymer particles (average particle size 210 nm) of the present invention was produced.

  The obtained VdF seed polymer particles had a fluorine content of 18% by mass based on elemental analysis and an acrylic polymer content of 70% by mass. Moreover, MFR (250 degreeC, 10 kg) was 23 g / 10min.

  A white coating composition and a clear coating composition were prepared in the same manner as in Example 1 except that the aqueous dispersion of VdF-based seed polymer particles obtained above was used, and various characteristics were examined. The results are shown in Table 1.

Comparative Example 1
(Production of aqueous dispersion of VdF seed polymer for comparison)
Into a 2 L four-necked flask equipped with a stirring blade, a cooling tube, and a thermometer, 90 g of the aqueous VdF copolymer dispersion obtained in Production Example 1 was charged, and the seed particles used for seed polymerization were charged into the flask. In order to ensure stability, 707SF (manufactured by Nippon Emulsifier Co., Ltd.) as a surfactant is 2.6% by mass with respect to the solid content of the VdF copolymer, and RMA-450M (manufactured by Nippon Emulsifier Co., Ltd.) is used as a VdF system. 3 mass% was added with respect to copolymer solid content. The mixture was heated in a water bath with stirring, and the temperature in the flask was raised to 75 ° C. Separately, a mixed monomer (98 g) of MMA, BA, and AA in 63.2 / 35.7 / 1.1 (mole% ratio) and 0.5 g of dodecyl mercaptan (to 0.5% by mass of the mixed monomer) Corresponding amount), 16 ml of a 1% aqueous solution of APS (an amount corresponding to 0.158% by mass of the mixed monomer) was prepared, and this was dropped into the flask over 2 hours to initiate polymerization. . 2.5 hours after the start of the polymerization, the temperature in the flask was raised to 80 ° C., kept for 2 hours, cooled, neutralized with ammonia water to adjust the pH to 7, filtered through a 300 mesh wire mesh, and blue An aqueous dispersion of white VdF seed polymer particles (average particle size 230 nm) for comparison was produced.

  The resulting VdF seed polymer particles had a fluorine content of 18% by mass and an acrylic polymer content of 70% by mass. Moreover, MFR (250 degreeC, 10 kg) was 1800 g or more / 10min.

  A white coating composition and a clear coating composition were prepared in the same manner as in Example 1 except that the aqueous dispersion of VdF-based seed polymer particles obtained above was used, and various characteristics were examined. The results are shown in Table 1.

  From Table 1, it can be seen that water resistance and gloss are improved by adjusting the amount of chain transfer agent used in the production process of the aqueous dispersion of the VdF seed polymer and increasing the molecular weight.

Claims (4)

It is obtained by seed polymerization of a monomer containing an acrylic monomer using vinylidene fluoride copolymer particles containing a vinylidene fluoride monomer as seed particles, and (1) containing an acrylic monomer unit The amount is 50% by weight or more,
(2) A fluororesin aqueous dispersion containing a vinylidene fluoride seed polymer having a melt flow rate (250 ° C., 10 kg) of 30 g / 10 min or less. The aqueous dispersion according to claim 1, wherein the vinylidene fluoride copolymer comprises a vinylidene fluoride unit and a tetrafluoroethylene unit. The aqueous dispersion according to claim 1, wherein the vinylidene fluoride copolymer comprises a vinylidene fluoride unit, a tetrafluoroethylene unit, and a chlorotrifluoroethylene unit. The fluororesin aqueous coating composition containing the fluororesin aqueous dispersion of any one of Claims 1-3.