JP3631841B2 - Powder paint - Google Patents

Description

【００３２】
【表２】

【００３３】
実施例１〜５で得られた粉体塗料は、耐ブロッキング性、塗膜の耐候性及び強度がすべて良好であった。
これに対して、比較例１では、ダイマー酸の共重合量が少ないため、エリクセンが低く、比較例２では、ダイマー酸の共重合量が多いため、耐ブロッキング性が不良であった。また、比較例３では、ダイマー酸を共重していないため、エリクセンが低く、比較例４では、イソフタル酸の共重合量が少ないため、耐候性が悪かった。
【００３４】
【発明の効果】
本発明によれば、実用上十分な強度を有し、耐候性に優れた塗膜を与えるとともに、耐ブロッキング性の良好な粉体塗料が提供される。[0001]
[Industrial application fields]
The present invention relates to a powder coating material having practically sufficient strength, giving a coating film excellent in weather resistance and having good blocking resistance.
[0002]
[Prior art]
In recent years, paints with good weather resistance have been demanded for reasons such as maintenance-free. As the powder coating material, an acrylic resin type is known as having good weather resistance. However, acrylic resin-based powder paints are expensive and have very poor compatibility with other paints. If mixed with other paints, they will cause repellency, so the paint line must be isolated. There was a problem.
[0003]
Polyester resin powder coatings do not have such problems, but generally have a problem of insufficient weather resistance, and development of polyester resins for powder coatings with improved weather resistance has been underway.
[0004]
For example, JP-A-2-two hundred eighty-four thousand nine hundred seventy-four, isophthalic acid and cyclohexane dicarboxylic acid as a main acid component, the end groups are predominantly improved weather resistance obtained by blending triglycidyl isocyanurate as a curing agent in the polyester resin is a carboxyl group Also disclosed is a polyester resin composition for powder coatings. However, triglycidyl isocyanurate has recently been pointed out as a sanitary problem regarding mutagenicity and the like, and has a problem in use.
[0005]
Japanese Patent Application Laid-Open No. 6-234951 discloses a powder coating material having improved weather resistance in which isophthalic acid and neopentyl glycol are the main constituent components and an isocyanate curing agent is blended with a polyester resin whose terminal groups are mainly hydroxyl groups. A polyester resin composition is disclosed.
[0006]
However, the powder coating using this resin composition has a problem that the strength of the coating film is slightly insufficient for practical use. In order to solve this problem, there is a method of copolymerizing an aliphatic dicarboxylic acid or an aliphatic diol having a molecular weight of about 160 to 400. In order to obtain a coating film having a practically sufficient strength, these components are added. There was a problem that a large amount of copolymerization had to be performed, the softening point of the resin was greatly lowered, and a blocking phenomenon in which the powder was re-solidified easily occurred.
[0007]
[Problems to be solved by the invention]
The present invention is intended to provide a powder coating material that has a practically sufficient strength, provides a coating film excellent in weather resistance, and has good blocking resistance.
[0008]
(1) A polyester resin having an intrinsic viscosity of 0.15 to 0.40 dl / g and a hydroxyl value of 13 to 85 mgKOH / g, wherein 70 to 99.7 mol% of the total acid component constituting the polyester is isophthalic acid and 0.3 to 3 mol% Is a powder coating using a polyester resin in which is dimer acid, 0 to 29.7 mol% is terephthalic acid, and the alcohol component is mainly composed of neopentyl glycol.
(2) The above-mentioned powder coating material containing an isocyanate curing agent .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0010]
The polyester resin used in the powder coating of the present invention is composed of 70-99.7 mol% of isophthalic acid, 0.3-3 mol% of dimer acid and 0-29.7 mol% of terephthalic acid, and the alcohol component is mainly neopentyl glycol. It consists of
[0011]
When the proportion of isophthalic acid in the acid component is less than the above range or the proportion of terephthalic acid is more than the above range, sufficient weather resistance cannot be obtained. On the other hand, when the proportion of dimer acid is less than the above range, the strength is insufficient, and when it is too large, the softening temperature of the polyester resin is lowered, and when it is used as a powder coating, blocking is liable to occur. In order to satisfy both the strength and the blocking resistance at the same time, the above range is required.
[0012]
As the dimer acid to be copolymerized, one having 36 carbon atoms is preferable. That is, it is obtained by dimerizing an unsaturated fatty acid having 18 carbon atoms, such as linoleic acid and linolenic acid, and one having an unsaturated bond can be used as it is, but it is preferably used after hydrogenation.
[0013]
In the dimerization reaction of the unsaturated fatty acid, a monomer and a trimer are produced together with the dimer. The dimer is 94 mol% or more, the monomer is 2 mol% or less, and the trimer. The body and the like are preferably used in an amount of 4 mol% or less. When the amount of the monomer is large, the reactivity is lowered and it is difficult to increase the degree of polymerization. When the amount of the trimer is large, the three-dimensional structure is produced in the resin production stage and the smoothness of the coating film is impaired.
[0014]
Dimer acid is commercially available from many companies, but those satisfying the above conditions include “Enpole 1008” manufactured by Henkel Emery, “PRIPOL 1009” manufactured by Unikema, and the like. Good.
[0015]
Along with the dicarboxylic acid as described above, a dicarboxylic acid such as phthalic acid, naphthalenedicarboxylic acid, adipic acid, azelaic acid, and cyclohexanedicarboxylic acid may be used in combination as long as the effects of the present invention are not impaired. In addition, a trivalent or higher carboxylic acid such as trimellitic acid, pyromellitic acid, trimesic acid or the like may be used in combination as long as the polyester resin is not gelled.
[0016]
Moreover, as a glycol component, neopentyl glycol is mainly used and it is preferable that the ratio is 70 mol% or more of a glycol component. When neopentyl glycol is less than 70 mol%, the weather resistance is insufficient.
[0017]
Along with neopentyl glycol, ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, ethylene oxide of bisphenol A, as long as the effects of the present invention are not impaired. Diols such as adducts and ethylene oxide adducts of bisphenol S may be used in combination. Moreover, you may use together trivalent or more alcohols, such as a trimethylol propane, glycerol, and a pentaerythritol, in the range which does not gelatinize a polyester resin.
[0018]
Further, a small amount of hydroxycarboxylic acid such as 4-hydroxybenzoic acid or ε-caprolactone may be used in combination.
[0019]
The polyester resin used in the powder coating material of the present invention needs to have an intrinsic viscosity of 0.15 to 0.40 dl / g, preferably 0.20 to 0.35 dl / g. If the intrinsic viscosity of the polyester resin is less than 0.15 dl / g, the softening temperature of the resin tends to decrease and the blocking resistance tends to decrease, and the strength of the coating film tends to decrease, exceeding 0.40 dl / g. And there exists a tendency for the grindability of resin to worsen.
[0020]
The polyester resin used in the powder coating of the present invention must have a hydroxyl value of 13 to 85 mgKOH / g, preferably 25 to 60 mgKOH / g. If the hydroxyl value of the polyester resin is less than 13 mgKOH / g, the surface of the coating tends to have large irregularities and the smoothness tends to decrease, and if it exceeds 85 mgKOH / g, the strength of the coating tends to decrease. .
[0021]
Furthermore, the polyester resin used in the powder coating of the present invention preferably has a softening temperature in the range of 50 to 150 ° C. If the softening temperature is less than 50 ° C, the anti-blocking property tends to be inferior. On the other hand, if the softening temperature exceeds 150 ° C, it is necessary to increase the kneading temperature at the time of coating production, and the resin and curing during kneading As a result, the smoothness and strength of the coating film tend to decrease.
[0022]
The polyester resin used in the powder coating of the present invention is esterified or transesterified at a temperature of 200 to 280 ° C. by a conventional method using the above acid component and alcohol component (including their ester-forming derivatives) as raw materials. After the reaction, a polycondensation reaction is performed at a temperature of 200 to 300 ° C., preferably 230 to 290 ° C. under a reduced pressure of 5 hPa or less to obtain a polyester having a high degree of polymerization, and an alcohol component is added thereto to depolymerize the reaction It can be prepared by the method of performing.
[0023]
Moreover, after performing esterification or transesterification by a conventional method, until it reaches a predetermined intrinsic viscosity at a temperature of 200 to 300 ° C., preferably 220 to 280 ° C. under a normal pressure or a reduced pressure of about 50 to 100 hPa. It can also be prepared by a method of performing a polycondensation reaction.
[0024]
Moreover, a well-known reaction catalyst etc. can be used in esterification, transesterification reaction, and polycondensation reaction.
[0025]
The polyester resin thus obtained is mixed with an isocyanate curing agent to form a powder paint .
[0026]
Preferred isocyanate-based curing agents include blocked isocyanate-based curing agents and blocked hydrogenated diphenylmethane diisocyanate-based curing agents that exhibit no activity below a certain temperature. Specific examples include isophorone diisocyanate-based curing blocked with ε-caprolactam. "Vestagon B 1530" manufactured by Huls, a chemical agent, and "Vestagon BF 1540" manufactured by the same, an isophorone diisocyanate-based curing agent that does not contain a blocking agent and has a self-blocking isocyanate group, hydrogenated with ε-caprolactam Examples thereof include “24-2430” and “24-2431” manufactured by McWHORTER, which are diphenylmethane diisocyanate curing agents.
[0027]
The amount of the curing agent is suitably a functional group amount substantially corresponding to the hydroxyl group amount of the polyester resin, preferably 0.8 to 1.2 times equivalent.
[0028]
The powder coating of the present invention comprises a mixture of a polyester resin and a curing agent as described above, and a curing catalyst, a leveling agent, and other additives, for example, a pigment such as titanium dioxide, if necessary. And can be prepared by kneading at 70 to 150 ° C.
[0029]
【Example】
Next, the present invention will be described specifically by way of examples.
In addition, the characteristic value in an Example was calculated | required with the following method.
(A) Measurement was carried out at 20 ° C. using an equal weight mixture of intrinsic viscosity phenol and ethane tetrachloride as a solvent.
(B) After acetylation with hydroxyl value acetic anhydride, titration was performed with a potassium hydroxide methanol solution.
(C) Softening temperature 60-100 Resin pulverized to a mesh size is filled in a bottomed glass tube with a diameter of 2.5 mm and a height of 150 mm up to a height of 30 mm, and the resin filling part is immersed in an oil bath, The temperature was raised at a rate of 1 ° C./min, and the temperature at which liquefaction started was determined visually to obtain the softening temperature.
(D) Fill a bottomed glass tube with a diameter of 3 cm and a height of 7 cm with a blocking-resistant powder paint to a height of 4 cm, leave it in a constant temperature bath at 40 degrees for one week, and then invert the glass tube to apply the paint. It was taken out and evaluated as follows depending on the state of the paint.
Good: The paint has no lumps or small lumps and the lumps cannot be lifted by hand.
Poor: The paint clumps up into large chunks that can be lifted by hand.
(E) Impact resistance It was determined using a sphere having a diameter of 1.27 cm and a weight of 1 kg according to JIS K 5400.
(F) 60 degree specular glossiness It calculated | required according to JISK5400.
(G) It calculated | required according to Eriksen JISZ2247. (Those that do not break even if extruded 5 mm or more are acceptable.)
(H) Accelerated weather resistance According to JIS K 5400, the gloss retention after 1000 hours irradiation was determined using a WEL-6XS-HC-B / Ec type sunshine weather meter (manufactured by Suga Test Instruments Co., Ltd.).
[0030]
Examples 1-5 and Comparative Examples 1-4
The raw material compounds shown in Tables 1 and 2 were charged into the esterification reaction tank in the amounts (mole parts) shown in Tables 1 and 2, and esterified at a pressure of 0.05 to 1.5 MPa and a temperature of 200 to 260 ° C. for 4 hours. The reaction was carried out.
After the obtained esterified product was transferred to a polycondensation reaction tank, 4 × 10 ⁻⁴ mol / acid component of 1 mol of antimony trioxide was added, the pressure was reduced to 0.4 hPa, and a polycondensation reaction was performed at 280 ° C. for 4 hours. A polyester having an intrinsic viscosity of 0.45 dl / g was obtained.
Next, the depolymerizing agent shown in Table 1 and Table 2 was added to this polyester in the amount (mole part) shown in Table 1 and Table 2, and the depolymerization reaction was performed at 270 ° C. for 1 hour under normal pressure. And the polyester resin of the characteristic value shown in Table 2 was obtained.
Polyester resin obtained, blocked isocyanate curing agent: “Vestagon B 1530” or “Vestagon BF 1540” manufactured by Huls, dioctyl tin maleate curing catalyst: “Stan OMF” manufactured by Sansha Co., Ltd., butyl polyacrylate Leveling agent: “Acronal 4F” manufactured by Bassf, benzoin and rutile-type titanium dioxide pigment: CR-90 manufactured by Ishihara Sangyo Co., Ltd. are blended in the amounts (parts by weight) shown in Tables 1 and 2 and FM 10B type Henschel mixer (Mitsui) After dry blending at Miike Seisakusho, melt-knead at 110 ° C using a PR-46 co-kneader (manufactured by Buss), cool, grind, classify with a 140 mesh wire mesh, Obtained.
The obtained powder coating was electrostatically coated on a zinc phosphate-treated steel sheet and baked under the conditions of 180 ° C. × 20 minutes.
The results of evaluating the performance of the coating film are shown in Tables 1 and 2.
[0031]
[Table 1]

[0032]
[Table 2]

[0033]
The powder coatings obtained in Examples 1 to 5 were all good in blocking resistance, weather resistance and strength of the coating film.
On the other hand, in Comparative Example 1, since the amount of dimer acid copolymerization was small, the elixir was low. In Comparative Example 2, the amount of dimer acid copolymerization was large, and thus the blocking resistance was poor. In Comparative Example 3, since dimer acid was not co-polymerized, the elixir was low, and in Comparative Example 4, the amount of isophthalic acid copolymerized was small, so the weather resistance was poor.
[0034]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, while providing a coating film which has practically sufficient intensity | strength and was excellent in the weather resistance, the powder coating material with favorable blocking resistance is provided.

Claims (2)

A polyester resin having an intrinsic viscosity of 0.15 to 0.40 dl / g and a hydroxyl value of 13 to 85 mgKOH / g, wherein 70 to 99.7 mol% of the total acid component constituting the polyester is isophthalic acid, and 0.3 to 3 mol% is dimer acid 0-29.7 mol% of terephthalic acid, and a powder coating using a polyester resin whose alcohol component is mainly composed of neopentyl glycol. The powder coating material according to claim 1, wherein an isocyanate curing agent is blended .