JP2004027115A - Composition for fluororesin-containing powder coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for a fluororesin-containing powder coating which gives a coating film having good weatherability and a designed embossed pattern on its surface. <P>SOLUTION: The composition comprises a fluororesin (A) having hydroxy groups, a polyisocyanate curing agent (B) containing an uretdione bonding and a blocked polyisocyanate curing agent (C), wherein 10-40 parts by mass of (C) is included for 100 parts by mass of (B). <P>COPYRIGHT: (C)2004,JPO

Description

【００４４】
【発明の効果】
本発明によれば、フッ素樹脂の卓越した耐候性能を保持したままで、表面に布地状の意匠性を有する凹凸模様を有し、高級感を与える塗膜を形成することができる。さらに、本発明の含フッ素樹脂粉体塗料用組成物からなる塗膜は耐衝撃性、基材への密着性も良好であり、塗料として優れた性能を有している。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a composition for a fluorine-containing resin powder coating.
[0002]
[Prior art]
Since powder paints are solvent-free, their range of use has expanded due to the recent increase in environmental protection awareness. Among these, the fluorine-containing resin powder coating is a coating that is expected to increase in use due to the maintenance-free wind due to the weather resistance performance that the fluorine-containing resin has specifically. Along with the expansion of such application fields, there are increasing uses for which the coating film is required to have design properties.
[0003]
Japanese Patent Application Laid-Open No. 5-78605 describes that a coating film with an uneven pattern having design properties can be formed from a thermosetting powder coating kneaded with cellulose ester. However, when this method is applied to a fluorine-containing resin powder coating, a component having poor weather resistance is introduced, and the excellent weather resistance of the fluorine-containing resin powder coating is impaired. In addition, the kneading of the cellulose ester significantly reduces the surface tension when the paint is melted. As a result, it is known that when a paint kneaded with cellulose ester is mixed in a powder paint in which cellulose ester is not kneaded, coating surface defects such as repellency are given. Therefore, it is necessary to take measures such as isolating the production line so that the paint kneaded with cellulose ester and the paint not kneaded are mixed after the powder paint is manufactured.
[0004]
[Problems to be solved by the invention]
The present invention has been made to solve the above-described drawbacks, and an object of the present invention is to provide a composition capable of forming a concavo-convex pattern having design properties without impairing the weather resistance.
[0005]
[Means for Solving the Problems]
The present invention contains a fluorine-containing resin (A) having a hydroxyl group, a polyisocyanate curing agent (B) having a uretdione bond, and a blocked polyisocyanate curing agent (C). Is contained in an amount of 10 to 40 parts by mass, and a fluorine-containing resin powder coating composition is provided.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The fluorine-containing resin (A) having a hydroxyl group in the present invention preferably has a fluorine-containing polymer unit (x) obtained by polymerizing a fluorine-containing monomer (X) having an ethylenically unsaturated group.
[0007]
Examples of the fluorine-containing monomer (X) include tetrafluoroethylene, hexafluoropropylene, perfluorobutene-1, perfluorohexene-1, perfluorononene-1, chlorotrifluoroethylene, trifluoroethylene, and vinylidene fluoride. Perfluoro (methyl vinyl ether), perfluoro (ethyl vinyl ether), perfluoro (propyl vinyl ether), perfluoro (alkyl vinyl ether) such as perfluoro (heptyl vinyl ether), (perfluoromethyl) ethylene, And (perfluoroalkyl) ethylenes such as (perfluorobutyl) ethylene. This fluorine-containing monomer (X) may be used independently and may use 2 or more types together. The fluorine-containing monomer (X) is preferably a fluoroolefin having 2 to 3 carbon atoms, particularly fluoroethylenes such as tetrafluoroethylene, chlorotrifluoroethylene, and vinylidene fluoride.
[0008]
Although any known method can be adopted as a method for introducing a hydroxyl group into the fluororesin (A) in the present invention, those having a polymer unit (y) having a hydroxyl group other than the polymer unit (x) are preferred. The polymerization unit (y) is preferably obtained by polymerizing the hydroxyl group-containing polymerizable monomer (Y), but may be a monomer having a functional group that can be converted to a hydroxyl group after polymerization.
[0009]
Examples of the hydroxyl group-containing polymerizable monomer (Y) include alkenyl alcohols such as allyl alcohol, hydroxy compounds such as (2-hydroxyethyl) vinyl ether, (3-hydroxypropyl) vinyl ether, (4-hydroxybutyl) vinyl ether, and hydroxycyclohexyl vinyl ether. Vinyl ethers, hydroxy allyl ethers such as (2-hydroxyethyl) allyl ether, (3-hydroxypropyl) allyl ether, (4-hydroxybutyl) allyl ether, hydroxycyclohexyl allyl ether, (2-hydroxyethyl) acrylate, ( 2-hydroxyethyl) methacrylates such as methacrylate, vinyl hydroxyacetate, vinyl hydroxyisobutyrate, vinyl hydroxypropionate , Esters of hydroxyalkyl carboxylic acids such as vinyl hydroxybutyrate, vinyl hydroxyvalerate, vinyl hydroxycyclohexylcarboxylate and vinyl alcohol, hydroxyethyl allyl ester, hydroxypropyl allyl ester, hydroxybutyl allyl ester, hydroxyisobutyl allyl ester, hydroxy And hydroxyalkyl allyl esters such as cyclohexyl allyl ester.
[0010]
The fluororesin (A) in the present invention may have a polymerization unit (z) other than the polymerization unit (x) and the polymerization unit (y). The polymerized unit (z) is a polymerized unit based on a polymerizable monomer (Z) other than the fluorine-containing monomer (X) and the polymerizable monomer (Y) having a hydroxyl group. As the polymerizable monomer (Z), a polymerizable monomer in which a hydrogen atom bonded to a carbon atom forming an ethylenically unsaturated group is not substituted with a fluorine atom is preferable. Examples of the polymerizable monomer (Z) include polymerizable monomers having a polymerizable site such as a (meth) acryloyl group, a vinyl group, an allyl group, and an isopropenyl group. As the polymerizable monomer (Z), vinyl ethers, olefins, allyl ethers, vinyl esters, allyl esters, (meth) acrylic acid esters, isopropenyl ethers, isopropenyl esters, crotonic acid esters, And other polymerizable monomers. Especially, the compound which has a C1-C15 linear, branched or cyclic alkyl group is preferable.
[0011]
The polymerizable monomer (Z) may be used alone or in combination of two or more. Specific examples of the polymerizable monomer (Z) include the following compounds.
Alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether, chloroethyl vinyl ether, alkyl isopropenyl ethers such as methyl isopropenyl ether, fatty acid isopropenyl esters, ethylene, propylene, 1-butene, Olefins such as isobutylene and cyclohexene, styrene monomers such as styrene and α-methylstyrene, alkyl allyl ethers such as methyl allyl ether, ethyl allyl ether, butyl allyl ether, cyclohexyl allyl ether, vinyl acetate, vinyl propionate, Vinyl butyrate, vinyl isobutyrate, vinyl valerate, vinyl hexanoate, vinyl octoate, Veova 9 and Veova 0 (product name of vinyl ester of branched fatty acid having 9 or 10 carbon atoms, manufactured by Shell Chemical Co., Ltd.), fatty acid vinyl esters such as vinyl versatate, fatty acid allyl esters such as allyl propionate, allyl acetate, (meth) (Meth) acrylic acids such as methyl acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) acrylic amides such as (meth) acrylic amide, acrylonitrile, Cyano group-containing monomers such as 2,4-dicyanobutene-1, dienes such as isoprene and butadiene, halogenated olefins such as vinyl chloride and vinylidene chloride, polymerizable monomers having a polyoxyalkylene chain having a molecular weight of 100 to 3000, etc. Is mentioned.
[0012]
Among these, the polymerizable monomer (Z) includes polymerizable monomers selected from alkyl vinyl ethers, fatty acid vinyl esters, alkyl allyl ethers, fatty acid allyl esters, alkyl isopropenyl ethers, and fatty acid isopropenyl esters. Of these, alkyl vinyl ethers are preferred.
[0013]
The hydroxyl value of the fluororesin (A) in the present invention is preferably 10 mgKOH / g or more because it can provide sufficient impact resistance to the coating film obtained from the fluororesin powder coating composition of the present invention. Since the softness | flexibility of this coating film can be maintained, 200 mgKOH / g or less is preferable. Particularly preferred is 25 to 200 mg KOH / g.
[0014]
The glass transition temperature (Tg) of the fluororesin (A) measured by a differential thermal analyzer (DSC) is the transparency of the coating film obtained from the fluororesin powder coating composition of the present invention, and the solvent resistance. 30 degreeC or more is preferable from the viewpoint of favorable property, and 80 degreeC or less is preferable from being able to maintain transparency of this coating film favorable. 35-60 degreeC is especially preferable.
[0015]
As the polyisocyanate curing agent (B) having a uretdione bond in the present invention, isophorone diisocyanate (hereinafter referred to as IPDI) or hexamethylene diiaocyanate (hereinafter referred to as HMDI) is used as a main skeleton and the isocyanates are uretdione bonds. And the compounds coupled by the above. As such polyisocyanates having a uretdione bond, Clenova BF1540 (trade name, manufactured by Degussa), Clelan VPLS 2147, VPLS 2347 (trade name, manufactured by Bayer) and the like are commercially available.
[0016]
As the blocked polyisocyanate curing agent (C) in the present invention, a known blocked polyisocyanate commercially available for powder coating can be used. Specifically, compounds in which isocyanate is blocked with epsilon caprolactam (hereinafter referred to as E-CAP), methyl ethyl ketone oxime, methyl isobutyl ketone oxime, or triazine with IPDI or 4,4′-methylenebis (cyclohexyl isocyanate) as the main skeleton. , Compounds in which the blocking moiety is a uretdione bond, and the like. As such blocked polyisocyanates, Clenova B1530, B1065 (trade name, manufactured by Degussa), TPLS2007, FGB4553, Clerant Ui (trade name, manufactured by Bayer), Alcure 4470, 4430, 4431, 4450 (trade name, McWater) Etc.).
[0017]
The blocked polyisocyanate curing agent (C) is contained in an amount of 10 to 40 parts by mass with respect to 100 parts by mass of the polyisocyanate curing agent (B) having a uretdione bond. If it is less than 10 parts by mass, impact resistance, adhesion and weather resistance are not exhibited, which is not preferable. If it exceeds 40 parts by mass, irregularities are not formed on the surface of the coating film.
[0018]
According to the present invention, a concavo-convex pattern having design properties (hereinafter, also referred to as a chijimi pattern) can be formed on the surface of the coating film, and the degree of the chijimi pattern (depending on the depth and size of the individual irregularities). Can be adjusted by the ratio of the polyisocyanate curing agent (B) having a uretdione bond and the blocked polyisocyanate curing agent (C). Although these reasons are not necessarily clear, it is considered that the compatibility between the fluorine-containing resin (A) having a hydroxyl group and the polyisocyanate curing agent (B) having a uretdione bond is extremely poor and causes phase separation during the curing reaction. It is done. The blocked polyisocyanate curing agent (C) changes the phase separation state by improving the compatibility between the fluorine-containing resin (A) and the polyisocyanate curing agent (B), and adjusts the degree of the Chijimi pattern. It is thought that it plays a role of complementing the non-uniform state of hardening due to separation.
[0019]
In the polyisocyanate curing agent (B), the ratio of the isocyanate group equivalent of (B) to the hydroxyl equivalent of the fluororesin (A) (hereinafter referred to as NCO / OH) is 0.6 to 1.2. It is preferable that it is contained in such a ratio. By being in this range, a sufficient Chijimi pattern can be formed. The ratio of the total of the isocyanate group equivalents of (B) and (C) to the hydroxyl equivalent of the fluororesin (A) (hereinafter referred to as T-NCO / OH) is 1.5 or less. preferable. By being 1.5 or less, it is possible to suppress a large amount of the curing agent component that cannot be crosslinked with the fluorine-containing resin, and it is possible to suppress the occurrence of problems such as deterioration of coating film performance and yellowing during paint baking and drying. . In particular, it is preferable that NCO / OH is 0.6 to 1.2 and T-NCO / OH is 1.5 or more.
[0020]
The fluororesin powder coating composition of the present invention can be produced by any known method. For example, after roughly mixing a fluorine-containing resin (A), a polyisocyanate curing agent (B) having a uretdione bond and a blocked polyisocyanate curing agent (C) with a mixer such as a Henschel mixer, biaxial or uniaxial , Or after performing hot melt kneading with a planetary type extruder, cold rolling with a cool roll, pulverizing using a rotary shearing pulverization such as a pin mill, a collision type pulverizer such as a jet mill, etc. It is a common production method to obtain powder as a powdered composition through classification using a mesh, classification using an air separator or the like.
[0021]
Although the particle diameter of the powdery composition is not particularly limited, the 50% volume average particle diameter is preferably 15 to 200 μm, more preferably 20 to 150 μm, and particularly preferably 20 to 100 μm. The 50% volume average particle diameter is the particle diameter at the entire 50% occupancy when the volume occupancy at each particle diameter is accumulated.
[0022]
In the composition for a fluororesin powder coating material of the present invention, the degree of the stigma pattern can be further finely adjusted by adjusting the particle size of the powdery composition. Specifically, in the particle size distribution, if the maximum particle size is large, the unevenness difference when forming the coating film is large, and if it is small, the unevenness difference is small.
[0023]
In the composition for a fluorine-containing resin powder coating of the present invention, a pigment used in a normal powder coating can be used.
In the present invention, a pigment having good weather resistance is suitable so that the resin characteristics of the fluororesin (A) can be maximized. Examples of such pigments include metal oxide pigments such as iron oxide, cobalt oxide, bismuth oxide, and surface-treated titanium oxide, and organic pigments such as perylene and diketopyrrolopyrrole.
[0024]
In the present invention, extender pigments, rust preventive pigments and the like can be used as long as they are added so as not to impair the weather resistance.
[0025]
In the composition for a fluororesin powder coating material of the present invention, other additives conventionally used for coating materials can be used as appropriate. Specific examples of other additives include antioxidants, sagging inhibitors, ultraviolet absorbers, light stabilizers, surface conditioners, slip agents, catalysts, and the like. The blending amount (mass basis) of other additives is appropriately selected from the range of about 0.1 to 50 parts with respect to 100 parts of the fluororesin.
[0026]
Moreover, in this invention, in the range which does not impair the weather resistance performance of the coating film formed from a fluorine-containing resin powder coating composition, other resins other than fluorine-containing resin (A), for example, polyester resin, acrylic resin, epoxy You may use resin etc. together.
[0027]
Using the composition for a fluororesin powder coating material of the present invention, it is possible to form a coating film having excellent weather resistance performance and a Chijimi pattern on the surface of various articles. Examples of materials for various articles include, for example, concrete, ALC (lightweight cellular concrete), GRC (glass fiber reinforced concrete), CFRC (carbon fiber reinforced concrete), stone, slate, glass and other inorganic materials, acrylic resin, polycarbonate resin, Organic materials such as vinyl chloride resin and polyethylene resin, rubber and other organic materials, aluminum, copper, brass, titanium, iron, stainless steel, galvanized steel, steel plates and other metal materials, wood, and FRP (glass fiber reinforced synthetic resin) And organic inorganic composite materials such as CFRP (carbon fiber reinforced synthetic resin).
[0028]
The fluorine-containing powder coating composition of the present invention may be applied directly to an article made of these materials, or may be applied after surface treatment such as primer or after undercoating. For materials with insufficient adhesion when applied directly, it is preferable to apply after applying surface treatment such as sanding or undercoating treatment.
[0029]
The fluorine-containing powder coating composition of the present invention is applied to the surface of the following article. For example, transportation equipment such as automobiles, trains, helicopters, boats, bicycles, snow vehicles, ropeways, lifts, fovercrafts, motorcycles, sashes, shutters, water tanks, doors, balconies, building skin panels, roofing materials Building parts such as stairs, skylights, concrete fences, building outer walls, guardrails, pedestrian bridges, soundproof walls, signs, highway side walls, railway viaducts, bridges and other road parts, tanks, pipes, towers, chimneys and other plant parts Agricultural equipment such as greenhouses, greenhouses, silos, agricultural sheets, communication equipment such as power poles, power transmission towers, parabolic antennas, electrical wiring boxes, lighting equipment, air conditioners outdoor equipment, electric equipment such as washing machines, and the like Covers, monuments, tombstones, paving materials, windshield sheets, waterproof sheets, building curing sheets, and the like.
[0030]
An article having a coating film formed from the composition for a fluororesin powder coating material of the present invention has a Chijimi pattern on the surface, and gives a high-class feeling while maintaining excellent weather resistance. For example, after uniformly coating the surface of an article made of a metal material such as stainless steel, zinc phosphate treated steel plate, brass, etc. with a commercially available electrostatic powder coating machine, fluid immersion apparatus, etc., a hot air furnace, an infrared furnace, a dielectric By baking in a heating furnace or the like, a coating film having good weather resistance can be formed.
[0031]
Moreover, even when a trace amount of the composition for a fluororesin powder coating material of the present invention is mixed in a conventional fluororesin powder coating material, the coating film does not cause defects such as repellency.
[0032]
【Example】
Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. In addition, Examples 1-2 are Examples and Examples 3-6 are comparative examples.
[0033]
[Synthesis Example 1]
In a 3000 mL stainless steel pressure-resistant reactor equipped with a stirrer, 1000 g of xylene, 350 g of cyclohexyl vinyl ether (CHVE), 50 g of ethyl vinyl ether (EVE), 100 g of 4-hydroxybutyl vinyl ether (HBVE), 10 g of calcium carbonate and par 0.7 g of butyl perpivalate (PBPV) was charged, and dissolved oxygen in the liquid was removed by solidification and degassing with liquid nitrogen. Next, after introducing 500 g of chlorotrifluoroethylene (CTFE), the temperature was gradually raised and the temperature was maintained at 65 ° C. to carry out the polymerization reaction. After 10 hours, the reaction was stopped by cooling the reactor with water. After cooling the reaction solution to room temperature, the unreacted monomer is purged, the resulting reaction solution is filtered through diatomaceous earth to remove undissolved solids, and a solution of fluorinated copolymer A having a solid content concentration of 50%. Got. This solution was dried under reduced pressure to obtain a solid fluorine-containing copolymer A. The fluorine-containing copolymer A had a Tg of 55 ° C. and a hydroxyl value of 38 mgKOH / g.
[0034]
[Example 1]
580 g of fluorine-containing copolymer A, Clenova BF1540 (trade name: manufactured by Degussa, polyisocyanate curing agent having a uretdione bond with IPDI as the main skeleton) (NCO / OH ratio = 0.9), Clelan Ui ( Product name: 17 g (T-NCO / OH ratio = 1.0) of Bayer, polyisocyanate curing agent blocked with E-CAP with IPDI as main skeleton, 4 g of benzoin, BYK-360P (product) Name: 10 g of an acrylic acid oligomer type leveling agent manufactured by Big Chemie Co., Ltd. was placed in a high-speed mixer, mixed for 1 minute, kneaded with a biaxial kneader (manufactured by Prism Co., Ltd.) adjusted to 120 ° C., and discharged. The kneaded product is cold-rolled with a cooling roll, crushed with a jaw crusher, pulverized with a pin mill, and classified with a 200-mesh net. To obtain particles ▲ 1 ▼ fluorinated powder coating of 50% volume average particle size 32 [mu] m.
[0035]
[Example 2]
Example of preparing 580 g of fluorine-containing copolymer A, 160 g of cleran Ui (T-NCO / OH = 1.0), 4 g of benzoin, 10 g of BYK-364P, 300 g of titanium dioxide (R960 manufactured by DuPont) In the same manner as in No. 1, particles for fluorine-containing powder coating material (2) having a 50% volume average particle diameter of 33 μm were obtained.
[0036]
[Example 3]
580 g of fluorinated copolymer A, 125 g of Clenova BF1540 (NCO / OH ratio = 0.9), 45 g of cleran Ui (T-NCO / OH = 1.1), 4 g of benzoin, BYK-364P (trade name: 10 g of an acrylic acid oligomer-based leveling agent manufactured by BYK-Chemie Co., Ltd. and 300 g of titanium dioxide (R960 manufactured by DuPont) are treated in the same manner as in Preparation Example 1 for a fluorine-containing powder coating material having a 50% volume average particle size of 32 μm. Particles (3) were obtained.
[0037]
[Example 4]
580 g of fluorinated copolymer A, 160 g of Clenova BF1540 (NCO / OH ratio = 0.95), 10 g of cleran Ui (T-NCO / OH = 1.0), 4 g of benzoin, 10 g of BYK-364P, dioxide dioxide 300 g of titanium (R960: trade name, manufactured by DuPont) was treated in the same manner as in Preparation Example 1 to obtain particles (4) for fluorine-containing powder coating material having a 50% volume average particle diameter of 32 μm.
[0038]
[Creation Example 5]
580 g of fluorinated copolymer A, 90 g of Clenova BF1540 (NCO / OH ratio = 1.0), 80 g of cleran Ui, 4 g of benzoin, 10 g of BYK-364P, titanium dioxide (R960 manufactured by DuPont) Were treated in the same manner as in Preparation Example 1 to obtain particles (5) for fluorine-containing powder coating material having a 50% volume average particle diameter of 32 μm.
[0039]
[Creation Example 6]
580 g of fluorinated copolymer A, 170 g of Clenova BF1540, (NCO / OH ratio = 1.0), 4 g of benzoin, 10 g of BYK-364P, 300 g of titanium dioxide (R960 manufactured by DuPont) The same treatment as in Example 1 was performed to obtain particles (6) for fluorine-containing powder coating material having a 50% volume average particle diameter of 32 μm.
[0040]
[Example 1]
Using a powder electrostatic coating device (GX electrostatic coating machine manufactured by Nihon Parkerizing Co., Ltd.), the particles for fluorine-containing powder coating (1) obtained in Preparation Example 1 were coated with a coating thickness of 50 μm at a load voltage of −80 kv. The surface of the chromate-treated aluminum plate was painted and baked so as to be thick, and a coating film was formed. In addition, baking was performed for 20 minutes in 200 degreeC atmosphere using the hot-air circulation type dryer. The coating film evaluation was carried out by visually observing the presence or absence of a Chijimi pattern on the coating film surface, impact resistance, cross-cut adhesion, and weather resistance evaluation. The evaluation results are summarized in Table 1.
Impact resistance: Using a DuPont impact tester, the maximum weight drop height (cm) at which the coating film was not cracked or peeled was measured. The conditions were a punch diameter of 1/2 inch and the weight weight was 500 g.
Cross grid adhesion: 100 square grids of 1 mm square were prepared, and a peel-off test was performed with cello tape (registered trademark) to measure the remaining number.
Weather resistance: Retention rate of 60-degree specular gloss value after 3000 hours of accelerated weather resistance test with a xenon weatherometer.
[0041]
[Example 2]
A coating film was formed in the same manner as in Example 1 except that the fluorine-containing powder coating particle (1) in Example 1 was changed to the fluorine-containing powder coating particle (3) obtained in Preparation Example 3. The membrane was evaluated. The evaluation results are summarized in Table 1.
[0042]
[Examples 3 to 6]
The coating film was the same as in Example 1 except that the fluorine-containing powder coating particle (1) in Example 1 was changed to the fluorine-containing powder coating particle (2), (4), (5), and (6). Table 1 summarizes the results of the evaluation of the coating film and the evaluation of the coating film.
[0043]
[Table 1]

[0044]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the coating film which has the uneven | corrugated pattern which has a fabric-like design property on the surface, and maintains a high-quality feeling, maintaining the outstanding weather resistance performance of a fluororesin can be formed. Furthermore, the coating film made of the composition for fluorine-containing resin powder coating of the present invention has good impact resistance and adhesion to a substrate, and has excellent performance as a coating.

Claims (1)

It contains a fluorine-containing resin (A) having a hydroxyl group, a polyisocyanate curing agent (B) having a uretdione bond, and a blocked polyisocyanate curing agent (C). A composition for a fluororesin powder coating material, comprising 40 parts by mass.