JP2012136640A - Method for production of composition for fluorine-containing powder coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for production of a composition for a fluorine-containing powder coating material, in which the resin powders do not bind each other even when using the thermoplastic resin powder including a fluorine-containing copolymer.SOLUTION: The method for production of a powder coating material composition includes removing a solvent from a mixture of the powder of a thermosetting resin containing the fluorine-containing copolymer, a flaky pigment and the solvent. The solvent contains at least one of 1,1,2,2-tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane and 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorohexane.

Description

  The present invention relates to a method for producing a fluorine-containing powder coating composition.

  The demand for powder coatings is increasing for automobile parts, electrical appliances, furniture, machine tools, office equipment, toys, etc. as a low-pollution coating that does not use organic solvents. In addition to being a low-pollution type paint, the coating with powder paint is thick, and it is not necessary to repaint it many times like conventional solvent-type paints. The painting time can be shortened. Furthermore, since the paint does not contain a solvent, it has an advantage of low environmental load. The color variations required for powder coatings are also required to be similar to those of conventional coatings, and the demand for metallic colors is increasing in recent years, mainly in building interior and exterior materials.

  As a method for producing a metallic powder coating as described above, a melt blend method in which a flaky pigment is sufficiently kneaded with a resin or a colored pigment in advance by a melting method and then pulverized to form a powder, a resin powder and a flaky pigment There are known dry blending methods in which and are mixed and applied.

However, in the melt blending method, the flake pigment is destroyed at the time of kneading and the intended design cannot be obtained. In particular, aluminum flakes that give a metallic color design cause remarkable destruction of flake pigments. In the dry blend method, the flake pigment and resin are not uniformly attached to the object to be coated due to the difference in capacitance during coating, or when the powder paint is recovered and reused. There is a problem that the mixing ratio of the powder cannot be maintained.
As a method for solving the above-mentioned problem, a method has been proposed in which a thermosetting resin powder is dispersed together with a flaky pigment in a solvent that does not dissolve the thermosetting resin powder, and then the solvent is volatilized and removed while stirring (patent) See reference 1.)

  However, when the fluorine-containing copolymer is contained as the thermosetting resin powder, the fluorine-containing copolymer can be selected even if a solvent that does not dissolve the thermoplastic resin powder exemplified in Patent Document 1 is selected. In the case of a solvent that swells significantly, it has been found that the particles of the thermoplastic resin powder are bound to each other and cannot be used as a powder coating material after the solvent is volatilized.

JP 2010-189597 A

  An object of the present invention is to provide a method for producing a composition for a fluorine-containing powder coating material in which binding between resin powders does not occur even when a thermoplastic resin powder containing a fluorine-containing copolymer is used. To do.

The present invention employs the following configuration in order to solve the above problems.
[1] In a method for producing a powder coating composition, in which a solvent is removed from a mixture containing a thermosetting resin powder containing a fluorinated copolymer, a flaky pigment and a solvent, the solvent is 1, 1, 2 , 2-tetrafluoro-1- (2,2,2-trifluoroethoxy) ethane and 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluoro A method for producing a composition for a fluorine-containing powder coating material, which is a solvent containing at least one of hexane.
[2] The solvent is 1,1,2,2-tetrafluoro-1- (2,2,2-trifluoroethoxy) ethane and 1,1,1,2,2,3,3 in the total mass of the solvent. , 4, 4, 5, 5, 6, 6-tridecafluorohexane The method for producing a fluorine-containing powder coating composition according to [1], which is a solvent containing 90% by mass or more.
[3] The method for producing a composition for a fluorine-containing powder coating material according to [1] or [2], wherein the mixture further contains a hydrogenated terpene resin.
[4] The method for producing a fluorine-containing powder coating composition according to any one of [1] to [3], wherein the content of the fluorine-containing copolymer in the thermoplastic resin powder is 50% by mass or more.
[5] The fluorine-containing copolymer according to any one of [1] to [4], wherein the fluorine-containing copolymer is a copolymer having a polymer unit based on at least one monomer of chlorotrifluoroethylene and tetrafluoroethylene. A method for producing a composition for fluorine-containing powder coatings.
[6] Any of [1] to [5], wherein the fluorinated copolymer is a copolymer having a polymer based on at least one monomer selected from alkyl vinyl ethers and alkyl vinyl esters. The manufacturing method of the composition for fluorine-containing powder coating materials of description.

  According to the present invention, even when a thermoplastic resin powder containing a fluorinated copolymer is used, a composition for a fluorinated powder coating material can be produced without causing binding between particles of the powder. it can.

<Fluorine-containing powder coating composition>
In the composition for fluorine-containing powder coatings obtained by the production method of the present invention, the flaky pigment is immobilized on the surface of a thermosetting resin powder containing a fluorine-containing copolymer. Here, the thermosetting resin powder having the flake pigment immobilized on the surface means a form in which a single to plural flake pigments adhere to the surface of one thermosetting resin powder. This is clearly distinguished from a form in which a plurality of thermosetting resin powders are combined. However, this does not exclude a composition in which a plurality of thermosetting resin powders are bonded to each other or a composition for powder coating containing a thermosetting resin powder in which only one flake pigment is bonded to the surface.

  In addition, the coating film formed from the fluorine-containing powder coating composition obtained by the production method of the present invention can have a unique design by containing a flake pigment having a specific shape. it can. For example, when a metal pigment such as aluminum flakes is included, a metallic color can be developed on the coating film. Furthermore, since this coating film contains a fluorine-containing copolymer, it is excellent in weather resistance and chemical resistance.

<Thermosetting resin powder>
The thermoplastic resin powder in the present invention contains a fluorine-containing copolymer. In the thermoplastic resin powder of the present invention, (1) a fluorine-containing copolymer having thermosetting properties, (2) a fluorine-containing copolymer having a crosslinkable group, and a crosslinking agent that reacts with the crosslinkable group And (3) a fluorine-containing copolymer and a thermosetting resin other than the fluorine-containing copolymer are preferable, and the mode (2) is most preferable.

  The thermosetting resin in the case of (3) is not particularly limited as long as it is a resin other than the fluorine-containing copolymer and has thermosetting properties, and the resin itself may have thermosetting properties and may be crosslinked. A combination of a resin having a functional group and a crosslinking agent that reacts with the crosslinkability may be used. Examples of such a thermosetting resin include resins described in JP 2010-189597 A. As the combination of the crosslinkable group and the crosslinking agent in the resin having a crosslinkable group, a known one can be used.

  Moreover, the thermosetting resin powder of this invention can also contain various coloring agents. Examples of such colorants include quinacridone, diketopyrrolopyrrole, isoindolinone, indanthrone, perylene, perinone, anthraquinone, dioxazine, benzimidazolone, triphenylmethanequinophthalone, anthrapyrimidine, chrome lead, phthalocyanine, halogen Phthalocyanines, azo pigments (azomethine metal complexes, condensed azo, etc.), titanium oxide, carbon black, iron oxide, copper phthalocyanine, condensed polycyclic pigments, and the like. Although the blending amount of these colorants varies depending on the type, it is desirable to set the colorant within a range that does not impair the effects brought about by the flake pigment of the present invention and does not impair the smoothness of the coating film surface.

  The thermosetting resin powder of the present invention can also contain the following additives as required in addition to the various additive components listed above. Examples of such additives include various fillers such as bentonite, alumina white, calcium carbonate, barium sulfate and talc, various fluidity modifiers such as silica, alumina and aluminum hydroxide, various streams such as acrylic oligomers and silicones. Examples thereof include spreading agents, various antifoaming agents such as benzoin, waxes, coupling agents, antioxidants, magnetic powders, stabilizers, ultraviolet absorbers, leveling agents, thickeners, and antisettling agents. Thus, the thermosetting resin powder of the present invention can contain various additives and various functional materials as described above.

The 50% volume average particle size of such a thermosetting resin powder is not particularly limited, but is usually preferably about 15 to 100 μm, particularly preferably 20 to 60 μm. When the 50% volume average particle size is less than 15 μm, the particle size distribution substantially increases the number of particles of 5 μm or less, and it becomes difficult to uniformly mix with the flaky pigment, and the thermosetting resin powder tends to aggregate. In some cases, it becomes difficult to apply uniformly during powder coating. On the other hand, when the 50% volume average particle diameter exceeds 100 μm, the smoothness of the coating film surface may be hindered and a good appearance may not be obtained.
Such an average particle diameter can be determined by a known particle size distribution measurement method such as a laser diffraction method, a micromesh sieve method, or a Coulter counter method.

  In order to manufacture such thermosetting resin powder, for example, various additives such as a resin, a curing agent, and a filler to be added as necessary are prepared as raw materials, and these raw materials are first mixed with a mixer or a blender. Dry blend using a mixer. After dry blending, the raw materials are melt-kneaded with a kneader and cooled. Next, the thermosetting resin powder of the present invention can be obtained by pulverizing the cooled melt-kneaded product using a machine or an airflow type pulverizer, and then classifying using an airflow type classifier. . In addition to this method, the thermosetting resin powder can be produced by, for example, a spray drying method or a polymerization method.

<Fluorine-containing copolymer>
The fluorine-containing copolymer in the present invention is not particularly limited as long as it is a copolymer having a fluorine atom, but is preferably a copolymer having a polymer unit based on a fluoroolefin.
Examples of the fluoroolefin include chlorotrifluoroethylene and tetrafluoroethylene, and among these, chlorotrifluoroethylene and tetrafluoroethylene are more preferable.

  When the fluorine-containing copolymer has a crosslinkable group, it is preferable to copolymerize a monomer having a crosslinkable group with a fluoroolefin. The crosslinkability is preferably a hydroxyl group, a carboxyl group, an epoxy group, or an exetan group, and more preferably a hydroxyl group or a carboxyl group. As such a monomer having a crosslinkable group, a compound having a double bond and a crosslinkable group is preferable, and vinyl esters, vinyl ethers, and allyl ethers are particularly preferable. Specifically, when the crosslinkable group is a hydroxyl group, examples thereof include hydroxybutyl vinyl ether and hydroxyethyl vinyl ether. In the case where the crosslinkable group is a carboxyl group, a method of adding a carboxyl group using an acid anhydride after producing a polymer with a hydroxyl group-containing copolymer can be mentioned.

  When the fluorine-containing copolymer has a crosslinkable group, the crosslinker used in combination is not particularly limited as long as it is a crosslinker that reacts with the crosslinkable group. For example, when the crosslinkable group is a hydroxyl group, a polyisocyanate curing agent and melamine are preferable. When the crosslinkable group is a carboxyl group, epoxy and hydroxyalkylamide are preferable.

  In the production process of thermoplastic resin powder, when there is a process of adding heat or generating heat such as kneading or pulverization, the reaction temperature between the crosslinkable group and the crosslinking agent is the highest in the production process of thermoplastic resin powder. It is preferably higher than the temperature. Specifically, the temperature is preferably −20 ° C. or higher, more preferably −30 ° C. or higher, than the temperature of the step of applying heat.

  As a combination of such a crosslinkable group and a crosslinking agent, a combination of a hydroxyl group and a polyisocyanate curing agent or a block polyisocyanate curing agent is preferable.

<Flake pigment>
The flaky pigment typified by aluminum flakes may be in the form of a paste in which the flaky pigment is dispersed in an organic solvent, or in the form of a resin solidified in a pellet form. Further, it may be in a dry powder form.
When using a paste-like flaky pigment, the paste-like flaky pigment may be used as it is, and an organic solvent in which the flaky pigment is dispersed may be contained as a part of the solvent in the production method of the present invention. Good. However, mineral spirits, toluene, ethyl acetate, butyl acetate, isoparaffin, etc. are used as the organic solvent for dispersing the flake pigment, and such an organic solvent dissolves the fluorine-containing copolymer used in the present invention. Or it swells. Therefore, when using a paste-like flaky pigment, it is preferable to replace the organic solvent with the solvent used in the present invention in advance.

  As such a solvent replacement method, for example, a paste containing such an organic solvent and flake pigment (that is, a commercially available flake pigment in a paste state) is washed with a solvent used in the solvent dispersion step using a filtration device. And a method of recovering the flaky pigment in a state of being dispersed in the solvent used in the solvent dispersion step by dispersing or filtering such a paste in the solvent used in the solvent dispersion step. Can be mentioned.

<Solvent>
In the present invention, a thermosetting resin powder containing a fluorinated copolymer, a flake pigment, and a solvent are mixed. The solvent used in the present invention is 1,1,2,2-tetrafluoro-1- (2,2,2-trifluoroethoxy) ethane, or 1,1,1,2,2,3,3,4. , 4, 5, 5, 6, 6-tridecafluorohexane, but may contain other solvents other than these solvents as long as the effects of the present invention are not impaired.
The solvent in the present invention is 1,1,2,2-tetrafluoro-1- (2,2,2-trifluoroethoxy) ethane and 1,1,1,2,2,3,3,4,4, It is preferable to contain at least one of 5,5,6,6-tridecafluorohexane in an amount of 90% by mass or more, more preferably 95% by mass or more, and most preferably composed of at least one of these solvents. .

1,1,2,2-tetrafluoro-1- (2,2,2-trifluoroethoxy) ethane and 1,1,1,2,2,3,3,4,4,5,5,6, If the content of at least one of 6-tridecafluorohexane is within this range, the powder coating particles cannot be separated from other mixed components by dissolution of the powder coating particles, or the powder coating shape cannot be maintained by melting without melting. Problems are less likely to occur.
In the present invention, in particular, 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorohexane is used in the conventional bonded method using a binder. Since this hydrogenated terpene phenol resin dissolves and does not dissolve the fluorine-containing copolymer, it can be suitably used in the bonded method using a binder.

<Method for producing composition for fluorine-containing powder coating material>
The production method of the present invention is a method for producing a powder coating composition in which a solvent is removed from a mixture containing a thermosetting resin powder containing a fluorinated copolymer, a flaky pigment, and a solvent. , 1,2,2-tetrafluoro-1- (2,2,2-trifluoroethoxy) ethane and 1,1,1,2,2,3,3,4,4,5,5,6,6 -A solvent containing at least one of tridecafluorohexane.

The production method of the present invention includes a mixing step of mixing a thermosetting resin powder containing a fluorinated copolymer, a flaky pigment, and a solvent, and a solvent removing step of removing the solvent from the mixture obtained in the mixing step. It is preferable.
In the mixing step, the thermosetting resin powder containing the fluorinated copolymer, the flaky pigment, and the solvent are mixed. The solid content concentration of the mixture is preferably 50 to 90% by mass, particularly 70. It is more preferable to set it to -85 mass%. When the solid content concentration of the mixture is within this range, uniform mixing of the flaky pigment and the thermosetting resin powder is good, and less energy and time are required for removing the solvent, so that production efficiency is reduced. Good.

In the solvent removal step, the solvent is removed from the mixture, and the flaky pigment is immobilized on the surface of the thermosetting resin powder containing the fluorine-containing copolymer.
In the solvent removal step, stirring is continued until the solvent contained in the mixture is volatilized and the whole is pulverized. After the solvent is completely removed, the powder coating material of the present invention is classified using a screen. A composition can be obtained. In removing the solvent, it is preferable to volatilize and remove the solvent while stirring the mixture. By removing the solvent while stirring, the flaky pigment is uniformly aggregated on the surface of the thermosetting resin powder, and a thermosetting resin powder having the flaky pigment fixed on the surface is obtained. In the evaporation step, it is preferable to remove the solvent by volatilizing it with vacuum suction.

  In the solvent removal step, the mixture is preferably stirred in the range of −5 ° C. to 50 ° C. In particular, it is more preferable to hold the mixture at a temperature of 0 ° C. or higher, and it is more preferable to hold the mixture at a temperature of 40 ° C. or lower. When the said temperature exceeds 50 degreeC, the coupling | bonding of thermosetting resin powder is accelerated | stimulated and there exists a possibility of blocking. In this case, the agglomerated particles (blocked particles) can be pulverized by a physical pulverization method such as a jet mill. In this case, the thermosetting resin powder particles themselves may be destroyed. On the other hand, if the temperature is lower than −5 ° C., it takes a long time to volatilize the solvent, which is not practical. That is, the evaporation step of the present invention is a temperature at which the thermosetting resin powders do not block each other (that is, a temperature not higher than the melting temperature of the thermosetting resin powder) and the temperature at which the solvent is efficiently volatilized. Is preferably performed.

<Application>
Compositions for fluorine-containing powder coatings obtained by the production method of the present invention include, for example, building finishing materials, automobiles, ships, mobile objects such as aircraft, office supplies, household goods, sports equipment, building materials, weak electricity, heavy electricity It can be used for road materials such as equipment, pillars and signals, signs, handrails and guardrails.

Examples of the present invention are shown below, but the present invention is not limited to the following examples.
<Production of fluorine-containing copolymer>
A stainless steel pressure resistant reactor with an internal volume of 2.5 L equipped with a stirrer was charged with 503 g of xylene, 558 g of cyclohexyl vinyl ether, 145 g of hydroxybutyl vinyl ether, 12 g of calcium carbonate and 7 g of perbutyl pivalate, and nitrogen. The gas replacement by was performed, and dissolved oxygen in the reactor was removed.

  Next, 660 g of CTFE was introduced, the temperature was gradually raised to 65 ° C., and the reaction was continued for 10 hours while maintaining the temperature at 65 ° C. After 10 hours, the reactor was cooled with water to obtain a reaction solution. After cooling the obtained reaction liquid to room temperature, unreacted raw materials were purged and filtered to remove undissolved substances to obtain a fluorinated copolymer solution having a solid content concentration of 65% by mass. The obtained solution was dried under reduced pressure to obtain a fluorinated copolymer having a hydroxyl value of 50 mgKOH / g and a Tg of 50 ° C.

<Manufacture of thermosetting resin powder>
52 parts by mass of the fluorine-containing copolymer, 14 parts by mass of an isocyanate resin “Vestagon B-1530 manufactured by Creanova Co., Ltd., trade name) blocked with ε-caprolactam, 0.4 parts by mass of benzoin, acrylic acid oligomer High-speed mixer containing 1 part by mass of a system leveling agent “BYK-364P (product name, manufactured by BYK-Chemie)”, 28 parts by mass of titanium dioxide “Titone D-918D” and 0.1 part by mass of dibutyltin dilaurate And mixed for 1 minute. And it knead | mixes using the biaxial kneader (Prism company) temperature-controlled at 120 degreeC, and after cold-rolling the discharged kneaded material with a cooling roll, the obtained plate-like mixture obtained is crushed. Then, the mixture was pulverized using a pin mill and classified with a mesh having an opening of 100 μm to obtain a thermoplastic resin powder (50% volume average particle size: 35 μm) containing a fluorine-containing copolymer.

<Experimental example 1>
5 g of the obtained thermosetting resin powder containing the fluorinated copolymer was put into a container with a 50 ml capacity lid, and 0.25 aluminum powder (STANDART Aluminum Powder PCR901: trade name of ECKART) was added as a flake pigment. . Thereafter, 4 g of a solvent was added, and the container was sealed. The container was shaken after being left for 1 hour, and the state of the thermosetting powder coating was observed (the state after 1 hour). Thereafter, the solvent was evaporated by drying in a vacuum vessel at 30 ° C. and 400 Pa for 5 hours, and the state of the remaining powder was observed (the state after volatilization).

[Evaluation of state]
(State after 1 hour)
○: The thermosetting powder coating in the container is maintained in powder form. Δ: The thermosetting powder coating in the container is not maintained in powder form and is melted (the solvent and the powder coating are separated. ing)
X: The thermosetting powder coating in the container is dissolved in a solvent to form a suspension (state after solvent volatilization)
○: Maintaining the powder form ×: A lump Table 1 shows the experimental results using various solvents.

<Experimental example 2>
Solvent 1,1,2,2-tetrafluoro-1- (2,2,2-trifluoroethoxy) ethane, 1,1,1,2,2,3,3,4,4 used in Experimental Example 1 , 5,5,6,6-tridecafluorohexane, n-hexane, n-heptane, dichloropentafluoropropane 10 g each of hydrogenated terpene resin (YS Polyester TH-130: trade name of Yasuhara Chemical Co., Ltd.) 075 g was added and the state was observed.
As a result, hydrogenated terpene resins were 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorohexane, n-hexane, n-heptane, dichloropenta. Dissolved in fluoropropane. On the other hand, 1,1,2,2-tetrafluoro-1- (2,2,2-trifluoroethoxy) ethane was not completely dissolved.

  As described above, in the thermosetting resin powder powder coating containing the fluorine-containing copolymer, 1,1,2,2-tetrafluoro-1- (2,2,2-trifluoroethoxy) ethane, 1, 1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorohexane does not dissolve the thermosetting powder coating containing a fluorine-containing copolymer as a binder, and flakes Particles could be dispersed. In 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorohexane, a hydrogenated terpene resin used as a binder for flake pigments is used. It can be dissolved, and can also be used in a flaky pigment fixing step using a binder.

Solvent A: 1,1,2,2-tetrafluoro-1- (2,2,2-trifluoroethoxy) ethane Solvent B: 1,1,1,2,2,3,3,4,4,5 , 5,6,6-Tridecafluorohexane

Claims (6)

  In the method for producing a composition for powder coating, in which the solvent is removed from the mixture containing the thermosetting resin powder containing the fluorinated copolymer, the flaky pigment and the solvent, the solvent is 1,1,2,2- At least of tetrafluoro-1- (2,2,2-trifluoroethoxy) ethane and 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorohexane The manufacturing method of the composition for fluorine-containing powder coating materials characterized by being a solvent containing one side.   The solvent is 1,1,2,2-tetrafluoro-1- (2,2,2-trifluoroethoxy) ethane and 1,1,1,2,2,3,3,4, in the total mass of the solvent The method for producing a fluorine-containing powder coating composition according to claim 1, which is a solvent containing 90% by mass or more of at least one of 4,5,5,6,6-tridecafluorohexane.   The method for producing a fluorine-containing powder coating composition according to claim 1 or 2, wherein the mixture further comprises a hydrogenated terpene resin.   The method for producing a fluorine-containing powder coating composition according to any one of claims 1 to 3, wherein the content of the fluorine-containing copolymer in the thermoplastic resin powder is 50% by mass or more.   The fluorine-containing copolymer for a fluorine-containing powder coating according to any one of claims 1 to 4, wherein the fluorine-containing copolymer is a copolymer having a polymer unit based on at least one monomer of chlorotrifluoroethylene or tetrafluoroethylene. A method for producing the composition.   The fluorine-containing copolymer according to any one of claims 1 to 5, wherein the fluorine-containing copolymer is a copolymer having a polymer based on at least one monomer selected from alkyl vinyl ethers and alkyl vinyl esters. A method for producing a powder coating composition.